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+*** START OF THE PROJECT GUTENBERG EBOOK 15884 ***
+Young Folks' Library
+
+Selections from the Choicest Literature of All
+Lands; Folk-Lore, Fairy Tales, Fables, Legends,
+Natural History, Wonders of Earth, Sea
+and Sky, Animal Stories, Sea Tales,
+Brave Deeds, Explorations, Stories
+of School and College Life,
+Biography, History, Patriotic
+Eloquence, Poetry
+
+Third Edition
+
+Revised in Conference by
+
+   Thomas Bailey Aldrich, Editor-in-Chief,
+   President William Jewett Tucker,
+   Hamilton Wright Mabie,
+   Henry Van Dyke,
+   Nathan Haskell Dole
+
+Twenty Volumes   Richly Illustrated
+
+Boston
+Hall and Locke Company
+Publishers
+Stanhope Press
+F.H. Gilson Company
+Boston, U.S.A.
+
+1902
+
+
+
+
+
+
+EDITORIAL BOARD
+
+
+   THOMAS BAILEY ALDRICH, Editor-in-chief,
+   Author, poet, former editor _Atlantic Monthly,_ Boston, Mass.
+
+   The HON. JOHN D. LONG,
+   Secretary of the United States Navy, Boston.
+
+   HAMILTON WRIGHT MABIE, LL.D.,
+   Author, literarian, associate editor _The Outlook_, New York.
+
+   ERNEST THOMPSON SETON,
+   Artist, author, New York.
+
+   JOHN TOWNSEND TROWBRIDGE,
+   Author, poet, and editor, Arlington, Mass.
+
+   The REVEREND CYRUS TOWNSEND BRADY,
+   Archdeacon, author, Philadelphia.
+
+   JOEL CHANDLER HARRIS,
+   Humorous writer, Atlanta, Ga.
+
+   MARY HARTWELL CATHERWOOD,
+   Historical novelist, Chicago.
+
+   LAURA E. RICHARDS,
+   Author, Gardiner, Me.
+
+   ROSWELL FIELD,
+   Author, editor _The Evening Post_, Chicago.
+
+   TUDOR JENKS,
+   Author, associate editor _Saint Nicholas_, New York.
+
+   GEORGE A. HENTY,
+   Traveller, author, London, England.
+
+   KIRK MUNROE,
+   Writer of stories for boys, Cocoanut Grove, Fla.
+
+   EDITH M. THOMAS,
+   Poet, West New Brighton, N.Y.
+
+   CAROLINE TICKNOR,
+   Author, editor, Boston.
+
+   NATHAN HASKELL DOLE,
+   Author, translator, literary editor _Current History_, Boston.
+
+   WILLIAM RAINEY HARPER, D.D., LL.D.,
+   President Chicago University.
+
+   DAVID STARR JORDAN, M.D., LL.D.,
+   President Leland Stanford Junior University, naturalist, writer,
+   Stanford University, Cal.
+
+   CHARLES ELIOT NORTON, A.M., LL.D., etc.,
+   Scholar, author, Emeritus Professor of Art at Harvard University.
+
+   HENRY VAN DYKE, D.D., LL.D.,
+   Clergyman, author, Professor Princeton University.
+
+   The REVEREND THOMAS J. SHAHAN,
+   Dean of the Faculty of Divinity, Professor of Early Ecclesiastical
+   History, Catholic University, Washington, D.C.
+
+   WILLIAM P. TRENT,
+   Author, editor, Professor of English Literature, Columbia University,
+   New York City.
+
+   EDWARD SINGLETON HOLDEN, A.M., LL.D.,
+   Ex-president University of California, astronomer, author,
+   U.S. Military Academy, West Point.
+
+   EDWIN ERLE SPARKS,
+   Professor of American History, Chicago University.
+
+   The VERY REV. GEORGE M. GRANT, D.D., LL.D.,
+   Educator, author, vice-principal Queen's College, Kingston, Ont.
+
+   BARONESS VON BULOW,
+   Educator, author, Dresden, Germany.
+
+   ABBIE FARWELL BROWN,
+   Author, Boston.
+
+   CHARLES WELSH, Managing Editor,
+   Author, lecturer, editor, Winthrop Highlands, Mass.
+
+
+
+
+LIST OF VOLUMES
+
+
+   VOLUME I.
+
+   THE STORY TELLER
+   Edited by CHARLES ELIOT NORTON
+
+
+   VOLUME II.
+
+   THE MERRY MAKER
+   Edited by JOEL CHANDLER HARRIS
+
+
+   VOLUME III.
+
+   FAMOUS FAIRY TALES
+   Edited by ROSWELL FIELD
+
+
+   VOLUME IV.
+
+   TALES OF FANTASY
+   Edited by TUDOR JENKS
+
+
+   VOLUME V.
+   MYTHS AND LEGENDS
+   Edited by THOMAS J. SHAHAN
+
+
+   VOLUME VI.
+
+   THE ANIMAL STORY BOOK
+   Edited by ERNEST THOMPSON SETON
+
+
+   VOLUME VII.
+
+   SCHOOL AND COLLEGE DAYS
+   Edited by KIRK MUNROE and
+   MARY HARTWELL CATHERWOOD
+
+
+   VOLUME VIII.
+
+   BOOK OF ADVENTURE
+   Edited by NATHAN HASKELL DOLE
+
+
+   VOLUME IX.
+
+   FAMOUS EXPLORERS
+   Edited by EDWIN ERLE SPARKS
+
+
+   VOLUME X.
+
+   BRAVE DEEDS
+   Edited by JOHN TOWNSEND TROWBRIDGE
+
+
+   VOLUME XI.
+
+   WONDERS OF EARTH, SEA AND SKY
+   Edited by EDWARD SINGLETON HOLDEN
+
+
+   VOLUME XII.
+
+   FAMOUS TRAVELS
+   Edited by GEORGE A. HENTY
+
+
+   VOLUME XIII.
+
+   SEA STORIES
+   Edited by CYRUS TOWNSEND BRADY
+
+
+   VOLUME XIV.
+
+   A BOOK OF NATURAL HISTORY
+   Edited by DAVID STARR JORDAN
+
+
+   VOLUME XV.
+
+   HISTORIC SCENES IN FICTION
+   Edited by HENRY VAN DYKE
+
+
+   VOLUME XVI.
+
+   FAMOUS BATTLES BY LAND AND SEA
+   Edited by JOHN D. LONG
+
+
+   VOLUME XVII.
+
+   MEN WHO HAVE RISEN
+   Edited by HAMILTON WRIGHT MABIE.
+
+
+   VOLUME XVIII.
+
+   BOOK OF PATRIOTISM
+   Edited by
+
+
+   VOLUME XIX.
+
+   LEADERS OF MEN, OR HISTORY TOLD IN BIOGRAPHY
+   Edited by WILLIAM RAINEY HARPER
+
+
+   VOLUME XX.
+
+   FAMOUS POEMS
+   Selected by THOMAS BAILEY ALDRICH,
+   with Poetical Foreword by EDITH M. THOMAS.
+
+
+
+[Illustration: A GEYSER]
+
+
+
+
+Volume XI: WONDERS OF EARTH, SEA AND SKY
+
+Edited by EDWARD SINGLETON HOLDEN
+
+Boston
+Hall and Locke Company Publishers
+
+1902
+
+
+
+
+CONTENTS
+
+
+  LIST OF ILLUSTRATIONS                xi
+
+  THE MARVELS OF NATURE              xiii
+  BY PROFESSOR E.S. HOLDEN.
+
+  WHAT THE EARTH'S CRUST IS MADE OF     1
+  BY AGNES GIBERNE.
+
+  AMERICA THE OLD WORLD                45
+  BY LOUIS AGASSIZ.
+
+  SOME RECORDS OF THE ROCKS            77
+  BY N.S. SHALER.
+
+  THE PITCH LAKE IN THE WEST INDIES    97
+  BY CHARLES KINGSLEY.
+
+  A STALAGMITE CAVE                   111
+  BY SIR C. WYVILLE THOMSON.
+
+  THE BIG TREES OF CALIFORNIA         119
+  BY ALFRED RUSSEL WALLACE.
+
+  WHAT IS EVOLUTION?                  127
+  BY PROFESSOR EDWARD S. HOLDEN.
+
+  HOW THE SOIL IS MADE                135
+  BY CHARLES DARWIN.
+
+  ZOÖLOGICAL MYTHS                    143
+  BY ANDREW WILSON.
+
+  ON A PIECE OF CHALK                 171
+  BY T.H. HUXLEY.
+
+  A BIT OF SPONGE                     205
+  BY A. WILSON.
+
+  THE GREATEST SEA-WAVE EVER KNOWN    211
+  BY R.A. PROCTOR.
+
+  THE PHOSPHORESCENT SEA              228
+  BY W.S. DALLAS.
+
+  COMETS                              251
+  BY CAMILLE FLAMMARION.
+
+  THE TOTAL SOLAR ECLIPSE OF 1883     261
+  BY E.S. HOLDEN.
+
+  HALOS--PARHELIA--THE SPECTRE OF
+    THE BROCKEN, ETC.                 268
+  BY CAMILLE FLAMMARION.
+
+  THE PLANET VENUS                    282
+  BY AGNES M. CLERKE.
+
+  THE STARS                           296
+  BY SIR R.S. BALL.
+
+  RAIN AND SNOW                       342
+  BY JOHN TYNDALL.
+
+  THE ORGANIC WORLD                   357
+  BY ST. GEORGE MIVART.
+
+  INHABITANTS OF MY POOL              366
+  BY ARABELLA B. BUCKLEY.
+
+  BIOGRAPHICAL NOTES.                 387
+
+  SUGGESTIONS FOR SUPPLEMENTARY
+    READING.                          389
+
+
+NOTE.
+
+The publishers' acknowledgments are due to Messrs. Houghton, Mifflin &
+Co., for permission to use "America and the Old World," by L. Agassiz;
+to Messrs. D.C. Heath & Co. for permission to use "Some Records of the
+Rocks," by Professor N.S. Shaler; and to Professor E.S. Holden for
+permission to use "What is Evolution?" and "An Astronomer's Voyage to
+Fairy Land."
+
+
+
+
+LIST OF COLORED ILLUSTRATIONS
+
+  A GEYSER. _Frontispiece,  See Page_  47
+
+  VIEW IN A CAÑON         _Face Page_  12
+
+  A VOLCANO                            48
+
+  A STALAGMITE CAVE                   116
+
+  WHERE SPONGES GROW                  208
+
+  A COMET                             254
+
+  THE SPECTRE OF THE BROCKEN          272
+
+
+AND ONE HUNDRED AND SIXTY-FOUR BLACK AND WHITE ILLUSTRATIONS IN THE
+TEXT.
+
+
+
+
+THE MARVELS OF NATURE
+
+BY EDWARD S. HOLDEN, M.A., Sc.D. LL.D.
+
+
+The Earth, the Sea, the Sky, and their wonders--these are the themes
+of this volume. The volume is so small, and the theme so vast! Men
+have lived on the earth for hundreds of thousands of years; and its
+wonders have increased, not diminished, with their experience.
+
+To our barbarous ancestors of centuries ago, all was mystery--the
+thunder, the rainbow, the growing corn, the ocean, the stars.
+Gradually and by slow steps they learned to house themselves in trees,
+in caves, in huts, in houses; to find a sure supply of food; to
+provide a stock of serviceable clothing. The arts of life were born;
+tools were invented; the priceless boon of fire was received; tribes
+and clans united for defence; some measure of security and comfort was
+attained.
+
+With security and comfort came leisure; and the mind of early Man
+began curiously to inquire the meaning of the mysteries with which he
+was surrounded. That curious inquiry was the birth of Science. Art was
+born when some far-away ancestor, in an idle hour, scratched on a
+bone the drawing of two of his reindeer fighting, or carved on the
+walls of his cave the image of the mammoth that he had but lately
+slain with his spear and arrows.
+
+In a mind that is completely ignorant there is no wonder. Wonder is
+the child of knowledge--of partial and imperfect knowledge, to be
+sure, but still, of knowledge. The very first step in Science is to
+make an inventory of external Nature (and by and by of the faculties
+of the mind that thinks). The second step is to catalogue similar
+appearances together. It is a much higher flight to seek the causes of
+likenesses thus discovered.
+
+A few of the chapters of this volume are items in a mere catalogue of
+wonders, and deserve their place by accurate and eloquent description.
+Most of them, however, represent higher stages of insight. In the
+latter, Nature is viewed not only with the eye of the observer, but
+also with the mind's eye, curious to discover the reasons for things
+seen. The most penetrating inward inquiry accompanies the acutest
+external observation in such chapters as those of Darwin and Huxley,
+here reprinted.
+
+Now, the point not to be overlooked is this: to Darwin and Huxley, as
+to their remote and uncultured ancestors, the World--the Earth, the
+Sea, the Sky--is full of wonders and of mysteries, but the wonders are
+of a higher order. The problems of the thunder and of the rainbow as
+they presented themselves to the men of a thousand generations ago,
+have been fully solved: but the questions; what is the veritable
+nature of electricity, exactly how does it differ from light, are
+still unanswered. And what are simple problems like these to the
+questions: what is love; why do we feel a sympathy with this person,
+an antipathy for that; and others of the sort? Science has made almost
+infinite advances since pre-historic man first felt the feeble current
+of intellectual curiosity amid his awe of the storm; it has still to
+grow almost infinitely before anything like a complete explanation
+even of external Nature is achieved.
+
+Suppose that, at some future day, all physical and mechanical laws
+should be found to be direct consequences of a single majestic law,
+just as all the motions of the planets are (but--are they?) the direct
+results of the single law of gravitation. Gravitation will, probably,
+soon be explained in terms of some remoter cause, but the reason of
+that single and ultimate law of the universe which we have imagined
+would still remain unknown. Human knowledge will always have limits,
+and beyond those limits there will always be room for mystery and
+wonder. A complete and exhaustive explanation of the world is
+inconceivable, so long as human powers and capacities remain at all as
+they now are.
+
+It is important to emphasize such truths, especially in a book
+addressed to the young. When a lad hears for the first time that an
+astronomer, by a simple pointing of his spectroscope, can determine
+with what velocity a star is approaching the earth, or receding from
+it, or when he hears that the very shape of the revolving masses of
+certain stars can be calculated from simple measures of the sort, he
+is apt to conclude that Science, which has made such astounding
+advances since the days of Galileo and Newton, must eventually reach a
+complete explanation of the entire universe. The conclusion is not
+unnatural, but it is not correct. There are limits beyond which
+Science, in this sense, cannot go. Its scope is limited. Beyond its
+limits there are problems that it cannot solve, mysteries that it
+cannot explain.
+
+At the present moment, for example, the nature of Force is unknown. A
+weight released from the hand drops to the earth. Exactly what is the
+nature of the force with which the earth attracts it? We do not know,
+but it so happens that it is more than likely that an explanation will
+be reached in our own day. Gravity will be explained in terms of some
+more general forces. The mystery will be pushed back another step, and
+yet another and another. But the progress is not indefinite. If all
+the mechanical actions of the entire universe were to be formulated as
+the results of a single law or cause, the cause of that cause would be
+still to seek, as has been said.
+
+We have every right to exult in the amazing achievements of Science;
+but we have not understood them until we realize that the universe of
+Science has strict limits, within which all its conquests must
+necessarily be confined. Humility, and not pride, is the final lesson
+of scientific work and study.
+
+       *       *       *       *       *
+
+The choice of the selections printed in this volume has been
+necessarily limited by many hampering conditions, that of mere space
+being one of the most harassing. Each of the chapters might readily be
+expanded into a volume. Volumes might be added on topics almost
+untouched here. It has been necessary to pass over almost without
+notice matters of surpassing interest and importance: Electricity and
+its wonderful and new applications; the new Biology, with its views
+upon such fundamental questions as the origins of life and death;
+modern Astronomy, with its far-reaching pronouncements upon the fate
+of universes. All these can only be touched lightly, if at all. It is
+the chief purpose of this volume to point the way towards the most
+modern and the greatest conclusions of Science, and to lay foundations
+upon which the reading of a life-time can be laid.
+
+[Illustration: Signature: Edward S. Holden]
+
+UNITED STATES MILITARY ACADEMY, WEST POINT, _January 1, 1902_.
+
+
+
+
+WONDERS OF EARTH, SEA, AND SKY
+
+
+
+
+WHAT THE EARTH'S CRUST IS MADE OF
+
+(FROM THE WORLD'S FOUNDATIONS.)
+
+BY AGNES GIBERNE.
+
+
+     "Stand still and consider the wondrous works of God."
+
+[Illustration]
+
+What is the earth made of--this round earth upon which we human beings
+live and move?
+
+A question more easily asked than answered, as regards a very large
+portion of it. For the earth is a huge ball nearly eight thousand
+miles in diameter, and we who dwell on the outside have no means of
+getting down more than a very little way below the surface. So it is
+quite impossible for us to speak positively as to the inside of the
+earth, and what it is made of. Some people believe the earth's inside
+to be hard and solid, while others believe it to be one enormous lake
+or furnace of fiery melted rock. But nobody really knows.
+
+This outside crust has been reckoned to be of many different
+thicknesses. One man will say it is ten miles thick, and another will
+rate it at four hundred miles. So far as regards man's knowledge of
+it, gained from mining, from boring, from examination of rocks, and
+from reasoning out all that may be learned from these observations, we
+shall allow an ample margin if we count the field of geology to extend
+some twenty miles downwards from the highest mountain-tops. Beyond
+this we find ourselves in a land of darkness and conjecture.
+
+Twenty miles is only one four-hundredth part of the earth's
+diameter--a mere thin shell over a massive globe. If the earth were
+brought down in size to an ordinary large school globe, a piece of
+rough brown paper covering it might well represent the thickness of
+this earth-crust, with which the science of geology has to do. And the
+whole of the globe, this earth of ours, is but one tiny planet in the
+great Solar System. And the centre of that Solar System, the blazing
+sun, though equal in size to more than a million earths, is yet
+himself but one star amid millions of twinkling stars, scattered
+broadcast through the universe. So it would seem at first sight that
+the field of geology is a small field compared with that of
+astronomy....
+
+With regard to the great bulk of the globe little can be said. Very
+probably it is formed through and through of the same materials as the
+crust. This we do not know. Neither can we tell, even if it be so
+formed, whether the said materials are solid and cold like the
+outside crust, or whether they are liquid with heat. The belief has
+been long and widely held that the whole inside of the earth is one
+vast lake or furnace of melted fiery-hot material, with only a thin
+cooled crust covering it. Some in the present day are inclined to
+question this, and hold rather that the earth is solid and cold
+throughout, though with large lakes of liquid fire here and there,
+under or in her crust, from which our volcanoes are fed....
+
+The materials of which the crust is made are many and various; yet,
+generally speaking, they may all be classed under one simple word, and
+that word is--_Rock_.
+
+It must be understood that, when we talk of rock in this geological
+sense, we do not only mean hard and solid stone, as in common
+conversation. Rock may be changed by heat into a liquid or "molten"
+state, as ice is changed by heat to water. Liquid rock may be changed
+by yet greater heat to vapor, as water is changed to steam, only we
+have in a common way no such heat at command as would be needed to
+effect this. Rock may be hard or soft. Rock maybe chalky, clayey, or
+sandy. Rock may be so close-grained that strong force is needed to
+break it; or it may be so porous--so full of tiny holes--that water
+will drain through it; or it may be crushed and crumbled into loose
+grains, among which you can pass your fingers.
+
+The cliffs above our beaches are rock; the sand upon our seashore is
+rock; the clay used in brick-making is rock; the limestone of the
+quarry is rock; the marble of which our mantel-pieces are made is
+rock. The soft sandstone of South Devon, and the hard granite of the
+north of Scotland, are alike rock. The pebbles in the road are rock;
+the very mould in our gardens is largely composed of crumbled rock. So
+the word in its geological sense is a word of wide meaning.
+
+Now the business of the geologist is to read the history of the past
+in these rocks of which the earth's crust is made. This may seem a
+singular thing to do, and I can assure you it is not an easy task.
+
+For, to begin with, the history itself is written in a strange
+language, a language which man is only just beginning to spell out and
+understand. And this is only half the difficulty with which we have to
+struggle.
+
+If a large and learned book were put before you and you were set to
+read it through, you would perhaps, have no insurmountable difficulty,
+with patience and perseverance, in mastering its meaning.
+
+But how if the book were first chopped up into pieces, if part of it
+were flung away out of reach, if part of it were crushed into a pulp,
+if the numbering of the pages were in many places lost, if the whole
+were mixed up in confusion, and if _then_ you were desired to sort,
+and arrange, and study the volume?
+
+Picture to yourself what sort of a task this would be, and you will
+have some idea of the labors of the patient geologist.
+
+Rocks may be divided into several kinds or classes. For the present
+moment it will be enough to consider the two grand
+divisions--_Stratified rocks_ and _Unstratified rocks_.
+
+Unstratified rocks are those which were once, at a time more or less
+distant, in a melted state from intense heat, and which have since
+cooled into a half _crystallized_ state; much the same as water, when
+growing colder, cools and crystallizes into ice. Strictly speaking, ice
+is rock, just as much as granite and sandstone are rock. Water itself
+is of the nature of rock, only as we commonly know it in the liquid
+state we do not commonly call it so.
+
+[Illustration: UNSTRATIFIED ROCK.--A VOLCANIC BLOCK.]
+
+"Crystallization" means those particular forms or shapes in which the
+particles of a liquid arrange themselves, as that liquid hardens into
+a solid--in other words, as it freezes. Granite, iron, marble, are
+frozen substances, just as truly as ice is a frozen substance; for
+with greater heat they would all become liquid like water. When a
+liquid freezes, there are always crystals formed, though these are not
+always visible without the help of a microscope. Also the crystals are
+of different shapes with different substances.
+
+If you examine the surface of a puddle or pond, when a thin covering
+of ice is beginning to form, you will be able to see plainly the
+delicate sharp needle-like forms of the ice crystals. Break a piece of
+ice, and you will find that it will not easily break just in any way
+that you may choose, but it will only split along the lines of these
+needle-like crystals. This particular mode of splitting in a
+crystallized rock is called the _cleavage_ of that rock.
+
+Crystallization may take place either slowly or rapidly, and either
+in the open air or far below ground. The lava from a volcano is an
+example of rock which has crystallized rapidly in the open air; and
+granite is an example of rock which has crystallized slowly
+underground beneath great pressure.
+
+Stratified rocks, on the contrary, which make up a very large part of
+the earth's crust, are not crystallized. Instead of having cooled from
+a liquid into a solid state, they have been slowly _built up_, bit by
+bit and grain upon grain, into their present form, through long ages
+of the world's history. The materials of which they are made were
+probably once, long, long ago, the crumblings from granite and other
+crystallized rocks, but they show now no signs of crystallization.
+
+
+[Illustration: SECTION OF STRATIFIED ROCKS.
+
+_a._ Conglomerate. _b._ Pebbly Sandstone, _c._ Thin-bedded Sandstone,
+_d._ Shelly Sandstone, _e._ Shale. _f._ Limestone.]
+
+They are called "stratified" because they are in themselves made up of
+distinct layers, and also because they lie thus one upon another in
+layers, or _strata_, just as the leaves of a book lie, or as the
+bricks of a house are placed.
+
+Throughout the greater part of Europe, of Asia, of Africa, of North
+and South America, of Australia, these rocks are to be found,
+stretching over hundreds of miles together, north, south, east, and
+west, extending up to the tops of some of the earth's highest
+mountains, reaching down deep into the earth's crust. In many parts if
+you could dig straight downwards through the earth for thousands of
+feet, you would come to layer after layer of these stratified rocks,
+one kind below another, some layers thick, some layers thin, here a
+stratum of gravel, there a stratum of sandstone, here a stratum of
+coal, there a stratum of clay.
+
+But how, when, where, did the building up of all these rock-layers
+take place?
+
+[Illustration: THE BEACH IN THE FOREGROUND IS A ROCKY SHELF, THE
+REMNANT OF THE CLIFF WHICH ONCE EXTENDED OUT TO THE ISLAND.]
+
+
+People are rather apt to think of land and water on the earth as if
+they were fixed in one changeless form,--as if every continent and
+every island were of exactly the same shape and size now that it
+always has been and always will be.
+
+Yet nothing can be further from the truth. The earth-crust is a scene
+of perpetual change, of perpetual struggle, of perpetual building up,
+of perpetual wearing away.
+
+The work may go on slowly, but it does go on. The sea is always
+fighting against the land, beating down her cliffs, eating into her
+shores, swallowing bit by bit of solid earth; and rain and frost and
+inland streams are always busily at work, helping the ocean in her
+work of destruction. Year by year and century by century it continues.
+Not a country in the world which is bordered by the open sea has
+precisely the same coast-line that it had one hundred years ago; not a
+land in the world but parts each century with masses of its material,
+washed piecemeal away into the ocean.
+
+Is this hard to believe? Look at the crumbling cliffs around old
+England's shores. See the effect upon the beach of one night's fierce
+storm. Mark the pathway on the cliff, how it seems to have crept so
+near the edge that here and there it is scarcely safe to tread; and
+very soon, as we know, it will become impassable. Just from a mere
+accident, of course,--the breaking away of some of the earth, loosened
+by rain and frost and wind. But this is an accident which happens
+daily in hundreds of places around the shores.
+
+Leaving the ocean, look now at this river in our neighborhood, and see
+the slight muddiness which seems to color its waters. What from? Only
+a little earth and sand carried off from the banks as it flowed,--very
+unimportant and small in quantity, doubtless, just at this moment and
+just at this spot. But what of that little going on week after week,
+and century after century, throughout the whole course of the river,
+and throughout the whole course of every river and rivulet in our
+whole country and in every other country. A vast amount of material
+must every year be thus torn from the land and given to the ocean. For
+the land's loss here is the ocean's gain.
+
+And, strange to say, we shall find that this same ocean, so busily
+engaged with the help of its tributary rivers in pulling down land, is
+no less busily engaged with their help in building it up.
+
+You have sometimes seen directions upon a vial of medicine to "shake"
+before taking the dose. When you have so shaken the bottle the clear
+liquid grows thick; and if you let it stand for awhile the thickness
+goes off, and a fine grain-like or dust-like substance settles down at
+the bottom--the settlement or _sediment_ of the medicine. The finer
+this sediment, the slower it is in settling. If you were to keep the
+liquid in gentle motion, the fine sediment would not settle down at
+the bottom. With coarser and heavier grains the motion would have to
+be quicker to keep them supported in the water.
+
+Now it is just the same thing with our rivers and streams. Running
+water can support and carry along sand and earth, which in still water
+would quickly sink to the bottom; and the more rapid the movement of
+the water, the greater is the weight it is able to bear.
+
+This is plainly to be seen in the case of a mountain torrent. As it
+foams fiercely through its rocky bed it bears along, not only mud and
+sand and gravel, but stones and even small rocks, grinding the latter
+roughly together till they are gradually worn away, first to rounded
+pebbles, then to sand, and finally to mud. The material thus swept
+away by a stream, ground fine, and carried out to sea--part being
+dropped by the way on the river-bed--is called _detritus_, which
+simply means _worn-out_ material.
+
+[Illustration: A MOUNTAIN TORRENT.]
+
+The tremendous carrying-power of a mountain torrent can scarcely be
+realized by those who have not observed it for themselves. I have seen
+a little mountain-stream swell in the course of a heavy thunderstorm
+to such a torrent, brown and turbid with earth torn from the
+mountainside, and sweeping resistlessly along in its career a shower
+of stones and rock-fragments. That which happens thus occasionally
+with many streams is more or less the work all the year round of many
+more.
+
+As the torrent grows less rapid, lower down in its course, it ceases
+to carry rocks and stones, though the grinding and wearing away of
+stones upon the rocky bed continues, and coarse gravel is borne still
+upon its waters. Presently the widening stream, flowing yet more
+calmly, drops upon its bed all such coarser gravel as is not worn away
+to fine earth, but still bears on the lighter grains of sand. Next the
+slackening speed makes even the sand too heavy a weight, and that in
+turn falls to line the river-bed, while the now broad and placid
+stream carries only the finer particles of mud suspended in its
+waters. Soon it reaches the ocean, and the flow being there checked by
+the incoming ocean-tide, even the mud can no longer be held up, and it
+also sinks slowly in the shallows near the shore, forming sometimes
+broad mud-banks dangerous to the mariner.
+
+This is the case only with smaller rivers. Where the stream is
+stronger, the mud-banks are often formed much farther out at sea; and
+more often still the river-detritus is carried away and shed over the
+ocean-bed, beyond the reach of our ken. The powerful rush of water in
+earth's greater streams bears enormous masses of sand and mud each
+year far out into the ocean, there dropping quietly the gravel, sand,
+and earth, layer upon layer at the bottom of the sea. Thus pulling
+down and building up go on ever side by side; and while land is the
+theatre oftentimes of decay and loss, ocean is the theatre oftentimes
+of renewal and gain.
+
+
+Did you notice the word "sediment" used a few pages back about the
+settlement at the bottom of a medicine-vial?
+
+There is a second name given to the Stratified Rocks, of which the
+earth's crust is so largely made up. They are called also _Sedimentary
+Rocks_.
+
+The reason is simply this. The Stratified Rocks of the present day
+were once upon a time made up out of the sediment stolen first from
+land and then allowed to settle down on the sea-bottom.
+
+Long, long ago, the rivers, the streams, the ocean, were at work, as
+they are now, carrying away rock and gravel, sand and earth. Then, as
+now, all this material, borne upon the rivers, washed to and fro by
+the ocean, settled down at the mouths of rivers or at the bottom of
+the sea, into a sediment, one layer forming over another, gradually
+built up through long ages. At first it was only a soft, loose, sandy
+or muddy sediment, such as you may see on the seashore, or in a
+mud-bank. But as the thickness of the sediment increased, the weight
+of the layers above gradually pressed the lower layers into firm hard
+rocks; and still, as the work of building went on, these layers were,
+in their turn, made solid by the increasing weight over them. Certain
+chemical changes had also a share in the transformation from soft mud
+to hard rock, which need not be here considered.
+
+All this has through thousands of years been going on. The land is
+perpetually crumbling away; and fresh land under the sea is being
+perpetually built up, from the very same materials which the sea and
+the rivers have so mercilessly stolen from continents and islands.
+This is the way, if geologists rightly judge, in which a very large
+part of the enormous formations of Stratified or Sedimentary Rocks
+have been made.
+
+[Illustration: VIEW IN A CANON.]
+
+So far is clear. But now we come to a difficulty.
+
+The Stratified Rocks, of which a very large part of the continents is
+made, appear to have been built up slowly, layer upon layer, out of
+the gravel, sand, and mud, washed away from the land and dropped on
+the shore of the ocean.
+
+[Illustration: SEA CLIFFS SHOWING A SERIES OF STRATIFIED ROCKS.]
+
+You may see these layers for yourself as you walk out into the
+country. Look at the first piece of bluff rock you come near, and
+observe the clear pencil-like markings of layer above layer--not often
+indeed lying _flat_, one over another, and this must be explained
+later, but however irregularly slanting, still plainly visible. You
+can examine these lines of stratification on the nearest cliff, the
+nearest quarry, the nearest bare headland, in your neighborhood.
+
+But how can this be? If all these stratified rocks are built on the
+floor of the ocean out of material taken _from_ the land, how can we
+by any possibility find such rocks _upon_ the land? In the beds of
+rivers we might indeed expect to see them, but surely nowhere else
+save under ocean waters.
+
+Yet find them we do. Through England, through the two great
+world-continents, they abound on every side. Thousands of miles in
+unbroken succession are composed of such rocks.
+
+Stand with me near the seashore, and let us look around. Those white
+chalk cliffs--they, at least, are not formed of sand or earth. True,
+and the lines of stratification are in them very indistinct, if seen
+at all; yet they too are built up of sediment of a different kind,
+dropping upon ocean's floor. See, however, in the rough sides of
+yonder bluff the markings spoken of, fine lines running alongside of
+one another, sometimes flat, sometimes bent or slanting, but always
+giving the impression of layer piled upon layer. Yet how can one for a
+moment suppose that the ocean-waters ever rose so high?
+
+Stay a moment. Look again at yonder white chalk cliff, and observe a
+little way below the top a singular band of shingles, squeezed into
+the cliff, as it were, with chalk below and earth above.
+
+That is believed to be an old sea-beach. Once upon a time the waters
+of the sea are supposed to have washed those shingles, as now they
+wash the shore near which we stand, and all the white cliff must have
+lain then beneath the ocean.
+
+Geologists were for a long while sorely puzzled to account for these
+old sea-beaches, found high up in the cliffs around our land in many
+different places.
+
+They had at first a theory that the sea must once, in far back ages,
+have been a great deal higher than it is now. But this explanation
+only brought about fresh difficulties. It is quite impossible that the
+level of the sea should be higher in one part of the world than in
+another. If the sea around England were then one or two hundred feet
+higher than it is now, it must have been one or two hundred feet
+higher in every part of the world where the ocean-waters have free
+flow. One is rather puzzled to know where all the water could have
+come from, for such a tremendous additional amount. Besides, in some
+places remains of sea-animals are found in mountain heights, as much
+as two or three thousand feet above the sea-level--as, for instance,
+in Corsica. This very much increases the difficulty of the above
+explanation.
+
+So another theory was started instead, and this is now generally
+supposed to be the true one. What if instead of the whole ocean having
+been higher, parts of the land were lower? England at one time, parts
+of Europe at another time, parts of Asia and America at other times,
+may have slowly sunk beneath the ocean, and after long remaining there
+have slowly risen again.
+
+This is by no means so wild a supposition as it may seem when first
+heard, and as it doubtless did seem when first proposed. For even in
+the present day these movements of the solid crust of our earth are
+going on. The coasts of Sweden and Finland have long been slowly and
+steadily rising out of the sea, so that the waves can no longer reach
+so high upon those shores as in years gone by they used to reach. In
+Greenland, on the contrary, land has long been slowly and steadily
+sinking, so that what used to be the shore now lies under the sea.
+Other such risings and sinkings might be mentioned, as also many more
+in connection with volcanoes and earthquakes, which are neither slow
+nor steady, but sudden and violent.
+
+So it becomes no impossible matter to believe that, in the course of
+ages past, all those wide reaches of our continents and islands, where
+sedimentary rocks are to be found, were each in turn, at one time or
+another, during long periods, beneath the rolling waters of the
+ocean....
+
+       *       *       *       *       *
+
+These built-up rocks are not only called "Stratified," and
+"Sedimentary." They have also the name of _Aqueous Rock_, from the
+Latin word _aqua, water_; because they are believed to have been
+formed by the action of the water.
+
+They have yet another and fourth title, which is, _Fossiliferous
+Rocks_.
+
+Fossils are the hardened remains of animals and vegetables found in
+rocks. They are rarely, if ever, seen in unstratified rocks; but many
+layers of stratified rocks abound in these remains. Whole skeletons as
+well as single bones, whole tree-trunks as well as single leaves, are
+found thus embedded in rock-layers, where in ages past the animal or
+plant died and found a grave. They exist by thousands in many parts of
+the world, varying in size from the huge skeleton of the elephant to
+the tiny shell of the microscopic animalcule.
+
+[Illustration: FOSSIL OF CARBONIFEROUS FERN.]
+
+Fossils differ greatly in kind. Sometimes the entire shell or bone is
+changed into stone, losing all its animal substance, but retaining its
+old outline and its natural markings. Sometimes the fossil is merely
+the hardened impress of the outside of a shell or leaf, which has
+dented its picture on soft clay, and has itself disappeared, while the
+soft clay has become rock, and the indented picture remains fixed
+through after-centuries. Sometimes the fossil is the cast of the
+inside of a shell; the said shell having been filled with soft mud,
+which has taken its exact shape and hardened, while the shell itself
+has vanished. The most complete description of fossil is the first of
+these three kinds. It is wonderfully shown sometimes in fossil wood,
+where all the tiny cells and delicate fibres remain distinctly marked
+as of old, only the whole woody substance has changed into hard stone.
+
+[Illustration: FOOTPRINTS FROM TRIASSIC SANDSTONE OF CONNECTICUT.]
+
+But although the fossil remains of quadrupeds and other land-animals
+are found in large quantities, their number is small compared with the
+enormous number of fossil sea-shells and sea-animals.
+
+[Illustration: FOSSIL FOOTPRINTS.]
+
+Land-animals can, as a rule, have been so preserved, only when they
+have been drowned in ponds or rivers, or mired in bogs and swamps, or
+overtaken by frost, or swept out to sea.
+
+Sea-animals, on the contrary, have been so preserved on land whenever
+that land has been under the sea; and this appears to have been the
+case, at one or another past age, with the greater part of our
+present continents. These fossil remains of sea-animals are
+discovered in all quarters of the world, not only on the seashore but
+also far inland, not only deep down underground but also high up on
+the tops of lofty mountains--a plain proof that over the summits of
+those mountains the ocean must once have rolled, and this not for a
+brief space only, but through long periods of time. And not on the
+mountain-summit only are these fossils known to abound, but sometimes
+in layer below layer of the mountain, from top to bottom, through
+thousands of feet of rock.
+
+[Illustration: FOSSIL SHELLS.]
+
+This may well seem puzzling at first sight. Fossils of sea-creatures
+on a mountain-top are startling enough; yet hardly so startling as the
+thought of fossils _inside_ that mountain. How could they have found
+their way thither?
+
+The difficulty soon vanishes, if once we clearly understand that all
+these thousands of feet of rock were built up slowly, layer after
+layer, when portions of the land lay deep under the sea. Thus _each
+separate layer_ of mud or sand or other material became in its turn
+the _top layer_, and was for the time the floor of the ocean, until
+further droppings of material out of the waters made a fresh layer,
+covering up the one below.
+
+While each layer was thus in succession the top layer of the building,
+and at the same time the floor of the ocean, animals lived and died
+in the ocean, and their remains sank to the bottom, resting upon the
+sediment floor. Thousands of such dead remains disappeared, crumbling
+into fine dust and mingling with the waters, but here and there one
+was caught captive by the half-liquid mud, and was quickly covered and
+preserved from decay. And still the building went on, and still layer
+after layer was placed, till many fossils lay deep down beneath the
+later-formed layers; and when at length, by slow or quick upheaval of
+the ground, this sea-bottom became a mountain, the little fossils were
+buried within the body of that mountain. So wondrously the matter
+appears to have come about.
+
+       *       *       *       *       *
+
+Another difficulty with respect to the stratified rocks has to be
+thought of. All these layers or deposits of gravel, sand, or earth, on
+the floor of the ocean, would naturally be horizontal--that is, would
+lie flat, one upon another. In places the ocean-floor might slant, or
+a crevice or valley or ridge might break the smoothness of the
+deposit. But though the layers might partake of the slant, though the
+valley might have to be filled, though the ridge might have to be
+surmounted, still the general tendency of the waves would be to level
+the dropping deposits into flat layers.
+
+Then how is it that when we examine the strata of rocks in our
+neighborhood, wherever that neighborhood may be, we do not find them
+so arranged? Here, it is true, the lines for a space are nearly
+horizontal, but there, a little way farther on, they are
+perpendicular; here they are bent, and there curved; here they are
+slanting, and there crushed and broken.
+
+This only bears out what has been already said about the Book of
+Geology. It _has_ been bent and disturbed, crushed and broken.
+
+Great powers have been at work in this crust of our earth. Continents
+have been raised, mountains have been upheaved, vast masses of rock
+have been scattered into fragments. Here or there we may find the
+layers arranged as they were first laid down; but far more often we
+discover signs of later disturbance, either slow or sudden, varying
+from a mere quiet tilting to a violent overturn.
+
+[Illustration: EXAMPLE OF DISTURBANCE OF THE EARTH'S LAYERS.]
+
+So the Book of Geology is a torn and disorganized volume, not easy to
+read.
+
+Yet, on the other hand, these very changes which have taken place are
+a help to the geologist.
+
+It may seem at first sight as if we should have an easier task, if the
+strata were all left lying just as they were first formed, in smooth
+level layers, one above another. But if it were so, we could know very
+little about the lower layers.
+
+We might indeed feel sure, as we do now, that the lowest layers were
+the oldest and the top layers the newest, and that any fossils found
+in the lower layers must belong to an age farther back than any
+fossils found in the upper layers.
+
+So much would be clear. And we might dig also and burrow a little way
+down, through a few different kinds of rock, where they were not too
+thick. But that would be all. There our powers would cease.
+
+Now how different. Through the heavings and tiltings of the earth's
+crust, the lower layers are often pushed quite up to the surface, so
+that we are able to examine them and their fossils without the least
+difficulty, and very often without digging underground at all.
+
+You must not suppose that the real order of the rocks is changed by
+these movements, for generally speaking it is not. The lower kinds are
+rarely if ever found placed _over_ the upper kinds; only the ends of
+them are seen peeping out above ground.
+
+It is as if you had a pile of copy-books lying flat one upon another,
+and were to put your finger under the lowest and push it up. All those
+above would be pushed up also, and perhaps they would slip a little
+way down, so that you would have a row of _edges_ showing side by
+side, at very much the same height. The arrangement of the copy-books
+would not be changed, for the lowest would still be the lowest in
+actual position; but a general tilting or upheaval would have taken
+place.
+
+Just such a tilting or upheaval has taken place again and again with
+the rocks forming our earth-crust. The edges of the lower rocks often
+show side by side with those of higher layers.
+
+But geologists know them apart. They are able to tell confidently
+whether such and such a rock, peeping out at the earth's surface,
+belongs really to a lower or a higher kind. For there is a certain
+sort of order followed in the arrangement of rock-layers all over the
+earth, and it is well known that some rocks are never found below some
+other rocks, that certain particular kinds are never placed above
+certain other kinds. Thus it follows that the fossils found in one
+description of rock, must be the fossils of animals which lived and
+died before the animals whose fossil remains are found in another
+neighboring rock, just because this last rock-layer was built upon the
+ocean-floor above and therefore later than the other.
+
+All this is part of the foreign language of geology--part of the
+piecing and arranging of the torn volume. Many mistakes are made; many
+blunders are possible; but the mistakes and blunders are being
+gradually corrected, and certain rules by which to read and understand
+are becoming more and more clear.
+
+It has been already said that unstratified rocks are those which have
+been at some period, whether lately or very long ago, in a liquid
+state from intense heat, and which have since cooled, either quickly
+or slowly, crystallizing as they cooled.
+
+Unstratified Rocks may be divided into two distinct classes.
+
+[Illustration: SECTION OF A LAVA BOMB.]
+
+First.--Volcanic Rocks, such as lava. These have been quickly cooled
+at the surface of the earth, or not far below it.
+
+Secondly.--Plutonic Rocks, such as granite. These have been slowly
+cooled deep down in the earth under heavy pressure.
+
+There is also a class of rocks, called metamorphic rocks, including
+some kinds of marble. These are, strictly speaking, crystalline rocks,
+and yet they are arranged in something like layers. The word
+"metamorphic" simply means "transformed." They are believed to have
+been once stratified rocks, perhaps containing often the remains of
+animals; but intense heat has later transformed them into crystalline
+rocks, and the animal remains have almost or quite vanished.
+
+[Illustration: LAVA-STREAM ON VESUVIUS.]
+
+Just as the different kinds of Stratified Rocks are often called
+Aqueous Rocks, or rocks formed by the action of water--so these
+different kinds of Unstratified Rocks are often called Igneous Rocks,
+or rocks formed by the action of fire--the name being taken from the
+Latin word for fire. The Metamorphic Rocks are sometimes described as
+"Aqueo-igneous," since both water and fire helped in the forming of
+them.
+
+It was at one time believed, as a matter of certainty, that granite
+and such rocks belonged to a period much farther back than the periods
+of the stratified rocks. That is to say, it was supposed that
+fire-action had come first and water-action second; that the fire-made
+rocks were all formed in very early ages, and that only water-made
+rocks still continued to be formed. So the name of Primary Rocks, or
+First Rocks, was given to the granites and other such rocks, and the
+name of Secondary Rocks to all water-built rocks; while those of the
+third class were called Transition Rocks, because they seemed to be a
+kind of link or stepping-stone in the change from the First to the
+Second Rocks.
+
+The chief reason for the general belief that fire-built rocks were
+older than water-built ones was, that the former are as a rule found
+to lie _lower_ than the latter. They form, as it were, the basement of
+the building, while the top-stories are made of water-built rocks.
+
+Many still believe that there is much truth in the thought. It is most
+probable, so far as we are able to judge, that the _first-formed_
+crust of rocks all over the earth was of cooled and crystallized
+material. As these rocks were crumbled and wasted by the ocean,
+materials would have been supplied for the building-up of rocks, layer
+upon layer.
+
+But this is conjecture. We cannot know with any certainty the course
+of events so far back in the past. And geologists are now able to
+state with tolerable confidence that, however old many of the granites
+may be, yet a large amount of the fire-built rocks are no older than
+the water-built rocks which lie over them.
+
+So by many geologists the names of Primary, Transition, and Secondary
+Formations are pretty well given up. It has been proposed to give
+instead to the crystallized rocks of all kinds the name of Underlying
+Rocks (Hypogene Rocks).
+
+But if they really do lie under, how can they possibly be of the same
+age? One would scarcely venture to suppose, in looking at a building,
+that the cellars had not been finished before the upper floors.
+
+True. In the first instance doubtless the cellars were first made,
+then the ground-floor, then the upper stories.
+
+When, however, the house was so built, alterations and improvements
+might be very widely carried on above and below. While one set of
+workmen were engaged in remodelling the roof, another set of workmen
+might be engaged in remodelling the kitchens and first floor, pulling
+down, propping up, and actually rebuilding parts of the lower walls.
+
+This is precisely what the two great fellow-workmen, Fire and Water,
+are ever doing in the crust of our earth. And if it be objected that
+such alterations too widely undertaken might result in slips, cracks,
+and slidings, of ceilings and walls in the upper stories, I can only
+say that such catastrophes _have_ been the result of underground
+alterations in that great building, the earth's crust....
+
+We see therefore clearly that, although the earliest fire-made rocks
+may very likely date farther back than the earliest water-made rocks,
+yet the making of the two kinds has gone on side by side, one below
+and the other above ground, through all ages up to the present moment.
+
+And just as in the present day water continues its busy work above
+ground of pulling down and building up, so also fire continues its
+busy work underground of melting rocks which afterwards cool into new
+forms, and also of shattering and upheaving parts of the earth-crust.
+
+For there can be no doubt that fiery heat does exist as a mighty power
+within our earth, though to what extent we are not able to say.
+
+These two fellow-workers in nature have different modes of working.
+One we can see on all sides, quietly progressing, demolishing land
+patiently bit by bit, building up land steadily grain by grain. The
+other, though more commonly hidden from sight, is fierce and
+tumultuous in character, and shows his power in occasional terrific
+outbursts.
+
+We can scarcely realize what the power is of the imprisoned fiery
+forces underground, though even we are not without some witness of
+their existence. From time to time even our firm land has been felt to
+tremble with a thrill from some far-off shock; and even in our country
+is seen the marvel of scalding water pouring unceasingly from deep
+underground....
+
+Think of the tremendous eruptions of Vesuvius, of Etna, of Hecla, of
+Mauna Loa. Think of whole towns crushed and buried, with their
+thousands of living inhabitants. Think of rivers of glowing lava
+streaming up from regions below ground, and pouring along the surface
+for a distance of forty, fifty, and even sixty miles, as in Iceland
+and Hawaii. Think of red-hot cinders flung from a volcano-crater to a
+height of ten thousand feet. Think of lakes of liquid fire in other
+craters, five hundred to a thousand feet across, huge cauldrons of
+boiling rock. Think of showers of ashes from the furnace below of yet
+another, borne so high aloft as to be carried seven hundred miles
+before they sank to earth again. Think of millions of red-hot stones
+flung out in one eruption of Vesuvius. Think of a mass of rock, one
+hundred cubic yards in size, hurled to a distance of eight miles or
+more out of the crater of Cotopaxi.
+
+[Illustration: HOT WELLS.]
+
+Think also of earthquake-shocks felt through twelve hundred miles of
+country. Think of fierce tremblings and heavings lasting in constant
+succession through days and weeks of terror. Think of hundreds of
+miles of land raised several feet in one great upheaval. Think of the
+earth opening in scores of wide-lipped cracks, to swallow men and
+beasts. Think of hot mud, boiling water, scalding stream, liquid rock,
+bursting from such cracks, or pouring from rents in a mountain-side.
+
+Truly these are signs of a state of things in or below the solid crust
+on which we live, that may make us doubt the absolute security of
+"Mother Earth."
+
+Different explanations have been put forward to explain this seemingly
+fiery state of things underground.
+
+Until lately the belief was widely held that our earth was one huge
+globe of liquid fire, with only a slender cooled crust covering her, a
+few miles in thickness.
+
+This view was supported by the fact that heat is found to increase as
+men descend into the earth. Measurements of such heat-increase have
+been taken, both in mines and in borings for wells. The usual rate is
+about one degree more of heat, of our common thermometer, for every
+fifty or sixty feet of descent. If this were steadily continued, water
+would boil at a depth of eight thousand feet below the surface; iron
+would melt at a depth of twenty-eight miles; while at a depth of forty
+or fifty miles no known substance upon earth could remain solid.
+
+The force of this proof is, however, weakened by the fact that the
+rate at which the heat increases differs very much in different
+places. Also it is now generally supposed that such a tremendous
+furnace of heat--a furnace nearly eight thousand miles in
+diameter--could not fail to break up and melt so slight a covering
+shell.
+
+Many believe, therefore, not that the whole interior of the earth is
+liquid with heat, but that enormous fire-seas or lakes of melted rock
+exist here and there, under or in the earth-crust. From these lakes
+the volcanoes would be fed, and they would be the cause of earthquakes
+and land-upheavals or land-sinkings. There are strong reasons for
+supposing that the earth was once a fiery liquid body, and that she
+has slowly cooled through long ages. Some hold that her centre
+probably grew solid first from tremendous pressure; that her crust
+afterwards became gradually cold; and that between the solid crust and
+the solid inside or "nucleus," a sea of melted rock long existed, the
+remains of which are still to be found in these tremendous fiery
+reservoirs.
+
+The idea accords well with the fact that large numbers of extinct or
+dead volcanoes are scattered through many parts of the earth. If the
+above explanation be the right one, doubtless the fire-seas in the
+crust extended once upon a time beneath such volcanoes, but have since
+died out or smouldered low in those parts.
+
+A somewhat curious calculation has been made, to illustrate the
+different modes of working of these two mighty powers--Fire and Water.
+
+The amount of land swept away each year in mud, and borne to the ocean
+by the River Ganges, was roughly reckoned, and also the amount of land
+believed to have been upheaved several feet in the great Chilian
+earthquake.
+
+It was found that the river, steadily working month by month, would
+require some four hundred years to carry to the sea the same weight of
+material, which in one tremendous effort was upheaved by the fiery
+underground forces.
+
+Yet we must not carry this distinction too far. Fire does not always
+work suddenly, or water slowly; witness the slow rising and sinking of
+land in parts of the earth, continuing through centuries; and witness
+also the effects of great floods and storms.
+
+The crust of the earth is made of rock. But what is rock made of?
+
+Certain leading divisions of rocks have been already considered:
+
+The Water-made Rocks;
+
+The Fire-made Rocks, both Plutonic and Volcanic;
+
+The Water-and-Fire-made Rocks.
+
+The first of these--Water-made Rocks--may be subdivided into three
+classes. These are,--
+
+I. _Flint Rocks_; II. _Clay Rocks_; III. _Lime Rocks_.
+
+This is not a book in which it would be wise to go closely into the
+mineral nature of rocks. Two or three leading thoughts may, however,
+be given.
+
+Does it not seem strange that the hard and solid rocks should be in
+great measure formed of the same substances which form the thin
+invisible air floating around us?
+
+Yet so it is. There is a certain gas called Oxygen Gas. Without that
+gas you could not live many minutes. Banish it from the room in which
+you are sitting, and in a few minutes you will die.
+
+This gas makes up nearly one-quarter by weight of the atmosphere round
+the whole earth.
+
+The same gas plays an important part in the ocean; for more than
+three-quarters of water is _oxygen_.
+
+It plays also an important part in rocks; for about half the material
+of the entire earth's crust is oxygen.
+
+Another chief material in rocks is _silicon_. This makes up
+one-quarter of the crust, leaving only one-quarter to be accounted
+for. Silicon mixed with oxygen makes silica or quartz. There are few
+rocks which have not a large amount of quartz in them. Common flint,
+sandstones, and the sand of our shores, are made of quartz, and
+therefore belong to the first class of Silicious or Flint Rocks.
+Granites and lavas are about one-half quartz. The beautiful stones,
+amethyst, agate, chalcedony, and jasper, are all different kinds of
+quartz.
+
+Another chief material in rocks is a white metal called _aluminium_.
+United to oxygen it becomes alumina, the chief substance in clay.
+Rocks of this kind--such as clays, and also the lovely blue gem,
+sapphire--are called Argillaceous Rocks, from the Latin word for clay,
+and belong to the second class. Such rocks keep fossils well.
+
+Another is _calcium_. United to oxygen and carbonic acid, it makes
+carbonate of lime, the chief substance in limestone; so all limestones
+belong to the third class of Calcareous or Lime Rocks.
+
+Other important materials may be mentioned, such as _magnesium,
+potassium, sodium, iron, carbon, sulphur, hydrogen, chlorine,
+nitrogen_. These, with many more, not so common, make up the remaining
+quarter of the earth-crust.
+
+Carbon plays as important a part in animal and vegetable life as
+silicon in rocks. Carbon is most commonly seen in three distinct
+forms--as charcoal, as black-lead, and as the pure brilliant diamond.
+Carbon united, in a particular proportion, to oxygen, forms carbonic
+acid; and carbonic acid united, in a particular proportion, to lime,
+forms limestone.
+
+_Hydrogen_ united to oxygen forms water. Each of these two gases is
+invisible alone, but when they meet and mingle they form a liquid.
+
+_Nitrogen_ united to oxygen and to a small quantity of carbonic acid
+gas forms our atmosphere.
+
+Rocks of pure flint, pure clay, or pure lime, are rarely or never met
+with. Most rocks are made up of several different substances melted
+together.
+
+       *       *       *       *       *
+
+In the fire-built rocks no remains of animals are found, though in
+water-built rocks they abound. Water-built rocks are sometimes divided
+into two classes--those which only contain occasional animal remains,
+and those which are more or less built up of the skeletons of animals.
+
+[Illustration: AMIBA PRINCEPS, ONE OF THE MANY ORDERS OF THE RHIZOPODA
+CLASS, MAGNIFIED ONE HUNDRED TIMES.]
+
+There are some exceedingly tiny creatures inhabiting the ocean, called
+Rhizopods. They live in minute shells, the largest of which may be
+almost the size of a grain of wheat, but by far the greater number are
+invisible as shells without a microscope, and merely show as fine
+dust. The rhizopods are of different shapes, sometimes round,
+sometimes spiral, sometimes having only one cell, sometimes having
+several cells. In the latter case a separate animal lives in each
+cell. The animal is of the very simplest as well as the smallest kind.
+He has not even a mouth or a stomach but can take in food at any part
+of his body.
+
+[Illustration: RHIZOPODS (MAGNIFIED).]
+
+These rhizopods live in the oceans in enormous numbers. Tens of
+millions are ever coming into existence, living out their tiny lives,
+dying, and sinking to the bottom.
+
+There upon the ocean-floor gather their remains, a heaped-up multitude
+of minute skeletons or shells, layer forming over layer.
+
+It was long suspected that the white chalk cliffs of England were
+built up in some such manner as this through past ages. And now at
+length proof has been found, in the shape of mud dredged up from the
+ocean-bottom--mud entirely composed of countless multitudes of these
+little shells, dropping there by myriads, and becoming slowly joined
+together in one mass.
+
+Just so, it is believed, were the white chalk cliffs built--gradually
+prepared on the ocean-floor, and then slowly or suddenly upheaved, so
+as to become a part of the dry land.
+
+Think what the enormous numbers must have been of tiny living
+creatures, out of whose shells the wide reaches of white chalk cliffs
+have been made. Chalk cliffs and chalk layers extend from Ireland,
+through England and France, as far as to the Crimea. In the south of
+Russia they are said to be six hundred feet thick. Yet one cubic inch
+of chalk is calculated to hold the remains of more than one million
+rhizopods. How many countless millions upon millions must have gone to
+the whole structure! How long must the work of building up have
+lasted!
+
+[Illustration: THREE POLYPS OF CORAL.]
+
+These little shells do not always drop softly and evenly to the
+ocean-floor, to become quietly part of a mass of shells. Sometimes,
+where the ocean is shallow enough for the waves to have power below,
+or where land currents can reach, they are washed about, and thrown
+one against another, and ground into fine powder; and the fine powder
+becomes in time, through different causes, solid rock.
+
+[Illustration: CORAL POLYP.]
+
+Limestone is made in another way also. In the warm waters of the South
+Pacific Ocean there are many islands, large and small, which have
+been formed in a wonderful manner by tiny living workers. The workers
+are soft jelly-like creatures, called polyps, who labor together in
+building up great walls and masses of coral.
+
+[Illustration: CORAL ISLAND.]
+
+[Illustration: YOUNG CORAL POLYP ATTACHED TO A ROCK AND EXPANDED.]
+
+They never carry on their work above the surface of the water, for in
+the air they would die. But the waves break the coral, and heap it up
+above high-water mark, and carry earth and seeds to drop there till at
+length a small low-lying island is formed.
+
+The waves not only heap up broken coral, but they grind the coral into
+fine powder, and from this powder limestone rock is made, just as it
+is from the powdered shells of rhizopods. The material used by the
+polyps in building the coral is chiefly lime, which they have the
+power of gathering out of the water, and the fine coral-powder,
+sinking to the bottom, makes large quantities of hard limestone. Soft
+chalk is rarely, if ever, found near the coral islands.
+
+[Illustration: 1. WHITE CORAL. 2. PORTION OF A BRANCH (MAGNIFIED).]
+
+Limestones are formed in the same manner from the grinding up of other
+sea-shells and fossils, various in kind; the powder becoming gradually
+united into solid rock.
+
+There is yet another way in which limestone is made, quite different
+from all these. Sometimes streams of water have a large quantity of
+lime in them; and these as they flow will drop layers of lime which
+harden into rock. Or a lime-laden spring, making its way through the
+roof of an underground cavern, will leave all kinds of fantastic
+arrangements of limestone wherever its waters can trickle and drip.
+Such a cavern is called a "stalactite cave."
+
+       *       *       *       *       *
+
+So there are different kinds of fossil rock-making. There may be rocks
+made of other materials, with fossil simply buried in them. There may
+be rocks made entirely of fossils, which have gathered in masses as
+they sank to the sea-bottom, and have there become simply and lightly
+joined together. There may be rocks made of the ground-up powder of
+fossils, pressed into a solid substance or united by some other
+substance.
+
+Rocks are also often formed of whole fossils, or stones, or shells,
+bound into one by some natural soft sticky cement, which has gathered
+round them and afterwards grown hard, like the cement which holds
+together the stones in a wall.
+
+The tiny rhizopods (meaning root foot) which have so large a share in
+chalk and limestone making, are among the smallest and simplest known
+kinds of animal life.
+
+There are also some very minute forms of vegetable life, which exist
+in equally vast numbers, called Diatoms. For a long while they were
+believed to be living animals, like the rhizopods. Scientific men are
+now, however, pretty well agreed that they really are only vegetables
+or plants.
+
+The diatoms have each one a tiny shell or shield, not made of lime
+like the rhizopod-shells, but of flint. Some think that common flint
+may be formed of these tiny shells.
+
+Again, there is a kind of rock called Mountain Meal, which is entirely
+made up of the remains of diatoms. Examined under the microscope,
+thousands of minute flint shields of various shapes are seen. This
+rock, or earth, is very abundant in many places, and is sometimes used
+as a polishing powder. In Bohemia there is a layer of it no less than
+fourteen feet thick. Yet so minute are the shells of which it is
+composed, that one square inch of rock is said to contain about four
+thousand millions of them. Each one of these millions is a separate
+distinct fossil....
+
+       *       *       *       *       *
+
+[Illustration: SUCCESSION OF BURIED COAL-GROWTHS AND ERECT
+TREE-STUMPS. SYDNEY, CAPE BRETON.
+
+_a._ Sandstone, _b._ Shales, _c._ Coal-seams, _d._ Bed containing
+Roots and Stumps _in situ_.]
+
+If you examine carefully a piece of coal, you will find, more or less
+clearly, markings like those which are seen in a piece of wood.
+Sometimes they are very distinct indeed. Coal abounds in impressions
+of leaves, ferns, and stems, and fossil remains of plants and
+tree-trunks are found in numbers in coal-seams.
+
+Coal is a vegetable substance. The wide coal-fields of Britain and
+other lands are the _fossil_ remains of vast forests.
+
+Long ages ago, as it seems, broad and luxuriant forests flourished
+over the earth. In many parts generation after generation of trees
+lived and died and decayed, leaving no trace of their existence,
+beyond a little layer of black mould, soon to be carried away by wind
+and water. Coal could only be formed where there were bogs and
+quagmires.
+
+But in bogs and quagmires, and in shallow lakes of low-lying lands,
+there were great gatherings of slowly-decaying vegetable remains,
+trees, plants, and ferns all mingling together. Then after a while the
+low lands would sink and the ocean pouring in would cover them with
+layers of protecting sand or mud; and sometimes the land would rise
+again, and fresh forests would spring into life, only to be in their
+turn overwhelmed anew, and covered by fresh sandy or earthy deposits.
+
+These buried forests lay through the ages following, slowly hardening
+into the black and shining coal, so useful now to man.
+
+The coal is found thus in thin or thick seams, with other rock-layers
+between, telling each its history of centuries long past. In one place
+no less than sixteen such beds of coal are found, one below another,
+each divided from the next above and the next underneath by beds of
+clay or sand or shale. The forests could not have grown in the sea,
+and the earth-layers could not have been formed on land, therefore
+many land-risings and sinkings must have taken place. Each bed
+probably tells the tale of a succession of forests....
+
+       *       *       *       *       *
+
+Before going on to a sketch of the early ages of the Earth's
+history--ages stretching back long long before the time of Adam--it is
+needful to think yet for a little longer about the manner in which
+that history is written, and the way in which it has to be read.
+
+For the record is one difficult to make out, and its style of
+expression is often dark and mysterious. There is scarcely any other
+volume in the great Book of Nature, which the student is so likely to
+misread as this one. It is very needful, therefore, to hold the
+conclusions of geologists with a light grasp, guarding each with a
+"perhaps" or a "may be." Many an imposing edifice has been built, in
+geology, upon a rickety foundation which has speedily given way.
+
+In all ages of the world's history up to the present day, rock-making
+has taken place--fire-made rocks being fashioned underground, and
+water-made rocks being fashioned above ground though under water.
+
+Also in all ages different kinds of rocks have been fashioned side by
+side--limestone in one part of the world, sandstone in another, chalk
+in another, clay in another, and so on. There have, it is true, been
+ages when one kind seems to have been the _chief_ kind--an age of
+limestone, or an age of chalk. But even then there were doubtless more
+rock-buildings going on, though not to so great an extent. On the
+other hand, there may have been ages during which no limestone was
+made, or no chalk, or no clay. As a general rule, however, the various
+sorts of rock-building have probably gone on together. This was not so
+well understood by early geologists as it is now.
+
+The difficulty is often great of disentangling the different strata,
+and saying which was earlier and which later formed.
+
+Still, by close and careful study of the rocks which compose the
+earth's crust, a certain kind of order is found to exist, more or less
+followed out in all parts of the world. _When_ each layer was formed
+in England or in America, the geologist cannot possibly say. He can,
+however, assert, in either place, that a certain mass of rock was
+formed before a certain other mass in that same place, even though
+the two may seem to lie side by side; for he knows that they were so
+placed only by upheaval, and that once upon a time the one lay beneath
+the other.
+
+The geologist can go further. He can often declare that a certain mass
+of rock in America and a certain mass of rock in England, quite
+different in kind, were probably built up at about the same time. How
+long ago that time was he would be rash to attempt to say; but that
+the two belong to the same age he has good reason for supposing.
+
+We find rocks piled upon rocks in a certain order, so that we may
+generally be pretty confident that the lower rocks were first made,
+and the upper rocks the latest built. Further than this, we find in
+all the said layers of water-built rocks signs of past life.
+
+As already stated, much of this life was ocean-life, though not all.
+
+Below the sea, as the rock-layers were being formed, bit by bit, of
+earth dropping from the ocean to the ocean's floor, sea-creatures
+lived out their lives and died by thousands, to sink to that same
+floor. Millions passed away, dissolving and leaving no trace behind;
+but thousands were preserved--shells often, animals sometimes.
+
+Nor was this all. For now and again some part of the sea-bottom was
+upheaved, slowly or quickly, till it became dry land. On this dry land
+animals lived again, and thousands of them, too, died, and their bones
+crumbled into dust. But here and there one was caught in bog or frost,
+and his remains were preserved till, through lapse of ages, they
+turned to stone.
+
+Yet again that land would sink, and over it fresh layers were formed
+by the ocean-waters, with fresh remains of sea-animals buried in with
+the layers of sand or lime; and once more the sea-bottom would rise,
+perhaps then to continue as dry land, until the day when man should
+discover and handle these hidden remains.
+
+Now note a remarkable fact as to these fossils, scattered far and wide
+through the layers of stratified rock.
+
+In the uppermost and latest built rocks the animals found are the
+same, in great measure, as those which now exist upon the earth.
+
+Leaving the uppermost rocks, and examining those which lie a little
+way below, we find a difference. Some are still the same, and others,
+if not quite the same, are very much like what we have now; but here
+and there a creature of a different form appears.
+
+Go deeper still, and the kinds of animals change further. Fewer and
+fewer resemble those which now range the earth; more and more belong
+to other species.
+
+Descend through layer after layer till we come to rocks built in
+earliest ages and not one fossil shall we find precisely the same as
+one animal living now.
+
+So not only are the rocks built in successive order, stratum after
+stratum belonging to age after age in the past, but fossil-remains
+also are found in successive order, kind after kind belonging to past
+age after age.
+
+Although in the first instance the succession of fossils was
+understood by means of the succession of rock-layers, yet in the
+second place the arrangement of rock-layers is made more clear by the
+means of these very fossils.
+
+A geologist, looking at the rocks in America, can say which there were
+first-formed, which second-formed, which third-formed. Also, looking
+at the rocks in England, he can say which there were first-formed,
+second-formed, third-formed. He would, however, find it very
+difficult, if not impossible, to say which among any of the American
+rocks was formed at about the same time as any particular one among
+the English rocks, were it not for the help afforded him by these
+fossils.
+
+Just as the regular succession of rock-strata has been gradually
+learned, so the regular succession of different fossils is becoming
+more and more understood. It is now known that some kinds of fossils
+are always found in the oldest rocks, and in them only; that some
+kinds are always found in the newest rocks, and in them only; that
+some fossils are rarely or never found lower than certain layers; that
+some fossils are rarely or never found higher than certain other
+layers.
+
+So this fossil arrangement is growing into quite a history of the
+past. And a geologist, looking at certain rocks, pushed up from
+underground, in England and in America, can say: "These are very
+different kinds of rocks, it is true, and it would be impossible to
+say how long the building up of the one might have taken place before
+or after the other. But I see that in both these rocks there are
+exactly the same kinds of fossil-remains, differing from those in the
+rocks above and below. I conclude therefore that the two rocks belong
+to about the same great age in the world's past history, when the
+same animals were living upon the earth."
+
+Observing and reasoning thus, geologists have drawn up a general plan
+or order of strata; and the whole of the vast masses of water-built
+rocks throughout the world have been arranged in a regular succession
+of classes, rising step by step from earliest ages up to the present
+time.
+
+[Illustration]
+
+
+
+
+AMERICA THE OLD WORLD
+
+(FROM GEOLOGICAL SKETCHES.)
+
+BY L. AGASSIZ.
+
+
+[Illustration]
+
+First-born among the Continents, though so much later in culture and
+civilization than some of more recent birth, America, so far as her
+physical history is concerned, has been falsely denominated the _New
+World_. Hers was the first dry land lifted out of the waters, hers the
+first shore washed by the ocean that enveloped all the earth beside;
+and while Europe was represented only by islands rising here and there
+above the sea, America already stretched an unbroken line of land from
+Nova Scotia to the Far West.
+
+In the present state of our knowledge, our conclusions respecting the
+beginning of the earth's history, the way in which it took form and
+shape as a distinct, separate planet, must, of course, be very vague
+and hypothetical. Yet the progress of science is so rapidly
+reconstructing the past that we may hope to solve even this problem;
+and to one who looks upon man's appearance upon the earth as the
+crowning work in a succession of creative acts, all of which have had
+relation to his coming in the end, it will not seem strange that he
+should at last be allowed to understand a history which was but the
+introduction to his own existence. It is my belief that not only the
+future, but the past also, is the inheritance of man, and that we
+shall yet conquer our lost birthright.
+
+Even now our knowledge carries us far enough to warrant the assertion
+that there was a time when our earth was in a state of igneous fusion,
+when no ocean bathed it and no atmosphere surrounded it, when no wind
+blew over it and no rain fell upon it, but an intense heat held all
+its materials in solution. In those days the rocks which are now the
+very bones and sinews of our mother Earth--her granites, her
+porphyries, her basalts, her syenites--were melted into a liquid mass.
+As I am writing for the unscientific reader, who may not be familiar
+with the facts through which these inferences have been reached, I
+will answer here a question which, were we talking together, he might
+naturally ask in a somewhat sceptical tone. How do you know that this
+state of things ever existed, and, supposing that the solid materials
+of which our earth consists were ever in a liquid condition, what
+right have you to infer that this condition was caused by the action
+of heat upon them? I answer, Because it is acting upon them still;
+because the earth we tread is but a thin crust floating on a liquid
+sea of molten materials; because the agencies that were at work then
+are at work now, and the present is the logical sequence of the past.
+From artesian wells, from mines, from geysers, from hot springs, a
+mass of facts has been collected, proving incontestably the heated
+condition of all substances at a certain depth below the earth's
+surface; and if we need more positive evidence, we have it in the
+fiery eruptions that even now bear fearful testimony to the molten
+ocean seething within the globe and forcing its way but from time to
+time. The modern progress of Geology has led us by successive and
+perfectly connected steps back to a time when what is now only an
+occasional and rare phenomenon was the normal condition of our earth;
+when the internal fires were enclosed by an envelope so thin that it
+opposed but little resistance to their frequent outbreak, and they
+constantly forced themselves through this crust, pouring out melted
+materials that subsequently cooled and consolidated on its surface. So
+constant were these eruptions, and so slight was the resistance they
+encountered, that some portions of the earlier rock-deposits are
+perforated with numerous chimneys, narrow tunnels as it were, bored by
+the liquid masses that poured out through them and greatly modified
+their first condition.
+
+[Illustration: IDEAL SECTION OF A VOLCANO IN ACTION.]
+
+The question at once suggests itself, How was even this thin crust
+formed? what should cause any solid envelope, however slight and filmy
+when compared to the whole bulk of the globe, to form upon the surface
+of such a liquid mass? At this point of the investigation the
+geologist must appeal to the astronomer; for in this vague and
+nebulous border-land, where the very rocks lose their outlines and
+flow into each other, not yet specialized into definite forms and
+substances,--there the two sciences meet. Astronomy shows us our
+planet thrown off from the central mass of which it once formed a
+part, to move henceforth in an independent orbit of its own. That
+orbit, it tells us, passed through celestial spaces cold enough to
+chill this heated globe, and of course to consolidate it externally.
+We know, from the action of similar causes on a smaller scale and on
+comparatively insignificant objects immediately about us, what must
+have been the effect of this cooling process upon the heated mass of
+the globe. All substances when heated occupy more space than they do
+when cold. Water, which expands when freezing, is the only exception
+to this rule. The first effect of cooling the surface of our planet
+must have been to solidify it, and thus to form a film or crust over
+it. That crust would shrink as the cooling process went on; in
+consequence of the shrinking, wrinkles and folds would arise upon it,
+and here and there, where the tension was too great, cracks and
+fissures would be produced. In proportion as the surface cooled, the
+masses within would be affected by the change of temperature
+outside of them, and would consolidate internally also, the crust
+gradually thickening by this process.
+
+[Illustration: A VOLCANO.]
+
+But there was another element without the globe, equally powerful in
+building it up. Fire and water wrought together in this work, if not
+always harmoniously, at least with equal force and persistency. I have
+said that there was a time when no atmosphere surrounded the earth;
+but one of the first results of the cooling of its crust must have
+been the formation of an atmosphere, with all the phenomena connected
+with it,--the rising of vapors, their condensation into clouds, the
+falling of rains, the gathering of waters upon its surface. Water is a
+very active agent of destruction, but it works over again the
+materials it pulls down or wears away, and builds them up anew in
+other forms. As soon as an ocean washed over the consolidated crust of
+the globe, it would begin to abrade the surfaces upon which it moved,
+gradually loosening and detaching materials, to deposit them again as
+sand or mud or pebbles at its bottom in successive layers, one above
+another. Thus, in analyzing the crust of the globe, we find at once
+two kinds of rocks, the respective work of fire and water: the first
+poured out from the furnaces within, and cooling, as one may see any
+mass of metal cool that is poured out from a smelting-furnace to-day,
+in solid crystalline masses, without any division into separate layers
+or leaves; and the latter in successive beds, one over another, the
+heavier materials below, the lighter above, or sometimes in alternate
+layers, as special causes may have determined successive deposits of
+lighter or heavier materials at some given spot.
+
+There were many well-fought battles between geologists before it was
+understood that these two elements had been equally active in building
+up the crust of the earth. The ground was hotly contested by the
+disciples of the two geological schools, one of which held that the
+solid envelope of the earth was exclusively due to the influence of
+fire, while the other insisted that it had been accumulated wholly
+under the agency of water. This difference of opinion grew up very
+naturally; for the great leaders of the two schools lived in different
+localities, and pursued their investigations over regions where the
+geological phenomena were of an entirely opposite character,--the one
+exhibiting the effect of volcanic eruptions, the other that of
+stratified deposits. It was the old story of the two knights on
+opposite sides of the shield, one swearing that it was made of gold,
+the other that it was made of silver; and almost killing each other
+before they discovered that it was made of both. So prone are men to
+hug their theories and shut their eyes to any antagonistic facts, that
+it is related of Werner, the great leader of the Aqueous school, that
+he was actually on his way to see a geological locality of especial
+interest, but, being told that it confirmed the views of his
+opponents, he turned round and went home again, refusing to see what
+might force him to change his opinions. If the rocks did not confirm
+his theory, so much the worse for the rocks,--he would none of them.
+At last it was found that the two great chemists, fire and water, had
+worked together in the vast laboratory of the globe, and since then
+scientific men have decided to work together also; and if they still
+have a passage at arms occasionally over some doubtful point, yet the
+results of their investigations are ever drawing them nearer to each
+other,--since men who study truth, when they reach their goal, must
+always meet at last on common ground.
+
+The rocks formed under the influence of heat are called, in geological
+language, the Igneous, or, as some naturalists have named them, the
+Plutonic rocks, alluding to their fiery origin, while the others have
+been called Aqueous or Neptunic rocks, in reference to their origin
+under the agency of water. A simpler term, however, quite as
+distinctive, and more descriptive of their structure, is that of the
+stratified and massive or unstratified rocks. We shall see hereafter
+how the relative position of these two classes of rocks and their
+action upon each other enable us to determine the chronology of the
+earth, to compare the age of her mountains, and, if we have no
+standard by which to estimate the positive duration of her continents,
+to say at least which was the first-born among them, and how their
+characteristic features have been successfully worked out. I am aware
+that many of these inferences, drawn from what is called "the
+geological record," must seem to be the work of the imagination. In a
+certain sense this is true,--for imagination, chastened by correct
+observation, is our best guide in the study of Nature. We are too apt
+to associate the exercise of this faculty with works of fiction, while
+it is in fact the keenest detective of truth.
+
+[Illustration: DIKES.]
+
+Besides the stratified and massive rocks, there is still a third set,
+produced by the contact of these two, and called, in consequence of
+the changes thus brought about, the Metamorphic rocks. The effect of
+heat upon clay is to bake it into slate; limestone under the influence
+of heat becomes quick-lime, or, if subjected afterwards to the action
+of water, it is changed to mortar; sand under the same agency is
+changed to a coarse kind of glass. Suppose, then, that a volcanic
+eruption takes place in a region of the earth's surface where
+successive layers of limestone, of clay, and of sandstone, have been
+previously deposited by the action of water. If such an eruption has
+force enough to break through these beds, the hot, melted masses will
+pour out through the rent, flow over its edges, and fill all the
+lesser cracks and fissures produced by such a disturbance. What will
+be the effect upon the stratified rocks? Wherever these liquid masses,
+melted by a heat more intense than can be produced by any artificial
+means, have flowed over them or cooled in immediate contact with them,
+the clays will be changed to slate, the limestone will have assumed a
+character more like marble, while the sandstone will be vitrified.
+This is exactly what has been found to be the case, wherever the
+stratified rocks have been penetrated by the melted masses from
+beneath. They have been themselves partially melted by the contact,
+and when they have cooled again, their stratification, though still
+perceptible, has been partly obliterated, and their substance changed.
+Such effects may often be traced in dikes, which are only the cracks
+in rocks filled by materials poured into them at some period of
+eruption when the melted masses within the earth were thrown out and
+flowed like water into any inequality or depression of the surface
+around. The walls enclosing such a dike are often found to be
+completely altered by contact with its burning contents, and to have
+assumed a character quite different from the rocks of which they make
+a part; while the mass itself which fills the fissure shows by the
+character of its crystallization that it has cooled more quickly on
+the outside, where it meets the walls, than at the centre.
+
+The first two great classes of rocks, the unstratified and stratified
+rocks, represent different epochs in the world's physical history: the
+former mark its revolutions, while the latter chronicle its periods of
+rest. All mountains and mountain-chains have been upheaved by great
+convulsions of the globe, which rent asunder the surface of the earth,
+destroyed the animals and plants living upon it at the time, and were
+then succeeded by long intervals of repose, when all things returned
+to their accustomed order, ocean and river deposited fresh beds in
+uninterrupted succession, the accumulation of materials went on as
+before, a new set of animals and plants were introduced, and a time of
+building up and renewing followed the time of destruction. These
+periods of revolution are naturally more difficult to decipher than
+the periods of rest; for they have so torn and shattered the beds they
+uplifted, disturbing them from their natural relations to each other,
+that it is not easy to reconstruct the parts and give them coherence
+and completeness again. But within the last half-century this work has
+been accomplished in many parts of the world with an amazing degree of
+accuracy, considering the disconnected character of the phenomena to
+be studied; and I think I shall be able to convince my readers that
+the modern results of geological investigation are perfectly sound
+logical inferences from well-established facts. In this, as in so many
+other things, we are but "children of a larger growth." The world is
+the geologist's great puzzle-box; he stands before it like the child
+to whom the separate pieces of his puzzle remain a mystery till he
+detects their relation and sees where they fit, and then his fragments
+grow at once into a connected picture beneath his hand....
+
+When geologists first turned their attention to the physical history
+of the earth, they saw at once certain great features which they took
+to be the skeleton and basis of the whole structure. They saw the
+great masses of granite forming the mountains and mountain-chains,
+with the stratified rocks resting against their slopes; and they
+assumed that granite was the first primary agent, and that all
+stratified rocks must be of a later formation. Although this involved
+a partial error, as we shall see hereafter when we trace the upheavals
+of granite even into comparatively modern periods, yet it held an
+important geological truth also; for, though granite formations are by
+no means limited to those early periods, they are nevertheless very
+characteristic of them, and are indeed the foundation-stones on which
+the physical history of the globe is built.
+
+Starting from this landmark, the earlier geologists divided the
+world's history into three periods. As the historian recognizes
+Ancient History, the Middle Ages, and Modern History as distinct
+phases in the growth of the human race, so they distinguished between
+what they called the Primary period, when, as they believed, no life
+stirred on the surface of the earth; the Secondary or middle period,
+when animals and plants were introduced, and the land began to assume
+continental proportions; and the Tertiary period, or comparatively
+modern geological times, when the physical features of the earth as
+well as its inhabitants were approaching more nearly to the present
+condition of things. But as their investigations proceeded, they found
+that every one of these great ages of the world's history was divided
+into numerous lesser epochs, each of which had been characterized by a
+peculiar set of animals and plants, and had been closed by some great
+physical convulsion, disturbing and displacing the materials
+accumulated during such a period of rest.
+
+The further study of these subordinate periods showed that what had
+been called Primary formations, namely, the volcanic or Plutonic rocks
+formerly believed to be confined to the first geological ages,
+belonged to all the periods, successive eruptions having taken place
+at all times, pouring up through the accumulated deposits, penetrating
+and injecting their cracks, fissures, and inequalities, as well as
+throwing out large masses on the surface. Up to our own day there has
+never been a period when such eruptions have not taken place, though
+they have been constantly diminishing in frequency and extent. In
+consequence of this discovery, that rocks of igneous character were by
+no means exclusively characteristic of the earliest times, they are
+now classified together upon very different grounds from those on
+which geologists first united them; though, as the name _Primary_ was
+long retained, we still find it applied to them, even in geological
+works of quite recent date. This defect of nomenclature is to be
+regretted, as likely to mislead the student, because it seems to refer
+to time; whereas it no longer signifies the age of the rocks, but
+simply their character. The name Plutonic or Massive rocks is,
+however, now almost universally substituted for that of Primary.
+
+A wide field of investigation still remains to be explored by the
+chemist and the geologist together, in the mineralogical character of
+the Plutonic rocks, which differs greatly in the different periods.
+The earlier eruptions seem to have been chiefly granitic, though this
+must not be understood in too wide a sense, since there are granite
+formations even as late as the Tertiary period; those of the middle
+periods were mostly porphyries and basalts; while in the more recent
+ones, lavas predominate. We have as yet no clew to the laws by which
+this distribution of volcanic elements in the formation of the earth
+is regulated; but there is found to be a difference in the crystals of
+the Plutonic rocks belonging to different ages, which, when fully
+understood may enable us to determine the age of any Plutonic rock by
+its mode of crystallization; so that the mineralogist will as readily
+tell you by its crystals whether a bit of stone of igneous origin
+belongs to this or that period of the world's history, as the
+palæontologist will tell you by its fossils whether a piece of rock
+of aqueous origin belongs to the Silurian or Devonian or Carboniferous
+deposits.
+
+Although subsequent investigations have multiplied so extensively not
+only the number of geological periods, but also the successive
+creations that have characterized them, yet the first general division
+into three great eras was nevertheless founded upon a broad and true
+generalization. In the first stratified rocks in which any organic
+remains are found, the highest animals are fishes, and the highest
+plants are cryptogams; in the middle periods reptiles come in,
+accompanied by fern and moss forests; in later times quadrupeds are
+introduced, with a dicotyledonous vegetation. So closely does the
+march of animal and vegetable life keep pace with the material
+progress of the world, that we may well consider these three
+divisions, included under the first general classification of its
+physical history, as the three Ages of Nature; the more important
+epochs which subdivide them may be compared to so many great
+dynasties, while the lesser periods are the separate reigns contained
+therein. Of such epochs there are ten, well known to geologists; of
+the lesser periods about sixty are already distinguished, while many
+more loom up from the dim regions of the past, just discerned by the
+eye of science, though their history is not yet unravelled.
+
+Before proceeding further, I will enumerate the geological epochs in
+their succession, confining myself, however, to such as are perfectly
+well established, without alluding to those of which the limits are
+less definitely determined, and which are still subject to doubts and
+discussions among geologists. As I do not propose to make here any
+treatise of Geology, but simply to place before my readers some
+pictures of the old world, with the animals and plants that have
+inhabited it at various times, I shall avoid, as far as possible, all
+debatable ground, and confine myself to those parts of my subject
+which are best known, and can therefore be more clearly presented.
+
+[Illustration: FOSSIL SCORPION.--SILURIAN PERIOD.]
+
+First, we have the Azoic period, _devoid of life_, as its name
+signifies,--namely, the earliest stratified deposits upon the heated
+film forming the first solid surface of the earth, in which no trace
+of living thing has ever been found. Next comes the Silurian period,
+when the crust of the earth had thickened and cooled sufficiently to
+render the existence of animals and plants upon it possible, and when
+the atmospheric conditions necessary to their maintenance were already
+established. Many of the names given to these periods are by no means
+significant of their character, but are merely the result of accident:
+as, for instance, that of Silurian, given by Sir Roderick Murchison to
+this set of beds, because he first studied them in that part of Wales
+occupied by the ancient tribe of the Silures. The next period, the
+Devonian, was for a similar reason named after the country of
+Devonshire in England, where it was first investigated. Upon this
+follows the Carboniferous period, with the immense deposits of coal
+from which it derives its name. Then comes the Permian period, named,
+again, from local circumstances, the first investigation of its
+deposits having taken place in the province of Permia in Russia. Next
+in succession we have the Triassic period, so called from the trio of
+rocks, the red sandstone, Muschel Kalk (shell-limestone), and Keuper
+(clay), most frequently combined in its formations; the Jurassic, so
+amply illustrated in the chain of the Jura, where geologists first
+found the clew to its history; and the Cretaceous period, to which the
+chalk cliffs of England and all the extensive chalk deposits belong.
+Upon these follow the so-called Tertiary formations, divided into
+three periods, all of which have received most characteristic names in
+this epoch of the world's history we see the first approach to a
+condition of things resembling that now prevailing, and Sir Charles
+Lyell has most fitly named its three divisions, the Eocene, Miocene,
+and Pliocene. The termination of the three words is made from the
+Greek word _Kainos_, recent; while _Eos_ signifies dawn, _Meion_ less,
+and _Pleion_ more. Thus Eocene indicates the dawn of recent species,
+Pliocene their increase, while Miocene, the intermediate term, means
+less recent. Above these deposits comes what has been called in
+science the present period,--_the modern times_ of the geologist,--that
+period to which man himself belongs, and since the beginning of which,
+though its duration be counted by hundreds of thousands of years,
+there has been no alteration in the general configuration of the
+earth, consequently no important modification of its climatic
+conditions, and no change in the animals and plants inhabiting it.
+
+[Illustration: CRUSTACEA.--DEVONIAN PERIOD.]
+
+[Illustration: FISH OF THE DEVONIAN PERIOD.]
+
+[Illustration: FISH OF THE CARBONIFEROUS PERIOD.]
+
+[Illustration: FOSSIL VEGETATION OF CARBONIFEROUS PERIOD.]
+
+[Illustration: FISH OF THE PERMIAN PERIOD.]
+
+I have spoken of the first of these periods, the Azoic, as having
+been absolutely devoid of life, and I believe this statement to be
+strictly true; but I ought to add that there is a difference of
+opinion among geologists upon this point, many believing that the
+first surface of our globe may have been inhabited by living beings,
+but that all traces of their existence have been obliterated by the
+eruptions of melted materials, which not only altered the character of
+those earliest stratified rocks, but destroyed all the organic remains
+contained in them. It will be my object to show, not only that the
+absence of the climatic and atmospheric conditions essential to
+organic life, as we understand it, must have rendered the previous
+existence of any living beings impossible, but also that the
+completeness of the Animal Kingdom in those deposits where we first
+find organic remains, its intelligible and coherent connections with
+the successive creations of all geological times and with the animals
+now living, afford the strongest internal evidence that we have indeed
+found in the lower Silurian formations, immediately following the
+Azoic, the beginning of life upon earth. When a story seems to us
+complete and consistent from the beginning to the end, we shall not
+seek for a first chapter, even though the copy in which we have read
+it be so torn and defaced as to suggest the idea that some portion of
+it may have been lost. The unity of the work, as a whole, is an
+incontestable proof that we possess it in its original integrity. The
+validity of this argument will be recognized, perhaps, only by those
+naturalists to whom the Animal Kingdom has begun to appear as a
+connected whole. For those who do not see order in Nature it can have
+no value.
+
+[Illustration: FOSSILS OF TRIASSIC VEGETATION.]
+
+[Illustration: BIRD OF THE JURASSIC PERIOD.(The Oldest Bird.)]
+
+[Illustration: SKELETON OF BIRD OF THE CRETACEOUS PERIOD.]
+
+[Illustration: SKELETON OF ANIMAL OF THE EOCENE PERIOD.]
+
+For a table containing the geological periods in their succession, I
+would refer to any modern text-book of Geology, or to an article in
+the _Atlantic Monthly_ for March, 1862, upon "Methods of Study in
+Natural History," where they are given in connection with the order of
+introduction of animals upon earth.
+
+Were these sets of rocks found always in the regular sequence in which
+I have enumerated them, their relative age would be easily
+determined, for their superposition would tell the whole story: the
+lowest would, of course, be the oldest, and we might follow without
+difficulty the ascending series, till we reached the youngest and
+uppermost deposits. But their succession has been broken up by
+frequent and violent alterations in the configuration of the globe.
+Land and water have changed their level,--islands have been
+transformed to continents,--sea-bottoms have become dry land, and dry
+land has sunk to form sea-bottoms,--Alps and Himalayas, Pyrenees and
+Apennines, Alleghanies and Rocky Mountains, have had their stormy
+birthdays since many of these beds have been piled one above another,
+and there are but few spots on the earth's surface where any number of
+them may be found in their original order and natural position. When
+we remember that Europe, which lies before us on the map as a
+continent, was once an archipelago of islands,--that, where the
+Pyrenees raise their rocky barrier between France and Spain, the
+waters of the Mediterranean and Atlantic met,--that, where the British
+Channel flows, dry land united England and France, and Nature in those
+days made one country of the lands parted since by enmities deeper
+than the waters that run between,--when we remember, in short, all the
+fearful convulsions that have torn asunder the surface of the earth,
+as if her rocky record had indeed been written on paper, we shall find
+a new evidence of the intellectual unity which holds together the
+whole physical history of the globe in the fact that through all the
+storms of time the investigator is able to trace one unbroken thread
+of thought from the beginning to the present hour.
+
+[Illustration: SKELETON OF ANIMAL OF THE MIOCENE PERIOD.]
+
+[Illustration: SKELETON OF ANIMAL OF THE PLIOCENE PERIOD.]
+
+The tree is known by its fruits,--and the fruits of chance are
+incoherence, incompleteness, unsteadiness, the stammering utterance of
+blind, unreasoning force. A coherence that binds all the geological
+ages in one chain, a stability of purpose that completes in the beings
+born to-day an intention expressed in the first creatures that swam in
+the Silurian ocean or crept upon its shores, a steadfastness of
+thought, practically recognized by man, if not acknowledged by him,
+whenever he traces the intelligent connection between the facts of
+Nature and combines them into what he is pleased to call his system of
+Geology, or Zoölogy, or Botany,--these things are not the fruits of
+chance or of an unreasoning force, but the legitimate results of
+intellectual power. There is a singular lack of logic, as it seems to
+me, in the views of the materialistic naturalists. While they consider
+classification, or, in other words, their expression of the relations
+between animals or between physical facts of any kind, as the work of
+their intelligence, they believe the relations themselves to be the
+work of physical causes. The more direct inference surely is, that, if
+it requires an intelligent mind to recognize them, it must have
+required an intelligent mind to establish them. These relations
+existed before man was created; they have existed ever since the
+beginning of time; hence, what we call the classification of facts is
+not the work of his mind in any direct original sense, but the
+recognition of an intelligent action prior to his own existence.
+
+There is, perhaps, no part of the world, certainly none familiar to
+science, where the early geological periods can be studied with so
+much ease and precision as in the United States. Along their northern
+borders, between Canada and the United States, there runs the low line
+of hills known as the Laurentian Hills. Insignificant in height,
+nowhere rising more than fifteen hundred or two thousand feet above
+the level of the sea, these are nevertheless the first mountains that
+broke the uniform level of the earth's surface and lifted themselves
+above the waters. Their low stature, as compared with that of other
+more lofty mountain-ranges, is in accordance with an invariable rule,
+by which the relative age of mountains may be estimated. The oldest
+mountains are the lowest, while the younger and more recent ones tower
+above their elders, and are usually more torn and dislocated also.
+This is easily understood, when we remember that all mountains and
+mountain-chains are the result of upheavals, and that the violence of
+the outbreak must have been in proportion to the strength of the
+resistance. When the crust of the earth was so thin that the heated
+masses within easily broke through it, they were not thrown to so
+great a height, and formed comparatively low elevations, such as the
+Canadian hills or the mountains of Bretagne and Wales. But in later
+times, when young, vigorous giants, such as the Alps, the Himalayas,
+or, later still, the Rocky Mountains, forced their way out from their
+fiery prison-house, the crust of the earth was much thicker, and
+fearful indeed must have been the convulsions which attended their
+exit.
+
+[Illustration: A PHYSICAL MAP OF THE UNITED STATES.]
+
+The Laurentian Hills form, then, a granite range, stretching from
+Eastern Canada to the Upper Mississippi, and immediately along its
+base are gathered the Azoic deposits, the first stratified beds, in
+which the absence of life need not surprise us, since they were
+formed beneath a heated ocean. As well might we expect to find the
+remains of fish or shells or crabs at the bottom of geysers or of
+boiling springs, as on those early shores bathed by an ocean of which
+the heat must have been so intense. Although, from the condition in
+which we find it, this first granite range has evidently never been
+disturbed by any violent convulsion since its first upheaval, yet
+there has been a gradual rising of that part of the continent; for the
+Azoic beds do not lie horizontally along the base of the Laurentian
+Hills in the position in which they must originally have been
+deposited, but are lifted and rest against their slopes. They have
+been more or less dislocated in this process, and are greatly
+metamorphized by the intense heat to which they must have been
+exposed. Indeed, all the oldest stratified rocks have been baked by
+the prolonged action of heat.
+
+It may be asked how the materials for those first stratified deposits
+were provided. In later times, when an abundant and various soil
+covered the earth, when every river brought down to the ocean, not
+only its yearly tribute of mud or clay or lime, but the débris of
+animals and plants that lived and died in its waters or along its
+banks, when every lake and pond deposited at its bottom in successive
+layers the lighter or heavier materials floating in its waters and
+settling gradually beneath them, the process by which stratified
+materials are collected and gradually harden into rock is more easily
+understood. But when the solid surface of the earth was only just
+beginning to form, it would seem that the floating matter in the sea
+can hardly have been in sufficient quantity to form any extensive
+deposits. No doubt there was some abrasion even of that first crust;
+but the more abundant source of the earliest stratification is to be
+found in the submarine volcanoes that poured their liquid streams into
+the first ocean. At what rate these materials would be distributed and
+precipitated in regular strata it is impossible to determine; but that
+volcanic materials were so deposited in layers is evident from the
+relative position of the earliest rocks. I have already spoken of the
+innumerable chimneys perforating the Azoic beds, narrow outlets of
+Plutonic rock, protruding through the earliest strata. Not only are
+such funnels filled with the crystalline mass of granite that flowed
+through them in a liquid state, but it has often poured over their
+sides, mingling with the stratified beds around. In the present state
+of our knowledge, we can explain such appearances only by supposing
+that the heated materials within the earth's crust poured out
+frequently, meeting little resistance,--that they then scattered and
+were precipitated in the ocean around, settling in successive strata
+at its bottom,--that through such strata the heated masses within
+continued to pour again and again, forming for themselves the
+chimney-like outlets above mentioned.
+
+Such, then, was the earliest American land,--a long, narrow island,
+almost continental in its proportions, since it stretched from the
+eastern borders of Canada nearly to the point where now the base of
+the Rocky Mountains meets the plain of the Mississippi Valley. We may
+still walk along its ridge and know that we tread upon the ancient
+granite that first divided the waters into a northern and southern
+ocean; and if our imaginations will carry us so far, we may look down
+toward its base and fancy how the sea washed against this earliest
+shore of a lifeless world. This is no romance, but the bald, simple
+truth; for the fact that this granite band was lifted out of the
+waters so early in the history of the world, and has not since been
+submerged, has, of course, prevented any subsequent deposits from
+forming above it. And this is true of all the northern part of the
+United States. It has been lifted gradually, the beds deposited in one
+period being subsequently raised, and forming a shore along which
+those of the succeeding one collected, so that we have their whole
+sequence before us. In regions where all the geological deposits
+(Silurian, Devonian, carboniferous, permian, triassic, etc.) are piled
+one upon another, and we can get a glimpse of their internal relations
+only where some rent has laid them open, or where their ragged edges,
+worn away by the abrading action of external influences, expose to
+view their successive layers, it must, of course, be more difficult to
+follow their connection. For this reason the American continent offers
+facilities to the geologist denied to him in the so-called Old World,
+where the earlier deposits are comparatively hidden, and the broken
+character of the land, intersected by mountains in every direction,
+renders his investigation still more difficult. Of course, when I
+speak of the geological deposits as so completely unveiled to us here,
+I do not forget the sheet of drift which covers the continent from
+north to south, and which we shall discuss hereafter, when I reach
+that part of my subject. But the drift is only a superficial and
+recent addition to the soil, resting loosely above the other
+geological deposits, and arising, as we shall see, from very different
+causes.
+
+In this article I have intended to limit myself to a general sketch of
+the formation of the Laurentian Hills with the Azoic stratified beds
+resting against them. In the Silurian epoch following the Azoic we
+have the first beach on which any life stirred; it extended along the
+base of the Azoic beds, widening by its extensive deposits the narrow
+strip of land already upheaved. I propose ... to invite my readers to
+a stroll with me along that beach.
+
+With what interest do we look upon any relic of early human history!
+The monument that tells of a civilization whose hieroglyphic records
+we cannot even decipher, the slightest trace of a nation that vanished
+and left no sign of its life except the rough tools and utensils
+buried in the old site of its towns or villages, arouses our
+imagination and excites our curiosity. Men gaze with awe at the
+inscription on an ancient Egyptian or Assyrian stone; they hold with
+reverential touch the yellow parchment-roll whose dim, defaced
+characters record the meagre learning of a buried nationality; and the
+announcement, that for centuries the tropical forests of Central
+America have hidden within their tangled growth the ruined homes and
+temples of a past race, stirs the civilized world with a strange, deep
+wonder.
+
+To me it seems, that to look on the first land that was ever lifted
+above the waste of waters, to follow the shore where the earliest
+animals and plants were created when the thought of God first
+expressed itself in organic forms, to hold in one's hand a bit of
+stone from an old sea-beach, hardened into rock thousands of
+centuries ago, and studded with the beings that once crept upon its
+surface or were stranded there by some retreating wave, is even of
+deeper interest to men than the relies of their own race, for these
+things tell more directly of the thoughts and creative acts of God.
+
+Standing in the neighborhood of Whitehall, near Lake George, one may
+look along such a seashore, and see it stretching westward and sloping
+gently southward as far as the eye can reach. It must have had a very
+gradual slope, and the waters must have been very shallow; for at that
+time no great mountains had been uplifted, and deep oceans are always
+the concomitants of lofty heights. We do not, however, judge of this
+by inference merely; we have an evidence of the shallowness of the sea
+in those days in the character of the shells found in the Silurian
+deposits, which shows that they belonged in shoal waters.
+
+Indeed, the fossil remains of all times tell us almost as much of the
+physical condition of the world at different epochs as they do of its
+animal and vegetable population. When Robinson Crusoe first caught
+sight of the footprint on the sand, he saw in it more than the mere
+footprint, for it spoke to him of the presence of men on his desert
+island. We walk on the old geological shores, like Crusoe along his
+beach, and the footprints we find there tell us, too, more than we
+actually see in them. The crust of our earth is a great cemetery,
+where the rocks are tombstones on which the buried dead have written
+their own epitaphs. They tell us not only who they were and when and
+where they lived, but much also of the circumstances under which they
+lived. We ascertain the prevalence of certain physical conditions at
+special epochs by the presence of animals and plants whose existence
+and maintenance required such a state of things, more than by any
+positive knowledge respecting it. Where we find the remains of
+quadrupeds corresponding to our ruminating animals, we infer not only
+land, but grassy meadows also, and an extensive vegetation; where we
+find none but marine animals, we know the ocean must have covered the
+earth; the remains of large reptiles, representing, though in gigantic
+size, the half aquatic, half terrestrial reptiles of our own period,
+indicate to us the existence of spreading marshes still soaked by the
+retreating waters; while the traces of such animals as live now in
+sand and shoal waters, or in mud, speak to us of shelving sandy
+beaches and of mud-flats. The eye of the Trilobite tells us that the
+sun shone on the old beach where he lived; for there is nothing in
+nature without a purpose, and when so complicated an organ was made to
+receive the light, there must have been light to enter it. The immense
+vegetable deposits in the Carboniferous period announce the
+introduction of an extensive terrestrial vegetation; and the
+impressions left by the wood and leaves of the trees show that these
+first forests must have grown in a damp soil and a moist atmosphere.
+In short, all the remains of animals and plants hidden in the rocks
+have something to tell of the climatic conditions and the general
+circumstances under which they lived, and the study of fossils is to
+the naturalist a thermometer by which he reads the variations of
+temperature in past times, a plummet by which he sounds the depths of
+the ancient oceans,--a register, in fact, of all the important
+physical changes the earth has undergone.
+
+But although the animals of the early geological deposits indicate
+shallow seas by their similarity to our shoal-water animals, it must
+not be supposed that they are by any means the same. On the contrary,
+the old shells, crustacea, corals, etc., represent types which have
+existed in all times with the same essential structural elements, but
+under different specific forms in the several geological periods. And
+here it may not be amiss to say something of what are called by
+naturalists _representative types_.
+
+The statement that different sets of animals and plants have
+characterized the successive epochs is often understood as indicating
+a difference of another kind than that which distinguishes animals now
+living in different parts of the world. This is a mistake. There are
+so-called representative types all over the globe, united to each
+other by structural relations and separated by specific differences of
+the same kind as those that unite and separate animals of different
+geological periods. Take, for instance, mud-flats or sandy shores in
+the same latitudes of Europe and America; we find living on each,
+animals of the same structural character and of the same general
+appearance, but with certain specific differences, as of color, size,
+external appendages, etc. They represent each other on the two
+continents. The American wolves, foxes, bears, rabbits, are not the
+same as the European, but those of one continent are as true to their
+respective types as those of the other; under a somewhat different
+aspect they represent the same groups of animals. In certain
+latitudes, or under conditions of nearer proximity, these differences
+may be less marked. It is well known that there is a great monotony
+of type, not only among animals and plants, but in the human races
+also, throughout the Arctic regions; and some animals characteristic
+of the high North reappear under such identical forms in the
+neighborhood of the snow-fields in lofty mountains, that to trace the
+difference between the ptarmigans, rabbits, and other gnawing animals
+of the Alps, for instance, and those of the Arctics, is among the most
+difficult problems of modern science.
+
+And so it is also with the animated world of past ages; in similar
+deposits of sand, mud, or lime, in adjoining regions of the same
+geological age, identical remains of animals and plants may be found;
+while at greater distances, but under similar circumstances,
+representative species may occur. In very remote regions, however,
+whether the circumstances be similar or dissimilar, the general aspect
+of the organic world differs greatly, remoteness in space being thus
+in some measure an indication of the degree of affinity between
+different faunæ. In deposits of different geological periods
+immediately following each other, we sometimes find remains of animals
+and plants so closely allied to those of earlier or later periods that
+at first sight the specific differences are hardly discernible. The
+difficulty of solving these questions, and of appreciating correctly
+the differences and similarities between such closely allied
+organisms, explains the antagonistic views of many naturalists
+respecting the range of existence of animals, during longer or shorter
+geological periods; and the superficial way in which discussions
+concerning the transition of species are carried on, is mainly owing
+to an ignorance of the conditions above alluded to. My own personal
+observation and experience in these matters have led me to the
+conviction that every geological period has had its own
+representatives, and that no single species has been repeated in
+successive ages.
+
+The laws regulating the geographical distribution of animals, and
+their combination into distinct zoölogical provinces called faunæ,
+with definite limits, are very imperfectly understood as yet; but so
+closely are all things linked together from the beginning that I am
+convinced we shall never find the clew to their meaning till we carry
+on our investigations in the past and the present simultaneously. The
+same principle according to which animal and vegetable life is
+distributed over the surface of the earth now, prevailed in the
+earliest geological periods. The geological deposits of all times have
+had their characteristic faunæ under various zones, their zoölogical
+provinces presenting special combinations of animal and vegetable life
+over certain regions, and their representative types reproducing in
+different countries, but under similar latitudes, the same groups with
+specific differences.
+
+Of course, the nearer we approach the beginning of organic life, the
+less marked do we find the differences to be, and for a very obvious
+reason. The inequalities of the earth's surface, her mountain-barriers
+protecting whole continents from the Arctic winds, her open plains
+exposing others to the full force of the polar blasts, her snug
+valleys and her lofty heights, her tablelands and rolling prairies,
+her river-systems and her dry deserts, her cold ocean-currents pouring
+down from the high North on some of her shores, while warm ones from
+tropical seas carry their softer influence to others,--in short, all
+the contrasts in the external configuration of the globe, with the
+physical conditions attendant upon them, are naturally accompanied by
+a corresponding variety in animal and vegetable life.
+
+But in the Silurian age, when there were no elevations higher than the
+Canadian hills, when water covered the face of the earth, with the
+exception of a few isolated portions lifted above the almost universal
+ocean, how monotonous must have been the conditions of life! And what
+should we expect to find on those first shores? If we are walking on a
+sea-beach to-day, we do not look for animals that haunt the forests or
+roam over the open plains, or for those that live in sheltered valleys
+or in inland regions or on mountain-heights. We look for Shells, for
+Mussels and Barnacles, for Crabs, for Shrimps, for Marine Worms, for
+Star-Fishes and Sea-Urchins, and we may find here and there a fish
+stranded on the sand or tangled in the seaweed.
+
+[Illustration]
+
+
+
+
+SOME RECORDS OF THE ROCKS
+
+(FROM A FIRST BOOK IN GEOLOGY.)
+
+BY N.S. SHALER, S.D.[1]
+
+[Footnote 1: Copyright, 1884, by N.S. Shaler.]
+
+[Illustration]
+
+The geologist cannot find his way back in the record of the great
+stone book, to the far-off day when life began. The various changes
+that come over rocks from the action of heat, of water, and of
+pressure, have slowly modified these ancient beds, so that they no
+longer preserve the frames of the animals that were buried in them.
+
+These old rocks, which are so changed that we cannot any longer make
+sure that any animals lived in them, are called the "archæan," which
+is Greek for ancient. They were probably mud and sand and limestone
+when first made, but they have been changed to mica schists, gneiss,
+granite, marble, and other crystalline rocks. When any rock becomes
+crystalline, the fossils dissolve and disappear, as coins lose their
+stamp and form when they are melted in the jeweller's gold-pot.
+
+These ancient rocks that lie deepest in the earth are very thick, and
+must have taken a great time in building; great continents must have
+been worn down by rain and waves in order to supply the waste out of
+which they were made. It is tolerably certain that they took as much
+time during their making as has been required for all the other times
+since they were formed. During the vast ages of this archæan the life
+of our earth began to be. We first find many certain evidences of life
+in the rocks which lie on top of the archæan rock, and are known as
+the Cambriani and Silurian periods. There we have creatures akin to
+our corals and crabs and worms, and others that are the distant
+kindred of the cuttle-fishes and of our lamp-shells. There were no
+backboned animals, that is to say, no land mammals, reptiles, or
+fishes at this stage of the earth's history. It is not likely that
+there was any land life except of plants and those forms like the
+lowest ferns, and probably mosses. Nor is it likely that there were
+any large continents as at the present time, but rather a host of
+islands lying where the great lands now are, the budding tops of the
+continents just appearing above the sea.
+
+Although the life of this time was far simpler than at the present
+day, it had about as great variety as we would find on our present
+sea-floors. There were as many different species living at the same
+time on a given surface.
+
+The Cambrian and Silurian time--the time before the coming of the
+fishes--must have endured for many million years without any great
+change in the world. Hosts of species lived and died; half a dozen
+times or more the life of the earth was greatly changed. New species
+came much like those that had gone before, and only a little gain here
+and there was perceptible at any time. Still, at the end of the
+Silurian, the life of the world had climbed some steps higher in
+structure and in intelligence.
+
+[Illustration: FIG. 1. NORTH AMERICA IN CAMBRIAN TIME.]
+
+The next set of periods is known as the Devonian. It is marked by the
+rapid extension of the fishes; for, although the fishes began in the
+uppermost Silurian, they first became abundant in this time. These,
+the first strong-jawed tyrants of the sea, came all at once, like a
+rush of the old Norman pirates into the peaceful seas of Great
+Britain. They made a lively time among the sluggish beings of that
+olden sea. Creatures that were able to meet feebler enemies were swept
+away or compelled to undergo great changes, and all the life of the
+oceans seems to have a spur given to it by these quicker-formed and
+quicker-willed animals. In this Devonian section of our rocks we have
+proofs that the lands were extensively covered with forests of low
+fern trees, and we find the first trace of air-breathing animals in
+certain insects akin to our dragon-flies. In this stage of the earth's
+history the fishes grew constantly more plentiful, and the seas had a
+great abundance of corals and crinoids. Except for the fishes, there
+were no very great changes in the character of the life from that
+which existed in the earlier time of the Cambrian and Silurian. The
+animals are constantly changing, but the general nature of the life
+remains the same as in the earlier time.
+
+[Illustration: FIG. 2. RANICEPS LYELLI--COAL TIME SALAMANDER.]
+
+In the Carboniferous or coal-bearing age, we have the second great
+change in the character of the life on the earth. Of the earlier
+times, we have preserved only the rocks formed in the seas. But rarely
+do we find any trace of the land life or even of the life that lived
+along the shores. In this Carboniferous time, however, we have very
+extensive sheets of rocks which were formed in swamps in the way shown
+in the earlier part of this book. They constitute our coal-beds,
+which, though much worn away by rain and sea, still cover a large part
+of the land surface. These beds of coal grew in the air, and, although
+the swamps where they were formed had very little animal life in them,
+we find some fossils which tell us that the life of the land was
+making great progress; there are new insects, including beetles,
+cockroaches, spiders, and scorpions, and, what is far more important,
+there are some air-breathing, back-boned animals, akin to the
+salamanders and water-dogs of the present day. These were nearly as
+large as alligators, and of much the same shape, but they were
+probably born from the egg in the shape of tadpoles and lived for a
+time in the water as our young frogs, toads, and salamanders do. This
+is the first step upwards from the fishes to land vertebrates; and we
+may well be interested in it, for it makes one most important advance
+in creatures through whose lives our own existence became possible.
+Still, these ancient woods of the coal period must have had little of
+the life we now associate with the forests; there were still no birds,
+no serpents, no true lizards, no suck-giving animals, no flowers, and
+no fruits. These coal-period forests were sombre wastes of shade, with
+no sound save those of the wind, the thunder, and the volcano, or of
+the running streams and the waves on the shores.
+
+In the seas of the Carboniferous time, we notice that the ancient life
+of the earth is passing away. Many creatures, such as the trilobites,
+die out, and many other forms such as the crinoids or sea lilies
+become fewer in kind and of less importance. These marks of decay in
+the marine life continue into the beds just after the Carboniferous,
+known as the Permian, which are really the last stages of the
+coal-bearing period.
+
+When with the changing time we pass to the beds known as the Triassic,
+which were made just after the close of the Carboniferous time, we
+find the earth undergoing swift changes in its life. The moist climate
+and low lands that caused the swamps to grow so rapidly have ceased to
+be, and in their place we appear to have warm, dry air, and higher
+lands.
+
+On these lands of the Triassic time the air-breathing life made very
+rapid advances. The plants are seen to undergo considerable changes.
+The ferns no longer make up all the forests, but trees more like the
+pines began to abound, and insects became more plentiful and more
+varied.
+
+[Illustration: FIG. 3. CYCAS CIRCINALIS, AKIN TO HIGHEST PLANTS OF
+COAL TIME.]
+
+Hitherto the only land back-boned animal was akin to our salamanders.
+Now we have true lizards in abundance, many of them of large size.
+Some of them were probably plant-eaters, but most were flesh-eaters;
+some seem to have been tenants of the early swamps, and some dwelt in
+the forests.
+
+The creatures related to the salamanders have increased in the variety
+of their forms to a wonderful extent. We know them best by the tracks
+which they have left on the mud stones formed on the borders of lakes
+or the edge of the sea. In some places these footprints are found in
+amazing numbers and perfection. The best place for them is in the
+Connecticut Valley, near Turner's Falls, Mass. At this point the red
+sandstone and shale beds, which are composed of thin layers having a
+total thickness of several hundred feet, are often stamped over by
+these footprints like the mud of a barnyard. From the little we can
+determine from these footprints, the creatures seem to have been
+somewhat related to our frogs, but they generally had tails, and,
+though provided with four legs, were in the habit of walking on the
+hind ones alone like the kangaroo. A few of these tracks are shown in
+the figure on this page.
+
+[Illustration: FIG. 4. FOOT-PRINTS, CONNECTICUT SANDSTONES.]
+
+These strange creatures were of many different species. Some of them
+must have been six or seven feet high, for their steps are as much as
+three feet apart, and seem to imply a creature weighing several
+hundred pounds. Others were not bigger than robins. Strangely enough,
+we have never found their bones nor the creatures on which they fed,
+and but for the formation of a little patch of rocks here and there we
+should not have had even these footprints to prove to us that such
+creatures had lived in the Connecticut Valley in this far-off time.
+
+[Illustration: FIG. 5. FOOT-PRINT, TURNER'S FALLS.]
+
+But these wonderful forms are less interesting than two or three
+little fossil jaw-bones that prove to us that in this Triassic time
+the earth now bore another animal more akin to ourselves, in the shape
+of a little creature that gave suck to its young. Once more life takes
+a long upward step in this little opossum-like animal, perhaps the
+first creature whose young was born alive. These little creatures
+called Microlestes or Dromatherium, of which only one or two different
+but related species have been found in England and in North Carolina,
+appear to have been insect-eaters of about the size and shape of the
+Australian creature shown in Fig. 7. So far we know it in but few
+specimens,--altogether only an ounce or two of bones,--but they are
+very precious monuments of the past.
+
+[Illustration: FIG. 6. DROMATHERIUM SYLVESTRE AND TEETH OF MICROLESTES
+ANTIQUUS.]
+
+In this Triassic time the climate appears to have been rather dry, for
+in it we have many extensive deposits of salt formed by the
+evaporation of closed lakes, of seas, such as are now forming on the
+bottom of the Dead Sea, and the Great Salt Lake of Utah, and a hundred
+or more other similar basins of the present day.
+
+[Illustration: FIG. 7. MYRMECOBIUS.]
+
+In the sea animals of this time we find many changes. Already some of
+the giant lizard-like animals, which first took shape on the land, are
+becoming swimming-animals. They changed their feet to paddles, which,
+with the help of a flattened tail, force them through the water.
+
+The fishes on which these great swimming lizards preyed are more like
+the fishes of our present day than they were before. The trilobites
+are gone, and of the crinoids only a remnant is left. Most of the
+corals of the earlier days have disappeared, but the mollusks have not
+changed more than they did at several different times in the earliest
+stages of the earth's history.
+
+[Illustration: FIG. 8. ICHTHYOSAURUS AND PLESIOSAURUS.]
+
+After the Trias comes a long succession of ages in which the life of
+the world is steadily advancing to higher and higher planes; but for a
+long time there is no such startling change as that which came in the
+passage from the coal series of rocks to the Trias. This long set of
+periods is known to geologists as the age of reptiles. It is well
+named, for the kindred of the lizards then had the control of the
+land. There were then none of our large fish to dispute their control,
+so they shaped themselves to suit all the occupations that could give
+them a chance for a living. Some remained beasts of prey like our
+alligators, but grew to larger size; some took to eating the plants,
+and came to walk on their four legs as our ordinary beasts do, no
+longer dragging themselves on their bellies as do the lizard and
+alligator, their lower kindred. Others became flying creatures like
+our bats, only vastly larger, often with a spread of wing of fifteen
+or twenty feet. Yet others, even as strangely shaped, dwelt with the
+sharks in the sea.
+
+[Illustration: FIG. 9. REPTILES OF JURASSIC PERIOD.]
+
+In this time of the earth's history we have the first bird-like forms.
+They were feathered creatures, with bills carrying true teeth, and
+with strong wings; but they were reptiles in many features, having
+long, pointed tails such as none of our existing birds have. They show
+us that the birds are the descendants of reptiles, coming off from
+them as a branch does from the parent tree. The tortoises began in
+this series of rocks. At first they are marine or swimming forms, the
+box-turtles coming later. Here too begin many of the higher insects.
+Creatures like moths and bees appear, and the forests are enlivened
+with all the important kinds of insects, though the species were very
+different from those now living.
+
+In the age of reptiles the plants have made a considerable advance.
+Palms are plenty; forms akin to our pines and firs abound, and the old
+flowerless group of ferns begins to shrink in size, and no longer
+spreads its feathery foliage over all the land as before. Still there
+were none of our common broad-leaved trees; the world had not yet
+known the oaks, birches, maples, or any of our hard-wood trees that
+lose their leaves in autumn; nor were the flowering plants, those with
+gay blossoms, yet on the earth. The woods and fields were doubtless
+fresh and green, but they wanted the grace of blossoms, plants, and
+singing-birds. None of the animals could have had the social qualities
+or the finer instincts that are so common among animals of the present
+day. There were probably no social animals like our ants and bees, no
+merry singing creatures; probably no forms that went in herds. Life
+was a dull round of uncared-for birth, cruel self-seeking, and of
+death. The animals at best were clumsy, poorly-endowed creatures, with
+hardly more intelligence than our alligators.
+
+The little thread of higher life begun in the Microlestes and
+Dromatherium, the little insect-eating mammals of the forest, is
+visible all through this time. It held in its warm blood the powers of
+the time to come, but it was an insignificant thing among the mighty
+cold-blooded reptiles of these ancient lands. There are several
+species of them, but they are all small, and have no chance to make
+headway against the older masters of the earth.
+
+The Jurassic or first part of the reptilian time shades insensibly
+into the second part, called the Cretaceous, which immediately follows
+it. During this period the lands were undergoing perpetual changes;
+rather deep seas came to cover much of the land surfaces, and there is
+some reason to believe that the climate of the earth became much
+colder than it had been, at least in those regions where the great
+reptiles had flourished. It may be that it is due to a colder climate
+that we owe the rapid passing away of this gigantic reptilian life of
+the previous age. The reptiles, being cold-blooded, cannot stand even
+a moderate winter cold, save when they are so small that they can
+crawl deep into crevices in the rocks to sleep the winter away,
+guarded from the cold by the warmth of the earth. At any rate these
+gigantic animals rapidly ceased to be, so that by the middle of the
+Cretaceous period they were almost all gone, except those that
+inhabited the sea; and at the end of this time they had shrunk to
+lizards in size. The birds continue to increase and to become more
+like those of our day; their tails shrink away, their long bills lose
+their teeth; they are mostly water-birds of large size, and there are
+none of our songsters yet; still they are for the first time perfect
+birds, and no longer half-lizard in their nature.
+
+The greatest change in the plants is found in the coming of the
+broad-leaved trees belonging to the families of our oaks, maples, etc.
+Now for the first time our woods take on their aspect of to-day; pines
+and other cone-bearers mingle with the more varied foliage of
+nut-bearing or large-seeded trees. Curiously enough, we lose sight of
+the little mammals of the earlier time. This is probably because there
+is very little in the way of land animals of this period preserved to
+us. There are hardly any mines or quarries in the beds of this age to
+bring these fossils to light. In the most of the other rocks there is
+more to tempt man to explore them for coal ores or building stones.
+
+In passing from the Cretaceous to the Tertiary, we enter upon the
+threshold of our modern world. We leave behind all the great wonders
+of the old world, the gigantic reptiles, the forests of tree ferns,
+the seas full of ammonites and belemnites, and come among the no less
+wonderful but more familiar modern forms. We come at once into lands
+and seas where the back-boned animals are the ruling beings. The
+reptiles have shrunk to a few low forms,--the small lizards, the
+crocodiles and alligators, the tortoises and turtles, and, as if to
+mark more clearly the banishment of this group from their old empire,
+the serpents, which are peculiarly degraded forms of reptiles which
+have lost the legs they once had, came to be the commonest reptiles of
+the earth.
+
+The first mammals that have no pouches now appear. In earlier times,
+the suck-giving animals all belonged to the group that contains our
+opossums, kangaroos, etc. These creatures are much lower and feebler
+than the mammals that have no pouches. Although they have probably
+been on the earth two or three times as long as the higher mammals,
+they have never attained any eminent success whatever; they cannot
+endure cold climates; none of them are fitted for swimming as are the
+seals and whales, or for flying as the bats, or for burrowing as the
+moles; they are dull, weak things, which are not able to contend with
+their stronger, better-organized, higher kindred. They seem not only
+weak, but unable to fit themselves to many different kinds of
+existence.
+
+In the lower part of the Tertiary rocks, we find at once a great
+variety of large beasts that gave suck to their young. It is likely
+that these creatures had come into existence in a somewhat earlier
+time in other lands, where we have not been able to study the fossils;
+for to make their wonderful forms slowly, as we believe them to have
+been made, would require a very long time. It is probable that during
+the Cretaceous time, in some land where we have not yet had a chance
+to study the rocks, these creatures grew to their varied forms, and
+that in the beginning of the Tertiary time, they spread into the
+regions where we find their bones.
+
+Beginning with the Tertiary time, we find these lower kinsmen of man,
+through whom man came to be. The mammals were marked by much greater
+simplicity and likeness to each other than they now have. There were
+probably no monkeys, no horses, no bulls, no sheep, no goats, no
+seals, no whales, and no bats. All these animals had many-fingered
+feet. There were no cloven feet like those of our bulls, and no solid
+feet as our horses have. Their brains, which by their size give us a
+general idea of the intelligence of the creature, are small; hence we
+conclude that these early mammals were less intelligent than those of
+our day.
+
+It would require volumes to trace the history of the growth of these
+early mammals, and show how they, step by step, came to their present
+higher state. We will take only one of the simplest of these changes,
+which happens to be also the one which we know best. This is the
+change that led to the making of our common horses, which seem to have
+been brought into life on the continent of North America. The most
+singular thing about our horses is that the feet have but one large
+toe or finger, the hoof, the hard covering of which is the nail of
+that extremity. Now it seems hard to turn the weak, five-fingered
+feet of the animals of the lower Tertiary--feet which seem to be
+better fitted for tree-climbing than anything else--into feet such as
+we find in the horse. Yet the change is brought about by easy stages
+that lead the successive creatures from the weak and loose-jointed
+foot of the ancient forms to the solid, single-fingered horse's hoof,
+which is wonderfully well-fitted for carrying a large beast at a swift
+speed, and is so strong a weapon of defence that an active donkey can
+kill a lion with a well-delivered kick.
+
+[Illustration: FIG. 10. FEET OF TERTIARY MAMMALS.]
+
+The oldest of these creatures that lead to the horses is called
+_Eohippus_ or beginning horse. This fellow had on the forefeet four
+large toes, each with a small hoof and fifth imperfect one, which
+answered to the thumb. The hind feet had gone further in the change,
+for they each had but three toes, each with hoofs, the middle-toed
+hoof larger and longer than the others. A little later toward our day
+we find another advance in the _Orohippus_, when the little imperfect
+thumb has disappeared, and there are only four toes on the forefeet
+and three on the hind.
+
+Yet later we have the _Mesohippus_ or half-way horse. There are still
+three toes on the hind foot, but one more of the fingers of the
+forefeet has disappeared. This time it is the little finger that goes,
+leaving only a small bone to show that its going was by a slow
+shrinking. The creature now has three little hoofs on each of its
+feet.
+
+Still nearer our own time comes the _Miohippus_, which shows the two
+side hoofs on each foot shrinking up so that they do not touch the
+ground, but they still bear little hoofs. Lastly, about the time of
+man's coming on the earth, appears his faithful servant, the horse, in
+which those little side hoofs have disappeared, leaving only two
+little "splint" bones to mark the place where these side hoofs belong.
+Thus, step by step, our horses' feet were built up; while these parts
+were changing, the other parts of the animals were also slowly
+altering. They were at first smaller than our horses,--some of them
+not as large as an ordinary Newfoundland dog; others as small as
+foxes.
+
+[Illustration: FIG. 11. DEVELOPMENT OF HORSES'S FOOT.]
+
+As if to remind us of his old shape, our horses now and then, but
+rarely, have, in place of the little splint bones above the hoof, two
+smaller hoofs, just like the foot of _Miohippus_. Sometimes these are
+about the size of a silver dollar, on the part that receives the shoe
+when horses are shod.
+
+In this way, by slow-made changes, the early mammals pass into the
+higher. Out of one original part are made limbs as different as the
+feet of the horse, the wing of a bat, the paddle of a whale, and the
+hand of man. So with all the parts of the body the forms change to
+meet the different uses to which they are put.
+
+At the end of this long promise, which was written in the very first
+animals, comes man himself, in form closely akin to the lower animals,
+but in mind immeasurably apart from them. We can find every part of
+man's body in a little different shape in the monkeys, but his mind is
+of a very different quality. While his lower kindred cannot be made to
+advance in intelligence any more than man himself can grow a horse's
+foot or a bat's wing, he is constantly going higher and higher in his
+mental and moral growth.
+
+So far we have found but few traces of man that lead us to suppose
+that he has been for a long geological time on the earth, yet there is
+good evidence that he has been here for a hundred thousand years or
+more. It seems pretty clear that he has changed little in his body in
+all these thousands of generations. The earliest remains show us a
+large-brained creature, who used tools and probably had already made a
+servant of fire, which so admirably aids him in his work.
+
+Besides the development of this wonderful series of animals, that we
+may call in a certain way our kindred, there have been several other
+remarkable advances in this Tertiary time, this age of crowning
+wonders in the earth's history. The birds have gone forward very
+rapidly; it is likely that there were no songsters at the first part
+of this period, but these singing birds have developed very rapidly in
+later times. Among the insects the most remarkable growth is among the
+ants, the bees, and their kindred. These creatures have very wonderful
+habits; they combine together for the making of what we may call
+states, they care for their young, they wage great battles, they keep
+slaves, they domesticate other insects, and in many ways their acts
+resemble the doings of man. Coming at about the same time as man,
+these intellectual insects help to mark this later stage of the earth
+as the intellectual period in its history. Now for the first time
+creatures are on the earth which can form societies and help each
+other in the difficult work of living.
+
+Among the mollusks, the most important change is in the creation of
+the great, strong swimming squids, the most remarkable creatures of
+the sea. Some of these have arms that can stretch for fifty feet from
+tip to tip.
+
+Among the plants, the most important change has been in the growth of
+flowering plants, which have been constantly becoming more plenty, and
+the plants which bear fruits have also become more numerous. The
+broad-leaved trees seem to be constantly gaining on the forests of
+narrow-leaved cone-bearers, which had in an earlier day replaced the
+forests of ferns.
+
+In these Tertiary ages, as in the preceding times of the earth, the
+lands and seas were much changed in their shape. It seems that in the
+earlier ages the land had been mostly in the shape of large islands
+grouped close together where the continents now are. In this time,
+these islands grew together to form the united lands of Europe, Asia,
+Africa, Australia, and the twin American continents; so that, as life
+rose higher, the earth was better fitted for it. Still there were
+great troubles that it had to undergo. There were at least two
+different times during the Tertiary age termed glacial periods, times
+when the ice covered a large part of the northern continents,
+compelling life of all sorts to abandon great regions, and to find new
+places in more southern lands. Many kinds of animals and plants seem
+to have been destroyed in these journeys; but these times of trial, by
+removing the weaker and less competent creatures, made room for new
+forms to rise in their places. All advance in nature makes death
+necessary, and this must come to races as well as to individuals if
+the life of the world is to go onward and upward.
+
+Looking back into the darkened past, of which we yet know but little
+compared with what we would like to know, we can see the great armies
+of living beings led onward from victory to victory toward the higher
+life of our own time. Each age sees some advance, though death
+overtakes all its creatures. Those that escape their actual enemies or
+accident, fall a prey to old age: volcanoes, earthquakes, glacial
+periods, and a host of other violent accidents sweep away the life of
+wide regions, yet the host moves on under a control that lies beyond
+the knowledge of science. Man finds himself here as the crowning
+victory of this long war. For him all this life appears to have
+striven. In his hands lies the profit of all its toil and pain.
+Surely this should make us feel that our duty to all these living
+things, that have shared in the struggle that has given man his
+elevation, is great, but above all, great is our duty to the powers
+that have been placed in our bodies and our minds.
+
+[Illustration: A GLACIER.]
+
+
+
+
+THE PITCH LAKE IN THE WEST INDIES
+
+(FROM AT LAST.)
+
+BY C. KINGSLEY.
+
+
+[Illustration: COOLIE AND NEGRO.]
+
+The Pitch Lake, like most other things, owes its appearance on the
+surface to no convulsion or vagary at all, but to a most slow,
+orderly, and respectable process of nature, by which buried vegetable
+matter, which would have become peat, and finally brown coal, in a
+temperate climate, becomes, under the hot tropic soil, asphalt and
+oil, continually oozing up beneath the pressure of the strata above
+it....
+
+       *       *       *       *       *
+
+As we neared the shore, we perceived that the beach was black with
+pitch; and the breeze being off the land, the asphalt smell (not
+unpleasant) came off to welcome us. We rowed in, and saw in front of a
+little row of wooden houses a tall mulatto, in blue policeman's dress,
+gesticulating and shouting to us. He was the ward policeman, and I
+found him (as I did all the colored police) able and courteous, shrewd
+and trusty. These police are excellent specimens of what can be made
+of the negro, or half-negro, if he be but first drilled, and then
+given a responsibility which calls out his self-respect. He was
+warning our crew not to run aground on one or other of the pitch
+reefs, which here take the place of rocks. A large one, a hundred
+yards off on the left, has been almost all dug away, and carried to
+New York or to Paris to make asphalt-pavement.
+
+[Illustration: THE POLICE STATION.]
+
+The boat was run ashore, under his directions, on a spit of sand
+between the pitch; and when she ceased bumping up and down in the
+muddy surf, we scrambled out into a world exactly the hue of its
+inhabitants of every shade, from jet black to copper-brown. The
+pebbles on the shore were pitch. A tide-pool close by was enclosed in
+pitch; a four-eyes was swimming about in it, staring up at us; and
+when we hunted him, tried to escape, not by diving, but by jumping on
+shore on the pitch, and scrambling off between our legs. While the
+policeman, after profoundest courtesies, was gone to get a mule-cart
+to take us up to the lake, and planks to bridge its water channels,
+we took a look round at this oddest of corners of the earth.
+
+In front of us was the unit of civilization,--the police-station,
+wooden, on wooden stilts (as all well-built houses are here), to
+insure a draught of air beneath them. We were, of course, asked to
+come in and sit down, but preferred looking about, under our
+umbrellas; for the heat was intense. The soil is half pitch, half
+brown earth, among which the pitch sweals in and out as tallow sweals
+from a candle. It is always in slow motion under the heat of the
+tropic sun; and no wonder if some of the cottages have sunk right and
+left in such a treacherous foundation. A stone or brick house could
+not stand here; but wood and palm-thatch are both light and tough
+enough to be safe, let the ground give way as it will.
+
+The soil, however, is very rich. The pitch certainly does not injure
+vegetation, though plants will not grow actually in it. The first
+plants which caught our eyes were pine-apples, for which La Brea is
+famous. The heat of the soil, as well as the air, brings them to
+special perfection. They grow about anywhere, unprotected by hedge or
+fence; for the negroes here seem honest enough, at least toward each
+other; and at the corner of the house was a bush worth looking at, for
+we had heard of it for many a year. It bore prickly, heart-shaped pods
+an inch long, filled with seeds coated with a red waxy pulp.
+
+This was a famous plant--_Bixa orellana Roucou_; and that pulp was the
+well-known annotto dye of commerce. In England and Holland it is used
+merely, I believe, to color cheeses, but in the Spanish Main to color
+human beings. The Indian of the Orinoco prefers paint to clothes; and
+when he has "roucoued" himself from head to foot, considers himself in
+full dress, whether for war or dancing. Doubtless he knows his own
+business best from long experience. Indeed, as we stood broiling on
+the shore, we began somewhat to regret that European manners and
+customs prevented our adopting the Guaraon and Arrawak fashion.
+
+[Illustration: THE MULE-CART.]
+
+The mule-cart arrived; the lady of the party was put into it on a
+chair, and slowly bumped and rattled past the corner of Dundonald
+Street--so named after the old sea-hero, who was, in his life-time,
+full of projects for utilizing this same pitch--and up in pitch road,
+with a pitch gutter on each side.
+
+The pitch in the road has been, most of it, laid down by hand, and is
+slowly working down the slight incline, leaving pools and ruts full of
+water, often invisible, because covered with a film of brown
+pitch-dust, and so letting in the unwary walker over his shoes. The
+pitch in the gutter-bank is in its native place, and as it spues
+slowly out of the soil into the ditch in odd wreaths and lumps, we
+could watch, in little, the process which has produced the whole
+deposit--probably the whole lake itself.
+
+A bullock-cart, laden with pitch, came jolting down past us, and we
+observed that the lumps, when the fracture is fresh, have all a drawn
+out look; that the very air bubbles in them, which are often very
+numerous, are all drawn out likewise, long and oval, like the
+air-bubbles in some ductile lavas.
+
+On our left, as we went on, the bush was low, all of yellow cassia and
+white Hibiscus, and tangled with lovely convolvulus-like creepers,
+Ipomoea and Echites, with white, purple or yellow flowers. On the
+right were negro huts and gardens, fewer and fewer as we went on,--all
+rich with fruit trees, especially with oranges, hung with fruit of
+every hue; and beneath them, of course, the pine-apples of La Brea.
+Everywhere along the road grew, seemingly wild here, that pretty low
+tree, Cashew, with rounded yellow-veined leaves and little green
+flowers, followed by a quaint pink and red-striped pear, from which
+hangs, at the larger and lower end, a kidney-shaped bean, which bold
+folk eat when roasted; but woe to those who try it when raw; for the
+acrid oil blisters the lips, and even while the beans are roasting the
+fumes of the oil will blister the cook's face if she holds it too near
+the fire.
+
+As we went onward up the gentle slope (the rise is one hundred and
+thirty-eight feet in rather more than a mile), the ground became more
+and more full of pitch, and the vegetation poorer and more rushy,
+till it resembled, on the whole, that of an English fen. An Ipomoea or
+two, and a scarlet flowered dwarf Heliconia, kept up the tropic type,
+as does a stiff brittle fern about two feet high. We picked the weeds,
+which looked like English mint or basil, and found that most of them
+had three longitudinal nerves in each leaf, and were really
+Melastomas, though dwarfed into a far meaner habit than that of the
+noble forms we saw at Chaguanas, and again on the other side of the
+lake. On the right, too, in a hollow, was a whole wood of Groogroo
+palms, gray stemmed, gray leaved, and here and there a patch of white
+or black Roseau rose gracefully eight or ten feet high among the
+reeds.
+
+The plateau of pitch now widened out, and the whole ground looked like
+an asphalt pavement, half overgrown with marsh-loving weeds, whose
+roots feed in the sloppy water which overlies the pitch. But, as yet,
+there was no sign of the lake. The incline, though gentle, shuts off
+the view of what is beyond. This last lip of the lake has surely
+overflowed, and is overflowing still, though very slowly. Its furrows
+all curve downward; and it is, in fact, as one of our party said, "a
+black glacier." The pitch, expanding under the burning sun of day,
+must needs expand most toward the line of least resistance--that is,
+downhill; and when it contracts again under the coolness of night, it
+contracts, surely, from the same cause, more downhill than uphill; and
+so each particle never returns to the spot whence it started, but
+rather drags the particles above it downward toward itself. At least,
+so it seemed to us. Thus may be explained the common mistake which is
+noticed by Messrs. Wall and Sawkins in their admirable description of
+the lake.
+
+"All previous descriptions refer the bituminous matter scattered over
+the La Brea district, and especially that between the village and the
+lake, to streams which have issued at some former epoch from the lake,
+and extended into the sea. This supposition is totally incorrect, as
+solidification would probably have ensued before it had proceeded
+one-tenth of the distance; and such of the asphalt as has undoubtedly
+escaped from the lake has not advanced more than a few yards, and
+always presents the curved surfaces already described, and never
+appears as an extended sheet."
+
+Agreeing with this statement as a whole, I nevertheless cannot but
+think it probable that a great deal of the asphalt, whether it be in
+large masses or in scattered veins, may be moving very slowly down
+hill, from the lake to the sea, by the process of expansion by day and
+contraction by night, and may be likened to a caterpillar, or rather
+caterpillars innumerable, progressing by expanding and contracting
+their rings, having strength enough to crawl down hill, but not
+strength enough to back up hill again.
+
+At last we surmounted the last rise, and before us lay the famous
+lake--not at the bottom of a depression, as we expected, but at the
+top of a rise, whence the ground slopes away from it on two sides, and
+rises from it very slightly on the two others. The black pool glared
+and glittered in the sun. A group of islands, some twenty yards wide,
+were scattered about the middle of it. Beyond it rose a double forest
+of Moriche fan-palms; and to the right of them high wood with giant
+Mombins and undergrowth of Cocorite--a paradise on the other side of
+the Stygian pool.
+
+[Illustration: THE PITCH LAKE.]
+
+We walked, with some misgivings, on to the asphalt, and found it
+perfectly hard. In a few steps we were stopped by a channel of clear
+water, with tiny fish and water-beetles in it; and, looking round, saw
+that the whole lake was intersected with channels, so unlike anything
+which can be seen elsewhere that it is not easy to describe them.
+
+Conceive a crowd of mushrooms, of all shapes, from ten to fifty feet
+across, close together side by side, their tops being kept at exactly
+the same level, their rounded rims squeezed tight against each other;
+then conceive water poured on them so as to fill the parting seams,
+and in the wet season, during which we visited it, to overflow the
+tops somewhat. Thus would each mushroom represent, tolerably well, one
+of the innumerable flat asphalt bosses, which seem to have sprung up
+each from a separate centre, while the parting seams would be of much
+the same shape as those in the asphalt, broad and shallow atop, and
+rolling downward in a smooth curve, till they are at bottom mere
+cracks from two to ten feet deep. Whether these cracks actually close
+up below, and the two contiguous masses of pitch become one, cannot be
+seen. As far as the eye goes down, they are two, though pressed close
+to each other. Messrs. Wall and Sawkins explain the odd fact clearly
+and simply. The oil, they say, which the asphalt contains when it
+rises first, evaporates in the sun, of course most on the outside of
+the heap, leaving a thorough coat of asphalt, which has, generally, no
+power to unite with the corresponding coat of the next mass. Meanwhile
+Mr. Manross, an American gentleman, who has written a very clever and
+interesting account of the lake, seems to have been so far deceived by
+the curved and squeezed edges of these masses that he attributes to
+each of them a revolving motion, and supposes that the material is
+continually passing from the centre to the edges, when it "rolls
+under," and rises again in the middle. Certainly the strange stuff
+looks, at the first glance, as if it were behaving in this way; and
+certainly, also, his theory would explain the appearance of sticks and
+logs in the pitch. But Messrs. Wall and Sawkins say that they have
+observed no such motion: nor did we; and I agree with them, that it is
+not very obvious to what force, or what influence, it could be
+attributable. We must, therefore, seek some other way of accounting
+for the sticks--which utterly puzzled us, and which Mr. Manross well
+describes as "numerous pieces of wood, which, being involved in the
+pitch, are constantly coming to the surface. They are often several
+feet in length, and five or six inches in diameter. On reaching the
+surface they generally assume an upright position, one end being
+detained in the pitch, while the other is elevated by the lifting of
+the middle. They may be seen at frequent intervals over the lake,
+standing up to the height of two or even three feet. They look like
+stumps of trees protruding through the pitch; but their parvenu
+character is curiously betrayed by a ragged cap of pitch which
+invariably covers the top, and hangs down like hounds' ears on either
+side."
+
+Whence do they come? Have they been blown on to the lake, or left
+behind by man? or are they fossil trees, integral parts of the
+vegetable stratum below which is continually rolling upward? or are
+they of both kinds? I do not know. Only this is certain, as Messrs.
+Wall and Sawkins have pointed out, that not only "the purer varieties
+of asphalt, such as approach or are identical with asphalt glance,
+have been observed" (though not, I think, in the lake itself) "in
+isolated masses, where there was little doubt of their proceeding from
+ligneous substances of larger dimensions, such as roots and pieces of
+trunks and branches," but, moreover, that "it is also necessary to
+admit a species of conversion by contact, since pieces of wood
+included accidentally in the asphalt, for example, by dropping from
+overhanging vegetation, are often found partially transformed into the
+material." This is a statement which we verified again and again, as
+we did the one which follows, namely, that the hollow bubbles which
+abound on the surface of the pitch "generally contain traces of the
+lighter portion of vegetation," and "are manifestly derived from
+leaves, etc., which are blown about the lake by the wind, and are
+covered with asphalt, and, as they become asphalt themselves, give off
+gases which form bubbles round them."
+
+But how is it that those logs stand up out of the asphalt, with
+asphalt caps and hounds' ears (as Mr. Manross well phrases it) on the
+tops of them?
+
+We pushed on across the lake, over the planks which the negroes laid
+down from island to island. Some, meanwhile, preferred a steeple-chase
+with water-jumps, after the fashion of the midshipmen on a certain
+second visit to the lake. How the negroes grinned delight and surprise
+at the vagaries of English lads--a species of animal altogether new to
+them; and how they grinned still more when certain staid and portly
+dignitaries caught the infection, and proved by more than one good
+leap that they too had been English school-boys--alas! long, long ago.
+
+So, whether by bridging, leaping, or wading, we arrived at the little
+islands, and found them covered with a thick, low scrub; deep sedge,
+and among them Pinguins, like huge pine-apples without the apple; gray
+wild-pines, parasites on Matapalos, which, of course, have established
+themselves, like robbers and vagrants as they are, everywhere; a true
+holly, with box-like leaves; and a rare cocoa-plum, very like the
+holly in habit, which seems to be all but confined to these little
+patches of red earth, afloat on the pitch. Out of the scrub, when we
+were there, flew off two or three night-jars, very like our English
+species, save that they had white in the wings; and on the second
+visit one of the midshipmen, true to the English boy's bird's-nesting
+instinct, found one of their eggs, white-spotted, in a grass nest.
+
+Passing these little islands, which are said (I know not how truly) to
+change their places and number, we came to the very fountains of Styx,
+to that part of the lake where the asphalt is still oozing up.
+
+As the wind set toward us, we soon became aware of an evil
+smell--petroleum and sulphureted hydrogen at once--which gave some of
+us a headache. The pitch here is yellow and white with sulphur foam;
+so are the water-channels; and out of both water and pitch innumerable
+bubbles of gas arise, loathsome to the smell. We became aware that the
+pitch was soft under our feet. We left the impression of our boots;
+and if we had stood still awhile, we should soon have been ankle-deep.
+No doubt there are spots where, if a man stayed long enough, he would
+be slowly and horribly engulfed. "But," as Mr. Manross says truly, "in
+no place is it possible to form those bowl-like depressions round the
+observer described by former travellers." What we did see is that the
+fresh pitch oozes out at the lines of least resistance, namely, in the
+channels between the older and more hardened masses, usually at the
+upper ends of them, so that one may stand on pitch comparatively hard,
+and put one's hand into pitch quite liquid, which is flowing softly
+out, like some ugly fungoid growth, such as may be seen in old
+wine-cellars, into the water. One such pitch-fungus had grown several
+yards in length in the three weeks between our first and second visit;
+and on another, some of our party performed exactly the same feat as
+Mr. Manross.
+
+"In one of the star-shaped pools of water, some five feet deep, a
+column of pitch had been forced perpendicularly up from the bottom. On
+reaching the surface of the water it had formed a sort of
+centre-table, about four feet in diameter, but without touching the
+sides of the pool. The stem was about a foot in diameter. I leaped out
+on this table, and found that it not only sustained my weight, but
+that the elasticity of the stem enabled me to rock it from side to
+side. Pieces torn from the edges of this table sank readily, showing
+that it had been raised by pressure, and not by its buoyancy."
+
+True, though strange; but stranger still did it seem to us when we did
+at last what the negroes asked us, and dipped our hands into the
+liquid pitch, to find that it did not soil the fingers. The old
+proverb that one cannot touch pitch without being defiled happily does
+not stand true here, or the place would be intolerably loathsome. It
+can be scraped up, moulded into any shape you will, wound in a string
+(as was done by one of the midshipmen) round a stick, and carried off;
+but nothing is left on the hand save clean gray mud and water. It may
+be kneaded for an hour before the mud be sufficiently driven out of it
+to make it sticky. This very abundance of earthy matter it is which,
+while it keeps the pitch from soiling, makes it far less valuable than
+it would be were it pure.
+
+It is easy to understand whence this earthy matter (twenty or thirty
+per cent) comes. Throughout the neighborhood the ground is full, to
+the depth of hundreds of feet, of coaly and asphaltic matter. Layers
+of sandstone or of shale containing this decayed vegetable alternate
+with layers which contain none; and if, as seems probable, the coaly
+matter is continually changing into asphalt and oil, and then working
+its way upward through every crack and pore, to escape from the
+enormous pressure of the superincumbent soil, it must needs carry up
+with it innumerable particles of the soils through which it passes.
+
+In five minutes we had seen, handled, and smelt enough to satisfy us
+with this very odd and very nasty vagary of tropic nature; and as we
+did not wish to become faint and ill between the sulphureted hydrogen
+and the blaze of the sun reflected off the hot black pitch, we hurried
+on over the water-furrows, and through the sedge-beds to the farther
+shore--to find ourselves, in a single step, out of an Inferno into a
+Paradise.
+
+[Illustration]
+
+
+
+
+A STALAGMITE CAVE
+
+(FROM THE VOYAGE OF THE CHALLENGER.)
+
+BY SIR C. WYVILLE THOMSON, KT., LL.D., ETC.
+
+
+[Illustration]
+
+I think the Painter's Vale cave is the prettiest of the whole. The
+opening is not very large. It is an arch over a great mass of débris
+forming a steep slope into the cave, as if part of the roof of the
+vault had suddenly fallen in. At the foot of the bank of débris one
+can barely see in the dim light the deep clear water lying perfectly
+still and reflecting the roof and margin like a mirror. We clambered
+down the slope, and as the eye became more accustomed to the obscurity
+the lake stretched further back. There was a crazy little punt moored
+to the shore, and after lighting candles Captain Nares rowed the
+Governor back into the darkness, the candles throwing a dim light for
+a time--while the voices became more hollow and distant--upon the
+surface of the water and the vault of stalactite, and finally passing
+back as mere specks into the silence.
+
+[Illustration: A GUIDE.]
+
+After landing the Governor on the opposite side, Captain Nares
+returned for me, and we rowed round the weird little lake. It was
+certainly very curious and beautiful; evidently a huge cavity out of
+which the calcareous sand had been washed or dissolved, and whose
+walls, still to a certain extent permeable, had been hardened and
+petrified by the constant percolation of water charged with carbonate
+of lime. From the roof innumerable stalactites, perfectly white, often
+several yards long and coming down to the delicacy of knitting-needles,
+hung in clusters; and wherever there was any continuous crack in the
+roof or wall, a graceful, soft-looking curtain of white stalactite
+fell, and often ended, much to our surprise. Deep in the water
+Stalagmites also rose up in pinnacles and fringes through the water,
+which was so exquisitely still and clear that it was something
+difficult to tell where the solid marble tracery ended, and its
+reflected image began. In this cave, which is a considerable distance
+from the sea, there is a slight change of level with the tide
+sufficient to keep the water perfectly pure. The mouth of the cave is
+overgrown with foliage, and every tree is draped and festooned with
+the fragrant _Jasminum gracile_, mingled not unfrequently with the
+"poison ivy" (_Rhus toxicodendron_). The Bermudians, especially the
+dark people, have a most exaggerated horror of this bush. They imagine
+that if one touch it or rub against it he becomes feverish, and is
+covered with an eruption. This is no doubt entirely mythical. The
+plant is very poisonous, but the perfume of the flower is rather
+agreeable, and we constantly plucked and smelt it without its
+producing any unpleasant effect. The tide was with us when we regained
+the Flats Bridge, and the galley shot down the rapid like an arrow,
+the beds of scarlet sponges and the great lazy trepangs showing
+perfectly clearly on the bottom at a fathom depth.
+
+[Illustration: FIG. 1. CALCAREOUS CONCRETION SIMULATING A FOSSIL
+PALM-STEM, BOAZ ISLAND, BERMUDAS.]
+
+Every here and there throughout the islands there are groups of bodies
+of very peculiar form projecting from the surface of the limestone
+where it has been weathered. These have usually been regarded as
+fossil palmetto stumps, the roots of trees which have been overwhelmed
+with sand and whose organic matter has been entirely removed and
+replaced by carbonate of lime. Fig. 1 represents one of the most
+characteristic of these from a group on the side of the road in Boaz
+Island. It is a cylinder a foot in diameter and six inches or so high;
+the upper surface forms a shallow depression an inch deep surrounded
+by a raised border; the bottom of the cup is even, and pitted over
+with small depressions like the marks of rain-drops on sand; the walls
+of the cylinder seem to end a few inches below the surface of the
+limestone in a rounded boss, and all over this there are round
+markings or little cylindrical projections like the origins of
+rootlets. The object certainly appears to agree even in every detail
+with a fossil palm-root, and as the palmetto is abundant on the
+islands and is constantly liable to be destroyed by and ultimately
+enveloped in a mass of moving sand, it seemed almost unreasonable to
+question its being one. Still something about the look of these things
+made me doubt, with General Nelson, whether they were fossil palms, or
+indeed whether they were of organic origin at all; and after carefully
+examining and pondering over several groups of them, at Boaz Island,
+on the shore at Mount Langton, and elsewhere, I finally came to the
+conclusion that they were not fossils, but something totally
+different.
+
+[Illustration: FIG. 2. CALCAREOUS CONCRETION IN AEOLIAN LIMESTONE,
+BERMUDAS.]
+
+[Illustration: FIG. 3. CALCAREOUS CONCRETION IN AEOLIAN LIMESTONE,
+BERMUDAS.]
+
+[Illustration: FIG. 4. CALCAREOUS CONCRETION, BERMUDAS.]
+
+[Illustration: FIG. 5. CALCAREOUS CONCRETION IN AEOLIAN LIMESTONE,
+BERMUDAS.]
+
+The form given in Fig. 1 is the most characteristic, and probably by
+far the most common; but very frequently one of a group of these, one
+which is evidently essentially the same as the rest and formed in the
+same way, has an oval or an irregular shape (Figs. 2, 3, and 4). In
+these we have the same raised border, the same scars on the outside,
+the same origins of root-like fibres, and the same pitting of the
+bottom of the shallow cup; but their form precludes the possibility of
+their being tree-roots. In some cases (Fig. 5), a group of so-called
+"palm-stems" is inclosed in a space surrounded by a ridge, and on
+examining it closely this outer ridge is found to show the same
+leaf-scars and traces of rootlets as the "palm-stems" themselves. In
+some cases very irregular honey-combed figures are produced which the
+examination of a long series of intermediate forms shows to belong to
+the same category (Fig. 6).
+
+[Illustration: FIG. 6. CONCRETIONS IN AEOLIAN ROCKS, BERMUDAS.]
+
+In the caves in the limestone, owing to a thread of water having found
+its way in a particular direction through the porous stone of the
+roof, a drop falls age after age on one spot on the cave-floor,
+accurately directed by the stalactite which it is all the time
+creating. The water contains a certain proportion of carbonate of
+lime, which is deposited as stalagmite as the water evaporates, and
+thus a ring-like crust is produced at a little distance from the spot
+where the drop falls. When a ring is once formed, it limits the spread
+of the drop, and determines the position of the wall bounding the
+little pool made by the drop. The floor of the cave gradually rises by
+the accumulation of sand and travertine, and with it rise the walls
+and floor of the cup by the deposit of successive layers of stalagmite
+produced by the drop percolating into the limestone of the floor which
+hardens it still further, but in this peculiar symmetrical way. From
+the floor and sides of the cup the water oozes into the softer
+limestone around and beneath; but, as in all these limestones, it does
+not ooze indiscriminately, but follows certain more free paths. These
+become soon lined and finally blocked with stalagmite, and it is
+these tubes and threads of stalagmite which afterwards in the
+pseudo-fossil represent the diverging rootlets.
+
+[Illustration: A STALAGMITE CAVE.]
+
+Sometimes when two or more drops fall from stalactites close to one
+another the cups coalesce (Figs. 2, 3, and 4); sometimes one drop or
+two is more frequent than the other, and then we have the form shown
+in Figs. 3 and 4; sometimes many drops irregularly scattered form a
+large pool with its raised border, and a few drops more frequent and
+more constant than the rest grow their "palmetto stems" within its
+limit (Fig. 5); and sometimes a number of drops near one another make
+a curious regular pattern, with the partitions between the recesses
+quite straight (Fig. 6).
+
+I have already referred to the rapid denudation which is going on in
+these islands, and to the extent to which they have been denuded
+within comparatively recent times. The floors of caves, from their
+being cemented into a nearly homogeneous mass by stalagmitic matter,
+are much harder than the ordinary porous blown limestone; and it seems
+that in many cases, after the rocks forming the walls and roof have
+been removed, disintegration has been at all events temporarily
+arrested by the floor. Where there is a flat surface of rock exposed
+anywhere on the island, it very generally bears traces of having been
+at one time the floor of a cave; and as the weather-wearing of the
+surface goes on, the old concretionary structures are gradually
+brought out again, the parts specially hardened by a localized slow
+infiltration of lime resist integration longest and project above the
+general surface. Often a surface of weathered rock is so studded with
+these symmetrical concretions, that it is hard to believe that one is
+not looking at the calcified stumps of a close-growing grove of palms.
+
+[Illustration]
+
+
+
+
+THE BIG TREES OF CALIFORNIA
+
+(FROM STUDIES SCIENTIFIC AND SOCIAL.)
+
+BY ALFRED RUSSEL WALLACE.
+
+
+[Illustration]
+
+In the popular accounts of these trees it is usual to dwell only on
+the dimensions of the very largest known specimens, and sometimes even
+to exaggerate these. Even the smaller full-grown trees, however, are
+of grand dimensions, varying from fourteen to eighteen feet in
+diameter, at six feet above the ground, and keeping nearly the same
+thickness for perhaps a hundred feet. In the south Calaveras grove,
+where there are more than a thousand trees, the exquisite beauty of
+the trunks is well displayed by the numerous specimens in perfect
+health and vigor. The bark of these trees, seen at a little distance,
+is of a bright orange brown tint, delicately mottled with darker
+shades, and with a curious silky or plush-like gloss, which gives them
+a richness of color far beyond that of any other conifer. The tree
+which was cut down soon after the first discovery of the species, the
+stump of which is now covered with a pavilion, is twenty-five feet in
+diameter at six feet above the ground, but this is without the thick
+bark, which would bring it to twenty-seven feet when alive. A
+considerable portion of this tree still lies where it fell, and at one
+hundred and thirty feet from the base I found it to be still twelve
+and a half feet in diameter (or fourteen feet with the bark), while at
+the extremity of the last piece remaining, two hundred and fifteen
+feet from its base, it is six feet in diameter, or at least seven feet
+with the bark. The height of this tree when it was cut down is not
+recorded, but as one of the living trees is more than three hundred
+and sixty feet high, it is probable that this giant was not much short
+of four hundred feet.
+
+[Illustration: THE "MOTHER OF THE FOREST."]
+
+In the accompanying picture the dead tree in the centre is that from
+which the bark was stripped, which was erected in the Crystal Palace
+and unfortunately destroyed by fire. It is called the "Mother of the
+Forest." The two trees nearer the foreground are healthy, medium-sized
+trees, about fifteen feet diameter at six feet above the ground.
+
+The huge decayed trunk called "Father of the Forest," which has fallen
+perhaps a century or more, exhibits the grandest dimensions of any
+known tree. By measuring its remains, and allowing for the probable
+thickness of the bark, it seems to have been about thirty-five feet
+diameter near the ground, at ninety feet up fifteen feet, and even at
+a height of two hundred and seventy feet, it was nine feet in
+diameter. It is within the hollow trunk of this tree that a man on
+horse-back can ride--both man and horse being rather small; but the
+dimensions undoubtedly show that it was considerably larger than the
+"Pavilion tree," and that it carried its huge dimensions to a greater
+altitude; and although this does not prove it to have been much
+taller, yet it was in all probability more than four hundred feet in
+height.
+
+[Illustration]
+
+Very absurd statements are made to visitors as to the antiquity of
+these trees, three or four thousand years being usually given as their
+age. This is founded on the fact that while many of the large Sequoias
+are greatly damaged by fire, the large pines and firs around them are
+quite uninjured. As many of these pines are assumed to be near a
+thousand years old, the epoch of the "great fire" is supposed to be
+earlier still, and as the Sequoias have not outgrown the fire-scars in
+all that time, they are supposed to have then arrived at their full
+growth. But the simple explanation of these trees alone having
+suffered so much from fire is, that their bark is unusually thick,
+dry, soft, and fibrous, and it thus catches fire more easily and
+burns more readily and for a longer time than that of the other
+coniferæ. Forest fires occur continually, and the visible damage done
+to these trees has probably all occurred in the present century.
+Professor C.B. Bradley, of the University of California, has carefully
+counted the rings of annual growth on the stump of the "Pavilion
+tree," and found them to be twelve hundred and forty; and after
+considering all that has been alleged as to the uncertainty of this
+mode of estimating the age of a tree, he believes that in the climate
+of California, in the zone of altitude where these trees grow, the
+seasons of growth and repose are so strongly marked that the number of
+annual rings gives an accurate result.
+
+Other points that have been studied by Professor Bradley are, the
+reason why there are so few young trees in the groves, and what is the
+cause of the destruction of the old trees. To take the last point
+first, these noble trees seem to be singularly free from disease or
+from decay due to old age. All the trees that have been cut down are
+solid to the heart, and none of the standing trees show any
+indications of natural decay. The only apparent cause for their
+overthrow is the wind, and by noting the direction of a large number
+of fallen trees it is found that the great majority of them lie more
+or less towards the south. This is not the direction of the prevalent
+winds, but many of the tallest trees lean towards the south, owing to
+the increased growth of their topmost branches towards the sun. They
+are then acted upon by violent gales, which loosen their roots, and
+whatever the direction of the wind that finally overthrows them, they
+fall in the direction of the over-balancing top weight. The young
+trees grow spiry and perfectly upright, but as soon as they overtop
+the surrounding trees and get the full influence of the sun and wind,
+the highest branches grow out laterally, killing those beneath their
+shade, and thus a dome-shaped top is produced. Taking into
+consideration the health and vigor of the largest trees, it seems
+probable that, under favorable conditions of shelter from violent
+winds, and from a number of trees around them of nearly equal height,
+big trees might be produced far surpassing in height and bulk any that
+have yet been discovered. It is to be hoped that if any such are found
+to exist in the extensive groves of these trees to the south of those
+which are alone accessible to tourists, the Californian Government
+will take steps to reserve a considerable tract containing them, for
+the instruction and delight of future generations.
+
+The scarcity of young Sequoias strikes every visitor, the fact being
+that they are only to be found in certain favored spots. These are,
+either where the loose débris of leaves and branches which covers the
+ground has been cleared away by fire, or on the spots where trees have
+been uprooted. Here the young trees grow in abundance, and serve to
+replace those that fall. The explanation of this is, that during the
+long summer drought the loose surface débris is so dried up that the
+roots of the seedling Sequoias perish before they can penetrate the
+earth beneath. They require to germinate on the soil itself, and this
+they are enabled to do when the earth is turned up by the fall of a
+tree, or where a fire has cleared off the débris. They also flourish
+under the shade of the huge fallen trunks in hollow places, where
+moisture is preserved throughout the summer. Most of the other
+conifers of these forests, especially the pines, have much larger
+seeds than the Sequoias, and the store of nourishment in these more
+bulky seeds enables the young plants to tide over the first summer's
+drought. It is clear, therefore, that there are no indications of
+natural decay in these forest giants. In every stage of their growth
+they are vigorous and healthy, and they have nothing to fear except
+from the destroying hand of man.
+
+[Illustration: REDWOOD TREE WITH TRIPLE TRUNK.]
+
+Destruction from this cause is, however, rapidly diminishing both the
+giant Sequoia and its near ally the noble redwood (_Sequoia
+sempervirens_), a tree which is more beautiful in foliage and in some
+other respects more remarkable than its brother species, while there
+is reason to believe that under favorable conditions it reaches an
+equally phenomenal size. It once covered almost all the coast ranges
+of central and northern California, but has been long since cleared
+away in the vicinity of San Francisco, and greatly diminished
+elsewhere. A grove is preserved for the benefit of tourists near Santa
+Cruz, the largest tree being two hundred and ninety-six feet high,
+twenty-nine feet diameter at the ground and fifteen feet at six feet
+above it. One of these trees having a triple trunk is here figured
+from a photograph. Much larger trees, however, exist in the great
+forests of this tree in the northern part of the State; but these are
+rapidly being destroyed for the timber, which is so good and durable
+as to be in great demand. Hence Californians have a saying that the
+redwood is too good a tree to live. On the mountains a few miles east
+of the Bay of San Francisco, there are a number of patches of young
+redwoods, indicating where large trees have been felled, it being a
+peculiarity of this tree that it sends up vigorous young plants from
+the roots of old ones immediately around the base. Hence in the
+forests these trees often stand in groups arranged nearly in a circle,
+thus marking out the size of the huge trunks of their parents. It is
+from this quality that the tree has been named _sempervirens_, or ever
+flourishing. Dr. Gibbons, of Alameda, who has explored all the remains
+of the redwood forests in the neighborhood of Oakland, kindly took me
+to see the old burnt-out stump of the largest tree he had discovered.
+It is situated about fifteen hundred feet above the sea, and is
+thirty-four feet in diameter at the ground. This is as large as the
+very largest specimens of the _Sequoia gigantea_, but it may have
+spread out more at the base and have been somewhat smaller above,
+though this is not a special characteristic of the species.
+
+[Illustration]
+
+
+
+
+WHAT IS EVOLUTION?
+
+(FROM THE ATLANTIC MONTHLY, MARCH, '93.)
+
+BY PROFESSOR E.S. HOLDEN.
+
+
+[Illustration]
+
+I was once trying to tell a boy, a friend of mine, what the scientific
+men mean by the long word _Evolution_, and to give him some idea of
+the plan of the world. I wanted an illustration of something that had
+grown--evolved, developed--from small beginnings up through more and
+more complicated forms, till it had reached some very complete form. I
+could think of no better example than the railway by which we were
+sitting. The trains were running over the very track where a
+wagon-road had lately been, and before that a country cart-track, and
+before that a bridle-path, and before that again a mere trail for
+cattle. So I took the road for an example, and tried to show my boy
+how it had grown from little things by slow degrees according to laws;
+and if you like, I will try to tell it again.
+
+Just as one can go further and further back, and always find a bird to
+be the parent of the egg, and an egg to be the parent of that bird, so
+in the history of this road of ours; we may go back and back into the
+past, always finding something earlier, which is the cause of the
+something later. The earth, the planets, and the sun were all a fiery
+mist long ago. And in that mist, and in what came before it, we may
+look for the origin of things as they are. But we must begin
+somewhere. Let us begin with the landscape as we see it now,--hills,
+valleys, streams, mountains, grass,--but with only a single tree.
+
+We will not try to say how the tree came there. At least, we will not
+try just yet. When we are through with the story you can say just as
+well as I can.
+
+Suppose, then, a single oak-tree stood just on that hillside thousands
+and thousands of years ago. Grass was growing everywhere, and flowers,
+too. The seeds came with the winds. Year after year the oak-tree bore
+its acorns, hundreds and hundreds of them, and they fell on the grass
+beneath and rolled down the smooth slopes, and sprouted as best they
+could,--most of them uselessly so far as producing trees were
+concerned,--but each one did its duty and furnished its green sprout,
+and died if it found no nourishment.
+
+All the hundreds of acorns rolled down the slopes, Not one rolled up;
+and here was a _law_,--the law of gravitation,--in full activity.
+There were scores of other laws active, too; for evolution had gone a
+long way when we had an earth fit to be lived on, and hills in their
+present shape, and a tree bearing acorns that would reproduce their
+kind. But ever since the fiery mist this simple law of gravitation has
+been acting, binding the whole universe together, making a
+relationship between each clod and every other clod, and forcing
+every stone, every acorn, and every rain-drop to move down and not up.
+
+Just as this law operates,--continuously, silently, inexorably,--so
+every other law makes itself felt in its own sphere. Gravitation is
+simple. The law according to which an acorn makes an oak--and not a
+pine-tree is complex. But the laws of Nature are all alike, and if we
+understand the simple ones, we can at least partly comprehend the more
+complex. They are nothing but fixed habits on a large scale.
+
+So the acorns fell year by year and sprouted; and one out of a
+thousand found good soil, and was not wasted, and made a tree. And so
+all around (below) the tree with which we started there grew a grove
+of oaks like it, in fact its children; and finally the original trees
+died, but not without having left successors.
+
+First of all, the green hillside is smooth and untrodden. There is
+nothing but grass and flowers, borne there by the winds, which leave
+no track. There is no animal life even in this secluded spot save the
+birds, and they too leave no track. By and by there comes a hard
+winter, or a dearth of food, and a pair of stray squirrels emigrate
+from their home in the valley below; and the history of our hill and
+its woods begins. Mere chance decides the choice of the particular
+oak-tree in which the squirrels make their home. From the foot of this
+tree they make excursions here and there for their store of winter
+food,--acorns and the like,--and they leave little paths on the
+hillside from tree to tree.
+
+The best-marked paths run to the places where there are the most
+acorns. A little later on there are more squirrels in the colony,--the
+young of the parent pair, and other colonists from the valley. The
+little tracks become plainer and plainer.
+
+Later still come other wild animals in search of food,--squirrels will
+do. The wild animals do not remain in the colony (there are too few
+squirrels, and they are too hard to catch), but they pass through it,
+sometimes by day but oftenest by night.
+
+You might think it was perfectly a matter of chance along which path a
+bear or a wolf passed, but it was not. He _could_ walk anywhere on the
+hillside; and sometimes he would be found far out of the paths that
+the squirrels had begun. But usually, when he was in no haste, he took
+the easiest path. The easiest one was that which went between the
+bushes and not through them; along the hillside and not straight up
+it; around the big rocks and not over them. The wolves and bears and
+foxes have new and different wants when they come; and they break new
+paths to the springs where they drink, to the shade where they lie, to
+the hollow trees where the bees swarm and store the wild honey.
+
+But the squirrels were the first surveyors of these tracks. The bears
+and wolves are the engineers, who change the early paths to suit their
+special convenience.
+
+By and by the Indian hunter comes to follow the wild game. He, too,
+takes the easiest trail, the path of least resistance; and he follows
+the track to the spring that the deer have made, and he drinks there.
+He is an animal as they are, and he satisfies his animal wants
+according to the same law that governs them.
+
+After generations of hunters, Indians, and then white men, there comes
+a man on horseback looking for a house to live in. He, too, follows
+along the easiest paths and stops at the spring; and near by he finds
+the place he is looking for. Soon he returns, driving before him herds
+of cattle and flocks of sheep, which spread over the grassy glades to
+feed. But everywhere they take the easiest place, the old paths, from
+the shady tree to the flowing spring. After awhile the hillside is
+plainly marked with these sheep trails. You can see them now whenever
+you go into the country, on every hillside.
+
+Soon there are neighbors who build their homes in the next valley, and
+a good path must be made between the different houses.
+
+A few days' work spent in moving the largest stones, in cutting down
+trees, and in levelling off a few steep slopes, makes a trail along
+which you can gallop your horse.
+
+Things move fast now,--history begins to be made quickly as soon as
+man takes a hand in it. Soon the trail is not enough: it must be
+widened so that a wagon-load of boards for a new house can be carried
+in (for the settler has found a wife). After the first cart-track is
+made to carry the boards and shingles in, a better road will be needed
+to haul firewood and grain out (for the wants of the new family have
+increased, and things must be bought in the neighboring village with
+money, and money can only be had by selling the products of the farm).
+By and by the neighborhood is so well inhabited that it is to the
+advantage of the villages all around it to have good and safe and easy
+roads there; and the road is declared a public one, and it is
+regularly kept in repair and improved at the public expense. Do not
+forget the squirrels of long ago. They were the projectors of this
+road. Their successors use it now,--men and squirrels alike,--and stop
+at the spring to drink, and under the huge oaks to rest.
+
+A few years more, and it becomes to the advantage of all to have a
+railway through the valley and over the hillside. Then a young
+surveyor, just graduated from college, comes with his chain-men and
+flag-men, and finds that the squirrels, and bears, and hunters, and
+all the rest have picked out the easiest way for him long centuries
+ago. He makes his map, and soon the chief enigneer and the president
+of the road drive along in a buggy with a pair of fast horses
+(frightening the little squirrels off their road-way and into their
+holes), and the route of the Bear Valley and Quercus Railway is
+finally selected, and here it is. See! there comes a train along the
+track. This is the way a railway route grew out of a squirrel path.
+There are thousands of little steps, but you can trace them, or
+imagine them, as well as I can tell you.
+
+It is the same all over the world. Stanley cut a track through the
+endless African forests. But it lay between the Pygmy villages, along
+the paths they had made, and through the glades where they fought
+their battles with the storks.
+
+Sometimes the first road is a river--the track is already cut. Try to
+find out where the settlements in America were in the very early
+days--before 1800. You will find them along the Hudson, the Juanita,
+the St. Lawrence, the James, the Mississippi Rivers. But when these
+are left, men follow the squirrel-tracks and bear-tracks, or the
+paths of hunters, or the roads of Roman soldiers. It is a standing
+puzzle to little children why all the great rivers flow past the great
+towns. (Why do they?) The answer to that question will tell you why
+the great battles are fought in the same regions; why Egypt has been
+the coveted prize of a dozen different conquerors (it is the gateway
+of the East); why our Civil War turned on the possession of the
+Mississippi River. It is the roadways we fight for, the ways in and
+out, whether they be land or water. Of course, we really fought for
+something better than the mere possession of a roadway, but to get
+what we fought for we had to have the roadway first.
+
+The great principle at the bottom of everything in Nature is that the
+fittest survives: or, as I think it is better to say it, in any
+particular conflict or struggle that thing survives which is the
+fittest to survive _in this particular struggle_. This is Mr. Darwin's
+discovery,--or one of them,--and the struggle for existence is a part
+of the great struggle of the whole universe, and the laws of it make
+up the methods of Evolution--of Development.
+
+It is clear now, is it not, how the railway route is the direct
+descendant of the tiny squirrel track between two oaks? The process of
+development we call Evolution, and you can trace it all around you.
+Why are your skates shaped in a certain way? Why is your gun rifled?
+Why have soldiers two sets of (now) useless buttons on the skirts of
+their coats? (I will give you three guesses for this, and the hint
+that you must think of cavalry soldiers.) Why are eagles' wings of
+just the size that they are? These and millions of like questions are
+to be answered by referring to the principle of development.
+
+Sometimes it is hard to find the clew. Sometimes the development has
+gone so far, and the final product has become so complex and special,
+that it takes a good deal of thinking to find out the real reasons.
+But they _can_ be found, whether they relate to a fashion, to one of
+the laws of our country, or to the colors on a butterfly's wing.
+
+There is a little piece of verse intended to be comic, which, on the
+contrary, is really serious and philosophical, if you understand it.
+Learn it by heart, and apply it to all kinds and conditions of things,
+and see if it does not help you to explain them to yourself....
+
+  "And Man grew a thumb for that he had need of it,
+  And developed capacities for prey.
+  For the fastest men caught the most animals,
+  And the fastest animals got away from the most men.
+  Whereby all the slow animals were eaten,
+  And all the slow men starved to death."
+
+[Illustration]
+
+
+
+
+HOW THE SOIL IS MADE
+
+(FROM THE FORMATION OF VEGETABLE MOULD.)
+
+BY CHARLES DARWIN.
+
+
+[Illustration: W]
+
+Worms have played a more important part in the history of the world
+than most persons would at first suppose. In almost all humid
+countries they are extraordinarily numerous, and for their size
+possess great muscular power. In many parts of England a weight of
+more than ten tons (10,516 kilogrammes) of dry earth annually passes
+through their bodies and is brought to the surface on each acre of
+land; so that the whole superficial bed of vegetable mould passes
+through their bodies in the course of every few years. From the
+collapsing of the old burrows the mould is in constant though slow
+movement, and the particles composing it are thus rubbed together. By
+these means fresh surfaces are continually exposed to the action of
+the carbonic acid in the soil, and of the humus-acids which appear to
+be still more efficient in the decomposition of rocks. The generation
+of the humus-acids is probably hastened during the digestion of the
+many half-decayed leaves which worms consume. Thus the particles of
+earth, forming the superficial mould, are subjected to conditions
+eminently favorable for their decomposition and disintegration.
+Moreover, the particles of the softer rocks suffer some amount of
+mechanical trituration in the muscular gizzards of worms, in which
+small stones serve as mill-stones.
+
+[Illustration: DIAGRAM OF THE ALIMENTARY CANAL OF AN EARTH-WORM.]
+
+The finely levigated castings, when brought to the surface in a moist
+condition, flow during rainy weather down any moderate slope; and the
+smaller particles are washed far down even a gently inclined surface.
+Castings when dry often crumble into small pellets and these are apt
+to roll down any sloping surface. Where the land is quite level and is
+covered with herbage, and where the climate is humid so that much dust
+cannot be blown away, it appears at first sight impossible that there
+should be any appreciable amount of sub-aerial denudation; but worm
+castings are blown, especially while moist and viscid, in one uniform
+direction by the prevalent winds which are accompanied by rain. By
+these several means the superficial mould is prevented from
+accumulating to a great thickness; and a thick bed of mould checks in
+many ways the disintegration of the underlying rocks and fragments of
+rock.
+
+[Illustration: A WORM CASTING, FROM NICE. (Natural Size.)]
+
+The removal of worm-castings by the above means leads to results which
+are far from insignificant. It has been shown that a layer of earth,.2
+of an inch in thickness, is in many places annually brought to the
+surface per acre; and if a small part of this amount flows, or rolls,
+or is washed, even for a short distance, down every inclined surface,
+or is repeatedly blown in one direction, a great effect will be
+produced in the course of ages. It was found by measurements and
+calculations that on a surface with a mean inclination of 9° 26', 2.4
+cubic inches of earth which had been ejected by worms crossed, in the
+course of a year, a horizontal line one yard in length; so that two
+hundred and forty cubic inches would cross a line one hundred yards in
+length. This latter amount in a damp state would weigh eleven and
+one-half pounds. Thus, a considerable weight of earth is continually
+moving down each side of every valley, and will in time reach its bed.
+Finally, this earth will be transported by the streams flowing in the
+valleys into the ocean, the great receptacle for all matter denuded
+from the land. It is known from the amount of sediment annually
+delivered into the sea by the Mississippi, that its enormous
+drainage-area must on an average be lowered.00263 of an inch each
+year; and this would suffice in four and a half million years to lower
+the whole drainage-area to the level of the seashore. So that if a
+small fraction of the layer of fine earth,.2 of an inch in thickness,
+which is annually brought to the surface by worms, is carried away, a
+great result cannot fail to be produced within a period which no
+geologist considers extremely long.
+
+[Illustration: SECTION THROUGH ONE OF THE DRUIDICAL STONES AT
+STONEHENGE, SHOWING HOW MUCH IT HAD SUNK INTO THE GROUND.
+
+(Scale, 1/2 inch to 1 foot.)]
+
+Archaeologists ought to be grateful to worms, as they protect and
+preserve for an indefinitely long period every object, not liable to
+decay, which is dropped on the surface of the land, by burying it
+beneath their castings. Thus, also, many elegant and curious
+tesselated pavements and other ancient remains have been preserved;
+though no doubt the worms have in these cases been largely aided by
+earth washed and blown from the adjoining land, especially when
+cultivated. The old tesselated pavements have, however, often suffered
+by having subsided unequally from being unequally undermined by the
+worms. Even old massive walls may be undermined and subside; and no
+building is in this respect safe, unless the foundations lie six or
+seven feet beneath the surface, at a depth at which worms cannot work.
+It is probable that many monoliths and some old walls have fallen
+down from having been undermined by worms.
+
+Worms prepare the ground in an excellent manner for the growth of
+fibrous-rooted plants and for seedlings of all kinds. They
+periodically expose the mould to the air, and sift it so that no
+stones larger than the particles which they can swallow are left in
+it. They mingle the whole intimately together, like a gardener who
+prepares fine soil for his choicest plants. In this state it is well
+fitted to retain moisture and to absorb all soluble substances, as
+well as for the process of nitrification. The bones of dead animals,
+the harder parts of insects, the shells of land mollusks, leaves,
+twigs, etc., are before long all buried beneath the accumulated
+castings of worms, and are thus brought in a more or less decayed
+state within reach of the roots of plants. Worms likewise drag an
+infinite number of dead leaves and other parts of plants into their
+burrows, partly for the sake of plugging them up and partly as food.
+
+The leaves which are dragged into the burrows as food, after being
+torn into the finest shreds, partially digested and saturated with the
+intestinal and urinary secretions, are commingled with much earth.
+This earth forms the dark-colored, rich humus which almost everywhere
+covers the surface of the land with a fairly well-defined layer or
+mantle. Von Hensen placed two worms in a vessel eighteen inches in
+diameter, which was filled with sand, on which fallen leaves were
+strewed; and these were soon dragged into their burrows to a depth of
+three inches. After about six weeks an almost uniform layer of sand, a
+centimetre (.4 inch) in thickness, was converted into humus by having
+passed through the alimentary canals of these two worms. It is
+believed by some persons that worm-burrows, which often penetrate the
+ground almost perpendicularly to a depth of five or six feet,
+materially aid in its drainage; notwithstanding that the viscid
+castings piled over the mouths of the burrows prevent or check the
+rain-water directly entering them. They allow the air to penetrate
+deeply into the ground. They also greatly facilitate the downward
+passage of roots of moderate size; and these will be nourished by the
+humus with which the burrows are lined. Many seeds owe their
+germination to having been covered by castings; and others buried to a
+considerable depth beneath accumulated castings lie dormant, until at
+some future time they are accidentally uncovered and germinate.
+
+[Illustration: A WORM CASTING FROM SOUTH INDIA. (Natural Size.)]
+
+Worms are poorly provided with sense-organs, for they cannot be said
+to see, although they can just distinguish between light and darkness;
+they are completely deaf, and have only a feeble power of smell; the
+sense of touch alone is well developed. They can, therefore, learn
+little about the outside world, and it is surprising that they should
+exhibit some skill in lining their burrows with their castings and
+with leaves, and in the case of some species in piling up their
+castings into tower-like constructions. But it is far more surprising
+that they should apparently exhibit some degree of intelligence
+instead of a mere blind, instinctive impulse, in their manner of
+plugging up the mouths of their burrows. They act in nearly the same
+manner as would a man, who had to close a cylindrical tube with
+different kinds of leaves, petioles, triangles of paper, etc., for
+they commonly seize such objects by their pointed ends. But with thin
+objects a certain number are drawn in by their broader ends. They do
+not act in the same unvarying manner in all cases, as do most of the
+lower animals; for instance, they do not drag in leaves by their
+foot-stalks, unless the basil part of the blade is as narrow as the
+apex, or narrower than it.
+
+       *       *       *       *       *
+
+When we behold a wide, turf-covered expanse, we should remember that
+its smoothness, on which so much of its beauty depends, is mainly due
+to all the inequalities having been slowly levelled by worms. It is a
+marvellous reflection that the whole of the superficial mould over any
+such expanse has passed, and will again pass, every few years through
+the bodies of worms. The plough is one of the most ancient and most
+valuable of man's inventions; but long before he existed the land was
+in fact regularly ploughed, and, still continues to be thus ploughed
+by earth-worms. It may be doubted whether there are many other animals
+which have played so important a part in the history of the world, as
+have these lowly organized creatures. Some other animals, however,
+still more lowly organized, namely, corals, have done far more
+conspicuous work in having constructed innumerable reefs and islands
+in the great oceans; but these are almost confined to the tropical
+zones.
+
+[Illustration]
+
+
+
+
+ZOÖLOGICAL MYTHS
+
+(FROM FACTS AND FICTIONS OF ZOÖLOGY.)
+
+BY ANDREW WILSON.
+
+
+[Illustration]
+
+When the country swain, loitering along some lane, comes to a
+standstill to contemplate, with awe and wonder, the spectacle of a
+mass of the familiar "hair-eels" or "hair-worms" wriggling about in a
+pool, he plods on his way firmly convinced that, as he has been taught
+to believe, he has just witnessed the results of the transformation of
+some horse's hairs into living creatures. So familiar is this belief
+to people of professedly higher culture than the countryman, that the
+transformation just alluded to has to all, save a few thinking persons
+and zoölogists, become a matter of the most commonplace kind. When
+some quarrymen, engaged in splitting up the rocks, have succeeded in
+dislodging some huge mass of stone, there may sometimes be seen to hop
+from among the débris a lively toad or frog, which comes to be
+regarded by the excavators with feelings akin to those of
+superstitious wonder and amazement. The animal may or may not be
+captured; but the fact is duly chronicled in the local newspapers, and
+people wonder for a season over the phenomenon of a veritable Rip Van
+Winkle of a frog, which to all appearance, has lived for "thousands of
+years in the solid rock." Nor do the hair-worm and the frog stand
+alone in respect of their marvellous origin. Popular zoölogy is full
+of such marvels. We find unicorns, mermaids, and mermen; geese
+developed from the shell-fish known as "barnacles"; we are told that
+crocodiles may weep, and that sirens can sing--in short, there is
+nothing so wonderful to be told of animals that people will not
+believe the tale. Whilst, curiously enough, when they are told of
+veritable facts of animal life, heads begin to shake and doubts to be
+expressed, until the zoölogist despairs of educating people into
+distinguishing fact from fiction, and truth from theories and
+unsupported beliefs. The story told of the old lady, whose youthful
+acquaintance of seafaring habits entertained her with tales of the
+wonders he had seen, finds, after all, a close application in the
+world at large. The dame listened with delight, appreciation, and
+belief, to accounts of mountains of sugar and rivers of rum, and to
+tales of lands where gold and silver and precious stones were more
+than plentiful. But when the narrator descended to tell of fishes that
+were able to raise themselves out of the water in flight, the old
+lady's credulity began to fancy itself imposed upon; for she
+indignantly repressed what she considered the lad's tendency to
+exaggeration, saying, "Sugar mountains may be, and rivers of rum may
+be, but fish that flee ne'er can be!" Many popular beliefs concerning
+animals partake of the character of the old lady's opinions regarding
+the real and fabulous; and the circumstance tells powerfully in favor
+of the opinion that a knowledge of our surroundings in the world, and
+an intelligent conception of animal and plant life, should form part
+of the school-training of every boy and girl, as the most effective
+antidote to superstitions and myths of every kind.
+
+
+[Illustration: FLYING FISH.]
+
+The tracing of myths and fables is a very interesting task, and it
+may, therefore, form a curious study, if we endeavor to investigate
+very briefly a few of the popular and erroneous beliefs regarding
+lower animals. The belief regarding the origin of the hair-worms is
+both widely spread and ancient. Shakespeare tells us that
+
+                                  "Much, is breeding
+  Which, like the courser's hair, hath, yet but life,
+  And not a serpent's poison."
+
+The hair-worms certainly present the appearance of long, delicate
+black hairs, which move about with great activity amidst the mud of
+pools and ditches. These worms, in the early stages of their
+existence, inhabit the bodies of insects, and may be found coiled up
+within the grasshopper, which thus gives shelter to a guest exceeding
+many times the length of the body of its host. Sooner or later the
+hair-worm, or _Gordius aquaticus_ as the naturalist terms it, leaves
+the body of the insect, and lays its eggs, fastened together in long
+strings, in water. From each egg a little creature armed with minute
+hooks is produced, and this young hair-worm burrows its way into the
+body of some insect, there to repeat the history of its parent. Such
+is the well-ascertained history of the hair-worm, excluding entirely
+the popular belief in its origin. There certainly does exist in
+science a theory known as that of "spontaneous generation," which, in
+ancient times, accounted for the production of insects and other
+animals by assuming that they were produced in some mysterious fashion
+out of lifeless matter. But not even the most ardent believer in the
+extreme modification of this theory which holds a place in modern
+scientific belief, would venture to maintain the production of a
+hair-worm by the mysterious vivification of an inert substance such as
+a horse's hair.
+
+The expression "crocodile's tears" has passed into common use, and it
+therefore may be worth while noting the probable origin of this myth.
+Shakespeare, with that wide extent of knowledge which enabled him to
+draw similes from every department of human thought, says that
+
+                          "Gloster's show
+  Beguiles him, as the mournful crocodile
+  With sorrow snares relenting passengers."
+
+The poet thus indicates the belief that not only do crocodiles shed
+tears, but that sympathizing passengers, turning to commiserate the
+reptile's woes, are seized and destroyed by the treacherous creatures.
+That quaint and credulous old author--the earliest writer of English
+prose--Sir John Mandeville, in his "Voiage," or account of his
+"Travile," published about 1356--in which, by the way, there are to be
+found accounts of not a few wonderful things in the way of zoölogical
+curiosities--tells us that in a certain "contre and be all yonde, ben
+great plenty of Crokodilles, that is, a manner of a long Serpent as I
+have seyed before." He further remarks that "these Serpents slew men,"
+and devoured them, weeping; and he tells us, too, that "whan thei
+eaten thei meven (move) the over jowe (upper jaw), and nought the
+nether (lower) jowe: and thei have no tonge (tongue)." Sir John thus
+states two popular beliefs of his time and of days prior to his age,
+namely, that crocodiles move their upper jaws, and that a tongue was
+absent in these animals.
+
+[Illustration: CROCODILE.]
+
+As regards the tears of the crocodile, no foundation of fact exists
+for the belief in such sympathetic exhibitions. But a highly probable
+explanation may be given of the manner in which such a belief
+originated. These reptiles unquestionably emit very loud and
+singularly plaintive cries, compared by some travellers to the
+mournful howling of dogs. The earlier and credulous travellers would
+very naturally associate tears with these cries, and, once begun, the
+supposition would be readily propagated, for error and myth are ever
+plants of quick growth. The belief in the movement of the upper jaw
+rests on apparent basis of fact. The lower jaw is joined to the skull
+very far back on the latter, and the mouth-opening thus comes to be
+singularly wide; whilst, when the mouth opens, the skull and upper jaw
+are apparently observed to move. This is not the case, however; the
+apparent movement arising from the manner in which the lower jaw and
+the skull are joined together. The belief in the absence of the tongue
+is even more readily explained. When the mouth is widely opened, no
+tongue is to be seen. This organ is not only present, but is,
+moreover, of large size; it is, however, firmly attached to the floor
+of the mouth, and is specially adapted, from its peculiar form and
+structure, to assist these animals in the capture and swallowing of
+their prey.
+
+One of the most curious fables regarding animals which can well be
+mentioned, is that respecting the so-called "Bernicle" or "Barnacle
+Geese," which by the naturalists and educated persons of the Middle
+Ages were believed to be produced by those little Crustaceans named
+"Barnacles." With the "Barnacles" every one must be familiar who has
+examined the floating driftwood of the sea-beach, or who has seen
+ships docked in a seaport town. A barnacle is simply a kind of crab
+enclosed in a triangular shell, and attached by a fleshy stalk to
+fixed objects. If the barnacle is not familiar to readers, certain
+near relations of these animals must be well known, by sight at least,
+as amongst the most familiar denizens of our sea-coast. These latter
+are the "Sea-Acorn," or Balani, whose little conical shells we crush
+by hundreds as we walk over the rocks at low-water mark; whilst every
+wooden pile immersed in the sea becomes coated in a short time with a
+thick crust of the "Sea-Acorns." If we place one of these little
+animals, barnacle, or sea-acorn--the latter wanting the stalk of the
+former--in its native waters, we shall observe a beautiful little
+series of feathery plumes to wave backward and forward, and ever and
+anon to be quickly withdrawn into the secure recesses of the shell.
+These organs are the modified feet of the animal, which not only serve
+for sweeping food-particles into the mouth, but act also as
+breathing-organs. We may, therefore, find it a curious study to
+inquire through what extraordinary transformation and confusion of
+ideas such an animal could be credited with giving origin to a
+veritable goose; and the investigation of the subject will also afford
+a singularly apt illustration of the ready manner in which the fable
+of one year or period becomes transmitted and transformed into the
+secure and firm belief of the next.
+
+We may begin our investigation by inquiring into some of the opinions
+which were entertained on this subject and ventilated by certain old
+writers. Between 1154 and 1189 Giraldus Cambrensis, in a work entitled
+"Topographia Hiberniae," written in Latin, remarks concerning "many
+birds which are called Bernacae: against nature, nature produces them
+in a most extraordinary way. They are like marsh geese, but somewhat
+smaller. They are produced from fir timber tossed along the sea, and
+are at first like gum. Afterward they hang down by their beaks, as if
+from a seaweed attached to the timber, surrounded by shells, in order
+to grow more freely," Giraldus is here evidently describing the
+barnacles themselves. He continues: "Having thus, in process of time,
+been clothed with a strong coat of feathers, they either fall into the
+water or fly freely away into the air. They derive their food and
+growth from the sap of the wood or the sea, by a secret and most
+wonderful process of alimentation. I have frequently, with my own
+eyes, seen more than a thousand of these small bodies of birds,
+hanging down on the seashore from one piece of timber, enclosed in
+shells, and already formed." Here, again, our author is speaking of
+the barnacles themselves, with which he naturally confuses the geese,
+since he presumes the Crustaceans are simply geese in an undeveloped
+state. He further informs his readers that, owing to their presumably
+marine origin, "bishops and clergymen in some parts of Ireland do not
+scruple to dine off these birds at the time of fasting, because they
+are not flesh, nor born of flesh," although for certain other and
+theological reasons, not specially requiring to be discussed in the
+present instance, Giraldus disputes the legality of this practice of
+the Hibernian clerics.
+
+In the year 1527 appeared "The Hystory and Croniclis of Scotland, with
+the cosmography and dyscription thairof, compilit be the noble Clerk
+Maister Hector Boece, Channon of Aberdene." Boece's "History" was
+written in Latin; the title we have just quoted being that of the
+English version of the work (1540), which title further sets forth
+that Boece's work was "Translait laitly in our vulgar and commoun
+langage be Maister Johne Bellenden, Archedene of Murray, And
+Imprentit in Edinburgh, be me Thomas Davidson, prenter to the Kyngis
+nobyll grace." In this learned work the author discredits the popular
+ideas regarding the origin of the geese. "Some men belevis that thir
+clakis (geese) growis on treis be the nebbis (bills). Bot thair
+opinoun is vane. And becaus the nature and procreatioun of thir clakis
+is strange, we have maid na lytyll laboure and deligence to serche ye
+treuth and verite yairof, we have salit (sailed) throw ye seis quhare
+thir clakis ar bred, and I fynd be gret experience, that the nature of
+the seis is mair relevant caus of thair procreatioun than ony uthir
+thyng." According to Boece, then, "the nature of the seis" formed the
+chief element in the production of the geese, and our author proceeds
+to relate how "all treis (trees) that ar casein in the seis be proces
+of tyme apperis first wormeetin (worm-eaten), and in the small boris
+and hollis (holes) thairof growis small worms." Our author no doubt
+here alludes to the ravages of the Teredo, or ship-worm, which burrows
+into timber, and with which the barnacles themselves are thus
+confused. Then he continues, the "wormis" first "schaw (show) thair
+heid and feit, and last of all thay schaw thair plumis and wyngis.
+Finaly, quhen thay ar cumyn to the just mesure and quantite of geis,
+thay fle in the aire as othir fowlis dois, as was notably provyn, in
+the yeir of God ane thousand iii hundred lxxxx, in sicht of mony
+pepyll, besyde the castell of Petslego." On the occasion referred to,
+Boece tells us that a great tree was cast on shore, and was divided,
+by order of the "laird" of the ground, by means of a saw. Wonderful to
+relate, the tree was found not merely to be riddled with a "multitude
+of wormis," throwing themselves out of the holes of the tree, but some
+of the "wormis" had "baith heid, feit, and wyngis," but, adds the
+author, "they had no fedderis (feathers)."
+
+Unquestionably, either "the scientific use of the imagination" had
+operated in this instance in inducing the observers to believe that in
+this tree, riddled by the ship-worms and possibly having barnacles
+attached to it, they beheld young geese; or Boece had construed the
+appearances described as those representing the embryo stages of the
+barnacle geese.
+
+Boece further relates how a ship named the Christofir was brought to
+Leith, and was broken down because her timbers had grown old and
+failing. In these timbers were beheld the same "wormeetin"
+appearances, "all the hollis thairof" being "full of geis." Boece
+again most emphatically rejects the idea that the "geis" were produced
+from the wood of which the timbers were composed, and once more
+proclaims his belief that the "nature of the seis resolvit in geis"
+may be accepted as the true and final explanation of their origin. A
+certain "Maister Alexander Galloway" had apparently strolled with the
+historian along the sea-coast, the former giving "his mynd with maist
+ernist besynes to serche the verite of this obscure and mysty dowtis."
+Lifting up a piece of tangle, they beheld the seaweed to be hanging
+full of mussel-shells from the root to the branches. Maister Galloway
+opened one of the mussel-shells, and was "mair astonis than afore" to
+find no fish therein, but a perfectly shaped "foule, smal and gret,"
+as corresponded to the "quantity of the shell." And once again Boece
+draws the inference that the trees or wood on which the creatures are
+found have nothing to do with the origin of the birds; and that the
+fowls are begotten of the "occeane see, quhilk," concludes our author,
+"is the caus and production of mony wonderful thingis."
+
+More than fifty years after the publication of Boece's "History," old
+Gerard of London, the famous "master in chirurgerie" of his day, gave
+an account of the barnacle goose, and not only entered into minute
+particulars of its growth and origin, but illustrated its manner of
+production by means of the engraver's art of his day. Gerard's
+"Herball," published in 1597, thus contains, amongst much that is
+curious in medical lore, a very quaint piece of zoölogical history. He
+tells us that "in the north parts of Scotland, and the Hands adjacent,
+called Orchades (Orkneys)," are found "certaine trees, whereon doe
+growe certaine shell fishes, of a white colour tending to russet;
+wherein are conteined little living creatures: which shels in time of
+maturitie doe open, and out of them grow those little living foules
+whom we call Barnakles, in the north of England Brant Geese, and in
+Lancashire tree Geese; but the other that do fall upon the land,
+perish, and come to nothing: thus much by the writings of others, and
+also from the mouths of people of those parts, which may," concludes
+Gerard, "very well accord with truth."
+
+Not content with hearsay evidence, however, Gerard relates what his
+eyes saw and hands touched. He describes how on the coasts of a
+certain "small Hand in Lancashire called Pile of Foulders" (probably
+Peel Island), the wreckage of ships is cast up by the waves, along
+with the trunks and branches "of old and rotten trees." On these
+wooden rejectamenta "a certaine spume or froth" grows, according to
+Gerard. This spume "in time breedeth unto certaine shels, in shape
+like those of the muskle, but sharper pointed, and of a whitish
+color." This description, it may be remarked, clearly applies to the
+barnacles themselves. Gerard then continues to point out how, when the
+shell is perfectly formed, it "gapeth open, and the first thing that
+appeereth is the foresaid lace or string"--the substance described by
+Gerard as contained within the shell--"next come the legs of the Birde
+hanging out; and as it groweth greater, it openeth the shell by
+degrees, till at length it is all come forth, and hangeth only by the
+bill; in short space after it commeth to full maturitie, and falleth
+into the sea, where it gathereth feathers, and groweth to a foule,
+bigger than a Mallard, and lesser than a Goose, having blacke legs and
+bill or beake, and feathers blacke and white ... which the people of
+Lancashire call by no other name than a tree Goose."
+
+[Illustration: FIG. 1. THE BARNACLE TREE. (From Gerard's "Herball.")]
+
+Accompanying this description is the engraving of the barnicle tree
+(Fig. 1) bearing its geese progeny. From the open shells in two cases,
+the little geese are seen protruding, whilst several of the
+fully-fledged fowls are disporting themselves in the sea below.
+Gerard's concluding piece of information, with its exordium, must not
+be omitted. "They spawne," says the wise apothecary, "as it were, in
+March or Aprill; the Geese are found in Maie or June, and come to
+fulnesse of feathers in the moneth after. And thus hauing, through
+God's assistance, discoursed somewhat at large of Grasses, Herbes,
+Shrubs, Trees, Mosses, and certaine excrescences of the earth, with
+other things moe incident to the Historic thereof, we conclude and end
+our present volume, with this woonder of England. For which God's name
+be euer honored and praised." It is to be remarked that Gerard's
+description of the goose-progeny of the barnacle tree exactly
+corresponds with the appearance of the bird known to ornithologists as
+the "barnacle-goose"; and there can be no doubt that, skilled as was
+this author in the natural history lore of his day, there was no other
+feeling in his mind than that of firm belief in and pious wonder at
+the curious relations between the shells and their fowl-offspring.
+Gerard thus attributes the origin of the latter to the barnacles. He
+says nothing of the "wormeetin" holes and burrows so frequently
+mentioned by Boece, nor would he have agreed with the latter in
+crediting the "nature of the occeane see" with their production, save
+in so far as their barnacle-parents lived and existed in the waters of
+the ocean.
+
+The last account of this curious fable which we may allude to in the
+present instance is that of Sir Robert Moray, who, in his work
+entitled "A Relation concerning Barnacles," published in the
+_Philosophical Transactions_ of the Royal Society in 1677-78, gives a
+succinct account of these crustaceans and their bird-progeny. Sir
+Robert is described as "lately one of his Majesties Council for the
+Kingdom of Scotland," and we may therefore justly assume his account
+to represent that of a cultured, observant person of his day and
+generation. The account begins by remarking that the "most ordinary
+trees" found in the western islands of Scotland "are Firr and Ash."
+"Being," continues Sir Robert, "in the Island of East (Uist), I saw
+lying upon the shore a cut of a large Firr tree of about 2-1/2 foot
+diameter, and 9 or 10 foot long; which had lain so long out of the
+water that it was very dry: And most of the shells that had formerly
+cover'd it, were worn or rubb'd off. Only on the parts that lay next
+the ground, there still hung multitudes of little Shells; having
+within them little Birds, perfectly shap'd, supposed to be Barnacles."
+Here again the description applies to the barnacles; the "little
+birds" they are described as containing being of course the bodies of
+the shell-fish.
+
+"The Shells," continues the narrator, "hang at the Tree by a Neck
+longer than the Shell;" this "neck" being represented by the stalk of
+the barnacle. The neck is described as being composed "of a kind of
+filmy substance, round, and hollow, and creased, not unlike the
+Wind-pipe of a Chicken; spreading out broadest where it is fastened to
+the Tree, from which it seems to draw and convey the matter which
+serves for the growth and vegetation of the Shell and the little Bird
+within it." Sir Robert Moray therefore agrees in respect of the manner
+of nourishment of the barnacles with the opinion of Giraldus already
+quoted. The author goes on to describe the "Bird" found in every
+shell he opened; remarking that "there appeared nothing wanting as to
+the internal parts, for making up a perfect Sea-fowl: every little
+part appearing so distinctly, that the whole looked like a large Bird
+seen through a concave or diminishing Glass, colour and feature being
+everywhere so clear and neat." The "Bird" is most minutely described
+as to its bill, eyes, head, neck, breast, wings, tail, and feet, the
+feathers being "everywhere perfectly shaped, and blackish-coloured.
+All being dead and dry," says Sir Robert, "I did not look after the
+Internal parts of them," a statement decidedly inconsistent with his
+previous assertion as to the perfect condition of the "internal
+parts"; and he takes care to add, "nor did I ever see any of the
+little Birds alive, nor met with anybody that did. Only some credible
+persons," he concludes, "have assured me they have seen some as big as
+their fist."
+
+[Illustration: FIG. 2. BARNACLE TREE. (From Munster's "Cosmography.")]
+
+This last writer thus avers that he saw little birds within the shells
+he clearly enough describes as those of the barnacles. We must either
+credit Sir Robert with describing what he never saw, or with
+misconstruing what he did see. His description of the goose
+corresponds with that of the barnacle goose, the reputed progeny of
+the shells; and it would, therefore, seem that this author, with the
+myth at hand, saw the barnacles only with the eyes of a credulous
+observer, and thus beheld, in the inside of each shell--if, indeed,
+his research actually extended thus far--the reproduction in miniature
+of a goose, with which, as a mature bird, he was well acquainted.
+
+On p. 157 is a woodcut, copied from Munster's "Cosmography" (1550), a
+very popular book in its time, showing the tree with its fruit, and
+the geese which are supposed to have just escaped from it.
+
+This historical ramble may fitly preface what we have to say regarding
+the probable origin of the myth. By what means could the barnacles
+become credited with the power of producing the well-known geese? Once
+started, the progress and growth of the myth are easily accounted for.
+The mere transmission of a fable from one generation or century to
+another is a simply explained circumstance, and one exemplified by the
+practices of our own times. The process of accretion and addition is
+also well illustrated in the perpetuation of fables; since the tale is
+certain to lose nothing in its historical journey, but, on the
+contrary, to receive additional elaboration with increasing age.
+Professor Max Müller, after discussing various theories of the origin
+of the barnacle myth, declares in favor of the idea that confusion of
+language and alteration of names lie at the root of the error. The
+learned author of the "Science of Language" argues that the true
+barnacles were named, properly enough, Bernaculae, and lays stress on
+the fact that Bernicle geese were first caught in Ireland. That
+country becomes _Hibernia_ in Latin, and the Irish geese were
+accordingly named Hibernicae, or Hiberniculae. By the omission of the
+first syllable--no uncommon operation for words to undergo--we obtain
+the name Berniculae for the geese, this term being almost synonymous
+with the name Bernaculae already applied, as we have seen, to the
+barnacles. Bernicle geese and bernicle shells, confused in name, thus
+became confused in nature; and, once started, the ordinary process of
+growth was sufficient to further intensify, and render more realistic,
+the story of the bernicle tree and its wonderful progeny.
+
+By way of a companion legend to that of the barnacle tree, we may
+select the story of the "Lamb Tree" of Cathay, told by Sir John
+Mandeville, whose notes of travel regarding crocodiles' tears, and
+other points in the conformation of these reptiles, have already been
+referred to. Sir John, in that chapter of his work which treats "Of
+the Contries and Yles that ben bezonde the Lond of Cathay; and of the
+Frutes there," etc., relates that in Cathay "there growethe a manner
+of Fruyt, as thoughe it were Gowrdes: and whan thei ben rype, men
+kutten (cut) hem a to (them in two), and men fyndem with inne a
+lytylle Best (beast), in Flessche in Bon and Blode (bone and blood) as
+though it were a lytylle Lomb (lamb) with outen wolle (without wool).
+And men eaten both the Frut and the Best; and that," says Sir John,
+"is a great marveylle. Of that frut," he continues, "I have eten; alle
+thoughe it were wondirfulle"--this being added, no doubt, from an
+idea that there might possibly be some stay-at-home persons who would
+take Sir John's statement _cum grano salis_. "But," adds this worthy
+"knyght of Ingolond," "I knowe wel that God is marveyllous in His
+Werkes." Not to be behind the inhabitants of Cathay in a tale of
+wonders, the knight related to these Easterns "als gret a marveylle to
+hem that is amonges us; and that was of the Bernakes. For I tolde him
+hat in oure Countree weren Trees that beren a Fruyt, that becomen
+Briddes (birds) fleeynge: and tho that fellen in the Water lyven
+(live); and thei that fallen on the Erthe dyen anon: and thei ben
+right gode to mannes mete (man's meat). And here had thei als gret
+marvayle," concludes Sir John, "that sume of hem trowed it were an
+impossible thing to be." Probably the inhabitants of Cathay, knowing
+their own weakness as regards the lamb tree, might possess a
+fellow-feeling for their visitor's credulity, knowing well, from
+experience, the readiness with which a "gret marvayle" could be
+evolved and sustained.
+
+Passing from the sphere of the mythical and marvellous as represented
+in mediaeval times, we may shortly discuss a question, which, of all
+others, may justly claim a place in the records of zoölogical
+curiosities--namely, the famous and oft-repeated story of the "Toad
+from the solid rock," as the country newspapers style the incident.
+Regularly, year by year, and in company with the reports of the
+sea-serpent's reappearance, we may read of the discoveries of toads
+and frogs in situations and under circumstances suggestive of a
+singular vitality on the part of the amphibians, of more than usual
+credulity on the part of the hearers, or of a large share of
+inventive genius in the narrators of such tales. The question
+possesses for every one a certain degree of interest, evoked by the
+curious and strange features presented on the face of the tales. And
+it may therefore not only prove an interesting but also a useful
+study, if we endeavor to arrive at some just and logical conceptions
+of these wonderful narrations.
+
+[Illustration]
+
+Instances of the discovery of toads and frogs in solid rocks need not
+be specially given; suffice it to say, that these narratives are
+repeated year by year with little variation. A large block of stone or
+face of rock is detached from its site, and a toad or frog is seen
+hereafter to be hopping about in its usual lively manner. The
+conclusion to which the bystanders invariably come is that the animal
+must have been contained within the rock, and that it was liberated by
+the dislodgement of the mass. Now, in many instances, cases of the
+appearance of toads during quarrying operations have been found, on
+close examination, to present no evidence whatever that the appearance
+of the animals was due to the dislodgement of the stones. A frog or
+toad may be found hopping about among some recently formed débris, and
+the animal is at once seized upon and reported as having emerged from
+the rocks into the light of day. There is in such a case not the
+slightest ground for supposing any such thing; and the animal may more
+reasonably be presumed to have simply hopped into the débris from its
+ordinary habitat. But laying aside narratives of this kind, which lose
+their plausibility under a very commonplace scrutiny, there still
+exist cases, reported in an apparently exact and truthful manner, in
+which these animals have been alleged to appear from the inner
+crevices of rocks after the removal of large masses of the formations.
+We shall assume these latter tales to contain a plain, unvarnished
+statement of what was observed, and deal with the evidence they
+present on this footing.
+
+[Illustration: A TOAD.]
+
+One or two notable examples of such verified tales are related by
+Smellie, in his "Philosophy of Natural History." Thus, in the "Memoirs
+of the French Academy of Sciences" for 1719, a toad is described as
+having been found in the heart of an elm tree; and another is stated
+to have been found in the heart of an old oak tree, in 1731, near
+Nantz. The condition of the trees is not expressly stated, nor are we
+afforded any information regarding the appearance of the
+toads--particulars of considerable importance in view of the
+suggestions and explanations to be presently brought forward. Smellie
+himself, while inclined to be sceptical in regard to the truth or
+exactness of many of the tales told of the vitality of toads, regards
+the matter as affording food for reflection, since he remarks, "But I
+mean not to persuade, for I cannot satisfy myself; all I intend is, to
+recommend to those gentlemen who may hereafter chance to see such rare
+phenomena, a strict examination of every circumstance that can throw
+light upon a subject so dark and mysterious; for the vulgar, ever
+inclined to render uncommon appearances still more marvellous, are not
+to be trusted."
+
+This author strikes the key-note of the inquiry in his concluding
+words, and we shall find that the explanation of the matter really
+lies in the clear understanding of what are the probabilities, and
+what the actual details, of the cases presented for consideration. We
+may firstly, then, glance at a few of the peculiarities of the frogs
+and toads, regarded from a zoölogical point of view. As every one
+knows, these animals emerge from the egg in the form of little
+fish-like "tadpoles," provided with outside gills, which are soon
+replaced by inside gills, resembling those of fishes. The hind legs
+are next developed, and the fore limbs follow a little later; whilst,
+with the development of lungs, and the disappearance of the gills and
+tail, the animal leaves the water, and remains for the rest of its
+life an air-breathing, terrestrial animal. Then, secondly, in the
+adult frog or toad, the naturalist would point to the importance of
+the skin as not only supplementing, but, in some cases, actually
+supplanting the work of the lungs as the breathing organ. Frogs and
+toads will live for months under water, and will survive the excision
+of the lungs for like periods; the skin in such cases serving as the
+breathing surface. A third point worthy of remembrance is included in
+the facts just related, and is implied in the information that these
+animals can exist for long periods without food, and with but a
+limited supply of air. We can understand this toleration on the part
+of these animals when we take into consideration their cold-blooded
+habits, which do not necessitate, and which are not accompanied by,
+the amount of vital activity we are accustomed to note in higher
+animals. And, as a last feature in the purely scientific history of
+the frogs and toads, it may be remarked that these animals are known
+to live for long periods. One pet toad is mentioned by a Mr. Arscott
+as having attained, to his knowledge, the age of thirty-six years; and
+a greater age still might have been recorded of this specimen, but for
+the untoward treatment it sustained at the hands, or rather beak, of a
+tame raven. In all probability it may be safely assumed that, when the
+conditions of life are favorable, these creatures may attain a highly
+venerable age--regarding the lapse of time from a purely human and
+interested point of view.
+
+We may now inquire whether or not the foregoing considerations may
+serve to throw any light upon the tales of the quarryman. The first
+point to which attention may be directed is that involved in the
+statement that the amphibian has been imprisoned in a _solid_ rock.
+Much stress is usually laid on the fact that the rock was solid; this
+fact being held to imply the great age, not to say antiquity, of the
+rock and its supposed tenant. The impartial observer, after an
+examination of the evidence presented, will be inclined to doubt
+greatly the justification for inserting the adjective "solid"; for
+usually no evidence whatever is forthcoming as to the state of the
+rock prior to its removal. No previous examination of the rock is or
+can be made, from the circumstance that no interest can possibly
+attach to its condition until its removal reveals the apparent wonder
+it contained, in the shape of the live toad. And it is equally
+important to note that we rarely, if ever, find mention of any
+examination of the rock being made subsequently to the discovery.
+Hence, a first and grave objection may be taken to the validity of the
+supposition that the rock was solid, and it may be fairly urged that
+on this supposition the whole question turns and depends. For if the
+rock cannot be proved to have been impermeable to and barred against
+the entrance of living creatures, the objector may proceed to show the
+possibility of the toad having gained admission, under certain notable
+circumstances, to its prison-house.
+
+The frog or toad in its young state, and having just entered upon its
+terrestrial life, is a small creature, which could, with the utmost
+ease, wriggle into crevices and crannies of a size which would almost
+preclude such apertures being noticed at all. Gaining access to a
+roomier crevice or nook within, and finding there a due supply of air,
+along with a dietary consisting chiefly of insects, the animal would
+grow with tolerable rapidity, and would increase to such an extent
+that egress through its aperture of entrance would become an
+impossibility. Next, let us suppose that the toleration of the toad's
+system to starvation and to a limited supply of air is taken into
+account, together with the fact that these creatures will hibernate
+during each winter, and thus economize, as it were, their vital
+activity and strength; and after the animal has thus existed for a
+year or two--no doubt under singularly hard conditions--let us imagine
+that the rock is split up by the wedge and lever of the excavator. We
+can then readily enough account for the apparently inexplicable story
+of "the toad in the rock." "There is the toad and here is the solid
+rock," say the gossips. "There is an animal which has singular powers
+of sustaining life under untoward conditions, and which, in its young
+state, could have gained admittance to the rock through a mere
+crevice," says the naturalist in reply. Doubtless, the great army of
+the unconvinced may still believe in the tale as told them; for the
+weighing of evidence and the placing _pros_ and _cons_ in fair
+contrast are not tasks of congenial or wonted kind in the ordinary run
+of life. Some people there will be who will believe in the original
+solid rock and its toad, despite the assertion of the geologists that
+the earliest fossils of toads appear in almost the last-formed rocks,
+and that a live toad in rocks of very ancient age--presuming,
+according to the popular belief, that the animal was enclosed when the
+rock was formed--would be as great an anomaly and wonder as the
+mention, as an historical fact, of an express train or the telegraph
+in the days of the patriarchs. In other words, the live toad which
+hops out of an Old Red Sandstone rock must be presumed, on the popular
+belief, to be older by untold ages than the oldest fossil frogs and
+toads. The reasonable mind, however, will ponder and consider each
+feature of the case, and will rather prefer to countenance a
+supposition based on ordinary experience, than an explanation brought
+ready-made from the domain of the miraculous; whilst not the least
+noteworthy feature of these cases is that included in the remark of
+Smellie, respecting the tendency of uneducated and superstitious
+persons to magnify what is uncommon, and in his sage conclusion that
+as a rule such persons in the matter of their relations "are not to be
+trusted."
+
+But it must also be noted that we possess valuable evidence of a
+positive and direct kind bearing on the duration of life in toads
+under adverse circumstances. As this evidence tells most powerfully
+against the supposition that the existence of those creatures can be
+indefinitely prolonged, it forms of itself a veritable court of appeal
+in the cases under discussion. The late Dr. Buckland, curious to learn
+the exact extent of the vitality of the toad, caused, in the year
+1825, two large blocks of stone to be prepared. One of the blocks was
+taken from the oölite limestone, and in this first stone twelve cells
+were excavated. Each cell was one foot deep and five inches in
+diameter. The mouth of each cell was grooved so as to admit of two
+covers being placed over the aperture; the first or lower cover being
+of glass, and the upper one of slate. Both covers were so adapted that
+they could be firmly luted down with clay or putty; the object of this
+double protection being that the slate cover could be raised so as to
+inspect the contained object through the closed glass cover without
+admitting air. In the second or sandstone block, a series of twelve
+cells was also excavated; these latter cells being, however, of
+smaller size than those of the limestone block, each cell being only
+six inches in depth by five inches in diameter. These cells were
+likewise fitted with double covers.
+
+On November 26th, 1825, a live toad--kept for some time previously to
+insure its being healthy--was placed in each of the twenty-four cells.
+The largest specimen weighed 1185 grains, and the smallest 115 grains.
+The stones and the immured toads were buried on the day mentioned,
+three feet deep, in Dr. Buckland's garden. There they lay until
+December 10th, 1826, when they were disinterred and their tenants
+examined. All the toads in the smaller cells of the sandstone block
+were dead, and from the progress of decomposition it was inferred that
+they had succumbed long before the date of disinterment. The majority
+of the toads in the limestone block were alive, and, curiously enough,
+one or two had actually increased in weight. Thus, No. 5, which at the
+commencement of its captivity had weighed 1185 grains, had increased
+to 1265 grains; but the glass cover of No. 5's cell was found to be
+cracked. Insects and air must therefore have obtained admittance and
+have afforded nourishment to the imprisoned toad; this supposition
+being rendered the more likely by the discovery that in one of the
+cells, the covers of which were also cracked and the tenant of which
+was dead, numerous insects were found. No. 9, weighing originally 988
+grains, had increased during its incarceration to 1116 grains; but
+No. 1, which in the year 1825 had weighed 924 grains, was found in
+December, 1826, to have decreased to 698 grains; and No. 11,
+originally weighing 936 grains, had likewise disagreed with the
+imprisonment, weighing only 652 grains when examined in 1826.
+
+At the period when the blocks of stone were thus prepared, four toads
+were pinned up in holes five inches deep and three inches in diameter,
+cut in the stem of an apple-tree; the holes being firmly plugged with
+tightly fitting wooden plugs. These four toads were found to be dead
+when examined along with the others in 1826; and of four others
+enclosed in basins made of plaster of Paris, and which were also
+buried in Dr. Buckland's garden, two were found to be dead at the end
+of a year, their comrades being alive, but looking starved and meagre.
+The toads which were found alive in the limestone block in December,
+1826, were again immured and buried, but were found to be dead,
+without leaving a single survivor, at the end of the second year of
+their imprisonment.
+
+These experiments may fairly be said to prove two points. They firstly
+show that under circumstances even of a favorable kind when compared
+with the condition popularly believed in--namely, that of being
+enclosed in a _solid_ rock--the limit of the toad's life may be
+assumed to be within two years; this period being no doubt capable of
+being extended when the animal gains a slight advantage, exemplified
+by the admission of air and insect-food. Secondly, we may reasonably
+argue that these experiments show that toads when rigorously treated,
+like other animals, become starved and meagre, and by no means
+resemble the lively, well-fed animals reported as having emerged from
+an imprisonment extending, in popular estimation, through periods of
+inconceivable duration.
+
+These tales are, in short, as devoid of actual foundation as are the
+modern beliefs in the venomous properties of the toad, or the ancient
+beliefs in the occult and mystic powers of various parts of its frame
+when used in incantations. Shakespeare, whilst attributing to the toad
+venomous qualities, has yet immortalized it in his famous simile by
+crediting it with the possession of a "precious jewel." But even in
+the latter case the animal gets but scant justice; for science strips
+it of its poetical reputation, and in this, as in other respects,
+shows it, despite fable and myth, to be zoölogically an interesting,
+but otherwise a commonplace member of the animal series.
+
+[Illustration]
+
+
+
+
+ON A PIECE OF CHALK
+
+_A LECTURE TO WORKING MEN_.
+
+(Delivered in England.)
+
+BY T.H. HUXLEY.
+
+
+[Illustration: A CHALK CLIFF.]
+
+If a well were to be sunk at our feet in the midst of the city of
+Norwich, the diggers would very soon find themselves at work in that
+white substance almost too soft to be called rock, with which we are
+all familiar as "chalk."
+
+Not only here, but over the whole county of Norfolk, the well-sinker
+might carry his shaft down many hundred feet without coming to the end
+of the chalk; and, on the sea-coast, where the waves have pared away
+the face of the land which breasts them, the scarped faces of the high
+cliffs are often wholly formed of the same material. Northward, the
+chalk may be followed as far as Yorkshire; on the south coast it
+appears abruptly in the picturesque western bays of Dorset, and breaks
+into the Needles of the Isle of Wight; while on the shores of Kent it
+supplies that long line of white cliffs to which England owes her name
+of Albion.
+
+Were the thin soil which covers it all washed away, a curved band of
+white chalk, here broader, and there narrower, might be followed
+diagonally across England from Lulworth in Dorset, to Flamborough Head
+in Yorkshire--a distance of over two hundred and eighty miles as the
+crow flies.
+
+From this band to the North Sea, on the east, and the Channel, on the
+south, the chalk is largely hidden by other deposits; but, except in
+the Weald of Kent and Sussex, it enters into the very foundation of
+all the south-eastern counties.
+
+Attaining, as it does in some places, a thickness of more than a
+thousand feet, the English chalk must be admitted to be a mass of
+considerable magnitude. Nevertheless, it covers but an insignificant
+portion of the whole area occupied by the chalk formation of the
+globe, which has precisely the same general character as ours, and is
+found in detached patches, some less, and others more extensive, than
+the English.
+
+Chalk occurs in north-west Ireland; it stretches over a large part of
+France--the chalk which underlies Paris being, in fact, a continuation
+of that of the London basin; it runs through Denmark and Central
+Europe, and extends southward to North Africa; while eastward, it
+appears in the Crimea and in Syria, and may be traced as far as the
+shores of the Sea of Aral, in Central Asia.
+
+If all the points at which true chalk occurs were circumscribed, they
+would lie within an irregular oval about three thousand miles in long
+diameter--the area of which would be as great as that of Europe, and
+would many times exceed that of the largest existing inland sea--the
+Mediterranean.
+
+Thus the chalk is no unimportant element in the masonry of the earth's
+crust, and it impresses a peculiar stamp, varying with the conditions
+to which it is exposed, on the scenery of the districts in which it
+occurs. The undulating downs and rounded coombs, covered with
+sweet-grassed turf, of our inland chalk country, have a peacefully
+domestic and mutton-suggesting prettiness, but can hardly be called
+either grand or beautiful. But on our southern coasts, the wall-sided
+cliffs, many hundred feet high, with vast needles and pinnacles
+standing out in the sea, sharp and solitary enough to serve as perches
+for the wary cormorant, confer a wonderful beauty and grandeur upon
+the chalk headlands. And in the East, chalk has its share in the
+formation of some of the most venerable of mountain ranges, such as
+the Lebanon.
+
+       *       *       *       *       *
+
+What is this wide-spread component of the surface of the earth? and
+whence did it come?
+
+You may think this no very hopeful inquiry. You may not unnaturally
+suppose that the attempt to solve such problems as these can lead to
+no result, save that of entangling the inquirer in vague speculations,
+incapable of refutation and of verification.
+
+If such were really the case, I should have selected some other
+subject than a "piece of chalk" for my discourse. But, in truth,
+after much deliberation, I have been unable to think of any topic
+which would so well enable me to lead you to see how solid is the
+foundation upon which some of the most startling conclusions of
+physical science rest.
+
+A great chapter of the history of the world is written in the chalk.
+Few passages in the history of man can be supported by such an
+overwhelming mass of direct and indirect evidence as that which
+testifies to the truth of the fragment of the history of the globe,
+which I hope to enable you to read, with your own eyes, to-night.
+
+[Illustration: MICROSCOPIC SECTION OF CHALK.
+
+(Magnified nearly 300 times.)
+
+1. Textularia. 2. Globigerina. 3. Rotalia. 4. Coccoliths.]
+
+Let me add, that few chapters of human history have a more profound
+significance for ourselves. I weigh my words well when I assert, that
+the man who should know the true history of the bit of chalk which
+every carpenter carries about in his breeches' pocket, though ignorant
+of all other history, is likely, if he will think his knowledge out to
+its ultimate results, to have a truer, and therefore a better,
+conception of this wonderful universe, and of man's relation to it,
+than the most learned student who is deep-read in the records of
+humanity and ignorant of those of nature.
+
+The language of the chalk is not hard to learn, not nearly so hard as
+Latin, if you only want to get at the broad features of the story it
+has to tell; and I propose that we now set to work to spell that story
+out together.
+
+We all know that if we "burn" chalk, the result is quicklime. Chalk,
+in fact, is a compound of carbonic acid gas and lime; and when you
+make it very hot, the carbonic acid flies away and the lime is left.
+
+By this method of procedure we see the lime, but we do not see the
+carbonic acid. If, on the other hand, you were to powder a little
+chalk and drop it into a good deal of strong vinegar, there would be a
+great bubbling and fizzing, and, finally, a clear liquid, in which no
+sign of chalk would appear. Here you see the carbonic acid in the
+bubbles; the lime, dissolved in the vinegar, vanishes from sight.
+There are a great many other ways of showing that chalk is essentially
+nothing but carbonic acid and quicklime. Chemists enunciate the result
+of all the experiments which prove this, by stating that chalk is
+almost wholly composed of "carbonate of lime."
+
+It is desirable for us to start from the knowledge of this fact,
+though it may not seem to help us very far toward what we seek. For
+carbonate of lime is a widely-spread substance, and is met with under
+very various conditions. All sorts of limestones are composed of more
+or less pure carbonate of lime. The crust which is often deposited by
+waters which have drained through limestone rocks, in the form of what
+are called stalagmites and stalactites, is carbonate of lime. Or, to
+take a more familiar example, the fur on the inside of a tea-kettle is
+carbonate of lime; and, for anything chemistry tells us to the
+contrary, the chalk might be a kind of gigantic fur upon the bottom of
+the earth-kettle, which is kept pretty hot below.
+
+Let us try another method of making the chalk tell us its own history.
+To the unassisted eye chalk looks simply like a very loose and open
+kind of stone. But it is possible to grind a slice of chalk down so
+thin that you can see through it--until it is thin enough, in fact, to
+be examined with any magnifying power that may be thought desirable. A
+thin slice of the fur of a kettle might be made in the same way. If it
+were examined microscopically, it would show itself to be a more or
+less distinctly laminated mineral substance, and nothing more.
+
+But the slice of chalk presents a totally different appearance when
+placed under the microscope. The general mass of it is made up of very
+minute granules; but, imbedded in this matrix, are innumerable bodies,
+some smaller and some larger, but, on a rough average, not more than a
+hundredth of an inch in diameter, having a well-defined shape and
+structure. A cubic inch of some specimens of chalk may contain
+hundreds of thousands of these bodies, compacted together with
+incalculable millions of the granules.
+
+[Illustration: CHALK.
+
+(Magnified nearly 100 diameters.)]
+
+The examination of a transparent slice gives a good notion of the
+manner in which the components of the chalk are arranged, and of
+their relative proportions. But, by rubbing up some chalk with a brush
+in water and then pouring off the milky fluid, so as to obtain
+sediments of different degrees of fineness, the granules and the
+minute rounded bodies may be pretty well separated from one another,
+and submitted to microscopic examination, either as opaque or as
+transparent objects. By combining the views obtained in these various
+methods, each of the rounded bodies may be proved to be a
+beautifully-constructed calcareous fabric, made up of a number of
+chambers, communicating freely with one another. The chambered bodies
+are of various forms. One of the commonest is something like a
+badly-grown raspberry, being formed of a number of nearly globular
+chambers of different sizes congregated together. It is called
+Globigerina, and some specimens of chalk consist of little else than
+Globigerinæ and granules.
+
+[Illustration: GLOBIGERINA.]
+
+Let us fix our attention upon the Globigerina. It is the spoor of the
+game we are tracking. If we can learn what it is and what are the
+conditions of its existence, we shall see our way to the origin and
+past history of the chalk.
+
+A suggestion which may naturally enough present itself is, that these
+curious bodies are the result of some process of aggregation which has
+taken place in the carbonate of lime; that, just as in winter, the
+rime on our windows simulates the most delicate and elegantly
+arborescent foliage--proving that the mere mineral matter may, under
+certain conditions, assume the outward form of organic bodies--so this
+mineral substance, carbonate of lime, hidden away in the bowels of
+the earth, has taken the shape of these chambered bodies. I am not
+raising a merely fanciful and unreal objection. Very learned men, in
+former days, have even entertained the notion that all the formed
+things found in rocks are of this nature; and if no such conception is
+at present held to be admissible, it is because long and varied
+experience has now shown that mineral matter never does assume the
+form and structure we find in fossils. If anyone were to try to
+persuade you that an oyster-shell (which is also chiefly composed of
+carbonate of lime) had crystallized out of sea-water, I suppose you
+would laugh at the absurdity. Your laughter would be justified by the
+fact that all experience tends to show that oyster-shells are formed
+by the agency of oysters, and in no other way. And if there were no
+better reasons, we should be justified, on like grounds, in believing
+that Globigerina is not the product of anything but vital activity.
+
+Happily, however, better evidence in proof of the organic nature of
+the Globigerinæ than that of analogy is forthcoming. It so happens
+that calcareous skeletons, exactly similar to the Globigerinæ of the
+chalk, are being formed, at the present moment, by minute living
+creatures, which flourish in multitudes, literally more numerous than
+the sands of the sea-shore, over a large extent of that part of the
+earth's surface which is covered by the ocean.
+
+The history of the discovery of these living Globigerinæ, and of the
+part which they play in rock-building, is singular enough. It is a
+discovery which, like others of no less scientific importance, has
+arisen, incidentally, out of work devoted to very different and
+exceedingly practical interests.
+
+When men first took to the sea, they speedily learned to look out for
+shoals and rocks; and the more the burthen of their ships increased,
+the more imperatively necessary it became for sailors to ascertain
+with precision the depth of the waters they traversed. Out of this
+necessity grew the use of the lead and sounding-line; and, ultimately,
+marine-surveying, which is the recording of the form of coasts and of
+the depth of the sea, as ascertained by the sounding-lead, upon
+charts.
+
+At the same time, it became desirable to ascertain and to indicate the
+nature of the sea-bottom, since this circumstance greatly affects its
+goodness as holding ground for anchors. Some ingenious tar, whose name
+deserves a better fate than the oblivion into which it has fallen,
+attained this object by "arming" the bottom of the lead with a lump of
+grease, to which more or less of the sand or mud, or broken shells, as
+the case might be, adhered, and was brought to the surface. But,
+however well adapted such an apparatus might be for rough nautical
+purposes, scientific accuracy could not be expected from the armed
+lead, and to remedy its defects (especially when applied to sounding
+in great depths) Lieutenant Brooke, of the American Navy, some years
+ago invented a most ingenious machine, by which a considerable portion
+of the superficial layer of the sea-bottom can be scooped out and
+brought up, from any depth to which the lead descends.
+
+In 1853, Lieutenant Brooke obtained mud from the bottom of the North
+Atlantic, between Newfoundland and the Azores, at a depth of more than
+ten thousand feet, or two miles, by the help of this sounding
+apparatus. The specimens were sent for examination to Ehrenberg of
+Berlin, and to Bailey of West Point, and those able microscopists
+found that this deep-sea mud was almost entirely composed of the
+skeletons of living organisms--the greater proportion of these being
+just like the Globigerinæ already known to occur in chalk.
+
+Thus far, the work had been carried on simply in the interests of
+science, but Lieutenant Brooke's method of sounding acquired a high
+commercial value, when the enterprise of laying down the
+telegraph-cable between this country and the United States was
+undertaken. For it became a matter of immense importance to know, not
+only the depth of the sea over the whole line, along which the cable
+was to be laid, but the exact nature of the bottom, so as to guard
+against chances of cutting or fraying the strands of that costly rope.
+The Admiralty consequently ordered Captain Dayman, an old friend and
+shipmate of mine, to ascertain the depth over the whole line of the
+cable, and to bring back specimens of the bottom. In former days, such
+a command as this might have sounded very much like one of the
+impossible things which the young prince in the Fairy Tales is ordered
+to do before he can obtain the hand of the princess. However, in the
+months of June and July, 1857, my friend performed the task assigned
+to him with great expedition and precision, without, so far as I know,
+having met with any reward of that kind. The specimens of Atlantic mud
+which he procured were sent to me to be examined and reported upon.
+
+The result of all these operations is, that we know the contours and
+the nature of the surface-soil covered by the North Atlantic, for a
+distance of seventeen hundred miles from east to west, as well as we
+know that of any part of the dry land.
+
+It is a prodigious plain--one of the widest and most even plains in
+the world. If the sea were drained off, you might drive a wagon all
+the way from Valentia, on the west coast of Ireland, to Trinity Bay in
+Newfoundland. And, except upon one sharp incline about two hundred
+miles from Valentia, I am not quite sure that it would even be
+necessary to put the skid on, so gentle are the ascents and descents
+upon that long route. From Valentia the road would lie down-hill for
+about two hundred miles to the point at which the bottom is now
+covered by seventeen hundred fathoms of sea-water. Then would come the
+central plain, more than a thousand miles wide, the inequalities of
+the surface of which would be hardly perceptible, though the depth of
+water upon it now varies from ten thousand to fifteen thousand feet;
+and there are places in which Mont Blanc might be sunk without showing
+its peak above water. Beyond this, the ascent on the American side
+commences, and gradually leads, for about three hundred miles, to the
+Newfoundland shore.
+
+Almost the whole of the bottom of this central plain (which extends
+for many hundred miles in a north and south direction) is covered by a
+fine mud, which, when brought to the surface, dries into a grayish
+white friable substance. You can write with this on a black-board, if
+you are so inclined; and, to the eye, it is quite like very soft,
+grayish chalk. Examined chemically, it proves to be composed almost
+wholly of carbonate of lime; and if you make a section of it, in the
+same way as that of the piece of chalk was made, and view it with the
+microscope, it presents innumerable Globigerinæ embedded in a granular
+matrix.
+
+Thus this deep-sea mud is substantially chalk. I say substantially,
+because there are a good many minor differences; but as these have no
+bearing on the question immediately before us--which is the nature of
+the Globigerinæ of the chalk--it is unnecessary to speak of them.
+
+Globigerinæ of every size, from the smallest to the largest, are
+associated together in the Atlantic mud, and the chambers of many are
+filled by a soft animal matter. This soft substance is, in fact, the
+remains of the creature to which the Globigerina shell, or rather
+skeleton, owes its existence--and which is an animal of the simplest
+imaginable description. It is, in fact, a mere particle of living
+jelly, without defined parts of any kind--without a mouth, nerves,
+muscles, or distinct organs, and only manifesting its vitality to
+ordinary observation by thrusting out and retracting from all parts of
+its surface long filamentous processes, which serve for arms and legs.
+Yet this amorphous particle, devoid of everything which, in the higher
+animals, we call organs, is capable of feeding, growing, and
+multiplying; of separating from the ocean the small proportion of
+carbonate of lime which is dissolved in sea-water; and of building up
+that substance into a skeleton for itself, according to a pattern
+which can be imitated by no other known agency.
+
+The notion that animals can live and flourish in the sea, at the vast
+depths from which apparently living Giobigerinæ have been brought up,
+does not agree very well with our usual conceptions respecting the
+conditions of animal life; and it is not so absolutely impossible as
+it might at first sight appear to be, that the Globigerinæ of the
+Atlantic sea-bottom do not live and die where they are found.
+
+[Illustration: DIATOM OOZE DREDGED FROM A DEPTH OF 1950 FEET.
+
+(Magnified nearly 300 diameters.)]
+
+As I have mentioned, the soundings from the great Atlantic plain are
+almost entirely made up of Globigerinæ, with the granules which have
+been mentioned, and some few other calcareous shells; but a small
+percentage of the chalky mud--perhaps at most some five per cent of
+it--is of a different nature, and consists of shells and skeletons
+composed of silex, or pure flint. These siliceous bodies belong partly
+to the lowly vegetable organisms which are called Diatomaceæ, and
+partly to the minute and extremely simple animals, termed Radiolaria.
+It is quite certain that these creatures do not live at the bottom of
+the ocean, but at its surface--where they may be obtained in
+prodigious numbers by the use of a properly constructed net. Hence it
+follows that these siliceous organisms, though they are not heavier
+than the lightest dust, must have fallen, in some cases, through
+fifteen thousand feet of water, before they reached their final
+resting-place on the ocean floor. And, considering how large a
+surface these bodies expose in proportion to their weight, it is
+probable that they occupy a great length of time in making their
+burial journey from the surface of the Atlantic to the bottom.
+
+[Illustration: RADIOLARIA. (_a._ Natural size. _b._ One-third natural
+size.)]
+
+But if the Radiolaria and Diatoms are thus rained upon the bottom of
+the sea, from the superficial layer of its waters in which they pass
+their lives, it is obviously possible that the Globigerinæ may be
+similarly derived; and if they were so, it would be much more easy to
+understand how they obtain their supply of food than it is at present.
+Nevertheless, the positive and negative evidence all points the other
+way. The skeletons of the full-grown, deep-sea Globigerinæ are so
+remarkably solid and heavy in proportion to their surface as to seem
+little fitted for floating; and, as a matter of fact, they are not to
+be found along with the Diatoms and Radiolaria, in the uppermost
+stratum of the open ocean.
+
+It has been observed, again, that the abundance of Globigerinæ, in
+proportion to other organisms of like kind, increases with the depth
+of the sea; and that deep-water Globigerinæ are larger than those
+which live in the shallower parts of the sea; and such facts negative
+the supposition that these organisms have been swept by currents from
+the shallows into the deeps of the Atlantic.
+
+It therefore seems to be hardly doubtful that these wonderful
+creatures live and die at the depths in which they are found.[1]
+
+[Footnote 1: During the cruise of H.M.S. Bull-dog, commanded by Sir
+Leopold M'Clintock, in 1860, living star-fish were brought up,
+clinging to the lowest part of the sounding-line, from a depth of 1260
+fathoms, midway between Cape Farewell, in Greenland, and the Rockall
+banks. Dr. Wallich ascertained that the sea-bottom at this point
+consisted of the ordinary Globigerina ooze, and that the stomachs of
+the star-fishes were full of Globigerinæ. This discovery removes all
+objections to the existence of living Globigerinæ at great depths,
+which are based upon the supposed difficulty of maintaining animal
+life under such conditions; and it throws the burden of proof upon
+those who object to the supposition that the Globigerinæ live and die
+where they are found.]
+
+However, the important points for us are, that the living Globigerinæ
+are exclusively marine animals, the skeletons of which abound at the
+bottom of deep seas; and that there is not a shadow of reason for
+believing that the habits of the Globigerinæ of the chalk differed
+from those of the existing species. But if this be true, there is no
+escaping the conclusion that the chalk itself is the dried mud of an
+ancient deep sea.
+
+In working over the soundings collected by Captain Dayman, I was
+surprised to find that many of what I have called the "granules" of
+that mud were not, as one might have been tempted to think at first,
+the mere powder and waste of Globigerinæ, but that they had a definite
+form and size. I termed these bodies "_coccoliths_" and doubted their
+organic nature. Dr. Wallich verified my observation, and added the
+interesting discovery that, not unfrequently, bodies similar to these
+"coccoliths" were aggregated together into spheroids, which he termed
+"_coccospheres_." So far as we knew, these bodies, the nature of which
+is extremely puzzling and problematical, were peculiar to the
+Atlantic soundings.
+
+But, a few years ago, Mr. Sorby, in making a careful examination of
+the chalk by means of thin sections and otherwise, observed, as
+Ehrenberg had done before him, that much of its granular basis
+possesses a definite form. Comparing these formed particles with those
+in the Atlantic soundings, he found the two to be identical; and thus
+proved that the chalk, like the soundings, contains these mysterious
+coccoliths and coccospheres. Here was a further and a most interesting
+confirmation, from internal evidence, of the essential identity of the
+chalk with modern deep-sea mud. Globigerinæ, coccoliths, and
+coccospheres are found as the chief constituents of both, and testify
+to the general similarity of the conditions under which both have been
+formed.[2]
+
+[Footnote 2: I have recently traced out the development of the
+"coccoliths" from a diameter of 1/7000th of an inch up to their
+largest size (which is about 1/1600th), and no longer doubt that they
+are produced by independent organisms, which, like the Globigerinæ,
+live and die at the bottom of the sea.]
+
+The evidence furnished by the hewing, facing, and superposition of the
+stones of the Pyramids, that these structures were built by men, has
+no greater weight than the evidence that the chalk was built by
+Globigerinæ; and the belief that those ancient pyramid-builders were
+terrestrial and air-breathing creatures like ourselves, is not better
+based than the conviction that the chalk-makers lived in the sea.
+
+But as our belief in the building of the Pyramids by men is not only
+grounded on the internal evidence afforded by these structures, but
+gathers strength from multitudinous collateral proofs, and is clinched
+by the total absence of any reason for a contrary belief; so the
+evidence drawn from the Globigerinæ that the chalk is an ancient
+sea-bottom, is fortified by innumerable independent lines of evidence;
+and our belief in the truth of the conclusion to which all positive
+testimony tends, receives the like negative justification from the
+fact that no other hypothesis has a shadow of foundation.
+
+It may be worth while briefly to consider a few of these collateral
+proofs that the chalk was deposited at the bottom of the sea.
+
+The great mass of the chalk is composed, as we have seen, of the
+skeletons of Globigerinæ, and other simple organisms, imbedded in
+granular matter. Here and there, however, this hardened mud of the
+ancient sea reveals the remains of higher animals which have lived and
+died, and left their hard parts in the mud, just as the oysters die
+and leave their shells behind them, in the mud of the present seas.
+
+[Illustration: UPPER SILURIAN CORALS AND CRUSTACEANS.]
+
+There are, at the present day, certain groups of animals which are
+never found in fresh waters, being unable to live anywhere but in the
+sea. Such are the corals; those corallines which are called Polyzoa;
+those creatures which fabricate the lamp-shells, and are called
+Brachiopoda; the pearly Nautilus, and all animals allied to it; and
+all the forms of sea-urchins and star-fishes.
+
+Not only are all these creatures confined to salt water at the present
+day, but, so far as our records of the past go, the conditions of
+their existence have been the same: hence, their occurrence in any
+deposit is as strong evidence as can be obtained, that that deposit
+was formed in the sea. Now the remains of animals of all the kinds
+which have been enumerated occur in the chalk, in greater or less
+abundance; while not one of those forms of shell-fish which are
+characteristic of fresh water has yet been observed in it.
+
+When we consider that the remains of more than three thousand distinct
+species of aquatic animals have been discovered among the fossils of
+the chalk, that the great majority of them are of such forms as are
+now met with only in the sea, and that there is no reason to believe
+that any one of them inhabited fresh water--the collateral evidence
+that the chalk represents an ancient sea-bottom acquires as great
+force as the proof derived from the nature of the chalk itself. I
+think you will now allow that I did not overstate my case when I
+asserted that we have as strong grounds for believing that all the
+vast area of dry land at present occupied by the chalk was once at the
+bottom of the sea, as we have for any matter of history whatever;
+while there is no justification for any other belief.
+
+[Illustration: CRETACEOUS NAUTILUS.]
+
+No less certain is it that the time during which the countries we now
+call southeast England, France, Germany, Poland, Russia, Egypt,
+Arabia, Syria, were more or less completely covered by a deep sea,
+was of considerable duration.
+
+We have already seen that the chalk is, in places, more than a
+thousand feet thick. I think you will agree with me that it must have
+taken some time for the skeletons of the animalcules of a hundredth of
+an inch in diameter to heap up such a mass as that. I have said that
+throughout the thickness of the chalk the remains of other animals are
+scattered. These remains are often in the most exquisite state of
+preservation. The valves of the shell-fishes are commonly adherent;
+the long spines of some of the sea-urchins, which would be detached by
+the smallest jar, often remain in their places. In a word, it is
+certain that these animals have lived and died when the place which
+they now occupy was the surface of as much of the chalk as had then
+been deposited; and that each has been covered up by the layer of
+Globigerina mud, upon which the creatures imbedded a little higher up
+have, in like manner, lived and died. But some of these remains prove
+the existence of reptiles of vast size in the chalk sea. These lived
+their time, and had their ancestors and descendants, which assuredly
+implies time, reptiles being of slow growth.
+
+There is more curious evidence, again, that the process of covering
+up, or, in other words, the deposit of Globigerina skeletons, did not
+go on very fast. It is demonstrable that an animal of the cretaceous
+sea might die, that its skeleton might lie uncovered upon the
+sea-bottom long enough to lose all its outward coverings and
+appendages by putrefaction; and that, after this had happened, another
+animal might attach itself to the dead and naked skeleton, might grow
+to maturity, and might itself die before the calcareous mud had buried
+the whole.
+
+Cases of this kind are admirably described by Sir Charles Lyell. He
+speaks of the frequency with which geologists find in the chalk a
+fossilized sea-urchin to which is attached the lower valve of a
+Crania. This is a kind of shell-fish, with a shell composed of two
+pieces, of which, as in the oyster, one is fixed and the other free.
+
+"The upper valve is almost invariably wanting, though occasionally
+found in a perfect state of preservation in the white chalk at some
+distance. In this case, we see clearly that the sea-urchin first lived
+from youth to age, then died and lost its spines, which were carried
+away. Then the young Crania adhered to the bared shell, grew and
+perished in its turn; after which, the upper valve was separated from
+the lower, before the Echinus became enveloped in chalky mud."
+
+A specimen in the Museum of Practical Geology, in London, still
+further prolongs the period which must have elapsed between the death
+of the sea-urchin and its burial by the Globigeringæ. For the outward
+face of the valve of a Crania, which is attached to a sea-urchin
+(Micrastor), is itself overrun by an incrusting coralline, which
+spreads thence over more or less of the surface of the sea-urchin. It
+follows that, after the upper valve of the Crania fell off, the
+surface of the attached valve must have remained exposed long enough
+to allow of the growth of the whole coralline, since corallines do not
+live imbedded in the mud.
+
+The progress of knowledge may, one day, enable us to deduce from such
+facts as these the maximum rate at which the chalk can have
+accumulated, and thus to arrive at the minimum duration of the chalk
+period. Suppose that the valve of the Crania upon which a coralline
+has fixed itself in the way just described is so attached to the
+sea-urchin that no part of it is more than an inch above the face upon
+which the sea-urchin rests. Then, as the coralline could not have
+fixed itself if the Crania had been covered up with chalk-mud, and
+could not have lived had itself been so covered, it follows, that an
+inch of chalk mud could not have accumulated within the time between
+the death and decay of the soft parts of the sea-urchin and the growth
+of the coralline to the full size which it has attained. If the decay
+of the soft parts of the sea-urchin; the attachment, growth to
+maturity, and decay of the Crania; and the subsequent attachment and
+growth of the coralline, took a year (which is a low estimate enough),
+the accumulation of the inch of chalk must have taken more than a
+year: and the deposit of a thousand feet of chalk must, consequently,
+have taken more than twelve thousand years.
+
+The foundation of all this calculation is, of course, a knowledge of
+the length of time the Crania and the coralline needed to attain their
+full size; and, on this head, precise knowledge is at present wanting.
+But there are circumstances which tend to show that nothing like an
+inch of chalk has accumulated during the life of a Crania; and, on any
+probable estimate of the length of that life, the chalk period must
+have had a much longer duration than that thus roughly assigned to
+it.
+
+Thus, not only is it certain that the chalk is the mud of an ancient
+sea-bottom; but it is no less certain that the chalk sea existed
+during an extremely long period, though we may not be prepared to give
+a precise estimate of the length of that period in years. The relative
+duration is clear, though the absolute duration may not be definable.
+The attempt to affix any precise date to the period at which the chalk
+sea began or ended its existence, is baffled by difficulties of the
+same kind. But the relative age of the cretaceous epoch may be
+determined with as great ease and certainty as the long duration of
+that epoch.
+
+You will have heard of the interesting discoveries recently made, in
+various parts of Western Europe, of flint implements, obviously worked
+into shape by human hands, under circumstances which show conclusively
+that man is a very ancient denizen of these regions.
+
+It has been proved that the old populations of Europe, whose existence
+has been revealed to us in this way, consisted of savages, such as the
+Esquimaux are now; that, in the country which is now France, they
+hunted the reindeer, and were familiar with the ways of the mammoth
+and the bison. The physical geography of France was in those days
+different from what it is now--the river Somme, for instance, having
+cut its bed a hundred feet deeper between that time and this; and it
+is probable that the climate was more like that of Canada or Siberia
+than that of Western Europe.
+
+The existence of these people is forgotten even in the traditions of
+the oldest historical nations. The name and fame of them had utterly
+vanished until a few years back; and the amount of physical change
+which has been effected since their day renders it more than probable
+that, venerable as are some of the historical nations, the workers of
+the chipped flints of Hoxne or of Amiens are to them, as they are to
+us, in point of antiquity.
+
+But, if we assign to these hoar relics of long-vanished generations of
+men the greatest age that can possibly be claimed for them, they are
+not older than the drift, or boulder clay, which, in comparison with
+the chalk, is but a very juvenile deposit. You need go no further than
+your own seaboard for evidence of this fact. At one of the most
+charming spots on the coast of Norfolk, Cromer, you will see the
+boulder clay forming a vast mass, which lies upon the chalk, and must
+consequently have come into existence after it. Huge boulders of chalk
+are, in fact, included in the clay, and have evidently been brought to
+the position they now occupy by the same agency as that which has
+planted blocks of syenite from Norway side by side with them.
+
+The chalk, then, is certainly older than the boulder clay. If you ask
+how much, I will again take you no further than the same spot upon
+your own coasts for evidence. I have spoken of the boulder clay and
+drift as resting upon the chalk. That is not strictly true. Interposed
+between the chalk and the drift is a comparatively insignificant
+layer, containing vegetable matter. But that layer tells a wonderful
+history. It is full of stumps of trees standing as they grew.
+Fir-trees are there with their cones, and hazel-bushes with their
+nuts; there stand the stools of oak and yew trees, beeches and
+alders. Hence this stratum is appropriately called the "forest-bed."
+
+It is obvious that the chalk must have been upheaved and converted
+into dry land before the timber trees could grow upon it. As the bolls
+of some of these trees are from two to three feet in diameter, it is
+no less clear that the dry land thus formed remained in the same
+condition for long ages. And not only do the remains of stately oaks
+and well-grown firs testify to the duration of this condition of
+things, but additional evidence to the same effect is afforded by the
+abundant remains of elephants, rhinoceroses, hippopotamuses, and other
+great wild beasts, which it has yielded to the zealous search of such
+men as the Rev. Mr. Gunn.
+
+When you look at such a collection as he has formed, and bethink you
+that these elephantine bones did veritably carry their owners about,
+and these great grinders crunch, in the dark woods of which the
+forest-bed is now the only trace, it is impossible not to feel that
+they are as good evidence of the lapse of time as the annual rings of
+the tree-stumps.
+
+Thus there is a writing upon the wall of cliffs at Cromer, and whoso
+runs may read it. It tells us, with an authority which cannot be
+impeached, that the ancient sea-bed of the chalk sea was raised up,
+and remained dry land, until it was covered with forest, stocked with
+the great game whose spoils have rejoiced your geologists. How long it
+remained in that condition cannot be said; but "the whirligig of time
+brought its revenges" in those days as in these. That dry land, with
+the bones and teeth of generations of long-lived elephants, hidden
+away among the gnarled roots and dry leaves of its ancient trees, sank
+gradually to the bottom of the icy sea, which covered it with huge
+masses of drift and boulder clay. Sea-beasts, such as the walrus, now
+restricted to the extreme north, paddled about where birds had
+twittered among the topmost twigs of the fir-trees. How long this
+state of things endured we know not, but at length it came to an end.
+The upheaved glacial mud hardened into the soil of modern Norfolk.
+Forests grew once more, the wolf and the beaver replaced the reindeer
+and the elephant; and at length what we call the history of England
+dawned.
+
+Thus you have, within the limits of your own county, proof that the
+chalk can justly claim a very much greater antiquity than even the
+oldest physical traces of mankind. But we may go further and
+demonstrate, by evidence of the same authority as that which testifies
+to the existence of the father of men, that the chalk is vastly older
+than Adam himself.
+
+The Book of Genesis informs us that Adam, immediately upon his
+creation, and before the appearance of Eve, was placed in the garden
+of Eden. The problem of the geographical position of Eden has greatly
+vexed the spirits of the learned in such matters, but there is one
+point respecting which, so far as I know, no commentator has ever
+raised a doubt. This is, that of the four rivers which are said to run
+out of it, Euphrates and Hiddekel are identical with the rivers now
+known by the names of Euphrates and Tigris.
+
+But the whole country in which these mighty rivers take their origin,
+and through which they run, is composed of rocks which are either of
+the same age as the chalk, or of later date. So that the chalk must
+not only have been formed, but, after its formation, the time required
+for the deposit of these later rocks, and for their upheaval into dry
+land, must have elapsed, before the smallest brook which feeds the
+swift stream of "the great river, the river of Babylon," began to
+flow.
+
+       *       *       *       *       *
+
+Thus, evidence which cannot be rebutted, and which need not be
+strengthened, though if time permitted I might indefinitely increase
+its quantity, compels you to believe that the earth, from the time of
+the chalk to the present day, has been the theatre of a series of
+changes as vast in their amount as they were slow in their progress.
+The area on which we stand has been first sea and then land, for at
+least four alternations; and has remained in each of these conditions
+for a period of great length.
+
+Nor have these wonderful metamorphoses of sea into land, and of land
+into sea, been confined to one corner of England. During the chalk
+period, or "cretaceous epoch," not one of the present great physical
+features of the globe was in existence. Our great mountain ranges,
+Pyrenees, Alps, Himalayas, Andes, have all been upheaved since the
+chalk was deposited, and the cretaceous sea flowed over the sites of
+Sinai and Ararat.
+
+All this is certain, because rocks of cretaceous or still later date
+have shared in the elevatory movements which gave rise to these
+mountain chains; and may be found perched up, in some cases, many
+thousand feet high upon their flanks. And evidence of equal cogency
+demonstrates that, though in Norfolk the forest-bed rests directly
+upon the chalk, yet it does so, not because the period at which the
+forest grew immediately followed that at which the chalk was formed,
+but because an immense lapse of time, represented elsewhere by
+thousands of feet of rock, is not indicated at Cromer.
+
+I must ask you to believe that there is no less conclusive proof that
+a still more prolonged succession of similar changes occurred before
+the chalk was deposited. Nor have we any reason to think that the
+first term in the series of these changes is known. The oldest
+sea-beds preserved to us are sands, and mud, and pebbles, the wear and
+tear of rocks which were formed in still older oceans.
+
+But, great as is the magnitude of these physical changes of the world,
+they have been accompanied by a no less striking series of
+modifications in its living inhabitants.
+
+All the great classes of animals, beasts of the field, fowls of the
+air, creeping things, and things which dwell in the waters, flourished
+upon the globe long ages before the chalk was deposited. Very few,
+however, if any, of these ancient forms of animal life were identical
+with those which now live. Certainly not one of the higher animals was
+of the same species as any of those now in existence. The beasts of
+the field, in the days before the chalk, were not our beasts of the
+field, nor the fowls of the air such as those which the eye of man has
+seen flying, unless his antiquity dates infinitely further back than
+we at present surmise. If we could be carried back into those times,
+we should be as one suddenly set down in Australia before it was
+colonized. We should see mammals, birds, reptiles, fishes, insects,
+snails, and the like, clearly recognizable as such, and yet not one of
+them would be just the same as those with which we are familiar, and
+many would be extremely different.
+
+From that time to the present, the population of the world has
+undergone slow and gradual, but incessant, changes. There has been no
+grand catastrophe--no destroyer has swept away the forms of life of
+one period, and replaced them by a totally new creation; but one
+species has vanished and another has taken its place; creatures of one
+type of structure have diminished, those of another have increased, as
+time has passed on. And thus, while the differences between the living
+creatures of the time before the chalk and those of the present day
+appear startling, if placed side by side, we are led from one to the
+other by the most gradual progress, if we follow the course of Nature
+through the whole series of those relics of her operations which she
+has left behind.
+
+[Illustration: SKELETON OF THE PTERODACTYL.]
+
+And it is by the population of the chalk sea that the ancient and the
+modern inhabitants of the world are most completely connected. The
+groups which are dying out flourish, side by side, with the groups
+which are now the dominant forms of life.
+
+Thus the chalk contains remains of those flying and swimming
+reptiles, the pterodactyl, the ichthyosaurus, and the plesiosaurus,
+which are found in no later deposits, but abounded in preceding ages.
+The chambered shells called ammonites and belemnites, which are so
+characteristic of the period preceding the cretaceous, in like manner
+die with it.
+
+[Illustration: THE SKELETON OF THE ICHTHYOSAURUS.]
+
+[Illustration: THE SKELETON OF THE PLESIOSAURUS.]
+
+[Illustration: AMMONITES.]
+
+But, among these fading remainders of a previous state of things, are
+some very modern forms of life, looking like Yankee peddlers among a
+tribe of red Indians. Crocodiles of modern type appear; bony fishes,
+many of them very similar to existing species, almost supplant the
+forms of fish which predominate in more ancient seas; and many kinds
+of living shell-fish first become known to us in the chalk. The
+vegetation acquires a modern aspect. A few living animals are not even
+distinguishable as species from those which existed at that remote
+epoch. The Globigerina of the present day, for example, is not
+different specifically from that of the chalk; and the same may be
+said of many other Foraminifera. I think it probable that critical and
+unprejudiced examination will show that more than one species of much
+higher animals have had a similar longevity; but the only example
+which I can at present give confidently is the snake's-head lamp-shell
+(_Terebratulina caput serpentis_), which lives in our English seas and
+abounded (as _Terebratulina striata_ of authors) in the chalk.
+
+[Illustration: BELEMNITES.]
+
+[Illustration: TEREBRATULINA.]
+
+The longest line of human ancestry must hide its diminished head
+before the pedigree of this insignificant shell-fish. We Englishmen
+are proud to have an ancestor who was present at the Battle of
+Hastings. The ancestors of _Terebratulina caput serpentis_ may have
+been present at a battle of Ichthyosauria in that part of the sea
+which, when the chalk was forming, flowed over the site of Hastings.
+While all around has changed, this Terebratulina has peacefully
+propagated its species from generation to generation, and stands to
+this day as a living testimony to the continuity of the present with
+the past history of the globe.
+
+       *       *       *       *       *
+
+Up to this moment I have stated, so far as I know, nothing but
+well-authenticated facts, and the immediate conclusions which they
+force upon the mind.
+
+But the mind is so constituted that it does not willingly rest in
+facts and immediate causes, but seeks always after a knowledge of the
+remoter links in the chain of causation.
+
+Taking the many changes of any given spot of the earth's surface, from
+sea to land, and from land to sea, as an established fact, we cannot
+refrain from asking ourselves how these changes have occurred. And
+when we have explained them--as they must be explained--by the
+alternate slow movements of elevation and depression which have
+affected the crusts of the earth, we go still further back, and ask,
+Why these movements?
+
+I am not certain that any one can give you a satisfactory answer to
+that question. Assuredly I cannot. All that can be said for certain
+is, that such movements are part of the ordinary course of nature,
+inasmuch as they are going on at the present time. Direct proof may be
+given, that some parts of the land of the northern hemisphere are at
+this moment insensibly rising and others insensibly sinking; and there
+is indirect but perfectly satisfactory proof, that an enormous area
+now covered by the Pacific has been deepened thousands of feet since
+the present inhabitants of that sea came into existence.
+
+Thus there is not a shadow of a reason for believing that the
+physical changes of the globe, in past times, have been effected by
+other than natural causes.
+
+Is there any more reason for believing that the concomitant
+modifications in the forms of the living inhabitants of the globe have
+been brought about in any other ways?
+
+Before attempting to answer this question, let us try to form a
+distinct mental picture of what has happened in some special case.
+
+The crocodiles are animals which, as a group, have a very vast
+antiquity. They abounded ages before the chalk was deposited; they
+throng the rivers in warm climates at the present day. There is a
+difference in the form of the joints of the backbone, and in some
+minor particulars, between the crocodiles of the present epoch and
+those which lived before the chalk; but, in the cretaceous epoch, as I
+have already mentioned, the crocodiles had assumed the modern type of
+structure. Notwithstanding this, the crocodiles of the chalk are not
+identically the same as those which lived in the times called "older
+tertiary," which succeeded the cretaceous epoch; and the crocodiles of
+the older tertiaries are not identical with those of the newer
+tertiaries, nor are these identical with existing forms. I leave open
+the question whether particular species may have lived on from epoch
+to epoch. But each epoch has had its peculiar crocodiles; though all,
+since the chalk, have belonged to the modern type, and differ simply
+in their proportions and in such structural particulars as are
+discernible only to trained eyes.
+
+How is the existence of this long succession of different species of
+crocodiles to be accounted for?
+
+Only two suppositions seem to be open to us--either each species of
+crocodile has been specially created, or it has arisen out of some
+pre-existing form by the operation of natural causes.
+
+Choose your hypothesis; I have chosen mine. I can find no warranty for
+believing in the distinct creation of a score of successive species of
+crocodiles in the course of countless ages of time. Science gives no
+countenance to such a wild fancy; nor can even the perverse ingenuity
+of a commentator pretend to discover this sense, in the simple words
+in which the writer of Genesis records the proceeding of the fifth and
+sixth days of the Creation.
+
+On the other hand, I see no good reason for doubting the necessary
+alternative, that all these varied species have been evolved from
+pre-existing crocodilian forms by the operation of causes as
+completely a part of the common order of nature as those which have
+effected the changes of the inorganic world.
+
+Few will venture to affirm that the reasoning which applies to
+crocodiles loses its force among other animals or among plants. If one
+series of species has come into existence by the operation of natural
+causes, it seems folly to deny that all may have arisen in the same
+way.
+
+       *       *       *       *       *
+
+A small beginning has led us to a great ending. If I were to put the
+bit of chalk with which we started into the hot but obscure flame of
+burning hydrogen, it would presently shine like the sun. It seems to
+me that this physical metamorphosis is no false image of what has been
+the result of our subjecting it to a jet of fervent, though nowise
+brilliant, thought to-night. It has become luminous, and its clear
+rays, penetrating the abyss of the remote past, have brought within
+our ken some stages of the evolution of the earth. And in the shifting
+"without haste, but without rest" of the land and sea, as in the
+endless variation of the forms assumed by living beings, we have
+observed nothing but the natural product of the forces originally
+possessed by the substance of the universe.
+
+[Illustration]
+
+
+
+
+A BIT OF SPONGE
+
+(Written on Scotland.)
+
+(FROM GLIMPSES OF NATURE.)
+
+BY A. WILSON.
+
+
+[Illustration]
+
+This morning, despite the promise of rain over-night, has broken with
+all the signs and symptoms of a bright July day. The Firth is bathed
+in sunlight, and the wavelets at full tide are kissing the strand,
+making a soft musical ripple as they retire, and as the pebbles run
+down the sandy slope on the retreat of the waves. Beyond the farthest
+contact of the tide is a line of seaweed dried and desiccated, mixed
+up with which, in confusing array, are masses of shells, and such
+_olla podrida_ of the sea.
+
+Tossed up at our very feet is a dried fragment of sponge, which
+doubtless the unkind waves tore from its rocky bed. It is not a large
+portion of sponge this, but its structure is nevertheless to be fairly
+made out, and some reminiscences of its history gleaned, for the sake
+of occupying the by no means "bad half-hour" before breakfast. "What
+is a sponge?" is a question which you may well ask as a necessary
+preliminary to the understanding of its personality.
+
+[Illustration: A SPONGE ATTACHED TO ITS ROCKY BED.]
+
+The questionings of childhood and the questionings of science run in
+precisely similar grooves. "What is it?" and "How does it live?" and
+"Where does it come from?" are equally the inquiries of childhood, and
+of the deepest philosophy which seeks to determine the whole history
+of life. This morning, we cannot do better than follow in the
+footsteps of the child, and to the question, "What is a sponge?" I
+fancy science will be able to return a direct answer. First of all, we
+may note that a sponge, as we know it in common life, is the horny
+skeleton or framework which was made by, and which supported, the
+living parts. These living parts consist of minute masses of that
+living jelly to which the name of _protoplasm_ has been applied. This,
+in truth, is the universal matter of life. It is the one substance
+with which life everywhere is associated, and as we see it simply in
+the sponge, so also we behold it (only in more complex guise) in the
+man. Now, the living parts of this dried cast-away sponge were found
+both in its interior and on its surface. They lined the canals that
+everywhere permeate the sponge-substance, and microscopic examination
+has told us a great deal about their nature.
+
+
+[Illustration: FIG. 1. DEVELOPMENT OF A SPONGE (_Olynthus_). 1. The
+egg. 2, 3, and 4. The process of egg-division. 5 and 6. The
+gastrula-stage. 7. The perfect sponge.]
+
+For, whether found in the canals of the sponge themselves, or embedded
+in the sponge-substance, the living sponge-particles are represented
+each by a semi-independent mass of protoplasm. So that the first view
+I would have you take of the sponge as a living mass, is, that it is a
+colony and not a single unit. It is composed, in other words, of
+aggregated masses of living particles, which bud out one from the
+other, and manufacture the supporting skeleton we know as "the sponge
+of commerce" itself. Under the microscope, these living sponge-units
+appear in various guises and shapes. Some of them are formless, and,
+as to shape, ever-altering masses, resembling that familiar animalcule
+of our pools we know as the _Amoeba_. These members of the
+sponge-colony form the bulk of the population. They are embedded in
+the sponge substance; they wander about through the meshes of the
+sponge; they seize food and flourish and grow; and they probably also
+give origin to the "eggs" from which new sponges are in due course
+produced.
+
+More characteristic however, are certain units of this living
+sponge-colony which live in the lining membrane of the canals. In
+point of fact, a sponge is a kind of Venice, a certain proportion of
+whose inhabitants, like those of the famous Queen of the Adriatic
+herself, live on the banks of the waterways. Just as in Venice we find
+the provisions for the denizens of the city brought to the inhabitants
+by the canals, so from the water, which, as we shall see, is
+perpetually circulating through a sponge, the members of the
+sponge-colony receive their food.
+
+Look, again, at the sponge-fragment which lies before us. You perceive
+half a dozen large holes or so, each opening on a little eminence, as
+it were. These apertures, bear in mind, we call _oscula_. They are the
+exits of the sponge-domain. But a close inspection of a sponge shows
+that it is riddled with finer and smaller apertures. These latter are
+the _pores_, and they form the entrances to the sponge-domain.
+
+On the banks of the canal you may see growing plentifully in summer
+time a green sponge, which is the common fresh-water species. Now, if
+you drop a living specimen of this species into a bowl of water, and
+put some powdered indigo into the water, you may note how the currents
+are perpetually being swept in by the pores and out by the oscula. In
+every living sponge this perpetual and unceasing circulation of water
+proceeds. This is the sole evidence the unassisted sight receives of
+the vitality of the sponge-colony, and the importance of this
+circulation in aiding life in these depths, to be fairly carried out
+cannot readily be over-estimated.
+
+[Illustration: WHERE SPONGES GROW.]
+
+Let us now see how this circulation is maintained. Microscopically
+regarded, we see here and there, in the sides of the sponge-passages,
+little chambers and recesses which remind one of the passing-places in
+a narrow canal. Lining these chambers, we see living sponge-units of a
+type different from the shapeless specks we noted to occur in the
+meshes of the sponge substance itself. The units of the recesses each
+consist of a living particle, whose free extremity is raised into a
+kind of collar, from which projects a lash-like filament known as a
+flagellum.
+
+This lash is in constant movement. It waves to and fro in the water,
+and the collection of lashes we see in any one chamber acts as a
+veritable brush, which by its movement not only sweeps water in by the
+pores, but sends it onwards through the sponge, and in due time sends
+it out by the bigger holes, or oscula. This constant circulation in
+the sponge discharges more than one important function. For, as
+already noted, it serves the purpose of nutrition, in that the
+particles on which sponge-life is supported are swept into the colony.
+
+Again, the fresh currents of water carry with them the oxygen gas
+which is a necessity of sponge existence, as of human life; while,
+thirdly, waste matters, inevitably alike in sponge and in man as the
+result of living, are swept out of the colony, and discharged into the
+sea beyond. Our bit of sponge has thus grown from a mere dry fragment
+into a living reality. It is a community in which already, low as it
+is, the work of life has come to be discharged by distinct and fairly
+specialized beings.
+
+The era of new sponge-life is inaugurated by means of egg-development,
+although there exists another fashion (that of gemmules or buds)
+whereby out of the parental substance young sponges are produced. A
+sponge-egg develops, as do all eggs, in a definite cycle. It undergoes
+division (Fig. 1); its one cell becomes many; and its many cells
+arrange themselves first of all into a cup-like form (5, 6 and 7),
+which may remain in this shape if the sponge is a simple one, or
+become developed into the more complex shape of the sponges we know.
+
+In every museum you may see specimens of a beautiful vase-like
+structure seemingly made of spun-glass. This is a flinty sponge, the
+"Venus flower-basket," whose presence in the sponge family redeems it
+from the charge that it contains no things of beauty whatever. So,
+too, the rocks are full of fossil-sponges, many of quaint form. Our
+piece of sponge, as we may understand, has yet other bits of history
+attached to it.... Meanwhile, think over the sponge and its ways, and
+learn from it that out of the dry things of life, science weaves many
+a fairy tale.
+
+[Illustration]
+
+
+
+
+THE GREATEST SEA-WAVE EVER KNOWN
+
+(FROM LIGHT SCIENCE IN LEISURE HOURS.)
+
+BY R.A. PROCTOR.
+
+
+[Illustration]
+
+August 13th, 1868, one of the most terrible calamities which has ever
+visited a people befell the unfortunate inhabitants of Peru. In that
+land earthquakes are nearly as common as rain storms are with us; and
+shocks by which whole cities are changed into a heap of ruins are by
+no means infrequent. Yet even in Peru, "the land of earthquakes," as
+Humboldt has termed it, no such catastrophe as that of August, 1868,
+had occurred within the memory of man. It was not one city which was
+laid in ruins, but a whole empire. Those who perished were counted by
+tens of thousands, while the property destroyed by the earthquake was
+valued at millions of pounds sterling.
+
+Although so many months have passed since this terrible calamity took
+place, scientific men have been busily engaged, until quite recently,
+in endeavoring to ascertain the real significance of the various
+events which were observed during and after the occurrence of the
+earthquake. The geographers of Germany have taken a special interest
+in interpreting the evidence afforded by this great manifestation of
+Nature's powers. Two papers have been written recently on the great
+earthquake of August 13th, 1868--one by Professor von Hochsteter, the
+other by Herr von Tschudi, which present an interesting account of the
+various effects, by land and by sea, which resulted from the
+tremendous upheaving force to which the western flanks of the Peruvian
+Andes were subjected on that day. The effects on land, although
+surprising and terrible, only differ in degree from those which have
+been observed in other earthquakes. But the progress of the great
+sea-wave which was generated by the upheaval of the Peruvian shores
+and propagated over the whole of the Pacific Ocean differs altogether
+from any earthquake phenomena before observed. Other earthquakes have
+indeed been followed by oceanic disturbances; but these have been
+accompanied by terrestrial motions, so as to suggest the idea that
+they had been caused by the motion of the sea-bottom or of the
+neighboring land. In no instance has it ever before been known that a
+well-marked wave of enormous proportions should have been propagated
+over the largest ocean tract on our globe by an earth-shock whose
+direct action was limited to a relatively small region, and that
+region not situated in the centre, but on one side of the wide area
+traversed by the wave.
+
+We propose to give a brief sketch of the history of this enormous
+sea-wave. In the first place, however, it may be well to remind the
+reader of a few of the more prominent features of the great shock to
+which this wave owed its origin.
+
+It was at Arequipa, at the foot of the lofty volcanic mountain Misti,
+that the most terrible effects of the great earthquake were
+experienced. Within historic times Misti has poured forth no lava
+streams, but that the volcano is not extinct is clearly evidenced by
+the fact that in 1542 an enormous mass of dust and ashes was vomited
+forth from its crater. On August 13th. 1868, Misti showed no signs of
+being disturbed. So far as the volcanic neighbor was concerned, the
+forty-four thousand inhabitants of Arequipa had no reason to
+anticipate the catastrophe which presently befell them. At five
+minutes past five an earthquake shock was experienced, which, though
+severe, seems to have worked little mischief. Half a minute later,
+however, a terrible noise was heard beneath the earth; a second shock
+more violent than the first was felt, and then began a swaying motion,
+gradually increasing in intensity. In the-course of the first minute
+this motion had become so violent that the inhabitants ran in terror
+out of their houses into the streets and squares. In the next two
+minutes the swaying movement had so increased that the more lightly
+built houses were cast to the ground, and the flying people could
+scarcely keep their feet. "And now," says Von Tschudi, "there followed
+during two or three minutes a terrible scene. The swaying motion which
+had hitherto prevailed changed into fierce vertical upheaval. The
+subterranean roaring increased in the most terrifying manner; then
+were heard the heart-piercing shrieks of the wretched people, the
+bursting of walls, the crashing fall of houses and churches, while
+over all rolled thick clouds of a yellowish-black dust, which, had
+they been poured forth many minutes longer, would have suffocated
+thousands." Although the shocks had lasted but a few minutes, the whole
+town was destroyed. Not one building remained uninjured, and there
+were few which did not lie in shapeless heaps of ruins.
+
+At Tacna and Arica the earth-shock was less severe, but strange and
+terrible phenomena followed it. At the former place a circumstance
+occurred the cause and nature of which yet remain a mystery. About
+three hours after the earthquake--in other words, at about eight
+o'clock in the evening--an intensely brilliant light made its
+appearance above the neighboring mountains. It lasted for fully half
+an hour, and has been ascribed to the eruption of some as yet unknown
+volcano.
+
+At Arica the sea-wave produced even more destructive effects than had
+been caused by the earthquake. About twenty minutes after the first
+earth-shock the sea was seen to retire, as if about to leave the
+shores wholly dry; but presently its waters returned with tremendous
+force. A mighty wave, whose length seemed immeasurable, was seen
+advancing like a dark wall upon the unfortunate town, a large part of
+which was overwhelmed by it. Two ships, the Peruvian corvette America,
+and the United States "double-ender" Wateree, were carried nearly half
+a mile to the north of Arica beyond the railroad which runs to Tacna,
+and there left stranded high and dry. This enormous wave was
+considered by the English vice-consul at Arica to have been fully
+fifty feet in height.
+
+At Chala three such waves swept in after the first shocks of
+earthquake. They overflowed nearly the whole of the town, the sea
+passing more than half a mile beyond its usual limits.
+
+At Islay and Iquique similar phenomena were manifested. At the former
+town the lava flowed in no less than five times, and each time with
+greater force. Afterward the motion gradually diminished, but even an
+hour and a half after the commencement of this strange disturbance the
+waves still ran forty feet above the ordinary level. At Iquique the
+people beheld the inrushing wave while it was still a great way off. A
+dark blue mass of water some fifty feet in height was seen sweeping in
+upon the town with inconceivable rapidity. An island lying before the
+harbor was completely submerged by the great wave, which still came
+rushing on black with the mud and slime it had swept from the
+sea-bottom. Those who witnessed its progress from the upper balconies
+of their houses, and presently saw its black mass rushing close
+beneath their feet, looked on their safety as a miracle. Many
+buildings were indeed washed away, and in the low-lying parts of the
+town there was a terrible loss of life. After passing far inland, the
+wave slowly returned sea-ward, and, strangely enough, the sea, which
+elsewhere heaved and tossed for hours after the first great wave had
+swept over it, here came soon to rest.
+
+At Callao a yet more singular instance was afforded of the effect
+which circumstances may have upon the motion of the sea after a great
+earthquake has disturbed it. In former earthquakes Callao has suffered
+terribly from the effects of the great sea-wave. In fact, on two
+occasions the whole town has been destroyed, and nearly all its
+inhabitants have been drowned, through the inrush of precisely such
+waves as flowed into the ports of Arica and Chala. But upon this
+occasion the centre of subterranean disturbance must have been so
+situated that either the wave was diverted from Callao, or, more
+probably, two waves reached Callao from different sources and at
+different times, so that the two undulations partly counteracted each
+other. Certain it is that, although the water retreated strangely from
+the coast near Callao, insomuch that a wide tract of the sea-bottom
+was uncovered, there was no inrushing wave comparable with those
+described above. The sea afterward rose and fell in an irregular
+manner, a circumstance confirming the supposition that the disturbance
+was caused by two distinct oscillations. Six hours after the
+occurrence of the earth-shock the double oscillations seemed for a
+while to have worked themselves into unison, for at this time three
+considerable waves rolled in upon the town. But clearly these waves
+must not be compared with those which in other instances had made
+their appearance within half an hour of the earth-throes. There is
+little reason to doubt that if the separate oscillations had
+re-enforced each other earlier, Callao would have been completely
+destroyed. As it was, a considerable amount of mischief was effected;
+but the motion of the sea presently became irregular again, and so
+continued until the morning of August 14th, when it began to ebb with
+some regularity. But during the 14th there were occasional renewals of
+the irregular motion, and several days elapsed before the regular ebb
+and flow of the sea were resumed.
+
+Such were among the phenomena presented in the region where the
+earthquake itself was felt. It will be seen at once that within this
+region, or rather along that portion of the sea-coast which falls
+within the central region of disturbance, the true character of the
+sea-wave generated by the earthquake could not be recognized. If a
+rock fall from a lofty cliff into a comparatively shallow sea, the
+water around the place where the rock has fallen is disturbed in an
+irregular manner. The sea seems at one place to leap up and down;
+elsewhere one wave seems to beat against another, and the sharpest eye
+can detect no law in the motion of the seething waters. But presently,
+outside the scene of disturbance, a circular wave is seen to form, and
+if the motion of this wave be watched it is seen to present the most
+striking contrast with the turmoil and confusion at its centre. It
+sweeps onward and outward in a regular undulation. Gradually it loses
+its circular figure (unless the sea-bottom happens to be unusually
+level), showing that although its motion is everywhere regular, it is
+not everywhere equally swift. A wave of this sort, though incomparably
+vaster, swept swiftly away on every side from the scene of the great
+earthquake near the Peruvian Andes. It has been calculated that the
+width of this wave varied from one million to five million feet, or,
+roughly, from two hundred to one thousand miles, while, when in
+mid-Pacific, the length of the wave, measured along its summit in a
+widely-curved path from one side to another of the great ocean,
+cannot have been less than eight thousand miles.
+
+[Illustration: OVER A LARGE PORTION OF ITS COURSE ITS PASSAGE WAS
+UNNOTED.]
+
+We cannot tell how deep-seated was the centre of subterranean action;
+but there can be no doubt it was very deep indeed, because otherwise
+the shock felt in towns separated from each other by hundreds of miles
+could not have been so nearly contemporaneous. Therefore the portion
+of the earth's crust upheaved must have been enormous, for the length
+of the region where the direct effects of the earthquake were
+perceived is estimated by Professor von Hochsteter at no less than
+two hundred and forty miles. The breadth of the region is unknown,
+because the slope of the Andes on one side and the ocean on the other
+concealed the motion of the earth's crust.
+
+The great ocean-wave swept, as we have said, in all directions around
+the scene of the earth-throe. Over a large part of its course its
+passage was unnoted, because in the open sea the effects even of so
+vast an undulation could not be perceived. A ship would slowly rise as
+the crest of the great wave passed under her, and then as slowly sink
+again. This may seem strange, at first sight, when it is remembered
+that in reality the great sea-wave we are considering swept at the
+rate of three or four hundred sea-miles an hour over the larger part
+of the Pacific. But when the true character of ocean-waves is
+understood, when it is remembered that there is no transference of the
+water itself at this enormous rate, but simply a transmission of
+motion (precisely as when in a high wind waves sweep rapidly over a
+cornfield, while yet each cornstalk remains fixed in the ground), it
+will be seen that the effects of the great sea-wave could only be
+perceived near the shore. Even there, as we shall presently see, there
+was much to convey the impression that the land itself was rising and
+falling rather than that the deep was moved. But among the hundreds of
+ships which were sailing upon the Pacific when its length and breadth
+were traversed by the great sea-wave, there was not one in which any
+unusual motion was perceived.
+
+In somewhat less than three hours after the occurrence of the
+earthquake the ocean-wave inundated the port of Coquimbo, on the
+Chilean seaboard, some eight hundred miles from Arica. An hour or so
+later it had reached Constitucion, four hundred and fifty miles
+farther south; and here for some three hours the sea rose and fell
+with strange violence. Farther south, along the shore of Chile, even
+to the island of Chiloe, the shore-wave travelled, though with
+continually diminishing force, owing, doubtless, to the resistance
+which the irregularities of the shore opposed to its progress.
+
+The northerly shore-wave seems to have been more considerable; and a
+moment's study of a chart of the two Americas will show that this
+circumstance is highly significant. When we remember that the
+principal effects of the land-shock were experienced within that angle
+which the Peruvian Andes form with the long north-and-south line of
+the Chilean and Bolivian Andes, we see at once that, had the centre of
+the subterranean action been near the scene where the most destructive
+effects were perceived, no sea-wave, or but a small one, could have
+been sent toward the shores of North America. The projecting shores of
+northern Peru and Ecuador could not have failed to divert the sea-wave
+toward the west; and though a reflected wave might have reached
+California, it would only have been after a considerable interval of
+time, and with dimensions much less than those of the sea-wave which
+travelled southward. When we see that, on the contrary, a wave of even
+greater proportions travelled toward the shores of North America, we
+seem forced to the conclusion that the centre of the subterranean
+action must have been so far to the west that the sea-wave generated
+by it had a free course to the shores of California.
+
+Be this as it may, there can be no doubt that the wave which swept the
+shores of Southern California, rising upward of sixty feet above the
+ordinary sea-level, was absolutely the most imposing of all the
+indirect effects of the great earthquake. When we consider that even
+in San Pedro Bay, fully five thousand miles from the centre of
+disturbance, a wave twice the height of an ordinary house rolled in
+with unspeakable violence only a few hours after the occurrence of the
+earth-throe, we are most strikingly impressed with the tremendous
+energy of the earth's movement.
+
+Turning to the open ocean, let us track the great wave on its course
+past the multitudinous islands which dot the surface of the Pacific.
+
+The inhabitants of the Sandwich Islands, which lie about six thousand
+three hundred miles from Arica, might have imagined themselves safe
+from any effects which could be produced by an earthquake taking place
+so far away from them. But on the night between August 13th and 14th,
+the sea around this island group rose in a surprising manner, insomuch
+that many thought the islands were sinking, and would shortly subside
+altogether beneath the waves. Some of the smaller islands, indeed,
+were for a time completely submerged. Before long, however, the sea
+fell again, and as it did so the observers "found it impossible to
+resist the impression that the islands were rising bodily out of the
+water." For no less than three days this strange oscillation of the
+sea continued to be experienced, the most remarkable ebbs and floods
+being noticed at Honolulu, on the island of Woahoo.
+
+But the sea-wave swept onward far beyond these islands.
+
+At Yokohama, in Japan, more than ten thousand five hundred miles from
+Arica, an enormous wave poured in on August 14th, but at what hour we
+have no satisfactory record. So far as distance is concerned, this
+wave affords most surprising evidence of the stupendous nature of the
+disturbance to which the waters of the Pacific Ocean had been
+subjected. The whole circumference of the earth is but twenty-five
+thousand miles, so that this wave had travelled over a distance
+considerably greater than two-fifths of the earth's circumference. A
+distance which the swiftest of our ships could not traverse in less
+than six or seven weeks had been swept over by this enormous
+undulation in the course of a few hours.
+
+More complete details reach us from the Southern Pacific.
+
+Shortly before midnight the Marquesas Isles and the low-lying Tuamotu
+group were visited by the great wave, and some of these islands were
+completely submerged by it. The lonely Opara Isle, where the steamers
+which run between Panama and New Zealand have their coaling station,
+was visited at about half-past eleven in the evening by a billow which
+swept away a portion of the coal depot. Afterward great waves came
+rolling in at intervals of about twenty minutes, and several days
+elapsed before the sea resumed its ordinary ebb and flow.
+
+It was not until about half-past two on the morning of August 14th
+that the Samoa Isles (sometimes called the Navigator Islands) were
+visited by the great wave. The watchmen startled the inhabitants from
+their sleep by the cry that the sea was about to overwhelm them; and
+already, when the terrified people rushed from their houses, the sea
+was found to have risen far above the highest water-mark. But it
+presently began to sink again, and then commenced a series of
+oscillations, which lasted for several days, and were of a very
+remarkable nature. Once in every quarter of an hour the sea rose and
+fell, but it was noticed that it rose twice as rapidly as it sank.
+This peculiarity is well worth remarking. The eminent physicist Mallet
+speaks thus (we follow Lyell's quotation) about the waves which
+traverse an open sea: "The great sea-wave, advancing at the rate of
+several miles in a minute, consists, in the deep ocean, of a long, low
+swell of enormous volume, having an equal slope before and behind, and
+that so gentle that it might pass under a ship without being noticed.
+But when it reaches the edge of soundings, its front slope becomes
+short and steep, while its rear slope is long and gentle." On the
+shores visited by such a wave, the sea would appear to rise more
+rapidly than it sank. We have seen that this happened on the shores of
+the Samoa group, and therefore the way in which the sea rose and fell
+on the days following the great earthquake gave significant evidence
+of the nature of the sea-bottom in the neighborhood of these islands.
+As the change of the great wave's figure could not have been quickly
+communicated, we may conclude with certainty that the Samoan Islands
+are the summits of lofty mountains, whose sloping sides extend far
+toward the east.
+
+This conclusion affords interesting evidence of the necessity of
+observing even the seemingly trifling details of important phenomena.
+
+The wave which visited the New Zealand Isles was altogether different
+in character, affording a noteworthy illustration of another remark of
+Mallet's. He says that where the sea-bottom slopes in such a way that
+there is water of some depth close inshore, the great wave may roll in
+and do little damage; and we have seen that so it happened in the case
+of the Samoan Islands. But he adds that, "where the shore is shelving
+there will be first a retreat of the water, and then the wave will
+break upon the beach and roll far in upon the land." This is precisely
+what happened when the great wave reached the eastern shores of New
+Zealand, which are known to shelve down to very shallow water,
+continuing far away to sea toward the east.
+
+At about half-past three on the morning of August 14th the water began
+to retreat in a singular manner from the port of Littleton, on the
+eastern shores of the southernmost of the New Zealand Islands. At
+length the whole port was left entirely dry, and so remained for about
+twenty minutes. Then the water was seen returning like a wall of foam
+ten or twelve feet in height, which rushed with a tremendous noise
+upon the port and town. Toward five o'clock the water again retired,
+very slowly as before, not reaching its lowest ebb until six. An hour
+later a second huge wave inundated the port. Four times the sea
+retired and returned with great power at intervals of about two hours.
+Afterward the oscillation of the water was less considerable, but it
+had not wholly ceased until August 17th, and only on the 18th did the
+regular ebb and flow of the tide recommence.
+
+Around the Samoa group the water rose and fell once in every fifteen
+minutes, while on the shores of New Zealand each oscillation lasted no
+less than two hours. Doubtless the different depths of water, the
+irregular conformation of the island groups, and other like
+circumstances, were principally concerned in producing these singular
+variations. Yet they do not seem fully sufficient to account for so
+wide a range of difference. Possibly a cause yet unnoticed may have
+had something to do with the peculiarity. In waves of such enormous
+extent it would be quite impossible to determine whether the course of
+the wave motion was directed full upon a line of shore or more or less
+obliquely. It is clear that in the former case the waves would seem to
+follow each other more swiftly than in the latter, even though there
+were no difference in their velocity.
+
+Far on beyond the shores of New Zealand the great wave coursed,
+reaching at length the coast of Australia. At dawn of August 14th
+Moreton Bay was visited by five well-marked waves. At Newcastle, on
+the Hunter River, the sea rose and fell several times in a remarkable
+manner, the oscillatory motion commencing at half-past six in the
+morning. But the most significant evidence of the extent to which the
+sea-wave travelled in this direction was afforded at Port Fairy,
+Belfast, South Victoria. Here the oscillation of the water was
+distinctly perceived at midday on August 14th; and yet, to reach this
+point, the sea-wave must not only have travelled on a circuitous
+course nearly equal in length to half the circumference of the earth,
+but must have passed through Bass's Straits, between Australia and Van
+Diemen's Land, and so have lost a considerable portion of its force
+and dimensions. When we remember that had not the effects of the
+earth-shock on the water been limited by the shores of South America,
+a wave of disturbance equal in extent to that which travelled westward
+would have swept toward the east, we see that the force of the shock
+was sufficient to have disturbed the waters of an ocean covering the
+whole surface of the earth. For the sea-waves which reached Yokohama
+in one direction and Port Fairy in another had each traversed a
+distance nearly equal to half the earth's circumference; so that if
+the surface of the earth were all sea, waves setting out in opposite
+directions from the centre of disturbance would have met each other at
+the antipodes of their starting-point.
+
+It is impossible to contemplate the effects which followed the great
+earthquake--the passage of a sea-wave of enormous volume over fully
+one third of the earth's surface, and the force with which, on the
+farthermost limits of its range, the wave rolled in upon shores more
+than ten thousand miles from its starting-place--without feeling that
+those geologists are right who deny that the subterranean forces of
+the earth are diminishing in intensity. It may be difficult, perhaps,
+to look on the effects which are ascribed to ancient earth-throes
+without imagining for a while that the power of modern earthquakes is
+altogether less. But when we consider fairly the share which time had
+in those ancient processes of change, when we see that while mountain
+ranges were being upheaved or valleys depressed to their present
+position, race after race, and type after type appeared on the earth,
+and lived out the long lives which belong to races and to types, we
+are recalled to the remembrance of the great work which the earth's
+subterranean forces are still engaged upon. Even now continents are
+being slowly depressed or upheaved; even now mountain ranges are being
+raised to a new level, tablelands are in process of formation, and
+great valleys are being gradually scooped out. It may need an
+occasional outburst, such as the earthquake of August, 1868, to remind
+us that great forces are at work beneath the earth's surface. But, in
+reality, the signs of change have long been noted. Old shore-lines
+shift their place, old soundings vary; the sea advances in one place
+and retires in another; on every side Nature's plastic hand is at work
+modelling and remodelling the earth, in order that it may always be a
+fit abode for those who are to dwell upon it.
+
+[Illustration]
+
+
+
+
+THE PHOSPHORESCENT SEA
+
+(FROM STUDIES OF ANIMATED NATURE.)
+
+BY W.S. DALLAS.
+
+
+[Illustration]
+
+It is not merely on land that this phenomenon of phosphorescence is to
+be seen in living forms. Among marine animals, indeed, it is a
+phenomenon much more general, much more splendid, and, we may add,
+much more familiar to those who live on our coasts. There must be many
+in the British Isles who have never had the opportunity of seeing the
+light of the glow-worm, but there can be few of those who have
+frequented in summer any part of our coasts, who have never seen that
+beautiful greenish light which is then so often visible, especially on
+our southern shores, when the water is disturbed by the blade of an
+oar or the prow of a boat or ship. In some cases, even on our own
+shores, the phenomenon is much more brilliant, every rippling wave
+being crested with a line of the same peculiar light, and in warmer
+seas exhibitions of this kind are much more common. It is now known
+that this light is due to a minute living form, to which we will
+afterward return.
+
+But before going on to speak in some detail of the organisms to which
+the phosphorescence of the sea is due, it will be as well to mention
+that the kind of phosphorescence just spoken of is only one mode in
+which the phenomenon is exhibited on the ocean. Though sometimes the
+light is shown in continuous lines whenever the surface is disturbed,
+at other times, and, according to M. de Quatrefages, more commonly,
+the light appears only in minute sparks, which, however numerous,
+never coalesce. "In the little channel known as the Sund de Chausez,"
+he writes, "I have seen on a dark night each stroke of the oar kindle,
+as it were, myriads of stars, and the wake of the craft appeared in a
+manner besprinkled with diamonds." When such is the case the
+phosphorescence is due to various minute animals, especially
+crustaceans; that is, creatures which, microscopically small as they
+are, are yet constructed more or less on the type of the lobster or
+cray-fish.
+
+At other times, again, the phosphorescence is still more partial.
+"Great domes of pale gold with long streamers," to use the eloquent
+words of Professor Martin Duncan, "move slowly along in endless
+succession; small silvery disks swim, now enlarging and now
+contracting, and here and there a green or bluish gleam marks the
+course of a tiny, but rapidly rising and sinking globe. Hour after
+hour the procession passes by, and the fishermen hauling in their nets
+from the midst drag out liquid light, and the soft sea jellies,
+crushed and torn piecemeal, shine in every clinging particle. The
+night grows dark, the wind rises and is cold, and the tide changes; so
+does the luminosity of the sea. The pale spectres below the surface
+sink deeper, and are lost to sight, but the increasing waves are
+tinged here and there with green and white, and often along a line,
+where the fresh water is mixing with the salt in an estuary, there is
+a brightness so intense that boats and shores are visible.... But if
+such sights are to be seen on the surface, what must not be the
+phosphorescence of the depths! Every sea-pen is glorious in its light,
+in fact, nearly every eight-armed Alcyonarian is thus resplendent, and
+the social Pyrosoma, bulky and a free swimmer, glows like a bar of hot
+metal with a white and green radiance."
+
+Such accounts are enough to indicate how varied and how general a
+phenomenon is the phosphorescence of the sea. To take notice of one
+tithe of the points of interest summed up in the paragraph just quoted
+would occupy many pages, and we must therefore confine the attention
+to a few of the most interesting facts relating to marine
+phosphorescence.
+
+We will return to that form of marine luminosity to which we first
+referred: what is known as the general or diffused phosphorescence of
+the sea. From this mode of describing it the reader must not infer
+that the surface of the ocean is ever to be seen all aglow in one
+sheet of continuous light. So far, at least, as was ever observed by
+M. de Quatrefages, who studied this phenomenon carefully and during
+long periods on the coasts of Brittany and elsewhere, no light was
+visible when the surface of the sea was perfectly still. On the other
+hand, when the sea exhibits in a high degree the phenomenon of
+diffused phosphorescence no disturbance can be too slight to cause the
+water to shine with that peculiar characteristic gleam. Drop but a
+grain of sand upon its surface, and you will see a point of light
+marking the spot where it falls, and from that point as a centre a
+number of increasing wavelets, each clearly defined by a line of
+light, will spread out in circles all around.
+
+The cause of this diffused phosphorescence was long the subject of
+curiosity, and was long unknown, but more than a hundred years ago (in
+1764) the light was stated by M. Kigaut to proceed from a minute and
+very lowly organism, now known as _Noctiluca miliaris_; and subsequent
+researches have confirmed this opinion. This Noctiluca is a spherical
+form of not more than one-fiftieth of an inch in size, with a slight
+depression or indentation at one point, marking the position of a
+mouth leading to a short digestive cavity, and having close beside it
+a filament, by means of which it probably moves about. The sphere is
+filled with protoplasm, in which there is a nucleus and one or more
+gaps, or "vacuoles." Such is nearly all the structure that can be
+discerned with the aid of the microscope in this simple organism.
+
+Nevertheless, this lowly form is the chief cause of that diffused
+phosphorescence which is sometimes seen over a wide extent of the
+ocean. How innumerable the individuals belonging to this species must
+therefore be, may be left to the imagination. Probably the Noctiluca
+is not rivalled in this respect even by miscroscopic unicellular algæ
+which compose the "red snow."
+
+By filtering sea-water containing Noctilucæ its light can be
+concentrated, and it has been found that a few teaspoonfuls will then
+yield light enough to enable one to read holding a book at the
+ordinary distance from the eyes--about ten inches.
+
+A singular and highly remarkable case of diffused marine
+phosphorescence was observed by Nordenskiöld during his voyage to
+Greenland in 1883. One dark night, when the weather was calm and the
+sea smooth, his vessel was steaming across a narrow inlet called the
+Igaliko Fjord, when the sea was suddenly observed to be illumined in
+the rear of the vessel by a broad but sharply-defined band of light,
+which had a uniform, somewhat golden sheen, quite unlike the ordinary
+bluish-green phosphorescence of the sea. The latter kind of light was
+distinctly visible at the same time in the wake of the vessel. Though
+the steamer was going at the rate of from five to six miles an hour,
+the remarkable sheet of light got nearer and nearer. When quite close,
+it appeared as if the vessel were sailing in a sea of fire or molten
+metal. In the course of an hour the light passed on ahead, and
+ultimately it disappeared in the remote horizon. The nature of this
+phenomenon Nordenskiöld is unable to explain; and unfortunately he had
+not the opportunity of examining it with the spectroscope.
+
+If we come now to consider the more partial phosphorescence of the
+sea, we find that it is due to animals belonging to almost every group
+of marine forms--to Echinoderms, or creatures of the sea-urchin and
+star-fish type, to Annelid worm, to Medusidæ, or jelly-fish, as they
+are popularly called, including the "great domes" and the "silvery
+disks" of the passage above quoted from Professor Martin Duncan, to
+Tunicates, among which is the Pyrosoma, to Mollusks, Crustaceans, and
+in very many cases to Actinozoa, or forms belonging to the type of the
+sea anemone and the coral polyp.
+
+Of these we will single out only a few for more special notice.
+
+Many of the Medusidæ, or jelly-fish, possess the character of which we
+are speaking. In some cases the phosphorescence is spontaneous among
+them, but in others it is not so; the creature requires to be
+irritated or stimulated in some way before it will emit the light. It
+is spontaneous, for example, in the _Pelagia phosphorea_, but not in
+the allied _Pelagia noctiluca_, a very common form in the
+Mediterranean.
+
+In both of the jelly-fishes just mentioned the phosphorescence, when
+displayed at all, is on the surface of the swimming disk, and this is
+most commonly the case with the whole group. Sometimes, however, the
+phosphorescence is specially localized. In some forms, as in
+_Thaumantius pilosella_ and other members of the same genus, it is
+seen in buds at the base of tentacles given off from the margin of the
+swimming-bell. In other cases it is situated in certain internal
+organs, as in the canals which radiate from the centre to the margin
+of the bell, or in the ovaries. It is from this latter seat that the
+phosphorescence proceeds in _Oceania pilata_, the form which gives out
+such a light that Ehrenberg compared it to a lamp-globe lighted by a
+flame.
+
+The property of emitting a phosphorescent light, sometimes
+spontaneously and sometimes on being stimulated, is likewise
+exemplified in the Ctenophora, a group resembling the Medusidæ in
+the jelly-like character of their bodies, but more closely allied in
+structure to the Actinozoa. But we will pass over these cases in order
+to dwell more particularly on the remarkable tunicate known as
+Pyrosoma, a name indicative of its phosphorescent property, being
+derived from two Greek words signifying fire-body. As shown in the
+illustration Pyrosoma is not a single creature, but is composed of a
+whole colony of individuals, each of which is represented by one of
+the projections on the surface of the tube, closed at one end, which
+they all combine to form. The free end on the exterior contains the
+mouth, while there is another opening in each individual toward the
+interior of the tube. Such colonies, which swim about by the alternate
+contraction and dilatation of the individuals composing them, are
+pretty common in the Mediterranean, where they may attain the length
+of perhaps fourteen inches, with a breadth of about three inches. In
+the ocean they may reach a much greater size. Mr. Moseley, in his
+"Notes of a Naturalist on the Challenger," mentions a giant specimen
+which he once caught in the deep-sea trawl, a specimen four feet in
+length and ten inches in diameter, with "walls of jelly about an inch
+in thickness."
+
+[Illustration: A. PYROSOMA. B. PONITON. (Magnified.)]
+
+The same naturalist states that the light emitted by this compound
+form is the most beautiful of all kinds of phosphorescence. When
+stimulated by a touch, or shake, or swirl of the water, it "gives out
+a globe of bluish light, which lasts for several seconds, as the
+animal drifts past several feet beneath the surface, and then suddenly
+goes out." He adds that on the giant specimen just referred to be
+wrote his name with his finger as it lay on the deck in a tub at
+night, and in a few seconds he had the gratification of seeing his
+name come out in "letters of fire."
+
+Among mollusks, the best known instance of phosphorescence is in the
+rock-boring Pholas, the luminosity of which after death is mentioned
+by Pliny. But it is not merely after death that Pholas becomes
+luminous--a phenomenon perfectly familiar even in the case of many
+fish, especially the herring and mackerel. It was long before the
+luminosity of the living animal was known, but this is now a
+well-ascertained fact; and Panceri, an Italian naturalist, recently
+dead, has been able to discover in this, as in several other marine
+phosphorescent forms, the precise seat of the light-giving bodies,
+which he has dissected out again and again for the sake of making
+experiments in connection with this subject.
+
+A more beautiful example of a phosphorescent mollusk is presented by a
+sea-slug called _Phyllirhoë bucephala_. This is a creature of from one
+and a half to two inches in length, without a shell in the adult
+stage, and without even gills. It breathes only by the general surface
+of the body. It is common enough in the Mediterranean, but is not easy
+to see, as it is almost perfectly transparent, so that it cannot be
+distinguished without difficulty, by day at least, from the medium in
+which it swims. By night, however, it is more easily discerned, in
+consequence of its property of emitting light. When disturbed or
+stimulated in any way, it exhibits a number of luminous spots of
+different sizes irregularly distributed all over it, but most thickly
+aggregated on the upper and under parts. These phosphorescent spots,
+it is found, are not on the surface, but for the most part represent
+so many large cells which form the terminations of nerves, and are
+situated underneath the transparent cuticle. The spots shine with
+exceptional brilliancy when the animal is withdrawn from the water and
+stimulated by a drop of ammonia.
+
+Among the Annelid worms a species of _Nereis_, or sea-centipedes, has
+earned by its phosphorescent property the specific name of _noctiluca_
+(night-shining), and the same property is very beautifully shown in
+_Polynoë_, a near ally of the familiar sea-mouse. M. de Quatrefages
+speaks with enthusiasm of the beauty of the spectacle presented by
+this latter form when examined under a microscope magnifying to the
+extent of a hundred diameters. He then found, as he did in the great
+majority of cases which he studied, that the phosphorescence was
+confined to the motor muscles, and was manifested solely when these
+were in the act of contracting, manifested, too, not in continuous
+lines along the course of the muscles, but in rows of brilliant
+points.
+
+More interesting than the Annelids, however, are the Alcyonarian
+Actinozoa. The Actinozoa have already been described as formed on the
+type of the sea-anemone and the coral polyp, that is, they are all
+animals with a radiate structure, attached to one end, and having
+their only opening at the other end, which is surrounded by tentacles.
+In the Alcyonarian forms belonging to this great group these tentacles
+are always eight in number, and fringed on both sides. Moreover, these
+forms are almost without exception compound. Like the Pyrosoma, they
+have a common life belonging to a whole stock or colony, as well as an
+individual life.
+
+Now, throughout this sub-division of the Actinozoa phosphorescence is
+a very general phenomenon. Professor Moseley, already quoted as a
+naturalist accompanying the Challenger expedition, informs us that
+"all the Alcyonarians dredged by the Challenger in deep water were
+found to be brilliantly phosphorescent when brought to the surface."
+
+Among these Alcyonarians are the sea-pens mentioned in the quotation
+above made from Professor Martin Duncan. Each sea-pen is a colony of
+Alcyonarians, and the name is due to the singular arrangement of the
+individuals upon the common stem. This stem is supported internally by
+a coral rod, but its outer part is composed of fleshy matter belonging
+to the whole colony. The lower portion of it is fixed in the muddy
+bottom of the sea, but the upper portion is free, and gives off a
+number of branches, on which the individual polyps are seated. The
+whole colony thus has the appearance of a highly ornamental pen.
+
+There is one British species, _Pennatula phosphorea_, which is found
+in tolerably deep water, and is from two to four inches in length. The
+specific name again indicates the phosphorescent quality belonging to
+it. When irritated, it shines brilliantly, and the curious thing is
+that the phosphorescence travels gradually on from polyp to polyp,
+starting from the point at which the irritation is applied. If the
+lower part of the stem is irritated, the phosphorescence passes
+gradually upwards along each pair of branches in succession; but if
+the top is irritated the phosphorescence will pass in the same way
+downwards. When both top and bottom are irritated simultaneously two
+luminous currents start at once, and, meeting in the middle, usually
+become extinguished there; but on one occasion Panceri found that the
+two crossed, and each completed its course independently of the other.
+Those of our readers who have had opportunities of making or seeing
+experiments with the sensitive plant (_Mimosa pudica_) will be
+reminded of the way in which, when that plant is irritated, the
+influence travels regularly on from pinnules to pinnules and pinnae to
+pinnae.
+
+In all the cases mentioned the phenomenon of phosphorescence is
+exhibited by invertebrate animals; but though rare, it is not an
+unknown phenomenon even in living vertebrates. In a genus of deep-sea
+fishes called Stomias, Gunther mentions that a "series of
+phosphorescent dots run along the lower side of the head, body, and
+tail." Several other deep-sea fishes, locally phosphorescent, seem to
+have been dredged up by the French ship Talisman in its exploring
+cruise off the west coast of Northern Africa in 1883. During the same
+expedition, a number of deep-sea phosphorescent crustaceans were
+dredged up, the phosphorescence being in some cases diffused over the
+whole body, in other cases localized to particular areas. In deep-sea
+forms the phenomenon is, in fact, so common, as to have given rise to
+the theory that in the depths of the ocean, where the light of the
+sun cannot penetrate, the phosphorescence of various organisms diffuse
+a light which limits the domain of absolute darkness.
+
+So much by way of illustration regarding the phosphorescence exhibited
+by animals, terrestrial and marine; but it ought to be noticed that
+there are also a few cases in which the same phenomenon is to be
+witnessed in plants. These are not so numerous as was at one time
+supposed, the property having been mistakenly ascribed to some plants
+not really luminous.
+
+[Illustration: A PHOSPHORESCENT SEA.]
+
+In some instances the mistake appears to have been due to a subjective
+effect produced by brilliantly colored (red or orange) flowers, such
+as the great Indian cress, the orange lily, the sunflower, and the
+marigold. The fact that such flowers do give out in the dusk sudden
+flashes of light has often been stated on the authority of a daughter
+of Linnæus, subsequently backed by the assertions of various other
+observers. But most careful observers seem to be agreed that the
+supposed flashes of light are in reality nothing else than a certain
+dazzling of the eyes.
+
+In another case, in which a moss, _Schistostega osmundacea_, has been
+stated to be phosphorescent, the effect is said to be really due to
+the refraction and reflection of light by minute crystals scattered
+over its highly cellular leaves, and not to be produced at all where
+the darkness is complete.
+
+Among plants, genuine phosphorescence is to be found chiefly in
+certain fungi, the most remarkable of which is _Rhizomorpha
+subterranea_, which is sometimes to be seen ramifying over the walls
+of dark, damp mines, caverns, or decayed towers, and emitting at
+numerous points a mild phosphorescent light, which is sometimes bright
+enough to allow of surrounding objects being distinguished by it. The
+name of "vegetable glow-worm" has sometimes been applied to this
+curious growth.
+
+Among other phosphorescent fungi are several species of Agaricus,
+including the _A. olearius_ of Europe, _A. Gardneri_ of Brazil, and
+_A. lampas_ of Australia, and besides the members of this genus,
+_Thelaphora cærulea_, which is the cause of the phosphorescent light
+sometimes to be seen on decaying wood--the "touchwood" which many boys
+have kept in the hope of seeing this light displayed. The milky juice
+of a South American Euphorbia (_E. phosphorea_) is stated by Martins
+to be phosphorescent when gently heated. But phosphorescence is
+evidently not so interesting and important a phenomenon in the
+vegetable as it is in the animal kingdom.
+
+The whole phenomenon is one that gives rise to a good many questions
+which it is not easy to answer, and this is especially true in the
+case of animal phosphorescence. What is the nature of the light? What
+are the conditions under which it is manifested? What purpose does it
+serve in the animal economy?
+
+As to the nature of the light, the principal question is whether it is
+a direct consequence of the vital activity of the organism in which it
+is seen, of such a nature that no further explanation can be given of
+it, any more than we can explain why a muscle is contracted under the
+influence of a nerve-stimulus; or whether it is due to some chemical
+process more or less analogous to the burning of a candle.
+
+The fact of luminosity appearing to be in certain cases directly under
+the control of the creature in which it is found, and the fact of its
+being manifested in many forms, as M. de Quatrefages found, only when
+muscular contraction was taking place, would seem to favor the former
+view. On the other hand, it is against this view that the
+phosphorescence is often found to persist after the animal is dead,
+and even in the phosphorescent organs for a considerable time after
+they have been extracted from the body of the animal. In the glow-worm
+the light goes on shining for some time after the death of the insect,
+and even when it has become completely extinguished it can be restored
+for a time by the application of a little moisture. Further, both
+Matteucci and Phipson found that when the luminous substance was
+extracted from the insect it would keep on glowing for thirty or forty
+minutes.
+
+In Pholas the light is still more persistent, and it is found that
+when the dead body of this mollusk is placed in honey, it will retain
+for more than a year the power of emitting light when plunged in warm
+water.
+
+The investigations of recent years have rendered it more and more
+probable that the light exhibited by phosphorescent organisms is due
+to a chemical process somewhat analogous to that which goes on in the
+burning of a candle. This latter process is one of rapid oxidation.
+The particles of carbon supplied by the oily matter that feeds the
+candle become so rapidly combined with oxygen derived from the air
+that a considerable amount of light, along with heat, is produced
+thereby. Now, the phenomenon of phosphorescence in organic forms,
+whether living or dead, appears also to be due to a process of
+oxidation, but one that goes on much more slowly than in the case of a
+lighted candle. It is thus more closely analogous to what is observed
+in the element phosphorus itself, which owes its name (meaning
+"light-bearer") to the fact that when exposed to the air at ordinary
+temperatures it glows in the dark, in consequence of its becoming
+slowly combined with oxygen.
+
+At one time it was believed that the presence of oxygen was not
+necessary to the exhibition of phosphorescence in organic forms, but
+it has now been placed beyond doubt that this is a mistake. Oxygen has
+been proved to be indispensable, and hence we see a reason for the
+luminous organs in the glow-worm being so intimately connected, as
+above mentioned, with the air-tubes that ramify through the insect.
+
+This fact of itself might be taken as a strong indication of the
+chemical nature of the process to which phosphorescence is due. But
+the problem has been made the subject of further investigations which
+have thrown more light upon it. It was long known that there were
+various inorganic bodies besides phosphorus which emitted a
+phosphorescent light in the dark, at least after being exposed to the
+rays of the sun; but it was not till quite recently that any organic
+compound was known to phosphoresce at ordinary temperatures.
+
+This discovery was made by a Polish chemist, named Bronislaus
+Radziszewski, who followed it up with a long series of experiments on
+the phosphorescence of organic compounds, by which he was able to
+determine the conditions under which that phenomenon was exhibited. In
+all the substances investigated by him in which phosphorescence was
+introduced he found that three conditions were essential to its
+production: (1) that oxygen should be present; (2) that there should
+be an alkaline reaction in the phosphorescing mixture--that is, a
+reaction such as is produced on acids and vegetable coloring matters
+by potash, soda, and the other alkalies; and (3) that some kind of
+chemical action should take place.
+
+He found, moreover, that among the organic compounds that could be
+made to phosphoresce under these conditions were nearly all the fixed
+and ethereal oils. With reference to the phosphorescence of animals,
+this observation is important, for it has been shown in a great many
+cases that a fatty substance forms the main constituent in their
+luminous organs. This has long been known to be the case in the
+luminous insects belonging to the Lampyridæ and Elateridæ, as well as
+in the luminous centipedes; and the researches of Panceri, already
+referred to, on the luminous organs of many marine forms have shown
+that it holds good with regard to these also.
+
+We may, therefore, conclude that substances fitted to phosphoresce
+under the conditions determined by the experiments of Radziszewski are
+generally, and probably universally, present in the luminous organs of
+phosphorescent animals. Now, what is to be said as to the occurrence
+of these conditions? The access of oxygen is in all cases easy to
+account for, but it must also be shown how the alkaline reaction is to
+be produced. We need not expect to find in animal organisms potash,
+soda, ammonia, and the other common alkalies; but it was established
+by experiment that the alkaline organic compounds cholin and neurin,
+which are present in animal tissues, would also serve to bring about
+the phenomenon of phosphorescence in the substances on which the
+experiments were made.
+
+Accordingly, it seems fair to conclude that when all these conditions
+for the production of phosphorescence in a chemical laboratory are
+present in animal organisms, the phenomenon, when observed in these,
+is exactly of the same nature as that which is produced artificially.
+By that it is meant that animal phosphorescence is attended, like the
+artificial phenomenon, by a slow chemical action, or in other words,
+that the phosphorescent light is due to a gradual process of
+oxidation.
+
+One curious circumstance has been discovered which lends still further
+probability to this explanation. It was mentioned above that among
+phosphorescent plants there are several species of Agaricus. Now,
+from one species of this genus, though not indeed one of the
+phosphorescent species (from _A. muscarius_) there has been extracted
+a principle called _amanitia_, which is found to be identical with
+cholin. In the light of the results derived from the investigations
+just referred to it is reasonable to draw the conclusion that, if
+sought for, this principle would likewise be found in the
+phosphorescent species in which the other conditions of
+phosphorescence are also present.
+
+On this theory of the production of the phenomenon now under
+consideration, the effect of shaking or of vital action in giving rise
+to or intensifying the exhibition of the light is accounted for by the
+fact that by these means fresh supplies of oxygen are brought into
+contact with the phosphorescent substance. The effect of ammonia on
+the light emitted by the sea-slug _Phyllirhoë bucephala_, is also
+fully explained, ammonia being one of those alkaline substances which
+are so directly favorable to the exhibition of the phenomenon.
+
+Nor is it difficult to account for the control which in some cases
+insects appear to have over the luminosity of the phosphorescent
+organs, exhibiting and withdrawing the light at will. It is not
+necessary to suppose that this is an immediate effect, a conversion of
+nerve force into light, and a withdrawal of that force. The action of
+the creature's will may be merely in maintaining or destroying the
+conditions under which the light is manifested. It may, for example,
+have the power of withdrawing the supply of oxygen, and this
+supposition receives some countenance from the observation cited from
+Kirby and Spence on the two captured glow-worms, one of which
+withdrew its light, while the other kept it shining, but while doing
+so had the posterior extremity of the abdomen in constant motion. But
+the animal may also have the power in another way of affecting the
+chemical conditions of the phenomenon. It may, for example, have the
+power of increasing or diminishing by some nervous influence the
+supply of the necessary alkaline ingredient.
+
+But if animal phosphorescence is really due to a process of slow
+oxidation, there is one singular circumstance to be noted in
+connection with it. Oxidation is a process that is normally
+accompanied by the development of heat. Even where no light is
+produced an increase of temperature regularly takes place when
+substances are oxidized. We ought, then, to expect such a rise of
+temperature when light is emitted by the phosphorescent organs of
+animals. But the most careful observations have shown that nothing of
+the kind can be detected. It was with a view to test this that Panceri
+dissected out the luminous organs of so many specimens of Pholas. He
+selected this mollusk because it was so abundant in the neighborhood
+of Naples, where, his experiments were made; and in making his
+experiments he made use of a thermopile, an apparatus by which, with
+the aid of electricity, much smaller quantities of heat can be
+indicated than by means of the most delicate thermometer. The organs
+remained luminous long after they were extracted, but no rise in
+temperature whatever could be found to accompany the luminosity. Many
+experiments upon different animals were made with similar negative
+results by means of the thermometer.
+
+The only explanation of this that can be given is probably to be found
+in the fact that the chemical process ascertained to go on in the
+phosphorescence of organic compounds on which experiments were made in
+the laboratory is an extremely slow one.
+
+The so-called phosphorescence of most inorganic bodies is one of a
+totally different nature from that exhibited in organic forms. The
+diamond shines for a time in the dark after it has been exposed to the
+sun; so do pieces of quartz when rubbed together, and powdered
+fluor-spar when heated shines with considerable brilliancy. Various
+artificial compounds, such as sulphide of calcium (Canton's
+phosphorus, as it is called from the discoverer), sulphate of barium
+(Bologna stone, or Bologna phosphorus), sulphide of strontium, etc.,
+after being illuminated by the rays of the sun, give out in the dark a
+beautiful phosphorescence, green, blue, violet, orange, red, according
+to circumstances. The luminous paint which has recently attracted so
+much attention is of the same nature. In these cases what we have is
+either a conversion of heat rays into light rays (as in the powdered
+fluor-spar), or the absorption and giving out again of sun-rays. In
+the latter case the phenomenon is essentially the same as
+fluorescence, in which the dark rays of the solar spectrum beyond the
+violet are made visible.
+
+But we must now return to the other questions that have been started
+in relation to phosphorescence in animals. There has been much
+speculation as to the object of this light, and to the purposes it
+serves in Nature. Probably no general answer can be given to this
+question. It is no doubt impossible to show why so many animals have
+been endowed with this remarkable property; but we may consider some
+of the effects which the possession of it has in different cases.
+
+In the first place, it will undoubtedly serve in many cases to afford
+light to enable the animal to see by, and in the Lampyridæ it would
+seem that the degree of luminosity is related to the development of
+the vision. In that family, according to the Rev. H.S. Gorham, the
+eyes are developed, as a rule, in inverse proportion to the
+luminosity. Where there is an ample supply of this kind of light the
+eyes are small, but where the light is insignificant the eyes are
+large by way of compensation. And moreover, where both eyes and light
+are small, then the antennae are large and feathery, so that the
+deficiency in the sense of sight is made up for by an unusual
+development in the organs of touch.
+
+But it is none the less certain that the presence of this light cannot
+always be designed to serve this purpose, for many of the animals so
+endowed are blind. The phosphorescent centipedes are without eyes,
+like all the other members of the genus (_Geophilus_) to which they
+belong, and probably the majority of phosphorescent marine forms are
+likewise destitute of organs of sight.
+
+Another suggestion is that the light derived from these marine forms,
+and especially from deep-sea Alcyonarians, is what enables the members
+of the deep-sea fauna that are possessed of eyes (which are always
+enormously enlarged) to see. Such is the suggestion of Dr. Carpenter,
+Sir Wyville Thomson, and Mr. Gwyn Jeffries; and it is possible that
+this actually is one of the effects of the phosphorescent property.
+But if so, it remains to inquire how the forms endowed with it came
+to be possessed of a power useful in that way to other forms, but not
+to themselves. According to the Darwinian doctrine of development, the
+powers that are developed in different organisms by the process of
+natural selection are such as are useful to themselves and not to
+others, unless incidentally.
+
+This consideration has led to another suggestion, namely, that the
+property of phosphorescence serves as a protection to the forms
+possessing it, driving away enemies in one way or another: it may be
+by warning them of the fact that they are unpalatable food, as is
+believed to be the case with the colors of certain brilliantly-colored
+caterpillars; it may be in other ways. In Kirby and Spence one case is
+recorded in which the phosphorescence of the common phosphorescent
+centipede (_Geophilus electricus_) was actually seen apparently to
+serve as a means of defence against an enemy. "Mr. Shepherd," says
+that authority, "once noticed a scarabeus running round the
+last-mentioned insect when shining, as if wishing, but afraid to
+attack it." In the case of the jelly-fishes, it has been pointed out
+that their well-known urticating or stinging powers would make them at
+least unpleasant, if not dangerous, food for fishes; and that
+consequently the luminosity by which so many of them are characterized
+at night may serve at once as a warning to predatory fishes and as a
+protection to themselves. The experience of the unpleasant properties
+of many phosphorescent animals may likewise have taught fishes to
+avoid all forms possessing this attribute, even though many of them
+might be quite harmless.
+
+Lastly, it has been suggested that the phosphorescence in the female
+glow-worm may be designed to attract the male; and that it will
+actually have this effect may readily be taken for granted.
+Observation shows that the male glow-worm is very apt to be attracted
+by a light. Gilbert White of Selborne mentions that they, attracted by
+the light of the candles, came into his parlor. Another observer
+states that by the same light he captured as many as forty male
+glow-worms in one night.
+
+[Illustration]
+
+
+
+
+COMETS
+
+(FROM MARVELS OF THE HEAVENS.)
+
+BY CAMILLE FLAMMARION.
+
+
+  "Je viens vous annoncer une grande nouvelle:
+  Nous l'avons, en dormant, madame, échappé belle.
+  Un monde près de nous a passé tout du long,
+  Est chu tout au travers de notre tourbillon;
+  Et s'il eût en chemin rencontré notre terre,
+  Elle eût été brisée en morceaux comme verre."
+                                           MOLIÈRE.
+
+[Illustration]
+
+This announcement of Trissontin's to Philaminte, who begins the parody
+on the fears caused by the appearance of comets, would not have been a
+parody four or five centuries ago. These tailed bodies, which suddenly
+come to light up the heavens, were for long regarded with terror, like
+so many warning signs of divine wrath. Men have always thought
+themselves much more important than they really are in the universal
+order; they have had the vanity to pretend that the whole creation was
+made for them, whilst in reality the whole creation does not suspect
+their existence. The Earth we inhabit is only one of the smallest
+worlds; and therefore it can scarcely be for it alone that all the
+wonders of the heavens, of which the immense majority remains hidden
+from it, were created. In this disposition of man to see in himself
+the centre and the end of everything, it was easy indeed to consider
+the steps of nature as unfolded in his favor; and if some unusual
+phenomenon presented itself, it was considered to be without doubt a
+warning from Heaven. If these illusions had had no other result than
+the amelioration of the more timorous of the community one would
+regret these ages of ignorance; but not only were these fancied
+warnings of no use, seeing that once the danger passed, man returned
+to his former state; but they also kept up among people imaginary
+terrors, and revived the fatal resolutions caused by the fear of the
+end of the world.
+
+When one fancies the world is about to end,--and this has been
+believed for more than a thousand years,--no solicitude is felt in the
+work of improving this world; and, by the indifference or disdain into
+which one falls, periods of famine and general misery are induced
+which at certain times have overtaken our community. Why use the
+wealth of a world which is going to perish? Why work, be instructed,
+or rise in the progress of the sciences or arts? Much better to forget
+the world, and absorb one's self in the barren contemplation of an
+unknown life. It is thus that ages of ignorance weigh on man, and
+thrust him further and further into darkness, while Science makes
+known by its influence on the whole community, its great value, and
+the magnitude of its aim.
+
+The history of a comet would be an instructive episode of the great
+history of the heavens. In it could be brought together the
+description of the progressive movement of human thought, as well as
+the astronomical theory of these extraordinary bodies. Let us take,
+for example, one of the most memorable and best-known comets, and give
+an outline of its successive passages near the Earth. Like the
+planetary worlds, Comets belong to the solar system, and are subject
+to the rule of the Star King. It is the universal law of gravitation
+which guides their path; solar attraction governs them, as it governs
+the movement of the planets and the small satellites. The chief point
+of difference between them and the planets is, that their orbits are
+very elongated; and, instead of being nearly circular, they take the
+elliptical form. In consequence of the nature of these orbits, the
+same comet may approach very near the Sun, and afterwards travel from
+it to immense distances. Thus, the period of the Comet of 1680 has
+been estimated at three thousand years. It approaches the Sun, so as
+to be nearer to it than our Moon is to us, whilst it recedes to a
+distance 853 times greater than the distance of the Earth from the
+Sun. On the 17th of December, 1680, it was at its perihelion--that is,
+at its greatest proximity to the Sun; it is now continuing its path
+beyond the Neptunian orbit. Its velocity varies according to its
+distance from the solar body. At its perihelion it travels thousands
+of leagues per minute; at its aphelion it does not pass over more than
+a few yards. Its proximity to the Sun in its passage near that body
+caused Newton to think that it received a heat twenty-eight thousand
+times greater than that we experience at the summer solstice; and
+that this heat being two thousand times greater than that of red-hot
+iron, an iron globe of the same dimensions would be fifty thousand
+years entirely losing its heat. Newton added that in the end comets
+will approach so near the Sun that they will not be able to escape the
+preponderance of its attraction, and that they will fall one after the
+other into this brilliant body, thus keeping up the heat which it
+perpetually pours out into space. Such is the deplorable end assigned
+to comets by the author of the "Principia," an end which makes De la
+Brétonne say to Rétif: "An immense comet, already larger than Jupiter,
+was again increased in its path by being blended with six other dying
+comets. Thus displaced from its ordinary route by these slight shocks,
+it did not pursue its true elliptical orbit; so that the unfortunate
+thing was precipitated into the devouring centre of the Sun." "It is
+said," added he, "that the poor comet, thus burned alive, sent forth
+dreadful cries!"
+
+[Illustration: A COMET]
+
+It will be interesting, then, in a double point of view, to follow a
+comet in its different passages in sight of the Earth. Let us take the
+most important in astronomical history--the one whose orbit has been
+calculated by Edmund Halley, and which was named after him. It was in
+1682 that this comet appeared in its greatest brilliancy, accompanied
+with a tail which did not measure less than thirty-two millions of
+miles. By the observation of the path which it described in the
+heavens, and the time it occupied in describing it, this astronomer
+calculated its orbit, and recognized that the comet was the same as
+that which was admired in 1531 and 1607, and which ought to have
+reappeared in 1759. Never did scientific prediction excite a more
+lively interest. The comet returned at the appointed time; and on the
+12th of March, 1759, reached its perihelion. Since the year 12 before
+the Christian era, it had presented itself twenty-four times to the
+Earth. It was principally from the astronomical annals of China that
+it was possible to follow it up to this period.
+
+Its first memorable appearance in the history of France is that of
+837, in the reign of Louis le Débonnaire. An anonymous writer of
+chronicles of that time, named "The Astronomer," gave the following
+details of this appearance, relative to the influence of the comet on
+the imperial imagination:
+
+"During the holy days of the solemnization of Easter, a phenomenon
+ever fatal, and of gloomy foreboding, appeared in the heavens. As soon
+as the Emperor, who paid attention to these phenomena, received the
+first announcement of it, he gave himself no rest until he had called
+a certain learned man and myself before him. As soon as I arrived, he
+anxiously asked me what I thought of such a sign; I asked time of him,
+in order to consider the aspects of the stars, and to discover the
+truth by their means, promising to acquaint him on the morrow; but the
+Emperor, persuaded that I wished to gain time, which was true, in
+order not to be obliged to announce anything fatal to him, said to me:
+'Go on the terrace of the palace and return at once to tell me what
+you have seen, for I did not see this star last evening, and you did
+not point it out to me; but I know that it is a comet; tell me what
+you think it announces to me.' Then scarcely allowing me time to say
+a word, he added: 'There is still another thing you keep back; it is
+that a change of reign and the death of a prince are announced by this
+sign.' And as I advanced the testimony of the prophet, who said: 'Fear
+not the signs of the heavens as the nations fear them,' the prince
+with his grand nature, and the wisdom which never forsook him, said,
+'We must not only fear Him who has created both us and this star. But
+as this phenomenon may refer to us, let us acknowledge it as a warning
+from Heaven."
+
+Louis le Débonnaire gave himself and his court to fasting and prayer,
+and built churches and monasteries. He died three years later, in 840,
+and historians have profited by this slight coincidence to prove that
+the appearance of the comet was a harbinger of death. The historian,
+Raoul Glader, added later: "These phenomena of the universe are never
+presented to man without surely announcing some wonderful and terrible
+event."
+
+Halley's comet again appeared in April, 1066, at the moment when
+William the Conqueror invaded England. It was pretended that it had
+the greatest influence on the fate of the battle of Hastings, which
+delivered over the country to the Normans.
+
+A contemporary poet, alluding probably to the English diadem with
+which William was crowned, had proclaimed in one place, "that the
+comet had been more favorable to William than nature had been to
+Caesar; the latter had no hair, but William had received some from the
+comet." A monk of Malmesbury apostrophized the comet in these terms:
+"Here thou art again, thou cause of the tears of many mothers! It is
+long since I have seen thee, but I see thee now, more terrible than
+ever; thou threatenest my country with complete ruin!"
+
+In 1455, the same comet made a more memorable appearance still. The
+Turks and Christians were at war, the West and the East seemed armed
+from head to foot--on the point of annihilating each other. The
+crusade undertaken by Pope Calixtus III. against the invading
+Saracens, was waged with redoubled ardor on the sudden appearance of
+the star with the flaming tail. Mahomet II. took Constantinople by
+storm, and raised the siege of Belgrade. But the Pope having put aside
+both the curse of the comet, and the abominable designs of the
+Mussulmans, the Christians gained the battle, and vanquished their
+enemies in a bloody fight. The _Angelus_ to the sound of bells dates
+from these ordinances of Calixtus III. referring to the comet.
+
+In his poem on astronomy, Daru, of the French Academy, describes this
+episode in eloquent terms:
+
+  "Un autre Mahomet a-t-il d'un bras puissant
+  Aux murs de Constantine arboré le croissant:
+  Le Danube étonné se trouble au bruit des armes,
+  La Grèce est dans les fers, l'Europe est en alarmes;
+  Et pour comble d'horreur, l'astre au visage ardent
+  De ses ailes de feu va couvrir l'Occident.
+  Au pied de ses autels, qu'il ne saurait défendre,
+  Calixte, l'oeil en pleurs, le front convert de cendre,
+  Conjure la comète, objet de tant d'effroi:
+  Regarde vers les cieux, pontife, et lève-toi!
+  L'astre poursuit sa course, et le fer d'Huniade
+  Arrête le vainqueur, qui tombe sous Belgrade.
+  Dans les cieux cependant le globe suspendu,
+  Par la loi générale à jamais retenu,
+  Ignore les terreurs, l'existence de Rome,
+  Et la Terre peut-être, et jusqu'au nom de l'homme,
+  De l'homme, être crédule, atome ambitieux,
+  Qui tremble sous un prêtre et qui lit dans les cieux."
+
+This ancient comet witnessed many revolutions in human history, at
+each of its appearances, even in its later ones, in 1682, 1759, 1835;
+it was also presented to the Earth under the most diverse aspects,
+passing through a great variety of forms, from the appearance of a
+curved sabre, as in 1456, to that of a misty head, as in its last
+visit. Moreover, this is not an exception to the general rule, for
+these mysterious stars have had the gift of exercising a power on the
+imagination which plunged it in ecstasy or trouble. Swords of fire,
+bloody crosses, flaming daggers, spears, dragons, fish, and other
+appearances of the same kind, were given to them in the middle ages
+and the Renaissance.
+
+Comets like those of 1577 appear, moreover, to justify by their
+strange form the titles with which they are generally greeted. The
+most serious writers were not free from this terror. Thus, in a
+chapter on celestial monsters, the celebrated surgeon, Ambroise Paré,
+described the comet of 1528 under the most vivid and frightful colors:
+"This comet was so horrible and dreadful that it engendered such great
+terror to the people, that they died, some with fear, others with
+illness. It appeared to be of immense length, and of blood color; at
+its head was seen the figure of a curved arm, holding a large sword in
+the hand as if it wished to strike. At the point of the sword there
+were three stars, and on either side was seen a great number of
+hatchets, knives, and swords covered with blood, amongst which were
+numerous hideous human faces, with bristling beards and hair."
+
+The imagination has good eyes when it exerts itself. The great and
+strange variety of cometary aspects is described with exactitude by
+Father Souciet in his Latin poem on comets. "Most of them," says he,
+"shine with fires interlaced like thick hair, and from this they have
+taken the name of comets. One draws after it the twisted folds of a
+long tail; another appears to have a white and bushy beard; this one
+throws a glimmer similar to that of a lamp burning during the night;
+that one, O Titan! represents thy resplendent face; and this other, O
+Phoebe! the form of thy nascent horns. There are some which bristle
+with twisted serpents. Shall I speak of those armies which have
+sometimes appeared in the air? of those clouds which follow as it were
+along a circle, or which resemble the head of Medusa? Have there not
+often been seen figures of men or savage animals?
+
+"Often, in the gloom of night, lighted up by these sad fires, the
+horrible sound of arms is heard, the clashing of swords which meet in
+the clouds, the ether furiously resounding with fearful din which
+crush the people with terror. All comets have a melancholy light, but
+they have not all the same color. Some have a leaden color; others
+that of flame or brass. The fires of some have the redness of blood;
+others resemble the brightness of silver. Some again are azure; others
+have the dark and pale color of iron. These differences come from the
+diversity of the vapors which surround them, or from the different
+manner in which they receive the Sun's rays. Do you not see in our
+fires, that various kinds of wood produce different colors? Pines and
+firs give a flame mixed with thick smoke, and throw out little light.
+That which rises from sulphur and thick bitumen is bluish. Lighted
+straw gives out sparks of a reddish color. The large olive, laurel,
+ash of Parnassus, etc., trees which always retain their sap, throw a
+whitish light similar to that of a lamp. Thus, comets whose fires are
+formed of different materials, each take and preserve a color which is
+peculiar to them."
+
+Instead of being a cause of fear and terror, the variety and
+variability of the aspect of comets ought rather to indicate to us the
+harmlessness of their nature.
+
+[Illustration]
+
+
+
+
+THE TOTAL SOLAR ECLIPSE OF 1883
+
+_AN ASTRONOMERS VOYAGE TO FAIRY-LAND._
+
+(FROM THE ATLANTIC MONTHLY, MAY, 1890.)
+
+BY PROF. E.S. HOLDEN.
+
+
+[Illustration]
+
+In 1883 calculations showed that a solar eclipse of unusually long
+duration (5 minutes, 20 seconds) would occur in the South Pacific
+Ocean. The track of the eclipse lay south of the equator, but north of
+Tahiti. There were in fact only two dots of coral islands on the
+charts in the line of totality, Caroline Island, and one hundred and
+fifty miles west Flint Island (longitude 150 west, latitude 10 south).
+Almost nothing was known of either of these minute points. The station
+of the party under my charge (sent out by the United States government
+under the direction of the National Academy of Sciences) was to be
+Caroline Islands.
+
+Every inch of that island (seven miles long, a mile or so broad) is
+familiar now; but it is almost ludicrous to recollect with what
+anxiety we pored over the hydrographic charts and sailing instructions
+of the various nations, to find some information, however scanty,
+about the spot which was to be our home for nearly a month. All that
+was known was that this island had formerly been occupied as a guano
+station. There was a landing _then_.
+
+After the _personnel_ of the party had been decided on, there were the
+preparations for its subsistence to be looked out for. How to feed
+seventeen men for twenty-one days? Fortunately the provisions that we
+took, and the fresh fish caught for us by the natives, just sufficed
+to carry us through with comfort and with health.
+
+In March of 1883 we sailed from New York, and about the same time a
+French expedition left Europe bound for the same spot. From New York
+to Panama, from Panama to Lima, were our first steps. Here we joined
+the United States steamship Hartford, Admiral Farragut's flagship, and
+the next day set sail for our destined port,--if a coral reef
+surrounded by a raging surf can be called a port. About the same time
+a party of French observers under Monsieur Janssen, of the Paris
+Academy of Sciences, left Panama in the _Eclaireur_.
+
+[Illustration: BIRD'S EYE VIEW OF THE CAROLINE ISLANDS.]
+
+It was an ocean race of four thousand miles due west. The station
+Caroline Islands was supposed to be more desirable than Flint Island.
+Admiral Wilkes's expedition had lain off the latter several days
+without being able to land on account of the tremendous surf, so that
+it was eminently desirable to "beat the Frenchman," as the sailors put
+it. With this end in view our party had secured (through a member of
+the National Academy in Washington) the verbal promise of the proper
+official of the Navy Department that the Hartford's orders should read
+"to burn coal as necessary." The last obstacle to success was thus
+removed. We were all prepared, and now the ship would take us speedily
+to our station.
+
+Imagine our feelings the next day after leaving Callao, when the
+commanding officer of the Hartford opened his sealed orders. They read
+(dated Washington, in February), "To arrive at Caroline Islands (in
+April) with full coal-bunkers!"
+
+Officialism could go no further. Here was an expedition sent on a
+slow-sailing ship directly through the regions of calms for four
+thousand miles. It was of no possible use to send the expedition at
+all unless it arrived in time. And here were our orders "to arrive
+with full coal-bunkers."
+
+Fortunately we had unheard-of good-luck. The trade-wind blew for us as
+it did for the Ancient Mariner, and we sped along the parallel of 12°
+south at the rate of one hundred and fifty miles a day under sail,
+while the _Eclaireur_ was steaming for thirty days a little nearer the
+equator in a dead calm. We arrived off the island just in time, with
+not a day to spare. It was a narrow escape, and a warning to all of us
+never to sail again under sealed orders unless we knew what was under
+the seal.
+
+Here we were, then, lying off the island and scanning its sparse crown
+of cocoanut palms, looking for a French flag among their wavy tufts.
+There was none in sight. We were the winners in the long race.
+Directly a whale-boat was lowered, and rowed around the white fringe
+of tremendous surf that broke ceaselessly against the vertical wall of
+coral rock. There was just one narrow place where the waves rolled
+into a sort of cleft and did not break. Here was the "landing," then.
+
+Landing was an acrobatic feat. In you went on the crest of a wave,
+pointing for the place where the blue seas did not break into white.
+An instant after, you were in the quiet water inside of the surf. Jump
+out everybody and hold the boat! Then it was pick up the various
+instruments, and carry them for a quarter of a mile to high-water mark
+and beyond, over the sharp points of the reef.
+
+In one night we were fairly settled; in another the Hartford had
+sailed away, leaving us in our fairy paradise, where the corals and
+the fish were of all the brilliant hues of the rainbow, and where the
+whiteness of the sand, the emerald of the lagoon, and the turquoise of
+the ocean made a picture of color and form never to be forgotten.
+
+But where are the Frenchmen? The next morning there is the _Eclaireur_
+lying a mile or so out, and there is a boat with the bo'sun--_maître
+d'équipage_--pulling towards the surf. I wade out to the brink. He
+halloes:
+
+"Where is the landing, then?"
+
+"_Mais ici_"--Right here,--I say.
+
+"Yes, that's all very well for _persons_, but where do you land _les
+bagages_?"
+
+"_Mais ici_" I say again, and he says, "_Diable!_"
+
+But all the same he lands both persons and baggage in a neat,
+sailor-like way. In a couple of days our two parties of fifty persons
+had taken possession of this fairy isle. Observatories go up,
+telescopes, spectroscopes, photographic cameras are pointed and
+adjusted. The eventful day arrives. Everything is successful. Then
+comes the Hartford and takes us away, and a few days later comes the
+_Eclaireur_, and the Frenchmen are gone. The little island is left
+there, abandoned to the five natives who tend the sickly plantation of
+cocoa-palms, and live from year to year with no incident but the
+annual visit of "the blig" (Kanaka for brig), which brings their store
+of ship biscuit and molasses.
+
+[Illustration: "OBSERVATORIES GO UP."]
+
+Think of their stupendous experience! For years and years they have
+lived like that in the marvellous, continuous charm of the silent
+island. The "blig" had come and gone away this year, and there will
+be no more disturbance and discord for a twelve-month longer.
+
+  "Surely, surely, slumber is more sweet than toil, the shore
+  Than labor in the deep mid-ocean, wind, and wave, and oar,
+  Then rest ye, brother mariners, we will not wander more!"
+
+Not so! for here comes a great warship out of the East under a press
+of canvas. What event is this? See! she clews up her light sails and
+fires an eleven-inch gun! One of those guns of Mobile Bay. Then swarms
+out the starboard watch, one hundred and sixty strong, and a fleet of
+boats brings ashore these pale astronomers with those useless tubes
+that they point at the sky every night. But there are useful things
+too; cooking-stoves, and lumber, and bricks.
+
+What is all this? No sooner are these established than comes another
+ship and fires its gun! and another set of hardy sailormen pours out,
+and here is another party of madmen with tubes,--yes, and with
+cooking-stoves and lumber, too. Then comes the crowning, stupendous,
+and unspeakable event. The whole sun is hidden and the heavens are
+lighted up with pearly streamers! In the name of all the Polynesian
+gods, what is the meaning of all this?
+
+And then in a few days all these are gone. All the madmen. They have
+taken away the useless tubes, but they have left their houses
+standing. Their splendid, priceless, precious cook-stoves are here.
+See! here is a frying-pan! here are empty tin cans! and a keg of
+nails! They must have forgotten all this, madmen as they are!
+
+And the little island sinks back to its quiet and its calm. The lagoon
+lies placid like a mirror. The slow sea breaks eternally on the outer
+reef. The white clouds sail over day by day. The seabirds come back to
+their haunts,--the fierce man-of-war birds, the gentle, soft-eyed
+tern. But we, whose island home was thus invaded--are we the same? Was
+this a dream? Will it happen again next year? every year? What indeed
+was it that happened,--or in fact, did it happen at all? Is it not a
+dream, indeed?
+
+If we left those peaceful Kanakas to their dream, we Americans have
+brought ours away with us. Who will forget it? Which of us does not
+wish to be in that peaceful fairyland once more? That is the personal
+longing. But we have all come back, each one with his note-books full;
+and in a few weeks the stimulus of accustomed habit has taken
+possession of us again. Right and wrong are again determined by
+"municipal sanctions." We have become useful citizens once more.
+Perhaps it is just as well. We should have been poor poets, and we do
+not forget. So ends the astronomer's voyage to fairyland.
+
+[Illustration]
+
+
+
+
+HALOS--PARHELIA--THE SPECTRE OF THE BROCKEN, ETC
+
+(FROM THE ATMOSPHERE.)
+
+BY CAMILLE FLAMMARION.
+
+
+[Illustration]
+
+Treatises on meteorology have not, up to the present day, classified
+with sufficient regularity the divers optical phenomena of the air.
+Some of these phenomena have, however, been seen but rarely, and have
+not been sufficiently studied to admit of their classification. We
+have examined the common phenomenon of the rainbow and we have seen
+that it is due to the refraction and reflection of light on drops of
+water, and that it is seen upon the opposite side of the sky to the
+sun in day-time, or the moon at night. We are now about to consider an
+order of phenomena which are of rarer occurrence, but which have this
+property in common with the rainbow, viz., that they take place also
+upon the side of the sky opposite to the sun. These different optical
+effects are classed together under the name of _anthelia_ (from
+Greek, opposite to, and Greek, the sun). The optical phenomena which
+occur on the same side as, or around the sun, such as halos, parhelia,
+etc., will be dealt with later on.
+
+Before coming to the anthelia, properly so called, or to the colored
+rings which appear around a shadow, it is as well first to note the
+effects produced on the clouds and mists that are facing the sun when
+it rises or sets.
+
+Upon high mountains, the shadow of the mountain is often seen thrown
+either upon the surface of the lower mists or upon the neighboring
+mountains, and projected opposite to the sun almost horizontally. I
+once saw the shadow of the Righi very distinctly traced upon Mount
+Pilate, which is situated to the west of the Righi, on the other side
+of the Lake of Lucerne. This phenomenon occurs a few minutes after
+sunrise, and the triangular form of Righi is delineated in a shape
+very easy to recognize.
