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-Project Gutenberg's Curiosities of Science, Past and Present, by John Timbs

-

-This eBook is for the use of anyone anywhere in the United States and most

-other parts of the world 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.  If you are not located in the United States, you'll have

-to check the laws of the country where you are located before using this ebook.

-

-Title: Curiosities of Science, Past and Present

-       A Book for Old and Young

-

-Author: John Timbs

-

-Release Date: March 17, 2015 [EBook #48516]

-

-Language: English

-

-Character set encoding: UTF-8

-

-*** START OF THIS PROJECT GUTENBERG EBOOK CURIOSITIES OF SCIENCE, PAST, PRESENT ***

-

-

-

-

-Produced by Chris Curnow, Charlie Howard, and the Online

-Distributed Proofreading Team at http://www.pgdp.net (This

-file was produced from images generously made available

-by The Internet Archive)

-

-

-

-

-

-

-

-

-

-    NEW WORK ON PAINTING.

-

-    _Just ready, in small 8vo, with Frontispiece and Vignette_,

-

-    PAINTING

-    POPULARLY EXPLAINED;

-

-    WITH

-    The Practice of the Art,

-    AND

-    HISTORICAL NOTICES OF ITS PROGRESS.

-

-    BY

-    THOMAS J. GULLICK, PAINTER,

-    AND

-    JOHN TIMBS, F.S.A.

-

-

-The plan of this work is thus sketched in the _Introduction_:

-

-  “There have been in the history of Art, four grand styles of

-  imitating Nature--Tempera, Encaustic, Fresco, and Oil. These,

-  together with the minor modes of Painting, we propose arranging

-  in something like chronological sequence; but our design being

-  to offer an explanation of the Art derived from practical

-  acquaintance, rather than attempt to give its history, we shall

-  confine ourselves for the most part to so much only of the History

-  of Painting as is necessary to elucidate the origin of the

-  different practices which have obtained at different periods.”

-

-  By this means, the Authors hope to produce a work which may be

-  valuable to the Amateur, and interesting to the Connoisseur, the

-  Artist, and the General Reader.

-

-

-LONDON: KENT & CO. (LATE BOGUE), FLEET STREET.

-

-[Illustration: MOUTH OF THE GREAT ROSSE TELESCOPE, AT PARSONSTOWN.

-

-FROM A PHOTOGRAPH.]

-

-

-

-

-    Things not generally Known

-    Familiarly Explained.

-

-

-    CURIOSITIES OF SCIENCE,

-

-    Past and Present.

-

-    A BOOK FOR OLD AND YOUNG.

-

-

-    BY JOHN TIMBS, F.S.A.

-

-    AUTHOR OF THINGS NOT GENERALLY KNOWN; AND EDITOR OF THE

-    YEAR-BOOK OF FACTS.

-

-    [Illustration: Model of the Safety-Lamp, made by Sir Humphry

-       Davy’s own hands; in the possession of the Royal Society.]

-

-

-    LONDON:

-    KENT AND CO. (LATE BOGUE), FLEET STREET.

-    MDCCCLVIII.

-

-

-

-

-    _The Author reserves the right of authorising a Translation of

-    this Work._

-

-

-    LONDON:

-    PRINTED BY LEVEY, ROBSON, AND FRANKLYN,

-    Great New Street and Fetter Lane.

-

-

-

-

-GENTLE READER,

-

-The volume of “CURIOSITIES” which I here present to your notice is a

-portion of the result of a long course of reading, observation, and

-research, necessary for the compilation of thirty volumes of “Arcana

-of Science” and “Year-Book of Facts,” published from 1828 to 1858.

-Throughout this period--nearly half of the Psalmist’s “days of our

-years”--I have been blessed with health and strength to produce these

-volumes, year by year (with one exception), upon the appointed day; and

-this with unbroken attention to periodical duties, frequently rendered

-harassing or ungenial. Nevertheless, during these three decades I

-have found my account in the increasing approbation of the reading

-public, which has been so largely extended to the series of “THINGS

-NOT GENERALLY KNOWN,” of which the present volume of “CURIOSITIES OF

-SCIENCE” is an instalment. I need scarcely add, that in its progressive

-preparation I have endeavoured to compare, weigh, and consider,

-the contents, so as to combine the experience of the Past with the

-advantages of the Present.

-

-In these days of universal attainments, when Science becomes not

-merely a luxury to the rich, but bread to the poor, and when the

-very amusements as well as the conveniences of life have taken a

-scientific colour, it is reasonable to hope that the present volume

-may be acceptable to a large class of seekers after “things not

-generally known.” For this purpose, I have aimed at soundness as well

-as popularity; although, for myself, I can claim little beyond being

-one of those industrious “ants of science” who garner facts, and by

-selection and comparison adapt them for a wider circle of readers

-than they were originally expected to reach. In each case, as far as

-possible, these “CURIOSITIES” bear the mint-mark of authority; and in

-the living list are prominent the names of Humboldt and Herschel, Airy

-and Whewell, Faraday, Brewster, Owen, and Agassiz, Maury, Wheatstone,

-and Hunt, from whose writings and researches the following pages are

-frequently enriched.

-

-The sciences here illustrated are, in the main, Astronomy and

-Meteorology; Geology and Paleontology; Physical Geography; Sound,

-Light, and Heat; Magnetism and Electricity,--the latter with special

-attention to the great marvel of our times, the Electro-magnetic

-Telegraph. I hope, at no very distant period, to extend the

-“CURIOSITIES” to another volume, to include branches of Natural and

-Experimental Science which are not here presented.

-

-            I. T.

-    _November 1858._

-

-

-

-

-CONTENTS.

-

-

-                                          PAGE

-    INTRODUCTORY                          1-10

-

-    PHYSICAL PHENOMENA                   11-26

-

-    SOUND AND LIGHT                      27-53

-

-    ASTRONOMY                           54-103

-

-    GEOLOGY AND PALEONTOLOGY           104-145

-

-    METEOROLOGICAL PHENOMENA           146-169

-

-    PHYSICAL GEOGRAPHY OF THE SEA      170-192

-

-    MAGNETISM AND ELECTRICITY          193-219

-

-    THE ELECTRIC TELEGRAPH             220-228

-

-    MISCELLANEA                        229-241

-

-

-

-

-The Frontispiece.

-

-THE GREAT ROSSE TELESCOPE.

-

-

-The originator and architect of this magnificent instrument had long

-been distinguished in scientific research as Lord Oxmantown; and

-may be considered to have gracefully commemorated his succession to

-the Earldom of Rosse, and his Presidency of the Royal Society, by

-the completion of this marvellous work, with which his name will be

-hereafter indissolubly associated.

-

-The Great Reflecting Telescope at Birr Castle (of which the

-Frontispiece represents a portion[1]) will be found fully described at

-pp. 96-99 of the present volume of _Curiosities of Science_.

-

-This matchless instrument has already disclosed “forms of stellar

-arrangement indicating modes of dynamic action never before

-contemplated in celestial mechanics.” “In these departments of

-research,--the examination of the configurations of nebulæ, and the

-resolution of nebulæ into stars (says the Rev. Dr. Scoresby),--the

-six-feet speculum has had its grandest triumphs, and the noble

-artificer and observer the highest rewards of his talents and

-enterprise. Altogether, the quantity of work done during a period of

-about seven years--including a winter when a noble philanthropy for

-a starving population absorbed the keenest interests of science--has

-been decidedly great; and the new knowledge acquired concerning the

-handiwork of the great Creator amply satisfying of even sanguine

-expectation.”

-

-

-

-

-The Vignette.

-

-SIR HUMPHRY DAVY’S OWN MODEL OF HIS SAFETY-LAMP.

-

-

-Of the several contrivances which have been proposed for safely

-lighting coal-mines subject to the visitation of fire-damp, or

-carburetted hydrogen, the Safety-Lamp of Sir Humphry Davy is the only

-one which has ever been judged safe, and been extensively employed. The

-inventor first turned his attention to the subject in 1815, when Davy

-began a minute chemical examination of fire-damp, and found that it

-required an admixture of a large quantity of atmospheric air to render

-it explosive. He then ascertained that explosions of inflammable gases

-were incapable of being passed through long narrow metallic tubes, and

-that this principle of security was still obtained by diminishing their

-length and increasing their number. This fact led to trials upon sieves

-made of wire-gauze; when Davy found that if a piece of wire-gauze was

-held over the flame of a lamp, or of coal-gas, it prevented the flame

-from passing; and he ascertained that a flame confined in a cylinder of

-very fine wire-gauze did not explode even in a mixture of oxygen and

-hydrogen, but that the gases burnt in it with great vivacity.

-

-These experiments served as the basis of the Safety-Lamp. The apertures

-in the gauze, Davy tells us in his work on the subject, should not

-be more than 1/22d of an inch square. The lamp is screwed on to the

-bottom of the wire-gauze cylinder. When it is lighted, and gradually

-introduced into an atmosphere mixed with fire-damp, the size and length

-of the flame are first increased. When the inflammable gas forms as

-much as 1/12th of the volume of air, the cylinder becomes filled with a

-feeble blue flame, within which the flame of the wick burns brightly,

-and the light of the wick continues till the fire-damp increases to

-1/6th or 1/5th; it is then lost in the flame of the fire-damp, which

-now fills the cylinder with a pretty strong light; and when the foul

-air constitutes one-third of the atmosphere it is no longer fit for

-respiration,--and this ought to be a signal to the miner to leave that

-part of the workings.

-

-Sir Humphry Davy presented his first communication respecting his

-discovery of the Safety-Lamp to the Royal Society in 1815. This was

-followed by a series of papers remarkable for their simplicity and

-clearness, crowned by that read on the 11th of January 1816, when the

-principle of the Safety-Lamp was announced, and Sir Humphry presented

-to the Society a model made by his own hands, which is to this day

-preserved in the collection of the Royal Society at Burlington House.

-From this interesting memorial the Vignette has been sketched.

-

-There have been several modifications of the Safety-Lamp, and the merit

-of the discovery has been claimed by others, among whom was Mr. George

-Stephenson; but the question was set at rest forty-one years since by

-an examination,--attested by Sir Joseph Banks, P.R.S., Mr. Brande, Mr.

-Hatchett, and Dr. Wollaston,--and awarding the independent merit to

-Davy.

-

-A more substantial, though not a more honourable, testimony of approval

-was given by the coal-owners, who subscribed 2500_l._ to purchase a

-superb service of plate, which was suitably inscribed and presented to

-Davy.[2]

-

-Meanwhile the Report by the Parliamentary Committee “cannot admit that

-the experiments (made with the Lamp) have any tendency to detract from

-the character of Sir Humphry Davy, or to disparage the fair value

-placed by himself upon his invention. The improvements are probably

-those which longer life and additional facts would have induced him to

-contemplate as desirable, and of which, had he not been the inventor,

-he might have become the patron.”

-

-The principle of the invention may be thus summed up. In the

-Safety-Lamp, the mixture of the fire-damp and atmospheric air within

-the cage of wire-gauze explodes upon coming in contact with the flame;

-but the combustion cannot pass through the wire-gauze, and being there

-imprisoned, cannot impart to the explosive atmosphere of the mine any

-of its force. This effect has been erroneously attributed to a cooling

-influence of the metal.

-

-Professor Playfair has eloquently described the Safety-Lamp of Davy as

-a present from philosophy to the arts; a discovery in no degree the

-effect of accident or chance, but the result of patient and enlightened

-research, and strongly exemplifying the great use of an immediate and

-constant appeal to experiment. After characterising the invention as

-the _shutting-up in a net of the most slender texture_ a most violent

-and irresistible force, and a power that in its tremendous effects

-seems to emulate the lightning and the earthquake, Professor Playfair

-thus concludes: “When to this we add the beneficial consequences, and

-the saving of the lives of men, and consider that the effects are to

-remain as long as coal continues to be dug from the bowels of the

-earth, it may be fairly said that there is hardly in the whole compass

-of art or science a single invention of which one would rather wish

-to be the author.... This,” says Professor Playfair, “is exactly such

-a case as we should choose to place before Bacon, were he to revisit

-the earth; in order to give him, in a small compass, an idea of the

-advancement which philosophy has made since the time when he had

-pointed out to her the route which she ought to pursue.”

-

-

-

-

-CURIOSITIES OF SCIENCE.

-

-

-

-

-Introductory.

-

-

-SCIENCE OF THE ANCIENT WORLD.

-

-In every province of human knowledge where we now possess a careful

-and coherent interpretation of nature, men began by attempting in

-bold flights to leap from obvious facts to the highest point of

-generality--to some wide and simple principle which after-ages had to

-reject. Thus, from the facts that all bodies are hot or cold, moist or

-dry, they leapt at once to the doctrine that the world is constituted

-of four elements--earth, air, fire, water; from the fact that the

-heavenly bodies circle the sky in courses which occur again and again,

-they at once asserted that they move in exact circles, with an exactly

-uniform motion; from the fact that heavy bodies fall through the air

-somewhat faster than light ones, it was assumed that all bodies fall

-quickly or slowly exactly in proportion to their weight; from the fact

-that the magnet attracts iron, and that this force of attraction is

-capable of increase, it was inferred that a perfect magnet would have

-an irresistible force of attraction, and that the magnetic pole of

-the earth would draw the nails out of a ship’s bottom which came near

-it; from the fact that some of the finest quartz crystals are found

-among the snows of the Alps, it was inferred that the crystallisation

-of gems is the result of intense and long-continued cold: and so on

-in innumerable instances. Such anticipations as these constituted

-the basis of almost all the science of the ancient world; for such

-principles being so assumed, consequences were drawn from them with

-great ingenuity, and systems of such deductions stood in the place of

-science.--_Edinburgh Review_, No. 216.

-

-

-SCIENCE AT OXFORD AND CAMBRIDGE.

-

-The earliest science of a decidedly English school is due, for the most

-part, to the University of Oxford, and specially to Merton College,--a

-foundation of which Wood remarks, that there was no other for two

-centuries, either in Oxford or Paris, which could at all come near it

-in the cultivation of the sciences. But he goes on to say that large

-chests full of the writers of this college were allowed to remain

-untouched by their successors for fear of the magic which was supposed

-to be contained in them. Nevertheless, it is not difficult to trace

-the liberalising effect of scientific study upon the University in

-general, and Merton College in particular; and it must be remembered

-that to the cultivation of the mind at Oxford we owe almost all the

-literary celebrity of the middle ages. In this period the University of

-Cambridge appears to have acquired no scientific distinction. Taking

-as a test the acquisition of celebrity on the continent, we find that

-Bacon, Sacrobosco, Greathead, Estwood, &c. were all of Oxford. The

-latter University had its morning of splendour while Cambridge was

-comparatively unknown; it had also its noonday, illustrated by such men

-as Briggs, Wren, Wallis, Halley, and Bradley.

-

-The age of science at Cambridge may be said to have begun with Francis

-Bacon; and but that we think much of the difference between him and

-his celebrated namesake lies more in time and circumstances than in

-talents or feelings, we would rather date from 1600 with the former

-than from 1250 with the latter. Praise or blame on either side is out

-of the question, seeing that the earlier foundation of Oxford, and its

-superiority in pecuniary means, rendered all that took place highly

-probable; and we are in a great measure indebted for the liberty of

-writing our thoughts, to the cultivation of the liberalising sciences

-at Oxford in the dark ages.

-

-With regard to the University of Cambridge, for a long time there

-hardly existed the materials of any proper instruction, even to the

-extent of pointing out what books should be read by a student desirous

-of cultivating astronomy.

-

-

-PLATO’S SURVEY OF THE SCIENCES.

-

-  Plato, like Francis Bacon, took a review of the sciences of his

-  time: he enumerates arithmetic and plane geometry, treated as

-  collections of abstract and permanent truths; solid geometry, which

-  he “notes as deficient” in his time, although in fact he and his

-  school were in possession of the doctrine of the “five regular

-  solids;” astronomy, in which he demands a science which should

-  be elevated above the mere knowledge of phenomena. The visible

-  appearances of the heavens only suggest the problems with which

-  true astronomy deals; as beautiful geometrical diagrams do not

-  prove, but only suggest geometrical propositions. Finally, Plato

-  notices the subject of harmonics, in which he requires a science

-  which shall deal with truths more exact than the ear can establish,

-  as in astronomy he requires truths more exact than the eye can

-  assure us of.

-

-  In a subsequent paper Plato speaks of _Dialectic_ as a still

-  higher element of a philosophical education, fitted to lead men

-  to the knowledge of real existences and of the supreme good. Here

-  he describes dialectic by its objects and purpose. In other places

-  dialectic is spoken of as a method or process of analysis; as in

-  the _Phædrus_, where Socrates describes a good dialectician as one

-  who can divide a subject according to its natural members, and not

-  miss the joint, like a bad carver. Xenophon says that Socrates

-  derived _dialectic_ from a term implying to _divide a subject into

-  parts_, which Mr. Grote thinks unsatisfactory as an etymology, but

-  which has indicated a practical connection in the Socratic school.

-  The result seems to be that Plato did not establish any method of

-  analysis of a subject as his dialectic; but he conceived that the

-  analytical habits formed by the comprehensive study of the exact

-  sciences, and sharpened by the practice of dialogue, would lead his

-  students to the knowledge of first principles.--_Dr. Whewell._

-

-

-FOLLY OF ATHEISM.

-

-Morphology, in natural science, teaches us that the whole animal

-and vegetable creation is formed upon certain fundamental types

-and patterns, which can be traced under various modifications and

-transformations through all the rich variety of things apparently of

-most dissimilar build. But here and there a scientific person takes

-it into his foolish head that there may be a set of moulds without

-a moulder, a calculated gradation of forms without a calculator, an

-ordered world without an ordering God. Now, this atheistical science

-conveys about as much meaning as suicidal life: for science is possible

-only where there are ideas, and ideas are only possible where there is

-mind, and minds are the offspring of God; and atheism itself is not

-merely ignorance and stupidity,--it is the purely nonsensical and the

-unintelligible.--_Professor Blackie_; _Edinburgh Essays_, 1856.

-

-

-THE ART OF OBSERVATION.

-

-To observe properly in the very simplest of the physical sciences

-requires a long and severe training. No one knows this so feelingly

-as the great discoverer. Faraday once said, that he always doubts his

-own observations. Mitscherlich on one occasion remarked to a man of

-science that it takes fourteen years to discover and establish a single

-new fact in chemistry. An enthusiastic student one day betook himself

-to Baron Cuvier with the exhibition of a new organ--a muscle which he

-supposed himself to have discovered in the body of some living creature

-or other; but the experienced and sagacious naturalist kindly bade the

-young man return to him with the same discovery in six months. The

-Baron would not even listen to the student’s demonstration, nor examine

-his dissection, till the eager and youthful discoverer had hung over

-the object of inquiry for half a year; and yet that object was a mere

-thing of the senses.--_North-British Review_, No. 18.

-

-

-MUTUAL RELATIONS OF PHENOMENA.

-

-In the observation of a phenomenon which at first sight appears to

-be wholly isolated, how often may be concealed the germ of a great

-discovery! Thus, when Galvani first stimulated the nervous fibre of

-the frog by the accidental contact of two heterogeneous metals, his

-contemporaries could never have anticipated that the action of the

-voltaic pile would discover to us in the alkalies metals of a silver

-lustre, so light as to swim on water, and eminently inflammable; or

-that it would become a powerful instrument of chemical analysis, and at

-the same time a thermoscope and a magnet. When Huyghens first observed,

-in 1678, the phenomenon of the polarisation of light, exhibited in the

-difference between two rays into which a pencil of light divides itself

-in passing through a doubly refracting crystal, it could not have been

-foreseen that a century and a half later the great philosopher Arago

-would, by his discovery of _chromatic polarisation_, be led to discern,

-by means of a small fragment of Iceland spar, whether solar light

-emanates from a solid body or a gaseous covering; or whether comets

-transmit light directly, or merely by reflection.--_Humboldt’s Cosmos_,

-vol. i.

-

-

-PRACTICAL RESULTS OF THEORETICAL SCIENCE.

-

-What are the great wonders, the great sources of man’s material

-strength, wealth, and comfort in modern times? The Railway, with its

-mile-long trains of men and merchandise, moving with the velocity of

-the wind, and darting over chasms a thousand feet wide; the Electric

-Telegraph, along which man’s thoughts travel with the velocity of

-light, and girdle the earth more quickly than Puck’s promise to his

-master; the contrivance by which the Magnet, in the very middle of

-a strip of iron, is still true to the distant pole, and remains a

-faithful guide to the mariner; the Electrotype process, by which a

-metallic model of any given object, unerringly exact, grows into

-being like a flower. Now, all these wonders are the result of recent

-and profound discoveries in theoretical science. The Locomotive

-Steam-engine, and the Steam-engine in all its other wonderful and

-invaluable applications, derives its efficacy from the discoveries, by

-Watt and others, of the laws of steam. The Railway Bridge is not made

-strong by mere accumulation of materials, but by the most exact and

-careful scientific examination of the means of giving the requisite

-strength to every part, as in the great example of Mr. Stephenson’s

-Britannia Bridge over the Menai Strait. The Correction of the Magnetic

-Needle in iron ships it would have been impossible for Mr. Airy to

-secure without a complete theoretical knowledge of the laws of

-Magnetism. The Electric Telegraph and the Electrotype process include

-in their principles and mechanism the most complete and subtle results

-of electrical and magnetical theory.--_Edinburgh Review_, No. 216.

-

-

-PERPETUITY OF IMPROVEMENT.

-

-In the progress of society all great and real improvements are

-perpetuated: the same corn which, four thousand years ago, was raised

-from an improved grass by an inventor worshiped for two thousand years

-in the ancient world under the name of Ceres, still forms the principal

-food of mankind; and the potato, perhaps the greatest benefit that the

-old has derived from the new world, is spreading over Europe, and will

-continue to nourish an extensive population when the name of the race

-by whom it was first cultivated in South America is forgotten.--_Sir H.

-Davy._

-

-

-THE EARLIEST ENGLISH SCIENTIFIC TREATISE.

-

-Geoffrey Chaucer, the poet, wrote a treatise on the Astrolabe for his

-son, which is the earliest English treatise we have met with on any

-scientific subject. It was not completed; and the apologies which

-Chaucer makes to his own child for writing in English are curious;

-while his inference that his son should therefore “pray God save the

-king that is lord of this language,” is at least as loyal as logical.

-

-

-PHILOSOPHERS’ FALSE ESTIMATES OF THEIR OWN LABOURS.

-

-Galileo was confident that the most important part of his contributions

-to the knowledge of the solar system was his Theory of the Tides--a

-theory which all succeeding astronomers have rejected as utterly

-baseless and untenable. Descartes probably placed far above his

-beautiful explanation of the rainbow, his _à priori_ theory of the

-existence of the vortices which caused the motion of the planets and

-satellites. Newton perhaps considered as one of the best parts of his

-optical researches his explanation of the natural colour of bodies,

-which succeeding optical philosophers have had to reject; and he

-certainly held very strongly the necessity of a material cause for

-gravity, which his disciples have disregarded. Davy looked for his

-greatest triumph in the application of his discoveries to prevent

-the copper bottoms of ships from being corroded. And so in other

-matters.--_Edinburgh Review_, No. 216.

-

-

-RELICS OF GENIUS.

-

-Professor George Wilson, in a lecture to the Scottish Society of

-Arts, says: “The spectacle of these things ministers only to the

-good impulses of humanity. Isaac Newton’s telescope at the Royal

-Society of London; Otto Guericke’s air-pump in the Library at Berlin;

-James Watt’s repaired Newcomen steam-engine in the Natural-Philosophy

-class-room of the College at Glasgow; Fahrenheit’s thermometer in

-the corresponding class-room of the University of Edinburgh; Sir H.

-Davy’s great voltaic battery at the Royal Institution, London, and

-his safety-lamp at the Royal Society; Joseph Black’s pneumatic trough

-in Dr. Gregory’s possession; the first wire which Faraday made rotate

-electro-magnetically, at St. Bartholomew’s Hospital; Dalton’s atomic

-models at Manchester; and Kemp’s liquefied gases in the Industrial

-Museum of Scotland,--are alike personal relics, historical monuments,

-and objects of instruction, which grow more and more precious every

-year, and of which we never can have too many.”

-

-

-THE ROYAL SOCIETY: THE NATURAL AND SUPERNATURAL.

-

-The Royal Society was formed with the avowed object of increasing

-knowledge by direct experiment; and it is worthy of remark, that the

-charter granted by Charles II. to this celebrated institution declares

-that its object is the extension of natural knowledge, as opposed to

-that which is supernatural.

-

-Dr. Paris (_Life of Sir H. Davy_, vol. ii. p. 178) says: “The charter

-of the Royal Society states that it was established for the improvement

-of _natural_ science. This epithet _natural_ was originally intended to

-imply a meaning, of which very few persons, I believe, are aware. At

-the period of the establishment of the society, the arts of witchcraft

-and divination were very extensively encouraged; and the word _natural_

-was therefore introduced in contradistinction to _supernatural_.”

-

-

-THE PHILOSOPHER BOYLE.

-

-After the death of Bacon, one of the most distinguished Englishmen

-was certainly Robert Boyle, who, if compared with his contemporaries,

-may be said to rank immediately below Newton, though of course very

-inferior to him as an original thinker. Boyle was the first who

-instituted exact experiments into the relation between colour and heat;

-and by this means not only ascertained some very important facts, but

-laid a foundation for that union between optics and thermotics, which,

-though not yet completed, now merely waits for some great philosopher

-to strike out a generalisation large enough to cover both, and thus

-fuse the two sciences into a single study. It is also to Boyle, more

-than to any other Englishman, that we owe the science of hydrostatics

-in the state in which we now possess it.[3] He is also the original

-discoverer of that beautiful law, so fertile in valuable results,

-according to which the elasticity of air varies as its density. And,

-in the opinion of one of the most eminent modern naturalists, it was

-Boyle who opened up those chemical inquiries which went on accumulating

-until, a century later, they supplied the means by which Lavoisier and

-his contemporaries fixed the real basis of chemistry, and enabled it

-for the first time to take its proper stand among those sciences that

-deal with the external world.--_Buckle’s History of Civilization_, vol.

-i.

-

-

-SIR ISAAC NEWTON’S ROOMS AND LABORATORY IN TRINITY COLLEGE, CAMBRIDGE.

-

-Of the rooms occupied by Newton during his early residence at

-Cambridge, it is now difficult to settle the locality. The chamber

-allotted to him as Fellow, in 1667, was “the Spiritual Chamber,”

-conjectured to have been the ground-room, next the chapel, but it is

-not certain that he resided there. The rooms in which he lived from

-1682 till he left Cambridge, are in the north-east corner of the great

-court, on the first floor, on the right or north of the gateway or

-principal entrance to the college. His laboratory, as Dr. Humphrey

-Newton tell us, was “on the left end of the garden, near the east end

-of the chapel; and his telescope (refracting) was five feet long, and

-placed at the head of the stairs, going down into the garden.”[4] The

-east side of Newton’s rooms has been altered within the last fifty

-years: Professor Sedgwick, who came up to college in 1804, recollects a

-wooden room, supported on an arcade, shown in Loggan’s view, in place

-of which arcade is now a wooden wall and brick chimney.

-

-  Dr. Humphrey Newton relates that in college Sir Isaac very rarely

-  went to bed till two or three o’clock in the morning, sometimes

-  not till five or six, especially at spring and fall of the leaf,

-  when he used to employ about six weeks in his laboratory, the

-  fire scarcely going out either night or day; he sitting up one

-  night, and Humphrey another, till he had finished his chemical

-  experiments. Dr. Newton describes the laboratory as “well furnished

-  with chymical materials, as bodyes, receivers, heads, crucibles,

-  &c., which was made very little use of, ye crucibles excepted,

-  in which he fused his metals: he would sometimes, though very

-  seldom, look into an old mouldy book, which lay in his laboratory;

-  I think it was titled _Agricola de Metallis_, the transmuting of

-  metals being his chief design, for which purpose antimony was a

-  great ingredient.” “His brick furnaces, _pro re nata_, he made and

-  altered himself without troubling a bricklayer.” “What observations

-  he might make with his telescope, I know not, but several of his

-  observations about comets and the planets may be found scattered

-  here and there in a book intitled _The Elements of Astronomy_, by

-  Dr. David Gregory.”[5]

-

-

-NEWTON’S “APPLE-TREE.”

-

-Curious and manifold as are the trees associated with the great names

-of their planters, or those who have sojourned in their shade, the

-Tree which, by the falling of its fruit, suggested to Newton the idea

-of Gravity, is of paramount interest. It appears that, in the autumn

-of 1665, Newton left his college at Cambridge for his paternal home

-at Woolsthorpe. “When sitting alone in the garden,” says Sir David

-Brewster, “and speculating on the power of gravity, it occurred to him,

-that as the same power by which the apple fell to the ground was not

-sensibly diminished at the greatest distance from the centre of the

-earth to which we can reach, neither at the summits of the loftiest

-spires, nor on the tops of the highest mountains, it might extend to

-the moon and retain her in her orbit, in the same manner as it bends

-into a curve a stone or a cannon-ball when projected in a straight line

-from the surface of the earth.”--_Life of Newton_, vol. i. p. 26. Sir

-David Brewster notes, that neither Pemberton nor Whiston, who received

-from Newton himself his first ideas of gravity, records this story of

-the falling apple. It was mentioned, however, to Voltaire by Catherine

-Barton, Newton’s niece; and to Mr. Green by Martin Folkes, President

-of the Royal Society. Sir David Brewster saw the reputed apple-tree in

-1814, and brought away a portion of one of its roots. The tree was so

-much decayed that it was cut down in 1820, and the wood of it carefully

-preserved by Mr. Turnor, of Stoke Rocheford.

-

-  De Morgan (in _Notes and Queries_, 2d series, No. 139, p. 169)

-  questions whether the fruit was an apple, and maintains that the

-  anecdote rests upon very slight authority; more especially as

-  the idea had for many years been floating before the minds of

-  physical inquirers; although Newton cleared away the confusions and

-  difficulties which prevented very able men from proceeding beyond

-  conjecture, and by this means established _universal_ gravitation.

-

-

-NEWTON’S “PRINCIPIA.”

-

-“It may be justly said,” observes Halley, “that so many and so valuable

-philosophical truths as are herein discovered and put past dispute

-were never yet owing to the capacity and industry of any one man.”

-“The importance and generality of the discoveries,” says Laplace, “and

-the immense number of original and profound views, which have been the

-germ of the most brilliant theories of the philosophers of this (18th)

-century, and all presented with much elegance, will ensure to the work

-on the _Mathematical Principles of Natural Philosophy_ a preëminence

-above all the other productions of human genius.”

-

-

-DESCARTES’ LABOURS IN PHYSICS.

-

-The most profound among the many eminent thinkers France has produced,

-is Réné Descartes, of whom the least that can be said is, that he

-effected a revolution more decisive than has ever been brought about

-by any other single mind; that he was the first who successfully

-applied algebra to geometry; that he pointed out the important law of

-the sines; that in an age in which optical instruments were extremely

-imperfect, he discovered the changes to which light is subjected in

-the eye by the crystalline lens; that he directed attention to the

-consequences resulting from the weight of the atmosphere; and that he

-moreover detected the causes of the rainbow. At the same time, and

-as if to combine the most varied forms of excellence, he is not only

-allowed to be the first geometrician of the age, but by the clearness

-and admirable precision of his style, he became one of the founders

-of French prose. And, although he was constantly engaged in those

-lofty inquiries into the nature of the human mind, which can never

-be studied without wonder, he combined with them a long course of

-laborious experiment upon the animal frame, which raised him to the

-highest rank among the anatomists of his time. The great discovery

-made by Harvey of the Circulation of the Blood was neglected by most

-of his contemporaries; but it was at once recognised by Descartes, who

-made it the basis of the physiological part of his work on man. He was

-likewise the discoverer of the lacteals by Aselli, which, like every

-great truth yet laid before the world, was at its first appearance,

-not only disbelieved, but covered with ridicule.--_Buckle’s History of

-Civilization_, vol. i.

-

-

-CONIC SECTIONS.

-

-If a cone or sugar-loaf be cut through in certain directions, we shall

-obtain figures which are termed conic sections: thus, if we cut through

-a sugar-loaf parallel to its base or bottom, the outline or edge of the

-loaf where it is cut will be _a circle_. If the cut is made so as to

-slant, and not be parallel to the base of the loaf, the outline is an

-_ellipse_, provided the cut goes quite through the sides of the loaf

-all round; but if it goes slanting, and parallel to the line of the

-loaf’s side, the outline is a _parabola_, a conic section or curve,

-which is distinguished by characteristic properties, every point of it

-bearing a certain fixed relation to a certain point within it, as the

-circle does to its centre.--_Dr. Paris’s Notes to Philosophy in Sport,

-&c._

-

-

-POWER OF COMPUTATION.

-

-The higher class of mathematicians, at the end of the seventeenth

-century, had become excellent computers, particularly in England,

-of which Wallis, Newton, Halley, the Gregorys, and De Moivre, are

-splendid examples. Before results of extreme exactness had become

-quite familiar, there was a gratifying sense of power in bringing out

-the new methods. Newton, in one of his letters to Oldenburg, says

-that he was at one time too much attached to such things, and that

-he should be ashamed to say to what number of figures he was in the

-habit of carrying his results. The growth of power of computation on

-the Continent did not, however, keep pace with that of the same in

-England. In 1696, De Laguy, a well-known writer on algebra, and a

-member of the Academy of Sciences, said that the most skilful computer

-could not, in less than a month, find within a unit the cube root of

-696536483318640035073641037.--_De Morgan._

-

-

-“THE SCIENCE OF THE COSMOS.”

-

-Humboldt, characterises this “uncommon but definite expression” as the

-treating of “the assemblage of all things with which space is filled,

-from the remotest nebulæ to the climatic distribution of those delicate

-tissues of vegetable matter which spread a variegated covering over the

-surface of our rocks.” The word _cosmos_, which primitively, in the

-Homeric ages, indicated an idea of order and harmony, was subsequently

-adopted in scientific language, where it was gradually applied to the

-order observed in the movements of the heavenly bodies; to the whole

-universe; and then finally to the world in which this harmony was

-reflected to us.

-

-

-

-

-Physical Phenomena.

-

-

-ALL THE WORLD IN MOTION.

-

-Humboldt, in his _Cosmos_,[6] gives the following beautiful

-illustrative proofs of this phenomenon:

-

-  If, for a moment, we imagine the acuteness of our senses

-  preternaturally heightened to the extreme limits of telescopic

-  vision, and bring together events separated by wide intervals of

-  time, the apparent repose which reigns in space will suddenly

-  vanish; countless stars will be seen moving in groups in various

-  directions; nebulæ wandering, condensing, and dissolving like

-  cosmical clouds; the milky way breaking up in parts, and its

-  veil rent asunder. In every point of the celestial vault we

-  shall recognise the dominion of progressive movement, as on the

-  surface of the earth where vegetation is constantly putting forth

-  its leaves and buds, and unfolding its blossoms. The celebrated

-  Spanish botanist, Cavanilles, first conceived the possibility of

-  “seeing grass grow,” by placing the horizontal micrometer wire

-  of a telescope, with a high magnifying power, at one time on the

-  point of a bamboo shoot, and at another on the rapidly unfolding

-  flowering stem of an American aloe; precisely as the astronomer

-  places the cross of wires on a culminating star. Throughout the

-  whole life of physical nature--in the organic as in the sidereal

-  world--existence, preservation, production, and development, are

-  alike associated with motion as their essential condition.

-

-

-THE AXIS OF ROTATION.

-

-It is remarkable as a mechanical fact, that nothing is so permanent in

-nature as the Axis of Rotation of any thing which is rapidly whirled.

-We have examples of this in every-day practice. The first is the

-motion of _a boy’s hoop_. What keeps the hoop from falling?--It is its

-rotation, which is one of the most complicated subjects in mechanics.

-

-Another thing pertinent to this question is, _the motion of a quoit_.

-Every body who ever threw a quoit knows that to make it preserve its

-position as it goes through the air, it is necessary to give it a

-whirling motion. It will be seen that while whirling, it preserves its

-plane, whatever the position of the plane may be, and however it may

-be inclined to the direction in which the quoit travels. Now, this has

-greater analogy with the motion of the earth than any thing else.

-

-Another illustration is _the motion of a spinning top_. The greatest

-mathematician of the last century, the celebrated Euler, has written

-a whole book on the motion of a top, and his Latin treatise _De motu

-Turbinis_ is one of the most remarkable books on mechanics. The motion

-of a top is a matter of the greatest importance; it is applicable

-to the elucidation of some of the greatest phenomena of nature. In

-all these instances there is this wonderful tendency in rotation to

-preserve the axis of rotation unaltered.--_Prof. Airy’s Lect. on

-Astronomy._

-

-

-THE EARTH’S ANNUAL MOTION.

-

-In conformity with the Copernican view of our system, we must learn to

-look upon the sun as the comparatively motionless centre about which

-the earth performs an annual elliptic orbit of the dimensions and

-excentricity, and with a velocity, regulated according to a certain

-assigned law; the sun occupying one of the foci of the ellipse, and

-from that station quietly disseminating on all sides its light and

-heat; while the earth travelling round it, and presenting itself

-differently to it at different times of the year and day, passes

-through the varieties of day and night, summer and winter, which we

-enjoy.--_Sir John Herschel’s Outlines of Astronomy._

-

-Laplace has shown that the length of the day has not varied the

-hundredth part of a second since the observations of Hipparchus, 2000

-years ago.

-

-

-STABILITY OF THE OCEAN.

-

-In submitting this question to analysis, Laplace found that the

-_equilibrium of the ocean is stable if its density is less than

-the mean density of the earth_, and that its equilibrium cannot be

-subverted unless these two densities are equal, or that of the earth

-less than that of its waters. The experiments on the attraction of

-Schehallien and Mont Cenis, and those made by Cavendish, Reich, and

-Baily, with balls of lead, demonstrate that the mean density of the

-earth is at least _five_ times that of water, and hence the stability

-of the ocean is placed beyond a doubt. As the seas, therefore, have at

-one time covered continents which are now raised above their level,

-we must seek for some other cause of it than any want of stability in

-the equilibrium of the ocean. How beautifully does this conclusion

-illustrate the language of Scripture, “Hitherto shalt thou come, but no

-further”! (_Job_ xxxviii. 11.)

-

-

-COMPRESSION OF BODIES.

-

-Sir John Leslie observes, that _air compressed_ into the fiftieth

-part of its volume has its elasticity fifty times augmented: if it

-continued to contract at that rate, it would, from its own incumbent

-weight, acquire the density of water at the depth of thirty-four

-miles. But water itself would have its density doubled at the depth

-of ninety-three miles, and would attain the density of quicksilver at

-the depth of 362 miles. In descending, therefore, towards the centre,

-through nearly 4000 miles, the condensation of ordinary substances

-would surpass the utmost powers of conception. Dr. Young says, that

-steel would be compressed into one-fourth, and stone into one-eighth,

-of its bulk at the earth’s centre.--_Mrs. Somerville._

-

-

-THE WORLD IN A NUTSHELL.

-

-From the many proofs of the non-contact of the atoms, even in the

-most solid parts of bodies; from the very great space obviously

-occupied by pores--the mass having often no more solidity than a heap

-of empty boxes, of which the apparently solid parts may still be as

-porous in a second degree and so on; and from the great readiness

-with which light passes in all directions through dense bodies, like

-glass, rock-crystal, diamond, &c., it has been argued that there is so

-exceedingly little of really solid matter even in the densest mass,

-that _the whole world_, if the atoms could be brought into absolute

-contact, _might be compressed into a nutshell_. We have as yet no means

-of determining exactly what relation this idea has to truth.--_Arnott._

-

-

-THE WORLD OF ATOMS.

-

-The infinite groups of atoms flying through all time and space, in

-different directions and under different laws, have interchangeably

-tried and exhibited every possible mode of rencounter: sometimes

-repelled from each other by concussion; and sometimes adhering to each

-other from their own jagged or pointed construction, or from the casual

-interstices which two or more connected atoms must produce, and which

-may be just adapted to those of other figures,--as globular, oval, or

-square. Hence the origin of compound and visible bodies; hence the

-origin of large masses of matter; hence, eventually, the origin of the

-world.--_Dr. Good’s Book of Nature._

-

-The great Epicurus speculated on “the plastic nature” of atoms, and

-attributed to this _nature_ the power they possess of arranging

-themselves into symmetric forms. Modern philosophers satisfy themselves

-with attraction; and reasoning from analogy, imagine that each atom has

-a polar system.--_Hunt’s Poetry of Science._

-

-

-MINUTE ATOMS OF THE ELEMENTS: DIVISIBILITY OF MATTER.

-

-So minute are the parts of the elementary bodies in their ultimate

-state of division, in which condition they are usually termed _atoms_,

-as to elude all our powers of inspection, even when aided by the most

-powerful microscopes. Who can see the particles of gold in a solution

-of that metal in _aqua regia_, or those of common salt when dissolved

-in water? Dr. Thomas Thomson has estimated the bulk of an ultimate

-particle or atom of lead as less than 1/888492000000000th of a cubic

-inch, and concludes that its weight cannot exceed the 1/310000000000th

-of a grain.

-

-This curious calculation was made by Dr. Thomson, in order to show to

-what degree Matter could be divided, and still be sensible to the eye.

-He dissolved a grain of nitrate of lead in 500,000 grains of water,

-and passed through the solution a current of sulphuretted hydrogen;

-when the whole liquid became sensibly discoloured. Now, a grain of

-water may be regarded as being almost equal to a drop of that liquid,

-and a drop may be easily spread out so as to cover a square inch of

-surface. But under an ordinary microscope the millionth of a square

-inch may be distinguished by the eye. The water, therefore, could be

-divided into 500,000,000,000 parts. But the lead in a grain of nitrate

-of lead weighs 0·62 of a grain; an atom of lead, accordingly, cannot

-weigh more than 1/810000000000th of a grain; while the atom of sulphur,

-which in combination with the lead rendered it visible, could not

-weigh more than 1/2015000000000, that is, the two-billionth part of a

-grain.--_Professor Low_; _Jameson’s Journal_, No. 106.

-

-

-WEIGHT OF AIR.

-

-Air can be so rarefied that the contents of a cubic foot shall not

-weigh the tenth part of a grain: if a quantity that would fill a space

-the hundredth part of an inch in diameter be separated from the rest,

-the air will still be found there, and we may reasonably conceive that

-there may be several particles present, though the weight is less than

-the seventeen-hundred-millionth of a grain.

-

-

-DURATION OF THE PYRAMID.

-

-The great reason of the duration of the pyramid above all other forms

-is, that it is most fitted to resist the force of gravitation. Thus the

-Pyramids of Egypt are the oldest monuments in the world.

-

-

-INERTIA ILLUSTRATED.

-

-Many things of common occurrence (says Professor Tyndall) are to be

-explained by reference to the quality of inactivity. We will here state

-a few of them.

-

-When a railway train is moving, if it strike against any obstacle which

-arrests its motion, the passengers are thrown forward in the direction

-in which the train was proceeding. Such accidents often occur on a

-small scale, in attaching carriages at railway stations. The reason is,

-that the passengers share the motion of the train, and, as matter, they

-tend to persist in motion. When the train is suddenly checked, this

-tendency exhibits itself by the falling forward referred to. In like

-manner, when a train previously at rest is suddenly set in motion, the

-tendency of the passengers to remain at rest evinces itself by their

-falling in a direction opposed to that in which the train moves.

-

-

-THE LEANING TOWER OF PISA.[7]

-

-Sir John Leslie used to attribute the stability of this tower to

-the cohesion of the mortar it is built with being sufficient to

-maintain it erect, in spite of its being out of the condition required

-by physics--to wit, that “in order that a column shall stand, a

-perpendicular let fall from the centre of gravity must fall within the

-base.” Sir John describes the Tower of Pisa to be in violation of this

-principle; but, according to later authorities, the perpendicular falls

-within the base.

-

-

-EARLY PRESENTIMENTS OF CENTRIFUGAL FORCES.

-

-Jacobi, in his researches on the mathematical knowledge of the

-Greeks, comments on “the profound consideration of nature evinced by

-Anaxagoras, in whom we read with astonishment a passage asserting that

-the moon, if the centrifugal force were intermitted, would fall to the

-earth like a stone from a sling.” Anaxagoras likewise applied the same

-theory of “falling where the force of rotation had been intermitted”

-to all the material celestial bodies. In Aristotle and Simplicius may

-also be traced the idea of “the non-falling of heavenly bodies when the

-rotatory force predominates over the actual falling force, or downward

-attraction;” and Simplicius mentions that “water in a phial is not

-spilt when the movement of rotation is more rapid than the downward

-movement of the water.” This is illustrated at the present day by

-rapidly whirling a pail half-filled with water without spilling a drop.

-

-Plato had a clearer idea than Aristotle of the _attractive force_

-exercised by the earth’s centre on all heavy bodies removed from

-it; for he was acquainted with the acceleration of falling bodies,

-although he did not correctly understand the cause. John Philoponus,

-the Alexandrian, probably in the sixth century, was the first who

-ascribed the movement of the heavenly bodies to a primitive impulse,

-connecting with this idea that of the fall of bodies, or the tendency

-of all substances, whether heavy or light, to reach the ground. The

-idea conceived by Copernicus, and more clearly expressed by Kepler,

-who even applied it to the ebb and flow of the ocean, received in 1666

-and 1674 a new impulse from Robert Hooke; and next Newton’s theory

-of gravitation presented the grand means of converting the whole of

-physical astronomy into a true _mechanism of the heavens_.

-

-The law of gravitation knows no exception; it accounts accurately for

-the most complex motions of the members of our own system; nay more,

-the paths of double stars, far removed from all appreciable effects

-of our portion of the universe, are in perfect accordance with its

-theory.[8]

-

-

-HEIGHT OF FALLS.

-

-The fancy of the Greeks delighted itself in wild visions of the height

-of falls. In Hesiod’s _Theogony_ it is said, speaking of the fall

-of the Titans into Tartarus, “if a brazen anvil were to fall from

-heaven nine days and nine nights long, it would reach the earth on the

-tenth.” This descent of the anvil in 777,600 seconds of time gives an

-equivalent in distance of 309,424 geographical miles (allowance being

-made, according to Galle’s calculation, for the considerable diminution

-in force of attraction at planetary distances); therefore 1½ times the

-distance of the moon from the earth. But, according to the _Iliad_,

-Hephæstus fell down to Lemnos in one day; “when but a little breath was

-still in him.”--_Note to Humboldt’s Cosmos_, vol. iii.

-

-

-RATE OF THE FALL OF BODIES.

-

-A body falls in gravity precisely 16-1/16 feet in a second, and the

-velocity increases according to the squares of the time, viz.:

-

-    In ¼ (quarter of a second) a body falls           1 foot.

-       ½ (half a second)                              4 feet.

-       1 second                                      16  ”

-       2 ditto                                       64  ”

-       3 ditto                                      144  ”

-

-The power of gravity at two miles distance from the earth is four times

-less than at one mile; at three miles nine times less, and so on. It

-goes on lessening, but is never destroyed.--_Notes in various Sciences._

-

-

-VARIETIES OF SPEED.

-

-A French scientific work states the ordinary rate to be:

-

-                                                    per second.

-    Of a man walking                                   4 feet.

-    Of a good horse in harness                        12  ”

-    Of a rein-deer in a sledge on the ice             26  ”

-    Of an English race-horse                          43  ”

-    Of a hare                                         88  ”

-    Of a good sailing ship                            19  ”

-    Of the wind                                       82  ”

-    Of sound                                        1038  ”

-    Of a 24-pounder cannon-ball                     1300  ”

-

-

-LIFTING HEAVY PERSONS.

-

-One of the most extraordinary pages in Sir David Brewster’s _Letters

-on Natural Magic_ is the experiment in which a heavy man is raised

-with the greatest facility when he is lifted up the instant that his

-own lungs, and those of the persons who raise him, are inflated with

-air. Thus the heaviest person in the party lies down upon two chairs,

-his legs being supported by the one and his back by the other. Four

-persons, one at each leg, and one at each shoulder, then try to raise

-him--the person to be raised giving two signals, by clapping his hands.