+
+The shadow of Mont Blanc is discerned more easily at sunset. MM.
+Bravais and Martins, in one of their scientific ascents, noticed it
+under specially favorable circumstances, the shadow being thrown upon
+the snow-covered mountains, and gradually rising in the atmosphere
+until it reached a height of 1°, still remaining quite visible. The
+air above the cone of the shadow was tinted with that rosy purple
+which is seen, in a fine sunset, coloring the lofty peaks. "Imagine,"
+says Bravais, "the other mountains also projecting, at the same
+moment, their shadows into the atmosphere, the lower parts dark and
+slightly greenish, and above each of these shadows the rosy surface,
+with the deeper rose of the belt which separates it from them; add to
+this the regular contour of the cones of the shadow, principally at
+the upper edge, and lastly, the laws of perspective causing all these
+lines to converge the one to the other toward the very summit of the
+shadow of Mont Blanc; that is to say, to the point of the sky where
+the shadows of our own selves were; and even then one will have but a
+faint idea of the richness of the meteorological phenomenon displayed
+before our eyes for a few instants. It seemed as though an invisible
+being was seated upon a throne surrounded by fire, and that angels
+with glittering wings were kneeling before him in adoration."
+
+Among the natural phenomena which now attract our attention, but fail
+to excite our surprise, there are some which possess the
+characteristics of a supernatural intervention. The names which they
+have received still bear witness to the terror which they once
+inspired; and even to-day, when science has stripped them of their
+marvellous origin, and explained the causes of their production, these
+phenomena have retained a part of their primitive importance, and are
+welcomed by the _savant_ with as much interest as when they were
+attributed to divine agency. Out of a large and very diverse number, I
+will first select the _Spectre of the Brocken_.
+
+The Brocken is the highest mountain in the picturesque Hartz chain,
+running through Hanover, being three hundred and thirty feet above the
+level of the sea.
+
+One of the best descriptions of this phenomenon is given by the
+traveller Hane, who witnessed it on the 23d of May, 1797. After having
+ascended no less than thirty miles to the summit, he had the good
+fortune at last to contemplate the object of his curiosity. The sun
+rose at about four o'clock, the weather being fine, and the wind
+driving off to the west the transparent vapors which had not yet had
+time to be condensed into clouds. About a quarter-past four, Hane saw
+in this direction a human figure of enormous dimensions. A gust of
+wind nearly blowing off his hat at that moment, he raised his hand to
+secure it, and the colossal figure imitated his action. Hane, noticing
+this, at once made a stooping movement, and this was also reproduced
+by the spectre. He then called another person to him, and placing
+themselves in the very spot where the apparition was first seen, the
+pair kept their eyes fixed on the Achtermannshohe, but saw nothing.
+After a short interval, however, two colossal figures appeared, which
+repeated the gestures made by them, and then disappeared.
+
+Some few years ago, in the summer of 1862, a French artist, M.
+Stroobant, witnessed and carefully sketched this phenomenon, which is
+drawn in full-page illustration, opposite p. 272. He had slept at the
+inn of the Brocken, and rising at two in the morning, he repaired to
+the plateau upon the summit in the company of a guide. They reached
+the highest point just as the first glimmer of the rising sun enabled
+them to distinguish clearly objects at a great distance. To use M.
+Stroobant's own words, "My guide, who had for some time appeared to be
+walking in search of something, suddenly led me to an elevation whence
+I had the singular privilege of contemplating for a few instants the
+magnificent effect of mirage, which is termed the Spectre of the
+Brocken. The appearance is most striking. A thick mist, which seemed
+to emerge from the clouds like an immense curtain, suddenly rose to
+the west of the mountain, a rainbow was formed, then certain
+indistinct shapes were delineated. First, the large tower of the inn
+was reproduced upon a gigantic scale; after that we saw our two selves
+in a more vague and less exact shape, and these shadows were in each
+instance surrounded by the colors of the rainbow, which served as a
+frame to this fairy picture. Some tourists who were staying at the inn
+had seen the sun rise from their windows, but no one had witnessed the
+magnificent spectacle which had taken place on the other side of the
+mountain."
+
+Sometimes these spectres are surrounded by colored concentric arcs.
+Since the beginning of the present century, treatises on meteorology
+designate, under the name of the _Ulloa circle_, the pale external
+arch which surrounds the phenomenon, and this same circle has
+sometimes been called the "white rainbow." But it is not formed at the
+same angular distance as the rainbow, and, although pale, it often
+envelops a series of interior colored arcs.
+
+[Illustration: "THE SPECTRE OF THE BROCKEN"]
+
+Ulloa, being in company with six fellow-travellers upon the Pambamarca
+at daybreak one morning, observed that the summit of the mountain was
+entirely covered with thick clouds, and that the sun, when it rose,
+dissipated them, leaving only in their stead light vapors, which it
+was almost impossible to distinguish. Suddenly, in the opposite
+direction to where the sun was rising, "each of the travellers beheld,
+at about seventy feet from where he was standing, his own image
+reflected in the air as in a mirror. The image was in the centre of
+three rainbows of different colors, and surrounded at a certain
+distance by a fourth bow with only one color. The inside color of each
+bow was carnation or red, the next shade was violet, the third yellow,
+the fourth straw color, the last green. All these bows were
+perpendicular to the horizon; they moved in the direction of, and
+followed, the image of the person they enveloped as with a glory." The
+most remarkable point was that, although the seven spectators were
+standing in a group, each person only saw the phenomenon in regard to
+his own person, and was disposed to disbelieve that it was repeated in
+respect to his companions. The extent of the bows increased
+continually and in proportion to the height of the sun; at the same
+time their colors faded away, the spectre became paler and more
+indistinct, and finally the phenomenon disappeared altogether. At the
+first appearance the shape of the bows was oval, but toward the end
+they became quite circular. The same apparition was observed in the
+polar regions by Scoresby, and described by him. He states that the
+phenomenon appears whenever there is mist and at the same time shining
+sun. In the polar seas, whenever a rather thick mist rises over the
+ocean, an observer, placed on the mast, sees one or several circles
+upon the mist.
+
+[Illustration: THE ULLOA CIRCLE.]
+
+These circles are concentric, and their common centre is in the
+straight line joining the eye of the observer to the sun, and extended
+from the sun toward the mist. The number of circles varies from one to
+five; they are particularly numerous and well colored when the sun is
+very brilliant and the mist thick and low. On July 23, 1821, Scoresby
+saw four concentric circles around his head. The colors of the first
+and of the second were very well defined; those of the third, only
+visible at intervals, were very faint, and the fourth only showed a
+slight greenish tint.
+
+The meteorologist Kaemtz has often observed the same fact in the Alps.
+Whenever this shadow was projected upon a cloud, his head appeared
+surrounded by a luminous aureola.
+
+To what action of light is this phenomenon due? Bouguer is of opinion
+that it must be attributed to the passage of light through icy
+particles. Such, also, is the opinion of De Saussure, Scoresby, and
+other meteorologists.
+
+In regard to the mountains, as we cannot assure ourselves directly of
+the fact by entering the clouds, we are reduced to conjecture. The
+aerostat traversing the clouds completely, and passing by the very
+point where the apparition is seen, affords one an opportunity of
+ascertaining the state of the cloud. This observation I have been able
+to make, and so to offer an explanation of the phenomenon.
+
+As the balloon sails on, borne forward by the wind, its shadow travels
+either on the ground or on the clouds. This shadow is, as a rule,
+black, like all others; but it frequently happens that it appears
+alone on the surface of the ground, and thus appears luminous.
+Examining this shadow by the aid of a telescope, I have noticed that
+it is often composed of a dark nucleus and a penumbra of the shape of
+an aureola. This aureola, frequently very large in proportion to the
+diameter of the central nucleus, eclipses it to the naked eye, so that
+the whole shadow appears like a nebulous circle projected in yellow
+upon the green ground of the woods and meadows. I have noticed, too,
+that this luminous shadow is generally all the more strongly marked in
+proportion to the greater humidity of the surface of the ground.
+
+Seen upon the clouds, this shadow sometimes presents a curious aspect.
+I have often, when the balloon emerged from the clouds into the clear
+sky, suddenly perceived, at twenty or thirty yards' distance, a second
+balloon distinctly delineated, and apparently of a grayish color,
+against the white ground of the clouds. This phenomenon manifests
+itself at the moment when the sun re-appears. The smallest details of
+the car can be made out clearly, and our gestures are strikingly
+reproduced by the shadow.
+
+[Illustration: THE SHADOW OF THE BALLOON WAS SEEN BY US.]
+
+On April 15, 1868, at about half-past three in the afternoon, we
+emerged from a stratum of clouds, when the shadow of the balloon was
+seen by us, surrounded by colored concentric circles, of which the car
+formed the centre. It was very plainly visible upon a yellowish white
+ground. A first circle of pale blue encompassed this ground and the
+car in a kind of ring. Around this ring was a second of a deeper
+yellow, then a grayish red zone, and lastly as the exterior
+circumference, a fourth circle, violet in hue, and imperceptibly
+toning down into the gray tint of the clouds. The slightest details
+were clearly discernible--net, robes, and instruments. Every one of
+our gestures was instantaneously reproduced by the aerial spectres.
+The anthelion remained upon the clouds sufficiently distinct, and for
+a sufficiently long time, to permit of my taking a sketch in my
+journal and studying the physical condition of the clouds upon which
+it was produced. I was able to determine directly the circumstances of
+its production. Indeed, as this brilliant phenomenon occurred in the
+midst of the very clouds which I was traversing, it was easy for me to
+ascertain that these clouds were not formed of frozen particles. The
+thermometer marked 2° above zero. The hygrometer marked a maximum of
+humidity experienced, namely, seventy-seven at three thousand seven
+hundred and seventy feet, and the balloon was then at four thousand
+six hundred feet, where the humidity was only seventy-three. It is
+therefore certain that this is a phenomenon of the diffraction of
+light simply produced by the vesicles of the mist.
+
+The name of diffraction is given to all the modifications which the
+luminous rays undergo when they come in contact with the surface of
+bodies. Light, under these circumstances, is subject to a sort of
+deviation, at the same time becoming decomposed, whence result those
+curious appearances in the shadows of objects which were observed for
+the first time by Grimaldi and Newton.
+
+The most interesting phenomena of diffraction are those presented by
+_gratings_, as are technically denominated the systems of linear and
+very narrow openings situated parallel to one another and at very
+small intervals. A system of this kind may be realized by tracing with
+a diamond, for instance, on a pane of glass equidistant lines very
+close together. As the light would be able to pass in the interstices
+between the strokes, whereas it would be stopped in the points
+corresponding to those where the glass was not smooth, there is, in
+reality, an effect produced as if there were a series of openings very
+near to each other. A hundred strokes, about 1/25th of an inch in
+length, may thus be drawn without difficulty. The light is then
+decomposed in spectra, each overlapping the other. It is a phenomenon
+of this kind which is seen when we look into the light with the eye
+half closed; the eyelashes in this case, acting as a net-work or
+grating. These net-works may also be produced by reflection, and it is
+to this circumstance that are due the brilliant colors observed when a
+pencil of luminous rays is reflected on a metallic surface regularly
+striated.
+
+To the phenomena of gratings must be attributed, too, the colors,
+often so brilliant, to be seen in mother-of-pearl. This substance is
+of a laminated structure; so much so, that in carving it the different
+folds are often cut in such a way as to form a regular net-work upon
+the surface. It is, again, to a phenomenon of this sort that are due
+the rainbow hues seen in the feathers of certain birds, and sometimes
+in spiders' webs. The latter, although very fine, are not simple, for
+they are composed of a large number of pieces joined together by a
+viscous substance, and thus constitute a kind of net-work.
+
+If the sun is near the horizon, and the shadow of the observer falls
+upon the grass, upon a field of corn, or other surface covered with
+dew, there is visible an aureola, the light of which is especially
+bright about the head, but which diminishes from below the middle of
+the body. This light is due to the reflection of light by the moist
+stubble and the drops of dew. It is brighter about the head, because
+the blades that are near where the shadow of the head falls expose to
+it all that part of them which is lighted up, whereas those farther
+off expose not only the part which is lighted up, but other parts
+which are not, and this diminishes the brightness in proportion as
+their distance from the head increases. The phenomenon is seen
+whenever there is simultaneously mist and sun. This fact is easily
+verified upon a mountain. As soon as the shadow of a mountaineer is
+projected upon a mist, his head gives rise to a shadow surrounded by a
+luminous aureola.
+
+[Illustration: FOG-BOW SEEN FROM THE MATTERHORN.]
+
+_The Illustrated London News_ of July 8, 1871, illustrates one of
+these apparitions, "The Fog-Bow, seen from the Matterhorn," observed
+by E. Whymper in this celebrated region of the Alps. The observation
+was taken just after the catastrophe of July 14, 1865; and by a
+curious coincidence, two immense white aerial crosses projected into
+the interior of the external arc. These two crosses were no doubt
+formed by the intersection of circles, the remaining parts of which
+were invisible. The apparition was of a grand and solemn character,
+further increased by the silence of the fathomless abyss into which
+the four ill-fated tourists had just been precipitated.
+
+[Illustration]
+
+Other optical appearances of an analogous kind are manifested under
+different conditions. Thus, for instance, if any one, turning his back
+to the sun, looks into water, he will perceive the shadow of his head,
+but always very much deformed. At the same time he will see starting
+from this very shadow what seem to be luminous bodies, which dart
+their rays in all directions with inconceivable rapidity, and to a
+great distance. These luminous appearances--these aureola rays--have,
+in addition to the darting movement, a rapid rotary movement around
+the head.
+
+[Illustration]
+
+
+
+
+THE PLANET VENUS
+
+BY AGNES M. CLERKE.
+
+
+
+
+I.
+
+HESPERUS AND PHOSPHOR.
+
+
+[Illustration]
+
+The radiant planet that hangs on the skirts of dusk and dawn
+
+     "like a jewel in an Ethiop's ear,"
+
+has been known and sung by poets in all ages. Its supremacy over the
+remainder of the starry host is recognized in the name given it by the
+Arabs, those nomad watchers of the skies, for while they term the moon
+"El Azhar," "the Brighter One," and the sun and moon together "El
+Azharan," "the Brighter Pair," they call Venus "Ez Zahra," the bright
+or shining one _par excellence_, in which sense the same word is used
+to describe a flower. This "Flower of Night" is supposed to be no
+other than the white rose into which Adonis was changed by Venus in
+the fable which is the basis of all early Asiatic mythology. The
+morning and evening star is thus the celestial symbol of that union
+between earth and heaven in the vivifying processes of nature,
+typified in the love of the goddess for a mortal.
+
+The ancient Greeks, on the other hand, not unnaturally took the star,
+which they saw alternately emerging from the effulgence of the rising
+and setting sun, in the east and in the west, for two distinct bodies,
+and named it differently according to the time of its appearance. The
+evening star they called Hesperus, and from its place on the western
+horizon, fabled an earthly hero of that name, the son of Atlas, who
+from the slopes of that mountain on the verge of the known world used
+to observe the stars until eventually carried off by a mighty wind,
+and so translated to the skies. These divine honors were earned by his
+piety, wisdom, and justice as a ruler of men, and his name long shed a
+shimmering glory over those Hesperidean regions of the earth, where
+the real and unreal touched hands in the mystical twilight of the
+unknown.
+
+But the morning star shone with a different significance as the herald
+of the day, the torchbearer who lights the way for radiant Aurora on
+her triumphal progress through the skies. Hence he was called
+Eosphorus, or Phosphorus, the bearer of the dawn, translated into
+Latin as Lucifer, the Light-bearer. The son of Eos, or Aurora, and the
+Titan Astraeus, he was of the same parentage as the other multitude of
+the starry host, to whom a similar origin was ascribed, and from whom
+in Greek mythology he was evidently believed to differ only in the
+superior order of his brightness. Homer, who mentions the planet in
+the following passage:
+
+  "But when the star of Lucifer appeared,
+  The harbinger of light, whom following close,
+  Spreads o'er the sea the saffron-robed morn."
+
+                              (LORD DERBY'S "Iliad.")
+
+recognizes no distinction between those celestial nomads, the planets,
+"wandering stars," as the Arabs call them, which visibly change their
+position relatively to the other stars, and the latter, whose places
+on the sphere are apparently fixed and immutable. In this he and his
+compatriots were far behind the ancient Egyptians, who probably
+derived their knowledge from still earlier speculators in Asia, for
+they not only observed the movements of some at least of the planets,
+but believed that Mercury and Venus revolved as satellites round the
+sun, which in its turn circled round our lesser world. Pythagoras is
+said to have been the first to identify Hesperus with Phosphor, as the
+
+  "Silver planet both of eve and morn,"
+
+and by Plato the same fact is recognized. The other planets, all of
+which had, according to him, been originally named in Egypt and Syria,
+have each its descriptive title in his nomenclature. Thus the
+innermost, "the Star of Mercury," is called Stilbon, "the Sparkler,"
+Mars, Pyroeis, "the Fiery One," while Jupiter, the planet of the
+slowest course but one, is designated as Phaeton, and Saturn, the
+tardiest of all, Phaenon. These names were in later times abandoned in
+favor of those of the divinities to whom they were respectively
+dedicated, unalterably associated now with the days of the week, over
+which they have been selected to preside.
+
+The Copernican theory, which once and forever "brushed the cobwebs out
+of the sky," by clearing away the mists of pre-existing error, first
+completely explained the varying positions of the Shepherd's star,
+irradiating the first or last watch of night, according to her
+alternate function as the follower or precursor of the sun. As she
+travels on a path nearer to him by more than twenty-five and a half
+million miles than that of the earth, she is seen by us on each side
+of him in turn after passing behind or in front of him. The points at
+which her orbit expands most widely to our eyes--an effect of course
+entirely due to perspective, as her distance from the sun is not then
+actually increased--are called her eastern and western elongations;
+that at which she passes by the sun on the hither side her inferior,
+and on the farther side her superior conjunction. At both conjunctions
+she is lost to our view, since she accompanies the sun so closely as
+to be lost in his beams, rising and setting at the same time, and
+travelling with him in his path through the heavens during the day.
+When at inferior conjunction, or between us and the sun, she turns her
+dark hemisphere to us like the new moon, and would consequently be
+invisible in any case, but when in the opposite position, shows us her
+illuminated face, and is literally a day star, invisible only because
+effaced by the solar splendor. It is as she gradually separates from
+him, after leaving this latter position, circling over that half of
+her orbit which lies to the east of him, that she begins to come into
+view as an evening star, following him at a greater and greater
+distance, and consequently setting later, until she attains her
+greatest eastern elongation, divided from the sun about 45° of his
+visible circuit through the heavens, and consequently remaining above
+the horizon for some four hours after him. From this point she again
+appears to draw nearer to him until she passes on his hither side in
+inferior conjunction, from which she emerges on the opposite side to
+the westward, and begins to shine as a morning star, preceding him on
+his track, at a gradually increasing distance, until attaining her
+greatest westward elongation, and finally completing her cycle by
+returning to superior conjunction once more in a period of about five
+hundred and eighty-four days.
+
+Venus is thus Hesperus or Vesper, the evening star, when following the
+sun as she passes from beyond him in superior conjunction to inferior
+conjunction where she is nearest to the earth. As she again leaves him
+behind in her course from this point to the opposite one of superior
+conjunction, she appears in her second aspect as Phosphorus or
+Lucifer, "the sun of morning," and herald of the day, shining as
+
+                          "The fair star
+  That gems the glittering coronet of morn."
+
+
+
+
+II.
+
+THE PHASES OF VENUS.
+
+
+But the changes in the aspect of Venus due to her varying positions in
+her orbit are not confined to those which cause her to oscillate with
+a pendulum movement eastward and westward from the sun. The discovery
+that she undergoes phases exactly like those of the moon, followed
+that of the existence of Jupiter's satellites as the second great
+result achieved by the use of the telescope in the hands of Galileo.
+The fact that the planets were intrinsically dark bodies revolving
+round the sun, and reflecting its light, as he and Copernicus had
+maintained, thus received a further ocular demonstration. The
+Florentine astronomer describes in a letter to a friend how the
+planet, after emerging from superior conjunction as a morning star,
+gradually loses her rotundity on the side remote from the luminary,
+changing first to a half sphere and then to a waning crescent; until,
+after passing through the stage of absolute extinction when
+intervening between us and the sun, she re-appears as a morning star,
+and undergoes the same series of transformations in inverse order. The
+revelation was indeed so novel and unexpected, that when the slight
+deformation of the planet's shape was first detected by him, he did
+not venture to announce it in plain terms but veiled it, according to
+the prevailing fashion of the time, under a Latin anagram. His
+celebrated sentence--
+
+  "Haec immatura a me jam frustra leguntur."
+
+("Those incomplete observations are as yet read by me in vain.")
+
+forms, by transposing the letters, the more definite statement,
+
+  "Cynthiæ figuras æmulatur Mater Amorum."
+
+("The mother of the loves imitates the aspects of Diana.")
+
+that is to say, Venus vies with the phases of the moon. The discovery
+was an important one from its bearing on popular superstition ascribing
+to the planets special influences on human affairs, for since they were
+thus shown to transmit to us only borrowed light, belief in their
+beneficent or malefic powers over man's destinies received a rude shock.
+
+[Illustration: THE PHASES OP VENUS.]
+
+Galileo's announcement, published in September, 1610, when only a
+slight flattening of the planet's disk was visible, received absolute
+confirmation in the ensuing months, as she completed her full
+half-circle of change on February 24th of the following year, and
+consequently exhibited herself to him in all her varying aspects. It
+was the first time they had been looked upon by a human eye, since its
+unaided powers do not enable it to discern them, although one
+exception to this rule is said to have existed. This was the case of
+the Swiss mathematician Gauss, who, when a child, on being shown the
+crescent star through the telescope, exclaimed to his mother that it
+"was turned wrong"; the inference being that he recognized the
+reversal of the image in the field of the glass. If it were indeed so,
+he deserves to rank with the Siberian savage, who described the
+eclipses, or Jupiter's satellites; or the shoemaker of Breslau, who
+could see and declare the positions of those minute orbs.
+
+The phases exhibited to us by Venus are due to her moving in an orbit
+within that of the earth, at one side of which she is between us and
+the sun, while at the other this position is exactly reversed. We may
+compare her to a performer in a great celestial circus, lit by a
+central chandelier, and ourselves to spectators in an external ring,
+from which we see her at one time facing us with the light full on
+her, at the opposite point in complete shadow, and at the intermediate
+ones in varying degrees of illumination according to our changing
+views of her. The same illustration may serve to show why Venus is
+brightest, not when full, since she is then beyond the sun, and at the
+farthest possible point from us, but when she approaches us at
+inferior conjunction, more nearly by over one hundred and thirty
+million miles, and still shows us a crescent of her illuminated
+surface, before passing into the last phase of total obscuration. When
+actually nearest to us she is absolutely invisible, being then, like
+the new moon, between us and the sun. Her varying degrees of
+brilliancy, even when in the same phase, are thus accounted for by her
+alternate retreat from and advance towards us as she circles round the
+sun. Completing, as she does, her revolution in about seven months and
+a half, she would of course go through the whole series of her
+metamorphoses in that time, were the earth, from which we observe
+them, a fixed point. Their protraction instead, over a term of five
+hundred and eighty-four days, or more than nineteen months, is due to
+the simultaneous motion of the earth in the same direction, over her
+larger orbit in a longer period, causing the same relative position of
+the sister planet to recur only as often as she overtakes her in her
+career. Thus the hour and minute hands of a watch, moving at different
+rates of speed after meeting on the dial plate at twelve o'clock, will
+not again come together until five minutes past one, when the swifter
+paced of the two will have completed a revolution and a twelfth. But
+were we to retard the motion of the latter, reducing it to only twice
+that of its companion, they would always meet at the figure twelve, as
+it would exactly complete two circuits while the hour hand was
+performing one. Venus thus overtakes and passes the earth once in five
+hundred and eighty-four days, or nearly two and a half of her own
+years, constituting what is called her synodic period of apparent
+revolution as seen from this globe. She thus presents to us all the
+phases undergone by our own satellite during a lunar month, passing
+from new to full, and _vice versa_, through the various intervening
+gradations of form.
+
+The phases of Venus are amongst the most beautiful subjects for
+observation in a moderate telescope, as her silver bow, gradually
+brightening in the evening dusk, or fading in the dawn,
+
+  "On a bed of daffodil sky,"
+
+is, after the two greater luminaries that rule the day and night, the
+most brilliant object in the heavens.
+
+
+
+
+III.
+
+THE SILVER CROWN.
+
+
+The parallel between Venus and
+
+  "That orbed maiden with fire laden,
+   Whom mortals call the moon,"
+
+is carried a stage further. Most of us are familiar with the spectacle
+in which the Ancient Egyptians saw symbolized Horus on the lap of
+Isis, but which we more prosaically term "the old moon in the new
+moon's arms." The strongly illuminated half circle next the sun is
+then seen embracing with its horns a dusky sphere, contrasting with it
+as tarnished silver does with the newly burnished metal. The same
+phenomenon is occasionally, though very rarely, exhibited by Venus,
+while close to the sun at inferior injunction, when the shadowy form
+of the full orb is seen to shine dimly within her crescent with what
+is termed "the ashen light." More wonderful still, this "glimmering
+sphere" is then crowned, as with a silver halo, by a thin luminous
+arch, forming a secondary sickle facing the one nearest the sun, and
+doubtless due to the refraction of his rays round the globe of the
+planet, through the upper regions of her twilight atmosphere. This
+spectacle was first observed by the Jesuit Ricciolo, an opponent of
+the Copernican theory, on January 9th, 1643. He describes the planet
+as ruddy near the sun, yellowish in the middle, and of greenish blue
+on the side remote from the sun; while he also noted the bow of light
+limiting the dark hemisphere. Scarcely daring to trust his own
+eyesight, he ascribed these appearances, although he recorded them, to
+illusory reflection in the telescope.
+
+[Illustration: VENUS AT HER GREATEST BRILLIANCY.]
+
+They were again seen, however, by Derham about 1715, and six years
+later by Kirch, in Berlin, who has the following entry in his diary
+for Saturday, June 29, 1721:--"I found Venus in a region where the sky
+was not very clear. The planet was narrow, and I seemed to see its
+dark side, though this is almost incredible. The diameter of Venus was
+65", and its sickle seemed to tremble in the atmospheric vapors."
+Again, on March 8th, 1726, he records a similar observation. "We
+observed Venus with the twenty-six foot telescope. I perceived her
+dark side, and its edge seemed to describe a smaller circle than that
+of the light side, as is the case of the moon." This effect is due to
+irradiation, that is to say, to the glare from a bright surface,
+giving a deceptive enlargement to its apparent area. He again saw the
+dark side of the planet in October, 1759, as did Harding at Göttingen,
+with Herschel's ten-foot reflector, on January 24th, 1806. This latter
+observer saw it on this occasion stand out against the background of
+the sky as of a pale ashen green, while on February 28th following, it
+seemed to him of a pale reddish gray, like the color of the eclipsed
+moon.
+
+That the latter body should send to us from her nocturnal shadows
+sufficient light to be visible is easily explicable, since she is then
+flooded with earth-light reflected on her from a surface thirteen and
+one-half times greater than her own, and probably casting on her an
+illumination transcending our full moonlight in the same proportion.
+But the secondary light of Venus admits of no such explanation, since
+earth-light on her surface, diminished by 1/12000th part compared to
+what it is on that of the moon, would be quite insufficient to render
+her visible to our eyes. The phenomenon was therefore adduced as an
+argument for the habitability of the planets by Gruithuisen, of the
+Munich Observatory, who, writing early in this century, suggested that
+the ashen light of Venus might be due to general illuminations in
+celebration by her inhabitants of some periodically recurring
+festivity, The materials for a flare-up on so grand a scale would, he
+thought, exist in abundance, as he conjectured the vegetation of our
+planetary neighbor to be more luxuriant than that of our Brazilian
+forests. The phosphorescence of the Aphroditean oceans, warm and
+teeming with life, as they are held to be by Zollner, was advanced as
+an explanatory hypothesis, with scarcely more plausibility, by
+Professor Safarik, while others have resorted to the supposition of
+atmospheric or electrical luminosity producing on a large scale some
+such display as that of the aurora borealis.
+
+Professor Vogel, of Berlin, who himself saw part of the night-side of
+Venus, in its semi-obscurity in November, 1871, ascribed its
+visibility to a twilight effect caused by a very extensive atmosphere.
+The light thus transmitted to us by aerial diffusion and giving the
+ashen light, is reflected sunlight, while that sent by the luminous
+arc on its edge is direct sunlight, refracted, or bent round to us,
+from behind the planet. The silver selvedge of the dawn edging the
+dark limb may consequently be the brightest part of the broken nimbus
+that then seems to surround her.
+
+A similar appearance is observed during transits of Venus, when she
+passes directly between us and the actual solar disk. A silver thread
+is then seen encircling that side of the planet which has not yet
+entered on the face of the sun or "a shadowy nebulous ring," as it was
+described by Mr. Macdonnell at Eden, surrounds the whole planetary
+disk when two-thirds of it have passed the solar edge. As it moves off
+it, the same aureole again becomes visible, testifying to the
+existence of an atmosphere of considerable extent exterior to the
+sharply outlined surface ordinarily visible. The shimmering haze of
+reflected sunlight which perpetually enfolds her is only made apparent
+to us under exceptional circumstances which cut off some portion of
+her more immediate light, just as we see the motes in the air
+illuminated by a candle if we hide the actual flame from our eyes. The
+perennial twilight which seems to reign over the nocturnal hemisphere
+of Venus may compensate, perhaps, for the want of a satellite to
+modify its darkness.
+
+The great prolongation at other times of the horns of her crescent, so
+as to embrace almost her entire circumference with a tenuous ring of
+light, is doubtless due to the same cause, as their visibility should
+otherwise be limited to a half segment of a circle. The regions thus
+shining to us are obviously those on which the sun has not yet set,
+his appearance above the horizon being prolonged, as in our own case,
+by refraction, though to a much larger extent. The magnitude of the
+sun's disk as seen from Venus, a third larger than it appears to us,
+is also adducted by Mr. Proctor in his posthumous work, "The Old and
+the New Astronomy," edited and completed by Mr. A.C. Ranyard, as an
+element in extending the illumination of Venus to more than a
+hemisphere of her surface. As his diameter there is 44-1/4°, a zone
+of more than 22° wide outside the sunward hemisphere is he thinks
+illuminated by direct though partial sunlight, the orb being
+throughout this tract still partially above the horizon.
+
+[Illustration: GEOGRAPHICAL ASPECT OF VENUS.]
+
+
+
+
+[Illustration]
+
+
+THE STARS
+
+(FROM STARLAND.)
+
+BY SIR ROBERT S. BALL.
+
+
+[Illustration]
+
+The group of bodies which cluster around our sun forms a little
+island, so to speak, in the extent of infinite space. We may
+illustrate this by a map in which we shall endeavor to show the stars
+placed at their proper relative distances. We first open the compasses
+one inch, and thus draw a little circle to represent the path of the
+earth. We are not going to put in all the planets. We take Neptune,
+the outermost, at once. To draw its path I open the compasses to
+thirty inches, and draw a circle with that radius. That will do for
+our solar system, though the comets no doubt will roam beyond these
+limits. To complete our map we ought of course to put in some stars.
+There are a hundred million to choose from, and we shall begin with
+the brightest. It is often called the Dog Star, but astronomers know
+it better as Sirius. Let us see where it is to be placed on our map.
+Sirius is beyond Neptune, so it must be outside somewhere. Indeed, it
+is a good deal further off than Neptune; so I try at the edge of the
+drawing-board; I have got a method of making a little calculation that
+I do not intend to trouble you with, but I can assure you that the
+results it leads me to are quite correct; they show me that this board
+is not big enough. But could a board which was big enough fit into
+this lecture theatre? Here, again, I make my little calculations, and
+I find that there would not be room for a board sufficiently great; in
+fact, if I put the sun here at one end, with its planets around it?
+Sirius would be too near on the same scale if it were at the further
+corner. The board would have to go out through the wall of the
+theatre, out through London. Indeed, big as London is, it would not be
+large enough to contain the drawing-board that I should require. It
+would have to stretch about twenty miles from where we are now
+assembled. We may therefore dismiss any hope of making a practical map
+of our system on this scale if Sirius is to have its proper place. Let
+us, then, take some other star. We shall naturally try with the
+nearest of all. It is one that we do not know in this part of the
+world, but those that live in the southern hemisphere are well
+acquainted with it. The name of this star is Alpha Centauri. Even for
+this star we should require a drawing three or four miles long if the
+distance from the earth to the sun is to be taken as one inch. You see
+what an isolated position our sun and his planets occupy. The members
+of the family are all close together, and the nearest neighbors are
+situated at enormous distances. There is a good reason for this
+separation. The stars are very pretty and perfectly harmless to us
+where they are at present situated. They might be very troublesome
+neighbors if they were very much closer to our system. It is therefore
+well they are so far off; they would be constantly making disturbances
+in the sun's family if they were near at hand. Sometimes they would be
+dragging us into unpleasantly great heat by bringing us too close to
+the sun, or producing a coolness by pulling us away from the sun,
+which would be quite as disagreeable.
+
+
+The Stars are Suns.
+
+We are about to discuss one of the grandest truths in the whole of
+nature. We have had occasion to see that this sun of ours is a
+magnificent globe immensely larger than the greatest of his planets,
+while the greatest of these planets is immensely larger than this
+earth; but now we are to learn that our sun is, indeed, only a star
+not nearly so bright as many of those which shine over our heads every
+night. We are comparatively close to the sun, so that we are able to
+enjoy his beautiful light and cheering heat. Each of those other
+myriads of stars is a sun, and the splendor of those distant suns is
+often far greater than that of our own. We are, however, so enormously
+far from them that they appear dwindled down to insignificance. To
+judge impartially between our sun or star and such a sun or star as
+Sirius we should stand halfway between the two; it is impossible to
+make a fair estimate when we find ourselves situated close to one star
+and a million times as far from the other. After allowance is made for
+the imperfections of our point of view, we are enabled to realize the
+majestic truth that the sun is no more than a star, and that the other
+stars are no less than suns. This gives us an imposing idea of the
+extent and magnificence of the universe in which we are situated. Look
+lip at the sky at night--you will see a host of stars; try to think
+that every one of them is itself a sun. It may probably be that those
+suns have planets circling round them, but it is hopeless for us to
+expect to see such planets. Were you standing on one of those stars
+and looking towards our system, you would not perceive the sun to be
+the brilliant and gorgeous object that we know so well. If you could
+see him at all, he would merely seem like a star, not nearly as bright
+as many of those you can see at night. Even if you had the biggest of
+telescopes to aid your vision, you could never discern from one of
+these bodies the planets which surround the sun, no astronomer in the
+stars could see Jupiter, even if his sight were a thousand times as
+powerful as any sight or telescope that we know. So minute an object
+as our earth would, of course, be still more hopelessly beyond the
+possibility of vision.
+
+
+The Number of the Stars.
+
+To count the stars involves a task which lies beyond the power of man
+to accomplish. Even without the aid of any telescope, we can see a
+great multitude of stars from this part of the world. There are also
+many constellations in the southern hemisphere which never appear
+above our horizon. If, however, we were to go to the equator, then, by
+waiting there for a twelve-month, all the stars in the heavens would
+have been successively exposed to view. An astronomer, Houzeau, with
+the patience to count them, enumerated about six thousand. This is the
+naked-eye estimate of the star-population of the heavens; but if
+instead of relying on unaided vision, you get the assistance of a
+little telescope, you will be astounded at the enormous multitude of
+stars which are disclosed.
+
+[Illustration: FIG 1. THE GREAT BEAR AND THE POLE.]
+
+An ordinary opera-glass or binocular is a very useful instrument for
+looking at the stars in the heavens. If you employ an instrument of
+this sort, you will be amazed to find that the heavens teem with
+additional hosts of stars that your unaided vision would never have
+given you knowledge of. Any part of the sky may be observed; but, just
+to give an illustration, I shall take one special region, namely, that
+of the Great Bear (Fig. 1). The seven well-known stars are here shown,
+four of which form a sort of oblong, while the other three represent
+the tail. I would like you to make this little experiment. On a fine
+clear night, count how many stars there are within this oblong; they
+are all very faint, but you will be able to see a few, and, with good
+sight, and on a clear night, you may see perhaps ten. Next take your
+opera-glass and sweep it over the same region; if you will carefully
+count the stars it shows, you will find fully two hundred; so that
+the opera-glass has, in this part of the sky, revealed nearly twenty
+times as many stars as could be seen without its aid. As six thousand
+stars can be seen by the eye all over the heavens, we may fairly
+expect that twenty times that number--that is to say, one hundred and
+twenty thousand stars--could be shown by the opera-glass over the
+entire sky. Let us go a step further, and employ a telescope, the
+object-glass of which is three inches across. This is a useful
+telescope to have, and, if a good one, will show multitudes of
+pleasing objects, though an astronomer would not consider it very
+powerful. An instrument like this, small enough to be carried in the
+hand, has been applied to the task of enumerating the stars in the
+northern half of the sky, and three hundred and twenty thousand stars
+were counted. Indeed, the actual number that might have been seen with
+it is considerably greater, for when the astronomer Argelander made
+this memorable investigation he was unable to reckon many of the stars
+in localities where they lay very close together. This grand count
+only extended to half the sky, and, assuming that the other half is as
+richly inlaid with stars, we see that a little telescope like that we
+have supposed will, when swept over the heavens, reveal a number of
+stars which exceeds that of the population of any city in England
+except London. It exhibits more than one hundred times as many stars
+as our eyes could possibly reveal. Still, we are only at the beginning
+of the count; the very great telescopes add largely to the number.
+There are multitudes of stars which in small instruments we cannot
+see, but which are distinctly visible from our great observatories.
+That telescope would be still but a comparatively small one which
+would show as many stars in the sky as there are people living in the
+mighty city of London; and with the greatest instruments, the tale of
+stars has risen to a number far greater than that of the entire
+population of Great Britain.
+
+In addition to those stars which the largest telescopes show us, there
+are myriads which make their presence evident in a wholly different
+way. It is only in quite recent times that an attempt has been made to
+develop fully the powers of photography in representing the celestial
+objects. On a photographic plate which has been exposed to the sky in
+a great telescope the stars are recorded by thousands. Many of these
+may, of course, be observed with a good telescope, but there are not a
+few others which no one ever saw in a telescope, which apparently no
+one ever could see, though the photograph is able to show them. We do
+not, however, employ a camera like that which the photographer uses
+who is going to take your portrait. The astronomer's plate is put into
+his telescope, and then the telescope is turned towards the sky. On
+that plate the stars produce their images, each by its own light. Some
+of these images are excessively faint, but we give a very long
+exposure of an hour or two hours; sometimes as much as four hours'
+exposure is given to a plate so sensitive that a mere fraction of a
+second would sufficiently expose it during the ordinary practice of
+taking a photograph in daylight. We thus afford sufficient time to
+enable the fainter objects to indicate their presence upon the
+sensitive film. Even with an exposure of a single hour a picture
+exhibiting sixteen thousand stars has been taken by Mr. Isaac Roberts,
+of Liverpool. Yet the portion of the sky which it represents is only
+one ten-thousandth part of the entire heavens. It should be added that
+the region which Mr. Roberts has photographed is furnished with stars
+in rather exceptional profusion.
+
+Here, at last, we have obtained some conception of the sublime scale
+on which the stellar universe is constructed. Yet even these plates
+cannot represent all the stars that the heavens contain. We have every
+reason for knowing that with larger telescopes, with more sensitive
+plates, with more prolonged exposures, ever fresh myriads of stars
+will be brought within our view.
+
+You must remember that every one of these stars is truly a sun, a
+lamp, as it were, which doubtless gives light to other objects in its
+neighborhood as our sun sheds light upon this earth and the other
+planets. In fact, to realize the glories of the heavens you should try
+to think that the brilliant points you see are merely the luminous
+points of the otherwise invisible universe.
+
+Standing one fine night on the deck of a Cunarder we passed in open
+ocean another great Atlantic steamer. The vessel was near enough for
+us to see not only the light from the mast-head but also the little
+beams from the several cabin ports; and we could see nothing of the
+ship herself. Her very existence was only known to us by the twinkle
+of these lights. Doubtless her passengers could see, and did see, the
+similar lights from our own vessel, and they probably drew the correct
+inference that these lights indicated a great ship.
+
+Consider the multiplicity of beings and objects in a ship: the
+captain and the crew, the passengers, the cabins, the engines, the
+boats, the rigging, and the stores. Think of all the varied interests
+there collected and then reflect that out on the ocean, at night, the
+sole indication of the existence of this elaborate structure was given
+by the few beams of light that happened to radiate from it. Now raise
+your eyes to the stars; there are the twinkling lights. We cannot see
+what those lights illuminate, we can only conjecture what untold
+wealth of non-luminous bodies may also lie in their vicinity; we may,
+however, feel certain that just as the few gleaming lights from a ship
+are utterly inadequate to give a notion of the nature and the contents
+of an Atlantic steamer, so are the twinkling stars utterly inadequate
+to give even the faintest conception of the extent and the interest of
+the universe. We merely see self-luminous bodies, but of the
+multitudes of objects and the elaborate systems of which these bodies
+are only the conspicuous points we see nothing and we know very
+little. We are, however, entitled to infer from an examination of our
+own star--the sun--and of the beautiful system by which it is
+surrounded, that these other suns may be also splendidly attended.
+This is quite as reasonable a supposition as that a set of lights seen
+at night on the Atlantic Ocean indicates the existence of a fine ship.
+
+
+The Clusters of Stars.
+
+On a clear night you can often see, stretching across the sky, a track
+of faint light, which is known to astronomers as the "Milky Way." It
+extends below the horizon, and then round the earth to form a girdle
+about the heavens. When we examine the Milky Way with a telescope we
+find, to our amazement, that it consists of myriads of stars, so small
+and so faint that we are not able to distinguish them individually; we
+merely see the glow produced from their collective rays. Remembering
+that our sun is a star, and that the Milky Way surrounds us, it would
+almost seem as if our sun were but one of the host of stars which form
+this cluster.
+
+There are also other clusters of stars, some of which are exquisitely
+beautiful telescopic spectacles. I may mention a celebrated pair of
+these objects which lies in the constellation of Perseus. The sight of
+them in a great telescope is so imposing that no one who is fit to
+look through a telescope could resist a shout of wonder and admiration
+when first they burst on his view. But there are other clusters. Here
+is a picture of one which is known as the "Globular Cluster in the
+Centaur" (Fig. 2). It consists of a ball of stars, so far off that,
+however large these several suns may actually be, they have dwindled
+down to extremely small points of light. A homely illustration may
+serve to show the appearance which a globular cluster presents in a
+good telescope. I take a pepper-caster, and on a sheet of white paper
+I begin to shake out the pepper until there is a little heap at the
+centre and other grains are scattered loosely about. Imagine that
+every one of those grains of pepper was to be transformed into a tiny
+electric light, and then you have some idea of what a cluster of stars
+would look like when viewed through a telescope of sufficient power.
+There are multitudes of such groups scattered through the depths of
+space. They require our biggest telescopes to show them adequately. We
+have seen that our sun is a star, being only one of a magnificent
+cluster that forms the Milky Way. We have also seen that there are
+other groups scattered through the length and depth of space. It is
+thus we obtain a notion of the rank which our earth holds in the
+scheme of things celestial.
+
+[Illustration: FIG. 2. GLOBULAR CLUSTER IN THE CENTAUR.]
+
+
+The Rank of the Earth as a Globe in Space.
+
+Let me give an illustration with the view of explaining more fully the
+nature of the relation which the earth bears to the other globes which
+abound through space, and you must allow me to draw a little upon my
+imagination. I shall suppose that the mails of our country extend not
+only over this globe, but that they also communicate with other
+worlds; that postal arrangements exist between Mars and the earth,
+between the sun and Orion--in fact, everywhere throughout the whole
+extent of the universe. We shall consider how our letters are to be
+addressed. Let us take the case of Mr. John Smith, merchant, who lives
+at 1001, Piccadilly; and let us suppose that Mr. John Smith's business
+transactions are of such an extensive nature that they reach not only
+all over this globe, but away throughout space. I shall suppose that
+the firm has a correspondent residing--let us say in the constellation
+of the Great Bear; and when this man of business wants to write to Mr.
+Smith from these remote regions, what address must he put upon the
+letter, so that the Postmaster-General of the universe shall make no
+mistake about its delivery? He will write as follows:--
+
+  MR. JOHN SMITH,
+    1001 Piccadilly,
+      London,
+        England,
+          Europe,
+            Earth,
+              Near the Sun,
+                Milky Way,
+                  The Universe.
+
+Let us now see what the several lines of this address mean. Of course
+we put down the name of Mr. John Smith in the first line, and then we
+will add "1001 Piccadilly" for the second; but as the people in the
+Great Bear are not likely to know where Piccadilly is, we shall add
+"London" underneath. As even London itself cannot be well known
+everywhere, it is better to write "England." This would surely find
+Mr. John Smith from any post-office on this globe. From other globes,
+however, the supreme importance of England may not be so immediately
+recognized, and therefore it is as well to add another line, "Europe."
+This ought to be sufficient, I think, for any post-office in the solar
+system. Europe is big enough to be visible from Mars or Venus, and
+should be known to the post-office people there, just as we know and
+have names for the continents on Mars. But further away there might be
+a little difficulty; from Uranus and Neptune the different regions on
+our earth can never have been distinguished, and therefore we must add
+another line to indicate the particular globe of the solar system
+which contains Europe. Mark Twain tells us that there was always one
+thing in astronomy which specially puzzled him, and that was to know
+how we found out the names of the stars. We are, of course, in
+hopeless ignorance of the name by which this earth is called among
+other intelligent beings elsewhere who can see it. I can only adopt
+the title of "Earth," and therefore I add this line. Now our address
+is so complete that from anywhere in the solar system--from Mercury,
+from Jupiter, or Neptune--there ought to be no mistake about the
+letter finding its way to Mr. John Smith. But from his correspondent
+in the Great Bear this address would be still incomplete; they cannot
+see our earth from there, and even the sun himself only looks like a
+small star--like one, in fact, of thousands of stars elsewhere.
+However, each star can be distinguished, and our sun may, for
+instance, be recognized from the Great Bear by some designation. We
+shall add the line "Near the Sun," and then I think that from this
+constellation, or from any of the other stars around us, the address
+of Mr. John Smith may be regarded as complete. But Mr. Smith's
+correspondence may be still wider. He may have an agent living in the
+cluster of Perseus or on some other objects still fainter and more
+distant; then "Near the Sun" is utterly inadequate as a concluding
+line to the address, for the sun, if it can be seen at all from
+thence, will be only of the significance of an excessively minute
+star, no more to be designated by a special name than are each of the
+several leaves on the trees of a forest. What this distant
+correspondent will be acquainted with is not the earth or the sun but
+only the cluster of stars among which the sun is but a unit. Again we
+use our own name to denote the cluster, and we call it the "Milky
+Way." When we add this line, we have made the address of Mr. John
+Smith as complete as circumstances will permit. I think a letter
+posted to him anywhere ought to reach its destination. To perfect it,
+however, we will finish up with one line more--"The Universe."
+
+
+The Distances of the Stars.
+
+I must now tell you something about the distances of the stars. I
+shall not make the attempt to explain fully how astronomers make such
+measurements, but I will give you some notion of how it is done. You
+may remember I showed you how we found the distance of a globe that
+was hung from the ceiling. The principle of the method for finding the
+distance of a star is somewhat similar, except that we make the two
+observations not from the two ends of a table, not even from opposite
+sides of the earth, but from two opposite points on the earth's orbit,
+which are therefore at a distance of one hundred and eighty-six
+million miles. Imagine that on Midsummer Day, when standing on the
+earth here, I measure with a piece of card the angle between the star
+and the sun. Six months later, on Midwinter Day, when the earth is at
+the opposite point of its orbit, I again measure the angle between the
+same star and the sun, and we can now determine the star's distance by
+making a triangle. I draw a line a foot long, and we will take this
+foot to represent one hundred and eighty-six million miles, the
+distance between the two stations; then placing the cards at the
+corners, I rule the two sides and complete the triangle, and the star
+must be at the remaining corner; then I measure the sides of the
+triangle, and how many feet they contain, and recollecting that each
+foot corresponds to one hundred and eighty-six million miles, we
+discover the distance of the star. If the stars were comparatively
+near us, the process would be a very simple one; but, unfortunately,
+the stars are so extremely far off that this triangle, even with a
+base of only one foot, must have its sides many miles long. Indeed,
+astronomers will tell you that there is no more delicate or
+troublesome work in the whole of their science than that of
+discovering the distance of a star.
+
+In all such measurements we take the distance from the earth to the
+sun as a conveniently long measuring-rod, whereby to express the
+results. The nearest stars are still hundreds of thousands of times as
+far off as the sun. Let us ponder for a little on the vastness of
+these distances. We shall first express them in miles. Taking the
+sun's distance to be ninety-three million miles, then the distance of
+the nearest fixed star is about twenty millions of millions of
+miles--that is to say, we express this by putting down a 2 first, and
+then writing thirteen ciphers after it. It is, no doubt, easy to speak
+of such figures, but it is a very different matter when we endeavor to
+imagine the awful magnitude which such a number indicates. I must try
+to give some illustrations which will enable you to form a notion of
+it. At first I was going to ask you to try and count this number, but
+when I found it would require at least three hundred thousand years,
+counting day and night without stopping, before the task was over, it
+became necessary to adopt some other method.
+
+When on a visit in Lancashire I was once kindly permitted to visit a
+cotton mill, and I learned that the cotton yarn there produced in a
+single day would be long enough to wind round this earth twenty-seven
+times at the equator. It appears that the total production of cotton
+yarn each day in all the mills together would be on the average about
+one hundred and fifty-five million miles. In fact, if they would only
+spin about one-fifth more, we could assert that Great Britain produced
+enough cotton yarn every day to stretch from the earth to the sun and
+back again! It is not hard to find from these figures how long it
+would take for all the mills in Lancashire to produce a piece of yarn
+long enough to reach from our earth to the nearest of the stars. If
+the spinners worked as hard as ever they could for a year, and if all
+the pieces were then tied together, they would extend to only a small
+fraction of the distance; nor if they worked for ten years, or for
+twenty years, would the task be fully accomplished. Indeed, upwards of
+four hundred years would be necessary before enough cotton could be
+grown in America and spun in this country to stretch over a distance
+so enormous. All the spinning that has ever yet been done in the world
+has not formed a long enough thread!
+
+There is another way in which we can form some notion of the immensity
+of these sidereal distances. You will recollect that, when we were
+speaking of Jupiter's moons, I told you of the beautiful discovery
+which their eclipses enabled astronomers to make. It was thus found
+that light travels at the enormous speed of about one hundred and
+eighty-five thousand miles per second. It moves so quickly that within
+a single second a ray would flash two hundred times from London to
+Edinburgh and back again.
+
+We said that a meteor travels one hundred times as swiftly as a
+rifle-bullet; but even this great speed seems almost nothing when
+compared with the speed of light, which is ten thousand times as
+great. Suppose some brilliant outbreak of light were to take place in
+a distant star--an outbreak which would be of such intensity that the
+flash from it would extend far and wide throughout the universe. The
+light would start forth on its voyage with terrific speed. Any
+neighboring star which was at a distance of less than one hundred and
+eighty-five thousand miles would, of course, see the flash within a
+second after it had been produced. More distant bodies would receive
+the intimation after intervals of time proportioned to their
+distances. Thus, if a body were one million miles away, the light
+would reach it in from five to six seconds, while over a distance as
+great as that which separates the earth from the sun the news would be
+carried in about eight minutes. We can calculate how long a time must
+elapse ere the light shall travel over a distance so great as that
+between the star and our earth. You will find that from the nearest of
+the stars the time required for the journey will be over three years.
+Ponder on all that this involves. That outbreak in the star might be
+great enough to be visible here, but we could never become aware of it
+till three years after it had happened. When we are looking at such a
+star to-night we do not see it as it is at present, for the light that
+is at this moment entering our eyes has travelled so far that it has
+been three years on the way. Therefore, when we look at the star now
+we see it as it was three years previously. In fact, if the star were
+to go out altogether, we might still continue to see it twinkling for
+a period of three years longer, because a certain amount of light was
+on its way to us at the moment of extinction, and so long as that
+light keeps arriving here, so long shall we see the star showing as
+brightly as ever. When, therefore, you look at the thousands of stars
+in the sky to-night, there is not one that you see as it is now, but
+as it was years ago.
+
+I have been speaking of the stars that are nearest to us, but there
+are others much farther off. It is true we cannot find the distances
+of these more remote objects with any degree of accuracy, but we can
+convince ourselves how great that distance is by the following
+reasoning. Look at one of the brightest stars. Try to conceive that
+the object was carried away further into the depths of space, until it
+was ten times as far from us as it is at present, it would still
+remain bright enough to be recognized in quite a small telescope; even
+if it were taken to one hundred times its original distance it would
+not have withdrawn from the view of a good telescope; while if it
+retreated one thousand times as far as it was at first it would still
+be a recognizable point in our mightiest instruments. Among the stars
+which we can see with our telescopes, we feel confident there must be
+many from which the light has expended hundreds of years, or even
+thousands of years, on the journey. When, therefore, we look at such
+objects, we see them, not as they are now, but as they were ages ago;
+in fact, a star might have ceased to exist for thousands of years, and
+still be seen by us every night as a twinkling point in our great
+telescopes.
+
+Remembering these facts, you will, I think, look at the heavens with a
+new interest. There is a bright star, Vega, or Alpha Lyræ, a beautiful
+gem, so far off that the light from it which now reaches our eyes
+started before many of my audience were born. Suppose that there are
+astronomers residing on worlds amid the stars, and that they have
+sufficiently powerful telescopes to view this globe, what do you think
+they would observe? They will not see our earth as it is at present;
+they will see it as it was years (and sometimes many years) ago. There
+are stars from which if England could now be seen, the whole of the
+country would be observed at this present moment to be in a great
+state of excitement at a very auspicious event. Distant astronomers
+might notice a great procession in London, and they could watch the
+coronation of a youthful queen amid the enthusiasm of a nation. There
+are other stars still further, from which, if the inhabitants had good
+enough telescopes, they would now see a mighty battle in progress not
+far from Brussels. One splendid army could be beheld hurling itself
+time after time against the immovable ranks of the other. They would
+not, indeed, be able to hear the ever-memorable "Up, Guards, and at
+them!" but there can be no doubt that there are stars so far away that
+the rays of light which started from the earth on the day of the
+battle of Waterloo are only just arriving there. Further off still,
+there are stars from which a bird's-eye view could be taken at this
+very moment of the signing of Magna Charta. There are even stars from
+which England, if it could be seen at all, would now appear, not as
+the great England we know, but as a country covered by dense forests,
+and inhabited by painted savages, who waged incessant war with wild
+beasts that roamed through the island. The geological problems that
+now puzzle us would be quickly solved could we only go far enough into
+space and had we only powerful enough telescopes. We should then be
+able to view our earth through the successive epochs of past
+geological time; we should be actually able to see those great animals
+whose fossil remains are treasured in our museums tramping about over
+the earth's surface, splashing across its swamps, or swimming with
+broad flippers through its oceans. Indeed, if we could view our own
+earth reflected from mirrors in the stars, we might still see Moses
+crossing the Red Sea, or Adam and Eve being expelled from Eden.
+
+So important is the subject of star distance that I am tempted to give
+one more illustration in order to bring before you some conception of
+how vast such distances are. I shall take, as before, the nearest of
+the stars so far as known to us, and I hope to be forgiven for taking
+an illustration of a practical and a commercial kind instead of one
+more purely scientific. I shall suppose that a railway is about to be
+made from London to Alpha Centauri. The length of that railway, of
+course, we have already stated: it is twenty billions of miles. So I
+am now going to ask your attention to the simple question as to the
+fare which it would be reasonable to charge for the journey. We shall
+choose a very cheap scale on which to compute the price of a ticket.
+The parliamentary rate here is, I believe, a penny for every mile. We
+will make our interstellar railway fares much less even than this; we
+shall arrange to travel at the rate of one hundred miles for every
+penny. That, surely, is moderate enough. If the charges were so low
+that the journey from London to Edinburgh only cost fourpence, then
+even the most unreasonable passenger would be surely contented. On
+these terms how much do you think the fare from London to this star
+ought to be? I know of one way in which to make our answer
+intelligible. There is a National Debt with which your fathers are,
+unhappily, only too well acquainted; you will know quite enough about
+it yourselves in those days when you have to pay income tax. This debt
+is so vast that the interest upon it is about sixty thousand pounds a
+day, the whole amount of the National Debt being six hundred and
+thirty-eight millions of pounds.
+
+If you went to the booking-office with the whole of this mighty sum in
+your pocket--but stop a moment; could you carry it in your pocket?
+Certainly not, if it were in sovereigns. You would find that after you
+had as many sovereigns as you could conveniently carry there would
+still be some left--so many, indeed, that it would be necessary to get
+a cart to help you on with the rest. When the cart had as great a load
+of sovereigns as the horse could draw there would be still some more,
+and you would have to get another cart; but ten carts, twenty carts,
+fifty carts, would not be enough. You would want five thousand of
+these before you would be able to move off towards the station with
+your money. When you did get there and asked for a ticket at the rate
+of one hundred miles for a penny, do you think you would get any
+change? No doubt some little time would be required to count the
+money, but when it was counted the clerk would tell you that there was
+not enough--that he must have nearly two hundred millions of pounds
+more.
+
+That will give some notion of the distance of the nearest star, and we
+may multiply it by ten, by one hundred, and even by one thousand, and
+still not attain to the distance of some of the more remote stars that
+the telescope shows us.
+
+On account of the immense distances of the stars we can only perceive
+them to be mere points of light. We can never see a star to be a globe
+with marks on it like the moon, or like one of the planets--in fact,
+the better the telescope the smaller does the star seem, though, of
+course, its brightness is increased with every addition to the
+light-grasping power of the instrument.
+
+
+The Brightness and Color of Stars.
+
+Another point to be noticed is the arrangement of stars in classes,
+according to their lustre. The brightest stars, of which there are
+about twenty, are said to be of the first magnitude. Those just
+inferior to the first magnitude are ranked as the second; and those
+just lower than the second are estimated as the third; and so on. The
+smallest points that your unaided eyes will show you are of about the
+sixth magnitude. Then the telescope will reveal stars still fainter
+and fainter, down to what we term the seventeenth or eighteenth
+magnitudes, or even lower still. The number of stars of each magnitude
+increases very much in the classes of small ones.
+
+Most of the stars are white, but many are of a somewhat ruddy hue.
+There are a few telescopic points which are intensely red, some
+exhibit beautiful golden tints, while others are blue or green.
+
+There are some curious stars which regularly change their brilliancy.
+Let me try to illustrate the nature of these variables. Suppose that
+you were looking at a street gas-lamp from a very long distance, so
+that it seemed a little twinkling light; and suppose that some one was
+preparing to turn the gas-cock up and down. Or, better still, imagine
+a little machine which would act regularly so as to keep the light
+first of all at its full brightness for two days and a half, and then
+gradually turn it down until in three or four hours it declines to a
+feeble glimmer. In this low state the light remains for twenty
+minutes; then during three or four hours the gas is to be slowly
+turned on again until it is full. In this condition the light will
+remain for two days and a half, and then the same series of changes is
+to recommence. This would be a very odd form of gas-lamp. There would
+be periods of two days and a half during which it would remain at its
+full; these would be separated by intervals of about seven hours, when
+the gradual turning down and turning up again would be in progress.
+
+The imaginary gas-lamp is exactly paralleled by a star Algol, in the
+constellation of Perseus (Fig. 3), which goes through the series of
+changes I have indicated. Ordinarily speaking, it is a bright star of
+the second magnitude, and, whatever be the cause, the star performs
+its variations with marvellous uniformity. In fact, Algol has always
+arrested the attention of those who observed the heavens, and in early
+times was looked on as the eye of a demon. There are many other stars
+which also change their brilliancy. Most of them require much longer
+periods than Algol, and sometimes a new star which nobody has ever
+seen before will suddenly kindle into brilliancy. It is now known that
+the bright star Algol is attended by a dark companion. This dark star
+sometimes comes between Algol and the observer and cuts off the light.
+Thus it is that the diminution of brightness is produced.
+
+[Illustration: FIG. 3. PERSEUS AND ITS NEIGHBORING STARS INCLUDING
+ALGOL.]
+
+
+Double Stars.
+
+Whenever you have a chance of looking at the heavens through a
+telescope, you should ask to be shown what is called _a double star_.
+There are many stars in the heavens which present no remarkable
+appearance to the unaided eye, but which a good telescope at once
+shows to be of quite a complex nature. These are what we call double
+stars, in which two quite distinct stars are placed so close together
+that the unaided eye is unable to separate them. Under the magnifying
+power of the telescope, however, they are seen to be distinct. In
+order to give some notion of what these objects are like, I shall
+briefly describe three of them. The first lies in that best known
+constellation, the Great Bear. If you look at his tail, which consists
+of three stars, you will see that near the middle one of the three a
+small star is situated; we call this little star Alcor, but it is the
+brighter one near Alcor to which I specially call your attention. The
+sharpest eye would never suspect that it was composed of two stars
+placed close together. Even a small telescope will, however, show this
+to be the case, and this is the easiest and the first observation that
+a young astronomer should make when beginning to turn a telescope to
+the heavens. Of course you will not imagine that I mean Alcor to be
+the second component of the double star; it is the bright star near
+Alcor which is the double. Here are two marbles, and these marbles are
+fastened an inch apart. You can see them, of course, to be separate;
+but if the pair were moved further and further away, then you would
+soon not be able to distinguish between them, though the actual
+distance between the marbles had not altered. Look at these two wax
+tapers which are now lighted; the little flames are an inch apart. You
+would have to view them from a station a third of a mile away if the
+distance between the two flames were to appear the same as that
+between the two components of this double star. Your eye would never
+be able to discriminate between two lights only an inch apart at so
+great a distance; a telescope would, however, enable you to do so, and
+this is the reason why we have to use telescopes to show us double
+stars.
+
+You might look at that double star year after year throughout the
+course of a long life without finding any appreciable change in the
+relative positions of its components. But we know that there is no
+such thing as rest in the universe; even if you could balance a body
+so as to leave it for a moment at rest, it would not stay there, for
+the simple reason that all the bodies round it in every direction are
+pulling at it, and it is certain that the pull in one direction will
+preponderate, so that move it must. Especially is this true in the
+case of two suns like those forming a double star. Placed
+comparatively near each other they could not remain permanently in
+that position; they must gradually draw together and come into
+collision with an awful crash. There is only one way by which such a
+disaster could be averted. That is by making one of these stars
+revolve around the other just as the earth revolves around the sun, or
+the moon revolves around the earth. Some motion must, therefore, be
+going on in every genuine double star, whether we have been able to
+see that motion or not.
+
+Let us now look at another double star of a different kind. This time
+it is in the constellation of Gemini. The heavenly twins are called
+Castor and Pollux. Of these, Castor is a very beautiful double star,
+consisting of two bright points, a great deal closer together than
+were those in the Great Bear; consequently a better telescope is
+required for the purpose of showing them separately. Castor has been
+watched for many years, and it can be seen that one of these stars is
+slowly revolving around the other; but it takes a very long time,
+amounting to hundreds of years, for a complete circuit to be
+accomplished. This seems very astonishing, but when you remember how
+exceedingly far Castor is, you will perceive that that pair of stars
+which appear so close together that it requires a telescope to show
+them apart must indeed be separated by hundreds of millions of miles.
+Let us try to conceive our own system transformed into a double star.
+If we took our outermost planet--Neptune--and enlarged him a good
+deal, and then heated him sufficiently to make him glow like a sun, he
+would still continue to revolve round our sun at the same distance,
+and thus a double star would be produced. An inhabitant of Castor who
+turned his telescope towards us would be able to see the sun as a
+star. He would not, of course, be able to see the earth, but he might
+see Neptune like another small star close to the sun. If generations
+of astronomers in Castor continued their observations of our system,
+they would find a binary star, of which one component took a century
+and a half to go round the other. Need we then be surprised that when
+we look at Castor we observe movements that seem very slow?
+
+There is often so much diffused light about the bright stars seen in a
+telescope, and so much twinkling in some states of the atmosphere,
+that stars appear to dance about in rather a puzzling fashion,
+especially to one who is not accustomed to astronomical observations.
+I remember hearing how a gentleman once came to visit an observatory.
+The astronomer showed him Castor through a powerful telescope as a
+fine specimen of a double star, and then, by way of improving his
+little lesson, the astronomer mentioned that one of these stars was
+revolving around the other. "Oh, yes," said the visitor, "I saw them
+going round and round in the telescope." He would, however, have had
+to wait for a few centuries with his eye to the instrument before he
+would have been entitled to make this assertion.
+
+Double stars also frequently delight us by giving beautifully
+contrasted colors. I dare say you have often noticed the red and the
+green lights that are used on railways in the signal lamps. Imagine
+one of those red and one of those green lights away far up in the sky
+and placed close together, then you would have some idea of the
+appearance that a colored double star presents, though, perhaps, I
+should add that the hues in the heavenly bodies are not so vividly
+different as are those which our railway people find necessary. There
+is a particularly beautiful double star of this kind in the
+constellation of the Swan. You could make an imitation of it by boring
+two holes, with a red-hot needle, in a piece of card, and then
+covering one of these holes with a small bit of the topaz-colored
+gelatine with which Christmas crackers are made. The other star is to
+be similarly colored with blue gelatine. A slide made on this
+principle placed in the lantern gives a very good representation of
+these two stars on the screen. There are many other colored doubles
+besides this one; and, indeed, it is noteworthy that we hardly ever
+find a blue or a green star by itself in the sky; it is always as a
+member of one of these pairs.
+
+
+How We Find What the Stars are Made of.
+
+Here is a piece of stone. If I wanted to know what it was composed of,
+I should ask a chemist to tell me. He would take it into his
+laboratory, and first crush it into powder, and then, with his test
+tubes, and with the liquids which his bottles contain, and his
+weighing scales, and other apparatus, he would tell all about it;
+there is so much of this, and so much of that, and plenty of this, and
+none at all of that. But now, suppose you ask this chemist to tell you
+what the sun is made of, or one of the stars. Of course, you have not
+a sample of it to give him; how, then, can he possibly find out
+anything about it? Well, he can tell you something, and this is the
+wonderful discovery that I want to explain to you. We now put down the
+gas, and I kindle a brilliant red light. Perhaps some of those whom I
+see before me have occasionally ventured on the somewhat dangerous
+practice of making fire-works. If there is any boy here who has ever
+constructed sky-rockets, and put the little balls into the top which
+are to burn with such vivid colors when the explosion takes place, he
+will know that the substance which tinged that fire red must have been
+strontium. He will recognize it by the color; because strontium gives
+a red light which nothing else will give. Here are some of these
+lightning papers, as they are called; they are very pretty and very
+harmless; and these, too, give brilliant red flashes as I throw them.
+The red tint has, no doubt, been produced by strontium also. You see
+we recognized the substance simply by the color of the light it
+produced when burning.
+
+Perhaps some of you have tried to make a ghost at Christmas by
+dressing up in a sheet, and bearing in your hand a ladle blazing with
+a mixture of common salt and spirits of wine, the effect produced
+being a most ghastly one. Some mammas will hardly thank me for this
+suggestion, unless I add that the ghost must walk about cautiously,
+for otherwise the blazing spirit would be very apt to produce
+conflagrations of a kind more extensive than those intended. However,
+by the kindness of Professor Dewar, I am enabled to show the
+phenomenon on a splendid scale, and also free from all danger. I
+kindle a vivid flame of an intensely yellow color, which I think the
+ladies will unanimously agree is not at all becoming to their
+complexions, while the pretty dresses have lost their variety of
+colors. Here is a nice bouquet, and yet you can hardly distinguish the
+green of the leaves from the brilliant colors of the flowers, except
+by trifling differences of shade. Expose to this light a number of
+pieces of variously colored ribbon, pink and red and green and blue,
+and their beauty is gone; and yet we are told that this yellow is a
+perfectly pure color; in fact, the purest color that can be produced.
+I think we have to be thankful that the light which our good sun sends
+us does not possess purity of that description. There is one substance
+which will produce that yellow light; it is a curious metal called
+sodium--a metal so soft that you can cut it with a knife, and so light
+that it will float on water; while, still more strange, it actually
+takes fire the moment it is dropped on the water. It is only in a
+chemical laboratory that you will be likely to meet with the actual
+metallic sodium, yet in other forms the substance is one of the most
+abundant in nature. Indeed, common salt is nothing but sodium closely
+united with a most poisonous gas, a few respirations of which would
+kill you. But this strange metal and this noxious gas, when united,
+become simply the salt for our eggs at breakfast. This pure yellow
+light, wherever it is seen, either in the flame of spirits of wine
+mixed with salt or in that great blaze at which we have been looking,
+is characteristic of sodium. Wherever you see that particular kind of
+light, you know that sodium must have been present in the body from
+which it came.
+
+We have accordingly learned to recognize two substances, namely,
+strontium and sodium, by the different lights which they give out when
+burning. To these two metals we may add a third. Here is a strip of
+white metallic ribbon. It is called magnesium. It seems like a bit of
+tin at the first glance, but indeed it is a very different substance
+from tin; for, look, when I hold it in the spirit-lamp, the strip of
+metal immediately takes fire, and burns with a white light so dazzling
+that it pales the gas-flames to insignificance. There is no other
+substance which will, when kindled, give that particular kind of light
+which we see from magnesium. I can recommend this little experiment as
+quite suitable for trying at home; you can buy a bit of magnesium
+ribbon for a trifle at the opticians; it cannot explode or do any
+harm, nor will you get into any trouble with the authorities provided
+you hold it when burning over a tray or a newspaper, so as to prevent
+the white ashes from falling on the carpet.
+
+There are, in nature, a number of simple bodies called elements.
+Every one of these, when ignited under suitable conditions, emits a
+light which belongs to it alone, and by which it can be distinguished
+from every other substance. I do not say that we can try the
+experiments in the simple way I have here indicated. Many of the
+materials will yield light which will require to be studied by much
+more elaborate artifices than those which have sufficed for us. But
+you will see that the method affords a means of finding out the actual
+substances present in the sun or in the stars. There is a practical
+difficulty in the fact that each of the heavenly bodies contains a
+number of different elements; so that in the light it sends us the
+hues arising from distinct substances are blended into one beam. The
+first thing to be done is to get some way of splitting up a beam of
+light, so as to discover the components of which it is made. You might
+have a skein of silks of different hues tangled together, and this
+would be like the sunbeam as we receive it in its unsorted condition.
+How shall we untangle the light from the sun or a star? I will show
+you by a simple experiment. Here is a beam from the electric light;
+beautifully white and bright, is it not? It looks so pure and simple,
+but yet that beam is composed of all sorts of colors mingled together,
+in such proportions as to form white light. I take a wedge-shaped
+piece of glass called a prism, and when I introduce it into the course
+of the beam, you see the transformation that has taken place (Fig. 4).
+Instead of the white light you have now all the colors of the
+rainbow--red, orange, yellow, green, blue, indigo, violet, marked by
+their initial letters in the figure. These colors are very beautiful,
+but they are transient, for the moment we take away the prism they
+all unite again to form white light. You see what the prism has done;
+it has bent all the light in passing through it; but it is more
+effective in bending the blue than the red, and consequently the blue
+is carried away much further than the red. Such is the way in which we
+study the composition of a heavenly body. We take a beam of its light,
+we pass it through a prism, and immediately it is separated into its
+components; then we compare what we find with the lights given by the
+different elements, and thus we are enabled to discover the substances
+which exist in the distant object whose light we have examined. I do
+not mean to say that the method is a simple one; all I am endeavoring
+to show is a general outline of the way in which we have discovered
+the materials present in the stars. The instrument that is employed
+for this purpose is called the spectroscope. And perhaps you may
+remember that name by these lines, which I have heard from an
+astronomical friend:--
+
+  "Twinkle, twinkle, little star,
+  Now we find out what you are,
+  When unto the midnight sky,
+  We the spectroscope apply."
+
+[Illustration: FIG. 4. HOW A RAY OF LIGHT IS SPLIT UP.]
+
+I am sure it will interest everybody to know that the elements which
+the stars contain are not altogether different from those of which the
+earth is made. It is true there may be substances in the stars of
+which we know nothing here; but it is certain that many of the most
+common elements on the earth are present in the most distant bodies. I
+shall only mention one, the metal iron. That useful substance has been
+found in some of the stars which lie at almost incalculable distances
+from the earth.
+
+
+The Nebulæ.
+
+In drawing towards the close of these lectures I must say a few words
+about some dim and mysterious objects to which we have not yet
+alluded. They are what are called nebulæ, or little clouds; and in
+one sense they are justly called little, for each of them occupies but
+a very small spot in the sky as compared with that which would be
+filled by an ordinary cloud in our air. The nebulæ are, however,
+objects of the most stupendous proportions. Were our earth and
+thousands of millions of bodies quite as big all put together, they
+would not be nearly so great as one of these nebulæ. Astronomers
+reckon up the various nebulæ by thousands, but I must add that most of
+them are apparently faint and uninteresting. A nebula is sometimes
+liable to be mistaken for a comet. The comet is, as I have already
+explained, at once distinguished by the fact that it is moving and
+changing its appearance from hour to hour, while scores of years
+elapse without changes in the aspect or position of a nebula. The most
+powerful telescopes are employed in observing these faint objects. I
+take this opportunity of showing a picture of an instrument suitable
+for such observations. It is the great reflector of the Paris
+Observatory (Fig. 5).
+
+[Illustration: FIG. 5. A GREAT REFLECTING TELESCOPE.]
+
+[Illustration: FIG. 6. THE RING NEBULA IN LYRA, UNDER DIFFERENT
+TELESCOPIC POWERS.]
+
+There are such multitudes of nebulæ that I can only show a few of the
+more remarkable kinds. In Fig. 6 will be seen pictures of a curious
+object in the constellation of Lyra seen under different telescopic
+powers. This is a gigantic ring of luminous gas. To judge of the size
+of this ring let us suppose that a railway were laid across it, and
+the train you entered at one side was not to stop until it reached the
+other side, how long do you think this journey would require? I
+recollect some time ago a picture in _Punch_ which showed a train
+about to start from London to Brighton, and the guard walking up and
+down announcing to the passengers the alarming fact that "this train
+stops nowhere." An old gentleman was seen vainly gesticulating out of
+the window and imploring to be let out ere the frightful journey was
+commenced. In the nebular railway the passengers would almost require
+such a warning.
+
+Let the train start at a speed of a mile a minute, you would think,
+surely, that it must soon cross the ring. But the minutes pass, an
+hour has elapsed; so the distance must be sixty miles at all events.
+The hours creep on into days, the days advance into years, and still
+the train goes on. The years would lengthen out into centuries, and
+even when the train had been rushing on for a thousand years with an
+unabated speed of a mile a minute, the journey would certainly not
+have been completed. Nor do I venture to say what ages must elapse ere
+the terminus at the other side of the ring nebula would be reached.
+
+A cluster of stars viewed in a small telescope will often seem like a
+nebula, for the rays of the stars become blended. A powerful telescope
+will, however, dispel the illusion and reveal the separate stars. It
+was, therefore, thought that all the nebulæ might be merely clusters
+so exceedingly remote that our mightiest instruments failed to resolve
+them into stars. But this is now known not to be the case. Many of
+these objects are really masses of glowing gas; such are, for
+instance, the ring nebulæ, of which I have just spoken, and the form
+of which I can simulate by a pretty experiment.
+
+We take a large box with a round hole cut in one face, and a canvas
+back at the opposite side. I first fill this box with smoke, and there
+are different ways of doing so. Burning brown paper does not answer
+well, because the supply of smoke is too irregular and the paper
+itself is apt to blaze. A little bit of phosphorus set on fire yields
+copious smoke, but it would be apt to make people cough, and, besides,
+phosphorus is a dangerous thing to handle incautiously, and I do not
+want to suggest anything which might be productive of disaster if the
+experiment was repeated at home. A little wisp of hay, slightly damped
+and lighted, will safely yield a sufficient supply, and you need not
+have an elaborate box like this; any kind of old packing-case, or even
+a bandbox with a duster stretched across its open top and a round hole
+cut in the bottom, will answer capitally. While I have been speaking,
+my assistant has kindly filled this box with smoke, and in order to
+have a sufficient supply, and one which shall be as little
+disagreeable as possible, he has mixed together the fumes of
+hydrochloric acid and ammonia from two retorts shown in Fig. 7. A
+still simpler way of doing the same thing is to put a little common
+salt in a saucer and pour over it a little oil of vitriol; this is put
+into the box, and over the floor of the box common smelling-salts is
+to be scattered. You see there are dense volumes of white smoke
+escaping from every corner of the box. I uncover the opening and give
+a push to the canvas, and you see a beautiful ring flying across the
+room; another ring and another follows. If you were near enough to
+feel the ring, you would experience a little puff of wind; I can show
+this by blowing out a candle which is at the other end of the table.
+These rings are made by the air which goes into a sort of eddy as it
+passes through the hole. All the smoke does is to render the air
+visible. The smoke-ring is indeed quite elastic. If we send a second
+ring hurriedly after the first, we can produce a collision, and you
+see each of the two rings remains unbroken, though both are quivering
+from the effects of the blow. They are beautifully shown along the
+beam of the electric lamp, or, better still, along a sunbeam.
+
+[Illustration: FIG. 7. HOW TO MAKE THE SMOKE RINGS.]
+
+We can make many experiments with smoke-rings. Here, for instance, I
+take an empty box, so far as smoke is concerned, but air-rings can be
+driven forth from it, though you cannot see them, but you can feel
+them even at the other side of the room, and they will, as you see,
+blow out a candle. I can also shoot invisible air-rings at a column of
+smoke, and when the missile strikes the smoke it produces a little
+commotion and emerges on the other side, carrying with it enough of
+the smoke to render itself visible, while the solid black looking ring
+of air is seen in the interior. Still more striking is another way of
+producing these rings, for I charge this box with ammonia, and the
+rings from it you cannot see. There is a column of the vapor of
+hydrochloric acid, that also you cannot see; but when the visible ring
+enters the invisible column, then a sudden union takes place between
+the vapor of the ammonia and the vapor of the hydrochloric acid; the
+result is a solid white substance in extremely fine dust which renders
+the ring instantly visible.
+
+
+What the Nebulæ are made of.
+
+There is a fundamental difference between the illumination of these
+little rings that I have shown you and the great rings in the heavens.
+I had to illuminate our smoke with the help of the electric light,
+for, unless I had done so, you would not have been able to see them.
+This white substance formed by the union of ammonia and hydrochloric
+acid has, of course, no more light of its own than a piece of chalk;
+it requires other light falling upon it to make it visible. Were the
+ring nebula in Lyra composed of this material, we could not see it.
+The sunlight which illuminates the planets might, of course, light up
+such an object as the ring, if it wrere comparatively near us; but
+Lyra is at such a stupendous distance that any light which the sun
+could send out there would be just as feeble as the light we receive
+from a fixed star. Should we be able to show our smoke-rings, for
+instance, if, instead of having the electric light, I merely cut a
+hole in the ceiling and allowed the feeble twinkle of a star in the
+Great Bear to shine through? In a similar way the sunbeams would be
+utterly powerless to effect any illumination of objects in these
+stellar distances. If the sun were to be extinguished altogether, the
+calamity would no doubt be a very dire one so far as we are concerned,
+but the effect on the other celestial bodies (moon and planets
+excepted) would be of the slightest possible description. All the
+stars of heaven would continue to shine as before. Not a point in one
+of the constellations wrould be altered, not a variation in the
+brightness, not a change in the hue of any star could be noticed. The
+thousands of nebulæ and clusters would be absolutely unaltered; in
+fact, the total extinction of the sun would be hardly remarked in the
+newspapers published in the Pleiades or in Orion. There might possibly
+be a little line somewhere in an odd corner to the effect "Mr.
+So-and-So, our well-known astronomer, has noticed that a tiny star,
+inconspicuous to the eye, and absolutely of no importance whatever,
+has now become invisible."
+
+If, therefore, it be not the sun which lights up this nebula, where
+else can be the source of its illumination? There can be no other star
+in the neighborhood adequate to the purpose, for, of course, such an
+object would be brilliant to us if it were large enough and bright
+enough to impart sufficient illumination to the nebula. It would be
+absurd to say that you could see a man's face by the light of a candle
+while the candle itself was too faint or too distant to be visible.
+The actual facts are, of course, the other way; the candle might be
+visible, when it was impossible to discern the face which it lighted.
+
+Hence we learn that the ring nebula must shine by some light of its
+own, and now we have to consider how it can be possible for such
+material to be self-luminous. The light of a nebula does not seem to
+be like flame; it can, perhaps, be better represented by the pretty
+electrical experiment with Geissler's tubes. These are glass vessels
+of various shapes, and they are all very nearly empty, as you will
+understand when I tell you the way in which they have been prepared. A
+little gas was allowed into each tube, and then almost all the gas was
+taken out again, so that only a mere trace was left. I pass a current
+of electricity through these tubes, and now you see they are glowing
+with beautiful colors. The different gases give out lights of
+different hues, and the optician has exerted his skill so as to make
+the effect as beautiful as possible. The electricity, in passing
+through these tubes, heats the gas which they contain, and makes it
+glow; and just as this gas can, when heated sufficiently, give out
+light, so does the great nebula, which is a mass of gas poised in
+space, become visible in virtue of the heat which it contains.
+
+We are not left quite in doubt as to the constitution of these gaseous
+nebulæ, for we can submit their light to the prism in the way I
+explained when we were speaking of the stars. Distant though that ring
+in Lyra may be, it is interesting to learn that the ingredients from
+which it is made are not entirely different from substances we know on
+our earth. The water in this glass, and every drop of water, is formed
+by the union of two gases, of which one is hydrogen. This is an
+extremely light material, as you see by a little balloon which ascends
+so prettily when filled with it. Hydrogen also burns very readily,
+though the flame is almost invisible. When I blow a jet of oxygen
+through the hydrogen, I produce a little flame with a very intense
+heat. For instance, I hold a steel pen in the flame, and it glows and
+sputters, and falls down in white-hot drops. It is needless to say
+that, as a constituent of water, hydrogen is one of the most important
+elements on this earth. It is, therefore, of interest to learn that
+hydrogen in some form or other is a constituent of the most distant
+objects in space that the telescope has revealed.
+
+
+Photographing the Nebulæ.
+
+[Illustration: FIG. 8. THE PLEIADES.]
+
+Of late years we have learned a great deal about nebulæ, by the help
+which photography has given to us. Look at this group of stars which
+constitutes that beautiful little configuration known as the Pleiades
+(Fig. 8). It looks like a miniature representation of the Great Bear;
+in fact, it would be far more appropriate to call the Pleiades the
+Little Bear than to apply that title to another quite different
+constellation, as has unfortunately been done. The Pleiades form a
+group containing six or seven stars visible to the ordinary eye,
+though persons endowed with exceptionally good vision can usually see
+a few more. In an opera-glass the Pleiades becomes a beautiful
+spectacle, though in a large telescope the stars appear too far apart
+to make a really effective cluster. When Mr. Roberts took a photograph
+of the Pleiades he placed a highly sensitive plate in his telescope,
+and on that plate the Pleiades engraved their picture with their own
+light. He left the plate exposed for hours, and on developing it not
+only were the stars seen, but there were also patches of faint light
+due to the presence of nebulæ. It could not be said that the objects
+on the plate were fallacious, for another photograph was taken, when
+the same appearances were reproduced.
+
+When we look at that pretty group of stars which has attracted
+admiration during all time, we are to think that some of those stars
+are merely the bright points in a vast nebula, invisible to our
+unaided eyes or even to our mighty telescopes, though capable of
+recording its trace on the photographic plate. Does not this give us a
+greatly increased notion of the extent of the universe, when we
+reflect that by photography we are enabled to see much which the
+mightiest of telescopes had previously failed to disclose?
+
+Of all the nebulæ, numbering some thousands, there is but a single one
+which can be seen without a telescope. It is in the constellation of
+Andromeda, and on a clear dark night can just be seen with the unaided
+eye as a faint stain of light on the sky. It has happened before now
+that persons noticing this nebula for the first time have thought they
+had discovered a comet. I would like you to try and find out this
+object for yourselves.
+
+If you look at it with an opera-glass it appears to be distinctly
+elongated. You can see more of its structure when you view it in
+larger instruments, but its nature was never made clear until some
+beautiful photographs were taken by Mr. Roberts (Fig. 9).
+Unfortunately, the nebula in Andromeda has not been placed in the best
+position for its portrait from our point of view. It seems as if it
+were a rather flat-shaped object, turned nearly edgewise towards us.
+To look at the pattern on a plate, you would naturally hold the plate
+so as to be able to look at it squarely. The pattern would not be seen
+well if the plate were so tilted that its edge was turned towards you.
+That seems to be nearly the way in which we are forced to view the
+nebula in Andromeda. We can trace in the photograph some divisions
+extending entirely round the nebula, showing that it seems to be
+formed of a series of rings; and there are some outlying portions
+which form part of the same system. Truly this is a marvellous object.
+It is impossible for us to form any conception of the true dimensions
+of this gigantic nebula; it is so far off that we have never yet been
+able to determine its distance. Indeed, I may take this opportunity of
+remarking that no astronomer has yet succeeded in ascertaining the
+distance of any nebula. Everything, however, points to the conclusion
+that they are at least as far as the stars.
+
+[Illustration: FIG. 9. THE GREAT NEBULA IN ANDROMEDA.]
+
+It is almost impossible to apply the methods which we use in finding
+the distance of a star to the discovery of the distance of the
+nebulæ. These flimsy bodies are usually too ill-defined to admit of
+being measured with the precision and delicacy required for the
+determination of distance. The measurements necessary for this purpose
+can only be made from one star-like point to another similar point. If
+we could choose a star in the nebula and determine its distance, then
+of course, we have the distance of the nebula itself; but the
+difficulty is that we have, in general, no means of knowing whether
+the star does actually lie in the object. It may, for anything we can
+tell, lie billions of miles nearer to us, or billions of miles further
+off, and by merely happening to lie in the line of sight, appear to
+glimmer in the nebula itself.
+
+If we have any assurance that the star is surrounded by a mass of this
+glowing vapor, then it may be possible to measure that nebula's
+distance. It will occasionally happen that grounds can be found for
+believing that a star which appears to be in the glowing gas does
+veritably lie therein, and is not merely seen in the same direction.
+There are hundreds of stars visible in a good drawing or a good
+photograph of the famous object in Andromeda, and doubtless large
+numbers of these are merely stars which happen to lie in the same line
+of sight. The peculiar circumstances attending the history of one star
+seem, however, to warrant us in making the assumption that it was
+certainly in the nebula. The history of this star is a remarkable one.
+It suddenly kindled from invisibility into brilliancy. How is a change
+so rapid in the lustre of a star to be accounted for? In a few days
+its brightness had undergone an extraordinary increase. Of course,
+this does not tell us for certain that the star lay in the glowing
+gas; but the most rational explanation that I have heard offered of
+this occurrence is that due, I believe, to my friend Mr. Monck. He has
+suggested that the sudden outbreak in brilliancy might be accounted
+for on the same principles as those by which we explain the ignition
+of meteors in our atmosphere. If a dark star, moving along with
+terrific speed through space, were suddenly to plunge into a dense
+region of the nebula, heat and light must be evolved in sufficient
+abundance to transform the star into a brilliant object. If,
+therefore, we knew the distance of this star at the time it was in
+Andromeda, we should, of course, learn the distance of that
+interesting object. This has been attempted, and it has thus been
+proved that the Great Nebula must be very much further from us than is
+that star of whose distance I attempted some time ago to give you a
+notion.
+
+We thus realize the enormous size of the Great Nebula. It appears that
+if, on a map of this object, we were to lay down, accurately to scale,
+a map of the solar system, putting the sun in the centre and all the
+planets around their true proportions out to the boundary traced by
+Neptune, this area, vast though it is, would be a mere speck on the
+drawing of the object. Our system would have to be enormously bigger
+before it sufficed to cover anything like the area of the sky included
+in one of these great objects. Here is a sketch of a nebula, Fig. 10,
+and near I have marked a dot, which is to indicate our solar system.
+We may feel confident that the Great Nebula is at the very least as
+mighty as this proportion would indicate.
+
+[Illustration: FIG. 10. THE SOLAR SYSTEM AS COMPARED WITH A GREAT
+NEBULA.]
+
+
+
+
+RAIN AND SNOW
+
+(FROM THE FORMS OF WATER.)
+
+BY JOHN TYNDALL.
+
+
+Oceanic Distillation.
+
+[Illustration: SNOW CRYSTALS.]
+
+At the equator, and within certain limits north and south of it, the
+sun at certain periods of the year is directly overhead at noon. These
+limits are called the Tropics of Cancer and of Capricorn. Upon the
+belt comprised between these two circles the sun's rays fall with
+their mightiest power; for here they shoot directly downwards, and
+heat both earth and sea more than when they strike slantingly.
+
+When the vertical sunbeams strike the land they heat it, and the air
+in contact with the hot soil becomes heated in turn. But when heated
+the air expands, and when it expands it becomes lighter. This lighter
+air rises, like wood plunged into water, through the heavier air
+overhead.
+
+When the sunbeams fall upon the sea the water is warmed, though not so
+much as the land. The warmed water expands, becomes thereby lighter,
+and therefore continues to float upon the top. This upper layer of
+water warms to some extent the air in contact with it, but it also
+sends up a quantity of aqueous vapor, which being far lighter than
+air, helps the latter to rise. Thus both from the land and from the
+sea we have ascending currents established by the action of the sun.
+
+When they reach a certain elevation in the atmosphere, these currents
+divide and flow, part towards the north and part towards the south;
+while from the north and the south a flow of heavier and colder air
+sets in to supply the place of the ascending warm air.
+
+Incessant circulation is thus established in the atmosphere. The
+equatorial air and vapor flow above towards the north and south poles,
+while the polar air flows below towards the equator. The two currents
+of air thus established are called the upper and the lower trade
+winds.
+
+But before the air returns from the poles great changes have occurred.
+For the air as it quitted the equatorial regions was laden with
+aqueous vapor, which could not subsist in the cold polar regions. It
+is there precipitated, falling sometimes as rain, or more commonly as
+snow. The land near the pole is covered with this snow, which gives
+birth to vast glaciers.
+
+It is necessary that you should have a perfectly clear view of this
+process, for great mistakes have been made regarding the manner in
+which glaciers are related to the heat of the sun.
+
+It was supposed that if the sun's heat were diminished, greater
+glaciers than those now existing would be produced. But the lessening
+of the sun's heat would infallibly diminish the quantity of aqueous
+vapor, and thus cut off the glaciers at their source. A brief
+illustration will complete your knowledge here.
+
+In the process of ordinary distillation, the liquid to be distilled is
+heated and converted into vapor in one vessel, and chilled and
+reconverted into liquid in another. What has just been stated renders
+it plain that the earth and its atmosphere constitute a vast
+distilling apparatus in which the equatorial ocean plays the part of
+the boiler, and the chill regions of the poles the part of the
+condenser. In this process of distillation _heat_ plays quite as
+necessary a part as _cold_, and before Bishop Heber could speak of
+"Greenland's icy mountains," the equatorial ocean had to be warmed by
+the sun. We shall have more to say upon this question afterwards.
+
+The heating of the tropical air by the sun is _indirect_. The solar
+beams have scarcely any power to heat the air through which they pass;
+but they heat the land and ocean, and these communicate their heat to
+the air in contact with them. The air and vapor start upwards charged
+with the heat thus communicated.
+
+
+Tropical Rains.
+
+But long before the air and vapor from the equator reach the poles,
+precipitation occurs. Wherever a humid warm wind mixes with a cold dry
+one, rain falls. Indeed the heaviest rains occur at those places where
+the sun is vertically overhead. We must enquire a little more closely
+into their origin.
+
+Fill a bladder about two-thirds full of air at the sea level, and take
+it to the summit of Mount Blanc. As you ascend, the bladder becomes
+more and more distended; at the top of the mountain it is fully
+distended, and has evidently to bear a pressure from within. Returning
+to the sea level you find that the tightness disappears, the bladder
+finally appearing as flaccid as at first.
+
+The reason is plain. At the sea level the air within the bladder has
+to bear the pressure of the whole atmosphere, being thereby squeezed
+into a comparatively small volume. In ascending the mountain, you
+leave more and more of the atmosphere behind; the pressure becomes
+less and less, and by its expansive force the air within the bladder
+swells as the outside pressure is diminished. At the top of the
+mountain the expansion is quite sufficient to render the bladder
+tight, the pressure within being then actually greater than the
+pressure without. By means of an air-pump we can show the expansion of
+a balloon partly filled with air, when the external pressure has been
+in part removed.
+
+But why do I dwell upon this? Simply to make plain to you that the
+_unconfined air_, heated at the earth's surface, and ascending by its
+lightness, must expand more and more the higher it rises in the
+atmosphere.
+
+And now I have to introduce to you a new fact, towards the statement
+of which I have been working for some time. It is this: _The ascending
+air is chilled by its expansion_. Indeed this chilling is one source
+of the coldness of the higher atmospheric regions. And now fix your
+eye upon those mixed currents of air and aqueous vapor which rise from
+the warm tropical ocean. They start with plenty of heat to preserve
+the vapor as vapor; but as they rise they come into regions already
+chilled, and they are still further chilled by their own expansion.
+The consequence might be foreseen. The load of vapor is in great part
+precipitated, dense clouds are formed, their particles coalesce to
+rain-drops, which descend daily in gushes so profuse that the word
+"torrential" is used to express the copiousness of the rainfall. I
+could show you this chilling by expansion, and also the consequent
+precipitation of clouds.
+
+Thus long before the air from the equator reaches the poles its vapor
+is in great part removed from it, having redescended to the earth as
+rain. Still a good quantity of the vapor is carried forward, which
+yields hail, rain, and snow in northern and southern lands.
+
+
+Mountain Condensers.
+
+To complete our view of the process of atmospheric precipitation we
+must take into account the action of mountains. Imagine a south-west
+wind blowing across the Atlantic towards Ireland. In its passage it
+charges itself with aqueous vapor. In the south of Ireland it
+encounters the mountains of Kerry: the highest of these is
+Magillicuddy's Reeks, near Killarney. Now the lowest stratum of this
+Atlantic wind is that which is most fully charged with vapor. When it
+encounters the base of the Kerry Mountains it is tilted up and flows
+bodily over them. Its load of vapor is therefore carried to a height,
+it expands on reaching the height, it is chilled in consequence of
+the expansion, and comes down in copious showers of rain. From this,
+in fact, arises the luxuriant vegetation of Killarney; to this,
+indeed, the lakes owe their water supply. The cold crests of the
+mountains also aid in the work of condensation.
+
+Note the consequence. There is a town called Cahirciveen to the
+south-west of Magillicuddy's Reeks, at which observations of the
+rainfall have been made, and a good distance farther to the
+north-east, right in the course of the south-west wind there is
+another town, called Portarlington, at which observations of rainfall
+have also been made. But before the wind reaches the latter station it
+has passed over the mountains of Kerry and left a great portion of its
+moisture behind it. What is the result? At Cahirciveen, as shown by
+Dr. Lloyd, the rainfall amounts to fifty-nine inches in a year, while
+at Portarlington it is only twenty-one inches.
+
+Again, you may sometimes descend from the Alps when the fall of rain
+and snow is heavy and incessant, into Italy, and find the sky over the
+plains of Lombardy blue and cloudless, the wind at the same time
+_blowing over the plain towards the Alps_. Below the wind is hot
+enough to keep its vapor in a perfectly transparent state; but it
+meets the mountains, is tilted up, expanded, and chilled. The cold of
+the higher summits also helps the chill. The consequence is that the
+vapor is precipitated as rain or snow, thus producing bad weather upon
+the heights, while the plains below, flooded with the same air, enjoy
+the aspect of the unclouded summer sun. Clouds blowing _from_ the
+Alps are also sometimes dissolved over the plains of Lombardy.
+
+In connection with the formation of clouds by mountains, one
+particularly instructive effect may be here noticed. You frequently
+see a streamer of cloud many hundred yards in length drawn out from an
+Alpine peak. Its steadiness appears perfect, though a strong wind may
+be blowing at the same time over the mountain head. Why is the cloud
+not blown away? It _is_ blown away; its permanence is only apparent.
+At one end it is incessantly dissolved; at the other end it is
+incessantly renewed: supply and consumption being thus equalized, the
+cloud appears as changeless as the mountain to which it seems to
+cling. When the red sun of the evening shines upon these
+cloud-streamers they resemble vast torches with their flames blown
+through the air.
+
+Architecture of Snow.
+
+We now resemble persons who have climbed a difficult peak, and thereby
+earned the enjoyment of a wide prospect. Having made ourselves masters
+of the conditions necessary to the production of mountain snow, we are
+able to take a comprehensive and intelligent view of the phenomena of
+glaciers.
+
+[Illustration: SNOW CRYSTALS.]
+
+A few words are still necessary as to the formation of snow. The
+molecules and atoms of all substances, when allowed free play, build
+themselves into definite and, for the most part, beautiful forms
+called crystals. Iron, copper, gold, silver, lead, sulphur, when
+melted and permitted to cool gradually, all show this crystallizing
+power. The metal bismuth shows it in a particularly striking manner,
+and when properly fused and solidified, self-built crystals of great
+size and beauty are formed of this metal.
+
+[Illustration: SNOW-STAR.]
+
+[Illustration: SNOW-STAR.]
+
+If you dissolve salt-petre in water, and allow the solution to
+evaporate slowly, you may obtain large crystals, for no portion of the
+salt is converted into vapor. The water of our atmosphere is fresh
+though it is derived from the salt sea. Sugar dissolved in water, and
+permitted to evaporate, yields crystals of sugar-candy. Alum readily
+crystallizes in the same way. Flints dissolved, as they sometimes are
+in nature, and permitted to crystallize, yield the prisms and pyramids
+of rock crystal. Chalk dissolved and crystallized yields Iceland spar.
+The diamond is crystallized carbon. All our precious stones, the
+ruby, sapphire, beryl, topaz, emerald, are all examples of this
+crystallizing power.
+
+[Illustration: SNOW-STAR.]
+
+You have heard of the force of gravitation, and you know that it
+consists of an attraction of every particle of matter for every other
+particle. You know that planets and moons are held in their orbits by
+this attraction. But gravitation is a very simple affair compared to
+the force, or rather forces, of crystallization. For here the ultimate
+particles of matter, inconceivably small as they are, show themselves
+possessed of attractive and repellent poles, by the mutual action of
+which the shape and structure of the crystal are determined. In the
+solid condition the attracting poles are rigidly locked together; but
+if sufficient heat be applied the bond of union is dissolved, and in
+the state of fusion the poles are pushed so far asunder as to be
+practically out of each other's range. The natural tendency of the
+molecules to build themselves together is thus neutralized.
+
+This is the case with water, which as a liquid is to all appearance
+formless. When sufficiently cooled the molecules are brought within
+the play of the crystallizing force, and they then arrange themselves
+in forms of indescribable beauty. When snow is produced in calm air,
+the icy particles build themselves into beautiful stellar shapes, each
+star possessing six rays. There is no deviation from this type, though
+in other respects the appearances of the snow-stars are infinitely
+various. In the polar regions these exquisite forms were observed by
+Dr. Scoresby, who gave numerous drawings of them. I have observed them
+in mid-winter filling the air, and loading the slopes of the Alps. But
+in England they are also to be seen, and no words of mine could convey
+so vivid an impression of their beauty as the annexed drawings of a
+few of them, executed at Greenwich by Mr. Glaisher.
+
+[Illustration: SNOW-STAR.]
+
+It is worth pausing to think what wonderful work is going on in the
+atmosphere during the formation and descent of every snow-shower; what
+building power is brought into play! and how imperfect seem the
+productions of human minds and hands when compared with those formed
+by the blind forces of nature!
+
+But who ventures to call the forces of nature blind? In reality, when
+we speak thus we are describing our own condition. The blindness is
+ours; and what we really ought to say, and to confess, is that our
+powers are absolutely unable to comprehend either the origin or the
+end of the operations of nature.
+
+But while we thus acknowledge our limits, there is also reason for
+wonder at the extent to which science has mastered the system of
+nature. From age to age, and from generation to generation, fact has
+been added to fact, and law to law, the true method and order of the
+Universe being thereby more and more revealed. In doing this science
+has encountered and overthrown various forms of superstition and
+deceit, of credulity and imposture. But the world continually produces
+weak persons and wicked persons; and as long as they continue to exist
+side by side, as they do in this our day, very debasing beliefs will
+also continue to infest the world.
+
+
+Atomic Poles.
+
+"What did I mean when, a few moments ago I spoke of attracting and
+repellent poles?" Let me try to answer this question. You know that
+astronomers and geographers speak of the earth's poles, and you have
+also heard of magnetic poles, the poles of a magnet being the points
+at which the attraction and repulsion of the magnet are as it were
+concentrated.
+
+Every magnet possesses two such poles; and if iron filings be
+scattered over a magnet, each particle becomes also endowed with two
+poles. Suppose such particles devoid of weight and floating in our
+atmosphere, what must occur when they come near each other? Manifestly
+the repellent poles will retreat from each other, while the attractive
+poles will approach and finally lock themselves together. And
+supposing the particles, instead of a single pair, to possess several
+pairs of poles arranged at definite points over their surfaces; you
+can then picture them, in obedience to their mutual attractions and
+repulsions, building themselves together to form masses of definite
+shape and structure.
+
+Imagine the molecules of water in calm cold air to be gifted with
+poles of this description, which compel the particles to lay
+themselves together in a definite order, and you have before your
+mind's eye the unseen architecture which finally produces the visible
+and beautiful crystals of the snow. Thus our first notions and
+conceptions of poles are obtained from the sight of our eyes in
+looking at the effects of magnetism; and we then transfer these
+notions and conceptions to particles which no eye has ever seen. The
+power by which we thus picture to ourselves effects beyond the range
+of the senses is what philosophers call the Imagination, and in the
+effort of the mind to seize upon the unseen architecture of crystals,
+we have an example of the "scientific use" of this faculty. Without
+imagination we might have _critical_ power, but not _creative_ power
+in science.
+
+
+Architecture of Lake Ice.
+
+We have thus made ourselves acquainted with the beautiful snow-flowers
+self-constructed by the molecules of water in calm, cold air. Do the
+molecules show this architectural power when ordinary water is frozen?
+What, for example, is the structure of the ice over which we skate in
+winter? Quite as wonderful as the flowers of the snow. The observation
+is rare, if not new, but I have seen in water slowly freezing
+six-rayed ice-stars formed, and floating free on the surface. A
+six-rayed star, moreover, is typical of the construction of all our
+lake ice. It is built up of such forms wonderfully interlaced.
+
+Take a slab of lake ice and place it in the path of a concentrated
+sunbeam. Watch the track of the beam through the ice. Part of the beam
+is stopped, part of it goes through; the former produces internal
+liquefaction, the latter has no effect whatever upon the ice. But the
+liquefaction is not uniformly diffused. From separate spots of the ice
+little shining points are seen to sparkle forth. Every one of those
+points is surrounded by a beautiful liquid flower with six petals.
+
+Ice and water are so optically alike that unless the light fall
+properly upon these flowers you cannot see them. But what is the
+central spot? A vacuum. Ice swims on water because, bulk for bulk, it
+is lighter than water; so that when ice is melted it shrinks in size.
+Can the liquid flowers then occupy the whole space of the ice melted?
+Plainly no. A little empty space is formed with the flowers, and this
+space, or rather its surface, shines in the sun with the lustre of
+burnished silver.
+
+In all cases the flowers are formed parallel to the surface of
+freezing. They are formed when the sun shines upon the ice of every
+lake; sometimes in myriads, and so small as to require a magnifying
+glass to see them. They are always attainable, but their beauty is
+often marred by internal defects of the ice. Every one portion of the
+same piece of ice may show them exquisitely, while a second portion
+shows them imperfectly.
+
+Annexed is a very imperfect sketch of these beautiful figures.
+
+Here we have a reversal of the process of crystallization. The
+searching solar beam is delicate enough to take the molecules down
+without deranging the order of their architecture. Try the experiment
+for yourself with a pocket-lens on a sunny day. You will not find the
+flowers confused; they all lie parallel to the surface of freezing. In
+this exquisite way every bit of the ice over which our skaters glide
+in winter is put together.
+
+I said that a portion of the sunbeam was stopped by the ice and
+liquefied it. What is this portion? The dark heat of the sun. The
+great body of the light waves and even a portion of the dark ones,
+pass through the ice without losing any of their heating power. When
+properly concentrated on combustible bodies, even after having passed
+through the ice, their burning power becomes manifest.
+
+[Illustration: LIQUID FLOWERS IN LAKE ICE.]
+
+And the ice itself may be employed to concentrate them. With an
+ice-lens in the polar regions Dr. Scoresby has often concentrated the
+sun's rays so as to make them burn wood, fire gunpowder, and melt
+lead; thus proving that the heating power is retained by the rays,
+even after they have passed through so cold a substance.
+
+By rendering the rays of the electric lamp parallel, and then sending
+them through a lens of ice, we obtain all the effects which Dr.
+Scoresby obtained with the rays of the sun.
+
+[Illustration]
+
+
+
+
+THE ORGANIC WORLD
+
+(FROM THE ELEMENTS OF SCIENCE.)
+
+BY ST. GEORGE MIVART F.R.S.
+
+
+The number of all the various kinds of living creatures is so enormous
+that it would be impossible to study them profitably, were they not
+classified in an orderly manner. Therefore the whole mass has been
+divided, in the first place, into two supreme groups, fancifully
+termed kingdoms--the "animal kingdom" and the "vegetal kingdom." Each
+of these is subdivided into an orderly series of subordinate groups,
+successively contained one within the other, and named sub-kingdoms,
+classes, orders, families, genera and species. The lowest group but
+one is the "genus," which contains one or more different kinds termed
+"species," as e.g., the species "wood anemone" and the species "blue
+titmouse." The lowest group of all--a species--may be said to consist
+of individuals which differ from each other only by trifling
+characters, such as characters due to difference of sex, while their
+peculiar organization is faithfully reproduced by generation as a
+whole, though small individual differences exist in all cases.
+
+The vegetal, or vegetable, kingdom, consists of the great mass of
+flowering plants, many of which, however, have such inconspicuous
+flowers that they are mistakenly regarded as flowerless, as is often
+the case with the grasses, the pines, and the yews. Another mass, or
+sub-kingdom, of plants consists of the really flowerless plants, such
+as the ferns, horsetails (Fig. 1), lycopods, and mosses. Sea and
+fresh-water weeds (_algæ_), and mushrooms, or "moulds," of all kinds
+(_fungi_), amongst which are the now famous "bacteria," constitute a
+third and lowest set of plants.
+
+[Illustration: FIG. 1. HORSE-TAIL (_Equisetum drummondii_).]
+
+The animal kingdom consists, first, of a sub-kingdom of animals which
+possess a spinal column, or backbone, and which are known as
+vertebrate animals. Such are all beasts, birds, reptiles, and fishes.
+There are also a variety of remotely allied marine organisms known as
+tunicates, sea-squirts, or ascidians (Fig. 2). There is, further, an
+immense group of arthropods, consisting of all insects, crab-like
+creatures, hundred-legs and their allies, with spiders, scorpions,
+tics and mites. We have also the sub-kingdom of shell-fish or
+molluscs, including cuttle-fishes, snails, whelks, limpets, the
+oyster, and a multitude of allied forms. A multitudinous sub-kingdom of
+worms also exists, as well as another of star-fishes and their
+congeners. There is yet another of zoophytes, or polyps, and another
+of sponges, and, finally, we have a sub-kingdom of minute creatures,
+or animalculæ, of very varied forms, which may make up the sub-kingdom
+of _Protozoa_, consisting of animals which are mostly unicellular.
+
+[Illustration: FIG. 2. A TUNICATE (_Ascidia_).]
+
+Multitudinous and varied as are the creatures which compose this
+immense organic world, they nevertheless exhibit a very remarkable
+uniformity of composition in their essential structure. Every living
+creature from a man to a mushroom, or even to the smallest animalcule
+or unicellular plant is always partly fluid, but never entirely so.
+Every living creature also consists in part (and that part is the most
+active living part) of a soft, viscid, transparent, colorless
+substance, termed protoplasm, which can be resolved into the four
+elements, oxygen, hydrogen, nitrogen and carbon. Besides these four
+elements, living organisms commonly contain sulphur, phosphorus,
+chlorine, potassium, sodium, calcium, magnesium and iron.
+
+In the fact that living creatures always consist of the four elements,
+oxygen, hydrogen, nitrogen and carbon, we have a fundamental character
+whereby the organic and inorganic (or non-living) worlds are to be
+distinguished, for as we have seen, inorganic bodies, instead of being
+thus uniformly constituted, may consist of the most diverse elements
+and sometimes of but two or even of only one.
+
+Again, many minerals, such as crystals, are bounded by plain surfaces,
+and, with very few exceptions (spathic and hematite iron and dolomite
+are such exceptions) none are bounded by curved lines and surfaces,
+while living organisms are bounded by such lines and surfaces.
+
+Yet, again, if a crystal be cut through, its internal structure will
+be seen to be similar throughout. But if the body of any living
+creature be divided, it will, at the very least, be seen to consist of
+a variety of minute distinct particles, called "granules," variously
+distributed throughout its interior.
+
+All organisms consist either--as do the simplest, mostly microscopic,
+plants and animals--of a single minute mass of protoplasm, or of a
+few, or of many, or of an enormous aggregation of such before-mentioned
+particles, each of which is one of those bodies named a "cell" (Fig.
+3). Cells may, or may not, be enclosed in an investing coat or
+"cell-wall." Every cell generally contains within it a denser,
+normally spheroidal, body known as the nucleus.
+
+Now protoplasm is a very unstable substance--as we have seen many
+substances are whereof nitrogen is a component part--and it possesses
+active properties which are not present in the non-living, or
+inorganic world. In the latter, differences of temperature will
+produce motion in the shape of "currents," as we have seen with
+respect to masses of air and water. But in a portion of protoplasm,
+an internal circulation of currents in definite lines will establish
+itself from other causes.
+
+Inorganic bodies, as we have seen, will expand with heat, as they may
+also do from imbibing moisture; but living protoplasm has an
+apparently spontaneous power of contraction and expansion under
+certain external conditions which do not occasion such movements in
+inorganic matter.
+
+[Illustration: FIG. 3. CELL FROM A SALAMANDER. _n_, nucleus; _n'_,
+nucleolus embedded in the network of chromatin threads; _k_, network
+of the cell external to the nucleus; _a_, attraction-sphere or
+archoplasm containing minute bodies called centrosomes; _cl_, membrane
+enclosing the cell externally, _nl_, membrane surrounding the nucleus;
+_c_, centrosomes.]
+
+Under favoring conditions, protoplasm has a power of performing
+chemical changes, which result in producing heat far more gently and
+continuously than it is produced by the combustion of inorganic
+bodies. Thus it is that the heat is produced which makes its presence
+evident to us in what we call "warm-blooded animals," the most
+warm-blooded of all being birds.
+
+Protoplasm has also the wonderful power of transforming certain
+adjacent substances into material like itself--into its own
+substance--and so, in a sense, creating a new material. Thus it is
+that organisms have the power to nourish themselves and grow. An
+animal would vainly swallow the most nourishing food if the ultimate,
+protoplasmic particles of its body had not this power of
+"transforming" suitable substances brought near them in ways to be
+hereinafter noticed.
+
+Without that, no organism could ever "grow." The growth of organisms
+is utterly different from the increase in size of inorganic bodies.
+Crystals, as we have seen, grow merely by external increment; but
+organisms grow by an increment which takes place in the very innermost
+substance of the tissues which compose their bodies, and the innermost
+substance of the cells which compose such tissues; this peculiar form
+of growth is termed _intussusception_.
+
+Protoplasm, after thus augmenting its mass, has a further power of
+spontaneous division, whereby the mass of the entire organism whereof
+such protoplasm forms a part, is augmented and so growth is brought
+about.
+
+The small particles of protoplasm which constitute "cells" are far
+indeed from being structureless. Besides the nucleus already mentioned
+there is a delicate network of threads of a substance called
+_chromatin_ within it, and another network permeating the fluid of the
+cell substance, which invest the nucleus often with further
+complications. These networks generally perform (or undergo) a most
+complex series of changes every time a cell spontaneously divides. In
+certain cases, however, it appears that the nucleus divides into two
+in a more simple fashion, the rest of the cell contents subsequently
+dividing--each half enclosing one part of the previously divided
+nucleus. It is by a continued process of cell division that the
+complex structures of the most complex organisms is brought about.
+
+The division of a cell, or particle of protoplasm, is indeed a
+necessary consequence of its complete nutrition.
+
+For new material can only be absorbed by its surface. But as the cell
+grows, the proportion borne by its surface to its mass, continually
+decreases; therefore this surface must soon be too small to take in
+nourishment enough, and the particle, or cell, must therefore either
+die or divide. By dividing, its parts can continue the nutritive
+process till their surface, in turn, becomes insufficient, when they
+must divide again, and so on. Thus the term "feeding" has two senses.
+"To feed a horse," ordinarily means to give it a certain quantity of
+hay, oats or what not; and such indeed is one kind of feeding. But
+obviously, if the nourishment so taken could not get from the stomach
+and intestines into the ultimate particles and cells of the horse's
+body, the horse could not be nourished, and still less could it grow.
+It is this latter process, called assimilation, which is the real and
+essential process of feeding, to which the process ordinarily so
+called is but introductory.
+
+Protoplasm has also the power of forming and ejecting from its own
+substance, other substances which it has made, but which are of a
+different nature to its own. This function, as before said, is termed
+secretion; and we know the liver secretes bile, and that the cow's
+udder secretes milk.
+
+Here again we have an external and an internal process. The milk is
+drawn forth from a receptacle, the udder, into which it finds its way,
+and so, in a superficial sense, it may be called an organ of
+secretion. Nevertheless the true internal secretion takes place in
+the innermost substance of the cells or particles of protoplasm, of
+the milk-land, which particles really form that liquid.
+
+But every living creature consists at first entirely of a particle of
+protoplasm. Therefore every other kind of substance which may be found
+in every kind of plant or animal, must have been formed through it,
+and be, in fact, a secretion from protoplasm. Such is the rosy cheek
+of an apple, or of a maiden, the luscious juice of the peach, the
+produce of the castor-oil plant, the baleen that lines the whale's
+enormous jaws, as well as that softest product, the fur of the
+chinchilla. Indeed, every particle of protoplasm requires, in order
+that it may live, a continuous process of exchange. It needs to be
+continuously first built up by food, and then broken down by
+discharging what is no longer needful for its healthy existence. Thus
+the life of every organism is a life of almost incessant change, not
+only in its being as a whole, but in that of all its protoplasmic
+particles also.
+
+[Illustration: FIG. 4. AMOEBA SHOWN IN TWO OF THE MANY IRREGULAR
+SHAPES IT ASSUMES. _(After Howes_.)
+
+The clear space within it is a contractile vesicle. The dark body is
+the nucleus. In the right-hand figure there is shown a particle of
+food, passing through the external surface.]
+
+
+Prominent among such processes is that of an interchange of gases
+between the living being and its environment. This process consists in
+an absorption of oxygen and a giving-out of carbonic acid, which
+exchange is termed respiration.
+
+Lastly, protoplasm has a power of motion when appropriately acted on.
+It will then contract or expand its shape by alternate protrusions and
+retractions of parts of its substance. These movements are termed
+amoebiform, because they quite resemble the movements of a small
+animalcule which is named amoeba. (See Fig. 4.)
+
+Such is the ultimate structure, and such are the fundamental
+activities or functions of living organisms, as far as they can here
+be described, from the lowest animalcule and unicellular plant, up to
+the most complex organisms and the body of man himself.
+
+[Illustration]
+
+
+
+
+INHABITANTS OF MY POOL
+
+(FROM MAGIC GLASSES.)
+
+BY ARABELLA B. BUCKLEY.
+
+
+The pool lies in a deep hollow among a group of rocks and boulders,
+close to the entrance of the cove, which can only be entered at low
+water; it does not measure more than two feet across, so that you can
+step over it, if you take care not to slip on the masses of green and
+brown seaweed growing over the rocks on its sides, as I have done many
+a time when collecting specimens for our salt-water aquarium. I find
+now the only way is to lie flat down on the rock, so that my hands and
+eyes are free to observe and handle, and then, bringing my eye down to
+the edge of the pool, to lift the seaweeds and let the sunlight enter
+into the chinks and crannies. In this way I can catch sight of many a
+small being either on the seaweed or the rocky ledges, and even
+creatures transparent as glass become visible by the thin outline
+gleaming in the sunlight. Then I pluck a piece of seaweed, or chip off
+a fragment of rock with a sharp-edged collecting knife, bringing away
+the specimen uninjured upon it, and place it carefully in its own
+separate bottle to be carried home alive and well.
+
+Now though this little pool and I are old friends, I find new
+treasures in it almost every time I go, for it is almost as full of
+living things as the heavens are of stars, and the tide as it comes
+and goes brings many a mother there to find a safe home for her little
+ones, and many a waif and stray to seek shelter from the troublous
+life of the open ocean.
+
+You will perhaps find it difficult to believe that in this rock-bound
+basin there can be millions of living creatures hidden away among the
+fine feathery weeds; yet so it is. Not that they are always the same.
+At one time it may be the home of myriads of infant crabs, not an
+eighth of an inch long, another of baby sea-urchins only visible to
+the naked eye as minute spots in the water, at another of young
+jelly-fish growing on their tiny stalks, and splitting off one by one
+as transparent bells to float away with the rising tide. Or it may be
+that the whelk has chosen this quiet nook to deposit her leathery
+eggs; or young barnacles, periwinkles, and limpets are growing up
+among the green and brown tangles, while the far-sailing velella and
+the stay-at-home sea-squirts, together with a variety of other
+sea-animals, find a nursery and shelter in their youth in this quiet
+harbor of rest.
+
+And besides these casual visitors there are numberless creatures which
+have lived and multiplied there, ever since I first visited the pool.
+Tender red, olive-colored, and green seaweeds, stony corallines, and
+acorn-barnacles lining the floor, sea-anemones clinging to the sides,
+sponges tiny and many-colored hiding under the ledges, and limpets and
+mussels wedged in the cracks. These can be easily seen with the naked
+eye, but they are not the most numerous inhabitants; for these we
+must search with a magnifying glass, which will reveal to us wonderful
+fairy-forms, delicate crystal vases with tiny creatures in them whose
+transparent lashes make whirlpools in the water, living crystal bells
+so tiny that whole branches of them look only like a fringe of hair,
+jelly globes rising and falling in the water, patches of living jelly
+clinging to the rocky sides of the pool, and a hundred other forms,
+some so minute that you must examine the fine sand in which they lie
+under a powerful microscope before you can even guess that they are
+there.
+
+[Illustration: FIG. 1. GROUP OF SEAWEEDS.
+
+(Natural size.)
+
+1, _Ulva Linza._ 2, _Sphacelaria filicina._ 3, _Polysiphonia
+urceolata._ 4, _Corallina officinalis._]
+
+So it has proved a rich hunting-ground, where summer and winter,
+spring and autumn, I find some form to put under my magic glass. There
+I can watch it for weeks growing and multiplying under my care; moved
+only from the aquarium, where I keep it supplied with healthy
+sea-water, to the tiny transparent trough in which I place it for a
+few hours to see the changes it has undergone. I could tell you
+endless tales of transformations in these tiny lives, but I want
+to-day to show you a few of my friends, most of which I brought
+yesterday fresh from the pool, and have prepared for you to examine.
+
+[Illustration: FIG. 2. _Ulva lactuca_, A GREEN-SEAWEED, GREATLY
+MAGNIFIED TO SHOW STRUCTURE. (_After Orested)._
+
+s, Spores in the cells, _ss_, Spores swimming out. _h_, Holes through
+which spores have escaped.]
+
+Let us begin with seaweeds. I have said that there are three leading
+colors in my pool--green, olive, and red--and these tints mark roughly
+three kinds of weed, though they occur in an endless variety of
+shapes. Here is a piece of the beautiful pale green seaweed, called
+the Laver or Sea-Lettuce, _Ulva Linza_ (1, Fig. 1),[1] which grows in
+long ribbons in a sunny nook in the water. I have placed under the
+first microscope a piece of this weed which is just sending out young
+seaweeds in the shape of tiny cells, with lashes very like those we
+saw coming from the moss-flower, and I have pressed them in the
+position in which they would naturally leave the plant. You will also
+see on this side several cells in which these tiny spores are forming,
+ready to burst out and swim; for this green weed is merely a
+collection of cells, like the single-celled plants on land. Each cell
+can work as a separate plant; it feeds, grows, and can send out its
+own young spores.
+
+[Footnote 1: The slice given in Fig. 2 is from a broader-leaved form,
+_U. lactuca_, because this species, being composed of only one layer
+of cells, is better seen. _Ulva Linza_ is composed of two layers of
+cells.]
+
+This deep olive-green feathery weed (2, Fig. 1), of which a piece is
+magnified under the next microscope (2, Fig. 3), is very different. It
+is a higher plant, and works harder for its living, using the darker
+rays of sunlight which penetrate into shady parts of the pool. So it
+comes to pass that its cells divide the work. Those of the feathery
+threads make the food, while others, growing on short stalks on the
+shafts of the feather, make and send out the young spores.
+
+Lastly, the lovely red threadlike weeds, such as this _Polysiphonia
+urceolata_ (3, Fig. 1), carry actual urns on their stems like those of
+mosses. In fact, the history of these urns (see 3, Fig. 3), is much
+the same in the two classes of plants, only that instead of the urn
+being pushed up on a thin stalk as in the moss, it remains on the
+seaweed close down to the stem, when it grows out of the plant-egg,
+and the tiny plant is shut in till the spores are ready to swim out.
+
+[Illustration: FIG. 3. THREE SEAWEEDS OF FIG. 1 MUCH MAGNIFIED TO SHOW
+FRUITS. (_Harvey._)
+
+2, _Sphacelaria filicina._ 3, _Polysiphonia urceolata._ 4, _Corallina
+officinalis._]
+
+The stony corallines (4, Figs. 1 and 3), which build so much carbonate
+of lime into their stems, are near relations of the red seaweeds.
+There are plenty of them in my pool. Some of them, of a deep purple
+color, grow upright in stiff groups about three or four inches high;
+and others, which form crusts over the stones and weeds, are a pale
+rose color; but both kinds, when the plant dies, leaving the stony
+skeleton (1, Fig. 4), are a pure white, and used to be mistaken for
+corals. They belong to the same order of plants as the red weeds,
+which all live in shady nooks in the pools, and are the highest of
+their race.
+
+[Illustration: FIG. 4. CORALLINE AND SERTULARIA, TO SHOW LIKENESS
+BETWEEN THE ANIMAL SERTULARIA AND THE PLANT CORALLINE.
+
+1, _Corallina officinalis._ 2, _Sertularia filicula._]
+
+My pool is full of different forms of these four weeds. The green
+ribbons float on the surface rooted to the sides of the pool, and, as
+the sun shines upon it, the glittering bubbles rising from them show
+that they are working up food out of the air in the water, and giving
+off oxygen. The brown weeds lie chiefly under the shelves of rocks,
+for they can manage with less sunlight, and use the darker rays which
+pass by the green weeds; and last of all, the red weeds and
+corallines, small and delicate in form, line the bottom of the pool in
+its darkest nooks.
+
+And now if I hand round two specimens,--one a coralline, and the other
+something you do not yet know,--I am sure you will say at first sight
+that they belong to the same family, and, in fact, if you buy at the
+seaside a group of seaweeds gummed on paper, you will most likely get
+both these among them. Yet the truth is; that while the coralline (1,
+Fig. 4) is a plant, the other specimen (2), which is called
+_Sertularia filicula_, is an animal.
+
+This special sertularian grows up right in my pool on stones or often
+on seaweeds, but I have here (Fig. 5) another and much smaller one
+which lives literally in millions hanging its cups downwards. I find
+it not only under the narrow ledges of the pool sheltered by the
+seaweed, but forming a fringe along all the rocks on each side of the
+cove near to low-water mark, and for a long time I passed it by
+thinking it was of no interest. But I have long since given up
+thinking this of anything, especially in my pool, for my magic glass
+has taught me that there is not even a living speck which does not
+open out into something marvellous and beautiful. So I chipped off a
+small piece of rock and brought the fringe home, and found, when I
+hung it up in clear sea-water as I have done over this glass trough
+(Fig. 5) and looked at it through the lens, that each thread of the
+dense fringe, in itself not a quarter of an inch deep, turns out to be
+a tiny sertularian with at least twenty mouths. You can see this with
+your pocket lens even as it hangs here, and when you have examined it
+you can by and by take off one thread and put it carefully in the
+trough. I promise you a sight of the most beautiful little beings
+which exist in nature.
+
+[Illustration: FIG. 5. _Sertularia tenella_, HANGING FROM A SPLINT OF
+ROCK OVER A WATER TROUGH. ALSO PIECE ENLARGED TO SHOW THE ANIMAL
+PROTRUDING.]
+
+Come and look at it. It is a horny-branched stem with a double row of
+tiny cups all along each side. Out of these cups there appear a row of
+tiny cups all along each side (see Fig. 5), Out of these cups there
+appear from time to time sixteen minute transparent tentacles as fine
+as spun glass, which wave about in the water. If you shake the glass a
+little, in an instant each crystal star vanishes into its cup, to come
+out again a few minutes later; so that now here, now there, the
+delicate animal-flowers spread out on each side of the stem, and the
+tree is covered with moving beings. These tentacles are feelers, which
+lash food into a mouth and stomach in each cup, where it is digested
+and passed, through a hole in the bottom, along a jelly thread which
+runs down the stem and joins all the mouths together. In this way the
+food is distributed all over the tree, which is, in fact, one animal
+with many feeding-cups. Some day I will show you one of these cups
+with the tentacles stretched out and mounted on a slide, so that you
+can examine a tentacle with a very strong magnifying power. You will
+then see that it is dotted over with cells, in which are coiled fine
+threads. The animal uses these threads to paralyze the creatures on
+which it feeds, for at the base of each thread there is a poison
+gland.
+
+In the larger Sertularia the whole branched tree is connected by jelly
+threads, running through the stem, and all the thousands of mouths are
+spread out in the water. One large form called _Sertularia cupressina_
+grows sometimes three feet high and bears as many as a hundred
+thousand cups, with living mouths, on its branches.
+
+The next of my minute friends I can only show to the class in a
+diagram, but you will see it under the fourth microscope by and by. I
+had great trouble in finding it yesterday, though I know its haunts
+upon the green weed, for it is so minute and transparent that even
+when the weed is in a trough a magnifying-glass will scarcely detect
+it. And I must warn you that if you want to know any of the minute
+creatures we are studying, you must visit one place constantly. You
+may in a casual way find many of them on seaweed, or in the damp ooze
+and mud, but it will be by chance only; to look for them with any
+certainty you must take trouble in making their acquaintance.
+
+[Illustration: FIG. 6. _Thuricolla folliculata_ and _Chilomonas
+amygdalum_. (_Saville Kent_.)
+
+1, _Thuricolla_ erect. 2, Retracted. 3, Dividing. 4, _Chilomonas
+amygdalum. hc,_ Horny carapace, _cv_, Contractile vesicle. _v_ Closing
+valves.]
+
+Turning then to the diagram (Fig. 6) I will describe it as I hope you
+will see it under the microscope--a curious, tiny, perfectly
+transparent open-mouthed vase standing upright on the weed, and having
+an equally transparent being rising up in it and waving its tiny
+lashes in the water. This is really all one animal, the vase _hc_
+being the horny covering or carapace of the body, which last stands up
+like a tube in the centre. If you watch carefully, you may even see
+the minute atoms of food twisting round inside the tube until they are
+digested, after they have been swept in at the wide open mouth by the
+whirling lashes. You will see this more clearly if you put a little
+rice-flour, very minutely powdered and colored by carmine, into the
+water; for you can trace these red atoms into some round spaces called
+_vacuoles_ which are dotted over the body of the animal, and are
+really globules of watery fluid in which the food is probably partly
+digested.
+
+You will notice, however, one round clear space _(cv)_ into which they
+do not go, and after a time you will be able to observe that this
+round spot closes up or contracts very quickly, and then expands again
+very slowly. As it expands it fills with a clear fluid, and
+naturalists have not yet decided exactly what work it does. It may
+serve the animal either for breathing, or as a very simple heart,
+making the fluids circulate in the tube. The next interesting point
+about this little being is the way it retreats into its sheltering
+vase. Even while you are watching, it is quite likely it may all at
+once draw itself down to the bottom as in No. 2, and folding down the
+valves _w_ of horny teeth which grow on each side, shut itself in from
+some fancied danger. Another very curious point is that, besides
+sending forth young ones, these creatures multiply by dividing in two
+(see No. 3, Fig. 6), each one closing its own part of the vase into a
+new home.
+
+There are hundreds of these Infusoria, as they are called, in my pond,
+some with vases, some without, some fixed to weeds and stones, others
+swimming about freely. Even in the water-trough in which this
+Thuricolla stands, I saw several smaller forms, and the next
+microscope has a trough filled with the minutest form of all, called a
+Monad. These are so small that two thousand of them could lie side by
+side in an inch; that is, if you could make them lie at all, for they
+are the most restless little beings, darting hither and thither,
+scarcely even halting except to turn back. And yet though there are so
+many of them, and as far as we know they have no organs of sight, they
+never run up against each other, but glide past more cleverly than any
+clear-sighted fish. These creatures are mostly to be found among
+decaying seaweed, and though they are so tiny, you can still see
+distinctly the clear space contracting and expanding within them.
+
+[Illustration: FIG. 7. LIVING DIATOMS.
+
+_a, Cocconema lanceolatum. b, Bacillaria paradoxa. c, Gomphonema
+marinum. d, Diatoma hyalina_.]
+
+But if there are so many thousands of mouths to feed, on the tree-like
+Sertulariæ as well as in all these Infusoria, where does the food come
+from? Partly from the numerous atoms of decaying life all around, and
+the minute eggs of animals and spores of plants; but besides these,
+the pool is full of minute living plants--small jelly masses with
+solid coats of flint which are moulded into most lovely shapes. Plants
+formed of jelly and flint! You will think I am joking, but I am not.
+These plants, called Diatoms, which live both in salt and fresh water,
+are single cells feeding and growing just like those we took from the
+water-butt, only that instead of a soft covering they build up a
+flinty skeleton. They are so small, that many of them must be
+magnified to fifty times their real size before you can even see them
+distinctly. Yet the skeletons of these almost invisible plants are
+carved and chiselled in the most delicate patterns. I showed you a
+group of these in our lecture on magic glasses, and now I have brought
+a few living ones that we may learn to know them. The diagram (Fig. 7)
+shows the chief forms you will see on the different slides.
+
+The first one, _Sacillaria paradoxa_ (_b_, Fig. 7), looks like a
+number of rods clinging one to another in a string, but each one of
+these is a single-celled plant with a jelly cell surrounding the
+flinty skeleton. You will see that they move to and fro over each
+other in the water.
+
+The next two forms, _a_ and _c_, look much more like plants, for the
+cells arrange themselves on a jelly stem, which by and by disappears,
+leaving only the separate flint skeletons. The last form, _d_, is
+something midway between the other forms, the separate cells hang on
+to each other and also on to a straight jelly stem.
+
+[Illustration: FIG. 8. A DIATOM (_Diatoma vulgare_) GROWING.
+
+_a, b,_ Flint skeleton inside the jelly-cell. _a, c_ and _d, b_, Two
+flint skeletons formed by new valves, _c_ and _d_, forming within the
+first skeleton.]
+
+Another species of Diatoma (Fig. 8) called _Diatoma vulgare_, is a
+very simple and common form, and will help to explain how these plants
+grow. The two flinty valves _a, b_ inside the cell are not quite the
+same size; the older one _a_ is larger than the younger one _b_ and
+fits over it like the cover of a pill-box. As the plant grows, the
+cell enlarges and forms two more valves, one _c_ fitting into the
+cover _a_, so as to make a complete box _ac_, and a second, _d_, back
+to back with _c_, fitting into the valve _b_, and making another
+complete _bd_. This goes on very rapidly, and in this plant each new
+cell separates as it is formed, and the free diatoms move about quite
+actively in the water.
+
+If you consider for a moment, you will see that, as the new valves
+always fit into the old ones, each must be smaller than the last, and
+so there comes a time when the valves have become too small to go on
+increasing. Then the plant must begin afresh. So the two halves of the
+last cell open, and throwing out their flinty skeletons, cover
+themselves with a thin jelly layer, and form a new cell which grows
+larger than any of the old ones. These, which are spore-cells, then
+form flinty valves inside, and the whole thing begins again.
+
+Now, though the plants themselves die, or become the food of minute
+animals, the flinty skeletons are not destroyed, but go on
+accumulating in the waters of the ponds, lakes, rivers, and seas, all
+over the world. Untold millions have no doubt crumbled to dust and
+gone back into the waters, but untold millions also have survived. The
+towns of Berlin in Europe and of Richmond in the United States are
+actually built upon ground called "infusorial earth," composed almost
+entirely of valves of these minute diatoms which have accumulated to a
+thickness of more than eighty feet! Those under Berlin are fresh-water
+forms, and must have lived in a lake, while those of Richmond belong
+to salt-water forms. Every inch of the ground under those cities
+represents thousands and thousands of living plants which flourished
+in ages long gone by, and were no larger than those you will see
+presently under the microscope.
+
+These are a very few of the microscopic inhabitants of my pond, but,
+as you will confuse them if I show you too many, we will conclude with
+two rather larger specimens, and examine them carefully. The first,
+called the Cydippe, is a lovely, transparent living ball, which I want
+to explain to you because it is so wondrously beautiful. The second,
+the Sea-mat or Flustra, looks like a crumpled drab-colored seaweed,
+but is really composed of many thousands of grottos, the homes of tiny
+sea-animals.
+
+[Illustration: FIG. 9. _Cydippe Pileus_.
+
+1, Animal with tentacles _t_, bearing small tendrils _t'_. 2, Body of
+animal enlarged. _m_, Mouth. _c_, Digestive cavity. _s_, Sac into
+which the tentacles are withdrawn. _p_, Bands with comb-like plates.
+3, Portion of a band enlarged to show the moving plates _p_.]
+
+Let us take the Cydippe first (1, Fig. 9). I have six here, each in a
+separate tumbler, and could have brought many more, for when I dipped
+my net in the pool yesterday such numbers were caught in it that I
+believe the retreating tide must just have left a shoal behind. Put a
+tumbler on the desk in front of you, and if the light falls well upon
+it you will see a transparent ball about the size of a large pea
+marked with eight bright bands, which begin at the lower end of the
+ball and reach nearly to the top, dividing the outside into sections
+like the ribs of a melon. The creature is so perfectly transparent
+that you can count all the eight bands.
+
+At the top of the ball is a slight bulge which is the mouth (_m_ 2,
+Fig. 9), and from it, inside the ball hangs a long bag or stomach,
+which opens below into a cavity, from which two canals branch out, one
+on each side, and these divide again into four canals which go one
+into each of the tubes running down the bands. From this cavity the
+food, which is digested in the stomach, is carried by the canals all
+over the body. The smaller tubes which branch out of these canals
+cannot be seen clearly without a very strong lens, and the only other
+parts you can discern in this transparent ball are two long sacs on
+each side of the lower end. These are the tentacle sacs, in which are
+coiled up the tentacles, which we shall describe presently. Lastly you
+can notice that the bands outside the globe are broader in the middle
+than at the ends, and are striped across by a number of ridges.
+
+In moving the tumblers the water has naturally been shaken, and the
+creature being alarmed will probably at first remain motionless. But
+very soon it will begin to play in the water, rising and falling, and
+swimming gracefully from side to side. Now you will notice a curious
+effect, for the bands will glitter and become tinged with prismatic
+colors, till, as it moves more and more rapidly these colors,
+reflected in the jelly, seem to tinge the whole ball with colors like
+those on a soap-bubble, while from the two sacs below come forth two
+long transparent threads like spun glass. At first these appear to be
+simple threads, but as they gradually open out to about four or five
+inches, smaller threads uncoil on each side of the line till there are
+about fifty on each line. These short tendrils are never still for
+long; as the main threads wave to and fro, some of the shorter ones
+coil up and hang like tiny beads, then these uncoil and others roll
+up, so that these graceful floating lines are never two seconds alike.
+
+We do not really know their use. Sometimes the creature anchors itself
+by them, rising and falling as they stretch out or coil up; but more
+often they float idly behind it in the water. At first you would
+perhaps think that they served to drive the ball through the water,
+but this is done by a special apparatus. The cross ridges which we
+noticed on the bands are really flat comb-like plates (_p_, Fig. 9),
+of which there are about twenty or thirty on each band; and these
+vibrate very rapidly, so that two hundred or more paddles drive the
+tiny ball through the water. This is the cause of the prismatic
+colors; for iridescent tints are produced by the play of light upon
+the glittering plates, as they incessantly change their angle.
+Sometimes they move all at once, sometimes only a few at a time, and
+it is evident the creature controls them at will.
+
+This lovely fairy-like globe, with its long floating tentacles and
+rainbow tints, was for a long time classed with the jelly-fish; but it
+really is most nearly related to the sea-anemones, as it has a true
+central cavity which acts as a stomach, and many other points in
+common with the _Actinozoa_. We cannot help wondering, as the little
+being glides hither and thither, whether it can see where it is going.
+It has nerves of a low kind which start from a little dark spot (_ng_)
+exactly at the south pole of the ball, and at that point a sense-organ
+of some kind exists, but what impression the creature gains from it of
+the world outside we cannot tell.
+
+I am afraid you may think it dull to turn from such a beautiful being
+as this, to the gray leaf which looks only like a dead dry seaweed;
+yet you will be wrong, for a more wonderful history attaches to this
+crumpled dead-looking leaf than to the lovely jelly-globe.
+
+[Illustration: FIG. 10. THE SEA-MAT OR FLUSTRA (_Flustra foliacea_).
+
+1, Natural size. 2, Much magnified, _s_, Slit caused by drawing in of
+the animal _a_.]
+
+First of all I will pass round pieces of the dry leaf (1, Fig. 10),
+and while you are getting them I will tell you where I found the
+living ones. Great masses of the Flustra, as it is called, line the
+bottom and sides of my pool. They grow in tufts, standing upright on
+the rock, and looking exactly like hard gray seaweeds, while there is
+nothing to lead you to suspect that they are anything else. Yesterday
+I chipped off very carefully a piece of rock with a tuft upon it, and
+have kept it since in a glass globe by itself with sea-water, for the
+little creatures living in this marine city require a very good supply
+of healthy water and air. I have called it a "marine city," and now I
+will tell you why. Take the piece in your hand and run your finger
+gently up and down it; you will glide quite comfortably from the lower
+to the higher part of the leaf, but when you come back you will feel
+your finger catch slightly on a rough surface. Your pocket lens will
+show you why this is, for if you look through it at the surface of the
+leaf you will see it is not smooth, but composed of hundreds of tiny
+alcoves with arched tops; and on each side of these tops stand two
+short blunt spines, making four in all, pointing upwards, so as partly
+to cover the alcove above. As your finger went up it glided over the
+spines, but on coming back it met their points. This is all you can
+see in the dead specimen; I must show you the rest by diagrams, and by
+and by under the microscope.
+
+First, then, in the living specimen which I have here, those alcoves
+are not open as in the dead piece, but covered over with a transparent
+skin, in which, near the top of the alcove just where the curve
+begins, is a slit (_s_ 2, Fig. 10) Unfortunately, the membrane
+covering this alcove is too dense for you to distinguish the parts
+within. Presently, however, if you are watching a piece of this living
+leaf in a flat water-cell under the microscope, you will see the slit
+slowly open, and begin to turn as it were inside out, exactly like the
+finger of a glove, which has been pushed in at the tip, gradually
+rises up when you put your finger inside it. As this goes on, a bundle
+of threads appears, at first closed like a bud, but gradually opening
+out into a crown of tentacles, each one clothed with hairs. Then you
+will see that the slit was not exactly a slit after all, but the round
+edge where the sac was pushed in. Ah! you will say, you are now
+showing me a polyp like those on the sertularian tree. Not so fast, my
+friend; you have not studied what is still under the covering skin and
+hidden in the living animal. I have, however, prepared a slide with
+this membrane removed and there you can observe the different parts,
+and learn that each one of these alcoves contains a complete animal,
+and not merely one among many mouths, like the polyp on Sertularia.
+
+[Illustration: FIG. 11. DIAGRAM OF THE ANIMAL IN THE FLUSTRA OR
+SEA-MAT.
+
+1, Animal protruding. 2, Animal retracted in the sheath, _sh_,
+Covering sheath, _s_, Slit. _t_, Tentacles. _m_, Mouth. _th_, Throat,
+_st_, Stomach. _i_, Intestine, _r_, Retractor muscle, _e_, Egg-forming
+parts. _g_, Nerve-ganglion.]
+
+Each of these little beings (_a_, Fig. 10) living in its alcove has a
+mouth, throat, stomach, intestine, muscles, and nerves starting from
+the ganglion of nervous matter, besides all that is necessary for
+producing eggs and sending forth young ones. You can trace all these
+under the microscope (see 2, Fig. 11) as the creature lies curiously
+doubled up in its bed, with its body bent in a loop; the intestine
+_i_, out of which the refuse food passes, coming back close up to the
+slit. When it is at rest, the top of the sac in which it lies is
+pulled in by the retractor muscle _r_, and looks, as I have said, like
+the finger of a glove with the top pushed in. When it wishes to feed
+this top is drawn out by muscles running round the sac, and the
+tentacles open and wave in the water (1, Fig. 11).
+
+Look now at the alcoves, the homes of these animals; see how tiny they
+are and how closely they fit together. Mr. Gosse, the naturalist, has
+reckoned that there are six thousand, seven hundred and twenty alcoves
+in a square inch; then if you turn the leaf over you will see that
+there is another set, fixed back to back with these, on the other
+side, making in all, thirteen thousand, four hundred and forty
+alcoves. Now a moderate-sized leaf of flustra measures about three
+square inches, taking all the rounded lobes into account, so you will
+see we get forty thousand, three hundred and twenty as a rough
+estimate of the number of beings on this one leaf. But if you look at
+this tuft I have brought, you will find it is composed of twelve such
+leaves, and this after all is a very small part of the mass growing
+round my pool. Was I wrong, then, when I said my miniature ocean
+contains as many millions of beings as there are stars in the heavens?
+
+You will want to know how these leaves grew, and it is in this way.
+First a little free swimming animal, a mere living sac provided with
+lashes, settles down and grows into one little horny alcove, with its
+live creature inside, which in time sends off from it three to five
+buds, forming alcoves all round the top and sides of the first one,
+growing on to it. These again bud out, and you can thus easily
+understand that, in this way, in time a good-sized leaf is formed.
+Meanwhile the creatures also send forth new swimming cells, which
+settle down near to begin new leaves, and thus a tuft is formed; and
+long after the beings in earlier parts of the leaf have died and left
+their alcoves empty, those round the margin are still alive and
+spreading....
+
+If you can trace the spore-cells and urns in the seaweeds, observe the
+polyps in the Sertularia, and count the number of mouths on a branch
+of my animal fringe (Sertularia tenella); if you make acquaintance
+with the Thuricolla in its vase, and are fortunate enough to see one
+divide in two; if you learn to know some of the beautiful forms of
+diatoms, and can picture to yourself the life of the tiny inhabitants
+of the Flustra; then you will have used your microscope with some
+effect, and be prepared for an expedition to my pool, where we will go
+together some day to seek new treasures.
+
+[Illustration]
+
+
+
+
+NOTES
+
+
+AGASSIZ, J.L.R., naturalist, born in Switzerland, 1807; died,
+Cambridge, Mass., 1873. In 1846 he came to America, after having
+gained a high reputation in Europe, to deliver a course of lectures in
+Boston "On the Plan of the Creation," and met with such success that
+he spent the rest of his days there, declining an invitation to return
+to his native country and to Paris. In 1848 he was elected to the
+chair of Natural History at Harvard. In 1850-51 he went on an
+expedition to the Florida Reefs. In 1858 he founded and organized the
+Museum of Comparative Zoölogy at Cambridge--and, later on, went on his
+important voyage to Brazil. In 1872 he founded and organized the
+summer school of Natural History at Buzzard's Bay. He wrote "The
+Fishes of Brazil," "A Study of Glaciers," "Natural History of the
+Fresh Water Fishes of Central Europe," "Contributions to the Natural
+History of the United States" (unfinished), and with his wife, "A
+Journey in Brazil."
+
+BALL, PROF. SIR R.S., English astronomer, born in Dublin, 1840. Was
+appointed Lord Ross's astronomer in 1865. Professor of mathematics and
+mechanics at the Royal Irish College of Science in 1873, and is now
+astronomer royal for Ireland. He is the author of "The Story of the
+Heavens," "Starland," etc., and is well known as a successful lecturer
+on astronomical subjects in this country.
+
+DARWIN, CHARLES R., English naturalist, born, 1809; died, 1882. He
+first formulated what is known as the principle of Natural Selection.
+In 1831 he went in the famous scientific voyage of the _Beagle_ as
+naturalist, and afterwards published an account of it. He was one of
+the most thorough, careful, and painstaking scientific men of this or
+any age. He is the author of many famous books. "The Origin of
+Species," "The Descent of Man," "Insectivorous Plants," "The Power of
+Movement in Plants," "The Structure and Distribution of Coral Reefs,"
+"Geological Observations on Volcanic Islands." "The Formation of
+Vegetable Mould" was his last published work.
+
+FLAMMARION, C., famous French astronomer, born, 1842. He has written
+many popular works on astronomy, most of which have been translated
+into English. "The Stars," "The World Before the Creation," "Uranus,"
+"Comets," "Popular Astronomy," are among his best known.
+
+HOLDEN, PROF. E.S., American astronomer, born at St. Louis, 1846.
+Lieutenant engineers, U.S.A., 1870-73; professor mathematics, U.S.N.,
+1873-81; director Washburn Observatory, 1881-85; president University
+of California, 1883-88; director Lick Observatory, 1888-98. Is a
+member of several learned societies of Europe. Is the author of a
+"Life of William Herschel," "A Hand-book of the Lick Observatory,"
+"Earth and Sky," "Primer of Heraldry," "Elementary Astronomy," "Family
+of the Sun," "Essays in Astronomy," "Stories of the Great
+Astronomers," etc.
+
+HUXLEY, T.H., English biologist, born, 1825; died, 1895. Went on an
+exploring expedition on the _Rattlesnake_, and devoted himself to the
+study of marine life. For his scientific researches he received many
+honors. His lectures were models of clearness, and he could simplify
+the most difficult subjects. He strongly advocated Darwin's views and
+evolutionist doctrines. His writings are numerous and many of them
+technical. Among some of the most popular are "Man's Place in Nature,"
+his "Lay Sermons," "Critiques and Addresses," "American Addresses,"
+"Physiography," "Science and Culture," "Lessons in Elementary
+Physiology," etc.
+
+KINGSLEY, C., English clergyman and author, born, 1819; died, 1875.
+Wrote "Westward, Ho!" which every boy should read, "Hypatia," "Alton
+Locke," "Hereward the Wake," etc., and a charming book of travel,
+entitled, "At Last." His "Water Babies" is exceedingly popular, and
+his "Heroes" is a book much appreciated by the boys and girls alike.
+
+PROCTOR, R.A., English astronomer, born, 1834; died, 1888. He was a
+very popular writer, and lectured on astronomical subjects in this
+country, and in England and her colonies. A memorial teaching
+observatory is erected in his honor near San Diego, Cal. He was a man
+of untiring industry, an athlete, a musician, and a chess-player. His
+books are numerous. Among them are "Half Hours with the Telescope,"
+"Other Worlds than Ours," "Light Science for Leisure Hours," "The
+Expanse of Heaven," "The Moon," "The Borderland of Science," "Our
+Place Among Infinites," "Myths and Marvels of Astronomy," "The
+Universe of Suns," "Other Suns than Ours," etc.
+
+SHALER, N.S., professor of geology at Harvard. Born Newport, Ky.,
+1841. Served in the Union Army during the Civil War. Instructor
+zoölogy, geology, and paleontology, Lawrence Scientific School, till
+1887. Since then at Harvard. Is the author of "Kentucky a Pioneer
+Commonwealth," "The Story of Our Continent," "The Interpretation of
+Nature," "Feature of Coasts and Oceans," "Domesticated Animals," "The
+Individual," "Study of Life and Death," etc.
+
+THOMPSON, SIR C. WYVILLE, English zoölogist, born, 1830; died, 1882.
+He conducted scientific dredging expeditions in the _Lightning_ and
+_Porcupine_, 1868-69, and was the scientific head of the famous voyage
+of 68,900 miles in the _Challenger_ for deep-sea explorations
+(1872-76). His books are "The Depths of the Sea," and "The Voyage of
+the Challenger."
+
+TYNDALL, JOHN, English physicist, born, 1820. Began his original
+researches in 1847, when teacher of physics in Queenwood College. He
+and Professor Huxley visited the Alps together, and they wrote a work
+on the structure and nature of glaciers. It is impossible to detail
+the work he has done; but his inquiries and experiments in connection
+with light, heat, sound, and electricity have all had practical
+results. He is a popular lecturer, and devoted the proceeds of a
+lecturing tour in this country to founding scholarships at Harvard and
+Columbia Colleges, for students devoting themselves to original
+research. Among his books are "Glaciers of the Alps," "Mountaineering,"
+"Heat as a Mode of Motion," "On Radiation," "Hours of Exercise in the
+Alps," "Fragments of Science," "The Floating Matter of the Air," and
+volumes on Light, Sound, Electricity, and the forms of water.
+
+WALLACE, A.R., English naturalist and traveller, born 1822; was
+educated as land surveyor and architect, but afterwards devoted
+himself entirely to Natural History. He explored the Valley of the
+Amazon and Rio Negro, 1848-52, and travelled in the Malay Archipelago
+and Papua, 1854-62, publishing the results of his explorations later
+on. He also wrote "Contributions to the Theory of Natural Selection,"
+"Miracles and Modern Spiritualism," "Geographical Distribution of
+Animals," "Tropical Nature," "Island Life," etc.
+
+GIBERNE, AGNES, English author--living. Began to write at seven years
+old. Her first story for children was published when she was only
+seventeen. Her stories for children have not been so popular as her
+scientific writings, "Sun, Moon, and Stars," "The Starry Skies,"
+"Among the Stars," "The Ocean of Air," "The World's Foundations,"
+"Radiant Suns," etc.
+
+WILSON, ANDREW, English physiologist and lecturer, born, 1852. Is the
+author of "Studies on Life and Sense," "Leisure Time Studies,"
+"Science Stories," "Chapters on Evolution," "Wild Animals," "Brain and
+Nerve," etc., and is a constant contributor on scientific subjects to
+the magazines and newspapers, contributing weekly "Science Jottings"
+to the "Illustrated London News"
+
+
+
+
+WONDERS OF EARTH, SEA, AND SKY
+
+SUGGESTIONS FOR SUPPLEMENTARY READING
+
+
+  Wonder Stories of Science
+    D.N. BEACH
+
+  Wonders in Monsterland
+    EDWARD W.D. CUMING
+
+  Ocean Wonders
+    W.E. DAMON
+
+  Among the Stars
+    AGNES GIBERNE
+
+  The Scenery of the Heavens
+    JOHN ELLARD GORR
+
+  Coal and the Coal Miners
+    HOMER GREENE
+
+  Wonders of the Moon
+    A. GUILLEMIN
+
+  The Sea and Its Living Wonders.
+    G. HARTWIG
+
+  The Wonders of Plant Life Under the Microscope
+    SOPHIE B. HERRICK
+
+  Marvels of Animal Life
+    CHARLES F. HOLDER
+
+  Old Ocean
+    ERNEST INGERSOLL
+
+  Modern Seven Wonders of the World
+    C. KENT
+
+  Madam How and Lady Why
+    CHARLES KINGSLEY
+
+  Wonders of Optics
+    F. MARION
+
+  The Wonders of Science
+    HENRY MAYHEW
+
+  Wonders of Man and Nature
+    E. MENAULT
+
+  A Century of Electricity
+    T.C. MENDENHALL
+
+  The Orbs of Heaven
+    ORMSBY S. MITCHELL
+
+  Under Foot
+    LAURA D. NICHOLS
+
+  Myths and Marvels of Astronomy
+    R.A. PROCTOR
+
+  The Wonders of the World
+    CHARLES G. ROSENBERG
+
+  The Wonders of Nature
+    PROFESSOR RUDOLPH
+
+  Volcanoes of North America
+    ISRAEL COOK RUSSELL
+
+  Aspects of the Earth
+    N.S. SHALER
+
+  Wonders of the Bird World
+    R.B. SHARPE
+
+  The Wonders of Water
+    GASTON TISSANDIER
+
+  Total Eclipses of the Sun
+    MABEL L. TODD
+
+  Wonders of Insect Life
+    JOSEPH C. WILLET
+
+
+
+*** END OF THE PROJECT GUTENBERG EBOOK 15884 ***
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+<div>*** START OF THE PROJECT GUTENBERG EBOOK 15884 ***</div>
+
+<hr class="full">
+<p>&nbsp;</p>
+<p>&nbsp;</p>
+    <span class="pagenum"><a id="pagei"></a>[pg i]</span>
+
+    <h1>YOUNG FOLKS'<br>
+    LIBRARY</h1>
+
+    <h4>SELECTIONS FROM THE CHOICEST LITERATURE OF ALL<br>
+    LANDS; FOLK-LORE, FAIRY TALES, FABLES, LEGENDS,<br>
+    NATURAL HISTORY, WONDERS OF EARTH, SEA<br>
+    AND SKY, ANIMAL STORIES, SEA TALES,<br>
+    BRAVE DEEDS, EXPLORATIONS, STORIES<br>
+    OF SCHOOL AND COLLEGE LIFE,<br>
+    BIOGRAPHY, HISTORY, PATRIOTIC<br>
+    ELOQUENCE, POETRY</h4>
+
+    <p>&nbsp;</p>
+
+    <h3>THIRD EDITION</h3>
+
+    <h5>REVISED IN CONFERENCE BY</h5>
+
+    <h3>THOMAS BAILEY ALDRICH, EDITOR-IN-CHIEF,</h3>
+
+    <h4>PRESIDENT WILLIAM JEWETT TUCKER,<br>
+    HAMILTON WRIGHT MABIE, HENRY<br>
+    VAN DYKE, NATHAN HASKELL DOLE</h4>
+
+    <p>&nbsp;</p>
+
+    <p class="center"><i>TWENTY
+    VOLUMES&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;RICHLY
+    ILLUSTRATED</i></p>
+
+    <p>&nbsp;</p>
+
+    <h5>BOSTON<br>
+    HALL AND LOCKE COMPANY<br>
+    PUBLISHERS</h5>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="pageii"></a>[pg ii]</span>
+
+    <h4>1902</h4>
+
+    <p>&nbsp;</p>
+
+    <h5>Stanhope Press<br>
+    F. H. GILSON COMPANY<br>
+    BOSTON, U.S.A.</h5>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="pageiii"></a>[pg iii]</span>
+
+    <h3>EDITORIAL BOARD</h3>
+
+    <div class="poem">
+        <div class="stanza">
+            <p><b>THOMAS BAILEY ALDRICH, Editor-in-chief,</b></p>
+
+            <p>Author, poet, former editor <i>Atlantic Monthly,</i>
+            Boston, Mass.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>The HON. JOHN D. LONG,</b></p>
+
+            <p>Secretary of the United States Navy, Boston.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>HAMILTON WRIGHT MABIE, LL.D.,</b></p>
+
+            <p>Author, literarian, associate editor <i>The
+            Outlook</i>, New York.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>ERNEST THOMPSON SETON,</b></p>
+
+            <p>Artist, author, New York.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>JOHN TOWNSEND TROWBRIDGE,</b></p>
+
+            <p>Author, poet, and editor, Arlington, Mass.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>The REVEREND CYRUS TOWNSEND BRADY,</b></p>
+
+            <p>Archdeacon, author, Philadelphia.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>JOEL CHANDLER HARRIS,</b></p>
+
+            <p>Humorous writer, Atlanta, Ga.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>MARY HARTWELL CATHERWOOD,</b></p>
+
+            <p>Historical novelist, Chicago.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>LAURA E. RICHARDS,</b></p>
+
+            <p>Author, Gardiner, Me.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>ROSWELL FIELD,</b></p>
+
+            <p>Author, editor <i>The Evening Post</i>,
+            Chicago.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>TUDOR JENKS,</b></p>
+
+            <p>Author, associate editor <i>Saint Nicholas</i>, New
+            York.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>GEORGE A. HENTY,</b></p>
+
+            <p>Traveller, author, London, England.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>KIRK MUNROE,</b></p>
+
+            <p>Writer of stories for boys, Cocoanut Grove, Fla.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>EDITH M. THOMAS,</b></p>
+
+            <p>Poet, West New Brighton, N.Y.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>CAROLINE TICKNOR,</b></p>
+
+            <p>Author, editor, Boston.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>NATHAN HASKELL DOLE,</b></p>
+
+            <p>Author, translator, literary editor <i>Current
+            History</i>, Boston.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>WILLIAM RAINEY HARPER, D.D., LL.D.,</b></p>
+
+            <p>President Chicago University.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>DAVID STARR JORDAN, M.D., LL.D.,</b></p>
+
+            <p>President Leland Stanford Junior University,
+            naturalist, writer,</p>
+
+            <p>Stanford University, Cal.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>CHARLES ELIOT NORTON, A.M., LL.D., etc.,</b></p>
+
+            <p>Scholar, author, Emeritus Professor of Art at
+            Harvard University.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>HENRY VAN DYKE, D.D., LL.D.,</b></p>
+
+            <p>Clergyman, author, Professor Princeton
+            University.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>The REVEREND THOMAS J. SHAHAN,</b></p>
+
+            <p>Dean of the Faculty of Divinity, Professor of Early
+            Ecclesiastical</p>
+
+            <p>History, Catholic University, Washington, D.C.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>WILLIAM P. TRENT,</b></p>
+
+            <p>Author, editor, Professor of English Literature,
+            Columbia University,</p>
+
+            <p>New York City.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>EDWARD SINGLETON HOLDEN, A.M., LL.D.,</b></p>
+
+            <p>Ex-president University of California, astronomer,
+            author,</p>
+
+            <p>U.S. Military Academy, West Point.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>EDWIN ERLE SPARKS,</b></p>
+
+            <p>Professor of American History, Chicago
+            University.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>The VERY REV. GEORGE M. GRANT, D.D.,
+            LL.D.,</b></p>
+
+            <p>Educator, author, vice-principal Queen's College,
+            Kingston, Ont.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>BARONESS VON BULOW,</b></p>
+
+            <p>Educator, author, Dresden, Germany.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>ABBIE FARWELL BROWN,</b></p>
+
+            <p>Author, Boston.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>CHARLES WELSH, Managing Editor,</b></p>
+
+            <p>Author, lecturer, editor, Winthrop Highlands,
+            Mass.</p>
+        </div>
+    </div><span class="pagenum"><a id="pageiv"></a>[pg iv]</span>
+
+    <p>&nbsp;</p>
+
+    <h3>LIST OF VOLUMES</h3>
+
+    <div class="poem">
+        <div class="stanza">
+            <p class="i16">VOLUME I.</p>
+
+            <p><b>THE STORY TELLER</b></p>
+
+            <p class="i4">Edited by CHARLES ELIOT NORTON</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME II.</p>
+
+            <p><b>THE MERRY MAKER</b></p>
+
+            <p class="i4">Edited by JOEL CHANDLER HARRIS</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME III.</p>
+
+            <p><b>FAMOUS FAIRY TALES</b></p>
+
+            <p class="i4">Edited by ROSWELL FIELD</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME IV.</p>
+
+            <p><b>TALES OF FANTASY</b></p>
+
+            <p class="i4">Edited by TUDOR JENKS</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME V.</p>
+
+            <p><b>MYTHS AND LEGENDS</b></p>
+
+            <p class="i4">Edited by THOMAS J. SHAHAN</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME VI.</p>
+
+            <p><b>THE ANIMAL STORY BOOK</b></p>
+
+            <p class="i4">Edited by ERNEST THOMPSON SETON</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME VII.</p>
+
+            <p><b>SCHOOL AND COLLEGE DAYS</b></p>
+
+            <p class="i4">Edited by KIRK MUNROE and MARY HARTWELL
+            CATHERWOOD</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME VIII.</p>
+
+            <p><b>BOOK OF ADVENTURE</b></p>
+
+            <p class="i4">Edited by NATHAN HASKELL DOLE</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME IX.</p>
+
+            <p><b>FAMOUS EXPLORERS</b></p>
+
+            <p class="i4">Edited by EDWIN ERLE SPARKS</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME X.</p>
+
+            <p><b>BRAVE DEEDS</b></p>
+
+            <p class="i4">Edited by JOHN TOWNSEND TROWBRIDGE</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME XI.</p>
+
+            <p><b>WONDERS OF EARTH, SEA AND SKY</b></p>
+
+            <p class="i4">Edited by EDWARD SINGLETON HOLDEN</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME XII.</p>
+
+            <p><b>FAMOUS TRAVELS</b></p>
+
+            <p class="i4">Edited by GEORGE A. HENTY</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME XIII.</p>
+
+            <p><b>SEA STORIES</b></p>
+
+            <p class="i4">Edited by CYRUS TOWNSEND BRADY</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME XIV.</p>
+
+            <p><b>A BOOK OF NATURAL HISTORY</b></p>
+
+            <p class="i4">Edited by DAVID STARR JORDAN</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME XV.</p>
+
+            <p><b>HISTORIC SCENES IN FICTION</b></p>
+
+            <p class="i4">Edited by HENRY VAN DYKE</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME XVI.</p>
+
+            <p><b>FAMOUS BATTLES BY LAND AND SEA</b></p>
+
+            <p class="i4">Edited by JOHN D. LONG</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME XVII.</p>
+
+            <p><b>MEN WHO HAVE RISEN</b></p>
+
+            <p class="i4">Edited by HAMILTON WRIGHT MABIE.</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME XVIII.</p>
+
+            <p><b>BOOK OF PATRIOTISM</b></p>
+
+            <p class="i4">Edited by</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME XIX.</p>
+
+            <p><b>LEADERS OF MEN, OR HISTORY TOLD IN
+            BIOGRAPHY</b></p>
+
+            <p class="i4">Edited by WILLIAM RAINEY HARPER</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME XX.</p>
+
+            <p><b>FAMOUS POEMS</b></p>Selected by THOMAS BAILEY
+            ALDRICH, with Poetical Foreword by EDITH M. THOMAS.
+        </div>
+    </div>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="pagevi"></a>[pg vi]</span>
+
+    <div class="figcenter"
+         style="width:100%;">
+        <a href="images/047.jpg"><img width="300"
+             src="images/047sm.jpg"
+             alt="A GEYSER"></a><br>
+        A GEYSER
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="pagevii"></a>[pg vii]</span>
+
+    <h4><i>Young Folks' Library in Twenty Volumes</i><br>
+     <i>Thomas Bailey Aldrich, Editor-in-Chief</i></h4>
+
+    <p>&nbsp;</p>
+
+    <p class="center xbig">WONDERS</p>
+
+    <h4><span class="sc">of</span></h4>
+
+    <p class="center xbig">EARTH, SEA <span class="sc">and</span> SKY</p>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p>
+
+    <h4>EDITED BY</h4>
+
+    <h3>EDWARD SINGLETON HOLDEN</h3>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p>
+
+    <h4><i>VOLUME XI</i></h4>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p>
+
+    <div class="figcenter"
+         style="width:200px;">
+        <img width="200"
+             src="images/vii.png"
+             alt="title page decoration">
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p>
+
+    <h5>BOSTON<br>
+    HALL AND LOCKE COMPANY<br>
+    PUBLISHERS</h5>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="pageviii"></a>[pg viii]</span>
+
+    <h4>1902</h4>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p>
+
+    <h5><b>Stanhope Press</b><br>
+    P.H. GILSON COMPANY<br>
+    BOSTON, U.S.A.</h5>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="pageix"></a>[pg ix]</span>
+
+    <h2>CONTENTS</h2>
+
+    <div class="sc">
+        <div class="poem">
+            <div class="stanza"></div>
+
+            <div class="stanza">
+                <p>List of Illustrations <a href=
+                "#pagexi">&nbsp;&nbsp;xi</a></p>
+            </div>
+
+            <div class="stanza">
+                <p>The Marvels of Nature <a href=
+                "#pagexiii">&nbsp;&nbsp;xiii</a></p>
+
+                <p class="i4">By Professor E.S. Holden.</p>
+            </div>
+
+            <div class="stanza">
+                <p>what The Earth's Crust is Made of <a href=
+                "#page1">&nbsp;&nbsp;1</a></p>
+
+                <p class="i4">by Agnes Giberne.</p>
+            </div>
+
+            <div class="stanza">
+                <p>America The Old World <a href=
+                "#page45">&nbsp;&nbsp;45</a></p>
+
+                <p class="i4">By Louis Agassiz.</p>
+            </div>
+
+            <div class="stanza">
+                <p>Some Records of the Rocks <a href=
+                "#page77">&nbsp;&nbsp;77</a></p>
+
+                <p class="i4">By N.S. Shaler.</p>
+            </div>
+
+            <div class="stanza">
+                <p>The Pitch Lake in the West Indies <a href=
+                "#page97">&nbsp;&nbsp;97</a></p>
+
+                <p class="i4">By Charles Kingsley.</p>
+            </div>
+
+            <div class="stanza">
+                <p>A Stalagmite Cave <a href=
+                "#page111">&nbsp;&nbsp;111</a></p>
+
+                <p class="i4">By Sir C. Wyville Thomson.</p>
+            </div>
+
+            <div class="stanza">
+                <p>The Big Trees of California <a href=
+                "#page119">&nbsp;&nbsp;119</a></p>
+
+                <p class="i4">by Alfred Russel Wallace.</p>
+            </div>
+
+            <div class="stanza">
+                <p>what is Evolution? <a href=
+                "#page127">&nbsp;&nbsp;127</a></p>
+
+                <p class="i4">By Professor Edward S. Holden.</p>
+            </div>
+
+            <div class="stanza">
+                <p>How the Soil is Made <a href=
+                "#page135">&nbsp;&nbsp;135</a></p>
+
+                <p class="i4">By Charles Darwin.</p>
+            </div>
+
+            <div class="stanza">
+                <p>zoölogical Myths <a href=
+                "#page143">&nbsp;&nbsp;143</a></p>
+
+                <p class="i4">By Andrew Wilson.</p>
+            </div>
+
+            <div class="stanza">
+                <p>On a Piece of Chalk <a href=
+                "#page171">&nbsp;&nbsp;171</a></p>
+
+                <p class="i4">By T.H. Huxley.</p>
+            </div>
+
+            <div class="stanza">
+                <p>A Bit of Sponge <a href=
+                "#page205">&nbsp;&nbsp;205</a></p>
+
+                <p class="i4">BY A. WILSON.</p>
+            </div>
+
+            <div class="stanza">
+                <p>The Greatest Sea-Wave Ever Known <a href=
+                "#page211">&nbsp;&nbsp;211</a></p>
+
+                <p class="i4">By R.A. Proctor.</p><span class=
+                "pagenum"><a id="pagex"></a>[pg x]</span>
+            </div>
+
+            <div class="stanza">
+                <p>The Phosphorescent Sea <a href=
+                "#page228">&nbsp;&nbsp;228</a></p>
+
+                <p class="i4">By W.S. Dallas.</p>
+            </div>
+
+            <div class="stanza">
+                <p>COMETS, <a href=
+                "#page251">&nbsp;&nbsp;251</a></p>
+
+                <p class="i4">By Camille Flammarion.</p>
+            </div>
+
+            <div class="stanza">
+                <p>The Total Solar Eclipse of 1883 <a href=
+                "#page261">&nbsp;&nbsp;261</a></p>
+
+                <p class="i4">By E.S. Holden.</p>
+            </div>
+
+            <div class="stanza">
+                <p>Halos&mdash;Parhelia&mdash;the Spectre of the
+                Brocken, etc. <a href=
+                "#page268">&nbsp;&nbsp;268</a></p>
+
+                <p class="i4">By Camille Flammarion.</p>
+            </div>
+
+            <div class="stanza">
+                <p>The Planet Venus <a href=
+                "#page282">&nbsp;&nbsp;282</a></p>
+
+                <p class="i4">By Agnes M. Clerke.</p>
+            </div>
+
+            <div class="stanza">
+                <p>The Stars <a href=
+                "#page296">&nbsp;&nbsp;296</a></p>
+
+                <p class="i4">By Sir R.S. Ball.</p>
+            </div>
+
+            <div class="stanza">
+                <p>Rain and Snow <a href=
+                "#page342">&nbsp;&nbsp;342</a></p>
+
+                <p class="i4">By John Tyndall.</p>
+            </div>
+
+            <div class="stanza">
+                <p>The Organic World <a href=
+                "#page357">&nbsp;&nbsp;357</a></p>
+
+                <p class="i4">By St. George Mivart.</p>
+            </div>
+
+            <div class="stanza">
+                <p>Inhabitants of My Pool <a href=
+                "#page366">&nbsp;&nbsp;366</a></p>
+
+                <p class="i4">By Arabella B. Buckley.</p>
+            </div>
+
+            <div class="stanza">
+                <p>Biographical Notes <a href=
+                "#page387">&nbsp;&nbsp;387</a></p>
+            </div>
+
+            <div class="stanza">
+                <p>Suggestions for Supplementary Reading
+                   <a href="#page389">&nbsp;&nbsp;389</a></p>
+            </div>
+        </div>
+    </div>
+
+    <h5>NOTE.</h5>
+
+    <p>The publishers' acknowledgments are due to Messrs. Houghton,
+    Mifflin &amp; Co., for permission to use "America and the Old
+    World," by L. Agassiz; to Messrs. D.C. Heath &amp; Co. for
+    permission to use "Some Records of the Rocks," by Professor
+    N.S. Shaler; and to Professor E.S. Holden for permission to use
+    "What is Evolution?" and "An Astronomer's Voyage to Fairy
+    Land."</p>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="pagexi"></a>[pg xi]</span>
+
+    <h2>LIST OF COLORED ILLUSTRATIONS</h2>
+    <hr class="short">
+
+    <div class="poem">
+        <div class="stanza">
+            <p><span class="sc">A Geyser.</span>&nbsp;&nbsp;
+            <a href="#pagevi"><i>Frontispiece,</i></a> <i>See
+            Page</i> <a href="#page47">&nbsp;&nbsp;47</a></p>
+        </div>
+
+        <div class="stanza">
+            <p class="sc">View in a Cañon, <a href=
+            "#page12">&nbsp;&nbsp;12</a></p>
+        </div>
+
+        <div class="stanza">
+            <p class="sc">A Volcano, <a href=
+            "#page48">&nbsp;&nbsp;48</a></p>
+        </div>
+
+        <div class="stanza">
+            <p class="sc">A Stalagmite Cave, <a href=
+            "#page117">&nbsp;&nbsp;117</a></p>
+        </div>
+
+        <div class="stanza">
+            <p class="sc">Where Sponges Grow, <a href=
+            "#page209">&nbsp;&nbsp;209</a></p>
+        </div>
+
+        <div class="stanza">
+            <p class="sc">A Comet, <a href=
+            "#page254">&nbsp;&nbsp;254</a></p>
+        </div>
+
+        <div class="stanza">
+            <p class="sc">The Spectre Of The Brocken, <a href=
+            "#page272">&nbsp;&nbsp;272</a></p>
+        </div>
+    </div>
+    <hr class="short">
+
+    <p class="sc">And One Hundred and Sixty-four Black and White
+    Illustrations in the Text.</p>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="pagexiii"></a>[pg xiii]</span>
+
+    <h2>THE MARVELS OF NATURE</h2>
+
+    <h4 class="sc">By</h4>
+
+    <h3>EDWARD S. HOLDEN, M.A., Sc.D. LL.D.</h3>
+    <hr class="short">
+
+    <p>The Earth, the Sea, the Sky, and their wonders&mdash;these
+    are the themes of this volume. The volume is so small, and the
+    theme so vast! Men have lived on the earth for hundreds of thousands
+    of years; and its wonders have increased, not diminished,
+    with their experience.</p>
+
+    <p>To our barbarous ancestors of centuries ago, all was
+    mystery&mdash;the thunder, the rainbow, the growing corn, the
+    ocean, the stars. Gradually and by slow steps they learned to
+    house themselves in trees, in caves, in huts, in houses; to
+    find a sure supply of food; to provide a stock of serviceable
+    clothing. The arts of life were born; tools were invented; the
+    priceless boon of fire was received; tribes and clans united
+    for defence; some measure of security and comfort was
+    attained.</p>
+
+    <p>With security and comfort came leisure; and the mind of
+    early Man began curiously to inquire the meaning of the
+    mysteries with which he was surrounded. That curious inquiry
+    was the birth of Science. Art was born when some far-away
+    ancestor, in an idle hour, <span class="pagenum"><a name=
+    "pagexiv"
+       id="pagexiv"></a>[pg xiv]</span> scratched on a bone the
+       drawing of two of his reindeer fighting, or carved on the
+       walls of his cave the image of the mammoth that he had but
+       lately slain with his spear and arrows.</p>
+
+    <p>In a mind that is completely ignorant there is no wonder.
+    Wonder is the child of knowledge&mdash;of partial and imperfect
+    knowledge, to be sure, but still, of knowledge. The very first
+    step in Science is to make an inventory of external Nature (and
+    by and by of the faculties of the mind that thinks). The second
+    step is to catalogue similar appearances together. It is a much
+    higher flight to seek the causes of likenesses thus
+    discovered.</p>
+
+    <p>A few of the chapters of this volume are items in a mere
+    catalogue of wonders, and deserve their place by accurate and
+    eloquent description. Most of them, however, represent higher
+    stages of insight. In the latter, Nature is viewed not only
+    with the eye of the observer, but also with the mind's eye,
+    curious to discover the reasons for things seen. The most
+    penetrating inward inquiry accompanies the acutest external
+    observation in such chapters as those of Darwin and Huxley,
+    here reprinted.</p>
+
+    <p>Now, the point not to be overlooked is this: to Darwin and
+    Huxley, as to their remote and uncultured ancestors, the
+    World&mdash;the Earth, the Sea, the Sky&mdash;is full of
+    wonders and of mysteries, but the wonders are of a higher
+    order. The problems of the thunder <span class=
+    "pagenum"><a id="pagexv"></a>[pg xv]</span> and of the rainbow as they
+       presented themselves to the men of a thousand generations
+       ago, have been fully solved: but the questions; what is the
+       veritable nature of electricity, exactly how does it differ
+       from light, are still unanswered. And what are simple
+       problems like these to the questions: what is love; why do
+       we feel a sympathy with this person, an antipathy for that;
+       and others of the sort? Science has made almost infinite
+       advances since pre-historic man first felt the feeble
+       current of intellectual curiosity amid his awe of the storm;
+       it has still to grow almost infinitely before anything like
+       a complete explanation even of external Nature is
+       achieved.</p>
+
+    <p>Suppose that, at some future day, all physical and
+    mechanical laws should be found to be direct consequences of a
+    single majestic law, just as all the motions of the planets are
+    (but&mdash;are they?) the direct results of the single law of
+    gravitation. Gravitation will, probably, soon be explained in
+    terms of some remoter cause, but the reason of that single and
+    ultimate law of the universe which we have imagined would still
+    remain unknown. Human knowledge will always have limits, and
+    beyond those limits there will always be room for mystery and
+    wonder. A complete and exhaustive explanation of the world is
+    inconceivable, so long as human powers and capacities remain at
+    all as they now are.</p>
+
+    <p>It is important to emphasize such truths, especially
+    <span class="pagenum"><a id="pagexvi"></a>[pg xvi]</span> in a book addressed to the
+       young. When a lad hears for the first time that an
+       astronomer, by a simple pointing of his spectroscope, can
+       determine with what velocity a star is approaching the
+       earth, or receding from it, or when he hears that the very
+       shape of the revolving masses of certain stars can be
+       calculated from simple measures of the sort, he is apt to
+       conclude that Science, which has made such astounding
+       advances since the days of Galileo and Newton, must
+       eventually reach a complete explanation of the entire
+       universe. The conclusion is not unnatural, but it is not
+       correct. There are limits beyond which Science, in this
+       sense, cannot go. Its scope is limited. Beyond its limits
+       there are problems that it cannot solve, mysteries that it
+       cannot explain.</p>
+
+    <p>At the present moment, for example, the nature of Force is
+    unknown. A weight released from the hand drops to the earth.
+    Exactly what is the nature of the force with which the earth
+    attracts it? We do not know, but it so happens that it is more
+    than likely that an explanation will be reached in our own day.
+    Gravity will be explained in terms of some more general forces.
+    The mystery will be pushed back another step, and yet another
+    and another. But the progress is not indefinite. If all the
+    mechanical actions of the entire universe were to be formulated
+    as the results of a single law or cause, the cause of that
+    cause would be still to seek, as has been
+          said.</p><span class="pagenum"><a id="pagexvii"></a>[pg xvii]</span>
+
+    <p>We have every right to exult in the amazing achievements of
+    Science; but we have not understood them until we realize that
+    the universe of Science has strict limits, within which all its
+    conquests must necessarily be confined. Humility, and not
+    pride, is the final lesson of scientific work and study.</p>
+    <hr>
+
+    <p>The choice of the selections printed in this volume has been
+    necessarily limited by many hampering conditions, that of mere
+    space being one of the most harassing. Each of the chapters
+    might readily be expanded into a volume. Volumes might be added
+    on topics almost untouched here. It has been necessary to pass
+    over almost without notice matters of surpassing interest and
+    importance: Electricity and its wonderful and new applications;
+    the new Biology, with its views upon such fundamental questions
+    as the origins of life and death; modern Astronomy, with its
+    far-reaching pronouncements upon the fate of universes. All
+    these can only be touched lightly, if at all. It is the chief
+    purpose of this volume to point the way towards the most modern
+    and the greatest conclusions of Science, and to lay foundations
+    upon which the reading of a life-time can be laid.</p>
+
+    <div class="figright"
+         style="width:300px;">
+        <img width="300"
+             src="images/xvii.png"
+             alt="signature">
+    </div><br>
+
+    <p><span class="sc">United States Military Academy,<br>
+     &nbsp;&nbsp;&nbsp;&nbsp;West Point,</span> <i>January 1,
+    1902</i>.</p>
+    <hr>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="page1"></a>[pg 1]</span>
+
+    <p class="xbig center">WONDERS OF EARTH, SEA, AND SKY</p>
+    <hr class="short">
+
+    <h2>WHAT THE EARTH'S CRUST IS MADE OF</h2>
+
+    <h4 class="sc">(From The World's Foundations.)</h4>
+
+    <h3><span class="sc">By</span> AGNES GIBERNE.</h3>
+    <hr class="short">
+
+    <blockquote>
+        <p>"Stand still and consider the wondrous works of
+        God."</p>
+    </blockquote>
+
+    <div class="figleft"
+         style="width:200px">
+        <a href="images/001.png"><img width="200"
+             src="images/001.png"
+             alt="globe"></a>
+    </div>
+
+    <p>What is the earth made of&mdash;this round earth upon which
+    we human beings live and move?</p>
+
+    <p>A question more easily asked than answered, as regards a
+    very large portion of it. For the earth is a huge ball nearly
+    eight thousand miles in diameter, and we who dwell on the
+    outside have no means of getting down more than a very little
+    way below the surface. So it is quite impossible for us to
+    speak positively as to the inside of the earth, and what it is
+    made of. Some people believe the earth's inside to be hard and
+    solid, while others believe it to be one <span class=
+    "pagenum"><a id="page2"></a>[pg 2]</span> enormous lake or furnace of
+       fiery melted rock. But nobody really knows.</p>
+
+    <p>This outside crust has been reckoned to be of many different
+    thicknesses. One man will say it is ten miles thick, and
+    another will rate it at four hundred miles. So far as regards
+    man's knowledge of it, gained from mining, from boring, from
+    examination of rocks, and from reasoning out all that may be
+    learned from these observations, we shall allow an ample margin
+    if we count the field of geology to extend some twenty miles
+    downwards from the highest mountain-tops. Beyond this we find
+    ourselves in a land of darkness and conjecture.</p>
+
+    <p>Twenty miles is only one four-hundredth part of the earth's
+    diameter&mdash;a mere thin shell over a massive globe. If the
+    earth were brought down in size to an ordinary large school
+    globe, a piece of rough brown paper covering it might well
+    represent the thickness of this earth-crust, with which the
+    science of geology has to do. And the whole of the globe, this
+    earth of ours, is but one tiny planet in the great Solar
+    System. And the centre of that Solar System, the blazing sun,
+    though equal in size to more than a million earths, is yet
+    himself but one star amid millions of twinkling stars,
+    scattered broadcast through the universe. So it would seem at
+    first sight that the field of geology is a small field compared
+    with that of astronomy....</p>
+
+    <p>With regard to the great bulk of the globe little can be
+    said. Very probably it is formed through and through of the
+    same materials as the crust. This we do not know. Neither can
+    we tell, even if it be so formed, whether the said materials
+    are solid and cold <span class="pagenum"><a id="page3"></a>[pg 3]</span> like the outside crust, or
+       whether they are liquid with heat. The belief has been long
+       and widely held that the whole inside of the earth is one
+       vast lake or furnace of melted fiery-hot material, with only
+       a thin cooled crust covering it. Some in the present day are
+       inclined to question this, and hold rather that the earth is
+       solid and cold throughout, though with large lakes of liquid
+       fire here and there, under or in her crust, from which our
+       volcanoes are fed....</p>
+
+    <p>The materials of which the crust is made are many and
+    various; yet, generally speaking, they may all be classed under
+    one simple word, and that word is&mdash;<i>Rock</i>.</p>
+
+    <p>It must be understood that, when we talk of rock in this
+    geological sense, we do not only mean hard and solid stone, as
+    in common conversation. Rock may be changed by heat into a
+    liquid or "molten" state, as ice is changed by heat to water.
+    Liquid rock may be changed by yet greater heat to vapor, as
+    water is changed to steam, only we have in a common way no such
+    heat at command as would be needed to effect this. Rock may be
+    hard or soft. Rock maybe chalky, clayey, or sandy. Rock may be
+    so close-grained that strong force is needed to break it; or it
+    may be so porous&mdash;so full of tiny holes&mdash;that water
+    will drain through it; or it may be crushed and crumbled into
+    loose grains, among which you can pass your fingers.</p>
+
+    <p>The cliffs above our beaches are rock; the sand upon our
+    seashore is rock; the clay used in brick-making is rock; the
+    limestone of the quarry is rock; the marble of which our
+    mantel-pieces are made is rock. The soft sandstone of South
+    Devon, and the hard granite of the <span class=
+    "pagenum"><a id="page4"></a>[pg 4]</span> north of Scotland, are alike
+       rock. The pebbles in the road are rock; the very mould in
+       our gardens is largely composed of crumbled rock. So the
+       word in its geological sense is a word of wide meaning.</p>
+
+    <p>Now the business of the geologist is to read the history of
+    the past in these rocks of which the earth's crust is made.
+    This may seem a singular thing to do, and I can assure you it
+    is not an easy task.</p>
+
+    <p>For, to begin with, the history itself is written in a
+    strange language, a language which man is only just beginning
+    to spell out and understand. And this is only half the
+    difficulty with which we have to struggle.</p>
+
+    <p>If a large and learned book were put before you and you were
+    set to read it through, you would perhaps, have no
+    insurmountable difficulty, with patience and perseverance, in
+    mastering its meaning.</p>
+
+    <p>But how if the book were first chopped up into pieces, if
+    part of it were flung away out of reach, if part of it were
+    crushed into a pulp, if the numbering of the pages were in many
+    places lost, if the whole were mixed up in confusion, and if
+    <i>then</i> you were desired to sort, and arrange, and study
+    the volume?</p>
+
+    <p>Picture to yourself what sort of a task this would be, and
+    you will have some idea of the labors of the patient
+    geologist.</p>
+
+    <p>Rocks may be divided into several kinds or classes. For the
+    present moment it will be enough to consider the two grand
+    divisions&mdash;<i>Stratified rocks</i> and <i>Unstratified
+    rocks</i>.</p>
+
+    <p>Unstratified rocks are those which were once, at a time more
+    or less distant, in a melted state from intense heat, and which
+    have since cooled into a half <i>crystallized</i>
+          <span class="pagenum"><a id="page5"></a>[pg 5]</span> state; much the same as water,
+       when growing colder, cools and crystallizes into ice.
+       Strictly speaking, ice is rock, just as much as granite and
+       sandstone are rock. Water itself is of the nature of rock,
+       only as we commonly know it in the liquid state we do not
+       commonly call it so.</p>
+
+    <div class="figright"
+         style="width:400px;">
+        <a href="images/005.png"><img width="400"
+             src="images/005.png"
+             alt=
+             "UNSTRATIFIED ROCK.&mdash;A VOLCANIC BLOCK."></a><br>
+        UNSTRATIFIED ROCK.&mdash;A VOLCANIC BLOCK.
+    </div>
+
+    <p>"Crystallization" means those particular forms or shapes in
+    which the particles of a liquid arrange themselves, as that
+    liquid hardens into a solid&mdash;in other words, as it
+    freezes. Granite, iron, marble, are frozen substances, just as
+    truly as ice is a frozen substance; for with greater heat they
+    would all become liquid like water. When a liquid freezes,
+    there are always crystals formed, though these are not always
+    visible without the help of a microscope. Also the crystals are
+    of different shapes with different substances.</p>
+
+    <p>If you examine the surface of a puddle or pond, when a thin
+    covering of ice is beginning to form, you will be able to see
+    plainly the delicate sharp needle-like forms of the ice
+    crystals. Break a piece of ice, and you will find that it will
+    not easily break just in any way that you may choose, but it
+    will only split along the lines of these needle-like crystals.
+    This particular mode of splitting in a crystallized rock is
+    called the <i>cleavage</i> of that rock.</p>
+
+    <p>Crystallization may take place either slowly or
+          <span class="pagenum"><a id="page6"></a>[pg 6]</span> rapidly, and either in the open
+       air or far below ground. The lava from a volcano is an
+       example of rock which has crystallized rapidly in the open
+       air; and granite is an example of rock which has
+       crystallized slowly underground beneath great pressure.</p>
+
+    <p>Stratified rocks, on the contrary, which make up a very
+    large part of the earth's crust, are not crystallized. Instead
+    of having cooled from a liquid into a solid state, they have
+    been slowly <i>built up</i>, bit by bit and grain upon grain,
+    into their present form, through long ages of the world's
+    history. The materials of which they are made were probably
+    once, long, long ago, the crumblings from granite and other
+    crystallized rocks, but they show now no signs of
+    crystallization.</p>
+
+    <div class="figleft"
+         style="width:300px">
+        <a href="images/006.png"><img width="300"
+             src="images/006.png"
+             alt="SECTION OF STRATIFIED ROCKS."></a><br>
+        SECTION OF STRATIFIED ROCKS.
+
+        <p><i>a.</i> Conglomerate. <i>b.</i> Pebbly Sandstone,
+        <i>c.</i> Thin-bedded Sandstone, <i>d.</i> Shelly
+        Sandstone, <i>e.</i> Shale. <i>f.</i> Limestone.</p>
+    </div>
+
+    <p>They are called "stratified" because they are in themselves
+    made up of distinct layers, and also because they lie thus one
+    upon another in layers, or <i>strata</i>, just as the leaves of
+    a book lie, or as the bricks of a house are placed.</p>
+
+    <p>Throughout the greater part of Europe, of Asia, of Africa,
+    of North and South America, of Australia, these rocks are to be
+    found, stretching over hundreds <span class=
+       "pagenum"><a id="page7"></a>[pg 7]</span> of miles together, north,
+       south, east, and west, extending up to the tops of some of
+       the earth's highest mountains, reaching down deep into the
+       earth's crust. In many parts if you could dig straight
+       downwards through the earth for thousands of feet, you would
+       come to layer after layer of these stratified rocks, one
+       kind below another, some layers thick, some layers thin,
+       here a stratum of gravel, there a stratum of sandstone, here
+       a stratum of coal, there a stratum of clay.</p>
+
+    <p>But how, when, where, did the building up of all these
+    rock-layers take place?</p>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/007.png"><img width="600"
+             src="images/007.png"
+             alt=
+             "THE BEACH IN THE FOREGROUND IS A ROCKY SHELF,"></a>
+
+        <p>THE BEACH IN THE FOREGROUND IS A ROCKY SHELF, THE
+        REMNANT OF THE CLIFF WHICH ONCE EXTENDED OUT TO THE
+        ISLAND.</p>
+    </div>
+
+    <p>People are rather apt to think of land and water on the
+    earth as if they were fixed in one changeless form,&mdash;as if
+    every continent and every island were of exactly the same shape
+    and size now that it always has been and always will
+    be.</p><span class="pagenum"><a id="page8"></a>[pg 8]</span>
+
+    <p>Yet nothing can be further from the truth. The earth-crust
+    is a scene of perpetual change, of perpetual struggle, of
+    perpetual building up, of perpetual wearing away.</p>
+
+    <p>The work may go on slowly, but it does go on. The sea is
+    always fighting against the land, beating down her cliffs,
+    eating into her shores, swallowing bit by bit of solid earth;
+    and rain and frost and inland streams are always busily at
+    work, helping the ocean in her work of destruction. Year by
+    year and century by century it continues. Not a country in the
+    world which is bordered by the open sea has precisely the same
+    coast-line that it had one hundred years ago; not a land in the
+    world but parts each century with masses of its material,
+    washed piecemeal away into the ocean.</p>
+
+    <p>Is this hard to believe? Look at the crumbling cliffs around
+    old England's shores. See the effect upon the beach of one
+    night's fierce storm. Mark the pathway on the cliff, how it
+    seems to have crept so near the edge that here and there it is
+    scarcely safe to tread; and very soon, as we know, it will
+    become impassable. Just from a mere accident, of
+    course,&mdash;the breaking away of some of the earth, loosened
+    by rain and frost and wind. But this is an accident which
+    happens daily in hundreds of places around the shores.</p>
+
+    <p>Leaving the ocean, look now at this river in our
+    neighborhood, and see the slight muddiness which seems to color
+    its waters. What from? Only a little earth and sand carried off
+    from the banks as it flowed,&mdash;very unimportant and small
+    in quantity, doubtless, just at this moment and just at this
+    spot. But what of that little going on week after week, and
+    century <span class="pagenum"><a id="page9"></a>[pg 9]</span> after century, throughout the
+       whole course of the river, and throughout the whole course
+       of every river and rivulet in our whole country and in every
+       other country. A vast amount of material must every year be
+       thus torn from the land and given to the ocean. For the
+       land's loss here is the ocean's gain.</p>
+
+    <p>And, strange to say, we shall find that this same ocean, so
+    busily engaged with the help of its tributary rivers in pulling
+    down land, is no less busily engaged with their help in
+    building it up.</p>
+
+    <p>You have sometimes seen directions upon a vial of medicine
+    to "shake" before taking the dose. When you have so shaken the
+    bottle the clear liquid grows thick; and if you let it stand
+    for awhile the thickness goes off, and a fine grain-like or
+    dust-like substance settles down at the bottom&mdash;the
+    settlement or <i>sediment</i> of the medicine. The finer this
+    sediment, the slower it is in settling. If you were to keep the
+    liquid in gentle motion, the fine sediment would not settle
+    down at the bottom. With coarser and heavier grains the motion
+    would have to be quicker to keep them supported in the
+    water.</p>
+
+    <p>Now it is just the same thing with our rivers and streams.
+    Running water can support and carry along sand and earth, which
+    in still water would quickly sink to the bottom; and the more
+    rapid the movement of the water, the greater is the weight it
+    is able to bear.</p>
+
+    <p>This is plainly to be seen in the case of a mountain
+    torrent. As it foams fiercely through its rocky bed it bears
+    along, not only mud and sand and gravel, but stones and even
+    small rocks, grinding the latter roughly together till they are
+    gradually worn away, first to <span class="pagenum"><a name=
+    "page10"
+       id="page10"></a>[pg 10]</span> rounded pebbles, then to
+       sand, and finally to mud. The material thus swept away by a
+       stream, ground fine, and carried out to sea&mdash;part being
+       dropped by the way on the river-bed&mdash;is called
+       <i>detritus</i>, which simply means <i>worn-out</i>
+       material.</p>
+
+    <div class="figleft"
+         style="width:400px;">
+        <a href="images/010.png"><img width="400"
+             src="images/010.png"
+             alt="A MOUNTAIN TORRENT."></a><br>
+        A MOUNTAIN TORRENT.
+    </div>
+
+    <p>The tremendous carrying-power of a mountain torrent can
+    scarcely be realized by those who have not observed it for
+    themselves. I have seen a little mountain-stream swell in the
+    course of a heavy thunderstorm to such a torrent, brown and
+    turbid with earth torn from the mountainside, and sweeping
+    resistlessly along in its career a shower of stones and
+    rock-fragments. That which happens thus occasionally with many
+    streams is more or less the work all the year round of many
+    more.</p>
+
+    <p>As the torrent grows less rapid, lower down in its course,
+    it ceases to carry rocks and stones, though the grinding and
+    wearing away of stones upon the rocky bed continues, and coarse
+    gravel is borne still upon its <span class=
+       "pagenum"><a id="page11"></a>[pg 11]</span> waters. Presently the
+       widening stream, flowing yet more calmly, drops upon its bed
+       all such coarser gravel as is not worn away to fine earth,
+       but still bears on the lighter grains of sand. Next the
+       slackening speed makes even the sand too heavy a weight, and
+       that in turn falls to line the river-bed, while the now
+       broad and placid stream carries only the finer particles of
+       mud suspended in its waters. Soon it reaches the ocean, and
+       the flow being there checked by the incoming ocean-tide,
+       even the mud can no longer be held up, and it also sinks
+       slowly in the shallows near the shore, forming sometimes
+       broad mud-banks dangerous to the mariner.</p>
+
+    <p>This is the case only with smaller rivers. Where the stream
+    is stronger, the mud-banks are often formed much farther out at
+    sea; and more often still the river-detritus is carried away
+    and shed over the ocean-bed, beyond the reach of our ken. The
+    powerful rush of water in earth's greater streams bears
+    enormous masses of sand and mud each year far out into the
+    ocean, there dropping quietly the gravel, sand, and earth,
+    layer upon layer at the bottom of the sea. Thus pulling down
+    and building up go on ever side by side; and while land is the
+    theatre oftentimes of decay and loss, ocean is the theatre
+    oftentimes of renewal and gain.</p>
+
+    <p>Did you notice the word "sediment" used a few pages back
+    about the settlement at the bottom of a medicine-vial?</p>
+
+    <p>There is a second name given to the Stratified Rocks, of
+    which the earth's crust is so largely made up. They are called
+    also <i>Sedimentary Rocks</i>.</p><span class=
+       "pagenum"><a id="page12"></a>[pg 12]</span>
+
+    <p>The reason is simply this. The Stratified Rocks of the
+    present day were once upon a time made up out of the sediment
+    stolen first from land and then allowed to settle down on the
+    sea-bottom.</p>
+
+    <p>Long, long ago, the rivers, the streams, the ocean, were at
+    work, as they are now, carrying away rock and gravel, sand and
+    earth. Then, as now, all this material, borne upon the rivers,
+    washed to and fro by the ocean, settled down at the mouths of
+    rivers or at the bottom of the sea, into a sediment, one layer
+    forming over another, gradually built up through long ages. At
+    first it was only a soft, loose, sandy or muddy sediment, such
+    as you may see on the seashore, or in a mud-bank. But as the
+    thickness of the sediment increased, the weight of the layers
+    above gradually pressed the lower layers into firm hard rocks;
+    and still, as the work of building went on, these layers were,
+    in their turn, made solid by the increasing weight over them.
+    Certain chemical changes had also a share in the transformation
+    from soft mud to hard rock, which need not be here
+    considered.</p>
+
+    <p>All this has through thousands of years been going on. The
+    land is perpetually crumbling away; and fresh land under the
+    sea is being perpetually built up, from the very same materials
+    which the sea and the rivers have so mercilessly stolen from
+    continents and islands. This is the way, if geologists rightly
+    judge, in which a very large part of the enormous formations of
+    Stratified or Sedimentary Rocks have been made.</p>
+
+    <div class="figcenter"
+         style="width:300px;">
+        <a href="images/031.jpg"><img width="300"
+             src="images/031sm.jpg"
+             alt="VIEW IN A CANON."></a><br>
+        VIEW IN A CANON.
+    </div>
+
+    <p>So far is clear. But now we come to a difficulty.</p>
+
+    <p>The Stratified Rocks, of which a very large part of the
+    continents is made, appear to have been built up
+          <span class="pagenum"><a id="page13"></a>[pg 13]</span> slowly, layer upon layer, out
+       of the gravel, sand, and mud, washed away from the land and
+       dropped on the shore of the ocean.</p>
+
+    <div class="figright"
+         style="width:400px;">
+        <a href="images/013.png"><img width="400"
+             src="images/013.png"
+             alt=
+           "SEA CLIFFS SHOWING A SERIES OF STRATIFIED ROCKS."></a><br>
+        SEA CLIFFS SHOWING A SERIES OF STRATIFIED ROCKS.
+    </div>
+
+    <p>You may see these layers for yourself as you walk out into
+    the country. Look at the first piece of bluff rock you come
+    near, and observe the clear pencil-like markings of layer above
+    layer&mdash;not often indeed lying <i>flat</i>, one over
+    another, and this must be explained later, but however
+    irregularly slanting, still plainly visible. You can examine
+    these lines of stratification on the nearest cliff, the nearest
+    quarry, the nearest bare headland, in your neighborhood.</p>
+
+    <p>But how can this be? If all these stratified rocks are built
+    on the floor of the ocean out of material taken <i>from</i> the
+    land, how can we by any possibility find such rocks <i>upon</i>
+    the land? In the beds of rivers we might indeed expect to see
+    them, but surely nowhere else save under ocean waters.</p>
+
+    <p>Yet find them we do. Through England, through the two great
+    world-continents, they abound on every side. Thousands of miles
+    in unbroken succession are composed of such rocks.</p>
+
+    <p>Stand with me near the seashore, and let us look around.
+    Those white chalk cliffs&mdash;they, at least, are
+          <span class="pagenum"><a id="page14"></a>[pg 14]</span> not formed of sand or earth.
+       True, and the lines of stratification are in them very
+       indistinct, if seen at all; yet they too are built up of
+       sediment of a different kind, dropping upon ocean's floor.
+       See, however, in the rough sides of yonder bluff the
+       markings spoken of, fine lines running alongside of one
+       another, sometimes flat, sometimes bent or slanting, but
+       always giving the impression of layer piled upon layer. Yet
+       how can one for a moment suppose that the ocean-waters ever
+       rose so high?</p>
+
+    <p>Stay a moment. Look again at yonder white chalk cliff, and
+    observe a little way below the top a singular band of shingles,
+    squeezed into the cliff, as it were, with chalk below and earth
+    above.</p>
+
+    <p>That is believed to be an old sea-beach. Once upon a time
+    the waters of the sea are supposed to have washed those
+    shingles, as now they wash the shore near which we stand, and
+    all the white cliff must have lain then beneath the ocean.</p>
+
+    <p>Geologists were for a long while sorely puzzled to account
+    for these old sea-beaches, found high up in the cliffs around
+    our land in many different places.</p>
+
+    <p>They had at first a theory that the sea must once, in far
+    back ages, have been a great deal higher than it is now. But
+    this explanation only brought about fresh difficulties. It is
+    quite impossible that the level of the sea should be higher in
+    one part of the world than in another. If the sea around
+    England were then one or two hundred feet higher than it is
+    now, it must have been one or two hundred feet higher in every
+    part of the world where the ocean-waters have free flow. One is
+    rather puzzled to know where all the <span class=
+    "pagenum"><a id="page15"></a>[pg 15]</span> water could have come from,
+       for such a tremendous additional amount. Besides, in some
+       places remains of sea-animals are found in mountain heights,
+       as much as two or three thousand feet above the
+       sea-level&mdash;as, for instance, in Corsica. This very much
+       increases the difficulty of the above explanation.</p>
+
+    <p>So another theory was started instead, and this is now
+    generally supposed to be the true one. What if instead of the
+    whole ocean having been higher, parts of the land were lower?
+    England at one time, parts of Europe at another time, parts of
+    Asia and America at other times, may have slowly sunk beneath
+    the ocean, and after long remaining there have slowly risen
+    again.</p>
+
+    <p>This is by no means so wild a supposition as it may seem
+    when first heard, and as it doubtless did seem when first
+    proposed. For even in the present day these movements of the
+    solid crust of our earth are going on. The coasts of Sweden and
+    Finland have long been slowly and steadily rising out of the
+    sea, so that the waves can no longer reach so high upon those
+    shores as in years gone by they used to reach. In Greenland, on
+    the contrary, land has long been slowly and steadily sinking,
+    so that what used to be the shore now lies under the sea. Other
+    such risings and sinkings might be mentioned, as also many more
+    in connection with volcanoes and earthquakes, which are neither
+    slow nor steady, but sudden and violent.</p>
+
+    <p>So it becomes no impossible matter to believe that, in the
+    course of ages past, all those wide reaches of our continents
+    and islands, where sedimentary rocks are to be found, were each
+    in turn, at one time or another, <span class=
+       "pagenum"><a id="page16"></a>[pg 16]</span> during long periods, beneath
+       the rolling waters of the ocean....</p>
+    <hr>
+
+    <p>These built-up rocks are not only called "Stratified," and
+    "Sedimentary." They have also the name of <i>Aqueous Rock</i>,
+    from the Latin word <i>aqua, water</i>; because they are
+    believed to have been formed by the action of the water.</p>
+
+    <p>They have yet another and fourth title, which is,
+    <i>Fossiliferous Rocks</i>.</p>
+
+    <p>Fossils are the hardened remains of animals and vegetables
+    found in rocks. They are rarely, if ever, seen in unstratified
+    rocks; but many layers of stratified rocks abound in these
+    remains. Whole skeletons as well as single bones, whole
+    tree-trunks as well as single leaves, are found thus embedded
+    in rock-layers, where in ages past the animal or plant died and
+    found a grave. They exist by thousands in many parts of the
+    world, varying in size from the huge skeleton of the elephant
+    to the tiny shell of the microscopic animalcule.</p>
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/016.png"><img width="200"
+             src="images/016.png"
+             alt="FOSSIL OF CARBONIFEROUS FERN."></a><br>
+        FOSSIL OF CARBONIFEROUS FERN.
+    </div>
+
+    <p>Fossils differ greatly in kind. Sometimes the entire shell
+    or bone is changed into stone, losing all its animal substance,
+    but retaining its old outline and its natural markings.
+    Sometimes the fossil is merely the hardened impress of the
+    outside of a shell or leaf, which has dented its picture on
+    soft clay, and has itself disappeared, while the soft clay has
+    become rock, <span class="pagenum"><a id="page17"></a>[pg 17]</span> and the indented picture
+       remains fixed through after-centuries. Sometimes the fossil
+       is the cast of the inside of a shell; the said shell having
+       been filled with soft mud, which has taken its exact shape
+       and hardened, while the shell itself has vanished. The most
+       complete description of fossil is the first of these three
+       kinds. It is wonderfully shown sometimes in fossil wood,
+       where all the tiny cells and delicate fibres remain
+       distinctly marked as of old, only the whole woody substance
+       has changed into hard stone.</p>
+
+    <div class="figright"
+         style="width:380px;">
+        <a href="images/017-1.png"><img width="380"
+             src="images/017-1.png"
+             alt=
+           "FOOTPRINTS FROM TRIASSIC SANDSTONE OF CONNECTICUT."></a><br>
+        FOOTPRINTS FROM TRIASSIC SANDSTONE OF CONNECTICUT.
+    </div>
+
+    <p>But although the fossil remains of quadrupeds and other
+    land-animals are found in large quantities, their number is
+    small compared with the enormous number of fossil sea-shells
+    and sea-animals.</p>
+
+    <div class="figleft"
+         style="width:400px;">
+        <a href="images/017-2.png"><img width="400"
+             src="images/017-2.png"
+             alt="FOSSIL FOOTPRINTS."></a><br>
+        FOSSIL FOOTPRINTS.
+    </div>
+
+    <p>Land-animals can, as a rule, have been so preserved, only
+    when they have been drowned in ponds or rivers, or mired in
+    bogs and swamps, or overtaken by frost, or swept out to
+    sea.</p>
+
+    <p>Sea-animals, on the contrary, have been so preserved on land
+    whenever that land has been under the sea; and this appears to
+    have been the case, at one or another past age, with the
+    greater part of our present <span class="pagenum"><a name=
+    "page18"
+       id="page18"></a>[pg 18]</span> continents. These fossil
+       remains of sea-animals are discovered in all quarters of the
+       world, not only on the seashore but also far inland, not
+       only deep down underground but also high up on the tops of
+       lofty mountains&mdash;a plain proof that over the summits of
+       those mountains the ocean must once have rolled, and this
+       not for a brief space only, but through long periods of
+       time. And not on the mountain-summit only are these fossils
+       known to abound, but sometimes in layer below layer of the
+       mountain, from top to bottom, through thousands of feet of
+       rock.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/018.png"><img width="300"
+             src="images/018.png"
+             alt="FOSSIL SHELLS."></a><br>
+        FOSSIL SHELLS.
+    </div>
+
+    <p>This may well seem puzzling at first sight. Fossils of
+    sea-creatures on a mountain-top are startling enough; yet
+    hardly so startling as the thought of fossils <i>inside</i>
+    that mountain. How could they have found their way thither?</p>
+
+    <p>The difficulty soon vanishes, if once we clearly understand
+    that all these thousands of feet of rock were built up slowly,
+    layer after layer, when portions of the land lay deep under the
+    sea. Thus <i>each separate layer</i> of mud or sand or other
+    material became in its turn the <i>top layer</i>, and was for
+    the time the floor of the ocean, until further droppings of
+    material out of the waters made a fresh layer, covering up the
+    one below.</p>
+
+    <p>While each layer was thus in succession the top layer of the
+    building, and at the same time the floor <span class=
+    "pagenum"><a id="page19"></a>[pg 19]</span> of the ocean, animals lived
+       and died in the ocean, and their remains sank to the bottom,
+       resting upon the sediment floor. Thousands of such dead
+       remains disappeared, crumbling into fine dust and mingling
+       with the waters, but here and there one was caught captive
+       by the half-liquid mud, and was quickly covered and
+       preserved from decay. And still the building went on, and
+       still layer after layer was placed, till many fossils lay
+       deep down beneath the later-formed layers; and when at
+       length, by slow or quick upheaval of the ground, this
+       sea-bottom became a mountain, the little fossils were buried
+       within the body of that mountain. So wondrously the matter
+       appears to have come about.</p>
+    <hr>
+
+    <p>Another difficulty with respect to the stratified rocks has
+    to be thought of. All these layers or deposits of gravel, sand,
+    or earth, on the floor of the ocean, would naturally be
+    horizontal&mdash;that is, would lie flat, one upon another. In
+    places the ocean-floor might slant, or a crevice or valley or
+    ridge might break the smoothness of the deposit. But though the
+    layers might partake of the slant, though the valley might have
+    to be filled, though the ridge might have to be surmounted,
+    still the general tendency of the waves would be to level the
+    dropping deposits into flat layers.</p>
+
+    <p>Then how is it that when we examine the strata of rocks in
+    our neighborhood, wherever that neighborhood may be, we do not
+    find them so arranged? Here, it is true, the lines for a space
+    are nearly horizontal, but there, a little way farther on, they
+    are perpendicular; here they are bent, and there curved; here
+    they are slanting, and there crushed and
+          broken.</p><span class="pagenum"><a id="page20"></a>[pg 20]</span>
+
+    <p>This only bears out what has been already said about the
+    Book of Geology. It <i>has</i> been bent and disturbed, crushed
+    and broken.</p>
+
+    <p>Great powers have been at work in this crust of our earth.
+    Continents have been raised, mountains have been upheaved, vast
+    masses of rock have been scattered into fragments. Here or
+    there we may find the layers arranged as they were first laid
+    down; but far more often we discover signs of later
+    disturbance, either slow or sudden, varying from a mere quiet
+    tilting to a violent overturn.</p>
+
+    <div class="figleft"
+         style="width:400px;">
+        <a href="images/020.png"><img width="400"
+             src="images/020.png"
+             alt=
+           "EXAMPLE OF DISTURBANCE OF THE EARTH'S LAYERS."></a><br>
+        EXAMPLE OF DISTURBANCE OF THE EARTH'S LAYERS.
+    </div>
+
+    <p>So the Book of Geology is a torn and disorganized volume,
+    not easy to read.</p>
+
+    <p>Yet, on the other hand, these very changes which have taken
+    place are a help to the geologist.</p>
+
+    <p>It may seem at first sight as if we should have an easier
+    task, if the strata were all left lying just as they were first
+    formed, in smooth level layers, one above another. But if it
+    were so, we could know very little about the lower layers.</p>
+
+    <p>We might indeed feel sure, as we do now, that the lowest
+    layers were the oldest and the top layers the newest, and that
+    any fossils found in the lower layers must belong to an age
+    farther back than any fossils found in the upper
+    layers.</p><span class="pagenum"><a id="page21"></a>[pg 21]</span>
+
+    <p>So much would be clear. And we might dig also and burrow a
+    little way down, through a few different kinds of rock, where
+    they were not too thick. But that would be all. There our
+    powers would cease.</p>
+
+    <p>Now how different. Through the heavings and tiltings of the
+    earth's crust, the lower layers are often pushed quite up to
+    the surface, so that we are able to examine them and their
+    fossils without the least difficulty, and very often without
+    digging underground at all.</p>
+
+    <p>You must not suppose that the real order of the rocks is
+    changed by these movements, for generally speaking it is not.
+    The lower kinds are rarely if ever found placed <i>over</i> the
+    upper kinds; only the ends of them are seen peeping out above
+    ground.</p>
+
+    <p>It is as if you had a pile of copy-books lying flat one upon
+    another, and were to put your finger under the lowest and push
+    it up. All those above would be pushed up also, and perhaps
+    they would slip a little way down, so that you would have a row
+    of <i>edges</i> showing side by side, at very much the same
+    height. The arrangement of the copy-books would not be changed,
+    for the lowest would still be the lowest in actual position;
+    but a general tilting or upheaval would have taken place.</p>
+
+    <p>Just such a tilting or upheaval has taken place again and
+    again with the rocks forming our earth-crust. The edges of the
+    lower rocks often show side by side with those of higher
+    layers.</p>
+
+    <p>But geologists know them apart. They are able to tell
+    confidently whether such and such a rock, peeping out at the
+    earth's surface, belongs really to a lower or
+          <span class="pagenum"><a id="page22"></a>[pg 22]</span> a higher kind. For there is a
+       certain sort of order followed in the arrangement of
+       rock-layers all over the earth, and it is well known that
+       some rocks are never found below some other rocks, that
+       certain particular kinds are never placed above certain
+       other kinds. Thus it follows that the fossils found in one
+       description of rock, must be the fossils of animals which
+       lived and died before the animals whose fossil remains are
+       found in another neighboring rock, just because this last
+       rock-layer was built upon the ocean-floor above and
+       therefore later than the other.</p>
+
+    <p>All this is part of the foreign language of
+    geology&mdash;part of the piecing and arranging of the torn
+    volume. Many mistakes are made; many blunders are possible; but
+    the mistakes and blunders are being gradually corrected, and
+    certain rules by which to read and understand are becoming more
+    and more clear.</p>
+
+    <p>It has been already said that unstratified rocks are those
+    which have been at some period, whether lately or very long
+    ago, in a liquid state from intense heat, and which have since
+    cooled, either quickly or slowly, crystallizing as they
+    cooled.</p>
+
+    <p>Unstratified Rocks may be divided into two distinct
+    classes.</p>
+
+    <div class="figleft"
+         style="width:400PX;">
+        <a href="images/022.png"><img width="400"
+             src="images/022.png"
+             alt="SECTION OF A LAVA BOMB."></a><br>
+        SECTION OF A LAVA BOMB.
+    </div>
+
+    <p>First.&mdash;Volcanic Rocks, such as lava. These have been
+    quickly cooled at the surface of the earth, or not far below
+    it.</p><span class="pagenum"><a id="page23"></a>[pg 23]</span>
+
+    <p>Secondly.&mdash;Plutonic Rocks, such as granite. These have
+    been slowly cooled deep down in the earth under heavy
+    pressure.</p>
+
+    <p>There is also a class of rocks, called metamorphic rocks,
+    including some kinds of marble. These are, strictly speaking,
+    crystalline rocks, and yet they are arranged in something like
+    layers. The word "metamorphic" simply means "transformed." They
+    are believed to have been once stratified rocks, perhaps
+    containing often the remains of animals; but intense heat has
+    later transformed them into crystalline rocks, and the animal
+    remains have almost or quite vanished.</p>
+
+    <div class="figright"
+         style="width:400PX;">
+        <a href="images/023.png"><img width="400"
+             src="images/023.png"
+             alt="LAVA-STREAM ON VESUVIUS."></a><br>
+        LAVA-STREAM ON VESUVIUS.
+    </div>
+
+    <p>Just as the different kinds of Stratified Rocks are often
+    called Aqueous Rocks, or rocks formed by the action of
+    water&mdash;so these different kinds of Unstratified Rocks are
+    often called Igneous Rocks, or rocks formed by the action of
+    fire&mdash;the name being taken from the Latin word for fire.
+    The Metamorphic Rocks are sometimes described as
+    "Aqueo-igneous," since both water and fire helped in the
+    forming of them.</p>
+
+    <p>It was at one time believed, as a matter of certainty, that
+    granite and such rocks belonged to a period much farther back
+    than the periods of the stratified rocks. <span class=
+    "pagenum"><a id="page24"></a>[pg 24]</span> That is to say, it was
+       supposed that fire-action had come first and water-action
+       second; that the fire-made rocks were all formed in very
+       early ages, and that only water-made rocks still continued
+       to be formed. So the name of Primary Rocks, or First Rocks,
+       was given to the granites and other such rocks, and the name
+       of Secondary Rocks to all water-built rocks; while those of
+       the third class were called Transition Rocks, because they
+       seemed to be a kind of link or stepping-stone in the change
+       from the First to the Second Rocks.</p>
+
+    <p>The chief reason for the general belief that fire-built
+    rocks were older than water-built ones was, that the former are
+    as a rule found to lie <i>lower</i> than the latter. They form,
+    as it were, the basement of the building, while the top-stories
+    are made of water-built rocks.</p>
+
+    <p>Many still believe that there is much truth in the thought.
+    It is most probable, so far as we are able to judge, that the
+    <i>first-formed</i> crust of rocks all over the earth was of
+    cooled and crystallized material. As these rocks were crumbled
+    and wasted by the ocean, materials would have been supplied for
+    the building-up of rocks, layer upon layer.</p>
+
+    <p>But this is conjecture. We cannot know with any certainty
+    the course of events so far back in the past. And geologists
+    are now able to state with tolerable confidence that, however
+    old many of the granites may be, yet a large amount of the
+    fire-built rocks are no older than the water-built rocks which
+    lie over them.</p>
+
+    <p>So by many geologists the names of Primary, Transition, and
+    Secondary Formations are pretty well given up. It has been
+    proposed to give instead to the <span class=
+       "pagenum"><a id="page25"></a>[pg 25]</span> crystallized rocks of all
+       kinds the name of Underlying Rocks (Hypogene Rocks).</p>
+
+    <p>But if they really do lie under, how can they possibly be of
+    the same age? One would scarcely venture to suppose, in looking
+    at a building, that the cellars had not been finished before
+    the upper floors.</p>
+
+    <p>True. In the first instance doubtless the cellars were first
+    made, then the ground-floor, then the upper stories.</p>
+
+    <p>When, however, the house was so built, alterations and
+    improvements might be very widely carried on above and below.
+    While one set of workmen were engaged in remodelling the roof,
+    another set of workmen might be engaged in remodelling the
+    kitchens and first floor, pulling down, propping up, and
+    actually rebuilding parts of the lower walls.</p>
+
+    <p>This is precisely what the two great fellow-workmen, Fire
+    and Water, are ever doing in the crust of our earth. And if it
+    be objected that such alterations too widely undertaken might
+    result in slips, cracks, and slidings, of ceilings and walls in
+    the upper stories, I can only say that such catastrophes
+    <i>have</i> been the result of underground alterations in that
+    great building, the earth's crust....</p>
+
+    <p>We see therefore clearly that, although the earliest
+    fire-made rocks may very likely date farther back than the
+    earliest water-made rocks, yet the making of the two kinds has
+    gone on side by side, one below and the other above ground,
+    through all ages up to the present moment.</p>
+
+    <p>And just as in the present day water continues its
+    <span class="pagenum"><a id="page26"></a>[pg 26]</span> busy work above ground of
+       pulling down and building up, so also fire continues its
+       busy work underground of melting rocks which afterwards cool
+       into new forms, and also of shattering and upheaving parts
+       of the earth-crust.</p>
+
+    <p>For there can be no doubt that fiery heat does exist as a
+    mighty power within our earth, though to what extent we are not
+    able to say.</p>
+
+    <p>These two fellow-workers in nature have different modes of
+    working. One we can see on all sides, quietly progressing,
+    demolishing land patiently bit by bit, building up land
+    steadily grain by grain. The other, though more commonly hidden
+    from sight, is fierce and tumultuous in character, and shows
+    his power in occasional terrific outbursts.</p>
+
+    <p>We can scarcely realize what the power is of the imprisoned
+    fiery forces underground, though even we are not without some
+    witness of their existence. From time to time even our firm
+    land has been felt to tremble with a thrill from some far-off
+    shock; and even in our country is seen the marvel of scalding
+    water pouring unceasingly from deep underground....</p>
+
+    <p>Think of the tremendous eruptions of Vesuvius, of Etna, of
+    Hecla, of Mauna Loa. Think of whole towns crushed and buried,
+    with their thousands of living inhabitants. Think of rivers of
+    glowing lava streaming up from regions below ground, and
+    pouring along the surface for a distance of forty, fifty, and
+    even sixty miles, as in Iceland and Hawaii. Think of red-hot
+    cinders flung from a volcano-crater to a height of ten thousand
+    feet. Think of lakes of liquid fire in other craters, five
+    hundred to a thousand feet across, huge <span class=
+    "pagenum"><a id="page27"></a>[pg 27]</span> cauldrons of boiling rock.
+       Think of showers of ashes from the furnace below of yet
+       another, borne so high aloft as to be carried seven hundred
+       miles before they sank to earth again. Think of millions of
+       red-hot stones flung out in one eruption of Vesuvius. Think
+       of a mass of rock, one hundred cubic yards in size, hurled
+       to a distance of eight miles or more out of the crater of
+       Cotopaxi.</p>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/027.png"><img width="600"
+             src="images/027.png"
+             alt="HOT WELLS."></a><br>
+        HOT WELLS.
+    </div>
+
+    <p>Think also of earthquake-shocks felt through twelve hundred
+    miles of country. Think of fierce tremblings and heavings
+    lasting in constant succession through days and weeks of
+    terror. Think of hundreds of miles of land raised several feet
+    in one great upheaval. Think of the earth opening in scores of
+    wide-lipped cracks, to swallow men and beasts. Think of hot
+    mud, boiling water, scalding stream, liquid rock, bursting
+    <span class="pagenum"><a id="page28"></a>[pg 28]</span> from such cracks, or pouring
+       from rents in a mountain-side.</p>
+
+    <p>Truly these are signs of a state of things in or below the
+    solid crust on which we live, that may make us doubt the
+    absolute security of "Mother Earth."</p>
+
+    <p>Different explanations have been put forward to explain this
+    seemingly fiery state of things underground.</p>
+
+    <p>Until lately the belief was widely held that our earth was
+    one huge globe of liquid fire, with only a slender cooled crust
+    covering her, a few miles in thickness.</p>
+
+    <p>This view was supported by the fact that heat is found to
+    increase as men descend into the earth. Measurements of such
+    heat-increase have been taken, both in mines and in borings for
+    wells. The usual rate is about one degree more of heat, of our
+    common thermometer, for every fifty or sixty feet of descent.
+    If this were steadily continued, water would boil at a depth of
+    eight thousand feet below the surface; iron would melt at a
+    depth of twenty-eight miles; while at a depth of forty or fifty
+    miles no known substance upon earth could remain solid.</p>
+
+    <p>The force of this proof is, however, weakened by the fact
+    that the rate at which the heat increases differs very much in
+    different places. Also it is now generally supposed that such a
+    tremendous furnace of heat&mdash;a furnace nearly eight
+    thousand miles in diameter&mdash;could not fail to break up and
+    melt so slight a covering shell.</p>
+
+    <p>Many believe, therefore, not that the whole interior of
+    <span class="pagenum"><a id="page29"></a>[pg 29]</span> the earth is liquid with
+       heat, but that enormous fire-seas or lakes of melted rock
+       exist here and there, under or in the earth-crust. From
+       these lakes the volcanoes would be fed, and they would be
+       the cause of earthquakes and land-upheavals or
+       land-sinkings. There are strong reasons for supposing that
+       the earth was once a fiery liquid body, and that she has
+       slowly cooled through long ages. Some hold that her centre
+       probably grew solid first from tremendous pressure; that her
+       crust afterwards became gradually cold; and that between the
+       solid crust and the solid inside or "nucleus," a sea of
+       melted rock long existed, the remains of which are still to
+       be found in these tremendous fiery reservoirs.</p>
+
+    <p>The idea accords well with the fact that large numbers of
+    extinct or dead volcanoes are scattered through many parts of
+    the earth. If the above explanation be the right one, doubtless
+    the fire-seas in the crust extended once upon a time beneath
+    such volcanoes, but have since died out or smouldered low in
+    those parts.</p>
+
+    <p>A somewhat curious calculation has been made, to illustrate
+    the different modes of working of these two mighty
+    powers&mdash;Fire and Water.</p>
+
+    <p>The amount of land swept away each year in mud, and borne to
+    the ocean by the River Ganges, was roughly reckoned, and also
+    the amount of land believed to have been upheaved several feet
+    in the great Chilian earthquake.</p>
+
+    <p>It was found that the river, steadily working month by
+    month, would require some four hundred years to carry to the
+    sea the same weight of material, which in <span class=
+    "pagenum"><a id="page30"></a>[pg 30]</span> one tremendous effort was
+       upheaved by the fiery underground forces.</p>
+
+    <p>Yet we must not carry this distinction too far. Fire does
+    not always work suddenly, or water slowly; witness the slow
+    rising and sinking of land in parts of the earth, continuing
+    through centuries; and witness also the effects of great floods
+    and storms.</p>
+
+    <p>The crust of the earth is made of rock. But what is rock
+    made of?</p>
+
+    <p>Certain leading divisions of rocks have been already
+    considered:</p>
+
+    <p>The Water-made Rocks;</p>
+
+    <p>The Fire-made Rocks, both Plutonic and Volcanic;</p>
+
+    <p>The Water-and-Fire-made Rocks.</p>
+
+    <p>The first of these&mdash;Water-made Rocks&mdash;may be
+    subdivided into three classes. These are,&mdash;</p>
+
+    <p>I. <i>Flint Rocks</i>; II. <i>Clay Rocks</i>; III. <i>Lime
+    Rocks</i>.</p>
+
+    <p>This is not a book in which it would be wise to go closely
+    into the mineral nature of rocks. Two or three leading thoughts
+    may, however, be given.</p>
+
+    <p>Does it not seem strange that the hard and solid rocks
+    should be in great measure formed of the same substances which
+    form the thin invisible air floating around us?</p>
+
+    <p>Yet so it is. There is a certain gas called Oxygen Gas.
+    Without that gas you could not live many minutes. Banish it
+    from the room in which you are sitting, and in a few minutes
+    you will die.</p>
+
+    <p>This gas makes up nearly one-quarter by weight of the
+    atmosphere round the whole earth.</p><span class=
+    "pagenum"><a id="page31"></a>[pg 31]</span>
+
+    <p>The same gas plays an important part in the ocean; for more
+    than three-quarters of water is <i>oxygen</i>.</p>
+
+    <p>It plays also an important part in rocks; for about half the
+    material of the entire earth's crust is oxygen.</p>
+
+    <p>Another chief material in rocks is <i>silicon</i>. This
+    makes up one-quarter of the crust, leaving only one-quarter to
+    be accounted for. Silicon mixed with oxygen makes silica or
+    quartz. There are few rocks which have not a large amount of
+    quartz in them. Common flint, sandstones, and the sand of our
+    shores, are made of quartz, and therefore belong to the first
+    class of Silicious or Flint Rocks. Granites and lavas are about
+    one-half quartz. The beautiful stones, amethyst, agate,
+    chalcedony, and jasper, are all different kinds of quartz.</p>
+
+    <p>Another chief material in rocks is a white metal called
+    <i>aluminium</i>. United to oxygen it becomes alumina, the
+    chief substance in clay. Rocks of this kind&mdash;such as
+    clays, and also the lovely blue gem, sapphire&mdash;are called
+    Argillaceous Rocks, from the Latin word for clay, and belong to
+    the second class. Such rocks keep fossils well.</p>
+
+    <p>Another is <i>calcium</i>. United to oxygen and carbonic
+    acid, it makes carbonate of lime, the chief substance in
+    limestone; so all limestones belong to the third class of
+    Calcareous or Lime Rocks.</p>
+
+    <p>Other important materials may be mentioned, such as
+    <i>magnesium, potassium, sodium, iron, carbon, sulphur,
+    hydrogen, chlorine, nitrogen</i>. These, with many more, not so
+    common, make up the remaining quarter of the earth-crust.</p>
+
+    <p>Carbon plays as important a part in animal and vegetable
+    life as silicon in rocks. Carbon is most <span class=
+    "pagenum"><a id="page32"></a>[pg 32]</span> commonly seen in three
+       distinct forms&mdash;as charcoal, as black-lead, and as the
+       pure brilliant diamond. Carbon united, in a particular
+       proportion, to oxygen, forms carbonic acid; and carbonic
+       acid united, in a particular proportion, to lime, forms
+       limestone.</p>
+
+    <p><i>Hydrogen</i> united to oxygen forms water. Each of these
+    two gases is invisible alone, but when they meet and mingle
+    they form a liquid.</p>
+
+    <p><i>Nitrogen</i> united to oxygen and to a small quantity of
+    carbonic acid gas forms our atmosphere.</p>
+
+    <p>Rocks of pure flint, pure clay, or pure lime, are rarely or
+    never met with. Most rocks are made up of several different
+    substances melted together.</p>
+    <hr>
+
+    <p>In the fire-built rocks no remains of animals are found,
+    though in water-built rocks they abound. Water-built rocks are
+    sometimes divided into two classes&mdash;those which only
+    contain occasional animal remains, and those which are more or
+    less built up of the skeletons of animals.</p>
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/032.png"><img width="250"
+             src="images/032.png"
+             alt=
+           "AMIBA PRINCEPS, ONE OF THE MANY ORDERS OF THE RHIZOPODA CLASS, MAGNIFIED ONE HUNDRED TIMES."></a><br>
+
+        <p>AMIBA PRINCEPS, ONE OF THE MANY ORDERS OF THE RHIZOPODA
+        CLASS, MAGNIFIED ONE HUNDRED TIMES.</p>
+    </div>
+
+    <p>There are some exceedingly tiny creatures inhabiting the
+    ocean, called Rhizopods. They live in minute shells, the
+    largest of which may be almost the size of a grain of wheat,
+    but by far the greater number are invisible as shells without a
+    microscope, and merely show as fine dust. The
+          <span class="pagenum"><a id="page33"></a>[pg 33]</span> rhizopods are of different
+       shapes, sometimes round, sometimes spiral, sometimes having
+       only one cell, sometimes having several cells. In the latter
+       case a separate animal lives in each cell. The animal is of
+       the very simplest as well as the smallest kind. He has not
+       even a mouth or a stomach but can take in food at any part
+       of his body.</p><br>
+
+    <div class="figright"
+         style="width:300px;">
+        <a href="images/033.png"><img width="300"
+             src="images/033.png"
+             alt="RHIZOPODS (MAGNIFIED)."></a><br>
+        RHIZOPODS (MAGNIFIED).
+    </div>
+
+    <p>These rhizopods live in the oceans in enormous numbers. Tens
+    of millions are ever coming into existence, living out their
+    tiny lives, dying, and sinking to the bottom.</p>
+
+    <p>There upon the ocean-floor gather their remains, a heaped-up
+    multitude of minute skeletons or shells, layer forming over
+    layer.</p>
+
+    <p>It was long suspected that the white chalk cliffs of England
+    were built up in some such manner as this through past ages.
+    And now at length proof has been found, in the shape of mud
+    dredged up from the ocean-bottom&mdash;mud entirely composed of
+    countless multitudes of these little shells, dropping there by
+    myriads, and becoming slowly joined together in one mass.</p>
+
+    <p>Just so, it is believed, were the white chalk cliffs
+    built&mdash;gradually prepared on the ocean-floor, and then
+    slowly or suddenly upheaved, so as to become a part of the dry
+    land.</p>
+
+    <p>Think what the enormous numbers must have been of tiny
+    living creatures, out of whose shells the wide
+          <span class="pagenum"><a id="page34"></a>[pg 34]</span> reaches of white chalk cliffs
+       have been made. Chalk cliffs and chalk layers extend from
+       Ireland, through England and France, as far as to the
+       Crimea. In the south of Russia they are said to be six
+       hundred feet thick. Yet one cubic inch of chalk is
+       calculated to hold the remains of more than one million
+       rhizopods. How many countless millions upon millions must
+       have gone to the whole structure! How long must the work of
+       building up have lasted!</p>
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/034-1.png"><img width="250"
+             src="images/034-1.png"
+             alt="THREE POLYPS OF CORAL."></a><br>
+        THREE POLYPS OF CORAL.
+    </div>
+
+    <p>These little shells do not always drop softly and evenly to
+    the ocean-floor, to become quietly part of a mass of shells.
+    Sometimes, where the ocean is shallow enough for the waves to
+    have power below, or where land currents can reach, they are
+    washed about, and thrown one against another, and ground into
+    fine powder; and the fine powder becomes in time, through
+    different causes, solid rock.</p>
+
+    <div class="figright"
+         style="width:250px;">
+        <a href="images/034-2.png"><img width="250"
+             src="images/034-2.png"
+             alt="CORAL POLYP."></a><br>
+        CORAL POLYP.
+    </div>
+
+    <p>Limestone is made in another way also. In the warm waters of
+    the South Pacific Ocean there are many islands, large and
+    small, which have <span class="pagenum"><a id="page35"></a>[pg 35]</span> been formed in a wonderful
+       manner by tiny living workers. The workers are soft
+       jelly-like creatures, called polyps, who labor together in
+       building up great walls and masses of coral.</p>
+
+    <div class="figcenter"
+         style="width:600px">
+        <a href="images/035-1.png"><img width="600"
+             src="images/035-1.png"
+             alt="CORAL ISLAND."></a><br>
+        CORAL ISLAND.
+    </div>
+
+    <div class="figright"
+         style="width:400px;">
+        <a href="images/035-2.png"><img width="400"
+             src="images/035-2.png"
+             alt="YOUNG CORAL POLYP ATTACHED TO A ROCK"></a><br>
+        YOUNG CORAL POLYP ATTACHED TO A ROCK AND EXPANDED.
+    </div>
+
+    <p>They never carry on their work above the surface of the
+    water, for in the air they would die. But the waves break the
+    coral, and heap it up above high-water mark, and carry earth
+    and seeds to drop there till at length a small low-lying island
+    is formed.</p>
+
+    <p>The waves not only heap up broken coral, but they grind the
+    coral into fine powder, and from this powder limestone rock is
+    made, just as it is from the powdered <span class=
+    "pagenum"><a id="page36"></a>[pg 36]</span> shells of rhizopods. The
+       material used by the polyps in building the coral is chiefly
+       lime, which they have the power of gathering out of the
+       water, and the fine coral-powder, sinking to the bottom,
+       makes large quantities of hard limestone. Soft chalk is
+       rarely, if ever, found near the coral islands.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/036.png"><img width="300"
+             src="images/036.png"
+             alt=
+           "WHITE CORAL. 2. PORTION OF A BRANCH (MAGNIFIED)."></a><br>
+        WHITE CORAL. 2. PORTION OF A BRANCH (MAGNIFIED).
+    </div>
+
+    <p>Limestones are formed in the same manner from the grinding
+    up of other sea-shells and fossils, various in kind; the powder
+    becoming gradually united into solid rock.</p>
+
+    <p>There is yet another way in which limestone is made, quite
+    different from all these. Sometimes streams of water have a
+    large quantity of lime in them; and these as they flow will
+    drop layers of lime which harden into rock. Or a lime-laden
+    spring, making its way through the roof of an underground
+    cavern, will leave all kinds of fantastic arrangements of
+    limestone wherever its waters can trickle and drip. Such a
+    cavern is called a "stalactite cave."</p>
+    <hr>
+
+    <p>So there are different kinds of fossil rock-making. There
+    may be rocks made of other materials, with fossil simply buried
+    in them. There may be rocks <span class="pagenum"><a name=
+    "page37"
+       id="page37"></a>[pg 37]</span> made entirely of fossils,
+       which have gathered in masses as they sank to the
+       sea-bottom, and have there become simply and lightly joined
+       together. There may be rocks made of the ground-up powder of
+       fossils, pressed into a solid substance or united by some
+       other substance.</p>
+
+    <p>Rocks are also often formed of whole fossils, or stones, or
+    shells, bound into one by some natural soft sticky cement,
+    which has gathered round them and afterwards grown hard, like
+    the cement which holds together the stones in a wall.</p>
+
+    <p>The tiny rhizopods (meaning root foot) which have so large a
+    share in chalk and limestone making, are among the smallest and
+    simplest known kinds of animal life.</p>
+
+    <p>There are also some very minute forms of vegetable life,
+    which exist in equally vast numbers, called Diatoms. For a long
+    while they were believed to be living animals, like the
+    rhizopods. Scientific men are now, however, pretty well agreed
+    that they really are only vegetables or plants.</p>
+
+    <p>The diatoms have each one a tiny shell or shield, not made
+    of lime like the rhizopod-shells, but of flint. Some think that
+    common flint may be formed of these tiny shells.</p>
+
+    <p>Again, there is a kind of rock called Mountain Meal, which
+    is entirely made up of the remains of diatoms. Examined under
+    the microscope, thousands of minute flint shields of various
+    shapes are seen. This rock, or earth, is very abundant in many
+    places, and is sometimes used as a polishing powder. In Bohemia
+    there is a layer of it no less than fourteen feet thick. Yet so
+    minute are the shells of which it is composed, that one square
+    inch of rock is said to contain about four <span class=
+    "pagenum"><a id="page38"></a>[pg 38]</span> thousand millions of them.
+       Each one of these millions is a separate distinct
+       fossil....</p>
+    <hr>
+
+    <div class="figleft"
+         style="width:250px">
+        <a href="images/038.png"><img width="250"
+             src="images/038.png"
+             alt=
+           "SUCCESSION OF BURIED COAL-GROWTHSAND ERECT TREE-STUMPS. SYDNEY, CAPE BRETON."></a>
+
+        <p>SUCCESSION OF BURIED COAL-GROWTHS AND ERECT TREE-STUMPS.
+        SYDNEY, CAPE BRETON.</p>
+
+        <p><i>a.</i> Sandstone, <i>b.</i> Shales, <i>c.</i>
+        Coal-seams, <i>d.</i> Bed containing Roots and Stumps <i>in
+        situ</i>.</p>
+    </div>
+
+    <p>If you examine carefully a piece of coal, you will find,
+    more or less clearly, markings like those which are seen in a
+    piece of wood. Sometimes they are very distinct indeed. Coal
+    abounds in impressions of leaves, ferns, and stems, and fossil
+    remains of plants and tree-trunks are found in numbers in
+    coal-seams.</p>
+
+    <p>Coal is a vegetable substance. The wide coal-fields of
+    Britain and other lands are the <i>fossil</i> remains of vast
+    forests.</p>
+
+    <p>Long ages ago, as it seems, broad and luxuriant forests
+    flourished over the earth. In many parts generation after
+    generation of trees lived and died and decayed, leaving no
+    trace of their existence, beyond a little layer of black mould,
+    soon to be carried away by wind and water. Coal could only be
+    formed where there were bogs and quagmires.</p>
+
+    <p>But in bogs and <span class="pagenum"><a id="page39"></a>[pg 39]</span> quagmires, and in shallow
+       lakes of low-lying lands, there were great gatherings of
+       slowly-decaying vegetable remains, trees, plants, and ferns
+       all mingling together. Then after a while the low lands
+       would sink and the ocean pouring in would cover them with
+       layers of protecting sand or mud; and sometimes the land
+       would rise again, and fresh forests would spring into life,
+       only to be in their turn overwhelmed anew, and covered by
+       fresh sandy or earthy deposits.</p>
+
+    <p>These buried forests lay through the ages following, slowly
+    hardening into the black and shining coal, so useful now to
+    man.</p>
+
+    <p>The coal is found thus in thin or thick seams, with other
+    rock-layers between, telling each its history of centuries long
+    past. In one place no less than sixteen such beds of coal are
+    found, one below another, each divided from the next above and
+    the next underneath by beds of clay or sand or shale. The
+    forests could not have grown in the sea, and the earth-layers
+    could not have been formed on land, therefore many land-risings
+    and sinkings must have taken place. Each bed probably tells the
+    tale of a succession of forests....</p>
+    <hr>
+
+    <p>Before going on to a sketch of the early ages of the Earth's
+    history&mdash;ages stretching back long long before the time of
+    Adam&mdash;it is needful to think yet for a little longer about
+    the manner in which that history is written, and the way in
+    which it has to be read.</p>
+
+    <p>For the record is one difficult to make out, and its style
+    of expression is often dark and mysterious. There is scarcely
+    any other volume in the great Book of Nature, which the student
+    is so likely to misread as this <span class=
+       "pagenum"><a id="page40"></a>[pg 40]</span> one. It is very needful,
+       therefore, to hold the conclusions of geologists with a
+       light grasp, guarding each with a "perhaps" or a "may be."
+       Many an imposing edifice has been built, in geology, upon a
+       rickety foundation which has speedily given way.</p>
+
+    <p>In all ages of the world's history up to the present day,
+    rock-making has taken place&mdash;fire-made rocks being
+    fashioned underground, and water-made rocks being fashioned
+    above ground though under water.</p>
+
+    <p>Also in all ages different kinds of rocks have been
+    fashioned side by side&mdash;limestone in one part of the
+    world, sandstone in another, chalk in another, clay in another,
+    and so on. There have, it is true, been ages when one kind
+    seems to have been the <i>chief</i> kind&mdash;an age of
+    limestone, or an age of chalk. But even then there were
+    doubtless more rock-buildings going on, though not to so great
+    an extent. On the other hand, there may have been ages during
+    which no limestone was made, or no chalk, or no clay. As a
+    general rule, however, the various sorts of rock-building have
+    probably gone on together. This was not so well understood by
+    early geologists as it is now.</p>
+
+    <p>The difficulty is often great of disentangling the different
+    strata, and saying which was earlier and which later
+    formed.</p>
+
+    <p>Still, by close and careful study of the rocks which compose
+    the earth's crust, a certain kind of order is found to exist,
+    more or less followed out in all parts of the world.
+    <i>When</i> each layer was formed in England or in America, the
+    geologist cannot possibly say. He can, however, assert, in
+    either place, that a certain mass of rock was formed before a
+    certain other mass <span class="pagenum"><a id="page41"></a>[pg 41]</span> in that same place, even
+       though the two may seem to lie side by side; for he knows
+       that they were so placed only by upheaval, and that once
+       upon a time the one lay beneath the other.</p>
+
+    <p>The geologist can go further. He can often declare that a
+    certain mass of rock in America and a certain mass of rock in
+    England, quite different in kind, were probably built up at
+    about the same time. How long ago that time was he would be
+    rash to attempt to say; but that the two belong to the same age
+    he has good reason for supposing.</p>
+
+    <p>We find rocks piled upon rocks in a certain order, so that
+    we may generally be pretty confident that the lower rocks were
+    first made, and the upper rocks the latest built. Further than
+    this, we find in all the said layers of water-built rocks signs
+    of past life.</p>
+
+    <p>As already stated, much of this life was ocean-life, though
+    not all.</p>
+
+    <p>Below the sea, as the rock-layers were being formed, bit by
+    bit, of earth dropping from the ocean to the ocean's floor,
+    sea-creatures lived out their lives and died by thousands, to
+    sink to that same floor. Millions passed away, dissolving and
+    leaving no trace behind; but thousands were
+    preserved&mdash;shells often, animals sometimes.</p>
+
+    <p>Nor was this all. For now and again some part of the
+    sea-bottom was upheaved, slowly or quickly, till it became dry
+    land. On this dry land animals lived again, and thousands of
+    them, too, died, and their bones crumbled into dust. But here
+    and there one was caught in bog or frost, and his remains were
+    preserved till, through lapse of ages, they turned to
+    stone.</p><span class="pagenum"><a id="page42"></a>[pg 42]</span>
+
+    <p>Yet again that land would sink, and over it fresh layers
+    were formed by the ocean-waters, with fresh remains of
+    sea-animals buried in with the layers of sand or lime; and once
+    more the sea-bottom would rise, perhaps then to continue as dry
+    land, until the day when man should discover and handle these
+    hidden remains.</p>
+
+    <p>Now note a remarkable fact as to these fossils, scattered
+    far and wide through the layers of stratified rock.</p>
+
+    <p>In the uppermost and latest built rocks the animals found
+    are the same, in great measure, as those which now exist upon
+    the earth.</p>
+
+    <p>Leaving the uppermost rocks, and examining those which lie a
+    little way below, we find a difference. Some are still the
+    same, and others, if not quite the same, are very much like
+    what we have now; but here and there a creature of a different
+    form appears.</p>
+
+    <p>Go deeper still, and the kinds of animals change further.
+    Fewer and fewer resemble those which now range the earth; more
+    and more belong to other species.</p>
+
+    <p>Descend through layer after layer till we come to rocks
+    built in earliest ages and not one fossil shall we find
+    precisely the same as one animal living now.</p>
+
+    <p>So not only are the rocks built in successive order, stratum
+    after stratum belonging to age after age in the past, but
+    fossil-remains also are found in successive order, kind after
+    kind belonging to past age after age.</p>
+
+    <p>Although in the first instance the succession of fossils was
+    understood by means of the succession of <span class=
+    "pagenum"><a id="page43"></a>[pg 43]</span> rock-layers, yet in the
+       second place the arrangement of rock-layers is made more
+       clear by the means of these very fossils.</p>
+
+    <p>A geologist, looking at the rocks in America, can say which
+    there were first-formed, which second-formed, which
+    third-formed. Also, looking at the rocks in England, he can say
+    which there were first-formed, second-formed, third-formed. He
+    would, however, find it very difficult, if not impossible, to
+    say which among any of the American rocks was formed at about
+    the same time as any particular one among the English rocks,
+    were it not for the help afforded him by these fossils.</p>
+
+    <p>Just as the regular succession of rock-strata has been
+    gradually learned, so the regular succession of different
+    fossils is becoming more and more understood. It is now known
+    that some kinds of fossils are always found in the oldest
+    rocks, and in them only; that some kinds are always found in
+    the newest rocks, and in them only; that some fossils are
+    rarely or never found lower than certain layers; that some
+    fossils are rarely or never found higher than certain other
+    layers.</p>
+
+    <p>So this fossil arrangement is growing into quite a history
+    of the past. And a geologist, looking at certain rocks, pushed
+    up from underground, in England and in America, can say: "These
+    are very different kinds of rocks, it is true, and it would be
+    impossible to say how long the building up of the one might
+    have taken place before or after the other. But I see that in
+    both these rocks there are exactly the same kinds of
+    fossil-remains, differing from those in the rocks above and
+    below. I conclude therefore that the two rocks belong to about
+    <span class="pagenum"><a id="page44"></a>[pg 44]</span> the same great age in the
+       world's past history, when the same animals were living upon
+       the earth."</p>
+
+    <p>Observing and reasoning thus, geologists have drawn up a
+    general plan or order of strata; and the whole of the vast
+    masses of water-built rocks throughout the world have been
+    arranged in a regular succession of classes, rising step by
+    step from earliest ages up to the present time.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/044.png"><img width="500"
+             src="images/044.png"
+             alt="Water built rocks."></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="page45"></a>[pg 45]</span>
+
+    <h2>AMERICA THE OLD WORLD</h2>
+
+    <h4 class="sc">(From Geological Sketches.)</h4>
+
+    <h3><span class="sc">By</span> L. AGASSIZ.</h3>
+    <hr class="short">
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/045.png"><img width="250"
+             src="images/045.png"
+             alt="Globe of Americas"></a>
+    </div>
+
+    <p>First-born among the Continents, though so much later in
+    culture and civilization than some of more recent birth,
+    America, so far as her physical history is concerned, has been
+    falsely denominated the <i>New World</i>. Hers was the first
+    dry land lifted out of the waters, hers the first shore washed
+    by the ocean that enveloped all the earth beside; and while
+    Europe was represented only by islands rising here and there
+    above the sea, America already stretched an unbroken line of
+    land from Nova Scotia to the Far West.</p>
+
+    <p>In the present state of our knowledge, our conclusions
+    respecting the beginning of the earth's history, the way in
+    which it took form and shape as a distinct, separate planet,
+    must, of course, be very vague and <span class=
+    "pagenum"><a id="page46"></a>[pg 46]</span> hypothetical. Yet the
+       progress of science is so rapidly reconstructing the past
+       that we may hope to solve even this problem; and to one who
+       looks upon man's appearance upon the earth as the crowning
+       work in a succession of creative acts, all of which have had
+       relation to his coming in the end, it will not seem strange
+       that he should at last be allowed to understand a history
+       which was but the introduction to his own existence. It is
+       my belief that not only the future, but the past also, is
+       the inheritance of man, and that we shall yet conquer our
+       lost birthright.</p>
+
+    <p>Even now our knowledge carries us far enough to warrant the
+    assertion that there was a time when our earth was in a state
+    of igneous fusion, when no ocean bathed it and no atmosphere
+    surrounded it, when no wind blew over it and no rain fell upon
+    it, but an intense heat held all its materials in solution. In
+    those days the rocks which are now the very bones and sinews of
+    our mother Earth&mdash;her granites, her porphyries, her
+    basalts, her syenites&mdash;were melted into a liquid mass. As
+    I am writing for the unscientific reader, who may not be
+    familiar with the facts through which these inferences have
+    been reached, I will answer here a question which, were we
+    talking together, he might naturally ask in a somewhat
+    sceptical tone. How do you know that this state of things ever
+    existed, and, supposing that the solid materials of which our
+    earth consists were ever in a liquid condition, what right have
+    you to infer that this condition was caused by the action of
+    heat upon them? I answer, Because it is acting upon them still;
+    because the earth we tread is but a thin crust floating on a
+    liquid sea of molten <span class="pagenum"><a id="page47"></a>[pg 47]</span> materials; because the
+       agencies that were at work then are at work now, and the
+       present is the logical sequence of the past. From artesian
+       wells, from mines, from geysers, from hot springs, a mass of
+       facts has been collected, proving incontestably the heated
+       condition of all substances at a certain depth below the
+       earth's surface; and if we need more positive evidence, we
+       have it in the fiery eruptions that even now bear fearful
+       testimony to the molten ocean seething within the globe and
+       forcing its way but from time to time. The modern progress
+       of Geology has led us by successive and perfectly connected
+       steps back to a time when what is now only an occasional and
+       rare phenomenon was the normal condition of our earth; when
+       the internal fires were enclosed by an envelope so thin that
+       it opposed but little resistance to their frequent outbreak,
+       and they constantly forced themselves through this crust,
+       pouring out melted materials that subsequently cooled and
+       consolidated on its surface. So constant were these
+       eruptions, and so slight was the resistance they
+       encountered, that some portions of the earlier rock-deposits
+       are perforated with numerous chimneys, narrow tunnels as it
+       were, bored by the liquid masses that poured <span class=
+       "pagenum"><a id="page48"></a>[pg 48]</span> out through them and greatly
+       modified their first condition.</p>
+
+    <div class="figright"
+         style="width:350px;">
+        <a href="images/047.png"><img width="350"
+             src="images/047.png"
+             alt="IDEAL SECTION OF A VOLCANO IN ACTION."></a><br>
+        IDEAL SECTION OF A VOLCANO IN ACTION.
+    </div>
+
+    <p>The question at once suggests itself, How was even this thin
+    crust formed? what should cause any solid envelope, however
+    slight and filmy when compared to the whole bulk of the globe,
+    to form upon the surface of such a liquid mass? At this point
+    of the investigation the geologist must appeal to the
+    astronomer; for in this vague and nebulous border-land, where
+    the very rocks lose their outlines and flow into each other,
+    not yet specialized into definite forms and
+    substances,&mdash;there the two sciences meet. Astronomy shows
+    us our planet thrown off from the central mass of which it once
+    formed a part, to move henceforth in an independent orbit of
+    its own. That orbit, it tells us, passed through celestial
+    spaces cold enough to chill this heated globe, and of course to
+    consolidate it externally. We know, from the action of similar
+    causes on a smaller scale and on comparatively insignificant
+    objects immediately about us, what must have been the effect of
+    this cooling process upon the heated mass of the globe. All
+    substances when heated occupy more space than they do when
+    cold. Water, which expands when freezing, is the only exception
+    to this rule. The first effect of cooling the surface of our
+    planet must have been to solidify it, and thus to form a film
+    or crust over it. That crust would shrink as the cooling
+    process went on; in consequence of the shrinking, wrinkles and
+    folds would arise upon it, and here and there, where the
+    tension was too great, cracks and fissures would be produced.
+    In proportion as the surface cooled, the masses within would be
+    affected by the change of <span class="pagenum"><a name=
+    "page49"
+       id="page49"></a>[pg 49]</span> temperature outside of them,
+       and would consolidate internally also, the crust gradually
+       thickening by this process.</p>
+
+    <div class="figcenter"
+         style="width:300px;">
+        <a href="images/069.jpg"><img width="300"
+             src="images/069sm.jpg"
+             alt="A VOLCANO."></a><br>
+        A VOLCANO.
+    </div>
+
+    <p>But there was another element without the globe, equally
+    powerful in building it up. Fire and water wrought together in
+    this work, if not always harmoniously, at least with equal
+    force and persistency. I have said that there was a time when
+    no atmosphere surrounded the earth; but one of the first
+    results of the cooling of its crust must have been the
+    formation of an atmosphere, with all the phenomena connected
+    with it,&mdash;the rising of vapors, their condensation into
+    clouds, the falling of rains, the gathering of waters upon its
+    surface. Water is a very active agent of destruction, but it
+    works over again the materials it pulls down or wears away, and
+    builds them up anew in other forms. As soon as an ocean washed
+    over the consolidated crust of the globe, it would begin to
+    abrade the surfaces upon which it moved, gradually loosening
+    and detaching materials, to deposit them again as sand or mud
+    or pebbles at its bottom in successive layers, one above
+    another. Thus, in analyzing the crust of the globe, we find at
+    once two kinds of rocks, the respective work of fire and water:
+    the first poured out from the furnaces within, and cooling, as
+    one may see any mass of metal cool that is poured out from a
+    smelting-furnace to-day, in solid crystalline masses, without
+    any division into separate layers or leaves; and the latter in
+    successive beds, one over another, the heavier materials below,
+    the lighter above, or sometimes in alternate layers, as special
+    causes may have determined successive deposits of lighter or
+    heavier materials at some given spot.</p><span class=
+    "pagenum"><a id="page50"></a>[pg 50]</span>
+
+    <p>There were many well-fought battles between geologists
+    before it was understood that these two elements had been
+    equally active in building up the crust of the earth. The
+    ground was hotly contested by the disciples of the two
+    geological schools, one of which held that the solid envelope
+    of the earth was exclusively due to the influence of fire,
+    while the other insisted that it had been accumulated wholly
+    under the agency of water. This difference of opinion grew up
+    very naturally; for the great leaders of the two schools lived
+    in different localities, and pursued their investigations over
+    regions where the geological phenomena were of an entirely
+    opposite character,&mdash;the one exhibiting the effect of
+    volcanic eruptions, the other that of stratified deposits. It
+    was the old story of the two knights on opposite sides of the
+    shield, one swearing that it was made of gold, the other that
+    it was made of silver; and almost killing each other before
+    they discovered that it was made of both. So prone are men to
+    hug their theories and shut their eyes to any antagonistic
+    facts, that it is related of Werner, the great leader of the
+    Aqueous school, that he was actually on his way to see a
+    geological locality of especial interest, but, being told that
+    it confirmed the views of his opponents, he turned round and
+    went home again, refusing to see what might force him to change
+    his opinions. If the rocks did not confirm his theory, so much
+    the worse for the rocks,&mdash;he would none of them. At last
+    it was found that the two great chemists, fire and water, had
+    worked together in the vast laboratory of the globe, and since
+    then scientific men have decided to work together also; and if
+    they still have a passage <span class="pagenum"><a name=
+    "page51"
+       id="page51"></a>[pg 51]</span> at arms occasionally over
+       some doubtful point, yet the results of their investigations
+       are ever drawing them nearer to each other,&mdash;since men
+       who study truth, when they reach their goal, must always
+       meet at last on common ground.</p>
+
+    <p>The rocks formed under the influence of heat are called, in
+    geological language, the Igneous, or, as some naturalists have
+    named them, the Plutonic rocks, alluding to their fiery origin,
+    while the others have been called Aqueous or Neptunic rocks, in
+    reference to their origin under the agency of water. A simpler
+    term, however, quite as distinctive, and more descriptive of
+    their structure, is that of the stratified and massive or
+    unstratified rocks. We shall see hereafter how the relative
+    position of these two classes of rocks and their action upon
+    each other enable us to determine the chronology of the earth,
+    to compare the age of her mountains, and, if we have no
+    standard by which to estimate the positive duration of her
+    continents, to say at least which was the first-born among
+    them, and how their characteristic features have been
+    successfully worked out. I am aware that many of these
+    inferences, drawn from what is called "the geological record,"
+    must seem to be the work of the imagination. In a certain sense
+    this is true,&mdash;for imagination, chastened by correct
+    observation, is our best guide in the study of Nature. We are
+    too apt to associate the exercise of this faculty with works of
+    fiction, while it is in fact the keenest detective of
+    truth.</p>
+
+    <div class="figleft"
+         style="width:350px;">
+        <a href="images/052.png"><img width="350"
+             src="images/052.png"
+             alt="DIKES."></a><br>
+        DIKES.
+    </div>
+
+    <p>Besides the stratified and massive rocks, there is still a
+    third set, produced by the contact of these two, and called, in
+    consequence of the changes thus brought <span class=
+    "pagenum"><a id="page52"></a>[pg 52]</span> about, the Metamorphic rocks.
+       The effect of heat upon clay is to bake it into slate;
+       limestone under the influence of heat becomes quick-lime,
+       or, if subjected afterwards to the action of water, it is
+       changed to mortar; sand under the same agency is changed to
+       a coarse kind of glass. Suppose, then, that a volcanic
+       eruption takes place in a region of the earth's surface
+       where successive layers of limestone, of clay, and of
+       sandstone, have been previously deposited by the action of
+       water. If such an eruption has force enough to break through
+       these beds, the hot, melted masses will pour out through the
+       rent, flow over its edges, and fill all the lesser cracks
+       and fissures produced by such a disturbance. What will be
+       the effect upon the stratified rocks? Wherever these liquid
+       masses, melted by a heat more intense than can be produced
+       by any artificial means, have flowed over them or cooled in
+       immediate contact with them, the clays will be changed to
+       slate, the limestone will have assumed a character more like
+       marble, while the sandstone will be vitrified. This is
+       exactly what has been found to be the case, wherever the
+       stratified rocks have been penetrated by the melted masses
+       from beneath. They have been themselves partially melted by
+       the contact, and when they have cooled again, their
+       stratification, though still perceptible, has been partly
+       obliterated, and their substance changed. Such effects
+       <span class="pagenum"><a id="page53"></a>[pg 53]</span> may often be traced in dikes,
+       which are only the cracks in rocks filled by materials
+       poured into them at some period of eruption when the melted
+       masses within the earth were thrown out and flowed like
+       water into any inequality or depression of the surface
+       around. The walls enclosing such a dike are often found to
+       be completely altered by contact with its burning contents,
+       and to have assumed a character quite different from the
+       rocks of which they make a part; while the mass itself which
+       fills the fissure shows by the character of its
+       crystallization that it has cooled more quickly on the
+       outside, where it meets the walls, than at the centre.</p>
+
+    <p>The first two great classes of rocks, the unstratified and
+    stratified rocks, represent different epochs in the world's
+    physical history: the former mark its revolutions, while the
+    latter chronicle its periods of rest. All mountains and
+    mountain-chains have been upheaved by great convulsions of the
+    globe, which rent asunder the surface of the earth, destroyed
+    the animals and plants living upon it at the time, and were
+    then succeeded by long intervals of repose, when all things
+    returned to their accustomed order, ocean and river deposited
+    fresh beds in uninterrupted succession, the accumulation of
+    materials went on as before, a new set of animals and plants
+    were introduced, and a time of building up and renewing
+    followed the time of destruction. These periods of revolution
+    are naturally more difficult to decipher than the periods of
+    rest; for they have so torn and shattered the beds they
+    uplifted, disturbing them from their natural relations to each
+    other, that it is not easy to reconstruct the parts and give
+    <span class="pagenum"><a id="page54"></a>[pg 54]</span> them coherence and
+       completeness again. But within the last half-century this
+       work has been accomplished in many parts of the world with
+       an amazing degree of accuracy, considering the disconnected
+       character of the phenomena to be studied; and I think I
+       shall be able to convince my readers that the modern results
+       of geological investigation are perfectly sound logical
+       inferences from well-established facts. In this, as in so
+       many other things, we are but "children of a larger growth."
+       The world is the geologist's great puzzle-box; he stands
+       before it like the child to whom the separate pieces of his
+       puzzle remain a mystery till he detects their relation and
+       sees where they fit, and then his fragments grow at once
+       into a connected picture beneath his hand....</p>
+
+    <p>When geologists first turned their attention to the physical
+    history of the earth, they saw at once certain great features
+    which they took to be the skeleton and basis of the whole
+    structure. They saw the great masses of granite forming the
+    mountains and mountain-chains, with the stratified rocks
+    resting against their slopes; and they assumed that granite was
+    the first primary agent, and that all stratified rocks must be
+    of a later formation. Although this involved a partial error,
+    as we shall see hereafter when we trace the upheavals of
+    granite even into comparatively modern periods, yet it held an
+    important geological truth also; for, though granite formations
+    are by no means limited to those early periods, they are
+    nevertheless very characteristic of them, and are indeed the
+    foundation-stones on which the physical history of the globe is
+    built.</p>
+
+    <p>Starting from this landmark, the earlier geologists
+    <span class="pagenum"><a id="page55"></a>[pg 55]</span> divided the world's history
+       into three periods. As the historian recognizes Ancient
+       History, the Middle Ages, and Modern History as distinct
+       phases in the growth of the human race, so they
+       distinguished between what they called the Primary period,
+       when, as they believed, no life stirred on the surface of
+       the earth; the Secondary or middle period, when animals and
+       plants were introduced, and the land began to assume
+       continental proportions; and the Tertiary period, or
+       comparatively modern geological times, when the physical
+       features of the earth as well as its inhabitants were
+       approaching more nearly to the present condition of things.
+       But as their investigations proceeded, they found that every
+       one of these great ages of the world's history was divided
+       into numerous lesser epochs, each of which had been
+       characterized by a peculiar set of animals and plants, and
+       had been closed by some great physical convulsion,
+       disturbing and displacing the materials accumulated during
+       such a period of rest.</p>
+
+    <p>The further study of these subordinate periods showed that
+    what had been called Primary formations, namely, the volcanic
+    or Plutonic rocks formerly believed to be confined to the first
+    geological ages, belonged to all the periods, successive
+    eruptions having taken place at all times, pouring up through
+    the accumulated deposits, penetrating and injecting their
+    cracks, fissures, and inequalities, as well as throwing out
+    large masses on the surface. Up to our own day there has never
+    been a period when such eruptions have not taken place, though
+    they have been constantly diminishing in frequency and extent.
+    In consequence of this discovery, that rocks of igneous
+    character were by no <span class="pagenum"><a id="page56"></a>[pg 56]</span> means exclusively
+       characteristic of the earliest times, they are now
+       classified together upon very different grounds from those
+       on which geologists first united them; though, as the name
+       <i>Primary</i> was long retained, we still find it applied
+       to them, even in geological works of quite recent date. This
+       defect of nomenclature is to be regretted, as likely to
+       mislead the student, because it seems to refer to time;
+       whereas it no longer signifies the age of the rocks, but
+       simply their character. The name Plutonic or Massive rocks
+       is, however, now almost universally substituted for that of
+       Primary.</p>
+
+    <p>A wide field of investigation still remains to be explored
+    by the chemist and the geologist together, in the mineralogical
+    character of the Plutonic rocks, which differs greatly in the
+    different periods. The earlier eruptions seem to have been
+    chiefly granitic, though this must not be understood in too
+    wide a sense, since there are granite formations even as late
+    as the Tertiary period; those of the middle periods were mostly
+    porphyries and basalts; while in the more recent ones, lavas
+    predominate. We have as yet no clew to the laws by which this
+    distribution of volcanic elements in the formation of the earth
+    is regulated; but there is found to be a difference in the
+    crystals of the Plutonic rocks belonging to different ages,
+    which, when fully understood may enable us to determine the age
+    of any Plutonic rock by its mode of crystallization; so that
+    the mineralogist will as readily tell you by its crystals
+    whether a bit of stone of igneous origin belongs to this or
+    that period of the world's history, as the palæontologist will
+    tell you by its fossils whether a piece of rock
+          <span class="pagenum"><a id="page57"></a>[pg 57]</span> of aqueous origin belongs to
+       the Silurian or Devonian or Carboniferous deposits.</p>
+
+    <p>Although subsequent investigations have multiplied so
+    extensively not only the number of geological periods, but also
+    the successive creations that have characterized them, yet the
+    first general division into three great eras was nevertheless
+    founded upon a broad and true generalization. In the first
+    stratified rocks in which any organic remains are found, the
+    highest animals are fishes, and the highest plants are
+    cryptogams; in the middle periods reptiles come in, accompanied
+    by fern and moss forests; in later times quadrupeds are
+    introduced, with a dicotyledonous vegetation. So closely does
+    the march of animal and vegetable life keep pace with the
+    material progress of the world, that we may well consider these
+    three divisions, included under the first general
+    classification of its physical history, as the three Ages of
+    Nature; the more important epochs which subdivide them may be
+    compared to so many great dynasties, while the lesser periods
+    are the separate reigns contained therein. Of such epochs there
+    are ten, well known to geologists; of the lesser periods about
+    sixty are already distinguished, while many more loom up from
+    the dim regions of the past, just discerned by the eye of
+    science, though their history is not yet unravelled.</p>
+
+    <p>Before proceeding further, I will enumerate the geological
+    epochs in their succession, confining myself, however, to such
+    as are perfectly well established, without alluding to those of
+    which the limits are less definitely determined, and which are
+    still subject to doubts and discussions among geologists. As I
+    do not propose to <span class="pagenum"><a id="page58"></a>[pg 58]</span> make here any treatise of
+       Geology, but simply to place before my readers some pictures
+       of the old world, with the animals and plants that have
+       inhabited it at various times, I shall avoid, as far as
+       possible, all debatable ground, and confine myself to those
+       parts of my subject which are best known, and can therefore
+       be more clearly presented.</p>
+
+    <div class="figleft"
+         style="width:250px">
+        <a href="images/058.png"><img width="250"
+             src="images/058.png"
+             alt="FOSSIL SCORPION.--SILURIAN PERIOD."></a><br>
+        FOSSIL SCORPION.&mdash;SILURIAN PERIOD.
+    </div>
+
+    <p>First, we have the Azoic period, <i>devoid of life</i>, as
+    its name signifies,&mdash;namely, the earliest stratified
+    deposits upon the heated film forming the first solid surface
+    of the earth, in which no trace of living thing has ever been
+    found. Next comes the Silurian period, when the crust of the
+    earth had thickened and cooled sufficiently to render the
+    existence of animals and plants upon it possible, and when the
+    atmospheric conditions necessary to their maintenance were
+    already established. Many of the names given to these periods
+    are by no means significant of their character, but are merely
+    the result of accident: as, for instance, that of Silurian,
+    given by Sir Roderick Murchison to this set of beds, because he
+    first studied them in that part of Wales occupied by the
+    ancient tribe of the Silures. The next period, the Devonian,
+    was for a similar reason <span class="pagenum"><a id="page59"></a>[pg 59]</span> named after the country of
+       Devonshire in England, where it was first investigated. Upon
+       this follows the Carboniferous period, with the immense
+       deposits of coal from which it derives its name. Then comes
+       the Permian period, named, again, from local circumstances,
+       the first investigation of its deposits having taken place
+       in the province of Permia in Russia. Next in succession we
+       have the Triassic period, so called from the trio of rocks,
+       the red sandstone, Muschel Kalk (shell-limestone), and
+       Keuper (clay), most frequently combined in its formations;
+       the Jurassic, so amply illustrated in the chain of the Jura,
+       where geologists first found the clew to its history; and
+       the Cretaceous period, to which the chalk cliffs of England
+       and all the extensive chalk deposits belong. Upon these
+       follow the so-called Tertiary formations, divided into three
+       periods, all of which have received most characteristic
+       names in this epoch of the world's history we see the first
+       approach to a condition of things resembling that now
+       prevailing, and Sir Charles Lyell has most fitly named
+       <span class="pagenum"><a id="page60"></a>[pg 60]</span> its three divisions, the
+       Eocene, Miocene, and Pliocene. The termination of the three
+       words is made from the Greek word <i>Kainos</i>, recent;
+       while <i>Eos</i> signifies dawn, <i>Meion</i> less, and
+       <i>Pleion</i> more. Thus Eocene indicates the dawn of recent
+       species, Pliocene their increase, while Miocene, the
+       intermediate term, means less recent. Above these deposits
+       comes what has been called in science the present
+       period,&mdash;<i>the modern times</i> of the
+       geologist,&mdash;that period to which man himself belongs,
+       and since the beginning of which, though its duration be
+       counted by hundreds of thousands of years, there has been no
+       alteration in the general configuration of the earth,
+       consequently no important modification of its climatic
+       conditions, and no change in the animals and plants
+       inhabiting it.</p>
+
+    <div class="figcenter"
+         style="width:250px">
+        <a href="images/059-1.png"><img width="250"
+             src="images/059-1.png"
+             alt="CRUSTACEA.--DEVONIAN PERIOD."></a><br>
+        CRUSTACEA.&mdash;DEVONIAN PERIOD.
+    </div>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/059-2.png"><img width="500"
+             src="images/059-2.png"
+             alt="FISH OF THE DEVONIAN PERIOD."></a><br>
+        FISH OF THE DEVONIAN PERIOD.
+    </div>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/060-1.png"><img width="500"
+             src="images/060-1.png"
+             alt="FISH OF THE CARBONIFEROUS PERIOD."></a><br>
+        FISH OF THE CARBONIFEROUS PERIOD.
+    </div>
+
+    <div class="figcenter"
+         style="width:300px;">
+        <a href="images/060-2.png"><img width="300"
+             src="images/060-2.png"
+             alt=
+           "FOSSIL VEGETATION OF CARBONIFEROUS PERIOD."></a><br>
+        FOSSIL VEGETATION OF CARBONIFEROUS PERIOD.
+    </div>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/060-3.png"><img width="300"
+             src="images/060-3.png"
+             alt="FISH OF THE PERMIAN PERIOD."></a><br>
+        FISH OF THE PERMIAN PERIOD.
+    </div>
+
+    <p>I have spoken of the first of these periods, the Azoic,
+    <span class="pagenum"><a id="page61"></a>[pg 61]</span> as having been absolutely
+       devoid of life, and I believe this statement to be strictly
+       true; but I ought to add that there is a difference of
+       opinion among geologists upon this point, many believing
+       that the first surface of our globe may have been inhabited
+       by living beings, but that all traces of their existence
+       have been obliterated by the eruptions of melted materials,
+       which not only altered the character of those earliest
+       stratified rocks, but destroyed all the organic remains
+       contained in them. It will be my object to show, not only
+       that the absence of the climatic and atmospheric conditions
+       essential to organic life, as we understand it, must have
+       rendered the previous existence of any living beings
+       impossible, but also that the completeness of the Animal
+       Kingdom in those deposits where we first find organic
+       remains, its intelligible and coherent connections with the
+       successive creations of all geological times and with the
+       animals now living, afford the strongest internal evidence
+       that we have indeed found in the lower Silurian formations,
+       immediately following the Azoic, the beginning of life upon
+       earth. When a story seems to us complete <span class=
+       "pagenum"><a id="page62"></a>[pg 62]</span> and consistent from the
+       beginning to the end, we shall not seek for a first chapter,
+       even though the copy in which we have read it be so torn and
+       defaced as to suggest the idea that some portion of it may
+       have been lost. The unity of the work, as a whole, is an
+       incontestable proof that we possess it in its original
+       integrity. The validity of this argument will be recognized,
+       perhaps, only by those naturalists to whom the Animal
+       Kingdom has begun to appear as a connected whole. For those
+       who do not see order in Nature it can have no value.</p>
+
+    <table>
+        <tr>
+            <td>
+                <div class="figleft"
+                     style="width:300px;">
+                    <a href="images/061-1.png"><img width="300"
+                         src="images/061-1.png"
+                         alt=
+                       "FOSSILS OF TRIASSIC VEGETATION."></a><br>
+                    FOSSILS OF TRIASSIC VEGETATION.
+                </div>
+            </td>
+
+            <td>
+                <div class="figright"
+                     style="width:300px;">
+                    <a href="images/061-2.png"><img width="300"
+                         src="images/061-2.png"
+                         alt=
+                       "BIRD OF THE JURASSIC PERIOD.(The Oldest Bird.)"></a><br>
+                    BIRD OF THE JURASSIC PERIOD.(The Oldest Bird.)
+                </div>
+            </td>
+        </tr>
+    </table><br>
+
+    <div class="figcenter"
+         style="width:300px;">
+        <a href="images/062-1.png"><img width="300"
+             src="images/062-1.png"
+             alt=
+           "SKELETON OF BIRD OF THE CRETACEOUS PERIOD."></a><br>
+        SKELETON OF BIRD OF THE CRETACEOUS PERIOD.
+    </div><br>
+
+    <div class="figleft"
+         style="width:350px;">
+        <a href="images/062-2.png"><img width="350"
+             src="images/062-2.png"
+             alt=
+           "SKELETON OF ANIMAL OF THE EOCENE PERIOD."></a><br>
+        SKELETON OF ANIMAL OF THE EOCENE PERIOD.
+    </div>
+
+    <p>For a table containing the geological periods in their
+    succession, I would refer to any modern text-book of Geology,
+    or to an article in the <i>Atlantic Monthly</i> for March,
+    1862, upon "Methods of Study in Natural History," where they
+    are given in connection with the order of introduction of
+    animals upon earth.</p>
+
+    <p>Were these sets of rocks found always in the regular
+    sequence in which I have enumerated them, their relative age
+    would be <span class="pagenum"><a id="page63"></a>[pg 63]</span> easily determined, for their
+       superposition would tell the whole story: the lowest would,
+       of course, be the oldest, and we might follow without
+       difficulty the ascending series, till we reached the
+       youngest and uppermost deposits. But their succession has
+       been broken up by frequent and violent alterations in the
+       configuration of the globe. Land and water have changed
+       their level,&mdash;islands have been transformed to
+       continents,&mdash;sea-bottoms have become dry land, and dry
+       land has sunk to form sea-bottoms,&mdash;Alps and Himalayas,
+       Pyrenees and Apennines, Alleghanies and Rocky Mountains,
+       have had their stormy birthdays since many of these beds
+       have been piled one above another, and there are but few
+       spots on the earth's surface where any number of them may be
+       found in their original order and natural position. When we
+       remember that Europe, which lies before us on the map as a
+       continent, was once an archipelago of islands,&mdash;that,
+       <span class="pagenum"><a id="page64"></a>[pg 64]</span> where the Pyrenees raise
+       their rocky barrier between France and Spain, the waters of
+       the Mediterranean and Atlantic met,&mdash;that, where the
+       British Channel flows, dry land united England and France,
+       and Nature in those days made one country of the lands
+       parted since by enmities deeper than the waters that run
+       between,&mdash;when we remember, in short, all the fearful
+       convulsions that have torn asunder the surface of the earth,
+       as if her rocky record had indeed been written on paper, we
+       shall find a new evidence of the intellectual unity which
+       holds together the whole physical history of the globe in
+       the fact that through all the storms of time the
+       investigator is able to trace one unbroken thread of thought
+       from the beginning to the present hour.</p>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/063-1.png"><img width="400"
+             src="images/063-1.png"
+             alt=
+           "SKELETON OF ANIMAL OF THE MIOCENE PERIOD."></a><br>
+        SKELETON OF ANIMAL OF THE MIOCENE PERIOD.
+    </div>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/063-2.png"><img width="300"
+             src="images/063-2.png"
+             alt=
+           "SKELETON OF ANIMAL OF THE PLIOCENE PERIOD."></a><br>
+        SKELETON OF ANIMAL OF THE PLIOCENE PERIOD.
+    </div>
+
+    <p>The tree is known by its fruits,&mdash;and the fruits of
+    chance are incoherence, incompleteness, unsteadiness, the
+    stammering utterance of blind, unreasoning force. A coherence
+    that binds all the geological ages in one chain, a stability of
+    purpose that completes in the beings born to-day an intention
+    expressed in the first creatures that swam in the Silurian
+    ocean or crept upon its shores, a steadfastness of thought,
+    practically recognized by man, if not acknowledged by him,
+    whenever he traces the intelligent connection between the facts
+    of Nature and combines them into what he is pleased to call his
+    system of Geology, or Zoölogy, or Botany,&mdash;these things
+    are not the fruits of chance or of an unreasoning force, but
+    the legitimate results of intellectual power. There is a
+    singular lack of logic, as it seems to me, in the views of the
+    materialistic naturalists. While they consider classification,
+    or, <span class="pagenum"><a id="page65"></a>[pg 65]</span> in other words, their
+       expression of the relations between animals or between
+       physical facts of any kind, as the work of their
+       intelligence, they believe the relations themselves to be
+       the work of physical causes. The more direct inference
+       surely is, that, if it requires an intelligent mind to
+       recognize them, it must have required an intelligent mind to
+       establish them. These relations existed before man was
+       created; they have existed ever since the beginning of time;
+       hence, what we call the classification of facts is not the
+       work of his mind in any direct original sense, but the
+       recognition of an intelligent action prior to his own
+       existence.</p>
+
+    <p>There is, perhaps, no part of the world, certainly none
+    familiar to science, where the early geological periods can be
+    studied with so much ease and precision as in the United
+    States. Along their northern borders, between Canada and the
+    United States, there runs the low line of hills known as the
+    Laurentian Hills. Insignificant in height, nowhere rising more
+    than fifteen hundred or two thousand feet above the level of
+    the sea, these are nevertheless the first mountains that broke
+    the uniform level of the earth's surface and lifted themselves
+    above the waters. Their low stature, as compared with that of
+    other more lofty mountain-ranges, is in accordance with an
+    invariable rule, by which the relative age of mountains may be
+    estimated. The oldest mountains are the lowest, while the
+    younger and more recent ones tower above their elders, and are
+    usually more torn and dislocated also. This is easily
+    understood, when we remember that all mountains and
+    mountain-chains are the result of upheavals, and that
+    <span class="pagenum"><a id="page66"></a>[pg 66]</span> the violence of the outbreak
+       must have been in proportion to the strength of the
+       resistance. When the crust of the earth was so thin that the
+       heated masses within easily broke through it, they were not
+       thrown to so great a height, and formed comparatively low
+       elevations, such as the Canadian hills or the mountains of
+       Bretagne and Wales. But in later times, when young, vigorous
+       giants, such as the Alps, the Himalayas, or, later still,
+       the Rocky Mountains, forced their way out from their fiery
+       prison-house, the crust of the earth was much thicker, and
+       fearful indeed must have been the convulsions which attended
+       their exit.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/066.png"><img width="500"
+             src="images/066.png"
+             alt="A PHYSICAL MAP OF THE UNITED STATES."></a><br>
+        A PHYSICAL MAP OF THE UNITED STATES.
+    </div>
+
+    <p>The Laurentian Hills form, then, a granite range, stretching
+    from Eastern Canada to the Upper Mississippi, and immediately
+    along its base are gathered the Azoic deposits, the first
+    stratified beds, in which the absence of life need not surprise
+    us, since they were <span class="pagenum"><a id="page67"></a>[pg 67]</span> formed beneath a heated
+       ocean. As well might we expect to find the remains of fish
+       or shells or crabs at the bottom of geysers or of boiling
+       springs, as on those early shores bathed by an ocean of
+       which the heat must have been so intense. Although, from the
+       condition in which we find it, this first granite range has
+       evidently never been disturbed by any violent convulsion
+       since its first upheaval, yet there has been a gradual
+       rising of that part of the continent; for the Azoic beds do
+       not lie horizontally along the base of the Laurentian Hills
+       in the position in which they must originally have been
+       deposited, but are lifted and rest against their slopes.
+       They have been more or less dislocated in this process, and
+       are greatly metamorphized by the intense heat to which they
+       must have been exposed. Indeed, all the oldest stratified
+       rocks have been baked by the prolonged action of heat.</p>
+
+    <p>It may be asked how the materials for those first stratified
+    deposits were provided. In later times, when an abundant and
+    various soil covered the earth, when every river brought down
+    to the ocean, not only its yearly tribute of mud or clay or
+    lime, but the débris of animals and plants that lived and died
+    in its waters or along its banks, when every lake and pond
+    deposited at its bottom in successive layers the lighter or
+    heavier materials floating in its waters and settling gradually
+    beneath them, the process by which stratified materials are
+    collected and gradually harden into rock is more easily
+    understood. But when the solid surface of the earth was only
+    just beginning to form, it would seem that the floating matter
+    in the sea can hardly have been in sufficient quantity to form
+    any extensive <span class="pagenum"><a id="page68"></a>[pg 68]</span> deposits. No doubt there was
+       some abrasion even of that first crust; but the more
+       abundant source of the earliest stratification is to be
+       found in the submarine volcanoes that poured their liquid
+       streams into the first ocean. At what rate these materials
+       would be distributed and precipitated in regular strata it
+       is impossible to determine; but that volcanic materials were
+       so deposited in layers is evident from the relative position
+       of the earliest rocks. I have already spoken of the
+       innumerable chimneys perforating the Azoic beds, narrow
+       outlets of Plutonic rock, protruding through the earliest
+       strata. Not only are such funnels filled with the
+       crystalline mass of granite that flowed through them in a
+       liquid state, but it has often poured over their sides,
+       mingling with the stratified beds around. In the present
+       state of our knowledge, we can explain such appearances only
+       by supposing that the heated materials within the earth's
+       crust poured out frequently, meeting little
+       resistance,&mdash;that they then scattered and were
+       precipitated in the ocean around, settling in successive
+       strata at its bottom,&mdash;that through such strata the
+       heated masses within continued to pour again and again,
+       forming for themselves the chimney-like outlets above
+       mentioned.</p>
+
+    <p>Such, then, was the earliest American land,&mdash;a long,
+    narrow island, almost continental in its proportions, since it
+    stretched from the eastern borders of Canada nearly to the
+    point where now the base of the Rocky Mountains meets the plain
+    of the Mississippi Valley. We may still walk along its ridge
+    and know that we tread upon the ancient granite that first
+    divided the waters into a northern and southern ocean; and if
+    our <span class="pagenum"><a id="page69"></a>[pg 69]</span> imaginations will carry us so
+       far, we may look down toward its base and fancy how the sea
+       washed against this earliest shore of a lifeless world. This
+       is no romance, but the bald, simple truth; for the fact that
+       this granite band was lifted out of the waters so early in
+       the history of the world, and has not since been submerged,
+       has, of course, prevented any subsequent deposits from
+       forming above it. And this is true of all the northern part
+       of the United States. It has been lifted gradually, the beds
+       deposited in one period being subsequently raised, and
+       forming a shore along which those of the succeeding one
+       collected, so that we have their whole sequence before us.
+       In regions where all the geological deposits (Silurian,
+       Devonian, carboniferous, permian, triassic, etc.) are piled
+       one upon another, and we can get a glimpse of their internal
+       relations only where some rent has laid them open, or where
+       their ragged edges, worn away by the abrading action of
+       external influences, expose to view their successive layers,
+       it must, of course, be more difficult to follow their
+       connection. For this reason the American continent offers
+       facilities to the geologist denied to him in the so-called
+       Old World, where the earlier deposits are comparatively
+       hidden, and the broken character of the land, intersected by
+       mountains in every direction, renders his investigation
+       still more difficult. Of course, when I speak of the
+       geological deposits as so completely unveiled to us here, I
+       do not forget the sheet of drift which covers the continent
+       from north to south, and which we shall discuss hereafter,
+       when I reach that part of my subject. But the drift is only
+       a superficial and recent addition to the soil, resting
+       loosely above <span class="pagenum"><a id="page70"></a>[pg 70]</span> the other geological
+       deposits, and arising, as we shall see, from very different
+       causes.</p>
+
+    <p>In this article I have intended to limit myself to a general
+    sketch of the formation of the Laurentian Hills with the Azoic
+    stratified beds resting against them. In the Silurian epoch
+    following the Azoic we have the first beach on which any life
+    stirred; it extended along the base of the Azoic beds, widening
+    by its extensive deposits the narrow strip of land already
+    upheaved. I propose ... to invite my readers to a stroll with
+    me along that beach.</p>
+
+    <p>With what interest do we look upon any relic of early human
+    history! The monument that tells of a civilization whose
+    hieroglyphic records we cannot even decipher, the slightest
+    trace of a nation that vanished and left no sign of its life
+    except the rough tools and utensils buried in the old site of
+    its towns or villages, arouses our imagination and excites our
+    curiosity. Men gaze with awe at the inscription on an ancient
+    Egyptian or Assyrian stone; they hold with reverential touch
+    the yellow parchment-roll whose dim, defaced characters record
+    the meagre learning of a buried nationality; and the
+    announcement, that for centuries the tropical forests of
+    Central America have hidden within their tangled growth the
+    ruined homes and temples of a past race, stirs the civilized
+    world with a strange, deep wonder.</p>
+
+    <p>To me it seems, that to look on the first land that was ever
+    lifted above the waste of waters, to follow the shore where the
+    earliest animals and plants were created when the thought of
+    God first expressed itself in organic forms, to hold in one's
+    hand a bit of stone from an old sea-beach, hardened into rock
+    thousands of <span class="pagenum"><a id="page71"></a>[pg 71]</span> centuries ago, and studded
+       with the beings that once crept upon its surface or were
+       stranded there by some retreating wave, is even of deeper
+       interest to men than the relies of their own race, for these
+       things tell more directly of the thoughts and creative acts
+       of God.</p>
+
+    <p>Standing in the neighborhood of Whitehall, near Lake George,
+    one may look along such a seashore, and see it stretching
+    westward and sloping gently southward as far as the eye can
+    reach. It must have had a very gradual slope, and the waters
+    must have been very shallow; for at that time no great
+    mountains had been uplifted, and deep oceans are always the
+    concomitants of lofty heights. We do not, however, judge of
+    this by inference merely; we have an evidence of the
+    shallowness of the sea in those days in the character of the
+    shells found in the Silurian deposits, which shows that they
+    belonged in shoal waters.</p>
+
+    <p>Indeed, the fossil remains of all times tell us almost as
+    much of the physical condition of the world at different epochs
+    as they do of its animal and vegetable population. When
+    Robinson Crusoe first caught sight of the footprint on the
+    sand, he saw in it more than the mere footprint, for it spoke
+    to him of the presence of men on his desert island. We walk on
+    the old geological shores, like Crusoe along his beach, and the
+    footprints we find there tell us, too, more than we actually
+    see in them. The crust of our earth is a great cemetery, where
+    the rocks are tombstones on which the buried dead have written
+    their own epitaphs. They tell us not only who they were and
+    when and where they lived, but much also of the circumstances
+    under which they lived. We ascertain the prevalence of certain
+    physical <span class="pagenum"><a id="page72"></a>[pg 72]</span> conditions at special epochs
+       by the presence of animals and plants whose existence and
+       maintenance required such a state of things, more than by
+       any positive knowledge respecting it. Where we find the
+       remains of quadrupeds corresponding to our ruminating
+       animals, we infer not only land, but grassy meadows also,
+       and an extensive vegetation; where we find none but marine
+       animals, we know the ocean must have covered the earth; the
+       remains of large reptiles, representing, though in gigantic
+       size, the half aquatic, half terrestrial reptiles of our own
+       period, indicate to us the existence of spreading marshes
+       still soaked by the retreating waters; while the traces of
+       such animals as live now in sand and shoal waters, or in
+       mud, speak to us of shelving sandy beaches and of mud-flats.
+       The eye of the Trilobite tells us that the sun shone on the
+       old beach where he lived; for there is nothing in nature
+       without a purpose, and when so complicated an organ was made
+       to receive the light, there must have been light to enter
+       it. The immense vegetable deposits in the Carboniferous
+       period announce the introduction of an extensive terrestrial
+       vegetation; and the impressions left by the wood and leaves
+       of the trees show that these first forests must have grown
+       in a damp soil and a moist atmosphere. In short, all the
+       remains of animals and plants hidden in the rocks have
+       something to tell of the climatic conditions and the general
+       circumstances under which they lived, and the study of
+       fossils is to the naturalist a thermometer by which he reads
+       the variations of temperature in past times, a plummet by
+       which he sounds the depths of the ancient oceans,&mdash;a
+       register, in fact, of all the important physical changes the
+       earth has undergone.</p><span class="pagenum"><a name=
+       "page73"
+       id="page73"></a>[pg 73]</span>
+
+    <p>But although the animals of the early geological deposits
+    indicate shallow seas by their similarity to our shoal-water
+    animals, it must not be supposed that they are by any means the
+    same. On the contrary, the old shells, crustacea, corals, etc.,
+    represent types which have existed in all times with the same
+    essential structural elements, but under different specific
+    forms in the several geological periods. And here it may not be
+    amiss to say something of what are called by naturalists
+    <i>representative types</i>.</p>
+
+    <p>The statement that different sets of animals and plants have
+    characterized the successive epochs is often understood as
+    indicating a difference of another kind than that which
+    distinguishes animals now living in different parts of the
+    world. This is a mistake. There are so-called representative
+    types all over the globe, united to each other by structural
+    relations and separated by specific differences of the same
+    kind as those that unite and separate animals of different
+    geological periods. Take, for instance, mud-flats or sandy
+    shores in the same latitudes of Europe and America; we find
+    living on each, animals of the same structural character and of
+    the same general appearance, but with certain specific
+    differences, as of color, size, external appendages, etc. They
+    represent each other on the two continents. The American
+    wolves, foxes, bears, rabbits, are not the same as the
+    European, but those of one continent are as true to their
+    respective types as those of the other; under a somewhat
+    different aspect they represent the same groups of animals. In
+    certain latitudes, or under conditions of nearer proximity,
+    these differences may be less marked. It is well
+          <span class="pagenum"><a id="page74"></a>[pg 74]</span> known that there is a great
+       monotony of type, not only among animals and plants, but in
+       the human races also, throughout the Arctic regions; and
+       some animals characteristic of the high North reappear under
+       such identical forms in the neighborhood of the snow-fields
+       in lofty mountains, that to trace the difference between the
+       ptarmigans, rabbits, and other gnawing animals of the Alps,
+       for instance, and those of the Arctics, is among the most
+       difficult problems of modern science.</p>
+
+    <p>And so it is also with the animated world of past ages; in
+    similar deposits of sand, mud, or lime, in adjoining regions of
+    the same geological age, identical remains of animals and
+    plants may be found; while at greater distances, but under
+    similar circumstances, representative species may occur. In
+    very remote regions, however, whether the circumstances be
+    similar or dissimilar, the general aspect of the organic world
+    differs greatly, remoteness in space being thus in some measure
+    an indication of the degree of affinity between different
+    faunæ. In deposits of different geological periods immediately
+    following each other, we sometimes find remains of animals and
+    plants so closely allied to those of earlier or later periods
+    that at first sight the specific differences are hardly
+    discernible. The difficulty of solving these questions, and of
+    appreciating correctly the differences and similarities between
+    such closely allied organisms, explains the antagonistic views
+    of many naturalists respecting the range of existence of
+    animals, during longer or shorter geological periods; and the
+    superficial way in which discussions concerning the transition
+    of species are carried on, is mainly owing to an ignorance of
+    the <span class="pagenum"><a id="page75"></a>[pg 75]</span> conditions above alluded to.
+       My own personal observation and experience in these matters
+       have led me to the conviction that every geological period
+       has had its own representatives, and that no single species
+       has been repeated in successive ages.</p>
+
+    <p>The laws regulating the geographical distribution of
+    animals, and their combination into distinct zoölogical
+    provinces called faunæ, with definite limits, are very
+    imperfectly understood as yet; but so closely are all things
+    linked together from the beginning that I am convinced we shall
+    never find the clew to their meaning till we carry on our
+    investigations in the past and the present simultaneously. The
+    same principle according to which animal and vegetable life is
+    distributed over the surface of the earth now, prevailed in the
+    earliest geological periods. The geological deposits of all
+    times have had their characteristic faunæ under various zones,
+    their zoölogical provinces presenting special combinations of
+    animal and vegetable life over certain regions, and their
+    representative types reproducing in different countries, but
+    under similar latitudes, the same groups with specific
+    differences.</p>
+
+    <p>Of course, the nearer we approach the beginning of organic
+    life, the less marked do we find the differences to be, and for
+    a very obvious reason. The inequalities of the earth's surface,
+    her mountain-barriers protecting whole continents from the
+    Arctic winds, her open plains exposing others to the full force
+    of the polar blasts, her snug valleys and her lofty heights,
+    her tablelands and rolling prairies, her river-systems and her
+    dry deserts, her cold ocean-currents pouring down from the high
+    North on some of her shores, while warm <span class=
+    "pagenum"><a id="page76"></a>[pg 76]</span> ones from tropical seas carry
+       their softer influence to others,&mdash;in short, all the
+       contrasts in the external configuration of the globe, with
+       the physical conditions attendant upon them, are naturally
+       accompanied by a corresponding variety in animal and
+       vegetable life.</p>
+
+    <p>But in the Silurian age, when there were no elevations
+    higher than the Canadian hills, when water covered the face of
+    the earth, with the exception of a few isolated portions lifted
+    above the almost universal ocean, how monotonous must have been
+    the conditions of life! And what should we expect to find on
+    those first shores? If we are walking on a sea-beach to-day, we
+    do not look for animals that haunt the forests or roam over the
+    open plains, or for those that live in sheltered valleys or in
+    inland regions or on mountain-heights. We look for Shells, for
+    Mussels and Barnacles, for Crabs, for Shrimps, for Marine
+    Worms, for Star-Fishes and Sea-Urchins, and we may find here
+    and there a fish stranded on the sand or tangled in the
+    seaweed.</p>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/076.png"><img width="400"
+             src="images/076.png"
+             alt="Hills."></a>
+    </div><span class="pagenum"><a id="page77"></a>[pg 77]</span>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p>
+
+    <h2>SOME RECORDS OF THE ROCKS</h2>
+
+    <h4 class="sc">(From A First Book in Geology.)</h4>
+
+    <h3><span class="sc">By</span> N.S. SHALER, S.D.<a id="footnotetag1"></a><a href="#footnote1"><sup>1</sup></a></h3>
+    <hr class="short">
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/077.png"><img width="250"
+             src="images/077.png"
+             alt="Figures on Rocks."></a>
+    </div>
+
+    <p>The geologist cannot find his way back in the record of the
+    great stone book, to the far-off day when life began. The
+    various changes that come over rocks from the action of heat,
+    of water, and of pressure, have slowly modified these ancient
+    beds, so that they no longer preserve the frames of the animals
+    that were buried in them.</p>
+
+    <p>These old rocks, which are so changed that we cannot any
+    longer make sure that any animals lived in them, are called the
+    "archæan," which is Greek for ancient. They were probably mud
+    and sand and limestone when first made, but they have been
+    changed to mica schists, gneiss, granite, marble, and other
+    crystalline rocks. When any rock becomes crystalline, the
+    fossils dissolve and disappear, as coins lose their stamp
+    <span class="pagenum"><a id="page78"></a>[pg 78]</span> and form when they are melted
+       in the jeweller's gold-pot.</p>
+
+    <p>These ancient rocks that lie deepest in the earth are very
+    thick, and must have taken a great time in building; great
+    continents must have been worn down by rain and waves in order
+    to supply the waste out of which they were made. It is
+    tolerably certain that they took as much time during their
+    making as has been required for all the other times since they
+    were formed. During the vast ages of this archæan the life of
+    our earth began to be. We first find many certain evidences of
+    life in the rocks which lie on top of the archæan rock, and are
+    known as the Cambriani and Silurian periods. There we have
+    creatures akin to our corals and crabs and worms, and others
+    that are the distant kindred of the cuttle-fishes and of our
+    lamp-shells. There were no backboned animals, that is to say,
+    no land mammals, reptiles, or fishes at this stage of the
+    earth's history. It is not likely that there was any land life
+    except of plants and those forms like the lowest ferns, and
+    probably mosses. Nor is it likely that there were any large
+    continents as at the present time, but rather a host of islands
+    lying where the great lands now are, the budding tops of the
+    continents just appearing above the sea.</p>
+
+    <p>Although the life of this time was far simpler than at the
+    present day, it had about as great variety as we would find on
+    our present sea-floors. There were as many different species
+    living at the same time on a given surface.</p>
+
+    <p>The Cambrian and Silurian time&mdash;the time before the
+    coming of the fishes&mdash;must have endured for
+          <span class="pagenum"><a id="page79"></a>[pg 79]</span> many million years without
+       any great change in the world. Hosts of species lived and
+       died; half a dozen times or more the life of the earth was
+       greatly changed. New species came much like those that had
+       gone before, and only a little gain here and there was
+       perceptible at any time. Still, at the end of the Silurian,
+       the life of the world had climbed some steps higher in
+       structure and in intelligence.</p>
+
+    <div class="figright"
+         style="width:250px;">
+        <a href="images/079.png"><img width="250"
+             src="images/079.png"
+             alt="FIG. 1. NORTH AMERICA IN CAMBRIAN TIME."></a><br>
+        FIG. 1. NORTH AMERICA IN CAMBRIAN TIME.
+    </div>
+
+    <p>The next set of periods is known as the Devonian. It is
+    marked by the rapid extension of the fishes; for, although the
+    fishes began in the uppermost Silurian, they first became
+    abundant in this time. These, the first strong-jawed tyrants of
+    the sea, came all at once, like a rush of the old Norman
+    pirates into the peaceful seas of Great Britain. They made a
+    lively time among the sluggish beings of that olden sea.
+    Creatures that were able to meet feebler enemies were swept
+    away or compelled to undergo great changes, and all the life of
+    the oceans seems to have a spur given to it by these
+    quicker-formed and quicker-willed animals. In this Devonian
+    section of our rocks we have proofs that the lands were
+    extensively covered with forests of low fern trees, and we find
+    the first trace of air-breathing animals in certain insects
+    akin to our dragon-flies. In this stage of the earth's history
+    the fishes grew constantly more plentiful, and the seas had a
+    great <span class="pagenum"><a id="page80"></a>[pg 80]</span> abundance of corals and
+       crinoids. Except for the fishes, there were no very great
+       changes in the character of the life from that which existed
+       in the earlier time of the Cambrian and Silurian. The
+       animals are constantly changing, but the general nature of
+       the life remains the same as in the earlier time.</p>
+
+    <div class="figleft"
+         style="width:350px;">
+        <a href="images/080.png"><img width="350"
+             src="images/080.png"
+             alt=
+           "FIG. 2. RANICEPS LYELLI--COAL TIME SALAMANDER."></a><br>
+        FIG. 2. RANICEPS LYELLI&mdash;COAL TIME SALAMANDER.
+    </div>
+
+    <p>In the Carboniferous or coal-bearing age, we have the second
+    great change in the character of the life on the earth. Of the
+    earlier times, we have preserved only the rocks formed in the
+    seas. But rarely do we find any trace of the land life or even
+    of the life that lived along the shores. In this Carboniferous
+    time, however, we have very extensive sheets of rocks which
+    were formed in swamps in the way shown in the earlier part of
+    this book. They constitute our coal-beds, which, though much
+    worn away by rain and sea, still cover a large part of the land
+    surface. These beds of coal grew in the air, and, although the
+    swamps where they were formed had very little animal life in
+    them, we find some fossils which tell us that the life of the
+    land was making great progress; there are new insects,
+    including beetles, cockroaches, spiders, and scorpions, and,
+    what is far more important, there are some air-breathing,
+    back-boned animals, akin to the salamanders and water-dogs of
+    the present day. These were nearly as large as alligators, and
+    of much the same shape, but they were <span class=
+    "pagenum"><a id="page81"></a>[pg 81]</span> probably born from the egg in
+       the shape of tadpoles and lived for a time in the water as
+       our young frogs, toads, and salamanders do. This is the
+       first step upwards from the fishes to land vertebrates; and
+       we may well be interested in it, for it makes one most
+       important advance in creatures through whose lives our own
+       existence became possible. Still, these ancient woods of the
+       coal period must have had little of the life we now
+       associate with the forests; there were still no birds, no
+       serpents, no true lizards, no suck-giving animals, no
+       flowers, and no fruits. These coal-period forests were
+       sombre wastes of shade, with no sound save those of the
+       wind, the thunder, and the volcano, or of the running
+       streams and the waves on the shores.</p>
+
+    <p>In the seas of the Carboniferous time, we notice that the
+    ancient life of the earth is passing away. Many creatures, such
+    as the trilobites, die out, and many other forms such as the
+    crinoids or sea lilies become fewer in kind and of less
+    importance. These marks of decay in the marine life continue
+    into the beds just after the Carboniferous, known as the
+    Permian, which are really the last stages of the coal-bearing
+    period.</p>
+
+    <p>When with the changing time we pass to the beds known as the
+    Triassic, which were made just after the close of the
+    Carboniferous time, we find the earth undergoing swift changes
+    in its life. The moist climate and low lands that caused the
+    swamps to grow so rapidly have ceased to be, and in their place
+    we appear to have warm, dry air, and higher lands.</p>
+
+    <p>On these lands of the Triassic time the air-breathing
+    <span class="pagenum"><a id="page82"></a>[pg 82]</span> life made very rapid
+       advances. The plants are seen to undergo considerable
+       changes. The ferns no longer make up all the forests, but
+       trees more like the pines began to abound, and insects
+       became more plentiful and more varied.</p>
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/082.png"><img width="200"
+             src="images/082.png"
+             alt=
+           "CYCAS CIRCINALIS, AKIN TO HIGHEST PLANTS OF COAL TIME."></a>
+
+        <p>FIG. 3. CYCAS CIRCINALIS, AKIN TO HIGHEST PLANTS OF COAL
+        TIME.</p>
+    </div>
+
+    <p>Hitherto the only land back-boned animal was akin to our
+    salamanders. Now we have true lizards in abundance, many of
+    them of large size. Some of them were probably plant-eaters,
+    but most were flesh-eaters; some seem to have been tenants of
+    the early swamps, and some dwelt in the forests.</p>
+
+    <p>The creatures related to the salamanders have increased in
+    the variety of their forms to a wonderful extent. We know them
+    best by the tracks which they have left on the mud stones
+    formed on the borders of lakes or the edge of the sea. In some
+    places these footprints are found in amazing numbers and
+    perfection. The best place for them is in the Connecticut
+    Valley, near Turner's Falls, Mass. At this point the red
+    sandstone and shale beds, which are composed of thin layers
+    having a total thickness of several hundred feet, are often
+    stamped over by these footprints like the mud of a barnyard.
+    From the little we can determine from these footprints, the
+    creatures seem to have been somewhat related to our frogs, but
+    they generally had tails, and, though provided with four legs,
+    were in the habit of walking on the hind ones alone like the
+    <span class="pagenum"><a id="page83"></a>[pg 83]</span> kangaroo. A few of these
+       tracks are shown in the figure on this page.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/083-1.png"><img width="500"
+             src="images/083-1.png"
+             alt=
+           "FIG. 4. FOOT-PRINTS, CONNECTICUT SANDSTONES."></a><br>
+        FIG. 4. FOOT-PRINTS, CONNECTICUT SANDSTONES.
+    </div>
+
+    <p>These strange creatures were of many different species. Some
+    of them must have been six or seven feet high, for their steps
+    are as much as three feet apart, and seem to imply a creature
+    weighing several hundred pounds. Others were not bigger than
+    robins. Strangely enough, we have never found their bones nor
+    the creatures on which they fed, and but for the formation of a
+    little patch of rocks here and there we should not have had
+    even these footprints to prove to us that such creatures had
+    lived in the Connecticut Valley in this far-off time.</p>
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/083-2.png"><img width="200"
+             src="images/083-2.png"
+             alt="FIG. 5. FOOT-PRINT,"></a>
+
+        <p>FIG. 5. FOOT-PRINT, TURNER'S FALLS.</p>
+    </div>
+
+    <p>But these wonderful forms are less interesting than two or
+    three little fossil jaw-bones that prove to us that in this
+    Triassic time the earth now bore another animal more akin to
+    ourselves, in the shape of a little creature that gave suck to
+    its young. Once more life takes a long upward step in this
+    little opossum-like <span class="pagenum"><a id="page84"></a>[pg 84]</span> animal, perhaps the first
+       creature whose young was born alive. These little creatures
+       called Microlestes or Dromatherium, of which only one or two
+       different but related species have been found in England and
+       in North Carolina, appear to have been insect-eaters of
+       about the size and shape of the Australian creature shown in
+       Fig. 7. So far we know it in but few
+       specimens,&mdash;altogether only an ounce or two of
+       bones,&mdash;but they are very precious monuments of the
+       past.</p>
+
+    <div class="figleft"
+         style="width:500px;">
+        <a href="images/084-1.png"><img width="500"
+             src="images/084-1.png"
+             alt=
+           "FIG. 6. DROMATHERIUM SYLVESTRE AND TEETH OF MICROLESTES ANTIQUUS."></a><br>
+        FIG. 6. DROMATHERIUM SYLVESTRE AND TEETH OF MICROLESTES
+        ANTIQUUS.
+    </div>
+
+    <p>In this Triassic time the climate appears to have been
+    rather dry, for in it we have many extensive deposits of salt
+    formed by the evaporation of closed lakes, of seas, such as are
+    now forming on the bottom of the Dead Sea, and the Great Salt
+    Lake of Utah, and a hundred or more other similar basins of the
+    present day.</p>
+
+    <div class="figright"
+         style="width:300px;">
+        <a href="images/084-2.png"><img width="300"
+             src="images/084-2.png"
+             alt="FIG. 7. MYRMECOBIUS."></a><br>
+        FIG. 7. MYRMECOBIUS.
+    </div>
+
+    <p>In the sea animals of this time we find many changes.
+    Already some of the giant lizard-like animals, which first took
+    shape on the land, are becoming swimming-animals. They changed
+    their feet to paddles, which, with the help of a flattened
+    tail, force them through the water.</p>
+
+    <p>The fishes on which these great swimming lizards preyed are
+    more like the fishes of our present day than <span class=
+    "pagenum"><a id="page85"></a>[pg 85]</span> they were before. The
+       trilobites are gone, and of the crinoids only a remnant is
+       left. Most of the corals of the earlier days have
+       disappeared, but the mollusks have not changed more than
+       they did at several different times in the earliest stages
+       of the earth's history.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/085.png"><img width="500"
+             src="images/085.png"
+             alt="FIG. 8. ICHTHYOSAURUS AND PLESIOSAURUS."></a><br>
+        FIG. 8. ICHTHYOSAURUS AND PLESIOSAURUS.
+    </div>
+
+    <p>After the Trias comes a long succession of ages in which the
+    life of the world is steadily advancing to higher and higher
+    planes; but for a long time there is no such startling change
+    as that which came in the passage from the coal series of rocks
+    to the Trias. This long set of periods is known to geologists
+    as the age of reptiles. It is well named, for the kindred of
+    the lizards then had the control of the land. There were then
+    none of our large fish to dispute their control, so they shaped
+    themselves to suit all the occupations that could give them a
+    chance for a living. Some remained beasts of prey like our
+    alligators, but grew to larger size; some took to eating the
+    plants, and came to walk on their four legs as our ordinary
+    beasts do, no longer dragging themselves on their bellies as do
+    the lizard and alligator, their lower kindred. Others became
+    flying creatures like our bats, only vastly larger, often
+    <span class="pagenum"><a id="page86"></a>[pg 86]</span> with a spread of wing of
+       fifteen or twenty feet. Yet others, even as strangely
+       shaped, dwelt with the sharks in the sea.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/086.png"><img width="500"
+             src="images/086.png"
+             alt="FIG. 9. REPTILES OF JURASSIC PERIOD."></a><br>
+        FIG. 9. REPTILES OF JURASSIC PERIOD.
+    </div>
+
+    <p>In this time of the earth's history we have the first
+    bird-like forms. They were feathered creatures, with bills
+    carrying true teeth, and with strong wings; but they were
+    reptiles in many features, having long, pointed tails such as
+    none of our existing birds have. They show us that the birds
+    are the descendants of reptiles, coming off from them as a
+    branch does from the parent tree. The tortoises began in this
+    series of rocks. At first they are marine or swimming forms,
+    the box-turtles coming later. Here too begin many of the higher
+    insects. Creatures like moths and bees appear, and the forests
+    are enlivened with all the important kinds of insects, though
+    the species were very different from those now living.</p>
+
+    <p>In the age of reptiles the plants have made a considerable
+    advance. Palms are plenty; forms akin to our pines and firs
+    abound, and the old flowerless group of ferns begins to shrink
+    in size, and no longer spreads its feathery foliage over all
+    the land as before. Still <span class="pagenum"><a name=
+    "page87"
+       id="page87"></a>[pg 87]</span> there were none of our common
+       broad-leaved trees; the world had not yet known the oaks,
+       birches, maples, or any of our hard-wood trees that lose
+       their leaves in autumn; nor were the flowering plants, those
+       with gay blossoms, yet on the earth. The woods and fields
+       were doubtless fresh and green, but they wanted the grace of
+       blossoms, plants, and singing-birds. None of the animals
+       could have had the social qualities or the finer instincts
+       that are so common among animals of the present day. There
+       were probably no social animals like our ants and bees, no
+       merry singing creatures; probably no forms that went in
+       herds. Life was a dull round of uncared-for birth, cruel
+       self-seeking, and of death. The animals at best were clumsy,
+       poorly-endowed creatures, with hardly more intelligence than
+       our alligators.</p>
+
+    <p>The little thread of higher life begun in the Microlestes
+    and Dromatherium, the little insect-eating mammals of the
+    forest, is visible all through this time. It held in its warm
+    blood the powers of the time to come, but it was an
+    insignificant thing among the mighty cold-blooded reptiles of
+    these ancient lands. There are several species of them, but
+    they are all small, and have no chance to make headway against
+    the older masters of the earth.</p>
+
+    <p>The Jurassic or first part of the reptilian time shades
+    insensibly into the second part, called the Cretaceous, which
+    immediately follows it. During this period the lands were
+    undergoing perpetual changes; rather deep seas came to cover
+    much of the land surfaces, and there is some reason to believe
+    that the climate of the earth became much colder than it had
+    been, at least in those <span class="pagenum"><a id="page88"></a>[pg 88]</span> regions where the great
+       reptiles had flourished. It may be that it is due to a
+       colder climate that we owe the rapid passing away of this
+       gigantic reptilian life of the previous age. The reptiles,
+       being cold-blooded, cannot stand even a moderate winter
+       cold, save when they are so small that they can crawl deep
+       into crevices in the rocks to sleep the winter away, guarded
+       from the cold by the warmth of the earth. At any rate these
+       gigantic animals rapidly ceased to be, so that by the middle
+       of the Cretaceous period they were almost all gone, except
+       those that inhabited the sea; and at the end of this time
+       they had shrunk to lizards in size. The birds continue to
+       increase and to become more like those of our day; their
+       tails shrink away, their long bills lose their teeth; they
+       are mostly water-birds of large size, and there are none of
+       our songsters yet; still they are for the first time perfect
+       birds, and no longer half-lizard in their nature.</p>
+
+    <p>The greatest change in the plants is found in the coming of
+    the broad-leaved trees belonging to the families of our oaks,
+    maples, etc. Now for the first time our woods take on their
+    aspect of to-day; pines and other cone-bearers mingle with the
+    more varied foliage of nut-bearing or large-seeded trees.
+    Curiously enough, we lose sight of the little mammals of the
+    earlier time. This is probably because there is very little in
+    the way of land animals of this period preserved to us. There
+    are hardly any mines or quarries in the beds of this age to
+    bring these fossils to light. In the most of the other rocks
+    there is more to tempt man to explore them for coal ores or
+    building stones.</p>
+
+    <p>In passing from the Cretaceous to the Tertiary, we
+    <span class="pagenum"><a id="page89"></a>[pg 89]</span> enter upon the threshold of
+       our modern world. We leave behind all the great wonders of
+       the old world, the gigantic reptiles, the forests of tree
+       ferns, the seas full of ammonites and belemnites, and come
+       among the no less wonderful but more familiar modern forms.
+       We come at once into lands and seas where the back-boned
+       animals are the ruling beings. The reptiles have shrunk to a
+       few low forms,&mdash;the small lizards, the crocodiles and
+       alligators, the tortoises and turtles, and, as if to mark
+       more clearly the banishment of this group from their old
+       empire, the serpents, which are peculiarly degraded forms of
+       reptiles which have lost the legs they once had, came to be
+       the commonest reptiles of the earth.</p>
+
+    <p>The first mammals that have no pouches now appear. In
+    earlier times, the suck-giving animals all belonged to the
+    group that contains our opossums, kangaroos, etc. These
+    creatures are much lower and feebler than the mammals that have
+    no pouches. Although they have probably been on the earth two
+    or three times as long as the higher mammals, they have never
+    attained any eminent success whatever; they cannot endure cold
+    climates; none of them are fitted for swimming as are the seals
+    and whales, or for flying as the bats, or for burrowing as the
+    moles; they are dull, weak things, which are not able to
+    contend with their stronger, better-organized, higher kindred.
+    They seem not only weak, but unable to fit themselves to many
+    different kinds of existence.</p>
+
+    <p>In the lower part of the Tertiary rocks, we find at once a
+    great variety of large beasts that gave suck to their young. It
+    is likely that these creatures had come <span class=
+    "pagenum"><a id="page90"></a>[pg 90]</span> into existence in a somewhat
+       earlier time in other lands, where we have not been able to
+       study the fossils; for to make their wonderful forms slowly,
+       as we believe them to have been made, would require a very
+       long time. It is probable that during the Cretaceous time,
+       in some land where we have not yet had a chance to study the
+       rocks, these creatures grew to their varied forms, and that
+       in the beginning of the Tertiary time, they spread into the
+       regions where we find their bones.</p>
+
+    <p>Beginning with the Tertiary time, we find these lower
+    kinsmen of man, through whom man came to be. The mammals were
+    marked by much greater simplicity and likeness to each other
+    than they now have. There were probably no monkeys, no horses,
+    no bulls, no sheep, no goats, no seals, no whales, and no bats.
+    All these animals had many-fingered feet. There were no cloven
+    feet like those of our bulls, and no solid feet as our horses
+    have. Their brains, which by their size give us a general idea
+    of the intelligence of the creature, are small; hence we
+    conclude that these early mammals were less intelligent than
+    those of our day.</p>
+
+    <p>It would require volumes to trace the history of the growth
+    of these early mammals, and show how they, step by step, came
+    to their present higher state. We will take only one of the
+    simplest of these changes, which happens to be also the one
+    which we know best. This is the change that led to the making
+    of our common horses, which seem to have been brought into life
+    on the continent of North America. The most singular thing
+    about our horses is that the feet have but one large toe or
+    finger, the hoof, the hard covering of which is the nail of
+    that extremity. Now it seems <span class="pagenum"><a name=
+    "page91"
+       id="page91"></a>[pg 91]</span> hard to turn the weak,
+       five-fingered feet of the animals of the lower
+       Tertiary&mdash;feet which seem to be better fitted for
+       tree-climbing than anything else&mdash;into feet such as we
+       find in the horse. Yet the change is brought about by easy
+       stages that lead the successive creatures from the weak and
+       loose-jointed foot of the ancient forms to the solid,
+       single-fingered horse's hoof, which is wonderfully
+       well-fitted for carrying a large beast at a swift speed, and
+       is so strong a weapon of defence that an active donkey can
+       kill a lion with a well-delivered kick.</p>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/091.png"><img width="600"
+             src="images/091.png"
+             alt="FIG. 10. FEET OF TERTIARY MAMMALS."></a><br>
+        FIG. 10. FEET OF TERTIARY MAMMALS.
+    </div>
+
+    <p>The oldest of these creatures that lead to the horses is
+    called <i>Eohippus</i> or beginning horse. This fellow had on
+    the forefeet four large toes, each with a small hoof and fifth
+    imperfect one, which answered to the thumb. The hind feet had
+    gone further in the change, for they each had but three toes,
+    each with hoofs, the middle-toed hoof larger and longer than
+    the others. A little later toward our day we find another
+    advance in the <i>Orohippus</i>, when the little imperfect
+    thumb has disappeared, and there are only four toes on the
+    forefeet and three on the hind.</p><span class=
+    "pagenum"><a id="page92"></a>[pg 92]</span>
+
+    <p>Yet later we have the <i>Mesohippus</i> or half-way horse.
+    There are still three toes on the hind foot, but one more of
+    the fingers of the forefeet has disappeared. This time it is
+    the little finger that goes, leaving only a small bone to show
+    that its going was by a slow shrinking. The creature now has
+    three little hoofs on each of its feet.</p>
+
+    <p>Still nearer our own time comes the <i>Miohippus</i>, which
+    shows the two side hoofs on each foot shrinking up so that they
+    do not touch the ground, but they still bear little hoofs.
+    Lastly, about the time of man's coming on the earth, appears
+    his faithful servant, the horse, in which those little side
+    hoofs have disappeared, leaving only two little "splint" bones
+    to mark the place where these side hoofs belong. Thus, step by
+    step, our horses' feet were built up; while these parts were
+    changing, the other parts of the animals were also slowly
+    altering. They were at first smaller than our
+    horses,&mdash;some of them not as large as an ordinary
+    Newfoundland dog; others as small as foxes.</p>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/092.png"><img width="600"
+             src="images/092.png"
+             alt="FIG. 11. DEVELOPMENT OF HORSES'S FOOT."></a><br>
+        FIG. 11. DEVELOPMENT OF HORSES'S FOOT.
+    </div>
+
+    <p>As if to remind us of his old shape, our horses now and
+    then, but rarely, have, in place of the little splint bones
+    above the hoof, two smaller hoofs, just like the
+          <span class="pagenum"><a id="page93"></a>[pg 93]</span> foot of <i>Miohippus</i>.
+       Sometimes these are about the size of a silver dollar, on
+       the part that receives the shoe when horses are shod.</p>
+
+    <p>In this way, by slow-made changes, the early mammals pass
+    into the higher. Out of one original part are made limbs as
+    different as the feet of the horse, the wing of a bat, the
+    paddle of a whale, and the hand of man. So with all the parts
+    of the body the forms change to meet the different uses to
+    which they are put.</p>
+
+    <p>At the end of this long promise, which was written in the
+    very first animals, comes man himself, in form closely akin to
+    the lower animals, but in mind immeasurably apart from them. We
+    can find every part of man's body in a little different shape
+    in the monkeys, but his mind is of a very different quality.
+    While his lower kindred cannot be made to advance in
+    intelligence any more than man himself can grow a horse's foot
+    or a bat's wing, he is constantly going higher and higher in
+    his mental and moral growth.</p>
+
+    <p>So far we have found but few traces of man that lead us to
+    suppose that he has been for a long geological time on the
+    earth, yet there is good evidence that he has been here for a
+    hundred thousand years or more. It seems pretty clear that he
+    has changed little in his body in all these thousands of
+    generations. The earliest remains show us a large-brained
+    creature, who used tools and probably had already made a
+    servant of fire, which so admirably aids him in his work.</p>
+
+    <p>Besides the development of this wonderful series of animals,
+    that we may call in a certain way our kindred, there have been
+    several other remarkable advances in this Tertiary time, this
+    age of crowning wonders in the <span class=
+       "pagenum"><a id="page94"></a>[pg 94]</span> earth's history. The birds
+       have gone forward very rapidly; it is likely that there were
+       no songsters at the first part of this period, but these
+       singing birds have developed very rapidly in later times.
+       Among the insects the most remarkable growth is among the
+       ants, the bees, and their kindred. These creatures have very
+       wonderful habits; they combine together for the making of
+       what we may call states, they care for their young, they
+       wage great battles, they keep slaves, they domesticate other
+       insects, and in many ways their acts resemble the doings of
+       man. Coming at about the same time as man, these
+       intellectual insects help to mark this later stage of the
+       earth as the intellectual period in its history. Now for the
+       first time creatures are on the earth which can form
+       societies and help each other in the difficult work of
+       living.</p>
+
+    <p>Among the mollusks, the most important change is in the
+    creation of the great, strong swimming squids, the most
+    remarkable creatures of the sea. Some of these have arms that
+    can stretch for fifty feet from tip to tip.</p>
+
+    <p>Among the plants, the most important change has been in the
+    growth of flowering plants, which have been constantly becoming
+    more plenty, and the plants which bear fruits have also become
+    more numerous. The broad-leaved trees seem to be constantly
+    gaining on the forests of narrow-leaved cone-bearers, which had
+    in an earlier day replaced the forests of ferns.</p>
+
+    <p>In these Tertiary ages, as in the preceding times of the
+    earth, the lands and seas were much changed in their shape. It
+    seems that in the earlier ages the land had been mostly in the
+    shape of large islands grouped <span class=
+       "pagenum"><a id="page95"></a>[pg 95]</span> close together where the
+       continents now are. In this time, these islands grew
+       together to form the united lands of Europe, Asia, Africa,
+       Australia, and the twin American continents; so that, as
+       life rose higher, the earth was better fitted for it. Still
+       there were great troubles that it had to undergo. There were
+       at least two different times during the Tertiary age termed
+       glacial periods, times when the ice covered a large part of
+       the northern continents, compelling life of all sorts to
+       abandon great regions, and to find new places in more
+       southern lands. Many kinds of animals and plants seem to
+       have been destroyed in these journeys; but these times of
+       trial, by removing the weaker and less competent creatures,
+       made room for new forms to rise in their places. All advance
+       in nature makes death necessary, and this must come to races
+       as well as to individuals if the life of the world is to go
+       onward and upward.</p>
+
+    <p>Looking back into the darkened past, of which we yet know
+    but little compared with what we would like to know, we can see
+    the great armies of living beings led onward from victory to
+    victory toward the higher life of our own time. Each age sees
+    some advance, though death overtakes all its creatures. Those
+    that escape their actual enemies or accident, fall a prey to
+    old age: volcanoes, earthquakes, glacial periods, and a host of
+    other violent accidents sweep away the life of wide regions,
+    yet the host moves on under a control that lies beyond the
+    knowledge of science. Man finds himself here as the crowning
+    victory of this long war. For him all this life appears to have
+    striven. In his hands lies the profit of all its toil and pain.
+    Surely <span class="pagenum"><a id="page96"></a>[pg 96]</span> this should make us feel that
+       our duty to all these living things, that have shared in the
+       struggle that has given man his elevation, is great, but
+       above all, great is our duty to the powers that have been
+       placed in our bodies and our minds.</p>
+
+    <div class="figcenter"
+         style="width:500px">
+        <a href="images/096.png"><img width="500"
+             src="images/096.png"
+             alt="A GLACIER."></a><br>
+        A GLACIER.
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="page97"></a>[pg 97]</span>
+
+    <h2>THE PITCH LAKE IN THE WEST INDIES</h2>
+
+    <h4 class="sc">(From At Last.)</h4>
+
+    <h3><span class="sc">By</span> C. KINGSLEY.</h3>
+    <hr class="short">
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/097.png"><img width="250"
+             src="images/097.png"
+             alt="COOLIE AND NEGRO."></a><br>
+        COOLIE AND NEGRO.
+    </div>
+
+    <p>The Pitch Lake, like most other things, owes its appearance
+    on the surface to no convulsion or vagary at all, but to a most
+    slow, orderly, and respectable process of nature, by which
+    buried vegetable matter, which would have become peat, and
+    finally brown coal, in a temperate climate, becomes, under the
+    hot tropic soil, asphalt and oil, continually oozing up beneath
+    the pressure of the strata above it . . . .</p>
+    <hr>
+
+    <p>As we neared the shore, we perceived that the beach was
+    black with pitch; and the breeze being off the land, the
+    asphalt smell (not unpleasant) came off to welcome us. We rowed
+    in, and saw in front of a little row of wooden houses a tall
+    mulatto, in blue policeman's dress, gesticulating and shouting
+    to us. He was <span class="pagenum"><a id="page98"></a>[pg 98]</span> the ward policeman, and I
+       found him (as I did all the colored police) able and
+       courteous, shrewd and trusty. These police are excellent
+       specimens of what can be made of the negro, or half-negro,
+       if he be but first drilled, and then given a responsibility
+       which calls out his self-respect. He was warning our crew
+       not to run aground on one or other of the pitch reefs, which
+       here take the place of rocks. A large one, a hundred yards
+       off on the left, has been almost all dug away, and carried
+       to New York or to Paris to make asphalt-pavement.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/098.png"><img width="300"
+             src="images/098.png"
+             alt="THE POLICE STATION."></a><br>
+        THE POLICE STATION.
+    </div>
+
+    <p>The boat was run ashore, under his directions, on a spit of
+    sand between the pitch; and when she ceased bumping up and down
+    in the muddy surf, we scrambled out into a world exactly the
+    hue of its inhabitants of every shade, from jet black to
+    copper-brown. The pebbles on the shore were pitch. A tide-pool
+    close by was enclosed in pitch; a four-eyes was swimming about
+    in it, staring up at us; and when we hunted him, tried to
+    escape, not by diving, but by jumping on shore on the pitch,
+    and scrambling off between our legs. While the policeman, after
+    profoundest courtesies, was gone to get a mule-cart to take us
+    up to the lake, and planks <span class="pagenum"><a name=
+    "page99"
+       id="page99"></a>[pg 99]</span> to bridge its water channels,
+       we took a look round at this oddest of corners of the
+       earth.</p>
+
+    <p>In front of us was the unit of civilization,&mdash;the
+    police-station, wooden, on wooden stilts (as all well-built
+    houses are here), to insure a draught of air beneath them. We
+    were, of course, asked to come in and sit down, but preferred
+    looking about, under our umbrellas; for the heat was intense.
+    The soil is half pitch, half brown earth, among which the pitch
+    sweals in and out as tallow sweals from a candle. It is always
+    in slow motion under the heat of the tropic sun; and no wonder
+    if some of the cottages have sunk right and left in such a
+    treacherous foundation. A stone or brick house could not stand
+    here; but wood and palm-thatch are both light and tough enough
+    to be safe, let the ground give way as it will.</p>
+
+    <p>The soil, however, is very rich. The pitch certainly does
+    not injure vegetation, though plants will not grow actually in
+    it. The first plants which caught our eyes were pine-apples,
+    for which La Brea is famous. The heat of the soil, as well as
+    the air, brings them to special perfection. They grow about
+    anywhere, unprotected by hedge or fence; for the negroes here
+    seem honest enough, at least toward each other; and at the
+    corner of the house was a bush worth looking at, for we had
+    heard of it for many a year. It bore prickly, heart-shaped pods
+    an inch long, filled with seeds coated with a red waxy
+    pulp.</p>
+
+    <p>This was a famous plant&mdash;<i>Bixa orellana Roucou</i>;
+    and that pulp was the well-known annotto dye of commerce. In
+    England and Holland it is used merely, I believe, to color
+    cheeses, but in the Spanish Main to <span class=
+    "pagenum"><a id="page100"></a>[pg 100]</span> color human beings. The
+       Indian of the Orinoco prefers paint to clothes; and when he
+       has "roucoued" himself from head to foot, considers himself
+       in full dress, whether for war or dancing. Doubtless he
+       knows his own business best from long experience. Indeed, as
+       we stood broiling on the shore, we began somewhat to regret
+       that European manners and customs prevented our adopting the
+       Guaraon and Arrawak fashion.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/100.png"><img width="500"
+             src="images/100.png"
+             alt="THE MULE-CART."></a><br>
+        THE MULE-CART.
+    </div>
+
+    <p>The mule-cart arrived; the lady of the party was put into it
+    on a chair, and slowly bumped and rattled past the corner of
+    Dundonald Street&mdash;so named after the old sea-hero, who
+    was, in his life-time, full of projects for utilizing this same
+    pitch&mdash;and up in pitch road, with a pitch gutter on each
+    side.</p>
+
+    <p>The pitch in the road has been, most of it, laid down by
+    hand, and is slowly working down the slight incline, leaving
+    pools and ruts full of water, often invisible, because covered
+    with a film of brown pitch-dust, and so letting in the unwary
+    walker over his shoes. The <span class="pagenum"><a name=
+    "page101"
+       id="page101"></a>[pg 101]</span> pitch in the gutter-bank is
+       in its native place, and as it spues slowly out of the soil
+       into the ditch in odd wreaths and lumps, we could watch, in
+       little, the process which has produced the whole
+       deposit&mdash;probably the whole lake itself.</p>
+
+    <p>A bullock-cart, laden with pitch, came jolting down past us,
+    and we observed that the lumps, when the fracture is fresh,
+    have all a drawn out look; that the very air bubbles in them,
+    which are often very numerous, are all drawn out likewise, long
+    and oval, like the air-bubbles in some ductile lavas.</p>
+
+    <p>On our left, as we went on, the bush was low, all of yellow
+    cassia and white Hibiscus, and tangled with lovely
+    convolvulus-like creepers, Ipomoea and Echites, with white,
+    purple or yellow flowers. On the right were negro huts and
+    gardens, fewer and fewer as we went on,&mdash;all rich with
+    fruit trees, especially with oranges, hung with fruit of every
+    hue; and beneath them, of course, the pine-apples of La Brea.
+    Everywhere along the road grew, seemingly wild here, that
+    pretty low tree, Cashew, with rounded yellow-veined leaves and
+    little green flowers, followed by a quaint pink and red-striped
+    pear, from which hangs, at the larger and lower end, a
+    kidney-shaped bean, which bold folk eat when roasted; but woe
+    to those who try it when raw; for the acrid oil blisters the
+    lips, and even while the beans are roasting the fumes of the
+    oil will blister the cook's face if she holds it too near the
+    fire.</p>
+
+    <p>As we went onward up the gentle slope (the rise is one
+    hundred and thirty-eight feet in rather more than a mile), the
+    ground became more and more full of pitch, <span class=
+    "pagenum"><a id="page102"></a>[pg 102]</span> and the vegetation poorer
+       and more rushy, till it resembled, on the whole, that of an
+       English fen. An Ipomoea or two, and a scarlet flowered dwarf
+       Heliconia, kept up the tropic type, as does a stiff brittle
+       fern about two feet high. We picked the weeds, which looked
+       like English mint or basil, and found that most of them had
+       three longitudinal nerves in each leaf, and were really
+       Melastomas, though dwarfed into a far meaner habit than that
+       of the noble forms we saw at Chaguanas, and again on the
+       other side of the lake. On the right, too, in a hollow, was
+       a whole wood of Groogroo palms, gray stemmed, gray leaved,
+       and here and there a patch of white or black Roseau rose
+       gracefully eight or ten feet high among the reeds.</p>
+
+    <p>The plateau of pitch now widened out, and the whole ground
+    looked like an asphalt pavement, half overgrown with
+    marsh-loving weeds, whose roots feed in the sloppy water which
+    overlies the pitch. But, as yet, there was no sign of the lake.
+    The incline, though gentle, shuts off the view of what is
+    beyond. This last lip of the lake has surely overflowed, and is
+    overflowing still, though very slowly. Its furrows all curve
+    downward; and it is, in fact, as one of our party said, "a
+    black glacier." The pitch, expanding under the burning sun of
+    day, must needs expand most toward the line of least
+    resistance&mdash;that is, downhill; and when it contracts again
+    under the coolness of night, it contracts, surely, from the
+    same cause, more downhill than uphill; and so each particle
+    never returns to the spot whence it started, but rather drags
+    the particles above it downward toward itself. At least, so it
+    seemed to us. Thus may be explained the common mistake which is
+    noticed <span class="pagenum"><a id="page103"></a>[pg 103]</span> by Messrs. Wall and Sawkins
+       in their admirable description of the lake.</p>
+
+    <p>"All previous descriptions refer the bituminous matter
+    scattered over the La Brea district, and especially that
+    between the village and the lake, to streams which have issued
+    at some former epoch from the lake, and extended into the sea.
+    This supposition is totally incorrect, as solidification would
+    probably have ensued before it had proceeded one-tenth of the
+    distance; and such of the asphalt as has undoubtedly escaped
+    from the lake has not advanced more than a few yards, and
+    always presents the curved surfaces already described, and
+    never appears as an extended sheet."</p>
+
+    <p>Agreeing with this statement as a whole, I nevertheless
+    cannot but think it probable that a great deal of the asphalt,
+    whether it be in large masses or in scattered veins, may be
+    moving very slowly down hill, from the lake to the sea, by the
+    process of expansion by day and contraction by night, and may
+    be likened to a caterpillar, or rather caterpillars
+    innumerable, progressing by expanding and contracting their
+    rings, having strength enough to crawl down hill, but not
+    strength enough to back up hill again.</p>
+
+    <p>At last we surmounted the last rise, and before us lay the
+    famous lake&mdash;not at the bottom of a depression, as we
+    expected, but at the top of a rise, whence the ground slopes
+    away from it on two sides, and rises from it very slightly on
+    the two others. The black pool glared and glittered in the sun.
+    A group of islands, some twenty yards wide, were scattered
+    about the middle of it. Beyond it rose a double forest of
+    Moriche fan-palms; and to the right of them high
+          <span class="pagenum"><a id="page104"></a>[pg 104]</span> wood with giant Mombins and
+       undergrowth of Cocorite&mdash;a paradise on the other side
+       of the Stygian pool.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/104.png"><img width="500"
+             src="images/104.png"
+             alt="THE PITCH LAKE."></a><br>
+        THE PITCH LAKE.
+    </div>
+
+    <p>We walked, with some misgivings, on to the asphalt, and
+    found it perfectly hard. In a few steps we were stopped by a
+    channel of clear water, with tiny fish and water-beetles in it;
+    and, looking round, saw that the whole lake was intersected
+    with channels, so unlike anything which can be seen elsewhere
+    that it is not easy to describe them.</p>
+
+    <p>Conceive a crowd of mushrooms, of all shapes, from ten to
+    fifty feet across, close together side by side, their tops
+    being kept at exactly the same level, their rounded rims
+    squeezed tight against each other; then conceive water poured
+    on them so as to fill the parting seams, and in the wet season,
+    during which we visited it, to overflow the tops somewhat. Thus
+    would each mushroom represent, tolerably well, one of
+    <span class="pagenum"><a id="page105"></a>[pg 105]</span> the innumerable flat
+       asphalt bosses, which seem to have sprung up each from a
+       separate centre, while the parting seams would be of much
+       the same shape as those in the asphalt, broad and shallow
+       atop, and rolling downward in a smooth curve, till they are
+       at bottom mere cracks from two to ten feet deep. Whether
+       these cracks actually close up below, and the two contiguous
+       masses of pitch become one, cannot be seen. As far as the
+       eye goes down, they are two, though pressed close to each
+       other. Messrs. Wall and Sawkins explain the odd fact clearly
+       and simply. The oil, they say, which the asphalt contains
+       when it rises first, evaporates in the sun, of course most
+       on the outside of the heap, leaving a thorough coat of
+       asphalt, which has, generally, no power to unite with the
+       corresponding coat of the next mass. Meanwhile Mr. Manross,
+       an American gentleman, who has written a very clever and
+       interesting account of the lake, seems to have been so far
+       deceived by the curved and squeezed edges of these masses
+       that he attributes to each of them a revolving motion, and
+       supposes that the material is continually passing from the
+       centre to the edges, when it "rolls under," and rises again
+       in the middle. Certainly the strange stuff looks, at the
+       first glance, as if it were behaving in this way; and
+       certainly, also, his theory would explain the appearance of
+       sticks and logs in the pitch. But Messrs. Wall and Sawkins
+       say that they have observed no such motion: nor did we; and
+       I agree with them, that it is not very obvious to what
+       force, or what influence, it could be attributable. We must,
+       therefore, seek some other way of accounting for the
+       sticks&mdash;which utterly <span class="pagenum"><a name=
+       "page106"
+       id="page106"></a>[pg 106]</span> puzzled us, and which Mr.
+       Manross well describes as "numerous pieces of wood, which,
+       being involved in the pitch, are constantly coming to the
+       surface. They are often several feet in length, and five or
+       six inches in diameter. On reaching the surface they
+       generally assume an upright position, one end being detained
+       in the pitch, while the other is elevated by the lifting of
+       the middle. They may be seen at frequent intervals over the
+       lake, standing up to the height of two or even three feet.
+       They look like stumps of trees protruding through the pitch;
+       but their parvenu character is curiously betrayed by a
+       ragged cap of pitch which invariably covers the top, and
+       hangs down like hounds' ears on either side."</p>
+
+    <p>Whence do they come? Have they been blown on to the lake, or
+    left behind by man? or are they fossil trees, integral parts of
+    the vegetable stratum below which is continually rolling
+    upward? or are they of both kinds? I do not know. Only this is
+    certain, as Messrs. Wall and Sawkins have pointed out, that not
+    only "the purer varieties of asphalt, such as approach or are
+    identical with asphalt glance, have been observed" (though not,
+    I think, in the lake itself) "in isolated masses, where there
+    was little doubt of their proceeding from ligneous substances
+    of larger dimensions, such as roots and pieces of trunks and
+    branches," but, moreover, that "it is also necessary to admit a
+    species of conversion by contact, since pieces of wood included
+    accidentally in the asphalt, for example, by dropping from
+    overhanging vegetation, are often found partially transformed
+    into the material." This is a statement which we verified again
+    and again, as we <span class="pagenum"><a id="page107"></a>[pg 107]</span> did the one which follows,
+       namely, that the hollow bubbles which abound on the surface
+       of the pitch "generally contain traces of the lighter
+       portion of vegetation," and "are manifestly derived from
+       leaves, etc., which are blown about the lake by the wind,
+       and are covered with asphalt, and, as they become asphalt
+       themselves, give off gases which form bubbles round
+       them."</p>
+
+    <p>But how is it that those logs stand up out of the asphalt,
+    with asphalt caps and hounds' ears (as Mr. Manross well phrases
+    it) on the tops of them?</p>
+
+    <p>We pushed on across the lake, over the planks which the
+    negroes laid down from island to island. Some, meanwhile,
+    preferred a steeple-chase with water-jumps, after the fashion
+    of the midshipmen on a certain second visit to the lake. How
+    the negroes grinned delight and surprise at the vagaries of
+    English lads&mdash;a species of animal altogether new to them;
+    and how they grinned still more when certain staid and portly
+    dignitaries caught the infection, and proved by more than one
+    good leap that they too had been English
+    school-boys&mdash;alas! long, long ago.</p>
+
+    <p>So, whether by bridging, leaping, or wading, we arrived at
+    the little islands, and found them covered with a thick, low
+    scrub; deep sedge, and among them Pinguins, like huge
+    pine-apples without the apple; gray wild-pines, parasites on
+    Matapalos, which, of course, have established themselves, like
+    robbers and vagrants as they are, everywhere; a true holly,
+    with box-like leaves; and a rare cocoa-plum, very like the
+    holly in habit, which seems to be all but confined to these
+    little patches of red earth, afloat on the pitch. Out of the
+    <span class="pagenum"><a id="page108"></a>[pg 108]</span> scrub, when we were there,
+       flew off two or three night-jars, very like our English
+       species, save that they had white in the wings; and on the
+       second visit one of the midshipmen, true to the English
+       boy's bird's-nesting instinct, found one of their eggs,
+       white-spotted, in a grass nest.</p>
+
+    <p>Passing these little islands, which are said (I know not how
+    truly) to change their places and number, we came to the very
+    fountains of Styx, to that part of the lake where the asphalt
+    is still oozing up.</p>
+
+    <p>As the wind set toward us, we soon became aware of an evil
+    smell&mdash;petroleum and sulphureted hydrogen at
+    once&mdash;which gave some of us a headache. The pitch here is
+    yellow and white with sulphur foam; so are the water-channels;
+    and out of both water and pitch innumerable bubbles of gas
+    arise, loathsome to the smell. We became aware that the pitch
+    was soft under our feet. We left the impression of our boots;
+    and if we had stood still awhile, we should soon have been
+    ankle-deep. No doubt there are spots where, if a man stayed
+    long enough, he would be slowly and horribly engulfed. "But,"
+    as Mr. Manross says truly, "in no place is it possible to form
+    those bowl-like depressions round the observer described by
+    former travellers." What we did see is that the fresh pitch
+    oozes out at the lines of least resistance, namely, in the
+    channels between the older and more hardened masses, usually at
+    the upper ends of them, so that one may stand on pitch
+    comparatively hard, and put one's hand into pitch quite liquid,
+    which is flowing softly out, like some ugly fungoid growth,
+    such as may be seen in old wine-cellars, into the water. One
+    such pitch-fungus had grown <span class="pagenum"><a name=
+    "page109"
+       id="page109"></a>[pg 109]</span> several yards in length in
+       the three weeks between our first and second visit; and on
+       another, some of our party performed exactly the same feat
+       as Mr. Manross.</p>
+
+    <p>"In one of the star-shaped pools of water, some five feet
+    deep, a column of pitch had been forced perpendicularly up from
+    the bottom. On reaching the surface of the water it had formed
+    a sort of centre-table, about four feet in diameter, but
+    without touching the sides of the pool. The stem was about a
+    foot in diameter. I leaped out on this table, and found that it
+    not only sustained my weight, but that the elasticity of the
+    stem enabled me to rock it from side to side. Pieces torn from
+    the edges of this table sank readily, showing that it had been
+    raised by pressure, and not by its buoyancy."</p>
+
+    <p>True, though strange; but stranger still did it seem to us
+    when we did at last what the negroes asked us, and dipped our
+    hands into the liquid pitch, to find that it did not soil the
+    fingers. The old proverb that one cannot touch pitch without
+    being defiled happily does not stand true here, or the place
+    would be intolerably loathsome. It can be scraped up, moulded
+    into any shape you will, wound in a string (as was done by one
+    of the midshipmen) round a stick, and carried off; but nothing
+    is left on the hand save clean gray mud and water. It may be
+    kneaded for an hour before the mud be sufficiently driven out
+    of it to make it sticky. This very abundance of earthy matter
+    it is which, while it keeps the pitch from soiling, makes it
+    far less valuable than it would be were it pure.</p>
+
+    <p>It is easy to understand whence this earthy matter (twenty
+    or thirty per cent) comes. Throughout the <span class=
+    "pagenum"><a id="page110"></a>[pg 110]</span> neighborhood the ground is
+       full, to the depth of hundreds of feet, of coaly and
+       asphaltic matter. Layers of sandstone or of shale containing
+       this decayed vegetable alternate with layers which contain
+       none; and if, as seems probable, the coaly matter is
+       continually changing into asphalt and oil, and then working
+       its way upward through every crack and pore, to escape from
+       the enormous pressure of the superincumbent soil, it must
+       needs carry up with it innumerable particles of the soils
+       through which it passes.</p>
+
+    <p>In five minutes we had seen, handled, and smelt enough to
+    satisfy us with this very odd and very nasty vagary of tropic
+    nature; and as we did not wish to become faint and ill between
+    the sulphureted hydrogen and the blaze of the sun reflected off
+    the hot black pitch, we hurried on over the water-furrows, and
+    through the sedge-beds to the farther shore&mdash;to find
+    ourselves, in a single step, out of an Inferno into a
+    Paradise.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/110.png"><img width="500"
+             src="images/110.png"
+             alt="Pitch pool."></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="page111"></a>[pg 111]</span>
+
+    <h2>A STALAGMITE CAVE</h2>
+
+    <h4 class="sc">(From the Voyage of the Challenger.)</h4>
+
+    <h3><span class="sc">By</span> SIR C. WYVILLE THOMSON, KT.,
+    LL.D., ETC.</h3>
+    <hr class="short">
+
+    <div class="figleft"
+         style="width:150px">
+        <a href="images/111.png"><img width="150"
+             src="images/111.png"
+             alt="Painter's Vale cave"></a>
+    </div>
+
+    <p>I think the Painter's Vale cave is the prettiest of the
+    whole. The opening is not very large. It is an arch over a
+    great mass of débris forming a steep slope into the cave, as if
+    part of the roof of the vault had suddenly fallen in. At the
+    foot of the bank of débris one can barely see in the dim light
+    the deep clear water lying perfectly still and reflecting the
+    roof and margin like a mirror. We clambered down the slope, and
+    as the eye became more accustomed to the obscurity the lake
+    stretched further back. There was a crazy little punt moored to
+    the shore, and after lighting candles Captain Nares rowed the
+    Governor back into the darkness, the candles throwing a dim
+    light for a <span class="pagenum"><a id="page112"></a>[pg 112]</span> time&mdash;while the voices
+       became more hollow and distant&mdash;upon the surface of the
+       water and the vault of stalactite, and finally passing back
+       as mere specks into the silence.</p><br>
+
+    <div class="figright"
+         style="width:225px;">
+        <a href="images/112.png"><img width="225"
+             src="images/112.png"
+             alt="A GUIDE."></a><br>
+        A GUIDE.