-At the first signal, he himself and the four lifters begin to draw a

-long and full breath; and when the inhalation is completed, or the

-lungs filled, the second signal is given for raising the person from

-the chair. To his own surprise, and that of his bearers, he rises with

-the greatest facility, as if he were no heavier than a feather. Sir

-David Brewster states that he has seen this inexplicable experiment

-performed more than once; and he appealed for testimony to Sir Walter

-Scott, who had repeatedly seen the experiment, and performed the part

-both of the load and of the bearer. It was first shown in England by

-Major H., who saw it performed in a large party at Venice, under the

-direction of an officer of the American navy.[9]

-

-Sir David Brewster (in a letter to _Notes and Queries_, No. 143)

-further remarks, that “the inhalation of the lifters the moment the

-effort is made is doubtless essential, and for this reason: when we

-make a great effort, either in pulling or lifting, we always fill the

-chest with air previous to the effort; and when the inhalation is

-completed, we close the _rima glottidis_ to keep the air in the lungs.

-The chest being thus kept expanded, the pulling or lifting muscles have

-received as it were a fulcrum round which their power is exerted; and

-we can thus lift the greatest weight which the muscles are capable of

-doing. When the chest collapses by the escape of the air, the lifters

-lose their muscular power; reinhalation of air by the liftee can

-certainly add nothing to the power of the lifters, or diminish his

-own weight, which is only increased by the weight of the air which he

-inhales.”

-

-

-“FORCE CAN NEITHER BE CREATED NOR DESTROYED.”

-

-Professor Faraday, in his able inquiry upon “the Conservation of

-Force,” maintains that to admit that force may be destructible, or can

-altogether disappear, would be to admit that matter could be uncreated;

-for we know matter only by its forces. From his many illustrations we

-select the following:

-

-  The indestructibility of individual matter is a most important case

-  of the Conservation of Chemical Force. A molecule has been endowed

-  with powers which give rise in it to various qualities; and those

-  never change, either in their nature or amount. A particle of

-  oxygen is ever a particle of oxygen; nothing can in the least wear

-  it. If it enters into combination, and disappears as oxygen; if it

-  pass through a thousand combinations--animal, vegetable, mineral;

-  if it lie hid for a thousand years, and then be evolved,--it is

-  oxygen with the first qualities, neither more nor less. It has

-  all its original force, and only that; the amount of force which

-  it disengaged when hiding itself, has again to be employed in a

-  reverse direction when it is set at liberty: and if, hereafter,

-  we should decompose oxygen, and find it compounded of other

-  particles, we should only increase the strength of the proof of the

-  conservation of force; for we should have a right to say of these

-  particles, long as they have been hidden, all that we could say of

-  the oxygen itself.

-

-In conclusion, he adds:

-

-  Let us not admit the destruction or creation of force without clear

-  and constant proof. Just as the chemist owes all the perfection

-  of his science to his dependence on the certainty of gravitation

-  applied by the balance, so may the physical philosopher expect to

-  find the greatest security and the utmost aid in the principle

-  of the conservation of force. All that we have that is good and

-  safe--as the steam-engine, the electric telegraph, &c.--witness to

-  that principle; it would require a perpetual motion, a fire without

-  heat, heat without a source, action without reaction, cause without

-  effect, or effect without cause, to displace it from its rank as a

-  law of nature.

-

-

-NOTHING LOST IN THE MATERIAL WORLD.

-

-“It is remarkable,” says Kobell in his _Mineral Kingdom_, “how a change

-of place, a circulation as it were, is appointed for the inanimate or

-naturally immovable things upon the earth; and how new conditions,

-new creations, are continually developing themselves in this way. I

-will not enter here into the evaporation of water, for instance from

-the widely-spreading ocean; how the clouds produced by this pass over

-into foreign lands and then fall again to the earth as rain, and how

-this wandering water is, partly at least, carried along new journeys,

-returning after various voyages to its original home: the mere

-mechanical phenomena, such as the transfer of seeds by the winds or by

-birds, or the decomposition of the surface of the earth by the friction

-of the elements, suffice to illustrate this.”

-

-

-TIME AN ELEMENT OF FORCE.

-

-Professor Faraday observes that Time is growing up daily into

-importance as an element in the exercise of Force, which he thus

-strikingly illustrates:

-

-  The earth moves in its orbit of time; the crust of the earth moves

-  in time; light moves in time; an electro-magnet requires time for

-  its charge by an electric current: to inquire, therefore, whether

-  power, acting either at sensible or insensible distances, always

-  acts in _time_, is not to be metaphysical; if it acts in time and

-  across space, it must act by physical lines of force; and our view

-  of the nature of force may be affected to the extremest degree

-  by the conclusions which experiment and observation on time may

-  supply, being perhaps finally determinable only by them. To inquire

-  after the possible time in which gravitating, magnetic, or electric

-  force is exerted, is no more metaphysical than to mark the times

-  of the hands of a clock in their progress; or that of the temple

-  of Serapis, and its ascents and descents; or the periods of the

-  occultation of Jupiter’s satellites; or that in which the light

-  comes from them to the earth. Again, in some of the known cases of

-  the action of time something happens while _the time_ is passing

-  which did not happen before, and does not continue after; it is

-  therefore not metaphysical to expect an effect in _every_ case, or

-  to endeavour to discover its existence and determine its nature.

-

-

-CALCULATION OF HEIGHTS AND DISTANCES.

-

-By the assistance of a seconds watch the following interesting

-calculations may be made:

-

-  If a traveller, when on a precipice or on the top of a building,

-  wish to ascertain the height, he should drop a stone, or any other

-  substance sufficiently heavy not to be impeded by the resistance of

-  the atmosphere; and the number of seconds which elapse before it

-  reaches the bottom, carefully noted on a seconds watch, will give

-  the height. For the stone will fall through the space of 16-1/8

-  feet during the first second, and will increase in rapidity as the

-  square of the time employed in the fall: if, therefore, 16-1/8 be

-  multiplied by the number of seconds the stone has taken to fall,

-  this product also multiplied by the same number of seconds will

-  give the height. Suppose the stone takes five seconds to reach the

-  bottom:

-

-    16-1/8 × 5 = 80-5/8 × 5 = 403-1/8, height of the precipice.

-

-  The Count Xavier de Maistre, in his _Expédition nocturne autour

-  de ma Chambre_, anxious to ascertain the exact height of his room

-  from the ground on which Turin is built, tells us he proceeded

-  as follows: “My heart beat quickly, and I just counted three

-  pulsations from the instant I dropped my slipper until I heard

-  the sound as it fell in the street, which, according to the

-  calculations made of the time taken by bodies in their accelerated

-  fall, and of that employed by the sonorous undulations of the

-  air to arrive from the street to my ear, gave the height of my

-  apartment as 94 feet 3 inches 1 tenth (French measure), supposing

-  that my heart, agitated as it was, beat 120 times in a minute.”

-

-  A person travelling may ascertain his rate of walking by the aid

-  of a slight string with a piece of lead at one end, and the use of

-  a seconds watch; the string being knotted at distances of 44 feet,

-  the 120th part of an English mile, and bearing the same proportion

-  to a mile that half a minute bears to an hour. If the traveller,

-  when going at his usual rate, drops the lead, and suffers the

-  string to slip through his hand, the number of knots which pass in

-  half a minute indicate the number of miles he walks in an hour.

-  This contrivance is similar to a _log-line_ for ascertaining a

-  ship’s rate at sea: the lead is enclosed in wood (whence the name

-  _log_), that it may float, and the divisions, which are called

-  _knots_, are measured for nautical miles. Thus, if ten knots are

-  passed in half a minute, they show that the vessel is sailing at

-  the rate of ten knots, or miles, an hour: a seconds watch would

-  here be of great service, but the half-minute sand-glass is in

-  general use.

-

-  The rapidity of a river may be ascertained by throwing in a light

-  floating substance, which, if not agitated by the wind, will move

-  with the same celerity as the water: the distance it floats in a

-  certain number of seconds will give the rapidity of the stream; and

-  this indicates the height of its source, the nature of its bottom,

-  &c.--See _Sir Howard Douglas on Bridges_. _Thomson’s Time and

-  Time-keepers._

-

-

-SAND IN THE HOUR-GLASS.

-

-It is a noteworthy fact, that the flow of Sand in the Hour-glass is

-perfectly equable, whatever may be the quantity in the glass; that is,

-the sand runs no faster when the upper half of the glass is quite full

-than when it is nearly empty. It would, however, be natural enough to

-conclude, that when full of sand it would be more swiftly urged through

-the aperture than when the glass was only a quarter full, and near the

-close of the hour.

-

-The fact of the even flow of sand may be proved by a very simple

-experiment. Provide some silver sand, dry it over or before the fire,

-and pass it through a tolerably fine sieve. Then take a tube, of any

-length or diameter, closed at one end, in which make a small hole, say

-the eighth of an inch; stop this with a peg, and fill up the tube with

-the sifted sand. Hold the tube steadily, or fix it to a wall or frame

-at any height from a table; remove the peg, and permit the sand to flow

-in any measure for any given time, and note the quantity. Then let the

-tube be emptied, and only half or a quarter filled with sand; measure

-again for a like time, and the same quantity of sand will flow: even if

-you press the sand in the tube with a ruler or stick, the flow of the

-sand through the hole will not be increased.

-

-The above is explained by the fact, that when the sand is poured into

-the tube, it fills it with a succession of conical heaps; and that all

-the weight which the bottom of the tube sustains is only that of the

-heap which _first_ falls upon it, as the succeeding heaps do not press

-downward, but only against the sides or walls of the tube.

-

-

-FIGURE OF THE EARTH.

-

-By means of a purely astronomical determination, based upon the action

-which the earth exerts on the motion of the moon, or, in other words,

-on the inequalities in lunar longitudes and latitudes, Laplace has

-shown in one single result the mean Figure of the Earth.

-

-  It is very remarkable that an astronomer, without leaving his

-  observatory, may, merely by comparing his observations with

-  mean analytical results, not only be enabled to determine with

-  exactness the size and degree of ellipticity of the earth, but

-  also its distance from the sun and moon; results that otherwise

-  could only be arrived at by long and arduous expeditions to the

-  most remote parts of both hemispheres. The moon may therefore, by

-  the observation of its movements, render appreciable to the higher

-  departments of astronomy the ellipticity of the earth, as it taught

-  the early astronomers the rotundity of our earth by means of its

-  eclipses.--_Laplace’s Expos. du Syst. du Monde._

-

-

-HOW TO ASCERTAIN THE EARTH’S MAGNITUDE.

-

-Sir John Herschel gives the following means of approximation. It

-appears by observation that two points, each ten feet above the

-surface, cease to be visible from each other over still water, and, in

-average atmospheric circumstances, at a distance of about eight miles.

-But 10 feet is the 528th part of a mile; so that half their distance,

-or four miles, is to the height of each as 4 × 528, or 2112:1, and

-therefore in the same proportion to four miles is the length of the

-earth’s diameter. It must, therefore, be equal to 4 × 2112 = 8448, or

-in round numbers, about 8000 miles, which is not very far from the

-truth.

-

-  The excess is, however, about 100 miles, or 1/80th part. As

-  convenient numbers to remember, the reader may bear in mind, that

-  in our latitude there are just as many thousands of feet in a

-  degree of the meridian as there are days in the year (365); that,

-  speaking loosely, a degree is about seventy British statute miles,

-  and a second about 100 feet; that the equatorial circumference of

-  the earth is a little less than 25,000 miles (24,899), and the

-  ellipticity or polar flattening amounts to 1/300th part of the

-  diameter.--_Outlines of Astronomy._

-

-

-MASS AND DENSITY OF THE EARTH.

-

-With regard to the determination of the Mass and Density of the Earth

-by direct experiment, we have, in addition to the deviations of the

-pendulum produced by mountain masses, the variation of the same

-instruments when placed in a mine 1200 feet in depth. The most recent

-experiments were conducted by Professor Airy, in the Harton coal-pit,

-near South Shields:[10] the oscillations of the pendulum at the bottom

-of the pit were compared with those of a clock above; the beats of the

-clock were transferred below for comparison by an electrio wire; and it

-was thus determined that a pendulum vibrating seconds at the mouth of

-the pit would gain 2¼ seconds per day at its bottom. The final result

-of the calculations depending on this experiment, which were published

-in the _Philosophical Transactions_ of 1856, gives 6·565 for the mean

-density of the earth. The celebrated Cavendish experiment, by means

-of which the density of the earth was determined by observing the

-attraction of leaden balls on each other, has been repeated in a manner

-exhibiting an astonishing amount of skill and patience by the late Mr.

-F. Baily.[11] The result of these experiments, combined with those

-previously made, gives as a mean result 5·441 as the earth’s density,

-when compared with water; thus confirming one of Newton’s astonishing

-divinations, that the mean density of the earth would be found to be

-between five and six times that of water.

-

-  Humboldt is, however, of opinion that “we know only the mass of

-  the whole earth and its mean density by comparing it with the

-  open strata, which alone are accessible to us. In the interior of

-  the earth, where all knowledge of its chemical and mineralogical

-  character fails, we are limited to as pure conjecture as in the

-  remotest bodies that revolve round the sun. We can determine

-  nothing with certainty regarding the depth at which the geological

-  strata must be supposed to be in a state of softening or of liquid

-  fusion, of the condition of fluids when heated under an enormous

-  pressure, or of the law of the increase of density from the upper

-  surface to the centre of the earth.”--_Cosmos_, vol. i.

-

-In M. Foucault’s beautiful experiment, by means of the vibration of

-a long pendulum, consisting of a heavy mass of metal suspended by a

-long wire from a strong fixed support, is demonstrated to the eye

-the rotation of the earth. The Gyroscope of the same philosopher

-is regarded not as a mere philosophical toy; but the principles of

-dynamics, by means of which it is made to demonstrate the earth’s

-rotation on its own axis, are explained with the greatest clearness.

-Thus the ingenuity of M. Foucault, combined with a profound knowledge

-of mechanics, has obtained proofs of one of the most interesting

-problems of astronomy from an unsuspected source.

-

-

-THE EARTH AND MAN COMPARED.

-

-The Earth--speaking roundly--is 8000 miles in diameter; the atmosphere

-is calculated to be fifty miles in altitude; the loftiest mountain peak

-is estimated at five miles above the level of the sea, for this height

-has never been visited by man; the deepest mine that he has formed is

-1650 feet; and his own stature does not average six feet. Therefore, if

-it were possible for him to construct a globe 800 feet--or twice the

-height of St. Paul’s Cathedral--in diameter, and to place upon any one

-point of its surface an atom of 1/4380th of an inch in diameter, and

-1/720th of an inch in height, it would correctly denote the proportion

-that man bears to the earth upon which he moves.

-

-  When by measurements, in which the evidence of the method advances

-  equally with the precision of the results, the volume of the earth

-  is reduced to the millionth part of the volume of the sun; when

-  the sun himself, transported to the region of the stars, takes

-  up a very modest place among the thousands of millions of those

-  bodies that the telescope has revealed to us; when the 38,000,000

-  of leagues which separate the earth from the sun have become, by

-  reason of their comparative smallness, a base totally insufficient

-  for ascertaining the dimensions of the visible universe; when even

-  the swiftness of the luminous rays (77,000 leagues per second)

-  barely suffices for the common valuations of science; when, in

-  short, by a chain of irresistible proofs, certain stars have

-  retired to distances that light could not traverse in less than a

-  million of years;--we feel as if annihilated by such immensities.

-  In assigning to man and to the planet that he inhabits so small a

-  position in the material world, astronomy seems really to have made

-  progress only to humble us.--_Arago._

-

-

-MEAN TEMPERATURE OF THE EARTH’S SURFACE.

-

-Professor Dove has shown, by taking at all seasons the mean of the

-temperature of points diametrically opposite to each other, that the

-mean temperature _of the whole earth’s surface_ in June considerably

-exceeds that in December. This result, which is at variance with the

-greater proximity of the sun in December, is, however, due to a totally

-different and very powerful cause,--the greater amount of land in

-that hemisphere which has its summer solstice in June (_i. e._ the

-northern); and the fact is so explained by him. The effect of land

-under sunshine is to throw heat into the general atmosphere, and to

-distribute it by the carrying power of the latter over the whole earth.

-Water is much less effective in this respect, the heat penetrating its

-depths and being there absorbed; so that the surface never acquires

-a very elevated temperature, even under the equator.--_Sir John

-Herschel’s Outlines._

-

-

-TEMPERATURE OF THE EARTH STATIONARY.

-

-Although, according to Bessel, 25,000 cubic miles of water flow in

-every six hours from one quarter of the earth to another, and the

-temperature is augmented by the ebb and flow of every tide, all

-that we know with certainty is, that the _resultant effect_ of all

-the thermal agencies to which the earth is exposed has undergone

-no perceptible change within the historic period. We owe this fine

-deduction to Arago. In order that the _date palm_ should ripen its

-fruit, the mean temperature of the place must exceed 70 deg. Fahr.;

-and, on the other hand, the _vine_ cannot be cultivated successfully

-when the temperature is 72 deg. or upwards. Hence the mean temperature

-of any place at which these two plants flourished and bore fruit must

-lie between these narrow limits, _i. e._ could not differ from 71 deg.

-Fahr. by more than a single degree. Now from the Bible we learn that

-both plants were _simultaneously_ cultivated in the central valleys

-of Palestine in the time of Moses; and its then temperature is thus

-definitively determined. It is the same at the present time; so that

-the mean temperature of this portion of the globe has not sensibly

-altered in the course of thirty-three centuries.

-

-

-THEORY OF CRYSTALLISATION.

-

-Professor Plücker has ascertained that certain crystals, in particular

-the cyanite, “point very well to the north by the magnetic power of the

-earth only. It is a true compass-needle; and more than that, you may

-obtain its declination.” Upon this Mr. Hunt remarks: “We must remember

-that this crystal, the cyanite, is a compound of silica and alumina

-only. This is the amount of experimental evidence which science has

-afforded in explanation of the conditions under which nature pursues

-her wondrous work of crystal formation. We see just sufficient of

-the operation to be convinced that the luminous star which shines in

-the brightness of heaven, and the cavern-secreted gem, are equally

-the result of forces which are known to us in only a few of their

-modifications.”--_Poetry of Science._

-

-Gay Lussac first made the remark, that a crystal of potash-alum,

-transferred to a solution of ammonia-alum, continued to increase

-without its form being modified, and might thus be covered with

-alternate layers of the two alums, preserving its regularity and proper

-crystalline figure. M. Beudant afterwards observed that other bodies,

-such as the sulphates of iron and copper, might present themselves

-in crystals of the same form and angles, although the form was not a

-simple one, like that of alum. But M. Mitscherlich first recognised

-this correspondence in a sufficient number of cases to prove that it

-was a general consequence of similarity of composition in different

-bodies.--_Graham’s Elements of Chemistry._

-

-

-IMMENSE CRYSTALS.

-

-Crystals are found in the most microscopic character, and of an

-exceedingly large size. A crystal of quartz at Milan is three feet and

-a quarter long, and five feet and a half in circumference: its weight

-is 870 pounds. Beryls have been found in New Hampshire measuring four

-feet in length.--_Dana._

-

-

-VISIBLE CRYSTALLISATION.

-

-Professor Tyndall, in a lecture delivered by him at the Royal

-Institution, London, on the properties of Ice, gave the following

-interesting illustration of crystalline force. By perfectly cleaning a

-piece of glass, and placing on it a film of a solution of chloride of

-ammonium or sal ammoniac, the action of crystallisation was shown to

-the whole audience. The glass slide was placed in a microscope, and the

-electric light passing through it was concentrated on a white disc. The

-image of the crystals, as they started into existence, and shot across

-the disc in exquisite arborescent and symmetrical forms, excited the

-admiration of every one. The lecturer explained that the heat, causing

-the film of moisture to evaporate, brought the particles of salt

-sufficiently near to exercise the crystalline force, the result being

-the beautiful structure built up with such marvellous rapidity.

-

-

-UNION OF MINERALOGY AND GEOMETRY.

-

-It is a peculiar characteristic of minerals, that while plants and

-animals differ in various regions of the earth, mineral matter of the

-same character may be discovered in any part of the world,--at the

-Equator or towards the Poles; at the summit of the loftiest mountains,

-and in works far beneath the level of the sea. The granite of Australia

-does not necessarily differ from that of the British islands; and ores

-of the same metals (the proper geological conditions prevailing) may

-be found of the same general character in all regions. Climate and

-geographical position have no influence on the composition of mineral

-substances.

-

-This uniformity may, in some measure, have induced philosophers to

-seek its extension to the forms of crystallography. About 1760 (says

-Mr. Buckle, in his _History of Civilization_), Romé de Lisle set the

-first example of studying crystals, according to a scheme so large as

-to include all the varieties of their primary forms, and to account

-for their irregularities and the apparent caprice with which they

-were arranged. In this investigation he was guided by the fundamental

-assumption, that what is called an irregularity is in truth perfectly

-regular, and that the operations of nature are invariable. Haüy applied

-this great idea to the almost innumerable forms in which minerals

-crystallise. He thus achieved a complete union between mineralogy and

-geometry; and, bringing the laws of space to bear on the molecular

-arrangements of matter, he was able to penetrate into the intimate

-structure of crystals. By this means he proved that the secondary

-forms of all crystals are derived from their primary forms by a

-regular process of decrement; and that when a substance is passing

-from a liquid to a solid state, its particles cohere, according to a

-scheme which provides for every possible change, since it includes

-even those subsequent layers which alter the ordinary type of the

-crystal, by disturbing its natural symmetry. To ascertain that such

-violations of symmetry are susceptible of mathematical calculation,

-was to make a vast addition to our knowledge; and, by proving that

-even the most uncouth and singular forms are the natural results of

-their antecedents, Haüy laid the foundation of what may be called the

-pathology of the inorganic world. However paradoxical such a notion may

-appear, it is certain that symmetry is to crystals what health is to

-animals; so that an irregularity of shape in the first corresponds with

-an appearance of disease in the second.--See _Hist. Civilization_, vol.

-i.

-

-

-REPRODUCTIVE CRYSTALLISATION.

-

-The general belief that only organic beings have the power of

-reproducing lost parts has been disproved by the experiments of Jordan

-on crystals. An octohedral crystal of alum was fractured; it was then

-replaced in a solution, and after a few days its injury was seen to be

-repaired. The whole crystal had of course increased in size; but the

-increase on the broken surface had been so much greater that a perfect

-octohedral form was regained.--_G. H. Lewes._

-

-This remarkable power possessed by crystals, in common with animals,

-of repairing their own injuries had, however, been thus previously

-referred to by Paget, in his _Pathology_, confirming the experiments

-of Jordan on this curious subject: “The ability to repair the damages

-sustained by injury ... is not an exclusive property of living beings;

-for even crystals will repair themselves when, after pieces have been

-broken from them, they are placed in the same conditions in which they

-were first formed.”

-

-

-GLASS BROKEN BY SAND.

-

-In some glass-houses the workmen show glass which has been cooled in

-the open air; on this they let fall leaden bullets without breaking the

-glass. They afterwards desire you to let a few grains of sand fall upon

-the glass, by which it is broken into a thousand pieces. The reason

-of this is, that the lead does not scratch the surface of the glass;

-whereas the sand, being sharp and angular, scratches it sufficiently to

-produce the above effect.

-

-

-

-

-Sound and Light.

-

-

-SOUNDING SAND.

-

-Mr. Hugh Miller, the geologist, when in the island of Eigg, in the

-Hebrides, observed that a musical sound was produced when he walked

-over the white dry sand of the beach. At each step the sand was driven

-from his footprint, and the noise was simultaneous with the scattering

-of the sand; the cause being either the accumulated vibrations of

-the air when struck by the driven sand, or the accumulated sounds

-occasioned by the mutual impact of the particles of sand against each

-other. If a musket-ball passing through the air emits a whistling note,

-each individual particle of sand must do the same, however faint be

-the note which it yields; and the accumulation of these infinitesimal

-vibrations must constitute an audible sound, varying with the number

-and velocity of the moving particles. In like manner, if two plates of

-silex or quartz, which are but crystals of sand, give out a musical

-sound when mutually struck, the impact or collision of two minute

-crystals or particles of sand must do the same, in however inferior a

-degree; and the union of all these sounds, though singly imperceptible,

-may constitute the musical notes of “the Mountain of the Bell” in

-Arabia Petræa, or the lesser sounds of the trodden sea-beach of

-Eigg.--_North-British Review_, No. 5.

-

-

-INTENSITY OF SOUND IN RAREFIED AIR.

-

-The experiences during ascents of the highest mountains are

-contradictory. Saussure describes the sounds on the top of Mont Blanc

-as remarkably weak: a pistol-shot made no more noise than an ordinary

-Chinese cracker, and the popping of a bottle of champagne was scarcely

-audible. Yet Martius, in the same situation, was able to distinguish

-the voices of the guides at a distance of 1340 feet, and to hear the

-tapping of a lead pencil upon a metallic surface at a distance of from

-75 to 100 feet.

-

-MM Wertheim and Breguet have propagated sound over the wire of an

-electric telegraph at the rate of 11,454 feet per second.

-

-

-DISTANCE AT WHICH THE HUMAN VOICE MAY BE HEARD.

-

-Experience shows that the human voice, under favourable circumstances,

-is capable of filling a larger space than was ever probably enclosed

-within the walls of a single room. Lieutenant Foster, on Parry’s third

-Arctic expedition, found that he could converse with a man across the

-harbour of Port Bowen, a distance of 6696 feet, or about one mile and a

-quarter. Dr. Young records that at Gibraltar the human voice has been

-heard at a distance of ten miles. If sound be prevented from spreading

-and losing itself in the air, either by a pipe or an extensive flat

-surface, as a wall or still water, it may be conveyed to a great

-distance. Biot heard a flute clearly through a tube of cast-iron (the

-water-pipes of Paris) 3120 feet long: the lowest whisper was distinctly

-heard; indeed, the only way not to be heard was not to speak at all.

-

-

-THE ROAR OF NIAGARA.

-

-The very nature of the sound of running water pronounces its origin

-to be the bursting of bubbles: the impact of water against water is a

-comparatively subordinate cause, and could never of itself occasion the

-murmur of a brook; whereas, in streams which Dr. Tyndall has examined,

-he, in all cases where a ripple was heard, discovered bubbles caused by

-the broken column of water. Now, were Niagara continuous, and without

-lateral vibration, it would be as silent as a cataract of ice. In all

-probability, it has its “contracted sections,” after passing which

-it is broken into detached masses, which, plunging successively upon

-the air-bladders formed by their precursors, suddenly liberate their

-contents, and thus create _the thunder of the waterfall_.

-

-

-FIGURES PRODUCED BY SOUND.

-

-Stretch a sheet of wet paper over the mouth of a glass tumbler which

-has a footstalk, and glue or paste the paper at the edges. When the

-paper is dry, strew dry sand thinly upon its surface. Place the tumbler

-on a table, and hold immediately above it, and parallel to the paper,

-a plate of glass, which you also strew with sand, having previously

-rubbed the edges smooth with emery powder. Draw a violin-bow along any

-part of the edges; and as the sand upon the glass is made to vibrate,

-it will form various figures, which will be accurately imitated by the

-sand upon the paper; or if a violin or flute be played within a few

-inches of the paper, they will cause the sand upon its surface to form

-regular lines and figures.

-

-

-THE TUNING-FORK A FLUTE-PLAYER.

-

-Take a common tuning-fork, and on one of its branches fasten with

-sealing-wax a circular piece of card of the size of a small wafer, or

-sufficient nearly to cover the aperture of a pipe, as the sliding of

-the upper end of a flute with the mouth stopped: it may be tuned in

-unison with the loaded tuning-fork by means of the movable stopper or

-card, or the fork may be loaded till the unison is perfect. Then set

-the fork in vibration by a blow on the unloaded branch, and hold the

-card closely over the mouth of the pipe, as in the engraving, when a

-note of surprising clearness and strength will be heard. Indeed a flute

-may be made to “speak” perfectly well, by holding close to the opening

-a vibrating tuning-fork, while the fingering proper to the note of the

-fork is at the same time performed.

-

-

-THEORY OF THE JEW’S HARP.

-

-If you cause the tongue of this little instrument to vibrate, it will

-produce a very low sound; but if you place it before a cavity (as the

-mouth) containing a column of air, which vibrates much faster, but

-in the proportion of any simple multiple, it will then produce other

-higher sounds, dependent upon the reciprocation of that portion of

-the air. Now the bulk of air in the mouth can be altered in its form,

-size, and other circumstances, so as to produce by reciprocation many

-different sounds; and these are the sounds belonging to the Jew’s Harp.

-

-A proof of this fact has been given by Mr. Eulenstein, who fitted into

-a long metallic tube a piston, which being moved, could be made to

-lengthen or shorten the efficient column of air within at pleasure. A

-Jew’s Harp was then so fixed that it could be made to vibrate before

-the mouth of the tube, and it was found that the column of air produced

-a series of sounds, according as it was lengthened or shortened; a

-sound being produced whenever the length of the column was such that

-its vibrations were a multiple of those of the Jew’s Harp.

-

-

-SOLAR AND ARTIFICIAL LIGHT COMPARED.

-

-The most intensely ignited solid (produced by the flame of Lieutenant

-Drummond’s oxy-hydrogen lamp directed against a surface of chalk)

-appears only as black spots on the disc of the sun, when held between

-it and the eye; or in other words, Drummond’s light is to the light of

-the sun’s disc as 1 to 146. Hence we are doubly struck by the felicity

-with which Galileo, as early as 1612, by a series of conclusions on

-the smallness of the distance from the sun at which the disc of Venus

-was no longer visible to the naked eye, arrived at the result that

-the blackest nucleus of the sun’s spots was more luminous than the

-brightest portions of the full moon. (See “The Sun’s Light compared

-with Terrestrial Lights,” in _Things not generally Known_, pp. 4, 5.)

-

-

-SOURCE OF LIGHT.

-

-Mr. Robert Hunt, in a lecture delivered by him at the Russell

-Institution, “On the Physics of a Sunbeam,” mentions some experiments

-by Lord Brougham on the sunbeam, in which, by placing the edge of a

-sharp knife just within the limit of the light, the ray was inflected

-from its previous direction, and coloured red; and when another knife

-was placed on the opposite side, it was deflected, and the colour was

-blue. These experiments (says Mr. Hunt) seem to confirm Sir Isaac

-Newton’s theory, that light is a fluid emitted from the sun.

-

-

-THE UNDULATORY SCALE OF LIGHT.

-

-The white light of the sun is well known to be composed of several

-coloured rays; or rather, according to the theory of undulations, when

-the rate at which a ray vibrates is altered, a different sensation

-is produced upon the optic nerve. The analytical examination of

-this question shows that to produce a red colour the ray of light

-must give 37,640 undulations in an inch, and 458,000,000,000,000 in

-a second. Yellow light requires 44,000 undulations in an inch, and

-535,000,000,000,000 in a second; whilst the effect of blue results from

-51,110 undulations within an inch, and 622,000,000,000,000 of waves in

-a second of time.--_Hunt’s Poetry of Science._

-

-

-VISIBILITY OF OBJECTS.

-

-In terrestrial objects, the form, no less than the modes of

-illumination, determines the magnitude of the smallest angle of vision

-for the naked eye. Adams very correctly observed that a long and

-slender staff can be seen at a much greater distance than a square

-whose sides are equal to the diameter of the staff. A stripe may be

-distinguished at a greater distance than a spot, even when both are of

-the same diameter.

-

-The _minimum_ optical visual angle at which terrestrial objects can

-be recognised by the naked eye has been gradually estimated lower and

-lower, from the time when Robert Hooke fixed it exactly at a full

-minute, and Tobias Meyer required 34″ to perceive a black speck on

-white paper, to the period of Leuwenhoeck’s experiments with spiders’

-threads, which are visible to ordinary sight at an angle of 4″·7. In

-Hueck’s most accurate experiments on the problem of the movement of

-the crystalline lens, white lines on a black ground were seen at an

-angle of 1″·2; a spider’s thread at 0″·6; and a fine glistening wire at

-scarcely 0″·2.

-

-  Humboldt, when at Chillo, near Quito, where the crests of the

-  volcano of Pichincha lay at a horizontal distance of 90,000 feet,

-  was much struck by the circumstance that the Indians standing near

-  distinguished the figure of Bonpland (then on an expedition to the

-  volcano), as a white point moving on the black basaltic sides of

-  the rock, sooner than Humboldt could discover him with a telescope.

-  Bonpland was enveloped in a white cotton poncho: assuming the

-  breadth across the shoulders to vary from three to five feet,

-  according as the mantle clung to the figure or fluttered in the

-  breeze, and judging from the known distance, the angle at which the

-  moving object could be distinctly seen varied from 7″ to 12″. White

-  objects on a black ground are, according to Hueck, distinguished at

-  a greater distance than black objects on a white ground.

-

-  Gauss’s heliotrope light has been seen with the naked eye reflected

-  from the Brocken on Hobenhagen at a distance of about 227,000 feet,

-  or more than 42 miles; being frequently visible at points in which

-  the apparent breadth of a three-inch mirror was only 0″·43.

-

-

-THE SMALLEST BRIGHT BODIES.

-

-Ehrenberg has found from experiments on the dust of diamonds, that

-a diamond superficies of 1/100th of a line in diameter presents a

-much more vivid light to the naked eye than one of quicksilver of the

-same diameter. On pressing small globules of quicksilver on a glass

-micrometer, he easily obtained smaller globules of the 1/100th to the

-1/2000th of a line in diameter. In the sunshine he could only discern

-the reflection of light, and the existence of such globules as were

-1/300th of a line in diameter, with the naked eye. Smaller ones did

-not affect his eye; but he remarked that the actual bright part of the

-globule did not amount to more than 1/900th of a line in diameter.

-Spider threads of 1/2000th in diameter were still discernible from

-their lustre. Ehrenberg concludes that there are in organic bodies

-magnitudes capable of direct proof which are in diameter 1/100000 of a

-line; and others, that can be indirectly proved, which may be less than

-a six-millionth part of a Parisian line in diameter.

-

-

-VELOCITY OF LIGHT.

-

-It is scarcely possible so to strain the imagination as to conceive

-the Velocity with which Light travels. “What mere assertion will make

-any man believe,” asks Sir John Herschel, “that in one second of time,

-in one beat of the pendulum of a clock, a ray of light travels over

-192,000 miles; and would therefore perform the tour of the world in

-about the same time that it requires to wink with our eyelids, and in

-much less time than a swift runner occupies in taking a single stride?”

-Were a cannon-ball shot directly towards the sun, and were it to

-maintain its full speed, it would be twenty years in reaching it; and

-yet light travels through this space in seven or eight minutes.

-

-The result given in the _Annuaire_ for 1842 for the velocity of light

-in a second is 77,000 leagues, which corresponds to 215,834 miles;

-while that obtained at the Pulkowa Observatory is 189,746 miles.

-William Richardson gives as the result of the passage of light from the

-sun to the earth 8´ 19″·28, from which we obtain a velocity of 215,392

-miles in a second.--_Memoirs of the Astronomical Society_, vol. iv.

-

-In other words, light travels a distance equal to eight times the

-circumference of the earth between two beats of a clock. This is a

-prodigious velocity; but the measure of it is very certain.--_Professor

-Airy._

-

-The navigator who has measured the earth’s circuit by his hourly

-progress, or the astronomer who has paced a degree of the meridian, can

-alone form a clear idea of velocity, when we tell him that light moves

-through a space equal to the circumference of the earth in _the eighth

-part of a second_--in the twinkling of an eye.

-

-  Could an observer, placed in the centre of the earth, see this

-  moving light, as it describes the earth’s circumference, it would

-  appear a luminous ring; that is, the impression of the light at the

-  commencement of its journey would continue on the retina till the

-  light had completed its circuit. Nay, since the impression of light

-  continues longer than the _fourth_ part of a second, _two_ luminous

-  rings would be seen, provided the light made _two_ rounds of the

-  earth, and in paths not coincident.

-

-

-APPARATUS FOR THE MEASUREMENT OF LIGHT.

-

-Humboldt enumerates the following different methods adopted for the

-Measurement of Light: a comparison of the shadows of artificial lights,

-differing in numbers and distance; diaphragms; plane-glasses of

-different thickness and colour; artificial stars formed by reflection

-on glass spheres; the juxtaposition of two seven-feet telescopes,

-separated by a distance which the observer could pass in about a

-second; reflecting instruments in which two stars can be simultaneously

-seen and compared, when the telescope has been so adjusted that the

-star gives two images of like intensity; an apparatus having (in

-front of the object-glass) a mirror and diaphragms, whose rotation

-is measured on a ring; telescopes with divided object-glasses, on

-either half of which the stellar light is received through a prism;

-astrometers, in which a prism reflects the image of the moon or

-Jupiter, and concentrates it through a lens at different distances into

-a star more or less bright.--_Cosmos_, vol. iii.

-

-

-HOW FIZEAU MEASURED THE VELOCITY OF LIGHT.

-

-This distinguished physicist has submitted the Velocity of Light

-to terrestrial measurement by means of an ingeniously constructed

-apparatus, in which artificial light (resembling stellar light),

-generated from oxygen and hydrogen, is made to pass back, by means of

-a mirror, over a distance of 28,321 feet to the same point from which

-it emanated. A disc, having 720 teeth, which made 12·6 rotations in a

-second, alternately obscured the ray of light and allowed it to be seen

-between the teeth on the margin. It was supposed, from the marking of

-a counter, that the artificial light traversed 56,642 feet, or the

-distance to and from the stations, in 1/1800th part of a second, whence

-we obtain a velocity of 191,460 miles in a second.[12] This result

-approximates most closely to Delambre’s (which was 189,173 miles), as

-obtained from Jupiter’s satellites.

-

-  The invention of the rotating mirror is due to Wheatstone, who made

-  an experiment with it to determine the velocity of the propagation

-  of the discharge of a Leyden battery. The most striking application

-  of the idea was made by Fizeau and Foucault, in 1853, in carrying

-  out a proposition made by Arago, soon after the invention of the

-  mirror: we have here determined in a distance of twelve feet no

-  less than the velocity with which light is propagated, which is

-  known to be nearly 200,000 miles a second; the distance mentioned

-  corresponds therefore to the 77-millionth part of a second. The

-  object of these measurements was to compare the velocity of light

-  in air with its velocity in water; which, when the length is

-  greater, is not sufficiently transparent. The most complete optical

-  and mechanical aids are here necessary: the mirror of Foucault

-  made from 600 to 800 revolutions in a second, while that of Fizeau

-  performed 1200 to 1500 in the same time.--_Prof. Helmholtz on the

-  Methods of Measuring very small Portions of Time._

-

-

-WHAT IS DONE BY POLARISATION OF LIGHT.

-

-Malus, in 1808, was led by a casual observation of the light of the

-setting sun, reflected from the windows of the Palais de Luxembourg,

-at Paris, to investigate more thoroughly the phenomena of double

-refraction, of ordinary and of chromatic polarisation, of interference

-and of diffraction of light. Among his results may be reckoned the

-means of distinguishing between direct and reflected light; the power

-of penetrating, as it were, into the constitution of the body of

-the sun and of its luminous envelopes; of measuring the pressure of

-atmospheric strata, and even the smallest amount of water they contain;

-of ascertaining the depths of the ocean and its rocks by means of

-a tourmaline plate; and in accordance with Newton’s prediction, of

-comparing the chemical composition of several substances with their

-optical effects.

-

-  Arago, in a letter to Humboldt, states that by the aid of his

-  polariscope, he discovered, before 1820, that the light of all

-  terrestrial objects in a state of incandescence, whether they be

-  solid or liquid, is natural, so long as it emanates from the object

-  in perpendicular rays. On the other hand, if such light emanate

-  at an acute angle, it presents manifest proofs of polarisation.

-  This led M. Arago to the remarkable conclusion, that light is not

-  generated on the surface of bodies only, but that some portion is

-  actually engendered within the substance itself, even in the case

-  of platinum.

-

-A ray of light which reaches our eyes after traversing many millions

-of miles, from, the remotest regions of heaven, announces, as it were

-of itself, in the polariscope, whether it is reflected or refracted,

-whether it emanates from a solid or fluid or gaseous body; it announces

-even the degree of its intensity.--_Humboldt’s Cosmos_, vols. i. and ii.

-

-

-MINUTENESS OF LIGHT.

-

-There is something wonderful, says Arago, in the experiments which have

-led natural philosophers legitimately to talk of the different sides of

-a ray of light; and to show that millions and millions of these rays

-can simultaneously pass through the eye of a needle without interfering

-with each other!

-

-

-THE IMPORTANCE OF LIGHT.

-

-Light affects the respiration of animals just as it affects the

-respiration of plants. This is novel doctrine, but it is demonstrable.

-In the day-time we expire more carbonic acid than during the night; a

-fact known to physiologists, who explain it as the effect of sleep: but

-the difference is mainly owing to the presence or absence of sunlight;

-for sleep, as sleep, _increases_, instead of diminishing, the amount

-of carbonic acid expired, and a man sleeping will expire more carbonic

-acid than if he lies quietly awake under the same conditions of light

-and temperature; so that if less is expired during the night than

-during the day, the reason cannot be sleep, but the absence of light.

-Now we understand why men are sickly and stunted who live in narrow

-streets, alleys, and cellars, compared with those who, under similar

-conditions of poverty and dirt, live in the sunlight.--_Blackwood’s

-Edinburgh Magazine_, 1858.

-

-  The influence of light on the colours of organised creation is well

-  shown in the sea. Near the shores we find seaweeds of the most

-  beautiful hues, particularly on the rocks which are left dry by

-  the tides; and the rich tints of the actiniæ which inhabit shallow

-  water must often have been observed. The fishes which swim near the

-  surface are also distinguished by the variety of their colours,

-  whereas those which live at greater depths are gray, brown, or

-  black. It has been found that after a certain depth, where the

-  quantity of light is so reduced that a mere twilight prevails, the

-  inhabitants of the ocean become nearly colourless.--_Hunt’s Poetry

-  of Science._

-

-

-ACTION OF LIGHT ON MUSCULAR FIBRES.

-

-That light is capable of acting on muscular fibres, independently

-of the influence of the nerves, was mentioned by several of the old

-anatomists, but repudiated by later authorities. M. Brown Séquard has,

-however, proved to the Royal Society that some portions of muscular

-fibre--the iris of the eye, for example--are affected by light

-independently of any reflex action of the nerves, thereby confirming

-former experiences. The effect is produced by the illuminating rays

-only, the chemical and heat rays remaining neutral. And not least

-remarkable is the fact, that the iris of an eel showed itself

-susceptible of the excitement _sixteen days after the eyes were removed

-from the creature’s head_. So far as is yet known, this muscle is the

-only one on which light thus takes effect.--_Phil. Trans. 1857._

-

-

-LIGHT NIGHTS.

-

-It is not possible, as well-attested facts prove, perfectly to explain

-the operations at work in the much-contested upper boundaries of

-our atmosphere. The extraordinary lightness of whole nights in the

-year 1831, during which small print might be read at midnight in

-the latitudes of Italy and the north of Germany, is a fact directly

-at variance with all that we know, according to the most recent and

-acute researches on the crepuscular theory and the height of the

-atmosphere.--_Biot._

-

-

-PHOSPHORESCENCE OF PLANTS.

-

-Mr. Hunt recounts these striking instances. The leaves of the _œnothera

-macrocarpa_ are said to exhibit phosphoric light when the air is

-highly charged with electricity. The agarics of the olive-grounds of

-Montpelier too have been observed to be luminous at night; but they

-are said to exhibit no light, even in darkness, _during the day_. The

-subterranean passages of the coal-mines near Dresden are illuminated by

-the phosphorescent light of the _rhizomorpha phosphoreus_, a peculiar

-fungus. On the leaves of the Pindoba palm grows a species of agaric

-which is exceedingly luminous at night; and many varieties of the

-lichens, creeping along the roofs of caverns, lend to them an air of

-enchantment by the soft and clear light which they diffuse. In a small

-cave near Penryn, a luminous moss is abundant; it is also found in the

-mines of Hesse. According to Heinzmann, the _rhizomorpha subterranea_

-and _aidulæ_ are also phosphorescent.--See _Poetry of Science_.

-

-

-PHOSPHORESCENCE OF THE SEA.

-

-By microscopic examination of the myriads of minute insects which cause

-this phenomenon, no other fact has been elicited than that they contain

-a fluid which, when squeezed out, leaves a train of light upon the

-surface of the water. The creatures appear almost invariably on the eve

-of some change of weather, which would lead us to suppose that their

-luminous phenomena must be connected with electrical excitation; and of

-this Mr. C. Peach of Fowey has furnished the most satisfactory proofs

-yet obtained.[13]

-

-

-LIGHT FROM THE JUICE OF A PLANT.

-

-In Brazil has been observed a plant, conjectured to be an Euphorbium,

-very remarkable for the light which it yields when cut. It contains a

-milky juice, which exudes as soon as the plant is wounded, and appears

-luminous for several seconds.

-

-

-LIGHT FROM FUNGUS.

-

-Phosphorescent funguses have been found in Brazil by Mr. Gardner,

-growing on the decaying leaves of a dwarf palm. They vary from one to

-two inches across, and the whole plant gives out at night a bright

-phosphorescent light, of a pale greenish hue, similar to that emitted

-by fire-flies and phosphorescent marine animals. The light given out by

-a few of these fungi in a dark room is sufficient to read by. A very

-large phosphorescent species is occasionally found in the Swan River

-colony.

-

-

-LIGHT FROM BUTTONS.

-

-Upon highly polished gilt buttons no figure whatever can be seen by the

-most careful examination; yet, when they are made to reflect the light

-of the sun or of a candle upon a piece of paper held close to them,

-they give a beautiful geometrical figure, with ten rays issuing from

-the centre, and terminating in a luminous rim.

-

-

-COLOURS OF SCRATCHES.

-

-An extremely fine scratch on a well-polished surface may be regarded as

-having a concave, cylindrical, or at least a curved surface, capable of

-reflecting light in all directions; this is evident, for it is visible

-in all directions. Hence a single scratch or furrow in a surface may

-produce colours by the interference of the rays reflected from its

-opposite edges. Examine a spider’s thread in the sunshine, and it will

-gleam with vivid colours. These may arise from a similar cause; or from

-the thread itself, as spun by the animal, consisting of several threads

-agglutinated together, and thus presenting, not a cylindrical, but a

-furrowed surface.

-

-

-MAGIC BUST.

-

-Sir David Brewster has shown how the rigid features of a white bust

-may be made to move and vary their expression, sometimes smiling and

-sometimes frowning, by moving rapidly in front of the bust a bright

-light, so as to make the lights and shadows take every possible

-direction and various degrees of intensity; and if the bust be placed

-before a concave mirror, its image may be made to do still more when it

-is cast upon wreaths of smoke.

-

-

-COLOURS HIT MOST FREQUENTLY DURING BATTLE.

-

-It would appear from numerous observations that soldiers are hit

-during battle according to the colour of their dress in the following

-order: red is the most fatal colour; the least fatal, Austrian gray.

-The proportions are, red, 12; rifle-green, 7; brown, 6; Austrian

-bluish-gray, 5.--_Jameson’s Journal_, 1853.

-

-

-TRANSMUTATION OF TOPAZ.

-

-Yellow topazes may be converted into pink by heat; but it is a mistake

-to suppose that in the process the yellow colour is changed into pink:

-the fact is, that one of the pencils being yellow and the other pink,

-the yellow is discharged by heat, thus leaving the pink unimpaired.

-

-

-COLOURS AND TINTS.

-

-M. Chevreul, the _Directeur des Gobelins_, has presented to the French

-Academy a plan for a universal chromatic scale, and a methodical

-classification of all imaginable colours. Mayer, a professor at

-Göttingen, calculated that the different combinations of primitive

-colours produced 819 different tints; but M. Chevreul established not

-less than 14,424, all very distinct and easily recognised,--all of

-course proceeding from the three primitive simple colours of the solar

-spectrum, red, yellow, and blue. For example, he states that in the

-violet there are twenty-eight colours, and in the dahlia forty-two.

-

-

-OBJECTS REALLY OF NO COLOUR.