+    </div>
+
+    <p>After landing the Governor on the opposite side, Captain
+    Nares returned for me, and we rowed round the weird little
+    lake. It was certainly very curious and beautiful; evidently a
+    huge cavity out of which the calcareous sand had been washed or
+    dissolved, and whose walls, still to a certain extent
+    permeable, had been hardened and petrified by the constant
+    percolation of water charged with carbonate of lime. From the
+    roof innumerable stalactites, perfectly white, often several
+    yards long and coming down to the delicacy of knitting-needles,
+    hung in clusters; and wherever there was any continuous crack
+    in the roof or wall, a graceful, soft-looking curtain of white
+    stalactite fell, and often ended, much to our surprise. Deep in
+    the water Stalagmites also rose up in pinnacles and fringes
+    through the water, which was so exquisitely still and clear
+    that it was something difficult to tell where the solid marble
+    tracery ended, and its reflected image began. In this cave,
+    which is a considerable distance from the sea, there is a
+    slight change of level with the tide sufficient
+          <span class="pagenum"><a id="page113"></a>[pg 113]</span> to keep the water perfectly
+       pure. The mouth of the cave is overgrown with foliage, and
+       every tree is draped and festooned with the fragrant
+       <i>Jasminum gracile</i>, mingled not unfrequently with the
+       "poison ivy" (<i>Rhus toxicodendron</i>). The Bermudians,
+       especially the dark people, have a most exaggerated horror
+       of this bush. They imagine that if one touch it or rub
+       against it he becomes feverish, and is covered with an
+       eruption. This is no doubt entirely mythical. The plant is
+       very poisonous, but the perfume of the flower is rather
+       agreeable, and we constantly plucked and smelt it without
+       its producing any unpleasant effect. The tide was with us
+       when we regained the Flats Bridge, and the galley shot down
+       the rapid like an arrow, the beds of scarlet sponges and the
+       great lazy trepangs showing perfectly clearly on the bottom
+       at a fathom depth.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/113.png"><img width="300"
+             src="images/113.png"
+             alt=
+           "FIG. 1. CALCAREOUS CONCRETION SIMULATING A FOSSIL PALM-STEM, BOAZ ISLAND, BERMUDAS."></a>
+
+        <p>FIG. 1. CALCAREOUS CONCRETION SIMULATING A FOSSIL
+        PALM-STEM, BOAZ ISLAND, BERMUDAS.</p>
+    </div>
+
+    <p>Every here and there throughout the islands there are groups
+    of bodies of very peculiar form projecting from the surface of
+    the limestone where it has been weathered. These have usually
+    been regarded as fossil palmetto stumps, the roots of trees
+    which have been overwhelmed with sand and whose organic matter
+    has been entirely removed and replaced by carbonate of lime.
+    Fig. 1 represents one of the most characteristic
+          <span class="pagenum"><a id="page114"></a>[pg 114]</span> of these from a group on
+       the side of the road in Boaz Island. It is a cylinder a foot
+       in diameter and six inches or so high; the upper surface
+       forms a shallow depression an inch deep surrounded by a
+       raised border; the bottom of the cup is even, and pitted
+       over with small depressions like the marks of rain-drops on
+       sand; the walls of the cylinder seem to end a few inches
+       below the surface of the limestone in a rounded boss, and
+       all over this there are round markings or little cylindrical
+       projections like the origins of rootlets. The object
+       certainly appears to agree even in every detail with a
+       fossil palm-root, and as the palmetto is abundant on the
+       islands and is constantly liable to be destroyed by and
+       ultimately enveloped in a mass of moving sand, it seemed
+       almost unreasonable to question its being one. Still
+       something about the look of these things made me doubt, with
+       General Nelson, whether they were fossil palms, or indeed
+       whether they were of organic origin at all; and after
+       carefully examining and <span class="pagenum"><a name=
+       "page115"
+       id="page115"></a>[pg 115]</span> pondering over several
+       groups of them, at Boaz Island, on the shore at Mount
+       Langton, and elsewhere, I finally came to the conclusion
+       that they were not fossils, but something totally
+       different.</p>
+
+    <div class="figcenter"
+         style="width:300px;">
+        <a href="images/114-1.png"><img width="300"
+             src="images/114-1.png"
+             alt=
+           "FIG. 2. CALCAREOUS CONCRETION IN AEOLIAN LIMESTONE, BERMUDAS."></a>
+
+        <p>FIG. 2. CALCAREOUS CONCRETION IN AEOLIAN LIMESTONE,
+        BERMUDAS.</p>
+    </div>
+
+    <div class="figcenter"
+         style="width:350px;">
+        <a href="images/114-2.png"><img width="350"
+             src="images/114-2.png"
+             alt=
+           "FIG. 3. CALCAREOUS CONCRETION IN AEOLIAN LIMESTONE, BERMUDAS."></a>
+
+        <p>FIG. 3. CALCAREOUS CONCRETION IN AEOLIAN LIMESTONE,
+        BERMUDAS.</p>
+    </div>
+
+    <div class="figcenter"
+         style="width:350px;">
+        <a href="images/115-1.png"><img width="350"
+             src="images/115-1.png"
+             alt="FIG. 4. CALCAREOUS CONCRETION, BERMUDAS."></a>
+
+        <p>FIG. 4. CALCAREOUS CONCRETION, BERMUDAS.</p>
+    </div>
+
+    <div class="figcenter"
+         style="width:275px;">
+        <a href="images/115-2.png"><img width="275"
+             src="images/115-2.png"
+             alt=
+           "FIG. 5. CALCAREOUS CONCRETION IN AEOLIAN LIMESTONE, BERMUDAS."></a>
+
+        <p>FIG. 5. CALCAREOUS CONCRETION IN AEOLIAN LIMESTONE,
+        BERMUDAS.</p>
+    </div>
+
+    <p>The form given in Fig. 1 is the most characteristic, and
+    probably by far the most common; but very frequently one of a
+    group of these, one which is evidently essentially the same as
+    the rest and formed in the same way, has an oval or an
+    irregular shape (Figs. 2, 3, and 4). In these we have the same
+    raised border, the same scars on the outside, the same origins
+    of root-like fibres, and the same pitting of the bottom of the
+    shallow cup; but their form precludes the possibility of their
+    being tree-roots. In some cases (Fig. 5), a group of so-called
+    "palm-stems" is inclosed in a space surrounded by a ridge, and
+    on examining it closely this outer ridge is found to show the
+    same leaf-scars and traces of rootlets as the "palm-stems"
+    themselves. In some cases very irregular honey-combed figures
+    are produced which the examination <span class=
+    "pagenum"><a id="page116"></a>[pg 116]</span> of a long series of
+       intermediate forms shows to belong to the same category
+       (Fig. 6).</p>
+
+    <div class="figleft"
+         style="width:400px;">
+        <a href="images/116.png"><img width="400"
+             src="images/116.png"
+             alt="FIG. 6. CONCRETIONS IN AEOLIAN ROCKS,"></a>
+
+        <p>FIG. 6. CONCRETIONS IN AEOLIAN ROCKS, BERMUDAS.</p>
+    </div>
+
+    <p>In the caves in the limestone, owing to a thread of water
+    having found its way in a particular direction through the
+    porous stone of the roof, a drop falls age after age on one
+    spot on the cave-floor, accurately directed by the stalactite
+    which it is all the time creating. The water contains a certain
+    proportion of carbonate of lime, which is deposited as
+    stalagmite as the water evaporates, and thus a ring-like crust
+    is produced at a little distance from the spot where the drop
+    falls. When a ring is once formed, it limits the spread of the
+    drop, and determines the position of the wall bounding the
+    little pool made by the drop. The floor of the cave gradually
+    rises by the accumulation of sand and travertine, and with it
+    rise the walls and floor of the cup by the deposit of
+    successive layers of stalagmite produced by the drop
+    percolating into the limestone of the floor which hardens it
+    still further, but in this peculiar symmetrical way. From the
+    floor and sides of the cup the water oozes into the softer
+    limestone around and beneath; but, as in all these limestones,
+    it does not ooze indiscriminately, but follows certain more
+    free paths. These become soon lined and finally blocked with
+    <span class="pagenum"><a id="page117"></a>[pg 117]</span> stalagmite, and it is these
+       tubes and threads of stalagmite which afterwards in the
+       pseudo-fossil represent the diverging rootlets.</p>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/139.jpg"><img width="400"
+             src="images/139sm.jpg"
+             alt="A STALAGMITE CAVE."></a><br>
+        A STALAGMITE CAVE.
+    </div>
+
+    <p>Sometimes when two or more drops fall from stalactites close
+    to one another the cups coalesce (Figs. 2, 3, and 4); sometimes
+    one drop or two is more frequent than the other, and then we
+    have the form shown in Figs. 3 and 4; sometimes many drops
+    irregularly scattered form a large pool with its raised border,
+    and a few drops more frequent and more constant than the rest
+    grow their "palmetto stems" within its limit (Fig. 5); and
+    sometimes a number of drops near one another make a curious
+    regular pattern, with the partitions between the recesses quite
+    straight (Fig. 6).</p>
+
+    <p>I have already referred to the rapid denudation which is
+    going on in these islands, and to the extent to which they have
+    been denuded within comparatively recent times. The floors of
+    caves, from their being cemented into a nearly homogeneous mass
+    by stalagmitic matter, are much harder than the ordinary porous
+    blown limestone; and it seems that in many cases, after the
+    rocks forming the walls and roof have been removed,
+    disintegration has been at all events temporarily arrested by
+    the floor. Where there is a flat surface of rock exposed
+    anywhere on the island, it very generally bears traces of
+    having been at one time the floor of a cave; and as the
+    weather-wearing of the surface goes on, the old concretionary
+    structures are gradually brought out again, the parts specially
+    hardened by a localized slow infiltration of lime resist
+    integration longest and project above the general surface.
+    Often <span class="pagenum"><a id="page118"></a>[pg 118]</span> a surface of weathered rock
+       is so studded with these symmetrical concretions, that it is
+       hard to believe that one is not looking at the calcified
+       stumps of a close-growing grove of palms.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/118.png"><img width="500"
+             src="images/118.png"
+             alt="Stlagmite cave."></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="page119"></a>[pg 119]</span>
+
+    <h2>THE BIG TREES OF CALIFORNIA</h2>
+
+    <h4 class="sc">(From Studies Scientific and Social.)</h4>
+
+    <h3><span class="sc">By</span> ALFRED RUSSEL WALLACE.</h3>
+    <hr class="short">
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/119.png"><img width="200"
+             src="images/119.png"
+             alt="Big trees."></a>
+    </div>
+
+    <p>In the popular accounts of these trees it is usual to dwell
+    only on the dimensions of the very largest known specimens, and
+    sometimes even to exaggerate these. Even the smaller full-grown
+    trees, however, are of grand dimensions, varying from fourteen
+    to eighteen feet in diameter, at six feet above the ground, and
+    keeping nearly the same thickness for perhaps a hundred feet.
+    In the south Calaveras grove, where there are more than a
+    thousand trees, the exquisite beauty of the trunks is well
+    displayed by the numerous specimens in perfect health and
+    vigor. The bark of these trees, seen at a little distance, is
+    of a bright orange brown tint, delicately mottled with darker
+    shades, and with a curious silky or plush-like gloss, which
+    gives them a richness of color far beyond that of any other
+    conifer. The tree which was cut down soon after the first
+    discovery of the species, the <span class="pagenum"><a name=
+    "page120"
+       id="page120"></a>[pg 120]</span> stump of which is now
+       covered with a pavilion, is twenty-five feet in diameter at
+       six feet above the ground, but this is without the thick
+       bark, which would bring it to twenty-seven feet when alive.
+       A considerable portion of this tree still lies where it
+       fell, and at one hundred and thirty feet from the base I
+       found it to be still twelve and a half feet in diameter (or
+       fourteen feet with the bark), while at the extremity of the
+       last piece remaining, two hundred and fifteen feet from its
+       base, it is six feet in diameter, or at least seven feet
+       with the bark. The height of this tree when it was cut down
+       is not recorded, but as one of the living trees is more than
+       three hundred and sixty feet high, it is probable that this
+       giant was not much short of four hundred
+          feet.</p><br>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/120.png"><img width="300"
+             src="images/120.png"
+             alt="THE 'MOTHER OF THE FOREST.'"></a><br>
+        THE "MOTHER OF THE FOREST."
+    </div>
+
+    <p>In the accompanying picture the dead tree in the centre is
+    that from which the bark was stripped, which was erected in the
+    Crystal Palace and unfortunately destroyed by fire. It is
+    called the "Mother of the <span class="pagenum"><a name=
+    "page121"
+       id="page121"></a>[pg 121]</span> Forest." The two trees
+       nearer the foreground are healthy, medium-sized trees, about
+       fifteen feet diameter at six feet above the ground.</p>
+
+    <p>The huge decayed trunk called "Father of the Forest," which
+    has fallen perhaps a century or more, exhibits the grandest
+    dimensions of any known tree. By measuring its remains, and
+    allowing for the probable thickness of the bark, it seems to
+    have been about thirty-five feet diameter near the ground, at
+    ninety feet up fifteen feet, and even at a height of two
+    hundred and seventy feet, it was nine feet in diameter. It is
+    within the hollow trunk of this tree that a man on horse-back
+    can ride&mdash;both man and horse being rather small; but the
+    dimensions undoubtedly show that it was considerably larger
+    than the "Pavilion tree," and that it carried its huge
+    dimensions to a greater altitude; and although this does not
+    prove it to have been much taller, yet it was in all
+    probability more than four hundred feet in
+          height.</p><br>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/122.png"><img width="400"
+             src="images/122.png"
+             alt="Tunnel through tree."></a>
+    </div>
+
+    <p>Very absurd statements are made to visitors as to the
+    antiquity of these trees, three or four thousand years being
+    usually given as their age. This is founded on the fact that
+    while many of the large Sequoias are greatly damaged by fire,
+    the large pines and firs around them are quite uninjured. As
+    many of these pines are assumed to be near a thousand years
+    old, the epoch of the "great fire" is supposed to be earlier
+    still, and as the Sequoias have not outgrown the fire-scars in
+    all that time, they are supposed to have then arrived at their
+    full growth. But the simple explanation of these trees alone
+    having suffered so much from fire is, that their bark is
+    unusually thick, dry, soft, and fibrous, <span class=
+    "pagenum"><a id="page122"></a>[pg 122]</span> and it thus catches fire
+       more easily and burns more readily and for a longer time
+       than that of the other coniferæ. Forest fires occur
+       continually, and the visible damage done to these trees has
+       probably all occurred in the present century. Professor C.B.
+       Bradley, of the University of California, has carefully
+       counted the rings of annual growth on the stump of the
+       "Pavilion tree," and found them to be twelve hundred and
+       forty; and after considering all that has been alleged as to
+       the uncertainty of this mode of estimating <span class=
+       "pagenum"><a id="page123"></a>[pg 123]</span> the age of a tree, he
+       believes that in the climate of California, in the zone of
+       altitude where these trees grow, the seasons of growth and
+       repose are so strongly marked that the number of annual
+       rings gives an accurate result.</p>
+
+    <p>Other points that have been studied by Professor Bradley
+    are, the reason why there are so few young trees in the groves,
+    and what is the cause of the destruction of the old trees. To
+    take the last point first, these noble trees seem to be
+    singularly free from disease or from decay due to old age. All
+    the trees that have been cut down are solid to the heart, and
+    none of the standing trees show any indications of natural
+    decay. The only apparent cause for their overthrow is the wind,
+    and by noting the direction of a large number of fallen trees
+    it is found that the great majority of them lie more or less
+    towards the south. This is not the direction of the prevalent
+    winds, but many of the tallest trees lean towards the south,
+    owing to the increased growth of their topmost branches towards
+    the sun. They are then acted upon by violent gales, which
+    loosen their roots, and whatever the direction of the wind that
+    finally overthrows them, they fall in the direction of the
+    over-balancing top weight. The young trees grow spiry and
+    perfectly upright, but as soon as they overtop the surrounding
+    trees and get the full influence of the sun and wind, the
+    highest branches grow out laterally, killing those beneath
+    their shade, and thus a dome-shaped top is produced. Taking
+    into consideration the health and vigor of the largest trees,
+    it seems probable that, under favorable conditions of shelter
+    from violent winds, and from a number of trees
+          <span class="pagenum"><a id="page124"></a>[pg 124]</span> around them of nearly equal
+       height, big trees might be produced far surpassing in height
+       and bulk any that have yet been discovered. It is to be
+       hoped that if any such are found to exist in the extensive
+       groves of these trees to the south of those which are alone
+       accessible to tourists, the Californian Government will take
+       steps to reserve a considerable tract containing them, for
+       the instruction and delight of future generations.</p>
+
+    <p>The scarcity of young Sequoias strikes every visitor, the
+    fact being that they are only to be found in certain favored
+    spots. These are, either where the loose débris of leaves and
+    branches which covers the ground has been cleared away by fire,
+    or on the spots where trees have been uprooted. Here the young
+    trees grow in abundance, and serve to replace those that fall.
+    The explanation of this is, that during the long summer drought
+    the loose surface débris is so dried up that the roots of the
+    seedling Sequoias perish before they can penetrate the earth
+    beneath. They require to germinate on the soil itself, and this
+    they are enabled to do when the earth is turned up by the fall
+    of a tree, or where a fire has cleared off the débris. They
+    also flourish under the shade of the huge fallen trunks in
+    hollow places, where moisture is preserved throughout the
+    summer. Most of the other conifers of these forests, especially
+    the pines, have much larger seeds than the Sequoias, and the
+    store of nourishment in these more bulky seeds enables the
+    young plants to tide over the first summer's drought. It is
+    clear, therefore, that there are no indications of natural
+    decay in these forest giants. In every stage of their growth
+    they are vigorous <span class="pagenum"><a id="page125"></a>[pg 125]</span> and healthy, and they have
+       nothing to fear except from the destroying hand of man.</p>
+
+    <div class="figright"
+         style="width:350px;">
+        <a href="images/125.png"><img width="350"
+             src="images/125.png"
+             alt="REDWOOD TREE WITH TRIPLE TRUNK."></a><br>
+        REDWOOD TREE WITH TRIPLE TRUNK.
+    </div>
+
+    <p>Destruction from this cause is, however, rapidly diminishing
+    both the giant Sequoia and its near ally the noble redwood
+    (<i>Sequoia sempervirens</i>), a tree which is more beautiful
+    in foliage and in some other respects more remarkable than its
+    brother species, while there is reason to believe that under
+    favorable conditions it reaches an equally phenomenal size. It
+    once covered almost all the coast ranges of central and
+    northern California, but has been long since cleared away in
+    the vicinity of San Francisco, and greatly diminished
+    elsewhere. A grove is preserved for the benefit of tourists
+    near Santa Cruz, the largest tree being two hundred and
+    ninety-six feet high, twenty-nine feet diameter at the ground
+    and fifteen feet at six feet above it. One of these trees
+    having a triple trunk is here figured from a photograph. Much
+    larger trees, however, exist in the great forests of this tree
+    in the northern part of the State; but <span class=
+    "pagenum"><a id="page126"></a>[pg 126]</span> these are rapidly being
+       destroyed for the timber, which is so good and durable as to
+       be in great demand. Hence Californians have a saying that
+       the redwood is too good a tree to live. On the mountains a
+       few miles east of the Bay of San Francisco, there are a
+       number of patches of young redwoods, indicating where large
+       trees have been felled, it being a peculiarity of this tree
+       that it sends up vigorous young plants from the roots of old
+       ones immediately around the base. Hence in the forests these
+       trees often stand in groups arranged nearly in a circle,
+       thus marking out the size of the huge trunks of their
+       parents. It is from this quality that the tree has been
+       named <i>sempervirens</i>, or ever flourishing. Dr. Gibbons,
+       of Alameda, who has explored all the remains of the redwood
+       forests in the neighborhood of Oakland, kindly took me to
+       see the old burnt-out stump of the largest tree he had
+       discovered. It is situated about fifteen hundred feet above
+       the sea, and is thirty-four feet in diameter at the ground.
+       This is as large as the very largest specimens of the
+       <i>Sequoia gigantea</i>, but it may have spread out more at
+       the base and have been somewhat smaller above, though this
+       is not a special characteristic of the
+          species.</p><br>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/126.png"><img width="500"
+             src="images/126.png"
+             alt="Sequoias."></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="page127"></a>[pg 127]</span>
+
+    <h2>WHAT IS EVOLUTION?</h2>
+
+    <h4>(<span class="sc">From The Atlantic Monthly, March,
+    '93.</span>)</h4>
+
+    <h3><span class="sc">By</span> PROFESSOR E.S. HOLDEN.</h3>
+    <hr class="short">
+
+    <div class="figleft"
+         style="width:150px;">
+        <a href="images/127.png"><img width="150"
+             src="images/127.png"
+             alt="Oak tree."></a>
+    </div>
+
+    <p>I was once trying to tell a boy, a friend of mine, what the
+    scientific men mean by the long word <i>Evolution</i>, and to
+    give him some idea of the plan of the world. I wanted an
+    illustration of something that had grown&mdash;evolved,
+    developed&mdash;from small beginnings up through more and more
+    complicated forms, till it had reached some very complete form.
+    I could think of no better example than the railway by which we
+    were sitting. The trains were running over the very track where
+    a wagon-road had lately been, and before that a country
+    cart-track, and before that a bridle-path, and before that
+    again a mere trail for cattle. So I took the road for an
+    example, and tried to show my boy how it had grown from little
+    things by slow degrees according to laws; and if you like, I
+    will try to tell it again.</p>
+
+    <p>Just as one can go further and further back, and always find
+    a bird to be the parent of the egg, and an egg to be the parent
+    of that bird, so in the history of <span class=
+    "pagenum"><a id="page128"></a>[pg 128]</span> this road of ours; we may
+       go back and back into the past, always finding something
+       earlier, which is the cause of the something later. The
+       earth, the planets, and the sun were all a fiery mist long
+       ago. And in that mist, and in what came before it, we may
+       look for the origin of things as they are. But we must begin
+       somewhere. Let us begin with the landscape as we see it
+       now,&mdash;hills, valleys, streams, mountains,
+       grass,&mdash;but with only a single tree.</p>
+
+    <p>We will not try to say how the tree came there. At least, we
+    will not try just yet. When we are through with the story you
+    can say just as well as I can.</p>
+
+    <p>Suppose, then, a single oak-tree stood just on that hillside
+    thousands and thousands of years ago. Grass was growing
+    everywhere, and flowers, too. The seeds came with the winds.
+    Year after year the oak-tree bore its acorns, hundreds and
+    hundreds of them, and they fell on the grass beneath and rolled
+    down the smooth slopes, and sprouted as best they
+    could,&mdash;most of them uselessly so far as producing trees
+    were concerned,&mdash;but each one did its duty and furnished
+    its green sprout, and died if it found no nourishment.</p>
+
+    <p>All the hundreds of acorns rolled down the slopes, Not one
+    rolled up; and here was a <i>law</i>,&mdash;the law of
+    gravitation,&mdash;in full activity. There were scores of other
+    laws active, too; for evolution had gone a long way when we had
+    an earth fit to be lived on, and hills in their present shape,
+    and a tree bearing acorns that would reproduce their kind. But
+    ever since the fiery mist this simple law of gravitation has
+    been acting, binding the whole universe together, making a
+    relationship between each clod and every other clod, and
+    <span class="pagenum"><a id="page129"></a>[pg 129]</span> forcing every stone, every
+       acorn, and every rain-drop to move down and not up.</p>
+
+    <p>Just as this law operates,&mdash;continuously, silently,
+    inexorably,&mdash;so every other law makes itself felt in its
+    own sphere. Gravitation is simple. The law according to which
+    an acorn makes an oak&mdash;and not a pine-tree is complex. But
+    the laws of Nature are all alike, and if we understand the
+    simple ones, we can at least partly comprehend the more
+    complex. They are nothing but fixed habits on a large
+    scale.</p>
+
+    <p>So the acorns fell year by year and sprouted; and one out of
+    a thousand found good soil, and was not wasted, and made a
+    tree. And so all around (below) the tree with which we started
+    there grew a grove of oaks like it, in fact its children; and
+    finally the original trees died, but not without having left
+    successors.</p>
+
+    <p>First of all, the green hillside is smooth and untrodden.
+    There is nothing but grass and flowers, borne there by the
+    winds, which leave no track. There is no animal life even in
+    this secluded spot save the birds, and they too leave no track.
+    By and by there comes a hard winter, or a dearth of food, and a
+    pair of stray squirrels emigrate from their home in the valley
+    below; and the history of our hill and its woods begins. Mere
+    chance decides the choice of the particular oak-tree in which
+    the squirrels make their home. From the foot of this tree they
+    make excursions here and there for their store of winter
+    food,&mdash;acorns and the like,&mdash;and they leave little
+    paths on the hillside from tree to tree.</p>
+
+    <p>The best-marked paths run to the places where there are the
+    most acorns. A little later on there are more squirrels in the
+    colony,&mdash;the young of the parent pair, <span class=
+    "pagenum"><a id="page130"></a>[pg 130]</span> and other colonists from
+       the valley. The little tracks become plainer and
+       plainer.</p>
+
+    <p>Later still come other wild animals in search of
+    food,&mdash;squirrels will do. The wild animals do not remain
+    in the colony (there are too few squirrels, and they are too
+    hard to catch), but they pass through it, sometimes by day but
+    oftenest by night.</p>
+
+    <p>You might think it was perfectly a matter of chance along
+    which path a bear or a wolf passed, but it was not. He
+    <i>could</i> walk anywhere on the hillside; and sometimes he
+    would be found far out of the paths that the squirrels had
+    begun. But usually, when he was in no haste, he took the
+    easiest path. The easiest one was that which went between the
+    bushes and not through them; along the hillside and not
+    straight up it; around the big rocks and not over them. The
+    wolves and bears and foxes have new and different wants when
+    they come; and they break new paths to the springs where they
+    drink, to the shade where they lie, to the hollow trees where
+    the bees swarm and store the wild honey.</p>
+
+    <p>But the squirrels were the first surveyors of these tracks.
+    The bears and wolves are the engineers, who change the early
+    paths to suit their special convenience.</p>
+
+    <p>By and by the Indian hunter comes to follow the wild game.
+    He, too, takes the easiest trail, the path of least resistance;
+    and he follows the track to the spring that the deer have made,
+    and he drinks there. He is an animal as they are, and he
+    satisfies his animal wants according to the same law that
+    governs them.</p>
+
+    <p>After generations of hunters, Indians, and then white men,
+    there comes a man on horseback looking for a <span class=
+    "pagenum"><a id="page131"></a>[pg 131]</span> house to live in. He, too,
+       follows along the easiest paths and stops at the spring; and
+       near by he finds the place he is looking for. Soon he
+       returns, driving before him herds of cattle and flocks of
+       sheep, which spread over the grassy glades to feed. But
+       everywhere they take the easiest place, the old paths, from
+       the shady tree to the flowing spring. After awhile the
+       hillside is plainly marked with these sheep trails. You can
+       see them now whenever you go into the country, on every
+       hillside.</p>
+
+    <p>Soon there are neighbors who build their homes in the next
+    valley, and a good path must be made between the different
+    houses.</p>
+
+    <p>A few days' work spent in moving the largest stones, in
+    cutting down trees, and in levelling off a few steep slopes,
+    makes a trail along which you can gallop your horse.</p>
+
+    <p>Things move fast now,&mdash;history begins to be made
+    quickly as soon as man takes a hand in it. Soon the trail is
+    not enough: it must be widened so that a wagon-load of boards
+    for a new house can be carried in (for the settler has found a
+    wife). After the first cart-track is made to carry the boards
+    and shingles in, a better road will be needed to haul firewood
+    and grain out (for the wants of the new family have increased,
+    and things must be bought in the neighboring village with
+    money, and money can only be had by selling the products of the
+    farm). By and by the neighborhood is so well inhabited that it
+    is to the advantage of the villages all around it to have good
+    and safe and easy roads there; and the road is declared a
+    public one, and it is regularly kept in repair and improved at
+    the public <span class="pagenum"><a id="page132"></a>[pg 132]</span> expense. Do not forget the
+       squirrels of long ago. They were the projectors of this
+       road. Their successors use it now,&mdash;men and squirrels
+       alike,&mdash;and stop at the spring to drink, and under the
+       huge oaks to rest.</p>
+
+    <p>A few years more, and it becomes to the advantage of all to
+    have a railway through the valley and over the hillside. Then a
+    young surveyor, just graduated from college, comes with his
+    chain-men and flag-men, and finds that the squirrels, and
+    bears, and hunters, and all the rest have picked out the
+    easiest way for him long centuries ago. He makes his map, and
+    soon the chief enigneer and the president of the road drive
+    along in a buggy with a pair of fast horses (frightening the
+    little squirrels off their road-way and into their holes), and
+    the route of the Bear Valley and Quercus Railway is finally
+    selected, and here it is. See! there comes a train along the
+    track. This is the way a railway route grew out of a squirrel
+    path. There are thousands of little steps, but you can trace
+    them, or imagine them, as well as I can tell you.</p>
+
+    <p>It is the same all over the world. Stanley cut a track
+    through the endless African forests. But it lay between the
+    Pygmy villages, along the paths they had made, and through the
+    glades where they fought their battles with the storks.</p>
+
+    <p>Sometimes the first road is a river&mdash;the track is
+    already cut. Try to find out where the settlements in America
+    were in the very early days&mdash;before 1800. You will find
+    them along the Hudson, the Juanita, the St. Lawrence, the
+    James, the Mississippi Rivers. But when these are left, men
+    follow the squirrel-tracks and <span class=
+       "pagenum"><a id="page133"></a>[pg 133]</span> bear-tracks, or the paths
+       of hunters, or the roads of Roman soldiers. It is a standing
+       puzzle to little children why all the great rivers flow past
+       the great towns. (Why do they?) The answer to that question
+       will tell you why the great battles are fought in the same
+       regions; why Egypt has been the coveted prize of a dozen
+       different conquerors (it is the gateway of the East); why
+       our Civil War turned on the possession of the Mississippi
+       River. It is the roadways we fight for, the ways in and out,
+       whether they be land or water. Of course, we really fought
+       for something better than the mere possession of a roadway,
+       but to get what we fought for we had to have the roadway
+       first.</p>
+
+    <p>The great principle at the bottom of everything in Nature is
+    that the fittest survives: or, as I think it is better to say
+    it, in any particular conflict or struggle that thing survives
+    which is the fittest to survive <i>in this particular
+    struggle</i>. This is Mr. Darwin's discovery,&mdash;or one of
+    them,&mdash;and the struggle for existence is a part of the
+    great struggle of the whole universe, and the laws of it make
+    up the methods of Evolution&mdash;of Development.</p>
+
+    <p>It is clear now, is it not, how the railway route is the
+    direct descendant of the tiny squirrel track between two oaks?
+    The process of development we call Evolution, and you can trace
+    it all around you. Why are your skates shaped in a certain way?
+    Why is your gun rifled? Why have soldiers two sets of (now)
+    useless buttons on the skirts of their coats? (I will give you
+    three guesses for this, and the hint that you must think of
+    cavalry soldiers.) Why are eagles' wings of just the size that
+    they are? These and millions <span class="pagenum"><a name=
+    "page134"
+       id="page134"></a>[pg 134]</span> of like questions are to be
+       answered by referring to the principle of development.</p>
+
+    <p>Sometimes it is hard to find the clew. Sometimes the
+    development has gone so far, and the final product has become
+    so complex and special, that it takes a good deal of thinking
+    to find out the real reasons. But they <i>can</i> be found,
+    whether they relate to a fashion, to one of the laws of our
+    country, or to the colors on a butterfly's wing.</p>
+
+    <p>There is a little piece of verse intended to be comic,
+    which, on the contrary, is really serious and philosophical, if
+    you understand it. Learn it by heart, and apply it to all kinds
+    and conditions of things, and see if it does not help you to
+    explain them to yourself....</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p>"And Man grew a thumb for that he had need of
+            it,</p>
+
+            <p>And developed capacities for prey.</p>
+
+            <p>For the fastest men caught the most animals,</p>
+
+            <p>And the fastest animals got away from the most
+            men.</p>
+
+            <p>Whereby all the slow animals were eaten,</p>
+
+            <p>And all the slow men starved to death."</p>
+        </div>
+    </div>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/134.png"><img width="500"
+             src="images/134.png"
+             alt="Train engine."></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="page135"></a>[pg 135]</span>
+
+    <h2>HOW THE SOIL IS MADE</h2>
+
+    <h4>(<span class="sc">From the Formation of Vegetable
+    Mould.</span>)</h4>
+
+    <h3><span class="sc">By</span> CHARLES DARWIN.</h3>
+    <hr class="short">
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/135.png"><img width="200"
+             src="images/135.png"
+             alt="Worms."></a>
+    </div>
+
+    <p>Worms have played a more important part in the history of
+    the world than most persons would at first suppose. In almost
+    all humid countries they are extraordinarily numerous, and for
+    their size possess great muscular power. In many parts of
+    England a weight of more than ten tons (10,516 kilogrammes) of
+    dry earth annually passes through their bodies and is brought
+    to the surface on each acre of land; so that the whole
+    superficial bed of vegetable mould passes through their bodies
+    in the course of every few years. From the collapsing of the
+    old burrows the mould is in constant though slow movement, and
+    the particles composing it are thus rubbed together. By these
+    means fresh surfaces are continually exposed to the action of
+    the carbonic acid in the soil, and of the humus-acids which
+    appear to be still more efficient in the decomposition of
+    rocks. The generation of the humus-acids is probably hastened
+    <span class="pagenum"><a id="page136"></a>[pg 136]</span> during the digestion of the
+       many half-decayed leaves which worms consume. Thus the
+       particles of earth, forming the superficial mould, are
+       subjected to conditions eminently favorable for their
+       decomposition and disintegration. Moreover, the particles of
+       the softer rocks suffer some amount of mechanical
+       trituration in the muscular gizzards of worms, in which
+       small stones serve as mill-stones.</p><br>
+
+    <div class="figleft"
+         style="width:175px;">
+        <a href="images/136.png"><img width="175"
+             src="images/136.png"
+             alt=
+           "DIAGRAM OF THE ALIMENTARY CANAL OF AN EARTH-WORM."></a><br>
+        DIAGRAM OF THE ALIMENTARY CANAL OF AN EARTH-WORM.
+    </div>
+
+    <p>The finely levigated castings, when brought to the surface
+    in a moist condition, flow during rainy weather down any
+    moderate slope; and the smaller particles are washed far down
+    even a gently inclined surface. Castings when dry often crumble
+    into small pellets and these are apt to roll down any sloping
+    surface. Where the land is quite level and is covered with
+    herbage, and where the climate is humid so that much dust
+    cannot be blown away, it appears at first sight impossible that
+    there should be any appreciable amount of sub-aerial
+    denudation; but worm castings are blown, especially while moist
+    and viscid, in one uniform direction by the prevalent winds
+    which are accompanied by rain. By these several means the
+    superficial mould is prevented from accumulating to a great
+    thickness; and a thick bed of mould checks in many ways the
+    disintegration of the underlying rocks and fragments of
+    rock.</p><span class="pagenum"><a id="page137"></a>[pg 137]</span>
+
+    <div class="figright"
+         style="width:250px;">
+        <a href="images/137.png"><img width="250"
+             src="images/137.png"
+             alt="A WORM CASTING, FROM NICE."></a>
+
+        <p>A WORM CASTING, FROM NICE. (Natural Size.)</p>
+    </div>
+
+    <p>The removal of worm-castings by the above means leads to
+    results which are far from insignificant. It has been shown
+    that a layer of earth,.2 of an inch in thickness, is in many
+    places annually brought to the surface per acre; and if a small
+    part of this amount flows, or rolls, or is washed, even for a
+    short distance, down every inclined surface, or is repeatedly
+    blown in one direction, a great effect will be produced in the
+    course of ages. It was found by measurements and calculations
+    that on a surface with a mean inclination of 9° 26', 2.4 cubic
+    inches of earth which had been ejected by worms crossed, in the
+    course of a year, a horizontal line one yard in length; so that
+    two hundred and forty cubic inches would cross a line one
+    hundred yards in length. This latter amount in a damp state
+    would weigh eleven and one-half pounds. Thus, a considerable
+    weight of earth is continually moving down each side of every
+    valley, and will in time reach its bed. Finally, this earth
+    will be transported by the streams flowing in the valleys into
+    the ocean, the great receptacle for all matter denuded from the
+    land. It is known from the amount of sediment annually
+    delivered into the sea by the Mississippi, <span class=
+    "pagenum"><a id="page138"></a>[pg 138]</span> that its enormous
+       drainage-area must on an average be lowered.00263 of an inch
+       each year; and this would suffice in four and a half million
+       years to lower the whole drainage-area to the level of the
+       seashore. So that if a small fraction of the layer of fine
+       earth,.2 of an inch in thickness, which is annually brought
+       to the surface by worms, is carried away, a great result
+       cannot fail to be produced within a period which no
+       geologist considers extremely long.</p>
+
+    <div class="figleft"
+         style="width:400px;">
+        <a href="images/138.png"><img width="400"
+             src="images/138.png"
+             alt=
+           "SECTION THROUGH ONE OF THE DRUIDICAL STONES AT STONEHENGE, SHOWING HOW MUCH IT HAD SUNK INTO THE GROUND."></a>
+
+        <p>SECTION THROUGH ONE OF THE DRUIDICAL STONES AT
+        STONEHENGE, SHOWING HOW MUCH IT HAD SUNK INTO THE
+        GROUND.</p>(Scale, ½ inch to 1 foot.)
+    </div>
+
+    <p>Archaeologists ought to be grateful to worms, as they
+    protect and preserve for an indefinitely long period every
+    object, not liable to decay, which is dropped on the surface of
+    the land, by burying it beneath their castings. Thus, also,
+    many elegant and curious tesselated pavements and other ancient
+    remains have been preserved; though no doubt the worms have in
+    these cases been largely aided by earth washed and blown from
+    the adjoining land, especially when cultivated. The old
+    tesselated pavements have, however, often suffered by having
+    subsided unequally from being unequally undermined by the
+    worms. Even old massive walls may be undermined and subside;
+    and no building is in this respect safe, unless the foundations
+    lie six or seven feet beneath the surface, at a depth at which
+    worms cannot work. It is probable that many <span class=
+    "pagenum"><a id="page139"></a>[pg 139]</span> monoliths and some old
+       walls have fallen down from having been undermined by
+       worms.</p>
+
+    <p>Worms prepare the ground in an excellent manner for the
+    growth of fibrous-rooted plants and for seedlings of all kinds.
+    They periodically expose the mould to the air, and sift it so
+    that no stones larger than the particles which they can swallow
+    are left in it. They mingle the whole intimately together, like
+    a gardener who prepares fine soil for his choicest plants. In
+    this state it is well fitted to retain moisture and to absorb
+    all soluble substances, as well as for the process of
+    nitrification. The bones of dead animals, the harder parts of
+    insects, the shells of land mollusks, leaves, twigs, etc., are
+    before long all buried beneath the accumulated castings of
+    worms, and are thus brought in a more or less decayed state
+    within reach of the roots of plants. Worms likewise drag an
+    infinite number of dead leaves and other parts of plants into
+    their burrows, partly for the sake of plugging them up and
+    partly as food.</p>
+
+    <p>The leaves which are dragged into the burrows as food, after
+    being torn into the finest shreds, partially digested and
+    saturated with the intestinal and urinary secretions, are
+    commingled with much earth. This earth forms the dark-colored,
+    rich humus which almost everywhere covers the surface of the
+    land with a fairly well-defined layer or mantle. Von Hensen
+    placed two worms in a vessel eighteen inches in diameter, which
+    was filled with sand, on which fallen leaves were strewed; and
+    these were soon dragged into their burrows to a depth of three
+    inches. After about six weeks an almost uniform layer of sand,
+    a centimetre <span class="pagenum"><a id="page140"></a>[pg 140]</span> (.4 inch) in thickness, was
+       converted into humus by having passed through the alimentary
+       canals of these two worms. It is believed by some persons
+       that worm-burrows, which often penetrate the ground almost
+       perpendicularly to a depth of five or six feet, materially
+       aid in its drainage; notwithstanding that the viscid
+       castings piled over the mouths of the burrows prevent or
+       check the rain-water directly entering them. They allow the
+       air to penetrate deeply into the ground. They also greatly
+       facilitate the downward passage of roots of moderate size;
+       and these will be nourished by the humus with which the
+       burrows are lined. Many seeds owe their germination to
+       having been covered by castings; and others buried to a
+       considerable depth beneath accumulated castings lie dormant,
+       until at some future time they are accidentally uncovered
+       and germinate.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/140.png"><img width="300"
+             src="images/140.png"
+             alt="A WORM CASTING FROM SOUTH INDIA."></a>
+
+        <p>A WORM CASTING FROM SOUTH INDIA.</p>(Natural Size.)
+    </div>
+
+    <p>Worms are poorly provided with sense-organs, for they cannot
+    be said to see, although they can just distinguish between
+    light and darkness; they are completely deaf, and have only a
+    feeble power of smell; the sense of touch alone is well
+    developed. They can, therefore, learn little about the outside
+    world, and it is surprising that they should exhibit some skill
+    in lining <span class="pagenum"><a id="page141"></a>[pg 141]</span> their burrows with their
+       castings and with leaves, and in the case of some species in
+       piling up their castings into tower-like constructions. But
+       it is far more surprising that they should apparently
+       exhibit some degree of intelligence instead of a mere blind,
+       instinctive impulse, in their manner of plugging up the
+       mouths of their burrows. They act in nearly the same manner
+       as would a man, who had to close a cylindrical tube with
+       different kinds of leaves, petioles, triangles of paper,
+       etc., for they commonly seize such objects by their pointed
+       ends. But with thin objects a certain number are drawn in by
+       their broader ends. They do not act in the same unvarying
+       manner in all cases, as do most of the lower animals; for
+       instance, they do not drag in leaves by their foot-stalks,
+       unless the basil part of the blade is as narrow as the apex,
+       or narrower than it.</p>
+    <hr>
+
+    <p>When we behold a wide, turf-covered expanse, we should
+    remember that its smoothness, on which so much of its beauty
+    depends, is mainly due to all the inequalities having been
+    slowly levelled by worms. It is a marvellous reflection that
+    the whole of the superficial mould over any such expanse has
+    passed, and will again pass, every few years through the bodies
+    of worms. The plough is one of the most ancient and most
+    valuable of man's inventions; but long before he existed the
+    land was in fact regularly ploughed, and, still continues to be
+    thus ploughed by earth-worms. It may be doubted whether there
+    are many other animals which have played so important a part in
+    the history of the world, as have these lowly organized
+    creatures. Some <span class="pagenum"><a id="page142"></a>[pg 142]</span> other animals, however,
+       still more lowly organized, namely, corals, have done far
+       more conspicuous work in having constructed innumerable
+       reefs and islands in the great oceans; but these are almost
+       confined to the tropical zones.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/142.png"><img width="500"
+             src="images/142.png"
+             alt="Mountain peak."></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="page143"></a>[pg 143]</span>
+
+    <h2>ZOÖLOGICAL MYTHS</h2>
+
+    <h4>(<span class="sc">From Facts and Fictions of
+    Zoölogy.</span>)</h4>
+
+    <h3><span class="sc">By</span> ANDREW WILSON.</h3>
+    <hr class="short">
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/143.png"><img width="250"
+             src="images/143.png"
+             alt="Mermaid."></a>
+    </div>
+
+    <p>When the country swain, loitering along some lane, comes to
+    a standstill to contemplate, with awe and wonder, the spectacle
+    of a mass of the familiar "hair-eels" or "hair-worms" wriggling
+    about in a pool, he plods on his way firmly convinced that, as
+    he has been taught to believe, he has just witnessed the
+    results of the transformation of some horse's hairs into living
+    creatures. So familiar is this belief to people of professedly
+    higher culture than the countryman, that the transformation
+    just alluded to has to all, save a few thinking persons and
+    zoölogists, become a matter of the most commonplace kind. When
+    some quarrymen, engaged in splitting up the rocks, have
+    succeeded in dislodging some huge mass of stone, there may
+    sometimes be seen to hop from among the débris a lively toad or
+    frog, which comes to be regarded by the excavators with
+    feelings akin to those of <span class="pagenum"><a name=
+    "page144"
+       id="page144"></a>[pg 144]</span> superstitious wonder and
+       amazement. The animal may or may not be captured; but the
+       fact is duly chronicled in the local newspapers, and people
+       wonder for a season over the phenomenon of a veritable Rip
+       Van Winkle of a frog, which to all appearance, has lived for
+       "thousands of years in the solid rock." Nor do the hair-worm
+       and the frog stand alone in respect of their marvellous
+       origin. Popular zoölogy is full of such marvels. We find
+       unicorns, mermaids, and mermen; geese developed from the
+       shell-fish known as "barnacles"; we are told that crocodiles
+       may weep, and that sirens can sing&mdash;in short, there is
+       nothing so wonderful to be told of animals that people will
+       not believe the tale. Whilst, curiously enough, when they
+       are told of veritable facts of animal life, heads begin to
+       shake and doubts to be expressed, until the zoölogist
+       despairs of educating people into distinguishing fact from
+       fiction, and truth from theories and unsupported beliefs.
+       The story told of the old lady, whose youthful acquaintance
+       of seafaring habits entertained her with tales of the
+       wonders he had seen, finds, after all, a close application
+       in the world at large. The dame listened with delight,
+       appreciation, and belief, to accounts of mountains of sugar
+       and rivers of rum, and to tales of lands where gold and
+       silver and precious stones were more than plentiful. But
+       when the narrator descended to tell of fishes that were able
+       to raise <span class="pagenum"><a id="page145"></a>[pg 145]</span> themselves out of the water
+       in flight, the old lady's credulity began to fancy itself
+       imposed upon; for she indignantly repressed what she
+       considered the lad's tendency to exaggeration, saying,
+       "Sugar mountains may be, and rivers of rum may be, but fish
+       that flee ne'er can be!" Many popular beliefs concerning
+       animals partake of the character of the old lady's opinions
+       regarding the real and fabulous; and the circumstance tells
+       powerfully in favor of the opinion that a knowledge of our
+       surroundings in the world, and an intelligent conception of
+       animal and plant life, should form part of the
+       school-training of every boy and girl, as the most effective
+       antidote to superstitions and myths of every kind.</p>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/144.png"><img width="400"
+             src="images/144.png"
+             alt="FLYING FISH."></a><br>
+        FLYING FISH.
+    </div>
+
+    <p>The tracing of myths and fables is a very interesting task,
+    and it may, therefore, form a curious study, if we endeavor to
+    investigate very briefly a few of the popular and erroneous
+    beliefs regarding lower animals. The belief regarding the
+    origin of the hair-worms is both widely spread and ancient.
+    Shakespeare tells us that</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p class="i22">"Much, is breeding</p>
+
+            <p>Which, like the courser's hair, hath, yet but
+            life,</p>
+
+            <p>And not a serpent's poison."</p>
+        </div>
+    </div>
+
+    <p>The hair-worms certainly present the appearance of long,
+    delicate black hairs, which move about with great activity
+    amidst the mud of pools and ditches. These worms, in the early
+    stages of their existence, inhabit the bodies of insects, and
+    may be found coiled up within the grasshopper, which thus gives
+    shelter to a guest exceeding many times the length of the body
+    of its host. Sooner or later the hair-worm, or <i>Gordius</i>
+    <span class="pagenum"><a id="page146"></a>[pg 146]</span> <i>aquaticus</i> as the
+       naturalist terms it, leaves the body of the insect, and lays
+       its eggs, fastened together in long strings, in water. From
+       each egg a little creature armed with minute hooks is
+       produced, and this young hair-worm burrows its way into the
+       body of some insect, there to repeat the history of its
+       parent. Such is the well-ascertained history of the
+       hair-worm, excluding entirely the popular belief in its
+       origin. There certainly does exist in science a theory known
+       as that of "spontaneous generation," which, in ancient
+       times, accounted for the production of insects and other
+       animals by assuming that they were produced in some
+       mysterious fashion out of lifeless matter. But not even the
+       most ardent believer in the extreme modification of this
+       theory which holds a place in modern scientific belief,
+       would venture to maintain the production of a hair-worm by
+       the mysterious vivification of an inert substance such as a
+       horse's hair.</p>
+
+    <p>The expression "crocodile's tears" has passed into common
+    use, and it therefore may be worth while noting the probable
+    origin of this myth. Shakespeare, with that wide extent of
+    knowledge which enabled him to draw similes from every
+    department of human thought, says that</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p class="i22">"Gloster's show</p>
+
+            <p>Beguiles him, as the mournful crocodile</p>
+
+            <p>With sorrow snares relenting passengers."</p>
+        </div>
+    </div>
+
+    <p>The poet thus indicates the belief that not only do
+    crocodiles shed tears, but that sympathizing passengers,
+    turning to commiserate the reptile's woes, are seized and
+    destroyed by the treacherous creatures. That quaint and
+    credulous old author&mdash;the earliest writer
+          <span class="pagenum"><a id="page147"></a>[pg 147]</span> of English prose&mdash;Sir
+       John Mandeville, in his "Voiage," or account of his
+       "Travile," published about 1356&mdash;in which, by the way,
+       there are to be found accounts of not a few wonderful things
+       in the way of zoölogical curiosities&mdash;tells us that in
+       a certain "contre and be all yonde, ben great plenty of
+       Crokodilles, that is, a manner of a long Serpent as I have
+       seyed before." He further remarks that "these Serpents slew
+       men," and devoured them, weeping; and he tells us, too, that
+       "whan thei eaten thei meven (move) the over jowe (upper
+       jaw), and nought the nether (lower) jowe: and thei have no
+       tonge (tongue)." Sir John thus states two popular beliefs of
+       his time and of days prior to his age, namely, that
+       crocodiles move their upper jaws, and that a tongue was
+       absent in these animals.</p>
+
+    <div class="figright"
+         style="width:400px;">
+        <a href="images/147.png"><img width="400"
+             src="images/147.png"
+             alt="CROCODILE."></a><br>
+        CROCODILE.
+    </div>
+
+    <p>As regards the tears of the crocodile, no foundation of fact
+    exists for the belief in such sympathetic exhibitions. But a
+    highly probable explanation may be given of the manner in which
+    such a belief originated. These reptiles unquestionably emit
+    very loud and singularly plaintive cries, compared by some
+    travellers to the mournful howling of dogs. The earlier and
+    credulous <span class="pagenum"><a id="page148"></a>[pg 148]</span> travellers would very
+       naturally associate tears with these cries, and, once begun,
+       the supposition would be readily propagated, for error and
+       myth are ever plants of quick growth. The belief in the
+       movement of the upper jaw rests on apparent basis of fact.
+       The lower jaw is joined to the skull very far back on the
+       latter, and the mouth-opening thus comes to be singularly
+       wide; whilst, when the mouth opens, the skull and upper jaw
+       are apparently observed to move. This is not the case,
+       however; the apparent movement arising from the manner in
+       which the lower jaw and the skull are joined together. The
+       belief in the absence of the tongue is even more readily
+       explained. When the mouth is widely opened, no tongue is to
+       be seen. This organ is not only present, but is, moreover,
+       of large size; it is, however, firmly attached to the floor
+       of the mouth, and is specially adapted, from its peculiar
+       form and structure, to assist these animals in the capture
+       and swallowing of their prey.</p>
+
+    <p>One of the most curious fables regarding animals which can
+    well be mentioned, is that respecting the so-called "Bernicle"
+    or "Barnacle Geese," which by the naturalists and educated
+    persons of the Middle Ages were believed to be produced by
+    those little Crustaceans named "Barnacles." With the
+    "Barnacles" every one must be familiar who has examined the
+    floating driftwood of the sea-beach, or who has seen ships
+    docked in a seaport town. A barnacle is simply a kind of crab
+    enclosed in a triangular shell, and attached by a fleshy stalk
+    to fixed objects. If the barnacle is not familiar to readers,
+    certain near relations of these animals must be well known, by
+    sight at least, as amongst the most <span class=
+    "pagenum"><a id="page149"></a>[pg 149]</span> familiar denizens of our
+       sea-coast. These latter are the "Sea-Acorn," or Balani,
+       whose little conical shells we crush by hundreds as we walk
+       over the rocks at low-water mark; whilst every wooden pile
+       immersed in the sea becomes coated in a short time with a
+       thick crust of the "Sea-Acorns." If we place one of these
+       little animals, barnacle, or sea-acorn&mdash;the latter
+       wanting the stalk of the former&mdash;in its native waters,
+       we shall observe a beautiful little series of feathery
+       plumes to wave backward and forward, and ever and anon to be
+       quickly withdrawn into the secure recesses of the shell.
+       These organs are the modified feet of the animal, which not
+       only serve for sweeping food-particles into the mouth, but
+       act also as breathing-organs. We may, therefore, find it a
+       curious study to inquire through what extraordinary
+       transformation and confusion of ideas such an animal could
+       be credited with giving origin to a veritable goose; and the
+       investigation of the subject will also afford a singularly
+       apt illustration of the ready manner in which the fable of
+       one year or period becomes transmitted and transformed into
+       the secure and firm belief of the next.</p>
+
+    <p>We may begin our investigation by inquiring into some of the
+    opinions which were entertained on this subject and ventilated
+    by certain old writers. Between 1154 and 1189 Giraldus
+    Cambrensis, in a work entitled "Topographia Hiberniae," written
+    in Latin, remarks concerning "many birds which are called
+    Bernacae: against nature, nature produces them in a most
+    extraordinary way. They are like marsh geese, but somewhat
+    smaller. They are produced from fir timber tossed along the
+    sea, and are at first like gum. Afterward <span class=
+    "pagenum"><a id="page150"></a>[pg 150]</span> they hang down by their
+       beaks, as if from a seaweed attached to the timber,
+       surrounded by shells, in order to grow more freely,"
+       Giraldus is here evidently describing the barnacles
+       themselves. He continues: "Having thus, in process of time,
+       been clothed with a strong coat of feathers, they either
+       fall into the water or fly freely away into the air. They
+       derive their food and growth from the sap of the wood or the
+       sea, by a secret and most wonderful process of alimentation.
+       I have frequently, with my own eyes, seen more than a
+       thousand of these small bodies of birds, hanging down on the
+       seashore from one piece of timber, enclosed in shells, and
+       already formed." Here, again, our author is speaking of the
+       barnacles themselves, with which he naturally confuses the
+       geese, since he presumes the Crustaceans are simply geese in
+       an undeveloped state. He further informs his readers that,
+       owing to their presumably marine origin, "bishops and
+       clergymen in some parts of Ireland do not scruple to dine
+       off these birds at the time of fasting, because they are not
+       flesh, nor born of flesh," although for certain other and
+       theological reasons, not specially requiring to be discussed
+       in the present instance, Giraldus disputes the legality of
+       this practice of the Hibernian clerics.</p>
+
+    <p>In the year 1527 appeared "The Hystory and Croniclis of
+    Scotland, with the cosmography and dyscription thairof,
+    compilit be the noble Clerk Maister Hector Boece, Channon of
+    Aberdene." Boece's "History" was written in Latin; the title we
+    have just quoted being that of the English version of the work
+    (1540), which title further sets forth that Boece's work was
+    "Translait laitly in our vulgar and commoun langage be
+    <span class="pagenum"><a id="page151"></a>[pg 151]</span> Maister Johne Bellenden,
+       Archedene of Murray, And Imprentit in Edinburgh, be me
+       Thomas Davidson, prenter to the Kyngis nobyll grace." In
+       this learned work the author discredits the popular ideas
+       regarding the origin of the geese. "Some men belevis that
+       thir clakis (geese) growis on treis be the nebbis (bills).
+       Bot thair opinoun is vane. And becaus the nature and
+       procreatioun of thir clakis is strange, we have maid na
+       lytyll laboure and deligence to serche ye treuth and verite
+       yairof, we have salit (sailed) throw ye seis quhare thir
+       clakis ar bred, and I fynd be gret experience, that the
+       nature of the seis is mair relevant caus of thair
+       procreatioun than ony uthir thyng." According to Boece,
+       then, "the nature of the seis" formed the chief element in
+       the production of the geese, and our author proceeds to
+       relate how "all treis (trees) that ar casein in the seis be
+       proces of tyme apperis first wormeetin (worm-eaten), and in
+       the small boris and hollis (holes) thairof growis small
+       worms." Our author no doubt here alludes to the ravages of
+       the Teredo, or ship-worm, which burrows into timber, and
+       with which the barnacles themselves are thus confused. Then
+       he continues, the "wormis" first "schaw (show) thair heid
+       and feit, and last of all thay schaw thair plumis and
+       wyngis. Finaly, quhen thay ar cumyn to the just mesure and
+       quantite of geis, thay fle in the aire as othir fowlis dois,
+       as was notably provyn, in the yeir of God ane thousand iii
+       hundred lxxxx, in sicht of mony pepyll, besyde the castell
+       of Petslego." On the occasion referred to, Boece tells us
+       that a great tree was cast on shore, and was divided, by
+       order of the "laird" of the ground, by means of a saw.
+       Wonderful to relate, the tree was found not <span class=
+       "pagenum"><a id="page152"></a>[pg 152]</span> merely to be riddled with a
+       "multitude of wormis," throwing themselves out of the holes
+       of the tree, but some of the "wormis" had "baith heid, feit,
+       and wyngis," but, adds the author, "they had no fedderis
+       (feathers)."</p>
+
+    <p>Unquestionably, either "the scientific use of the
+    imagination" had operated in this instance in inducing the
+    observers to believe that in this tree, riddled by the
+    ship-worms and possibly having barnacles attached to it, they
+    beheld young geese; or Boece had construed the appearances
+    described as those representing the embryo stages of the
+    barnacle geese.</p>
+
+    <p>Boece further relates how a ship named the Christofir was
+    brought to Leith, and was broken down because her timbers had
+    grown old and failing. In these timbers were beheld the same
+    "wormeetin" appearances, "all the hollis thairof" being "full
+    of geis." Boece again most emphatically rejects the idea that
+    the "geis" were produced from the wood of which the timbers
+    were composed, and once more proclaims his belief that the
+    "nature of the seis resolvit in geis" may be accepted as the
+    true and final explanation of their origin. A certain "Maister
+    Alexander Galloway" had apparently strolled with the historian
+    along the sea-coast, the former giving "his mynd with maist
+    ernist besynes to serche the verite of this obscure and mysty
+    dowtis." Lifting up a piece of tangle, they beheld the seaweed
+    to be hanging full of mussel-shells from the root to the
+    branches. Maister Galloway opened one of the mussel-shells, and
+    was "mair astonis than afore" to find no fish therein, but a
+    perfectly shaped "foule, smal and gret," as corresponded to the
+    "quantity of the <span class="pagenum"><a id="page153"></a>[pg 153]</span> shell." And once again
+       Boece draws the inference that the trees or wood on which
+       the creatures are found have nothing to do with the origin
+       of the birds; and that the fowls are begotten of the
+       "occeane see, quhilk," concludes our author, "is the caus
+       and production of mony wonderful thingis."</p>
+
+    <p>More than fifty years after the publication of Boece's
+    "History," old Gerard of London, the famous "master in
+    chirurgerie" of his day, gave an account of the barnacle goose,
+    and not only entered into minute particulars of its growth and
+    origin, but illustrated its manner of production by means of
+    the engraver's art of his day. Gerard's "Herball," published in
+    1597, thus contains, amongst much that is curious in medical
+    lore, a very quaint piece of zoölogical history. He tells us
+    that "in the north parts of Scotland, and the Hands adjacent,
+    called Orchades (Orkneys)," are found "certaine trees, whereon
+    doe growe certaine shell fishes, of a white colour tending to
+    russet; wherein are conteined little living creatures: which
+    shels in time of maturitie doe open, and out of them grow those
+    little living foules whom we call Barnakles, in the north of
+    England Brant Geese, and in Lancashire tree Geese; but the
+    other that do fall upon the land, perish, and come to nothing:
+    thus much by the writings of others, and also from the mouths
+    of people of those parts, which may," concludes Gerard, "very
+    well accord with truth."</p>
+
+    <p>Not content with hearsay evidence, however, Gerard relates
+    what his eyes saw and hands touched. He describes how on the
+    coasts of a certain "small Hand in Lancashire called Pile of
+    Foulders" (probably Peel <span class="pagenum"><a name=
+    "page154"
+       id="page154"></a>[pg 154]</span> Island), the wreckage of
+       ships is cast up by the waves, along with the trunks and
+       branches "of old and rotten trees." On these wooden
+       rejectamenta "a certaine spume or froth" grows, according to
+       Gerard. This spume "in time breedeth unto certaine shels, in
+       shape like those of the muskle, but sharper pointed, and of
+       a whitish color." This description, it may be remarked,
+       clearly applies to the barnacles themselves. Gerard then
+       continues to point out how, when the shell is perfectly
+       formed, it "gapeth open, and the first thing that appeereth
+       is the foresaid lace or string"&mdash;the substance
+       described by Gerard as contained within the
+       shell&mdash;"next come the legs of the Birde hanging out;
+       and as it groweth greater, it openeth the shell by degrees,
+       till at length it is all come forth, and hangeth only by the
+       bill; in short space after it commeth to full maturitie, and
+       falleth into the sea, where it gathereth feathers, and
+       groweth to a foule, bigger than a Mallard, and lesser than a
+       Goose, having blacke legs and bill or beake, and feathers
+       blacke and white ... which the people of Lancashire call by
+       no other name than a tree Goose."</p>
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/154.png"><img width="250"
+             src="images/154.png"
+             alt="FIG. 1. THE BARNACLE TREE."></a><br>
+        FIG. 1. THE BARNACLE TREE.<br>
+        (From Gerard's "Herball.")
+    </div>
+
+    <p>Accompanying this description is the engraving of the
+    barnicle tree (Fig. 1) bearing its geese progeny. From the open
+    shells in two cases, the little geese are seen protruding,
+    whilst several of the fully-fledged fowls <span class=
+    "pagenum"><a id="page155"></a>[pg 155]</span> are disporting themselves
+       in the sea below. Gerard's concluding piece of information,
+       with its exordium, must not be omitted. "They spawne," says
+       the wise apothecary, "as it were, in March or Aprill; the
+       Geese are found in Maie or June, and come to fulnesse of
+       feathers in the moneth after. And thus hauing, through God's
+       assistance, discoursed somewhat at large of Grasses, Herbes,
+       Shrubs, Trees, Mosses, and certaine excrescences of the
+       earth, with other things moe incident to the Historic
+       thereof, we conclude and end our present volume, with this
+       woonder of England. For which God's name be euer honored and
+       praised." It is to be remarked that Gerard's description of
+       the goose-progeny of the barnacle tree exactly corresponds
+       with the appearance of the bird known to ornithologists as
+       the "barnacle-goose"; and there can be no doubt that,
+       skilled as was this author in the natural history lore of
+       his day, there was no other feeling in his mind than that of
+       firm belief in and pious wonder at the curious relations
+       between the shells and their fowl-offspring. Gerard thus
+       attributes the origin of the latter to the barnacles. He
+       says nothing of the "wormeetin" holes and burrows so
+       frequently mentioned by Boece, nor would he have agreed with
+       the latter in crediting the "nature of the occeane see" with
+       their production, save in so far as their barnacle-parents
+       lived and existed in the waters of the ocean.</p>
+
+    <p>The last account of this curious fable which we may allude
+    to in the present instance is that of Sir Robert Moray, who, in
+    his work entitled "A Relation concerning Barnacles," published
+    in the <i>Philosophical Transactions</i> of the Royal Society
+    in 1677-78, gives a <span class="pagenum"><a id="page156"></a>[pg 156]</span> succinct account of these
+       crustaceans and their bird-progeny. Sir Robert is described
+       as "lately one of his Majesties Council for the Kingdom of
+       Scotland," and we may therefore justly assume his account to
+       represent that of a cultured, observant person of his day
+       and generation. The account begins by remarking that the
+       "most ordinary trees" found in the western islands of
+       Scotland "are Firr and Ash." "Being," continues Sir Robert,
+       "in the Island of East (Uist), I saw lying upon the shore a
+       cut of a large Firr tree of about 2-1/2 foot diameter, and 9
+       or 10 foot long; which had lain so long out of the water
+       that it was very dry: And most of the shells that had
+       formerly cover'd it, were worn or rubb'd off. Only on the
+       parts that lay next the ground, there still hung multitudes
+       of little Shells; having within them little Birds, perfectly
+       shap'd, supposed to be Barnacles." Here again the
+       description applies to the barnacles; the "little birds"
+       they are described as containing being of course the bodies
+       of the shell-fish.</p>
+
+    <p>"The Shells," continues the narrator, "hang at the Tree by a
+    Neck longer than the Shell;" this "neck" being represented by
+    the stalk of the barnacle. The neck is described as being
+    composed "of a kind of filmy substance, round, and hollow, and
+    creased, not unlike the Wind-pipe of a Chicken; spreading out
+    broadest where it is fastened to the Tree, from which it seems
+    to draw and convey the matter which serves for the growth and
+    vegetation of the Shell and the little Bird within it." Sir
+    Robert Moray therefore agrees in respect of the manner of
+    nourishment of the barnacles with the opinion of Giraldus
+    already quoted. The <span class="pagenum"><a id="page157"></a>[pg 157]</span> author goes on to describe
+       the "Bird" found in every shell he opened; remarking that
+       "there appeared nothing wanting as to the internal parts,
+       for making up a perfect Sea-fowl: every little part
+       appearing so distinctly, that the whole looked like a large
+       Bird seen through a concave or diminishing Glass, colour and
+       feature being everywhere so clear and neat." The "Bird" is
+       most minutely described as to its bill, eyes, head, neck,
+       breast, wings, tail, and feet, the feathers being
+       "everywhere perfectly shaped, and blackish-coloured. All
+       being dead and dry," says Sir Robert, "I did not look after
+       the Internal parts of them," a statement decidedly
+       inconsistent with his previous assertion as to the perfect
+       condition of the "internal parts"; and he takes care to add,
+       "nor did I ever see any of the little Birds alive, nor met
+       with anybody that did. Only some credible persons," he
+       concludes, "have assured me they have seen some as big as
+       their fist."</p>
+
+    <div class="figright"
+         style="width:400px;">
+        <a href="images/157.png"><img width="400"
+             src="images/157.png"
+             alt="FIG. 2. BARNACLE TREE."></a><br>
+        FIG. 2. BARNACLE TREE.<br>
+        (From Munster's "Cosmography.")
+    </div>
+
+    <p>This last writer thus avers that he saw little birds within
+    the shells he clearly enough describes as those of the
+    barnacles. We must either credit Sir Robert <span class=
+    "pagenum"><a id="page158"></a>[pg 158]</span> with describing what he
+       never saw, or with misconstruing what he did see. His
+       description of the goose corresponds with that of the
+       barnacle goose, the reputed progeny of the shells; and it
+       would, therefore, seem that this author, with the myth at
+       hand, saw the barnacles only with the eyes of a credulous
+       observer, and thus beheld, in the inside of each
+       shell&mdash;if, indeed, his research actually extended thus
+       far&mdash;the reproduction in miniature of a goose, with
+       which, as a mature bird, he was well acquainted.</p>
+
+    <p>On p. 157 is a woodcut, copied from Munster's "Cosmography"
+    (1550), a very popular book in its time, showing the tree with
+    its fruit, and the geese which are supposed to have just
+    escaped from it.</p>
+
+    <p>This historical ramble may fitly preface what we have to say
+    regarding the probable origin of the myth. By what means could
+    the barnacles become credited with the power of producing the
+    well-known geese? Once started, the progress and growth of the
+    myth are easily accounted for. The mere transmission of a fable
+    from one generation or century to another is a simply explained
+    circumstance, and one exemplified by the practices of our own
+    times. The process of accretion and addition is also well
+    illustrated in the perpetuation of fables; since the tale is
+    certain to lose nothing in its historical journey, but, on the
+    contrary, to receive additional elaboration with increasing
+    age. Professor Max Müller, after discussing various theories of
+    the origin of the barnacle myth, declares in favor of the idea
+    that confusion of language and alteration of names lie at the
+    root of the error. The learned author of the "Science of
+    Language" argues that the true barnacles <span class=
+    "pagenum"><a id="page159"></a>[pg 159]</span> were named, properly
+       enough, Bernaculae, and lays stress on the fact that
+       Bernicle geese were first caught in Ireland. That country
+       becomes <i>Hibernia</i> in Latin, and the Irish geese were
+       accordingly named Hibernicae, or Hiberniculae. By the
+       omission of the first syllable&mdash;no uncommon operation
+       for words to undergo&mdash;we obtain the name Berniculae for
+       the geese, this term being almost synonymous with the name
+       Bernaculae already applied, as we have seen, to the
+       barnacles. Bernicle geese and bernicle shells, confused in
+       name, thus became confused in nature; and, once started, the
+       ordinary process of growth was sufficient to further
+       intensify, and render more realistic, the story of the
+       bernicle tree and its wonderful progeny.</p>
+
+    <p>By way of a companion legend to that of the barnacle tree,
+    we may select the story of the "Lamb Tree" of Cathay, told by
+    Sir John Mandeville, whose notes of travel regarding
+    crocodiles' tears, and other points in the conformation of
+    these reptiles, have already been referred to. Sir John, in
+    that chapter of his work which treats "Of the Contries and Yles
+    that ben bezonde the Lond of Cathay; and of the Frutes there,"
+    etc., relates that in Cathay "there growethe a manner of Fruyt,
+    as thoughe it were Gowrdes: and whan thei ben rype, men kutten
+    (cut) hem a to (them in two), and men fyndem with inne a
+    lytylle Best (beast), in Flessche in Bon and Blode (bone and
+    blood) as though it were a lytylle Lomb (lamb) with outen wolle
+    (without wool). And men eaten both the Frut and the Best; and
+    that," says Sir John, "is a great marveylle. Of that frut," he
+    continues, "I have eten; alle thoughe it were
+    wondirfulle"&mdash;this being added, no doubt, from an idea
+    <span class="pagenum"><a id="page160"></a>[pg 160]</span> that there might possibly
+       be some stay-at-home persons who would take Sir John's
+       statement <i>cum grano salis</i>. "But," adds this worthy
+       "knyght of Ingolond," "I knowe wel that God is marveyllous
+       in His Werkes." Not to be behind the inhabitants of Cathay
+       in a tale of wonders, the knight related to these Easterns
+       "als gret a marveylle to hem that is amonges us; and that
+       was of the Bernakes. For I tolde him hat in oure Countree
+       weren Trees that beren a Fruyt, that becomen Briddes (birds)
+       fleeynge: and tho that fellen in the Water lyven (live); and
+       thei that fallen on the Erthe dyen anon: and thei ben right
+       gode to mannes mete (man's meat). And here had thei als gret
+       marvayle," concludes Sir John, "that sume of hem trowed it
+       were an impossible thing to be." Probably the inhabitants of
+       Cathay, knowing their own weakness as regards the lamb tree,
+       might possess a fellow-feeling for their visitor's
+       credulity, knowing well, from experience, the readiness with
+       which a "gret marvayle" could be evolved and sustained.</p>
+
+    <p>Passing from the sphere of the mythical and marvellous as
+    represented in mediaeval times, we may shortly discuss a
+    question, which, of all others, may justly claim a place in the
+    records of zoölogical curiosities&mdash;namely, the famous and
+    oft-repeated story of the "Toad from the solid rock," as the
+    country newspapers style the incident. Regularly, year by year,
+    and in company with the reports of the sea-serpent's
+    reappearance, we may read of the discoveries of toads and frogs
+    in situations and under circumstances suggestive of a singular
+    vitality on the part of the amphibians, of more than usual
+    credulity on the part of the hearers, <span class=
+    "pagenum"><a id="page161"></a>[pg 161]</span> or of a large share of
+       inventive genius in the narrators of such tales. The
+       question possesses for every one a certain degree of
+       interest, evoked by the curious and strange features
+       presented on the face of the tales. And it may therefore not
+       only prove an interesting but also a useful study, if we
+       endeavor to arrive at some just and logical conceptions of
+       these wonderful narrations.</p>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/161.png"><img width="600"
+             src="images/161.png"
+             alt="Discovering toad."></a>
+    </div>
+
+    <p>Instances of the discovery of toads and frogs in solid rocks
+    need not be specially given; suffice it to say, that these
+    narratives are repeated year by year with little variation. A
+    large block of stone or face of rock is detached from its site,
+    and a toad or frog is seen hereafter to be hopping about in its
+    usual lively manner. The conclusion to which the bystanders
+    invariably come is that the animal must have been contained
+    within the rock, and that it was liberated by the dislodgement
+    of the mass. Now, in many instances, cases of the appearance of
+    toads during quarrying <span class="pagenum"><a id="page162"></a>[pg 162]</span> operations have been found,
+       on close examination, to present no evidence whatever that
+       the appearance of the animals was due to the dislodgement of
+       the stones. A frog or toad may be found hopping about among
+       some recently formed débris, and the animal is at once
+       seized upon and reported as having emerged from the rocks
+       into the light of day. There is in such a case not the
+       slightest ground for supposing any such thing; and the
+       animal may more reasonably be presumed to have simply hopped
+       into the débris from its ordinary habitat. But laying aside
+       narratives of this kind, which lose their plausibility under
+       a very commonplace scrutiny, there still exist cases,
+       reported in an apparently exact and truthful manner, in
+       which these animals have been alleged to appear from the
+       inner crevices of rocks after the removal of large masses of
+       the formations. We shall assume these latter tales to
+       contain a plain, unvarnished statement of what was observed,
+       and deal with the evidence they present on this footing.</p>
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/162.png"><img width="250"
+             src="images/162.png"
+             alt="A TOAD."></a><br>
+        A TOAD.
+    </div>
+
+    <p>One or two notable examples of such verified tales are
+    related by Smellie, in his "Philosophy of Natural History."
+    Thus, in the "Memoirs of the French Academy of Sciences" for
+    1719, a toad is described as having been found in the heart of
+    an elm tree; and another is stated to have been found in the
+    heart of an old oak tree, in 1731, near Nantz. The condition
+    <span class="pagenum"><a id="page163"></a>[pg 163]</span> of the trees is not
+       expressly stated, nor are we afforded any information
+       regarding the appearance of the toads&mdash;particulars of
+       considerable importance in view of the suggestions and
+       explanations to be presently brought forward. Smellie
+       himself, while inclined to be sceptical in regard to the
+       truth or exactness of many of the tales told of the vitality
+       of toads, regards the matter as affording food for
+       reflection, since he remarks, "But I mean not to persuade,
+       for I cannot satisfy myself; all I intend is, to recommend
+       to those gentlemen who may hereafter chance to see such rare
+       phenomena, a strict examination of every circumstance that
+       can throw light upon a subject so dark and mysterious; for
+       the vulgar, ever inclined to render uncommon appearances
+       still more marvellous, are not to be trusted."</p>
+
+    <p>This author strikes the key-note of the inquiry in his
+    concluding words, and we shall find that the explanation of the
+    matter really lies in the clear understanding of what are the
+    probabilities, and what the actual details, of the cases
+    presented for consideration. We may firstly, then, glance at a
+    few of the peculiarities of the frogs and toads, regarded from
+    a zoölogical point of view. As every one knows, these animals
+    emerge from the egg in the form of little fish-like "tadpoles,"
+    provided with outside gills, which are soon replaced by inside
+    gills, resembling those of fishes. The hind legs are next
+    developed, and the fore limbs follow a little later; whilst,
+    with the development of lungs, and the disappearance of the
+    gills and tail, the animal leaves the water, and remains for
+    the rest of its life an air-breathing, terrestrial animal.
+    Then, <span class="pagenum"><a id="page164"></a>[pg 164]</span> secondly, in the adult frog
+       or toad, the naturalist would point to the importance of the
+       skin as not only supplementing, but, in some cases, actually
+       supplanting the work of the lungs as the breathing organ.
+       Frogs and toads will live for months under water, and will
+       survive the excision of the lungs for like periods; the skin
+       in such cases serving as the breathing surface. A third
+       point worthy of remembrance is included in the facts just
+       related, and is implied in the information that these
+       animals can exist for long periods without food, and with
+       but a limited supply of air. We can understand this
+       toleration on the part of these animals when we take into
+       consideration their cold-blooded habits, which do not
+       necessitate, and which are not accompanied by, the amount of
+       vital activity we are accustomed to note in higher animals.
+       And, as a last feature in the purely scientific history of
+       the frogs and toads, it may be remarked that these animals
+       are known to live for long periods. One pet toad is
+       mentioned by a Mr. Arscott as having attained, to his
+       knowledge, the age of thirty-six years; and a greater age
+       still might have been recorded of this specimen, but for the
+       untoward treatment it sustained at the hands, or rather
+       beak, of a tame raven. In all probability it may be safely
+       assumed that, when the conditions of life are favorable,
+       these creatures may attain a highly venerable
+       age&mdash;regarding the lapse of time from a purely human
+       and interested point of view.</p>
+
+    <p>We may now inquire whether or not the foregoing
+    considerations may serve to throw any light upon the tales of
+    the quarryman. The first point to which attention may be
+    directed is that involved in the statement <span class=
+    "pagenum"><a id="page165"></a>[pg 165]</span> that the amphibian has been
+       imprisoned in a <i>solid</i> rock. Much stress is usually
+       laid on the fact that the rock was solid; this fact being
+       held to imply the great age, not to say antiquity, of the
+       rock and its supposed tenant. The impartial observer, after
+       an examination of the evidence presented, will be inclined
+       to doubt greatly the justification for inserting the
+       adjective "solid"; for usually no evidence whatever is
+       forthcoming as to the state of the rock prior to its
+       removal. No previous examination of the rock is or can be
+       made, from the circumstance that no interest can possibly
+       attach to its condition until its removal reveals the
+       apparent wonder it contained, in the shape of the live toad.
+       And it is equally important to note that we rarely, if ever,
+       find mention of any examination of the rock being made
+       subsequently to the discovery. Hence, a first and grave
+       objection may be taken to the validity of the supposition
+       that the rock was solid, and it may be fairly urged that on
+       this supposition the whole question turns and depends. For
+       if the rock cannot be proved to have been impermeable to and
+       barred against the entrance of living creatures, the
+       objector may proceed to show the possibility of the toad
+       having gained admission, under certain notable
+       circumstances, to its prison-house.</p>
+
+    <p>The frog or toad in its young state, and having just entered
+    upon its terrestrial life, is a small creature, which could,
+    with the utmost ease, wriggle into crevices and crannies of a
+    size which would almost preclude such apertures being noticed
+    at all. Gaining access to a roomier crevice or nook within, and
+    finding there a due supply of air, along with a dietary
+    consisting chiefly <span class="pagenum"><a id="page166"></a>[pg 166]</span> of insects, the animal
+       would grow with tolerable rapidity, and would increase to
+       such an extent that egress through its aperture of entrance
+       would become an impossibility. Next, let us suppose that the
+       toleration of the toad's system to starvation and to a
+       limited supply of air is taken into account, together with
+       the fact that these creatures will hibernate during each
+       winter, and thus economize, as it were, their vital activity
+       and strength; and after the animal has thus existed for a
+       year or two&mdash;no doubt under singularly hard
+       conditions&mdash;let us imagine that the rock is split up by
+       the wedge and lever of the excavator. We can then readily
+       enough account for the apparently inexplicable story of "the
+       toad in the rock." "There is the toad and here is the solid
+       rock," say the gossips. "There is an animal which has
+       singular powers of sustaining life under untoward
+       conditions, and which, in its young state, could have gained
+       admittance to the rock through a mere crevice," says the
+       naturalist in reply. Doubtless, the great army of the
+       unconvinced may still believe in the tale as told them; for
+       the weighing of evidence and the placing <i>pros</i> and
+       <i>cons</i> in fair contrast are not tasks of congenial or
+       wonted kind in the ordinary run of life. Some people there
+       will be who will believe in the original solid rock and its
+       toad, despite the assertion of the geologists that the
+       earliest fossils of toads appear in almost the last-formed
+       rocks, and that a live toad in rocks of very ancient
+       age&mdash;presuming, according to the popular belief, that
+       the animal was enclosed when the rock was formed&mdash;would
+       be as great an anomaly and wonder as the mention, as an
+       historical fact, of an express train or the telegraph in the
+       days of the patriarchs. <span class="pagenum"><a name=
+       "page167"
+       id="page167"></a>[pg 167]</span> In other words, the live
+       toad which hops out of an Old Red Sandstone rock must be
+       presumed, on the popular belief, to be older by untold ages
+       than the oldest fossil frogs and toads. The reasonable mind,
+       however, will ponder and consider each feature of the case,
+       and will rather prefer to countenance a supposition based on
+       ordinary experience, than an explanation brought ready-made
+       from the domain of the miraculous; whilst not the least
+       noteworthy feature of these cases is that included in the
+       remark of Smellie, respecting the tendency of uneducated and
+       superstitious persons to magnify what is uncommon, and in
+       his sage conclusion that as a rule such persons in the
+       matter of their relations "are not to be trusted."</p>
+
+    <p>But it must also be noted that we possess valuable evidence
+    of a positive and direct kind bearing on the duration of life
+    in toads under adverse circumstances. As this evidence tells
+    most powerfully against the supposition that the existence of
+    those creatures can be indefinitely prolonged, it forms of
+    itself a veritable court of appeal in the cases under
+    discussion. The late Dr. Buckland, curious to learn the exact
+    extent of the vitality of the toad, caused, in the year 1825,
+    two large blocks of stone to be prepared. One of the blocks was
+    taken from the oölite limestone, and in this first stone twelve
+    cells were excavated. Each cell was one foot deep and five
+    inches in diameter. The mouth of each cell was grooved so as to
+    admit of two covers being placed over the aperture; the first
+    or lower cover being of glass, and the upper one of slate. Both
+    covers were so adapted that they could be firmly luted down
+    with clay or putty; the object of this double protection
+    <span class="pagenum"><a id="page168"></a>[pg 168]</span> being that the slate cover
+       could be raised so as to inspect the contained object
+       through the closed glass cover without admitting air. In the
+       second or sandstone block, a series of twelve cells was also
+       excavated; these latter cells being, however, of smaller
+       size than those of the limestone block, each cell being only
+       six inches in depth by five inches in diameter. These cells
+       were likewise fitted with double covers.</p>
+
+    <p>On November 26th, 1825, a live toad&mdash;kept for some time
+    previously to insure its being healthy&mdash;was placed in each
+    of the twenty-four cells. The largest specimen weighed 1185
+    grains, and the smallest 115 grains. The stones and the immured
+    toads were buried on the day mentioned, three feet deep, in Dr.
+    Buckland's garden. There they lay until December 10th, 1826,
+    when they were disinterred and their tenants examined. All the
+    toads in the smaller cells of the sandstone block were dead,
+    and from the progress of decomposition it was inferred that
+    they had succumbed long before the date of disinterment. The
+    majority of the toads in the limestone block were alive, and,
+    curiously enough, one or two had actually increased in weight.
+    Thus, No. 5, which at the commencement of its captivity had
+    weighed 1185 grains, had increased to 1265 grains; but the
+    glass cover of No. 5's cell was found to be cracked. Insects
+    and air must therefore have obtained admittance and have
+    afforded nourishment to the imprisoned toad; this supposition
+    being rendered the more likely by the discovery that in one of
+    the cells, the covers of which were also cracked and the tenant
+    of which was dead, numerous insects were found. No. 9, weighing
+    originally 988 grains, had <span class="pagenum"><a name=
+    "page169"
+       id="page169"></a>[pg 169]</span> increased during its
+       incarceration to 1116 grains; but No. 1, which in the year
+       1825 had weighed 924 grains, was found in December, 1826, to
+       have decreased to 698 grains; and No. 11, originally
+       weighing 936 grains, had likewise disagreed with the
+       imprisonment, weighing only 652 grains when examined in
+       1826.</p>
+
+    <p>At the period when the blocks of stone were thus prepared,
+    four toads were pinned up in holes five inches deep and three
+    inches in diameter, cut in the stem of an apple-tree; the
+    holes being firmly plugged with tightly fitting wooden plugs.
+    These four toads were found to be dead when examined along with
+    the others in 1826; and of four others enclosed in basins made
+    of plaster of Paris, and which were also buried in Dr.
+    Buckland's garden, two were found to be dead at the end of a
+    year, their comrades being alive, but looking starved and
+    meagre. The toads which were found alive in the limestone block
+    in December, 1826, were again immured and buried, but were
+    found to be dead, without leaving a single survivor, at the end
+    of the second year of their imprisonment.</p>
+
+    <p>These experiments may fairly be said to prove two points.
+    They firstly show that under circumstances even of a favorable
+    kind when compared with the condition popularly believed
+    in&mdash;namely, that of being enclosed in a <i>solid</i>
+    rock&mdash;the limit of the toad's life may be assumed to be
+    within two years; this period being no doubt capable of being
+    extended when the animal gains a slight advantage, exemplified
+    by the admission of air and insect-food. Secondly, we may
+    reasonably argue that these experiments show that toads when
+    rigorously treated, like other animals, <span class=
+    "pagenum"><a id="page170"></a>[pg 170]</span> become starved and meagre,
+       and by no means resemble the lively, well-fed animals
+       reported as having emerged from an imprisonment extending,
+       in popular estimation, through periods of inconceivable
+       duration.</p>
+
+    <p>These tales are, in short, as devoid of actual foundation as
+    are the modern beliefs in the venomous properties of the toad,
+    or the ancient beliefs in the occult and mystic powers of
+    various parts of its frame when used in incantations.
+    Shakespeare, whilst attributing to the toad venomous qualities,
+    has yet immortalized it in his famous simile by crediting it
+    with the possession of a "precious jewel." But even in the
+    latter case the animal gets but scant justice; for science
+    strips it of its poetical reputation, and in this, as in other
+    respects, shows it, despite fable and myth, to be zoölogically
+    an interesting, but otherwise a commonplace member of the
+    animal series.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/170.png"><img width="500"
+             src="images/170.png"
+             alt="Toads."></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="page171"></a>[pg 171]</span>
+
+    <h2>ON A PIECE OF CHALK</h2>
+
+    <h3><i>A LECTURE TO WORKING MEN</i>.</h3>
+
+    <h4>(Delivered in England.)</h4>
+
+    <h3><span class="sc">By</span> T.H. HUXLEY.</h3>
+    <hr class="short">
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/171.png"><img width="300"
+             src="images/171.png"
+             alt="A CHALK CLIFF."></a><br>
+        A CHALK CLIFF.
+    </div>
+
+    <p>If a well were to be sunk at our feet in the midst of the
+    city of Norwich, the diggers would very soon find themselves at
+    work in that white substance almost too soft to be called rock,
+    with which we are all familiar as "chalk."</p>
+
+    <p>Not only here, but over the whole county of Norfolk, the
+    well-sinker might carry his shaft down many hundred feet
+    without coming to the end of the chalk; and, on the sea-coast,
+    where the waves have pared away the face of the land which
+    breasts them, the scarped faces of the high cliffs are often
+    wholly formed of the same material. Northward, the chalk may be
+    followed as far as Yorkshire; on the <span class=
+    "pagenum"><a id="page172"></a>[pg 172]</span> south coast it appears
+       abruptly in the picturesque western bays of Dorset, and
+       breaks into the Needles of the Isle of Wight; while on the
+       shores of Kent it supplies that long line of white cliffs to
+       which England owes her name of Albion.</p>
+
+    <p>Were the thin soil which covers it all washed away, a curved
+    band of white chalk, here broader, and there narrower, might be
+    followed diagonally across England from Lulworth in Dorset, to
+    Flamborough Head in Yorkshire&mdash;a distance of over two
+    hundred and eighty miles as the crow flies.</p>
+
+    <p>From this band to the North Sea, on the east, and the
+    Channel, on the south, the chalk is largely hidden by other
+    deposits; but, except in the Weald of Kent and Sussex, it
+    enters into the very foundation of all the south-eastern
+    counties.</p>
+
+    <p>Attaining, as it does in some places, a thickness of more
+    than a thousand feet, the English chalk must be admitted to be
+    a mass of considerable magnitude. Nevertheless, it covers but
+    an insignificant portion of the whole area occupied by the
+    chalk formation of the globe, which has precisely the same
+    general character as ours, and is found in detached patches,
+    some less, and others more extensive, than the English.</p>
+
+    <p>Chalk occurs in north-west Ireland; it stretches over a
+    large part of France&mdash;the chalk which underlies Paris
+    being, in fact, a continuation of that of the London basin; it
+    runs through Denmark and Central Europe, and extends southward
+    to North Africa; while eastward, it appears in the Crimea and
+    in Syria, and may be traced as far as the shores of the Sea of
+    Aral, in Central Asia.</p><span class="pagenum"><a name=
+    "page173"
+       id="page173"></a>[pg 173]</span>
+
+    <p>If all the points at which true chalk occurs were
+    circumscribed, they would lie within an irregular oval about
+    three thousand miles in long diameter&mdash;the area of which
+    would be as great as that of Europe, and would many times
+    exceed that of the largest existing inland sea&mdash;the
+    Mediterranean.</p>
+
+    <p>Thus the chalk is no unimportant element in the masonry of
+    the earth's crust, and it impresses a peculiar stamp, varying
+    with the conditions to which it is exposed, on the scenery of
+    the districts in which it occurs. The undulating downs and
+    rounded coombs, covered with sweet-grassed turf, of our inland
+    chalk country, have a peacefully domestic and mutton-suggesting
+    prettiness, but can hardly be called either grand or beautiful.
+    But on our southern coasts, the wall-sided cliffs, many hundred
+    feet high, with vast needles and pinnacles standing out in the
+    sea, sharp and solitary enough to serve as perches for the wary
+    cormorant, confer a wonderful beauty and grandeur upon the
+    chalk headlands. And in the East, chalk has its share in the
+    formation of some of the most venerable of mountain ranges,
+    such as the Lebanon.</p>
+    <hr>
+
+    <p>What is this wide-spread component of the surface of the
+    earth? and whence did it come?</p>
+
+    <p>You may think this no very hopeful inquiry. You may not
+    unnaturally suppose that the attempt to solve such problems as
+    these can lead to no result, save that of entangling the
+    inquirer in vague speculations, incapable of refutation and of
+    verification.</p>
+
+    <p>If such were really the case, I should have selected some
+    other subject than a "piece of chalk" for my <span class=
+    "pagenum"><a id="page174"></a>[pg 174]</span> discourse. But, in truth,
+       after much deliberation, I have been unable to think of any
+       topic which would so well enable me to lead you to see how
+       solid is the foundation upon which some of the most
+       startling conclusions of physical science rest.</p>
+
+    <p>A great chapter of the history of the world is written in
+    the chalk. Few passages in the history of man can be supported
+    by such an overwhelming mass of direct and indirect evidence as
+    that which testifies to the truth of the fragment of the
+    history of the globe, which I hope to enable you to read, with
+    your own eyes, to-night.</p>
+
+    <div class="figleft"
+         style="width:400px;">
+        <a href="images/174.png"><img width="400"
+             src="images/174.png"
+             alt="MICROSCOPIC SECTION OF CHALK."></a><br>
+        MICROSCOPIC SECTION OF CHALK.<br>
+        (Magnified nearly 300 times.)<br>
+        1. Textularia. 2. Globigerina. 3. Rotalia. 4. Coccoliths.
+    </div>
+
+    <p>Let me add, that few chapters of human history have a more
+    profound significance for ourselves. I weigh my words well when
+    I assert, that the man who should know the true history of the
+    bit of chalk which every carpenter carries about in his
+    breeches' pocket, though ignorant of all other history, is
+    likely, if he will think his knowledge out to its ultimate
+    results, to have a truer, and therefore a better, conception of
+    this wonderful universe, and of man's relation to it, than the
+    most learned student who <span class="pagenum"><a name=
+    "page175"
+       id="page175"></a>[pg 175]</span> is deep-read in the records
+       of humanity and ignorant of those of nature.</p>
+
+    <p>The language of the chalk is not hard to learn, not nearly
+    so hard as Latin, if you only want to get at the broad features
+    of the story it has to tell; and I propose that we now set to
+    work to spell that story out together.</p>
+
+    <p>We all know that if we "burn" chalk, the result is
+    quicklime. Chalk, in fact, is a compound of carbonic acid gas
+    and lime; and when you make it very hot, the carbonic acid
+    flies away and the lime is left.</p>
+
+    <p>By this method of procedure we see the lime, but we do not
+    see the carbonic acid. If, on the other hand, you were to
+    powder a little chalk and drop it into a good deal of strong
+    vinegar, there would be a great bubbling and fizzing, and,
+    finally, a clear liquid, in which no sign of chalk would
+    appear. Here you see the carbonic acid in the bubbles; the
+    lime, dissolved in the vinegar, vanishes from sight. There are
+    a great many other ways of showing that chalk is essentially
+    nothing but carbonic acid and quicklime. Chemists enunciate the
+    result of all the experiments which prove this, by stating that
+    chalk is almost wholly composed of "carbonate of lime."</p>
+
+    <p>It is desirable for us to start from the knowledge of this
+    fact, though it may not seem to help us very far toward what we
+    seek. For carbonate of lime is a widely-spread substance, and
+    is met with under very various conditions. All sorts of
+    limestones are composed of more or less pure carbonate of lime.
+    The crust which is often deposited by waters which have drained
+    through limestone rocks, in the form of what are called
+    stalagmites and stalactites, is carbonate of <span class=
+    "pagenum"><a id="page176"></a>[pg 176]</span> lime. Or, to take a more
+       familiar example, the fur on the inside of a tea-kettle is
+       carbonate of lime; and, for anything chemistry tells us to
+       the contrary, the chalk might be a kind of gigantic fur upon
+       the bottom of the earth-kettle, which is kept pretty hot
+       below.</p>
+
+    <p>Let us try another method of making the chalk tell us its
+    own history. To the unassisted eye chalk looks simply like a
+    very loose and open kind of stone. But it is possible to grind
+    a slice of chalk down so thin that you can see through
+    it&mdash;until it is thin enough, in fact, to be examined with
+    any magnifying power that may be thought desirable. A thin
+    slice of the fur of a kettle might be made in the same way. If
+    it were examined microscopically, it would show itself to be a
+    more or less distinctly laminated mineral substance, and
+    nothing more.</p>
+
+    <p>But the slice of chalk presents a totally different
+    appearance when placed under the microscope. The general mass
+    of it is made up of very minute granules; but, imbedded in this
+    matrix, are innumerable bodies, some smaller and some larger,
+    but, on a rough average, not more than a hundredth of an inch
+    in diameter, having a well-defined shape and structure. A cubic
+    inch of some specimens of chalk may contain hundreds of
+    thousands of these bodies, compacted together with incalculable
+    millions of the granules.</p>
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/176.png"><img width="250"
+             src="images/176.png"
+             alt="CHALK."></a><br>
+        CHALK.<br>
+        (Magnified nearly 100 diameters.)
+    </div>
+
+    <p>The examination of a transparent slice gives a good notion
+    of the manner in which the components of the <span class=
+    "pagenum"><a id="page177"></a>[pg 177]</span> chalk are arranged, and of
+       their relative proportions. But, by rubbing up some chalk
+       with a brush in water and then pouring off the milky fluid,
+       so as to obtain sediments of different degrees of fineness,
+       the granules and the minute rounded bodies may be pretty
+       well separated from one another, and submitted to
+       microscopic examination, either as opaque or as transparent
+       objects. By combining the views obtained in these various
+       methods, each of the rounded bodies may be proved to be a
+       beautifully-constructed calcareous fabric, made up of a
+       number of chambers, communicating freely with one another.
+       The chambered bodies are of various forms. One of the
+       commonest is something like a badly-grown raspberry, being
+       formed of a number of nearly globular chambers of different
+       sizes congregated together. It is called Globigerina, and
+       some specimens of chalk consist of little else than
+       Globigerinæ and granules.</p>
+
+    <div class="figright"
+         style="width:150px;">
+        <a href="images/177.png"><img width="150"
+             src="images/177.png"
+             alt="GLOBIGERINA."></a><br>
+        GLOBIGERINA.
+    </div>
+
+    <p>Let us fix our attention upon the Globigerina. It is the
+    spoor of the game we are tracking. If we can learn what it is
+    and what are the conditions of its existence, we shall see our
+    way to the origin and past history of the chalk.</p>
+
+    <p>A suggestion which may naturally enough present itself is,
+    that these curious bodies are the result of some process of
+    aggregation which has taken place in the carbonate of lime;
+    that, just as in winter, the rime on our windows simulates the
+    most delicate and elegantly arborescent foliage&mdash;proving
+    that the mere mineral matter may, under certain conditions,
+    assume the outward form of organic bodies&mdash;so this mineral
+    <span class="pagenum"><a id="page178"></a>[pg 178]</span> substance, carbonate of
+       lime, hidden away in the bowels of the earth, has taken the
+       shape of these chambered bodies. I am not raising a merely
+       fanciful and unreal objection. Very learned men, in former
+       days, have even entertained the notion that all the formed
+       things found in rocks are of this nature; and if no such
+       conception is at present held to be admissible, it is
+       because long and varied experience has now shown that
+       mineral matter never does assume the form and structure we
+       find in fossils. If anyone were to try to persuade you that
+       an oyster-shell (which is also chiefly composed of carbonate
+       of lime) had crystallized out of sea-water, I suppose you
+       would laugh at the absurdity. Your laughter would be
+       justified by the fact that all experience tends to show that
+       oyster-shells are formed by the agency of oysters, and in no
+       other way. And if there were no better reasons, we should be
+       justified, on like grounds, in believing that Globigerina is
+       not the product of anything but vital activity.</p>
+
+    <p>Happily, however, better evidence in proof of the organic
+    nature of the Globigerinæ than that of analogy is forthcoming.
+    It so happens that calcareous skeletons, exactly similar to the
+    Globigerinæ of the chalk, are being formed, at the present
+    moment, by minute living creatures, which flourish in
+    multitudes, literally more numerous than the sands of the
+    sea-shore, over a large extent of that part of the earth's
+    surface which is covered by the ocean.</p>
+
+    <p>The history of the discovery of these living Globigerinæ,
+    and of the part which they play in rock-building, is singular
+    enough. It is a discovery which, like others of no less
+    scientific importance, has arisen, <span class=
+    "pagenum"><a id="page179"></a>[pg 179]</span> incidentally, out of work
+       devoted to very different and exceedingly practical
+       interests.</p>
+
+    <p>When men first took to the sea, they speedily learned to
+    look out for shoals and rocks; and the more the burthen of
+    their ships increased, the more imperatively necessary it
+    became for sailors to ascertain with precision the depth of the
+    waters they traversed. Out of this necessity grew the use of
+    the lead and sounding-line; and, ultimately, marine-surveying,
+    which is the recording of the form of coasts and of the depth
+    of the sea, as ascertained by the sounding-lead, upon
+    charts.</p>
+
+    <p>At the same time, it became desirable to ascertain and to
+    indicate the nature of the sea-bottom, since this circumstance
+    greatly affects its goodness as holding ground for anchors.
+    Some ingenious tar, whose name deserves a better fate than the
+    oblivion into which it has fallen, attained this object by
+    "arming" the bottom of the lead with a lump of grease, to which
+    more or less of the sand or mud, or broken shells, as the case
+    might be, adhered, and was brought to the surface. But, however
+    well adapted such an apparatus might be for rough nautical
+    purposes, scientific accuracy could not be expected from the
+    armed lead, and to remedy its defects (especially when applied
+    to sounding in great depths) Lieutenant Brooke, of the American
+    Navy, some years ago invented a most ingenious machine, by
+    which a considerable portion of the superficial layer of the
+    sea-bottom can be scooped out and brought up, from any depth to
+    which the lead descends.</p>
+
+    <p>In 1853, Lieutenant Brooke obtained mud from the bottom of
+    the North Atlantic, between Newfoundland and the Azores, at a
+    depth of more than ten thousand <span class=
+       "pagenum"><a id="page180"></a>[pg 180]</span> feet, or two miles, by the
+       help of this sounding apparatus. The specimens were sent for
+       examination to Ehrenberg of Berlin, and to Bailey of West
+       Point, and those able microscopists found that this deep-sea
+       mud was almost entirely composed of the skeletons of living
+       organisms&mdash;the greater proportion of these being just
+       like the Globigerinæ already known to occur in chalk.</p>
+
+    <p>Thus far, the work had been carried on simply in the
+    interests of science, but Lieutenant Brooke's method of
+    sounding acquired a high commercial value, when the enterprise
+    of laying down the telegraph-cable between this country and the
+    United States was undertaken. For it became a matter of immense
+    importance to know, not only the depth of the sea over the
+    whole line, along which the cable was to be laid, but the exact
+    nature of the bottom, so as to guard against chances of cutting
+    or fraying the strands of that costly rope. The Admiralty
+    consequently ordered Captain Dayman, an old friend and shipmate
+    of mine, to ascertain the depth over the whole line of the
+    cable, and to bring back specimens of the bottom. In former
+    days, such a command as this might have sounded very much like
+    one of the impossible things which the young prince in the
+    Fairy Tales is ordered to do before he can obtain the hand of
+    the princess. However, in the months of June and July, 1857, my
+    friend performed the task assigned to him with great expedition
+    and precision, without, so far as I know, having met with any
+    reward of that kind. The specimens of Atlantic mud which he
+    procured were sent to me to be examined and reported upon.</p>
+
+    <p>The result of all these operations is, that we know
+    <span class="pagenum"><a id="page181"></a>[pg 181]</span> the contours and the nature
+       of the surface-soil covered by the North Atlantic, for a
+       distance of seventeen hundred miles from east to west, as
+       well as we know that of any part of the dry land.</p>
+
+    <p>It is a prodigious plain&mdash;one of the widest and most
+    even plains in the world. If the sea were drained off, you
+    might drive a wagon all the way from Valentia, on the west
+    coast of Ireland, to Trinity Bay in Newfoundland. And, except
+    upon one sharp incline about two hundred miles from Valentia, I
+    am not quite sure that it would even be necessary to put the
+    skid on, so gentle are the ascents and descents upon that long
+    route. From Valentia the road would lie down-hill for about two
+    hundred miles to the point at which the bottom is now covered
+    by seventeen hundred fathoms of sea-water. Then would come the
+    central plain, more than a thousand miles wide, the
+    inequalities of the surface of which would be hardly
+    perceptible, though the depth of water upon it now varies from
+    ten thousand to fifteen thousand feet; and there are places in
+    which Mont Blanc might be sunk without showing its peak above
+    water. Beyond this, the ascent on the American side commences,
+    and gradually leads, for about three hundred miles, to the
+    Newfoundland shore.</p>
+
+    <p>Almost the whole of the bottom of this central plain (which
+    extends for many hundred miles in a north and south direction)
+    is covered by a fine mud, which, when brought to the surface,
+    dries into a grayish white friable substance. You can write
+    with this on a black-board, if you are so inclined; and, to the
+    eye, it is quite like very soft, grayish chalk. Examined
+    chemically, it proves to be composed almost wholly of
+    <span class="pagenum"><a id="page182"></a>[pg 182]</span> carbonate of lime; and if
+       you make a section of it, in the same way as that of the
+       piece of chalk was made, and view it with the microscope, it
+       presents innumerable Globigerinæ embedded in a granular
+       matrix.</p>
+
+    <p>Thus this deep-sea mud is substantially chalk. I say
+    substantially, because there are a good many minor differences;
+    but as these have no bearing on the question immediately before
+    us&mdash;which is the nature of the Globigerinæ of the
+    chalk&mdash;it is unnecessary to speak of them.</p>
+
+    <p>Globigerinæ of every size, from the smallest to the largest,
+    are associated together in the Atlantic mud, and the chambers
+    of many are filled by a soft animal matter. This soft substance
+    is, in fact, the remains of the creature to which the
+    Globigerina shell, or rather skeleton, owes its
+    existence&mdash;and which is an animal of the simplest
+    imaginable description. It is, in fact, a mere particle of
+    living jelly, without defined parts of any kind&mdash;without a
+    mouth, nerves, muscles, or distinct organs, and only
+    manifesting its vitality to ordinary observation by thrusting
+    out and retracting from all parts of its surface long
+    filamentous processes, which serve for arms and legs. Yet this
+    amorphous particle, devoid of everything which, in the higher
+    animals, we call organs, is capable of feeding, growing, and
+    multiplying; of separating from the ocean the small proportion
+    of carbonate of lime which is dissolved in sea-water; and of
+    building up that substance into a skeleton for itself,
+    according to a pattern which can be imitated by no other known
+    agency.</p>
+
+    <p>The notion that animals can live and flourish in the sea, at
+    the vast depths from which apparently living <span class=
+    "pagenum"><a id="page183"></a>[pg 183]</span> Giobigerinæ have been
+       brought up, does not agree very well with our usual
+       conceptions respecting the conditions of animal life; and it
+       is not so absolutely impossible as it might at first sight
+       appear to be, that the Globigerinæ of the Atlantic
+       sea-bottom do not live and die where they are found.</p>
+
+    <div class="figright"
+         style="width:400px;">
+        <a href="images/183.png"><img width="400"
+             src="images/183.png"
+             alt=
+           "DIATOM OOZE DREDGED FROM A DEPTH OF 1950"></a><br>
+        DIATOM OOZE DREDGED FROM A DEPTH OF 1950 FEET.<br>
+        (Magnified nearly 300 diameters.)
+    </div>
+
+    <p>As I have mentioned, the soundings from the great Atlantic
+    plain are almost entirely made up of Globigerinæ, with the
+    granules which have been mentioned, and some few other
+    calcareous shells; but a small percentage of the chalky
+    mud&mdash;perhaps at most some five per cent of it&mdash;is of
+    a different nature, and consists of shells and skeletons
+    composed of silex, or pure flint. These siliceous bodies belong
+    partly to the lowly vegetable organisms which are called
+    Diatomaceæ, and partly to the minute and extremely simple
+    animals, termed Radiolaria. It is quite certain that these
+    creatures do not live at the bottom of the ocean, but at its
+    surface&mdash;where they may be obtained in prodigious numbers
+    by the use of a properly constructed net. Hence it follows that
+    these siliceous organisms, though they are not heavier than the
+    lightest dust, must have fallen, in some cases, through fifteen
+    thousand feet of water, before they reached their final
+    resting-place on the ocean floor. And, considering how
+    <span class="pagenum"><a id="page184"></a>[pg 184]</span> large a surface these
+       bodies expose in proportion to their weight, it is probable
+       that they occupy a great length of time in making their
+       burial journey from the surface of the Atlantic to the
+       bottom.</p>
+
+    <div class="figleft"
+         style="width:400px;">
+        <a href="images/184.png"><img width="400"
+             src="images/184.png"
+             alt="RADIOLARIA."></a><br>
+        RADIOLARIA.<br>
+        (<i>a.</i> Natural size. <i>b.</i> One-third natural size.)
+    </div>
+
+    <p>But if the Radiolaria and Diatoms are thus rained upon the
+    bottom of the sea, from the superficial layer of its waters in
+    which they pass their lives, it is obviously possible that the
+    Globigerinæ may be similarly derived; and if they were so, it
+    would be much more easy to understand how they obtain their
+    supply of food than it is at present. Nevertheless, the
+    positive and negative evidence all points the other way. The
+    skeletons of the full-grown, deep-sea Globigerinæ are so
+    remarkably solid and heavy in proportion to their surface as to
+    seem little fitted for floating; and, as a matter of fact, they
+    are not to be found along with the Diatoms and Radiolaria, in
+    the uppermost stratum of the open ocean.</p>
+
+    <p>It has been observed, again, that the abundance of
+    Globigerinæ, in proportion to other organisms of like kind,
+    increases with the depth of the sea; and that deep-water
+    Globigerinæ are larger than those which live in the shallower
+    parts of the sea; and such facts negative the supposition that
+    these organisms have been swept by currents from the shallows
+    into the deeps of the Atlantic.</p><span class="pagenum"><a id="page185"></a>[pg 185]</span>
+
+    <p>It therefore seems to be hardly doubtful that these
+    wonderful creatures live and die at the depths in which they
+    are found.<a id="footnotetag2"></a><a href="#footnote2"><sup>2</sup></a></p>
+
+    <p>However, the important points for us are, that the living
+    Globigerinæ are exclusively marine animals, the skeletons of
+    which abound at the bottom of deep seas; and that there is not
+    a shadow of reason for believing that the habits of the
+    Globigerinæ of the chalk differed from those of the existing
+    species. But if this be true, there is no escaping the
+    conclusion that the chalk itself is the dried mud of an ancient
+    deep sea.</p>
+
+    <p>In working over the soundings collected by Captain Dayman, I
+    was surprised to find that many of what I have called the
+    "granules" of that mud were not, as one might have been tempted
+    to think at first, the mere powder and waste of Globigerinæ,
+    but that they had a definite form and size. I termed these
+    bodies "<i>coccoliths</i>" and doubted their organic nature.
+    Dr. Wallich verified my observation, and added the interesting
+    discovery that, not unfrequently, bodies similar to these
+    "coccoliths" were aggregated together into spheroids, which he
+    termed "<i>coccospheres</i>." So far as we knew, these bodies,
+    the nature of which is extremely <span class=
+       "pagenum"><a id="page186"></a>[pg 186]</span> puzzling and problematical,
+       were peculiar to the Atlantic soundings.</p>
+
+    <p>But, a few years ago, Mr. Sorby, in making a careful
+    examination of the chalk by means of thin sections and
+    otherwise, observed, as Ehrenberg had done before him, that
+    much of its granular basis possesses a definite form. Comparing
+    these formed particles with those in the Atlantic soundings, he
+    found the two to be identical; and thus proved that the chalk,
+    like the soundings, contains these mysterious coccoliths and
+    coccospheres. Here was a further and a most interesting
+    confirmation, from internal evidence, of the essential identity
+    of the chalk with modern deep-sea mud. Globigerinæ, coccoliths,
+    and coccospheres are found as the chief constituents of both,
+    and testify to the general similarity of the conditions under
+    which both have been formed.<a id="footnotetag3"></a><a href="#footnote3"><sup>3</sup></a></p>
+
+    <p>The evidence furnished by the hewing, facing, and
+    superposition of the stones of the Pyramids, that these
+    structures were built by men, has no greater weight than the
+    evidence that the chalk was built by Globigerinæ; and the
+    belief that those ancient pyramid-builders were terrestrial and
+    air-breathing creatures like ourselves, is not better based
+    than the conviction that the chalk-makers lived in the sea.</p>
+
+    <p>But as our belief in the building of the Pyramids by men is
+    not only grounded on the internal evidence afforded by these
+    structures, but gathers strength from multitudinous collateral
+    proofs, and is clinched by the <span class=
+       "pagenum"><a id="page187"></a>[pg 187]</span> total absence of any reason
+       for a contrary belief; so the evidence drawn from the
+       Globigerinæ that the chalk is an ancient sea-bottom, is
+       fortified by innumerable independent lines of evidence; and
+       our belief in the truth of the conclusion to which all
+       positive testimony tends, receives the like negative
+       justification from the fact that no other hypothesis has a
+       shadow of foundation.</p>
+
+    <p>It may be worth while briefly to consider a few of these
+    collateral proofs that the chalk was deposited at the bottom of
+    the sea.</p>
+
+    <p>The great mass of the chalk is composed, as we have seen, of
+    the skeletons of Globigerinæ, and other simple organisms,
+    imbedded in granular matter. Here and there, however, this
+    hardened mud of the ancient sea reveals the remains of higher
+    animals which have lived and died, and left their hard parts in
+    the mud, just as the oysters die and leave their shells behind
+    them, in the mud of the present seas.</p>
+
+    <div class="figright"
+         style="width:300px;">
+        <a href="images/187.png"><img width="300"
+             src="images/187.png"
+             alt="UPPER SILURIAN CORALS AND CRUSTACEANS."></a><br>
+        UPPER SILURIAN CORALS AND CRUSTACEANS.
+    </div>
+
+    <p>There are, at the present day, certain groups of animals
+    which are never found in fresh waters, being unable to live
+    anywhere but in the sea. Such are the corals; those corallines
+    which are called Polyzoa; those creatures which fabricate the
+    lamp-shells, and are called Brachiopoda; the pearly Nautilus,
+    and all animals allied to it; and all the forms of sea-urchins
+    and star-fishes.</p><span class="pagenum"><a id="page188"></a>[pg 188]</span>
+
+    <p>Not only are all these creatures confined to salt water at
+    the present day, but, so far as our records of the past go, the
+    conditions of their existence have been the same: hence, their
+    occurrence in any deposit is as strong evidence as can be
+    obtained, that that deposit was formed in the sea. Now the
+    remains of animals of all the kinds which have been enumerated
+    occur in the chalk, in greater or less abundance; while not one
+    of those forms of shell-fish which are characteristic of fresh
+    water has yet been observed in it.</p>
+
+    <p>When we consider that the remains of more than three
+    thousand distinct species of aquatic animals have been
+    discovered among the fossils of the chalk, that the great
+    majority of them are of such forms as are now met with only in
+    the sea, and that there is no reason to believe that any one of
+    them inhabited fresh water&mdash;the collateral evidence that
+    the chalk represents an ancient sea-bottom acquires as great
+    force as the proof derived from the nature of the chalk itself.
+    I think you will now allow that I did not overstate my case
+    when I asserted that we have as strong grounds for believing
+    that all the vast area of dry land at present occupied by the
+    chalk was once at the bottom of the sea, as we have for any
+    matter of history whatever; while there is no justification for
+    any other belief.</p>
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/188.png"><img width="250"
+             src="images/188.png"
+             alt="CRETACEOUS NAUTILUS."></a>CRETACEOUS NAUTILUS.
+    </div>
+
+    <p>No less certain is it that the time during which the
+    countries we now call southeast England, France, Germany,
+    Poland, Russia, Egypt, Arabia, Syria, were more
+          <span class="pagenum"><a id="page189"></a>[pg 189]</span> or less completely covered
+       by a deep sea, was of considerable duration.</p>
+
+    <p>We have already seen that the chalk is, in places, more than
+    a thousand feet thick. I think you will agree with me that it
+    must have taken some time for the skeletons of the animalcules
+    of a hundredth of an inch in diameter to heap up such a mass as
+    that. I have said that throughout the thickness of the chalk
+    the remains of other animals are scattered. These remains are
+    often in the most exquisite state of preservation. The valves
+    of the shell-fishes are commonly adherent; the long spines of
+    some of the sea-urchins, which would be detached by the
+    smallest jar, often remain in their places. In a word, it is
+    certain that these animals have lived and died when the place
+    which they now occupy was the surface of as much of the chalk
+    as had then been deposited; and that each has been covered up
+    by the layer of Globigerina mud, upon which the creatures
+    imbedded a little higher up have, in like manner, lived and
+    died. But some of these remains prove the existence of reptiles
+    of vast size in the chalk sea. These lived their time, and had
+    their ancestors and descendants, which assuredly implies time,
+    reptiles being of slow growth.</p>
+
+    <p>There is more curious evidence, again, that the process of
+    covering up, or, in other words, the deposit of Globigerina
+    skeletons, did not go on very fast. It is demonstrable that an
+    animal of the cretaceous sea might die, that its skeleton might
+    lie uncovered upon the sea-bottom long enough to lose all its
+    outward coverings and appendages by putrefaction; and that,
+    after this had happened, another animal might attach itself
+    <span class="pagenum"><a id="page190"></a>[pg 190]</span> to the dead and naked
+       skeleton, might grow to maturity, and might itself die
+       before the calcareous mud had buried the whole.</p>
+
+    <p>Cases of this kind are admirably described by Sir Charles
+    Lyell. He speaks of the frequency with which geologists find in
+    the chalk a fossilized sea-urchin to which is attached the
+    lower valve of a Crania. This is a kind of shell-fish, with a
+    shell composed of two pieces, of which, as in the oyster, one
+    is fixed and the other free.</p>
+
+    <p>"The upper valve is almost invariably wanting, though
+    occasionally found in a perfect state of preservation in the
+    white chalk at some distance. In this case, we see clearly that
+    the sea-urchin first lived from youth to age, then died and
+    lost its spines, which were carried away. Then the young Crania
+    adhered to the bared shell, grew and perished in its turn;
+    after which, the upper valve was separated from the lower,
+    before the Echinus became enveloped in chalky mud."</p>
+
+    <p>A specimen in the Museum of Practical Geology, in London,
+    still further prolongs the period which must have elapsed
+    between the death of the sea-urchin and its burial by the
+    Globigeringæ. For the outward face of the valve of a Crania,
+    which is attached to a sea-urchin (Micrastor), is itself
+    overrun by an incrusting coralline, which spreads thence over
+    more or less of the surface of the sea-urchin. It follows that,
+    after the upper valve of the Crania fell off, the surface of
+    the attached valve must have remained exposed long enough to
+    allow of the growth of the whole coralline, since corallines do
+    not live imbedded in the mud.</p>
+
+    <p>The progress of knowledge may, one day, enable us
+    <span class="pagenum"><a id="page191"></a>[pg 191]</span> to deduce from such facts
+       as these the maximum rate at which the chalk can have
+       accumulated, and thus to arrive at the minimum duration of
+       the chalk period. Suppose that the valve of the Crania upon
+       which a coralline has fixed itself in the way just described
+       is so attached to the sea-urchin that no part of it is more
+       than an inch above the face upon which the sea-urchin rests.
+       Then, as the coralline could not have fixed itself if the
+       Crania had been covered up with chalk-mud, and could not
+       have lived had itself been so covered, it follows, that an
+       inch of chalk mud could not have accumulated within the time
+       between the death and decay of the soft parts of the
+       sea-urchin and the growth of the coralline to the full size
+       which it has attained. If the decay of the soft parts of the
+       sea-urchin; the attachment, growth to maturity, and decay of
+       the Crania; and the subsequent attachment and growth of the
+       coralline, took a year (which is a low estimate enough), the
+       accumulation of the inch of chalk must have taken more than
+       a year: and the deposit of a thousand feet of chalk must,
+       consequently, have taken more than twelve thousand
+       years.</p>
+
+    <p>The foundation of all this calculation is, of course, a
+    knowledge of the length of time the Crania and the coralline
+    needed to attain their full size; and, on this head, precise
+    knowledge is at present wanting. But there are circumstances
+    which tend to show that nothing like an inch of chalk has
+    accumulated during the life of a Crania; and, on any probable
+    estimate of the length of that life, the chalk period must have
+    had a much longer duration than that thus roughly assigned to
+    it.</p><span class="pagenum"><a id="page192"></a>[pg 192]</span>
+
+    <p>Thus, not only is it certain that the chalk is the mud of an
+    ancient sea-bottom; but it is no less certain that the chalk
+    sea existed during an extremely long period, though we may not
+    be prepared to give a precise estimate of the length of that
+    period in years. The relative duration is clear, though the
+    absolute duration may not be definable. The attempt to affix
+    any precise date to the period at which the chalk sea began or
+    ended its existence, is baffled by difficulties of the same
+    kind. But the relative age of the cretaceous epoch may be
+    determined with as great ease and certainty as the long
+    duration of that epoch.</p>
+
+    <p>You will have heard of the interesting discoveries recently
+    made, in various parts of Western Europe, of flint implements,
+    obviously worked into shape by human hands, under circumstances
+    which show conclusively that man is a very ancient denizen of
+    these regions.</p>
+
+    <p>It has been proved that the old populations of Europe, whose
+    existence has been revealed to us in this way, consisted of
+    savages, such as the Esquimaux are now; that, in the country
+    which is now France, they hunted the reindeer, and were
+    familiar with the ways of the mammoth and the bison. The
+    physical geography of France was in those days different from
+    what it is now&mdash;the river Somme, for instance, having cut
+    its bed a hundred feet deeper between that time and this; and
+    it is probable that the climate was more like that of Canada or
+    Siberia than that of Western Europe.</p>
+
+    <p>The existence of these people is forgotten even in the
+    traditions of the oldest historical nations. The name
+    <span class="pagenum"><a id="page193"></a>[pg 193]</span> and fame of them had
+       utterly vanished until a few years back; and the amount of
+       physical change which has been effected since their day
+       renders it more than probable that, venerable as are some of
+       the historical nations, the workers of the chipped flints of
+       Hoxne or of Amiens are to them, as they are to us, in point
+       of antiquity.</p>
+
+    <p>But, if we assign to these hoar relics of long-vanished
+    generations of men the greatest age that can possibly be
+    claimed for them, they are not older than the drift, or boulder
+    clay, which, in comparison with the chalk, is but a very
+    juvenile deposit. You need go no further than your own seaboard
+    for evidence of this fact. At one of the most charming spots on
+    the coast of Norfolk, Cromer, you will see the boulder clay
+    forming a vast mass, which lies upon the chalk, and must
+    consequently have come into existence after it. Huge boulders
+    of chalk are, in fact, included in the clay, and have evidently
+    been brought to the position they now occupy by the same agency
+    as that which has planted blocks of syenite from Norway side by
+    side with them.</p>
+
+    <p>The chalk, then, is certainly older than the boulder clay.
+    If you ask how much, I will again take you no further than the
+    same spot upon your own coasts for evidence. I have spoken of
+    the boulder clay and drift as resting upon the chalk. That is
+    not strictly true. Interposed between the chalk and the drift
+    is a comparatively insignificant layer, containing vegetable
+    matter. But that layer tells a wonderful history. It is full of
+    stumps of trees standing as they grew. Fir-trees are there with
+    their cones, and hazel-bushes with their nuts; there stand the
+    stools of oak and yew trees, <span class="pagenum"><a name=
+    "page194"
+       id="page194"></a>[pg 194]</span> beeches and alders. Hence
+       this stratum is appropriately called the "forest-bed."</p>
+
+    <p>It is obvious that the chalk must have been upheaved and
+    converted into dry land before the timber trees could grow upon
+    it. As the bolls of some of these trees are from two to three
+    feet in diameter, it is no less clear that the dry land thus
+    formed remained in the same condition for long ages. And not
+    only do the remains of stately oaks and well-grown firs testify
+    to the duration of this condition of things, but additional
+    evidence to the same effect is afforded by the abundant remains
+    of elephants, rhinoceroses, hippopotamuses, and other great
+    wild beasts, which it has yielded to the zealous search of such
+    men as the Rev. Mr. Gunn.</p>
+
+    <p>When you look at such a collection as he has formed, and
+    bethink you that these elephantine bones did veritably carry
+    their owners about, and these great grinders crunch, in the
+    dark woods of which the forest-bed is now the only trace, it is
+    impossible not to feel that they are as good evidence of the
+    lapse of time as the annual rings of the tree-stumps.</p>
+
+    <p>Thus there is a writing upon the wall of cliffs at Cromer,
+    and whoso runs may read it. It tells us, with an authority
+    which cannot be impeached, that the ancient sea-bed of the
+    chalk sea was raised up, and remained dry land, until it was
+    covered with forest, stocked with the great game whose spoils
+    have rejoiced your geologists. How long it remained in that
+    condition cannot be said; but "the whirligig of time brought
+    its revenges" in those days as in these. That dry land, with
+    the bones and teeth of generations of <span class=
+    "pagenum"><a id="page195"></a>[pg 195]</span> long-lived elephants,
+       hidden away among the gnarled roots and dry leaves of its
+       ancient trees, sank gradually to the bottom of the icy sea,
+       which covered it with huge masses of drift and boulder clay.
+       Sea-beasts, such as the walrus, now restricted to the
+       extreme north, paddled about where birds had twittered among
+       the topmost twigs of the fir-trees. How long this state of
+       things endured we know not, but at length it came to an end.
+       The upheaved glacial mud hardened into the soil of modern
+       Norfolk. Forests grew once more, the wolf and the beaver
+       replaced the reindeer and the elephant; and at length what
+       we call the history of England dawned.</p>
+
+    <p>Thus you have, within the limits of your own county, proof
+    that the chalk can justly claim a very much greater antiquity
+    than even the oldest physical traces of mankind. But we may go
+    further and demonstrate, by evidence of the same authority as
+    that which testifies to the existence of the father of men,
+    that the chalk is vastly older than Adam himself.</p>
+
+    <p>The Book of Genesis informs us that Adam, immediately upon
+    his creation, and before the appearance of Eve, was placed in
+    the garden of Eden. The problem of the geographical position of
+    Eden has greatly vexed the spirits of the learned in such
+    matters, but there is one point respecting which, so far as I
+    know, no commentator has ever raised a doubt. This is, that of
+    the four rivers which are said to run out of it, Euphrates and
+    Hiddekel are identical with the rivers now known by the names
+    of Euphrates and Tigris.</p>
+
+    <p>But the whole country in which these mighty rivers take
+    their origin, and through which they run, is <span class=
+    "pagenum"><a id="page196"></a>[pg 196]</span> composed of rocks which are
+       either of the same age as the chalk, or of later date. So
+       that the chalk must not only have been formed, but, after
+       its formation, the time required for the deposit of these
+       later rocks, and for their upheaval into dry land, must have
+       elapsed, before the smallest brook which feeds the swift
+       stream of "the great river, the river of Babylon," began to
+       flow.</p>
+    <hr>
+
+    <p>Thus, evidence which cannot be rebutted, and which need not
+    be strengthened, though if time permitted I might indefinitely
+    increase its quantity, compels you to believe that the earth,
+    from the time of the chalk to the present day, has been the
+    theatre of a series of changes as vast in their amount as they
+    were slow in their progress. The area on which we stand has
+    been first sea and then land, for at least four alternations;
+    and has remained in each of these conditions for a period of
+    great length.</p>
+
+    <p>Nor have these wonderful metamorphoses of sea into land, and
+    of land into sea, been confined to one corner of England.
+    During the chalk period, or "cretaceous epoch," not one of the
+    present great physical features of the globe was in existence.
+    Our great mountain ranges, Pyrenees, Alps, Himalayas, Andes,
+    have all been upheaved since the chalk was deposited, and the
+    cretaceous sea flowed over the sites of Sinai and Ararat.</p>
+
+    <p>All this is certain, because rocks of cretaceous or still
+    later date have shared in the elevatory movements which gave
+    rise to these mountain chains; and may be found perched up, in
+    some cases, many thousand feet <span class=
+       "pagenum"><a id="page197"></a>[pg 197]</span> high upon their flanks. And
+       evidence of equal cogency demonstrates that, though in
+       Norfolk the forest-bed rests directly upon the chalk, yet it
+       does so, not because the period at which the forest grew
+       immediately followed that at which the chalk was formed, but
+       because an immense lapse of time, represented elsewhere by
+       thousands of feet of rock, is not indicated at Cromer.</p>
+
+    <p>I must ask you to believe that there is no less conclusive
+    proof that a still more prolonged succession of similar changes
+    occurred before the chalk was deposited. Nor have we any reason
+    to think that the first term in the series of these changes is
+    known. The oldest sea-beds preserved to us are sands, and mud,
+    and pebbles, the wear and tear of rocks which were formed in
+    still older oceans.</p>
+
+    <p>But, great as is the magnitude of these physical changes of
+    the world, they have been accompanied by a no less striking
+    series of modifications in its living inhabitants.</p>
+
+    <p>All the great classes of animals, beasts of the field, fowls
+    of the air, creeping things, and things which dwell in the
+    waters, flourished upon the globe long ages before the chalk
+    was deposited. Very few, however, if any, of these ancient
+    forms of animal life were identical with those which now live.
+    Certainly not one of the higher animals was of the same species
+    as any of those now in existence. The beasts of the field, in
+    the days before the chalk, were not our beasts of the field,
+    nor the fowls of the air such as those which the eye of man has
+    seen flying, unless his antiquity dates infinitely further back
+    than we at present surmise. If we could <span class=
+    "pagenum"><a id="page198"></a>[pg 198]</span> be carried back into those
+       times, we should be as one suddenly set down in Australia
+       before it was colonized. We should see mammals, birds,
+       reptiles, fishes, insects, snails, and the like, clearly
+       recognizable as such, and yet not one of them would be just
+       the same as those with which we are familiar, and many would
+       be extremely different.</p>
+
+    <p>From that time to the present, the population of the world
+    has undergone slow and gradual, but incessant, changes. There
+    has been no grand catastrophe&mdash;no destroyer has swept away
+    the forms of life of one period, and replaced them by a totally
+    new creation; but one species has vanished and another has
+    taken its place; creatures of one type of structure have
+    diminished, those of another have increased, as time has passed
+    on. And thus, while the differences between the living
+    creatures of the time before the chalk and those of the present
+    day appear startling, if placed side by side, we are led from
+    one to the other by the most gradual progress, if we follow the
+    course of Nature through the whole series of those relics of
+    her operations which she has left behind.</p>
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/198.png"><img width="200"
+             src="images/198.png"
+             alt="SKELETON OF THE PTERODACTYL."></a><br>
+        SKELETON OF THE PTERODACTYL.
+    </div>
+
+    <p>And it is by the population of the chalk sea that the
+    ancient and the modern inhabitants of the world are most
+    completely connected. The groups which are dying out flourish,
+    side by side, with the groups which are now the dominant forms
+    of life.</p>
+
+    <p>Thus the chalk contains remains of those flying and
+    <span class="pagenum"><a id="page199"></a>[pg 199]</span> swimming reptiles, the
+       pterodactyl, the ichthyosaurus, and the plesiosaurus, which
+       are found in no later deposits, but abounded in preceding
+       ages. The chambered shells called ammonites and belemnites,
+       which are so characteristic of the period preceding the
+       cretaceous, in like manner die with it.</p>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/199-1.png"><img width="600"
+             src="images/199-1.png"
+             alt="THE SKELETON OF THE ICHTHYOSAURUS."></a><br>
+        THE SKELETON OF THE ICHTHYOSAURUS.
+    </div>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/199-2.png"><img width="600"
+             src="images/199-2.png"
+             alt="THE SKELETON OF THE PLESIOSAURUS."></a><br>
+        THE SKELETON OF THE PLESIOSAURUS.
+    </div>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/199-3.png"><img width="600"
+             src="images/199-3.png"
+             alt="AMMONITES."></a><br>
+        AMMONITES.
+    </div>
+
+    <p>But, among these fading remainders of a previous state of
+    things, are some very modern forms of life, looking like Yankee
+    peddlers among a tribe of red Indians. Crocodiles of modern
+    type appear; bony fishes, many of them very similar to existing
+    species, almost supplant the forms of fish which predominate in
+    more ancient seas; and many kinds of living shell-fish
+    <span class="pagenum"><a id="page200"></a>[pg 200]</span> first become known to us in
+       the chalk. The vegetation acquires a modern aspect. A few
+       living animals are not even distinguishable as species from
+       those which existed at that remote epoch. The Globigerina of
+       the present day, for example, is not different specifically
+       from that of the chalk; and the same may be said of many
+       other Foraminifera. I think it probable that critical and
+       unprejudiced examination will show that more than one
+       species of much higher animals have had a similar longevity;
+       but the only example which I can at present give confidently
+       is the snake's-head lamp-shell (<i>Terebratulina caput
+       serpentis</i>), which lives in our English seas and abounded
+       (as <i>Terebratulina striata</i> of authors) in the
+       chalk.</p>
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/200-1.png"><img width="200"
+             src="images/200-1.png"
+             alt="BELEMNITES."></a><br>
+        BELEMNITES.
+    </div>
+
+    <div class="figright"
+         style="width:200px;">
+        <a href="images/200-2.png"><img width="200"
+             src="images/200-2.png"
+             alt="TEREBRATULINA."></a><br>
+        TEREBRATULINA.
+    </div>
+
+    <p>The longest line of human ancestry must hide its diminished
+    head before the pedigree of this insignificant shell-fish. We
+    Englishmen are proud to have an ancestor who was present at the
+    Battle of Hastings. The ancestors of <i>Terebratulina caput
+    serpentis</i> may have been present at a battle of
+    Ichthyosauria in that part of the sea which, when the chalk was
+    forming, flowed over the site of Hastings. While all around has
+    changed, this Terebratulina has peacefully propagated its
+    species from generation to generation, and stands to this day
+    as a living testimony to the <span class="pagenum"><a name=
+    "page201"
+       id="page201"></a>[pg 201]</span> continuity of the present
+       with the past history of the globe.</p>
+    <hr>
+
+    <p>Up to this moment I have stated, so far as I know, nothing
+    but well-authenticated facts, and the immediate conclusions
+    which they force upon the mind.</p>
+
+    <p>But the mind is so constituted that it does not willingly
+    rest in facts and immediate causes, but seeks always after a
+    knowledge of the remoter links in the chain of causation.</p>
+
+    <p>Taking the many changes of any given spot of the earth's
+    surface, from sea to land, and from land to sea, as an
+    established fact, we cannot refrain from asking ourselves how
+    these changes have occurred. And when we have explained
+    them&mdash;as they must be explained&mdash;by the alternate
+    slow movements of elevation and depression which have affected
+    the crusts of the earth, we go still further back, and ask, Why
+    these movements?</p>
+
+    <p>I am not certain that any one can give you a satisfactory
+    answer to that question. Assuredly I cannot. All that can be
+    said for certain is, that such movements are part of the
+    ordinary course of nature, inasmuch as they are going on at the
+    present time. Direct proof may be given, that some parts of the
+    land of the northern hemisphere are at this moment insensibly
+    rising and others insensibly sinking; and there is indirect but
+    perfectly satisfactory proof, that an enormous area now covered
+    by the Pacific has been deepened thousands of feet since the
+    present inhabitants of that sea came into existence.</p>
+
+    <p>Thus there is not a shadow of a reason for believing
+    <span class="pagenum"><a id="page202"></a>[pg 202]</span> that the physical changes
+       of the globe, in past times, have been effected by other
+       than natural causes.</p>
+
+    <p>Is there any more reason for believing that the concomitant
+    modifications in the forms of the living inhabitants of the
+    globe have been brought about in any other ways?</p>
+
+    <p>Before attempting to answer this question, let us try to
+    form a distinct mental picture of what has happened in some
+    special case.</p>
+
+    <p>The crocodiles are animals which, as a group, have a very
+    vast antiquity. They abounded ages before the chalk was
+    deposited; they throng the rivers in warm climates at the
+    present day. There is a difference in the form of the joints of
+    the backbone, and in some minor particulars, between the
+    crocodiles of the present epoch and those which lived before
+    the chalk; but, in the cretaceous epoch, as I have already
+    mentioned, the crocodiles had assumed the modern type of
+    structure. Notwithstanding this, the crocodiles of the chalk
+    are not identically the same as those which lived in the times
+    called "older tertiary," which succeeded the cretaceous epoch;
+    and the crocodiles of the older tertiaries are not identical
+    with those of the newer tertiaries, nor are these identical
+    with existing forms. I leave open the question whether
+    particular species may have lived on from epoch to epoch. But
+    each epoch has had its peculiar crocodiles; though all, since
+    the chalk, have belonged to the modern type, and differ simply
+    in their proportions and in such structural particulars as are
+    discernible only to trained eyes.</p>
+
+    <p>How is the existence of this long succession of different
+    species of crocodiles to be accounted
+          for?</p><span class="pagenum"><a id="page203"></a>[pg 203]</span>
+
+    <p>Only two suppositions seem to be open to us&mdash;either
+    each species of crocodile has been specially created, or it has
+    arisen out of some pre-existing form by the operation of
+    natural causes.</p>
+
+    <p>Choose your hypothesis; I have chosen mine. I can find no
+    warranty for believing in the distinct creation of a score of
+    successive species of crocodiles in the course of countless
+    ages of time. Science gives no countenance to such a wild
+    fancy; nor can even the perverse ingenuity of a commentator
+    pretend to discover this sense, in the simple words in which
+    the writer of Genesis records the proceeding of the fifth and
+    sixth days of the Creation.</p>
+
+    <p>On the other hand, I see no good reason for doubting the
+    necessary alternative, that all these varied species have been
+    evolved from pre-existing crocodilian forms by the operation of
+    causes as completely a part of the common order of nature as
+    those which have effected the changes of the inorganic
+    world.</p>
+
+    <p>Few will venture to affirm that the reasoning which applies
+    to crocodiles loses its force among other animals or among
+    plants. If one series of species has come into existence by the
+    operation of natural causes, it seems folly to deny that all
+    may have arisen in the same way.</p>
+    <hr>
+
+    <p>A small beginning has led us to a great ending. If I were to
+    put the bit of chalk with which we started into the hot but
+    obscure flame of burning hydrogen, it would presently shine
+    like the sun. It seems to me that this physical metamorphosis
+    is no false image of what has been the result of our subjecting
+    it to a jet <span class="pagenum"><a id="page204"></a>[pg 204]</span> of fervent, though nowise
+       brilliant, thought to-night. It has become luminous, and its
+       clear rays, penetrating the abyss of the remote past, have
+       brought within our ken some stages of the evolution of the
+       earth. And in the shifting "without haste, but without rest"
+       of the land and sea, as in the endless variation of the
+       forms assumed by living beings, we have observed nothing but
+       the natural product of the forces originally possessed by
+       the substance of the universe.</p>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/204.png"><img width="400"
+             src="images/204.png"
+             alt="Cliffs above the sea."></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="page205"></a>[pg 205]</span>
+
+    <h2>A BIT OF SPONGE</h2>
+
+    <h4>(Written on Scotland.)</h4>
+
+    <h4>(<span class="sc">From Glimpses of Nature.</span>)</h4>
+
+    <h3><span class="sc">By</span> A. WILSON.</h3>
+    <hr class="short">
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/205.png"><img width="200"
+             src="images/205.png"
+             alt="Fishing for sponges."></a>
+    </div>
+
+    <p>This morning, despite the promise of rain over-night, has
+    broken with all the signs and symptoms of a bright July day.
+    The Firth is bathed in sunlight, and the wavelets at full tide
+    are kissing the strand, making a soft musical ripple as they
+    retire, and as the pebbles run down the sandy slope on the
+    retreat of the waves. Beyond the farthest contact of the tide
+    is a line of seaweed dried and desiccated, mixed up with which,
+    in confusing array, are masses of shells, and such <i>olla
+    podrida</i> of the sea.</p>
+
+    <p>Tossed up at our very feet is a dried fragment of sponge,
+    which doubtless the unkind waves tore from its rocky bed. It is
+    not a large portion of sponge this, but its structure is
+    nevertheless to be fairly made out, and some reminiscences of
+    its history gleaned, for the sake of occupying the by no means
+    "bad half-hour" before breakfast. "What is a sponge?" is a
+    question <span class="pagenum"><a id="page206"></a>[pg 206]</span> which you may well ask as a
+       necessary preliminary to the understanding of its
+       personality.</p><br>
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/206.png"><img width="250"
+             src="images/206.png"
+             alt="A SPONGE ATTACHED TO ITS ROCKY BED."></a><br>
+        A SPONGE ATTACHED TO ITS ROCKY BED.
+    </div>
+
+    <p>The questionings of childhood and the questionings of
+    science run in precisely similar grooves. "What is it?" and
+    "How does it live?" and "Where does it come from?" are equally
+    the inquiries of childhood, and of the deepest philosophy which
+    seeks to determine the whole history of life. This morning, we
+    cannot do better than follow in the footsteps of the child, and
+    to the question, "What is a sponge?" I fancy science will be
+    able to return a direct answer. First of all, we may note that
+    a sponge, as we know it in common life, is the horny skeleton
+    or framework which was made by, and which supported, the living
+    parts. These living parts consist of minute masses of that
+    living jelly to which the name of <i>protoplasm</i> has been
+    applied. This, in truth, is the universal matter of life. It is
+    the one substance with which life everywhere is associated, and
+    as we see it simply in the sponge, so also we behold it (only
+    in more complex guise) in the man. Now, the living parts of
+    this dried cast-away sponge were found both <span class=
+    "pagenum"><a id="page207"></a>[pg 207]</span> in its interior and on its
+       surface. They lined the canals that everywhere permeate the
+       sponge-substance, and microscopic examination has told us a
+       great deal about their nature.</p>
+
+    <div class="figright"
+         style="width:400px;">
+        <a href="images/207.png"><img width="400"
+             src="images/207.png"
+             alt=
+           "FIG. 1. DEVELOPMENT OF A SPONGE (Olynthus)."></a><br>
+        FIG. 1. DEVELOPMENT OF A SPONGE (<i>Olynthus</i>).
+
+        <p>1. The egg. 2, 3, and 4. The process of egg-division. 5
+        and 6. The gastrula-stage. 7. The perfect sponge.</p>
+    </div>
+
+    <p>For, whether found in the canals of the sponge themselves,
+    or embedded in the sponge-substance, the living
+    sponge-particles are represented each by a semi-independent
+    mass of protoplasm. So that the first view I would have you
+    take of the sponge as a living mass, is, that it is a colony
+    and not a single unit. It is composed, in other words, of
+    aggregated masses of living particles, which bud out one from
+    the other, and manufacture the supporting skeleton we know as
+    "the sponge of commerce" itself. Under the microscope, these
+    living sponge-units appear in various guises and shapes. Some
+    of them are formless, and, as to shape, ever-altering masses,
+    resembling that familiar animalcule of our pools we know as the
+    <i>Amoeba</i>. These members of the sponge-colony form the bulk
+    of the population. They are embedded in the sponge substance;
+    they wander about through the meshes of the sponge;
+          <span class="pagenum"><a id="page208"></a>[pg 208]</span> they seize food and
+       flourish and grow; and they probably also give origin to the
+       "eggs" from which new sponges are in due course
+       produced.</p>
+
+    <p>More characteristic however, are certain units of this
+    living sponge-colony which live in the lining membrane of the
+    canals. In point of fact, a sponge is a kind of Venice, a
+    certain proportion of whose inhabitants, like those of the
+    famous Queen of the Adriatic herself, live on the banks of the
+    waterways. Just as in Venice we find the provisions for the
+    denizens of the city brought to the inhabitants by the canals,
+    so from the water, which, as we shall see, is perpetually
+    circulating through a sponge, the members of the sponge-colony
+    receive their food.</p>
+
+    <p>Look, again, at the sponge-fragment which lies before us.
+    You perceive half a dozen large holes or so, each opening on a
+    little eminence, as it were. These apertures, bear in mind, we
+    call <i>oscula</i>. They are the exits of the sponge-domain.
+    But a close inspection of a sponge shows that it is riddled
+    with finer and smaller apertures. These latter are the
+    <i>pores</i>, and they form the entrances to the
+    sponge-domain.</p>
+
+    <p>On the banks of the canal you may see growing plentifully in
+    summer time a green sponge, which is the common fresh-water
+    species. Now, if you drop a living specimen of this species
+    into a bowl of water, and put some powdered indigo into the
+    water, you may note how the currents are perpetually being
+    swept in by the pores and out by the oscula. In every living
+    sponge this perpetual and unceasing circulation of water
+    proceeds. This is the sole evidence the unassisted sight
+    receives of the vitality of the sponge-colony,
+          <span class="pagenum"><a id="page209"></a>[pg 209]</span> and the importance of this
+       circulation in aiding life in these depths, to be fairly
+       carried out cannot readily be over-estimated.</p>
+
+    <div class="figcenter"
+         style="width:300px;">
+        <a href="images/233.jpg"><img width="300"
+             src="images/233sm.jpg"
+             alt="WHERE SPONGES GROW."></a><br>
+        WHERE SPONGES GROW.
+    </div>
+
+    <p>Let us now see how this circulation is maintained.
+    Microscopically regarded, we see here and there, in the sides
+    of the sponge-passages, little chambers and recesses which
+    remind one of the passing-places in a narrow canal. Lining
+    these chambers, we see living sponge-units of a type different
+    from the shapeless specks we noted to occur in the meshes of
+    the sponge substance itself. The units of the recesses each
+    consist of a living particle, whose free extremity is raised
+    into a kind of collar, from which projects a lash-like filament
+    known as a flagellum.</p>
+
+    <p>This lash is in constant movement. It waves to and fro in
+    the water, and the collection of lashes we see in any one
+    chamber acts as a veritable brush, which by its movement not
+    only sweeps water in by the pores, but sends it onwards through
+    the sponge, and in due time sends it out by the bigger holes,
+    or oscula. This constant circulation in the sponge discharges
+    more than one important function. For, as already noted, it
+    serves the purpose of nutrition, in that the particles on which
+    sponge-life is supported are swept into the colony.</p>
+
+    <p>Again, the fresh currents of water carry with them the
+    oxygen gas which is a necessity of sponge existence, as of
+    human life; while, thirdly, waste matters, inevitably alike in
+    sponge and in man as the result of living, are swept out of the
+    colony, and discharged into the sea beyond. Our bit of sponge
+    has thus grown from a mere dry fragment into a living reality.
+    It is a <span class="pagenum"><a id="page210"></a>[pg 210]</span> community in which already,
+       low as it is, the work of life has come to be discharged by
+       distinct and fairly specialized beings.</p>
+
+    <p>The era of new sponge-life is inaugurated by means of
+    egg-development, although there exists another fashion (that of
+    gemmules or buds) whereby out of the parental substance young
+    sponges are produced. A sponge-egg develops, as do all eggs, in
+    a definite cycle. It undergoes division (Fig. 1); its one cell
+    becomes many; and its many cells arrange themselves first of
+    all into a cup-like form (5, 6 and 7), which may remain in this
+    shape if the sponge is a simple one, or become developed into
+    the more complex shape of the sponges we know.</p>
+
+    <p>In every museum you may see specimens of a beautiful
+    vase-like structure seemingly made of spun-glass. This is a
+    flinty sponge, the "Venus flower-basket," whose presence in the
+    sponge family redeems it from the charge that it contains no
+    things of beauty whatever. So, too, the rocks are full of
+    fossil-sponges, many of quaint form. Our piece of sponge, as we
+    may understand, has yet other bits of history attached to
+    it.... Meanwhile, think over the sponge and its ways, and learn
+    from it that out of the dry things of life, science weaves many
+    a fairy tale.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/210.png"><img width="500"
+             src="images/210.png"
+             alt="Under the sea."></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="page211"></a>[pg 211]</span>
+
+    <h2>THE GREATEST SEA-WAVE EVER KNOWN</h2>
+
+    <h4>(<span class="sc">From Light Science in Leisure
+    Hours.</span>)</h4>
+
+    <h3><span class="sc">By</span> R.A. PROCTOR.</h3>
+    <hr class="short">
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/211.png"><img width="200"
+             src="images/211.png"
+             alt="sea wave"></a>
+    </div>
+
+    <p>August 13th, 1868, one of the most terrible calamities which
+    has ever visited a people befell the unfortunate inhabitants of
+    Peru. In that land earthquakes are nearly as common as rain
+    storms are with us; and shocks by which whole cities are
+    changed into a heap of ruins are by no means infrequent. Yet
+    even in Peru, "the land of earthquakes," as Humboldt has termed
+    it, no such catastrophe as that of August, 1868, had occurred
+    within the memory of man. It was not one city which was laid in
+    ruins, but a whole empire. Those who perished were counted by
+    tens of thousands, while the property destroyed by the
+    earthquake was valued at millions of pounds sterling.</p>
+
+    <p>Although so many months have passed since this terrible
+    calamity took place, scientific men have been busily engaged,
+    until quite recently, in endeavoring to <span class=
+    "pagenum"><a id="page212"></a>[pg 212]</span> ascertain the real
+       significance of the various events which were observed
+       during and after the occurrence of the earthquake. The
+       geographers of Germany have taken a special interest in
+       interpreting the evidence afforded by this great
+       manifestation of Nature's powers. Two papers have been
+       written recently on the great earthquake of August 13th,
+       1868&mdash;one by Professor von Hochsteter, the other by
+       Herr von Tschudi, which present an interesting account of
+       the various effects, by land and by sea, which resulted from
+       the tremendous upheaving force to which the western flanks
+       of the Peruvian Andes were subjected on that day. The
+       effects on land, although surprising and terrible, only
+       differ in degree from those which have been observed in
+       other earthquakes. But the progress of the great sea-wave
+       which was generated by the upheaval of the Peruvian shores
+       and propagated over the whole of the Pacific Ocean differs
+       altogether from any earthquake phenomena before observed.
+       Other earthquakes have indeed been followed by oceanic
+       disturbances; but these have been accompanied by terrestrial
+       motions, so as to suggest the idea that they had been caused
+       by the motion of the sea-bottom or of the neighboring land.
+       In no instance has it ever before been known that a
+       well-marked wave of enormous proportions should have been
+       propagated over the largest ocean tract on our globe by an
+       earth-shock whose direct action was limited to a relatively
+       small region, and that region not situated in the centre,
+       but on one side of the wide area traversed by the wave.</p>
+
+    <p>We propose to give a brief sketch of the history of this
+    enormous sea-wave. In the first place, however,
+          <span class="pagenum"><a id="page213"></a>[pg 213]</span> it may be well to remind
+       the reader of a few of the more prominent features of the
+       great shock to which this wave owed its origin.</p>
+
+    <p>It was at Arequipa, at the foot of the lofty volcanic
+    mountain Misti, that the most terrible effects of the great
+    earthquake were experienced. Within historic times Misti has
+    poured forth no lava streams, but that the volcano is not
+    extinct is clearly evidenced by the fact that in 1542 an
+    enormous mass of dust and ashes was vomited forth from its
+    crater. On August 13th. 1868, Misti showed no signs of being
+    disturbed. So far as the volcanic neighbor was concerned, the
+    forty-four thousand inhabitants of Arequipa had no reason to
+    anticipate the catastrophe which presently befell them. At five
+    minutes past five an earthquake shock was experienced, which,
+    though severe, seems to have worked little mischief. Half a
+    minute later, however, a terrible noise was heard beneath the
+    earth; a second shock more violent than the first was felt, and
+    then began a swaying motion, gradually increasing in intensity.
+    In the-course of the first minute this motion had become so
+    violent that the inhabitants ran in terror out of their houses
+    into the streets and squares. In the next two minutes the
+    swaying movement had so increased that the more lightly built
+    houses were cast to the ground, and the flying people could
+    scarcely keep their feet. "And now," says Von Tschudi, "there
+    followed during two or three minutes a terrible scene. The
+    swaying motion which had hitherto prevailed changed into fierce
+    vertical upheaval. The subterranean roaring increased in the
+    most terrifying manner; then were heard the heart-piercing
+    shrieks of the <span class="pagenum"><a id="page214"></a>[pg 214]</span> wretched people, the
+       bursting of walls, the crashing fall of houses and churches,
+       while over all rolled thick clouds of a yellowish-black
+       dust, which, had they been poured forth many minutes longer,
+       would have suffocated thousands." Although the shocks had
+       lasted but a few minutes, the whole town was destroyed. Not
+       one building remained uninjured, and there were few which
+       did not lie in shapeless heaps of ruins.</p>
+
+    <p>At Tacna and Arica the earth-shock was less severe, but
+    strange and terrible phenomena followed it. At the former place
+    a circumstance occurred the cause and nature of which yet
+    remain a mystery. About three hours after the
+    earthquake&mdash;in other words, at about eight o'clock in the
+    evening&mdash;an intensely brilliant light made its appearance
+    above the neighboring mountains. It lasted for fully half an
+    hour, and has been ascribed to the eruption of some as yet
+    unknown volcano.</p>
+
+    <p>At Arica the sea-wave produced even more destructive effects
+    than had been caused by the earthquake. About twenty minutes
+    after the first earth-shock the sea was seen to retire, as if
+    about to leave the shores wholly dry; but presently its waters
+    returned with tremendous force. A mighty wave, whose length
+    seemed immeasurable, was seen advancing like a dark wall upon
+    the unfortunate town, a large part of which was overwhelmed by
+    it. Two ships, the Peruvian corvette America, and the United
+    States "double-ender" Wateree, were carried nearly half a mile
+    to the north of Arica beyond the railroad which runs to Tacna,
+    and there left stranded high and dry. This enormous wave was
+    considered by the English vice-consul at Arica to have been
+    fully fifty feet in height.</p><span class=
+       "pagenum"><a id="page215"></a>[pg 215]</span>
+
+    <p>At Chala three such waves swept in after the first shocks of
+    earthquake. They overflowed nearly the whole of the town, the
+    sea passing more than half a mile beyond its usual limits.</p>
+
+    <p>At Islay and Iquique similar phenomena were manifested. At
+    the former town the lava flowed in no less than five times, and
+    each time with greater force. Afterward the motion gradually
+    diminished, but even an hour and a half after the commencement
+    of this strange disturbance the waves still ran forty feet
+    above the ordinary level. At Iquique the people beheld the
+    inrushing wave while it was still a great way off. A dark blue
+    mass of water some fifty feet in height was seen sweeping in
+    upon the town with inconceivable rapidity. An island lying
+    before the harbor was completely submerged by the great wave,
+    which still came rushing on black with the mud and slime it had
+    swept from the sea-bottom. Those who witnessed its progress
+    from the upper balconies of their houses, and presently saw its
+    black mass rushing close beneath their feet, looked on their
+    safety as a miracle. Many buildings were indeed washed away,
+    and in the low-lying parts of the town there was a terrible
+    loss of life. After passing far inland, the wave slowly
+    returned sea-ward, and, strangely enough, the sea, which
+    elsewhere heaved and tossed for hours after the first great
+    wave had swept over it, here came soon to rest.</p>
+
+    <p>At Callao a yet more singular instance was afforded of the
+    effect which circumstances may have upon the motion of the sea
+    after a great earthquake has disturbed it. In former
+    earthquakes Callao has suffered terribly from the effects of
+    the great sea-wave. In <span class="pagenum"><a id="page216"></a>[pg 216]</span> fact, on two occasions the
+       whole town has been destroyed, and nearly all its
+       inhabitants have been drowned, through the inrush of
+       precisely such waves as flowed into the ports of Arica and
+       Chala. But upon this occasion the centre of subterranean
+       disturbance must have been so situated that either the wave
+       was diverted from Callao, or, more probably, two waves
+       reached Callao from different sources and at different
+       times, so that the two undulations partly counteracted each
+       other. Certain it is that, although the water retreated
+       strangely from the coast near Callao, insomuch that a wide
+       tract of the sea-bottom was uncovered, there was no
+       inrushing wave comparable with those described above. The
+       sea afterward rose and fell in an irregular manner, a
+       circumstance confirming the supposition that the disturbance
+       was caused by two distinct oscillations. Six hours after the
+       occurrence of the earth-shock the double oscillations seemed
+       for a while to have worked themselves into unison, for at
+       this time three considerable waves rolled in upon the town.
+       But clearly these waves must not be compared with those
+       which in other instances had made their appearance within
+       half an hour of the earth-throes. There is little reason to
+       doubt that if the separate oscillations had re-enforced each
+       other earlier, Callao would have been completely destroyed.
+       As it was, a considerable amount of mischief was effected;
+       but the motion of the sea presently became irregular again,
+       and so continued until the morning of August 14th, when it
+       began to ebb with some regularity. But during the 14th there
+       were occasional renewals of the irregular motion, and
+       several days <span class="pagenum"><a id="page217"></a>[pg 217]</span> elapsed before the regular
+       ebb and flow of the sea were resumed.</p>
+
+    <p>Such were among the phenomena presented in the region where
+    the earthquake itself was felt. It will be seen at once that
+    within this region, or rather along that portion of the
+    sea-coast which falls within the central region of disturbance,
+    the true character of the sea-wave generated by the earthquake
+    could not be recognized. If a rock fall from a lofty cliff into
+    a comparatively shallow sea, the water around the place where
+    the rock has fallen is disturbed in an irregular manner. The
+    sea seems at one place to leap up and down; elsewhere one wave
+    seems to beat against another, and the sharpest eye can detect
+    no law in the motion of the seething waters. But presently,
+    outside the scene of disturbance, a circular wave is seen to
+    form, and if the motion of this wave be watched it is seen to
+    present the most striking contrast with the turmoil and
+    confusion at its centre. It sweeps onward and outward in a
+    regular undulation. Gradually it loses its circular figure
+    (unless the sea-bottom happens to be unusually level), showing
+    that although its motion is everywhere regular, it is not
+    everywhere equally swift. A wave of this sort, though
+    incomparably vaster, swept swiftly away on every side from the
+    scene of the great earthquake near the Peruvian Andes. It has
+    been calculated that the width of this wave varied from one
+    million to five million feet, or, roughly, from two hundred to
+    one thousand miles, while, when in mid-Pacific, the length of
+    the wave, measured along its summit in a widely-curved path
+    from one side to another of the great <span class=
+    "pagenum"><a id="page218"></a>[pg 218]</span> ocean, cannot have been
+       less than eight thousand miles.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/218.jpg"><img width="500"
+             src="images/218.jpg"
+             alt=
+           "OVER A LARGE PORTION OF ITS COURSE ITS PASSAGE WAS UNNOTED."></a><br>
+        OVER A LARGE PORTION OF ITS COURSE ITS PASSAGE WAS UNNOTED.
+    </div>
+
+    <p>We cannot tell how deep-seated was the centre of
+    subterranean action; but there can be no doubt it was very deep
+    indeed, because otherwise the shock felt in towns separated
+    from each other by hundreds of miles could not have been so
+    nearly contemporaneous. Therefore the portion of the earth's
+    crust upheaved must have been enormous, for the length of the
+    region where the direct effects of the earthquake were
+    perceived is estimated by Professor von Hochsteter at no
+    <span class="pagenum"><a id="page219"></a>[pg 219]</span> less than two hundred and
+       forty miles. The breadth of the region is unknown, because
+       the slope of the Andes on one side and the ocean on the
+       other concealed the motion of the earth's crust.</p>
+
+    <p>The great ocean-wave swept, as we have said, in all
+    directions around the scene of the earth-throe. Over a large
+    part of its course its passage was unnoted, because in the open
+    sea the effects even of so vast an undulation could not be
+    perceived. A ship would slowly rise as the crest of the great
+    wave passed under her, and then as slowly sink again. This may
+    seem strange, at first sight, when it is remembered that in
+    reality the great sea-wave we are considering swept at the rate
+    of three or four hundred sea-miles an hour over the larger part
+    of the Pacific. But when the true character of ocean-waves is
+    understood, when it is remembered that there is no transference
+    of the water itself at this enormous rate, but simply a
+    transmission of motion (precisely as when in a high wind waves
+    sweep rapidly over a cornfield, while yet each cornstalk
+    remains fixed in the ground), it will be seen that the effects
+    of the great sea-wave could only be perceived near the shore.
+    Even there, as we shall presently see, there was much to convey
+    the impression that the land itself was rising and falling
+    rather than that the deep was moved. But among the hundreds of
+    ships which were sailing upon the Pacific when its length and
+    breadth were traversed by the great sea-wave, there was not one
+    in which any unusual motion was perceived.</p>
+
+    <p>In somewhat less than three hours after the occurrence of
+    the earthquake the ocean-wave inundated the <span class=
+    "pagenum"><a id="page220"></a>[pg 220]</span> port of Coquimbo, on the
+       Chilean seaboard, some eight hundred miles from Arica. An
+       hour or so later it had reached Constitucion, four hundred
+       and fifty miles farther south; and here for some three hours
+       the sea rose and fell with strange violence. Farther south,
+       along the shore of Chile, even to the island of Chiloe, the
+       shore-wave travelled, though with continually diminishing
+       force, owing, doubtless, to the resistance which the
+       irregularities of the shore opposed to its progress.</p>
+
+    <p>The northerly shore-wave seems to have been more
+    considerable; and a moment's study of a chart of the two
+    Americas will show that this circumstance is highly
+    significant. When we remember that the principal effects of the
+    land-shock were experienced within that angle which the
+    Peruvian Andes form with the long north-and-south line of the
+    Chilean and Bolivian Andes, we see at once that, had the centre
+    of the subterranean action been near the scene where the most
+    destructive effects were perceived, no sea-wave, or but a small
+    one, could have been sent toward the shores of North America.
+    The projecting shores of northern Peru and Ecuador could not
+    have failed to divert the sea-wave toward the west; and though
+    a reflected wave might have reached California, it would only
+    have been after a considerable interval of time, and with
+    dimensions much less than those of the sea-wave which travelled
+    southward. When we see that, on the contrary, a wave of even
+    greater proportions travelled toward the shores of North
+    America, we seem forced to the conclusion that the centre of
+    the subterranean action must have been so far to the west that
+    the sea- <span class="pagenum"><a id="page221"></a>[pg 221]</span> wave generated by it had a
+       free course to the shores of California.</p>
+
+    <p>Be this as it may, there can be no doubt that the wave which
+    swept the shores of Southern California, rising upward of sixty
+    feet above the ordinary sea-level, was absolutely the most
+    imposing of all the indirect effects of the great earthquake.
+    When we consider that even in San Pedro Bay, fully five
+    thousand miles from the centre of disturbance, a wave twice the
+    height of an ordinary house rolled in with unspeakable violence
+    only a few hours after the occurrence of the earth-throe, we
+    are most strikingly impressed with the tremendous energy of the
+    earth's movement.</p>
+
+    <p>Turning to the open ocean, let us track the great wave on
+    its course past the multitudinous islands which dot the surface
+    of the Pacific.</p>
+
+    <p>The inhabitants of the Sandwich Islands, which lie about six
+    thousand three hundred miles from Arica, might have imagined
+    themselves safe from any effects which could be produced by an
+    earthquake taking place so far away from them. But on the night
+    between August 13th and 14th, the sea around this island group
+    rose in a surprising manner, insomuch that many thought the
+    islands were sinking, and would shortly subside altogether
+    beneath the waves. Some of the smaller islands, indeed, were
+    for a time completely submerged. Before long, however, the sea
+    fell again, and as it did so the observers "found it impossible
+    to resist the impression that the islands were rising bodily
+    out of the water." For no less than three days this strange
+    oscillation of the sea continued to be experienced, the most
+    remarkable ebbs and <span class="pagenum"><a id="page222"></a>[pg 222]</span> floods being noticed at
+       Honolulu, on the island of Woahoo.</p>
+
+    <p>But the sea-wave swept onward far beyond these islands.</p>
+
+    <p>At Yokohama, in Japan, more than ten thousand five hundred
+    miles from Arica, an enormous wave poured in on August 14th,
+    but at what hour we have no satisfactory record. So far as
+    distance is concerned, this wave affords most surprising
+    evidence of the stupendous nature of the disturbance to which
+    the waters of the Pacific Ocean had been subjected. The whole
+    circumference of the earth is but twenty-five thousand miles,
+    so that this wave had travelled over a distance considerably
+    greater than two-fifths of the earth's circumference. A
+    distance which the swiftest of our ships could not traverse in
+    less than six or seven weeks had been swept over by this
+    enormous undulation in the course of a few hours.</p>
+
+    <p>More complete details reach us from the Southern
+    Pacific.</p>
+
+    <p>Shortly before midnight the Marquesas Isles and the
+    low-lying Tuamotu group were visited by the great wave, and
+    some of these islands were completely submerged by it. The
+    lonely Opara Isle, where the steamers which run between Panama
+    and New Zealand have their coaling station, was visited at
+    about half-past eleven in the evening by a billow which swept
+    away a portion of the coal depot. Afterward great waves came
+    rolling in at intervals of about twenty minutes, and several
+    days elapsed before the sea resumed its ordinary ebb and
+    flow.</p>
+
+    <p>It was not until about half-past two on the morning
+    <span class="pagenum"><a id="page223"></a>[pg 223]</span> of August 14th that the
+       Samoa Isles (sometimes called the Navigator Islands) were
+       visited by the great wave. The watchmen startled the
+       inhabitants from their sleep by the cry that the sea was
+       about to overwhelm them; and already, when the terrified
+       people rushed from their houses, the sea was found to have
+       risen far above the highest water-mark. But it presently
+       began to sink again, and then commenced a series of
+       oscillations, which lasted for several days, and were of a
+       very remarkable nature. Once in every quarter of an hour the
+       sea rose and fell, but it was noticed that it rose twice as
+       rapidly as it sank. This peculiarity is well worth
+       remarking. The eminent physicist Mallet speaks thus (we
+       follow Lyell's quotation) about the waves which traverse an
+       open sea: "The great sea-wave, advancing at the rate of
+       several miles in a minute, consists, in the deep ocean, of a
+       long, low swell of enormous volume, having an equal slope
+       before and behind, and that so gentle that it might pass
+       under a ship without being noticed. But when it reaches the
+       edge of soundings, its front slope becomes short and steep,
+       while its rear slope is long and gentle." On the shores
+       visited by such a wave, the sea would appear to rise more
+       rapidly than it sank. We have seen that this happened on the
+       shores of the Samoa group, and therefore the way in which
+       the sea rose and fell on the days following the great
+       earthquake gave significant evidence of the nature of the
+       sea-bottom in the neighborhood of these islands. As the
+       change of the great wave's figure could not have been
+       quickly communicated, we may conclude with certainty that
+       the Samoan Islands are the summits of lofty mountains, whose
+       sloping sides extend far toward the east.</p><span class=
+       "pagenum"><a id="page224"></a>[pg 224]</span>
+
+    <p>This conclusion affords interesting evidence of the
+    necessity of observing even the seemingly trifling details of
+    important phenomena.</p>
+
+    <p>The wave which visited the New Zealand Isles was altogether
+    different in character, affording a noteworthy illustration of
+    another remark of Mallet's. He says that where the sea-bottom
+    slopes in such a way that there is water of some depth close
+    inshore, the great wave may roll in and do little damage; and
+    we have seen that so it happened in the case of the Samoan
+    Islands. But he adds that, "where the shore is shelving there
+    will be first a retreat of the water, and then the wave will
+    break upon the beach and roll far in upon the land." This is
+    precisely what happened when the great wave reached the eastern
+    shores of New Zealand, which are known to shelve down to very
+    shallow water, continuing far away to sea toward the east.</p>
+
+    <p>At about half-past three on the morning of August 14th the
+    water began to retreat in a singular manner from the port of
+    Littleton, on the eastern shores of the southernmost of the New
+    Zealand Islands. At length the whole port was left entirely
+    dry, and so remained for about twenty minutes. Then the water
+    was seen returning like a wall of foam ten or twelve feet in
+    height, which rushed with a tremendous noise upon the port and
+    town. Toward five o'clock the water again retired, very slowly
+    as before, not reaching its lowest ebb until six. An hour later
+    a second huge wave inundated the port. Four times the sea
+    retired and returned with great power at intervals of about two
+    hours. Afterward the oscillation of the water was less
+    <span class="pagenum"><a id="page225"></a>[pg 225]</span> considerable, but it had
+       not wholly ceased until August 17th, and only on the 18th
+       did the regular ebb and flow of the tide recommence.</p>
+
+    <p>Around the Samoa group the water rose and fell once in every
+    fifteen minutes, while on the shores of New Zealand each
+    oscillation lasted no less than two hours. Doubtless the
+    different depths of water, the irregular conformation of the
+    island groups, and other like circumstances, were principally
+    concerned in producing these singular variations. Yet they do
+    not seem fully sufficient to account for so wide a range of
+    difference. Possibly a cause yet unnoticed may have had
+    something to do with the peculiarity. In waves of such enormous
+    extent it would be quite impossible to determine whether the
+    course of the wave motion was directed full upon a line of
+    shore or more or less obliquely. It is clear that in the former
+    case the waves would seem to follow each other more swiftly
+    than in the latter, even though there were no difference in
+    their velocity.</p>
+
+    <p>Far on beyond the shores of New Zealand the great wave
+    coursed, reaching at length the coast of Australia. At dawn of
+    August 14th Moreton Bay was visited by five well-marked waves.
+    At Newcastle, on the Hunter River, the sea rose and fell
+    several times in a remarkable manner, the oscillatory motion
+    commencing at half-past six in the morning. But the most
+    significant evidence of the extent to which the sea-wave
+    travelled in this direction was afforded at Port Fairy,
+    Belfast, South Victoria. Here the oscillation of the water was
+    distinctly perceived at midday on August 14th; and yet, to
+    reach this point, the sea-wave must <span class=
+    "pagenum"><a id="page226"></a>[pg 226]</span> not only have travelled on
+       a circuitous course nearly equal in length to half the
+       circumference of the earth, but must have passed through
+       Bass's Straits, between Australia and Van Diemen's Land, and
+       so have lost a considerable portion of its force and
+       dimensions. When we remember that had not the effects of the
+       earth-shock on the water been limited by the shores of South
+       America, a wave of disturbance equal in extent to that which
+       travelled westward would have swept toward the east, we see
+       that the force of the shock was sufficient to have disturbed
+       the waters of an ocean covering the whole surface of the
+       earth. For the sea-waves which reached Yokohama in one
+       direction and Port Fairy in another had each traversed a
+       distance nearly equal to half the earth's circumference; so
+       that if the surface of the earth were all sea, waves setting
+       out in opposite directions from the centre of disturbance
+       would have met each other at the antipodes of their
+       starting-point.</p>
+
+    <p>It is impossible to contemplate the effects which followed
+    the great earthquake&mdash;the passage of a sea-wave of
+    enormous volume over fully one third of the earth's surface,
+    and the force with which, on the farthermost limits of its
+    range, the wave rolled in upon shores more than ten thousand
+    miles from its starting-place&mdash;without feeling that those
+    geologists are right who deny that the subterranean forces of
+    the earth are diminishing in intensity. It may be difficult,
+    perhaps, to look on the effects which are ascribed to ancient
+    earth-throes without imagining for a while that the power of
+    modern earthquakes is altogether less. But when we consider
+    fairly the share which time had in <span class=
+    "pagenum"><a id="page227"></a>[pg 227]</span> those ancient processes of
+       change, when we see that while mountain ranges were being
+       upheaved or valleys depressed to their present position,
+       race after race, and type after type appeared on the earth,
+       and lived out the long lives which belong to races and to
+       types, we are recalled to the remembrance of the great work
+       which the earth's subterranean forces are still engaged
+       upon. Even now continents are being slowly depressed or
+       upheaved; even now mountain ranges are being raised to a new
+       level, tablelands are in process of formation, and great
+       valleys are being gradually scooped out. It may need an
+       occasional outburst, such as the earthquake of August, 1868,
+       to remind us that great forces are at work beneath the
+       earth's surface. But, in reality, the signs of change have
+       long been noted. Old shore-lines shift their place, old
+       soundings vary; the sea advances in one place and retires in
+       another; on every side Nature's plastic hand is at work
+       modelling and remodelling the earth, in order that it may
+       always be a fit abode for those who are to dwell upon
+       it.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/227.png"><img width="500"
+             src="images/227.png"
+             alt="Ship on waves."></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="page228"></a>[pg 228]</span>
+
+    <h2>THE PHOSPHORESCENT SEA</h2>
+
+    <h4>(<span class="sc">From Studies of Animated
+    Nature.</span>)</h4>
+
+    <h3><span class="sc">By</span> W.S. DALLAS.</h3>
+    <hr class="short">
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/228.png"><img width="200"
+             src="images/228.png"
+             alt="Small Boat and Phosphorescence."></a>
+    </div>
+
+    <p>It is not merely on land that this phenomenon of
+    phosphorescence is to be seen in living forms. Among marine
+    animals, indeed, it is a phenomenon much more general, much
+    more splendid, and, we may add, much more familiar to those who
+    live on our coasts. There must be many in the British Isles who
+    have never had the opportunity of seeing the light of the
+    glow-worm, but there can be few of those who have frequented in
+    summer any part of our coasts, who have never seen that
+    beautiful greenish light which is then so often visible,
+    especially on our southern shores, when the water is disturbed
+    by the blade of an oar or the prow of a boat or ship. In some
+    cases, even on our own shores, the phenomenon is much more
+    brilliant, every rippling wave being crested with a line of the
+    same peculiar light, and in warmer seas exhibitions of this
+    kind are much more common. It is now <span class=
+    "pagenum"><a id="page229"></a>[pg 229]</span> known that this light is
+       due to a minute living form, to which we will afterward
+       return.</p>
+
+    <p>But before going on to speak in some detail of the organisms
+    to which the phosphorescence of the sea is due, it will be as
+    well to mention that the kind of phosphorescence just spoken of
+    is only one mode in which the phenomenon is exhibited on the
+    ocean. Though sometimes the light is shown in continuous lines
+    whenever the surface is disturbed, at other times, and,
+    according to M. de Quatrefages, more commonly, the light
+    appears only in minute sparks, which, however numerous, never
+    coalesce. "In the little channel known as the Sund de Chausez,"
+    he writes, "I have seen on a dark night each stroke of the oar
+    kindle, as it were, myriads of stars, and the wake of the craft
+    appeared in a manner besprinkled with diamonds." When such is
+    the case the phosphorescence is due to various minute animals,
+    especially crustaceans; that is, creatures which,
+    microscopically small as they are, are yet constructed more or
+    less on the type of the lobster or cray-fish.</p>
+
+    <p>At other times, again, the phosphorescence is still more
+    partial. "Great domes of pale gold with long streamers," to use
+    the eloquent words of Professor Martin Duncan, "move slowly
+    along in endless succession; small silvery disks swim, now
+    enlarging and now contracting, and here and there a green or
+    bluish gleam marks the course of a tiny, but rapidly rising and
+    sinking globe. Hour after hour the procession passes by, and
+    the fishermen hauling in their nets from the midst drag out
+    liquid light, and the soft sea jellies, crushed and torn
+    piecemeal, shine in every clinging <span class=
+    "pagenum"><a id="page230"></a>[pg 230]</span> particle. The night grows
+       dark, the wind rises and is cold, and the tide changes; so
+       does the luminosity of the sea. The pale spectres below the
+       surface sink deeper, and are lost to sight, but the
+       increasing waves are tinged here and there with green and
+       white, and often along a line, where the fresh water is
+       mixing with the salt in an estuary, there is a brightness so
+       intense that boats and shores are visible.... But if such
+       sights are to be seen on the surface, what must not be the
+       phosphorescence of the depths! Every sea-pen is glorious in
+       its light, in fact, nearly every eight-armed Alcyonarian is
+       thus resplendent, and the social Pyrosoma, bulky and a free
+       swimmer, glows like a bar of hot metal with a white and
+       green radiance."</p>
+
+    <p>Such accounts are enough to indicate how varied and how
+    general a phenomenon is the phosphorescence of the sea. To take
+    notice of one tithe of the points of interest summed up in the
+    paragraph just quoted would occupy many pages, and we must
+    therefore confine the attention to a few of the most
+    interesting facts relating to marine phosphorescence.</p>
+
+    <p>We will return to that form of marine luminosity to which we
+    first referred: what is known as the general or diffused
+    phosphorescence of the sea. From this mode of describing it the
+    reader must not infer that the surface of the ocean is ever to
+    be seen all aglow in one sheet of continuous light. So far, at
+    least, as was ever observed by M. de Quatrefages, who studied
+    this phenomenon carefully and during long periods on the coasts
+    of Brittany and elsewhere, no light was visible when the
+    surface of the sea was perfectly still. On the other hand, when
+    the sea exhibits in a high degree the <span class=
+    "pagenum"><a id="page231"></a>[pg 231]</span> phenomenon of diffused
+       phosphorescence no disturbance can be too slight to cause
+       the water to shine with that peculiar characteristic gleam.
+       Drop but a grain of sand upon its surface, and you will see
+       a point of light marking the spot where it falls, and from
+       that point as a centre a number of increasing wavelets, each
+       clearly defined by a line of light, will spread out in
+       circles all around.</p>
+
+    <p>The cause of this diffused phosphorescence was long the
+    subject of curiosity, and was long unknown, but more than a
+    hundred years ago (in 1764) the light was stated by M. Kigaut
+    to proceed from a minute and very lowly organism, now known as
+    <i>Noctiluca miliaris</i>; and subsequent researches have
+    confirmed this opinion. This Noctiluca is a spherical form of
+    not more than one-fiftieth of an inch in size, with a slight
+    depression or indentation at one point, marking the position of
+    a mouth leading to a short digestive cavity, and having close
+    beside it a filament, by means of which it probably moves
+    about. The sphere is filled with protoplasm, in which there is
+    a nucleus and one or more gaps, or "vacuoles." Such is nearly
+    all the structure that can be discerned with the aid of the
+    microscope in this simple organism.</p>
+
+    <p>Nevertheless, this lowly form is the chief cause of that
+    diffused phosphorescence which is sometimes seen over a wide
+    extent of the ocean. How innumerable the individuals belonging
+    to this species must therefore be, may be left to the
+    imagination. Probably the Noctiluca is not rivalled in this
+    respect even by miscroscopic unicellular algæ which compose the
+    "red snow."</p>
+
+    <p>By filtering sea-water containing Noctilucæ its light
+    <span class="pagenum"><a id="page232"></a>[pg 232]</span> can be concentrated, and it
+       has been found that a few teaspoonfuls will then yield light
+       enough to enable one to read holding a book at the ordinary
+       distance from the eyes&mdash;about ten inches.</p>
+
+    <p>A singular and highly remarkable case of diffused marine
+    phosphorescence was observed by Nordenskiöld during his voyage
+    to Greenland in 1883. One dark night, when the weather was calm
+    and the sea smooth, his vessel was steaming across a narrow
+    inlet called the Igaliko Fjord, when the sea was suddenly
+    observed to be illumined in the rear of the vessel by a broad
+    but sharply-defined band of light, which had a uniform,
+    somewhat golden sheen, quite unlike the ordinary bluish-green
+    phosphorescence of the sea. The latter kind of light was
+    distinctly visible at the same time in the wake of the vessel.
+    Though the steamer was going at the rate of from five to six
+    miles an hour, the remarkable sheet of light got nearer and
+    nearer. When quite close, it appeared as if the vessel were
+    sailing in a sea of fire or molten metal. In the course of an
+    hour the light passed on ahead, and ultimately it disappeared
+    in the remote horizon. The nature of this phenomenon
+    Nordenskiöld is unable to explain; and unfortunately he had not
+    the opportunity of examining it with the spectroscope.</p>
+
+    <p>If we come now to consider the more partial phosphorescence
+    of the sea, we find that it is due to animals belonging to
+    almost every group of marine forms&mdash;to Echinoderms, or
+    creatures of the sea-urchin and star-fish type, to Annelid
+    worm, to Medusidæ, or jelly-fish, as they are popularly called,
+    including the "great domes" and the "silvery disks" of the
+    <span class="pagenum"><a id="page233"></a>[pg 233]</span> passage above quoted from
+       Professor Martin Duncan, to Tunicates, among which is the
+       Pyrosoma, to Mollusks, Crustaceans, and in very many cases
+       to Actinozoa, or forms belonging to the type of the sea
+       anemone and the coral polyp.</p>
+
+    <p>Of these we will single out only a few for more special
+    notice.</p>
+
+    <p>Many of the Medusidæ, or jelly-fish, possess the character
+    of which we are speaking. In some cases the phosphorescence is
+    spontaneous among them, but in others it is not so; the
+    creature requires to be irritated or stimulated in some way
+    before it will emit the light. It is spontaneous, for example,
+    in the <i>Pelagia phosphorea</i>, but not in the allied
+    <i>Pelagia noctiluca</i>, a very common form in the
+    Mediterranean.</p>
+
+    <p>In both of the jelly-fishes just mentioned the
+    phosphorescence, when displayed at all, is on the surface of
+    the swimming disk, and this is most commonly the case with the
+    whole group. Sometimes, however, the phosphorescence is
+    specially localized. In some forms, as in <i>Thaumantius
+    pilosella</i> and other members of the same genus, it is seen
+    in buds at the base of tentacles given off from the margin of
+    the swimming-bell. In other cases it is situated in certain
+    internal organs, as in the canals which radiate from the centre
+    to the margin of the bell, or in the ovaries. It is from this
+    latter seat that the phosphorescence proceeds in <i>Oceania
+    pilata</i>, the form which gives out such a light that
+    Ehrenberg compared it to a lamp-globe lighted by a flame.</p>
+
+    <p>The property of emitting a phosphorescent light, sometimes
+    spontaneously and sometimes on being stimulated, is likewise
+    exemplified in the Ctenophora, a <span class=
+       "pagenum"><a id="page234"></a>[pg 234]</span> group resembling the
+       Medusidæ in the jelly-like character of their bodies, but
+       more closely allied in structure to the Actinozoa. But we
+       will pass over these cases in order to dwell more
+       particularly on the remarkable tunicate known as Pyrosoma, a
+       name indicative of its phosphorescent property, being
+       derived from two Greek words signifying fire-body. As shown
+       in the illustration Pyrosoma is not a single creature, but
+       is composed of a whole colony of individuals, each of which
+       is represented by one of the projections on the surface of
+       the tube, closed at one end, which they all combine to form.
+       The free end on the exterior contains the mouth, while there
+       is another opening in each individual toward the interior of
+       the tube. Such colonies, which swim about by the alternate
+       contraction and dilatation of the individuals composing
+       them, are pretty common in the Mediterranean, where they may
+       attain the length of perhaps fourteen inches, with a breadth
+       of about three inches. In the ocean they may reach a much
+       greater size. Mr. Moseley, in his "Notes of a Naturalist on
+       the Challenger," mentions a giant specimen which he once
+       caught in the deep-sea trawl, a specimen four feet in length
+       and ten inches in diameter, with "walls of jelly about an
+       inch in thickness."</p>
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/234.png"><img width="250"
+             src="images/234.png"
+             alt="A. PYROSOMA. B. PONITON."></a><br>
+        A. PYROSOMA. B. PONITON. (Magnified.)
+    </div>
+
+    <p>The same naturalist states that the light emitted by
+    <span class="pagenum"><a id="page235"></a>[pg 235]</span> this compound form is the
+       most beautiful of all kinds of phosphorescence. When
+       stimulated by a touch, or shake, or swirl of the water, it
+       "gives out a globe of bluish light, which lasts for several
+       seconds, as the animal drifts past several feet beneath the
+       surface, and then suddenly goes out." He adds that on the
+       giant specimen just referred to be wrote his name with his
+       finger as it lay on the deck in a tub at night, and in a few
+       seconds he had the gratification of seeing his name come out
+       in "letters of fire."</p>
+
+    <p>Among mollusks, the best known instance of phosphorescence
+    is in the rock-boring Pholas, the luminosity of which after
+    death is mentioned by Pliny. But it is not merely after death
+    that Pholas becomes luminous&mdash;a phenomenon perfectly
+    familiar even in the case of many fish, especially the herring
+    and mackerel. It was long before the luminosity of the living
+    animal was known, but this is now a well-ascertained fact; and
+    Panceri, an Italian naturalist, recently dead, has been able to
+    discover in this, as in several other marine phosphorescent
+    forms, the precise seat of the light-giving bodies, which he
+    has dissected out again and again for the sake of making
+    experiments in connection with this subject.</p>
+
+    <p>A more beautiful example of a phosphorescent mollusk is
+    presented by a sea-slug called <i>Phyllirhoë bucephala</i>.
+    This is a creature of from one and a half to two inches in
+    length, without a shell in the adult stage, and without even
+    gills. It breathes only by the general surface of the body. It
+    is common enough in the Mediterranean, but is not easy to see,
+    as it is almost perfectly transparent, so that it cannot be
+    distinguished <span class="pagenum"><a id="page236"></a>[pg 236]</span> without difficulty, by day
+       at least, from the medium in which it swims. By night,
+       however, it is more easily discerned, in consequence of its
+       property of emitting light. When disturbed or stimulated in
+       any way, it exhibits a number of luminous spots of different
+       sizes irregularly distributed all over it, but most thickly
+       aggregated on the upper and under parts. These
+       phosphorescent spots, it is found, are not on the surface,
+       but for the most part represent so many large cells which
+       form the terminations of nerves, and are situated underneath
+       the transparent cuticle. The spots shine with exceptional
+       brilliancy when the animal is withdrawn from the water and
+       stimulated by a drop of ammonia.</p>
+
+    <p>Among the Annelid worms a species of <i>Nereis</i>, or
+    sea-centipedes, has earned by its phosphorescent property the
+    specific name of <i>noctiluca</i> (night-shining), and the same
+    property is very beautifully shown in <i>Polynoë</i>, a near
+    ally of the familiar sea-mouse. M. de Quatrefages speaks with
+    enthusiasm of the beauty of the spectacle presented by this
+    latter form when examined under a microscope magnifying to the
+    extent of a hundred diameters. He then found, as he did in the
+    great majority of cases which he studied, that the
+    phosphorescence was confined to the motor muscles, and was
+    manifested solely when these were in the act of contracting,
+    manifested, too, not in continuous lines along the course of
+    the muscles, but in rows of brilliant points.</p>
+
+    <p>More interesting than the Annelids, however, are the
+    Alcyonarian Actinozoa. The Actinozoa have already been
+    described as formed on the type of the sea-anemone and the
+    coral polyp, that is, they are all animals with a radiate
+    structure, attached to one end, and <span class=
+    "pagenum"><a id="page237"></a>[pg 237]</span> having their only opening
+       at the other end, which is surrounded by tentacles. In the
+       Alcyonarian forms belonging to this great group these
+       tentacles are always eight in number, and fringed on both
+       sides. Moreover, these forms are almost without exception
+       compound. Like the Pyrosoma, they have a common life
+       belonging to a whole stock or colony, as well as an
+       individual life.</p>
+
+    <p>Now, throughout this sub-division of the Actinozoa
+    phosphorescence is a very general phenomenon. Professor
+    Moseley, already quoted as a naturalist accompanying the
+    Challenger expedition, informs us that "all the Alcyonarians
+    dredged by the Challenger in deep water were found to be
+    brilliantly phosphorescent when brought to the surface."</p>
+
+    <p>Among these Alcyonarians are the sea-pens mentioned in the
+    quotation above made from Professor Martin Duncan. Each sea-pen
+    is a colony of Alcyonarians, and the name is due to the
+    singular arrangement of the individuals upon the common stem.
+    This stem is supported internally by a coral rod, but its outer
+    part is composed of fleshy matter belonging to the whole
+    colony. The lower portion of it is fixed in the muddy bottom of
+    the sea, but the upper portion is free, and gives off a number
+    of branches, on which the individual polyps are seated. The
+    whole colony thus has the appearance of a highly ornamental
+    pen.</p>
+
+    <p>There is one British species, <i>Pennatula phosphorea</i>,
+    which is found in tolerably deep water, and is from two to four
+    inches in length. The specific name again indicates the
+    phosphorescent quality belonging to it. When irritated, it
+    shines brilliantly, and the curious thing is that the
+    phosphorescence travels gradually on from <span class=
+    "pagenum"><a id="page238"></a>[pg 238]</span> polyp to polyp, starting
+       from the point at which the irritation is applied. If the
+       lower part of the stem is irritated, the phosphorescence
+       passes gradually upwards along each pair of branches in
+       succession; but if the top is irritated the phosphorescence
+       will pass in the same way downwards. When both top and
+       bottom are irritated simultaneously two luminous currents
+       start at once, and, meeting in the middle, usually become
+       extinguished there; but on one occasion Panceri found that
+       the two crossed, and each completed its course independently
+       of the other. Those of our readers who have had
+       opportunities of making or seeing experiments with the
+       sensitive plant (<i>Mimosa pudica</i>) will be reminded of
+       the way in which, when that plant is irritated, the
+       influence travels regularly on from pinnules to pinnules and
+       pinnae to pinnae.</p>
+
+    <p>In all the cases mentioned the phenomenon of phosphorescence
+    is exhibited by invertebrate animals; but though rare, it is
+    not an unknown phenomenon even in living vertebrates. In a
+    genus of deep-sea fishes called Stomias, Gunther mentions that
+    a "series of phosphorescent dots run along the lower side of
+    the head, body, and tail." Several other deep-sea fishes,
+    locally phosphorescent, seem to have been dredged up by the
+    French ship Talisman in its exploring cruise off the west coast
+    of Northern Africa in 1883. During the same expedition, a
+    number of deep-sea phosphorescent crustaceans were dredged up,
+    the phosphorescence being in some cases diffused over the whole
+    body, in other cases localized to particular areas. In deep-sea
+    forms the phenomenon is, in fact, so common, as to have given
+    rise to the theory that in the depths of the ocean, where the
+    light <span class="pagenum"><a id="page239"></a>[pg 239]</span> of the sun cannot
+       penetrate, the phosphorescence of various organisms diffuse
+       a light which limits the domain of absolute darkness.</p>
+
+    <p>So much by way of illustration regarding the phosphorescence
+    exhibited by animals, terrestrial and marine; but it ought to
+    be noticed that there are also a few cases in which the same
+    phenomenon is to be witnessed in plants. These are not so
+    numerous as was at one time supposed, the property having been
+    mistakenly ascribed to some plants not really luminous.</p>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/239.png"><img width="600"
+             src="images/239.png"
+             alt="A PHOSPHORESCENT SEA."></a><br>
+        A PHOSPHORESCENT SEA.
+    </div>
+
+    <p>In some instances the mistake appears to have been due to a
+    subjective effect produced by brilliantly colored (red or
+    orange) flowers, such as the great Indian cress, the orange
+    lily, the sunflower, and the marigold. The fact that such
+    flowers do give out in the dusk sudden flashes of light has
+    often been stated on the authority of a daughter of Linnæus,
+    subsequently <span class="pagenum"><a id="page240"></a>[pg 240]</span> backed by the assertions of
+       various other observers. But most careful observers seem to
+       be agreed that the supposed flashes of light are in reality
+       nothing else than a certain dazzling of the eyes.</p>
+
+    <p>In another case, in which a moss, <i>Schistostega
+    osmundacea</i>, has been stated to be phosphorescent, the
+    effect is said to be really due to the refraction and
+    reflection of light by minute crystals scattered over its
+    highly cellular leaves, and not to be produced at all where the
+    darkness is complete.</p>
+
+    <p>Among plants, genuine phosphorescence is to be found chiefly
+    in certain fungi, the most remarkable of which is
+    <i>Rhizomorpha subterranea</i>, which is sometimes to be seen
+    ramifying over the walls of dark, damp mines, caverns, or
+    decayed towers, and emitting at numerous points a mild
+    phosphorescent light, which is sometimes bright enough to allow
+    of surrounding objects being distinguished by it. The name of
+    "vegetable glow-worm" has sometimes been applied to this
+    curious growth.</p>
+
+    <p>Among other phosphorescent fungi are several species of
+    Agaricus, including the <i>A. olearius</i> of Europe, <i>A.
+    Gardneri</i> of Brazil, and <i>A. lampas</i> of Australia, and
+    besides the members of this genus, <i>Thelaphora cærulea</i>,
+    which is the cause of the phosphorescent light sometimes to be
+    seen on decaying wood&mdash;the "touchwood" which many boys
+    have kept in the hope of seeing this light displayed. The milky
+    juice of a South American Euphorbia (<i>E. phosphorea</i>) is
+    stated by Martins to be phosphorescent when gently heated. But
+    phosphorescence is evidently not so interesting and important a
+    phenomenon in the vegetable as it is in the animal
+    kingdom.</p><span class="pagenum"><a id="page241"></a>[pg 241]</span>
+
+    <p>The whole phenomenon is one that gives rise to a good many
+    questions which it is not easy to answer, and this is
+    especially true in the case of animal phosphorescence. What is
+    the nature of the light? What are the conditions under which it
+    is manifested? What purpose does it serve in the animal
+    economy?</p>
+
+    <p>As to the nature of the light, the principal question is
+    whether it is a direct consequence of the vital activity of the
+    organism in which it is seen, of such a nature that no further
+    explanation can be given of it, any more than we can explain
+    why a muscle is contracted under the influence of a
+    nerve-stimulus; or whether it is due to some chemical process
+    more or less analogous to the burning of a candle.</p>
+
+    <p>The fact of luminosity appearing to be in certain cases
+    directly under the control of the creature in which it is
+    found, and the fact of its being manifested in many forms, as
+    M. de Quatrefages found, only when muscular contraction was
+    taking place, would seem to favor the former view. On the other
+    hand, it is against this view that the phosphorescence is often
+    found to persist after the animal is dead, and even in the
+    phosphorescent organs for a considerable time after they have
+    been extracted from the body of the animal. In the glow-worm
+    the light goes on shining for some time after the death of the
+    insect, and even when it has become completely extinguished it
+    can be restored for a time by the application of a little
+    moisture. Further, both Matteucci and Phipson found that when
+    the luminous substance was extracted from the insect it would
+    keep on glowing for thirty or forty minutes.</p>
+
+    <p>In Pholas the light is still more persistent, and it is
+    <span class="pagenum"><a id="page242"></a>[pg 242]</span> found that when the dead
+       body of this mollusk is placed in honey, it will retain for
+       more than a year the power of emitting light when plunged in
+       warm water.</p>
+
+    <p>The investigations of recent years have rendered it more and
+    more probable that the light exhibited by phosphorescent
+    organisms is due to a chemical process somewhat analogous to
+    that which goes on in the burning of a candle. This latter
+    process is one of rapid oxidation. The particles of carbon
+    supplied by the oily matter that feeds the candle become so
+    rapidly combined with oxygen derived from the air that a
+    considerable amount of light, along with heat, is produced
+    thereby. Now, the phenomenon of phosphorescence in organic
+    forms, whether living or dead, appears also to be due to a
+    process of oxidation, but one that goes on much more slowly
+    than in the case of a lighted candle. It is thus more closely
+    analogous to what is observed in the element phosphorus itself,
+    which owes its name (meaning "light-bearer") to the fact that
+    when exposed to the air at ordinary temperatures it glows in
+    the dark, in consequence of its becoming slowly combined with
+    oxygen.</p>
+
+    <p>At one time it was believed that the presence of oxygen was
+    not necessary to the exhibition of phosphorescence in organic
+    forms, but it has now been placed beyond doubt that this is a
+    mistake. Oxygen has been proved to be indispensable, and hence
+    we see a reason for the luminous organs in the glow-worm being
+    so intimately connected, as above mentioned, with the air-tubes
+    that ramify through the insect.</p>
+
+    <p>This fact of itself might be taken as a strong indication of
+    the chemical nature of the process to which <span class=
+    "pagenum"><a id="page243"></a>[pg 243]</span> phosphorescence is due. But
+       the problem has been made the subject of further
+       investigations which have thrown more light upon it. It was
+       long known that there were various inorganic bodies besides
+       phosphorus which emitted a phosphorescent light in the dark,
+       at least after being exposed to the rays of the sun; but it
+       was not till quite recently that any organic compound was
+       known to phosphoresce at ordinary temperatures.</p>
+
+    <p>This discovery was made by a Polish chemist, named
+    Bronislaus Radziszewski, who followed it up with a long series
+    of experiments on the phosphorescence of organic compounds, by
+    which he was able to determine the conditions under which that
+    phenomenon was exhibited. In all the substances investigated by
+    him in which phosphorescence was introduced he found that three
+    conditions were essential to its production: (1) that oxygen
+    should be present; (2) that there should be an alkaline
+    reaction in the phosphorescing mixture&mdash;that is, a
+    reaction such as is produced on acids and vegetable coloring
+    matters by potash, soda, and the other alkalies; and (3) that
+    some kind of chemical action should take place.</p>
+
+    <p>He found, moreover, that among the organic compounds that
+    could be made to phosphoresce under these conditions were
+    nearly all the fixed and ethereal oils. With reference to the
+    phosphorescence of animals, this observation is important, for
+    it has been shown in a great many cases that a fatty substance
+    forms the main constituent in their luminous organs. This has
+    long been known to be the case in the luminous insects
+    belonging to the Lampyridæ and Elateridæ, as well as
+    <span class="pagenum"><a id="page244"></a>[pg 244]</span> in the luminous centipedes;
+       and the researches of Panceri, already referred to, on the
+       luminous organs of many marine forms have shown that it
+       holds good with regard to these also.</p>
+
+    <p>We may, therefore, conclude that substances fitted to
+    phosphoresce under the conditions determined by the experiments
+    of Radziszewski are generally, and probably universally,
+    present in the luminous organs of phosphorescent animals. Now,
+    what is to be said as to the occurrence of these conditions?
+    The access of oxygen is in all cases easy to account for, but
+    it must also be shown how the alkaline reaction is to be
+    produced. We need not expect to find in animal organisms
+    potash, soda, ammonia, and the other common alkalies; but it
+    was established by experiment that the alkaline organic
+    compounds cholin and neurin, which are present in animal
+    tissues, would also serve to bring about the phenomenon of
+    phosphorescence in the substances on which the experiments were
+    made.</p>
+
+    <p>Accordingly, it seems fair to conclude that when all these
+    conditions for the production of phosphorescence in a chemical
+    laboratory are present in animal organisms, the phenomenon,
+    when observed in these, is exactly of the same nature as that
+    which is produced artificially. By that it is meant that animal
+    phosphorescence is attended, like the artificial phenomenon, by
+    a slow chemical action, or in other words, that the
+    phosphorescent light is due to a gradual process of
+    oxidation.</p>
+
+    <p>One curious circumstance has been discovered which lends
+    still further probability to this explanation. It was mentioned
+    above that among phosphorescent plants <span class=
+    "pagenum"><a id="page245"></a>[pg 245]</span> there are several species
+       of Agaricus. Now, from one species of this genus, though not
+       indeed one of the phosphorescent species (from <i>A.
+       muscarius</i>) there has been extracted a principle called
+       <i>amanitia</i>, which is found to be identical with cholin.
+       In the light of the results derived from the investigations
+       just referred to it is reasonable to draw the conclusion
+       that, if sought for, this principle would likewise be found
+       in the phosphorescent species in which the other conditions
+       of phosphorescence are also present.</p>
+
+    <p>On this theory of the production of the phenomenon now under
+    consideration, the effect of shaking or of vital action in
+    giving rise to or intensifying the exhibition of the light is
+    accounted for by the fact that by these means fresh supplies of
+    oxygen are brought into contact with the phosphorescent
+    substance. The effect of ammonia on the light emitted by the
+    sea-slug <i>Phyllirhoë bucephala</i>, is also fully explained,
+    ammonia being one of those alkaline substances which are so
+    directly favorable to the exhibition of the phenomenon.</p>
+
+    <p>Nor is it difficult to account for the control which in some
+    cases insects appear to have over the luminosity of the
+    phosphorescent organs, exhibiting and withdrawing the light at
+    will. It is not necessary to suppose that this is an immediate
+    effect, a conversion of nerve force into light, and a
+    withdrawal of that force. The action of the creature's will may
+    be merely in maintaining or destroying the conditions under
+    which the light is manifested. It may, for example, have the
+    power of withdrawing the supply of oxygen, and this supposition
+    receives some countenance from the observation cited from Kirby
+    and Spence on the two <span class="pagenum"><a id="page246"></a>[pg 246]</span> captured glow-worms, one of
+       which withdrew its light, while the other kept it shining,
+       but while doing so had the posterior extremity of the
+       abdomen in constant motion. But the animal may also have the
+       power in another way of affecting the chemical conditions of
+       the phenomenon. It may, for example, have the power of
+       increasing or diminishing by some nervous influence the
+       supply of the necessary alkaline ingredient.</p>
+
+    <p>But if animal phosphorescence is really due to a process of
+    slow oxidation, there is one singular circumstance to be noted
+    in connection with it. Oxidation is a process that is normally
+    accompanied by the development of heat. Even where no light is
+    produced an increase of temperature regularly takes place when
+    substances are oxidized. We ought, then, to expect such a rise
+    of temperature when light is emitted by the phosphorescent
+    organs of animals. But the most careful observations have shown
+    that nothing of the kind can be detected. It was with a view to
+    test this that Panceri dissected out the luminous organs of so
+    many specimens of Pholas. He selected this mollusk because it
+    was so abundant in the neighborhood of Naples, where, his
+    experiments were made; and in making his experiments he made
+    use of a thermopile, an apparatus by which, with the aid of
+    electricity, much smaller quantities of heat can be indicated
+    than by means of the most delicate thermometer. The organs
+    remained luminous long after they were extracted, but no rise
+    in temperature whatever could be found to accompany the
+    luminosity. Many experiments upon different animals were made
+    with similar negative results by means of the
+    thermometer.</p><span class="pagenum"><a id="page247"></a>[pg 247]</span>
+
+    <p>The only explanation of this that can be given is probably
+    to be found in the fact that the chemical process ascertained
+    to go on in the phosphorescence of organic compounds on which
+    experiments were made in the laboratory is an extremely slow
+    one.</p>
+
+    <p>The so-called phosphorescence of most inorganic bodies is
+    one of a totally different nature from that exhibited in
+    organic forms. The diamond shines for a time in the dark after
+    it has been exposed to the sun; so do pieces of quartz when
+    rubbed together, and powdered fluor-spar when heated shines
+    with considerable brilliancy. Various artificial compounds,
+    such as sulphide of calcium (Canton's phosphorus, as it is
+    called from the discoverer), sulphate of barium (Bologna stone,
+    or Bologna phosphorus), sulphide of strontium, etc., after
+    being illuminated by the rays of the sun, give out in the dark
+    a beautiful phosphorescence, green, blue, violet, orange, red,
+    according to circumstances. The luminous paint which has
+    recently attracted so much attention is of the same nature. In
+    these cases what we have is either a conversion of heat rays
+    into light rays (as in the powdered fluor-spar), or the
+    absorption and giving out again of sun-rays. In the latter case
+    the phenomenon is essentially the same as fluorescence, in
+    which the dark rays of the solar spectrum beyond the violet are
+    made visible.</p>
+
+    <p>But we must now return to the other questions that have been
+    started in relation to phosphorescence in animals. There has
+    been much speculation as to the object of this light, and to
+    the purposes it serves in Nature. Probably no general answer
+    can be given to this question. It is no doubt impossible to
+    show why so many <span class="pagenum"><a id="page248"></a>[pg 248]</span> animals have been endowed
+       with this remarkable property; but we may consider some of
+       the effects which the possession of it has in different
+       cases.</p>
+
+    <p>In the first place, it will undoubtedly serve in many cases
+    to afford light to enable the animal to see by, and in the
+    Lampyridæ it would seem that the degree of luminosity is
+    related to the development of the vision. In that family,
+    according to the Rev. H.S. Gorham, the eyes are developed, as a
+    rule, in inverse proportion to the luminosity. Where there is
+    an ample supply of this kind of light the eyes are small, but
+    where the light is insignificant the eyes are large by way of
+    compensation. And moreover, where both eyes and light are
+    small, then the antennae are large and feathery, so that the
+    deficiency in the sense of sight is made up for by an unusual
+    development in the organs of touch.</p>
+
+    <p>But it is none the less certain that the presence of this
+    light cannot always be designed to serve this purpose, for many
+    of the animals so endowed are blind. The phosphorescent
+    centipedes are without eyes, like all the other members of the
+    genus (<i>Geophilus</i>) to which they belong, and probably the
+    majority of phosphorescent marine forms are likewise destitute
+    of organs of sight.</p>
+
+    <p>Another suggestion is that the light derived from these
+    marine forms, and especially from deep-sea Alcyonarians, is
+    what enables the members of the deep-sea fauna that are
+    possessed of eyes (which are always enormously enlarged) to
+    see. Such is the suggestion of Dr. Carpenter, Sir Wyville
+    Thomson, and Mr. Gwyn Jeffries; and it is possible that this
+    actually is one of the effects of the phosphorescent property.
+    But if so, it <span class="pagenum"><a id="page249"></a>[pg 249]</span> remains to inquire how the
+       forms endowed with it came to be possessed of a power useful
+       in that way to other forms, but not to themselves. According
+       to the Darwinian doctrine of development, the powers that
+       are developed in different organisms by the process of
+       natural selection are such as are useful to themselves and
+       not to others, unless incidentally.</p>
+
+    <p>This consideration has led to another suggestion, namely,
+    that the property of phosphorescence serves as a protection to
+    the forms possessing it, driving away enemies in one way or
+    another: it may be by warning them of the fact that they are
+    unpalatable food, as is believed to be the case with the colors
+    of certain brilliantly-colored caterpillars; it may be in other
+    ways. In Kirby and Spence one case is recorded in which the
+    phosphorescence of the common phosphorescent centipede
+    (<i>Geophilus electricus</i>) was actually seen apparently to
+    serve as a means of defence against an enemy. "Mr. Shepherd,"
+    says that authority, "once noticed a scarabeus running round
+    the last-mentioned insect when shining, as if wishing, but
+    afraid to attack it." In the case of the jelly-fishes, it has
+    been pointed out that their well-known urticating or stinging
+    powers would make them at least unpleasant, if not dangerous,
+    food for fishes; and that consequently the luminosity by which
+    so many of them are characterized at night may serve at once as
+    a warning to predatory fishes and as a protection to
+    themselves. The experience of the unpleasant properties of many
+    phosphorescent animals may likewise have taught fishes to avoid
+    all forms possessing this attribute, even though many of them
+    might be quite harmless.</p><span class="pagenum"><a name=
+    "page250"
+       id="page250"></a>[pg 250]</span>
+
+    <p>Lastly, it has been suggested that the phosphorescence in
+    the female glow-worm may be designed to attract the male; and
+    that it will actually have this effect may readily be taken for
+    granted. Observation shows that the male glow-worm is very apt
+    to be attracted by a light. Gilbert White of Selborne mentions
+    that they, attracted by the light of the candles, came into his
+    parlor. Another observer states that by the same light he
+    captured as many as forty male glow-worms in one night.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/250.png"><img width="500"
+             src="images/250.png"
+             alt="glow-worms by candlelight"></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="page251"></a>[pg 251]</span>
+
+    <h2>COMETS</h2>
+
+    <h4>(<span class="sc">From Marvels of the Heavens</span>.)</h4>
+
+    <h3><span class="sc">By</span> CAMILLE FLAMMARION.</h3>
+    <hr class="short">
+
+    <div class="poem">
+        <div class="stanza">
+            <p>"Je viens vous annoncer une grande nouvelle:</p>
+
+            <p>Nous l'avons, en dormant, madame, échappé belle.</p>
+
+            <p>Un monde près de nous a passé tout du long,</p>
+
+            <p>Est chu tout au travers de notre tourbillon;</p>
+
+            <p>Et s'il eût en chemin rencontré notre terre,</p>
+
+            <p>Elle eût été brisée en morceaux comme verre."</p>
+
+            <p class="i30"><span class="sc">Molière</span>.</p>
+        </div>
+    </div>
+
+    <div class="figleft"
+         style="width:225px;">
+        <a href="images/251.png"><img width="225"
+             src="images/251.png"
+             alt="comet"></a>
+    </div>
+
+    <p>This announcement of Trissontin's to Philaminte, who begins
+    the parody on the fears caused by the appearance of comets,
+    would not have been a parody four or five centuries ago. These
+    tailed bodies, which suddenly come to light up the heavens,
+    were for long regarded with terror, like so many warning signs
+    of divine wrath. Men have always thought themselves much more
+    important than they really are in the universal order; they
+    have had the vanity to pretend that the whole creation was made
+    for them, whilst in reality the whole creation does not suspect
+    their existence. The Earth we inhabit is only one of the
+    smallest <span class="pagenum"><a id="page252"></a>[pg 252]</span> worlds; and therefore it
+       can scarcely be for it alone that all the wonders of the
+       heavens, of which the immense majority remains hidden from
+       it, were created. In this disposition of man to see in
+       himself the centre and the end of everything, it was easy
+       indeed to consider the steps of nature as unfolded in his
+       favor; and if some unusual phenomenon presented itself, it
+       was considered to be without doubt a warning from Heaven. If
+       these illusions had had no other result than the
+       amelioration of the more timorous of the community one would
+       regret these ages of ignorance; but not only were these
+       fancied warnings of no use, seeing that once the danger
+       passed, man returned to his former state; but they also kept
+       up among people imaginary terrors, and revived the fatal
+       resolutions caused by the fear of the end of the world.</p>
+
+    <p>When one fancies the world is about to end,&mdash;and this
+    has been believed for more than a thousand years,&mdash;no
+    solicitude is felt in the work of improving this world; and, by
+    the indifference or disdain into which one falls, periods of
+    famine and general misery are induced which at certain times
+    have overtaken our community. Why use the wealth of a world
+    which is going to perish? Why work, be instructed, or rise in
+    the progress of the sciences or arts? Much better to forget the
+    world, and absorb one's self in the barren contemplation of an
+    unknown life. It is thus that ages of ignorance weigh on man,
+    and thrust him further and further into darkness, while Science
+    makes known by its influence on the whole community, its great
+    value, and the magnitude of its aim.</p>
+
+    <p>The history of a comet would be an instructive
+          <span class="pagenum"><a id="page253"></a>[pg 253]</span> episode of the great
+       history of the heavens. In it could be brought together the
+       description of the progressive movement of human thought, as
+       well as the astronomical theory of these extraordinary
+       bodies. Let us take, for example, one of the most memorable
+       and best-known comets, and give an outline of its successive
+       passages near the Earth. Like the planetary worlds, Comets
+       belong to the solar system, and are subject to the rule of
+       the Star King. It is the universal law of gravitation which
+       guides their path; solar attraction governs them, as it
+       governs the movement of the planets and the small
+       satellites. The chief point of difference between them and
+       the planets is, that their orbits are very elongated; and,
+       instead of being nearly circular, they take the elliptical
+       form. In consequence of the nature of these orbits, the same
+       comet may approach very near the Sun, and afterwards travel
+       from it to immense distances. Thus, the period of the Comet
+       of 1680 has been estimated at three thousand years. It
+       approaches the Sun, so as to be nearer to it than our Moon
+       is to us, whilst it recedes to a distance 853 times greater
+       than the distance of the Earth from the Sun. On the 17th of
+       December, 1680, it was at its perihelion&mdash;that is, at
+       its greatest proximity to the Sun; it is now continuing its
+       path beyond the Neptunian orbit. Its velocity varies
+       according to its distance from the solar body. At its
+       perihelion it travels thousands of leagues per minute; at
+       its aphelion it does not pass over more than a few yards.
+       Its proximity to the Sun in its passage near that body
+       caused Newton to think that it received a heat twenty-eight
+       thousand times greater than that we experience at the summer
+       <span class="pagenum"><a id="page254"></a>[pg 254]</span> solstice; and that this
+       heat being two thousand times greater than that of red-hot
+       iron, an iron globe of the same dimensions would be fifty
+       thousand years entirely losing its heat. Newton added that
+       in the end comets will approach so near the Sun that they
+       will not be able to escape the preponderance of its
+       attraction, and that they will fall one after the other into
+       this brilliant body, thus keeping up the heat which it
+       perpetually pours out into space. Such is the deplorable end
+       assigned to comets by the author of the "Principia," an end
+       which makes De la Brétonne say to Rétif: "An immense comet,
+       already larger than Jupiter, was again increased in its path
+       by being blended with six other dying comets. Thus displaced
+       from its ordinary route by these slight shocks, it did not
+       pursue its true elliptical orbit; so that the unfortunate
+       thing was precipitated into the devouring centre of the
+       Sun." "It is said," added he, "that the poor comet, thus
+       burned alive, sent forth dreadful cries!"</p>
+
+    <div class="figcenter"
+         style="width:300px;">
+        <a href="images/281.jpg"><img width="300"
+             src="images/281sm.jpg"
+             alt="A COMET"></a><br>
+        A COMET
+    </div>
+
+    <p>It will be interesting, then, in a double point of view, to
+    follow a comet in its different passages in sight of the Earth.
+    Let us take the most important in astronomical
+    history&mdash;the one whose orbit has been calculated by Edmund
+    Halley, and which was named after him. It was in 1682 that this
+    comet appeared in its greatest brilliancy, accompanied with a
+    tail which did not measure less than thirty-two millions of
+    miles. By the observation of the path which it described in the
+    heavens, and the time it occupied in describing it, this
+    astronomer calculated its orbit, and recognized that the comet
+    was the same as that which was admired in 1531 and 1607, and
+    which ought to have reappeared in <span class=
+       "pagenum"><a id="page255"></a>[pg 255]</span> 1759. Never did scientific
+       prediction excite a more lively interest. The comet returned
+       at the appointed time; and on the 12th of March, 1759,
+       reached its perihelion. Since the year 12 before the
+       Christian era, it had presented itself twenty-four times to
+       the Earth. It was principally from the astronomical annals
+       of China that it was possible to follow it up to this
+       period.</p>
+
+    <p>Its first memorable appearance in the history of France is
+    that of 837, in the reign of Louis le Débonnaire. An anonymous
+    writer of chronicles of that time, named "The Astronomer," gave
+    the following details of this appearance, relative to the
+    influence of the comet on the imperial imagination:</p>
+
+    <p>"During the holy days of the solemnization of Easter, a
+    phenomenon ever fatal, and of gloomy foreboding, appeared in
+    the heavens. As soon as the Emperor, who paid attention to
+    these phenomena, received the first announcement of it, he gave
+    himself no rest until he had called a certain learned man and
+    myself before him. As soon as I arrived, he anxiously asked me
+    what I thought of such a sign; I asked time of him, in order to
+    consider the aspects of the stars, and to discover the truth by
+    their means, promising to acquaint him on the morrow; but the
+    Emperor, persuaded that I wished to gain time, which was true,
+    in order not to be obliged to announce anything fatal to him,
+    said to me: 'Go on the terrace of the palace and return at once
+    to tell me what you have seen, for I did not see this star last
+    evening, and you did not point it out to me; but I know that it
+    is a comet; tell me what you think it announces to me.' Then
+    scarcely <span class="pagenum"><a id="page256"></a>[pg 256]</span> allowing me time to say a
+       word, he added: 'There is still another thing you keep back;
+       it is that a change of reign and the death of a prince are
+       announced by this sign.' And as I advanced the testimony of
+       the prophet, who said: 'Fear not the signs of the heavens as
+       the nations fear them,' the prince with his grand nature,
+       and the wisdom which never forsook him, said, 'We must not
+       only fear Him who has created both us and this star. But as
+       this phenomenon may refer to us, let us acknowledge it as a
+       warning from Heaven."</p>
+
+    <p>Louis le Débonnaire gave himself and his court to fasting
+    and prayer, and built churches and monasteries. He died three
+    years later, in 840, and historians have profited by this
+    slight coincidence to prove that the appearance of the comet
+    was a harbinger of death. The historian, Raoul Glader, added
+    later: "These phenomena of the universe are never presented to
+    man without surely announcing some wonderful and terrible
+    event."</p>
+
+    <p>Halley's comet again appeared in April, 1066, at the moment
+    when William the Conqueror invaded England. It was pretended
+    that it had the greatest influence on the fate of the battle of
+    Hastings, which delivered over the country to the Normans.</p>
+
+    <p>A contemporary poet, alluding probably to the English diadem
+    with which William was crowned, had proclaimed in one place,
+    "that the comet had been more favorable to William than nature
+    had been to Caesar; the latter had no hair, but William had
+    received some from the comet." A monk of Malmesbury
+    apostrophized the comet in these terms: "Here thou art again,
+    thou cause of the tears of many <span class=
+       "pagenum"><a id="page257"></a>[pg 257]</span> mothers! It is long since I
+       have seen thee, but I see thee now, more terrible than ever;
+       thou threatenest my country with complete ruin!"</p>
+
+    <p>In 1455, the same comet made a more memorable appearance
+    still. The Turks and Christians were at war, the West and the
+    East seemed armed from head to foot&mdash;on the point of
+    annihilating each other. The crusade undertaken by Pope
+    Calixtus III. against the invading Saracens, was waged with
+    redoubled ardor on the sudden appearance of the star with the
+    flaming tail. Mahomet II. took Constantinople by storm, and
+    raised the siege of Belgrade. But the Pope having put aside
+    both the curse of the comet, and the abominable designs of the
+    Mussulmans, the Christians gained the battle, and vanquished
+    their enemies in a bloody fight. The <i>Angelus</i> to the
+    sound of bells dates from these ordinances of Calixtus III.
+    referring to the comet.</p>
+
+    <p>In his poem on astronomy, Daru, of the French Academy,
+    describes this episode in eloquent terms:</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p class="i2">"Un autre Mahomet a-t-il d'un bras
+            puissant</p>
+
+            <p class="i2">Aux murs de Constantine arboré le
+            croissant:</p>
+
+            <p class="i2">Le Danube étonné se trouble au bruit des
+            armes,</p>
+
+            <p class="i2">La Grèce est dans les fers, l'Europe est
+            en alarmes;</p>
+
+            <p class="i2">Et pour comble d'horreur, l'astre au
+            visage ardent</p>
+
+            <p class="i2">De ses ailes de feu va couvrir
+            l'Occident.</p>
+
+            <p class="i2">Au pied de ses autels, qu'il ne saurait
+            défendre,</p>
+
+            <p class="i2">Calixte, l'oeil en pleurs, le front
+            convert de cendre,</p>
+
+            <p class="i2">Conjure la comète, objet de tant
+            d'effroi:</p>
+
+            <p class="i2">Regarde vers les cieux, pontife, et
+            lève-toi!</p>
+
+            <p class="i2">L'astre poursuit sa course, et le fer
+            d'Huniade</p>
+
+            <p class="i2">Arrête le vainqueur, qui tombe sous
+            Belgrade.</p>
+
+            <p class="i2">Dans les cieux cependant le globe
+            suspendu,</p>
+
+            <p class="i2">Par la loi générale à jamais
+            retenu,</p><span class="pagenum"><a id="page258"></a>[pg 258]</span>
+
+            <p class="i2">Ignore les terreurs, l'existence de
+            Rome,</p>
+
+            <p class="i2">Et la Terre peut-être, et jusqu'au nom de
+            l'homme,</p>
+
+            <p class="i2">De l'homme, être crédule, atome
+            ambitieux,</p>
+
+            <p class="i2">Qui tremble sous un prêtre et qui lit
+            dans les cieux."</p>
+        </div>
+    </div>
+
+    <p>This ancient comet witnessed many revolutions in human
+    history, at each of its appearances, even in its later ones, in
+    1682, 1759, 1835; it was also presented to the Earth under the
+    most diverse aspects, passing through a great variety of forms,
+    from the appearance of a curved sabre, as in 1456, to that of a
+    misty head, as in its last visit. Moreover, this is not an
+    exception to the general rule, for these mysterious stars have
+    had the gift of exercising a power on the imagination which
+    plunged it in ecstasy or trouble. Swords of fire, bloody
+    crosses, flaming daggers, spears, dragons, fish, and other
+    appearances of the same kind, were given to them in the middle
+    ages and the Renaissance.</p>
+
+    <p>Comets like those of 1577 appear, moreover, to justify by
+    their strange form the titles with which they are generally
+    greeted. The most serious writers were not free from this
+    terror. Thus, in a chapter on celestial monsters, the
+    celebrated surgeon, Ambroise Paré, described the comet of 1528
+    under the most vivid and frightful colors: "This comet was so
+    horrible and dreadful that it engendered such great terror to
+    the people, that they died, some with fear, others with
+    illness. It appeared to be of immense length, and of blood
+    color; at its head was seen the figure of a curved arm, holding
+    a large sword in the hand as if it wished to strike. At the
+    point of the sword there were three stars, and on either side
+    was seen a great number of hatchets, knives, and swords covered
+    with blood, <span class="pagenum"><a id="page259"></a>[pg 259]</span> amongst which were numerous
+       hideous human faces, with bristling beards and hair."</p>
+
+    <p>The imagination has good eyes when it exerts itself. The
+    great and strange variety of cometary aspects is described with
+    exactitude by Father Souciet in his Latin poem on comets. "Most
+    of them," says he, "shine with fires interlaced like thick
+    hair, and from this they have taken the name of comets. One
+    draws after it the twisted folds of a long tail; another
+    appears to have a white and bushy beard; this one throws a
+    glimmer similar to that of a lamp burning during the night;
+    that one, O Titan! represents thy resplendent face; and this
+    other, O Phoebe! the form of thy nascent horns. There are some
+    which bristle with twisted serpents. Shall I speak of those
+    armies which have sometimes appeared in the air? of those
+    clouds which follow as it were along a circle, or which
+    resemble the head of Medusa? Have there not often been seen
+    figures of men or savage animals?</p>
+
+    <p>"Often, in the gloom of night, lighted up by these sad
+    fires, the horrible sound of arms is heard, the clashing of
+    swords which meet in the clouds, the ether furiously resounding
+    with fearful din which crush the people with terror. All comets
+    have a melancholy light, but they have not all the same color.
+    Some have a leaden color; others that of flame or brass. The
+    fires of some have the redness of blood; others resemble the
+    brightness of silver. Some again are azure; others have the
+    dark and pale color of iron. These differences come from the
+    diversity of the vapors which surround them, or from the
+    different manner in which they receive the Sun's rays. Do you
+    not see in our fires, that various <span class=
+    "pagenum"><a id="page260"></a>[pg 260]</span> kinds of wood produce
+       different colors? Pines and firs give a flame mixed with
+       thick smoke, and throw out little light. That which rises
+       from sulphur and thick bitumen is bluish. Lighted straw
+       gives out sparks of a reddish color. The large olive,
+       laurel, ash of Parnassus, etc., trees which always retain
+       their sap, throw a whitish light similar to that of a lamp.
+       Thus, comets whose fires are formed of different materials,
+       each take and preserve a color which is peculiar to
+       them."</p>
+
+    <p>Instead of being a cause of fear and terror, the variety and
+    variability of the aspect of comets ought rather to indicate to
+    us the harmlessness of their nature.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/260.png"><img width="500"
+             src="images/260.png"
+             alt="a comet"></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="page261"></a>[pg 261]</span>
+
+    <h2>THE TOTAL SOLAR ECLIPSE OF 1883</h2>
+
+    <h3><i>AN ASTRONOMERS VOYAGE TO FAIRY-LAND.</i></h3>
+
+    <h4>(<span class="sc">From The Atlantic Monthly, May,
+    1890.</span>)</h4>
+
+    <h3><span class="sc">By</span> PROF. E.S. HOLDEN.</h3>
+    <hr class="short">
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/261.png"><img width="200"
+             src="images/261.png"
+             alt="Solar Eclipse"></a>
+    </div>
+
+    <p>In 1883 calculations showed that a solar eclipse of
+    unusually long duration (5 minutes, 20 seconds) would occur in
+    the South Pacific Ocean. The track of the eclipse lay south of
+    the equator, but north of Tahiti. There were in fact only two
+    dots of coral islands on the charts in the line of totality,
+    Caroline Island, and one hundred and fifty miles west Flint
+    Island (longitude 150 west, latitude 10 south). Almost nothing
+    was known of either of these minute points. The station of the
+    party under my charge (sent out by the United States government
+    under the direction of the National Academy of Sciences) was to
+    be Caroline Islands.</p>
+
+    <p>Every inch of that island (seven miles long, a mile or so
+    broad) is familiar now; but it is almost ludicrous to recollect
+    with what anxiety we pored over the hydrographic charts and
+    sailing instructions of the various <span class=
+    "pagenum"><a id="page262"></a>[pg 262]</span> nations, to find some
+       information, however scanty, about the spot which was to be
+       our home for nearly a month. All that was known was that
+       this island had formerly been occupied as a guano station.
+       There was a landing <i>then</i>.</p>
+
+    <p>After the <i>personnel</i> of the party had been decided on,
+    there were the preparations for its subsistence to be looked
+    out for. How to feed seventeen men for twenty-one days?
+    Fortunately the provisions that we took, and the fresh fish
+    caught for us by the natives, just sufficed to carry us through
+    with comfort and with health.</p>
+
+    <p>In March of 1883 we sailed from New York, and about the same
+    time a French expedition left Europe bound for the same spot.
+    From New York to Panama, from Panama to Lima, were our first
+    steps. Here we joined the United States steamship Hartford,
+    Admiral Farragut's flagship, and the next day set sail for our
+    destined port,&mdash;if a coral reef surrounded by a raging
+    surf can be called a port. About the same time a party of
+    French observers under Monsieur Janssen, of the Paris Academy
+    of Sciences, left Panama in the <i>Eclaireur</i>.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/262.png"><img width="500"
+             src="images/262.png"
+             alt=
+           "BIRD'S EYE VIEW OF THE CAROLINE ISLANDS."></a><br>
+        BIRD'S EYE VIEW OF THE CAROLINE ISLANDS.
+    </div>
+
+    <p>It was an ocean race of four thousand miles due
+          <span class="pagenum"><a id="page263"></a>[pg 263]</span> west. The station Caroline
+       Islands was supposed to be more desirable than Flint Island.
+       Admiral Wilkes's expedition had lain off the latter several
+       days without being able to land on account of the tremendous
+       surf, so that it was eminently desirable to "beat the
+       Frenchman," as the sailors put it. With this end in view our
+       party had secured (through a member of the National Academy
+       in Washington) the verbal promise of the proper official of
+       the Navy Department that the Hartford's orders should read
+       "to burn coal as necessary." The last obstacle to success
+       was thus removed. We were all prepared, and now the ship
+       would take us speedily to our station.</p>
+
+    <p>Imagine our feelings the next day after leaving Callao, when
+    the commanding officer of the Hartford opened his sealed
+    orders. They read (dated Washington, in February), "To arrive
+    at Caroline Islands (in April) with full coal-bunkers!"</p>
+
+    <p>Officialism could go no further. Here was an expedition sent
+    on a slow-sailing ship directly through the regions of calms
+    for four thousand miles. It was of no possible use to send the
+    expedition at all unless it arrived in time. And here were our
+    orders "to arrive with full coal-bunkers."</p>
+
+    <p>Fortunately we had unheard-of good-luck. The trade-wind blew
+    for us as it did for the Ancient Mariner, and we sped along the
+    parallel of 12° south at the rate of one hundred and fifty
+    miles a day under sail, while the <i>Eclaireur</i> was steaming
+    for thirty days a little nearer the equator in a dead calm. We
+    arrived off the island just in time, with not a day to spare.
+    It was a narrow escape, and a warning to all of us never to
+    sail again <span class="pagenum"><a id="page264"></a>[pg 264]</span> under sealed orders unless
+       we knew what was under the seal.</p>
+
+    <p>Here we were, then, lying off the island and scanning its
+    sparse crown of cocoanut palms, looking for a French flag among
+    their wavy tufts. There was none in sight. We were the winners
+    in the long race. Directly a whale-boat was lowered, and rowed
+    around the white fringe of tremendous surf that broke
+    ceaselessly against the vertical wall of coral rock. There was
+    just one narrow place where the waves rolled into a sort of
+    cleft and did not break. Here was the "landing," then.</p>
+
+    <p>Landing was an acrobatic feat. In you went on the crest of a
+    wave, pointing for the place where the blue seas did not break
+    into white. An instant after, you were in the quiet water
+    inside of the surf. Jump out everybody and hold the boat! Then
+    it was pick up the various instruments, and carry them for a
+    quarter of a mile to high-water mark and beyond, over the sharp
+    points of the reef.</p>
+
+    <p>In one night we were fairly settled; in another the Hartford
+    had sailed away, leaving us in our fairy paradise, where the
+    corals and the fish were of all the brilliant hues of the
+    rainbow, and where the whiteness of the sand, the emerald of
+    the lagoon, and the turquoise of the ocean made a picture of
+    color and form never to be forgotten.</p>
+
+    <p>But where are the Frenchmen? The next morning there is the
+    <i>Eclaireur</i> lying a mile or so out, and there is a boat
+    with the bo'sun&mdash;<i>maître d'équipage</i>&mdash;pulling
+    towards the surf. I wade out to the brink. He
+    halloes:</p><span class="pagenum"><a id="page265"></a>[pg 265]</span>
+
+    <p>"Where is the landing, then?"</p>
+
+    <p>"<i>Mais ici</i>"&mdash;Right here,&mdash;I say.</p>
+
+    <p>"Yes, that's all very well for <i>persons</i>, but where do
+    you land <i>les bagages</i>?"</p>
+
+    <p>"<i>Mais ici</i>" I say again, and he says,
+    "<i>Diable!</i>"</p>
+
+    <p>But all the same he lands both persons and baggage in a
+    neat, sailor-like way. In a couple of days our two parties of
+    fifty persons had taken possession of this fairy isle.
+    Observatories go up, telescopes, spectroscopes, photographic
+    cameras are pointed and adjusted. The eventful day arrives.
+    Everything is successful. Then comes the Hartford and takes us
+    away, and a few days later comes the <i>Eclaireur</i>, and the
+    Frenchmen are gone. The little island is left there, abandoned
+    to the five natives who tend the sickly plantation of
+    cocoa-palms, and live from year to year with no incident but
+    the annual visit of "the blig" (Kanaka for brig), which brings
+    their store of ship biscuit and molasses.</p>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/265.png"><img width="600"
+             src="images/265.png"
+             alt="'OBSERVATORIES GO UP.'"></a><br>
+        "OBSERVATORIES GO UP."
+    </div>
+
+    <p>Think of their stupendous experience! For years and years
+    they have lived like that in the marvellous, continuous charm
+    of the silent island. The "blig" <span class=
+       "pagenum"><a id="page266"></a>[pg 266]</span> had come and gone away this
+       year, and there will be no more disturbance and discord for
+       a twelve-month longer.</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p>"Surely, surely, slumber is more sweet than toil,
+            the shore</p>
+
+            <p>Than labor in the deep mid-ocean, wind, and wave,
+            and oar,</p>
+
+            <p>Then rest ye, brother mariners, we will not wander
+            more!"</p>
+        </div>
+    </div>
+
+    <p>Not so! for here comes a great warship out of the East under
+    a press of canvas. What event is this? See! she clews up her
+    light sails and fires an eleven-inch gun! One of those guns of
+    Mobile Bay. Then swarms out the starboard watch, one hundred
+    and sixty strong, and a fleet of boats brings ashore these pale
+    astronomers with those useless tubes that they point at the sky
+    every night. But there are useful things too; cooking-stoves,
+    and lumber, and bricks.</p>
+
+    <p>What is all this? No sooner are these established than comes
+    another ship and fires its gun! and another set of hardy
+    sailormen pours out, and here is another party of madmen with
+    tubes,&mdash;yes, and with cooking-stoves and lumber, too. Then
+    comes the crowning, stupendous, and unspeakable event. The
+    whole sun is hidden and the heavens are lighted up with pearly
+    streamers! In the name of all the Polynesian gods, what is the
+    meaning of all this?</p>
+
+    <p>And then in a few days all these are gone. All the madmen.
+    They have taken away the useless tubes, but they have left
+    their houses standing. Their splendid, priceless, precious
+    cook-stoves are here. See! here is a frying-pan! here are empty
+    tin cans! and a keg of nails! They must have forgotten all
+    this, madmen as they are!</p><span class="pagenum"><a name=
+    "page267"
+       id="page267"></a>[pg 267]</span>
+
+    <p>And the little island sinks back to its quiet and its calm.
+    The lagoon lies placid like a mirror. The slow sea breaks
+    eternally on the outer reef. The white clouds sail over day by
+    day. The seabirds come back to their haunts,&mdash;the fierce
+    man-of-war birds, the gentle, soft-eyed tern. But we, whose
+    island home was thus invaded&mdash;are we the same? Was this a
+    dream? Will it happen again next year? every year? What indeed
+    was it that happened,&mdash;or in fact, did it happen at all?
+    Is it not a dream, indeed?</p>
+
+    <p>If we left those peaceful Kanakas to their dream, we
+    Americans have brought ours away with us. Who will forget it?
+    Which of us does not wish to be in that peaceful fairyland once
+    more? That is the personal longing. But we have all come back,
+    each one with his note-books full; and in a few weeks the
+    stimulus of accustomed habit has taken possession of us again.
+    Right and wrong are again determined by "municipal sanctions."
+    We have become useful citizens once more. Perhaps it is just as
+    well. We should have been poor poets, and we do not forget. So
+    ends the astronomer's voyage to fairyland.</p>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/267.png"><img width="400"
+             src="images/267.png"
+             alt="Peaceful Island"></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="page268"></a>[pg 268]</span>
+
+    <h2>HALOS&mdash;PARHELIA&mdash;THE SPECTRE OF THE BROCKEN,
+    ETC</h2>
+
+    <h4>(<span class="sc">From The Atmosphere.</span>)</h4>
+
+    <h3><span class="sc">By</span> CAMILLE FLAMMARION.</h3>
+    <hr class="short">
+
+    <div class="figleft"
+         style="width:231px;">
+        <a href="images/268.png"><img width="231"
+             src="images/268.png"
+             alt="Rainbow"></a>
+    </div>
+
+    <p>Treatises on meteorology have not, up to the present day,
+    classified with sufficient regularity the divers optical
+    phenomena of the air. Some of these phenomena have, however,
+    been seen but rarely, and have not been sufficiently studied to
+    admit of their classification. We have examined the common
+    phenomenon of the rainbow and we have seen that it is due to
+    the refraction and reflection of light on drops of water, and
+    that it is seen upon the opposite side of the sky to the sun in
+    day-time, or the moon at night. We are now about to consider an
+    order of phenomena which are of rarer occurrence, but which
+    have this property in common with the rainbow, viz., that they
+    take place also upon the side of the sky opposite to the sun.
+    These different optical effects are <span class=
+    "pagenum"><a id="page269"></a>[pg 269]</span> classed together under the
+       name of <i>anthelia</i> (from Greek, opposite to, and Greek,
+       the sun). The optical phenomena which occur on the same side
+       as, or around the sun, such as halos, parhelia, etc., will
+       be dealt with later on.</p>
+
+    <p>Before coming to the anthelia, properly so called, or to the
+    colored rings which appear around a shadow, it is as well first
+    to note the effects produced on the clouds and mists that are
+    facing the sun when it rises or sets.</p>
+
+    <p>Upon high mountains, the shadow of the mountain is often
+    seen thrown either upon the surface of the lower mists or upon
+    the neighboring mountains, and projected opposite to the sun
+    almost horizontally. I once saw the shadow of the Righi very
+    distinctly traced upon Mount Pilate, which is situated to the
+    west of the Righi, on the other side of the Lake of Lucerne.
+    This phenomenon occurs a few minutes after sunrise, and the
+    triangular form of Righi is delineated in a shape very easy to
+    recognize.</p>
+
+    <p>The shadow of Mont Blanc is discerned more easily at sunset.
+    MM. Bravais and Martins, in one of their scientific ascents,
+    noticed it under specially favorable circumstances, the shadow
+    being thrown upon the snow-covered mountains, and gradually
+    rising in the atmosphere until it reached a height of 1°, still
+    remaining quite visible. The air above the cone of the shadow
+    was tinted with that rosy purple which is seen, in a fine
+    sunset, coloring the lofty peaks. "Imagine," says Bravais, "the
+    other mountains also projecting, at the same moment, their
+    shadows into the atmosphere, the lower parts dark and slightly
+    greenish, and above each of these shadows the rosy surface,
+    with the deeper rose <span class="pagenum"><a id="page270"></a>[pg 270]</span> of the belt which separates
+       it from them; add to this the regular contour of the cones
+       of the shadow, principally at the upper edge, and lastly,
+       the laws of perspective causing all these lines to converge
+       the one to the other toward the very summit of the shadow of
+       Mont Blanc; that is to say, to the point of the sky where
+       the shadows of our own selves were; and even then one will
+       have but a faint idea of the richness of the meteorological
+       phenomenon displayed before our eyes for a few instants. It
+       seemed as though an invisible being was seated upon a throne
+       surrounded by fire, and that angels with glittering wings
+       were kneeling before him in adoration."</p>
+
+    <p>Among the natural phenomena which now attract our attention,
+    but fail to excite our surprise, there are some which possess
+    the characteristics of a supernatural intervention. The names
+    which they have received still bear witness to the terror which
+    they once inspired; and even to-day, when science has stripped
+    them of their marvellous origin, and explained the causes of
+    their production, these phenomena have retained a part of their
+    primitive importance, and are welcomed by the <i>savant</i>
+    with as much interest as when they were attributed to divine
+    agency. Out of a large and very diverse number, I will first
+    select the <i>Spectre of the Brocken</i>.</p>
+
+    <p>The Brocken is the highest mountain in the picturesque Hartz
+    chain, running through Hanover, being three hundred and thirty
+    feet above the level of the sea.</p>
+
+    <p>One of the best descriptions of this phenomenon is given by
+    the traveller Hane, who witnessed it on the 23d of May, 1797.
+    After having ascended no less than <span class=
+    "pagenum"><a id="page271"></a>[pg 271]</span> thirty miles to the summit,
+       he had the good fortune at last to contemplate the object of
+       his curiosity. The sun rose at about four o'clock, the
+       weather being fine, and the wind driving off to the west the
+       transparent vapors which had not yet had time to be
+       condensed into clouds. About a quarter-past four, Hane saw
+       in this direction a human figure of enormous dimensions. A
+       gust of wind nearly blowing off his hat at that moment, he
+       raised his hand to secure it, and the colossal figure
+       imitated his action. Hane, noticing this, at once made a
+       stooping movement, and this was also reproduced by the
+       spectre. He then called another person to him, and placing
+       themselves in the very spot where the apparition was first
+       seen, the pair kept their eyes fixed on the Achtermannshohe,
+       but saw nothing. After a short interval, however, two
+       colossal figures appeared, which repeated the gestures made
+       by them, and then disappeared.</p>
+
+    <p>Some few years ago, in the summer of 1862, a French artist,
+    M. Stroobant, witnessed and carefully sketched this phenomenon,
+    which is drawn in full-page illustration, opposite p. 272. He
+    had slept at the inn of the Brocken, and rising at two in the
+    morning, he repaired to the plateau upon the summit in the
+    company of a guide. They reached the highest point just as the
+    first glimmer of the rising sun enabled them to distinguish
+    clearly objects at a great distance. To use M. Stroobant's own
+    words, "My guide, who had for some time appeared to be walking
+    in search of something, suddenly led me to an elevation whence
+    I had the singular privilege of contemplating for a few
+    instants the magnificent effect of mirage, which is termed the
+    Spectre <span class="pagenum"><a id="page272"></a>[pg 272]</span> of the Brocken. The
+       appearance is most striking. A thick mist, which seemed to
+       emerge from the clouds like an immense curtain, suddenly
+       rose to the west of the mountain, a rainbow was formed, then
+       certain indistinct shapes were delineated. First, the large
+       tower of the inn was reproduced upon a gigantic scale; after
+       that we saw our two selves in a more vague and less exact
+       shape, and these shadows were in each instance surrounded by
+       the colors of the rainbow, which served as a frame to this
+       fairy picture. Some tourists who were staying at the inn had
+       seen the sun rise from their windows, but no one had
+       witnessed the magnificent spectacle which had taken place on
+       the other side of the mountain."</p>
+
+    <p>Sometimes these spectres are surrounded by colored
+    concentric arcs. Since the beginning of the present century,
+    treatises on meteorology designate, under the name of the
+    <i>Ulloa circle</i>, the pale external arch which surrounds the
+    phenomenon, and this same circle has sometimes been called the
+    "white rainbow." But it is not formed at the same angular
+    distance as the rainbow, and, although pale, it often envelops
+    a series of interior colored arcs.</p>
+
+    <div class="figcenter"
+         style="width:300px;">
+        <a href="images/303.jpg"><img width="300"
+             src="images/303sm.jpg"
+             alt="'THE SPECTRE OF THE BROCKEN'"></a><br>
+        "THE SPECTRE OF THE BROCKEN"
+    </div>
+
+    <p>Ulloa, being in company with six fellow-travellers upon the
+    Pambamarca at daybreak one morning, observed that the summit of
+    the mountain was entirely covered with thick clouds, and that
+    the sun, when it rose, dissipated them, leaving only in their
+    stead light vapors, which it was almost impossible to
+    distinguish. Suddenly, in the opposite direction to where the
+    sun was rising, "each of the travellers beheld, at about
+    seventy feet from where he was standing, his own
+          <span class="pagenum"><a id="page273"></a>[pg 273]</span> image reflected in the air
+       as in a mirror. The image was in the centre of three
+       rainbows of different colors, and surrounded at a certain
+       distance by a fourth bow with only one color. The inside
+       color of each bow was carnation or red, the next shade was
+       violet, the third yellow, the fourth straw color, the last
+       green. All these bows were perpendicular to the horizon;
+       they moved in the direction of, and followed, the image of
+       the person they enveloped as with a glory." The most
+       remarkable point was that, although the seven spectators
+       were standing in a group, each person only saw the
+       phenomenon in regard to his own person, and was disposed to
+       disbelieve that it was repeated in respect to his
+       companions. The extent of the bows increased continually and
+       in proportion to the height of the sun; at the same time
+       their colors faded away, the spectre <span class=
+       "pagenum"><a id="page274"></a>[pg 274]</span> became paler and more
+       indistinct, and finally the phenomenon disappeared
+       altogether. At the first appearance the shape of the bows
+       was oval, but toward the end they became quite circular. The
+       same apparition was observed in the polar regions by
+       Scoresby, and described by him. He states that the
+       phenomenon appears whenever there is mist and at the same
+       time shining sun. In the polar seas, whenever a rather thick
+       mist rises over the ocean, an observer, placed on the mast,
+       sees one or several circles upon the mist.</p>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/273.png"><img width="600"
+             src="images/273.png"
+             alt="THE ULLOA CIRCLE."></a><br>
+        THE ULLOA CIRCLE.
+    </div>
+
+    <p>These circles are concentric, and their common centre is in
+    the straight line joining the eye of the observer to the sun,
+    and extended from the sun toward the mist. The number of
+    circles varies from one to five; they are particularly numerous
+    and well colored when the sun is very brilliant and the mist
+    thick and low. On July 23, 1821, Scoresby saw four concentric
+    circles around his head. The colors of the first and of the
+    second were very well defined; those of the third, only visible
+    at intervals, were very faint, and the fourth only showed a
+    slight greenish tint.</p>
+
+    <p>The meteorologist Kaemtz has often observed the same fact in
+    the Alps. Whenever this shadow was projected upon a cloud, his
+    head appeared surrounded by a luminous aureola.</p>
+
+    <p>To what action of light is this phenomenon due? Bouguer is
+    of opinion that it must be attributed to the passage of light
+    through icy particles. Such, also, is the opinion of De
+    Saussure, Scoresby, and other meteorologists.</p>
+
+    <p>In regard to the mountains, as we cannot assure ourselves
+    directly of the fact by entering the clouds, we
+          <span class="pagenum"><a id="page275"></a>[pg 275]</span> are reduced to conjecture.
+       The aerostat traversing the clouds completely, and passing
+       by the very point where the apparition is seen, affords one
+       an opportunity of ascertaining the state of the cloud. This
+       observation I have been able to make, and so to offer an
+       explanation of the phenomenon.</p>
+
+    <p>As the balloon sails on, borne forward by the wind, its
+    shadow travels either on the ground or on the clouds. This
+    shadow is, as a rule, black, like all others; but it frequently
+    happens that it appears alone on the surface of the ground, and
+    thus appears luminous. Examining this shadow by the aid of a
+    telescope, I have noticed that it is often composed of a dark
+    nucleus and a penumbra of the shape of an aureola. This
+    aureola, frequently very large in proportion to the diameter of
+    the central nucleus, eclipses it to the naked eye, so that the
+    whole shadow appears like a nebulous circle projected in yellow
+    upon the green ground of the woods and meadows. I have noticed,
+    too, that this luminous shadow is generally all the more
+    strongly marked in proportion to the greater humidity of the
+    surface of the ground.</p>
+
+    <p>Seen upon the clouds, this shadow sometimes presents a
+    curious aspect. I have often, when the balloon emerged from the
+    clouds into the clear sky, suddenly perceived, at twenty or
+    thirty yards' distance, a second balloon distinctly delineated,
+    and apparently of a grayish color, against the white ground of
+    the clouds. This phenomenon manifests itself at the moment when
+    the sun re-appears. The smallest details of the car can be made
+    out clearly, and our gestures are strikingly reproduced by the
+    shadow.</p><span class="pagenum"><a id="page276"></a>[pg 276]</span>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/276.png"><img width="600"
+             src="images/276.png"
+             alt=
+           "THE SHADOW OF THE BALLOON WAS SEEN BY US."></a><br>
+        THE SHADOW OF THE BALLOON WAS SEEN BY US.
+    </div>
+
+    <p>On April 15, 1868, at about half-past three in the
+    afternoon, we emerged from a stratum of clouds, when the shadow
+    of the balloon was seen by us, surrounded by colored concentric
+    circles, of which the car formed the centre. It was very
+    plainly visible upon a yellowish white ground. A first circle
+    of pale blue encompassed this ground and the car in a kind of
+    ring. Around this ring was a second of a deeper yellow, then a
+    grayish red zone, and lastly as the exterior circumference, a
+    fourth circle, violet in hue, and imperceptibly toning down
+    into the gray tint of the clouds. The slightest details were
+    clearly discernible&mdash;net, robes, and instruments. Every
+    one of our gestures was instantaneously reproduced by the
+    aerial spectres. The anthelion remained upon the clouds
+    sufficiently distinct, and for a sufficiently long time, to
+    permit of my taking a sketch in my journal and studying the
+    physical <span class="pagenum"><a id="page277"></a>[pg 277]</span> condition of the clouds
+       upon which it was produced. I was able to determine directly
+       the circumstances of its production. Indeed, as this
+       brilliant phenomenon occurred in the midst of the very
+       clouds which I was traversing, it was easy for me to
+       ascertain that these clouds were not formed of frozen
+       particles. The thermometer marked 2° above zero. The
+       hygrometer marked a maximum of humidity experienced, namely,
+       seventy-seven at three thousand seven hundred and seventy
+       feet, and the balloon was then at four thousand six hundred
+       feet, where the humidity was only seventy-three. It is
+       therefore certain that this is a phenomenon of the
+       diffraction of light simply produced by the vesicles of the
+       mist.</p>
+
+    <p>The name of diffraction is given to all the modifications
+    which the luminous rays undergo when they come in contact with
+    the surface of bodies. Light, under these circumstances, is
+    subject to a sort of deviation, at the same time becoming
+    decomposed, whence result those curious appearances in the
+    shadows of objects which were observed for the first time by
+    Grimaldi and Newton.</p>
+
+    <p>The most interesting phenomena of diffraction are those
+    presented by <i>gratings</i>, as are technically denominated
+    the systems of linear and very narrow openings situated
+    parallel to one another and at very small intervals. A system
+    of this kind may be realized by tracing with a diamond, for
+    instance, on a pane of glass equidistant lines very close
+    together. As the light would be able to pass in the interstices
+    between the strokes, whereas it would be stopped in the points
+    corresponding to those where the glass was not smooth,
+    <span class="pagenum"><a id="page278"></a>[pg 278]</span> there is, in reality, an
+       effect produced as if there were a series of openings very
+       near to each other. A hundred strokes, about 1/25th of an
+       inch in length, may thus be drawn without difficulty. The
+       light is then decomposed in spectra, each overlapping the
+       other. It is a phenomenon of this kind which is seen when we
+       look into the light with the eye half closed; the eyelashes
+       in this case, acting as a net-work or grating. These
+       net-works may also be produced by reflection, and it is to
+       this circumstance that are due the brilliant colors observed
+       when a pencil of luminous rays is reflected on a metallic
+       surface regularly striated.</p>
+
+    <p>To the phenomena of gratings must be attributed, too, the
+    colors, often so brilliant, to be seen in mother-of-pearl. This
+    substance is of a laminated structure; so much so, that in
+    carving it the different folds are often cut in such a way as
+    to form a regular net-work upon the surface. It is, again, to a
+    phenomenon of this sort that are due the rainbow hues seen in
+    the feathers of certain birds, and sometimes in spiders' webs.
+    The latter, although very fine, are not simple, for they are
+    composed of a large number of pieces joined together by a
+    viscous substance, and thus constitute a kind of net-work.</p>
+
+    <p>If the sun is near the horizon, and the shadow of the
+    observer falls upon the grass, upon a field of corn, or other
+    surface covered with dew, there is visible an aureola, the
+    light of which is especially bright about the head, but which
+    diminishes from below the middle of the body. This light is due
+    to the reflection of light by the moist stubble and the drops
+    of dew. It is brighter about the head, because the blades that
+    are <span class="pagenum"><a id="page279"></a>[pg 279]</span> near where the shadow of
+       the head falls expose to it all that part of them which is
+       lighted up, whereas those farther off expose not only the
+       part which is lighted up, but other parts which are not, and
+       this diminishes the brightness in proportion as their
+       distance from the <span class="pagenum"><a id="page280"></a>[pg 280]</span> head increases. The
+       phenomenon is seen whenever there is simultaneously mist and
+       sun. This fact is easily verified upon a mountain. As soon
+       as the shadow of a mountaineer is projected upon a mist, his
+       head gives rise to a shadow surrounded by a luminous
+       aureola.</p>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/279.jpg"><img width="400"
+             src="images/279.jpg"
+             alt="FOG-BOW SEEN FROM THE MATTERHORN."></a><br>
+        FOG-BOW SEEN FROM THE MATTERHORN.
+    </div>
+
+    <p><i>The Illustrated London News</i> of July 8, 1871,
+    illustrates one of these apparitions, "The Fog-Bow, seen from
+    the Matterhorn," observed by E. Whymper in this celebrated
+    region of the Alps. The observation was taken just after the
+    catastrophe of July 14, 1865; and by a curious coincidence, two
+    immense white aerial crosses projected into the interior of the
+    external arc. These two crosses were no doubt formed by the
+    intersection of circles, the remaining parts of which were
+    invisible. The apparition was of a grand and solemn character,
+    further increased by the silence of the fathomless abyss into
+    which the four ill-fated tourists had just been
+    precipitated.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/280.png"><img width="500"
+             src="images/280.png"
+             alt="Optical appearance"></a>
+    </div>
+
+    <p>Other optical appearances of an analogous kind are
+    manifested under different conditions. Thus, for instance, if
+    any one, turning his back to the sun, looks into water, he will
+    perceive the shadow of his head, but always very much deformed.
+    At the same time he will see starting from this very shadow
+    what seem to be <span class="pagenum"><a id="page281"></a>[pg 281]</span> luminous bodies, which dart
+       their rays in all directions with inconceivable rapidity,
+       and to a great distance. These luminous
+       appearances&mdash;these aureola rays&mdash;have, in addition
+       to the darting movement, a rapid rotary movement around the
+       head.</p>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/281.png"><img width="400"
+             src="images/281.png"
+             alt="decorative picture"></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="page282"></a>[pg 282]</span>
+
+    <h2>THE PLANET VENUS</h2>
+
+    <h3><span class="sc">By</span> AGNES M. CLERKE.</h3>
+    <hr class="short">
+
+    <h2>I.</h2>
+
+    <h3>HESPERUS AND PHOSPHOR.</h3>
+
+    <div class="figleft"
+         style="width:175px;">
+        <a href="images/282.png"><img width="175"
+             src="images/282.png"
+             alt="Torch carrier"></a>
+    </div>
+
+    <p>The radiant planet that hangs on the skirts of dusk and
+    dawn</p>
+
+    <blockquote>
+        <p>"like a jewel in an Ethiop's ear,"</p>
+    </blockquote>
+
+    <p>has been known and sung by poets in all ages. Its supremacy
+    over the remainder of the starry host is recognized in the name
+    given it by the Arabs, those nomad watchers of the skies, for
+    while they term the moon "El Azhar," "the Brighter One," and
+    the sun and moon together "El Azharan," "the Brighter Pair,"
+    they call Venus "Ez Zahra," the bright or shining one <i>par
+    excellence</i>, in which sense the same word is used to
+    describe a flower. This "Flower of Night" is supposed to be no
+    other than the white rose into which Adonis was changed by
+    Venus in the fable which is the basis of all early Asiatic
+    mythology. The morning and evening star is thus the celestial
+    symbol <span class="pagenum"><a id="page283"></a>[pg 283]</span> of that union between earth
+       and heaven in the vivifying processes of nature, typified in
+       the love of the goddess for a mortal.</p>
+
+    <p>The ancient Greeks, on the other hand, not unnaturally took
+    the star, which they saw alternately emerging from the
+    effulgence of the rising and setting sun, in the east and in
+    the west, for two distinct bodies, and named it differently
+    according to the time of its appearance. The evening star they
+    called Hesperus, and from its place on the western horizon,
+    fabled an earthly hero of that name, the son of Atlas, who from
+    the slopes of that mountain on the verge of the known world
+    used to observe the stars until eventually carried off by a
+    mighty wind, and so translated to the skies. These divine
+    honors were earned by his piety, wisdom, and justice as a ruler
+    of men, and his name long shed a shimmering glory over those
+    Hesperidean regions of the earth, where the real and unreal
+    touched hands in the mystical twilight of the unknown.</p>
+
+    <p>But the morning star shone with a different significance as
+    the herald of the day, the torchbearer who lights the way for
+    radiant Aurora on her triumphal progress through the skies.
+    Hence he was called Eosphorus, or Phosphorus, the bearer of the
+    dawn, translated into Latin as Lucifer, the Light-bearer. The
+    son of Eos, or Aurora, and the Titan Astraeus, he was of the
+    same parentage as the other multitude of the starry host, to
+    whom a similar origin was ascribed, and from whom in Greek
+    mythology he was evidently believed to differ only in the
+    superior order of his brightness. Homer, who mentions the
+    planet in the following passage:</p><span class=
+    "pagenum"><a id="page284"></a>[pg 284]</span>
+
+    <div class="poem">
+        <div class="stanza">
+            <p>"But when the star of Lucifer appeared,</p>
+
+            <p>The harbinger of light, whom following close,</p>
+
+            <p>Spreads o'er the sea the saffron-robed morn."</p>
+
+            <p class="i30">(<span class="sc">Lord Derby's</span>
+            "Iliad.")</p>
+        </div>
+    </div>
+
+    <p>recognizes no distinction between those celestial nomads,
+    the planets, "wandering stars," as the Arabs call them, which
+    visibly change their position relatively to the other stars,
+    and the latter, whose places on the sphere are apparently fixed
+    and immutable. In this he and his compatriots were far behind
+    the ancient Egyptians, who probably derived their knowledge
+    from still earlier speculators in Asia, for they not only
+    observed the movements of some at least of the planets, but
+    believed that Mercury and Venus revolved as satellites round
+    the sun, which in its turn circled round our lesser world.
+    Pythagoras is said to have been the first to identify Hesperus
+    with Phosphor, as the</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p class="i10">"Silver planet both of eve and
+            morn,"</p>
+        </div>
+    </div>
+
+    <p>and by Plato the same fact is recognized. The other planets,
+    all of which had, according to him, been originally named in
+    Egypt and Syria, have each its descriptive title in his
+    nomenclature. Thus the innermost, "the Star of Mercury," is
+    called Stilbon, "the Sparkler," Mars, Pyroeis, "the Fiery One,"
+    while Jupiter, the planet of the slowest course but one, is
+    designated as Phaeton, and Saturn, the tardiest of all,
+    Phaenon. These names were in later times abandoned in favor of
+    those of the divinities to whom they were respectively
+    dedicated, unalterably associated now with the days of the
+    week, over which they have been selected to
+    preside.</p><span class="pagenum"><a id="page285"></a>[pg 285]</span>
+
+    <p>The Copernican theory, which once and forever "brushed the
+    cobwebs out of the sky," by clearing away the mists of
+    pre-existing error, first completely explained the varying
+    positions of the Shepherd's star, irradiating the first or last
+    watch of night, according to her alternate function as the
+    follower or precursor of the sun. As she travels on a path
+    nearer to him by more than twenty-five and a half million miles
+    than that of the earth, she is seen by us on each side of him
+    in turn after passing behind or in front of him. The points at
+    which her orbit expands most widely to our eyes&mdash;an effect
+    of course entirely due to perspective, as her distance from the
+    sun is not then actually increased&mdash;are called her eastern
+    and western elongations; that at which she passes by the sun on
+    the hither side her inferior, and on the farther side her
+    superior conjunction. At both conjunctions she is lost to our
+    view, since she accompanies the sun so closely as to be lost in
+    his beams, rising and setting at the same time, and travelling
+    with him in his path through the heavens during the day. When
+    at inferior conjunction, or between us and the sun, she turns
+    her dark hemisphere to us like the new moon, and would
+    consequently be invisible in any case, but when in the opposite
+    position, shows us her illuminated face, and is literally a day
+    star, invisible only because effaced by the solar splendor. It
+    is as she gradually separates from him, after leaving this
+    latter position, circling over that half of her orbit which
+    lies to the east of him, that she begins to come into view as
+    an evening star, following him at a greater and greater
+    distance, and consequently setting later, until she attains her
+    greatest <span class="pagenum"><a id="page286"></a>[pg 286]</span> eastern elongation, divided
+       from the sun about 45° of his visible circuit through the
+       heavens, and consequently remaining above the horizon for
+       some four hours after him. From this point she again appears
+       to draw nearer to him until she passes on his hither side in
+       inferior conjunction, from which she emerges on the opposite
+       side to the westward, and begins to shine as a morning star,
+       preceding him on his track, at a gradually increasing
+       distance, until attaining her greatest westward elongation,
+       and finally completing her cycle by returning to superior
+       conjunction once more in a period of about five hundred and
+       eighty-four days.</p>
+
+    <p>Venus is thus Hesperus or Vesper, the evening star, when
+    following the sun as she passes from beyond him in superior
+    conjunction to inferior conjunction where she is nearest to the
+    earth. As she again leaves him behind in her course from this
+    point to the opposite one of superior conjunction, she appears
+    in her second aspect as Phosphorus or Lucifer, "the sun of
+    morning," and herald of the day, shining as</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p class="i22">"The fair star</p>
+
+            <p>That gems the glittering coronet of morn."</p>
+        </div>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <h2>II.</h2>
+
+    <h3>THE PHASES OF VENUS.</h3>
+
+    <p>But the changes in the aspect of Venus due to her varying
+    positions in her orbit are not confined to those which cause
+    her to oscillate with a pendulum movement eastward and westward
+    from the sun. The discovery that she undergoes phases exactly
+    like those of the moon, followed that of the existence of
+    Jupiter's <span class="pagenum"><a id="page287"></a>[pg 287]</span> satellites as the second
+       great result achieved by the use of the telescope in the
+       hands of Galileo. The fact that the planets were
+       intrinsically dark bodies revolving round the sun, and
+       reflecting its light, as he and Copernicus had maintained,
+       thus received a further ocular demonstration. The Florentine
+       astronomer describes in a letter to a friend how the planet,
+       after emerging from superior conjunction as a morning star,
+       gradually loses her rotundity on the side remote from the
+       luminary, changing first to a half sphere and then to a
+       waning crescent; until, after passing through the stage of
+       absolute extinction when intervening between us and the sun,
+       she re-appears as a morning star, and undergoes the same
+       series of transformations in inverse order. The revelation
+       was indeed so novel and unexpected, that when the slight
+       deformation of the planet's shape was first detected by him,
+       he did not venture to announce it in plain terms but veiled
+       it, according to the prevailing fashion of the time, under a
+       Latin anagram. His celebrated sentence&mdash;</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p>"Haec immatura a me jam frustra leguntur."</p>
+        </div>
+    </div>
+
+    <p>("Those incomplete observations are as yet read by me in
+    vain.")</p>
+
+    <p>forms, by transposing the letters, the more definite
+    statement,</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p>"Cynthiæ figuras æmulatur Mater Amorum."</p>
+        </div>
+    </div>
+
+    <p>("The mother of the loves imitates the aspects of Diana.")
+    <span class="pagenum"><a id="page288"></a>[pg 288]</span> that is to say, Venus vies
+       with the phases of the moon. The discovery was an important
+       one from its bearing on popular superstition ascribing to
+       the planets special influences on human affairs, for since
+       they were thus shown to transmit to us only borrowed light,
+       belief in their beneficent or malefic powers over man's
+       destinies received a rude shock.</p>
+
+    <div class="figright"
+         style="width:350px;">
+        <a href="images/287.png"><img width="350"
+             src="images/287.png"
+             alt="THE PHASES OF VENUS."></a><br>
+        THE PHASES OF VENUS.
+    </div>
+
+    <p>Galileo's announcement, published in September, 1610, when
+    only a slight flattening of the planet's disk was visible,
+    received absolute confirmation in the ensuing months, as she
+    completed her full half-circle of change on February 24th of
+    the following year, and consequently exhibited herself to him
+    in all her varying aspects. It was the first time they had been
+    looked upon by a human eye, since its unaided powers do not
+    enable it to discern them, although one exception to this rule
+    is said to have existed. This was the case of the Swiss
+    mathematician Gauss, who, when a child, on being shown the
+    crescent star through the telescope, exclaimed to his mother
+    that it "was turned wrong"; the inference being that he
+    recognized the reversal of the image in the field of the glass.
+    If it were indeed so, he deserves to rank with the Siberian
+    savage, who described the eclipses, or Jupiter's satellites; or
+    the shoemaker of Breslau, who could see and declare the
+    positions of those minute orbs.</p>
+
+    <p>The phases exhibited to us by Venus are due to her moving in
+    an orbit within that of the earth, at one side of which she is
+    between us and the sun, while at the other this position is
+    exactly reversed. We may compare her to a performer in a great
+    celestial circus, lit by a central chandelier, and ourselves to
+    spectators in an <span class="pagenum"><a id="page289"></a>[pg 289]</span> external ring, from which
+       we see her at one time facing us with the light full on her,
+       at the opposite point in complete shadow, and at the
+       intermediate ones in varying degrees of illumination
+       according to our changing views of her. The same
+       illustration may serve to show why Venus is brightest, not
+       when full, since she is then beyond the sun, and at the
+       farthest possible point from us, but when she approaches us
+       at inferior conjunction, more nearly by over one hundred and
+       thirty million miles, and still shows us a crescent of her
+       illuminated surface, before passing into the last phase of
+       total obscuration. When actually nearest to us she is
+       absolutely invisible, being then, like the new moon, between
+       us and the sun. Her varying degrees of brilliancy, even when
+       in the same phase, are thus accounted for by her alternate
+       retreat from and advance towards us as she circles round the
+       sun. Completing, as she does, her revolution in about seven
+       months and a half, she would of course go through the whole
+       series of her metamorphoses in that time, were the earth,
+       from which we observe them, a fixed point. Their protraction
+       instead, over a term of five hundred and eighty-four days,
+       or more than nineteen months, is due to the simultaneous
+       motion of the earth in the same direction, over her larger
+       orbit in a longer period, causing the same relative position
+       of the sister planet to recur only as often as she overtakes
+       her in her career. Thus the hour and minute hands of a
+       watch, moving at different rates of speed after meeting on
+       the dial plate at twelve o'clock, will not again come
+       together until five minutes past one, when the swifter paced
+       of the two will have completed a revolution and a twelfth.
+       But were we to <span class="pagenum"><a id="page290"></a>[pg 290]</span> retard the motion of the
+       latter, reducing it to only twice that of its companion,
+       they would always meet at the figure twelve, as it would
+       exactly complete two circuits while the hour hand was
+       performing one. Venus thus overtakes and passes the earth
+       once in five hundred and eighty-four days, or nearly two and
+       a half of her own years, constituting what is called her
+       synodic period of apparent revolution as seen from this
+       globe. She thus presents to us all the phases undergone by
+       our own satellite during a lunar month, passing from new to
+       full, and <i>vice versa</i>, through the various intervening
+       gradations of form.</p>
+
+    <p>The phases of Venus are amongst the most beautiful subjects
+    for observation in a moderate telescope, as her silver bow,
+    gradually brightening in the evening dusk, or fading in the
+    dawn,</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p>"On a bed of daffodil sky,"</p>
+        </div>
+    </div>
+
+    <p>is, after the two greater luminaries that rule the day and
+    night, the most brilliant object in the heavens.</p>
+
+    <p>&nbsp;</p>
+
+    <h2>III.</h2>
+
+    <h3>THE SILVER CROWN.</h3>
+
+    <p>The parallel between Venus and</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p>"That orbed maiden with fire laden,</p>
+
+            <p>Whom mortals call the moon,"</p>
+        </div>
+    </div>
+
+    <p>is carried a stage further. Most of us are familiar with the
+    spectacle in which the Ancient Egyptians saw symbolized Horus
+    on the lap of Isis, but which we more prosaically term "the old
+    moon in the new moon's <span class="pagenum"><a id="page291"></a>[pg 291]</span> arms." The strongly
+       illuminated half circle next the sun is then seen embracing
+       with its horns a dusky sphere, contrasting with it as
+       tarnished silver does with the newly burnished metal. The
+       same phenomenon is occasionally, though very rarely,
+       exhibited by Venus, while close to the sun at inferior
+       injunction, when the shadowy form of the full orb is seen to
+       shine dimly within her crescent with what is termed "the
+       ashen light." More wonderful still, this "glimmering sphere"
+       is then crowned, as with a silver halo, by a thin luminous
+       arch, forming a secondary sickle facing the one nearest the
+       sun, and doubtless due to the refraction of his rays round
+       the globe of the planet, through the upper regions of her
+       twilight atmosphere. This spectacle was first observed by
+       the Jesuit Ricciolo, an opponent of the Copernican theory,
+       on January 9th, 1643. He describes the planet as ruddy near
+       the sun, yellowish in the middle, and of greenish blue on
+       the side remote from the sun; while he also noted the bow of
+       light limiting the dark hemisphere. Scarcely daring to trust
+       his own eyesight, he ascribed these appearances, although he
+       recorded them, to illusory reflection in the telescope.</p>
+
+    <div class="figright"
+         style="width:300px;">
+        <a href="images/291.png"><img width="300"
+             src="images/291.png"
+             alt="VENUS AT HER GREATEST BRILLIANCY."></a><br>
+        VENUS AT HER GREATEST BRILLIANCY.
+    </div>
+
+    <p>They were again seen, however, by Derham about
+          <span class="pagenum"><a id="page292"></a>[pg 292]</span> 1715, and six years later
+       by Kirch, in Berlin, who has the following entry in his
+       diary for Saturday, June 29, 1721:&mdash;"I found Venus in a
+       region where the sky was not very clear. The planet was
+       narrow, and I seemed to see its dark side, though this is
+       almost incredible. The diameter of Venus was 65", and its
+       sickle seemed to tremble in the atmospheric vapors." Again,
+       on March 8th, 1726, he records a similar observation. "We
+       observed Venus with the twenty-six foot telescope. I
+       perceived her dark side, and its edge seemed to describe a
+       smaller circle than that of the light side, as is the case
+       of the moon." This effect is due to irradiation, that is to
+       say, to the glare from a bright surface, giving a deceptive
+       enlargement to its apparent area. He again saw the dark side
+       of the planet in October, 1759, as did Harding at Göttingen,
+       with Herschel's ten-foot reflector, on January 24th, 1806.
+       This latter observer saw it on this occasion stand out
+       against the background of the sky as of a pale ashen green,
+       while on February 28th following, it seemed to him of a pale
+       reddish gray, like the color of the eclipsed moon.</p>
+
+    <p>That the latter body should send to us from her nocturnal
+    shadows sufficient light to be visible is easily explicable,
+    since she is then flooded with earth-light reflected on her
+    from a surface thirteen and one-half times greater than her
+    own, and probably casting on her an illumination transcending
+    our full moonlight in the same proportion. But the secondary
+    light of Venus admits of no such explanation, since earth-light
+    on her surface, diminished by 1/12000th part compared to what
+    it is on that of the moon, would be quite insufficient to
+    <span class="pagenum"><a id="page293"></a>[pg 293]</span> render her visible to our
+       eyes. The phenomenon was therefore adduced as an argument
+       for the habitability of the planets by Gruithuisen, of the
+       Munich Observatory, who, writing early in this century,
+       suggested that the ashen light of Venus might be due to
+       general illuminations in celebration by her inhabitants of
+       some periodically recurring festivity, The materials for a
+       flare-up on so grand a scale would, he thought, exist in
+       abundance, as he conjectured the vegetation of our planetary
+       neighbor to be more luxuriant than that of our Brazilian
+       forests. The phosphorescence of the Aphroditean oceans, warm
+       and teeming with life, as they are held to be by Zollner,
+       was advanced as an explanatory hypothesis, with scarcely
+       more plausibility, by Professor Safarik, while others have
+       resorted to the supposition of atmospheric or electrical
+       luminosity producing on a large scale some such display as
+       that of the aurora borealis.</p>
+
+    <p>Professor Vogel, of Berlin, who himself saw part of the
+    night-side of Venus, in its semi-obscurity in November, 1871,
+    ascribed its visibility to a twilight effect caused by a very
+    extensive atmosphere. The light thus transmitted to us by
+    aerial diffusion and giving the ashen light, is reflected
+    sunlight, while that sent by the luminous arc on its edge is
+    direct sunlight, refracted, or bent round to us, from behind
+    the planet. The silver selvedge of the dawn edging the dark
+    limb may consequently be the brightest part of the broken
+    nimbus that then seems to surround her.</p>
+
+    <p>A similar appearance is observed during transits of Venus,
+    when she passes directly between us and the actual solar disk.
+    A silver thread is then seen encircling <span class=
+    "pagenum"><a id="page294"></a>[pg 294]</span> that side of the planet
+       which has not yet entered on the face of the sun or "a
+       shadowy nebulous ring," as it was described by Mr.
+       Macdonnell at Eden, surrounds the whole planetary disk when
+       two-thirds of it have passed the solar edge. As it moves off
+       it, the same aureole again becomes visible, testifying to
+       the existence of an atmosphere of considerable extent
+       exterior to the sharply outlined surface ordinarily visible.
+       The shimmering haze of reflected sunlight which perpetually
+       enfolds her is only made apparent to us under exceptional
+       circumstances which cut off some portion of her more
+       immediate light, just as we see the motes in the air
+       illuminated by a candle if we hide the actual flame from our
+       eyes. The perennial twilight which seems to reign over the
+       nocturnal hemisphere of Venus may compensate, perhaps, for
+       the want of a satellite to modify its darkness.</p>
+
+    <p>The great prolongation at other times of the horns of her
+    crescent, so as to embrace almost her entire circumference with
+    a tenuous ring of light, is doubtless due to the same cause, as
+    their visibility should otherwise be limited to a half segment
+    of a circle. The regions thus shining to us are obviously those
+    on which the sun has not yet set, his appearance above the
+    horizon being prolonged, as in our own case, by refraction,
+    though to a much larger extent. The magnitude of the sun's disk
+    as seen from Venus, a third larger than it appears to us, is
+    also adducted by Mr. Proctor in his posthumous work, "The Old
+    and the New Astronomy," edited and completed by Mr. A.C.
+    Ranyard, as an element in extending the illumination of Venus
+    to more than a hemisphere of her surface. As <span class=
+    "pagenum"><a id="page295"></a>[pg 295]</span> his diameter there is
+       44-1/4°, a zone of more than 22° wide outside the sunward
+       hemisphere is he thinks illuminated by direct though partial
+       sunlight, the orb being throughout this tract still
+       partially above the horizon.</p>
+
+    <div class="figcenter"
+         style="width:300px;">
+        <a href="images/295.png"><img width="300"
+             src="images/295.png"
+             alt="GEOGRAPHICAL ASPECT OF VENUS."></a><br>
+        GEOGRAPHICAL ASPECT OF VENUS.
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="page296"></a>[pg 296]</span>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/296-1.png"><img width="400"
+             src="images/296-1.png"
+             alt="Stars"></a>
+    </div>
+
+    <h2>THE STARS</h2>
+
+    <h4>(<span class="sc">From Starland.</span>)</h4>
+
+    <h3>BY SIR ROBERT S. BALL.</h3>
+    <hr class="short">
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/296-2.png"><img width="200"
+             src="images/296-2.png"
+             alt="Stars"></a>
+    </div>
+
+    <p>The group of bodies which cluster around our sun forms a
+    little island, so to speak, in the extent of infinite space. We
+    may illustrate this by a map in which we shall endeavor to show
+    the stars placed at their proper relative distances. We first
+    open the compasses one inch, and thus draw a little circle to
+    represent the path of the earth. We are not going to put in all
+    the planets. We take Neptune, the outermost, at once. To draw
+    its path I open the compasses to thirty inches, and draw a
+    circle with that radius. That will do for our solar system,
+    though the comets no doubt will roam beyond these limits. To
+    complete our map we ought of course to put in some stars. There
+    are a hundred million to choose from, and we shall begin with
+    the brightest. It is often called the Dog Star, but astronomers
+    know it better as Sirius. Let us see where it is to be placed
+    on our <span class="pagenum"><a id="page297"></a>[pg 297]</span> map. Sirius is beyond
+       Neptune, so it must be outside somewhere. Indeed, it is a
+       good deal further off than Neptune; so I try at the edge of
+       the drawing-board; I have got a method of making a little
+       calculation that I do not intend to trouble you with, but I
+       can assure you that the results it leads me to are quite
+       correct; they show me that this board is not big enough. But
+       could a board which was big enough fit into this lecture
+       theatre? Here, again, I make my little calculations, and I
+       find that there would not be room for a board sufficiently
+       great; in fact, if I put the sun here at one end, with its
+       planets around it? Sirius would be too near on the same
+       scale if it were at the further corner. The board would have
+       to go out through the wall of the theatre, out through
+       London. Indeed, big as London is, it would not be large
+       enough to contain the drawing-board that I should require.
+       It would have to stretch about twenty miles from where we
+       are now assembled. We may therefore dismiss any hope of
+       making a practical map of our system on this scale if Sirius
+       is to have its proper place. Let us, then, take some other
+       star. We shall naturally try with the nearest of all. It is
+       one that we do not know in this part of the world, but those
+       that live in the southern hemisphere are well acquainted
+       with it. The name of this star is Alpha Centauri. Even for
+       this star we should require a drawing three or four miles
+       long if the distance from the earth to the sun is to be
+       taken as one inch. You see what an isolated position our sun
+       and his planets occupy. The members of the family are all
+       close together, and the nearest neighbors are situated at
+       enormous distances. There is a good reason <span class=
+       "pagenum"><a id="page298"></a>[pg 298]</span> for this separation. The
+       stars are very pretty and perfectly harmless to us where
+       they are at present situated. They might be very troublesome
+       neighbors if they were very much closer to our system. It is
+       therefore well they are so far off; they would be constantly
+       making disturbances in the sun's family if they were near at
+       hand. Sometimes they would be dragging us into unpleasantly
+       great heat by bringing us too close to the sun, or producing
+       a coolness by pulling us away from the sun, which would be
+       quite as disagreeable.</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>The Stars are Suns.</b></p>
+
+    <p>We are about to discuss one of the grandest truths in the
+    whole of nature. We have had occasion to see that this sun of
+    ours is a magnificent globe immensely larger than the greatest
+    of his planets, while the greatest of these planets is
+    immensely larger than this earth; but now we are to learn that
+    our sun is, indeed, only a star not nearly so bright as many of
+    those which shine over our heads every night. We are
+    comparatively close to the sun, so that we are able to enjoy
+    his beautiful light and cheering heat. Each of those other
+    myriads of stars is a sun, and the splendor of those distant
+    suns is often far greater than that of our own. We are,
+    however, so enormously far from them that they appear dwindled
+    down to insignificance. To judge impartially between our sun or
+    star and such a sun or star as Sirius we should stand halfway
+    between the two; it is impossible to make a fair estimate when
+    we find ourselves situated close to one star and a million
+    times as far from the other. After allowance is made for the
+    imperfections of our point of view, we are <span class=
+    "pagenum"><a id="page299"></a>[pg 299]</span> enabled to realize the
+       majestic truth that the sun is no more than a star, and that
+       the other stars are no less than suns. This gives us an
+       imposing idea of the extent and magnificence of the universe
+       in which we are situated. Look lip at the sky at
+       night&mdash;you will see a host of stars; try to think that
+       every one of them is itself a sun. It may probably be that
+       those suns have planets circling round them, but it is
+       hopeless for us to expect to see such planets. Were you
+       standing on one of those stars and looking towards our
+       system, you would not perceive the sun to be the brilliant
+       and gorgeous object that we know so well. If you could see
+       him at all, he would merely seem like a star, not nearly as
+       bright as many of those you can see at night. Even if you
+       had the biggest of telescopes to aid your vision, you could
+       never discern from one of these bodies the planets which
+       surround the sun, no astronomer in the stars could see
+       Jupiter, even if his sight were a thousand times as powerful
+       as any sight or telescope that we know. So minute an object
+       as our earth would, of course, be still more hopelessly
+       beyond the possibility of vision.</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>The Number of the Stars.</b></p>
+
+    <p>To count the stars involves a task which lies beyond the
+    power of man to accomplish. Even without the aid of any
+    telescope, we can see a great multitude of stars from this part
+    of the world. There are also many constellations in the
+    southern hemisphere which never appear above our horizon. If,
+    however, we were to go to the equator, then, by waiting there
+    for a twelve-month, all the stars in the heavens would have
+    been <span class="pagenum"><a id="page300"></a>[pg 300]</span> successively exposed to
+       view. An astronomer, Houzeau, with the patience to count
+       them, enumerated about six thousand. This is the naked-eye
+       estimate of the star-population of the heavens; but if
+       instead of relying on unaided vision, you get the assistance
+       of a little telescope, you will be astounded at the enormous
+       multitude of stars which are disclosed.</p>
+
+    <div class="figleft"
+         style="width:400px;">
+        <a href="images/300.jpg"><img width="400"
+             src="images/300.jpg"
+             alt="FIG 1. THE GREAT BEAR AND THE POLE."></a><br>
+        FIG 1. THE GREAT BEAR AND THE POLE.
+    </div>
+
+    <p>An ordinary opera-glass or binocular is a very useful
+    instrument for looking at the stars in the heavens. If you
+    employ an instrument of this sort, you will be amazed to find
+    that the heavens teem with additional hosts of stars that your
+    unaided vision would never have given you knowledge of. Any
+    part of the sky may be observed; but, just to give an
+    illustration, I shall take one special region, namely, that of
+    the Great Bear (Fig. 1). The seven well-known stars are here
+    shown, four of which form a sort of oblong, while the other
+    three represent the tail. I would like you to make this little
+    experiment. On a fine clear night, count how many stars there
+    are within this oblong; they are all very faint, but you will
+    be able to see a few, and, with good sight, and on a clear
+    night, you may see perhaps ten. Next take your opera-glass and
+    sweep it over the same region; if you will carefully count the
+    stars <span class="pagenum"><a id="page301"></a>[pg 301]</span> it shows, you will find
+       fully two hundred; so that the opera-glass has, in this part
+       of the sky, revealed nearly twenty times as many stars as
+       could be seen without its aid. As six thousand stars can be
+       seen by the eye all over the heavens, we may fairly expect
+       that twenty times that number&mdash;that is to say, one
+       hundred and twenty thousand stars&mdash;could be shown by
+       the opera-glass over the entire sky. Let us go a step
+       further, and employ a telescope, the object-glass of which
+       is three inches across. This is a useful telescope to have,
+       and, if a good one, will show multitudes of pleasing
+       objects, though an astronomer would not consider it very
+       powerful. An instrument like this, small enough to be
+       carried in the hand, has been applied to the task of
+       enumerating the stars in the northern half of the sky, and
+       three hundred and twenty thousand stars were counted.
+       Indeed, the actual number that might have been seen with it
+       is considerably greater, for when the astronomer Argelander
+       made this memorable investigation he was unable to reckon
+       many of the stars in localities where they lay very close
+       together. This grand count only extended to half the sky,
+       and, assuming that the other half is as richly inlaid with
+       stars, we see that a little telescope like that we have
+       supposed will, when swept over the heavens, reveal a number
+       of stars which exceeds that of the population of any city in
+       England except London. It exhibits more than one hundred
+       times as many stars as our eyes could possibly reveal.
+       Still, we are only at the beginning of the count; the very
+       great telescopes add largely to the number. There are
+       multitudes of stars which in small instruments
+          <span class="pagenum"><a id="page302"></a>[pg 302]</span> we cannot see, but which
+       are distinctly visible from our great observatories. That
+       telescope would be still but a comparatively small one which
+       would show as many stars in the sky as there are people
+       living in the mighty city of London; and with the greatest
+       instruments, the tale of stars has risen to a number far
+       greater than that of the entire population of Great
+       Britain.</p>
+
+    <p>In addition to those stars which the largest telescopes show
+    us, there are myriads which make their presence evident in a
+    wholly different way. It is only in quite recent times that an
+    attempt has been made to develop fully the powers of
+    photography in representing the celestial objects. On a
+    photographic plate which has been exposed to the sky in a great
+    telescope the stars are recorded by thousands. Many of these
+    may, of course, be observed with a good telescope, but there
+    are not a few others which no one ever saw in a telescope,
+    which apparently no one ever could see, though the photograph
+    is able to show them. We do not, however, employ a camera like
+    that which the photographer uses who is going to take your
+    portrait. The astronomer's plate is put into his telescope, and
+    then the telescope is turned towards the sky. On that plate the
+    stars produce their images, each by its own light. Some of
+    these images are excessively faint, but we give a very long
+    exposure of an hour or two hours; sometimes as much as four
+    hours' exposure is given to a plate so sensitive that a mere
+    fraction of a second would sufficiently expose it during the
+    ordinary practice of taking a photograph in daylight. We thus
+    afford sufficient time to enable the fainter objects to
+    indicate their presence <span class="pagenum"><a id="page303"></a>[pg 303]</span> upon the sensitive film.
+       Even with an exposure of a single hour a picture exhibiting
+       sixteen thousand stars has been taken by Mr. Isaac Roberts,
+       of Liverpool. Yet the portion of the sky which it represents
+       is only one ten-thousandth part of the entire heavens. It
+       should be added that the region which Mr. Roberts has
+       photographed is furnished with stars in rather exceptional
+       profusion.</p>
+
+    <p>Here, at last, we have obtained some conception of the
+    sublime scale on which the stellar universe is constructed. Yet
+    even these plates cannot represent all the stars that the
+    heavens contain. We have every reason for knowing that with
+    larger telescopes, with more sensitive plates, with more
+    prolonged exposures, ever fresh myriads of stars will be
+    brought within our view.</p>
+
+    <p>You must remember that every one of these stars is truly a
+    sun, a lamp, as it were, which doubtless gives light to other
+    objects in its neighborhood as our sun sheds light upon this
+    earth and the other planets. In fact, to realize the glories of
+    the heavens you should try to think that the brilliant points
+    you see are merely the luminous points of the otherwise
+    invisible universe.</p>
+
+    <p>Standing one fine night on the deck of a Cunarder we passed
+    in open ocean another great Atlantic steamer. The vessel was
+    near enough for us to see not only the light from the mast-head
+    but also the little beams from the several cabin ports; and we
+    could see nothing of the ship herself. Her very existence was
+    only known to us by the twinkle of these lights. Doubtless her
+    passengers could see, and did see, the similar lights from our
+    own vessel, and they probably drew the correct inference that
+    these lights indicated a great ship. <span class=
+    "pagenum"><a id="page304"></a>[pg 304]</span> Consider the multiplicity
+       of beings and objects in a ship: the captain and the crew,
+       the passengers, the cabins, the engines, the boats, the
+       rigging, and the stores. Think of all the varied interests
+       there collected and then reflect that out on the ocean, at
+       night, the sole indication of the existence of this
+       elaborate structure was given by the few beams of light that
+       happened to radiate from it. Now raise your eyes to the
+       stars; there are the twinkling lights. We cannot see what
+       those lights illuminate, we can only conjecture what untold
+       wealth of non-luminous bodies may also lie in their
+       vicinity; we may, however, feel certain that just as the few
+       gleaming lights from a ship are utterly inadequate to give a
+       notion of the nature and the contents of an Atlantic
+       steamer, so are the twinkling stars utterly inadequate to
+       give even the faintest conception of the extent and the
+       interest of the universe. We merely see self-luminous
+       bodies, but of the multitudes of objects and the elaborate
+       systems of which these bodies are only the conspicuous
+       points we see nothing and we know very little. We are,
+       however, entitled to infer from an examination of our own
+       star&mdash;the sun&mdash;and of the beautiful system by
+       which it is surrounded, that these other suns may be also
+       splendidly attended. This is quite as reasonable a
+       supposition as that a set of lights seen at night on the
+       Atlantic Ocean indicates the existence of a fine ship.</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>The Clusters of Stars.</b></p>
+
+    <p>On a clear night you can often see, stretching across the
+    sky, a track of faint light, which is known to astronomers as
+    the "Milky Way." It extends below the <span class=
+    "pagenum"><a id="page305"></a>[pg 305]</span> horizon, and then round the
+       earth to form a girdle about the heavens. When we examine
+       the Milky Way with a telescope we find, to our amazement,
+       that it consists of myriads of stars, so small and so faint
+       that we are not able to distinguish them individually; we
+       merely see the glow produced from their collective rays.
+       Remembering that our sun is a star, and that the Milky Way
+       surrounds us, it would almost seem as if our sun were but
+       one of the host of stars which form this cluster.</p>
+
+    <p>There are also other clusters of stars, some of which are
+    exquisitely beautiful telescopic spectacles. I may mention a
+    celebrated pair of these objects which lies in the
+    constellation of Perseus. The sight of them in a great
+    telescope is so imposing that no one who is fit to look through
+    a telescope could resist a shout of wonder and admiration when
+    first they burst on his view. But there are other clusters.
+    Here is a picture of one which is known as the "Globular
+    Cluster in the Centaur" (Fig. 2). It consists of a ball of
+    stars, so far off that, however large these several suns may
+    actually be, they have dwindled down to extremely small points
+    of light. A homely illustration may serve to show the
+    appearance which a globular cluster presents in a good
+    telescope. I take a pepper-caster, and on a sheet of
+    <span class="pagenum"><a id="page306"></a>[pg 306]</span> white paper I begin to
+       shake out the pepper until there is a little heap at the
+       centre and other grains are scattered loosely about. Imagine
+       that every one of those grains of pepper was to be
+       transformed into a tiny electric light, and then you have
+       some idea of what a cluster of stars would look like when
+       viewed through a telescope of sufficient power. There are
+       multitudes of such groups scattered through the depths of
+       space. They require our biggest telescopes to show them
+       adequately. We have seen that our sun is a star, being only
+       one of a magnificent cluster that forms the Milky Way. We
+       have also seen that there are other groups scattered through
+       the length and depth of space. It is thus we obtain a notion
+       of the rank which our earth holds in the scheme of things
+       celestial.</p>
+
+    <div class="figright"
+         style="width:300px;">
+        <a href="images/305.png"><img width="300"
+             src="images/305.png"
+             alt=
+           "FIG. 2. GLOBULAR CLUSTER IN THE CENTAUR."></a><br>
+        FIG. 2. GLOBULAR CLUSTER IN THE CENTAUR.
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p><b>The Rank of the Earth as a Globe in Space.</b></p>
+
+    <p>Let me give an illustration with the view of explaining more
+    fully the nature of the relation which the earth bears to the
+    other globes which abound through space, and you must allow me
+    to draw a little upon my imagination. I shall suppose that the
+    mails of our country extend not only over this globe, but that
+    they also communicate with other worlds; that postal
+    arrangements exist between Mars and the earth, between the sun
+    and Orion&mdash;in fact, everywhere throughout the whole extent
+    of the universe. We shall consider how our letters are to be
+    addressed. Let us take the case of Mr. John Smith, merchant,
+    who lives at 1001, Piccadilly; and let us suppose that Mr. John
+    Smith's business transactions are of such an extensive nature
+    that they reach not only all over this globe, but away
+    throughout space. <span class="pagenum"><a id="page307"></a>[pg 307]</span> I shall suppose that the
+       firm has a correspondent residing&mdash;let us say in the
+       constellation of the Great Bear; and when this man of
+       business wants to write to Mr. Smith from these remote
+       regions, what address must he put upon the letter, so that
+       the Postmaster-General of the universe shall make no mistake
+       about its delivery? He will write as follows:&mdash;</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p>MR. JOHN SMITH,</p>
+
+            <p class="i4">1001 Piccadilly,</p>
+
+            <p class="i8">London,</p>
+
+            <p class="i12">England,</p>
+
+            <p class="i16">Europe,</p>
+
+            <p class="i20">Earth,</p>
+
+            <p class="i24">Near the Sun,</p>
+
+            <p class="i28">Milky Way,</p>
+
+            <p class="i32">The Universe.</p>
+        </div>
+    </div>
+
+    <p>Let us now see what the several lines of this address mean.
+    Of course we put down the name of Mr. John Smith in the first
+    line, and then we will add "1001 Piccadilly" for the second;
+    but as the people in the Great Bear are not likely to know
+    where Piccadilly is, we shall add "London" underneath. As even
+    London itself cannot be well known everywhere, it is better to
+    write "England." This would surely find Mr. John Smith from any
+    post-office on this globe. From other globes, however, the
+    supreme importance of England may not be so immediately
+    recognized, and therefore it is as well to add another line,
+    "Europe." This ought to be sufficient, I think, for any
+    post-office in the solar system. Europe is big enough to be
+    visible from Mars or Venus, and should be known to the
+    post-office people there, just as we know and have names for
+    the continents on Mars. But further away there might be a
+    <span class="pagenum"><a id="page308"></a>[pg 308]</span> little difficulty; from
+       Uranus and Neptune the different regions on our earth can
+       never have been distinguished, and therefore we must add
+       another line to indicate the particular globe of the solar
+       system which contains Europe. Mark Twain tells us that there
+       was always one thing in astronomy which specially puzzled
+       him, and that was to know how we found out the names of the
+       stars. We are, of course, in hopeless ignorance of the name
+       by which this earth is called among other intelligent beings
+       elsewhere who can see it. I can only adopt the title of
+       "Earth," and therefore I add this line. Now our address is
+       so complete that from anywhere in the solar
+       system&mdash;from Mercury, from Jupiter, or
+       Neptune&mdash;there ought to be no mistake about the letter
+       finding its way to Mr. John Smith. But from his
+       correspondent in the Great Bear this address would be still
+       incomplete; they cannot see our earth from there, and even
+       the sun himself only looks like a small star&mdash;like one,
+       in fact, of thousands of stars elsewhere. However, each star
+       can be distinguished, and our sun may, for instance, be
+       recognized from the Great Bear by some designation. We shall
+       add the line "Near the Sun," and then I think that from this
+       constellation, or from any of the other stars around us, the
+       address of Mr. John Smith may be regarded as complete. But
+       Mr. Smith's correspondence may be still wider. He may have
+       an agent living in the cluster of Perseus or on some other
+       objects still fainter and more distant; then "Near the Sun"
+       is utterly inadequate as a concluding line to the address,
+       for the sun, if it can be seen at all from thence, will be
+       only of the significance of an excessively minute star, no
+       more to be <span class="pagenum"><a id="page309"></a>[pg 309]</span> designated by a special
+       name than are each of the several leaves on the trees of a
+       forest. What this distant correspondent will be acquainted
+       with is not the earth or the sun but only the cluster of
+       stars among which the sun is but a unit. Again we use our
+       own name to denote the cluster, and we call it the "Milky
+       Way." When we add this line, we have made the address of Mr.
+       John Smith as complete as circumstances will permit. I think
+       a letter posted to him anywhere ought to reach its
+       destination. To perfect it, however, we will finish up with
+       one line more&mdash;"The Universe."</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>The Distances of the Stars.</b></p>
+
+    <p>I must now tell you something about the distances of the
+    stars. I shall not make the attempt to explain fully how
+    astronomers make such measurements, but I will give you some
+    notion of how it is done. You may remember I showed you how we
+    found the distance of a globe that was hung from the ceiling.
+    The principle of the method for finding the distance of a star
+    is somewhat similar, except that we make the two observations
+    not from the two ends of a table, not even from opposite sides
+    of the earth, but from two opposite points on the earth's
+    orbit, which are therefore at a distance of one hundred and
+    eighty-six million miles. Imagine that on Midsummer Day, when
+    standing on the earth here, I measure with a piece of card the
+    angle between the star and the sun. Six months later, on
+    Midwinter Day, when the earth is at the opposite point of its
+    orbit, I again measure the angle between the same star and the
+    sun, and we can now determine the star's distance by making a
+    triangle. I draw a line a foot <span class=
+       "pagenum"><a id="page310"></a>[pg 310]</span> long, and we will take this
+       foot to represent one hundred and eighty-six million miles,
+       the distance between the two stations; then placing the
+       cards at the corners, I rule the two sides and complete the
+       triangle, and the star must be at the remaining corner; then
+       I measure the sides of the triangle, and how many feet they
+       contain, and recollecting that each foot corresponds to one
+       hundred and eighty-six million miles, we discover the
+       distance of the star. If the stars were comparatively near
+       us, the process would be a very simple one; but,
+       unfortunately, the stars are so extremely far off that this
+       triangle, even with a base of only one foot, must have its
+       sides many miles long. Indeed, astronomers will tell you
+       that there is no more delicate or troublesome work in the
+       whole of their science than that of discovering the distance
+       of a star.</p>
+
+    <p>In all such measurements we take the distance from the earth
+    to the sun as a conveniently long measuring-rod, whereby to
+    express the results. The nearest stars are still hundreds of
+    thousands of times as far off as the sun. Let us ponder for a
+    little on the vastness of these distances. We shall first
+    express them in miles. Taking the sun's distance to be
+    ninety-three million miles, then the distance of the nearest
+    fixed star is about twenty millions of millions of
+    miles&mdash;that is to say, we express this by putting down a 2
+    first, and then writing thirteen ciphers after it. It is, no
+    doubt, easy to speak of such figures, but it is a very
+    different matter when we endeavor to imagine the awful
+    magnitude which such a number indicates. I must try to give
+    some illustrations which will enable you to form a notion of
+    it. At first I was going to ask you to try and
+          <span class="pagenum"><a id="page311"></a>[pg 311]</span> count this number, but when
+       I found it would require at least three hundred thousand
+       years, counting day and night without stopping, before the
+       task was over, it became necessary to adopt some other
+       method.</p>
+
+    <p>When on a visit in Lancashire I was once kindly permitted to
+    visit a cotton mill, and I learned that the cotton yarn there
+    produced in a single day would be long enough to wind round
+    this earth twenty-seven times at the equator. It appears that
+    the total production of cotton yarn each day in all the mills
+    together would be on the average about one hundred and
+    fifty-five million miles. In fact, if they would only spin
+    about one-fifth more, we could assert that Great Britain
+    produced enough cotton yarn every day to stretch from the earth
+    to the sun and back again! It is not hard to find from these
+    figures how long it would take for all the mills in Lancashire
+    to produce a piece of yarn long enough to reach from our earth
+    to the nearest of the stars. If the spinners worked as hard as
+    ever they could for a year, and if all the pieces were then
+    tied together, they would extend to only a small fraction of
+    the distance; nor if they worked for ten years, or for twenty
+    years, would the task be fully accomplished. Indeed, upwards of
+    four hundred years would be necessary before enough cotton
+    could be grown in America and spun in this country to stretch
+    over a distance so enormous. All the spinning that has ever yet
+    been done in the world has not formed a long enough thread!</p>
+
+    <p>There is another way in which we can form some notion of the
+    immensity of these sidereal distances. You will recollect that,
+    when we were speaking of Jupiter's moons, I told you of the
+    beautiful discovery <span class="pagenum"><a id="page312"></a>[pg 312]</span> which their eclipses
+       enabled astronomers to make. It was thus found that light
+       travels at the enormous speed of about one hundred and
+       eighty-five thousand miles per second. It moves so quickly
+       that within a single second a ray would flash two hundred
+       times from London to Edinburgh and back again.</p>
+
+    <p>We said that a meteor travels one hundred times as swiftly
+    as a rifle-bullet; but even this great speed seems almost
+    nothing when compared with the speed of light, which is ten
+    thousand times as great. Suppose some brilliant outbreak of
+    light were to take place in a distant star&mdash;an outbreak
+    which would be of such intensity that the flash from it would
+    extend far and wide throughout the universe. The light would
+    start forth on its voyage with terrific speed. Any neighboring
+    star which was at a distance of less than one hundred and
+    eighty-five thousand miles would, of course, see the flash
+    within a second after it had been produced. More distant bodies
+    would receive the intimation after intervals of time
+    proportioned to their distances. Thus, if a body were one
+    million miles away, the light would reach it in from five to
+    six seconds, while over a distance as great as that which
+    separates the earth from the sun the news would be carried in
+    about eight minutes. We can calculate how long a time must
+    elapse ere the light shall travel over a distance so great as
+    that between the star and our earth. You will find that from
+    the nearest of the stars the time required for the journey will
+    be over three years. Ponder on all that this involves. That
+    outbreak in the star might be great enough to be visible here,
+    but we could never become aware of it till three years after
+    <span class="pagenum"><a id="page313"></a>[pg 313]</span> it had happened. When we
+       are looking at such a star to-night we do not see it as it
+       is at present, for the light that is at this moment entering
+       our eyes has travelled so far that it has been three years
+       on the way. Therefore, when we look at the star now we see
+       it as it was three years previously. In fact, if the star
+       were to go out altogether, we might still continue to see it
+       twinkling for a period of three years longer, because a
+       certain amount of light was on its way to us at the moment
+       of extinction, and so long as that light keeps arriving
+       here, so long shall we see the star showing as brightly as
+       ever. When, therefore, you look at the thousands of stars in
+       the sky to-night, there is not one that you see as it is
+       now, but as it was years ago.</p>
+
+    <p>I have been speaking of the stars that are nearest to us,
+    but there are others much farther off. It is true we cannot
+    find the distances of these more remote objects with any degree
+    of accuracy, but we can convince ourselves how great that
+    distance is by the following reasoning. Look at one of the
+    brightest stars. Try to conceive that the object was carried
+    away further into the depths of space, until it was ten times
+    as far from us as it is at present, it would still remain
+    bright enough to be recognized in quite a small telescope; even
+    if it were taken to one hundred times its original distance it
+    would not have withdrawn from the view of a good telescope;
+    while if it retreated one thousand times as far as it was at
+    first it would still be a recognizable point in our mightiest
+    instruments. Among the stars which we can see with our
+    telescopes, we feel confident there must be many from which the
+    light has expended hundreds of years, or even thousands of
+    years, <span class="pagenum"><a id="page314"></a>[pg 314]</span> on the journey. When,
+       therefore, we look at such objects, we see them, not as they
+       are now, but as they were ages ago; in fact, a star might
+       have ceased to exist for thousands of years, and still be
+       seen by us every night as a twinkling point in our great
+       telescopes.</p>
+
+    <p>Remembering these facts, you will, I think, look at the
+    heavens with a new interest. There is a bright star, Vega, or
+    Alpha Lyræ, a beautiful gem, so far off that the light from it
+    which now reaches our eyes started before many of my audience
+    were born. Suppose that there are astronomers residing on
+    worlds amid the stars, and that they have sufficiently powerful
+    telescopes to view this globe, what do you think they would
+    observe? They will not see our earth as it is at present; they
+    will see it as it was years (and sometimes many years) ago.
+    There are stars from which if England could now be seen, the
+    whole of the country would be observed at this present moment
+    to be in a great state of excitement at a very auspicious
+    event. Distant astronomers might notice a great procession in
+    London, and they could watch the coronation of a youthful queen
+    amid the enthusiasm of a nation. There are other stars still
+    further, from which, if the inhabitants had good enough
+    telescopes, they would now see a mighty battle in progress not
+    far from Brussels. One splendid army could be beheld hurling
+    itself time after time against the immovable ranks of the
+    other. They would not, indeed, be able to hear the
+    ever-memorable "Up, Guards, and at them!" but there can be no
+    doubt that there are stars so far away that the rays of light
+    which started from the earth on the day of the battle of
+    Waterloo are only just arriving there. Further off
+          <span class="pagenum"><a id="page315"></a>[pg 315]</span> still, there are stars from
+       which a bird's-eye view could be taken at this very moment
+       of the signing of Magna Charta. There are even stars from
+       which England, if it could be seen at all, would now appear,
+       not as the great England we know, but as a country covered
+       by dense forests, and inhabited by painted savages, who
+       waged incessant war with wild beasts that roamed through the
+       island. The geological problems that now puzzle us would be
+       quickly solved could we only go far enough into space and
+       had we only powerful enough telescopes. We should then be
+       able to view our earth through the successive epochs of past
+       geological time; we should be actually able to see those
+       great animals whose fossil remains are treasured in our
+       museums tramping about over the earth's surface, splashing
+       across its swamps, or swimming with broad flippers through
+       its oceans. Indeed, if we could view our own earth reflected
+       from mirrors in the stars, we might still see Moses crossing
+       the Red Sea, or Adam and Eve being expelled from Eden.</p>
+
+    <p>So important is the subject of star distance that I am
+    tempted to give one more illustration in order to bring before
+    you some conception of how vast such distances are. I shall
+    take, as before, the nearest of the stars so far as known to
+    us, and I hope to be forgiven for taking an illustration of a
+    practical and a commercial kind instead of one more purely
+    scientific. I shall suppose that a railway is about to be made
+    from London to Alpha Centauri. The length of that railway, of
+    course, we have already stated: it is twenty billions of miles.
+    So I am now going to ask your attention to the simple question
+    as to the fare which it would be reasonable to
+          <span class="pagenum"><a id="page316"></a>[pg 316]</span> charge for the journey. We
+       shall choose a very cheap scale on which to compute the
+       price of a ticket. The parliamentary rate here is, I
+       believe, a penny for every mile. We will make our
+       interstellar railway fares much less even than this; we
+       shall arrange to travel at the rate of one hundred miles for
+       every penny. That, surely, is moderate enough. If the
+       charges were so low that the journey from London to
+       Edinburgh only cost fourpence, then even the most
+       unreasonable passenger would be surely contented. On these
+       terms how much do you think the fare from London to this
+       star ought to be? I know of one way in which to make our
+       answer intelligible. There is a National Debt with which
+       your fathers are, unhappily, only too well acquainted; you
+       will know quite enough about it yourselves in those days
+       when you have to pay income tax. This debt is so vast that
+       the interest upon it is about sixty thousand pounds a day,
+       the whole amount of the National Debt being six hundred and
+       thirty-eight millions of pounds.</p>
+
+    <p>If you went to the booking-office with the whole of this
+    mighty sum in your pocket&mdash;but stop a moment; could you
+    carry it in your pocket? Certainly not, if it were in
+    sovereigns. You would find that after you had as many
+    sovereigns as you could conveniently carry there would still be
+    some left&mdash;so many, indeed, that it would be necessary to
+    get a cart to help you on with the rest. When the cart had as
+    great a load of sovereigns as the horse could draw there would
+    be still some more, and you would have to get another cart; but
+    ten carts, twenty carts, fifty carts, would not be enough. You
+    would want five thousand of these before you <span class=
+    "pagenum"><a id="page317"></a>[pg 317]</span> would be able to move off
+       towards the station with your money. When you did get there
+       and asked for a ticket at the rate of one hundred miles for
+       a penny, do you think you would get any change? No doubt
+       some little time would be required to count the money, but
+       when it was counted the clerk would tell you that there was
+       not enough&mdash;that he must have nearly two hundred
+       millions of pounds more.</p>
+
+    <p>That will give some notion of the distance of the nearest
+    star, and we may multiply it by ten, by one hundred, and even
+    by one thousand, and still not attain to the distance of some
+    of the more remote stars that the telescope shows us.</p>
+
+    <p>On account of the immense distances of the stars we can only
+    perceive them to be mere points of light. We can never see a
+    star to be a globe with marks on it like the moon, or like one
+    of the planets&mdash;in fact, the better the telescope the
+    smaller does the star seem, though, of course, its brightness
+    is increased with every addition to the light-grasping power of
+    the instrument.</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>The Brightness and Color of Stars.</b></p>
+
+    <p>Another point to be noticed is the arrangement of stars in
+    classes, according to their lustre. The brightest stars, of
+    which there are about twenty, are said to be of the first
+    magnitude. Those just inferior to the first magnitude are
+    ranked as the second; and those just lower than the second are
+    estimated as the third; and so on. The smallest points that
+    your unaided eyes will show you are of about the sixth
+    magnitude. Then the telescope will reveal stars still fainter
+    and fainter, down to what we term the seventeenth or eighteenth
+    <span class="pagenum"><a id="page318"></a>[pg 318]</span> magnitudes, or even lower
+       still. The number of stars of each magnitude increases very
+       much in the classes of small ones.</p>
+
+    <div class="figright"
+         style="width:400px;">
+        <a href="images/319.jpg"><img width="400"
+             src="images/319.jpg"
+             alt="FIG. 3. PERSEUS AND ITS NEIGHBORING STARS"></a>
+
+        <p>FIG. 3. PERSEUS AND ITS NEIGHBORING STARS INCLUDING
+        ALGOL.</p>
+    </div>
+
+    <p>Most of the stars are white, but many are of a somewhat
+    ruddy hue. There are a few telescopic points which are
+    intensely red, some exhibit beautiful golden tints, while
+    others are blue or green.</p>
+
+    <p>There are some curious stars which regularly change their
+    brilliancy. Let me try to illustrate the nature of these
+    variables. Suppose that you were looking at a street gas-lamp
+    from a very long distance, so that it seemed a little twinkling
+    light; and suppose that some one was preparing to turn the
+    gas-cock up and down. Or, better still, imagine a little
+    machine which would act regularly so as to keep the light first
+    of all at its full brightness for two days and a half, and then
+    gradually turn it down until in three or four hours it declines
+    to a feeble glimmer. In this low state the light remains for
+    twenty minutes; then during three or four hours the gas is to
+    be slowly turned on again until it is full. In this condition
+    the light will remain for two days and a half, and then the
+    same series of changes is to recommence. This would be a very
+    odd form of gas-lamp. There would be periods of two days and a
+    half during which it would remain at its full; these would be
+    separated by intervals of about seven hours, when the gradual
+    turning down and turning up again would be in progress.</p>
+
+    <p>The imaginary gas-lamp is exactly paralleled by a star
+    Algol, in the constellation of Perseus (Fig. 3), which goes
+    through the series of changes I have indicated. Ordinarily
+    speaking, it is a bright star of the <span class=
+    "pagenum"><a id="page319"></a>[pg 319]</span> second magnitude, and,
+       whatever be the cause, the star performs its variations with
+       marvellous uniformity. In fact, Algol has always arrested
+       the attention of those who observed the heavens, and in
+       early times was looked on as the eye of a demon. There are
+       many other stars which also change their brilliancy. Most of
+       them require much longer periods than Algol, and sometimes a
+       new star which nobody has ever seen before will suddenly
+       kindle into brilliancy. It is now known that the bright star
+       Algol is attended by a dark companion. This dark star
+       sometimes comes between Algol and the observer and cuts off
+       the light. Thus it is that the diminution of brightness is
+       produced.</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>Double Stars.</b></p>
+
+    <p>Whenever you have a chance of looking at the heavens through
+    a telescope, you should ask to be shown what is called <i>a
+    double star</i>. There are many stars in the heavens which
+    present no remarkable appearance to the unaided eye, but which
+    a good telescope at once shows to be of quite a complex nature.
+    <span class="pagenum"><a id="page320"></a>[pg 320]</span> These are what we call
+       double stars, in which two quite distinct stars are placed
+       so close together that the unaided eye is unable to separate
+       them. Under the magnifying power of the telescope, however,
+       they are seen to be distinct. In order to give some notion
+       of what these objects are like, I shall briefly describe
+       three of them. The first lies in that best known
+       constellation, the Great Bear. If you look at his tail,
+       which consists of three stars, you will see that near the
+       middle one of the three a small star is situated; we call
+       this little star Alcor, but it is the brighter one near
+       Alcor to which I specially call your attention. The sharpest
+       eye would never suspect that it was composed of two stars
+       placed close together. Even a small telescope will, however,
+       show this to be the case, and this is the easiest and the
+       first observation that a young astronomer should make when
+       beginning to turn a telescope to the heavens. Of course you
+       will not imagine that I mean Alcor to be the second
+       component of the double star; it is the bright star near
+       Alcor which is the double. Here are two marbles, and these
+       marbles are fastened an inch apart. You can see them, of
+       course, to be separate; but if the pair were moved further
+       and further away, then you would soon not be able to
+       distinguish between them, though the actual distance between
+       the marbles had not altered. Look at these two wax tapers
+       which are now lighted; the little flames are an inch apart.
+       You would have to view them from a station a third of a mile
+       away if the distance between the two flames were to appear
+       the same as that between the two components of this double
+       star. Your eye would never be able to discriminate between
+       two <span class="pagenum"><a id="page321"></a>[pg 321]</span> lights only an inch apart
+       at so great a distance; a telescope would, however, enable
+       you to do so, and this is the reason why we have to use
+       telescopes to show us double stars.</p>
+
+    <p>You might look at that double star year after year
+    throughout the course of a long life without finding any
+    appreciable change in the relative positions of its components.
+    But we know that there is no such thing as rest in the
+    universe; even if you could balance a body so as to leave it
+    for a moment at rest, it would not stay there, for the simple
+    reason that all the bodies round it in every direction are
+    pulling at it, and it is certain that the pull in one direction
+    will preponderate, so that move it must. Especially is this
+    true in the case of two suns like those forming a double star.
+    Placed comparatively near each other they could not remain
+    permanently in that position; they must gradually draw together
+    and come into collision with an awful crash. There is only one
+    way by which such a disaster could be averted. That is by
+    making one of these stars revolve around the other just as the
+    earth revolves around the sun, or the moon revolves around the
+    earth. Some motion must, therefore, be going on in every
+    genuine double star, whether we have been able to see that
+    motion or not.</p>
+
+    <p>Let us now look at another double star of a different kind.
+    This time it is in the constellation of Gemini. The heavenly
+    twins are called Castor and Pollux. Of these, Castor is a very
+    beautiful double star, consisting of two bright points, a great
+    deal closer together than were those in the Great Bear;
+    consequently a better telescope is required for the purpose of
+    showing them <span class="pagenum"><a id="page322"></a>[pg 322]</span> separately. Castor has been
+       watched for many years, and it can be seen that one of these
+       stars is slowly revolving around the other; but it takes a
+       very long time, amounting to hundreds of years, for a
+       complete circuit to be accomplished. This seems very
+       astonishing, but when you remember how exceedingly far
+       Castor is, you will perceive that that pair of stars which
+       appear so close together that it requires a telescope to
+       show them apart must indeed be separated by hundreds of
+       millions of miles. Let us try to conceive our own system
+       transformed into a double star. If we took our outermost
+       planet&mdash;Neptune&mdash;and enlarged him a good deal, and
+       then heated him sufficiently to make him glow like a sun, he
+       would still continue to revolve round our sun at the same
+       distance, and thus a double star would be produced. An
+       inhabitant of Castor who turned his telescope towards us
+       would be able to see the sun as a star. He would not, of
+       course, be able to see the earth, but he might see Neptune
+       like another small star close to the sun. If generations of
+       astronomers in Castor continued their observations of our
+       system, they would find a binary star, of which one
+       component took a century and a half to go round the other.
+       Need we then be surprised that when we look at Castor we
+       observe movements that seem very slow?</p>
+
+    <p>There is often so much diffused light about the bright stars
+    seen in a telescope, and so much twinkling in some states of
+    the atmosphere, that stars appear to dance about in rather a
+    puzzling fashion, especially to one who is not accustomed to
+    astronomical observations. I remember hearing how a gentleman
+    once came to visit an observatory. The astronomer showed him
+    <span class="pagenum"><a id="page323"></a>[pg 323]</span> Castor through a powerful
+       telescope as a fine specimen of a double star, and then, by
+       way of improving his little lesson, the astronomer mentioned
+       that one of these stars was revolving around the other. "Oh,
+       yes," said the visitor, "I saw them going round and round in
+       the telescope." He would, however, have had to wait for a
+       few centuries with his eye to the instrument before he would
+       have been entitled to make this assertion.</p>
+
+    <p>Double stars also frequently delight us by giving
+    beautifully contrasted colors. I dare say you have often
+    noticed the red and the green lights that are used on railways
+    in the signal lamps. Imagine one of those red and one of those
+    green lights away far up in the sky and placed close together,
+    then you would have some idea of the appearance that a colored
+    double star presents, though, perhaps, I should add that the
+    hues in the heavenly bodies are not so vividly different as are
+    those which our railway people find necessary. There is a
+    particularly beautiful double star of this kind in the
+    constellation of the Swan. You could make an imitation of it by
+    boring two holes, with a red-hot needle, in a piece of card,
+    and then covering one of these holes with a small bit of the
+    topaz-colored gelatine with which Christmas crackers are made.
+    The other star is to be similarly colored with blue gelatine. A
+    slide made on this principle placed in the lantern gives a very
+    good representation of these two stars on the screen. There are
+    many other colored doubles besides this one; and, indeed, it is
+    noteworthy that we hardly ever find a blue or a green star by
+    itself in the sky; it is always as a member of one of these
+    pairs.</p><span class="pagenum"><a id="page324"></a>[pg 324]</span>
+
+    <p>&nbsp;</p>
+
+    <p><b>How We Find What the Stars are Made of.</b></p>
+
+    <p>Here is a piece of stone. If I wanted to know what it was
+    composed of, I should ask a chemist to tell me. He would take
+    it into his laboratory, and first crush it into powder, and
+    then, with his test tubes, and with the liquids which his
+    bottles contain, and his weighing scales, and other apparatus,
+    he would tell all about it; there is so much of this, and so
+    much of that, and plenty of this, and none at all of that. But
+    now, suppose you ask this chemist to tell you what the sun is
+    made of, or one of the stars. Of course, you have not a sample
+    of it to give him; how, then, can he possibly find out anything
+    about it? Well, he can tell you something, and this is the
+    wonderful discovery that I want to explain to you. We now put
+    down the gas, and I kindle a brilliant red light. Perhaps some
+    of those whom I see before me have occasionally ventured on the
+    somewhat dangerous practice of making fire-works. If there is
+    any boy here who has ever constructed sky-rockets, and put the
+    little balls into the top which are to burn with such vivid
+    colors when the explosion takes place, he will know that the
+    substance which tinged that fire red must have been strontium.
+    He will recognize it by the color; because strontium gives a
+    red light which nothing else will give. Here are some of these
+    lightning papers, as they are called; they are very pretty and
+    very harmless; and these, too, give brilliant red flashes as I
+    throw them. The red tint has, no doubt, been produced by
+    strontium also. You see we recognized the substance simply by
+    the color of the light it produced when
+          burning.</p><span class="pagenum"><a id="page325"></a>[pg 325]</span>
+
+    <p>Perhaps some of you have tried to make a ghost at Christmas
+    by dressing up in a sheet, and bearing in your hand a ladle
+    blazing with a mixture of common salt and spirits of wine, the
+    effect produced being a most ghastly one. Some mammas will
+    hardly thank me for this suggestion, unless I add that the
+    ghost must walk about cautiously, for otherwise the blazing
+    spirit would be very apt to produce conflagrations of a kind
+    more extensive than those intended. However, by the kindness of
+    Professor Dewar, I am enabled to show the phenomenon on a
+    splendid scale, and also free from all danger. I kindle a vivid
+    flame of an intensely yellow color, which I think the ladies
+    will unanimously agree is not at all becoming to their
+    complexions, while the pretty dresses have lost their variety
+    of colors. Here is a nice bouquet, and yet you can hardly
+    distinguish the green of the leaves from the brilliant colors
+    of the flowers, except by trifling differences of shade. Expose
+    to this light a number of pieces of variously colored ribbon,
+    pink and red and green and blue, and their beauty is gone; and
+    yet we are told that this yellow is a perfectly pure color; in
+    fact, the purest color that can be produced. I think we have to
+    be thankful that the light which our good sun sends us does not
+    possess purity of that description. There is one substance
+    which will produce that yellow light; it is a curious metal
+    called sodium&mdash;a metal so soft that you can cut it with a
+    knife, and so light that it will float on water; while, still
+    more strange, it actually takes fire the moment it is dropped
+    on the water. It is only in a chemical laboratory that you will
+    be likely to meet with the actual metallic sodium, yet in other
+    forms the <span class="pagenum"><a id="page326"></a>[pg 326]</span> substance is one of the
+       most abundant in nature. Indeed, common salt is nothing but
+       sodium closely united with a most poisonous gas, a few
+       respirations of which would kill you. But this strange metal
+       and this noxious gas, when united, become simply the salt
+       for our eggs at breakfast. This pure yellow light, wherever
+       it is seen, either in the flame of spirits of wine mixed
+       with salt or in that great blaze at which we have been
+       looking, is characteristic of sodium. Wherever you see that
+       particular kind of light, you know that sodium must have
+       been present in the body from which it came.</p>
+
+    <p>We have accordingly learned to recognize two substances,
+    namely, strontium and sodium, by the different lights which
+    they give out when burning. To these two metals we may add a
+    third. Here is a strip of white metallic ribbon. It is called
+    magnesium. It seems like a bit of tin at the first glance, but
+    indeed it is a very different substance from tin; for, look,
+    when I hold it in the spirit-lamp, the strip of metal
+    immediately takes fire, and burns with a white light so
+    dazzling that it pales the gas-flames to insignificance. There
+    is no other substance which will, when kindled, give that
+    particular kind of light which we see from magnesium. I can
+    recommend this little experiment as quite suitable for trying
+    at home; you can buy a bit of magnesium ribbon for a trifle at
+    the opticians; it cannot explode or do any harm, nor will you
+    get into any trouble with the authorities provided you hold it
+    when burning over a tray or a newspaper, so as to prevent the
+    white ashes from falling on the carpet.</p>
+
+    <p>There are, in nature, a number of simple bodies called
+    <span class="pagenum"><a id="page327"></a>[pg 327]</span> elements. Every one of
+       these, when ignited under suitable conditions, emits a light
+       which belongs to it alone, and by which it can be
+       distinguished from every other substance. I do not say that
+       we can try the experiments in the simple way I have here
+       indicated. Many of the materials will yield light which will
+       require to be studied by much more elaborate artifices than
+       those which have sufficed for us. But you will see that the
+       method affords a means of finding out the actual substances
+       present in the sun or in the stars. There is a practical
+       difficulty in the fact that each of the heavenly bodies
+       contains a number of different elements; so that in the
+       light it sends us the hues arising from distinct substances
+       are blended into one beam. The first thing to be done is to
+       get some way of splitting up a beam of light, so as to
+       discover the components of which it is made. You might have
+       a skein of silks of different hues tangled together, and
+       this would be like the sunbeam as we receive it in its
+       unsorted condition. How shall we untangle the light from the
+       sun or a star? I will show you by a simple experiment. Here
+       is a beam from the electric light; beautifully white and
+       bright, is it not? It looks so pure and simple, but yet that
+       beam is composed of all sorts of colors mingled together, in
+       such proportions as to form white light. I take a
+       wedge-shaped piece of glass called a prism, and when I
+       introduce it into the course of the beam, you see the
+       transformation that has taken place (Fig. 4). Instead of the
+       white light you have now all the colors of the
+       rainbow&mdash;red, orange, yellow, green, blue, indigo,
+       violet, marked by their initial letters in the figure. These
+       colors are very beautiful, but they are transient, for the
+       <span class="pagenum"><a id="page328"></a>[pg 328]</span> moment we take away the
+       prism they all unite again to form white light. You see what
+       the prism has done; it has bent all the light in passing
+       through it; but it is more effective in bending the blue
+       than the red, and consequently the blue is carried away much
+       further than the red. Such is the way in which we study the
+       composition of a heavenly body. We take a beam of its light,
+       we pass it through a prism, and immediately it is separated
+       into its components; then we compare what we find with the
+       lights given by the different elements, and thus we are
+       enabled to discover the substances which exist in the
+       distant object whose light we have examined. I do not mean
+       to say that the method is a simple one; all I am endeavoring
+       to show is a general outline of the way in which we have
+       discovered the materials present in the stars. The
+       instrument that is employed for this purpose is called the
+       spectroscope. And perhaps you may remember that name by
+       these lines, which I have heard from an astronomical
+       friend:&mdash;</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p>"Twinkle, twinkle, little star,</p>
+
+            <p>Now we find out what you are,</p>
+
+            <p>When unto the midnight sky,</p>
+
+            <p>We the spectroscope apply."</p>
+        </div>
+    </div>
+
+    <div class="figright"
+         style="width:400px;">
+        <a href="images/328.jpg"><img width="400"
+             src="images/328.jpg"
+             alt="FIG. 4. HOW A RAY OF LIGHT IS SPLIT UP."></a><br>
+        FIG. 4. HOW A RAY OF LIGHT IS SPLIT UP.
+    </div><span class="pagenum"><a id="page329"></a>[pg 329]</span>
+
+    <p>I am sure it will interest everybody to know that the
+    elements which the stars contain are not altogether different
+    from those of which the earth is made. It is true there may be
+    substances in the stars of which we know nothing here; but it
+    is certain that many of the most common elements on the earth
+    are present in the most distant bodies. I shall only mention
+    one, the metal iron. That useful substance has been found in
+    some of the stars which lie at almost incalculable distances
+    from the earth.</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>The Nebulæ.</b></p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/330-1.png"><img width="300"
+             src="images/330-1.png"
+             alt="FIG. 5. A GREAT REFLECTING TELESCOPE."></a><br>
+        FIG. 5. A GREAT REFLECTING TELESCOPE.
+    </div>
+
+    <p>In drawing towards the close of these lectures I must say a
+    few words about some dim and mysterious objects to which we
+    have not yet alluded. They are what are called nebulæ, or
+    little clouds; and in one sense they are justly called little,
+    for each of them occupies but a very small spot in the sky as
+    compared with that which would be filled by an ordinary cloud
+    in our air. The nebulæ are, however, objects of the most
+    stupendous proportions. Were our earth and thousands of
+    millions of bodies quite as big all put together, they would
+    not be nearly so great as one of these nebulæ. Astronomers
+    reckon up the various nebulæ by thousands, but I must add that
+    most of them are apparently faint and uninteresting. A nebula
+    is sometimes liable to be mistaken for a comet. The comet is,
+    as I have already explained, at once distinguished by the fact
+    that it is moving and changing its appearance from hour to
+    hour, while scores of years elapse without changes in the
+    aspect or position of a nebula. The most powerful telescopes
+    are employed in observing <span class="pagenum"><a name=
+    "page330"
+       id="page330"></a>[pg 330]</span> these faint objects. I take
+       this opportunity of showing a picture of an instrument
+       suitable for such observations. It is the great reflector of
+       the Paris Observatory (Fig. 5).</p>
+
+    <div class="figright"
+         style="width:350px;">
+        <a href="images/330-2.jpg"><img width="350"
+             src="images/330-2.jpg"
+             alt=
+           "FIG. 6. THE RING NEBULA IN LYRA, UNDER DIFFERENT TELESCOPIC POWERS."></a>
+
+        <p>FIG. 6. THE RING NEBULA IN LYRA, UNDER DIFFERENT
+        TELESCOPIC POWERS.</p>
+    </div>
+
+    <p>There are such multitudes of nebulæ that I can only show a
+    few of the more remarkable kinds. In Fig. 6 will be seen
+    pictures of a curious object in the constellation of Lyra seen
+    under different telescopic powers. This is a gigantic ring of
+    luminous gas. To judge of the size of this ring let us suppose
+    that a railway were laid across it, and the train you entered
+    at one side was not to stop until it reached the other side,
+    how long do you think this journey would require? I recollect
+    some time ago a picture in <i>Punch</i> which showed a train
+    about to start from London to Brighton, and the guard walking
+    up and down announcing to the passengers the alarming fact that
+    "this train stops nowhere." An old gentleman was seen
+    <span class="pagenum"><a id="page331"></a>[pg 331]</span> vainly gesticulating out of
+       the window and imploring to be let out ere the frightful
+       journey was commenced. In the nebular railway the passengers
+       would almost require such a warning.</p>
+
+    <p>Let the train start at a speed of a mile a minute, you would
+    think, surely, that it must soon cross the ring. But the
+    minutes pass, an hour has elapsed; so the distance must be
+    sixty miles at all events. The hours creep on into days, the
+    days advance into years, and still the train goes on. The years
+    would lengthen out into centuries, and even when the train had
+    been rushing on for a thousand years with an unabated speed of
+    a mile a minute, the journey would certainly not have been
+    completed. Nor do I venture to say what ages must elapse ere
+    the terminus at the other side of the ring nebula would be
+    reached.</p>
+
+    <p>A cluster of stars viewed in a small telescope will often
+    seem like a nebula, for the rays of the stars become blended. A
+    powerful telescope will, however, dispel the illusion and
+    reveal the separate stars. It was, therefore, thought that all
+    the nebulæ might be merely clusters so exceedingly remote that
+    our mightiest instruments failed to resolve them into stars.
+    But this is now known not to be the case. Many of these objects
+    are really masses of glowing gas; such are, for instance, the
+    ring nebulæ, of which I have just spoken, and the form of which
+    I can simulate by a pretty experiment.</p>
+
+    <p>We take a large box with a round hole cut in one face, and a
+    canvas back at the opposite side. I first fill this box with
+    smoke, and there are different ways of doing so. Burning brown
+    paper does not answer <span class="pagenum"><a id="page332"></a>[pg 332]</span> well, because the supply of
+       smoke is too irregular and the paper itself is apt to blaze.
+       A little bit of phosphorus set on fire yields copious smoke,
+       but it would be apt to make people cough, and, besides,
+       phosphorus is a dangerous thing to handle incautiously, and
+       I do not want to suggest anything which might be productive
+       of disaster if the experiment was repeated at home. A little
+       wisp of hay, slightly damped and lighted, will safely yield
+       a sufficient supply, and you need not have an elaborate box
+       like this; any kind of old packing-case, or even a bandbox
+       with a duster stretched across its open top and a round hole
+       cut in the bottom, will answer capitally. While I have been
+       speaking, my assistant has kindly filled this box with
+       smoke, and in order to have a sufficient supply, and one
+       which shall be as little disagreeable as possible, he has
+       mixed together the fumes of hydrochloric acid and ammonia
+       from two retorts shown in Fig. 7. A still simpler way of
+       doing the same thing is to put a little common salt in a
+       saucer and pour over it a little oil of vitriol; this is put
+       into the box, and over the floor of the box common
+       smelling-salts is to be scattered. You see there are dense
+       volumes of white smoke escaping from every corner of the
+       box. I uncover the opening and give a push to the canvas,
+       and you see a beautiful ring flying across the room; another
+       ring and another follows. If you were near <span class=
+       "pagenum"><a id="page333"></a>[pg 333]</span> enough to feel the ring,
+       you would experience a little puff of wind; I can show this
+       by blowing out a candle which is at the other end of the
+       table. These rings are made by the air which goes into a
+       sort of eddy as it passes through the hole. All the smoke
+       does is to render the air visible. The smoke-ring is indeed
+       quite elastic. If we send a second ring hurriedly after the
+       first, we can produce a collision, and you see each of the
+       two rings remains unbroken, though both are quivering from
+       the effects of the blow. They are beautifully shown along
+       the beam of the electric lamp, or, better still, along a
+       sunbeam.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/332.png"><img width="300"
+             src="images/332.png"
+             alt="FIG. 7. HOW TO MAKE THE SMOKE RINGS."></a><br>
+        FIG. 7. HOW TO MAKE THE SMOKE RINGS.
+    </div>
+
+    <p>We can make many experiments with smoke-rings. Here, for
+    instance, I take an empty box, so far as smoke is concerned,
+    but air-rings can be driven forth from it, though you cannot
+    see them, but you can feel them even at the other side of the
+    room, and they will, as you see, blow out a candle. I can also
+    shoot invisible air-rings at a column of smoke, and when the
+    missile strikes the smoke it produces a little commotion and
+    emerges on the other side, carrying with it enough of the smoke
+    to render itself visible, while the solid black looking ring of
+    air is seen in the interior. Still more striking is another way
+    of producing these rings, for I charge this box with ammonia,
+    and the rings from it you cannot see. There is a column of the
+    vapor of hydrochloric acid, that also you cannot see; but when
+    the visible ring enters the invisible column, then a sudden
+    union takes place between the vapor of the ammonia and the
+    vapor of the hydrochloric acid; the result is a solid white
+    substance in extremely fine dust which renders the ring
+    instantly visible.</p><span class="pagenum"><a id="page334"></a>[pg 334]</span>
+
+    <p>&nbsp;</p>
+
+    <p><b>What the Nebulæ are made of.</b></p>
+
+    <p>There is a fundamental difference between the illumination
+    of these little rings that I have shown you and the great rings
+    in the heavens. I had to illuminate our smoke with the help of
+    the electric light, for, unless I had done so, you would not
+    have been able to see them. This white substance formed by the
+    union of ammonia and hydrochloric acid has, of course, no more
+    light of its own than a piece of chalk; it requires other light
+    falling upon it to make it visible. Were the ring nebula in
+    Lyra composed of this material, we could not see it. The
+    sunlight which illuminates the planets might, of course, light
+    up such an object as the ring, if it wrere comparatively near
+    us; but Lyra is at such a stupendous distance that any light
+    which the sun could send out there would be just as feeble as
+    the light we receive from a fixed star. Should we be able to
+    show our smoke-rings, for instance, if, instead of having the
+    electric light, I merely cut a hole in the ceiling and allowed
+    the feeble twinkle of a star in the Great Bear to shine
+    through? In a similar way the sunbeams would be utterly
+    powerless to effect any illumination of objects in these
+    stellar distances. If the sun were to be extinguished
+    altogether, the calamity would no doubt be a very dire one so
+    far as we are concerned, but the effect on the other celestial
+    bodies (moon and planets excepted) would be of the slightest
+    possible description. All the stars of heaven would continue to
+    shine as before. Not a point in one of the constellations
+    wrould be altered, not a variation in the brightness, not a
+    change in the hue of any star could <span class=
+    "pagenum"><a id="page335"></a>[pg 335]</span> be noticed. The thousands
+       of nebulæ and clusters would be absolutely unaltered; in
+       fact, the total extinction of the sun would be hardly
+       remarked in the newspapers published in the Pleiades or in
+       Orion. There might possibly be a little line somewhere in an
+       odd corner to the effect "Mr. So-and-So, our well-known
+       astronomer, has noticed that a tiny star, inconspicuous to
+       the eye, and absolutely of no importance whatever, has now
+       become invisible."</p>
+
+    <p>If, therefore, it be not the sun which lights up this
+    nebula, where else can be the source of its illumination? There
+    can be no other star in the neighborhood adequate to the
+    purpose, for, of course, such an object would be brilliant to
+    us if it were large enough and bright enough to impart
+    sufficient illumination to the nebula. It would be absurd to
+    say that you could see a man's face by the light of a candle
+    while the candle itself was too faint or too distant to be
+    visible. The actual facts are, of course, the other way; the
+    candle might be visible, when it was impossible to discern the
+    face which it lighted.</p>
+
+    <p>Hence we learn that the ring nebula must shine by some light
+    of its own, and now we have to consider how it can be possible
+    for such material to be self-luminous. The light of a nebula
+    does not seem to be like flame; it can, perhaps, be better
+    represented by the pretty electrical experiment with Geissler's
+    tubes. These are glass vessels of various shapes, and they are
+    all very nearly empty, as you will understand when I tell you
+    the way in which they have been prepared. A little gas was
+    allowed into each tube, and then almost all the gas was taken
+    out again, so that only a mere <span class=
+       "pagenum"><a id="page336"></a>[pg 336]</span> trace was left. I pass a
+       current of electricity through these tubes, and now you see
+       they are glowing with beautiful colors. The different gases
+       give out lights of different hues, and the optician has
+       exerted his skill so as to make the effect as beautiful as
+       possible. The electricity, in passing through these tubes,
+       heats the gas which they contain, and makes it glow; and
+       just as this gas can, when heated sufficiently, give out
+       light, so does the great nebula, which is a mass of gas
+       poised in space, become visible in virtue of the heat which
+       it contains.</p>
+
+    <p>We are not left quite in doubt as to the constitution of
+    these gaseous nebulæ, for we can submit their light to the
+    prism in the way I explained when we were speaking of the
+    stars. Distant though that ring in Lyra may be, it is
+    interesting to learn that the ingredients from which it is made
+    are not entirely different from substances we know on our
+    earth. The water in this glass, and every drop of water, is
+    formed by the union of two gases, of which one is hydrogen.
+    This is an extremely light material, as you see by a little
+    balloon which ascends so prettily when filled with it. Hydrogen
+    also burns very readily, though the flame is almost invisible.
+    When I blow a jet of oxygen through the hydrogen, I produce a
+    little flame with a very intense heat. For instance, I hold a
+    steel pen in the flame, and it glows and sputters, and falls
+    down in white-hot drops. It is needless to say that, as a
+    constituent of water, hydrogen is one of the most important
+    elements on this earth. It is, therefore, of interest to learn
+    that hydrogen in some form or other is a constituent of the
+    most distant objects in space that the telescope has
+    revealed.</p><span class="pagenum"><a id="page337"></a>[pg 337]</span>
+
+    <p>&nbsp;</p>
+
+    <p><b>Photographing the Nebulæ.</b></p>
+
+    <div class="figright"
+         style="width:300px;">
+        <a href="images/337.jpg"><img width="300"
+             src="images/337.jpg"
+             alt="FIG. 8. THE PLEIADES."></a><br>
+        FIG. 8. THE PLEIADES.
+    </div>
+
+    <p>Of late years we have learned a great deal about nebulæ, by
+    the help which photography has given to us. Look at this group
+    of stars which constitutes that beautiful little configuration
+    known as the Pleiades (Fig. 8). It looks like a miniature
+    representation of the Great Bear; in fact, it would be far more
+    appropriate to call the Pleiades the Little Bear than to apply
+    that title to another quite different constellation, as has
+    unfortunately been done. The Pleiades form a group containing
+    six or seven stars visible to the ordinary eye, though persons
+    endowed with exceptionally good vision can usually see a few
+    more. In an opera-glass the Pleiades becomes a beautiful
+    spectacle, though in a large telescope the stars appear too far
+    apart to make a really effective cluster. When Mr. Roberts took
+    a photograph of the Pleiades he placed a highly sensitive plate
+    in his telescope, and on that plate the Pleiades engraved their
+    picture with their own light. He left the plate exposed for
+    hours, and on developing it not only were the stars seen, but
+    there were also patches of faint light due to the presence of
+    nebulæ. It could not be said that the objects on the plate were
+    fallacious, for another photograph was taken, when the same
+    appearances were reproduced.</p><span class=
+       "pagenum"><a id="page338"></a>[pg 338]</span>
+
+    <p>When we look at that pretty group of stars which has
+    attracted admiration during all time, we are to think that some
+    of those stars are merely the bright points in a vast nebula,
+    invisible to our unaided eyes or even to our mighty telescopes,
+    though capable of recording its trace on the photographic
+    plate. Does not this give us a greatly increased notion of the
+    extent of the universe, when we reflect that by photography we
+    are enabled to see much which the mightiest of telescopes had
+    previously failed to disclose?</p>
+
+    <p>Of all the nebulæ, numbering some thousands, there is but a
+    single one which can be seen without a telescope. It is in the
+    constellation of Andromeda, and on a clear dark night can just
+    be seen with the unaided eye as a faint stain of light on the
+    sky. It has happened before now that persons noticing this
+    nebula for the first time have thought they had discovered a
+    comet. I would like you to try and find out this object for
+    yourselves.</p>
+
+    <p>If you look at it with an opera-glass it appears to be
+    distinctly elongated. You can see more of its structure when
+    you view it in larger instruments, but its nature was never
+    made clear until some beautiful photographs were taken by Mr.
+    Roberts (Fig. 9). Unfortunately, the nebula in Andromeda has
+    not been placed in the best position for its portrait from our
+    point of view. It seems as if it were a rather flat-shaped
+    object, turned nearly edgewise towards us. To look at the
+    pattern on a plate, you would naturally hold the plate so as to
+    be able to look at it squarely. The pattern would not be seen
+    well if the plate were so tilted that its edge was turned
+    towards you. That seems to be nearly the way <span class=
+    "pagenum"><a id="page339"></a>[pg 339]</span> in which we are forced to
+       view the nebula in Andromeda. We can trace in the photograph
+       some divisions extending entirely round the nebula, showing
+       that it seems to be formed of a series of rings; and there
+       are some outlying portions which form part of the same
+       system. Truly this is a marvellous object. It is impossible
+       for us to form any conception of the true dimensions of this
+       gigantic nebula; it is so far off that we have never yet
+       been able to determine its distance. Indeed, I may take this
+       opportunity of remarking that no astronomer has yet
+       succeeded in ascertaining the distance of any nebula.
+       Everything, however, points to the conclusion that they are
+       at least as far as the stars.</p>
+
+    <div class="figright"
+         style="width:300px;">
+        <a href="images/339.jpg"><img width="300"
+             src="images/339.jpg"
+             alt="FIG. 9. THE GREAT NEBULA IN ANDROMEDA."></a><br>
+        FIG. 9. THE GREAT NEBULA IN ANDROMEDA.
+    </div>
+
+    <p>It is almost impossible to apply the methods which we use in
+    finding the distance of a star to the discovery of the distance
+    of the nebulæ. These flimsy bodies are usually too ill-defined
+    to admit of being measured with the precision and delicacy
+    required for the determination of distance. The measurements
+    necessary for this purpose can only be made from one star-like
+    point to another similar point. If we could choose a star in
+    <span class="pagenum"><a id="page340"></a>[pg 340]</span> the nebula and determine
+       its distance, then of course, we have the distance of the
+       nebula itself; but the difficulty is that we have, in
+       general, no means of knowing whether the star does actually
+       lie in the object. It may, for anything we can tell, lie
+       billions of miles nearer to us, or billions of miles further
+       off, and by merely happening to lie in the line of sight,
+       appear to glimmer in the nebula itself.</p>
+
+    <p>If we have any assurance that the star is surrounded by a
+    mass of this glowing vapor, then it may be possible to measure
+    that nebula's distance. It will occasionally happen that
+    grounds can be found for believing that a star which appears to
+    be in the glowing gas does veritably lie therein, and is not
+    merely seen in the same direction. There are hundreds of stars
+    visible in a good drawing or a good photograph of the famous
+    object in Andromeda, and doubtless large numbers of these are
+    merely stars which happen to lie in the same line of sight. The
+    peculiar circumstances attending the history of one star seem,
+    however, to warrant us in making the assumption that it was
+    certainly in the nebula. The history of this star is a
+    remarkable one. It suddenly kindled from invisibility into
+    brilliancy. How is a change so rapid in the lustre of a star to
+    be accounted for? In a few days its brightness had undergone an
+    extraordinary increase. Of course, this does not tell us for
+    certain that the star lay in the glowing gas; but the most
+    rational explanation that I have heard offered of this
+    occurrence is that due, I believe, to my friend Mr. Monck. He
+    has suggested that the sudden outbreak in brilliancy might be
+    accounted for on the same principles as those by which we
+    explain the <span class="pagenum"><a id="page341"></a>[pg 341]</span> ignition of meteors in our
+       atmosphere. If a dark star, moving along with terrific speed
+       through space, were suddenly to plunge into a dense region
+       of the nebula, heat and light must be evolved in sufficient
+       abundance to transform the star into a brilliant object. If,
+       therefore, we knew the distance of this star at the time it
+       was in Andromeda, we should, of course, learn the distance
+       of that interesting object. This has been attempted, and it
+       has thus been proved that the Great Nebula must be very much
+       further from us than is that star of whose distance I
+       attempted some time ago to give you a notion.</p>
+
+    <div class="figright"
+         style="width:350px;">
+        <a href="images/341.jpg"><img width="350"
+             src="images/341.jpg"
+             alt=
+           "FIG. 10. THE SOLAR SYSTEM AS COMPARED WITH A GREAT NEBULA."></a><br>
+        FIG. 10. THE SOLAR SYSTEM AS COMPARED WITH A GREAT NEBULA.