-

-A body appears to be of the colour which it reflects; as we see it only

-by reflected rays, it can but appear of the colour of those rays. Thus

-grass is green because it absorbs all except the green rays. Flowers,

-in the same manner, reflect the various colours of which they appear

-to us: the rose, the red rays; the violet, the blue; the daffodil,

-the yellow, &c. But these are not the permanent colours of the grass

-and flowers; for wherever you see these colours, the objects must be

-illuminated; and light, from whatever source it proceeds, is of the

-same nature, composed of the various coloured rays which paint the

-grass, the flowers, and every coloured object in nature. Objects in

-the dark have no colour, or are black, which is the same thing. You

-can never see objects without light. Light is composed of colours,

-therefore there can be no light without colours; and though every

-object is black or without colour in the dark, it becomes coloured as

-soon as it becomes visible.

-

-

-THE DIORAMA--WHY SO PERFECT AN ILLUSION.

-

-Because when an object is viewed at so great a distance that the

-optic axes of both eyes are sensibly parallel when directed towards

-it, the perspective projections of it, seen by each eye separately,

-are similar; and the appearance to the two eyes is precisely the same

-as when the object is seen by one eye only. There is, in such case,

-no difference between the visual appearance of an object in relief

-and its perspective projection on a plane surface; hence pictorial

-representations of distant objects, when those circumstances which

-would prevent or disturb the illusion are carefully excluded, may be

-rendered such perfect resemblances of the objects they are intended to

-represent as to be mistaken for them. The Diorama is an instance of

-this.--_Professor Wheatstone_; _Philosophical Transactions_, 1838.

-

-

-CURIOUS OPTICAL EFFECTS AT THE CAPE.

-

-Sir John Herschel, in his observatory at Feldhausen, at the base of

-the Table Mountain, witnessed several curious optical effects, arising

-from peculiar conditions of the atmosphere incident to the climate of

-the Cape. In the hot season “the nights are for the most part superb;”

-but occasionally, during the excessive heat and dryness of the sandy

-plains, “the optical tranquillity of the air” is greatly disturbed.

-In some cases, the images of the stars are violently dilated into

-nebular balls or puffs of 15′ in diameter; on other occasions they

-form “soft, round, quiet pellets of 3′ or 4′ diameter,” resembling

-planetary nebulæ. In the cooler months the tranquillity of the image

-and the sharpness of vision are such, that hardly any limit is set

-to magnifying power but that which arises from the aberration of the

-specula. On occasions like these, optical phenomena of extraordinary

-splendour are produced by viewing a bright star through a diaphragm

-of cardboard or zinc pierced in regular patterns of circular holes by

-machinery: these phenomena surprise and delight every person that sees

-them. When close double stars are viewed with the telescope, with a

-diaphragm in the form of an equilateral triangle, the discs of the two

-stars, which are exact circles, have a clearness and perfection almost

-incredible.

-

-

-THE TELESCOPE AND THE MICROSCOPE.

-

-So singular is the position of the Telescope and the Microscope among

-the great inventions of the age, that no other process but that which

-they embody could make the slightest approximation to the secrets which

-they disclose. The steam-engine might have been imperfectly replaced

-by an air or an ether-engine; and a highly elastic fluid might have

-been, and may yet be, found, which shall impel the “rapid car,” or

-drag the merchant-ship over the globe. The electric telegraph, now so

-perfect and unerring, might have spoken to us in the rude “language

-of chimes;” or sound, in place of electricity, might have passed along

-the metallic path, and appealed to the ear in place of the eye. For

-the printing-press and the typographic art might have been found a

-substitute, however poor, in the lithographic process; and knowledge

-might have been widely diffused by the photographic printing powers

-of the sun, or even artificial light. But without the telescope and

-the microscope, the human eye would have struggled in vain to study

-the worlds beyond our own, and the elaborate structures of the organic

-and inorganic creation could never have been revealed.--_North-British

-Review_, No. 50.

-

-

-INVENTION OF THE MICROSCOPE.

-

-The earliest magnifying lens of which we have any knowledge was one

-rudely made of rock-crystal, which Mr. Layard found, among a number

-of glass bowls, in the north-west palace of Nimroud; but no similar

-lens has been found or described to induce us to believe that the

-microscope, either single or compound, was invented and used as an

-instrument previous to the commencement of the seventeenth century.

-In the beginning of the first century, however, Seneca alludes to the

-magnifying power of a glass globe filled with water; but as he only

-states that it made small and indistinct letters appear larger and more

-distinct, we cannot consider such a casual remark as the invention of

-the single microscope, though it might have led the observer to try the

-effect of smaller globes, and thus obtain magnifying powers sufficient

-to discover phenomena otherwise invisible.

-

-Lenses of glass were undoubtedly in existence at the time of Pliny;

-but at that period, and for many centuries afterwards, they appear

-to have been used only as burning or as reading glasses; and no

-attempt seems to have been made to form them of so small a size as

-to entitle them to be regarded even as the precursors of the single

-microscope.--_North-British Review_, No. 50.

-

-  The _rock-crystal lens_ found at Nineveh was examined by Sir

-  David Brewster. It was not entirely circular in its aperture. Its

-  general form was that of a plano-convex lens, the plane side having

-  been formed of one of the original faces of the six-sided crystal

-  quartz, as Sir David ascertained by its action on polarised light:

-  this was badly polished and scratched. The convex face of the lens

-  had not been ground in a dish-shaped tool, in the manner in which

-  lenses are now formed, but was shaped on a lapidary’s wheel, or in

-  some such manner. Hence it was unequally thick; but its extreme

-  thickness was 2/10ths of an inch, its focal length being 4½ inches.

-  It had twelve remains of cavities, which had originally contained

-  liquids or condensed gases. Sir David has assigned reasons why this

-  could not be looked upon as an ornament, but a true optical lens.

-  In the same ruins were found some decomposed glass.

-

-

-HOW TO MAKE THE FISH-EYE MICROSCOPE.

-

-Very good microscopes may be made with the crystalline lenses of

-fish, birds, and quadrupeds. As the lens of fishes is spherical or

-spheroidal, it is absolutely necessary, previous to its use, to

-determine its optical axis and the axis of vision of the eye from which

-it is taken, and place the lens in such a manner that its axis is a

-continuation of the axis of our own eye. In no other direction but this

-is the albumen of which the lens consists symmetrically disposed in

-laminæ of equal density round a given line, which is the axis of the

-lens; and in no other direction does the gradation of density, by which

-the spherical aberration is corrected, preserve a proper relation to

-the axis of vision.

-

-  When the lens of any small fish, such as a minnow, a par, or trout,

-  has been taken out, along with the adhering vitreous humour, from

-  the eye-ball by cutting the sclerotic coat with a pair of scissors,

-  it should be placed upon a piece of fine silver-paper previously

-  freed from its minute adhering fibres. The absorbent nature of

-  the paper will assist in removing all the vitreous humour from

-  the lens; and when this is carefully done, by rolling it about

-  with another piece of silver-paper, there will still remain,

-  round or near the equator of the lens, a black ridge, consisting

-  of the processes by which it was suspended in the eye-ball. The

-  black circle points out to us the true axis of the lens, which

-  is perpendicular to a plane passing through it. When the small

-  crystalline has been freed from all the adhering vitreous humour,

-  the capsule which contains it will have a surface as fine as a

-  pellicle of fluid. It is then to be dropped from the paper into a

-  cavity formed by a brass rim, and its position changed till the

-  black circle is parallel to the circular rim, in which case only

-  the axis of the lens will be a continuation of the axis of the

-  observer’s eye.--_Edin. Jour. Science_, vol. ii.

-

-

-LEUWENHOECK’S MICROSCOPES.

-

-Leuwenhoeck, the father of microscopical discovery, communicated to the

-Royal Society, in 1673, a description of the structure of a bee and a

-louse, seen by aid of his improved microscopes; and from this period

-until his decease in 1723, he regularly transmitted to the society his

-microscopical observations and discoveries, so that 375 of his papers

-and letters are preserved in the society’s archives, extending over

-fifty years. He further bequeathed to the Royal Society a cabinet of

-twenty-six microscopes, which he had ground himself and set in silver,

-mostly extracted by him from minerals; these microscopes were exhibited

-to Peter the Great when he was at Delft in 1698. In acknowledging

-the bequest, the council of the Royal Society, in 1724, presented

-Leuwenhoeck’s daughter with a handsome silver bowl, bearing the arms of

-the society.--_Weld’s History of the Royal Society_, vol. i.

-

-

-DIAMOND LENSES FOR MICROSCOPES.

-

-In recommending the employment of Diamond and other gems in the

-construction of Microscopes, Sir David Brewster has been met with

-the objection that they are too expensive for such a purpose; and,

-says Sir David, “they certainly are for instruments intended merely

-to instruct and amuse. But if we desire to make great discoveries,

-to unfold secrets yet hid in the cells of plants and animals, we

-must not grudge even a diamond to reveal them. If Mr. Cooper and Sir

-James South have given a couple of thousand pounds a piece for a

-refracting telescope, in order to study what have been miscalled ‘dots’

-and ‘lumps’ of light on the sky; and if Lord Rosse has expended far

-greater sums on a reflecting telescope for analysing what has been

-called ‘sparks of mud and vapour’ encumbering the azure purity of the

-heavens,--why should not other philosophers open their purse, if they

-have one, and other noblemen sacrifice some of their household jewels,

-to resolve the microscopic structures of our own real world, and

-disclose secrets which the Almighty must have intended that we should

-know?”--_Proceedings of the British Association_, 1857.

-

-

-THE EYE AND THE BRAIN SEEN THROUGH A MICROSCOPE.

-

-By a microscopic examination of the retina and optic nerve and

-the brain, M. Bauer found them to consist of globules of 1/2800th

-to 1/4000th an inch diameter, united by a transparent viscid and

-coagulable gelatinous fluid.

-

-

-MICROSCOPICAL EXAMINATION OF THE HAIR.

-

-If a hair be drawn between the finger and thumb, from the end to

-the root, it will be distinctly felt to give a greater resistance

-and a different sensation to that which is experienced when drawn

-the opposite way: in consequence, if the hair be rubbed between the

-fingers, it will only move one way (travelling in the direction of a

-line drawn from its termination to its origin from the head or body),

-so that each extremity may thus be easily distinguished, even in the

-dark, by the touch alone.

-

-The mystery is resolved by the achromatic microscope. A hair viewed on

-a dark ground as an _opaque_ object with a high power, not less than

-that of a lens of one-thirtieth of an inch focus, and dully illuminated

-by a _cup_, the hair is seen to be indented with teeth somewhat

-resembling those of a coarse round rasp, but extremely irregular and

-rugged: as these incline all in one direction, like those of a common

-file, viz. from the origin of the hair towards its extremity, it

-sufficiently explains the above singular property.

-

-This is a singular proof of the acuteness of the sense of feeling, for

-the said teeth may be felt much more easily than they can be seen. We

-may thus understand why a razor will cut a hair in two much more easily

-when drawn against its teeth than in the opposite direction.--_Dr.

-Goring._

-

-

-THE MICROSCOPE AND THE SEA.

-

-What myriads has the microscope revealed to us of the rich luxuriance

-of animal life in the ocean, and conveyed to our astonished senses

-a consciousness of the universality of life! In the oceanic depths

-every stratum of water is animated, and swarms with countless hosts of

-small luminiferous animalcules, mammaria, crustacea, peridinea, and

-circling nereides, which, when attracted to the surface by peculiar

-meteorological conditions, convert every wave into a foaming band of

-flashing light.

-

-

-USE OF THE MICROSCOPE TO MINERALOGISTS.

-

-M. Dufour has shown that an imponderable quantity of a substance

-can be crystallised; and that the crystals so obtained are quite

-characteristic of the substances, as of sugar, chloride of sodium,

-arsenic, and mercury. This process may be extremely valuable to the

-mineralogist and toxicologist when the substance for examination is too

-small to be submitted to tests. By aid of the microscope, also, shells

-are measured to the thousandth part of an inch.

-

-

-FINE DOWN OF QUARTZ.

-

-Sir David Brewster having broken in two a crystal of quartz of a smoky

-colour, found both surfaces of the fracture absolutely black; and the

-blackness appeared at first sight to be owing to a thin film of opaque

-matter which had insinuated itself into the crevice. This opinion,

-however, was untenable, as every part of the surface was black, and

-the two halves of the crystals could not have stuck together had the

-crevice extended across the whole section. Upon further examination Sir

-David found that the surface was perfectly transparent by transmitted

-light, and that the blackness of the surfaces arose from their being

-entirely composed of _a fine down of quartz_, or of short and slender

-filaments, whose diameter was so exceedingly small that they were

-incapable of reflecting a single ray of the strongest light; and they

-could not exceed the _one third of the millionth part of an inch_. This

-curious specimen is in the cabinet of her grace the Duchess of Gordon.

-

-

-MICROSCOPIC WRITING.

-

-Professor Kelland has shown, in Paris, on a spot no larger than

-the head of a small pin, by means of powerful microscopes, several

-specimens of distinct and beautiful writing, one of them containing

-the whole of the Lord’s Prayer written within this minute compass.

-In reference to this, two remarkable facts in Layard’s latest work

-on Nineveh show that the national records of Assyria were written on

-square bricks, in characters so small as scarcely to be legible without

-a microscope; in fact, a microscope, as we have just shown, was found

-in the ruins of Nimroud.

-

-

-HOW TO MAKE A MAGIC MIRROR.

-

-Draw a figure with weak gum-water upon the surface of a convex mirror.

-The thin film of gum thus deposited on the outline or details of the

-figure will not be visible in dispersed daylight; but when made to

-reflect the rays of the sun, or those of a divergent pencil, will

-be beautifully displayed by the lines and tints occasioned by the

-diffraction of light, or the interference of the rays passing through

-the film with those which pass by it.

-

-

-SIR DAVID BREWSTER’S KALEIDOSCOPE.

-

-The idea of this instrument, constructed for the purpose of creating

-and exhibiting a variety of beautiful and perfectly symmetrical forms,

-first occurred to Sir David Brewster in 1814, when he was engaged in

-experiments on the polarisation of light by successive reflections

-between plates of glass. The reflectors were in some instances inclined

-to each other; and he had occasion to remark the circular arrangement

-of the images of a candle round a centre, or the multiplication of the

-sectors formed by the extremities of the glass plates. In repeating

-at a subsequent period the experiments of M. Biot on the action of

-fluids upon light, Sir David Brewster placed the fluids in a trough,

-formed by two plates of glass cemented together at an angle; and the

-eye being necessarily placed at one end, some of the cement, which had

-been pressed through between the plates, appeared to be arranged into a

-regular figure. The remarkable symmetry which it presented led to Dr.

-Brewster’s investigation of the cause of this phenomenon; and in so

-doing he discovered the leading principles of the Kaleidoscope.

-

-By the advice of his friends, Dr. Brewster took out a patent for his

-invention; in the specification of which he describes the kaleidoscope

-in two different forms. The instrument, however, having been shown

-to several opticians in London, became known before he could avail

-himself of his patent; and being simple in principle, it was at once

-largely manufactured. It is calculated that not less than 200,000

-kaleidoscopes were sold in three months in London and Paris; though out

-of this number, Dr. Brewster says, not perhaps 1000 were constructed

-upon scientific principles, or were capable of giving any thing like a

-correct idea of the power of his kaleidoscope.

-

-

-THE KALEIDOSCOPE THOUGHT TO BE ANTICIPATED.

-

-In the seventh edition of a work on gardening and planting, published

-in 1739, by Richard Bradley, F.R.S., late Professor of Botany in the

-University of Cambridge, we find the following details of an invention,

-“by which the best designers and draughtsmen may improve and help

-their fancies. They must choose two pieces of looking-glass of equal

-bigness, of the figure of a long square. These must be covered on

-the back with paper or silk, to prevent rubbing off the silver. This

-covering must be so put on that nothing of it appears about the edges

-of the bright side. The glasses being thus prepared, must be laid face

-to face, and hinged together so that they may be made to open and shut

-at pleasure like the leaves of a book.” After showing how various

-figures are to be looked at in these glasses under the same opening,

-and how the same figure may be varied under the different openings, the

-ingenious artist thus concludes: “If it should happen that the reader

-has any number of plans for parterres or wildernesses by him, he may by

-this method alter them at his pleasure, and produce such innumerable

-varieties as it is not possible the most able designer could ever have

-contrived.”

-

-

-MAGIC OF PHOTOGRAPHY.

-

-Professor Moser of Königsberg has discovered that all bodies, even

-in the dark, throw out invisible rays; and that these bodies, when

-placed at a small distance from polished surfaces of all kinds, depict

-themselves upon such surfaces in forms which remain invisible till

-they are developed by the human breath or by the vapours of mercury or

-iodine. Even if the sun’s image is made to pass over a plate of glass,

-the light tread of its rays will leave behind it an invisible track,

-which the human breath will instantly reveal.

-

-  Among the early attempts to take pictures by the rays of the sun

-  was a very interesting and successful experiment made by Dr. Thomas

-  Young. In 1802, when Mr. Wedgewood was “making profiles by the

-  agency of light,” and Sir Humphry Davy was “copying on prepared

-  paper the images of small objects produced by means of the solar

-  microscope,” Dr. Young was taking photographs upon paper dipped in

-  a solution of nitrate of silver, of the coloured rings observed

-  by Newton; and his experiments clearly proved that the agent was

-  not the luminous rays in the sun’s light, but the invisible or

-  chemical rays beyond the violet. This experiment is described in

-  the Bakerian Lecture, 1803.

-

-  Niepce (says Mr. Hunt) pursued a physical investigation of the

-  curious change, and found that all bodies were influenced by this

-  principle radiated from the sun. Daguerre[14] produced effects from

-  the solar pencil which no artist could approach; and Talbot and

-  others extended the application. Herschel took up the inquiry; and

-  he, with his usual power of inductive search and of philosophical

-  deduction, presented the world with a class of discoveries which

-  showed how vast a field of investigation was opening for the

-  younger races of mankind.

-

-  The first attempts in photography, which were made at the

-  instigation of M. Arago, by order of the French Government, to

-  copy the Egyptian tombs and temples and the remains of the Aztecs

-  in Central America, were failures. Although the photographers

-  employed succeeded to admiration, in Paris, in producing pictures

-  in a few minutes, they found often that an exposure of an hour

-  was insufficient under the bright and glowing illumination of a

-  southern sky.

-

-

-THE BEST SKY FOR PHOTOGRAPHY.

-

-Contrary to all preconceived ideas, experience proves that the brighter

-the sky that shines above the camera the more tardy the action within

-it. Italy and Malta do their work slower than Paris. Under the

-brilliant light of a Mexican sun, half an hour is required to produce

-effects which in England would occupy but a minute. In the burning

-atmosphere of India, though photographical the year round, the process

-is comparatively slow and difficult to manage; while in the clear,

-beautiful, and moreover cool, light of the higher Alps of Europe, it

-has been proved that the production of a picture requires many more

-minutes, even with the most sensitive preparations, than in the murky

-atmosphere of London. Upon the whole, the temperate skies of this

-country may be pronounced favourable to photographic action; a fact

-for which the prevailing characteristic of our climate may partially

-account, humidity being an indispensable condition for the working

-state both of paper and chemicals.--_Quarterly Review_, No. 202.

-

-

-PHOTOGRAPHIC EFFECTS OF LIGHTNING.

-

-The following authenticated instances of this singular phenomenon have

-been communicated to the Royal Society by Andrés Poey, Director of the

-Observatory at Havana:

-

-  Benjamin Franklin, in 1786, stated that about twenty years

-  previous, a man who was standing opposite a tree that had just been

-  struck by “a thunderbolt” had on his breast an exact representation

-  of that tree.

-

-  In the New-York _Journal of Commerce_, August 26th, 1853, it is

-  related that “a little girl was standing at a window, before which

-  was a young maple-tree; after a brilliant flash of lightning, a

-  complete image of the tree was found imprinted on her body.”

-

-  M. Raspail relates that, in 1855, a boy having climbed a tree for

-  the purpose of robbing a bird’s nest, the tree was struck, and

-  the boy thrown upon the ground; on his breast the image of the

-  tree, with the bird and nest on one of its branches, appeared very

-  plainly.

-

-  M. Olioli, a learned Italian, brought before the Scientific

-  Congress at Naples the following four instances: 1. In September

-  1825, the foremast of a brigantine in the Bay of St. Arniro

-  was struck by lightning, when a sailor sitting under the mast

-  was struck dead, and on his back was found an impression of a

-  horse-shoe, similar even in size to that fixed on the mast-head. 2.

-  A sailor, standing in a similar position, was struck by lightning,

-  and had on his left breast the impression of the number 4 4, with a

-  dot between the two figures, just as they appeared at the extremity

-  of one of the masts. 3. On the 9th October 1836, a young man was

-  found struck by lightning; he had on a girdle, with some gold

-  coins in it, which were imprinted on his skin in the order they

-  were placed in the girdle,--a series of circles, with one point of

-  contact, being plainly visible. 4. In 1847, Mme. Morosa, an Italian

-  lady of Lugano, was sitting near a window during a thunderstorm,

-  and perceived the commotion, but felt no injury; but a flower which

-  happened to be in the path of the electric current was perfectly

-  reproduced on one of her legs, and there remained permanently.

-

-  M. Poey himself witnessed the following instance in Cuba. On July

-  24th, 1852, a poplar-tree in a coffee-plantation was struck by

-  lightning, and on one of the large dry leaves was found an exact

-  representation of some pine-trees that lay 367 yards distant.

-

-M. Poey considers these lightning impressions to have been produced

-in the same manner as the electric images obtained by Moser, Riess,

-Karster, Grove, Fox Talbot, and others, either by statical or dynamical

-electricity of different intensities. The fact that impressions are

-made through the garments is easily accounted for by their rough

-texture not preventing the lightning passing through them with the

-impression. To corroborate this view, M. Poey mentions an instance of

-lightning passing down a chimney into a trunk, in which was found an

-inch depth of soot, which must have passed through the wood itself.

-

-

-PHOTOGRAPHIC SURVEYING.

-

-During the summer of 1854, in the Baltic, the British steamers employed

-in examining the enemy’s coasts and fortifications took photographic

-views for reference and minute examination. With the steamer moving

-at the rate of fifteen knots an hour, the most perfect definitions of

-coasts and batteries were obtained. Outlines of the coasts, correct in

-height and distance, have been faithfully transcribed; and all details

-of the fortresses passed under this photographic review are accurately

-recorded.

-

-  It is curious to reflect that the aids to photographic development

-  all date within the last half-century, and are but little older

-  than photography itself. It was not until 1811 that the chemical

-  substance called iodine, on which the foundations of all popular

-  photography rest, was discovered at all; bromine, the only other

-  substance equally sensitive, not till 1826. The invention of the

-  electro process was about simultaneous with that of photography

-  itself. Gutta-percha only just preceded the substance of which

-  collodion is made; the ether and chloroform, which are used in

-  some methods, that of collodion. We say nothing of the optical

-  improvements previously contrived or adapted for the purpose of the

-  photograph: the achromatic lenses, which correct the discrepancy

-  between the visual and chemical foci; the double lenses, which

-  increase the force of the action; the binocular lenses, which

-  do the work of the stereoscope; nor of the innumerable other

-  mechanical aids which have sprung up for its use.

-

-

-THE STEREOSCOPE AND THE PHOTOGRAPH.

-

-When once the availability of one great primitive agent is worked out,

-it is easy to foresee how extensively it will assist in unravelling

-other secrets in natural science. The simple principle of the

-Stereoscope, for instance, might have been discovered a century ago,

-for the reasoning which led to it was independent of all the properties

-of light; but it could never have been illustrated, far less multiplied

-as it now is, without Photography. A few diagrams, of sufficient

-identity and difference to prove the truth of the principle, might

-have been constructed by hand, for the gratification of a few sages;

-but no artist, it is to be hoped, could have been found possessing

-the requisite ability and stupidity to execute the two portraits, or

-two groups, or two interiors, or two landscapes, identical in every

-minutia of the most elaborate detail, and yet differing in point of

-view by the inch between the two human eyes, by which the principle is

-brought to the level of any capacity. Here, therefore, the accuracy and

-insensibility of a machine could alone avail; and if in the order of

-things the cheap popular toy which the stereoscope now represents was

-necessary for the use of man, the photograph was first necessary for

-the service of the stereoscope.--_Quarterly Review_, No. 202.

-

-

-THE STEREOSCOPE SIMPLIFIED.

-

-When we look at any round object, first with one eye, and then with

-the other, we discover that with the right eye we see most of the

-right-hand side of the object, and with the left eye most of the

-left-hand side. These two images are combined, and we see an object

-which we know to be round.

-

-This is illustrated by the _Stereoscope_, which consists of two mirrors

-placed each at an angle of 45 deg., or of two semi-lenses turned with

-their curved sides towards each other. To view its phenomena two

-pictures are obtained by the camera on photographic paper of any object

-in two positions, corresponding with the conditions of viewing it with

-the two eyes. By the mirrors on the lenses these dissimilar pictures

-are combined within the eye, and the vision of an actually solid object

-is produced from the pictures represented on a plane surface. Hence the

-name of the instrument, which signifies _Solid I see_.--_Hunt’s Poetry

-of Science._

-

-

-PHOTO-GALVANIC ENGRAVING.

-

-That which was the chief aid of Niepce in the humblest dawn of the

-art, viz. to transform the photographic plate into a surface capable

-of being printed, is in the above process done by the coöperation of

-Electricity with Photography. This invention of M. Pretsch, of Vienna,

-differs from all other attempts for the same purpose in not operating

-upon the photographic tablet itself, and by discarding the usual means

-of varnishes and bitings-in. The process is simply this: A glass tablet

-is coated with gelatine diluted till it forms a jelly, and containing

-bi-chromate of potash, nitrate of silver, and iodide of potassium. Upon

-this, when dry, is placed face downwards a paper positive, through

-which the light, being allowed to fall, leaves upon the gelatine a

-representation of the print. It is then soaked in water; and while

-the parts acted upon by the light are comparatively unaffected by the

-fluid, the remainder of the jelly swells, and rising above the general

-surface, gives a picture in relief, resembling an ordinary engraving

-upon wood. Of this intaglio a cast is now taken in gutta-percha, to

-which the electro process in copper being applied, a plate or matrix is

-produced, bearing on it an exact repetition of the original positive

-picture. All that now remains to be done is to repeat the electro

-process; and the result is a copper-plate in the necessary relievo, of

-which it has been said nature furnished the materials and science the

-artist, the inferior workman being only needed to roll it through the

-press.--_Quarterly Review_, No. 202.

-

-

-SCIENCE OF THE SOAP-BUBBLE.

-

-Few of the minor ingenuities of mankind have amused so many individuals

-as the blowing of bubbles with soap-lather from the bowl of a

-tobacco-pipe; yet how few who in childhood’s careless hours have thus

-amused themselves, have in after-life become acquainted with the

-beautiful phenomena of light which the soap-bubble will enable us to

-illustrate!

-

-Usually the bubble is formed within the bowl of a tobacco-pipe, and

-so inflated by blowing through the stem. It is also produced by

-introducing a capillary tube under the surface of soapy water, and so

-raising a bubble, which may be inflated to any convenient size. It is

-then guarded with a glass cover, to prevent its bursting by currents of

-air, evaporation, and other causes.

-

-When the bubble is first blown, its form is elliptical, into which it

-is drawn by its gravity being resisted; but the instant it is detached

-from the pipe, and allowed to float in air, it becomes a perfect

-sphere, since the air within presses equally in all directions. There

-is also a strong cohesive attraction in the particles of soap and

-water, after having been forcibly distended; and as a sphere or globe

-possesses less surface than any other figure of equal capacity, it is

-of all forms the best adapted to the closest approximation of the

-particles of soap and water, which is another reason why the bubble

-is globular. The film of which the bubble consists is inconceivably

-thin (not exceeding the two-millionth part of an inch); and by the

-evaporation from its surface, the contraction and expansion of the air

-within, and the tendency of the soap-lather to gravitate towards the

-lower part of the bubble, and consequently to render the upper part

-still thinner, it follows that the bubble lasts but a few seconds. If,

-however, it were blown in a glass vessel, and the latter immediately

-closed, it might remain for some time; Dr. Paris thus preserved a

-bubble for a considerable period.

-

-Dr. Hooke, by means of the coloured rings upon the soap-bubble, studied

-the curious subject of the colours of thin plates, and its application

-to explain the colours of natural bodies. Various phenomena were also

-discovered by Newton, who thus did not disdain to make a soap-bubble

-the object of his study. The colours which are reflected from the upper

-surface of the bubble are caused by the decomposition of the light

-which falls upon it; and the range of the phenomena is alike extensive

-and beautiful.[15]

-

-Newton (says Sir D. Brewster), having covered the soap-bubble with a

-glass shade, saw its colours emerge in regular order, like so many

-concentric rings encompassing the top of it. As the bubble grew thinner

-by the continual subsidence of the water, the rings dilated slowly,

-and overspread the whole of it, descending to the bottom, where they

-vanished successively. When the colours had all emerged from the top,

-there arose in the centre of the rings a small round black spot,

-dilating it to more than half an inch in breadth till the bubble

-burst. Upon examining the rings between the object-glasses, Newton

-found that when they were only _eight_ or _nine_ in number, more than

-_forty_ could be seen by viewing them through a prism; and even when

-the plate of air seemed all over uniformly white, multitudes of rings

-were disclosed by the prism. By means of these observations Newton was

-enabled to form his _Scale of Colours_, of great value in all optical

-researches.

-

-Dr. Reade has thus produced a permanent soap-bubble:

-

-  Put into a six-ounce phial two ounces of distilled water, and set

-  the phial in a vessel of water boiling on the fire. The water in

-  the phial will soon boil, and steam will issue from its mouth,

-  expelling the whole of the atmospheric air from within. Then throw

-  in a piece of soap about the size of a small pea, cork the phial,

-  and at the same instant remove it and the vessel from the fire.

-  Then press the cork farther into the neck of the phial, and cover

-  it thickly with sealing-wax; and when the contents are cold, a

-  perfect vacuum will be formed within the bottle,--much better,

-  indeed, than can be produced by the best-constructed air-pump.

-

-  To form a bubble, hold the bottle horizontally in both hands, and

-  give it a sudden upward motion, which will throw the liquid into a

-  wave, whose crest touching the upper interior surface of the phial,

-  the tenacity of the liquid will cause a film to be retained all

-  round the phial. Next place the phial on its bottom; when the film

-  will form a section of the cylinder, being nearly but never quite

-  horizontal. The film will be now colourless, since it reflects all

-  the light which falls upon it. By remaining at rest for a minute or

-  two, minute currents of lather will descend by their gravitating

-  force down the inclined plane formed by the film, the upper part of

-  which thus becomes drained to the necessary thinness; and this is

-  the part to be observed.

-

-Several concentric segments of coloured rings are produced; the

-colours, beginning from the top, being as follows:

-

-    _1st order_: Black, white, yellow, orange, red.

-    _2d order_: Purple, blue, white, yellow, red.

-    _3d order_: Purple, blue, green, yellowish-green, white, red.

-    _4th order_: Purple, blue, green, white, red.

-    _5th order_: Greenish-blue, very pale red.

-    _6th order_: Greenish-blue, pink.

-    _7th order_: Greenish-blue, pink.

-

-As the segments advance they get broader, while the film becomes

-thinner and thinner. The several orders disappear upwards as the film

-becomes too thin to reflect their colours, until the first order alone

-remains, occupying the whole surface of the film. Of this order the

-red disappears first, then the orange, and lastly the yellow. The film

-is now divided by a line into two nearly equal portions, one black and

-the other white. This remains for some time; at length the film becomes

-too thin to hold together, and then vanishes. The colours are not faint

-and imperfect, but well defined, glowing with gorgeous hues, or melting

-into tints so exquisite as to have no rival through the whole circle

-of the arts. We quote these details from Mr. Tomlinson’s excellent

-_Student’s Manual of Natural Philosophy_.

-

-  We find the following anecdote related of Newton at the above

-  period. When Sir Isaac changed his residence, and went to live in

-  St. Martin’s Street, Leicester Square, his next-door neighbour was

-  a widow lady, who was much puzzled by the little she observed of

-  the habits of the philosopher. A Fellow of the Royal Society called

-  upon her one day, when, among her domestic news, she mentioned that

-  some one had come to reside in the adjoining house who, she felt

-  certain, was a poor crazy gentleman, “because,” she continued,

-  “he diverts himself in the oddest way imaginable. Every morning,

-  when the sun shines so brightly that we are obliged to draw the

-  window-blinds, he takes his seat on a little stool before a tub

-  of soapsuds, and occupies himself for hours blowing soap-bubbles

-  through a common clay-pipe, which bubbles he intently watches

-  floating about till they burst. He is doubtless,” she added, “now

-  at his favourite amusement, for it is a fine day; do come and look

-  at him.” The gentleman smiled, and they went upstairs; when, after

-  looking through the staircase-window into the adjoining court-yard,

-  he turned and said: “My dear madam, the person whom you suppose

-  to be a poor lunatic is no other than the great Sir Isaac Newton

-  studying the refraction of light upon thin plates; a phenomenon

-  which is beautifully exhibited on the surface of a common

-  soap-bubble.”

-

-

-LIGHT FROM QUARTZ.

-

-Among natural phenomena (says Sir David Brewster) illustrative of the

-colours of thin plates, we find none more remarkable than one exhibited

-by the fracture of a large crystal of quartz of a smoky colour, and

-about two and a quarter inches in diameter. The surface of fracture,

-in place of being a face or cleavage, or irregularly conchoidal, as we

-have sometimes seen it, was filamentous, like a surface of velvet, and

-consisted of short fibres, so small as to be incapable of reflecting

-light. Their size could not have been greater than the third of the

-millionth part of an inch, or one-fourth of the thinnest part of the

-soap-bubble when it exhibits the black spot where it bursts.

-

-

-CAN THE CAT SEE IN THE DARK?

-

-No, in all probability, says the reader; but the opposite popular

-belief is supported by eminent naturalists.

-

-  Buffon says: “The eyes of the cat shine in the dark somewhat like

-  diamonds, which throw out during the night the light with which

-  they were in a manner impregnated during the day.”

-

-  Valmont de Bamare says: “The pupil of the cat is during the night

-  still deeply imbued with the light of the day;” and again, “the

-  eyes of the cat are during the night so imbued with light that they

-  then appear very shining and luminous.”

-

-  Spallanzani says: “The eyes of cats, polecats, and several other

-  animals, shine in the dark like two small tapers;” and he adds that

-  this light is phosphoric.

-

-  Treviranus says: “The eyes of the cat _shine where no rays of

-  light penetrate_; and the light must in many, if not in all, cases

-  proceed from the eye itself.”

-

-Now, that the eyes of the cat do shine in the dark is to a certain

-extent true: but we have to inquire whether by _dark_ is meant the

-entire absence of light; and it will be found that the solution of this

-question will dispose of several assertions and theories which have for

-centuries perplexed the subject.

-

-Dr. Karl Ludwig Esser has published in Karsten’s Archives the results

-of an experimental inquiry on the luminous appearance of the eyes of

-the cat and other animals, carefully distinguishing such as evolve

-light from those which only reflect it. Having brought a cat into a

-half-darkened room, he observed from a certain direction that the cat’s

-eyes, when _opposite the window_, sparkled brilliantly; but in other

-positions the light suddenly vanished. On causing the cat to be held

-so as to exhibit the light, and then gradually darkening the room, the

-light disappeared by the time the room was made quite dark.

-

-In another experiment, a cat was placed opposite the window in a

-darkened room. A few rays were permitted to enter, and by adjusting the

-light, one or both of the cat’s eyes were made to shine. In proportion

-as the pupil was dilated, the eyes were brilliant. By suddenly

-admitting a strong glare of light into the room, the pupil contracted;

-and then suddenly darkening the room, the eye exhibited a small round

-luminous point, which enlarged as the pupil dilated.

-

-The eyes of the cat sparkle most when the animal is in a lurking

-position, or in a state of irritation. Indeed, the eyes of all animals,

-as well as of man, appear brighter when in rage than in a quiescent

-state, which Collins has commemorated in his Ode on the Passions:

-

-    “Next Anger rushed, his eyes on fire.”

-

-This brilliancy is said to arise from an increased secretion of the

-lachrymal fluid on the surface of the eye, by which the reflection of

-the light is increased. Dr. Esser, in places absolutely dark, never

-discovered the slightest trace of light in the eye of the cat; and he

-has no doubt that in all cases where cats’ eyes have been seen to shine

-in dark places, such as a cellar, light penetrated through some window

-or aperture, and fell upon the eyes of the animal as it turned towards

-the opening, while the observer was favourably situated to obtain a

-view of the reflection.

-

-To prove more clearly that this light does not depend upon the will of

-the animal, nor upon its angry passions, experiments were made upon

-the head of a dead cat. The sun’s rays were admitted through a small

-aperture; and falling immediately upon the eyes, caused them to glow

-with a beautiful green light more vivid even than in the case of a

-living animal, on account of the increased dilatation of the pupil.

-It was also remarked that black and fox-coloured cats gave a brighter

-light than gray and white cats.

-

-To ascertain the cause of this luminous appearance Dr. Esser dissected

-the eyes of cats, and exposed them to a small regulated amount of light

-after having removed different portions. The light was not diminished

-by the removal of the cornea, but only changed in colour. The light

-still continued after the iris was displaced; but on taking away the

-crystalline lens it greatly diminished both in intensity and colour.

-Dr. Esser then conjectured that the tapetum in the hinder part of the

-eye must form a spot which caused the reflection of the incident

-rays of light, and thus produce the shining; and this appeared more

-probable as the light of the eye now seemed to emanate from a single

-spot. Having taken away the vitreous humour, Dr. Esser observed that

-the entire want of the pigment in the hinder part of the choroid coat,

-where the optic nerve enters, formed a greenish, silver-coloured,

-changeable oblong spot, which was not symmetrical, but surrounded the

-optic nerve so that the greater part was above and only the smaller

-part below it; wherefore the greater part lay beyond the axis of

-vision. It is this spot, therefore, that produces the reflection of the

-incident rays of light, and beyond all doubt, according to its tint,

-contributes to the different colouring of the light.

-

-It may be as well to explain that the interior of the eye is coated

-with a black pigment, which has the same effect as the black colour

-given to the inner surface of optical instruments: it absorbs any

-rays of light that may be reflected within the eye, and prevents

-them from being thrown again upon the retina so as to interfere with

-the distinctness of the images formed upon it. The retina is very

-transparent; and if the surface behind it, instead of being of a dark

-colour, were capable of reflecting light, the luminous rays which had

-already acted on the retina would be reflected back again through it,

-and not only dazzle from excess of light, but also confuse and render

-indistinct the images formed on the retina. Now in the case of the cat

-this black pigment, or a portion of it, is wanting; and those parts of

-the eye from which it is absent, having either a white or a metallic

-lustre, are called the tapetum. The smallest portion of light entering

-from it is reflected as by a concave mirror; and hence it is that the

-eyes of animals provided with this structure are luminous in a very

-faint light.

-

-These experiments and observations show that the shining of the eyes

-of the cat does not arise from a phosphoric light, but only from a

-reflected light; that consequently it is not an effect of the will of

-the animal, or of violent passions; that their shining does not appear

-in absolute darkness; and that it cannot enable the animal to move

-securely in the dark.

-

-It has been proved by experiment that there exists a set of rays of

-light of far higher refrangibility than those seen in the ordinary

-Newtonian spectrum. Mr. Hunt considers it probable that these highly

-refrangible rays, although under ordinary circumstances invisible

-to the human eye, may be adapted to produce the necessary degree

-of excitement upon which vision depends in the optic nerves of the

-night-roaming animals. The bat, the owl, and the cat may see in the

-gloom of the night by the aid of rays which are invisible to, or

-inactive on, the eyes of man or those animals which require the light

-of day for perfect vision.

-

-

-

-

-Astronomy.

-

-

-THE GREAT TRUTHS OF ASTRONOMY.

-

-The difficulty of understanding these marvellous truths has been

-glanced at by an old divine (see _Things not generally Known_, p.

-1); but the rarity of their full comprehension by those unskilled in

-mathematical science is more powerfully urged by Lord Brougham in these

-cogent terms:

-

-  Satisfying himself of the laws which regulate the mutual actions

-  of the planetary bodies, the mathematician can convince himself of

-  a truth yet more sublime than Newton’s discovery of gravitation,

-  though flowing from it; and must yield his assent to the marvellous

-  position, that all the irregularities occasioned in the system

-  of the universe by the mutual attraction of its members are

-  periodical, and subject to an eternal law, which prevents them from

-  ever exceeding a stated amount, and secures through all time the

-  balanced structure of a universe composed of bodies whose mighty

-  bulk and prodigious swiftness of motion mock the utmost efforts

-  of the human imagination. All these truths are to the skilful

-  mathematician as thoroughly known, and their evidence is as clear,

-  as the simplest proposition of arithmetic to common understandings.

-  But how few are those who thus know and comprehend them! Of all

-  the millions that thoroughly believe these truths, certainly not a

-  thousand individuals are capable of following even any considerable

-  portion of the demonstrations upon which they rest; and probably

-  not a hundred now living have ever gone through the whole steps

-  of these demonstrations.--_Dissertations on Subjects of Science

-  connected with Natural Theology_, vol. ii.

-

-Sir David Brewster thus impressively illustrates the same subject:

-

-  Minds fitted and prepared for this species of inquiry are

-  capable of appreciating the great variety of evidence by

-  which the truths of the planetary system are established; but

-  thousands of individuals, and many who are highly distinguished

-  in other branches of knowledge, are incapable of understanding

-  such researches, and view with a sceptical eye the great and

-  irrefragable truths of astronomy.

-

-  That the sun is stationary in the centre of our system; that

-  the earth moves round the sun, and round its own axis; that

-  the diameter of the earth is 8000 miles, and that of the sun

-  _one hundred and ten times as great_; that the earth’s orbit is

-  190,000,000 of miles in breadth; and that if this immense space

-  were filled with light, it would appear only like a luminous point

-  at the nearest fixed star,--are positions absolutely unintelligible

-  and incredible to all who have not carefully studied the subject.

-  To millions of our species, then, the great Book of Nature is

-  absolutely sealed; though it is in the power of all to unfold its

-  pages, and to peruse those glowing passages which proclaim the

-  power and wisdom of its Author.

-

-

-ASTRONOMY AND DATES ON MONUMENTS.

-

-Astronomy is a useful aid in discovering the Dates of ancient

-Monuments. Thus, on the ceiling of a portico among the ruins of

-Tentyris are the twelve signs of the Zodiac, placed according to the

-apparent motion of the sun. According to this Zodiac, the summer

-solstice is in Leo; from which it is easy to compute, by the precession

-of the equinoxes of 50″·1 annually, that the Zodiac of Tentyris must

-have been made 4000 years ago.

-

-Mrs. Somerville relates that she once witnessed the ascertainment of

-the date of a Papyrus by means of astronomy. The manuscript was found

-in Egypt, in a mummy-case; and its antiquity was determined by the

-configuration of the heavens at the time of its construction. It proved

-to be a horoscope of the time of Ptolemy.

-

-

-“THE CRYSTAL VAULT OF HEAVEN.”

-

-This poetic designation dates back as far as the early period of

-Anaximenes; but the first clearly defined signification of the idea on

-which the term is based occurs in Empedocles. This philosopher regarded

-the heaven of the fixed stars as a solid mass, formed from the ether

-which had been rendered crystalline by the action of fire.

-

-In the Middle Ages, the fathers of the Church believed the firmament to

-consist of from seven to ten glassy strata, incasing each other like

-the different coatings of an onion. This supposition still keeps its

-ground in some of the monasteries of southern Europe, where Humboldt

-was greatly surprised to hear a venerable prelate express an opinion in

-reference to the fall of aerolites at Aigle, that the bodies we called

-meteoric stones with vitrified crusts were not portions of the fallen

-stone itself, but simply fragments of the crystal vault shattered by it

-in its fall.

-

-Empedocles maintained that the fixed stars were riveted to the

-crystal heavens; but that the planets were free and unconstrained.

-It is difficult to conceive how, according to Plato in the _Timæus_,

-the fixed stars, riveted as they are to solid spheres, could rotate

-independently.

-

-Among the ancient views, it may be mentioned that the equal distance

-at which the stars remained, while the whole vault of heaven seemed to

-move from east to west, had led to the idea of a firmament and a solid

-crystal sphere, in which Anaximenes (who was probably not much later

-than Pythagoras) had conjectured that the stars were riveted like nails.

-

-

-MUSIC OF THE SPHERES.

-

-The Pythagoreans, in applying their theory of numbers to the

-geometrical consideration of the five regular bodies, to the musical

-intervals of tone which determine a word and form different kinds

-of sounds, extended it even to the system of the universe itself;

-supposing that the moving, and, as it were, vibrating planets, exciting

-sound-waves, must produce a _spheral music_, according to the harmonic

-relations of their intervals of space. “This music,” they add, “would

-be perceived by the human ear, if it was not rendered insensible by

-extreme familiarity, as it is perpetual, and men are accustomed to it

-from childhood.”

-

-  The Pythagoreans affirm, in order to justify the reality of the

-  tones produced by the revolution of the spheres, that hearing takes

-  place only where there is an alternation of sound and silence. The

-  inaudibility of the spheral music is also accounted for by its

-  overpowering the senses. Aristotle himself calls the Pythagorean

-  tone-myth pleasing and ingenious, but untrue.

-

-Plato attempted to illustrate the tones of the universe in an

-agreeable picture, by attributing to each of the planetary spheres a

-syren, who, supported by the stern daughters of Necessity, the three

-Fates, maintain the eternal revolution of the world’s axis. Mention

-is constantly made of the harmony of the spheres, though generally

-reproachfully, throughout the writings of Christian antiquity and the

-Middle Ages, from Basil the Great to Thomas Aquinas and Petrus Alliacus.

-

-At the close of the sixteenth century, Kepler revived these musical

-ideas, and sought to trace out the analogies between the relations of

-tone and the distances of the planets; and Tycho Brahe was of opinion

-that the revolving conical bodies were capable of vibrating the

-celestial air (what we now call “resisting medium”) so as to produce

-tones. Yet Kepler, although he had talked of Venus and the Earth

-sounding sharp in aphelion and flat in perihelion, and the highest tone

-of Jupiter and that of Venus coinciding in flat accord, positively

-declared there to be “no such things as sounds among the heavenly

-bodies, nor is their motion so turbulent as to elicit noise from the

-attrition of the celestial air.” (See _Things not generally Known_, p.

-44.)

-

-

-“MORE WORLDS THAN ONE.”

-

-Although this opinion was maintained incidentally by various writers

-both on astronomy[16] and natural religion, yet M. Fontenelle was the

-first individual who wrote a treatise on the _Plurality of Worlds_,

-which appeared in 1685, the year before the publication of Newton’s

-_Principia_. Fontenelle’s work consists of five chapters: 1. The earth

-is a planet which turns round its axis, and also round the sun. 2. The

-moon is a habitable world. 3. Particulars concerning the world in the

-moon, and that the other planets are also inhabited. 4. Particulars of

-the worlds of Venus, Mercury, Mars, Jupiter, and Saturn. 5. The fixed

-stars are as many suns, each of which illuminates a world. In a future

-edition, 1719, Fontenelle added, 6. New thoughts which confirm those in

-the preceding conversations, and the latest discoveries which have been

-made in the heavens. The next work on the subject was the _Theory of

-the Universe, or Conjectures concerning the Celestial Bodies and their

-Inhabitants_, 1698, by Christian Huygens, the contemporary of Newton.

-

-The doctrine is maintained by almost all the distinguished astronomers

-and writers who have flourished since the true figure of the earth was

-determined. Giordano Bruna of Nola, Kepler, and Tycho Brahe, believed

-in it; and Cardinal Cusa and Bruno, before the discovery of binary

-systems among the stars, believed also that the stars were inhabited.

-Sir Isaac Newton likewise adopted the belief; and Dr. Bentley, Master

-of Trinity College, Cambridge, in his eighth sermon on the Confutation

-of Atheism from the origin and frame of the world, has ably maintained

-the same doctrine. In our own day we may number among its supporters

-the distinguished names of the Marquis de la Place, Sir William and

-Sir John Herschel, Dr. Chalmers, Isaac Taylor, and M. Arago. Dr.