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p>
+
+    <p>We thus realize the enormous size of the Great Nebula. It
+    appears that if, on a map of this object, we were to lay down,
+    accurately to scale, a map of the solar system, putting the sun
+    in the centre and all the planets around their true proportions
+    out to the boundary traced by Neptune, this area, vast though
+    it is, would be a mere speck on the drawing of the object. Our
+    system would have to be enormously bigger before it sufficed to
+    cover anything like the area of the sky included in one of
+    these great objects. Here is a sketch of a nebula, Fig. 10, and
+    near I have marked a dot, which is to indicate our solar
+    system. We may feel confident that the Great Nebula is at the
+    very least as mighty as this proportion would
+    indicate.</p><br>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="page342"></a>[pg 342]</span>
+
+    <h2>RAIN AND SNOW</h2>
+
+    <h4>(<span class="sc">From The Forms of Water.</span>)</h4>
+
+    <h3><span class="sc">By</span> JOHN TYNDALL.</h3>
+
+    <p>&nbsp;</p>
+    <hr class="short">
+
+    <p><b>Oceanic Distillation.</b></p>
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/342.png"><img width="200"
+             src="images/342.png"
+             alt="SNOW CRYSTALS."></a>SNOW CRYSTALS.
+    </div>
+
+    <p>At the equator, and within certain limits north and south of
+    it, the sun at certain periods of the year is directly overhead
+    at noon. These limits are called the Tropics of Cancer and of
+    Capricorn. Upon the belt comprised between these two circles
+    the sun's rays fall with their mightiest power; for here they
+    shoot directly downwards, and heat both earth and sea more than
+    when they strike slantingly.</p>
+
+    <p>When the vertical sunbeams strike the land they heat it, and
+    the air in contact with the hot soil becomes heated in turn.
+    But when heated the air expands, and when it expands it becomes
+    lighter. This lighter air rises, like wood plunged into water,
+    through the heavier air overhead.</p>
+
+    <p>When the sunbeams fall upon the sea the water is warmed,
+    though not so much as the land. The warmed water expands,
+    becomes thereby lighter, and therefore continues to float upon
+    the top. This upper layer of <span class="pagenum"><a name=
+    "page343"
+       id="page343"></a>[pg 343]</span> water warms to some extent
+       the air in contact with it, but it also sends up a quantity
+       of aqueous vapor, which being far lighter than air, helps
+       the latter to rise. Thus both from the land and from the sea
+       we have ascending currents established by the action of the
+       sun.</p>
+
+    <p>When they reach a certain elevation in the atmosphere, these
+    currents divide and flow, part towards the north and part
+    towards the south; while from the north and the south a flow of
+    heavier and colder air sets in to supply the place of the
+    ascending warm air.</p>
+
+    <p>Incessant circulation is thus established in the atmosphere.
+    The equatorial air and vapor flow above towards the north and
+    south poles, while the polar air flows below towards the
+    equator. The two currents of air thus established are called
+    the upper and the lower trade winds.</p>
+
+    <p>But before the air returns from the poles great changes have
+    occurred. For the air as it quitted the equatorial regions was
+    laden with aqueous vapor, which could not subsist in the cold
+    polar regions. It is there precipitated, falling sometimes as
+    rain, or more commonly as snow. The land near the pole is
+    covered with this snow, which gives birth to vast glaciers.</p>
+
+    <p>It is necessary that you should have a perfectly clear view
+    of this process, for great mistakes have been made regarding
+    the manner in which glaciers are related to the heat of the
+    sun.</p>
+
+    <p>It was supposed that if the sun's heat were diminished,
+    greater glaciers than those now existing would
+          <span class="pagenum"><a id="page344"></a>[pg 344]</span> be produced. But the
+       lessening of the sun's heat would infallibly diminish the
+       quantity of aqueous vapor, and thus cut off the glaciers at
+       their source. A brief illustration will complete your
+       knowledge here.</p>
+
+    <p>In the process of ordinary distillation, the liquid to be
+    distilled is heated and converted into vapor in one vessel, and
+    chilled and reconverted into liquid in another. What has just
+    been stated renders it plain that the earth and its atmosphere
+    constitute a vast distilling apparatus in which the equatorial
+    ocean plays the part of the boiler, and the chill regions of
+    the poles the part of the condenser. In this process of
+    distillation <i>heat</i> plays quite as necessary a part as
+    <i>cold</i>, and before Bishop Heber could speak of
+    "Greenland's icy mountains," the equatorial ocean had to be
+    warmed by the sun. We shall have more to say upon this question
+    afterwards.</p>
+
+    <p>The heating of the tropical air by the sun is
+    <i>indirect</i>. The solar beams have scarcely any power to
+    heat the air through which they pass; but they heat the land
+    and ocean, and these communicate their heat to the air in
+    contact with them. The air and vapor start upwards charged with
+    the heat thus communicated.</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>Tropical Rains.</b></p>
+
+    <p>But long before the air and vapor from the equator reach the
+    poles, precipitation occurs. Wherever a humid warm wind mixes
+    with a cold dry one, rain falls. Indeed the heaviest rains
+    occur at those places where the sun is vertically overhead. We
+    must enquire a little more closely into their
+    origin.</p><span class="pagenum"><a id="page345"></a>[pg 345]</span>
+
+    <p>Fill a bladder about two-thirds full of air at the sea
+    level, and take it to the summit of Mount Blanc. As you ascend,
+    the bladder becomes more and more distended; at the top of the
+    mountain it is fully distended, and has evidently to bear a
+    pressure from within. Returning to the sea level you find that
+    the tightness disappears, the bladder finally appearing as
+    flaccid as at first.</p>
+
+    <p>The reason is plain. At the sea level the air within the
+    bladder has to bear the pressure of the whole atmosphere, being
+    thereby squeezed into a comparatively small volume. In
+    ascending the mountain, you leave more and more of the
+    atmosphere behind; the pressure becomes less and less, and by
+    its expansive force the air within the bladder swells as the
+    outside pressure is diminished. At the top of the mountain the
+    expansion is quite sufficient to render the bladder tight, the
+    pressure within being then actually greater than the pressure
+    without. By means of an air-pump we can show the expansion of a
+    balloon partly filled with air, when the external pressure has
+    been in part removed.</p>
+
+    <p>But why do I dwell upon this? Simply to make plain to you
+    that the <i>unconfined air</i>, heated at the earth's surface,
+    and ascending by its lightness, must expand more and more the
+    higher it rises in the atmosphere.</p>
+
+    <p>And now I have to introduce to you a new fact, towards the
+    statement of which I have been working for some time. It is
+    this: <i>The ascending air is chilled by its expansion</i>.
+    Indeed this chilling is one source of the coldness of the
+    higher atmospheric regions. And <span class=
+       "pagenum"><a id="page346"></a>[pg 346]</span> now fix your eye upon those
+       mixed currents of air and aqueous vapor which rise from the
+       warm tropical ocean. They start with plenty of heat to
+       preserve the vapor as vapor; but as they rise they come into
+       regions already chilled, and they are still further chilled
+       by their own expansion. The consequence might be foreseen.
+       The load of vapor is in great part precipitated, dense
+       clouds are formed, their particles coalesce to rain-drops,
+       which descend daily in gushes so profuse that the word
+       "torrential" is used to express the copiousness of the
+       rainfall. I could show you this chilling by expansion, and
+       also the consequent precipitation of clouds.</p>
+
+    <p>Thus long before the air from the equator reaches the poles
+    its vapor is in great part removed from it, having redescended
+    to the earth as rain. Still a good quantity of the vapor is
+    carried forward, which yields hail, rain, and snow in northern
+    and southern lands.</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>Mountain Condensers.</b></p>
+
+    <p>To complete our view of the process of atmospheric
+    precipitation we must take into account the action of
+    mountains. Imagine a south-west wind blowing across the
+    Atlantic towards Ireland. In its passage it charges itself with
+    aqueous vapor. In the south of Ireland it encounters the
+    mountains of Kerry: the highest of these is Magillicuddy's
+    Reeks, near Killarney. Now the lowest stratum of this Atlantic
+    wind is that which is most fully charged with vapor. When it
+    encounters the base of the Kerry Mountains it is tilted up and
+    flows bodily over them. Its load of vapor is therefore carried
+    to a height, it expands on reaching the height,
+          <span class="pagenum"><a id="page347"></a>[pg 347]</span> it is chilled in
+       consequence of the expansion, and comes down in copious
+       showers of rain. From this, in fact, arises the luxuriant
+       vegetation of Killarney; to this, indeed, the lakes owe
+       their water supply. The cold crests of the mountains also
+       aid in the work of condensation.</p>
+
+    <p>Note the consequence. There is a town called Cahirciveen to
+    the south-west of Magillicuddy's Reeks, at which observations
+    of the rainfall have been made, and a good distance farther to
+    the north-east, right in the course of the south-west wind
+    there is another town, called Portarlington, at which
+    observations of rainfall have also been made. But before the
+    wind reaches the latter station it has passed over the
+    mountains of Kerry and left a great portion of its moisture
+    behind it. What is the result? At Cahirciveen, as shown by Dr.
+    Lloyd, the rainfall amounts to fifty-nine inches in a year,
+    while at Portarlington it is only twenty-one inches.</p>
+
+    <p>Again, you may sometimes descend from the Alps when the fall
+    of rain and snow is heavy and incessant, into Italy, and find
+    the sky over the plains of Lombardy blue and cloudless, the
+    wind at the same time <i>blowing over the plain towards the
+    Alps</i>. Below the wind is hot enough to keep its vapor in a
+    perfectly transparent state; but it meets the mountains, is
+    tilted up, expanded, and chilled. The cold of the higher
+    summits also helps the chill. The consequence is that the vapor
+    is precipitated as rain or snow, thus producing bad weather
+    upon the heights, while the plains below, flooded with the same
+    air, enjoy the aspect of the unclouded summer sun. Clouds
+    blowing <i>from</i> the <span class="pagenum"><a id="page348"></a>[pg 348]</span> Alps are also sometimes
+       dissolved over the plains of Lombardy.</p>
+
+    <p>In connection with the formation of clouds by mountains, one
+    particularly instructive effect may be here noticed. You
+    frequently see a streamer of cloud many hundred yards in length
+    drawn out from an Alpine peak. Its steadiness appears perfect,
+    though a strong wind may be blowing at the same time over the
+    mountain head. Why is the cloud not blown away? It <i>is</i>
+    blown away; its permanence is only apparent. At one end it is
+    incessantly dissolved; at the other end it is incessantly
+    renewed: supply and consumption being thus equalized, the cloud
+    appears as changeless as the mountain to which it seems to
+    cling. When the red sun of the evening shines upon these
+    cloud-streamers they resemble vast torches with their flames
+    blown through the air.</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>Architecture of Snow.</b></p>
+
+    <p>We now resemble persons who have climbed a difficult peak,
+    and thereby earned the enjoyment of a wide prospect. Having
+    made ourselves masters of the conditions necessary to the
+    production of mountain snow, we are able to take a
+    comprehensive and intelligent view of the phenomena of
+    glaciers.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/348.png"><img width="300"
+             src="images/348.png"
+             alt="SNOW CRYSTALS."></a><br>
+        SNOW CRYSTALS.
+    </div>
+
+    <p>A few words are still necessary as to the formation of snow.
+    The molecules and atoms of all substances, when allowed free
+    play, build themselves into definite <span class=
+    "pagenum"><a id="page349"></a>[pg 349]</span> and, for the most part,
+       beautiful forms called crystals. Iron, copper, gold, silver,
+       lead, sulphur, when melted and permitted to cool gradually,
+       all show this crystallizing power. The metal bismuth shows
+       it in a particularly striking manner, and when properly
+       fused and solidified, self-built crystals of great size and
+       beauty are formed of this metal.</p>
+
+    <table>
+        <tr>
+            <td>
+                <div class="figleft"
+                     style="width:275px;">
+                    <a href="images/349-1.png"><img width="275"
+                         src="images/349-1.png"
+                         alt="SNOW-STAR."></a><br>
+                    SNOW-STAR.
+                </div>
+            </td>
+
+            <td>
+                <div class="figright"
+                     style="width:275px;">
+                    <a href="images/349-2.png"><img width="275"
+                         src="images/349-2.png"
+                         alt="SNOW-STAR."></a><br>
+                    SNOW-STAR.
+                </div>
+            </td>
+        </tr>
+    </table>
+
+    <p>If you dissolve salt-petre in water, and allow the solution
+    to evaporate slowly, you may obtain large crystals, for no
+    portion of the salt is converted into vapor. The water of our
+    atmosphere is fresh though it is derived from the salt sea.
+    Sugar dissolved in water, and permitted to evaporate, yields
+    crystals of sugar-candy. Alum readily crystallizes in the same
+    way. Flints dissolved, as they sometimes are in nature, and
+    permitted to crystallize, yield the prisms and pyramids of rock
+    crystal. Chalk dissolved and crystallized yields Iceland spar.
+    The diamond is <span class="pagenum"><a id="page350"></a>[pg 350]</span> crystallized carbon. All
+       our precious stones, the ruby, sapphire, beryl, topaz,
+       emerald, are all examples of this crystallizing power.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/350.png"><img width="300"
+             src="images/350.png"
+             alt="SNOW-STAR."></a><br>
+        SNOW-STAR.
+    </div>
+
+    <p>You have heard of the force of gravitation, and you know
+    that it consists of an attraction of every particle of matter
+    for every other particle. You know that planets and moons are
+    held in their orbits by this attraction. But gravitation is a
+    very simple affair compared to the force, or rather forces, of
+    crystallization. For here the ultimate particles of matter,
+    inconceivably small as they are, show themselves possessed of
+    attractive and repellent poles, by the mutual action of which
+    the shape and structure of the crystal are determined. In the
+    solid condition the attracting poles are rigidly locked
+    together; but if sufficient heat be applied the bond of union
+    is dissolved, and in the state of fusion the poles are pushed
+    so far asunder as to be practically out of each other's range.
+    The natural tendency of the molecules to build themselves
+    together is thus neutralized.</p>
+
+    <p>This is the case with water, which as a liquid is to all
+    appearance formless. When sufficiently cooled the molecules are
+    brought within the play of the crystallizing force, and they
+    then arrange themselves in forms of indescribable beauty. When
+    snow is produced in <span class="pagenum"><a id="page351"></a>[pg 351]</span> calm air, the icy particles
+       build themselves into beautiful stellar shapes, each star
+       possessing six rays. There is no deviation from this type,
+       though in other respects the appearances of the snow-stars
+       are infinitely various. In the polar regions these exquisite
+       forms were observed by Dr. Scoresby, who gave numerous
+       drawings of them. I have observed them in mid-winter filling
+       the air, and loading the slopes of the Alps. But in England
+       they are also to be seen, and no words of mine could convey
+       so vivid an impression of their beauty as the annexed
+       drawings of a few of them, executed at Greenwich by Mr.
+       Glaisher.</p>
+
+    <div class="figright"
+         style="width:300px;">
+        <a href="images/351.png"><img width="300"
+             src="images/351.png"
+             alt="SNOW-STAR."></a><br>
+        SNOW-STAR.
+    </div>
+
+    <p>It is worth pausing to think what wonderful work is going on
+    in the atmosphere during the formation and descent of every
+    snow-shower; what building power is brought into play! and how
+    imperfect seem the productions of human minds and hands when
+    compared with those formed by the blind forces of nature!</p>
+
+    <p>But who ventures to call the forces of nature blind? In
+    reality, when we speak thus we are describing our own
+    condition. The blindness is ours; and what we really ought to
+    say, and to confess, is that our powers are absolutely unable
+    to comprehend either the origin or the end of the operations of
+    nature.</p>
+
+    <p>But while we thus acknowledge our limits, there is
+    <span class="pagenum"><a id="page352"></a>[pg 352]</span> also reason for wonder at
+       the extent to which science has mastered the system of
+       nature. From age to age, and from generation to generation,
+       fact has been added to fact, and law to law, the true method
+       and order of the Universe being thereby more and more
+       revealed. In doing this science has encountered and
+       overthrown various forms of superstition and deceit, of
+       credulity and imposture. But the world continually produces
+       weak persons and wicked persons; and as long as they
+       continue to exist side by side, as they do in this our day,
+       very debasing beliefs will also continue to infest the
+       world.</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>Atomic Poles.</b></p>
+
+    <p>"What did I mean when, a few moments ago I spoke of
+    attracting and repellent poles?" Let me try to answer this
+    question. You know that astronomers and geographers speak of
+    the earth's poles, and you have also heard of magnetic poles,
+    the poles of a magnet being the points at which the attraction
+    and repulsion of the magnet are as it were concentrated.</p>
+
+    <p>Every magnet possesses two such poles; and if iron filings
+    be scattered over a magnet, each particle becomes also endowed
+    with two poles. Suppose such particles devoid of weight and
+    floating in our atmosphere, what must occur when they come near
+    each other? Manifestly the repellent poles will retreat from
+    each other, while the attractive poles will approach and
+    finally lock themselves together. And supposing the particles,
+    instead of a single pair, to possess several pairs of poles
+    arranged at definite points over their surfaces; you can then
+    picture them, in obedience to <span class="pagenum"><a name=
+    "page353"
+       id="page353"></a>[pg 353]</span> their mutual attractions
+       and repulsions, building themselves together to form masses
+       of definite shape and structure.</p>
+
+    <p>Imagine the molecules of water in calm cold air to be gifted
+    with poles of this description, which compel the particles to
+    lay themselves together in a definite order, and you have
+    before your mind's eye the unseen architecture which finally
+    produces the visible and beautiful crystals of the snow. Thus
+    our first notions and conceptions of poles are obtained from
+    the sight of our eyes in looking at the effects of magnetism;
+    and we then transfer these notions and conceptions to particles
+    which no eye has ever seen. The power by which we thus picture
+    to ourselves effects beyond the range of the senses is what
+    philosophers call the Imagination, and in the effort of the
+    mind to seize upon the unseen architecture of crystals, we have
+    an example of the "scientific use" of this faculty. Without
+    imagination we might have <i>critical</i> power, but not
+    <i>creative</i> power in science.</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>Architecture of Lake Ice.</b></p>
+
+    <p>We have thus made ourselves acquainted with the beautiful
+    snow-flowers self-constructed by the molecules of water in
+    calm, cold air. Do the molecules show this architectural power
+    when ordinary water is frozen? What, for example, is the
+    structure of the ice over which we skate in winter? Quite as
+    wonderful as the flowers of the snow. The observation is rare,
+    if not new, but I have seen in water slowly freezing six-rayed
+    ice-stars formed, and floating free on the surface. A six-rayed
+    star, moreover, is typical of the construction
+          <span class="pagenum"><a id="page354"></a>[pg 354]</span> of all our lake ice. It is
+       built up of such forms wonderfully interlaced.</p>
+
+    <p>Take a slab of lake ice and place it in the path of a
+    concentrated sunbeam. Watch the track of the beam through the
+    ice. Part of the beam is stopped, part of it goes through; the
+    former produces internal liquefaction, the latter has no effect
+    whatever upon the ice. But the liquefaction is not uniformly
+    diffused. From separate spots of the ice little shining points
+    are seen to sparkle forth. Every one of those points is
+    surrounded by a beautiful liquid flower with six petals.</p>
+
+    <p>Ice and water are so optically alike that unless the light
+    fall properly upon these flowers you cannot see them. But what
+    is the central spot? A vacuum. Ice swims on water because, bulk
+    for bulk, it is lighter than water; so that when ice is melted
+    it shrinks in size. Can the liquid flowers then occupy the
+    whole space of the ice melted? Plainly no. A little empty space
+    is formed with the flowers, and this space, or rather its
+    surface, shines in the sun with the lustre of burnished
+    silver.</p>
+
+    <p>In all cases the flowers are formed parallel to the surface
+    of freezing. They are formed when the sun shines upon the ice
+    of every lake; sometimes in myriads, and so small as to require
+    a magnifying glass to see them. They are always attainable, but
+    their beauty is often marred by internal defects of the ice.
+    Every one portion of the same piece of ice may show them
+    exquisitely, while a second portion shows them imperfectly.</p>
+
+    <p>Annexed is a very imperfect sketch of these beautiful
+    figures.</p><span class="pagenum"><a id="page355"></a>[pg 355]</span>
+
+    <p>Here we have a reversal of the process of crystallization.
+    The searching solar beam is delicate enough to take the
+    molecules down without deranging the order of their
+    architecture. Try the experiment for yourself with a
+    pocket-lens on a sunny day. You will not find the flowers
+    confused; they all lie parallel to the surface of freezing. In
+    this exquisite way every bit of the ice over which our skaters
+    glide in winter is put together.</p>
+
+    <p>I said that a portion of the sunbeam was stopped by the ice
+    and liquefied it. What is this portion? The dark heat of the
+    sun. The great body of the light waves and even a portion of
+    the dark ones, pass through the ice without losing any of their
+    heating power. When properly concentrated on combustible
+    bodies, even after having passed through the ice, their burning
+    power becomes manifest.</p>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/355.png"><img width="400"
+             src="images/355.png"
+             alt="LIQUID FLOWERS IN LAKE ICE."></a><br>
+        LIQUID FLOWERS IN LAKE ICE.
+    </div>
+
+    <p>And the ice itself may be employed to concentrate them. With
+    an ice-lens in the polar regions Dr. Scoresby has often
+    concentrated the sun's rays so as to make them burn wood, fire
+    gunpowder, and melt lead; thus proving that the heating power
+    is retained <span class="pagenum"><a id="page356"></a>[pg 356]</span> by the rays, even after
+       they have passed through so cold a substance.</p>
+
+    <p>By rendering the rays of the electric lamp parallel, and
+    then sending them through a lens of ice, we obtain all the
+    effects which Dr. Scoresby obtained with the rays of the
+    sun.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/356.png"><img width="500"
+             src="images/356.png"
+             alt="snowflakes"></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="page357"></a>[pg 357]</span>
+
+    <h2>THE ORGANIC WORLD</h2>
+
+    <h4>(<span class="sc">From The Elements of
+    Science.</span>)</h4>
+
+    <h3><span class="sc">By</span> ST. GEORGE MIVART F.R.S.</h3>
+    <hr class="short">
+
+    <div class="figleft"
+         style="width:100px;">
+        <a href="images/357.png"><img width="100"
+             src="images/357.png"
+             alt="T"></a>
+    </div>
+
+    <p>The number of all the various kinds of living creatures is
+    so enormous that it would be impossible to study them
+    profitably, were they not classified in an orderly manner.
+    Therefore the whole mass has been divided, in the first place,
+    into two supreme groups, fancifully termed kingdoms&mdash;the
+    "animal kingdom" and the "vegetal kingdom." Each of these is
+    subdivided into an orderly series of subordinate groups,
+    successively contained one within the other, and named
+    sub-kingdoms, classes, orders, families, genera and species.
+    The lowest group but one is the "genus," which contains one or
+    more different kinds termed "species," as e.g., the species
+    "wood anemone" and the species "blue titmouse." The lowest
+    group of all&mdash;a species&mdash;may be said to consist of
+    individuals which differ from each other only by trifling
+    characters, such as characters due to difference of sex, while
+    their peculiar organization is faithfully reproduced by
+    generation as a whole, though small individual differences
+    exist in all cases.</p>
+
+    <p>The vegetal, or vegetable, kingdom, consists of the great
+    mass of flowering plants, many of which, however, have such
+    inconspicuous flowers that they are <span class=
+    "pagenum"><a id="page358"></a>[pg 358]</span> mistakenly regarded as
+       flowerless, as is often the case with the grasses, the
+       pines, and the yews. Another mass, or sub-kingdom, of plants
+       consists of the really flowerless plants, such as the ferns,
+       horsetails (Fig. 1), lycopods, and mosses. Sea and
+       fresh-water weeds (<i>algæ</i>), and mushrooms, or "moulds,"
+       of all kinds (<i>fungi</i>), amongst which are the now
+       famous "bacteria," constitute a third and lowest set of
+       plants.</p>
+
+    <div class="figleft"
+         style="width:400px;">
+        <a href="images/358.png"><img width="400"
+             src="images/358.png"
+             alt=
+           "FIG. 1. HORSE-TAIL (Equisetum drummondii)."></a><br>
+        FIG. 1. HORSE-TAIL (<i>Equisetum drummondii</i>).
+    </div>
+
+    <p>The animal kingdom consists, first, of a sub-kingdom of
+    animals which possess a spinal column, or backbone, and which
+    are known as vertebrate animals. Such are all beasts, birds,
+    reptiles, and fishes. There are also a variety of remotely
+    allied marine organisms known as tunicates, sea-squirts, or
+    ascidians (Fig. 2). There is, further, an immense group of
+    arthropods, consisting of all insects, crab-like creatures,
+    hundred-legs and their allies, with spiders, scorpions, tics
+    and mites. We have also the sub-kingdom of shell-fish or
+    molluscs, <span class="pagenum"><a id="page359"></a>[pg 359]</span> including cuttle-fishes,
+       snails, whelks, limpets, the oyster, and a multitude of
+       allied forms. A multitudinous sub-kingdom of worms also
+       exists, as well as another of star-fishes and their
+       congeners. There is yet another of zoophytes, or polyps, and
+       another of sponges, and, finally, we have a sub-kingdom of
+       minute creatures, or animalculæ, of very varied forms, which
+       may make up the sub-kingdom of <i>Protozoa</i>, consisting
+       of animals which are mostly unicellular.</p>
+
+    <div class="figright"
+         style="width:175px;">
+        <a href="images/359.png"><img width="175"
+             src="images/359.png"
+             alt="FIG. 2. A TUNICATE (Ascidia)."></a><br>
+        FIG. 2. A TUNICATE (<i>Ascidia</i>).
+    </div>
+
+    <p>Multitudinous and varied as are the creatures which compose
+    this immense organic world, they nevertheless exhibit a very
+    remarkable uniformity of composition in their essential
+    structure. Every living creature from a man to a mushroom, or
+    even to the smallest animalcule or unicellular plant is always
+    partly fluid, but never entirely so. Every living creature also
+    consists in part (and that part is the most active living part)
+    of a soft, viscid, transparent, colorless substance, termed
+    protoplasm, which can be resolved into the four elements,
+    oxygen, hydrogen, nitrogen and carbon. Besides these four
+    elements, living organisms commonly contain sulphur,
+    phosphorus, chlorine, potassium, sodium, calcium, magnesium and
+    iron.</p>
+
+    <p>In the fact that living creatures always consist of the four
+    elements, oxygen, hydrogen, nitrogen and carbon, we have a
+    fundamental character whereby the organic and inorganic (or
+    non-living) worlds are to be <span class="pagenum"><a name=
+    "page360"
+       id="page360"></a>[pg 360]</span> distinguished, for as we
+       have seen, inorganic bodies, instead of being thus uniformly
+       constituted, may consist of the most diverse elements and
+       sometimes of but two or even of only one.</p>
+
+    <p>Again, many minerals, such as crystals, are bounded by plain
+    surfaces, and, with very few exceptions (spathic and hematite
+    iron and dolomite are such exceptions) none are bounded by
+    curved lines and surfaces, while living organisms are bounded
+    by such lines and surfaces.</p>
+
+    <p>Yet, again, if a crystal be cut through, its internal
+    structure will be seen to be similar throughout. But if the
+    body of any living creature be divided, it will, at the very
+    least, be seen to consist of a variety of minute distinct
+    particles, called "granules," variously distributed throughout
+    its interior.</p>
+
+    <p>All organisms consist either&mdash;as do the simplest,
+    mostly microscopic, plants and animals&mdash;of a single minute
+    mass of protoplasm, or of a few, or of many, or of an enormous
+    aggregation of such before-mentioned particles, each of which
+    is one of those bodies named a "cell" (Fig. 3). Cells may, or
+    may not, be enclosed in an investing coat or "cell-wall." Every
+    cell generally contains within it a denser, normally
+    spheroidal, body known as the nucleus.</p>
+
+    <p>Now protoplasm is a very unstable substance&mdash;as we have
+    seen many substances are whereof nitrogen is a component
+    part&mdash;and it possesses active properties which are not
+    present in the non-living, or inorganic world. In the latter,
+    differences of temperature will produce motion in the shape of
+    "currents," as we have seen with respect to masses of air and
+    water. But in a portion <span class="pagenum"><a id="page361"></a>[pg 361]</span> of protoplasm, an internal
+       circulation of currents in definite lines will establish
+       itself from other causes.</p>
+
+    <p>Inorganic bodies, as we have seen, will expand with heat, as
+    they may also do from imbibing moisture; but living protoplasm
+    has an apparently spontaneous power of contraction and
+    expansion under certain external conditions which do not
+    occasion such movements in inorganic matter.</p>
+
+    <div class="figright"
+         style="width:300px;">
+        <a href="images/361.png"><img width="300"
+             src="images/361.png"
+             alt="FIG. 3. CELL FROM A SALAMANDER."></a><br>
+        FIG. 3. CELL FROM A SALAMANDER.
+
+        <p><i>n</i>, nucleus; <i>n'</i>, nucleolus embedded in the
+        network of chromatin threads; <i>k</i>, network of the cell
+        external to the nucleus; <i>a</i>, attraction-sphere or
+        archoplasm containing minute bodies called centrosomes;
+        <i>cl</i>, membrane enclosing the cell externally,
+        <i>nl</i>, membrane surrounding the nucleus; <i>c</i>,
+        centrosomes.</p>
+    </div>
+
+    <p>Under favoring conditions, protoplasm has a power of
+    performing chemical changes, which result in producing heat far
+    more gently and continuously than it is produced by the
+    combustion of inorganic bodies. Thus it is that the heat is
+    produced which makes its presence evident to us in what we call
+    "warm-blooded animals," the most warm-blooded of all being
+    birds.</p>
+
+    <p>Protoplasm has also the wonderful power of transforming
+    certain adjacent substances into material like
+    itself&mdash;into its own substance&mdash;and so, in a sense,
+    creating a new material. Thus it is that organisms have the
+    power to nourish themselves and grow. An animal would vainly
+    swallow the most nourishing food if the ultimate, protoplasmic
+    particles of its body had not this power of "transforming"
+    suitable <span class="pagenum"><a id="page362"></a>[pg 362]</span> substances brought near
+       them in ways to be hereinafter noticed.</p>
+
+    <p>Without that, no organism could ever "grow." The growth of
+    organisms is utterly different from the increase in size of
+    inorganic bodies. Crystals, as we have seen, grow merely by
+    external increment; but organisms grow by an increment which
+    takes place in the very innermost substance of the tissues
+    which compose their bodies, and the innermost substance of the
+    cells which compose such tissues; this peculiar form of growth
+    is termed <i>intussusception</i>.</p>
+
+    <p>Protoplasm, after thus augmenting its mass, has a further
+    power of spontaneous division, whereby the mass of the entire
+    organism whereof such protoplasm forms a part, is augmented and
+    so growth is brought about.</p>
+
+    <p>The small particles of protoplasm which constitute "cells"
+    are far indeed from being structureless. Besides the nucleus
+    already mentioned there is a delicate network of threads of a
+    substance called <i>chromatin</i> within it, and another
+    network permeating the fluid of the cell substance, which
+    invest the nucleus often with further complications. These
+    networks generally perform (or undergo) a most complex series
+    of changes every time a cell spontaneously divides. In certain
+    cases, however, it appears that the nucleus divides into two in
+    a more simple fashion, the rest of the cell contents
+    subsequently dividing&mdash;each half enclosing one part of the
+    previously divided nucleus. It is by a continued process of
+    cell division that the complex structures of the most complex
+    organisms is brought about.</p>
+
+    <p>The division of a cell, or particle of protoplasm, is
+    <span class="pagenum"><a id="page363"></a>[pg 363]</span> indeed a necessary
+       consequence of its complete nutrition.</p>
+
+    <p>For new material can only be absorbed by its surface. But as
+    the cell grows, the proportion borne by its surface to its
+    mass, continually decreases; therefore this surface must soon
+    be too small to take in nourishment enough, and the particle,
+    or cell, must therefore either die or divide. By dividing, its
+    parts can continue the nutritive process till their surface, in
+    turn, becomes insufficient, when they must divide again, and so
+    on. Thus the term "feeding" has two senses. "To feed a horse,"
+    ordinarily means to give it a certain quantity of hay, oats or
+    what not; and such indeed is one kind of feeding. But
+    obviously, if the nourishment so taken could not get from the
+    stomach and intestines into the ultimate particles and cells of
+    the horse's body, the horse could not be nourished, and still
+    less could it grow. It is this latter process, called
+    assimilation, which is the real and essential process of
+    feeding, to which the process ordinarily so called is but
+    introductory.</p>
+
+    <p>Protoplasm has also the power of forming and ejecting from
+    its own substance, other substances which it has made, but
+    which are of a different nature to its own. This function, as
+    before said, is termed secretion; and we know the liver
+    secretes bile, and that the cow's udder secretes milk.</p>
+
+    <p>Here again we have an external and an internal process. The
+    milk is drawn forth from a receptacle, the udder, into which it
+    finds its way, and so, in a superficial sense, it may be called
+    an organ of secretion. Nevertheless the true internal secretion
+    takes place in <span class="pagenum"><a id="page364"></a>[pg 364]</span> the innermost substance of
+       the cells or particles of protoplasm, of the milk-land,
+       which particles really form that liquid.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/364.png"><img width="300"
+             src="images/364.png"
+             alt=
+           "FIG. 4. AMOEBA SHOWN IN TWO OF THE MANY IRREGULAR SHAPES IT ASSUMES."></a>
+
+        <p>FIG. 4. AMOEBA SHOWN IN TWO OF THE MANY IRREGULAR SHAPES
+        IT ASSUMES. <i>(After Howes</i>.)</p>
+
+        <p>The clear space within it is a contractile vesicle. The
+        dark body is the nucleus. In the right-hand figure there is
+        shown a particle of food, passing through the external
+        surface.</p>
+    </div>
+
+    <p>But every living creature consists at first entirely of a
+    particle of protoplasm. Therefore every other kind of substance
+    which may be found in every kind of plant or animal, must have
+    been formed through it, and be, in fact, a secretion from
+    protoplasm. Such is the rosy cheek of an apple, or of a maiden,
+    the luscious juice of the peach, the produce of the castor-oil
+    plant, the baleen that lines the whale's enormous jaws, as well
+    as that softest product, the fur of the chinchilla. Indeed,
+    every particle of protoplasm requires, in order that it may
+    live, a continuous process of exchange. It needs to be
+    continuously first built up by food, and then broken down by
+    discharging what is no longer needful for its healthy
+    existence. Thus the life of every organism is a life of almost
+    incessant change, not only in its being as a whole, but in that
+    of all its protoplasmic particles also.</p>
+
+    <p>Prominent among such processes is that of an interchange of
+    gases between the living being and its environment. This
+    process consists in an absorption of oxygen and a giving-out of
+    carbonic acid, which exchange is termed
+    respiration.</p><span class="pagenum"><a id="page365"></a>[pg 365]</span>
+
+    <p>Lastly, protoplasm has a power of motion when appropriately
+    acted on. It will then contract or expand its shape by
+    alternate protrusions and retractions of parts of its
+    substance. These movements are termed amoebiform, because they
+    quite resemble the movements of a small animalcule which is
+    named amoeba. (See Fig. 4.)</p>
+
+    <p>Such is the ultimate structure, and such are the fundamental
+    activities or functions of living organisms, as far as they can
+    here be described, from the lowest animalcule and unicellular
+    plant, up to the most complex organisms and the body of man
+    himself.</p>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/365.png"><img width="400"
+             src="images/365.png"
+             alt="cliffs"></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="page366"></a>[pg 366]</span>
+
+    <h2>INHABITANTS OF MY POOL</h2>
+
+    <h4>(<span class="sc">From Magic Glasses.</span>)</h4>
+
+    <h3><span class="sc">By</span> ARABELLA B. BUCKLEY.</h3>
+    <hr class="short">
+
+    <div class="figleft"
+         style="width:100px;">
+        <a href="images/366.png"><img width="100"
+             src="images/366.png"
+             alt="cliffs"></a>
+    </div>
+
+    <p>The pool lies in a deep hollow among a group of rocks and
+    boulders, close to the entrance of the cove, which can only be
+    entered at low water; it does not measure more than two feet
+    across, so that you can step over it, if you take care not to
+    slip on the masses of green and brown seaweed growing over the
+    rocks on its sides, as I have done many a time when collecting
+    specimens for our salt-water aquarium. I find now the only way
+    is to lie flat down on the rock, so that my hands and eyes are
+    free to observe and handle, and then, bringing my eye down to
+    the edge of the pool, to lift the seaweeds and let the sunlight
+    enter into the chinks and crannies. In this way I can catch
+    sight of many a small being either on the seaweed or the rocky
+    ledges, and even creatures transparent as glass become visible
+    by the thin outline gleaming in the sunlight. Then I pluck a
+    piece of seaweed, or chip off a fragment of rock with a
+    sharp-edged collecting knife, bringing away the specimen
+    uninjured upon it, and place it carefully in its own separate
+    bottle to be carried home alive and well.</p>
+
+    <p>Now though this little pool and I are old friends, I
+    <span class="pagenum"><a id="page367"></a>[pg 367]</span> find new treasures in it
+       almost every time I go, for it is almost as full of living
+       things as the heavens are of stars, and the tide as it comes
+       and goes brings many a mother there to find a safe home for
+       her little ones, and many a waif and stray to seek shelter
+       from the troublous life of the open ocean.</p>
+
+    <p>You will perhaps find it difficult to believe that in this
+    rock-bound basin there can be millions of living creatures
+    hidden away among the fine feathery weeds; yet so it is. Not
+    that they are always the same. At one time it may be the home
+    of myriads of infant crabs, not an eighth of an inch long,
+    another of baby sea-urchins only visible to the naked eye as
+    minute spots in the water, at another of young jelly-fish
+    growing on their tiny stalks, and splitting off one by one as
+    transparent bells to float away with the rising tide. Or it may
+    be that the whelk has chosen this quiet nook to deposit her
+    leathery eggs; or young barnacles, periwinkles, and limpets are
+    growing up among the green and brown tangles, while the
+    far-sailing velella and the stay-at-home sea-squirts, together
+    with a variety of other sea-animals, find a nursery and shelter
+    in their youth in this quiet harbor of rest.</p>
+
+    <p>And besides these casual visitors there are numberless
+    creatures which have lived and multiplied there, ever since I
+    first visited the pool. Tender red, olive-colored, and green
+    seaweeds, stony corallines, and acorn-barnacles lining the
+    floor, sea-anemones clinging to the sides, sponges tiny and
+    many-colored hiding under the ledges, and limpets and mussels
+    wedged in the cracks. These can be easily seen with the naked
+    eye, but they are not the most numerous inhabitants; for these
+    <span class="pagenum"><a id="page368"></a>[pg 368]</span> we must search with a
+       magnifying glass, which will reveal to us wonderful
+       fairy-forms, delicate crystal vases with tiny creatures in
+       them whose transparent lashes make whirlpools in the water,
+       living crystal bells so tiny that whole branches of them
+       look only like a fringe of hair, jelly globes rising and
+       falling in the water, patches of living jelly clinging to
+       the rocky sides of the pool, and a hundred other forms, some
+       so minute that you must examine the fine sand in which they
+       lie under a powerful microscope before you can even guess
+       that they are there.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/368.png"><img width="500"
+             src="images/368.png"
+             alt="FIG. 1. GROUP OF SEAWEEDS."></a><br>
+        FIG. 1. GROUP OF SEAWEEDS.<br>
+        (Natural size.)<br>
+        1, <i>Ulva Linza.</i> 2, <i>Sphacelaria filicina.</i> 3,
+        <i>Polysiphonia urceolata.</i> 4, <i>Corallina
+        officinalis.</i>
+    </div>
+
+    <p>So it has proved a rich hunting-ground, where summer and
+    winter, spring and autumn, I find some form to put under my
+    magic glass. There I can watch it for weeks growing and
+    multiplying under my care; moved only from the aquarium, where
+    I keep it supplied with healthy sea-water, to the tiny
+    <span class="pagenum"><a id="page369"></a>[pg 369]</span> transparent trough in which
+       I place it for a few hours to see the changes it has
+       undergone. I could tell you endless tales of transformations
+       in these tiny lives, but I want to-day to show you a few of
+       my friends, most of which I brought yesterday fresh from the
+       pool, and have prepared for you to examine.</p>
+
+    <div class="figright"
+         style="width:300px;">
+        <a href="images/369.png"><img width="300"
+             src="images/369.png"
+             alt="FIG. 2. Ulva lactuca, A GREEN-SEAWEED,"></a>
+
+        <p>FIG. 2. <i>Ulva lactuca</i>, A GREEN-SEAWEED, GREATLY
+        MAGNIFIED TO SHOW STRUCTURE. (<i>After Orested).</i></p>
+
+        <p>s, Spores in the cells, <i>ss</i>, Spores swimming out.
+        <i>h</i>, Holes through which spores have escaped.</p>
+    </div>
+
+    <p>Let us begin with seaweeds. I have said that there are three
+    leading colors in my pool&mdash;green, olive, and red&mdash;and
+    these tints mark roughly three kinds of weed, though they occur
+    in an endless variety of shapes. Here is a piece of the
+    beautiful pale green seaweed, called the Laver or Sea-Lettuce,
+    <i>Ulva Linza</i> (1, Fig. 1),<a id="footnotetag4"></a><a href="#footnote4"><sup>4</sup></a> which grows in long ribbons in
+       a sunny nook in the water. I have placed under the first
+       microscope a piece of this weed which is just sending out
+       young seaweeds in the shape of tiny cells, with lashes very
+       like those we saw coming from the moss-flower, and I have
+       pressed them in the position in which they would naturally
+       leave the plant. You will also see on this side several
+       cells in which these tiny spores are forming, ready to burst
+       out and swim; for this green weed is merely a collection of
+       cells, like the single-celled plants on land. Each cell
+       <span class="pagenum"><a id="page370"></a>[pg 370]</span> can work as a separate
+       plant; it feeds, grows, and can send out its own young
+       spores.</p>
+
+    <p>This deep olive-green feathery weed (2, Fig. 1), of which a
+    piece is magnified under the next microscope (2, Fig. 3), is
+    very different. It is a higher plant, and works harder for its
+    living, using the darker rays of sunlight which penetrate into
+    shady parts of the pool. So it comes to pass that its cells
+    divide the work. Those of the feathery threads make the food,
+    while others, growing on short stalks on the shafts of the
+    feather, make and send out the young spores.</p>
+
+    <p>Lastly, the lovely red threadlike weeds, such as this
+    <i>Polysiphonia urceolata</i> (3, Fig. 1), carry actual urns on
+    their stems like those of mosses. In fact, the history of these
+    urns (see 3, Fig. 3), is much the same in the two classes of
+    plants, only that instead of the urn being pushed up on a thin
+    stalk as in the moss, it remains on the seaweed close down to
+    the stem, when it grows out of the plant-egg, and the tiny
+    plant is shut in till the spores are ready to swim out.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/370.png"><img width="300"
+             src="images/370.png"
+             alt=
+           "FIG. 3. THREE SEAWEEDS OF FIG. 1 MUCH MAGNIFIED TO SHOW FRUITS."></a>
+
+        <p>FIG. 3. THREE SEAWEEDS OF FIG. 1 MUCH MAGNIFIED TO SHOW
+        FRUITS. (<i>Harvey.</i>)</p>
+
+        <p>2, <i>Sphacelaria filicina.</i> 3, <i>Polysiphonia
+        urceolata.</i> 4, <i>Corallina officinalis.</i></p>
+    </div>
+
+    <p>The stony corallines (4, Figs. 1 and 3), which build so much
+    carbonate of lime into their stems, are near relations of the
+    red seaweeds. There are plenty of them in my pool. Some of
+    them, of a deep purple color, grow upright in stiff groups
+    about three or four <span class="pagenum"><a id="page371"></a>[pg 371]</span> inches high; and others,
+       which form crusts over the stones and weeds, are a pale rose
+       color; but both kinds, when the plant dies, leaving the
+       stony skeleton (1, Fig. 4), are a pure white, and used to be
+       mistaken for corals. They belong to the same order of plants
+       as the red weeds, which all live in shady nooks in the
+       pools, and are the highest of their race.</p>
+
+    <div class="figright"
+         style="width:400px;">
+        <a href="images/371.png"><img width="400"
+             src="images/371.png"
+             alt=
+           "FIG. 4. CORALLINE AND SERTULARIA, TO SHOW LIKENESS BETWEEN THE ANIMAL SERTULARIA AND THE PLANT CORALLINE."></a>
+
+        <p>FIG. 4. CORALLINE AND SERTULARIA, TO SHOW LIKENESS
+        BETWEEN THE ANIMAL SERTULARIA AND THE PLANT
+        CORALLINE.</p>1, <i>Corallina officinalis.</i> 2,
+        <i>Sertularia filicula.</i>
+    </div>
+
+    <p>My pool is full of different forms of these four weeds. The
+    green ribbons float on the surface rooted to the sides of the
+    pool, and, as the sun shines upon it, the glittering bubbles
+    rising from them show that they are working up food out of the
+    air in the water, and giving off oxygen. The brown weeds lie
+    chiefly under the shelves of rocks, for they can manage with
+    less sunlight, and use the darker rays which pass by the green
+    weeds; and last of all, the red weeds and corallines, small and
+    delicate in form, line the bottom of the pool in its darkest
+    nooks.</p>
+
+    <p>And now if I hand round two specimens,&mdash;one a
+    coralline, and the other something you do not yet know,&mdash;I
+    am sure you will say at first sight that they belong to the
+    same family, and, in fact, if you buy at the seaside a group of
+    seaweeds gummed on paper, you will most likely get both these
+    among them. Yet the truth is; that while the coralline (1, Fig.
+    4) is a plant, <span class="pagenum"><a id="page372"></a>[pg 372]</span> the other specimen (2),
+       which is called <i>Sertularia filicula</i>, is an
+       animal.</p>
+
+    <p>This special sertularian grows up right in my pool on stones
+    or often on seaweeds, but I have here (Fig. 5) another and much
+    smaller one which lives literally in millions hanging its cups
+    downwards. I find it not only under the narrow ledges of the
+    pool sheltered by the seaweed, but forming a fringe along all
+    the rocks on each side of the cove near to low-water mark, and
+    for a long time I passed it by thinking it was of no interest.
+    But I have long since given up thinking this of anything,
+    especially in my pool, for my magic glass has taught me that
+    there is not even a living speck which does not open out into
+    something marvellous and beautiful. So I chipped off a small
+    piece of rock and brought the fringe home, and found, when I
+    hung it up in clear sea-water as I have done over this glass
+    trough (Fig. 5) and looked at it through the lens, that each
+    thread of the dense fringe, in itself not a quarter of an inch
+    deep, turns out to be a tiny sertularian with at least twenty
+    mouths. You can see this with your pocket lens even as it hangs
+    here, and when you have examined it you can by and by take off
+    one thread and put it carefully in the trough. I promise you a
+    sight of the most beautiful little beings which exist in
+    nature.</p>
+
+    <div class="figleft"
+         style="width:350px;">
+        <a href="images/372.png"><img width="350"
+             src="images/372.png"
+             alt=
+           "FIG. 5. Sertularia tenella, HANGING FROM A SPLINT OF ROCK OVER A WATER TROUGH."></a>
+
+        <p>FIG. 5. <i>Sertularia tenella</i>, HANGING FROM A SPLINT
+        OF ROCK OVER A WATER TROUGH. ALSO PIECE ENLARGED TO SHOW
+        THE ANIMAL ROTRUDING.</p>
+    </div>
+
+    <p>Come and look at it. It is a horny-branched stem
+          <span class="pagenum"><a id="page373"></a>[pg 373]</span> with a double row of tiny
+       cups all along each side. Out of these cups there appear a
+       row of tiny cups all along each side (see Fig. 5), Out of
+       these cups there appear from time to time sixteen minute
+       transparent tentacles as fine as spun glass, which wave
+       about in the water. If you shake the glass a little, in an
+       instant each crystal star vanishes into its cup, to come out
+       again a few minutes later; so that now here, now there, the
+       delicate animal-flowers spread out on each side of the stem,
+       and the tree is covered with moving beings. These tentacles
+       are feelers, which lash food into a mouth and stomach in
+       each cup, where it is digested and passed, through a hole in
+       the bottom, along a jelly thread which runs down the stem
+       and joins all the mouths together. In this way the food is
+       distributed all over the tree, which is, in fact, one animal
+       with many feeding-cups. Some day I will show you one of
+       these cups with the tentacles stretched out and mounted on a
+       slide, so that you can examine a tentacle with a very strong
+       magnifying power. You will then see that it is dotted over
+       with cells, in which are coiled fine threads. The animal
+       uses these threads to paralyze the creatures on which it
+       feeds, for at the base of each thread there is a poison
+       gland.</p>
+
+    <p>In the larger Sertularia the whole branched tree is
+    connected by jelly threads, running through the stem, and all
+    the thousands of mouths are spread out in the water. One large
+    form called <i>Sertularia cupressina</i> grows sometimes three
+    feet high and bears as many as a hundred thousand cups, with
+    living mouths, on its branches.</p>
+
+    <p>The next of my minute friends I can only show to
+          <span class="pagenum"><a id="page374"></a>[pg 374]</span> the class in a diagram, but
+       you will see it under the fourth microscope by and by. I had
+       great trouble in finding it yesterday, though I know its
+       haunts upon the green weed, for it is so minute and
+       transparent that even when the weed is in a trough a
+       magnifying-glass will scarcely detect it. And I must warn
+       you that if you want to know any of the minute creatures we
+       are studying, you must visit one place constantly. You may
+       in a casual way find many of them on seaweed, or in the damp
+       ooze and mud, but it will be by chance only; to look for
+       them with any certainty you must take trouble in making
+       their acquaintance.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/374.png"><img width="300"
+             src="images/374.png"
+             alt=
+           "FIG. 6. Thuricolla folliculata and Chilomonas amygdalum."></a>
+
+        <p>FIG. 6. <i>Thuricolla folliculata</i> and <i>Chilomonas
+        amygdalum</i>. (<i>Saville Kent</i>.)</p>
+
+        <p>1, <i>Thuricolla</i> erect. 2, Retracted. 3, Dividing.
+        4, <i>Chilomonas amygdalum. hc,</i> Horny carapace,
+        <i>cv</i>, Contractile vesicle. <i>v</i> Closing
+        valves.</p>
+    </div>
+
+    <p>Turning then to the diagram (Fig. 6) I will describe it as I
+    hope you will see it under the microscope&mdash;a curious,
+    tiny, perfectly transparent open-mouthed vase standing upright
+    on the weed, and having an equally transparent being rising up
+    in it and waving its tiny lashes in the water. This is really
+    all one animal, the vase <i>hc</i> being the horny covering or
+    carapace of the body, which last stands up like a tube in the
+    centre. If you watch carefully, you may even see the minute
+    atoms of food twisting round inside the tube until they are
+    digested, after they have been swept in at the wide open mouth
+    by the whirling lashes. You will see this <span class=
+    "pagenum"><a id="page375"></a>[pg 375]</span> more clearly if you put a
+       little rice-flour, very minutely powdered and colored by
+       carmine, into the water; for you can trace these red atoms
+       into some round spaces called <i>vacuoles</i> which are
+       dotted over the body of the animal, and are really globules
+       of watery fluid in which the food is probably partly
+       digested.</p>
+
+    <p>You will notice, however, one round clear space <i>(cv)</i>
+    into which they do not go, and after a time you will be able to
+    observe that this round spot closes up or contracts very
+    quickly, and then expands again very slowly. As it expands it
+    fills with a clear fluid, and naturalists have not yet decided
+    exactly what work it does. It may serve the animal either for
+    breathing, or as a very simple heart, making the fluids
+    circulate in the tube. The next interesting point about this
+    little being is the way it retreats into its sheltering vase.
+    Even while you are watching, it is quite likely it may all at
+    once draw itself down to the bottom as in No. 2, and folding
+    down the valves <i>w</i> of horny teeth which grow on each
+    side, shut itself in from some fancied danger. Another very
+    curious point is that, besides sending forth young ones, these
+    creatures multiply by dividing in two (see No. 3, Fig. 6), each
+    one closing its own part of the vase into a new home.</p>
+
+    <p>There are hundreds of these Infusoria, as they are called,
+    in my pond, some with vases, some without, some fixed to weeds
+    and stones, others swimming about freely. Even in the
+    water-trough in which this Thuricolla stands, I saw several
+    smaller forms, and the next microscope has a trough filled with
+    the minutest form of all, called a Monad. These are so small
+    that two thousand of them could lie side by side in an inch;
+    <span class="pagenum"><a id="page376"></a>[pg 376]</span> that is, if you could make
+       them lie at all, for they are the most restless little
+       beings, darting hither and thither, scarcely even halting
+       except to turn back. And yet though there are so many of
+       them, and as far as we know they have no organs of sight,
+       they never run up against each other, but glide past more
+       cleverly than any clear-sighted fish. These creatures are
+       mostly to be found among decaying seaweed, and though they
+       are so tiny, you can still see distinctly the clear space
+       contracting and expanding within them.</p>
+
+    <div class="figleft"
+         style="width:350px;">
+        <a href="images/376.png"><img width="350"
+             src="images/376.png"
+             alt="FIG. 7. LIVING DIATOMS."></a><br>
+        FIG. 7. LIVING DIATOMS.
+
+        <p><i>a, Cocconema lanceolatum. b, Bacillaria paradoxa. c,
+        Gomphonema marinum. d, Diatoma hyalina</i>.</p>
+    </div>
+
+    <p>But if there are so many thousands of mouths to feed, on the
+    tree-like Sertulariæ as well as in all these Infusoria, where
+    does the food come from? Partly from the numerous atoms of
+    decaying life all around, and the minute eggs of animals and
+    spores of plants; but besides these, the pool is full of minute
+    living plants&mdash;small jelly masses with solid coats of
+    flint which are moulded into most lovely shapes. Plants formed
+    of jelly and flint! You will think I am joking, but I am not.
+    These plants, called Diatoms, which live both in salt and fresh
+    water, are single cells feeding and growing just like those we
+    took from the water-butt, only that instead of a soft covering
+    they build up <span class="pagenum"><a id="page377"></a>[pg 377]</span> a flinty skeleton. They are
+       so small, that many of them must be magnified to fifty times
+       their real size before you can even see them distinctly. Yet
+       the skeletons of these almost invisible plants are carved
+       and chiselled in the most delicate patterns. I showed you a
+       group of these in our lecture on magic glasses, and now I
+       have brought a few living ones that we may learn to know
+       them. The diagram (Fig. 7) shows the chief forms you will
+       see on the different slides.</p>
+
+    <p>The first one, <i>Sacillaria paradoxa</i> (<i>b</i>, Fig.
+    7), looks like a number of rods clinging one to another in a
+    string, but each one of these is a single-celled plant with a
+    jelly cell surrounding the flinty skeleton. You will see that
+    they move to and fro over each other in the water.</p>
+
+    <p>The next two forms, <i>a</i> and <i>c</i>, look much more
+    like plants, for the cells arrange themselves on a jelly stem,
+    which by and by disappears, leaving only the separate flint
+    skeletons. The last form, <i>d</i>, is something midway between
+    the other forms, the separate cells hang on to each other and
+    also on to a straight jelly stem.</p>
+
+    <div class="figright"
+         style="width:175px;">
+        <a href="images/377.png"><img width="175"
+             src="images/377.png"
+             alt="FIG. 8. A DIATOM"></a>
+
+        <p>FIG. 8. A DIATOM (<i>Diatoma vulgare</i>) GROWING.</p>
+
+        <p><i>a, b,</i> Flint skeleton inside the jelly-cell. <i>a,
+        c</i> and <i>d, b</i>, Two flint skeletons formed by new
+        valves, <i>c</i> and <i>d</i>, forming within the first
+        skeleton.</p>
+    </div>
+
+    <p>Another species of Diatoma (Fig. 8) called <i>Diatoma
+    vulgare</i>, is a very simple and common form, and will help to
+    explain how these plants grow. The two flinty valves <i>a,
+    b</i> inside the cell are not quite the same size; the older
+    one <i>a</i> is larger than the younger one <i>b</i> and fits
+    over it like the cover of a pill-box. As the plant grows, the
+    cell enlarges and forms two <span class="pagenum"><a name=
+    "page378"
+       id="page378"></a>[pg 378]</span> more valves, one <i>c</i>
+       fitting into the cover <i>a</i>, so as to make a complete
+       box <i>ac</i>, and a second, <i>d</i>, back to back with
+       <i>c</i>, fitting into the valve <i>b</i>, and making
+       another complete <i>bd</i>. This goes on very rapidly, and
+       in this plant each new cell separates as it is formed, and
+       the free diatoms move about quite actively in the water.</p>
+
+    <p>If you consider for a moment, you will see that, as the new
+    valves always fit into the old ones, each must be smaller than
+    the last, and so there comes a time when the valves have become
+    too small to go on increasing. Then the plant must begin
+    afresh. So the two halves of the last cell open, and throwing
+    out their flinty skeletons, cover themselves with a thin jelly
+    layer, and form a new cell which grows larger than any of the
+    old ones. These, which are spore-cells, then form flinty valves
+    inside, and the whole thing begins again.</p>
+
+    <p>Now, though the plants themselves die, or become the food of
+    minute animals, the flinty skeletons are not destroyed, but go
+    on accumulating in the waters of the ponds, lakes, rivers, and
+    seas, all over the world. Untold millions have no doubt
+    crumbled to dust and gone back into the waters, but untold
+    millions also have survived. The towns of Berlin in Europe and
+    of Richmond in the United States are actually built upon ground
+    called "infusorial earth," composed almost entirely of valves
+    of these minute diatoms which have accumulated to a thickness
+    of more than eighty feet! Those under Berlin are fresh-water
+    forms, and must have lived in a lake, while those of Richmond
+    belong to salt-water forms. Every inch of the ground under
+    those cities represents thousands and thousands of living
+    plants <span class="pagenum"><a id="page379"></a>[pg 379]</span> which flourished in ages
+       long gone by, and were no larger than those you will see
+       presently under the microscope.</p>
+
+    <p>These are a very few of the microscopic inhabitants of my
+    pond, but, as you will confuse them if I show you too many, we
+    will conclude with two rather larger specimens, and examine
+    them carefully. The first, called the Cydippe, is a lovely,
+    transparent living ball, which I want to explain to you because
+    it is so wondrously beautiful. The second, the Sea-mat or
+    Flustra, looks like a crumpled drab-colored seaweed, but is
+    really composed of many thousands of grottos, the homes of tiny
+    sea-animals.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/379.jpg"><img width="500"
+             src="images/379.jpg"
+             alt="FIG. 9. Cydippe Pileus."></a><br>
+        FIG. 9. <i>Cydippe Pileus</i>.
+
+        <p>1, Animal with tentacles <i>t</i>, bearing small
+        tendrils <i>t'</i>. 2, Body of animal enlarged. <i>m</i>,
+        Mouth. <i>c</i>, Digestive cavity. <i>s</i>, Sac into which
+        the tentacles are withdrawn. <i>p</i>, Bands with comb-like
+        plates. 3, Portion of a band enlarged to show the moving
+        plates <i>p</i>.</p>
+    </div>
+
+    <p>Let us take the Cydippe first (1, Fig. 9). I have six here,
+    each in a separate tumbler, and could have brought many more,
+    for when I dipped my net in the pool yesterday such numbers
+    were caught in it that I believe the retreating tide must just
+    have left a shoal behind. Put a tumbler on the desk in front of
+    you, <span class="pagenum"><a id="page380"></a>[pg 380]</span> and if the light falls well
+       upon it you will see a transparent ball about the size of a
+       large pea marked with eight bright bands, which begin at the
+       lower end of the ball and reach nearly to the top, dividing
+       the outside into sections like the ribs of a melon. The
+       creature is so perfectly transparent that you can count all
+       the eight bands.</p>
+
+    <p>At the top of the ball is a slight bulge which is the mouth
+    (<i>m</i> 2, Fig. 9), and from it, inside the ball hangs a long
+    bag or stomach, which opens below into a cavity, from which two
+    canals branch out, one on each side, and these divide again
+    into four canals which go one into each of the tubes running
+    down the bands. From this cavity the food, which is digested in
+    the stomach, is carried by the canals all over the body. The
+    smaller tubes which branch out of these canals cannot be seen
+    clearly without a very strong lens, and the only other parts
+    you can discern in this transparent ball are two long sacs on
+    each side of the lower end. These are the tentacle sacs, in
+    which are coiled up the tentacles, which we shall describe
+    presently. Lastly you can notice that the bands outside the
+    globe are broader in the middle than at the ends, and are
+    striped across by a number of ridges.</p>
+
+    <p>In moving the tumblers the water has naturally been shaken,
+    and the creature being alarmed will probably at first remain
+    motionless. But very soon it will begin to play in the water,
+    rising and falling, and swimming gracefully from side to side.
+    Now you will notice a curious effect, for the bands will
+    glitter and become tinged with prismatic colors, till, as it
+    moves more and more rapidly these colors, reflected in the
+    jelly, seem <span class="pagenum"><a id="page381"></a>[pg 381]</span> to tinge the whole ball
+       with colors like those on a soap-bubble, while from the two
+       sacs below come forth two long transparent threads like spun
+       glass. At first these appear to be simple threads, but as
+       they gradually open out to about four or five inches,
+       smaller threads uncoil on each side of the line till there
+       are about fifty on each line. These short tendrils are never
+       still for long; as the main threads wave to and fro, some of
+       the shorter ones coil up and hang like tiny beads, then
+       these uncoil and others roll up, so that these graceful
+       floating lines are never two seconds alike.</p>
+
+    <p>We do not really know their use. Sometimes the creature
+    anchors itself by them, rising and falling as they stretch out
+    or coil up; but more often they float idly behind it in the
+    water. At first you would perhaps think that they served to
+    drive the ball through the water, but this is done by a special
+    apparatus. The cross ridges which we noticed on the bands are
+    really flat comb-like plates (<i>p</i>, Fig. 9), of which there
+    are about twenty or thirty on each band; and these vibrate very
+    rapidly, so that two hundred or more paddles drive the tiny
+    ball through the water. This is the cause of the prismatic
+    colors; for iridescent tints are produced by the play of light
+    upon the glittering plates, as they incessantly change their
+    angle. Sometimes they move all at once, sometimes only a few at
+    a time, and it is evident the creature controls them at
+    will.</p>
+
+    <p>This lovely fairy-like globe, with its long floating
+    tentacles and rainbow tints, was for a long time classed with
+    the jelly-fish; but it really is most nearly related to the
+    sea-anemones, as it has a true central cavity which acts as a
+    stomach, and many other points in common <span class=
+    "pagenum"><a id="page382"></a>[pg 382]</span> with the <i>Actinozoa</i>.
+       We cannot help wondering, as the little being glides hither
+       and thither, whether it can see where it is going. It has
+       nerves of a low kind which start from a little dark spot
+       (<i>ng</i>) exactly at the south pole of the ball, and at
+       that point a sense-organ of some kind exists, but what
+       impression the creature gains from it of the world outside
+       we cannot tell.</p>
+
+    <p>I am afraid you may think it dull to turn from such a
+    beautiful being as this, to the gray leaf which looks only like
+    a dead dry seaweed; yet you will be wrong, for a more wonderful
+    history attaches to this crumpled dead-looking leaf than to the
+    lovely jelly-globe.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/382.png"><img width="300"
+             src="images/382.png"
+             alt="FIG. 10. THE SEA-MAT OR FLUSTRA."></a>
+
+        <p>FIG. 10. THE SEA-MAT OR FLUSTRA (<i>Flustra
+        foliacea</i>).</p>
+
+        <p>1, Natural size. 2, Much magnified, <i>s</i>, Slit
+        caused by drawing in of the animal <i>a</i>.</p>
+    </div>
+
+    <p>First of all I will pass round pieces of the dry leaf (1,
+    Fig. 10), and while you are getting them I will tell you where
+    I found the living ones. Great masses of the Flustra, as it is
+    called, line the bottom and sides of my pool. They grow in
+    tufts, standing upright on the rock, and looking exactly like
+    hard gray seaweeds, while there is nothing to lead you to
+    suspect that they are anything else. Yesterday I chipped off
+    very carefully a piece of rock with a tuft upon it, and have
+    kept it since in a glass globe by itself with sea-water, for
+    the little creatures living in this marine city require a very
+    good supply of healthy water and air. I have called it a
+    "marine <span class="pagenum"><a id="page383"></a>[pg 383]</span> city," and now I will tell
+       you why. Take the piece in your hand and run your finger
+       gently up and down it; you will glide quite comfortably from
+       the lower to the higher part of the leaf, but when you come
+       back you will feel your finger catch slightly on a rough
+       surface. Your pocket lens will show you why this is, for if
+       you look through it at the surface of the leaf you will see
+       it is not smooth, but composed of hundreds of tiny alcoves
+       with arched tops; and on each side of these tops stand two
+       short blunt spines, making four in all, pointing upwards, so
+       as partly to cover the alcove above. As your finger went up
+       it glided over the spines, but on coming back it met their
+       points. This is all you can see in the dead specimen; I must
+       show you the rest by diagrams, and by and by under the
+       microscope.</p>
+
+    <p>First, then, in the living specimen which I have here, those
+    alcoves are not open as in the dead piece, but covered over
+    with a transparent skin, in which, near the top of the alcove
+    just where the curve begins, is a slit (<i>s</i> 2, Fig. 10)
+    Unfortunately, the membrane covering this alcove is too dense
+    for you to distinguish the parts within. Presently, however, if
+    you are watching a piece of this living leaf in a flat
+    water-cell under the microscope, you will see the slit slowly
+    open, and begin to turn as it were inside out, exactly like the
+    finger of a glove, which has been pushed in at the tip,
+    gradually rises up when you put your finger inside it. As this
+    goes on, a bundle of threads appears, at first closed like a
+    bud, but gradually opening out into a crown of tentacles, each
+    one clothed with hairs. Then you will see that the slit was not
+    exactly a slit after all, but the round edge where the sac was
+    <span class="pagenum"><a id="page384"></a>[pg 384]</span> pushed in. Ah! you will
+       say, you are now showing me a polyp like those on the
+       sertularian tree. Not so fast, my friend; you have not
+       studied what is still under the covering skin and hidden in
+       the living animal. I have, however, prepared a slide with
+       this membrane removed and there you can observe the
+       different parts, and learn that each one of these alcoves
+       contains a complete animal, and not merely one among many
+       mouths, like the polyp on Sertularia.</p>
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/384.jpg"><img width="250"
+             src="images/384.jpg"
+             alt=
+           "FIG. 11. DIAGRAM OF THE ANIMAL IN THE FLUSTRA OR SEA-MAT."></a>
+
+        <p>FIG. 11. DIAGRAM OF THE ANIMAL IN THE FLUSTRA OR
+        SEA-MAT.</p>
+
+        <p>1, Animal protruding. 2, Animal retracted in the sheath,
+        <i>sh</i>, Covering sheath, <i>s</i>, Slit. <i>t</i>,
+        Tentacles. <i>m</i>, Mouth. <i>th</i>, Throat, <i>st</i>,
+        Stomach. <i>i</i>, Intestine, <i>r</i>, Retractor muscle,
+        <i>e</i>, Egg-forming parts. <i>g</i>, Nerve-ganglion.</p>
+    </div>
+
+    <p>Each of these little beings (<i>a</i>, Fig. 10) living in
+    its alcove has a mouth, throat, stomach, intestine, muscles,
+    and nerves starting from the ganglion of nervous matter,
+    besides all that is necessary for producing eggs and sending
+    forth young ones. You can trace all these under the microscope
+    (see 2, Fig. 11) as the creature lies curiously doubled up in
+    its bed, with its body bent in a loop; the intestine <i>i</i>,
+    out of which the refuse food passes, coming back close up to
+    the slit. When it is at rest, the top of the sac in which it
+    lies is pulled in by the retractor muscle <i>r</i>, and looks,
+    as I have said, like the finger of a glove with the top pushed
+    in. When it wishes to feed this top is drawn out by muscles
+    running <span class="pagenum"><a id="page385"></a>[pg 385]</span> round the sac, and the
+       tentacles open and wave in the water (1, Fig. 11).</p>
+
+    <p>Look now at the alcoves, the homes of these animals; see how
+    tiny they are and how closely they fit together. Mr. Gosse, the
+    naturalist, has reckoned that there are six thousand, seven
+    hundred and twenty alcoves in a square inch; then if you turn
+    the leaf over you will see that there is another set, fixed
+    back to back with these, on the other side, making in all,
+    thirteen thousand, four hundred and forty alcoves. Now a
+    moderate-sized leaf of flustra measures about three square
+    inches, taking all the rounded lobes into account, so you will
+    see we get forty thousand, three hundred and twenty as a rough
+    estimate of the number of beings on this one leaf. But if you
+    look at this tuft I have brought, you will find it is composed
+    of twelve such leaves, and this after all is a very small part
+    of the mass growing round my pool. Was I wrong, then, when I
+    said my miniature ocean contains as many millions of beings as
+    there are stars in the heavens?</p>
+
+    <p>You will want to know how these leaves grew, and it is in
+    this way. First a little free swimming animal, a mere living
+    sac provided with lashes, settles down and grows into one
+    little horny alcove, with its live creature inside, which in
+    time sends off from it three to five buds, forming alcoves all
+    round the top and sides of the first one, growing on to it.
+    These again bud out, and you can thus easily understand that,
+    in this way, in time a good-sized leaf is formed. Meanwhile the
+    creatures also send forth new swimming cells, which settle down
+    near to begin new leaves, and thus <span class=
+    "pagenum"><a id="page386"></a>[pg 386]</span> a tuft is formed; and long
+       after the beings in earlier parts of the leaf have died and
+       left their alcoves empty, those round the margin are still
+       alive and spreading....</p>
+
+    <p>If you can trace the spore-cells and urns in the seaweeds,
+    observe the polyps in the Sertularia, and count the number of
+    mouths on a branch of my animal fringe (Sertularia tenella); if
+    you make acquaintance with the Thuricolla in its vase, and are
+    fortunate enough to see one divide in two; if you learn to know
+    some of the beautiful forms of diatoms, and can picture to
+    yourself the life of the tiny inhabitants of the Flustra; then
+    you will have used your microscope with some effect, and be
+    prepared for an expedition to my pool, where we will go
+    together some day to seek new treasures.</p>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/386.png"><img width="400"
+             src="images/386.png"
+             alt="page decoration"></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="page387"></a>[pg 387]</span>
+
+    <h2>NOTES</h2>
+
+    <p><span class="sc">Agassiz, J.L.R.</span>, naturalist, born in
+    Switzerland, 1807; died, Cambridge, Mass., 1873. In 1846 he
+    came to America, after having gained a high reputation in
+    Europe, to deliver a course of lectures in Boston "On the Plan
+    of the Creation," and met with such success that he spent the
+    rest of his days there, declining an invitation to return to
+    his native country and to Paris. In 1848 he was elected to the
+    chair of Natural History at Harvard. In 1850-51 he went on an
+    expedition to the Florida Reefs. In 1858 he founded and
+    organized the Museum of Comparative Zoölogy at
+    Cambridge&mdash;and, later on, went on his important voyage to
+    Brazil. In 1872 he founded and organized the summer school of
+    Natural History at Buzzard's Bay. He wrote "The Fishes of
+    Brazil," "A Study of Glaciers," "Natural History of the Fresh
+    Water Fishes of Central Europe," "Contributions to the Natural
+    History of the United States" (unfinished), and with his wife,
+    "A Journey in Brazil."</p>
+
+    <p><span class="sc">Ball, Prof. Sir R.S.</span>, English
+    astronomer, born in Dublin, 1840. Was appointed Lord Ross's
+    astronomer in 1865. Professor of mathematics and mechanics at
+    the Royal Irish College of Science in 1873, and is now
+    astronomer royal for Ireland. He is the author of "The Story of
+    the Heavens," "Starland," etc., and is well known as a
+    successful lecturer on astronomical subjects in this
+    country.</p>
+
+    <p><span class="sc">Darwin, Charles R.</span>, English
+    naturalist, born, 1809; died, 1882. He first formulated what is
+    known as the principle of Natural Selection. In 1831 he went in
+    the famous scientific voyage of the <i>Beagle</i> as
+    naturalist, and afterwards published an account of it. He was
+    one of the most thorough, careful, and painstaking scientific
+    men of this or any age. He is the author of many famous books.
+    "The Origin of Species," "The Descent of Man," "Insectivorous
+    Plants," "The Power of Movement in Plants," "The Structure and
+    Distribution of Coral Reefs," "Geological Observations on
+    Volcanic Islands." "The Formation of Vegetable Mould" was his
+    last published work.</p>
+
+    <p><span class="sc">Flammarion, C.</span>, famous French
+    astronomer, born, 1842. He has written many popular works on
+    astronomy, most of which have been translated into English.
+    "The Stars," "The World Before the Creation," "Uranus,"
+    "Comets," "Popular Astronomy," are among his best known.</p>
+
+    <p><span class="sc">Holden, Prof. E.S.</span>, American
+    astronomer, born at St. Louis, 1846. Lieutenant engineers,
+    U.S.A., 1870-73; professor mathematics, U.S.N., 1873-81;
+    director Washburn Observatory, 1881-85; president University of
+    California, 1883-88; director Lick Observatory, 1888-98. Is a
+    member of several learned societies of Europe. Is the author of
+    a "Life of William Herschel," "A Hand-book of the Lick
+    Observatory," "Earth and Sky," "Primer of Heraldry,"
+    "Elementary Astronomy," "Family of the Sun," "Essays in
+    Astronomy," "Stories of the Great Astronomers," etc.</p>
+
+    <p><span class="sc">Huxley, T.H.</span>, English biologist,
+    born, 1825; died, 1895. Went on an exploring expedition on the
+    <i>Rattlesnake</i>, and devoted himself to the study of marine
+    life. For his scientific researches he received many honors.
+    His lectures were models of clearness, and he could simplify
+    the most difficult subjects. He strongly advocated Darwin's
+    views and evolutionist doctrines. His writings are numerous and
+    many of them technical. Among some of the most popular are
+    "Man's Place in Nature," his "Lay Sermons," "Critiques and
+    Addresses," "American Addresses," "Physiography," "Science and
+    Culture," "Lessons in Elementary Physiology,"
+    etc.</p><span class="pagenum"><a id="page388"></a>[pg 388]</span>
+
+    <p><span class="sc">Kingsley, C.</span>, English clergyman and
+    author, born, 1819; died, 1875. Wrote "Westward, Ho!" which
+    every boy should read, "Hypatia," "Alton Locke," "Hereward the
+    Wake," etc., and a charming book of travel, entitled, "At
+    Last." His "Water Babies" is exceedingly popular, and his
+    "Heroes" is a book much appreciated by the boys and girls
+    alike.</p>
+
+    <p><span class="sc">Proctor, R.A.</span>, English astronomer,
+    born, 1834; died, 1888. He was a very popular writer, and
+    lectured on astronomical subjects in this country, and in
+    England and her colonies. A memorial teaching observatory is
+    erected in his honor near San Diego, Cal. He was a man of
+    untiring industry, an athlete, a musician, and a chess-player.
+    His books are numerous. Among them are "Half Hours with the
+    Telescope," "Other Worlds than Ours," "Light Science for
+    Leisure Hours," "The Expanse of Heaven," "The Moon," "The
+    Borderland of Science," "Our Place Among Infinites," "Myths and
+    Marvels of Astronomy," "The Universe of Suns," "Other Suns than
+    Ours," etc.</p>
+
+    <p><span class="sc">Shaler, N.S.</span>, professor of geology
+    at Harvard. Born Newport, Ky., 1841. Served in the Union Army
+    during the Civil War. Instructor zoölogy, geology, and
+    paleontology, Lawrence Scientific School, till 1887. Since then
+    at Harvard. Is the author of "Kentucky a Pioneer Commonwealth,"
+    "The Story of Our Continent," "The Interpretation of Nature,"
+    "Feature of Coasts and Oceans," "Domesticated Animals," "The
+    Individual," "Study of Life and Death," etc.</p>
+
+    <p><span class="sc">Thompson, Sir C. Wyville</span>, English
+    zoölogist, born, 1830; died, 1882. He conducted scientific
+    dredging expeditions in the <i>Lightning</i> and
+    <i>Porcupine</i>, 1868-69, and was the scientific head of the
+    famous voyage of 68,900 miles in the <i>Challenger</i> for
+    deep-sea explorations (1872-76). His books are "The Depths of
+    the Sea," and "The Voyage of the Challenger."</p>
+
+    <p><span class="sc">Tyndall, John</span>, English physicist,
+    born, 1820. Began his original researches in 1847, when teacher
+    of physics in Queenwood College. He and Professor Huxley
+    visited the Alps together, and they wrote a work on the
+    structure and nature of glaciers. It is impossible to detail
+    the work he has done; but his inquiries and experiments in
+    connection with light, heat, sound, and electricity have all
+    had practical results. He is a popular lecturer, and devoted
+    the proceeds of a lecturing tour in this country to founding
+    scholarships at Harvard and Columbia Colleges, for students
+    devoting themselves to original research. Among his books are
+    "Glaciers of the Alps," "Mountaineering," "Heat as a Mode of
+    Motion," "On Radiation," "Hours of Exercise in the Alps,"
+    "Fragments of Science," "The Floating Matter of the Air," and
+    volumes on Light, Sound, Electricity, and the forms of
+    water.</p>
+
+    <p><span class="sc">Wallace, A.R.</span>, English naturalist
+    and traveller, born 1822; was educated as land surveyor and
+    architect, but afterwards devoted himself entirely to Natural
+    History. He explored the Valley of the Amazon and Rio Negro,
+    1848-52, and travelled in the Malay Archipelago and Papua,
+    1854-62, publishing the results of his explorations later on.
+    He also wrote "Contributions to the Theory of Natural
+    Selection," "Miracles and Modern Spiritualism," "Geographical
+    Distribution of Animals," "Tropical Nature," "Island Life,"
+    etc.</p>
+
+    <p><span class="sc">Giberne, Agnes</span>, English
+    author&mdash;living. Began to write at seven years old. Her
+    first story for children was published when she was only
+    seventeen. Her stories for children have not been so popular as
+    her scientific writings, "Sun, Moon, and Stars," "The Starry
+    Skies," "Among the Stars," "The Ocean of Air," "The World's
+    Foundations," "Radiant Suns," etc.</p>
+
+    <p><span class="sc">Wilson, Andrew</span>, English physiologist
+    and lecturer, born, 1852. Is the author of "Studies on Life and
+    Sense," "Leisure Time Studies," "Science Stories," "Chapters on
+    Evolution," "Wild Animals," "Brain and Nerve," etc., and is a
+    constant contributor on scientific subjects to the magazines
+    and newspapers, contributing weekly "Science Jottings" to the
+    "Illustrated London News"</p>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a id="page389"></a>[pg 389]</span>
+
+    <h2>WONDERS OF EARTH, SEA, AND SKY</h2>
+
+    <h3>SUGGESTIONS FOR SUPPLEMENTARY READING</h3>
+
+    <div class="poem">
+        <div class="stanza">
+            <p>Wonder Stories of Science</p>
+
+            <p class="i2">D.N. BEACH</p>
+        </div>
+
+        <div class="stanza">
+            <p>Wonders in Monsterland</p>
+
+            <p class="i2">EDWARD W.D. CUMING</p>
+        </div>
+
+        <div class="stanza">
+            <p>Ocean Wonders</p>
+
+            <p class="i2">W.E. DAMON</p>
+        </div>
+
+        <div class="stanza">
+            <p>Among the Stars</p>
+
+            <p class="i2">AGNES GIBERNE</p>
+        </div>
+
+        <div class="stanza">
+            <p>The Scenery of the Heavens</p>
+
+            <p class="i2">JOHN ELLARD GORR</p>
+        </div>
+
+        <div class="stanza">
+            <p>Coal and the Coal Miners</p>
+
+            <p class="i2">HOMER GREENE</p>
+        </div>
+
+        <div class="stanza">
+            <p>Wonders of the Moon</p>
+
+            <p class="i2">A. GUILLEMIN</p>
+        </div>
+
+        <div class="stanza">
+            <p>The Sea and Its Living Wonders.</p>
+
+            <p class="i2">G. HARTWIG</p>
+        </div>
+
+        <div class="stanza">
+            <p>The Wonders of Plant Life Under the Microscope</p>
+
+            <p class="i2">SOPHIE B. HERRICK</p>
+        </div>
+
+        <div class="stanza">
+            <p>Marvels of Animal Life</p>
+
+            <p class="i2">CHARLES F. HOLDER</p>
+        </div>
+
+        <div class="stanza">
+            <p>Old Ocean</p>
+
+            <p class="i2">ERNEST INGERSOLL</p>
+        </div>
+
+        <div class="stanza">
+            <p>Modern Seven Wonders of the World</p>
+
+            <p class="i2">C. KENT</p>
+        </div>
+
+        <div class="stanza">
+            <p>Madam How and Lady Why</p>
+
+            <p class="i2">CHARLES KINGSLEY</p>
+        </div>
+
+        <div class="stanza">
+            <p>Wonders of Optics</p>
+
+            <p class="i2">F. MARION</p>
+        </div>
+
+        <div class="stanza">
+            <p>The Wonders of Science</p>
+
+            <p class="i2">HENRY MAYHEW</p>
+        </div>
+
+        <div class="stanza">
+            <p>Wonders of Man and Nature</p>
+
+            <p class="i2">E. MENAULT</p>
+        </div>
+
+        <div class="stanza">
+            <p>A Century of Electricity</p>
+
+            <p class="i2">T.C. MENDENHALL</p>
+        </div>
+
+        <div class="stanza">
+            <p>The Orbs of Heaven</p>
+
+            <p class="i2">ORMSBY S. MITCHELL</p>
+        </div>
+
+        <div class="stanza">
+            <p>Under Foot</p>
+
+            <p class="i2">LAURA D. NICHOLS</p>
+        </div>
+
+        <div class="stanza">
+            <p>Myths and Marvels of Astronomy</p>
+
+            <p class="i2">R.A. PROCTOR</p>
+        </div>
+
+        <div class="stanza">
+            <p>The Wonders of the World</p>
+
+            <p class="i2">CHARLES G. ROSENBERG</p>
+        </div>
+
+        <div class="stanza">
+            <p>The Wonders of Nature</p>
+
+            <p class="i2">PROFESSOR RUDOLPH</p>
+        </div>
+
+        <div class="stanza">
+            <p>Volcanoes of North America</p>
+
+            <p class="i2">ISRAEL COOK RUSSELL</p>
+        </div>
+
+        <div class="stanza">
+            <p>Aspects of the Earth</p>
+
+            <p class="i2">N.S. SHALER</p>
+        </div>
+
+        <div class="stanza">
+            <p>Wonders of the Bird World</p>
+
+            <p class="i2">R.B. SHARPE</p>
+        </div>
+
+        <div class="stanza">
+            <p>The Wonders of Water</p>
+
+            <p class="i2">GASTON TISSANDIER</p>
+        </div>
+
+        <div class="stanza">
+            <p>Total Eclipses of the Sun</p>
+
+            <p class="i2">MABEL L. TODD</p>
+        </div>
+
+        <div class="stanza">
+            <p>Wonders of Insect Life</p>
+
+            <p class="i2">JOSEPH C. WILLET</p>
+        </div>
+    </div>
+
+    <p>&nbsp;</p>
+    <hr>
+
+    <blockquote class="footnote">
+        <a id="footnote1"></a><b>Footnote 1:</b>
+                    <a href="#footnotetag1">(return)</a>
+
+        <p>Copyright, 1884, by N.S. Shaler.</p>
+    </blockquote>
+
+    <blockquote class="footnote">
+        <a id="footnote2"></a><b>Footnote 2:</b>
+                    <a href="#footnotetag2">(return)</a>
+
+        <p>During the cruise of H.M.S. Bull-dog, commanded by Sir
+        Leopold M'Clintock, in 1860, living star-fish were brought
+        up, clinging to the lowest part of the sounding-line, from
+        a depth of 1260 fathoms, midway between Cape Farewell, in
+        Greenland, and the Rockall banks. Dr. Wallich ascertained
+        that the sea-bottom at this point consisted of the ordinary
+        Globigerina ooze, and that the stomachs of the star-fishes
+        were full of Globigerinæ. This discovery removes all
+        objections to the existence of living Globigerinæ at great
+        depths, which are based upon the supposed difficulty of
+        maintaining animal life under such conditions; and it
+        throws the burden of proof upon those who object to the
+        supposition that the Globigerinæ live and die where they
+        are found.</p>
+    </blockquote>
+
+    <blockquote class="footnote">
+        <a id="footnote3"></a><b>Footnote 3:</b>
+                    <a href="#footnotetag3">(return)</a>
+
+        <p>I have recently traced out the development of the
+        "coccoliths" from a diameter of 1/7000th of an inch up to
+        their largest size (which is about 1/1600th), and no longer
+        doubt that they are produced by independent organisms,
+        which, like the Globigerinæ, live and die at the bottom of
+        the sea.</p>
+    </blockquote>
+
+    <blockquote class="footnote">
+        <a id="footnote4"></a><b>Footnote 4:</b>
+                    <a href="#footnotetag4">(return)</a>
+
+        <p>The slice given in Fig. 2 is from a broader-leaved form,
+        <i>U. lactuca</i>, because this species, being composed of
+        only one layer of cells, is better seen. <i>Ulva Linza</i>
+        is composed of two layers of cells.</p>
+    </blockquote>
+
+<p>&nbsp;</p>
+
+<div>*** END OF THE PROJECT GUTENBERG EBOOK 15884 ***</div>
+</body>
+</html>
+
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+This eBook, including all associated images, markup, improvements,
+metadata, and any other content or labor, has been confirmed to be
+in the PUBLIC DOMAIN IN THE UNITED STATES.
+
+Procedures for determining public domain status are described in
+the "Copyright How-To" at https://www.gutenberg.org.
+
+No investigation has been made concerning possible copyrights in
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+status under the laws that apply to them.
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+Project Gutenberg (https://www.gutenberg.org) public repository for
+eBook #15884 (https://www.gutenberg.org/ebooks/15884)
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+The Project Gutenberg eBook, Young Folks' Library, Volume XI (of 20), by
+Various, Edited by Edward Singleton Holden
+
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+
+
+
+Title: Young Folks' Library, Volume XI (of 20)
+       Wonders of Earth, Sea and Sky
+
+
+Author: Various
+
+Editor: Edward Singleton Holden
+
+Release Date: May 23, 2005  [eBook #15884]
+[Last updated: August 31, 2022]
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+
+***START OF THE PROJECT GUTENBERG EBOOK YOUNG FOLKS' LIBRARY, VOLUME XI
+(OF 20)***
+
+
+E-text prepared by Juliet Sutherland, Sandra Brown, and the Project
+Gutenberg Online Distributed Proofreading Team
+
+
+
+Note: Project Gutenberg also has an HTML version of this
+      file which includes the original illustrations.
+      See 15884-h.htm or 15884-h.zip:
+      (https://www.gutenberg.org/dirs/1/5/8/8/15884/15884-h/15884-h.htm)
+      or
+      (https://www.gutenberg.org/dirs/1/5/8/8/15884/15884-h.zip)
+
+
+
+
+
+Young Folks' Library
+
+Selections from the Choicest Literature of All
+Lands; Folk-Lore, Fairy Tales, Fables, Legends,
+Natural History, Wonders of Earth, Sea
+and Sky, Animal Stories, Sea Tales,
+Brave Deeds, Explorations, Stories
+of School and College Life,
+Biography, History, Patriotic
+Eloquence, Poetry
+
+Third Edition
+
+Revised in Conference by
+
+   Thomas Bailey Aldrich, Editor-in-Chief,
+   President William Jewett Tucker,
+   Hamilton Wright Mabie,
+   Henry Van Dyke,
+   Nathan Haskell Dole
+
+Twenty Volumes   Richly Illustrated
+
+Boston
+Hall and Locke Company
+Publishers
+Stanhope Press
+F.H. Gilson Company
+Boston, U.S.A.
+
+1902
+
+
+
+
+
+
+EDITORIAL BOARD
+
+
+   THOMAS BAILEY ALDRICH, Editor-in-chief,
+   Author, poet, former editor _Atlantic Monthly,_ Boston, Mass.
+
+   The HON. JOHN D. LONG,
+   Secretary of the United States Navy, Boston.
+
+   HAMILTON WRIGHT MABIE, LL.D.,
+   Author, literarian, associate editor _The Outlook_, New York.
+
+   ERNEST THOMPSON SETON,
+   Artist, author, New York.
+
+   JOHN TOWNSEND TROWBRIDGE,
+   Author, poet, and editor, Arlington, Mass.
+
+   The REVEREND CYRUS TOWNSEND BRADY,
+   Archdeacon, author, Philadelphia.
+
+   JOEL CHANDLER HARRIS,
+   Humorous writer, Atlanta, Ga.
+
+   MARY HARTWELL CATHERWOOD,
+   Historical novelist, Chicago.
+
+   LAURA E. RICHARDS,
+   Author, Gardiner, Me.
+
+   ROSWELL FIELD,
+   Author, editor _The Evening Post>_, Chicago.
+
+   TUDOR JENKS,
+   Author, associate editor _Saint Nicholas_, New York.
+
+   GEORGE A. HENTY,
+   Traveller, author, London, England.
+
+   KIRK MUNROE,
+   Writer of stories for boys, Cocoanut Grove, Fla.
+
+   EDITH M. THOMAS,
+   Poet, West New Brighton, N.Y.
+
+   CAROLINE TICKNOR,
+   Author, editor, Boston.
+
+   NATHAN HASKELL DOLE,
+   Author, translator, literary editor _Current History_, Boston.
+
+   WILLIAM RAINEY HARPER, D.D., LL.D.,
+   President Chicago University.
+
+   DAVID STARR JORDAN, M.D., LL.D.,
+   President Leland Stanford Junior University, naturalist, writer,
+   Stanford University, Cal.
+
+   CHARLES ELIOT NORTON, A.M., LL.D., etc.,
+   Scholar, author, Emeritus Professor of Art at Harvard University.
+
+   HENRY VAN DYKE, D.D., LL.D.,
+   Clergyman, author, Professor Princeton University.
+
+   The REVEREND THOMAS J. SHAHAN,
+   Dean of the Faculty of Divinity, Professor of Early Ecclesiastical
+   History, Catholic University, Washington, D.C.
+
+   WILLIAM P. TRENT,
+   Author, editor, Professor of English Literature, Columbia University,
+   New York City.
+
+   EDWARD SINGLETON HOLDEN, A.M., LL.D.,
+   Ex-president University of California, astronomer, author,
+   U.S. Military Academy, West Point.
+
+   EDWIN ERLE SPARKS,
+   Professor of American History, Chicago University.
+
+   The VERY REV. GEORGE M. GRANT, D.D., LL.D.,
+   Educator, author, vice-principal Queen's College, Kingston, Ont.
+
+   BARONESS VON BULOW,
+   Educator, author, Dresden, Germany.
+
+   ABBIE FARWELL BROWN,
+   Author, Boston.
+
+   CHARLES WELSH, Managing Editor,
+   Author, lecturer, editor, Winthrop Highlands, Mass.
+
+
+
+
+
+LIST OF VOLUMES
+
+
+   VOLUME I.
+
+   THE STORY TELLER
+   Edited by CHARLES ELIOT NORTON
+
+
+   VOLUME II.
+
+   THE MERRY MAKER
+   Edited by JOEL CHANDLER HARRIS
+
+
+   VOLUME III.
+
+   FAMOUS FAIRY TALES
+   Edited by ROSWELL FIELD
+
+
+   VOLUME IV.
+
+   TALES OF FANTASY
+   Edited by TUDOR JENKS
+
+
+   VOLUME V.
+   MYTHS AND LEGENDS
+   Edited by THOMAS J. SHAHAN
+
+
+   VOLUME VI.
+
+   THE ANIMAL STORY BOOK
+   Edited by ERNEST THOMPSON SETON
+
+
+   VOLUME VII.
+
+   SCHOOL AND COLLEGE DAYS
+   Edited by KIRK MUNROE and
+   MARY HARTWELL CATHERWOOD
+
+
+   VOLUME VIII.
+
+   BOOK OF ADVENTURE
+   Edited by NATHAN HASKELL DOLE
+
+
+   VOLUME IX.
+
+   FAMOUS EXPLORERS
+   Edited by EDWIN ERLE SPARKS
+
+
+   VOLUME X.
+
+   BRAVE DEEDS
+   Edited by JOHN TOWNSEND TROWBRIDGE
+
+
+   VOLUME XI.
+
+   WONDERS OF EARTH, SEA AND SKY
+   Edited by EDWARD SINGLETON HOLDEN
+
+
+   VOLUME XII.
+
+   FAMOUS TRAVELS
+   Edited by GEORGE A. HENTY
+
+
+   VOLUME XIII.
+
+   SEA STORIES
+   Edited by CYRUS TOWNSEND BRADY
+
+
+   VOLUME XIV.
+
+   A BOOK OF NATURAL HISTORY
+   Edited by DAVID STARR JORDAN
+
+
+   VOLUME XV.
+
+   HISTORIC SCENES IN FICTION
+   Edited by HENRY VAN DYKE
+
+
+   VOLUME XVI.
+
+   FAMOUS BATTLES BY LAND AND SEA
+   Edited by JOHN D. LONG
+
+
+   VOLUME XVII.
+
+   MEN WHO HAVE RISEN
+   Edited by HAMILTON WRIGHT MABIE.
+
+
+   VOLUME XVIII.
+
+   BOOK OF PATRIOTISM
+   Edited by
+
+
+   VOLUME XIX.
+
+   LEADERS OF MEN, OR HISTORY TOLD IN BIOGRAPHY
+   Edited by WILLIAM RAINEY HARPER
+
+
+   VOLUME XX.
+
+   FAMOUS POEMS
+   Selected by THOMAS BAILEY ALDRICH,
+   with Poetical Foreword by EDITH M. THOMAS.
+
+
+
+[Illustration: A GEYSER]
+
+
+
+
+
+Volume XI: WONDERS OF EARTH, SEA AND SKY
+
+Edited by EDWARD SINGLETON HOLDEN
+
+Boston
+Hall and Locke Company Publishers
+
+1902
+
+
+
+
+
+CONTENTS
+
+
+  LIST OF ILLUSTRATIONS                xi
+
+  THE MARVELS OF NATURE              xiii
+  BY PROFESSOR E.S. HOLDEN.
+
+  WHAT THE EARTH'S CRUST IS MADE OF     1
+  BY AGNES GIBERNE.
+
+  AMERICA THE OLD WORLD                45
+  BY LOUIS AGASSIZ.
+
+  SOME RECORDS OF THE ROCKS            77
+  BY N.S. SHALER.
+
+  THE PITCH LAKE IN THE WEST INDIES    97
+  BY CHARLES KINGSLEY.
+
+  A STALAGMITE CAVE                   111
+  BY SIR C. WYVILLE THOMSON.
+
+  THE BIG TREES OF CALIFORNIA         119
+  BY ALFRED RUSSEL WALLACE.
+
+  WHAT IS EVOLUTION?                  127
+  BY PROFESSOR EDWARD S. HOLDEN.
+
+  HOW THE SOIL IS MADE                135
+  BY CHARLES DARWIN.
+
+  ZOÖLOGICAL MYTHS                    143
+  BY ANDREW WILSON.
+
+  ON A PIECE OF CHALK                 171
+  BY T.H. HUXLEY.
+
+  A BIT OF SPONGE                     205
+  BY A. WILSON.
+
+  THE GREATEST SEA-WAVE EVER KNOWN    211
+  BY R.A. PROCTOR.
+
+  THE PHOSPHORESCENT SEA              228
+  BY W.S. DALLAS.
+
+  COMETS                              251
+  BY CAMILLE FLAMMARION.
+
+  THE TOTAL SOLAR ECLIPSE OF 1883     261
+  BY E.S. HOLDEN.
+
+  HALOS--PARHELIA--THE SPECTRE OF
+    THE BROCKEN, ETC.                 268
+  BY CAMILLE FLAMMARION.
+
+  THE PLANET VENUS                    282
+  BY AGNES M. CLERKE.
+
+  THE STARS                           296
+  BY SIR R.S. BALL.
+
+  RAIN AND SNOW                       342
+  BY JOHN TYNDALL.
+
+  THE ORGANIC WORLD                   357
+  BY ST. GEORGE MIVART.
+
+  INHABITANTS OF MY POOL              366
+  BY ARABELLA B. BUCKLEY.
+
+  BIOGRAPHICAL NOTES.                 387
+
+  SUGGESTIONS FOR SUPPLEMENTARY
+    READING.                          389
+
+
+NOTE.
+
+The publishers' acknowledgments are due to Messrs. Houghton, Mifflin &
+Co., for permission to use "America and the Old World," by L. Agassiz;
+to Messrs. D.C. Heath & Co. for permission to use "Some Records of the
+Rocks," by Professor N.S. Shaler; and to Professor E.S. Holden for
+permission to use "What is Evolution?" and "An Astronomer's Voyage to
+Fairy Land."
+
+
+
+
+LIST OF COLORED ILLUSTRATIONS
+
+  A GEYSER. _Frontispiece,  See Page_  47
+
+  VIEW IN A CAÑON         _Face Page_  12
+
+  A VOLCANO                            48
+
+  A STALAGMITE CAVE                   116
+
+  WHERE SPONGES GROW                  208
+
+  A COMET                             254
+
+  THE SPECTRE OF THE BROCKEN          272
+
+
+AND ONE HUNDRED AND SIXTY-FOUR BLACK AND WHITE ILLUSTRATIONS IN THE
+TEXT.
+
+
+
+
+THE MARVELS OF NATURE
+
+BY EDWARD S. HOLDEN, M.A., Sc.D. LL.D.
+
+
+The Earth, the Sea, the Sky, and their wonders--these are the themes
+of this volume. The volume is so small, and the theme so vast! Men
+have lived on the earth for hundreds of thousands of years; and its
+wonders have increased, not diminished, with their experience.
+
+To our barbarous ancestors of centuries ago, all was mystery--the
+thunder, the rainbow, the growing corn, the ocean, the stars.
+Gradually and by slow steps they learned to house themselves in trees,
+in caves, in huts, in houses; to find a sure supply of food; to
+provide a stock of serviceable clothing. The arts of life were born;
+tools were invented; the priceless boon of fire was received; tribes
+and clans united for defence; some measure of security and comfort was
+attained.
+
+With security and comfort came leisure; and the mind of early Man
+began curiously to inquire the meaning of the mysteries with which he
+was surrounded. That curious inquiry was the birth of Science. Art was
+born when some far-away ancestor, in an idle hour, scratched on a
+bone the drawing of two of his reindeer fighting, or carved on the
+walls of his cave the image of the mammoth that he had but lately
+slain with his spear and arrows.
+
+In a mind that is completely ignorant there is no wonder. Wonder is
+the child of knowledge--of partial and imperfect knowledge, to be
+sure, but still, of knowledge. The very first step in Science is to
+make an inventory of external Nature (and by and by of the faculties
+of the mind that thinks). The second step is to catalogue similar
+appearances together. It is a much higher flight to seek the causes of
+likenesses thus discovered.
+
+A few of the chapters of this volume are items in a mere catalogue of
+wonders, and deserve their place by accurate and eloquent description.
+Most of them, however, represent higher stages of insight. In the
+latter, Nature is viewed not only with the eye of the observer, but
+also with the mind's eye, curious to discover the reasons for things
+seen. The most penetrating inward inquiry accompanies the acutest
+external observation in such chapters as those of Darwin and Huxley,
+here reprinted.
+
+Now, the point not to be overlooked is this: to Darwin and Huxley, as
+to their remote and uncultured ancestors, the World--the Earth, the
+Sea, the Sky--is full of wonders and of mysteries, but the wonders are
+of a higher order. The problems of the thunder and of the rainbow as
+they presented themselves to the men of a thousand generations ago,
+have been fully solved: but the questions; what is the veritable
+nature of electricity, exactly how does it differ from light, are
+still unanswered. And what are simple problems like these to the
+questions: what is love; why do we feel a sympathy with this person,
+an antipathy for that; and others of the sort? Science has made almost
+infinite advances since pre-historic man first felt the feeble current
+of intellectual curiosity amid his awe of the storm; it has still to
+grow almost infinitely before anything like a complete explanation
+even of external Nature is achieved.
+
+Suppose that, at some future day, all physical and mechanical laws
+should be found to be direct consequences of a single majestic law,
+just as all the motions of the planets are (but--are they?) the direct
+results of the single law of gravitation. Gravitation will, probably,
+soon be explained in terms of some remoter cause, but the reason of
+that single and ultimate law of the universe which we have imagined
+would still remain unknown. Human knowledge will always have limits,
+and beyond those limits there will always be room for mystery and
+wonder. A complete and exhaustive explanation of the world is
+inconceivable, so long as human powers and capacities remain at all as
+they now are.
+
+It is important to emphasize such truths, especially in a book
+addressed to the young. When a lad hears for the first time that an
+astronomer, by a simple pointing of his spectroscope, can determine
+with what velocity a star is approaching the earth, or receding from
+it, or when he hears that the very shape of the revolving masses of
+certain stars can be calculated from simple measures of the sort, he
+is apt to conclude that Science, which has made such astounding
+advances since the days of Galileo and Newton, must eventually reach a
+complete explanation of the entire universe. The conclusion is not
+unnatural, but it is not correct. There are limits beyond which
+Science, in this sense, cannot go. Its scope is limited. Beyond its
+limits there are problems that it cannot solve, mysteries that it
+cannot explain.
+
+At the present moment, for example, the nature of Force is unknown. A
+weight released from the hand drops to the earth. Exactly what is the
+nature of the force with which the earth attracts it? We do not know,
+but it so happens that it is more than likely that an explanation will
+be reached in our own day. Gravity will be explained in terms of some
+more general forces. The mystery will be pushed back another step, and
+yet another and another. But the progress is not indefinite. If all
+the mechanical actions of the entire universe were to be formulated as
+the results of a single law or cause, the cause of that cause would be
+still to seek, as has been said.
+
+We have every right to exult in the amazing achievements of Science;
+but we have not understood them until we realize that the universe of
+Science has strict limits, within which all its conquests must
+necessarily be confined. Humility, and not pride, is the final lesson
+of scientific work and study.
+
+       *       *       *       *       *
+
+The choice of the selections printed in this volume has been
+necessarily limited by many hampering conditions, that of mere space
+being one of the most harassing. Each of the chapters might readily be
+expanded into a volume. Volumes might be added on topics almost
+untouched here. It has been necessary to pass over almost without
+notice matters of surpassing interest and importance: Electricity and
+its wonderful and new applications; the new Biology, with its views
+upon such fundamental questions as the origins of life and death;
+modern Astronomy, with its far-reaching pronouncements upon the fate
+of universes. All these can only be touched lightly, if at all. It is
+the chief purpose of this volume to point the way towards the most
+modern and the greatest conclusions of Science, and to lay foundations
+upon which the reading of a life-time can be laid.
+
+[Illustration: Signature: Edward S. Holden]
+
+UNITED STATES MILITARY ACADEMY, WEST POINT, _January 1, 1902_.
+
+
+
+
+WONDERS OF EARTH, SEA, AND SKY
+
+
+
+
+WHAT THE EARTH'S CRUST IS MADE OF
+
+(FROM THE WORLD'S FOUNDATIONS.)
+
+BY AGNES GIBERNE.
+
+
+     "Stand still and consider the wondrous works of God."
+
+[Illustration]
+
+What is the earth made of--this round earth upon which we human beings
+live and move?
+
+A question more easily asked than answered, as regards a very large
+portion of it. For the earth is a huge ball nearly eight thousand
+miles in diameter, and we who dwell on the outside have no means of
+getting down more than a very little way below the surface. So it is
+quite impossible for us to speak positively as to the inside of the
+earth, and what it is made of. Some people believe the earth's inside
+to be hard and solid, while others believe it to be one enormous lake
+or furnace of fiery melted rock. But nobody really knows.
+
+This outside crust has been reckoned to be of many different
+thicknesses. One man will say it is ten miles thick, and another will
+rate it at four hundred miles. So far as regards man's knowledge of
+it, gained from mining, from boring, from examination of rocks, and
+from reasoning out all that may be learned from these observations, we
+shall allow an ample margin if we count the field of geology to extend
+some twenty miles downwards from the highest mountain-tops. Beyond
+this we find ourselves in a land of darkness and conjecture.
+
+Twenty miles is only one four-hundredth part of the earth's
+diameter--a mere thin shell over a massive globe. If the earth were
+brought down in size to an ordinary large school globe, a piece of
+rough brown paper covering it might well represent the thickness of
+this earth-crust, with which the science of geology has to do. And the
+whole of the globe, this earth of ours, is but one tiny planet in the
+great Solar System. And the centre of that Solar System, the blazing
+sun, though equal in size to more than a million earths, is yet
+himself but one star amid millions of twinkling stars, scattered
+broadcast through the universe. So it would seem at first sight that
+the field of geology is a small field compared with that of
+astronomy....
+
+With regard to the great bulk of the globe little can be said. Very
+probably it is formed through and through of the same materials as the
+crust. This we do not know. Neither can we tell, even if it be so
+formed, whether the said materials are solid and cold like the
+outside crust, or whether they are liquid with heat. The belief has
+been long and widely held that the whole inside of the earth is one
+vast lake or furnace of melted fiery-hot material, with only a thin
+cooled crust covering it. Some in the present day are inclined to
+question this, and hold rather that the earth is solid and cold
+throughout, though with large lakes of liquid fire here and there,
+under or in her crust, from which our volcanoes are fed....
+
+The materials of which the crust is made are many and various; yet,
+generally speaking, they may all be classed under one simple word, and
+that word is--_Rock_.
+
+It must be understood that, when we talk of rock in this geological
+sense, we do not only mean hard and solid stone, as in common
+conversation. Rock may be changed by heat into a liquid or "molten"
+state, as ice is changed by heat to water. Liquid rock may be changed
+by yet greater heat to vapor, as water is changed to steam, only we
+have in a common way no such heat at command as would be needed to
+effect this. Rock may be hard or soft. Rock maybe chalky, clayey, or
+sandy. Rock may be so close-grained that strong force is needed to
+break it; or it may be so porous--so full of tiny holes--that water
+will drain through it; or it may be crushed and crumbled into loose
+grains, among which you can pass your fingers.
+
+The cliffs above our beaches are rock; the sand upon our seashore is
+rock; the clay used in brick-making is rock; the limestone of the
+quarry is rock; the marble of which our mantel-pieces are made is
+rock. The soft sandstone of South Devon, and the hard granite of the
+north of Scotland, are alike rock. The pebbles in the road are rock;
+the very mould in our gardens is largely composed of crumbled rock. So
+the word in its geological sense is a word of wide meaning.
+
+Now the business of the geologist is to read the history of the past
+in these rocks of which the earth's crust is made. This may seem a
+singular thing to do, and I can assure you it is not an easy task.
+
+For, to begin with, the history itself is written in a strange
+language, a language which man is only just beginning to spell out and
+understand. And this is only half the difficulty with which we have to
+struggle.
+
+If a large and learned book were put before you and you were set to
+read it through, you would perhaps, have no insurmountable difficulty,
+with patience and perseverance, in mastering its meaning.
+
+But how if the book were first chopped up into pieces, if part of it
+were flung away out of reach, if part of it were crushed into a pulp,
+if the numbering of the pages were in many places lost, if the whole
+were mixed up in confusion, and if _then_ you were desired to sort,
+and arrange, and study the volume?
+
+Picture to yourself what sort of a task this would be, and you will
+have some idea of the labors of the patient geologist.
+
+Rocks may be divided into several kinds or classes. For the present
+moment it will be enough to consider the two grand divisions--_Stratified
+rocks_ and _Unstratified rocks_.
+
+Unstratified rocks are those which were once, at a time more or less
+distant, in a melted state from intense heat, and which have since
+cooled into a half _crystallized_ state; much the same as water, when
+growing colder, cools and crystallizes into ice. Strictly speaking,
+ice is rock, just as much as granite and sandstone are rock. Water
+itself is of the nature of rock, only as we commonly know it in the
+liquid state we do not commonly call it so.
+
+[Illustration: UNSTRATIFIED ROCK.--A VOLCANIC BLOCK.]
+
+"Crystallization" means those particular forms or shapes in which the
+particles of a liquid arrange themselves, as that liquid hardens into
+a solid--in other words, as it freezes. Granite, iron, marble, are
+frozen substances, just as truly as ice is a frozen substance; for
+with greater heat they would all become liquid like water. When a
+liquid freezes, there are always crystals formed, though these are not
+always visible without the help of a microscope. Also the crystals are
+of different shapes with different substances.
+
+If you examine the surface of a puddle or pond, when a thin covering
+of ice is beginning to form, you will be able to see plainly the
+delicate sharp needle-like forms of the ice crystals. Break a piece of
+ice, and you will find that it will not easily break just in any way
+that you may choose, but it will only split along the lines of these
+needle-like crystals. This particular mode of splitting in a
+crystallized rock is called the _cleavage_ of that rock.
+
+Crystallization may take place either slowly or rapidly, and either
+in the open air or far below ground. The lava from a volcano is an
+example of rock which has crystallized rapidly in the open air; and
+granite is an example of rock which has crystallized slowly
+underground beneath great pressure.
+
+Stratified rocks, on the contrary, which make up a very large part of
+the earth's crust, are not crystallized. Instead of having cooled from
+a liquid into a solid state, they have been slowly _built up_, bit by
+bit and grain upon grain, into their present form, through long ages
+of the world's history. The materials of which they are made were
+probably once, long, long ago, the crumblings from granite and other
+crystallized rocks, but they show now no signs of crystallization.
+
+
+[Illustration: SECTION OF STRATIFIED ROCKS.
+
+_a._ Conglomerate. _b._ Pebbly Sandstone, _c._ Thin-bedded Sandstone,
+_d._ Shelly Sandstone, _e._ Shale. _f._ Limestone.]
+
+They are called "stratified" because they are in themselves made up of
+distinct layers, and also because they lie thus one upon another in
+layers, or _strata_, just as the leaves of a book lie, or as the
+bricks of a house are placed.
+
+Throughout the greater part of Europe, of Asia, of Africa, of North
+and South America, of Australia, these rocks are to be found,
+stretching over hundreds of miles together, north, south, east, and
+west, extending up to the tops of some of the earth's highest
+mountains, reaching down deep into the earth's crust. In many parts if
+you could dig straight downwards through the earth for thousands of
+feet, you would come to layer after layer of these stratified rocks,
+one kind below another, some layers thick, some layers thin, here a
+stratum of gravel, there a stratum of sandstone, here a stratum of
+coal, there a stratum of clay.
+
+But how, when, where, did the building up of all these rock-layers
+take place?
+
+[Illustration: THE BEACH IN THE FOREGROUND IS A ROCKY SHELF, THE
+REMNANT OF THE CLIFF WHICH ONCE EXTENDED OUT TO THE ISLAND.]
+
+
+People are rather apt to think of land and water on the earth as if
+they were fixed in one changeless form,--as if every continent and
+every island were of exactly the same shape and size now that it
+always has been and always will be.
+
+Yet nothing can be further from the truth. The earth-crust is a scene
+of perpetual change, of perpetual struggle, of perpetual building up,
+of perpetual wearing away.
+
+The work may go on slowly, but it does go on. The sea is always
+fighting against the land, beating down her cliffs, eating into her
+shores, swallowing bit by bit of solid earth; and rain and frost and
+inland streams are always busily at work, helping the ocean in her
+work of destruction. Year by year and century by century it continues.
+Not a country in the world which is bordered by the open sea has
+precisely the same coast-line that it had one hundred years ago; not a
+land in the world but parts each century with masses of its material,
+washed piecemeal away into the ocean.
+
+Is this hard to believe? Look at the crumbling cliffs around old
+England's shores. See the effect upon the beach of one night's fierce
+storm. Mark the pathway on the cliff, how it seems to have crept so
+near the edge that here and there it is scarcely safe to tread; and
+very soon, as we know, it will become impassable. Just from a mere
+accident, of course,--the breaking away of some of the earth, loosened
+by rain and frost and wind. But this is an accident which happens
+daily in hundreds of places around the shores.
+
+Leaving the ocean, look now at this river in our neighborhood, and see
+the slight muddiness which seems to color its waters. What from? Only
+a little earth and sand carried off from the banks as it flowed,--very
+unimportant and small in quantity, doubtless, just at this moment and
+just at this spot. But what of that little going on week after week,
+and century after century, throughout the whole course of the river,
+and throughout the whole course of every river and rivulet in our
+whole country and in every other country. A vast amount of material
+must every year be thus torn from the land and given to the ocean. For
+the land's loss here is the ocean's gain.
+
+And, strange to say, we shall find that this same ocean, so busily
+engaged with the help of its tributary rivers in pulling down land, is
+no less busily engaged with their help in building it up.
+
+You have sometimes seen directions upon a vial of medicine to "shake"
+before taking the dose. When you have so shaken the bottle the clear
+liquid grows thick; and if you let it stand for awhile the thickness
+goes off, and a fine grain-like or dust-like substance settles down at
+the bottom--the settlement or _sediment_ of the medicine. The finer
+this sediment, the slower it is in settling. If you were to keep the
+liquid in gentle motion, the fine sediment would not settle down at
+the bottom. With coarser and heavier grains the motion would have to
+be quicker to keep them supported in the water.
+
+Now it is just the same thing with our rivers and streams. Running
+water can support and carry along sand and earth, which in still water
+would quickly sink to the bottom; and the more rapid the movement of
+the water, the greater is the weight it is able to bear.
+
+This is plainly to be seen in the case of a mountain torrent. As it
+foams fiercely through its rocky bed it bears along, not only mud and
+sand and gravel, but stones and even small rocks, grinding the latter
+roughly together till they are gradually worn away, first to rounded
+pebbles, then to sand, and finally to mud. The material thus swept
+away by a stream, ground fine, and carried out to sea--part being
+dropped by the way on the river-bed--is called _detritus_, which
+simply means _worn-out_ material.
+
+[Illustration: A MOUNTAIN TORRENT.]
+
+The tremendous carrying-power of a mountain torrent can scarcely be
+realized by those who have not observed it for themselves. I have seen
+a little mountain-stream swell in the course of a heavy thunderstorm
+to such a torrent, brown and turbid with earth torn from the
+mountainside, and sweeping resistlessly along in its career a shower
+of stones and rock-fragments. That which happens thus occasionally
+with many streams is more or less the work all the year round of many
+more.
+
+As the torrent grows less rapid, lower down in its course, it ceases
+to carry rocks and stones, though the grinding and wearing away of
+stones upon the rocky bed continues, and coarse gravel is borne still
+upon its waters. Presently the widening stream, flowing yet more
+calmly, drops upon its bed all such coarser gravel as is not worn away
+to fine earth, but still bears on the lighter grains of sand. Next the
+slackening speed makes even the sand too heavy a weight, and that in
+turn falls to line the river-bed, while the now broad and placid
+stream carries only the finer particles of mud suspended in its
+waters. Soon it reaches the ocean, and the flow being there checked by
+the incoming ocean-tide, even the mud can no longer be held up, and it
+also sinks slowly in the shallows near the shore, forming sometimes
+broad mud-banks dangerous to the mariner.
+
+This is the case only with smaller rivers. Where the stream is
+stronger, the mud-banks are often formed much farther out at sea; and
+more often still the river-detritus is carried away and shed over the
+ocean-bed, beyond the reach of our ken. The powerful rush of water in
+earth's greater streams bears enormous masses of sand and mud each
+year far out into the ocean, there dropping quietly the gravel, sand,
+and earth, layer upon layer at the bottom of the sea. Thus pulling
+down and building up go on ever side by side; and while land is the
+theatre oftentimes of decay and loss, ocean is the theatre oftentimes
+of renewal and gain.
+
+
+Did you notice the word "sediment" used a few pages back about the
+settlement at the bottom of a medicine-vial?
+
+There is a second name given to the Stratified Rocks, of which the
+earth's crust is so largely made up. They are called also _Sedimentary
+Rocks_.
+
+The reason is simply this. The Stratified Rocks of the present day
+were once upon a time made up out of the sediment stolen first from
+land and then allowed to settle down on the sea-bottom.
+
+Long, long ago, the rivers, the streams, the ocean, were at work, as
+they are now, carrying away rock and gravel, sand and earth. Then, as
+now, all this material, borne upon the rivers, washed to and fro by
+the ocean, settled down at the mouths of rivers or at the bottom of
+the sea, into a sediment, one layer forming over another, gradually
+built up through long ages. At first it was only a soft, loose, sandy
+or muddy sediment, such as you may see on the seashore, or in a
+mud-bank. But as the thickness of the sediment increased, the weight
+of the layers above gradually pressed the lower layers into firm hard
+rocks; and still, as the work of building went on, these layers were,
+in their turn, made solid by the increasing weight over them. Certain
+chemical changes had also a share in the transformation from soft mud
+to hard rock, which need not be here considered.
+
+All this has through thousands of years been going on. The land is
+perpetually crumbling away; and fresh land under the sea is being
+perpetually built up, from the very same materials which the sea and
+the rivers have so mercilessly stolen from continents and islands.
+This is the way, if geologists rightly judge, in which a very large
+part of the enormous formations of Stratified or Sedimentary Rocks
+have been made.
+
+[Illustration: VIEW IN A CANON.]
+
+So far is clear. But now we come to a difficulty.
+
+The Stratified Rocks, of which a very large part of the continents is
+made, appear to have been built up slowly, layer upon layer, out of
+the gravel, sand, and mud, washed away from the land and dropped on
+the shore of the ocean.
+
+[Illustration: SEA CLIFFS SHOWING A SERIES OF STRATIFIED ROCKS.]
+
+You may see these layers for yourself as you walk out into the
+country. Look at the first piece of bluff rock you come near, and
+observe the clear pencil-like markings of layer above layer--not often
+indeed lying _flat_, one over another, and this must be explained
+later, but however irregularly slanting, still plainly visible. You
+can examine these lines of stratification on the nearest cliff, the
+nearest quarry, the nearest bare headland, in your neighborhood.
+
+But how can this be? If all these stratified rocks are built on the
+floor of the ocean out of material taken _from_ the land, how can we
+by any possibility find such rocks _upon_ the land? In the beds of
+rivers we might indeed expect to see them, but surely nowhere else
+save under ocean waters.
+
+Yet find them we do. Through England, through the two great
+world-continents, they abound on every side. Thousands of miles in
+unbroken succession are composed of such rocks.
+
+Stand with me near the seashore, and let us look around. Those white
+chalk cliffs--they, at least, are not formed of sand or earth. True,
+and the lines of stratification are in them very indistinct, if seen
+at all; yet they too are built up of sediment of a different kind,
+dropping upon ocean's floor. See, however, in the rough sides of
+yonder bluff the markings spoken of, fine lines running alongside of
+one another, sometimes flat, sometimes bent or slanting, but always
+giving the impression of layer piled upon layer. Yet how can one for a
+moment suppose that the ocean-waters ever rose so high?
+
+Stay a moment. Look again at yonder white chalk cliff, and observe a
+little way below the top a singular band of shingles, squeezed into
+the cliff, as it were, with chalk below and earth above.
+
+That is believed to be an old sea-beach. Once upon a time the waters
+of the sea are supposed to have washed those shingles, as now they
+wash the shore near which we stand, and all the white cliff must have
+lain then beneath the ocean.
+
+Geologists were for a long while sorely puzzled to account for these
+old sea-beaches, found high up in the cliffs around our land in many
+different places.
+
+They had at first a theory that the sea must once, in far back ages,
+have been a great deal higher than it is now. But this explanation
+only brought about fresh difficulties. It is quite impossible that the
+level of the sea should be higher in one part of the world than in
+another. If the sea around England were then one or two hundred feet
+higher than it is now, it must have been one or two hundred feet
+higher in every part of the world where the ocean-waters have free
+flow. One is rather puzzled to know where all the water could have
+come from, for such a tremendous additional amount. Besides, in some
+places remains of sea-animals are found in mountain heights, as much
+as two or three thousand feet above the sea-level--as, for instance,
+in Corsica. This very much increases the difficulty of the above
+explanation.
+
+So another theory was started instead, and this is now generally
+supposed to be the true one. What if instead of the whole ocean having
+been higher, parts of the land were lower? England at one time, parts
+of Europe at another time, parts of Asia and America at other times,
+may have slowly sunk beneath the ocean, and after long remaining there
+have slowly risen again.
+
+This is by no means so wild a supposition as it may seem when first
+heard, and as it doubtless did seem when first proposed. For even in
+the present day these movements of the solid crust of our earth are
+going on. The coasts of Sweden and Finland have long been slowly and
+steadily rising out of the sea, so that the waves can no longer reach
+so high upon those shores as in years gone by they used to reach. In
+Greenland, on the contrary, land has long been slowly and steadily
+sinking, so that what used to be the shore now lies under the sea.
+Other such risings and sinkings might be mentioned, as also many more
+in connection with volcanoes and earthquakes, which are neither slow
+nor steady, but sudden and violent.
+
+So it becomes no impossible matter to believe that, in the course of
+ages past, all those wide reaches of our continents and islands, where
+sedimentary rocks are to be found, were each in turn, at one time or
+another, during long periods, beneath the rolling waters of the
+ocean....
+
+       *       *       *       *       *
+
+These built-up rocks are not only called "Stratified," and
+"Sedimentary." They have also the name of _Aqueous Rock_, from the
+Latin word _aqua, water_; because they are believed to have been
+formed by the action of the water.
+
+They have yet another and fourth title, which is, _Fossiliferous
+Rocks_.
+
+Fossils are the hardened remains of animals and vegetables found in
+rocks. They are rarely, if ever, seen in unstratified rocks; but many
+layers of stratified rocks abound in these remains. Whole skeletons as
+well as single bones, whole tree-trunks as well as single leaves, are
+found thus embedded in rock-layers, where in ages past the animal or
+plant died and found a grave. They exist by thousands in many parts of
+the world, varying in size from the huge skeleton of the elephant to
+the tiny shell of the microscopic animalcule.
+
+[Illustration: FOSSIL OF CARBONIFEROUS FERN.]
+
+Fossils differ greatly in kind. Sometimes the entire shell or bone is
+changed into stone, losing all its animal substance, but retaining its
+old outline and its natural markings. Sometimes the fossil is merely
+the hardened impress of the outside of a shell or leaf, which has
+dented its picture on soft clay, and has itself disappeared, while the
+soft clay has become rock, and the indented picture remains fixed
+through after-centuries. Sometimes the fossil is the cast of the
+inside of a shell; the said shell having been filled with soft mud,
+which has taken its exact shape and hardened, while the shell itself
+has vanished. The most complete description of fossil is the first of
+these three kinds. It is wonderfully shown sometimes in fossil wood,
+where all the tiny cells and delicate fibres remain distinctly marked
+as of old, only the whole woody substance has changed into hard stone.
+
+[Illustration: FOOTPRINTS FROM TRIASSIC SANDSTONE OF CONNECTICUT.]
+
+But although the fossil remains of quadrupeds and other land-animals
+are found in large quantities, their number is small compared with the
+enormous number of fossil sea-shells and sea-animals.
+
+[Illustration: FOSSIL FOOTPRINTS.]
+
+Land-animals can, as a rule, have been so preserved, only when they
+have been drowned in ponds or rivers, or mired in bogs and swamps, or
+overtaken by frost, or swept out to sea.
+
+Sea-animals, on the contrary, have been so preserved on land whenever
+that land has been under the sea; and this appears to have been the
+case, at one or another past age, with the greater part of our
+present continents. These fossil remains of sea-animals are
+discovered in all quarters of the world, not only on the seashore but
+also far inland, not only deep down underground but also high up on
+the tops of lofty mountains--a plain proof that over the summits of
+those mountains the ocean must once have rolled, and this not for a
+brief space only, but through long periods of time. And not on the
+mountain-summit only are these fossils known to abound, but sometimes
+in layer below layer of the mountain, from top to bottom, through
+thousands of feet of rock.
+
+[Illustration: FOSSIL SHELLS.]
+
+This may well seem puzzling at first sight. Fossils of sea-creatures
+on a mountain-top are startling enough; yet hardly so startling as the
+thought of fossils _inside_ that mountain. How could they have found
+their way thither?
+
+The difficulty soon vanishes, if once we clearly understand that all
+these thousands of feet of rock were built up slowly, layer after
+layer, when portions of the land lay deep under the sea. Thus _each
+separate layer_ of mud or sand or other material became in its turn
+the _top layer_, and was for the time the floor of the ocean, until
+further droppings of material out of the waters made a fresh layer,
+covering up the one below.
+
+While each layer was thus in succession the top layer of the building,
+and at the same time the floor of the ocean, animals lived and died
+in the ocean, and their remains sank to the bottom, resting upon the
+sediment floor. Thousands of such dead remains disappeared, crumbling
+into fine dust and mingling with the waters, but here and there one
+was caught captive by the half-liquid mud, and was quickly covered and
+preserved from decay. And still the building went on, and still layer
+after layer was placed, till many fossils lay deep down beneath the
+later-formed layers; and when at length, by slow or quick upheaval of
+the ground, this sea-bottom became a mountain, the little fossils were
+buried within the body of that mountain. So wondrously the matter
+appears to have come about.
+
+       *       *       *       *       *
+
+Another difficulty with respect to the stratified rocks has to be
+thought of. All these layers or deposits of gravel, sand, or earth, on
+the floor of the ocean, would naturally be horizontal--that is, would
+lie flat, one upon another. In places the ocean-floor might slant, or
+a crevice or valley or ridge might break the smoothness of the
+deposit. But though the layers might partake of the slant, though the
+valley might have to be filled, though the ridge might have to be
+surmounted, still the general tendency of the waves would be to level
+the dropping deposits into flat layers.
+
+Then how is it that when we examine the strata of rocks in our
+neighborhood, wherever that neighborhood may be, we do not find them
+so arranged? Here, it is true, the lines for a space are nearly
+horizontal, but there, a little way farther on, they are
+perpendicular; here they are bent, and there curved; here they are
+slanting, and there crushed and broken.
+
+This only bears out what has been already said about the Book of
+Geology. It _has_ been bent and disturbed, crushed and broken.
+
+Great powers have been at work in this crust of our earth. Continents
+have been raised, mountains have been upheaved, vast masses of rock
+have been scattered into fragments. Here or there we may find the
+layers arranged as they were first laid down; but far more often we
+discover signs of later disturbance, either slow or sudden, varying
+from a mere quiet tilting to a violent overturn.
+
+[Illustration: EXAMPLE OF DISTURBANCE OF THE EARTH'S LAYERS.]
+
+So the Book of Geology is a torn and disorganized volume, not easy to
+read.
+
+Yet, on the other hand, these very changes which have taken place are
+a help to the geologist.
+
+It may seem at first sight as if we should have an easier task, if the
+strata were all left lying just as they were first formed, in smooth
+level layers, one above another. But if it were so, we could know very
+little about the lower layers.
+
+We might indeed feel sure, as we do now, that the lowest layers were
+the oldest and the top layers the newest, and that any fossils found
+in the lower layers must belong to an age farther back than any
+fossils found in the upper layers.
+
+So much would be clear. And we might dig also and burrow a little way
+down, through a few different kinds of rock, where they were not too
+thick. But that would be all. There our powers would cease.
+
+Now how different. Through the heavings and tiltings of the earth's
+crust, the lower layers are often pushed quite up to the surface, so
+that we are able to examine them and their fossils without the least
+difficulty, and very often without digging underground at all.
+
+You must not suppose that the real order of the rocks is changed by
+these movements, for generally speaking it is not. The lower kinds are
+rarely if ever found placed _over_ the upper kinds; only the ends of
+them are seen peeping out above ground.
+
+It is as if you had a pile of copy-books lying flat one upon another,
+and were to put your finger under the lowest and push it up. All those
+above would be pushed up also, and perhaps they would slip a little
+way down, so that you would have a row of _edges_ showing side by
+side, at very much the same height. The arrangement of the copy-books
+would not be changed, for the lowest would still be the lowest in
+actual position; but a general tilting or upheaval would have taken
+place.
+
+Just such a tilting or upheaval has taken place again and again with
+the rocks forming our earth-crust. The edges of the lower rocks often
+show side by side with those of higher layers.
+
+But geologists know them apart. They are able to tell confidently
+whether such and such a rock, peeping out at the earth's surface,
+belongs really to a lower or a higher kind. For there is a certain
+sort of order followed in the arrangement of rock-layers all over the
+earth, and it is well known that some rocks are never found below some
+other rocks, that certain particular kinds are never placed above
+certain other kinds. Thus it follows that the fossils found in one
+description of rock, must be the fossils of animals which lived and
+died before the animals whose fossil remains are found in another
+neighboring rock, just because this last rock-layer was built upon the
+ocean-floor above and therefore later than the other.
+
+All this is part of the foreign language of geology--part of the
+piecing and arranging of the torn volume. Many mistakes are made; many
+blunders are possible; but the mistakes and blunders are being
+gradually corrected, and certain rules by which to read and understand
+are becoming more and more clear.
+
+It has been already said that unstratified rocks are those which have
+been at some period, whether lately or very long ago, in a liquid
+state from intense heat, and which have since cooled, either quickly
+or slowly, crystallizing as they cooled.
+
+Unstratified Rocks may be divided into two distinct classes.
+
+[Illustration: SECTION OF A LAVA BOMB.]
+
+First.--Volcanic Rocks, such as lava. These have been quickly cooled
+at the surface of the earth, or not far below it.
+
+Secondly.--Plutonic Rocks, such as granite. These have been slowly
+cooled deep down in the earth under heavy pressure.
+
+There is also a class of rocks, called metamorphic rocks, including
+some kinds of marble. These are, strictly speaking, crystalline rocks,
+and yet they are arranged in something like layers. The word
+"metamorphic" simply means "transformed." They are believed to have
+been once stratified rocks, perhaps containing often the remains of
+animals; but intense heat has later transformed them into crystalline
+rocks, and the animal remains have almost or quite vanished.
+
+[Illustration: LAVA-STREAM ON VESUVIUS.]
+
+Just as the different kinds of Stratified Rocks are often called
+Aqueous Rocks, or rocks formed by the action of water--so these
+different kinds of Unstratified Rocks are often called Igneous Rocks,
+or rocks formed by the action of fire--the name being taken from the
+Latin word for fire. The Metamorphic Rocks are sometimes described as
+"Aqueo-igneous," since both water and fire helped in the forming of
+them.
+
+It was at one time believed, as a matter of certainty, that granite
+and such rocks belonged to a period much farther back than the periods
+of the stratified rocks. That is to say, it was supposed that
+fire-action had come first and water-action second; that the fire-made
+rocks were all formed in very early ages, and that only water-made
+rocks still continued to be formed. So the name of Primary Rocks, or
+First Rocks, was given to the granites and other such rocks, and the
+name of Secondary Rocks to all water-built rocks; while those of the
+third class were called Transition Rocks, because they seemed to be a
+kind of link or stepping-stone in the change from the First to the
+Second Rocks.
+
+The chief reason for the general belief that fire-built rocks were
+older than water-built ones was, that the former are as a rule found
+to lie _lower_ than the latter. They form, as it were, the basement of
+the building, while the top-stories are made of water-built rocks.
+
+Many still believe that there is much truth in the thought. It is most
+probable, so far as we are able to judge, that the _first-formed_
+crust of rocks all over the earth was of cooled and crystallized
+material. As these rocks were crumbled and wasted by the ocean,
+materials would have been supplied for the building-up of rocks, layer
+upon layer.
+
+But this is conjecture. We cannot know with any certainty the course
+of events so far back in the past. And geologists are now able to
+state with tolerable confidence that, however old many of the granites
+may be, yet a large amount of the fire-built rocks are no older than
+the water-built rocks which lie over them.
+
+So by many geologists the names of Primary, Transition, and Secondary
+Formations are pretty well given up. It has been proposed to give
+instead to the crystallized rocks of all kinds the name of Underlying
+Rocks (Hypogene Rocks).
+
+But if they really do lie under, how can they possibly be of the same
+age? One would scarcely venture to suppose, in looking at a building,
+that the cellars had not been finished before the upper floors.
+
+True. In the first instance doubtless the cellars were first made,
+then the ground-floor, then the upper stories.
+
+When, however, the house was so built, alterations and improvements
+might be very widely carried on above and below. While one set of
+workmen were engaged in remodelling the roof, another set of workmen
+might be engaged in remodelling the kitchens and first floor, pulling
+down, propping up, and actually rebuilding parts of the lower walls.
+
+This is precisely what the two great fellow-workmen, Fire and Water,
+are ever doing in the crust of our earth. And if it be objected that
+such alterations too widely undertaken might result in slips, cracks,
+and slidings, of ceilings and walls in the upper stories, I can only
+say that such catastrophes _have_ been the result of underground
+alterations in that great building, the earth's crust....
+
+We see therefore clearly that, although the earliest fire-made rocks
+may very likely date farther back than the earliest water-made rocks,
+yet the making of the two kinds has gone on side by side, one below
+and the other above ground, through all ages up to the present moment.
+
+And just as in the present day water continues its busy work above
+ground of pulling down and building up, so also fire continues its
+busy work underground of melting rocks which afterwards cool into new
+forms, and also of shattering and upheaving parts of the earth-crust.
+
+For there can be no doubt that fiery heat does exist as a mighty power
+within our earth, though to what extent we are not able to say.
+
+These two fellow-workers in nature have different modes of working.
+One we can see on all sides, quietly progressing, demolishing land
+patiently bit by bit, building up land steadily grain by grain. The
+other, though more commonly hidden from sight, is fierce and
+tumultuous in character, and shows his power in occasional terrific
+outbursts.
+
+We can scarcely realize what the power is of the imprisoned fiery
+forces underground, though even we are not without some witness of
+their existence. From time to time even our firm land has been felt to
+tremble with a thrill from some far-off shock; and even in our country
+is seen the marvel of scalding water pouring unceasingly from deep
+underground....
+
+Think of the tremendous eruptions of Vesuvius, of Etna, of Hecla, of
+Mauna Loa. Think of whole towns crushed and buried, with their
+thousands of living inhabitants. Think of rivers of glowing lava
+streaming up from regions below ground, and pouring along the surface
+for a distance of forty, fifty, and even sixty miles, as in Iceland
+and Hawaii. Think of red-hot cinders flung from a volcano-crater to a
+height of ten thousand feet. Think of lakes of liquid fire in other
+craters, five hundred to a thousand feet across, huge cauldrons of
+boiling rock. Think of showers of ashes from the furnace below of yet
+another, borne so high aloft as to be carried seven hundred miles
+before they sank to earth again. Think of millions of red-hot stones
+flung out in one eruption of Vesuvius. Think of a mass of rock, one
+hundred cubic yards in size, hurled to a distance of eight miles or
+more out of the crater of Cotopaxi.
+
+[Illustration: HOT WELLS.]
+
+Think also of earthquake-shocks felt through twelve hundred miles of
+country. Think of fierce tremblings and heavings lasting in constant
+succession through days and weeks of terror. Think of hundreds of
+miles of land raised several feet in one great upheaval. Think of the
+earth opening in scores of wide-lipped cracks, to swallow men and
+beasts. Think of hot mud, boiling water, scalding stream, liquid rock,
+bursting from such cracks, or pouring from rents in a mountain-side.
+
+Truly these are signs of a state of things in or below the solid crust
+on which we live, that may make us doubt the absolute security of
+"Mother Earth."
+
+Different explanations have been put forward to explain this seemingly
+fiery state of things underground.
+
+Until lately the belief was widely held that our earth was one huge
+globe of liquid fire, with only a slender cooled crust covering her, a
+few miles in thickness.
+
+This view was supported by the fact that heat is found to increase as
+men descend into the earth. Measurements of such heat-increase have
+been taken, both in mines and in borings for wells. The usual rate is
+about one degree more of heat, of our common thermometer, for every
+fifty or sixty feet of descent. If this were steadily continued, water
+would boil at a depth of eight thousand feet below the surface; iron
+would melt at a depth of twenty-eight miles; while at a depth of forty
+or fifty miles no known substance upon earth could remain solid.
+
+The force of this proof is, however, weakened by the fact that the
+rate at which the heat increases differs very much in different
+places. Also it is now generally supposed that such a tremendous
+furnace of heat--a furnace nearly eight thousand miles in
+diameter--could not fail to break up and melt so slight a covering
+shell.
+
+Many believe, therefore, not that the whole interior of the earth is
+liquid with heat, but that enormous fire-seas or lakes of melted rock
+exist here and there, under or in the earth-crust. From these lakes
+the volcanoes would be fed, and they would be the cause of earthquakes
+and land-upheavals or land-sinkings. There are strong reasons for
+supposing that the earth was once a fiery liquid body, and that she
+has slowly cooled through long ages. Some hold that her centre
+probably grew solid first from tremendous pressure; that her crust
+afterwards became gradually cold; and that between the solid crust and
+the solid inside or "nucleus," a sea of melted rock long existed, the
+remains of which are still to be found in these tremendous fiery
+reservoirs.
+
+The idea accords well with the fact that large numbers of extinct or
+dead volcanoes are scattered through many parts of the earth. If the
+above explanation be the right one, doubtless the fire-seas in the
+crust extended once upon a time beneath such volcanoes, but have since
+died out or smouldered low in those parts.
+
+A somewhat curious calculation has been made, to illustrate the
+different modes of working of these two mighty powers--Fire and Water.
+
+The amount of land swept away each year in mud, and borne to the ocean
+by the River Ganges, was roughly reckoned, and also the amount of land
+believed to have been upheaved several feet in the great Chilian
+earthquake.
+
+It was found that the river, steadily working month by month, would
+require some four hundred years to carry to the sea the same weight of
+material, which in one tremendous effort was upheaved by the fiery
+underground forces.
+
+Yet we must not carry this distinction too far. Fire does not always
+work suddenly, or water slowly; witness the slow rising and sinking of
+land in parts of the earth, continuing through centuries; and witness
+also the effects of great floods and storms.
+
+The crust of the earth is made of rock. But what is rock made of?
+
+Certain leading divisions of rocks have been already considered:
+
+The Water-made Rocks;
+
+The Fire-made Rocks, both Plutonic and Volcanic;
+
+The Water-and-Fire-made Rocks.
+
+The first of these--Water-made Rocks--may be subdivided into three
+classes. These are,--
+
+I. _Flint Rocks_; II. _Clay Rocks_; III. _Lime Rocks_.
+
+This is not a book in which it would be wise to go closely into the
+mineral nature of rocks. Two or three leading thoughts may, however,
+be given.
+
+Does it not seem strange that the hard and solid rocks should be in
+great measure formed of the same substances which form the thin
+invisible air floating around us?
+
+Yet so it is. There is a certain gas called Oxygen Gas. Without that
+gas you could not live many minutes. Banish it from the room in which
+you are sitting, and in a few minutes you will die.
+
+This gas makes up nearly one-quarter by weight of the atmosphere round
+the whole earth.
+
+The same gas plays an important part in the ocean; for more than
+three-quarters of water is _oxygen_.
+
+It plays also an important part in rocks; for about half the material
+of the entire earth's crust is oxygen.
+
+Another chief material in rocks is _silicon_. This makes up
+one-quarter of the crust, leaving only one-quarter to be accounted
+for. Silicon mixed with oxygen makes silica or quartz. There are few
+rocks which have not a large amount of quartz in them. Common flint,
+sandstones, and the sand of our shores, are made of quartz, and
+therefore belong to the first class of Silicious or Flint Rocks.
+Granites and lavas are about one-half quartz. The beautiful stones,
+amethyst, agate, chalcedony, and jasper, are all different kinds of
+quartz.
+
+Another chief material in rocks is a white metal called _aluminium_.
+United to oxygen it becomes alumina, the chief substance in clay.
+Rocks of this kind--such as clays, and also the lovely blue gem,
+sapphire--are called Argillaceous Rocks, from the Latin word for clay,
+and belong to the second class. Such rocks keep fossils well.
+
+Another is _calcium_. United to oxygen and carbonic acid, it makes
+carbonate of lime, the chief substance in limestone; so all limestones
+belong to the third class of Calcareous or Lime Rocks.
+
+Other important materials may be mentioned, such as _magnesium,
+potassium, sodium, iron, carbon, sulphur, hydrogen, chlorine,
+nitrogen_. These, with many more, not so common, make up the remaining
+quarter of the earth-crust.
+
+Carbon plays as important a part in animal and vegetable life as
+silicon in rocks. Carbon is most commonly seen in three distinct
+forms--as charcoal, as black-lead, and as the pure brilliant diamond.
+Carbon united, in a particular proportion, to oxygen, forms carbonic
+acid; and carbonic acid united, in a particular proportion, to lime,
+forms limestone.
+
+_Hydrogen_ united to oxygen forms water. Each of these two gases is
+invisible alone, but when they meet and mingle they form a liquid.
+
+_Nitrogen_ united to oxygen and to a small quantity of carbonic acid
+gas forms our atmosphere.
+
+Rocks of pure flint, pure clay, or pure lime, are rarely or never met
+with. Most rocks are made up of several different substances melted
+together.
+
+       *       *       *       *       *
+
+In the fire-built rocks no remains of animals are found, though in
+water-built rocks they abound. Water-built rocks are sometimes divided
+into two classes--those which only contain occasional animal remains,
+and those which are more or less built up of the skeletons of animals.
+
+[Illustration: AMIBA PRINCEPS, ONE OF THE MANY ORDERS OF THE RHIZOPODA
+CLASS, MAGNIFIED ONE HUNDRED TIMES.]
+
+There are some exceedingly tiny creatures inhabiting the ocean, called
+Rhizopods. They live in minute shells, the largest of which may be
+almost the size of a grain of wheat, but by far the greater number are
+invisible as shells without a microscope, and merely show as fine
+dust. The rhizopods are of different shapes, sometimes round,
+sometimes spiral, sometimes having only one cell, sometimes having
+several cells. In the latter case a separate animal lives in each
+cell. The animal is of the very simplest as well as the smallest kind.
+He has not even a mouth or a stomach but can take in food at any part
+of his body.
+
+[Illustration: RHIZOPODS (MAGNIFIED).]
+
+These rhizopods live in the oceans in enormous numbers. Tens of
+millions are ever coming into existence, living out their tiny lives,
+dying, and sinking to the bottom.
+
+There upon the ocean-floor gather their remains, a heaped-up multitude
+of minute skeletons or shells, layer forming over layer.
+
+It was long suspected that the white chalk cliffs of England were
+built up in some such manner as this through past ages. And now at
+length proof has been found, in the shape of mud dredged up from the
+ocean-bottom--mud entirely composed of countless multitudes of these
+little shells, dropping there by myriads, and becoming slowly joined
+together in one mass.
+
+Just so, it is believed, were the white chalk cliffs built--gradually
+prepared on the ocean-floor, and then slowly or suddenly upheaved, so
+as to become a part of the dry land.
+
+Think what the enormous numbers must have been of tiny living
+creatures, out of whose shells the wide reaches of white chalk cliffs
+have been made. Chalk cliffs and chalk layers extend from Ireland,
+through England and France, as far as to the Crimea. In the south of
+Russia they are said to be six hundred feet thick. Yet one cubic inch
+of chalk is calculated to hold the remains of more than one million
+rhizopods. How many countless millions upon millions must have gone to
+the whole structure! How long must the work of building up have
+lasted!
+
+[Illustration: THREE POLYPS OF CORAL.]
+
+These little shells do not always drop softly and evenly to the
+ocean-floor, to become quietly part of a mass of shells. Sometimes,
+where the ocean is shallow enough for the waves to have power below,
+or where land currents can reach, they are washed about, and thrown
+one against another, and ground into fine powder; and the fine powder
+becomes in time, through different causes, solid rock.
+
+[Illustration: CORAL POLYP.]
+
+Limestone is made in another way also. In the warm waters of the South
+Pacific Ocean there are many islands, large and small, which have
+been formed in a wonderful manner by tiny living workers. The workers
+are soft jelly-like creatures, called polyps, who labor together in
+building up great walls and masses of coral.
+
+[Illustration: CORAL ISLAND.]
+
+[Illustration: YOUNG CORAL POLYP ATTACHED TO A ROCK AND EXPANDED.]
+
+They never carry on their work above the surface of the water, for in
+the air they would die. But the waves break the coral, and heap it up
+above high-water mark, and carry earth and seeds to drop there till at
+length a small low-lying island is formed.
+
+The waves not only heap up broken coral, but they grind the coral into
+fine powder, and from this powder limestone rock is made, just as it
+is from the powdered shells of rhizopods. The material used by the
+polyps in building the coral is chiefly lime, which they have the
+power of gathering out of the water, and the fine coral-powder,
+sinking to the bottom, makes large quantities of hard limestone. Soft
+chalk is rarely, if ever, found near the coral islands.
+
+[Illustration: 1. WHITE CORAL. 2. PORTION OF A BRANCH (MAGNIFIED).]
+
+Limestones are formed in the same manner from the grinding up of other
+sea-shells and fossils, various in kind; the powder becoming gradually
+united into solid rock.
+
+There is yet another way in which limestone is made, quite different
+from all these. Sometimes streams of water have a large quantity of
+lime in them; and these as they flow will drop layers of lime which
+harden into rock. Or a lime-laden spring, making its way through the
+roof of an underground cavern, will leave all kinds of fantastic
+arrangements of limestone wherever its waters can trickle and drip.
+Such a cavern is called a "stalactite cave."
+
+       *       *       *       *       *
+
+So there are different kinds of fossil rock-making. There may be rocks
+made of other materials, with fossil simply buried in them. There may
+be rocks made entirely of fossils, which have gathered in masses as
+they sank to the sea-bottom, and have there become simply and lightly
+joined together. There may be rocks made of the ground-up powder of
+fossils, pressed into a solid substance or united by some other
+substance.
+
+Rocks are also often formed of whole fossils, or stones, or shells,
+bound into one by some natural soft sticky cement, which has gathered
+round them and afterwards grown hard, like the cement which holds
+together the stones in a wall.
+
+The tiny rhizopods (meaning root foot) which have so large a share in
+chalk and limestone making, are among the smallest and simplest known
+kinds of animal life.
+
+There are also some very minute forms of vegetable life, which exist
+in equally vast numbers, called Diatoms. For a long while they were
+believed to be living animals, like the rhizopods. Scientific men are
+now, however, pretty well agreed that they really are only vegetables
+or plants.
+
+The diatoms have each one a tiny shell or shield, not made of lime
+like the rhizopod-shells, but of flint. Some think that common flint
+may be formed of these tiny shells.
+
+Again, there is a kind of rock called Mountain Meal, which is entirely
+made up of the remains of diatoms. Examined under the microscope,
+thousands of minute flint shields of various shapes are seen. This
+rock, or earth, is very abundant in many places, and is sometimes used
+as a polishing powder. In Bohemia there is a layer of it no less than
+fourteen feet thick. Yet so minute are the shells of which it is
+composed, that one square inch of rock is said to contain about four
+thousand millions of them. Each one of these millions is a separate
+distinct fossil....
+
+       *       *       *       *       *
+
+[Illustration: SUCCESSION OF BURIED COAL-GROWTHS AND ERECT
+TREE-STUMPS. SYDNEY, CAPE BRETON.
+
+_a._ Sandstone, _b._ Shales, _c._ Coal-seams, _d._ Bed containing
+Roots and Stumps _in situ_.]
+
+If you examine carefully a piece of coal, you will find, more or less
+clearly, markings like those which are seen in a piece of wood.
+Sometimes they are very distinct indeed. Coal abounds in impressions
+of leaves, ferns, and stems, and fossil remains of plants and
+tree-trunks are found in numbers in coal-seams.
+
+Coal is a vegetable substance. The wide coal-fields of Britain and
+other lands are the _fossil_ remains of vast forests.
+
+Long ages ago, as it seems, broad and luxuriant forests flourished
+over the earth. In many parts generation after generation of trees
+lived and died and decayed, leaving no trace of their existence,
+beyond a little layer of black mould, soon to be carried away by wind
+and water. Coal could only be formed where there were bogs and
+quagmires.
+
+But in bogs and quagmires, and in shallow lakes of low-lying lands,
+there were great gatherings of slowly-decaying vegetable remains,
+trees, plants, and ferns all mingling together. Then after a while the
+low lands would sink and the ocean pouring in would cover them with
+layers of protecting sand or mud; and sometimes the land would rise
+again, and fresh forests would spring into life, only to be in their
+turn overwhelmed anew, and covered by fresh sandy or earthy deposits.
+
+These buried forests lay through the ages following, slowly hardening
+into the black and shining coal, so useful now to man.
+
+The coal is found thus in thin or thick seams, with other rock-layers
+between, telling each its history of centuries long past. In one place
+no less than sixteen such beds of coal are found, one below another,
+each divided from the next above and the next underneath by beds of
+clay or sand or shale. The forests could not have grown in the sea,
+and the earth-layers could not have been formed on land, therefore
+many land-risings and sinkings must have taken place. Each bed
+probably tells the tale of a succession of forests....
+
+       *       *       *       *       *
+
+Before going on to a sketch of the early ages of the Earth's
+history--ages stretching back long long before the time of Adam--it is
+needful to think yet for a little longer about the manner in which
+that history is written, and the way in which it has to be read.
+
+For the record is one difficult to make out, and its style of
+expression is often dark and mysterious. There is scarcely any other
+volume in the great Book of Nature, which the student is so likely to
+misread as this one. It is very needful, therefore, to hold the
+conclusions of geologists with a light grasp, guarding each with a
+"perhaps" or a "may be." Many an imposing edifice has been built, in
+geology, upon a rickety foundation which has speedily given way.
+
+In all ages of the world's history up to the present day, rock-making
+has taken place--fire-made rocks being fashioned underground, and
+water-made rocks being fashioned above ground though under water.
+
+Also in all ages different kinds of rocks have been fashioned side by
+side--limestone in one part of the world, sandstone in another, chalk
+in another, clay in another, and so on. There have, it is true, been
+ages when one kind seems to have been the _chief_ kind--an age of
+limestone, or an age of chalk. But even then there were doubtless more
+rock-buildings going on, though not to so great an extent. On the
+other hand, there may have been ages during which no limestone was
+made, or no chalk, or no clay. As a general rule, however, the various
+sorts of rock-building have probably gone on together. This was not so
+well understood by early geologists as it is now.
+
+The difficulty is often great of disentangling the different strata,
+and saying which was earlier and which later formed.
+
+Still, by close and careful study of the rocks which compose the
+earth's crust, a certain kind of order is found to exist, more or less
+followed out in all parts of the world. _When_ each layer was formed
+in England or in America, the geologist cannot possibly say. He can,
+however, assert, in either place, that a certain mass of rock was
+formed before a certain other mass in that same place, even though
+the two may seem to lie side by side; for he knows that they were so
+placed only by upheaval, and that once upon a time the one lay beneath
+the other.
+
+The geologist can go further. He can often declare that a certain mass
+of rock in America and a certain mass of rock in England, quite
+different in kind, were probably built up at about the same time. How
+long ago that time was he would be rash to attempt to say; but that
+the two belong to the same age he has good reason for supposing.
+
+We find rocks piled upon rocks in a certain order, so that we may
+generally be pretty confident that the lower rocks were first made,
+and the upper rocks the latest built. Further than this, we find in
+all the said layers of water-built rocks signs of past life.
+
+As already stated, much of this life was ocean-life, though not all.
+
+Below the sea, as the rock-layers were being formed, bit by bit, of
+earth dropping from the ocean to the ocean's floor, sea-creatures
+lived out their lives and died by thousands, to sink to that same
+floor. Millions passed away, dissolving and leaving no trace behind;
+but thousands were preserved--shells often, animals sometimes.
+
+Nor was this all. For now and again some part of the sea-bottom was
+upheaved, slowly or quickly, till it became dry land. On this dry land
+animals lived again, and thousands of them, too, died, and their bones
+crumbled into dust. But here and there one was caught in bog or frost,
+and his remains were preserved till, through lapse of ages, they
+turned to stone.
+
+Yet again that land would sink, and over it fresh layers were formed
+by the ocean-waters, with fresh remains of sea-animals buried in with
+the layers of sand or lime; and once more the sea-bottom would rise,
+perhaps then to continue as dry land, until the day when man should
+discover and handle these hidden remains.
+
+Now note a remarkable fact as to these fossils, scattered far and wide
+through the layers of stratified rock.
+
+In the uppermost and latest built rocks the animals found are the
+same, in great measure, as those which now exist upon the earth.
+
+Leaving the uppermost rocks, and examining those which lie a little
+way below, we find a difference. Some are still the same, and others,
+if not quite the same, are very much like what we have now; but here
+and there a creature of a different form appears.
+
+Go deeper still, and the kinds of animals change further. Fewer and
+fewer resemble those which now range the earth; more and more belong
+to other species.
+
+Descend through layer after layer till we come to rocks built in
+earliest ages and not one fossil shall we find precisely the same as
+one animal living now.
+
+So not only are the rocks built in successive order, stratum after
+stratum belonging to age after age in the past, but fossil-remains
+also are found in successive order, kind after kind belonging to past
+age after age.
+
+Although in the first instance the succession of fossils was
+understood by means of the succession of rock-layers, yet in the
+second place the arrangement of rock-layers is made more clear by the
+means of these very fossils.
+
+A geologist, looking at the rocks in America, can say which there were
+first-formed, which second-formed, which third-formed. Also, looking
+at the rocks in England, he can say which there were first-formed,
+second-formed, third-formed. He would, however, find it very
+difficult, if not impossible, to say which among any of the American
+rocks was formed at about the same time as any particular one among
+the English rocks, were it not for the help afforded him by these
+fossils.
+
+Just as the regular succession of rock-strata has been gradually
+learned, so the regular succession of different fossils is becoming
+more and more understood. It is now known that some kinds of fossils
+are always found in the oldest rocks, and in them only; that some
+kinds are always found in the newest rocks, and in them only; that
+some fossils are rarely or never found lower than certain layers; that
+some fossils are rarely or never found higher than certain other
+layers.
+
+So this fossil arrangement is growing into quite a history of the
+past. And a geologist, looking at certain rocks, pushed up from
+underground, in England and in America, can say: "These are very
+different kinds of rocks, it is true, and it would be impossible to
+say how long the building up of the one might have taken place before
+or after the other. But I see that in both these rocks there are
+exactly the same kinds of fossil-remains, differing from those in the
+rocks above and below. I conclude therefore that the two rocks belong
+to about the same great age in the world's past history, when the
+same animals were living upon the earth."
+
+Observing and reasoning thus, geologists have drawn up a general plan
+or order of strata; and the whole of the vast masses of water-built
+rocks throughout the world have been arranged in a regular succession
+of classes, rising step by step from earliest ages up to the present
+time.
+
+[Illustration]
+
+
+
+
+AMERICA THE OLD WORLD
+
+(FROM GEOLOGICAL SKETCHES.)
+
+BY L. AGASSIZ.
+
+
+[Illustration]
+
+First-born among the Continents, though so much later in culture and
+civilization than some of more recent birth, America, so far as her
+physical history is concerned, has been falsely denominated the _New
+World_. Hers was the first dry land lifted out of the waters, hers the
+first shore washed by the ocean that enveloped all the earth beside;
+and while Europe was represented only by islands rising here and there
+above the sea, America already stretched an unbroken line of land from
+Nova Scotia to the Far West.
+
+In the present state of our knowledge, our conclusions respecting the
+beginning of the earth's history, the way in which it took form and
+shape as a distinct, separate planet, must, of course, be very vague
+and hypothetical. Yet the progress of science is so rapidly
+reconstructing the past that we may hope to solve even this problem;
+and to one who looks upon man's appearance upon the earth as the
+crowning work in a succession of creative acts, all of which have had
+relation to his coming in the end, it will not seem strange that he
+should at last be allowed to understand a history which was but the
+introduction to his own existence. It is my belief that not only the
+future, but the past also, is the inheritance of man, and that we
+shall yet conquer our lost birthright.
+
+Even now our knowledge carries us far enough to warrant the assertion
+that there was a time when our earth was in a state of igneous fusion,
+when no ocean bathed it and no atmosphere surrounded it, when no wind
+blew over it and no rain fell upon it, but an intense heat held all
+its materials in solution. In those days the rocks which are now the
+very bones and sinews of our mother Earth--her granites, her
+porphyries, her basalts, her syenites--were melted into a liquid mass.
+As I am writing for the unscientific reader, who may not be familiar
+with the facts through which these inferences have been reached, I
+will answer here a question which, were we talking together, he might
+naturally ask in a somewhat sceptical tone. How do you know that this
+state of things ever existed, and, supposing that the solid materials
+of which our earth consists were ever in a liquid condition, what
+right have you to infer that this condition was caused by the action
+of heat upon them? I answer, Because it is acting upon them still;
+because the earth we tread is but a thin crust floating on a liquid
+sea of molten materials; because the agencies that were at work then
+are at work now, and the present is the logical sequence of the past.
+From artesian wells, from mines, from geysers, from hot springs, a
+mass of facts has been collected, proving incontestably the heated
+condition of all substances at a certain depth below the earth's
+surface; and if we need more positive evidence, we have it in the
+fiery eruptions that even now bear fearful testimony to the molten
+ocean seething within the globe and forcing its way but from time to
+time. The modern progress of Geology has led us by successive and
+perfectly connected steps back to a time when what is now only an
+occasional and rare phenomenon was the normal condition of our earth;
+when the internal fires were enclosed by an envelope so thin that it
+opposed but little resistance to their frequent outbreak, and they
+constantly forced themselves through this crust, pouring out melted
+materials that subsequently cooled and consolidated on its surface. So
+constant were these eruptions, and so slight was the resistance they
+encountered, that some portions of the earlier rock-deposits are
+perforated with numerous chimneys, narrow tunnels as it were, bored by
+the liquid masses that poured out through them and greatly modified
+their first condition.
+
+[Illustration: IDEAL SECTION OF A VOLCANO IN ACTION.]
+
+The question at once suggests itself, How was even this thin crust
+formed? what should cause any solid envelope, however slight and filmy
+when compared to the whole bulk of the globe, to form upon the surface
+of such a liquid mass? At this point of the investigation the
+geologist must appeal to the astronomer; for in this vague and
+nebulous border-land, where the very rocks lose their outlines and
+flow into each other, not yet specialized into definite forms and
+substances,--there the two sciences meet. Astronomy shows us our
+planet thrown off from the central mass of which it once formed a
+part, to move henceforth in an independent orbit of its own. That
+orbit, it tells us, passed through celestial spaces cold enough to
+chill this heated globe, and of course to consolidate it externally.
+We know, from the action of similar causes on a smaller scale and on
+comparatively insignificant objects immediately about us, what must
+have been the effect of this cooling process upon the heated mass of
+the globe. All substances when heated occupy more space than they do
+when cold. Water, which expands when freezing, is the only exception
+to this rule. The first effect of cooling the surface of our planet
+must have been to solidify it, and thus to form a film or crust over
+it. That crust would shrink as the cooling process went on; in
+consequence of the shrinking, wrinkles and folds would arise upon it,
+and here and there, where the tension was too great, cracks and
+fissures would be produced. In proportion as the surface cooled, the
+masses within would be affected by the change of temperature
+outside of them, and would consolidate internally also, the crust
+gradually thickening by this process.
+
+[Illustration: A VOLCANO.]
+
+But there was another element without the globe, equally powerful in
+building it up. Fire and water wrought together in this work, if not
+always harmoniously, at least with equal force and persistency. I have
+said that there was a time when no atmosphere surrounded the earth;
+but one of the first results of the cooling of its crust must have
+been the formation of an atmosphere, with all the phenomena connected
+with it,--the rising of vapors, their condensation into clouds, the
+falling of rains, the gathering of waters upon its surface. Water is a
+very active agent of destruction, but it works over again the
+materials it pulls down or wears away, and builds them up anew in
+other forms. As soon as an ocean washed over the consolidated crust of
+the globe, it would begin to abrade the surfaces upon which it moved,
+gradually loosening and detaching materials, to deposit them again as
+sand or mud or pebbles at its bottom in successive layers, one above
+another. Thus, in analyzing the crust of the globe, we find at once
+two kinds of rocks, the respective work of fire and water: the first
+poured out from the furnaces within, and cooling, as one may see any
+mass of metal cool that is poured out from a smelting-furnace to-day,
+in solid crystalline masses, without any division into separate layers
+or leaves; and the latter in successive beds, one over another, the
+heavier materials below, the lighter above, or sometimes in alternate
+layers, as special causes may have determined successive deposits of
+lighter or heavier materials at some given spot.
+
+There were many well-fought battles between geologists before it was
+understood that these two elements had been equally active in building
+up the crust of the earth. The ground was hotly contested by the
+disciples of the two geological schools, one of which held that the
+solid envelope of the earth was exclusively due to the influence of
+fire, while the other insisted that it had been accumulated wholly
+under the agency of water. This difference of opinion grew up very
+naturally; for the great leaders of the two schools lived in different
+localities, and pursued their investigations over regions where the
+geological phenomena were of an entirely opposite character,--the one
+exhibiting the effect of volcanic eruptions, the other that of
+stratified deposits. It was the old story of the two knights on
+opposite sides of the shield, one swearing that it was made of gold,
+the other that it was made of silver; and almost killing each other
+before they discovered that it was made of both. So prone are men to
+hug their theories and shut their eyes to any antagonistic facts, that
+it is related of Werner, the great leader of the Aqueous school, that
+he was actually on his way to see a geological locality of especial
+interest, but, being told that it confirmed the views of his
+opponents, he turned round and went home again, refusing to see what
+might force him to change his opinions. If the rocks did not confirm
+his theory, so much the worse for the rocks,--he would none of them.
+At last it was found that the two great chemists, fire and water, had
+worked together in the vast laboratory of the globe, and since then
+scientific men have decided to work together also; and if they still
+have a passage at arms occasionally over some doubtful point, yet the
+results of their investigations are ever drawing them nearer to each
+other,--since men who study truth, when they reach their goal, must
+always meet at last on common ground.
+
+The rocks formed under the influence of heat are called, in geological
+language, the Igneous, or, as some naturalists have named them, the
+Plutonic rocks, alluding to their fiery origin, while the others have
+been called Aqueous or Neptunic rocks, in reference to their origin
+under the agency of water. A simpler term, however, quite as
+distinctive, and more descriptive of their structure, is that of the
+stratified and massive or unstratified rocks. We shall see hereafter
+how the relative position of these two classes of rocks and their
+action upon each other enable us to determine the chronology of the
+earth, to compare the age of her mountains, and, if we have no
+standard by which to estimate the positive duration of her continents,
+to say at least which was the first-born among them, and how their
+characteristic features have been successfully worked out. I am aware
+that many of these inferences, drawn from what is called "the
+geological record," must seem to be the work of the imagination. In a
+certain sense this is true,--for imagination, chastened by correct
+observation, is our best guide in the study of Nature. We are too apt
+to associate the exercise of this faculty with works of fiction, while
+it is in fact the keenest detective of truth.
+
+[Illustration: DIKES.]
+
+Besides the stratified and massive rocks, there is still a third set,
+produced by the contact of these two, and called, in consequence of
+the changes thus brought about, the Metamorphic rocks. The effect of
+heat upon clay is to bake it into slate; limestone under the influence
+of heat becomes quick-lime, or, if subjected afterwards to the action
+of water, it is changed to mortar; sand under the same agency is
+changed to a coarse kind of glass. Suppose, then, that a volcanic
+eruption takes place in a region of the earth's surface where
+successive layers of limestone, of clay, and of sandstone, have been
+previously deposited by the action of water. If such an eruption has
+force enough to break through these beds, the hot, melted masses will
+pour out through the rent, flow over its edges, and fill all the
+lesser cracks and fissures produced by such a disturbance. What will
+be the effect upon the stratified rocks? Wherever these liquid masses,
+melted by a heat more intense than can be produced by any artificial
+means, have flowed over them or cooled in immediate contact with them,
+the clays will be changed to slate, the limestone will have assumed a
+character more like marble, while the sandstone will be vitrified.
+This is exactly what has been found to be the case, wherever the
+stratified rocks have been penetrated by the melted masses from
+beneath. They have been themselves partially melted by the contact,
+and when they have cooled again, their stratification, though still
+perceptible, has been partly obliterated, and their substance changed.
+Such effects may often be traced in dikes, which are only the cracks
+in rocks filled by materials poured into them at some period of
+eruption when the melted masses within the earth were thrown out and
+flowed like water into any inequality or depression of the surface
+around. The walls enclosing such a dike are often found to be
+completely altered by contact with its burning contents, and to have
+assumed a character quite different from the rocks of which they make
+a part; while the mass itself which fills the fissure shows by the
+character of its crystallization that it has cooled more quickly on
+the outside, where it meets the walls, than at the centre.
+
+The first two great classes of rocks, the unstratified and stratified
+rocks, represent different epochs in the world's physical history: the
+former mark its revolutions, while the latter chronicle its periods of
+rest. All mountains and mountain-chains have been upheaved by great
+convulsions of the globe, which rent asunder the surface of the earth,
+destroyed the animals and plants living upon it at the time, and were
+then succeeded by long intervals of repose, when all things returned
+to their accustomed order, ocean and river deposited fresh beds in
+uninterrupted succession, the accumulation of materials went on as
+before, a new set of animals and plants were introduced, and a time of
+building up and renewing followed the time of destruction. These
+periods of revolution are naturally more difficult to decipher than
+the periods of rest; for they have so torn and shattered the beds they
+uplifted, disturbing them from their natural relations to each other,
+that it is not easy to reconstruct the parts and give them coherence
+and completeness again. But within the last half-century this work has
+been accomplished in many parts of the world with an amazing degree of
+accuracy, considering the disconnected character of the phenomena to
+be studied; and I think I shall be able to convince my readers that
+the modern results of geological investigation are perfectly sound
+logical inferences from well-established facts. In this, as in so many
+other things, we are but "children of a larger growth." The world is
+the geologist's great puzzle-box; he stands before it like the child
+to whom the separate pieces of his puzzle remain a mystery till he
+detects their relation and sees where they fit, and then his fragments
+grow at once into a connected picture beneath his hand....
+
+When geologists first turned their attention to the physical history
+of the earth, they saw at once certain great features which they took
+to be the skeleton and basis of the whole structure. They saw the
+great masses of granite forming the mountains and mountain-chains,
+with the stratified rocks resting against their slopes; and they
+assumed that granite was the first primary agent, and that all
+stratified rocks must be of a later formation. Although this involved
+a partial error, as we shall see hereafter when we trace the upheavals
+of granite even into comparatively modern periods, yet it held an
+important geological truth also; for, though granite formations are by
+no means limited to those early periods, they are nevertheless very
+characteristic of them, and are indeed the foundation-stones on which
+the physical history of the globe is built.
+
+Starting from this landmark, the earlier geologists divided the
+world's history into three periods. As the historian recognizes
+Ancient History, the Middle Ages, and Modern History as distinct
+phases in the growth of the human race, so they distinguished between
+what they called the Primary period, when, as they believed, no life
+stirred on the surface of the earth; the Secondary or middle period,
+when animals and plants were introduced, and the land began to assume
+continental proportions; and the Tertiary period, or comparatively
+modern geological times, when the physical features of the earth as
+well as its inhabitants were approaching more nearly to the present
+condition of things. But as their investigations proceeded, they found
+that every one of these great ages of the world's history was divided
+into numerous lesser epochs, each of which had been characterized by a
+peculiar set of animals and plants, and had been closed by some great
+physical convulsion, disturbing and displacing the materials
+accumulated during such a period of rest.
+
+The further study of these subordinate periods showed that what had
+been called Primary formations, namely, the volcanic or Plutonic rocks
+formerly believed to be confined to the first geological ages,
+belonged to all the periods, successive eruptions having taken place
+at all times, pouring up through the accumulated deposits, penetrating
+and injecting their cracks, fissures, and inequalities, as well as
+throwing out large masses on the surface. Up to our own day there has
+never been a period when such eruptions have not taken place, though
+they have been constantly diminishing in frequency and extent. In
+consequence of this discovery, that rocks of igneous character were by
+no means exclusively characteristic of the earliest times, they are
+now classified together upon very different grounds from those on
+which geologists first united them; though, as the name _Primary_ was
+long retained, we still find it applied to them, even in geological
+works of quite recent date. This defect of nomenclature is to be
+regretted, as likely to mislead the student, because it seems to refer
+to time; whereas it no longer signifies the age of the rocks, but
+simply their character. The name Plutonic or Massive rocks is,
+however, now almost universally substituted for that of Primary.
+
+A wide field of investigation still remains to be explored by the
+chemist and the geologist together, in the mineralogical character of
+the Plutonic rocks, which differs greatly in the different periods.
+The earlier eruptions seem to have been chiefly granitic, though this
+must not be understood in too wide a sense, since there are granite
+formations even as late as the Tertiary period; those of the middle
+periods were mostly porphyries and basalts; while in the more recent
+ones, lavas predominate. We have as yet no clew to the laws by which
+this distribution of volcanic elements in the formation of the earth
+is regulated; but there is found to be a difference in the crystals of
+the Plutonic rocks belonging to different ages, which, when fully
+understood may enable us to determine the age of any Plutonic rock by
+its mode of crystallization; so that the mineralogist will as readily
+tell you by its crystals whether a bit of stone of igneous origin
+belongs to this or that period of the world's history, as the
+palæontologist will tell you by its fossils whether a piece of rock
+of aqueous origin belongs to the Silurian or Devonian or Carboniferous
+deposits.
+
+Although subsequent investigations have multiplied so extensively not
+only the number of geological periods, but also the successive
+creations that have characterized them, yet the first general division
+into three great eras was nevertheless founded upon a broad and true
+generalization. In the first stratified rocks in which any organic
+remains are found, the highest animals are fishes, and the highest
+plants are cryptogams; in the middle periods reptiles come in,
+accompanied by fern and moss forests; in later times quadrupeds are
+introduced, with a dicotyledonous vegetation. So closely does the
+march of animal and vegetable life keep pace with the material
+progress of the world, that we may well consider these three
+divisions, included under the first general classification of its
+physical history, as the three Ages of Nature; the more important
+epochs which subdivide them may be compared to so many great
+dynasties, while the lesser periods are the separate reigns contained
+therein. Of such epochs there are ten, well known to geologists; of
+the lesser periods about sixty are already distinguished, while many
+more loom up from the dim regions of the past, just discerned by the
+eye of science, though their history is not yet unravelled.
+
+Before proceeding further, I will enumerate the geological epochs in
+their succession, confining myself, however, to such as are perfectly
+well established, without alluding to those of which the limits are
+less definitely determined, and which are still subject to doubts and
+discussions among geologists. As I do not propose to make here any
+treatise of Geology, but simply to place before my readers some
+pictures of the old world, with the animals and plants that have
+inhabited it at various times, I shall avoid, as far as possible, all
+debatable ground, and confine myself to those parts of my subject
+which are best known, and can therefore be more clearly presented.
+
+[Illustration: FOSSIL SCORPION.--SILURIAN PERIOD.]
+
+First, we have the Azoic period, _devoid of life_, as its name
+signifies,--namely, the earliest stratified deposits upon the heated
+film forming the first solid surface of the earth, in which no trace
+of living thing has ever been found. Next comes the Silurian period,
+when the crust of the earth had thickened and cooled sufficiently to
+render the existence of animals and plants upon it possible, and when
+the atmospheric conditions necessary to their maintenance were already
+established. Many of the names given to these periods are by no means
+significant of their character, but are merely the result of accident:
+as, for instance, that of Silurian, given by Sir Roderick Murchison to
+this set of beds, because he first studied them in that part of Wales
+occupied by the ancient tribe of the Silures. The next period, the
+Devonian, was for a similar reason named after the country of
+Devonshire in England, where it was first investigated. Upon this
+follows the Carboniferous period, with the immense deposits of coal
+from which it derives its name. Then comes the Permian period, named,
+again, from local circumstances, the first investigation of its
+deposits having taken place in the province of Permia in Russia. Next
+in succession we have the Triassic period, so called from the trio of
+rocks, the red sandstone, Muschel Kalk (shell-limestone), and Keuper
+(clay), most frequently combined in its formations; the Jurassic, so
+amply illustrated in the chain of the Jura, where geologists first
+found the clew to its history; and the Cretaceous period, to which the
+chalk cliffs of England and all the extensive chalk deposits belong.
+Upon these follow the so-called Tertiary formations, divided into
+three periods, all of which have received most characteristic names in
+this epoch of the world's history we see the first approach to a
+condition of things resembling that now prevailing, and Sir Charles
+Lyell has most fitly named its three divisions, the Eocene, Miocene,
+and Pliocene. The termination of the three words is made from the
+Greek word _Kainos_, recent; while _Eos_ signifies dawn, _Meion_ less,
+and _Pleion_ more. Thus Eocene indicates the dawn of recent species,
+Pliocene their increase, while Miocene, the intermediate term, means
+less recent. Above these deposits comes what has been called in
+science the present period,--_the modern times_ of the geologist,--that
+period to which man himself belongs, and since the beginning of which,
+though its duration be counted by hundreds of thousands of years,
+there has been no alteration in the general configuration of the
+earth, consequently no important modification of its climatic
+conditions, and no change in the animals and plants inhabiting it.
+
+[Illustration: CRUSTACEA.--DEVONIAN PERIOD.]
+
+[Illustration: FISH OF THE DEVONIAN PERIOD.]
+
+[Illustration: FISH OF THE CARBONIFEROUS PERIOD.]
+
+[Illustration: FOSSIL VEGETATION OF CARBONIFEROUS PERIOD.]
+
+[Illustration: FISH OF THE PERMIAN PERIOD.]
+
+I have spoken of the first of these periods, the Azoic, as having
+been absolutely devoid of life, and I believe this statement to be
+strictly true; but I ought to add that there is a difference of
+opinion among geologists upon this point, many believing that the
+first surface of our globe may have been inhabited by living beings,
+but that all traces of their existence have been obliterated by the
+eruptions of melted materials, which not only altered the character of
+those earliest stratified rocks, but destroyed all the organic remains
+contained in them. It will be my object to show, not only that the
+absence of the climatic and atmospheric conditions essential to
+organic life, as we understand it, must have rendered the previous
+existence of any living beings impossible, but also that the
+completeness of the Animal Kingdom in those deposits where we first
+find organic remains, its intelligible and coherent connections with
+the successive creations of all geological times and with the animals
+now living, afford the strongest internal evidence that we have indeed
+found in the lower Silurian formations, immediately following the
+Azoic, the beginning of life upon earth. When a story seems to us
+complete and consistent from the beginning to the end, we shall not
+seek for a first chapter, even though the copy in which we have read
+it be so torn and defaced as to suggest the idea that some portion of
+it may have been lost. The unity of the work, as a whole, is an
+incontestable proof that we possess it in its original integrity. The
+validity of this argument will be recognized, perhaps, only by those
+naturalists to whom the Animal Kingdom has begun to appear as a
+connected whole. For those who do not see order in Nature it can have
+no value.
+
+[Illustration: FOSSILS OF TRIASSIC VEGETATION.]
+
+[Illustration: BIRD OF THE JURASSIC PERIOD.(The Oldest Bird.)]
+
+[Illustration: SKELETON OF BIRD OF THE CRETACEOUS PERIOD.]
+
+[Illustration: SKELETON OF ANIMAL OF THE EOCENE PERIOD.]
+
+For a table containing the geological periods in their succession, I
+would refer to any modern text-book of Geology, or to an article in
+the _Atlantic Monthly_ for March, 1862, upon "Methods of Study in
+Natural History," where they are given in connection with the order of
+introduction of animals upon earth.
+
+Were these sets of rocks found always in the regular sequence in which
+I have enumerated them, their relative age would be easily
+determined, for their superposition would tell the whole story: the
+lowest would, of course, be the oldest, and we might follow without
+difficulty the ascending series, till we reached the youngest and
+uppermost deposits. But their succession has been broken up by
+frequent and violent alterations in the configuration of the globe.
+Land and water have changed their level,--islands have been
+transformed to continents,--sea-bottoms have become dry land, and dry
+land has sunk to form sea-bottoms,--Alps and Himalayas, Pyrenees and
+Apennines, Alleghanies and Rocky Mountains, have had their stormy
+birthdays since many of these beds have been piled one above another,
+and there are but few spots on the earth's surface where any number of
+them may be found in their original order and natural position. When
+we remember that Europe, which lies before us on the map as a
+continent, was once an archipelago of islands,--that, where the
+Pyrenees raise their rocky barrier between France and Spain, the
+waters of the Mediterranean and Atlantic met,--that, where the British
+Channel flows, dry land united England and France, and Nature in those
+days made one country of the lands parted since by enmities deeper
+than the waters that run between,--when we remember, in short, all the
+fearful convulsions that have torn asunder the surface of the earth,
+as if her rocky record had indeed been written on paper, we shall find
+a new evidence of the intellectual unity which holds together the
+whole physical history of the globe in the fact that through all the
+storms of time the investigator is able to trace one unbroken thread
+of thought from the beginning to the present hour.
+
+[Illustration: SKELETON OF ANIMAL OF THE MIOCENE PERIOD.]
+
+[Illustration: SKELETON OF ANIMAL OF THE PLIOCENE PERIOD.]
+
+The tree is known by its fruits,--and the fruits of chance are
+incoherence, incompleteness, unsteadiness, the stammering utterance of
+blind, unreasoning force. A coherence that binds all the geological
+ages in one chain, a stability of purpose that completes in the beings
+born to-day an intention expressed in the first creatures that swam in
+the Silurian ocean or crept upon its shores, a steadfastness of
+thought, practically recognized by man, if not acknowledged by him,
+whenever he traces the intelligent connection between the facts of
+Nature and combines them into what he is pleased to call his system of
+Geology, or Zoölogy, or Botany,--these things are not the fruits of
+chance or of an unreasoning force, but the legitimate results of
+intellectual power. There is a singular lack of logic, as it seems to
+me, in the views of the materialistic naturalists. While they consider
+classification, or, in other words, their expression of the relations
+between animals or between physical facts of any kind, as the work of
+their intelligence, they believe the relations themselves to be the
+work of physical causes. The more direct inference surely is, that, if
+it requires an intelligent mind to recognize them, it must have
+required an intelligent mind to establish them. These relations
+existed before man was created; they have existed ever since the
+beginning of time; hence, what we call the classification of facts is
+not the work of his mind in any direct original sense, but the
+recognition of an intelligent action prior to his own existence.
+
+There is, perhaps, no part of the world, certainly none familiar to
+science, where the early geological periods can be studied with so
+much ease and precision as in the United States. Along their northern
+borders, between Canada and the United States, there runs the low line
+of hills known as the Laurentian Hills. Insignificant in height,
+nowhere rising more than fifteen hundred or two thousand feet above
+the level of the sea, these are nevertheless the first mountains that
+broke the uniform level of the earth's surface and lifted themselves
+above the waters. Their low stature, as compared with that of other
+more lofty mountain-ranges, is in accordance with an invariable rule,
+by which the relative age of mountains may be estimated. The oldest
+mountains are the lowest, while the younger and more recent ones tower
+above their elders, and are usually more torn and dislocated also.
+This is easily understood, when we remember that all mountains and
+mountain-chains are the result of upheavals, and that the violence of
+the outbreak must have been in proportion to the strength of the
+resistance. When the crust of the earth was so thin that the heated
+masses within easily broke through it, they were not thrown to so
+great a height, and formed comparatively low elevations, such as the
+Canadian hills or the mountains of Bretagne and Wales. But in later
+times, when young, vigorous giants, such as the Alps, the Himalayas,
+or, later still, the Rocky Mountains, forced their way out from their
+fiery prison-house, the crust of the earth was much thicker, and
+fearful indeed must have been the convulsions which attended their
+exit.
+
+[Illustration: A PHYSICAL MAP OF THE UNITED STATES.]
+
+The Laurentian Hills form, then, a granite range, stretching from
+Eastern Canada to the Upper Mississippi, and immediately along its
+base are gathered the Azoic deposits, the first stratified beds, in
+which the absence of life need not surprise us, since they were
+formed beneath a heated ocean. As well might we expect to find the
+remains of fish or shells or crabs at the bottom of geysers or of
+boiling springs, as on those early shores bathed by an ocean of which
+the heat must have been so intense. Although, from the condition in
+which we find it, this first granite range has evidently never been
+disturbed by any violent convulsion since its first upheaval, yet
+there has been a gradual rising of that part of the continent; for the
+Azoic beds do not lie horizontally along the base of the Laurentian
+Hills in the position in which they must originally have been
+deposited, but are lifted and rest against their slopes. They have
+been more or less dislocated in this process, and are greatly
+metamorphized by the intense heat to which they must have been
+exposed. Indeed, all the oldest stratified rocks have been baked by
+the prolonged action of heat.
+
+It may be asked how the materials for those first stratified deposits
+were provided. In later times, when an abundant and various soil
+covered the earth, when every river brought down to the ocean, not
+only its yearly tribute of mud or clay or lime, but the débris of
+animals and plants that lived and died in its waters or along its
+banks, when every lake and pond deposited at its bottom in successive
+layers the lighter or heavier materials floating in its waters and
+settling gradually beneath them, the process by which stratified
+materials are collected and gradually harden into rock is more easily
+understood. But when the solid surface of the earth was only just
+beginning to form, it would seem that the floating matter in the sea
+can hardly have been in sufficient quantity to form any extensive
+deposits. No doubt there was some abrasion even of that first crust;
+but the more abundant source of the earliest stratification is to be
+found in the submarine volcanoes that poured their liquid streams into
+the first ocean. At what rate these materials would be distributed and
+precipitated in regular strata it is impossible to determine; but that
+volcanic materials were so deposited in layers is evident from the
+relative position of the earliest rocks. I have already spoken of the
+innumerable chimneys perforating the Azoic beds, narrow outlets of
+Plutonic rock, protruding through the earliest strata. Not only are
+such funnels filled with the crystalline mass of granite that flowed
+through them in a liquid state, but it has often poured over their
+sides, mingling with the stratified beds around. In the present state
+of our knowledge, we can explain such appearances only by supposing
+that the heated materials within the earth's crust poured out
+frequently, meeting little resistance,--that they then scattered and
+were precipitated in the ocean around, settling in successive strata
+at its bottom,--that through such strata the heated masses within
+continued to pour again and again, forming for themselves the
+chimney-like outlets above mentioned.
+
+Such, then, was the earliest American land,--a long, narrow island,
+almost continental in its proportions, since it stretched from the
+eastern borders of Canada nearly to the point where now the base of
+the Rocky Mountains meets the plain of the Mississippi Valley. We may
+still walk along its ridge and know that we tread upon the ancient
+granite that first divided the waters into a northern and southern
+ocean; and if our imaginations will carry us so far, we may look down
+toward its base and fancy how the sea washed against this earliest
+shore of a lifeless world. This is no romance, but the bald, simple
+truth; for the fact that this granite band was lifted out of the
+waters so early in the history of the world, and has not since been
+submerged, has, of course, prevented any subsequent deposits from
+forming above it. And this is true of all the northern part of the
+United States. It has been lifted gradually, the beds deposited in one
+period being subsequently raised, and forming a shore along which
+those of the succeeding one collected, so that we have their whole
+sequence before us. In regions where all the geological deposits
+(Silurian, Devonian, carboniferous, permian, triassic, etc.) are piled
+one upon another, and we can get a glimpse of their internal relations
+only where some rent has laid them open, or where their ragged edges,
+worn away by the abrading action of external influences, expose to
+view their successive layers, it must, of course, be more difficult to
+follow their connection. For this reason the American continent offers
+facilities to the geologist denied to him in the so-called Old World,
+where the earlier deposits are comparatively hidden, and the broken
+character of the land, intersected by mountains in every direction,
+renders his investigation still more difficult. Of course, when I
+speak of the geological deposits as so completely unveiled to us here,
+I do not forget the sheet of drift which covers the continent from
+north to south, and which we shall discuss hereafter, when I reach
+that part of my subject. But the drift is only a superficial and
+recent addition to the soil, resting loosely above the other
+geological deposits, and arising, as we shall see, from very different
+causes.
+
+In this article I have intended to limit myself to a general sketch of
+the formation of the Laurentian Hills with the Azoic stratified beds
+resting against them. In the Silurian epoch following the Azoic we
+have the first beach on which any life stirred; it extended along the
+base of the Azoic beds, widening by its extensive deposits the narrow
+strip of land already upheaved. I propose ... to invite my readers to
+a stroll with me along that beach.
+
+With what interest do we look upon any relic of early human history!
+The monument that tells of a civilization whose hieroglyphic records
+we cannot even decipher, the slightest trace of a nation that vanished
+and left no sign of its life except the rough tools and utensils
+buried in the old site of its towns or villages, arouses our
+imagination and excites our curiosity. Men gaze with awe at the
+inscription on an ancient Egyptian or Assyrian stone; they hold with
+reverential touch the yellow parchment-roll whose dim, defaced
+characters record the meagre learning of a buried nationality; and the
+announcement, that for centuries the tropical forests of Central
+America have hidden within their tangled growth the ruined homes and
+temples of a past race, stirs the civilized world with a strange, deep
+wonder.
+
+To me it seems, that to look on the first land that was ever lifted
+above the waste of waters, to follow the shore where the earliest
+animals and plants were created when the thought of God first
+expressed itself in organic forms, to hold in one's hand a bit of
+stone from an old sea-beach, hardened into rock thousands of
+centuries ago, and studded with the beings that once crept upon its
+surface or were stranded there by some retreating wave, is even of
+deeper interest to men than the relies of their own race, for these
+things tell more directly of the thoughts and creative acts of God.
+
+Standing in the neighborhood of Whitehall, near Lake George, one may
+look along such a seashore, and see it stretching westward and sloping
+gently southward as far as the eye can reach. It must have had a very
+gradual slope, and the waters must have been very shallow; for at that
+time no great mountains had been uplifted, and deep oceans are always
+the concomitants of lofty heights. We do not, however, judge of this
+by inference merely; we have an evidence of the shallowness of the sea
+in those days in the character of the shells found in the Silurian
+deposits, which shows that they belonged in shoal waters.
+
+Indeed, the fossil remains of all times tell us almost as much of the
+physical condition of the world at different epochs as they do of its
+animal and vegetable population. When Robinson Crusoe first caught
+sight of the footprint on the sand, he saw in it more than the mere
+footprint, for it spoke to him of the presence of men on his desert
+island. We walk on the old geological shores, like Crusoe along his
+beach, and the footprints we find there tell us, too, more than we
+actually see in them. The crust of our earth is a great cemetery,
+where the rocks are tombstones on which the buried dead have written
+their own epitaphs. They tell us not only who they were and when and
+where they lived, but much also of the circumstances under which they
+lived. We ascertain the prevalence of certain physical conditions at
+special epochs by the presence of animals and plants whose existence
+and maintenance required such a state of things, more than by any
+positive knowledge respecting it. Where we find the remains of
+quadrupeds corresponding to our ruminating animals, we infer not only
+land, but grassy meadows also, and an extensive vegetation; where we
+find none but marine animals, we know the ocean must have covered the
+earth; the remains of large reptiles, representing, though in gigantic
+size, the half aquatic, half terrestrial reptiles of our own period,
+indicate to us the existence of spreading marshes still soaked by the
+retreating waters; while the traces of such animals as live now in
+sand and shoal waters, or in mud, speak to us of shelving sandy
+beaches and of mud-flats. The eye of the Trilobite tells us that the
+sun shone on the old beach where he lived; for there is nothing in
+nature without a purpose, and when so complicated an organ was made to
+receive the light, there must have been light to enter it. The immense
+vegetable deposits in the Carboniferous period announce the
+introduction of an extensive terrestrial vegetation; and the
+impressions left by the wood and leaves of the trees show that these
+first forests must have grown in a damp soil and a moist atmosphere.
+In short, all the remains of animals and plants hidden in the rocks
+have something to tell of the climatic conditions and the general
+circumstances under which they lived, and the study of fossils is to
+the naturalist a thermometer by which he reads the variations of
+temperature in past times, a plummet by which he sounds the depths of
+the ancient oceans,--a register, in fact, of all the important
+physical changes the earth has undergone.
+
+But although the animals of the early geological deposits indicate
+shallow seas by their similarity to our shoal-water animals, it must
+not be supposed that they are by any means the same. On the contrary,
+the old shells, crustacea, corals, etc., represent types which have
+existed in all times with the same essential structural elements, but
+under different specific forms in the several geological periods. And
+here it may not be amiss to say something of what are called by
+naturalists _representative types_.
+
+The statement that different sets of animals and plants have
+characterized the successive epochs is often understood as indicating
+a difference of another kind than that which distinguishes animals now
+living in different parts of the world. This is a mistake. There are
+so-called representative types all over the globe, united to each
+other by structural relations and separated by specific differences of
+the same kind as those that unite and separate animals of different
+geological periods. Take, for instance, mud-flats or sandy shores in
+the same latitudes of Europe and America; we find living on each,
+animals of the same structural character and of the same general
+appearance, but with certain specific differences, as of color, size,
+external appendages, etc. They represent each other on the two
+continents. The American wolves, foxes, bears, rabbits, are not the
+same as the European, but those of one continent are as true to their
+respective types as those of the other; under a somewhat different
+aspect they represent the same groups of animals. In certain
+latitudes, or under conditions of nearer proximity, these differences
+may be less marked. It is well known that there is a great monotony
+of type, not only among animals and plants, but in the human races
+also, throughout the Arctic regions; and some animals characteristic
+of the high North reappear under such identical forms in the
+neighborhood of the snow-fields in lofty mountains, that to trace the
+difference between the ptarmigans, rabbits, and other gnawing animals
+of the Alps, for instance, and those of the Arctics, is among the most
+difficult problems of modern science.
+
+And so it is also with the animated world of past ages; in similar
+deposits of sand, mud, or lime, in adjoining regions of the same
+geological age, identical remains of animals and plants may be found;
+while at greater distances, but under similar circumstances,
+representative species may occur. In very remote regions, however,
+whether the circumstances be similar or dissimilar, the general aspect
+of the organic world differs greatly, remoteness in space being thus
+in some measure an indication of the degree of affinity between
+different faunæ. In deposits of different geological periods
+immediately following each other, we sometimes find remains of animals
+and plants so closely allied to those of earlier or later periods that
+at first sight the specific differences are hardly discernible. The
+difficulty of solving these questions, and of appreciating correctly
+the differences and similarities between such closely allied
+organisms, explains the antagonistic views of many naturalists
+respecting the range of existence of animals, during longer or shorter
+geological periods; and the superficial way in which discussions
+concerning the transition of species are carried on, is mainly owing
+to an ignorance of the conditions above alluded to. My own personal
+observation and experience in these matters have led me to the
+conviction that every geological period has had its own
+representatives, and that no single species has been repeated in
+successive ages.
+
+The laws regulating the geographical distribution of animals, and
+their combination into distinct zoölogical provinces called faunæ,
+with definite limits, are very imperfectly understood as yet; but so
+closely are all things linked together from the beginning that I am
+convinced we shall never find the clew to their meaning till we carry
+on our investigations in the past and the present simultaneously. The
+same principle according to which animal and vegetable life is
+distributed over the surface of the earth now, prevailed in the
+earliest geological periods. The geological deposits of all times have
+had their characteristic faunæ under various zones, their zoölogical
+provinces presenting special combinations of animal and vegetable life
+over certain regions, and their representative types reproducing in
+different countries, but under similar latitudes, the same groups with
+specific differences.
+
+Of course, the nearer we approach the beginning of organic life, the
+less marked do we find the differences to be, and for a very obvious
+reason. The inequalities of the earth's surface, her mountain-barriers
+protecting whole continents from the Arctic winds, her open plains
+exposing others to the full force of the polar blasts, her snug
+valleys and her lofty heights, her tablelands and rolling prairies,
+her river-systems and her dry deserts, her cold ocean-currents pouring
+down from the high North on some of her shores, while warm ones from
+tropical seas carry their softer influence to others,--in short, all
+the contrasts in the external configuration of the globe, with the
+physical conditions attendant upon them, are naturally accompanied by
+a corresponding variety in animal and vegetable life.
+
+But in the Silurian age, when there were no elevations higher than the
+Canadian hills, when water covered the face of the earth, with the
+exception of a few isolated portions lifted above the almost universal
+ocean, how monotonous must have been the conditions of life! And what
+should we expect to find on those first shores? If we are walking on a
+sea-beach to-day, we do not look for animals that haunt the forests or
+roam over the open plains, or for those that live in sheltered valleys
+or in inland regions or on mountain-heights. We look for Shells, for
+Mussels and Barnacles, for Crabs, for Shrimps, for Marine Worms, for
+Star-Fishes and Sea-Urchins, and we may find here and there a fish
+stranded on the sand or tangled in the seaweed.
+
+[Illustration]
+
+
+
+
+SOME RECORDS OF THE ROCKS
+
+(FROM A FIRST BOOK IN GEOLOGY.)
+
+BY N.S. SHALER, S.D.[1]
+
+[Footnote 1: Copyright, 1884, by N.S. Shaler.]
+
+[Illustration]
+
+The geologist cannot find his way back in the record of the great
+stone book, to the far-off day when life began. The various changes
+that come over rocks from the action of heat, of water, and of
+pressure, have slowly modified these ancient beds, so that they no
+longer preserve the frames of the animals that were buried in them.
+
+These old rocks, which are so changed that we cannot any longer make
+sure that any animals lived in them, are called the "archæan," which
+is Greek for ancient. They were probably mud and sand and limestone
+when first made, but they have been changed to mica schists, gneiss,
+granite, marble, and other crystalline rocks. When any rock becomes
+crystalline, the fossils dissolve and disappear, as coins lose their
+stamp and form when they are melted in the jeweller's gold-pot.
+
+These ancient rocks that lie deepest in the earth are very thick, and
+must have taken a great time in building; great continents must have
+been worn down by rain and waves in order to supply the waste out of
+which they were made. It is tolerably certain that they took as much
+time during their making as has been required for all the other times
+since they were formed. During the vast ages of this archæan the life
+of our earth began to be. We first find many certain evidences of life
+in the rocks which lie on top of the archæan rock, and are known as
+the Cambriani and Silurian periods. There we have creatures akin to
+our corals and crabs and worms, and others that are the distant
+kindred of the cuttle-fishes and of our lamp-shells. There were no
+backboned animals, that is to say, no land mammals, reptiles, or
+fishes at this stage of the earth's history. It is not likely that
+there was any land life except of plants and those forms like the
+lowest ferns, and probably mosses. Nor is it likely that there were
+any large continents as at the present time, but rather a host of
+islands lying where the great lands now are, the budding tops of the
+continents just appearing above the sea.
+
+Although the life of this time was far simpler than at the present
+day, it had about as great variety as we would find on our present
+sea-floors. There were as many different species living at the same
+time on a given surface.
+
+The Cambrian and Silurian time--the time before the coming of the
+fishes--must have endured for many million years without any great
+change in the world. Hosts of species lived and died; half a dozen
+times or more the life of the earth was greatly changed. New species
+came much like those that had gone before, and only a little gain here
+and there was perceptible at any time. Still, at the end of the
+Silurian, the life of the world had climbed some steps higher in
+structure and in intelligence.
+
+[Illustration: FIG. 1. NORTH AMERICA IN CAMBRIAN TIME.]
+
+The next set of periods is known as the Devonian. It is marked by the
+rapid extension of the fishes; for, although the fishes began in the
+uppermost Silurian, they first became abundant in this time. These,
+the first strong-jawed tyrants of the sea, came all at once, like a
+rush of the old Norman pirates into the peaceful seas of Great
+Britain. They made a lively time among the sluggish beings of that
+olden sea. Creatures that were able to meet feebler enemies were swept
+away or compelled to undergo great changes, and all the life of the
+oceans seems to have a spur given to it by these quicker-formed and
+quicker-willed animals. In this Devonian section of our rocks we have
+proofs that the lands were extensively covered with forests of low
+fern trees, and we find the first trace of air-breathing animals in
+certain insects akin to our dragon-flies. In this stage of the earth's
+history the fishes grew constantly more plentiful, and the seas had a
+great abundance of corals and crinoids. Except for the fishes, there
+were no very great changes in the character of the life from that
+which existed in the earlier time of the Cambrian and Silurian. The
+animals are constantly changing, but the general nature of the life
+remains the same as in the earlier time.
+
+[Illustration: FIG. 2. RANICEPS LYELLI--COAL TIME SALAMANDER.]
+
+In the Carboniferous or coal-bearing age, we have the second great
+change in the character of the life on the earth. Of the earlier
+times, we have preserved only the rocks formed in the seas. But rarely
+do we find any trace of the land life or even of the life that lived
+along the shores. In this Carboniferous time, however, we have very
+extensive sheets of rocks which were formed in swamps in the way shown
+in the earlier part of this book. They constitute our coal-beds,
+which, though much worn away by rain and sea, still cover a large part
+of the land surface. These beds of coal grew in the air, and, although
+the swamps where they were formed had very little animal life in them,
+we find some fossils which tell us that the life of the land was
+making great progress; there are new insects, including beetles,
+cockroaches, spiders, and scorpions, and, what is far more important,
+there are some air-breathing, back-boned animals, akin to the
+salamanders and water-dogs of the present day. These were nearly as
+large as alligators, and of much the same shape, but they were
+probably born from the egg in the shape of tadpoles and lived for a
+time in the water as our young frogs, toads, and salamanders do. This
+is the first step upwards from the fishes to land vertebrates; and we
+may well be interested in it, for it makes one most important advance
+in creatures through whose lives our own existence became possible.
+Still, these ancient woods of the coal period must have had little of
+the life we now associate with the forests; there were still no birds,
+no serpents, no true lizards, no suck-giving animals, no flowers, and
+no fruits. These coal-period forests were sombre wastes of shade, with
+no sound save those of the wind, the thunder, and the volcano, or of
+the running streams and the waves on the shores.
+
+In the seas of the Carboniferous time, we notice that the ancient life
+of the earth is passing away. Many creatures, such as the trilobites,
+die out, and many other forms such as the crinoids or sea lilies
+become fewer in kind and of less importance. These marks of decay in
+the marine life continue into the beds just after the Carboniferous,
+known as the Permian, which are really the last stages of the
+coal-bearing period.
+
+When with the changing time we pass to the beds known as the Triassic,
+which were made just after the close of the Carboniferous time, we
+find the earth undergoing swift changes in its life. The moist climate
+and low lands that caused the swamps to grow so rapidly have ceased to
+be, and in their place we appear to have warm, dry air, and higher
+lands.
+
+On these lands of the Triassic time the air-breathing life made very
+rapid advances. The plants are seen to undergo considerable changes.
+The ferns no longer make up all the forests, but trees more like the
+pines began to abound, and insects became more plentiful and more
+varied.
+
+[Illustration: FIG. 3. CYCAS CIRCINALIS, AKIN TO HIGHEST PLANTS OF
+COAL TIME.]
+
+Hitherto the only land back-boned animal was akin to our salamanders.
+Now we have true lizards in abundance, many of them of large size.
+Some of them were probably plant-eaters, but most were flesh-eaters;
+some seem to have been tenants of the early swamps, and some dwelt in
+the forests.
+
+The creatures related to the salamanders have increased in the variety
+of their forms to a wonderful extent. We know them best by the tracks
+which they have left on the mud stones formed on the borders of lakes
+or the edge of the sea. In some places these footprints are found in
+amazing numbers and perfection. The best place for them is in the
+Connecticut Valley, near Turner's Falls, Mass. At this point the red
+sandstone and shale beds, which are composed of thin layers having a
+total thickness of several hundred feet, are often stamped over by
+these footprints like the mud of a barnyard. From the little we can
+determine from these footprints, the creatures seem to have been
+somewhat related to our frogs, but they generally had tails, and,
+though provided with four legs, were in the habit of walking on the
+hind ones alone like the kangaroo. A few of these tracks are shown in
+the figure on this page.
+
+[Illustration: FIG. 4. FOOT-PRINTS, CONNECTICUT SANDSTONES.]
+
+These strange creatures were of many different species. Some of them
+must have been six or seven feet high, for their steps are as much as
+three feet apart, and seem to imply a creature weighing several
+hundred pounds. Others were not bigger than robins. Strangely enough,
+we have never found their bones nor the creatures on which they fed,
+and but for the formation of a little patch of rocks here and there we
+should not have had even these footprints to prove to us that such
+creatures had lived in the Connecticut Valley in this far-off time.
+
+[Illustration: FIG. 5. FOOT-PRINT, TURNER'S FALLS.]
+
+But these wonderful forms are less interesting than two or three
+little fossil jaw-bones that prove to us that in this Triassic time
+the earth now bore another animal more akin to ourselves, in the shape
+of a little creature that gave suck to its young. Once more life takes
+a long upward step in this little opossum-like animal, perhaps the
+first creature whose young was born alive. These little creatures
+called Microlestes or Dromatherium, of which only one or two different
+but related species have been found in England and in North Carolina,
+appear to have been insect-eaters of about the size and shape of the
+Australian creature shown in Fig. 7. So far we know it in but few
+specimens,--altogether only an ounce or two of bones,--but they are
+very precious monuments of the past.
+
+[Illustration: FIG. 6. DROMATHERIUM SYLVESTRE AND TEETH OF MICROLESTES
+ANTIQUUS.]
+
+In this Triassic time the climate appears to have been rather dry, for
+in it we have many extensive deposits of salt formed by the
+evaporation of closed lakes, of seas, such as are now forming on the
+bottom of the Dead Sea, and the Great Salt Lake of Utah, and a hundred
+or more other similar basins of the present day.
+
+[Illustration: FIG. 7. MYRMECOBIUS.]
+
+In the sea animals of this time we find many changes. Already some of
+the giant lizard-like animals, which first took shape on the land, are
+becoming swimming-animals. They changed their feet to paddles, which,
+with the help of a flattened tail, force them through the water.
+
+The fishes on which these great swimming lizards preyed are more like
+the fishes of our present day than they were before. The trilobites
+are gone, and of the crinoids only a remnant is left. Most of the
+corals of the earlier days have disappeared, but the mollusks have not
+changed more than they did at several different times in the earliest
+stages of the earth's history.
+
+[Illustration: FIG. 8. ICHTHYOSAURUS AND PLESIOSAURUS.]
+
+After the Trias comes a long succession of ages in which the life of
+the world is steadily advancing to higher and higher planes; but for a
+long time there is no such startling change as that which came in the
+passage from the coal series of rocks to the Trias. This long set of
+periods is known to geologists as the age of reptiles. It is well
+named, for the kindred of the lizards then had the control of the
+land. There were then none of our large fish to dispute their control,
+so they shaped themselves to suit all the occupations that could give
+them a chance for a living. Some remained beasts of prey like our
+alligators, but grew to larger size; some took to eating the plants,
+and came to walk on their four legs as our ordinary beasts do, no
+longer dragging themselves on their bellies as do the lizard and
+alligator, their lower kindred. Others became flying creatures like
+our bats, only vastly larger, often with a spread of wing of fifteen
+or twenty feet. Yet others, even as strangely shaped, dwelt with the
+sharks in the sea.
+
+[Illustration: FIG. 9. REPTILES OF JURASSIC PERIOD.]
+
+In this time of the earth's history we have the first bird-like forms.
+They were feathered creatures, with bills carrying true teeth, and
+with strong wings; but they were reptiles in many features, having
+long, pointed tails such as none of our existing birds have. They show
+us that the birds are the descendants of reptiles, coming off from
+them as a branch does from the parent tree. The tortoises began in
+this series of rocks. At first they are marine or swimming forms, the
+box-turtles coming later. Here too begin many of the higher insects.
+Creatures like moths and bees appear, and the forests are enlivened
+with all the important kinds of insects, though the species were very
+different from those now living.
+
+In the age of reptiles the plants have made a considerable advance.
+Palms are plenty; forms akin to our pines and firs abound, and the old
+flowerless group of ferns begins to shrink in size, and no longer
+spreads its feathery foliage over all the land as before. Still there
+were none of our common broad-leaved trees; the world had not yet
+known the oaks, birches, maples, or any of our hard-wood trees that
+lose their leaves in autumn; nor were the flowering plants, those with
+gay blossoms, yet on the earth. The woods and fields were doubtless
+fresh and green, but they wanted the grace of blossoms, plants, and
+singing-birds. None of the animals could have had the social qualities
+or the finer instincts that are so common among animals of the present
+day. There were probably no social animals like our ants and bees, no
+merry singing creatures; probably no forms that went in herds. Life
+was a dull round of uncared-for birth, cruel self-seeking, and of
+death. The animals at best were clumsy, poorly-endowed creatures, with
+hardly more intelligence than our alligators.
+
+The little thread of higher life begun in the Microlestes and
+Dromatherium, the little insect-eating mammals of the forest, is
+visible all through this time. It held in its warm blood the powers of
+the time to come, but it was an insignificant thing among the mighty
+cold-blooded reptiles of these ancient lands. There are several
+species of them, but they are all small, and have no chance to make
+headway against the older masters of the earth.
+
+The Jurassic or first part of the reptilian time shades insensibly
+into the second part, called the Cretaceous, which immediately follows
+it. During this period the lands were undergoing perpetual changes;
+rather deep seas came to cover much of the land surfaces, and there is
+some reason to believe that the climate of the earth became much
+colder than it had been, at least in those regions where the great
+reptiles had flourished. It may be that it is due to a colder climate
+that we owe the rapid passing away of this gigantic reptilian life of
+the previous age. The reptiles, being cold-blooded, cannot stand even
+a moderate winter cold, save when they are so small that they can
+crawl deep into crevices in the rocks to sleep the winter away,
+guarded from the cold by the warmth of the earth. At any rate these
+gigantic animals rapidly ceased to be, so that by the middle of the
+Cretaceous period they were almost all gone, except those that
+inhabited the sea; and at the end of this time they had shrunk to
+lizards in size. The birds continue to increase and to become more
+like those of our day; their tails shrink away, their long bills lose
+their teeth; they are mostly water-birds of large size, and there are
+none of our songsters yet; still they are for the first time perfect
+birds, and no longer half-lizard in their nature.
+
+The greatest change in the plants is found in the coming of the
+broad-leaved trees belonging to the families of our oaks, maples, etc.
+Now for the first time our woods take on their aspect of to-day; pines
+and other cone-bearers mingle with the more varied foliage of
+nut-bearing or large-seeded trees. Curiously enough, we lose sight of
+the little mammals of the earlier time. This is probably because there
+is very little in the way of land animals of this period preserved to
+us. There are hardly any mines or quarries in the beds of this age to
+bring these fossils to light. In the most of the other rocks there is
+more to tempt man to explore them for coal ores or building stones.
+
+In passing from the Cretaceous to the Tertiary, we enter upon the
+threshold of our modern world. We leave behind all the great wonders
+of the old world, the gigantic reptiles, the forests of tree ferns,
+the seas full of ammonites and belemnites, and come among the no less
+wonderful but more familiar modern forms. We come at once into lands
+and seas where the back-boned animals are the ruling beings. The
+reptiles have shrunk to a few low forms,--the small lizards, the
+crocodiles and alligators, the tortoises and turtles, and, as if to
+mark more clearly the banishment of this group from their old empire,
+the serpents, which are peculiarly degraded forms of reptiles which
+have lost the legs they once had, came to be the commonest reptiles of
+the earth.
+
+The first mammals that have no pouches now appear. In earlier times,
+the suck-giving animals all belonged to the group that contains our
+opossums, kangaroos, etc. These creatures are much lower and feebler
+than the mammals that have no pouches. Although they have probably
+been on the earth two or three times as long as the higher mammals,
+they have never attained any eminent success whatever; they cannot
+endure cold climates; none of them are fitted for swimming as are the
+seals and whales, or for flying as the bats, or for burrowing as the
+moles; they are dull, weak things, which are not able to contend with
+their stronger, better-organized, higher kindred. They seem not only
+weak, but unable to fit themselves to many different kinds of
+existence.
+
+In the lower part of the Tertiary rocks, we find at once a great
+variety of large beasts that gave suck to their young. It is likely
+that these creatures had come into existence in a somewhat earlier
+time in other lands, where we have not been able to study the fossils;
+for to make their wonderful forms slowly, as we believe them to have
+been made, would require a very long time. It is probable that during
+the Cretaceous time, in some land where we have not yet had a chance
+to study the rocks, these creatures grew to their varied forms, and
+that in the beginning of the Tertiary time, they spread into the
+regions where we find their bones.
+
+Beginning with the Tertiary time, we find these lower kinsmen of man,
+through whom man came to be. The mammals were marked by much greater
+simplicity and likeness to each other than they now have. There were
+probably no monkeys, no horses, no bulls, no sheep, no goats, no
+seals, no whales, and no bats. All these animals had many-fingered
+feet. There were no cloven feet like those of our bulls, and no solid
+feet as our horses have. Their brains, which by their size give us a
+general idea of the intelligence of the creature, are small; hence we
+conclude that these early mammals were less intelligent than those of
+our day.
+
+It would require volumes to trace the history of the growth of these
+early mammals, and show how they, step by step, came to their present
+higher state. We will take only one of the simplest of these changes,
+which happens to be also the one which we know best. This is the
+change that led to the making of our common horses, which seem to have
+been brought into life on the continent of North America. The most
+singular thing about our horses is that the feet have but one large
+toe or finger, the hoof, the hard covering of which is the nail of
+that extremity. Now it seems hard to turn the weak, five-fingered
+feet of the animals of the lower Tertiary--feet which seem to be
+better fitted for tree-climbing than anything else--into feet such as
+we find in the horse. Yet the change is brought about by easy stages
+that lead the successive creatures from the weak and loose-jointed
+foot of the ancient forms to the solid, single-fingered horse's hoof,
+which is wonderfully well-fitted for carrying a large beast at a swift
+speed, and is so strong a weapon of defence that an active donkey can
+kill a lion with a well-delivered kick.
+
+[Illustration: FIG. 10. FEET OF TERTIARY MAMMALS.]
+
+The oldest of these creatures that lead to the horses is called
+_Eohippus_ or beginning horse. This fellow had on the forefeet four
+large toes, each with a small hoof and fifth imperfect one, which
+answered to the thumb. The hind feet had gone further in the change,
+for they each had but three toes, each with hoofs, the middle-toed
+hoof larger and longer than the others. A little later toward our day
+we find another advance in the _Orohippus_, when the little imperfect
+thumb has disappeared, and there are only four toes on the forefeet
+and three on the hind.
+
+Yet later we have the _Mesohippus_ or half-way horse. There are still
+three toes on the hind foot, but one more of the fingers of the
+forefeet has disappeared. This time it is the little finger that goes,
+leaving only a small bone to show that its going was by a slow
+shrinking. The creature now has three little hoofs on each of its
+feet.
+
+Still nearer our own time comes the _Miohippus_, which shows the two
+side hoofs on each foot shrinking up so that they do not touch the
+ground, but they still bear little hoofs. Lastly, about the time of
+man's coming on the earth, appears his faithful servant, the horse, in
+which those little side hoofs have disappeared, leaving only two
+little "splint" bones to mark the place where these side hoofs belong.
+Thus, step by step, our horses' feet were built up; while these parts
+were changing, the other parts of the animals were also slowly
+altering. They were at first smaller than our horses,--some of them
+not as large as an ordinary Newfoundland dog; others as small as
+foxes.
+
+[Illustration: FIG. 11. DEVELOPMENT OF HORSES'S FOOT.]
+
+As if to remind us of his old shape, our horses now and then, but
+rarely, have, in place of the little splint bones above the hoof, two
+smaller hoofs, just like the foot of _Miohippus_. Sometimes these are
+about the size of a silver dollar, on the part that receives the shoe
+when horses are shod.
+
+In this way, by slow-made changes, the early mammals pass into the
+higher. Out of one original part are made limbs as different as the
+feet of the horse, the wing of a bat, the paddle of a whale, and the
+hand of man. So with all the parts of the body the forms change to
+meet the different uses to which they are put.
+
+At the end of this long promise, which was written in the very first
+animals, comes man himself, in form closely akin to the lower animals,
+but in mind immeasurably apart from them. We can find every part of
+man's body in a little different shape in the monkeys, but his mind is
+of a very different quality. While his lower kindred cannot be made to
+advance in intelligence any more than man himself can grow a horse's
+foot or a bat's wing, he is constantly going higher and higher in his
+mental and moral growth.
+
+So far we have found but few traces of man that lead us to suppose
+that he has been for a long geological time on the earth, yet there is
+good evidence that he has been here for a hundred thousand years or
+more. It seems pretty clear that he has changed little in his body in
+all these thousands of generations. The earliest remains show us a
+large-brained creature, who used tools and probably had already made a
+servant of fire, which so admirably aids him in his work.
+
+Besides the development of this wonderful series of animals, that we
+may call in a certain way our kindred, there have been several other
+remarkable advances in this Tertiary time, this age of crowning
+wonders in the earth's history. The birds have gone forward very
+rapidly; it is likely that there were no songsters at the first part
+of this period, but these singing birds have developed very rapidly in
+later times. Among the insects the most remarkable growth is among the
+ants, the bees, and their kindred. These creatures have very wonderful
+habits; they combine together for the making of what we may call
+states, they care for their young, they wage great battles, they keep
+slaves, they domesticate other insects, and in many ways their acts
+resemble the doings of man. Coming at about the same time as man,
+these intellectual insects help to mark this later stage of the earth
+as the intellectual period in its history. Now for the first time
+creatures are on the earth which can form societies and help each
+other in the difficult work of living.
+
+Among the mollusks, the most important change is in the creation of
+the great, strong swimming squids, the most remarkable creatures of
+the sea. Some of these have arms that can stretch for fifty feet from
+tip to tip.
+
+Among the plants, the most important change has been in the growth of
+flowering plants, which have been constantly becoming more plenty, and
+the plants which bear fruits have also become more numerous. The
+broad-leaved trees seem to be constantly gaining on the forests of
+narrow-leaved cone-bearers, which had in an earlier day replaced the
+forests of ferns.
+
+In these Tertiary ages, as in the preceding times of the earth, the
+lands and seas were much changed in their shape. It seems that in the
+earlier ages the land had been mostly in the shape of large islands
+grouped close together where the continents now are. In this time,
+these islands grew together to form the united lands of Europe, Asia,
+Africa, Australia, and the twin American continents; so that, as life
+rose higher, the earth was better fitted for it. Still there were
+great troubles that it had to undergo. There were at least two
+different times during the Tertiary age termed glacial periods, times
+when the ice covered a large part of the northern continents,
+compelling life of all sorts to abandon great regions, and to find new
+places in more southern lands. Many kinds of animals and plants seem
+to have been destroyed in these journeys; but these times of trial, by
+removing the weaker and less competent creatures, made room for new
+forms to rise in their places. All advance in nature makes death
+necessary, and this must come to races as well as to individuals if
+the life of the world is to go onward and upward.
+
+Looking back into the darkened past, of which we yet know but little
+compared with what we would like to know, we can see the great armies
+of living beings led onward from victory to victory toward the higher
+life of our own time. Each age sees some advance, though death
+overtakes all its creatures. Those that escape their actual enemies or
+accident, fall a prey to old age: volcanoes, earthquakes, glacial
+periods, and a host of other violent accidents sweep away the life of
+wide regions, yet the host moves on under a control that lies beyond
+the knowledge of science. Man finds himself here as the crowning
+victory of this long war. For him all this life appears to have
+striven. In his hands lies the profit of all its toil and pain.
+Surely this should make us feel that our duty to all these living
+things, that have shared in the struggle that has given man his
+elevation, is great, but above all, great is our duty to the powers
+that have been placed in our bodies and our minds.
+
+[Illustration: A GLACIER.]
+
+
+
+
+THE PITCH LAKE IN THE WEST INDIES
+
+(FROM AT LAST.)
+
+BY C. KINGSLEY.
+
+
+[Illustration: COOLIE AND NEGRO.]
+
+The Pitch Lake, like most other things, owes its appearance on the
+surface to no convulsion or vagary at all, but to a most slow,
+orderly, and respectable process of nature, by which buried vegetable
+matter, which would have become peat, and finally brown coal, in a
+temperate climate, becomes, under the hot tropic soil, asphalt and
+oil, continually oozing up beneath the pressure of the strata above
+it....
+
+       *       *       *       *       *
+
+As we neared the shore, we perceived that the beach was black with
+pitch; and the breeze being off the land, the asphalt smell (not
+unpleasant) came off to welcome us. We rowed in, and saw in front of a
+little row of wooden houses a tall mulatto, in blue policeman's dress,
+gesticulating and shouting to us. He was the ward policeman, and I
+found him (as I did all the colored police) able and courteous, shrewd
+and trusty. These police are excellent specimens of what can be made
+of the negro, or half-negro, if he be but first drilled, and then
+given a responsibility which calls out his self-respect. He was
+warning our crew not to run aground on one or other of the pitch
+reefs, which here take the place of rocks. A large one, a hundred
+yards off on the left, has been almost all dug away, and carried to
+New York or to Paris to make asphalt-pavement.
+
+[Illustration: THE POLICE STATION.]
+
+The boat was run ashore, under his directions, on a spit of sand
+between the pitch; and when she ceased bumping up and down in the
+muddy surf, we scrambled out into a world exactly the hue of its
+inhabitants of every shade, from jet black to copper-brown. The
+pebbles on the shore were pitch. A tide-pool close by was enclosed in
+pitch; a four-eyes was swimming about in it, staring up at us; and
+when we hunted him, tried to escape, not by diving, but by jumping on
+shore on the pitch, and scrambling off between our legs. While the
+policeman, after profoundest courtesies, was gone to get a mule-cart
+to take us up to the lake, and planks to bridge its water channels,
+we took a look round at this oddest of corners of the earth.
+
+In front of us was the unit of civilization,--the police-station,
+wooden, on wooden stilts (as all well-built houses are here), to
+insure a draught of air beneath them. We were, of course, asked to
+come in and sit down, but preferred looking about, under our
+umbrellas; for the heat was intense. The soil is half pitch, half
+brown earth, among which the pitch sweals in and out as tallow sweals
+from a candle. It is always in slow motion under the heat of the
+tropic sun; and no wonder if some of the cottages have sunk right and
+left in such a treacherous foundation. A stone or brick house could
+not stand here; but wood and palm-thatch are both light and tough
+enough to be safe, let the ground give way as it will.
+
+The soil, however, is very rich. The pitch certainly does not injure
+vegetation, though plants will not grow actually in it. The first
+plants which caught our eyes were pine-apples, for which La Brea is
+famous. The heat of the soil, as well as the air, brings them to
+special perfection. They grow about anywhere, unprotected by hedge or
+fence; for the negroes here seem honest enough, at least toward each
+other; and at the corner of the house was a bush worth looking at, for
+we had heard of it for many a year. It bore prickly, heart-shaped pods
+an inch long, filled with seeds coated with a red waxy pulp.
+
+This was a famous plant--_Bixa orellana Roucou_; and that pulp was the
+well-known annotto dye of commerce. In England and Holland it is used
+merely, I believe, to color cheeses, but in the Spanish Main to color
+human beings. The Indian of the Orinoco prefers paint to clothes; and
+when he has "roucoued" himself from head to foot, considers himself in
+full dress, whether for war or dancing. Doubtless he knows his own
+business best from long experience. Indeed, as we stood broiling on
+the shore, we began somewhat to regret that European manners and
+customs prevented our adopting the Guaraon and Arrawak fashion.
+
+[Illustration: THE MULE-CART.]
+
+The mule-cart arrived; the lady of the party was put into it on a
+chair, and slowly bumped and rattled past the corner of Dundonald
+Street--so named after the old sea-hero, who was, in his life-time,
+full of projects for utilizing this same pitch--and up in pitch road,
+with a pitch gutter on each side.
+
+The pitch in the road has been, most of it, laid down by hand, and is
+slowly working down the slight incline, leaving pools and ruts full of
+water, often invisible, because covered with a film of brown
+pitch-dust, and so letting in the unwary walker over his shoes. The
+pitch in the gutter-bank is in its native place, and as it spues
+slowly out of the soil into the ditch in odd wreaths and lumps, we
+could watch, in little, the process which has produced the whole
+deposit--probably the whole lake itself.
+
+A bullock-cart, laden with pitch, came jolting down past us, and we
+observed that the lumps, when the fracture is fresh, have all a drawn
+out look; that the very air bubbles in them, which are often very
+numerous, are all drawn out likewise, long and oval, like the
+air-bubbles in some ductile lavas.
+
+On our left, as we went on, the bush was low, all of yellow cassia and
+white Hibiscus, and tangled with lovely convolvulus-like creepers,
+Ipomoea and Echites, with white, purple or yellow flowers. On the
+right were negro huts and gardens, fewer and fewer as we went on,--all
+rich with fruit trees, especially with oranges, hung with fruit of
+every hue; and beneath them, of course, the pine-apples of La Brea.
+Everywhere along the road grew, seemingly wild here, that pretty low
+tree, Cashew, with rounded yellow-veined leaves and little green
+flowers, followed by a quaint pink and red-striped pear, from which
+hangs, at the larger and lower end, a kidney-shaped bean, which bold
+folk eat when roasted; but woe to those who try it when raw; for the
+acrid oil blisters the lips, and even while the beans are roasting the
+fumes of the oil will blister the cook's face if she holds it too near
+the fire.
+
+As we went onward up the gentle slope (the rise is one hundred and
+thirty-eight feet in rather more than a mile), the ground became more
+and more full of pitch, and the vegetation poorer and more rushy,
+till it resembled, on the whole, that of an English fen. An Ipomoea or
+two, and a scarlet flowered dwarf Heliconia, kept up the tropic type,
+as does a stiff brittle fern about two feet high. We picked the weeds,
+which looked like English mint or basil, and found that most of them
+had three longitudinal nerves in each leaf, and were really
+Melastomas, though dwarfed into a far meaner habit than that of the
+noble forms we saw at Chaguanas, and again on the other side of the
+lake. On the right, too, in a hollow, was a whole wood of Groogroo
+palms, gray stemmed, gray leaved, and here and there a patch of white
+or black Roseau rose gracefully eight or ten feet high among the
+reeds.
+
+The plateau of pitch now widened out, and the whole ground looked like
+an asphalt pavement, half overgrown with marsh-loving weeds, whose
+roots feed in the sloppy water which overlies the pitch. But, as yet,
+there was no sign of the lake. The incline, though gentle, shuts off
+the view of what is beyond. This last lip of the lake has surely
+overflowed, and is overflowing still, though very slowly. Its furrows
+all curve downward; and it is, in fact, as one of our party said, "a
+black glacier." The pitch, expanding under the burning sun of day,
+must needs expand most toward the line of least resistance--that is,
+downhill; and when it contracts again under the coolness of night, it
+contracts, surely, from the same cause, more downhill than uphill; and
+so each particle never returns to the spot whence it started, but
+rather drags the particles above it downward toward itself. At least,
+so it seemed to us. Thus may be explained the common mistake which is
+noticed by Messrs. Wall and Sawkins in their admirable description of
+the lake.
+
+"All previous descriptions refer the bituminous matter scattered over
+the La Brea district, and especially that between the village and the
+lake, to streams which have issued at some former epoch from the lake,
+and extended into the sea. This supposition is totally incorrect, as
+solidification would probably have ensued before it had proceeded
+one-tenth of the distance; and such of the asphalt as has undoubtedly
+escaped from the lake has not advanced more than a few yards, and
+always presents the curved surfaces already described, and never
+appears as an extended sheet."
+
+Agreeing with this statement as a whole, I nevertheless cannot but
+think it probable that a great deal of the asphalt, whether it be in
+large masses or in scattered veins, may be moving very slowly down
+hill, from the lake to the sea, by the process of expansion by day and
+contraction by night, and may be likened to a caterpillar, or rather
+caterpillars innumerable, progressing by expanding and contracting
+their rings, having strength enough to crawl down hill, but not
+strength enough to back up hill again.
+
+At last we surmounted the last rise, and before us lay the famous
+lake--not at the bottom of a depression, as we expected, but at the
+top of a rise, whence the ground slopes away from it on two sides, and
+rises from it very slightly on the two others. The black pool glared
+and glittered in the sun. A group of islands, some twenty yards wide,
+were scattered about the middle of it. Beyond it rose a double forest
+of Moriche fan-palms; and to the right of them high wood with giant
+Mombins and undergrowth of Cocorite--a paradise on the other side of
+the Stygian pool.
+
+[Illustration: THE PITCH LAKE.]
+
+We walked, with some misgivings, on to the asphalt, and found it
+perfectly hard. In a few steps we were stopped by a channel of clear
+water, with tiny fish and water-beetles in it; and, looking round, saw
+that the whole lake was intersected with channels, so unlike anything
+which can be seen elsewhere that it is not easy to describe them.
+
+Conceive a crowd of mushrooms, of all shapes, from ten to fifty feet
+across, close together side by side, their tops being kept at exactly
+the same level, their rounded rims squeezed tight against each other;
+then conceive water poured on them so as to fill the parting seams,
+and in the wet season, during which we visited it, to overflow the
+tops somewhat. Thus would each mushroom represent, tolerably well, one
+of the innumerable flat asphalt bosses, which seem to have sprung up
+each from a separate centre, while the parting seams would be of much
+the same shape as those in the asphalt, broad and shallow atop, and
+rolling downward in a smooth curve, till they are at bottom mere
+cracks from two to ten feet deep. Whether these cracks actually close
+up below, and the two contiguous masses of pitch become one, cannot be
+seen. As far as the eye goes down, they are two, though pressed close
+to each other. Messrs. Wall and Sawkins explain the odd fact clearly
+and simply. The oil, they say, which the asphalt contains when it
+rises first, evaporates in the sun, of course most on the outside of
+the heap, leaving a thorough coat of asphalt, which has, generally, no
+power to unite with the corresponding coat of the next mass. Meanwhile
+Mr. Manross, an American gentleman, who has written a very clever and
+interesting account of the lake, seems to have been so far deceived by
+the curved and squeezed edges of these masses that he attributes to
+each of them a revolving motion, and supposes that the material is
+continually passing from the centre to the edges, when it "rolls
+under," and rises again in the middle. Certainly the strange stuff
+looks, at the first glance, as if it were behaving in this way; and
+certainly, also, his theory would explain the appearance of sticks and
+logs in the pitch. But Messrs. Wall and Sawkins say that they have
+observed no such motion: nor did we; and I agree with them, that it is
+not very obvious to what force, or what influence, it could be
+attributable. We must, therefore, seek some other way of accounting
+for the sticks--which utterly puzzled us, and which Mr. Manross well
+describes as "numerous pieces of wood, which, being involved in the
+pitch, are constantly coming to the surface. They are often several
+feet in length, and five or six inches in diameter. On reaching the
+surface they generally assume an upright position, one end being
+detained in the pitch, while the other is elevated by the lifting of
+the middle. They may be seen at frequent intervals over the lake,
+standing up to the height of two or even three feet. They look like
+stumps of trees protruding through the pitch; but their parvenu
+character is curiously betrayed by a ragged cap of pitch which
+invariably covers the top, and hangs down like hounds' ears on either
+side."
+
+Whence do they come? Have they been blown on to the lake, or left
+behind by man? or are they fossil trees, integral parts of the
+vegetable stratum below which is continually rolling upward? or are
+they of both kinds? I do not know. Only this is certain, as Messrs.
+Wall and Sawkins have pointed out, that not only "the purer varieties
+of asphalt, such as approach or are identical with asphalt glance,
+have been observed" (though not, I think, in the lake itself) "in
+isolated masses, where there was little doubt of their proceeding from
+ligneous substances of larger dimensions, such as roots and pieces of
+trunks and branches," but, moreover, that "it is also necessary to
+admit a species of conversion by contact, since pieces of wood
+included accidentally in the asphalt, for example, by dropping from
+overhanging vegetation, are often found partially transformed into the
+material." This is a statement which we verified again and again, as
+we did the one which follows, namely, that the hollow bubbles which
+abound on the surface of the pitch "generally contain traces of the
+lighter portion of vegetation," and "are manifestly derived from
+leaves, etc., which are blown about the lake by the wind, and are
+covered with asphalt, and, as they become asphalt themselves, give off
+gases which form bubbles round them."
+
+But how is it that those logs stand up out of the asphalt, with
+asphalt caps and hounds' ears (as Mr. Manross well phrases it) on the
+tops of them?
+
+We pushed on across the lake, over the planks which the negroes laid
+down from island to island. Some, meanwhile, preferred a steeple-chase
+with water-jumps, after the fashion of the midshipmen on a certain
+second visit to the lake. How the negroes grinned delight and surprise
+at the vagaries of English lads--a species of animal altogether new to
+them; and how they grinned still more when certain staid and portly
+dignitaries caught the infection, and proved by more than one good
+leap that they too had been English school-boys--alas! long, long ago.
+
+So, whether by bridging, leaping, or wading, we arrived at the little
+islands, and found them covered with a thick, low scrub; deep sedge,
+and among them Pinguins, like huge pine-apples without the apple; gray
+wild-pines, parasites on Matapalos, which, of course, have established
+themselves, like robbers and vagrants as they are, everywhere; a true
+holly, with box-like leaves; and a rare cocoa-plum, very like the
+holly in habit, which seems to be all but confined to these little
+patches of red earth, afloat on the pitch. Out of the scrub, when we
+were there, flew off two or three night-jars, very like our English
+species, save that they had white in the wings; and on the second
+visit one of the midshipmen, true to the English boy's bird's-nesting
+instinct, found one of their eggs, white-spotted, in a grass nest.
+
+Passing these little islands, which are said (I know not how truly) to
+change their places and number, we came to the very fountains of Styx,
+to that part of the lake where the asphalt is still oozing up.
+
+As the wind set toward us, we soon became aware of an evil
+smell--petroleum and sulphureted hydrogen at once--which gave some of
+us a headache. The pitch here is yellow and white with sulphur foam;
+so are the water-channels; and out of both water and pitch innumerable
+bubbles of gas arise, loathsome to the smell. We became aware that the
+pitch was soft under our feet. We left the impression of our boots;
+and if we had stood still awhile, we should soon have been ankle-deep.
+No doubt there are spots where, if a man stayed long enough, he would
+be slowly and horribly engulfed. "But," as Mr. Manross says truly, "in
+no place is it possible to form those bowl-like depressions round the
+observer described by former travellers." What we did see is that the
+fresh pitch oozes out at the lines of least resistance, namely, in the
+channels between the older and more hardened masses, usually at the
+upper ends of them, so that one may stand on pitch comparatively hard,
+and put one's hand into pitch quite liquid, which is flowing softly
+out, like some ugly fungoid growth, such as may be seen in old
+wine-cellars, into the water. One such pitch-fungus had grown several
+yards in length in the three weeks between our first and second visit;
+and on another, some of our party performed exactly the same feat as
+Mr. Manross.
+
+"In one of the star-shaped pools of water, some five feet deep, a
+column of pitch had been forced perpendicularly up from the bottom. On
+reaching the surface of the water it had formed a sort of
+centre-table, about four feet in diameter, but without touching the
+sides of the pool. The stem was about a foot in diameter. I leaped out
+on this table, and found that it not only sustained my weight, but
+that the elasticity of the stem enabled me to rock it from side to
+side. Pieces torn from the edges of this table sank readily, showing
+that it had been raised by pressure, and not by its buoyancy."
+
+True, though strange; but stranger still did it seem to us when we did
+at last what the negroes asked us, and dipped our hands into the
+liquid pitch, to find that it did not soil the fingers. The old
+proverb that one cannot touch pitch without being defiled happily does
+not stand true here, or the place would be intolerably loathsome. It
+can be scraped up, moulded into any shape you will, wound in a string
+(as was done by one of the midshipmen) round a stick, and carried off;
+but nothing is left on the hand save clean gray mud and water. It may
+be kneaded for an hour before the mud be sufficiently driven out of it
+to make it sticky. This very abundance of earthy matter it is which,
+while it keeps the pitch from soiling, makes it far less valuable than
+it would be were it pure.
+
+It is easy to understand whence this earthy matter (twenty or thirty
+per cent) comes. Throughout the neighborhood the ground is full, to
+the depth of hundreds of feet, of coaly and asphaltic matter. Layers
+of sandstone or of shale containing this decayed vegetable alternate
+with layers which contain none; and if, as seems probable, the coaly
+matter is continually changing into asphalt and oil, and then working
+its way upward through every crack and pore, to escape from the
+enormous pressure of the superincumbent soil, it must needs carry up
+with it innumerable particles of the soils through which it passes.
+
+In five minutes we had seen, handled, and smelt enough to satisfy us
+with this very odd and very nasty vagary of tropic nature; and as we
+did not wish to become faint and ill between the sulphureted hydrogen
+and the blaze of the sun reflected off the hot black pitch, we hurried
+on over the water-furrows, and through the sedge-beds to the farther
+shore--to find ourselves, in a single step, out of an Inferno into a
+Paradise.
+
+[Illustration]
+
+
+
+
+A STALAGMITE CAVE
+
+(FROM THE VOYAGE OF THE CHALLENGER.)
+
+BY SIR C. WYVILLE THOMSON, KT., LL.D., ETC.
+
+
+[Illustration]
+
+I think the Painter's Vale cave is the prettiest of the whole. The
+opening is not very large. It is an arch over a great mass of débris
+forming a steep slope into the cave, as if part of the roof of the
+vault had suddenly fallen in. At the foot of the bank of débris one
+can barely see in the dim light the deep clear water lying perfectly
+still and reflecting the roof and margin like a mirror. We clambered
+down the slope, and as the eye became more accustomed to the obscurity
+the lake stretched further back. There was a crazy little punt moored
+to the shore, and after lighting candles Captain Nares rowed the
+Governor back into the darkness, the candles throwing a dim light for
+a time--while the voices became more hollow and distant--upon the
+surface of the water and the vault of stalactite, and finally passing
+back as mere specks into the silence.
+
+[Illustration: A GUIDE.]
+
+After landing the Governor on the opposite side, Captain Nares
+returned for me, and we rowed round the weird little lake. It was
+certainly very curious and beautiful; evidently a huge cavity out of
+which the calcareous sand had been washed or dissolved, and whose
+walls, still to a certain extent permeable, had been hardened and
+petrified by the constant percolation of water charged with carbonate
+of lime. From the roof innumerable stalactites, perfectly white, often
+several yards long and coming down to the delicacy of knitting-needles,
+hung in clusters; and wherever there was any continuous crack in the
+roof or wall, a graceful, soft-looking curtain of white stalactite
+fell, and often ended, much to our surprise. Deep in the water
+Stalagmites also rose up in pinnacles and fringes through the water,
+which was so exquisitely still and clear that it was something
+difficult to tell where the solid marble tracery ended, and its
+reflected image began. In this cave, which is a considerable distance
+from the sea, there is a slight change of level with the tide
+sufficient to keep the water perfectly pure. The mouth of the cave is
+overgrown with foliage, and every tree is draped and festooned with
+the fragrant _Jasminum gracile_, mingled not unfrequently with the
+"poison ivy" (_Rhus toxicodendron_). The Bermudians, especially the
+dark people, have a most exaggerated horror of this bush. They imagine
+that if one touch it or rub against it he becomes feverish, and is
+covered with an eruption. This is no doubt entirely mythical. The
+plant is very poisonous, but the perfume of the flower is rather
+agreeable, and we constantly plucked and smelt it without its
+producing any unpleasant effect. The tide was with us when we regained
+the Flats Bridge, and the galley shot down the rapid like an arrow,
+the beds of scarlet sponges and the great lazy trepangs showing
+perfectly clearly on the bottom at a fathom depth.
+
+[Illustration: FIG. 1. CALCAREOUS CONCRETION SIMULATING A FOSSIL
+PALM-STEM, BOAZ ISLAND, BERMUDAS.]
+
+Every here and there throughout the islands there are groups of bodies
+of very peculiar form projecting from the surface of the limestone
+where it has been weathered. These have usually been regarded as
+fossil palmetto stumps, the roots of trees which have been overwhelmed
+with sand and whose organic matter has been entirely removed and
+replaced by carbonate of lime. Fig. 1 represents one of the most
+characteristic of these from a group on the side of the road in Boaz
+Island. It is a cylinder a foot in diameter and six inches or so high;
+the upper surface forms a shallow depression an inch deep surrounded
+by a raised border; the bottom of the cup is even, and pitted over
+with small depressions like the marks of rain-drops on sand; the walls
+of the cylinder seem to end a few inches below the surface of the
+limestone in a rounded boss, and all over this there are round
+markings or little cylindrical projections like the origins of
+rootlets. The object certainly appears to agree even in every detail
+with a fossil palm-root, and as the palmetto is abundant on the
+islands and is constantly liable to be destroyed by and ultimately
+enveloped in a mass of moving sand, it seemed almost unreasonable to
+question its being one. Still something about the look of these things
+made me doubt, with General Nelson, whether they were fossil palms, or
+indeed whether they were of organic origin at all; and after carefully
+examining and pondering over several groups of them, at Boaz Island,
+on the shore at Mount Langton, and elsewhere, I finally came to the
+conclusion that they were not fossils, but something totally
+different.
+
+[Illustration: FIG. 2. CALCAREOUS CONCRETION IN AEOLIAN LIMESTONE,
+BERMUDAS.]
+
+[Illustration: FIG. 3. CALCAREOUS CONCRETION IN AEOLIAN LIMESTONE,
+BERMUDAS.]
+
+[Illustration: FIG. 4. CALCAREOUS CONCRETION, BERMUDAS.]
+
+[Illustration: FIG. 5. CALCAREOUS CONCRETION IN AEOLIAN LIMESTONE,
+BERMUDAS.]
+
+The form given in Fig. 1 is the most characteristic, and probably by
+far the most common; but very frequently one of a group of these, one
+which is evidently essentially the same as the rest and formed in the
+same way, has an oval or an irregular shape (Figs. 2, 3, and 4). In
+these we have the same raised border, the same scars on the outside,
+the same origins of root-like fibres, and the same pitting of the
+bottom of the shallow cup; but their form precludes the possibility of
+their being tree-roots. In some cases (Fig. 5), a group of so-called
+"palm-stems" is inclosed in a space surrounded by a ridge, and on
+examining it closely this outer ridge is found to show the same
+leaf-scars and traces of rootlets as the "palm-stems" themselves. In
+some cases very irregular honey-combed figures are produced which the
+examination of a long series of intermediate forms shows to belong to
+the same category (Fig. 6).
+
+[Illustration: FIG. 6. CONCRETIONS IN AEOLIAN ROCKS, BERMUDAS.]
+
+In the caves in the limestone, owing to a thread of water having found
+its way in a particular direction through the porous stone of the
+roof, a drop falls age after age on one spot on the cave-floor,
+accurately directed by the stalactite which it is all the time
+creating. The water contains a certain proportion of carbonate of
+lime, which is deposited as stalagmite as the water evaporates, and
+thus a ring-like crust is produced at a little distance from the spot
+where the drop falls. When a ring is once formed, it limits the spread
+of the drop, and determines the position of the wall bounding the
+little pool made by the drop. The floor of the cave gradually rises by
+the accumulation of sand and travertine, and with it rise the walls
+and floor of the cup by the deposit of successive layers of stalagmite
+produced by the drop percolating into the limestone of the floor which
+hardens it still further, but in this peculiar symmetrical way. From
+the floor and sides of the cup the water oozes into the softer
+limestone around and beneath; but, as in all these limestones, it does
+not ooze indiscriminately, but follows certain more free paths. These
+become soon lined and finally blocked with stalagmite, and it is
+these tubes and threads of stalagmite which afterwards in the
+pseudo-fossil represent the diverging rootlets.
+
+[Illustration: A STALAGMITE CAVE.]
+
+Sometimes when two or more drops fall from stalactites close to one
+another the cups coalesce (Figs. 2, 3, and 4); sometimes one drop or
+two is more frequent than the other, and then we have the form shown
+in Figs. 3 and 4; sometimes many drops irregularly scattered form a
+large pool with its raised border, and a few drops more frequent and
+more constant than the rest grow their "palmetto stems" within its
+limit (Fig. 5); and sometimes a number of drops near one another make
+a curious regular pattern, with the partitions between the recesses
+quite straight (Fig. 6).
+
+I have already referred to the rapid denudation which is going on in
+these islands, and to the extent to which they have been denuded
+within comparatively recent times. The floors of caves, from their
+being cemented into a nearly homogeneous mass by stalagmitic matter,
+are much harder than the ordinary porous blown limestone; and it seems
+that in many cases, after the rocks forming the walls and roof have
+been removed, disintegration has been at all events temporarily
+arrested by the floor. Where there is a flat surface of rock exposed
+anywhere on the island, it very generally bears traces of having been
+at one time the floor of a cave; and as the weather-wearing of the
+surface goes on, the old concretionary structures are gradually
+brought out again, the parts specially hardened by a localized slow
+infiltration of lime resist integration longest and project above the
+general surface. Often a surface of weathered rock is so studded with
+these symmetrical concretions, that it is hard to believe that one is
+not looking at the calcified stumps of a close-growing grove of palms.
+
+[Illustration]
+
+
+
+
+THE BIG TREES OF CALIFORNIA
+
+(FROM STUDIES SCIENTIFIC AND SOCIAL.)
+
+BY ALFRED RUSSEL WALLACE.
+
+
+[Illustration]
+
+In the popular accounts of these trees it is usual to dwell only on
+the dimensions of the very largest known specimens, and sometimes even
+to exaggerate these. Even the smaller full-grown trees, however, are
+of grand dimensions, varying from fourteen to eighteen feet in
+diameter, at six feet above the ground, and keeping nearly the same
+thickness for perhaps a hundred feet. In the south Calaveras grove,
+where there are more than a thousand trees, the exquisite beauty of
+the trunks is well displayed by the numerous specimens in perfect
+health and vigor. The bark of these trees, seen at a little distance,
+is of a bright orange brown tint, delicately mottled with darker
+shades, and with a curious silky or plush-like gloss, which gives them
+a richness of color far beyond that of any other conifer. The tree
+which was cut down soon after the first discovery of the species, the
+stump of which is now covered with a pavilion, is twenty-five feet in
+diameter at six feet above the ground, but this is without the thick
+bark, which would bring it to twenty-seven feet when alive. A
+considerable portion of this tree still lies where it fell, and at one
+hundred and thirty feet from the base I found it to be still twelve
+and a half feet in diameter (or fourteen feet with the bark), while at
+the extremity of the last piece remaining, two hundred and fifteen
+feet from its base, it is six feet in diameter, or at least seven feet
+with the bark. The height of this tree when it was cut down is not
+recorded, but as one of the living trees is more than three hundred
+and sixty feet high, it is probable that this giant was not much short
+of four hundred feet.
+
+[Illustration: THE "MOTHER OF THE FOREST."]
+
+In the accompanying picture the dead tree in the centre is that from
+which the bark was stripped, which was erected in the Crystal Palace
+and unfortunately destroyed by fire. It is called the "Mother of the
+Forest." The two trees nearer the foreground are healthy, medium-sized
+trees, about fifteen feet diameter at six feet above the ground.
+
+The huge decayed trunk called "Father of the Forest," which has fallen
+perhaps a century or more, exhibits the grandest dimensions of any
+known tree. By measuring its remains, and allowing for the probable
+thickness of the bark, it seems to have been about thirty-five feet
+diameter near the ground, at ninety feet up fifteen feet, and even at
+a height of two hundred and seventy feet, it was nine feet in
+diameter. It is within the hollow trunk of this tree that a man on
+horse-back can ride--both man and horse being rather small; but the
+dimensions undoubtedly show that it was considerably larger than the
+"Pavilion tree," and that it carried its huge dimensions to a greater
+altitude; and although this does not prove it to have been much
+taller, yet it was in all probability more than four hundred feet in
+height.
+
+[Illustration]
+
+Very absurd statements are made to visitors as to the antiquity of
+these trees, three or four thousand years being usually given as their
+age. This is founded on the fact that while many of the large Sequoias
+are greatly damaged by fire, the large pines and firs around them are
+quite uninjured. As many of these pines are assumed to be near a
+thousand years old, the epoch of the "great fire" is supposed to be
+earlier still, and as the Sequoias have not outgrown the fire-scars in
+all that time, they are supposed to have then arrived at their full
+growth. But the simple explanation of these trees alone having
+suffered so much from fire is, that their bark is unusually thick,
+dry, soft, and fibrous, and it thus catches fire more easily and
+burns more readily and for a longer time than that of the other
+coniferæ. Forest fires occur continually, and the visible damage done
+to these trees has probably all occurred in the present century.
+Professor C.B. Bradley, of the University of California, has carefully
+counted the rings of annual growth on the stump of the "Pavilion
+tree," and found them to be twelve hundred and forty; and after
+considering all that has been alleged as to the uncertainty of this
+mode of estimating the age of a tree, he believes that in the climate
+of California, in the zone of altitude where these trees grow, the
+seasons of growth and repose are so strongly marked that the number of
+annual rings gives an accurate result.
+
+Other points that have been studied by Professor Bradley are, the
+reason why there are so few young trees in the groves, and what is the
+cause of the destruction of the old trees. To take the last point
+first, these noble trees seem to be singularly free from disease or
+from decay due to old age. All the trees that have been cut down are
+solid to the heart, and none of the standing trees show any
+indications of natural decay. The only apparent cause for their
+overthrow is the wind, and by noting the direction of a large number
+of fallen trees it is found that the great majority of them lie more
+or less towards the south. This is not the direction of the prevalent
+winds, but many of the tallest trees lean towards the south, owing to
+the increased growth of their topmost branches towards the sun. They
+are then acted upon by violent gales, which loosen their roots, and
+whatever the direction of the wind that finally overthrows them, they
+fall in the direction of the over-balancing top weight. The young
+trees grow spiry and perfectly upright, but as soon as they overtop
+the surrounding trees and get the full influence of the sun and wind,
+the highest branches grow out laterally, killing those beneath their
+shade, and thus a dome-shaped top is produced. Taking into
+consideration the health and vigor of the largest trees, it seems
+probable that, under favorable conditions of shelter from violent
+winds, and from a number of trees around them of nearly equal height,
+big trees might be produced far surpassing in height and bulk any that
+have yet been discovered. It is to be hoped that if any such are found
+to exist in the extensive groves of these trees to the south of those
+which are alone accessible to tourists, the Californian Government
+will take steps to reserve a considerable tract containing them, for
+the instruction and delight of future generations.
+
+The scarcity of young Sequoias strikes every visitor, the fact being
+that they are only to be found in certain favored spots. These are,
+either where the loose débris of leaves and branches which covers the
+ground has been cleared away by fire, or on the spots where trees have
+been uprooted. Here the young trees grow in abundance, and serve to
+replace those that fall. The explanation of this is, that during the
+long summer drought the loose surface débris is so dried up that the
+roots of the seedling Sequoias perish before they can penetrate the
+earth beneath. They require to germinate on the soil itself, and this
+they are enabled to do when the earth is turned up by the fall of a
+tree, or where a fire has cleared off the débris. They also flourish
+under the shade of the huge fallen trunks in hollow places, where
+moisture is preserved throughout the summer. Most of the other
+conifers of these forests, especially the pines, have much larger
+seeds than the Sequoias, and the store of nourishment in these more
+bulky seeds enables the young plants to tide over the first summer's
+drought. It is clear, therefore, that there are no indications of
+natural decay in these forest giants. In every stage of their growth
+they are vigorous and healthy, and they have nothing to fear except
+from the destroying hand of man.
+
+[Illustration: REDWOOD TREE WITH TRIPLE TRUNK.]
+
+Destruction from this cause is, however, rapidly diminishing both the
+giant Sequoia and its near ally the noble redwood (_Sequoia
+sempervirens_), a tree which is more beautiful in foliage and in some
+other respects more remarkable than its brother species, while there
+is reason to believe that under favorable conditions it reaches an
+equally phenomenal size. It once covered almost all the coast ranges
+of central and northern California, but has been long since cleared
+away in the vicinity of San Francisco, and greatly diminished
+elsewhere. A grove is preserved for the benefit of tourists near Santa
+Cruz, the largest tree being two hundred and ninety-six feet high,
+twenty-nine feet diameter at the ground and fifteen feet at six feet
+above it. One of these trees having a triple trunk is here figured
+from a photograph. Much larger trees, however, exist in the great
+forests of this tree in the northern part of the State; but these are
+rapidly being destroyed for the timber, which is so good and durable
+as to be in great demand. Hence Californians have a saying that the
+redwood is too good a tree to live. On the mountains a few miles east
+of the Bay of San Francisco, there are a number of patches of young
+redwoods, indicating where large trees have been felled, it being a
+peculiarity of this tree that it sends up vigorous young plants from
+the roots of old ones immediately around the base. Hence in the
+forests these trees often stand in groups arranged nearly in a circle,
+thus marking out the size of the huge trunks of their parents. It is
+from this quality that the tree has been named _sempervirens_, or ever
+flourishing. Dr. Gibbons, of Alameda, who has explored all the remains
+of the redwood forests in the neighborhood of Oakland, kindly took me
+to see the old burnt-out stump of the largest tree he had discovered.
+It is situated about fifteen hundred feet above the sea, and is
+thirty-four feet in diameter at the ground. This is as large as the
+very largest specimens of the _Sequoia gigantea_, but it may have
+spread out more at the base and have been somewhat smaller above,
+though this is not a special characteristic of the species.
+
+[Illustration]
+
+
+
+
+WHAT IS EVOLUTION?
+
+(FROM THE ATLANTIC MONTHLY, MARCH, '93.)
+
+BY PROFESSOR E.S. HOLDEN.
+
+
+[Illustration]
+
+I was once trying to tell a boy, a friend of mine, what the scientific
+men mean by the long word _Evolution_, and to give him some idea of
+the plan of the world. I wanted an illustration of something that had
+grown--evolved, developed--from small beginnings up through more and
+more complicated forms, till it had reached some very complete form. I
+could think of no better example than the railway by which we were
+sitting. The trains were running over the very track where a
+wagon-road had lately been, and before that a country cart-track, and
+before that a bridle-path, and before that again a mere trail for
+cattle. So I took the road for an example, and tried to show my boy
+how it had grown from little things by slow degrees according to laws;
+and if you like, I will try to tell it again.
+
+Just as one can go further and further back, and always find a bird to
+be the parent of the egg, and an egg to be the parent of that bird, so
+in the history of this road of ours; we may go back and back into the
+past, always finding something earlier, which is the cause of the
+something later. The earth, the planets, and the sun were all a fiery
+mist long ago. And in that mist, and in what came before it, we may
+look for the origin of things as they are. But we must begin
+somewhere. Let us begin with the landscape as we see it now,--hills,
+valleys, streams, mountains, grass,--but with only a single tree.
+
+We will not try to say how the tree came there. At least, we will not
+try just yet. When we are through with the story you can say just as
+well as I can.
+
+Suppose, then, a single oak-tree stood just on that hillside thousands
+and thousands of years ago. Grass was growing everywhere, and flowers,
+too. The seeds came with the winds. Year after year the oak-tree bore
+its acorns, hundreds and hundreds of them, and they fell on the grass
+beneath and rolled down the smooth slopes, and sprouted as best they
+could,--most of them uselessly so far as producing trees were
+concerned,--but each one did its duty and furnished its green sprout,
+and died if it found no nourishment.
+
+All the hundreds of acorns rolled down the slopes, Not one rolled up;
+and here was a _law_,--the law of gravitation,--in full activity.
+There were scores of other laws active, too; for evolution had gone a
+long way when we had an earth fit to be lived on, and hills in their
+present shape, and a tree bearing acorns that would reproduce their
+kind. But ever since the fiery mist this simple law of gravitation has
+been acting, binding the whole universe together, making a
+relationship between each clod and every other clod, and forcing
+every stone, every acorn, and every rain-drop to move down and not up.
+
+Just as this law operates,--continuously, silently, inexorably,--so
+every other law makes itself felt in its own sphere. Gravitation is
+simple. The law according to which an acorn makes an oak--and not a
+pine-tree is complex. But the laws of Nature are all alike, and if we
+understand the simple ones, we can at least partly comprehend the more
+complex. They are nothing but fixed habits on a large scale.
+
+So the acorns fell year by year and sprouted; and one out of a
+thousand found good soil, and was not wasted, and made a tree. And so
+all around (below) the tree with which we started there grew a grove
+of oaks like it, in fact its children; and finally the original trees
+died, but not without having left successors.
+
+First of all, the green hillside is smooth and untrodden. There is
+nothing but grass and flowers, borne there by the winds, which leave
+no track. There is no animal life even in this secluded spot save the
+birds, and they too leave no track. By and by there comes a hard
+winter, or a dearth of food, and a pair of stray squirrels emigrate
+from their home in the valley below; and the history of our hill and
+its woods begins. Mere chance decides the choice of the particular
+oak-tree in which the squirrels make their home. From the foot of this
+tree they make excursions here and there for their store of winter
+food,--acorns and the like,--and they leave little paths on the
+hillside from tree to tree.
+
+The best-marked paths run to the places where there are the most
+acorns. A little later on there are more squirrels in the colony,--the
+young of the parent pair, and other colonists from the valley. The
+little tracks become plainer and plainer.
+
+Later still come other wild animals in search of food,--squirrels will
+do. The wild animals do not remain in the colony (there are too few
+squirrels, and they are too hard to catch), but they pass through it,
+sometimes by day but oftenest by night.
+
+You might think it was perfectly a matter of chance along which path a
+bear or a wolf passed, but it was not. He _could_ walk anywhere on the
+hillside; and sometimes he would be found far out of the paths that
+the squirrels had begun. But usually, when he was in no haste, he took
+the easiest path. The easiest one was that which went between the
+bushes and not through them; along the hillside and not straight up
+it; around the big rocks and not over them. The wolves and bears and
+foxes have new and different wants when they come; and they break new
+paths to the springs where they drink, to the shade where they lie, to
+the hollow trees where the bees swarm and store the wild honey.
+
+But the squirrels were the first surveyors of these tracks. The bears
+and wolves are the engineers, who change the early paths to suit their
+special convenience.
+
+By and by the Indian hunter comes to follow the wild game. He, too,
+takes the easiest trail, the path of least resistance; and he follows
+the track to the spring that the deer have made, and he drinks there.
+He is an animal as they are, and he satisfies his animal wants
+according to the same law that governs them.
+
+After generations of hunters, Indians, and then white men, there comes
+a man on horseback looking for a house to live in. He, too, follows
+along the easiest paths and stops at the spring; and near by he finds
+the place he is looking for. Soon he returns, driving before him herds
+of cattle and flocks of sheep, which spread over the grassy glades to
+feed. But everywhere they take the easiest place, the old paths, from
+the shady tree to the flowing spring. After awhile the hillside is
+plainly marked with these sheep trails. You can see them now whenever
+you go into the country, on every hillside.
+
+Soon there are neighbors who build their homes in the next valley, and
+a good path must be made between the different houses.
+
+A few days' work spent in moving the largest stones, in cutting down
+trees, and in levelling off a few steep slopes, makes a trail along
+which you can gallop your horse.
+
+Things move fast now,--history begins to be made quickly as soon as
+man takes a hand in it. Soon the trail is not enough: it must be
+widened so that a wagon-load of boards for a new house can be carried
+in (for the settler has found a wife). After the first cart-track is
+made to carry the boards and shingles in, a better road will be needed
+to haul firewood and grain out (for the wants of the new family have
+increased, and things must be bought in the neighboring village with
+money, and money can only be had by selling the products of the farm).
+By and by the neighborhood is so well inhabited that it is to the
+advantage of the villages all around it to have good and safe and easy
+roads there; and the road is declared a public one, and it is
+regularly kept in repair and improved at the public expense. Do not
+forget the squirrels of long ago. They were the projectors of this
+road. Their successors use it now,--men and squirrels alike,--and stop
+at the spring to drink, and under the huge oaks to rest.
+
+A few years more, and it becomes to the advantage of all to have a
+railway through the valley and over the hillside. Then a young
+surveyor, just graduated from college, comes with his chain-men and
+flag-men, and finds that the squirrels, and bears, and hunters, and
+all the rest have picked out the easiest way for him long centuries
+ago. He makes his map, and soon the chief enigneer and the president
+of the road drive along in a buggy with a pair of fast horses
+(frightening the little squirrels off their road-way and into their
+holes), and the route of the Bear Valley and Quercus Railway is
+finally selected, and here it is. See! there comes a train along the
+track. This is the way a railway route grew out of a squirrel path.
+There are thousands of little steps, but you can trace them, or
+imagine them, as well as I can tell you.
+
+It is the same all over the world. Stanley cut a track through the
+endless African forests. But it lay between the Pygmy villages, along
+the paths they had made, and through the glades where they fought
+their battles with the storks.
+
+Sometimes the first road is a river--the track is already cut. Try to
+find out where the settlements in America were in the very early
+days--before 1800. You will find them along the Hudson, the Juanita,
+the St. Lawrence, the James, the Mississippi Rivers. But when these
+are left, men follow the squirrel-tracks and bear-tracks, or the
+paths of hunters, or the roads of Roman soldiers. It is a standing
+puzzle to little children why all the great rivers flow past the great
+towns. (Why do they?) The answer to that question will tell you why
+the great battles are fought in the same regions; why Egypt has been
+the coveted prize of a dozen different conquerors (it is the gateway
+of the East); why our Civil War turned on the possession of the
+Mississippi River. It is the roadways we fight for, the ways in and
+out, whether they be land or water. Of course, we really fought for
+something better than the mere possession of a roadway, but to get
+what we fought for we had to have the roadway first.
+
+The great principle at the bottom of everything in Nature is that the
+fittest survives: or, as I think it is better to say it, in any
+particular conflict or struggle that thing survives which is the
+fittest to survive _in this particular struggle_. This is Mr. Darwin's
+discovery,--or one of them,--and the struggle for existence is a part
+of the great struggle of the whole universe, and the laws of it make
+up the methods of Evolution--of Development.
+
+It is clear now, is it not, how the railway route is the direct
+descendant of the tiny squirrel track between two oaks? The process of
+development we call Evolution, and you can trace it all around you.
+Why are your skates shaped in a certain way? Why is your gun rifled?
+Why have soldiers two sets of (now) useless buttons on the skirts of
+their coats? (I will give you three guesses for this, and the hint
+that you must think of cavalry soldiers.) Why are eagles' wings of
+just the size that they are? These and millions of like questions are
+to be answered by referring to the principle of development.
+
+Sometimes it is hard to find the clew. Sometimes the development has
+gone so far, and the final product has become so complex and special,
+that it takes a good deal of thinking to find out the real reasons.
+But they _can_ be found, whether they relate to a fashion, to one of
+the laws of our country, or to the colors on a butterfly's wing.
+
+There is a little piece of verse intended to be comic, which, on the
+contrary, is really serious and philosophical, if you understand it.
+Learn it by heart, and apply it to all kinds and conditions of things,
+and see if it does not help you to explain them to yourself....
+
+  "And Man grew a thumb for that he had need of it,
+  And developed capacities for prey.
+  For the fastest men caught the most animals,
+  And the fastest animals got away from the most men.
+  Whereby all the slow animals were eaten,
+  And all the slow men starved to death."
+
+[Illustration]
+
+
+
+
+
+HOW THE SOIL IS MADE
+
+(FROM THE FORMATION OF VEGETABLE MOULD.)
+
+BY CHARLES DARWIN.
+
+
+[Illustration: W]
+
+Worms have played a more important part in the history of the world
+than most persons would at first suppose. In almost all humid
+countries they are extraordinarily numerous, and for their size
+possess great muscular power. In many parts of England a weight of
+more than ten tons (10,516 kilogrammes) of dry earth annually passes
+through their bodies and is brought to the surface on each acre of
+land; so that the whole superficial bed of vegetable mould passes
+through their bodies in the course of every few years. From the
+collapsing of the old burrows the mould is in constant though slow
+movement, and the particles composing it are thus rubbed together. By
+these means fresh surfaces are continually exposed to the action of
+the carbonic acid in the soil, and of the humus-acids which appear to
+be still more efficient in the decomposition of rocks. The generation
+of the humus-acids is probably hastened during the digestion of the
+many half-decayed leaves which worms consume. Thus the particles of
+earth, forming the superficial mould, are subjected to conditions
+eminently favorable for their decomposition and disintegration.
+Moreover, the particles of the softer rocks suffer some amount of
+mechanical trituration in the muscular gizzards of worms, in which
+small stones serve as mill-stones.
+
+[Illustration: DIAGRAM OF THE ALIMENTARY CANAL OF AN EARTH-WORM.]
+
+The finely levigated castings, when brought to the surface in a moist
+condition, flow during rainy weather down any moderate slope; and the
+smaller particles are washed far down even a gently inclined surface.
+Castings when dry often crumble into small pellets and these are apt
+to roll down any sloping surface. Where the land is quite level and is
+covered with herbage, and where the climate is humid so that much dust
+cannot be blown away, it appears at first sight impossible that there
+should be any appreciable amount of sub-aerial denudation; but worm
+castings are blown, especially while moist and viscid, in one uniform
+direction by the prevalent winds which are accompanied by rain. By
+these several means the superficial mould is prevented from
+accumulating to a great thickness; and a thick bed of mould checks in
+many ways the disintegration of the underlying rocks and fragments of
+rock.
+
+[Illustration: A WORM CASTING, FROM NICE. (Natural Size.)]
+
+The removal of worm-castings by the above means leads to results which
+are far from insignificant. It has been shown that a layer of earth,.2
+of an inch in thickness, is in many places annually brought to the
+surface per acre; and if a small part of this amount flows, or rolls,
+or is washed, even for a short distance, down every inclined surface,
+or is repeatedly blown in one direction, a great effect will be
+produced in the course of ages. It was found by measurements and
+calculations that on a surface with a mean inclination of 9° 26', 2.4
+cubic inches of earth which had been ejected by worms crossed, in the
+course of a year, a horizontal line one yard in length; so that two
+hundred and forty cubic inches would cross a line one hundred yards in
+length. This latter amount in a damp state would weigh eleven and
+one-half pounds. Thus, a considerable weight of earth is continually
+moving down each side of every valley, and will in time reach its bed.
+Finally, this earth will be transported by the streams flowing in the
+valleys into the ocean, the great receptacle for all matter denuded
+from the land. It is known from the amount of sediment annually
+delivered into the sea by the Mississippi, that its enormous
+drainage-area must on an average be lowered.00263 of an inch each
+year; and this would suffice in four and a half million years to lower
+the whole drainage-area to the level of the seashore. So that if a
+small fraction of the layer of fine earth,.2 of an inch in thickness,
+which is annually brought to the surface by worms, is carried away, a
+great result cannot fail to be produced within a period which no
+geologist considers extremely long.
+
+[Illustration: SECTION THROUGH ONE OF THE DRUIDICAL STONES AT
+STONEHENGE, SHOWING HOW MUCH IT HAD SUNK INTO THE GROUND.
+
+(Scale, 1/2 inch to 1 foot.)]
+
+Archaeologists ought to be grateful to worms, as they protect and
+preserve for an indefinitely long period every object, not liable to
+decay, which is dropped on the surface of the land, by burying it
+beneath their castings. Thus, also, many elegant and curious
+tesselated pavements and other ancient remains have been preserved;
+though no doubt the worms have in these cases been largely aided by
+earth washed and blown from the adjoining land, especially when
+cultivated. The old tesselated pavements have, however, often suffered
+by having subsided unequally from being unequally undermined by the
+worms. Even old massive walls may be undermined and subside; and no
+building is in this respect safe, unless the foundations lie six or
+seven feet beneath the surface, at a depth at which worms cannot work.
+It is probable that many monoliths and some old walls have fallen
+down from having been undermined by worms.
+
+Worms prepare the ground in an excellent manner for the growth of
+fibrous-rooted plants and for seedlings of all kinds. They
+periodically expose the mould to the air, and sift it so that no
+stones larger than the particles which they can swallow are left in
+it. They mingle the whole intimately together, like a gardener who
+prepares fine soil for his choicest plants. In this state it is well
+fitted to retain moisture and to absorb all soluble substances, as
+well as for the process of nitrification. The bones of dead animals,
+the harder parts of insects, the shells of land mollusks, leaves,
+twigs, etc., are before long all buried beneath the accumulated
+castings of worms, and are thus brought in a more or less decayed
+state within reach of the roots of plants. Worms likewise drag an
+infinite number of dead leaves and other parts of plants into their
+burrows, partly for the sake of plugging them up and partly as food.
+
+The leaves which are dragged into the burrows as food, after being
+torn into the finest shreds, partially digested and saturated with the
+intestinal and urinary secretions, are commingled with much earth.
+This earth forms the dark-colored, rich humus which almost everywhere
+covers the surface of the land with a fairly well-defined layer or
+mantle. Von Hensen placed two worms in a vessel eighteen inches in
+diameter, which was filled with sand, on which fallen leaves were
+strewed; and these were soon dragged into their burrows to a depth of
+three inches. After about six weeks an almost uniform layer of sand, a
+centimetre (.4 inch) in thickness, was converted into humus by having
+passed through the alimentary canals of these two worms. It is
+believed by some persons that worm-burrows, which often penetrate the
+ground almost perpendicularly to a depth of five or six feet,
+materially aid in its drainage; notwithstanding that the viscid
+castings piled over the mouths of the burrows prevent or check the
+rain-water directly entering them. They allow the air to penetrate
+deeply into the ground. They also greatly facilitate the downward
+passage of roots of moderate size; and these will be nourished by the
+humus with which the burrows are lined. Many seeds owe their
+germination to having been covered by castings; and others buried to a
+considerable depth beneath accumulated castings lie dormant, until at
+some future time they are accidentally uncovered and germinate.
+
+[Illustration: A WORM CASTING FROM SOUTH INDIA. (Natural Size.)]
+
+Worms are poorly provided with sense-organs, for they cannot be said
+to see, although they can just distinguish between light and darkness;
+they are completely deaf, and have only a feeble power of smell; the
+sense of touch alone is well developed. They can, therefore, learn
+little about the outside world, and it is surprising that they should
+exhibit some skill in lining their burrows with their castings and
+with leaves, and in the case of some species in piling up their
+castings into tower-like constructions. But it is far more surprising
+that they should apparently exhibit some degree of intelligence
+instead of a mere blind, instinctive impulse, in their manner of
+plugging up the mouths of their burrows. They act in nearly the same
+manner as would a man, who had to close a cylindrical tube with
+different kinds of leaves, petioles, triangles of paper, etc., for
+they commonly seize such objects by their pointed ends. But with thin
+objects a certain number are drawn in by their broader ends. They do
+not act in the same unvarying manner in all cases, as do most of the
+lower animals; for instance, they do not drag in leaves by their
+foot-stalks, unless the basil part of the blade is as narrow as the
+apex, or narrower than it.
+
+       *       *       *       *       *
+
+When we behold a wide, turf-covered expanse, we should remember that
+its smoothness, on which so much of its beauty depends, is mainly due
+to all the inequalities having been slowly levelled by worms. It is a
+marvellous reflection that the whole of the superficial mould over any
+such expanse has passed, and will again pass, every few years through
+the bodies of worms. The plough is one of the most ancient and most
+valuable of man's inventions; but long before he existed the land was
+in fact regularly ploughed, and, still continues to be thus ploughed
+by earth-worms. It may be doubted whether there are many other animals
+which have played so important a part in the history of the world, as
+have these lowly organized creatures. Some other animals, however,
+still more lowly organized, namely, corals, have done far more
+conspicuous work in having constructed innumerable reefs and islands
+in the great oceans; but these are almost confined to the tropical
+zones.
+
+[Illustration]
+
+
+
+
+ZOÖLOGICAL MYTHS
+
+(FROM FACTS AND FICTIONS OF ZOÖLOGY.)
+
+BY ANDREW WILSON.
+
+
+[Illustration]
+
+When the country swain, loitering along some lane, comes to a
+standstill to contemplate, with awe and wonder, the spectacle of a
+mass of the familiar "hair-eels" or "hair-worms" wriggling about in a
+pool, he plods on his way firmly convinced that, as he has been taught
+to believe, he has just witnessed the results of the transformation of
+some horse's hairs into living creatures. So familiar is this belief
+to people of professedly higher culture than the countryman, that the
+transformation just alluded to has to all, save a few thinking persons
+and zoölogists, become a matter of the most commonplace kind. When
+some quarrymen, engaged in splitting up the rocks, have succeeded in
+dislodging some huge mass of stone, there may sometimes be seen to hop
+from among the débris a lively toad or frog, which comes to be
+regarded by the excavators with feelings akin to those of
+superstitious wonder and amazement. The animal may or may not be
+captured; but the fact is duly chronicled in the local newspapers, and
+people wonder for a season over the phenomenon of a veritable Rip Van
+Winkle of a frog, which to all appearance, has lived for "thousands of
+years in the solid rock." Nor do the hair-worm and the frog stand
+alone in respect of their marvellous origin. Popular zoölogy is full
+of such marvels. We find unicorns, mermaids, and mermen; geese
+developed from the shell-fish known as "barnacles"; we are told that
+crocodiles may weep, and that sirens can sing--in short, there is
+nothing so wonderful to be told of animals that people will not
+believe the tale. Whilst, curiously enough, when they are told of
+veritable facts of animal life, heads begin to shake and doubts to be
+expressed, until the zoölogist despairs of educating people into
+distinguishing fact from fiction, and truth from theories and
+unsupported beliefs. The story told of the old lady, whose youthful
+acquaintance of seafaring habits entertained her with tales of the
+wonders he had seen, finds, after all, a close application in the
+world at large. The dame listened with delight, appreciation, and
+belief, to accounts of mountains of sugar and rivers of rum, and to
+tales of lands where gold and silver and precious stones were more
+than plentiful. But when the narrator descended to tell of fishes that
+were able to raise themselves out of the water in flight, the old
+lady's credulity began to fancy itself imposed upon; for she
+indignantly repressed what she considered the lad's tendency to
+exaggeration, saying, "Sugar mountains may be, and rivers of rum may
+be, but fish that flee ne'er can be!" Many popular beliefs concerning
+animals partake of the character of the old lady's opinions regarding
+the real and fabulous; and the circumstance tells powerfully in favor
+of the opinion that a knowledge of our surroundings in the world, and
+an intelligent conception of animal and plant life, should form part
+of the school-training of every boy and girl, as the most effective
+antidote to superstitions and myths of every kind.
+
+
+[Illustration: FLYING FISH.]
+
+The tracing of myths and fables is a very interesting task, and it
+may, therefore, form a curious study, if we endeavor to investigate
+very briefly a few of the popular and erroneous beliefs regarding
+lower animals. The belief regarding the origin of the hair-worms is
+both widely spread and ancient. Shakespeare tells us that
+
+                                  "Much, is breeding
+  Which, like the courser's hair, hath, yet but life,
+  And not a serpent's poison."
+
+The hair-worms certainly present the appearance of long, delicate
+black hairs, which move about with great activity amidst the mud of
+pools and ditches. These worms, in the early stages of their
+existence, inhabit the bodies of insects, and may be found coiled up
+within the grasshopper, which thus gives shelter to a guest exceeding
+many times the length of the body of its host. Sooner or later the
+hair-worm, or _Gordius aquaticus_ as the naturalist terms it, leaves
+the body of the insect, and lays its eggs, fastened together in long
+strings, in water. From each egg a little creature armed with minute
+hooks is produced, and this young hair-worm burrows its way into the
+body of some insect, there to repeat the history of its parent. Such
+is the well-ascertained history of the hair-worm, excluding entirely
+the popular belief in its origin. There certainly does exist in
+science a theory known as that of "spontaneous generation," which, in
+ancient times, accounted for the production of insects and other
+animals by assuming that they were produced in some mysterious fashion
+out of lifeless matter. But not even the most ardent believer in the
+extreme modification of this theory which holds a place in modern
+scientific belief, would venture to maintain the production of a
+hair-worm by the mysterious vivification of an inert substance such as
+a horse's hair.
+
+The expression "crocodile's tears" has passed into common use, and it
+therefore may be worth while noting the probable origin of this myth.
+Shakespeare, with that wide extent of knowledge which enabled him to
+draw similes from every department of human thought, says that
+
+                          "Gloster's show
+  Beguiles him, as the mournful crocodile
+  With sorrow snares relenting passengers."
+
+The poet thus indicates the belief that not only do crocodiles shed
+tears, but that sympathizing passengers, turning to commiserate the
+reptile's woes, are seized and destroyed by the treacherous creatures.
+That quaint and credulous old author--the earliest writer of English
+prose--Sir John Mandeville, in his "Voiage," or account of his
+"Travile," published about 1356--in which, by the way, there are to be
+found accounts of not a few wonderful things in the way of zoölogical
+curiosities--tells us that in a certain "contre and be all yonde, ben
+great plenty of Crokodilles, that is, a manner of a long Serpent as I
+have seyed before." He further remarks that "these Serpents slew men,"
+and devoured them, weeping; and he tells us, too, that "whan thei
+eaten thei meven (move) the over jowe (upper jaw), and nought the
+nether (lower) jowe: and thei have no tonge (tongue)." Sir John thus
+states two popular beliefs of his time and of days prior to his age,
+namely, that crocodiles move their upper jaws, and that a tongue was
+absent in these animals.
+
+[Illustration: CROCODILE.]
+
+As regards the tears of the crocodile, no foundation of fact exists
+for the belief in such sympathetic exhibitions. But a highly probable
+explanation may be given of the manner in which such a belief
+originated. These reptiles unquestionably emit very loud and
+singularly plaintive cries, compared by some travellers to the
+mournful howling of dogs. The earlier and credulous travellers would
+very naturally associate tears with these cries, and, once begun, the
+supposition would be readily propagated, for error and myth are ever
+plants of quick growth. The belief in the movement of the upper jaw
+rests on apparent basis of fact. The lower jaw is joined to the skull
+very far back on the latter, and the mouth-opening thus comes to be
+singularly wide; whilst, when the mouth opens, the skull and upper jaw
+are apparently observed to move. This is not the case, however; the
+apparent movement arising from the manner in which the lower jaw and
+the skull are joined together. The belief in the absence of the tongue
+is even more readily explained. When the mouth is widely opened, no
+tongue is to be seen. This organ is not only present, but is,
+moreover, of large size; it is, however, firmly attached to the floor
+of the mouth, and is specially adapted, from its peculiar form and
+structure, to assist these animals in the capture and swallowing of
+their prey.
+
+One of the most curious fables regarding animals which can well be
+mentioned, is that respecting the so-called "Bernicle" or "Barnacle
+Geese," which by the naturalists and educated persons of the Middle
+Ages were believed to be produced by those little Crustaceans named
+"Barnacles." With the "Barnacles" every one must be familiar who has
+examined the floating driftwood of the sea-beach, or who has seen
+ships docked in a seaport town. A barnacle is simply a kind of crab
+enclosed in a triangular shell, and attached by a fleshy stalk to
+fixed objects. If the barnacle is not familiar to readers, certain
+near relations of these animals must be well known, by sight at least,
+as amongst the most familiar denizens of our sea-coast. These latter
+are the "Sea-Acorn," or Balani, whose little conical shells we crush
+by hundreds as we walk over the rocks at low-water mark; whilst every
+wooden pile immersed in the sea becomes coated in a short time with a
+thick crust of the "Sea-Acorns." If we place one of these little
+animals, barnacle, or sea-acorn--the latter wanting the stalk of the
+former--in its native waters, we shall observe a beautiful little
+series of feathery plumes to wave backward and forward, and ever and
+anon to be quickly withdrawn into the secure recesses of the shell.
+These organs are the modified feet of the animal, which not only serve
+for sweeping food-particles into the mouth, but act also as
+breathing-organs. We may, therefore, find it a curious study to
+inquire through what extraordinary transformation and confusion of
+ideas such an animal could be credited with giving origin to a
+veritable goose; and the investigation of the subject will also afford
+a singularly apt illustration of the ready manner in which the fable
+of one year or period becomes transmitted and transformed into the
+secure and firm belief of the next.
+
+We may begin our investigation by inquiring into some of the opinions
+which were entertained on this subject and ventilated by certain old
+writers. Between 1154 and 1189 Giraldus Cambrensis, in a work entitled
+"Topographia Hiberniae," written in Latin, remarks concerning "many
+birds which are called Bernacae: against nature, nature produces them
+in a most extraordinary way. They are like marsh geese, but somewhat
+smaller. They are produced from fir timber tossed along the sea, and
+are at first like gum. Afterward they hang down by their beaks, as if
+from a seaweed attached to the timber, surrounded by shells, in order
+to grow more freely," Giraldus is here evidently describing the
+barnacles themselves. He continues: "Having thus, in process of time,
+been clothed with a strong coat of feathers, they either fall into the
+water or fly freely away into the air. They derive their food and
+growth from the sap of the wood or the sea, by a secret and most
+wonderful process of alimentation. I have frequently, with my own
+eyes, seen more than a thousand of these small bodies of birds,
+hanging down on the seashore from one piece of timber, enclosed in
+shells, and already formed." Here, again, our author is speaking of
+the barnacles themselves, with which he naturally confuses the geese,
+since he presumes the Crustaceans are simply geese in an undeveloped
+state. He further informs his readers that, owing to their presumably
+marine origin, "bishops and clergymen in some parts of Ireland do not
+scruple to dine off these birds at the time of fasting, because they
+are not flesh, nor born of flesh," although for certain other and
+theological reasons, not specially requiring to be discussed in the
+present instance, Giraldus disputes the legality of this practice of
+the Hibernian clerics.
+
+In the year 1527 appeared "The Hystory and Croniclis of Scotland, with
+the cosmography and dyscription thairof, compilit be the noble Clerk
+Maister Hector Boece, Channon of Aberdene." Boece's "History" was
+written in Latin; the title we have just quoted being that of the
+English version of the work (1540), which title further sets forth
+that Boece's work was "Translait laitly in our vulgar and commoun
+langage be Maister Johne Bellenden, Archedene of Murray, And
+Imprentit in Edinburgh, be me Thomas Davidson, prenter to the Kyngis
+nobyll grace." In this learned work the author discredits the popular
+ideas regarding the origin of the geese. "Some men belevis that thir
+clakis (geese) growis on treis be the nebbis (bills). Bot thair
+opinoun is vane. And becaus the nature and procreatioun of thir clakis
+is strange, we have maid na lytyll laboure and deligence to serche ye
+treuth and verite yairof, we have salit (sailed) throw ye seis quhare
+thir clakis ar bred, and I fynd be gret experience, that the nature of
+the seis is mair relevant caus of thair procreatioun than ony uthir
+thyng." According to Boece, then, "the nature of the seis" formed the
+chief element in the production of the geese, and our author proceeds
+to relate how "all treis (trees) that ar casein in the seis be proces
+of tyme apperis first wormeetin (worm-eaten), and in the small boris
+and hollis (holes) thairof growis small worms." Our author no doubt
+here alludes to the ravages of the Teredo, or ship-worm, which burrows
+into timber, and with which the barnacles themselves are thus
+confused. Then he continues, the "wormis" first "schaw (show) thair
+heid and feit, and last of all thay schaw thair plumis and wyngis.
+Finaly, quhen thay ar cumyn to the just mesure and quantite of geis,
+thay fle in the aire as othir fowlis dois, as was notably provyn, in
+the yeir of God ane thousand iii hundred lxxxx, in sicht of mony
+pepyll, besyde the castell of Petslego." On the occasion referred to,
+Boece tells us that a great tree was cast on shore, and was divided,
+by order of the "laird" of the ground, by means of a saw. Wonderful to
+relate, the tree was found not merely to be riddled with a "multitude
+of wormis," throwing themselves out of the holes of the tree, but some
+of the "wormis" had "baith heid, feit, and wyngis," but, adds the
+author, "they had no fedderis (feathers)."
+
+Unquestionably, either "the scientific use of the imagination" had
+operated in this instance in inducing the observers to believe that in
+this tree, riddled by the ship-worms and possibly having barnacles
+attached to it, they beheld young geese; or Boece had construed the
+appearances described as those representing the embryo stages of the
+barnacle geese.
+
+Boece further relates how a ship named the Christofir was brought to
+Leith, and was broken down because her timbers had grown old and
+failing. In these timbers were beheld the same "wormeetin"
+appearances, "all the hollis thairof" being "full of geis." Boece
+again most emphatically rejects the idea that the "geis" were produced
+from the wood of which the timbers were composed, and once more
+proclaims his belief that the "nature of the seis resolvit in geis"
+may be accepted as the true and final explanation of their origin. A
+certain "Maister Alexander Galloway" had apparently strolled with the
+historian along the sea-coast, the former giving "his mynd with maist
+ernist besynes to serche the verite of this obscure and mysty dowtis."
+Lifting up a piece of tangle, they beheld the seaweed to be hanging
+full of mussel-shells from the root to the branches. Maister Galloway
+opened one of the mussel-shells, and was "mair astonis than afore" to
+find no fish therein, but a perfectly shaped "foule, smal and gret,"
+as corresponded to the "quantity of the shell." And once again Boece
+draws the inference that the trees or wood on which the creatures are
+found have nothing to do with the origin of the birds; and that the
+fowls are begotten of the "occeane see, quhilk," concludes our author,
+"is the caus and production of mony wonderful thingis."
+
+More than fifty years after the publication of Boece's "History," old
+Gerard of London, the famous "master in chirurgerie" of his day, gave
+an account of the barnacle goose, and not only entered into minute
+particulars of its growth and origin, but illustrated its manner of
+production by means of the engraver's art of his day. Gerard's
+"Herball," published in 1597, thus contains, amongst much that is
+curious in medical lore, a very quaint piece of zoölogical history. He
+tells us that "in the north parts of Scotland, and the Hands adjacent,
+called Orchades (Orkneys)," are found "certaine trees, whereon doe
+growe certaine shell fishes, of a white colour tending to russet;
+wherein are conteined little living creatures: which shels in time of
+maturitie doe open, and out of them grow those little living foules
+whom we call Barnakles, in the north of England Brant Geese, and in
+Lancashire tree Geese; but the other that do fall upon the land,
+perish, and come to nothing: thus much by the writings of others, and
+also from the mouths of people of those parts, which may," concludes
+Gerard, "very well accord with truth."
+
+Not content with hearsay evidence, however, Gerard relates what his
+eyes saw and hands touched. He describes how on the coasts of a
+certain "small Hand in Lancashire called Pile of Foulders" (probably
+Peel Island), the wreckage of ships is cast up by the waves, along
+with the trunks and branches "of old and rotten trees." On these
+wooden rejectamenta "a certaine spume or froth" grows, according to
+Gerard. This spume "in time breedeth unto certaine shels, in shape
+like those of the muskle, but sharper pointed, and of a whitish
+color." This description, it may be remarked, clearly applies to the
+barnacles themselves. Gerard then continues to point out how, when the
+shell is perfectly formed, it "gapeth open, and the first thing that
+appeereth is the foresaid lace or string"--the substance described by
+Gerard as contained within the shell--"next come the legs of the Birde
+hanging out; and as it groweth greater, it openeth the shell by
+degrees, till at length it is all come forth, and hangeth only by the
+bill; in short space after it commeth to full maturitie, and falleth
+into the sea, where it gathereth feathers, and groweth to a foule,
+bigger than a Mallard, and lesser than a Goose, having blacke legs and
+bill or beake, and feathers blacke and white ... which the people of
+Lancashire call by no other name than a tree Goose."
+
+[Illustration: FIG. 1. THE BARNACLE TREE. (From Gerard's "Herball.")]
+
+Accompanying this description is the engraving of the barnicle tree
+(Fig. 1) bearing its geese progeny. From the open shells in two cases,
+the little geese are seen protruding, whilst several of the
+fully-fledged fowls are disporting themselves in the sea below.
+Gerard's concluding piece of information, with its exordium, must not
+be omitted. "They spawne," says the wise apothecary, "as it were, in
+March or Aprill; the Geese are found in Maie or June, and come to
+fulnesse of feathers in the moneth after. And thus hauing, through
+God's assistance, discoursed somewhat at large of Grasses, Herbes,
+Shrubs, Trees, Mosses, and certaine excrescences of the earth, with
+other things moe incident to the Historic thereof, we conclude and end
+our present volume, with this woonder of England. For which God's name
+be euer honored and praised." It is to be remarked that Gerard's
+description of the goose-progeny of the barnacle tree exactly
+corresponds with the appearance of the bird known to ornithologists as
+the "barnacle-goose"; and there can be no doubt that, skilled as was
+this author in the natural history lore of his day, there was no other
+feeling in his mind than that of firm belief in and pious wonder at
+the curious relations between the shells and their fowl-offspring.
+Gerard thus attributes the origin of the latter to the barnacles. He
+says nothing of the "wormeetin" holes and burrows so frequently
+mentioned by Boece, nor would he have agreed with the latter in
+crediting the "nature of the occeane see" with their production, save
+in so far as their barnacle-parents lived and existed in the waters of
+the ocean.
+
+The last account of this curious fable which we may allude to in the
+present instance is that of Sir Robert Moray, who, in his work
+entitled "A Relation concerning Barnacles," published in the
+_Philosophical Transactions_ of the Royal Society in 1677-78, gives a
+succinct account of these crustaceans and their bird-progeny. Sir
+Robert is described as "lately one of his Majesties Council for the
+Kingdom of Scotland," and we may therefore justly assume his account
+to represent that of a cultured, observant person of his day and
+generation. The account begins by remarking that the "most ordinary
+trees" found in the western islands of Scotland "are Firr and Ash."
+"Being," continues Sir Robert, "in the Island of East (Uist), I saw
+lying upon the shore a cut of a large Firr tree of about 2-1/2 foot
+diameter, and 9 or 10 foot long; which had lain so long out of the
+water that it was very dry: And most of the shells that had formerly
+cover'd it, were worn or rubb'd off. Only on the parts that lay next
+the ground, there still hung multitudes of little Shells; having
+within them little Birds, perfectly shap'd, supposed to be Barnacles."
+Here again the description applies to the barnacles; the "little
+birds" they are described as containing being of course the bodies of
+the shell-fish.
+
+"The Shells," continues the narrator, "hang at the Tree by a Neck
+longer than the Shell;" this "neck" being represented by the stalk of
+the barnacle. The neck is described as being composed "of a kind of
+filmy substance, round, and hollow, and creased, not unlike the
+Wind-pipe of a Chicken; spreading out broadest where it is fastened to
+the Tree, from which it seems to draw and convey the matter which
+serves for the growth and vegetation of the Shell and the little Bird
+within it." Sir Robert Moray therefore agrees in respect of the manner
+of nourishment of the barnacles with the opinion of Giraldus already
+quoted. The author goes on to describe the "Bird" found in every
+shell he opened; remarking that "there appeared nothing wanting as to
+the internal parts, for making up a perfect Sea-fowl: every little
+part appearing so distinctly, that the whole looked like a large Bird
+seen through a concave or diminishing Glass, colour and feature being
+everywhere so clear and neat." The "Bird" is most minutely described
+as to its bill, eyes, head, neck, breast, wings, tail, and feet, the
+feathers being "everywhere perfectly shaped, and blackish-coloured.
+All being dead and dry," says Sir Robert, "I did not look after the
+Internal parts of them," a statement decidedly inconsistent with his
+previous assertion as to the perfect condition of the "internal
+parts"; and he takes care to add, "nor did I ever see any of the
+little Birds alive, nor met with anybody that did. Only some credible
+persons," he concludes, "have assured me they have seen some as big as
+their fist."
+
+[Illustration: FIG. 2. BARNACLE TREE. (From Munster's "Cosmography.")]
+
+This last writer thus avers that he saw little birds within the shells
+he clearly enough describes as those of the barnacles. We must either
+credit Sir Robert with describing what he never saw, or with
+misconstruing what he did see. His description of the goose
+corresponds with that of the barnacle goose, the reputed progeny of
+the shells; and it would, therefore, seem that this author, with the
+myth at hand, saw the barnacles only with the eyes of a credulous
+observer, and thus beheld, in the inside of each shell--if, indeed,
+his research actually extended thus far--the reproduction in miniature
+of a goose, with which, as a mature bird, he was well acquainted.
+
+On p. 157 is a woodcut, copied from Munster's "Cosmography" (1550), a
+very popular book in its time, showing the tree with its fruit, and
+the geese which are supposed to have just escaped from it.
+
+This historical ramble may fitly preface what we have to say regarding
+the probable origin of the myth. By what means could the barnacles
+become credited with the power of producing the well-known geese? Once
+started, the progress and growth of the myth are easily accounted for.
+The mere transmission of a fable from one generation or century to
+another is a simply explained circumstance, and one exemplified by the
+practices of our own times. The process of accretion and addition is
+also well illustrated in the perpetuation of fables; since the tale is
+certain to lose nothing in its historical journey, but, on the
+contrary, to receive additional elaboration with increasing age.
+Professor Max Müller, after discussing various theories of the origin
+of the barnacle myth, declares in favor of the idea that confusion of
+language and alteration of names lie at the root of the error. The
+learned author of the "Science of Language" argues that the true
+barnacles were named, properly enough, Bernaculae, and lays stress on
+the fact that Bernicle geese were first caught in Ireland. That
+country becomes _Hibernia_ in Latin, and the Irish geese were
+accordingly named Hibernicae, or Hiberniculae. By the omission of the
+first syllable--no uncommon operation for words to undergo--we obtain
+the name Berniculae for the geese, this term being almost synonymous
+with the name Bernaculae already applied, as we have seen, to the
+barnacles. Bernicle geese and bernicle shells, confused in name, thus
+became confused in nature; and, once started, the ordinary process of
+growth was sufficient to further intensify, and render more realistic,
+the story of the bernicle tree and its wonderful progeny.
+
+By way of a companion legend to that of the barnacle tree, we may
+select the story of the "Lamb Tree" of Cathay, told by Sir John
+Mandeville, whose notes of travel regarding crocodiles' tears, and
+other points in the conformation of these reptiles, have already been
+referred to. Sir John, in that chapter of his work which treats "Of
+the Contries and Yles that ben bezonde the Lond of Cathay; and of the
+Frutes there," etc., relates that in Cathay "there growethe a manner
+of Fruyt, as thoughe it were Gowrdes: and whan thei ben rype, men
+kutten (cut) hem a to (them in two), and men fyndem with inne a
+lytylle Best (beast), in Flessche in Bon and Blode (bone and blood) as
+though it were a lytylle Lomb (lamb) with outen wolle (without wool).
+And men eaten both the Frut and the Best; and that," says Sir John,
+"is a great marveylle. Of that frut," he continues, "I have eten; alle
+thoughe it were wondirfulle"--this being added, no doubt, from an
+idea that there might possibly be some stay-at-home persons who would
+take Sir John's statement _cum grano salis_. "But," adds this worthy
+"knyght of Ingolond," "I knowe wel that God is marveyllous in His
+Werkes." Not to be behind the inhabitants of Cathay in a tale of
+wonders, the knight related to these Easterns "als gret a marveylle to
+hem that is amonges us; and that was of the Bernakes. For I tolde him
+hat in oure Countree weren Trees that beren a Fruyt, that becomen
+Briddes (birds) fleeynge: and tho that fellen in the Water lyven
+(live); and thei that fallen on the Erthe dyen anon: and thei ben
+right gode to mannes mete (man's meat). And here had thei als gret
+marvayle," concludes Sir John, "that sume of hem trowed it were an
+impossible thing to be." Probably the inhabitants of Cathay, knowing
+their own weakness as regards the lamb tree, might possess a
+fellow-feeling for their visitor's credulity, knowing well, from
+experience, the readiness with which a "gret marvayle" could be
+evolved and sustained.
+
+Passing from the sphere of the mythical and marvellous as represented
+in mediaeval times, we may shortly discuss a question, which, of all
+others, may justly claim a place in the records of Zoölogical
+curiosities--namely, the famous and oft-repeated story of the "Toad
+from the solid rock," as the country newspapers style the incident.
+Regularly, year by year, and in company with the reports of the
+sea-serpent's reappearance, we may read of the discoveries of toads
+and frogs in situations and under circumstances suggestive of a
+singular vitality on the part of the amphibians, of more than usual
+credulity on the part of the hearers, or of a large share of
+inventive genius in the narrators of such tales. The question
+possesses for every one a certain degree of interest, evoked by the
+curious and strange features presented on the face of the tales. And
+it may therefore not only prove an interesting but also a useful
+study, if we endeavor to arrive at some just and logical conceptions
+of these wonderful narrations.
+
+[Illustration]
+
+Instances of the discovery of toads and frogs in solid rocks need not
+be specially given; suffice it to say, that these narratives are
+repeated year by year with little variation. A large block of stone or
+face of rock is detached from its site, and a toad or frog is seen
+hereafter to be hopping about in its usual lively manner. The
+conclusion to which the bystanders invariably come is that the animal
+must have been contained within the rock, and that it was liberated by
+the dislodgement of the mass. Now, in many instances, cases of the
+appearance of toads during quarrying operations have been found, on
+close examination, to present no evidence whatever that the appearance
+of the animals was due to the dislodgement of the stones. A frog or
+toad may be found hopping about among some recently formed débris, and
+the animal is at once seized upon and reported as having emerged from
+the rocks into the light of day. There is in such a case not the
+slightest ground for supposing any such thing; and the animal may more
+reasonably be presumed to have simply hopped into the débris from its
+ordinary habitat. But laying aside narratives of this kind, which lose
+their plausibility under a very commonplace scrutiny, there still
+exist cases, reported in an apparently exact and truthful manner, in
+which these animals have been alleged to appear from the inner
+crevices of rocks after the removal of large masses of the formations.
+We shall assume these latter tales to contain a plain, unvarnished
+statement of what was observed, and deal with the evidence they
+present on this footing.
+
+[Illustration: A TOAD.]
+
+One or two notable examples of such verified tales are related by
+Smellie, in his "Philosophy of Natural History." Thus, in the "Memoirs
+of the French Academy of Sciences" for 1719, a toad is described as
+having been found in the heart of an elm tree; and another is stated
+to have been found in the heart of an old oak tree, in 1731, near
+Nantz. The condition of the trees is not expressly stated, nor are we
+afforded any information regarding the appearance of the
+toads--particulars of considerable importance in view of the
+suggestions and explanations to be presently brought forward. Smellie
+himself, while inclined to be sceptical in regard to the truth or
+exactness of many of the tales told of the vitality of toads, regards
+the matter as affording food for reflection, since he remarks, "But I
+mean not to persuade, for I cannot satisfy myself; all I intend is, to
+recommend to those gentlemen who may hereafter chance to see such rare
+phenomena, a strict examination of every circumstance that can throw
+light upon a subject so dark and mysterious; for the vulgar, ever
+inclined to render uncommon appearances still more marvellous, are not
+to be trusted."
+
+This author strikes the key-note of the inquiry in his concluding
+words, and we shall find that the explanation of the matter really
+lies in the clear understanding of what are the probabilities, and
+what the actual details, of the cases presented for consideration. We
+may firstly, then, glance at a few of the peculiarities of the frogs
+and toads, regarded from a zoölogical point of view. As every one
+knows, these animals emerge from the egg in the form of little
+fish-like "tadpoles," provided with outside gills, which are soon
+replaced by inside gills, resembling those of fishes. The hind legs
+are next developed, and the fore limbs follow a little later; whilst,
+with the development of lungs, and the disappearance of the gills and
+tail, the animal leaves the water, and remains for the rest of its
+life an air-breathing, terrestrial animal. Then, secondly, in the
+adult frog or toad, the naturalist would point to the importance of
+the skin as not only supplementing, but, in some cases, actually
+supplanting the work of the lungs as the breathing organ. Frogs and
+toads will live for months under water, and will survive the excision
+of the lungs for like periods; the skin in such cases serving as the
+breathing surface. A third point worthy of remembrance is included in
+the facts just related, and is implied in the information that these
+animals can exist for long periods without food, and with but a
+limited supply of air. We can understand this toleration on the part
+of these animals when we take into consideration their cold-blooded
+habits, which do not necessitate, and which are not accompanied by,
+the amount of vital activity we are accustomed to note in higher
+animals. And, as a last feature in the purely scientific history of
+the frogs and toads, it may be remarked that these animals are known
+to live for long periods. One pet toad is mentioned by a Mr. Arscott
+as having attained, to his knowledge, the age of thirty-six years; and
+a greater age still might have been recorded of this specimen, but for
+the untoward treatment it sustained at the hands, or rather beak, of a
+tame raven. In all probability it may be safely assumed that, when the
+conditions of life are favorable, these creatures may attain a highly
+venerable age--regarding the lapse of time from a purely human and
+interested point of view.
+
+We may now inquire whether or not the foregoing considerations may
+serve to throw any light upon the tales of the quarryman. The first
+point to which attention may be directed is that involved in the
+statement that the amphibian has been imprisoned in a _solid_ rock.
+Much stress is usually laid on the fact that the rock was solid; this
+fact being held to imply the great age, not to say antiquity, of the
+rock and its supposed tenant. The impartial observer, after an
+examination of the evidence presented, will be inclined to doubt
+greatly the justification for inserting the adjective "solid"; for
+usually no evidence whatever is forthcoming as to the state of the
+rock prior to its removal. No previous examination of the rock is or
+can be made, from the circumstance that no interest can possibly
+attach to its condition until its removal reveals the apparent wonder
+it contained, in the shape of the live toad. And it is equally
+important to note that we rarely, if ever, find mention of any
+examination of the rock being made subsequently to the discovery.
+Hence, a first and grave objection may be taken to the validity of the
+supposition that the rock was solid, and it may be fairly urged that
+on this supposition the whole question turns and depends. For if the
+rock cannot be proved to have been impermeable to and barred against
+the entrance of living creatures, the objector may proceed to show the
+possibility of the toad having gained admission, under certain notable
+circumstances, to its prison-house.
+
+The frog or toad in its young state, and having just entered upon its
+terrestrial life, is a small creature, which could, with the utmost
+ease, wriggle into crevices and crannies of a size which would almost
+preclude such apertures being noticed at all. Gaining access to a
+roomier crevice or nook within, and finding there a due supply of air,
+along with a dietary consisting chiefly of insects, the animal would
+grow with tolerable rapidity, and would increase to such an extent
+that egress through its aperture of entrance would become an
+impossibility. Next, let us suppose that the toleration of the toad's
+system to starvation and to a limited supply of air is taken into
+account, together with the fact that these creatures will hibernate
+during each winter, and thus economize, as it were, their vital
+activity and strength; and after the animal has thus existed for a
+year or two--no doubt under singularly hard conditions--let us imagine
+that the rock is split up by the wedge and lever of the excavator. We
+can then readily enough account for the apparently inexplicable story
+of "the toad in the rock." "There is the toad and here is the solid
+rock," say the gossips. "There is an animal which has singular powers
+of sustaining life under untoward conditions, and which, in its young
+state, could have gained admittance to the rock through a mere
+crevice," says the naturalist in reply. Doubtless, the great army of
+the unconvinced may still believe in the tale as told them; for the
+weighing of evidence and the placing _pros_ and _cons_ in fair
+contrast are not tasks of congenial or wonted kind in the ordinary run
+of life. Some people there will be who will believe in the original
+solid rock and its toad, despite the assertion of the geologists that
+the earliest fossils of toads appear in almost the last-formed rocks,
+and that a live toad in rocks of very ancient age--presuming,
+according to the popular belief, that the animal was enclosed when the
+rock was formed--would be as great an anomaly and wonder as the
+mention, as an historical fact, of an express train or the telegraph
+in the days of the patriarchs. In other words, the live toad which
+hops out of an Old Red Sandstone rock must be presumed, on the popular
+belief, to be older by untold ages than the oldest fossil frogs and
+toads. The reasonable mind, however, will ponder and consider each
+feature of the case, and will rather prefer to countenance a
+supposition based on ordinary experience, than an explanation brought
+ready-made from the domain of the miraculous; whilst not the least
+noteworthy feature of these cases is that included in the remark of
+Smellie, respecting the tendency of uneducated and superstitious
+persons to magnify what is uncommon, and in his sage conclusion that
+as a rule such persons in the matter of their relations "are not to be
+trusted."
+
+But it must also be noted that we possess valuable evidence of a
+positive and direct kind bearing on the duration of life in toads
+under adverse circumstances. As this evidence tells most powerfully
+against the supposition that the existence of those creatures can be
+indefinitely prolonged, it forms of itself a veritable court of appeal
+in the cases under discussion. The late Dr. Buckland, curious to learn
+the exact extent of the vitality of the toad, caused, in the year
+1825, two large blocks of stone to be prepared. One of the blocks was
+taken from the oölite limestone, and in this first stone twelve cells
+were excavated. Each cell was one foot deep and five inches in
+diameter. The mouth of each cell was grooved so as to admit of two
+covers being placed over the aperture; the first or lower cover being
+of glass, and the upper one of slate. Both covers were so adapted that
+they could be firmly luted down with clay or putty; the object of this
+double protection being that the slate cover could be raised so as to
+inspect the contained object through the closed glass cover without
+admitting air. In the second or sandstone block, a series of twelve
+cells was also excavated; these latter cells being, however, of
+smaller size than those of the limestone block, each cell being only
+six inches in depth by five inches in diameter. These cells were
+likewise fitted with double covers.
+
+On November 26th, 1825, a live toad--kept for some time previously to
+insure its being healthy--was placed in each of the twenty-four cells.
+The largest specimen weighed 1185 grains, and the smallest 115 grains.
+The stones and the immured toads were buried on the day mentioned,
+three feet deep, in Dr. Buckland's garden. There they lay until
+December 10th, 1826, when they were disinterred and their tenants
+examined. All the toads in the smaller cells of the sandstone block
+were dead, and from the progress of decomposition it was inferred that
+they had succumbed long before the date of disinterment. The majority
+of the toads in the limestone block were alive, and, curiously enough,
+one or two had actually increased in weight. Thus, No. 5, which at the
+commencement of its captivity had weighed 1185 grains, had increased
+to 1265 grains; but the glass cover of No. 5's cell was found to be
+cracked. Insects and air must therefore have obtained admittance and
+have afforded nourishment to the imprisoned toad; this supposition
+being rendered the more likely by the discovery that in one of the
+cells, the covers of which were also cracked and the tenant of which
+was dead, numerous insects were found. No. 9, weighing originally 988
+grains, had increased during its incarceration to 1116 grains; but
+No. 1, which in the year 1825 had weighed 924 grains, was found in
+December, 1826, to have decreased to 698 grains; and No. 11,
+originally weighing 936 grains, had likewise disagreed with the
+imprisonment, weighing only 652 grains when examined in 1826.
+
+At the period when the blocks of stone were thus prepared, four toads
+were pinned up in holes five inches deep and three inches in diameter,
+cut in the, stem of an apple-tree; the holes being firmly plugged with
+tightly fitting wooden plugs. These four toads were found to be dead
+when examined along with the others in 1826; and of four others
+enclosed in basins made of plaster of Paris, and which were also
+buried in Dr. Buckland's garden, two were found to be dead at the end
+of a year, their comrades being alive, but looking starved and meagre.
+The toads which were found alive in the limestone block in December,
+1826, were again immured and buried, but were found to be dead,
+without leaving a single survivor, at the end of the second year of
+their imprisonment.
+
+These experiments may fairly be said to prove two points. They firstly
+show that under circumstances even of a favorable kind when compared
+with the condition popularly believed in--namely, that of being
+enclosed in a _solid_ rock--the limit of the toad's life may be
+assumed to be within two years; this period being no doubt capable of
+being extended when the animal gains a slight advantage, exemplified
+by the admission of air and insect-food. Secondly, we may reasonably
+argue that these experiments show that toads when rigorously treated,
+like other animals, become starved and meagre, and by no means
+resemble the lively, well-fed animals reported as having emerged from
+an imprisonment extending, in popular estimation, through periods of
+inconceivable duration.
+
+These tales are, in short, as devoid of actual foundation as are the
+modern beliefs in the venomous properties of the toad, or the ancient
+beliefs in the occult and mystic powers of various parts of its frame
+when used in incantations. Shakespeare, whilst attributing to the toad
+venomous qualities, has yet immortalized it in his famous simile by
+crediting it with the possession of a "precious jewel." But even in
+the latter case the animal gets but scant justice; for science strips
+it of its poetical reputation, and in this, as in other respects,
+shows it, despite fable and myth, to be zoölogically an interesting,
+but otherwise a commonplace member of the animal series.
+
+[Illustration]
+
+
+
+
+ON A PIECE OF CHALK
+
+_A LECTURE TO WORKING MEN_.
+
+(Delivered in England.)
+
+BY T.H. HUXLEY.
+
+
+[Illustration: A CHALK CLIFF.]
+
+If a well were to be sunk at our feet in the midst of the city of
+Norwich, the diggers would very soon find themselves at work in that
+white substance almost too soft to be called rock, with which we are
+all familiar as "chalk."
+
+Not only here, but over the whole county of Norfolk, the well-sinker
+might carry his shaft down many hundred feet without coming to the end
+of the chalk; and, on the sea-coast, where the waves have pared away
+the face of the land which breasts them, the scarped faces of the high
+cliffs are often wholly formed of the same material. Northward, the
+chalk may be followed as far as Yorkshire; on the south coast it
+appears abruptly in the picturesque western bays of Dorset, and breaks
+into the Needles of the Isle of Wight; while on the shores of Kent it
+supplies that long line of white cliffs to which England owes her name
+of Albion.
+
+Were the thin soil which covers it all washed away, a curved band of
+white chalk, here broader, and there narrower, might be followed
+diagonally across England from Lulworth in Dorset, to Flamborough Head
+in Yorkshire--a distance of over two hundred and eighty miles as the
+crow flies.
+
+From this band to the North Sea, on the east, and the Channel, on the
+south, the chalk is largely hidden by other deposits; but, except in
+the Weald of Kent and Sussex, it enters into the very foundation of
+all the south-eastern counties.
+
+Attaining, as it does in some places, a thickness of more than a
+thousand feet, the English chalk must be admitted to be a mass of
+considerable magnitude. Nevertheless, it covers but an insignificant
+portion of the whole area occupied by the chalk formation of the
+globe, which has precisely the same general character as ours, and is
+found in detached patches, some less, and others more extensive, than
+the English.
+
+Chalk occurs in north-west Ireland; it stretches over a large part of
+France--the chalk which underlies Paris being, in fact, a continuation
+of that of the London basin; it runs through Denmark and Central
+Europe, and extends southward to North Africa; while eastward, it
+appears in the Crimea and in Syria, and may be traced as far as the
+shores of the Sea of Aral, in Central Asia.
+
+If all the points at which true chalk occurs were circumscribed, they
+would lie within an irregular oval about three thousand miles in long
+diameter--the area of which would be as great as that of Europe, and
+would many times exceed that of the largest existing inland sea--the
+Mediterranean.
+
+Thus the chalk is no unimportant element in the masonry of the earth's
+crust, and it impresses a peculiar stamp, varying with the conditions
+to which it is exposed, on the scenery of the districts in which it
+occurs. The undulating downs and rounded coombs, covered with
+sweet-grassed turf, of our inland chalk country, have a peacefully
+domestic and mutton-suggesting prettiness, but can hardly be called
+either grand or beautiful. But on our southern coasts, the wall-sided
+cliffs, many hundred feet high, with vast needles and pinnacles
+standing out in the sea, sharp and solitary enough to serve as perches
+for the wary cormorant, confer a wonderful beauty and grandeur upon
+the chalk headlands. And in the East, chalk has its share in the
+formation of some of the most venerable of mountain ranges, such as
+the Lebanon.
+
+       *       *       *       *       *
+
+What is this wide-spread component of the surface of the earth? and
+whence did it come?
+
+You may think this no very hopeful inquiry. You may not unnaturally
+suppose that the attempt to solve such problems as these can lead to
+no result, save that of entangling the inquirer in vague speculations,
+incapable of refutation and of verification.
+
+If such were really the case, I should have selected some other
+subject than a "piece of chalk" for my discourse. But, in truth,
+after much deliberation, I have been unable to think of any topic
+which would so well enable me to lead you to see how solid is the
+foundation upon which some of the most startling conclusions of
+physical science rest.
+
+A great chapter of the history of the world is written in the chalk.
+Few passages in the history of man can be supported by such an
+overwhelming mass of direct and indirect evidence as that which
+testifies to the truth of the fragment of the history of the globe,
+which I hope to enable you to read, with your own eyes, to-night.
+
+[Illustration: MICROSCOPIC SECTION OF CHALK.
+
+(Magnified nearly 300 times.)
+
+1. Textularia. 2. Globigerina. 3. Rotalia. 4. Coccoliths.]
+
+Let me add, that few chapters of human history have a more profound
+significance for ourselves. I weigh my words well when I assert, that
+the man who should know the true history of the bit of chalk which
+every carpenter carries about in his breeches' pocket, though ignorant
+of all other history, is likely, if he will think his knowledge out to
+its ultimate results, to have a truer, and therefore a better,
+conception of this wonderful universe, and of man's relation to it,
+than the most learned student who is deep-read in the records of
+humanity and ignorant of those of nature.
+
+The language of the chalk is not hard to learn, not nearly so hard as
+Latin, if you only want to get at the broad features of the story it
+has to tell; and I propose that we now set to work to spell that story
+out together.
+
+We all know that if we "burn" chalk, the result is quicklime. Chalk,
+in fact, is a compound of carbonic acid gas and lime; and when you
+make it very hot, the carbonic acid flies away and the lime is left.
+
+By this method of procedure we see the lime, but we do not see the
+carbonic acid. If, on the other hand, you were to powder a little
+chalk and drop it into a good deal of strong vinegar, there would be a
+great bubbling and fizzing, and, finally, a clear liquid, in which no
+sign of chalk would appear. Here you see the carbonic acid in the
+bubbles; the lime, dissolved in the vinegar, vanishes from sight.
+There are a great many other ways of showing that chalk is essentially
+nothing but carbonic acid and quicklime. Chemists enunciate the result
+of all the experiments which prove this, by stating that chalk is
+almost wholly composed of "carbonate of lime."
+
+It is desirable for us to start from the knowledge of this fact,
+though it may not seem to help us very far toward what we seek. For
+carbonate of lime is a widely-spread substance, and is met with under
+very various conditions. All sorts of limestones are composed of more
+or less pure carbonate of lime. The crust which is often deposited by
+waters which have drained through limestone rocks, in the form of what
+are called stalagmites and stalactites, is carbonate of lime. Or, to
+take a more familiar example, the fur on the inside of a tea-kettle is
+carbonate of lime; and, for anything chemistry tells us to the
+contrary, the chalk might be a kind of gigantic fur upon the bottom of
+the earth-kettle, which is kept pretty hot below.
+
+Let us try another method of making the chalk tell us its own history.
+To the unassisted eye chalk looks simply like a very loose and open
+kind of stone. But it is possible to grind a slice of chalk down so
+thin that you can see through it--until it is thin enough, in fact, to
+be examined with any magnifying power that may be thought desirable. A
+thin slice of the fur of a kettle might be made in the same way. If it
+were examined microscopically, it would show itself to be a more or
+less distinctly laminated mineral substance, and nothing more.
+
+But the slice of chalk presents a totally different appearance when
+placed under the microscope. The general mass of it is made up of very
+minute granules; but, imbedded in this matrix, are innumerable bodies,
+some smaller and some larger, but, on a rough average, not more than a
+hundredth of an inch in diameter, having a well-defined shape and
+structure. A cubic inch of some specimens of chalk may contain
+hundreds of thousands of these bodies, compacted together with
+incalculable millions of the granules.
+
+[Illustration: CHALK.
+
+(Magnified nearly 100 diameters.)]
+
+The examination of a transparent slice gives a good notion of the
+manner in which the components of the chalk are arranged, and of
+their relative proportions. But, by rubbing up some chalk with a brush
+in water and then pouring off the milky fluid, so as to obtain
+sediments of different degrees of fineness, the granules and the
+minute rounded bodies may be pretty well separated from one another,
+and submitted to microscopic examination, either as opaque or as
+transparent objects. By combining the views obtained in these various
+methods, each of the rounded bodies may be proved to be a
+beautifully-constructed calcareous fabric, made up of a number of
+chambers, communicating freely with one another. The chambered bodies
+are of various forms. One of the commonest is something like a
+badly-grown raspberry, being formed of a number of nearly globular
+chambers of different sizes congregated together. It is called
+Globigerina, and some specimens of chalk consist of little else than
+Globigerinæ and granules.
+
+[Illustration: GLOBIGERINA.]
+
+Let us fix our attention upon the Globigerina. It is the spoor of the
+game we are tracking. If we can learn what it is and what are the
+conditions of its existence, we shall see our way to the origin and
+past history of the chalk.
+
+A suggestion which may naturally enough present itself is, that these
+curious bodies are the result of some process of aggregation which has
+taken place in the carbonate of lime; that, just as in winter, the
+rime on our windows simulates the most delicate and elegantly
+arborescent foliage--proving that the mere mineral matter may, under
+certain conditions, assume the outward form of organic bodies--so this
+mineral substance, carbonate of lime, hidden away in the bowels of
+the earth, has taken the shape of these chambered bodies. I am not
+raising a merely fanciful and unreal objection. Very learned men, in
+former days, have even entertained the notion that all the formed
+things found in rocks are of this nature; and if no such conception is
+at present held to be admissible, it is because long and varied
+experience has now shown that mineral matter never does assume the
+form and structure we find in fossils. If anyone were to try to
+persuade you that an oyster-shell (which is also chiefly composed of
+carbonate of lime) had crystallized out of sea-water, I suppose you
+would laugh at the absurdity. Your laughter would be justified by the
+fact that all experience tends to show that oyster-shells are formed
+by the agency of oysters, and in no other way. And if there were no
+better reasons, we should be justified, on like grounds, in believing
+that Globigerina is not the product of anything but vital activity.
+
+Happily, however, better evidence in proof of the organic nature of
+the Globigerinæ than that of analogy is forthcoming. It so happens
+that calcareous skeletons, exactly similar to the Globigerinæ of the
+chalk, are being formed, at the present moment, by minute living
+creatures, which flourish in multitudes, literally more numerous than
+the sands of the sea-shore, over a large extent of that part of the
+earth's surface which is covered by the ocean.
+
+The history of the discovery of these living Globigerinæ, and of the
+part which they play in rock-building, is singular enough. It is a
+discovery which, like others of no less scientific importance, has
+arisen, incidentally, out of work devoted to very different and
+exceedingly practical interests.
+
+When men first took to the sea, they speedily learned to look out for
+shoals and rocks; and the more the burthen of their ships increased,
+the more imperatively necessary it became for sailors to ascertain
+with precision the depth of the waters they traversed. Out of this
+necessity grew the use of the lead and sounding-line; and, ultimately,
+marine-surveying, which is the recording of the form of coasts and of
+the depth of the sea, as ascertained by the sounding-lead, upon
+charts.
+
+At the same time, it became desirable to ascertain and to indicate the
+nature of the sea-bottom, since this circumstance greatly affects its
+goodness as holding ground for anchors. Some ingenious tar, whose name
+deserves a better fate than the oblivion into which it has fallen,
+attained this object by "arming" the bottom of the lead with a lump of
+grease, to which more or less of the sand or mud, or broken shells, as
+the case might be, adhered, and was brought to the surface. But,
+however well adapted such an apparatus might be for rough nautical
+purposes, scientific accuracy could not be expected from the armed
+lead, and to remedy its defects (especially when applied to sounding
+in great depths) Lieutenant Brooke, of the American Navy, some years
+ago invented a most ingenious machine, by which a considerable portion
+of the superficial layer of the sea-bottom can be scooped out and
+brought up, from any depth to which the lead descends.
+
+In 1853, Lieutenant Brooke obtained mud from the bottom of the North
+Atlantic, between Newfoundland and the Azores, at a depth of more than
+ten thousand feet, or two miles, by the help of this sounding
+apparatus. The specimens were sent for examination to Ehrenberg of
+Berlin, and to Bailey of West Point, and those able microscopists
+found that this deep-sea mud was almost entirely composed of the
+skeletons of living organisms--the greater proportion of these being
+just like the Globigerinæ already known to occur in chalk.
+
+Thus far, the work had been carried on simply in the interests of
+science, but Lieutenant Brooke's method of sounding acquired a high
+commercial value, when the enterprise of laying down the
+telegraph-cable between this country and the United States was
+undertaken. For it became a matter of immense importance to know, not
+only the depth of the sea over the whole line, along which the cable
+was to be laid, but the exact nature of the bottom, so as to guard
+against chances of cutting or fraying the strands of that costly rope.
+The Admiralty consequently ordered Captain Dayman, an old friend and
+shipmate of mine, to ascertain the depth over the whole line of the
+cable, and to bring back specimens of the bottom. In former days, such
+a command as this might have sounded very much like one of the
+impossible things which the young prince in the Fairy Tales is ordered
+to do before he can obtain the hand of the princess. However, in the
+months of June and July, 1857, my friend performed the task assigned
+to him with great expedition and precision, without, so far as I know,
+having met with any reward of that kind. The specimens of Atlantic mud
+which he procured were sent to me to be examined and reported upon.
+
+The result of all these operations is, that we know the contours and
+the nature of the surface-soil covered by the North Atlantic, for a
+distance of seventeen hundred miles from east to west, as well as we
+know that of any part of the dry land.
+
+It is a prodigious plain--one of the widest and most even plains in
+the world. If the sea were drained off, you might drive a wagon all
+the way from Valentia, on the west coast of Ireland, to Trinity Bay in
+Newfoundland. And, except upon one sharp incline about two hundred
+miles from Valentia, I am not quite sure that it would even be
+necessary to put the skid on, so gentle are the ascents and descents
+upon that long route. From Valentia the road would lie down-hill for
+about two hundred miles to the point at which the bottom is now
+covered by seventeen hundred fathoms of sea-water. Then would come the
+central plain, more than a thousand miles wide, the inequalities of
+the surface of which would be hardly perceptible, though the depth of
+water upon it now varies from ten thousand to fifteen thousand feet;
+and there are places in which Mont Blanc might be sunk without showing
+its peak above water. Beyond this, the ascent on the American side
+commences, and gradually leads, for about three hundred miles, to the
+Newfoundland shore.
+
+Almost the whole of the bottom of this central plain (which extends
+for many hundred miles in a north and south direction) is covered by a
+fine mud, which, when brought to the surface, dries into a grayish
+white friable substance. You can write with this on a black-board, if
+you are so inclined; and, to the eye, it is quite like very soft,
+grayish chalk. Examined chemically, it proves to be composed almost
+wholly of carbonate of lime; and if you make a section of it, in the
+same way as that of the piece of chalk was made, and view it with the
+microscope, it presents innumerable Globigerinæ embedded in a granular
+matrix.
+
+Thus this deep-sea mud is substantially chalk. I say substantially,
+because there are a good many minor differences; but as these have no
+bearing on the question immediately before us--which is the nature of
+the Globigerinæ of the chalk--it is unnecessary to speak of them.
+
+Globigerinæ of every size, from the smallest to the largest, are
+associated together in the Atlantic mud, and the chambers of many are
+filled by a soft animal matter. This soft substance is, in fact, the
+remains of the creature to which the Globigerina shell, or rather
+skeleton, owes its existence--and which is an animal of the simplest
+imaginable description. It is, in fact, a mere particle of living
+jelly, without defined parts of any kind--without a mouth, nerves,
+muscles, or distinct organs, and only manifesting its vitality to
+ordinary observation by thrusting out and retracting from all parts of
+its surface long filamentous processes, which serve for arms and legs.
+Yet this amorphous particle, devoid of everything which, in the higher
+animals, we call organs, is capable of feeding, growing, and
+multiplying; of separating from the ocean the small proportion of
+carbonate of lime which is dissolved in sea-water; and of building up
+that substance into a skeleton for itself, according to a pattern
+which can be imitated by no other known agency.
+
+The notion that animals can live and flourish in the sea, at the vast
+depths from which apparently living Giobigerinæ have been brought up,
+does not agree very well with our usual conceptions respecting the
+conditions of animal life; and it is not so absolutely impossible as
+it might at first sight appear to be, that the Globigerinæ of the
+Atlantic sea-bottom do not live and die where they are found.
+
+[Illustration: DIATOM OOZE DREDGED FROM A DEPTH OF 1950 FEET.
+
+(Magnified nearly 300 diameters.)]
+
+As I have mentioned, the soundings from the great Atlantic plain are
+almost entirely made up of Globigerinæ, with the granules which have
+been mentioned, and some few other calcareous shells; but a small
+percentage of the chalky mud--perhaps at most some five per cent of
+it--is of a different nature, and consists of shells and skeletons
+composed of silex, or pure flint. These siliceous bodies belong partly
+to the lowly vegetable organisms which are called Diatomaceæ, and
+partly to the minute and extremely simple animals, termed Radiolaria.
+It is quite certain that these creatures do not live at the bottom of
+the ocean, but at its surface--where they may be obtained in
+prodigious numbers by the use of a properly constructed net. Hence it
+follows that these siliceous organisms, though they are not heavier
+than the lightest dust, must have fallen, in some cases, through
+fifteen thousand feet of water, before they reached their final
+resting-place on the ocean floor. And, considering how large a
+surface these bodies expose in proportion to their weight, it is
+probable that they occupy a great length of time in making their
+burial journey from the surface of the Atlantic to the bottom.
+
+[Illustration: RADIOLARIA. (_a._ Natural size. _b._ One-third natural
+size.)]
+
+But if the Radiolaria and Diatoms are thus rained upon the bottom of
+the sea, from the superficial layer of its waters in which they pass
+their lives, it is obviously possible that the Globigerinæ may be
+similarly derived; and if they were so, it would be much more easy to
+understand how they obtain their supply of food than it is at present.
+Nevertheless, the positive and negative evidence all points the other
+way. The skeletons of the full-grown, deep-sea Globigerinæ are so
+remarkably solid and heavy in proportion to their surface as to seem
+little fitted for floating; and, as a matter of fact, they are not to
+be found along with the Diatoms and Radiolaria, in the uppermost
+stratum of the open ocean.
+
+It has been observed, again, that the abundance of Globigerinæ, in
+proportion to other organisms of like kind, increases with the depth
+of the sea; and that deep-water Globigerinæ are larger than those
+which live in the shallower parts of the sea; and such facts negative
+the supposition that these organisms have been swept by currents from
+the shallows into the deeps of the Atlantic.
+
+It therefore seems to be hardly doubtful that these wonderful
+creatures live and die at the depths in which they are found.[1]
+
+[Footnote 1: During the cruise of H.M.S. Bull-dog, commanded by Sir
+Leopold M'Clintock, in 1860, living star-fish were brought up,
+clinging to the lowest part of the sounding-line, from a depth of 1260
+fathoms, midway between Cape Farewell, in Greenland, and the Rockall
+banks. Dr. Wallich ascertained that the sea-bottom at this point
+consisted of the ordinary Globigerina ooze, and that the stomachs of
+the star-fishes were full of Globigerinæ. This discovery removes all
+objections to the existence of living Globigerinæ at great depths,
+which are based upon the supposed difficulty of maintaining animal
+life under such conditions; and it throws the burden of proof upon
+those who object to the supposition that the Globigerinæ live and die
+where they are found.]
+
+However, the important points for us are, that the living Globigerinæ
+are exclusively marine animals, the skeletons of which abound at the
+bottom of deep seas; and that there is not a shadow of reason for
+believing that the habits of the Globigerinæ of the chalk differed
+from those of the existing species. But if this be true, there is no
+escaping the conclusion that the chalk itself is the dried mud of an
+ancient deep sea.
+
+In working over the soundings collected by Captain Dayman, I was
+surprised to find that many of what I have called the "granules" of
+that mud were not, as one might have been tempted to think at first,
+the mere powder and waste of Globigerinæ, but that they had a definite
+form and size. I termed these bodies "_coccoliths_" and doubted their
+organic nature. Dr. Wallich verified my observation, and added the
+interesting discovery that, not unfrequently, bodies similar to these
+"coccoliths" were aggregated together into spheroids, which he termed
+"_coccospheres_." So far as we knew, these bodies, the nature of which
+is extremely puzzling and problematical, were peculiar to the
+Atlantic soundings.
+
+But, a few years ago, Mr. Sorby, in making a careful examination of
+the chalk by means of thin sections and otherwise, observed, as
+Ehrenberg had done before him, that much of its granular basis
+possesses a definite form. Comparing these formed particles with those
+in the Atlantic soundings, he found the two to be identical; and thus
+proved that the chalk, like the soundings, contains these mysterious
+coccoliths and coccospheres. Here was a further and a most interesting
+confirmation, from internal evidence, of the essential identity of the
+chalk with modern deep-sea mud. Globigerinæ, coccoliths, and
+coccospheres are found as the chief constituents of both, and testify
+to the general similarity of the conditions under which both have been
+formed.[2]
+
+[Footnote 2: I have recently traced out the development of the
+"coccoliths" from a diameter of 1/7000th of an inch up to their
+largest size (which is about 1/1600th), and no longer doubt that they
+are produced by independent organisms, which, like the Globigerinæ,
+live and die at the bottom of the sea.]
+
+The evidence furnished by the hewing, facing, and superposition of the
+stones of the Pyramids, that these structures were built by men, has
+no greater weight than the evidence that the chalk was built by
+Globigerinæ; and the belief that those ancient pyramid-builders were
+terrestrial and air-breathing creatures like ourselves, is not better
+based than the conviction that the chalk-makers lived in the sea.
+
+But as our belief in the building of the Pyramids by men is not only
+grounded on the internal evidence afforded by these structures, but
+gathers strength from multitudinous collateral proofs, and is clinched
+by the total absence of any reason for a contrary belief; so the
+evidence drawn from the Globigerinæ that the chalk is an ancient
+sea-bottom, is fortified by innumerable independent lines of evidence;
+and our belief in the truth of the conclusion to which all positive
+testimony tends, receives the like negative justification from the
+fact that no other hypothesis has a shadow of foundation.
+
+It may be worth while briefly to consider a few of these collateral
+proofs that the chalk was deposited at the bottom of the sea.
+
+The great mass of the chalk is composed, as we have seen, of the
+skeletons of Globigerinæ, and other simple organisms, imbedded in
+granular matter. Here and there, however, this hardened mud of the
+ancient sea reveals the remains of higher animals which have lived and
+died, and left their hard parts in the mud, just as the oysters die
+and leave their shells behind them, in the mud of the present seas.
+
+[Illustration: UPPER SILURIAN CORALS AND CRUSTACEANS.]
+
+There are, at the present day, certain groups of animals which are
+never found in fresh waters, being unable to live anywhere but in the
+sea. Such are the corals; those corallines which are called Polyzoa;
+those creatures which fabricate the lamp-shells, and are called
+Brachiopoda; the pearly Nautilus, and all animals allied to it; and
+all the forms of sea-urchins and star-fishes.
+
+Not only are all these creatures confined to salt water at the present
+day, but, so far as our records of the past go, the conditions of
+their existence have been the same: hence, their occurrence in any
+deposit is as strong evidence as can be obtained, that that deposit
+was formed in the sea. Now the remains of animals of all the kinds
+which have been enumerated occur in the chalk, in greater or less
+abundance; while not one of those forms of shell-fish which are
+characteristic of fresh water has yet been observed in it.
+
+When we consider that the remains of more than three thousand distinct
+species of aquatic animals have been discovered among the fossils of
+the chalk, that the great majority of them are of such forms as are
+now met with only in the sea, and that there is no reason to believe
+that any one of them inhabited fresh water--the collateral evidence
+that the chalk represents an ancient sea-bottom acquires as great
+force as the proof derived from the nature of the chalk itself. I
+think you will now allow that I did not overstate my case when I
+asserted that we have as strong grounds for believing that all the
+vast area of dry land at present occupied by the chalk was once at the
+bottom of the sea, as we have for any matter of history whatever;
+while there is no justification for any other belief.
+
+[Illustration: CRETACEOUS NAUTILUS.]
+
+No less certain is it that the time during which the countries we now
+call southeast England, France, Germany, Poland, Russia, Egypt,
+Arabia, Syria, were more or less completely covered by a deep sea,
+was of considerable duration.
+
+We have already seen that the chalk is, in places, more than a
+thousand feet thick. I think you will agree with me that it must have
+taken some time for the skeletons of the animalcules of a hundredth of
+an inch in diameter to heap up such a mass as that. I have said that
+throughout the thickness of the chalk the remains of other animals are
+scattered. These remains are often in the most exquisite state of
+preservation. The valves of the shell-fishes are commonly adherent;
+the long spines of some of the sea-urchins, which would be detached by
+the smallest jar, often remain in their places. In a word, it is
+certain that these animals have lived and died when the place which
+they now occupy was the surface of as much of the chalk as had then
+been deposited; and that each has been covered up by the layer of
+Globigerina mud, upon which the creatures imbedded a little higher up
+have, in like manner, lived and died. But some of these remains prove
+the existence of reptiles of vast size in the chalk sea. These lived
+their time, and had their ancestors and descendants, which assuredly
+implies time, reptiles being of slow growth.
+
+There is more curious evidence, again, that the process of covering
+up, or, in other words, the deposit of Globigerina skeletons, did not
+go on very fast. It is demonstrable that an animal of the cretaceous
+sea might die, that its skeleton might lie uncovered upon the
+sea-bottom long enough to lose all its outward coverings and
+appendages by putrefaction; and that, after this had happened, another
+animal might attach itself to the dead and naked skeleton, might grow
+to maturity, and might itself die before the calcareous mud had buried
+the whole.
+
+Cases of this kind are admirably described by Sir Charles Lyell. He
+speaks of the frequency with which geologists find in the chalk a
+fossilized sea-urchin to which is attached the lower valve of a
+Crania. This is a kind of shell-fish, with a shell composed of two
+pieces, of which, as in the oyster, one is fixed and the other free.
+
+"The upper valve is almost invariably wanting, though occasionally
+found in a perfect state of preservation in the white chalk at some
+distance. In this case, we see clearly that the sea-urchin first lived
+from youth to age, then died and lost its spines, which were carried
+away. Then the young Crania adhered to the bared shell, grew and
+perished in its turn; after which, the upper valve was separated from
+the lower, before the Echinus became enveloped in chalky mud."
+
+A specimen in the Museum of Practical Geology, in London, still
+further prolongs the period which must have elapsed between the death
+of the sea-urchin and its burial by the Globigeringæ. For the outward
+face of the valve of a Crania, which is attached to a sea-urchin
+(Micrastor), is itself overrun by an incrusting coralline, which
+spreads thence over more or less of the surface of the sea-urchin. It
+follows that, after the upper valve of the Crania fell off, the
+surface of the attached valve must have remained exposed long enough
+to allow of the growth of the whole coralline, since corallines do not
+live imbedded in the mud.
+
+The progress of knowledge may, one day, enable us to deduce from such
+facts as these the maximum rate at which the chalk can have
+accumulated, and thus to arrive at the minimum duration of the chalk
+period. Suppose that the valve of the Crania upon which a coralline
+has fixed itself in the way just described is so attached to the
+sea-urchin that no part of it is more than an inch above the face upon
+which the sea-urchin rests. Then, as the coralline could not have
+fixed itself if the Crania had been covered up with chalk-mud, and
+could not have lived had itself been so covered, it follows, that an
+inch of chalk mud could not have accumulated within the time between
+the death and decay of the soft parts of the sea-urchin and the growth
+of the coralline to the full size which it has attained. If the decay
+of the soft parts of the sea-urchin; the attachment, growth to
+maturity, and decay of the Crania; and the subsequent attachment and
+growth of the coralline, took a year (which is a low estimate enough),
+the accumulation of the inch of chalk must have taken more than a
+year: and the deposit of a thousand feet of chalk must, consequently,
+have taken more than twelve thousand years.
+
+The foundation of all this calculation is, of course, a knowledge of
+the length of time the Crania and the coralline needed to attain their
+full size; and, on this head, precise knowledge is at present wanting.
+But there are circumstances which tend to show that nothing like an
+inch of chalk has accumulated during the life of a Crania; and, on any
+probable estimate of the length of that life, the chalk period must
+have had a much longer duration than that thus roughly assigned to
+it.
+
+Thus, not only is it certain that the chalk is the mud of an ancient
+sea-bottom; but it is no less certain that the chalk sea existed
+during an extremely long period, though we may not be prepared to give
+a precise estimate of the length of that period in years. The relative
+duration is clear, though the absolute duration may not be definable.
+The attempt to affix any precise date to the period at which the chalk
+sea began or ended its existence, is baffled by difficulties of the
+same kind. But the relative age of the cretaceous epoch may be
+determined with as great ease and certainty as the long duration of
+that epoch.
+
+You will have heard of the interesting discoveries recently made, in
+various parts of Western Europe, of flint implements, obviously worked
+into shape by human hands, under circumstances which show conclusively
+that man is a very ancient denizen of these regions.
+
+It has been proved that the old populations of Europe, whose existence
+has been revealed to us in this way, consisted of savages, such as the
+Esquimaux are now; that, in the country which is now France, they
+hunted the reindeer, and were familiar with the ways of the mammoth
+and the bison. The physical geography of France was in those days
+different from what it is now--the river Somme, for instance, having
+cut its bed a hundred feet deeper between that time and this; and it
+is probable that the climate was more like that of Canada or Siberia
+than that of Western Europe.
+
+The existence of these people is forgotten even in the traditions of
+the oldest historical nations. The name and fame of them had utterly
+vanished until a few years back; and the amount of physical change
+which has been effected since their day renders it more than probable
+that, venerable as are some of the historical nations, the workers of
+the chipped flints of Hoxne or of Amiens are to them, as they are to
+us, in point of antiquity.
+
+But, if we assign to these hoar relics of long-vanished generations of
+men the greatest age that can possibly be claimed for them, they are
+not older than the drift, or boulder clay, which, in comparison with
+the chalk, is but a very juvenile deposit. You need go no further than
+your own seaboard for evidence of this fact. At one of the most
+charming spots on the coast of Norfolk, Cromer, you will see the
+boulder clay forming a vast mass, which lies upon the chalk, and must
+consequently have come into existence after it. Huge boulders of chalk
+are, in fact, included in the clay, and have evidently been brought to
+the position they now occupy by the same agency as that which has
+planted blocks of syenite from Norway side by side with them.
+
+The chalk, then, is certainly older than the boulder clay. If you ask
+how much, I will again take you no further than the same spot upon
+your own coasts for evidence. I have spoken of the boulder clay and
+drift as resting upon the chalk. That is not strictly true. Interposed
+between the chalk and the drift is a comparatively insignificant
+layer, containing vegetable matter. But that layer tells a wonderful
+history. It is full of stumps of trees standing as they grew.
+Fir-trees are there with their cones, and hazel-bushes with their
+nuts; there stand the stools of oak and yew trees, beeches and
+alders. Hence this stratum is appropriately called the "forest-bed."
+
+It is obvious that the chalk must have been upheaved and converted
+into dry land before the timber trees could grow upon it. As the bolls
+of some of these trees are from two to three feet in diameter, it is
+no less clear that the dry land thus formed remained in the same
+condition for long ages. And not only do the remains of stately oaks
+and well-grown firs testify to the duration of this condition of
+things, but additional evidence to the same effect is afforded by the
+abundant remains of elephants, rhinoceroses, hippopotamuses, and other
+great wild beasts, which it has yielded to the zealous search of such
+men as the Rev. Mr. Gunn.
+
+When you look at such a collection as he has formed, and bethink you
+that these elephantine bones did veritably carry their owners about,
+and these great grinders crunch, in the dark woods of which the
+forest-bed is now the only trace, it is impossible not to feel that
+they are as good evidence of the lapse of time as the annual rings of
+the tree-stumps.
+
+Thus there is a writing upon the wall of cliffs at Cromer, and whoso
+runs may read it. It tells us, with an authority which cannot be
+impeached, that the ancient sea-bed of the chalk sea was raised up,
+and remained dry land, until it was covered with forest, stocked with
+the great game whose spoils have rejoiced your geologists. How long it
+remained in that condition cannot be said; but "the whirligig of time
+brought its revenges" in those days as in these. That dry land, with
+the bones and teeth of generations of long-lived elephants, hidden
+away among the gnarled roots and dry leaves of its ancient trees, sank
+gradually to the bottom of the icy sea, which covered it with huge
+masses of drift and boulder clay. Sea-beasts, such as the walrus, now
+restricted to the extreme north, paddled about where birds had
+twittered among the topmost twigs of the fir-trees. How long this
+state of things endured we know not, but at length it came to an end.
+The upheaved glacial mud hardened into the soil of modern Norfolk.
+Forests grew once more, the wolf and the beaver replaced the reindeer
+and the elephant; and at length what we call the history of England
+dawned.
+
+Thus you have, within the limits of your own county, proof that the
+chalk can justly claim a very much greater antiquity than even the
+oldest physical traces of mankind. But we may go further and
+demonstrate, by evidence of the same authority as that which testifies
+to the existence of the father of men, that the chalk is vastly older
+than Adam himself.
+
+The Book of Genesis informs us that Adam, immediately upon his
+creation, and before the appearance of Eve, was placed in the garden
+of Eden. The problem of the geographical position of Eden has greatly
+vexed the spirits of the learned in such matters, but there is one
+point respecting which, so far as I know, no commentator has ever
+raised a doubt. This is, that of the four rivers which are said to run
+out of it, Euphrates and Hiddekel are identical with the rivers now
+known by the names of Euphrates and Tigris.
+
+But the whole country in which these mighty rivers take their origin,
+and through which they run, is composed of rocks which are either of
+the same age as the chalk, or of later date. So that the chalk must
+not only have been formed, but, after its formation, the time required
+for the deposit of these later rocks, and for their upheaval into dry
+land, must have elapsed, before the smallest brook which feeds the
+swift stream of "the great river, the river of Babylon," began to
+flow.
+
+       *       *       *       *       *
+
+Thus, evidence which cannot be rebutted, and which need not be
+strengthened, though if time permitted I might indefinitely increase
+its quantity, compels you to believe that the earth, from the time of
+the chalk to the present day, has been the theatre of a series of
+changes as vast in their amount as they were slow in their progress.
+The area on which we stand has been first sea and then land, for at
+least four alternations; and has remained in each of these conditions
+for a period of great length.
+
+Nor have these wonderful metamorphoses of sea into land, and of land
+into sea, been confined to one corner of England. During the chalk
+period, or "cretaceous epoch," not one of the present great physical
+features of the globe was in existence. Our great mountain ranges,
+Pyrenees, Alps, Himalayas, Andes, have all been upheaved since the
+chalk was deposited, and the cretaceous sea flowed over the sites of
+Sinai and Ararat.
+
+All this is certain, because rocks of cretaceous or still later date
+have shared in the elevatory movements which gave rise to these
+mountain chains; and may be found perched up, in some cases, many
+thousand feet high upon their flanks. And evidence of equal cogency
+demonstrates that, though in Norfolk the forest-bed rests directly
+upon the chalk, yet it does so, not because the period at which the
+forest grew immediately followed that at which the chalk was formed,
+but because an immense lapse of time, represented elsewhere by
+thousands of feet of rock, is not indicated at Cromer.
+
+I must ask you to believe that there is no less conclusive proof that
+a still more prolonged succession of similar changes occurred before
+the chalk was deposited. Nor have we any reason to think that the
+first term in the series of these changes is known. The oldest
+sea-beds preserved to us are sands, and mud, and pebbles, the wear and
+tear of rocks which were formed in still older oceans.