-Chalmers maintains the doctrine in his _Astronomical Discourses_, which

-one Alexander Maxwell (who did not believe in the grand truths of

-astronomy) attempted to controvert, in 1820, in a chapter of a volume

-entitled _Plurality of Worlds_.

-

-Next appeared _Of a Plurality of Worlds_, attributed to the Rev. Dr.

-Whewell, Master of Trinity College, Cambridge; urging the theological

-not less than the scientific reasons for believing in the old tradition

-of a single world, and maintaining that “the earth is really the

-largest planetary body in the solar system,--its domestic hearth,

-and the only world in the universe.” “I do not pretend,” says Dr.

-Whewell, “to disprove the plurality of worlds; but I ask in vain for

-any argument which makes the doctrine probable.” “It is too remote

-from knowledge to be either proved or disproved.” Sir David Brewster

-has replied to Dr. Whewell’s Essay, in _More Worlds than One, the

-Creed of the Philosopher and the Hope of the Christian_, emphatically

-maintaining that analogy strongly countenances the idea of all the

-solar planets, if not all worlds in the universe, being peopled with

-creatures not dissimilar in being and nature to the inhabitants

-of the earth. This view is supported in _Scientific Certainties of

-Planetary Life_, by T. C. Simon, who well treats one point of the

-argument--that mere distance of the planets from the central sun

-does not determine the condition as to light and heat, but that the

-density of the ethereal medium enters largely into the calculation. Mr.

-Simon’s general conclusion is, that “neither on account of deficient

-or excessive heat, nor with regard to the density of the materials,

-nor with regard to the force of gravity on the surface, is there the

-slightest pretext for supposing that all the planets of our system

-are not inhabited by intellectual creatures with animal bodies like

-ourselves,--moral beings, who know and love their great Maker, and

-who wait, like the rest of His creation, upon His providence and upon

-His care.” One of the leading points of Dr. Whewell’s Essay is, that

-we should not elevate the conjectures of analogy into the rank of

-scientific certainties; and that “the force of all the presumptions

-drawn from physical reasoning for the opinion of planets and stars

-being either inhabited or uninhabited is so small, that the belief of

-all thoughtful persons on this subject will be determined by moral,

-metaphysical, and theological considerations.”

-

-

-WORLDS TO COME--ABODES OF THE BLEST.

-

-Sir David Brewster, in his eloquent advocacy of the doctrine of “more

-worlds than one,” thus argues for their peopling:

-

-  Man, in his future state of existence, is to consist, as at

-  present, of a spiritual nature residing in a corporeal frame. He

-  must live, therefore, upon a material planet, subject to all the

-  laws of matter, and performing functions for which a material body

-  is indispensable. We must consequently find for the race of Adam,

-  if not races that may have preceded him, a material home upon which

-  they may reside, or by which they may travel, by means unknown to

-  us, to other localities in the universe. At the present hour, the

-  inhabitants of the earth are nearly _a thousand millions_; and

-  by whatever process we may compute the numbers that have existed

-  before the present generation, and estimate those that are yet to

-  inherit the earth, we shall obtain a population which the habitable

-  parts of our globe could not possibly accommodate. If there is not

-  room, then, on our earth for the millions of millions of beings who

-  have lived and died upon its surface, and who may yet live and die

-  during the period fixed for its occupation by man, we can scarcely

-  doubt that their future abode must be on some of the primary or

-  secondary planets of the solar system, whose inhabitants have

-  ceased to exist like those on the earth, or upon planets in our own

-  or in other systems which have been in a state of preparation, as

-  our earth was, for the advent of intellectual life.

-

-

-“GAUGING THE HEAVENS.”

-

-Sir William Herschel, in 1785, conceived the happy idea of counting

-the number of stars which passed at different heights and in various

-directions over the field of view, of fifteen minutes in diameter,

-of his twenty-feet reflecting telescope. The field of view each time

-embraced only 1/833000th of the whole heavens; and it would therefore

-require, according to Struve, eighty-three years to gauge the whole

-sphere by a similar process.

-

-

-VELOCITY OF THE SOLAR SYSTEM.

-

-M. F. W. G. Struve gives as the splendid result of the united studies

-of MM. Argelander, O. Struve, and Peters, grounded on observations

-made at the three Russian observatories of Dorpat, Abo, and Pulkowa,

-“that the velocity of the motion of the solar system in space is such

-that the sun, with all the bodies which depend upon it, advances

-annually towards the constellation Hercules[17] 1·623 times the radius

-of the earth’s orbit, or 33,550,000 geographical miles. The possible

-error of this last number amounts to 1,733,000 geographical miles, or

-to a _seventh_ of the whole value. We may, then, wager 400,000 to 1

-that the sun has a proper progressive motion, and 1 to 1 that it is

-comprised between the limits of thirty-eight and twenty-nine millions

-of geographical miles.”

-

-  That is, taking 95,000,000 of English miles as the mean radius of

-  the Earth’s orbit, we have 95 × 1·623 = 154·185 millions of miles;

-  and consequently,

-

-                                          English Miles.

-    The velocity of the Solar System      154,185,000 in the year.

-           ”         ”                        422,424 in a day.

-           ”         ”                         17,601 in an hour.

-           ”         ”                            293 in a minute.

-           ”         ”                             57 in a second.

-

-  The Sun and all his planets, primary and secondary, are therefore

-  now in rapid motion round an invisible focus. To that now dark and

-  mysterious centre, from which no ray, however feeble, shines, we

-  may in another age point our telescopes, detecting perchance the

-  great luminary which controls our system and bounds its path: into

-  that vast orbit man, during the whole cycle of his race, may never

-  be allowed to round.--_North-British Review_, No. 16.

-

-

-NATURE OF THE SUN.

-

-M. Arago has found, by experiments with the polariscope, that the light

-of gaseous bodies is natural light when it issues from the burning

-surface; although this circumstance does not prevent its subsequent

-complete polarisation, if subjected to suitable reflections or

-refractions. Hence we obtain _a most simple method of discovering

-the nature of the sun_ at a distance of forty millions of leagues.

-For if the light emanating from the margin of the sun, and radiating

-from the solar substance _at an acute angle_, reach us without having

-experienced any sensible reflections or refractions in its passage

-to the earth, and if it offer traces of polarisation, the sun must

-be _a solid or a liquid body_. But if, on the contrary, the light

-emanating from the sun’s margin give no indications of polarisation,

-the _incandescent_ portion of the sun must be _gaseous_. It is by means

-of such a methodical sequence of observations that we may acquire

-exact ideas regarding the physical constitution of the sun.--_Note to

-Humboldt’s Cosmos_, vol. iii.

-

-

-STRUCTURE OF THE LUMINOUS DISC OF THE SUN.

-

-The extraordinary structure of the _fully luminous_ Disc of the Sun, as

-seen through Sir James South’s great achromatic, in a drawing made by

-Mr. Gwilt, resembles compressed curd, or white almond-soap, or a mass

-of asbestos fibres, lying in a _quaquaversus_ direction, and compressed

-into a solid mass. There can be no illusion in this phenomenon; it

-is seen by every person with good vision, and on every part of the

-sun’s luminous surface or envelope, which is thus shown to be not a

-_flame_, but a soft solid or thick fluid, maintained in an incandescent

-state by subjacent heat, capable of being disturbed by differences of

-temperature, and broken up as we see it when the sun is covered with

-spots or openings in the luminous matter.--_North-British Review_, No.

-16.

-

-  Copernicus named the sun the lantern of the world (_lucerna

-  mundi_); and Theon of Smyrna called it the heart of the universe.

-  The mass of the sun is, according to Encke’s calculation of

-  Sabine’s pendulum formula, 359,551 times that of the earth, or

-  355,499 times that of the earth and moon together; whence the

-  density of the sun is only about ¼ (or more accurately 0·252) that

-  of the earth. The volume of the sun is 600 times greater, and its

-  mass, according to Galle, 738 times greater, than that of all the

-  planets combined. It may assist the mind in conceiving a sensuous

-  image of the magnitude of the sun, if we remember that if the solar

-  sphere were entirely hollowed out, and the earth placed in its

-  centre, there would still be room enough for the moon to describe

-  its orbit, even if the radius of the latter were increased 160,000

-  geographical miles. A railway-engine, moving at the rate of thirty

-  miles an hour, would require 360 years to travel from the earth to

-  the sun. The diameter of the sun is rather more than one hundred

-  and eleven times the diameter of the earth. Therefore the volume or

-  bulk of the sun must be nearly _one million four hundred thousand_

-  times that of the earth. Lastly, if all the bodies composing the

-  solar system were formed into one globe, it would be only about the

-  five-hundredth part of the size of the sun.

-

-

-GREAT SIZE OF THE SUN ON THE HORIZON EXPLAINED.

-

-The dilated size (generally) of the Sun or Moon, when seen near the

-horizon, beyond what they appear to have when high up in the sky, has

-nothing to do with refraction. It is an illusion of the judgment,

-arising from the terrestrial objects interposed, or placed in close

-comparison with them. In that situation we view and judge of them

-as we do of terrestrial objects--in detail, and with an acquired

-attention to parts. Aloft we have no association to guide us, and their

-insulation in the expanse of the sky leads us rather to undervalue

-than to over-rate their apparent magnitudes. Actual measurement with

-a proper instrument corrects our error, without, however, dispelling

-our illusion. By this we learn that the sun, when just on the horizon,

-subtends at our eyes almost exactly the same, and the moon a materially

-_less_, angle than when seen at a greater altitude in the sky, owing to

-its greater distance from us in the former situation as compared with

-the latter.--_Sir John Herschel’s Outlines._

-

-

-TRANSLATORY MOTION OF THE SUN.

-

-This phenomenon is the progressive motion of the centre of gravity of

-the whole solar system in universal space. Its velocity, according

-to Bessel, is probably four millions of miles daily, in a _relative_

-velocity to that of 61 Cygni of at least 3,336,000 miles, or more than

-double the velocity of the revolution of the earth in her orbit round

-the sun. This change of the entire solar system would remain unknown

-to us, if the admirable exactness of our astronomical instruments of

-measurement, and the advancement recently made in the art of observing,

-did not cause our progress towards remote stars to be perceptible,

-like an approximation to the objects of a distant shore in apparent

-motion. The proper motion of the star 61 Cygni, for instance, is so

-considerable, that it has amounted to a whole degree in the course of

-700 years.--_Humboldt’s Cosmos_, vol. i.

-

-

-THE SUN’S LIGHT COMPARED WITH TERRESTRIAL LIGHTS.

-

-Mr. Ponton has by means of a simple monochromatic photometer

-ascertained that a small surface, illuminated by mean solar light, is

-444 times brighter than when it is illuminated by a moderator lamp, and

-1560 times brighter than when it is illuminated by a wax-candle (short

-six in the lb.)--the artificial light being in both instances placed at

-two inches’ distance from the illuminated surface. And three electric

-lights, each equal to 520 wax-candles, will render a small surface as

-bright as when it is illuminated by mean sunshine.

-

-It is thence inferred, that a stratum occupying the entire surface of

-the sphere of which the earth’s distance from the sun is the radius,

-and consisting of three layers of flame, each 1/1000th of an inch

-in thickness, each possessing a brightness equal to that of such an

-electric light, and all three embraced within a thickness of 1/40th of

-an inch, would give an amount of illumination equal in quantity and

-intensity to that of the sun at the distance of 95 millions of miles

-from his centre.

-

-And were such a stratum transferred to the surface of the sun, where it

-would occupy 46,275 times less area, its thickness would be increased

-to 94 feet, and it would embrace 138,825 layers of flame, equal in

-brightness to the electric light; but the same effect might be produced

-by a stratum about nine miles in thickness, embracing 72 millions of

-layers, each having only a brightness equal to that of a wax-candle.[18]

-

-

-ACTINIC POWER OF THE SUN.

-

-Mr. J. J. Waterston, in 1857, made at Bombay some experiments on the

-photographic power of the sun’s direct light, to obtain data in an

-inquiry as to the possibility of measuring the diameter of the sun to

-a very minute fraction of a second, by combining photography with the

-principle of the electric telegraph; the first to measure the element

-space, the latter the element time. The result is that about 1/20000th

-of a second is sufficient exposure to the direct light of the sun to

-obtain a distinct mark on a sensitive collodion plate, when developed

-by the usual processes; and the duration of the sun’s full action on

-any one point is about 1/9000th of a second.

-

-M. Schatt, a young painter of Berlin, after 1500 experiments, succeeded

-in establishing a scale of all the shades of black which the action of

-the sun produces on photographic paper; so that by comparing the shade

-obtained at any given moment on a certain paper with that indicated on

-the scale, the exact force of the sun’s light may be determined.

-

-

-HEATING POWER OF THE SUN.

-

-All moving power has its origin in the rays of the sun. While

-Stephenson’s iron tubular railway-bridge over the Menai Straits, 400

-feet long, bends but half an inch under the heaviest pressure of a

-train, it will bend up an inch and a half from its usual horizontal

-line when the sun shines on it for some hours. The Bunker-Hill

-monument, near Boston, U.S., is higher in the evening than in the

-morning of a sunny day; the little sunbeams enter the pores of the

-stone like so many wedges, lifting it up.

-

-In winter, the Earth is nearer the Sun by about 1/30 than in summer;

-but the rays strike the northern hemisphere more obliquely in winter

-than the other half year.

-

-M. Pouillet has estimated, with singular ingenuity, from a series of

-observations made by himself, that the whole quantity of heat which the

-Earth receives annually from the Sun is such as would be sufficient to

-melt a stratum of ice covering the entire globe forty-six feet deep.

-

-By the action of the sun’s rays upon the earth, vegetables, animals,

-and man, are in their turn supported; the rays become likewise, as

-it were, a store of heat, and “the sources of those great deposits

-of dynamical efficiency which are laid up for human use in our coal

-strata” (_Herschel_).

-

-A remarkable instance of the power of the sun’s rays is recorded at

-Stonehouse Point, Devon, in the year 1828. To lay the foundation of a

-sea-wall the workmen had to descend in a diving-bell, which was fitted

-with convex glasses in the upper part, by which, on several occasions

-in clear weather, the sun’s rays were so concentrated as to burn the

-labourers’ clothes when opposed to the focal point, and this when the

-bell was twenty-five feet under the surface of the water!

-

-

-CAUSE OF DARK COLOUR OF THE SKIN.

-

-Darkness of complexion has been attributed to the sun’s power from the

-age of Solomon to this day,--“Look not upon me, because I am black,

-because the sun hath looked upon me:” and there cannot be a doubt

-that, to a certain degree, the opinion is well founded. The invisible

-rays in the solar beams, which change vegetable colour, and have been

-employed with such remarkable effect in the daguerreotype, act upon

-every substance on which they fall, producing mysterious and wonderful

-changes in their molecular state, man not excepted.--_Mrs. Somerville._

-

-

-EXTREME SOLAR HEAT.

-

-The fluctuation in the sun’s direct heating power amounts to 1/15th,

-which is too considerable a fraction of the whole intensity not

-to aggravate in a serious degree the sufferings of those who are

-exposed to it in thirsty deserts without shelter. The amount of these

-sufferings, in the interior of Australia for instance, are of the

-most frightful kind, and would seem far to exceed what have ever been

-undergone by travellers in the northern deserts of Africa. Thus

-Captain Sturt, in his account of his Australian exploration, says:

-“The ground was almost a molten surface; and if a match accidentally

-fell upon it, it immediately ignited.” Sir John Herschel has observed

-the temperature of the surface soil in South Africa as high as 159°

-Fahrenheit. An ordinary lucifer-match does not ignite when simply

-pressed upon a smooth surface at 212°; but _in the act of withdrawing

-it_ it takes fire, and the slightest friction upon such a surface of

-course ignites it.

-

-

-HOW DR. WOLLASTON COMPARED THE LIGHT OF THE SUN AND THE FIXED STARS.

-

-In order to compare the Light of the Sun with that of a Star, Dr.

-Wollaston took as an intermediate object of comparison the light of a

-candle reflected from a bulb about a quarter of an inch in diameter,

-filled with quicksilver; and seen by one eye through a lens of two

-inches focus, at the same time that the star on the sun’s image,

-_placed at a proper distance_, was viewed by the other eye through a

-telescope. The mean of various trials seemed to show that the light

-of Sirius is equal to that of the sun seen in a glass bulb 1/10th of

-an inch in diameter, at the distance of 210 feet; or that they are in

-the proportion of one to ten thousand millions: but as nearly one half

-of this light is lost by reflection, the real proportion between the

-light from Sirius and the sun is not greater than that of one to twenty

-thousand millions.

-

-

-“THE SUN DARKENED.”

-

-Humboldt selects the following example from historical records as to

-the occurrence of a sudden decrease in the light of the Sun:

-

-  A.D. 33, the year of the Crucifixion. “Now from the sixth hour

-  there was darkness over all the land till the ninth hour” (_St.

-  Matthew_ xxvii. 45). According to _St. Luke_ (xxiii. 45), “the

-  sun was darkened.” In order to explain and corroborate these

-  narrations, Eusebius brings forward an eclipse of the sun in the

-  202d Olympiad, which had been noticed by the chronicler Phlegon

-  of Tralles (_Ideler_, _Handbuch der Mathem. Chronologie_, Bd. ii.

-  p. 417). Wurn, however, has shown that the eclipse which occurred

-  during this Olympiad, and was visible over the whole of Asia

-  Minor, must have happened as early as the 24th of November 29 A.D.

-  The day of the Crucifixion corresponded with the Jewish Passover

-  (_Ideler_, Bd. i. pp. 515-520), on the 14th of the month Nisan, and

-  the Passover was always celebrated at the time of the _full moon_.

-  The sun cannot therefore have been darkened for three hours by the

-  moon. The Jesuit Scheiner thinks the decrease in the light might be

-  ascribed to the occurrence of large sun-spots.

-

-

-THE SUN AND TERRESTRIAL MAGNETISM.

-

-The important influence exerted by the Sun’s body, as a mass, upon

-Terrestrial Magnetism, is confirmed by Sabine in the ingenious

-observation, that the period at which the intensity of the magnetic

-force is greatest, and the direction of the needle most near to the

-vertical line, falls in both hemispheres between the months of October

-and February; that is to say, precisely at the time when the earth is

-nearest to the sun, and moves in its orbit with the greatest velocity.

-

-

-IS THE HEAT OF THE SUN DECREASING?

-

-The Heat of the Sun is dissipated and lost by radiation, and must

-be progressively diminished unless its thermal energy be supplied.

-According to the measurements of M. Pouillet, the quantity of heat

-given out by the sun in a year is equal to that which would be produced

-by the combustion of a stratum of coal seventeen miles in thickness;

-and if the sun’s capacity for heat be assumed equal to that of water,

-and the heat be supposed drawn uniformly from its entire mass, its

-temperature would thereby undergo a diminution of 20·4° Fahr. annually.

-On the other hand, there is a vast store of force in our system capable

-of conversion into heat. If, as is indicated by the small density of

-the sun, and by other circumstances, that body has not yet reached the

-condition of incompressibility, we have in the future approximation of

-its parts a fund of heat, probably quite large enough to supply the

-wants of the human family to the end of its sojourn here. It has been

-calculated that an amount of condensation which would diminish the

-diameter of the sun by only the ten-thousandth part, would suffice to

-restore the heat emitted in 2000 years.

-

-

-UNIVERSAL SUN-DIAL.

-

-Mr. Sharp, of Dublin, exhibited to the British Association in 1849 a

-Dial, consisting of a cylinder set to the day of the month, and then

-elevated to the latitude. A thin plane of metal, in the direction of

-its axis, is then turned by a milled head below it till the shadow is

-a minimum, when a dial on the top shows the hours by one hand, and the

-minutes by another, to the precision of about three minutes.

-

-

-LENGTH OF DAYS AT THE POLES.

-

-During the summer, in the northern hemisphere, places near the North

-Pole are in _continual sunlight_--the sun never sets to them; while

-during that time places near the South Pole never see the sun. When it

-is summer in the southern hemisphere, and the sun shines on the South

-Pole without setting, the North Pole is entirely deprived of his light.

-Indeed, at the Poles there is but _one day and one night_; for the sun

-shines for six months together on one Pole, and the other six months on

-the other Pole.

-

-

-HOW THE DISTANCE OF THE SUN IS ASCERTAINED BY THE YARD-MEASURE.

-

-Professor Airy, in his _Six Lectures on Astronomy_, gives a masterly

-analysis of a problem of considerable intricacy, viz. the determination

-of the parallax of the sun, and consequently of his distance, by

-observations of the transit of Venus, the connecting link between

-measures upon the earth’s surface and the dimensions of our system.

-The further step of investigating the parallax, and consequently the

-distance of the fixed stars (where that is practicable), is also

-elucidated; and the author, with evident satisfaction, thus sums up the

-several steps:

-

-  By means of a yard-measure, a base-line in a survey was measured;

-  from this, by the triangulations and computations of a survey,

-  an arc of meridian on the earth was measured; from this, with

-  proper observations with the zenith sector, the surveys being also

-  repeated on different parts of the earth, the earth’s form and

-  dimensions were ascertained; from these, and a previous independent

-  knowledge of the proportions of the distances of the earth and

-  other planets from the sun, with observations of the transit of

-  Venus, the sun’s distance is determined; and from this, with

-  observations leading to the parallax of the stars, the distance

-  of the stars is determined. And _every step in the process can be

-  distinctly referred to its basis, that is, the yard-measure_.

-

-

-HOW THE TIDES ARE PRODUCED BY THE SUN AND MOON.

-

-Each of these bodies excites, by its attraction upon the waters of the

-sea, two gigantic waves, which flow in the same direction round the

-world as the attracting bodies themselves apparently do. The two waves

-of the moon, on account of her greater nearness, are about 3½ times as

-large as those excited by the sun. One of these waves has its crest on

-the quarter of the earth’s surface which is turned towards the moon;

-the other is at the opposite side. Both these quarters possess the flow

-of the tide, while the regions which lie between have the ebb. Although

-in the open sea the height of the tide amounts to only about three

-feet, and only in certain narrow channels, where the moving water is

-squeezed together, rises to thirty feet, the might of the phenomenon

-is nevertheless manifest from the calculation of Bessel, according to

-which a quarter of the earth covered by the sea possesses during the

-flow of the tide about 25,000 cubic miles of water more than during the

-ebb; and that, therefore, such a mass of water must in 6¼ hours flow

-from one quarter of the earth to the other.--_Professor Helmholtz._

-

-

-SPOTS ON THE SUN.

-

-Sir John Herschel describes these phenomena, when watched from day to

-day, or even from hour to hour, as appearing to enlarge or contract,

-to change their forms, and at length disappear altogether, or to break

-out anew in parts of the surface where none were before. Occasionally

-they break up or divide into two or more. The scale on which their

-movements takes place is immense. A single second of angular measure,

-as seen from the earth, corresponds on the sun’s disc to 461 miles; and

-a circle of this diameter (containing therefore nearly 167,000 square

-miles) is the least space which can be distinctly discerned on the sun

-as a _visible area_. Spots have been observed, however, whose linear

-diameter has been upwards of 45,000 miles; and even, if some records

-are to be trusted, of very much greater extent. That such a spot should

-close up in six weeks time (for they seldom last much longer), its

-borders must approach at the rate of more than 1000 miles a-day.

-

-The same astronomer saw at the Cape of Good Hope, on the 29th March

-1837, a solar spot occupying an area of near _five square minutes_,

-equal to 3,780,000,000 square miles. “The black centre of the spot of

-May 25th, 1837 (not the tenth part of the preceding one), would have

-allowed the globe of our earth to drop through it, leaving a thousand

-miles clear of contact on all sides of that tremendous gulf.” For such

-an amount of disturbance on the sun’s atmosphere, what reason can be

-assigned?

-

-The Rev. Mr. Dawes has invented a peculiar contrivance, by means of

-which he has been enabled to scrutinise, under high magnifying power,

-minute portions of the solar disc. He places a metallic screen, pierced

-with a very small hole, in the focus of the telescope, where the image

-of the sun is formed. A small portion only of the image is thus allowed

-to pass through, so that it may be examined by the eye-piece without

-inconveniencing the observer by heat or glare. By this arrangement,

-Mr. Dawes has observed peculiarities in the constitution of the sun’s

-surface which are discernible in no other way.