+
+But, great as is the magnitude of these physical changes of the world,
+they have been accompanied by a no less striking series of
+modifications in its living inhabitants.
+
+All the great classes of animals, beasts of the field, fowls of the
+air, creeping things, and things which dwell in the waters, flourished
+upon the globe long ages before the chalk was deposited. Very few,
+however, if any, of these ancient forms of animal life were identical
+with those which now live. Certainly not one of the higher animals was
+of the same species as any of those now in existence. The beasts of
+the field, in the days before the chalk, were not our beasts of the
+field, nor the fowls of the air such as those which the eye of man has
+seen flying, unless his antiquity dates infinitely further back than
+we at present surmise. If we could be carried back into those times,
+we should be as one suddenly set down in Australia before it was
+colonized. We should see mammals, birds, reptiles, fishes, insects,
+snails, and the like, clearly recognizable as such, and yet not one of
+them would be just the same as those with which we are familiar, and
+many would be extremely different.
+
+From that time to the present, the population of the world has
+undergone slow and gradual, but incessant, changes. There has been no
+grand catastrophe--no destroyer has swept away the forms of life of
+one period, and replaced them by a totally new creation; but one
+species has vanished and another has taken its place; creatures of one
+type of structure have diminished, those of another have increased, as
+time has passed on. And thus, while the differences between the living
+creatures of the time before the chalk and those of the present day
+appear startling, if placed side by side, we are led from one to the
+other by the most gradual progress, if we follow the course of Nature
+through the whole series of those relics of her operations which she
+has left behind.
+
+[Illustration: SKELETON OF THE PTERODACTYL.]
+
+And it is by the population of the chalk sea that the ancient and the
+modern inhabitants of the world are most completely connected. The
+groups which are dying out flourish, side by side, with the groups
+which are now the dominant forms of life.
+
+Thus the chalk contains remains of those flying and swimming
+reptiles, the pterodactyl, the ichthyosaurus, and the plesiosaurus,
+which are found in no later deposits, but abounded in preceding ages.
+The chambered shells called ammonites and belemnites, which are so
+characteristic of the period preceding the cretaceous, in like manner
+die with it.
+
+[Illustration: THE SKELETON OF THE ICHTHYOSAURUS.]
+
+[Illustration: THE SKELETON OF THE PLESIOSAURUS.]
+
+[Illustration: AMMONITES.]
+
+But, among these fading remainders of a previous state of things, are
+some very modern forms of life, looking like Yankee peddlers among a
+tribe of red Indians. Crocodiles of modern type appear; bony fishes,
+many of them very similar to existing species, almost supplant the
+forms of fish which predominate in more ancient seas; and many kinds
+of living shell-fish first become known to us in the chalk. The
+vegetation acquires a modern aspect. A few living animals are not even
+distinguishable as species from those which existed at that remote
+epoch. The Globigerina of the present day, for example, is not
+different specifically from that of the chalk; and the same may be
+said of many other Foraminifera. I think it probable that critical and
+unprejudiced examination will show that more than one species of much
+higher animals have had a similar longevity; but the only example
+which I can at present give confidently is the snake's-head lamp-shell
+(_Terebratulina caput serpentis_), which lives in our English seas and
+abounded (as _Terebratulina striata_ of authors) in the chalk.
+
+[Illustration: BELEMNITES.]
+
+[Illustration: TEREBRATULINA.]
+
+The longest line of human ancestry must hide its diminished head
+before the pedigree of this insignificant shell-fish. We Englishmen
+are proud to have an ancestor who was present at the Battle of
+Hastings. The ancestors of _Terebratulina caput serpentis_ may have
+been present at a battle of Ichthyosauria in that part of the sea
+which, when the chalk was forming, flowed over the site of Hastings.
+While all around has changed, this Terebratulina has peacefully
+propagated its species from generation to generation, and stands to
+this day as a living testimony to the continuity of the present with
+the past history of the globe.
+
+       *       *       *       *       *
+
+Up to this moment I have stated, so far as I know, nothing but
+well-authenticated facts, and the immediate conclusions which they
+force upon the mind.
+
+But the mind is so constituted that it does not willingly rest in
+facts and immediate causes, but seeks always after a knowledge of the
+remoter links in the chain of causation.
+
+Taking the many changes of any given spot of the earth's surface, from
+sea to land, and from land to sea, as an established fact, we cannot
+refrain from asking ourselves how these changes have occurred. And
+when we have explained them--as they must be explained--by the
+alternate slow movements of elevation and depression which have
+affected the crusts of the earth, we go still further back, and ask,
+Why these movements?
+
+I am not certain that any one can give you a satisfactory answer to
+that question. Assuredly I cannot. All that can be said for certain
+is, that such movements are part of the ordinary course of nature,
+inasmuch as they are going on at the present time. Direct proof may be
+given, that some parts of the land of the northern hemisphere are at
+this moment insensibly rising and others insensibly sinking; and there
+is indirect but perfectly satisfactory proof, that an enormous area
+now covered by the Pacific has been deepened thousands of feet since
+the present inhabitants of that sea came into existence.
+
+Thus there is not a shadow of a reason for believing that the
+physical changes of the globe, in past times, have been effected by
+other than natural causes.
+
+Is there any more reason for believing that the concomitant
+modifications in the forms of the living inhabitants of the globe have
+been brought about in any other ways?
+
+Before attempting to answer this question, let us try to form a
+distinct mental picture of what has happened in some special case.
+
+The crocodiles are animals which, as a group, have a very vast
+antiquity. They abounded ages before the chalk was deposited; they
+throng the rivers in warm climates at the present day. There is a
+difference in the form of the joints of the backbone, and in some
+minor particulars, between the crocodiles of the present epoch and
+those which lived before the chalk; but, in the cretaceous epoch, as I
+have already mentioned, the crocodiles had assumed the modern type of
+structure. Notwithstanding this, the crocodiles of the chalk are not
+identically the same as those which lived in the times called "older
+tertiary," which succeeded the cretaceous epoch; and the crocodiles of
+the older tertiaries are not identical with those of the newer
+tertiaries, nor are these identical with existing forms. I leave open
+the question whether particular species may have lived on from epoch
+to epoch. But each epoch has had its peculiar crocodiles; though all,
+since the chalk, have belonged to the modern type, and differ simply
+in their proportions and in such structural particulars as are
+discernible only to trained eyes.
+
+How is the existence of this long succession of different species of
+crocodiles to be accounted for?
+
+Only two suppositions seem to be open to us--either each species of
+crocodile has been specially created, or it has arisen out of some
+pre-existing form by the operation of natural causes.
+
+Choose your hypothesis; I have chosen mine. I can find no warranty for
+believing in the distinct creation of a score of successive species of
+crocodiles in the course of countless ages of time. Science gives no
+countenance to such a wild fancy; nor can even the perverse ingenuity
+of a commentator pretend to discover this sense, in the simple wrords
+in which the writer of Genesis records the proceeding of the fifth and
+sixth days of the Creation.
+
+On the other hand, I see no good reason for doubting the necessary
+alternative, that all these varied species have been evolved from
+pre-existing crocodilian forms by the operation of causes as
+completely a part of the common order of nature as those which have
+effected the changes of the inorganic world.
+
+Few will venture to affirm that the reasoning which applies to
+crocodiles loses its force among other animals or among plants. If one
+series of species has come into existence by the operation of natural
+causes, it seems folly to deny that all may have arisen in the same
+way.
+
+       *       *       *       *       *
+
+A small beginning has led us to a great ending. If I were to put the
+bit of chalk with which we started into the hot but obscure flame of
+burning hydrogen, it would presently shine like the sun. It seems to
+me that this physical metamorphosis is no false image of what has been
+the result of our subjecting it to a jet of fervent, though nowise
+brilliant, thought to-night. It has become luminous, and its clear
+rays, penetrating the abyss of the remote past, have brought within
+our ken some stages of the evolution of the earth. And in the shifting
+"without haste, but without rest" of the land and sea, as in the
+endless variation of the forms assumed by living beings, we have
+observed nothing but the natural product of the forces originally
+possessed by the substance of the universe.
+
+[Illustration]
+
+
+
+
+A BIT OF SPONGE
+
+(Written on Scotland.)
+
+(FROM GLIMPSES OF NATURE.)
+
+BY A. WILSON.
+
+
+[Illustration]
+
+This morning, despite the promise of rain over-night, has broken with
+all the signs and symptoms of a bright July day. The Firth is bathed
+in sunlight, and the wavelets at full tide are kissing the strand,
+making a soft musical ripple as they retire, and as the pebbles run
+down the sandy slope on the retreat of the waves. Beyond the farthest
+contact of the tide is a line of seaweed dried and desiccated, mixed
+up with which, in confusing array, are masses of shells, and such
+_olla podrida_ of the sea.
+
+Tossed up at our very feet is a dried fragment of sponge, which
+doubtless the unkind waves tore from its rocky bed. It is not a large
+portion of sponge this, but its structure is nevertheless to be fairly
+made out, and some reminiscences of its history gleaned, for the sake
+of occupying the by no means "bad half-hour" before breakfast. "What
+is a sponge?" is a question which you may well ask as a necessary
+preliminary to the understanding of its personality.
+
+[Illustration: A SPONGE ATTACHED TO ITS ROCKY BED.]
+
+The questionings of childhood and the questionings of science run in
+precisely similar grooves. "What is it?" and "How does it live?" and
+"Where does it come from?" are equally the inquiries of childhood, and
+of the deepest philosophy which seeks to determine the whole history
+of life. This morning, we cannot do better than follow in the
+footsteps of the child, and to the question, "What is a sponge?" I
+fancy science will be able to return a direct answer. First of all, we
+may note that a sponge, as we know it in common life, is the horny
+skeleton or framework which was made by, and which supported, the
+living parts. These living parts consist of minute masses of that
+living jelly to which the name of _protoplasm_ has been applied. This,
+in truth, is the universal matter of life. It is the one substance
+with which life everywhere is associated, and as we see it simply in
+the sponge, so also we behold it (only in more complex guise) in the
+man. Now, the living parts of this dried cast-away sponge were found
+both in its interior and on its surface. They lined the canals that
+everywhere permeate the sponge-substance, and microscopic examination
+has told us a great deal about their nature.
+
+
+[Illustration: FIG. 1. DEVELOPMENT OF A SPONGE (_Olynthus_). 1. The
+egg. 2, 3, and 4. The process of egg-division. 5 and 6. The
+gastrula-stage. 7. The perfect sponge.]
+
+For, whether found in the canals of the sponge themselves, or embedded
+in the sponge-substance, the living sponge-particles are represented
+each by a semi-independent mass of protoplasm. So that the first view
+I would have you take of the sponge as a living mass, is, that it is a
+colony and not a single unit. It is composed, in other words, of
+aggregated masses of living particles, which bud out one from the
+other, and manufacture the supporting skeleton we know as "the sponge
+of commerce" itself. Under the microscope, these living sponge-units
+appear in various guises and shapes. Some of them are formless, and,
+as to shape, ever-altering masses, resembling that familiar animalcule
+of our pools we know as the _Amoeba_. These members of the
+sponge-colony form the bulk of the population. They are embedded in
+the sponge substance; they wander about through the meshes of the
+sponge; they seize food and flourish and grow; and they probably also
+give origin to the "eggs" from which new sponges are in due course
+produced.
+
+More characteristic however, are certain units of this living
+sponge-colony which live in the lining membrane of the canals. In
+point of fact, a sponge is a kind of Venice, a certain proportion of
+whose inhabitants, like those of the famous Queen of the Adriatic
+herself, live on the banks of the waterways. Just as in Venice we find
+the provisions for the denizens of the city brought to the inhabitants
+by the canals, so from the water, which, as we shall see, is
+perpetually circulating through a sponge, the members of the
+sponge-colony receive their food.
+
+Look, again, at the sponge-fragment which lies before us. You perceive
+half a dozen large holes or so, each opening on a little eminence, as
+it were. These apertures, bear in mind, we call _oscula_. They are the
+exits of the sponge-domain. But a close inspection of a sponge shows
+that it is riddled with finer and smaller apertures. These latter are
+the _pores_, and they form the entrances to the sponge-domain.
+
+On the banks of the canal you may see growing plentifully in summer
+time a green sponge, which is the common fresh-water species. Now, if
+you drop a living specimen of this species into a bowl of water, and
+put some powdered indigo into the water, you may note how the currents
+are perpetually being swept in by the pores and out by the oscula. In
+every living sponge this perpetual and unceasing circulation of water
+proceeds. This is the sole evidence the unassisted sight receives of
+the vitality of the sponge-colony, and the importance of this
+circulation in aiding life in these depths, to be fairly carried out
+cannot readily be over-estimated.
+
+[Illustration: WHERE SPONGES GROW.]
+
+Let us now see how this circulation is maintained. Microscopically
+regarded, we see here and there, in the sides of the sponge-passages,
+little chambers and recesses which remind one of the passing-places in
+a narrow canal. Lining these chambers, we see living sponge-units of a
+type different from the shapeless specks we noted to occur in the
+meshes of the sponge substance itself. The units of the recesses each
+consist of a living particle, whose free extremity is raised into a
+kind of collar, from which projects a lash-like filament known as a
+flagellum.
+
+This lash is in constant movement. It waves to and fro in the water,
+and the collection of lashes we see in any one chamber acts as a
+veritable brush, which by its movement not only sweeps water in by the
+pores, but sends it onwards through the sponge, and in due time sends
+it out by the bigger holes, or oscula. This constant circulation in
+the sponge discharges more than one important function. For, as
+already noted, it serves the purpose of nutrition, in that the
+particles on which sponge-life is supported are swept into the colony.
+
+Again, the fresh currents of water carry with them the oxygen gas
+which is a necessity of sponge existence, as of human life; while,
+thirdly, waste matters, inevitably alike in sponge and in man as the
+result of living, are swept out of the colony, and discharged into the
+sea beyond. Our bit of sponge has thus grown from a mere dry fragment
+into a living reality. It is a community in which already, low as it
+is, the work of life has come to be discharged by distinct and fairly
+specialized beings.
+
+The era of new sponge-life is inaugurated by means of egg-development,
+although there exists another fashion (that of gemmules or buds)
+whereby out of the parental substance young sponges are produced. A
+sponge-egg develops, as do all eggs, in a definite cycle. It undergoes
+division (Fig. 1); its one cell becomes many; and its many cells
+arrange themselves first of all into a cup-like form (5, 6 and 7),
+which may remain in this shape if the sponge is a simple one, or
+become developed into the more complex shape of the sponges we know.
+
+In every museum you may see specimens of a beautiful vase-like
+structure seemingly made of spun-glass. This is a flinty sponge, the
+"Venus flower-basket," whose presence in the sponge family redeems it
+from the charge that it contains no things of beauty whatever. So,
+too, the rocks are full of fossil-sponges, many of quaint form. Our
+piece of sponge, as we may understand, has yet other bits of history
+attached to it.... Meanwhile, think over the sponge and its ways, and
+learn from it that out of the dry things of life, science weaves many
+a fairy tale.
+
+[Illustration]
+
+
+
+
+THE GREATEST SEA-WAVE EVER KNOWN
+
+(FROM LIGHT SCIENCE IN LEISURE HOURS.)
+
+BY R.A. PROCTOR.
+
+
+[Illustration]
+
+August 13th, 1868, one of the most terrible calamities which has ever
+visited a people befell the unfortunate inhabitants of Peru. In that
+land earthquakes are nearly as common as rain storms are with us; and
+shocks by which whole cities are changed into a heap of ruins are by
+no means infrequent. Yet even in Peru, "the land of earthquakes," as
+Humboldt has termed it, no such catastrophe as that of August, 1868,
+had occurred within the memory of man. It was not one city which was
+laid in ruins, but a whole empire. Those who perished were counted by
+tens of thousands, while the property destroyed by the earthquake was
+valued at millions of pounds sterling.
+
+Although so many months have passed since this terrible calamity took
+place, scientific men have been busily engaged, until quite recently,
+in endeavoring to ascertain the real significance of the various
+events which were observed during and after the occurrence of the
+earthquake. The geographers of Germany have taken a special interest
+in interpreting the evidence afforded by this great manifestation of
+Nature's powers. Two papers have been written recently on the great
+earthquake of August 13th, 1868--one by Professor von Hochsteter, the
+other by Herr von Tschudi, which present an interesting account of the
+various effects, by land and by sea, which resulted from the
+tremendous upheaving force to which the western flanks of the Peruvian
+Andes were subjected on that day. The effects on land, although
+surprising and terrible, only differ in degree from those which have
+been observed in other earthquakes. But the progress of the great
+sea-wave which was generated by the upheaval of the Peruvian shores
+and propagated over the whole of the Pacific Ocean differs altogether
+from any earthquake phenomena before observed. Other earthquakes have
+indeed been followed by oceanic disturbances; but these have been
+accompanied by terrestrial motions, so as to suggest the idea that
+they had been caused by the motion of the sea-bottom or of the
+neighboring land. In no instance has it ever before been known that a
+well-marked wave of enormous proportions should have been propagated
+over the largest ocean tract on our globe by an earth-shock whose
+direct action was limited to a relatively small region, and that
+region not situated in the centre, but on one side of the wide area
+traversed by the wave.
+
+We propose to give a brief sketch of the history of this enormous
+sea-wave. In the first place, however, it may be well to remind the
+reader of a few of the more prominent features of the great shock to
+which this wave owed its origin.
+
+It was at Arequipa, at the foot of the lofty volcanic mountain Misti,
+that the most terrible effects of the great earthquake were
+experienced. Within historic times Misti has poured forth no lava
+streams, but that the volcano is not extinct is clearly evidenced by
+the fact that in 1542 an enormous mass of dust and ashes was vomited
+forth from its crater. On August 13th. 1868, Misti showed no signs of
+being disturbed. So far as the volcanic neighbor was concerned, the
+forty-four thousand inhabitants of Arequipa had no reason to
+anticipate the catastrophe which presently befell them. At five
+minutes past five an earthquake shock was experienced, which, though
+severe, seems to have worked little mischief. Half a minute later,
+however, a terrible noise was heard beneath the earth; a second shock
+more violent than the first was felt, and then began a swaying motion,
+gradually increasing in intensity. In the-course of the first minute
+this motion had become so violent that the inhabitants ran in terror
+out of their houses into the streets and squares. In the next two
+minutes the swaying movement had so increased that the more lightly
+built houses were cast to the ground, and the flying people could
+scarcely keep their feet. "And now," says Von Tschudi, "there followed
+during two or three minutes a terrible scene. The swaying motion which
+had hitherto prevailed changed into fierce vertical upheaval. The
+subterranean roaring increased in the most terrifying manner; then
+were heard the heart-piercing shrieks of the wretched people, the
+bursting of walls, the crashing fall of houses and churches, while
+over all rolled thick clouds of a yellowish-black dust, which, had
+they been poured forth many minutes longer, would have suffocated
+thousands." Although the shocks had lasted but a few minutes, the whole
+town was destroyed. Not one building remained uninjured, and there
+were few which did not lie in shapeless heaps of ruins.
+
+At Tacna and Arica the earth-shock was less severe, but strange and
+terrible phenomena followed it. At the former place a circumstance
+occurred the cause and nature of which yet remain a mystery. About
+three hours after the earthquake--in other words, at about eight
+o'clock in the evening--an intensely brilliant light made its
+appearance above the neighboring mountains. It lasted for fully half
+an hour, and has been ascribed to the eruption of some as yet unknown
+volcano.
+
+At Arica the sea-wave produced even more destructive effects than had
+been caused by the earthquake. About twenty minutes after the first
+earth-shock the sea was seen to retire, as if about to leave the
+shores wholly dry; but presently its waters returned with tremendous
+force. A mighty wave, whose length seemed immeasurable, was seen
+advancing like a dark wall upon the unfortunate town, a large part of
+which was overwhelmed by it. Two ships, the Peruvian corvette America,
+and the United States "double-ender" Wateree, were carried nearly half
+a mile to the north of Arica beyond the railroad which runs to Tacna,
+and there left stranded high and dry. This enormous wave was
+considered by the English vice-consul at Arica to have been fully
+fifty feet in height.
+
+At Chala three such waves swept in after the first shocks of
+earthquake. They overflowed nearly the whole of the town, the sea
+passing more than half a mile beyond its usual limits.
+
+At Islay and Iquique similar phenomena were manifested. At the former
+town the lava flowed in no less than five times, and each time with
+greater force. Afterward the motion gradually diminished, but even an
+hour and a half after the commencement of this strange disturbance the
+waves still ran forty feet above the ordinary level. At Iquique the
+people beheld the inrushing wave while it was still a great way off. A
+dark blue mass of water some fifty feet in height was seen sweeping in
+upon the town with inconceivable rapidity. An island lying before the
+harbor was completely submerged by the great wave, which still came
+rushing on black with the mud and slime it had swept from the
+sea-bottom. Those who witnessed its progress from the upper balconies
+of their houses, and presently saw its black mass rushing close
+beneath their feet, looked on their safety as a miracle. Many
+buildings were indeed washed away, and in the low-lying parts of the
+town there was a terrible loss of life. After passing far inland, the
+wave slowly returned sea-ward, and, strangely enough, the sea, which
+elsewhere heaved and tossed for hours after the first great wave had
+swept over it, here came soon to rest.
+
+At Callao a yet more singular instance was afforded of the effect
+which circumstances may have upon the motion of the sea after a great
+earthquake has disturbed it. In former earthquakes Callao has suffered
+terribly from the effects of the great sea-wave. In fact, on two
+occasions the whole town has been destroyed, and nearly all its
+inhabitants have been drowned, through the inrush of precisely such
+waves as flowed into the ports of Arica and Chala. But upon this
+occasion the centre of subterranean disturbance must have been so
+situated that either the wave was diverted from Callao, or, more
+probably, two waves reached Callao from different sources and at
+different times, so that the two undulations partly counteracted each
+other. Certain it is that, although the water retreated strangely from
+the coast near Callao, insomuch that a wide tract of the sea-bottom
+was uncovered, there was no inrushing wave comparable with those
+described above. The sea afterward rose and fell in an irregular
+manner, a circumstance confirming the supposition that the disturbance
+was caused by two distinct oscillations. Six hours after the
+occurrence of the earth-shock the double oscillations seemed for a
+while to have worked themselves into unison, for at this time three
+considerable waves rolled in upon the town. But clearly these waves
+must not be compared with those which in other instances had made
+their appearance within half an hour of the earth-throes. There is
+little reason to doubt that if the separate oscillations had
+re-enforced each other earlier, Callao would have been completely
+destroyed. As it was, a considerable amount of mischief was effected;
+but the motion of the sea presently became irregular again, and so
+continued until the morning of August 14th, when it began to ebb with
+some regularity. But during the 14th there were occasional renewals of
+the irregular motion, and several days elapsed before the regular ebb
+and flow of the sea were resumed.
+
+Such were among the phenomena presented in the region where the
+earthquake itself was felt. It will be seen at once that within this
+region, or rather along that portion of the sea-coast which falls
+within the central region of disturbance, the true character of the
+sea-wave generated by the earthquake could not be recognized. If a
+rock fall from a lofty cliff into a comparatively shallow sea, the
+water around the place where the rock has fallen is disturbed in an
+irregular manner. The sea seems at one place to leap up and down;
+elsewhere one wave seems to beat against another, and the sharpest eye
+can detect no law in the motion of the seething waters. But presently,
+outside the scene of disturbance, a circular wave is seen to form, and
+if the motion of this wave be watched it is seen to present the most
+striking contrast with the turmoil and confusion at its centre. It
+sweeps onward and outward in a regular undulation. Gradually it loses
+its circular figure (unless the sea-bottom happens to be unusually
+level), showing that although its motion is everywhere regular, it is
+not everywhere equally swift. A wave of this sort, though incomparably
+vaster, swept swiftly away on every side from the scene of the great
+earthquake near the Peruvian Andes. It has been calculated that the
+width of this wave varied from one million to five million feet, or,
+roughly, from two hundred to one thousand miles, while, when in
+mid-Pacific, the length of the wave, measured along its summit in a
+widely-curved path from one side to another of the great ocean,
+cannot have been less than eight thousand miles.
+
+[Illustration: OVER A LARGE PORTION OF ITS COURSE ITS PASSAGE WAS
+UNNOTED.]
+
+We cannot tell how deep-seated was the centre of subterranean action;
+but there can be no doubt it was very deep indeed, because otherwise
+the shock felt in towns separated from each other by hundreds of miles
+could not have been so nearly contemporaneous. Therefore the portion
+of the earth's crust upheaved must have been enormous, for the length
+of the region where the direct effects of the earthquake were
+perceived is estimated by Professor von Hochsteter at no less than
+two hundred and forty miles. The breadth of the region is unknown,
+because the slope of the Andes on one side and the ocean on the other
+concealed the motion of the earth's crust.
+
+The great ocean-wave swept, as we have said, in all directions around
+the scene of the earth-throe. Over a large part of its course its
+passage was unnoted, because in the open sea the effects even of so
+vast an undulation could not be perceived. A ship would slowly rise as
+the crest of the great wave passed under her, and then as slowly sink
+again. This may seem strange, at first sight, when it is remembered
+that in reality the great sea-wave we are considering swept at the
+rate of three or four hundred sea-miles an hour over the larger part
+of the Pacific. But when the true character of ocean-waves is
+understood, when it is remembered that there is no transference of the
+water itself at this enormous rate, but simply a transmission of
+motion (precisely as when in a high wind waves sweep rapidly over a
+cornfield, while yet each cornstalk remains fixed in the ground), it
+will be seen that the effects of the great sea-wave could only be
+perceived near the shore. Even there, as we shall presently see, there
+was much to convey the impression that the land itself was rising and
+falling rather than that the deep was moved. But among the hundreds of
+ships which were sailing upon the Pacific when its length and breadth
+were traversed by the great sea-wave, there was not one in which any
+unusual motion was perceived.
+
+In somewhat less than three hours after the occurrence of the
+earthquake the ocean-wave inundated the port of Coquimbo, on the
+Chilean seaboard, some eight hundred miles from Arica. An hour or so
+later it had reached Constitucion, four hundred and fifty miles
+farther south; and here for some three hours the sea rose and fell
+with strange violence. Farther south, along the shore of Chile, even
+to the island of Chiloe, the shore-wave travelled, though with
+continually diminishing force, owing, doubtless, to the resistance
+which the irregularities of the shore opposed to its progress.
+
+The northerly shore-wave seems to have been more considerable; and a
+moment's study of a chart of the two Americas will show that this
+circumstance is highly significant. When we remember that the
+principal effects of the land-shock were experienced within that angle
+which the Peruvian Andes form with the long north-and-south line of
+the Chilean and Bolivian Andes, we see at once that, had the centre of
+the subterranean action been near the scene where the most destructive
+effects were perceived, no sea-wave, or but a small one, could have
+been sent toward the shores of North America. The projecting shores of
+northern Peru and Ecuador could not have failed to divert the sea-wave
+toward the west; and though a reflected wave might have reached
+California, it would only have been after a considerable interval of
+time, and with dimensions much less than those of the sea-wave which
+travelled southward. When we see that, on the contrary, a wave of even
+greater proportions travelled toward the shores of North America, we
+seem forced to the conclusion that the centre of the subterranean
+action must have been so far to the west that the sea-wave generated
+by it had a free course to the shores of California.
+
+Be this as it may, there can be no doubt that the wave which swept the
+shores of Southern California, rising upward of sixty feet above the
+ordinary sea-level, was absolutely the most imposing of all the
+indirect effects of the great earthquake. When we consider that even
+in San Pedro Bay, fully five thousand miles from the centre of
+disturbance, a wave twice the height of an ordinary house rolled in
+with unspeakable violence only a few hours after the occurrence of the
+earth-throe, we are most strikingly impressed with the tremendous
+energy of the earth's movement.
+
+Turning to the open ocean, let us track the great wave on its course
+past the multitudinous islands which dot the surface of the Pacific.
+
+The inhabitants of the Sandwich Islands, which lie about six thousand
+three hundred miles from Arica, might have imagined themselves safe
+from any effects which could be produced by an earthquake taking place
+so far away from them. But on the night between August 13th and 14th,
+the sea around this island group rose in a surprising manner, insomuch
+that many thought the islands were sinking, and would shortly subside
+altogether beneath the waves. Some of the smaller islands, indeed,
+were for a time completely submerged. Before long, however, the sea
+fell again, and as it did so the observers "found it impossible to
+resist the impression that the islands were rising bodily out of the
+water." For no less than three days this strange oscillation of the
+sea continued to be experienced, the most remarkable ebbs and floods
+being noticed at Honolulu, on the island of Woahoo.
+
+But the sea-wave swept onward far beyond these islands.
+
+At Yokohama, in Japan, more than ten thousand five hundred miles from
+Arica, an enormous wave poured in on August 14th, but at what hour we
+have no satisfactory record. So far as distance is concerned, this
+wave affords most surprising evidence of the stupendous nature of the
+disturbance to which the waters of the Pacific Ocean had been
+subjected. The whole circumference of the earth is but twenty-five
+thousand miles, so that this wave had travelled over a distance
+considerably greater than two-fifths of the earth's circumference. A
+distance which the swiftest of our ships could not traverse in less
+than six or seven weeks had been swept over by this enormous
+undulation in the course of a few hours.
+
+More complete details reach us from the Southern Pacific.
+
+Shortly before midnight the Marquesas Isles and the low-lying Tuamotu
+group were visited by the great wave, and some of these islands were
+completely submerged by it. The lonely Opara Isle, where the steamers
+which run between Panama and New Zealand have their coaling station,
+was visited at about half-past eleven in the evening by a billow which
+swept away a portion of the coal depot. Afterward great waves came
+rolling in at intervals of about twenty minutes, and several days
+elapsed before the sea resumed its ordinary ebb and flow.
+
+It was not until about half-past two on the morning of August 14th
+that the Samoa Isles (sometimes called the Navigator Islands) were
+visited by the great wave. The watchmen startled the inhabitants from
+their sleep by the cry that the sea was about to overwhelm them; and
+already, when the terrified people rushed from their houses, the sea
+was found to have risen far above the highest water-mark. But it
+presently began to sink again, and then commenced a series of
+oscillations, which lasted for several days, and were of a very
+remarkable nature. Once in every quarter of an hour the sea rose and
+fell, but it was noticed that it rose twice as rapidly as it sank.
+This peculiarity is well worth remarking. The eminent physicist Mallet
+speaks thus (we follow Lyell's quotation) about the waves which
+traverse an open sea: "The great sea-wave, advancing at the rate of
+several miles in a minute, consists, in the deep ocean, of a long, low
+swell of enormous volume, having an equal slope before and behind, and
+that so gentle that it might pass under a ship without being noticed.
+But when it reaches the edge of soundings, its front slope becomes
+short and steep, while its rear slope is long and gentle." On the
+shores visited by such a wave, the sea would appear to rise more
+rapidly than it sank. We have seen that this happened on the shores of
+the Samoa group, and therefore the way in which the sea rose and fell
+on the days following the great earthquake gave significant evidence
+of the nature of the sea-bottom in the neighborhood of these islands.
+As the change of the great wave's figure could not have been quickly
+communicated, we may conclude with certainty that the Samoan Islands
+are the summits of lofty mountains, whose sloping sides extend far
+toward the east.
+
+This conclusion affords interesting evidence of the necessity of
+observing even the seemingly trifling details of important phenomena.
+
+The wave which visited the New Zealand Isles was altogether different
+in character, affording a noteworthy illustration of another remark of
+Mallet's. He says that where the sea-bottom slopes in such a way that
+there is water of some depth close inshore, the great wave may roll in
+and do little damage; and we have seen that so it happened in the case
+of the Samoan Islands. But he adds that, "where the shore is shelving
+there will be first a retreat of the water, and then the wave will
+break upon the beach and roll far in upon the land." This is precisely
+what happened when the great wave reached the eastern shores of New
+Zealand, which are known to shelve down to very shallow water,
+continuing far away to sea toward the east.
+
+At about half-past three on the morning of August 14th the water began
+to retreat in a singular manner from the port of Littleton, on the
+eastern shores of the southernmost of the New Zealand Islands. At
+length the whole port was left entirely dry, and so remained for about
+twenty minutes. Then the water was seen returning like a wall of foam
+ten or twelve feet in height, which rushed with a tremendous noise
+upon the port and town. Toward five o'clock the water again retired,
+very slowly as before, not reaching its lowest ebb until six. An hour
+later a second huge wave inundated the port. Four times the sea
+retired and returned with great power at intervals of about two hours.
+Afterward the oscillation of the water was less considerable, but it
+had not wholly ceased until August 17th, and only on the 18th did the
+regular ebb and flow of the tide recommence.
+
+Around the Samoa group the water rose and fell once in every fifteen
+minutes, while on the shores of New Zealand each oscillation lasted no
+less than two hours. Doubtless the different depths of water, the
+irregular conformation of the island groups, and other like
+circumstances, were principally concerned in producing these singular
+variations. Yet they do not seem fully sufficient to account for so
+wide a range of difference. Possibly a cause yet unnoticed may have
+had something to do with the peculiarity. In waves of such enormous
+extent it would be quite impossible to determine whether the course of
+the wave motion was directed full upon a line of shore or more or less
+obliquely. It is clear that in the former case the waves would seem to
+follow each other more swiftly than in the latter, even though there
+were no difference in their velocity.
+
+Far on beyond the shores of New Zealand the great wave coursed,
+reaching at length the coast of Australia. At dawn of August 14th
+Moreton Bay was visited by five well-marked waves. At Newcastle, on
+the Hunter River, the sea rose and fell several times in a remarkable
+manner, the oscillatory motion commencing at half-past six in the
+morning. But the most significant evidence of the extent to which the
+sea-wave travelled in this direction was afforded at Port Fairy,
+Belfast, South Victoria. Here the oscillation of the water was
+distinctly perceived at midday on August 14th; and yet, to reach this
+point, the sea-wave must not only have travelled on a circuitous
+course nearly equal in length to half the circumference of the earth,
+but must have passed through Bass's Straits, between Australia and Van
+Diemen's Land, and so have lost a considerable portion of its force
+and dimensions. When w£ remember that had not the effects of the
+earth-shock on the water been limited by the shores of South America,
+a wave of disturbance equal in extent to that which travelled westward
+would have swept toward the east, we see that the force of the shock
+was sufficient to have disturbed the waters of an ocean covering the
+whole surface of the earth. For the sea-waves which reached Yokohama
+in one direction and Port Fairy in another had each traversed a
+distance nearly equal to half the earth's circumference; so that if
+the surface of the earth were all sea, waves setting out in opposite
+directions from the centre of disturbance would have met each other at
+the antipodes of their starting-point.
+
+It is impossible to contemplate the effects which followed the great
+earthquake--the passage of a sea-wave of enormous volume over fully
+one third of the earth's surface, and the force with which, on the
+farthermost limits of its range, the wave rolled in upon shores more
+than ten thousand miles from its starting-place--without feeling that
+those geologists are right who deny that the subterranean forces of
+the earth are diminishing in intensity. It may be difficult, perhaps,
+to look on the effects which are ascribed to ancient earth-throes
+without imagining for a while that the power of modern earthquakes is
+altogether less. But when we consider fairly the share which time had
+in those ancient processes of change, when we see that while mountain
+ranges were being upheaved or valleys depressed to their present
+position, race after race, and type after type appeared on the earth,
+and lived out the long lives which belong to races and to types, we
+are recalled to the remembrance of the great work which the earth's
+subterranean forces are still engaged upon. Even now continents are
+being slowly depressed or upheaved; even now mountain ranges are being
+raised to a new level, tablelands are in process of formation, and
+great valleys are being gradually scooped out. It may need an
+occasional outburst, such as the earthquake of August, 1868, to remind
+us that great forces are at work beneath the earth's surface. But, in
+reality, the signs of change have long been noted. Old shore-lines
+shift their place, old soundings vary; the sea advances in one place
+and retires in another; on every side Nature's plastic hand is at work
+modelling and remodelling the earth, in order that it may always be a
+fit abode for those who are to dwell upon it.
+
+[Illustration]
+
+
+
+
+THE PHOSPHORESCENT SEA
+
+(FROM STUDIES OF ANIMATED NATURE.)
+
+BY W.S. DALLAS.
+
+
+[Illustration]
+
+It is not merely on land that this phenomenon of phosphorescence is to
+be seen in living forms. Among marine animals, indeed, it is a
+phenomenon much more general, much more splendid, and, we may add,
+much more familiar to those who live on our coasts. There must be many
+in the British Isles who have never had the opportunity of seeing the
+light of the glow-worm, but there can be few of those who have
+frequented in summer any part of our coasts, who have never seen that
+beautiful greenish light which is then so often visible, especially on
+our southern shores, when the water is disturbed by the blade of an
+oar or the prow of a boat or ship. In some cases, even on our own
+shores, the phenomenon is much more brilliant, every rippling wave
+being crested with a line of the same peculiar light, and in warmer
+seas exhibitions of this kind are much more common. It is now known
+that this light is due to a minute living form, to which we will
+afterward return.
+
+But before going on to speak in some detail of the organisms to which
+the phosphorescence of the sea is due, it will be as well to mention
+that the kind of phosphorescence just spoken of is only one mode in
+which the phenomenon is exhibited on the ocean. Though sometimes the
+light is shown in continuous lines whenever the surface is disturbed,
+at other times, and, according to M. de Quatrefages, more commonly,
+the light appears only in minute sparks, which, however numerous,
+never coalesce. "In the little channel known as the Sund de Chausez,"
+he writes, "I have seen on a dark night each stroke of the oar kindle,
+as it were, myriads of stars, and the wake of the craft appeared in a
+manner besprinkled with diamonds." When such is the case the
+phosphorescence is due to various minute animals, especially
+crustaceans; that is, creatures which, microscopically small as they
+are, are yet constructed more or less on the type of the lobster or
+cray-fish.
+
+At other times, again, the phosphorescence is still more partial.
+"Great domes of pale gold with long streamers," to use the eloquent
+words of Professor Martin Duncan, "move slowly along in endless
+succession; small silvery disks swim, now enlarging and now
+contracting, and here and there a green or bluish gleam marks the
+course of a tiny, but rapidly rising and sinking globe. Hour after
+hour the procession passes by, and the fishermen hauling in their nets
+from the midst drag out liquid light, and the soft sea jellies,
+crushed and torn piecemeal, shine in every clinging particle. The
+night grows dark, the wind rises and is cold, and the tide changes; so
+does the luminosity of the sea. The pale spectres below the surface
+sink deeper, and are lost to sight, but the increasing waves are
+tinged here and there with green and white, and often along a line,
+where the fresh water is mixing with the salt in an estuary, there is
+a brightness so intense that boats and shores are visible.... But if
+such sights are to be seen on the surface, what must not be the
+phosphorescence of the depths! Every sea-pen is glorious in its light,
+in fact, nearly every eight-armed Alcyonarian is thus resplendent, and
+the social Pyrosoma, bulky and a free swimmer, glows like a bar of hot
+metal with a white and green radiance."
+
+Such accounts are enough to indicate how varied and how general a
+phenomenon is the phosphorescence of the sea. To take notice of one
+tithe of the points of interest summed up in the paragraph just quoted
+would occupy many pages, and we must therefore confine the attention
+to a few of the most interesting facts relating to marine
+phosphorescence.
+
+We will return to that form of marine luminosity to which we first
+referred: what is known as the general or diffused phosphorescence of
+the sea. From this mode of describing it the reader must not infer
+that the surface of the ocean is ever to be seen all aglow in one
+sheet of continuous light. So far, at least, as was ever observed by
+M. de Quatrefages, who studied this phenomenon carefully and during
+long periods on the coasts of Brittany and elsewhere, no light was
+visible when the surface of the sea was perfectly still. On the other
+hand, when the sea exhibits in a high degree the phenomenon of
+diffused phosphorescence no disturbance can be too slight to cause the
+water to shine with that peculiar characteristic gleam. Drop but a
+grain of sand upon its surface, and you will see a point of light
+marking the spot where it falls, and from that point as a centre a
+number of increasing wavelets, each clearly defined by a line of
+light, will spread out in circles all around.
+
+The cause of this diffused phosphorescence was long the subject of
+curiosity, and was long unknown, but more than a hundred years ago (in
+1764) the light was stated by M. Kigaut to proceed from a minute and
+very lowly organism, now known as _Noctiluca miliaris_; and subsequent
+researches have confirmed this opinion. This Noctiluca is a spherical
+form of not more than one-fiftieth of an inch in size, with a slight
+depression or indentation at one point, marking the position of a
+mouth leading to a short digestive cavity, and having close beside it
+a filament, by means of which it probably moves about. The sphere is
+filled with protoplasm, in which there is a nucleus and one or more
+gaps, or "vacuoles." Such is nearly all the structure that can be
+discerned with the aid of the microscope in this simple organism.
+
+Nevertheless, this lowly form is the chief cause of that diffused
+phosphorescence which is sometimes seen over a wide extent of the
+ocean. How innumerable the individuals belonging to this species must
+therefore be, may be left to the imagination. Probably the Noctiluca
+is not rivalled in this respect even by miscroscopic unicellular algæ
+which compose the "red snow."
+
+By filtering sea-water containing Noctilucæ its light can be
+concentrated, and it has been found that a few teaspoonfuls will then
+yield light enough to enable one to read holding a book at the
+ordinary distance from the eyes--about ten inches.
+
+A singular and highly remarkable case of diffused marine
+phosphorescence was observed by Nordenskiöld during his voyage to
+Greenland in 1883. One dark night, when the weather was calm and the
+sea smooth, his vessel was steaming across a narrow inlet called the
+Igaliko Fjord, when the sea was suddenly observed to be illumined in
+the rear of the vessel by a broad but sharply-defined band of light,
+which had a uniform, somewhat golden sheen, quite unlike the ordinary
+bluish-green phosphorescence of the sea. The latter kind of light was
+distinctly visible at the same time in the wake of the vessel. Though
+the steamer was going at the rate of from five to six miles an hour,
+the remarkable sheet of light got nearer and nearer. When quite close,
+it appeared as if the vessel were sailing in a sea of fire or molten
+metal. In the course of an hour the light passed on ahead, and
+ultimately it disappeared in the remote horizon. The nature of this
+phenomenon Nordenskiöld is unable to explain; and unfortunately he had
+not the opportunity of examining it with the spectroscope.
+
+If we come now to consider the more partial phosphorescence of the
+sea, we find that it is due to animals belonging to almost every group
+of marine forms--to Echinoderms, or creatures of the sea-urchin and
+star-fish type, to Annelid worm, to Medusidæ, or jelly-fish, as they
+are popularly called, including the "great domes" and the "silvery
+disks" of the passage above quoted from Professor Martin Duncan, to
+Tunicates, among which is the Pyrosoma, to Mollusks, Crustaceans, and
+in very many cases to Actinozoa, or forms belonging to the type of the
+sea anemone and the coral polyp.
+
+Of these we will single out only a few for more special notice.
+
+Many of the Medusidæ, or jelly-fish, possess the character of which we
+are speaking. In some cases the phosphorescence is spontaneous among
+them, but in others it is not so; the creature requires to be
+irritated or stimulated in some way before it will emit the light. It
+is spontaneous, for example, in the _Pelagia phosphorea_, but not in
+the allied _Pelagia noctiluca_, a very common form in the
+Mediterranean.
+
+In both of the jelly-fishes just mentioned the phosphorescence, when
+displayed at all, is on the surface of the swimming disk, and this is
+most commonly the case with the whole group. Sometimes, however, the
+phosphorescence is specially localized. In some forms, as in
+_Thaumantius pilosella_ and other members of the same genus, it is
+seen in buds at the base of tentacles given off from the margin of the
+swimming-bell. In other cases it is situated in certain internal
+organs, as in the canals which radiate from the centre to the margin
+of the bell, or in the ovaries. It is from this latter seat that the
+phosphorescence proceeds in _Oceania pilata_, the form which gives out
+such a light that Ehrenberg compared it to a lamp-globe lighted by a
+flame.
+
+The property of emitting a phosphorescent light, sometimes
+spontaneously and sometimes on being stimulated, is likewise
+exemplified in the Ctenophora, a group resembling the Medusidge in
+the jelly-like character of their bodies, but more closely allied in
+structure to the Actinozoa. But we will pass over these cases in order
+to dwell more particularly on the remarkable tunicate known as
+Pyrosoma, a name indicative of its phosphorescent property, being
+derived from two Greek words signifying fire-body. As shown in the
+illustration Pyrosoma is not a single creature, but is composed of a
+whole colony of individuals, each of which is represented by one of
+the projections on the surface of the tube, closed at one end, which
+they all combine to form. The free end on the exterior contains the
+mouth, while there is another opening in each individual toward the
+interior of the tube. Such colonies, which swim about by the alternate
+contraction and dilatation of the individuals composing them, are
+pretty common in the Mediterranean, where they may attain the length
+of perhaps fourteen inches, with a breadth of about three inches. In
+the ocean they may reach a much greater size. Mr. Moseley, in his
+"Notes of a Naturalist on the Challenger," mentions a giant specimen
+which he once caught in the deep-sea trawl, a specimen four feet in
+length and ten inches in diameter, with "walls of jelly about an inch
+in thickness."
+
+[Illustration: A. PYROSOMA. B. PONITON. (Magnified.)]
+
+The same naturalist states that the light emitted by this compound
+form is the most beautiful of all kinds of phosphorescence. When
+stimulated by a touch, or shake, or swirl of the water, it "gives out
+a globe of bluish light, which lasts for several seconds, as the
+animal drifts past several feet beneath the surface, and then suddenly
+goes out." He adds that on the giant specimen just referred to be
+wrote his name with his finger as it lay on the deck in a tub at
+night, and in a few seconds he had the gratification of seeing his
+name come out in "letters of fire."
+
+Among mollusks, the best known instance of phosphorescence is in the
+rock-boring Pholas, the luminosity of which after death is mentioned
+by Pliny. But it is not merely after death that Pholas becomes
+luminous--a phenomenon perfectly familiar even in the case of many
+fish, especially the herring and mackerel. It was long before the
+luminosity of the living animal was known, but this is now a
+well-ascertained fact; and Panceri, an Italian naturalist, recently
+dead, has been able to discover in this, as in several other marine
+phosphorescent forms, the precise seat of the light-giving bodies,
+which he has dissected out again and again for the sake of making
+experiments in connection with this subject.
+
+A more beautiful example of a phosphorescent mollusk is presented by a
+sea-slug called _Phyllirhoë bucephala_. This is a creature of from one
+and a half to two inches in length, without a shell in the adult
+stage, and without even gills. It breathes only by the general surface
+of the body. It is common enough in the Mediterranean, but is not easy
+to see, as it is almost perfectly transparent, so that it cannot be
+distinguished without difficulty, by day at least, from the medium in
+which it swims. By night, however, it is more easily discerned, in
+consequence of its property of emitting light. When disturbed or
+stimulated in any way, it exhibits a number of luminous spots of
+different sizes irregularly distributed all over it, but most thickly
+aggregated on the upper and under parts. These phosphorescent spots,
+it is found, are not on the surface, but for the most part represent
+so many large cells which form the terminations of nerves, and are
+situated underneath the transparent cuticle. The spots shine with
+exceptional brilliancy when the animal is withdrawn from the water and
+stimulated by a drop of ammonia.
+
+Among the Annelid worms a species of _Nereis_, or sea-centipedes, has
+earned by its phosphorescent property the specific name of _noctiluca_
+(night-shining), and the same property is very beautifully shown in
+_Polynoë_, a near ally of the familiar sea-mouse. M. de Quatrefages
+speaks with enthusiasm of the beauty of the spectacle presented by
+this latter form when examined under a microscope magnifying to the
+extent of a hundred diameters. He then found, as he did in the great
+majority of cases which he studied, that the phosphorescence was
+confined to the motor muscles, and was manifested solely when these
+were in the act of contracting, manifested, too, not in continuous
+lines along the course of the muscles, but in rows of brilliant
+points.
+
+More interesting than the Annelids, however, are the Alcyonarian
+Actinozoa. The Actinozoa have already been described as formed on the
+type of the sea-anemone and the coral polyp, that is, they are all
+animals with a radiate structure, attached to one end, and having
+their only opening at the other end, which is surrounded by tentacles.
+In the Alcyonarian forms belonging to this great group these tentacles
+are always eight in number, and fringed on both sides. Moreover, these
+forms are almost without exception compound. Like the Pyrosoma, they
+have a common life belonging to a whole stock or colony, as well as an
+individual life.
+
+Now, throughout this sub-division of the Actinozoa phosphorescence is
+a very general phenomenon. Professor Moseley, already quoted as a
+naturalist accompanying the Challenger expedition, informs us that
+"all the Alcyonarians dredged by the Challenger in deep water were
+found to be brilliantly phosphorescent when brought to the surface."
+
+Among these Alcyonarians are the sea-pens mentioned in the quotation
+above made from Professor Martin Duncan. Each sea-pen is a colony of
+Alcyonarians, and the name is due to the singular arrangement of the
+individuals upon the common stem. This stem is supported internally by
+a coral rod, but its outer part is composed of fleshy matter belonging
+to the whole colony. The lower portion of it is fixed in the muddy
+bottom of the sea, but the upper portion is free, and gives off a
+number of branches, on which the individual polyps are seated. The
+whole colony thus has the appearance of a highly ornamental pen.
+
+There is one British species, _Pennatula phosphorea_, which is found
+in tolerably deep water, and is from two to four inches in length. The
+specific name again indicates the phosphorescent quality belonging to
+it. When irritated, it shines brilliantly, and the curious thing is
+that the phosphorescence travels gradually on from polyp to polyp,
+starting from the point at which the irritation is applied. If the
+lower part of the stem is irritated, the phosphorescence passes
+gradually upwards along each pair of branches in succession; but if
+the top is irritated the phosphorescence will pass in the same way
+downwards. When both top and bottom are irritated simultaneously two
+luminous currents start at once, and, meeting in the middle, usually
+become extinguished there; but on one occasion Panceri found that the
+two crossed, and each completed its course independently of the other.
+Those of our readers who have had opportunities of making or seeing
+experiments with the sensitive plant (_Mimosa pudica_) will be
+reminded of the way in which, when that plant is irritated, the
+influence travels regularly on from pinnules to pinnules and pinnae to
+pinnae.
+
+In all the cases mentioned the phenomenon of phosphorescence is
+exhibited by invertebrate animals; but though rare, it is not an
+unknown phenomenon even in living vertebrates. In a genus of deep-sea
+fishes called Stomias, Gunther mentions that a "series of
+phosphorescent dots run along the lower side of the head, body, and
+tail." Several other deep-sea fishes, locally phosphorescent, seem to
+have been dredged up by the French ship Talisman in its exploring
+cruise off the west coast of Northern Africa in 1883. During the same
+expedition, a number of deep-sea phosphorescent crustaceans were
+dredged up, the phosphorescence being in some cases diffused over the
+whole body, in other cases localized to particular areas. In deep-sea
+forms the phenomenon is, in fact, so common, as to have given rise to
+the theory that in the depths of the ocean, where the light of the
+sun cannot penetrate, the phosphorescence of various organisms diffuse
+a light which limits the domain of absolute darkness.
+
+So much by way of illustration regarding the phosphorescence exhibited
+by animals, terrestrial and marine; but it ought to be noticed that
+there are also a few cases in which the same phenomenon is to be
+witnessed in plants. These are not so numerous as was at one time
+supposed, the property having been mistakenly ascribed to some plants
+not really luminous.
+
+[Illustration: A PHOSPHORESCENT SEA.]
+
+In some instances the mistake appears to have been due to a subjective
+effect produced by brilliantly colored (red or orange) flowers, such
+as the great Indian cress, the orange lily, the sunflower, and the
+marigold. The fact that such flowers do give out in the dusk sudden
+flashes of light has often been stated on the authority of a daughter
+of Linnæus, subsequently backed by the assertions of various other
+observers. But most careful observers seem to be agreed that the
+supposed flashes of light are in reality nothing else than a certain
+dazzling of the eyes.
+
+In another case, in which a moss, _Schistostega osmundacea_, has been
+stated to be phosphorescent, the effect is said to be really due to
+the refraction and reflection of light by minute crystals scattered
+over its highly cellular leaves, and not to be produced at all where
+the darkness is complete.
+
+Among plants, genuine phosphorescence is to be found chiefly in
+certain fungi, the most remarkable of which is _Rhizomorpha
+subterranea_, which is sometimes to be seen ramifying over the walls
+of dark, damp mines, caverns, or decayed towers, and emitting at
+numerous points a mild phosphorescent light, which is sometimes bright
+enough to allow of surrounding objects being distinguished by it. The
+name of "vegetable glow-worm" has sometimes been applied to this
+curious growth.
+
+Among other phosphorescent fungi are several species of Agaricus,
+including the _A. olearius_ of Europe, _A. Gardneri_ of Brazil, and
+_A. lampas_ of Australia, and besides the members of this genus,
+_Thelaphora cærulea_, which is the cause of the phosphorescent light
+sometimes to be seen on decaying wood--the "touchwood" which many boys
+have kept in the hope of seeing this light displayed. The milky juice
+of a South American Euphorbia (_E. phosphorea_) is stated by Martins
+to be phosphorescent when gently heated. But phosphorescence is
+evidently not so interesting and important a phenomenon in the
+vegetable as it is in the animal kingdom.
+
+The whole phenomenon is one that gives rise to a good many questions
+which it is not easy to answer, and this is especially true in the
+case of animal phosphorescence. What is the nature of the light? What
+are the conditions under which it is manifested? What purpose does it
+serve in the animal economy?
+
+As to the nature of the light, the principal question is whether it is
+a direct consequence of the vital activity of the organism in which it
+is seen, of such a nature that no further explanation can be given of
+it, any more than we can explain why a muscle is contracted under the
+influence of a nerve-stimulus; or whether it is due to some chemical
+process more or less analogous to the burning of a candle.
+
+The fact of luminosity appearing to be in certain cases directly under
+the control of the creature in which it is found, and the fact of its
+being manifested in many forms, as M. de Quatrefages found, only when
+muscular contraction was taking place, would seem to favor the former
+view. On the other hand, it is against this view that the
+phosphorescence is often found to persist after the animal is dead,
+and even in the phosphorescent organs for a considerable time after
+they have been extracted from the body of the animal. In the glow-worm
+the light goes on shining for some time after the death of the insect,
+and even when it has become completely extinguished it can be restored
+for a time by the application of a little moisture. Further, both
+Matteucci and Phipson found that when the luminous substance was
+extracted from the insect it would keep on glowing for thirty or forty
+minutes.
+
+In Pholas the light is still more persistent, and it is found that
+when the dead body of this mollusk is placed in honey, it will retain
+for more than a year the power of emitting light when plunged in warm
+water.
+
+The investigations of recent years have rendered it more and more
+probable that the light exhibited by phosphorescent organisms is due
+to a chemical process somewhat analogous to that which goes on in the
+burning of a candle. This latter process is one of rapid oxidation.
+The particles of carbon supplied by the oily matter that feeds the
+candle become so rapidly combined with oxygen derived from the air
+that a considerable amount of light, along with heat, is produced
+thereby. Now, the phenomenon of phosphorescence in organic forms,
+whether living or dead, appears also to be due to a process of
+oxidation, but one that goes on much more slowly than in the case of a
+lighted candle. It is thus more closely analogous to what is observed
+in the element phosphorus itself, which owes its name (meaning
+"light-bearer") to the fact that when exposed to the air at ordinary
+temperatures it glows in the dark, in consequence of its becoming
+slowly combined with oxygen.
+
+At one time it was believed that the presence of oxygen was not
+necessary to the exhibition of phosphorescence in organic forms, but
+it has now been placed beyond doubt that this is a mistake. Oxygen has
+been proved to be indispensable, and hence we see a reason for the
+luminous organs in the glow-worm being so intimately connected, as
+above mentioned, with the air-tubes that ramify through the insect.
+
+This fact of itself might be taken as a strong indication of the
+chemical nature of the process to which phosphorescence is due. But
+the problem has been made the subject of further investigations which
+have thrown more light upon it. It was long known that there were
+various inorganic bodies besides phosphorus which emitted a
+phosphorescent light in the dark, at least after being exposed to the
+rays of the sun; but it was not till quite recently that any organic
+compound was known to phosphoresce at ordinary temperatures.
+
+This discovery was made by a Polish chemist, named Bronislaus
+Radziszewski, who followed it up with a long series of experiments on
+the phosphorescence of organic compounds, by which he was able to
+determine the conditions under which that phenomenon was exhibited. In
+all the substances investigated by him in which phosphorescence was
+introduced he found that three conditions were essential to its
+production: (1) that oxygen should be present; (2) that there should
+be an alkaline reaction in the phosphorescing mixture--that is, a
+reaction such as is produced on acids and vegetable coloring matters
+by potash, soda, and the other alkalies; and (3) that some kind of
+chemical action should take place.
+
+He found, moreover, that among the organic compounds that could be
+made to phosphoresce under these conditions were nearly all the fixed
+and ethereal oils. With reference to the phosphorescence of animals,
+this observation is important, for it has been shown in a great many
+cases that a fatty substance forms the main constituent in their
+luminous organs. This has long been known to be the case in the
+luminous insects belonging to the Lampyridæ and Elateridæ, as well as
+in the luminous centipedes; and the researches of Panceri, already
+referred to, on the luminous organs of many marine forms have shown
+that it holds good with regard to these also.
+
+We may, therefore, conclude that substances fitted to phosphoresce
+under the conditions determined by the experiments of Radziszewski are
+generally, and probably universally, present in the luminous organs of
+phosphorescent animals. Now, what is to be said as to the occurrence
+of these conditions? The access of oxygen is in all cases easy to
+account for, but it must also be shown how the alkaline reaction is to
+be produced. We need not expect to find in animal organisms potash,
+soda, ammonia, and the other common alkalies; but it was established
+by experiment that the alkaline organic compounds cholin and neurin,
+which are present in animal tissues, would also serve to bring about
+the phenomenon of phosphorescence in the substances on which the
+experiments were made.
+
+Accordingly, it seems fair to conclude that when all these conditions
+for the production of phosphorescence in a chemical laboratory are
+present in animal organisms, the phenomenon, when observed in these,
+is exactly of the same nature as that which is produced artificially.
+By that it is meant that animal phosphorescence is attended, like the
+artificial phenomenon, by a slow chemical action, or in other words,
+that the phosphorescent light is due to a gradual process of
+oxidation.
+
+One curious circumstance has been discovered which lends still further
+probability to this explanation. It was mentioned above that among
+phosphorescent plants there are several species of Agaricus. Now,
+from one species of this genus, though not indeed one of the
+phosphorescent species (from _A. muscarius_) there has been extracted
+a principle called _amanitia_, which is found to be identical with
+cholin. In the light of the results derived from the investigations
+just referred to it is reasonable to draw the conclusion that, if
+sought for, this principle would likewise be found in the
+phosphorescent species in which the other conditions of
+phosphorescence are also present.
+
+On this theory of the production of the phenomenon now under
+consideration, the effect of shaking or of vital action in giving rise
+to or intensifying the exhibition of the light is accounted for by the
+fact that by these means fresh supplies of oxygen are brought into
+contact with the phosphorescent substance. The effect of ammonia on
+the light emitted by the sea-slug _Phyllirhoë bucephala_, is also
+fully explained, ammonia being one of those alkaline substances which
+are so directly favorable to the exhibition of the phenomenon.
+
+Nor is it difficult to account for the control which in some cases
+insects appear to have over the luminosity of the phosphorescent
+organs, exhibiting and withdrawing the light at will. It is not
+necessary to suppose that this is an immediate effect, a conversion of
+nerve force into light, and a withdrawal of that force. The action of
+the creature's will may be merely in maintaining or destroying the
+conditions under which the light is manifested. It may, for example,
+have the power of withdrawing the supply of oxygen, and this
+supposition receives some countenance from the observation cited from
+Kirby and Spence on the two captured glow-worms, one of which
+withdrew its light, while the other kept it shining, but while doing
+so had the posterior extremity of the abdomen in constant motion. But
+the animal may also have the power in another way of affecting the
+chemical conditions of the phenomenon. It may, for example, have the
+power of increasing or diminishing by some nervous influence the
+supply of the necessary alkaline ingredient.
+
+But if animal phosphorescence is really due to a process of slow
+oxidation, there is one singular circumstance to be noted in
+connection with it. Oxidation is a process that is normally
+accompanied by the development of heat. Even where no light is
+produced an increase of temperature regularly takes place when
+substances are oxidized. We ought, then, to expect such a rise of
+temperature when light is emitted by the phosphorescent organs of
+animals. But the most careful observations have shown that nothing of
+the kind can be detected. It was with a view to test this that Panceri
+dissected out the luminous organs of so many specimens of Pholas. He
+selected this mollusk because it was so abundant in the neighborhood
+of Naples, where, his experiments were made; and in making his
+experiments he made use of a thermopile, an apparatus by which, with
+the aid of electricity, much smaller quantities of heat can be
+indicated than by means of the most delicate thermometer. The organs
+remained luminous long after they were extracted, but no rise in
+temperature whatever could be found to accompany the luminosity. Many
+experiments upon different animals were made with similar negative
+results by means of the thermometer.
+
+The only explanation of this that can be given is probably to be found
+in the fact that the chemical process ascertained to go on in the
+phosphorescence of organic compounds on which experiments were made in
+the laboratory is an extremely slow one.
+
+The so-called phosphorescence of most inorganic bodies is one of a
+totally different nature from that exhibited in organic forms. The
+diamond shines for a time in the dark after it has been exposed to the
+sun; so do pieces of quartz when rubbed together, and powdered
+fluor-spar when heated shines with considerable brilliancy. Various
+artificial compounds, such as sulphide of calcium (Canton's
+phosphorus, as it is called from the discoverer), sulphate of barium
+(Bologna stone, or Bologna phosphorus), sulphide of strontium, etc.,
+after being illuminated by the rays of the sun, give out in the dark a
+beautiful phosphorescence, green, blue, violet, orange, red, according
+to circumstances. The luminous paint which has recently attracted so
+much attention is of the same nature. In these cases what we have is
+either a conversion of heat rays into light rays (as in the powdered
+fluor-spar), or the absorption and giving out again of sun-rays. In
+the latter case the phenomenon is essentially the same as
+fluorescence, in which the dark rays of the solar spectrum beyond the
+violet are made visible.
+
+But we must now return to the other questions that have been started
+in relation to phosphorescence in animals. There has been much
+speculation as to the object of this light, and to the purposes it
+serves in Nature. Probably no general answer can be given to this
+question. It is no doubt impossible to show why so many animals have
+been endowed with this remarkable property; but we may consider some
+of the effects which the possession of it has in different cases.
+
+In the first place, it will undoubtedly serve in many cases to afford
+light to enable the animal to see by, and in the Lampyridæ it would
+seem that the degree of luminosity is related to the development of
+the vision. In that family, according to the Rev. H.S. Gorham, the
+eyes are developed, as a rule, in inverse proportion to the
+luminosity. Where there is an ample supply of this kind of light the
+eyes are small, but where the light is insignificant the eyes are
+large by way of compensation. And moreover, where both eyes and light
+are small, then the antennae are large and feathery, so that the
+deficiency in the sense of sight is made up for by an unusual
+development in the organs of touch.
+
+But it is none the less certain that the presence of this light cannot
+always be designed to serve this purpose, for many of the animals so
+endowed are blind. The phosphorescent centipedes are without eyes,
+like all the other members of the genus (_Geophilus_) to which they
+belong, and probably the majority of phosphorescent marine forms are
+likewise destitute of organs of sight.
+
+Another suggestion is that the light derived from these marine forms,
+and especially from deep-sea Alcyonarians, is what enables the members
+of the deep-sea fauna that are possessed of eyes (which are always
+enormously enlarged) to see. Such is the suggestion of Dr. Carpenter,
+Sir Wyville Thomson, and Mr. Gwyn Jeffries; and it is possible that
+this actually is one of the effects of the phosphorescent property.
+But if so, it remains to inquire how the forms endowed with it came
+to be possessed of a power useful in that way to other forms, but not
+to themselves. According to the Darwinian doctrine of development, the
+powers that are developed in different organisms by the process of
+natural selection are such as are useful to themselves and not to
+others, unless incidentally.
+
+This consideration has led to another suggestion, namely, that the
+property of phosphorescence serves as a protection to the forms
+possessing it, driving away enemies in one way or another: it may be
+by warning them of the fact that they are unpalatable food, as is
+believed to be the case with the colors of certain brilliantly-colored
+caterpillars; it may be in other ways. In Kirby and Spence one case is
+recorded in which the phosphorescence of the common phosphorescent
+centipede (_Geophilus electricus_) was actually seen apparently to
+serve as a means of defence against an enemy. "Mr. Shepherd," says
+that authority, "once noticed a scarabeus running round the
+last-mentioned insect when shining, as if wishing, but afraid to
+attack it." In the case of the jelly-fishes, it has been pointed out
+that their well-known urticating or stinging powers would make them at
+least unpleasant, if not dangerous, food for fishes; and that
+consequently the luminosity by which so many of them are characterized
+at night may serve at once as a warning to predatory fishes and as a
+protection to themselves. The experience of the unpleasant properties
+of many phosphorescent animals may likewise have taught fishes to
+avoid all forms possessing this attribute, even though many of them
+might be quite harmless.
+
+Lastly, it has been suggested that the phosphorescence in the female
+glow-worm may be designed to attract the male; and that it will
+actually have this effect may readily be taken for granted.
+Observation shows that the male glow-worm is very apt to be attracted
+by a light. Gilbert White of Selborne mentions that they, attracted by
+the light of the candles, came into his parlor. Another observer
+states that by the same light he captured as many as forty male
+glow-worms in one night.
+
+[Illustration]
+
+
+
+
+COMETS
+
+(FROM MARVELS OF THE HEAVENS.)
+
+BY CAMILLE FLAMMARION.
+
+
+  "Je viens vous annoncer une grande nouvelle:
+  Nous l'avons, en dormant, madame, échappé belle.
+  Un monde près de nous a passé tout du long,
+  Est chu tout au travers de notre tourbillon;
+  Et s'il eût en chemin rencontré notre terre,
+  Elle eût été brisée en morceaux comme verre."
+                                           MOLIÈRE.
+
+[Illustration]
+
+This announcement of Trissontin's to Philaminte, who begins the parody
+on the fears caused by the appearance of comets, would not have been a
+parody four or five centuries ago. These tailed bodies, which suddenly
+come to light up the heavens, were for long regarded with terror, like
+so many warning signs of divine wrath. Men have always thought
+themselves much more important than they really are in the universal
+order; they have had the vanity to pretend that the whole creation was
+made for them, whilst in reality the whole creation does not suspect
+their existence. The Earth we inhabit is only one of the smallest
+worlds; and therefore it can scarcely be for it alone that all the
+wonders of the heavens, of which the immense majority remains hidden
+from it, were created. In this disposition of man to see in himself
+the centre and the end of everything, it was easy indeed to consider
+the steps of nature as unfolded in his favor; and if some unusual
+phenomenon presented itself, it was considered to be without doubt a
+warning from Heaven. If these illusions had had no other result than
+the amelioration of the more timorous of the community one would
+regret these ages of ignorance; but not only were these fancied
+warnings of no use, seeing that once the danger passed, man returned
+to his former state; but they also kept up among people imaginary
+terrors, and revived the fatal resolutions caused by the fear of the
+end of the world.
+
+When one fancies the world is about to end,--and this has been
+believed for more than a thousand years,--no solicitude is felt in the
+work of improving this world; and, by the indifference or disdain into
+which one falls, periods of famine and general misery are induced
+which at certain times have overtaken our community. Why use the
+wealth of a world which is going to perish? Why work, be instructed,
+or rise in the progress of the sciences or arts? Much better to forget
+the world, and absorb one's self in the barren contemplation of an
+unknown life. It is thus that ages of ignorance weigh on man, and
+thrust him further and further into darkness, while Science makes
+known by its influence on the whole community, its great value, and
+the magnitude of its aim.
+
+The history of a comet would be an instructive episode of the great
+history of the heavens. In it could be brought together the
+description of the progressive movement of human thought, as well as
+the astronomical theory of these extraordinary bodies. Let us take,
+for example, one of the most memorable and best-known comets, and give
+an outline of its successive passages near the Earth. Like the
+planetary worlds, Comets belong to the solar system, and are subject
+to the rule of the Star King. It is the universal law of gravitation
+which guides their path; solar attraction governs them, as it governs
+the movement of the planets and the small satellites. The chief point
+of difference between them and the planets is, that their orbits are
+very elongated; and, instead of being nearly circular, they take the
+elliptical form. In consequence of the nature of these orbits, the
+same comet may approach very near the Sun, and afterwards travel from
+it to immense distances. Thus, the period of the Comet of 1680 has
+been estimated at three thousand years. It approaches the Sun, so as
+to be nearer to it than our Moon is to us, whilst it recedes to a
+distance 853 times greater than the distance of the Earth from the
+Sun. On the 17th of December, 1680, it was at its perihelion--that is,
+at its greatest proximity to the Sun; it is now continuing its path
+beyond the Neptunian orbit. Its velocity varies according to its
+distance from the solar body. At its perihelion it travels thousands
+of leagues per minute; at its aphelion it does not pass over more than
+a few yards. Its proximity to the Sun in its passage near that body
+caused Newton to think that it received a heat twenty-eight thousand
+times greater than that we experience at the summer solstice; and
+that this heat being two thousand times greater than that of red-hot
+iron, an iron globe of the same dimensions would be fifty thousand
+years entirely losing its heat. Newton added that in the end comets
+will approach so near the Sun that they will not be able to escape the
+preponderance of its attraction, and that they will fall one after the
+other into this brilliant body, thus keeping up the heat which it
+perpetually pours out into space. Such is the deplorable end assigned
+to comets by the author of the "Principia," an end which makes De la
+Brétonne say to Rétif: "An immense comet, already larger than Jupiter,
+was again increased in its path by being blended with six other dying
+comets. Thus displaced from its ordinary route by these slight shocks,
+it did not pursue its true elliptical orbit; so that the unfortunate
+thing was precipitated into the devouring centre of the Sun." "It is
+said," added he, "that the poor comet, thus burned alive, sent forth
+dreadful cries!"
+
+[Illustration: A COMET]
+
+It will be interesting, then, in a double point of view, to follow a
+comet in its different passages in sight of the Earth. Let us take the
+most important in astronomical history--the one whose orbit has been
+calculated by Edmund Halley, and which was named after him. It was in
+1682 that this comet appeared in its greatest brilliancy, accompanied
+with a tail which did not measure less than thirty-two millions of
+miles. By the observation of the path which it described in the
+heavens, and the time it occupied in describing it, this astronomer
+calculated its orbit, and recognized that the comet was the same as
+that which was admired in 1531 and 1607, and which ought to have
+reappeared in 1759. Never did scientific prediction excite a more
+lively interest. The comet returned at the appointed time; and on the
+12th of March, 1759, reached its perihelion. Since the year 12 before
+the Christian era, it had presented itself twenty-four times to the
+Earth. It was principally from the astronomical annals of China that
+it was possible to follow it up to this period.
+
+Its first memorable appearance in the history of France is that of
+837, in the reign of Louis le Débonnaire. An anonymous writer of
+chronicles of that time, named "The Astronomer," gave the following
+details of this appearance, relative to the influence of the comet on
+the imperial imagination:
+
+"During the holy days of the solemnization of Easter, a phenomenon
+ever fatal, and of gloomy foreboding, appeared in the heavens. As soon
+as the Emperor, who paid attention to these phenomena, received the
+first announcement of it, he gave himself no rest until he had called
+a certain learned man and myself before him. As soon as I arrived, he
+anxiously asked me what I thought of such a sign; I asked time of him,
+in order to consider the aspects of the stars, and to discover the
+truth by their means, promising to acquaint him on the morrow; but the
+Emperor, persuaded that I wished to gain time, which was true, in
+order not to be obliged to announce anything fatal to him, said to me:
+'Go on the terrace of the palace and return at once to tell me what
+you have seen, for I did not see this star last evening, and you did
+not point it out to me; but I know that it is a comet; tell me what
+you think it announces to me.' Then scarcely allowing me time to say
+a word, he added: 'There is still another thing you keep back; it is
+that a change of reign and the death of a prince are announced by this
+sign.' And as I advanced the testimony of the prophet, who said: 'Fear
+not the signs of the heavens as the nations fear them,' the prince
+with his grand nature, and the wisdom which never forsook him, said,
+'We must not only fear Him who has created both us and this star. But
+as this phenomenon may refer to us, let us acknowledge it as a warning
+from Heaven."
+
+Louis le Débonnaire gave himself and his court to fasting and prayer,
+and built churches and monasteries. He died three years later, in 840,
+and historians have profited by this slight coincidence to prove that
+the appearance of the comet was a harbinger of death. The historian,
+Raoul Glader, added later: "These phenomena of the universe are never
+presented to man without surely announcing some wonderful and terrible
+event."
+
+Halley's comet again appeared in April, 1066, at the moment when
+William the Conqueror invaded England. It was pretended that it had
+the greatest influence on the fate of the battle of Hastings, which
+delivered over the country to the Normans.
+
+A contemporary poet, alluding probably to the English diadem with
+which William was crowned, had proclaimed in one place, "that the
+comet had been more favorable to William than nature had been to
+Caesar; the latter had no hair, but William had received some from the
+comet." A monk of Malmesbury apostrophized the comet in these terms:
+"Here thou art again, thou cause of the tears of many mothers! It is
+long since I have seen thee, but I see thee now, more terrible than
+ever; thou threatenest my country with complete ruin!"
+
+In 1455, the same comet made a more memorable appearance still. The
+Turks and Christians were at war, the West and the East seemed armed
+from head to foot--on the point of annihilating each other. The
+crusade undertaken by Pope Calixtus III. against the invading
+Saracens, was waged with redoubled ardor on the sudden appearance of
+the star with the flaming tail. Mahomet II. took Constantinople by
+storm, and raised the siege of Belgrade. But the Pope having put aside
+both the curse of the comet, and the abominable designs of the
+Mussulmans, the Christians gained the battle, and vanquished their
+enemies in a bloody fight. The _Angelus_ to the sound of bells dates
+from these ordinances of Calixtus III. referring to the comet.
+
+In his poem on astronomy, Daru, of the French Academy, describes this
+episode in eloquent terms:
+
+  "Un autre Mahomet a-t-il d'un bras puissant
+  Aux murs de Constantine arboré le croissant:
+  Le Danube étonné se trouble au bruit des armes,
+  La Grèce est dans les fers, l'Europe est en alarmes;
+  Et pour comble d'horreur, l'astre au visage ardent
+  De ses ailes de feu va couvrir l'Occident.
+  Au pied de ses autels, qu'il ne saurait défendre,
+  Calixte, l'oeil en pleurs, le front convert de cendre,
+  Conjure la comète, objet de tant d'effroi:
+  Regarde vers les cieux, pontife, et lève-toi!
+  L'astre poursuit sa course, et le fer d'Huniade
+  Arrête le vainqueur, qui tombe sous Belgrade.
+  Dans les cieux cependant le globe suspendu,
+  Par la loi générale à jamais retenu,
+  Ignore les terreurs, l'existence de Rome,
+  Et la Terre peut-être, et jusqu'au nom de l'homme,
+  De l'homme, être crédule, atome ambitieux,
+  Qui tremble sous un prêtre et qui lit dans les cieux."
+
+This ancient comet witnessed many revolutions in human history, at
+each of its appearances, even in its later ones, in 1682, 1759, 1835;
+it was also presented to the Earth under the most diverse aspects,
+passing through a great variety of forms, from the appearance of a
+curved sabre, as in 1456, to that of a misty head, as in its last
+visit. Moreover, this is not an exception to the general rule, for
+these mysterious stars have had the gift of exercising a power on the
+imagination which plunged it in ecstasy or trouble. Swords of fire,
+bloody crosses, flaming daggers, spears, dragons, fish, and other
+appearances of the same kind, were given to them in the middle ages
+and the Renaissance.
+
+Comets like those of 1577 appear, moreover, to justify by their
+strange form the titles with which they are generally greeted. The
+most serious writers were not free from this terror. Thus, in a
+chapter on celestial monsters, the celebrated surgeon, Ambroise Paré,
+described the comet of 1528 under the most vivid and frightful colors:
+"This comet was so horrible and dreadful that it engendered such great
+terror to the people, that they died, some with fear, others with
+illness. It appeared to be of immense length, and of blood color; at
+its head was seen the figure of a curved arm, holding a large sword in
+the hand as if it wished to strike. At the point of the sword there
+were three stars, and on either side was seen a great number of
+hatchets, knives, and swords covered with blood, amongst which were
+numerous hideous human faces, with bristling beards and hair."
+
+The imagination has good eyes when it exerts itself. The great and
+strange variety of cometary aspects is described with exactitude by
+Father Souciet in his Latin poem on comets. "Most of them," says he,
+"shine with fires interlaced like thick hair, and from this they have
+taken the name of comets. One draws after it the twisted folds of a
+long tail; another appears to have a white and bushy beard; this one
+throws a glimmer similar to that of a lamp burning during the night;
+that one, O Titan! represents thy resplendent face; and this other, O
+Phoebe! the form of thy nascent horns. There are some which bristle
+with twisted serpents. Shall I speak of those armies which have
+sometimes appeared in the air? of those clouds which follow as it were
+along a circle, or which resemble the head of Medusa? Have there not
+often been seen figures of men or savage animals?
+
+"Often, in the gloom of night, lighted up by these sad fires, the
+horrible sound of arms is heard, the clashing of swords which meet in
+the clouds, the ether furiously resounding with fearful din which
+crush the people with terror. All comets have a melancholy light, but
+they have not all the same color. Some have a leaden color; others
+that of flame or brass. The fires of some have the redness of blood;
+others resemble the brightness of silver. Some again are azure; others
+have the dark and pale color of iron. These differences come from the
+diversity of the vapors which surround them, or from the different
+manner in which they receive the Sun's rays. Do you not see in our
+fires, that various kinds of wood produce different colors? Pines and
+firs give a flame mixed with thick smoke, and throw out little light.
+That which rises from sulphur and thick bitumen is bluish. Lighted
+straw gives out sparks of a reddish color. The large olive, laurel,
+ash of Parnassus, etc., trees which always retain their sap, throw a
+whitish light similar to that of a lamp. Thus, comets whose fires are
+formed of different materials, each take and preserve a color which is
+peculiar to them."
+
+Instead of being a cause of fear and terror, the variety and
+variability of the aspect of comets ought rather to indicate to us the
+harmlessness of their nature.
+
+[Illustration]
+
+
+
+
+THE TOTAL SOLAR ECLIPSE OF 1883
+
+_AN ASTRONOMERS VOYAGE TO FAIRY-LAND._
+
+(FROM THE ATLANTIC MONTHLY, MAY, 1890.)
+
+BY PROF. E.S. HOLDEN.
+
+
+[Illustration]
+
+In 1883 calculations showed that a solar eclipse of unusually long
+duration (5 minutes, 20 seconds) would occur in the South Pacific
+Ocean. The track of the eclipse lay south of the equator, but north of
+Tahiti. There were in fact only two dots of coral islands on the
+charts in the line of totality, Caroline Island, and one hundred and
+fifty miles west Flint Island (longitude 150 west, latitude 10 south).
+Almost nothing was known of either of these minute points. The station
+of the party under my charge (sent out by the United States government
+under the direction of the National Academy of Sciences) was to be
+Caroline Islands.
+
+Every inch of that island (seven miles long, a mile or so broad) is
+familiar now; but it is almost ludicrous to recollect with what
+anxiety we pored over the hydrographic charts and sailing instructions
+of the various nations, to find some information, however scanty,
+about the spot which was to be our home for nearly a month. All that
+was known was that this island had formerly been occupied as a guano
+station. There was a landing _then_.
+
+After the _personnel_ of the party had been decided on, there were the
+preparations for its subsistence to be looked out for. How to feed
+seventeen men for twenty-one days? Fortunately the provisions that we
+took, and the fresh fish caught for us by the natives, just sufficed
+to carry us through with comfort and with health.
+
+In March of 1883 we sailed from New York, and about the same time a
+French expedition left Europe bound for the same spot. From New York
+to Panama, from Panama to Lima, were our first steps. Here we joined
+the United States steamship Hartford, Admiral Farragut's flagship, and
+the next day set sail for our destined port,--if a coral reef
+surrounded by a raging surf can be called a port. About the same time
+a party of French observers under Monsieur Janssen, of the Paris
+Academy of Sciences, left Panama in the _Eclaireur_.
+
+[Illustration: BIRD'S EYE VIEW OF THE CAROLINE ISLANDS.]
+
+It was an ocean race of four thousand miles due west. The station
+Caroline Islands was supposed to be more desirable than Flint Island.
+Admiral Wilkes's expedition had lain off the latter several days
+without being able to land on account of the tremendous surf, so that
+it was eminently desirable to "beat the Frenchman," as the sailors put
+it. With this end in view our party had secured (through a member of
+the National Academy in Washington) the verbal promise of the proper
+official of the Navy Department that the Hartford's orders should read
+"to burn coal as necessary." The last obstacle to success was thus
+removed. We were all prepared, and now the ship would take us speedily
+to our station.
+
+Imagine our feelings the next day after leaving Callao, when the
+commanding officer of the Hartford opened his sealed orders. They read
+(dated Washington, in February), "To arrive at Caroline Islands (in
+April) with full coal-bunkers!"
+
+Officialism could go no further. Here was an expedition sent on a
+slow-sailing ship directly through the regions of calms for four
+thousand miles. It was of no possible use to send the expedition at
+all unless it arrived in time. And here were our orders "to arrive
+with full coal-bunkers."
+
+Fortunately we had unheard-of good-luck. The trade-wind blew for us as
+it did for the Ancient Mariner, and we sped along the parallel of 12°
+south at the rate of one hundred and fifty miles a day under sail,
+while the _Eclaireur_ was steaming for thirty days a little nearer the
+equator in a dead calm. We arrived off the island just in time, with
+not a day to spare. It was a narrow escape, and a warning to all of us
+never to sail again under sealed orders unless we knew what was under
+the seal.
+
+Here we were, then, lying off the island and scanning its sparse crown
+of cocoanut palms, looking for a French flag among their wavy tufts.
+There was none in sight. We were the winners in the long race.
+Directly a whale-boat was lowered, and rowed around the white fringe
+of tremendous surf that broke ceaselessly against the vertical wall of
+coral rock. There was just one narrow place where the waves rolled
+into a sort of cleft and did not break. Here was the "landing," then.
+
+Landing was an acrobatic feat. In you went on the crest of a wave,
+pointing for the place where the blue seas did not break into white.
+An instant after, you were in the quiet water inside of the surf. Jump
+out everybody and hold the boat! Then it was pick up the various
+instruments, and carry them for a quarter of a mile to high-water mark
+and beyond, over the sharp points of the reef.
+
+In one night we were fairly settled; in another the Hartford had
+sailed away, leaving us in our fairy paradise, where the corals and
+the fish were of all the brilliant hues of the rainbow, and where the
+whiteness of the sand, the emerald of the lagoon, and the turquoise of
+the ocean made a picture of color and form never to be forgotten.
+
+But where are the Frenchmen? The next morning there is the _Eclaireur_
+lying a mile or so out, and there is a boat with the bo'sun--_maître
+d'équipage_--pulling towards the surf. I wade out to the brink. He
+halloes:
+
+"Where is the landing, then?"
+
+"_Mais ici_"--Right here,--I say.
+
+"Yes, that's all very well for _persons_, but where do you land _les
+bagages_?"
+
+"_Mais ici_" I say again, and he says, "_Diable!_"
+
+But all the same he lands both persons and baggage in a neat,
+sailor-like way. In a couple of days our two parties of fifty persons
+had taken possession of this fairy isle. Observatories go up,
+telescopes, spectroscopes, photographic cameras are pointed and
+adjusted. The eventful day arrives. Everything is successful. Then
+comes the Hartford and takes us away, and a few days later comes the
+_Eclaireur_, and the Frenchmen are gone. The little island is left
+there, abandoned to the five natives who tend the sickly plantation of
+cocoa-palms, and live from year to year with no incident but the
+annual visit of "the blig" (Kanaka for brig), which brings their store
+of ship biscuit and molasses.
+
+[Illustration: "OBSERVATORIES GO UP."]
+
+Think of their stupendous experience! For years and years they have
+lived like that in the marvellous, continuous charm of the silent
+island. The "blig" had come and gone away this year, and there will
+be no more disturbance and discord for a twelve-month longer.
+
+  "Surely, surely, slumber is more sweet than toil, the shore
+  Than labor in the deep mid-ocean, wind, and wave, and oar,
+  Then rest ye, brother mariners, we will not wander more!"
+
+Not so! for here comes a great warship out of the East under a press
+of canvas. What event is this? See! she clews up her light sails and
+fires an eleven-inch gun! One of those guns of Mobile Bay. Then swarms
+out the starboard watch, one hundred and sixty strong, and a fleet of
+boats brings ashore these pale astronomers with those useless tubes
+that they point at the sky every night. But there are useful things
+too; cooking-stoves, and lumber, and bricks.
+
+What is all this? No sooner are these established than comes another
+ship and fires its gun! and another set of hardy sailormen pours out,
+and here is another party of madmen with tubes,--yes, and with
+cooking-stoves and lumber, too. Then comes the crowning, stupendous,
+and unspeakable event. The whole sun is hidden and the heavens are
+lighted up with pearly streamers! In the name of all the Polynesian
+gods, what is the meaning of all this?
+
+And then in a few days all these are gone. All the madmen. They have
+taken away the useless tubes, but they have left their houses
+standing. Their splendid, priceless, precious cook-stoves are here.
+See! here is a frying-pan! here are empty tin cans! and a keg of
+nails! They must have forgotten all this, madmen as they are!
+
+And the little island sinks back to its quiet and its calm. The lagoon
+lies placid like a mirror. The slow sea breaks eternally on the outer
+reef. The white clouds sail over day by day. The seabirds come back to
+their haunts,--the fierce man-of-war birds, the gentle, soft-eyed
+tern. But we, whose island home was thus invaded--are we the same? Was
+this a dream? Will it happen again next year? every year? What indeed
+was it that happened,--or in fact, did it happen at all? Is it not a
+dream, indeed?
+
+If we left those peaceful Kanakas to their dream, we Americans have
+brought ours away with us. Who will forget it? Which of us does not
+wish to be in that peaceful fairyland once more? That is the personal
+longing. But we have all come back, each one with his note-books full;
+and in a few weeks the stimulus of accustomed habit has taken
+possession of us again. Right and wrong are again determined by
+"municipal sanctions." We have become useful citizens once more.
+Perhaps it is just as well. We should have been poor poets, and we do
+not forget. So ends the astronomer's voyage to fairyland.
+
+[Illustration]
+
+
+
+
+HALOS--PARHELIA--THE SPECTRE OF THE BROCKEN, ETC
+
+(FROM THE ATMOSPHERE.)
+
+BY CAMILLE FLAMMARION.
+
+
+[Illustration]
+
+Treatises on meteorology have not, up to the present day, classified
+with sufficient regularity the divers optical phenomena of the air.
+Some of these phenomena have, however, been seen but rarely, and have
+not been sufficiently studied to admit of their classification. We
+have examined the common phenomenon of the rainbow and we have seen
+that it is due to the refraction and reflection of light on drops of
+water, and that it is seen upon the opposite side of the sky to the
+sun in day-time, or the moon at night. We are now about to consider an
+order of phenomena which are of rarer occurrence, but which have this
+property in common with the rainbow, viz., that they take place also
+upon the side of the sky opposite to the sun. These different optical
+effects are classed together under the name of _anthelia_ (from
+Greek, opposite to, and Greek, the sun). The optical phenomena which
+occur on the same side as, or around the sun, such as halos, parhelia,
+etc., will be dealt with later on.
+
+Before coming to the anthelia, properly so called, or to the colored
+rings which appear around a shadow, it is as well first to note the
+effects produced on the clouds and mists that are facing the sun when
+it rises or sets.
+
+Upon high mountains, the shadow of the mountain is often seen thrown
+either upon the surface of the lower mists or upon the neighboring
+mountains, and projected opposite to the sun almost horizontally. I
+once saw the shadow of the Righi very distinctly traced upon Mount
+Pilate, which is situated to the west of the Righi, on the other side
+of the Lake of Lucerne. This phenomenon occurs a few minutes after
+sunrise, and the triangular form of Righi is delineated in a shape
+very easy to recognize.
+
+The shadow of Mont Blanc is discerned more easily at sunset. MM.
+Bravais and Martins, in one of their scientific ascents, noticed it
+under specially favorable circumstances, the shadow being thrown upon
+the snow-covered mountains, and gradually rising in the atmosphere
+until it reached a height of 1°, still remaining quite visible. The
+air above the cone of the shadow was tinted with that rosy purple
+which is seen, in a fine sunset, coloring the lofty peaks. "Imagine,"
+says Bravais, "the other mountains also projecting, at the same
+moment, their shadows into the atmosphere, the lower parts dark and
+slightly greenish, and above each of these shadows the rosy surface,
+with the deeper rose of the belt which separates it from them; add to
+this the regular contour of the cones of the shadow, principally at
+the upper edge, and lastly, the laws of perspective causing all these
+lines to converge the one to the other toward the very summit of the
+shadow of Mont Blanc; that is to say, to the point of the sky where
+the shadows of our own selves were; and even then one will have but a
+faint idea of the richness of the meteorological phenomenon displayed
+before our eyes for a few instants. It seemed as though an invisible
+being was seated upon a throne surrounded by fire, and that angels
+with glittering wings were kneeling before him in adoration."
+
+Among the natural phenomena which now attract our attention, but fail
+to excite our surprise, there are some which possess the
+characteristics of a supernatural intervention. The names which they
+have received still bear witness to the terror which they once
+inspired; and even to-day, when science has stripped them of their
+marvellous origin, and explained the causes of their production, these
+phenomena have retained a part of their primitive importance, and are
+welcomed by the _savant_ with as much interest as when they were
+attributed to divine agency. Out of a large and very diverse number, I
+will first select the _Spectre of the Brocken_.
+
+The Brocken is the highest mountain in the picturesque Hartz chain,
+running through Hanover, being three hundred and thirty feet above the
+level of the sea.
+
+One of the best descriptions of this phenomenon is given by the
+traveller Hane, who witnessed it on the 23d of May, 1797. After having
+ascended no less than thirty miles to the summit, he had the good
+fortune at last to contemplate the object of his curiosity. The sun
+rose at about four o'clock, the weather being fine, and the wind
+driving off to the west the transparent vapors which had not yet had
+time to be condensed into clouds. About a quarter-past four, Hane saw
+in this direction a human figure of enormous dimensions. A gust of
+wind nearly blowing off his hat at that moment, he raised his hand to
+secure it, and the colossal figure imitated his action. Hane, noticing
+this, at once made a stooping movement, and this was also reproduced
+by the spectre. He then called another person to him, and placing
+themselves in the very spot where the apparition was first seen, the
+pair kept their eyes fixed on the Achtermannshohe, but saw nothing.
+After a short interval, however, two colossal figures appeared, which
+repeated the gestures made by them, and then disappeared.
+
+Some few years ago, in the summer of 1862, a French artist, M.
+Stroobant, witnessed and carefully sketched this phenomenon, which is
+drawn in full-page illustration, opposite p. 272. He had slept at the
+inn of the Brocken, and rising at two in the morning, he repaired to
+the plateau upon the summit in the company of a guide. They reached
+the highest point just as the first glimmer of the rising sun enabled
+them to distinguish clearly objects at a great distance. To use M.
+Stroobant's own words, "My guide, who had for some time appeared to be
+walking in search of something, suddenly led me to an elevation whence
+I had the singular privilege of contemplating for a few instants the
+magnificent effect of mirage, which is termed the Spectre of the
+Brocken. The appearance is most striking. A thick mist, which seemed
+to emerge from the clouds like an immense curtain, suddenly rose to
+the west of the mountain, a rainbow was formed, then certain
+indistinct shapes were delineated. First, the large tower of the inn
+was reproduced upon a gigantic scale; after that we saw our two selves
+in a more vague and less exact shape, and these shadows were in each
+instance surrounded by the colors of the rainbow, which served as a
+frame to this fairy picture. Some tourists who were staying at the inn
+had seen the sun rise from their windows, but no one had witnessed the
+magnificent spectacle which had taken place on the other side of the
+mountain."
+
+Sometimes these spectres are surrounded by colored concentric arcs.
+Since the beginning of the present century, treatises on meteorology
+designate, under the name of the _Ulloa circle_, the pale external
+arch which surrounds the phenomenon, and this same circle has
+sometimes been called the "white rainbow." But it is not formed at the
+same angular distance as the rainbow, and, although pale, it often
+envelops a series of interior colored arcs.
+
+[Illustration: "THE SPECTRE OF THE BROCKEN"]
+
+Ulloa, being in company with six fellow-travellers upon the Pambamarca
+at daybreak one morning, observed that the summit of the mountain was
+entirely covered with thick clouds, and that the sun, when it rose,
+dissipated them, leaving only in their stead light vapors, which it
+was almost impossible to distinguish. Suddenly, in the opposite
+direction to where the sun was rising, "each of the travellers beheld,
+at about seventy feet from where he was standing, his own image
+reflected in the air as in a mirror. The image was in the centre of
+three rainbows of different colors, and surrounded at a certain
+distance by a fourth bow with only one color. The inside color of each
+bow was carnation or red, the next shade was violet, the third yellow,
+the fourth straw color, the last green. All these bows were
+perpendicular to the horizon; they moved in the direction of, and
+followed, the image of the person they enveloped as with a glory." The
+most remarkable point was that, although the seven spectators were
+standing in a group, each person only saw the phenomenon in regard to
+his own person, and was disposed to disbelieve that it was repeated in
+respect to his companions. The extent of the bows increased
+continually and in proportion to the height of the sun; at the same
+time their colors faded away, the spectre became paler and more
+indistinct, and finally the phenomenon disappeared altogether. At the
+first appearance the shape of the bows was oval, but toward the end
+they became quite circular. The same apparition was observed in the
+polar regions by Scoresby, and described by him. He states that the
+phenomenon appears whenever there is mist and at the same time shining
+sun. In the polar seas, whenever a rather thick mist rises over the
+ocean, an observer, placed on the mast, sees one or several circles
+upon the mist.
+
+[Illustration: THE ULLOA CIRCLE.]
+
+These circles are concentric, and their common centre is in the
+straight line joining the eye of the observer to the sun, and extended
+from the sun toward the mist. The number of circles varies from one to
+five; they are particularly numerous and well colored when the sun is
+very brilliant and the mist thick and low. On July 23, 1821, Scoresby
+saw four concentric circles around his head. The colors of the first
+and of the second were very well defined; those of the third, only
+visible at intervals, were very faint, and the fourth only showed a
+slight greenish tint.
+
+The meteorologist Kaemtz has often observed the same fact in the Alps.
+Whenever this shadow was projected upon a cloud, his head appeared
+surrounded by a luminous aureola.
+
+To what action of light is this phenomenon due? Bouguer is of opinion
+that it must be attributed to the passage of light through icy
+particles. Such, also, is the opinion of De Saussure, Scoresby, and
+other meteorologists.
+
+In regard to the mountains, as we cannot assure ourselves directly of
+the fact by entering the clouds, we are reduced to conjecture. The
+aerostat traversing the clouds completely, and passing by the very
+point where the apparition is seen, affords one an opportunity of
+ascertaining the state of the cloud. This observation I have been able
+to make, and so to offer an explanation of the phenomenon.
+
+As the balloon sails on, borne forward by the wind, its shadow travels
+either on the ground or on the clouds. This shadow is, as a rule,
+black, like all others; but it frequently happens that it appears
+alone on the surface of the ground, and thus appears luminous.
+Examining this shadow by the aid of a telescope, I have noticed that
+it is often composed of a dark nucleus and a penumbra of the shape of
+an aureola. This aureola, frequently very large in proportion to the
+diameter of the central nucleus, eclipses it to the naked eye, so that
+the whole shadow appears like a nebulous circle projected in yellow
+upon the green ground of the woods and meadows. I have noticed, too,
+that this luminous shadow is generally all the more strongly marked in
+proportion to the greater humidity of the surface of the ground.
+
+Seen upon the clouds, this shadow sometimes presents a curious aspect.
+I have often, when the balloon emerged from the clouds into the clear
+sky, suddenly perceived, at twenty or thirty yards' distance, a second
+balloon distinctly delineated, and apparently of a grayish color,
+against the white ground of the clouds. This phenomenon manifests
+itself at the moment when the sun re-appears. The smallest details of
+the car can be made out clearly, and our gestures are strikingly
+reproduced by the shadow.
+
+[Illustration: THE SHADOW OF THE BALLOON WAS SEEN BY US.]
+
+On April 15, 1868, at about half-past three in the afternoon, we
+emerged from a stratum of clouds, when the shadow of the balloon was
+seen by us, surrounded by colored concentric circles, of which the car
+formed the centre. It was very plainly visible upon a yellowish white
+ground. A first circle of pale blue encompassed this ground and the
+car in a kind of ring. Around this ring was a second of a deeper
+yellow, then a grayish red zone, and lastly as the exterior
+circumference, a fourth circle, violet in hue, and imperceptibly
+toning down into the gray tint of the clouds. The slightest details
+were clearly discernible--net, robes, and instruments. Every one of
+our gestures was instantaneously reproduced by the aerial spectres.
+The anthelion remained upon the clouds sufficiently distinct, and for
+a sufficiently long time, to permit of my taking a sketch in my
+journal and studying the physical condition of the clouds upon which
+it was produced. I was able to determine directly the circumstances of
+its production. Indeed, as this brilliant phenomenon occurred in the
+midst of the very clouds which I was traversing, it was easy for me to
+ascertain that these clouds were not formed of frozen particles. The
+thermometer marked 2° above zero. The hygrometer marked a maximum of
+humidity experienced, namely, seventy-seven at three thousand seven
+hundred and seventy feet, and the balloon was then at four thousand
+six hundred feet, where the humidity was only seventy-three. It is
+therefore certain that this is a phenomenon of the diffraction of
+light simply produced by the vesicles of the mist.
+
+The name of diffraction is given to all the modifications which the
+luminous rays undergo when they come in contact with the surface of
+bodies. Light, under these circumstances, is subject to a sort of
+deviation, at the same time becoming decomposed, whence result those
+curious appearances in the shadows of objects which were observed for
+the first time by Grimaldi and Newton.
+
+The most interesting phenomena of diffraction are those presented by
+_gratings_, as are technically denominated the systems of linear and
+very narrow openings situated parallel to one another and at very
+small intervals. A system of this kind may be realized by tracing with
+a diamond, for instance, on a pane of glass equidistant lines very
+close together. As the light would be able to pass in the interstices
+between the strokes, whereas it would be stopped in the points
+corresponding to those where the glass was not smooth, there is, in
+reality, an effect produced as if there were a series of openings very
+near to each other. A hundred strokes, about 1/25th of an inch in
+length, may thus be drawn without difficulty. The light is then
+decomposed in spectra, each overlapping the other. It is a phenomenon
+of this kind which is seen when we look into the light with the eye
+half closed; the eyelashes in this case, acting as a net-work or
+grating. These net-works may also be produced by reflection, and it is
+to this circumstance that are due the brilliant colors observed when a
+pencil of luminous rays is reflected on a metallic surface regularly
+striated.
+
+To the phenomena of gratings must be attributed, too, the colors,
+often so brilliant, to be seen in mother-of-pearl. This substance is
+of a laminated structure; so much so, that in carving it the different
+folds are often cut in such a way as to form a regular net-work upon
+the surface. It is, again, to a phenomenon of this sort that are due
+the rainbow hues seen in the feathers of certain birds, and sometimes
+in spiders' webs. The latter, although very fine, are not simple, for
+they are composed of a large number of pieces joined together by a
+viscous substance, and thus constitute a kind of net-work.
+
+If the sun is near the horizon, and the shadow of the observer falls
+upon the grass, upon a field of corn, or other surface covered with
+dew, there is visible an aureola, the light of which is especially
+bright about the head, but which diminishes from below the middle of
+the body. This light is due to the reflection of light by the moist
+stubble and the drops of dew. It is brighter about the head, because
+the blades that are near where the shadow of the head falls expose to
+it all that part of them which is lighted up, whereas those farther
+off expose not only the part which is lighted up, but other parts
+which are not, and this diminishes the brightness in proportion as
+their distance from the head increases. The phenomenon is seen
+whenever there is simultaneously mist and sun. This fact is easily
+verified upon a mountain. As soon as the shadow of a mountaineer is
+projected upon a mist, his head gives rise to a shadow surrounded by a
+luminous aureola.
+
+[Illustration: FOG-BOW SEEN FROM THE MATTERHORN.]
+
+_The Illustrated London News_ of July 8, 1871, illustrates one of
+these apparitions, "The Fog-Bow, seen from the Matterhorn," observed
+by E. Whymper in this celebrated region of the Alps. The observation
+was taken just after the catastrophe of July 14, 1865; and by a
+curious coincidence, two immense white aerial crosses projected into
+the interior of the external arc. These two crosses were no doubt
+formed by the intersection of circles, the remaining parts of which
+were invisible. The apparition was of a grand and solemn character,
+further increased by the silence of the fathomless abyss into which
+the four ill-fated tourists had just been precipitated.
+
+[Illustration]
+
+Other optical appearances of an analogous kind are manifested under
+different conditions. Thus, for instance, if any one, turning his back
+to the sun, looks into water, he will perceive the shadow of his head,
+but always very much deformed. At the same time he will see starting
+from this very shadow what seem to be luminous bodies, which dart
+their rays in all directions with inconceivable rapidity, and to a
+great distance. These luminous appearances--these aureola rays--have,
+in addition to the darting movement, a rapid rotary movement around
+the head.
+
+[Illustration]
+
+
+
+
+THE PLANET VENUS
+
+BY AGNES M. CLERKE.
+
+
+
+
+I.
+
+HESPERUS AND PHOSPHOR.
+
+
+[Illustration]
+
+The radiant planet that hangs on the skirts of dusk and dawn
+
+     "like a jewel in an Ethiop's ear,"
+
+has been known and sung by poets in all ages. Its supremacy over the
+remainder of the starry host is recognized in the name given it by the
+Arabs, those nomad watchers of the skies, for while they term the moon
+"El Azhar," "the Brighter One," and the sun and moon together "El
+Azharan," "the Brighter Pair," they call Venus "Ez Zahra," the bright
+or shining one _par excellence_, in which sense the same word is used
+to describe a flower. This "Flower of Night" is supposed to be no
+other than the white rose into which Adonis was changed by Venus in
+the fable which is the basis of all early Asiatic mythology. The
+morning and evening star is thus the celestial symbol of that union
+between earth and heaven in the vivifying processes of nature,
+typified in the love of the goddess for a mortal.
+
+The ancient Greeks, on the other hand, not unnaturally took the star,
+which they saw alternately emerging from the effulgence of the rising
+and setting sun, in the east and in the west, for two distinct bodies,
+and named it differently according to the time of its appearance. The
+evening star they called Hesperus, and from its place on the western
+horizon, fabled an earthly hero of that name, the son of Atlas, who
+from the slopes of that mountain on the verge of the known world used
+to observe the stars until eventually carried off by a mighty wind,
+and so translated to the skies. These divine honors were earned by his
+piety, wisdom, and justice as a ruler of men, and his name long shed a
+shimmering glory over those Hesperidean regions of the earth, where
+the real and unreal touched hands in the mystical twilight of the
+unknown.
+
+But the morning star shone with a different significance as the herald
+of the day, the torchbearer who lights the way for radiant Aurora on
+her triumphal progress through the skies. Hence he was called
+Eosphorus, or Phosphorus, the bearer of the dawn, translated into
+Latin as Lucifer, the Light-bearer. The son of Eos, or Aurora, and the
+Titan Astraeus, he was of the same parentage as the other multitude of
+the starry host, to whom a similar origin was ascribed, and from whom
+in Greek mythology he was evidently believed to differ only in the
+superior order of his brightness. Homer, who mentions the planet in
+the following passage:
+
+  "But when the star of Lucifer appeared,
+  The harbinger of light, whom following close,
+  Spreads o'er the sea the saffron-robed morn."
+
+                              (LORD DERBY'S "Iliad.")
+
+recognizes no distinction between those celestial nomads, the planets,
+"wandering stars," as the Arabs call them, which visibly change their
+position relatively to the other stars, and the latter, whose places
+on the sphere are apparently fixed and immutable. In this he and his
+compatriots were far behind the ancient Egyptians, who probably
+derived their knowledge from still earlier speculators in Asia, for
+they not only observed the movements of some at least of the planets,
+but believed that Mercury and Venus revolved as satellites round the
+sun, which in its turn circled round our lesser world. Pythagoras is
+said to have been the first to identify Hesperus with Phosphor, as the
+
+  "Silver planet both of eve and morn,"
+
+and by Plato the same fact is recognized. The other planets, all of
+which had, according to him, been originally named in Egypt and Syria,
+have each its descriptive title in his nomenclature. Thus the
+innermost, "the Star of Mercury," is called Stilbon, "the Sparkler,"
+Mars, Pyroeis, "the Fiery One," while Jupiter, the planet of the
+slowest course but one, is designated as Phaeton, and Saturn, the
+tardiest of all, Phaenon. These names were in later times abandoned in
+favor of those of the divinities to whom they were respectively
+dedicated, unalterably associated now with the days of the week, over
+which they have been selected to preside.
+
+The Copernican theory, which once and forever "brushed the cobwebs out
+of the sky," by clearing away the mists of pre-existing error, first
+completely explained the varying positions of the Shepherd's star,
+irradiating the first or last watch of night, according to her
+alternate function as the follower or precursor of the sun. As she
+travels on a path nearer to him by more than twenty-five and a half
+million miles than that of the earth, she is seen by us on each side
+of him in turn after passing behind or in front of him. The points at
+which her orbit expands most widely to our eyes--an effect of course
+entirely due to perspective, as her distance from the sun is not then
+actually increased--are called her eastern and western elongations;
+that at which she passes by the sun on the hither side her inferior,
+and on the farther side her superior conjunction. At both conjunctions
+she is lost to our view, since she accompanies the sun so closely as
+to be lost in his beams, rising and setting at the same time, and
+travelling with him in his path through the heavens during the day.
+When at inferior conjunction, or between us and the sun, she turns her
+dark hemisphere to us like the new moon, and would consequently be
+invisible in any case, but when in the opposite position, shows us her
+illuminated face, and is literally a day star, invisible only because
+effaced by the solar splendor. It is as she gradually separates from
+him, after leaving this latter position, circling over that half of
+her orbit which lies to the east of him, that she begins to come into
+view as an evening star, following him at a greater and greater
+distance, and consequently setting later, until she attains her
+greatest eastern elongation, divided from the sun about 45° of his
+visible circuit through the heavens, and consequently remaining above
+the horizon for some four hours after him. From this point she again
+appears to draw nearer to him until she passes on his hither side in
+inferior conjunction, from which she emerges on the opposite side to
+the westward, and begins to shine as a morning star, preceding him on
+his track, at a gradually increasing distance, until attaining her
+greatest westward elongation, and finally completing her cycle by
+returning to superior conjunction once more in a period of about five
+hundred and eighty-four days.
+
+Venus is thus Hesperus or Vesper, the evening star, when following the
+sun as she passes from beyond him in superior conjunction to inferior
+conjunction where she is nearest to the earth. As she again leaves him
+behind in her course from this point to the opposite one of superior
+conjunction, she appears in her second aspect as Phosphorus or
+Lucifer, "the sun of morning," and herald of the day, shining as
+
+                          "The fair star
+  That gems the glittering coronet of morn."
+
+
+
+
+II.
+
+THE PHASES OF VENUS.
+
+
+But the changes in the aspect of Venus due to her varying positions in
+her orbit are not confined to those which cause her to oscillate with
+a pendulum movement eastward and westward from the sun. The discovery
+that she undergoes phases exactly like those of the moon, followed
+that of the existence of Jupiter's satellites as the second great
+result achieved by the use of the telescope in the hands of Galileo.
+The fact that the planets were intrinsically dark bodies revolving
+round the sun, and reflecting its light, as he and Copernicus had
+maintained, thus received a further ocular demonstration. The
+Florentine astronomer describes in a letter to a friend how the
+planet, after emerging from superior conjunction as a morning star,
+gradually loses her rotundity on the side remote from the luminary,
+changing first to a half sphere and then to a waning crescent; until,
+after passing through the stage of absolute extinction when
+intervening between us and the sun, she re-appears as a morning star,
+and undergoes the same series of transformations in inverse order. The
+revelation was indeed so novel and unexpected, that when the slight
+deformation of the planet's shape was first detected by him, he did
+not venture to announce it in plain terms but veiled it, according to
+the prevailing fashion of the time, under a Latin anagram. His
+celebrated sentence--
+
+  "Haec immatura a me jam frustra leguntur."
+
+("Those incomplete observations are as yet read by me in vain.")
+
+forms, by transposing the letters, the more definite statement,
+
+  "Cynthiæ figuras æmulatur Mater Amorum."
+
+("The mother of the loves imitates the aspects of Diana.")
+
+that is to say, Venus vies with the phases of the moon. The discovery
+was an important one from its bearing on popular superstition ascribing
+to the planets special influences on human affairs, for since they were
+thus shown to transmit to us only borrowed light, belief in their
+beneficent or malefic powers over man's destinies received a rude shock.
+
+[Illustration: THE PHASES OP VENUS.]
+
+Galileo's announcement, published in September, 1610, when only a
+slight flattening of the planet's disk was visible, received absolute
+confirmation in the ensuing months, as she completed her full
+half-circle of change on February 24th of the following year, and
+consequently exhibited herself to him in all her varying aspects. It
+was the first time they had been looked upon by a human eye, since its
+unaided powers do not enable it to discern them, although one
+exception to this rule is said to have existed. This was the case of
+the Swiss mathematician Gauss, who, when a child, on being shown the
+crescent star through the telescope, exclaimed to his mother that it
+"was turned wrong"; the inference being that he recognized the
+reversal of the image in the field of the glass. If it were indeed so,
+he deserves to rank with the Siberian savage, who described the
+eclipses, or Jupiter's satellites; or the shoemaker of Breslau, who
+could see and declare the positions of those minute orbs.
+
+The phases exhibited to us by Venus are due to her moving in an orbit
+within that of the earth, at one side of which she is between us and
+the sun, while at the other this position is exactly reversed. We may
+compare her to a performer in a great celestial circus, lit by a
+central chandelier, and ourselves to spectators in an external ring,
+from which we see her at one time facing us with the light full on
+her, at the opposite point in complete shadow, and at the intermediate
+ones in varying degrees of illumination according to our changing
+views of her. The same illustration may serve to show why Venus is
+brightest, not when full, since she is then beyond the sun, and at the
+farthest possible point from us, but when she approaches us at
+inferior conjunction, more nearly by over one hundred and thirty
+million miles, and still shows us a crescent of her illuminated
+surface, before passing into the last phase of total obscuration. When
+actually nearest to us she is absolutely invisible, being then, like
+the new moon, between us and the sun. Her varying degrees of
+brilliancy, even when in the same phase, are thus accounted for by her
+alternate retreat from and advance towards us as she circles round the
+sun. Completing, as she does, her revolution in about seven months and
+a half, she would of course go through the whole series of her
+metamorphoses in that time, were the earth, from which we observe
+them, a fixed point. Their protraction instead, over a term of five
+hundred and eighty-four days, or more than nineteen months, is due to
+the simultaneous motion of the earth in the same direction, over her
+larger orbit in a longer period, causing the same relative position of
+the sister planet to recur only as often as she overtakes her in her
+career. Thus the hour and minute hands of a watch, moving at different
+rates of speed after meeting on the dial plate at twelve o'clock, will
+not again come together until five minutes past one, when the swifter
+paced of the two will have completed a revolution and a twelfth. But
+were we to retard the motion of the latter, reducing it to only twice
+that of its companion, they would always meet at the figure twelve, as
+it would exactly complete two circuits while the hour hand was
+performing one. Venus thus overtakes and passes the earth once in five
+hundred and eighty-four days, or nearly two and a half of her own
+years, constituting what is called her synodic period of apparent
+revolution as seen from this globe. She thus presents to us all the
+phases undergone by our own satellite during a lunar month, passing
+from new to full, and _vice versa_, through the various intervening
+gradations of form.
+
+The phases of Venus are amongst the most beautiful subjects for
+observation in a moderate telescope, as her silver bow, gradually
+brightening in the evening dusk, or fading in the dawn,
+
+  "On a bed of daffodil sky,"
+
+is, after the two greater luminaries that rule the day and night, the
+most brilliant object in the heavens.
+
+
+
+
+III.
+
+THE SILVER CROWN.
+
+
+The parallel between Venus and
+
+  "That orbed maiden with fire laden,
+   Whom mortals call the moon,"
+
+is carried a stage further. Most of us are familiar with the spectacle
+in which the Ancient Egyptians saw symbolized Horus on the lap of
+Isis, but which we more prosaically term "the old moon in the new
+moon's arms." The strongly illuminated half circle next the sun is
+then seen embracing with its horns a dusky sphere, contrasting with it
+as tarnished silver does with the newly burnished metal. The same
+phenomenon is occasionally, though very rarely, exhibited by Venus,
+while close to the sun at inferior injunction, when the shadowy form
+of the full orb is seen to shine dimly within her crescent with what
+is termed "the ashen light." More wonderful still, this "glimmering
+sphere" is then crowned, as with a silver halo, by a thin luminous
+arch, forming a secondary sickle facing the one nearest the sun, and
+doubtless due to the refraction of his rays round the globe of the
+planet, through the upper regions of her twilight atmosphere. This
+spectacle was first observed by the Jesuit Ricciolo, an opponent of
+the Copernican theory, on January 9th, 1643. He describes the planet
+as ruddy near the sun, yellowish in the middle, and of greenish blue
+on the side remote from the sun; while he also noted the bow of light
+limiting the dark hemisphere. Scarcely daring to trust his own
+eyesight, he ascribed these appearances, although he recorded them, to
+illusory reflection in the telescope.
+
+[Illustration: VENUS AT HER GREATEST BRILLIANCY.]
+
+They were again seen, however, by Derham about 1715, and six years
+later by Kirch, in Berlin, who has the following entry in his diary
+for Saturday, June 29, 1721:--"I found Venus in a region where the sky
+was not very clear. The planet was narrow, and I seemed to see its
+dark side, though this is almost incredible. The diameter of Venus was
+65", and its sickle seemed to tremble in the atmospheric vapors."
+Again, on March 8th, 1726, he records a similar observation. "We
+observed Venus with the twenty-six foot telescope. I perceived her
+dark side, and its edge seemed to describe a smaller circle than that
+of the light side, as is the case of the moon." This effect is due to
+irradiation, that is to say, to the glare from a bright surface,
+giving a deceptive enlargement to its apparent area. He again saw the
+dark side of the planet in October, 1759, as did Harding at Göttingen,
+with Herschel's ten-foot reflector, on January 24th, 1806. This latter
+observer saw it on this occasion stand out against the background of
+the sky as of a pale ashen green, while on February 28th following, it
+seemed to him of a pale reddish gray, like the color of the eclipsed
+moon.
+
+That the latter body should send to us from her nocturnal shadows
+sufficient light to be visible is easily explicable, since she is then
+flooded with earth-light reflected on her from a surface thirteen and
+one-half times greater than her own, and probably casting on her an
+illumination transcending our full moonlight in the same proportion.
+But the secondary light of Venus admits of no such explanation, since
+earth-light on her surface, diminished by 1/12000th part compared to
+what it is on that of the moon, would be quite insufficient to render
+her visible to our eyes. The phenomenon was therefore adduced as an
+argument for the habitability of the planets by Gruithuisen, of the
+Munich Observatory, who, writing early in this century, suggested that
+the ashen light of Venus might be due to general illuminations in
+celebration by her inhabitants of some periodically recurring
+festivity, The materials for a flare-up on so grand a scale would, he
+thought, exist in abundance, as he conjectured the vegetation of our
+planetary neighbor to be more luxuriant than that of our Brazilian
+forests. The phosphorescence of the Aphroditean oceans, warm and
+teeming with life, as they are held to be by Zollner, was advanced as
+an explanatory hypothesis, with scarcely more plausibility, by
+Professor Safarik, while others have resorted to the supposition of
+atmospheric or electrical luminosity producing on a large scale some
+such display as that of the aurora borealis.
+
+Professor Vogel, of Berlin, who himself saw part of the night-side of
+Venus, in its semi-obscurity in November, 1871, ascribed its
+visibility to a twilight effect caused by a very extensive atmosphere.
+The light thus transmitted to us by aerial diffusion and giving the
+ashen light, is reflected sunlight, while that sent by the luminous
+arc on its edge is direct sunlight, refracted, or bent round to us,
+from behind the planet. The silver selvedge of the dawn edging the
+dark limb may consequently be the brightest part of the broken nimbus
+that then seems to surround her.
+
+A similar appearance is observed during transits of Venus, when she
+passes directly between us and the actual solar disk. A silver thread
+is then seen encircling that side of the planet which has not yet
+entered on the face of the sun or "a shadowy nebulous ring," as it was
+described by Mr. Macdonnell at Eden, surrounds the whole planetary
+disk when two-thirds of it have passed the solar edge. As it moves off
+it, the same aureole again becomes visible, testifying to the
+existence of an atmosphere of considerable extent exterior to the
+sharply outlined surface ordinarily visible. The shimmering haze of
+reflected sunlight which perpetually enfolds her is only made apparent
+to us under exceptional circumstances which cut off some portion of
+her more immediate light, just as we see the motes in the air
+illuminated by a candle if we hide the actual flame from our eyes. The
+perennial twilight which seems to reign over the nocturnal hemisphere
+of Venus may compensate, perhaps, for the want of a satellite to
+modify its darkness.
+
+The great prolongation at other times of the horns of her crescent, so
+as to embrace almost her entire circumference with a tenuous ring of
+light, is doubtless due to the same cause, as their visibility should
+otherwise be limited to a half segment of a circle. The regions thus
+shining to us are obviously those on which the sun has not yet set,
+his appearance above the horizon being prolonged, as in our own case,
+by refraction, though to a much larger extent. The magnitude of the
+sun's disk as seen from Venus, a third larger than it appears to us,
+is also adducted by Mr. Proctor in his posthumous work, "The Old and
+the New Astronomy," edited and completed by Mr. A.C. Ranyard, as an
+element in extending the illumination of Venus to more than a
+hemisphere of her surface. As his diameter there is 44-1/4°, a zone
+of more than 22° wide outside the sunward hemisphere is he thinks
+illuminated by direct though partial sunlight, the orb being
+throughout this tract still partially above the horizon.
+
+[Illustration: GEOGRAPHICAL ASPECT OF VENUS.]
+
+
+
+
+[Illustration]
+
+
+THE STARS
+
+(FROM STARLAND.)
+
+BY SIR ROBERT S. BALL.
+
+
+[Illustration]
+
+The group of bodies which cluster around our sun forms a little
+island, so to speak, in the extent of infinite space. We may
+illustrate this by a map in which we shall endeavor to show the stars
+placed at their proper relative distances. We first open the compasses
+one inch, and thus draw a little circle to represent the path of the
+earth. We are not going to put in all the planets. We take Neptune,
+the outermost, at once. To draw its path I open the compasses to
+thirty inches, and draw a circle with that radius. That will do for
+our solar system, though the comets no doubt will roam beyond these
+limits. To complete our map we ought of course to put in some stars.
+There are a hundred million to choose from, and we shall begin with
+the brightest. It is often called the Dog Star, but astronomers know
+it better as Sirius. Let us see where it is to be placed on our map.
+Sirius is beyond Neptune, so it must be outside somewhere. Indeed, it
+is a good deal further off than Neptune; so I try at the edge of the
+drawing-board; I have got a method of making a little calculation that
+I do not intend to trouble you with, but I can assure you that the
+results it leads me to are quite correct; they show me that this board
+is not big enough. But could a board which was big enough fit into
+this lecture theatre? Here, again, I make my little calculations, and
+I find that there would not be room for a board sufficiently great; in
+fact, if I put the sun here at one end, with its planets around it?
+Sirius would be too near on the same scale if it were at the further
+corner. The board would have to go out through the wall of the
+theatre, out through London. Indeed, big as London is, it would not be
+large enough to contain the drawing-board that I should require. It
+would have to stretch about twenty miles from where we are now
+assembled. We may therefore dismiss any hope of making a practical map
+of our system on this scale if Sirius is to have its proper place. Let
+us, then, take some other star. We shall naturally try with the
+nearest of all. It is one that we do not know in this part of the
+world, but those that live in the southern hemisphere are well
+acquainted with it. The name of this star is Alpha Centauri. Even for
+this star we should require a drawing three or four miles long if the
+distance from the earth to the sun is to be taken as one inch. You see
+what an isolated position our sun and his planets occupy. The members
+of the family are all close together, and the nearest neighbors are
+situated at enormous distances. There is a good reason for this
+separation. The stars are very pretty and perfectly harmless to us
+where they are at present situated. They might be very troublesome
+neighbors if they were very much closer to our system. It is therefore
+well they are so far off; they would be constantly making disturbances
+in the sun's family if they were near at hand. Sometimes they would be
+dragging us into unpleasantly great heat by bringing us too close to
+the sun, or producing a coolness by pulling us away from the sun,
+which would be quite as disagreeable.
+
+
+The Stars are Suns.
+
+We are about to discuss one of the grandest truths in the whole of
+nature. We have had occasion to see that this sun of ours is a
+magnificent globe immensely larger than the greatest of his planets,
+while the greatest of these planets is immensely larger than this
+earth; but now we are to learn that our sun is, indeed, only a star
+not nearly so bright as many of those which shine over our heads every
+night. We are comparatively close to the sun, so that we are able to
+enjoy his beautiful light and cheering heat. Each of those other
+myriads of stars is a sun, and the splendor of those distant suns is
+often far greater than that of our own. We are, however, so enormously
+far from them that they appear dwindled down to insignificance. To
+judge impartially between our sun or star and such a sun or star as
+Sirius we should stand halfway between the two; it is impossible to
+make a fair estimate when we find ourselves situated close to one star
+and a million times as far from the other. After allowance is made for
+the imperfections of our point of view, we are enabled to realize the
+majestic truth that the sun is no more than a star, and that the other
+stars are no less than suns. This gives us an imposing idea of the
+extent and magnificence of the universe in which we are situated. Look
+lip at the sky at night--you will see a host of stars; try to think
+that every one of them is itself a sun. It may probably be that those
+suns have planets circling round them, but it is hopeless for us to
+expect to see such planets. Were you standing on one of those stars
+and looking towards our system, you would not perceive the sun to be
+the brilliant and gorgeous object that we know so well. If you could
+see him at all, he would merely seem like a star, not nearly as bright
+as many of those you can see at night. Even if you had the biggest of
+telescopes to aid your vision, you could never discern from one of
+these bodies the planets which surround the sun, no astronomer in the
+stars could see Jupiter, even if his sight were a thousand times as
+powerful as any sight or telescope that we know. So minute an object
+as our earth would, of course, be still more hopelessly beyond the
+possibility of vision.
+
+
+The Number of the Stars.
+
+To count the stars involves a task which lies beyond the power of man
+to accomplish. Even without the aid of any telescope, we can see a
+great multitude of stars from this part of the world. There are also
+many constellations in the southern hemisphere which never appear
+above our horizon. If, however, we were to go to the equator, then, by
+waiting there for a twelve-month, all the stars in the heavens would
+have been successively exposed to view. An astronomer, Houzeau, with
+the patience to count them, enumerated about six thousand. This is the
+naked-eye estimate of the star-population of the heavens; but if
+instead of relying on unaided vision, you get the assistance of a
+little telescope, you will be astounded at the enormous multitude of
+stars which are disclosed.
+
+[Illustration: FIG 1. THE GREAT BEAR AND THE POLE.]
+
+An ordinary opera-glass or binocular is a very useful instrument for
+looking at the stars in the heavens. If you employ an instrument of
+this sort, you will be amazed to find that the heavens teem with
+additional hosts of stars that your unaided vision would never have
+given you knowledge of. Any part of the sky may be observed; but, just
+to give an illustration, I shall take one special region, namely, that
+of the Great Bear (Fig. 1). The seven well-known stars are here shown,
+four of which form a sort of oblong, while the other three represent
+the tail. I would like you to make this little experiment. On a fine
+clear night, count how many stars there are within this oblong; they
+are all very faint, but you will be able to see a few, and, with good
+sight, and on a clear night, you may see perhaps ten. Next take your
+opera-glass and sweep it over the same region; if you will carefully
+count the stars it shows, you will find fully two hundred; so that
+the opera-glass has, in this part of the sky, revealed nearly twenty
+times as many stars as could be seen without its aid. As six thousand
+stars can be seen by the eye all over the heavens, we may fairly
+expect that twenty times that number--that is to say, one hundred and
+twenty thousand stars--could be shown by the opera-glass over the
+entire sky. Let us go a step further, and employ a telescope, the
+object-glass of which is three inches across. This is a useful
+telescope to have, and, if a good one, will show multitudes of
+pleasing objects, though an astronomer would not consider it very
+powerful. An instrument like this, small enough to be carried in the
+hand, has been applied to the task of enumerating the stars in the
+northern half of the sky, and three hundred and twenty thousand stars
+were counted. Indeed, the actual number that might have been seen with
+it is considerably greater, for when the astronomer Argelander made
+this memorable investigation he was unable to reckon many of the stars
+in localities where they lay very close together. This grand count
+only extended to half the sky, and, assuming that the other half is as
+richly inlaid with stars, we see that a little telescope like that we
+have supposed will, when swept over the heavens, reveal a number of
+stars which exceeds that of the population of any city in England
+except London. It exhibits more than one hundred times as many stars
+as our eyes could possibly reveal. Still, we are only at the beginning
+of the count; the very great telescopes add largely to the number.
+There are multitudes of stars which in small instruments we cannot
+see, but which are distinctly visible from our great observatories.
+That telescope would be still but a comparatively small one which
+would show as many stars in the sky as there are people living in the
+mighty city of London; and with the greatest instruments, the tale of
+stars has risen to a number far greater than that of the entire
+population of Great Britain.
+
+In addition to those stars which the largest telescopes show us, there
+are myriads which make their presence evident in a wholly different
+way. It is only in quite recent times that an attempt has been made to
+develop fully the powers of photography in representing the celestial
+objects. On a photographic plate which has been exposed to the sky in
+a great telescope the stars are recorded by thousands. Many of these
+may, of course, be observed with a good telescope, but there are not a
+few others which no one ever saw in a telescope, which apparently no
+one ever could see, though the photograph is able to show them. We do
+not, however, employ a camera like that which the photographer uses
+who is going to take your portrait. The astronomer's plate is put into
+his telescope, and then the telescope is turned towards the sky. On
+that plate the stars produce their images, each by its own light. Some
+of these images are excessively faint, but we give a very long
+exposure of an hour or two hours; sometimes as much as four hours'
+exposure is given to a plate so sensitive that a mere fraction of a
+second would sufficiently expose it during the ordinary practice of
+taking a photograph in daylight. We thus afford sufficient time to
+enable the fainter objects to indicate their presence upon the
+sensitive film. Even with an exposure of a single hour a picture
+exhibiting sixteen thousand stars has been taken by Mr. Isaac Roberts,
+of Liverpool. Yet the portion of the sky which it represents is only
+one ten-thousandth part of the entire heavens. It should be added that
+the region which Mr. Roberts has photographed is furnished with stars
+in rather exceptional profusion.
+
+Here, at last, we have obtained some conception of the sublime scale
+on which the stellar universe is constructed. Yet even these plates
+cannot represent all the stars that the heavens contain. We have every
+reason for knowing that with larger telescopes, with more sensitive
+plates, with more prolonged exposures, ever fresh myriads of stars
+will be brought within our view.
+
+You must remember that every one of these stars is truly a sun, a
+lamp, as it were, which doubtless gives light to other objects in its
+neighborhood as our sun sheds light upon this earth and the other
+planets. In fact, to realize the glories of the heavens you should try
+to think that the brilliant points you see are merely the luminous
+points of the otherwise invisible universe.
+
+Standing one fine night on the deck of a Cunarder we passed in open
+ocean another great Atlantic steamer. The vessel was near enough for
+us to see not only the light from the mast-head but also the little
+beams from the several cabin ports; and we could see nothing of the
+ship herself. Her very existence was only known to us by the twinkle
+of these lights. Doubtless her passengers could see, and did see, the
+similar lights from our own vessel, and they probably drew the correct
+inference that these lights indicated a great ship.
+
+Consider the multiplicity of beings and objects in a ship: the
+captain and the crew, the passengers, the cabins, the engines, the
+boats, the rigging, and the stores. Think of all the varied interests
+there collected and then reflect that out on the ocean, at night, the
+sole indication of the existence of this elaborate structure was given
+by the few beams of light that happened to radiate from it. Now raise
+your eyes to the stars; there are the twinkling lights. We cannot see
+what those lights illuminate, we can only conjecture what untold
+wealth of non-luminous bodies may also lie in their vicinity; we may,
+however, feel certain that just as the few gleaming lights from a ship
+are utterly inadequate to give a notion of the nature and the contents
+of an Atlantic steamer, so are the twinkling stars utterly inadequate
+to give even the faintest conception of the extent and the interest of
+the universe. We merely see self-luminous bodies, but of the
+multitudes of objects and the elaborate systems of which these bodies
+are only the conspicuous points we see nothing and we know very
+little. We are, however, entitled to infer from an examination of our
+own star--the sun--and of the beautiful system by which it is
+surrounded, that these other suns may be also splendidly attended.
+This is quite as reasonable a supposition as that a set of lights seen
+at night on the Atlantic Ocean indicates the existence of a fine ship.
+
+
+The Clusters of Stars.
+
+On a clear night you can often see, stretching across the sky, a track
+of faint light, which is known to astronomers as the "Milky Way." It
+extends below the horizon, and then round the earth to form a girdle
+about the heavens. When we examine the Milky Way with a telescope we
+find, to our amazement, that it consists of myriads of stars, so small
+and so faint that we are not able to distinguish them individually; we
+merely see the glow produced from their collective rays. Remembering
+that our sun is a star, and that the Milky Way surrounds us, it would
+almost seem as if our sun were but one of the host of stars which form
+this cluster.
+
+There are also other clusters of stars, some of which are exquisitely
+beautiful telescopic spectacles. I may mention a celebrated pair of
+these objects which lies in the constellation of Perseus. The sight of
+them in a great telescope is so imposing that no one who is fit to
+look through a telescope could resist a shout of wonder and admiration
+when first they burst on his view. But there are other clusters. Here
+is a picture of one which is known as the "Globular Cluster in the
+Centaur" (Fig. 2). It consists of a ball of stars, so far off that,
+however large these several suns may actually be, they have dwindled
+down to extremely small points of light. A homely illustration may
+serve to show the appearance which a globular cluster presents in a
+good telescope. I take a pepper-caster, and on a sheet of white paper
+I begin to shake out the pepper until there is a little heap at the
+centre and other grains are scattered loosely about. Imagine that
+every one of those grains of pepper was to be transformed into a tiny
+electric light, and then you have some idea of what a cluster of stars
+would look like when viewed through a telescope of sufficient power.
+There are multitudes of such groups scattered through the depths of
+space. They require our biggest telescopes to show them adequately. We
+have seen that our sun is a star, being only one of a magnificent
+cluster that forms the Milky Way. We have also seen that there are
+other groups scattered through the length and depth of space. It is
+thus we obtain a notion of the rank which our earth holds in the
+scheme of things celestial.
+
+[Illustration: FIG. 2. GLOBULAR CLUSTER IN THE CENTAUR.]
+
+
+The Rank of the Earth as a Globe in Space.
+
+Let me give an illustration with the view of explaining more fully the
+nature of the relation which the earth bears to the other globes which
+abound through space, and you must allow me to draw a little upon my
+imagination. I shall suppose that the mails of our country extend not
+only over this globe, but that they also communicate with other
+worlds; that postal arrangements exist between Mars and the earth,
+between the sun and Orion--in fact, everywhere throughout the whole
+extent of the universe. We shall consider how our letters are to be
+addressed. Let us take the case of Mr. John Smith, merchant, who lives
+at 1001, Piccadilly; and let us suppose that Mr. John Smith's business
+transactions are of such an extensive nature that they reach not only
+all over this globe, but away throughout space. I shall suppose that
+the firm has a correspondent residing--let us say in the constellation
+of the Great Bear; and when this man of business wants to write to Mr.
+Smith from these remote regions, what address must he put upon the
+letter, so that the Postmaster-General of the universe shall make no
+mistake about its delivery? He will write as follows:--
+
+  MR. JOHN SMITH,
+    1001 Piccadilly,
+      London,
+        England,
+          Europe,
+            Earth,
+              Near the Sun,
+                Milky Way,
+                  The Universe.
+
+Let us now see what the several lines of this address mean. Of course
+we put down the name of Mr. John Smith in the first line, and then we
+will add "1001 Piccadilly" for the second; but as the people in the
+Great Bear are not likely to know where Piccadilly is, we shall add
+"London" underneath. As even London itself cannot be well known
+everywhere, it is better to write "England." This would surely find
+Mr. John Smith from any post-office on this globe. From other globes,
+however, the supreme importance of England may not be so immediately
+recognized, and therefore it is as well to add another line, "Europe."
+This ought to be sufficient, I think, for any post-office in the solar
+system. Europe is big enough to be visible from Mars or Venus, and
+should be known to the post-office people there, just as we know and
+have names for the continents on Mars. But further away there might be
+a little difficulty; from Uranus and Neptune the different regions on
+our earth can never have been distinguished, and therefore we must add
+another line to indicate the particular globe of the solar system
+which contains Europe. Mark Twain tells us that there was always one
+thing in astronomy which specially puzzled him, and that was to know
+how we found out the names of the stars. We are, of course, in
+hopeless ignorance of the name by which this earth is called among
+other intelligent beings elsewhere who can see it. I can only adopt
+the title of "Earth," and therefore I add this line. Now our address
+is so complete that from anywhere in the solar system--from Mercury,
+from Jupiter, or Neptune--there ought to be no mistake about the
+letter finding its way to Mr. John Smith. But from his correspondent
+in the Great Bear this address would be still incomplete; they cannot
+see our earth from there, and even the sun himself only looks like a
+small star--like one, in fact, of thousands of stars elsewhere.
+However, each star can be distinguished, and our sun may, for
+instance, be recognized from the Great Bear by some designation. We
+shall add the line "Near the Sun," and then I think that from this
+constellation, or from any of the other stars around us, the address
+of Mr. John Smith may be regarded as complete. But Mr. Smith's
+correspondence may be still wider. He may have an agent living in the
+cluster of Perseus or on some other objects still fainter and more
+distant; then "Near the Sun" is utterly inadequate as a concluding
+line to the address, for the sun, if it can be seen at all from
+thence, will be only of the significance of an excessively minute
+star, no more to be designated by a special name than are each of the
+several leaves on the trees of a forest. What this distant
+correspondent will be acquainted with is not the earth or the sun but
+only the cluster of stars among which the sun is but a unit. Again we
+use our own name to denote the cluster, and we call it the "Milky
+Way." When we add this line, we have made the address of Mr. John
+Smith as complete as circumstances will permit. I think a letter
+posted to him anywhere ought to reach its destination. To perfect it,
+however, we will finish up with one line more--"The Universe."
+
+
+The Distances of the Stars.
+
+I must now tell you something about the distances of the stars. I
+shall not make the attempt to explain fully how astronomers make such
+measurements, but I will give you some notion of how it is done. You
+may remember I showed you how we found the distance of a globe that
+was hung from the ceiling. The principle of the method for finding the
+distance of a star is somewhat similar, except that we make the two
+observations not from the two ends of a table, not even from opposite
+sides of the earth, but from two opposite points on the earth's orbit,
+which are therefore at a distance of one hundred and eighty-six
+million miles. Imagine that on Midsummer Day, when standing on the
+earth here, I measure with a piece of card the angle between the star
+and the sun. Six months later, on Midwinter Day, when the earth is at
+the opposite point of its orbit, I again measure the angle between the
+same star and the sun, and we can now determine the star's distance by
+making a triangle. I draw a line a foot long, and we will take this
+foot to represent one hundred and eighty-six million miles, the
+distance between the two stations; then placing the cards at the
+corners, I rule the two sides and complete the triangle, and the star
+must be at the remaining corner; then I measure the sides of the
+triangle, and how many feet they contain, and recollecting that each
+foot corresponds to one hundred and eighty-six million miles, we
+discover the distance of the star. If the stars were comparatively
+near us, the process would be a very simple one; but, unfortunately,
+the stars are so extremely far off that this triangle, even with a
+base of only one foot, must have its sides many miles long. Indeed,
+astronomers will tell you that there is no more delicate or
+troublesome work in the whole of their science than that of
+discovering the distance of a star.
+
+In all such measurements we take the distance from the earth to the
+sun as a conveniently long measuring-rod, whereby to express the
+results. The nearest stars are still hundreds of thousands of times as
+far off as the sun. Let us ponder for a little on the vastness of
+these distances. We shall first express them in miles. Taking the
+sun's distance to be ninety-three million miles, then the distance of
+the nearest fixed star is about twenty millions of millions of
+miles--that is to say, we express this by putting down a 2 first, and
+then writing thirteen ciphers after it. It is, no doubt, easy to speak
+of such figures, but it is a very different matter when we endeavor to
+imagine the awful magnitude which such a number indicates. I must try
+to give some illustrations which will enable you to form a notion of
+it. At first I was going to ask you to try and count this number, but
+when I found it would require at least three hundred thousand years,
+counting day and night without stopping, before the task was over, it
+became necessary to adopt some other method.
+
+When on a visit in Lancashire I was once kindly permitted to visit a
+cotton mill, and I learned that the cotton yarn there produced in a
+single day would be long enough to wind round this earth twenty-seven
+times at the equator. It appears that the total production of cotton
+yarn each day in all the mills together would be on the average about
+one hundred and fifty-five million miles. In fact, if they would only
+spin about one-fifth more, we could assert that Great Britain produced
+enough cotton yarn every day to stretch from the earth to the sun and
+back again! It is not hard to find from these figures how long it
+would take for all the mills in Lancashire to produce a piece of yarn
+long enough to reach from our earth to the nearest of the stars. If
+the spinners worked as hard as ever they could for a year, and if all
+the pieces were then tied together, they would extend to only a small
+fraction of the distance; nor if they worked for ten years, or for
+twenty years, would the task be fully accomplished. Indeed, upwards of
+four hundred years would be necessary before enough cotton could be
+grown in America and spun in this country to stretch over a distance
+so enormous. All the spinning that has ever yet been done in the world
+has not formed a long enough thread!
+
+There is another way in which we can form some notion of the immensity
+of these sidereal distances. You will recollect that, when we were
+speaking of Jupiter's moons, I told you of the beautiful discovery
+which their eclipses enabled astronomers to make. It was thus found
+that light travels at the enormous speed of about one hundred and
+eighty-five thousand miles per second. It moves so quickly that within
+a single second a ray would flash two hundred times from London to
+Edinburgh and back again.
+
+We said that a meteor travels one hundred times as swiftly as a
+rifle-bullet; but even this great speed seems almost nothing when
+compared with the speed of light, which is ten thousand times as
+great. Suppose some brilliant outbreak of light were to take place in
+a distant star--an outbreak which would be of such intensity that the
+flash from it would extend far and wide throughout the universe. The
+light would start forth on its voyage with terrific speed. Any
+neighboring star which was at a distance of less than one hundred and
+eighty-five thousand miles would, of course, see the flash within a
+second after it had been produced. More distant bodies would receive
+the intimation after intervals of time proportioned to their
+distances. Thus, if a body were one million miles away, the light
+would reach it in from five to six seconds, while over a distance as
+great as that which separates the earth from the sun the news would be
+carried in about eight minutes. We can calculate how long a time must
+elapse ere the light shall travel over a distance so great as that
+between the star and our earth. You will find that from the nearest of
+the stars the time required for the journey will be over three years.
+Ponder on all that this involves. That outbreak in the star might be
+great enough to be visible here, but we could never become aware of it
+till three years after it had happened. When we are looking at such a
+star to-night we do not see it as it is at present, for the light that
+is at this moment entering our eyes has travelled so far that it has
+been three years on the way. Therefore, when we look at the star now
+we see it as it was three years previously. In fact, if the star were
+to go out altogether, we might still continue to see it twinkling for
+a period of three years longer, because a certain amount of light was
+on its way to us at the moment of extinction, and so long as that
+light keeps arriving here, so long shall we see the star showing as
+brightly as ever. When, therefore, you look at the thousands of stars
+in the sky to-night, there is not one that you see as it is now, but
+as it was years ago.
+
+I have been speaking of the stars that are nearest to us, but there
+are others much farther off. It is true we cannot find the distances
+of these more remote objects with any degree of accuracy, but we can
+convince ourselves how great that distance is by the following
+reasoning. Look at one of the brightest stars. Try to conceive that
+the object was carried away further into the depths of space, until it
+was ten times as far from us as it is at present, it would still
+remain bright enough to be recognized in quite a small telescope; even
+if it were taken to one hundred times its original distance it would
+not have withdrawn from the view of a good telescope; while if it
+retreated one thousand times as far as it was at first it would still
+be a recognizable point in our mightiest instruments. Among the stars
+which we can see with our telescopes, we feel confident there must be
+many from which the light has expended hundreds of years, or even
+thousands of years, on the journey. When, therefore, we look at such
+objects, we see them, not as they are now, but as they were ages ago;
+in fact, a star might have ceased to exist for thousands of years, and
+still be seen by us every night as a twinkling point in our great
+telescopes.
+
+Remembering these facts, you will, I think, look at the heavens with a
+new interest. There is a bright star, Vega, or Alpha Lyræ, a beautiful
+gem, so far off that the light from it which now reaches our eyes
+started before many of my audience were born. Suppose that there are
+astronomers residing on worlds amid the stars, and that they have
+sufficiently powerful telescopes to view this globe, what do you think
+they would observe? They will not see our earth as it is at present;
+they will see it as it was years (and sometimes many years) ago. There
+are stars from which if England could now be seen, the whole of the
+country would be observed at this present moment to be in a great
+state of excitement at a very auspicious event. Distant astronomers
+might notice a great procession in London, and they could watch the
+coronation of a youthful queen amid the enthusiasm of a nation. There
+are other stars still further, from which, if the inhabitants had good
+enough telescopes, they would now see a mighty battle in progress not
+far from Brussels. One splendid army could be beheld hurling itself
+time after time against the immovable ranks of the other. They would
+not, indeed, be able to hear the ever-memorable "Up, Guards, and at
+them!" but there can be no doubt that there are stars so far away that
+the rays of light which started from the earth on the day of the
+battle of Waterloo are only just arriving there. Further off still,
+there are stars from which a bird's-eye view could be taken at this
+very moment of the signing of Magna Charta. There are even stars from
+which England, if it could be seen at all, would now appear, not as
+the great England we know, but as a country covered by dense forests,
+and inhabited by painted savages, who waged incessant war with wild
+beasts that roamed through the island. The geological problems that
+now puzzle us would be quickly solved could we only go far enough into
+space and had we only powerful enough telescopes. We should then be
+able to view our earth through the successive epochs of past
+geological time; we should be actually able to see those great animals
+whose fossil remains are treasured in our museums tramping about over
+the earth's surface, splashing across its swamps, or swimming with
+broad flippers through its oceans. Indeed, if we could view our own
+earth reflected from mirrors in the stars, we might still see Moses
+crossing the Red Sea, or Adam and Eve being expelled from Eden.
+
+So important is the subject of star distance that I am tempted to give
+one more illustration in order to bring before you some conception of
+how vast such distances are. I shall take, as before, the nearest of
+the stars so far as known to us, and I hope to be forgiven for taking
+an illustration of a practical and a commercial kind instead of one
+more purely scientific. I shall suppose that a railway is about to be
+made from London to Alpha Centauri. The length of that railway, of
+course, we have already stated: it is twenty billions of miles. So I
+am now going to ask your attention to the simple question as to the
+fare which it would be reasonable to charge for the journey. We shall
+choose a very cheap scale on which to compute the price of a ticket.
+The parliamentary rate here is, I believe, a penny for every mile. We
+will make our interstellar railway fares much less even than this; we
+shall arrange to travel at the rate of one hundred miles for every
+penny. That, surely, is moderate enough. If the charges were so low
+that the journey from London to Edinburgh only cost fourpence, then
+even the most unreasonable passenger would be surely contented. On
+these terms how much do you think the fare from London to this star
+ought to be? I know of one way in which to make our answer
+intelligible. There is a National Debt with which your fathers are,
+unhappily, only too well acquainted; you will know quite enough about
+it yourselves in those days when you have to pay income tax. This debt
+is so vast that the interest upon it is about sixty thousand pounds a
+day, the whole amount of the National Debt being six hundred and
+thirty-eight millions of pounds.
+
+If you went to the booking-office with the whole of this mighty sum in
+your pocket--but stop a moment; could you carry it in your pocket?
+Certainly not, if it were in sovereigns. You would find that after you
+had as many sovereigns as you could conveniently carry there would
+still be some left--so many, indeed, that it would be necessary to get
+a cart to help you on with the rest. When the cart had as great a load
+of sovereigns as the horse could draw there would be still some more,
+and you would have to get another cart; but ten carts, twenty carts,
+fifty carts, would not be enough. You would want five thousand of
+these before you would be able to move off towards the station with
+your money. When you did get there and asked for a ticket at the rate
+of one hundred miles for a penny, do you think you would get any
+change? No doubt some little time would be required to count the
+money, but when it was counted the clerk would tell you that there was
+not enough--that he must have nearly two hundred millions of pounds
+more.
+
+That will give some notion of the distance of the nearest star, and we
+may multiply it by ten, by one hundred, and even by one thousand, and
+still not attain to the distance of some of the more remote stars that
+the telescope shows us.
+
+On account of the immense distances of the stars we can only perceive
+them to be mere points of light. We can never see a star to be a globe
+with marks on it like the moon, or like one of the planets--in fact,
+the better the telescope the smaller does the star seem, though, of
+course, its brightness is increased with every addition to the
+light-grasping power of the instrument.
+
+
+The Brightness and Color of Stars.
+
+Another point to be noticed is the arrangement of stars in classes,
+according to their lustre. The brightest stars, of which there are
+about twenty, are said to be of the first magnitude. Those just
+inferior to the first magnitude are ranked as the second; and those
+just lower than the second are estimated as the third; and so on. The
+smallest points that your unaided eyes will show you are of about the
+sixth magnitude. Then the telescope will reveal stars still fainter
+and fainter, down to what we term the seventeenth or eighteenth
+magnitudes, or even lower still. The number of stars of each magnitude
+increases very much in the classes of small ones.
+
+Most of the stars are white, but many are of a somewhat ruddy hue.
+There are a few telescopic points which are intensely red, some
+exhibit beautiful golden tints, while others are blue or green.
+
+There are some curious stars which regularly change their brilliancy.
+Let me try to illustrate the nature of these variables. Suppose that
+you were looking at a street gas-lamp from a very long distance, so
+that it seemed a little twinkling light; and suppose that some one was
+preparing to turn the gas-cock up and down. Or, better still, imagine
+a little machine which would act regularly so as to keep the light
+first of all at its full brightness for two days and a half, and then
+gradually turn it down until in three or four hours it declines to a
+feeble glimmer. In this low state the light remains for twenty
+minutes; then during three or four hours the gas is to be slowly
+turned on again until it is full. In this condition the light will
+remain for two days and a half, and then the same series of changes is
+to recommence. This would be a very odd form of gas-lamp. There would
+be periods of two days and a half during which it would remain at its
+full; these would be separated by intervals of about seven hours, when
+the gradual turning down and turning up again would be in progress.
+
+The imaginary gas-lamp is exactly paralleled by a star Algol, in the
+constellation of Perseus (Fig. 3), which goes through the series of
+changes I have indicated. Ordinarily speaking, it is a bright star of
+the second magnitude, and, whatever be the cause, the star performs
+its variations with marvellous uniformity. In fact, Algol has always
+arrested the attention of those who observed the heavens, and in early
+times was looked on as the eye of a demon. There are many other stars
+which also change their brilliancy. Most of them require much longer
+periods than Algol, and sometimes a new star which nobody has ever
+seen before will suddenly kindle into brilliancy. It is now known that
+the bright star Algol is attended by a dark companion. This dark star
+sometimes comes between Algol and the observer and cuts off the light.
+Thus it is that the diminution of brightness is produced.
+
+[Illustration: FIG. 3. PERSEUS AND ITS NEIGHBORING STARS INCLUDING
+ALGOL.]
+
+
+Double Stars.
+
+Whenever you have a chance of looking at the heavens through a
+telescope, you should ask to be shown what is called _a double star_.
+There are many stars in the heavens which present no remarkable
+appearance to the unaided eye, but which a good telescope at once
+shows to be of quite a complex nature. These are what we call double
+stars, in which two quite distinct stars are placed so close together
+that the unaided eye is unable to separate them. Under the magnifying
+power of the telescope, however, they are seen to be distinct. In
+order to give some notion of what these objects are like, I shall
+briefly describe three of them. The first lies in that best known
+constellation, the Great Bear. If you look at his tail, which consists
+of three stars, you will see that near the middle one of the three a
+small star is situated; we call this little star Alcor, but it is the
+brighter one near Alcor to which I specially call your attention. The
+sharpest eye would never suspect that it was composed of two stars
+placed close together. Even a small telescope will, however, show this
+to be the case, and this is the easiest and the first observation that
+a young astronomer should make when beginning to turn a telescope to
+the heavens. Of course you will not imagine that I mean Alcor to be
+the second component of the double star; it is the bright star near
+Alcor which is the double. Here are two marbles, and these marbles are
+fastened an inch apart. You can see them, of course, to be separate;
+but if the pair were moved further and further away, then you would
+soon not be able to distinguish between them, though the actual
+distance between the marbles had not altered. Look at these two wax
+tapers which are now lighted; the little flames are an inch apart. You
+would have to view them from a station a third of a mile away if the
+distance between the two flames were to appear the same as that
+between the two components of this double star. Your eye would never
+be able to discriminate between two lights only an inch apart at so
+great a distance; a telescope would, however, enable you to do so, and
+this is the reason why we have to use telescopes to show us double
+stars.
+
+You might look at that double star year after year throughout the
+course of a long life without finding any appreciable change in the
+relative positions of its components. But we know that there is no
+such thing as rest in the universe; even if you could balance a body
+so as to leave it for a moment at rest, it would not stay there, for
+the simple reason that all the bodies round it in every direction are
+pulling at it, and it is certain that the pull in one direction will
+preponderate, so that move it must. Especially is this true in the
+case of two suns like those forming a double star. Placed
+comparatively near each other they could not remain permanently in
+that position; they must gradually draw together and come into
+collision with an awful crash. There is only one way by which such a
+disaster could be averted. That is by making one of these stars
+revolve around the other just as the earth revolves around the sun, or
+the moon revolves around the earth. Some motion must, therefore, be
+going on in every genuine double star, whether we have been able to
+see that motion or not.
+
+Let us now look at another double star of a different kind. This time
+it is in the constellation of Gemini. The heavenly twins are called
+Castor and Pollux. Of these, Castor is a very beautiful double star,
+consisting of two bright points, a great deal closer together than
+were those in the Great Bear; consequently a better telescope is
+required for the purpose of showing them separately. Castor has been
+watched for many years, and it can be seen that one of these stars is
+slowly revolving around the other; but it takes a very long time,
+amounting to hundreds of years, for a complete circuit to be
+accomplished. This seems very astonishing, but when you remember how
+exceedingly far Castor is, you will perceive that that pair of stars
+which appear so close together that it requires a telescope to show
+them apart must indeed be separated by hundreds of millions of miles.
+Let us try to conceive our own system transformed into a double star.
+If we took our outermost planet--Neptune--and enlarged him a good
+deal, and then heated him sufficiently to make him glow like a sun, he
+would still continue to revolve round our sun at the same distance,
+and thus a double star would be produced. An inhabitant of Castor who
+turned his telescope towards us would be able to see the sun as a
+star. He would not, of course, be able to see the earth, but he might
+see Neptune like another small star close to the sun. If generations
+of astronomers in Castor continued their observations of our system,
+they would find a binary star, of which one component took a century
+and a half to go round the other. Need we then be surprised that when
+we look at Castor we observe movements that seem very slow?
+
+There is often so much diffused light about the bright stars seen in a
+telescope, and so much twinkling in some states of the atmosphere,
+that stars appear to dance about in rather a puzzling fashion,
+especially to one who is not accustomed to astronomical observations.
+I remember hearing how a gentleman once came to visit an observatory.
+The astronomer showed him Castor through a powerful telescope as a
+fine specimen of a double star, and then, by way of improving his
+little lesson, the astronomer mentioned that one of these stars was
+revolving around the other. "Oh, yes," said the visitor, "I saw them
+going round and round in the telescope." He would, however, have had
+to wait for a few centuries with his eye to the instrument before he
+would have been entitled to make this assertion.
+
+Double stars also frequently delight us by giving beautifully
+contrasted colors. I dare say you have often noticed the red and the
+green lights that are used on railways in the signal lamps. Imagine
+one of those red and one of those green lights away far up in the sky
+and placed close together, then you would have some idea of the
+appearance that a colored double star presents, though, perhaps, I
+should add that the hues in the heavenly bodies are not so vividly
+different as are those which our railway people find necessary. There
+is a particularly beautiful double star of this kind in the
+constellation of the Swan. You could make an imitation of it by boring
+two holes, with a red-hot needle, in a piece of card, and then
+covering one of these holes with a small bit of the topaz-colored
+gelatine with which Christmas crackers are made. The other star is to
+be similarly colored with blue gelatine. A slide made on this
+principle placed in the lantern gives a very good representation of
+these two stars on the screen. There are many other colored doubles
+besides this one; and, indeed, it is noteworthy that we hardly ever
+find a blue or a green star by itself in the sky; it is always as a
+member of one of these pairs.
+
+
+How We Find What the Stars are Made of.
+
+Here is a piece of stone. If I wanted to know what it was composed of,
+I should ask a chemist to tell me. He would take it into his
+laboratory, and first crush it into powder, and then, with his test
+tubes, and with the liquids which his bottles contain, and his
+weighing scales, and other apparatus, he would tell all about it;
+there is so much of this, and so much of that, and plenty of this, and
+none at all of that. But now, suppose you ask this chemist to tell you
+what the sun is made of, or one of the stars. Of course, you have not
+a sample of it to give him; how, then, can he possibly find out
+anything about it? Well, he can tell you something, and this is the
+wonderful discovery that I want to explain to you. We now put down the
+gas, and I kindle a brilliant red light. Perhaps some of those whom I
+see before me have occasionally ventured on the somewhat dangerous
+practice of making fire-works. If there is any boy here who has ever
+constructed sky-rockets, and put the little balls into the top which
+are to burn with such vivid colors when the explosion takes place, he
+will know that the substance which tinged that fire red must have been
+strontium. He will recognize it by the color; because strontium gives
+a red light which nothing else will give. Here are some of these
+lightning papers, as they are called; they are very pretty and very
+harmless; and these, too, give brilliant red flashes as I throw them.
+The red tint has, no doubt, been produced by strontium also. You see
+we recognized the substance simply by the color of the light it
+produced when burning.
+
+Perhaps some of you have tried to make a ghost at Christmas by
+dressing up in a sheet, and bearing in your hand a ladle blazing with
+a mixture of common salt and spirits of wine, the effect produced
+being a most ghastly one. Some mammas will hardly thank me for this
+suggestion, unless I add that the ghost must walk about cautiously,
+for otherwise the blazing spirit would be very apt to produce
+conflagrations of a kind more extensive than those intended. However,
+by the kindness of Professor Dewar, I am enabled to show the
+phenomenon on a splendid scale, and also free from all danger. I
+kindle a vivid flame of an intensely yellow color, which I think the
+ladies will unanimously agree is not at all becoming to their
+complexions, while the pretty dresses have lost their variety of
+colors. Here is a nice bouquet, and yet you can hardly distinguish the
+green of the leaves from the brilliant colors of the flowers, except
+by trifling differences of shade. Expose to this light a number of
+pieces of variously colored ribbon, pink and red and green and blue,
+and their beauty is gone; and yet we are told that this yellow is a
+perfectly pure color; in fact, the purest color that can be produced.
+I think we have to be thankful that the light which our good sun sends
+us does not possess purity of that description. There is one substance
+which will produce that yellow light; it is a curious metal called
+sodium--a metal so soft that you can cut it with a knife, and so light
+that it will float on water; while, still more strange, it actually
+takes fire the moment it is dropped on the water. It is only in a
+chemical laboratory that you will be likely to meet with the actual
+metallic sodium, yet in other forms the substance is one of the most
+abundant in nature. Indeed, common salt is nothing but sodium closely
+united with a most poisonous gas, a few respirations of which would
+kill you. But this strange metal and this noxious gas, when united,
+become simply the salt for our eggs at breakfast. This pure yellow
+light, wherever it is seen, either in the flame of spirits of wine
+mixed with salt or in that great blaze at which we have been looking,
+is characteristic of sodium. Wherever you see that particular kind of
+light, you know that sodium must have been present in the body from
+which it came.
+
+We have accordingly learned to recognize two substances, namely,
+strontium and sodium, by the different lights which they give out when
+burning. To these two metals we may add a third. Here is a strip of
+white metallic ribbon. It is called magnesium. It seems like a bit of
+tin at the first glance, but indeed it is a very different substance
+from tin; for, look, when I hold it in the spirit-lamp, the strip of
+metal immediately takes fire, and burns with a white light so dazzling
+that it pales the gas-flames to insignificance. There is no other
+substance which will, when kindled, give that particular kind of light
+which we see from magnesium. I can recommend this little experiment as
+quite suitable for trying at home; you can buy a bit of magnesium
+ribbon for a trifle at the opticians; it cannot explode or do any
+harm, nor will you get into any trouble with the authorities provided
+you hold it when burning over a tray or a newspaper, so as to prevent
+the white ashes from falling on the carpet.
+
+There are, in nature, a number of simple bodies called elements.
+Every one of these, when ignited under suitable conditions, emits a
+light which belongs to it alone, and by which it can be distinguished
+from every other substance. I do not say that we can try the
+experiments in the simple way I have here indicated. Many of the
+materials will yield light which will require to be studied by much
+more elaborate artifices than those which have sufficed for us. But
+you will see that the method affords a means of finding out the actual
+substances present in the sun or in the stars. There is a practical
+difficulty in the fact that each of the heavenly bodies contains a
+number of different elements; so that in the light it sends us the
+hues arising from distinct substances are blended into one beam. The
+first thing to be done is to get some way of splitting up a beam of
+light, so as to discover the components of which it is made. You might
+have a skein of silks of different hues tangled together, and this
+would be like the sunbeam as we receive it in its unsorted condition.
+How shall we untangle the light from the sun or a star? I will show
+you by a simple experiment. Here is a beam from the electric light;
+beautifully white and bright, is it not? It looks so pure and simple,
+but yet that beam is composed of all sorts of colors mingled together,
+in such proportions as to form white light. I take a wedge-shaped
+piece of glass called a prism, and when I introduce it into the course
+of the beam, you see the transformation that has taken place (Fig. 4).
+Instead of the white light you have now all the colors of the
+rainbow--red, orange, yellow, green, blue, indigo, violet, marked by
+their initial letters in the figure. These colors are very beautiful,
+but they are transient, for the moment we take away the prism they
+all unite again to form white light. You see what the prism has done;
+it has bent all the light in passing through it; but it is more
+effective in bending the blue than the red, and consequently the blue
+is carried away much further than the red. Such is the way in which we
+study the composition of a heavenly body. We take a beam of its light,
+we pass it through a prism, and immediately it is separated into its
+components; then we compare what we find with the lights given by the
+different elements, and thus we are enabled to discover the substances
+which exist in the distant object whose light we have examined. I do
+not mean to say that the method is a simple one; all I am endeavoring
+to show is a general outline of the way in which we have discovered
+the materials present in the stars. The instrument that is employed
+for this purpose is called the spectroscope. And perhaps you may
+remember that name by these lines, which I have heard from an
+astronomical friend:--
+
+  "Twinkle, twinkle, little star,
+  Now we find out what you are,
+  When unto the midnight sky,
+  We the spectroscope apply."
+
+[Illustration: FIG. 4. HOW A RAY OF LIGHT IS SPLIT UP.]
+
+I am sure it will interest everybody to know that the elements which
+the stars contain are not altogether different from those of which the
+earth is made. It is true there may be substances in the stars of
+which we know nothing here; but it is certain that many of the most
+common elements on the earth are present in the most distant bodies. I
+shall only mention one, the metal iron. That useful substance has been
+found in some of the stars which lie at almost incalculable distances
+from the earth.
+
+
+The Nebulæ.
+
+In drawing towards the close of these lectures I must say a few words
+about some dim and mysterious objects to which we have not yet
+alluded. They are what are called nebulæ, or little clouds; and in
+one sense they are justly called little, for each of them occupies but
+a very small spot in the sky as compared with that which would be
+filled by an ordinary cloud in our air. The nebulæ are, however,
+objects of the most stupendous proportions. Were our earth and
+thousands of millions of bodies quite as big all put together, they
+would not be nearly so great as one of these nebulæ. Astronomers
+reckon up the various nebulæ by thousands, but I must add that most of
+them are apparently faint and uninteresting. A nebula is sometimes
+liable to be mistaken for a comet. The comet is, as I have already
+explained, at once distinguished by the fact that it is moving and
+changing its appearance from hour to hour, while scores of years
+elapse without changes in the aspect or position of a nebula. The most
+powerful telescopes are employed in observing these faint objects. I
+take this opportunity of showing a picture of an instrument suitable
+for such observations. It is the great reflector of the Paris
+Observatory (Fig. 5).
+
+[Illustration: FIG. 5. A GREAT REFLECTING TELESCOPE.]
+
+[Illustration: FIG. 6. THE RING NEBULA IN LYRA, UNDER DIFFERENT
+TELESCOPIC POWERS.]
+
+There are such multitudes of nebulæ that I can only show a few of the
+more remarkable kinds. In Fig. 6 will be seen pictures of a curious
+object in the constellation of Lyra seen under different telescopic
+powers. This is a gigantic ring of luminous gas. To judge of the size
+of this ring let us suppose that a railway were laid across it, and
+the train you entered at one side was not to stop until it reached the
+other side, how long do you think this journey would require? I
+recollect some time ago a picture in _Punch_ which showed a train
+about to start from London to Brighton, and the guard walking up and
+down announcing to the passengers the alarming fact that "this train
+stops nowhere." An old gentleman was seen vainly gesticulating out of
+the window and imploring to be let out ere the frightful journey was
+commenced. In the nebular railway the passengers would almost require
+such a warning.
+
+Let the train start at a speed of a mile a minute, you would think,
+surely, that it must soon cross the ring. But the minutes pass, an
+hour has elapsed; so the distance must be sixty miles at all events.
+The hours creep on into days, the days advance into years, and still
+the train goes on. The years would lengthen out into centuries, and
+even when the train had been rushing on for a thousand years with an
+unabated speed of a mile a minute, the journey would certainly not
+have been completed. Nor do I venture to say what ages must elapse ere
+the terminus at the other side of the ring nebula would be reached.
+
+A cluster of stars viewed in a small telescope will often seem like a
+nebula, for the rays of the stars become blended. A powerful telescope
+will, however, dispel the illusion and reveal the separate stars. It
+was, therefore, thought that all the nebulæ might be merely clusters
+so exceedingly remote that our mightiest instruments failed to resolve
+them into stars. But this is now known not to be the case. Many of
+these objects are really masses of glowing gas; such are, for
+instance, the ring nebulæ, of which I have just spoken, and the form
+of which I can simulate by a pretty experiment.
+
+We take a large box with a round hole cut in one face, and a canvas
+back at the opposite side. I first fill this box with smoke, and there
+are different ways of doing so. Burning brown paper does not answer
+well, because the supply of smoke is too irregular and the paper
+itself is apt to blaze. A little bit of phosphorus set on fire yields
+copious smoke, but it would be apt to make people cough, and, besides,
+phosphorus is a dangerous thing to handle incautiously, and I do not
+want to suggest anything which might be productive of disaster if the
+experiment was repeated at home. A little wisp of hay, slightly damped
+and lighted, will safely yield a sufficient supply, and you need not
+have an elaborate box like this; any kind of old packing-case, or even
+a bandbox with a duster stretched across its open top and a round hole
+cut in the bottom, will answer capitally. While I have been speaking,
+my assistant has kindly filled this box with smoke, and in order to
+have a sufficient supply, and one which shall be as little
+disagreeable as possible, he has mixed together the fumes of
+hydrochloric acid and ammonia from two retorts shown in Fig. 7. A
+still simpler way of doing the same thing is to put a little common
+salt in a saucer and pour over it a little oil of vitriol; this is put
+into the box, and over the floor of the box common smelling-salts is
+to be scattered. You see there are dense volumes of white smoke
+escaping from every corner of the box. I uncover the opening and give
+a push to the canvas, and you see a beautiful ring flying across the
+room; another ring and another follows. If you were near enough to
+feel the ring, you would experience a little puff of wind; I can show
+this by blowing out a candle which is at the other end of the table.
+These rings are made by the air which goes into a sort of eddy as it
+passes through the hole. All the smoke does is to render the air
+visible. The smoke-ring is indeed quite elastic. If we send a second
+ring hurriedly after the first, we can produce a collision, and you
+see each of the two rings remains unbroken, though both are quivering
+from the effects of the blow. They are beautifully shown along the
+beam of the electric lamp, or, better still, along a sunbeam.
+
+[Illustration: FIG. 7. HOW TO MAKE THE SMOKE RINGS.]
+
+We can make many experiments with smoke-rings. Here, for instance, I
+take an empty box, so far as smoke is concerned, but air-rings can be
+driven forth from it, though you cannot see them, but you can feel
+them even at the other side of the room, and they will, as you see,
+blow out a candle. I can also shoot invisible air-rings at a column of
+smoke, and when the missile strikes the smoke it produces a little
+commotion and emerges on the other side, carrying with it enough of
+the smoke to render itself visible, while the solid black looking ring
+of air is seen in the interior. Still more striking is another way of
+producing these rings, for I charge this box with ammonia, and the
+rings from it you cannot see. There is a column of the vapor of
+hydrochloric acid, that also you cannot see; but when the visible ring
+enters the invisible column, then a sudden union takes place between
+the vapor of the ammonia and the vapor of the hydrochloric acid; the
+result is a solid white substance in extremely fine dust which renders
+the ring instantly visible.
+
+
+What the Nebulæ are made of.
+
+There is a fundamental difference between the illumination of these
+little rings that I have shown you and the great rings in the heavens.
+I had to illuminate our smoke with the help of the electric light,
+for, unless I had done so, you would not have been able to see them.
+This white substance formed by the union of ammonia and hydrochloric
+acid has, of course, no more light of its own than a piece of chalk;
+it requires other light falling upon it to make it visible. Were the
+ring nebula in Lyra composed of this material, we could not see it.
+The sunlight which illuminates the planets might, of course, light up
+such an object as the ring, if it wrere comparatively near us; but
+Lyra is at such a stupendous distance that any light which the sun
+could send out there would be just as feeble as the light we receive
+from a fixed star. Should we be able to show our smoke-rings, for
+instance, if, instead of having the electric light, I merely cut a
+hole in the ceiling and allowed the feeble twinkle of a star in the
+Great Bear to shine through? In a similar way the sunbeams would be
+utterly powerless to effect any illumination of objects in these
+stellar distances. If the sun were to be extinguished altogether, the
+calamity would no doubt be a very dire one so far as we are concerned,
+but the effect on the other celestial bodies (moon and planets
+excepted) would be of the slightest possible description. All the
+stars of heaven would continue to shine as before. Not a point in one
+of the constellations wrould be altered, not a variation in the
+brightness, not a change in the hue of any star could be noticed. The
+thousands of nebulæ and clusters would be absolutely unaltered; in
+fact, the total extinction of the sun would be hardly remarked in the
+newspapers published in the Pleiades or in Orion. There might possibly
+be a little line somewhere in an odd corner to the effect "Mr.
+So-and-So, our well-known astronomer, has noticed that a tiny star,
+inconspicuous to the eye, and absolutely of no importance whatever,
+has now become invisible."
+
+If, therefore, it be not the sun which lights up this nebula, where
+else can be the source of its illumination? There can be no other star
+in the neighborhood adequate to the purpose, for, of course, such an
+object would be brilliant to us if it were large enough and bright
+enough to impart sufficient illumination to the nebula. It would be
+absurd to say that you could see a man's face by the light of a candle
+while the candle itself was too faint or too distant to be visible.
+The actual facts are, of course, the other way; the candle might be
+visible, when it was impossible to discern the face which it lighted.
+
+Hence we learn that the ring nebula must shine by some light of its
+own, and now we have to consider how it can be possible for such
+material to be self-luminous. The light of a nebula does not seem to
+be like flame; it can, perhaps, be better represented by the pretty
+electrical experiment with Geissler's tubes. These are glass vessels
+of various shapes, and they are all very nearly empty, as you will
+understand when I tell you the way in which they have been prepared. A
+little gas was allowed into each tube, and then almost all the gas was
+taken out again, so that only a mere trace was left. I pass a current
+of electricity through these tubes, and now you see they are glowing
+with beautiful colors. The different gases give out lights of
+different hues, and the optician has exerted his skill so as to make
+the effect as beautiful as possible. The electricity, in passing
+through these tubes, heats the gas which they contain, and makes it
+glow; and just as this gas can, when heated sufficiently, give out
+light, so does the great nebula, which is a mass of gas poised in
+space, become visible in virtue of the heat which it contains.
+
+We are not left quite in doubt as to the constitution of these gaseous
+nebulæ, for we can submit their light to the prism in the way I
+explained when we were speaking of the stars. Distant though that ring
+in Lyra may be, it is interesting to learn that the ingredients from
+which it is made are not entirely different from substances we know on
+our earth. The water in this glass, and every drop of water, is formed
+by the union of two gases, of which one is hydrogen. This is an
+extremely light material, as you see by a little balloon which ascends
+so prettily when filled with it. Hydrogen also burns very readily,
+though the flame is almost invisible. When I blow a jet of oxygen
+through the hydrogen, I produce a little flame with a very intense
+heat. For instance, I hold a steel pen in the flame, and it glows and
+sputters, and falls down in white-hot drops. It is needless to say
+that, as a constituent of water, hydrogen is one of the most important
+elements on this earth. It is, therefore, of interest to learn that
+hydrogen in some form or other is a constituent of the most distant
+objects in space that the telescope has revealed.
+
+
+Photographing the Nebulæ.
+
+[Illustration: FIG. 8. THE PLEIADES.]
+
+Of late years we have learned a great deal about nebulæ, by the help
+which photography has given to us. Look at this group of stars which
+constitutes that beautiful little configuration known as the Pleiades
+(Fig. 8). It looks like a miniature representation of the Great Bear;
+in fact, it would be far more appropriate to call the Pleiades the
+Little Bear than to apply that title to another quite different
+constellation, as has unfortunately been done. The Pleiades form a
+group containing six or seven stars visible to the ordinary eye,
+though persons endowed with exceptionally good vision can usually see
+a few more. In an opera-glass the Pleiades becomes a beautiful
+spectacle, though in a large telescope the stars appear too far apart
+to make a really effective cluster. When Mr. Roberts took a photograph
+of the Pleiades he placed a highly sensitive plate in his telescope,
+and on that plate the Pleiades engraved their picture with their own
+light. He left the plate exposed for hours, and on developing it not
+only were the stars seen, but there were also patches of faint light
+due to the presence of nebulæ. It could not be said that the objects
+on the plate were fallacious, for another photograph was taken, when
+the same appearances were reproduced.
+
+When we look at that pretty group of stars which has attracted
+admiration during all time, we are to think that some of those stars
+are merely the bright points in a vast nebula, invisible to our
+unaided eyes or even to our mighty telescopes, though capable of
+recording its trace on the photographic plate. Does not this give us a
+greatly increased notion of the extent of the universe, when we
+reflect that by photography we are enabled to see much which the
+mightiest of telescopes had previously failed to disclose?
+
+Of all the nebulæ, numbering some thousands, there is but a single one
+which can be seen without a telescope. It is in the constellation of
+Andromeda, and on a clear dark night can just be seen with the unaided
+eye as a faint stain of light on the sky. It has happened before now
+that persons noticing this nebula for the first time have thought they
+had discovered a comet. I would like you to try and find out this
+object for yourselves.
+
+If you look at it with an opera-glass it appears to be distinctly
+elongated. You can see more of its structure when you view it in
+larger instruments, but its nature was never made clear until some
+beautiful photographs were taken by Mr. Roberts (Fig. 9).
+Unfortunately, the nebula in Andromeda has not been placed in the best
+position for its portrait from our point of view. It seems as if it
+were a rather flat-shaped object, turned nearly edgewise towards us.
+To look at the pattern on a plate, you would naturally hold the plate
+so as to be able to look at it squarely. The pattern would not be seen
+well if the plate were so tilted that its edge was turned towards you.
+That seems to be nearly the way in which we are forced to view the
+nebula in Andromeda. We can trace in the photograph some divisions
+extending entirely round the nebula, showing that it seems to be
+formed of a series of rings; and there are some outlying portions
+which form part of the same system. Truly this is a marvellous object.
+It is impossible for us to form any conception of the true dimensions
+of this gigantic nebula; it is so far off that we have never yet been
+able to determine its distance. Indeed, I may take this opportunity of
+remarking that no astronomer has yet succeeded in ascertaining the
+distance of any nebula. Everything, however, points to the conclusion
+that they are at least as far as the stars.
+
+[Illustration: FIG. 9. THE GREAT NEBULA IN ANDROMEDA.]
+
+It is almost impossible to apply the methods which we use in finding
+the distance of a star to the discovery of the distance of the
+nebulæ. These flimsy bodies are usually too ill-defined to admit of
+being measured with the precision and delicacy required for the
+determination of distance. The measurements necessary for this purpose
+can only be made from one star-like point to another similar point. If
+we could choose a star in the nebula and determine its distance, then
+of course, we have the distance of the nebula itself; but the
+difficulty is that we have, in general, no means of knowing whether
+the star does actually lie in the object. It may, for anything we can
+tell, lie billions of miles nearer to us, or billions of miles further
+off, and by merely happening to lie in the line of sight, appear to
+glimmer in the nebula itself.
+
+If we have any assurance that the star is surrounded by a mass of this
+glowing vapor, then it may be possible to measure that nebula's
+distance. It will occasionally happen that grounds can be found for
+believing that a star which appears to be in the glowing gas does
+veritably lie therein, and is not merely seen in the same direction.
+There are hundreds of stars visible in a good drawing or a good
+photograph of the famous object in Andromeda, and doubtless large
+numbers of these are merely stars which happen to lie in the same line
+of sight. The peculiar circumstances attending the history of one star
+seem, however, to warrant us in making the assumption that it was
+certainly in the nebula. The history of this star is a remarkable one.
+It suddenly kindled from invisibility into brilliancy. How is a change
+so rapid in the lustre of a star to be accounted for? In a few days
+its brightness had undergone an extraordinary increase. Of course,
+this does not tell us for certain that the star lay in the glowing
+gas; but the most rational explanation that I have heard offered of
+this occurrence is that due, I believe, to my friend Mr. Monck. He has
+suggested that the sudden outbreak in brilliancy might be accounted
+for on the same principles as those by which we explain the ignition
+of meteors in our atmosphere. If a dark star, moving along with
+terrific speed through space, were suddenly to plunge into a dense
+region of the nebula, heat and light must be evolved in sufficient
+abundance to transform the star into a brilliant object. If,
+therefore, we knew the distance of this star at the time it was in
+Andromeda, we should, of course, learn the distance of that
+interesting object. This has been attempted, and it has thus been
+proved that the Great Nebula must be very much further from us than is
+that star of whose distance I attempted some time ago to give you a
+notion.
+
+We thus realize the enormous size of the Great Nebula. It appears that
+if, on a map of this object, we were to lay down, accurately to scale,
+a map of the solar system, putting the sun in the centre and all the
+planets around their true proportions out to the boundary traced by
+Neptune, this area, vast though it is, would be a mere speck on the
+drawing of the object. Our system would have to be enormously bigger
+before it sufficed to cover anything like the area of the sky included
+in one of these great objects. Here is a sketch of a nebula, Fig. 10,
+and near I have marked a dot, which is to indicate our solar system.
+We may feel confident that the Great Nebula is at the very least as
+mighty as this proportion would indicate.
+
+[Illustration: FIG. 10. THE SOLAR SYSTEM AS COMPARED WITH A GREAT
+NEBULA.]
+
+
+
+
+RAIN AND SNOW
+
+(FROM THE FORMS OF WATER.)
+
+BY JOHN TYNDALL.
+
+
+Oceanic Distillation.
+
+[Illustration: SNOW CRYSTALS.]
+
+At the equator, and within certain limits north and south of it, the
+sun at certain periods of the year is directly overhead at noon. These
+limits are called the Tropics of Cancer and of Capricorn. Upon the
+belt comprised between these two circles the sun's rays fall with
+their mightiest power; for here they shoot directly downwards, and
+heat both earth and sea more than when they strike slantingly.
+
+When the vertical sunbeams strike the land they heat it, and the air
+in contact with the hot soil becomes heated in turn. But when heated
+the air expands, and when it expands it becomes lighter. This lighter
+air rises, like wood plunged into water, through the heavier air
+overhead.
+
+When the sunbeams fall upon the sea the water is warmed, though not so
+much as the land. The warmed water expands, becomes thereby lighter,
+and therefore continues to float upon the top. This upper layer of
+water warms to some extent the air in contact with it, but it also
+sends up a quantity of aqueous vapor, which being far lighter than
+air, helps the latter to rise. Thus both from the land and from the
+sea we have ascending currents established by the action of the sun.
+
+When they reach a certain elevation in the atmosphere, these currents
+divide and flow, part towards the north and part towards the south;
+while from the north and the south a flow of heavier and colder air
+sets in to supply the place of the ascending warm air.
+
+Incessant circulation is thus established in the atmosphere. The
+equatorial air and vapor flow above towards the north and south poles,
+while the polar air flows below towards the equator. The two currents
+of air thus established are called the upper and the lower trade
+winds.
+
+But before the air returns from the poles great changes have occurred.
+For the air as it quitted the equatorial regions was laden with
+aqueous vapor, which could not subsist in the cold polar regions. It
+is there precipitated, falling sometimes as rain, or more commonly as
+snow. The land near the pole is covered with this snow, which gives
+birth to vast glaciers.
+
+It is necessary that you should have a perfectly clear view of this
+process, for great mistakes have been made regarding the manner in
+which glaciers are related to the heat of the sun.
+
+It was supposed that if the sun's heat were diminished, greater
+glaciers than those now existing would be produced. But the lessening
+of the sun's heat would infallibly diminish the quantity of aqueous
+vapor, and thus cut off the glaciers at their source. A brief
+illustration will complete your knowledge here.
+
+In the process of ordinary distillation, the liquid to be distilled is
+heated and converted into vapor in one vessel, and chilled and
+reconverted into liquid in another. What has just been stated renders
+it plain that the earth and its atmosphere constitute a vast
+distilling apparatus in which the equatorial ocean plays the part of
+the boiler, and the chill regions of the poles the part of the
+condenser. In this process of distillation _heat_ plays quite as
+necessary a part as _cold_, and before Bishop Heber could speak of
+"Greenland's icy mountains," the equatorial ocean had to be warmed by
+the sun. We shall have more to say upon this question afterwards.
+
+The heating of the tropical air by the sun is _indirect_. The solar
+beams have scarcely any power to heat the air through which they pass;
+but they heat the land and ocean, and these communicate their heat to
+the air in contact with them. The air and vapor start upwards charged
+with the heat thus communicated.
+
+
+Tropical Rains.
+
+But long before the air and vapor from the equator reach the poles,
+precipitation occurs. Wherever a humid warm wind mixes with a cold dry
+one, rain falls. Indeed the heaviest rains occur at those places where
+the sun is vertically overhead. We must enquire a little more closely
+into their origin.
+
+Fill a bladder about two-thirds full of air at the sea level, and take
+it to the summit of Mount Blanc. As you ascend, the bladder becomes
+more and more distended; at the top of the mountain it is fully
+distended, and has evidently to bear a pressure from within. Returning
+to the sea level you find that the tightness disappears, the bladder
+finally appearing as flaccid as at first.
+
+The reason is plain. At the sea level the air within the bladder has
+to bear the pressure of the whole atmosphere, being thereby squeezed
+into a comparatively small volume. In ascending the mountain, you
+leave more and more of the atmosphere behind; the pressure becomes
+less and less, and by its expansive force the air within the bladder
+swells as the outside pressure is diminished. At the top of the
+mountain the expansion is quite sufficient to render the bladder
+tight, the pressure within being then actually greater than the
+pressure without. By means of an air-pump we can show the expansion of
+a balloon partly filled with air, when the external pressure has been
+in part removed.
+
+But why do I dwell upon this? Simply to make plain to you that the
+_unconfined air_, heated at the earth's surface, and ascending by its
+lightness, must expand more and more the higher it rises in the
+atmosphere.
+
+And now I have to introduce to you a new fact, towards the statement
+of which I have been working for some time. It is this: _The ascending
+air is chilled by its expansion_. Indeed this chilling is one source
+of the coldness of the higher atmospheric regions. And now fix your
+eye upon those mixed currents of air and aqueous vapor which rise from
+the warm tropical ocean. They start with plenty of heat to preserve
+the vapor as vapor; but as they rise they come into regions already
+chilled, and they are still further chilled by their own expansion.
+The consequence might be foreseen. The load of vapor is in great part
+precipitated, dense clouds are formed, their particles coalesce to
+rain-drops, which descend daily in gushes so profuse that the word
+"torrential" is used to express the copiousness of the rainfall. I
+could show you this chilling by expansion, and also the consequent
+precipitation of clouds.
+
+Thus long before the air from the equator reaches the poles its vapor
+is in great part removed from it, having redescended to the earth as
+rain. Still a good quantity of the vapor is carried forward, which
+yields hail, rain, and snow in northern and southern lands.
+
+
+Mountain Condensers.
+
+To complete our view of the process of atmospheric precipitation we
+must take into account the action of mountains. Imagine a south-west
+wind blowing across the Atlantic towards Ireland. In its passage it
+charges itself with aqueous vapor. In the south of Ireland it
+encounters the mountains of Kerry: the highest of these is
+Magillicuddy's Reeks, near Killarney. Now the lowest stratum of this
+Atlantic wind is that which is most fully charged with vapor. When it
+encounters the base of the Kerry Mountains it is tilted up and flows
+bodily over them. Its load of vapor is therefore carried to a height,
+it expands on reaching the height, it is chilled in consequence of
+the expansion, and comes down in copious showers of rain. From this,
+in fact, arises the luxuriant vegetation of Killarney; to this,
+indeed, the lakes owe their water supply. The cold crests of the
+mountains also aid in the work of condensation.
+
+Note the consequence. There is a town called Cahirciveen to the
+south-west of Magillicuddy's Reeks, at which observations of the
+rainfall have been made, and a good distance farther to the
+north-east, right in the course of the south-west wind there is
+another town, called Portarlington, at which observations of rainfall
+have also been made. But before the wind reaches the latter station it
+has passed over the mountains of Kerry and left a great portion of its
+moisture behind it. What is the result? At Cahirciveen, as shown by
+Dr. Lloyd, the rainfall amounts to fifty-nine inches in a year, while
+at Portarlington it is only twenty-one inches.
+
+Again, you may sometimes descend from the Alps when the fall of rain
+and snow is heavy and incessant, into Italy, and find the sky over the
+plains of Lombardy blue and cloudless, the wind at the same time
+_blowing over the plain towards the Alps_. Below the wind is hot
+enough to keep its vapor in a perfectly transparent state; but it
+meets the mountains, is tilted up, expanded, and chilled. The cold of
+the higher summits also helps the chill. The consequence is that the
+vapor is precipitated as rain or snow, thus producing bad weather upon
+the heights, while the plains below, flooded with the same air, enjoy
+the aspect of the unclouded summer sun. Clouds blowing _from_ the
+Alps are also sometimes dissolved over the plains of Lombardy.
+
+In connection with the formation of clouds by mountains, one
+particularly instructive effect may be here noticed. You frequently
+see a streamer of cloud many hundred yards in length drawn out from an
+Alpine peak. Its steadiness appears perfect, though a strong wind may
+be blowing at the same time over the mountain head. Why is the cloud
+not blown away? It _is_ blown away; its permanence is only apparent.
+At one end it is incessantly dissolved; at the other end it is
+incessantly renewed: supply and consumption being thus equalized, the
+cloud appears as changeless as the mountain to which it seems to
+cling. When the red sun of the evening shines upon these
+cloud-streamers they resemble vast torches with their flames blown
+through the air.
+
+Architecture of Snow.
+
+We now resemble persons who have climbed a difficult peak, and thereby
+earned the enjoyment of a wide prospect. Having made ourselves masters
+of the conditions necessary to the production of mountain snow, we are
+able to take a comprehensive and intelligent view of the phenomena of
+glaciers.
+
+[Illustration: SNOW CRYSTALS.]
+
+A few words are still necessary as to the formation of snow. The
+molecules and atoms of all substances, when allowed free play, build
+themselves into definite and, for the most part, beautiful forms
+called crystals. Iron, copper, gold, silver, lead, sulphur, when
+melted and permitted to cool gradually, all show this crystallizing
+power. The metal bismuth shows it in a particularly striking manner,
+and when properly fused and solidified, self-built crystals of great
+size and beauty are formed of this metal.
+
+[Illustration: SNOW-STAR.]
+
+[Illustration: SNOW-STAR.]
+
+If you dissolve salt-petre in water, and allow the solution to
+evaporate slowly, you may obtain large crystals, for no portion of the
+salt is converted into vapor. The water of our atmosphere is fresh
+though it is derived from the salt sea. Sugar dissolved in water, and
+permitted to evaporate, yields crystals of sugar-candy. Alum readily
+crystallizes in the same way. Flints dissolved, as they sometimes are
+in nature, and permitted to crystallize, yield the prisms and pyramids
+of rock crystal. Chalk dissolved and crystallized yields Iceland spar.
+The diamond is crystallized carbon. All our precious stones, the
+ruby, sapphire, beryl, topaz, emerald, are all examples of this
+crystallizing power.
+
+[Illustration: SNOW-STAR.]
+
+You have heard of the force of gravitation, and you know that it
+consists of an attraction of every particle of matter for every other
+particle. You know that planets and moons are held in their orbits by
+this attraction. But gravitation is a very simple affair compared to
+the force, or rather forces, of crystallization. For here the ultimate
+particles of matter, inconceivably small as they are, show themselves
+possessed of attractive and repellent poles, by the mutual action of
+which the shape and structure of the crystal are determined. In the
+solid condition the attracting poles are rigidly locked together; but
+if sufficient heat be applied the bond of union is dissolved, and in
+the state of fusion the poles are pushed so far asunder as to be
+practically out of each other's range. The natural tendency of the
+molecules to build themselves together is thus neutralized.
+
+This is the case with water, which as a liquid is to all appearance
+formless. When sufficiently cooled the molecules are brought within
+the play of the crystallizing force, and they then arrange themselves
+in forms of indescribable beauty. When snow is produced in calm air,
+the icy particles build themselves into beautiful stellar shapes, each
+star possessing six rays. There is no deviation from this type, though
+in other respects the appearances of the snow-stars are infinitely
+various. In the polar regions these exquisite forms were observed by
+Dr. Scoresby, who gave numerous drawings of them. I have observed them
+in mid-winter filling the air, and loading the slopes of the Alps. But
+in England they are also to be seen, and no words of mine could convey
+so vivid an impression of their beauty as the annexed drawings of a
+few of them, executed at Greenwich by Mr. Glaisher.
+
+[Illustration: SNOW-STAR.]
+
+It is worth pausing to think what wonderful work is going on in the
+atmosphere during the formation and descent of every snow-shower; what
+building power is brought into play! and how imperfect seem the
+productions of human minds and hands when compared with those formed
+by the blind forces of nature!
+
+But who ventures to call the forces of nature blind? In reality, when
+we speak thus we are describing our own condition. The blindness is
+ours; and what we really ought to say, and to confess, is that our
+powers are absolutely unable to comprehend either the origin or the
+end of the operations of nature.
+
+But while we thus acknowledge our limits, there is also reason for
+wonder at the extent to which science has mastered the system of
+nature. From age to age, and from generation to generation, fact has
+been added to fact, and law to law, the true method and order of the
+Universe being thereby more and more revealed. In doing this science
+has encountered and overthrown various forms of superstition and
+deceit, of credulity and imposture. But the world continually produces
+weak persons and wicked persons; and as long as they continue to exist
+side by side, as they do in this our day, very debasing beliefs will
+also continue to infest the world.
+
+
+Atomic Poles.
+
+"What did I mean when, a few moments ago I spoke of attracting and
+repellent poles?" Let me try to answer this question. You know that
+astronomers and geographers speak of the earth's poles, and you have
+also heard of magnetic poles, the poles of a magnet being the points
+at which the attraction and repulsion of the magnet are as it were
+concentrated.
+
+Every magnet possesses two such poles; and if iron filings be
+scattered over a magnet, each particle becomes also endowed with two
+poles. Suppose such particles devoid of weight and floating in our
+atmosphere, what must occur when they come near each other? Manifestly
+the repellent poles will retreat from each other, while the attractive
+poles will approach and finally lock themselves together. And
+supposing the particles, instead of a single pair, to possess several
+pairs of poles arranged at definite points over their surfaces; you
+can then picture them, in obedience to their mutual attractions and
+repulsions, building themselves together to form masses of definite
+shape and structure.
+
+Imagine the molecules of water in calm cold air to be gifted with
+poles of this description, which compel the particles to lay
+themselves together in a definite order, and you have before your
+mind's eye the unseen architecture which finally produces the visible
+and beautiful crystals of the snow. Thus our first notions and
+conceptions of poles are obtained from the sight of our eyes in
+looking at the effects of magnetism; and we then transfer these
+notions and conceptions to particles which no eye has ever seen. The
+power by which we thus picture to ourselves effects beyond the range
+of the senses is what philosophers call the Imagination, and in the
+effort of the mind to seize upon the unseen architecture of crystals,
+we have an example of the "scientific use" of this faculty. Without
+imagination we might have _critical_ power, but not _creative_ power
+in science.
+
+
+Architecture of Lake Ice.
+
+We have thus made ourselves acquainted with the beautiful snow-flowers
+self-constructed by the molecules of water in calm, cold air. Do the
+molecules show this architectural power when ordinary water is frozen?
+What, for example, is the structure of the ice over which we skate in
+winter? Quite as wonderful as the flowers of the snow. The observation
+is rare, if not new, but I have seen in water slowly freezing
+six-rayed ice-stars formed, and floating free on the surface. A
+six-rayed star, moreover, is typical of the construction of all our
+lake ice. It is built up of such forms wonderfully interlaced.
+
+Take a slab of lake ice and place it in the path of a concentrated
+sunbeam. Watch the track of the beam through the ice. Part of the beam
+is stopped, part of it goes through; the former produces internal
+liquefaction, the latter has no effect whatever upon the ice. But the
+liquefaction is not uniformly diffused. From separate spots of the ice
+little shining points are seen to sparkle forth. Every one of those
+points is surrounded by a beautiful liquid flower with six petals.
+
+Ice and water are so optically alike that unless the light fall
+properly upon these flowers you cannot see them. But what is the
+central spot? A vacuum. Ice swims on water because, bulk for bulk, it
+is lighter than water; so that when ice is melted it shrinks in size.
+Can the liquid flowers then occupy the whole space of the ice melted?
+Plainly no. A little empty space is formed with the flowers, and this
+space, or rather its surface, shines in the sun with the lustre of
+burnished silver.
+
+In all cases the flowers are formed parallel to the surface of
+freezing. They are formed when the sun shines upon the ice of every
+lake; sometimes in myriads, and so small as to require a magnifying
+glass to see them. They are always attainable, but their beauty is
+often marred by internal defects of the ice. Every one portion of the
+same piece of ice may show them exquisitely, while a second portion
+shows them imperfectly.
+
+Annexed is a very imperfect sketch of these beautiful figures.
+
+Here we have a reversal of the process of crystallization. The
+searching solar beam is delicate enough to take the molecules down
+without deranging the order of their architecture. Try the experiment
+for yourself with a pocket-lens on a sunny day. You will not find the
+flowers confused; they all lie parallel to the surface of freezing. In
+this exquisite way every bit of the ice over which our skaters glide
+in winter is put together.
+
+I said that a portion of the sunbeam was stopped by the ice and
+liquefied it. What is this portion? The dark heat of the sun. The
+great body of the light waves and even a portion of the dark ones,
+pass through the ice without losing any of their heating power. When
+properly concentrated on combustible bodies, even after having passed
+through the ice, their burning power becomes manifest.
+
+[Illustration: LIQUID FLOWERS IN LAKE ICE.]
+
+And the ice itself may be employed to concentrate them. With an
+ice-lens in the polar regions Dr. Scoresby has often concentrated the
+sun's rays so as to make them burn wood, fire gunpowder, and melt
+lead; thus proving that the heating power is retained by the rays,
+even after they have passed through so cold a substance.
+
+By rendering the rays of the electric lamp parallel, and then sending
+them through a lens of ice, we obtain all the effects which Dr.
+Scoresby obtained with the rays of the sun.
+
+[Illustration]
+
+
+
+
+THE ORGANIC WORLD
+
+(FROM THE ELEMENTS OF SCIENCE.)
+
+BY ST. GEORGE MIVART F.R.S.
+
+
+The number of all the various kinds of living creatures is so enormous
+that it would be impossible to study them profitably, were they not
+classified in an orderly manner. Therefore the whole mass has been
+divided, in the first place, into two supreme groups, fancifully
+termed kingdoms--the "animal kingdom" and the "vegetal kingdom." Each
+of these is subdivided into an orderly series of subordinate groups,
+successively contained one a within the other, and named sub-kingdoms,
+classes, orders, families, genera and species. The lowest group but
+one is the "genus," which contains one or more different kinds termed
+"species," as e.g., the species "wood anemone" and the species "blue
+titmouse." The lowest group of all--a species--may be said to consist
+of individuals which differ from each other only by trifling
+characters, such as characters due to difference of sex, while their
+peculiar organization is faithfully reproduced by generation as a
+whole, though small individual differences exist in all cases.
+
+The vegetal, or vegetable, kingdom, consists of the great mass of
+flowering plants, many of which, however, have such inconspicuous
+flowers that they are mistakenly regarded as flowerless, as is often
+the case with the grasses, the pines, and the yews. Another mass, or
+sub-kingdom, of plants consists of the really flowerless plants, such
+as the ferns, horsetails (Fig. 1), lycopods, and mosses. Sea and
+fresh-water weeds (_algæ_), and mushrooms, or "moulds," of all kinds
+(_fungi_), amongst which are the now famous "bacteria," constitute a
+third and lowest set of plants.
+
+[Illustration: FIG. 1. HORSE-TAIL (_Equisetum drummondii_).]
+
+The animal kingdom consists, first, of a sub-kingdom of animals which
+possess a spinal column, or backbone, and which are known as
+vertebrate animals. Such are all beasts, birds, reptiles, and fishes.
+There are also a variety of remotely allied marine organisms known as
+tunicates, sea-squirts, or ascidians (Fig. 2). There is, further, an
+immense group of arthropods, consisting of all insects, crab-like
+creatures, hundred-legs and their allies, with spiders, scorpions,
+tics and mites. We have also the sub-kingdom of shell-fish or
+molluscs, including cuttle-fishes, snails, whelks, limpets, the
+oyster, and a multitude of allied forms. A multitudinous sub-kingdom of
+worms also exists, as well as another of star-fishes and their
+congeners. There is yet another of zoophytes, or polyps, and another
+of sponges, and, finally, we have a sub-kingdom of minute creatures,
+or animalculæ, of very varied forms, which may make up the sub-kingdom
+of _Protozoa_, consisting of animals which are mostly unicellular.
+
+[Illustration: FIG. 2. A TUNICATE (_Ascidia_).]
+
+Multitudinous and varied as are the creatures which compose this
+immense organic world, they nevertheless exhibit a very remarkable
+uniformity of composition in their essential structure. Every living
+creature from a man to a mushroom, or even to the smallest animalcule
+or unicellular plant is always partly fluid, but never entirely so.
+Every living creature also consists in part (and that part is the most
+active living part) of a soft, viscid, transparent, colorless
+substance, termed protoplasm, which can be resolved into the four
+elements, oxygen, hydrogen, nitrogen and carbon. Besides these four
+elements, living organisms commonly contain sulphur, phosphorus,
+chlorine, potassium, sodium, calcium, magnesium and iron.
+
+In the fact that living creatures always consist of the four elements,
+oxygen, hydrogen, nitrogen and carbon, we have a fundamental character
+whereby the organic and inorganic (or non-living) worlds are to be
+distinguished, for as we have seen, inorganic bodies, instead of being
+thus uniformly constituted, may consist of the most diverse elements
+and sometimes of but two or even of only one.
+
+Again, many minerals, such as crystals, are bounded by plain surfaces,
+and, with very few exceptions (spathic and hematite iron and dolomite
+are such exceptions) none are bounded by curved lines and surfaces,
+while living organisms are bounded by such lines and surfaces.
+
+Yet, again, if a crystal be cut through, its internal structure will
+be seen to be similar throughout. But if the body of any living
+creature be divided, it will, at the very least, be seen to consist of
+a variety of minute distinct particles, called "granules," variously
+distributed throughout its interior.
+
+All organisms consist either--as do the simplest, mostly microscopic,
+plants and animals--of a single minute mass of protoplasm, or of a
+few, or of many, or of an enormous aggregation of such before-mentioned
+particles, each of which is one of those bodies named a "cell" (Fig.
+3). Cells may, or may not, be enclosed in an investing coat or
+"cell-wall." Every cell generally contains within it a denser,
+normally spheroidal, body known as the nucleus.
+
+Now protoplasm is a very unstable substance--as we have seen many
+substances are whereof nitrogen is a component part--and it possesses
+active properties which are not present in the non-living, or
+inorganic world. In the latter, differences of temperature will
+produce motion in the shape of "currents," as we have seen with
+respect to masses of air and water. But in a portion of protoplasm,
+an internal circulation of currents in definite lines will establish
+itself from other causes.
+
+Inorganic bodies, as we have seen, will expand with heat, as they may
+also do from imbibing moisture; but living protoplasm has an
+apparently spontaneous power of contraction and expansion under
+certain external conditions which do not occasion such movements in
+inorganic matter.
+
+[Illustration: FIG. 3. CELL FROM A SALAMANDER. _n_, nucleus; _n'_,
+nucleolus embedded in the network of chromatin threads; _k_, network
+of the cell external to the nucleus; _a_, attraction-sphere or
+archoplasm containing minute bodies called centrosomes; _cl_, membrane
+enclosing the cell externally, _nl_, membrane surrounding the nucleus;
+_c_, centrosomes.]
+
+Under favoring conditions, protoplasm has a power of performing
+chemical changes, which result in producing heat far more gently and
+continuously than it is produced by the combustion of inorganic
+bodies. Thus it is that the heat is produced which makes its presence
+evident to us in what we call "warm-blooded animals," the most
+warm-blooded of all being birds.
+
+Protoplasm has also the wonderful power of transforming certain
+adjacent substances into material like itself--into its own
+substance--and so, in a sense, creating a new material. Thus it is
+that organisms have the power to nourish themselves and grow. An
+animal would vainly swallow the most nourishing food if the ultimate,
+protoplasmic particles of its body had not this power of
+"transforming" suitable substances brought near them in ways to be
+hereinafter noticed.
+
+Without that, no organism could ever "grow." The growth of organisms
+is utterly different from the increase in size of inorganic bodies.
+Crystals, as we have seen, grow merely by external increment; but
+organisms grow by an increment which takes place in the very innermost
+substance of the tissues which compose their bodies, and the innermost
+substance of the cells which compose such tissues; this peculiar form
+of growth is termed _intussusception_.
+
+Protoplasm, after thus augmenting its mass, has a further power of
+spontaneous division, whereby the mass of the entire organism whereof
+such protoplasm forms a part, is augmented and so growth is brought
+about.
+
+The small particles of protoplasm which constitute "cells" are far
+indeed from being structureless. Besides the nucleus already mentioned
+there is a delicate network of threads of a substance called
+_chromatin_ within it, and another network permeating the fluid of the
+cell substance, which invest the nucleus often with further
+complications. These networks generally perform (or undergo) a most
+complex series of changes every time a cell spontaneously divides. In
+certain cases, however, it appears that the nucleus divides into two
+in a more simple fashion, the rest of the cell contents subsequently
+dividing--each half enclosing one part of the previously divided
+nucleus. It is by a continued process of cell division that the
+complex structures of the most complex organisms is brought about.
+
+The division of a cell, or particle of protoplasm, is indeed a
+necessary consequence of its complete nutrition.
+
+For new material can only be absorbed by its surface. But as the cell
+grows, the proportion borne by its surface to its mass, continually
+decreases; therefore this surface must soon be too small to take in
+nourishment enough, and the particle, or cell, must therefore either
+die or divide. By dividing, its parts can continue the nutritive
+process till their surface, in turn, becomes insufficient, when they
+must divide again, and so on. Thus the term "feeding" has two senses.
+"To feed a horse," ordinarily means to give it a certain quantity of
+hay, oats or what not; and such indeed is one kind of feeding. But
+obviously, if the nourishment so taken could not get from the stomach
+and intestines into the ultimate particles and cells of the horse's
+body, the horse could not be nourished, and still less could it grow.
+It is this latter process, called assimilation, which is the real and
+essential process of feeding, to which the process ordinarily so
+called is but introductory.
+
+Protoplasm has also the power of forming and ejecting from its own
+substance, other substances which it has made, but which are of a
+different nature to its own. This function, as before said, is termed
+secretion; and we know the liver secretes bile, and that the cow's
+udder secretes milk.
+
+Here again we have an external and an internal process. The milk is
+drawn forth from a receptacle, the udder, into which it finds its way,
+and so, in a superficial sense, it may be called an organ of
+secretion. Nevertheless the true internal secretion takes place in
+the innermost substance of the cells or particles of protoplasm, of
+the milk-land, which particles really form that liquid.
+
+But every living creature consists at first entirely of a particle of
+protoplasm. Therefore every other kind of substance which may be found
+in every kind of plant or animal, must have been formed through it,
+and be, in fact, a secretion from protoplasm. Such is the rosy cheek
+of an apple, or of a maiden, the luscious juice of the peach, the
+produce of the castor-oil plant, the baleen that lines the whale's
+enormous jaws, as well as that softest product, the fur of the
+chinchilla. Indeed, every particle of protoplasm requires, in order
+that it may live, a continuous process of exchange. It needs to be
+continuously first built up by food, and then broken down by
+discharging what is no longer needful for its healthy existence. Thus
+the life of every organism is a life of almost incessant change, not
+only in its being as a whole, but in that of all its protoplasmic
+particles also.
+
+[Illustration: FIG. 4. AMOEBA SHOWN IN TWO OF THE MANY IRREGULAR
+SHAPES IT ASSUMES. _(After Howes_.)
+
+The clear space within it is a contractile vesicle. The dark body is
+the nucleus. In the right-hand figure there is shown a particle of
+food, passing through the external surface.]
+
+
+Prominent among such processes is that of an interchange of gases
+between the living being and its environment. This process consists in
+an absorption of oxygen and a giving-out of carbonic acid, which
+exchange is termed respiration.
+
+Lastly, protoplasm has a power of motion when appropriately acted on.
+It will then contract or expand its shape by alternate protrusions and
+retractions of parts of its substance. These movements are termed
+amoebiform, because they quite resemble the movements of a small
+animalcule which is named amoeba. (See Fig. 4.)
+
+Such is the ultimate structure, and such are the fundamental
+activities or functions of living organisms, as far as they can here
+be described, from the lowest animalcule and unicellular plant, up to
+the most complex organisms and the body of man himself.
+
+[Illustration]
+
+
+
+
+INHABITANTS OF MY POOL
+
+(FROM MAGIC GLASSES.)
+
+BY ARABELLA B. BUCKLEY.
+
+
+The pool lies in a deep hollow among a group of rocks and boulders,
+close to the entrance of the cove, which can only be entered at low
+water; it does not measure more than two feet across, so that you can
+step over it, if you take care not to slip on the masses of green and
+brown seaweed growing over the rocks on its sides, as I have done many
+a time when collecting specimens for our salt-water aquarium. I find
+now the only way is to lie flat down on the rock, so that my hands and
+eyes are free to observe and handle, and then, bringing my eye down to
+the edge of the pool, to lift the seaweeds and let the sunlight enter
+into the chinks and crannies. In this way I can catch sight of many a
+small being either on the seaweed or the rocky ledges, and even
+creatures transparent as glass become visible by the thin outline
+gleaming in the sunlight. Then I pluck a piece of seaweed, or chip off
+a fragment of rock with a sharp-edged collecting knife, bringing away
+the specimen uninjured upon it, and place it carefully in its own
+separate bottle to be carried home alive and well.
+
+Now though this little pool and I are old friends, I find new
+treasures in it almost every time I go, for it is almost as full of
+living things as the heavens are of stars, and the tide as it comes
+and goes brings many a mother there to find a safe home for her little
+ones, and many a waif and stray to seek shelter from the troublous
+life of the open ocean.
+
+You will perhaps find it difficult to believe that in this rock-bound
+basin there can be millions of living creatures hidden away among the
+fine feathery weeds; yet so it is. Not that they are always the same.
+At one time it may be the home of myriads of infant crabs, not an
+eighth of an inch long, another of baby sea-urchins only visible to
+the naked eye as minute spots in the water, at another of young
+jelly-fish growing on their tiny stalks, and splitting off one by one
+as transparent bells to float away with the rising tide. Or it may be
+that the whelk has chosen this quiet nook to deposit her leathery
+eggs; or young barnacles, periwinkles, and limpets are growing up
+among the green and brown tangles, while the far-sailing velella and
+the stay-at-home sea-squirts, together with a variety of other
+sea-animals, find a nursery and shelter in their youth in this quiet
+harbor of rest.
+
+And besides these casual visitors there are numberless creatures which
+have lived and multiplied there, ever since I first visited the pool.
+Tender red, olive-colored, and green seaweeds, stony corallines, and
+acorn-barnacles lining the floor, sea-anemones clinging to the sides,
+sponges tiny and many-colored hiding under the ledges, and limpets and
+mussels wedged in the cracks. These can be easily seen with the naked
+eye, but they are not the most numerous inhabitants; for these we
+must search with a magnifying glass, which will reveal to us wonderful
+fairy-forms, delicate crystal vases with tiny creatures in them whose
+transparent lashes make whirlpools in the water, living crystal bells
+so tiny that whole branches of them look only like a fringe of hair,
+jelly globes rising and falling in the water, patches of living jelly
+clinging to the rocky sides of the pool, and a hundred other forms,
+some so minute that you must examine the fine sand in which they lie
+under a powerful microscope before you can even guess that they are
+there.
+
+[Illustration: FIG. 1. GROUP OF SEAWEEDS.
+
+(Natural size.)
+
+1, _Ulva Linza._ 2, _Sphacelaria filicina._ 3, _Polysiphonia
+urceolata._ 4, _Corallina officinalis._]
+
+So it has proved a rich hunting-ground, where summer and winter,
+spring and autumn, I find some form to put under my magic glass. There
+I can watch it for weeks growing and multiplying under my care; moved
+only from the aquarium, where I keep it supplied with healthy
+sea-water, to the tiny transparent trough in which I place it for a
+few hours to see the changes it has undergone. I could tell you
+endless tales of transformations in these tiny lives, but I want
+to-day to show you a few of my friends, most of which I brought
+yesterday fresh from the pool, and have prepared for you to examine.
+
+[Illustration: FIG. 2. _Ulva lactuca_, A GREEN-SEAWEED, GREATLY
+MAGNIFIED TO SHOW STRUCTURE. (_After Orested)._
+
+s, Spores in the cells, _ss_, Spores swimming out. _h_, Holes through
+which spores have escaped.]
+
+Let us begin with seaweeds. I have said that there are three leading
+colors in my pool--green, olive, and red--and these tints mark roughly
+three kinds of weed, though they occur in an endless variety of
+shapes. Here is a piece of the beautiful pale green seaweed, called
+the Laver or Sea-Lettuce, _Ulva Linza_ (1, Fig. 1),[1] which grows in
+long ribbons in a sunny nook in the water. I have placed under the
+first microscope a piece of this weed which is just sending out young
+seaweeds in the shape of tiny cells, with lashes very like those we
+saw coming from the moss-flower, and I have pressed them in the
+position in which they would naturally leave the plant. You will also
+see on this side several cells in which these tiny spores are forming,
+ready to burst out and swim; for this green weed is merely a
+collection of cells, like the single-celled plants on land. Each cell
+can work as a separate plant; it feeds, grows, and can send out its
+own young spores.
+
+[Footnote 1: The slice given in Fig. 2 is from a broader-leaved form,
+_U. lactuca_, because this species, being composed of only one layer
+of cells, is better seen. _Ulva Linza_ is composed of two layers of
+cells.]
+
+This deep olive-green feathery weed (2, Fig. 1), of which a piece is
+magnified under the next microscope (2, Fig. 3), is very different. It
+is a higher plant, and works harder for its living, using the darker
+rays of sunlight which penetrate into shady parts of the pool. So it
+comes to pass that its cells divide the work. Those of the feathery
+threads make the food, while others, growing on short stalks on the
+shafts of the feather, make and send out the young spores.
+
+Lastly, the lovely red threadlike weeds, such as this _Polysiphonia
+urceolata_ (3, Fig. 1), carry actual urns on their stems like those of
+mosses. In fact, the history of these urns (see 3, Fig. 3), is much
+the same in the two classes of plants, only that instead of the urn
+being pushed up on a thin stalk as in the moss, it remains on the
+seaweed close down to the stem, when it grows out of the plant-egg,
+and the tiny plant is shut in till the spores are ready to swim out.
+
+[Illustration: FIG. 3. THREE SEAWEEDS OF FIG. 1 MUCH MAGNIFIED TO SHOW
+FRUITS. (_Harvey._)
+
+2, _Sphacelaria filicina._ 3, _Polysiphonia urceolata._ 4, _Corallina
+officinalis._]
+
+The stony corallines (4, Figs. 1 and 3), which build so much carbonate
+of lime into their stems, are near relations of the red seaweeds.
+There are plenty of them in my pool. Some of them, of a deep purple
+color, grow upright in stiff groups about three or four inches high;
+and others, which form crusts over the stones and weeds, are a pale
+rose color; but both kinds, when the plant dies, leaving the stony
+skeleton (1, Fig. 4), are a pure white, and used to be mistaken for
+corals. They belong to the same order of plants as the red weeds,
+which all live in shady nooks in the pools, and are the highest of
+their race.
+
+[Illustration: FIG. 4. CORALLINE AND SERTULARIA, TO SHOW LIKENESS
+BETWEEN THE ANIMAL SERTULARIA AND THE PLANT CORALLINE.
+
+1, _Corallina officinalis._ 2, _Sertularia filicula._]
+
+My pool is full of different forms of these four weeds. The green
+ribbons float on the surface rooted to the sides of the pool, and, as
+the sun shines upon it, the glittering bubbles rising from them show
+that they are working up food out of the air in the water, and giving
+off oxygen. The brown weeds lie chiefly under the shelves of rocks,
+for they can manage with less sunlight, and use the darker rays which
+pass by the green weeds; and last of all, the red weeds and
+corallines, small and delicate in form, line the bottom of the pool in
+its darkest nooks.
+
+And now if I hand round two specimens,--one a coralline, and the other
+something you do not yet know,--I am sure you will say at first sight
+that they belong to the same family, and, in fact, if you buy at the
+seaside a group of seaweeds gummed on paper, you will most likely get
+both these among them. Yet the truth is; that while the coralline (1,
+Fig. 4) is a plant, the other specimen (2), which is called
+_Sertularia filicula_, is an animal.
+
+This special sertularian grows up right in my pool on stones or often
+on seaweeds, but I have here (Fig. 5) another and much smaller one
+which lives literally in millions hanging its cups downwards. I find
+it not only under the narrow ledges of the pool sheltered by the
+seaweed, but forming a fringe along all the rocks on each side of the
+cove near to low-water mark, and for a long time I passed it by
+thinking it was of no interest. But I have long since given up
+thinking this of anything, especially in my pool, for my magic glass
+has taught me that there is not even a living speck which does not
+open out into something marvellous and beautiful. So I chipped off a
+small piece of rock and brought the fringe home, and found, when I
+hung it up in clear sea-water as I have done over this glass trough
+(Fig. 5) and looked at it through the lens, that each thread of the
+dense fringe, in itself not a quarter of an inch deep, turns out to be
+a tiny sertularian with at least twenty mouths. You can see this with
+your pocket lens even as it hangs here, and when you have examined it
+you can by and by take off one thread and put it carefully in the
+trough. I promise you a sight of the most beautiful little beings
+which exist in nature.
+
+[Illustration: FIG. 5. _Sertularia tenella_, HANGING FROM A SPLINT OF
+ROCK OVER A WATER TROUGH. ALSO PIECE ENLARGED TO SHOW THE ANIMAL
+PROTRUDING.]
+
+Come and look at it. It is a horny-branched stem with a double row of
+tiny cups all along each side. Out of these cups there appear a row of
+tiny cups all along each side (see Fig. 5), Out of these cups there
+appear from time to time sixteen minute transparent tentacles as fine
+as spun glass, which wave about in the water. If you shake the glass a
+little, in an instant each crystal star vanishes into its cup, to come
+out again a few minutes later; so that now here, now there, the
+delicate animal-flowers spread out on each side of the stem, and the
+tree is covered with moving beings. These tentacles are feelers, which
+lash food into a mouth and stomach in each cup, where it is digested
+and passed, through a hole in the bottom, along a jelly thread which
+runs down the stem and joins all the mouths together. In this way the
+food is distributed all over the tree, which is, in fact, one animal
+with many feeding-cups. Some day I will show you one of these cups
+with the tentacles stretched out and mounted on a slide, so that you
+can examine a tentacle with a very strong magnifying power. You will
+then see that it is dotted over with cells, in which are coiled fine
+threads. The animal uses these threads to paralyze the creatures on
+which it feeds, for at the base of each thread there is a poison
+gland.
+
+In the larger Sertularia the whole branched tree is connected by jelly
+threads, running through the stem, and all the thousands of mouths are
+spread out in the water. One large form called _Sertularia cupressina_
+grows sometimes three feet high and bears as many as a hundred
+thousand cups, with living mouths, on its branches.
+
+The next of my minute friends I can only show to the class in a
+diagram, but you will see it under the fourth microscope by and by. I
+had great trouble in finding it yesterday, though I know its haunts
+upon the green weed, for it is so minute and transparent that even
+when the weed is in a trough a magnifying-glass will scarcely detect
+it. And I must warn you that if you want to know any of the minute
+creatures we are studying, you must visit one place constantly. You
+may in a casual way find many of them on seaweed, or in the damp ooze
+and mud, but it will be by chance only; to look for them with any
+certainty you must take trouble in making their acquaintance.
+
+[Illustration: FIG. 6. _Thuricolla folliculata_ and _Chilomonas
+amygdalum_. (_Saville Kent_.)
+
+1, _Thuricolla_ erect. 2, Retracted. 3, Dividing. 4, _Chilomonas
+amygdalum. hc,_ Horny carapace, _cv_, Contractile vesicle. _v_ Closing
+valves.]
+
+Turning then to the diagram (Fig. 6) I will describe it as I hope you
+will see it under the microscope--a curious, tiny, perfectly
+transparent open-mouthed vase standing upright on the weed, and having
+an equally transparent being rising up in it and waving its tiny
+lashes in the water. This is really all one animal, the vase _hc_
+being the horny covering or carapace of the body, which last stands up
+like a tube in the centre. If you watch carefully, you may even see
+the minute atoms of food twisting round inside the tube until they are
+digested, after they have been swept in at the wide open mouth by the
+whirling lashes. You will see this more clearly if you put a little
+rice-flour, very minutely powdered and colored by carmine, into the
+water; for you can trace these red atoms into some round spaces called
+_vacuoles_ which are dotted over the body of the animal, and are
+really globules of watery fluid in which the food is probably partly
+digested.
+
+You will notice, however, one round clear space _(cv)_ into which they
+do not go, and after a time you will be able to observe that this
+round spot closes up or contracts very quickly, and then expands again
+very slowly. As it expands it fills with a clear fluid, and
+naturalists have not yet decided exactly what work it does. It may
+serve the animal either for breathing, or as a very simple heart,
+making the fluids circulate in the tube. The next interesting point
+about this little being is the way it retreats into its sheltering
+vase. Even while you are watching, it is quite likely it may all at
+once draw itself down to the bottom as in No. 2, and folding down the
+valves _w_ of horny teeth which grow on each side, shut itself in from
+some fancied danger. Another very curious point is that, besides
+sending forth young ones, these creatures multiply by dividing in two
+(see No. 3, Fig. 6), each one closing its own part of the vase into a
+new home.
+
+There are hundreds of these Infusoria, as they are called, in my pond,
+some with vases, some without, some fixed to weeds and stones, others
+swimming about freely. Even in the water-trough in which this
+Thuricolla stands, I saw several smaller forms, and the next
+microscope has a trough filled with the minutest form of all, called a
+Monad. These are so small that two thousand of them could lie side by
+side in an inch; that is, if you could make them lie at all, for they
+are the most restless little beings, darting hither and thither,
+scarcely even halting except to turn back. And yet though there are so
+many of them, and as far as we know they have no organs of sight, they
+never run up against each other, but glide past more cleverly than any
+clear-sighted fish. These creatures are mostly to be found among
+decaying seaweed, and though they are so tiny, you can still see
+distinctly the clear space contracting and expanding within them.
+
+[Illustration: FIG. 7. LIVING DIATOMS.
+
+_a, Cocconema lanceolatum. b, Bacillaria paradoxa. c, Gomphonema
+marinum. d, Diatoma hyalina_.]
+
+But if there are so many thousands of mouths to feed, on the tree-like
+Sertulariæ as well as in all these Infusoria, where does the food come
+from? Partly from the numerous atoms of decaying life all around, and
+the minute eggs of animals and spores of plants; but besides these,
+the pool is full of minute living plants--small jelly masses with
+solid coats of flint which are moulded into most lovely shapes. Plants
+formed of jelly and flint! You will think I am joking, but I am not.
+These plants, called Diatoms, which live both in salt and fresh water,
+are single cells feeding and growing just like those we took from the
+water-butt, only that instead of a soft covering they build up a
+flinty skeleton. They are so small, that many of them must be
+magnified to fifty times their real size before you can even see them
+distinctly. Yet the skeletons of these almost invisible plants are
+carved and chiselled in the most delicate patterns. I showed you a
+group of these in our lecture on magic glasses, and now I have brought
+a few living ones that we may learn to know them. The diagram (Fig. 7)
+shows the chief forms you will see on the different slides.
+
+The first one, _Sacillaria paradoxa_ (_b_, Fig. 7), looks like a
+number of rods clinging one to another in a string, but each one of
+these is a single-celled plant with a jelly cell surrounding the
+flinty skeleton. You will see that they move to and fro over each
+other in the water.
+
+The next two forms, _a_ and _c_, look much more like plants, for the
+cells arrange themselves on a jelly stem, which by and by disappears,
+leaving only the separate flint skeletons. The last form, _d_, is
+something midway between the other forms, the separate cells hang on
+to each other and also on to a straight jelly stem.
+
+[Illustration: FIG. 8. A DIATOM (_Diatoma vulgare_) GROWING.
+
+_a, b,_ Flint skeleton inside the jelly-cell. _a, c_ and _d, b_, Two
+flint skeletons formed by new valves, _c_ and _d_, forming within the
+first skeleton.]
+
+Another species of Diatoma (Fig. 8) called _Diatoma vulgare_, is a
+very simple and common form, and will help to explain how these plants
+grow. The two flinty valves _a, b_ inside the cell are not quite the
+same size; the older one _a_ is larger than the younger one _b_ and
+fits over it like the cover of a pill-box. As the plant grows, the
+cell enlarges and forms two more valves, one _c_ fitting into the
+cover _a_, so as to make a complete box _ac_, and a second, _d_, back
+to back with _c_, fitting into the valve _b_, and making another
+complete _bd_. This goes on very rapidly, and in this plant each new
+cell separates as it is formed, and the free diatoms move about quite
+actively in the water.
+
+If you consider for a moment, you will see that, as the new valves
+always fit into the old ones, each must be smaller than the last, and
+so there comes a time when the valves have become too small to go on
+increasing. Then the plant must begin afresh. So the two halves of the
+last cell open, and throwing out their flinty skeletons, cover
+themselves with a thin jelly layer, and form a new cell which grows
+larger than any of the old ones. These, which are spore-cells, then
+form flinty valves inside, and the whole thing begins again.
+
+Now, though the plants themselves die, or become the food of minute
+animals, the flinty skeletons are not destroyed, but go on
+accumulating in the waters of the ponds, lakes, rivers, and seas, all
+over the world. Untold millions have no doubt crumbled to dust and
+gone back into the waters, but untold millions also have survived. The
+towns of Berlin in Europe and of Richmond in the United States are
+actually built upon ground called "infusorial earth," composed almost
+entirely of valves of these minute diatoms which have accumulated to a
+thickness of more than eighty feet! Those under Berlin are fresh-water
+forms, and must have lived in a lake, while those of Richmond belong
+to salt-water forms. Every inch of the ground under those cities
+represents thousands and thousands of living plants which flourished
+in ages long gone by, and were no larger than those you will see
+presently under the microscope.
+
+These are a very few of the microscopic inhabitants of my pond, but,
+as you will confuse them if I show you too many, we will conclude with
+two rather larger specimens, and examine them carefully. The first,
+called the Cydippe, is a lovely, transparent living ball, which I want
+to explain to you because it is so wondrously beautiful. The second,
+the Sea-mat or Flustra, looks like a crumpled drab-colored seaweed,
+but is really composed of many thousands of grottos, the homes of tiny
+sea-animals.
+
+[Illustration: FIG. 9. _Cydippe Pileus_.
+
+1, Animal with tentacles _t_, bearing small tendrils _t'_. 2, Body of
+animal enlarged. _m_, Mouth. _c_, Digestive cavity. _s_, Sac into
+which the tentacles are withdrawn. _p_, Bands with comb-like plates.
+3, Portion of a band enlarged to show the moving plates _p_.]
+
+Let us take the Cydippe first (1, Fig. 9). I have six here, each in a
+separate tumbler, and could have brought many more, for when I dipped
+my net in the pool yesterday such numbers were caught in it that I
+believe the retreating tide must just have left a shoal behind. Put a
+tumbler on the desk in front of you, and if the light falls well upon
+it you will see a transparent ball about the size of a large pea
+marked with eight bright bands, which begin at the lower end of the
+ball and reach nearly to the top, dividing the outside into sections
+like the ribs of a melon. The creature is so perfectly transparent
+that you can count all the eight bands.
+
+At the top of the ball is a slight bulge which is the mouth (_m_ 2,
+Fig. 9), and from it, inside the ball hangs a long bag or stomach,
+which opens below into a cavity, from which two canals branch out, one
+on each side, and these divide again into four canals which go one
+into each of the tubes running down the bands. From this cavity the
+food, which is digested in the stomach, is carried by the canals all
+over the body. The smaller tubes which branch out of these canals
+cannot be seen clearly without a very strong lens, and the only other
+parts you can discern in this transparent ball are two long sacs on
+each side of the lower end. These are the tentacle sacs, in which are
+coiled up the tentacles, which we shall describe presently. Lastly you
+can notice that the bands outside the globe are broader in the middle
+than at the ends, and are striped across by a number of ridges.
+
+In moving the tumblers the water has naturally been shaken, and the
+creature being alarmed will probably at first remain motionless. But
+very soon it will begin to play in the water, rising and falling, and
+swimming gracefully from side to side. Now you will notice a curious
+effect, for the bands will glitter and become tinged with prismatic
+colors, till, as it moves more and more rapidly these colors,
+reflected in the jelly, seem to tinge the whole ball with colors like
+those on a soap-bubble, while from the two sacs below come forth two
+long transparent threads like spun glass. At first these appear to be
+simple threads, but as they gradually open out to about four or five
+inches, smaller threads uncoil on each side of the line till there are
+about fifty on each line. These short tendrils are never still for
+long; as the main threads wave to and fro, some of the shorter ones
+coil up and hang like tiny beads, then these uncoil and others roll
+up, so that these graceful floating lines are never two seconds alike.
+
+We do not really know their use. Sometimes the creature anchors itself
+by them, rising and falling as they stretch out or coil up; but more
+often they float idly behind it in the water. At first you would
+perhaps think that they served to drive the ball through the water,
+but this is done by a special apparatus. The cross ridges which we
+noticed on the bands are really flat comb-like plates (_p_, Fig. 9),
+of which there are about twenty or thirty on each band; and these
+vibrate very rapidly, so that two hundred or more paddles drive the
+tiny ball through the water. This is the cause of the prismatic
+colors; for iridescent tints are produced by the play of light upon
+the glittering plates, as they incessantly change their angle.
+Sometimes they move all at once, sometimes only a few at a time, and
+it is evident the creature controls them at will.
+
+This lovely fairy-like globe, with its long floating tentacles and
+rainbow tints, was for a long time classed with the jelly-fish; but it
+really is most nearly related to the sea-anemones, as it has a true
+central cavity which acts as a stomach, and many other points in
+common with the _Actinozoa_. We cannot help wondering, as the little
+being glides hither and thither, whether it can see where it is going.
+It has nerves of a low kind which start from a little dark spot (_ng_)
+exactly at the south pole of the ball, and at that point a sense-organ
+of some kind exists, but what impression the creature gains from it of
+the world outside we cannot tell.
+
+I am afraid you may think it dull to turn from such a beautiful being
+as this, to the gray leaf which looks only like a dead dry seaweed;
+yet you will be wrong, for a more wonderful history attaches to this
+crumpled dead-looking leaf than to the lovely jelly-globe.
+
+[Illustration: FIG. 10. THE SEA-MAT OR FLUSTRA (_Flustra foliacea_).
+
+1, Natural size. 2, Much magnified, _s_, Slit caused by drawing in of
+the animal _a_.]
+
+First of all I will pass round pieces of the dry leaf (1, Fig. 10),
+and while you are getting them I will tell you where I found the
+living ones. Great masses of the Flustra, as it is called, line the
+bottom and sides of my pool. They grow in tufts, standing upright on
+the rock, and looking exactly like hard gray seaweeds, while there is
+nothing to lead you to suspect that they are anything else. Yesterday
+I chipped off very carefully a piece of rock with a tuft upon it, and
+have kept it since in a glass globe by itself with sea-water, for the
+little creatures living in this marine city require a very good supply
+of healthy water and air. I have called it a "marine city," and now I
+will tell you why. Take the piece in your hand and run your finger
+gently up and down it; you will glide quite comfortably from the lower
+to the higher part of the leaf, but when you come back you will feel
+your finger catch slightly on a rough surface. Your pocket lens will
+show you why this is, for if you look through it at the surface of the
+leaf you will see it is not smooth, but composed of hundreds of tiny
+alcoves with arched tops; and on each side of these tops stand two
+short blunt spines, making four in all, pointing upwards, so as partly
+to cover the alcove above. As your finger went up it glided over the
+spines, but on coming back it met their points. This is all you can
+see in the dead specimen; I must show you the rest by diagrams, and by
+and by under the microscope.
+
+First, then, in the living specimen which I have here, those alcoves
+are not open as in the dead piece, but covered over with a transparent
+skin, in which, near the top of the alcove just where the curve
+begins, is a slit (_s_ 2, Fig. 10) Unfortunately, the membrane
+covering this alcove is too dense for you to distinguish the parts
+within. Presently, however, if you are watching a piece of this living
+leaf in a flat water-cell under the microscope, you will see the slit
+slowly open, and begin to turn as it were inside out, exactly like the
+finger of a glove, which has been pushed in at the tip, gradually
+rises up when you put your finger inside it. As this goes on, a bundle
+of threads appears, at first closed like a bud, but gradually opening
+out into a crown of tentacles, each one clothed with hairs. Then you
+will see that the slit was not exactly a slit after all, but the round
+edge where the sac was pushed in. Ah! you will say, you are now
+showing me a polyp like those on the sertularian tree. Not so fast, my
+friend; you have not studied what is still under the covering skin and
+hidden in the living animal. I have, however, prepared a slide with
+this membrane removed and there you can observe the different parts,
+and learn that each one of these alcoves contains a complete animal,
+and not merely one among many mouths, like the polyp on Sertularia.
+
+[Illustration: FIG. 11. DIAGRAM OF THE ANIMAL IN THE FLUSTRA OR
+SEA-MAT.
+
+1, Animal protruding. 2, Animal retracted in the sheath, _sh_,
+Covering sheath, _s_, Slit. _t_, Tentacles. _m_, Mouth. _th_, Throat,
+_st_, Stomach. _i_, Intestine, _r_, Retractor muscle, _e_, Egg-forming
+parts. _g_, Nerve-ganglion.]
+
+Each of these little beings (_a_, Fig. 10) living in its alcove has a
+mouth, throat, stomach, intestine, muscles, and nerves starting from
+the ganglion of nervous matter, besides all that is necessary for
+producing eggs and sending forth young ones. You can trace all these
+under the microscope (see 2, Fig. 11) as the creature lies curiously
+doubled up in its bed, with its body bent in a loop; the intestine
+_i_, out of which the refuse food passes, coming back close up to the
+slit. When it is at rest, the top of the sac in which it lies is
+pulled in by the retractor muscle _r_, and looks, as I have said, like
+the finger of a glove with the top pushed in. When it wishes to feed
+this top is drawn out by muscles running round the sac, and the
+tentacles open and wave in the water (1, Fig. 11).
+
+Look now at the alcoves, the homes of these animals; see how tiny they
+are and how closely they fit together. Mr. Gosse, the naturalist, has
+reckoned that there are six thousand, seven hundred and twenty alcoves
+in a square inch; then if you turn the leaf over you will see that
+there is another set, fixed back to back with these, on the other
+side, making in all, thirteen thousand, four hundred and forty
+alcoves. Now a moderate-sized leaf of flustra measures about three
+square inches, taking all the rounded lobes into account, so you will
+see we get forty thousand, three hundred and twenty as a rough
+estimate of the number of beings on this one leaf. But if you look at
+this tuft I have brought, you will find it is composed of twelve such
+leaves, and this after all is a very small part of the mass growing
+round my pool. Was I wrong, then, when I said my miniature ocean
+contains as many millions of beings as there are stars in the heavens?
+
+You will want to know how these leaves grew, and it is in this way.
+First a little free swimming animal, a mere living sac provided with
+lashes, settles down and grows into one little horny alcove, with its
+live creature inside, which in time sends off from it three to five
+buds, forming alcoves all round the top and sides of the first one,
+growing on to it. These again bud out, and you can thus easily
+understand that, in this way, in time a good-sized leaf is formed.
+Meanwhile the creatures also send forth new swimming cells, which
+settle down near to begin new leaves, and thus a tuft is formed; and
+long after the beings in earlier parts of the leaf have died and left
+their alcoves empty, those round the margin are still alive and
+spreading....
+
+If you can trace the spore-cells and urns in the seaweeds, observe the
+polyps in the Sertularia, and count the number of mouths on a branch
+of my animal fringe (Sertularia tenella); if you make acquaintance
+with the Thuricolla in its vase, and are fortunate enough to see one
+divide in two; if you learn to know some of the beautiful forms of
+diatoms, and can picture to yourself the life of the tiny inhabitants
+of the Flustra; then you will have used your microscope with some
+effect, and be prepared for an expedition to my pool, where we will go
+together some day to seek new treasures.
+
+[Illustration]
+
+
+
+
+NOTES
+
+
+AGASSIZ, J.L.R., naturalist, born in Switzerland, 1807; died,
+Cambridge, Mass., 1873. In 1846 he came to America, after having
+gained a high reputation in Europe, to deliver a course of lectures in
+Boston "On the Plan of the Creation," and met with such success that
+he spent the rest of his days there, declining an invitation to return
+to his native country and to Paris. In 1848 he was elected to the
+chair of Natural History at Harvard. In 1850-51 he went on an
+expedition to the Florida Reefs. In 1858 he founded and organized the
+Museum of Comparative Zoölogy at Cambridge--and, later on, went on his
+important voyage to Brazil. In 1872 he founded and organized the
+summer school of Natural History at Buzzard's Bay. He wrote "The
+Fishes of Brazil," "A Study of Glaciers," "Natural History of the
+Fresh Water Fishes of Central Europe," "Contributions to the Natural
+History of the United States" (unfinished), and with his wife, "A
+Journey in Brazil."
+
+BALL, PROF. SIR R.S., English astronomer, born in Dublin, 1840. Was
+appointed Lord Ross's astronomer in 1865. Professor of mathematics and
+mechanics at the Royal Irish College of Science in 1873, and is now
+astronomer royal for Ireland. He is the author of "The Story of the
+Heavens," "Starland," etc., and is well known as a successful lecturer
+on astronomical subjects in this country.
+
+DARWIN, CHARLES R., English naturalist, born, 1809; died, 1882. He
+first formulated what is known as the principle of Natural Selection.
+In 1831 he went in the famous scientific voyage of the _Beagle_ as
+naturalist, and afterwards published an account of it. He was one of
+the most thorough, careful, and painstaking scientific men of this or
+any age. He is the author of many famous books. "The Origin of
+Species," "The Descent of Man," "Insectivorous Plants," "The Power of
+Movement in Plants," "The Structure and Distribution of Coral Reefs,"
+"Geological Observations on Volcanic Islands." "The Formation of
+Vegetable Mould" was his last published work.
+
+FLAMMARION, C., famous French astronomer, born, 1842. He has written
+many popular works on astronomy, most of which have been translated
+into English. "The Stars," "The World Before the Creation," "Uranus,"
+"Comets," "Popular Astronomy," are among his best known.
+
+HOLDEN, PROF. E.S., American astronomer, born at St. Louis, 1846.
+Lieutenant engineers, U.S.A., 1870-73; professor mathematics, U.S.N.,
+1873-81; director Washburn Observatory, 1881-85; president University
+of California, 1883-88; director Lick Observatory, 1888-98. Is a
+member of several learned societies of Europe. Is the author of a
+"Life of William Herschel," "A Hand-book of the Lick Observatory,"
+"Earth and Sky," "Primer of Heraldry," "Elementary Astronomy," "Family
+of the Sun," "Essays in Astronomy," "Stories of the Great
+Astronomers," etc.
+
+HUXLEY, T.H., English biologist, born, 1825; died, 1895. Went on an
+exploring expedition on the _Rattlesnake_, and devoted himself to the
+study of marine life. For his scientific researches he received many
+honors. His lectures were models of clearness, and he could simplify
+the most difficult subjects. He strongly advocated Darwin's views and
+evolutionist doctrines. His writings are numerous and many of them
+technical. Among some of the most popular are "Man's Place in Nature,"
+his "Lay Sermons," "Critiques and Addresses," "American Addresses,"
+"Physiography," "Science and Culture," "Lessons in Elementary
+Physiology," etc.
+
+KINGSLEY, C., English clergyman and author, born, 1819; died, 1875.
+Wrote "Westward, Ho!" which every boy should read, "Hypatia," "Alton
+Locke," "Hereward the Wake," etc., and a charming book of travel,
+entitled, "At Last." His "Water Babies" is exceedingly popular, and
+his "Heroes" is a book much appreciated by the boys and girls alike.
+
+PROCTOR, R.A., English astronomer, born, 1834; died, 1888. He was a
+very popular writer, and lectured on astronomical subjects in this
+country, and in England and her colonies. A memorial teaching
+observatory is erected in his honor near San Diego, Cal. He was a man
+of untiring industry, an athlete, a musician, and a chess-player. His
+books are numerous. Among them are "Half Hours with the Telescope,"
+"Other Worlds than Ours," "Light Science for Leisure Hours," "The
+Expanse of Heaven," "The Moon," "The Borderland of Science," "Our
+Place Among Infinites," "Myths and Marvels of Astronomy," "The
+Universe of Suns," "Other Suns than Ours," etc.
+
+SHALER, N.S., professor of geology at Harvard. Born Newport, Ky.,
+1841. Served in the Union Army during the Civil War. Instructor
+zoölogy, geology, and paleontology, Lawrence Scientific School, till
+1887. Since then at Harvard. Is the author of "Kentucky a Pioneer
+Commonwealth," "The Story of Our Continent," "The Interpretation of
+Nature," "Feature of Coasts and Oceans," "Domesticated Animals," "The
+Individual," "Study of Life and Death," etc.
+
+THOMPSON, SIR C. WYVILLE, English zoölogist, born, 1830; died, 1882.
+He conducted scientific dredging expeditions in the _Lightning_ and
+_Porcupine_, 1868-69, and was the scientific head of the famous voyage
+of 68,900 miles in the _Challenger_ for deep-sea explorations
+(1872-76). His books are "The Depths of the Sea," and "The Voyage of
+the Challenger."
+
+TYNDALL, JOHN, English physicist, born, 1820. Began his original
+researches in 1847, when teacher of physics in Queenwood College. He
+and Professor Huxley visited the Alps together, and they wrote a work
+on the structure and nature of glaciers. It is impossible to detail
+the work he has done; but his inquiries and experiments in connection
+with light, heat, sound, and electricity have all had practical
+results. He is a popular lecturer, and devoted the proceeds of a
+lecturing tour in this country to founding scholarships at Harvard and
+Columbia Colleges, for students devoting themselves to original
+research. Among his books are "Glaciers of the Alps," "Mountaineering,"
+"Heat as a Mode of Motion," "On Radiation," "Hours of Exercise in the
+Alps," "Fragments of Science," "The Floating Matter of the Air," and
+volumes on Light, Sound, Electricity, and the forms of water.
+
+WALLACE, A.R., English naturalist and traveller, born 1822; was
+educated as land surveyor and architect, but afterwards devoted
+himself entirely to Natural History. He explored the Valley of the
+Amazon and Rio Negro, 1848-52, and travelled in the Malay Archipelago
+and Papua, 1854-62, publishing the results of his explorations later
+on. He also wrote "Contributions to the Theory of Natural Selection,"
+"Miracles and Modern Spiritualism," "Geographical Distribution of
+Animals," "Tropical Nature," "Island Life," etc.
+
+GIBERNE, AGNES, English author--living. Began to write at seven years
+old. Her first story for children was published when she was only
+seventeen. Her stories for children have not been so popular as her
+scientific writings, "Sun, Moon, and Stars," "The Starry Skies,"
+"Among the Stars," "The Ocean of Air," "The World's Foundations,"
+"Radiant Suns," etc.
+
+WILSON, ANDREW, English physiologist and lecturer, born, 1852. Is the
+author of "Studies on Life and Sense," "Leisure Time Studies,"
+"Science Stories," "Chapters on Evolution," "Wild Animals," "Brain and
+Nerve," etc., and is a constant contributor on scientific subjects to
+the magazines and newspapers, contributing weekly "Science Jottings"
+to the "Illustrated London News"
+
+
+
+
+WONDERS OF EARTH, SEA, AND SKY
+
+SUGGESTIONS FOR SUPPLEMENTARY READING
+
+
+  Wonder Stories of Science
+    D.N. BEACH
+
+  Wonders in Monsterland
+    EDWARD W.D. CUMING
+
+  Ocean Wonders
+    W.E. DAMON
+
+  Among the Stars
+    AGNES GIBERNE
+
+  The Scenery of the Heavens
+    JOHN ELLARD GORR
+
+  Coal and the Coal Miners
+    HOMER GREENE
+
+  Wonders of the Moon
+    A. GUILLEMIN
+
+  The Sea and Its Living Wonders.
+    G. HARTWIG
+
+  The Wonders of Plant Life Under the Microscope
+    SOPHIE B. HERRICK
+
+  Marvels of Animal Life
+    CHARLES F. HOLDER
+
+  Old Ocean
+    ERNEST INGERSOLL
+
+  Modern Seven Wonders of the World
+    C. KENT
+
+  Madam How and Lady Why
+    CHARLES KINGSLEY
+
+  Wonders of Optics
+    F. MARION
+
+  The Wonders of Science
+    HENRY MAYHEW
+
+  Wonders of Man and Nature
+    E. MENAULT
+
+  A Century of Electricity
+    T.C. MENDENHALL
+
+  The Orbs of Heaven
+    ORMSBY S. MITCHELL
+
+  Under Foot
+    LAURA D. NICHOLS
+
+  Myths and Marvels of Astronomy
+    R.A. PROCTOR
+
+  The Wonders of the World
+    CHARLES G. ROSENBERG
+
+  The Wonders of Nature
+    PROFESSOR RUDOLPH
+
+  Volcanoes of North America
+    ISRAEL COOK RUSSELL
+
+  Aspects of the Earth
+    N.S. SHALER
+
+  Wonders of the Bird World
+    R.B. SHARPE
+
+  The Wonders of Water
+    GASTON TISSANDIER
+
+  Total Eclipses of the Sun
+    MABEL L. TODD
+
+  Wonders of Insect Life
+    JOSEPH C. WILLET
+
+
+
+***END OF THE PROJECT GUTENBERG EBOOK YOUNG FOLKS' LIBRARY, VOLUME XI (OF
+20)***
+
+
+******* This file should be named 15884-8.txt or 15884-8.zip *******
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diff --git a/old/20050523-15884-h.htm b/old/20050523-15884-h.htm
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+<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" />
+<title>The Project Gutenberg eBook of Young Folks' Library, Volume XI (of 20), by Various</title>
+    <style type="text/css">
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+<h1>The Project Gutenberg eBook, Young Folks' Library, Volume XI (of 20), by
+Various, Edited by Edward Singleton Holden</h1>
+<pre>
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at <a href = "https://www.gutenberg.org">www.gutenberg.org</a></pre>
+<p>Title: Young Folks' Library, Volume XI (of 20)</p>
+<p>       Wonders of Earth, Sea and Sky</p>
+<p>Author: Various</p>
+<p>Editor: Edward Singleton Holden</p>
+<p>Release Date: May 23, 2005  [eBook #15884]<br />
+[Last updated: August 31, 2022]</p>
+<p>Language: English</p>
+<p>Character set encoding: ISO-8859-1</p>
+<p>***START OF THE PROJECT GUTENBERG EBOOK YOUNG FOLKS' LIBRARY, VOLUME XI (OF 20)***</p>
+<p>&nbsp;</p>
+<h3>E-text prepared by Juliet Sutherland, Sandra Brown,<br />
+    and the Project Gutenberg Online Distributed Proofreading Team</h3>
+<p>&nbsp;</p>
+<hr class="full" />
+<p>&nbsp;</p>
+<p>&nbsp;</p>
+    <span class="pagenum"><a name="pagei"
+       id="pagei"></a>[pg i]</span>
+
+    <h1>YOUNG FOLKS'<br />
+    LIBRARY</h1>
+
+    <h4>SELECTIONS FROM THE CHOICEST LITERATURE OF ALL<br />
+    LANDS; FOLK-LORE, FAIRY TALES, FABLES, LEGENDS,<br />
+    NATURAL HISTORY, WONDERS OF EARTH, SEA<br />
+    AND SKY, ANIMAL STORIES, SEA TALES,<br />
+    BRAVE DEEDS, EXPLORATIONS, STORIES<br />
+    OF SCHOOL AND COLLEGE LIFE,<br />
+    BIOGRAPHY, HISTORY, PATRIOTIC<br />
+    ELOQUENCE, POETRY</h4>
+
+    <p>&nbsp;</p>
+
+    <h3>THIRD EDITION</h3>
+
+    <h5>REVISED IN CONFERENCE BY</h5>
+
+    <h3>THOMAS BAILEY ALDRICH, EDITOR-IN-CHIEF,</h3>
+
+    <h4>PRESIDENT WILLIAM JEWETT TUCKER,<br />
+    HAMILTON WRIGHT MABIE, HENRY<br />
+    VAN DYKE, NATHAN HASKELL DOLE</h4>
+
+    <p>&nbsp;</p>
+
+    <p class="center"><i>TWENTY
+    VOLUMES&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;RICHLY
+    ILLUSTRATED</i></p>
+
+    <p>&nbsp;</p>
+
+    <h5>BOSTON<br />
+    HALL AND LOCKE COMPANY<br />
+    PUBLISHERS</h5>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="pageii"
+       id="pageii"></a>[pg ii]</span>
+
+    <h4>1902</h4>
+
+    <p>&nbsp;</p>
+
+    <h5>Stanhope Press<br />
+    F. H. GILSON COMPANY<br />
+    BOSTON, U.S.A.</h5>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="pageiii"
+       id="pageiii"></a>[pg iii]</span>
+
+    <h3>EDITORIAL BOARD</h3>
+
+    <div class="poem">
+        <div class="stanza">
+            <p><b>THOMAS BAILEY ALDRICH, Editor-in-chief,</b></p>
+
+            <p>Author, poet, former editor <i>Atlantic Monthly,</i>
+            Boston, Mass.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>The HON. JOHN D. LONG,</b></p>
+
+            <p>Secretary of the United States Navy, Boston.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>HAMILTON WRIGHT MABIE, LL.D.,</b></p>
+
+            <p>Author, literarian, associate editor <i>The
+            Outlook</i>, New York.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>ERNEST THOMPSON SETON,</b></p>
+
+            <p>Artist, author, New York.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>JOHN TOWNSEND TROWBRIDGE,</b></p>
+
+            <p>Author, poet, and editor, Arlington, Mass.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>The REVEREND CYRUS TOWNSEND BRADY,</b></p>
+
+            <p>Archdeacon, author, Philadelphia.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>JOEL CHANDLER HARRIS,</b></p>
+
+            <p>Humorous writer, Atlanta, Ga.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>MARY HARTWELL CATHERWOOD,</b></p>
+
+            <p>Historical novelist, Chicago.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>LAURA E. RICHARDS,</b></p>
+
+            <p>Author, Gardiner, Me.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>ROSWELL FIELD,</b></p>
+
+            <p>Author, editor <i>The Evening Post</i>,
+            Chicago.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>TUDOR JENKS,</b></p>
+
+            <p>Author, associate editor <i>Saint Nicholas</i>, New
+            York.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>GEORGE A. HENTY,</b></p>
+
+            <p>Traveller, author, London, England.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>KIRK MUNROE,</b></p>
+
+            <p>Writer of stories for boys, Cocoanut Grove, Fla.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>EDITH M. THOMAS,</b></p>
+
+            <p>Poet, West New Brighton, N.Y.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>CAROLINE TICKNOR,</b></p>
+
+            <p>Author, editor, Boston.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>NATHAN HASKELL DOLE,</b></p>
+
+            <p>Author, translator, literary editor <i>Current
+            History</i>, Boston.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>WILLIAM RAINEY HARPER, D.D., LL.D.,</b></p>
+
+            <p>President Chicago University.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>DAVID STARR JORDAN, M.D., LL.D.,</b></p>
+
+            <p>President Leland Stanford Junior University,
+            naturalist, writer,</p>
+
+            <p>Stanford University, Cal.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>CHARLES ELIOT NORTON, A.M., LL.D., etc.,</b></p>
+
+            <p>Scholar, author, Emeritus Professor of Art at
+            Harvard University.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>HENRY VAN DYKE, D.D., LL.D.,</b></p>
+
+            <p>Clergyman, author, Professor Princeton
+            University.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>The REVEREND THOMAS J. SHAHAN,</b></p>
+
+            <p>Dean of the Faculty of Divinity, Professor of Early
+            Ecclesiastical</p>
+
+            <p>History, Catholic University, Washington, D.C.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>WILLIAM P. TRENT,</b></p>
+
+            <p>Author, editor, Professor of English Literature,
+            Columbia University,</p>
+
+            <p>New York City.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>EDWARD SINGLETON HOLDEN, A.M., LL.D.,</b></p>
+
+            <p>Ex-president University of California, astronomer,
+            author,</p>
+
+            <p>U.S. Military Academy, West Point.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>EDWIN ERLE SPARKS,</b></p>
+
+            <p>Professor of American History, Chicago
+            University.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>The VERY REV. GEORGE M. GRANT, D.D.,
+            LL.D.,</b></p>
+
+            <p>Educator, author, vice-principal Queen's College,
+            Kingston, Ont.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>BARONESS VON BULOW,</b></p>
+
+            <p>Educator, author, Dresden, Germany.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>ABBIE FARWELL BROWN,</b></p>
+
+            <p>Author, Boston.</p>
+        </div>
+
+        <div class="stanza">
+            <p><b>CHARLES WELSH, Managing Editor,</b></p>
+
+            <p>Author, lecturer, editor, Winthrop Highlands,
+            Mass.</p>
+        </div>
+    </div><span class="pagenum"><a name="pageiv"
+       id="pageiv"></a>[pg iv]</span>
+
+    <p>&nbsp;</p>
+
+    <h3>LIST OF VOLUMES</h3>
+
+    <div class="poem">
+        <div class="stanza">
+            <p class="i16">VOLUME I.</p>
+
+            <p><b>THE STORY TELLER</b></p>
+
+            <p class="i4">Edited by CHARLES ELIOT NORTON</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME II.</p>
+
+            <p><b>THE MERRY MAKER</b></p>
+
+            <p class="i4">Edited by JOEL CHANDLER HARRIS</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME III.</p>
+
+            <p><b>FAMOUS FAIRY TALES</b></p>
+
+            <p class="i4">Edited by ROSWELL FIELD</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME IV.</p>
+
+            <p><b>TALES OF FANTASY</b></p>
+
+            <p class="i4">Edited by TUDOR JENKS</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME V.</p>
+
+            <p><b>MYTHS AND LEGENDS</b></p>
+
+            <p class="i4">Edited by THOMAS J. SHAHAN</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME VI.</p>
+
+            <p><b>THE ANIMAL STORY BOOK</b></p>
+
+            <p class="i4">Edited by ERNEST THOMPSON SETON</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME VII.</p>
+
+            <p><b>SCHOOL AND COLLEGE DAYS</b></p>
+
+            <p class="i4">Edited by KIRK MUNROE and MARY HARTWELL
+            CATHERWOOD</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME VIII.</p>
+
+            <p><b>BOOK OF ADVENTURE</b></p>
+
+            <p class="i4">Edited by NATHAN HASKELL DOLE</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME IX.</p>
+
+            <p><b>FAMOUS EXPLORERS</b></p>
+
+            <p class="i4">Edited by EDWIN ERLE SPARKS</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME X.</p>
+
+            <p><b>BRAVE DEEDS</b></p>
+
+            <p class="i4">Edited by JOHN TOWNSEND TROWBRIDGE</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME XI.</p>
+
+            <p><b>WONDERS OF EARTH, SEA AND SKY</b></p>
+
+            <p class="i4">Edited by EDWARD SINGLETON HOLDEN</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME XII.</p>
+
+            <p><b>FAMOUS TRAVELS</b></p>
+
+            <p class="i4">Edited by GEORGE A. HENTY</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME XIII.</p>
+
+            <p><b>SEA STORIES</b></p>
+
+            <p class="i4">Edited by CYRUS TOWNSEND BRADY</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME XIV.</p>
+
+            <p><b>A BOOK OF NATURAL HISTORY</b></p>
+
+            <p class="i4">Edited by DAVID STARR JORDAN</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME XV.</p>
+
+            <p><b>HISTORIC SCENES IN FICTION</b></p>
+
+            <p class="i4">Edited by HENRY VAN DYKE</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME XVI.</p>
+
+            <p><b>FAMOUS BATTLES BY LAND AND SEA</b></p>
+
+            <p class="i4">Edited by JOHN D. LONG</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME XVII.</p>
+
+            <p><b>MEN WHO HAVE RISEN</b></p>
+
+            <p class="i4">Edited by HAMILTON WRIGHT MABIE.</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME XVIII.</p>
+
+            <p><b>BOOK OF PATRIOTISM</b></p>
+
+            <p class="i4">Edited by</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME XIX.</p>
+
+            <p><b>LEADERS OF MEN, OR HISTORY TOLD IN
+            BIOGRAPHY</b></p>
+
+            <p class="i4">Edited by WILLIAM RAINEY HARPER</p>
+        </div>
+
+        <div class="stanza">
+            <p class="i16">VOLUME XX.</p>
+
+            <p><b>FAMOUS POEMS</b></p>Selected by THOMAS BAILEY
+            ALDRICH, with Poetical Foreword by EDITH M. THOMAS.
+        </div>
+    </div>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="pagevi"
+       id="pagevi"></a>[pg vi]</span>
+
+    <div class="figcenter"
+         style="width:100%;">
+        <a href="images/047.jpg"><img width="300"
+             src="images/047sm.jpg"
+             alt="A GEYSER" /></a><br />
+        A GEYSER
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="pagevii"
+       id="pagevii"></a>[pg vii]</span>
+
+    <h4><i>Young Folks' Library in Twenty Volumes</i><br />
+     <i>Thomas Bailey Aldrich, Editor-in-Chief</i></h4>
+
+    <p>&nbsp;</p>
+
+    <h1>WONDERS</h1>
+
+    <h4><span class="sc">of</span></h4>
+
+    <h1>EARTH, SEA <span class="sc">and</span> SKY</h1>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p>
+
+    <h4>EDITED BY</h4>
+
+    <h3>EDWARD SINGLETON HOLDEN</h3>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p>
+
+    <h4><i>VOLUME XI</i></h4>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p>
+
+    <div class="figcenter"
+         style="width:200px;">
+        <img width="200"
+             src="images/vii.png"
+             alt="title page decoration" />
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p>
+
+    <h5>BOSTON<br />
+    HALL AND LOCKE COMPANY<br />
+    PUBLISHERS</h5>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="pageviii"
+       id="pageviii"></a>[pg viii]</span>
+
+    <h4>1902</h4>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p>
+
+    <h5><b>Stanhope Press</b><br />
+    P.H. GILSON COMPANY<br />
+    BOSTON, U.S.A.</h5>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="pageix"
+       id="pageix"></a>[pg ix]</span>
+
+    <h2>CONTENTS</h2>
+
+    <div class="sc">
+        <div class="poem">
+            <div class="stanza"></div>
+
+            <div class="stanza">
+                <p>List of Illustrations <a href=
+                "#pagexi">&nbsp;&nbsp;xi</a></p>
+            </div>
+
+            <div class="stanza">
+                <p>The Marvels of Nature <a href=
+                "#pagexiii">&nbsp;&nbsp;xiii</a></p>
+
+                <p class="i4">By Professor E.S. Holden.</p>
+            </div>
+
+            <div class="stanza">
+                <p>what The Earth's Crust is Made of <a href=
+                "#page1">&nbsp;&nbsp;1</a></p>
+
+                <p class="i4">by Agnes Giberne.</p>
+            </div>
+
+            <div class="stanza">
+                <p>America The Old World <a href=
+                "#page45">&nbsp;&nbsp;45</a></p>
+
+                <p class="i4">By Louis Agassiz.</p>
+            </div>
+
+            <div class="stanza">
+                <p>Some Records of the Rocks <a href=
+                "#page77">&nbsp;&nbsp;77</a></p>
+
+                <p class="i4">By N.S. Shaler.</p>
+            </div>
+
+            <div class="stanza">
+                <p>The Pitch Lake in the West Indies <a href=
+                "#page97">&nbsp;&nbsp;97</a></p>
+
+                <p class="i4">By Charles Kingsley.</p>
+            </div>
+
+            <div class="stanza">
+                <p>A Stalagmite Cave <a href=
+                "#page111">&nbsp;&nbsp;111</a></p>
+
+                <p class="i4">By Sir C. Wyville Thomson.</p>
+            </div>
+
+            <div class="stanza">
+                <p>The Big Trees of California <a href=
+                "#page119">&nbsp;&nbsp;119</a></p>
+
+                <p class="i4">by Alfred Russel Wallace.</p>
+            </div>
+
+            <div class="stanza">
+                <p>what is Evolution? <a href=
+                "#page127">&nbsp;&nbsp;127</a></p>
+
+                <p class="i4">By Professor Edward S. Holden.</p>
+            </div>
+
+            <div class="stanza">
+                <p>How the Soil is Made <a href=
+                "#page135">&nbsp;&nbsp;135</a></p>
+
+                <p class="i4">By Charles Darwin.</p>
+            </div>
+
+            <div class="stanza">
+                <p>Zoölogical Myths <a href=
+                "#page143">&nbsp;&nbsp;143</a></p>
+
+                <p class="i4">By Andrew Wilson.</p>
+            </div>
+
+            <div class="stanza">
+                <p>On a Piece of Chalk <a href=
+                "#page171">&nbsp;&nbsp;171</a></p>
+
+                <p class="i4">By T.H. Huxley.</p>
+            </div>
+
+            <div class="stanza">
+                <p>A Bit of Sponge <a href=
+                "#page205">&nbsp;&nbsp;205</a></p>
+
+                <p class="i4">BY A. WILSON.</p>
+            </div>
+
+            <div class="stanza">
+                <p>The Greatest Sea-Wave Ever Known <a href=
+                "#page211">&nbsp;&nbsp;211</a></p>
+
+                <p class="i4">By R.A. Proctor.</p><span class=
+                "pagenum"><a name="pagex"
+                   id="pagex"></a>[pg x]</span>
+            </div>
+
+            <div class="stanza">
+                <p>The Phosphorescent Sea <a href=
+                "#page228">&nbsp;&nbsp;228</a></p>
+
+                <p class="i4">By W.S. Dallas.</p>
+            </div>
+
+            <div class="stanza">
+                <p>COMETS, <a href=
+                "#page251">&nbsp;&nbsp;251</a></p>
+
+                <p class="i4">By Camille Flammarion.</p>
+            </div>
+
+            <div class="stanza">
+                <p>The Total Solar Eclipse of 1883 <a href=
+                "#page261">&nbsp;&nbsp;261</a></p>
+
+                <p class="i4">By E.S. Holden.</p>
+            </div>
+
+            <div class="stanza">
+                <p>Halos&mdash;Parhelia&mdash;the Spectre of the
+                Brocken, etc. <a href=
+                "#page268">&nbsp;&nbsp;268</a></p>
+
+                <p class="i4">By Camille Flammarion.</p>
+            </div>
+
+            <div class="stanza">
+                <p>The Planet Venus <a href=
+                "#page282">&nbsp;&nbsp;282</a></p>
+
+                <p class="i4">By Agnes M. Clerke.</p>
+            </div>
+
+            <div class="stanza">
+                <p>The Stars <a href=
+                "#page296">&nbsp;&nbsp;296</a></p>
+
+                <p class="i4">By Sir R.S. Ball.</p>
+            </div>
+
+            <div class="stanza">
+                <p>Rain and Snow <a href=
+                "#page342">&nbsp;&nbsp;342</a></p>
+
+                <p class="i4">By John Tyndall.</p>
+            </div>
+
+            <div class="stanza">
+                <p>The Organic World <a href=
+                "#page357">&nbsp;&nbsp;357</a></p>
+
+                <p class="i4">By St. George Mivart.</p>
+            </div>
+
+            <div class="stanza">
+                <p>Inhabitants of My Pool <a href=
+                "#page366">&nbsp;&nbsp;366</a></p>
+
+                <p class="i4">By Arabella B. Buckley.</p>
+            </div>
+
+            <div class="stanza">
+                <p>Biographical Notes <a href=
+                "#page387">&nbsp;&nbsp;387</a></p>
+            </div>
+
+            <div class="stanza">
+                <p>Suggestions for Supplementary Reading
+                   <a href="#page389">&nbsp;&nbsp;389</a></p>
+            </div>
+        </div>
+    </div>
+
+    <h5>NOTE.</h5>
+
+    <p>The publishers' acknowledgments are due to Messrs. Houghton,
+    Mifflin &amp; Co., for permission to use "America and the Old
+    World," by L. Agassiz; to Messrs. D.C. Heath &amp; Co. for
+    permission to use "Some Records of the Rocks," by Professor
+    N.S. Shaler; and to Professor E.S. Holden for permission to use
+    "What is Evolution?" and "An Astronomer's Voyage to Fairy
+    Land."</p>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="pagexi"
+       id="pagexi"></a>[pg xi]</span>
+
+    <h2>LIST OF COLORED ILLUSTRATIONS</h2>
+    <hr class="short" />
+
+    <div class="poem">
+        <div class="stanza">
+            <p><span class="sc">A Geyser.</span>&nbsp;&nbsp;
+            <a href="#pagevi"><i>Frontispiece,</i></a> <i>See
+            Page</i> <a href="#page47">&nbsp;&nbsp;47</a></p>
+        </div>
+
+        <div class="stanza">
+            <p class="sc">View in a Cañon, <a href=
+            "#page12">&nbsp;&nbsp;12</a></p>
+        </div>
+
+        <div class="stanza">
+            <p class="sc">A Volcano, <a href=
+            "#page48">&nbsp;&nbsp;48</a></p>
+        </div>
+
+        <div class="stanza">
+            <p class="sc">A Stalagmite Cave, <a href=
+            "#page117">&nbsp;&nbsp;117</a></p>
+        </div>
+
+        <div class="stanza">
+            <p class="sc">Where Sponges Grow, <a href=
+            "#page209">&nbsp;&nbsp;209</a></p>
+        </div>
+
+        <div class="stanza">
+            <p class="sc">A Comet, <a href=
+            "#page254">&nbsp;&nbsp;254</a></p>
+        </div>
+
+        <div class="stanza">
+            <p class="sc">The Spectre Of The Brocken, <a href=
+            "#page272">&nbsp;&nbsp;272</a></p>
+        </div>
+    </div>
+    <hr class="short" />
+
+    <p class="sc">And One Hundred and Sixty-four Black and White
+    Illustrations in the Text.</p>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="pagexiii"
+       id="pagexiii"></a>[pg xiii]</span>
+
+    <h2>THE MARVELS OF NATURE</h2>
+
+    <h4 class="sc">By</h4>
+
+    <h3>EDWARD S. HOLDEN, M.A., Sc.D. LL.D.</h3>
+    <hr class="short" />
+
+    <p>The Earth, the Sea, the Sky, and their wonders&mdash;these
+    are the themes of this volume. The volume is so small, and the
+    theme so vast! Men have lived on the earth for hundreds of thousands
+    of years; and its wonders have increased, not diminished,
+    with their experience.</p>
+
+    <p>To our barbarous ancestors of centuries ago, all was
+    mystery&mdash;the thunder, the rainbow, the growing corn, the
+    ocean, the stars. Gradually and by slow steps they learned to
+    house themselves in trees, in caves, in huts, in houses; to
+    find a sure supply of food; to provide a stock of serviceable
+    clothing. The arts of life were born; tools were invented; the
+    priceless boon of fire was received; tribes and clans united
+    for defence; some measure of security and comfort was
+    attained.</p>
+
+    <p>With security and comfort came leisure; and the mind of
+    early Man began curiously to inquire the meaning of the
+    mysteries with which he was surrounded. That curious inquiry
+    was the birth of Science. Art was born when some far-away
+    ancestor, in an idle hour, <span class="pagenum"><a name=
+    "pagexiv"
+       id="pagexiv"></a>[pg xiv]</span> scratched on a bone the
+       drawing of two of his reindeer fighting, or carved on the
+       walls of his cave the image of the mammoth that he had but
+       lately slain with his spear and arrows.</p>
+
+    <p>In a mind that is completely ignorant there is no wonder.
+    Wonder is the child of knowledge&mdash;of partial and imperfect
+    knowledge, to be sure, but still, of knowledge. The very first
+    step in Science is to make an inventory of external Nature (and
+    by and by of the faculties of the mind that thinks). The second
+    step is to catalogue similar appearances together. It is a much
+    higher flight to seek the causes of likenesses thus
+    discovered.</p>
+
+    <p>A few of the chapters of this volume are items in a mere
+    catalogue of wonders, and deserve their place by accurate and
+    eloquent description. Most of them, however, represent higher
+    stages of insight. In the latter, Nature is viewed not only
+    with the eye of the observer, but also with the mind's eye,
+    curious to discover the reasons for things seen. The most
+    penetrating inward inquiry accompanies the acutest external
+    observation in such chapters as those of Darwin and Huxley,
+    here reprinted.</p>
+
+    <p>Now, the point not to be overlooked is this: to Darwin and
+    Huxley, as to their remote and uncultured ancestors, the
+    World&mdash;the Earth, the Sea, the Sky&mdash;is full of
+    wonders and of mysteries, but the wonders are of a higher
+    order. The problems of the thunder <span class=
+    "pagenum"><a name="pagexv"
+       id="pagexv"></a>[pg xv]</span> and of the rainbow as they
+       presented themselves to the men of a thousand generations
+       ago, have been fully solved: but the questions; what is the
+       veritable nature of electricity, exactly how does it differ
+       from light, are still unanswered. And what are simple
+       problems like these to the questions: what is love; why do
+       we feel a sympathy with this person, an antipathy for that;
+       and others of the sort? Science has made almost infinite
+       advances since pre-historic man first felt the feeble
+       current of intellectual curiosity amid his awe of the storm;
+       it has still to grow almost infinitely before anything like
+       a complete explanation even of external Nature is
+       achieved.</p>
+
+    <p>Suppose that, at some future day, all physical and
+    mechanical laws should be found to be direct consequences of a
+    single majestic law, just as all the motions of the planets are
+    (but&mdash;are they?) the direct results of the single law of
+    gravitation. Gravitation will, probably, soon be explained in
+    terms of some remoter cause, but the reason of that single and
+    ultimate law of the universe which we have imagined would still
+    remain unknown. Human knowledge will always have limits, and
+    beyond those limits there will always be room for mystery and
+    wonder. A complete and exhaustive explanation of the world is
+    inconceivable, so long as human powers and capacities remain at
+    all as they now are.</p>
+
+    <p>It is important to emphasize such truths, especially
+    <span class="pagenum"><a name="pagexvi"
+       id="pagexvi"></a>[pg xvi]</span> in a book addressed to the
+       young. When a lad hears for the first time that an
+       astronomer, by a simple pointing of his spectroscope, can
+       determine with what velocity a star is approaching the
+       earth, or receding from it, or when he hears that the very
+       shape of the revolving masses of certain stars can be
+       calculated from simple measures of the sort, he is apt to
+       conclude that Science, which has made such astounding
+       advances since the days of Galileo and Newton, must
+       eventually reach a complete explanation of the entire
+       universe. The conclusion is not unnatural, but it is not
+       correct. There are limits beyond which Science, in this
+       sense, cannot go. Its scope is limited. Beyond its limits
+       there are problems that it cannot solve, mysteries that it
+       cannot explain.</p>
+
+    <p>At the present moment, for example, the nature of Force is
+    unknown. A weight released from the hand drops to the earth.
+    Exactly what is the nature of the force with which the earth
+    attracts it? We do not know, but it so happens that it is more
+    than likely that an explanation will be reached in our own day.
+    Gravity will be explained in terms of some more general forces.
+    The mystery will be pushed back another step, and yet another
+    and another. But the progress is not indefinite. If all the
+    mechanical actions of the entire universe were to be formulated
+    as the results of a single law or cause, the cause of that
+    cause would be still to seek, as has been
+          said.</p><span class="pagenum"><a name="pagexvii"
+       id="pagexvii"></a>[pg xvii]</span>
+
+    <p>We have every right to exult in the amazing achievements of
+    Science; but we have not understood them until we realize that
+    the universe of Science has strict limits, within which all its
+    conquests must necessarily be confined. Humility, and not
+    pride, is the final lesson of scientific work and study.</p>
+    <hr />
+
+    <p>The choice of the selections printed in this volume has been
+    necessarily limited by many hampering conditions, that of mere
+    space being one of the most harassing. Each of the chapters
+    might readily be expanded into a volume. Volumes might be added
+    on topics almost untouched here. It has been necessary to pass
+    over almost without notice matters of surpassing interest and
+    importance: Electricity and its wonderful and new applications;
+    the new Biology, with its views upon such fundamental questions
+    as the origins of life and death; modern Astronomy, with its
+    far-reaching pronouncements upon the fate of universes. All
+    these can only be touched lightly, if at all. It is the chief
+    purpose of this volume to point the way towards the most modern
+    and the greatest conclusions of Science, and to lay foundations
+    upon which the reading of a life-time can be laid.</p>
+
+    <div class="figright"
+         style="width:300px;">
+        <img width="300"
+             src="images/xvii.png"
+             alt="signature" />
+    </div><br clear="all" />
+
+    <p><span class="sc">United States Military Academy,<br />
+     &nbsp;&nbsp;&nbsp;&nbsp;West Point,</span> <i>January 1,
+    1902</i>.</p>
+    <hr />
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="page1"
+       id="page1"></a>[pg 1]</span>
+
+    <h1>WONDERS OF EARTH, SEA, AND SKY</h1>
+    <hr class="short" />
+
+    <h2>WHAT THE EARTH'S CRUST IS MADE OF</h2>
+
+    <h4 class="sc">(From The World's Foundations.)</h4>
+
+    <h3><span class="sc">By</span> AGNES GIBERNE.</h3>
+    <hr class="short" />
+
+    <blockquote>
+        <p>"Stand still and consider the wondrous works of
+        God."</p>
+    </blockquote>
+
+    <div class="figleft"
+         style="width:200px">
+        <a href="images/001.png"><img width="200"
+             src="images/001.png"
+             alt="globe" /></a>
+    </div>
+
+    <p>What is the earth made of&mdash;this round earth upon which
+    we human beings live and move?</p>
+
+    <p>A question more easily asked than answered, as regards a
+    very large portion of it. For the earth is a huge ball nearly
+    eight thousand miles in diameter, and we who dwell on the
+    outside have no means of getting down more than a very little
+    way below the surface. So it is quite impossible for us to
+    speak positively as to the inside of the earth, and what it is
+    made of. Some people believe the earth's inside to be hard and
+    solid, while others believe it to be one <span class=
+    "pagenum"><a name="page2"
+       id="page2"></a>[pg 2]</span> enormous lake or furnace of
+       fiery melted rock. But nobody really knows.</p>
+
+    <p>This outside crust has been reckoned to be of many different
+    thicknesses. One man will say it is ten miles thick, and
+    another will rate it at four hundred miles. So far as regards
+    man's knowledge of it, gained from mining, from boring, from
+    examination of rocks, and from reasoning out all that may be
+    learned from these observations, we shall allow an ample margin
+    if we count the field of geology to extend some twenty miles
+    downwards from the highest mountain-tops. Beyond this we find
+    ourselves in a land of darkness and conjecture.</p>
+
+    <p>Twenty miles is only one four-hundredth part of the earth's
+    diameter&mdash;a mere thin shell over a massive globe. If the
+    earth were brought down in size to an ordinary large school
+    globe, a piece of rough brown paper covering it might well
+    represent the thickness of this earth-crust, with which the
+    science of geology has to do. And the whole of the globe, this
+    earth of ours, is but one tiny planet in the great Solar
+    System. And the centre of that Solar System, the blazing sun,
+    though equal in size to more than a million earths, is yet
+    himself but one star amid millions of twinkling stars,
+    scattered broadcast through the universe. So it would seem at
+    first sight that the field of geology is a small field compared
+    with that of astronomy....</p>
+
+    <p>With regard to the great bulk of the globe little can be
+    said. Very probably it is formed through and through of the
+    same materials as the crust. This we do not know. Neither can
+    we tell, even if it be so formed, whether the said materials
+    are solid and cold <span class="pagenum"><a name="page3"
+       id="page3"></a>[pg 3]</span> like the outside crust, or
+       whether they are liquid with heat. The belief has been long
+       and widely held that the whole inside of the earth is one
+       vast lake or furnace of melted fiery-hot material, with only
+       a thin cooled crust covering it. Some in the present day are
+       inclined to question this, and hold rather that the earth is
+       solid and cold throughout, though with large lakes of liquid
+       fire here and there, under or in her crust, from which our
+       volcanoes are fed....</p>
+
+    <p>The materials of which the crust is made are many and
+    various; yet, generally speaking, they may all be classed under
+    one simple word, and that word is&mdash;<i>Rock</i>.</p>
+
+    <p>It must be understood that, when we talk of rock in this
+    geological sense, we do not only mean hard and solid stone, as
+    in common conversation. Rock may be changed by heat into a
+    liquid or "molten" state, as ice is changed by heat to water.
+    Liquid rock may be changed by yet greater heat to vapor, as
+    water is changed to steam, only we have in a common way no such
+    heat at command as would be needed to effect this. Rock may be
+    hard or soft. Rock maybe chalky, clayey, or sandy. Rock may be
+    so close-grained that strong force is needed to break it; or it
+    may be so porous&mdash;so full of tiny holes&mdash;that water
+    will drain through it; or it may be crushed and crumbled into
+    loose grains, among which you can pass your fingers.</p>
+
+    <p>The cliffs above our beaches are rock; the sand upon our
+    seashore is rock; the clay used in brick-making is rock; the
+    limestone of the quarry is rock; the marble of which our
+    mantel-pieces are made is rock. The soft sandstone of South
+    Devon, and the hard granite of the <span class=
+    "pagenum"><a name="page4"
+       id="page4"></a>[pg 4]</span> north of Scotland, are alike
+       rock. The pebbles in the road are rock; the very mould in
+       our gardens is largely composed of crumbled rock. So the
+       word in its geological sense is a word of wide meaning.</p>
+
+    <p>Now the business of the geologist is to read the history of
+    the past in these rocks of which the earth's crust is made.
+    This may seem a singular thing to do, and I can assure you it
+    is not an easy task.</p>
+
+    <p>For, to begin with, the history itself is written in a
+    strange language, a language which man is only just beginning
+    to spell out and understand. And this is only half the
+    difficulty with which we have to struggle.</p>
+
+    <p>If a large and learned book were put before you and you were
+    set to read it through, you would perhaps, have no
+    insurmountable difficulty, with patience and perseverance, in
+    mastering its meaning.</p>
+
+    <p>But how if the book were first chopped up into pieces, if
+    part of it were flung away out of reach, if part of it were
+    crushed into a pulp, if the numbering of the pages were in many
+    places lost, if the whole were mixed up in confusion, and if
+    <i>then</i> you were desired to sort, and arrange, and study
+    the volume?</p>
+
+    <p>Picture to yourself what sort of a task this would be, and
+    you will have some idea of the labors of the patient
+    geologist.</p>
+
+    <p>Rocks may be divided into several kinds or classes. For the
+    present moment it will be enough to consider the two grand
+    divisions&mdash;<i>Stratified rocks</i> and <i>Unstratified
+    rocks</i>.</p>
+
+    <p>Unstratified rocks are those which were once, at a time more
+    or less distant, in a melted state from intense heat, and which
+    have since cooled into a half <i>crystalized</i>
+          <span class="pagenum"><a name="page5"
+       id="page5"></a>[pg 5]</span> state; much the same as water,
+       when growing colder, cools and crystallizes into ice.
+       Strictly speaking, ice is rock, just as much as granite and
+       sandstone are rock. Water itself is of the nature of rock,
+       only as we commonly know it in the liquid state we do not
+       commonly call it so.</p>
+
+    <div class="figright"
+         style="width:400px;">
+        <a href="images/005.png"><img width="400"
+             src="images/005.png"
+             alt=
+             "UNSTRATIFIED ROCK.&mdash;A VOLCANIC BLOCK." /></a><br />
+        UNSTRATIFIED ROCK.&mdash;A VOLCANIC BLOCK.
+    </div>
+
+    <p>"Crystallization" means those particular forms or shapes in
+    which the particles of a liquid arrange themselves, as that
+    liquid hardens into a solid&mdash;in other words, as it
+    freezes. Granite, iron, marble, are frozen substances, just as
+    truly as ice is a frozen substance; for with greater heat they
+    would all become liquid like water. When a liquid freezes,
+    there are always crystals formed, though these are not always
+    visible without the help of a microscope. Also the crystals are
+    of different shapes with different substances.</p>
+
+    <p>If you examine the surface of a puddle or pond, when a thin
+    covering of ice is beginning to form, you will be able to see
+    plainly the delicate sharp needle-like forms of the ice
+    crystals. Break a piece of ice, and you will find that it will
+    not easily break just in any way that you may choose, but it
+    will only split along the lines of these needle-like crystals.
+    This particular mode of splitting in a crystallized rock is
+    called the <i>cleavage</i> of that rock.</p>
+
+    <p>Crystallization may take place either slowly or
+          <span class="pagenum"><a name="page6"
+       id="page6"></a>[pg 6]</span> rapidly, and either in the open
+       air or far below ground. The lava from a volcano is an
+       example of rock which has crystallized rapidly in the open
+       air; and granite is an example of rock which has
+       crystallized slowly underground beneath great pressure.</p>
+
+    <p>Stratified rocks, on the contrary, which make up a very
+    large part of the earth's crust, are not crystallized. Instead
+    of having cooled from a liquid into a solid state, they have
+    been slowly <i>built up</i>, bit by bit and grain upon grain,
+    into their present form, through long ages of the world's
+    history. The materials of which they are made were probably
+    once, long, long ago, the crumblings from granite and other
+    crystallized rocks, but they show now no signs of
+    crystallization.</p>
+
+    <div class="figleft"
+         style="width:300px">
+        <a href="images/006.png"><img width="300"
+             src="images/006.png"
+             alt="SECTION OF STRATIFIED ROCKS." /></a><br />
+        SECTION OF STRATIFIED ROCKS.
+
+        <p><i>a.</i> Conglomerate. <i>b.</i> Pebbly Sandstone,
+        <i>c.</i> Thin-bedded Sandstone, <i>d.</i> Shelly
+        Sandstone, <i>e.</i> Shale. <i>f.</i> Limestone.</p>
+    </div>
+
+    <p>They are called "stratified" because they are in themselves
+    made up of distinct layers, and also because they lie thus one
+    upon another in layers, or <i>strata</i>, just as the leaves of
+    a book lie, or as the bricks of a house are placed.</p>
+
+    <p>Throughout the greater part of Europe, of Asia, of Africa,
+    of North and South America, of Australia, these rocks are to be
+    found, stretching over hundreds <span class=
+       "pagenum"><a name="page7"
+       id="page7"></a>[pg 7]</span> of miles together, north,
+       south, east, and west, extending up to the tops of some of
+       the earth's highest mountains, reaching down deep into the
+       earth's crust. In many parts if you could dig straight
+       downwards through the earth for thousands of feet, you would
+       come to layer after layer of these stratified rocks, one
+       kind below another, some layers thick, some layers thin,
+       here a stratum of gravel, there a stratum of sandstone, here
+       a stratum of coal, there a stratum of clay.</p>
+
+    <p>But how, when, where, did the building up of all these
+    rock-layers take place?</p>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/007.png"><img width="600"
+             src="images/007.png"
+             alt=
+             "THE BEACH IN THE FOREGROUND IS A ROCKY SHELF," /></a>
+
+        <p>THE BEACH IN THE FOREGROUND IS A ROCKY SHELF, THE
+        REMNANT OF THE CLIFF WHICH ONCE EXTENDED OUT TO THE
+        ISLAND.</p>
+    </div>
+
+    <p>People are rather apt to think of land and water on the
+    earth as if they were fixed in one changeless form,&mdash;as if
+    every continent and every island were of exactly the same shape
+    and size now that it always has been and always will
+    be.</p><span class="pagenum"><a name="page8"
+       id="page8"></a>[pg 8]</span>
+
+    <p>Yet nothing can be further from the truth. The earth-crust
+    is a scene of perpetual change, of perpetual struggle, of
+    perpetual building up, of perpetual wearing away.</p>
+
+    <p>The work may go on slowly, but it does go on. The sea is
+    always fighting against the land, beating down her cliffs,
+    eating into her shores, swallowing bit by bit of solid earth;
+    and rain and frost and inland streams are always busily at
+    work, helping the ocean in her work of destruction. Year by
+    year and century by century it continues. Not a country in the
+    world which is bordered by the open sea has precisely the same
+    coast-line that it had one hundred years ago; not a land in the
+    world but parts each century with masses of its material,
+    washed piecemeal away into the ocean.</p>
+
+    <p>Is this hard to believe? Look at the crumbling cliffs around
+    old England's shores. See the effect upon the beach of one
+    night's fierce storm. Mark the pathway on the cliff, how it
+    seems to have crept so near the edge that here and there it is
+    scarcely safe to tread; and very soon, as we know, it will
+    become impassable. Just from a mere accident, of
+    course,&mdash;the breaking away of some of the earth, loosened
+    by rain and frost and wind. But this is an accident which
+    happens daily in hundreds of places around the shores.</p>
+
+    <p>Leaving the ocean, look now at this river in our
+    neighborhood, and see the slight muddiness which seems to color
+    its waters. What from? Only a little earth and sand carried off
+    from the banks as it flowed,&mdash;very unimportant and small
+    in quantity, doubtless, just at this moment and just at this
+    spot. But what of that little going on week after week, and
+    century <span class="pagenum"><a name="page9"
+       id="page9"></a>[pg 9]</span> after century, throughout the
+       whole course of the river, and throughout the whole course
+       of every river and rivulet in our whole country and in every
+       other country. A vast amount of material must every year be
+       thus torn from the land and given to the ocean. For the
+       land's loss here is the ocean's gain.</p>
+
+    <p>And, strange to say, we shall find that this same ocean, so
+    busily engaged with the help of its tributary rivers in pulling
+    down land, is no less busily engaged with their help in
+    building it up.</p>
+
+    <p>You have sometimes seen directions upon a vial of medicine
+    to "shake" before taking the dose. When you have so shaken the
+    bottle the clear liquid grows thick; and if you let it stand
+    for awhile the thickness goes off, and a fine grain-like or
+    dust-like substance settles down at the bottom&mdash;the
+    settlement or <i>sediment</i> of the medicine. The finer this
+    sediment, the slower it is in settling. If you were to keep the
+    liquid in gentle motion, the fine sediment would not settle
+    down at the bottom. With coarser and heavier grains the motion
+    would have to be quicker to keep them supported in the
+    water.</p>
+
+    <p>Now it is just the same thing with our rivers and streams.
+    Running water can support and carry along sand and earth, which
+    in still water would quickly sink to the bottom; and the more
+    rapid the movement of the water, the greater is the weight it
+    is able to bear.</p>
+
+    <p>This is plainly to be seen in the case of a mountain
+    torrent. As it foams fiercely through its rocky bed it bears
+    along, not only mud and sand and gravel, but stones and even
+    small rocks, grinding the latter roughly together till they are
+    gradually worn away, first to <span class="pagenum"><a name=
+    "page10"
+       id="page10"></a>[pg 10]</span> rounded pebbles, then to
+       sand, and finally to mud. The material thus swept away by a
+       stream, ground fine, and carried out to sea&mdash;part being
+       dropped by the way on the river-bed&mdash;is called
+       <i>detritus</i>, which simply means <i>worn-out</i>
+       material.</p>
+
+    <div class="figleft"
+         style="width:400px;">
+        <a href="images/010.png"><img width="400"
+             src="images/010.png"
+             alt="A MOUNTAIN TORRENT." /></a><br />
+        A MOUNTAIN TORRENT.
+    </div>
+
+    <p>The tremendous carrying-power of a mountain torrent can
+    scarcely be realized by those who have not observed it for
+    themselves. I have seen a little mountain-stream swell in the
+    course of a heavy thunderstorm to such a torrent, brown and
+    turbid with earth torn from the mountainside, and sweeping
+    resistlessly along in its career a shower of stones and
+    rock-fragments. That which happens thus occasionally with many
+    streams is more or less the work all the year round of many
+    more.</p>
+
+    <p>As the torrent grows less rapid, lower down in its course,
+    it ceases to carry rocks and stones, though the grinding and
+    wearing away of stones upon the rocky bed continues, and coarse
+    gravel is borne still upon its <span class=
+       "pagenum"><a name="page11"
+       id="page11"></a>[pg 11]</span> waters. Presently the
+       widening stream, flowing yet more calmly, drops upon its bed
+       all such coarser gravel as is not worn away to fine earth,
+       but still bears on the lighter grains of sand. Next the
+       slackening speed makes even the sand too heavy a weight, and
+       that in turn falls to line the river-bed, while the now
+       broad and placid stream carries only the finer particles of
+       mud suspended in its waters. Soon it reaches the ocean, and
+       the flow being there checked by the incoming ocean-tide,
+       even the mud can no longer be held up, and it also sinks
+       slowly in the shallows near the shore, forming sometimes
+       broad mud-banks dangerous to the mariner.</p>
+
+    <p>This is the case only with smaller rivers. Where the stream
+    is stronger, the mud-banks are often formed much farther out at
+    sea; and more often still the river-detritus is carried away
+    and shed over the ocean-bed, beyond the reach of our ken. The
+    powerful rush of water in earth's greater streams bears
+    enormous masses of sand and mud each year far out into the
+    ocean, there dropping quietly the gravel, sand, and earth,
+    layer upon layer at the bottom of the sea. Thus pulling down
+    and building up go on ever side by side; and while land is the
+    theatre oftentimes of decay and loss, ocean is the theatre
+    oftentimes of renewal and gain.</p>
+
+    <p>Did you notice the word "sediment" used a few pages back
+    about the settlement at the bottom of a medicine-vial?</p>
+
+    <p>There is a second name given to the Stratified Rocks, of
+    which the earth's crust is so largely made up. They are called
+    also <i>Sedimentary Rocks</i>.</p><span class=
+       "pagenum"><a name="page12"
+       id="page12"></a>[pg 12]</span>
+
+    <p>The reason is simply this. The Stratified Rocks of the
+    present day were once upon a time made up out of the sediment
+    stolen first from land and then allowed to settle down on the
+    sea-bottom.</p>
+
+    <p>Long, long ago, the rivers, the streams, the ocean, were at
+    work, as they are now, carrying away rock and gravel, sand and
+    earth. Then, as now, all this material, borne upon the rivers,
+    washed to and fro by the ocean, settled down at the mouths of
+    rivers or at the bottom of the sea, into a sediment, one layer
+    forming over another, gradually built up through long ages. At
+    first it was only a soft, loose, sandy or muddy sediment, such
+    as you may see on the seashore, or in a mud-bank. But as the
+    thickness of the sediment increased, the weight of the layers
+    above gradually pressed the lower layers into firm hard rocks;
+    and still, as the work of building went on, these layers were,
+    in their turn, made solid by the increasing weight over them.
+    Certain chemical changes had also a share in the transformation
+    from soft mud to hard rock, which need not be here
+    considered.</p>
+
+    <p>All this has through thousands of years been going on. The
+    land is perpetually crumbling away; and fresh land under the
+    sea is being perpetually built up, from the very same materials
+    which the sea and the rivers have so mercilessly stolen from
+    continents and islands. This is the way, if geologists rightly
+    judge, in which a very large part of the enormous formations of
+    Stratified or Sedimentary Rocks have been made.</p>
+
+    <div class="figcenter"
+         style="width:300px;">
+        <a href="images/031.jpg"><img width="300"
+             src="images/031sm.jpg"
+             alt="VIEW IN A CANON." /></a><br />
+        VIEW IN A CANON.
+    </div>
+
+    <p>So far is clear. But now we come to a difficulty.</p>
+
+    <p>The Stratified Rocks, of which a very large part of the
+    continents is made, appear to have been built up
+          <span class="pagenum"><a name="page13"
+       id="page13"></a>[pg 13]</span> slowly, layer upon layer, out
+       of the gravel, sand, and mud, washed away from the land and
+       dropped on the shore of the ocean.</p>
+
+    <div class="figright"
+         style="width:400px;">
+        <a href="images/013.png"><img width="400"
+             src="images/013.png"
+             alt=
+           "SEA CLIFFS SHOWING A SERIES OF STRATIFIED ROCKS." /></a><br />
+        SEA CLIFFS SHOWING A SERIES OF STRATIFIED ROCKS.
+    </div>
+
+    <p>You may see these layers for yourself as you walk out into
+    the country. Look at the first piece of bluff rock you come
+    near, and observe the clear pencil-like markings of layer above
+    layer&mdash;not often indeed lying <i>flat</i>, one over
+    another, and this must be explained later, but however
+    irregularly slanting, still plainly visible. You can examine
+    these lines of stratification on the nearest cliff, the nearest
+    quarry, the nearest bare headland, in your neighborhood.</p>
+
+    <p>But how can this be? If all these stratified rocks are built
+    on the floor of the ocean out of material taken <i>from</i> the
+    land, how can we by any possibility find such rocks <i>upon</i>
+    the land? In the beds of rivers we might indeed expect to see
+    them, but surely nowhere else save under ocean waters.</p>
+
+    <p>Yet find them we do. Through England, through the two great
+    world-continents, they abound on every side. Thousands of miles
+    in unbroken succession are composed of such rocks.</p>
+
+    <p>Stand with me near the seashore, and let us look around.
+    Those white chalk cliffs&mdash;they, at least, are
+          <span class="pagenum"><a name="page14"
+       id="page14"></a>[pg 14]</span> not formed of sand or earth.
+       True, and the lines of stratification are in them very
+       indistinct, if seen at all; yet they too are built up of
+       sediment of a different kind, dropping upon ocean's floor.
+       See, however, in the rough sides of yonder bluff the
+       markings spoken of, fine lines running alongside of one
+       another, sometimes flat, sometimes bent or slanting, but
+       always giving the impression of layer piled upon layer. Yet
+       how can one for a moment suppose that the ocean-waters ever
+       rose so high?</p>
+
+    <p>Stay a moment. Look again at yonder white chalk cliff, and
+    observe a little way below the top a singular band of shingles,
+    squeezed into the cliff, as it were, with chalk below and earth
+    above.</p>
+
+    <p>That is believed to be an old sea-beach. Once upon a time
+    the waters of the sea are supposed to have washed those
+    shingles, as now they wash the shore near which we stand, and
+    all the white cliff must have lain then beneath the ocean.</p>
+
+    <p>Geologists were for a long while sorely puzzled to account
+    for these old sea-beaches, found high up in the cliffs around
+    our land in many different places.</p>
+
+    <p>They had at first a theory that the sea must once, in far
+    back ages, have been a great deal higher than it is now. But
+    this explanation only brought about fresh difficulties. It is
+    quite impossible that the level of the sea should be higher in
+    one part of the world than in another. If the sea around
+    England were then one or two hundred feet higher than it is
+    now, it must have been one or two hundred feet higher in every
+    part of the world where the ocean-waters have free flow. One is
+    rather puzzled to know where all the <span class=
+    "pagenum"><a name="page15"
+       id="page15"></a>[pg 15]</span> water could have come from,
+       for such a tremendous additional amount. Besides, in some
+       places remains of sea-animals are found in mountain heights,
+       as much as two or three thousand feet above the
+       sea-level&mdash;as, for instance, in Corsica. This very much
+       increases the difficulty of the above explanation.</p>
+
+    <p>So another theory was started instead, and this is now
+    generally supposed to be the true one. What if instead of the
+    whole ocean having been higher, parts of the land were lower?
+    England at one time, parts of Europe at another time, parts of
+    Asia and America at other times, may have slowly sunk beneath
+    the ocean, and after long remaining there have slowly risen
+    again.</p>
+
+    <p>This is by no means so wild a supposition as it may seem
+    when first heard, and as it doubtless did seem when first
+    proposed. For even in the present day these movements of the
+    solid crust of our earth are going on. The coasts of Sweden and
+    Finland have long been slowly and steadily rising out of the
+    sea, so that the waves can no longer reach so high upon those
+    shores as in years gone by they used to reach. In Greenland, on
+    the contrary, land has long been slowly and steadily sinking,
+    so that what used to be the shore now lies under the sea. Other
+    such risings and sinkings might be mentioned, as also many more
+    in connection with volcanoes and earthquakes, which are neither
+    slow nor steady, but sudden and violent.</p>
+
+    <p>So it becomes no impossible matter to believe that, in the
+    course of ages past, all those wide reaches of our continents
+    and islands, where sedimentary rocks are to be found, were each
+    in turn, at one time or another, <span class=
+       "pagenum"><a name="page16"
+       id="page16"></a>[pg 16]</span> during long periods, beneath
+       the rolling waters of the ocean....</p>
+    <hr />
+
+    <p>These built-up rocks are not only called "Stratified," and
+    "Sedimentary." They have also the name of <i>Aqueous Rock</i>,
+    from the Latin word <i>aqua, water</i>; because they are
+    believed to have been formed by the action of the water.</p>
+
+    <p>They have yet another and fourth title, which is,
+    <i>Fossiliferous Rocks</i>.</p>
+
+    <p>Fossils are the hardened remains of animals and vegetables
+    found in rocks. They are rarely, if ever, seen in unstratified
+    rocks; but many layers of stratified rocks abound in these
+    remains. Whole skeletons as well as single bones, whole
+    tree-trunks as well as single leaves, are found thus embedded
+    in rock-layers, where in ages past the animal or plant died and
+    found a grave. They exist by thousands in many parts of the
+    world, varying in size from the huge skeleton of the elephant
+    to the tiny shell of the microscopic animalcule.</p>
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/016.png"><img width="200"
+             src="images/016.png"
+             alt="FOSSIL OF CARBONIFEROUS FERN." /></a><br />
+        FOSSIL OF CARBONIFEROUS FERN.
+    </div>
+
+    <p>Fossils differ greatly in kind. Sometimes the entire shell
+    or bone is changed into stone, losing all its animal substance,
+    but retaining its old outline and its natural markings.
+    Sometimes the fossil is merely the hardened impress of the
+    outside of a shell or leaf, which has dented its picture on
+    soft clay, and has itself disappeared, while the soft clay has
+    become rock, <span class="pagenum"><a name="page17"
+       id="page17"></a>[pg 17]</span> and the indented picture
+       remains fixed through after-centuries. Sometimes the fossil
+       is the cast of the inside of a shell; the said shell having
+       been filled with soft mud, which has taken its exact shape
+       and hardened, while the shell itself has vanished. The most
+       complete description of fossil is the first of these three
+       kinds. It is wonderfully shown sometimes in fossil wood,
+       where all the tiny cells and delicate fibres remain
+       distinctly marked as of old, only the whole woody substance
+       has changed into hard stone.</p>
+
+    <div class="figright"
+         style="width:380px;">
+        <a href="images/017-1.png"><img width="380"
+             src="images/017-1.png"
+             alt=
+           "FOOTPRINTS FROM TRIASSIC SANDSTONE OF CONNECTICUT." /></a><br />
+        FOOTPRINTS FROM TRIASSIC SANDSTONE OF CONNECTICUT.
+    </div>
+
+    <p>But although the fossil remains of quadrupeds and other
+    land-animals are found in large quantities, their number is
+    small compared with the enormous number of fossil sea-shells
+    and sea-animals.</p>
+
+    <div class="figleft"
+         style="width:400px;">
+        <a href="images/017-2.png"><img width="400"
+             src="images/017-2.png"
+             alt="FOSSIL FOOTPRINTS." /></a><br />
+        FOSSIL FOOTPRINTS.
+    </div>
+
+    <p>Land-animals can, as a rule, have been so preserved, only
+    when they have been drowned in ponds or rivers, or mired in
+    bogs and swamps, or overtaken by frost, or swept out to
+    sea.</p>
+
+    <p>Sea-animals, on the contrary, have been so preserved on land
+    whenever that land has been under the sea; and this appears to
+    have been the case, at one or another past age, with the
+    greater part of our present <span class="pagenum"><a name=
+    "page18"
+       id="page18"></a>[pg 18]</span> continents. These fossil
+       remains of sea-animals are discovered in all quarters of the
+       world, not only on the seashore but also far inland, not
+       only deep down underground but also high up on the tops of
+       lofty mountains&mdash;a plain proof that over the summits of
+       those mountains the ocean must once have rolled, and this
+       not for a brief space only, but through long periods of
+       time. And not on the mountain-summit only are these fossils
+       known to abound, but sometimes in layer below layer of the
+       mountain, from top to bottom, through thousands of feet of
+       rock.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/018.png"><img width="300"
+             src="images/018.png"
+             alt="FOSSIL SHELLS." /></a><br />
+        FOSSIL SHELLS.
+    </div>
+
+    <p>This may well seem puzzling at first sight. Fossils of
+    sea-creatures on a mountain-top are startling enough; yet
+    hardly so startling as the thought of fossils <i>inside</i>
+    that mountain. How could they have found their way thither?</p>
+
+    <p>The difficulty soon vanishes, if once we clearly understand
+    that all these thousands of feet of rock were built up slowly,
+    layer after layer, when portions of the land lay deep under the
+    sea. Thus <i>each separate layer</i> of mud or sand or other
+    material became in its turn the <i>top layer</i>, and was for
+    the time the floor of the ocean, until further droppings of
+    material out of the waters made a fresh layer, covering up the
+    one below.</p>
+
+    <p>While each layer was thus in succession the top layer of the
+    building, and at the same time the floor <span class=
+    "pagenum"><a name="page19"
+       id="page19"></a>[pg 19]</span> of the ocean, animals lived
+       and died in the ocean, and their remains sank to the bottom,
+       resting upon the sediment floor. Thousands of such dead
+       remains disappeared, crumbling into fine dust and mingling
+       with the waters, but here and there one was caught captive
+       by the half-liquid mud, and was quickly covered and
+       preserved from decay. And still the building went on, and
+       still layer after layer was placed, till many fossils lay
+       deep down beneath the later-formed layers; and when at
+       length, by slow or quick upheaval of the ground, this
+       sea-bottom became a mountain, the little fossils were buried
+       within the body of that mountain. So wondrously the matter
+       appears to have come about.</p>
+    <hr />
+
+    <p>Another difficulty with respect to the stratified rocks has
+    to be thought of. All these layers or deposits of gravel, sand,
+    or earth, on the floor of the ocean, would naturally be
+    horizontal&mdash;that is, would lie flat, one upon another. In
+    places the ocean-floor might slant, or a crevice or valley or
+    ridge might break the smoothness of the deposit. But though the
+    layers might partake of the slant, though the valley might have
+    to be filled, though the ridge might have to be surmounted,
+    still the general tendency of the waves would be to level the
+    dropping deposits into flat layers.</p>
+
+    <p>Then how is it that when we examine the strata of rocks in
+    our neighborhood, wherever that neighborhood may be, we do not
+    find them so arranged? Here, it is true, the lines for a space
+    are nearly horizontal, but there, a little way farther on, they
+    are perpendicular; here they are bent, and there curved; here
+    they are slanting, and there crushed and
+          broken.</p><span class="pagenum"><a name="page20"
+       id="page20"></a>[pg 20]</span>
+
+    <p>This only bears out what has been already said about the
+    Book of Geology. It <i>has</i> been bent and disturbed, crushed
+    and broken.</p>
+
+    <p>Great powers have been at work in this crust of our earth.
+    Continents have been raised, mountains have been upheaved, vast
+    masses of rock have been scattered into fragments. Here or
+    there we may find the layers arranged as they were first laid
+    down; but far more often we discover signs of later
+    disturbance, either slow or sudden, varying from a mere quiet
+    tilting to a violent overturn.</p>
+
+    <div class="figleft"
+         style="width:400px;">
+        <a href="images/020.png"><img width="400"
+             src="images/020.png"
+             alt=
+           "EXAMPLE OF DISTURBANCE OF THE EARTH'S LAYERS." /></a><br />
+        EXAMPLE OF DISTURBANCE OF THE EARTH'S LAYERS.
+    </div>
+
+    <p>So the Book of Geology is a torn and disorganized volume,
+    not easy to read.</p>
+
+    <p>Yet, on the other hand, these very changes which have taken
+    place are a help to the geologist.</p>
+
+    <p>It may seem at first sight as if we should have an easier
+    task, if the strata were all left lying just as they were first
+    formed, in smooth level layers, one above another. But if it
+    were so, we could know very little about the lower layers.</p>
+
+    <p>We might indeed feel sure, as we do now, that the lowest
+    layers were the oldest and the top layers the newest, and that
+    any fossils found in the lower layers must belong to an age
+    farther back than any fossils found in the upper
+    layers.</p><span class="pagenum"><a name="page21"
+       id="page21"></a>[pg 21]</span>
+
+    <p>So much would be clear. And we might dig also and burrow a
+    little way down, through a few different kinds of rock, where
+    they were not too thick. But that would be all. There our
+    powers would cease.</p>
+
+    <p>Now how different. Through the heavings and tiltings of the
+    earth's crust, the lower layers are often pushed quite up to
+    the surface, so that we are able to examine them and their
+    fossils without the least difficulty, and very often without
+    digging underground at all.</p>
+
+    <p>You must not suppose that the real order of the rocks is
+    changed by these movements, for generally speaking it is not.
+    The lower kinds are rarely if ever found placed <i>over</i> the
+    upper kinds; only the ends of them are seen peeping out above
+    ground.</p>
+
+    <p>It is as if you had a pile of copy-books lying flat one upon
+    another, and were to put your finger under the lowest and push
+    it up. All those above would be pushed up also, and perhaps
+    they would slip a little way down, so that you would have a row
+    of <i>edges</i> showing side by side, at very much the same
+    height. The arrangement of the copy-books would not be changed,
+    for the lowest would still be the lowest in actual position;
+    but a general tilting or upheaval would have taken place.</p>
+
+    <p>Just such a tilting or upheaval has taken place again and
+    again with the rocks forming our earth-crust. The edges of the
+    lower rocks often show side by side with those of higher
+    layers.</p>
+
+    <p>But geologists know them apart. They are able to tell
+    confidently whether such and such a rock, peeping out at the
+    earth's surface, belongs really to a lower or
+          <span class="pagenum"><a name="page22"
+       id="page22"></a>[pg 22]</span> a higher kind. For there is a
+       certain sort of order followed in the arrangement of
+       rock-layers all over the earth, and it is well known that
+       some rocks are never found below some other rocks, that
+       certain particular kinds are never placed above certain
+       other kinds. Thus it follows that the fossils found in one
+       description of rock, must be the fossils of animals which
+       lived and died before the animals whose fossil remains are
+       found in another neighboring rock, just because this last
+       rock-layer was built upon the ocean-floor above and
+       therefore later than the other.</p>
+
+    <p>All this is part of the foreign language of
+    geology&mdash;part of the piecing and arranging of the torn
+    volume. Many mistakes are made; many blunders are possible; but
+    the mistakes and blunders are being gradually corrected, and
+    certain rules by which to read and understand are becoming more
+    and more clear.</p>
+
+    <p>It has been already said that unstratified rocks are those
+    which have been at some period, whether lately or very long
+    ago, in a liquid state from intense heat, and which have since
+    cooled, either quickly or slowly, crystallizing as they
+    cooled.</p>
+
+    <p>Unstratified Rocks may be divided into two distinct
+    classes.</p>
+
+    <div class="figleft"
+         style="width:400PX;">
+        <a href="images/022.png"><img width="400"
+             src="images/022.png"
+             alt="SECTION OF A LAVA BOMB." /></a><br />
+        SECTION OF A LAVA BOMB.
+    </div>
+
+    <p>First.&mdash;Volcanic Rocks, such as lava. These have been
+    quickly cooled at the surface of the earth, or not far below
+    it.</p><span class="pagenum"><a name="page23"
+       id="page23"></a>[pg 23]</span>
+
+    <p>Secondly.&mdash;Plutonic Rocks, such as granite. These have
+    been slowly cooled deep down in the earth under heavy
+    pressure.</p>
+
+    <p>There is also a class of rocks, called metamorphic rocks,
+    including some kinds of marble. These are, strictly speaking,
+    crystalline rocks, and yet they are arranged in something like
+    layers. The word "metamorphic" simply means "transformed." They
+    are believed to have been once stratified rocks, perhaps
+    containing often the remains of animals; but intense heat has
+    later transformed them into crystalline rocks, and the animal
+    remains have almost or quite vanished.</p>
+
+    <div class="figright"
+         style="width:400PX;">
+        <a href="images/023.png"><img width="400"
+             src="images/023.png"
+             alt="LAVA-STREAM ON VESUVIUS." /></a><br />
+        LAVA-STREAM ON VESUVIUS.
+    </div>
+
+    <p>Just as the different kinds of Stratified Rocks are often
+    called Aqueous Rocks, or rocks formed by the action of
+    water&mdash;so these different kinds of Unstratified Rocks are
+    often called Igneous Rocks, or rocks formed by the action of
+    fire&mdash;the name being taken from the Latin word for fire.
+    The Metamorphic Rocks are sometimes described as
+    "Aqueo-igneous," since both water and fire helped in the
+    forming of them.</p>
+
+    <p>It was at one time believed, as a matter of certainty, that
+    granite and such rocks belonged to a period much farther back
+    than the periods of the stratified rocks. <span class=
+    "pagenum"><a name="page24"
+       id="page24"></a>[pg 24]</span> That is to say, it was
+       supposed that fire-action had come first and water-action
+       second; that the fire-made rocks were all formed in very
+       early ages, and that only water-made rocks still continued
+       to be formed. So the name of Primary Rocks, or First Rocks,
+       was given to the granites and other such rocks, and the name
+       of Secondary Rocks to all water-built rocks; while those of
+       the third class were called Transition Rocks, because they
+       seemed to be a kind of link or stepping-stone in the change
+       from the First to the Second Rocks.</p>
+
+    <p>The chief reason for the general belief that fire-built
+    rocks were older than water-built ones was, that the former are
+    as a rule found to lie <i>lower</i> than the latter. They form,
+    as it were, the basement of the building, while the top-stories
+    are made of water-built rocks.</p>
+
+    <p>Many still believe that there is much truth in the thought.
+    It is most probable, so far as we are able to judge, that the
+    <i>first-formed</i> crust of rocks all over the earth was of
+    cooled and crystallized material. As these rocks were crumbled
+    and wasted by the ocean, materials would have been supplied for
+    the building-up of rocks, layer upon layer.</p>
+
+    <p>But this is conjecture. We cannot know with any certainty
+    the course of events so far back in the past. And geologists
+    are now able to state with tolerable confidence that, however
+    old many of the granites may be, yet a large amount of the
+    fire-built rocks are no older than the water-built rocks which
+    lie over them.</p>
+
+    <p>So by many geologists the names of Primary, Transition, and
+    Secondary Formations are pretty well given up. It has been
+    proposed to give instead to the <span class=
+       "pagenum"><a name="page25"
+       id="page25"></a>[pg 25]</span> crysallized rocks of all
+       kinds the name of Underlying Rocks (Hypogene Rocks).</p>
+
+    <p>But if they really do lie under, how can they possibly be of
+    the same age? One would scarcely venture to suppose, in looking
+    at a building, that the cellars had not been finished before
+    the upper floors.</p>
+
+    <p>True. In the first instance doubtless the cellars were first
+    made, then the ground-floor, then the upper stories.</p>
+
+    <p>When, however, the house was so built, alterations and
+    improvements might be very widely carried on above and below.
+    While one set of workmen were engaged in remodelling the roof,
+    another set of workmen might be engaged in remodelling the
+    kitchens and first floor, pulling down, propping up, and
+    actually rebuilding parts of the lower walls.</p>
+
+    <p>This is precisely what the two great fellow-workmen, Fire
+    and Water, are ever doing in the crust of our earth. And if it
+    be objected that such alterations too widely undertaken might
+    result in slips, cracks, and slidings, of ceilings and walls in
+    the upper stories, I can only say that such catastrophes
+    <i>have</i> been the result of underground alterations in that
+    great building, the earth's crust....</p>
+
+    <p>We see therefore clearly that, although the earliest
+    fire-made rocks may very likely date farther back than the
+    earliest water-made rocks, yet the making of the two kinds has
+    gone on side by side, one below and the other above ground,
+    through all ages up to the present moment.</p>
+
+    <p>And just as in the present day water continues its
+    <span class="pagenum"><a name="page26"
+       id="page26"></a>[pg 26]</span> busy work above ground of
+       pulling down and building up, so also fire continues its
+       busy work underground of melting rocks which afterwards cool
+       into new forms, and also of shattering and upheaving parts
+       of the earth-crust.</p>
+
+    <p>For there can be no doubt that fiery heat does exist as a
+    mighty power within our earth, though to what extent we are not
+    able to say.</p>
+
+    <p>These two fellow-workers in nature have different modes of
+    working. One we can see on all sides, quietly progressing,
+    demolishing land patiently bit by bit, building up land
+    steadily grain by grain. The other, though more commonly hidden
+    from sight, is fierce and tumultuous in character, and shows
+    his power in occasional terrific outbursts.</p>
+
+    <p>We can scarcely realize what the power is of the imprisoned
+    fiery forces underground, though even we are not without some
+    witness of their existence. From time to time even our firm
+    land has been felt to tremble with a thrill from some far-off
+    shock; and even in our country is seen the marvel of scalding
+    water pouring unceasingly from deep underground....</p>
+
+    <p>Think of the tremendous eruptions of Vesuvius, of Etna, of
+    Hecla, of Mauna Loa. Think of whole towns crushed and buried,
+    with their thousands of living inhabitants. Think of rivers of
+    glowing lava streaming up from regions below ground, and
+    pouring along the surface for a distance of forty, fifty, and
+    even sixty miles, as in Iceland and Hawaii. Think of red-hot
+    cinders flung from a volcano-crater to a height of ten thousand
+    feet. Think of lakes of liquid fire in other craters, five
+    hundred to a thousand feet across, huge <span class=
+    "pagenum"><a name="page27"
+       id="page27"></a>[pg 27]</span> cauldrons of boiling rock.
+       Think of showers of ashes from the furnace below of yet
+       another, borne so high aloft as to be carried seven hundred
+       miles before they sank to earth again. Think of millions of
+       red-hot stones flung out in one eruption of Vesuvius. Think
+       of a mass of rock, one hundred cubic yards in size, hurled
+       to a distance of eight miles or more out of the crater of
+       Cotopaxi.</p>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/027.png"><img width="600"
+             src="images/027.png"
+             alt="HOT WELLS." /></a><br />
+        HOT WELLS.
+    </div>
+
+    <p>Think also of earthquake-shocks felt through twelve hundred
+    miles of country. Think of fierce tremblings and heavings
+    lasting in constant succession through days and weeks of
+    terror. Think of hundreds of miles of land raised several feet
+    in one great upheaval. Think of the earth opening in scores of
+    wide-lipped cracks, to swallow men and beasts. Think of hot
+    mud, boiling water, scalding stream, liquid rock, bursting
+    <span class="pagenum"><a name="page28"
+       id="page28"></a>[pg 28]</span> from such cracks, or pouring
+       from rents in a mountain-side.</p>
+
+    <p>Truly these are signs of a state of things in or below the
+    solid crust on which we live, that may make us doubt the
+    absolute security of "Mother Earth."</p>
+
+    <p>Different explanations have been put forward to explain this
+    seemingly fiery state of things underground.</p>
+
+    <p>Until lately the belief was widely held that our earth was
+    one huge globe of liquid fire, with only a slender cooled crust
+    covering her, a few miles in thickness.</p>
+
+    <p>This view was supported by the fact that heat is found to
+    increase as men descend into the earth. Measurements of such
+    heat-increase have been taken, both in mines and in borings for
+    wells. The usual rate is about one degree more of heat, of our
+    common thermometer, for every fifty or sixty feet of descent.
+    If this were steadily continued, water would boil at a depth of
+    eight thousand feet below the surface; iron would melt at a
+    depth of twenty-eight miles; while at a depth of forty or fifty
+    miles no known substance upon earth could remain solid.</p>
+
+    <p>The force of this proof is, however, weakened by the fact
+    that the rate at which the heat increases differs very much in
+    different places. Also it is now generally supposed that such a
+    tremendous furnace of heat&mdash;a furnace nearly eight
+    thousand miles in diameter&mdash;could not fail to break up and
+    melt so slight a covering shell.</p>
+
+    <p>Many believe, therefore, not that the whole interior of
+    <span class="pagenum"><a name="page29"
+       id="page29"></a>[pg 29]</span> the earth is liquid with
+       heat, but that enormous fire-seas or lakes of melted rock
+       exist here and there, under or in the earth-crust. From
+       these lakes the volcanoes would be fed, and they would be
+       the cause of earthquakes and land-upheavals or
+       land-sinkings. There are strong reasons for supposing that
+       the earth was once a fiery liquid body, and that she has
+       slowly cooled through long ages. Some hold that her centre
+       probably grew solid first from tremendous pressure; that her
+       crust afterwards became gradually cold; and that between the
+       solid crust and the solid inside or "nucleus," a sea of
+       melted rock long existed, the remains of which are still to
+       be found in these tremendous fiery reservoirs.</p>
+
+    <p>The idea accords well with the fact that large numbers of
+    extinct or dead volcanoes are scattered through many parts of
+    the earth. If the above explanation be the right one, doubtless
+    the fire-seas in the crust extended once upon a time beneath
+    such volcanoes, but have since died out or smouldered low in
+    those parts.</p>
+
+    <p>A somewhat curious calculation has been made, to illustrate
+    the different modes of working of these two mighty
+    powers&mdash;Fire and Water.</p>
+
+    <p>The amount of land swept away each year in mud, and borne to
+    the ocean by the River Ganges, was roughly reckoned, and also
+    the amount of land believed to have been upheaved several feet
+    in the great Chilian earthquake.</p>
+
+    <p>It was found that the river, steadily working month by
+    month, would require some four hundred years to carry to the
+    sea the same weight of material, which in <span class=
+    "pagenum"><a name="page30"
+       id="page30"></a>[pg 30]</span> one tremendous effort was
+       upheaved by the fiery underground forces.</p>
+
+    <p>Yet we must not carry this distinction too far. Fire does
+    not always work suddenly, or water slowly; witness the slow
+    rising and sinking of land in parts of the earth, continuing
+    through centuries; and witness also the effects of great floods
+    and storms.</p>
+
+    <p>The crust of the earth is made of rock. But what is rock
+    made of?</p>
+
+    <p>Certain leading divisions of rocks have been already
+    considered:</p>
+
+    <p>The Water-made Rocks;</p>
+
+    <p>The Fire-made Rocks, both Plutonic and Volcanic;</p>
+
+    <p>The Water-and-Fire-made Rocks.</p>
+
+    <p>The first of these&mdash;Water-made Rocks&mdash;may be
+    subdivided into three classes. These are,&mdash;</p>
+
+    <p>I. <i>Flint Rocks</i>; II. <i>Clay Rocks</i>; III. <i>Lime
+    Rocks</i>.</p>
+
+    <p>This is not a book in which it would be wise to go closely
+    into the mineral nature of rocks. Two or three leading thoughts
+    may, however, be given.</p>
+
+    <p>Does it not seem strange that the hard and solid rocks
+    should be in great measure formed of the same substances which
+    form the thin invisible air floating around us?</p>
+
+    <p>Yet so it is. There is a certain gas called Oxygen Gas.
+    Without that gas you could not live many minutes. Banish it
+    from the room in which you are sitting, and in a few minutes
+    you will die.</p>
+
+    <p>This gas makes up nearly one-quarter by weight of the
+    atmosphere round the whole earth.</p><span class=
+    "pagenum"><a name="page31"
+       id="page31"></a>[pg 31]</span>
+
+    <p>The same gas plays an important part in the ocean; for more
+    than three-quarters of water is <i>oxygen</i>.</p>
+
+    <p>It plays also an important part in rocks; for about half the
+    material of the entire earth's crust is oxygen.</p>
+
+    <p>Another chief material in rocks is <i>silicon</i>. This
+    makes up one-quarter of the crust, leaving only one-quarter to
+    be accounted for. Silicon mixed with oxygen makes silica or
+    quartz. There are few rocks which have not a large amount of
+    quartz in them. Common flint, sandstones, and the sand of our
+    shores, are made of quartz, and therefore belong to the first
+    class of Silicious or Flint Rocks. Granites and lavas are about
+    one-half quartz. The beautiful stones, amethyst, agate,
+    chalcedony, and jasper, are all different kinds of quartz.</p>
+
+    <p>Another chief material in rocks is a white metal called
+    <i>aluminium</i>. United to oxygen it becomes alumina, the
+    chief substance in clay. Rocks of this kind&mdash;such as
+    clays, and also the lovely blue gem, sapphire&mdash;are called
+    Argillaceous Rocks, from the Latin word for clay, and belong to
+    the second class. Such rocks keep fossils well.</p>
+
+    <p>Another is <i>calcium</i>. United to oxygen and carbonic
+    acid, it makes carbonate of lime, the chief substance in
+    limestone; so all limestones belong to the third class of
+    Calcareous or Lime Rocks.</p>
+
+    <p>Other important materials may be mentioned, such as
+    <i>magnesium, potassium, sodium, iron, carbon, sulphur,
+    hydrogen, chlorine, nitrogen</i>. These, with many more, not so
+    common, make up the remaining quarter of the earth-crust.</p>
+
+    <p>Carbon plays as important a part in animal and vegetable
+    life as silicon in rocks. Carbon is most <span class=
+    "pagenum"><a name="page32"
+       id="page32"></a>[pg 32]</span> commonly seen in three
+       distinct forms&mdash;as charcoal, as black-lead, and as the
+       pure brilliant diamond. Carbon united, in a particular
+       proportion, to oxygen, forms carbonic acid; and carbonic
+       acid united, in a particular proportion, to lime, forms
+       limestone.</p>
+
+    <p><i>Hydrogen</i> united to oxygen forms water. Each of these
+    two gases is invisible alone, but when they meet and mingle
+    they form a liquid.</p>
+
+    <p><i>Nitrogen</i> united to oxygen and to a small quantity of
+    carbonic acid gas forms our atmosphere.</p>
+
+    <p>Rocks of pure flint, pure clay, or pure lime, are rarely or
+    never met with. Most rocks are made up of several different
+    substances melted together.</p>
+    <hr />
+
+    <p>In the fire-built rocks no remains of animals are found,
+    though in water-built rocks they abound. Water-built rocks are
+    sometimes divided into two classes&mdash;those which only
+    contain occasional animal remains, and those which are more or
+    less built up of the skeletons of animals.</p>
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/032.png"><img width="250"
+             src="images/032.png"
+             alt=
+           "AMIBA PRINCEPS, ONE OF THE MANY ORDERS OF THE RHIZOPODA CLASS, MAGNIFIED ONE HUNDRED TIMES." /></a><br />
+
+        <p>AMIBA PRINCEPS, ONE OF THE MANY ORDERS OF THE RHIZOPODA
+        CLASS, MAGNIFIED ONE HUNDRED TIMES.</p>
+    </div>
+
+    <p>There are some exceedingly tiny creatures inhabiting the
+    ocean, called Rhizopods. They live in minute shells, the
+    largest of which may be almost the size of a grain of wheat,
+    but by far the greater number are invisible as shells without a
+    microscope, and merely show as fine dust. The
+          <span class="pagenum"><a name="page33"
+       id="page33"></a>[pg 33]</span> rhizopods are of different
+       shapes, sometimes round, sometimes spiral, sometimes having
+       only one cell, sometimes having several cells. In the latter
+       case a separate animal lives in each cell. The animal is of
+       the very simplest as well as the smallest kind. He has not
+       even a mouth or a stomach but can take in food at any part
+       of his body.</p><br clear="all" />
+
+    <div class="figright"
+         style="width:300px;">
+        <a href="images/033.png"><img width="300"
+             src="images/033.png"
+             alt="RHIZOPODS (MAGNIFIED)." /></a><br />
+        RHIZOPODS (MAGNIFIED).
+    </div>
+
+    <p>These rhizopods live in the oceans in enormous numbers. Tens
+    of millions are ever coming into existence, living out their
+    tiny lives, dying, and sinking to the bottom.</p>
+
+    <p>There upon the ocean-floor gather their remains, a heaped-up
+    multitude of minute skeletons or shells, layer forming over
+    layer.</p>
+
+    <p>It was long suspected that the white chalk cliffs of England
+    were built up in some such manner as this through past ages.
+    And now at length proof has been found, in the shape of mud
+    dredged up from the ocean-bottom&mdash;mud entirely composed of
+    countless multitudes of these little shells, dropping there by
+    myriads, and becoming slowly joined together in one mass.</p>
+
+    <p>Just so, it is believed, were the white chalk cliffs
+    built&mdash;gradually prepared on the ocean-floor, and then
+    slowly or suddenly upheaved, so as to become a part of the dry
+    land.</p>
+
+    <p>Think what the enormous numbers must have been of tiny
+    living creatures, out of whose shells the wide
+          <span class="pagenum"><a name="page34"
+       id="page34"></a>[pg 34]</span> reaches of white chalk cliffs
+       have been made. Chalk cliffs and chalk layers extend from
+       Ireland, through England and France, as far as to the
+       Crimea. In the south of Russia they are said to be six
+       hundred feet thick. Yet one cubic inch of chalk is
+       calculated to hold the remains of more than one million
+       rhizopods. How many countless millions upon millions must
+       have gone to the whole structure! How long must the work of
+       building up have lasted!</p>
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/034-1.png"><img width="250"
+             src="images/034-1.png"
+             alt="THREE POLYPS OF CORAL." /></a><br />
+        THREE POLYPS OF CORAL.
+    </div>
+
+    <p>These little shells do not always drop softly and evenly to
+    the ocean-floor, to become quietly part of a mass of shells.
+    Sometimes, where the ocean is shallow enough for the waves to
+    have power below, or where land currents can reach, they are
+    washed about, and thrown one against another, and ground into
+    fine powder; and the fine powder becomes in time, through
+    different causes, solid rock.</p>
+
+    <div class="figright"
+         style="width:250px;">
+        <a href="images/034-2.png"><img width="250"
+             src="images/034-2.png"
+             alt="CORAL POLYP." /></a><br />
+        CORAL POLYP.
+    </div>
+
+    <p>Limestone is made in another way also. In the warm waters of
+    the South Pacific Ocean there are many islands, large and
+    small, which have <span class="pagenum"><a name="page35"
+       id="page35"></a>[pg 35]</span> been formed in a wonderful
+       manner by tiny living workers. The workers are soft
+       jelly-like creatures, called polyps, who labor together in
+       building up great walls and masses of coral.</p>
+
+    <div class="figcenter"
+         style="width:600px">
+        <a href="images/035-1.png"><img width="600"
+             src="images/035-1.png"
+             alt="CORAL ISLAND." /></a><br />
+        CORAL ISLAND.
+    </div>
+
+    <div class="figright"
+         style="width:400px;">
+        <a href="images/035-2.png"><img width="400"
+             src="images/035-2.png"
+             alt="YOUNG CORAL POLYP ATTACHED TO A ROCK" /></a><br />
+        YOUNG CORAL POLYP ATTACHED TO A ROCK AND EXPANDED.
+    </div>
+
+    <p>They never carry on their work above the surface of the
+    water, for in the air they would die. But the waves break the
+    coral, and heap it up above high-water mark, and carry earth
+    and seeds to drop there till at length a small low-lying island
+    is formed.</p>
+
+    <p>The waves not only heap up broken coral, but they grind the
+    coral into fine powder, and from this powder limestone rock is
+    made, just as it is from the powdered <span class=
+    "pagenum"><a name="page36"
+       id="page36"></a>[pg 36]</span> shells of rhizopods. The
+       material used by the polyps in building the coral is chiefly
+       lime, which they have the power of gathering out of the
+       water, and the fine coral-powder, sinking to the bottom,
+       makes large quantities of hard limestone. Soft chalk is
+       rarely, if ever, found near the coral islands.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/036.png"><img width="300"
+             src="images/036.png"
+             alt=
+           "WHITE CORAL. 2. PORTION OF A BRANCH (MAGNIFIED)." /></a><br />
+        WHITE CORAL. 2. PORTION OF A BRANCH (MAGNIFIED).
+    </div>
+
+    <p>Limestones are formed in the same manner from the grinding
+    up of other sea-shells and fossils, various in kind; the powder
+    becoming gradually united into solid rock.</p>
+
+    <p>There is yet another way in which limestone is made, quite
+    different from all these. Sometimes streams of water have a
+    large quantity of lime in them; and these as they flow will
+    drop layers of lime which harden into rock. Or a lime-laden
+    spring, making its way through the roof of an underground
+    cavern, will leave all kinds of fantastic arrangements of
+    limestone wherever its waters can trickle and drip. Such a
+    cavern is called a "stalactite cave."</p>
+    <hr />
+
+    <p>So there are different kinds of fossil rock-making. There
+    may be rocks made of other materials, with fossil simply buried
+    in them. There may be rocks <span class="pagenum"><a name=
+    "page37"
+       id="page37"></a>[pg 37]</span> made entirely of fossils,
+       which have gathered in masses as they sank to the
+       sea-bottom, and have there become simply and lightly joined
+       together. There may be rocks made of the ground-up powder of
+       fossils, pressed into a solid substance or united by some
+       other substance.</p>
+
+    <p>Rocks are also often formed of whole fossils, or stones, or
+    shells, bound into one by some natural soft sticky cement,
+    which has gathered round them and afterwards grown hard, like
+    the cement which holds together the stones in a wall.</p>
+
+    <p>The tiny rhizopods (meaning root foot) which have so large a
+    share in chalk and limestone making, are among the smallest and
+    simplest known kinds of animal life.</p>
+
+    <p>There are also some very minute forms of vegetable life,
+    which exist in equally vast numbers, called Diatoms. For a long
+    while they were believed to be living animals, like the
+    rhizopods. Scientific men are now, however, pretty well agreed
+    that they really are only vegetables or plants.</p>
+
+    <p>The diatoms have each one a tiny shell or shield, not made
+    of lime like the rhizopod-shells, but of flint. Some think that
+    common flint may be formed of these tiny shells.</p>
+
+    <p>Again, there is a kind of rock called Mountain Meal, which
+    is entirely made up of the remains of diatoms. Examined under
+    the microscope, thousands of minute flint shields of various
+    shapes are seen. This rock, or earth, is very abundant in many
+    places, and is sometimes used as a polishing powder. In Bohemia
+    there is a layer of it no less than fourteen feet thick. Yet so
+    minute are the shells of which it is composed, that one square
+    inch of rock is said to contain about four <span class=
+    "pagenum"><a name="page38"
+       id="page38"></a>[pg 38]</span> thousand millions of them.
+       Each one of these millions is a separate distinct
+       fossil....</p>
+    <hr />
+
+    <div class="figleft"
+         style="width:250px">
+        <a href="images/038.png"><img width="250"
+             src="images/038.png"
+             alt=
+           "SUCCESSION OF BURIED COAL-GROWTHSAND ERECT TREE-STUMPS. SYDNEY, CAPE BRETON." /></a>
+
+        <p>SUCCESSION OF BURIED COAL-GROWTHS AND ERECT TREE-STUMPS.
+        SYDNEY, CAPE BRETON.</p>
+
+        <p><i>a.</i> Sandstone, <i>b.</i> Shales, <i>c.</i>
+        Coal-seams, <i>d.</i> Bed containing Roots and Stumps <i>in
+        situ</i>.</p>
+    </div>
+
+    <p>If you examine carefully a piece of coal, you will find,
+    more or less clearly, markings like those which are seen in a
+    piece of wood. Sometimes they are very distinct indeed. Coal
+    abounds in impressions of leaves, ferns, and stems, and fossil
+    remains of plants and tree-trunks are found in numbers in
+    coal-seams.</p>
+
+    <p>Coal is a vegetable substance. The wide coal-fields of
+    Britain and other lands are the <i>fossil</i> remains of vast
+    forests.</p>
+
+    <p>Long ages ago, as it seems, broad and luxuriant forests
+    flourished over the earth. In many parts generation after
+    generation of trees lived and died and decayed, leaving no
+    trace of their existence, beyond a little layer of black mould,
+    soon to be carried away by wind and water. Coal could only be
+    formed where there were bogs and quagmires.</p>
+
+    <p>But in bogs and <span class="pagenum"><a name="page39"
+       id="page39"></a>[pg 39]</span> quagmires, and in shallow
+       lakes of low-lying lands, there were great gatherings of
+       slowly-decaying vegetable remains, trees, plants, and ferns
+       all mingling together. Then after a while the low lands
+       would sink and the ocean pouring in would cover them with
+       layers of protecting sand or mud; and sometimes the land
+       would rise again, and fresh forests would spring into life,
+       only to be in their turn overwhelmed anew, and covered by
+       fresh sandy or earthy deposits.</p>
+
+    <p>These buried forests lay through the ages following, slowly
+    hardening into the black and shining coal, so useful now to
+    man.</p>
+
+    <p>The coal is found thus in thin or thick seams, with other
+    rock-layers between, telling each its history of centuries long
+    past. In one place no less than sixteen such beds of coal are
+    found, one below another, each divided from the next above and
+    the next underneath by beds of clay or sand or shale. The
+    forests could not have grown in the sea, and the earth-layers
+    could not have been formed on land, therefore many land-risings
+    and sinkings must have taken place. Each bed probably tells the
+    tale of a succession of forests....</p>
+    <hr />
+
+    <p>Before going on to a sketch of the early ages of the Earth's
+    history&mdash;ages stretching back long long before the time of
+    Adam&mdash;it is needful to think yet for a little longer about
+    the manner in which that history is written, and the way in
+    which it has to be read.</p>
+
+    <p>For the record is one difficult to make out, and its style
+    of expression is often dark and mysterious. There is scarcely
+    any other volume in the great Book of Nature, which the student
+    is so likely to misread as this <span class=
+       "pagenum"><a name="page40"
+       id="page40"></a>[pg 40]</span> one. It is very needful,
+       therefore, to hold the conclusions of geologists with a
+       light grasp, guarding each with a "perhaps" or a "may be."
+       Many an imposing edifice has been built, in geology, upon a
+       rickety foundation which has speedily given way.</p>
+
+    <p>In all ages of the world's history up to the present day,
+    rock-making has taken place&mdash;fire-made rocks being
+    fashioned underground, and water-made rocks being fashioned
+    above ground though under water.</p>
+
+    <p>Also in all ages different kinds of rocks have been
+    fashioned side by side&mdash;limestone in one part of the
+    world, sandstone in another, chalk in another, clay in another,
+    and so on. There have, it is true, been ages when one kind
+    seems to have been the <i>chief</i> kind&mdash;an age of
+    limestone, or an age of chalk. But even then there were
+    doubtless more rock-buildings going on, though not to so great
+    an extent. On the other hand, there may have been ages during
+    which no limestone was made, or no chalk, or no clay. As a
+    general rule, however, the various sorts of rock-building have
+    probably gone on together. This was not so well understood by
+    early geologists as it is now.</p>
+
+    <p>The difficulty is often great of disentangling the different
+    strata, and saying which was earlier and which later
+    formed.</p>
+
+    <p>Still, by close and careful study of the rocks which compose
+    the earth's crust, a certain kind of order is found to exist,
+    more or less followed out in all parts of the world.
+    <i>When</i> each layer was formed in England or in America, the
+    geologist cannot possibly say. He can, however, assert, in
+    either place, that a certain mass of rock was formed before a
+    certain other mass <span class="pagenum"><a name="page41"
+       id="page41"></a>[pg 41]</span> in that same place, even
+       though the two may seem to lie side by side; for he knows
+       that they were so placed only by upheaval, and that once
+       upon a time the one lay beneath the other.</p>
+
+    <p>The geologist can go further. He can often declare that a
+    certain mass of rock in America and a certain mass of rock in
+    England, quite different in kind, were probably built up at
+    about the same time. How long ago that time was he would be
+    rash to attempt to say; but that the two belong to the same age
+    he has good reason for supposing.</p>
+
+    <p>We find rocks piled upon rocks in a certain order, so that
+    we may generally be pretty confident that the lower rocks were
+    first made, and the upper rocks the latest built. Further than
+    this, we find in all the said layers of water-built rocks signs
+    of past life.</p>
+
+    <p>As already stated, much of this life was ocean-life, though
+    not all.</p>
+
+    <p>Below the sea, as the rock-layers were being formed, bit by
+    bit, of earth dropping from the ocean to the ocean's floor,
+    sea-creatures lived out their lives and died by thousands, to
+    sink to that same floor. Millions passed away, dissolving and
+    leaving no trace behind; but thousands were
+    preserved&mdash;shells often, animals sometimes.</p>
+
+    <p>Nor was this all. For now and again some part of the
+    sea-bottom was upheaved, slowly or quickly, till it became dry
+    land. On this dry land animals lived again, and thousands of
+    them, too, died, and their bones crumbled into dust. But here
+    and there one was caught in bog or frost, and his remains were
+    preserved till, through lapse of ages, they turned to
+    stone.</p><span class="pagenum"><a name="page42"
+       id="page42"></a>[pg 42]</span>
+
+    <p>Yet again that land would sink, and over it fresh layers
+    were formed by the ocean-waters, with fresh remains of
+    sea-animals buried in with the layers of sand or lime; and once
+    more the sea-bottom would rise, perhaps then to continue as dry
+    land, until the day when man should discover and handle these
+    hidden remains.</p>
+
+    <p>Now note a remarkable fact as to these fossils, scattered
+    far and wide through the layers of stratified rock.</p>
+
+    <p>In the uppermost and latest built rocks the animals found
+    are the same, in great measure, as those which now exist upon
+    the earth.</p>
+
+    <p>Leaving the uppermost rocks, and examining those which lie a
+    little way below, we find a difference. Some are still the
+    same, and others, if not quite the same, are very much like
+    what we have now; but here and there a creature of a different
+    form appears.</p>
+
+    <p>Go deeper still, and the kinds of animals change further.
+    Fewer and fewer resemble those which now range the earth; more
+    and more belong to other species.</p>
+
+    <p>Descend through layer after layer till we come to rocks
+    built in earliest ages and not one fossil shall we find
+    precisely the same as one animal living now.</p>
+
+    <p>So not only are the rocks built in successive order, stratum
+    after stratum belonging to age after age in the past, but
+    fossil-remains also are found in successive order, kind after
+    kind belonging to past age after age.</p>
+
+    <p>Although in the first instance the succession of fossils was
+    understood by means of the succession of <span class=
+    "pagenum"><a name="page43"
+       id="page43"></a>[pg 43]</span> rock-layers, yet in the
+       second place the arrangement of rock-layers is made more
+       clear by the means of these very fossils.</p>
+
+    <p>A geologist, looking at the rocks in America, can say which
+    there were first-formed, which second-formed, which
+    third-formed. Also, looking at the rocks in England, he can say
+    which there were first-formed, second-formed, third-formed. He
+    would, however, find it very difficult, if not impossible, to
+    say which among any of the American rocks was formed at about
+    the same time as any particular one among the English rocks,
+    were it not for the help afforded him by these fossils.</p>
+
+    <p>Just as the regular succession of rock-strata has been
+    gradually learned, so the regular succession of different
+    fossils is becoming more and more understood. It is now known
+    that some kinds of fossils are always found in the oldest
+    rocks, and in them only; that some kinds are always found in
+    the newest rocks, and in them only; that some fossils are
+    rarely or never found lower than certain layers; that some
+    fossils are rarely or never found higher than certain other
+    layers.</p>
+
+    <p>So this fossil arrangement is growing into quite a history
+    of the past. And a geologist, looking at certain rocks, pushed
+    up from underground, in England and in America, can say: "These
+    are very different kinds of rocks, it is true, and it would be
+    impossible to say how long the building up of the one might
+    have taken place before or after the other. But I see that in
+    both these rocks there are exactly the same kinds of
+    fossil-remains, differing from those in the rocks above and
+    below. I conclude therefore that the two rocks belong to about
+    <span class="pagenum"><a name="page44"
+       id="page44"></a>[pg 44]</span> the same great age in the
+       world's past history, when the same animals were living upon
+       the earth."</p>
+
+    <p>Observing and reasoning thus, geologists have drawn up a
+    general plan or order of strata; and the whole of the vast
+    masses of water-built rocks throughout the world have been
+    arranged in a regular succession of classes, rising step by
+    step from earliest ages up to the present time.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/044.png"><img width="500"
+             src="images/044.png"
+             alt="Water built rocks." /></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="page45"
+       id="page45"></a>[pg 45]</span>
+
+    <h2>AMERICA THE OLD WORLD</h2>
+
+    <h4 class="sc">(From Geological Sketches.)</h4>
+
+    <h3><span class="sc">By</span> L. AGASSIZ.</h3>
+    <hr class="short" />
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/045.png"><img width="250"
+             src="images/045.png"
+             alt="Globe of Americas" /></a>
+    </div>
+
+    <p>First-born among the Continents, though so much later in
+    culture and civilization than some of more recent birth,
+    America, so far as her physical history is concerned, has been
+    falsely denominated the <i>New World</i>. Hers was the first
+    dry land lifted out of the waters, hers the first shore washed
+    by the ocean that enveloped all the earth beside; and while
+    Europe was represented only by islands rising here and there
+    above the sea, America already stretched an unbroken line of
+    land from Nova Scotia to the Far West.</p>
+
+    <p>In the present state of our knowledge, our conclusions
+    respecting the beginning of the earth's history, the way in
+    which it took form and shape as a distinct, separate planet,
+    must, of course, be very vague and <span class=
+    "pagenum"><a name="page46"
+       id="page46"></a>[pg 46]</span> hypothetical. Yet the
+       progress of science is so rapidly reconstructing the past
+       that we may hope to solve even this problem; and to one who
+       looks upon man's appearance upon the earth as the crowning
+       work in a succession of creative acts, all of which have had
+       relation to his coming in the end, it will not seem strange
+       that he should at last be allowed to understand a history
+       which was but the introduction to his own existence. It is
+       my belief that not only the future, but the past also, is
+       the inheritance of man, and that we shall yet conquer our
+       lost birthright.</p>
+
+    <p>Even now our knowledge carries us far enough to warrant the
+    assertion that there was a time when our earth was in a state
+    of igneous fusion, when no ocean bathed it and no atmosphere
+    surrounded it, when no wind blew over it and no rain fell upon
+    it, but an intense heat held all its materials in solution. In
+    those days the rocks which are now the very bones and sinews of
+    our mother Earth&mdash;her granites, her porphyries, her
+    basalts, her syenites&mdash;were melted into a liquid mass. As
+    I am writing for the unscientific reader, who may not be
+    familiar with the facts through which these inferences have
+    been reached, I will answer here a question which, were we
+    talking together, he might naturally ask in a somewhat
+    sceptical tone. How do you know that this state of things ever
+    existed, and, supposing that the solid materials of which our
+    earth consists were ever in a liquid condition, what right have
+    you to infer that this condition was caused by the action of
+    heat upon them? I answer, Because it is acting upon them still;
+    because the earth we tread is but a thin crust floating on a
+    liquid sea of molten <span class="pagenum"><a name="page47"
+       id="page47"></a>[pg 47]</span> materials; because the
+       agencies that were at work then are at work now, and the
+       present is the logical sequence of the past. From artesian
+       wells, from mines, from geysers, from hot springs, a mass of
+       facts has been collected, proving incontestably the heated
+       condition of all substances at a certain depth below the
+       earth's surface; and if we need more positive evidence, we
+       have it in the fiery eruptions that even now bear fearful
+       testimony to the molten ocean seething within the globe and
+       forcing its way but from time to time. The modern progress
+       of Geology has led us by successive and perfectly connected
+       steps back to a time when what is now only an occasional and
+       rare phenomenon was the normal condition of our earth; when
+       the internal fires were enclosed by an envelope so thin that
+       it opposed but little resistance to their frequent outbreak,
+       and they constantly forced themselves through this crust,
+       pouring out melted materials that subsequently cooled and
+       consolidated on its surface. So constant were these
+       eruptions, and so slight was the resistance they
+       encountered, that some portions of the earlier rock-deposits
+       are perforated with numerous chimneys, narrow tunnels as it
+       were, bored by the liquid masses that poured <span class=
+       "pagenum"><a name="page48"
+       id="page48"></a>[pg 48]</span> out through them and greatly
+       modified their first condition.</p>
+
+    <div class="figright"
+         style="width:350px;">
+        <a href="images/047.png"><img width="350"
+             src="images/047.png"
+             alt="IDEAL SECTION OF A VOLCANO IN ACTION." /></a><br />
+        IDEAL SECTION OF A VOLCANO IN ACTION.
+    </div>
+
+    <p>The question at once suggests itself, How was even this thin
+    crust formed? what should cause any solid envelope, however
+    slight and filmy when compared to the whole bulk of the globe,
+    to form upon the surface of such a liquid mass? At this point
+    of the investigation the geologist must appeal to the
+    astronomer; for in this vague and nebulous border-land, where
+    the very rocks lose their outlines and flow into each other,
+    not yet specialized into definite forms and
+    substances,&mdash;there the two sciences meet. Astronomy shows
+    us our planet thrown off from the central mass of which it once
+    formed a part, to move henceforth in an independent orbit of
+    its own. That orbit, it tells us, passed through celestial
+    spaces cold enough to chill this heated globe, and of course to
+    consolidate it externally. We know, from the action of similar
+    causes on a smaller scale and on comparatively insignificant
+    objects immediately about us, what must have been the effect of
+    this cooling process upon the heated mass of the globe. All
+    substances when heated occupy more space than they do when
+    cold. Water, which expands when freezing, is the only exception
+    to this rule. The first effect of cooling the surface of our
+    planet must have been to solidify it, and thus to form a film
+    or crust over it. That crust would shrink as the cooling
+    process went on; in consequence of the shrinking, wrinkles and
+    folds would arise upon it, and here and there, where the
+    tension was too great, cracks and fissures would be produced.
+    In proportion as the surface cooled, the masses within would be
+    affected by the change of <span class="pagenum"><a name=
+    "page49"
+       id="page49"></a>[pg 49]</span> temperature outside of them,
+       and would consolidate internally also, the crust gradually
+       thickening by this process.</p>
+
+    <div class="figcenter"
+         style="width:300px;">
+        <a href="images/069.jpg"><img width="300"
+             src="images/069sm.jpg"
+             alt="A VOLCANO." /></a><br />
+        A VOLCANO.
+    </div>
+
+    <p>But there was another element without the globe, equally
+    powerful in building it up. Fire and water wrought together in
+    this work, if not always harmoniously, at least with equal
+    force and persistency. I have said that there was a time when
+    no atmosphere surrounded the earth; but one of the first
+    results of the cooling of its crust must have been the
+    formation of an atmosphere, with all the phenomena connected
+    with it,&mdash;the rising of vapors, their condensation into
+    clouds, the falling of rains, the gathering of waters upon its
+    surface. Water is a very active agent of destruction, but it
+    works over again the materials it pulls down or wears away, and
+    builds them up anew in other forms. As soon as an ocean washed
+    over the consolidated crust of the globe, it would begin to
+    abrade the surfaces upon which it moved, gradually loosening
+    and detaching materials, to deposit them again as sand or mud
+    or pebbles at its bottom in successive layers, one above
+    another. Thus, in analyzing the crust of the globe, we find at
+    once two kinds of rocks, the respective work of fire and water:
+    the first poured out from the furnaces within, and cooling, as
+    one may see any mass of metal cool that is poured out from a
+    smelting-furnace to-day, in solid crystalline masses, without
+    any division into separate layers or leaves; and the latter in
+    successive beds, one over another, the heavier materials below,
+    the lighter above, or sometimes in alternate layers, as special
+    causes may have determined successive deposits of lighter or
+    heavier materials at some given spot.</p><span class=
+    "pagenum"><a name="page50"
+       id="page50"></a>[pg 50]</span>
+
+    <p>There were many well-fought battles between geologists
+    before it was understood that these two elements had been
+    equally active in building up the crust of the earth. The
+    ground was hotly contested by the disciples of the two
+    geological schools, one of which held that the solid envelope
+    of the earth was exclusively due to the influence of fire,
+    while the other insisted that it had been accumulated wholly
+    under the agency of water. This difference of opinion grew up
+    very naturally; for the great leaders of the two schools lived
+    in different localities, and pursued their investigations over
+    regions where the geological phenomena were of an entirely
+    opposite character,&mdash;the one exhibiting the effect of
+    volcanic eruptions, the other that of stratified deposits. It
+    was the old story of the two knights on opposite sides of the
+    shield, one swearing that it was made of gold, the other that
+    it was made of silver; and almost killing each other before
+    they discovered that it was made of both. So prone are men to
+    hug their theories and shut their eyes to any antagonistic
+    facts, that it is related of Werner, the great leader of the
+    Aqueous school, that he was actually on his way to see a
+    geological locality of especial interest, but, being told that
+    it confirmed the views of his opponents, he turned round and
+    went home again, refusing to see what might force him to change
+    his opinions. If the rocks did not confirm his theory, so much
+    the worse for the rocks,&mdash;he would none of them. At last
+    it was found that the two great chemists, fire and water, had
+    worked together in the vast laboratory of the globe, and since
+    then scientific men have decided to work together also; and if
+    they still have a passage <span class="pagenum"><a name=
+    "page51"
+       id="page51"></a>[pg 51]</span> at arms occasionally over
+       some doubtful point, yet the results of their investigations
+       are ever drawing them nearer to each other,&mdash;since men
+       who study truth, when they reach their goal, must always
+       meet at last on common ground.</p>
+
+    <p>The rocks formed under the influence of heat are called, in
+    geological language, the Igneous, or, as some naturalists have
+    named them, the Plutonic rocks, alluding to their fiery origin,
+    while the others have been called Aqueous or Neptunic rocks, in
+    reference to their origin under the agency of water. A simpler
+    term, however, quite as distinctive, and more descriptive of
+    their structure, is that of the stratified and massive or
+    unstratified rocks. We shall see hereafter how the relative
+    position of these two classes of rocks and their action upon
+    each other enable us to determine the chronology of the earth,
+    to compare the age of her mountains, and, if we have no
+    standard by which to estimate the positive duration of her
+    continents, to say at least which was the first-born among
+    them, and how their characteristic features have been
+    successfully worked out. I am aware that many of these
+    inferences, drawn from what is called "the geological record,"
+    must seem to be the work of the imagination. In a certain sense
+    this is true,&mdash;for imagination, chastened by correct
+    observation, is our best guide in the study of Nature. We are
+    too apt to associate the exercise of this faculty with works of
+    fiction, while it is in fact the keenest detective of
+    truth.</p>
+
+    <div class="figleft"
+         style="width:350px;">
+        <a href="images/052.png"><img width="350"
+             src="images/052.png"
+             alt="DIKES." /></a><br />
+        DIKES.
+    </div>
+
+    <p>Besides the stratified and massive rocks, there is still a
+    third set, produced by the contact of these two, and called, in
+    consequence of the changes thus brought <span class=
+    "pagenum"><a name="page52"
+       id="page52"></a>[pg 52]</span> about, the Metamorphic rocks.
+       The effect of heat upon clay is to bake it into slate;
+       limestone under the influence of heat becomes quick-lime,
+       or, if subjected afterwards to the action of water, it is
+       changed to mortar; sand under the same agency is changed to
+       a coarse kind of glass. Suppose, then, that a volcanic
+       eruption takes place in a region of the earth's surface
+       where successive layers of limestone, of clay, and of
+       sandstone, have been previously deposited by the action of
+       water. If such an eruption has force enough to break through
+       these beds, the hot, melted masses will pour out through the
+       rent, flow over its edges, and fill all the lesser cracks
+       and fissures produced by such a disturbance. What will be
+       the effect upon the stratified rocks? Wherever these liquid
+       masses, melted by a heat more intense than can be produced
+       by any artificial means, have flowed over them or cooled in
+       immediate contact with them, the clays will be changed to
+       slate, the limestone will have assumed a character more like
+       marble, while the sandstone will be vitrified. This is
+       exactly what has been found to be the case, wherever the
+       stratified rocks have been penetrated by the melted masses
+       from beneath. They have been themselves partially melted by
+       the contact, and when they have cooled again, their
+       stratification, though still perceptible, has been partly
+       obliterated, and their substance changed. Such effects
+       <span class="pagenum"><a name="page53"
+       id="page53"></a>[pg 53]</span> may often be traced in dikes,
+       which are only the cracks in rocks filled by materials
+       poured into them at some period of eruption when the melted
+       masses within the earth were thrown out and flowed like
+       water into any inequality or depression of the surface
+       around. The walls enclosing such a dike are often found to
+       be completely altered by contact with its burning contents,
+       and to have assumed a character quite different from the
+       rocks of which they make a part; while the mass itself which
+       fills the fissure shows by the character of its
+       crystallization that it has cooled more quickly on the
+       outside, where it meets the walls, than at the centre.</p>
+
+    <p>The first two great classes of rocks, the unstratified and
+    stratified rocks, represent different epochs in the world's
+    physical history: the former mark its revolutions, while the
+    latter chronicle its periods of rest. All mountains and
+    mountain-chains have been upheaved by great convulsions of the
+    globe, which rent asunder the surface of the earth, destroyed
+    the animals and plants living upon it at the time, and were
+    then succeeded by long intervals of repose, when all things
+    returned to their accustomed order, ocean and river deposited
+    fresh beds in uninterrupted succession, the accumulation of
+    materials went on as before, a new set of animals and plants
+    were introduced, and a time of building up and renewing
+    followed the time of destruction. These periods of revolution
+    are naturally more difficult to decipher than the periods of
+    rest; for they have so torn and shattered the beds they
+    uplifted, disturbing them from their natural relations to each
+    other, that it is not easy to reconstruct the parts and give
+    <span class="pagenum"><a name="page54"
+       id="page54"></a>[pg 54]</span> them coherence and
+       completeness again. But within the last half-century this
+       work has been accomplished in many parts of the world with
+       an amazing degree of accuracy, considering the disconnected
+       character of the phenomena to be studied; and I think I
+       shall be able to convince my readers that the modern results
+       of geological investigation are perfectly sound logical
+       inferences from well-established facts. In this, as in so
+       many other things, we are but "children of a larger growth."
+       The world is the geologist's great puzzle-box; he stands
+       before it like the child to whom the separate pieces of his
+       puzzle remain a mystery till he detects their relation and
+       sees where they fit, and then his fragments grow at once
+       into a connected picture beneath his hand....</p>
+
+    <p>When geologists first turned their attention to the physical
+    history of the earth, they saw at once certain great features
+    which they took to be the skeleton and basis of the whole
+    structure. They saw the great masses of granite forming the
+    mountains and mountain-chains, with the stratified rocks
+    resting against their slopes; and they assumed that granite was
+    the first primary agent, and that all stratified rocks must be
+    of a later formation. Although this involved a partial error,
+    as we shall see hereafter when we trace the upheavals of
+    granite even into comparatively modern periods, yet it held an
+    important geological truth also; for, though granite formations
+    are by no means limited to those early periods, they are
+    nevertheless very characteristic of them, and are indeed the
+    foundation-stones on which the physical history of the globe is
+    built.</p>
+
+    <p>Starting from this landmark, the earlier geologists
+    <span class="pagenum"><a name="page55"
+       id="page55"></a>[pg 55]</span> divided the world's history
+       into three periods. As the historian recognizes Ancient
+       History, the Middle Ages, and Modern History as distinct
+       phases in the growth of the human race, so they
+       distinguished between what they called the Primary period,
+       when, as they believed, no life stirred on the surface of
+       the earth; the Secondary or middle period, when animals and
+       plants were introduced, and the land began to assume
+       continental proportions; and the Tertiary period, or
+       comparatively modern geological times, when the physical
+       features of the earth as well as its inhabitants were
+       approaching more nearly to the present condition of things.
+       But as their investigations proceeded, they found that every
+       one of these great ages of the world's history was divided
+       into numerous lesser epochs, each of which had been
+       characterized by a peculiar set of animals and plants, and
+       had been closed by some great physical convulsion,
+       disturbing and displacing the materials accumulated during
+       such a period of rest.</p>
+
+    <p>The further study of these subordinate periods showed that
+    what had been called Primary formations, namely, the volcanic
+    or Plutonic rocks formerly believed to be confined to the first
+    geological ages, belonged to all the periods, successive
+    eruptions having taken place at all times, pouring up through
+    the accumulated deposits, penetrating and injecting their
+    cracks, fissures, and inequalities, as well as throwing out
+    large masses on the surface. Up to our own day there has never
+    been a period when such eruptions have not taken place, though
+    they have been constantly diminishing in frequency and extent.
+    In consequence of this discovery, that rocks of igneous
+    character were by no <span class="pagenum"><a name="page56"
+       id="page56"></a>[pg 56]</span> means exclusively
+       characteristic of the earliest times, they are now
+       classified together upon very different grounds from those
+       on which geologists first united them; though, as the name
+       <i>Primary</i> was long retained, we still find it applied
+       to them, even in geological works of quite recent date. This
+       defect of nomenclature is to be regretted, as likely to
+       mislead the student, because it seems to refer to time;
+       whereas it no longer signifies the age of the rocks, but
+       simply their character. The name Plutonic or Massive rocks
+       is, however, now almost universally substituted for that of
+       Primary.</p>
+
+    <p>A wide field of investigation still remains to be explored
+    by the chemist and the geologist together, in the mineralogical
+    character of the Plutonic rocks, which differs greatly in the
+    different periods. The earlier eruptions seem to have been
+    chiefly granitic, though this must not be understood in too
+    wide a sense, since there are granite formations even as late
+    as the Tertiary period; those of the middle periods were mostly
+    porphyries and basalts; while in the more recent ones, lavas
+    predominate. We have as yet no clew to the laws by which this
+    distribution of volcanic elements in the formation of the earth
+    is regulated; but there is found to be a difference in the
+    crystals of the Plutonic rocks belonging to different ages,
+    which, when fully understood may enable us to determine the age
+    of any Plutonic rock by its mode of crystallization; so that
+    the mineralogist will as readily tell you by its crystals
+    whether a bit of stone of igneous origin belongs to this or
+    that period of the world's history, as the palæontologist will
+    tell you by its fossils whether a piece of rock
+          <span class="pagenum"><a name="page57"
+       id="page57"></a>[pg 57]</span> of aqueous origin belongs to
+       the Silurian or Devonian or Carboniferous deposits.</p>
+
+    <p>Although subsequent investigations have multiplied so
+    extensively not only the number of geological periods, but also
+    the successive creations that have characterized them, yet the
+    first general division into three great eras was nevertheless
+    founded upon a broad and true generalization. In the first
+    stratified rocks in which any organic remains are found, the
+    highest animals are fishes, and the highest plants are
+    cryptogams; in the middle periods reptiles come in, accompanied
+    by fern and moss forests; in later times quadrupeds are
+    introduced, with a dicotyledonous vegetation. So closely does
+    the march of animal and vegetable life keep pace with the
+    material progress of the world, that we may well consider these
+    three divisions, included under the first general
+    classification of its physical history, as the three Ages of
+    Nature; the more important epochs which subdivide them may be
+    compared to so many great dynasties, while the lesser periods
+    are the separate reigns contained therein. Of such epochs there
+    are ten, well known to geologists; of the lesser periods about
+    sixty are already distinguished, while many more loom up from
+    the dim regions of the past, just discerned by the eye of
+    science, though their history is not yet unravelled.</p>
+
+    <p>Before proceeding further, I will enumerate the geological
+    epochs in their succession, confining myself, however, to such
+    as are perfectly well established, without alluding to those of
+    which the limits are less definitely determined, and which are
+    still subject to doubts and discussions among geologists. As I
+    do not propose to <span class="pagenum"><a name="page58"
+       id="page58"></a>[pg 58]</span> make here any treatise of
+       Geology, but simply to place before my readers some pictures
+       of the old world, with the animals and plants that have
+       inhabited it at various times, I shall avoid, as far as
+       possible, all debatable ground, and confine myself to those
+       parts of my subject which are best known, and can therefore
+       be more clearly presented.</p>
+
+    <div class="figleft"
+         style="width:250px">
+        <a href="images/058.png"><img width="250"
+             src="images/058.png"
+             alt="FOSSIL SCORPION.--SILURIAN PERIOD." /></a><br />
+        FOSSIL SCORPION.&mdash;SILURIAN PERIOD.
+    </div>
+
+    <p>First, we have the Azoic period, <i>devoid of life</i>, as
+    its name signifies,&mdash;namely, the earliest stratified
+    deposits upon the heated film forming the first solid surface
+    of the earth, in which no trace of living thing has ever been
+    found. Next comes the Silurian period, when the crust of the
+    earth had thickened and cooled sufficiently to render the
+    existence of animals and plants upon it possible, and when the
+    atmospheric conditions necessary to their maintenance were
+    already established. Many of the names given to these periods
+    are by no means significant of their character, but are merely
+    the result of accident: as, for instance, that of Silurian,
+    given by Sir Roderick Murchison to this set of beds, because he
+    first studied them in that part of Wales occupied by the
+    ancient tribe of the Silures. The next period, the Devonian,
+    was for a similar reason <span class="pagenum"><a name="page59"
+       id="page59"></a>[pg 59]</span> named after the country of
+       Devonshire in England, where it was first investigated. Upon
+       this follows the Carboniferous period, with the immense
+       deposits of coal from which it derives its name. Then comes
+       the Permian period, named, again, from local circumstances,
+       the first investigation of its deposits having taken place
+       in the province of Permia in Russia. Next in succession we
+       have the Triassic period, so called from the trio of rocks,
+       the red sandstone, Muschel Kalk (shell-limestone), and
+       Keuper (clay), most frequently combined in its formations;
+       the Jurassic, so amply illustrated in the chain of the Jura,
+       where geologists first found the clew to its history; and
+       the Cretaceous period, to which the chalk cliffs of England
+       and all the extensive chalk deposits belong. Upon these
+       follow the so-called Tertiary formations, divided into three
+       periods, all of which have received most characteristic
+       names in this epoch of the world's history we see the first
+       approach to a condition of things resembling that now
+       prevailing, and Sir Charles Lyell has most fitly named
+       <span class="pagenum"><a name="page60"
+       id="page60"></a>[pg 60]</span> its three divisions, the
+       Eocene, Miocene, and Pliocene. The termination of the three
+       words is made from the Greek word <i>Kainos</i>, recent;
+       while <i>Eos</i> signifies dawn, <i>Meion</i> less, and
+       <i>Pleion</i> more. Thus Eocene indicates the dawn of recent
+       species, Pliocene their increase, while Miocene, the
+       intermediate term, means less recent. Above these deposits
+       comes what has been called in science the present
+       period,&mdash;<i>the modern times</i> of the
+       geologist,&mdash;that period to which man himself belongs,
+       and since the beginning of which, though its duration be
+       counted by hundreds of thousands of years, there has been no
+       alteration in the general configuration of the earth,
+       consequently no important modification of its climatic
+       conditions, and no change in the animals and plants
+       inhabiting it.</p>
+
+    <div class="figcenter"
+         style="width:250px">
+        <a href="images/059-1.png"><img width="250"
+             src="images/059-1.png"
+             alt="CRUSTACEA.--DEVONIAN PERIOD." /></a><br />
+        CRUSTACEA.&mdash;DEVONIAN PERIOD.
+    </div>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/059-2.png"><img width="500"
+             src="images/059-2.png"
+             alt="FISH OF THE DEVONIAN PERIOD." /></a><br />
+        FISH OF THE DEVONIAN PERIOD.
+    </div>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/060-1.png"><img width="500"
+             src="images/060-1.png"
+             alt="FISH OF THE CARBONIFEROUS PERIOD." /></a><br />
+        FISH OF THE CARBONIFEROUS PERIOD.
+    </div>
+
+    <div class="figcenter"
+         style="width:300px;">
+        <a href="images/060-2.png"><img width="300"
+             src="images/060-2.png"
+             alt=
+           "FOSSIL VEGETATION OF CARBONIFEROUS PERIOD." /></a><br />
+        FOSSIL VEGETATION OF CARBONIFEROUS PERIOD.
+    </div>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/060-3.png"><img width="300"
+             src="images/060-3.png"
+             alt="FISH OF THE PERMIAN PERIOD." /></a><br />
+        FISH OF THE PERMIAN PERIOD.
+    </div>
+
+    <p>I have spoken of the first of these periods, the Azoic,
+    <span class="pagenum"><a name="page61"
+       id="page61"></a>[pg 61]</span> as having been absolutely
+       devoid of life, and I believe this statement to be strictly
+       true; but I ought to add that there is a difference of
+       opinion among geologists upon this point, many believing
+       that the first surface of our globe may have been inhabited
+       by living beings, but that all traces of their existence
+       have been obliterated by the eruptions of melted materials,
+       which not only altered the character of those earliest
+       stratified rocks, but destroyed all the organic remains
+       contained in them. It will be my object to show, not only
+       that the absence of the climatic and atmospheric conditions
+       essential to organic life, as we understand it, must have
+       rendered the previous existence of any living beings
+       impossible, but also that the completeness of the Animal
+       Kingdom in those deposits where we first find organic
+       remains, its intelligible and coherent connections with the
+       successive creations of all geological times and with the
+       animals now living, afford the strongest internal evidence
+       that we have indeed found in the lower Silurian formations,
+       immediately following the Azoic, the beginning of life upon
+       earth. When a story seems to us complete <span class=
+       "pagenum"><a name="page62"
+       id="page62"></a>[pg 62]</span> and consistent from the
+       beginning to the end, we shall not seek for a first chapter,
+       even though the copy in which we have read it be so torn and
+       defaced as to suggest the idea that some portion of it may
+       have been lost. The unity of the work, as a whole, is an
+       incontestable proof that we possess it in its original
+       integrity. The validity of this argument will be recognized,
+       perhaps, only by those naturalists to whom the Animal
+       Kingdom has begun to appear as a connected whole. For those
+       who do not see order in Nature it can have no value.</p>
+
+    <table summary="images">
+        <tr>
+            <td>
+                <div class="figleft"
+                     style="width:300px;">
+                    <a href="images/061-1.png"><img width="300"
+                         src="images/061-1.png"
+                         alt=
+                       "FOSSILS OF TRIASSIC VEGETATION." /></a><br />
+                    FOSSILS OF TRIASSIC VEGETATION.
+                </div>
+            </td>
+
+            <td>
+                <div class="figright"
+                     style="width:300px;">
+                    <a href="images/061-2.png"><img width="300"
+                         src="images/061-2.png"
+                         alt=
+                       "BIRD OF THE JURASSIC PERIOD.(The Oldest Bird.)" /></a><br />
+                    BIRD OF THE JURASSIC PERIOD.(The Oldest Bird.)
+                </div>
+            </td>
+        </tr>
+    </table><br clear="all" />
+
+    <div class="figcenter"
+         style="width:300px;">
+        <a href="images/062-1.png"><img width="300"
+             src="images/062-1.png"
+             alt=
+           "SKELETON OF BIRD OF THE CRETACEOUS PERIOD." /></a><br />
+        SKELETON OF BIRD OF THE CRETACEOUS PERIOD.
+    </div><br clear="all" />
+
+    <div class="figleft"
+         style="width:350px;">
+        <a href="images/062-2.png"><img width="350"
+             src="images/062-2.png"
+             alt=
+           "SKELETON OF ANIMAL OF THE EOCENE PERIOD." /></a><br />
+        SKELETON OF ANIMAL OF THE EOCENE PERIOD.
+    </div>
+
+    <p>For a table containing the geological periods in their
+    succession, I would refer to any modern text-book of Geology,
+    or to an article in the <i>Atlantic Monthly</i> for March,
+    1862, upon "Methods of Study in Natural History," where they
+    are given in connection with the order of introduction of
+    animals upon earth.</p>
+
+    <p>Were these sets of rocks found always in the regular
+    sequence in which I have enumerated them, their relative age
+    would be <span class="pagenum"><a name="page63"
+       id="page63"></a>[pg 63]</span> easily determined, for their
+       superposition would tell the whole story: the lowest would,
+       of course, be the oldest, and we might follow without
+       difficulty the ascending series, till we reached the
+       youngest and uppermost deposits. But their succession has
+       been broken up by frequent and violent alterations in the
+       configuration of the globe. Land and water have changed
+       their level,&mdash;islands have been transformed to
+       continents,&mdash;sea-bottoms have become dry land, and dry
+       land has sunk to form sea-bottoms,&mdash;Alps and Himalayas,
+       Pyrenees and Apennines, Alleghanies and Rocky Mountains,
+       have had their stormy birthdays since many of these beds
+       have been piled one above another, and there are but few
+       spots on the earth's surface where any number of them may be
+       found in their original order and natural position. When we
+       remember that Europe, which lies before us on the map as a
+       continent, was once an archipelago of islands,&mdash;that,
+       <span class="pagenum"><a name="page64"
+       id="page64"></a>[pg 64]</span> where the Pyrenees raise
+       their rocky barrier between France and Spain, the waters of
+       the Mediterranean and Atlantic met,&mdash;that, where the
+       British Channel flows, dry land united England and France,
+       and Nature in those days made one country of the lands
+       parted since by enmities deeper than the waters that run
+       between,&mdash;when we remember, in short, all the fearful
+       convulsions that have torn asunder the surface of the earth,
+       as if her rocky record had indeed been written on paper, we
+       shall find a new evidence of the intellectual unity which
+       holds together the whole physical history of the globe in
+       the fact that through all the storms of time the
+       investigator is able to trace one unbroken thread of thought
+       from the beginning to the present hour.</p>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/063-1.png"><img width="400"
+             src="images/063-1.png"
+             alt=
+           "SKELETON OF ANIMAL OF THE MIOCENE PERIOD." /></a><br />
+        SKELETON OF ANIMAL OF THE MIOCENE PERIOD.
+    </div>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/063-2.png"><img width="300"
+             src="images/063-2.png"
+             alt=
+           "SKELETON OF ANIMAL OF THE PLIOCENE PERIOD." /></a><br />
+        SKELETON OF ANIMAL OF THE PLIOCENE PERIOD.
+    </div>
+
+    <p>The tree is known by its fruits,&mdash;and the fruits of
+    chance are incoherence, incompleteness, unsteadiness, the
+    stammering utterance of blind, unreasoning force. A coherence
+    that binds all the geological ages in one chain, a stability of
+    purpose that completes in the beings born to-day an intention
+    expressed in the first creatures that swam in the Silurian
+    ocean or crept upon its shores, a steadfastness of thought,
+    practically recognized by man, if not acknowledged by him,
+    whenever he traces the intelligent connection between the facts
+    of Nature and combines them into what he is pleased to call his
+    system of Geology, or Zoölogy, or Botany,&mdash;these things
+    are not the fruits of chance or of an unreasoning force, but
+    the legitimate results of intellectual power. There is a
+    singular lack of logic, as it seems to me, in the views of the
+    materialistic naturalists. While they consider classification,
+    or, <span class="pagenum"><a name="page65"
+       id="page65"></a>[pg 65]</span> in other words, their
+       expression of the relations between animals or between
+       physical facts of any kind, as the work of their
+       intelligence, they believe the relations themselves to be
+       the work of physical causes. The more direct inference
+       surely is, that, if it requires an intelligent mind to
+       recognize them, it must have required an intelligent mind to
+       establish them. These relations existed before man was
+       created; they have existed ever since the beginning of time;
+       hence, what we call the classification of facts is not the
+       work of his mind in any direct original sense, but the
+       recognition of an intelligent action prior to his own
+       existence.</p>
+
+    <p>There is, perhaps, no part of the world, certainly none
+    familiar to science, where the early geological periods can be
+    studied with so much ease and precision as in the United
+    States. Along their northern borders, between Canada and the
+    United States, there runs the low line of hills known as the
+    Laurentian Hills. Insignificant in height, nowhere rising more
+    than fifteen hundred or two thousand feet above the level of
+    the sea, these are nevertheless the first mountains that broke
+    the uniform level of the earth's surface and lifted themselves
+    above the waters. Their low stature, as compared with that of
+    other more lofty mountain-ranges, is in accordance with an
+    invariable rule, by which the relative age of mountains may be
+    estimated. The oldest mountains are the lowest, while the
+    younger and more recent ones tower above their elders, and are
+    usually more torn and dislocated also. This is easily
+    understood, when we remember that all mountains and
+    mountain-chains are the result of upheavals, and that
+    <span class="pagenum"><a name="page66"
+       id="page66"></a>[pg 66]</span> the violence of the outbreak
+       must have been in proportion to the strength of the
+       resistance. When the crust of the earth was so thin that the
+       heated masses within easily broke through it, they were not
+       thrown to so great a height, and formed comparatively low
+       elevations, such as the Canadian hills or the mountains of
+       Bretagne and Wales. But in later times, when young, vigorous
+       giants, such as the Alps, the Himalayas, or, later still,
+       the Rocky Mountains, forced their way out from their fiery
+       prison-house, the crust of the earth was much thicker, and
+       fearful indeed must have been the convulsions which attended
+       their exit.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/066.png"><img width="500"
+             src="images/066.png"
+             alt="A PHYSICAL MAP OF THE UNITED STATES." /></a><br />
+        A PHYSICAL MAP OF THE UNITED STATES.
+    </div>
+
+    <p>The Laurentian Hills form, then, a granite range, stretching
+    from Eastern Canada to the Upper Mississippi, and immediately
+    along its base are gathered the Azoic deposits, the first
+    stratified beds, in which the absence of life need not surprise
+    us, since they were <span class="pagenum"><a name="page67"
+       id="page67"></a>[pg 67]</span> formed beneath a heated
+       ocean. As well might we expect to find the remains of fish
+       or shells or crabs at the bottom of geysers or of boiling
+       springs, as on those early shores bathed by an ocean of
+       which the heat must have been so intense. Although, from the
+       condition in which we find it, this first granite range has
+       evidently never been disturbed by any violent convulsion
+       since its first upheaval, yet there has been a gradual
+       rising of that part of the continent; for the Azoic beds do
+       not lie horizontally along the base of the Laurentian Hills
+       in the position in which they must originally have been
+       deposited, but are lifted and rest against their slopes.
+       They have been more or less dislocated in this process, and
+       are greatly metamorphized by the intense heat to which they
+       must have been exposed. Indeed, all the oldest stratified
+       rocks have been baked by the prolonged action of heat.</p>
+
+    <p>It may be asked how the materials for those first stratified
+    deposits were provided. In later times, when an abundant and
+    various soil covered the earth, when every river brought down
+    to the ocean, not only its yearly tribute of mud or clay or
+    lime, but the débris of animals and plants that lived and died
+    in its waters or along its banks, when every lake and pond
+    deposited at its bottom in successive layers the lighter or
+    heavier materials floating in its waters and settling gradually
+    beneath them, the process by which stratified materials are
+    collected and gradually harden into rock is more easily
+    understood. But when the solid surface of the earth was only
+    just beginning to form, it would seem that the floating matter
+    in the sea can hardly have been in sufficient quantity to form
+    any extensive <span class="pagenum"><a name="page68"
+       id="page68"></a>[pg 68]</span> deposits. No doubt there was
+       some abrasion even of that first crust; but the more
+       abundant source of the earliest stratification is to be
+       found in the submarine volcanoes that poured their liquid
+       streams into the first ocean. At what rate these materials
+       would be distributed and precipitated in regular strata it
+       is impossible to determine; but that volcanic materials were
+       so deposited in layers is evident from the relative position
+       of the earliest rocks. I have already spoken of the
+       innumerable chimneys perforating the Azoic beds, narrow
+       outlets of Plutonic rock, protruding through the earliest
+       strata. Not only are such funnels filled with the
+       crystalline mass of granite that flowed through them in a
+       liquid state, but it has often poured over their sides,
+       mingling with the stratified beds around. In the present
+       state of our knowledge, we can explain such appearances only
+       by supposing that the heated materials within the earth's
+       crust poured out frequently, meeting little
+       resistance,&mdash;that they then scattered and were
+       precipitated in the ocean around, settling in successive
+       strata at its bottom,&mdash;that through such strata the
+       heated masses within continued to pour again and again,
+       forming for themselves the chimney-like outlets above
+       mentioned.</p>
+
+    <p>Such, then, was the earliest American land,&mdash;a long,
+    narrow island, almost continental in its proportions, since it
+    stretched from the eastern borders of Canada nearly to the
+    point where now the base of the Rocky Mountains meets the plain
+    of the Mississippi Valley. We may still walk along its ridge
+    and know that we tread upon the ancient granite that first
+    divided the waters into a northern and southern ocean; and if
+    our <span class="pagenum"><a name="page69"
+       id="page69"></a>[pg 69]</span> imaginations will carry us so
+       far, we may look down toward its base and fancy how the sea
+       washed against this earliest shore of a lifeless world. This
+       is no romance, but the bald, simple truth; for the fact that
+       this granite band was lifted out of the waters so early in
+       the history of the world, and has not since been submerged,
+       has, of course, prevented any subsequent deposits from
+       forming above it. And this is true of all the northern part
+       of the United States. It has been lifted gradually, the beds
+       deposited in one period being subsequently raised, and
+       forming a shore along which those of the succeeding one
+       collected, so that we have their whole sequence before us.
+       In regions where all the geological deposits (Silurian,
+       Devonian, carboniferous, permian, triassic, etc.) are piled
+       one upon another, and we can get a glimpse of their internal
+       relations only where some rent has laid them open, or where
+       their ragged edges, worn away by the abrading action of
+       external influences, expose to view their successive layers,
+       it must, of course, be more difficult to follow their
+       connection. For this reason the American continent offers
+       facilities to the geologist denied to him in the so-called
+       Old World, where the earlier deposits are comparatively
+       hidden, and the broken character of the land, intersected by
+       mountains in every direction, renders his investigation
+       still more difficult. Of course, when I speak of the
+       geological deposits as so completely unveiled to us here, I
+       do not forget the sheet of drift which covers the continent
+       from north to south, and which we shall discuss hereafter,
+       when I reach that part of my subject. But the drift is only
+       a superficial and recent addition to the soil, resting
+       loosely above <span class="pagenum"><a name="page70"
+       id="page70"></a>[pg 70]</span> the other geological
+       deposits, and arising, as we shall see, from very different
+       causes.</p>
+
+    <p>In this article I have intended to limit myself to a general
+    sketch of the formation of the Laurentian Hills with the Azoic
+    stratified beds resting against them. In the Silurian epoch
+    following the Azoic we have the first beach on which any life
+    stirred; it extended along the base of the Azoic beds, widening
+    by its extensive deposits the narrow strip of land already
+    upheaved. I propose ... to invite my readers to a stroll with
+    me along that beach.</p>
+
+    <p>With what interest do we look upon any relic of early human
+    history! The monument that tells of a civilization whose
+    hieroglyphic records we cannot even decipher, the slightest
+    trace of a nation that vanished and left no sign of its life
+    except the rough tools and utensils buried in the old site of
+    its towns or villages, arouses our imagination and excites our
+    curiosity. Men gaze with awe at the inscription on an ancient
+    Egyptian or Assyrian stone; they hold with reverential touch
+    the yellow parchment-roll whose dim, defaced characters record
+    the meagre learning of a buried nationality; and the
+    announcement, that for centuries the tropical forests of
+    Central America have hidden within their tangled growth the
+    ruined homes and temples of a past race, stirs the civilized
+    world with a strange, deep wonder.</p>
+
+    <p>To me it seems, that to look on the first land that was ever
+    lifted above the waste of waters, to follow the shore where the
+    earliest animals and plants were created when the thought of
+    God first expressed itself in organic forms, to hold in one's
+    hand a bit of stone from an old sea-beach, hardened into rock
+    thousands of <span class="pagenum"><a name="page71"
+       id="page71"></a>[pg 71]</span> centuries ago, and studded
+       with the beings that once crept upon its surface or were
+       stranded there by some retreating wave, is even of deeper
+       interest to men than the relies of their own race, for these
+       things tell more directly of the thoughts and creative acts
+       of God.</p>
+
+    <p>Standing in the neighborhood of Whitehall, near Lake George,
+    one may look along such a seashore, and see it stretching
+    westward and sloping gently southward as far as the eye can
+    reach. It must have had a very gradual slope, and the waters
+    must have been very shallow; for at that time no great
+    mountains had been uplifted, and deep oceans are always the
+    concomitants of lofty heights. We do not, however, judge of
+    this by inference merely; we have an evidence of the
+    shallowness of the sea in those days in the character of the
+    shells found in the Silurian deposits, which shows that they
+    belonged in shoal waters.</p>
+
+    <p>Indeed, the fossil remains of all times tell us almost as
+    much of the physical condition of the world at different epochs
+    as they do of its animal and vegetable population. When
+    Robinson Crusoe first caught sight of the footprint on the
+    sand, he saw in it more than the mere footprint, for it spoke
+    to him of the presence of men on his desert island. We walk on
+    the old geological shores, like Crusoe along his beach, and the
+    footprints we find there tell us, too, more than we actually
+    see in them. The crust of our earth is a great cemetery, where
+    the rocks are tombstones on which the buried dead have written
+    their own epitaphs. They tell us not only who they were and
+    when and where they lived, but much also of the circumstances
+    under which they lived. We ascertain the prevalence of certain
+    physical <span class="pagenum"><a name="page72"
+       id="page72"></a>[pg 72]</span> conditions at special epochs
+       by the presence of animals and plants whose existence and
+       maintenance required such a state of things, more than by
+       any positive knowledge respecting it. Where we find the
+       remains of quadrupeds corresponding to our ruminating
+       animals, we infer not only land, but grassy meadows also,
+       and an extensive vegetation; where we find none but marine
+       animals, we know the ocean must have covered the earth; the
+       remains of large reptiles, representing, though in gigantic
+       size, the half aquatic, half terrestrial reptiles of our own
+       period, indicate to us the existence of spreading marshes
+       still soaked by the retreating waters; while the traces of
+       such animals as live now in sand and shoal waters, or in
+       mud, speak to us of shelving sandy beaches and of mud-flats.
+       The eye of the Trilobite tells us that the sun shone on the
+       old beach where he lived; for there is nothing in nature
+       without a purpose, and when so complicated an organ was made
+       to receive the light, there must have been light to enter
+       it. The immense vegetable deposits in the Carboniferous
+       period announce the introduction of an extensive terrestrial
+       vegetation; and the impressions left by the wood and leaves
+       of the trees show that these first forests must have grown
+       in a damp soil and a moist atmosphere. In short, all the
+       remains of animals and plants hidden in the rocks have
+       something to tell of the climatic conditions and the general
+       circumstances under which they lived, and the study of
+       fossils is to the naturalist a thermometer by which he reads
+       the variations of temperature in past times, a plummet by
+       which he sounds the depths of the ancient oceans,&mdash;a
+       register, in fact, of all the important physical changes the
+       earth has undergone.</p><span class="pagenum"><a name=
+       "page73"
+       id="page73"></a>[pg 73]</span>
+
+    <p>But although the animals of the early geological deposits
+    indicate shallow seas by their similarity to our shoal-water
+    animals, it must not be supposed that they are by any means the
+    same. On the contrary, the old shells, crustacea, corals, etc.,
+    represent types which have existed in all times with the same
+    essential structural elements, but under different specific
+    forms in the several geological periods. And here it may not be
+    amiss to say something of what are called by naturalists
+    <i>representative types</i>.</p>
+
+    <p>The statement that different sets of animals and plants have
+    characterized the successive epochs is often understood as
+    indicating a difference of another kind than that which
+    distinguishes animals now living in different parts of the
+    world. This is a mistake. There are so-called representative
+    types all over the globe, united to each other by structural
+    relations and separated by specific differences of the same
+    kind as those that unite and separate animals of different
+    geological periods. Take, for instance, mud-flats or sandy
+    shores in the same latitudes of Europe and America; we find
+    living on each, animals of the same structural character and of
+    the same general appearance, but with certain specific
+    differences, as of color, size, external appendages, etc. They
+    represent each other on the two continents. The American
+    wolves, foxes, bears, rabbits, are not the same as the
+    European, but those of one continent are as true to their
+    respective types as those of the other; under a somewhat
+    different aspect they represent the same groups of animals. In
+    certain latitudes, or under conditions of nearer proximity,
+    these differences may be less marked. It is well
+          <span class="pagenum"><a name="page74"
+       id="page74"></a>[pg 74]</span> known that there is a great
+       monotony of type, not only among animals and plants, but in
+       the human races also, throughout the Arctic regions; and
+       some animals characteristic of the high North reappear under
+       such identical forms in the neighborhood of the snow-fields
+       in lofty mountains, that to trace the difference between the
+       ptarmigans, rabbits, and other gnawing animals of the Alps,
+       for instance, and those of the Arctics, is among the most
+       difficult problems of modern science.</p>
+
+    <p>And so it is also with the animated world of past ages; in
+    similar deposits of sand, mud, or lime, in adjoining regions of
+    the same geological age, identical remains of animals and
+    plants may be found; while at greater distances, but under
+    similar circumstances, representative species may occur. In
+    very remote regions, however, whether the circumstances be
+    similar or dissimilar, the general aspect of the organic world
+    differs greatly, remoteness in space being thus in some measure
+    an indication of the degree of affinity between different
+    faunæ. In deposits of different geological periods immediately
+    following each other, we sometimes find remains of animals and
+    plants so closely allied to those of earlier or later periods
+    that at first sight the specific differences are hardly
+    discernible. The difficulty of solving these questions, and of
+    appreciating correctly the differences and similarities between
+    such closely allied organisms, explains the antagonistic views
+    of many naturalists respecting the range of existence of
+    animals, during longer or shorter geological periods; and the
+    superficial way in which discussions concerning the transition
+    of species are carried on, is mainly owing to an ignorance of
+    the <span class="pagenum"><a name="page75"
+       id="page75"></a>[pg 75]</span> conditions above alluded to.
+       My own personal observation and experience in these matters
+       have led me to the conviction that every geological period
+       has had its own representatives, and that no single species
+       has been repeated in successive ages.</p>
+
+    <p>The laws regulating the geographical distribution of
+    animals, and their combination into distinct zoölogical
+    provinces called faunæ, with definite limits, are very
+    imperfectly understood as yet; but so closely are all things
+    linked together from the beginning that I am convinced we shall
+    never find the clew to their meaning till we carry on our
+    investigations in the past and the present simultaneously. The
+    same principle according to which animal and vegetable life is
+    distributed over the surface of the earth now, prevailed in the
+    earliest geological periods. The geological deposits of all
+    times have had their characteristic faunæ under various zones,
+    their zoölogical provinces presenting special combinations of
+    animal and vegetable life over certain regions, and their
+    representative types reproducing in different countries, but
+    under similar latitudes, the same groups with specific
+    differences.</p>
+
+    <p>Of course, the nearer we approach the beginning of organic
+    life, the less marked do we find the differences to be, and for
+    a very obvious reason. The inequalities of the earth's surface,
+    her mountain-barriers protecting whole continents from the
+    Arctic winds, her open plains exposing others to the full force
+    of the polar blasts, her snug valleys and her lofty heights,
+    her tablelands and rolling prairies, her river-systems and her
+    dry deserts, her cold ocean-currents pouring down from the high
+    North on some of her shores, while warm <span class=
+    "pagenum"><a name="page76"
+       id="page76"></a>[pg 76]</span> ones from tropical seas carry
+       their softer influence to others,&mdash;in short, all the
+       contrasts in the external configuration of the globe, with
+       the physical conditions attendant upon them, are naturally
+       accompanied by a corresponding variety in animal and
+       vegetable life.</p>
+
+    <p>But in the Silurian age, when there were no elevations
+    higher than the Canadian hills, when water covered the face of
+    the earth, with the exception of a few isolated portions lifted
+    above the almost universal ocean, how monotonous must have been
+    the conditions of life! And what should we expect to find on
+    those first shores? If we are walking on a sea-beach to-day, we
+    do not look for animals that haunt the forests or roam over the
+    open plains, or for those that live in sheltered valleys or in
+    inland regions or on mountain-heights. We look for Shells, for
+    Mussels and Barnacles, for Crabs, for Shrimps, for Marine
+    Worms, for Star-Fishes and Sea-Urchins, and we may find here
+    and there a fish stranded on the sand or tangled in the
+    seaweed.</p>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/076.png"><img width="400"
+             src="images/076.png"
+             alt="Hills." /></a>
+    </div><span class="pagenum"><a name="page77"
+       id="page77"></a>[pg 77]</span>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p>
+
+    <h2>SOME RECORDS OF THE ROCKS</h2>
+
+    <h4 class="sc">(From A First Book in Geology.)</h4>
+
+    <h3><span class="sc">By</span> N.S. SHALER, S.D.<a id=
+    "footnotetag1"
+       name="footnotetag1"></a><a href=
+       "#footnote1"><sup>1</sup></a></h3>
+    <hr class="short" />
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/077.png"><img width="250"
+             src="images/077.png"
+             alt="Figures on Rocks." /></a>
+    </div>
+
+    <p>The geologist cannot find his way back in the record of the
+    great stone book, to the far-off day when life began. The
+    various changes that come over rocks from the action of heat,
+    of water, and of pressure, have slowly modified these ancient
+    beds, so that they no longer preserve the frames of the animals
+    that were buried in them.</p>
+
+    <p>These old rocks, which are so changed that we cannot any
+    longer make sure that any animals lived in them, are called the
+    "archæan," which is Greek for ancient. They were probably mud
+    and sand and limestone when first made, but they have been
+    changed to mica schists, gneiss, granite, marble, and other
+    crystalline rocks. When any rock becomes crystalline, the
+    fossils dissolve and disappear, as coins lose their stamp
+    <span class="pagenum"><a name="page78"
+       id="page78"></a>[pg 78]</span> and form when they are melted
+       in the jeweller's gold-pot.</p>
+
+    <p>These ancient rocks that lie deepest in the earth are very
+    thick, and must have taken a great time in building; great
+    continents must have been worn down by rain and waves in order
+    to supply the waste out of which they were made. It is
+    tolerably certain that they took as much time during their
+    making as has been required for all the other times since they
+    were formed. During the vast ages of this archæan the life of
+    our earth began to be. We first find many certain evidences of
+    life in the rocks which lie on top of the archæan rock, and are
+    known as the Cambriani and Silurian periods. There we have
+    creatures akin to our corals and crabs and worms, and others
+    that are the distant kindred of the cuttle-fishes and of our
+    lamp-shells. There were no backboned animals, that is to say,
+    no land mammals, reptiles, or fishes at this stage of the
+    earth's history. It is not likely that there was any land life
+    except of plants and those forms like the lowest ferns, and
+    probably mosses. Nor is it likely that there were any large
+    continents as at the present time, but rather a host of islands
+    lying where the great lands now are, the budding tops of the
+    continents just appearing above the sea.</p>
+
+    <p>Although the life of this time was far simpler than at the
+    present day, it had about as great variety as we would find on
+    our present sea-floors. There were as many different species
+    living at the same time on a given surface.</p>
+
+    <p>The Cambrian and Silurian time&mdash;the time before the
+    coming of the fishes&mdash;must have endured for
+          <span class="pagenum"><a name="page79"
+       id="page79"></a>[pg 79]</span> many million years without
+       any great change in the world. Hosts of species lived and
+       died; half a dozen times or more the life of the earth was
+       greatly changed. New species came much like those that had
+       gone before, and only a little gain here and there was
+       perceptible at any time. Still, at the end of the Silurian,
+       the life of the world had climbed some steps higher in
+       structure and in intelligence.</p>
+
+    <div class="figright"
+         style="width:250px;">
+        <a href="images/079.png"><img width="250"
+             src="images/079.png"
+             alt="FIG. 1. NORTH AMERICA IN CAMBRIAN TIME." /></a><br />
+        FIG. 1. NORTH AMERICA IN CAMBRIAN TIME.
+    </div>
+
+    <p>The next set of periods is known as the Devonian. It is
+    marked by the rapid extension of the fishes; for, although the
+    fishes began in the uppermost Silurian, they first became
+    abundant in this time. These, the first strong-jawed tyrants of
+    the sea, came all at once, like a rush of the old Norman
+    pirates into the peaceful seas of Great Britain. They made a
+    lively time among the sluggish beings of that olden sea.
+    Creatures that were able to meet feebler enemies were swept
+    away or compelled to undergo great changes, and all the life of
+    the oceans seems to have a spur given to it by these
+    quicker-formed and quicker-willed animals. In this Devonian
+    section of our rocks we have proofs that the lands were
+    extensively covered with forests of low fern trees, and we find
+    the first trace of air-breathing animals in certain insects
+    akin to our dragon-flies. In this stage of the earth's history
+    the fishes grew constantly more plentiful, and the seas had a
+    great <span class="pagenum"><a name="page80"
+       id="page80"></a>[pg 80]</span> abundance of corals and
+       crinoids. Except for the fishes, there were no very great
+       changes in the character of the life from that which existed
+       in the earlier time of the Cambrian and Silurian. The
+       animals are constantly changing, but the general nature of
+       the life remains the same as in the earlier time.</p>
+
+    <div class="figleft"
+         style="width:350px;">
+        <a href="images/080.png"><img width="350"
+             src="images/080.png"
+             alt=
+           "FIG. 2. RANICEPS LYELLI--COAL TIME SALAMANDER." /></a><br />
+        FIG. 2. RANICEPS LYELLI&mdash;COAL TIME SALAMANDER.
+    </div>
+
+    <p>In the Carboniferous or coal-bearing age, we have the second
+    great change in the character of the life on the earth. Of the
+    earlier times, we have preserved only the rocks formed in the
+    seas. But rarely do we find any trace of the land life or even
+    of the life that lived along the shores. In this Carboniferous
+    time, however, we have very extensive sheets of rocks which
+    were formed in swamps in the way shown in the earlier part of
+    this book. They constitute our coal-beds, which, though much
+    worn away by rain and sea, still cover a large part of the land
+    surface. These beds of coal grew in the air, and, although the
+    swamps where they were formed had very little animal life in
+    them, we find some fossils which tell us that the life of the
+    land was making great progress; there are new insects,
+    including beetles, cockroaches, spiders, and scorpions, and,
+    what is far more important, there are some air-breathing,
+    back-boned animals, akin to the salamanders and water-dogs of
+    the present day. These were nearly as large as alligators, and
+    of much the same shape, but they were <span class=
+    "pagenum"><a name="page81"
+       id="page81"></a>[pg 81]</span> probably born from the egg in
+       the shape of tadpoles and lived for a time in the water as
+       our young frogs, toads, and salamanders do. This is the
+       first step upwards from the fishes to land vertebrates; and
+       we may well be interested in it, for it makes one most
+       important advance in creatures through whose lives our own
+       existence became possible. Still, these ancient woods of the
+       coal period must have had little of the life we now
+       associate with the forests; there were still no birds, no
+       serpents, no true lizards, no suck-giving animals, no
+       flowers, and no fruits. These coal-period forests were
+       sombre wastes of shade, with no sound save those of the
+       wind, the thunder, and the volcano, or of the running
+       streams and the waves on the shores.</p>
+
+    <p>In the seas of the Carboniferous time, we notice that the
+    ancient life of the earth is passing away. Many creatures, such
+    as the trilobites, die out, and many other forms such as the
+    crinoids or sea lilies become fewer in kind and of less
+    importance. These marks of decay in the marine life continue
+    into the beds just after the Carboniferous, known as the
+    Permian, which are really the last stages of the coal-bearing
+    period.</p>
+
+    <p>When with the changing time we pass to the beds known as the
+    Triassic, which were made just after the close of the
+    Carboniferous time, we find the earth undergoing swift changes
+    in its life. The moist climate and low lands that caused the
+    swamps to grow so rapidly have ceased to be, and in their place
+    we appear to have warm, dry air, and higher lands.</p>
+
+    <p>On these lands of the Triassic time the air-breathing
+    <span class="pagenum"><a name="page82"
+       id="page82"></a>[pg 82]</span> life made very rapid
+       advances. The plants are seen to undergo considerable
+       changes. The ferns no longer make up all the forests, but
+       trees more like the pines began to abound, and insects
+       became more plentiful and more varied.</p>
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/082.png"><img width="200"
+             src="images/082.png"
+             alt=
+           "CYCAS CIRCINALIS, AKIN TO HIGHEST PLANTS OF COAL TIME." /></a>
+
+        <p>FIG. 3. CYCAS CIRCINALIS, AKIN TO HIGHEST PLANTS OF COAL
+        TIME.</p>
+    </div>
+
+    <p>Hitherto the only land back-boned animal was akin to our
+    salamanders. Now we have true lizards in abundance, many of
+    them of large size. Some of them were probably plant-eaters,
+    but most were flesh-eaters; some seem to have been tenants of
+    the early swamps, and some dwelt in the forests.</p>
+
+    <p>The creatures related to the salamanders have increased in
+    the variety of their forms to a wonderful extent. We know them
+    best by the tracks which they have left on the mud stones
+    formed on the borders of lakes or the edge of the sea. In some
+    places these footprints are found in amazing numbers and
+    perfection. The best place for them is in the Connecticut
+    Valley, near Turner's Falls, Mass. At this point the red
+    sandstone and shale beds, which are composed of thin layers
+    having a total thickness of several hundred feet, are often
+    stamped over by these footprints like the mud of a barnyard.
+    From the little we can determine from these footprints, the
+    creatures seem to have been somewhat related to our frogs, but
+    they generally had tails, and, though provided with four legs,
+    were in the habit of walking on the hind ones alone like the
+    <span class="pagenum"><a name="page83"
+       id="page83"></a>[pg 83]</span> kangaroo. A few of these
+       tracks are shown in the figure on this page.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/083-1.png"><img width="500"
+             src="images/083-1.png"
+             alt=
+           "FIG. 4. FOOT-PRINTS, CONNECTICUT SANDSTONES." /></a><br />
+        FIG. 4. FOOT-PRINTS, CONNECTICUT SANDSTONES.
+    </div>
+
+    <p>These strange creatures were of many different species. Some
+    of them must have been six or seven feet high, for their steps
+    are as much as three feet apart, and seem to imply a creature
+    weighing several hundred pounds. Others were not bigger than
+    robins. Strangely enough, we have never found their bones nor
+    the creatures on which they fed, and but for the formation of a
+    little patch of rocks here and there we should not have had
+    even these footprints to prove to us that such creatures had
+    lived in the Connecticut Valley in this far-off time.</p>
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/083-2.png"><img width="200"
+             src="images/083-2.png"
+             alt="FIG. 5. FOOT-PRINT," /></a>
+
+        <p>FIG. 5. FOOT-PRINT, TURNER'S FALLS.</p>
+    </div>
+
+    <p>But these wonderful forms are less interesting than two or
+    three little fossil jaw-bones that prove to us that in this
+    Triassic time the earth now bore another animal more akin to
+    ourselves, in the shape of a little creature that gave suck to
+    its young. Once more life takes a long upward step in this
+    little opossum-like <span class="pagenum"><a name="page84"
+       id="page84"></a>[pg 84]</span> animal, perhaps the first
+       creature whose young was born alive. These little creatures
+       called Microlestes or Dromatherium, of which only one or two
+       different but related species have been found in England and
+       in North Carolina, appear to have been insect-eaters of
+       about the size and shape of the Australian creature shown in
+       Fig. 7. So far we know it in but few
+       specimens,&mdash;altogether only an ounce or two of
+       bones,&mdash;but they are very precious monuments of the
+       past.</p>
+
+    <div class="figleft"
+         style="width:500px;">
+        <a href="images/084-1.png"><img width="500"
+             src="images/084-1.png"
+             alt=
+           "FIG. 6. DROMATHERIUM SYLVESTRE AND TEETH OF MICROLESTES ANTIQUUS." /></a><br />
+        FIG. 6. DROMATHERIUM SYLVESTRE AND TEETH OF MICROLESTES
+        ANTIQUUS.
+    </div>
+
+    <p>In this Triassic time the climate appears to have been
+    rather dry, for in it we have many extensive deposits of salt
+    formed by the evaporation of closed lakes, of seas, such as are
+    now forming on the bottom of the Dead Sea, and the Great Salt
+    Lake of Utah, and a hundred or more other similar basins of the
+    present day.</p>
+
+    <div class="figright"
+         style="width:300px;">
+        <a href="images/084-2.png"><img width="300"
+             src="images/084-2.png"
+             alt="FIG. 7. MYRMECOBIUS." /></a><br />
+        FIG. 7. MYRMECOBIUS.
+    </div>
+
+    <p>In the sea animals of this time we find many changes.
+    Already some of the giant lizard-like animals, which first took
+    shape on the land, are becoming swimming-animals. They changed
+    their feet to paddles, which, with the help of a flattened
+    tail, force them through the water.</p>
+
+    <p>The fishes on which these great swimming lizards preyed are
+    more like the fishes of our present day than <span class=
+    "pagenum"><a name="page85"
+       id="page85"></a>[pg 85]</span> they were before. The
+       trilobites are gone, and of the crinoids only a remnant is
+       left. Most of the corals of the earlier days have
+       disappeared, but the mollusks have not changed more than
+       they did at several different times in the earliest stages
+       of the earth's history.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/085.png"><img width="500"
+             src="images/085.png"
+             alt="FIG. 8. ICHTHYOSAURUS AND PLESIOSAURUS." /></a><br />
+        FIG. 8. ICHTHYOSAURUS AND PLESIOSAURUS.
+    </div>
+
+    <p>After the Trias comes a long succession of ages in which the
+    life of the world is steadily advancing to higher and higher
+    planes; but for a long time there is no such startling change
+    as that which came in the passage from the coal series of rocks
+    to the Trias. This long set of periods is known to geologists
+    as the age of reptiles. It is well named, for the kindred of
+    the lizards then had the control of the land. There were then
+    none of our large fish to dispute their control, so they shaped
+    themselves to suit all the occupations that could give them a
+    chance for a living. Some remained beasts of prey like our
+    alligators, but grew to larger size; some took to eating the
+    plants, and came to walk on their four legs as our ordinary
+    beasts do, no longer dragging themselves on their bellies as do
+    the lizard and alligator, their lower kindred. Others became
+    flying creatures like our bats, only vastly larger, often
+    <span class="pagenum"><a name="page86"
+       id="page86"></a>[pg 86]</span> with a spread of wing of
+       fifteen or twenty feet. Yet others, even as strangely
+       shaped, dwelt with the sharks in the sea.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/086.png"><img width="500"
+             src="images/086.png"
+             alt="FIG. 9. REPTILES OF JURASSIC PERIOD." /></a><br />
+        FIG. 9. REPTILES OF JURASSIC PERIOD.
+    </div>
+
+    <p>In this time of the earth's history we have the first
+    bird-like forms. They were feathered creatures, with bills
+    carrying true teeth, and with strong wings; but they were
+    reptiles in many features, having long, pointed tails such as
+    none of our existing birds have. They show us that the birds
+    are the descendants of reptiles, coming off from them as a
+    branch does from the parent tree. The tortoises began in this
+    series of rocks. At first they are marine or swimming forms,
+    the box-turtles coming later. Here too begin many of the higher
+    insects. Creatures like moths and bees appear, and the forests
+    are enlivened with all the important kinds of insects, though
+    the species were very different from those now living.</p>
+
+    <p>In the age of reptiles the plants have made a considerable
+    advance. Palms are plenty; forms akin to our pines and firs
+    abound, and the old flowerless group of ferns begins to shrink
+    in size, and no longer spreads its feathery foliage over all
+    the land as before. Still <span class="pagenum"><a name=
+    "page87"
+       id="page87"></a>[pg 87]</span> there were none of our common
+       broad-leaved trees; the world had not yet known the oaks,
+       birches, maples, or any of our hard-wood trees that lose
+       their leaves in autumn; nor were the flowering plants, those
+       with gay blossoms, yet on the earth. The woods and fields
+       were doubtless fresh and green, but they wanted the grace of
+       blossoms, plants, and singing-birds. None of the animals
+       could have had the social qualities or the finer instincts
+       that are so common among animals of the present day. There
+       were probably no social animals like our ants and bees, no
+       merry singing creatures; probably no forms that went in
+       herds. Life was a dull round of uncared-for birth, cruel
+       self-seeking, and of death. The animals at best were clumsy,
+       poorly-endowed creatures, with hardly more intelligence than
+       our alligators.</p>
+
+    <p>The little thread of higher life begun in the Microlestes
+    and Dromatherium, the little insect-eating mammals of the
+    forest, is visible all through this time. It held in its warm
+    blood the powers of the time to come, but it was an
+    insignificant thing among the mighty cold-blooded reptiles of
+    these ancient lands. There are several species of them, but
+    they are all small, and have no chance to make headway against
+    the older masters of the earth.</p>
+
+    <p>The Jurassic or first part of the reptilian time shades
+    insensibly into the second part, called the Cretaceous, which
+    immediately follows it. During this period the lands were
+    undergoing perpetual changes; rather deep seas came to cover
+    much of the land surfaces, and there is some reason to believe
+    that the climate of the earth became much colder than it had
+    been, at least in those <span class="pagenum"><a name="page88"
+       id="page88"></a>[pg 88]</span> regions where the great
+       reptiles had flourished. It may be that it is due to a
+       colder climate that we owe the rapid passing away of this
+       gigantic reptilian life of the previous age. The reptiles,
+       being cold-blooded, cannot stand even a moderate winter
+       cold, save when they are so small that they can crawl deep
+       into crevices in the rocks to sleep the winter away, guarded
+       from the cold by the warmth of the earth. At any rate these
+       gigantic animals rapidly ceased to be, so that by the middle
+       of the Cretaceous period they were almost all gone, except
+       those that inhabited the sea; and at the end of this time
+       they had shrunk to lizards in size. The birds continue to
+       increase and to become more like those of our day; their
+       tails shrink away, their long bills lose their teeth; they
+       are mostly water-birds of large size, and there are none of
+       our songsters yet; still they are for the first time perfect
+       birds, and no longer half-lizard in their nature.</p>
+
+    <p>The greatest change in the plants is found in the coming of
+    the broad-leaved trees belonging to the families of our oaks,
+    maples, etc. Now for the first time our woods take on their
+    aspect of to-day; pines and other cone-bearers mingle with the
+    more varied foliage of nut-bearing or large-seeded trees.
+    Curiously enough, we lose sight of the little mammals of the
+    earlier time. This is probably because there is very little in
+    the way of land animals of this period preserved to us. There
+    are hardly any mines or quarries in the beds of this age to
+    bring these fossils to light. In the most of the other rocks
+    there is more to tempt man to explore them for coal ores or
+    building stones.</p>
+
+    <p>In passing from the Cretaceous to the Tertiary, we
+    <span class="pagenum"><a name="page89"
+       id="page89"></a>[pg 89]</span> enter upon the threshold of
+       our modern world. We leave behind all the great wonders of
+       the old world, the gigantic reptiles, the forests of tree
+       ferns, the seas full of ammonites and belemnites, and come
+       among the no less wonderful but more familiar modern forms.
+       We come at once into lands and seas where the back-boned
+       animals are the ruling beings. The reptiles have shrunk to a
+       few low forms,&mdash;the small lizards, the crocodiles and
+       alligators, the tortoises and turtles, and, as if to mark
+       more clearly the banishment of this group from their old
+       empire, the serpents, which are peculiarly degraded forms of
+       reptiles which have lost the legs they once had, came to be
+       the commonest reptiles of the earth.</p>
+
+    <p>The first mammals that have no pouches now appear. In
+    earlier times, the suck-giving animals all belonged to the
+    group that contains our opossums, kangaroos, etc. These
+    creatures are much lower and feebler than the mammals that have
+    no pouches. Although they have probably been on the earth two
+    or three times as long as the higher mammals, they have never
+    attained any eminent success whatever; they cannot endure cold
+    climates; none of them are fitted for swimming as are the seals
+    and whales, or for flying as the bats, or for burrowing as the
+    moles; they are dull, weak things, which are not able to
+    contend with their stronger, better-organized, higher kindred.
+    They seem not only weak, but unable to fit themselves to many
+    different kinds of existence.</p>
+
+    <p>In the lower part of the Tertiary rocks, we find at once a
+    great variety of large beasts that gave suck to their young. It
+    is likely that these creatures had come <span class=
+    "pagenum"><a name="page90"
+       id="page90"></a>[pg 90]</span> into existence in a somewhat
+       earlier time in other lands, where we have not been able to
+       study the fossils; for to make their wonderful forms slowly,
+       as we believe them to have been made, would require a very
+       long time. It is probable that during the Cretaceous time,
+       in some land where we have not yet had a chance to study the
+       rocks, these creatures grew to their varied forms, and that
+       in the beginning of the Tertiary time, they spread into the
+       regions where we find their bones.</p>
+
+    <p>Beginning with the Tertiary time, we find these lower
+    kinsmen of man, through whom man came to be. The mammals were
+    marked by much greater simplicity and likeness to each other
+    than they now have. There were probably no monkeys, no horses,
+    no bulls, no sheep, no goats, no seals, no whales, and no bats.
+    All these animals had many-fingered feet. There were no cloven
+    feet like those of our bulls, and no solid feet as our horses
+    have. Their brains, which by their size give us a general idea
+    of the intelligence of the creature, are small; hence we
+    conclude that these early mammals were less intelligent than
+    those of our day.</p>
+
+    <p>It would require volumes to trace the history of the growth
+    of these early mammals, and show how they, step by step, came
+    to their present higher state. We will take only one of the
+    simplest of these changes, which happens to be also the one
+    which we know best. This is the change that led to the making
+    of our common horses, which seem to have been brought into life
+    on the continent of North America. The most singular thing
+    about our horses is that the feet have but one large toe or
+    finger, the hoof, the hard covering of which is the nail of
+    that extremity. Now it seems <span class="pagenum"><a name=
+    "page91"
+       id="page91"></a>[pg 91]</span> hard to turn the weak,
+       five-fingered feet of the animals of the lower
+       Tertiary&mdash;feet which seem to be better fitted for
+       tree-climbing than anything else&mdash;into feet such as we
+       find in the horse. Yet the change is brought about by easy
+       stages that lead the successive creatures from the weak and
+       loose-jointed foot of the ancient forms to the solid,
+       single-fingered horse's hoof, which is wonderfully
+       well-fitted for carrying a large beast at a swift speed, and
+       is so strong a weapon of defence that an active donkey can
+       kill a lion with a well-delivered kick.</p>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/091.png"><img width="600"
+             src="images/091.png"
+             alt="FIG. 10. FEET OF TERTIARY MAMMALS." /></a><br />
+        FIG. 10. FEET OF TERTIARY MAMMALS.
+    </div>
+
+    <p>The oldest of these creatures that lead to the horses is
+    called <i>Eohippus</i> or beginning horse. This fellow had on
+    the forefeet four large toes, each with a small hoof and fifth
+    imperfect one, which answered to the thumb. The hind feet had
+    gone further in the change, for they each had but three toes,
+    each with hoofs, the middle-toed hoof larger and longer than
+    the others. A little later toward our day we find another
+    advance in the <i>Orohippus</i>, when the little imperfect
+    thumb has disappeared, and there are only four toes on the
+    forefeet and three on the hind.</p><span class=
+    "pagenum"><a name="page92"
+       id="page92"></a>[pg 92]</span>
+
+    <p>Yet later we have the <i>Mesohippus</i> or half-way horse.
+    There are still three toes on the hind foot, but one more of
+    the fingers of the forefeet has disappeared. This time it is
+    the little finger that goes, leaving only a small bone to show
+    that its going was by a slow shrinking. The creature now has
+    three little hoofs on each of its feet.</p>
+
+    <p>Still nearer our own time comes the <i>Miohippus</i>, which
+    shows the two side hoofs on each foot shrinking up so that they
+    do not touch the ground, but they still bear little hoofs.
+    Lastly, about the time of man's coming on the earth, appears
+    his faithful servant, the horse, in which those little side
+    hoofs have disappeared, leaving only two little "splint" bones
+    to mark the place where these side hoofs belong. Thus, step by
+    step, our horses' feet were built up; while these parts were
+    changing, the other parts of the animals were also slowly
+    altering. They were at first smaller than our
+    horses,&mdash;some of them not as large as an ordinary
+    Newfoundland dog; others as small as foxes.</p>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/092.png"><img width="600"
+             src="images/092.png"
+             alt="FIG. 11. DEVELOPMENT OF HORSES'S FOOT." /></a><br />
+        FIG. 11. DEVELOPMENT OF HORSES'S FOOT.
+    </div>
+
+    <p>As if to remind us of his old shape, our horses now and
+    then, but rarely, have, in place of the little splint bones
+    above the hoof, two smaller hoofs, just like the
+          <span class="pagenum"><a name="page93"
+       id="page93"></a>[pg 93]</span> foot of <i>Miohippus</i>.
+       Sometimes these are about the size of a silver dollar, on
+       the part that receives the shoe when horses are shod.</p>
+
+    <p>In this way, by slow-made changes, the early mammals pass
+    into the higher. Out of one original part are made limbs as
+    different as the feet of the horse, the wing of a bat, the
+    paddle of a whale, and the hand of man. So with all the parts
+    of the body the forms change to meet the different uses to
+    which they are put.</p>
+
+    <p>At the end of this long promise, which was written in the
+    very first animals, comes man himself, in form closely akin to
+    the lower animals, but in mind immeasurably apart from them. We
+    can find every part of man's body in a little different shape
+    in the monkeys, but his mind is of a very different quality.
+    While his lower kindred cannot be made to advance in
+    intelligence any more than man himself can grow a horse's foot
+    or a bat's wing, he is constantly going higher and higher in
+    his mental and moral growth.</p>
+
+    <p>So far we have found but few traces of man that lead us to
+    suppose that he has been for a long geological time on the
+    earth, yet there is good evidence that he has been here for a
+    hundred thousand years or more. It seems pretty clear that he
+    has changed little in his body in all these thousands of
+    generations. The earliest remains show us a large-brained
+    creature, who used tools and probably had already made a
+    servant of fire, which so admirably aids him in his work.</p>
+
+    <p>Besides the development of this wonderful series of animals,
+    that we may call in a certain way our kindred, there have been
+    several other remarkable advances in this Tertiary time, this
+    age of crowning wonders in the <span class=
+       "pagenum"><a name="page94"
+       id="page94"></a>[pg 94]</span> earth's history. The birds
+       have gone forward very rapidly; it is likely that there were
+       no songsters at the first part of this period, but these
+       singing birds have developed very rapidly in later times.
+       Among the insects the most remarkable growth is among the
+       ants, the bees, and their kindred. These creatures have very
+       wonderful habits; they combine together for the making of
+       what we may call states, they care for their young, they
+       wage great battles, they keep slaves, they domesticate other
+       insects, and in many ways their acts resemble the doings of
+       man. Coming at about the same time as man, these
+       intellectual insects help to mark this later stage of the
+       earth as the intellectual period in its history. Now for the
+       first time creatures are on the earth which can form
+       societies and help each other in the difficult work of
+       living.</p>
+
+    <p>Among the mollusks, the most important change is in the
+    creation of the great, strong swimming squids, the most
+    remarkable creatures of the sea. Some of these have arms that
+    can stretch for fifty feet from tip to tip.</p>
+
+    <p>Among the plants, the most important change has been in the
+    growth of flowering plants, which have been constantly becoming
+    more plenty, and the plants which bear fruits have also become
+    more numerous. The broad-leaved trees seem to be constantly
+    gaining on the forests of narrow-leaved cone-bearers, which had
+    in an earlier day replaced the forests of ferns.</p>
+
+    <p>In these Tertiary ages, as in the preceding times of the
+    earth, the lands and seas were much changed in their shape. It
+    seems that in the earlier ages the land had been mostly in the
+    shape of large islands grouped <span class=
+       "pagenum"><a name="page95"
+       id="page95"></a>[pg 95]</span> close together where the
+       continents now are. In this time, these islands grew
+       together to form the united lands of Europe, Asia, Africa,
+       Australia, and the twin American continents; so that, as
+       life rose higher, the earth was better fitted for it. Still
+       there were great troubles that it had to undergo. There were
+       at least two different times during the Tertiary age termed
+       glacial periods, times when the ice covered a large part of
+       the northern continents, compelling life of all sorts to
+       abandon great regions, and to find new places in more
+       southern lands. Many kinds of animals and plants seem to
+       have been destroyed in these journeys; but these times of
+       trial, by removing the weaker and less competent creatures,
+       made room for new forms to rise in their places. All advance
+       in nature makes death necessary, and this must come to races
+       as well as to individuals if the life of the world is to go
+       onward and upward.</p>
+
+    <p>Looking back into the darkened past, of which we yet know
+    but little compared with what we would like to know, we can see
+    the great armies of living beings led onward from victory to
+    victory toward the higher life of our own time. Each age sees
+    some advance, though death overtakes all its creatures. Those
+    that escape their actual enemies or accident, fall a prey to
+    old age: volcanoes, earthquakes, glacial periods, and a host of
+    other violent accidents sweep away the life of wide regions,
+    yet the host moves on under a control that lies beyond the
+    knowledge of science. Man finds himself here as the crowning
+    victory of this long war. For him all this life appears to have
+    striven. In his hands lies the profit of all its toil and pain.
+    Surely <span class="pagenum"><a name="page96"
+       id="page96"></a>[pg 96]</span> this should make us feel that
+       our duty to all these living things, that have shared in the
+       struggle that has given man his elevation, is great, but
+       above all, great is our duty to the powers that have been
+       placed in our bodies and our minds.</p>
+
+    <div class="figcenter"
+         style="width:500px">
+        <a href="images/096.png"><img width="500"
+             src="images/096.png"
+             alt="A GLACIER." /></a><br />
+        A GLACIER.
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="page97"
+       id="page97"></a>[pg 97]</span>
+
+    <h2>THE PITCH LAKE IN THE WEST INDIES</h2>
+
+    <h4 class="sc">(From At Last.)</h4>
+
+    <h3><span class="sc">By</span> C. KINGSLEY.</h3>
+    <hr class="short" />
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/097.png"><img width="250"
+             src="images/097.png"
+             alt="COOLIE AND NEGRO." /></a><br />
+        COOLIE AND NEGRO.
+    </div>
+
+    <p>The Pitch Lake, like most other things, owes its appearance
+    on the surface to no convulsion or vagary at all, but to a most
+    slow, orderly, and respectable process of nature, by which
+    buried vegetable matter, which would have become peat, and
+    finally brown coal, in a temperate climate, becomes, under the
+    hot tropic soil, asphalt and oil, continually oozing up beneath
+    the pressure of the strata above it . . . .</p>
+    <hr />
+
+    <p>As we neared the shore, we perceived that the beach was
+    black with pitch; and the breeze being off the land, the
+    asphalt smell (not unpleasant) came off to welcome us. We rowed
+    in, and saw in front of a little row of wooden houses a tall
+    mulatto, in blue policeman's dress, gesticulating and shouting
+    to us. He was <span class="pagenum"><a name="page98"
+       id="page98"></a>[pg 98]</span> the ward policeman, and I
+       found him (as I did all the colored police) able and
+       courteous, shrewd and trusty. These police are excellent
+       specimens of what can be made of the negro, or half-negro,
+       if he be but first drilled, and then given a responsibility
+       which calls out his self-respect. He was warning our crew
+       not to run aground on one or other of the pitch reefs, which
+       here take the place of rocks. A large one, a hundred yards
+       off on the left, has been almost all dug away, and carried
+       to New York or to Paris to make asphalt-pavement.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/098.png"><img width="300"
+             src="images/098.png"
+             alt="THE POLICE STATION." /></a><br />
+        THE POLICE STATION.
+    </div>
+
+    <p>The boat was run ashore, under his directions, on a spit of
+    sand between the pitch; and when she ceased bumping up and down
+    in the muddy surf, we scrambled out into a world exactly the
+    hue of its inhabitants of every shade, from jet black to
+    copper-brown. The pebbles on the shore were pitch. A tide-pool
+    close by was enclosed in pitch; a four-eyes was swimming about
+    in it, staring up at us; and when we hunted him, tried to
+    escape, not by diving, but by jumping on shore on the pitch,
+    and scrambling off between our legs. While the policeman, after
+    profoundest courtesies, was gone to get a mule-cart to take us
+    up to the lake, and planks <span class="pagenum"><a name=
+    "page99"
+       id="page99"></a>[pg 99]</span> to bridge its water channels,
+       we took a look round at this oddest of corners of the
+       earth.</p>
+
+    <p>In front of us was the unit of civilization,&mdash;the
+    police-station, wooden, on wooden stilts (as all well-built
+    houses are here), to insure a draught of air beneath them. We
+    were, of course, asked to come in and sit down, but preferred
+    looking about, under our umbrellas; for the heat was intense.
+    The soil is half pitch, half brown earth, among which the pitch
+    sweals in and out as tallow sweals from a candle. It is always
+    in slow motion under the heat of the tropic sun; and no wonder
+    if some of the cottages have sunk right and left in such a
+    treacherous foundation. A stone or brick house could not stand
+    here; but wood and palm-thatch are both light and tough enough
+    to be safe, let the ground give way as it will.</p>
+
+    <p>The soil, however, is very rich. The pitch certainly does
+    not injure vegetation, though plants will not grow actually in
+    it. The first plants which caught our eyes were pine-apples,
+    for which La Brea is famous. The heat of the soil, as well as
+    the air, brings them to special perfection. They grow about
+    anywhere, unprotected by hedge or fence; for the negroes here
+    seem honest enough, at least toward each other; and at the
+    corner of the house was a bush worth looking at, for we had
+    heard of it for many a year. It bore prickly, heart-shaped pods
+    an inch long, filled with seeds coated with a red waxy
+    pulp.</p>
+
+    <p>This was a famous plant&mdash;<i>Bixa orellana Roucou</i>;
+    and that pulp was the well-known annotto dye of commerce. In
+    England and Holland it is used merely, I believe, to color
+    cheeses, but in the Spanish Main to <span class=
+    "pagenum"><a name="page100"
+       id="page100"></a>[pg 100]</span> color human beings. The
+       Indian of the Orinoco prefers paint to clothes; and when he
+       has "roucoued" himself from head to foot, considers himself
+       in full dress, whether for war or dancing. Doubtless he
+       knows his own business best from long experience. Indeed, as
+       we stood broiling on the shore, we began somewhat to regret
+       that European manners and customs prevented our adopting the
+       Guaraon and Arrawak fashion.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/100.png"><img width="500"
+             src="images/100.png"
+             alt="THE MULE-CART." /></a><br />
+        THE MULE-CART.
+    </div>
+
+    <p>The mule-cart arrived; the lady of the party was put into it
+    on a chair, and slowly bumped and rattled past the corner of
+    Dundonald Street&mdash;so named after the old sea-hero, who
+    was, in his life-time, full of projects for utilizing this same
+    pitch&mdash;and up in pitch road, with a pitch gutter on each
+    side.</p>
+
+    <p>The pitch in the road has been, most of it, laid down by
+    hand, and is slowly working down the slight incline, leaving
+    pools and ruts full of water, often invisible, because covered
+    with a film of brown pitch-dust, and so letting in the unwary
+    walker over his shoes. The <span class="pagenum"><a name=
+    "page101"
+       id="page101"></a>[pg 101]</span> pitch in the gutter-bank is
+       in its native place, and as it spues slowly out of the soil
+       into the ditch in odd wreaths and lumps, we could watch, in
+       little, the process which has produced the whole
+       deposit&mdash;probably the whole lake itself.</p>
+
+    <p>A bullock-cart, laden with pitch, came jolting down past us,
+    and we observed that the lumps, when the fracture is fresh,
+    have all a drawn out look; that the very air bubbles in them,
+    which are often very numerous, are all drawn out likewise, long
+    and oval, like the air-bubbles in some ductile lavas.</p>
+
+    <p>On our left, as we went on, the bush was low, all of yellow
+    cassia and white Hibiscus, and tangled with lovely
+    convolvulus-like creepers, Ipomoea and Echites, with white,
+    purple or yellow flowers. On the right were negro huts and
+    gardens, fewer and fewer as we went on,&mdash;all rich with
+    fruit trees, especially with oranges, hung with fruit of every
+    hue; and beneath them, of course, the pine-apples of La Brea.
+    Everywhere along the road grew, seemingly wild here, that
+    pretty low tree, Cashew, with rounded yellow-veined leaves and
+    little green flowers, followed by a quaint pink and red-striped
+    pear, from which hangs, at the larger and lower end, a
+    kidney-shaped bean, which bold folk eat when roasted; but woe
+    to those who try it when raw; for the acrid oil blisters the
+    lips, and even while the beans are roasting the fumes of the
+    oil will blister the cook's face if she holds it too near the
+    fire.</p>
+
+    <p>As we went onward up the gentle slope (the rise is one
+    hundred and thirty-eight feet in rather more than a mile), the
+    ground became more and more full of pitch, <span class=
+    "pagenum"><a name="page102"
+       id="page102"></a>[pg 102]</span> and the vegetation poorer
+       and more rushy, till it resembled, on the whole, that of an
+       English fen. An Ipomoea or two, and a scarlet flowered dwarf
+       Heliconia, kept up the tropic type, as does a stiff brittle
+       fern about two feet high. We picked the weeds, which looked
+       like English mint or basil, and found that most of them had
+       three longitudinal nerves in each leaf, and were really
+       Melastomas, though dwarfed into a far meaner habit than that
+       of the noble forms we saw at Chaguanas, and again on the
+       other side of the lake. On the right, too, in a hollow, was
+       a whole wood of Groogroo palms, gray stemmed, gray leaved,
+       and here and there a patch of white or black Roseau rose
+       gracefully eight or ten feet high among the reeds.</p>
+
+    <p>The plateau of pitch now widened out, and the whole ground
+    looked like an asphalt pavement, half overgrown with
+    marsh-loving weeds, whose roots feed in the sloppy water which
+    overlies the pitch. But, as yet, there was no sign of the lake.
+    The incline, though gentle, shuts off the view of what is
+    beyond. This last lip of the lake has surely overflowed, and is
+    overflowing still, though very slowly. Its furrows all curve
+    downward; and it is, in fact, as one of our party said, "a
+    black glacier." The pitch, expanding under the burning sun of
+    day, must needs expand most toward the line of least
+    resistance&mdash;that is, downhill; and when it contracts again
+    under the coolness of night, it contracts, surely, from the
+    same cause, more downhill than uphill; and so each particle
+    never returns to the spot whence it started, but rather drags
+    the particles above it downward toward itself. At least, so it
+    seemed to us. Thus may be explained the common mistake which is
+    noticed <span class="pagenum"><a name="page103"
+       id="page103"></a>[pg 103]</span> by Messrs. Wall and Sawkins
+       in their admirable description of the lake.</p>
+
+    <p>"All previous descriptions refer the bituminous matter
+    scattered over the La Brea district, and especially that
+    between the village and the lake, to streams which have issued
+    at some former epoch from the lake, and extended into the sea.
+    This supposition is totally incorrect, as solidification would
+    probably have ensued before it had proceeded one-tenth of the
+    distance; and such of the asphalt as has undoubtedly escaped
+    from the lake has not advanced more than a few yards, and
+    always presents the curved surfaces already described, and
+    never appears as an extended sheet."</p>
+
+    <p>Agreeing with this statement as a whole, I nevertheless
+    cannot but think it probable that a great deal of the asphalt,
+    whether it be in large masses or in scattered veins, may be
+    moving very slowly down hill, from the lake to the sea, by the
+    process of expansion by day and contraction by night, and may
+    be likened to a caterpillar, or rather caterpillars
+    innumerable, progressing by expanding and contracting their
+    rings, having strength enough to crawl down hill, but not
+    strength enough to back up hill again.</p>
+
+    <p>At last we surmounted the last rise, and before us lay the
+    famous lake&mdash;not at the bottom of a depression, as we
+    expected, but at the top of a rise, whence the ground slopes
+    away from it on two sides, and rises from it very slightly on
+    the two others. The black pool glared and glittered in the sun.
+    A group of islands, some twenty yards wide, were scattered
+    about the middle of it. Beyond it rose a double forest of
+    Moriche fan-palms; and to the right of them high
+          <span class="pagenum"><a name="page104"
+       id="page104"></a>[pg 104]</span> wood with giant Mombins and
+       undergrowth of Cocorite&mdash;a paradise on the other side
+       of the Stygian pool.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/104.png"><img width="500"
+             src="images/104.png"
+             alt="THE PITCH LAKE." /></a><br />
+        THE PITCH LAKE.
+    </div>
+
+    <p>We walked, with some misgivings, on to the asphalt, and
+    found it perfectly hard. In a few steps we were stopped by a
+    channel of clear water, with tiny fish and water-beetles in it;
+    and, looking round, saw that the whole lake was intersected
+    with channels, so unlike anything which can be seen elsewhere
+    that it is not easy to describe them.</p>
+
+    <p>Conceive a crowd of mushrooms, of all shapes, from ten to
+    fifty feet across, close together side by side, their tops
+    being kept at exactly the same level, their rounded rims
+    squeezed tight against each other; then conceive water poured
+    on them so as to fill the parting seams, and in the wet season,
+    during which we visited it, to overflow the tops somewhat. Thus
+    would each mushroom represent, tolerably well, one of
+    <span class="pagenum"><a name="page105"
+       id="page105"></a>[pg 105]</span> the innumerable flat
+       asphalt bosses, which seem to have sprung up each from a
+       separate centre, while the parting seams would be of much
+       the same shape as those in the asphalt, broad and shallow
+       atop, and rolling downward in a smooth curve, till they are
+       at bottom mere cracks from two to ten feet deep. Whether
+       these cracks actually close up below, and the two contiguous
+       masses of pitch become one, cannot be seen. As far as the
+       eye goes down, they are two, though pressed close to each
+       other. Messrs. Wall and Sawkins explain the odd fact clearly
+       and simply. The oil, they say, which the asphalt contains
+       when it rises first, evaporates in the sun, of course most
+       on the outside of the heap, leaving a thorough coat of
+       asphalt, which has, generally, no power to unite with the
+       corresponding coat of the next mass. Meanwhile Mr. Manross,
+       an American gentleman, who has written a very clever and
+       interesting account of the lake, seems to have been so far
+       deceived by the curved and squeezed edges of these masses
+       that he attributes to each of them a revolving motion, and
+       supposes that the material is continually passing from the
+       centre to the edges, when it "rolls under," and rises again
+       in the middle. Certainly the strange stuff looks, at the
+       first glance, as if it were behaving in this way; and
+       certainly, also, his theory would explain the appearance of
+       sticks and logs in the pitch. But Messrs. Wall and Sawkins
+       say that they have observed no such motion: nor did we; and
+       I agree with them, that it is not very obvious to what
+       force, or what influence, it could be attributable. We must,
+       therefore, seek some other way of accounting for the
+       sticks&mdash;which utterly <span class="pagenum"><a name=
+       "page106"
+       id="page106"></a>[pg 106]</span> puzzled us, and which Mr.
+       Manross well describes as "numerous pieces of wood, which,
+       being involved in the pitch, are constantly coming to the
+       surface. They are often several feet in length, and five or
+       six inches in diameter. On reaching the surface they
+       generally assume an upright position, one end being detained
+       in the pitch, while the other is elevated by the lifting of
+       the middle. They may be seen at frequent intervals over the
+       lake, standing up to the height of two or even three feet.
+       They look like stumps of trees protruding through the pitch;
+       but their parvenu character is curiously betrayed by a
+       ragged cap of pitch which invariably covers the top, and
+       hangs down like hounds' ears on either side."</p>
+
+    <p>Whence do they come? Have they been blown on to the lake, or
+    left behind by man? or are they fossil trees, integral parts of
+    the vegetable stratum below which is continually rolling
+    upward? or are they of both kinds? I do not know. Only this is
+    certain, as Messrs. Wall and Sawkins have pointed out, that not
+    only "the purer varieties of asphalt, such as approach or are
+    identical with asphalt glance, have been observed" (though not,
+    I think, in the lake itself) "in isolated masses, where there
+    was little doubt of their proceeding from ligneous substances
+    of larger dimensions, such as roots and pieces of trunks and
+    branches," but, moreover, that "it is also necessary to admit a
+    species of conversion by contact, since pieces of wood included
+    accidentally in the asphalt, for example, by dropping from
+    overhanging vegetation, are often found partially transformed
+    into the material." This is a statement which we verified again
+    and again, as we <span class="pagenum"><a name="page107"
+       id="page107"></a>[pg 107]</span> did the one which follows,
+       namely, that the hollow bubbles which abound on the surface
+       of the pitch "generally contain traces of the lighter
+       portion of vegetation," and "are manifestly derived from
+       leaves, etc., which are blown about the lake by the wind,
+       and are covered with asphalt, and, as they become asphalt
+       themselves, give off gases which form bubbles round
+       them."</p>
+
+    <p>But how is it that those logs stand up out of the asphalt,
+    with asphalt caps and hounds' ears (as Mr. Manross well phrases
+    it) on the tops of them?</p>
+
+    <p>We pushed on across the lake, over the planks which the
+    negroes laid down from island to island. Some, meanwhile,
+    preferred a steeple-chase with water-jumps, after the fashion
+    of the midshipmen on a certain second visit to the lake. How
+    the negroes grinned delight and surprise at the vagaries of
+    English lads&mdash;a species of animal altogether new to them;
+    and how they grinned still more when certain staid and portly
+    dignitaries caught the infection, and proved by more than one
+    good leap that they too had been English
+    school-boys&mdash;alas! long, long ago.</p>
+
+    <p>So, whether by bridging, leaping, or wading, we arrived at
+    the little islands, and found them covered with a thick, low
+    scrub; deep sedge, and among them Pinguins, like huge
+    pine-apples without the apple; gray wild-pines, parasites on
+    Matapalos, which, of course, have established themselves, like
+    robbers and vagrants as they are, everywhere; a true holly,
+    with box-like leaves; and a rare cocoa-plum, very like the
+    holly in habit, which seems to be all but confined to these
+    little patches of red earth, afloat on the pitch. Out of the
+    <span class="pagenum"><a name="page108"
+       id="page108"></a>[pg 108]</span> scrub, when we were there,
+       flew off two or three night-jars, very like our English
+       species, save that they had white in the wings; and on the
+       second visit one of the midshipmen, true to the English
+       boy's bird's-nesting instinct, found one of their eggs,
+       white-spotted, in a grass nest.</p>
+
+    <p>Passing these little islands, which are said (I know not how
+    truly) to change their places and number, we came to the very
+    fountains of Styx, to that part of the lake where the asphalt
+    is still oozing up.</p>
+
+    <p>As the wind set toward us, we soon became aware of an evil
+    smell&mdash;petroleum and sulphureted hydrogen at
+    once&mdash;which gave some of us a headache. The pitch here is
+    yellow and white with sulphur foam; so are the water-channels;
+    and out of both water and pitch innumerable bubbles of gas
+    arise, loathsome to the smell. We became aware that the pitch
+    was soft under our feet. We left the impression of our boots;
+    and if we had stood still awhile, we should soon have been
+    ankle-deep. No doubt there are spots where, if a man stayed
+    long enough, he would be slowly and horribly engulfed. "But,"
+    as Mr. Manross says truly, "in no place is it possible to form
+    those bowl-like depressions round the observer described by
+    former travellers." What we did see is that the fresh pitch
+    oozes out at the lines of least resistance, namely, in the
+    channels between the older and more hardened masses, usually at
+    the upper ends of them, so that one may stand on pitch
+    comparatively hard, and put one's hand into pitch quite liquid,
+    which is flowing softly out, like some ugly fungoid growth,
+    such as may be seen in old wine-cellars, into the water. One
+    such pitch-fungus had grown <span class="pagenum"><a name=
+    "page109"
+       id="page109"></a>[pg 109]</span> several yards in length in
+       the three weeks between our first and second visit; and on
+       another, some of our party performed exactly the same feat
+       as Mr. Manross.</p>
+
+    <p>"In one of the star-shaped pools of water, some five feet
+    deep, a column of pitch had been forced perpendicularly up from
+    the bottom. On reaching the surface of the water it had formed
+    a sort of centre-table, about four feet in diameter, but
+    without touching the sides of the pool. The stem was about a
+    foot in diameter. I leaped out on this table, and found that it
+    not only sustained my weight, but that the elasticity of the
+    stem enabled me to rock it from side to side. Pieces torn from
+    the edges of this table sank readily, showing that it had been
+    raised by pressure, and not by its buoyancy."</p>
+
+    <p>True, though strange; but stranger still did it seem to us
+    when we did at last what the negroes asked us, and dipped our
+    hands into the liquid pitch, to find that it did not soil the
+    fingers. The old proverb that one cannot touch pitch without
+    being defiled happily does not stand true here, or the place
+    would be intolerably loathsome. It can be scraped up, moulded
+    into any shape you will, wound in a string (as was done by one
+    of the midshipmen) round a stick, and carried off; but nothing
+    is left on the hand save clean gray mud and water. It may be
+    kneaded for an hour before the mud be sufficiently driven out
+    of it to make it sticky. This very abundance of earthy matter
+    it is which, while it keeps the pitch from soiling, makes it
+    far less valuable than it would be were it pure.</p>
+
+    <p>It is easy to understand whence this earthy matter (twenty
+    or thirty per cent) comes. Throughout the <span class=
+    "pagenum"><a name="page110"
+       id="page110"></a>[pg 110]</span> neighborhood the ground is
+       full, to the depth of hundreds of feet, of coaly and
+       asphaltic matter. Layers of sandstone or of shale containing
+       this decayed vegetable alternate with layers which contain
+       none; and if, as seems probable, the coaly matter is
+       continually changing into asphalt and oil, and then working
+       its way upward through every crack and pore, to escape from
+       the enormous pressure of the superincumbent soil, it must
+       needs carry up with it innumerable particles of the soils
+       through which it passes.</p>
+
+    <p>In five minutes we had seen, handled, and smelt enough to
+    satisfy us with this very odd and very nasty vagary of tropic
+    nature; and as we did not wish to become faint and ill between
+    the sulphureted hydrogen and the blaze of the sun reflected off
+    the hot black pitch, we hurried on over the water-furrows, and
+    through the sedge-beds to the farther shore&mdash;to find
+    ourselves, in a single step, out of an Inferno into a
+    Paradise.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/110.png"><img width="500"
+             src="images/110.png"
+             alt="Pitch pool." /></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="page111"
+       id="page111"></a>[pg 111]</span>
+
+    <h2>A STALAGMITE CAVE</h2>
+
+    <h4 class="sc">(From the Voyage of the Challenger.)</h4>
+
+    <h3><span class="sc">By</span> SIR C. WYVILLE THOMSON, KT.,
+    LL.D., ETC.</h3>
+    <hr class="short" />
+
+    <div class="figleft"
+         style="width:150px">
+        <a href="images/111.png"><img width="150"
+             src="images/111.png"
+             alt="Painter's Vale cave" /></a>
+    </div>
+
+    <p>I think the Painter's Vale cave is the prettiest of the
+    whole. The opening is not very large. It is an arch over a
+    great mass of débris forming a steep slope into the cave, as if
+    part of the roof of the vault had suddenly fallen in. At the
+    foot of the bank of débris one can barely see in the dim light
+    the deep clear water lying perfectly still and reflecting the
+    roof and margin like a mirror. We clambered down the slope, and
+    as the eye became more accustomed to the obscurity the lake
+    stretched further back. There was a crazy little punt moored to
+    the shore, and after lighting candles Captain Nares rowed the
+    Governor back into the darkness, the candles throwing a dim
+    light for a <span class="pagenum"><a name="page112"
+       id="page112"></a>[pg 112]</span> time&mdash;while the voices
+       became more hollow and distant&mdash;upon the surface of the
+       water and the vault of stalactite, and finally passing back
+       as mere specks into the silence.</p><br clear="all" />
+
+    <div class="figright"
+         style="width:225px;">
+        <a href="images/112.png"><img width="225"
+             src="images/112.png"
+             alt="A GUIDE." /></a><br />
+        A GUIDE.
+    </div>
+
+    <p>After landing the Governor on the opposite side, Captain
+    Nares returned for me, and we rowed round the weird little
+    lake. It was certainly very curious and beautiful; evidently a
+    huge cavity out of which the calcareous sand had been washed or
+    dissolved, and whose walls, still to a certain extent
+    permeable, had been hardened and petrified by the constant
+    percolation of water charged with carbonate of lime. From the
+    roof innumerable stalactites, perfectly white, often several
+    yards long and coming down to the delicacy of knitting-needles,
+    hung in clusters; and wherever there was any continuous crack
+    in the roof or wall, a graceful, soft-looking curtain of white
+    stalactite fell, and often ended, much to our surprise. Deep in
+    the water Stalagmites also rose up in pinnacles and fringes
+    through the water, which was so exquisitely still and clear
+    that it was something difficult to tell where the solid marble
+    tracery ended, and its reflected image began. In this cave,
+    which is a considerable distance from the sea, there is a
+    slight change of level with the tide sufficient
+          <span class="pagenum"><a name="page113"
+       id="page113"></a>[pg 113]</span> to keep the water perfectly
+       pure. The mouth of the cave is overgrown with foliage, and
+       every tree is draped and festooned with the fragrant
+       <i>Jasminum gracile</i>, mingled not unfrequently with the
+       "poison ivy" (<i>Rhus toxicodendron</i>). The Bermudians,
+       especially the dark people, have a most exaggerated horror
+       of this bush. They imagine that if one touch it or rub
+       against it he becomes feverish, and is covered with an
+       eruption. This is no doubt entirely mythical. The plant is
+       very poisonous, but the perfume of the flower is rather
+       agreeable, and we constantly plucked and smelt it without
+       its producing any unpleasant effect. The tide was with us
+       when we regained the Flats Bridge, and the galley shot down
+       the rapid like an arrow, the beds of scarlet sponges and the
+       great lazy trepangs showing perfectly clearly on the bottom
+       at a fathom depth.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/113.png"><img width="300"
+             src="images/113.png"
+             alt=
+           "FIG. 1. CALCAREOUS CONCRETION SIMULATING A FOSSIL PALM-STEM, BOAZ ISLAND, BERMUDAS." /></a>
+
+        <p>FIG. 1. CALCAREOUS CONCRETION SIMULATING A FOSSIL
+        PALM-STEM, BOAZ ISLAND, BERMUDAS.</p>
+    </div>
+
+    <p>Every here and there throughout the islands there are groups
+    of bodies of very peculiar form projecting from the surface of
+    the limestone where it has been weathered. These have usually
+    been regarded as fossil palmetto stumps, the roots of trees
+    which have been overwhelmed with sand and whose organic matter
+    has been entirely removed and replaced by carbonate of lime.
+    Fig. 1 represents one of the most characteristic
+          <span class="pagenum"><a name="page114"
+       id="page114"></a>[pg 114]</span> of these from a group on
+       the side of the road in Boaz Island. It is a cylinder a foot
+       in diameter and six inches or so high; the upper surface
+       forms a shallow depression an inch deep surrounded by a
+       raised border; the bottom of the cup is even, and pitted
+       over with small depressions like the marks of rain-drops on
+       sand; the walls of the cylinder seem to end a few inches
+       below the surface of the limestone in a rounded boss, and
+       all over this there are round markings or little cylindrical
+       projections like the origins of rootlets. The object
+       certainly appears to agree even in every detail with a
+       fossil palm-root, and as the palmetto is abundant on the
+       islands and is constantly liable to be destroyed by and
+       ultimately enveloped in a mass of moving sand, it seemed
+       almost unreasonable to question its being one. Still
+       something about the look of these things made me doubt, with
+       General Nelson, whether they were fossil palms, or indeed
+       whether they were of organic origin at all; and after
+       carefully examining and <span class="pagenum"><a name=
+       "page115"
+       id="page115"></a>[pg 115]</span> pondering over several
+       groups of them, at Boaz Island, on the shore at Mount
+       Langton, and elsewhere, I finally came to the conclusion
+       that they were not fossils, but something totally
+       different.</p>
+
+    <div class="figcenter"
+         style="width:300px;">
+        <a href="images/114-1.png"><img width="300"
+             src="images/114-1.png"
+             alt=
+           "FIG. 2. CALCAREOUS CONCRETION IN AEOLIAN LIMESTONE, BERMUDAS." /></a>
+
+        <p>FIG. 2. CALCAREOUS CONCRETION IN AEOLIAN LIMESTONE,
+        BERMUDAS.</p>
+    </div>
+
+    <div class="figcenter"
+         style="width:350px;">
+        <a href="images/114-2.png"><img width="350"
+             src="images/114-2.png"
+             alt=
+           "FIG. 3. CALCAREOUS CONCRETION IN AEOLIAN LIMESTONE, BERMUDAS." /></a>
+
+        <p>FIG. 3. CALCAREOUS CONCRETION IN AEOLIAN LIMESTONE,
+        BERMUDAS.</p>
+    </div>
+
+    <div class="figcenter"
+         style="width:350px;">
+        <a href="images/115-1.png"><img width="350"
+             src="images/115-1.png"
+             alt="FIG. 4. CALCAREOUS CONCRETION, BERMUDAS." /></a>
+
+        <p>FIG. 4. CALCAREOUS CONCRETION, BERMUDAS.</p>
+    </div>
+
+    <div class="figcenter"
+         style="width:275px;">
+        <a href="images/115-2.png"><img width="275"
+             src="images/115-2.png"
+             alt=
+           "FIG. 5. CALCAREOUS CONCRETION IN AEOLIAN LIMESTONE, BERMUDAS." /></a>
+
+        <p>FIG. 5. CALCAREOUS CONCRETION IN AEOLIAN LIMESTONE,
+        BERMUDAS.</p>
+    </div>
+
+    <p>The form given in Fig. 1 is the most characteristic, and
+    probably by far the most common; but very frequently one of a
+    group of these, one which is evidently essentially the same as
+    the rest and formed in the same way, has an oval or an
+    irregular shape (Figs. 2, 3, and 4). In these we have the same
+    raised border, the same scars on the outside, the same origins
+    of root-like fibres, and the same pitting of the bottom of the
+    shallow cup; but their form precludes the possibility of their
+    being tree-roots. In some cases (Fig. 5), a group of so-called
+    "palm-stems" is inclosed in a space surrounded by a ridge, and
+    on examining it closely this outer ridge is found to show the
+    same leaf-scars and traces of rootlets as the "palm-stems"
+    themselves. In some cases very irregular honey-combed figures
+    are produced which the examination <span class=
+    "pagenum"><a name="page116"
+       id="page116"></a>[pg 116]</span> of a long series of
+       intermediate forms shows to belong to the same category
+       (Fig. 6).</p>
+
+    <div class="figleft"
+         style="width:400px;">
+        <a href="images/116.png"><img width="400"
+             src="images/116.png"
+             alt="FIG. 6. CONCRETIONS IN AEOLIAN ROCKS," /></a>
+
+        <p>FIG. 6. CONCRETIONS IN AEOLIAN ROCKS, BERMUDAS.</p>
+    </div>
+
+    <p>In the caves in the limestone, owing to a thread of water
+    having found its way in a particular direction through the
+    porous stone of the roof, a drop falls age after age on one
+    spot on the cave-floor, accurately directed by the stalactite
+    which it is all the time creating. The water contains a certain
+    proportion of carbonate of lime, which is deposited as
+    stalagmite as the water evaporates, and thus a ring-like crust
+    is produced at a little distance from the spot where the drop
+    falls. When a ring is once formed, it limits the spread of the
+    drop, and determines the position of the wall bounding the
+    little pool made by the drop. The floor of the cave gradually
+    rises by the accumulation of sand and travertine, and with it
+    rise the walls and floor of the cup by the deposit of
+    successive layers of stalagmite produced by the drop
+    percolating into the limestone of the floor which hardens it
+    still further, but in this peculiar symmetrical way. From the
+    floor and sides of the cup the water oozes into the softer
+    limestone around and beneath; but, as in all these limestones,
+    it does not ooze indiscriminately, but follows certain more
+    free paths. These become soon lined and finally blocked with
+    <span class="pagenum"><a name="page117"
+       id="page117"></a>[pg 117]</span> stalagmite, and it is these
+       tubes and threads of stalagmite which afterwards in the
+       pseudo-fossil represent the diverging rootlets.</p>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/139.jpg"><img width="400"
+             src="images/139sm.jpg"
+             alt="A STALAGMITE CAVE." /></a><br />
+        A STALAGMITE CAVE.
+    </div>
+
+    <p>Sometimes when two or more drops fall from stalactites close
+    to one another the cups coalesce (Figs. 2, 3, and 4); sometimes
+    one drop or two is more frequent than the other, and then we
+    have the form shown in Figs. 3 and 4; sometimes many drops
+    irregularly scattered form a large pool with its raised border,
+    and a few drops more frequent and more constant than the rest
+    grow their "palmetto stems" within its limit (Fig. 5); and
+    sometimes a number of drops near one another make a curious
+    regular pattern, with the partitions between the recesses quite
+    straight (Fig. 6).</p>
+
+    <p>I have already referred to the rapid denudation which is
+    going on in these islands, and to the extent to which they have
+    been denuded within comparatively recent times. The floors of
+    caves, from their being cemented into a nearly homogeneous mass
+    by stalagmitic matter, are much harder than the ordinary porous
+    blown limestone; and it seems that in many cases, after the
+    rocks forming the walls and roof have been removed,
+    disintegration has been at all events temporarily arrested by
+    the floor. Where there is a flat surface of rock exposed
+    anywhere on the island, it very generally bears traces of
+    having been at one time the floor of a cave; and as the
+    weather-wearing of the surface goes on, the old concretionary
+    structures are gradually brought out again, the parts specially
+    hardened by a localized slow infiltration of lime resist
+    integration longest and project above the general surface.
+    Often <span class="pagenum"><a name="page118"
+       id="page118"></a>[pg 118]</span> a surface of weathered rock
+       is so studded with these symmetrical concretions, that it is
+       hard to believe that one is not looking at the calcified
+       stumps of a close-growing grove of palms.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/118.png"><img width="500"
+             src="images/118.png"
+             alt="Stlagmite cave." /></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="page119"
+       id="page119"></a>[pg 119]</span>
+
+    <h2>THE BIG TREES OF CALIFORNIA</h2>
+
+    <h4 class="sc">(From Studies Scientific and Social.)</h4>
+
+    <h3><span class="sc">By</span> ALFRED RUSSEL WALLACE.</h3>
+    <hr class="short" />
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/119.png"><img width="200"
+             src="images/119.png"
+             alt="Big trees." /></a>
+    </div>
+
+    <p>In the popular accounts of these trees it is usual to dwell
+    only on the dimensions of the very largest known specimens, and
+    sometimes even to exaggerate these. Even the smaller full-grown
+    trees, however, are of grand dimensions, varying from fourteen
+    to eighteen feet in diameter, at six feet above the ground, and
+    keeping nearly the same thickness for perhaps a hundred feet.
+    In the south Calaveras grove, where there are more than a
+    thousand trees, the exquisite beauty of the trunks is well
+    displayed by the numerous specimens in perfect health and
+    vigor. The bark of these trees, seen at a little distance, is
+    of a bright orange brown tint, delicately mottled with darker
+    shades, and with a curious silky or plush-like gloss, which
+    gives them a richness of color far beyond that of any other
+    conifer. The tree which was cut down soon after the first
+    discovery of the species, the <span class="pagenum"><a name=
+    "page120"
+       id="page120"></a>[pg 120]</span> stump of which is now
+       covered with a pavilion, is twenty-five feet in diameter at
+       six feet above the ground, but this is without the thick
+       bark, which would bring it to twenty-seven feet when alive.
+       A considerable portion of this tree still lies where it
+       fell, and at one hundred and thirty feet from the base I
+       found it to be still twelve and a half feet in diameter (or
+       fourteen feet with the bark), while at the extremity of the
+       last piece remaining, two hundred and fifteen feet from its
+       base, it is six feet in diameter, or at least seven feet
+       with the bark. The height of this tree when it was cut down
+       is not recorded, but as one of the living trees is more than
+       three hundred and sixty feet high, it is probable that this
+       giant was not much short of four hundred
+          feet.</p><br clear="all" />
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/120.png"><img width="300"
+             src="images/120.png"
+             alt="THE 'MOTHER OF THE FOREST.'" /></a><br />
+        THE "MOTHER OF THE FOREST."
+    </div>
+
+    <p>In the accompanying picture the dead tree in the centre is
+    that from which the bark was stripped, which was erected in the
+    Crystal Palace and unfortunately destroyed by fire. It is
+    called the "Mother of the <span class="pagenum"><a name=
+    "page121"
+       id="page121"></a>[pg 121]</span> Forest." The two trees
+       nearer the foreground are healthy, medium-sized trees, about
+       fifteen feet diameter at six feet above the ground.</p>
+
+    <p>The huge decayed trunk called "Father of the Forest," which
+    has fallen perhaps a century or more, exhibits the grandest
+    dimensions of any known tree. By measuring its remains, and
+    allowing for the probable thickness of the bark, it seems to
+    have been about thirty-five feet diameter near the ground, at
+    ninety feet up fifteen feet, and even at a height of two
+    hundred and seventy feet, it was nine feet in diameter. It is
+    within the hollow trunk of this tree that a man on horse-back
+    can ride&mdash;both man and horse being rather small; but the
+    dimensions undoubtedly show that it was considerably larger
+    than the "Pavilion tree," and that it carried its huge
+    dimensions to a greater altitude; and although this does not
+    prove it to have been much taller, yet it was in all
+    probability more than four hundred feet in
+          height.</p><br clear="all" />
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/122.png"><img width="400"
+             src="images/122.png"
+             alt="Tunnel through tree." /></a>
+    </div>
+
+    <p>Very absurd statements are made to visitors as to the
+    antiquity of these trees, three or four thousand years being
+    usually given as their age. This is founded on the fact that
+    while many of the large Sequoias are greatly damaged by fire,
+    the large pines and firs around them are quite uninjured. As
+    many of these pines are assumed to be near a thousand years
+    old, the epoch of the "great fire" is supposed to be earlier
+    still, and as the Sequoias have not outgrown the fire-scars in
+    all that time, they are supposed to have then arrived at their
+    full growth. But the simple explanation of these trees alone
+    having suffered so much from fire is, that their bark is
+    unusually thick, dry, soft, and fibrous, <span class=
+    "pagenum"><a name="page122"
+       id="page122"></a>[pg 122]</span> and it thus catches fire
+       more easily and burns more readily and for a longer time
+       than that of the other coniferæ. Forest fires occur
+       continually, and the visible damage done to these trees has
+       probably all occurred in the present century. Professor C.B.
+       Bradley, of the University of California, has carefully
+       counted the rings of annual growth on the stump of the
+       "Pavilion tree," and found them to be twelve hundred and
+       forty; and after considering all that has been alleged as to
+       the uncertainty of this mode of estimating <span class=
+       "pagenum"><a name="page123"
+       id="page123"></a>[pg 123]</span> the age of a tree, he
+       believes that in the climate of California, in the zone of
+       altitude where these trees grow, the seasons of growth and
+       repose are so strongly marked that the number of annual
+       rings gives an accurate result.</p>
+
+    <p>Other points that have been studied by Professor Bradley
+    are, the reason why there are so few young trees in the groves,
+    and what is the cause of the destruction of the old trees. To
+    take the last point first, these noble trees seem to be
+    singularly free from disease or from decay due to old age. All
+    the trees that have been cut down are solid to the heart, and
+    none of the standing trees show any indications of natural
+    decay. The only apparent cause for their overthrow is the wind,
+    and by noting the direction of a large number of fallen trees
+    it is found that the great majority of them lie more or less
+    towards the south. This is not the direction of the prevalent
+    winds, but many of the tallest trees lean towards the south,
+    owing to the increased growth of their topmost branches towards
+    the sun. They are then acted upon by violent gales, which
+    loosen their roots, and whatever the direction of the wind that
+    finally overthrows them, they fall in the direction of the
+    over-balancing top weight. The young trees grow spiry and
+    perfectly upright, but as soon as they overtop the surrounding
+    trees and get the full influence of the sun and wind, the
+    highest branches grow out laterally, killing those beneath
+    their shade, and thus a dome-shaped top is produced. Taking
+    into consideration the health and vigor of the largest trees,
+    it seems probable that, under favorable conditions of shelter
+    from violent winds, and from a number of trees
+          <span class="pagenum"><a name="page124"
+       id="page124"></a>[pg 124]</span> around them of nearly equal
+       height, big trees might be produced far surpassing in height
+       and bulk any that have yet been discovered. It is to be
+       hoped that if any such are found to exist in the extensive
+       groves of these trees to the south of those which are alone
+       accessible to tourists, the Californian Government will take
+       steps to reserve a considerable tract containing them, for
+       the instruction and delight of future generations.</p>
+
+    <p>The scarcity of young Sequoias strikes every visitor, the
+    fact being that they are only to be found in certain favored
+    spots. These are, either where the loose débris of leaves and
+    branches which covers the ground has been cleared away by fire,
+    or on the spots where trees have been uprooted. Here the young
+    trees grow in abundance, and serve to replace those that fall.
+    The explanation of this is, that during the long summer drought
+    the loose surface débris is so dried up that the roots of the
+    seedling Sequoias perish before they can penetrate the earth
+    beneath. They require to germinate on the soil itself, and this
+    they are enabled to do when the earth is turned up by the fall
+    of a tree, or where a fire has cleared off the débris. They
+    also flourish under the shade of the huge fallen trunks in
+    hollow places, where moisture is preserved throughout the
+    summer. Most of the other conifers of these forests, especially
+    the pines, have much larger seeds than the Sequoias, and the
+    store of nourishment in these more bulky seeds enables the
+    young plants to tide over the first summer's drought. It is
+    clear, therefore, that there are no indications of natural
+    decay in these forest giants. In every stage of their growth
+    they are vigorous <span class="pagenum"><a name="page125"
+       id="page125"></a>[pg 125]</span> and healthy, and they have
+       nothing to fear except from the destroying hand of man.</p>
+
+    <div class="figright"
+         style="width:350px;">
+        <a href="images/125.png"><img width="350"
+             src="images/125.png"
+             alt="REDWOOD TREE WITH TRIPLE TRUNK." /></a><br />
+        REDWOOD TREE WITH TRIPLE TRUNK.
+    </div>
+
+    <p>Destruction from this cause is, however, rapidly diminishing
+    both the giant Sequoia and its near ally the noble redwood
+    (<i>Sequoia sempervirens</i>), a tree which is more beautiful
+    in foliage and in some other respects more remarkable than its
+    brother species, while there is reason to believe that under
+    favorable conditions it reaches an equally phenomenal size. It
+    once covered almost all the coast ranges of central and
+    northern California, but has been long since cleared away in
+    the vicinity of San Francisco, and greatly diminished
+    elsewhere. A grove is preserved for the benefit of tourists
+    near Santa Cruz, the largest tree being two hundred and
+    ninety-six feet high, twenty-nine feet diameter at the ground
+    and fifteen feet at six feet above it. One of these trees
+    having a triple trunk is here figured from a photograph. Much
+    larger trees, however, exist in the great forests of this tree
+    in the northern part of the State; but <span class=
+    "pagenum"><a name="page126"
+       id="page126"></a>[pg 126]</span> these are rapidly being
+       destroyed for the timber, which is so good and durable as to
+       be in great demand. Hence Californians have a saying that
+       the redwood is too good a tree to live. On the mountains a
+       few miles east of the Bay of San Francisco, there are a
+       number of patches of young redwoods, indicating where large
+       trees have been felled, it being a peculiarity of this tree
+       that it sends up vigorous young plants from the roots of old
+       ones immediately around the base. Hence in the forests these
+       trees often stand in groups arranged nearly in a circle,
+       thus marking out the size of the huge trunks of their
+       parents. It is from this quality that the tree has been
+       named <i>sempervirens</i>, or ever flourishing. Dr. Gibbons,
+       of Alameda, who has explored all the remains of the redwood
+       forests in the neighborhood of Oakland, kindly took me to
+       see the old burnt-out stump of the largest tree he had
+       discovered. It is situated about fifteen hundred feet above
+       the sea, and is thirty-four feet in diameter at the ground.
+       This is as large as the very largest specimens of the
+       <i>Sequoia gigantea</i>, but it may have spread out more at
+       the base and have been somewhat smaller above, though this
+       is not a special characteristic of the
+          species.</p><br clear="all" />
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/126.png"><img width="500"
+             src="images/126.png"
+             alt="Sequoias." /></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="page127"
+       id="page127"></a>[pg 127]</span>
+
+    <h2>WHAT IS EVOLUTION?</h2>
+
+    <h4>(<span class="sc">From The Atlantic Monthly, March,
+    '93.</span>)</h4>
+
+    <h3><span class="sc">By</span> PROFESSOR E.S. HOLDEN.</h3>
+    <hr class="short" />
+
+    <div class="figleft"
+         style="width:150px;">
+        <a href="images/127.png"><img width="150"
+             src="images/127.png"
+             alt="Oak tree." /></a>
+    </div>
+
+    <p>I was once trying to tell a boy, a friend of mine, what the
+    scientific men mean by the long word <i>Evolution</i>, and to
+    give him some idea of the plan of the world. I wanted an
+    illustration of something that had grown&mdash;evolved,
+    developed&mdash;from small beginnings up through more and more
+    complicated forms, till it had reached some very complete form.
+    I could think of no better example than the railway by which we
+    were sitting. The trains were running over the very track where
+    a wagon-road had lately been, and before that a country
+    cart-track, and before that a bridle-path, and before that
+    again a mere trail for cattle. So I took the road for an
+    example, and tried to show my boy how it had grown from little
+    things by slow degrees according to laws; and if you like, I
+    will try to tell it again.</p>
+
+    <p>Just as one can go further and further back, and always find
+    a bird to be the parent of the egg, and an egg to be the parent
+    of that bird, so in the history of <span class=
+    "pagenum"><a name="page128"
+       id="page128"></a>[pg 128]</span> this road of ours; we may
+       go back and back into the past, always finding something
+       earlier, which is the cause of the something later. The
+       earth, the planets, and the sun were all a fiery mist long
+       ago. And in that mist, and in what came before it, we may
+       look for the origin of things as they are. But we must begin
+       somewhere. Let us begin with the landscape as we see it
+       now,&mdash;hills, valleys, streams, mountains,
+       grass,&mdash;but with only a single tree.</p>
+
+    <p>We will not try to say how the tree came there. At least, we
+    will not try just yet. When we are through with the story you
+    can say just as well as I can.</p>
+
+    <p>Suppose, then, a single oak-tree stood just on that hillside
+    thousands and thousands of years ago. Grass was growing
+    everywhere, and flowers, too. The seeds came with the winds.
+    Year after year the oak-tree bore its acorns, hundreds and
+    hundreds of them, and they fell on the grass beneath and rolled
+    down the smooth slopes, and sprouted as best they
+    could,&mdash;most of them uselessly so far as producing trees
+    were concerned,&mdash;but each one did its duty and furnished
+    its green sprout, and died if it found no nourishment.</p>
+
+    <p>All the hundreds of acorns rolled down the slopes, Not one
+    rolled up; and here was a <i>law</i>,&mdash;the law of
+    gravitation,&mdash;in full activity. There were scores of other
+    laws active, too; for evolution had gone a long way when we had
+    an earth fit to be lived on, and hills in their present shape,
+    and a tree bearing acorns that would reproduce their kind. But
+    ever since the fiery mist this simple law of gravitation has
+    been acting, binding the whole universe together, making a
+    relationship between each clod and every other clod, and
+    <span class="pagenum"><a name="page129"
+       id="page129"></a>[pg 129]</span> forcing every stone, every
+       acorn, and every rain-drop to move down and not up.</p>
+
+    <p>Just as this law operates,&mdash;continuously, silently,
+    inexorably,&mdash;so every other law makes itself felt in its
+    own sphere. Gravitation is simple. The law according to which
+    an acorn makes an oak&mdash;and not a pine-tree is complex. But
+    the laws of Nature are all alike, and if we understand the
+    simple ones, we can at least partly comprehend the more
+    complex. They are nothing but fixed habits on a large
+    scale.</p>
+
+    <p>So the acorns fell year by year and sprouted; and one out of
+    a thousand found good soil, and was not wasted, and made a
+    tree. And so all around (below) the tree with which we started
+    there grew a grove of oaks like it, in fact its children; and
+    finally the original trees died, but not without having left
+    successors.</p>
+
+    <p>First of all, the green hillside is smooth and untrodden.
+    There is nothing but grass and flowers, borne there by the
+    winds, which leave no track. There is no animal life even in
+    this secluded spot save the birds, and they too leave no track.
+    By and by there comes a hard winter, or a dearth of food, and a
+    pair of stray squirrels emigrate from their home in the valley
+    below; and the history of our hill and its woods begins. Mere
+    chance decides the choice of the particular oak-tree in which
+    the squirrels make their home. From the foot of this tree they
+    make excursions here and there for their store of winter
+    food,&mdash;acorns and the like,&mdash;and they leave little
+    paths on the hillside from tree to tree.</p>
+
+    <p>The best-marked paths run to the places where there are the
+    most acorns. A little later on there are more squirrels in the
+    colony,&mdash;the young of the parent pair, <span class=
+    "pagenum"><a name="page130"
+       id="page130"></a>[pg 130]</span> and other colonists from
+       the valley. The little tracks become plainer and
+       plainer.</p>
+
+    <p>Later still come other wild animals in search of
+    food,&mdash;squirrels will do. The wild animals do not remain
+    in the colony (there are too few squirrels, and they are too
+    hard to catch), but they pass through it, sometimes by day but
+    oftenest by night.</p>
+
+    <p>You might think it was perfectly a matter of chance along
+    which path a bear or a wolf passed, but it was not. He
+    <i>could</i> walk anywhere on the hillside; and sometimes he
+    would be found far out of the paths that the squirrels had
+    begun. But usually, when he was in no haste, he took the
+    easiest path. The easiest one was that which went between the
+    bushes and not through them; along the hillside and not
+    straight up it; around the big rocks and not over them. The
+    wolves and bears and foxes have new and different wants when
+    they come; and they break new paths to the springs where they
+    drink, to the shade where they lie, to the hollow trees where
+    the bees swarm and store the wild honey.</p>
+
+    <p>But the squirrels were the first surveyors of these tracks.
+    The bears and wolves are the engineers, who change the early
+    paths to suit their special convenience.</p>
+
+    <p>By and by the Indian hunter comes to follow the wild game.
+    He, too, takes the easiest trail, the path of least resistance;
+    and he follows the track to the spring that the deer have made,
+    and he drinks there. He is an animal as they are, and he
+    satisfies his animal wants according to the same law that
+    governs them.</p>
+
+    <p>After generations of hunters, Indians, and then white men,
+    there comes a man on horseback looking for a <span class=
+    "pagenum"><a name="page131"
+       id="page131"></a>[pg 131]</span> house to live in. He, too,
+       follows along the easiest paths and stops at the spring; and
+       near by he finds the place he is looking for. Soon he
+       returns, driving before him herds of cattle and flocks of
+       sheep, which spread over the grassy glades to feed. But
+       everywhere they take the easiest place, the old paths, from
+       the shady tree to the flowing spring. After awhile the
+       hillside is plainly marked with these sheep trails. You can
+       see them now whenever you go into the country, on every
+       hillside.</p>
+
+    <p>Soon there are neighbors who build their homes in the next
+    valley, and a good path must be made between the different
+    houses.</p>
+
+    <p>A few days' work spent in moving the largest stones, in
+    cutting down trees, and in levelling off a few steep slopes,
+    makes a trail along which you can gallop your horse.</p>
+
+    <p>Things move fast now,&mdash;history begins to be made
+    quickly as soon as man takes a hand in it. Soon the trail is
+    not enough: it must be widened so that a wagon-load of boards
+    for a new house can be carried in (for the settler has found a
+    wife). After the first cart-track is made to carry the boards
+    and shingles in, a better road will be needed to haul firewood
+    and grain out (for the wants of the new family have increased,
+    and things must be bought in the neighboring village with
+    money, and money can only be had by selling the products of the
+    farm). By and by the neighborhood is so well inhabited that it
+    is to the advantage of the villages all around it to have good
+    and safe and easy roads there; and the road is declared a
+    public one, and it is regularly kept in repair and improved at
+    the public <span class="pagenum"><a name="page132"
+       id="page132"></a>[pg 132]</span> expense. Do not forget the
+       squirrels of long ago. They were the projectors of this
+       road. Their successors use it now,&mdash;men and squirrels
+       alike,&mdash;and stop at the spring to drink, and under the
+       huge oaks to rest.</p>
+
+    <p>A few years more, and it becomes to the advantage of all to
+    have a railway through the valley and over the hillside. Then a
+    young surveyor, just graduated from college, comes with his
+    chain-men and flag-men, and finds that the squirrels, and
+    bears, and hunters, and all the rest have picked out the
+    easiest way for him long centuries ago. He makes his map, and
+    soon the chief enigneer and the president of the road drive
+    along in a buggy with a pair of fast horses (frightening the
+    little squirrels off their road-way and into their holes), and
+    the route of the Bear Valley and Quercus Railway is finally
+    selected, and here it is. See! there comes a train along the
+    track. This is the way a railway route grew out of a squirrel
+    path. There are thousands of little steps, but you can trace
+    them, or imagine them, as well as I can tell you.</p>
+
+    <p>It is the same all over the world. Stanley cut a track
+    through the endless African forests. But it lay between the
+    Pygmy villages, along the paths they had made, and through the
+    glades where they fought their battles with the storks.</p>
+
+    <p>Sometimes the first road is a river&mdash;the track is
+    already cut. Try to find out where the settlements in America
+    were in the very early days&mdash;before 1800. You will find
+    them along the Hudson, the Juanita, the St. Lawrence, the
+    James, the Mississippi Rivers. But when these are left, men
+    follow the squirrel-tracks and <span class=
+       "pagenum"><a name="page133"
+       id="page133"></a>[pg 133]</span> bear-tracks, or the paths
+       of hunters, or the roads of Roman soldiers. It is a standing
+       puzzle to little children why all the great rivers flow past
+       the great towns. (Why do they?) The answer to that question
+       will tell you why the great battles are fought in the same
+       regions; why Egypt has been the coveted prize of a dozen
+       different conquerors (it is the gateway of the East); why
+       our Civil War turned on the possession of the Mississippi
+       River. It is the roadways we fight for, the ways in and out,
+       whether they be land or water. Of course, we really fought
+       for something better than the mere possession of a roadway,
+       but to get what we fought for we had to have the roadway
+       first.</p>
+
+    <p>The great principle at the bottom of everything in Nature is
+    that the fittest survives: or, as I think it is better to say
+    it, in any particular conflict or struggle that thing survives
+    which is the fittest to survive <i>in this particular
+    struggle</i>. This is Mr. Darwin's discovery,&mdash;or one of
+    them,&mdash;and the struggle for existence is a part of the
+    great struggle of the whole universe, and the laws of it make
+    up the methods of Evolution&mdash;of Development.</p>
+
+    <p>It is clear now, is it not, how the railway route is the
+    direct descendant of the tiny squirrel track between two oaks?
+    The process of development we call Evolution, and you can trace
+    it all around you. Why are your skates shaped in a certain way?
+    Why is your gun rifled? Why have soldiers two sets of (now)
+    useless buttons on the skirts of their coats? (I will give you
+    three guesses for this, and the hint that you must think of
+    cavalry soldiers.) Why are eagles' wings of just the size that
+    they are? These and millions <span class="pagenum"><a name=
+    "page134"
+       id="page134"></a>[pg 134]</span> of like questions are to be
+       answered by referring to the principle of development.</p>
+
+    <p>Sometimes it is hard to find the clew. Sometimes the
+    development has gone so far, and the final product has become
+    so complex and special, that it takes a good deal of thinking
+    to find out the real reasons. But they <i>can</i> be found,
+    whether they relate to a fashion, to one of the laws of our
+    country, or to the colors on a butterfly's wing.</p>
+
+    <p>There is a little piece of verse intended to be comic,
+    which, on the contrary, is really serious and philosophical, if
+    you understand it. Learn it by heart, and apply it to all kinds
+    and conditions of things, and see if it does not help you to
+    explain them to yourself....</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p>"And Man grew a thumb for that he had need of
+            it,</p>
+
+            <p>And developed capacities for prey.</p>
+
+            <p>For the fastest men caught the most animals,</p>
+
+            <p>And the fastest animals got away from the most
+            men.</p>
+
+            <p>Whereby all the slow animals were eaten,</p>
+
+            <p>And all the slow men starved to death."</p>
+        </div>
+    </div>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/134.png"><img width="500"
+             src="images/134.png"
+             alt="Train engine." /></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="page135"
+       id="page135"></a>[pg 135]</span>
+
+    <h2>HOW THE SOIL IS MADE</h2>
+
+    <h4>(<span class="sc">From the Formation of Vegetable
+    Mould.</span>)</h4>
+
+    <h3><span class="sc">By</span> CHARLES DARWIN.</h3>
+    <hr class="short" />
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/135.png"><img width="200"
+             src="images/135.png"
+             alt="Worms." /></a>
+    </div>
+
+    <p>Worms have played a more important part in the history of
+    the world than most persons would at first suppose. In almost
+    all humid countries they are extraordinarily numerous, and for
+    their size possess great muscular power. In many parts of
+    England a weight of more than ten tons (10,516 kilogrammes) of
+    dry earth annually passes through their bodies and is brought
+    to the surface on each acre of land; so that the whole
+    superficial bed of vegetable mould passes through their bodies
+    in the course of every few years. From the collapsing of the
+    old burrows the mould is in constant though slow movement, and
+    the particles composing it are thus rubbed together. By these
+    means fresh surfaces are continually exposed to the action of
+    the carbonic acid in the soil, and of the humus-acids which
+    appear to be still more efficient in the decomposition of
+    rocks. The generation of the humus-acids is probably hastened
+    <span class="pagenum"><a name="page136"
+       id="page136"></a>[pg 136]</span> during the digestion of the
+       many half-decayed leaves which worms consume. Thus the
+       particles of earth, forming the superficial mould, are
+       subjected to conditions eminently favorable for their
+       decomposition and disintegration. Moreover, the particles of
+       the softer rocks suffer some amount of mechanical
+       trituration in the muscular gizzards of worms, in which
+       small stones serve as mill-stones.</p><br clear="all" />
+
+    <div class="figleft"
+         style="width:175px;">
+        <a href="images/136.png"><img width="175"
+             src="images/136.png"
+             alt=
+           "DIAGRAM OF THE ALIMENTARY CANAL OF AN EARTH-WORM." /></a><br />
+        DIAGRAM OF THE ALIMENTARY CANAL OF AN EARTH-WORM.
+    </div>
+
+    <p>The finely levigated castings, when brought to the surface
+    in a moist condition, flow during rainy weather down any
+    moderate slope; and the smaller particles are washed far down
+    even a gently inclined surface. Castings when dry often crumble
+    into small pellets and these are apt to roll down any sloping
+    surface. Where the land is quite level and is covered with
+    herbage, and where the climate is humid so that much dust
+    cannot be blown away, it appears at first sight impossible that
+    there should be any appreciable amount of sub-aerial
+    denudation; but worm castings are blown, especially while moist
+    and viscid, in one uniform direction by the prevalent winds
+    which are accompanied by rain. By these several means the
+    superficial mould is prevented from accumulating to a great
+    thickness; and a thick bed of mould checks in many ways the
+    disintegration of the underlying rocks and fragments of
+    rock.</p><span class="pagenum"><a name="page137"
+       id="page137"></a>[pg 137]</span>
+
+    <div class="figright"
+         style="width:250px;">
+        <a href="images/137.png"><img width="250"
+             src="images/137.png"
+             alt="A WORM CASTING, FROM NICE." /></a>
+
+        <p>A WORM CASTING, FROM NICE. (Natural Size.)</p>
+    </div>
+
+    <p>The removal of worm-castings by the above means leads to
+    results which are far from insignificant. It has been shown
+    that a layer of earth,.2 of an inch in thickness, is in many
+    places annually brought to the surface per acre; and if a small
+    part of this amount flows, or rolls, or is washed, even for a
+    short distance, down every inclined surface, or is repeatedly
+    blown in one direction, a great effect will be produced in the
+    course of ages. It was found by measurements and calculations
+    that on a surface with a mean inclination of 9° 26', 2.4 cubic
+    inches of earth which had been ejected by worms crossed, in the
+    course of a year, a horizontal line one yard in length; so that
+    two hundred and forty cubic inches would cross a line one
+    hundred yards in length. This latter amount in a damp state
+    would weigh eleven and one-half pounds. Thus, a considerable
+    weight of earth is continually moving down each side of every
+    valley, and will in time reach its bed. Finally, this earth
+    will be transported by the streams flowing in the valleys into
+    the ocean, the great receptacle for all matter denuded from the
+    land. It is known from the amount of sediment annually
+    delivered into the sea by the Mississippi, <span class=
+    "pagenum"><a name="page138"
+       id="page138"></a>[pg 138]</span> that its enormous
+       drainage-area must on an average be lowered.00263 of an inch
+       each year; and this would suffice in four and a half million
+       years to lower the whole drainage-area to the level of the
+       seashore. So that if a small fraction of the layer of fine
+       earth,.2 of an inch in thickness, which is annually brought
+       to the surface by worms, is carried away, a great result
+       cannot fail to be produced within a period which no
+       geologist considers extremely long.</p>
+
+    <div class="figleft"
+         style="width:400px;">
+        <a href="images/138.png"><img width="400"
+             src="images/138.png"
+             alt=
+           "SECTION THROUGH ONE OF THE DRUIDICAL STONES AT STONEHENGE, SHOWING HOW MUCH IT HAD SUNK INTO THE GROUND." /></a>
+
+        <p>SECTION THROUGH ONE OF THE DRUIDICAL STONES AT
+        STONEHENGE, SHOWING HOW MUCH IT HAD SUNK INTO THE
+        GROUND.</p>(Scale, ½ inch to 1 foot.)
+    </div>
+
+    <p>Archaeologists ought to be grateful to worms, as they
+    protect and preserve for an indefinitely long period every
+    object, not liable to decay, which is dropped on the surface of
+    the land, by burying it beneath their castings. Thus, also,
+    many elegant and curious tesselated pavements and other ancient
+    remains have been preserved; though no doubt the worms have in
+    these cases been largely aided by earth washed and blown from
+    the adjoining land, especially when cultivated. The old
+    tesselated pavements have, however, often suffered by having
+    subsided unequally from being unequally undermined by the
+    worms. Even old massive walls may be undermined and subside;
+    and no building is in this respect safe, unless the foundations
+    lie six or seven feet beneath the surface, at a depth at which
+    worms cannot work. It is probable that many <span class=
+    "pagenum"><a name="page139"
+       id="page139"></a>[pg 139]</span> monoliths and some old
+       walls have fallen down from having been undermined by
+       worms.</p>
+
+    <p>Worms prepare the ground in an excellent manner for the
+    growth of fibrous-rooted plants and for seedlings of all kinds.
+    They periodically expose the mould to the air, and sift it so
+    that no stones larger than the particles which they can swallow
+    are left in it. They mingle the whole intimately together, like
+    a gardener who prepares fine soil for his choicest plants. In
+    this state it is well fitted to retain moisture and to absorb
+    all soluble substances, as well as for the process of
+    nitrification. The bones of dead animals, the harder parts of
+    insects, the shells of land mollusks, leaves, twigs, etc., are
+    before long all buried beneath the accumulated castings of
+    worms, and are thus brought in a more or less decayed state
+    within reach of the roots of plants. Worms likewise drag an
+    infinite number of dead leaves and other parts of plants into
+    their burrows, partly for the sake of plugging them up and
+    partly as food.</p>
+
+    <p>The leaves which are dragged into the burrows as food, after
+    being torn into the finest shreds, partially digested and
+    saturated with the intestinal and urinary secretions, are
+    commingled with much earth. This earth forms the dark-colored,
+    rich humus which almost everywhere covers the surface of the
+    land with a fairly well-defined layer or mantle. Von Hensen
+    placed two worms in a vessel eighteen inches in diameter, which
+    was filled with sand, on which fallen leaves were strewed; and
+    these were soon dragged into their burrows to a depth of three
+    inches. After about six weeks an almost uniform layer of sand,
+    a centimetre <span class="pagenum"><a name="page140"
+       id="page140"></a>[pg 140]</span> (.4 inch) in thickness, was
+       converted into humus by having passed through the alimentary
+       canals of these two worms. It is believed by some persons
+       that worm-burrows, which often penetrate the ground almost
+       perpendicularly to a depth of five or six feet, materially
+       aid in its drainage; notwithstanding that the viscid
+       castings piled over the mouths of the burrows prevent or
+       check the rain-water directly entering them. They allow the
+       air to penetrate deeply into the ground. They also greatly
+       facilitate the downward passage of roots of moderate size;
+       and these will be nourished by the humus with which the
+       burrows are lined. Many seeds owe their germination to
+       having been covered by castings; and others buried to a
+       considerable depth beneath accumulated castings lie dormant,
+       until at some future time they are accidentally uncovered
+       and germinate.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/140.png"><img width="300"
+             src="images/140.png"
+             alt="A WORM CASTING FROM SOUTH INDIA." /></a>
+
+        <p>A WORM CASTING FROM SOUTH INDIA.</p>(Natural Size.)
+    </div>
+
+    <p>Worms are poorly provided with sense-organs, for they cannot
+    be said to see, although they can just distinguish between
+    light and darkness; they are completely deaf, and have only a
+    feeble power of smell; the sense of touch alone is well
+    developed. They can, therefore, learn little about the outside
+    world, and it is surprising that they should exhibit some skill
+    in lining <span class="pagenum"><a name="page141"
+       id="page141"></a>[pg 141]</span> their burrows with their
+       castings and with leaves, and in the case of some species in
+       piling up their castings into tower-like constructions. But
+       it is far more surprising that they should apparently
+       exhibit some degree of intelligence instead of a mere blind,
+       instinctive impulse, in their manner of plugging up the
+       mouths of their burrows. They act in nearly the same manner
+       as would a man, who had to close a cylindrical tube with
+       different kinds of leaves, petioles, triangles of paper,
+       etc., for they commonly seize such objects by their pointed
+       ends. But with thin objects a certain number are drawn in by
+       their broader ends. They do not act in the same unvarying
+       manner in all cases, as do most of the lower animals; for
+       instance, they do not drag in leaves by their foot-stalks,
+       unless the basil part of the blade is as narrow as the apex,
+       or narrower than it.</p>
+    <hr />
+
+    <p>When we behold a wide, turf-covered expanse, we should
+    remember that its smoothness, on which so much of its beauty
+    depends, is mainly due to all the inequalities having been
+    slowly levelled by worms. It is a marvellous reflection that
+    the whole of the superficial mould over any such expanse has
+    passed, and will again pass, every few years through the bodies
+    of worms. The plough is one of the most ancient and most
+    valuable of man's inventions; but long before he existed the
+    land was in fact regularly ploughed, and, still continues to be
+    thus ploughed by earth-worms. It may be doubted whether there
+    are many other animals which have played so important a part in
+    the history of the world, as have these lowly organized
+    creatures. Some <span class="pagenum"><a name="page142"
+       id="page142"></a>[pg 142]</span> other animals, however,
+       still more lowly organized, namely, corals, have done far
+       more conspicuous work in having constructed innumerable
+       reefs and islands in the great oceans; but these are almost
+       confined to the tropical zones.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/142.png"><img width="500"
+             src="images/142.png"
+             alt="Mountain peak." /></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="page143"
+       id="page143"></a>[pg 143]</span>
+
+    <h2>ZOÖLOGICAL MYTHS</h2>
+
+    <h4>(<span class="sc">From Facts and Fictions of
+    ZoÖlogy.</span>)</h4>
+
+    <h3><span class="sc">By</span> ANDREW WILSON.</h3>
+    <hr class="short" />
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/143.png"><img width="250"
+             src="images/143.png"
+             alt="Mermaid." /></a>
+    </div>
+
+    <p>When the country swain, loitering along some lane, comes to
+    a standstill to contemplate, with awe and wonder, the spectacle
+    of a mass of the familiar "hair-eels" or "hair-worms" wriggling
+    about in a pool, he plods on his way firmly convinced that, as
+    he has been taught to believe, he has just witnessed the
+    results of the transformation of some horse's hairs into living
+    creatures. So familiar is this belief to people of professedly
+    higher culture than the countryman, that the transformation
+    just alluded to has to all, save a few thinking persons and
+    zoölogists, become a matter of the most commonplace kind. When
+    some quarrymen, engaged in splitting up the rocks, have
+    succeeded in dislodging some huge mass of stone, there may
+    sometimes be seen to hop from among the débris a lively toad or
+    frog, which comes to be regarded by the excavators with
+    feelings akin to those of <span class="pagenum"><a name=
+    "page144"
+       id="page144"></a>[pg 144]</span> superstitious wonder and
+       amazement. The animal may or may not be captured; but the
+       fact is duly chronicled in the local newspapers, and people
+       wonder for a season over the phenomenon of a veritable Rip
+       Van Winkle of a frog, which to all appearance, has lived for
+       "thousands of years in the solid rock." Nor do the hair-worm
+       and the frog stand alone in respect of their marvellous
+       origin. Popular zoölogy is full of such marvels. We find
+       unicorns, mermaids, and mermen; geese developed from the
+       shell-fish known as "barnacles"; we are told that crocodiles
+       may weep, and that sirens can sing&mdash;in short, there is
+       nothing so wonderful to be told of animals that people will
+       not believe the tale. Whilst, curiously enough, when they
+       are told of veritable facts of animal life, heads begin to
+       shake and doubts to be expressed, until the zoölogist
+       despairs of educating people into distinguishing fact from
+       fiction, and truth from theories and unsupported beliefs.
+       The story told of the old lady, whose youthful acquaintance
+       of seafaring habits entertained her with tales of the
+       wonders he had seen, finds, after all, a close application
+       in the world at large. The dame listened with delight,
+       appreciation, and belief, to accounts of mountains of sugar
+       and rivers of rum, and to tales of lands where gold and
+       silver and precious stones were more than plentiful. But
+       when the narrator descended to tell of fishes that were able
+       to raise <span class="pagenum"><a name="page145"
+       id="page145"></a>[pg 145]</span> themselves out of the water
+       in flight, the old lady's credulity began to fancy itself
+       imposed upon; for she indignantly repressed what she
+       considered the lad's tendency to exaggeration, saying,
+       "Sugar mountains may be, and rivers of rum may be, but fish
+       that flee ne'er can be!" Many popular beliefs concerning
+       animals partake of the character of the old lady's opinions
+       regarding the real and fabulous; and the circumstance tells
+       powerfully in favor of the opinion that a knowledge of our
+       surroundings in the world, and an intelligent conception of
+       animal and plant life, should form part of the
+       school-training of every boy and girl, as the most effective
+       antidote to superstitions and myths of every kind.</p>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/144.png"><img width="400"
+             src="images/144.png"
+             alt="FLYING FISH." /></a><br />
+        FLYING FISH.
+    </div>
+
+    <p>The tracing of myths and fables is a very interesting task,
+    and it may, therefore, form a curious study, if we endeavor to
+    investigate very briefly a few of the popular and erroneous
+    beliefs regarding lower animals. The belief regarding the
+    origin of the hair-worms is both widely spread and ancient.
+    Shakespeare tells us that</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p class="i22">"Much, is breeding</p>
+
+            <p>Which, like the courser's hair, hath, yet but
+            life,</p>
+
+            <p>And not a serpent's poison."</p>
+        </div>
+    </div>
+
+    <p>The hair-worms certainly present the appearance of long,
+    delicate black hairs, which move about with great activity
+    amidst the mud of pools and ditches. These worms, in the early
+    stages of their existence, inhabit the bodies of insects, and
+    may be found coiled up within the grasshopper, which thus gives
+    shelter to a guest exceeding many times the length of the body
+    of its host. Sooner or later the hair-worm, or <i>Gordius</i>
+    <span class="pagenum"><a name="page146"
+       id="page146"></a>[pg 146]</span> <i>aquaticus</i> as the
+       naturalist terms it, leaves the body of the insect, and lays
+       its eggs, fastened together in long strings, in water. From
+       each egg a little creature armed with minute hooks is
+       produced, and this young hair-worm burrows its way into the
+       body of some insect, there to repeat the history of its
+       parent. Such is the well-ascertained history of the
+       hair-worm, excluding entirely the popular belief in its
+       origin. There certainly does exist in science a theory known
+       as that of "spontaneous generation," which, in ancient
+       times, accounted for the production of insects and other
+       animals by assuming that they were produced in some
+       mysterious fashion out of lifeless matter. But not even the
+       most ardent believer in the extreme modification of this
+       theory which holds a place in modern scientific belief,
+       would venture to maintain the production of a hair-worm by
+       the mysterious vivification of an inert substance such as a
+       horse's hair.</p>
+
+    <p>The expression "crocodile's tears" has passed into common
+    use, and it therefore may be worth while noting the probable
+    origin of this myth. Shakespeare, with that wide extent of
+    knowledge which enabled him to draw similes from every
+    department of human thought, says that</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p class="i22">"Gloster's show</p>
+
+            <p>Beguiles him, as the mournful crocodile</p>
+
+            <p>With sorrow snares relenting passengers."</p>
+        </div>
+    </div>
+
+    <p>The poet thus indicates the belief that not only do
+    crocodiles shed tears, but that sympathizing passengers,
+    turning to commiserate the reptile's woes, are seized and
+    destroyed by the treacherous creatures. That quaint and
+    credulous old author&mdash;the earliest writer
+          <span class="pagenum"><a name="page147"
+       id="page147"></a>[pg 147]</span> of English prose&mdash;Sir
+       John Mandeville, in his "Voiage," or account of his
+       "Travile," published about 1356&mdash;in which, by the way,
+       there are to be found accounts of not a few wonderful things
+       in the way of zoölogical curiosities&mdash;tells us that in
+       a certain "contre and be all yonde, ben great plenty of
+       Crokodilles, that is, a manner of a long Serpent as I have
+       seyed before." He further remarks that "these Serpents slew
+       men," and devoured them, weeping; and he tells us, too, that
+       "whan thei eaten thei meven (move) the over jowe (upper
+       jaw), and nought the nether (lower) jowe: and thei have no
+       tonge (tongue)." Sir John thus states two popular beliefs of
+       his time and of days prior to his age, namely, that
+       crocodiles move their upper jaws, and that a tongue was
+       absent in these animals.</p>
+
+    <div class="figright"
+         style="width:400px;">
+        <a href="images/147.png"><img width="400"
+             src="images/147.png"
+             alt="CROCODILE." /></a><br />
+        CROCODILE.
+    </div>
+
+    <p>As regards the tears of the crocodile, no foundation of fact
+    exists for the belief in such sympathetic exhibitions. But a
+    highly probable explanation may be given of the manner in which
+    such a belief originated. These reptiles unquestionably emit
+    very loud and singularly plaintive cries, compared by some
+    travellers to the mournful howling of dogs. The earlier and
+    credulous <span class="pagenum"><a name="page148"
+       id="page148"></a>[pg 148]</span> travellers would very
+       naturally associate tears with these cries, and, once begun,
+       the supposition would be readily propagated, for error and
+       myth are ever plants of quick growth. The belief in the
+       movement of the upper jaw rests on apparent basis of fact.
+       The lower jaw is joined to the skull very far back on the
+       latter, and the mouth-opening thus comes to be singularly
+       wide; whilst, when the mouth opens, the skull and upper jaw
+       are apparently observed to move. This is not the case,
+       however; the apparent movement arising from the manner in
+       which the lower jaw and the skull are joined together. The
+       belief in the absence of the tongue is even more readily
+       explained. When the mouth is widely opened, no tongue is to
+       be seen. This organ is not only present, but is, moreover,
+       of large size; it is, however, firmly attached to the floor
+       of the mouth, and is specially adapted, from its peculiar
+       form and structure, to assist these animals in the capture
+       and swallowing of their prey.</p>
+
+    <p>One of the most curious fables regarding animals which can
+    well be mentioned, is that respecting the so-called "Bernicle"
+    or "Barnacle Geese," which by the naturalists and educated
+    persons of the Middle Ages were believed to be produced by
+    those little Crustaceans named "Barnacles." With the
+    "Barnacles" every one must be familiar who has examined the
+    floating driftwood of the sea-beach, or who has seen ships
+    docked in a seaport town. A barnacle is simply a kind of crab
+    enclosed in a triangular shell, and attached by a fleshy stalk
+    to fixed objects. If the barnacle is not familiar to readers,
+    certain near relations of these animals must be well known, by
+    sight at least, as amongst the most <span class=
+    "pagenum"><a name="page149"
+       id="page149"></a>[pg 149]</span> familiar denizens of our
+       sea-coast. These latter are the "Sea-Acorn," or Balani,
+       whose little conical shells we crush by hundreds as we walk
+       over the rocks at low-water mark; whilst every wooden pile
+       immersed in the sea becomes coated in a short time with a
+       thick crust of the "Sea-Acorns." If we place one of these
+       little animals, barnacle, or sea-acorn&mdash;the latter
+       wanting the stalk of the former&mdash;in its native waters,
+       we shall observe a beautiful little series of feathery
+       plumes to wave backward and forward, and ever and anon to be
+       quickly withdrawn into the secure recesses of the shell.
+       These organs are the modified feet of the animal, which not
+       only serve for sweeping food-particles into the mouth, but
+       act also as breathing-organs. We may, therefore, find it a
+       curious study to inquire through what extraordinary
+       transformation and confusion of ideas such an animal could
+       be credited with giving origin to a veritable goose; and the
+       investigation of the subject will also afford a singularly
+       apt illustration of the ready manner in which the fable of
+       one year or period becomes transmitted and transformed into
+       the secure and firm belief of the next.</p>
+
+    <p>We may begin our investigation by inquiring into some of the
+    opinions which were entertained on this subject and ventilated
+    by certain old writers. Between 1154 and 1189 Giraldus
+    Cambrensis, in a work entitled "Topographia Hiberniae," written
+    in Latin, remarks concerning "many birds which are called
+    Bernacae: against nature, nature produces them in a most
+    extraordinary way. They are like marsh geese, but somewhat
+    smaller. They are produced from fir timber tossed along the
+    sea, and are at first like gum. Afterward <span class=
+    "pagenum"><a name="page150"
+       id="page150"></a>[pg 150]</span> they hang down by their
+       beaks, as if from a sea-weed attached to the timber,
+       surrounded by shells, in order to grow more freely,"
+       Giraldus is here evidently describing the barnacles
+       themselves. He continues: "Having thus, in process of time,
+       been clothed with a strong coat of feathers, they either
+       fall into the water or fly freely away into the air. They
+       derive their food and growth from the sap of the wood or the
+       sea, by a secret and most wonderful process of alimentation.
+       I have frequently, with my own eyes, seen more than a
+       thousand of these small bodies of birds, hanging down on the
+       seashore from one piece of timber, enclosed in shells, and
+       already formed." Here, again, our author is speaking of the
+       barnacles themselves, with which he naturally confuses the
+       geese, since he presumes the Crustaceans are simply geese in
+       an undeveloped state. He further informs his readers that,
+       owing to their presumably marine origin, "bishops and
+       clergymen in some parts of Ireland do not scruple to dine
+       off these birds at the time of fasting, because they are not
+       flesh, nor born of flesh," although for certain other and
+       theological reasons, not specially requiring to be discussed
+       in the present instance, Giraldus disputes the legality of
+       this practice of the Hibernian clerics.</p>
+
+    <p>In the year 1527 appeared "The Hystory and Croniclis of
+    Scotland, with the cosmography and dyscription thairof,
+    compilit be the noble Clerk Maister Hector Boece, Channon of
+    Aberdene." Boece's "History" was written in Latin; the title we
+    have just quoted being that of the English version of the work
+    (1540), which title further sets forth that Boece's work was
+    "Translait laitly in our vulgar and commoun langage be
+    <span class="pagenum"><a name="page151"
+       id="page151"></a>[pg 151]</span> Maister Johne Bellenden,
+       Archedene of Murray, And Imprentit in Edinburgh, be me
+       Thomas Davidson, prenter to the Kyngis nobyll grace." In
+       this learned work the author discredits the popular ideas
+       regarding the origin of the geese. "Some men belevis that
+       thir clakis (geese) growis on treis be the nebbis (bills).
+       Bot thair opinoun is vane. And becaus the nature and
+       procreatioun of thir clakis is strange, we have maid na
+       lytyll laboure and deligence to serche ye treuth and verite
+       yairof, we have salit (sailed) throw ye seis quhare thir
+       clakis ar bred, and I fynd be gret experience, that the
+       nature of the seis is mair relevant caus of thair
+       procreatioun than ony uthir thyng." According to Boece,
+       then, "the nature of the seis" formed the chief element in
+       the production of the geese, and our author proceeds to
+       relate how "all treis (trees) that ar casein in the seis be
+       proces of tyme apperis first wormeetin (worm-eaten), and in
+       the small boris and hollis (holes) thairof growis small
+       worms." Our author no doubt here alludes to the ravages of
+       the Teredo, or ship-worm, which burrows into timber, and
+       with which the barnacles themselves are thus confused. Then
+       he continues, the "wormis" first "schaw (show) thair heid
+       and feit, and last of all thay schaw thair plumis and
+       wyngis. Finaly, quhen thay ar cumyn to the just mesure and
+       quantite of geis, thay fle in the aire as othir fowlis dois,
+       as was notably provyn, in the yeir of God ane thousand iii
+       hundred lxxxx, in sicht of mony pepyll, besyde the castell
+       of Petslego." On the occasion referred to, Boece tells us
+       that a great tree was cast on shore, and was divided, by
+       order of the "laird" of the ground, by means of a saw.
+       Wonderful to relate, the tree was found not <span class=
+       "pagenum"><a name="page152"
+       id="page152"></a>[pg 152]</span> merely to be riddled with a
+       "multitude of wormis," throwing themselves out of the holes
+       of the tree, but some of the "wormis" had "baith heid, feit,
+       and wyngis," but, adds the author, "they had no fedderis
+       (feathers)."</p>
+
+    <p>Unquestionably, either "the scientific use of the
+    imagination" had operated in this instance in inducing the
+    observers to believe that in this tree, riddled by the
+    ship-worms and possibly having barnacles attached to it, they
+    beheld young geese; or Boece had construed the appearances
+    described as those representing the embryo stages of the
+    barnacle geese.</p>
+
+    <p>Boece further relates how a ship named the Christofir was
+    brought to Leith, and was broken down because her timbers had
+    grown old and failing. In these timbers were beheld the same
+    "wormeetin" appearances, "all the hollis thairof" being "full
+    of geis." Boece again most emphatically rejects the idea that
+    the "geis" were produced from the wood of which the timbers
+    were composed, and once more proclaims his belief that the
+    "nature of the seis resolvit in geis" may be accepted as the
+    true and final explanation of their origin. A certain "Maister
+    Alexander Galloway" had apparently strolled with the historian
+    along the sea-coast, the former giving "his mynd with maist
+    ernist besynes to serche the verite of this obscure and mysty
+    dowtis." Lifting up a piece of tangle, they beheld the seaweed
+    to be hanging full of mussel-shells from the root to the
+    branches. Maister Galloway opened one of the mussel-shells, and
+    was "mair astonis than afore" to find no fish therein, but a
+    perfectly shaped "foule, smal and gret," as corresponded to the
+    "quantity of the <span class="pagenum"><a name="page153"
+       id="page153"></a>[pg 153]</span> shell." And once again
+       Boece draws the inference that the trees or wood on which
+       the creatures are found have nothing to do with the origin
+       of the birds; and that the fowls are begotten of the
+       "occeane see, quhilk," concludes our author, "is the caus
+       and production of mony wonderful thingis."</p>
+
+    <p>More than fifty years after the publication of Boece's
+    "History," old Gerard of London, the famous "master in
+    chirurgerie" of his day, gave an account of the barnacle goose,
+    and not only entered into minute particulars of its growth and
+    origin, but illustrated its manner of production by means of
+    the engraver's art of his day. Gerard's "Herball," published in
+    1597, thus contains, amongst much that is curious in medical
+    lore, a very quaint piece of zoölogical history. He tells us
+    that "in the north parts of Scotland, and the Hands adjacent,
+    called Orchades (Orkneys)," are found "certaine trees, whereon
+    doe growe certaine shell fishes, of a white colour tending to
+    russet; wherein are conteined little living creatures: which
+    shels in time of maturitie doe open, and out of them grow those
+    little living foules whom we call Barnakles, in the north of
+    England Brant Geese, and in Lancashire tree Geese; but the
+    other that do fall upon the land, perish, and come to nothing:
+    thus much by the writings of others, and also from the mouths
+    of people of those parts, which may," concludes Gerard, "very
+    well accord with truth."</p>
+
+    <p>Not content with hearsay evidence, however, Gerard relates
+    what his eyes saw and hands touched. He describes how on the
+    coasts of a certain "small Hand in Lancashire called Pile of
+    Foulders" (probably Peel <span class="pagenum"><a name=
+    "page154"
+       id="page154"></a>[pg 154]</span> Island), the wreckage of
+       ships is cast up by the waves, along with the trunks and
+       branches "of old and rotten trees." On these wooden
+       rejectamenta "a certaine spume or froth" grows, according to
+       Gerard. This spume "in time breedeth unto certaine shels, in
+       shape like those of the muskle, but sharper pointed, and of
+       a whitish color." This description, it may be remarked,
+       clearly applies to the barnacles themselves. Gerard then
+       continues to point out how, when the shell is perfectly
+       formed, it "gapeth open, and the first thing that appeereth
+       is the foresaid lace or string"&mdash;the substance
+       described by Gerard as contained within the
+       shell&mdash;"next come the legs of the Birde hanging out;
+       and as it groweth greater, it openeth the shell by degrees,
+       till at length it is all come forth, and hangeth only by the
+       bill; in short space after it commeth to full maturitie, and
+       falleth into the sea, where it gathereth feathers, and
+       groweth to a foule, bigger than a Mallard, and lesser than a
+       Goose, having blacke legs and bill or beake, and feathers
+       blacke and white ... which the people of Lancashire call by
+       no other name than a tree Goose."</p>
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/154.png"><img width="250"
+             src="images/154.png"
+             alt="FIG. 1. THE BARNACLE TREE." /></a><br />
+        FIG. 1. THE BARNACLE TREE.<br />
+        (From Gerard's "Herball.")
+    </div>
+
+    <p>Accompanying this description is the engraving of the
+    barnicle tree (Fig. 1) bearing its geese progeny. From the open
+    shells in two cases, the little geese are seen protruding,
+    whilst several of the fully-fledged fowls <span class=
+    "pagenum"><a name="page155"
+       id="page155"></a>[pg 155]</span> are disporting themselves
+       in the sea below. Gerard's concluding piece of information,
+       with its exordium, must not be omitted. "They spawne," says
+       the wise apothecary, "as it were, in March or Aprill; the
+       Geese are found in Maie or June, and come to fulnesse of
+       feathers in the moneth after. And thus hauing, through God's
+       assistance, discoursed somewhat at large of Grasses, Herbes,
+       Shrubs, Trees, Mosses, and certaine excrescences of the
+       earth, with other things moe incident to the Historic
+       thereof, we conclude and end our present volume, with this
+       woonder of England. For which God's name be euer honored and
+       praised." It is to be remarked that Gerard's description of
+       the goose-progeny of the barnacle tree exactly corresponds
+       with the appearance of the bird known to ornithologists as
+       the "barnacle-goose"; and there can be no doubt that,
+       skilled as was this author in the natural history lore of
+       his day, there was no other feeling in his mind than that of
+       firm belief in and pious wonder at the curious relations
+       between the shells and their fowl-offspring. Gerard thus
+       attributes the origin of the latter to the barnacles. He
+       says nothing of the "wormeetin" holes and burrows so
+       frequently mentioned by Boece, nor would he have agreed with
+       the latter in crediting the "nature of the occeane see" with
+       their production, save in so far as their barnacle-parents
+       lived and existed in the waters of the ocean.</p>
+
+    <p>The last account of this curious fable which we may allude
+    to in the present instance is that of Sir Robert Moray, who, in
+    his work entitled "A Relation concerning Barnacles," published
+    in the <i>Philosophical Transactions</i> of the Royal Society
+    in 1677-78, gives a <span class="pagenum"><a name="page156"
+       id="page156"></a>[pg 156]</span> succinct account of these
+       crustaceans and their bird-progeny. Sir Robert is described
+       as "lately one of his Majesties Council for the Kingdom of
+       Scotland," and we may therefore justly assume his account to
+       represent that of a cultured, observant person of his day
+       and generation. The account begins by remarking that the
+       "most ordinary trees" found in the western islands of
+       Scotland "are Firr and Ash." "Being," continues Sir Robert,
+       "in the Island of East (Uist), I saw lying upon the shore a
+       cut of a large Firr tree of about 2-1/2 foot diameter, and 9
+       or 10 foot long; which had lain so long out of the water
+       that it was very dry: And most of the shells that had
+       formerly cover'd it, were worn or rubb'd off. Only on the
+       parts that lay next the ground, there still hung multitudes
+       of little Shells; having within them little Birds, perfectly
+       shap'd, supposed to be Barnacles." Here again the
+       description applies to the barnacles; the "little birds"
+       they are described as containing being of course the bodies
+       of the shell-fish.</p>
+
+    <p>"The Shells," continues the narrator, "hang at the Tree by a
+    Neck longer than the Shell;" this "neck" being represented by
+    the stalk of the barnacle. The neck is described as being
+    composed "of a kind of filmy substance, round, and hollow, and
+    creased, not unlike the Wind-pipe of a Chicken; spreading out
+    broadest where it is fastened to the Tree, from which it seems
+    to draw and convey the matter which serves for the growth and
+    vegetation of the Shell and the little Bird within it." Sir
+    Robert Moray therefore agrees in respect of the manner of
+    nourishment of the barnacles with the opinion of Giraldus
+    already quoted. The <span class="pagenum"><a name="page157"
+       id="page157"></a>[pg 157]</span> author goes on to describe
+       the "Bird" found in every shell he opened; remarking that
+       "there appeared nothing wanting as to the internal parts,
+       for making up a perfect Sea-fowl: every little part
+       appearing so distinctly, that the whole looked like a large
+       Bird seen through a concave or diminishing Glass, colour and
+       feature being everywhere so clear and neat." The "Bird" is
+       most minutely described as to its bill, eyes, head, neck,
+       breast, wings, tail, and feet, the feathers being
+       "everywhere perfectly shaped, and blackish-coloured. All
+       being dead and dry," says Sir Robert, "I did not look after
+       the Internal parts of them," a statement decidedly
+       inconsistent with his previous assertion as to the perfect
+       condition of the "internal parts"; and he takes care to add,
+       "nor did I ever see any of the little Birds alive, nor met
+       with anybody that did. Only some credible persons," he
+       concludes, "have assured me they have seen some as big as
+       their fist."</p>
+
+    <div class="figright"
+         style="width:400px;">
+        <a href="images/157.png"><img width="400"
+             src="images/157.png"
+             alt="FIG. 2. BARNACLE TREE." /></a><br />
+        FIG. 2. BARNACLE TREE.<br />
+        (From Munster's "Cosmography.")
+    </div>
+
+    <p>This last writer thus avers that he saw little birds within
+    the shells he clearly enough describes as those of the
+    barnacles. We must either credit Sir Robert <span class=
+    "pagenum"><a name="page158"
+       id="page158"></a>[pg 158]</span> with describing what he
+       never saw, or with misconstruing what he did see. His
+       description of the goose corresponds with that of the
+       barnacle goose, the reputed progeny of the shells; and it
+       would, therefore, seem that this author, with the myth at
+       hand, saw the barnacles only with the eyes of a credulous
+       observer, and thus beheld, in the inside of each
+       shell&mdash;if, indeed, his research actually extended thus
+       far&mdash;the reproduction in miniature of a goose, with
+       which, as a mature bird, he was well acquainted.</p>
+
+    <p>On p. 157 is a woodcut, copied from Munster's "Cosmography"
+    (1550), a very popular book in its time, showing the tree with
+    its fruit, and the geese which are supposed to have just
+    escaped from it.</p>
+
+    <p>This historical ramble may fitly preface what we have to say
+    regarding the probable origin of the myth. By what means could
+    the barnacles become credited with the power of producing the
+    well-known geese? Once started, the progress and growth of the
+    myth are easily accounted for. The mere transmission of a fable
+    from one generation or century to another is a simply explained
+    circumstance, and one exemplified by the practices of our own
+    times. The process of accretion and addition is also well
+    illustrated in the perpetuation of fables; since the tale is
+    certain to lose nothing in its historical journey, but, on the
+    contrary, to receive additional elaboration with increasing
+    age. Professor Max Müller, after discussing various theories of
+    the origin of the barnacle myth, declares in favor of the idea
+    that confusion of language and alteration of names lie at the
+    root of the error. The learned author of the "Science of
+    Language" argues that the true barnacles <span class=
+    "pagenum"><a name="page159"
+       id="page159"></a>[pg 159]</span> were named, properly
+       enough, Bernaculae, and lays stress on the fact that
+       Bernicle geese were first caught in Ireland. That country
+       becomes <i>Hibernia</i> in Latin, and the Irish geese were
+       accordingly named Hibernicae, or Hiberniculae. By the
+       omission of the first syllable&mdash;no uncommon operation
+       for words to undergo&mdash;we obtain the name Berniculae for
+       the geese, this term being almost synonymous with the name
+       Bernaculae already applied, as we have seen, to the
+       barnacles. Bernicle geese and bernicle shells, confused in
+       name, thus became confused in nature; and, once started, the
+       ordinary process of growth was sufficient to further
+       intensify, and render more realistic, the story of the
+       bernicle tree and its wonderful progeny.</p>
+
+    <p>By way of a companion legend to that of the barnacle tree,
+    we may select the story of the "Lamb Tree" of Cathay, told by
+    Sir John Mandeville, whose notes of travel regarding
+    crocodiles' tears, and other points in the conformation of
+    these reptiles, have already been referred to. Sir John, in
+    that chapter of his work which treats "Of the Contries and Yles
+    that ben bezonde the Lond of Cathay; and of the Frutes there,"
+    etc., relates that in Cathay "there growethe a manner of Fruyt,
+    as thoughe it were Gowrdes: and whan thei ben rype, men kutten
+    (cut) hem a to (them in two), and men fyndem with inne a
+    lytylle Best (beast), in Flessche in Bon and Blode (bone and
+    blood) as though it were a lytylle Lomb (lamb) with outen wolle
+    (without wool). And men eaten both the Frut and the Best; and
+    that," says Sir John, "is a great marveylle. Of that frut," he
+    continues, "I have eten; alle thoughe it were
+    wondirfulle"&mdash;this being added, no doubt, from an idea
+    <span class="pagenum"><a name="page160"
+       id="page160"></a>[pg 160]</span> that there might possibly
+       be some stay-at-home persons who would take Sir John's
+       statement <i>cum grano salis</i>. "But," adds this worthy
+       "knyght of Ingolond," "I knowe wel that God is marveyllous
+       in His Werkes." Not to be behind the inhabitants of Cathay
+       in a tale of wonders, the knight related to these Easterns
+       "als gret a marveylle to hem that is amonges us; and that
+       was of the Bernakes. For I tolde him hat in oure Countree
+       weren Trees that beren a Fruyt, that becomen Briddes (birds)
+       fleeynge: and tho that fellen in the Water lyven (live); and
+       thei that fallen on the Erthe dyen anon: and thei ben right
+       gode to mannes mete (man's meat). And here had thei als gret
+       marvayle," concludes Sir John, "that sume of hem trowed it
+       were an impossible thing to be." Probably the inhabitants of
+       Cathay, knowing their own weakness as regards the lamb tree,
+       might possess a fellow-feeling for their visitor's
+       credulity, knowing well, from experience, the readiness with
+       which a "gret marvayle" could be evolved and sustained.</p>
+
+    <p>Passing from the sphere of the mythical and marvellous as
+    represented in mediaeval times, we may shortly discuss a
+    question, which, of all others, may justly claim a place in the
+    records of Zoölogical curiosities&mdash;namely, the famous and
+    oft-repeated story of the "Toad from the solid rock," as the
+    country newspapers style the incident. Regularly, year by year,
+    and in company with the reports of the sea-serpent's
+    reappearance, we may read of the discoveries of toads and frogs
+    in situations and under circumstances suggestive of a singular
+    vitality on the part of the amphibians, of more than usual
+    credulity on the part of the hearers, <span class=
+    "pagenum"><a name="page161"
+       id="page161"></a>[pg 161]</span> or of a large share of
+       inventive genius in the narrators of such tales. The
+       question possesses for every one a certain degree of
+       interest, evoked by the curious and strange features
+       presented on the face of the tales. And it may therefore not
+       only prove an interesting but also a useful study, if we
+       endeavor to arrive at some just and logical conceptions of
+       these wonderful narrations.</p>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/161.png"><img width="600"
+             src="images/161.png"
+             alt="Discovering toad." /></a>
+    </div>
+
+    <p>Instances of the discovery of toads and frogs in solid rocks
+    need not be specially given; suffice it to say, that these
+    narratives are repeated year by year with little variation. A
+    large block of stone or face of rock is detached from its site,
+    and a toad or frog is seen hereafter to be hopping about in its
+    usual lively manner. The conclusion to which the bystanders
+    invariably come is that the animal must have been contained
+    within the rock, and that it was liberated by the dislodgement
+    of the mass. Now, in many instances, cases of the appearance of
+    toads during quarrying <span class="pagenum"><a name="page162"
+       id="page162"></a>[pg 162]</span> operations have been found,
+       on close examination, to present no evidence whatever that
+       the appearance of the animals was due to the dislodgement of
+       the stones. A frog or toad may be found hopping about among
+       some recently formed débris, and the animal is at once
+       seized upon and reported as having emerged from the rocks
+       into the light of day. There is in such a case not the
+       slightest ground for supposing any such thing; and the
+       animal may more reasonably be presumed to have simply hopped
+       into the débris from its ordinary habitat. But laying aside
+       narratives of this kind, which lose their plausibility under
+       a very commonplace scrutiny, there still exist cases,
+       reported in an apparently exact and truthful manner, in
+       which these animals have been alleged to appear from the
+       inner crevices of rocks after the removal of large masses of
+       the formations. We shall assume these latter tales to
+       contain a plain, unvarnished statement of what was observed,
+       and deal with the evidence they present on this footing.</p>
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/162.png"><img width="250"
+             src="images/162.png"
+             alt="A TOAD." /></a><br />
+        A TOAD.
+    </div>
+
+    <p>One or two notable examples of such verified tales are
+    related by Smellie, in his "Philosophy of Natural History."
+    Thus, in the "Memoirs of the French Academy of Sciences" for
+    1719, a toad is described as having been found in the heart of
+    an elm tree; and another is stated to have been found in the
+    heart of an old oak tree, in 1731, near Nantz. The condition
+    <span class="pagenum"><a name="page163"
+       id="page163"></a>[pg 163]</span> of the trees is not
+       expressly stated, nor are we afforded any information
+       regarding the appearance of the toads&mdash;particulars of
+       considerable importance in view of the suggestions and
+       explanations to be presently brought forward. Smellie
+       himself, while inclined to be sceptical in regard to the
+       truth or exactness of many of the tales told of the vitality
+       of toads, regards the matter as affording food for
+       reflection, since he remarks, "But I mean not to persuade,
+       for I cannot satisfy myself; all I intend is, to recommend
+       to those gentlemen who may hereafter chance to see such rare
+       phenomena, a strict examination of every circumstance that
+       can throw light upon a subject so dark and mysterious; for
+       the vulgar, ever inclined to render uncommon appearances
+       still more marvellous, are not to be trusted."</p>
+
+    <p>This author strikes the key-note of the inquiry in his
+    concluding words, and we shall find that the explanation of the
+    matter really lies in the clear understanding of what are the
+    probabilities, and what the actual details, of the cases
+    presented for consideration. We may firstly, then, glance at a
+    few of the peculiarities of the frogs and toads, regarded from
+    a zoölogical point of view. As every one knows, these animals
+    emerge from the egg in the form of little fish-like "tadpoles,"
+    provided with outside gills, which are soon replaced by inside
+    gills, resembling those of fishes. The hind legs are next
+    developed, and the fore limbs follow a little later; whilst,
+    with the development of lungs, and the disappearance of the
+    gills and tail, the animal leaves the water, and remains for
+    the rest of its life an air-breathing, terrestrial animal.
+    Then, <span class="pagenum"><a name="page164"
+       id="page164"></a>[pg 164]</span> secondly, in the adult frog
+       or toad, the naturalist would point to the importance of the
+       skin as not only supplementing, but, in some cases, actually
+       supplanting the work of the lungs as the breathing organ.
+       Frogs and toads will live for months under water, and will
+       survive the excision of the lungs for like periods; the skin
+       in such cases serving as the breathing surface. A third
+       point worthy of remembrance is included in the facts just
+       related, and is implied in the information that these
+       animals can exist for long periods without food, and with
+       but a limited supply of air. We can understand this
+       toleration on the part of these animals when we take into
+       consideration their cold-blooded habits, which do not
+       necessitate, and which are not accompanied by, the amount of
+       vital activity we are accustomed to note in higher animals.
+       And, as a last feature in the purely scientific history of
+       the frogs and toads, it may be remarked that these animals
+       are known to live for long periods. One pet toad is
+       mentioned by a Mr. Arscott as having attained, to his
+       knowledge, the age of thirty-six years; and a greater age
+       still might have been recorded of this specimen, but for the
+       untoward treatment it sustained at the hands, or rather
+       beak, of a tame raven. In all probability it may be safely
+       assumed that, when the conditions of life are favorable,
+       these creatures may attain a highly venerable
+       age&mdash;regarding the lapse of time from a purely human
+       and interested point of view.</p>
+
+    <p>We may now inquire whether or not the foregoing
+    considerations may serve to throw any light upon the tales of
+    the quarryman. The first point to which attention may be
+    directed is that involved in the statement <span class=
+    "pagenum"><a name="page165"
+       id="page165"></a>[pg 165]</span> that the amphibian has been
+       imprisoned in a <i>solid</i> rock. Much stress is usually
+       laid on the fact that the rock was solid; this fact being
+       held to imply the great age, not to say antiquity, of the
+       rock and its supposed tenant. The impartial observer, after
+       an examination of the evidence presented, will be inclined
+       to doubt greatly the justification for inserting the
+       adjective "solid"; for usually no evidence whatever is
+       forthcoming as to the state of the rock prior to its
+       removal. No previous examination of the rock is or can be
+       made, from the circumstance that no interest can possibly
+       attach to its condition until its removal reveals the
+       apparent wonder it contained, in the shape of the live toad.
+       And it is equally important to note that we rarely, if ever,
+       find mention of any examination of the rock being made
+       subsequently to the discovery. Hence, a first and grave
+       objection may be taken to the validity of the supposition
+       that the rock was solid, and it may be fairly urged that on
+       this supposition the whole question turns and depends. For
+       if the rock cannot be proved to have been impermeable to and
+       barred against the entrance of living creatures, the
+       objector may proceed to show the possibility of the toad
+       having gained admission, under certain notable
+       circumstances, to its prison-house.</p>
+
+    <p>The frog or toad in its young state, and having just entered
+    upon its terrestrial life, is a small creature, which could,
+    with the utmost ease, wriggle into crevices and crannies of a
+    size which would almost preclude such apertures being noticed
+    at all. Gaining access to a roomier crevice or nook within, and
+    finding there a due supply of air, along with a dietary
+    consisting chiefly <span class="pagenum"><a name="page166"
+       id="page166"></a>[pg 166]</span> of insects, the animal
+       would grow with tolerable rapidity, and would increase to
+       such an extent that egress through its aperture of entrance
+       would become an impossibility. Next, let us suppose that the
+       toleration of the toad's system to starvation and to a
+       limited supply of air is taken into account, together with
+       the fact that these creatures will hibernate during each
+       winter, and thus economize, as it were, their vital activity
+       and strength; and after the animal has thus existed for a
+       year or two&mdash;no doubt under singularly hard
+       conditions&mdash;let us imagine that the rock is split up by
+       the wedge and lever of the excavator. We can then readily
+       enough account for the apparently inexplicable story of "the
+       toad in the rock." "There is the toad and here is the solid
+       rock," say the gossips. "There is an animal which has
+       singular powers of sustaining life under untoward
+       conditions, and which, in its young state, could have gained
+       admittance to the rock through a mere crevice," says the
+       naturalist in reply. Doubtless, the great army of the
+       unconvinced may still believe in the tale as told them; for
+       the weighing of evidence and the placing <i>pros</i> and
+       <i>cons</i> in fair contrast are not tasks of congenial or
+       wonted kind in the ordinary run of life. Some people there
+       will be who will believe in the original solid rock and its
+       toad, despite the assertion of the geologists that the
+       earliest fossils of toads appear in almost the last-formed
+       rocks, and that a live toad in rocks of very ancient
+       age&mdash;presuming, according to the popular belief, that
+       the animal was enclosed when the rock was formed&mdash;would
+       be as great an anomaly and wonder as the mention, as an
+       historical fact, of an express train or the telegraph in the
+       days of the patriarchs. <span class="pagenum"><a name=
+       "page167"
+       id="page167"></a>[pg 167]</span> In other words, the live
+       toad which hops out of an Old Red Sandstone rock must be
+       presumed, on the popular belief, to be older by untold ages
+       than the oldest fossil frogs and toads. The reasonable mind,
+       however, will ponder and consider each feature of the case,
+       and will rather prefer to countenance a supposition based on
+       ordinary experience, than an explanation brought ready-made
+       from the domain of the miraculous; whilst not the least
+       noteworthy feature of these cases is that included in the
+       remark of Smellie, respecting the tendency of uneducated and
+       superstitious persons to magnify what is uncommon, and in
+       his sage conclusion that as a rule such persons in the
+       matter of their relations "are not to be trusted."</p>
+
+    <p>But it must also be noted that we possess valuable evidence
+    of a positive and direct kind bearing on the duration of life
+    in toads under adverse circumstances. As this evidence tells
+    most powerfully against the supposition that the existence of
+    those creatures can be indefinitely prolonged, it forms of
+    itself a veritable court of appeal in the cases under
+    discussion. The late Dr. Buckland, curious to learn the exact
+    extent of the vitality of the toad, caused, in the year 1825,
+    two large blocks of stone to be prepared. One of the blocks was
+    taken from the oölite limestone, and in this first stone twelve
+    cells were excavated. Each cell was one foot deep and five
+    inches in diameter. The mouth of each cell was grooved so as to
+    admit of two covers being placed over the aperture; the first
+    or lower cover being of glass, and the upper one of slate. Both
+    covers were so adapted that they could be firmly luted down
+    with clay or putty; the object of this double protection
+    <span class="pagenum"><a name="page168"
+       id="page168"></a>[pg 168]</span> being that the slate cover
+       could be raised so as to inspect the contained object
+       through the closed glass cover without admitting air. In the
+       second or sandstone block, a series of twelve cells was also
+       excavated; these latter cells being, however, of smaller
+       size than those of the limestone block, each cell being only
+       six inches in depth by five inches in diameter. These cells
+       were likewise fitted with double covers.</p>
+
+    <p>On November 26th, 1825, a live toad&mdash;kept for some time
+    previously to insure its being healthy&mdash;was placed in each
+    of the twenty-four cells. The largest specimen weighed 1185
+    grains, and the smallest 115 grains. The stones and the immured
+    toads were buried on the day mentioned, three feet deep, in Dr.
+    Buckland's garden. There they lay until December 10th, 1826,
+    when they were disinterred and their tenants examined. All the
+    toads in the smaller cells of the sandstone block were dead,
+    and from the progress of decomposition it was inferred that
+    they had succumbed long before the date of disinterment. The
+    majority of the toads in the limestone block were alive, and,
+    curiously enough, one or two had actually increased in weight.
+    Thus, No. 5, which at the commencement of its captivity had
+    weighed 1185 grains, had increased to 1265 grains; but the
+    glass cover of No. 5's cell was found to be cracked. Insects
+    and air must therefore have obtained admittance and have
+    afforded nourishment to the imprisoned toad; this supposition
+    being rendered the more likely by the discovery that in one of
+    the cells, the covers of which were also cracked and the tenant
+    of which was dead, numerous insects were found. No. 9, weighing
+    originally 988 grains, had <span class="pagenum"><a name=
+    "page169"
+       id="page169"></a>[pg 169]</span> increased during its
+       incarceration to 1116 grains; but No. 1, which in the year
+       1825 had weighed 924 grains, was found in December, 1826, to
+       have decreased to 698 grains; and No. 11, originally
+       weighing 936 grains, had likewise disagreed with the
+       imprisonment, weighing only 652 grains when examined in
+       1826.</p>
+
+    <p>At the period when the blocks of stone were thus prepared,
+    four toads were pinned up in holes five inches deep and three
+    inches in diameter, cut in the, stem of an apple-tree; the
+    holes being firmly plugged with tightly fitting wooden plugs.
+    These four toads were found to be dead when examined along with
+    the others in 1826; and of four others enclosed in basins made
+    of plaster of Paris, and which were also buried in Dr.
+    Buckland's garden, two were found to be dead at the end of a
+    year, their comrades being alive, but looking starved and
+    meagre. The toads which were found alive in the limestone block
+    in December, 1826, were again immured and buried, but were
+    found to be dead, without leaving a single survivor, at the end
+    of the second year of their imprisonment.</p>
+
+    <p>These experiments may fairly be said to prove two points.
+    They firstly show that under circumstances even of a favorable
+    kind when compared with the condition popularly believed
+    in&mdash;namely, that of being enclosed in a <i>solid</i>
+    rock&mdash;the limit of the toad's life may be assumed to be
+    within two years; this period being no doubt capable of being
+    extended when the animal gains a slight advantage, exemplified
+    by the admission of air and insect-food. Secondly, we may
+    reasonably argue that these experiments show that toads when
+    rigorously treated, like other animals, <span class=
+    "pagenum"><a name="page170"
+       id="page170"></a>[pg 170]</span> become starved and meagre,
+       and by no means resemble the lively, well-fed animals
+       reported as having emerged from an imprisonment extending,
+       in popular estimation, through periods of inconceivable
+       duration.</p>
+
+    <p>These tales are, in short, as devoid of actual foundation as
+    are the modern beliefs in the venomous properties of the toad,
+    or the ancient beliefs in the occult and mystic powers of
+    various parts of its frame when used in incantations.
+    Shakespeare, whilst attributing to the toad venomous qualities,
+    has yet immortalized it in his famous simile by crediting it
+    with the possession of a "precious jewel." But even in the
+    latter case the animal gets but scant justice; for science
+    strips it of its poetical reputation, and in this, as in other
+    respects, shows it, despite fable and myth, to be zoölogically
+    an interesting, but otherwise a commonplace member of the
+    animal series.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/170.png"><img width="500"
+             src="images/170.png"
+             alt="Toads." /></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="page171"
+       id="page171"></a>[pg 171]</span>
+
+    <h2>ON A PIECE OF CHALK</h2>
+
+    <h3><i>A LECTURE TO WORKING MEN</i>.</h3>
+
+    <h4>(Delivered in England.)</h4>
+
+    <h3><span class="sc">By</span> T.H. HUXLEY.</h3>
+    <hr class="short" />
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/171.png"><img width="300"
+             src="images/171.png"
+             alt="A CHALK CLIFF." /></a><br />
+        A CHALK CLIFF.
+    </div>
+
+    <p>If a well were to be sunk at our feet in the midst of the
+    city of Norwich, the diggers would very soon find themselves at
+    work in that white substance almost too soft to be called rock,
+    with which we are all familiar as "chalk."</p>
+
+    <p>Not only here, but over the whole county of Norfolk, the
+    well-sinker might carry his shaft down many hundred feet
+    without coming to the end of the chalk; and, on the sea-coast,
+    where the waves have pared away the face of the land which
+    breasts them, the scarped faces of the high cliffs are often
+    wholly formed of the same material. Northward, the chalk may be
+    followed as far as Yorkshire; on the <span class=
+    "pagenum"><a name="page172"
+       id="page172"></a>[pg 172]</span> south coast it appears
+       abruptly in the picturesque western bays of Dorset, and
+       breaks into the Needles of the Isle of Wight; while on the
+       shores of Kent it supplies that long line of white cliffs to
+       which England owes her name of Albion.</p>
+
+    <p>Were the thin soil which covers it all washed away, a curved
+    band of white chalk, here broader, and there narrower, might be
+    followed diagonally across England from Lulworth in Dorset, to
+    Flamborough Head in Yorkshire&mdash;a distance of over two
+    hundred and eighty miles as the crow flies.</p>
+
+    <p>From this band to the North Sea, on the east, and the
+    Channel, on the south, the chalk is largely hidden by other
+    deposits; but, except in the Weald of Kent and Sussex, it
+    enters into the very foundation of all the south-eastern
+    counties.</p>
+
+    <p>Attaining, as it does in some places, a thickness of more
+    than a thousand feet, the English chalk must be admitted to be
+    a mass of considerable magnitude. Nevertheless, it covers but
+    an insignificant portion of the whole area occupied by the
+    chalk formation of the globe, which has precisely the same
+    general character as ours, and is found in detached patches,
+    some less, and others more extensive, than the English.</p>
+
+    <p>Chalk occurs in north-west Ireland; it stretches over a
+    large part of France&mdash;the chalk which underlies Paris
+    being, in fact, a continuation of that of the London basin; it
+    runs through Denmark and Central Europe, and extends southward
+    to North Africa; while eastward, it appears in the Crimea and
+    in Syria, and may be traced as far as the shores of the Sea of
+    Aral, in Central Asia.</p><span class="pagenum"><a name=
+    "page173"
+       id="page173"></a>[pg 173]</span>
+
+    <p>If all the points at which true chalk occurs were
+    circumscribed, they would lie within an irregular oval about
+    three thousand miles in long diameter&mdash;the area of which
+    would be as great as that of Europe, and would many times
+    exceed that of the largest existing inland sea&mdash;the
+    Mediterranean.</p>
+
+    <p>Thus the chalk is no unimportant element in the masonry of
+    the earth's crust, and it impresses a peculiar stamp, varying
+    with the conditions to which it is exposed, on the scenery of
+    the districts in which it occurs. The undulating downs and
+    rounded coombs, covered with sweet-grassed turf, of our inland
+    chalk country, have a peacefully domestic and mutton-suggesting
+    prettiness, but can hardly be called either grand or beautiful.
+    But on our southern coasts, the wall-sided cliffs, many hundred
+    feet high, with vast needles and pinnacles standing out in the
+    sea, sharp and solitary enough to serve as perches for the wary
+    cormorant, confer a wonderful beauty and grandeur upon the
+    chalk headlands. And in the East, chalk has its share in the
+    formation of some of the most venerable of mountain ranges,
+    such as the Lebanon.</p>
+    <hr />
+
+    <p>What is this wide-spread component of the surface of the
+    earth? and whence did it come?</p>
+
+    <p>You may think this no very hopeful inquiry. You may not
+    unnaturally suppose that the attempt to solve such problems as
+    these can lead to no result, save that of entangling the
+    inquirer in vague speculations, incapable of refutation and of
+    verification.</p>
+
+    <p>If such were really the case, I should have selected some
+    other subject than a "piece of chalk" for my <span class=
+    "pagenum"><a name="page174"
+       id="page174"></a>[pg 174]</span> discourse. But, in truth,
+       after much deliberation, I have been unable to think of any
+       topic which would so well enable me to lead you to see how
+       solid is the foundation upon which some of the most
+       startling conclusions of physical science rest.</p>
+
+    <p>A great chapter of the history of the world is written in
+    the chalk. Few passages in the history of man can be supported
+    by such an overwhelming mass of direct and indirect evidence as
+    that which testifies to the truth of the fragment of the
+    history of the globe, which I hope to enable you to read, with
+    your own eyes, to-night.</p>
+
+    <div class="figleft"
+         style="width:400px;">
+        <a href="images/174.png"><img width="400"
+             src="images/174.png"
+             alt="MICROSCOPIC SECTION OF CHALK." /></a><br />
+        MICROSCOPIC SECTION OF CHALK.<br />
+        (Magnified nearly 300 times.)<br />
+        1. Textularia. 2. Globigerina. 3. Rotalia. 4. Coccoliths.
+    </div>
+
+    <p>Let me add, that few chapters of human history have a more
+    profound significance for ourselves. I weigh my words well when
+    I assert, that the man who should know the true history of the
+    bit of chalk which every carpenter carries about in his
+    breeches' pocket, though ignorant of all other history, is
+    likely, if he will think his knowledge out to its ultimate
+    results, to have a truer, and therefore a better, conception of
+    this wonderful universe, and of man's relation to it, than the
+    most learned student who <span class="pagenum"><a name=
+    "page175"
+       id="page175"></a>[pg 175]</span> is deep-read in the records
+       of humanity and ignorant of those of nature.</p>
+
+    <p>The language of the chalk is not hard to learn, not nearly
+    so hard as Latin, if you only want to get at the broad features
+    of the story it has to tell; and I propose that we now set to
+    work to spell that story out together.</p>
+
+    <p>We all know that if we "burn" chalk, the result is
+    quicklime. Chalk, in fact, is a compound of carbonic acid gas
+    and lime; and when you make it very hot, the carbonic acid
+    flies away and the lime is left.</p>
+
+    <p>By this method of procedure we see the lime, but we do not
+    see the carbonic acid. If, on the other hand, you were to
+    powder a little chalk and drop it into a good deal of strong
+    vinegar, there would be a great bubbling and fizzing, and,
+    finally, a clear liquid, in which no sign of chalk would
+    appear. Here you see the carbonic acid in the bubbles; the
+    lime, dissolved in the vinegar, vanishes from sight. There are
+    a great many other ways of showing that chalk is essentially
+    nothing but carbonic acid and quicklime. Chemists enunciate the
+    result of all the experiments which prove this, by stating that
+    chalk is almost wholly composed of "carbonate of lime."</p>
+
+    <p>It is desirable for us to start from the knowledge of this
+    fact, though it may not seem to help us very far toward what we
+    seek. For carbonate of lime is a widely-spread substance, and
+    is met with under very various conditions. All sorts of
+    limestones are composed of more or less pure carbonate of lime.
+    The crust which is often deposited by waters which have drained
+    through limestone rocks, in the form of what are called
+    stalagmites and stalactites, is carbonate of <span class=
+    "pagenum"><a name="page176"
+       id="page176"></a>[pg 176]</span> lime. Or, to take a more
+       familiar example, the fur on the inside of a tea-kettle is
+       carbonate of lime; and, for anything chemistry tells us to
+       the contrary, the chalk might be a kind of gigantic fur upon
+       the bottom of the earth-kettle, which is kept pretty hot
+       below.</p>
+
+    <p>Let us try another method of making the chalk tell us its
+    own history. To the unassisted eye chalk looks simply like a
+    very loose and open kind of stone. But it is possible to grind
+    a slice of chalk down so thin that you can see through
+    it&mdash;until it is thin enough, in fact, to be examined with
+    any magnifying power that may be thought desirable. A thin
+    slice of the fur of a kettle might be made in the same way. If
+    it were examined microscopically, it would show itself to be a
+    more or less distinctly laminated mineral substance, and
+    nothing more.</p>
+
+    <p>But the slice of chalk presents a totally different
+    appearance when placed under the microscope. The general mass
+    of it is made up of very minute granules; but, imbedded in this
+    matrix, are innumerable bodies, some smaller and some larger,
+    but, on a rough average, not more than a hundredth of an inch
+    in diameter, having a well-defined shape and structure. A cubic
+    inch of some specimens of chalk may contain hundreds of
+    thousands of these bodies, compacted together with incalculable
+    millions of the granules.</p>
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/176.png"><img width="250"
+             src="images/176.png"
+             alt="CHALK." /></a><br />
+        CHALK.<br />
+        (Magnified nearly 100 diameters.)
+    </div>
+
+    <p>The examination of a transparent slice gives a good notion
+    of the manner in which the components of the <span class=
+    "pagenum"><a name="page177"
+       id="page177"></a>[pg 177]</span> chalk are arranged, and of
+       their relative proportions. But, by rubbing up some chalk
+       with a brush in water and then pouring off the milky fluid,
+       so as to obtain sediments of different degrees of fineness,
+       the granules and the minute rounded bodies may be pretty
+       well separated from one another, and submitted to
+       microscopic examination, either as opaque or as transparent
+       objects. By combining the views obtained in these various
+       methods, each of the rounded bodies may be proved to be a
+       beautifully-constructed calcareous fabric, made up of a
+       number of chambers, communicating freely with one another.
+       The chambered bodies are of various forms. One of the
+       commonest is something like a badly-grown raspberry, being
+       formed of a number of nearly globular chambers of different
+       sizes congregated together. It is called Globigerina, and
+       some specimens of chalk consist of little else than
+       Globigerinæ and granules.</p>
+
+    <div class="figright"
+         style="width:150px;">
+        <a href="images/177.png"><img width="150"
+             src="images/177.png"
+             alt="GLOBIGERINA." /></a><br />
+        GLOBIGERINA.
+    </div>
+
+    <p>Let us fix our attention upon the Globigerina. It is the
+    spoor of the game we are tracking. If we can learn what it is
+    and what are the conditions of its existence, we shall see our
+    way to the origin and past history of the chalk.</p>
+
+    <p>A suggestion which may naturally enough present itself is,
+    that these curious bodies are the result of some process of
+    aggregation which has taken place in the carbonate of lime;
+    that, just as in winter, the rime on our windows simulates the
+    most delicate and elegantly arborescent foliage&mdash;proving
+    that the mere mineral matter may, under certain conditions,
+    assume the outward form of organic bodies&mdash;so this mineral
+    <span class="pagenum"><a name="page178"
+       id="page178"></a>[pg 178]</span> substance, carbonate of
+       lime, hidden away in the bowels of the earth, has taken the
+       shape of these chambered bodies. I am not raising a merely
+       fanciful and unreal objection. Very learned men, in former
+       days, have even entertained the notion that all the formed
+       things found in rocks are of this nature; and if no such
+       conception is at present held to be admissible, it is
+       because long and varied experience has now shown that
+       mineral matter never does assume the form and structure we
+       find in fossils. If anyone were to try to persuade you that
+       an oyster-shell (which is also chiefly composed of carbonate
+       of lime) had crystallized out of sea-water, I suppose you
+       would laugh at the absurdity. Your laughter would be
+       justified by the fact that all experience tends to show that
+       oyster-shells are formed by the agency of oysters, and in no
+       other way. And if there were no better reasons, we should be
+       justified, on like grounds, in believing that Globigerina is
+       not the product of anything but vital activity.</p>
+
+    <p>Happily, however, better evidence in proof of the organic
+    nature of the Globigerinæ than that of analogy is forthcoming.
+    It so happens that calcareous skeletons, exactly similar to the
+    Globigerinæ of the chalk, are being formed, at the present
+    moment, by minute living creatures, which flourish in
+    multitudes, literally more numerous than the sands of the
+    sea-shore, over a large extent of that part of the earth's
+    surface which is covered by the ocean.</p>
+
+    <p>The history of the discovery of these living Globigerinæ,
+    and of the part which they play in rock-building, is singular
+    enough. It is a discovery which, like others of no less
+    scientific importance, has arisen, <span class=
+    "pagenum"><a name="page179"
+       id="page179"></a>[pg 179]</span> incidentally, out of work
+       devoted to very different and exceedingly practical
+       interests.</p>
+
+    <p>When men first took to the sea, they speedily learned to
+    look out for shoals and rocks; and the more the burthen of
+    their ships increased, the more imperatively necessary it
+    became for sailors to ascertain with precision the depth of the
+    waters they traversed. Out of this necessity grew the use of
+    the lead and sounding-line; and, ultimately, marine-surveying,
+    which is the recording of the form of coasts and of the depth
+    of the sea, as ascertained by the sounding-lead, upon
+    charts.</p>
+
+    <p>At the same time, it became desirable to ascertain and to
+    indicate the nature of the sea-bottom, since this circumstance
+    greatly affects its goodness as holding ground for anchors.
+    Some ingenious tar, whose name deserves a better fate than the
+    oblivion into which it has fallen, attained this object by
+    "arming" the bottom of the lead with a lump of grease, to which
+    more or less of the sand or mud, or broken shells, as the case
+    might be, adhered, and was brought to the surface. But, however
+    well adapted such an apparatus might be for rough nautical
+    purposes, scientific accuracy could not be expected from the
+    armed lead, and to remedy its defects (especially when applied
+    to sounding in great depths) Lieutenant Brooke, of the American
+    Navy, some years ago invented a most ingenious machine, by
+    which a considerable portion of the superficial layer of the
+    sea-bottom can be scooped out and brought up, from any depth to
+    which the lead descends.</p>
+
+    <p>In 1853, Lieutenant Brooke obtained mud from the bottom of
+    the North Atlantic, between Newfoundland and the Azores, at a
+    depth of more than ten thousand <span class=
+       "pagenum"><a name="page180"
+       id="page180"></a>[pg 180]</span> feet, or two miles, by the
+       help of this sounding apparatus. The specimens were sent for
+       examination to Ehrenberg of Berlin, and to Bailey of West
+       Point, and those able microscopists found that this deep-sea
+       mud was almost entirely composed of the skeletons of living
+       organisms&mdash;the greater proportion of these being just
+       like the Globigerinæ already known to occur in chalk.</p>
+
+    <p>Thus far, the work had been carried on simply in the
+    interests of science, but Lieutenant Brooke's method of
+    sounding acquired a high commercial value, when the enterprise
+    of laying down the telegraph-cable between this country and the
+    United States was undertaken. For it became a matter of immense
+    importance to know, not only the depth of the sea over the
+    whole line, along which the cable was to be laid, but the exact
+    nature of the bottom, so as to guard against chances of cutting
+    or fraying the strands of that costly rope. The Admiralty
+    consequently ordered Captain Dayman, an old friend and shipmate
+    of mine, to ascertain the depth over the whole line of the
+    cable, and to bring back specimens of the bottom. In former
+    days, such a command as this might have sounded very much like
+    one of the impossible things which the young prince in the
+    Fairy Tales is ordered to do before he can obtain the hand of
+    the princess. However, in the months of June and July, 1857, my
+    friend performed the task assigned to him with great expedition
+    and precision, without, so far as I know, having met with any
+    reward of that kind. The specimens of Atlantic mud which he
+    procured were sent to me to be examined and reported upon.</p>
+
+    <p>The result of all these operations is, that we know
+    <span class="pagenum"><a name="page181"
+       id="page181"></a>[pg 181]</span> the contours and the nature
+       of the surface-soil covered by the North Atlantic, for a
+       distance of seventeen hundred miles from east to west, as
+       well as we know that of any part of the dry land.</p>
+
+    <p>It is a prodigious plain&mdash;one of the widest and most
+    even plains in the world. If the sea were drained off, you
+    might drive a wagon all the way from Valentia, on the west
+    coast of Ireland, to Trinity Bay in Newfoundland. And, except
+    upon one sharp incline about two hundred miles from Valentia, I
+    am not quite sure that it would even be necessary to put the
+    skid on, so gentle are the ascents and descents upon that long
+    route. From Valentia the road would lie down-hill for about two
+    hundred miles to the point at which the bottom is now covered
+    by seventeen hundred fathoms of sea-water. Then would come the
+    central plain, more than a thousand miles wide, the
+    inequalities of the surface of which would be hardly
+    perceptible, though the depth of water upon it now varies from
+    ten thousand to fifteen thousand feet; and there are places in
+    which Mont Blanc might be sunk without showing its peak above
+    water. Beyond this, the ascent on the American side commences,
+    and gradually leads, for about three hundred miles, to the
+    Newfoundland shore.</p>
+
+    <p>Almost the whole of the bottom of this central plain (which
+    extends for many hundred miles in a north and south direction)
+    is covered by a fine mud, which, when brought to the surface,
+    dries into a grayish white friable substance. You can write
+    with this on a black-board, if you are so inclined; and, to the
+    eye, it is quite like very soft, grayish chalk. Examined
+    chemically, it proves to be composed almost wholly of
+    <span class="pagenum"><a name="page182"
+       id="page182"></a>[pg 182]</span> carbonate of lime; and if
+       you make a section of it, in the same way as that of the
+       piece of chalk was made, and view it with the microscope, it
+       presents innumerable Globigerinæ embedded in a granular
+       matrix.</p>
+
+    <p>Thus this deep-sea mud is substantially chalk. I say
+    substantially, because there are a good many minor differences;
+    but as these have no bearing on the question immediately before
+    us&mdash;which is the nature of the Globigerinæ of the
+    chalk&mdash;it is unnecessary to speak of them.</p>
+
+    <p>Globigerinæ of every size, from the smallest to the largest,
+    are associated together in the Atlantic mud, and the chambers
+    of many are filled by a soft animal matter. This soft substance
+    is, in fact, the remains of the creature to which the
+    Globigerina shell, or rather skeleton, owes its
+    existence&mdash;and which is an animal of the simplest
+    imaginable description. It is, in fact, a mere particle of
+    living jelly, without defined parts of any kind&mdash;without a
+    mouth, nerves, muscles, or distinct organs, and only
+    manifesting its vitality to ordinary observation by thrusting
+    out and retracting from all parts of its surface long
+    filamentous processes, which serve for arms and legs. Yet this
+    amorphous particle, devoid of everything which, in the higher
+    animals, we call organs, is capable of feeding, growing, and
+    multiplying; of separating from the ocean the small proportion
+    of carbonate of lime which is dissolved in sea-water; and of
+    building up that substance into a skeleton for itself,
+    according to a pattern which can be imitated by no other known
+    agency.</p>
+
+    <p>The notion that animals can live and flourish in the sea, at
+    the vast depths from which apparently living <span class=
+    "pagenum"><a name="page183"
+       id="page183"></a>[pg 183]</span> Giobigerinæ have been
+       brought up, does not agree very well with our usual
+       conceptions respecting the conditions of animal life; and it
+       is not so absolutely impossible as it might at first sight
+       appear to be, that the Globigerinæ of the Atlantic
+       sea-bottom do not live and die where they are found.</p>
+
+    <div class="figright"
+         style="width:400px;">
+        <a href="images/183.png"><img width="400"
+             src="images/183.png"
+             alt=
+           "DIATOM OOZE DREDGED FROM A DEPTH OF 1950" /></a><br />
+        DIATOM OOZE DREDGED FROM A DEPTH OF 1950 FEET.<br />
+        (Magnified nearly 300 diameters.)
+    </div>
+
+    <p>As I have mentioned, the soundings from the great Atlantic
+    plain are almost entirely made up of Globigerinæ, with the
+    granules which have been mentioned, and some few other
+    calcareous shells; but a small percentage of the chalky
+    mud&mdash;perhaps at most some five per cent of it&mdash;is of
+    a different nature, and consists of shells and skeletons
+    composed of silex, or pure flint. These siliceous bodies belong
+    partly to the lowly vegetable organisms which are called
+    Diatomaceæ, and partly to the minute and extremely simple
+    animals, termed Radiolaria. It is quite certain that these
+    creatures do not live at the bottom of the ocean, but at its
+    surface&mdash;where they may be obtained in prodigious numbers
+    by the use of a properly constructed net. Hence it follows that
+    these siliceous organisms, though they are not heavier than the
+    lightest dust, must have fallen, in some cases, through fifteen
+    thousand feet of water, before they reached their final
+    resting-place on the ocean floor. And, considering how
+    <span class="pagenum"><a name="page184"
+       id="page184"></a>[pg 184]</span> large a surface these
+       bodies expose in proportion to their weight, it is probable
+       that they occupy a great length of time in making their
+       burial journey from the surface of the Atlantic to the
+       bottom.</p>
+
+    <div class="figleft"
+         style="width:400px;">
+        <a href="images/184.png"><img width="400"
+             src="images/184.png"
+             alt="RADIOLARIA." /></a><br />
+        RADIOLARIA.<br />
+        (<i>a.</i> Natural size. <i>b.</i> One-third natural size.)
+    </div>
+
+    <p>But if the Radiolaria and Diatoms are thus rained upon the
+    bottom of the sea, from the superficial layer of its waters in
+    which they pass their lives, it is obviously possible that the
+    Globigerinæ may be similarly derived; and if they were so, it
+    would be much more easy to understand how they obtain their
+    supply of food than it is at present. Nevertheless, the
+    positive and negative evidence all points the other way. The
+    skeletons of the full-grown, deep-sea Globigerinæ are so
+    remarkably solid and heavy in proportion to their surface as to
+    seem little fitted for floating; and, as a matter of fact, they
+    are not to be found along with the Diatoms and Radiolaria, in
+    the uppermost stratum of the open ocean.</p>
+
+    <p>It has been observed, again, that the abundance of
+    Globigerinæ, in proportion to other organisms of like kind,
+    increases with the depth of the sea; and that deep-water
+    Globigerinæ are larger than those which live in the shallower
+    parts of the sea; and such facts negative the supposition that
+    these organisms have been swept by currents from the shallows
+    into the deeps of the Atlantic.</p><span class=
+    "pagenum"><a name="page185"
+       id="page185"></a>[pg 185]</span>
+
+    <p>It therefore seems to be hardly doubtful that these
+    wonderful creatures live and die at the depths in which they
+    are found.<a id="footnotetag2"
+       name="footnotetag2"></a><a href=
+       "#footnote2"><sup>2</sup></a></p>
+
+    <p>However, the important points for us are, that the living
+    Globigerinæ are exclusively marine animals, the skeletons of
+    which abound at the bottom of deep seas; and that there is not
+    a shadow of reason for believing that the habits of the
+    Globigerinæ of the chalk differed from those of the existing
+    species. But if this be true, there is no escaping the
+    conclusion that the chalk itself is the dried mud of an ancient
+    deep sea.</p>
+
+    <p>In working over the soundings collected by Captain Dayman, I
+    was surprised to find that many of what I have called the
+    "granules" of that mud were not, as one might have been tempted
+    to think at first, the mere powder and waste of Globigerinæ,
+    but that they had a definite form and size. I termed these
+    bodies "<i>coccoliths</i>" and doubted their organic nature.
+    Dr. Wallich verified my observation, and added the interesting
+    discovery that, not unfrequently, bodies similar to these
+    "coccoliths" were aggregated together into spheroids, which he
+    termed "<i>coccospheres</i>." So far as we knew, these bodies,
+    the nature of which is extremely <span class=
+       "pagenum"><a name="page186"
+       id="page186"></a>[pg 186]</span> puzzling and problematical,
+       were peculiar to the Atlantic soundings.</p>
+
+    <p>But, a few years ago, Mr. Sorby, in making a careful
+    examination of the chalk by means of thin sections and
+    otherwise, observed, as Ehrenberg had done before him, that
+    much of its granular basis possesses a definite form. Comparing
+    these formed particles with those in the Atlantic soundings, he
+    found the two to be identical; and thus proved that the chalk,
+    like the soundings, contains these mysterious coccoliths and
+    coccospheres. Here was a further and a most interesting
+    confirmation, from internal evidence, of the essential identity
+    of the chalk with modern deep-sea mud. Globigerinæ, coccoliths,
+    and coccospheres are found as the chief constituents of both,
+    and testify to the general similarity of the conditions under
+    which both have been formed.<a id="footnotetag3"
+       name="footnotetag3"></a><a href=
+       "#footnote3"><sup>3</sup></a></p>
+
+    <p>The evidence furnished by the hewing, facing, and
+    superposition of the stones of the Pyramids, that these
+    structures were built by men, has no greater weight than the
+    evidence that the chalk was built by Globigerinæ; and the
+    belief that those ancient pyramid-builders were terrestrial and
+    air-breathing creatures like ourselves, is not better based
+    than the conviction that the chalk-makers lived in the sea.</p>
+
+    <p>But as our belief in the building of the Pyramids by men is
+    not only grounded on the internal evidence afforded by these
+    structures, but gathers strength from multitudinous collateral
+    proofs, and is clinched by the <span class=
+       "pagenum"><a name="page187"
+       id="page187"></a>[pg 187]</span> total absence of any reason
+       for a contrary belief; so the evidence drawn from the
+       Globigerinæ that the chalk is an ancient sea-bottom, is
+       fortified by innumerable independent lines of evidence; and
+       our belief in the truth of the conclusion to which all
+       positive testimony tends, receives the like negative
+       justification from the fact that no other hypothesis has a
+       shadow of foundation.</p>
+
+    <p>It may be worth while briefly to consider a few of these
+    collateral proofs that the chalk was deposited at the bottom of
+    the sea.</p>
+
+    <p>The great mass of the chalk is composed, as we have seen, of
+    the skeletons of Globigerinæ, and other simple organisms,
+    imbedded in granular matter. Here and there, however, this
+    hardened mud of the ancient sea reveals the remains of higher
+    animals which have lived and died, and left their hard parts in
+    the mud, just as the oysters die and leave their shells behind
+    them, in the mud of the present seas.</p>
+
+    <div class="figright"
+         style="width:300px;">
+        <a href="images/187.png"><img width="300"
+             src="images/187.png"
+             alt="UPPER SILURIAN CORALS AND CRUSTACEANS." /></a><br />
+        UPPER SILURIAN CORALS AND CRUSTACEANS.
+    </div>
+
+    <p>There are, at the present day, certain groups of animals
+    which are never found in fresh waters, being unable to live
+    anywhere but in the sea. Such are the corals; those corallines
+    which are called Polyzoa; those creatures which fabricate the
+    lamp-shells, and are called Brachiopoda; the pearly Nautilus,
+    and all animals allied to it; and all the forms of sea-urchins
+    and star-fishes.</p><span class="pagenum"><a name="page188"
+       id="page188"></a>[pg 188]</span>
+
+    <p>Not only are all these creatures confined to salt water at
+    the present day, but, so far as our records of the past go, the
+    conditions of their existence have been the same: hence, their
+    occurrence in any deposit is as strong evidence as can be
+    obtained, that that deposit was formed in the sea. Now the
+    remains of animals of all the kinds which have been enumerated
+    occur in the chalk, in greater or less abundance; while not one
+    of those forms of shell-fish which are characteristic of fresh
+    water has yet been observed in it.</p>
+
+    <p>When we consider that the remains of more than three
+    thousand distinct species of aquatic animals have been
+    discovered among the fossils of the chalk, that the great
+    majority of them are of such forms as are now met with only in
+    the sea, and that there is no reason to believe that any one of
+    them inhabited fresh water&mdash;the collateral evidence that
+    the chalk represents an ancient sea-bottom acquires as great
+    force as the proof derived from the nature of the chalk itself.
+    I think you will now allow that I did not overstate my case
+    when I asserted that we have as strong grounds for believing
+    that all the vast area of dry land at present occupied by the
+    chalk was once at the bottom of the sea, as we have for any
+    matter of history whatever; while there is no justification for
+    any other belief.</p>
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/188.png"><img width="250"
+             src="images/188.png"
+             alt="CRETACEOUS NAUTILUS." /></a>CRETACEOUS NAUTILUS.
+    </div>
+
+    <p>No less certain is it that the time during which the
+    countries we now call southeast England, France, Germany,
+    Poland, Russia, Egypt, Arabia, Syria, were more
+          <span class="pagenum"><a name="page189"
+       id="page189"></a>[pg 189]</span> or less completely covered
+       by a deep sea, was of considerable duration.</p>
+
+    <p>We have already seen that the chalk is, in places, more than
+    a thousand feet thick. I think you will agree with me that it
+    must have taken some time for the skeletons of the animalcules
+    of a hundredth of an inch in diameter to heap up such a mass as
+    that. I have said that throughout the thickness of the chalk
+    the remains of other animals are scattered. These remains are
+    often in the most exquisite state of preservation. The valves
+    of the shell-fishes are commonly adherent; the long spines of
+    some of the sea-urchins, which would be detached by the
+    smallest jar, often remain in their places. In a word, it is
+    certain that these animals have lived and died when the place
+    which they now occupy was the surface of as much of the chalk
+    as had then been deposited; and that each has been covered up
+    by the layer of Globigerina mud, upon which the creatures
+    imbedded a little higher up have, in like manner, lived and
+    died. But some of these remains prove the existence of reptiles
+    of vast size in the chalk sea. These lived their time, and had
+    their ancestors and descendants, which assuredly implies time,
+    reptiles being of slow growth.</p>
+
+    <p>There is more curious evidence, again, that the process of
+    covering up, or, in other words, the deposit of Globigerina
+    skeletons, did not go on very fast. It is demonstrable that an
+    animal of the cretaceous sea might die, that its skeleton might
+    lie uncovered upon the sea-bottom long enough to lose all its
+    outward coverings and appendages by putrefaction; and that,
+    after this had happened, another animal might attach itself
+    <span class="pagenum"><a name="page190"
+       id="page190"></a>[pg 190]</span> to the dead and naked
+       skeleton, might grow to maturity, and might itself die
+       before the calcareous mud had buried the whole.</p>
+
+    <p>Cases of this kind are admirably described by Sir Charles
+    Lyell. He speaks of the frequency with which geologists find in
+    the chalk a fossilized sea-urchin to which is attached the
+    lower valve of a Crania. This is a kind of shell-fish, with a
+    shell composed of two pieces, of which, as in the oyster, one
+    is fixed and the other free.</p>
+
+    <p>"The upper valve is almost invariably wanting, though
+    occasionally found in a perfect state of preservation in the
+    white chalk at some distance. In this case, we see clearly that
+    the sea-urchin first lived from youth to age, then died and
+    lost its spines, which were carried away. Then the young Crania
+    adhered to the bared shell, grew and perished in its turn;
+    after which, the upper valve was separated from the lower,
+    before the Echinus became enveloped in chalky mud."</p>
+
+    <p>A specimen in the Museum of Practical Geology, in London,
+    still further prolongs the period which must have elapsed
+    between the death of the sea-urchin and its burial by the
+    Globigeringæ. For the outward face of the valve of a Crania,
+    which is attached to a sea-urchin (Micrastor), is itself
+    overrun by an incrusting coralline, which spreads thence over
+    more or less of the surface of the sea-urchin. It follows that,
+    after the upper valve of the Crania fell off, the surface of
+    the attached valve must have remained exposed long enough to
+    allow of the growth of the whole coralline, since corallines do
+    not live imbedded in the mud.</p>
+
+    <p>The progress of knowledge may, one day, enable us
+    <span class="pagenum"><a name="page191"
+       id="page191"></a>[pg 191]</span> to deduce from such facts
+       as these the maximum rate at which the chalk can have
+       accumulated, and thus to arrive at the minimum duration of
+       the chalk period. Suppose that the valve of the Crania upon
+       which a coralline has fixed itself in the way just described
+       is so attached to the sea-urchin that no part of it is more
+       than an inch above the face upon which the sea-urchin rests.
+       Then, as the coralline could not have fixed itself if the
+       Crania had been covered up with chalk-mud, and could not
+       have lived had itself been so covered, it follows, that an
+       inch of chalk mud could not have accumulated within the time
+       between the death and decay of the soft parts of the
+       sea-urchin and the growth of the coralline to the full size
+       which it has attained. If the decay of the soft parts of the
+       sea-urchin; the attachment, growth to maturity, and decay of
+       the Crania; and the subsequent attachment and growth of the
+       coralline, took a year (which is a low estimate enough), the
+       accumulation of the inch of chalk must have taken more than
+       a year: and the deposit of a thousand feet of chalk must,
+       consequently, have taken more than twelve thousand
+       years.</p>
+
+    <p>The foundation of all this calculation is, of course, a
+    knowledge of the length of time the Crania and the coralline
+    needed to attain their full size; and, on this head, precise
+    knowledge is at present wanting. But there are circumstances
+    which tend to show that nothing like an inch of chalk has
+    accumulated during the life of a Crania; and, on any probable
+    estimate of the length of that life, the chalk period must have
+    had a much longer duration than that thus roughly assigned to
+    it.</p><span class="pagenum"><a name="page192"
+       id="page192"></a>[pg 192]</span>
+
+    <p>Thus, not only is it certain that the chalk is the mud of an
+    ancient sea-bottom; but it is no less certain that the chalk
+    sea existed during an extremely long period, though we may not
+    be prepared to give a precise estimate of the length of that
+    period in years. The relative duration is clear, though the
+    absolute duration may not be definable. The attempt to affix
+    any precise date to the period at which the chalk sea began or
+    ended its existence, is baffled by difficulties of the same
+    kind. But the relative age of the cretaceous epoch may be
+    determined with as great ease and certainty as the long
+    duration of that epoch.</p>
+
+    <p>You will have heard of the interesting discoveries recently
+    made, in various parts of Western Europe, of flint implements,
+    obviously worked into shape by human hands, under circumstances
+    which show conclusively that man is a very ancient denizen of
+    these regions.</p>
+
+    <p>It has been proved that the old populations of Europe, whose
+    existence has been revealed to us in this way, consisted of
+    savages, such as the Esquimaux are now; that, in the country
+    which is now France, they hunted the reindeer, and were
+    familiar with the ways of the mammoth and the bison. The
+    physical geography of France was in those days different from
+    what it is now&mdash;the river Somme, for instance, having cut
+    its bed a hundred feet deeper between that time and this; and
+    it is probable that the climate was more like that of Canada or
+    Siberia than that of Western Europe.</p>
+
+    <p>The existence of these people is forgotten even in the
+    traditions of the oldest historical nations. The name
+    <span class="pagenum"><a name="page193"
+       id="page193"></a>[pg 193]</span> and fame of them had
+       utterly vanished until a few years back; and the amount of
+       physical change which has been effected since their day
+       renders it more than probable that, venerable as are some of
+       the historical nations, the workers of the chipped flints of
+       Hoxne or of Amiens are to them, as they are to us, in point
+       of antiquity.</p>
+
+    <p>But, if we assign to these hoar relics of long-vanished
+    generations of men the greatest age that can possibly be
+    claimed for them, they are not older than the drift, or boulder
+    clay, which, in comparison with the chalk, is but a very
+    juvenile deposit. You need go no further than your own seaboard
+    for evidence of this fact. At one of the most charming spots on
+    the coast of Norfolk, Cromer, you will see the boulder clay
+    forming a vast mass, which lies upon the chalk, and must
+    consequently have come into existence after it. Huge boulders
+    of chalk are, in fact, included in the clay, and have evidently
+    been brought to the position they now occupy by the same agency
+    as that which has planted blocks of syenite from Norway side by
+    side with them.</p>
+
+    <p>The chalk, then, is certainly older than the boulder clay.
+    If you ask how much, I will again take you no further than the
+    same spot upon your own coasts for evidence. I have spoken of
+    the boulder clay and drift as resting upon the chalk. That is
+    not strictly true. Interposed between the chalk and the drift
+    is a comparatively insignificant layer, containing vegetable
+    matter. But that layer tells a wonderful history. It is full of
+    stumps of trees standing as they grew. Fir-trees are there with
+    their cones, and hazel-bushes with their nuts; there stand the
+    stools of oak and yew trees, <span class="pagenum"><a name=
+    "page194"
+       id="page194"></a>[pg 194]</span> beeches and alders. Hence
+       this stratum is appropriately called the "forest-bed."</p>
+
+    <p>It is obvious that the chalk must have been upheaved and
+    converted into dry land before the timber trees could grow upon
+    it. As the bolls of some of these trees are from two to three
+    feet in diameter, it is no less clear that the dry land thus
+    formed remained in the same condition for long ages. And not
+    only do the remains of stately oaks and well-grown firs testify
+    to the duration of this condition of things, but additional
+    evidence to the same effect is afforded by the abundant remains
+    of elephants, rhinoceroses, hippopotamuses, and other great
+    wild beasts, which it has yielded to the zealous search of such
+    men as the Rev. Mr. Gunn.</p>
+
+    <p>When you look at such a collection as he has formed, and
+    bethink you that these elephantine bones did veritably carry
+    their owners about, and these great grinders crunch, in the
+    dark woods of which the forest-bed is now the only trace, it is
+    impossible not to feel that they are as good evidence of the
+    lapse of time as the annual rings of the tree-stumps.</p>
+
+    <p>Thus there is a writing upon the wall of cliffs at Cromer,
+    and whoso runs may read it. It tells us, with an authority
+    which cannot be impeached, that the ancient sea-bed of the
+    chalk sea was raised up, and remained dry land, until it was
+    covered with forest, stocked with the great game whose spoils
+    have rejoiced your geologists. How long it remained in that
+    condition cannot be said; but "the whirligig of time brought
+    its revenges" in those days as in these. That dry land, with
+    the bones and teeth of generations of <span class=
+    "pagenum"><a name="page195"
+       id="page195"></a>[pg 195]</span> long-lived elephants,
+       hidden away among the gnarled roots and dry leaves of its
+       ancient trees, sank gradually to the bottom of the icy sea,
+       which covered it with huge masses of drift and boulder clay.
+       Sea-beasts, such as the walrus, now restricted to the
+       extreme north, paddled about where birds had twittered among
+       the topmost twigs of the fir-trees. How long this state of
+       things endured we know not, but at length it came to an end.
+       The upheaved glacial mud hardened into the soil of modern
+       Norfolk. Forests grew once more, the wolf and the beaver
+       replaced the reindeer and the elephant; and at length what
+       we call the history of England dawned.</p>
+
+    <p>Thus you have, within the limits of your own county, proof
+    that the chalk can justly claim a very much greater antiquity
+    than even the oldest physical traces of mankind. But we may go
+    further and demonstrate, by evidence of the same authority as
+    that which testifies to the existence of the father of men,
+    that the chalk is vastly older than Adam himself.</p>
+
+    <p>The Book of Genesis informs us that Adam, immediately upon
+    his creation, and before the appearance of Eve, was placed in
+    the garden of Eden. The problem of the geographical position of
+    Eden has greatly vexed the spirits of the learned in such
+    matters, but there is one point respecting which, so far as I
+    know, no commentator has ever raised a doubt. This is, that of
+    the four rivers which are said to run out of it, Euphrates and
+    Hiddekel are identical with the rivers now known by the names
+    of Euphrates and Tigris.</p>
+
+    <p>But the whole country in which these mighty rivers take
+    their origin, and through which they run, is <span class=
+    "pagenum"><a name="page196"
+       id="page196"></a>[pg 196]</span> composed of rocks which are
+       either of the same age as the chalk, or of later date. So
+       that the chalk must not only have been formed, but, after
+       its formation, the time required for the deposit of these
+       later rocks, and for their upheaval into dry land, must have
+       elapsed, before the smallest brook which feeds the swift
+       stream of "the great river, the river of Babylon," began to
+       flow.</p>
+    <hr />
+
+    <p>Thus, evidence which cannot be rebutted, and which need not
+    be strengthened, though if time permitted I might indefinitely
+    increase its quantity, compels you to believe that the earth,
+    from the time of the chalk to the present day, has been the
+    theatre of a series of changes as vast in their amount as they
+    were slow in their progress. The area on which we stand has
+    been first sea and then land, for at least four alternations;
+    and has remained in each of these conditions for a period of
+    great length.</p>
+
+    <p>Nor have these wonderful metamorphoses of sea into land, and
+    of land into sea, been confined to one corner of England.
+    During the chalk period, or "cretaceous epoch," not one of the
+    present great physical features of the globe was in existence.
+    Our great mountain ranges, Pyrenees, Alps, Himalayas, Andes,
+    have all been upheaved since the chalk was deposited, and the
+    cretaceous sea flowed over the sites of Sinai and Ararat.</p>
+
+    <p>All this is certain, because rocks of cretaceous or still
+    later date have shared in the elevatory movements which gave
+    rise to these mountain chains; and may be found perched up, in
+    some cases, many thousand feet <span class=
+       "pagenum"><a name="page197"
+       id="page197"></a>[pg 197]</span> high upon their flanks. And
+       evidence of equal cogency demonstrates that, though in
+       Norfolk the forest-bed rests directly upon the chalk, yet it
+       does so, not because the period at which the forest grew
+       immediately followed that at which the chalk was formed, but
+       because an immense lapse of time, represented elsewhere by
+       thousands of feet of rock, is not indicated at Cromer.</p>
+
+    <p>I must ask you to believe that there is no less conclusive
+    proof that a still more prolonged succession of similar changes
+    occurred before the chalk was deposited. Nor have we any reason
+    to think that the first term in the series of these changes is
+    known. The oldest sea-beds preserved to us are sands, and mud,
+    and pebbles, the wear and tear of rocks which were formed in
+    still older oceans.</p>
+
+    <p>But, great as is the magnitude of these physical changes of
+    the world, they have been accompanied by a no less striking
+    series of modifications in its living inhabitants.</p>
+
+    <p>All the great classes of animals, beasts of the field, fowls
+    of the air, creeping things, and things which dwell in the
+    waters, flourished upon the globe long ages before the chalk
+    was deposited. Very few, however, if any, of these ancient
+    forms of animal life were identical with those which now live.
+    Certainly not one of the higher animals was of the same species
+    as any of those now in existence. The beasts of the field, in
+    the days before the chalk, were not our beasts of the field,
+    nor the fowls of the air such as those which the eye of man has
+    seen flying, unless his antiquity dates infinitely further back
+    than we at present surmise. If we could <span class=
+    "pagenum"><a name="page198"
+       id="page198"></a>[pg 198]</span> be carried back into those
+       times, we should be as one suddenly set down in Australia
+       before it was colonized. We should see mammals, birds,
+       reptiles, fishes, insects, snails, and the like, clearly
+       recognizable as such, and yet not one of them would be just
+       the same as those with which we are familiar, and many would
+       be extremely different.</p>
+
+    <p>From that time to the present, the population of the world
+    has undergone slow and gradual, but incessant, changes. There
+    has been no grand catastrophe&mdash;no destroyer has swept away
+    the forms of life of one period, and replaced them by a totally
+    new creation; but one species has vanished and another has
+    taken its place; creatures of one type of structure have
+    diminished, those of another have increased, as time has passed
+    on. And thus, while the differences between the living
+    creatures of the time before the chalk and those of the present
+    day appear startling, if placed side by side, we are led from
+    one to the other by the most gradual progress, if we follow the
+    course of Nature through the whole series of those relics of
+    her operations which she has left behind.</p>
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/198.png"><img width="200"
+             src="images/198.png"
+             alt="SKELETON OF THE PTERODACTYL." /></a><br />
+        SKELETON OF THE PTERODACTYL.
+    </div>
+
+    <p>And it is by the population of the chalk sea that the
+    ancient and the modern inhabitants of the world are most
+    completely connected. The groups which are dying out flourish,
+    side by side, with the groups which are now the dominant forms
+    of life.</p>
+
+    <p>Thus the chalk contains remains of those flying and
+    <span class="pagenum"><a name="page199"
+       id="page199"></a>[pg 199]</span> swimming reptiles, the
+       pterodactyl, the ichthyosaurus, and the plesiosaurus, which
+       are found in no later deposits, but abounded in preceding
+       ages. The chambered shells called ammonites and belemnites,
+       which are so characteristic of the period preceding the
+       cretaceous, in like manner die with it.</p>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/199-1.png"><img width="600"
+             src="images/199-1.png"
+             alt="THE SKELETON OF THE ICHTHYOSAURUS." /></a><br />
+        THE SKELETON OF THE ICHTHYOSAURUS.
+    </div>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/199-2.png"><img width="600"
+             src="images/199-2.png"
+             alt="THE SKELETON OF THE PLESIOSAURUS." /></a><br />
+        THE SKELETON OF THE PLESIOSAURUS.
+    </div>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/199-3.png"><img width="600"
+             src="images/199-3.png"
+             alt="AMMONITES." /></a><br />
+        AMMONITES.
+    </div>
+
+    <p>But, among these fading remainders of a previous state of
+    things, are some very modern forms of life, looking like Yankee
+    peddlers among a tribe of red Indians. Crocodiles of modern
+    type appear; bony fishes, many of them very similar to existing
+    species, almost supplant the forms of fish which predominate in
+    more ancient seas; and many kinds of living shell-fish
+    <span class="pagenum"><a name="page200"
+       id="page200"></a>[pg 200]</span> first become known to us in
+       the chalk. The vegetation acquires a modern aspect. A few
+       living animals are not even distinguishable as species from
+       those which existed at that remote epoch. The Globigerina of
+       the present day, for example, is not different specifically
+       from that of the chalk; and the same may be said of many
+       other Foraminifera. I think it probable that critical and
+       unprejudiced examination will show that more than one
+       species of much higher animals have had a similar longevity;
+       but the only example which I can at present give confidently
+       is the snake's-head lamp-shell (<i>Terebratulina caput
+       serpentis</i>), which lives in our English seas and abounded
+       (as <i>Terebratulina striata</i> of authors) in the
+       chalk.</p>
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/200-1.png"><img width="200"
+             src="images/200-1.png"
+             alt="BELEMNITES." /></a><br />
+        BELEMNITES.
+    </div>
+
+    <div class="figright"
+         style="width:200px;">
+        <a href="images/200-2.png"><img width="200"
+             src="images/200-2.png"
+             alt="TEREBRATULINA." /></a><br />
+        TEREBRATULINA.
+    </div>
+
+    <p>The longest line of human ancestry must hide its diminished
+    head before the pedigree of this insignificant shell-fish. We
+    Englishmen are proud to have an ancestor who was present at the
+    Battle of Hastings. The ancestors of <i>Terebratulina caput
+    serpentis</i> may have been present at a battle of
+    Ichthyosauria in that part of the sea which, when the chalk was
+    forming, flowed over the site of Hastings. While all around has
+    changed, this Terebratulina has peacefully propagated its
+    species from generation to generation, and stands to this day
+    as a living testimony to the <span class="pagenum"><a name=
+    "page201"
+       id="page201"></a>[pg 201]</span> continuity of the present
+       with the past history of the globe.</p>
+    <hr />
+
+    <p>Up to this moment I have stated, so far as I know, nothing
+    but well-authenticated facts, and the immediate conclusions
+    which they force upon the mind.</p>
+
+    <p>But the mind is so constituted that it does not willingly
+    rest in facts and immediate causes, but seeks always after a
+    knowledge of the remoter links in the chain of causation.</p>
+
+    <p>Taking the many changes of any given spot of the earth's
+    surface, from sea to land, and from land to sea, as an
+    established fact, we cannot refrain from asking ourselves how
+    these changes have occurred. And when we have explained
+    them&mdash;as they must be explained&mdash;by the alternate
+    slow movements of elevation and depression which have affected
+    the crusts of the earth, we go still further back, and ask, Why
+    these movements?</p>
+
+    <p>I am not certain that any one can give you a satisfactory
+    answer to that question. Assuredly I cannot. All that can be
+    said for certain is, that such movements are part of the
+    ordinary course of nature, inasmuch as they are going on at the
+    present time. Direct proof may be given, that some parts of the
+    land of the northern hemisphere are at this moment insensibly
+    rising and others insensibly sinking; and there is indirect but
+    perfectly satisfactory proof, that an enormous area now covered
+    by the Pacific has been deepened thousands of feet since the
+    present inhabitants of that sea came into existence.</p>
+
+    <p>Thus there is not a shadow of a reason for believing
+    <span class="pagenum"><a name="page202"
+       id="page202"></a>[pg 202]</span> that the physical changes
+       of the globe, in past times, have been effected by other
+       than natural causes.</p>
+
+    <p>Is there any more reason for believing that the concomitant
+    modifications in the forms of the living inhabitants of the
+    globe have been brought about in any other ways?</p>
+
+    <p>Before attempting to answer this question, let us try to
+    form a distinct mental picture of what has happened in some
+    special case.</p>
+
+    <p>The crocodiles are animals which, as a group, have a very
+    vast antiquity. They abounded ages before the chalk was
+    deposited; they throng the rivers in warm climates at the
+    present day. There is a difference in the form of the joints of
+    the backbone, and in some minor particulars, between the
+    crocodiles of the present epoch and those which lived before
+    the chalk; but, in the cretaceous epoch, as I have already
+    mentioned, the crocodiles had assumed the modern type of
+    structure. Notwithstanding this, the crocodiles of the chalk
+    are not identically the same as those which lived in the times
+    called "older tertiary," which succeeded the cretaceous epoch;
+    and the crocodiles of the older tertiaries are not identical
+    with those of the newer tertiaries, nor are these identical
+    with existing forms. I leave open the question whether
+    particular species may have lived on from epoch to epoch. But
+    each epoch has had its peculiar crocodiles; though all, since
+    the chalk, have belonged to the modern type, and differ simply
+    in their proportions and in such structural particulars as are
+    discernible only to trained eyes.</p>
+
+    <p>How is the existence of this long succession of different
+    species of crocodiles to be accounted
+          for?</p><span class="pagenum"><a name="page203"
+       id="page203"></a>[pg 203]</span>
+
+    <p>Only two suppositions seem to be open to us&mdash;either
+    each species of crocodile has been specially created, or it has
+    arisen out of some pre-existing form by the operation of
+    natural causes.</p>
+
+    <p>Choose your hypothesis; I have chosen mine. I can find no
+    warranty for believing in the distinct creation of a score of
+    successive species of crocodiles in the course of countless
+    ages of time. Science gives no countenance to such a wild
+    fancy; nor can even the perverse ingenuity of a commentator
+    pretend to discover this sense, in the simple wrords in which
+    the writer of Genesis records the proceeding of the fifth and
+    sixth days of the Creation.</p>
+
+    <p>On the other hand, I see no good reason for doubting the
+    necessary alternative, that all these varied species have been
+    evolved from pre-existing crocodilian forms by the operation of
+    causes as completely a part of the common order of nature as
+    those which have effected the changes of the inorganic
+    world.</p>
+
+    <p>Few will venture to affirm that the reasoning which applies
+    to crocodiles loses its force among other animals or among
+    plants. If one series of species has come into existence by the
+    operation of natural causes, it seems folly to deny that all
+    may have arisen in the same way.</p>
+    <hr />
+
+    <p>A small beginning has led us to a great ending. If I were to
+    put the bit of chalk with which we started into the hot but
+    obscure flame of burning hydrogen, it would presently shine
+    like the sun. It seems to me that this physical metamorphosis
+    is no false image of what has been the result of our subjecting
+    it to a jet <span class="pagenum"><a name="page204"
+       id="page204"></a>[pg 204]</span> of fervent, though nowise
+       brilliant, thought to-night. It has become luminous, and its
+       clear rays, penetrating the abyss of the remote past, have
+       brought within our ken some stages of the evolution of the
+       earth. And in the shifting "without haste, but without rest"
+       of the land and sea, as in the endless variation of the
+       forms assumed by living beings, we have observed nothing but
+       the natural product of the forces originally possessed by
+       the substance of the universe.</p>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/204.png"><img width="400"
+             src="images/204.png"
+             alt="Cliffs above the sea." /></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="page205"
+       id="page205"></a>[pg 205]</span>
+
+    <h2>A BIT OF SPONGE</h2>
+
+    <h4>(Written on Scotland.)</h4>
+
+    <h4>(<span class="sc">From Glimpses of Nature.</span>)</h4>
+
+    <h3><span class="sc">By</span> A. WILSON.</h3>
+    <hr class="short" />
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/205.png"><img width="200"
+             src="images/205.png"
+             alt="Fishing for sponges." /></a>
+    </div>
+
+    <p>This morning, despite the promise of rain over-night, has
+    broken with all the signs and symptoms of a bright July day.
+    The Firth is bathed in sunlight, and the wavelets at full tide
+    are kissing the strand, making a soft musical ripple as they
+    retire, and as the pebbles run down the sandy slope on the
+    retreat of the waves. Beyond the farthest contact of the tide
+    is a line of seaweed dried and desiccated, mixed up with which,
+    in confusing array, are masses of shells, and such <i>olla
+    podrida</i> of the sea.</p>
+
+    <p>Tossed up at our very feet is a dried fragment of sponge,
+    which doubtless the unkind waves tore from its rocky bed. It is
+    not a large portion of sponge this, but its structure is
+    nevertheless to be fairly made out, and some reminiscences of
+    its history gleaned, for the sake of occupying the by no means
+    "bad half-hour" before breakfast. "What is a sponge?" is a
+    question <span class="pagenum"><a name="page206"
+       id="page206"></a>[pg 206]</span> which you may well ask as a
+       necessary preliminary to the understanding of its
+       personality.</p><br clear="all" />
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/206.png"><img width="250"
+             src="images/206.png"
+             alt="A SPONGE ATTACHED TO ITS ROCKY BED." /></a><br />
+        A SPONGE ATTACHED TO ITS ROCKY BED.
+    </div>
+
+    <p>The questionings of childhood and the questionings of
+    science run in precisely similar grooves. "What is it?" and
+    "How does it live?" and "Where does it come from?" are equally
+    the inquiries of childhood, and of the deepest philosophy which
+    seeks to determine the whole history of life. This morning, we
+    cannot do better than follow in the footsteps of the child, and
+    to the question, "What is a sponge?" I fancy science will be
+    able to return a direct answer. First of all, we may note that
+    a sponge, as we know it in common life, is the horny skeleton
+    or framework which was made by, and which supported, the living
+    parts. These living parts consist of minute masses of that
+    living jelly to which the name of <i>protoplasm</i> has been
+    applied. This, in truth, is the universal matter of life. It is
+    the one substance with which life everywhere is associated, and
+    as we see it simply in the sponge, so also we behold it (only
+    in more complex guise) in the man. Now, the living parts of
+    this dried cast-away sponge were found both <span class=
+    "pagenum"><a name="page207"
+       id="page207"></a>[pg 207]</span> in its interior and on its
+       surface. They lined the canals that everywhere permeate the
+       sponge-substance, and microscopic examination has told us a
+       great deal about their nature.</p>
+
+    <div class="figright"
+         style="width:400px;">
+        <a href="images/207.png"><img width="400"
+             src="images/207.png"
+             alt=
+           "FIG. 1. DEVELOPMENT OF A SPONGE (Olynthus)." /></a><br />
+        FIG. 1. DEVELOPMENT OF A SPONGE (<i>Olynthus</i>).
+
+        <p>1. The egg. 2, 3, and 4. The process of egg-division. 5
+        and 6. The gastrula-stage. 7. The perfect sponge.</p>
+    </div>
+
+    <p>For, whether found in the canals of the sponge themselves,
+    or embedded in the sponge-substance, the living
+    sponge-particles are represented each by a semi-independent
+    mass of protoplasm. So that the first view I would have you
+    take of the sponge as a living mass, is, that it is a colony
+    and not a single unit. It is composed, in other words, of
+    aggregated masses of living particles, which bud out one from
+    the other, and manufacture the supporting skeleton we know as
+    "the sponge of commerce" itself. Under the microscope, these
+    living sponge-units appear in various guises and shapes. Some
+    of them are formless, and, as to shape, ever-altering masses,
+    resembling that familiar animalcule of our pools we know as the
+    <i>Amoeba</i>. These members of the sponge-colony form the bulk
+    of the population. They are embedded in the sponge substance;
+    they wander about through the meshes of the sponge;
+          <span class="pagenum"><a name="page208"
+       id="page208"></a>[pg 208]</span> they seize food and
+       flourish and grow; and they probably also give origin to the
+       "eggs" from which new sponges are in due course
+       produced.</p>
+
+    <p>More characteristic however, are certain units of this
+    living sponge-colony which live in the lining membrane of the
+    canals. In point of fact, a sponge is a kind of Venice, a
+    certain proportion of whose inhabitants, like those of the
+    famous Queen of the Adriatic herself, live on the banks of the
+    waterways. Just as in Venice we find the provisions for the
+    denizens of the city brought to the inhabitants by the canals,
+    so from the water, which, as we shall see, is perpetually
+    circulating through a sponge, the members of the sponge-colony
+    receive their food.</p>
+
+    <p>Look, again, at the sponge-fragment which lies before us.
+    You perceive half a dozen large holes or so, each opening on a
+    little eminence, as it were. These apertures, bear in mind, we
+    call <i>oscula</i>. They are the exits of the sponge-domain.
+    But a close inspection of a sponge shows that it is riddled
+    with finer and smaller apertures. These latter are the
+    <i>pores</i>, and they form the entrances to the
+    sponge-domain.</p>
+
+    <p>On the banks of the canal you may see growing plentifully in
+    summer time a green sponge, which is the common fresh-water
+    species. Now, if you drop a living specimen of this species
+    into a bowl of water, and put some powdered indigo into the
+    water, you may note how the currents are perpetually being
+    swept in by the pores and out by the oscula. In every living
+    sponge this perpetual and unceasing circulation of water
+    proceeds. This is the sole evidence the unassisted sight
+    receives of the vitality of the sponge-colony,
+          <span class="pagenum"><a name="page209"
+       id="page209"></a>[pg 209]</span> and the importance of this
+       circulation in aiding life in these depths, to be fairly
+       carried out cannot readily be over-estimated.</p>
+
+    <div class="figcenter"
+         style="width:300px;">
+        <a href="images/233.jpg"><img width="300"
+             src="images/233sm.jpg"
+             alt="WHERE SPONGES GROW." /></a><br />
+        WHERE SPONGES GROW.
+    </div>
+
+    <p>Let us now see how this circulation is maintained.
+    Microscopically regarded, we see here and there, in the sides
+    of the sponge-passages, little chambers and recesses which
+    remind one of the passing-places in a narrow canal. Lining
+    these chambers, we see living sponge-units of a type different
+    from the shapeless specks we noted to occur in the meshes of
+    the sponge substance itself. The units of the recesses each
+    consist of a living particle, whose free extremity is raised
+    into a kind of collar, from which projects a lash-like filament
+    known as a flagellum.</p>
+
+    <p>This lash is in constant movement. It waves to and fro in
+    the water, and the collection of lashes we see in any one
+    chamber acts as a veritable brush, which by its movement not
+    only sweeps water in by the pores, but sends it onwards through
+    the sponge, and in due time sends it out by the bigger holes,
+    or oscula. This constant circulation in the sponge discharges
+    more than one important function. For, as already noted, it
+    serves the purpose of nutrition, in that the particles on which
+    sponge-life is supported are swept into the colony.</p>
+
+    <p>Again, the fresh currents of water carry with them the
+    oxygen gas which is a necessity of sponge existence, as of
+    human life; while, thirdly, waste matters, inevitably alike in
+    sponge and in man as the result of living, are swept out of the
+    colony, and discharged into the sea beyond. Our bit of sponge
+    has thus grown from a mere dry fragment into a living reality.
+    It is a <span class="pagenum"><a name="page210"
+       id="page210"></a>[pg 210]</span> community in which already,
+       low as it is, the work of life has come to be discharged by
+       distinct and fairly specialized beings.</p>
+
+    <p>The era of new sponge-life is inaugurated by means of
+    egg-development, although there exists another fashion (that of
+    gemmules or buds) whereby out of the parental substance young
+    sponges are produced. A sponge-egg develops, as do all eggs, in
+    a definite cycle. It undergoes division (Fig. 1); its one cell
+    becomes many; and its many cells arrange themselves first of
+    all into a cup-like form (5, 6 and 7), which may remain in this
+    shape if the sponge is a simple one, or become developed into
+    the more complex shape of the sponges we know.</p>
+
+    <p>In every museum you may see specimens of a beautiful
+    vase-like structure seemingly made of spun-glass. This is a
+    flinty sponge, the "Venus flower-basket," whose presence in the
+    sponge family redeems it from the charge that it contains no
+    things of beauty whatever. So, too, the rocks are full of
+    fossil-sponges, many of quaint form. Our piece of sponge, as we
+    may understand, has yet other bits of history attached to
+    it.... Meanwhile, think over the sponge and its ways, and learn
+    from it that out of the dry things of life, science weaves many
+    a fairy tale.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/210.png"><img width="500"
+             src="images/210.png"
+             alt="Under the sea." /></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="page211"
+       id="page211"></a>[pg 211]</span>
+
+    <h2>THE GREATEST SEA-WAVE EVER KNOWN</h2>
+
+    <h4>(<span class="sc">From Light Science in Leisure
+    Hours.</span>)</h4>
+
+    <h3><span class="sc">By</span> R.A. PROCTOR.</h3>
+    <hr class="short" />
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/211.png"><img width="200"
+             src="images/211.png"
+             alt="sea wave" /></a>
+    </div>
+
+    <p>August 13th, 1868, one of the most terrible calamities which
+    has ever visited a people befell the unfortunate inhabitants of
+    Peru. In that land earthquakes are nearly as common as rain
+    storms are with us; and shocks by which whole cities are
+    changed into a heap of ruins are by no means infrequent. Yet
+    even in Peru, "the land of earthquakes," as Humboldt has termed
+    it, no such catastrophe as that of August, 1868, had occurred
+    within the memory of man. It was not one city which was laid in
+    ruins, but a whole empire. Those who perished were counted by
+    tens of thousands, while the property destroyed by the
+    earthquake was valued at millions of pounds sterling.</p>
+
+    <p>Although so many months have passed since this terrible
+    calamity took place, scientific men have been busily engaged,
+    until quite recently, in endeavoring to <span class=
+    "pagenum"><a name="page212"
+       id="page212"></a>[pg 212]</span> ascertain the real
+       significance of the various events which were observed
+       during and after the occurrence of the earthquake. The
+       geographers of Germany have taken a special interest in
+       interpreting the evidence afforded by this great
+       manifestation of Nature's powers. Two papers have been
+       written recently on the great earthquake of August 13th,
+       1868&mdash;one by Professor von Hochsteter, the other by
+       Herr von Tschudi, which present an interesting account of
+       the various effects, by land and by sea, which resulted from
+       the tremendous upheaving force to which the western flanks
+       of the Peruvian Andes were subjected on that day. The
+       effects on land, although surprising and terrible, only
+       differ in degree from those which have been observed in
+       other earthquakes. But the progress of the great sea-wave
+       which was generated by the upheaval of the Peruvian shores
+       and propagated over the whole of the Pacific Ocean differs
+       altogether from any earthquake phenomena before observed.
+       Other earthquakes have indeed been followed by oceanic
+       disturbances; but these have been accompanied by terrestrial
+       motions, so as to suggest the idea that they had been caused
+       by the motion of the sea-bottom or of the neighboring land.
+       In no instance has it ever before been known that a
+       well-marked wave of enormous proportions should have been
+       propagated over the largest ocean tract on our globe by an
+       earth-shock whose direct action was limited to a relatively
+       small region, and that region not situated in the centre,
+       but on one side of the wide area traversed by the wave.</p>
+
+    <p>We propose to give a brief sketch of the history of this
+    enormous sea-wave. In the first place, however,
+          <span class="pagenum"><a name="page213"
+       id="page213"></a>[pg 213]</span> it may be well to remind
+       the reader of a few of the more prominent features of the
+       great shock to which this wave owed its origin.</p>
+
+    <p>It was at Arequipa, at the foot of the lofty volcanic
+    mountain Misti, that the most terrible effects of the great
+    earthquake were experienced. Within historic times Misti has
+    poured forth no lava streams, but that the volcano is not
+    extinct is clearly evidenced by the fact that in 1542 an
+    enormous mass of dust and ashes was vomited forth from its
+    crater. On August 13th. 1868, Misti showed no signs of being
+    disturbed. So far as the volcanic neighbor was concerned, the
+    forty-four thousand inhabitants of Arequipa had no reason to
+    anticipate the catastrophe which presently befell them. At five
+    minutes past five an earthquake shock was experienced, which,
+    though severe, seems to have worked little mischief. Half a
+    minute later, however, a terrible noise was heard beneath the
+    earth; a second shock more violent than the first was felt, and
+    then began a swaying motion, gradually increasing in intensity.
+    In the-course of the first minute this motion had become so
+    violent that the inhabitants ran in terror out of their houses
+    into the streets and squares. In the next two minutes the
+    swaying movement had so increased that the more lightly built
+    houses were cast to the ground, and the flying people could
+    scarcely keep their feet. "And now," says Von Tschudi, "there
+    followed during two or three minutes a terrible scene. The
+    swaying motion which had hitherto prevailed changed into fierce
+    vertical upheaval. The subterranean roaring increased in the
+    most terrifying manner; then were heard the heart-piercing
+    shrieks of the <span class="pagenum"><a name="page214"
+       id="page214"></a>[pg 214]</span> wretched people, the
+       bursting of walls, the crashing fall of houses and churches,
+       while over all rolled thick clouds of a yellowish-black
+       dust, which, had they been poured forth many minutes longer,
+       would have suffocated thousands." Although the shocks had
+       lasted but a few minutes, the whole town was destroyed. Not
+       one building remained uninjured, and there were few which
+       did not lie in shapeless heaps of ruins.</p>
+
+    <p>At Tacna and Arica the earth-shock was less severe, but
+    strange and terrible phenomena followed it. At the former place
+    a circumstance occurred the cause and nature of which yet
+    remain a mystery. About three hours after the
+    earthquake&mdash;in other words, at about eight o'clock in the
+    evening&mdash;an intensely brilliant light made its appearance
+    above the neighboring mountains. It lasted for fully half an
+    hour, and has been ascribed to the eruption of some as yet
+    unknown volcano.</p>
+
+    <p>At Arica the sea-wave produced even more destructive effects
+    than had been caused by the earthquake. About twenty minutes
+    after the first earth-shock the sea was seen to retire, as if
+    about to leave the shores wholly dry; but presently its waters
+    returned with tremendous force. A mighty wave, whose length
+    seemed immeasurable, was seen advancing like a dark wall upon
+    the unfortunate town, a large part of which was overwhelmed by
+    it. Two ships, the Peruvian corvette America, and the United
+    States "double-ender" Wateree, were carried nearly half a mile
+    to the north of Arica beyond the railroad which runs to Tacna,
+    and there left stranded high and dry. This enormous wave was
+    considered by the English vice-consul at Arica to have been
+    fully fifty feet in height.</p><span class=
+       "pagenum"><a name="page215"
+       id="page215"></a>[pg 215]</span>
+
+    <p>At Chala three such waves swept in after the first shocks of
+    earthquake. They overflowed nearly the whole of the town, the
+    sea passing more than half a mile beyond its usual limits.</p>
+
+    <p>At Islay and Iquique similar phenomena were manifested. At
+    the former town the lava flowed in no less than five times, and
+    each time with greater force. Afterward the motion gradually
+    diminished, but even an hour and a half after the commencement
+    of this strange disturbance the waves still ran forty feet
+    above the ordinary level. At Iquique the people beheld the
+    inrushing wave while it was still a great way off. A dark blue
+    mass of water some fifty feet in height was seen sweeping in
+    upon the town with inconceivable rapidity. An island lying
+    before the harbor was completely submerged by the great wave,
+    which still came rushing on black with the mud and slime it had
+    swept from the sea-bottom. Those who witnessed its progress
+    from the upper balconies of their houses, and presently saw its
+    black mass rushing close beneath their feet, looked on their
+    safety as a miracle. Many buildings were indeed washed away,
+    and in the low-lying parts of the town there was a terrible
+    loss of life. After passing far inland, the wave slowly
+    returned sea-ward, and, strangely enough, the sea, which
+    elsewhere heaved and tossed for hours after the first great
+    wave had swept over it, here came soon to rest.</p>
+
+    <p>At Callao a yet more singular instance was afforded of the
+    effect which circumstances may have upon the motion of the sea
+    after a great earthquake has disturbed it. In former
+    earthquakes Callao has suffered terribly from the effects of
+    the great sea-wave. In <span class="pagenum"><a name="page216"
+       id="page216"></a>[pg 216]</span> fact, on two occasions the
+       whole town has been destroyed, and nearly all its
+       inhabitants have been drowned, through the inrush of
+       precisely such waves as flowed into the ports of Arica and
+       Chala. But upon this occasion the centre of subterranean
+       disturbance must have been so situated that either the wave
+       was diverted from Callao, or, more probably, two waves
+       reached Callao from different sources and at different
+       times, so that the two undulations partly counteracted each
+       other. Certain it is that, although the water retreated
+       strangely from the coast near Callao, insomuch that a wide
+       tract of the sea-bottom was uncovered, there was no
+       inrushing wave comparable with those described above. The
+       sea afterward rose and fell in an irregular manner, a
+       circumstance confirming the supposition that the disturbance
+       was caused by two distinct oscillations. Six hours after the
+       occurrence of the earth-shock the double oscillations seemed
+       for a while to have worked themselves into unison, for at
+       this time three considerable waves rolled in upon the town.
+       But clearly these waves must not be compared with those
+       which in other instances had made their appearance within
+       half an hour of the earth-throes. There is little reason to
+       doubt that if the separate oscillations had re-enforced each
+       other earlier, Callao would have been completely destroyed.
+       As it was, a considerable amount of mischief was effected;
+       but the motion of the sea presently became irregular again,
+       and so continued until the morning of August 14th, when it
+       began to ebb with some regularity. But during the 14th there
+       were occasional renewals of the irregular motion, and
+       several days <span class="pagenum"><a name="page217"
+       id="page217"></a>[pg 217]</span> elapsed before the regular
+       ebb and flow of the sea were resumed.</p>
+
+    <p>Such were among the phenomena presented in the region where
+    the earthquake itself was felt. It will be seen at once that
+    within this region, or rather along that portion of the
+    sea-coast which falls within the central region of disturbance,
+    the true character of the sea-wave generated by the earthquake
+    could not be recognized. If a rock fall from a lofty cliff into
+    a comparatively shallow sea, the water around the place where
+    the rock has fallen is disturbed in an irregular manner. The
+    sea seems at one place to leap up and down; elsewhere one wave
+    seems to beat against another, and the sharpest eye can detect
+    no law in the motion of the seething waters. But presently,
+    outside the scene of disturbance, a circular wave is seen to
+    form, and if the motion of this wave be watched it is seen to
+    present the most striking contrast with the turmoil and
+    confusion at its centre. It sweeps onward and outward in a
+    regular undulation. Gradually it loses its circular figure
+    (unless the sea-bottom happens to be unusually level), showing
+    that although its motion is everywhere regular, it is not
+    everywhere equally swift. A wave of this sort, though
+    incomparably vaster, swept swiftly away on every side from the
+    scene of the great earthquake near the Peruvian Andes. It has
+    been calculated that the width of this wave varied from one
+    million to five million feet, or, roughly, from two hundred to
+    one thousand miles, while, when in mid-Pacific, the length of
+    the wave, measured along its summit in a widely-curved path
+    from one side to another of the great <span class=
+    "pagenum"><a name="page218"
+       id="page218"></a>[pg 218]</span> ocean, cannot have been
+       less than eight thousand miles.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/218.jpg"><img width="500"
+             src="images/218.jpg"
+             alt=
+           "OVER A LARGE PORTION OF ITS COURSE ITS PASSAGE WAS UNNOTED." /></a><br />
+        OVER A LARGE PORTION OF ITS COURSE ITS PASSAGE WAS UNNOTED.
+    </div>
+
+    <p>We cannot tell how deep-seated was the centre of
+    subterranean action; but there can be no doubt it was very deep
+    indeed, because otherwise the shock felt in towns separated
+    from each other by hundreds of miles could not have been so
+    nearly contemporaneous. Therefore the portion of the earth's
+    crust upheaved must have been enormous, for the length of the
+    region where the direct effects of the earthquake were
+    perceived is estimated by Professor von Hochsteter at no
+    <span class="pagenum"><a name="page219"
+       id="page219"></a>[pg 219]</span> less than two hundred and
+       forty miles. The breadth of the region is unknown, because
+       the slope of the Andes on one side and the ocean on the
+       other concealed the motion of the earth's crust.</p>
+
+    <p>The great ocean-wave swept, as we have said, in all
+    directions around the scene of the earth-throe. Over a large
+    part of its course its passage was unnoted, because in the open
+    sea the effects even of so vast an undulation could not be
+    perceived. A ship would slowly rise as the crest of the great
+    wave passed under her, and then as slowly sink again. This may
+    seem strange, at first sight, when it is remembered that in
+    reality the great sea-wave we are considering swept at the rate
+    of three or four hundred sea-miles an hour over the larger part
+    of the Pacific. But when the true character of ocean-waves is
+    understood, when it is remembered that there is no transference
+    of the water itself at this enormous rate, but simply a
+    transmission of motion (precisely as when in a high wind waves
+    sweep rapidly over a cornfield, while yet each cornstalk
+    remains fixed in the ground), it will be seen that the effects
+    of the great sea-wave could only be perceived near the shore.
+    Even there, as we shall presently see, there was much to convey
+    the impression that the land itself was rising and falling
+    rather than that the deep was moved. But among the hundreds of
+    ships which were sailing upon the Pacific when its length and
+    breadth were traversed by the great sea-wave, there was not one
+    in which any unusual motion was perceived.</p>
+
+    <p>In somewhat less than three hours after the occurrence of
+    the earthquake the ocean-wave inundated the <span class=
+    "pagenum"><a name="page220"
+       id="page220"></a>[pg 220]</span> port of Coquimbo, on the
+       Chilean seaboard, some eight hundred miles from Arica. An
+       hour or so later it had reached Constitucion, four hundred
+       and fifty miles farther south; and here for some three hours
+       the sea rose and fell with strange violence. Farther south,
+       along the shore of Chile, even to the island of Chiloe, the
+       shore-wave travelled, though with continually diminishing
+       force, owing, doubtless, to the resistance which the
+       irregularities of the shore opposed to its progress.</p>
+
+    <p>The northerly shore-wave seems to have been more
+    considerable; and a moment's study of a chart of the two
+    Americas will show that this circumstance is highly
+    significant. When we remember that the principal effects of the
+    land-shock were experienced within that angle which the
+    Peruvian Andes form with the long north-and-south line of the
+    Chilean and Bolivian Andes, we see at once that, had the centre
+    of the subterranean action been near the scene where the most
+    destructive effects were perceived, no sea-wave, or but a small
+    one, could have been sent toward the shores of North America.
+    The projecting shores of northern Peru and Ecuador could not
+    have failed to divert the sea-wave toward the west; and though
+    a reflected wave might have reached California, it would only
+    have been after a considerable interval of time, and with
+    dimensions much less than those of the sea-wave which travelled
+    southward. When we see that, on the contrary, a wave of even
+    greater proportions travelled toward the shores of North
+    America, we seem forced to the conclusion that the centre of
+    the subterranean action must have been so far to the west that
+    the sea- <span class="pagenum"><a name="page221"
+       id="page221"></a>[pg 221]</span> wave generated by it had a
+       free course to the shores of California.</p>
+
+    <p>Be this as it may, there can be no doubt that the wave which
+    swept the shores of Southern California, rising upward of sixty
+    feet above the ordinary sea-level, was absolutely the most
+    imposing of all the indirect effects of the great earthquake.
+    When we consider that even in San Pedro Bay, fully five
+    thousand miles from the centre of disturbance, a wave twice the
+    height of an ordinary house rolled in with unspeakable violence
+    only a few hours after the occurrence of the earth-throe, we
+    are most strikingly impressed with the tremendous energy of the
+    earth's movement.</p>
+
+    <p>Turning to the open ocean, let us track the great wave on
+    its course past the multitudinous islands which dot the surface
+    of the Pacific.</p>
+
+    <p>The inhabitants of the Sandwich Islands, which lie about six
+    thousand three hundred miles from Arica, might have imagined
+    themselves safe from any effects which could be produced by an
+    earthquake taking place so far away from them. But on the night
+    between August 13th and 14th, the sea around this island group
+    rose in a surprising manner, insomuch that many thought the
+    islands were sinking, and would shortly subside altogether
+    beneath the waves. Some of the smaller islands, indeed, were
+    for a time completely submerged. Before long, however, the sea
+    fell again, and as it did so the observers "found it impossible
+    to resist the impression that the islands were rising bodily
+    out of the water." For no less than three days this strange
+    oscillation of the sea continued to be experienced, the most
+    remarkable ebbs and <span class="pagenum"><a name="page222"
+       id="page222"></a>[pg 222]</span> floods being noticed at
+       Honolulu, on the island of Woahoo.</p>
+
+    <p>But the sea-wave swept onward far beyond these islands.</p>
+
+    <p>At Yokohama, in Japan, more than ten thousand five hundred
+    miles from Arica, an enormous wave poured in on August 14th,
+    but at what hour we have no satisfactory record. So far as
+    distance is concerned, this wave affords most surprising
+    evidence of the stupendous nature of the disturbance to which
+    the waters of the Pacific Ocean had been subjected. The whole
+    circumference of the earth is but twenty-five thousand miles,
+    so that this wave had travelled over a distance considerably
+    greater than two-fifths of the earth's circumference. A
+    distance which the swiftest of our ships could not traverse in
+    less than six or seven weeks had been swept over by this
+    enormous undulation in the course of a few hours.</p>
+
+    <p>More complete details reach us from the Southern
+    Pacific.</p>
+
+    <p>Shortly before midnight the Marquesas Isles and the
+    low-lying Tuamotu group were visited by the great wave, and
+    some of these islands were completely submerged by it. The
+    lonely Opara Isle, where the steamers which run between Panama
+    and New Zealand have their coaling station, was visited at
+    about half-past eleven in the evening by a billow which swept
+    away a portion of the coal depot. Afterward great waves came
+    rolling in at intervals of about twenty minutes, and several
+    days elapsed before the sea resumed its ordinary ebb and
+    flow.</p>
+
+    <p>It was not until about half-past two on the morning
+    <span class="pagenum"><a name="page223"
+       id="page223"></a>[pg 223]</span> of August 14th that the
+       Samoa Isles (sometimes called the Navigator Islands) were
+       visited by the great wave. The watchmen startled the
+       inhabitants from their sleep by the cry that the sea was
+       about to overwhelm them; and already, when the terrified
+       people rushed from their houses, the sea was found to have
+       risen far above the highest water-mark. But it presently
+       began to sink again, and then commenced a series of
+       oscillations, which lasted for several days, and were of a
+       very remarkable nature. Once in every quarter of an hour the
+       sea rose and fell, but it was noticed that it rose twice as
+       rapidly as it sank. This peculiarity is well worth
+       remarking. The eminent physicist Mallet speaks thus (we
+       follow Lyell's quotation) about the waves which traverse an
+       open sea: "The great sea-wave, advancing at the rate of
+       several miles in a minute, consists, in the deep ocean, of a
+       long, low swell of enormous volume, having an equal slope
+       before and behind, and that so gentle that it might pass
+       under a ship without being noticed. But when it reaches the
+       edge of soundings, its front slope becomes short and steep,
+       while its rear slope is long and gentle." On the shores
+       visited by such a wave, the sea would appear to rise more
+       rapidly than it sank. We have seen that this happened on the
+       shores of the Samoa group, and therefore the way in which
+       the sea rose and fell on the days following the great
+       earthquake gave significant evidence of the nature of the
+       sea-bottom in the neighborhood of these islands. As the
+       change of the great wave's figure could not have been
+       quickly communicated, we may conclude with certainty that
+       the Samoan Islands are the summits of lofty mountains, whose
+       sloping sides extend far toward the east.</p><span class=
+       "pagenum"><a name="page224"
+       id="page224"></a>[pg 224]</span>
+
+    <p>This conclusion affords interesting evidence of the
+    necessity of observing even the seemingly trifling details of
+    important phenomena.</p>
+
+    <p>The wave which visited the New Zealand Isles was altogether
+    different in character, affording a noteworthy illustration of
+    another remark of Mallet's. He says that where the sea-bottom
+    slopes in such a way that there is water of some depth close
+    inshore, the great wave may roll in and do little damage; and
+    we have seen that so it happened in the case of the Samoan
+    Islands. But he adds that, "where the shore is shelving there
+    will be first a retreat of the water, and then the wave will
+    break upon the beach and roll far in upon the land." This is
+    precisely what happened when the great wave reached the eastern
+    shores of New Zealand, which are known to shelve down to very
+    shallow water, continuing far away to sea toward the east.</p>
+
+    <p>At about half-past three on the morning of August 14th the
+    water began to retreat in a singular manner from the port of
+    Littleton, on the eastern shores of the southernmost of the New
+    Zealand Islands. At length the whole port was left entirely
+    dry, and so remained for about twenty minutes. Then the water
+    was seen returning like a wall of foam ten or twelve feet in
+    height, which rushed with a tremendous noise upon the port and
+    town. Toward five o'clock the water again retired, very slowly
+    as before, not reaching its lowest ebb until six. An hour later
+    a second huge wave inundated the port. Four times the sea
+    retired and returned with great power at intervals of about two
+    hours. Afterward the oscillation of the water was less
+    <span class="pagenum"><a name="page225"
+       id="page225"></a>[pg 225]</span> considerable, but it had
+       not wholly ceased until August 17th, and only on the 18th
+       did the regular ebb and flow of the tide recommence.</p>
+
+    <p>Around the Samoa group the water rose and fell once in every
+    fifteen minutes, while on the shores of New Zealand each
+    oscillation lasted no less than two hours. Doubtless the
+    different depths of water, the irregular conformation of the
+    island groups, and other like circumstances, were principally
+    concerned in producing these singular variations. Yet they do
+    not seem fully sufficient to account for so wide a range of
+    difference. Possibly a cause yet unnoticed may have had
+    something to do with the peculiarity. In waves of such enormous
+    extent it would be quite impossible to determine whether the
+    course of the wave motion was directed full upon a line of
+    shore or more or less obliquely. It is clear that in the former
+    case the waves would seem to follow each other more swiftly
+    than in the latter, even though there were no difference in
+    their velocity.</p>
+
+    <p>Far on beyond the shores of New Zealand the great wave
+    coursed, reaching at length the coast of Australia. At dawn of
+    August 14th Moreton Bay was visited by five well-marked waves.
+    At Newcastle, on the Hunter River, the sea rose and fell
+    several times in a remarkable manner, the oscillatory motion
+    commencing at half-past six in the morning. But the most
+    significant evidence of the extent to which the sea-wave
+    travelled in this direction was afforded at Port Fairy,
+    Belfast, South Victoria. Here the oscillation of the water was
+    distinctly perceived at midday on August 14th; and yet, to
+    reach this point, the sea-wave must <span class=
+    "pagenum"><a name="page226"
+       id="page226"></a>[pg 226]</span> not only have travelled on
+       a circuitous course nearly equal in length to half the
+       circumference of the earth, but must have passed through
+       Bass's Straits, between Australia and Van Diemen's Land, and
+       so have lost a considerable portion of its force and
+       dimensions. When w£ remember that had not the effects of the
+       earth-shock on the water been limited by the shores of South
+       America, a wave of disturbance equal in extent to that which
+       travelled westward would have swept toward the east, we see
+       that the force of the shock was sufficient to have disturbed
+       the waters of an ocean covering the whole surface of the
+       earth. For the sea-waves which reached Yokohama in one
+       direction and Port Fairy in another had each traversed a
+       distance nearly equal to half the earth's circumference; so
+       that if the surface of the earth were all sea, waves setting
+       out in opposite directions from the centre of disturbance
+       would have met each other at the antipodes of their
+       starting-point.</p>
+
+    <p>It is impossible to contemplate the effects which followed
+    the great earthquake&mdash;the passage of a sea-wave of
+    enormous volume over fully one third of the earth's surface,
+    and the force with which, on the farthermost limits of its
+    range, the wave rolled in upon shores more than ten thousand
+    miles from its starting-place&mdash;without feeling that those
+    geologists are right who deny that the subterranean forces of
+    the earth are diminishing in intensity. It may be difficult,
+    perhaps, to look on the effects which are ascribed to ancient
+    earth-throes without imagining for a while that the power of
+    modern earthquakes is altogether less. But when we consider
+    fairly the share which time had in <span class=
+    "pagenum"><a name="page227"
+       id="page227"></a>[pg 227]</span> those ancient processes of
+       change, when we see that while mountain ranges were being
+       upheaved or valleys depressed to their present position,
+       race after race, and type after type appeared on the earth,
+       and lived out the long lives which belong to races and to
+       types, we are recalled to the remembrance of the great work
+       which the earth's subterranean forces are still engaged
+       upon. Even now continents are being slowly depressed or
+       upheaved; even now mountain ranges are being raised to a new
+       level, tablelands are in process of formation, and great
+       valleys are being gradually scooped out. It may need an
+       occasional outburst, such as the earthquake of August, 1868,
+       to remind us that great forces are at work beneath the
+       earth's surface. But, in reality, the signs of change have
+       long been noted. Old shore-lines shift their place, old
+       soundings vary; the sea advances in one place and retires in
+       another; on every side Nature's plastic hand is at work
+       modelling and remodelling the earth, in order that it may
+       always be a fit abode for those who are to dwell upon
+       it.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/227.png"><img width="500"
+             src="images/227.png"
+             alt="Ship on waves." /></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="page228"
+       id="page228"></a>[pg 228]</span>
+
+    <h2>THE PHOSPHORESCENT SEA</h2>
+
+    <h4>(<span class="sc">From Studies of Animated
+    Nature.</span>)</h4>
+
+    <h3><span class="sc">By</span> W.S. DALLAS.</h3>
+    <hr class="short" />
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/228.png"><img width="200"
+             src="images/228.png"
+             alt="Small Boat and Phosphorescence." /></a>
+    </div>
+
+    <p>It is not merely on land that this phenomenon of
+    phosphorescence is to be seen in living forms. Among marine
+    animals, indeed, it is a phenomenon much more general, much
+    more splendid, and, we may add, much more familiar to those who
+    live on our coasts. There must be many in the British Isles who
+    have never had the opportunity of seeing the light of the
+    glow-worm, but there can be few of those who have frequented in
+    summer any part of our coasts, who have never seen that
+    beautiful greenish light which is then so often visible,
+    especially on our southern shores, when the water is disturbed
+    by the blade of an oar or the prow of a boat or ship. In some
+    cases, even on our own shores, the phenomenon is much more
+    brilliant, every rippling wave being crested with a line of the
+    same peculiar light, and in warmer seas exhibitions of this
+    kind are much more common. It is now <span class=
+    "pagenum"><a name="page229"
+       id="page229"></a>[pg 229]</span> known that this light is
+       due to a minute living form, to which we will afterward
+       return.</p>
+
+    <p>But before going on to speak in some detail of the organisms
+    to which the phosphorescence of the sea is due, it will be as
+    well to mention that the kind of phosphorescence just spoken of
+    is only one mode in which the phenomenon is exhibited on the
+    ocean. Though sometimes the light is shown in continuous lines
+    whenever the surface is disturbed, at other times, and,
+    according to M. de Quatrefages, more commonly, the light
+    appears only in minute sparks, which, however numerous, never
+    coalesce. "In the little channel known as the Sund de Chausez,"
+    he writes, "I have seen on a dark night each stroke of the oar
+    kindle, as it were, myriads of stars, and the wake of the craft
+    appeared in a manner besprinkled with diamonds." When such is
+    the case the phosphorescence is due to various minute animals,
+    especially crustaceans; that is, creatures which,
+    microscopically small as they are, are yet constructed more or
+    less on the type of the lobster or cray-fish.</p>
+
+    <p>At other times, again, the phosphorescence is still more
+    partial. "Great domes of pale gold with long streamers," to use
+    the eloquent words of Professor Martin Duncan, "move slowly
+    along in endless succession; small silvery disks swim, now
+    enlarging and now contracting, and here and there a green or
+    bluish gleam marks the course of a tiny, but rapidly rising and
+    sinking globe. Hour after hour the procession passes by, and
+    the fishermen hauling in their nets from the midst drag out
+    liquid light, and the soft sea jellies, crushed and torn
+    piecemeal, shine in every clinging <span class=
+    "pagenum"><a name="page230"
+       id="page230"></a>[pg 230]</span> particle. The night grows
+       dark, the wind rises and is cold, and the tide changes; so
+       does the luminosity of the sea. The pale spectres below the
+       surface sink deeper, and are lost to sight, but the
+       increasing waves are tinged here and there with green and
+       white, and often along a line, where the fresh water is
+       mixing with the salt in an estuary, there is a brightness so
+       intense that boats and shores are visible.... But if such
+       sights are to be seen on the surface, what must not be the
+       phosphorescence of the depths! Every sea-pen is glorious in
+       its light, in fact, nearly every eight-armed Alcyonarian is
+       thus resplendent, and the social Pyrosoma, bulky and a free
+       swimmer, glows like a bar of hot metal with a white and
+       green radiance."</p>
+
+    <p>Such accounts are enough to indicate how varied and how
+    general a phenomenon is the phosphorescence of the sea. To take
+    notice of one tithe of the points of interest summed up in the
+    paragraph just quoted would occupy many pages, and we must
+    therefore confine the attention to a few of the most
+    interesting facts relating to marine phosphorescence.</p>
+
+    <p>We will return to that form of marine luminosity to which we
+    first referred: what is known as the general or diffused
+    phosphorescence of the sea. From this mode of describing it the
+    reader must not infer that the surface of the ocean is ever to
+    be seen all aglow in one sheet of continuous light. So far, at
+    least, as was ever observed by M. de Quatrefages, who studied
+    this phenomenon carefully and during long periods on the coasts
+    of Brittany and elsewhere, no light was visible when the
+    surface of the sea was perfectly still. On the other hand, when
+    the sea exhibits in a high degree the <span class=
+    "pagenum"><a name="page231"
+       id="page231"></a>[pg 231]</span> phenomenon of diffused
+       phosphorescence no disturbance can be too slight to cause
+       the water to shine with that peculiar characteristic gleam.
+       Drop but a grain of sand upon its surface, and you will see
+       a point of light marking the spot where it falls, and from
+       that point as a centre a number of increasing wavelets, each
+       clearly defined by a line of light, will spread out in
+       circles all around.</p>
+
+    <p>The cause of this diffused phosphorescence was long the
+    subject of curiosity, and was long unknown, but more than a
+    hundred years ago (in 1764) the light was stated by M. Kigaut
+    to proceed from a minute and very lowly organism, now known as
+    <i>Noctiluca miliaris</i>; and subsequent researches have
+    confirmed this opinion. This Noctiluca is a spherical form of
+    not more than one-fiftieth of an inch in size, with a slight
+    depression or indentation at one point, marking the position of
+    a mouth leading to a short digestive cavity, and having close
+    beside it a filament, by means of which it probably moves
+    about. The sphere is filled with protoplasm, in which there is
+    a nucleus and one or more gaps, or "vacuoles." Such is nearly
+    all the structure that can be discerned with the aid of the
+    microscope in this simple organism.</p>
+
+    <p>Nevertheless, this lowly form is the chief cause of that
+    diffused phosphorescence which is sometimes seen over a wide
+    extent of the ocean. How innumerable the individuals belonging
+    to this species must therefore be, may be left to the
+    imagination. Probably the Noctiluca is not rivalled in this
+    respect even by miscroscopic unicellular algæ which compose the
+    "red snow."</p>
+
+    <p>By filtering sea-water containing Noctilucæ its light
+    <span class="pagenum"><a name="page232"
+       id="page232"></a>[pg 232]</span> can be concentrated, and it
+       has been found that a few teaspoonfuls will then yield light
+       enough to enable one to read holding a book at the ordinary
+       distance from the eyes&mdash;about ten inches.</p>
+
+    <p>A singular and highly remarkable case of diffused marine
+    phosphorescence was observed by Nordenskiöld during his voyage
+    to Greenland in 1883. One dark night, when the weather was calm
+    and the sea smooth, his vessel was steaming across a narrow
+    inlet called the Igaliko Fjord, when the sea was suddenly
+    observed to be illumined in the rear of the vessel by a broad
+    but sharply-defined band of light, which had a uniform,
+    somewhat golden sheen, quite unlike the ordinary bluish-green
+    phosphorescence of the sea. The latter kind of light was
+    distinctly visible at the same time in the wake of the vessel.
+    Though the steamer was going at the rate of from five to six
+    miles an hour, the remarkable sheet of light got nearer and
+    nearer. When quite close, it appeared as if the vessel were
+    sailing in a sea of fire or molten metal. In the course of an
+    hour the light passed on ahead, and ultimately it disappeared
+    in the remote horizon. The nature of this phenomenon
+    Nordenskiöld is unable to explain; and unfortunately he had not
+    the opportunity of examining it with the spectroscope.</p>
+
+    <p>If we come now to consider the more partial phosphorescence
+    of the sea, we find that it is due to animals belonging to
+    almost every group of marine forms&mdash;to Echinoderms, or
+    creatures of the sea-urchin and star-fish type, to Annelid
+    worm, to Medusidæ, or jelly-fish, as they are popularly called,
+    including the "great domes" and the "silvery disks" of the
+    <span class="pagenum"><a name="page233"
+       id="page233"></a>[pg 233]</span> passage above quoted from
+       Professor Martin Duncan, to Tunicates, among which is the
+       Pyrosoma, to Mollusks, Crustaceans, and in very many cases
+       to Actinozoa, or forms belonging to the type of the sea
+       anemone and the coral polyp.</p>
+
+    <p>Of these we will single out only a few for more special
+    notice.</p>
+
+    <p>Many of the Medusidæ, or jelly-fish, possess the character
+    of which we are speaking. In some cases the phosphorescence is
+    spontaneous among them, but in others it is not so; the
+    creature requires to be irritated or stimulated in some way
+    before it will emit the light. It is spontaneous, for example,
+    in the <i>Pelagia phosphorea</i>, but not in the allied
+    <i>Pelagia noctiluca</i>, a very common form in the
+    Mediterranean.</p>
+
+    <p>In both of the jelly-fishes just mentioned the
+    phosphorescence, when displayed at all, is on the surface of
+    the swimming disk, and this is most commonly the case with the
+    whole group. Sometimes, however, the phosphorescence is
+    specially localized. In some forms, as in <i>Thaumantius
+    pilosella</i> and other members of the same genus, it is seen
+    in buds at the base of tentacles given off from the margin of
+    the swimming-bell. In other cases it is situated in certain
+    internal organs, as in the canals which radiate from the centre
+    to the margin of the bell, or in the ovaries. It is from this
+    latter seat that the phosphorescence proceeds in <i>Oceania
+    pilata</i>, the form which gives out such a light that
+    Ehrenberg compared it to a lamp-globe lighted by a flame.</p>
+
+    <p>The property of emitting a phosphorescent light, sometimes
+    spontaneously and sometimes on being stimulated, is likewise
+    exemplified in the Ctenophora, a <span class=
+       "pagenum"><a name="page234"
+       id="page234"></a>[pg 234]</span> group resembling the
+       Medusidge in the jelly-like character of their bodies, but
+       more closely allied in structure to the Actinozoa. But we
+       will pass over these cases in order to dwell more
+       particularly on the remarkable tunicate known as Pyrosoma, a
+       name indicative of its phosphorescent property, being
+       derived from two Greek words signifying fire-body. As shown
+       in the illustration Pyrosoma is not a single creature, but
+       is composed of a whole colony of individuals, each of which
+       is represented by one of the projections on the surface of
+       the tube, closed at one end, which they all combine to form.
+       The free end on the exterior contains the mouth, while there
+       is another opening in each individual toward the interior of
+       the tube. Such colonies, which swim about by the alternate
+       contraction and dilatation of the individuals composing
+       them, are pretty common in the Mediterranean, where they may
+       attain the length of perhaps fourteen inches, with a breadth
+       of about three inches. In the ocean they may reach a much
+       greater size. Mr. Moseley, in his "Notes of a Naturalist on
+       the Challenger," mentions a giant specimen which he once
+       caught in the deep-sea trawl, a specimen four feet in length
+       and ten inches in diameter, with "walls of jelly about an
+       inch in thickness."</p>
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/234.png"><img width="250"
+             src="images/234.png"
+             alt="A. PYROSOMA. B. PONITON." /></a><br />
+        A. PYROSOMA. B. PONITON. (Magnified.)
+    </div>
+
+    <p>The same naturalist states that the light emitted by
+    <span class="pagenum"><a name="page235"
+       id="page235"></a>[pg 235]</span> this compound form is the
+       most beautiful of all kinds of phosphorescence. When
+       stimulated by a touch, or shake, or swirl of the water, it
+       "gives out a globe of bluish light, which lasts for several
+       seconds, as the animal drifts past several feet beneath the
+       surface, and then suddenly goes out." He adds that on the
+       giant specimen just referred to be wrote his name with his
+       finger as it lay on the deck in a tub at night, and in a few
+       seconds he had the gratification of seeing his name come out
+       in "letters of fire."</p>
+
+    <p>Among mollusks, the best known instance of phosphorescence
+    is in the rock-boring Pholas, the luminosity of which after
+    death is mentioned by Pliny. But it is not merely after death
+    that Pholas becomes luminous&mdash;a phenomenon perfectly
+    familiar even in the case of many fish, especially the herring
+    and mackerel. It was long before the luminosity of the living
+    animal was known, but this is now a well-ascertained fact; and
+    Panceri, an Italian naturalist, recently dead, has been able to
+    discover in this, as in several other marine phosphorescent
+    forms, the precise seat of the light-giving bodies, which he
+    has dissected out again and again for the sake of making
+    experiments in connection with this subject.</p>
+
+    <p>A more beautiful example of a phosphorescent mollusk is
+    presented by a sea-slug called <i>Phyllirhoë bucephala</i>.
+    This is a creature of from one and a half to two inches in
+    length, without a shell in the adult stage, and without even
+    gills. It breathes only by the general surface of the body. It
+    is common enough in the Mediterranean, but is not easy to see,
+    as it is almost perfectly transparent, so that it cannot be
+    distinguished <span class="pagenum"><a name="page236"
+       id="page236"></a>[pg 236]</span> without difficulty, by day
+       at least, from the medium in which it swims. By night,
+       however, it is more easily discerned, in consequence of its
+       property of emitting light. When disturbed or stimulated in
+       any way, it exhibits a number of luminous spots of different
+       sizes irregularly distributed all over it, but most thickly
+       aggregated on the upper and under parts. These
+       phosphorescent spots, it is found, are not on the surface,
+       but for the most part represent so many large cells which
+       form the terminations of nerves, and are situated underneath
+       the transparent cuticle. The spots shine with exceptional
+       brilliancy when the animal is withdrawn from the water and
+       stimulated by a drop of ammonia.</p>
+
+    <p>Among the Annelid worms a species of <i>Nereis</i>, or
+    sea-centipedes, has earned by its phosphorescent property the
+    specific name of <i>noctiluca</i> (night-shining), and the same
+    property is very beautifully shown in <i>Polynoë</i>, a near
+    ally of the familiar sea-mouse. M. de Quatrefages speaks with
+    enthusiasm of the beauty of the spectacle presented by this
+    latter form when examined under a microscope magnifying to the
+    extent of a hundred diameters. He then found, as he did in the
+    great majority of cases which he studied, that the
+    phosphorescence was confined to the motor muscles, and was
+    manifested solely when these were in the act of contracting,
+    manifested, too, not in continuous lines along the course of
+    the muscles, but in rows of brilliant points.</p>
+
+    <p>More interesting than the Annelids, however, are the
+    Alcyonarian Actinozoa. The Actinozoa have already been
+    described as formed on the type of the sea-anemone and the
+    coral polyp, that is, they are all animals with a radiate
+    structure, attached to one end, and <span class=
+    "pagenum"><a name="page237"
+       id="page237"></a>[pg 237]</span> having their only opening
+       at the other end, which is surrounded by tentacles. In the
+       Alcyonarian forms belonging to this great group these
+       tentacles are always eight in number, and fringed on both
+       sides. Moreover, these forms are almost without exception
+       compound. Like the Pyrosoma, they have a common life
+       belonging to a whole stock or colony, as well as an
+       individual life.</p>
+
+    <p>Now, throughout this sub-division of the Actinozoa
+    phosphorescence is a very general phenomenon. Professor
+    Moseley, already quoted as a naturalist accompanying the
+    Challenger expedition, informs us that "all the Alcyonarians
+    dredged by the Challenger in deep water were found to be
+    brilliantly phosphorescent when brought to the surface."</p>
+
+    <p>Among these Alcyonarians are the sea-pens mentioned in the
+    quotation above made from Professor Martin Duncan. Each sea-pen
+    is a colony of Alcyonarians, and the name is due to the
+    singular arrangement of the individuals upon the common stem.
+    This stem is supported internally by a coral rod, but its outer
+    part is composed of fleshy matter belonging to the whole
+    colony. The lower portion of it is fixed in the muddy bottom of
+    the sea, but the upper portion is free, and gives off a number
+    of branches, on which the individual polyps are seated. The
+    whole colony thus has the appearance of a highly ornamental
+    pen.</p>
+
+    <p>There is one British species, <i>Pennatula phosphorea</i>,
+    which is found in tolerably deep water, and is from two to four
+    inches in length. The specific name again indicates the
+    phosphorescent quality belonging to it. When irritated, it
+    shines brilliantly, and the curious thing is that the
+    phosphorescence travels gradually on from <span class=
+    "pagenum"><a name="page238"
+       id="page238"></a>[pg 238]</span> polyp to polyp, starting
+       from the point at which the irritation is applied. If the
+       lower part of the stem is irritated, the phosphorescence
+       passes gradually upwards along each pair of branches in
+       succession; but if the top is irritated the phosphorescence
+       will pass in the same way downwards. When both top and
+       bottom are irritated simultaneously two luminous currents
+       start at once, and, meeting in the middle, usually become
+       extinguished there; but on one occasion Panceri found that
+       the two crossed, and each completed its course independently
+       of the other. Those of our readers who have had
+       opportunities of making or seeing experiments with the
+       sensitive plant (<i>Mimosa pudica</i>) will be reminded of
+       the way in which, when that plant is irritated, the
+       influence travels regularly on from pinnules to pinnules and
+       pinnae to pinnae.</p>
+
+    <p>In all the cases mentioned the phenomenon of phosphorescence
+    is exhibited by invertebrate animals; but though rare, it is
+    not an unknown phenomenon even in living vertebrates. In a
+    genus of deep-sea fishes called Stomias, Gunther mentions that
+    a "series of phosphorescent dots run along the lower side of
+    the head, body, and tail." Several other deep-sea fishes,
+    locally phosphorescent, seem to have been dredged up by the
+    French ship Talisman in its exploring cruise off the west coast
+    of Northern Africa in 1883. During the same expedition, a
+    number of deep-sea phosphorescent crustaceans were dredged up,
+    the phosphorescence being in some cases diffused over the whole
+    body, in other cases localized to particular areas. In deep-sea
+    forms the phenomenon is, in fact, so common, as to have given
+    rise to the theory that in the depths of the ocean, where the
+    light <span class="pagenum"><a name="page239"
+       id="page239"></a>[pg 239]</span> of the sun cannot
+       penetrate, the phosphorescence of various organisms diffuse
+       a light which limits the domain of absolute darkness.</p>
+
+    <p>So much by way of illustration regarding the phosphorescence
+    exhibited by animals, terrestrial and marine; but it ought to
+    be noticed that there are also a few cases in which the same
+    phenomenon is to be witnessed in plants. These are not so
+    numerous as was at one time supposed, the property having been
+    mistakenly ascribed to some plants not really luminous.</p>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/239.png"><img width="600"
+             src="images/239.png"
+             alt="A PHOSPHORESCENT SEA." /></a><br />
+        A PHOSPHORESCENT SEA.
+    </div>
+
+    <p>In some instances the mistake appears to have been due to a
+    subjective effect produced by brilliantly colored (red or
+    orange) flowers, such as the great Indian cress, the orange
+    lily, the sunflower, and the marigold. The fact that such
+    flowers do give out in the dusk sudden flashes of light has
+    often been stated on the authority of a daughter of Linnæus,
+    subsequently <span class="pagenum"><a name="page240"
+       id="page240"></a>[pg 240]</span> backed by the assertions of
+       various other observers. But most careful observers seem to
+       be agreed that the supposed flashes of light are in reality
+       nothing else than a certain dazzling of the eyes.</p>
+
+    <p>In another case, in which a moss, <i>Schistostega
+    osmundacea</i>, has been stated to be phosphorescent, the
+    effect is said to be really due to the refraction and
+    reflection of light by minute crystals scattered over its
+    highly cellular leaves, and not to be produced at all where the
+    darkness is complete.</p>
+
+    <p>Among plants, genuine phosphorescence is to be found chiefly
+    in certain fungi, the most remarkable of which is
+    <i>Rhizomorpha subterranea</i>, which is sometimes to be seen
+    ramifying over the walls of dark, damp mines, caverns, or
+    decayed towers, and emitting at numerous points a mild
+    phosphorescent light, which is sometimes bright enough to allow
+    of surrounding objects being distinguished by it. The name of
+    "vegetable glow-worm" has sometimes been applied to this
+    curious growth.</p>
+
+    <p>Among other phosphorescent fungi are several species of
+    Agaricus, including the <i>A. olearius</i> of Europe, <i>A.
+    Gardneri</i> of Brazil, and <i>A. lampas</i> of Australia, and
+    besides the members of this genus, <i>Thelaphora cærulea</i>,
+    which is the cause of the phosphorescent light sometimes to be
+    seen on decaying wood&mdash;the "touchwood" which many boys
+    have kept in the hope of seeing this light displayed. The milky
+    juice of a South American Euphorbia (<i>E. phosphorea</i>) is
+    stated by Martins to be phosphorescent when gently heated. But
+    phosphorescence is evidently not so interesting and important a
+    phenomenon in the vegetable as it is in the animal
+    kingdom.</p><span class="pagenum"><a name="page241"
+       id="page241"></a>[pg 241]</span>
+
+    <p>The whole phenomenon is one that gives rise to a good many
+    questions which it is not easy to answer, and this is
+    especially true in the case of animal phosphorescence. What is
+    the nature of the light? What are the conditions under which it
+    is manifested? What purpose does it serve in the animal
+    economy?</p>
+
+    <p>As to the nature of the light, the principal question is
+    whether it is a direct consequence of the vital activity of the
+    organism in which it is seen, of such a nature that no further
+    explanation can be given of it, any more than we can explain
+    why a muscle is contracted under the influence of a
+    nerve-stimulus; or whether it is due to some chemical process
+    more or less analogous to the burning of a candle.</p>
+
+    <p>The fact of luminosity appearing to be in certain cases
+    directly under the control of the creature in which it is
+    found, and the fact of its being manifested in many forms, as
+    M. de Quatrefages found, only when muscular contraction was
+    taking place, would seem to favor the former view. On the other
+    hand, it is against this view that the phosphorescence is often
+    found to persist after the animal is dead, and even in the
+    phosphorescent organs for a considerable time after they have
+    been extracted from the body of the animal. In the glow-worm
+    the light goes on shining for some time after the death of the
+    insect, and even when it has become completely extinguished it
+    can be restored for a time by the application of a little
+    moisture. Further, both Matteucci and Phipson found that when
+    the luminous substance was extracted from the insect it would
+    keep on glowing for thirty or forty minutes.</p>
+
+    <p>In Pholas the light is still more persistent, and it is
+    <span class="pagenum"><a name="page242"
+       id="page242"></a>[pg 242]</span> found that when the dead
+       body of this mollusk is placed in honey, it will retain for
+       more than a year the power of emitting light when plunged in
+       warm water.</p>
+
+    <p>The investigations of recent years have rendered it more and
+    more probable that the light exhibited by phosphorescent
+    organisms is due to a chemical process somewhat analogous to
+    that which goes on in the burning of a candle. This latter
+    process is one of rapid oxidation. The particles of carbon
+    supplied by the oily matter that feeds the candle become so
+    rapidly combined with oxygen derived from the air that a
+    considerable amount of light, along with heat, is produced
+    thereby. Now, the phenomenon of phosphorescence in organic
+    forms, whether living or dead, appears also to be due to a
+    process of oxidation, but one that goes on much more slowly
+    than in the case of a lighted candle. It is thus more closely
+    analogous to what is observed in the element phosphorus itself,
+    which owes its name (meaning "light-bearer") to the fact that
+    when exposed to the air at ordinary temperatures it glows in
+    the dark, in consequence of its becoming slowly combined with
+    oxygen.</p>
+
+    <p>At one time it was believed that the presence of oxygen was
+    not necessary to the exhibition of phosphorescence in organic
+    forms, but it has now been placed beyond doubt that this is a
+    mistake. Oxygen has been proved to be indispensable, and hence
+    we see a reason for the luminous organs in the glow-worm being
+    so intimately connected, as above mentioned, with the air-tubes
+    that ramify through the insect.</p>
+
+    <p>This fact of itself might be taken as a strong indication of
+    the chemical nature of the process to which <span class=
+    "pagenum"><a name="page243"
+       id="page243"></a>[pg 243]</span> phosphorescence is due. But
+       the problem has been made the subject of further
+       investigations which have thrown more light upon it. It was
+       long known that there were various inorganic bodies besides
+       phosphorus which emitted a phosphorescent light in the dark,
+       at least after being exposed to the rays of the sun; but it
+       was not till quite recently that any organic compound was
+       known to phosphoresce at ordinary temperatures.</p>
+
+    <p>This discovery was made by a Polish chemist, named
+    Bronislaus Radziszewski, who followed it up with a long series
+    of experiments on the phosphorescence of organic compounds, by
+    which he was able to determine the conditions under which that
+    phenomenon was exhibited. In all the substances investigated by
+    him in which phosphorescence was introduced he found that three
+    conditions were essential to its production: (1) that oxygen
+    should be present; (2) that there should be an alkaline
+    reaction in the phosphorescing mixture&mdash;that is, a
+    reaction such as is produced on acids and vegetable coloring
+    matters by potash, soda, and the other alkalies; and (3) that
+    some kind of chemical action should take place.</p>
+
+    <p>He found, moreover, that among the organic compounds that
+    could be made to phosphoresce under these conditions were
+    nearly all the fixed and ethereal oils. With reference to the
+    phosphorescence of animals, this observation is important, for
+    it has been shown in a great many cases that a fatty substance
+    forms the main constituent in their luminous organs. This has
+    long been known to be the case in the luminous insects
+    belonging to the Lampyridæ and Elateridæ, as well as
+    <span class="pagenum"><a name="page244"
+       id="page244"></a>[pg 244]</span> in the luminous centipedes;
+       and the researches of Panceri, already referred to, on the
+       luminous organs of many marine forms have shown that it
+       holds good with regard to these also.</p>
+
+    <p>We may, therefore, conclude that substances fitted to
+    phosphoresce under the conditions determined by the experiments
+    of Radziszewski are generally, and probably universally,
+    present in the luminous organs of phosphorescent animals. Now,
+    what is to be said as to the occurrence of these conditions?
+    The access of oxygen is in all cases easy to account for, but
+    it must also be shown how the alkaline reaction is to be
+    produced. We need not expect to find in animal organisms
+    potash, soda, ammonia, and the other common alkalies; but it
+    was established by experiment that the alkaline organic
+    compounds cholin and neurin, which are present in animal
+    tissues, would also serve to bring about the phenomenon of
+    phosphorescence in the substances on which the experiments were
+    made.</p>
+
+    <p>Accordingly, it seems fair to conclude that when all these
+    conditions for the production of phosphorescence in a chemical
+    laboratory are present in animal organisms, the phenomenon,
+    when observed in these, is exactly of the same nature as that
+    which is produced artificially. By that it is meant that animal
+    phosphorescence is attended, like the artificial phenomenon, by
+    a slow chemical action, or in other words, that the
+    phosphorescent light is due to a gradual process of
+    oxidation.</p>
+
+    <p>One curious circumstance has been discovered which lends
+    still further probability to this explanation. It was mentioned
+    above that among phosphorescent plants <span class=
+    "pagenum"><a name="page245"
+       id="page245"></a>[pg 245]</span> there are several species
+       of Agaricus. Now, from one species of this genus, though not
+       indeed one of the phosphorescent species (from <i>A.
+       muscarius</i>) there has been extracted a principle called
+       <i>amanitia</i>, which is found to be identical with cholin.
+       In the light of the results derived from the investigations
+       just referred to it is reasonable to draw the conclusion
+       that, if sought for, this principle would likewise be found
+       in the phosphorescent species in which the other conditions
+       of phosphorescence are also present.</p>
+
+    <p>On this theory of the production of the phenomenon now under
+    consideration, the effect of shaking or of vital action in
+    giving rise to or intensifying the exhibition of the light is
+    accounted for by the fact that by these means fresh supplies of
+    oxygen are brought into contact with the phosphorescent
+    substance. The effect of ammonia on the light emitted by the
+    sea-slug <i>Phyllirhoë bucephala</i>, is also fully explained,
+    ammonia being one of those alkaline substances which are so
+    directly favorable to the exhibition of the phenomenon.</p>
+
+    <p>Nor is it difficult to account for the control which in some
+    cases insects appear to have over the luminosity of the
+    phosphorescent organs, exhibiting and withdrawing the light at
+    will. It is not necessary to suppose that this is an immediate
+    effect, a conversion of nerve force into light, and a
+    withdrawal of that force. The action of the creature's will may
+    be merely in maintaining or destroying the conditions under
+    which the light is manifested. It may, for example, have the
+    power of withdrawing the supply of oxygen, and this supposition
+    receives some countenance from the observation cited from Kirby
+    and Spence on the two <span class="pagenum"><a name="page246"
+       id="page246"></a>[pg 246]</span> captured glow-worms, one of
+       which withdrew its light, while the other kept it shining,
+       but while doing so had the posterior extremity of the
+       abdomen in constant motion. But the animal may also have the
+       power in another way of affecting the chemical conditions of
+       the phenomenon. It may, for example, have the power of
+       increasing or diminishing by some nervous influence the
+       supply of the necessary alkaline ingredient.</p>
+
+    <p>But if animal phosphorescence is really due to a process of
+    slow oxidation, there is one singular circumstance to be noted
+    in connection with it. Oxidation is a process that is normally
+    accompanied by the development of heat. Even where no light is
+    produced an increase of temperature regularly takes place when
+    substances are oxidized. We ought, then, to expect such a rise
+    of temperature when light is emitted by the phosphorescent
+    organs of animals. But the most careful observations have shown
+    that nothing of the kind can be detected. It was with a view to
+    test this that Panceri dissected out the luminous organs of so
+    many specimens of Pholas. He selected this mollusk because it
+    was so abundant in the neighborhood of Naples, where, his
+    experiments were made; and in making his experiments he made
+    use of a thermopile, an apparatus by which, with the aid of
+    electricity, much smaller quantities of heat can be indicated
+    than by means of the most delicate thermometer. The organs
+    remained luminous long after they were extracted, but no rise
+    in temperature whatever could be found to accompany the
+    luminosity. Many experiments upon different animals were made
+    with similar negative results by means of the
+    thermometer.</p><span class="pagenum"><a name="page247"
+       id="page247"></a>[pg 247]</span>
+
+    <p>The only explanation of this that can be given is probably
+    to be found in the fact that the chemical process ascertained
+    to go on in the phosphorescence of organic compounds on which
+    experiments were made in the laboratory is an extremely slow
+    one.</p>
+
+    <p>The so-called phosphorescence of most inorganic bodies is
+    one of a totally different nature from that exhibited in
+    organic forms. The diamond shines for a time in the dark after
+    it has been exposed to the sun; so do pieces of quartz when
+    rubbed together, and powdered fluor-spar when heated shines
+    with considerable brilliancy. Various artificial compounds,
+    such as sulphide of calcium (Canton's phosphorus, as it is
+    called from the discoverer), sulphate of barium (Bologna stone,
+    or Bologna phosphorus), sulphide of strontium, etc., after
+    being illuminated by the rays of the sun, give out in the dark
+    a beautiful phosphorescence, green, blue, violet, orange, red,
+    according to circumstances. The luminous paint which has
+    recently attracted so much attention is of the same nature. In
+    these cases what we have is either a conversion of heat rays
+    into light rays (as in the powdered fluor-spar), or the
+    absorption and giving out again of sun-rays. In the latter case
+    the phenomenon is essentially the same as fluorescence, in
+    which the dark rays of the solar spectrum beyond the violet are
+    made visible.</p>
+
+    <p>But we must now return to the other questions that have been
+    started in relation to phosphorescence in animals. There has
+    been much speculation as to the object of this light, and to
+    the purposes it serves in Nature. Probably no general answer
+    can be given to this question. It is no doubt impossible to
+    show why so many <span class="pagenum"><a name="page248"
+       id="page248"></a>[pg 248]</span> animals have been endowed
+       with this remarkable property; but we may consider some of
+       the effects which the possession of it has in different
+       cases.</p>
+
+    <p>In the first place, it will undoubtedly serve in many cases
+    to afford light to enable the animal to see by, and in the
+    Lampyridæ it would seem that the degree of luminosity is
+    related to the development of the vision. In that family,
+    according to the Rev. H.S. Gorham, the eyes are developed, as a
+    rule, in inverse proportion to the luminosity. Where there is
+    an ample supply of this kind of light the eyes are small, but
+    where the light is insignificant the eyes are large by way of
+    compensation. And moreover, where both eyes and light are
+    small, then the antennae are large and feathery, so that the
+    deficiency in the sense of sight is made up for by an unusual
+    development in the organs of touch.</p>
+
+    <p>But it is none the less certain that the presence of this
+    light cannot always be designed to serve this purpose, for many
+    of the animals so endowed are blind. The phosphorescent
+    centipedes are without eyes, like all the other members of the
+    genus (<i>Geophilus</i>) to which they belong, and probably the
+    majority of phosphorescent marine forms are likewise destitute
+    of organs of sight.</p>
+
+    <p>Another suggestion is that the light derived from these
+    marine forms, and especially from deep-sea Alcyonarians, is
+    what enables the members of the deep-sea fauna that are
+    possessed of eyes (which are always enormously enlarged) to
+    see. Such is the suggestion of Dr. Carpenter, Sir Wyville
+    Thomson, and Mr. Gwyn Jeffries; and it is possible that this
+    actually is one of the effects of the phosphorescent property.
+    But if so, it <span class="pagenum"><a name="page249"
+       id="page249"></a>[pg 249]</span> remains to inquire how the
+       forms endowed with it came to be possessed of a power useful
+       in that way to other forms, but not to themselves. According
+       to the Darwinian doctrine of development, the powers that
+       are developed in different organisms by the process of
+       natural selection are such as are useful to themselves and
+       not to others, unless incidentally.</p>
+
+    <p>This consideration has led to another suggestion, namely,
+    that the property of phosphorescence serves as a protection to
+    the forms possessing it, driving away enemies in one way or
+    another: it may be by warning them of the fact that they are
+    unpalatable food, as is believed to be the case with the colors
+    of certain brilliantly-colored caterpillars; it may be in other
+    ways. In Kirby and Spence one case is recorded in which the
+    phosphorescence of the common phosphorescent centipede
+    (<i>Geophilus electricus</i>) was actually seen apparently to
+    serve as a means of defence against an enemy. "Mr. Shepherd,"
+    says that authority, "once noticed a scarabeus running round
+    the last-mentioned insect when shining, as if wishing, but
+    afraid to attack it." In the case of the jelly-fishes, it has
+    been pointed out that their well-known urticating or stinging
+    powers would make them at least unpleasant, if not dangerous,
+    food for fishes; and that consequently the luminosity by which
+    so many of them are characterized at night may serve at once as
+    a warning to predatory fishes and as a protection to
+    themselves. The experience of the unpleasant properties of many
+    phosphorescent animals may likewise have taught fishes to avoid
+    all forms possessing this attribute, even though many of them
+    might be quite harmless.</p><span class="pagenum"><a name=
+    "page250"
+       id="page250"></a>[pg 250]</span>
+
+    <p>Lastly, it has been suggested that the phosphorescence in
+    the female glow-worm may be designed to attract the male; and
+    that it will actually have this effect may readily be taken for
+    granted. Observation shows that the male glow-worm is very apt
+    to be attracted by a light. Gilbert White of Selborne mentions
+    that they, attracted by the light of the candles, came into his
+    parlor. Another observer states that by the same light he
+    captured as many as forty male glow-worms in one night.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/250.png"><img width="500"
+             src="images/250.png"
+             alt="glow-worms by candlelight" /></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="page251"
+       id="page251"></a>[pg 251]</span>
+
+    <h2>COMETS</h2>
+
+    <h4>(<span class="sc">From Marvels of the Heavens</span>.)</h4>
+
+    <h3><span class="sc">By</span> CAMILLE FLAMMARION.</h3>
+    <hr class="short" />
+
+    <div class="poem">
+        <div class="stanza">
+            <p>"Je viens vous annoncer une grande nouvelle:</p>
+
+            <p>Nous l'avons, en dormant, madame, échappé belle.</p>
+
+            <p>Un monde près de nous a passé tout du long,</p>
+
+            <p>Est chu tout au travers de notre tourbillon;</p>
+
+            <p>Et s'il eût en chemin rencontré notre terre,</p>
+
+            <p>Elle eût été brisée en morceaux comme verre."</p>
+
+            <p class="i30"><span class="sc">Molière</span>.</p>
+        </div>
+    </div>
+
+    <div class="figleft"
+         style="width:225px;">
+        <a href="images/251.png"><img width="225"
+             src="images/251.png"
+             alt="comet" /></a>
+    </div>
+
+    <p>This announcement of Trissontin's to Philaminte, who begins
+    the parody on the fears caused by the appearance of comets,
+    would not have been a parody four or five centuries ago. These
+    tailed bodies, which suddenly come to light up the heavens,
+    were for long regarded with terror, like so many warning signs
+    of divine wrath. Men have always thought themselves much more
+    important than they really are in the universal order; they
+    have had the vanity to pretend that the whole creation was made
+    for them, whilst in reality the whole creation does not suspect
+    their existence. The Earth we inhabit is only one of the
+    smallest <span class="pagenum"><a name="page252"
+       id="page252"></a>[pg 252]</span> worlds; and therefore it
+       can scarcely be for it alone that all the wonders of the
+       heavens, of which the immense majority remains hidden from
+       it, were created. In this disposition of man to see in
+       himself the centre and the end of everything, it was easy
+       indeed to consider the steps of nature as unfolded in his
+       favor; and if some unusual phenomenon presented itself, it
+       was considered to be without doubt a warning from Heaven. If
+       these illusions had had no other result than the
+       amelioration of the more timorous of the community one would
+       regret these ages of ignorance; but not only were these
+       fancied warnings of no use, seeing that once the danger
+       passed, man returned to his former state; but they also kept
+       up among people imaginary terrors, and revived the fatal
+       resolutions caused by the fear of the end of the world.</p>
+
+    <p>When one fancies the world is about to end,&mdash;and this
+    has been believed for more than a thousand years,&mdash;no
+    solicitude is felt in the work of improving this world; and, by
+    the indifference or disdain into which one falls, periods of
+    famine and general misery are induced which at certain times
+    have overtaken our community. Why use the wealth of a world
+    which is going to perish? Why work, be instructed, or rise in
+    the progress of the sciences or arts? Much better to forget the
+    world, and absorb one's self in the barren contemplation of an
+    unknown life. It is thus that ages of ignorance weigh on man,
+    and thrust him further and further into darkness, while Science
+    makes known by its influence on the whole community, its great
+    value, and the magnitude of its aim.</p>
+
+    <p>The history of a comet would be an instructive
+          <span class="pagenum"><a name="page253"
+       id="page253"></a>[pg 253]</span> episode of the great
+       history of the heavens. In it could be brought together the
+       description of the progressive movement of human thought, as
+       well as the astronomical theory of these extraordinary
+       bodies. Let us take, for example, one of the most memorable
+       and best-known comets, and give an outline of its successive
+       passages near the Earth. Like the planetary worlds, Comets
+       belong to the solar system, and are subject to the rule of
+       the Star King. It is the universal law of gravitation which
+       guides their path; solar attraction governs them, as it
+       governs the movement of the planets and the small
+       satellites. The chief point of difference between them and
+       the planets is, that their orbits are very elongated; and,
+       instead of being nearly circular, they take the elliptical
+       form. In consequence of the nature of these orbits, the same
+       comet may approach very near the Sun, and afterwards travel
+       from it to immense distances. Thus, the period of the Comet
+       of 1680 has been estimated at three thousand years. It
+       approaches the Sun, so as to be nearer to it than our Moon
+       is to us, whilst it recedes to a distance 853 times greater
+       than the distance of the Earth from the Sun. On the 17th of
+       December, 1680, it was at its perihelion&mdash;that is, at
+       its greatest proximity to the Sun; it is now continuing its
+       path beyond the Neptunian orbit. Its velocity varies
+       according to its distance from the solar body. At its
+       perihelion it travels thousands of leagues per minute; at
+       its aphelion it does not pass over more than a few yards.
+       Its proximity to the Sun in its passage near that body
+       caused Newton to think that it received a heat twenty-eight
+       thousand times greater than that we experience at the summer
+       <span class="pagenum"><a name="page254"
+       id="page254"></a>[pg 254]</span> solstice; and that this
+       heat being two thousand times greater than that of red-hot
+       iron, an iron globe of the same dimensions would be fifty
+       thousand years entirely losing its heat. Newton added that
+       in the end comets will approach so near the Sun that they
+       will not be able to escape the preponderance of its
+       attraction, and that they will fall one after the other into
+       this brilliant body, thus keeping up the heat which it
+       perpetually pours out into space. Such is the deplorable end
+       assigned to comets by the author of the "Principia," an end
+       which makes De la Brétonne say to Rétif: "An immense comet,
+       already larger than Jupiter, was again increased in its path
+       by being blended with six other dying comets. Thus displaced
+       from its ordinary route by these slight shocks, it did not
+       pursue its true elliptical orbit; so that the unfortunate
+       thing was precipitated into the devouring centre of the
+       Sun." "It is said," added he, "that the poor comet, thus
+       burned alive, sent forth dreadful cries!"</p>
+
+    <div class="figcenter"
+         style="width:300px;">
+        <a href="images/281.jpg"><img width="300"
+             src="images/281sm.jpg"
+             alt="A COMET" /></a><br />
+        A COMET
+    </div>
+
+    <p>It will be interesting, then, in a double point of view, to
+    follow a comet in its different passages in sight of the Earth.
+    Let us take the most important in astronomical
+    history&mdash;the one whose orbit has been calculated by Edmund
+    Halley, and which was named after him. It was in 1682 that this
+    comet appeared in its greatest brilliancy, accompanied with a
+    tail which did not measure less than thirty-two millions of
+    miles. By the observation of the path which it described in the
+    heavens, and the time it occupied in describing it, this
+    astronomer calculated its orbit, and recognized that the comet
+    was the same as that which was admired in 1531 and 1607, and
+    which ought to have reappeared in <span class=
+       "pagenum"><a name="page255"
+       id="page255"></a>[pg 255]</span> 1759. Never did scientific
+       prediction excite a more lively interest. The comet returned
+       at the appointed time; and on the 12th of March, 1759,
+       reached its perihelion. Since the year 12 before the
+       Christian era, it had presented itself twenty-four times to
+       the Earth. It was principally from the astronomical annals
+       of China that it was possible to follow it up to this
+       period.</p>
+
+    <p>Its first memorable appearance in the history of France is
+    that of 837, in the reign of Louis le Débonnaire. An anonymous
+    writer of chronicles of that time, named "The Astronomer," gave
+    the following details of this appearance, relative to the
+    influence of the comet on the imperial imagination:</p>
+
+    <p>"During the holy days of the solemnization of Easter, a
+    phenomenon ever fatal, and of gloomy foreboding, appeared in
+    the heavens. As soon as the Emperor, who paid attention to
+    these phenomena, received the first announcement of it, he gave
+    himself no rest until he had called a certain learned man and
+    myself before him. As soon as I arrived, he anxiously asked me
+    what I thought of such a sign; I asked time of him, in order to
+    consider the aspects of the stars, and to discover the truth by
+    their means, promising to acquaint him on the morrow; but the
+    Emperor, persuaded that I wished to gain time, which was true,
+    in order not to be obliged to announce anything fatal to him,
+    said to me: 'Go on the terrace of the palace and return at once
+    to tell me what you have seen, for I did not see this star last
+    evening, and you did not point it out to me; but I know that it
+    is a comet; tell me what you think it announces to me.' Then
+    scarcely <span class="pagenum"><a name="page256"
+       id="page256"></a>[pg 256]</span> allowing me time to say a
+       word, he added: 'There is still another thing you keep back;
+       it is that a change of reign and the death of a prince are
+       announced by this sign.' And as I advanced the testimony of
+       the prophet, who said: 'Fear not the signs of the heavens as
+       the nations fear them,' the prince with his grand nature,
+       and the wisdom which never forsook him, said, 'We must not
+       only fear Him who has created both us and this star. But as
+       this phenomenon may refer to us, let us acknowledge it as a
+       warning from Heaven."</p>
+
+    <p>Louis le Débonnaire gave himself and his court to fasting
+    and prayer, and built churches and monasteries. He died three
+    years later, in 840, and historians have profited by this
+    slight coincidence to prove that the appearance of the comet
+    was a harbinger of death. The historian, Raoul Glader, added
+    later: "These phenomena of the universe are never presented to
+    man without surely announcing some wonderful and terrible
+    event."</p>
+
+    <p>Halley's comet again appeared in April, 1066, at the moment
+    when William the Conqueror invaded England. It was pretended
+    that it had the greatest influence on the fate of the battle of
+    Hastings, which delivered over the country to the Normans.</p>
+
+    <p>A contemporary poet, alluding probably to the English diadem
+    with which William was crowned, had proclaimed in one place,
+    "that the comet had been more favorable to William than nature
+    had been to Caesar; the latter had no hair, but William had
+    received some from the comet." A monk of Malmesbury
+    apostrophized the comet in these terms: "Here thou art again,
+    thou cause of the tears of many <span class=
+       "pagenum"><a name="page257"
+       id="page257"></a>[pg 257]</span> mothers! It is long since I
+       have seen thee, but I see thee now, more terrible than ever;
+       thou threatenest my country with complete ruin!"</p>
+
+    <p>In 1455, the same comet made a more memorable appearance
+    still. The Turks and Christians were at war, the West and the
+    East seemed armed from head to foot&mdash;on the point of
+    annihilating each other. The crusade undertaken by Pope
+    Calixtus III. against the invading Saracens, was waged with
+    redoubled ardor on the sudden appearance of the star with the
+    flaming tail. Mahomet II. took Constantinople by storm, and
+    raised the siege of Belgrade. But the Pope having put aside
+    both the curse of the comet, and the abominable designs of the
+    Mussulmans, the Christians gained the battle, and vanquished
+    their enemies in a bloody fight. The <i>Angelus</i> to the
+    sound of bells dates from these ordinances of Calixtus III.
+    referring to the comet.</p>
+
+    <p>In his poem on astronomy, Daru, of the French Academy,
+    describes this episode in eloquent terms:</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p class="i2">"Un autre Mahomet a-t-il d'un bras
+            puissant</p>
+
+            <p class="i2">Aux murs de Constantine arboré le
+            croissant:</p>
+
+            <p class="i2">Le Danube étonné se trouble au bruit des
+            armes,</p>
+
+            <p class="i2">La Grèce est dans les fers, l'Europe est
+            en alarmes;</p>
+
+            <p class="i2">Et pour comble d'horreur, l'astre au
+            visage ardent</p>
+
+            <p class="i2">De ses ailes de feu va couvrir
+            l'Occident.</p>
+
+            <p class="i2">Au pied de ses autels, qu'il ne saurait
+            défendre,</p>
+
+            <p class="i2">Calixte, l'oeil en pleurs, le front
+            convert de cendre,</p>
+
+            <p class="i2">Conjure la comète, objet de tant
+            d'effroi:</p>
+
+            <p class="i2">Regarde vers les cieux, pontife, et
+            lève-toi!</p>
+
+            <p class="i2">L'astre poursuit sa course, et le fer
+            d'Huniade</p>
+
+            <p class="i2">Arrête le vainqueur, qui tombe sous
+            Belgrade.</p>
+
+            <p class="i2">Dans les cieux cependant le globe
+            suspendu,</p>
+
+            <p class="i2">Par la loi générale à jamais
+            retenu,</p><span class="pagenum"><a name="page258"
+               id="page258"></a>[pg 258]</span>
+
+            <p class="i2">Ignore les terreurs, l'existence de
+            Rome,</p>
+
+            <p class="i2">Et la Terre peut-être, et jusqu'au nom de
+            l'homme,</p>
+
+            <p class="i2">De l'homme, être crédule, atome
+            ambitieux,</p>
+
+            <p class="i2">Qui tremble sous un prêtre et qui lit
+            dans les cieux."</p>
+        </div>
+    </div>
+
+    <p>This ancient comet witnessed many revolutions in human
+    history, at each of its appearances, even in its later ones, in
+    1682, 1759, 1835; it was also presented to the Earth under the
+    most diverse aspects, passing through a great variety of forms,
+    from the appearance of a curved sabre, as in 1456, to that of a
+    misty head, as in its last visit. Moreover, this is not an
+    exception to the general rule, for these mysterious stars have
+    had the gift of exercising a power on the imagination which
+    plunged it in ecstasy or trouble. Swords of fire, bloody
+    crosses, flaming daggers, spears, dragons, fish, and other
+    appearances of the same kind, were given to them in the middle
+    ages and the Renaissance.</p>
+
+    <p>Comets like those of 1577 appear, moreover, to justify by
+    their strange form the titles with which they are generally
+    greeted. The most serious writers were not free from this
+    terror. Thus, in a chapter on celestial monsters, the
+    celebrated surgeon, Ambroise Paré, described the comet of 1528
+    under the most vivid and frightful colors: "This comet was so
+    horrible and dreadful that it engendered such great terror to
+    the people, that they died, some with fear, others with
+    illness. It appeared to be of immense length, and of blood
+    color; at its head was seen the figure of a curved arm, holding
+    a large sword in the hand as if it wished to strike. At the
+    point of the sword there were three stars, and on either side
+    was seen a great number of hatchets, knives, and swords covered
+    with blood, <span class="pagenum"><a name="page259"
+       id="page259"></a>[pg 259]</span> amongst which were numerous
+       hideous human faces, with bristling beards and hair."</p>
+
+    <p>The imagination has good eyes when it exerts itself. The
+    great and strange variety of cometary aspects is described with
+    exactitude by Father Souciet in his Latin poem on comets. "Most
+    of them," says he, "shine with fires interlaced like thick
+    hair, and from this they have taken the name of comets. One
+    draws after it the twisted folds of a long tail; another
+    appears to have a white and bushy beard; this one throws a
+    glimmer similar to that of a lamp burning during the night;
+    that one, O Titan! represents thy resplendent face; and this
+    other, O Phoebe! the form of thy nascent horns. There are some
+    which bristle with twisted serpents. Shall I speak of those
+    armies which have sometimes appeared in the air? of those
+    clouds which follow as it were along a circle, or which
+    resemble the head of Medusa? Have there not often been seen
+    figures of men or savage animals?</p>
+
+    <p>"Often, in the gloom of night, lighted up by these sad
+    fires, the horrible sound of arms is heard, the clashing of
+    swords which meet in the clouds, the ether furiously resounding
+    with fearful din which crush the people with terror. All comets
+    have a melancholy light, but they have not all the same color.
+    Some have a leaden color; others that of flame or brass. The
+    fires of some have the redness of blood; others resemble the
+    brightness of silver. Some again are azure; others have the
+    dark and pale color of iron. These differences come from the
+    diversity of the vapors which surround them, or from the
+    different manner in which they receive the Sun's rays. Do you
+    not see in our fires, that various <span class=
+    "pagenum"><a name="page260"
+       id="page260"></a>[pg 260]</span> kinds of wood produce
+       different colors? Pines and firs give a flame mixed with
+       thick smoke, and throw out little light. That which rises
+       from sulphur and thick bitumen is bluish. Lighted straw
+       gives out sparks of a reddish color. The large olive,
+       laurel, ash of Parnassus, etc., trees which always retain
+       their sap, throw a whitish light similar to that of a lamp.
+       Thus, comets whose fires are formed of different materials,
+       each take and preserve a color which is peculiar to
+       them."</p>
+
+    <p>Instead of being a cause of fear and terror, the variety and
+    variability of the aspect of comets ought rather to indicate to
+    us the harmlessness of their nature.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/260.png"><img width="500"
+             src="images/260.png"
+             alt="a comet" /></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="page261"
+       id="page261"></a>[pg 261]</span>
+
+    <h2>THE TOTAL SOLAR ECLIPSE OF 1883</h2>
+
+    <h3><i>AN ASTRONOMERS VOYAGE TO FAIRY-LAND.</i></h3>
+
+    <h4>(<span class="sc">From The Atlantic Monthly, May,
+    1890.</span>)</h4>
+
+    <h3><span class="sc">By</span> PROF. E.S. HOLDEN.</h3>
+    <hr class="short" />
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/261.png"><img width="200"
+             src="images/261.png"
+             alt="Solar Eclipse" /></a>
+    </div>
+
+    <p>In 1883 calculations showed that a solar eclipse of
+    unusually long duration (5 minutes, 20 seconds) would occur in
+    the South Pacific Ocean. The track of the eclipse lay south of
+    the equator, but north of Tahiti. There were in fact only two
+    dots of coral islands on the charts in the line of totality,
+    Caroline Island, and one hundred and fifty miles west Flint
+    Island (longitude 150 west, latitude 10 south). Almost nothing
+    was known of either of these minute points. The station of the
+    party under my charge (sent out by the United States government
+    under the direction of the National Academy of Sciences) was to
+    be Caroline Islands.</p>
+
+    <p>Every inch of that island (seven miles long, a mile or so
+    broad) is familiar now; but it is almost ludicrous to recollect
+    with what anxiety we pored over the hydrographic charts and
+    sailing instructions of the various <span class=
+    "pagenum"><a name="page262"
+       id="page262"></a>[pg 262]</span> nations, to find some
+       information, however scanty, about the spot which was to be
+       our home for nearly a month. All that was known was that
+       this island had formerly been occupied as a guano station.
+       There was a landing <i>then</i>.</p>
+
+    <p>After the <i>personnel</i> of the party had been decided on,
+    there were the preparations for its subsistence to be looked
+    out for. How to feed seventeen men for twenty-one days?
+    Fortunately the provisions that we took, and the fresh fish
+    caught for us by the natives, just sufficed to carry us through
+    with comfort and with health.</p>
+
+    <p>In March of 1883 we sailed from New York, and about the same
+    time a French expedition left Europe bound for the same spot.
+    From New York to Panama, from Panama to Lima, were our first
+    steps. Here we joined the United States steamship Hartford,
+    Admiral Farragut's flagship, and the next day set sail for our
+    destined port,&mdash;if a coral reef surrounded by a raging
+    surf can be called a port. About the same time a party of
+    French observers under Monsieur Janssen, of the Paris Academy
+    of Sciences, left Panama in the <i>Eclaireur</i>.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/262.png"><img width="500"
+             src="images/262.png"
+             alt=
+           "BIRD'S EYE VIEW OF THE CAROLINE ISLANDS." /></a><br />
+        BIRD'S EYE VIEW OF THE CAROLINE ISLANDS.
+    </div>
+
+    <p>It was an ocean race of four thousand miles due
+          <span class="pagenum"><a name="page263"
+       id="page263"></a>[pg 263]</span> west. The station Caroline
+       Islands was supposed to be more desirable than Flint Island.
+       Admiral Wilkes's expedition had lain off the latter several
+       days without being able to land on account of the tremendous
+       surf, so that it was eminently desirable to "beat the
+       Frenchman," as the sailors put it. With this end in view our
+       party had secured (through a member of the National Academy
+       in Washington) the verbal promise of the proper official of
+       the Navy Department that the Hartford's orders should read
+       "to burn coal as necessary." The last obstacle to success
+       was thus removed. We were all prepared, and now the ship
+       would take us speedily to our station.</p>
+
+    <p>Imagine our feelings the next day after leaving Callao, when
+    the commanding officer of the Hartford opened his sealed
+    orders. They read (dated Washington, in February), "To arrive
+    at Caroline Islands (in April) with full coal-bunkers!"</p>
+
+    <p>Officialism could go no further. Here was an expedition sent
+    on a slow-sailing ship directly through the regions of calms
+    for four thousand miles. It was of no possible use to send the
+    expedition at all unless it arrived in time. And here were our
+    orders "to arrive with full coal-bunkers."</p>
+
+    <p>Fortunately we had unheard-of good-luck. The trade-wind blew
+    for us as it did for the Ancient Mariner, and we sped along the
+    parallel of 12° south at the rate of one hundred and fifty
+    miles a day under sail, while the <i>Eclaireur</i> was steaming
+    for thirty days a little nearer the equator in a dead calm. We
+    arrived off the island just in time, with not a day to spare.
+    It was a narrow escape, and a warning to all of us never to
+    sail again <span class="pagenum"><a name="page264"
+       id="page264"></a>[pg 264]</span> under sealed orders unless
+       we knew what was under the seal.</p>
+
+    <p>Here we were, then, lying off the island and scanning its
+    sparse crown of cocoanut palms, looking for a French flag among
+    their wavy tufts. There was none in sight. We were the winners
+    in the long race. Directly a whale-boat was lowered, and rowed
+    around the white fringe of tremendous surf that broke
+    ceaselessly against the vertical wall of coral rock. There was
+    just one narrow place where the waves rolled into a sort of
+    cleft and did not break. Here was the "landing," then.</p>
+
+    <p>Landing was an acrobatic feat. In you went on the crest of a
+    wave, pointing for the place where the blue seas did not break
+    into white. An instant after, you were in the quiet water
+    inside of the surf. Jump out everybody and hold the boat! Then
+    it was pick up the various instruments, and carry them for a
+    quarter of a mile to high-water mark and beyond, over the sharp
+    points of the reef.</p>
+
+    <p>In one night we were fairly settled; in another the Hartford
+    had sailed away, leaving us in our fairy paradise, where the
+    corals and the fish were of all the brilliant hues of the
+    rainbow, and where the whiteness of the sand, the emerald of
+    the lagoon, and the turquoise of the ocean made a picture of
+    color and form never to be forgotten.</p>
+
+    <p>But where are the Frenchmen? The next morning there is the
+    <i>Eclaireur</i> lying a mile or so out, and there is a boat
+    with the bo'sun&mdash;<i>maître d'équipage</i>&mdash;pulling
+    towards the surf. I wade out to the brink. He
+    halloes:</p><span class="pagenum"><a name="page265"
+       id="page265"></a>[pg 265]</span>
+
+    <p>"Where is the landing, then?"</p>
+
+    <p>"<i>Mais ici</i>"&mdash;Right here,&mdash;I say.</p>
+
+    <p>"Yes, that's all very well for <i>persons</i>, but where do
+    you land <i>les bagages</i>?"</p>
+
+    <p>"<i>Mais ici</i>" I say again, and he says,
+    "<i>Diable!</i>"</p>
+
+    <p>But all the same he lands both persons and baggage in a
+    neat, sailor-like way. In a couple of days our two parties of
+    fifty persons had taken possession of this fairy isle.
+    Observatories go up, telescopes, spectroscopes, photographic
+    cameras are pointed and adjusted. The eventful day arrives.
+    Everything is successful. Then comes the Hartford and takes us
+    away, and a few days later comes the <i>Eclaireur</i>, and the
+    Frenchmen are gone. The little island is left there, abandoned
+    to the five natives who tend the sickly plantation of
+    cocoa-palms, and live from year to year with no incident but
+    the annual visit of "the blig" (Kanaka for brig), which brings
+    their store of ship biscuit and molasses.</p>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/265.png"><img width="600"
+             src="images/265.png"
+             alt="'OBSERVATORIES GO UP.'" /></a><br />
+        "OBSERVATORIES GO UP."
+    </div>
+
+    <p>Think of their stupendous experience! For years and years
+    they have lived like that in the marvellous, continuous charm
+    of the silent island. The "blig" <span class=
+       "pagenum"><a name="page266"
+       id="page266"></a>[pg 266]</span> had come and gone away this
+       year, and there will be no more disturbance and discord for
+       a twelve-month longer.</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p>"Surely, surely, slumber is more sweet than toil,
+            the shore</p>
+
+            <p>Than labor in the deep mid-ocean, wind, and wave,
+            and oar,</p>
+
+            <p>Then rest ye, brother mariners, we will not wander
+            more!"</p>
+        </div>
+    </div>
+
+    <p>Not so! for here comes a great warship out of the East under
+    a press of canvas. What event is this? See! she clews up her
+    light sails and fires an eleven-inch gun! One of those guns of
+    Mobile Bay. Then swarms out the starboard watch, one hundred
+    and sixty strong, and a fleet of boats brings ashore these pale
+    astronomers with those useless tubes that they point at the sky
+    every night. But there are useful things too; cooking-stoves,
+    and lumber, and bricks.</p>
+
+    <p>What is all this? No sooner are these established than comes
+    another ship and fires its gun! and another set of hardy
+    sailormen pours out, and here is another party of madmen with
+    tubes,&mdash;yes, and with cooking-stoves and lumber, too. Then
+    comes the crowning, stupendous, and unspeakable event. The
+    whole sun is hidden and the heavens are lighted up with pearly
+    streamers! In the name of all the Polynesian gods, what is the
+    meaning of all this?</p>
+
+    <p>And then in a few days all these are gone. All the madmen.
+    They have taken away the useless tubes, but they have left
+    their houses standing. Their splendid, priceless, precious
+    cook-stoves are here. See! here is a frying-pan! here are empty
+    tin cans! and a keg of nails! They must have forgotten all
+    this, madmen as they are!</p><span class="pagenum"><a name=
+    "page267"
+       id="page267"></a>[pg 267]</span>
+
+    <p>And the little island sinks back to its quiet and its calm.
+    The lagoon lies placid like a mirror. The slow sea breaks
+    eternally on the outer reef. The white clouds sail over day by
+    day. The seabirds come back to their haunts,&mdash;the fierce
+    man-of-war birds, the gentle, soft-eyed tern. But we, whose
+    island home was thus invaded&mdash;are we the same? Was this a
+    dream? Will it happen again next year? every year? What indeed
+    was it that happened,&mdash;or in fact, did it happen at all?
+    Is it not a dream, indeed?</p>
+
+    <p>If we left those peaceful Kanakas to their dream, we
+    Americans have brought ours away with us. Who will forget it?
+    Which of us does not wish to be in that peaceful fairyland once
+    more? That is the personal longing. But we have all come back,
+    each one with his note-books full; and in a few weeks the
+    stimulus of accustomed habit has taken possession of us again.
+    Right and wrong are again determined by "municipal sanctions."
+    We have become useful citizens once more. Perhaps it is just as
+    well. We should have been poor poets, and we do not forget. So
+    ends the astronomer's voyage to fairyland.</p>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/267.png"><img width="400"
+             src="images/267.png"
+             alt="Peaceful Island" /></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="page268"
+       id="page268"></a>[pg 268]</span>
+
+    <h2>HALOS&mdash;PARHELIA&mdash;THE SPECTRE OF THE BROCKEN,
+    ETC</h2>
+
+    <h4>(<span class="sc">From The Atmosphere.</span>)</h4>
+
+    <h3><span class="sc">By</span> CAMILLE FLAMMARION.</h3>
+    <hr class="short" />
+
+    <div class="figleft"
+         style="width:231px;">
+        <a href="images/268.png"><img width="231"
+             src="images/268.png"
+             alt="Rainbow" /></a>
+    </div>
+
+    <p>Treatises on meteorology have not, up to the present day,
+    classified with sufficient regularity the divers optical
+    phenomena of the air. Some of these phenomena have, however,
+    been seen but rarely, and have not been sufficiently studied to
+    admit of their classification. We have examined the common
+    phenomenon of the rainbow and we have seen that it is due to
+    the refraction and reflection of light on drops of water, and
+    that it is seen upon the opposite side of the sky to the sun in
+    day-time, or the moon at night. We are now about to consider an
+    order of phenomena which are of rarer occurrence, but which
+    have this property in common with the rainbow, viz., that they
+    take place also upon the side of the sky opposite to the sun.
+    These different optical effects are <span class=
+    "pagenum"><a name="page269"
+       id="page269"></a>[pg 269]</span> classed together under the
+       name of <i>anthelia</i> (from Greek, opposite to, and Greek,
+       the sun). The optical phenomena which occur on the same side
+       as, or around the sun, such as halos, parhelia, etc., will
+       be dealt with later on.</p>
+
+    <p>Before coming to the anthelia, properly so called, or to the
+    colored rings which appear around a shadow, it is as well first
+    to note the effects produced on the clouds and mists that are
+    facing the sun when it rises or sets.</p>
+
+    <p>Upon high mountains, the shadow of the mountain is often
+    seen thrown either upon the surface of the lower mists or upon
+    the neighboring mountains, and projected opposite to the sun
+    almost horizontally. I once saw the shadow of the Righi very
+    distinctly traced upon Mount Pilate, which is situated to the
+    west of the Righi, on the other side of the Lake of Lucerne.
+    This phenomenon occurs a few minutes after sunrise, and the
+    triangular form of Righi is delineated in a shape very easy to
+    recognize.</p>
+
+    <p>The shadow of Mont Blanc is discerned more easily at sunset.
+    MM. Bravais and Martins, in one of their scientific ascents,
+    noticed it under specially favorable circumstances, the shadow
+    being thrown upon the snow-covered mountains, and gradually
+    rising in the atmosphere until it reached a height of 1°, still
+    remaining quite visible. The air above the cone of the shadow
+    was tinted with that rosy purple which is seen, in a fine
+    sunset, coloring the lofty peaks. "Imagine," says Bravais, "the
+    other mountains also projecting, at the same moment, their
+    shadows into the atmosphere, the lower parts dark and slightly
+    greenish, and above each of these shadows the rosy surface,
+    with the deeper rose <span class="pagenum"><a name="page270"
+       id="page270"></a>[pg 270]</span> of the belt which separates
+       it from them; add to this the regular contour of the cones
+       of the shadow, principally at the upper edge, and lastly,
+       the laws of perspective causing all these lines to converge
+       the one to the other toward the very summit of the shadow of
+       Mont Blanc; that is to say, to the point of the sky where
+       the shadows of our own selves were; and even then one will
+       have but a faint idea of the richness of the meteorological
+       phenomenon displayed before our eyes for a few instants. It
+       seemed as though an invisible being was seated upon a throne
+       surrounded by fire, and that angels with glittering wings
+       were kneeling before him in adoration."</p>
+
+    <p>Among the natural phenomena which now attract our attention,
+    but fail to excite our surprise, there are some which possess
+    the characteristics of a supernatural intervention. The names
+    which they have received still bear witness to the terror which
+    they once inspired; and even to-day, when science has stripped
+    them of their marvellous origin, and explained the causes of
+    their production, these phenomena have retained a part of their
+    primitive importance, and are welcomed by the <i>savant</i>
+    with as much interest as when they were attributed to divine
+    agency. Out of a large and very diverse number, I will first
+    select the <i>Spectre of the Brocken</i>.</p>
+
+    <p>The Brocken is the highest mountain in the picturesque Hartz
+    chain, running through Hanover, being three hundred and thirty
+    feet above the level of the sea.</p>
+
+    <p>One of the best descriptions of this phenomenon is given by
+    the traveller Hane, who witnessed it on the 23d of May, 1797.
+    After having ascended no less than <span class=
+    "pagenum"><a name="page271"
+       id="page271"></a>[pg 271]</span> thirty miles to the summit,
+       he had the good fortune at last to contemplate the object of
+       his curiosity. The sun rose at about four o'clock, the
+       weather being fine, and the wind driving off to the west the
+       transparent vapors which had not yet had time to be
+       condensed into clouds. About a quarter-past four, Hane saw
+       in this direction a human figure of enormous dimensions. A
+       gust of wind nearly blowing off his hat at that moment, he
+       raised his hand to secure it, and the colossal figure
+       imitated his action. Hane, noticing this, at once made a
+       stooping movement, and this was also reproduced by the
+       spectre. He then called another person to him, and placing
+       themselves in the very spot where the apparition was first
+       seen, the pair kept their eyes fixed on the Achtermannshohe,
+       but saw nothing. After a short interval, however, two
+       colossal figures appeared, which repeated the gestures made
+       by them, and then disappeared.</p>
+
+    <p>Some few years ago, in the summer of 1862, a French artist,
+    M. Stroobant, witnessed and carefully sketched this phenomenon,
+    which is drawn in full-page illustration, opposite p. 272. He
+    had slept at the inn of the Brocken, and rising at two in the
+    morning, he repaired to the plateau upon the summit in the
+    company of a guide. They reached the highest point just as the
+    first glimmer of the rising sun enabled them to distinguish
+    clearly objects at a great distance. To use M. Stroobant's own
+    words, "My guide, who had for some time appeared to be walking
+    in search of something, suddenly led me to an elevation whence
+    I had the singular privilege of contemplating for a few
+    instants the magnificent effect of mirage, which is termed the
+    Spectre <span class="pagenum"><a name="page272"
+       id="page272"></a>[pg 272]</span> of the Brocken. The
+       appearance is most striking. A thick mist, which seemed to
+       emerge from the clouds like an immense curtain, suddenly
+       rose to the west of the mountain, a rainbow was formed, then
+       certain indistinct shapes were delineated. First, the large
+       tower of the inn was reproduced upon a gigantic scale; after
+       that we saw our two selves in a more vague and less exact
+       shape, and these shadows were in each instance surrounded by
+       the colors of the rainbow, which served as a frame to this
+       fairy picture. Some tourists who were staying at the inn had
+       seen the sun rise from their windows, but no one had
+       witnessed the magnificent spectacle which had taken place on
+       the other side of the mountain."</p>
+
+    <p>Sometimes these spectres are surrounded by colored
+    concentric arcs. Since the beginning of the present century,
+    treatises on meteorology designate, under the name of the
+    <i>Ulloa circle</i>, the pale external arch which surrounds the
+    phenomenon, and this same circle has sometimes been called the
+    "white rainbow." But it is not formed at the same angular
+    distance as the rainbow, and, although pale, it often envelops
+    a series of interior colored arcs.</p>
+
+    <div class="figcenter"
+         style="width:300px;">
+        <a href="images/303.jpg"><img width="300"
+             src="images/303sm.jpg"
+             alt="'THE SPECTRE OF THE BROCKEN'" /></a><br />
+        "THE SPECTRE OF THE BROCKEN"
+    </div>
+
+    <p>Ulloa, being in company with six fellow-travellers upon the
+    Pambamarca at daybreak one morning, observed that the summit of
+    the mountain was entirely covered with thick clouds, and that
+    the sun, when it rose, dissipated them, leaving only in their
+    stead light vapors, which it was almost impossible to
+    distinguish. Suddenly, in the opposite direction to where the
+    sun was rising, "each of the travellers beheld, at about
+    seventy feet from where he was standing, his own
+          <span class="pagenum"><a name="page273"
+       id="page273"></a>[pg 273]</span> image reflected in the air
+       as in a mirror. The image was in the centre of three
+       rainbows of different colors, and surrounded at a certain
+       distance by a fourth bow with only one color. The inside
+       color of each bow was carnation or red, the next shade was
+       violet, the third yellow, the fourth straw color, the last
+       green. All these bows were perpendicular to the horizon;
+       they moved in the direction of, and followed, the image of
+       the person they enveloped as with a glory." The most
+       remarkable point was that, although the seven spectators
+       were standing in a group, each person only saw the
+       phenomenon in regard to his own person, and was disposed to
+       disbelieve that it was repeated in respect to his
+       companions. The extent of the bows increased continually and
+       in proportion to the height of the sun; at the same time
+       their colors faded away, the spectre <span class=
+       "pagenum"><a name="page274"
+       id="page274"></a>[pg 274]</span> became paler and more
+       indistinct, and finally the phenomenon disappeared
+       altogether. At the first appearance the shape of the bows
+       was oval, but toward the end they became quite circular. The
+       same apparition was observed in the polar regions by
+       Scoresby, and described by him. He states that the
+       phenomenon appears whenever there is mist and at the same
+       time shining sun. In the polar seas, whenever a rather thick
+       mist rises over the ocean, an observer, placed on the mast,
+       sees one or several circles upon the mist.</p>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/273.png"><img width="600"
+             src="images/273.png"
+             alt="THE ULLOA CIRCLE." /></a><br />
+        THE ULLOA CIRCLE.
+    </div>
+
+    <p>These circles are concentric, and their common centre is in
+    the straight line joining the eye of the observer to the sun,
+    and extended from the sun toward the mist. The number of
+    circles varies from one to five; they are particularly numerous
+    and well colored when the sun is very brilliant and the mist
+    thick and low. On July 23, 1821, Scoresby saw four concentric
+    circles around his head. The colors of the first and of the
+    second were very well defined; those of the third, only visible
+    at intervals, were very faint, and the fourth only showed a
+    slight greenish tint.</p>
+
+    <p>The meteorologist Kaemtz has often observed the same fact in
+    the Alps. Whenever this shadow was projected upon a cloud, his
+    head appeared surrounded by a luminous aureola.</p>
+
+    <p>To what action of light is this phenomenon due? Bouguer is
+    of opinion that it must be attributed to the passage of light
+    through icy particles. Such, also, is the opinion of De
+    Saussure, Scoresby, and other meteorologists.</p>
+
+    <p>In regard to the mountains, as we cannot assure ourselves
+    directly of the fact by entering the clouds, we
+          <span class="pagenum"><a name="page275"
+       id="page275"></a>[pg 275]</span> are reduced to conjecture.
+       The aerostat traversing the clouds completely, and passing
+       by the very point where the apparition is seen, affords one
+       an opportunity of ascertaining the state of the cloud. This
+       observation I have been able to make, and so to offer an
+       explanation of the phenomenon.</p>
+
+    <p>As the balloon sails on, borne forward by the wind, its
+    shadow travels either on the ground or on the clouds. This
+    shadow is, as a rule, black, like all others; but it frequently
+    happens that it appears alone on the surface of the ground, and
+    thus appears luminous. Examining this shadow by the aid of a
+    telescope, I have noticed that it is often composed of a dark
+    nucleus and a penumbra of the shape of an aureola. This
+    aureola, frequently very large in proportion to the diameter of
+    the central nucleus, eclipses it to the naked eye, so that the
+    whole shadow appears like a nebulous circle projected in yellow
+    upon the green ground of the woods and meadows. I have noticed,
+    too, that this luminous shadow is generally all the more
+    strongly marked in proportion to the greater humidity of the
+    surface of the ground.</p>
+
+    <p>Seen upon the clouds, this shadow sometimes presents a
+    curious aspect. I have often, when the balloon emerged from the
+    clouds into the clear sky, suddenly perceived, at twenty or
+    thirty yards' distance, a second balloon distinctly delineated,
+    and apparently of a grayish color, against the white ground of
+    the clouds. This phenomenon manifests itself at the moment when
+    the sun re-appears. The smallest details of the car can be made
+    out clearly, and our gestures are strikingly reproduced by the
+    shadow.</p><span class="pagenum"><a name="page276"
+       id="page276"></a>[pg 276]</span>
+
+    <div class="figcenter"
+         style="width:600px;">
+        <a href="images/276.png"><img width="600"
+             src="images/276.png"
+             alt=
+           "THE SHADOW OF THE BALLOON WAS SEEN BY US." /></a><br />
+        THE SHADOW OF THE BALLOON WAS SEEN BY US.
+    </div>
+
+    <p>On April 15, 1868, at about half-past three in the
+    afternoon, we emerged from a stratum of clouds, when the shadow
+    of the balloon was seen by us, surrounded by colored concentric
+    circles, of which the car formed the centre. It was very
+    plainly visible upon a yellowish white ground. A first circle
+    of pale blue encompassed this ground and the car in a kind of
+    ring. Around this ring was a second of a deeper yellow, then a
+    grayish red zone, and lastly as the exterior circumference, a
+    fourth circle, violet in hue, and imperceptibly toning down
+    into the gray tint of the clouds. The slightest details were
+    clearly discernible&mdash;net, robes, and instruments. Every
+    one of our gestures was instantaneously reproduced by the
+    aerial spectres. The anthelion remained upon the clouds
+    sufficiently distinct, and for a sufficiently long time, to
+    permit of my taking a sketch in my journal and studying the
+    physical <span class="pagenum"><a name="page277"
+       id="page277"></a>[pg 277]</span> condition of the clouds
+       upon which it was produced. I was able to determine directly
+       the circumstances of its production. Indeed, as this
+       brilliant phenomenon occurred in the midst of the very
+       clouds which I was traversing, it was easy for me to
+       ascertain that these clouds were not formed of frozen
+       particles. The thermometer marked 2° above zero. The
+       hygrometer marked a maximum of humidity experienced, namely,
+       seventy-seven at three thousand seven hundred and seventy
+       feet, and the balloon was then at four thousand six hundred
+       feet, where the humidity was only seventy-three. It is
+       therefore certain that this is a phenomenon of the
+       diffraction of light simply produced by the vesicles of the
+       mist.</p>
+
+    <p>The name of diffraction is given to all the modifications
+    which the luminous rays undergo when they come in contact with
+    the surface of bodies. Light, under these circumstances, is
+    subject to a sort of deviation, at the same time becoming
+    decomposed, whence result those curious appearances in the
+    shadows of objects which were observed for the first time by
+    Grimaldi and Newton.</p>
+
+    <p>The most interesting phenomena of diffraction are those
+    presented by <i>gratings</i>, as are technically denominated
+    the systems of linear and very narrow openings situated
+    parallel to one another and at very small intervals. A system
+    of this kind may be realized by tracing with a diamond, for
+    instance, on a pane of glass equidistant lines very close
+    together. As the light would be able to pass in the interstices
+    between the strokes, whereas it would be stopped in the points
+    corresponding to those where the glass was not smooth,
+    <span class="pagenum"><a name="page278"
+       id="page278"></a>[pg 278]</span> there is, in reality, an
+       effect produced as if there were a series of openings very
+       near to each other. A hundred strokes, about 1/25th of an
+       inch in length, may thus be drawn without difficulty. The
+       light is then decomposed in spectra, each overlapping the
+       other. It is a phenomenon of this kind which is seen when we
+       look into the light with the eye half closed; the eyelashes
+       in this case, acting as a net-work or grating. These
+       net-works may also be produced by reflection, and it is to
+       this circumstance that are due the brilliant colors observed
+       when a pencil of luminous rays is reflected on a metallic
+       surface regularly striated.</p>
+
+    <p>To the phenomena of gratings must be attributed, too, the
+    colors, often so brilliant, to be seen in mother-of-pearl. This
+    substance is of a laminated structure; so much so, that in
+    carving it the different folds are often cut in such a way as
+    to form a regular net-work upon the surface. It is, again, to a
+    phenomenon of this sort that are due the rainbow hues seen in
+    the feathers of certain birds, and sometimes in spiders' webs.
+    The latter, although very fine, are not simple, for they are
+    composed of a large number of pieces joined together by a
+    viscous substance, and thus constitute a kind of net-work.</p>
+
+    <p>If the sun is near the horizon, and the shadow of the
+    observer falls upon the grass, upon a field of corn, or other
+    surface covered with dew, there is visible an aureola, the
+    light of which is especially bright about the head, but which
+    diminishes from below the middle of the body. This light is due
+    to the reflection of light by the moist stubble and the drops
+    of dew. It is brighter about the head, because the blades that
+    are <span class="pagenum"><a name="page279"
+       id="page279"></a>[pg 279]</span> near where the shadow of
+       the head falls expose to it all that part of them which is
+       lighted up, whereas those farther off expose not only the
+       part which is lighted up, but other parts which are not, and
+       this diminishes the brightness in proportion as their
+       distance from the <span class="pagenum"><a name="page280"
+       id="page280"></a>[pg 280]</span> head increases. The
+       phenomenon is seen whenever there is simultaneously mist and
+       sun. This fact is easily verified upon a mountain. As soon
+       as the shadow of a mountaineer is projected upon a mist, his
+       head gives rise to a shadow surrounded by a luminous
+       aureola.</p>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/279.jpg"><img width="400"
+             src="images/279.jpg"
+             alt="FOG-BOW SEEN FROM THE MATTERHORN." /></a><br />
+        FOG-BOW SEEN FROM THE MATTERHORN.
+    </div>
+
+    <p><i>The Illustrated London News</i> of July 8, 1871,
+    illustrates one of these apparitions, "The Fog-Bow, seen from
+    the Matterhorn," observed by E. Whymper in this celebrated
+    region of the Alps. The observation was taken just after the
+    catastrophe of July 14, 1865; and by a curious coincidence, two
+    immense white aerial crosses projected into the interior of the
+    external arc. These two crosses were no doubt formed by the
+    intersection of circles, the remaining parts of which were
+    invisible. The apparition was of a grand and solemn character,
+    further increased by the silence of the fathomless abyss into
+    which the four ill-fated tourists had just been
+    precipitated.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/280.png"><img width="500"
+             src="images/280.png"
+             alt="Optical appearance" /></a>
+    </div>
+
+    <p>Other optical appearances of an analogous kind are
+    manifested under different conditions. Thus, for instance, if
+    any one, turning his back to the sun, looks into water, he will
+    perceive the shadow of his head, but always very much deformed.
+    At the same time he will see starting from this very shadow
+    what seem to be <span class="pagenum"><a name="page281"
+       id="page281"></a>[pg 281]</span> luminous bodies, which dart
+       their rays in all directions with inconceivable rapidity,
+       and to a great distance. These luminous
+       appearances&mdash;these aureola rays&mdash;have, in addition
+       to the darting movement, a rapid rotary movement around the
+       head.</p>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/281.png"><img width="400"
+             src="images/281.png"
+             alt="decorative picture" /></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="page282"
+       id="page282"></a>[pg 282]</span>
+
+    <h2>THE PLANET VENUS</h2>
+
+    <h3><span class="sc">By</span> AGNES M. CLERKE.</h3>
+    <hr class="short" />
+
+    <h2>I.</h2>
+
+    <h3>HESPERUS AND PHOSPHOR.</h3>
+
+    <div class="figleft"
+         style="width:175px;">
+        <a href="images/282.png"><img width="175"
+             src="images/282.png"
+             alt="Torch carrier" /></a>
+    </div>
+
+    <p>The radiant planet that hangs on the skirts of dusk and
+    dawn</p>
+
+    <blockquote>
+        <p>"like a jewel in an Ethiop's ear,"</p>
+    </blockquote>
+
+    <p>has been known and sung by poets in all ages. Its supremacy
+    over the remainder of the starry host is recognized in the name
+    given it by the Arabs, those nomad watchers of the skies, for
+    while they term the moon "El Azhar," "the Brighter One," and
+    the sun and moon together "El Azharan," "the Brighter Pair,"
+    they call Venus "Ez Zahra," the bright or shining one <i>par
+    excellence</i>, in which sense the same word is used to
+    describe a flower. This "Flower of Night" is supposed to be no
+    other than the white rose into which Adonis was changed by
+    Venus in the fable which is the basis of all early Asiatic
+    mythology. The morning and evening star is thus the celestial
+    symbol <span class="pagenum"><a name="page283"
+       id="page283"></a>[pg 283]</span> of that union between earth
+       and heaven in the vivifying processes of nature, typified in
+       the love of the goddess for a mortal.</p>
+
+    <p>The ancient Greeks, on the other hand, not unnaturally took
+    the star, which they saw alternately emerging from the
+    effulgence of the rising and setting sun, in the east and in
+    the west, for two distinct bodies, and named it differently
+    according to the time of its appearance. The evening star they
+    called Hesperus, and from its place on the western horizon,
+    fabled an earthly hero of that name, the son of Atlas, who from
+    the slopes of that mountain on the verge of the known world
+    used to observe the stars until eventually carried off by a
+    mighty wind, and so translated to the skies. These divine
+    honors were earned by his piety, wisdom, and justice as a ruler
+    of men, and his name long shed a shimmering glory over those
+    Hesperidean regions of the earth, where the real and unreal
+    touched hands in the mystical twilight of the unknown.</p>
+
+    <p>But the morning star shone with a different significance as
+    the herald of the day, the torchbearer who lights the way for
+    radiant Aurora on her triumphal progress through the skies.
+    Hence he was called Eosphorus, or Phosphorus, the bearer of the
+    dawn, translated into Latin as Lucifer, the Light-bearer. The
+    son of Eos, or Aurora, and the Titan Astraeus, he was of the
+    same parentage as the other multitude of the starry host, to
+    whom a similar origin was ascribed, and from whom in Greek
+    mythology he was evidently believed to differ only in the
+    superior order of his brightness. Homer, who mentions the
+    planet in the following passage:</p><span class=
+    "pagenum"><a name="page284"
+       id="page284"></a>[pg 284]</span>
+
+    <div class="poem">
+        <div class="stanza">
+            <p>"But when the star of Lucifer appeared,</p>
+
+            <p>The harbinger of light, whom following close,</p>
+
+            <p>Spreads o'er the sea the saffron-robed morn."</p>
+
+            <p class="i30">(<span class="sc">Lord Derby's</span>
+            "Iliad.")</p>
+        </div>
+    </div>
+
+    <p>recognizes no distinction between those celestial nomads,
+    the planets, "wandering stars," as the Arabs call them, which
+    visibly change their position relatively to the other stars,
+    and the latter, whose places on the sphere are apparently fixed
+    and immutable. In this he and his compatriots were far behind
+    the ancient Egyptians, who probably derived their knowledge
+    from still earlier speculators in Asia, for they not only
+    observed the movements of some at least of the planets, but
+    believed that Mercury and Venus revolved as satellites round
+    the sun, which in its turn circled round our lesser world.
+    Pythagoras is said to have been the first to identify Hesperus
+    with Phosphor, as the</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p class="i10">"Silver planet both of eve and
+            morn,"</p>
+        </div>
+    </div>
+
+    <p>and by Plato the same fact is recognized. The other planets,
+    all of which had, according to him, been originally named in
+    Egypt and Syria, have each its descriptive title in his
+    nomenclature. Thus the innermost, "the Star of Mercury," is
+    called Stilbon, "the Sparkler," Mars, Pyroeis, "the Fiery One,"
+    while Jupiter, the planet of the slowest course but one, is
+    designated as Phaeton, and Saturn, the tardiest of all,
+    Phaenon. These names were in later times abandoned in favor of
+    those of the divinities to whom they were respectively
+    dedicated, unalterably associated now with the days of the
+    week, over which they have been selected to
+    preside.</p><span class="pagenum"><a name="page285"
+       id="page285"></a>[pg 285]</span>
+
+    <p>The Copernican theory, which once and forever "brushed the
+    cobwebs out of the sky," by clearing away the mists of
+    pre-existing error, first completely explained the varying
+    positions of the Shepherd's star, irradiating the first or last
+    watch of night, according to her alternate function as the
+    follower or precursor of the sun. As she travels on a path
+    nearer to him by more than twenty-five and a half million miles
+    than that of the earth, she is seen by us on each side of him
+    in turn after passing behind or in front of him. The points at
+    which her orbit expands most widely to our eyes&mdash;an effect
+    of course entirely due to perspective, as her distance from the
+    sun is not then actually increased&mdash;are called her eastern
+    and western elongations; that at which she passes by the sun on
+    the hither side her inferior, and on the farther side her
+    superior conjunction. At both conjunctions she is lost to our
+    view, since she accompanies the sun so closely as to be lost in
+    his beams, rising and setting at the same time, and travelling
+    with him in his path through the heavens during the day. When
+    at inferior conjunction, or between us and the sun, she turns
+    her dark hemisphere to us like the new moon, and would
+    consequently be invisible in any case, but when in the opposite
+    position, shows us her illuminated face, and is literally a day
+    star, invisible only because effaced by the solar splendor. It
+    is as she gradually separates from him, after leaving this
+    latter position, circling over that half of her orbit which
+    lies to the east of him, that she begins to come into view as
+    an evening star, following him at a greater and greater
+    distance, and consequently setting later, until she attains her
+    greatest <span class="pagenum"><a name="page286"
+       id="page286"></a>[pg 286]</span> eastern elongation, divided
+       from the sun about 45° of his visible circuit through the
+       heavens, and consequently remaining above the horizon for
+       some four hours after him. From this point she again appears
+       to draw nearer to him until she passes on his hither side in
+       inferior conjunction, from which she emerges on the opposite
+       side to the westward, and begins to shine as a morning star,
+       preceding him on his track, at a gradually increasing
+       distance, until attaining her greatest westward elongation,
+       and finally completing her cycle by returning to superior
+       conjunction once more in a period of about five hundred and
+       eighty-four days.</p>
+
+    <p>Venus is thus Hesperus or Vesper, the evening star, when
+    following the sun as she passes from beyond him in superior
+    conjunction to inferior conjunction where she is nearest to the
+    earth. As she again leaves him behind in her course from this
+    point to the opposite one of superior conjunction, she appears
+    in her second aspect as Phosphorus or Lucifer, "the sun of
+    morning," and herald of the day, shining as</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p class="i22">"The fair star</p>
+
+            <p>That gems the glittering coronet of morn."</p>
+        </div>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <h2>II.</h2>
+
+    <h3>THE PHASES OF VENUS.</h3>
+
+    <p>But the changes in the aspect of Venus due to her varying
+    positions in her orbit are not confined to those which cause
+    her to oscillate with a pendulum movement eastward and westward
+    from the sun. The discovery that she undergoes phases exactly
+    like those of the moon, followed that of the existence of
+    Jupiter's <span class="pagenum"><a name="page287"
+       id="page287"></a>[pg 287]</span> satellites as the second
+       great result achieved by the use of the telescope in the
+       hands of Galileo. The fact that the planets were
+       intrinsically dark bodies revolving round the sun, and
+       reflecting its light, as he and Copernicus had maintained,
+       thus received a further ocular demonstration. The Florentine
+       astronomer describes in a letter to a friend how the planet,
+       after emerging from superior conjunction as a morning star,
+       gradually loses her rotundity on the side remote from the
+       luminary, changing first to a half sphere and then to a
+       waning crescent; until, after passing through the stage of
+       absolute extinction when intervening between us and the sun,
+       she re-appears as a morning star, and undergoes the same
+       series of transformations in inverse order. The revelation
+       was indeed so novel and unexpected, that when the slight
+       deformation of the planet's shape was first detected by him,
+       he did not venture to announce it in plain terms but veiled
+       it, according to the prevailing fashion of the time, under a
+       Latin anagram. His celebrated sentence&mdash;</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p>"Haec immatura a me jam frustra leguntur."</p>
+        </div>
+    </div>
+
+    <p>("Those incomplete observations are as yet read by me in
+    vain.")</p>
+
+    <p>forms, by transposing the letters, the more definite
+    statement,</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p>"Cynthiæ figuras æmulatur Mater Amorum."</p>
+        </div>
+    </div>
+
+    <p>("The mother of the loves imitates the aspects of Diana.")
+    <span class="pagenum"><a name="page288"
+       id="page288"></a>[pg 288]</span> that is to say, Venus vies
+       with the phases of the moon. The discovery was an important
+       one from its bearing on popular superstition ascribing to
+       the planets special influences on human affairs, for since
+       they were thus shown to transmit to us only borrowed light,
+       belief in their beneficent or malefic powers over man's
+       destinies received a rude shock.</p>
+
+    <div class="figright"
+         style="width:350px;">
+        <a href="images/287.png"><img width="350"
+             src="images/287.png"
+             alt="THE PHASES OF VENUS." /></a><br />
+        THE PHASES OF VENUS.
+    </div>
+
+    <p>Galileo's announcement, published in September, 1610, when
+    only a slight flattening of the planet's disk was visible,
+    received absolute confirmation in the ensuing months, as she
+    completed her full half-circle of change on February 24th of
+    the following year, and consequently exhibited herself to him
+    in all her varying aspects. It was the first time they had been
+    looked upon by a human eye, since its unaided powers do not
+    enable it to discern them, although one exception to this rule
+    is said to have existed. This was the case of the Swiss
+    mathematician Gauss, who, when a child, on being shown the
+    crescent star through the telescope, exclaimed to his mother
+    that it "was turned wrong"; the inference being that he
+    recognized the reversal of the image in the field of the glass.
+    If it were indeed so, he deserves to rank with the Siberian
+    savage, who described the eclipses, or Jupiter's satellites; or
+    the shoemaker of Breslau, who could see and declare the
+    positions of those minute orbs.</p>
+
+    <p>The phases exhibited to us by Venus are due to her moving in
+    an orbit within that of the earth, at one side of which she is
+    between us and the sun, while at the other this position is
+    exactly reversed. We may compare her to a performer in a great
+    celestial circus, lit by a central chandelier, and ourselves to
+    spectators in an <span class="pagenum"><a name="page289"
+       id="page289"></a>[pg 289]</span> external ring, from which
+       we see her at one time facing us with the light full on her,
+       at the opposite point in complete shadow, and at the
+       intermediate ones in varying degrees of illumination
+       according to our changing views of her. The same
+       illustration may serve to show why Venus is brightest, not
+       when full, since she is then beyond the sun, and at the
+       farthest possible point from us, but when she approaches us
+       at inferior conjunction, more nearly by over one hundred and
+       thirty million miles, and still shows us a crescent of her
+       illuminated surface, before passing into the last phase of
+       total obscuration. When actually nearest to us she is
+       absolutely invisible, being then, like the new moon, between
+       us and the sun. Her varying degrees of brilliancy, even when
+       in the same phase, are thus accounted for by her alternate
+       retreat from and advance towards us as she circles round the
+       sun. Completing, as she does, her revolution in about seven
+       months and a half, she would of course go through the whole
+       series of her metamorphoses in that time, were the earth,
+       from which we observe them, a fixed point. Their protraction
+       instead, over a term of five hundred and eighty-four days,
+       or more than nineteen months, is due to the simultaneous
+       motion of the earth in the same direction, over her larger
+       orbit in a longer period, causing the same relative position
+       of the sister planet to recur only as often as she overtakes
+       her in her career. Thus the hour and minute hands of a
+       watch, moving at different rates of speed after meeting on
+       the dial plate at twelve o'clock, will not again come
+       together until five minutes past one, when the swifter paced
+       of the two will have completed a revolution and a twelfth.
+       But were we to <span class="pagenum"><a name="page290"
+       id="page290"></a>[pg 290]</span> retard the motion of the
+       latter, reducing it to only twice that of its companion,
+       they would always meet at the figure twelve, as it would
+       exactly complete two circuits while the hour hand was
+       performing one. Venus thus overtakes and passes the earth
+       once in five hundred and eighty-four days, or nearly two and
+       a half of her own years, constituting what is called her
+       synodic period of apparent revolution as seen from this
+       globe. She thus presents to us all the phases undergone by
+       our own satellite during a lunar month, passing from new to
+       full, and <i>vice versa</i>, through the various intervening
+       gradations of form.</p>
+
+    <p>The phases of Venus are amongst the most beautiful subjects
+    for observation in a moderate telescope, as her silver bow,
+    gradually brightening in the evening dusk, or fading in the
+    dawn,</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p>"On a bed of daffodil sky,"</p>
+        </div>
+    </div>
+
+    <p>is, after the two greater luminaries that rule the day and
+    night, the most brilliant object in the heavens.</p>
+
+    <p>&nbsp;</p>
+
+    <h2>III.</h2>
+
+    <h3>THE SILVER CROWN.</h3>
+
+    <p>The parallel between Venus and</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p>"That orbed maiden with fire laden,</p>
+
+            <p>Whom mortals call the moon,"</p>
+        </div>
+    </div>
+
+    <p>is carried a stage further. Most of us are familiar with the
+    spectacle in which the Ancient Egyptians saw symbolized Horus
+    on the lap of Isis, but which we more prosaically term "the old
+    moon in the new moon's <span class="pagenum"><a name="page291"
+       id="page291"></a>[pg 291]</span> arms." The strongly
+       illuminated half circle next the sun is then seen embracing
+       with its horns a dusky sphere, contrasting with it as
+       tarnished silver does with the newly burnished metal. The
+       same phenomenon is occasionally, though very rarely,
+       exhibited by Venus, while close to the sun at inferior
+       injunction, when the shadowy form of the full orb is seen to
+       shine dimly within her crescent with what is termed "the
+       ashen light." More wonderful still, this "glimmering sphere"
+       is then crowned, as with a silver halo, by a thin luminous
+       arch, forming a secondary sickle facing the one nearest the
+       sun, and doubtless due to the refraction of his rays round
+       the globe of the planet, through the upper regions of her
+       twilight atmosphere. This spectacle was first observed by
+       the Jesuit Ricciolo, an opponent of the Copernican theory,
+       on January 9th, 1643. He describes the planet as ruddy near
+       the sun, yellowish in the middle, and of greenish blue on
+       the side remote from the sun; while he also noted the bow of
+       light limiting the dark hemisphere. Scarcely daring to trust
+       his own eyesight, he ascribed these appearances, although he
+       recorded them, to illusory reflection in the telescope.</p>
+
+    <div class="figright"
+         style="width:300px;">
+        <a href="images/291.png"><img width="300"
+             src="images/291.png"
+             alt="VENUS AT HER GREATEST BRILLIANCY." /></a><br />
+        VENUS AT HER GREATEST BRILLIANCY.
+    </div>
+
+    <p>They were again seen, however, by Derham about
+          <span class="pagenum"><a name="page292"
+       id="page292"></a>[pg 292]</span> 1715, and six years later
+       by Kirch, in Berlin, who has the following entry in his
+       diary for Saturday, June 29, 1721:&mdash;"I found Venus in a
+       region where the sky was not very clear. The planet was
+       narrow, and I seemed to see its dark side, though this is
+       almost incredible. The diameter of Venus was 65", and its
+       sickle seemed to tremble in the atmospheric vapors." Again,
+       on March 8th, 1726, he records a similar observation. "We
+       observed Venus with the twenty-six foot telescope. I
+       perceived her dark side, and its edge seemed to describe a
+       smaller circle than that of the light side, as is the case
+       of the moon." This effect is due to irradiation, that is to
+       say, to the glare from a bright surface, giving a deceptive
+       enlargement to its apparent area. He again saw the dark side
+       of the planet in October, 1759, as did Harding at Göttingen,
+       with Herschel's ten-foot reflector, on January 24th, 1806.
+       This latter observer saw it on this occasion stand out
+       against the background of the sky as of a pale ashen green,
+       while on February 28th following, it seemed to him of a pale
+       reddish gray, like the color of the eclipsed moon.</p>
+
+    <p>That the latter body should send to us from her nocturnal
+    shadows sufficient light to be visible is easily explicable,
+    since she is then flooded with earth-light reflected on her
+    from a surface thirteen and one-half times greater than her
+    own, and probably casting on her an illumination transcending
+    our full moonlight in the same proportion. But the secondary
+    light of Venus admits of no such explanation, since earth-light
+    on her surface, diminished by 1/12000th part compared to what
+    it is on that of the moon, would be quite insufficient to
+    <span class="pagenum"><a name="page293"
+       id="page293"></a>[pg 293]</span> render her visible to our
+       eyes. The phenomenon was therefore adduced as an argument
+       for the habitability of the planets by Gruithuisen, of the
+       Munich Observatory, who, writing early in this century,
+       suggested that the ashen light of Venus might be due to
+       general illuminations in celebration by her inhabitants of
+       some periodically recurring festivity, The materials for a
+       flare-up on so grand a scale would, he thought, exist in
+       abundance, as he conjectured the vegetation of our planetary
+       neighbor to be more luxuriant than that of our Brazilian
+       forests. The phosphorescence of the Aphroditean oceans, warm
+       and teeming with life, as they are held to be by Zollner,
+       was advanced as an explanatory hypothesis, with scarcely
+       more plausibility, by Professor Safarik, while others have
+       resorted to the supposition of atmospheric or electrical
+       luminosity producing on a large scale some such display as
+       that of the aurora borealis.</p>
+
+    <p>Professor Vogel, of Berlin, who himself saw part of the
+    night-side of Venus, in its semi-obscurity in November, 1871,
+    ascribed its visibility to a twilight effect caused by a very
+    extensive atmosphere. The light thus transmitted to us by
+    aerial diffusion and giving the ashen light, is reflected
+    sunlight, while that sent by the luminous arc on its edge is
+    direct sunlight, refracted, or bent round to us, from behind
+    the planet. The silver selvedge of the dawn edging the dark
+    limb may consequently be the brightest part of the broken
+    nimbus that then seems to surround her.</p>
+
+    <p>A similar appearance is observed during transits of Venus,
+    when she passes directly between us and the actual solar disk.
+    A silver thread is then seen encircling <span class=
+    "pagenum"><a name="page294"
+       id="page294"></a>[pg 294]</span> that side of the planet
+       which has not yet entered on the face of the sun or "a
+       shadowy nebulous ring," as it was described by Mr.
+       Macdonnell at Eden, surrounds the whole planetary disk when
+       two-thirds of it have passed the solar edge. As it moves off
+       it, the same aureole again becomes visible, testifying to
+       the existence of an atmosphere of considerable extent
+       exterior to the sharply outlined surface ordinarily visible.
+       The shimmering haze of reflected sunlight which perpetually
+       enfolds her is only made apparent to us under exceptional
+       circumstances which cut off some portion of her more
+       immediate light, just as we see the motes in the air
+       illuminated by a candle if we hide the actual flame from our
+       eyes. The perennial twilight which seems to reign over the
+       nocturnal hemisphere of Venus may compensate, perhaps, for
+       the want of a satellite to modify its darkness.</p>
+
+    <p>The great prolongation at other times of the horns of her
+    crescent, so as to embrace almost her entire circumference with
+    a tenuous ring of light, is doubtless due to the same cause, as
+    their visibility should otherwise be limited to a half segment
+    of a circle. The regions thus shining to us are obviously those
+    on which the sun has not yet set, his appearance above the
+    horizon being prolonged, as in our own case, by refraction,
+    though to a much larger extent. The magnitude of the sun's disk
+    as seen from Venus, a third larger than it appears to us, is
+    also adducted by Mr. Proctor in his posthumous work, "The Old
+    and the New Astronomy," edited and completed by Mr. A.C.
+    Ranyard, as an element in extending the illumination of Venus
+    to more than a hemisphere of her surface. As <span class=
+    "pagenum"><a name="page295"
+       id="page295"></a>[pg 295]</span> his diameter there is
+       44-1/4°, a zone of more than 22° wide outside the sunward
+       hemisphere is he thinks illuminated by direct though partial
+       sunlight, the orb being throughout this tract still
+       partially above the horizon.</p>
+
+    <div class="figcenter"
+         style="width:300px;">
+        <a href="images/295.png"><img width="300"
+             src="images/295.png"
+             alt="GEOGRAPHICAL ASPECT OF VENUS." /></a><br />
+        GEOGRAPHICAL ASPECT OF VENUS.
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="page296"
+       id="page296"></a>[pg 296]</span>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/296-1.png"><img width="400"
+             src="images/296-1.png"
+             alt="Stars" /></a>
+    </div>
+
+    <h2>THE STARS</h2>
+
+    <h4>(<span class="sc">From Starland.</span>)</h4>
+
+    <h3>BY SIR ROBERT S. BALL.</h3>
+    <hr class="short" />
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/296-2.png"><img width="200"
+             src="images/296-2.png"
+             alt="Stars" /></a>
+    </div>
+
+    <p>The group of bodies which cluster around our sun forms a
+    little island, so to speak, in the extent of infinite space. We
+    may illustrate this by a map in which we shall endeavor to show
+    the stars placed at their proper relative distances. We first
+    open the compasses one inch, and thus draw a little circle to
+    represent the path of the earth. We are not going to put in all
+    the planets. We take Neptune, the outermost, at once. To draw
+    its path I open the compasses to thirty inches, and draw a
+    circle with that radius. That will do for our solar system,
+    though the comets no doubt will roam beyond these limits. To
+    complete our map we ought of course to put in some stars. There
+    are a hundred million to choose from, and we shall begin with
+    the brightest. It is often called the Dog Star, but astronomers
+    know it better as Sirius. Let us see where it is to be placed
+    on our <span class="pagenum"><a name="page297"
+       id="page297"></a>[pg 297]</span> map. Sirius is beyond
+       Neptune, so it must be outside somewhere. Indeed, it is a
+       good deal further off than Neptune; so I try at the edge of
+       the drawing-board; I have got a method of making a little
+       calculation that I do not intend to trouble you with, but I
+       can assure you that the results it leads me to are quite
+       correct; they show me that this board is not big enough. But
+       could a board which was big enough fit into this lecture
+       theatre? Here, again, I make my little calculations, and I
+       find that there would not be room for a board sufficiently
+       great; in fact, if I put the sun here at one end, with its
+       planets around it? Sirius would be too near on the same
+       scale if it were at the further corner. The board would have
+       to go out through the wall of the theatre, out through
+       London. Indeed, big as London is, it would not be large
+       enough to contain the drawing-board that I should require.
+       It would have to stretch about twenty miles from where we
+       are now assembled. We may therefore dismiss any hope of
+       making a practical map of our system on this scale if Sirius
+       is to have its proper place. Let us, then, take some other
+       star. We shall naturally try with the nearest of all. It is
+       one that we do not know in this part of the world, but those
+       that live in the southern hemisphere are well acquainted
+       with it. The name of this star is Alpha Centauri. Even for
+       this star we should require a drawing three or four miles
+       long if the distance from the earth to the sun is to be
+       taken as one inch. You see what an isolated position our sun
+       and his planets occupy. The members of the family are all
+       close together, and the nearest neighbors are situated at
+       enormous distances. There is a good reason <span class=
+       "pagenum"><a name="page298"
+       id="page298"></a>[pg 298]</span> for this separation. The
+       stars are very pretty and perfectly harmless to us where
+       they are at present situated. They might be very troublesome
+       neighbors if they were very much closer to our system. It is
+       therefore well they are so far off; they would be constantly
+       making disturbances in the sun's family if they were near at
+       hand. Sometimes they would be dragging us into unpleasantly
+       great heat by bringing us too close to the sun, or producing
+       a coolness by pulling us away from the sun, which would be
+       quite as disagreeable.</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>The Stars are Suns.</b></p>
+
+    <p>We are about to discuss one of the grandest truths in the
+    whole of nature. We have had occasion to see that this sun of
+    ours is a magnificent globe immensely larger than the greatest
+    of his planets, while the greatest of these planets is
+    immensely larger than this earth; but now we are to learn that
+    our sun is, indeed, only a star not nearly so bright as many of
+    those which shine over our heads every night. We are
+    comparatively close to the sun, so that we are able to enjoy
+    his beautiful light and cheering heat. Each of those other
+    myriads of stars is a sun, and the splendor of those distant
+    suns is often far greater than that of our own. We are,
+    however, so enormously far from them that they appear dwindled
+    down to insignificance. To judge impartially between our sun or
+    star and such a sun or star as Sirius we should stand halfway
+    between the two; it is impossible to make a fair estimate when
+    we find ourselves situated close to one star and a million
+    times as far from the other. After allowance is made for the
+    imperfections of our point of view, we are <span class=
+    "pagenum"><a name="page299"
+       id="page299"></a>[pg 299]</span> enabled to realize the
+       majestic truth that the sun is no more than a star, and that
+       the other stars are no less than suns. This gives us an
+       imposing idea of the extent and magnificence of the universe
+       in which we are situated. Look lip at the sky at
+       night&mdash;you will see a host of stars; try to think that
+       every one of them is itself a sun. It may probably be that
+       those suns have planets circling round them, but it is
+       hopeless for us to expect to see such planets. Were you
+       standing on one of those stars and looking towards our
+       system, you would not perceive the sun to be the brilliant
+       and gorgeous object that we know so well. If you could see
+       him at all, he would merely seem like a star, not nearly as
+       bright as many of those you can see at night. Even if you
+       had the biggest of telescopes to aid your vision, you could
+       never discern from one of these bodies the planets which
+       surround the sun, no astronomer in the stars could see
+       Jupiter, even if his sight were a thousand times as powerful
+       as any sight or telescope that we know. So minute an object
+       as our earth would, of course, be still more hopelessly
+       beyond the possibility of vision.</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>The Number of the Stars.</b></p>
+
+    <p>To count the stars involves a task which lies beyond the
+    power of man to accomplish. Even without the aid of any
+    telescope, we can see a great multitude of stars from this part
+    of the world. There are also many constellations in the
+    southern hemisphere which never appear above our horizon. If,
+    however, we were to go to the equator, then, by waiting there
+    for a twelve-month, all the stars in the heavens would have
+    been <span class="pagenum"><a name="page300"
+       id="page300"></a>[pg 300]</span> successively exposed to
+       view. An astronomer, Houzeau, with the patience to count
+       them, enumerated about six thousand. This is the naked-eye
+       estimate of the star-population of the heavens; but if
+       instead of relying on unaided vision, you get the assistance
+       of a little telescope, you will be astounded at the enormous
+       multitude of stars which are disclosed.</p>
+
+    <div class="figleft"
+         style="width:400px;">
+        <a href="images/300.jpg"><img width="400"
+             src="images/300.jpg"
+             alt="FIG 1. THE GREAT BEAR AND THE POLE." /></a><br />
+        FIG 1. THE GREAT BEAR AND THE POLE.
+    </div>
+
+    <p>An ordinary opera-glass or binocular is a very useful
+    instrument for looking at the stars in the heavens. If you
+    employ an instrument of this sort, you will be amazed to find
+    that the heavens teem with additional hosts of stars that your
+    unaided vision would never have given you knowledge of. Any
+    part of the sky may be observed; but, just to give an
+    illustration, I shall take one special region, namely, that of
+    the Great Bear (Fig. 1). The seven well-known stars are here
+    shown, four of which form a sort of oblong, while the other
+    three represent the tail. I would like you to make this little
+    experiment. On a fine clear night, count how many stars there
+    are within this oblong; they are all very faint, but you will
+    be able to see a few, and, with good sight, and on a clear
+    night, you may see perhaps ten. Next take your opera-glass and
+    sweep it over the same region; if you will carefully count the
+    stars <span class="pagenum"><a name="page301"
+       id="page301"></a>[pg 301]</span> it shows, you will find
+       fully two hundred; so that the opera-glass has, in this part
+       of the sky, revealed nearly twenty times as many stars as
+       could be seen without its aid. As six thousand stars can be
+       seen by the eye all over the heavens, we may fairly expect
+       that twenty times that number&mdash;that is to say, one
+       hundred and twenty thousand stars&mdash;could be shown by
+       the opera-glass over the entire sky. Let us go a step
+       further, and employ a telescope, the object-glass of which
+       is three inches across. This is a useful telescope to have,
+       and, if a good one, will show multitudes of pleasing
+       objects, though an astronomer would not consider it very
+       powerful. An instrument like this, small enough to be
+       carried in the hand, has been applied to the task of
+       enumerating the stars in the northern half of the sky, and
+       three hundred and twenty thousand stars were counted.
+       Indeed, the actual number that might have been seen with it
+       is considerably greater, for when the astronomer Argelander
+       made this memorable investigation he was unable to reckon
+       many of the stars in localities where they lay very close
+       together. This grand count only extended to half the sky,
+       and, assuming that the other half is as richly inlaid with
+       stars, we see that a little telescope like that we have
+       supposed will, when swept over the heavens, reveal a number
+       of stars which exceeds that of the population of any city in
+       England except London. It exhibits more than one hundred
+       times as many stars as our eyes could possibly reveal.
+       Still, we are only at the beginning of the count; the very
+       great telescopes add largely to the number. There are
+       multitudes of stars which in small instruments
+          <span class="pagenum"><a name="page302"
+       id="page302"></a>[pg 302]</span> we cannot see, but which
+       are distinctly visible from our great observatories. That
+       telescope would be still but a comparatively small one which
+       would show as many stars in the sky as there are people
+       living in the mighty city of London; and with the greatest
+       instruments, the tale of stars has risen to a number far
+       greater than that of the entire population of Great
+       Britain.</p>
+
+    <p>In addition to those stars which the largest telescopes show
+    us, there are myriads which make their presence evident in a
+    wholly different way. It is only in quite recent times that an
+    attempt has been made to develop fully the powers of
+    photography in representing the celestial objects. On a
+    photographic plate which has been exposed to the sky in a great
+    telescope the stars are recorded by thousands. Many of these
+    may, of course, be observed with a good telescope, but there
+    are not a few others which no one ever saw in a telescope,
+    which apparently no one ever could see, though the photograph
+    is able to show them. We do not, however, employ a camera like
+    that which the photographer uses who is going to take your
+    portrait. The astronomer's plate is put into his telescope, and
+    then the telescope is turned towards the sky. On that plate the
+    stars produce their images, each by its own light. Some of
+    these images are excessively faint, but we give a very long
+    exposure of an hour or two hours; sometimes as much as four
+    hours' exposure is given to a plate so sensitive that a mere
+    fraction of a second would sufficiently expose it during the
+    ordinary practice of taking a photograph in daylight. We thus
+    afford sufficient time to enable the fainter objects to
+    indicate their presence <span class="pagenum"><a name="page303"
+       id="page303"></a>[pg 303]</span> upon the sensitive film.
+       Even with an exposure of a single hour a picture exhibiting
+       sixteen thousand stars has been taken by Mr. Isaac Roberts,
+       of Liverpool. Yet the portion of the sky which it represents
+       is only one ten-thousandth part of the entire heavens. It
+       should be added that the region which Mr. Roberts has
+       photographed is furnished with stars in rather exceptional
+       profusion.</p>
+
+    <p>Here, at last, we have obtained some conception of the
+    sublime scale on which the stellar universe is constructed. Yet
+    even these plates cannot represent all the stars that the
+    heavens contain. We have every reason for knowing that with
+    larger telescopes, with more sensitive plates, with more
+    prolonged exposures, ever fresh myriads of stars will be
+    brought within our view.</p>
+
+    <p>You must remember that every one of these stars is truly a
+    sun, a lamp, as it were, which doubtless gives light to other
+    objects in its neighborhood as our sun sheds light upon this
+    earth and the other planets. In fact, to realize the glories of
+    the heavens you should try to think that the brilliant points
+    you see are merely the luminous points of the otherwise
+    invisible universe.</p>
+
+    <p>Standing one fine night on the deck of a Cunarder we passed
+    in open ocean another great Atlantic steamer. The vessel was
+    near enough for us to see not only the light from the mast-head
+    but also the little beams from the several cabin ports; and we
+    could see nothing of the ship herself. Her very existence was
+    only known to us by the twinkle of these lights. Doubtless her
+    passengers could see, and did see, the similar lights from our
+    own vessel, and they probably drew the correct inference that
+    these lights indicated a great ship. <span class=
+    "pagenum"><a name="page304"
+       id="page304"></a>[pg 304]</span> Consider the multiplicity
+       of beings and objects in a ship: the captain and the crew,
+       the passengers, the cabins, the engines, the boats, the
+       rigging, and the stores. Think of all the varied interests
+       there collected and then reflect that out on the ocean, at
+       night, the sole indication of the existence of this
+       elaborate structure was given by the few beams of light that
+       happened to radiate from it. Now raise your eyes to the
+       stars; there are the twinkling lights. We cannot see what
+       those lights illuminate, we can only conjecture what untold
+       wealth of non-luminous bodies may also lie in their
+       vicinity; we may, however, feel certain that just as the few
+       gleaming lights from a ship are utterly inadequate to give a
+       notion of the nature and the contents of an Atlantic
+       steamer, so are the twinkling stars utterly inadequate to
+       give even the faintest conception of the extent and the
+       interest of the universe. We merely see self-luminous
+       bodies, but of the multitudes of objects and the elaborate
+       systems of which these bodies are only the conspicuous
+       points we see nothing and we know very little. We are,
+       however, entitled to infer from an examination of our own
+       star&mdash;the sun&mdash;and of the beautiful system by
+       which it is surrounded, that these other suns may be also
+       splendidly attended. This is quite as reasonable a
+       supposition as that a set of lights seen at night on the
+       Atlantic Ocean indicates the existence of a fine ship.</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>The Clusters of Stars.</b></p>
+
+    <p>On a clear night you can often see, stretching across the
+    sky, a track of faint light, which is known to astronomers as
+    the "Milky Way." It extends below the <span class=
+    "pagenum"><a name="page305"
+       id="page305"></a>[pg 305]</span> horizon, and then round the
+       earth to form a girdle about the heavens. When we examine
+       the Milky Way with a telescope we find, to our amazement,
+       that it consists of myriads of stars, so small and so faint
+       that we are not able to distinguish them individually; we
+       merely see the glow produced from their collective rays.
+       Remembering that our sun is a star, and that the Milky Way
+       surrounds us, it would almost seem as if our sun were but
+       one of the host of stars which form this cluster.</p>
+
+    <p>There are also other clusters of stars, some of which are
+    exquisitely beautiful telescopic spectacles. I may mention a
+    celebrated pair of these objects which lies in the
+    constellation of Perseus. The sight of them in a great
+    telescope is so imposing that no one who is fit to look through
+    a telescope could resist a shout of wonder and admiration when
+    first they burst on his view. But there are other clusters.
+    Here is a picture of one which is known as the "Globular
+    Cluster in the Centaur" (Fig. 2). It consists of a ball of
+    stars, so far off that, however large these several suns may
+    actually be, they have dwindled down to extremely small points
+    of light. A homely illustration may serve to show the
+    appearance which a globular cluster presents in a good
+    telescope. I take a pepper-caster, and on a sheet of
+    <span class="pagenum"><a name="page306"
+       id="page306"></a>[pg 306]</span> white paper I begin to
+       shake out the pepper until there is a little heap at the
+       centre and other grains are scattered loosely about. Imagine
+       that every one of those grains of pepper was to be
+       transformed into a tiny electric light, and then you have
+       some idea of what a cluster of stars would look like when
+       viewed through a telescope of sufficient power. There are
+       multitudes of such groups scattered through the depths of
+       space. They require our biggest telescopes to show them
+       adequately. We have seen that our sun is a star, being only
+       one of a magnificent cluster that forms the Milky Way. We
+       have also seen that there are other groups scattered through
+       the length and depth of space. It is thus we obtain a notion
+       of the rank which our earth holds in the scheme of things
+       celestial.</p>
+
+    <div class="figright"
+         style="width:300px;">
+        <a href="images/305.png"><img width="300"
+             src="images/305.png"
+             alt=
+           "FIG. 2. GLOBULAR CLUSTER IN THE CENTAUR." /></a><br />
+        FIG. 2. GLOBULAR CLUSTER IN THE CENTAUR.
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p><b>The Rank of the Earth as a Globe in Space.</b></p>
+
+    <p>Let me give an illustration with the view of explaining more
+    fully the nature of the relation which the earth bears to the
+    other globes which abound through space, and you must allow me
+    to draw a little upon my imagination. I shall suppose that the
+    mails of our country extend not only over this globe, but that
+    they also communicate with other worlds; that postal
+    arrangements exist between Mars and the earth, between the sun
+    and Orion&mdash;in fact, everywhere throughout the whole extent
+    of the universe. We shall consider how our letters are to be
+    addressed. Let us take the case of Mr. John Smith, merchant,
+    who lives at 1001, Piccadilly; and let us suppose that Mr. John
+    Smith's business transactions are of such an extensive nature
+    that they reach not only all over this globe, but away
+    throughout space. <span class="pagenum"><a name="page307"
+       id="page307"></a>[pg 307]</span> I shall suppose that the
+       firm has a correspondent residing&mdash;let us say in the
+       constellation of the Great Bear; and when this man of
+       business wants to write to Mr. Smith from these remote
+       regions, what address must he put upon the letter, so that
+       the Postmaster-General of the universe shall make no mistake
+       about its delivery? He will write as follows:&mdash;</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p>MR. JOHN SMITH,</p>
+
+            <p class="i4">1001 Piccadilly,</p>
+
+            <p class="i8">London,</p>
+
+            <p class="i12">England,</p>
+
+            <p class="i16">Europe,</p>
+
+            <p class="i20">Earth,</p>
+
+            <p class="i24">Near the Sun,</p>
+
+            <p class="i28">Milky Way,</p>
+
+            <p class="i32">The Universe.</p>
+        </div>
+    </div>
+
+    <p>Let us now see what the several lines of this address mean.
+    Of course we put down the name of Mr. John Smith in the first
+    line, and then we will add "1001 Piccadilly" for the second;
+    but as the people in the Great Bear are not likely to know
+    where Piccadilly is, we shall add "London" underneath. As even
+    London itself cannot be well known everywhere, it is better to
+    write "England." This would surely find Mr. John Smith from any
+    post-office on this globe. From other globes, however, the
+    supreme importance of England may not be so immediately
+    recognized, and therefore it is as well to add another line,
+    "Europe." This ought to be sufficient, I think, for any
+    post-office in the solar system. Europe is big enough to be
+    visible from Mars or Venus, and should be known to the
+    post-office people there, just as we know and have names for
+    the continents on Mars. But further away there might be a
+    <span class="pagenum"><a name="page308"
+       id="page308"></a>[pg 308]</span> little difficulty; from
+       Uranus and Neptune the different regions on our earth can
+       never have been distinguished, and therefore we must add
+       another line to indicate the particular globe of the solar
+       system which contains Europe. Mark Twain tells us that there
+       was always one thing in astronomy which specially puzzled
+       him, and that was to know how we found out the names of the
+       stars. We are, of course, in hopeless ignorance of the name
+       by which this earth is called among other intelligent beings
+       elsewhere who can see it. I can only adopt the title of
+       "Earth," and therefore I add this line. Now our address is
+       so complete that from anywhere in the solar
+       system&mdash;from Mercury, from Jupiter, or
+       Neptune&mdash;there ought to be no mistake about the letter
+       finding its way to Mr. John Smith. But from his
+       correspondent in the Great Bear this address would be still
+       incomplete; they cannot see our earth from there, and even
+       the sun himself only looks like a small star&mdash;like one,
+       in fact, of thousands of stars elsewhere. However, each star
+       can be distinguished, and our sun may, for instance, be
+       recognized from the Great Bear by some designation. We shall
+       add the line "Near the Sun," and then I think that from this
+       constellation, or from any of the other stars around us, the
+       address of Mr. John Smith may be regarded as complete. But
+       Mr. Smith's correspondence may be still wider. He may have
+       an agent living in the cluster of Perseus or on some other
+       objects still fainter and more distant; then "Near the Sun"
+       is utterly inadequate as a concluding line to the address,
+       for the sun, if it can be seen at all from thence, will be
+       only of the significance of an excessively minute star, no
+       more to be <span class="pagenum"><a name="page309"
+       id="page309"></a>[pg 309]</span> designated by a special
+       name than are each of the several leaves on the trees of a
+       forest. What this distant correspondent will be acquainted
+       with is not the earth or the sun but only the cluster of
+       stars among which the sun is but a unit. Again we use our
+       own name to denote the cluster, and we call it the "Milky
+       Way." When we add this line, we have made the address of Mr.
+       John Smith as complete as circumstances will permit. I think
+       a letter posted to him anywhere ought to reach its
+       destination. To perfect it, however, we will finish up with
+       one line more&mdash;"The Universe."</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>The Distances of the Stars.</b></p>
+
+    <p>I must now tell you something about the distances of the
+    stars. I shall not make the attempt to explain fully how
+    astronomers make such measurements, but I will give you some
+    notion of how it is done. You may remember I showed you how we
+    found the distance of a globe that was hung from the ceiling.
+    The principle of the method for finding the distance of a star
+    is somewhat similar, except that we make the two observations
+    not from the two ends of a table, not even from opposite sides
+    of the earth, but from two opposite points on the earth's
+    orbit, which are therefore at a distance of one hundred and
+    eighty-six million miles. Imagine that on Midsummer Day, when
+    standing on the earth here, I measure with a piece of card the
+    angle between the star and the sun. Six months later, on
+    Midwinter Day, when the earth is at the opposite point of its
+    orbit, I again measure the angle between the same star and the
+    sun, and we can now determine the star's distance by making a
+    triangle. I draw a line a foot <span class=
+       "pagenum"><a name="page310"
+       id="page310"></a>[pg 310]</span> long, and we will take this
+       foot to represent one hundred and eighty-six million miles,
+       the distance between the two stations; then placing the
+       cards at the corners, I rule the two sides and complete the
+       triangle, and the star must be at the remaining corner; then
+       I measure the sides of the triangle, and how many feet they
+       contain, and recollecting that each foot corresponds to one
+       hundred and eighty-six million miles, we discover the
+       distance of the star. If the stars were comparatively near
+       us, the process would be a very simple one; but,
+       unfortunately, the stars are so extremely far off that this
+       triangle, even with a base of only one foot, must have its
+       sides many miles long. Indeed, astronomers will tell you
+       that there is no more delicate or troublesome work in the
+       whole of their science than that of discovering the distance
+       of a star.</p>
+
+    <p>In all such measurements we take the distance from the earth
+    to the sun as a conveniently long measuring-rod, whereby to
+    express the results. The nearest stars are still hundreds of
+    thousands of times as far off as the sun. Let us ponder for a
+    little on the vastness of these distances. We shall first
+    express them in miles. Taking the sun's distance to be
+    ninety-three million miles, then the distance of the nearest
+    fixed star is about twenty millions of millions of
+    miles&mdash;that is to say, we express this by putting down a 2
+    first, and then writing thirteen ciphers after it. It is, no
+    doubt, easy to speak of such figures, but it is a very
+    different matter when we endeavor to imagine the awful
+    magnitude which such a number indicates. I must try to give
+    some illustrations which will enable you to form a notion of
+    it. At first I was going to ask you to try and
+          <span class="pagenum"><a name="page311"
+       id="page311"></a>[pg 311]</span> count this number, but when
+       I found it would require at least three hundred thousand
+       years, counting day and night without stopping, before the
+       task was over, it became necessary to adopt some other
+       method.</p>
+
+    <p>When on a visit in Lancashire I was once kindly permitted to
+    visit a cotton mill, and I learned that the cotton yarn there
+    produced in a single day would be long enough to wind round
+    this earth twenty-seven times at the equator. It appears that
+    the total production of cotton yarn each day in all the mills
+    together would be on the average about one hundred and
+    fifty-five million miles. In fact, if they would only spin
+    about one-fifth more, we could assert that Great Britain
+    produced enough cotton yarn every day to stretch from the earth
+    to the sun and back again! It is not hard to find from these
+    figures how long it would take for all the mills in Lancashire
+    to produce a piece of yarn long enough to reach from our earth
+    to the nearest of the stars. If the spinners worked as hard as
+    ever they could for a year, and if all the pieces were then
+    tied together, they would extend to only a small fraction of
+    the distance; nor if they worked for ten years, or for twenty
+    years, would the task be fully accomplished. Indeed, upwards of
+    four hundred years would be necessary before enough cotton
+    could be grown in America and spun in this country to stretch
+    over a distance so enormous. All the spinning that has ever yet
+    been done in the world has not formed a long enough thread!</p>
+
+    <p>There is another way in which we can form some notion of the
+    immensity of these sidereal distances. You will recollect that,
+    when we were speaking of Jupiter's moons, I told you of the
+    beautiful discovery <span class="pagenum"><a name="page312"
+       id="page312"></a>[pg 312]</span> which their eclipses
+       enabled astronomers to make. It was thus found that light
+       travels at the enormous speed of about one hundred and
+       eighty-five thousand miles per second. It moves so quickly
+       that within a single second a ray would flash two hundred
+       times from London to Edinburgh and back again.</p>
+
+    <p>We said that a meteor travels one hundred times as swiftly
+    as a rifle-bullet; but even this great speed seems almost
+    nothing when compared with the speed of light, which is ten
+    thousand times as great. Suppose some brilliant outbreak of
+    light were to take place in a distant star&mdash;an outbreak
+    which would be of such intensity that the flash from it would
+    extend far and wide throughout the universe. The light would
+    start forth on its voyage with terrific speed. Any neighboring
+    star which was at a distance of less than one hundred and
+    eighty-five thousand miles would, of course, see the flash
+    within a second after it had been produced. More distant bodies
+    would receive the intimation after intervals of time
+    proportioned to their distances. Thus, if a body were one
+    million miles away, the light would reach it in from five to
+    six seconds, while over a distance as great as that which
+    separates the earth from the sun the news would be carried in
+    about eight minutes. We can calculate how long a time must
+    elapse ere the light shall travel over a distance so great as
+    that between the star and our earth. You will find that from
+    the nearest of the stars the time required for the journey will
+    be over three years. Ponder on all that this involves. That
+    outbreak in the star might be great enough to be visible here,
+    but we could never become aware of it till three years after
+    <span class="pagenum"><a name="page313"
+       id="page313"></a>[pg 313]</span> it had happened. When we
+       are looking at such a star to-night we do not see it as it
+       is at present, for the light that is at this moment entering
+       our eyes has travelled so far that it has been three years
+       on the way. Therefore, when we look at the star now we see
+       it as it was three years previously. In fact, if the star
+       were to go out altogether, we might still continue to see it
+       twinkling for a period of three years longer, because a
+       certain amount of light was on its way to us at the moment
+       of extinction, and so long as that light keeps arriving
+       here, so long shall we see the star showing as brightly as
+       ever. When, therefore, you look at the thousands of stars in
+       the sky to-night, there is not one that you see as it is
+       now, but as it was years ago.</p>
+
+    <p>I have been speaking of the stars that are nearest to us,
+    but there are others much farther off. It is true we cannot
+    find the distances of these more remote objects with any degree
+    of accuracy, but we can convince ourselves how great that
+    distance is by the following reasoning. Look at one of the
+    brightest stars. Try to conceive that the object was carried
+    away further into the depths of space, until it was ten times
+    as far from us as it is at present, it would still remain
+    bright enough to be recognized in quite a small telescope; even
+    if it were taken to one hundred times its original distance it
+    would not have withdrawn from the view of a good telescope;
+    while if it retreated one thousand times as far as it was at
+    first it would still be a recognizable point in our mightiest
+    instruments. Among the stars which we can see with our
+    telescopes, we feel confident there must be many from which the
+    light has expended hundreds of years, or even thousands of
+    years, <span class="pagenum"><a name="page314"
+       id="page314"></a>[pg 314]</span> on the journey. When,
+       therefore, we look at such objects, we see them, not as they
+       are now, but as they were ages ago; in fact, a star might
+       have ceased to exist for thousands of years, and still be
+       seen by us every night as a twinkling point in our great
+       telescopes.</p>
+
+    <p>Remembering these facts, you will, I think, look at the
+    heavens with a new interest. There is a bright star, Vega, or
+    Alpha Lyræ, a beautiful gem, so far off that the light from it
+    which now reaches our eyes started before many of my audience
+    were born. Suppose that there are astronomers residing on
+    worlds amid the stars, and that they have sufficiently powerful
+    telescopes to view this globe, what do you think they would
+    observe? They will not see our earth as it is at present; they
+    will see it as it was years (and sometimes many years) ago.
+    There are stars from which if England could now be seen, the
+    whole of the country would be observed at this present moment
+    to be in a great state of excitement at a very auspicious
+    event. Distant astronomers might notice a great procession in
+    London, and they could watch the coronation of a youthful queen
+    amid the enthusiasm of a nation. There are other stars still
+    further, from which, if the inhabitants had good enough
+    telescopes, they would now see a mighty battle in progress not
+    far from Brussels. One splendid army could be beheld hurling
+    itself time after time against the immovable ranks of the
+    other. They would not, indeed, be able to hear the
+    ever-memorable "Up, Guards, and at them!" but there can be no
+    doubt that there are stars so far away that the rays of light
+    which started from the earth on the day of the battle of
+    Waterloo are only just arriving there. Further off
+          <span class="pagenum"><a name="page315"
+       id="page315"></a>[pg 315]</span> still, there are stars from
+       which a bird's-eye view could be taken at this very moment
+       of the signing of Magna Charta. There are even stars from
+       which England, if it could be seen at all, would now appear,
+       not as the great England we know, but as a country covered
+       by dense forests, and inhabited by painted savages, who
+       waged incessant war with wild beasts that roamed through the
+       island. The geological problems that now puzzle us would be
+       quickly solved could we only go far enough into space and
+       had we only powerful enough telescopes. We should then be
+       able to view our earth through the successive epochs of past
+       geological time; we should be actually able to see those
+       great animals whose fossil remains are treasured in our
+       museums tramping about over the earth's surface, splashing
+       across its swamps, or swimming with broad flippers through
+       its oceans. Indeed, if we could view our own earth reflected
+       from mirrors in the stars, we might still see Moses crossing
+       the Red Sea, or Adam and Eve being expelled from Eden.</p>
+
+    <p>So important is the subject of star distance that I am
+    tempted to give one more illustration in order to bring before
+    you some conception of how vast such distances are. I shall
+    take, as before, the nearest of the stars so far as known to
+    us, and I hope to be forgiven for taking an illustration of a
+    practical and a commercial kind instead of one more purely
+    scientific. I shall suppose that a railway is about to be made
+    from London to Alpha Centauri. The length of that railway, of
+    course, we have already stated: it is twenty billions of miles.
+    So I am now going to ask your attention to the simple question
+    as to the fare which it would be reasonable to
+          <span class="pagenum"><a name="page316"
+       id="page316"></a>[pg 316]</span> charge for the journey. We
+       shall choose a very cheap scale on which to compute the
+       price of a ticket. The parliamentary rate here is, I
+       believe, a penny for every mile. We will make our
+       interstellar railway fares much less even than this; we
+       shall arrange to travel at the rate of one hundred miles for
+       every penny. That, surely, is moderate enough. If the
+       charges were so low that the journey from London to
+       Edinburgh only cost fourpence, then even the most
+       unreasonable passenger would be surely contented. On these
+       terms how much do you think the fare from London to this
+       star ought to be? I know of one way in which to make our
+       answer intelligible. There is a National Debt with which
+       your fathers are, unhappily, only too well acquainted; you
+       will know quite enough about it yourselves in those days
+       when you have to pay income tax. This debt is so vast that
+       the interest upon it is about sixty thousand pounds a day,
+       the whole amount of the National Debt being six hundred and
+       thirty-eight millions of pounds.</p>
+
+    <p>If you went to the booking-office with the whole of this
+    mighty sum in your pocket&mdash;but stop a moment; could you
+    carry it in your pocket? Certainly not, if it were in
+    sovereigns. You would find that after you had as many
+    sovereigns as you could conveniently carry there would still be
+    some left&mdash;so many, indeed, that it would be necessary to
+    get a cart to help you on with the rest. When the cart had as
+    great a load of sovereigns as the horse could draw there would
+    be still some more, and you would have to get another cart; but
+    ten carts, twenty carts, fifty carts, would not be enough. You
+    would want five thousand of these before you <span class=
+    "pagenum"><a name="page317"
+       id="page317"></a>[pg 317]</span> would be able to move off
+       towards the station with your money. When you did get there
+       and asked for a ticket at the rate of one hundred miles for
+       a penny, do you think you would get any change? No doubt
+       some little time would be required to count the money, but
+       when it was counted the clerk would tell you that there was
+       not enough&mdash;that he must have nearly two hundred
+       millions of pounds more.</p>
+
+    <p>That will give some notion of the distance of the nearest
+    star, and we may multiply it by ten, by one hundred, and even
+    by one thousand, and still not attain to the distance of some
+    of the more remote stars that the telescope shows us.</p>
+
+    <p>On account of the immense distances of the stars we can only
+    perceive them to be mere points of light. We can never see a
+    star to be a globe with marks on it like the moon, or like one
+    of the planets&mdash;in fact, the better the telescope the
+    smaller does the star seem, though, of course, its brightness
+    is increased with every addition to the light-grasping power of
+    the instrument.</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>The Brightness and Color of Stars.</b></p>
+
+    <p>Another point to be noticed is the arrangement of stars in
+    classes, according to their lustre. The brightest stars, of
+    which there are about twenty, are said to be of the first
+    magnitude. Those just inferior to the first magnitude are
+    ranked as the second; and those just lower than the second are
+    estimated as the third; and so on. The smallest points that
+    your unaided eyes will show you are of about the sixth
+    magnitude. Then the telescope will reveal stars still fainter
+    and fainter, down to what we term the seventeenth or eighteenth
+    <span class="pagenum"><a name="page318"
+       id="page318"></a>[pg 318]</span> magnitudes, or even lower
+       still. The number of stars of each magnitude increases very
+       much in the classes of small ones.</p>
+
+    <div class="figright"
+         style="width:400px;">
+        <a href="images/319.jpg"><img width="400"
+             src="images/319.jpg"
+             alt="FIG. 3. PERSEUS AND ITS NEIGHBORING STARS" /></a>
+
+        <p>FIG. 3. PERSEUS AND ITS NEIGHBORING STARS INCLUDING
+        ALGOL.</p>
+    </div>
+
+    <p>Most of the stars are white, but many are of a somewhat
+    ruddy hue. There are a few telescopic points which are
+    intensely red, some exhibit beautiful golden tints, while
+    others are blue or green.</p>
+
+    <p>There are some curious stars which regularly change their
+    brilliancy. Let me try to illustrate the nature of these
+    variables. Suppose that you were looking at a street gas-lamp
+    from a very long distance, so that it seemed a little twinkling
+    light; and suppose that some one was preparing to turn the
+    gas-cock up and down. Or, better still, imagine a little
+    machine which would act regularly so as to keep the light first
+    of all at its full brightness for two days and a half, and then
+    gradually turn it down until in three or four hours it declines
+    to a feeble glimmer. In this low state the light remains for
+    twenty minutes; then during three or four hours the gas is to
+    be slowly turned on again until it is full. In this condition
+    the light will remain for two days and a half, and then the
+    same series of changes is to recommence. This would be a very
+    odd form of gas-lamp. There would be periods of two days and a
+    half during which it would remain at its full; these would be
+    separated by intervals of about seven hours, when the gradual
+    turning down and turning up again would be in progress.</p>
+
+    <p>The imaginary gas-lamp is exactly paralleled by a star
+    Algol, in the constellation of Perseus (Fig. 3), which goes
+    through the series of changes I have indicated. Ordinarily
+    speaking, it is a bright star of the <span class=
+    "pagenum"><a name="page319"
+       id="page319"></a>[pg 319]</span> second magnitude, and,
+       whatever be the cause, the star performs its variations with
+       marvellous uniformity. In fact, Algol has always arrested
+       the attention of those who observed the heavens, and in
+       early times was looked on as the eye of a demon. There are
+       many other stars which also change their brilliancy. Most of
+       them require much longer periods than Algol, and sometimes a
+       new star which nobody has ever seen before will suddenly
+       kindle into brilliancy. It is now known that the bright star
+       Algol is attended by a dark companion. This dark star
+       sometimes comes between Algol and the observer and cuts off
+       the light. Thus it is that the diminution of brightness is
+       produced.</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>Double Stars.</b></p>
+
+    <p>Whenever you have a chance of looking at the heavens through
+    a telescope, you should ask to be shown what is called <i>a
+    double star</i>. There are many stars in the heavens which
+    present no remarkable appearance to the unaided eye, but which
+    a good telescope at once shows to be of quite a complex nature.
+    <span class="pagenum"><a name="page320"
+       id="page320"></a>[pg 320]</span> These are what we call
+       double stars, in which two quite distinct stars are placed
+       so close together that the unaided eye is unable to separate
+       them. Under the magnifying power of the telescope, however,
+       they are seen to be distinct. In order to give some notion
+       of what these objects are like, I shall briefly describe
+       three of them. The first lies in that best known
+       constellation, the Great Bear. If you look at his tail,
+       which consists of three stars, you will see that near the
+       middle one of the three a small star is situated; we call
+       this little star Alcor, but it is the brighter one near
+       Alcor to which I specially call your attention. The sharpest
+       eye would never suspect that it was composed of two stars
+       placed close together. Even a small telescope will, however,
+       show this to be the case, and this is the easiest and the
+       first observation that a young astronomer should make when
+       beginning to turn a telescope to the heavens. Of course you
+       will not imagine that I mean Alcor to be the second
+       component of the double star; it is the bright star near
+       Alcor which is the double. Here are two marbles, and these
+       marbles are fastened an inch apart. You can see them, of
+       course, to be separate; but if the pair were moved further
+       and further away, then you would soon not be able to
+       distinguish between them, though the actual distance between
+       the marbles had not altered. Look at these two wax tapers
+       which are now lighted; the little flames are an inch apart.
+       You would have to view them from a station a third of a mile
+       away if the distance between the two flames were to appear
+       the same as that between the two components of this double
+       star. Your eye would never be able to discriminate between
+       two <span class="pagenum"><a name="page321"
+       id="page321"></a>[pg 321]</span> lights only an inch apart
+       at so great a distance; a telescope would, however, enable
+       you to do so, and this is the reason why we have to use
+       telescopes to show us double stars.</p>
+
+    <p>You might look at that double star year after year
+    throughout the course of a long life without finding any
+    appreciable change in the relative positions of its components.
+    But we know that there is no such thing as rest in the
+    universe; even if you could balance a body so as to leave it
+    for a moment at rest, it would not stay there, for the simple
+    reason that all the bodies round it in every direction are
+    pulling at it, and it is certain that the pull in one direction
+    will preponderate, so that move it must. Especially is this
+    true in the case of two suns like those forming a double star.
+    Placed comparatively near each other they could not remain
+    permanently in that position; they must gradually draw together
+    and come into collision with an awful crash. There is only one
+    way by which such a disaster could be averted. That is by
+    making one of these stars revolve around the other just as the
+    earth revolves around the sun, or the moon revolves around the
+    earth. Some motion must, therefore, be going on in every
+    genuine double star, whether we have been able to see that
+    motion or not.</p>
+
+    <p>Let us now look at another double star of a different kind.
+    This time it is in the constellation of Gemini. The heavenly
+    twins are called Castor and Pollux. Of these, Castor is a very
+    beautiful double star, consisting of two bright points, a great
+    deal closer together than were those in the Great Bear;
+    consequently a better telescope is required for the purpose of
+    showing them <span class="pagenum"><a name="page322"
+       id="page322"></a>[pg 322]</span> separately. Castor has been
+       watched for many years, and it can be seen that one of these
+       stars is slowly revolving around the other; but it takes a
+       very long time, amounting to hundreds of years, for a
+       complete circuit to be accomplished. This seems very
+       astonishing, but when you remember how exceedingly far
+       Castor is, you will perceive that that pair of stars which
+       appear so close together that it requires a telescope to
+       show them apart must indeed be separated by hundreds of
+       millions of miles. Let us try to conceive our own system
+       transformed into a double star. If we took our outermost
+       planet&mdash;Neptune&mdash;and enlarged him a good deal, and
+       then heated him sufficiently to make him glow like a sun, he
+       would still continue to revolve round our sun at the same
+       distance, and thus a double star would be produced. An
+       inhabitant of Castor who turned his telescope towards us
+       would be able to see the sun as a star. He would not, of
+       course, be able to see the earth, but he might see Neptune
+       like another small star close to the sun. If generations of
+       astronomers in Castor continued their observations of our
+       system, they would find a binary star, of which one
+       component took a century and a half to go round the other.
+       Need we then be surprised that when we look at Castor we
+       observe movements that seem very slow?</p>
+
+    <p>There is often so much diffused light about the bright stars
+    seen in a telescope, and so much twinkling in some states of
+    the atmosphere, that stars appear to dance about in rather a
+    puzzling fashion, especially to one who is not accustomed to
+    astronomical observations. I remember hearing how a gentleman
+    once came to visit an observatory. The astronomer showed him
+    <span class="pagenum"><a name="page323"
+       id="page323"></a>[pg 323]</span> Castor through a powerful
+       telescope as a fine specimen of a double star, and then, by
+       way of improving his little lesson, the astronomer mentioned
+       that one of these stars was revolving around the other. "Oh,
+       yes," said the visitor, "I saw them going round and round in
+       the telescope." He would, however, have had to wait for a
+       few centuries with his eye to the instrument before he would
+       have been entitled to make this assertion.</p>
+
+    <p>Double stars also frequently delight us by giving
+    beautifully contrasted colors. I dare say you have often
+    noticed the red and the green lights that are used on railways
+    in the signal lamps. Imagine one of those red and one of those
+    green lights away far up in the sky and placed close together,
+    then you would have some idea of the appearance that a colored
+    double star presents, though, perhaps, I should add that the
+    hues in the heavenly bodies are not so vividly different as are
+    those which our railway people find necessary. There is a
+    particularly beautiful double star of this kind in the
+    constellation of the Swan. You could make an imitation of it by
+    boring two holes, with a red-hot needle, in a piece of card,
+    and then covering one of these holes with a small bit of the
+    topaz-colored gelatine with which Christmas crackers are made.
+    The other star is to be similarly colored with blue gelatine. A
+    slide made on this principle placed in the lantern gives a very
+    good representation of these two stars on the screen. There are
+    many other colored doubles besides this one; and, indeed, it is
+    noteworthy that we hardly ever find a blue or a green star by
+    itself in the sky; it is always as a member of one of these
+    pairs.</p><span class="pagenum"><a name="page324"
+       id="page324"></a>[pg 324]</span>
+
+    <p>&nbsp;</p>
+
+    <p><b>How We Find What the Stars are Made of.</b></p>
+
+    <p>Here is a piece of stone. If I wanted to know what it was
+    composed of, I should ask a chemist to tell me. He would take
+    it into his laboratory, and first crush it into powder, and
+    then, with his test tubes, and with the liquids which his
+    bottles contain, and his weighing scales, and other apparatus,
+    he would tell all about it; there is so much of this, and so
+    much of that, and plenty of this, and none at all of that. But
+    now, suppose you ask this chemist to tell you what the sun is
+    made of, or one of the stars. Of course, you have not a sample
+    of it to give him; how, then, can he possibly find out anything
+    about it? Well, he can tell you something, and this is the
+    wonderful discovery that I want to explain to you. We now put
+    down the gas, and I kindle a brilliant red light. Perhaps some
+    of those whom I see before me have occasionally ventured on the
+    somewhat dangerous practice of making fire-works. If there is
+    any boy here who has ever constructed sky-rockets, and put the
+    little balls into the top which are to burn with such vivid
+    colors when the explosion takes place, he will know that the
+    substance which tinged that fire red must have been strontium.
+    He will recognize it by the color; because strontium gives a
+    red light which nothing else will give. Here are some of these
+    lightning papers, as they are called; they are very pretty and
+    very harmless; and these, too, give brilliant red flashes as I
+    throw them. The red tint has, no doubt, been produced by
+    strontium also. You see we recognized the substance simply by
+    the color of the light it produced when
+          burning.</p><span class="pagenum"><a name="page325"
+       id="page325"></a>[pg 325]</span>
+
+    <p>Perhaps some of you have tried to make a ghost at Christmas
+    by dressing up in a sheet, and bearing in your hand a ladle
+    blazing with a mixture of common salt and spirits of wine, the
+    effect produced being a most ghastly one. Some mammas will
+    hardly thank me for this suggestion, unless I add that the
+    ghost must walk about cautiously, for otherwise the blazing
+    spirit would be very apt to produce conflagrations of a kind
+    more extensive than those intended. However, by the kindness of
+    Professor Dewar, I am enabled to show the phenomenon on a
+    splendid scale, and also free from all danger. I kindle a vivid
+    flame of an intensely yellow color, which I think the ladies
+    will unanimously agree is not at all becoming to their
+    complexions, while the pretty dresses have lost their variety
+    of colors. Here is a nice bouquet, and yet you can hardly
+    distinguish the green of the leaves from the brilliant colors
+    of the flowers, except by trifling differences of shade. Expose
+    to this light a number of pieces of variously colored ribbon,
+    pink and red and green and blue, and their beauty is gone; and
+    yet we are told that this yellow is a perfectly pure color; in
+    fact, the purest color that can be produced. I think we have to
+    be thankful that the light which our good sun sends us does not
+    possess purity of that description. There is one substance
+    which will produce that yellow light; it is a curious metal
+    called sodium&mdash;a metal so soft that you can cut it with a
+    knife, and so light that it will float on water; while, still
+    more strange, it actually takes fire the moment it is dropped
+    on the water. It is only in a chemical laboratory that you will
+    be likely to meet with the actual metallic sodium, yet in other
+    forms the <span class="pagenum"><a name="page326"
+       id="page326"></a>[pg 326]</span> substance is one of the
+       most abundant in nature. Indeed, common salt is nothing but
+       sodium closely united with a most poisonous gas, a few
+       respirations of which would kill you. But this strange metal
+       and this noxious gas, when united, become simply the salt
+       for our eggs at breakfast. This pure yellow light, wherever
+       it is seen, either in the flame of spirits of wine mixed
+       with salt or in that great blaze at which we have been
+       looking, is characteristic of sodium. Wherever you see that
+       particular kind of light, you know that sodium must have
+       been present in the body from which it came.</p>
+
+    <p>We have accordingly learned to recognize two substances,
+    namely, strontium and sodium, by the different lights which
+    they give out when burning. To these two metals we may add a
+    third. Here is a strip of white metallic ribbon. It is called
+    magnesium. It seems like a bit of tin at the first glance, but
+    indeed it is a very different substance from tin; for, look,
+    when I hold it in the spirit-lamp, the strip of metal
+    immediately takes fire, and burns with a white light so
+    dazzling that it pales the gas-flames to insignificance. There
+    is no other substance which will, when kindled, give that
+    particular kind of light which we see from magnesium. I can
+    recommend this little experiment as quite suitable for trying
+    at home; you can buy a bit of magnesium ribbon for a trifle at
+    the opticians; it cannot explode or do any harm, nor will you
+    get into any trouble with the authorities provided you hold it
+    when burning over a tray or a newspaper, so as to prevent the
+    white ashes from falling on the carpet.</p>
+
+    <p>There are, in nature, a number of simple bodies called
+    <span class="pagenum"><a name="page327"
+       id="page327"></a>[pg 327]</span> elements. Every one of
+       these, when ignited under suitable conditions, emits a light
+       which belongs to it alone, and by which it can be
+       distinguished from every other substance. I do not say that
+       we can try the experiments in the simple way I have here
+       indicated. Many of the materials will yield light which will
+       require to be studied by much more elaborate artifices than
+       those which have sufficed for us. But you will see that the
+       method affords a means of finding out the actual substances
+       present in the sun or in the stars. There is a practical
+       difficulty in the fact that each of the heavenly bodies
+       contains a number of different elements; so that in the
+       light it sends us the hues arising from distinct substances
+       are blended into one beam. The first thing to be done is to
+       get some way of splitting up a beam of light, so as to
+       discover the components of which it is made. You might have
+       a skein of silks of different hues tangled together, and
+       this would be like the sunbeam as we receive it in its
+       unsorted condition. How shall we untangle the light from the
+       sun or a star? I will show you by a simple experiment. Here
+       is a beam from the electric light; beautifully white and
+       bright, is it not? It looks so pure and simple, but yet that
+       beam is composed of all sorts of colors mingled together, in
+       such proportions as to form white light. I take a
+       wedge-shaped piece of glass called a prism, and when I
+       introduce it into the course of the beam, you see the
+       transformation that has taken place (Fig. 4). Instead of the
+       white light you have now all the colors of the
+       rainbow&mdash;red, orange, yellow, green, blue, indigo,
+       violet, marked by their initial letters in the figure. These
+       colors are very beautiful, but they are transient, for the
+       <span class="pagenum"><a name="page328"
+       id="page328"></a>[pg 328]</span> moment we take away the
+       prism they all unite again to form white light. You see what
+       the prism has done; it has bent all the light in passing
+       through it; but it is more effective in bending the blue
+       than the red, and consequently the blue is carried away much
+       further than the red. Such is the way in which we study the
+       composition of a heavenly body. We take a beam of its light,
+       we pass it through a prism, and immediately it is separated
+       into its components; then we compare what we find with the
+       lights given by the different elements, and thus we are
+       enabled to discover the substances which exist in the
+       distant object whose light we have examined. I do not mean
+       to say that the method is a simple one; all I am endeavoring
+       to show is a general outline of the way in which we have
+       discovered the materials present in the stars. The
+       instrument that is employed for this purpose is called the
+       spectroscope. And perhaps you may remember that name by
+       these lines, which I have heard from an astronomical
+       friend:&mdash;</p>
+
+    <div class="poem">
+        <div class="stanza">
+            <p>"Twinkle, twinkle, little star,</p>
+
+            <p>Now we find out what you are,</p>
+
+            <p>When unto the midnight sky,</p>
+
+            <p>We the spectroscope apply."</p>
+        </div>
+    </div>
+
+    <div class="figright"
+         style="width:400px;">
+        <a href="images/328.jpg"><img width="400"
+             src="images/328.jpg"
+             alt="FIG. 4. HOW A RAY OF LIGHT IS SPLIT UP." /></a><br />
+        FIG. 4. HOW A RAY OF LIGHT IS SPLIT UP.
+    </div><span class="pagenum"><a name="page329"
+       id="page329"></a>[pg 329]</span>
+
+    <p>I am sure it will interest everybody to know that the
+    elements which the stars contain are not altogether different
+    from those of which the earth is made. It is true there may be
+    substances in the stars of which we know nothing here; but it
+    is certain that many of the most common elements on the earth
+    are present in the most distant bodies. I shall only mention
+    one, the metal iron. That useful substance has been found in
+    some of the stars which lie at almost incalculable distances
+    from the earth.</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>The Nebulæ.</b></p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/330-1.png"><img width="300"
+             src="images/330-1.png"
+             alt="FIG. 5. A GREAT REFLECTING TELESCOPE." /></a><br />
+        FIG. 5. A GREAT REFLECTING TELESCOPE.
+    </div>
+
+    <p>In drawing towards the close of these lectures I must say a
+    few words about some dim and mysterious objects to which we
+    have not yet alluded. They are what are called nebulæ, or
+    little clouds; and in one sense they are justly called little,
+    for each of them occupies but a very small spot in the sky as
+    compared with that which would be filled by an ordinary cloud
+    in our air. The nebulæ are, however, objects of the most
+    stupendous proportions. Were our earth and thousands of
+    millions of bodies quite as big all put together, they would
+    not be nearly so great as one of these nebulæ. Astronomers
+    reckon up the various nebulæ by thousands, but I must add that
+    most of them are apparently faint and uninteresting. A nebula
+    is sometimes liable to be mistaken for a comet. The comet is,
+    as I have already explained, at once distinguished by the fact
+    that it is moving and changing its appearance from hour to
+    hour, while scores of years elapse without changes in the
+    aspect or position of a nebula. The most powerful telescopes
+    are employed in observing <span class="pagenum"><a name=
+    "page330"
+       id="page330"></a>[pg 330]</span> these faint objects. I take
+       this opportunity of showing a picture of an instrument
+       suitable for such observations. It is the great reflector of
+       the Paris Observatory (Fig. 5).</p>
+
+    <div class="figright"
+         style="width:350px;">
+        <a href="images/330-2.jpg"><img width="350"
+             src="images/330-2.jpg"
+             alt=
+           "FIG. 6. THE RING NEBULA IN LYRA, UNDER DIFFERENT TELESCOPIC POWERS." /></a>
+
+        <p>FIG. 6. THE RING NEBULA IN LYRA, UNDER DIFFERENT
+        TELESCOPIC POWERS.</p>
+    </div>
+
+    <p>There are such multitudes of nebulæ that I can only show a
+    few of the more remarkable kinds. In Fig. 6 will be seen
+    pictures of a curious object in the constellation of Lyra seen
+    under different telescopic powers. This is a gigantic ring of
+    luminous gas. To judge of the size of this ring let us suppose
+    that a railway were laid across it, and the train you entered
+    at one side was not to stop until it reached the other side,
+    how long do you think this journey would require? I recollect
+    some time ago a picture in <i>Punch</i> which showed a train
+    about to start from London to Brighton, and the guard walking
+    up and down announcing to the passengers the alarming fact that
+    "this train stops nowhere." An old gentleman was seen
+    <span class="pagenum"><a name="page331"
+       id="page331"></a>[pg 331]</span> vainly gesticulating out of
+       the window and imploring to be let out ere the frightful
+       journey was commenced. In the nebular railway the passengers
+       would almost require such a warning.</p>
+
+    <p>Let the train start at a speed of a mile a minute, you would
+    think, surely, that it must soon cross the ring. But the
+    minutes pass, an hour has elapsed; so the distance must be
+    sixty miles at all events. The hours creep on into days, the
+    days advance into years, and still the train goes on. The years
+    would lengthen out into centuries, and even when the train had
+    been rushing on for a thousand years with an unabated speed of
+    a mile a minute, the journey would certainly not have been
+    completed. Nor do I venture to say what ages must elapse ere
+    the terminus at the other side of the ring nebula would be
+    reached.</p>
+
+    <p>A cluster of stars viewed in a small telescope will often
+    seem like a nebula, for the rays of the stars become blended. A
+    powerful telescope will, however, dispel the illusion and
+    reveal the separate stars. It was, therefore, thought that all
+    the nebulæ might be merely clusters so exceedingly remote that
+    our mightiest instruments failed to resolve them into stars.
+    But this is now known not to be the case. Many of these objects
+    are really masses of glowing gas; such are, for instance, the
+    ring nebulæ, of which I have just spoken, and the form of which
+    I can simulate by a pretty experiment.</p>
+
+    <p>We take a large box with a round hole cut in one face, and a
+    canvas back at the opposite side. I first fill this box with
+    smoke, and there are different ways of doing so. Burning brown
+    paper does not answer <span class="pagenum"><a name="page332"
+       id="page332"></a>[pg 332]</span> well, because the supply of
+       smoke is too irregular and the paper itself is apt to blaze.
+       A little bit of phosphorus set on fire yields copious smoke,
+       but it would be apt to make people cough, and, besides,
+       phosphorus is a dangerous thing to handle incautiously, and
+       I do not want to suggest anything which might be productive
+       of disaster if the experiment was repeated at home. A little
+       wisp of hay, slightly damped and lighted, will safely yield
+       a sufficient supply, and you need not have an elaborate box
+       like this; any kind of old packing-case, or even a bandbox
+       with a duster stretched across its open top and a round hole
+       cut in the bottom, will answer capitally. While I have been
+       speaking, my assistant has kindly filled this box with
+       smoke, and in order to have a sufficient supply, and one
+       which shall be as little disagreeable as possible, he has
+       mixed together the fumes of hydrochloric acid and ammonia
+       from two retorts shown in Fig. 7. A still simpler way of
+       doing the same thing is to put a little common salt in a
+       saucer and pour over it a little oil of vitriol; this is put
+       into the box, and over the floor of the box common
+       smelling-salts is to be scattered. You see there are dense
+       volumes of white smoke escaping from every corner of the
+       box. I uncover the opening and give a push to the canvas,
+       and you see a beautiful ring flying across the room; another
+       ring and another follows. If you were near <span class=
+       "pagenum"><a name="page333"
+       id="page333"></a>[pg 333]</span> enough to feel the ring,
+       you would experience a little puff of wind; I can show this
+       by blowing out a candle which is at the other end of the
+       table. These rings are made by the air which goes into a
+       sort of eddy as it passes through the hole. All the smoke
+       does is to render the air visible. The smoke-ring is indeed
+       quite elastic. If we send a second ring hurriedly after the
+       first, we can produce a collision, and you see each of the
+       two rings remains unbroken, though both are quivering from
+       the effects of the blow. They are beautifully shown along
+       the beam of the electric lamp, or, better still, along a
+       sunbeam.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/332.png"><img width="300"
+             src="images/332.png"
+             alt="FIG. 7. HOW TO MAKE THE SMOKE RINGS." /></a><br />
+        FIG. 7. HOW TO MAKE THE SMOKE RINGS.
+    </div>
+
+    <p>We can make many experiments with smoke-rings. Here, for
+    instance, I take an empty box, so far as smoke is concerned,
+    but air-rings can be driven forth from it, though you cannot
+    see them, but you can feel them even at the other side of the
+    room, and they will, as you see, blow out a candle. I can also
+    shoot invisible air-rings at a column of smoke, and when the
+    missile strikes the smoke it produces a little commotion and
+    emerges on the other side, carrying with it enough of the smoke
+    to render itself visible, while the solid black looking ring of
+    air is seen in the interior. Still more striking is another way
+    of producing these rings, for I charge this box with ammonia,
+    and the rings from it you cannot see. There is a column of the
+    vapor of hydrochloric acid, that also you cannot see; but when
+    the visible ring enters the invisible column, then a sudden
+    union takes place between the vapor of the ammonia and the
+    vapor of the hydrochloric acid; the result is a solid white
+    substance in extremely fine dust which renders the ring
+    instantly visible.</p><span class="pagenum"><a name="page334"
+       id="page334"></a>[pg 334]</span>
+
+    <p>&nbsp;</p>
+
+    <p><b>What the Nebulæ are made of.</b></p>
+
+    <p>There is a fundamental difference between the illumination
+    of these little rings that I have shown you and the great rings
+    in the heavens. I had to illuminate our smoke with the help of
+    the electric light, for, unless I had done so, you would not
+    have been able to see them. This white substance formed by the
+    union of ammonia and hydrochloric acid has, of course, no more
+    light of its own than a piece of chalk; it requires other light
+    falling upon it to make it visible. Were the ring nebula in
+    Lyra composed of this material, we could not see it. The
+    sunlight which illuminates the planets might, of course, light
+    up such an object as the ring, if it wrere comparatively near
+    us; but Lyra is at such a stupendous distance that any light
+    which the sun could send out there would be just as feeble as
+    the light we receive from a fixed star. Should we be able to
+    show our smoke-rings, for instance, if, instead of having the
+    electric light, I merely cut a hole in the ceiling and allowed
+    the feeble twinkle of a star in the Great Bear to shine
+    through? In a similar way the sunbeams would be utterly
+    powerless to effect any illumination of objects in these
+    stellar distances. If the sun were to be extinguished
+    altogether, the calamity would no doubt be a very dire one so
+    far as we are concerned, but the effect on the other celestial
+    bodies (moon and planets excepted) would be of the slightest
+    possible description. All the stars of heaven would continue to
+    shine as before. Not a point in one of the constellations
+    wrould be altered, not a variation in the brightness, not a
+    change in the hue of any star could <span class=
+    "pagenum"><a name="page335"
+       id="page335"></a>[pg 335]</span> be noticed. The thousands
+       of nebulæ and clusters would be absolutely unaltered; in
+       fact, the total extinction of the sun would be hardly
+       remarked in the newspapers published in the Pleiades or in
+       Orion. There might possibly be a little line somewhere in an
+       odd corner to the effect "Mr. So-and-So, our well-known
+       astronomer, has noticed that a tiny star, inconspicuous to
+       the eye, and absolutely of no importance whatever, has now
+       become invisible."</p>
+
+    <p>If, therefore, it be not the sun which lights up this
+    nebula, where else can be the source of its illumination? There
+    can be no other star in the neighborhood adequate to the
+    purpose, for, of course, such an object would be brilliant to
+    us if it were large enough and bright enough to impart
+    sufficient illumination to the nebula. It would be absurd to
+    say that you could see a man's face by the light of a candle
+    while the candle itself was too faint or too distant to be
+    visible. The actual facts are, of course, the other way; the
+    candle might be visible, when it was impossible to discern the
+    face which it lighted.</p>
+
+    <p>Hence we learn that the ring nebula must shine by some light
+    of its own, and now we have to consider how it can be possible
+    for such material to be self-luminous. The light of a nebula
+    does not seem to be like flame; it can, perhaps, be better
+    represented by the pretty electrical experiment with Geissler's
+    tubes. These are glass vessels of various shapes, and they are
+    all very nearly empty, as you will understand when I tell you
+    the way in which they have been prepared. A little gas was
+    allowed into each tube, and then almost all the gas was taken
+    out again, so that only a mere <span class=
+       "pagenum"><a name="page336"
+       id="page336"></a>[pg 336]</span> trace was left. I pass a
+       current of electricity through these tubes, and now you see
+       they are glowing with beautiful colors. The different gases
+       give out lights of different hues, and the optician has
+       exerted his skill so as to make the effect as beautiful as
+       possible. The electricity, in passing through these tubes,
+       heats the gas which they contain, and makes it glow; and
+       just as this gas can, when heated sufficiently, give out
+       light, so does the great nebula, which is a mass of gas
+       poised in space, become visible in virtue of the heat which
+       it contains.</p>
+
+    <p>We are not left quite in doubt as to the constitution of
+    these gaseous nebulæ, for we can submit their light to the
+    prism in the way I explained when we were speaking of the
+    stars. Distant though that ring in Lyra may be, it is
+    interesting to learn that the ingredients from which it is made
+    are not entirely different from substances we know on our
+    earth. The water in this glass, and every drop of water, is
+    formed by the union of two gases, of which one is hydrogen.
+    This is an extremely light material, as you see by a little
+    balloon which ascends so prettily when filled with it. Hydrogen
+    also burns very readily, though the flame is almost invisible.
+    When I blow a jet of oxygen through the hydrogen, I produce a
+    little flame with a very intense heat. For instance, I hold a
+    steel pen in the flame, and it glows and sputters, and falls
+    down in white-hot drops. It is needless to say that, as a
+    constituent of water, hydrogen is one of the most important
+    elements on this earth. It is, therefore, of interest to learn
+    that hydrogen in some form or other is a constituent of the
+    most distant objects in space that the telescope has
+    revealed.</p><span class="pagenum"><a name="page337"
+       id="page337"></a>[pg 337]</span>
+
+    <p>&nbsp;</p>
+
+    <p><b>Photographing the Nebulæ.</b></p>
+
+    <div class="figright"
+         style="width:300px;">
+        <a href="images/337.jpg"><img width="300"
+             src="images/337.jpg"
+             alt="FIG. 8. THE PLEIADES." /></a><br />
+        FIG. 8. THE PLEIADES.
+    </div>
+
+    <p>Of late years we have learned a great deal about nebulæ, by
+    the help which photography has given to us. Look at this group
+    of stars which constitutes that beautiful little configuration
+    known as the Pleiades (Fig. 8). It looks like a miniature
+    representation of the Great Bear; in fact, it would be far more
+    appropriate to call the Pleiades the Little Bear than to apply
+    that title to another quite different constellation, as has
+    unfortunately been done. The Pleiades form a group containing
+    six or seven stars visible to the ordinary eye, though persons
+    endowed with exceptionally good vision can usually see a few
+    more. In an opera-glass the Pleiades becomes a beautiful
+    spectacle, though in a large telescope the stars appear too far
+    apart to make a really effective cluster. When Mr. Roberts took
+    a photograph of the Pleiades he placed a highly sensitive plate
+    in his telescope, and on that plate the Pleiades engraved their
+    picture with their own light. He left the plate exposed for
+    hours, and on developing it not only were the stars seen, but
+    there were also patches of faint light due to the presence of
+    nebulæ. It could not be said that the objects on the plate were
+    fallacious, for another photograph was taken, when the same
+    appearances were reproduced.</p><span class=
+       "pagenum"><a name="page338"
+       id="page338"></a>[pg 338]</span>
+
+    <p>When we look at that pretty group of stars which has
+    attracted admiration during all time, we are to think that some
+    of those stars are merely the bright points in a vast nebula,
+    invisible to our unaided eyes or even to our mighty telescopes,
+    though capable of recording its trace on the photographic
+    plate. Does not this give us a greatly increased notion of the
+    extent of the universe, when we reflect that by photography we
+    are enabled to see much which the mightiest of telescopes had
+    previously failed to disclose?</p>
+
+    <p>Of all the nebulæ, numbering some thousands, there is but a
+    single one which can be seen without a telescope. It is in the
+    constellation of Andromeda, and on a clear dark night can just
+    be seen with the unaided eye as a faint stain of light on the
+    sky. It has happened before now that persons noticing this
+    nebula for the first time have thought they had discovered a
+    comet. I would like you to try and find out this object for
+    yourselves.</p>
+
+    <p>If you look at it with an opera-glass it appears to be
+    distinctly elongated. You can see more of its structure when
+    you view it in larger instruments, but its nature was never
+    made clear until some beautiful photographs were taken by Mr.
+    Roberts (Fig. 9). Unfortunately, the nebula in Andromeda has
+    not been placed in the best position for its portrait from our
+    point of view. It seems as if it were a rather flat-shaped
+    object, turned nearly edgewise towards us. To look at the
+    pattern on a plate, you would naturally hold the plate so as to
+    be able to look at it squarely. The pattern would not be seen
+    well if the plate were so tilted that its edge was turned
+    towards you. That seems to be nearly the way <span class=
+    "pagenum"><a name="page339"
+       id="page339"></a>[pg 339]</span> in which we are forced to
+       view the nebula in Andromeda. We can trace in the photograph
+       some divisions extending entirely round the nebula, showing
+       that it seems to be formed of a series of rings; and there
+       are some outlying portions which form part of the same
+       system. Truly this is a marvellous object. It is impossible
+       for us to form any conception of the true dimensions of this
+       gigantic nebula; it is so far off that we have never yet
+       been able to determine its distance. Indeed, I may take this
+       opportunity of remarking that no astronomer has yet
+       succeeded in ascertaining the distance of any nebula.
+       Everything, however, points to the conclusion that they are
+       at least as far as the stars.</p>
+
+    <div class="figright"
+         style="width:300px;">
+        <a href="images/339.jpg"><img width="300"
+             src="images/339.jpg"
+             alt="FIG. 9. THE GREAT NEBULA IN ANDROMEDA." /></a><br />
+        FIG. 9. THE GREAT NEBULA IN ANDROMEDA.
+    </div>
+
+    <p>It is almost impossible to apply the methods which we use in
+    finding the distance of a star to the discovery of the distance
+    of the nebulæ. These flimsy bodies are usually too ill-defined
+    to admit of being measured with the precision and delicacy
+    required for the determination of distance. The measurements
+    necessary for this purpose can only be made from one star-like
+    point to another similar point. If we could choose a star in
+    <span class="pagenum"><a name="page340"
+       id="page340"></a>[pg 340]</span> the nebula and determine
+       its distance, then of course, we have the distance of the
+       nebula itself; but the difficulty is that we have, in
+       general, no means of knowing whether the star does actually
+       lie in the object. It may, for anything we can tell, lie
+       billions of miles nearer to us, or billions of miles further
+       off, and by merely happening to lie in the line of sight,
+       appear to glimmer in the nebula itself.</p>
+
+    <p>If we have any assurance that the star is surrounded by a
+    mass of this glowing vapor, then it may be possible to measure
+    that nebula's distance. It will occasionally happen that
+    grounds can be found for believing that a star which appears to
+    be in the glowing gas does veritably lie therein, and is not
+    merely seen in the same direction. There are hundreds of stars
+    visible in a good drawing or a good photograph of the famous
+    object in Andromeda, and doubtless large numbers of these are
+    merely stars which happen to lie in the same line of sight. The
+    peculiar circumstances attending the history of one star seem,
+    however, to warrant us in making the assumption that it was
+    certainly in the nebula. The history of this star is a
+    remarkable one. It suddenly kindled from invisibility into
+    brilliancy. How is a change so rapid in the lustre of a star to
+    be accounted for? In a few days its brightness had undergone an
+    extraordinary increase. Of course, this does not tell us for
+    certain that the star lay in the glowing gas; but the most
+    rational explanation that I have heard offered of this
+    occurrence is that due, I believe, to my friend Mr. Monck. He
+    has suggested that the sudden outbreak in brilliancy might be
+    accounted for on the same principles as those by which we
+    explain the <span class="pagenum"><a name="page341"
+       id="page341"></a>[pg 341]</span> ignition of meteors in our
+       atmosphere. If a dark star, moving along with terrific speed
+       through space, were suddenly to plunge into a dense region
+       of the nebula, heat and light must be evolved in sufficient
+       abundance to transform the star into a brilliant object. If,
+       therefore, we knew the distance of this star at the time it
+       was in Andromeda, we should, of course, learn the distance
+       of that interesting object. This has been attempted, and it
+       has thus been proved that the Great Nebula must be very much
+       further from us than is that star of whose distance I
+       attempted some time ago to give you a notion.</p>
+
+    <div class="figright"
+         style="width:350px;">
+        <a href="images/341.jpg"><img width="350"
+             src="images/341.jpg"
+             alt=
+           "FIG. 10. THE SOLAR SYSTEM AS COMPARED WITH A GREAT NEBULA." /></a><br />
+        FIG. 10. THE SOLAR SYSTEM AS COMPARED WITH A GREAT NEBULA.
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p>
+
+    <p>We thus realize the enormous size of the Great Nebula. It
+    appears that if, on a map of this object, we were to lay down,
+    accurately to scale, a map of the solar system, putting the sun
+    in the centre and all the planets around their true proportions
+    out to the boundary traced by Neptune, this area, vast though
+    it is, would be a mere speck on the drawing of the object. Our
+    system would have to be enormously bigger before it sufficed to
+    cover anything like the area of the sky included in one of
+    these great objects. Here is a sketch of a nebula, Fig. 10, and
+    near I have marked a dot, which is to indicate our solar
+    system. We may feel confident that the Great Nebula is at the
+    very least as mighty as this proportion would
+    indicate.</p><br clear="all" />
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="page342"
+       id="page342"></a>[pg 342]</span>
+
+    <h2>RAIN AND SNOW</h2>
+
+    <h4>(<span class="sc">From The Forms of Water.</span>)</h4>
+
+    <h3><span class="sc">By</span> JOHN TYNDALL.</h3>
+
+    <p>&nbsp;</p>
+    <hr class="short" />
+
+    <p><b>Oceanic Distillation.</b></p>
+
+    <div class="figleft"
+         style="width:200px;">
+        <a href="images/342.png"><img width="200"
+             src="images/342.png"
+             alt="SNOW CRYSTALS." /></a>SNOW CRYSTALS.
+    </div>
+
+    <p>At the equator, and within certain limits north and south of
+    it, the sun at certain periods of the year is directly overhead
+    at noon. These limits are called the Tropics of Cancer and of
+    Capricorn. Upon the belt comprised between these two circles
+    the sun's rays fall with their mightiest power; for here they
+    shoot directly downwards, and heat both earth and sea more than
+    when they strike slantingly.</p>
+
+    <p>When the vertical sunbeams strike the land they heat it, and
+    the air in contact with the hot soil becomes heated in turn.
+    But when heated the air expands, and when it expands it becomes
+    lighter. This lighter air rises, like wood plunged into water,
+    through the heavier air overhead.</p>
+
+    <p>When the sunbeams fall upon the sea the water is warmed,
+    though not so much as the land. The warmed water expands,
+    becomes thereby lighter, and therefore continues to float upon
+    the top. This upper layer of <span class="pagenum"><a name=
+    "page343"
+       id="page343"></a>[pg 343]</span> water warms to some extent
+       the air in contact with it, but it also sends up a quantity
+       of aqueous vapor, which being far lighter than air, helps
+       the latter to rise. Thus both from the land and from the sea
+       we have ascending currents established by the action of the
+       sun.</p>
+
+    <p>When they reach a certain elevation in the atmosphere, these
+    currents divide and flow, part towards the north and part
+    towards the south; while from the north and the south a flow of
+    heavier and colder air sets in to supply the place of the
+    ascending warm air.</p>
+
+    <p>Incessant circulation is thus established in the atmosphere.
+    The equatorial air and vapor flow above towards the north and
+    south poles, while the polar air flows below towards the
+    equator. The two currents of air thus established are called
+    the upper and the lower trade winds.</p>
+
+    <p>But before the air returns from the poles great changes have
+    occurred. For the air as it quitted the equatorial regions was
+    laden with aqueous vapor, which could not subsist in the cold
+    polar regions. It is there precipitated, falling sometimes as
+    rain, or more commonly as snow. The land near the pole is
+    covered with this snow, which gives birth to vast glaciers.</p>
+
+    <p>It is necessary that you should have a perfectly clear view
+    of this process, for great mistakes have been made regarding
+    the manner in which glaciers are related to the heat of the
+    sun.</p>
+
+    <p>It was supposed that if the sun's heat were diminished,
+    greater glaciers than those now existing would
+          <span class="pagenum"><a name="page344"
+       id="page344"></a>[pg 344]</span> be produced. But the
+       lessening of the sun's heat would infallibly diminish the
+       quantity of aqueous vapor, and thus cut off the glaciers at
+       their source. A brief illustration will complete your
+       knowledge here.</p>
+
+    <p>In the process of ordinary distillation, the liquid to be
+    distilled is heated and converted into vapor in one vessel, and
+    chilled and reconverted into liquid in another. What has just
+    been stated renders it plain that the earth and its atmosphere
+    constitute a vast distilling apparatus in which the equatorial
+    ocean plays the part of the boiler, and the chill regions of
+    the poles the part of the condenser. In this process of
+    distillation <i>heat</i> plays quite as necessary a part as
+    <i>cold</i>, and before Bishop Heber could speak of
+    "Greenland's icy mountains," the equatorial ocean had to be
+    warmed by the sun. We shall have more to say upon this question
+    afterwards.</p>
+
+    <p>The heating of the tropical air by the sun is
+    <i>indirect</i>. The solar beams have scarcely any power to
+    heat the air through which they pass; but they heat the land
+    and ocean, and these communicate their heat to the air in
+    contact with them. The air and vapor start upwards charged with
+    the heat thus communicated.</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>Tropical Rains.</b></p>
+
+    <p>But long before the air and vapor from the equator reach the
+    poles, precipitation occurs. Wherever a humid warm wind mixes
+    with a cold dry one, rain falls. Indeed the heaviest rains
+    occur at those places where the sun is vertically overhead. We
+    must enquire a little more closely into their
+    origin.</p><span class="pagenum"><a name="page345"
+       id="page345"></a>[pg 345]</span>
+
+    <p>Fill a bladder about two-thirds full of air at the sea
+    level, and take it to the summit of Mount Blanc. As you ascend,
+    the bladder becomes more and more distended; at the top of the
+    mountain it is fully distended, and has evidently to bear a
+    pressure from within. Returning to the sea level you find that
+    the tightness disappears, the bladder finally appearing as
+    flaccid as at first.</p>
+
+    <p>The reason is plain. At the sea level the air within the
+    bladder has to bear the pressure of the whole atmosphere, being
+    thereby squeezed into a comparatively small volume. In
+    ascending the mountain, you leave more and more of the
+    atmosphere behind; the pressure becomes less and less, and by
+    its expansive force the air within the bladder swells as the
+    outside pressure is diminished. At the top of the mountain the
+    expansion is quite sufficient to render the bladder tight, the
+    pressure within being then actually greater than the pressure
+    without. By means of an air-pump we can show the expansion of a
+    balloon partly filled with air, when the external pressure has
+    been in part removed.</p>
+
+    <p>But why do I dwell upon this? Simply to make plain to you
+    that the <i>unconfined air</i>, heated at the earth's surface,
+    and ascending by its lightness, must expand more and more the
+    higher it rises in the atmosphere.</p>
+
+    <p>And now I have to introduce to you a new fact, towards the
+    statement of which I have been working for some time. It is
+    this: <i>The ascending air is chilled by its expansion</i>.
+    Indeed this chilling is one source of the coldness of the
+    higher atmospheric regions. And <span class=
+       "pagenum"><a name="page346"
+       id="page346"></a>[pg 346]</span> now fix your eye upon those
+       mixed currents of air and aqueous vapor which rise from the
+       warm tropical ocean. They start with plenty of heat to
+       preserve the vapor as vapor; but as they rise they come into
+       regions already chilled, and they are still further chilled
+       by their own expansion. The consequence might be foreseen.
+       The load of vapor is in great part precipitated, dense
+       clouds are formed, their particles coalesce to rain-drops,
+       which descend daily in gushes so profuse that the word
+       "torrential" is used to express the copiousness of the
+       rainfall. I could show you this chilling by expansion, and
+       also the consequent precipitation of clouds.</p>
+
+    <p>Thus long before the air from the equator reaches the poles
+    its vapor is in great part removed from it, having redescended
+    to the earth as rain. Still a good quantity of the vapor is
+    carried forward, which yields hail, rain, and snow in northern
+    and southern lands.</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>Mountain Condensers.</b></p>
+
+    <p>To complete our view of the process of atmospheric
+    precipitation we must take into account the action of
+    mountains. Imagine a south-west wind blowing across the
+    Atlantic towards Ireland. In its passage it charges itself with
+    aqueous vapor. In the south of Ireland it encounters the
+    mountains of Kerry: the highest of these is Magillicuddy's
+    Reeks, near Killarney. Now the lowest stratum of this Atlantic
+    wind is that which is most fully charged with vapor. When it
+    encounters the base of the Kerry Mountains it is tilted up and
+    flows bodily over them. Its load of vapor is therefore carried
+    to a height, it expands on reaching the height,
+          <span class="pagenum"><a name="page347"
+       id="page347"></a>[pg 347]</span> it is chilled in
+       consequence of the expansion, and comes down in copious
+       showers of rain. From this, in fact, arises the luxuriant
+       vegetation of Killarney; to this, indeed, the lakes owe
+       their water supply. The cold crests of the mountains also
+       aid in the work of condensation.</p>
+
+    <p>Note the consequence. There is a town called Cahirciveen to
+    the south-west of Magillicuddy's Reeks, at which observations
+    of the rainfall have been made, and a good distance farther to
+    the north-east, right in the course of the south-west wind
+    there is another town, called Portarlington, at which
+    observations of rainfall have also been made. But before the
+    wind reaches the latter station it has passed over the
+    mountains of Kerry and left a great portion of its moisture
+    behind it. What is the result? At Cahirciveen, as shown by Dr.
+    Lloyd, the rainfall amounts to fifty-nine inches in a year,
+    while at Portarlington it is only twenty-one inches.</p>
+
+    <p>Again, you may sometimes descend from the Alps when the fall
+    of rain and snow is heavy and incessant, into Italy, and find
+    the sky over the plains of Lombardy blue and cloudless, the
+    wind at the same time <i>blowing over the plain towards the
+    Alps</i>. Below the wind is hot enough to keep its vapor in a
+    perfectly transparent state; but it meets the mountains, is
+    tilted up, expanded, and chilled. The cold of the higher
+    summits also helps the chill. The consequence is that the vapor
+    is precipitated as rain or snow, thus producing bad weather
+    upon the heights, while the plains below, flooded with the same
+    air, enjoy the aspect of the unclouded summer sun. Clouds
+    blowing <i>from</i> the <span class="pagenum"><a name="page348"
+       id="page348"></a>[pg 348]</span> Alps are also sometimes
+       dissolved over the plains of Lombardy.</p>
+
+    <p>In connection with the formation of clouds by mountains, one
+    particularly instructive effect may be here noticed. You
+    frequently see a streamer of cloud many hundred yards in length
+    drawn out from an Alpine peak. Its steadiness appears perfect,
+    though a strong wind may be blowing at the same time over the
+    mountain head. Why is the cloud not blown away? It <i>is</i>
+    blown away; its permanence is only apparent. At one end it is
+    incessantly dissolved; at the other end it is incessantly
+    renewed: supply and consumption being thus equalized, the cloud
+    appears as changeless as the mountain to which it seems to
+    cling. When the red sun of the evening shines upon these
+    cloud-streamers they resemble vast torches with their flames
+    blown through the air.</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>Architecture of Snow.</b></p>
+
+    <p>We now resemble persons who have climbed a difficult peak,
+    and thereby earned the enjoyment of a wide prospect. Having
+    made ourselves masters of the conditions necessary to the
+    production of mountain snow, we are able to take a
+    comprehensive and intelligent view of the phenomena of
+    glaciers.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/348.png"><img width="300"
+             src="images/348.png"
+             alt="SNOW CRYSTALS." /></a><br />
+        SNOW CRYSTALS.
+    </div>
+
+    <p>A few words are still necessary as to the formation of snow.
+    The molecules and atoms of all substances, when allowed free
+    play, build themselves into definite <span class=
+    "pagenum"><a name="page349"
+       id="page349"></a>[pg 349]</span> and, for the most part,
+       beautiful forms called crystals. Iron, copper, gold, silver,
+       lead, sulphur, when melted and permitted to cool gradually,
+       all show this crystallizing power. The metal bismuth shows
+       it in a particularly striking manner, and when properly
+       fused and solidified, self-built crystals of great size and
+       beauty are formed of this metal.</p>
+
+    <table summary="images of snow-stars">
+        <tr>
+            <td>
+                <div class="figleft"
+                     style="width:275px;">
+                    <a href="images/349-1.png"><img width="275"
+                         src="images/349-1.png"
+                         alt="SNOW-STAR." /></a><br />
+                    SNOW-STAR.
+                </div>
+            </td>
+
+            <td>
+                <div class="figright"
+                     style="width:275px;">
+                    <a href="images/349-2.png"><img width="275"
+                         src="images/349-2.png"
+                         alt="SNOW-STAR." /></a><br />
+                    SNOW-STAR.
+                </div>
+            </td>
+        </tr>
+    </table>
+
+    <p>If you dissolve salt-petre in water, and allow the solution
+    to evaporate slowly, you may obtain large crystals, for no
+    portion of the salt is converted into vapor. The water of our
+    atmosphere is fresh though it is derived from the salt sea.
+    Sugar dissolved in water, and permitted to evaporate, yields
+    crystals of sugar-candy. Alum readily crystallizes in the same
+    way. Flints dissolved, as they sometimes are in nature, and
+    permitted to crystallize, yield the prisms and pyramids of rock
+    crystal. Chalk dissolved and crystallized yields Iceland spar.
+    The diamond is <span class="pagenum"><a name="page350"
+       id="page350"></a>[pg 350]</span> crystallized carbon. All
+       our precious stones, the ruby, sapphire, beryl, topaz,
+       emerald, are all examples of this crystallizing power.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/350.png"><img width="300"
+             src="images/350.png"
+             alt="SNOW-STAR." /></a><br />
+        SNOW-STAR.
+    </div>
+
+    <p>You have heard of the force of gravitation, and you know
+    that it consists of an attraction of every particle of matter
+    for every other particle. You know that planets and moons are
+    held in their orbits by this attraction. But gravitation is a
+    very simple affair compared to the force, or rather forces, of
+    crystallization. For here the ultimate particles of matter,
+    inconceivably small as they are, show themselves possessed of
+    attractive and repellent poles, by the mutual action of which
+    the shape and structure of the crystal are determined. In the
+    solid condition the attracting poles are rigidly locked
+    together; but if sufficient heat be applied the bond of union
+    is dissolved, and in the state of fusion the poles are pushed
+    so far asunder as to be practically out of each other's range.
+    The natural tendency of the molecules to build themselves
+    together is thus neutralized.</p>
+
+    <p>This is the case with water, which as a liquid is to all
+    appearance formless. When sufficiently cooled the molecules are
+    brought within the play of the crystallizing force, and they
+    then arrange themselves in forms of indescribable beauty. When
+    snow is produced in <span class="pagenum"><a name="page351"
+       id="page351"></a>[pg 351]</span> calm air, the icy particles
+       build themselves into beautiful stellar shapes, each star
+       possessing six rays. There is no deviation from this type,
+       though in other respects the appearances of the snow-stars
+       are infinitely various. In the polar regions these exquisite
+       forms were observed by Dr. Scoresby, who gave numerous
+       drawings of them. I have observed them in mid-winter filling
+       the air, and loading the slopes of the Alps. But in England
+       they are also to be seen, and no words of mine could convey
+       so vivid an impression of their beauty as the annexed
+       drawings of a few of them, executed at Greenwich by Mr.
+       Glaisher.</p>
+
+    <div class="figright"
+         style="width:300px;">
+        <a href="images/351.png"><img width="300"
+             src="images/351.png"
+             alt="SNOW-STAR." /></a><br />
+        SNOW-STAR.
+    </div>
+
+    <p>It is worth pausing to think what wonderful work is going on
+    in the atmosphere during the formation and descent of every
+    snow-shower; what building power is brought into play! and how
+    imperfect seem the productions of human minds and hands when
+    compared with those formed by the blind forces of nature!</p>
+
+    <p>But who ventures to call the forces of nature blind? In
+    reality, when we speak thus we are describing our own
+    condition. The blindness is ours; and what we really ought to
+    say, and to confess, is that our powers are absolutely unable
+    to comprehend either the origin or the end of the operations of
+    nature.</p>
+
+    <p>But while we thus acknowledge our limits, there is
+    <span class="pagenum"><a name="page352"
+       id="page352"></a>[pg 352]</span> also reason for wonder at
+       the extent to which science has mastered the system of
+       nature. From age to age, and from generation to generation,
+       fact has been added to fact, and law to law, the true method
+       and order of the Universe being thereby more and more
+       revealed. In doing this science has encountered and
+       overthrown various forms of superstition and deceit, of
+       credulity and imposture. But the world continually produces
+       weak persons and wicked persons; and as long as they
+       continue to exist side by side, as they do in this our day,
+       very debasing beliefs will also continue to infest the
+       world.</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>Atomic Poles.</b></p>
+
+    <p>"What did I mean when, a few moments ago I spoke of
+    attracting and repellent poles?" Let me try to answer this
+    question. You know that astronomers and geographers speak of
+    the earth's poles, and you have also heard of magnetic poles,
+    the poles of a magnet being the points at which the attraction
+    and repulsion of the magnet are as it were concentrated.</p>
+
+    <p>Every magnet possesses two such poles; and if iron filings
+    be scattered over a magnet, each particle becomes also endowed
+    with two poles. Suppose such particles devoid of weight and
+    floating in our atmosphere, what must occur when they come near
+    each other? Manifestly the repellent poles will retreat from
+    each other, while the attractive poles will approach and
+    finally lock themselves together. And supposing the particles,
+    instead of a single pair, to possess several pairs of poles
+    arranged at definite points over their surfaces; you can then
+    picture them, in obedience to <span class="pagenum"><a name=
+    "page353"
+       id="page353"></a>[pg 353]</span> their mutual attractions
+       and repulsions, building themselves together to form masses
+       of definite shape and structure.</p>
+
+    <p>Imagine the molecules of water in calm cold air to be gifted
+    with poles of this description, which compel the particles to
+    lay themselves together in a definite order, and you have
+    before your mind's eye the unseen architecture which finally
+    produces the visible and beautiful crystals of the snow. Thus
+    our first notions and conceptions of poles are obtained from
+    the sight of our eyes in looking at the effects of magnetism;
+    and we then transfer these notions and conceptions to particles
+    which no eye has ever seen. The power by which we thus picture
+    to ourselves effects beyond the range of the senses is what
+    philosophers call the Imagination, and in the effort of the
+    mind to seize upon the unseen architecture of crystals, we have
+    an example of the "scientific use" of this faculty. Without
+    imagination we might have <i>critical</i> power, but not
+    <i>creative</i> power in science.</p>
+
+    <p>&nbsp;</p>
+
+    <p><b>Architecture of Lake Ice.</b></p>
+
+    <p>We have thus made ourselves acquainted with the beautiful
+    snow-flowers self-constructed by the molecules of water in
+    calm, cold air. Do the molecules show this architectural power
+    when ordinary water is frozen? What, for example, is the
+    structure of the ice over which we skate in winter? Quite as
+    wonderful as the flowers of the snow. The observation is rare,
+    if not new, but I have seen in water slowly freezing six-rayed
+    ice-stars formed, and floating free on the surface. A six-rayed
+    star, moreover, is typical of the construction
+          <span class="pagenum"><a name="page354"
+       id="page354"></a>[pg 354]</span> of all our lake ice. It is
+       built up of such forms wonderfully interlaced.</p>
+
+    <p>Take a slab of lake ice and place it in the path of a
+    concentrated sunbeam. Watch the track of the beam through the
+    ice. Part of the beam is stopped, part of it goes through; the
+    former produces internal liquefaction, the latter has no effect
+    whatever upon the ice. But the liquefaction is not uniformly
+    diffused. From separate spots of the ice little shining points
+    are seen to sparkle forth. Every one of those points is
+    surrounded by a beautiful liquid flower with six petals.</p>
+
+    <p>Ice and water are so optically alike that unless the light
+    fall properly upon these flowers you cannot see them. But what
+    is the central spot? A vacuum. Ice swims on water because, bulk
+    for bulk, it is lighter than water; so that when ice is melted
+    it shrinks in size. Can the liquid flowers then occupy the
+    whole space of the ice melted? Plainly no. A little empty space
+    is formed with the flowers, and this space, or rather its
+    surface, shines in the sun with the lustre of burnished
+    silver.</p>
+
+    <p>In all cases the flowers are formed parallel to the surface
+    of freezing. They are formed when the sun shines upon the ice
+    of every lake; sometimes in myriads, and so small as to require
+    a magnifying glass to see them. They are always attainable, but
+    their beauty is often marred by internal defects of the ice.
+    Every one portion of the same piece of ice may show them
+    exquisitely, while a second portion shows them imperfectly.</p>
+
+    <p>Annexed is a very imperfect sketch of these beautiful
+    figures.</p><span class="pagenum"><a name="page355"
+       id="page355"></a>[pg 355]</span>
+
+    <p>Here we have a reversal of the process of crystallization.
+    The searching solar beam is delicate enough to take the
+    molecules down without deranging the order of their
+    architecture. Try the experiment for yourself with a
+    pocket-lens on a sunny day. You will not find the flowers
+    confused; they all lie parallel to the surface of freezing. In
+    this exquisite way every bit of the ice over which our skaters
+    glide in winter is put together.</p>
+
+    <p>I said that a portion of the sunbeam was stopped by the ice
+    and liquefied it. What is this portion? The dark heat of the
+    sun. The great body of the light waves and even a portion of
+    the dark ones, pass through the ice without losing any of their
+    heating power. When properly concentrated on combustible
+    bodies, even after having passed through the ice, their burning
+    power becomes manifest.</p>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/355.png"><img width="400"
+             src="images/355.png"
+             alt="LIQUID FLOWERS IN LAKE ICE." /></a><br />
+        LIQUID FLOWERS IN LAKE ICE.
+    </div>
+
+    <p>And the ice itself may be employed to concentrate them. With
+    an ice-lens in the polar regions Dr. Scoresby has often
+    concentrated the sun's rays so as to make them burn wood, fire
+    gunpowder, and melt lead; thus proving that the heating power
+    is retained <span class="pagenum"><a name="page356"
+       id="page356"></a>[pg 356]</span> by the rays, even after
+       they have passed through so cold a substance.</p>
+
+    <p>By rendering the rays of the electric lamp parallel, and
+    then sending them through a lens of ice, we obtain all the
+    effects which Dr. Scoresby obtained with the rays of the
+    sun.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/356.png"><img width="500"
+             src="images/356.png"
+             alt="snowflakes" /></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="page357"
+       id="page357"></a>[pg 357]</span>
+
+    <h2>THE ORGANIC WORLD</h2>
+
+    <h4>(<span class="sc">From The Elements of
+    Science.</span>)</h4>
+
+    <h3><span class="sc">By</span> ST. GEORGE MIVART F.R.S.</h3>
+    <hr class="short" />
+
+    <div class="figleft"
+         style="width:100px;">
+        <a href="images/357.png"><img width="100"
+             src="images/357.png"
+             alt="T" /></a>
+    </div>
+
+    <p>The number of all the various kinds of living creatures is
+    so enormous that it would be impossible to study them
+    profitably, were they not classified in an orderly manner.
+    Therefore the whole mass has been divided, in the first place,
+    into two supreme groups, fancifully termed kingdoms&mdash;the
+    "animal kingdom" and the "vegetal kingdom." Each of these is
+    subdivided into an orderly series of subordinate groups,
+    successively contained one a within the other, and named
+    sub-kingdoms, classes, orders, families, genera and species.
+    The lowest group but one is the "genus," which contains one or
+    more different kinds termed "species," as e.g., the species
+    "wood anemone" and the species "blue titmouse." The lowest
+    group of all&mdash;a species&mdash;may be said to consist of
+    individuals which differ from each other only by trifling
+    characters, such as characters due to difference of sex, while
+    their peculiar organization is faithfully reproduced by
+    generation as a whole, though small individual differences
+    exist in all cases.</p>
+
+    <p>The vegetal, or vegetable, kingdom, consists of the great
+    mass of flowering plants, many of which, however, have such
+    inconspicuous flowers that they are <span class=
+    "pagenum"><a name="page358"
+       id="page358"></a>[pg 358]</span> mistakenly regarded as
+       flowerless, as is often the case with the grasses, the
+       pines, and the yews. Another mass, or sub-kingdom, of plants
+       consists of the really flowerless plants, such as the ferns,
+       horsetails (Fig. 1), lycopods, and mosses. Sea and
+       fresh-water weeds (<i>algæ</i>), and mushrooms, or "moulds,"
+       of all kinds (<i>fungi</i>), amongst which are the now
+       famous "bacteria," constitute a third and lowest set of
+       plants.</p>
+
+    <div class="figleft"
+         style="width:400px;">
+        <a href="images/358.png"><img width="400"
+             src="images/358.png"
+             alt=
+           "FIG. 1. HORSE-TAIL (Equisetum drummondii)." /></a><br />
+        FIG. 1. HORSE-TAIL (<i>Equisetum drummondii</i>).
+    </div>
+
+    <p>The animal kingdom consists, first, of a sub-kingdom of
+    animals which possess a spinal column, or backbone, and which
+    are known as vertebrate animals. Such are all beasts, birds,
+    reptiles, and fishes. There are also a variety of remotely
+    allied marine organisms known as tunicates, sea-squirts, or
+    ascidians (Fig. 2). There is, further, an immense group of
+    arthropods, consisting of all insects, crab-like creatures,
+    hundred-legs and their allies, with spiders, scorpions, tics
+    and mites. We have also the sub-kingdom of shell-fish or
+    molluscs, <span class="pagenum"><a name="page359"
+       id="page359"></a>[pg 359]</span> including cuttle-fishes,
+       snails, whelks, limpets, the oyster, and a multitude of
+       allied forms. A multitudinous sub-kingdom of worms also
+       exists, as well as another of star-fishes and their
+       congeners. There is yet another of zoophytes, or polyps, and
+       another of sponges, and, finally, we have a sub-kingdom of
+       minute creatures, or animalculæ, of very varied forms, which
+       may make up the sub-kingdom of <i>Protozoa</i>, consisting
+       of animals which are mostly unicellular.</p>
+
+    <div class="figright"
+         style="width:175px;">
+        <a href="images/359.png"><img width="175"
+             src="images/359.png"
+             alt="FIG. 2. A TUNICATE (Ascidia)." /></a><br />
+        FIG. 2. A TUNICATE (<i>Ascidia</i>).
+    </div>
+
+    <p>Multitudinous and varied as are the creatures which compose
+    this immense organic world, they nevertheless exhibit a very
+    remarkable uniformity of composition in their essential
+    structure. Every living creature from a man to a mushroom, or
+    even to the smallest animalcule or unicellular plant is always
+    partly fluid, but never entirely so. Every living creature also
+    consists in part (and that part is the most active living part)
+    of a soft, viscid, transparent, colorless substance, termed
+    protoplasm, which can be resolved into the four elements,
+    oxygen, hydrogen, nitrogen and carbon. Besides these four
+    elements, living organisms commonly contain sulphur,
+    phosphorus, chlorine, potassium, sodium, calcium, magnesium and
+    iron.</p>
+
+    <p>In the fact that living creatures always consist of the four
+    elements, oxygen, hydrogen, nitrogen and carbon, we have a
+    fundamental character whereby the organic and inorganic (or
+    non-living) worlds are to be <span class="pagenum"><a name=
+    "page360"
+       id="page360"></a>[pg 360]</span> distinguished, for as we
+       have seen, inorganic bodies, instead of being thus uniformly
+       constituted, may consist of the most diverse elements and
+       sometimes of but two or even of only one.</p>
+
+    <p>Again, many minerals, such as crystals, are bounded by plain
+    surfaces, and, with very few exceptions (spathic and hematite
+    iron and dolomite are such exceptions) none are bounded by
+    curved lines and surfaces, while living organisms are bounded
+    by such lines and surfaces.</p>
+
+    <p>Yet, again, if a crystal be cut through, its internal
+    structure will be seen to be similar throughout. But if the
+    body of any living creature be divided, it will, at the very
+    least, be seen to consist of a variety of minute distinct
+    particles, called "granules," variously distributed throughout
+    its interior.</p>
+
+    <p>All organisms consist either&mdash;as do the simplest,
+    mostly microscopic, plants and animals&mdash;of a single minute
+    mass of protoplasm, or of a few, or of many, or of an enormous
+    aggregation of such before-mentioned particles, each of which
+    is one of those bodies named a "cell" (Fig. 3). Cells may, or
+    may not, be enclosed in an investing coat or "cell-wall." Every
+    cell generally contains within it a denser, normally
+    spheroidal, body known as the nucleus.</p>
+
+    <p>Now protoplasm is a very unstable substance&mdash;as we have
+    seen many substances are whereof nitrogen is a component
+    part&mdash;and it possesses active properties which are not
+    present in the non-living, or inorganic world. In the latter,
+    differences of temperature will produce motion in the shape of
+    "currents," as we have seen with respect to masses of air and
+    water. But in a portion <span class="pagenum"><a name="page361"
+       id="page361"></a>[pg 361]</span> of protoplasm, an internal
+       circulation of currents in definite lines will establish
+       itself from other causes.</p>
+
+    <p>Inorganic bodies, as we have seen, will expand with heat, as
+    they may also do from imbibing moisture; but living protoplasm
+    has an apparently spontaneous power of contraction and
+    expansion under certain external conditions which do not
+    occasion such movements in inorganic matter.</p>
+
+    <div class="figright"
+         style="width:300px;">
+        <a href="images/361.png"><img width="300"
+             src="images/361.png"
+             alt="FIG. 3. CELL FROM A SALAMANDER." /></a><br />
+        FIG. 3. CELL FROM A SALAMANDER.
+
+        <p><i>n</i>, nucleus; <i>n'</i>, nucleolus embedded in the
+        network of chromatin threads; <i>k</i>, network of the cell
+        external to the nucleus; <i>a</i>, attraction-sphere or
+        archoplasm containing minute bodies called centrosomes;
+        <i>cl</i>, membrane enclosing the cell externally,
+        <i>nl</i>, membrane surrounding the nucleus; <i>c</i>,
+        centrosomes.</p>
+    </div>
+
+    <p>Under favoring conditions, protoplasm has a power of
+    performing chemical changes, which result in producing heat far
+    more gently and continuously than it is produced by the
+    combustion of inorganic bodies. Thus it is that the heat is
+    produced which makes its presence evident to us in what we call
+    "warm-blooded animals," the most warm-blooded of all being
+    birds.</p>
+
+    <p>Protoplasm has also the wonderful power of transforming
+    certain adjacent substances into material like
+    itself&mdash;into its own substance&mdash;and so, in a sense,
+    creating a new material. Thus it is that organisms have the
+    power to nourish themselves and grow. An animal would vainly
+    swallow the most nourishing food if the ultimate, protoplasmic
+    particles of its body had not this power of "transforming"
+    suitable <span class="pagenum"><a name="page362"
+       id="page362"></a>[pg 362]</span> substances brought near
+       them in ways to be hereinafter noticed.</p>
+
+    <p>Without that, no organism could ever "grow." The growth of
+    organisms is utterly different from the increase in size of
+    inorganic bodies. Crystals, as we have seen, grow merely by
+    external increment; but organisms grow by an increment which
+    takes place in the very innermost substance of the tissues
+    which compose their bodies, and the innermost substance of the
+    cells which compose such tissues; this peculiar form of growth
+    is termed <i>intussusception</i>.</p>
+
+    <p>Protoplasm, after thus augmenting its mass, has a further
+    power of spontaneous division, whereby the mass of the entire
+    organism whereof such protoplasm forms a part, is augmented and
+    so growth is brought about.</p>
+
+    <p>The small particles of protoplasm which constitute "cells"
+    are far indeed from being structureless. Besides the nucleus
+    already mentioned there is a delicate network of threads of a
+    substance called <i>chromatin</i> within it, and another
+    network permeating the fluid of the cell substance, which
+    invest the nucleus often with further complications. These
+    networks generally perform (or undergo) a most complex series
+    of changes every time a cell spontaneously divides. In certain
+    cases, however, it appears that the nucleus divides into two in
+    a more simple fashion, the rest of the cell contents
+    subsequently dividing&mdash;each half enclosing one part of the
+    previously divided nucleus. It is by a continued process of
+    cell division that the complex structures of the most complex
+    organisms is brought about.</p>
+
+    <p>The division of a cell, or particle of protoplasm, is
+    <span class="pagenum"><a name="page363"
+       id="page363"></a>[pg 363]</span> indeed a necessary
+       consequence of its complete nutrition.</p>
+
+    <p>For new material can only be absorbed by its surface. But as
+    the cell grows, the proportion borne by its surface to its
+    mass, continually decreases; therefore this surface must soon
+    be too small to take in nourishment enough, and the particle,
+    or cell, must therefore either die or divide. By dividing, its
+    parts can continue the nutritive process till their surface, in
+    turn, becomes insufficient, when they must divide again, and so
+    on. Thus the term "feeding" has two senses. "To feed a horse,"
+    ordinarily means to give it a certain quantity of hay, oats or
+    what not; and such indeed is one kind of feeding. But
+    obviously, if the nourishment so taken could not get from the
+    stomach and intestines into the ultimate particles and cells of
+    the horse's body, the horse could not be nourished, and still
+    less could it grow. It is this latter process, called
+    assimilation, which is the real and essential process of
+    feeding, to which the process ordinarily so called is but
+    introductory.</p>
+
+    <p>Protoplasm has also the power of forming and ejecting from
+    its own substance, other substances which it has made, but
+    which are of a different nature to its own. This function, as
+    before said, is termed secretion; and we know the liver
+    secretes bile, and that the cow's udder secretes milk.</p>
+
+    <p>Here again we have an external and an internal process. The
+    milk is drawn forth from a receptacle, the udder, into which it
+    finds its way, and so, in a superficial sense, it may be called
+    an organ of secretion. Nevertheless the true internal secretion
+    takes place in <span class="pagenum"><a name="page364"
+       id="page364"></a>[pg 364]</span> the innermost substance of
+       the cells or particles of protoplasm, of the milk-land,
+       which particles really form that liquid.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/364.png"><img width="300"
+             src="images/364.png"
+             alt=
+           "FIG. 4. AMOEBA SHOWN IN TWO OF THE MANY IRREGULAR SHAPES IT ASSUMES." /></a>
+
+        <p>FIG. 4. AMOEBA SHOWN IN TWO OF THE MANY IRREGULAR SHAPES
+        IT ASSUMES. <i>(After Howes</i>.)</p>
+
+        <p>The clear space within it is a contractile vesicle. The
+        dark body is the nucleus. In the right-hand figure there is
+        shown a particle of food, passing through the external
+        surface.</p>
+    </div>
+
+    <p>But every living creature consists at first entirely of a
+    particle of protoplasm. Therefore every other kind of substance
+    which may be found in every kind of plant or animal, must have
+    been formed through it, and be, in fact, a secretion from
+    protoplasm. Such is the rosy cheek of an apple, or of a maiden,
+    the luscious juice of the peach, the produce of the castor-oil
+    plant, the baleen that lines the whale's enormous jaws, as well
+    as that softest product, the fur of the chinchilla. Indeed,
+    every particle of protoplasm requires, in order that it may
+    live, a continuous process of exchange. It needs to be
+    continuously first built up by food, and then broken down by
+    discharging what is no longer needful for its healthy
+    existence. Thus the life of every organism is a life of almost
+    incessant change, not only in its being as a whole, but in that
+    of all its protoplasmic particles also.</p>
+
+    <p>Prominent among such processes is that of an interchange of
+    gases between the living being and its environment. This
+    process consists in an absorption of oxygen and a giving-out of
+    carbonic acid, which exchange is termed
+    respiration.</p><span class="pagenum"><a name="page365"
+       id="page365"></a>[pg 365]</span>
+
+    <p>Lastly, protoplasm has a power of motion when appropriately
+    acted on. It will then contract or expand its shape by
+    alternate protrusions and retractions of parts of its
+    substance. These movements are termed amoebiform, because they
+    quite resemble the movements of a small animalcule which is
+    named amoeba. (See Fig. 4.)</p>
+
+    <p>Such is the ultimate structure, and such are the fundamental
+    activities or functions of living organisms, as far as they can
+    here be described, from the lowest animalcule and unicellular
+    plant, up to the most complex organisms and the body of man
+    himself.</p>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/365.png"><img width="400"
+             src="images/365.png"
+             alt="cliffs" /></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="page366"
+       id="page366"></a>[pg 366]</span>
+
+    <h2>INHABITANTS OF MY POOL</h2>
+
+    <h4>(<span class="sc">From Magic Glasses.</span>)</h4>
+
+    <h3><span class="sc">By</span> ARABELLA B. BUCKLEY.</h3>
+    <hr class="short" />
+
+    <div class="figleft"
+         style="width:100px;">
+        <a href="images/366.png"><img width="100"
+             src="images/366.png"
+             alt="cliffs" /></a>
+    </div>
+
+    <p>The pool lies in a deep hollow among a group of rocks and
+    boulders, close to the entrance of the cove, which can only be
+    entered at low water; it does not measure more than two feet
+    across, so that you can step over it, if you take care not to
+    slip on the masses of green and brown seaweed growing over the
+    rocks on its sides, as I have done many a time when collecting
+    specimens for our salt-water aquarium. I find now the only way
+    is to lie flat down on the rock, so that my hands and eyes are
+    free to observe and handle, and then, bringing my eye down to
+    the edge of the pool, to lift the seaweeds and let the sunlight
+    enter into the chinks and crannies. In this way I can catch
+    sight of many a small being either on the seaweed or the rocky
+    ledges, and even creatures transparent as glass become visible
+    by the thin outline gleaming in the sunlight. Then I pluck a
+    piece of seaweed, or chip off a fragment of rock with a
+    sharp-edged collecting knife, bringing away the specimen
+    uninjured upon it, and place it carefully in its own separate
+    bottle to be carried home alive and well.</p>
+
+    <p>Now though this little pool and I are old friends, I
+    <span class="pagenum"><a name="page367"
+       id="page367"></a>[pg 367]</span> find new treasures in it
+       almost every time I go, for it is almost as full of living
+       things as the heavens are of stars, and the tide as it comes
+       and goes brings many a mother there to find a safe home for
+       her little ones, and many a waif and stray to seek shelter
+       from the troublous life of the open ocean.</p>
+
+    <p>You will perhaps find it difficult to believe that in this
+    rock-bound basin there can be millions of living creatures
+    hidden away among the fine feathery weeds; yet so it is. Not
+    that they are always the same. At one time it may be the home
+    of myriads of infant crabs, not an eighth of an inch long,
+    another of baby sea-urchins only visible to the naked eye as
+    minute spots in the water, at another of young jelly-fish
+    growing on their tiny stalks, and splitting off one by one as
+    transparent bells to float away with the rising tide. Or it may
+    be that the whelk has chosen this quiet nook to deposit her
+    leathery eggs; or young barnacles, periwinkles, and limpets are
+    growing up among the green and brown tangles, while the
+    far-sailing velella and the stay-at-home sea-squirts, together
+    with a variety of other sea-animals, find a nursery and shelter
+    in their youth in this quiet harbor of rest.</p>
+
+    <p>And besides these casual visitors there are numberless
+    creatures which have lived and multiplied there, ever since I
+    first visited the pool. Tender red, olive-colored, and green
+    seaweeds, stony corallines, and acorn-barnacles lining the
+    floor, sea-anemones clinging to the sides, sponges tiny and
+    many-colored hiding under the ledges, and limpets and mussels
+    wedged in the cracks. These can be easily seen with the naked
+    eye, but they are not the most numerous inhabitants; for these
+    <span class="pagenum"><a name="page368"
+       id="page368"></a>[pg 368]</span> we must search with a
+       magnifying glass, which will reveal to us wonderful
+       fairy-forms, delicate crystal vases with tiny creatures in
+       them whose transparent lashes make whirlpools in the water,
+       living crystal bells so tiny that whole branches of them
+       look only like a fringe of hair, jelly globes rising and
+       falling in the water, patches of living jelly clinging to
+       the rocky sides of the pool, and a hundred other forms, some
+       so minute that you must examine the fine sand in which they
+       lie under a powerful microscope before you can even guess
+       that they are there.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/368.png"><img width="500"
+             src="images/368.png"
+             alt="FIG. 1. GROUP OF SEAWEEDS." /></a><br />
+        FIG. 1. GROUP OF SEAWEEDS.<br />
+        (Natural size.)<br />
+        1, <i>Ulva Linza.</i> 2, <i>Sphacelaria filicina.</i> 3,
+        <i>Polysiphonia urceolata.</i> 4, <i>Corallina
+        officinalis.</i>
+    </div>
+
+    <p>So it has proved a rich hunting-ground, where summer and
+    winter, spring and autumn, I find some form to put under my
+    magic glass. There I can watch it for weeks growing and
+    multiplying under my care; moved only from the aquarium, where
+    I keep it supplied with healthy sea-water, to the tiny
+    <span class="pagenum"><a name="page369"
+       id="page369"></a>[pg 369]</span> transparent trough in which
+       I place it for a few hours to see the changes it has
+       undergone. I could tell you endless tales of transformations
+       in these tiny lives, but I want to-day to show you a few of
+       my friends, most of which I brought yesterday fresh from the
+       pool, and have prepared for you to examine.</p>
+
+    <div class="figright"
+         style="width:300px;">
+        <a href="images/369.png"><img width="300"
+             src="images/369.png"
+             alt="FIG. 2. Ulva lactuca, A GREEN-SEAWEED," /></a>
+
+        <p>FIG. 2. <i>Ulva lactuca</i>, A GREEN-SEAWEED, GREATLY
+        MAGNIFIED TO SHOW STRUCTURE. (<i>After Orested).</i></p>
+
+        <p>s, Spores in the cells, <i>ss</i>, Spores swimming out.
+        <i>h</i>, Holes through which spores have escaped.</p>
+    </div>
+
+    <p>Let us begin with seaweeds. I have said that there are three
+    leading colors in my pool&mdash;green, olive, and red&mdash;and
+    these tints mark roughly three kinds of weed, though they occur
+    in an endless variety of shapes. Here is a piece of the
+    beautiful pale green seaweed, called the Laver or Sea-Lettuce,
+    <i>Ulva Linza</i> (1, Fig. 1),<a id="footnotetag4"
+       name="footnotetag4"></a><a href=
+       "#footnote4"><sup>4</sup></a> which grows in long ribbons in
+       a sunny nook in the water. I have placed under the first
+       microscope a piece of this weed which is just sending out
+       young seaweeds in the shape of tiny cells, with lashes very
+       like those we saw coming from the moss-flower, and I have
+       pressed them in the position in which they would naturally
+       leave the plant. You will also see on this side several
+       cells in which these tiny spores are forming, ready to burst
+       out and swim; for this green weed is merely a collection of
+       cells, like the single-celled plants on land. Each cell
+       <span class="pagenum"><a name="page370"
+       id="page370"></a>[pg 370]</span> can work as a separate
+       plant; it feeds, grows, and can send out its own young
+       spores.</p>
+
+    <p>This deep olive-green feathery weed (2, Fig. 1), of which a
+    piece is magnified under the next microscope (2, Fig. 3), is
+    very different. It is a higher plant, and works harder for its
+    living, using the darker rays of sunlight which penetrate into
+    shady parts of the pool. So it comes to pass that its cells
+    divide the work. Those of the feathery threads make the food,
+    while others, growing on short stalks on the shafts of the
+    feather, make and send out the young spores.</p>
+
+    <p>Lastly, the lovely red threadlike weeds, such as this
+    <i>Polysiphonia urceolata</i> (3, Fig. 1), carry actual urns on
+    their stems like those of mosses. In fact, the history of these
+    urns (see 3, Fig. 3), is much the same in the two classes of
+    plants, only that instead of the urn being pushed up on a thin
+    stalk as in the moss, it remains on the seaweed close down to
+    the stem, when it grows out of the plant-egg, and the tiny
+    plant is shut in till the spores are ready to swim out.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/370.png"><img width="300"
+             src="images/370.png"
+             alt=
+           "FIG. 3. THREE SEAWEEDS OF FIG. 1 MUCH MAGNIFIED TO SHOW FRUITS." /></a>
+
+        <p>FIG. 3. THREE SEAWEEDS OF FIG. 1 MUCH MAGNIFIED TO SHOW
+        FRUITS. (<i>Harvey.</i>)</p>
+
+        <p>2, <i>Sphacelaria filicina.</i> 3, <i>Polysiphonia
+        urceolata.</i> 4, <i>Corallina officinalis.</i></p>
+    </div>
+
+    <p>The stony corallines (4, Figs. 1 and 3), which build so much
+    carbonate of lime into their stems, are near relations of the
+    red seaweeds. There are plenty of them in my pool. Some of
+    them, of a deep purple color, grow upright in stiff groups
+    about three or four <span class="pagenum"><a name="page371"
+       id="page371"></a>[pg 371]</span> inches high; and others,
+       which form crusts over the stones and weeds, are a pale rose
+       color; but both kinds, when the plant dies, leaving the
+       stony skeleton (1, Fig. 4), are a pure white, and used to be
+       mistaken for corals. They belong to the same order of plants
+       as the red weeds, which all live in shady nooks in the
+       pools, and are the highest of their race.</p>
+
+    <div class="figright"
+         style="width:400px;">
+        <a href="images/371.png"><img width="400"
+             src="images/371.png"
+             alt=
+           "FIG. 4. CORALLINE AND SERTULARIA, TO SHOW LIKENESS BETWEEN THE ANIMAL SERTULARIA AND THE PLANT CORALLINE." /></a>
+
+        <p>FIG. 4. CORALLINE AND SERTULARIA, TO SHOW LIKENESS
+        BETWEEN THE ANIMAL SERTULARIA AND THE PLANT
+        CORALLINE.</p>1, <i>Corallina officinalis.</i> 2,
+        <i>Sertularia filicula.</i>
+    </div>
+
+    <p>My pool is full of different forms of these four weeds. The
+    green ribbons float on the surface rooted to the sides of the
+    pool, and, as the sun shines upon it, the glittering bubbles
+    rising from them show that they are working up food out of the
+    air in the water, and giving off oxygen. The brown weeds lie
+    chiefly under the shelves of rocks, for they can manage with
+    less sunlight, and use the darker rays which pass by the green
+    weeds; and last of all, the red weeds and corallines, small and
+    delicate in form, line the bottom of the pool in its darkest
+    nooks.</p>
+
+    <p>And now if I hand round two specimens,&mdash;one a
+    coralline, and the other something you do not yet know,&mdash;I
+    am sure you will say at first sight that they belong to the
+    same family, and, in fact, if you buy at the seaside a group of
+    seaweeds gummed on paper, you will most likely get both these
+    among them. Yet the truth is; that while the coralline (1, Fig.
+    4) is a plant, <span class="pagenum"><a name="page372"
+       id="page372"></a>[pg 372]</span> the other specimen (2),
+       which is called <i>Sertularia filicula</i>, is an
+       animal.</p>
+
+    <p>This special sertularian grows up right in my pool on stones
+    or often on seaweeds, but I have here (Fig. 5) another and much
+    smaller one which lives literally in millions hanging its cups
+    downwards. I find it not only under the narrow ledges of the
+    pool sheltered by the seaweed, but forming a fringe along all
+    the rocks on each side of the cove near to low-water mark, and
+    for a long time I passed it by thinking it was of no interest.
+    But I have long since given up thinking this of anything,
+    especially in my pool, for my magic glass has taught me that
+    there is not even a living speck which does not open out into
+    something marvellous and beautiful. So I chipped off a small
+    piece of rock and brought the fringe home, and found, when I
+    hung it up in clear sea-water as I have done over this glass
+    trough (Fig. 5) and looked at it through the lens, that each
+    thread of the dense fringe, in itself not a quarter of an inch
+    deep, turns out to be a tiny sertularian with at least twenty
+    mouths. You can see this with your pocket lens even as it hangs
+    here, and when you have examined it you can by and by take off
+    one thread and put it carefully in the trough. I promise you a
+    sight of the most beautiful little beings which exist in
+    nature.</p>
+
+    <div class="figleft"
+         style="width:350px;">
+        <a href="images/372.png"><img width="350"
+             src="images/372.png"
+             alt=
+           "FIG. 5. Sertularia tenella, HANGING FROM A SPLINT OF ROCK OVER A WATER TROUGH." /></a>
+
+        <p>FIG. 5. <i>Sertularia tenella</i>, HANGING FROM A SPLINT
+        OF ROCK OVER A WATER TROUGH. ALSO PIECE ENLARGED TO SHOW
+        THE ANIMAL ROTRUDING.</p>
+    </div>
+
+    <p>Come and look at it. It is a horny-branched stem
+          <span class="pagenum"><a name="page373"
+       id="page373"></a>[pg 373]</span> with a double row of tiny
+       cups all along each side. Out of these cups there appear a
+       row of tiny cups all along each side (see Fig. 5), Out of
+       these cups there appear from time to time sixteen minute
+       transparent tentacles as fine as spun glass, which wave
+       about in the water. If you shake the glass a little, in an
+       instant each crystal star vanishes into its cup, to come out
+       again a few minutes later; so that now here, now there, the
+       delicate animal-flowers spread out on each side of the stem,
+       and the tree is covered with moving beings. These tentacles
+       are feelers, which lash food into a mouth and stomach in
+       each cup, where it is digested and passed, through a hole in
+       the bottom, along a jelly thread which runs down the stem
+       and joins all the mouths together. In this way the food is
+       distributed all over the tree, which is, in fact, one animal
+       with many feeding-cups. Some day I will show you one of
+       these cups with the tentacles stretched out and mounted on a
+       slide, so that you can examine a tentacle with a very strong
+       magnifying power. You will then see that it is dotted over
+       with cells, in which are coiled fine threads. The animal
+       uses these threads to paralyze the creatures on which it
+       feeds, for at the base of each thread there is a poison
+       gland.</p>
+
+    <p>In the larger Sertularia the whole branched tree is
+    connected by jelly threads, running through the stem, and all
+    the thousands of mouths are spread out in the water. One large
+    form called <i>Sertularia cupressina</i> grows sometimes three
+    feet high and bears as many as a hundred thousand cups, with
+    living mouths, on its branches.</p>
+
+    <p>The next of my minute friends I can only show to
+          <span class="pagenum"><a name="page374"
+       id="page374"></a>[pg 374]</span> the class in a diagram, but
+       you will see it under the fourth microscope by and by. I had
+       great trouble in finding it yesterday, though I know its
+       haunts upon the green weed, for it is so minute and
+       transparent that even when the weed is in a trough a
+       magnifying-glass will scarcely detect it. And I must warn
+       you that if you want to know any of the minute creatures we
+       are studying, you must visit one place constantly. You may
+       in a casual way find many of them on seaweed, or in the damp
+       ooze and mud, but it will be by chance only; to look for
+       them with any certainty you must take trouble in making
+       their acquaintance.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/374.png"><img width="300"
+             src="images/374.png"
+             alt=
+           "FIG. 6. Thuricolla folliculata and Chilomonas amygdalum." /></a>
+
+        <p>FIG. 6. <i>Thuricolla folliculata</i> and <i>Chilomonas
+        amygdalum</i>. (<i>Saville Kent</i>.)</p>
+
+        <p>1, <i>Thuricolla</i> erect. 2, Retracted. 3, Dividing.
+        4, <i>Chilomonas amygdalum. hc,</i> Horny carapace,
+        <i>cv</i>, Contractile vesicle. <i>v</i> Closing
+        valves.</p>
+    </div>
+
+    <p>Turning then to the diagram (Fig. 6) I will describe it as I
+    hope you will see it under the microscope&mdash;a curious,
+    tiny, perfectly transparent open-mouthed vase standing upright
+    on the weed, and having an equally transparent being rising up
+    in it and waving its tiny lashes in the water. This is really
+    all one animal, the vase <i>hc</i> being the horny covering or
+    carapace of the body, which last stands up like a tube in the
+    centre. If you watch carefully, you may even see the minute
+    atoms of food twisting round inside the tube until they are
+    digested, after they have been swept in at the wide open mouth
+    by the whirling lashes. You will see this <span class=
+    "pagenum"><a name="page375"
+       id="page375"></a>[pg 375]</span> more clearly if you put a
+       little rice-flour, very minutely powdered and colored by
+       carmine, into the water; for you can trace these red atoms
+       into some round spaces called <i>vacuoles</i> which are
+       dotted over the body of the animal, and are really globules
+       of watery fluid in which the food is probably partly
+       digested.</p>
+
+    <p>You will notice, however, one round clear space <i>(cv)</i>
+    into which they do not go, and after a time you will be able to
+    observe that this round spot closes up or contracts very
+    quickly, and then expands again very slowly. As it expands it
+    fills with a clear fluid, and naturalists have not yet decided
+    exactly what work it does. It may serve the animal either for
+    breathing, or as a very simple heart, making the fluids
+    circulate in the tube. The next interesting point about this
+    little being is the way it retreats into its sheltering vase.
+    Even while you are watching, it is quite likely it may all at
+    once draw itself down to the bottom as in No. 2, and folding
+    down the valves <i>w</i> of horny teeth which grow on each
+    side, shut itself in from some fancied danger. Another very
+    curious point is that, besides sending forth young ones, these
+    creatures multiply by dividing in two (see No. 3, Fig. 6), each
+    one closing its own part of the vase into a new home.</p>
+
+    <p>There are hundreds of these Infusoria, as they are called,
+    in my pond, some with vases, some without, some fixed to weeds
+    and stones, others swimming about freely. Even in the
+    water-trough in which this Thuricolla stands, I saw several
+    smaller forms, and the next microscope has a trough filled with
+    the minutest form of all, called a Monad. These are so small
+    that two thousand of them could lie side by side in an inch;
+    <span class="pagenum"><a name="page376"
+       id="page376"></a>[pg 376]</span> that is, if you could make
+       them lie at all, for they are the most restless little
+       beings, darting hither and thither, scarcely even halting
+       except to turn back. And yet though there are so many of
+       them, and as far as we know they have no organs of sight,
+       they never run up against each other, but glide past more
+       cleverly than any clear-sighted fish. These creatures are
+       mostly to be found among decaying seaweed, and though they
+       are so tiny, you can still see distinctly the clear space
+       contracting and expanding within them.</p>
+
+    <div class="figleft"
+         style="width:350px;">
+        <a href="images/376.png"><img width="350"
+             src="images/376.png"
+             alt="FIG. 7. LIVING DIATOMS." /></a><br />
+        FIG. 7. LIVING DIATOMS.
+
+        <p><i>a, Cocconema lanceolatum. b, Bacillaria paradoxa. c,
+        Gomphonema marinum. d, Diatoma hyalina</i>.</p>
+    </div>
+
+    <p>But if there are so many thousands of mouths to feed, on the
+    tree-like Sertulariæ as well as in all these Infusoria, where
+    does the food come from? Partly from the numerous atoms of
+    decaying life all around, and the minute eggs of animals and
+    spores of plants; but besides these, the pool is full of minute
+    living plants&mdash;small jelly masses with solid coats of
+    flint which are moulded into most lovely shapes. Plants formed
+    of jelly and flint! You will think I am joking, but I am not.
+    These plants, called Diatoms, which live both in salt and fresh
+    water, are single cells feeding and growing just like those we
+    took from the water-butt, only that instead of a soft covering
+    they build up <span class="pagenum"><a name="page377"
+       id="page377"></a>[pg 377]</span> a flinty skeleton. They are
+       so small, that many of them must be magnified to fifty times
+       their real size before you can even see them distinctly. Yet
+       the skeletons of these almost invisible plants are carved
+       and chiselled in the most delicate patterns. I showed you a
+       group of these in our lecture on magic glasses, and now I
+       have brought a few living ones that we may learn to know
+       them. The diagram (Fig. 7) shows the chief forms you will
+       see on the different slides.</p>
+
+    <p>The first one, <i>Sacillaria paradoxa</i> (<i>b</i>, Fig.
+    7), looks like a number of rods clinging one to another in a
+    string, but each one of these is a single-celled plant with a
+    jelly cell surrounding the flinty skeleton. You will see that
+    they move to and fro over each other in the water.</p>
+
+    <p>The next two forms, <i>a</i> and <i>c</i>, look much more
+    like plants, for the cells arrange themselves on a jelly stem,
+    which by and by disappears, leaving only the separate flint
+    skeletons. The last form, <i>d</i>, is something midway between
+    the other forms, the separate cells hang on to each other and
+    also on to a straight jelly stem.</p>
+
+    <div class="figright"
+         style="width:175px;">
+        <a href="images/377.png"><img width="175"
+             src="images/377.png"
+             alt="FIG. 8. A DIATOM" /></a>
+
+        <p>FIG. 8. A DIATOM (<i>Diatoma vulgare</i>) GROWING.</p>
+
+        <p><i>a, b,</i> Flint skeleton inside the jelly-cell. <i>a,
+        c</i> and <i>d, b</i>, Two flint skeletons formed by new
+        valves, <i>c</i> and <i>d</i>, forming within the first
+        skeleton.</p>
+    </div>
+
+    <p>Another species of Diatoma (Fig. 8) called <i>Diatoma
+    vulgare</i>, is a very simple and common form, and will help to
+    explain how these plants grow. The two flinty valves <i>a,
+    b</i> inside the cell are not quite the same size; the older
+    one <i>a</i> is larger than the younger one <i>b</i> and fits
+    over it like the cover of a pill-box. As the plant grows, the
+    cell enlarges and forms two <span class="pagenum"><a name=
+    "page378"
+       id="page378"></a>[pg 378]</span> more valves, one <i>c</i>
+       fitting into the cover <i>a</i>, so as to make a complete
+       box <i>ac</i>, and a second, <i>d</i>, back to back with
+       <i>c</i>, fitting into the valve <i>b</i>, and making
+       another complete <i>bd</i>. This goes on very rapidly, and
+       in this plant each new cell separates as it is formed, and
+       the free diatoms move about quite actively in the water.</p>
+
+    <p>If you consider for a moment, you will see that, as the new
+    valves always fit into the old ones, each must be smaller than
+    the last, and so there comes a time when the valves have become
+    too small to go on increasing. Then the plant must begin
+    afresh. So the two halves of the last cell open, and throwing
+    out their flinty skeletons, cover themselves with a thin jelly
+    layer, and form a new cell which grows larger than any of the
+    old ones. These, which are spore-cells, then form flinty valves
+    inside, and the whole thing begins again.</p>
+
+    <p>Now, though the plants themselves die, or become the food of
+    minute animals, the flinty skeletons are not destroyed, but go
+    on accumulating in the waters of the ponds, lakes, rivers, and
+    seas, all over the world. Untold millions have no doubt
+    crumbled to dust and gone back into the waters, but untold
+    millions also have survived. The towns of Berlin in Europe and
+    of Richmond in the United States are actually built upon ground
+    called "infusorial earth," composed almost entirely of valves
+    of these minute diatoms which have accumulated to a thickness
+    of more than eighty feet! Those under Berlin are fresh-water
+    forms, and must have lived in a lake, while those of Richmond
+    belong to salt-water forms. Every inch of the ground under
+    those cities represents thousands and thousands of living
+    plants <span class="pagenum"><a name="page379"
+       id="page379"></a>[pg 379]</span> which flourished in ages
+       long gone by, and were no larger than those you will see
+       presently under the microscope.</p>
+
+    <p>These are a very few of the microscopic inhabitants of my
+    pond, but, as you will confuse them if I show you too many, we
+    will conclude with two rather larger specimens, and examine
+    them carefully. The first, called the Cydippe, is a lovely,
+    transparent living ball, which I want to explain to you because
+    it is so wondrously beautiful. The second, the Sea-mat or
+    Flustra, looks like a crumpled drab-colored seaweed, but is
+    really composed of many thousands of grottos, the homes of tiny
+    sea-animals.</p>
+
+    <div class="figcenter"
+         style="width:500px;">
+        <a href="images/379.jpg"><img width="500"
+             src="images/379.jpg"
+             alt="FIG. 9. Cydippe Pileus." /></a><br />
+        FIG. 9. <i>Cydippe Pileus</i>.
+
+        <p>1, Animal with tentacles <i>t</i>, bearing small
+        tendrils <i>t'</i>. 2, Body of animal enlarged. <i>m</i>,
+        Mouth. <i>c</i>, Digestive cavity. <i>s</i>, Sac into which
+        the tentacles are withdrawn. <i>p</i>, Bands with comb-like
+        plates. 3, Portion of a band enlarged to show the moving
+        plates <i>p</i>.</p>
+    </div>
+
+    <p>Let us take the Cydippe first (1, Fig. 9). I have six here,
+    each in a separate tumbler, and could have brought many more,
+    for when I dipped my net in the pool yesterday such numbers
+    were caught in it that I believe the retreating tide must just
+    have left a shoal behind. Put a tumbler on the desk in front of
+    you, <span class="pagenum"><a name="page380"
+       id="page380"></a>[pg 380]</span> and if the light falls well
+       upon it you will see a transparent ball about the size of a
+       large pea marked with eight bright bands, which begin at the
+       lower end of the ball and reach nearly to the top, dividing
+       the outside into sections like the ribs of a melon. The
+       creature is so perfectly transparent that you can count all
+       the eight bands.</p>
+
+    <p>At the top of the ball is a slight bulge which is the mouth
+    (<i>m</i> 2, Fig. 9), and from it, inside the ball hangs a long
+    bag or stomach, which opens below into a cavity, from which two
+    canals branch out, one on each side, and these divide again
+    into four canals which go one into each of the tubes running
+    down the bands. From this cavity the food, which is digested in
+    the stomach, is carried by the canals all over the body. The
+    smaller tubes which branch out of these canals cannot be seen
+    clearly without a very strong lens, and the only other parts
+    you can discern in this transparent ball are two long sacs on
+    each side of the lower end. These are the tentacle sacs, in
+    which are coiled up the tentacles, which we shall describe
+    presently. Lastly you can notice that the bands outside the
+    globe are broader in the middle than at the ends, and are
+    striped across by a number of ridges.</p>
+
+    <p>In moving the tumblers the water has naturally been shaken,
+    and the creature being alarmed will probably at first remain
+    motionless. But very soon it will begin to play in the water,
+    rising and falling, and swimming gracefully from side to side.
+    Now you will notice a curious effect, for the bands will
+    glitter and become tinged with prismatic colors, till, as it
+    moves more and more rapidly these colors, reflected in the
+    jelly, seem <span class="pagenum"><a name="page381"
+       id="page381"></a>[pg 381]</span> to tinge the whole ball
+       with colors like those on a soap-bubble, while from the two
+       sacs below come forth two long transparent threads like spun
+       glass. At first these appear to be simple threads, but as
+       they gradually open out to about four or five inches,
+       smaller threads uncoil on each side of the line till there
+       are about fifty on each line. These short tendrils are never
+       still for long; as the main threads wave to and fro, some of
+       the shorter ones coil up and hang like tiny beads, then
+       these uncoil and others roll up, so that these graceful
+       floating lines are never two seconds alike.</p>
+
+    <p>We do not really know their use. Sometimes the creature
+    anchors itself by them, rising and falling as they stretch out
+    or coil up; but more often they float idly behind it in the
+    water. At first you would perhaps think that they served to
+    drive the ball through the water, but this is done by a special
+    apparatus. The cross ridges which we noticed on the bands are
+    really flat comb-like plates (<i>p</i>, Fig. 9), of which there
+    are about twenty or thirty on each band; and these vibrate very
+    rapidly, so that two hundred or more paddles drive the tiny
+    ball through the water. This is the cause of the prismatic
+    colors; for iridescent tints are produced by the play of light
+    upon the glittering plates, as they incessantly change their
+    angle. Sometimes they move all at once, sometimes only a few at
+    a time, and it is evident the creature controls them at
+    will.</p>
+
+    <p>This lovely fairy-like globe, with its long floating
+    tentacles and rainbow tints, was for a long time classed with
+    the jelly-fish; but it really is most nearly related to the
+    sea-anemones, as it has a true central cavity which acts as a
+    stomach, and many other points in common <span class=
+    "pagenum"><a name="page382"
+       id="page382"></a>[pg 382]</span> with the <i>Actinozoa</i>.
+       We cannot help wondering, as the little being glides hither
+       and thither, whether it can see where it is going. It has
+       nerves of a low kind which start from a little dark spot
+       (<i>ng</i>) exactly at the south pole of the ball, and at
+       that point a sense-organ of some kind exists, but what
+       impression the creature gains from it of the world outside
+       we cannot tell.</p>
+
+    <p>I am afraid you may think it dull to turn from such a
+    beautiful being as this, to the gray leaf which looks only like
+    a dead dry seaweed; yet you will be wrong, for a more wonderful
+    history attaches to this crumpled dead-looking leaf than to the
+    lovely jelly-globe.</p>
+
+    <div class="figleft"
+         style="width:300px;">
+        <a href="images/382.png"><img width="300"
+             src="images/382.png"
+             alt="FIG. 10. THE SEA-MAT OR FLUSTRA." /></a>
+
+        <p>FIG. 10. THE SEA-MAT OR FLUSTRA (<i>Flustra
+        foliacea</i>).</p>
+
+        <p>1, Natural size. 2, Much magnified, <i>s</i>, Slit
+        caused by drawing in of the animal <i>a</i>.</p>
+    </div>
+
+    <p>First of all I will pass round pieces of the dry leaf (1,
+    Fig. 10), and while you are getting them I will tell you where
+    I found the living ones. Great masses of the Flustra, as it is
+    called, line the bottom and sides of my pool. They grow in
+    tufts, standing upright on the rock, and looking exactly like
+    hard gray seaweeds, while there is nothing to lead you to
+    suspect that they are anything else. Yesterday I chipped off
+    very carefully a piece of rock with a tuft upon it, and have
+    kept it since in a glass globe by itself with sea-water, for
+    the little creatures living in this marine city require a very
+    good supply of healthy water and air. I have called it a
+    "marine <span class="pagenum"><a name="page383"
+       id="page383"></a>[pg 383]</span> city," and now I will tell
+       you why. Take the piece in your hand and run your finger
+       gently up and down it; you will glide quite comfortably from
+       the lower to the higher part of the leaf, but when you come
+       back you will feel your finger catch slightly on a rough
+       surface. Your pocket lens will show you why this is, for if
+       you look through it at the surface of the leaf you will see
+       it is not smooth, but composed of hundreds of tiny alcoves
+       with arched tops; and on each side of these tops stand two
+       short blunt spines, making four in all, pointing upwards, so
+       as partly to cover the alcove above. As your finger went up
+       it glided over the spines, but on coming back it met their
+       points. This is all you can see in the dead specimen; I must
+       show you the rest by diagrams, and by and by under the
+       microscope.</p>
+
+    <p>First, then, in the living specimen which I have here, those
+    alcoves are not open as in the dead piece, but covered over
+    with a transparent skin, in which, near the top of the alcove
+    just where the curve begins, is a slit (<i>s</i> 2, Fig. 10)
+    Unfortunately, the membrane covering this alcove is too dense
+    for you to distinguish the parts within. Presently, however, if
+    you are watching a piece of this living leaf in a flat
+    water-cell under the microscope, you will see the slit slowly
+    open, and begin to turn as it were inside out, exactly like the
+    finger of a glove, which has been pushed in at the tip,
+    gradually rises up when you put your finger inside it. As this
+    goes on, a bundle of threads appears, at first closed like a
+    bud, but gradually opening out into a crown of tentacles, each
+    one clothed with hairs. Then you will see that the slit was not
+    exactly a slit after all, but the round edge where the sac was
+    <span class="pagenum"><a name="page384"
+       id="page384"></a>[pg 384]</span> pushed in. Ah! you will
+       say, you are now showing me a polyp like those on the
+       sertularian tree. Not so fast, my friend; you have not
+       studied what is still under the covering skin and hidden in
+       the living animal. I have, however, prepared a slide with
+       this membrane removed and there you can observe the
+       different parts, and learn that each one of these alcoves
+       contains a complete animal, and not merely one among many
+       mouths, like the polyp on Sertularia.</p>
+
+    <div class="figleft"
+         style="width:250px;">
+        <a href="images/384.jpg"><img width="250"
+             src="images/384.jpg"
+             alt=
+           "FIG. 11. DIAGRAM OF THE ANIMAL IN THE FLUSTRA OR SEA-MAT." /></a>
+
+        <p>FIG. 11. DIAGRAM OF THE ANIMAL IN THE FLUSTRA OR
+        SEA-MAT.</p>
+
+        <p>1, Animal protruding. 2, Animal retracted in the sheath,
+        <i>sh</i>, Covering sheath, <i>s</i>, Slit. <i>t</i>,
+        Tentacles. <i>m</i>, Mouth. <i>th</i>, Throat, <i>st</i>,
+        Stomach. <i>i</i>, Intestine, <i>r</i>, Retractor muscle,
+        <i>e</i>, Egg-forming parts. <i>g</i>, Nerve-ganglion.</p>
+    </div>
+
+    <p>Each of these little beings (<i>a</i>, Fig. 10) living in
+    its alcove has a mouth, throat, stomach, intestine, muscles,
+    and nerves starting from the ganglion of nervous matter,
+    besides all that is necessary for producing eggs and sending
+    forth young ones. You can trace all these under the microscope
+    (see 2, Fig. 11) as the creature lies curiously doubled up in
+    its bed, with its body bent in a loop; the intestine <i>i</i>,
+    out of which the refuse food passes, coming back close up to
+    the slit. When it is at rest, the top of the sac in which it
+    lies is pulled in by the retractor muscle <i>r</i>, and looks,
+    as I have said, like the finger of a glove with the top pushed
+    in. When it wishes to feed this top is drawn out by muscles
+    running <span class="pagenum"><a name="page385"
+       id="page385"></a>[pg 385]</span> round the sac, and the
+       tentacles open and wave in the water (1, Fig. 11).</p>
+
+    <p>Look now at the alcoves, the homes of these animals; see how
+    tiny they are and how closely they fit together. Mr. Gosse, the
+    naturalist, has reckoned that there are six thousand, seven
+    hundred and twenty alcoves in a square inch; then if you turn
+    the leaf over you will see that there is another set, fixed
+    back to back with these, on the other side, making in all,
+    thirteen thousand, four hundred and forty alcoves. Now a
+    moderate-sized leaf of flustra measures about three square
+    inches, taking all the rounded lobes into account, so you will
+    see we get forty thousand, three hundred and twenty as a rough
+    estimate of the number of beings on this one leaf. But if you
+    look at this tuft I have brought, you will find it is composed
+    of twelve such leaves, and this after all is a very small part
+    of the mass growing round my pool. Was I wrong, then, when I
+    said my miniature ocean contains as many millions of beings as
+    there are stars in the heavens?</p>
+
+    <p>You will want to know how these leaves grew, and it is in
+    this way. First a little free swimming animal, a mere living
+    sac provided with lashes, settles down and grows into one
+    little horny alcove, with its live creature inside, which in
+    time sends off from it three to five buds, forming alcoves all
+    round the top and sides of the first one, growing on to it.
+    These again bud out, and you can thus easily understand that,
+    in this way, in time a good-sized leaf is formed. Meanwhile the
+    creatures also send forth new swimming cells, which settle down
+    near to begin new leaves, and thus <span class=
+    "pagenum"><a name="page386"
+       id="page386"></a>[pg 386]</span> a tuft is formed; and long
+       after the beings in earlier parts of the leaf have died and
+       left their alcoves empty, those round the margin are still
+       alive and spreading....</p>
+
+    <p>If you can trace the spore-cells and urns in the seaweeds,
+    observe the polyps in the Sertularia, and count the number of
+    mouths on a branch of my animal fringe (Sertularia tenella); if
+    you make acquaintance with the Thuricolla in its vase, and are
+    fortunate enough to see one divide in two; if you learn to know
+    some of the beautiful forms of diatoms, and can picture to
+    yourself the life of the tiny inhabitants of the Flustra; then
+    you will have used your microscope with some effect, and be
+    prepared for an expedition to my pool, where we will go
+    together some day to seek new treasures.</p>
+
+    <div class="figcenter"
+         style="width:400px;">
+        <a href="images/386.png"><img width="400"
+             src="images/386.png"
+             alt="page decoration" /></a>
+    </div>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="page387"
+       id="page387"></a>[pg 387]</span>
+
+    <h2>NOTES</h2>
+
+    <p><span class="sc">Agassiz, J.L.R.</span>, naturalist, born in
+    Switzerland, 1807; died, Cambridge, Mass., 1873. In 1846 he
+    came to America, after having gained a high reputation in
+    Europe, to deliver a course of lectures in Boston "On the Plan
+    of the Creation," and met with such success that he spent the
+    rest of his days there, declining an invitation to return to
+    his native country and to Paris. In 1848 he was elected to the
+    chair of Natural History at Harvard. In 1850-51 he went on an
+    expedition to the Florida Reefs. In 1858 he founded and
+    organized the Museum of Comparative Zoölogy at
+    Cambridge&mdash;and, later on, went on his important voyage to
+    Brazil. In 1872 he founded and organized the summer school of
+    Natural History at Buzzard's Bay. He wrote "The Fishes of
+    Brazil," "A Study of Glaciers," "Natural History of the Fresh
+    Water Fishes of Central Europe," "Contributions to the Natural
+    History of the United States" (unfinished), and with his wife,
+    "A Journey in Brazil."</p>
+
+    <p><span class="sc">Ball, Prof. Sir R.S.</span>, English
+    astronomer, born in Dublin, 1840. Was appointed Lord Ross's
+    astronomer in 1865. Professor of mathematics and mechanics at
+    the Royal Irish College of Science in 1873, and is now
+    astronomer royal for Ireland. He is the author of "The Story of
+    the Heavens," "Starland," etc., and is well known as a
+    successful lecturer on astronomical subjects in this
+    country.</p>
+
+    <p><span class="sc">Darwin, Charles R.</span>, English
+    naturalist, born, 1809; died, 1882. He first formulated what is
+    known as the principle of Natural Selection. In 1831 he went in
+    the famous scientific voyage of the <i>Beagle</i> as
+    naturalist, and afterwards published an account of it. He was
+    one of the most thorough, careful, and painstaking scientific
+    men of this or any age. He is the author of many famous books.
+    "The Origin of Species," "The Descent of Man," "Insectivorous
+    Plants," "The Power of Movement in Plants," "The Structure and
+    Distribution of Coral Reefs," "Geological Observations on
+    Volcanic Islands." "The Formation of Vegetable Mould" was his
+    last published work.</p>
+
+    <p><span class="sc">Flammarion, C.</span>, famous French
+    astronomer, born, 1842. He has written many popular works on
+    astronomy, most of which have been translated into English.
+    "The Stars," "The World Before the Creation," "Uranus,"
+    "Comets," "Popular Astronomy," are among his best known.</p>
+
+    <p><span class="sc">Holden, Prof. E.S.</span>, American
+    astronomer, born at St. Louis, 1846. Lieutenant engineers,
+    U.S.A., 1870-73; professor mathematics, U.S.N., 1873-81;
+    director Washburn Observatory, 1881-85; president University of
+    California, 1883-88; director Lick Observatory, 1888-98. Is a
+    member of several learned societies of Europe. Is the author of
+    a "Life of William Herschel," "A Hand-book of the Lick
+    Observatory," "Earth and Sky," "Primer of Heraldry,"
+    "Elementary Astronomy," "Family of the Sun," "Essays in
+    Astronomy," "Stories of the Great Astronomers," etc.</p>
+
+    <p><span class="sc">Huxley, T.H.</span>, English biologist,
+    born, 1825; died, 1895. Went on an exploring expedition on the
+    <i>Rattlesnake</i>, and devoted himself to the study of marine
+    life. For his scientific researches he received many honors.
+    His lectures were models of clearness, and he could simplify
+    the most difficult subjects. He strongly advocated Darwin's
+    views and evolutionist doctrines. His writings are numerous and
+    many of them technical. Among some of the most popular are
+    "Man's Place in Nature," his "Lay Sermons," "Critiques and
+    Addresses," "American Addresses," "Physiography," "Science and
+    Culture," "Lessons in Elementary Physiology,"
+    etc.</p><span class="pagenum"><a name="page388"
+       id="page388"></a>[pg 388]</span>
+
+    <p><span class="sc">Kingsley, C.</span>, English clergyman and
+    author, born, 1819; died, 1875. Wrote "Westward, Ho!" which
+    every boy should read, "Hypatia," "Alton Locke," "Hereward the
+    Wake," etc., and a charming book of travel, entitled, "At
+    Last." His "Water Babies" is exceedingly popular, and his
+    "Heroes" is a book much appreciated by the boys and girls
+    alike.</p>
+
+    <p><span class="sc">Proctor, R.A.</span>, English astronomer,
+    born, 1834; died, 1888. He was a very popular writer, and
+    lectured on astronomical subjects in this country, and in
+    England and her colonies. A memorial teaching observatory is
+    erected in his honor near San Diego, Cal. He was a man of
+    untiring industry, an athlete, a musician, and a chess-player.
+    His books are numerous. Among them are "Half Hours with the
+    Telescope," "Other Worlds than Ours," "Light Science for
+    Leisure Hours," "The Expanse of Heaven," "The Moon," "The
+    Borderland of Science," "Our Place Among Infinites," "Myths and
+    Marvels of Astronomy," "The Universe of Suns," "Other Suns than
+    Ours," etc.</p>
+
+    <p><span class="sc">Shaler, N.S.</span>, professor of geology
+    at Harvard. Born Newport, Ky., 1841. Served in the Union Army
+    during the Civil War. Instructor zoölogy, geology, and
+    paleontology, Lawrence Scientific School, till 1887. Since then
+    at Harvard. Is the author of "Kentucky a Pioneer Commonwealth,"
+    "The Story of Our Continent," "The Interpretation of Nature,"
+    "Feature of Coasts and Oceans," "Domesticated Animals," "The
+    Individual," "Study of Life and Death," etc.</p>
+
+    <p><span class="sc">Thompson, Sir C. Wyville</span>, English
+    zoölogist, born, 1830; died, 1882. He conducted scientific
+    dredging expeditions in the <i>Lightning</i> and
+    <i>Porcupine</i>, 1868-69, and was the scientific head of the
+    famous voyage of 68,900 miles in the <i>Challenger</i> for
+    deep-sea explorations (1872-76). His books are "The Depths of
+    the Sea," and "The Voyage of the Challenger."</p>
+
+    <p><span class="sc">Tyndall, John</span>, English physicist,
+    born, 1820. Began his original researches in 1847, when teacher
+    of physics in Queenwood College. He and Professor Huxley
+    visited the Alps together, and they wrote a work on the
+    structure and nature of glaciers. It is impossible to detail
+    the work he has done; but his inquiries and experiments in
+    connection with light, heat, sound, and electricity have all
+    had practical results. He is a popular lecturer, and devoted
+    the proceeds of a lecturing tour in this country to founding
+    scholarships at Harvard and Columbia Colleges, for students
+    devoting themselves to original research. Among his books are
+    "Glaciers of the Alps," "Mountaineering," "Heat as a Mode of
+    Motion," "On Radiation," "Hours of Exercise in the Alps,"
+    "Fragments of Science," "The Floating Matter of the Air," and
+    volumes on Light, Sound, Electricity, and the forms of
+    water.</p>
+
+    <p><span class="sc">Wallace, A.R.</span>, English naturalist
+    and traveller, born 1822; was educated as land surveyor and
+    architect, but afterwards devoted himself entirely to Natural
+    History. He explored the Valley of the Amazon and Rio Negro,
+    1848-52, and travelled in the Malay Archipelago and Papua,
+    1854-62, publishing the results of his explorations later on.
+    He also wrote "Contributions to the Theory of Natural
+    Selection," "Miracles and Modern Spiritualism," "Geographical
+    Distribution of Animals," "Tropical Nature," "Island Life,"
+    etc.</p>
+
+    <p><span class="sc">Giberne, Agnes</span>, English
+    author&mdash;living. Began to write at seven years old. Her
+    first story for children was published when she was only
+    seventeen. Her stories for children have not been so popular as
+    her scientific writings, "Sun, Moon, and Stars," "The Starry
+    Skies," "Among the Stars," "The Ocean of Air," "The World's
+    Foundations," "Radiant Suns," etc.</p>
+
+    <p><span class="sc">Wilson, Andrew</span>, English physiologist
+    and lecturer, born, 1852. Is the author of "Studies on Life and
+    Sense," "Leisure Time Studies," "Science Stories," "Chapters on
+    Evolution," "Wild Animals," "Brain and Nerve," etc., and is a
+    constant contributor on scientific subjects to the magazines
+    and newspapers, contributing weekly "Science Jottings" to the
+    "Illustrated London News"</p>
+
+    <p>&nbsp;</p>
+
+    <p>&nbsp;</p><span class="pagenum"><a name="page389"
+       id="page389"></a>[pg 389]</span>
+
+    <h2>WONDERS OF EARTH, SEA, AND SKY</h2>
+
+    <h3>SUGGESTIONS FOR SUPPLEMENTARY READING</h3>
+
+    <div class="poem">
+        <div class="stanza">
+            <p>Wonder Stories of Science</p>
+
+            <p class="i2">D.N. BEACH</p>
+        </div>
+
+        <div class="stanza">
+            <p>Wonders in Monsterland</p>
+
+            <p class="i2">EDWARD W.D. CUMING</p>
+        </div>
+
+        <div class="stanza">
+            <p>Ocean Wonders</p>
+
+            <p class="i2">W.E. DAMON</p>
+        </div>
+
+        <div class="stanza">
+            <p>Among the Stars</p>
+
+            <p class="i2">AGNES GIBERNE</p>
+        </div>
+
+        <div class="stanza">
+            <p>The Scenery of the Heavens</p>
+
+            <p class="i2">JOHN ELLARD GORR</p>
+        </div>
+
+        <div class="stanza">
+            <p>Coal and the Coal Miners</p>
+
+            <p class="i2">HOMER GREENE</p>
+        </div>
+
+        <div class="stanza">
+            <p>Wonders of the Moon</p>
+
+            <p class="i2">A. GUILLEMIN</p>
+        </div>
+
+        <div class="stanza">
+            <p>The Sea and Its Living Wonders.</p>
+
+            <p class="i2">G. HARTWIG</p>
+        </div>
+
+        <div class="stanza">
+            <p>The Wonders of Plant Life Under the Microscope</p>
+
+            <p class="i2">SOPHIE B. HERRICK</p>
+        </div>
+
+        <div class="stanza">
+            <p>Marvels of Animal Life</p>
+
+            <p class="i2">CHARLES F. HOLDER</p>
+        </div>
+
+        <div class="stanza">
+            <p>Old Ocean</p>
+
+            <p class="i2">ERNEST INGERSOLL</p>
+        </div>
+
+        <div class="stanza">
+            <p>Modern Seven Wonders of the World</p>
+
+            <p class="i2">C. KENT</p>
+        </div>
+
+        <div class="stanza">
+            <p>Madam How and Lady Why</p>
+
+            <p class="i2">CHARLES KINGSLEY</p>
+        </div>
+
+        <div class="stanza">
+            <p>Wonders of Optics</p>
+
+            <p class="i2">F. MARION</p>
+        </div>
+
+        <div class="stanza">
+            <p>The Wonders of Science</p>
+
+            <p class="i2">HENRY MAYHEW</p>
+        </div>
+
+        <div class="stanza">
+            <p>Wonders of Man and Nature</p>
+
+            <p class="i2">E. MENAULT</p>
+        </div>
+
+        <div class="stanza">
+            <p>A Century of Electricity</p>
+
+            <p class="i2">T.C. MENDENHALL</p>
+        </div>
+
+        <div class="stanza">
+            <p>The Orbs of Heaven</p>
+
+            <p class="i2">ORMSBY S. MITCHELL</p>
+        </div>
+
+        <div class="stanza">
+            <p>Under Foot</p>
+
+            <p class="i2">LAURA D. NICHOLS</p>
+        </div>
+
+        <div class="stanza">
+            <p>Myths and Marvels of Astronomy</p>
+
+            <p class="i2">R.A. PROCTOR</p>
+        </div>
+
+        <div class="stanza">
+            <p>The Wonders of the World</p>
+
+            <p class="i2">CHARLES G. ROSENBERG</p>
+        </div>
+
+        <div class="stanza">
+            <p>The Wonders of Nature</p>
+
+            <p class="i2">PROFESSOR RUDOLPH</p>
+        </div>
+
+        <div class="stanza">
+            <p>Volcanoes of North America</p>
+
+            <p class="i2">ISRAEL COOK RUSSELL</p>
+        </div>
+
+        <div class="stanza">
+            <p>Aspects of the Earth</p>
+
+            <p class="i2">N.S. SHALER</p>
+        </div>
+
+        <div class="stanza">
+            <p>Wonders of the Bird World</p>
+
+            <p class="i2">R.B. SHARPE</p>
+        </div>
+
+        <div class="stanza">
+            <p>The Wonders of Water</p>
+
+            <p class="i2">GASTON TISSANDIER</p>
+        </div>
+
+        <div class="stanza">
+            <p>Total Eclipses of the Sun</p>
+
+            <p class="i2">MABEL L. TODD</p>
+        </div>
+
+        <div class="stanza">
+            <p>Wonders of Insect Life</p>
+
+            <p class="i2">JOSEPH C. WILLET</p>
+        </div>
+    </div>
+
+    <p>&nbsp;</p>
+    <hr />
+
+    <blockquote class="footnote">
+        <a id="footnote1"
+                    name="footnote1"></a><b>Footnote 1:</b>
+                    <a href="#footnotetag1">(return)</a>
+
+        <p>Copyright, 1884, by N.S. Shaler.</p>
+    </blockquote>
+
+    <blockquote class="footnote">
+        <a id="footnote2"
+                    name="footnote2"></a><b>Footnote 2:</b>
+                    <a href="#footnotetag2">(return)</a>
+
+        <p>During the cruise of H.M.S. Bull-dog, commanded by Sir
+        Leopold M'Clintock, in 1860, living star-fish were brought
+        up, clinging to the lowest part of the sounding-line, from
+        a depth of 1260 fathoms, midway between Cape Farewell, in
+        Greenland, and the Rockall banks. Dr. Wallich ascertained
+        that the sea-bottom at this point consisted of the ordinary
+        Globigerina ooze, and that the stomachs of the star-fishes
+        were full of Globigerinæ. This discovery removes all
+        objections to the existence of living Globigerinæ at great
+        depths, which are based upon the supposed difficulty of
+        maintaining animal life under such conditions; and it
+        throws the burden of proof upon those who object to the
+        supposition that the Globigerinæ live and die where they
+        are found.</p>
+    </blockquote>
+
+    <blockquote class="footnote">
+        <a id="footnote3"
+                    name="footnote3"></a><b>Footnote 3:</b>
+                    <a href="#footnotetag3">(return)</a>
+
+        <p>I have recently traced out the development of the
+        "coccoliths" from a diameter of 1/7000th of an inch up to
+        their largest size (which is about 1/1600th), and no longer
+        doubt that they are produced by independent organisms,
+        which, like the Globigerinæ, live and die at the bottom of
+        the sea.</p>
+    </blockquote>
+
+    <blockquote class="footnote">
+        <a id="footnote4"
+                    name="footnote4"></a><b>Footnote 4:</b>
+                    <a href="#footnotetag4">(return)</a>
+
+        <p>The slice given in Fig. 2 is from a broader-leaved form,
+        <i>U. lactuca</i>, because this species, being composed of
+        only one layer of cells, is better seen. <i>Ulva Linza</i>
+        is composed of two layers of cells.</p>
+    </blockquote>
+
+<p>&nbsp;</p>
+<hr class="full" />
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diff --git a/old/20050523-15884.txt b/old/20050523-15884.txt
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--- /dev/null
+++ b/old/20050523-15884.txt
@@ -0,0 +1,11043 @@
+The Project Gutenberg eBook, Young Folks' Library, Volume XI (of 20), by
+Various, Edited by Edward Singleton Holden
+
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+
+
+
+Title: Young Folks' Library, Volume XI (of 20)
+       Wonders of Earth, Sea and Sky
+
+
+Author: Various
+
+Editor: Edward Singleton Holden
+
+Release Date: May 23, 2005  [eBook #15884]
+
+Language: English
+
+Character set encoding: ISO-646-US (US-ASCII)
+
+
+***START OF THE PROJECT GUTENBERG EBOOK YOUNG FOLKS' LIBRARY, VOLUME XI
+(OF 20)***
+
+
+E-text prepared by Juliet Sutherland, Sandra Brown, and the Project
+Gutenberg Online Distributed Proofreading Team
+
+
+
+Note: Project Gutenberg also has an HTML version of this
+      file which includes the original illustrations.
+      See 15884-h.htm or 15884-h.zip:
+      (https://www.gutenberg.org/dirs/1/5/8/8/15884/15884-h/15884-h.htm)
+      or
+      (https://www.gutenberg.org/dirs/1/5/8/8/15884/15884-h.zip)
+
+
+
+
+
+Young Folks' Library
+
+Selections from the Choicest Literature of All
+Lands; Folk-Lore, Fairy Tales, Fables, Legends,
+Natural History, Wonders of Earth, Sea
+and Sky, Animal Stories, Sea Tales,
+Brave Deeds, Explorations, Stories
+of School and College Life,
+Biography, History, Patriotic
+Eloquence, Poetry
+
+Third Edition
+
+Revised in Conference by
+
+   Thomas Bailey Aldrich, Editor-in-Chief,
+   President William Jewett Tucker,
+   Hamilton Wright Mabie,
+   Henry Van Dyke,
+   Nathan Haskell Dole
+
+Twenty Volumes   Richly Illustrated
+
+Boston
+Hall and Locke Company
+Publishers
+Stanhope Press
+F.H. Gilson Company
+Boston, U.S.A.
+
+1902
+
+
+
+
+
+
+EDITORIAL BOARD
+
+
+   THOMAS BAILEY ALDRICH, Editor-in-chief,
+   Author, poet, former editor _Atlantic Monthly,_ Boston, Mass.
+
+   The HON. JOHN D. LONG,
+   Secretary of the United States Navy, Boston.
+
+   HAMILTON WRIGHT MABIE, LL.D.,
+   Author, literarian, associate editor _The Outlook_, New York.
+
+   ERNEST THOMPSON SETON,
+   Artist, author, New York.
+
+   JOHN TOWNSEND TROWBRIDGE,
+   Author, poet, and editor, Arlington, Mass.
+
+   The REVEREND CYRUS TOWNSEND BRADY,
+   Archdeacon, author, Philadelphia.
+
+   JOEL CHANDLER HARRIS,
+   Humorous writer, Atlanta, Ga.
+
+   MARY HARTWELL CATHERWOOD,
+   Historical novelist, Chicago.
+
+   LAURA E. RICHARDS,
+   Author, Gardiner, Me.
+
+   ROSWELL FIELD,
+   Author, editor _The Evening Post>_, Chicago.
+
+   TUDOR JENKS,
+   Author, associate editor _Saint Nicholas_, New York.
+
+   GEORGE A. HENTY,
+   Traveller, author, London, England.
+
+   KIRK MUNROE,
+   Writer of stories for boys, Cocoanut Grove, Fla.
+
+   EDITH M. THOMAS,
+   Poet, West New Brighton, N.Y.
+
+   CAROLINE TICKNOR,
+   Author, editor, Boston.
+
+   NATHAN HASKELL DOLE,
+   Author, translator, literary editor _Current History_, Boston.
+
+   WILLIAM RAINEY HARPER, D.D., LL.D.,
+   President Chicago University.
+
+   DAVID STARR JORDAN, M.D., LL.D.,
+   President Leland Stanford Junior University, naturalist, writer,
+   Stanford University, Cal.
+
+   CHARLES ELIOT NORTON, A.M., LL.D., etc.,
+   Scholar, author, Emeritus Professor of Art at Harvard University.
+
+   HENRY VAN DYKE, D.D., LL.D.,
+   Clergyman, author, Professor Princeton University.
+
+   The REVEREND THOMAS J. SHAHAN,
+   Dean of the Faculty of Divinity, Professor of Early Ecclesiastical
+   History, Catholic University, Washington, D.C.
+
+   WILLIAM P. TRENT,
+   Author, editor, Professor of English Literature, Columbia University,
+   New York City.
+
+   EDWARD SINGLETON HOLDEN, A.M., LL.D.,
+   Ex-president University of California, astronomer, author,
+   U.S. Military Academy, West Point.
+
+   EDWIN ERLE SPARKS,
+   Professor of American History, Chicago University.
+
+   The VERY REV. GEORGE M. GRANT, D.D., LL.D.,
+   Educator, author, vice-principal Queen's College, Kingston, Ont.
+
+   BARONESS VON BULOW,
+   Educator, author, Dresden, Germany.
+
+   ABBIE FARWELL BROWN,
+   Author, Boston.
+
+   CHARLES WELSH, Managing Editor,
+   Author, lecturer, editor, Winthrop Highlands, Mass.
+
+
+
+
+
+LIST OF VOLUMES
+
+
+   VOLUME I.
+
+   THE STORY TELLER
+   Edited by CHARLES ELIOT NORTON
+
+
+   VOLUME II.
+
+   THE MERRY MAKER
+   Edited by JOEL CHANDLER HARRIS
+
+
+   VOLUME III.
+
+   FAMOUS FAIRY TALES
+   Edited by ROSWELL FIELD
+
+
+   VOLUME IV.
+
+   TALES OF FANTASY
+   Edited by TUDOR JENKS
+
+
+   VOLUME V.
+   MYTHS AND LEGENDS
+   Edited by THOMAS J. SHAHAN
+
+
+   VOLUME VI.
+
+   THE ANIMAL STORY BOOK
+   Edited by ERNEST THOMPSON SETON
+
+
+   VOLUME VII.
+
+   SCHOOL AND COLLEGE DAYS
+   Edited by KIRK MUNROE and
+   MARY HARTWELL CATHERWOOD
+
+
+   VOLUME VIII.
+
+   BOOK OF ADVENTURE
+   Edited by NATHAN HASKELL DOLE
+
+
+   VOLUME IX.
+
+   FAMOUS EXPLORERS
+   Edited by EDWIN ERLE SPARKS
+
+
+   VOLUME X.
+
+   BRAVE DEEDS
+   Edited by JOHN TOWNSEND TROWBRIDGE
+
+
+   VOLUME XI.
+
+   WONDERS OF EARTH, SEA AND SKY
+   Edited by EDWARD SINGLETON HOLDEN
+
+
+   VOLUME XII.
+
+   FAMOUS TRAVELS
+   Edited by GEORGE A. HENTY
+
+
+   VOLUME XIII.
+
+   SEA STORIES
+   Edited by CYRUS TOWNSEND BRADY
+
+
+   VOLUME XIV.
+
+   A BOOK OF NATURAL HISTORY
+   Edited by DAVID STARR JORDAN
+
+
+   VOLUME XV.
+
+   HISTORIC SCENES IN FICTION
+   Edited by HENRY VAN DYKE
+
+
+   VOLUME XVI.
+
+   FAMOUS BATTLES BY LAND AND SEA
+   Edited by JOHN D. LONG
+
+
+   VOLUME XVII.
+
+   MEN WHO HAVE RISEN
+   Edited by HAMILTON WRIGHT MABIE.
+
+
+   VOLUME XVIII.
+
+   BOOK OF PATRIOTISM
+   Edited by
+
+
+   VOLUME XIX.
+
+   LEADERS OF MEN, OR HISTORY TOLD IN BIOGRAPHY
+   Edited by WILLIAM RAINEY HARPER
+
+
+   VOLUME XX.
+
+   FAMOUS POEMS
+   Selected by THOMAS BAILEY ALDRICH,
+   with Poetical Foreword by EDITH M. THOMAS.
+
+
+
+[Illustration: A GEYSER]
+
+
+
+
+
+Volume XI: WONDERS OF EARTH, SEA AND SKY
+
+Edited by EDWARD SINGLETON HOLDEN
+
+Boston
+Hall and Locke Company Publishers
+
+1902
+
+
+
+
+
+CONTENTS
+
+
+  LIST OF ILLUSTRATIONS                xi
+
+  THE MARVELS OF NATURE              xiii
+  BY PROFESSOR E.S. HOLDEN.
+
+  WHAT THE EARTH'S CRUST IS MADE OF     1
+  BY AGNES GIBERNE.
+
+  AMERICA THE OLD WORLD                45
+  BY LOUIS AGASSIZ.
+
+  SOME RECORDS OF THE ROCKS            77
+  BY N.S. SHALER.
+
+  THE PITCH LAKE IN THE WEST INDIES    97
+  BY CHARLES KINGSLEY.
+
+  A STALAGMITE CAVE                   111
+  BY SIR C. WYVILLE THOMSON.
+
+  THE BIG TREES OF CALIFORNIA         119
+  BY ALFRED RUSSEL WALLACE.
+
+  WHAT IS EVOLUTION?                  127
+  BY PROFESSOR EDWARD S. HOLDEN.
+
+  HOW THE SOIL IS MADE                135
+  BY CHARLES DARWIN.
+
+  ZOOeLOGICAL MYTHS                    143
+  BY ANDREW WILSON.
+
+  ON A PIECE OF CHALK                 171
+  BY T.H. HUXLEY.
+
+  A BIT OF SPONGE                     205
+  BY A. WILSON.
+
+  THE GREATEST SEA-WAVE EVER KNOWN    211
+  BY R.A. PROCTOR.
+
+  THE PHOSPHORESCENT SEA              228
+  BY W.S. DALLAS.
+
+  COMETS                              251
+  BY CAMILLE FLAMMARION.
+
+  THE TOTAL SOLAR ECLIPSE OF 1883     261
+  BY E.S. HOLDEN.
+
+  HALOS--PARHELIA--THE SPECTRE OF
+    THE BROCKEN, ETC.                 268
+  BY CAMILLE FLAMMARION.
+
+  THE PLANET VENUS                    282
+  BY AGNES M. CLERKE.
+
+  THE STARS                           296
+  BY SIR R.S. BALL.
+
+  RAIN AND SNOW                       342
+  BY JOHN TYNDALL.
+
+  THE ORGANIC WORLD                   357
+  BY ST. GEORGE MIVART.
+
+  INHABITANTS OF MY POOL              366
+  BY ARABELLA B. BUCKLEY.
+
+  BIOGRAPHICAL NOTES.                 387
+
+  SUGGESTIONS FOR SUPPLEMENTARY
+    READING.                          389
+
+
+NOTE.
+
+The publishers' acknowledgments are due to Messrs. Houghton, Mifflin &
+Co., for permission to use "America and the Old World," by L. Agassiz;
+to Messrs. D.C. Heath & Co. for permission to use "Some Records of the
+Rocks," by Professor N.S. Shaler; and to Professor E.S. Holden for
+permission to use "What is Evolution?" and "An Astronomer's Voyage to
+Fairy Land."
+
+
+
+
+LIST OF COLORED ILLUSTRATIONS
+
+  A GEYSER. _Frontispiece,  See Page_  47
+
+  VIEW IN A CANON         _Face Page_  12
+
+  A VOLCANO                            48
+
+  A STALAGMITE CAVE                   116
+
+  WHERE SPONGES GROW                  208
+
+  A COMET                             254
+
+  THE SPECTRE OF THE BROCKEN          272
+
+
+AND ONE HUNDRED AND SIXTY-FOUR BLACK AND WHITE ILLUSTRATIONS IN THE
+TEXT.
+
+
+
+
+THE MARVELS OF NATURE
+
+BY EDWARD S. HOLDEN, M.A., Sc.D. LL.D.
+
+
+The Earth, the Sea, the Sky, and their wonders--these are the themes
+of this volume. The volume is so small, and the theme so vast! Men
+have lived on the earth for hundreds of the sands of years; and its
+wonders have increased, not diminished, with their experience.
+
+To our barbarous ancestors of centuries ago, all was mystery--the
+thunder, the rainbow, the growing corn, the ocean, the stars.
+Gradually and by slow steps they learned to house themselves in trees,
+in caves, in huts, in houses; to find a sure supply of food; to
+provide a stock of serviceable clothing. The arts of life were born;
+tools were invented; the priceless boon of fire was received; tribes
+and clans united for defence; some measure of security and comfort was
+attained.
+
+With security and comfort came leisure; and the mind of early Man
+began curiously to inquire the meaning of the mysteries with which he
+was surrounded. That curious inquiry was the birth of Science. Art was
+born when some far-away ancestor, in an idle hour, scratched on a
+bone the drawing of two of his reindeer fighting, or carved on the
+walls of his cave the image of the mammoth that he had but lately
+slain with his spear and arrows.
+
+In a mind that is completely ignorant there is no wonder. Wonder is
+the child of knowledge--of partial and imperfect knowledge, to be
+sure, but still, of knowledge. The very first step in Science is to
+make an inventory of external Nature (and by and by of the faculties
+of the mind that thinks). The second step is to catalogue similar
+appearances together. It is a much higher flight to seek the causes of
+likenesses thus discovered.
+
+A few of the chapters of this volume are items in a mere catalogue of
+wonders, and deserve their place by accurate and eloquent description.
+Most of them, however, represent higher stages of insight. In the
+latter, Nature is viewed not only with the eye of the observer, but
+also with the mind's eye, curious to discover the reasons for things
+seen. The most penetrating inward inquiry accompanies the acutest
+external observation in such chapters as those of Darwin and Huxley,
+here reprinted.
+
+Now, the point not to be overlooked is this: to Darwin and Huxley, as
+to their remote and uncultured ancestors, the World--the Earth, the
+Sea, the Sky--is full of wonders and of mysteries, but the wonders are
+of a higher order. The problems of the thunder and of the rainbow as
+they presented themselves to the men of a thousand generations ago,
+have been fully solved: but the questions; what is the veritable
+nature of electricity, exactly how does it differ from light, are
+still unanswered. And what are simple problems like these to the
+questions: what is love; why do we feel a sympathy with this person,
+an antipathy for that; and others of the sort? Science has made almost
+infinite advances since pre-historic man first felt the feeble current
+of intellectual curiosity amid his awe of the storm; it has still to
+grow almost infinitely before anything like a complete explanation
+even of external Nature is achieved.
+
+Suppose that, at some future day, all physical and mechanical laws
+should be found to be direct consequences of a single majestic law,
+just as all the motions of the planets are (but--are they?) the direct
+results of the single law of gravitation. Gravitation will, probably,
+soon be explained in terms of some remoter cause, but the reason of
+that single and ultimate law of the universe which we have imagined
+would still remain unknown. Human knowledge will always have limits,
+and beyond those limits there will always be room for mystery and
+wonder. A complete and exhaustive explanation of the world is
+inconceivable, so long as human powers and capacities remain at all as
+they now are.
+
+It is important to emphasize such truths, especially in a book
+addressed to the young. When a lad hears for the first time that an
+astronomer, by a simple pointing of his spectroscope, can determine
+with what velocity a star is approaching the earth, or receding from
+it, or when he hears that the very shape of the revolving masses of
+certain stars can be calculated from simple measures of the sort, he
+is apt to conclude that Science, which has made such astounding
+advances since the days of Galileo and Newton, must eventually reach a
+complete explanation of the entire universe. The conclusion is not
+unnatural, but it is not correct. There are limits beyond which
+Science, in this sense, cannot go. Its scope is limited. Beyond its
+limits there are problems that it cannot solve, mysteries that it
+cannot explain.
+
+At the present moment, for example, the nature of Force is unknown. A
+weight released from the hand drops to the earth. Exactly what is the
+nature of the force with which the earth attracts it? We do not know,
+but it so happens that it is more than likely that an explanation will
+be reached in our own day. Gravity will be explained in terms of some
+more general forces. The mystery will be pushed back another step, and
+yet another and another. But the progress is not indefinite. If all
+the mechanical actions of the entire universe were to be formulated as
+the results of a single law or cause, the cause of that cause would be
+still to seek, as has been said.
+
+We have every right to exult in the amazing achievements of Science;
+but we have not understood them until we realize that the universe of
+Science has strict limits, within which all its conquests must
+necessarily be confined. Humility, and not pride, is the final lesson
+of scientific work and study.
+
+       *       *       *       *       *
+
+The choice of the selections printed in this volume has been
+necessarily limited by many hampering conditions, that of mere space
+being one of the most harassing. Each of the chapters might readily be
+expanded into a volume. Volumes might be added on topics almost
+untouched here. It has been necessary to pass over almost without
+notice matters of surpassing interest and importance: Electricity and
+its wonderful and new applications; the new Biology, with its views
+upon such fundamental questions as the origins of life and death;
+modern Astronomy, with its far-reaching pronouncements upon the fate
+of universes. All these can only be touched lightly, if at all. It is
+the chief purpose of this volume to point the way towards the most
+modern and the greatest conclusions of Science, and to lay foundations
+upon which the reading of a life-time can be laid.
+
+[Illustration: Signature: Edward S. Holden]
+
+UNITED STATES MILITARY ACADEMY, WEST POINT, _January 1, 1902_.
+
+
+
+
+WONDERS OF EARTH, SEA, AND SKY
+
+
+
+
+WHAT THE EARTH'S CRUST IS MADE OF
+
+(FROM THE WORLD'S FOUNDATIONS.)
+
+BY AGNES GIBERNE.
+
+
+     "Stand still and consider the wondrous works of God."
+
+[Illustration]
+
+What is the earth made of--this round earth upon which we human beings
+live and move?
+
+A question more easily asked than answered, as regards a very large
+portion of it. For the earth is a huge ball nearly eight thousand
+miles in diameter, and we who dwell on the outside have no means of
+getting down more than a very little way below the surface. So it is
+quite impossible for us to speak positively as to the inside of the
+earth, and what it is made of. Some people believe the earth's inside
+to be hard and solid, while others believe it to be one enormous lake
+or furnace of fiery melted rock. But nobody really knows.
+
+This outside crust has been reckoned to be of many different
+thicknesses. One man will say it is ten miles thick, and another will
+rate it at four hundred miles. So far as regards man's knowledge of
+it, gained from mining, from boring, from examination of rocks, and
+from reasoning out all that may be learned from these observations, we
+shall allow an ample margin if we count the field of geology to extend
+some twenty miles downwards from the highest mountain-tops. Beyond
+this we find ourselves in a land of darkness and conjecture.
+
+Twenty miles is only one four-hundredth part of the earth's
+diameter--a mere thin shell over a massive globe. If the earth were
+brought down in size to an ordinary large school globe, a piece of
+rough brown paper covering it might well represent the thickness of
+this earth-crust, with which the science of geology has to do. And the
+whole of the globe, this earth of ours, is but one tiny planet in the
+great Solar System. And the centre of that Solar System, the blazing
+sun, though equal in size to more than a million earths, is yet
+himself but one star amid millions of twinkling stars, scattered
+broadcast through the universe. So it would seem at first sight that
+the field of geology is a small field compared with that of
+astronomy....
+
+With regard to the great bulk of the globe little can be said. Very
+probably it is formed through and through of the same materials as the
+crust. This we do not know. Neither can we tell, even if it be so
+formed, whether the said materials are solid and cold like the
+outside crust, or whether they are liquid with heat. The belief has
+been long and widely held that the whole inside of the earth is one
+vast lake or furnace of melted fiery-hot material, with only a thin
+cooled crust covering it. Some in the present day are inclined to
+question this, and hold rather that the earth is solid and cold
+throughout, though with large lakes of liquid fire here and there,
+under or in her crust, from which our volcanoes are fed....
+
+The materials of which the crust is made are many and various; yet,
+generally speaking, they may all be classed under one simple word, and
+that word is--_Rock_.
+
+It must be understood that, when we talk of rock in this geological
+sense, we do not only mean hard and solid stone, as in common
+conversation. Rock may be changed by heat into a liquid or "molten"
+state, as ice is changed by heat to water. Liquid rock may be changed
+by yet greater heat to vapor, as water is changed to steam, only we
+have in a common way no such heat at command as would be needed to
+effect this. Rock may be hard or soft. Rock maybe chalky, clayey, or
+sandy. Rock may be so close-grained that strong force is needed to
+break it; or it may be so porous--so full of tiny holes--that water
+will drain through it; or it may be crushed and crumbled into loose
+grains, among which you can pass your fingers.
+
+The cliffs above our beaches are rock; the sand upon our seashore is
+rock; the clay used in brick-making is rock; the limestone of the
+quarry is rock; the marble of which our mantel-pieces are made is
+rock. The soft sandstone of South Devon, and the hard granite of the
+north of Scotland, are alike rock. The pebbles in the road are rock;
+the very mould in our gardens is largely composed of crumbled rock. So
+the word in its geological sense is a word of wide meaning.
+
+Now the business of the geologist is to read the history of the past
+in these rocks of which the earth's crust is made. This may seem a
+singular thing to do, and I can assure you it is not an easy task.
+
+For, to begin with, the history itself is written in a strange
+language, a language which man is only just beginning to spell out and
+understand. And this is only half the difficulty with which we have to
+struggle.
+
+If a large and learned book were put before you and you were set to
+read it through, you would perhaps, have no insurmountable difficulty,
+with patience and perseverance, in mastering its meaning.
+
+But how if the book were first chopped up into pieces, if part of it
+were flung away out of reach, if part of it were crushed into a pulp,
+if the numbering of the pages were in many places lost, if the whole
+were mixed up in confusion, and if _then_ you were desired to sort,
+and arrange, and study the volume?
+
+Picture to yourself what sort of a task this would be, and you will
+have some idea of the labors of the patient geologist.
+
+Rocks may be divided into several kinds or classes. For the present
+moment it will be enough to consider the two grand divisions--_Stratified
+rocks_ and _Unstratified rocks_.
+
+Unstratified rocks are those which were once, at a time more or less
+distant, in a melted state from intense heat, and which have since
+cooled into a half _crystallized_ state; much the same as water, when
+growing colder, cools and crystallizes into ice. Strictly speaking,
+ice is rock, just as much as granite and sandstone are rock. Water
+itself is of the nature of rock, only as we commonly know it in the
+liquid state we do not commonly call it so.
+
+[Illustration: UNSTRATIFIED ROCK.--A VOLCANIC BLOCK.]
+
+"Crystallization" means those particular forms or shapes in which the
+particles of a liquid arrange themselves, as that liquid hardens into
+a solid--in other words, as it freezes. Granite, iron, marble, are
+frozen substances, just as truly as ice is a frozen substance; for
+with greater heat they would all become liquid like water. When a
+liquid freezes, there are always crystals formed, though these are not
+always visible without the help of a microscope. Also the crystals are
+of different shapes with different substances.
+
+If you examine the surface of a puddle or pond, when a thin covering
+of ice is beginning to form, you will be able to see plainly the
+delicate sharp needle-like forms of the ice crystals. Break a piece of
+ice, and you will find that it will not easily break just in any way
+that you may choose, but it will only split along the lines of these
+needle-like crystals. This particular mode of splitting in a
+crystallized rock is called the _cleavage_ of that rock.
+
+Crystallization may take place either slowly or rapidly, and either
+in the open air or far below ground. The lava from a volcano is an
+example of rock which has crystallized rapidly in the open air; and
+granite is an example of rock which has crystallized slowly
+underground beneath great pressure.
+
+Stratified rocks, on the contrary, which make up a very large part of
+the earth's crust, are not crystallized. Instead of having cooled from
+a liquid into a solid state, they have been slowly _built up_, bit by
+bit and grain upon grain, into their present form, through long ages
+of the world's history. The materials of which they are made were
+probably once, long, long ago, the crumblings from granite and other
+crystallized rocks, but they show now no signs of crystallization.
+
+
+[Illustration: SECTION OF STRATIFIED ROCKS.
+
+_a._ Conglomerate. _b._ Pebbly Sandstone, _c._ Thin-bedded Sandstone,
+_d._ Shelly Sandstone, _e._ Shale. _f._ Limestone.]
+
+They are called "stratified" because they are in themselves made up of
+distinct layers, and also because they lie thus one upon another in
+layers, or _strata_, just as the leaves of a book lie, or as the
+bricks of a house are placed.
+
+Throughout the greater part of Europe, of Asia, of Africa, of North
+and South America, of Australia, these rocks are to be found,
+stretching over hundreds of miles together, north, south, east, and
+west, extending up to the tops of some of the earth's highest
+mountains, reaching down deep into the earth's crust. In many parts if
+you could dig straight downwards through the earth for thousands of
+feet, you would come to layer after layer of these stratified rocks,
+one kind below another, some layers thick, some layers thin, here a
+stratum of gravel, there a stratum of sandstone, here a stratum of
+coal, there a stratum of clay.
+
+But how, when, where, did the building up of all these rock-layers
+take place?
+
+[Illustration: THE BEACH IN THE FOREGROUND IS A ROCKY SHELF, THE
+REMNANT OF THE CLIFF WHICH ONCE EXTENDED OUT TO THE ISLAND.]
+
+
+People are rather apt to think of land and water on the earth as if
+they were fixed in one changeless form,--as if every continent and
+every island were of exactly the same shape and size now that it
+always has been and always will be.
+
+Yet nothing can be further from the truth. The earth-crust is a scene
+of perpetual change, of perpetual struggle, of perpetual building up,
+of perpetual wearing away.
+
+The work may go on slowly, but it does go on. The sea is always
+fighting against the land, beating down her cliffs, eating into her
+shores, swallowing bit by bit of solid earth; and rain and frost and
+inland streams are always busily at work, helping the ocean in her
+work of destruction. Year by year and century by century it continues.
+Not a country in the world which is bordered by the open sea has
+precisely the same coast-line that it had one hundred years ago; not a
+land in the world but parts each century with masses of its material,
+washed piecemeal away into the ocean.
+
+Is this hard to believe? Look at the crumbling cliffs around old
+England's shores. See the effect upon the beach of one night's fierce
+storm. Mark the pathway on the cliff, how it seems to have crept so
+near the edge that here and there it is scarcely safe to tread; and
+very soon, as we know, it will become impassable. Just from a mere
+accident, of course,--the breaking away of some of the earth, loosened
+by rain and frost and wind. But this is an accident which happens
+daily in hundreds of places around the shores.
+
+Leaving the ocean, look now at this river in our neighborhood, and see
+the slight muddiness which seems to color its waters. What from? Only
+a little earth and sand carried off from the banks as it flowed,--very
+unimportant and small in quantity, doubtless, just at this moment and
+just at this spot. But what of that little going on week after week,
+and century after century, throughout the whole course of the river,
+and throughout the whole course of every river and rivulet in our
+whole country and in every other country. A vast amount of material
+must every year be thus torn from the land and given to the ocean. For
+the land's loss here is the ocean's gain.
+
+And, strange to say, we shall find that this same ocean, so busily
+engaged with the help of its tributary rivers in pulling down land, is
+no less busily engaged with their help in building it up.
+
+You have sometimes seen directions upon a vial of medicine to "shake"
+before taking the dose. When you have so shaken the bottle the clear
+liquid grows thick; and if you let it stand for awhile the thickness
+goes off, and a fine grain-like or dust-like substance settles down at
+the bottom--the settlement or _sediment_ of the medicine. The finer
+this sediment, the slower it is in settling. If you were to keep the
+liquid in gentle motion, the fine sediment would not settle down at
+the bottom. With coarser and heavier grains the motion would have to
+be quicker to keep them supported in the water.
+
+Now it is just the same thing with our rivers and streams. Running
+water can support and carry along sand and earth, which in still water
+would quickly sink to the bottom; and the more rapid the movement of
+the water, the greater is the weight it is able to bear.
+
+This is plainly to be seen in the case of a mountain torrent. As it
+foams fiercely through its rocky bed it bears along, not only mud and
+sand and gravel, but stones and even small rocks, grinding the latter
+roughly together till they are gradually worn away, first to rounded
+pebbles, then to sand, and finally to mud. The material thus swept
+away by a stream, ground fine, and carried out to sea--part being
+dropped by the way on the river-bed--is called _detritus_, which
+simply means _worn-out_ material.
+
+[Illustration: A MOUNTAIN TORRENT.]
+
+The tremendous carrying-power of a mountain torrent can scarcely be
+realized by those who have not observed it for themselves. I have seen
+a little mountain-stream swell in the course of a heavy thunderstorm
+to such a torrent, brown and turbid with earth torn from the
+mountainside, and sweeping resistlessly along in its career a shower
+of stones and rock-fragments. That which happens thus occasionally
+with many streams is more or less the work all the year round of many
+more.
+
+As the torrent grows less rapid, lower down in its course, it ceases
+to carry rocks and stones, though the grinding and wearing away of
+stones upon the rocky bed continues, and coarse gravel is borne still
+upon its waters. Presently the widening stream, flowing yet more
+calmly, drops upon its bed all such coarser gravel as is not worn away
+to fine earth, but still bears on the lighter grains of sand. Next the
+slackening speed makes even the sand too heavy a weight, and that in
+turn falls to line the river-bed, while the now broad and placid
+stream carries only the finer particles of mud suspended in its
+waters. Soon it reaches the ocean, and the flow being there checked by
+the incoming ocean-tide, even the mud can no longer be held up, and it
+also sinks slowly in the shallows near the shore, forming sometimes
+broad mud-banks dangerous to the mariner.
+
+This is the case only with smaller rivers. Where the stream is
+stronger, the mud-banks are often formed much farther out at sea; and
+more often still the river-detritus is carried away and shed over the
+ocean-bed, beyond the reach of our ken. The powerful rush of water in
+earth's greater streams bears enormous masses of sand and mud each
+year far out into the ocean, there dropping quietly the gravel, sand,
+and earth, layer upon layer at the bottom of the sea. Thus pulling
+down and building up go on ever side by side; and while land is the
+theatre oftentimes of decay and loss, ocean is the theatre oftentimes
+of renewal and gain.
+
+
+Did you notice the word "sediment" used a few pages back about the
+settlement at the bottom of a medicine-vial?
+
+There is a second name given to the Stratified Rocks, of which the
+earth's crust is so largely made up. They are called also _Sedimentary
+Rocks_.
+
+The reason is simply this. The Stratified Rocks of the present day
+were once upon a time made up out of the sediment stolen first from
+land and then allowed to settle down on the sea-bottom.
+
+Long, long ago, the rivers, the streams, the ocean, were at work, as
+they are now, carrying away rock and gravel, sand and earth. Then, as
+now, all this material, borne upon the rivers, washed to and fro by
+the ocean, settled down at the mouths of rivers or at the bottom of
+the sea, into a sediment, one layer forming over another, gradually
+built up through long ages. At first it was only a soft, loose, sandy
+or muddy sediment, such as you may see on the seashore, or in a
+mud-bank. But as the thickness of the sediment increased, the weight
+of the layers above gradually pressed the lower layers into firm hard
+rocks; and still, as the work of building went on, these layers were,
+in their turn, made solid by the increasing weight over them. Certain
+chemical changes had also a share in the transformation from soft mud
+to hard rock, which need not be here considered.
+
+All this has through thousands of years been going on. The land is
+perpetually crumbling away; and fresh land under the sea is being
+perpetually built up, from the very same materials which the sea and
+the rivers have so mercilessly stolen from continents and islands.
+This is the way, if geologists rightly judge, in which a very large
+part of the enormous formations of Stratified or Sedimentary Rocks
+have been made.
+
+[Illustration: VIEW IN A CANON.]
+
+So far is clear. But now we come to a difficulty.
+
+The Stratified Rocks, of which a very large part of the continents is
+made, appear to have been built up slowly, layer upon layer, out of
+the gravel, sand, and mud, washed away from the land and dropped on
+the shore of the ocean.
+
+[Illustration: SEA CLIFFS SHOWING A SERIES OF STRATIFIED ROCKS.]
+
+You may see these layers for yourself as you walk out into the
+country. Look at the first piece of bluff rock you come near, and
+observe the clear pencil-like markings of layer above layer--not often
+indeed lying _flat_, one over another, and this must be explained
+later, but however irregularly slanting, still plainly visible. You
+can examine these lines of stratification on the nearest cliff, the
+nearest quarry, the nearest bare headland, in your neighborhood.
+
+But how can this be? If all these stratified rocks are built on the
+floor of the ocean out of material taken _from_ the land, how can we
+by any possibility find such rocks _upon_ the land? In the beds of
+rivers we might indeed expect to see them, but surely nowhere else
+save under ocean waters.
+
+Yet find them we do. Through England, through the two great
+world-continents, they abound on every side. Thousands of miles in
+unbroken succession are composed of such rocks.
+
+Stand with me near the seashore, and let us look around. Those white
+chalk cliffs--they, at least, are not formed of sand or earth. True,
+and the lines of stratification are in them very indistinct, if seen
+at all; yet they too are built up of sediment of a different kind,
+dropping upon ocean's floor. See, however, in the rough sides of
+yonder bluff the markings spoken of, fine lines running alongside of
+one another, sometimes flat, sometimes bent or slanting, but always
+giving the impression of layer piled upon layer. Yet how can one for a
+moment suppose that the ocean-waters ever rose so high?
+
+Stay a moment. Look again at yonder white chalk cliff, and observe a
+little way below the top a singular band of shingles, squeezed into
+the cliff, as it were, with chalk below and earth above.
+
+That is believed to be an old sea-beach. Once upon a time the waters
+of the sea are supposed to have washed those shingles, as now they
+wash the shore near which we stand, and all the white cliff must have
+lain then beneath the ocean.
+
+Geologists were for a long while sorely puzzled to account for these
+old sea-beaches, found high up in the cliffs around our land in many
+different places.
+
+They had at first a theory that the sea must once, in far back ages,
+have been a great deal higher than it is now. But this explanation
+only brought about fresh difficulties. It is quite impossible that the
+level of the sea should be higher in one part of the world than in
+another. If the sea around England were then one or two hundred feet
+higher than it is now, it must have been one or two hundred feet
+higher in every part of the world where the ocean-waters have free
+flow. One is rather puzzled to know where all the water could have
+come from, for such a tremendous additional amount. Besides, in some
+places remains of sea-animals are found in mountain heights, as much
+as two or three thousand feet above the sea-level--as, for instance,
+in Corsica. This very much increases the difficulty of the above
+explanation.
+
+So another theory was started instead, and this is now generally
+supposed to be the true one. What if instead of the whole ocean having
+been higher, parts of the land were lower? England at one time, parts
+of Europe at another time, parts of Asia and America at other times,
+may have slowly sunk beneath the ocean, and after long remaining there
+have slowly risen again.
+
+This is by no means so wild a supposition as it may seem when first
+heard, and as it doubtless did seem when first proposed. For even in
+the present day these movements of the solid crust of our earth are
+going on. The coasts of Sweden and Finland have long been slowly and
+steadily rising out of the sea, so that the waves can no longer reach
+so high upon those shores as in years gone by they used to reach. In
+Greenland, on the contrary, land has long been slowly and steadily
+sinking, so that what used to be the shore now lies under the sea.
+Other such risings and sinkings might be mentioned, as also many more
+in connection with volcanoes and earthquakes, which are neither slow
+nor steady, but sudden and violent.
+
+So it becomes no impossible matter to believe that, in the course of
+ages past, all those wide reaches of our continents and islands, where
+sedimentary rocks are to be found, were each in turn, at one time or
+another, during long periods, beneath the rolling waters of the
+ocean....
+
+       *       *       *       *       *
+
+These built-up rocks are not only called "Stratified," and
+"Sedimentary." They have also the name of _Aqueous Rock_, from the
+Latin word _aqua, water_; because they are believed to have been
+formed by the action of the water.
+
+They have yet another and fourth title, which is, _Fossiliferous
+Rocks_.
+
+Fossils are the hardened remains of animals and vegetables found in
+rocks. They are rarely, if ever, seen in unstratified rocks; but many
+layers of stratified rocks abound in these remains. Whole skeletons as
+well as single bones, whole tree-trunks as well as single leaves, are
+found thus embedded in rock-layers, where in ages past the animal or
+plant died and found a grave. They exist by thousands in many parts of
+the world, varying in size from the huge skeleton of the elephant to
+the tiny shell of the microscopic animalcule.
+
+[Illustration: FOSSIL OF CARBONIFEROUS FERN.]
+
+Fossils differ greatly in kind. Sometimes the entire shell or bone is
+changed into stone, losing all its animal substance, but retaining its
+old outline and its natural markings. Sometimes the fossil is merely
+the hardened impress of the outside of a shell or leaf, which has
+dented its picture on soft clay, and has itself disappeared, while the
+soft clay has become rock, and the indented picture remains fixed
+through after-centuries. Sometimes the fossil is the cast of the
+inside of a shell; the said shell having been filled with soft mud,
+which has taken its exact shape and hardened, while the shell itself
+has vanished. The most complete description of fossil is the first of
+these three kinds. It is wonderfully shown sometimes in fossil wood,
+where all the tiny cells and delicate fibres remain distinctly marked
+as of old, only the whole woody substance has changed into hard stone.
+
+[Illustration: FOOTPRINTS FROM TRIASSIC SANDSTONE OF CONNECTICUT.]
+
+But although the fossil remains of quadrupeds and other land-animals
+are found in large quantities, their number is small compared with the
+enormous number of fossil sea-shells and sea-animals.
+
+[Illustration: FOSSIL FOOTPRINTS.]
+
+Land-animals can, as a rule, have been so preserved, only when they
+have been drowned in ponds or rivers, or mired in bogs and swamps, or
+overtaken by frost, or swept out to sea.
+
+Sea-animals, on the contrary, have been so preserved on land whenever
+that land has been under the sea; and this appears to have been the
+case, at one or another past age, with the greater part of our
+present continents. These fossil remains of sea-animals are
+discovered in all quarters of the world, not only on the seashore but
+also far inland, not only deep down underground but also high up on
+the tops of lofty mountains--a plain proof that over the summits of
+those mountains the ocean must once have rolled, and this not for a
+brief space only, but through long periods of time. And not on the
+mountain-summit only are these fossils known to abound, but sometimes
+in layer below layer of the mountain, from top to bottom, through
+thousands of feet of rock.
+
+[Illustration: FOSSIL SHELLS.]
+
+This may well seem puzzling at first sight. Fossils of sea-creatures
+on a mountain-top are startling enough; yet hardly so startling as the
+thought of fossils _inside_ that mountain. How could they have found
+their way thither?
+
+The difficulty soon vanishes, if once we clearly understand that all
+these thousands of feet of rock were built up slowly, layer after
+layer, when portions of the land lay deep under the sea. Thus _each
+separate layer_ of mud or sand or other material became in its turn
+the _top layer_, and was for the time the floor of the ocean, until
+further droppings of material out of the waters made a fresh layer,
+covering up the one below.
+
+While each layer was thus in succession the top layer of the building,
+and at the same time the floor of the ocean, animals lived and died
+in the ocean, and their remains sank to the bottom, resting upon the
+sediment floor. Thousands of such dead remains disappeared, crumbling
+into fine dust and mingling with the waters, but here and there one
+was caught captive by the half-liquid mud, and was quickly covered and
+preserved from decay. And still the building went on, and still layer
+after layer was placed, till many fossils lay deep down beneath the
+later-formed layers; and when at length, by slow or quick upheaval of
+the ground, this sea-bottom became a mountain, the little fossils were
+buried within the body of that mountain. So wondrously the matter
+appears to have come about.
+
+       *       *       *       *       *
+
+Another difficulty with respect to the stratified rocks has to be
+thought of. All these layers or deposits of gravel, sand, or earth, on
+the floor of the ocean, would naturally be horizontal--that is, would
+lie flat, one upon another. In places the ocean-floor might slant, or
+a crevice or valley or ridge might break the smoothness of the
+deposit. But though the layers might partake of the slant, though the
+valley might have to be filled, though the ridge might have to be
+surmounted, still the general tendency of the waves would be to level
+the dropping deposits into flat layers.
+
+Then how is it that when we examine the strata of rocks in our
+neighborhood, wherever that neighborhood may be, we do not find them
+so arranged? Here, it is true, the lines for a space are nearly
+horizontal, but there, a little way farther on, they are
+perpendicular; here they are bent, and there curved; here they are
+slanting, and there crushed and broken.
+
+This only bears out what has been already said about the Book of
+Geology. It _has_ been bent and disturbed, crushed and broken.
+
+Great powers have been at work in this crust of our earth. Continents
+have been raised, mountains have been upheaved, vast masses of rock
+have been scattered into fragments. Here or there we may find the
+layers arranged as they were first laid down; but far more often we
+discover signs of later disturbance, either slow or sudden, varying
+from a mere quiet tilting to a violent overturn.
+
+[Illustration: EXAMPLE OF DISTURBANCE OF THE EARTH'S LAYERS.]
+
+So the Book of Geology is a torn and disorganized volume, not easy to
+read.
+
+Yet, on the other hand, these very changes which have taken place are
+a help to the geologist.
+
+It may seem at first sight as if we should have an easier task, if the
+strata were all left lying just as they were first formed, in smooth
+level layers, one above another. But if it were so, we could know very
+little about the lower layers.
+
+We might indeed feel sure, as we do now, that the lowest layers were
+the oldest and the top layers the newest, and that any fossils found
+in the lower layers must belong to an age farther back than any
+fossils found in the upper layers.
+
+So much would be clear. And we might dig also and burrow a little way
+down, through a few different kinds of rock, where they were not too
+thick. But that would be all. There our powers would cease.
+
+Now how different. Through the heavings and tiltings of the earth's
+crust, the lower layers are often pushed quite up to the surface, so
+that we are able to examine them and their fossils without the least
+difficulty, and very often without digging underground at all.
+
+You must not suppose that the real order of the rocks is changed by
+these movements, for generally speaking it is not. The lower kinds are
+rarely if ever found placed _over_ the upper kinds; only the ends of
+them are seen peeping out above ground.
+
+It is as if you had a pile of copy-books lying flat one upon another,
+and were to put your finger under the lowest and push it up. All those
+above would be pushed up also, and perhaps they would slip a little
+way down, so that you would have a row of _edges_ showing side by
+side, at very much the same height. The arrangement of the copy-books
+would not be changed, for the lowest would still be the lowest in
+actual position; but a general tilting or upheaval would have taken
+place.
+
+Just such a tilting or upheaval has taken place again and again with
+the rocks forming our earth-crust. The edges of the lower rocks often
+show side by side with those of higher layers.
+
+But geologists know them apart. They are able to tell confidently
+whether such and such a rock, peeping out at the earth's surface,
+belongs really to a lower or a higher kind. For there is a certain
+sort of order followed in the arrangement of rock-layers all over the
+earth, and it is well known that some rocks are never found below some
+other rocks, that certain particular kinds are never placed above
+certain other kinds. Thus it follows that the fossils found in one
+description of rock, must be the fossils of animals which lived and
+died before the animals whose fossil remains are found in another
+neighboring rock, just because this last rock-layer was built upon the
+ocean-floor above and therefore later than the other.
+
+All this is part of the foreign language of geology--part of the
+piecing and arranging of the torn volume. Many mistakes are made; many
+blunders are possible; but the mistakes and blunders are being
+gradually corrected, and certain rules by which to read and understand
+are becoming more and more clear.
+
+It has been already said that unstratified rocks are those which have
+been at some period, whether lately or very long ago, in a liquid
+state from intense heat, and which have since cooled, either quickly
+or slowly, crystallizing as they cooled.
+
+Unstratified Rocks may be divided into two distinct classes.
+
+[Illustration: SECTION OF A LAVA BOMB.]
+
+First.--Volcanic Rocks, such as lava. These have been quickly cooled
+at the surface of the earth, or not far below it.
+
+Secondly.--Plutonic Rocks, such as granite. These have been slowly
+cooled deep down in the earth under heavy pressure.
+
+There is also a class of rocks, called metamorphic rocks, including
+some kinds of marble. These are, strictly speaking, crystalline rocks,
+and yet they are arranged in something like layers. The word
+"metamorphic" simply means "transformed." They are believed to have
+been once stratified rocks, perhaps containing often the remains of
+animals; but intense heat has later transformed them into crystalline
+rocks, and the animal remains have almost or quite vanished.
+
+[Illustration: LAVA-STREAM ON VESUVIUS.]
+
+Just as the different kinds of Stratified Rocks are often called
+Aqueous Rocks, or rocks formed by the action of water--so these
+different kinds of Unstratified Rocks are often called Igneous Rocks,
+or rocks formed by the action of fire--the name being taken from the
+Latin word for fire. The Metamorphic Rocks are sometimes described as
+"Aqueo-igneous," since both water and fire helped in the forming of
+them.
+
+It was at one time believed, as a matter of certainty, that granite
+and such rocks belonged to a period much farther back than the periods
+of the stratified rocks. That is to say, it was supposed that
+fire-action had come first and water-action second; that the fire-made
+rocks were all formed in very early ages, and that only water-made
+rocks still continued to be formed. So the name of Primary Rocks, or
+First Rocks, was given to the granites and other such rocks, and the
+name of Secondary Rocks to all water-built rocks; while those of the
+third class were called Transition Rocks, because they seemed to be a
+kind of link or stepping-stone in the change from the First to the
+Second Rocks.
+
+The chief reason for the general belief that fire-built rocks were
+older than water-built ones was, that the former are as a rule found
+to lie _lower_ than the latter. They form, as it were, the basement of
+the building, while the top-stories are made of water-built rocks.
+
+Many still believe that there is much truth in the thought. It is most
+probable, so far as we are able to judge, that the _first-formed_
+crust of rocks all over the earth was of cooled and crystallized
+material. As these rocks were crumbled and wasted by the ocean,
+materials would have been supplied for the building-up of rocks, layer
+upon layer.
+
+But this is conjecture. We cannot know with any certainty the course
+of events so far back in the past. And geologists are now able to
+state with tolerable confidence that, however old many of the granites
+may be, yet a large amount of the fire-built rocks are no older than
+the water-built rocks which lie over them.
+
+So by many geologists the names of Primary, Transition, and Secondary
+Formations are pretty well given up. It has been proposed to give
+instead to the crystallized rocks of all kinds the name of Underlying
+Rocks (Hypogene Rocks).
+
+But if they really do lie under, how can they possibly be of the same
+age? One would scarcely venture to suppose, in looking at a building,
+that the cellars had not been finished before the upper floors.
+
+True. In the first instance doubtless the cellars were first made,
+then the ground-floor, then the upper stories.
+
+When, however, the house was so built, alterations and improvements
+might be very widely carried on above and below. While one set of
+workmen were engaged in remodelling the roof, another set of workmen
+might be engaged in remodelling the kitchens and first floor, pulling
+down, propping up, and actually rebuilding parts of the lower walls.
+
+This is precisely what the two great fellow-workmen, Fire and Water,
+are ever doing in the crust of our earth. And if it be objected that
+such alterations too widely undertaken might result in slips, cracks,
+and slidings, of ceilings and walls in the upper stories, I can only
+say that such catastrophes _have_ been the result of underground
+alterations in that great building, the earth's crust....
+
+We see therefore clearly that, although the earliest fire-made rocks
+may very likely date farther back than the earliest water-made rocks,
+yet the making of the two kinds has gone on side by side, one below
+and the other above ground, through all ages up to the present moment.
+
+And just as in the present day water continues its busy work above
+ground of pulling down and building up, so also fire continues its
+busy work underground of melting rocks which afterwards cool into new
+forms, and also of shattering and upheaving parts of the earth-crust.
+
+For there can be no doubt that fiery heat does exist as a mighty power
+within our earth, though to what extent we are not able to say.
+
+These two fellow-workers in nature have different modes of working.
+One we can see on all sides, quietly progressing, demolishing land
+patiently bit by bit, building up land steadily grain by grain. The
+other, though more commonly hidden from sight, is fierce and
+tumultuous in character, and shows his power in occasional terrific
+outbursts.
+
+We can scarcely realize what the power is of the imprisoned fiery
+forces underground, though even we are not without some witness of
+their existence. From time to time even our firm land has been felt to
+tremble with a thrill from some far-off shock; and even in our country
+is seen the marvel of scalding water pouring unceasingly from deep
+underground....
+
+Think of the tremendous eruptions of Vesuvius, of Etna, of Hecla, of
+Mauna Loa. Think of whole towns crushed and buried, with their
+thousands of living inhabitants. Think of rivers of glowing lava
+streaming up from regions below ground, and pouring along the surface
+for a distance of forty, fifty, and even sixty miles, as in Iceland
+and Hawaii. Think of red-hot cinders flung from a volcano-crater to a
+height of ten thousand feet. Think of lakes of liquid fire in other
+craters, five hundred to a thousand feet across, huge cauldrons of
+boiling rock. Think of showers of ashes from the furnace below of yet
+another, borne so high aloft as to be carried seven hundred miles
+before they sank to earth again. Think of millions of red-hot stones
+flung out in one eruption of Vesuvius. Think of a mass of rock, one
+hundred cubic yards in size, hurled to a distance of eight miles or
+more out of the crater of Cotopaxi.
+
+[Illustration: HOT WELLS.]
+
+Think also of earthquake-shocks felt through twelve hundred miles of
+country. Think of fierce tremblings and heavings lasting in constant
+succession through days and weeks of terror. Think of hundreds of
+miles of land raised several feet in one great upheaval. Think of the
+earth opening in scores of wide-lipped cracks, to swallow men and
+beasts. Think of hot mud, boiling water, scalding stream, liquid rock,
+bursting from such cracks, or pouring from rents in a mountain-side.
+
+Truly these are signs of a state of things in or below the solid crust
+on which we live, that may make us doubt the absolute security of
+"Mother Earth."
+
+Different explanations have been put forward to explain this seemingly
+fiery state of things underground.
+
+Until lately the belief was widely held that our earth was one huge
+globe of liquid fire, with only a slender cooled crust covering her, a
+few miles in thickness.
+
+This view was supported by the fact that heat is found to increase as
+men descend into the earth. Measurements of such heat-increase have
+been taken, both in mines and in borings for wells. The usual rate is
+about one degree more of heat, of our common thermometer, for every
+fifty or sixty feet of descent. If this were steadily continued, water
+would boil at a depth of eight thousand feet below the surface; iron
+would melt at a depth of twenty-eight miles; while at a depth of forty
+or fifty miles no known substance upon earth could remain solid.
+
+The force of this proof is, however, weakened by the fact that the
+rate at which the heat increases differs very much in different
+places. Also it is now generally supposed that such a tremendous
+furnace of heat--a furnace nearly eight thousand miles in
+diameter--could not fail to break up and melt so slight a covering
+shell.
+
+Many believe, therefore, not that the whole interior of the earth is
+liquid with heat, but that enormous fire-seas or lakes of melted rock
+exist here and there, under or in the earth-crust. From these lakes
+the volcanoes would be fed, and they would be the cause of earthquakes
+and land-upheavals or land-sinkings. There are strong reasons for
+supposing that the earth was once a fiery liquid body, and that she
+has slowly cooled through long ages. Some hold that her centre
+probably grew solid first from tremendous pressure; that her crust
+afterwards became gradually cold; and that between the solid crust and
+the solid inside or "nucleus," a sea of melted rock long existed, the
+remains of which are still to be found in these tremendous fiery
+reservoirs.
+
+The idea accords well with the fact that large numbers of extinct or
+dead volcanoes are scattered through many parts of the earth. If the
+above explanation be the right one, doubtless the fire-seas in the
+crust extended once upon a time beneath such volcanoes, but have since
+died out or smouldered low in those parts.
+
+A somewhat curious calculation has been made, to illustrate the
+different modes of working of these two mighty powers--Fire and Water.
+
+The amount of land swept away each year in mud, and borne to the ocean
+by the River Ganges, was roughly reckoned, and also the amount of land
+believed to have been upheaved several feet in the great Chilian
+earthquake.
+
+It was found that the river, steadily working month by month, would
+require some four hundred years to carry to the sea the same weight of
+material, which in one tremendous effort was upheaved by the fiery
+underground forces.
+
+Yet we must not carry this distinction too far. Fire does not always
+work suddenly, or water slowly; witness the slow rising and sinking of
+land in parts of the earth, continuing through centuries; and witness
+also the effects of great floods and storms.
+
+The crust of the earth is made of rock. But what is rock made of?
+
+Certain leading divisions of rocks have been already considered:
+
+The Water-made Rocks;
+
+The Fire-made Rocks, both Plutonic and Volcanic;
+
+The Water-and-Fire-made Rocks.
+
+The first of these--Water-made Rocks--may be subdivided into three
+classes. These are,--
+
+I. _Flint Rocks_; II. _Clay Rocks_; III. _Lime Rocks_.
+
+This is not a book in which it would be wise to go closely into the
+mineral nature of rocks. Two or three leading thoughts may, however,
+be given.
+
+Does it not seem strange that the hard and solid rocks should be in
+great measure formed of the same substances which form the thin
+invisible air floating around us?
+
+Yet so it is. There is a certain gas called Oxygen Gas. Without that
+gas you could not live many minutes. Banish it from the room in which
+you are sitting, and in a few minutes you will die.
+
+This gas makes up nearly one-quarter by weight of the atmosphere round
+the whole earth.
+
+The same gas plays an important part in the ocean; for more than
+three-quarters of water is _oxygen_.
+
+It plays also an important part in rocks; for about half the material
+of the entire earth's crust is oxygen.
+
+Another chief material in rocks is _silicon_. This makes up
+one-quarter of the crust, leaving only one-quarter to be accounted
+for. Silicon mixed with oxygen makes silica or quartz. There are few
+rocks which have not a large amount of quartz in them. Common flint,
+sandstones, and the sand of our shores, are made of quartz, and
+therefore belong to the first class of Silicious or Flint Rocks.
+Granites and lavas are about one-half quartz. The beautiful stones,
+amethyst, agate, chalcedony, and jasper, are all different kinds of
+quartz.
+
+Another chief material in rocks is a white metal called _aluminium_.
+United to oxygen it becomes alumina, the chief substance in clay.
+Rocks of this kind--such as clays, and also the lovely blue gem,
+sapphire--are called Argillaceous Rocks, from the Latin word for clay,
+and belong to the second class. Such rocks keep fossils well.
+
+Another is _calcium_. United to oxygen and carbonic acid, it makes
+carbonate of lime, the chief substance in limestone; so all limestones
+belong to the third class of Calcareous or Lime Rocks.
+
+Other important materials may be mentioned, such as _magnesium,
+potassium, sodium, iron, carbon, sulphur, hydrogen, chlorine,
+nitrogen_. These, with many more, not so common, make up the remaining
+quarter of the earth-crust.
+
+Carbon plays as important a part in animal and vegetable life as
+silicon in rocks. Carbon is most commonly seen in three distinct
+forms--as charcoal, as black-lead, and as the pure brilliant diamond.
+Carbon united, in a particular proportion, to oxygen, forms carbonic
+acid; and carbonic acid united, in a particular proportion, to lime,
+forms limestone.
+
+_Hydrogen_ united to oxygen forms water. Each of these two gases is
+invisible alone, but when they meet and mingle they form a liquid.
+
+_Nitrogen_ united to oxygen and to a small quantity of carbonic acid
+gas forms our atmosphere.
+
+Rocks of pure flint, pure clay, or pure lime, are rarely or never met
+with. Most rocks are made up of several different substances melted
+together.
+
+       *       *       *       *       *
+
+In the fire-built rocks no remains of animals are found, though in
+water-built rocks they abound. Water-built rocks are sometimes divided
+into two classes--those which only contain occasional animal remains,
+and those which are more or less built up of the skeletons of animals.
+
+[Illustration: AMIBA PRINCEPS, ONE OF THE MANY ORDERS OF THE RHIZOPODA
+CLASS, MAGNIFIED ONE HUNDRED TIMES.]
+
+There are some exceedingly tiny creatures inhabiting the ocean, called
+Rhizopods. They live in minute shells, the largest of which may be
+almost the size of a grain of wheat, but by far the greater number are
+invisible as shells without a microscope, and merely show as fine
+dust. The rhizopods are of different shapes, sometimes round,
+sometimes spiral, sometimes having only one cell, sometimes having
+several cells. In the latter case a separate animal lives in each
+cell. The animal is of the very simplest as well as the smallest kind.
+He has not even a mouth or a stomach but can take in food at any part
+of his body.
+
+[Illustration: RHIZOPODS (MAGNIFIED).]
+
+These rhizopods live in the oceans in enormous numbers. Tens of
+millions are ever coming into existence, living out their tiny lives,
+dying, and sinking to the bottom.
+
+There upon the ocean-floor gather their remains, a heaped-up multitude
+of minute skeletons or shells, layer forming over layer.
+
+It was long suspected that the white chalk cliffs of England were
+built up in some such manner as this through past ages. And now at
+length proof has been found, in the shape of mud dredged up from the
+ocean-bottom--mud entirely composed of countless multitudes of these
+little shells, dropping there by myriads, and becoming slowly joined
+together in one mass.
+
+Just so, it is believed, were the white chalk cliffs built--gradually
+prepared on the ocean-floor, and then slowly or suddenly upheaved, so
+as to become a part of the dry land.
+
+Think what the enormous numbers must have been of tiny living
+creatures, out of whose shells the wide reaches of white chalk cliffs
+have been made. Chalk cliffs and chalk layers extend from Ireland,
+through England and France, as far as to the Crimea. In the south of
+Russia they are said to be six hundred feet thick. Yet one cubic inch
+of chalk is calculated to hold the remains of more than one million
+rhizopods. How many countless millions upon millions must have gone to
+the whole structure! How long must the work of building up have
+lasted!
+
+[Illustration: THREE POLYPS OF CORAL.]
+
+These little shells do not always drop softly and evenly to the
+ocean-floor, to become quietly part of a mass of shells. Sometimes,
+where the ocean is shallow enough for the waves to have power below,
+or where land currents can reach, they are washed about, and thrown
+one against another, and ground into fine powder; and the fine powder
+becomes in time, through different causes, solid rock.
+
+[Illustration: CORAL POLYP.]
+
+Limestone is made in another way also. In the warm waters of the South
+Pacific Ocean there are many islands, large and small, which have
+been formed in a wonderful manner by tiny living workers. The workers
+are soft jelly-like creatures, called polyps, who labor together in
+building up great walls and masses of coral.
+
+[Illustration: CORAL ISLAND.]
+
+[Illustration: YOUNG CORAL POLYP ATTACHED TO A ROCK AND EXPANDED.]
+
+They never carry on their work above the surface of the water, for in
+the air they would die. But the waves break the coral, and heap it up
+above high-water mark, and carry earth and seeds to drop there till at
+length a small low-lying island is formed.
+
+The waves not only heap up broken coral, but they grind the coral into
+fine powder, and from this powder limestone rock is made, just as it
+is from the powdered shells of rhizopods. The material used by the
+polyps in building the coral is chiefly lime, which they have the
+power of gathering out of the water, and the fine coral-powder,
+sinking to the bottom, makes large quantities of hard limestone. Soft
+chalk is rarely, if ever, found near the coral islands.
+
+[Illustration: 1. WHITE CORAL. 2. PORTION OF A BRANCH (MAGNIFIED).]
+
+Limestones are formed in the same manner from the grinding up of other
+sea-shells and fossils, various in kind; the powder becoming gradually
+united into solid rock.
+
+There is yet another way in which limestone is made, quite different
+from all these. Sometimes streams of water have a large quantity of
+lime in them; and these as they flow will drop layers of lime which
+harden into rock. Or a lime-laden spring, making its way through the
+roof of an underground cavern, will leave all kinds of fantastic
+arrangements of limestone wherever its waters can trickle and drip.
+Such a cavern is called a "stalactite cave."
+
+       *       *       *       *       *
+
+So there are different kinds of fossil rock-making. There may be rocks
+made of other materials, with fossil simply buried in them. There may
+be rocks made entirely of fossils, which have gathered in masses as
+they sank to the sea-bottom, and have there become simply and lightly
+joined together. There may be rocks made of the ground-up powder of
+fossils, pressed into a solid substance or united by some other
+substance.
+
+Rocks are also often formed of whole fossils, or stones, or shells,
+bound into one by some natural soft sticky cement, which has gathered
+round them and afterwards grown hard, like the cement which holds
+together the stones in a wall.
+
+The tiny rhizopods (meaning root foot) which have so large a share in
+chalk and limestone making, are among the smallest and simplest known
+kinds of animal life.
+
+There are also some very minute forms of vegetable life, which exist
+in equally vast numbers, called Diatoms. For a long while they were
+believed to be living animals, like the rhizopods. Scientific men are
+now, however, pretty well agreed that they really are only vegetables
+or plants.
+
+The diatoms have each one a tiny shell or shield, not made of lime
+like the rhizopod-shells, but of flint. Some think that common flint
+may be formed of these tiny shells.
+
+Again, there is a kind of rock called Mountain Meal, which is entirely
+made up of the remains of diatoms. Examined under the microscope,
+thousands of minute flint shields of various shapes are seen. This
+rock, or earth, is very abundant in many places, and is sometimes used
+as a polishing powder. In Bohemia there is a layer of it no less than
+fourteen feet thick. Yet so minute are the shells of which it is
+composed, that one square inch of rock is said to contain about four
+thousand millions of them. Each one of these millions is a separate
+distinct fossil....
+
+       *       *       *       *       *
+
+[Illustration: SUCCESSION OF BURIED COAL-GROWTHS AND ERECT
+TREE-STUMPS. SYDNEY, CAPE BRETON.
+
+_a._ Sandstone, _b._ Shales, _c._ Coal-seams, _d._ Bed containing
+Roots and Stumps _in situ_.]
+
+If you examine carefully a piece of coal, you will find, more or less
+clearly, markings like those which are seen in a piece of wood.
+Sometimes they are very distinct indeed. Coal abounds in impressions
+of leaves, ferns, and stems, and fossil remains of plants and
+tree-trunks are found in numbers in coal-seams.
+
+Coal is a vegetable substance. The wide coal-fields of Britain and
+other lands are the _fossil_ remains of vast forests.
+
+Long ages ago, as it seems, broad and luxuriant forests flourished
+over the earth. In many parts generation after generation of trees
+lived and died and decayed, leaving no trace of their existence,
+beyond a little layer of black mould, soon to be carried away by wind
+and water. Coal could only be formed where there were bogs and
+quagmires.
+
+But in bogs and quagmires, and in shallow lakes of low-lying lands,
+there were great gatherings of slowly-decaying vegetable remains,
+trees, plants, and ferns all mingling together. Then after a while the
+low lands would sink and the ocean pouring in would cover them with
+layers of protecting sand or mud; and sometimes the land would rise
+again, and fresh forests would spring into life, only to be in their
+turn overwhelmed anew, and covered by fresh sandy or earthy deposits.
+
+These buried forests lay through the ages following, slowly hardening
+into the black and shining coal, so useful now to man.
+
+The coal is found thus in thin or thick seams, with other rock-layers
+between, telling each its history of centuries long past. In one place
+no less than sixteen such beds of coal are found, one below another,
+each divided from the next above and the next underneath by beds of
+clay or sand or shale. The forests could not have grown in the sea,
+and the earth-layers could not have been formed on land, therefore
+many land-risings and sinkings must have taken place. Each bed
+probably tells the tale of a succession of forests....
+
+       *       *       *       *       *
+
+Before going on to a sketch of the early ages of the Earth's
+history--ages stretching back long long before the time of Adam--it is
+needful to think yet for a little longer about the manner in which
+that history is written, and the way in which it has to be read.
+
+For the record is one difficult to make out, and its style of
+expression is often dark and mysterious. There is scarcely any other
+volume in the great Book of Nature, which the student is so likely to
+misread as this one. It is very needful, therefore, to hold the
+conclusions of geologists with a light grasp, guarding each with a
+"perhaps" or a "may be." Many an imposing edifice has been built, in
+geology, upon a rickety foundation which has speedily given way.
+
+In all ages of the world's history up to the present day, rock-making
+has taken place--fire-made rocks being fashioned underground, and
+water-made rocks being fashioned above ground though under water.
+
+Also in all ages different kinds of rocks have been fashioned side by
+side--limestone in one part of the world, sandstone in another, chalk
+in another, clay in another, and so on. There have, it is true, been
+ages when one kind seems to have been the _chief_ kind--an age of
+limestone, or an age of chalk. But even then there were doubtless more
+rock-buildings going on, though not to so great an extent. On the
+other hand, there may have been ages during which no limestone was
+made, or no chalk, or no clay. As a general rule, however, the various
+sorts of rock-building have probably gone on together. This was not so
+well understood by early geologists as it is now.
+
+The difficulty is often great of disentangling the different strata,
+and saying which was earlier and which later formed.
+
+Still, by close and careful study of the rocks which compose the
+earth's crust, a certain kind of order is found to exist, more or less
+followed out in all parts of the world. _When_ each layer was formed
+in England or in America, the geologist cannot possibly say. He can,
+however, assert, in either place, that a certain mass of rock was
+formed before a certain other mass in that same place, even though
+the two may seem to lie side by side; for he knows that they were so
+placed only by upheaval, and that once upon a time the one lay beneath
+the other.
+
+The geologist can go further. He can often declare that a certain mass
+of rock in America and a certain mass of rock in England, quite
+different in kind, were probably built up at about the same time. How
+long ago that time was he would be rash to attempt to say; but that
+the two belong to the same age he has good reason for supposing.
+
+We find rocks piled upon rocks in a certain order, so that we may
+generally be pretty confident that the lower rocks were first made,
+and the upper rocks the latest built. Further than this, we find in
+all the said layers of water-built rocks signs of past life.
+
+As already stated, much of this life was ocean-life, though not all.
+
+Below the sea, as the rock-layers were being formed, bit by bit, of
+earth dropping from the ocean to the ocean's floor, sea-creatures
+lived out their lives and died by thousands, to sink to that same
+floor. Millions passed away, dissolving and leaving no trace behind;
+but thousands were preserved--shells often, animals sometimes.
+
+Nor was this all. For now and again some part of the sea-bottom was
+upheaved, slowly or quickly, till it became dry land. On this dry land
+animals lived again, and thousands of them, too, died, and their bones
+crumbled into dust. But here and there one was caught in bog or frost,
+and his remains were preserved till, through lapse of ages, they
+turned to stone.
+
+Yet again that land would sink, and over it fresh layers were formed
+by the ocean-waters, with fresh remains of sea-animals buried in with
+the layers of sand or lime; and once more the sea-bottom would rise,
+perhaps then to continue as dry land, until the day when man should
+discover and handle these hidden remains.
+
+Now note a remarkable fact as to these fossils, scattered far and wide
+through the layers of stratified rock.
+
+In the uppermost and latest built rocks the animals found are the
+same, in great measure, as those which now exist upon the earth.
+
+Leaving the uppermost rocks, and examining those which lie a little
+way below, we find a difference. Some are still the same, and others,
+if not quite the same, are very much like what we have now; but here
+and there a creature of a different form appears.
+
+Go deeper still, and the kinds of animals change further. Fewer and
+fewer resemble those which now range the earth; more and more belong
+to other species.
+
+Descend through layer after layer till we come to rocks built in
+earliest ages and not one fossil shall we find precisely the same as
+one animal living now.
+
+So not only are the rocks built in successive order, stratum after
+stratum belonging to age after age in the past, but fossil-remains
+also are found in successive order, kind after kind belonging to past
+age after age.
+
+Although in the first instance the succession of fossils was
+understood by means of the succession of rock-layers, yet in the
+second place the arrangement of rock-layers is made more clear by the
+means of these very fossils.
+
+A geologist, looking at the rocks in America, can say which there were
+first-formed, which second-formed, which third-formed. Also, looking
+at the rocks in England, he can say which there were first-formed,
+second-formed, third-formed. He would, however, find it very
+difficult, if not impossible, to say which among any of the American
+rocks was formed at about the same time as any particular one among
+the English rocks, were it not for the help afforded him by these
+fossils.
+
+Just as the regular succession of rock-strata has been gradually
+learned, so the regular succession of different fossils is becoming
+more and more understood. It is now known that some kinds of fossils
+are always found in the oldest rocks, and in them only; that some
+kinds are always found in the newest rocks, and in them only; that
+some fossils are rarely or never found lower than certain layers; that
+some fossils are rarely or never found higher than certain other
+layers.
+
+So this fossil arrangement is growing into quite a history of the
+past. And a geologist, looking at certain rocks, pushed up from
+underground, in England and in America, can say: "These are very
+different kinds of rocks, it is true, and it would be impossible to
+say how long the building up of the one might have taken place before
+or after the other. But I see that in both these rocks there are
+exactly the same kinds of fossil-remains, differing from those in the
+rocks above and below. I conclude therefore that the two rocks belong
+to about the same great age in the world's past history, when the
+same animals were living upon the earth."
+
+Observing and reasoning thus, geologists have drawn up a general plan
+or order of strata; and the whole of the vast masses of water-built
+rocks throughout the world have been arranged in a regular succession
+of classes, rising step by step from earliest ages up to the present
+time.
+
+[Illustration]
+
+
+
+
+AMERICA THE OLD WORLD
+
+(FROM GEOLOGICAL SKETCHES.)
+
+BY L. AGASSIZ.
+
+
+[Illustration]
+
+First-born among the Continents, though so much later in culture and
+civilization than some of more recent birth, America, so far as her
+physical history is concerned, has been falsely denominated the _New
+World_. Hers was the first dry land lifted out of the waters, hers the
+first shore washed by the ocean that enveloped all the earth beside;
+and while Europe was represented only by islands rising here and there
+above the sea, America already stretched an unbroken line of land from
+Nova Scotia to the Far West.
+
+In the present state of our knowledge, our conclusions respecting the
+beginning of the earth's history, the way in which it took form and
+shape as a distinct, separate planet, must, of course, be very vague
+and hypothetical. Yet the progress of science is so rapidly
+reconstructing the past that we may hope to solve even this problem;
+and to one who looks upon man's appearance upon the earth as the
+crowning work in a succession of creative acts, all of which have had
+relation to his coming in the end, it will not seem strange that he
+should at last be allowed to understand a history which was but the
+introduction to his own existence. It is my belief that not only the
+future, but the past also, is the inheritance of man, and that we
+shall yet conquer our lost birthright.
+
+Even now our knowledge carries us far enough to warrant the assertion
+that there was a time when our earth was in a state of igneous fusion,
+when no ocean bathed it and no atmosphere surrounded it, when no wind
+blew over it and no rain fell upon it, but an intense heat held all
+its materials in solution. In those days the rocks which are now the
+very bones and sinews of our mother Earth--her granites, her
+porphyries, her basalts, her syenites--were melted into a liquid mass.
+As I am writing for the unscientific reader, who may not be familiar
+with the facts through which these inferences have been reached, I
+will answer here a question which, were we talking together, he might
+naturally ask in a somewhat sceptical tone. How do you know that this
+state of things ever existed, and, supposing that the solid materials
+of which our earth consists were ever in a liquid condition, what
+right have you to infer that this condition was caused by the action
+of heat upon them? I answer, Because it is acting upon them still;
+because the earth we tread is but a thin crust floating on a liquid
+sea of molten materials; because the agencies that were at work then
+are at work now, and the present is the logical sequence of the past.
+From artesian wells, from mines, from geysers, from hot springs, a
+mass of facts has been collected, proving incontestably the heated
+condition of all substances at a certain depth below the earth's
+surface; and if we need more positive evidence, we have it in the
+fiery eruptions that even now bear fearful testimony to the molten
+ocean seething within the globe and forcing its way but from time to
+time. The modern progress of Geology has led us by successive and
+perfectly connected steps back to a time when what is now only an
+occasional and rare phenomenon was the normal condition of our earth;
+when the internal fires were enclosed by an envelope so thin that it
+opposed but little resistance to their frequent outbreak, and they
+constantly forced themselves through this crust, pouring out melted
+materials that subsequently cooled and consolidated on its surface. So
+constant were these eruptions, and so slight was the resistance they
+encountered, that some portions of the earlier rock-deposits are
+perforated with numerous chimneys, narrow tunnels as it were, bored by
+the liquid masses that poured out through them and greatly modified
+their first condition.
+
+[Illustration: IDEAL SECTION OF A VOLCANO IN ACTION.]
+
+The question at once suggests itself, How was even this thin crust
+formed? what should cause any solid envelope, however slight and filmy
+when compared to the whole bulk of the globe, to form upon the surface
+of such a liquid mass? At this point of the investigation the
+geologist must appeal to the astronomer; for in this vague and
+nebulous border-land, where the very rocks lose their outlines and
+flow into each other, not yet specialized into definite forms and
+substances,--there the two sciences meet. Astronomy shows us our
+planet thrown off from the central mass of which it once formed a
+part, to move henceforth in an independent orbit of its own. That
+orbit, it tells us, passed through celestial spaces cold enough to
+chill this heated globe, and of course to consolidate it externally.
+We know, from the action of similar causes on a smaller scale and on
+comparatively insignificant objects immediately about us, what must
+have been the effect of this cooling process upon the heated mass of
+the globe. All substances when heated occupy more space than they do
+when cold. Water, which expands when freezing, is the only exception
+to this rule. The first effect of cooling the surface of our planet
+must have been to solidify it, and thus to form a film or crust over
+it. That crust would shrink as the cooling process went on; in
+consequence of the shrinking, wrinkles and folds would arise upon it,
+and here and there, where the tension was too great, cracks and
+fissures would be produced. In proportion as the surface cooled, the
+masses within would be affected by the change of temperature
+outside of them, and would consolidate internally also, the crust
+gradually thickening by this process.
+
+[Illustration: A VOLCANO.]
+
+But there was another element without the globe, equally powerful in
+building it up. Fire and water wrought together in this work, if not
+always harmoniously, at least with equal force and persistency. I have
+said that there was a time when no atmosphere surrounded the earth;
+but one of the first results of the cooling of its crust must have
+been the formation of an atmosphere, with all the phenomena connected
+with it,--the rising of vapors, their condensation into clouds, the
+falling of rains, the gathering of waters upon its surface. Water is a
+very active agent of destruction, but it works over again the
+materials it pulls down or wears away, and builds them up anew in
+other forms. As soon as an ocean washed over the consolidated crust of
+the globe, it would begin to abrade the surfaces upon which it moved,
+gradually loosening and detaching materials, to deposit them again as
+sand or mud or pebbles at its bottom in successive layers, one above
+another. Thus, in analyzing the crust of the globe, we find at once
+two kinds of rocks, the respective work of fire and water: the first
+poured out from the furnaces within, and cooling, as one may see any
+mass of metal cool that is poured out from a smelting-furnace to-day,
+in solid crystalline masses, without any division into separate layers
+or leaves; and the latter in successive beds, one over another, the
+heavier materials below, the lighter above, or sometimes in alternate
+layers, as special causes may have determined successive deposits of
+lighter or heavier materials at some given spot.
+
+There were many well-fought battles between geologists before it was
+understood that these two elements had been equally active in building
+up the crust of the earth. The ground was hotly contested by the
+disciples of the two geological schools, one of which held that the
+solid envelope of the earth was exclusively due to the influence of
+fire, while the other insisted that it had been accumulated wholly
+under the agency of water. This difference of opinion grew up very
+naturally; for the great leaders of the two schools lived in different
+localities, and pursued their investigations over regions where the
+geological phenomena were of an entirely opposite character,--the one
+exhibiting the effect of volcanic eruptions, the other that of
+stratified deposits. It was the old story of the two knights on
+opposite sides of the shield, one swearing that it was made of gold,
+the other that it was made of silver; and almost killing each other
+before they discovered that it was made of both. So prone are men to
+hug their theories and shut their eyes to any antagonistic facts, that
+it is related of Werner, the great leader of the Aqueous school, that
+he was actually on his way to see a geological locality of especial
+interest, but, being told that it confirmed the views of his
+opponents, he turned round and went home again, refusing to see what
+might force him to change his opinions. If the rocks did not confirm
+his theory, so much the worse for the rocks,--he would none of them.
+At last it was found that the two great chemists, fire and water, had
+worked together in the vast laboratory of the globe, and since then
+scientific men have decided to work together also; and if they still
+have a passage at arms occasionally over some doubtful point, yet the
+results of their investigations are ever drawing them nearer to each
+other,--since men who study truth, when they reach their goal, must
+always meet at last on common ground.
+
+The rocks formed under the influence of heat are called, in geological
+language, the Igneous, or, as some naturalists have named them, the
+Plutonic rocks, alluding to their fiery origin, while the others have
+been called Aqueous or Neptunic rocks, in reference to their origin
+under the agency of water. A simpler term, however, quite as
+distinctive, and more descriptive of their structure, is that of the
+stratified and massive or unstratified rocks. We shall see hereafter
+how the relative position of these two classes of rocks and their
+action upon each other enable us to determine the chronology of the
+earth, to compare the age of her mountains, and, if we have no
+standard by which to estimate the positive duration of her continents,
+to say at least which was the first-born among them, and how their
+characteristic features have been successfully worked out. I am aware
+that many of these inferences, drawn from what is called "the
+geological record," must seem to be the work of the imagination. In a
+certain sense this is true,--for imagination, chastened by correct
+observation, is our best guide in the study of Nature. We are too apt
+to associate the exercise of this faculty with works of fiction, while
+it is in fact the keenest detective of truth.
+
+[Illustration: DIKES.]
+
+Besides the stratified and massive rocks, there is still a third set,
+produced by the contact of these two, and called, in consequence of
+the changes thus brought about, the Metamorphic rocks. The effect of
+heat upon clay is to bake it into slate; limestone under the influence
+of heat becomes quick-lime, or, if subjected afterwards to the action
+of water, it is changed to mortar; sand under the same agency is
+changed to a coarse kind of glass. Suppose, then, that a volcanic
+eruption takes place in a region of the earth's surface where
+successive layers of limestone, of clay, and of sandstone, have been
+previously deposited by the action of water. If such an eruption has
+force enough to break through these beds, the hot, melted masses will
+pour out through the rent, flow over its edges, and fill all the
+lesser cracks and fissures produced by such a disturbance. What will
+be the effect upon the stratified rocks? Wherever these liquid masses,
+melted by a heat more intense than can be produced by any artificial
+means, have flowed over them or cooled in immediate contact with them,
+the clays will be changed to slate, the limestone will have assumed a
+character more like marble, while the sandstone will be vitrified.
+This is exactly what has been found to be the case, wherever the
+stratified rocks have been penetrated by the melted masses from
+beneath. They have been themselves partially melted by the contact,
+and when they have cooled again, their stratification, though still
+perceptible, has been partly obliterated, and their substance changed.
+Such effects may often be traced in dikes, which are only the cracks
+in rocks filled by materials poured into them at some period of
+eruption when the melted masses within the earth were thrown out and
+flowed like water into any inequality or depression of the surface
+around. The walls enclosing such a dike are often found to be
+completely altered by contact with its burning contents, and to have
+assumed a character quite different from the rocks of which they make
+a part; while the mass itself which fills the fissure shows by the
+character of its crystallization that it has cooled more quickly on
+the outside, where it meets the walls, than at the centre.
+
+The first two great classes of rocks, the unstratified and stratified
+rocks, represent different epochs in the world's physical history: the
+former mark its revolutions, while the latter chronicle its periods of
+rest. All mountains and mountain-chains have been upheaved by great
+convulsions of the globe, which rent asunder the surface of the earth,
+destroyed the animals and plants living upon it at the time, and were
+then succeeded by long intervals of repose, when all things returned
+to their accustomed order, ocean and river deposited fresh beds in
+uninterrupted succession, the accumulation of materials went on as
+before, a new set of animals and plants were introduced, and a time of
+building up and renewing followed the time of destruction. These
+periods of revolution are naturally more difficult to decipher than
+the periods of rest; for they have so torn and shattered the beds they
+uplifted, disturbing them from their natural relations to each other,
+that it is not easy to reconstruct the parts and give them coherence
+and completeness again. But within the last half-century this work has
+been accomplished in many parts of the world with an amazing degree of
+accuracy, considering the disconnected character of the phenomena to
+be studied; and I think I shall be able to convince my readers that
+the modern results of geological investigation are perfectly sound
+logical inferences from well-established facts. In this, as in so many
+other things, we are but "children of a larger growth." The world is
+the geologist's great puzzle-box; he stands before it like the child
+to whom the separate pieces of his puzzle remain a mystery till he
+detects their relation and sees where they fit, and then his fragments
+grow at once into a connected picture beneath his hand....
+
+When geologists first turned their attention to the physical history
+of the earth, they saw at once certain great features which they took
+to be the skeleton and basis of the whole structure. They saw the
+great masses of granite forming the mountains and mountain-chains,
+with the stratified rocks resting against their slopes; and they
+assumed that granite was the first primary agent, and that all
+stratified rocks must be of a later formation. Although this involved
+a partial error, as we shall see hereafter when we trace the upheavals
+of granite even into comparatively modern periods, yet it held an
+important geological truth also; for, though granite formations are by
+no means limited to those early periods, they are nevertheless very
+characteristic of them, and are indeed the foundation-stones on which
+the physical history of the globe is built.
+
+Starting from this landmark, the earlier geologists divided the
+world's history into three periods. As the historian recognizes
+Ancient History, the Middle Ages, and Modern History as distinct
+phases in the growth of the human race, so they distinguished between
+what they called the Primary period, when, as they believed, no life
+stirred on the surface of the earth; the Secondary or middle period,
+when animals and plants were introduced, and the land began to assume
+continental proportions; and the Tertiary period, or comparatively
+modern geological times, when the physical features of the earth as
+well as its inhabitants were approaching more nearly to the present
+condition of things. But as their investigations proceeded, they found
+that every one of these great ages of the world's history was divided
+into numerous lesser epochs, each of which had been characterized by a
+peculiar set of animals and plants, and had been closed by some great
+physical convulsion, disturbing and displacing the materials
+accumulated during such a period of rest.
+
+The further study of these subordinate periods showed that what had
+been called Primary formations, namely, the volcanic or Plutonic rocks
+formerly believed to be confined to the first geological ages,
+belonged to all the periods, successive eruptions having taken place
+at all times, pouring up through the accumulated deposits, penetrating
+and injecting their cracks, fissures, and inequalities, as well as
+throwing out large masses on the surface. Up to our own day there has
+never been a period when such eruptions have not taken place, though
+they have been constantly diminishing in frequency and extent. In
+consequence of this discovery, that rocks of igneous character were by
+no means exclusively characteristic of the earliest times, they are
+now classified together upon very different grounds from those on
+which geologists first united them; though, as the name _Primary_ was
+long retained, we still find it applied to them, even in geological
+works of quite recent date. This defect of nomenclature is to be
+regretted, as likely to mislead the student, because it seems to refer
+to time; whereas it no longer signifies the age of the rocks, but
+simply their character. The name Plutonic or Massive rocks is,
+however, now almost universally substituted for that of Primary.
+
+A wide field of investigation still remains to be explored by the
+chemist and the geologist together, in the mineralogical character of
+the Plutonic rocks, which differs greatly in the different periods.
+The earlier eruptions seem to have been chiefly granitic, though this
+must not be understood in too wide a sense, since there are granite
+formations even as late as the Tertiary period; those of the middle
+periods were mostly porphyries and basalts; while in the more recent
+ones, lavas predominate. We have as yet no clew to the laws by which
+this distribution of volcanic elements in the formation of the earth
+is regulated; but there is found to be a difference in the crystals of
+the Plutonic rocks belonging to different ages, which, when fully
+understood may enable us to determine the age of any Plutonic rock by
+its mode of crystallization; so that the mineralogist will as readily
+tell you by its crystals whether a bit of stone of igneous origin
+belongs to this or that period of the world's history, as the
+palaeontologist will tell you by its fossils whether a piece of rock
+of aqueous origin belongs to the Silurian or Devonian or Carboniferous
+deposits.
+
+Although subsequent investigations have multiplied so extensively not
+only the number of geological periods, but also the successive
+creations that have characterized them, yet the first general division
+into three great eras was nevertheless founded upon a broad and true
+generalization. In the first stratified rocks in which any organic
+remains are found, the highest animals are fishes, and the highest
+plants are cryptogams; in the middle periods reptiles come in,
+accompanied by fern and moss forests; in later times quadrupeds are
+introduced, with a dicotyledonous vegetation. So closely does the
+march of animal and vegetable life keep pace with the material
+progress of the world, that we may well consider these three
+divisions, included under the first general classification of its
+physical history, as the three Ages of Nature; the more important
+epochs which subdivide them may be compared to so many great
+dynasties, while the lesser periods are the separate reigns contained
+therein. Of such epochs there are ten, well known to geologists; of
+the lesser periods about sixty are already distinguished, while many
+more loom up from the dim regions of the past, just discerned by the
+eye of science, though their history is not yet unravelled.
+
+Before proceeding further, I will enumerate the geological epochs in
+their succession, confining myself, however, to such as are perfectly
+well established, without alluding to those of which the limits are
+less definitely determined, and which are still subject to doubts and
+discussions among geologists. As I do not propose to make here any
+treatise of Geology, but simply to place before my readers some
+pictures of the old world, with the animals and plants that have
+inhabited it at various times, I shall avoid, as far as possible, all
+debatable ground, and confine myself to those parts of my subject
+which are best known, and can therefore be more clearly presented.
+
+[Illustration: FOSSIL SCORPION.--SILURIAN PERIOD.]
+
+First, we have the Azoic period, _devoid of life_, as its name
+signifies,--namely, the earliest stratified deposits upon the heated
+film forming the first solid surface of the earth, in which no trace
+of living thing has ever been found. Next comes the Silurian period,
+when the crust of the earth had thickened and cooled sufficiently to
+render the existence of animals and plants upon it possible, and when
+the atmospheric conditions necessary to their maintenance were already
+established. Many of the names given to these periods are by no means
+significant of their character, but are merely the result of accident:
+as, for instance, that of Silurian, given by Sir Roderick Murchison to
+this set of beds, because he first studied them in that part of Wales
+occupied by the ancient tribe of the Silures. The next period, the
+Devonian, was for a similar reason named after the country of
+Devonshire in England, where it was first investigated. Upon this
+follows the Carboniferous period, with the immense deposits of coal
+from which it derives its name. Then comes the Permian period, named,
+again, from local circumstances, the first investigation of its
+deposits having taken place in the province of Permia in Russia. Next
+in succession we have the Triassic period, so called from the trio of
+rocks, the red sandstone, Muschel Kalk (shell-limestone), and Keuper
+(clay), most frequently combined in its formations; the Jurassic, so
+amply illustrated in the chain of the Jura, where geologists first
+found the clew to its history; and the Cretaceous period, to which the
+chalk cliffs of England and all the extensive chalk deposits belong.
+Upon these follow the so-called Tertiary formations, divided into
+three periods, all of which have received most characteristic names in
+this epoch of the world's history we see the first approach to a
+condition of things resembling that now prevailing, and Sir Charles
+Lyell has most fitly named its three divisions, the Eocene, Miocene,
+and Pliocene. The termination of the three words is made from the
+Greek word _Kainos_, recent; while _Eos_ signifies dawn, _Meion_ less,
+and _Pleion_ more. Thus Eocene indicates the dawn of recent species,
+Pliocene their increase, while Miocene, the intermediate term, means
+less recent. Above these deposits comes what has been called in
+science the present period,--_the modern times_ of the geologist,--that
+period to which man himself belongs, and since the beginning of which,
+though its duration be counted by hundreds of thousands of years,
+there has been no alteration in the general configuration of the
+earth, consequently no important modification of its climatic
+conditions, and no change in the animals and plants inhabiting it.
+
+[Illustration: CRUSTACEA.--DEVONIAN PERIOD.]
+
+[Illustration: FISH OF THE DEVONIAN PERIOD.]
+
+[Illustration: FISH OF THE CARBONIFEROUS PERIOD.]
+
+[Illustration: FOSSIL VEGETATION OF CARBONIFEROUS PERIOD.]
+
+[Illustration: FISH OF THE PERMIAN PERIOD.]
+
+I have spoken of the first of these periods, the Azoic, as having
+been absolutely devoid of life, and I believe this statement to be
+strictly true; but I ought to add that there is a difference of
+opinion among geologists upon this point, many believing that the
+first surface of our globe may have been inhabited by living beings,
+but that all traces of their existence have been obliterated by the
+eruptions of melted materials, which not only altered the character of
+those earliest stratified rocks, but destroyed all the organic remains
+contained in them. It will be my object to show, not only that the
+absence of the climatic and atmospheric conditions essential to
+organic life, as we understand it, must have rendered the previous
+existence of any living beings impossible, but also that the
+completeness of the Animal Kingdom in those deposits where we first
+find organic remains, its intelligible and coherent connections with
+the successive creations of all geological times and with the animals
+now living, afford the strongest internal evidence that we have indeed
+found in the lower Silurian formations, immediately following the
+Azoic, the beginning of life upon earth. When a story seems to us
+complete and consistent from the beginning to the end, we shall not
+seek for a first chapter, even though the copy in which we have read
+it be so torn and defaced as to suggest the idea that some portion of
+it may have been lost. The unity of the work, as a whole, is an
+incontestable proof that we possess it in its original integrity. The
+validity of this argument will be recognized, perhaps, only by those
+naturalists to whom the Animal Kingdom has begun to appear as a
+connected whole. For those who do not see order in Nature it can have
+no value.
+
+[Illustration: FOSSILS OF TRIASSIC VEGETATION.]
+
+[Illustration: BIRD OF THE JURASSIC PERIOD.(The Oldest Bird.)]
+
+[Illustration: SKELETON OF BIRD OF THE CRETACEOUS PERIOD.]
+
+[Illustration: SKELETON OF ANIMAL OF THE EOCENE PERIOD.]
+
+For a table containing the geological periods in their succession, I
+would refer to any modern text-book of Geology, or to an article in
+the _Atlantic Monthly_ for March, 1862, upon "Methods of Study in
+Natural History," where they are given in connection with the order of
+introduction of animals upon earth.
+
+Were these sets of rocks found always in the regular sequence in which
+I have enumerated them, their relative age would be easily
+determined, for their superposition would tell the whole story: the
+lowest would, of course, be the oldest, and we might follow without
+difficulty the ascending series, till we reached the youngest and
+uppermost deposits. But their succession has been broken up by
+frequent and violent alterations in the configuration of the globe.
+Land and water have changed their level,--islands have been
+transformed to continents,--sea-bottoms have become dry land, and dry
+land has sunk to form sea-bottoms,--Alps and Himalayas, Pyrenees and
+Apennines, Alleghanies and Rocky Mountains, have had their stormy
+birthdays since many of these beds have been piled one above another,
+and there are but few spots on the earth's surface where any number of
+them may be found in their original order and natural position. When
+we remember that Europe, which lies before us on the map as a
+continent, was once an archipelago of islands,--that, where the
+Pyrenees raise their rocky barrier between France and Spain, the
+waters of the Mediterranean and Atlantic met,--that, where the British
+Channel flows, dry land united England and France, and Nature in those
+days made one country of the lands parted since by enmities deeper
+than the waters that run between,--when we remember, in short, all the
+fearful convulsions that have torn asunder the surface of the earth,
+as if her rocky record had indeed been written on paper, we shall find
+a new evidence of the intellectual unity which holds together the
+whole physical history of the globe in the fact that through all the
+storms of time the investigator is able to trace one unbroken thread
+of thought from the beginning to the present hour.
+
+[Illustration: SKELETON OF ANIMAL OF THE MIOCENE PERIOD.]
+
+[Illustration: SKELETON OF ANIMAL OF THE PLIOCENE PERIOD.]
+
+The tree is known by its fruits,--and the fruits of chance are
+incoherence, incompleteness, unsteadiness, the stammering utterance of
+blind, unreasoning force. A coherence that binds all the geological
+ages in one chain, a stability of purpose that completes in the beings
+born to-day an intention expressed in the first creatures that swam in
+the Silurian ocean or crept upon its shores, a steadfastness of
+thought, practically recognized by man, if not acknowledged by him,
+whenever he traces the intelligent connection between the facts of
+Nature and combines them into what he is pleased to call his system of
+Geology, or Zooelogy, or Botany,--these things are not the fruits of
+chance or of an unreasoning force, but the legitimate results of
+intellectual power. There is a singular lack of logic, as it seems to
+me, in the views of the materialistic naturalists. While they consider
+classification, or, in other words, their expression of the relations
+between animals or between physical facts of any kind, as the work of
+their intelligence, they believe the relations themselves to be the
+work of physical causes. The more direct inference surely is, that, if
+it requires an intelligent mind to recognize them, it must have
+required an intelligent mind to establish them. These relations
+existed before man was created; they have existed ever since the
+beginning of time; hence, what we call the classification of facts is
+not the work of his mind in any direct original sense, but the
+recognition of an intelligent action prior to his own existence.
+
+There is, perhaps, no part of the world, certainly none familiar to
+science, where the early geological periods can be studied with so
+much ease and precision as in the United States. Along their northern
+borders, between Canada and the United States, there runs the low line
+of hills known as the Laurentian Hills. Insignificant in height,
+nowhere rising more than fifteen hundred or two thousand feet above
+the level of the sea, these are nevertheless the first mountains that
+broke the uniform level of the earth's surface and lifted themselves
+above the waters. Their low stature, as compared with that of other
+more lofty mountain-ranges, is in accordance with an invariable rule,
+by which the relative age of mountains may be estimated. The oldest
+mountains are the lowest, while the younger and more recent ones tower
+above their elders, and are usually more torn and dislocated also.
+This is easily understood, when we remember that all mountains and
+mountain-chains are the result of upheavals, and that the violence of
+the outbreak must have been in proportion to the strength of the
+resistance. When the crust of the earth was so thin that the heated
+masses within easily broke through it, they were not thrown to so
+great a height, and formed comparatively low elevations, such as the
+Canadian hills or the mountains of Bretagne and Wales. But in later
+times, when young, vigorous giants, such as the Alps, the Himalayas,
+or, later still, the Rocky Mountains, forced their way out from their
+fiery prison-house, the crust of the earth was much thicker, and
+fearful indeed must have been the convulsions which attended their
+exit.
+
+[Illustration: A PHYSICAL MAP OF THE UNITED STATES.]
+
+The Laurentian Hills form, then, a granite range, stretching from
+Eastern Canada to the Upper Mississippi, and immediately along its
+base are gathered the Azoic deposits, the first stratified beds, in
+which the absence of life need not surprise us, since they were
+formed beneath a heated ocean. As well might we expect to find the
+remains of fish or shells or crabs at the bottom of geysers or of
+boiling springs, as on those early shores bathed by an ocean of which
+the heat must have been so intense. Although, from the condition in
+which we find it, this first granite range has evidently never been
+disturbed by any violent convulsion since its first upheaval, yet
+there has been a gradual rising of that part of the continent; for the
+Azoic beds do not lie horizontally along the base of the Laurentian
+Hills in the position in which they must originally have been
+deposited, but are lifted and rest against their slopes. They have
+been more or less dislocated in this process, and are greatly
+metamorphized by the intense heat to which they must have been
+exposed. Indeed, all the oldest stratified rocks have been baked by
+the prolonged action of heat.
+
+It may be asked how the materials for those first stratified deposits
+were provided. In later times, when an abundant and various soil
+covered the earth, when every river brought down to the ocean, not
+only its yearly tribute of mud or clay or lime, but the debris of
+animals and plants that lived and died in its waters or along its
+banks, when every lake and pond deposited at its bottom in successive
+layers the lighter or heavier materials floating in its waters and
+settling gradually beneath them, the process by which stratified
+materials are collected and gradually harden into rock is more easily
+understood. But when the solid surface of the earth was only just
+beginning to form, it would seem that the floating matter in the sea
+can hardly have been in sufficient quantity to form any extensive
+deposits. No doubt there was some abrasion even of that first crust;
+but the more abundant source of the earliest stratification is to be
+found in the submarine volcanoes that poured their liquid streams into
+the first ocean. At what rate these materials would be distributed and
+precipitated in regular strata it is impossible to determine; but that
+volcanic materials were so deposited in layers is evident from the
+relative position of the earliest rocks. I have already spoken of the
+innumerable chimneys perforating the Azoic beds, narrow outlets of
+Plutonic rock, protruding through the earliest strata. Not only are
+such funnels filled with the crystalline mass of granite that flowed
+through them in a liquid state, but it has often poured over their
+sides, mingling with the stratified beds around. In the present state
+of our knowledge, we can explain such appearances only by supposing
+that the heated materials within the earth's crust poured out
+frequently, meeting little resistance,--that they then scattered and
+were precipitated in the ocean around, settling in successive strata
+at its bottom,--that through such strata the heated masses within
+continued to pour again and again, forming for themselves the
+chimney-like outlets above mentioned.
+
+Such, then, was the earliest American land,--a long, narrow island,
+almost continental in its proportions, since it stretched from the
+eastern borders of Canada nearly to the point where now the base of
+the Rocky Mountains meets the plain of the Mississippi Valley. We may
+still walk along its ridge and know that we tread upon the ancient
+granite that first divided the waters into a northern and southern
+ocean; and if our imaginations will carry us so far, we may look down
+toward its base and fancy how the sea washed against this earliest
+shore of a lifeless world. This is no romance, but the bald, simple
+truth; for the fact that this granite band was lifted out of the
+waters so early in the history of the world, and has not since been
+submerged, has, of course, prevented any subsequent deposits from
+forming above it. And this is true of all the northern part of the
+United States. It has been lifted gradually, the beds deposited in one
+period being subsequently raised, and forming a shore along which
+those of the succeeding one collected, so that we have their whole
+sequence before us. In regions where all the geological deposits
+(Silurian, Devonian, carboniferous, permian, triassic, etc.) are piled
+one upon another, and we can get a glimpse of their internal relations
+only where some rent has laid them open, or where their ragged edges,
+worn away by the abrading action of external influences, expose to
+view their successive layers, it must, of course, be more difficult to
+follow their connection. For this reason the American continent offers
+facilities to the geologist denied to him in the so-called Old World,
+where the earlier deposits are comparatively hidden, and the broken
+character of the land, intersected by mountains in every direction,
+renders his investigation still more difficult. Of course, when I
+speak of the geological deposits as so completely unveiled to us here,
+I do not forget the sheet of drift which covers the continent from
+north to south, and which we shall discuss hereafter, when I reach
+that part of my subject. But the drift is only a superficial and
+recent addition to the soil, resting loosely above the other
+geological deposits, and arising, as we shall see, from very different
+causes.
+
+In this article I have intended to limit myself to a general sketch of
+the formation of the Laurentian Hills with the Azoic stratified beds
+resting against them. In the Silurian epoch following the Azoic we
+have the first beach on which any life stirred; it extended along the
+base of the Azoic beds, widening by its extensive deposits the narrow
+strip of land already upheaved. I propose ... to invite my readers to
+a stroll with me along that beach.
+
+With what interest do we look upon any relic of early human history!
+The monument that tells of a civilization whose hieroglyphic records
+we cannot even decipher, the slightest trace of a nation that vanished
+and left no sign of its life except the rough tools and utensils
+buried in the old site of its towns or villages, arouses our
+imagination and excites our curiosity. Men gaze with awe at the
+inscription on an ancient Egyptian or Assyrian stone; they hold with
+reverential touch the yellow parchment-roll whose dim, defaced
+characters record the meagre learning of a buried nationality; and the
+announcement, that for centuries the tropical forests of Central
+America have hidden within their tangled growth the ruined homes and
+temples of a past race, stirs the civilized world with a strange, deep
+wonder.
+
+To me it seems, that to look on the first land that was ever lifted
+above the waste of waters, to follow the shore where the earliest
+animals and plants were created when the thought of God first
+expressed itself in organic forms, to hold in one's hand a bit of
+stone from an old sea-beach, hardened into rock thousands of
+centuries ago, and studded with the beings that once crept upon its
+surface or were stranded there by some retreating wave, is even of
+deeper interest to men than the relies of their own race, for these
+things tell more directly of the thoughts and creative acts of God.
+
+Standing in the neighborhood of Whitehall, near Lake George, one may
+look along such a seashore, and see it stretching westward and sloping
+gently southward as far as the eye can reach. It must have had a very
+gradual slope, and the waters must have been very shallow; for at that
+time no great mountains had been uplifted, and deep oceans are always
+the concomitants of lofty heights. We do not, however, judge of this
+by inference merely; we have an evidence of the shallowness of the sea
+in those days in the character of the shells found in the Silurian
+deposits, which shows that they belonged in shoal waters.
+
+Indeed, the fossil remains of all times tell us almost as much of the
+physical condition of the world at different epochs as they do of its
+animal and vegetable population. When Robinson Crusoe first caught
+sight of the footprint on the sand, he saw in it more than the mere
+footprint, for it spoke to him of the presence of men on his desert
+island. We walk on the old geological shores, like Crusoe along his
+beach, and the footprints we find there tell us, too, more than we
+actually see in them. The crust of our earth is a great cemetery,
+where the rocks are tombstones on which the buried dead have written
+their own epitaphs. They tell us not only who they were and when and
+where they lived, but much also of the circumstances under which they
+lived. We ascertain the prevalence of certain physical conditions at
+special epochs by the presence of animals and plants whose existence
+and maintenance required such a state of things, more than by any
+positive knowledge respecting it. Where we find the remains of
+quadrupeds corresponding to our ruminating animals, we infer not only
+land, but grassy meadows also, and an extensive vegetation; where we
+find none but marine animals, we know the ocean must have covered the
+earth; the remains of large reptiles, representing, though in gigantic
+size, the half aquatic, half terrestrial reptiles of our own period,
+indicate to us the existence of spreading marshes still soaked by the
+retreating waters; while the traces of such animals as live now in
+sand and shoal waters, or in mud, speak to us of shelving sandy
+beaches and of mud-flats. The eye of the Trilobite tells us that the
+sun shone on the old beach where he lived; for there is nothing in
+nature without a purpose, and when so complicated an organ was made to
+receive the light, there must have been light to enter it. The immense
+vegetable deposits in the Carboniferous period announce the
+introduction of an extensive terrestrial vegetation; and the
+impressions left by the wood and leaves of the trees show that these
+first forests must have grown in a damp soil and a moist atmosphere.
+In short, all the remains of animals and plants hidden in the rocks
+have something to tell of the climatic conditions and the general
+circumstances under which they lived, and the study of fossils is to
+the naturalist a thermometer by which he reads the variations of
+temperature in past times, a plummet by which he sounds the depths of
+the ancient oceans,--a register, in fact, of all the important
+physical changes the earth has undergone.
+
+But although the animals of the early geological deposits indicate
+shallow seas by their similarity to our shoal-water animals, it must
+not be supposed that they are by any means the same. On the contrary,
+the old shells, crustacea, corals, etc., represent types which have
+existed in all times with the same essential structural elements, but
+under different specific forms in the several geological periods. And
+here it may not be amiss to say something of what are called by
+naturalists _representative types_.
+
+The statement that different sets of animals and plants have
+characterized the successive epochs is often understood as indicating
+a difference of another kind than that which distinguishes animals now
+living in different parts of the world. This is a mistake. There are
+so-called representative types all over the globe, united to each
+other by structural relations and separated by specific differences of
+the same kind as those that unite and separate animals of different
+geological periods. Take, for instance, mud-flats or sandy shores in
+the same latitudes of Europe and America; we find living on each,
+animals of the same structural character and of the same general
+appearance, but with certain specific differences, as of color, size,
+external appendages, etc. They represent each other on the two
+continents. The American wolves, foxes, bears, rabbits, are not the
+same as the European, but those of one continent are as true to their
+respective types as those of the other; under a somewhat different
+aspect they represent the same groups of animals. In certain
+latitudes, or under conditions of nearer proximity, these differences
+may be less marked. It is well known that there is a great monotony
+of type, not only among animals and plants, but in the human races
+also, throughout the Arctic regions; and some animals characteristic
+of the high North reappear under such identical forms in the
+neighborhood of the snow-fields in lofty mountains, that to trace the
+difference between the ptarmigans, rabbits, and other gnawing animals
+of the Alps, for instance, and those of the Arctics, is among the most
+difficult problems of modern science.
+
+And so it is also with the animated world of past ages; in similar
+deposits of sand, mud, or lime, in adjoining regions of the same
+geological age, identical remains of animals and plants may be found;
+while at greater distances, but under similar circumstances,
+representative species may occur. In very remote regions, however,
+whether the circumstances be similar or dissimilar, the general aspect
+of the organic world differs greatly, remoteness in space being thus
+in some measure an indication of the degree of affinity between
+different faunae. In deposits of different geological periods
+immediately following each other, we sometimes find remains of animals
+and plants so closely allied to those of earlier or later periods that
+at first sight the specific differences are hardly discernible. The
+difficulty of solving these questions, and of appreciating correctly
+the differences and similarities between such closely allied
+organisms, explains the antagonistic views of many naturalists
+respecting the range of existence of animals, during longer or shorter
+geological periods; and the superficial way in which discussions
+concerning the transition of species are carried on, is mainly owing
+to an ignorance of the conditions above alluded to. My own personal
+observation and experience in these matters have led me to the
+conviction that every geological period has had its own
+representatives, and that no single species has been repeated in
+successive ages.
+
+The laws regulating the geographical distribution of animals, and
+their combination into distinct zooelogical provinces called faunae,
+with definite limits, are very imperfectly understood as yet; but so
+closely are all things linked together from the beginning that I am
+convinced we shall never find the clew to their meaning till we carry
+on our investigations in the past and the present simultaneously. The
+same principle according to which animal and vegetable life is
+distributed over the surface of the earth now, prevailed in the
+earliest geological periods. The geological deposits of all times have
+had their characteristic faunae under various zones, their zooelogical
+provinces presenting special combinations of animal and vegetable life
+over certain regions, and their representative types reproducing in
+different countries, but under similar latitudes, the same groups with
+specific differences.
+
+Of course, the nearer we approach the beginning of organic life, the
+less marked do we find the differences to be, and for a very obvious
+reason. The inequalities of the earth's surface, her mountain-barriers
+protecting whole continents from the Arctic winds, her open plains
+exposing others to the full force of the polar blasts, her snug
+valleys and her lofty heights, her tablelands and rolling prairies,
+her river-systems and her dry deserts, her cold ocean-currents pouring
+down from the high North on some of her shores, while warm ones from
+tropical seas carry their softer influence to others,--in short, all
+the contrasts in the external configuration of the globe, with the
+physical conditions attendant upon them, are naturally accompanied by
+a corresponding variety in animal and vegetable life.
+
+But in the Silurian age, when there were no elevations higher than the
+Canadian hills, when water covered the face of the earth, with the
+exception of a few isolated portions lifted above the almost universal
+ocean, how monotonous must have been the conditions of life! And what
+should we expect to find on those first shores? If we are walking on a
+sea-beach to-day, we do not look for animals that haunt the forests or
+roam over the open plains, or for those that live in sheltered valleys
+or in inland regions or on mountain-heights. We look for Shells, for
+Mussels and Barnacles, for Crabs, for Shrimps, for Marine Worms, for
+Star-Fishes and Sea-Urchins, and we may find here and there a fish
+stranded on the sand or tangled in the seaweed.
+
+[Illustration]
+
+
+
+
+SOME RECORDS OF THE ROCKS
+
+(FROM A FIRST BOOK IN GEOLOGY.)
+
+BY N.S. SHALER, S.D.[1]
+
+[Footnote 1: Copyright, 1884, by N.S. Shaler.]
+
+[Illustration]
+
+The geologist cannot find his way back in the record of the great
+stone book, to the far-off day when life began. The various changes
+that come over rocks from the action of heat, of water, and of
+pressure, have slowly modified these ancient beds, so that they no
+longer preserve the frames of the animals that were buried in them.
+
+These old rocks, which are so changed that we cannot any longer make
+sure that any animals lived in them, are called the "archaean," which
+is Greek for ancient. They were probably mud and sand and limestone
+when first made, but they have been changed to mica schists, gneiss,
+granite, marble, and other crystalline rocks. When any rock becomes
+crystalline, the fossils dissolve and disappear, as coins lose their
+stamp and form when they are melted in the jeweller's gold-pot.
+
+These ancient rocks that lie deepest in the earth are very thick, and
+must have taken a great time in building; great continents must have
+been worn down by rain and waves in order to supply the waste out of
+which they were made. It is tolerably certain that they took as much
+time during their making as has been required for all the other times
+since they were formed. During the vast ages of this archaean the life
+of our earth began to be. We first find many certain evidences of life
+in the rocks which lie on top of the archaean rock, and are known as
+the Cambriani and Silurian periods. There we have creatures akin to
+our corals and crabs and worms, and others that are the distant
+kindred of the cuttle-fishes and of our lamp-shells. There were no
+backboned animals, that is to say, no land mammals, reptiles, or
+fishes at this stage of the earth's history. It is not likely that
+there was any land life except of plants and those forms like the
+lowest ferns, and probably mosses. Nor is it likely that there were
+any large continents as at the present time, but rather a host of
+islands lying where the great lands now are, the budding tops of the
+continents just appearing above the sea.
+
+Although the life of this time was far simpler than at the present
+day, it had about as great variety as we would find on our present
+sea-floors. There were as many different species living at the same
+time on a given surface.
+
+The Cambrian and Silurian time--the time before the coming of the
+fishes--must have endured for many million years without any great
+change in the world. Hosts of species lived and died; half a dozen
+times or more the life of the earth was greatly changed. New species
+came much like those that had gone before, and only a little gain here
+and there was perceptible at any time. Still, at the end of the
+Silurian, the life of the world had climbed some steps higher in
+structure and in intelligence.
+
+[Illustration: FIG. 1. NORTH AMERICA IN CAMBRIAN TIME.]
+
+The next set of periods is known as the Devonian. It is marked by the
+rapid extension of the fishes; for, although the fishes began in the
+uppermost Silurian, they first became abundant in this time. These,
+the first strong-jawed tyrants of the sea, came all at once, like a
+rush of the old Norman pirates into the peaceful seas of Great
+Britain. They made a lively time among the sluggish beings of that
+olden sea. Creatures that were able to meet feebler enemies were swept
+away or compelled to undergo great changes, and all the life of the
+oceans seems to have a spur given to it by these quicker-formed and
+quicker-willed animals. In this Devonian section of our rocks we have
+proofs that the lands were extensively covered with forests of low
+fern trees, and we find the first trace of air-breathing animals in
+certain insects akin to our dragon-flies. In this stage of the earth's
+history the fishes grew constantly more plentiful, and the seas had a
+great abundance of corals and crinoids. Except for the fishes, there
+were no very great changes in the character of the life from that
+which existed in the earlier time of the Cambrian and Silurian. The
+animals are constantly changing, but the general nature of the life
+remains the same as in the earlier time.
+
+[Illustration: FIG. 2. RANICEPS LYELLI--COAL TIME SALAMANDER.]
+
+In the Carboniferous or coal-bearing age, we have the second great
+change in the character of the life on the earth. Of the earlier
+times, we have preserved only the rocks formed in the seas. But rarely
+do we find any trace of the land life or even of the life that lived
+along the shores. In this Carboniferous time, however, we have very
+extensive sheets of rocks which were formed in swamps in the way shown
+in the earlier part of this book. They constitute our coal-beds,
+which, though much worn away by rain and sea, still cover a large part
+of the land surface. These beds of coal grew in the air, and, although
+the swamps where they were formed had very little animal life in them,
+we find some fossils which tell us that the life of the land was
+making great progress; there are new insects, including beetles,
+cockroaches, spiders, and scorpions, and, what is far more important,
+there are some air-breathing, back-boned animals, akin to the
+salamanders and water-dogs of the present day. These were nearly as
+large as alligators, and of much the same shape, but they were
+probably born from the egg in the shape of tadpoles and lived for a
+time in the water as our young frogs, toads, and salamanders do. This
+is the first step upwards from the fishes to land vertebrates; and we
+may well be interested in it, for it makes one most important advance
+in creatures through whose lives our own existence became possible.
+Still, these ancient woods of the coal period must have had little of
+the life we now associate with the forests; there were still no birds,
+no serpents, no true lizards, no suck-giving animals, no flowers, and
+no fruits. These coal-period forests were sombre wastes of shade, with
+no sound save those of the wind, the thunder, and the volcano, or of
+the running streams and the waves on the shores.
+
+In the seas of the Carboniferous time, we notice that the ancient life
+of the earth is passing away. Many creatures, such as the trilobites,
+die out, and many other forms such as the crinoids or sea lilies
+become fewer in kind and of less importance. These marks of decay in
+the marine life continue into the beds just after the Carboniferous,
+known as the Permian, which are really the last stages of the
+coal-bearing period.
+
+When with the changing time we pass to the beds known as the Triassic,
+which were made just after the close of the Carboniferous time, we
+find the earth undergoing swift changes in its life. The moist climate
+and low lands that caused the swamps to grow so rapidly have ceased to
+be, and in their place we appear to have warm, dry air, and higher
+lands.
+
+On these lands of the Triassic time the air-breathing life made very
+rapid advances. The plants are seen to undergo considerable changes.
+The ferns no longer make up all the forests, but trees more like the
+pines began to abound, and insects became more plentiful and more
+varied.
+
+[Illustration: FIG. 3. CYCAS CIRCINALIS, AKIN TO HIGHEST PLANTS OF
+COAL TIME.]
+
+Hitherto the only land back-boned animal was akin to our salamanders.
+Now we have true lizards in abundance, many of them of large size.
+Some of them were probably plant-eaters, but most were flesh-eaters;
+some seem to have been tenants of the early swamps, and some dwelt in
+the forests.
+
+The creatures related to the salamanders have increased in the variety
+of their forms to a wonderful extent. We know them best by the tracks
+which they have left on the mud stones formed on the borders of lakes
+or the edge of the sea. In some places these footprints are found in
+amazing numbers and perfection. The best place for them is in the
+Connecticut Valley, near Turner's Falls, Mass. At this point the red
+sandstone and shale beds, which are composed of thin layers having a
+total thickness of several hundred feet, are often stamped over by
+these footprints like the mud of a barnyard. From the little we can
+determine from these footprints, the creatures seem to have been
+somewhat related to our frogs, but they generally had tails, and,
+though provided with four legs, were in the habit of walking on the
+hind ones alone like the kangaroo. A few of these tracks are shown in
+the figure on this page.
+
+[Illustration: FIG. 4. FOOT-PRINTS, CONNECTICUT SANDSTONES.]
+
+These strange creatures were of many different species. Some of them
+must have been six or seven feet high, for their steps are as much as
+three feet apart, and seem to imply a creature weighing several
+hundred pounds. Others were not bigger than robins. Strangely enough,
+we have never found their bones nor the creatures on which they fed,
+and but for the formation of a little patch of rocks here and there we
+should not have had even these footprints to prove to us that such
+creatures had lived in the Connecticut Valley in this far-off time.
+
+[Illustration: FIG. 5. FOOT-PRINT, TURNER'S FALLS.]
+
+But these wonderful forms are less interesting than two or three
+little fossil jaw-bones that prove to us that in this Triassic time
+the earth now bore another animal more akin to ourselves, in the shape
+of a little creature that gave suck to its young. Once more life takes
+a long upward step in this little opossum-like animal, perhaps the
+first creature whose young was born alive. These little creatures
+called Microlestes or Dromatherium, of which only one or two different
+but related species have been found in England and in North Carolina,
+appear to have been insect-eaters of about the size and shape of the
+Australian creature shown in Fig. 7. So far we know it in but few
+specimens,--altogether only an ounce or two of bones,--but they are
+very precious monuments of the past.
+
+[Illustration: FIG. 6. DROMATHERIUM SYLVESTRE AND TEETH OF MICROLESTES
+ANTIQUUS.]
+
+In this Triassic time the climate appears to have been rather dry, for
+in it we have many extensive deposits of salt formed by the
+evaporation of closed lakes, of seas, such as are now forming on the
+bottom of the Dead Sea, and the Great Salt Lake of Utah, and a hundred
+or more other similar basins of the present day.
+
+[Illustration: FIG. 7. MYRMECOBIUS.]
+
+In the sea animals of this time we find many changes. Already some of
+the giant lizard-like animals, which first took shape on the land, are
+becoming swimming-animals. They changed their feet to paddles, which,
+with the help of a flattened tail, force them through the water.
+
+The fishes on which these great swimming lizards preyed are more like
+the fishes of our present day than they were before. The trilobites
+are gone, and of the crinoids only a remnant is left. Most of the
+corals of the earlier days have disappeared, but the mollusks have not
+changed more than they did at several different times in the earliest
+stages of the earth's history.
+
+[Illustration: FIG. 8. ICHTHYOSAURUS AND PLESIOSAURUS.]
+
+After the Trias comes a long succession of ages in which the life of
+the world is steadily advancing to higher and higher planes; but for a
+long time there is no such startling change as that which came in the
+passage from the coal series of rocks to the Trias. This long set of
+periods is known to geologists as the age of reptiles. It is well
+named, for the kindred of the lizards then had the control of the
+land. There were then none of our large fish to dispute their control,
+so they shaped themselves to suit all the occupations that could give
+them a chance for a living. Some remained beasts of prey like our
+alligators, but grew to larger size; some took to eating the plants,
+and came to walk on their four legs as our ordinary beasts do, no
+longer dragging themselves on their bellies as do the lizard and
+alligator, their lower kindred. Others became flying creatures like
+our bats, only vastly larger, often with a spread of wing of fifteen
+or twenty feet. Yet others, even as strangely shaped, dwelt with the
+sharks in the sea.
+
+[Illustration: FIG. 9. REPTILES OF JURASSIC PERIOD.]
+
+In this time of the earth's history we have the first bird-like forms.
+They were feathered creatures, with bills carrying true teeth, and
+with strong wings; but they were reptiles in many features, having
+long, pointed tails such as none of our existing birds have. They show
+us that the birds are the descendants of reptiles, coming off from
+them as a branch does from the parent tree. The tortoises began in
+this series of rocks. At first they are marine or swimming forms, the
+box-turtles coming later. Here too begin many of the higher insects.
+Creatures like moths and bees appear, and the forests are enlivened
+with all the important kinds of insects, though the species were very
+different from those now living.
+
+In the age of reptiles the plants have made a considerable advance.
+Palms are plenty; forms akin to our pines and firs abound, and the old
+flowerless group of ferns begins to shrink in size, and no longer
+spreads its feathery foliage over all the land as before. Still there
+were none of our common broad-leaved trees; the world had not yet
+known the oaks, birches, maples, or any of our hard-wood trees that
+lose their leaves in autumn; nor were the flowering plants, those with
+gay blossoms, yet on the earth. The woods and fields were doubtless
+fresh and green, but they wanted the grace of blossoms, plants, and
+singing-birds. None of the animals could have had the social qualities
+or the finer instincts that are so common among animals of the present
+day. There were probably no social animals like our ants and bees, no
+merry singing creatures; probably no forms that went in herds. Life
+was a dull round of uncared-for birth, cruel self-seeking, and of
+death. The animals at best were clumsy, poorly-endowed creatures, with
+hardly more intelligence than our alligators.
+
+The little thread of higher life begun in the Microlestes and
+Dromatherium, the little insect-eating mammals of the forest, is
+visible all through this time. It held in its warm blood the powers of
+the time to come, but it was an insignificant thing among the mighty
+cold-blooded reptiles of these ancient lands. There are several
+species of them, but they are all small, and have no chance to make
+headway against the older masters of the earth.
+
+The Jurassic or first part of the reptilian time shades insensibly
+into the second part, called the Cretaceous, which immediately follows
+it. During this period the lands were undergoing perpetual changes;
+rather deep seas came to cover much of the land surfaces, and there is
+some reason to believe that the climate of the earth became much
+colder than it had been, at least in those regions where the great
+reptiles had flourished. It may be that it is due to a colder climate
+that we owe the rapid passing away of this gigantic reptilian life of
+the previous age. The reptiles, being cold-blooded, cannot stand even
+a moderate winter cold, save when they are so small that they can
+crawl deep into crevices in the rocks to sleep the winter away,
+guarded from the cold by the warmth of the earth. At any rate these
+gigantic animals rapidly ceased to be, so that by the middle of the
+Cretaceous period they were almost all gone, except those that
+inhabited the sea; and at the end of this time they had shrunk to
+lizards in size. The birds continue to increase and to become more
+like those of our day; their tails shrink away, their long bills lose
+their teeth; they are mostly water-birds of large size, and there are
+none of our songsters yet; still they are for the first time perfect
+birds, and no longer half-lizard in their nature.
+
+The greatest change in the plants is found in the coming of the
+broad-leaved trees belonging to the families of our oaks, maples, etc.
+Now for the first time our woods take on their aspect of to-day; pines
+and other cone-bearers mingle with the more varied foliage of
+nut-bearing or large-seeded trees. Curiously enough, we lose sight of
+the little mammals of the earlier time. This is probably because there
+is very little in the way of land animals of this period preserved to
+us. There are hardly any mines or quarries in the beds of this age to
+bring these fossils to light. In the most of the other rocks there is
+more to tempt man to explore them for coal ores or building stones.
+
+In passing from the Cretaceous to the Tertiary, we enter upon the
+threshold of our modern world. We leave behind all the great wonders
+of the old world, the gigantic reptiles, the forests of tree ferns,
+the seas full of ammonites and belemnites, and come among the no less
+wonderful but more familiar modern forms. We come at once into lands
+and seas where the back-boned animals are the ruling beings. The
+reptiles have shrunk to a few low forms,--the small lizards, the
+crocodiles and alligators, the tortoises and turtles, and, as if to
+mark more clearly the banishment of this group from their old empire,
+the serpents, which are peculiarly degraded forms of reptiles which
+have lost the legs they once had, came to be the commonest reptiles of
+the earth.
+
+The first mammals that have no pouches now appear. In earlier times,
+the suck-giving animals all belonged to the group that contains our
+opossums, kangaroos, etc. These creatures are much lower and feebler
+than the mammals that have no pouches. Although they have probably
+been on the earth two or three times as long as the higher mammals,
+they have never attained any eminent success whatever; they cannot
+endure cold climates; none of them are fitted for swimming as are the
+seals and whales, or for flying as the bats, or for burrowing as the
+moles; they are dull, weak things, which are not able to contend with
+their stronger, better-organized, higher kindred. They seem not only
+weak, but unable to fit themselves to many different kinds of
+existence.
+
+In the lower part of the Tertiary rocks, we find at once a great
+variety of large beasts that gave suck to their young. It is likely
+that these creatures had come into existence in a somewhat earlier
+time in other lands, where we have not been able to study the fossils;
+for to make their wonderful forms slowly, as we believe them to have
+been made, would require a very long time. It is probable that during
+the Cretaceous time, in some land where we have not yet had a chance
+to study the rocks, these creatures grew to their varied forms, and
+that in the beginning of the Tertiary time, they spread into the
+regions where we find their bones.
+
+Beginning with the Tertiary time, we find these lower kinsmen of man,
+through whom man came to be. The mammals were marked by much greater
+simplicity and likeness to each other than they now have. There were
+probably no monkeys, no horses, no bulls, no sheep, no goats, no
+seals, no whales, and no bats. All these animals had many-fingered
+feet. There were no cloven feet like those of our bulls, and no solid
+feet as our horses have. Their brains, which by their size give us a
+general idea of the intelligence of the creature, are small; hence we
+conclude that these early mammals were less intelligent than those of
+our day.
+
+It would require volumes to trace the history of the growth of these
+early mammals, and show how they, step by step, came to their present
+higher state. We will take only one of the simplest of these changes,
+which happens to be also the one which we know best. This is the
+change that led to the making of our common horses, which seem to have
+been brought into life on the continent of North America. The most
+singular thing about our horses is that the feet have but one large
+toe or finger, the hoof, the hard covering of which is the nail of
+that extremity. Now it seems hard to turn the weak, five-fingered
+feet of the animals of the lower Tertiary--feet which seem to be
+better fitted for tree-climbing than anything else--into feet such as
+we find in the horse. Yet the change is brought about by easy stages
+that lead the successive creatures from the weak and loose-jointed
+foot of the ancient forms to the solid, single-fingered horse's hoof,
+which is wonderfully well-fitted for carrying a large beast at a swift
+speed, and is so strong a weapon of defence that an active donkey can
+kill a lion with a well-delivered kick.
+
+[Illustration: FIG. 10. FEET OF TERTIARY MAMMALS.]
+
+The oldest of these creatures that lead to the horses is called
+_Eohippus_ or beginning horse. This fellow had on the forefeet four
+large toes, each with a small hoof and fifth imperfect one, which
+answered to the thumb. The hind feet had gone further in the change,
+for they each had but three toes, each with hoofs, the middle-toed
+hoof larger and longer than the others. A little later toward our day
+we find another advance in the _Orohippus_, when the little imperfect
+thumb has disappeared, and there are only four toes on the forefeet
+and three on the hind.
+
+Yet later we have the _Mesohippus_ or half-way horse. There are still
+three toes on the hind foot, but one more of the fingers of the
+forefeet has disappeared. This time it is the little finger that goes,
+leaving only a small bone to show that its going was by a slow
+shrinking. The creature now has three little hoofs on each of its
+feet.
+
+Still nearer our own time comes the _Miohippus_, which shows the two
+side hoofs on each foot shrinking up so that they do not touch the
+ground, but they still bear little hoofs. Lastly, about the time of
+man's coming on the earth, appears his faithful servant, the horse, in
+which those little side hoofs have disappeared, leaving only two
+little "splint" bones to mark the place where these side hoofs belong.
+Thus, step by step, our horses' feet were built up; while these parts
+were changing, the other parts of the animals were also slowly
+altering. They were at first smaller than our horses,--some of them
+not as large as an ordinary Newfoundland dog; others as small as
+foxes.
+
+[Illustration: FIG. 11. DEVELOPMENT OF HORSES'S FOOT.]
+
+As if to remind us of his old shape, our horses now and then, but
+rarely, have, in place of the little splint bones above the hoof, two
+smaller hoofs, just like the foot of _Miohippus_. Sometimes these are
+about the size of a silver dollar, on the part that receives the shoe
+when horses are shod.
+
+In this way, by slow-made changes, the early mammals pass into the
+higher. Out of one original part are made limbs as different as the
+feet of the horse, the wing of a bat, the paddle of a whale, and the
+hand of man. So with all the parts of the body the forms change to
+meet the different uses to which they are put.
+
+At the end of this long promise, which was written in the very first
+animals, comes man himself, in form closely akin to the lower animals,
+but in mind immeasurably apart from them. We can find every part of
+man's body in a little different shape in the monkeys, but his mind is
+of a very different quality. While his lower kindred cannot be made to
+advance in intelligence any more than man himself can grow a horse's
+foot or a bat's wing, he is constantly going higher and higher in his
+mental and moral growth.
+
+So far we have found but few traces of man that lead us to suppose
+that he has been for a long geological time on the earth, yet there is
+good evidence that he has been here for a hundred thousand years or
+more. It seems pretty clear that he has changed little in his body in
+all these thousands of generations. The earliest remains show us a
+large-brained creature, who used tools and probably had already made a
+servant of fire, which so admirably aids him in his work.
+
+Besides the development of this wonderful series of animals, that we
+may call in a certain way our kindred, there have been several other
+remarkable advances in this Tertiary time, this age of crowning
+wonders in the earth's history. The birds have gone forward very
+rapidly; it is likely that there were no songsters at the first part
+of this period, but these singing birds have developed very rapidly in
+later times. Among the insects the most remarkable growth is among the
+ants, the bees, and their kindred. These creatures have very wonderful
+habits; they combine together for the making of what we may call
+states, they care for their young, they wage great battles, they keep
+slaves, they domesticate other insects, and in many ways their acts
+resemble the doings of man. Coming at about the same time as man,
+these intellectual insects help to mark this later stage of the earth
+as the intellectual period in its history. Now for the first time
+creatures are on the earth which can form societies and help each
+other in the difficult work of living.
+
+Among the mollusks, the most important change is in the creation of
+the great, strong swimming squids, the most remarkable creatures of
+the sea. Some of these have arms that can stretch for fifty feet from
+tip to tip.
+
+Among the plants, the most important change has been in the growth of
+flowering plants, which have been constantly becoming more plenty, and
+the plants which bear fruits have also become more numerous. The
+broad-leaved trees seem to be constantly gaining on the forests of
+narrow-leaved cone-bearers, which had in an earlier day replaced the
+forests of ferns.
+
+In these Tertiary ages, as in the preceding times of the earth, the
+lands and seas were much changed in their shape. It seems that in the
+earlier ages the land had been mostly in the shape of large islands
+grouped close together where the continents now are. In this time,
+these islands grew together to form the united lands of Europe, Asia,
+Africa, Australia, and the twin American continents; so that, as life
+rose higher, the earth was better fitted for it. Still there were
+great troubles that it had to undergo. There were at least two
+different times during the Tertiary age termed glacial periods, times
+when the ice covered a large part of the northern continents,
+compelling life of all sorts to abandon great regions, and to find new
+places in more southern lands. Many kinds of animals and plants seem
+to have been destroyed in these journeys; but these times of trial, by
+removing the weaker and less competent creatures, made room for new
+forms to rise in their places. All advance in nature makes death
+necessary, and this must come to races as well as to individuals if
+the life of the world is to go onward and upward.
+
+Looking back into the darkened past, of which we yet know but little
+compared with what we would like to know, we can see the great armies
+of living beings led onward from victory to victory toward the higher
+life of our own time. Each age sees some advance, though death
+overtakes all its creatures. Those that escape their actual enemies or
+accident, fall a prey to old age: volcanoes, earthquakes, glacial
+periods, and a host of other violent accidents sweep away the life of
+wide regions, yet the host moves on under a control that lies beyond
+the knowledge of science. Man finds himself here as the crowning
+victory of this long war. For him all this life appears to have
+striven. In his hands lies the profit of all its toil and pain.
+Surely this should make us feel that our duty to all these living
+things, that have shared in the struggle that has given man his
+elevation, is great, but above all, great is our duty to the powers
+that have been placed in our bodies and our minds.
+
+[Illustration: A GLACIER.]
+
+
+
+
+THE PITCH LAKE IN THE WEST INDIES
+
+(FROM AT LAST.)
+
+BY C. KINGSLEY.
+
+
+[Illustration: COOLIE AND NEGRO.]
+
+The Pitch Lake, like most other things, owes its appearance on the
+surface to no convulsion or vagary at all, but to a most slow,
+orderly, and respectable process of nature, by which buried vegetable
+matter, which would have become peat, and finally brown coal, in a
+temperate climate, becomes, under the hot tropic soil, asphalt and
+oil, continually oozing up beneath the pressure of the strata above
+it....
+
+       *       *       *       *       *
+
+As we neared the shore, we perceived that the beach was black with
+pitch; and the breeze being off the land, the asphalt smell (not
+unpleasant) came off to welcome us. We rowed in, and saw in front of a
+little row of wooden houses a tall mulatto, in blue policeman's dress,
+gesticulating and shouting to us. He was the ward policeman, and I
+found him (as I did all the colored police) able and courteous, shrewd
+and trusty. These police are excellent specimens of what can be made
+of the negro, or half-negro, if he be but first drilled, and then
+given a responsibility which calls out his self-respect. He was
+warning our crew not to run aground on one or other of the pitch
+reefs, which here take the place of rocks. A large one, a hundred
+yards off on the left, has been almost all dug away, and carried to
+New York or to Paris to make asphalt-pavement.
+
+[Illustration: THE POLICE STATION.]
+
+The boat was run ashore, under his directions, on a spit of sand
+between the pitch; and when she ceased bumping up and down in the
+muddy surf, we scrambled out into a world exactly the hue of its
+inhabitants of every shade, from jet black to copper-brown. The
+pebbles on the shore were pitch. A tide-pool close by was enclosed in
+pitch; a four-eyes was swimming about in it, staring up at us; and
+when we hunted him, tried to escape, not by diving, but by jumping on
+shore on the pitch, and scrambling off between our legs. While the
+policeman, after profoundest courtesies, was gone to get a mule-cart
+to take us up to the lake, and planks to bridge its water channels,
+we took a look round at this oddest of corners of the earth.
+
+In front of us was the unit of civilization,--the police-station,
+wooden, on wooden stilts (as all well-built houses are here), to
+insure a draught of air beneath them. We were, of course, asked to
+come in and sit down, but preferred looking about, under our
+umbrellas; for the heat was intense. The soil is half pitch, half
+brown earth, among which the pitch sweals in and out as tallow sweals
+from a candle. It is always in slow motion under the heat of the
+tropic sun; and no wonder if some of the cottages have sunk right and
+left in such a treacherous foundation. A stone or brick house could
+not stand here; but wood and palm-thatch are both light and tough
+enough to be safe, let the ground give way as it will.
+
+The soil, however, is very rich. The pitch certainly does not injure
+vegetation, though plants will not grow actually in it. The first
+plants which caught our eyes were pine-apples, for which La Brea is
+famous. The heat of the soil, as well as the air, brings them to
+special perfection. They grow about anywhere, unprotected by hedge or
+fence; for the negroes here seem honest enough, at least toward each
+other; and at the corner of the house was a bush worth looking at, for
+we had heard of it for many a year. It bore prickly, heart-shaped pods
+an inch long, filled with seeds coated with a red waxy pulp.
+
+This was a famous plant--_Bixa orellana Roucou_; and that pulp was the
+well-known annotto dye of commerce. In England and Holland it is used
+merely, I believe, to color cheeses, but in the Spanish Main to color
+human beings. The Indian of the Orinoco prefers paint to clothes; and
+when he has "roucoued" himself from head to foot, considers himself in
+full dress, whether for war or dancing. Doubtless he knows his own
+business best from long experience. Indeed, as we stood broiling on
+the shore, we began somewhat to regret that European manners and
+customs prevented our adopting the Guaraon and Arrawak fashion.
+
+[Illustration: THE MULE-CART.]
+
+The mule-cart arrived; the lady of the party was put into it on a
+chair, and slowly bumped and rattled past the corner of Dundonald
+Street--so named after the old sea-hero, who was, in his life-time,
+full of projects for utilizing this same pitch--and up in pitch road,
+with a pitch gutter on each side.
+
+The pitch in the road has been, most of it, laid down by hand, and is
+slowly working down the slight incline, leaving pools and ruts full of
+water, often invisible, because covered with a film of brown
+pitch-dust, and so letting in the unwary walker over his shoes. The
+pitch in the gutter-bank is in its native place, and as it spues
+slowly out of the soil into the ditch in odd wreaths and lumps, we
+could watch, in little, the process which has produced the whole
+deposit--probably the whole lake itself.
+
+A bullock-cart, laden with pitch, came jolting down past us, and we
+observed that the lumps, when the fracture is fresh, have all a drawn
+out look; that the very air bubbles in them, which are often very
+numerous, are all drawn out likewise, long and oval, like the
+air-bubbles in some ductile lavas.
+
+On our left, as we went on, the bush was low, all of yellow cassia and
+white Hibiscus, and tangled with lovely convolvulus-like creepers,
+Ipomoea and Echites, with white, purple or yellow flowers. On the
+right were negro huts and gardens, fewer and fewer as we went on,--all
+rich with fruit trees, especially with oranges, hung with fruit of
+every hue; and beneath them, of course, the pine-apples of La Brea.
+Everywhere along the road grew, seemingly wild here, that pretty low
+tree, Cashew, with rounded yellow-veined leaves and little green
+flowers, followed by a quaint pink and red-striped pear, from which
+hangs, at the larger and lower end, a kidney-shaped bean, which bold
+folk eat when roasted; but woe to those who try it when raw; for the
+acrid oil blisters the lips, and even while the beans are roasting the
+fumes of the oil will blister the cook's face if she holds it too near
+the fire.
+
+As we went onward up the gentle slope (the rise is one hundred and
+thirty-eight feet in rather more than a mile), the ground became more
+and more full of pitch, and the vegetation poorer and more rushy,
+till it resembled, on the whole, that of an English fen. An Ipomoea or
+two, and a scarlet flowered dwarf Heliconia, kept up the tropic type,
+as does a stiff brittle fern about two feet high. We picked the weeds,
+which looked like English mint or basil, and found that most of them
+had three longitudinal nerves in each leaf, and were really
+Melastomas, though dwarfed into a far meaner habit than that of the
+noble forms we saw at Chaguanas, and again on the other side of the
+lake. On the right, too, in a hollow, was a whole wood of Groogroo
+palms, gray stemmed, gray leaved, and here and there a patch of white
+or black Roseau rose gracefully eight or ten feet high among the
+reeds.
+
+The plateau of pitch now widened out, and the whole ground looked like
+an asphalt pavement, half overgrown with marsh-loving weeds, whose
+roots feed in the sloppy water which overlies the pitch. But, as yet,
+there was no sign of the lake. The incline, though gentle, shuts off
+the view of what is beyond. This last lip of the lake has surely
+overflowed, and is overflowing still, though very slowly. Its furrows
+all curve downward; and it is, in fact, as one of our party said, "a
+black glacier." The pitch, expanding under the burning sun of day,
+must needs expand most toward the line of least resistance--that is,
+downhill; and when it contracts again under the coolness of night, it
+contracts, surely, from the same cause, more downhill than uphill; and
+so each particle never returns to the spot whence it started, but
+rather drags the particles above it downward toward itself. At least,
+so it seemed to us. Thus may be explained the common mistake which is
+noticed by Messrs. Wall and Sawkins in their admirable description of
+the lake.
+
+"All previous descriptions refer the bituminous matter scattered over
+the La Brea district, and especially that between the village and the
+lake, to streams which have issued at some former epoch from the lake,
+and extended into the sea. This supposition is totally incorrect, as
+solidification would probably have ensued before it had proceeded
+one-tenth of the distance; and such of the asphalt as has undoubtedly
+escaped from the lake has not advanced more than a few yards, and
+always presents the curved surfaces already described, and never
+appears as an extended sheet."
+
+Agreeing with this statement as a whole, I nevertheless cannot but
+think it probable that a great deal of the asphalt, whether it be in
+large masses or in scattered veins, may be moving very slowly down
+hill, from the lake to the sea, by the process of expansion by day and
+contraction by night, and may be likened to a caterpillar, or rather
+caterpillars innumerable, progressing by expanding and contracting
+their rings, having strength enough to crawl down hill, but not
+strength enough to back up hill again.
+
+At last we surmounted the last rise, and before us lay the famous
+lake--not at the bottom of a depression, as we expected, but at the
+top of a rise, whence the ground slopes away from it on two sides, and
+rises from it very slightly on the two others. The black pool glared
+and glittered in the sun. A group of islands, some twenty yards wide,
+were scattered about the middle of it. Beyond it rose a double forest
+of Moriche fan-palms; and to the right of them high wood with giant
+Mombins and undergrowth of Cocorite--a paradise on the other side of
+the Stygian pool.
+
+[Illustration: THE PITCH LAKE.]
+
+We walked, with some misgivings, on to the asphalt, and found it
+perfectly hard. In a few steps we were stopped by a channel of clear
+water, with tiny fish and water-beetles in it; and, looking round, saw
+that the whole lake was intersected with channels, so unlike anything
+which can be seen elsewhere that it is not easy to describe them.
+
+Conceive a crowd of mushrooms, of all shapes, from ten to fifty feet
+across, close together side by side, their tops being kept at exactly
+the same level, their rounded rims squeezed tight against each other;
+then conceive water poured on them so as to fill the parting seams,
+and in the wet season, during which we visited it, to overflow the
+tops somewhat. Thus would each mushroom represent, tolerably well, one
+of the innumerable flat asphalt bosses, which seem to have sprung up
+each from a separate centre, while the parting seams would be of much
+the same shape as those in the asphalt, broad and shallow atop, and
+rolling downward in a smooth curve, till they are at bottom mere
+cracks from two to ten feet deep. Whether these cracks actually close
+up below, and the two contiguous masses of pitch become one, cannot be
+seen. As far as the eye goes down, they are two, though pressed close
+to each other. Messrs. Wall and Sawkins explain the odd fact clearly
+and simply. The oil, they say, which the asphalt contains when it
+rises first, evaporates in the sun, of course most on the outside of
+the heap, leaving a thorough coat of asphalt, which has, generally, no
+power to unite with the corresponding coat of the next mass. Meanwhile
+Mr. Manross, an American gentleman, who has written a very clever and
+interesting account of the lake, seems to have been so far deceived by
+the curved and squeezed edges of these masses that he attributes to
+each of them a revolving motion, and supposes that the material is
+continually passing from the centre to the edges, when it "rolls
+under," and rises again in the middle. Certainly the strange stuff
+looks, at the first glance, as if it were behaving in this way; and
+certainly, also, his theory would explain the appearance of sticks and
+logs in the pitch. But Messrs. Wall and Sawkins say that they have
+observed no such motion: nor did we; and I agree with them, that it is
+not very obvious to what force, or what influence, it could be
+attributable. We must, therefore, seek some other way of accounting
+for the sticks--which utterly puzzled us, and which Mr. Manross well
+describes as "numerous pieces of wood, which, being involved in the
+pitch, are constantly coming to the surface. They are often several
+feet in length, and five or six inches in diameter. On reaching the
+surface they generally assume an upright position, one end being
+detained in the pitch, while the other is elevated by the lifting of
+the middle. They may be seen at frequent intervals over the lake,
+standing up to the height of two or even three feet. They look like
+stumps of trees protruding through the pitch; but their parvenu
+character is curiously betrayed by a ragged cap of pitch which
+invariably covers the top, and hangs down like hounds' ears on either
+side."
+
+Whence do they come? Have they been blown on to the lake, or left
+behind by man? or are they fossil trees, integral parts of the
+vegetable stratum below which is continually rolling upward? or are
+they of both kinds? I do not know. Only this is certain, as Messrs.
+Wall and Sawkins have pointed out, that not only "the purer varieties
+of asphalt, such as approach or are identical with asphalt glance,
+have been observed" (though not, I think, in the lake itself) "in
+isolated masses, where there was little doubt of their proceeding from
+ligneous substances of larger dimensions, such as roots and pieces of
+trunks and branches," but, moreover, that "it is also necessary to
+admit a species of conversion by contact, since pieces of wood
+included accidentally in the asphalt, for example, by dropping from
+overhanging vegetation, are often found partially transformed into the
+material." This is a statement which we verified again and again, as
+we did the one which follows, namely, that the hollow bubbles which
+abound on the surface of the pitch "generally contain traces of the
+lighter portion of vegetation," and "are manifestly derived from
+leaves, etc., which are blown about the lake by the wind, and are
+covered with asphalt, and, as they become asphalt themselves, give off
+gases which form bubbles round them."
+
+But how is it that those logs stand up out of the asphalt, with
+asphalt caps and hounds' ears (as Mr. Manross well phrases it) on the
+tops of them?
+
+We pushed on across the lake, over the planks which the negroes laid
+down from island to island. Some, meanwhile, preferred a steeple-chase
+with water-jumps, after the fashion of the midshipmen on a certain
+second visit to the lake. How the negroes grinned delight and surprise
+at the vagaries of English lads--a species of animal altogether new to
+them; and how they grinned still more when certain staid and portly
+dignitaries caught the infection, and proved by more than one good
+leap that they too had been English school-boys--alas! long, long ago.
+
+So, whether by bridging, leaping, or wading, we arrived at the little
+islands, and found them covered with a thick, low scrub; deep sedge,
+and among them Pinguins, like huge pine-apples without the apple; gray
+wild-pines, parasites on Matapalos, which, of course, have established
+themselves, like robbers and vagrants as they are, everywhere; a true
+holly, with box-like leaves; and a rare cocoa-plum, very like the
+holly in habit, which seems to be all but confined to these little
+patches of red earth, afloat on the pitch. Out of the scrub, when we
+were there, flew off two or three night-jars, very like our English
+species, save that they had white in the wings; and on the second
+visit one of the midshipmen, true to the English boy's bird's-nesting
+instinct, found one of their eggs, white-spotted, in a grass nest.
+
+Passing these little islands, which are said (I know not how truly) to
+change their places and number, we came to the very fountains of Styx,
+to that part of the lake where the asphalt is still oozing up.
+
+As the wind set toward us, we soon became aware of an evil
+smell--petroleum and sulphureted hydrogen at once--which gave some of
+us a headache. The pitch here is yellow and white with sulphur foam;
+so are the water-channels; and out of both water and pitch innumerable
+bubbles of gas arise, loathsome to the smell. We became aware that the
+pitch was soft under our feet. We left the impression of our boots;
+and if we had stood still awhile, we should soon have been ankle-deep.
+No doubt there are spots where, if a man stayed long enough, he would
+be slowly and horribly engulfed. "But," as Mr. Manross says truly, "in
+no place is it possible to form those bowl-like depressions round the
+observer described by former travellers." What we did see is that the
+fresh pitch oozes out at the lines of least resistance, namely, in the
+channels between the older and more hardened masses, usually at the
+upper ends of them, so that one may stand on pitch comparatively hard,
+and put one's hand into pitch quite liquid, which is flowing softly
+out, like some ugly fungoid growth, such as may be seen in old
+wine-cellars, into the water. One such pitch-fungus had grown several
+yards in length in the three weeks between our first and second visit;
+and on another, some of our party performed exactly the same feat as
+Mr. Manross.
+
+"In one of the star-shaped pools of water, some five feet deep, a
+column of pitch had been forced perpendicularly up from the bottom. On
+reaching the surface of the water it had formed a sort of
+centre-table, about four feet in diameter, but without touching the
+sides of the pool. The stem was about a foot in diameter. I leaped out
+on this table, and found that it not only sustained my weight, but
+that the elasticity of the stem enabled me to rock it from side to
+side. Pieces torn from the edges of this table sank readily, showing
+that it had been raised by pressure, and not by its buoyancy."
+
+True, though strange; but stranger still did it seem to us when we did
+at last what the negroes asked us, and dipped our hands into the
+liquid pitch, to find that it did not soil the fingers. The old
+proverb that one cannot touch pitch without being defiled happily does
+not stand true here, or the place would be intolerably loathsome. It
+can be scraped up, moulded into any shape you will, wound in a string
+(as was done by one of the midshipmen) round a stick, and carried off;
+but nothing is left on the hand save clean gray mud and water. It may
+be kneaded for an hour before the mud be sufficiently driven out of it
+to make it sticky. This very abundance of earthy matter it is which,
+while it keeps the pitch from soiling, makes it far less valuable than
+it would be were it pure.
+
+It is easy to understand whence this earthy matter (twenty or thirty
+per cent) comes. Throughout the neighborhood the ground is full, to
+the depth of hundreds of feet, of coaly and asphaltic matter. Layers
+of sandstone or of shale containing this decayed vegetable alternate
+with layers which contain none; and if, as seems probable, the coaly
+matter is continually changing into asphalt and oil, and then working
+its way upward through every crack and pore, to escape from the
+enormous pressure of the superincumbent soil, it must needs carry up
+with it innumerable particles of the soils through which it passes.
+
+In five minutes we had seen, handled, and smelt enough to satisfy us
+with this very odd and very nasty vagary of tropic nature; and as we
+did not wish to become faint and ill between the sulphureted hydrogen
+and the blaze of the sun reflected off the hot black pitch, we hurried
+on over the water-furrows, and through the sedge-beds to the farther
+shore--to find ourselves, in a single step, out of an Inferno into a
+Paradise.
+
+[Illustration]
+
+
+
+
+A STALAGMITE CAVE
+
+(FROM THE VOYAGE OF THE CHALLENGER.)
+
+BY SIR C. WYVILLE THOMSON, KT., LL.D., ETC.
+
+
+[Illustration]
+
+I think the Painter's Vale cave is the prettiest of the whole. The
+opening is not very large. It is an arch over a great mass of debris
+forming a steep slope into the cave, as if part of the roof of the
+vault had suddenly fallen in. At the foot of the bank of debris one
+can barely see in the dim light the deep clear water lying perfectly
+still and reflecting the roof and margin like a mirror. We clambered
+down the slope, and as the eye became more accustomed to the obscurity
+the lake stretched further back. There was a crazy little punt moored
+to the shore, and after lighting candles Captain Nares rowed the
+Governor back into the darkness, the candles throwing a dim light for
+a time--while the voices became more hollow and distant--upon the
+surface of the water and the vault of stalactite, and finally passing
+back as mere specks into the silence.
+
+[Illustration: A GUIDE.]
+
+After landing the Governor on the opposite side, Captain Nares
+returned for me, and we rowed round the weird little lake. It was
+certainly very curious and beautiful; evidently a huge cavity out of
+which the calcareous sand had been washed or dissolved, and whose
+walls, still to a certain extent permeable, had been hardened and
+petrified by the constant percolation of water charged with carbonate
+of lime. From the roof innumerable stalactites, perfectly white, often
+several yards long and coming down to the delicacy of knitting-needles,
+hung in clusters; and wherever there was any continuous crack in the
+roof or wall, a graceful, soft-looking curtain of white stalactite
+fell, and often ended, much to our surprise. Deep in the water
+Stalagmites also rose up in pinnacles and fringes through the water,
+which was so exquisitely still and clear that it was something
+difficult to tell where the solid marble tracery ended, and its
+reflected image began. In this cave, which is a considerable distance
+from the sea, there is a slight change of level with the tide
+sufficient to keep the water perfectly pure. The mouth of the cave is
+overgrown with foliage, and every tree is draped and festooned with
+the fragrant _Jasminum gracile_, mingled not unfrequently with the
+"poison ivy" (_Rhus toxicodendron_). The Bermudians, especially the
+dark people, have a most exaggerated horror of this bush. They imagine
+that if one touch it or rub against it he becomes feverish, and is
+covered with an eruption. This is no doubt entirely mythical. The
+plant is very poisonous, but the perfume of the flower is rather
+agreeable, and we constantly plucked and smelt it without its
+producing any unpleasant effect. The tide was with us when we regained
+the Flats Bridge, and the galley shot down the rapid like an arrow,
+the beds of scarlet sponges and the great lazy trepangs showing
+perfectly clearly on the bottom at a fathom depth.
+
+[Illustration: FIG. 1. CALCAREOUS CONCRETION SIMULATING A FOSSIL
+PALM-STEM, BOAZ ISLAND, BERMUDAS.]
+
+Every here and there throughout the islands there are groups of bodies
+of very peculiar form projecting from the surface of the limestone
+where it has been weathered. These have usually been regarded as
+fossil palmetto stumps, the roots of trees which have been overwhelmed
+with sand and whose organic matter has been entirely removed and
+replaced by carbonate of lime. Fig. 1 represents one of the most
+characteristic of these from a group on the side of the road in Boaz
+Island. It is a cylinder a foot in diameter and six inches or so high;
+the upper surface forms a shallow depression an inch deep surrounded
+by a raised border; the bottom of the cup is even, and pitted over
+with small depressions like the marks of rain-drops on sand; the walls
+of the cylinder seem to end a few inches below the surface of the
+limestone in a rounded boss, and all over this there are round
+markings or little cylindrical projections like the origins of
+rootlets. The object certainly appears to agree even in every detail
+with a fossil palm-root, and as the palmetto is abundant on the
+islands and is constantly liable to be destroyed by and ultimately
+enveloped in a mass of moving sand, it seemed almost unreasonable to
+question its being one. Still something about the look of these things
+made me doubt, with General Nelson, whether they were fossil palms, or
+indeed whether they were of organic origin at all; and after carefully
+examining and pondering over several groups of them, at Boaz Island,
+on the shore at Mount Langton, and elsewhere, I finally came to the
+conclusion that they were not fossils, but something totally
+different.
+
+[Illustration: FIG. 2. CALCAREOUS CONCRETION IN AEOLIAN LIMESTONE,
+BERMUDAS.]
+
+[Illustration: FIG. 3. CALCAREOUS CONCRETION IN AEOLIAN LIMESTONE,
+BERMUDAS.]
+
+[Illustration: FIG. 4. CALCAREOUS CONCRETION, BERMUDAS.]
+
+[Illustration: FIG. 5. CALCAREOUS CONCRETION IN AEOLIAN LIMESTONE,
+BERMUDAS.]
+
+The form given in Fig. 1 is the most characteristic, and probably by
+far the most common; but very frequently one of a group of these, one
+which is evidently essentially the same as the rest and formed in the
+same way, has an oval or an irregular shape (Figs. 2, 3, and 4). In
+these we have the same raised border, the same scars on the outside,
+the same origins of root-like fibres, and the same pitting of the
+bottom of the shallow cup; but their form precludes the possibility of
+their being tree-roots. In some cases (Fig. 5), a group of so-called
+"palm-stems" is inclosed in a space surrounded by a ridge, and on
+examining it closely this outer ridge is found to show the same
+leaf-scars and traces of rootlets as the "palm-stems" themselves. In
+some cases very irregular honey-combed figures are produced which the
+examination of a long series of intermediate forms shows to belong to
+the same category (Fig. 6).
+
+[Illustration: FIG. 6. CONCRETIONS IN AEOLIAN ROCKS, BERMUDAS.]
+
+In the caves in the limestone, owing to a thread of water having found
+its way in a particular direction through the porous stone of the
+roof, a drop falls age after age on one spot on the cave-floor,
+accurately directed by the stalactite which it is all the time
+creating. The water contains a certain proportion of carbonate of
+lime, which is deposited as stalagmite as the water evaporates, and
+thus a ring-like crust is produced at a little distance from the spot
+where the drop falls. When a ring is once formed, it limits the spread
+of the drop, and determines the position of the wall bounding the
+little pool made by the drop. The floor of the cave gradually rises by
+the accumulation of sand and travertine, and with it rise the walls
+and floor of the cup by the deposit of successive layers of stalagmite
+produced by the drop percolating into the limestone of the floor which
+hardens it still further, but in this peculiar symmetrical way. From
+the floor and sides of the cup the water oozes into the softer
+limestone around and beneath; but, as in all these limestones, it does
+not ooze indiscriminately, but follows certain more free paths. These
+become soon lined and finally blocked with stalagmite, and it is
+these tubes and threads of stalagmite which afterwards in the
+pseudo-fossil represent the diverging rootlets.
+
+[Illustration: A STALAGMITE CAVE.]
+
+Sometimes when two or more drops fall from stalactites close to one
+another the cups coalesce (Figs. 2, 3, and 4); sometimes one drop or
+two is more frequent than the other, and then we have the form shown
+in Figs. 3 and 4; sometimes many drops irregularly scattered form a
+large pool with its raised border, and a few drops more frequent and
+more constant than the rest grow their "palmetto stems" within its
+limit (Fig. 5); and sometimes a number of drops near one another make
+a curious regular pattern, with the partitions between the recesses
+quite straight (Fig. 6).
+
+I have already referred to the rapid denudation which is going on in
+these islands, and to the extent to which they have been denuded
+within comparatively recent times. The floors of caves, from their
+being cemented into a nearly homogeneous mass by stalagmitic matter,
+are much harder than the ordinary porous blown limestone; and it seems
+that in many cases, after the rocks forming the walls and roof have
+been removed, disintegration has been at all events temporarily
+arrested by the floor. Where there is a flat surface of rock exposed
+anywhere on the island, it very generally bears traces of having been
+at one time the floor of a cave; and as the weather-wearing of the
+surface goes on, the old concretionary structures are gradually
+brought out again, the parts specially hardened by a localized slow
+infiltration of lime resist integration longest and project above the
+general surface. Often a surface of weathered rock is so studded with
+these symmetrical concretions, that it is hard to believe that one is
+not looking at the calcified stumps of a close-growing grove of palms.
+
+[Illustration]
+
+
+
+
+THE BIG TREES OF CALIFORNIA
+
+(FROM STUDIES SCIENTIFIC AND SOCIAL.)
+
+BY ALFRED RUSSEL WALLACE.
+
+
+[Illustration]
+
+In the popular accounts of these trees it is usual to dwell only on
+the dimensions of the very largest known specimens, and sometimes even
+to exaggerate these. Even the smaller full-grown trees, however, are
+of grand dimensions, varying from fourteen to eighteen feet in
+diameter, at six feet above the ground, and keeping nearly the same
+thickness for perhaps a hundred feet. In the south Calaveras grove,
+where there are more than a thousand trees, the exquisite beauty of
+the trunks is well displayed by the numerous specimens in perfect
+health and vigor. The bark of these trees, seen at a little distance,
+is of a bright orange brown tint, delicately mottled with darker
+shades, and with a curious silky or plush-like gloss, which gives them
+a richness of color far beyond that of any other conifer. The tree
+which was cut down soon after the first discovery of the species, the
+stump of which is now covered with a pavilion, is twenty-five feet in
+diameter at six feet above the ground, but this is without the thick
+bark, which would bring it to twenty-seven feet when alive. A
+considerable portion of this tree still lies where it fell, and at one
+hundred and thirty feet from the base I found it to be still twelve
+and a half feet in diameter (or fourteen feet with the bark), while at
+the extremity of the last piece remaining, two hundred and fifteen
+feet from its base, it is six feet in diameter, or at least seven feet
+with the bark. The height of this tree when it was cut down is not
+recorded, but as one of the living trees is more than three hundred
+and sixty feet high, it is probable that this giant was not much short
+of four hundred feet.
+
+[Illustration: THE "MOTHER OF THE FOREST."]
+
+In the accompanying picture the dead tree in the centre is that from
+which the bark was stripped, which was erected in the Crystal Palace
+and unfortunately destroyed by fire. It is called the "Mother of the
+Forest." The two trees nearer the foreground are healthy, medium-sized
+trees, about fifteen feet diameter at six feet above the ground.
+
+The huge decayed trunk called "Father of the Forest," which has fallen
+perhaps a century or more, exhibits the grandest dimensions of any
+known tree. By measuring its remains, and allowing for the probable
+thickness of the bark, it seems to have been about thirty-five feet
+diameter near the ground, at ninety feet up fifteen feet, and even at
+a height of two hundred and seventy feet, it was nine feet in
+diameter. It is within the hollow trunk of this tree that a man on
+horse-back can ride--both man and horse being rather small; but the
+dimensions undoubtedly show that it was considerably larger than the
+"Pavilion tree," and that it carried its huge dimensions to a greater
+altitude; and although this does not prove it to have been much
+taller, yet it was in all probability more than four hundred feet in
+height.
+
+[Illustration]
+
+Very absurd statements are made to visitors as to the antiquity of
+these trees, three or four thousand years being usually given as their
+age. This is founded on the fact that while many of the large Sequoias
+are greatly damaged by fire, the large pines and firs around them are
+quite uninjured. As many of these pines are assumed to be near a
+thousand years old, the epoch of the "great fire" is supposed to be
+earlier still, and as the Sequoias have not outgrown the fire-scars in
+all that time, they are supposed to have then arrived at their full
+growth. But the simple explanation of these trees alone having
+suffered so much from fire is, that their bark is unusually thick,
+dry, soft, and fibrous, and it thus catches fire more easily and
+burns more readily and for a longer time than that of the other
+coniferae. Forest fires occur continually, and the visible damage done
+to these trees has probably all occurred in the present century.
+Professor C.B. Bradley, of the University of California, has carefully
+counted the rings of annual growth on the stump of the "Pavilion
+tree," and found them to be twelve hundred and forty; and after
+considering all that has been alleged as to the uncertainty of this
+mode of estimating the age of a tree, he believes that in the climate
+of California, in the zone of altitude where these trees grow, the
+seasons of growth and repose are so strongly marked that the number of
+annual rings gives an accurate result.
+
+Other points that have been studied by Professor Bradley are, the
+reason why there are so few young trees in the groves, and what is the
+cause of the destruction of the old trees. To take the last point
+first, these noble trees seem to be singularly free from disease or
+from decay due to old age. All the trees that have been cut down are
+solid to the heart, and none of the standing trees show any
+indications of natural decay. The only apparent cause for their
+overthrow is the wind, and by noting the direction of a large number
+of fallen trees it is found that the great majority of them lie more
+or less towards the south. This is not the direction of the prevalent
+winds, but many of the tallest trees lean towards the south, owing to
+the increased growth of their topmost branches towards the sun. They
+are then acted upon by violent gales, which loosen their roots, and
+whatever the direction of the wind that finally overthrows them, they
+fall in the direction of the over-balancing top weight. The young
+trees grow spiry and perfectly upright, but as soon as they overtop
+the surrounding trees and get the full influence of the sun and wind,
+the highest branches grow out laterally, killing those beneath their
+shade, and thus a dome-shaped top is produced. Taking into
+consideration the health and vigor of the largest trees, it seems
+probable that, under favorable conditions of shelter from violent
+winds, and from a number of trees around them of nearly equal height,
+big trees might be produced far surpassing in height and bulk any that
+have yet been discovered. It is to be hoped that if any such are found
+to exist in the extensive groves of these trees to the south of those
+which are alone accessible to tourists, the Californian Government
+will take steps to reserve a considerable tract containing them, for
+the instruction and delight of future generations.
+
+The scarcity of young Sequoias strikes every visitor, the fact being
+that they are only to be found in certain favored spots. These are,
+either where the loose debris of leaves and branches which covers the
+ground has been cleared away by fire, or on the spots where trees have
+been uprooted. Here the young trees grow in abundance, and serve to
+replace those that fall. The explanation of this is, that during the
+long summer drought the loose surface debris is so dried up that the
+roots of the seedling Sequoias perish before they can penetrate the
+earth beneath. They require to germinate on the soil itself, and this
+they are enabled to do when the earth is turned up by the fall of a
+tree, or where a fire has cleared off the debris. They also flourish
+under the shade of the huge fallen trunks in hollow places, where
+moisture is preserved throughout the summer. Most of the other
+conifers of these forests, especially the pines, have much larger
+seeds than the Sequoias, and the store of nourishment in these more
+bulky seeds enables the young plants to tide over the first summer's
+drought. It is clear, therefore, that there are no indications of
+natural decay in these forest giants. In every stage of their growth
+they are vigorous and healthy, and they have nothing to fear except
+from the destroying hand of man.
+
+[Illustration: REDWOOD TREE WITH TRIPLE TRUNK.]
+
+Destruction from this cause is, however, rapidly diminishing both the
+giant Sequoia and its near ally the noble redwood (_Sequoia
+sempervirens_), a tree which is more beautiful in foliage and in some
+other respects more remarkable than its brother species, while there
+is reason to believe that under favorable conditions it reaches an
+equally phenomenal size. It once covered almost all the coast ranges
+of central and northern California, but has been long since cleared
+away in the vicinity of San Francisco, and greatly diminished
+elsewhere. A grove is preserved for the benefit of tourists near Santa
+Cruz, the largest tree being two hundred and ninety-six feet high,
+twenty-nine feet diameter at the ground and fifteen feet at six feet
+above it. One of these trees having a triple trunk is here figured
+from a photograph. Much larger trees, however, exist in the great
+forests of this tree in the northern part of the State; but these are
+rapidly being destroyed for the timber, which is so good and durable
+as to be in great demand. Hence Californians have a saying that the
+redwood is too good a tree to live. On the mountains a few miles east
+of the Bay of San Francisco, there are a number of patches of young
+redwoods, indicating where large trees have been felled, it being a
+peculiarity of this tree that it sends up vigorous young plants from
+the roots of old ones immediately around the base. Hence in the
+forests these trees often stand in groups arranged nearly in a circle,
+thus marking out the size of the huge trunks of their parents. It is
+from this quality that the tree has been named _sempervirens_, or ever
+flourishing. Dr. Gibbons, of Alameda, who has explored all the remains
+of the redwood forests in the neighborhood of Oakland, kindly took me
+to see the old burnt-out stump of the largest tree he had discovered.
+It is situated about fifteen hundred feet above the sea, and is
+thirty-four feet in diameter at the ground. This is as large as the
+very largest specimens of the _Sequoia gigantea_, but it may have
+spread out more at the base and have been somewhat smaller above,
+though this is not a special characteristic of the species.
+
+[Illustration]
+
+
+
+
+WHAT IS EVOLUTION?
+
+(FROM THE ATLANTIC MONTHLY, MARCH, '93.)
+
+BY PROFESSOR E.S. HOLDEN.
+
+
+[Illustration]
+
+I was once trying to tell a boy, a friend of mine, what the scientific
+men mean by the long word _Evolution_, and to give him some idea of
+the plan of the world. I wanted an illustration of something that had
+grown--evolved, developed--from small beginnings up through more and
+more complicated forms, till it had reached some very complete form. I
+could think of no better example than the railway by which we were
+sitting. The trains were running over the very track where a
+wagon-road had lately been, and before that a country cart-track, and
+before that a bridle-path, and before that again a mere trail for
+cattle. So I took the road for an example, and tried to show my boy
+how it had grown from little things by slow degrees according to laws;
+and if you like, I will try to tell it again.
+
+Just as one can go further and further back, and always find a bird to
+be the parent of the egg, and an egg to be the parent of that bird, so
+in the history of this road of ours; we may go back and back into the
+past, always finding something earlier, which is the cause of the
+something later. The earth, the planets, and the sun were all a fiery
+mist long ago. And in that mist, and in what came before it, we may
+look for the origin of things as they are. But we must begin
+somewhere. Let us begin with the landscape as we see it now,--hills,
+valleys, streams, mountains, grass,--but with only a single tree.
+
+We will not try to say how the tree came there. At least, we will not
+try just yet. When we are through with the story you can say just as
+well as I can.
+
+Suppose, then, a single oak-tree stood just on that hillside thousands
+and thousands of years ago. Grass was growing everywhere, and flowers,
+too. The seeds came with the winds. Year after year the oak-tree bore
+its acorns, hundreds and hundreds of them, and they fell on the grass
+beneath and rolled down the smooth slopes, and sprouted as best they
+could,--most of them uselessly so far as producing trees were
+concerned,--but each one did its duty and furnished its green sprout,
+and died if it found no nourishment.
+
+All the hundreds of acorns rolled down the slopes, Not one rolled up;
+and here was a _law_,--the law of gravitation,--in full activity.
+There were scores of other laws active, too; for evolution had gone a
+long way when we had an earth fit to be lived on, and hills in their
+present shape, and a tree bearing acorns that would reproduce their
+kind. But ever since the fiery mist this simple law of gravitation has
+been acting, binding the whole universe together, making a
+relationship between each clod and every other clod, and forcing
+every stone, every acorn, and every rain-drop to move down and not up.
+
+Just as this law operates,--continuously, silently, inexorably,--so
+every other law makes itself felt in its own sphere. Gravitation is
+simple. The law according to which an acorn makes an oak--and not a
+pine-tree is complex. But the laws of Nature are all alike, and if we
+understand the simple ones, we can at least partly comprehend the more
+complex. They are nothing but fixed habits on a large scale.
+
+So the acorns fell year by year and sprouted; and one out of a
+thousand found good soil, and was not wasted, and made a tree. And so
+all around (below) the tree with which we started there grew a grove
+of oaks like it, in fact its children; and finally the original trees
+died, but not without having left successors.
+
+First of all, the green hillside is smooth and untrodden. There is
+nothing but grass and flowers, borne there by the winds, which leave
+no track. There is no animal life even in this secluded spot save the
+birds, and they too leave no track. By and by there comes a hard
+winter, or a dearth of food, and a pair of stray squirrels emigrate
+from their home in the valley below; and the history of our hill and
+its woods begins. Mere chance decides the choice of the particular
+oak-tree in which the squirrels make their home. From the foot of this
+tree they make excursions here and there for their store of winter
+food,--acorns and the like,--and they leave little paths on the
+hillside from tree to tree.
+
+The best-marked paths run to the places where there are the most
+acorns. A little later on there are more squirrels in the colony,--the
+young of the parent pair, and other colonists from the valley. The
+little tracks become plainer and plainer.
+
+Later still come other wild animals in search of food,--squirrels will
+do. The wild animals do not remain in the colony (there are too few
+squirrels, and they are too hard to catch), but they pass through it,
+sometimes by day but oftenest by night.
+
+You might think it was perfectly a matter of chance along which path a
+bear or a wolf passed, but it was not. He _could_ walk anywhere on the
+hillside; and sometimes he would be found far out of the paths that
+the squirrels had begun. But usually, when he was in no haste, he took
+the easiest path. The easiest one was that which went between the
+bushes and not through them; along the hillside and not straight up
+it; around the big rocks and not over them. The wolves and bears and
+foxes have new and different wants when they come; and they break new
+paths to the springs where they drink, to the shade where they lie, to
+the hollow trees where the bees swarm and store the wild honey.
+
+But the squirrels were the first surveyors of these tracks. The bears
+and wolves are the engineers, who change the early paths to suit their
+special convenience.
+
+By and by the Indian hunter comes to follow the wild game. He, too,
+takes the easiest trail, the path of least resistance; and he follows
+the track to the spring that the deer have made, and he drinks there.
+He is an animal as they are, and he satisfies his animal wants
+according to the same law that governs them.
+
+After generations of hunters, Indians, and then white men, there comes
+a man on horseback looking for a house to live in. He, too, follows
+along the easiest paths and stops at the spring; and near by he finds
+the place he is looking for. Soon he returns, driving before him herds
+of cattle and flocks of sheep, which spread over the grassy glades to
+feed. But everywhere they take the easiest place, the old paths, from
+the shady tree to the flowing spring. After awhile the hillside is
+plainly marked with these sheep trails. You can see them now whenever
+you go into the country, on every hillside.
+
+Soon there are neighbors who build their homes in the next valley, and
+a good path must be made between the different houses.
+
+A few days' work spent in moving the largest stones, in cutting down
+trees, and in levelling off a few steep slopes, makes a trail along
+which you can gallop your horse.
+
+Things move fast now,--history begins to be made quickly as soon as
+man takes a hand in it. Soon the trail is not enough: it must be
+widened so that a wagon-load of boards for a new house can be carried
+in (for the settler has found a wife). After the first cart-track is
+made to carry the boards and shingles in, a better road will be needed
+to haul firewood and grain out (for the wants of the new family have
+increased, and things must be bought in the neighboring village with
+money, and money can only be had by selling the products of the farm).
+By and by the neighborhood is so well inhabited that it is to the
+advantage of the villages all around it to have good and safe and easy
+roads there; and the road is declared a public one, and it is
+regularly kept in repair and improved at the public expense. Do not
+forget the squirrels of long ago. They were the projectors of this
+road. Their successors use it now,--men and squirrels alike,--and stop
+at the spring to drink, and under the huge oaks to rest.
+
+A few years more, and it becomes to the advantage of all to have a
+railway through the valley and over the hillside. Then a young
+surveyor, just graduated from college, comes with his chain-men and
+flag-men, and finds that the squirrels, and bears, and hunters, and
+all the rest have picked out the easiest way for him long centuries
+ago. He makes his map, and soon the chief enigneer and the president
+of the road drive along in a buggy with a pair of fast horses
+(frightening the little squirrels off their road-way and into their
+holes), and the route of the Bear Valley and Quercus Railway is
+finally selected, and here it is. See! there comes a train along the
+track. This is the way a railway route grew out of a squirrel path.
+There are thousands of little steps, but you can trace them, or
+imagine them, as well as I can tell you.
+
+It is the same all over the world. Stanley cut a track through the
+endless African forests. But it lay between the Pygmy villages, along
+the paths they had made, and through the glades where they fought
+their battles with the storks.
+
+Sometimes the first road is a river--the track is already cut. Try to
+find out where the settlements in America were in the very early
+days--before 1800. You will find them along the Hudson, the Juanita,
+the St. Lawrence, the James, the Mississippi Rivers. But when these
+are left, men follow the squirrel-tracks and bear-tracks, or the
+paths of hunters, or the roads of Roman soldiers. It is a standing
+puzzle to little children why all the great rivers flow past the great
+towns. (Why do they?) The answer to that question will tell you why
+the great battles are fought in the same regions; why Egypt has been
+the coveted prize of a dozen different conquerors (it is the gateway
+of the East); why our Civil War turned on the possession of the
+Mississippi River. It is the roadways we fight for, the ways in and
+out, whether they be land or water. Of course, we really fought for
+something better than the mere possession of a roadway, but to get
+what we fought for we had to have the roadway first.
+
+The great principle at the bottom of everything in Nature is that the
+fittest survives: or, as I think it is better to say it, in any
+particular conflict or struggle that thing survives which is the
+fittest to survive _in this particular struggle_. This is Mr. Darwin's
+discovery,--or one of them,--and the struggle for existence is a part
+of the great struggle of the whole universe, and the laws of it make
+up the methods of Evolution--of Development.
+
+It is clear now, is it not, how the railway route is the direct
+descendant of the tiny squirrel track between two oaks? The process of
+development we call Evolution, and you can trace it all around you.
+Why are your skates shaped in a certain way? Why is your gun rifled?
+Why have soldiers two sets of (now) useless buttons on the skirts of
+their coats? (I will give you three guesses for this, and the hint
+that you must think of cavalry soldiers.) Why are eagles' wings of
+just the size that they are? These and millions of like questions are
+to be answered by referring to the principle of development.
+
+Sometimes it is hard to find the clew. Sometimes the development has
+gone so far, and the final product has become so complex and special,
+that it takes a good deal of thinking to find out the real reasons.
+But they _can_ be found, whether they relate to a fashion, to one of
+the laws of our country, or to the colors on a butterfly's wing.
+
+There is a little piece of verse intended to be comic, which, on the
+contrary, is really serious and philosophical, if you understand it.
+Learn it by heart, and apply it to all kinds and conditions of things,
+and see if it does not help you to explain them to yourself....
+
+  "And Man grew a thumb for that he had need of it,
+  And developed capacities for prey.
+  For the fastest men caught the most animals,
+  And the fastest animals got away from the most men.
+  Whereby all the slow animals were eaten,
+  And all the slow men starved to death."
+
+[Illustration]
+
+
+
+
+
+HOW THE SOIL IS MADE
+
+(FROM THE FORMATION OF VEGETABLE MOULD.)
+
+BY CHARLES DARWIN.
+
+
+[Illustration: W]
+
+Worms have played a more important part in the history of the world
+than most persons would at first suppose. In almost all humid
+countries they are extraordinarily numerous, and for their size
+possess great muscular power. In many parts of England a weight of
+more than ten tons (10,516 kilogrammes) of dry earth annually passes
+through their bodies and is brought to the surface on each acre of
+land; so that the whole superficial bed of vegetable mould passes
+through their bodies in the course of every few years. From the
+collapsing of the old burrows the mould is in constant though slow
+movement, and the particles composing it are thus rubbed together. By
+these means fresh surfaces are continually exposed to the action of
+the carbonic acid in the soil, and of the humus-acids which appear to
+be still more efficient in the decomposition of rocks. The generation
+of the humus-acids is probably hastened during the digestion of the
+many half-decayed leaves which worms consume. Thus the particles of
+earth, forming the superficial mould, are subjected to conditions
+eminently favorable for their decomposition and disintegration.
+Moreover, the particles of the softer rocks suffer some amount of
+mechanical trituration in the muscular gizzards of worms, in which
+small stones serve as mill-stones.
+
+[Illustration: DIAGRAM OF THE ALIMENTARY CANAL OF AN EARTH-WORM.]
+
+The finely levigated castings, when brought to the surface in a moist
+condition, flow during rainy weather down any moderate slope; and the
+smaller particles are washed far down even a gently inclined surface.
+Castings when dry often crumble into small pellets and these are apt
+to roll down any sloping surface. Where the land is quite level and is
+covered with herbage, and where the climate is humid so that much dust
+cannot be blown away, it appears at first sight impossible that there
+should be any appreciable amount of sub-aerial denudation; but worm
+castings are blown, especially while moist and viscid, in one uniform
+direction by the prevalent winds which are accompanied by rain. By
+these several means the superficial mould is prevented from
+accumulating to a great thickness; and a thick bed of mould checks in
+many ways the disintegration of the underlying rocks and fragments of
+rock.
+
+[Illustration: A WORM CASTING, FROM NICE. (Natural Size.)]
+
+The removal of worm-castings by the above means leads to results which
+are far from insignificant. It has been shown that a layer of earth,.2
+of an inch in thickness, is in many places annually brought to the
+surface per acre; and if a small part of this amount flows, or rolls,
+or is washed, even for a short distance, down every inclined surface,
+or is repeatedly blown in one direction, a great effect will be
+produced in the course of ages. It was found by measurements and
+calculations that on a surface with a mean inclination of 9 deg. 26', 2.4
+cubic inches of earth which had been ejected by worms crossed, in the
+course of a year, a horizontal line one yard in length; so that two
+hundred and forty cubic inches would cross a line one hundred yards in
+length. This latter amount in a damp state would weigh eleven and
+one-half pounds. Thus, a considerable weight of earth is continually
+moving down each side of every valley, and will in time reach its bed.
+Finally, this earth will be transported by the streams flowing in the
+valleys into the ocean, the great receptacle for all matter denuded
+from the land. It is known from the amount of sediment annually
+delivered into the sea by the Mississippi, that its enormous
+drainage-area must on an average be lowered.00263 of an inch each
+year; and this would suffice in four and a half million years to lower
+the whole drainage-area to the level of the seashore. So that if a
+small fraction of the layer of fine earth,.2 of an inch in thickness,
+which is annually brought to the surface by worms, is carried away, a
+great result cannot fail to be produced within a period which no
+geologist considers extremely long.
+
+[Illustration: SECTION THROUGH ONE OF THE DRUIDICAL STONES AT
+STONEHENGE, SHOWING HOW MUCH IT HAD SUNK INTO THE GROUND.
+
+(Scale, 1/2 inch to 1 foot.)]
+
+Archaeologists ought to be grateful to worms, as they protect and
+preserve for an indefinitely long period every object, not liable to
+decay, which is dropped on the surface of the land, by burying it
+beneath their castings. Thus, also, many elegant and curious
+tesselated pavements and other ancient remains have been preserved;
+though no doubt the worms have in these cases been largely aided by
+earth washed and blown from the adjoining land, especially when
+cultivated. The old tesselated pavements have, however, often suffered
+by having subsided unequally from being unequally undermined by the
+worms. Even old massive walls may be undermined and subside; and no
+building is in this respect safe, unless the foundations lie six or
+seven feet beneath the surface, at a depth at which worms cannot work.
+It is probable that many monoliths and some old walls have fallen
+down from having been undermined by worms.
+
+Worms prepare the ground in an excellent manner for the growth of
+fibrous-rooted plants and for seedlings of all kinds. They
+periodically expose the mould to the air, and sift it so that no
+stones larger than the particles which they can swallow are left in
+it. They mingle the whole intimately together, like a gardener who
+prepares fine soil for his choicest plants. In this state it is well
+fitted to retain moisture and to absorb all soluble substances, as
+well as for the process of nitrification. The bones of dead animals,
+the harder parts of insects, the shells of land mollusks, leaves,
+twigs, etc., are before long all buried beneath the accumulated
+castings of worms, and are thus brought in a more or less decayed
+state within reach of the roots of plants. Worms likewise drag an
+infinite number of dead leaves and other parts of plants into their
+burrows, partly for the sake of plugging them up and partly as food.
+
+The leaves which are dragged into the burrows as food, after being
+torn into the finest shreds, partially digested and saturated with the
+intestinal and urinary secretions, are commingled with much earth.
+This earth forms the dark-colored, rich humus which almost everywhere
+covers the surface of the land with a fairly well-defined layer or
+mantle. Von Hensen placed two worms in a vessel eighteen inches in
+diameter, which was filled with sand, on which fallen leaves were
+strewed; and these were soon dragged into their burrows to a depth of
+three inches. After about six weeks an almost uniform layer of sand, a
+centimetre (.4 inch) in thickness, was converted into humus by having
+passed through the alimentary canals of these two worms. It is
+believed by some persons that worm-burrows, which often penetrate the
+ground almost perpendicularly to a depth of five or six feet,
+materially aid in its drainage; notwithstanding that the viscid
+castings piled over the mouths of the burrows prevent or check the
+rain-water directly entering them. They allow the air to penetrate
+deeply into the ground. They also greatly facilitate the downward
+passage of roots of moderate size; and these will be nourished by the
+humus with which the burrows are lined. Many seeds owe their
+germination to having been covered by castings; and others buried to a
+considerable depth beneath accumulated castings lie dormant, until at
+some future time they are accidentally uncovered and germinate.
+
+[Illustration: A WORM CASTING FROM SOUTH INDIA. (Natural Size.)]
+
+Worms are poorly provided with sense-organs, for they cannot be said
+to see, although they can just distinguish between light and darkness;
+they are completely deaf, and have only a feeble power of smell; the
+sense of touch alone is well developed. They can, therefore, learn
+little about the outside world, and it is surprising that they should
+exhibit some skill in lining their burrows with their castings and
+with leaves, and in the case of some species in piling up their
+castings into tower-like constructions. But it is far more surprising
+that they should apparently exhibit some degree of intelligence
+instead of a mere blind, instinctive impulse, in their manner of
+plugging up the mouths of their burrows. They act in nearly the same
+manner as would a man, who had to close a cylindrical tube with
+different kinds of leaves, petioles, triangles of paper, etc., for
+they commonly seize such objects by their pointed ends. But with thin
+objects a certain number are drawn in by their broader ends. They do
+not act in the same unvarying manner in all cases, as do most of the
+lower animals; for instance, they do not drag in leaves by their
+foot-stalks, unless the basil part of the blade is as narrow as the
+apex, or narrower than it.
+
+       *       *       *       *       *
+
+When we behold a wide, turf-covered expanse, we should remember that
+its smoothness, on which so much of its beauty depends, is mainly due
+to all the inequalities having been slowly levelled by worms. It is a
+marvellous reflection that the whole of the superficial mould over any
+such expanse has passed, and will again pass, every few years through
+the bodies of worms. The plough is one of the most ancient and most
+valuable of man's inventions; but long before he existed the land was
+in fact regularly ploughed, and, still continues to be thus ploughed
+by earth-worms. It may be doubted whether there are many other animals
+which have played so important a part in the history of the world, as
+have these lowly organized creatures. Some other animals, however,
+still more lowly organized, namely, corals, have done far more
+conspicuous work in having constructed innumerable reefs and islands
+in the great oceans; but these are almost confined to the tropical
+zones.
+
+[Illustration]
+
+
+
+
+ZOOeLOGICAL MYTHS
+
+(FROM FACTS AND FICTIONS OF ZOOeLOGY.)
+
+BY ANDREW WILSON.
+
+
+[Illustration]
+
+When the country swain, loitering along some lane, comes to a
+standstill to contemplate, with awe and wonder, the spectacle of a
+mass of the familiar "hair-eels" or "hair-worms" wriggling about in a
+pool, he plods on his way firmly convinced that, as he has been taught
+to believe, he has just witnessed the results of the transformation of
+some horse's hairs into living creatures. So familiar is this belief
+to people of professedly higher culture than the countryman, that the
+transformation just alluded to has to all, save a few thinking persons
+and zooelogists, become a matter of the most commonplace kind. When
+some quarrymen, engaged in splitting up the rocks, have succeeded in
+dislodging some huge mass of stone, there may sometimes be seen to hop
+from among the debris a lively toad or frog, which comes to be
+regarded by the excavators with feelings akin to those of
+superstitious wonder and amazement. The animal may or may not be
+captured; but the fact is duly chronicled in the local newspapers, and
+people wonder for a season over the phenomenon of a veritable Rip Van
+Winkle of a frog, which to all appearance, has lived for "thousands of
+years in the solid rock." Nor do the hair-worm and the frog stand
+alone in respect of their marvellous origin. Popular zooelogy is full
+of such marvels. We find unicorns, mermaids, and mermen; geese
+developed from the shell-fish known as "barnacles"; we are told that
+crocodiles may weep, and that sirens can sing--in short, there is
+nothing so wonderful to be told of animals that people will not
+believe the tale. Whilst, curiously enough, when they are told of
+veritable facts of animal life, heads begin to shake and doubts to be
+expressed, until the zooelogist despairs of educating people into
+distinguishing fact from fiction, and truth from theories and
+unsupported beliefs. The story told of the old lady, whose youthful
+acquaintance of seafaring habits entertained her with tales of the
+wonders he had seen, finds, after all, a close application in the
+world at large. The dame listened with delight, appreciation, and
+belief, to accounts of mountains of sugar and rivers of rum, and to
+tales of lands where gold and silver and precious stones were more
+than plentiful. But when the narrator descended to tell of fishes that
+were able to raise themselves out of the water in flight, the old
+lady's credulity began to fancy itself imposed upon; for she
+indignantly repressed what she considered the lad's tendency to
+exaggeration, saying, "Sugar mountains may be, and rivers of rum may
+be, but fish that flee ne'er can be!" Many popular beliefs concerning
+animals partake of the character of the old lady's opinions regarding
+the real and fabulous; and the circumstance tells powerfully in favor
+of the opinion that a knowledge of our surroundings in the world, and
+an intelligent conception of animal and plant life, should form part
+of the school-training of every boy and girl, as the most effective
+antidote to superstitions and myths of every kind.
+
+
+[Illustration: FLYING FISH.]
+
+The tracing of myths and fables is a very interesting task, and it
+may, therefore, form a curious study, if we endeavor to investigate
+very briefly a few of the popular and erroneous beliefs regarding
+lower animals. The belief regarding the origin of the hair-worms is
+both widely spread and ancient. Shakespeare tells us that
+
+                                  "Much, is breeding
+  Which, like the courser's hair, hath, yet but life,
+  And not a serpent's poison."
+
+The hair-worms certainly present the appearance of long, delicate
+black hairs, which move about with great activity amidst the mud of
+pools and ditches. These worms, in the early stages of their
+existence, inhabit the bodies of insects, and may be found coiled up
+within the grasshopper, which thus gives shelter to a guest exceeding
+many times the length of the body of its host. Sooner or later the
+hair-worm, or _Gordius aquaticus_ as the naturalist terms it, leaves
+the body of the insect, and lays its eggs, fastened together in long
+strings, in water. From each egg a little creature armed with minute
+hooks is produced, and this young hair-worm burrows its way into the
+body of some insect, there to repeat the history of its parent. Such
+is the well-ascertained history of the hair-worm, excluding entirely
+the popular belief in its origin. There certainly does exist in
+science a theory known as that of "spontaneous generation," which, in
+ancient times, accounted for the production of insects and other
+animals by assuming that they were produced in some mysterious fashion
+out of lifeless matter. But not even the most ardent believer in the
+extreme modification of this theory which holds a place in modern
+scientific belief, would venture to maintain the production of a
+hair-worm by the mysterious vivification of an inert substance such as
+a horse's hair.
+
+The expression "crocodile's tears" has passed into common use, and it
+therefore may be worth while noting the probable origin of this myth.
+Shakespeare, with that wide extent of knowledge which enabled him to
+draw similes from every department of human thought, says that
+
+                          "Gloster's show
+  Beguiles him, as the mournful crocodile
+  With sorrow snares relenting passengers."
+
+The poet thus indicates the belief that not only do crocodiles shed
+tears, but that sympathizing passengers, turning to commiserate the
+reptile's woes, are seized and destroyed by the treacherous creatures.
+That quaint and credulous old author--the earliest writer of English
+prose--Sir John Mandeville, in his "Voiage," or account of his
+"Travile," published about 1356--in which, by the way, there are to be
+found accounts of not a few wonderful things in the way of zooelogical
+curiosities--tells us that in a certain "contre and be all yonde, ben
+great plenty of Crokodilles, that is, a manner of a long Serpent as I
+have seyed before." He further remarks that "these Serpents slew men,"
+and devoured them, weeping; and he tells us, too, that "whan thei
+eaten thei meven (move) the over jowe (upper jaw), and nought the
+nether (lower) jowe: and thei have no tonge (tongue)." Sir John thus
+states two popular beliefs of his time and of days prior to his age,
+namely, that crocodiles move their upper jaws, and that a tongue was
+absent in these animals.
+
+[Illustration: CROCODILE.]
+
+As regards the tears of the crocodile, no foundation of fact exists
+for the belief in such sympathetic exhibitions. But a highly probable
+explanation may be given of the manner in which such a belief
+originated. These reptiles unquestionably emit very loud and
+singularly plaintive cries, compared by some travellers to the
+mournful howling of dogs. The earlier and credulous travellers would
+very naturally associate tears with these cries, and, once begun, the
+supposition would be readily propagated, for error and myth are ever
+plants of quick growth. The belief in the movement of the upper jaw
+rests on apparent basis of fact. The lower jaw is joined to the skull
+very far back on the latter, and the mouth-opening thus comes to be
+singularly wide; whilst, when the mouth opens, the skull and upper jaw
+are apparently observed to move. This is not the case, however; the
+apparent movement arising from the manner in which the lower jaw and
+the skull are joined together. The belief in the absence of the tongue
+is even more readily explained. When the mouth is widely opened, no
+tongue is to be seen. This organ is not only present, but is,
+moreover, of large size; it is, however, firmly attached to the floor
+of the mouth, and is specially adapted, from its peculiar form and
+structure, to assist these animals in the capture and swallowing of
+their prey.
+
+One of the most curious fables regarding animals which can well be
+mentioned, is that respecting the so-called "Bernicle" or "Barnacle
+Geese," which by the naturalists and educated persons of the Middle
+Ages were believed to be produced by those little Crustaceans named
+"Barnacles." With the "Barnacles" every one must be familiar who has
+examined the floating driftwood of the sea-beach, or who has seen
+ships docked in a seaport town. A barnacle is simply a kind of crab
+enclosed in a triangular shell, and attached by a fleshy stalk to
+fixed objects. If the barnacle is not familiar to readers, certain
+near relations of these animals must be well known, by sight at least,
+as amongst the most familiar denizens of our sea-coast. These latter
+are the "Sea-Acorn," or Balani, whose little conical shells we crush
+by hundreds as we walk over the rocks at low-water mark; whilst every
+wooden pile immersed in the sea becomes coated in a short time with a
+thick crust of the "Sea-Acorns." If we place one of these little
+animals, barnacle, or sea-acorn--the latter wanting the stalk of the
+former--in its native waters, we shall observe a beautiful little
+series of feathery plumes to wave backward and forward, and ever and
+anon to be quickly withdrawn into the secure recesses of the shell.
+These organs are the modified feet of the animal, which not only serve
+for sweeping food-particles into the mouth, but act also as
+breathing-organs. We may, therefore, find it a curious study to
+inquire through what extraordinary transformation and confusion of
+ideas such an animal could be credited with giving origin to a
+veritable goose; and the investigation of the subject will also afford
+a singularly apt illustration of the ready manner in which the fable
+of one year or period becomes transmitted and transformed into the
+secure and firm belief of the next.
+
+We may begin our investigation by inquiring into some of the opinions
+which were entertained on this subject and ventilated by certain old
+writers. Between 1154 and 1189 Giraldus Cambrensis, in a work entitled
+"Topographia Hiberniae," written in Latin, remarks concerning "many
+birds which are called Bernacae: against nature, nature produces them
+in a most extraordinary way. They are like marsh geese, but somewhat
+smaller. They are produced from fir timber tossed along the sea, and
+are at first like gum. Afterward they hang down by their beaks, as if
+from a seaweed attached to the timber, surrounded by shells, in order
+to grow more freely," Giraldus is here evidently describing the
+barnacles themselves. He continues: "Having thus, in process of time,
+been clothed with a strong coat of feathers, they either fall into the
+water or fly freely away into the air. They derive their food and
+growth from the sap of the wood or the sea, by a secret and most
+wonderful process of alimentation. I have frequently, with my own
+eyes, seen more than a thousand of these small bodies of birds,
+hanging down on the seashore from one piece of timber, enclosed in
+shells, and already formed." Here, again, our author is speaking of
+the barnacles themselves, with which he naturally confuses the geese,
+since he presumes the Crustaceans are simply geese in an undeveloped
+state. He further informs his readers that, owing to their presumably
+marine origin, "bishops and clergymen in some parts of Ireland do not
+scruple to dine off these birds at the time of fasting, because they
+are not flesh, nor born of flesh," although for certain other and
+theological reasons, not specially requiring to be discussed in the
+present instance, Giraldus disputes the legality of this practice of
+the Hibernian clerics.
+
+In the year 1527 appeared "The Hystory and Croniclis of Scotland, with
+the cosmography and dyscription thairof, compilit be the noble Clerk
+Maister Hector Boece, Channon of Aberdene." Boece's "History" was
+written in Latin; the title we have just quoted being that of the
+English version of the work (1540), which title further sets forth
+that Boece's work was "Translait laitly in our vulgar and commoun
+langage be Maister Johne Bellenden, Archedene of Murray, And
+Imprentit in Edinburgh, be me Thomas Davidson, prenter to the Kyngis
+nobyll grace." In this learned work the author discredits the popular
+ideas regarding the origin of the geese. "Some men belevis that thir
+clakis (geese) growis on treis be the nebbis (bills). Bot thair
+opinoun is vane. And becaus the nature and procreatioun of thir clakis
+is strange, we have maid na lytyll laboure and deligence to serche ye
+treuth and verite yairof, we have salit (sailed) throw ye seis quhare
+thir clakis ar bred, and I fynd be gret experience, that the nature of
+the seis is mair relevant caus of thair procreatioun than ony uthir
+thyng." According to Boece, then, "the nature of the seis" formed the
+chief element in the production of the geese, and our author proceeds
+to relate how "all treis (trees) that ar casein in the seis be proces
+of tyme apperis first wormeetin (worm-eaten), and in the small boris
+and hollis (holes) thairof growis small worms." Our author no doubt
+here alludes to the ravages of the Teredo, or ship-worm, which burrows
+into timber, and with which the barnacles themselves are thus
+confused. Then he continues, the "wormis" first "schaw (show) thair
+heid and feit, and last of all thay schaw thair plumis and wyngis.
+Finaly, quhen thay ar cumyn to the just mesure and quantite of geis,
+thay fle in the aire as othir fowlis dois, as was notably provyn, in
+the yeir of God ane thousand iii hundred lxxxx, in sicht of mony
+pepyll, besyde the castell of Petslego." On the occasion referred to,
+Boece tells us that a great tree was cast on shore, and was divided,
+by order of the "laird" of the ground, by means of a saw. Wonderful to
+relate, the tree was found not merely to be riddled with a "multitude
+of wormis," throwing themselves out of the holes of the tree, but some
+of the "wormis" had "baith heid, feit, and wyngis," but, adds the
+author, "they had no fedderis (feathers)."
+
+Unquestionably, either "the scientific use of the imagination" had
+operated in this instance in inducing the observers to believe that in
+this tree, riddled by the ship-worms and possibly having barnacles
+attached to it, they beheld young geese; or Boece had construed the
+appearances described as those representing the embryo stages of the
+barnacle geese.
+
+Boece further relates how a ship named the Christofir was brought to
+Leith, and was broken down because her timbers had grown old and
+failing. In these timbers were beheld the same "wormeetin"
+appearances, "all the hollis thairof" being "full of geis." Boece
+again most emphatically rejects the idea that the "geis" were produced
+from the wood of which the timbers were composed, and once more
+proclaims his belief that the "nature of the seis resolvit in geis"
+may be accepted as the true and final explanation of their origin. A
+certain "Maister Alexander Galloway" had apparently strolled with the
+historian along the sea-coast, the former giving "his mynd with maist
+ernist besynes to serche the verite of this obscure and mysty dowtis."
+Lifting up a piece of tangle, they beheld the seaweed to be hanging
+full of mussel-shells from the root to the branches. Maister Galloway
+opened one of the mussel-shells, and was "mair astonis than afore" to
+find no fish therein, but a perfectly shaped "foule, smal and gret,"
+as corresponded to the "quantity of the shell." And once again Boece
+draws the inference that the trees or wood on which the creatures are
+found have nothing to do with the origin of the birds; and that the
+fowls are begotten of the "occeane see, quhilk," concludes our author,
+"is the caus and production of mony wonderful thingis."
+
+More than fifty years after the publication of Boece's "History," old
+Gerard of London, the famous "master in chirurgerie" of his day, gave
+an account of the barnacle goose, and not only entered into minute
+particulars of its growth and origin, but illustrated its manner of
+production by means of the engraver's art of his day. Gerard's
+"Herball," published in 1597, thus contains, amongst much that is
+curious in medical lore, a very quaint piece of zooelogical history. He
+tells us that "in the north parts of Scotland, and the Hands adjacent,
+called Orchades (Orkneys)," are found "certaine trees, whereon doe
+growe certaine shell fishes, of a white colour tending to russet;
+wherein are conteined little living creatures: which shels in time of
+maturitie doe open, and out of them grow those little living foules
+whom we call Barnakles, in the north of England Brant Geese, and in
+Lancashire tree Geese; but the other that do fall upon the land,
+perish, and come to nothing: thus much by the writings of others, and
+also from the mouths of people of those parts, which may," concludes
+Gerard, "very well accord with truth."
+
+Not content with hearsay evidence, however, Gerard relates what his
+eyes saw and hands touched. He describes how on the coasts of a
+certain "small Hand in Lancashire called Pile of Foulders" (probably
+Peel Island), the wreckage of ships is cast up by the waves, along
+with the trunks and branches "of old and rotten trees." On these
+wooden rejectamenta "a certaine spume or froth" grows, according to
+Gerard. This spume "in time breedeth unto certaine shels, in shape
+like those of the muskle, but sharper pointed, and of a whitish
+color." This description, it may be remarked, clearly applies to the
+barnacles themselves. Gerard then continues to point out how, when the
+shell is perfectly formed, it "gapeth open, and the first thing that
+appeereth is the foresaid lace or string"--the substance described by
+Gerard as contained within the shell--"next come the legs of the Birde
+hanging out; and as it groweth greater, it openeth the shell by
+degrees, till at length it is all come forth, and hangeth only by the
+bill; in short space after it commeth to full maturitie, and falleth
+into the sea, where it gathereth feathers, and groweth to a foule,
+bigger than a Mallard, and lesser than a Goose, having blacke legs and
+bill or beake, and feathers blacke and white ... which the people of
+Lancashire call by no other name than a tree Goose."
+
+[Illustration: FIG. 1. THE BARNACLE TREE. (From Gerard's "Herball.")]
+
+Accompanying this description is the engraving of the barnicle tree
+(Fig. 1) bearing its geese progeny. From the open shells in two cases,
+the little geese are seen protruding, whilst several of the
+fully-fledged fowls are disporting themselves in the sea below.
+Gerard's concluding piece of information, with its exordium, must not
+be omitted. "They spawne," says the wise apothecary, "as it were, in
+March or Aprill; the Geese are found in Maie or June, and come to
+fulnesse of feathers in the moneth after. And thus hauing, through
+God's assistance, discoursed somewhat at large of Grasses, Herbes,
+Shrubs, Trees, Mosses, and certaine excrescences of the earth, with
+other things moe incident to the Historic thereof, we conclude and end
+our present volume, with this woonder of England. For which God's name
+be euer honored and praised." It is to be remarked that Gerard's
+description of the goose-progeny of the barnacle tree exactly
+corresponds with the appearance of the bird known to ornithologists as
+the "barnacle-goose"; and there can be no doubt that, skilled as was
+this author in the natural history lore of his day, there was no other
+feeling in his mind than that of firm belief in and pious wonder at
+the curious relations between the shells and their fowl-offspring.
+Gerard thus attributes the origin of the latter to the barnacles. He
+says nothing of the "wormeetin" holes and burrows so frequently
+mentioned by Boece, nor would he have agreed with the latter in
+crediting the "nature of the occeane see" with their production, save
+in so far as their barnacle-parents lived and existed in the waters of
+the ocean.
+
+The last account of this curious fable which we may allude to in the
+present instance is that of Sir Robert Moray, who, in his work
+entitled "A Relation concerning Barnacles," published in the
+_Philosophical Transactions_ of the Royal Society in 1677-78, gives a
+succinct account of these crustaceans and their bird-progeny. Sir
+Robert is described as "lately one of his Majesties Council for the
+Kingdom of Scotland," and we may therefore justly assume his account
+to represent that of a cultured, observant person of his day and
+generation. The account begins by remarking that the "most ordinary
+trees" found in the western islands of Scotland "are Firr and Ash."
+"Being," continues Sir Robert, "in the Island of East (Uist), I saw
+lying upon the shore a cut of a large Firr tree of about 2-1/2 foot
+diameter, and 9 or 10 foot long; which had lain so long out of the
+water that it was very dry: And most of the shells that had formerly
+cover'd it, were worn or rubb'd off. Only on the parts that lay next
+the ground, there still hung multitudes of little Shells; having
+within them little Birds, perfectly shap'd, supposed to be Barnacles."
+Here again the description applies to the barnacles; the "little
+birds" they are described as containing being of course the bodies of
+the shell-fish.
+
+"The Shells," continues the narrator, "hang at the Tree by a Neck
+longer than the Shell;" this "neck" being represented by the stalk of
+the barnacle. The neck is described as being composed "of a kind of
+filmy substance, round, and hollow, and creased, not unlike the
+Wind-pipe of a Chicken; spreading out broadest where it is fastened to
+the Tree, from which it seems to draw and convey the matter which
+serves for the growth and vegetation of the Shell and the little Bird
+within it." Sir Robert Moray therefore agrees in respect of the manner
+of nourishment of the barnacles with the opinion of Giraldus already
+quoted. The author goes on to describe the "Bird" found in every
+shell he opened; remarking that "there appeared nothing wanting as to
+the internal parts, for making up a perfect Sea-fowl: every little
+part appearing so distinctly, that the whole looked like a large Bird
+seen through a concave or diminishing Glass, colour and feature being
+everywhere so clear and neat." The "Bird" is most minutely described
+as to its bill, eyes, head, neck, breast, wings, tail, and feet, the
+feathers being "everywhere perfectly shaped, and blackish-coloured.
+All being dead and dry," says Sir Robert, "I did not look after the
+Internal parts of them," a statement decidedly inconsistent with his
+previous assertion as to the perfect condition of the "internal
+parts"; and he takes care to add, "nor did I ever see any of the
+little Birds alive, nor met with anybody that did. Only some credible
+persons," he concludes, "have assured me they have seen some as big as
+their fist."
+
+[Illustration: FIG. 2. BARNACLE TREE. (From Munster's "Cosmography.")]
+
+This last writer thus avers that he saw little birds within the shells
+he clearly enough describes as those of the barnacles. We must either
+credit Sir Robert with describing what he never saw, or with
+misconstruing what he did see. His description of the goose
+corresponds with that of the barnacle goose, the reputed progeny of
+the shells; and it would, therefore, seem that this author, with the
+myth at hand, saw the barnacles only with the eyes of a credulous
+observer, and thus beheld, in the inside of each shell--if, indeed,
+his research actually extended thus far--the reproduction in miniature
+of a goose, with which, as a mature bird, he was well acquainted.
+
+On p. 157 is a woodcut, copied from Munster's "Cosmography" (1550), a
+very popular book in its time, showing the tree with its fruit, and
+the geese which are supposed to have just escaped from it.
+
+This historical ramble may fitly preface what we have to say regarding
+the probable origin of the myth. By what means could the barnacles
+become credited with the power of producing the well-known geese? Once
+started, the progress and growth of the myth are easily accounted for.
+The mere transmission of a fable from one generation or century to
+another is a simply explained circumstance, and one exemplified by the
+practices of our own times. The process of accretion and addition is
+also well illustrated in the perpetuation of fables; since the tale is
+certain to lose nothing in its historical journey, but, on the
+contrary, to receive additional elaboration with increasing age.
+Professor Max Mueller, after discussing various theories of the origin
+of the barnacle myth, declares in favor of the idea that confusion of
+language and alteration of names lie at the root of the error. The
+learned author of the "Science of Language" argues that the true
+barnacles were named, properly enough, Bernaculae, and lays stress on
+the fact that Bernicle geese were first caught in Ireland. That
+country becomes _Hibernia_ in Latin, and the Irish geese were
+accordingly named Hibernicae, or Hiberniculae. By the omission of the
+first syllable--no uncommon operation for words to undergo--we obtain
+the name Berniculae for the geese, this term being almost synonymous
+with the name Bernaculae already applied, as we have seen, to the
+barnacles. Bernicle geese and bernicle shells, confused in name, thus
+became confused in nature; and, once started, the ordinary process of
+growth was sufficient to further intensify, and render more realistic,
+the story of the bernicle tree and its wonderful progeny.
+
+By way of a companion legend to that of the barnacle tree, we may
+select the story of the "Lamb Tree" of Cathay, told by Sir John
+Mandeville, whose notes of travel regarding crocodiles' tears, and
+other points in the conformation of these reptiles, have already been
+referred to. Sir John, in that chapter of his work which treats "Of
+the Contries and Yles that ben bezonde the Lond of Cathay; and of the
+Frutes there," etc., relates that in Cathay "there growethe a manner
+of Fruyt, as thoughe it were Gowrdes: and whan thei ben rype, men
+kutten (cut) hem a to (them in two), and men fyndem with inne a
+lytylle Best (beast), in Flessche in Bon and Blode (bone and blood) as
+though it were a lytylle Lomb (lamb) with outen wolle (without wool).
+And men eaten both the Frut and the Best; and that," says Sir John,
+"is a great marveylle. Of that frut," he continues, "I have eten; alle
+thoughe it were wondirfulle"--this being added, no doubt, from an
+idea that there might possibly be some stay-at-home persons who would
+take Sir John's statement _cum grano salis_. "But," adds this worthy
+"knyght of Ingolond," "I knowe wel that God is marveyllous in His
+Werkes." Not to be behind the inhabitants of Cathay in a tale of
+wonders, the knight related to these Easterns "als gret a marveylle to
+hem that is amonges us; and that was of the Bernakes. For I tolde him
+hat in oure Countree weren Trees that beren a Fruyt, that becomen
+Briddes (birds) fleeynge: and tho that fellen in the Water lyven
+(live); and thei that fallen on the Erthe dyen anon: and thei ben
+right gode to mannes mete (man's meat). And here had thei als gret
+marvayle," concludes Sir John, "that sume of hem trowed it were an
+impossible thing to be." Probably the inhabitants of Cathay, knowing
+their own weakness as regards the lamb tree, might possess a
+fellow-feeling for their visitor's credulity, knowing well, from
+experience, the readiness with which a "gret marvayle" could be
+evolved and sustained.
+
+Passing from the sphere of the mythical and marvellous as represented
+in mediaeval times, we may shortly discuss a question, which, of all
+others, may justly claim a place in the records of Zooelogical
+curiosities--namely, the famous and oft-repeated story of the "Toad
+from the solid rock," as the country newspapers style the incident.
+Regularly, year by year, and in company with the reports of the
+sea-serpent's reappearance, we may read of the discoveries of toads
+and frogs in situations and under circumstances suggestive of a
+singular vitality on the part of the amphibians, of more than usual
+credulity on the part of the hearers, or of a large share of
+inventive genius in the narrators of such tales. The question
+possesses for every one a certain degree of interest, evoked by the
+curious and strange features presented on the face of the tales. And
+it may therefore not only prove an interesting but also a useful
+study, if we endeavor to arrive at some just and logical conceptions
+of these wonderful narrations.
+
+[Illustration]
+
+Instances of the discovery of toads and frogs in solid rocks need not
+be specially given; suffice it to say, that these narratives are
+repeated year by year with little variation. A large block of stone or
+face of rock is detached from its site, and a toad or frog is seen
+hereafter to be hopping about in its usual lively manner. The
+conclusion to which the bystanders invariably come is that the animal
+must have been contained within the rock, and that it was liberated by
+the dislodgement of the mass. Now, in many instances, cases of the
+appearance of toads during quarrying operations have been found, on
+close examination, to present no evidence whatever that the appearance
+of the animals was due to the dislodgement of the stones. A frog or
+toad may be found hopping about among some recently formed debris, and
+the animal is at once seized upon and reported as having emerged from
+the rocks into the light of day. There is in such a case not the
+slightest ground for supposing any such thing; and the animal may more
+reasonably be presumed to have simply hopped into the debris from its
+ordinary habitat. But laying aside narratives of this kind, which lose
+their plausibility under a very commonplace scrutiny, there still
+exist cases, reported in an apparently exact and truthful manner, in
+which these animals have been alleged to appear from the inner
+crevices of rocks after the removal of large masses of the formations.
+We shall assume these latter tales to contain a plain, unvarnished
+statement of what was observed, and deal with the evidence they
+present on this footing.
+
+[Illustration: A TOAD.]
+
+One or two notable examples of such verified tales are related by
+Smellie, in his "Philosophy of Natural History." Thus, in the "Memoirs
+of the French Academy of Sciences" for 1719, a toad is described as
+having been found in the heart of an elm tree; and another is stated
+to have been found in the heart of an old oak tree, in 1731, near
+Nantz. The condition of the trees is not expressly stated, nor are we
+afforded any information regarding the appearance of the
+toads--particulars of considerable importance in view of the
+suggestions and explanations to be presently brought forward. Smellie
+himself, while inclined to be sceptical in regard to the truth or
+exactness of many of the tales told of the vitality of toads, regards
+the matter as affording food for reflection, since he remarks, "But I
+mean not to persuade, for I cannot satisfy myself; all I intend is, to
+recommend to those gentlemen who may hereafter chance to see such rare
+phenomena, a strict examination of every circumstance that can throw
+light upon a subject so dark and mysterious; for the vulgar, ever
+inclined to render uncommon appearances still more marvellous, are not
+to be trusted."
+
+This author strikes the key-note of the inquiry in his concluding
+words, and we shall find that the explanation of the matter really
+lies in the clear understanding of what are the probabilities, and
+what the actual details, of the cases presented for consideration. We
+may firstly, then, glance at a few of the peculiarities of the frogs
+and toads, regarded from a zooelogical point of view. As every one
+knows, these animals emerge from the egg in the form of little
+fish-like "tadpoles," provided with outside gills, which are soon
+replaced by inside gills, resembling those of fishes. The hind legs
+are next developed, and the fore limbs follow a little later; whilst,
+with the development of lungs, and the disappearance of the gills and
+tail, the animal leaves the water, and remains for the rest of its
+life an air-breathing, terrestrial animal. Then, secondly, in the
+adult frog or toad, the naturalist would point to the importance of
+the skin as not only supplementing, but, in some cases, actually
+supplanting the work of the lungs as the breathing organ. Frogs and
+toads will live for months under water, and will survive the excision
+of the lungs for like periods; the skin in such cases serving as the
+breathing surface. A third point worthy of remembrance is included in
+the facts just related, and is implied in the information that these
+animals can exist for long periods without food, and with but a
+limited supply of air. We can understand this toleration on the part
+of these animals when we take into consideration their cold-blooded
+habits, which do not necessitate, and which are not accompanied by,
+the amount of vital activity we are accustomed to note in higher
+animals. And, as a last feature in the purely scientific history of
+the frogs and toads, it may be remarked that these animals are known
+to live for long periods. One pet toad is mentioned by a Mr. Arscott
+as having attained, to his knowledge, the age of thirty-six years; and
+a greater age still might have been recorded of this specimen, but for
+the untoward treatment it sustained at the hands, or rather beak, of a
+tame raven. In all probability it may be safely assumed that, when the
+conditions of life are favorable, these creatures may attain a highly
+venerable age--regarding the lapse of time from a purely human and
+interested point of view.
+
+We may now inquire whether or not the foregoing considerations may
+serve to throw any light upon the tales of the quarryman. The first
+point to which attention may be directed is that involved in the
+statement that the amphibian has been imprisoned in a _solid_ rock.
+Much stress is usually laid on the fact that the rock was solid; this
+fact being held to imply the great age, not to say antiquity, of the
+rock and its supposed tenant. The impartial observer, after an
+examination of the evidence presented, will be inclined to doubt
+greatly the justification for inserting the adjective "solid"; for
+usually no evidence whatever is forthcoming as to the state of the
+rock prior to its removal. No previous examination of the rock is or
+can be made, from the circumstance that no interest can possibly
+attach to its condition until its removal reveals the apparent wonder
+it contained, in the shape of the live toad. And it is equally
+important to note that we rarely, if ever, find mention of any
+examination of the rock being made subsequently to the discovery.
+Hence, a first and grave objection may be taken to the validity of the
+supposition that the rock was solid, and it may be fairly urged that
+on this supposition the whole question turns and depends. For if the
+rock cannot be proved to have been impermeable to and barred against
+the entrance of living creatures, the objector may proceed to show the
+possibility of the toad having gained admission, under certain notable
+circumstances, to its prison-house.
+
+The frog or toad in its young state, and having just entered upon its
+terrestrial life, is a small creature, which could, with the utmost
+ease, wriggle into crevices and crannies of a size which would almost
+preclude such apertures being noticed at all. Gaining access to a
+roomier crevice or nook within, and finding there a due supply of air,
+along with a dietary consisting chiefly of insects, the animal would
+grow with tolerable rapidity, and would increase to such an extent
+that egress through its aperture of entrance would become an
+impossibility. Next, let us suppose that the toleration of the toad's
+system to starvation and to a limited supply of air is taken into
+account, together with the fact that these creatures will hibernate
+during each winter, and thus economize, as it were, their vital
+activity and strength; and after the animal has thus existed for a
+year or two--no doubt under singularly hard conditions--let us imagine
+that the rock is split up by the wedge and lever of the excavator. We
+can then readily enough account for the apparently inexplicable story
+of "the toad in the rock." "There is the toad and here is the solid
+rock," say the gossips. "There is an animal which has singular powers
+of sustaining life under untoward conditions, and which, in its young
+state, could have gained admittance to the rock through a mere
+crevice," says the naturalist in reply. Doubtless, the great army of
+the unconvinced may still believe in the tale as told them; for the
+weighing of evidence and the placing _pros_ and _cons_ in fair
+contrast are not tasks of congenial or wonted kind in the ordinary run
+of life. Some people there will be who will believe in the original
+solid rock and its toad, despite the assertion of the geologists that
+the earliest fossils of toads appear in almost the last-formed rocks,
+and that a live toad in rocks of very ancient age--presuming,
+according to the popular belief, that the animal was enclosed when the
+rock was formed--would be as great an anomaly and wonder as the
+mention, as an historical fact, of an express train or the telegraph
+in the days of the patriarchs. In other words, the live toad which
+hops out of an Old Red Sandstone rock must be presumed, on the popular
+belief, to be older by untold ages than the oldest fossil frogs and
+toads. The reasonable mind, however, will ponder and consider each
+feature of the case, and will rather prefer to countenance a
+supposition based on ordinary experience, than an explanation brought
+ready-made from the domain of the miraculous; whilst not the least
+noteworthy feature of these cases is that included in the remark of
+Smellie, respecting the tendency of uneducated and superstitious
+persons to magnify what is uncommon, and in his sage conclusion that
+as a rule such persons in the matter of their relations "are not to be
+trusted."
+
+But it must also be noted that we possess valuable evidence of a
+positive and direct kind bearing on the duration of life in toads
+under adverse circumstances. As this evidence tells most powerfully
+against the supposition that the existence of those creatures can be
+indefinitely prolonged, it forms of itself a veritable court of appeal
+in the cases under discussion. The late Dr. Buckland, curious to learn
+the exact extent of the vitality of the toad, caused, in the year
+1825, two large blocks of stone to be prepared. One of the blocks was
+taken from the ooelite limestone, and in this first stone twelve cells
+were excavated. Each cell was one foot deep and five inches in
+diameter. The mouth of each cell was grooved so as to admit of two
+covers being placed over the aperture; the first or lower cover being
+of glass, and the upper one of slate. Both covers were so adapted that
+they could be firmly luted down with clay or putty; the object of this
+double protection being that the slate cover could be raised so as to
+inspect the contained object through the closed glass cover without
+admitting air. In the second or sandstone block, a series of twelve
+cells was also excavated; these latter cells being, however, of
+smaller size than those of the limestone block, each cell being only
+six inches in depth by five inches in diameter. These cells were
+likewise fitted with double covers.
+
+On November 26th, 1825, a live toad--kept for some time previously to
+insure its being healthy--was placed in each of the twenty-four cells.
+The largest specimen weighed 1185 grains, and the smallest 115 grains.
+The stones and the immured toads were buried on the day mentioned,
+three feet deep, in Dr. Buckland's garden. There they lay until
+December 10th, 1826, when they were disinterred and their tenants
+examined. All the toads in the smaller cells of the sandstone block
+were dead, and from the progress of decomposition it was inferred that
+they had succumbed long before the date of disinterment. The majority
+of the toads in the limestone block were alive, and, curiously enough,
+one or two had actually increased in weight. Thus, No. 5, which at the
+commencement of its captivity had weighed 1185 grains, had increased
+to 1265 grains; but the glass cover of No. 5's cell was found to be
+cracked. Insects and air must therefore have obtained admittance and
+have afforded nourishment to the imprisoned toad; this supposition
+being rendered the more likely by the discovery that in one of the
+cells, the covers of which were also cracked and the tenant of which
+was dead, numerous insects were found. No. 9, weighing originally 988
+grains, had increased during its incarceration to 1116 grains; but
+No. 1, which in the year 1825 had weighed 924 grains, was found in
+December, 1826, to have decreased to 698 grains; and No. 11,
+originally weighing 936 grains, had likewise disagreed with the
+imprisonment, weighing only 652 grains when examined in 1826.
+
+At the period when the blocks of stone were thus prepared, four toads
+were pinned up in holes five inches deep and three inches in diameter,
+cut in the, stem of an apple-tree; the holes being firmly plugged with
+tightly fitting wooden plugs. These four toads were found to be dead
+when examined along with the others in 1826; and of four others
+enclosed in basins made of plaster of Paris, and which were also
+buried in Dr. Buckland's garden, two were found to be dead at the end
+of a year, their comrades being alive, but looking starved and meagre.
+The toads which were found alive in the limestone block in December,
+1826, were again immured and buried, but were found to be dead,
+without leaving a single survivor, at the end of the second year of
+their imprisonment.
+
+These experiments may fairly be said to prove two points. They firstly
+show that under circumstances even of a favorable kind when compared
+with the condition popularly believed in--namely, that of being
+enclosed in a _solid_ rock--the limit of the toad's life may be
+assumed to be within two years; this period being no doubt capable of
+being extended when the animal gains a slight advantage, exemplified
+by the admission of air and insect-food. Secondly, we may reasonably
+argue that these experiments show that toads when rigorously treated,
+like other animals, become starved and meagre, and by no means
+resemble the lively, well-fed animals reported as having emerged from
+an imprisonment extending, in popular estimation, through periods of
+inconceivable duration.
+
+These tales are, in short, as devoid of actual foundation as are the
+modern beliefs in the venomous properties of the toad, or the ancient
+beliefs in the occult and mystic powers of various parts of its frame
+when used in incantations. Shakespeare, whilst attributing to the toad
+venomous qualities, has yet immortalized it in his famous simile by
+crediting it with the possession of a "precious jewel." But even in
+the latter case the animal gets but scant justice; for science strips
+it of its poetical reputation, and in this, as in other respects,
+shows it, despite fable and myth, to be zooelogically an interesting,
+but otherwise a commonplace member of the animal series.
+
+[Illustration]
+
+
+
+
+ON A PIECE OF CHALK
+
+_A LECTURE TO WORKING MEN_.
+
+(Delivered in England.)
+
+BY T.H. HUXLEY.
+
+
+[Illustration: A CHALK CLIFF.]
+
+If a well were to be sunk at our feet in the midst of the city of
+Norwich, the diggers would very soon find themselves at work in that
+white substance almost too soft to be called rock, with which we are
+all familiar as "chalk."
+
+Not only here, but over the whole county of Norfolk, the well-sinker
+might carry his shaft down many hundred feet without coming to the end
+of the chalk; and, on the sea-coast, where the waves have pared away
+the face of the land which breasts them, the scarped faces of the high
+cliffs are often wholly formed of the same material. Northward, the
+chalk may be followed as far as Yorkshire; on the south coast it
+appears abruptly in the picturesque western bays of Dorset, and breaks
+into the Needles of the Isle of Wight; while on the shores of Kent it
+supplies that long line of white cliffs to which England owes her name
+of Albion.
+
+Were the thin soil which covers it all washed away, a curved band of
+white chalk, here broader, and there narrower, might be followed
+diagonally across England from Lulworth in Dorset, to Flamborough Head
+in Yorkshire--a distance of over two hundred and eighty miles as the
+crow flies.
+
+From this band to the North Sea, on the east, and the Channel, on the
+south, the chalk is largely hidden by other deposits; but, except in
+the Weald of Kent and Sussex, it enters into the very foundation of
+all the south-eastern counties.
+
+Attaining, as it does in some places, a thickness of more than a
+thousand feet, the English chalk must be admitted to be a mass of
+considerable magnitude. Nevertheless, it covers but an insignificant
+portion of the whole area occupied by the chalk formation of the
+globe, which has precisely the same general character as ours, and is
+found in detached patches, some less, and others more extensive, than
+the English.
+
+Chalk occurs in north-west Ireland; it stretches over a large part of
+France--the chalk which underlies Paris being, in fact, a continuation
+of that of the London basin; it runs through Denmark and Central
+Europe, and extends southward to North Africa; while eastward, it
+appears in the Crimea and in Syria, and may be traced as far as the
+shores of the Sea of Aral, in Central Asia.
+
+If all the points at which true chalk occurs were circumscribed, they
+would lie within an irregular oval about three thousand miles in long
+diameter--the area of which would be as great as that of Europe, and
+would many times exceed that of the largest existing inland sea--the
+Mediterranean.
+
+Thus the chalk is no unimportant element in the masonry of the earth's
+crust, and it impresses a peculiar stamp, varying with the conditions
+to which it is exposed, on the scenery of the districts in which it
+occurs. The undulating downs and rounded coombs, covered with
+sweet-grassed turf, of our inland chalk country, have a peacefully
+domestic and mutton-suggesting prettiness, but can hardly be called
+either grand or beautiful. But on our southern coasts, the wall-sided
+cliffs, many hundred feet high, with vast needles and pinnacles
+standing out in the sea, sharp and solitary enough to serve as perches
+for the wary cormorant, confer a wonderful beauty and grandeur upon
+the chalk headlands. And in the East, chalk has its share in the
+formation of some of the most venerable of mountain ranges, such as
+the Lebanon.
+
+       *       *       *       *       *
+
+What is this wide-spread component of the surface of the earth? and
+whence did it come?
+
+You may think this no very hopeful inquiry. You may not unnaturally
+suppose that the attempt to solve such problems as these can lead to
+no result, save that of entangling the inquirer in vague speculations,
+incapable of refutation and of verification.
+
+If such were really the case, I should have selected some other
+subject than a "piece of chalk" for my discourse. But, in truth,
+after much deliberation, I have been unable to think of any topic
+which would so well enable me to lead you to see how solid is the
+foundation upon which some of the most startling conclusions of
+physical science rest.
+
+A great chapter of the history of the world is written in the chalk.
+Few passages in the history of man can be supported by such an
+overwhelming mass of direct and indirect evidence as that which
+testifies to the truth of the fragment of the history of the globe,
+which I hope to enable you to read, with your own eyes, to-night.
+
+[Illustration: MICROSCOPIC SECTION OF CHALK.
+
+(Magnified nearly 300 times.)
+
+1. Textularia. 2. Globigerina. 3. Rotalia. 4. Coccoliths.]
+
+Let me add, that few chapters of human history have a more profound
+significance for ourselves. I weigh my words well when I assert, that
+the man who should know the true history of the bit of chalk which
+every carpenter carries about in his breeches' pocket, though ignorant
+of all other history, is likely, if he will think his knowledge out to
+its ultimate results, to have a truer, and therefore a better,
+conception of this wonderful universe, and of man's relation to it,
+than the most learned student who is deep-read in the records of
+humanity and ignorant of those of nature.
+
+The language of the chalk is not hard to learn, not nearly so hard as
+Latin, if you only want to get at the broad features of the story it
+has to tell; and I propose that we now set to work to spell that story
+out together.
+
+We all know that if we "burn" chalk, the result is quicklime. Chalk,
+in fact, is a compound of carbonic acid gas and lime; and when you
+make it very hot, the carbonic acid flies away and the lime is left.
+
+By this method of procedure we see the lime, but we do not see the
+carbonic acid. If, on the other hand, you were to powder a little
+chalk and drop it into a good deal of strong vinegar, there would be a
+great bubbling and fizzing, and, finally, a clear liquid, in which no
+sign of chalk would appear. Here you see the carbonic acid in the
+bubbles; the lime, dissolved in the vinegar, vanishes from sight.
+There are a great many other ways of showing that chalk is essentially
+nothing but carbonic acid and quicklime. Chemists enunciate the result
+of all the experiments which prove this, by stating that chalk is
+almost wholly composed of "carbonate of lime."
+
+It is desirable for us to start from the knowledge of this fact,
+though it may not seem to help us very far toward what we seek. For
+carbonate of lime is a widely-spread substance, and is met with under
+very various conditions. All sorts of limestones are composed of more
+or less pure carbonate of lime. The crust which is often deposited by
+waters which have drained through limestone rocks, in the form of what
+are called stalagmites and stalactites, is carbonate of lime. Or, to
+take a more familiar example, the fur on the inside of a tea-kettle is
+carbonate of lime; and, for anything chemistry tells us to the
+contrary, the chalk might be a kind of gigantic fur upon the bottom of
+the earth-kettle, which is kept pretty hot below.
+
+Let us try another method of making the chalk tell us its own history.
+To the unassisted eye chalk looks simply like a very loose and open
+kind of stone. But it is possible to grind a slice of chalk down so
+thin that you can see through it--until it is thin enough, in fact, to
+be examined with any magnifying power that may be thought desirable. A
+thin slice of the fur of a kettle might be made in the same way. If it
+were examined microscopically, it would show itself to be a more or
+less distinctly laminated mineral substance, and nothing more.
+
+But the slice of chalk presents a totally different appearance when
+placed under the microscope. The general mass of it is made up of very
+minute granules; but, imbedded in this matrix, are innumerable bodies,
+some smaller and some larger, but, on a rough average, not more than a
+hundredth of an inch in diameter, having a well-defined shape and
+structure. A cubic inch of some specimens of chalk may contain
+hundreds of thousands of these bodies, compacted together with
+incalculable millions of the granules.
+
+[Illustration: CHALK.
+
+(Magnified nearly 100 diameters.)]
+
+The examination of a transparent slice gives a good notion of the
+manner in which the components of the chalk are arranged, and of
+their relative proportions. But, by rubbing up some chalk with a brush
+in water and then pouring off the milky fluid, so as to obtain
+sediments of different degrees of fineness, the granules and the
+minute rounded bodies may be pretty well separated from one another,
+and submitted to microscopic examination, either as opaque or as
+transparent objects. By combining the views obtained in these various
+methods, each of the rounded bodies may be proved to be a
+beautifully-constructed calcareous fabric, made up of a number of
+chambers, communicating freely with one another. The chambered bodies
+are of various forms. One of the commonest is something like a
+badly-grown raspberry, being formed of a number of nearly globular
+chambers of different sizes congregated together. It is called
+Globigerina, and some specimens of chalk consist of little else than
+Globigerinae and granules.
+
+[Illustration: GLOBIGERINA.]
+
+Let us fix our attention upon the Globigerina. It is the spoor of the
+game we are tracking. If we can learn what it is and what are the
+conditions of its existence, we shall see our way to the origin and
+past history of the chalk.
+
+A suggestion which may naturally enough present itself is, that these
+curious bodies are the result of some process of aggregation which has
+taken place in the carbonate of lime; that, just as in winter, the
+rime on our windows simulates the most delicate and elegantly
+arborescent foliage--proving that the mere mineral matter may, under
+certain conditions, assume the outward form of organic bodies--so this
+mineral substance, carbonate of lime, hidden away in the bowels of
+the earth, has taken the shape of these chambered bodies. I am not
+raising a merely fanciful and unreal objection. Very learned men, in
+former days, have even entertained the notion that all the formed
+things found in rocks are of this nature; and if no such conception is
+at present held to be admissible, it is because long and varied
+experience has now shown that mineral matter never does assume the
+form and structure we find in fossils. If anyone were to try to
+persuade you that an oyster-shell (which is also chiefly composed of
+carbonate of lime) had crystallized out of sea-water, I suppose you
+would laugh at the absurdity. Your laughter would be justified by the
+fact that all experience tends to show that oyster-shells are formed
+by the agency of oysters, and in no other way. And if there were no
+better reasons, we should be justified, on like grounds, in believing
+that Globigerina is not the product of anything but vital activity.
+
+Happily, however, better evidence in proof of the organic nature of
+the Globigerinae than that of analogy is forthcoming. It so happens
+that calcareous skeletons, exactly similar to the Globigerinae of the
+chalk, are being formed, at the present moment, by minute living
+creatures, which flourish in multitudes, literally more numerous than
+the sands of the sea-shore, over a large extent of that part of the
+earth's surface which is covered by the ocean.
+
+The history of the discovery of these living Globigerinae, and of the
+part which they play in rock-building, is singular enough. It is a
+discovery which, like others of no less scientific importance, has
+arisen, incidentally, out of work devoted to very different and
+exceedingly practical interests.
+
+When men first took to the sea, they speedily learned to look out for
+shoals and rocks; and the more the burthen of their ships increased,
+the more imperatively necessary it became for sailors to ascertain
+with precision the depth of the waters they traversed. Out of this
+necessity grew the use of the lead and sounding-line; and, ultimately,
+marine-surveying, which is the recording of the form of coasts and of
+the depth of the sea, as ascertained by the sounding-lead, upon
+charts.
+
+At the same time, it became desirable to ascertain and to indicate the
+nature of the sea-bottom, since this circumstance greatly affects its
+goodness as holding ground for anchors. Some ingenious tar, whose name
+deserves a better fate than the oblivion into which it has fallen,
+attained this object by "arming" the bottom of the lead with a lump of
+grease, to which more or less of the sand or mud, or broken shells, as
+the case might be, adhered, and was brought to the surface. But,
+however well adapted such an apparatus might be for rough nautical
+purposes, scientific accuracy could not be expected from the armed
+lead, and to remedy its defects (especially when applied to sounding
+in great depths) Lieutenant Brooke, of the American Navy, some years
+ago invented a most ingenious machine, by which a considerable portion
+of the superficial layer of the sea-bottom can be scooped out and
+brought up, from any depth to which the lead descends.
+
+In 1853, Lieutenant Brooke obtained mud from the bottom of the North
+Atlantic, between Newfoundland and the Azores, at a depth of more than
+ten thousand feet, or two miles, by the help of this sounding
+apparatus. The specimens were sent for examination to Ehrenberg of
+Berlin, and to Bailey of West Point, and those able microscopists
+found that this deep-sea mud was almost entirely composed of the
+skeletons of living organisms--the greater proportion of these being
+just like the Globigerinae already known to occur in chalk.
+
+Thus far, the work had been carried on simply in the interests of
+science, but Lieutenant Brooke's method of sounding acquired a high
+commercial value, when the enterprise of laying down the
+telegraph-cable between this country and the United States was
+undertaken. For it became a matter of immense importance to know, not
+only the depth of the sea over the whole line, along which the cable
+was to be laid, but the exact nature of the bottom, so as to guard
+against chances of cutting or fraying the strands of that costly rope.
+The Admiralty consequently ordered Captain Dayman, an old friend and
+shipmate of mine, to ascertain the depth over the whole line of the
+cable, and to bring back specimens of the bottom. In former days, such
+a command as this might have sounded very much like one of the
+impossible things which the young prince in the Fairy Tales is ordered
+to do before he can obtain the hand of the princess. However, in the
+months of June and July, 1857, my friend performed the task assigned
+to him with great expedition and precision, without, so far as I know,
+having met with any reward of that kind. The specimens of Atlantic mud
+which he procured were sent to me to be examined and reported upon.
+
+The result of all these operations is, that we know the contours and
+the nature of the surface-soil covered by the North Atlantic, for a
+distance of seventeen hundred miles from east to west, as well as we
+know that of any part of the dry land.
+
+It is a prodigious plain--one of the widest and most even plains in
+the world. If the sea were drained off, you might drive a wagon all
+the way from Valentia, on the west coast of Ireland, to Trinity Bay in
+Newfoundland. And, except upon one sharp incline about two hundred
+miles from Valentia, I am not quite sure that it would even be
+necessary to put the skid on, so gentle are the ascents and descents
+upon that long route. From Valentia the road would lie down-hill for
+about two hundred miles to the point at which the bottom is now
+covered by seventeen hundred fathoms of sea-water. Then would come the
+central plain, more than a thousand miles wide, the inequalities of
+the surface of which would be hardly perceptible, though the depth of
+water upon it now varies from ten thousand to fifteen thousand feet;
+and there are places in which Mont Blanc might be sunk without showing
+its peak above water. Beyond this, the ascent on the American side
+commences, and gradually leads, for about three hundred miles, to the
+Newfoundland shore.
+
+Almost the whole of the bottom of this central plain (which extends
+for many hundred miles in a north and south direction) is covered by a
+fine mud, which, when brought to the surface, dries into a grayish
+white friable substance. You can write with this on a black-board, if
+you are so inclined; and, to the eye, it is quite like very soft,
+grayish chalk. Examined chemically, it proves to be composed almost
+wholly of carbonate of lime; and if you make a section of it, in the
+same way as that of the piece of chalk was made, and view it with the
+microscope, it presents innumerable Globigerinae embedded in a granular
+matrix.
+
+Thus this deep-sea mud is substantially chalk. I say substantially,
+because there are a good many minor differences; but as these have no
+bearing on the question immediately before us--which is the nature of
+the Globigerinae of the chalk--it is unnecessary to speak of them.
+
+Globigerinae of every size, from the smallest to the largest, are
+associated together in the Atlantic mud, and the chambers of many are
+filled by a soft animal matter. This soft substance is, in fact, the
+remains of the creature to which the Globigerina shell, or rather
+skeleton, owes its existence--and which is an animal of the simplest
+imaginable description. It is, in fact, a mere particle of living
+jelly, without defined parts of any kind--without a mouth, nerves,
+muscles, or distinct organs, and only manifesting its vitality to
+ordinary observation by thrusting out and retracting from all parts of
+its surface long filamentous processes, which serve for arms and legs.
+Yet this amorphous particle, devoid of everything which, in the higher
+animals, we call organs, is capable of feeding, growing, and
+multiplying; of separating from the ocean the small proportion of
+carbonate of lime which is dissolved in sea-water; and of building up
+that substance into a skeleton for itself, according to a pattern
+which can be imitated by no other known agency.
+
+The notion that animals can live and flourish in the sea, at the vast
+depths from which apparently living Giobigerinae have been brought up,
+does not agree very well with our usual conceptions respecting the
+conditions of animal life; and it is not so absolutely impossible as
+it might at first sight appear to be, that the Globigerinae of the
+Atlantic sea-bottom do not live and die where they are found.
+
+[Illustration: DIATOM OOZE DREDGED FROM A DEPTH OF 1950 FEET.
+
+(Magnified nearly 300 diameters.)]
+
+As I have mentioned, the soundings from the great Atlantic plain are
+almost entirely made up of Globigerinae, with the granules which have
+been mentioned, and some few other calcareous shells; but a small
+percentage of the chalky mud--perhaps at most some five per cent of
+it--is of a different nature, and consists of shells and skeletons
+composed of silex, or pure flint. These siliceous bodies belong partly
+to the lowly vegetable organisms which are called Diatomaceae, and
+partly to the minute and extremely simple animals, termed Radiolaria.
+It is quite certain that these creatures do not live at the bottom of
+the ocean, but at its surface--where they may be obtained in
+prodigious numbers by the use of a properly constructed net. Hence it
+follows that these siliceous organisms, though they are not heavier
+than the lightest dust, must have fallen, in some cases, through
+fifteen thousand feet of water, before they reached their final
+resting-place on the ocean floor. And, considering how large a
+surface these bodies expose in proportion to their weight, it is
+probable that they occupy a great length of time in making their
+burial journey from the surface of the Atlantic to the bottom.
+
+[Illustration: RADIOLARIA. (_a._ Natural size. _b._ One-third natural
+size.)]
+
+But if the Radiolaria and Diatoms are thus rained upon the bottom of
+the sea, from the superficial layer of its waters in which they pass
+their lives, it is obviously possible that the Globigerinae may be
+similarly derived; and if they were so, it would be much more easy to
+understand how they obtain their supply of food than it is at present.
+Nevertheless, the positive and negative evidence all points the other
+way. The skeletons of the full-grown, deep-sea Globigerinae are so
+remarkably solid and heavy in proportion to their surface as to seem
+little fitted for floating; and, as a matter of fact, they are not to
+be found along with the Diatoms and Radiolaria, in the uppermost
+stratum of the open ocean.
+
+It has been observed, again, that the abundance of Globigerinae, in
+proportion to other organisms of like kind, increases with the depth
+of the sea; and that deep-water Globigerinae are larger than those
+which live in the shallower parts of the sea; and such facts negative
+the supposition that these organisms have been swept by currents from
+the shallows into the deeps of the Atlantic.
+
+It therefore seems to be hardly doubtful that these wonderful
+creatures live and die at the depths in which they are found.[1]
+
+[Footnote 1: During the cruise of H.M.S. Bull-dog, commanded by Sir
+Leopold M'Clintock, in 1860, living star-fish were brought up,
+clinging to the lowest part of the sounding-line, from a depth of 1260
+fathoms, midway between Cape Farewell, in Greenland, and the Rockall
+banks. Dr. Wallich ascertained that the sea-bottom at this point
+consisted of the ordinary Globigerina ooze, and that the stomachs of
+the star-fishes were full of Globigerinae. This discovery removes all
+objections to the existence of living Globigerinae at great depths,
+which are based upon the supposed difficulty of maintaining animal
+life under such conditions; and it throws the burden of proof upon
+those who object to the supposition that the Globigerinae live and die
+where they are found.]
+
+However, the important points for us are, that the living Globigerinae
+are exclusively marine animals, the skeletons of which abound at the
+bottom of deep seas; and that there is not a shadow of reason for
+believing that the habits of the Globigerinae of the chalk differed
+from those of the existing species. But if this be true, there is no
+escaping the conclusion that the chalk itself is the dried mud of an
+ancient deep sea.
+
+In working over the soundings collected by Captain Dayman, I was
+surprised to find that many of what I have called the "granules" of
+that mud were not, as one might have been tempted to think at first,
+the mere powder and waste of Globigerinae, but that they had a definite
+form and size. I termed these bodies "_coccoliths_" and doubted their
+organic nature. Dr. Wallich verified my observation, and added the
+interesting discovery that, not unfrequently, bodies similar to these
+"coccoliths" were aggregated together into spheroids, which he termed
+"_coccospheres_." So far as we knew, these bodies, the nature of which
+is extremely puzzling and problematical, were peculiar to the
+Atlantic soundings.
+
+But, a few years ago, Mr. Sorby, in making a careful examination of
+the chalk by means of thin sections and otherwise, observed, as
+Ehrenberg had done before him, that much of its granular basis
+possesses a definite form. Comparing these formed particles with those
+in the Atlantic soundings, he found the two to be identical; and thus
+proved that the chalk, like the soundings, contains these mysterious
+coccoliths and coccospheres. Here was a further and a most interesting
+confirmation, from internal evidence, of the essential identity of the
+chalk with modern deep-sea mud. Globigerinae, coccoliths, and
+coccospheres are found as the chief constituents of both, and testify
+to the general similarity of the conditions under which both have been
+formed.[2]
+
+[Footnote 2: I have recently traced out the development of the
+"coccoliths" from a diameter of 1/7000th of an inch up to their
+largest size (which is about 1/1600th), and no longer doubt that they
+are produced by independent organisms, which, like the Globigerinae,
+live and die at the bottom of the sea.]
+
+The evidence furnished by the hewing, facing, and superposition of the
+stones of the Pyramids, that these structures were built by men, has
+no greater weight than the evidence that the chalk was built by
+Globigerinae; and the belief that those ancient pyramid-builders were
+terrestrial and air-breathing creatures like ourselves, is not better
+based than the conviction that the chalk-makers lived in the sea.
+
+But as our belief in the building of the Pyramids by men is not only
+grounded on the internal evidence afforded by these structures, but
+gathers strength from multitudinous collateral proofs, and is clinched
+by the total absence of any reason for a contrary belief; so the
+evidence drawn from the Globigerinae that the chalk is an ancient
+sea-bottom, is fortified by innumerable independent lines of evidence;
+and our belief in the truth of the conclusion to which all positive
+testimony tends, receives the like negative justification from the
+fact that no other hypothesis has a shadow of foundation.
+
+It may be worth while briefly to consider a few of these collateral
+proofs that the chalk was deposited at the bottom of the sea.
+
+The great mass of the chalk is composed, as we have seen, of the
+skeletons of Globigerinae, and other simple organisms, imbedded in
+granular matter. Here and there, however, this hardened mud of the
+ancient sea reveals the remains of higher animals which have lived and
+died, and left their hard parts in the mud, just as the oysters die
+and leave their shells behind them, in the mud of the present seas.
+
+[Illustration: UPPER SILURIAN CORALS AND CRUSTACEANS.]
+
+There are, at the present day, certain groups of animals which are
+never found in fresh waters, being unable to live anywhere but in the
+sea. Such are the corals; those corallines which are called Polyzoa;
+those creatures which fabricate the lamp-shells, and are called
+Brachiopoda; the pearly Nautilus, and all animals allied to it; and
+all the forms of sea-urchins and star-fishes.
+
+Not only are all these creatures confined to salt water at the present
+day, but, so far as our records of the past go, the conditions of
+their existence have been the same: hence, their occurrence in any
+deposit is as strong evidence as can be obtained, that that deposit
+was formed in the sea. Now the remains of animals of all the kinds
+which have been enumerated occur in the chalk, in greater or less
+abundance; while not one of those forms of shell-fish which are
+characteristic of fresh water has yet been observed in it.
+
+When we consider that the remains of more than three thousand distinct
+species of aquatic animals have been discovered among the fossils of
+the chalk, that the great majority of them are of such forms as are
+now met with only in the sea, and that there is no reason to believe
+that any one of them inhabited fresh water--the collateral evidence
+that the chalk represents an ancient sea-bottom acquires as great
+force as the proof derived from the nature of the chalk itself. I
+think you will now allow that I did not overstate my case when I
+asserted that we have as strong grounds for believing that all the
+vast area of dry land at present occupied by the chalk was once at the
+bottom of the sea, as we have for any matter of history whatever;
+while there is no justification for any other belief.
+
+[Illustration: CRETACEOUS NAUTILUS.]
+
+No less certain is it that the time during which the countries we now
+call southeast England, France, Germany, Poland, Russia, Egypt,
+Arabia, Syria, were more or less completely covered by a deep sea,
+was of considerable duration.
+
+We have already seen that the chalk is, in places, more than a
+thousand feet thick. I think you will agree with me that it must have
+taken some time for the skeletons of the animalcules of a hundredth of
+an inch in diameter to heap up such a mass as that. I have said that
+throughout the thickness of the chalk the remains of other animals are
+scattered. These remains are often in the most exquisite state of
+preservation. The valves of the shell-fishes are commonly adherent;
+the long spines of some of the sea-urchins, which would be detached by
+the smallest jar, often remain in their places. In a word, it is
+certain that these animals have lived and died when the place which
+they now occupy was the surface of as much of the chalk as had then
+been deposited; and that each has been covered up by the layer of
+Globigerina mud, upon which the creatures imbedded a little higher up
+have, in like manner, lived and died. But some of these remains prove
+the existence of reptiles of vast size in the chalk sea. These lived
+their time, and had their ancestors and descendants, which assuredly
+implies time, reptiles being of slow growth.
+
+There is more curious evidence, again, that the process of covering
+up, or, in other words, the deposit of Globigerina skeletons, did not
+go on very fast. It is demonstrable that an animal of the cretaceous
+sea might die, that its skeleton might lie uncovered upon the
+sea-bottom long enough to lose all its outward coverings and
+appendages by putrefaction; and that, after this had happened, another
+animal might attach itself to the dead and naked skeleton, might grow
+to maturity, and might itself die before the calcareous mud had buried
+the whole.
+
+Cases of this kind are admirably described by Sir Charles Lyell. He
+speaks of the frequency with which geologists find in the chalk a
+fossilized sea-urchin to which is attached the lower valve of a
+Crania. This is a kind of shell-fish, with a shell composed of two
+pieces, of which, as in the oyster, one is fixed and the other free.
+
+"The upper valve is almost invariably wanting, though occasionally
+found in a perfect state of preservation in the white chalk at some
+distance. In this case, we see clearly that the sea-urchin first lived
+from youth to age, then died and lost its spines, which were carried
+away. Then the young Crania adhered to the bared shell, grew and
+perished in its turn; after which, the upper valve was separated from
+the lower, before the Echinus became enveloped in chalky mud."
+
+A specimen in the Museum of Practical Geology, in London, still
+further prolongs the period which must have elapsed between the death
+of the sea-urchin and its burial by the Globigeringae. For the outward
+face of the valve of a Crania, which is attached to a sea-urchin
+(Micrastor), is itself overrun by an incrusting coralline, which
+spreads thence over more or less of the surface of the sea-urchin. It
+follows that, after the upper valve of the Crania fell off, the
+surface of the attached valve must have remained exposed long enough
+to allow of the growth of the whole coralline, since corallines do not
+live imbedded in the mud.
+
+The progress of knowledge may, one day, enable us to deduce from such
+facts as these the maximum rate at which the chalk can have
+accumulated, and thus to arrive at the minimum duration of the chalk
+period. Suppose that the valve of the Crania upon which a coralline
+has fixed itself in the way just described is so attached to the
+sea-urchin that no part of it is more than an inch above the face upon
+which the sea-urchin rests. Then, as the coralline could not have
+fixed itself if the Crania had been covered up with chalk-mud, and
+could not have lived had itself been so covered, it follows, that an
+inch of chalk mud could not have accumulated within the time between
+the death and decay of the soft parts of the sea-urchin and the growth
+of the coralline to the full size which it has attained. If the decay
+of the soft parts of the sea-urchin; the attachment, growth to
+maturity, and decay of the Crania; and the subsequent attachment and
+growth of the coralline, took a year (which is a low estimate enough),
+the accumulation of the inch of chalk must have taken more than a
+year: and the deposit of a thousand feet of chalk must, consequently,
+have taken more than twelve thousand years.
+
+The foundation of all this calculation is, of course, a knowledge of
+the length of time the Crania and the coralline needed to attain their
+full size; and, on this head, precise knowledge is at present wanting.
+But there are circumstances which tend to show that nothing like an
+inch of chalk has accumulated during the life of a Crania; and, on any
+probable estimate of the length of that life, the chalk period must
+have had a much longer duration than that thus roughly assigned to
+it.
+
+Thus, not only is it certain that the chalk is the mud of an ancient
+sea-bottom; but it is no less certain that the chalk sea existed
+during an extremely long period, though we may not be prepared to give
+a precise estimate of the length of that period in years. The relative
+duration is clear, though the absolute duration may not be definable.
+The attempt to affix any precise date to the period at which the chalk
+sea began or ended its existence, is baffled by difficulties of the
+same kind. But the relative age of the cretaceous epoch may be
+determined with as great ease and certainty as the long duration of
+that epoch.
+
+You will have heard of the interesting discoveries recently made, in
+various parts of Western Europe, of flint implements, obviously worked
+into shape by human hands, under circumstances which show conclusively
+that man is a very ancient denizen of these regions.
+
+It has been proved that the old populations of Europe, whose existence
+has been revealed to us in this way, consisted of savages, such as the
+Esquimaux are now; that, in the country which is now France, they
+hunted the reindeer, and were familiar with the ways of the mammoth
+and the bison. The physical geography of France was in those days
+different from what it is now--the river Somme, for instance, having
+cut its bed a hundred feet deeper between that time and this; and it
+is probable that the climate was more like that of Canada or Siberia
+than that of Western Europe.
+
+The existence of these people is forgotten even in the traditions of
+the oldest historical nations. The name and fame of them had utterly
+vanished until a few years back; and the amount of physical change
+which has been effected since their day renders it more than probable
+that, venerable as are some of the historical nations, the workers of
+the chipped flints of Hoxne or of Amiens are to them, as they are to
+us, in point of antiquity.
+
+But, if we assign to these hoar relics of long-vanished generations of
+men the greatest age that can possibly be claimed for them, they are
+not older than the drift, or boulder clay, which, in comparison with
+the chalk, is but a very juvenile deposit. You need go no further than
+your own seaboard for evidence of this fact. At one of the most
+charming spots on the coast of Norfolk, Cromer, you will see the
+boulder clay forming a vast mass, which lies upon the chalk, and must
+consequently have come into existence after it. Huge boulders of chalk
+are, in fact, included in the clay, and have evidently been brought to
+the position they now occupy by the same agency as that which has
+planted blocks of syenite from Norway side by side with them.
+
+The chalk, then, is certainly older than the boulder clay. If you ask
+how much, I will again take you no further than the same spot upon
+your own coasts for evidence. I have spoken of the boulder clay and
+drift as resting upon the chalk. That is not strictly true. Interposed
+between the chalk and the drift is a comparatively insignificant
+layer, containing vegetable matter. But that layer tells a wonderful
+history. It is full of stumps of trees standing as they grew.
+Fir-trees are there with their cones, and hazel-bushes with their
+nuts; there stand the stools of oak and yew trees, beeches and
+alders. Hence this stratum is appropriately called the "forest-bed."
+
+It is obvious that the chalk must have been upheaved and converted
+into dry land before the timber trees could grow upon it. As the bolls
+of some of these trees are from two to three feet in diameter, it is
+no less clear that the dry land thus formed remained in the same
+condition for long ages. And not only do the remains of stately oaks
+and well-grown firs testify to the duration of this condition of
+things, but additional evidence to the same effect is afforded by the
+abundant remains of elephants, rhinoceroses, hippopotamuses, and other
+great wild beasts, which it has yielded to the zealous search of such
+men as the Rev. Mr. Gunn.
+
+When you look at such a collection as he has formed, and bethink you
+that these elephantine bones did veritably carry their owners about,
+and these great grinders crunch, in the dark woods of which the
+forest-bed is now the only trace, it is impossible not to feel that
+they are as good evidence of the lapse of time as the annual rings of
+the tree-stumps.
+
+Thus there is a writing upon the wall of cliffs at Cromer, and whoso
+runs may read it. It tells us, with an authority which cannot be
+impeached, that the ancient sea-bed of the chalk sea was raised up,
+and remained dry land, until it was covered with forest, stocked with
+the great game whose spoils have rejoiced your geologists. How long it
+remained in that condition cannot be said; but "the whirligig of time
+brought its revenges" in those days as in these. That dry land, with
+the bones and teeth of generations of long-lived elephants, hidden
+away among the gnarled roots and dry leaves of its ancient trees, sank
+gradually to the bottom of the icy sea, which covered it with huge
+masses of drift and boulder clay. Sea-beasts, such as the walrus, now
+restricted to the extreme north, paddled about where birds had
+twittered among the topmost twigs of the fir-trees. How long this
+state of things endured we know not, but at length it came to an end.
+The upheaved glacial mud hardened into the soil of modern Norfolk.
+Forests grew once more, the wolf and the beaver replaced the reindeer
+and the elephant; and at length what we call the history of England
+dawned.
+
+Thus you have, within the limits of your own county, proof that the
+chalk can justly claim a very much greater antiquity than even the
+oldest physical traces of mankind. But we may go further and
+demonstrate, by evidence of the same authority as that which testifies
+to the existence of the father of men, that the chalk is vastly older
+than Adam himself.
+
+The Book of Genesis informs us that Adam, immediately upon his
+creation, and before the appearance of Eve, was placed in the garden
+of Eden. The problem of the geographical position of Eden has greatly
+vexed the spirits of the learned in such matters, but there is one
+point respecting which, so far as I know, no commentator has ever
+raised a doubt. This is, that of the four rivers which are said to run
+out of it, Euphrates and Hiddekel are identical with the rivers now
+known by the names of Euphrates and Tigris.
+
+But the whole country in which these mighty rivers take their origin,
+and through which they run, is composed of rocks which are either of
+the same age as the chalk, or of later date. So that the chalk must
+not only have been formed, but, after its formation, the time required
+for the deposit of these later rocks, and for their upheaval into dry
+land, must have elapsed, before the smallest brook which feeds the
+swift stream of "the great river, the river of Babylon," began to
+flow.
+
+       *       *       *       *       *
+
+Thus, evidence which cannot be rebutted, and which need not be
+strengthened, though if time permitted I might indefinitely increase
+its quantity, compels you to believe that the earth, from the time of
+the chalk to the present day, has been the theatre of a series of
+changes as vast in their amount as they were slow in their progress.
+The area on which we stand has been first sea and then land, for at
+least four alternations; and has remained in each of these conditions
+for a period of great length.
+
+Nor have these wonderful metamorphoses of sea into land, and of land
+into sea, been confined to one corner of England. During the chalk
+period, or "cretaceous epoch," not one of the present great physical
+features of the globe was in existence. Our great mountain ranges,
+Pyrenees, Alps, Himalayas, Andes, have all been upheaved since the
+chalk was deposited, and the cretaceous sea flowed over the sites of
+Sinai and Ararat.
+
+All this is certain, because rocks of cretaceous or still later date
+have shared in the elevatory movements which gave rise to these
+mountain chains; and may be found perched up, in some cases, many
+thousand feet high upon their flanks. And evidence of equal cogency
+demonstrates that, though in Norfolk the forest-bed rests directly
+upon the chalk, yet it does so, not because the period at which the
+forest grew immediately followed that at which the chalk was formed,
+but because an immense lapse of time, represented elsewhere by
+thousands of feet of rock, is not indicated at Cromer.
+
+I must ask you to believe that there is no less conclusive proof that
+a still more prolonged succession of similar changes occurred before
+the chalk was deposited. Nor have we any reason to think that the
+first term in the series of these changes is known. The oldest
+sea-beds preserved to us are sands, and mud, and pebbles, the wear and
+tear of rocks which were formed in still older oceans.
+
+But, great as is the magnitude of these physical changes of the world,
+they have been accompanied by a no less striking series of
+modifications in its living inhabitants.
+
+All the great classes of animals, beasts of the field, fowls of the
+air, creeping things, and things which dwell in the waters, flourished
+upon the globe long ages before the chalk was deposited. Very few,
+however, if any, of these ancient forms of animal life were identical
+with those which now live. Certainly not one of the higher animals was
+of the same species as any of those now in existence. The beasts of
+the field, in the days before the chalk, were not our beasts of the
+field, nor the fowls of the air such as those which the eye of man has
+seen flying, unless his antiquity dates infinitely further back than
+we at present surmise. If we could be carried back into those times,
+we should be as one suddenly set down in Australia before it was
+colonized. We should see mammals, birds, reptiles, fishes, insects,
+snails, and the like, clearly recognizable as such, and yet not one of
+them would be just the same as those with which we are familiar, and
+many would be extremely different.
+
+From that time to the present, the population of the world has
+undergone slow and gradual, but incessant, changes. There has been no
+grand catastrophe--no destroyer has swept away the forms of life of
+one period, and replaced them by a totally new creation; but one
+species has vanished and another has taken its place; creatures of one
+type of structure have diminished, those of another have increased, as
+time has passed on. And thus, while the differences between the living
+creatures of the time before the chalk and those of the present day
+appear startling, if placed side by side, we are led from one to the
+other by the most gradual progress, if we follow the course of Nature
+through the whole series of those relics of her operations which she
+has left behind.
+
+[Illustration: SKELETON OF THE PTERODACTYL.]
+
+And it is by the population of the chalk sea that the ancient and the
+modern inhabitants of the world are most completely connected. The
+groups which are dying out flourish, side by side, with the groups
+which are now the dominant forms of life.
+
+Thus the chalk contains remains of those flying and swimming
+reptiles, the pterodactyl, the ichthyosaurus, and the plesiosaurus,
+which are found in no later deposits, but abounded in preceding ages.
+The chambered shells called ammonites and belemnites, which are so
+characteristic of the period preceding the cretaceous, in like manner
+die with it.
+
+[Illustration: THE SKELETON OF THE ICHTHYOSAURUS.]
+
+[Illustration: THE SKELETON OF THE PLESIOSAURUS.]
+
+[Illustration: AMMONITES.]
+
+But, among these fading remainders of a previous state of things, are
+some very modern forms of life, looking like Yankee peddlers among a
+tribe of red Indians. Crocodiles of modern type appear; bony fishes,
+many of them very similar to existing species, almost supplant the
+forms of fish which predominate in more ancient seas; and many kinds
+of living shell-fish first become known to us in the chalk. The
+vegetation acquires a modern aspect. A few living animals are not even
+distinguishable as species from those which existed at that remote
+epoch. The Globigerina of the present day, for example, is not
+different specifically from that of the chalk; and the same may be
+said of many other Foraminifera. I think it probable that critical and
+unprejudiced examination will show that more than one species of much
+higher animals have had a similar longevity; but the only example
+which I can at present give confidently is the snake's-head lamp-shell
+(_Terebratulina caput serpentis_), which lives in our English seas and
+abounded (as _Terebratulina striata_ of authors) in the chalk.
+
+[Illustration: BELEMNITES.]
+
+[Illustration: TEREBRATULINA.]
+
+The longest line of human ancestry must hide its diminished head
+before the pedigree of this insignificant shell-fish. We Englishmen
+are proud to have an ancestor who was present at the Battle of
+Hastings. The ancestors of _Terebratulina caput serpentis_ may have
+been present at a battle of Ichthyosauria in that part of the sea
+which, when the chalk was forming, flowed over the site of Hastings.
+While all around has changed, this Terebratulina has peacefully
+propagated its species from generation to generation, and stands to
+this day as a living testimony to the continuity of the present with
+the past history of the globe.
+
+       *       *       *       *       *
+
+Up to this moment I have stated, so far as I know, nothing but
+well-authenticated facts, and the immediate conclusions which they
+force upon the mind.
+
+But the mind is so constituted that it does not willingly rest in
+facts and immediate causes, but seeks always after a knowledge of the
+remoter links in the chain of causation.
+
+Taking the many changes of any given spot of the earth's surface, from
+sea to land, and from land to sea, as an established fact, we cannot
+refrain from asking ourselves how these changes have occurred. And
+when we have explained them--as they must be explained--by the
+alternate slow movements of elevation and depression which have
+affected the crusts of the earth, we go still further back, and ask,
+Why these movements?
+
+I am not certain that any one can give you a satisfactory answer to
+that question. Assuredly I cannot. All that can be said for certain
+is, that such movements are part of the ordinary course of nature,
+inasmuch as they are going on at the present time. Direct proof may be
+given, that some parts of the land of the northern hemisphere are at
+this moment insensibly rising and others insensibly sinking; and there
+is indirect but perfectly satisfactory proof, that an enormous area
+now covered by the Pacific has been deepened thousands of feet since
+the present inhabitants of that sea came into existence.
+
+Thus there is not a shadow of a reason for believing that the
+physical changes of the globe, in past times, have been effected by
+other than natural causes.
+
+Is there any more reason for believing that the concomitant
+modifications in the forms of the living inhabitants of the globe have
+been brought about in any other ways?
+
+Before attempting to answer this question, let us try to form a
+distinct mental picture of what has happened in some special case.
+
+The crocodiles are animals which, as a group, have a very vast
+antiquity. They abounded ages before the chalk was deposited; they
+throng the rivers in warm climates at the present day. There is a
+difference in the form of the joints of the backbone, and in some
+minor particulars, between the crocodiles of the present epoch and
+those which lived before the chalk; but, in the cretaceous epoch, as I
+have already mentioned, the crocodiles had assumed the modern type of
+structure. Notwithstanding this, the crocodiles of the chalk are not
+identically the same as those which lived in the times called "older
+tertiary," which succeeded the cretaceous epoch; and the crocodiles of
+the older tertiaries are not identical with those of the newer
+tertiaries, nor are these identical with existing forms. I leave open
+the question whether particular species may have lived on from epoch
+to epoch. But each epoch has had its peculiar crocodiles; though all,
+since the chalk, have belonged to the modern type, and differ simply
+in their proportions and in such structural particulars as are
+discernible only to trained eyes.
+
+How is the existence of this long succession of different species of
+crocodiles to be accounted for?
+
+Only two suppositions seem to be open to us--either each species of
+crocodile has been specially created, or it has arisen out of some
+pre-existing form by the operation of natural causes.
+
+Choose your hypothesis; I have chosen mine. I can find no warranty for
+believing in the distinct creation of a score of successive species of
+crocodiles in the course of countless ages of time. Science gives no
+countenance to such a wild fancy; nor can even the perverse ingenuity
+of a commentator pretend to discover this sense, in the simple wrords
+in which the writer of Genesis records the proceeding of the fifth and
+sixth days of the Creation.
+
+On the other hand, I see no good reason for doubting the necessary
+alternative, that all these varied species have been evolved from
+pre-existing crocodilian forms by the operation of causes as
+completely a part of the common order of nature as those which have
+effected the changes of the inorganic world.
+
+Few will venture to affirm that the reasoning which applies to
+crocodiles loses its force among other animals or among plants. If one
+series of species has come into existence by the operation of natural
+causes, it seems folly to deny that all may have arisen in the same
+way.
+
+       *       *       *       *       *
+
+A small beginning has led us to a great ending. If I were to put the
+bit of chalk with which we started into the hot but obscure flame of
+burning hydrogen, it would presently shine like the sun. It seems to
+me that this physical metamorphosis is no false image of what has been
+the result of our subjecting it to a jet of fervent, though nowise
+brilliant, thought to-night. It has become luminous, and its clear
+rays, penetrating the abyss of the remote past, have brought within
+our ken some stages of the evolution of the earth. And in the shifting
+"without haste, but without rest" of the land and sea, as in the
+endless variation of the forms assumed by living beings, we have
+observed nothing but the natural product of the forces originally
+possessed by the substance of the universe.
+
+[Illustration]
+
+
+
+
+A BIT OF SPONGE
+
+(Written on Scotland.)
+
+(FROM GLIMPSES OF NATURE.)
+
+BY A. WILSON.
+
+
+[Illustration]
+
+This morning, despite the promise of rain over-night, has broken with
+all the signs and symptoms of a bright July day. The Firth is bathed
+in sunlight, and the wavelets at full tide are kissing the strand,
+making a soft musical ripple as they retire, and as the pebbles run
+down the sandy slope on the retreat of the waves. Beyond the farthest
+contact of the tide is a line of seaweed dried and desiccated, mixed
+up with which, in confusing array, are masses of shells, and such
+_olla podrida_ of the sea.
+
+Tossed up at our very feet is a dried fragment of sponge, which
+doubtless the unkind waves tore from its rocky bed. It is not a large
+portion of sponge this, but its structure is nevertheless to be fairly
+made out, and some reminiscences of its history gleaned, for the sake
+of occupying the by no means "bad half-hour" before breakfast. "What
+is a sponge?" is a question which you may well ask as a necessary
+preliminary to the understanding of its personality.
+
+[Illustration: A SPONGE ATTACHED TO ITS ROCKY BED.]
+
+The questionings of childhood and the questionings of science run in
+precisely similar grooves. "What is it?" and "How does it live?" and
+"Where does it come from?" are equally the inquiries of childhood, and
+of the deepest philosophy which seeks to determine the whole history
+of life. This morning, we cannot do better than follow in the
+footsteps of the child, and to the question, "What is a sponge?" I
+fancy science will be able to return a direct answer. First of all, we
+may note that a sponge, as we know it in common life, is the horny
+skeleton or framework which was made by, and which supported, the
+living parts. These living parts consist of minute masses of that
+living jelly to which the name of _protoplasm_ has been applied. This,
+in truth, is the universal matter of life. It is the one substance
+with which life everywhere is associated, and as we see it simply in
+the sponge, so also we behold it (only in more complex guise) in the
+man. Now, the living parts of this dried cast-away sponge were found
+both in its interior and on its surface. They lined the canals that
+everywhere permeate the sponge-substance, and microscopic examination
+has told us a great deal about their nature.
+
+
+[Illustration: FIG. 1. DEVELOPMENT OF A SPONGE (_Olynthus_). 1. The
+egg. 2, 3, and 4. The process of egg-division. 5 and 6. The
+gastrula-stage. 7. The perfect sponge.]
+
+For, whether found in the canals of the sponge themselves, or embedded
+in the sponge-substance, the living sponge-particles are represented
+each by a semi-independent mass of protoplasm. So that the first view
+I would have you take of the sponge as a living mass, is, that it is a
+colony and not a single unit. It is composed, in other words, of
+aggregated masses of living particles, which bud out one from the
+other, and manufacture the supporting skeleton we know as "the sponge
+of commerce" itself. Under the microscope, these living sponge-units
+appear in various guises and shapes. Some of them are formless, and,
+as to shape, ever-altering masses, resembling that familiar animalcule
+of our pools we know as the _Amoeba_. These members of the
+sponge-colony form the bulk of the population. They are embedded in
+the sponge substance; they wander about through the meshes of the
+sponge; they seize food and flourish and grow; and they probably also
+give origin to the "eggs" from which new sponges are in due course
+produced.
+
+More characteristic however, are certain units of this living
+sponge-colony which live in the lining membrane of the canals. In
+point of fact, a sponge is a kind of Venice, a certain proportion of
+whose inhabitants, like those of the famous Queen of the Adriatic
+herself, live on the banks of the waterways. Just as in Venice we find
+the provisions for the denizens of the city brought to the inhabitants
+by the canals, so from the water, which, as we shall see, is
+perpetually circulating through a sponge, the members of the
+sponge-colony receive their food.
+
+Look, again, at the sponge-fragment which lies before us. You perceive
+half a dozen large holes or so, each opening on a little eminence, as
+it were. These apertures, bear in mind, we call _oscula_. They are the
+exits of the sponge-domain. But a close inspection of a sponge shows
+that it is riddled with finer and smaller apertures. These latter are
+the _pores_, and they form the entrances to the sponge-domain.
+
+On the banks of the canal you may see growing plentifully in summer
+time a green sponge, which is the common fresh-water species. Now, if
+you drop a living specimen of this species into a bowl of water, and
+put some powdered indigo into the water, you may note how the currents
+are perpetually being swept in by the pores and out by the oscula. In
+every living sponge this perpetual and unceasing circulation of water
+proceeds. This is the sole evidence the unassisted sight receives of
+the vitality of the sponge-colony, and the importance of this
+circulation in aiding life in these depths, to be fairly carried out
+cannot readily be over-estimated.
+
+[Illustration: WHERE SPONGES GROW.]
+
+Let us now see how this circulation is maintained. Microscopically
+regarded, we see here and there, in the sides of the sponge-passages,
+little chambers and recesses which remind one of the passing-places in
+a narrow canal. Lining these chambers, we see living sponge-units of a
+type different from the shapeless specks we noted to occur in the
+meshes of the sponge substance itself. The units of the recesses each
+consist of a living particle, whose free extremity is raised into a
+kind of collar, from which projects a lash-like filament known as a
+flagellum.
+
+This lash is in constant movement. It waves to and fro in the water,
+and the collection of lashes we see in any one chamber acts as a
+veritable brush, which by its movement not only sweeps water in by the
+pores, but sends it onwards through the sponge, and in due time sends
+it out by the bigger holes, or oscula. This constant circulation in
+the sponge discharges more than one important function. For, as
+already noted, it serves the purpose of nutrition, in that the
+particles on which sponge-life is supported are swept into the colony.
+
+Again, the fresh currents of water carry with them the oxygen gas
+which is a necessity of sponge existence, as of human life; while,
+thirdly, waste matters, inevitably alike in sponge and in man as the
+result of living, are swept out of the colony, and discharged into the
+sea beyond. Our bit of sponge has thus grown from a mere dry fragment
+into a living reality. It is a community in which already, low as it
+is, the work of life has come to be discharged by distinct and fairly
+specialized beings.
+
+The era of new sponge-life is inaugurated by means of egg-development,
+although there exists another fashion (that of gemmules or buds)
+whereby out of the parental substance young sponges are produced. A
+sponge-egg develops, as do all eggs, in a definite cycle. It undergoes
+division (Fig. 1); its one cell becomes many; and its many cells
+arrange themselves first of all into a cup-like form (5, 6 and 7),
+which may remain in this shape if the sponge is a simple one, or
+become developed into the more complex shape of the sponges we know.
+
+In every museum you may see specimens of a beautiful vase-like
+structure seemingly made of spun-glass. This is a flinty sponge, the
+"Venus flower-basket," whose presence in the sponge family redeems it
+from the charge that it contains no things of beauty whatever. So,
+too, the rocks are full of fossil-sponges, many of quaint form. Our
+piece of sponge, as we may understand, has yet other bits of history
+attached to it.... Meanwhile, think over the sponge and its ways, and
+learn from it that out of the dry things of life, science weaves many
+a fairy tale.
+
+[Illustration]
+
+
+
+
+THE GREATEST SEA-WAVE EVER KNOWN
+
+(FROM LIGHT SCIENCE IN LEISURE HOURS.)
+
+BY R.A. PROCTOR.
+
+
+[Illustration]
+
+August 13th, 1868, one of the most terrible calamities which has ever
+visited a people befell the unfortunate inhabitants of Peru. In that
+land earthquakes are nearly as common as rain storms are with us; and
+shocks by which whole cities are changed into a heap of ruins are by
+no means infrequent. Yet even in Peru, "the land of earthquakes," as
+Humboldt has termed it, no such catastrophe as that of August, 1868,
+had occurred within the memory of man. It was not one city which was
+laid in ruins, but a whole empire. Those who perished were counted by
+tens of thousands, while the property destroyed by the earthquake was
+valued at millions of pounds sterling.
+
+Although so many months have passed since this terrible calamity took
+place, scientific men have been busily engaged, until quite recently,
+in endeavoring to ascertain the real significance of the various
+events which were observed during and after the occurrence of the
+earthquake. The geographers of Germany have taken a special interest
+in interpreting the evidence afforded by this great manifestation of
+Nature's powers. Two papers have been written recently on the great
+earthquake of August 13th, 1868--one by Professor von Hochsteter, the
+other by Herr von Tschudi, which present an interesting account of the
+various effects, by land and by sea, which resulted from the
+tremendous upheaving force to which the western flanks of the Peruvian
+Andes were subjected on that day. The effects on land, although
+surprising and terrible, only differ in degree from those which have
+been observed in other earthquakes. But the progress of the great
+sea-wave which was generated by the upheaval of the Peruvian shores
+and propagated over the whole of the Pacific Ocean differs altogether
+from any earthquake phenomena before observed. Other earthquakes have
+indeed been followed by oceanic disturbances; but these have been
+accompanied by terrestrial motions, so as to suggest the idea that
+they had been caused by the motion of the sea-bottom or of the
+neighboring land. In no instance has it ever before been known that a
+well-marked wave of enormous proportions should have been propagated
+over the largest ocean tract on our globe by an earth-shock whose
+direct action was limited to a relatively small region, and that
+region not situated in the centre, but on one side of the wide area
+traversed by the wave.
+
+We propose to give a brief sketch of the history of this enormous
+sea-wave. In the first place, however, it may be well to remind the
+reader of a few of the more prominent features of the great shock to
+which this wave owed its origin.
+
+It was at Arequipa, at the foot of the lofty volcanic mountain Misti,
+that the most terrible effects of the great earthquake were
+experienced. Within historic times Misti has poured forth no lava
+streams, but that the volcano is not extinct is clearly evidenced by
+the fact that in 1542 an enormous mass of dust and ashes was vomited
+forth from its crater. On August 13th. 1868, Misti showed no signs of
+being disturbed. So far as the volcanic neighbor was concerned, the
+forty-four thousand inhabitants of Arequipa had no reason to
+anticipate the catastrophe which presently befell them. At five
+minutes past five an earthquake shock was experienced, which, though
+severe, seems to have worked little mischief. Half a minute later,
+however, a terrible noise was heard beneath the earth; a second shock
+more violent than the first was felt, and then began a swaying motion,
+gradually increasing in intensity. In the-course of the first minute
+this motion had become so violent that the inhabitants ran in terror
+out of their houses into the streets and squares. In the next two
+minutes the swaying movement had so increased that the more lightly
+built houses were cast to the ground, and the flying people could
+scarcely keep their feet. "And now," says Von Tschudi, "there followed
+during two or three minutes a terrible scene. The swaying motion which
+had hitherto prevailed changed into fierce vertical upheaval. The
+subterranean roaring increased in the most terrifying manner; then
+were heard the heart-piercing shrieks of the wretched people, the
+bursting of walls, the crashing fall of houses and churches, while
+over all rolled thick clouds of a yellowish-black dust, which, had
+they been poured forth many minutes longer, would have suffocated
+thousands." Although the shocks had lasted but a few minutes, the whole
+town was destroyed. Not one building remained uninjured, and there
+were few which did not lie in shapeless heaps of ruins.
+
+At Tacna and Arica the earth-shock was less severe, but strange and
+terrible phenomena followed it. At the former place a circumstance
+occurred the cause and nature of which yet remain a mystery. About
+three hours after the earthquake--in other words, at about eight
+o'clock in the evening--an intensely brilliant light made its
+appearance above the neighboring mountains. It lasted for fully half
+an hour, and has been ascribed to the eruption of some as yet unknown
+volcano.
+
+At Arica the sea-wave produced even more destructive effects than had
+been caused by the earthquake. About twenty minutes after the first
+earth-shock the sea was seen to retire, as if about to leave the
+shores wholly dry; but presently its waters returned with tremendous
+force. A mighty wave, whose length seemed immeasurable, was seen
+advancing like a dark wall upon the unfortunate town, a large part of
+which was overwhelmed by it. Two ships, the Peruvian corvette America,
+and the United States "double-ender" Wateree, were carried nearly half
+a mile to the north of Arica beyond the railroad which runs to Tacna,
+and there left stranded high and dry. This enormous wave was
+considered by the English vice-consul at Arica to have been fully
+fifty feet in height.
+
+At Chala three such waves swept in after the first shocks of
+earthquake. They overflowed nearly the whole of the town, the sea
+passing more than half a mile beyond its usual limits.
+
+At Islay and Iquique similar phenomena were manifested. At the former
+town the lava flowed in no less than five times, and each time with
+greater force. Afterward the motion gradually diminished, but even an
+hour and a half after the commencement of this strange disturbance the
+waves still ran forty feet above the ordinary level. At Iquique the
+people beheld the inrushing wave while it was still a great way off. A
+dark blue mass of water some fifty feet in height was seen sweeping in
+upon the town with inconceivable rapidity. An island lying before the
+harbor was completely submerged by the great wave, which still came
+rushing on black with the mud and slime it had swept from the
+sea-bottom. Those who witnessed its progress from the upper balconies
+of their houses, and presently saw its black mass rushing close
+beneath their feet, looked on their safety as a miracle. Many
+buildings were indeed washed away, and in the low-lying parts of the
+town there was a terrible loss of life. After passing far inland, the
+wave slowly returned sea-ward, and, strangely enough, the sea, which
+elsewhere heaved and tossed for hours after the first great wave had
+swept over it, here came soon to rest.
+
+At Callao a yet more singular instance was afforded of the effect
+which circumstances may have upon the motion of the sea after a great
+earthquake has disturbed it. In former earthquakes Callao has suffered
+terribly from the effects of the great sea-wave. In fact, on two
+occasions the whole town has been destroyed, and nearly all its
+inhabitants have been drowned, through the inrush of precisely such
+waves as flowed into the ports of Arica and Chala. But upon this
+occasion the centre of subterranean disturbance must have been so
+situated that either the wave was diverted from Callao, or, more
+probably, two waves reached Callao from different sources and at
+different times, so that the two undulations partly counteracted each
+other. Certain it is that, although the water retreated strangely from
+the coast near Callao, insomuch that a wide tract of the sea-bottom
+was uncovered, there was no inrushing wave comparable with those
+described above. The sea afterward rose and fell in an irregular
+manner, a circumstance confirming the supposition that the disturbance
+was caused by two distinct oscillations. Six hours after the
+occurrence of the earth-shock the double oscillations seemed for a
+while to have worked themselves into unison, for at this time three
+considerable waves rolled in upon the town. But clearly these waves
+must not be compared with those which in other instances had made
+their appearance within half an hour of the earth-throes. There is
+little reason to doubt that if the separate oscillations had
+re-enforced each other earlier, Callao would have been completely
+destroyed. As it was, a considerable amount of mischief was effected;
+but the motion of the sea presently became irregular again, and so
+continued until the morning of August 14th, when it began to ebb with
+some regularity. But during the 14th there were occasional renewals of
+the irregular motion, and several days elapsed before the regular ebb
+and flow of the sea were resumed.
+
+Such were among the phenomena presented in the region where the
+earthquake itself was felt. It will be seen at once that within this
+region, or rather along that portion of the sea-coast which falls
+within the central region of disturbance, the true character of the
+sea-wave generated by the earthquake could not be recognized. If a
+rock fall from a lofty cliff into a comparatively shallow sea, the
+water around the place where the rock has fallen is disturbed in an
+irregular manner. The sea seems at one place to leap up and down;
+elsewhere one wave seems to beat against another, and the sharpest eye
+can detect no law in the motion of the seething waters. But presently,
+outside the scene of disturbance, a circular wave is seen to form, and
+if the motion of this wave be watched it is seen to present the most
+striking contrast with the turmoil and confusion at its centre. It
+sweeps onward and outward in a regular undulation. Gradually it loses
+its circular figure (unless the sea-bottom happens to be unusually
+level), showing that although its motion is everywhere regular, it is
+not everywhere equally swift. A wave of this sort, though incomparably
+vaster, swept swiftly away on every side from the scene of the great
+earthquake near the Peruvian Andes. It has been calculated that the
+width of this wave varied from one million to five million feet, or,
+roughly, from two hundred to one thousand miles, while, when in
+mid-Pacific, the length of the wave, measured along its summit in a
+widely-curved path from one side to another of the great ocean,
+cannot have been less than eight thousand miles.
+
+[Illustration: OVER A LARGE PORTION OF ITS COURSE ITS PASSAGE WAS
+UNNOTED.]
+
+We cannot tell how deep-seated was the centre of subterranean action;
+but there can be no doubt it was very deep indeed, because otherwise
+the shock felt in towns separated from each other by hundreds of miles
+could not have been so nearly contemporaneous. Therefore the portion
+of the earth's crust upheaved must have been enormous, for the length
+of the region where the direct effects of the earthquake were
+perceived is estimated by Professor von Hochsteter at no less than
+two hundred and forty miles. The breadth of the region is unknown,
+because the slope of the Andes on one side and the ocean on the other
+concealed the motion of the earth's crust.
+
+The great ocean-wave swept, as we have said, in all directions around
+the scene of the earth-throe. Over a large part of its course its
+passage was unnoted, because in the open sea the effects even of so
+vast an undulation could not be perceived. A ship would slowly rise as
+the crest of the great wave passed under her, and then as slowly sink
+again. This may seem strange, at first sight, when it is remembered
+that in reality the great sea-wave we are considering swept at the
+rate of three or four hundred sea-miles an hour over the larger part
+of the Pacific. But when the true character of ocean-waves is
+understood, when it is remembered that there is no transference of the
+water itself at this enormous rate, but simply a transmission of
+motion (precisely as when in a high wind waves sweep rapidly over a
+cornfield, while yet each cornstalk remains fixed in the ground), it
+will be seen that the effects of the great sea-wave could only be
+perceived near the shore. Even there, as we shall presently see, there
+was much to convey the impression that the land itself was rising and
+falling rather than that the deep was moved. But among the hundreds of
+ships which were sailing upon the Pacific when its length and breadth
+were traversed by the great sea-wave, there was not one in which any
+unusual motion was perceived.
+
+In somewhat less than three hours after the occurrence of the
+earthquake the ocean-wave inundated the port of Coquimbo, on the
+Chilean seaboard, some eight hundred miles from Arica. An hour or so
+later it had reached Constitucion, four hundred and fifty miles
+farther south; and here for some three hours the sea rose and fell
+with strange violence. Farther south, along the shore of Chile, even
+to the island of Chiloe, the shore-wave travelled, though with
+continually diminishing force, owing, doubtless, to the resistance
+which the irregularities of the shore opposed to its progress.
+
+The northerly shore-wave seems to have been more considerable; and a
+moment's study of a chart of the two Americas will show that this
+circumstance is highly significant. When we remember that the
+principal effects of the land-shock were experienced within that angle
+which the Peruvian Andes form with the long north-and-south line of
+the Chilean and Bolivian Andes, we see at once that, had the centre of
+the subterranean action been near the scene where the most destructive
+effects were perceived, no sea-wave, or but a small one, could have
+been sent toward the shores of North America. The projecting shores of
+northern Peru and Ecuador could not have failed to divert the sea-wave
+toward the west; and though a reflected wave might have reached
+California, it would only have been after a considerable interval of
+time, and with dimensions much less than those of the sea-wave which
+travelled southward. When we see that, on the contrary, a wave of even
+greater proportions travelled toward the shores of North America, we
+seem forced to the conclusion that the centre of the subterranean
+action must have been so far to the west that the sea-wave generated
+by it had a free course to the shores of California.
+
+Be this as it may, there can be no doubt that the wave which swept the
+shores of Southern California, rising upward of sixty feet above the
+ordinary sea-level, was absolutely the most imposing of all the
+indirect effects of the great earthquake. When we consider that even
+in San Pedro Bay, fully five thousand miles from the centre of
+disturbance, a wave twice the height of an ordinary house rolled in
+with unspeakable violence only a few hours after the occurrence of the
+earth-throe, we are most strikingly impressed with the tremendous
+energy of the earth's movement.
+
+Turning to the open ocean, let us track the great wave on its course
+past the multitudinous islands which dot the surface of the Pacific.
+
+The inhabitants of the Sandwich Islands, which lie about six thousand
+three hundred miles from Arica, might have imagined themselves safe
+from any effects which could be produced by an earthquake taking place
+so far away from them. But on the night between August 13th and 14th,
+the sea around this island group rose in a surprising manner, insomuch
+that many thought the islands were sinking, and would shortly subside
+altogether beneath the waves. Some of the smaller islands, indeed,
+were for a time completely submerged. Before long, however, the sea
+fell again, and as it did so the observers "found it impossible to
+resist the impression that the islands were rising bodily out of the
+water." For no less than three days this strange oscillation of the
+sea continued to be experienced, the most remarkable ebbs and floods
+being noticed at Honolulu, on the island of Woahoo.
+
+But the sea-wave swept onward far beyond these islands.
+
+At Yokohama, in Japan, more than ten thousand five hundred miles from
+Arica, an enormous wave poured in on August 14th, but at what hour we
+have no satisfactory record. So far as distance is concerned, this
+wave affords most surprising evidence of the stupendous nature of the
+disturbance to which the waters of the Pacific Ocean had been
+subjected. The whole circumference of the earth is but twenty-five
+thousand miles, so that this wave had travelled over a distance
+considerably greater than two-fifths of the earth's circumference. A
+distance which the swiftest of our ships could not traverse in less
+than six or seven weeks had been swept over by this enormous
+undulation in the course of a few hours.
+
+More complete details reach us from the Southern Pacific.
+
+Shortly before midnight the Marquesas Isles and the low-lying Tuamotu
+group were visited by the great wave, and some of these islands were
+completely submerged by it. The lonely Opara Isle, where the steamers
+which run between Panama and New Zealand have their coaling station,
+was visited at about half-past eleven in the evening by a billow which
+swept away a portion of the coal depot. Afterward great waves came
+rolling in at intervals of about twenty minutes, and several days
+elapsed before the sea resumed its ordinary ebb and flow.
+
+It was not until about half-past two on the morning of August 14th
+that the Samoa Isles (sometimes called the Navigator Islands) were
+visited by the great wave. The watchmen startled the inhabitants from
+their sleep by the cry that the sea was about to overwhelm them; and
+already, when the terrified people rushed from their houses, the sea
+was found to have risen far above the highest water-mark. But it
+presently began to sink again, and then commenced a series of
+oscillations, which lasted for several days, and were of a very
+remarkable nature. Once in every quarter of an hour the sea rose and
+fell, but it was noticed that it rose twice as rapidly as it sank.
+This peculiarity is well worth remarking. The eminent physicist Mallet
+speaks thus (we follow Lyell's quotation) about the waves which
+traverse an open sea: "The great sea-wave, advancing at the rate of
+several miles in a minute, consists, in the deep ocean, of a long, low
+swell of enormous volume, having an equal slope before and behind, and
+that so gentle that it might pass under a ship without being noticed.
+But when it reaches the edge of soundings, its front slope becomes
+short and steep, while its rear slope is long and gentle." On the
+shores visited by such a wave, the sea would appear to rise more
+rapidly than it sank. We have seen that this happened on the shores of
+the Samoa group, and therefore the way in which the sea rose and fell
+on the days following the great earthquake gave significant evidence
+of the nature of the sea-bottom in the neighborhood of these islands.
+As the change of the great wave's figure could not have been quickly
+communicated, we may conclude with certainty that the Samoan Islands
+are the summits of lofty mountains, whose sloping sides extend far
+toward the east.
+
+This conclusion affords interesting evidence of the necessity of
+observing even the seemingly trifling details of important phenomena.
+
+The wave which visited the New Zealand Isles was altogether different
+in character, affording a noteworthy illustration of another remark of
+Mallet's. He says that where the sea-bottom slopes in such a way that
+there is water of some depth close inshore, the great wave may roll in
+and do little damage; and we have seen that so it happened in the case
+of the Samoan Islands. But he adds that, "where the shore is shelving
+there will be first a retreat of the water, and then the wave will
+break upon the beach and roll far in upon the land." This is precisely
+what happened when the great wave reached the eastern shores of New
+Zealand, which are known to shelve down to very shallow water,
+continuing far away to sea toward the east.
+
+At about half-past three on the morning of August 14th the water began
+to retreat in a singular manner from the port of Littleton, on the
+eastern shores of the southernmost of the New Zealand Islands. At
+length the whole port was left entirely dry, and so remained for about
+twenty minutes. Then the water was seen returning like a wall of foam
+ten or twelve feet in height, which rushed with a tremendous noise
+upon the port and town. Toward five o'clock the water again retired,
+very slowly as before, not reaching its lowest ebb until six. An hour
+later a second huge wave inundated the port. Four times the sea
+retired and returned with great power at intervals of about two hours.
+Afterward the oscillation of the water was less considerable, but it
+had not wholly ceased until August 17th, and only on the 18th did the
+regular ebb and flow of the tide recommence.
+
+Around the Samoa group the water rose and fell once in every fifteen
+minutes, while on the shores of New Zealand each oscillation lasted no
+less than two hours. Doubtless the different depths of water, the
+irregular conformation of the island groups, and other like
+circumstances, were principally concerned in producing these singular
+variations. Yet they do not seem fully sufficient to account for so
+wide a range of difference. Possibly a cause yet unnoticed may have
+had something to do with the peculiarity. In waves of such enormous
+extent it would be quite impossible to determine whether the course of
+the wave motion was directed full upon a line of shore or more or less
+obliquely. It is clear that in the former case the waves would seem to
+follow each other more swiftly than in the latter, even though there
+were no difference in their velocity.
+
+Far on beyond the shores of New Zealand the great wave coursed,
+reaching at length the coast of Australia. At dawn of August 14th
+Moreton Bay was visited by five well-marked waves. At Newcastle, on
+the Hunter River, the sea rose and fell several times in a remarkable
+manner, the oscillatory motion commencing at half-past six in the
+morning. But the most significant evidence of the extent to which the
+sea-wave travelled in this direction was afforded at Port Fairy,
+Belfast, South Victoria. Here the oscillation of the water was
+distinctly perceived at midday on August 14th; and yet, to reach this
+point, the sea-wave must not only have travelled on a circuitous
+course nearly equal in length to half the circumference of the earth,
+but must have passed through Bass's Straits, between Australia and Van
+Diemen's Land, and so have lost a considerable portion of its force
+and dimensions. When wL remember that had not the effects of the
+earth-shock on the water been limited by the shores of South America,
+a wave of disturbance equal in extent to that which travelled westward
+would have swept toward the east, we see that the force of the shock
+was sufficient to have disturbed the waters of an ocean covering the
+whole surface of the earth. For the sea-waves which reached Yokohama
+in one direction and Port Fairy in another had each traversed a
+distance nearly equal to half the earth's circumference; so that if
+the surface of the earth were all sea, waves setting out in opposite
+directions from the centre of disturbance would have met each other at
+the antipodes of their starting-point.
+
+It is impossible to contemplate the effects which followed the great
+earthquake--the passage of a sea-wave of enormous volume over fully
+one third of the earth's surface, and the force with which, on the
+farthermost limits of its range, the wave rolled in upon shores more
+than ten thousand miles from its starting-place--without feeling that
+those geologists are right who deny that the subterranean forces of
+the earth are diminishing in intensity. It may be difficult, perhaps,
+to look on the effects which are ascribed to ancient earth-throes
+without imagining for a while that the power of modern earthquakes is
+altogether less. But when we consider fairly the share which time had
+in those ancient processes of change, when we see that while mountain
+ranges were being upheaved or valleys depressed to their present
+position, race after race, and type after type appeared on the earth,
+and lived out the long lives which belong to races and to types, we
+are recalled to the remembrance of the great work which the earth's
+subterranean forces are still engaged upon. Even now continents are
+being slowly depressed or upheaved; even now mountain ranges are being
+raised to a new level, tablelands are in process of formation, and
+great valleys are being gradually scooped out. It may need an
+occasional outburst, such as the earthquake of August, 1868, to remind
+us that great forces are at work beneath the earth's surface. But, in
+reality, the signs of change have long been noted. Old shore-lines
+shift their place, old soundings vary; the sea advances in one place
+and retires in another; on every side Nature's plastic hand is at work
+modelling and remodelling the earth, in order that it may always be a
+fit abode for those who are to dwell upon it.
+
+[Illustration]
+
+
+
+
+THE PHOSPHORESCENT SEA
+
+(FROM STUDIES OF ANIMATED NATURE.)
+
+BY W.S. DALLAS.
+
+
+[Illustration]
+
+It is not merely on land that this phenomenon of phosphorescence is to
+be seen in living forms. Among marine animals, indeed, it is a
+phenomenon much more general, much more splendid, and, we may add,
+much more familiar to those who live on our coasts. There must be many
+in the British Isles who have never had the opportunity of seeing the
+light of the glow-worm, but there can be few of those who have
+frequented in summer any part of our coasts, who have never seen that
+beautiful greenish light which is then so often visible, especially on
+our southern shores, when the water is disturbed by the blade of an
+oar or the prow of a boat or ship. In some cases, even on our own
+shores, the phenomenon is much more brilliant, every rippling wave
+being crested with a line of the same peculiar light, and in warmer
+seas exhibitions of this kind are much more common. It is now known
+that this light is due to a minute living form, to which we will
+afterward return.
+
+But before going on to speak in some detail of the organisms to which
+the phosphorescence of the sea is due, it will be as well to mention
+that the kind of phosphorescence just spoken of is only one mode in
+which the phenomenon is exhibited on the ocean. Though sometimes the
+light is shown in continuous lines whenever the surface is disturbed,
+at other times, and, according to M. de Quatrefages, more commonly,
+the light appears only in minute sparks, which, however numerous,
+never coalesce. "In the little channel known as the Sund de Chausez,"
+he writes, "I have seen on a dark night each stroke of the oar kindle,
+as it were, myriads of stars, and the wake of the craft appeared in a
+manner besprinkled with diamonds." When such is the case the
+phosphorescence is due to various minute animals, especially
+crustaceans; that is, creatures which, microscopically small as they
+are, are yet constructed more or less on the type of the lobster or
+cray-fish.
+
+At other times, again, the phosphorescence is still more partial.
+"Great domes of pale gold with long streamers," to use the eloquent
+words of Professor Martin Duncan, "move slowly along in endless
+succession; small silvery disks swim, now enlarging and now
+contracting, and here and there a green or bluish gleam marks the
+course of a tiny, but rapidly rising and sinking globe. Hour after
+hour the procession passes by, and the fishermen hauling in their nets
+from the midst drag out liquid light, and the soft sea jellies,
+crushed and torn piecemeal, shine in every clinging particle. The
+night grows dark, the wind rises and is cold, and the tide changes; so
+does the luminosity of the sea. The pale spectres below the surface
+sink deeper, and are lost to sight, but the increasing waves are
+tinged here and there with green and white, and often along a line,
+where the fresh water is mixing with the salt in an estuary, there is
+a brightness so intense that boats and shores are visible.... But if
+such sights are to be seen on the surface, what must not be the
+phosphorescence of the depths! Every sea-pen is glorious in its light,
+in fact, nearly every eight-armed Alcyonarian is thus resplendent, and
+the social Pyrosoma, bulky and a free swimmer, glows like a bar of hot
+metal with a white and green radiance."
+
+Such accounts are enough to indicate how varied and how general a
+phenomenon is the phosphorescence of the sea. To take notice of one
+tithe of the points of interest summed up in the paragraph just quoted
+would occupy many pages, and we must therefore confine the attention
+to a few of the most interesting facts relating to marine
+phosphorescence.
+
+We will return to that form of marine luminosity to which we first
+referred: what is known as the general or diffused phosphorescence of
+the sea. From this mode of describing it the reader must not infer
+that the surface of the ocean is ever to be seen all aglow in one
+sheet of continuous light. So far, at least, as was ever observed by
+M. de Quatrefages, who studied this phenomenon carefully and during
+long periods on the coasts of Brittany and elsewhere, no light was
+visible when the surface of the sea was perfectly still. On the other
+hand, when the sea exhibits in a high degree the phenomenon of
+diffused phosphorescence no disturbance can be too slight to cause the
+water to shine with that peculiar characteristic gleam. Drop but a
+grain of sand upon its surface, and you will see a point of light
+marking the spot where it falls, and from that point as a centre a
+number of increasing wavelets, each clearly defined by a line of
+light, will spread out in circles all around.
+
+The cause of this diffused phosphorescence was long the subject of
+curiosity, and was long unknown, but more than a hundred years ago (in
+1764) the light was stated by M. Kigaut to proceed from a minute and
+very lowly organism, now known as _Noctiluca miliaris_; and subsequent
+researches have confirmed this opinion. This Noctiluca is a spherical
+form of not more than one-fiftieth of an inch in size, with a slight
+depression or indentation at one point, marking the position of a
+mouth leading to a short digestive cavity, and having close beside it
+a filament, by means of which it probably moves about. The sphere is
+filled with protoplasm, in which there is a nucleus and one or more
+gaps, or "vacuoles." Such is nearly all the structure that can be
+discerned with the aid of the microscope in this simple organism.
+
+Nevertheless, this lowly form is the chief cause of that diffused
+phosphorescence which is sometimes seen over a wide extent of the
+ocean. How innumerable the individuals belonging to this species must
+therefore be, may be left to the imagination. Probably the Noctiluca
+is not rivalled in this respect even by miscroscopic unicellular algae
+which compose the "red snow."
+
+By filtering sea-water containing Noctilucae its light can be
+concentrated, and it has been found that a few teaspoonfuls will then
+yield light enough to enable one to read holding a book at the
+ordinary distance from the eyes--about ten inches.
+
+A singular and highly remarkable case of diffused marine
+phosphorescence was observed by Nordenskioeld during his voyage to
+Greenland in 1883. One dark night, when the weather was calm and the
+sea smooth, his vessel was steaming across a narrow inlet called the
+Igaliko Fjord, when the sea was suddenly observed to be illumined in
+the rear of the vessel by a broad but sharply-defined band of light,
+which had a uniform, somewhat golden sheen, quite unlike the ordinary
+bluish-green phosphorescence of the sea. The latter kind of light was
+distinctly visible at the same time in the wake of the vessel. Though
+the steamer was going at the rate of from five to six miles an hour,
+the remarkable sheet of light got nearer and nearer. When quite close,
+it appeared as if the vessel were sailing in a sea of fire or molten
+metal. In the course of an hour the light passed on ahead, and
+ultimately it disappeared in the remote horizon. The nature of this
+phenomenon Nordenskioeld is unable to explain; and unfortunately he had
+not the opportunity of examining it with the spectroscope.
+
+If we come now to consider the more partial phosphorescence of the
+sea, we find that it is due to animals belonging to almost every group
+of marine forms--to Echinoderms, or creatures of the sea-urchin and
+star-fish type, to Annelid worm, to Medusidae, or jelly-fish, as they
+are popularly called, including the "great domes" and the "silvery
+disks" of the passage above quoted from Professor Martin Duncan, to
+Tunicates, among which is the Pyrosoma, to Mollusks, Crustaceans, and
+in very many cases to Actinozoa, or forms belonging to the type of the
+sea anemone and the coral polyp.
+
+Of these we will single out only a few for more special notice.
+
+Many of the Medusidae, or jelly-fish, possess the character of which we
+are speaking. In some cases the phosphorescence is spontaneous among
+them, but in others it is not so; the creature requires to be
+irritated or stimulated in some way before it will emit the light. It
+is spontaneous, for example, in the _Pelagia phosphorea_, but not in
+the allied _Pelagia noctiluca_, a very common form in the
+Mediterranean.
+
+In both of the jelly-fishes just mentioned the phosphorescence, when
+displayed at all, is on the surface of the swimming disk, and this is
+most commonly the case with the whole group. Sometimes, however, the
+phosphorescence is specially localized. In some forms, as in
+_Thaumantius pilosella_ and other members of the same genus, it is
+seen in buds at the base of tentacles given off from the margin of the
+swimming-bell. In other cases it is situated in certain internal
+organs, as in the canals which radiate from the centre to the margin
+of the bell, or in the ovaries. It is from this latter seat that the
+phosphorescence proceeds in _Oceania pilata_, the form which gives out
+such a light that Ehrenberg compared it to a lamp-globe lighted by a
+flame.
+
+The property of emitting a phosphorescent light, sometimes
+spontaneously and sometimes on being stimulated, is likewise
+exemplified in the Ctenophora, a group resembling the Medusidge in
+the jelly-like character of their bodies, but more closely allied in
+structure to the Actinozoa. But we will pass over these cases in order
+to dwell more particularly on the remarkable tunicate known as
+Pyrosoma, a name indicative of its phosphorescent property, being
+derived from two Greek words signifying fire-body. As shown in the
+illustration Pyrosoma is not a single creature, but is composed of a
+whole colony of individuals, each of which is represented by one of
+the projections on the surface of the tube, closed at one end, which
+they all combine to form. The free end on the exterior contains the
+mouth, while there is another opening in each individual toward the
+interior of the tube. Such colonies, which swim about by the alternate
+contraction and dilatation of the individuals composing them, are
+pretty common in the Mediterranean, where they may attain the length
+of perhaps fourteen inches, with a breadth of about three inches. In
+the ocean they may reach a much greater size. Mr. Moseley, in his
+"Notes of a Naturalist on the Challenger," mentions a giant specimen
+which he once caught in the deep-sea trawl, a specimen four feet in
+length and ten inches in diameter, with "walls of jelly about an inch
+in thickness."
+
+[Illustration: A. PYROSOMA. B. PONITON. (Magnified.)]
+
+The same naturalist states that the light emitted by this compound
+form is the most beautiful of all kinds of phosphorescence. When
+stimulated by a touch, or shake, or swirl of the water, it "gives out
+a globe of bluish light, which lasts for several seconds, as the
+animal drifts past several feet beneath the surface, and then suddenly
+goes out." He adds that on the giant specimen just referred to be
+wrote his name with his finger as it lay on the deck in a tub at
+night, and in a few seconds he had the gratification of seeing his
+name come out in "letters of fire."
+
+Among mollusks, the best known instance of phosphorescence is in the
+rock-boring Pholas, the luminosity of which after death is mentioned
+by Pliny. But it is not merely after death that Pholas becomes
+luminous--a phenomenon perfectly familiar even in the case of many
+fish, especially the herring and mackerel. It was long before the
+luminosity of the living animal was known, but this is now a
+well-ascertained fact; and Panceri, an Italian naturalist, recently
+dead, has been able to discover in this, as in several other marine
+phosphorescent forms, the precise seat of the light-giving bodies,
+which he has dissected out again and again for the sake of making
+experiments in connection with this subject.
+
+A more beautiful example of a phosphorescent mollusk is presented by a
+sea-slug called _Phyllirhoe bucephala_. This is a creature of from one
+and a half to two inches in length, without a shell in the adult
+stage, and without even gills. It breathes only by the general surface
+of the body. It is common enough in the Mediterranean, but is not easy
+to see, as it is almost perfectly transparent, so that it cannot be
+distinguished without difficulty, by day at least, from the medium in
+which it swims. By night, however, it is more easily discerned, in
+consequence of its property of emitting light. When disturbed or
+stimulated in any way, it exhibits a number of luminous spots of
+different sizes irregularly distributed all over it, but most thickly
+aggregated on the upper and under parts. These phosphorescent spots,
+it is found, are not on the surface, but for the most part represent
+so many large cells which form the terminations of nerves, and are
+situated underneath the transparent cuticle. The spots shine with
+exceptional brilliancy when the animal is withdrawn from the water and
+stimulated by a drop of ammonia.
+
+Among the Annelid worms a species of _Nereis_, or sea-centipedes, has
+earned by its phosphorescent property the specific name of _noctiluca_
+(night-shining), and the same property is very beautifully shown in
+_Polynoe_, a near ally of the familiar sea-mouse. M. de Quatrefages
+speaks with enthusiasm of the beauty of the spectacle presented by
+this latter form when examined under a microscope magnifying to the
+extent of a hundred diameters. He then found, as he did in the great
+majority of cases which he studied, that the phosphorescence was
+confined to the motor muscles, and was manifested solely when these
+were in the act of contracting, manifested, too, not in continuous
+lines along the course of the muscles, but in rows of brilliant
+points.
+
+More interesting than the Annelids, however, are the Alcyonarian
+Actinozoa. The Actinozoa have already been described as formed on the
+type of the sea-anemone and the coral polyp, that is, they are all
+animals with a radiate structure, attached to one end, and having
+their only opening at the other end, which is surrounded by tentacles.
+In the Alcyonarian forms belonging to this great group these tentacles
+are always eight in number, and fringed on both sides. Moreover, these
+forms are almost without exception compound. Like the Pyrosoma, they
+have a common life belonging to a whole stock or colony, as well as an
+individual life.
+
+Now, throughout this sub-division of the Actinozoa phosphorescence is
+a very general phenomenon. Professor Moseley, already quoted as a
+naturalist accompanying the Challenger expedition, informs us that
+"all the Alcyonarians dredged by the Challenger in deep water were
+found to be brilliantly phosphorescent when brought to the surface."
+
+Among these Alcyonarians are the sea-pens mentioned in the quotation
+above made from Professor Martin Duncan. Each sea-pen is a colony of
+Alcyonarians, and the name is due to the singular arrangement of the
+individuals upon the common stem. This stem is supported internally by
+a coral rod, but its outer part is composed of fleshy matter belonging
+to the whole colony. The lower portion of it is fixed in the muddy
+bottom of the sea, but the upper portion is free, and gives off a
+number of branches, on which the individual polyps are seated. The
+whole colony thus has the appearance of a highly ornamental pen.
+
+There is one British species, _Pennatula phosphorea_, which is found
+in tolerably deep water, and is from two to four inches in length. The
+specific name again indicates the phosphorescent quality belonging to
+it. When irritated, it shines brilliantly, and the curious thing is
+that the phosphorescence travels gradually on from polyp to polyp,
+starting from the point at which the irritation is applied. If the
+lower part of the stem is irritated, the phosphorescence passes
+gradually upwards along each pair of branches in succession; but if
+the top is irritated the phosphorescence will pass in the same way
+downwards. When both top and bottom are irritated simultaneously two
+luminous currents start at once, and, meeting in the middle, usually
+become extinguished there; but on one occasion Panceri found that the
+two crossed, and each completed its course independently of the other.
+Those of our readers who have had opportunities of making or seeing
+experiments with the sensitive plant (_Mimosa pudica_) will be
+reminded of the way in which, when that plant is irritated, the
+influence travels regularly on from pinnules to pinnules and pinnae to
+pinnae.
+
+In all the cases mentioned the phenomenon of phosphorescence is
+exhibited by invertebrate animals; but though rare, it is not an
+unknown phenomenon even in living vertebrates. In a genus of deep-sea
+fishes called Stomias, Gunther mentions that a "series of
+phosphorescent dots run along the lower side of the head, body, and
+tail." Several other deep-sea fishes, locally phosphorescent, seem to
+have been dredged up by the French ship Talisman in its exploring
+cruise off the west coast of Northern Africa in 1883. During the same
+expedition, a number of deep-sea phosphorescent crustaceans were
+dredged up, the phosphorescence being in some cases diffused over the
+whole body, in other cases localized to particular areas. In deep-sea
+forms the phenomenon is, in fact, so common, as to have given rise to
+the theory that in the depths of the ocean, where the light of the
+sun cannot penetrate, the phosphorescence of various organisms diffuse
+a light which limits the domain of absolute darkness.
+
+So much by way of illustration regarding the phosphorescence exhibited
+by animals, terrestrial and marine; but it ought to be noticed that
+there are also a few cases in which the same phenomenon is to be
+witnessed in plants. These are not so numerous as was at one time
+supposed, the property having been mistakenly ascribed to some plants
+not really luminous.
+
+[Illustration: A PHOSPHORESCENT SEA.]
+
+In some instances the mistake appears to have been due to a subjective
+effect produced by brilliantly colored (red or orange) flowers, such
+as the great Indian cress, the orange lily, the sunflower, and the
+marigold. The fact that such flowers do give out in the dusk sudden
+flashes of light has often been stated on the authority of a daughter
+of Linnaeus, subsequently backed by the assertions of various other
+observers. But most careful observers seem to be agreed that the
+supposed flashes of light are in reality nothing else than a certain
+dazzling of the eyes.
+
+In another case, in which a moss, _Schistostega osmundacea_, has been
+stated to be phosphorescent, the effect is said to be really due to
+the refraction and reflection of light by minute crystals scattered
+over its highly cellular leaves, and not to be produced at all where
+the darkness is complete.
+
+Among plants, genuine phosphorescence is to be found chiefly in
+certain fungi, the most remarkable of which is _Rhizomorpha
+subterranea_, which is sometimes to be seen ramifying over the walls
+of dark, damp mines, caverns, or decayed towers, and emitting at
+numerous points a mild phosphorescent light, which is sometimes bright
+enough to allow of surrounding objects being distinguished by it. The
+name of "vegetable glow-worm" has sometimes been applied to this
+curious growth.
+
+Among other phosphorescent fungi are several species of Agaricus,
+including the _A. olearius_ of Europe, _A. Gardneri_ of Brazil, and
+_A. lampas_ of Australia, and besides the members of this genus,
+_Thelaphora caerulea_, which is the cause of the phosphorescent light
+sometimes to be seen on decaying wood--the "touchwood" which many boys
+have kept in the hope of seeing this light displayed. The milky juice
+of a South American Euphorbia (_E. phosphorea_) is stated by Martins
+to be phosphorescent when gently heated. But phosphorescence is
+evidently not so interesting and important a phenomenon in the
+vegetable as it is in the animal kingdom.
+
+The whole phenomenon is one that gives rise to a good many questions
+which it is not easy to answer, and this is especially true in the
+case of animal phosphorescence. What is the nature of the light? What
+are the conditions under which it is manifested? What purpose does it
+serve in the animal economy?
+
+As to the nature of the light, the principal question is whether it is
+a direct consequence of the vital activity of the organism in which it
+is seen, of such a nature that no further explanation can be given of
+it, any more than we can explain why a muscle is contracted under the
+influence of a nerve-stimulus; or whether it is due to some chemical
+process more or less analogous to the burning of a candle.
+
+The fact of luminosity appearing to be in certain cases directly under
+the control of the creature in which it is found, and the fact of its
+being manifested in many forms, as M. de Quatrefages found, only when
+muscular contraction was taking place, would seem to favor the former
+view. On the other hand, it is against this view that the
+phosphorescence is often found to persist after the animal is dead,
+and even in the phosphorescent organs for a considerable time after
+they have been extracted from the body of the animal. In the glow-worm
+the light goes on shining for some time after the death of the insect,
+and even when it has become completely extinguished it can be restored
+for a time by the application of a little moisture. Further, both
+Matteucci and Phipson found that when the luminous substance was
+extracted from the insect it would keep on glowing for thirty or forty
+minutes.
+
+In Pholas the light is still more persistent, and it is found that
+when the dead body of this mollusk is placed in honey, it will retain
+for more than a year the power of emitting light when plunged in warm
+water.
+
+The investigations of recent years have rendered it more and more
+probable that the light exhibited by phosphorescent organisms is due
+to a chemical process somewhat analogous to that which goes on in the
+burning of a candle. This latter process is one of rapid oxidation.
+The particles of carbon supplied by the oily matter that feeds the
+candle become so rapidly combined with oxygen derived from the air
+that a considerable amount of light, along with heat, is produced
+thereby. Now, the phenomenon of phosphorescence in organic forms,
+whether living or dead, appears also to be due to a process of
+oxidation, but one that goes on much more slowly than in the case of a
+lighted candle. It is thus more closely analogous to what is observed
+in the element phosphorus itself, which owes its name (meaning
+"light-bearer") to the fact that when exposed to the air at ordinary
+temperatures it glows in the dark, in consequence of its becoming
+slowly combined with oxygen.
+
+At one time it was believed that the presence of oxygen was not
+necessary to the exhibition of phosphorescence in organic forms, but
+it has now been placed beyond doubt that this is a mistake. Oxygen has
+been proved to be indispensable, and hence we see a reason for the
+luminous organs in the glow-worm being so intimately connected, as
+above mentioned, with the air-tubes that ramify through the insect.
+
+This fact of itself might be taken as a strong indication of the
+chemical nature of the process to which phosphorescence is due. But
+the problem has been made the subject of further investigations which
+have thrown more light upon it. It was long known that there were
+various inorganic bodies besides phosphorus which emitted a
+phosphorescent light in the dark, at least after being exposed to the
+rays of the sun; but it was not till quite recently that any organic
+compound was known to phosphoresce at ordinary temperatures.
+
+This discovery was made by a Polish chemist, named Bronislaus
+Radziszewski, who followed it up with a long series of experiments on
+the phosphorescence of organic compounds, by which he was able to
+determine the conditions under which that phenomenon was exhibited. In
+all the substances investigated by him in which phosphorescence was
+introduced he found that three conditions were essential to its
+production: (1) that oxygen should be present; (2) that there should
+be an alkaline reaction in the phosphorescing mixture--that is, a
+reaction such as is produced on acids and vegetable coloring matters
+by potash, soda, and the other alkalies; and (3) that some kind of
+chemical action should take place.
+
+He found, moreover, that among the organic compounds that could be
+made to phosphoresce under these conditions were nearly all the fixed
+and ethereal oils. With reference to the phosphorescence of animals,
+this observation is important, for it has been shown in a great many
+cases that a fatty substance forms the main constituent in their
+luminous organs. This has long been known to be the case in the
+luminous insects belonging to the Lampyridae and Elateridae, as well as
+in the luminous centipedes; and the researches of Panceri, already
+referred to, on the luminous organs of many marine forms have shown
+that it holds good with regard to these also.
+
+We may, therefore, conclude that substances fitted to phosphoresce
+under the conditions determined by the experiments of Radziszewski are
+generally, and probably universally, present in the luminous organs of
+phosphorescent animals. Now, what is to be said as to the occurrence
+of these conditions? The access of oxygen is in all cases easy to
+account for, but it must also be shown how the alkaline reaction is to
+be produced. We need not expect to find in animal organisms potash,
+soda, ammonia, and the other common alkalies; but it was established
+by experiment that the alkaline organic compounds cholin and neurin,
+which are present in animal tissues, would also serve to bring about
+the phenomenon of phosphorescence in the substances on which the
+experiments were made.
+
+Accordingly, it seems fair to conclude that when all these conditions
+for the production of phosphorescence in a chemical laboratory are
+present in animal organisms, the phenomenon, when observed in these,
+is exactly of the same nature as that which is produced artificially.
+By that it is meant that animal phosphorescence is attended, like the
+artificial phenomenon, by a slow chemical action, or in other words,
+that the phosphorescent light is due to a gradual process of
+oxidation.
+
+One curious circumstance has been discovered which lends still further
+probability to this explanation. It was mentioned above that among
+phosphorescent plants there are several species of Agaricus. Now,
+from one species of this genus, though not indeed one of the
+phosphorescent species (from _A. muscarius_) there has been extracted
+a principle called _amanitia_, which is found to be identical with
+cholin. In the light of the results derived from the investigations
+just referred to it is reasonable to draw the conclusion that, if
+sought for, this principle would likewise be found in the
+phosphorescent species in which the other conditions of
+phosphorescence are also present.
+
+On this theory of the production of the phenomenon now under
+consideration, the effect of shaking or of vital action in giving rise
+to or intensifying the exhibition of the light is accounted for by the
+fact that by these means fresh supplies of oxygen are brought into
+contact with the phosphorescent substance. The effect of ammonia on
+the light emitted by the sea-slug _Phyllirhoe bucephala_, is also
+fully explained, ammonia being one of those alkaline substances which
+are so directly favorable to the exhibition of the phenomenon.
+
+Nor is it difficult to account for the control which in some cases
+insects appear to have over the luminosity of the phosphorescent
+organs, exhibiting and withdrawing the light at will. It is not
+necessary to suppose that this is an immediate effect, a conversion of
+nerve force into light, and a withdrawal of that force. The action of
+the creature's will may be merely in maintaining or destroying the
+conditions under which the light is manifested. It may, for example,
+have the power of withdrawing the supply of oxygen, and this
+supposition receives some countenance from the observation cited from
+Kirby and Spence on the two captured glow-worms, one of which
+withdrew its light, while the other kept it shining, but while doing
+so had the posterior extremity of the abdomen in constant motion. But
+the animal may also have the power in another way of affecting the
+chemical conditions of the phenomenon. It may, for example, have the
+power of increasing or diminishing by some nervous influence the
+supply of the necessary alkaline ingredient.
+
+But if animal phosphorescence is really due to a process of slow
+oxidation, there is one singular circumstance to be noted in
+connection with it. Oxidation is a process that is normally
+accompanied by the development of heat. Even where no light is
+produced an increase of temperature regularly takes place when
+substances are oxidized. We ought, then, to expect such a rise of
+temperature when light is emitted by the phosphorescent organs of
+animals. But the most careful observations have shown that nothing of
+the kind can be detected. It was with a view to test this that Panceri
+dissected out the luminous organs of so many specimens of Pholas. He
+selected this mollusk because it was so abundant in the neighborhood
+of Naples, where, his experiments were made; and in making his
+experiments he made use of a thermopile, an apparatus by which, with
+the aid of electricity, much smaller quantities of heat can be
+indicated than by means of the most delicate thermometer. The organs
+remained luminous long after they were extracted, but no rise in
+temperature whatever could be found to accompany the luminosity. Many
+experiments upon different animals were made with similar negative
+results by means of the thermometer.
+
+The only explanation of this that can be given is probably to be found
+in the fact that the chemical process ascertained to go on in the
+phosphorescence of organic compounds on which experiments were made in
+the laboratory is an extremely slow one.
+
+The so-called phosphorescence of most inorganic bodies is one of a
+totally different nature from that exhibited in organic forms. The
+diamond shines for a time in the dark after it has been exposed to the
+sun; so do pieces of quartz when rubbed together, and powdered
+fluor-spar when heated shines with considerable brilliancy. Various
+artificial compounds, such as sulphide of calcium (Canton's
+phosphorus, as it is called from the discoverer), sulphate of barium
+(Bologna stone, or Bologna phosphorus), sulphide of strontium, etc.,
+after being illuminated by the rays of the sun, give out in the dark a
+beautiful phosphorescence, green, blue, violet, orange, red, according
+to circumstances. The luminous paint which has recently attracted so
+much attention is of the same nature. In these cases what we have is
+either a conversion of heat rays into light rays (as in the powdered
+fluor-spar), or the absorption and giving out again of sun-rays. In
+the latter case the phenomenon is essentially the same as
+fluorescence, in which the dark rays of the solar spectrum beyond the
+violet are made visible.
+
+But we must now return to the other questions that have been started
+in relation to phosphorescence in animals. There has been much
+speculation as to the object of this light, and to the purposes it
+serves in Nature. Probably no general answer can be given to this
+question. It is no doubt impossible to show why so many animals have
+been endowed with this remarkable property; but we may consider some
+of the effects which the possession of it has in different cases.
+
+In the first place, it will undoubtedly serve in many cases to afford
+light to enable the animal to see by, and in the Lampyridae it would
+seem that the degree of luminosity is related to the development of
+the vision. In that family, according to the Rev. H.S. Gorham, the
+eyes are developed, as a rule, in inverse proportion to the
+luminosity. Where there is an ample supply of this kind of light the
+eyes are small, but where the light is insignificant the eyes are
+large by way of compensation. And moreover, where both eyes and light
+are small, then the antennae are large and feathery, so that the
+deficiency in the sense of sight is made up for by an unusual
+development in the organs of touch.
+
+But it is none the less certain that the presence of this light cannot
+always be designed to serve this purpose, for many of the animals so
+endowed are blind. The phosphorescent centipedes are without eyes,
+like all the other members of the genus (_Geophilus_) to which they
+belong, and probably the majority of phosphorescent marine forms are
+likewise destitute of organs of sight.
+
+Another suggestion is that the light derived from these marine forms,
+and especially from deep-sea Alcyonarians, is what enables the members
+of the deep-sea fauna that are possessed of eyes (which are always
+enormously enlarged) to see. Such is the suggestion of Dr. Carpenter,
+Sir Wyville Thomson, and Mr. Gwyn Jeffries; and it is possible that
+this actually is one of the effects of the phosphorescent property.
+But if so, it remains to inquire how the forms endowed with it came
+to be possessed of a power useful in that way to other forms, but not
+to themselves. According to the Darwinian doctrine of development, the
+powers that are developed in different organisms by the process of
+natural selection are such as are useful to themselves and not to
+others, unless incidentally.
+
+This consideration has led to another suggestion, namely, that the
+property of phosphorescence serves as a protection to the forms
+possessing it, driving away enemies in one way or another: it may be
+by warning them of the fact that they are unpalatable food, as is
+believed to be the case with the colors of certain brilliantly-colored
+caterpillars; it may be in other ways. In Kirby and Spence one case is
+recorded in which the phosphorescence of the common phosphorescent
+centipede (_Geophilus electricus_) was actually seen apparently to
+serve as a means of defence against an enemy. "Mr. Shepherd," says
+that authority, "once noticed a scarabeus running round the
+last-mentioned insect when shining, as if wishing, but afraid to
+attack it." In the case of the jelly-fishes, it has been pointed out
+that their well-known urticating or stinging powers would make them at
+least unpleasant, if not dangerous, food for fishes; and that
+consequently the luminosity by which so many of them are characterized
+at night may serve at once as a warning to predatory fishes and as a
+protection to themselves. The experience of the unpleasant properties
+of many phosphorescent animals may likewise have taught fishes to
+avoid all forms possessing this attribute, even though many of them
+might be quite harmless.
+
+Lastly, it has been suggested that the phosphorescence in the female
+glow-worm may be designed to attract the male; and that it will
+actually have this effect may readily be taken for granted.
+Observation shows that the male glow-worm is very apt to be attracted
+by a light. Gilbert White of Selborne mentions that they, attracted by
+the light of the candles, came into his parlor. Another observer
+states that by the same light he captured as many as forty male
+glow-worms in one night.
+
+[Illustration]
+
+
+
+
+COMETS
+
+(FROM MARVELS OF THE HEAVENS.)
+
+BY CAMILLE FLAMMARION.
+
+
+  "Je viens vous annoncer une grande nouvelle:
+  Nous l'avons, en dormant, madame, echappe belle.
+  Un monde pres de nous a passe tout du long,
+  Est chu tout au travers de notre tourbillon;
+  Et s'il eut en chemin rencontre notre terre,
+  Elle eut ete brisee en morceaux comme verre."
+                                           MOLIERE.
+
+[Illustration]
+
+This announcement of Trissontin's to Philaminte, who begins the parody
+on the fears caused by the appearance of comets, would not have been a
+parody four or five centuries ago. These tailed bodies, which suddenly
+come to light up the heavens, were for long regarded with terror, like
+so many warning signs of divine wrath. Men have always thought
+themselves much more important than they really are in the universal
+order; they have had the vanity to pretend that the whole creation was
+made for them, whilst in reality the whole creation does not suspect
+their existence. The Earth we inhabit is only one of the smallest
+worlds; and therefore it can scarcely be for it alone that all the
+wonders of the heavens, of which the immense majority remains hidden
+from it, were created. In this disposition of man to see in himself
+the centre and the end of everything, it was easy indeed to consider
+the steps of nature as unfolded in his favor; and if some unusual
+phenomenon presented itself, it was considered to be without doubt a
+warning from Heaven. If these illusions had had no other result than
+the amelioration of the more timorous of the community one would
+regret these ages of ignorance; but not only were these fancied
+warnings of no use, seeing that once the danger passed, man returned
+to his former state; but they also kept up among people imaginary
+terrors, and revived the fatal resolutions caused by the fear of the
+end of the world.
+
+When one fancies the world is about to end,--and this has been
+believed for more than a thousand years,--no solicitude is felt in the
+work of improving this world; and, by the indifference or disdain into
+which one falls, periods of famine and general misery are induced
+which at certain times have overtaken our community. Why use the
+wealth of a world which is going to perish? Why work, be instructed,
+or rise in the progress of the sciences or arts? Much better to forget
+the world, and absorb one's self in the barren contemplation of an
+unknown life. It is thus that ages of ignorance weigh on man, and
+thrust him further and further into darkness, while Science makes
+known by its influence on the whole community, its great value, and
+the magnitude of its aim.
+
+The history of a comet would be an instructive episode of the great
+history of the heavens. In it could be brought together the
+description of the progressive movement of human thought, as well as
+the astronomical theory of these extraordinary bodies. Let us take,
+for example, one of the most memorable and best-known comets, and give
+an outline of its successive passages near the Earth. Like the
+planetary worlds, Comets belong to the solar system, and are subject
+to the rule of the Star King. It is the universal law of gravitation
+which guides their path; solar attraction governs them, as it governs
+the movement of the planets and the small satellites. The chief point
+of difference between them and the planets is, that their orbits are
+very elongated; and, instead of being nearly circular, they take the
+elliptical form. In consequence of the nature of these orbits, the
+same comet may approach very near the Sun, and afterwards travel from
+it to immense distances. Thus, the period of the Comet of 1680 has
+been estimated at three thousand years. It approaches the Sun, so as
+to be nearer to it than our Moon is to us, whilst it recedes to a
+distance 853 times greater than the distance of the Earth from the
+Sun. On the 17th of December, 1680, it was at its perihelion--that is,
+at its greatest proximity to the Sun; it is now continuing its path
+beyond the Neptunian orbit. Its velocity varies according to its
+distance from the solar body. At its perihelion it travels thousands
+of leagues per minute; at its aphelion it does not pass over more than
+a few yards. Its proximity to the Sun in its passage near that body
+caused Newton to think that it received a heat twenty-eight thousand
+times greater than that we experience at the summer solstice; and
+that this heat being two thousand times greater than that of red-hot
+iron, an iron globe of the same dimensions would be fifty thousand
+years entirely losing its heat. Newton added that in the end comets
+will approach so near the Sun that they will not be able to escape the
+preponderance of its attraction, and that they will fall one after the
+other into this brilliant body, thus keeping up the heat which it
+perpetually pours out into space. Such is the deplorable end assigned
+to comets by the author of the "Principia," an end which makes De la
+Bretonne say to Retif: "An immense comet, already larger than Jupiter,
+was again increased in its path by being blended with six other dying
+comets. Thus displaced from its ordinary route by these slight shocks,
+it did not pursue its true elliptical orbit; so that the unfortunate
+thing was precipitated into the devouring centre of the Sun." "It is
+said," added he, "that the poor comet, thus burned alive, sent forth
+dreadful cries!"
+
+[Illustration: A COMET]
+
+It will be interesting, then, in a double point of view, to follow a
+comet in its different passages in sight of the Earth. Let us take the
+most important in astronomical history--the one whose orbit has been
+calculated by Edmund Halley, and which was named after him. It was in
+1682 that this comet appeared in its greatest brilliancy, accompanied
+with a tail which did not measure less than thirty-two millions of
+miles. By the observation of the path which it described in the
+heavens, and the time it occupied in describing it, this astronomer
+calculated its orbit, and recognized that the comet was the same as
+that which was admired in 1531 and 1607, and which ought to have
+reappeared in 1759. Never did scientific prediction excite a more
+lively interest. The comet returned at the appointed time; and on the
+12th of March, 1759, reached its perihelion. Since the year 12 before
+the Christian era, it had presented itself twenty-four times to the
+Earth. It was principally from the astronomical annals of China that
+it was possible to follow it up to this period.
+
+Its first memorable appearance in the history of France is that of
+837, in the reign of Louis le Debonnaire. An anonymous writer of
+chronicles of that time, named "The Astronomer," gave the following
+details of this appearance, relative to the influence of the comet on
+the imperial imagination:
+
+"During the holy days of the solemnization of Easter, a phenomenon
+ever fatal, and of gloomy foreboding, appeared in the heavens. As soon
+as the Emperor, who paid attention to these phenomena, received the
+first announcement of it, he gave himself no rest until he had called
+a certain learned man and myself before him. As soon as I arrived, he
+anxiously asked me what I thought of such a sign; I asked time of him,
+in order to consider the aspects of the stars, and to discover the
+truth by their means, promising to acquaint him on the morrow; but the
+Emperor, persuaded that I wished to gain time, which was true, in
+order not to be obliged to announce anything fatal to him, said to me:
+'Go on the terrace of the palace and return at once to tell me what
+you have seen, for I did not see this star last evening, and you did
+not point it out to me; but I know that it is a comet; tell me what
+you think it announces to me.' Then scarcely allowing me time to say
+a word, he added: 'There is still another thing you keep back; it is
+that a change of reign and the death of a prince are announced by this
+sign.' And as I advanced the testimony of the prophet, who said: 'Fear
+not the signs of the heavens as the nations fear them,' the prince
+with his grand nature, and the wisdom which never forsook him, said,
+'We must not only fear Him who has created both us and this star. But
+as this phenomenon may refer to us, let us acknowledge it as a warning
+from Heaven."
+
+Louis le Debonnaire gave himself and his court to fasting and prayer,
+and built churches and monasteries. He died three years later, in 840,
+and historians have profited by this slight coincidence to prove that
+the appearance of the comet was a harbinger of death. The historian,
+Raoul Glader, added later: "These phenomena of the universe are never
+presented to man without surely announcing some wonderful and terrible
+event."
+
+Halley's comet again appeared in April, 1066, at the moment when
+William the Conqueror invaded England. It was pretended that it had
+the greatest influence on the fate of the battle of Hastings, which
+delivered over the country to the Normans.
+
+A contemporary poet, alluding probably to the English diadem with
+which William was crowned, had proclaimed in one place, "that the
+comet had been more favorable to William than nature had been to
+Caesar; the latter had no hair, but William had received some from the
+comet." A monk of Malmesbury apostrophized the comet in these terms:
+"Here thou art again, thou cause of the tears of many mothers! It is
+long since I have seen thee, but I see thee now, more terrible than
+ever; thou threatenest my country with complete ruin!"
+
+In 1455, the same comet made a more memorable appearance still. The
+Turks and Christians were at war, the West and the East seemed armed
+from head to foot--on the point of annihilating each other. The
+crusade undertaken by Pope Calixtus III. against the invading
+Saracens, was waged with redoubled ardor on the sudden appearance of
+the star with the flaming tail. Mahomet II. took Constantinople by
+storm, and raised the siege of Belgrade. But the Pope having put aside
+both the curse of the comet, and the abominable designs of the
+Mussulmans, the Christians gained the battle, and vanquished their
+enemies in a bloody fight. The _Angelus_ to the sound of bells dates
+from these ordinances of Calixtus III. referring to the comet.
+
+In his poem on astronomy, Daru, of the French Academy, describes this
+episode in eloquent terms:
+
+  "Un autre Mahomet a-t-il d'un bras puissant
+  Aux murs de Constantine arbore le croissant:
+  Le Danube etonne se trouble au bruit des armes,
+  La Grece est dans les fers, l'Europe est en alarmes;
+  Et pour comble d'horreur, l'astre au visage ardent
+  De ses ailes de feu va couvrir l'Occident.
+  Au pied de ses autels, qu'il ne saurait defendre,
+  Calixte, l'oeil en pleurs, le front convert de cendre,
+  Conjure la comete, objet de tant d'effroi:
+  Regarde vers les cieux, pontife, et leve-toi!
+  L'astre poursuit sa course, et le fer d'Huniade
+  Arrete le vainqueur, qui tombe sous Belgrade.
+  Dans les cieux cependant le globe suspendu,
+  Par la loi generale a jamais retenu,
+  Ignore les terreurs, l'existence de Rome,
+  Et la Terre peut-etre, et jusqu'au nom de l'homme,
+  De l'homme, etre credule, atome ambitieux,
+  Qui tremble sous un pretre et qui lit dans les cieux."
+
+This ancient comet witnessed many revolutions in human history, at
+each of its appearances, even in its later ones, in 1682, 1759, 1835;
+it was also presented to the Earth under the most diverse aspects,
+passing through a great variety of forms, from the appearance of a
+curved sabre, as in 1456, to that of a misty head, as in its last
+visit. Moreover, this is not an exception to the general rule, for
+these mysterious stars have had the gift of exercising a power on the
+imagination which plunged it in ecstasy or trouble. Swords of fire,
+bloody crosses, flaming daggers, spears, dragons, fish, and other
+appearances of the same kind, were given to them in the middle ages
+and the Renaissance.
+
+Comets like those of 1577 appear, moreover, to justify by their
+strange form the titles with which they are generally greeted. The
+most serious writers were not free from this terror. Thus, in a
+chapter on celestial monsters, the celebrated surgeon, Ambroise Pare,
+described the comet of 1528 under the most vivid and frightful colors:
+"This comet was so horrible and dreadful that it engendered such great
+terror to the people, that they died, some with fear, others with
+illness. It appeared to be of immense length, and of blood color; at
+its head was seen the figure of a curved arm, holding a large sword in
+the hand as if it wished to strike. At the point of the sword there
+were three stars, and on either side was seen a great number of
+hatchets, knives, and swords covered with blood, amongst which were
+numerous hideous human faces, with bristling beards and hair."
+
+The imagination has good eyes when it exerts itself. The great and
+strange variety of cometary aspects is described with exactitude by
+Father Souciet in his Latin poem on comets. "Most of them," says he,
+"shine with fires interlaced like thick hair, and from this they have
+taken the name of comets. One draws after it the twisted folds of a
+long tail; another appears to have a white and bushy beard; this one
+throws a glimmer similar to that of a lamp burning during the night;
+that one, O Titan! represents thy resplendent face; and this other, O
+Phoebe! the form of thy nascent horns. There are some which bristle
+with twisted serpents. Shall I speak of those armies which have
+sometimes appeared in the air? of those clouds which follow as it were
+along a circle, or which resemble the head of Medusa? Have there not
+often been seen figures of men or savage animals?
+
+"Often, in the gloom of night, lighted up by these sad fires, the
+horrible sound of arms is heard, the clashing of swords which meet in
+the clouds, the ether furiously resounding with fearful din which
+crush the people with terror. All comets have a melancholy light, but
+they have not all the same color. Some have a leaden color; others
+that of flame or brass. The fires of some have the redness of blood;
+others resemble the brightness of silver. Some again are azure; others
+have the dark and pale color of iron. These differences come from the
+diversity of the vapors which surround them, or from the different
+manner in which they receive the Sun's rays. Do you not see in our
+fires, that various kinds of wood produce different colors? Pines and
+firs give a flame mixed with thick smoke, and throw out little light.
+That which rises from sulphur and thick bitumen is bluish. Lighted
+straw gives out sparks of a reddish color. The large olive, laurel,
+ash of Parnassus, etc., trees which always retain their sap, throw a
+whitish light similar to that of a lamp. Thus, comets whose fires are
+formed of different materials, each take and preserve a color which is
+peculiar to them."
+
+Instead of being a cause of fear and terror, the variety and
+variability of the aspect of comets ought rather to indicate to us the
+harmlessness of their nature.
+
+[Illustration]
+
+
+
+
+THE TOTAL SOLAR ECLIPSE OF 1883
+
+_AN ASTRONOMERS VOYAGE TO FAIRY-LAND._
+
+(FROM THE ATLANTIC MONTHLY, MAY, 1890.)
+
+BY PROF. E.S. HOLDEN.
+
+
+[Illustration]
+
+In 1883 calculations showed that a solar eclipse of unusually long
+duration (5 minutes, 20 seconds) would occur in the South Pacific
+Ocean. The track of the eclipse lay south of the equator, but north of
+Tahiti. There were in fact only two dots of coral islands on the
+charts in the line of totality, Caroline Island, and one hundred and
+fifty miles west Flint Island (longitude 150 west, latitude 10 south).
+Almost nothing was known of either of these minute points. The station
+of the party under my charge (sent out by the United States government
+under the direction of the National Academy of Sciences) was to be
+Caroline Islands.
+
+Every inch of that island (seven miles long, a mile or so broad) is
+familiar now; but it is almost ludicrous to recollect with what
+anxiety we pored over the hydrographic charts and sailing instructions
+of the various nations, to find some information, however scanty,
+about the spot which was to be our home for nearly a month. All that
+was known was that this island had formerly been occupied as a guano
+station. There was a landing _then_.
+
+After the _personnel_ of the party had been decided on, there were the
+preparations for its subsistence to be looked out for. How to feed
+seventeen men for twenty-one days? Fortunately the provisions that we
+took, and the fresh fish caught for us by the natives, just sufficed
+to carry us through with comfort and with health.
+
+In March of 1883 we sailed from New York, and about the same time a
+French expedition left Europe bound for the same spot. From New York
+to Panama, from Panama to Lima, were our first steps. Here we joined
+the United States steamship Hartford, Admiral Farragut's flagship, and
+the next day set sail for our destined port,--if a coral reef
+surrounded by a raging surf can be called a port. About the same time
+a party of French observers under Monsieur Janssen, of the Paris
+Academy of Sciences, left Panama in the _Eclaireur_.
+
+[Illustration: BIRD'S EYE VIEW OF THE CAROLINE ISLANDS.]
+
+It was an ocean race of four thousand miles due west. The station
+Caroline Islands was supposed to be more desirable than Flint Island.
+Admiral Wilkes's expedition had lain off the latter several days
+without being able to land on account of the tremendous surf, so that
+it was eminently desirable to "beat the Frenchman," as the sailors put
+it. With this end in view our party had secured (through a member of
+the National Academy in Washington) the verbal promise of the proper
+official of the Navy Department that the Hartford's orders should read
+"to burn coal as necessary." The last obstacle to success was thus
+removed. We were all prepared, and now the ship would take us speedily
+to our station.
+
+Imagine our feelings the next day after leaving Callao, when the
+commanding officer of the Hartford opened his sealed orders. They read
+(dated Washington, in February), "To arrive at Caroline Islands (in
+April) with full coal-bunkers!"
+
+Officialism could go no further. Here was an expedition sent on a
+slow-sailing ship directly through the regions of calms for four
+thousand miles. It was of no possible use to send the expedition at
+all unless it arrived in time. And here were our orders "to arrive
+with full coal-bunkers."
+
+Fortunately we had unheard-of good-luck. The trade-wind blew for us as
+it did for the Ancient Mariner, and we sped along the parallel of 12 deg.
+south at the rate of one hundred and fifty miles a day under sail,
+while the _Eclaireur_ was steaming for thirty days a little nearer the
+equator in a dead calm. We arrived off the island just in time, with
+not a day to spare. It was a narrow escape, and a warning to all of us
+never to sail again under sealed orders unless we knew what was under
+the seal.
+
+Here we were, then, lying off the island and scanning its sparse crown
+of cocoanut palms, looking for a French flag among their wavy tufts.
+There was none in sight. We were the winners in the long race.
+Directly a whale-boat was lowered, and rowed around the white fringe
+of tremendous surf that broke ceaselessly against the vertical wall of
+coral rock. There was just one narrow place where the waves rolled
+into a sort of cleft and did not break. Here was the "landing," then.
+
+Landing was an acrobatic feat. In you went on the crest of a wave,
+pointing for the place where the blue seas did not break into white.
+An instant after, you were in the quiet water inside of the surf. Jump
+out everybody and hold the boat! Then it was pick up the various
+instruments, and carry them for a quarter of a mile to high-water mark
+and beyond, over the sharp points of the reef.
+
+In one night we were fairly settled; in another the Hartford had
+sailed away, leaving us in our fairy paradise, where the corals and
+the fish were of all the brilliant hues of the rainbow, and where the
+whiteness of the sand, the emerald of the lagoon, and the turquoise of
+the ocean made a picture of color and form never to be forgotten.
+
+But where are the Frenchmen? The next morning there is the _Eclaireur_
+lying a mile or so out, and there is a boat with the bo'sun--_maitre
+d'equipage_--pulling towards the surf. I wade out to the brink. He
+halloes:
+
+"Where is the landing, then?"
+
+"_Mais ici_"--Right here,--I say.
+
+"Yes, that's all very well for _persons_, but where do you land _les
+bagages_?"
+
+"_Mais ici_" I say again, and he says, "_Diable!_"
+
+But all the same he lands both persons and baggage in a neat,
+sailor-like way. In a couple of days our two parties of fifty persons
+had taken possession of this fairy isle. Observatories go up,
+telescopes, spectroscopes, photographic cameras are pointed and
+adjusted. The eventful day arrives. Everything is successful. Then
+comes the Hartford and takes us away, and a few days later comes the
+_Eclaireur_, and the Frenchmen are gone. The little island is left
+there, abandoned to the five natives who tend the sickly plantation of
+cocoa-palms, and live from year to year with no incident but the
+annual visit of "the blig" (Kanaka for brig), which brings their store
+of ship biscuit and molasses.
+
+[Illustration: "OBSERVATORIES GO UP."]
+
+Think of their stupendous experience! For years and years they have
+lived like that in the marvellous, continuous charm of the silent
+island. The "blig" had come and gone away this year, and there will
+be no more disturbance and discord for a twelve-month longer.
+
+  "Surely, surely, slumber is more sweet than toil, the shore
+  Than labor in the deep mid-ocean, wind, and wave, and oar,
+  Then rest ye, brother mariners, we will not wander more!"
+
+Not so! for here comes a great warship out of the East under a press
+of canvas. What event is this? See! she clews up her light sails and
+fires an eleven-inch gun! One of those guns of Mobile Bay. Then swarms
+out the starboard watch, one hundred and sixty strong, and a fleet of
+boats brings ashore these pale astronomers with those useless tubes
+that they point at the sky every night. But there are useful things
+too; cooking-stoves, and lumber, and bricks.
+
+What is all this? No sooner are these established than comes another
+ship and fires its gun! and another set of hardy sailormen pours out,
+and here is another party of madmen with tubes,--yes, and with
+cooking-stoves and lumber, too. Then comes the crowning, stupendous,
+and unspeakable event. The whole sun is hidden and the heavens are
+lighted up with pearly streamers! In the name of all the Polynesian
+gods, what is the meaning of all this?
+
+And then in a few days all these are gone. All the madmen. They have
+taken away the useless tubes, but they have left their houses
+standing. Their splendid, priceless, precious cook-stoves are here.
+See! here is a frying-pan! here are empty tin cans! and a keg of
+nails! They must have forgotten all this, madmen as they are!
+
+And the little island sinks back to its quiet and its calm. The lagoon
+lies placid like a mirror. The slow sea breaks eternally on the outer
+reef. The white clouds sail over day by day. The seabirds come back to
+their haunts,--the fierce man-of-war birds, the gentle, soft-eyed
+tern. But we, whose island home was thus invaded--are we the same? Was
+this a dream? Will it happen again next year? every year? What indeed
+was it that happened,--or in fact, did it happen at all? Is it not a
+dream, indeed?
+
+If we left those peaceful Kanakas to their dream, we Americans have
+brought ours away with us. Who will forget it? Which of us does not
+wish to be in that peaceful fairyland once more? That is the personal
+longing. But we have all come back, each one with his note-books full;
+and in a few weeks the stimulus of accustomed habit has taken
+possession of us again. Right and wrong are again determined by
+"municipal sanctions." We have become useful citizens once more.
+Perhaps it is just as well. We should have been poor poets, and we do
+not forget. So ends the astronomer's voyage to fairyland.
+
+[Illustration]
+
+
+
+
+HALOS--PARHELIA--THE SPECTRE OF THE BROCKEN, ETC
+
+(FROM THE ATMOSPHERE.)
+
+BY CAMILLE FLAMMARION.
+
+
+[Illustration]
+
+Treatises on meteorology have not, up to the present day, classified
+with sufficient regularity the divers optical phenomena of the air.
+Some of these phenomena have, however, been seen but rarely, and have
+not been sufficiently studied to admit of their classification. We
+have examined the common phenomenon of the rainbow and we have seen
+that it is due to the refraction and reflection of light on drops of
+water, and that it is seen upon the opposite side of the sky to the
+sun in day-time, or the moon at night. We are now about to consider an
+order of phenomena which are of rarer occurrence, but which have this
+property in common with the rainbow, viz., that they take place also
+upon the side of the sky opposite to the sun. These different optical
+effects are classed together under the name of _anthelia_ (from
+Greek, opposite to, and Greek, the sun). The optical phenomena which
+occur on the same side as, or around the sun, such as halos, parhelia,
+etc., will be dealt with later on.
+
+Before coming to the anthelia, properly so called, or to the colored
+rings which appear around a shadow, it is as well first to note the
+effects produced on the clouds and mists that are facing the sun when
+it rises or sets.
+
+Upon high mountains, the shadow of the mountain is often seen thrown
+either upon the surface of the lower mists or upon the neighboring
+mountains, and projected opposite to the sun almost horizontally. I
+once saw the shadow of the Righi very distinctly traced upon Mount
+Pilate, which is situated to the west of the Righi, on the other side
+of the Lake of Lucerne. This phenomenon occurs a few minutes after
+sunrise, and the triangular form of Righi is delineated in a shape
+very easy to recognize.
+
+The shadow of Mont Blanc is discerned more easily at sunset. MM.
+Bravais and Martins, in one of their scientific ascents, noticed it
+under specially favorable circumstances, the shadow being thrown upon
+the snow-covered mountains, and gradually rising in the atmosphere
+until it reached a height of 1 deg., still remaining quite visible. The
+air above the cone of the shadow was tinted with that rosy purple
+which is seen, in a fine sunset, coloring the lofty peaks. "Imagine,"
+says Bravais, "the other mountains also projecting, at the same
+moment, their shadows into the atmosphere, the lower parts dark and
+slightly greenish, and above each of these shadows the rosy surface,
+with the deeper rose of the belt which separates it from them; add to
+this the regular contour of the cones of the shadow, principally at
+the upper edge, and lastly, the laws of perspective causing all these
+lines to converge the one to the other toward the very summit of the
+shadow of Mont Blanc; that is to say, to the point of the sky where
+the shadows of our own selves were; and even then one will have but a
+faint idea of the richness of the meteorological phenomenon displayed
+before our eyes for a few instants. It seemed as though an invisible
+being was seated upon a throne surrounded by fire, and that angels
+with glittering wings were kneeling before him in adoration."
+
+Among the natural phenomena which now attract our attention, but fail
+to excite our surprise, there are some which possess the
+characteristics of a supernatural intervention. The names which they
+have received still bear witness to the terror which they once
+inspired; and even to-day, when science has stripped them of their
+marvellous origin, and explained the causes of their production, these
+phenomena have retained a part of their primitive importance, and are
+welcomed by the _savant_ with as much interest as when they were
+attributed to divine agency. Out of a large and very diverse number, I
+will first select the _Spectre of the Brocken_.
+
+The Brocken is the highest mountain in the picturesque Hartz chain,
+running through Hanover, being three hundred and thirty feet above the
+level of the sea.
+
+One of the best descriptions of this phenomenon is given by the
+traveller Hane, who witnessed it on the 23d of May, 1797. After having
+ascended no less than thirty miles to the summit, he had the good
+fortune at last to contemplate the object of his curiosity. The sun
+rose at about four o'clock, the weather being fine, and the wind
+driving off to the west the transparent vapors which had not yet had
+time to be condensed into clouds. About a quarter-past four, Hane saw
+in this direction a human figure of enormous dimensions. A gust of
+wind nearly blowing off his hat at that moment, he raised his hand to
+secure it, and the colossal figure imitated his action. Hane, noticing
+this, at once made a stooping movement, and this was also reproduced
+by the spectre. He then called another person to him, and placing
+themselves in the very spot where the apparition was first seen, the
+pair kept their eyes fixed on the Achtermannshohe, but saw nothing.
+After a short interval, however, two colossal figures appeared, which
+repeated the gestures made by them, and then disappeared.
+
+Some few years ago, in the summer of 1862, a French artist, M.
+Stroobant, witnessed and carefully sketched this phenomenon, which is
+drawn in full-page illustration, opposite p. 272. He had slept at the
+inn of the Brocken, and rising at two in the morning, he repaired to
+the plateau upon the summit in the company of a guide. They reached
+the highest point just as the first glimmer of the rising sun enabled
+them to distinguish clearly objects at a great distance. To use M.
+Stroobant's own words, "My guide, who had for some time appeared to be
+walking in search of something, suddenly led me to an elevation whence
+I had the singular privilege of contemplating for a few instants the
+magnificent effect of mirage, which is termed the Spectre of the
+Brocken. The appearance is most striking. A thick mist, which seemed
+to emerge from the clouds like an immense curtain, suddenly rose to
+the west of the mountain, a rainbow was formed, then certain
+indistinct shapes were delineated. First, the large tower of the inn
+was reproduced upon a gigantic scale; after that we saw our two selves
+in a more vague and less exact shape, and these shadows were in each
+instance surrounded by the colors of the rainbow, which served as a
+frame to this fairy picture. Some tourists who were staying at the inn
+had seen the sun rise from their windows, but no one had witnessed the
+magnificent spectacle which had taken place on the other side of the
+mountain."
+
+Sometimes these spectres are surrounded by colored concentric arcs.
+Since the beginning of the present century, treatises on meteorology
+designate, under the name of the _Ulloa circle_, the pale external
+arch which surrounds the phenomenon, and this same circle has
+sometimes been called the "white rainbow." But it is not formed at the
+same angular distance as the rainbow, and, although pale, it often
+envelops a series of interior colored arcs.
+
+[Illustration: "THE SPECTRE OF THE BROCKEN"]
+
+Ulloa, being in company with six fellow-travellers upon the Pambamarca
+at daybreak one morning, observed that the summit of the mountain was
+entirely covered with thick clouds, and that the sun, when it rose,
+dissipated them, leaving only in their stead light vapors, which it
+was almost impossible to distinguish. Suddenly, in the opposite
+direction to where the sun was rising, "each of the travellers beheld,
+at about seventy feet from where he was standing, his own image
+reflected in the air as in a mirror. The image was in the centre of
+three rainbows of different colors, and surrounded at a certain
+distance by a fourth bow with only one color. The inside color of each
+bow was carnation or red, the next shade was violet, the third yellow,
+the fourth straw color, the last green. All these bows were
+perpendicular to the horizon; they moved in the direction of, and
+followed, the image of the person they enveloped as with a glory." The
+most remarkable point was that, although the seven spectators were
+standing in a group, each person only saw the phenomenon in regard to
+his own person, and was disposed to disbelieve that it was repeated in
+respect to his companions. The extent of the bows increased
+continually and in proportion to the height of the sun; at the same
+time their colors faded away, the spectre became paler and more
+indistinct, and finally the phenomenon disappeared altogether. At the
+first appearance the shape of the bows was oval, but toward the end
+they became quite circular. The same apparition was observed in the
+polar regions by Scoresby, and described by him. He states that the
+phenomenon appears whenever there is mist and at the same time shining
+sun. In the polar seas, whenever a rather thick mist rises over the
+ocean, an observer, placed on the mast, sees one or several circles
+upon the mist.
+
+[Illustration: THE ULLOA CIRCLE.]
+
+These circles are concentric, and their common centre is in the
+straight line joining the eye of the observer to the sun, and extended
+from the sun toward the mist. The number of circles varies from one to
+five; they are particularly numerous and well colored when the sun is
+very brilliant and the mist thick and low. On July 23, 1821, Scoresby
+saw four concentric circles around his head. The colors of the first
+and of the second were very well defined; those of the third, only
+visible at intervals, were very faint, and the fourth only showed a
+slight greenish tint.
+
+The meteorologist Kaemtz has often observed the same fact in the Alps.
+Whenever this shadow was projected upon a cloud, his head appeared
+surrounded by a luminous aureola.
+
+To what action of light is this phenomenon due? Bouguer is of opinion
+that it must be attributed to the passage of light through icy
+particles. Such, also, is the opinion of De Saussure, Scoresby, and
+other meteorologists.
+
+In regard to the mountains, as we cannot assure ourselves directly of
+the fact by entering the clouds, we are reduced to conjecture. The
+aerostat traversing the clouds completely, and passing by the very
+point where the apparition is seen, affords one an opportunity of
+ascertaining the state of the cloud. This observation I have been able
+to make, and so to offer an explanation of the phenomenon.
+
+As the balloon sails on, borne forward by the wind, its shadow travels
+either on the ground or on the clouds. This shadow is, as a rule,
+black, like all others; but it frequently happens that it appears
+alone on the surface of the ground, and thus appears luminous.
+Examining this shadow by the aid of a telescope, I have noticed that
+it is often composed of a dark nucleus and a penumbra of the shape of
+an aureola. This aureola, frequently very large in proportion to the
+diameter of the central nucleus, eclipses it to the naked eye, so that
+the whole shadow appears like a nebulous circle projected in yellow
+upon the green ground of the woods and meadows. I have noticed, too,
+that this luminous shadow is generally all the more strongly marked in
+proportion to the greater humidity of the surface of the ground.
+
+Seen upon the clouds, this shadow sometimes presents a curious aspect.
+I have often, when the balloon emerged from the clouds into the clear
+sky, suddenly perceived, at twenty or thirty yards' distance, a second
+balloon distinctly delineated, and apparently of a grayish color,
+against the white ground of the clouds. This phenomenon manifests
+itself at the moment when the sun re-appears. The smallest details of
+the car can be made out clearly, and our gestures are strikingly
+reproduced by the shadow.
+
+[Illustration: THE SHADOW OF THE BALLOON WAS SEEN BY US.]
+
+On April 15, 1868, at about half-past three in the afternoon, we
+emerged from a stratum of clouds, when the shadow of the balloon was
+seen by us, surrounded by colored concentric circles, of which the car
+formed the centre. It was very plainly visible upon a yellowish white
+ground. A first circle of pale blue encompassed this ground and the
+car in a kind of ring. Around this ring was a second of a deeper
+yellow, then a grayish red zone, and lastly as the exterior
+circumference, a fourth circle, violet in hue, and imperceptibly
+toning down into the gray tint of the clouds. The slightest details
+were clearly discernible--net, robes, and instruments. Every one of
+our gestures was instantaneously reproduced by the aerial spectres.
+The anthelion remained upon the clouds sufficiently distinct, and for
+a sufficiently long time, to permit of my taking a sketch in my
+journal and studying the physical condition of the clouds upon which
+it was produced. I was able to determine directly the circumstances of
+its production. Indeed, as this brilliant phenomenon occurred in the
+midst of the very clouds which I was traversing, it was easy for me to
+ascertain that these clouds were not formed of frozen particles. The
+thermometer marked 2 deg. above zero. The hygrometer marked a maximum of
+humidity experienced, namely, seventy-seven at three thousand seven
+hundred and seventy feet, and the balloon was then at four thousand
+six hundred feet, where the humidity was only seventy-three. It is
+therefore certain that this is a phenomenon of the diffraction of
+light simply produced by the vesicles of the mist.
+
+The name of diffraction is given to all the modifications which the
+luminous rays undergo when they come in contact with the surface of
+bodies. Light, under these circumstances, is subject to a sort of
+deviation, at the same time becoming decomposed, whence result those
+curious appearances in the shadows of objects which were observed for
+the first time by Grimaldi and Newton.
+
+The most interesting phenomena of diffraction are those presented by
+_gratings_, as are technically denominated the systems of linear and
+very narrow openings situated parallel to one another and at very
+small intervals. A system of this kind may be realized by tracing with
+a diamond, for instance, on a pane of glass equidistant lines very
+close together. As the light would be able to pass in the interstices
+between the strokes, whereas it would be stopped in the points
+corresponding to those where the glass was not smooth, there is, in
+reality, an effect produced as if there were a series of openings very
+near to each other. A hundred strokes, about 1/25th of an inch in
+length, may thus be drawn without difficulty. The light is then
+decomposed in spectra, each overlapping the other. It is a phenomenon
+of this kind which is seen when we look into the light with the eye
+half closed; the eyelashes in this case, acting as a net-work or
+grating. These net-works may also be produced by reflection, and it is
+to this circumstance that are due the brilliant colors observed when a
+pencil of luminous rays is reflected on a metallic surface regularly
+striated.
+
+To the phenomena of gratings must be attributed, too, the colors,
+often so brilliant, to be seen in mother-of-pearl. This substance is
+of a laminated structure; so much so, that in carving it the different
+folds are often cut in such a way as to form a regular net-work upon
+the surface. It is, again, to a phenomenon of this sort that are due
+the rainbow hues seen in the feathers of certain birds, and sometimes
+in spiders' webs. The latter, although very fine, are not simple, for
+they are composed of a large number of pieces joined together by a
+viscous substance, and thus constitute a kind of net-work.
+
+If the sun is near the horizon, and the shadow of the observer falls
+upon the grass, upon a field of corn, or other surface covered with
+dew, there is visible an aureola, the light of which is especially
+bright about the head, but which diminishes from below the middle of
+the body. This light is due to the reflection of light by the moist
+stubble and the drops of dew. It is brighter about the head, because
+the blades that are near where the shadow of the head falls expose to
+it all that part of them which is lighted up, whereas those farther
+off expose not only the part which is lighted up, but other parts
+which are not, and this diminishes the brightness in proportion as
+their distance from the head increases. The phenomenon is seen
+whenever there is simultaneously mist and sun. This fact is easily
+verified upon a mountain. As soon as the shadow of a mountaineer is
+projected upon a mist, his head gives rise to a shadow surrounded by a
+luminous aureola.
+
+[Illustration: FOG-BOW SEEN FROM THE MATTERHORN.]
+
+_The Illustrated London News_ of July 8, 1871, illustrates one of
+these apparitions, "The Fog-Bow, seen from the Matterhorn," observed
+by E. Whymper in this celebrated region of the Alps. The observation
+was taken just after the catastrophe of July 14, 1865; and by a
+curious coincidence, two immense white aerial crosses projected into
+the interior of the external arc. These two crosses were no doubt
+formed by the intersection of circles, the remaining parts of which
+were invisible. The apparition was of a grand and solemn character,
+further increased by the silence of the fathomless abyss into which
+the four ill-fated tourists had just been precipitated.
+
+[Illustration]
+
+Other optical appearances of an analogous kind are manifested under
+different conditions. Thus, for instance, if any one, turning his back
+to the sun, looks into water, he will perceive the shadow of his head,
+but always very much deformed. At the same time he will see starting
+from this very shadow what seem to be luminous bodies, which dart
+their rays in all directions with inconceivable rapidity, and to a
+great distance. These luminous appearances--these aureola rays--have,
+in addition to the darting movement, a rapid rotary movement around
+the head.
+
+[Illustration]
+
+
+
+
+THE PLANET VENUS
+
+BY AGNES M. CLERKE.
+
+
+
+
+I.
+
+HESPERUS AND PHOSPHOR.
+
+
+[Illustration]
+
+The radiant planet that hangs on the skirts of dusk and dawn
+
+     "like a jewel in an Ethiop's ear,"
+
+has been known and sung by poets in all ages. Its supremacy over the
+remainder of the starry host is recognized in the name given it by the
+Arabs, those nomad watchers of the skies, for while they term the moon
+"El Azhar," "the Brighter One," and the sun and moon together "El
+Azharan," "the Brighter Pair," they call Venus "Ez Zahra," the bright
+or shining one _par excellence_, in which sense the same word is used
+to describe a flower. This "Flower of Night" is supposed to be no
+other than the white rose into which Adonis was changed by Venus in
+the fable which is the basis of all early Asiatic mythology. The
+morning and evening star is thus the celestial symbol of that union
+between earth and heaven in the vivifying processes of nature,
+typified in the love of the goddess for a mortal.
+
+The ancient Greeks, on the other hand, not unnaturally took the star,
+which they saw alternately emerging from the effulgence of the rising
+and setting sun, in the east and in the west, for two distinct bodies,
+and named it differently according to the time of its appearance. The
+evening star they called Hesperus, and from its place on the western
+horizon, fabled an earthly hero of that name, the son of Atlas, who
+from the slopes of that mountain on the verge of the known world used
+to observe the stars until eventually carried off by a mighty wind,
+and so translated to the skies. These divine honors were earned by his
+piety, wisdom, and justice as a ruler of men, and his name long shed a
+shimmering glory over those Hesperidean regions of the earth, where
+the real and unreal touched hands in the mystical twilight of the
+unknown.
+
+But the morning star shone with a different significance as the herald
+of the day, the torchbearer who lights the way for radiant Aurora on
+her triumphal progress through the skies. Hence he was called
+Eosphorus, or Phosphorus, the bearer of the dawn, translated into
+Latin as Lucifer, the Light-bearer. The son of Eos, or Aurora, and the
+Titan Astraeus, he was of the same parentage as the other multitude of
+the starry host, to whom a similar origin was ascribed, and from whom
+in Greek mythology he was evidently believed to differ only in the
+superior order of his brightness. Homer, who mentions the planet in
+the following passage:
+
+  "But when the star of Lucifer appeared,
+  The harbinger of light, whom following close,
+  Spreads o'er the sea the saffron-robed morn."
+
+                              (LORD DERBY'S "Iliad.")
+
+recognizes no distinction between those celestial nomads, the planets,
+"wandering stars," as the Arabs call them, which visibly change their
+position relatively to the other stars, and the latter, whose places
+on the sphere are apparently fixed and immutable. In this he and his
+compatriots were far behind the ancient Egyptians, who probably
+derived their knowledge from still earlier speculators in Asia, for
+they not only observed the movements of some at least of the planets,
+but believed that Mercury and Venus revolved as satellites round the
+sun, which in its turn circled round our lesser world. Pythagoras is
+said to have been the first to identify Hesperus with Phosphor, as the
+
+  "Silver planet both of eve and morn,"
+
+and by Plato the same fact is recognized. The other planets, all of
+which had, according to him, been originally named in Egypt and Syria,
+have each its descriptive title in his nomenclature. Thus the
+innermost, "the Star of Mercury," is called Stilbon, "the Sparkler,"
+Mars, Pyroeis, "the Fiery One," while Jupiter, the planet of the
+slowest course but one, is designated as Phaeton, and Saturn, the
+tardiest of all, Phaenon. These names were in later times abandoned in
+favor of those of the divinities to whom they were respectively
+dedicated, unalterably associated now with the days of the week, over
+which they have been selected to preside.
+
+The Copernican theory, which once and forever "brushed the cobwebs out
+of the sky," by clearing away the mists of pre-existing error, first
+completely explained the varying positions of the Shepherd's star,
+irradiating the first or last watch of night, according to her
+alternate function as the follower or precursor of the sun. As she
+travels on a path nearer to him by more than twenty-five and a half
+million miles than that of the earth, she is seen by us on each side
+of him in turn after passing behind or in front of him. The points at
+which her orbit expands most widely to our eyes--an effect of course
+entirely due to perspective, as her distance from the sun is not then
+actually increased--are called her eastern and western elongations;
+that at which she passes by the sun on the hither side her inferior,
+and on the farther side her superior conjunction. At both conjunctions
+she is lost to our view, since she accompanies the sun so closely as
+to be lost in his beams, rising and setting at the same time, and
+travelling with him in his path through the heavens during the day.
+When at inferior conjunction, or between us and the sun, she turns her
+dark hemisphere to us like the new moon, and would consequently be
+invisible in any case, but when in the opposite position, shows us her
+illuminated face, and is literally a day star, invisible only because
+effaced by the solar splendor. It is as she gradually separates from
+him, after leaving this latter position, circling over that half of
+her orbit which lies to the east of him, that she begins to come into
+view as an evening star, following him at a greater and greater
+distance, and consequently setting later, until she attains her
+greatest eastern elongation, divided from the sun about 45 deg. of his
+visible circuit through the heavens, and consequently remaining above
+the horizon for some four hours after him. From this point she again
+appears to draw nearer to him until she passes on his hither side in
+inferior conjunction, from which she emerges on the opposite side to
+the westward, and begins to shine as a morning star, preceding him on
+his track, at a gradually increasing distance, until attaining her
+greatest westward elongation, and finally completing her cycle by
+returning to superior conjunction once more in a period of about five
+hundred and eighty-four days.
+
+Venus is thus Hesperus or Vesper, the evening star, when following the
+sun as she passes from beyond him in superior conjunction to inferior
+conjunction where she is nearest to the earth. As she again leaves him
+behind in her course from this point to the opposite one of superior
+conjunction, she appears in her second aspect as Phosphorus or
+Lucifer, "the sun of morning," and herald of the day, shining as
+
+                          "The fair star
+  That gems the glittering coronet of morn."
+
+
+
+
+II.
+
+THE PHASES OF VENUS.
+
+
+But the changes in the aspect of Venus due to her varying positions in
+her orbit are not confined to those which cause her to oscillate with
+a pendulum movement eastward and westward from the sun. The discovery
+that she undergoes phases exactly like those of the moon, followed
+that of the existence of Jupiter's satellites as the second great
+result achieved by the use of the telescope in the hands of Galileo.
+The fact that the planets were intrinsically dark bodies revolving
+round the sun, and reflecting its light, as he and Copernicus had
+maintained, thus received a further ocular demonstration. The
+Florentine astronomer describes in a letter to a friend how the
+planet, after emerging from superior conjunction as a morning star,
+gradually loses her rotundity on the side remote from the luminary,
+changing first to a half sphere and then to a waning crescent; until,
+after passing through the stage of absolute extinction when
+intervening between us and the sun, she re-appears as a morning star,
+and undergoes the same series of transformations in inverse order. The
+revelation was indeed so novel and unexpected, that when the slight
+deformation of the planet's shape was first detected by him, he did
+not venture to announce it in plain terms but veiled it, according to
+the prevailing fashion of the time, under a Latin anagram. His
+celebrated sentence--
+
+  "Haec immatura a me jam frustra leguntur."
+
+("Those incomplete observations are as yet read by me in vain.")
+
+forms, by transposing the letters, the more definite statement,
+
+  "Cynthiae figuras aemulatur Mater Amorum."
+
+("The mother of the loves imitates the aspects of Diana.")
+
+that is to say, Venus vies with the phases of the moon. The discovery
+was an important one from its bearing on popular superstition ascribing
+to the planets special influences on human affairs, for since they were
+thus shown to transmit to us only borrowed light, belief in their
+beneficent or malefic powers over man's destinies received a rude shock.
+
+[Illustration: THE PHASES OP VENUS.]
+
+Galileo's announcement, published in September, 1610, when only a
+slight flattening of the planet's disk was visible, received absolute
+confirmation in the ensuing months, as she completed her full
+half-circle of change on February 24th of the following year, and
+consequently exhibited herself to him in all her varying aspects. It
+was the first time they had been looked upon by a human eye, since its
+unaided powers do not enable it to discern them, although one
+exception to this rule is said to have existed. This was the case of
+the Swiss mathematician Gauss, who, when a child, on being shown the
+crescent star through the telescope, exclaimed to his mother that it
+"was turned wrong"; the inference being that he recognized the
+reversal of the image in the field of the glass. If it were indeed so,
+he deserves to rank with the Siberian savage, who described the
+eclipses, or Jupiter's satellites; or the shoemaker of Breslau, who
+could see and declare the positions of those minute orbs.
+
+The phases exhibited to us by Venus are due to her moving in an orbit
+within that of the earth, at one side of which she is between us and
+the sun, while at the other this position is exactly reversed. We may
+compare her to a performer in a great celestial circus, lit by a
+central chandelier, and ourselves to spectators in an external ring,
+from which we see her at one time facing us with the light full on
+her, at the opposite point in complete shadow, and at the intermediate
+ones in varying degrees of illumination according to our changing
+views of her. The same illustration may serve to show why Venus is
+brightest, not when full, since she is then beyond the sun, and at the
+farthest possible point from us, but when she approaches us at
+inferior conjunction, more nearly by over one hundred and thirty
+million miles, and still shows us a crescent of her illuminated
+surface, before passing into the last phase of total obscuration. When
+actually nearest to us she is absolutely invisible, being then, like
+the new moon, between us and the sun. Her varying degrees of
+brilliancy, even when in the same phase, are thus accounted for by her
+alternate retreat from and advance towards us as she circles round the
+sun. Completing, as she does, her revolution in about seven months and
+a half, she would of course go through the whole series of her
+metamorphoses in that time, were the earth, from which we observe
+them, a fixed point. Their protraction instead, over a term of five
+hundred and eighty-four days, or more than nineteen months, is due to
+the simultaneous motion of the earth in the same direction, over her
+larger orbit in a longer period, causing the same relative position of
+the sister planet to recur only as often as she overtakes her in her
+career. Thus the hour and minute hands of a watch, moving at different
+rates of speed after meeting on the dial plate at twelve o'clock, will
+not again come together until five minutes past one, when the swifter
+paced of the two will have completed a revolution and a twelfth. But
+were we to retard the motion of the latter, reducing it to only twice
+that of its companion, they would always meet at the figure twelve, as
+it would exactly complete two circuits while the hour hand was
+performing one. Venus thus overtakes and passes the earth once in five
+hundred and eighty-four days, or nearly two and a half of her own
+years, constituting what is called her synodic period of apparent
+revolution as seen from this globe. She thus presents to us all the
+phases undergone by our own satellite during a lunar month, passing
+from new to full, and _vice versa_, through the various intervening
+gradations of form.
+
+The phases of Venus are amongst the most beautiful subjects for
+observation in a moderate telescope, as her silver bow, gradually
+brightening in the evening dusk, or fading in the dawn,
+
+  "On a bed of daffodil sky,"
+
+is, after the two greater luminaries that rule the day and night, the
+most brilliant object in the heavens.
+
+
+
+
+III.
+
+THE SILVER CROWN.
+
+
+The parallel between Venus and
+
+  "That orbed maiden with fire laden,
+   Whom mortals call the moon,"
+
+is carried a stage further. Most of us are familiar with the spectacle
+in which the Ancient Egyptians saw symbolized Horus on the lap of
+Isis, but which we more prosaically term "the old moon in the new
+moon's arms." The strongly illuminated half circle next the sun is
+then seen embracing with its horns a dusky sphere, contrasting with it
+as tarnished silver does with the newly burnished metal. The same
+phenomenon is occasionally, though very rarely, exhibited by Venus,
+while close to the sun at inferior injunction, when the shadowy form
+of the full orb is seen to shine dimly within her crescent with what
+is termed "the ashen light." More wonderful still, this "glimmering
+sphere" is then crowned, as with a silver halo, by a thin luminous
+arch, forming a secondary sickle facing the one nearest the sun, and
+doubtless due to the refraction of his rays round the globe of the
+planet, through the upper regions of her twilight atmosphere. This
+spectacle was first observed by the Jesuit Ricciolo, an opponent of
+the Copernican theory, on January 9th, 1643. He describes the planet
+as ruddy near the sun, yellowish in the middle, and of greenish blue
+on the side remote from the sun; while he also noted the bow of light
+limiting the dark hemisphere. Scarcely daring to trust his own
+eyesight, he ascribed these appearances, although he recorded them, to
+illusory reflection in the telescope.
+
+[Illustration: VENUS AT HER GREATEST BRILLIANCY.]
+
+They were again seen, however, by Derham about 1715, and six years
+later by Kirch, in Berlin, who has the following entry in his diary
+for Saturday, June 29, 1721:--"I found Venus in a region where the sky
+was not very clear. The planet was narrow, and I seemed to see its
+dark side, though this is almost incredible. The diameter of Venus was
+65", and its sickle seemed to tremble in the atmospheric vapors."
+Again, on March 8th, 1726, he records a similar observation. "We
+observed Venus with the twenty-six foot telescope. I perceived her
+dark side, and its edge seemed to describe a smaller circle than that
+of the light side, as is the case of the moon." This effect is due to
+irradiation, that is to say, to the glare from a bright surface,
+giving a deceptive enlargement to its apparent area. He again saw the
+dark side of the planet in October, 1759, as did Harding at Goettingen,
+with Herschel's ten-foot reflector, on January 24th, 1806. This latter
+observer saw it on this occasion stand out against the background of
+the sky as of a pale ashen green, while on February 28th following, it
+seemed to him of a pale reddish gray, like the color of the eclipsed
+moon.
+
+That the latter body should send to us from her nocturnal shadows
+sufficient light to be visible is easily explicable, since she is then
+flooded with earth-light reflected on her from a surface thirteen and
+one-half times greater than her own, and probably casting on her an
+illumination transcending our full moonlight in the same proportion.
+But the secondary light of Venus admits of no such explanation, since
+earth-light on her surface, diminished by 1/12000th part compared to
+what it is on that of the moon, would be quite insufficient to render
+her visible to our eyes. The phenomenon was therefore adduced as an
+argument for the habitability of the planets by Gruithuisen, of the
+Munich Observatory, who, writing early in this century, suggested that
+the ashen light of Venus might be due to general illuminations in
+celebration by her inhabitants of some periodically recurring
+festivity, The materials for a flare-up on so grand a scale would, he
+thought, exist in abundance, as he conjectured the vegetation of our
+planetary neighbor to be more luxuriant than that of our Brazilian
+forests. The phosphorescence of the Aphroditean oceans, warm and
+teeming with life, as they are held to be by Zollner, was advanced as
+an explanatory hypothesis, with scarcely more plausibility, by
+Professor Safarik, while others have resorted to the supposition of
+atmospheric or electrical luminosity producing on a large scale some
+such display as that of the aurora borealis.
+
+Professor Vogel, of Berlin, who himself saw part of the night-side of
+Venus, in its semi-obscurity in November, 1871, ascribed its
+visibility to a twilight effect caused by a very extensive atmosphere.
+The light thus transmitted to us by aerial diffusion and giving the
+ashen light, is reflected sunlight, while that sent by the luminous
+arc on its edge is direct sunlight, refracted, or bent round to us,
+from behind the planet. The silver selvedge of the dawn edging the
+dark limb may consequently be the brightest part of the broken nimbus
+that then seems to surround her.
+
+A similar appearance is observed during transits of Venus, when she
+passes directly between us and the actual solar disk. A silver thread
+is then seen encircling that side of the planet which has not yet
+entered on the face of the sun or "a shadowy nebulous ring," as it was
+described by Mr. Macdonnell at Eden, surrounds the whole planetary
+disk when two-thirds of it have passed the solar edge. As it moves off
+it, the same aureole again becomes visible, testifying to the
+existence of an atmosphere of considerable extent exterior to the
+sharply outlined surface ordinarily visible. The shimmering haze of
+reflected sunlight which perpetually enfolds her is only made apparent
+to us under exceptional circumstances which cut off some portion of
+her more immediate light, just as we see the motes in the air
+illuminated by a candle if we hide the actual flame from our eyes. The
+perennial twilight which seems to reign over the nocturnal hemisphere
+of Venus may compensate, perhaps, for the want of a satellite to
+modify its darkness.
+
+The great prolongation at other times of the horns of her crescent, so
+as to embrace almost her entire circumference with a tenuous ring of
+light, is doubtless due to the same cause, as their visibility should
+otherwise be limited to a half segment of a circle. The regions thus
+shining to us are obviously those on which the sun has not yet set,
+his appearance above the horizon being prolonged, as in our own case,
+by refraction, though to a much larger extent. The magnitude of the
+sun's disk as seen from Venus, a third larger than it appears to us,
+is also adducted by Mr. Proctor in his posthumous work, "The Old and
+the New Astronomy," edited and completed by Mr. A.C. Ranyard, as an
+element in extending the illumination of Venus to more than a
+hemisphere of her surface. As his diameter there is 44-1/4 deg., a zone
+of more than 22 deg. wide outside the sunward hemisphere is he thinks
+illuminated by direct though partial sunlight, the orb being
+throughout this tract still partially above the horizon.
+
+[Illustration: GEOGRAPHICAL ASPECT OF VENUS.]
+
+
+
+
+[Illustration]
+
+
+THE STARS
+
+(FROM STARLAND.)
+
+BY SIR ROBERT S. BALL.
+
+
+[Illustration]
+
+The group of bodies which cluster around our sun forms a little
+island, so to speak, in the extent of infinite space. We may
+illustrate this by a map in which we shall endeavor to show the stars
+placed at their proper relative distances. We first open the compasses
+one inch, and thus draw a little circle to represent the path of the
+earth. We are not going to put in all the planets. We take Neptune,
+the outermost, at once. To draw its path I open the compasses to
+thirty inches, and draw a circle with that radius. That will do for
+our solar system, though the comets no doubt will roam beyond these
+limits. To complete our map we ought of course to put in some stars.
+There are a hundred million to choose from, and we shall begin with
+the brightest. It is often called the Dog Star, but astronomers know
+it better as Sirius. Let us see where it is to be placed on our map.
+Sirius is beyond Neptune, so it must be outside somewhere. Indeed, it
+is a good deal further off than Neptune; so I try at the edge of the
+drawing-board; I have got a method of making a little calculation that
+I do not intend to trouble you with, but I can assure you that the
+results it leads me to are quite correct; they show me that this board
+is not big enough. But could a board which was big enough fit into
+this lecture theatre? Here, again, I make my little calculations, and
+I find that there would not be room for a board sufficiently great; in
+fact, if I put the sun here at one end, with its planets around it?
+Sirius would be too near on the same scale if it were at the further
+corner. The board would have to go out through the wall of the
+theatre, out through London. Indeed, big as London is, it would not be
+large enough to contain the drawing-board that I should require. It
+would have to stretch about twenty miles from where we are now
+assembled. We may therefore dismiss any hope of making a practical map
+of our system on this scale if Sirius is to have its proper place. Let
+us, then, take some other star. We shall naturally try with the
+nearest of all. It is one that we do not know in this part of the
+world, but those that live in the southern hemisphere are well
+acquainted with it. The name of this star is Alpha Centauri. Even for
+this star we should require a drawing three or four miles long if the
+distance from the earth to the sun is to be taken as one inch. You see
+what an isolated position our sun and his planets occupy. The members
+of the family are all close together, and the nearest neighbors are
+situated at enormous distances. There is a good reason for this
+separation. The stars are very pretty and perfectly harmless to us
+where they are at present situated. They might be very troublesome
+neighbors if they were very much closer to our system. It is therefore
+well they are so far off; they would be constantly making disturbances
+in the sun's family if they were near at hand. Sometimes they would be
+dragging us into unpleasantly great heat by bringing us too close to
+the sun, or producing a coolness by pulling us away from the sun,
+which would be quite as disagreeable.
+
+
+The Stars are Suns.
+
+We are about to discuss one of the grandest truths in the whole of
+nature. We have had occasion to see that this sun of ours is a
+magnificent globe immensely larger than the greatest of his planets,
+while the greatest of these planets is immensely larger than this
+earth; but now we are to learn that our sun is, indeed, only a star
+not nearly so bright as many of those which shine over our heads every
+night. We are comparatively close to the sun, so that we are able to
+enjoy his beautiful light and cheering heat. Each of those other
+myriads of stars is a sun, and the splendor of those distant suns is
+often far greater than that of our own. We are, however, so enormously
+far from them that they appear dwindled down to insignificance. To
+judge impartially between our sun or star and such a sun or star as
+Sirius we should stand halfway between the two; it is impossible to
+make a fair estimate when we find ourselves situated close to one star
+and a million times as far from the other. After allowance is made for
+the imperfections of our point of view, we are enabled to realize the
+majestic truth that the sun is no more than a star, and that the other
+stars are no less than suns. This gives us an imposing idea of the
+extent and magnificence of the universe in which we are situated. Look
+lip at the sky at night--you will see a host of stars; try to think
+that every one of them is itself a sun. It may probably be that those
+suns have planets circling round them, but it is hopeless for us to
+expect to see such planets. Were you standing on one of those stars
+and looking towards our system, you would not perceive the sun to be
+the brilliant and gorgeous object that we know so well. If you could
+see him at all, he would merely seem like a star, not nearly as bright
+as many of those you can see at night. Even if you had the biggest of
+telescopes to aid your vision, you could never discern from one of
+these bodies the planets which surround the sun, no astronomer in the
+stars could see Jupiter, even if his sight were a thousand times as
+powerful as any sight or telescope that we know. So minute an object
+as our earth would, of course, be still more hopelessly beyond the
+possibility of vision.
+
+
+The Number of the Stars.
+
+To count the stars involves a task which lies beyond the power of man
+to accomplish. Even without the aid of any telescope, we can see a
+great multitude of stars from this part of the world. There are also
+many constellations in the southern hemisphere which never appear
+above our horizon. If, however, we were to go to the equator, then, by
+waiting there for a twelve-month, all the stars in the heavens would
+have been successively exposed to view. An astronomer, Houzeau, with
+the patience to count them, enumerated about six thousand. This is the
+naked-eye estimate of the star-population of the heavens; but if
+instead of relying on unaided vision, you get the assistance of a
+little telescope, you will be astounded at the enormous multitude of
+stars which are disclosed.
+
+[Illustration: FIG 1. THE GREAT BEAR AND THE POLE.]
+
+An ordinary opera-glass or binocular is a very useful instrument for
+looking at the stars in the heavens. If you employ an instrument of
+this sort, you will be amazed to find that the heavens teem with
+additional hosts of stars that your unaided vision would never have
+given you knowledge of. Any part of the sky may be observed; but, just
+to give an illustration, I shall take one special region, namely, that
+of the Great Bear (Fig. 1). The seven well-known stars are here shown,
+four of which form a sort of oblong, while the other three represent
+the tail. I would like you to make this little experiment. On a fine
+clear night, count how many stars there are within this oblong; they
+are all very faint, but you will be able to see a few, and, with good
+sight, and on a clear night, you may see perhaps ten. Next take your
+opera-glass and sweep it over the same region; if you will carefully
+count the stars it shows, you will find fully two hundred; so that
+the opera-glass has, in this part of the sky, revealed nearly twenty
+times as many stars as could be seen without its aid. As six thousand
+stars can be seen by the eye all over the heavens, we may fairly
+expect that twenty times that number--that is to say, one hundred and
+twenty thousand stars--could be shown by the opera-glass over the
+entire sky. Let us go a step further, and employ a telescope, the
+object-glass of which is three inches across. This is a useful
+telescope to have, and, if a good one, will show multitudes of
+pleasing objects, though an astronomer would not consider it very
+powerful. An instrument like this, small enough to be carried in the
+hand, has been applied to the task of enumerating the stars in the
+northern half of the sky, and three hundred and twenty thousand stars
+were counted. Indeed, the actual number that might have been seen with
+it is considerably greater, for when the astronomer Argelander made
+this memorable investigation he was unable to reckon many of the stars
+in localities where they lay very close together. This grand count
+only extended to half the sky, and, assuming that the other half is as
+richly inlaid with stars, we see that a little telescope like that we
+have supposed will, when swept over the heavens, reveal a number of
+stars which exceeds that of the population of any city in England
+except London. It exhibits more than one hundred times as many stars
+as our eyes could possibly reveal. Still, we are only at the beginning
+of the count; the very great telescopes add largely to the number.
+There are multitudes of stars which in small instruments we cannot
+see, but which are distinctly visible from our great observatories.
+That telescope would be still but a comparatively small one which
+would show as many stars in the sky as there are people living in the
+mighty city of London; and with the greatest instruments, the tale of
+stars has risen to a number far greater than that of the entire
+population of Great Britain.
+
+In addition to those stars which the largest telescopes show us, there
+are myriads which make their presence evident in a wholly different
+way. It is only in quite recent times that an attempt has been made to
+develop fully the powers of photography in representing the celestial
+objects. On a photographic plate which has been exposed to the sky in
+a great telescope the stars are recorded by thousands. Many of these
+may, of course, be observed with a good telescope, but there are not a
+few others which no one ever saw in a telescope, which apparently no
+one ever could see, though the photograph is able to show them. We do
+not, however, employ a camera like that which the photographer uses
+who is going to take your portrait. The astronomer's plate is put into
+his telescope, and then the telescope is turned towards the sky. On
+that plate the stars produce their images, each by its own light. Some
+of these images are excessively faint, but we give a very long
+exposure of an hour or two hours; sometimes as much as four hours'
+exposure is given to a plate so sensitive that a mere fraction of a
+second would sufficiently expose it during the ordinary practice of
+taking a photograph in daylight. We thus afford sufficient time to
+enable the fainter objects to indicate their presence upon the
+sensitive film. Even with an exposure of a single hour a picture
+exhibiting sixteen thousand stars has been taken by Mr. Isaac Roberts,
+of Liverpool. Yet the portion of the sky which it represents is only
+one ten-thousandth part of the entire heavens. It should be added that
+the region which Mr. Roberts has photographed is furnished with stars
+in rather exceptional profusion.
+
+Here, at last, we have obtained some conception of the sublime scale
+on which the stellar universe is constructed. Yet even these plates
+cannot represent all the stars that the heavens contain. We have every
+reason for knowing that with larger telescopes, with more sensitive
+plates, with more prolonged exposures, ever fresh myriads of stars
+will be brought within our view.
+
+You must remember that every one of these stars is truly a sun, a
+lamp, as it were, which doubtless gives light to other objects in its
+neighborhood as our sun sheds light upon this earth and the other
+planets. In fact, to realize the glories of the heavens you should try
+to think that the brilliant points you see are merely the luminous
+points of the otherwise invisible universe.
+
+Standing one fine night on the deck of a Cunarder we passed in open
+ocean another great Atlantic steamer. The vessel was near enough for
+us to see not only the light from the mast-head but also the little
+beams from the several cabin ports; and we could see nothing of the
+ship herself. Her very existence was only known to us by the twinkle
+of these lights. Doubtless her passengers could see, and did see, the
+similar lights from our own vessel, and they probably drew the correct
+inference that these lights indicated a great ship.
+
+Consider the multiplicity of beings and objects in a ship: the
+captain and the crew, the passengers, the cabins, the engines, the
+boats, the rigging, and the stores. Think of all the varied interests
+there collected and then reflect that out on the ocean, at night, the
+sole indication of the existence of this elaborate structure was given
+by the few beams of light that happened to radiate from it. Now raise
+your eyes to the stars; there are the twinkling lights. We cannot see
+what those lights illuminate, we can only conjecture what untold
+wealth of non-luminous bodies may also lie in their vicinity; we may,
+however, feel certain that just as the few gleaming lights from a ship
+are utterly inadequate to give a notion of the nature and the contents
+of an Atlantic steamer, so are the twinkling stars utterly inadequate
+to give even the faintest conception of the extent and the interest of
+the universe. We merely see self-luminous bodies, but of the
+multitudes of objects and the elaborate systems of which these bodies
+are only the conspicuous points we see nothing and we know very
+little. We are, however, entitled to infer from an examination of our
+own star--the sun--and of the beautiful system by which it is
+surrounded, that these other suns may be also splendidly attended.
+This is quite as reasonable a supposition as that a set of lights seen
+at night on the Atlantic Ocean indicates the existence of a fine ship.
+
+
+The Clusters of Stars.
+
+On a clear night you can often see, stretching across the sky, a track
+of faint light, which is known to astronomers as the "Milky Way." It
+extends below the horizon, and then round the earth to form a girdle
+about the heavens. When we examine the Milky Way with a telescope we
+find, to our amazement, that it consists of myriads of stars, so small
+and so faint that we are not able to distinguish them individually; we
+merely see the glow produced from their collective rays. Remembering
+that our sun is a star, and that the Milky Way surrounds us, it would
+almost seem as if our sun were but one of the host of stars which form
+this cluster.
+
+There are also other clusters of stars, some of which are exquisitely
+beautiful telescopic spectacles. I may mention a celebrated pair of
+these objects which lies in the constellation of Perseus. The sight of
+them in a great telescope is so imposing that no one who is fit to
+look through a telescope could resist a shout of wonder and admiration
+when first they burst on his view. But there are other clusters. Here
+is a picture of one which is known as the "Globular Cluster in the
+Centaur" (Fig. 2). It consists of a ball of stars, so far off that,
+however large these several suns may actually be, they have dwindled
+down to extremely small points of light. A homely illustration may
+serve to show the appearance which a globular cluster presents in a
+good telescope. I take a pepper-caster, and on a sheet of white paper
+I begin to shake out the pepper until there is a little heap at the
+centre and other grains are scattered loosely about. Imagine that
+every one of those grains of pepper was to be transformed into a tiny
+electric light, and then you have some idea of what a cluster of stars
+would look like when viewed through a telescope of sufficient power.
+There are multitudes of such groups scattered through the depths of
+space. They require our biggest telescopes to show them adequately. We
+have seen that our sun is a star, being only one of a magnificent
+cluster that forms the Milky Way. We have also seen that there are
+other groups scattered through the length and depth of space. It is
+thus we obtain a notion of the rank which our earth holds in the
+scheme of things celestial.
+
+[Illustration: FIG. 2. GLOBULAR CLUSTER IN THE CENTAUR.]
+
+
+The Rank of the Earth as a Globe in Space.
+
+Let me give an illustration with the view of explaining more fully the
+nature of the relation which the earth bears to the other globes which
+abound through space, and you must allow me to draw a little upon my
+imagination. I shall suppose that the mails of our country extend not
+only over this globe, but that they also communicate with other
+worlds; that postal arrangements exist between Mars and the earth,
+between the sun and Orion--in fact, everywhere throughout the whole
+extent of the universe. We shall consider how our letters are to be
+addressed. Let us take the case of Mr. John Smith, merchant, who lives
+at 1001, Piccadilly; and let us suppose that Mr. John Smith's business
+transactions are of such an extensive nature that they reach not only
+all over this globe, but away throughout space. I shall suppose that
+the firm has a correspondent residing--let us say in the constellation
+of the Great Bear; and when this man of business wants to write to Mr.
+Smith from these remote regions, what address must he put upon the
+letter, so that the Postmaster-General of the universe shall make no
+mistake about its delivery? He will write as follows:--
+
+  MR. JOHN SMITH,
+    1001 Piccadilly,
+      London,
+        England,
+          Europe,
+            Earth,
+              Near the Sun,
+                Milky Way,
+                  The Universe.
+
+Let us now see what the several lines of this address mean. Of course
+we put down the name of Mr. John Smith in the first line, and then we
+will add "1001 Piccadilly" for the second; but as the people in the
+Great Bear are not likely to know where Piccadilly is, we shall add
+"London" underneath. As even London itself cannot be well known
+everywhere, it is better to write "England." This would surely find
+Mr. John Smith from any post-office on this globe. From other globes,
+however, the supreme importance of England may not be so immediately
+recognized, and therefore it is as well to add another line, "Europe."
+This ought to be sufficient, I think, for any post-office in the solar
+system. Europe is big enough to be visible from Mars or Venus, and
+should be known to the post-office people there, just as we know and
+have names for the continents on Mars. But further away there might be
+a little difficulty; from Uranus and Neptune the different regions on
+our earth can never have been distinguished, and therefore we must add
+another line to indicate the particular globe of the solar system
+which contains Europe. Mark Twain tells us that there was always one
+thing in astronomy which specially puzzled him, and that was to know
+how we found out the names of the stars. We are, of course, in
+hopeless ignorance of the name by which this earth is called among
+other intelligent beings elsewhere who can see it. I can only adopt
+the title of "Earth," and therefore I add this line. Now our address
+is so complete that from anywhere in the solar system--from Mercury,
+from Jupiter, or Neptune--there ought to be no mistake about the
+letter finding its way to Mr. John Smith. But from his correspondent
+in the Great Bear this address would be still incomplete; they cannot
+see our earth from there, and even the sun himself only looks like a
+small star--like one, in fact, of thousands of stars elsewhere.
+However, each star can be distinguished, and our sun may, for
+instance, be recognized from the Great Bear by some designation. We
+shall add the line "Near the Sun," and then I think that from this
+constellation, or from any of the other stars around us, the address
+of Mr. John Smith may be regarded as complete. But Mr. Smith's
+correspondence may be still wider. He may have an agent living in the
+cluster of Perseus or on some other objects still fainter and more
+distant; then "Near the Sun" is utterly inadequate as a concluding
+line to the address, for the sun, if it can be seen at all from
+thence, will be only of the significance of an excessively minute
+star, no more to be designated by a special name than are each of the
+several leaves on the trees of a forest. What this distant
+correspondent will be acquainted with is not the earth or the sun but
+only the cluster of stars among which the sun is but a unit. Again we
+use our own name to denote the cluster, and we call it the "Milky
+Way." When we add this line, we have made the address of Mr. John
+Smith as complete as circumstances will permit. I think a letter
+posted to him anywhere ought to reach its destination. To perfect it,
+however, we will finish up with one line more--"The Universe."
+
+
+The Distances of the Stars.
+
+I must now tell you something about the distances of the stars. I
+shall not make the attempt to explain fully how astronomers make such
+measurements, but I will give you some notion of how it is done. You
+may remember I showed you how we found the distance of a globe that
+was hung from the ceiling. The principle of the method for finding the
+distance of a star is somewhat similar, except that we make the two
+observations not from the two ends of a table, not even from opposite
+sides of the earth, but from two opposite points on the earth's orbit,
+which are therefore at a distance of one hundred and eighty-six
+million miles. Imagine that on Midsummer Day, when standing on the
+earth here, I measure with a piece of card the angle between the star
+and the sun. Six months later, on Midwinter Day, when the earth is at
+the opposite point of its orbit, I again measure the angle between the
+same star and the sun, and we can now determine the star's distance by
+making a triangle. I draw a line a foot long, and we will take this
+foot to represent one hundred and eighty-six million miles, the
+distance between the two stations; then placing the cards at the
+corners, I rule the two sides and complete the triangle, and the star
+must be at the remaining corner; then I measure the sides of the
+triangle, and how many feet they contain, and recollecting that each
+foot corresponds to one hundred and eighty-six million miles, we
+discover the distance of the star. If the stars were comparatively
+near us, the process would be a very simple one; but, unfortunately,
+the stars are so extremely far off that this triangle, even with a
+base of only one foot, must have its sides many miles long. Indeed,
+astronomers will tell you that there is no more delicate or
+troublesome work in the whole of their science than that of
+discovering the distance of a star.
+
+In all such measurements we take the distance from the earth to the
+sun as a conveniently long measuring-rod, whereby to express the
+results. The nearest stars are still hundreds of thousands of times as
+far off as the sun. Let us ponder for a little on the vastness of
+these distances. We shall first express them in miles. Taking the
+sun's distance to be ninety-three million miles, then the distance of
+the nearest fixed star is about twenty millions of millions of
+miles--that is to say, we express this by putting down a 2 first, and
+then writing thirteen ciphers after it. It is, no doubt, easy to speak
+of such figures, but it is a very different matter when we endeavor to
+imagine the awful magnitude which such a number indicates. I must try
+to give some illustrations which will enable you to form a notion of
+it. At first I was going to ask you to try and count this number, but
+when I found it would require at least three hundred thousand years,
+counting day and night without stopping, before the task was over, it
+became necessary to adopt some other method.
+
+When on a visit in Lancashire I was once kindly permitted to visit a
+cotton mill, and I learned that the cotton yarn there produced in a
+single day would be long enough to wind round this earth twenty-seven
+times at the equator. It appears that the total production of cotton
+yarn each day in all the mills together would be on the average about
+one hundred and fifty-five million miles. In fact, if they would only
+spin about one-fifth more, we could assert that Great Britain produced
+enough cotton yarn every day to stretch from the earth to the sun and
+back again! It is not hard to find from these figures how long it
+would take for all the mills in Lancashire to produce a piece of yarn
+long enough to reach from our earth to the nearest of the stars. If
+the spinners worked as hard as ever they could for a year, and if all
+the pieces were then tied together, they would extend to only a small
+fraction of the distance; nor if they worked for ten years, or for
+twenty years, would the task be fully accomplished. Indeed, upwards of
+four hundred years would be necessary before enough cotton could be
+grown in America and spun in this country to stretch over a distance
+so enormous. All the spinning that has ever yet been done in the world
+has not formed a long enough thread!
+
+There is another way in which we can form some notion of the immensity
+of these sidereal distances. You will recollect that, when we were
+speaking of Jupiter's moons, I told you of the beautiful discovery
+which their eclipses enabled astronomers to make. It was thus found
+that light travels at the enormous speed of about one hundred and
+eighty-five thousand miles per second. It moves so quickly that within
+a single second a ray would flash two hundred times from London to
+Edinburgh and back again.
+
+We said that a meteor travels one hundred times as swiftly as a
+rifle-bullet; but even this great speed seems almost nothing when
+compared with the speed of light, which is ten thousand times as
+great. Suppose some brilliant outbreak of light were to take place in
+a distant star--an outbreak which would be of such intensity that the
+flash from it would extend far and wide throughout the universe. The
+light would start forth on its voyage with terrific speed. Any
+neighboring star which was at a distance of less than one hundred and
+eighty-five thousand miles would, of course, see the flash within a
+second after it had been produced. More distant bodies would receive
+the intimation after intervals of time proportioned to their
+distances. Thus, if a body were one million miles away, the light
+would reach it in from five to six seconds, while over a distance as
+great as that which separates the earth from the sun the news would be
+carried in about eight minutes. We can calculate how long a time must
+elapse ere the light shall travel over a distance so great as that
+between the star and our earth. You will find that from the nearest of
+the stars the time required for the journey will be over three years.
+Ponder on all that this involves. That outbreak in the star might be
+great enough to be visible here, but we could never become aware of it
+till three years after it had happened. When we are looking at such a
+star to-night we do not see it as it is at present, for the light that
+is at this moment entering our eyes has travelled so far that it has
+been three years on the way. Therefore, when we look at the star now
+we see it as it was three years previously. In fact, if the star were
+to go out altogether, we might still continue to see it twinkling for
+a period of three years longer, because a certain amount of light was
+on its way to us at the moment of extinction, and so long as that
+light keeps arriving here, so long shall we see the star showing as
+brightly as ever. When, therefore, you look at the thousands of stars
+in the sky to-night, there is not one that you see as it is now, but
+as it was years ago.
+
+I have been speaking of the stars that are nearest to us, but there
+are others much farther off. It is true we cannot find the distances
+of these more remote objects with any degree of accuracy, but we can
+convince ourselves how great that distance is by the following
+reasoning. Look at one of the brightest stars. Try to conceive that
+the object was carried away further into the depths of space, until it
+was ten times as far from us as it is at present, it would still
+remain bright enough to be recognized in quite a small telescope; even
+if it were taken to one hundred times its original distance it would
+not have withdrawn from the view of a good telescope; while if it
+retreated one thousand times as far as it was at first it would still
+be a recognizable point in our mightiest instruments. Among the stars
+which we can see with our telescopes, we feel confident there must be
+many from which the light has expended hundreds of years, or even
+thousands of years, on the journey. When, therefore, we look at such
+objects, we see them, not as they are now, but as they were ages ago;
+in fact, a star might have ceased to exist for thousands of years, and
+still be seen by us every night as a twinkling point in our great
+telescopes.
+
+Remembering these facts, you will, I think, look at the heavens with a
+new interest. There is a bright star, Vega, or Alpha Lyrae, a beautiful
+gem, so far off that the light from it which now reaches our eyes
+started before many of my audience were born. Suppose that there are
+astronomers residing on worlds amid the stars, and that they have
+sufficiently powerful telescopes to view this globe, what do you think
+they would observe? They will not see our earth as it is at present;
+they will see it as it was years (and sometimes many years) ago. There
+are stars from which if England could now be seen, the whole of the
+country would be observed at this present moment to be in a great
+state of excitement at a very auspicious event. Distant astronomers
+might notice a great procession in London, and they could watch the
+coronation of a youthful queen amid the enthusiasm of a nation. There
+are other stars still further, from which, if the inhabitants had good
+enough telescopes, they would now see a mighty battle in progress not
+far from Brussels. One splendid army could be beheld hurling itself
+time after time against the immovable ranks of the other. They would
+not, indeed, be able to hear the ever-memorable "Up, Guards, and at
+them!" but there can be no doubt that there are stars so far away that
+the rays of light which started from the earth on the day of the
+battle of Waterloo are only just arriving there. Further off still,
+there are stars from which a bird's-eye view could be taken at this
+very moment of the signing of Magna Charta. There are even stars from
+which England, if it could be seen at all, would now appear, not as
+the great England we know, but as a country covered by dense forests,
+and inhabited by painted savages, who waged incessant war with wild
+beasts that roamed through the island. The geological problems that
+now puzzle us would be quickly solved could we only go far enough into
+space and had we only powerful enough telescopes. We should then be
+able to view our earth through the successive epochs of past
+geological time; we should be actually able to see those great animals
+whose fossil remains are treasured in our museums tramping about over
+the earth's surface, splashing across its swamps, or swimming with
+broad flippers through its oceans. Indeed, if we could view our own
+earth reflected from mirrors in the stars, we might still see Moses
+crossing the Red Sea, or Adam and Eve being expelled from Eden.
+
+So important is the subject of star distance that I am tempted to give
+one more illustration in order to bring before you some conception of
+how vast such distances are. I shall take, as before, the nearest of
+the stars so far as known to us, and I hope to be forgiven for taking
+an illustration of a practical and a commercial kind instead of one
+more purely scientific. I shall suppose that a railway is about to be
+made from London to Alpha Centauri. The length of that railway, of
+course, we have already stated: it is twenty billions of miles. So I
+am now going to ask your attention to the simple question as to the
+fare which it would be reasonable to charge for the journey. We shall
+choose a very cheap scale on which to compute the price of a ticket.
+The parliamentary rate here is, I believe, a penny for every mile. We
+will make our interstellar railway fares much less even than this; we
+shall arrange to travel at the rate of one hundred miles for every
+penny. That, surely, is moderate enough. If the charges were so low
+that the journey from London to Edinburgh only cost fourpence, then
+even the most unreasonable passenger would be surely contented. On
+these terms how much do you think the fare from London to this star
+ought to be? I know of one way in which to make our answer
+intelligible. There is a National Debt with which your fathers are,
+unhappily, only too well acquainted; you will know quite enough about
+it yourselves in those days when you have to pay income tax. This debt
+is so vast that the interest upon it is about sixty thousand pounds a
+day, the whole amount of the National Debt being six hundred and
+thirty-eight millions of pounds.
+
+If you went to the booking-office with the whole of this mighty sum in
+your pocket--but stop a moment; could you carry it in your pocket?
+Certainly not, if it were in sovereigns. You would find that after you
+had as many sovereigns as you could conveniently carry there would
+still be some left--so many, indeed, that it would be necessary to get
+a cart to help you on with the rest. When the cart had as great a load
+of sovereigns as the horse could draw there would be still some more,
+and you would have to get another cart; but ten carts, twenty carts,
+fifty carts, would not be enough. You would want five thousand of
+these before you would be able to move off towards the station with
+your money. When you did get there and asked for a ticket at the rate
+of one hundred miles for a penny, do you think you would get any
+change? No doubt some little time would be required to count the
+money, but when it was counted the clerk would tell you that there was
+not enough--that he must have nearly two hundred millions of pounds
+more.
+
+That will give some notion of the distance of the nearest star, and we
+may multiply it by ten, by one hundred, and even by one thousand, and
+still not attain to the distance of some of the more remote stars that
+the telescope shows us.
+
+On account of the immense distances of the stars we can only perceive
+them to be mere points of light. We can never see a star to be a globe
+with marks on it like the moon, or like one of the planets--in fact,
+the better the telescope the smaller does the star seem, though, of
+course, its brightness is increased with every addition to the
+light-grasping power of the instrument.
+
+
+The Brightness and Color of Stars.
+
+Another point to be noticed is the arrangement of stars in classes,
+according to their lustre. The brightest stars, of which there are
+about twenty, are said to be of the first magnitude. Those just
+inferior to the first magnitude are ranked as the second; and those
+just lower than the second are estimated as the third; and so on. The
+smallest points that your unaided eyes will show you are of about the
+sixth magnitude. Then the telescope will reveal stars still fainter
+and fainter, down to what we term the seventeenth or eighteenth
+magnitudes, or even lower still. The number of stars of each magnitude
+increases very much in the classes of small ones.
+
+Most of the stars are white, but many are of a somewhat ruddy hue.
+There are a few telescopic points which are intensely red, some
+exhibit beautiful golden tints, while others are blue or green.
+
+There are some curious stars which regularly change their brilliancy.
+Let me try to illustrate the nature of these variables. Suppose that
+you were looking at a street gas-lamp from a very long distance, so
+that it seemed a little twinkling light; and suppose that some one was
+preparing to turn the gas-cock up and down. Or, better still, imagine
+a little machine which would act regularly so as to keep the light
+first of all at its full brightness for two days and a half, and then
+gradually turn it down until in three or four hours it declines to a
+feeble glimmer. In this low state the light remains for twenty
+minutes; then during three or four hours the gas is to be slowly
+turned on again until it is full. In this condition the light will
+remain for two days and a half, and then the same series of changes is
+to recommence. This would be a very odd form of gas-lamp. There would
+be periods of two days and a half during which it would remain at its
+full; these would be separated by intervals of about seven hours, when
+the gradual turning down and turning up again would be in progress.
+
+The imaginary gas-lamp is exactly paralleled by a star Algol, in the
+constellation of Perseus (Fig. 3), which goes through the series of
+changes I have indicated. Ordinarily speaking, it is a bright star of
+the second magnitude, and, whatever be the cause, the star performs
+its variations with marvellous uniformity. In fact, Algol has always
+arrested the attention of those who observed the heavens, and in early
+times was looked on as the eye of a demon. There are many other stars
+which also change their brilliancy. Most of them require much longer
+periods than Algol, and sometimes a new star which nobody has ever
+seen before will suddenly kindle into brilliancy. It is now known that
+the bright star Algol is attended by a dark companion. This dark star
+sometimes comes between Algol and the observer and cuts off the light.
+Thus it is that the diminution of brightness is produced.
+
+[Illustration: FIG. 3. PERSEUS AND ITS NEIGHBORING STARS INCLUDING
+ALGOL.]
+
+
+Double Stars.
+
+Whenever you have a chance of looking at the heavens through a
+telescope, you should ask to be shown what is called _a double star_.
+There are many stars in the heavens which present no remarkable
+appearance to the unaided eye, but which a good telescope at once
+shows to be of quite a complex nature. These are what we call double
+stars, in which two quite distinct stars are placed so close together
+that the unaided eye is unable to separate them. Under the magnifying
+power of the telescope, however, they are seen to be distinct. In
+order to give some notion of what these objects are like, I shall
+briefly describe three of them. The first lies in that best known
+constellation, the Great Bear. If you look at his tail, which consists
+of three stars, you will see that near the middle one of the three a
+small star is situated; we call this little star Alcor, but it is the
+brighter one near Alcor to which I specially call your attention. The
+sharpest eye would never suspect that it was composed of two stars
+placed close together. Even a small telescope will, however, show this
+to be the case, and this is the easiest and the first observation that
+a young astronomer should make when beginning to turn a telescope to
+the heavens. Of course you will not imagine that I mean Alcor to be
+the second component of the double star; it is the bright star near
+Alcor which is the double. Here are two marbles, and these marbles are
+fastened an inch apart. You can see them, of course, to be separate;
+but if the pair were moved further and further away, then you would
+soon not be able to distinguish between them, though the actual
+distance between the marbles had not altered. Look at these two wax
+tapers which are now lighted; the little flames are an inch apart. You
+would have to view them from a station a third of a mile away if the
+distance between the two flames were to appear the same as that
+between the two components of this double star. Your eye would never
+be able to discriminate between two lights only an inch apart at so
+great a distance; a telescope would, however, enable you to do so, and
+this is the reason why we have to use telescopes to show us double
+stars.
+
+You might look at that double star year after year throughout the
+course of a long life without finding any appreciable change in the
+relative positions of its components. But we know that there is no
+such thing as rest in the universe; even if you could balance a body
+so as to leave it for a moment at rest, it would not stay there, for
+the simple reason that all the bodies round it in every direction are
+pulling at it, and it is certain that the pull in one direction will
+preponderate, so that move it must. Especially is this true in the
+case of two suns like those forming a double star. Placed
+comparatively near each other they could not remain permanently in
+that position; they must gradually draw together and come into
+collision with an awful crash. There is only one way by which such a
+disaster could be averted. That is by making one of these stars
+revolve around the other just as the earth revolves around the sun, or
+the moon revolves around the earth. Some motion must, therefore, be
+going on in every genuine double star, whether we have been able to
+see that motion or not.
+
+Let us now look at another double star of a different kind. This time
+it is in the constellation of Gemini. The heavenly twins are called
+Castor and Pollux. Of these, Castor is a very beautiful double star,
+consisting of two bright points, a great deal closer together than
+were those in the Great Bear; consequently a better telescope is
+required for the purpose of showing them separately. Castor has been
+watched for many years, and it can be seen that one of these stars is
+slowly revolving around the other; but it takes a very long time,
+amounting to hundreds of years, for a complete circuit to be
+accomplished. This seems very astonishing, but when you remember how
+exceedingly far Castor is, you will perceive that that pair of stars
+which appear so close together that it requires a telescope to show
+them apart must indeed be separated by hundreds of millions of miles.
+Let us try to conceive our own system transformed into a double star.
+If we took our outermost planet--Neptune--and enlarged him a good
+deal, and then heated him sufficiently to make him glow like a sun, he
+would still continue to revolve round our sun at the same distance,
+and thus a double star would be produced. An inhabitant of Castor who
+turned his telescope towards us would be able to see the sun as a
+star. He would not, of course, be able to see the earth, but he might
+see Neptune like another small star close to the sun. If generations
+of astronomers in Castor continued their observations of our system,
+they would find a binary star, of which one component took a century
+and a half to go round the other. Need we then be surprised that when
+we look at Castor we observe movements that seem very slow?
+
+There is often so much diffused light about the bright stars seen in a
+telescope, and so much twinkling in some states of the atmosphere,
+that stars appear to dance about in rather a puzzling fashion,
+especially to one who is not accustomed to astronomical observations.
+I remember hearing how a gentleman once came to visit an observatory.
+The astronomer showed him Castor through a powerful telescope as a
+fine specimen of a double star, and then, by way of improving his
+little lesson, the astronomer mentioned that one of these stars was
+revolving around the other. "Oh, yes," said the visitor, "I saw them
+going round and round in the telescope." He would, however, have had
+to wait for a few centuries with his eye to the instrument before he
+would have been entitled to make this assertion.
+
+Double stars also frequently delight us by giving beautifully
+contrasted colors. I dare say you have often noticed the red and the
+green lights that are used on railways in the signal lamps. Imagine
+one of those red and one of those green lights away far up in the sky
+and placed close together, then you would have some idea of the
+appearance that a colored double star presents, though, perhaps, I
+should add that the hues in the heavenly bodies are not so vividly
+different as are those which our railway people find necessary. There
+is a particularly beautiful double star of this kind in the
+constellation of the Swan. You could make an imitation of it by boring
+two holes, with a red-hot needle, in a piece of card, and then
+covering one of these holes with a small bit of the topaz-colored
+gelatine with which Christmas crackers are made. The other star is to
+be similarly colored with blue gelatine. A slide made on this
+principle placed in the lantern gives a very good representation of
+these two stars on the screen. There are many other colored doubles
+besides this one; and, indeed, it is noteworthy that we hardly ever
+find a blue or a green star by itself in the sky; it is always as a
+member of one of these pairs.
+
+
+How We Find What the Stars are Made of.
+
+Here is a piece of stone. If I wanted to know what it was composed of,
+I should ask a chemist to tell me. He would take it into his
+laboratory, and first crush it into powder, and then, with his test
+tubes, and with the liquids which his bottles contain, and his
+weighing scales, and other apparatus, he would tell all about it;
+there is so much of this, and so much of that, and plenty of this, and
+none at all of that. But now, suppose you ask this chemist to tell you
+what the sun is made of, or one of the stars. Of course, you have not
+a sample of it to give him; how, then, can he possibly find out
+anything about it? Well, he can tell you something, and this is the
+wonderful discovery that I want to explain to you. We now put down the
+gas, and I kindle a brilliant red light. Perhaps some of those whom I
+see before me have occasionally ventured on the somewhat dangerous
+practice of making fire-works. If there is any boy here who has ever
+constructed sky-rockets, and put the little balls into the top which
+are to burn with such vivid colors when the explosion takes place, he
+will know that the substance which tinged that fire red must have been
+strontium. He will recognize it by the color; because strontium gives
+a red light which nothing else will give. Here are some of these
+lightning papers, as they are called; they are very pretty and very
+harmless; and these, too, give brilliant red flashes as I throw them.
+The red tint has, no doubt, been produced by strontium also. You see
+we recognized the substance simply by the color of the light it
+produced when burning.
+
+Perhaps some of you have tried to make a ghost at Christmas by
+dressing up in a sheet, and bearing in your hand a ladle blazing with
+a mixture of common salt and spirits of wine, the effect produced
+being a most ghastly one. Some mammas will hardly thank me for this
+suggestion, unless I add that the ghost must walk about cautiously,
+for otherwise the blazing spirit would be very apt to produce
+conflagrations of a kind more extensive than those intended. However,
+by the kindness of Professor Dewar, I am enabled to show the
+phenomenon on a splendid scale, and also free from all danger. I
+kindle a vivid flame of an intensely yellow color, which I think the
+ladies will unanimously agree is not at all becoming to their
+complexions, while the pretty dresses have lost their variety of
+colors. Here is a nice bouquet, and yet you can hardly distinguish the
+green of the leaves from the brilliant colors of the flowers, except
+by trifling differences of shade. Expose to this light a number of
+pieces of variously colored ribbon, pink and red and green and blue,
+and their beauty is gone; and yet we are told that this yellow is a
+perfectly pure color; in fact, the purest color that can be produced.
+I think we have to be thankful that the light which our good sun sends
+us does not possess purity of that description. There is one substance
+which will produce that yellow light; it is a curious metal called
+sodium--a metal so soft that you can cut it with a knife, and so light
+that it will float on water; while, still more strange, it actually
+takes fire the moment it is dropped on the water. It is only in a
+chemical laboratory that you will be likely to meet with the actual
+metallic sodium, yet in other forms the substance is one of the most
+abundant in nature. Indeed, common salt is nothing but sodium closely
+united with a most poisonous gas, a few respirations of which would
+kill you. But this strange metal and this noxious gas, when united,
+become simply the salt for our eggs at breakfast. This pure yellow
+light, wherever it is seen, either in the flame of spirits of wine
+mixed with salt or in that great blaze at which we have been looking,
+is characteristic of sodium. Wherever you see that particular kind of
+light, you know that sodium must have been present in the body from
+which it came.
+
+We have accordingly learned to recognize two substances, namely,
+strontium and sodium, by the different lights which they give out when
+burning. To these two metals we may add a third. Here is a strip of
+white metallic ribbon. It is called magnesium. It seems like a bit of
+tin at the first glance, but indeed it is a very different substance
+from tin; for, look, when I hold it in the spirit-lamp, the strip of
+metal immediately takes fire, and burns with a white light so dazzling
+that it pales the gas-flames to insignificance. There is no other
+substance which will, when kindled, give that particular kind of light
+which we see from magnesium. I can recommend this little experiment as
+quite suitable for trying at home; you can buy a bit of magnesium
+ribbon for a trifle at the opticians; it cannot explode or do any
+harm, nor will you get into any trouble with the authorities provided
+you hold it when burning over a tray or a newspaper, so as to prevent
+the white ashes from falling on the carpet.
+
+There are, in nature, a number of simple bodies called elements.
+Every one of these, when ignited under suitable conditions, emits a
+light which belongs to it alone, and by which it can be distinguished
+from every other substance. I do not say that we can try the
+experiments in the simple way I have here indicated. Many of the
+materials will yield light which will require to be studied by much
+more elaborate artifices than those which have sufficed for us. But
+you will see that the method affords a means of finding out the actual
+substances present in the sun or in the stars. There is a practical
+difficulty in the fact that each of the heavenly bodies contains a
+number of different elements; so that in the light it sends us the
+hues arising from distinct substances are blended into one beam. The
+first thing to be done is to get some way of splitting up a beam of
+light, so as to discover the components of which it is made. You might
+have a skein of silks of different hues tangled together, and this
+would be like the sunbeam as we receive it in its unsorted condition.
+How shall we untangle the light from the sun or a star? I will show
+you by a simple experiment. Here is a beam from the electric light;
+beautifully white and bright, is it not? It looks so pure and simple,
+but yet that beam is composed of all sorts of colors mingled together,
+in such proportions as to form white light. I take a wedge-shaped
+piece of glass called a prism, and when I introduce it into the course
+of the beam, you see the transformation that has taken place (Fig. 4).
+Instead of the white light you have now all the colors of the
+rainbow--red, orange, yellow, green, blue, indigo, violet, marked by
+their initial letters in the figure. These colors are very beautiful,
+but they are transient, for the moment we take away the prism they
+all unite again to form white light. You see what the prism has done;
+it has bent all the light in passing through it; but it is more
+effective in bending the blue than the red, and consequently the blue
+is carried away much further than the red. Such is the way in which we
+study the composition of a heavenly body. We take a beam of its light,
+we pass it through a prism, and immediately it is separated into its
+components; then we compare what we find with the lights given by the
+different elements, and thus we are enabled to discover the substances
+which exist in the distant object whose light we have examined. I do
+not mean to say that the method is a simple one; all I am endeavoring
+to show is a general outline of the way in which we have discovered
+the materials present in the stars. The instrument that is employed
+for this purpose is called the spectroscope. And perhaps you may
+remember that name by these lines, which I have heard from an
+astronomical friend:--
+
+  "Twinkle, twinkle, little star,
+  Now we find out what you are,
+  When unto the midnight sky,
+  We the spectroscope apply."
+
+[Illustration: FIG. 4. HOW A RAY OF LIGHT IS SPLIT UP.]
+
+I am sure it will interest everybody to know that the elements which
+the stars contain are not altogether different from those of which the
+earth is made. It is true there may be substances in the stars of
+which we know nothing here; but it is certain that many of the most
+common elements on the earth are present in the most distant bodies. I
+shall only mention one, the metal iron. That useful substance has been
+found in some of the stars which lie at almost incalculable distances
+from the earth.
+
+
+The Nebulae.
+
+In drawing towards the close of these lectures I must say a few words
+about some dim and mysterious objects to which we have not yet
+alluded. They are what are called nebulae, or little clouds; and in
+one sense they are justly called little, for each of them occupies but
+a very small spot in the sky as compared with that which would be
+filled by an ordinary cloud in our air. The nebulae are, however,
+objects of the most stupendous proportions. Were our earth and
+thousands of millions of bodies quite as big all put together, they
+would not be nearly so great as one of these nebulae. Astronomers
+reckon up the various nebulae by thousands, but I must add that most of
+them are apparently faint and uninteresting. A nebula is sometimes
+liable to be mistaken for a comet. The comet is, as I have already
+explained, at once distinguished by the fact that it is moving and
+changing its appearance from hour to hour, while scores of years
+elapse without changes in the aspect or position of a nebula. The most
+powerful telescopes are employed in observing these faint objects. I
+take this opportunity of showing a picture of an instrument suitable
+for such observations. It is the great reflector of the Paris
+Observatory (Fig. 5).
+
+[Illustration: FIG. 5. A GREAT REFLECTING TELESCOPE.]
+
+[Illustration: FIG. 6. THE RING NEBULA IN LYRA, UNDER DIFFERENT
+TELESCOPIC POWERS.]
+
+There are such multitudes of nebulae that I can only show a few of the
+more remarkable kinds. In Fig. 6 will be seen pictures of a curious
+object in the constellation of Lyra seen under different telescopic
+powers. This is a gigantic ring of luminous gas. To judge of the size
+of this ring let us suppose that a railway were laid across it, and
+the train you entered at one side was not to stop until it reached the
+other side, how long do you think this journey would require? I
+recollect some time ago a picture in _Punch_ which showed a train
+about to start from London to Brighton, and the guard walking up and
+down announcing to the passengers the alarming fact that "this train
+stops nowhere." An old gentleman was seen vainly gesticulating out of
+the window and imploring to be let out ere the frightful journey was
+commenced. In the nebular railway the passengers would almost require
+such a warning.
+
+Let the train start at a speed of a mile a minute, you would think,
+surely, that it must soon cross the ring. But the minutes pass, an
+hour has elapsed; so the distance must be sixty miles at all events.
+The hours creep on into days, the days advance into years, and still
+the train goes on. The years would lengthen out into centuries, and
+even when the train had been rushing on for a thousand years with an
+unabated speed of a mile a minute, the journey would certainly not
+have been completed. Nor do I venture to say what ages must elapse ere
+the terminus at the other side of the ring nebula would be reached.
+
+A cluster of stars viewed in a small telescope will often seem like a
+nebula, for the rays of the stars become blended. A powerful telescope
+will, however, dispel the illusion and reveal the separate stars. It
+was, therefore, thought that all the nebulae might be merely clusters
+so exceedingly remote that our mightiest instruments failed to resolve
+them into stars. But this is now known not to be the case. Many of
+these objects are really masses of glowing gas; such are, for
+instance, the ring nebulae, of which I have just spoken, and the form
+of which I can simulate by a pretty experiment.
+
+We take a large box with a round hole cut in one face, and a canvas
+back at the opposite side. I first fill this box with smoke, and there
+are different ways of doing so. Burning brown paper does not answer
+well, because the supply of smoke is too irregular and the paper
+itself is apt to blaze. A little bit of phosphorus set on fire yields
+copious smoke, but it would be apt to make people cough, and, besides,
+phosphorus is a dangerous thing to handle incautiously, and I do not
+want to suggest anything which might be productive of disaster if the
+experiment was repeated at home. A little wisp of hay, slightly damped
+and lighted, will safely yield a sufficient supply, and you need not
+have an elaborate box like this; any kind of old packing-case, or even
+a bandbox with a duster stretched across its open top and a round hole
+cut in the bottom, will answer capitally. While I have been speaking,
+my assistant has kindly filled this box with smoke, and in order to
+have a sufficient supply, and one which shall be as little
+disagreeable as possible, he has mixed together the fumes of
+hydrochloric acid and ammonia from two retorts shown in Fig. 7. A
+still simpler way of doing the same thing is to put a little common
+salt in a saucer and pour over it a little oil of vitriol; this is put
+into the box, and over the floor of the box common smelling-salts is
+to be scattered. You see there are dense volumes of white smoke
+escaping from every corner of the box. I uncover the opening and give
+a push to the canvas, and you see a beautiful ring flying across the
+room; another ring and another follows. If you were near enough to
+feel the ring, you would experience a little puff of wind; I can show
+this by blowing out a candle which is at the other end of the table.
+These rings are made by the air which goes into a sort of eddy as it
+passes through the hole. All the smoke does is to render the air
+visible. The smoke-ring is indeed quite elastic. If we send a second
+ring hurriedly after the first, we can produce a collision, and you
+see each of the two rings remains unbroken, though both are quivering
+from the effects of the blow. They are beautifully shown along the
+beam of the electric lamp, or, better still, along a sunbeam.
+
+[Illustration: FIG. 7. HOW TO MAKE THE SMOKE RINGS.]
+
+We can make many experiments with smoke-rings. Here, for instance, I
+take an empty box, so far as smoke is concerned, but air-rings can be
+driven forth from it, though you cannot see them, but you can feel
+them even at the other side of the room, and they will, as you see,
+blow out a candle. I can also shoot invisible air-rings at a column of
+smoke, and when the missile strikes the smoke it produces a little
+commotion and emerges on the other side, carrying with it enough of
+the smoke to render itself visible, while the solid black looking ring
+of air is seen in the interior. Still more striking is another way of
+producing these rings, for I charge this box with ammonia, and the
+rings from it you cannot see. There is a column of the vapor of
+hydrochloric acid, that also you cannot see; but when the visible ring
+enters the invisible column, then a sudden union takes place between
+the vapor of the ammonia and the vapor of the hydrochloric acid; the
+result is a solid white substance in extremely fine dust which renders
+the ring instantly visible.
+
+
+What the Nebulae are made of.
+
+There is a fundamental difference between the illumination of these
+little rings that I have shown you and the great rings in the heavens.
+I had to illuminate our smoke with the help of the electric light,
+for, unless I had done so, you would not have been able to see them.
+This white substance formed by the union of ammonia and hydrochloric
+acid has, of course, no more light of its own than a piece of chalk;
+it requires other light falling upon it to make it visible. Were the
+ring nebula in Lyra composed of this material, we could not see it.
+The sunlight which illuminates the planets might, of course, light up
+such an object as the ring, if it wrere comparatively near us; but
+Lyra is at such a stupendous distance that any light which the sun
+could send out there would be just as feeble as the light we receive
+from a fixed star. Should we be able to show our smoke-rings, for
+instance, if, instead of having the electric light, I merely cut a
+hole in the ceiling and allowed the feeble twinkle of a star in the
+Great Bear to shine through? In a similar way the sunbeams would be
+utterly powerless to effect any illumination of objects in these
+stellar distances. If the sun were to be extinguished altogether, the
+calamity would no doubt be a very dire one so far as we are concerned,
+but the effect on the other celestial bodies (moon and planets
+excepted) would be of the slightest possible description. All the
+stars of heaven would continue to shine as before. Not a point in one
+of the constellations wrould be altered, not a variation in the
+brightness, not a change in the hue of any star could be noticed. The
+thousands of nebulae and clusters would be absolutely unaltered; in
+fact, the total extinction of the sun would be hardly remarked in the
+newspapers published in the Pleiades or in Orion. There might possibly
+be a little line somewhere in an odd corner to the effect "Mr.
+So-and-So, our well-known astronomer, has noticed that a tiny star,
+inconspicuous to the eye, and absolutely of no importance whatever,
+has now become invisible."
+
+If, therefore, it be not the sun which lights up this nebula, where
+else can be the source of its illumination? There can be no other star
+in the neighborhood adequate to the purpose, for, of course, such an
+object would be brilliant to us if it were large enough and bright
+enough to impart sufficient illumination to the nebula. It would be
+absurd to say that you could see a man's face by the light of a candle
+while the candle itself was too faint or too distant to be visible.
+The actual facts are, of course, the other way; the candle might be
+visible, when it was impossible to discern the face which it lighted.
+
+Hence we learn that the ring nebula must shine by some light of its
+own, and now we have to consider how it can be possible for such
+material to be self-luminous. The light of a nebula does not seem to
+be like flame; it can, perhaps, be better represented by the pretty
+electrical experiment with Geissler's tubes. These are glass vessels
+of various shapes, and they are all very nearly empty, as you will
+understand when I tell you the way in which they have been prepared. A
+little gas was allowed into each tube, and then almost all the gas was
+taken out again, so that only a mere trace was left. I pass a current
+of electricity through these tubes, and now you see they are glowing
+with beautiful colors. The different gases give out lights of
+different hues, and the optician has exerted his skill so as to make
+the effect as beautiful as possible. The electricity, in passing
+through these tubes, heats the gas which they contain, and makes it
+glow; and just as this gas can, when heated sufficiently, give out
+light, so does the great nebula, which is a mass of gas poised in
+space, become visible in virtue of the heat which it contains.
+
+We are not left quite in doubt as to the constitution of these gaseous
+nebulae, for we can submit their light to the prism in the way I
+explained when we were speaking of the stars. Distant though that ring
+in Lyra may be, it is interesting to learn that the ingredients from
+which it is made are not entirely different from substances we know on
+our earth. The water in this glass, and every drop of water, is formed
+by the union of two gases, of which one is hydrogen. This is an
+extremely light material, as you see by a little balloon which ascends
+so prettily when filled with it. Hydrogen also burns very readily,
+though the flame is almost invisible. When I blow a jet of oxygen
+through the hydrogen, I produce a little flame with a very intense
+heat. For instance, I hold a steel pen in the flame, and it glows and
+sputters, and falls down in white-hot drops. It is needless to say
+that, as a constituent of water, hydrogen is one of the most important
+elements on this earth. It is, therefore, of interest to learn that
+hydrogen in some form or other is a constituent of the most distant
+objects in space that the telescope has revealed.
+
+
+Photographing the Nebulae.
+
+[Illustration: FIG. 8. THE PLEIADES.]
+
+Of late years we have learned a great deal about nebulae, by the help
+which photography has given to us. Look at this group of stars which
+constitutes that beautiful little configuration known as the Pleiades
+(Fig. 8). It looks like a miniature representation of the Great Bear;
+in fact, it would be far more appropriate to call the Pleiades the
+Little Bear than to apply that title to another quite different
+constellation, as has unfortunately been done. The Pleiades form a
+group containing six or seven stars visible to the ordinary eye,
+though persons endowed with exceptionally good vision can usually see
+a few more. In an opera-glass the Pleiades becomes a beautiful
+spectacle, though in a large telescope the stars appear too far apart
+to make a really effective cluster. When Mr. Roberts took a photograph
+of the Pleiades he placed a highly sensitive plate in his telescope,
+and on that plate the Pleiades engraved their picture with their own
+light. He left the plate exposed for hours, and on developing it not
+only were the stars seen, but there were also patches of faint light
+due to the presence of nebulae. It could not be said that the objects
+on the plate were fallacious, for another photograph was taken, when
+the same appearances were reproduced.
+
+When we look at that pretty group of stars which has attracted
+admiration during all time, we are to think that some of those stars
+are merely the bright points in a vast nebula, invisible to our
+unaided eyes or even to our mighty telescopes, though capable of
+recording its trace on the photographic plate. Does not this give us a
+greatly increased notion of the extent of the universe, when we
+reflect that by photography we are enabled to see much which the
+mightiest of telescopes had previously failed to disclose?
+
+Of all the nebulae, numbering some thousands, there is but a single one
+which can be seen without a telescope. It is in the constellation of
+Andromeda, and on a clear dark night can just be seen with the unaided
+eye as a faint stain of light on the sky. It has happened before now
+that persons noticing this nebula for the first time have thought they
+had discovered a comet. I would like you to try and find out this
+object for yourselves.
+
+If you look at it with an opera-glass it appears to be distinctly
+elongated. You can see more of its structure when you view it in
+larger instruments, but its nature was never made clear until some
+beautiful photographs were taken by Mr. Roberts (Fig. 9).
+Unfortunately, the nebula in Andromeda has not been placed in the best
+position for its portrait from our point of view. It seems as if it
+were a rather flat-shaped object, turned nearly edgewise towards us.
+To look at the pattern on a plate, you would naturally hold the plate
+so as to be able to look at it squarely. The pattern would not be seen
+well if the plate were so tilted that its edge was turned towards you.
+That seems to be nearly the way in which we are forced to view the
+nebula in Andromeda. We can trace in the photograph some divisions
+extending entirely round the nebula, showing that it seems to be
+formed of a series of rings; and there are some outlying portions
+which form part of the same system. Truly this is a marvellous object.
+It is impossible for us to form any conception of the true dimensions
+of this gigantic nebula; it is so far off that we have never yet been
+able to determine its distance. Indeed, I may take this opportunity of
+remarking that no astronomer has yet succeeded in ascertaining the
+distance of any nebula. Everything, however, points to the conclusion
+that they are at least as far as the stars.
+
+[Illustration: FIG. 9. THE GREAT NEBULA IN ANDROMEDA.]
+
+It is almost impossible to apply the methods which we use in finding
+the distance of a star to the discovery of the distance of the
+nebulae. These flimsy bodies are usually too ill-defined to admit of
+being measured with the precision and delicacy required for the
+determination of distance. The measurements necessary for this purpose
+can only be made from one star-like point to another similar point. If
+we could choose a star in the nebula and determine its distance, then
+of course, we have the distance of the nebula itself; but the
+difficulty is that we have, in general, no means of knowing whether
+the star does actually lie in the object. It may, for anything we can
+tell, lie billions of miles nearer to us, or billions of miles further
+off, and by merely happening to lie in the line of sight, appear to
+glimmer in the nebula itself.
+
+If we have any assurance that the star is surrounded by a mass of this
+glowing vapor, then it may be possible to measure that nebula's
+distance. It will occasionally happen that grounds can be found for
+believing that a star which appears to be in the glowing gas does
+veritably lie therein, and is not merely seen in the same direction.
+There are hundreds of stars visible in a good drawing or a good
+photograph of the famous object in Andromeda, and doubtless large
+numbers of these are merely stars which happen to lie in the same line
+of sight. The peculiar circumstances attending the history of one star
+seem, however, to warrant us in making the assumption that it was
+certainly in the nebula. The history of this star is a remarkable one.
+It suddenly kindled from invisibility into brilliancy. How is a change
+so rapid in the lustre of a star to be accounted for? In a few days
+its brightness had undergone an extraordinary increase. Of course,
+this does not tell us for certain that the star lay in the glowing
+gas; but the most rational explanation that I have heard offered of
+this occurrence is that due, I believe, to my friend Mr. Monck. He has
+suggested that the sudden outbreak in brilliancy might be accounted
+for on the same principles as those by which we explain the ignition
+of meteors in our atmosphere. If a dark star, moving along with
+terrific speed through space, were suddenly to plunge into a dense
+region of the nebula, heat and light must be evolved in sufficient
+abundance to transform the star into a brilliant object. If,
+therefore, we knew the distance of this star at the time it was in
+Andromeda, we should, of course, learn the distance of that
+interesting object. This has been attempted, and it has thus been
+proved that the Great Nebula must be very much further from us than is
+that star of whose distance I attempted some time ago to give you a
+notion.
+
+We thus realize the enormous size of the Great Nebula. It appears that
+if, on a map of this object, we were to lay down, accurately to scale,
+a map of the solar system, putting the sun in the centre and all the
+planets around their true proportions out to the boundary traced by
+Neptune, this area, vast though it is, would be a mere speck on the
+drawing of the object. Our system would have to be enormously bigger
+before it sufficed to cover anything like the area of the sky included
+in one of these great objects. Here is a sketch of a nebula, Fig. 10,
+and near I have marked a dot, which is to indicate our solar system.
+We may feel confident that the Great Nebula is at the very least as
+mighty as this proportion would indicate.
+
+[Illustration: FIG. 10. THE SOLAR SYSTEM AS COMPARED WITH A GREAT
+NEBULA.]
+
+
+
+
+RAIN AND SNOW
+
+(FROM THE FORMS OF WATER.)
+
+BY JOHN TYNDALL.
+
+
+Oceanic Distillation.
+
+[Illustration: SNOW CRYSTALS.]
+
+At the equator, and within certain limits north and south of it, the
+sun at certain periods of the year is directly overhead at noon. These
+limits are called the Tropics of Cancer and of Capricorn. Upon the
+belt comprised between these two circles the sun's rays fall with
+their mightiest power; for here they shoot directly downwards, and
+heat both earth and sea more than when they strike slantingly.
+
+When the vertical sunbeams strike the land they heat it, and the air
+in contact with the hot soil becomes heated in turn. But when heated
+the air expands, and when it expands it becomes lighter. This lighter
+air rises, like wood plunged into water, through the heavier air
+overhead.
+
+When the sunbeams fall upon the sea the water is warmed, though not so
+much as the land. The warmed water expands, becomes thereby lighter,
+and therefore continues to float upon the top. This upper layer of
+water warms to some extent the air in contact with it, but it also
+sends up a quantity of aqueous vapor, which being far lighter than
+air, helps the latter to rise. Thus both from the land and from the
+sea we have ascending currents established by the action of the sun.
+
+When they reach a certain elevation in the atmosphere, these currents
+divide and flow, part towards the north and part towards the south;
+while from the north and the south a flow of heavier and colder air
+sets in to supply the place of the ascending warm air.
+
+Incessant circulation is thus established in the atmosphere. The
+equatorial air and vapor flow above towards the north and south poles,
+while the polar air flows below towards the equator. The two currents
+of air thus established are called the upper and the lower trade
+winds.
+
+But before the air returns from the poles great changes have occurred.
+For the air as it quitted the equatorial regions was laden with
+aqueous vapor, which could not subsist in the cold polar regions. It
+is there precipitated, falling sometimes as rain, or more commonly as
+snow. The land near the pole is covered with this snow, which gives
+birth to vast glaciers.
+
+It is necessary that you should have a perfectly clear view of this
+process, for great mistakes have been made regarding the manner in
+which glaciers are related to the heat of the sun.
+
+It was supposed that if the sun's heat were diminished, greater
+glaciers than those now existing would be produced. But the lessening
+of the sun's heat would infallibly diminish the quantity of aqueous
+vapor, and thus cut off the glaciers at their source. A brief
+illustration will complete your knowledge here.
+
+In the process of ordinary distillation, the liquid to be distilled is
+heated and converted into vapor in one vessel, and chilled and
+reconverted into liquid in another. What has just been stated renders
+it plain that the earth and its atmosphere constitute a vast
+distilling apparatus in which the equatorial ocean plays the part of
+the boiler, and the chill regions of the poles the part of the
+condenser. In this process of distillation _heat_ plays quite as
+necessary a part as _cold_, and before Bishop Heber could speak of
+"Greenland's icy mountains," the equatorial ocean had to be warmed by
+the sun. We shall have more to say upon this question afterwards.
+
+The heating of the tropical air by the sun is _indirect_. The solar
+beams have scarcely any power to heat the air through which they pass;
+but they heat the land and ocean, and these communicate their heat to
+the air in contact with them. The air and vapor start upwards charged
+with the heat thus communicated.
+
+
+Tropical Rains.
+
+But long before the air and vapor from the equator reach the poles,
+precipitation occurs. Wherever a humid warm wind mixes with a cold dry
+one, rain falls. Indeed the heaviest rains occur at those places where
+the sun is vertically overhead. We must enquire a little more closely
+into their origin.
+
+Fill a bladder about two-thirds full of air at the sea level, and take
+it to the summit of Mount Blanc. As you ascend, the bladder becomes
+more and more distended; at the top of the mountain it is fully
+distended, and has evidently to bear a pressure from within. Returning
+to the sea level you find that the tightness disappears, the bladder
+finally appearing as flaccid as at first.
+
+The reason is plain. At the sea level the air within the bladder has
+to bear the pressure of the whole atmosphere, being thereby squeezed
+into a comparatively small volume. In ascending the mountain, you
+leave more and more of the atmosphere behind; the pressure becomes
+less and less, and by its expansive force the air within the bladder
+swells as the outside pressure is diminished. At the top of the
+mountain the expansion is quite sufficient to render the bladder
+tight, the pressure within being then actually greater than the
+pressure without. By means of an air-pump we can show the expansion of
+a balloon partly filled with air, when the external pressure has been
+in part removed.
+
+But why do I dwell upon this? Simply to make plain to you that the
+_unconfined air_, heated at the earth's surface, and ascending by its
+lightness, must expand more and more the higher it rises in the
+atmosphere.
+
+And now I have to introduce to you a new fact, towards the statement
+of which I have been working for some time. It is this: _The ascending
+air is chilled by its expansion_. Indeed this chilling is one source
+of the coldness of the higher atmospheric regions. And now fix your
+eye upon those mixed currents of air and aqueous vapor which rise from
+the warm tropical ocean. They start with plenty of heat to preserve
+the vapor as vapor; but as they rise they come into regions already
+chilled, and they are still further chilled by their own expansion.
+The consequence might be foreseen. The load of vapor is in great part
+precipitated, dense clouds are formed, their particles coalesce to
+rain-drops, which descend daily in gushes so profuse that the word
+"torrential" is used to express the copiousness of the rainfall. I
+could show you this chilling by expansion, and also the consequent
+precipitation of clouds.
+
+Thus long before the air from the equator reaches the poles its vapor
+is in great part removed from it, having redescended to the earth as
+rain. Still a good quantity of the vapor is carried forward, which
+yields hail, rain, and snow in northern and southern lands.
+
+
+Mountain Condensers.
+
+To complete our view of the process of atmospheric precipitation we
+must take into account the action of mountains. Imagine a south-west
+wind blowing across the Atlantic towards Ireland. In its passage it
+charges itself with aqueous vapor. In the south of Ireland it
+encounters the mountains of Kerry: the highest of these is
+Magillicuddy's Reeks, near Killarney. Now the lowest stratum of this
+Atlantic wind is that which is most fully charged with vapor. When it
+encounters the base of the Kerry Mountains it is tilted up and flows
+bodily over them. Its load of vapor is therefore carried to a height,
+it expands on reaching the height, it is chilled in consequence of
+the expansion, and comes down in copious showers of rain. From this,
+in fact, arises the luxuriant vegetation of Killarney; to this,
+indeed, the lakes owe their water supply. The cold crests of the
+mountains also aid in the work of condensation.
+
+Note the consequence. There is a town called Cahirciveen to the
+south-west of Magillicuddy's Reeks, at which observations of the
+rainfall have been made, and a good distance farther to the
+north-east, right in the course of the south-west wind there is
+another town, called Portarlington, at which observations of rainfall
+have also been made. But before the wind reaches the latter station it
+has passed over the mountains of Kerry and left a great portion of its
+moisture behind it. What is the result? At Cahirciveen, as shown by
+Dr. Lloyd, the rainfall amounts to fifty-nine inches in a year, while
+at Portarlington it is only twenty-one inches.
+
+Again, you may sometimes descend from the Alps when the fall of rain
+and snow is heavy and incessant, into Italy, and find the sky over the
+plains of Lombardy blue and cloudless, the wind at the same time
+_blowing over the plain towards the Alps_. Below the wind is hot
+enough to keep its vapor in a perfectly transparent state; but it
+meets the mountains, is tilted up, expanded, and chilled. The cold of
+the higher summits also helps the chill. The consequence is that the
+vapor is precipitated as rain or snow, thus producing bad weather upon
+the heights, while the plains below, flooded with the same air, enjoy
+the aspect of the unclouded summer sun. Clouds blowing _from_ the
+Alps are also sometimes dissolved over the plains of Lombardy.
+
+In connection with the formation of clouds by mountains, one
+particularly instructive effect may be here noticed. You frequently
+see a streamer of cloud many hundred yards in length drawn out from an
+Alpine peak. Its steadiness appears perfect, though a strong wind may
+be blowing at the same time over the mountain head. Why is the cloud
+not blown away? It _is_ blown away; its permanence is only apparent.
+At one end it is incessantly dissolved; at the other end it is
+incessantly renewed: supply and consumption being thus equalized, the
+cloud appears as changeless as the mountain to which it seems to
+cling. When the red sun of the evening shines upon these
+cloud-streamers they resemble vast torches with their flames blown
+through the air.
+
+Architecture of Snow.
+
+We now resemble persons who have climbed a difficult peak, and thereby
+earned the enjoyment of a wide prospect. Having made ourselves masters
+of the conditions necessary to the production of mountain snow, we are
+able to take a comprehensive and intelligent view of the phenomena of
+glaciers.
+
+[Illustration: SNOW CRYSTALS.]
+
+A few words are still necessary as to the formation of snow. The
+molecules and atoms of all substances, when allowed free play, build
+themselves into definite and, for the most part, beautiful forms
+called crystals. Iron, copper, gold, silver, lead, sulphur, when
+melted and permitted to cool gradually, all show this crystallizing
+power. The metal bismuth shows it in a particularly striking manner,
+and when properly fused and solidified, self-built crystals of great
+size and beauty are formed of this metal.
+
+[Illustration: SNOW-STAR.]
+
+[Illustration: SNOW-STAR.]
+
+If you dissolve salt-petre in water, and allow the solution to
+evaporate slowly, you may obtain large crystals, for no portion of the
+salt is converted into vapor. The water of our atmosphere is fresh
+though it is derived from the salt sea. Sugar dissolved in water, and
+permitted to evaporate, yields crystals of sugar-candy. Alum readily
+crystallizes in the same way. Flints dissolved, as they sometimes are
+in nature, and permitted to crystallize, yield the prisms and pyramids
+of rock crystal. Chalk dissolved and crystallized yields Iceland spar.
+The diamond is crystallized carbon. All our precious stones, the
+ruby, sapphire, beryl, topaz, emerald, are all examples of this
+crystallizing power.
+
+[Illustration: SNOW-STAR.]
+
+You have heard of the force of gravitation, and you know that it
+consists of an attraction of every particle of matter for every other
+particle. You know that planets and moons are held in their orbits by
+this attraction. But gravitation is a very simple affair compared to
+the force, or rather forces, of crystallization. For here the ultimate
+particles of matter, inconceivably small as they are, show themselves
+possessed of attractive and repellent poles, by the mutual action of
+which the shape and structure of the crystal are determined. In the
+solid condition the attracting poles are rigidly locked together; but
+if sufficient heat be applied the bond of union is dissolved, and in
+the state of fusion the poles are pushed so far asunder as to be
+practically out of each other's range. The natural tendency of the
+molecules to build themselves together is thus neutralized.
+
+This is the case with water, which as a liquid is to all appearance
+formless. When sufficiently cooled the molecules are brought within
+the play of the crystallizing force, and they then arrange themselves
+in forms of indescribable beauty. When snow is produced in calm air,
+the icy particles build themselves into beautiful stellar shapes, each
+star possessing six rays. There is no deviation from this type, though
+in other respects the appearances of the snow-stars are infinitely
+various. In the polar regions these exquisite forms were observed by
+Dr. Scoresby, who gave numerous drawings of them. I have observed them
+in mid-winter filling the air, and loading the slopes of the Alps. But
+in England they are also to be seen, and no words of mine could convey
+so vivid an impression of their beauty as the annexed drawings of a
+few of them, executed at Greenwich by Mr. Glaisher.
+
+[Illustration: SNOW-STAR.]
+
+It is worth pausing to think what wonderful work is going on in the
+atmosphere during the formation and descent of every snow-shower; what
+building power is brought into play! and how imperfect seem the
+productions of human minds and hands when compared with those formed
+by the blind forces of nature!
+
+But who ventures to call the forces of nature blind? In reality, when
+we speak thus we are describing our own condition. The blindness is
+ours; and what we really ought to say, and to confess, is that our
+powers are absolutely unable to comprehend either the origin or the
+end of the operations of nature.
+
+But while we thus acknowledge our limits, there is also reason for
+wonder at the extent to which science has mastered the system of
+nature. From age to age, and from generation to generation, fact has
+been added to fact, and law to law, the true method and order of the
+Universe being thereby more and more revealed. In doing this science
+has encountered and overthrown various forms of superstition and
+deceit, of credulity and imposture. But the world continually produces
+weak persons and wicked persons; and as long as they continue to exist
+side by side, as they do in this our day, very debasing beliefs will
+also continue to infest the world.
+
+
+Atomic Poles.
+
+"What did I mean when, a few moments ago I spoke of attracting and
+repellent poles?" Let me try to answer this question. You know that
+astronomers and geographers speak of the earth's poles, and you have
+also heard of magnetic poles, the poles of a magnet being the points
+at which the attraction and repulsion of the magnet are as it were
+concentrated.
+
+Every magnet possesses two such poles; and if iron filings be
+scattered over a magnet, each particle becomes also endowed with two
+poles. Suppose such particles devoid of weight and floating in our
+atmosphere, what must occur when they come near each other? Manifestly
+the repellent poles will retreat from each other, while the attractive
+poles will approach and finally lock themselves together. And
+supposing the particles, instead of a single pair, to possess several
+pairs of poles arranged at definite points over their surfaces; you
+can then picture them, in obedience to their mutual attractions and
+repulsions, building themselves together to form masses of definite
+shape and structure.
+
+Imagine the molecules of water in calm cold air to be gifted with
+poles of this description, which compel the particles to lay
+themselves together in a definite order, and you have before your
+mind's eye the unseen architecture which finally produces the visible
+and beautiful crystals of the snow. Thus our first notions and
+conceptions of poles are obtained from the sight of our eyes in
+looking at the effects of magnetism; and we then transfer these
+notions and conceptions to particles which no eye has ever seen. The
+power by which we thus picture to ourselves effects beyond the range
+of the senses is what philosophers call the Imagination, and in the
+effort of the mind to seize upon the unseen architecture of crystals,
+we have an example of the "scientific use" of this faculty. Without
+imagination we might have _critical_ power, but not _creative_ power
+in science.
+
+
+Architecture of Lake Ice.
+
+We have thus made ourselves acquainted with the beautiful snow-flowers
+self-constructed by the molecules of water in calm, cold air. Do the
+molecules show this architectural power when ordinary water is frozen?
+What, for example, is the structure of the ice over which we skate in
+winter? Quite as wonderful as the flowers of the snow. The observation
+is rare, if not new, but I have seen in water slowly freezing
+six-rayed ice-stars formed, and floating free on the surface. A
+six-rayed star, moreover, is typical of the construction of all our
+lake ice. It is built up of such forms wonderfully interlaced.
+
+Take a slab of lake ice and place it in the path of a concentrated
+sunbeam. Watch the track of the beam through the ice. Part of the beam
+is stopped, part of it goes through; the former produces internal
+liquefaction, the latter has no effect whatever upon the ice. But the
+liquefaction is not uniformly diffused. From separate spots of the ice
+little shining points are seen to sparkle forth. Every one of those
+points is surrounded by a beautiful liquid flower with six petals.
+
+Ice and water are so optically alike that unless the light fall
+properly upon these flowers you cannot see them. But what is the
+central spot? A vacuum. Ice swims on water because, bulk for bulk, it
+is lighter than water; so that when ice is melted it shrinks in size.
+Can the liquid flowers then occupy the whole space of the ice melted?
+Plainly no. A little empty space is formed with the flowers, and this
+space, or rather its surface, shines in the sun with the lustre of
+burnished silver.
+
+In all cases the flowers are formed parallel to the surface of
+freezing. They are formed when the sun shines upon the ice of every
+lake; sometimes in myriads, and so small as to require a magnifying
+glass to see them. They are always attainable, but their beauty is
+often marred by internal defects of the ice. Every one portion of the
+same piece of ice may show them exquisitely, while a second portion
+shows them imperfectly.
+
+Annexed is a very imperfect sketch of these beautiful figures.
+
+Here we have a reversal of the process of crystallization. The
+searching solar beam is delicate enough to take the molecules down
+without deranging the order of their architecture. Try the experiment
+for yourself with a pocket-lens on a sunny day. You will not find the
+flowers confused; they all lie parallel to the surface of freezing. In
+this exquisite way every bit of the ice over which our skaters glide
+in winter is put together.
+
+I said that a portion of the sunbeam was stopped by the ice and
+liquefied it. What is this portion? The dark heat of the sun. The
+great body of the light waves and even a portion of the dark ones,
+pass through the ice without losing any of their heating power. When
+properly concentrated on combustible bodies, even after having passed
+through the ice, their burning power becomes manifest.
+
+[Illustration: LIQUID FLOWERS IN LAKE ICE.]
+
+And the ice itself may be employed to concentrate them. With an
+ice-lens in the polar regions Dr. Scoresby has often concentrated the
+sun's rays so as to make them burn wood, fire gunpowder, and melt
+lead; thus proving that the heating power is retained by the rays,
+even after they have passed through so cold a substance.
+
+By rendering the rays of the electric lamp parallel, and then sending
+them through a lens of ice, we obtain all the effects which Dr.
+Scoresby obtained with the rays of the sun.
+
+[Illustration]
+
+
+
+
+THE ORGANIC WORLD
+
+(FROM THE ELEMENTS OF SCIENCE.)
+
+BY ST. GEORGE MIVART F.R.S.
+
+
+The number of all the various kinds of living creatures is so enormous
+that it would be impossible to study them profitably, were they not
+classified in an orderly manner. Therefore the whole mass has been
+divided, in the first place, into two supreme groups, fancifully
+termed kingdoms--the "animal kingdom" and the "vegetal kingdom." Each
+of these is subdivided into an orderly series of subordinate groups,
+successively contained one a within the other, and named sub-kingdoms,
+classes, orders, families, genera and species. The lowest group but
+one is the "genus," which contains one or more different kinds termed
+"species," as e.g., the species "wood anemone" and the species "blue
+titmouse." The lowest group of all--a species--may be said to consist
+of individuals which differ from each other only by trifling
+characters, such as characters due to difference of sex, while their
+peculiar organization is faithfully reproduced by generation as a
+whole, though small individual differences exist in all cases.
+
+The vegetal, or vegetable, kingdom, consists of the great mass of
+flowering plants, many of which, however, have such inconspicuous
+flowers that they are mistakenly regarded as flowerless, as is often
+the case with the grasses, the pines, and the yews. Another mass, or
+sub-kingdom, of plants consists of the really flowerless plants, such
+as the ferns, horsetails (Fig. 1), lycopods, and mosses. Sea and
+fresh-water weeds (_algae_), and mushrooms, or "moulds," of all kinds
+(_fungi_), amongst which are the now famous "bacteria," constitute a
+third and lowest set of plants.
+
+[Illustration: FIG. 1. HORSE-TAIL (_Equisetum drummondii_).]
+
+The animal kingdom consists, first, of a sub-kingdom of animals which
+possess a spinal column, or backbone, and which are known as
+vertebrate animals. Such are all beasts, birds, reptiles, and fishes.
+There are also a variety of remotely allied marine organisms known as
+tunicates, sea-squirts, or ascidians (Fig. 2). There is, further, an
+immense group of arthropods, consisting of all insects, crab-like
+creatures, hundred-legs and their allies, with spiders, scorpions,
+tics and mites. We have also the sub-kingdom of shell-fish or
+molluscs, including cuttle-fishes, snails, whelks, limpets, the
+oyster, and a multitude of allied forms. A multitudinous sub-kingdom of
+worms also exists, as well as another of star-fishes and their
+congeners. There is yet another of zoophytes, or polyps, and another
+of sponges, and, finally, we have a sub-kingdom of minute creatures,
+or animalculae, of very varied forms, which may make up the sub-kingdom
+of _Protozoa_, consisting of animals which are mostly unicellular.
+
+[Illustration: FIG. 2. A TUNICATE (_Ascidia_).]
+
+Multitudinous and varied as are the creatures which compose this
+immense organic world, they nevertheless exhibit a very remarkable
+uniformity of composition in their essential structure. Every living
+creature from a man to a mushroom, or even to the smallest animalcule
+or unicellular plant is always partly fluid, but never entirely so.
+Every living creature also consists in part (and that part is the most
+active living part) of a soft, viscid, transparent, colorless
+substance, termed protoplasm, which can be resolved into the four
+elements, oxygen, hydrogen, nitrogen and carbon. Besides these four
+elements, living organisms commonly contain sulphur, phosphorus,
+chlorine, potassium, sodium, calcium, magnesium and iron.
+
+In the fact that living creatures always consist of the four elements,
+oxygen, hydrogen, nitrogen and carbon, we have a fundamental character
+whereby the organic and inorganic (or non-living) worlds are to be
+distinguished, for as we have seen, inorganic bodies, instead of being
+thus uniformly constituted, may consist of the most diverse elements
+and sometimes of but two or even of only one.
+
+Again, many minerals, such as crystals, are bounded by plain surfaces,
+and, with very few exceptions (spathic and hematite iron and dolomite
+are such exceptions) none are bounded by curved lines and surfaces,
+while living organisms are bounded by such lines and surfaces.
+
+Yet, again, if a crystal be cut through, its internal structure will
+be seen to be similar throughout. But if the body of any living
+creature be divided, it will, at the very least, be seen to consist of
+a variety of minute distinct particles, called "granules," variously
+distributed throughout its interior.
+
+All organisms consist either--as do the simplest, mostly microscopic,
+plants and animals--of a single minute mass of protoplasm, or of a
+few, or of many, or of an enormous aggregation of such before-mentioned
+particles, each of which is one of those bodies named a "cell" (Fig.
+3). Cells may, or may not, be enclosed in an investing coat or
+"cell-wall." Every cell generally contains within it a denser,
+normally spheroidal, body known as the nucleus.
+
+Now protoplasm is a very unstable substance--as we have seen many
+substances are whereof nitrogen is a component part--and it possesses
+active properties which are not present in the non-living, or
+inorganic world. In the latter, differences of temperature will
+produce motion in the shape of "currents," as we have seen with
+respect to masses of air and water. But in a portion of protoplasm,
+an internal circulation of currents in definite lines will establish
+itself from other causes.
+
+Inorganic bodies, as we have seen, will expand with heat, as they may
+also do from imbibing moisture; but living protoplasm has an
+apparently spontaneous power of contraction and expansion under
+certain external conditions which do not occasion such movements in
+inorganic matter.
+
+[Illustration: FIG. 3. CELL FROM A SALAMANDER. _n_, nucleus; _n'_,
+nucleolus embedded in the network of chromatin threads; _k_, network
+of the cell external to the nucleus; _a_, attraction-sphere or
+archoplasm containing minute bodies called centrosomes; _cl_, membrane
+enclosing the cell externally, _nl_, membrane surrounding the nucleus;
+_c_, centrosomes.]
+
+Under favoring conditions, protoplasm has a power of performing
+chemical changes, which result in producing heat far more gently and
+continuously than it is produced by the combustion of inorganic
+bodies. Thus it is that the heat is produced which makes its presence
+evident to us in what we call "warm-blooded animals," the most
+warm-blooded of all being birds.
+
+Protoplasm has also the wonderful power of transforming certain
+adjacent substances into material like itself--into its own
+substance--and so, in a sense, creating a new material. Thus it is
+that organisms have the power to nourish themselves and grow. An
+animal would vainly swallow the most nourishing food if the ultimate,
+protoplasmic particles of its body had not this power of
+"transforming" suitable substances brought near them in ways to be
+hereinafter noticed.
+
+Without that, no organism could ever "grow." The growth of organisms
+is utterly different from the increase in size of inorganic bodies.
+Crystals, as we have seen, grow merely by external increment; but
+organisms grow by an increment which takes place in the very innermost
+substance of the tissues which compose their bodies, and the innermost
+substance of the cells which compose such tissues; this peculiar form
+of growth is termed _intussusception_.
+
+Protoplasm, after thus augmenting its mass, has a further power of
+spontaneous division, whereby the mass of the entire organism whereof
+such protoplasm forms a part, is augmented and so growth is brought
+about.
+
+The small particles of protoplasm which constitute "cells" are far
+indeed from being structureless. Besides the nucleus already mentioned
+there is a delicate network of threads of a substance called
+_chromatin_ within it, and another network permeating the fluid of the
+cell substance, which invest the nucleus often with further
+complications. These networks generally perform (or undergo) a most
+complex series of changes every time a cell spontaneously divides. In
+certain cases, however, it appears that the nucleus divides into two
+in a more simple fashion, the rest of the cell contents subsequently
+dividing--each half enclosing one part of the previously divided
+nucleus. It is by a continued process of cell division that the
+complex structures of the most complex organisms is brought about.
+
+The division of a cell, or particle of protoplasm, is indeed a
+necessary consequence of its complete nutrition.
+
+For new material can only be absorbed by its surface. But as the cell
+grows, the proportion borne by its surface to its mass, continually
+decreases; therefore this surface must soon be too small to take in
+nourishment enough, and the particle, or cell, must therefore either
+die or divide. By dividing, its parts can continue the nutritive
+process till their surface, in turn, becomes insufficient, when they
+must divide again, and so on. Thus the term "feeding" has two senses.
+"To feed a horse," ordinarily means to give it a certain quantity of
+hay, oats or what not; and such indeed is one kind of feeding. But
+obviously, if the nourishment so taken could not get from the stomach
+and intestines into the ultimate particles and cells of the horse's
+body, the horse could not be nourished, and still less could it grow.
+It is this latter process, called assimilation, which is the real and
+essential process of feeding, to which the process ordinarily so
+called is but introductory.
+
+Protoplasm has also the power of forming and ejecting from its own
+substance, other substances which it has made, but which are of a
+different nature to its own. This function, as before said, is termed
+secretion; and we know the liver secretes bile, and that the cow's
+udder secretes milk.
+
+Here again we have an external and an internal process. The milk is
+drawn forth from a receptacle, the udder, into which it finds its way,
+and so, in a superficial sense, it may be called an organ of
+secretion. Nevertheless the true internal secretion takes place in
+the innermost substance of the cells or particles of protoplasm, of
+the milk-land, which particles really form that liquid.
+
+But every living creature consists at first entirely of a particle of
+protoplasm. Therefore every other kind of substance which may be found
+in every kind of plant or animal, must have been formed through it,
+and be, in fact, a secretion from protoplasm. Such is the rosy cheek
+of an apple, or of a maiden, the luscious juice of the peach, the
+produce of the castor-oil plant, the baleen that lines the whale's
+enormous jaws, as well as that softest product, the fur of the
+chinchilla. Indeed, every particle of protoplasm requires, in order
+that it may live, a continuous process of exchange. It needs to be
+continuously first built up by food, and then broken down by
+discharging what is no longer needful for its healthy existence. Thus
+the life of every organism is a life of almost incessant change, not
+only in its being as a whole, but in that of all its protoplasmic
+particles also.
+
+[Illustration: FIG. 4. AMOEBA SHOWN IN TWO OF THE MANY IRREGULAR
+SHAPES IT ASSUMES. _(After Howes_.)
+
+The clear space within it is a contractile vesicle. The dark body is
+the nucleus. In the right-hand figure there is shown a particle of
+food, passing through the external surface.]
+
+
+Prominent among such processes is that of an interchange of gases
+between the living being and its environment. This process consists in
+an absorption of oxygen and a giving-out of carbonic acid, which
+exchange is termed respiration.
+
+Lastly, protoplasm has a power of motion when appropriately acted on.
+It will then contract or expand its shape by alternate protrusions and
+retractions of parts of its substance. These movements are termed
+amoebiform, because they quite resemble the movements of a small
+animalcule which is named amoeba. (See Fig. 4.)
+
+Such is the ultimate structure, and such are the fundamental
+activities or functions of living organisms, as far as they can here
+be described, from the lowest animalcule and unicellular plant, up to
+the most complex organisms and the body of man himself.
+
+[Illustration]
+
+
+
+
+INHABITANTS OF MY POOL
+
+(FROM MAGIC GLASSES.)
+
+BY ARABELLA B. BUCKLEY.
+
+
+The pool lies in a deep hollow among a group of rocks and boulders,
+close to the entrance of the cove, which can only be entered at low
+water; it does not measure more than two feet across, so that you can
+step over it, if you take care not to slip on the masses of green and
+brown seaweed growing over the rocks on its sides, as I have done many
+a time when collecting specimens for our salt-water aquarium. I find
+now the only way is to lie flat down on the rock, so that my hands and
+eyes are free to observe and handle, and then, bringing my eye down to
+the edge of the pool, to lift the seaweeds and let the sunlight enter
+into the chinks and crannies. In this way I can catch sight of many a
+small being either on the seaweed or the rocky ledges, and even
+creatures transparent as glass become visible by the thin outline
+gleaming in the sunlight. Then I pluck a piece of seaweed, or chip off
+a fragment of rock with a sharp-edged collecting knife, bringing away
+the specimen uninjured upon it, and place it carefully in its own
+separate bottle to be carried home alive and well.
+
+Now though this little pool and I are old friends, I find new
+treasures in it almost every time I go, for it is almost as full of
+living things as the heavens are of stars, and the tide as it comes
+and goes brings many a mother there to find a safe home for her little
+ones, and many a waif and stray to seek shelter from the troublous
+life of the open ocean.
+
+You will perhaps find it difficult to believe that in this rock-bound
+basin there can be millions of living creatures hidden away among the
+fine feathery weeds; yet so it is. Not that they are always the same.
+At one time it may be the home of myriads of infant crabs, not an
+eighth of an inch long, another of baby sea-urchins only visible to
+the naked eye as minute spots in the water, at another of young
+jelly-fish growing on their tiny stalks, and splitting off one by one
+as transparent bells to float away with the rising tide. Or it may be
+that the whelk has chosen this quiet nook to deposit her leathery
+eggs; or young barnacles, periwinkles, and limpets are growing up
+among the green and brown tangles, while the far-sailing velella and
+the stay-at-home sea-squirts, together with a variety of other
+sea-animals, find a nursery and shelter in their youth in this quiet
+harbor of rest.
+
+And besides these casual visitors there are numberless creatures which
+have lived and multiplied there, ever since I first visited the pool.
+Tender red, olive-colored, and green seaweeds, stony corallines, and
+acorn-barnacles lining the floor, sea-anemones clinging to the sides,
+sponges tiny and many-colored hiding under the ledges, and limpets and
+mussels wedged in the cracks. These can be easily seen with the naked
+eye, but they are not the most numerous inhabitants; for these we
+must search with a magnifying glass, which will reveal to us wonderful
+fairy-forms, delicate crystal vases with tiny creatures in them whose
+transparent lashes make whirlpools in the water, living crystal bells
+so tiny that whole branches of them look only like a fringe of hair,
+jelly globes rising and falling in the water, patches of living jelly
+clinging to the rocky sides of the pool, and a hundred other forms,
+some so minute that you must examine the fine sand in which they lie
+under a powerful microscope before you can even guess that they are
+there.
+
+[Illustration: FIG. 1. GROUP OF SEAWEEDS.
+
+(Natural size.)
+
+1, _Ulva Linza._ 2, _Sphacelaria filicina._ 3, _Polysiphonia
+urceolata._ 4, _Corallina officinalis._]
+
+So it has proved a rich hunting-ground, where summer and winter,
+spring and autumn, I find some form to put under my magic glass. There
+I can watch it for weeks growing and multiplying under my care; moved
+only from the aquarium, where I keep it supplied with healthy
+sea-water, to the tiny transparent trough in which I place it for a
+few hours to see the changes it has undergone. I could tell you
+endless tales of transformations in these tiny lives, but I want
+to-day to show you a few of my friends, most of which I brought
+yesterday fresh from the pool, and have prepared for you to examine.
+
+[Illustration: FIG. 2. _Ulva lactuca_, A GREEN-SEAWEED, GREATLY
+MAGNIFIED TO SHOW STRUCTURE. (_After Orested)._
+
+s, Spores in the cells, _ss_, Spores swimming out. _h_, Holes through
+which spores have escaped.]
+
+Let us begin with seaweeds. I have said that there are three leading
+colors in my pool--green, olive, and red--and these tints mark roughly
+three kinds of weed, though they occur in an endless variety of
+shapes. Here is a piece of the beautiful pale green seaweed, called
+the Laver or Sea-Lettuce, _Ulva Linza_ (1, Fig. 1),[1] which grows in
+long ribbons in a sunny nook in the water. I have placed under the
+first microscope a piece of this weed which is just sending out young
+seaweeds in the shape of tiny cells, with lashes very like those we
+saw coming from the moss-flower, and I have pressed them in the
+position in which they would naturally leave the plant. You will also
+see on this side several cells in which these tiny spores are forming,
+ready to burst out and swim; for this green weed is merely a
+collection of cells, like the single-celled plants on land. Each cell
+can work as a separate plant; it feeds, grows, and can send out its
+own young spores.
+
+[Footnote 1: The slice given in Fig. 2 is from a broader-leaved form,
+_U. lactuca_, because this species, being composed of only one layer
+of cells, is better seen. _Ulva Linza_ is composed of two layers of
+cells.]
+
+This deep olive-green feathery weed (2, Fig. 1), of which a piece is
+magnified under the next microscope (2, Fig. 3), is very different. It
+is a higher plant, and works harder for its living, using the darker
+rays of sunlight which penetrate into shady parts of the pool. So it
+comes to pass that its cells divide the work. Those of the feathery
+threads make the food, while others, growing on short stalks on the
+shafts of the feather, make and send out the young spores.
+
+Lastly, the lovely red threadlike weeds, such as this _Polysiphonia
+urceolata_ (3, Fig. 1), carry actual urns on their stems like those of
+mosses. In fact, the history of these urns (see 3, Fig. 3), is much
+the same in the two classes of plants, only that instead of the urn
+being pushed up on a thin stalk as in the moss, it remains on the
+seaweed close down to the stem, when it grows out of the plant-egg,
+and the tiny plant is shut in till the spores are ready to swim out.
+
+[Illustration: FIG. 3. THREE SEAWEEDS OF FIG. 1 MUCH MAGNIFIED TO SHOW
+FRUITS. (_Harvey._)
+
+2, _Sphacelaria filicina._ 3, _Polysiphonia urceolata._ 4, _Corallina
+officinalis._]
+
+The stony corallines (4, Figs. 1 and 3), which build so much carbonate
+of lime into their stems, are near relations of the red seaweeds.
+There are plenty of them in my pool. Some of them, of a deep purple
+color, grow upright in stiff groups about three or four inches high;
+and others, which form crusts over the stones and weeds, are a pale
+rose color; but both kinds, when the plant dies, leaving the stony
+skeleton (1, Fig. 4), are a pure white, and used to be mistaken for
+corals. They belong to the same order of plants as the red weeds,
+which all live in shady nooks in the pools, and are the highest of
+their race.
+
+[Illustration: FIG. 4. CORALLINE AND SERTULARIA, TO SHOW LIKENESS
+BETWEEN THE ANIMAL SERTULARIA AND THE PLANT CORALLINE.
+
+1, _Corallina officinalis._ 2, _Sertularia filicula._]
+
+My pool is full of different forms of these four weeds. The green
+ribbons float on the surface rooted to the sides of the pool, and, as
+the sun shines upon it, the glittering bubbles rising from them show
+that they are working up food out of the air in the water, and giving
+off oxygen. The brown weeds lie chiefly under the shelves of rocks,
+for they can manage with less sunlight, and use the darker rays which
+pass by the green weeds; and last of all, the red weeds and
+corallines, small and delicate in form, line the bottom of the pool in
+its darkest nooks.
+
+And now if I hand round two specimens,--one a coralline, and the other
+something you do not yet know,--I am sure you will say at first sight
+that they belong to the same family, and, in fact, if you buy at the
+seaside a group of seaweeds gummed on paper, you will most likely get
+both these among them. Yet the truth is; that while the coralline (1,
+Fig. 4) is a plant, the other specimen (2), which is called
+_Sertularia filicula_, is an animal.
+
+This special sertularian grows up right in my pool on stones or often
+on seaweeds, but I have here (Fig. 5) another and much smaller one
+which lives literally in millions hanging its cups downwards. I find
+it not only under the narrow ledges of the pool sheltered by the
+seaweed, but forming a fringe along all the rocks on each side of the
+cove near to low-water mark, and for a long time I passed it by
+thinking it was of no interest. But I have long since given up
+thinking this of anything, especially in my pool, for my magic glass
+has taught me that there is not even a living speck which does not
+open out into something marvellous and beautiful. So I chipped off a
+small piece of rock and brought the fringe home, and found, when I
+hung it up in clear sea-water as I have done over this glass trough
+(Fig. 5) and looked at it through the lens, that each thread of the
+dense fringe, in itself not a quarter of an inch deep, turns out to be
+a tiny sertularian with at least twenty mouths. You can see this with
+your pocket lens even as it hangs here, and when you have examined it
+you can by and by take off one thread and put it carefully in the
+trough. I promise you a sight of the most beautiful little beings
+which exist in nature.
+
+[Illustration: FIG. 5. _Sertularia tenella_, HANGING FROM A SPLINT OF
+ROCK OVER A WATER TROUGH. ALSO PIECE ENLARGED TO SHOW THE ANIMAL
+PROTRUDING.]
+
+Come and look at it. It is a horny-branched stem with a double row of
+tiny cups all along each side. Out of these cups there appear a row of
+tiny cups all along each side (see Fig. 5), Out of these cups there
+appear from time to time sixteen minute transparent tentacles as fine
+as spun glass, which wave about in the water. If you shake the glass a
+little, in an instant each crystal star vanishes into its cup, to come
+out again a few minutes later; so that now here, now there, the
+delicate animal-flowers spread out on each side of the stem, and the
+tree is covered with moving beings. These tentacles are feelers, which
+lash food into a mouth and stomach in each cup, where it is digested
+and passed, through a hole in the bottom, along a jelly thread which
+runs down the stem and joins all the mouths together. In this way the
+food is distributed all over the tree, which is, in fact, one animal
+with many feeding-cups. Some day I will show you one of these cups
+with the tentacles stretched out and mounted on a slide, so that you
+can examine a tentacle with a very strong magnifying power. You will
+then see that it is dotted over with cells, in which are coiled fine
+threads. The animal uses these threads to paralyze the creatures on
+which it feeds, for at the base of each thread there is a poison
+gland.
+
+In the larger Sertularia the whole branched tree is connected by jelly
+threads, running through the stem, and all the thousands of mouths are
+spread out in the water. One large form called _Sertularia cupressina_
+grows sometimes three feet high and bears as many as a hundred
+thousand cups, with living mouths, on its branches.
+
+The next of my minute friends I can only show to the class in a
+diagram, but you will see it under the fourth microscope by and by. I
+had great trouble in finding it yesterday, though I know its haunts
+upon the green weed, for it is so minute and transparent that even
+when the weed is in a trough a magnifying-glass will scarcely detect
+it. And I must warn you that if you want to know any of the minute
+creatures we are studying, you must visit one place constantly. You
+may in a casual way find many of them on seaweed, or in the damp ooze
+and mud, but it will be by chance only; to look for them with any
+certainty you must take trouble in making their acquaintance.
+
+[Illustration: FIG. 6. _Thuricolla folliculata_ and _Chilomonas
+amygdalum_. (_Saville Kent_.)
+
+1, _Thuricolla_ erect. 2, Retracted. 3, Dividing. 4, _Chilomonas
+amygdalum. hc,_ Horny carapace, _cv_, Contractile vesicle. _v_ Closing
+valves.]
+
+Turning then to the diagram (Fig. 6) I will describe it as I hope you
+will see it under the microscope--a curious, tiny, perfectly
+transparent open-mouthed vase standing upright on the weed, and having
+an equally transparent being rising up in it and waving its tiny
+lashes in the water. This is really all one animal, the vase _hc_
+being the horny covering or carapace of the body, which last stands up
+like a tube in the centre. If you watch carefully, you may even see
+the minute atoms of food twisting round inside the tube until they are
+digested, after they have been swept in at the wide open mouth by the
+whirling lashes. You will see this more clearly if you put a little
+rice-flour, very minutely powdered and colored by carmine, into the
+water; for you can trace these red atoms into some round spaces called
+_vacuoles_ which are dotted over the body of the animal, and are
+really globules of watery fluid in which the food is probably partly
+digested.
+
+You will notice, however, one round clear space _(cv)_ into which they
+do not go, and after a time you will be able to observe that this
+round spot closes up or contracts very quickly, and then expands again
+very slowly. As it expands it fills with a clear fluid, and
+naturalists have not yet decided exactly what work it does. It may
+serve the animal either for breathing, or as a very simple heart,
+making the fluids circulate in the tube. The next interesting point
+about this little being is the way it retreats into its sheltering
+vase. Even while you are watching, it is quite likely it may all at
+once draw itself down to the bottom as in No. 2, and folding down the
+valves _w_ of horny teeth which grow on each side, shut itself in from
+some fancied danger. Another very curious point is that, besides
+sending forth young ones, these creatures multiply by dividing in two
+(see No. 3, Fig. 6), each one closing its own part of the vase into a
+new home.
+
+There are hundreds of these Infusoria, as they are called, in my pond,
+some with vases, some without, some fixed to weeds and stones, others
+swimming about freely. Even in the water-trough in which this
+Thuricolla stands, I saw several smaller forms, and the next
+microscope has a trough filled with the minutest form of all, called a
+Monad. These are so small that two thousand of them could lie side by
+side in an inch; that is, if you could make them lie at all, for they
+are the most restless little beings, darting hither and thither,
+scarcely even halting except to turn back. And yet though there are so
+many of them, and as far as we know they have no organs of sight, they
+never run up against each other, but glide past more cleverly than any
+clear-sighted fish. These creatures are mostly to be found among
+decaying seaweed, and though they are so tiny, you can still see
+distinctly the clear space contracting and expanding within them.
+
+[Illustration: FIG. 7. LIVING DIATOMS.
+
+_a, Cocconema lanceolatum. b, Bacillaria paradoxa. c, Gomphonema
+marinum. d, Diatoma hyalina_.]
+
+But if there are so many thousands of mouths to feed, on the tree-like
+Sertulariae as well as in all these Infusoria, where does the food come
+from? Partly from the numerous atoms of decaying life all around, and
+the minute eggs of animals and spores of plants; but besides these,
+the pool is full of minute living plants--small jelly masses with
+solid coats of flint which are moulded into most lovely shapes. Plants
+formed of jelly and flint! You will think I am joking, but I am not.
+These plants, called Diatoms, which live both in salt and fresh water,
+are single cells feeding and growing just like those we took from the
+water-butt, only that instead of a soft covering they build up a
+flinty skeleton. They are so small, that many of them must be
+magnified to fifty times their real size before you can even see them
+distinctly. Yet the skeletons of these almost invisible plants are
+carved and chiselled in the most delicate patterns. I showed you a
+group of these in our lecture on magic glasses, and now I have brought
+a few living ones that we may learn to know them. The diagram (Fig. 7)
+shows the chief forms you will see on the different slides.
+
+The first one, _Sacillaria paradoxa_ (_b_, Fig. 7), looks like a
+number of rods clinging one to another in a string, but each one of
+these is a single-celled plant with a jelly cell surrounding the
+flinty skeleton. You will see that they move to and fro over each
+other in the water.
+
+The next two forms, _a_ and _c_, look much more like plants, for the
+cells arrange themselves on a jelly stem, which by and by disappears,
+leaving only the separate flint skeletons. The last form, _d_, is
+something midway between the other forms, the separate cells hang on
+to each other and also on to a straight jelly stem.
+
+[Illustration: FIG. 8. A DIATOM (_Diatoma vulgare_) GROWING.
+
+_a, b,_ Flint skeleton inside the jelly-cell. _a, c_ and _d, b_, Two
+flint skeletons formed by new valves, _c_ and _d_, forming within the
+first skeleton.]
+
+Another species of Diatoma (Fig. 8) called _Diatoma vulgare_, is a
+very simple and common form, and will help to explain how these plants
+grow. The two flinty valves _a, b_ inside the cell are not quite the
+same size; the older one _a_ is larger than the younger one _b_ and
+fits over it like the cover of a pill-box. As the plant grows, the
+cell enlarges and forms two more valves, one _c_ fitting into the
+cover _a_, so as to make a complete box _ac_, and a second, _d_, back
+to back with _c_, fitting into the valve _b_, and making another
+complete _bd_. This goes on very rapidly, and in this plant each new
+cell separates as it is formed, and the free diatoms move about quite
+actively in the water.
+
+If you consider for a moment, you will see that, as the new valves
+always fit into the old ones, each must be smaller than the last, and
+so there comes a time when the valves have become too small to go on
+increasing. Then the plant must begin afresh. So the two halves of the
+last cell open, and throwing out their flinty skeletons, cover
+themselves with a thin jelly layer, and form a new cell which grows
+larger than any of the old ones. These, which are spore-cells, then
+form flinty valves inside, and the whole thing begins again.
+
+Now, though the plants themselves die, or become the food of minute
+animals, the flinty skeletons are not destroyed, but go on
+accumulating in the waters of the ponds, lakes, rivers, and seas, all
+over the world. Untold millions have no doubt crumbled to dust and
+gone back into the waters, but untold millions also have survived. The
+towns of Berlin in Europe and of Richmond in the United States are
+actually built upon ground called "infusorial earth," composed almost
+entirely of valves of these minute diatoms which have accumulated to a
+thickness of more than eighty feet! Those under Berlin are fresh-water
+forms, and must have lived in a lake, while those of Richmond belong
+to salt-water forms. Every inch of the ground under those cities
+represents thousands and thousands of living plants which flourished
+in ages long gone by, and were no larger than those you will see
+presently under the microscope.
+
+These are a very few of the microscopic inhabitants of my pond, but,
+as you will confuse them if I show you too many, we will conclude with
+two rather larger specimens, and examine them carefully. The first,
+called the Cydippe, is a lovely, transparent living ball, which I want
+to explain to you because it is so wondrously beautiful. The second,
+the Sea-mat or Flustra, looks like a crumpled drab-colored seaweed,
+but is really composed of many thousands of grottos, the homes of tiny
+sea-animals.
+
+[Illustration: FIG. 9. _Cydippe Pileus_.
+
+1, Animal with tentacles _t_, bearing small tendrils _t'_. 2, Body of
+animal enlarged. _m_, Mouth. _c_, Digestive cavity. _s_, Sac into
+which the tentacles are withdrawn. _p_, Bands with comb-like plates.
+3, Portion of a band enlarged to show the moving plates _p_.]
+
+Let us take the Cydippe first (1, Fig. 9). I have six here, each in a
+separate tumbler, and could have brought many more, for when I dipped
+my net in the pool yesterday such numbers were caught in it that I
+believe the retreating tide must just have left a shoal behind. Put a
+tumbler on the desk in front of you, and if the light falls well upon
+it you will see a transparent ball about the size of a large pea
+marked with eight bright bands, which begin at the lower end of the
+ball and reach nearly to the top, dividing the outside into sections
+like the ribs of a melon. The creature is so perfectly transparent
+that you can count all the eight bands.
+
+At the top of the ball is a slight bulge which is the mouth (_m_ 2,
+Fig. 9), and from it, inside the ball hangs a long bag or stomach,
+which opens below into a cavity, from which two canals branch out, one
+on each side, and these divide again into four canals which go one
+into each of the tubes running down the bands. From this cavity the
+food, which is digested in the stomach, is carried by the canals all
+over the body. The smaller tubes which branch out of these canals
+cannot be seen clearly without a very strong lens, and the only other
+parts you can discern in this transparent ball are two long sacs on
+each side of the lower end. These are the tentacle sacs, in which are
+coiled up the tentacles, which we shall describe presently. Lastly you
+can notice that the bands outside the globe are broader in the middle
+than at the ends, and are striped across by a number of ridges.
+
+In moving the tumblers the water has naturally been shaken, and the
+creature being alarmed will probably at first remain motionless. But
+very soon it will begin to play in the water, rising and falling, and
+swimming gracefully from side to side. Now you will notice a curious
+effect, for the bands will glitter and become tinged with prismatic
+colors, till, as it moves more and more rapidly these colors,
+reflected in the jelly, seem to tinge the whole ball with colors like
+those on a soap-bubble, while from the two sacs below come forth two
+long transparent threads like spun glass. At first these appear to be
+simple threads, but as they gradually open out to about four or five
+inches, smaller threads uncoil on each side of the line till there are
+about fifty on each line. These short tendrils are never still for
+long; as the main threads wave to and fro, some of the shorter ones
+coil up and hang like tiny beads, then these uncoil and others roll
+up, so that these graceful floating lines are never two seconds alike.
+
+We do not really know their use. Sometimes the creature anchors itself
+by them, rising and falling as they stretch out or coil up; but more
+often they float idly behind it in the water. At first you would
+perhaps think that they served to drive the ball through the water,
+but this is done by a special apparatus. The cross ridges which we
+noticed on the bands are really flat comb-like plates (_p_, Fig. 9),
+of which there are about twenty or thirty on each band; and these
+vibrate very rapidly, so that two hundred or more paddles drive the
+tiny ball through the water. This is the cause of the prismatic
+colors; for iridescent tints are produced by the play of light upon
+the glittering plates, as they incessantly change their angle.
+Sometimes they move all at once, sometimes only a few at a time, and
+it is evident the creature controls them at will.
+
+This lovely fairy-like globe, with its long floating tentacles and
+rainbow tints, was for a long time classed with the jelly-fish; but it
+really is most nearly related to the sea-anemones, as it has a true
+central cavity which acts as a stomach, and many other points in
+common with the _Actinozoa_. We cannot help wondering, as the little
+being glides hither and thither, whether it can see where it is going.
+It has nerves of a low kind which start from a little dark spot (_ng_)
+exactly at the south pole of the ball, and at that point a sense-organ
+of some kind exists, but what impression the creature gains from it of
+the world outside we cannot tell.
+
+I am afraid you may think it dull to turn from such a beautiful being
+as this, to the gray leaf which looks only like a dead dry seaweed;
+yet you will be wrong, for a more wonderful history attaches to this
+crumpled dead-looking leaf than to the lovely jelly-globe.
+
+[Illustration: FIG. 10. THE SEA-MAT OR FLUSTRA (_Flustra foliacea_).
+
+1, Natural size. 2, Much magnified, _s_, Slit caused by drawing in of
+the animal _a_.]
+
+First of all I will pass round pieces of the dry leaf (1, Fig. 10),
+and while you are getting them I will tell you where I found the
+living ones. Great masses of the Flustra, as it is called, line the
+bottom and sides of my pool. They grow in tufts, standing upright on
+the rock, and looking exactly like hard gray seaweeds, while there is
+nothing to lead you to suspect that they are anything else. Yesterday
+I chipped off very carefully a piece of rock with a tuft upon it, and
+have kept it since in a glass globe by itself with sea-water, for the
+little creatures living in this marine city require a very good supply
+of healthy water and air. I have called it a "marine city," and now I
+will tell you why. Take the piece in your hand and run your finger
+gently up and down it; you will glide quite comfortably from the lower
+to the higher part of the leaf, but when you come back you will feel
+your finger catch slightly on a rough surface. Your pocket lens will
+show you why this is, for if you look through it at the surface of the
+leaf you will see it is not smooth, but composed of hundreds of tiny
+alcoves with arched tops; and on each side of these tops stand two
+short blunt spines, making four in all, pointing upwards, so as partly
+to cover the alcove above. As your finger went up it glided over the
+spines, but on coming back it met their points. This is all you can
+see in the dead specimen; I must show you the rest by diagrams, and by
+and by under the microscope.
+
+First, then, in the living specimen which I have here, those alcoves
+are not open as in the dead piece, but covered over with a transparent
+skin, in which, near the top of the alcove just where the curve
+begins, is a slit (_s_ 2, Fig. 10) Unfortunately, the membrane
+covering this alcove is too dense for you to distinguish the parts
+within. Presently, however, if you are watching a piece of this living
+leaf in a flat water-cell under the microscope, you will see the slit
+slowly open, and begin to turn as it were inside out, exactly like the
+finger of a glove, which has been pushed in at the tip, gradually
+rises up when you put your finger inside it. As this goes on, a bundle
+of threads appears, at first closed like a bud, but gradually opening
+out into a crown of tentacles, each one clothed with hairs. Then you
+will see that the slit was not exactly a slit after all, but the round
+edge where the sac was pushed in. Ah! you will say, you are now
+showing me a polyp like those on the sertularian tree. Not so fast, my
+friend; you have not studied what is still under the covering skin and
+hidden in the living animal. I have, however, prepared a slide with
+this membrane removed and there you can observe the different parts,
+and learn that each one of these alcoves contains a complete animal,
+and not merely one among many mouths, like the polyp on Sertularia.
+
+[Illustration: FIG. 11. DIAGRAM OF THE ANIMAL IN THE FLUSTRA OR
+SEA-MAT.
+
+1, Animal protruding. 2, Animal retracted in the sheath, _sh_,
+Covering sheath, _s_, Slit. _t_, Tentacles. _m_, Mouth. _th_, Throat,
+_st_, Stomach. _i_, Intestine, _r_, Retractor muscle, _e_, Egg-forming
+parts. _g_, Nerve-ganglion.]
+
+Each of these little beings (_a_, Fig. 10) living in its alcove has a
+mouth, throat, stomach, intestine, muscles, and nerves starting from
+the ganglion of nervous matter, besides all that is necessary for
+producing eggs and sending forth young ones. You can trace all these
+under the microscope (see 2, Fig. 11) as the creature lies curiously
+doubled up in its bed, with its body bent in a loop; the intestine
+_i_, out of which the refuse food passes, coming back close up to the
+slit. When it is at rest, the top of the sac in which it lies is
+pulled in by the retractor muscle _r_, and looks, as I have said, like
+the finger of a glove with the top pushed in. When it wishes to feed
+this top is drawn out by muscles running round the sac, and the
+tentacles open and wave in the water (1, Fig. 11).
+
+Look now at the alcoves, the homes of these animals; see how tiny they
+are and how closely they fit together. Mr. Gosse, the naturalist, has
+reckoned that there are six thousand, seven hundred and twenty alcoves
+in a square inch; then if you turn the leaf over you will see that
+there is another set, fixed back to back with these, on the other
+side, making in all, thirteen thousand, four hundred and forty
+alcoves. Now a moderate-sized leaf of flustra measures about three
+square inches, taking all the rounded lobes into account, so you will
+see we get forty thousand, three hundred and twenty as a rough
+estimate of the number of beings on this one leaf. But if you look at
+this tuft I have brought, you will find it is composed of twelve such
+leaves, and this after all is a very small part of the mass growing
+round my pool. Was I wrong, then, when I said my miniature ocean
+contains as many millions of beings as there are stars in the heavens?
+
+You will want to know how these leaves grew, and it is in this way.
+First a little free swimming animal, a mere living sac provided with
+lashes, settles down and grows into one little horny alcove, with its
+live creature inside, which in time sends off from it three to five
+buds, forming alcoves all round the top and sides of the first one,
+growing on to it. These again bud out, and you can thus easily
+understand that, in this way, in time a good-sized leaf is formed.
+Meanwhile the creatures also send forth new swimming cells, which
+settle down near to begin new leaves, and thus a tuft is formed; and
+long after the beings in earlier parts of the leaf have died and left
+their alcoves empty, those round the margin are still alive and
+spreading....
+
+If you can trace the spore-cells and urns in the seaweeds, observe the
+polyps in the Sertularia, and count the number of mouths on a branch
+of my animal fringe (Sertularia tenella); if you make acquaintance
+with the Thuricolla in its vase, and are fortunate enough to see one
+divide in two; if you learn to know some of the beautiful forms of
+diatoms, and can picture to yourself the life of the tiny inhabitants
+of the Flustra; then you will have used your microscope with some
+effect, and be prepared for an expedition to my pool, where we will go
+together some day to seek new treasures.
+
+[Illustration]
+
+
+
+
+NOTES
+
+
+AGASSIZ, J.L.R., naturalist, born in Switzerland, 1807; died,
+Cambridge, Mass., 1873. In 1846 he came to America, after having
+gained a high reputation in Europe, to deliver a course of lectures in
+Boston "On the Plan of the Creation," and met with such success that
+he spent the rest of his days there, declining an invitation to return
+to his native country and to Paris. In 1848 he was elected to the
+chair of Natural History at Harvard. In 1850-51 he went on an
+expedition to the Florida Reefs. In 1858 he founded and organized the
+Museum of Comparative Zooelogy at Cambridge--and, later on, went on his
+important voyage to Brazil. In 1872 he founded and organized the
+summer school of Natural History at Buzzard's Bay. He wrote "The
+Fishes of Brazil," "A Study of Glaciers," "Natural History of the
+Fresh Water Fishes of Central Europe," "Contributions to the Natural
+History of the United States" (unfinished), and with his wife, "A
+Journey in Brazil."
+
+BALL, PROF. SIR R.S., English astronomer, born in Dublin, 1840. Was
+appointed Lord Ross's astronomer in 1865. Professor of mathematics and
+mechanics at the Royal Irish College of Science in 1873, and is now
+astronomer royal for Ireland. He is the author of "The Story of the
+Heavens," "Starland," etc., and is well known as a successful lecturer
+on astronomical subjects in this country.
+
+DARWIN, CHARLES R., English naturalist, born, 1809; died, 1882. He
+first formulated what is known as the principle of Natural Selection.
+In 1831 he went in the famous scientific voyage of the _Beagle_ as
+naturalist, and afterwards published an account of it. He was one of
+the most thorough, careful, and painstaking scientific men of this or
+any age. He is the author of many famous books. "The Origin of
+Species," "The Descent of Man," "Insectivorous Plants," "The Power of
+Movement in Plants," "The Structure and Distribution of Coral Reefs,"
+"Geological Observations on Volcanic Islands." "The Formation of
+Vegetable Mould" was his last published work.
+
+FLAMMARION, C., famous French astronomer, born, 1842. He has written
+many popular works on astronomy, most of which have been translated
+into English. "The Stars," "The World Before the Creation," "Uranus,"
+"Comets," "Popular Astronomy," are among his best known.
+
+HOLDEN, PROF. E.S., American astronomer, born at St. Louis, 1846.
+Lieutenant engineers, U.S.A., 1870-73; professor mathematics, U.S.N.,
+1873-81; director Washburn Observatory, 1881-85; president University
+of California, 1883-88; director Lick Observatory, 1888-98. Is a
+member of several learned societies of Europe. Is the author of a
+"Life of William Herschel," "A Hand-book of the Lick Observatory,"
+"Earth and Sky," "Primer of Heraldry," "Elementary Astronomy," "Family
+of the Sun," "Essays in Astronomy," "Stories of the Great
+Astronomers," etc.
+
+HUXLEY, T.H., English biologist, born, 1825; died, 1895. Went on an
+exploring expedition on the _Rattlesnake_, and devoted himself to the
+study of marine life. For his scientific researches he received many
+honors. His lectures were models of clearness, and he could simplify
+the most difficult subjects. He strongly advocated Darwin's views and
+evolutionist doctrines. His writings are numerous and many of them
+technical. Among some of the most popular are "Man's Place in Nature,"
+his "Lay Sermons," "Critiques and Addresses," "American Addresses,"
+"Physiography," "Science and Culture," "Lessons in Elementary
+Physiology," etc.
+
+KINGSLEY, C., English clergyman and author, born, 1819; died, 1875.
+Wrote "Westward, Ho!" which every boy should read, "Hypatia," "Alton
+Locke," "Hereward the Wake," etc., and a charming book of travel,
+entitled, "At Last." His "Water Babies" is exceedingly popular, and
+his "Heroes" is a book much appreciated by the boys and girls alike.
+
+PROCTOR, R.A., English astronomer, born, 1834; died, 1888. He was a
+very popular writer, and lectured on astronomical subjects in this
+country, and in England and her colonies. A memorial teaching
+observatory is erected in his honor near San Diego, Cal. He was a man
+of untiring industry, an athlete, a musician, and a chess-player. His
+books are numerous. Among them are "Half Hours with the Telescope,"
+"Other Worlds than Ours," "Light Science for Leisure Hours," "The
+Expanse of Heaven," "The Moon," "The Borderland of Science," "Our
+Place Among Infinites," "Myths and Marvels of Astronomy," "The
+Universe of Suns," "Other Suns than Ours," etc.
+
+SHALER, N.S., professor of geology at Harvard. Born Newport, Ky.,
+1841. Served in the Union Army during the Civil War. Instructor
+zooelogy, geology, and paleontology, Lawrence Scientific School, till
+1887. Since then at Harvard. Is the author of "Kentucky a Pioneer
+Commonwealth," "The Story of Our Continent," "The Interpretation of
+Nature," "Feature of Coasts and Oceans," "Domesticated Animals," "The
+Individual," "Study of Life and Death," etc.
+
+THOMPSON, SIR C. WYVILLE, English zooelogist, born, 1830; died, 1882.
+He conducted scientific dredging expeditions in the _Lightning_ and
+_Porcupine_, 1868-69, and was the scientific head of the famous voyage
+of 68,900 miles in the _Challenger_ for deep-sea explorations
+(1872-76). His books are "The Depths of the Sea," and "The Voyage of
+the Challenger."
+
+TYNDALL, JOHN, English physicist, born, 1820. Began his original
+researches in 1847, when teacher of physics in Queenwood College. He
+and Professor Huxley visited the Alps together, and they wrote a work
+on the structure and nature of glaciers. It is impossible to detail
+the work he has done; but his inquiries and experiments in connection
+with light, heat, sound, and electricity have all had practical
+results. He is a popular lecturer, and devoted the proceeds of a
+lecturing tour in this country to founding scholarships at Harvard and
+Columbia Colleges, for students devoting themselves to original
+research. Among his books are "Glaciers of the Alps," "Mountaineering,"
+"Heat as a Mode of Motion," "On Radiation," "Hours of Exercise in the
+Alps," "Fragments of Science," "The Floating Matter of the Air," and
+volumes on Light, Sound, Electricity, and the forms of water.
+
+WALLACE, A.R., English naturalist and traveller, born 1822; was
+educated as land surveyor and architect, but afterwards devoted
+himself entirely to Natural History. He explored the Valley of the
+Amazon and Rio Negro, 1848-52, and travelled in the Malay Archipelago
+and Papua, 1854-62, publishing the results of his explorations later
+on. He also wrote "Contributions to the Theory of Natural Selection,"
+"Miracles and Modern Spiritualism," "Geographical Distribution of
+Animals," "Tropical Nature," "Island Life," etc.
+
+GIBERNE, AGNES, English author--living. Began to write at seven years
+old. Her first story for children was published when she was only
+seventeen. Her stories for children have not been so popular as her
+scientific writings, "Sun, Moon, and Stars," "The Starry Skies,"
+"Among the Stars," "The Ocean of Air," "The World's Foundations,"
+"Radiant Suns," etc.
+
+WILSON, ANDREW, English physiologist and lecturer, born, 1852. Is the
+author of "Studies on Life and Sense," "Leisure Time Studies,"
+"Science Stories," "Chapters on Evolution," "Wild Animals," "Brain and
+Nerve," etc., and is a constant contributor on scientific subjects to
+the magazines and newspapers, contributing weekly "Science Jottings"
+to the "Illustrated London News"
+
+
+
+
+WONDERS OF EARTH, SEA, AND SKY
+
+SUGGESTIONS FOR SUPPLEMENTARY READING
+
+
+  Wonder Stories of Science
+    D.N. BEACH
+
+  Wonders in Monsterland
+    EDWARD W.D. CUMING
+
+  Ocean Wonders
+    W.E. DAMON
+
+  Among the Stars
+    AGNES GIBERNE
+
+  The Scenery of the Heavens
+    JOHN ELLARD GORR
+
+  Coal and the Coal Miners
+    HOMER GREENE
+
+  Wonders of the Moon
+    A. GUILLEMIN
+
+  The Sea and Its Living Wonders.
+    G. HARTWIG
+
+  The Wonders of Plant Life Under the Microscope
+    SOPHIE B. HERRICK
+
+  Marvels of Animal Life
+    CHARLES F. HOLDER
+
+  Old Ocean
+    ERNEST INGERSOLL
+
+  Modern Seven Wonders of the World
+    C. KENT
+
+  Madam How and Lady Why
+    CHARLES KINGSLEY
+
+  Wonders of Optics
+    F. MARION
+
+  The Wonders of Science
+    HENRY MAYHEW
+
+  Wonders of Man and Nature
+    E. MENAULT
+
+  A Century of Electricity
+    T.C. MENDENHALL
+
+  The Orbs of Heaven
+    ORMSBY S. MITCHELL
+
+  Under Foot
+    LAURA D. NICHOLS
+
+  Myths and Marvels of Astronomy
+    R.A. PROCTOR
+
+  The Wonders of the World
+    CHARLES G. ROSENBERG
+
+  The Wonders of Nature
+    PROFESSOR RUDOLPH
+
+  Volcanoes of North America
+    ISRAEL COOK RUSSELL
+
+  Aspects of the Earth
+    N.S. SHALER
+
+  Wonders of the Bird World
+    R.B. SHARPE
+
+  The Wonders of Water
+    GASTON TISSANDIER
+
+  Total Eclipses of the Sun
+    MABEL L. TODD
+
+  Wonders of Insect Life
+    JOSEPH C. WILLET
+
+
+
+***END OF THE PROJECT GUTENBERG EBOOK YOUNG FOLKS' LIBRARY, VOLUME XI (OF
+20)***
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