-

-Before these observations, the dark spots seen on the sun’s surface

-were supposed to be portions of the solid body of the sun, laid bare to

-our view by those immense fluctuations in the luminous regions of its

-atmosphere to which it appears to be subject. It now appears that these

-dark portions are only an additional and inferior stratum of a very

-feebly luminous or illuminated portion of the sun’s atmosphere. This

-again in its turn Mr. Dawes has frequently seen pierced with a smaller

-and usually much more rounded aperture, which would seem at last to

-afford a view of the real solar surface of most intense blackness.

-

-M. Schwabe, of Dessau, has discovered that the abundance or paucity

-of spots displayed by the sun’s surface is subject to a law of

-periodicity. This has been confirmed by M. Wolf, of Berne, who shows

-that the period of these changes, from minimum to minimum, is 11 years

-and 11-hundredths of a year, being exactly at the rate of nine periods

-per century, the last year of each century being a year of minimum. It

-is strongly corroborative of the correctness both of M. Wolf’s period

-and also of the periodicity itself, that of all the instances of the

-appearance of spots on the sun recorded in history, even before the

-invention of the telescope, or of remarkable deficiencies in the sun’s

-light, of which there are great numbers, only two are found to deviate

-as much as two years from M. Wolf’s epochs. Sir William Herschel

-observed that the presence or absence of spots had an influence on the

-temperature of the seasons; his observations have been fully confirmed

-by M. Wolf. And, from an examination of the chronicles of Zurich from

-A.D. 1000 to A.D. 1800, he has come to the conclusion “that years rich

-in solar spots are in general drier and more fruitful than those of an

-opposite character; while the latter are wetter and more stormy than

-the former.”

-

-The most extraordinary fact, however, in connection with the spots on

-the sun’s surface, is the singular coincidence of their periods with

-those great disturbances in the magnetic system of the earth to which

-the epithet of “magnetic storms” has been affixed.

-

-  These disturbances, during which the magnetic needle is greatly

-  and universally agitated (not in a particular limited locality,

-  but at one and the same instant of time over whole continents, or

-  even over the whole earth), are found, so far as observation has

-  hitherto extended, to maintain a parallel, both in respect of their

-  frequency of occurrence and intensity in successive years, with the

-  abundance and magnitude of the spots in the same years, too close

-  to be regarded as fortuitous. The coincidence of the epochs of

-  maxima and minima in the two series of phenomena amounts, indeed,

-  to identity; a fact evidently of most important significance, but

-  which neither astronomical nor magnetic science is yet sufficiently

-  advanced to interpret.--_Herschel’s Outlines._

-

-The signification and connection of the above varying phenomena

-(Humboldt maintains) can never be manifested in their entire importance

-until an uninterrupted series of representations of the sun’s spots

-can be obtained by the aid of mechanical clock-work and photographic

-apparatus, as the result of prolonged observations during the many

-months of serene weather enjoyed in a tropical climate.

-

-  M. Schwabe has thus distinguished himself as an indefatigable

-  observer of the sun’s spots, for his researches received the Royal

-  Astronomical Society’s Medal in 1857. “For thirty years,” said

-  the President at the presentation, “never has the sun exhibited

-  his disc above the horizon of Dessau without being confronted

-  by Schwabe’s imperturbable telescope; and that appears to have

-  happened on an average about 300 days a-year. So, supposing that

-  he had observed but once a-day, he has made 9000 observations,

-  in the course of which he discovered about 4700 groups. This is,

-  I believe, an instance of devoted persistence unsurpassed in

-  the annals of astronomy. The energy of one man has revealed a

-  phenomenon that had eluded the suspicion of astronomers for 200

-  years.”

-

-

-HAS THE MOON AN ATMOSPHERE?

-

-The Moon possesses neither Sea nor Atmosphere of appreciable

-extent. Still, as a negative, in such case, is relative only to

-the capabilities of the instruments employed, the search for the

-indications of a lunar atmosphere has been renewed with fresh

-augmentation of telescopic power. Of such indications, the most

-delicate, perhaps, are those afforded by the occultation of a planet

-by the moon. The occultation of Jupiter, which took place on January

-2, 1857, was observed with this reference, and is said to have

-exhibited no _hesitation_, or change of form or brightness, such as

-would be produced by the refraction or absorption of an atmosphere. As

-respects the sea, if water existed on the moon’s surface, the sun’s

-light reflected from it should be completely polarised at a certain

-elongation of the moon from the sun; and no traces of such light have

-been observed.

-

-MM. Baer and Maedler conclude that the moon is not entirely without

-an atmosphere, but, owing to the smallness of her mass, she is

-incapacitated from holding an extensive covering of gas; and they add,

-“it is possible that this weak envelope may sometimes, through local

-causes, in some measure dim or condense itself.” But if any atmosphere

-exists on our satellite, it must be, as Laplace says, more attenuated

-than what is termed a vacuum in an air-pump.

-

-Mr. Hopkins thinks that if there be any lunar atmosphere, it must

-be very rare in comparison with the terrestrial atmosphere, and

-inappreciable to the kind of observation by which it has been tested;

-yet the absence of any refraction of the light of the stars during

-occultation is a very refined test. Mr. Nasmyth observes that “the

-sudden disappearance of the stars behind the moon, without any change

-or diminution of her brilliancy, is one of the most beautiful phenomena

-that can be witnessed.”

-

-Sir John Herschel observes: The fact of the moon turning always the

-same face towards the earth is, in all probability, the result of an

-elongation of its figure in the direction of a line joining the centres

-of both the bodies, acting conjointly with a non-coincidence of its

-centre of gravity with its centre of symmetry.

-

-If to this we add the supposition that the substance of the moon is

-not homogeneous, and that some considerable preponderance of weight

-is placed excentrically in it, it will be easily apprehended that the

-portion of its surface nearer to that heavier portion of its solid

-content, under all the circumstances of the moon’s rotation, will

-permanently occupy the situation most remote from the earth.

-

-  In what regards its assumption of a definite level, air obeys

-  precisely the same hydrostatical laws as water. The lunar

-  atmosphere would rest upon the lunar ocean, and form in its basin a

-  lake of air, whose upper portions at an altitude such as we are now

-  contemplating would be of excessive tenuity, especially should the

-  provision of air be less abundant in proportion than our own. It by

-  no means follows, then, from the absence of visible indications of

-  water or air on this side of the moon, that the other is equally

-  destitute of them, and equally unfitted for maintaining animal or

-  vegetable life. Some slight approach to such a state of things

-  actually obtains on the earth itself. Nearly all the land is

-  collected in one of its hemispheres, and much the larger portion

-  of the sea in the opposite. There is evidently an excess of heavy

-  material vertically beneath the middle of the Pacific; while not

-  very remote from the point of the globe diametrically opposite

-  rises the great table-land of India and the Himalaya chain, on the

-  summits of which the air has not more than a third of the density

-  it has on the sea-level, and from which animated existence is for

-  ever excluded.--_Herschel’s Outlines_, 5th edit.

-

-

-LIGHT OF THE MOON.

-

-The actual illumination of the lunar surface is not much superior to

-that of weathered sandstone-rock in full sunshine. Sir John Herschel

-has frequently compared the moon setting behind the gray perpendicular

-façade of the Table Mountain at the Cape of Good Hope, illuminated

-by the sun just risen from the opposite quarter of the horizon, when

-it has been scarcely distinguishable in brightness from the rock in

-contact with it. The sun and moon being nearly at equal altitudes, and

-the atmosphere perfectly free from cloud or vapour, its effect is alike

-on both luminaries.

-

-

-HEAT OF MOONLIGHT.

-

-M. Zantedeschi has proved, by a long series of experiments in the

-Botanic Gardens at Venice, Florence, and Padua, that, contrary to the

-general opinion, the diffused rays of moonlight have an influence

-upon the organs of plants, as the Sensitive Plant and the _Desmodium

-gyrans_. The influence was feeble compared with that of the sun; but

-the action is left beyond further question.

-

-Melloni has proved that the rays of the Moon give out a slight degree

-of Heat (see _Things not generally Known_, p. 7); and Professor Piazzi

-Smyth, from a point of the Peak of Teneriffe 8840 feet above the

-sea-level, has found distinctly perceptible the heat radiated from the

-moon, which has been so often sought for in vain in a lower region.

-

-

-SCENERY OF THE MOON.

-

-By means of the telescope, mountain-peaks are distinguished in the

-ash-gray light of the larger spots and isolated brightly-shining points

-of the moon, even when the disc is already more than half illuminated.

-Lambert and Schroter have shown that the extremely variable intensity

-of the ash-gray light of the moon depends upon the greater or less

-degree of reflection of the sunlight which falls upon the earth,

-according as it is reflected from continuous continental masses, full

-of sandy deserts, grassy steppes, tropical forests, and barren rocky

-ground, or from large ocean surfaces. Lambert made the remarkable

-observation (14th of February 1774) of a change of the ash-coloured

-moonlight into an olive-green colour bordering upon yellow. “The moon,

-which then stood vertically over the Atlantic Ocean, received upon its

-right side the green terrestrial light which is reflected towards her

-when the sky is clear by the forest districts of South America.”

-

-Plutarch says distinctly, in his remarkable work _On the Face in the

-Moon_, that we may suppose the _spots_ to be partly deep chasms and

-valleys, partly mountain-peaks, which cast long shadows, like Mount

-Athos, whose shadow reaches Lemnos. The spots cover about two-fifths

-of the whole disc. In a clear atmosphere, and under favourable

-circumstances in the position of the moon, some of the spots are

-visible to the naked eye; as the edge of the Apennines, the dark

-elevated plain Grimaldus, the enclosed _Mare Crisium_, and Tycho,

-crowded round with numerous mountain ridges and craters.

-

-Professor Alexander remarks, that a map of the eastern hemisphere,

-taken with the Bay of Bengal in the centre, would bear a striking

-resemblance to the face of the moon presented to us. The dark portions

-of the moon he considers to be continental elevations, as shown by

-measuring the average height of mountains above the dark and the light

-portions of the moon.

-

-The surface of the moon can be as distinctly seen by a good telescope

-magnifying 1000 times, as it would be if not more than 250 miles

-distant.

-

-

-LIFE IN THE MOON.

-

-A circle of one second in diameter, as seen from the earth, on the

-surface of the moon contains about a square mile. Telescopes,

-therefore, must be greatly improved before we could expect to see signs

-of inhabitants, as manifested by edifices or changes on the surface

-of the soil. It should, however, be observed, that owing to the small

-density of the materials of the moon, and the comparatively feeble

-gravitation of bodies on her surface, muscular force would there go six

-times as far in overcoming the weight of materials as on the earth.

-Owing to the want of air, however, it seems impossible that any form

-of life analogous to those on earth can subsist there. No appearance

-indicating vegetation, or the slightest variation of surface which can

-in our opinion fairly be ascribed to change of season, can any where be

-discerned.--_Sir John Herschel’s Outlines._

-

-

-THE MOON SEEN THROUGH LORD ROSSE’S TELESCOPE.

-

-In 1846, the Rev. Dr. Scoresby had the gratification of observing

-the Moon through the stupendous telescope constructed by Lord Rosse

-at Parsonstown. It appeared like a globe of molten silver, and every

-object to the extent of 100 yards was quite visible. Edifices,

-therefore, of the size of York Minster, or even of the ruins of Whitby

-Abbey, might be easily perceived, if they had existed. But there was

-no appearance of any thing of that nature; neither was there any

-indication of the existence of water, or of an atmosphere. There

-were a great number of extinct volcanoes, several miles in breadth;

-through one of them there was a line of continuance about 150 miles in

-length, which ran in a straight direction, like a railway. The general

-appearance, however, was like one vast ruin of nature; and many of the

-pieces of rock driven out of the volcanoes appeared to lie at various

-distances.

-

-

-MOUNTAINS IN THE MOON.

-

-By the aid of telescopes, we discern irregularities in the surface of

-the moon which can be no other than mountains and valleys,--for this

-plain reason, that we see the shadows cast by the former in the exact

-proportion as to length which they ought to have when we take into

-account the inclinations of the sun’s rays to that part of the moon’s

-surface on which they stand. From micrometrical measurements of the

-lengths of the shadows of the more conspicuous mountains, Messrs. Baer

-and Maedler have given a list of heights for no less than 1095 lunar

-mountains, among which occur all degrees of elevation up to 22,823

-British feet, or about 1400 feet higher than Chimborazo in the Andes.

-

-If Chimborazo were as high in proportion to the earth’s diameter as

-a mountain in the moon known by the name of Newton is to the moon’s

-diameter, its peak would be more than sixteen miles high.

-

-Arago calls to mind, that with a 6000-fold magnifying power, which

-nevertheless could not be applied to the moon with proportionate

-results, the mountains upon the moon would appear to us just as Mont

-Blanc does to the naked eye when seen from the Lake of Geneva.

-

-We sometimes observe more than half the surface of the moon, the

-eastern and northern edges being more visible at one time, and the

-western or southern at another. By means of this libration we are

-enabled to see the annular mountain Malapert (which occasionally

-conceals the moon’s south pole), the arctic landscape round the crater

-of Gioja, and the large gray plane near Endymion, which conceals in

-superficial extent the _mare vaporum_.

-

-Three-sevenths of the moon are entirely concealed from our observation;

-and must always remain so, unless some new and unexpected disturbing

-causes come into play.--_Humboldt._

-

-  The first object to which Galileo directed his telescope was the

-  mountainous parts of the moon, when he showed how their summits

-  might be measured: he found in the moon some circular districts

-  surrounded on all sides by mountains similar to the form of

-  Bohemia. The measurements of the mountains were made by the method

-  of the tangents of the solar ray. Galileo, as Helvetius did still

-  later, measured the distance of the summit of the mountains from

-  the boundary of the illuminated portion at the moment when the

-  mountain summit was first struck by the solar ray. Humboldt found

-  no observations of the lengths of the shadows of the mountains:

-  the summits were “much higher than the mountains on our earth.”

-  The comparison is remarkable, since, according to Riccioli,

-  very exaggerated ideas of the height of our mountains were then

-  entertained. Galileo like all other observers up to the close of

-  the eighteenth century, believed in the existence of many seas and

-  of a lunar atmosphere.

-

-

-THE MOON AND THE WEATHER.

-

-The only influence of the Moon on the Weather of which we have any

-decisive evidence is the tendency to disappearance of clouds under the

-full moon, which Sir John Herschel refers to its heat being much more

-readily absorbed in traversing transparent media than direct solar

-heat, and being extinguished in the upper regions of our atmosphere,

-never reaches the surface of the atmosphere at all.

-

-

-THE MOON’S ATTRACTION.

-

-Mr. G. P. Bond of Cambridge, by some investigations to ascertain

-whether the Attraction of the Moon has any effect upon the motion of

-a pendulum, and consequently upon the rate of a clock, has found the

-last to be changed to the amount of 9/1000 of a second daily. At

-the equator the moon’s attraction changes the weight of a body only

-1/7000000 of the whole; yet this force is sufficient to produce the

-vast phenomena of the tides!

-

-It is no slight evidence of the importance of analysis, that Laplace’s

-perfect theory of tides has enabled us in our astronomical ephemerides

-to predict the height of spring-tides at the periods of new and full

-moon, and thus put the inhabitants of the sea on their guard against

-the increased danger attending the lunar revolutions.

-

-

-MEASURING THE EARTH BY THE MOON.

-

-As the form of the Earth exerts a powerful influence on the motion

-of other cosmical bodies, and especially on that of its neighbouring

-satellite, a more perfect knowledge of the motion of the latter will

-enable us reciprocally to draw an inference regarding the figure of

-the earth. Thus, as Laplace ably remarks: “an astronomer, without

-leaving his observatory, may, by a comparison of lunar theory with true

-observations, not only be enabled to determine the form and size of

-the earth, but also its distance from the sun and moon; results that

-otherwise could only be arrived at by long and arduous expeditions

-to the most remote parts of both hemispheres.” The compression which

-may be inferred from lunar inequalities affords an advantage not

-yielded by individual measurements of degrees or experiments with the

-pendulum, since it gives a mean amount which is referable to the whole

-planet.--_Humboldt’s Cosmos_, vol. i.

-

-The distance of the moon from the earth is about 240,000 miles; and

-if a railway-carriage were to travel at the rate of 1000 miles a-day,

-it would be eight months in reaching the moon. But that is nothing

-compared with the length of time it would occupy a locomotive to reach

-the sun from the earth: if travelling at the rate of 1000 miles a-day,

-it would require 260 years to reach it.

-

-

-CAUSE OF ECLIPSES.

-

-As the Moon is at a very moderate distance from us (astronomically

-speaking), and is in fact our nearest neighbour, while the sun and

-stars are in comparison immensely beyond it, it must of necessity

-happen that at one time or other it must _pass over_, and _occult_ or

-_eclipse_, every star or planet within its zone, and, as seen from

-the _surface_ of the earth, even somewhat beyond it. Nor is the sun

-itself exempt from being thus hidden whenever any part of the moon’s

-disc, in this her tortuous course, comes to _overlap_ any part of the

-space occupied in the heavens by that luminary. On these occasions

-is exhibited the most striking and impressive of all the occasional

-phenomena of astronomy, an _Eclipse of the Sun_, in which a greater or

-less portion, or even in some conjunctures the whole of its disc, is

-obscured, and, as it were, obliterated, by the superposition of that

-of the moon, which appears upon it as a circularly-terminated black

-spot, producing a temporary diminution of daylight, or even nocturnal

-darkness, so that the stars appear as if at midnight.--_Sir John

-Herschel’s Outlines._

-

-

-VAST NUMBERS IN THE UNIVERSE.

-

-The number of telescopic stars in the Milky Way uninterrupted by

-any nebulæ is estimated at 18,000,000. To compare this number with

-something analogous, Humboldt calls attention to the fact, that there

-are not in the whole heavens more than about 8000 stars, between

-the first and the sixth magnitudes, visible to the naked eye. The

-barren astonishment excited by numbers and dimensions in space when

-not considered with reference to applications engaging the mental

-and perceptive powers of man, is awakened in both extremes of the

-universe--in the celestial bodies as in the minutest animalcules. A

-cubic inch of the polishing slate of Bilin contains, according to

-Ehrenberg, 40,000 millions of the siliceous shells of Galionellæ.

-

-

-FOR WHAT PURPOSE WERE THE STARS CREATED?

-

-Surely not (says Sir John Herschel) to illuminate _our_ nights, which

-an additional moon of the thousandth part of the size of our own

-would do much better; nor to sparkle as a pageant void of meaning and

-reality, and bewilder us among vain conjectures. Useful, it is true,

-they are to man as points of exact and permanent reference; but he must

-have studied astronomy to little purpose, who can suppose man to be the

-only object of his Creator’s care, or who does not see in the vast and

-wonderful apparatus around us provision for other races of animated

-beings. The planets derive their light from the sun; but that cannot be

-the case with the stars. These doubtless, then, are themselves suns;

-and may perhaps, each in its sphere, be the presiding centre round

-which other planets, or bodies of which we can form no conception from

-any analogy offered by our own system, are circulating.[19]

-

-

-NUMBER OF STARS.

-

-Various estimates have been hazarded on the Number of Stars throughout

-the whole heavens visible to us by the aid of our colossal telescopes.

-Struve assumes for Herschel’s 20-feet reflector, that a magnifying

-power of 180 would give 5,800,000 for the number of stars lying within

-the zones extending 30° on either side of the equator, and 20,374,000

-for the whole heavens. Sir William Herschel conjectured that 18,000,000

-of stars in the Milky Way might be seen by his still more powerful

-40-feet reflecting telescope.--_Humboldt’s Cosmos_, vol. iii.

-

-The assumption that the extent of the starry firmament is literally

-infinite has been made by Dr. Olbers the basis of a conclusion that the

-celestial spaces are in some slight degree deficient in _transparency_;

-so that all beyond a certain distance is and must remain for ever

-unseen, the geometrical progression of the extinction of light far

-outrunning the effect of any conceivable increase in the power of

-our telescopes. Were it not so, it is argued that every part of the

-celestial concave ought to shine with the brightness of the solar disc,

-since no visual ray could be so directed as not, in some point or other

-of its infinite length, to encounter such a disc.--_Edinburgh Review_,

-Jan. 1848.

-

-

-STARS THAT HAVE DISAPPEARED.

-

-Notwithstanding the great accuracy of the catalogued positions of

-telescopic fixed stars and of modern star-maps, the certainty of

-conviction that a star in the heavens has actually disappeared since

-a certain epoch can only be arrived at with great caution. Errors of

-actual observation, of reduction, and of the press, often disfigure the

-very best catalogues. The disappearance of a heavenly body from the

-place in which it had been before distinctly seen, may be the result

-of its own motion as much as of any such diminution of its photometric

-process as would render the waves of light too weak to excite our

-organs of sight. What we no longer see, is not necessarily annihilated.

-The idea of destruction or combustion, as applied to disappearing

-stars, belongs to the age of Tycho Brahe. Even Pliny makes it a

-question. The apparent eternal cosmical alternation of existence and

-destruction is not annihilation; it is merely the transition of matter

-into new forms, into combinations which are subject to new processes.

-Dark cosmical bodies may by a renewed process of light again become

-luminous.--_Humboldt’s Cosmos_, vol. iii.

-

-

-THE POLE-STAR FOUR THOUSAND YEARS AGO.

-

-Sir John Herschel, in his _Outlines of Astronomy_, thus shows the

-changes in the celestial pole in 4000 years:

-

-  At the date of the erection of the Pyramid of Gizeh, which precedes

-  the present epoch by nearly 4000 years, the longitudes of all the

-  stars were less by 55° 45′ than at present. Calculating from

-  this datum the place of the pole of the heavens among the stars,

-  it will be found to fall near α Draconis; its distance from that

-  star being 3° 44′ 25″. This being the most conspicuous star in

-  the immediate neighbourhood, was therefore the Pole Star of that

-  epoch. The latitude of Gizeh being just 30° north, and consequently

-  the altitude of the North Pole there also 30°, it follows that

-  the star in question must have had at its lowest culmination at

-  Gizeh an altitude of 25° 15′ 35″. Now it is a remarkable fact,

-  that of the nine pyramids still existing at Gizeh, six (including

-  all the largest) have the narrow passages by which alone they can

-  be entered (all which open out on the northern faces of their

-  respective pyramids) inclined to the horizon downwards at angles

-  the mean of which is 26° 47′. At the bottom of every one of these

-  passages, therefore, the Pole Star must have been visible at its

-  lower culmination; a circumstance which can hardly be supposed

-  to have been unintentional, and was doubtless connected (perhaps

-  superstitiously) with the astronomical observations of that star,

-  of whose proximity to the pole at the epoch of the erection of

-  these wonderful structures we are thus furnished with a monumental

-  record of the most imperishable nature.

-

-

-THE PLEIADES.

-

-The Pleiades prove that, several thousand years ago even as now,

-stars of the seventh magnitude were invisible to the naked eye of

-average visual power. The group consists of seven stars, of which six

-only, of the third, fourth, and fifth magnitudes, could be readily

-distinguished. Of these Ovid says (_Fast._ iv. 170):

-

-    “Quæ septem dici, sex tamen esse solent.”

-

-Aratus states there were only six stars visible in the Pleiades.

-

-One of the daughters of Atlas, Merope, the only one who was wedded to

-a mortal, was said to have veiled herself for very shame and to have

-disappeared. This is probably the star of the seventh magnitude, which

-we call Celæne; for Hipparchus, in his commentary on Aratus, observes

-that on clear moonless nights _seven stars_ may actually be seen.

-

-The Pleiades were doubtless known to the rudest nations from the

-earliest times; they are also called the _mariner’s stars_. The name is

-from πλεῖν (_plein_), ‘to sail.’ The navigation of the Mediterranean

-lasted from May to the beginning of November, from the early rising

-to the early setting of the Pleiades. In how many beautiful effusions

-of poetry and sentiment has “the Lost Pleiad” been deplored!--and, to

-descend to more familiar illustration of this group, the “Seven Stars,”

-the sailors’ favourites, and a frequent river-side public-house sign,

-may be traced to the Pleiades.

-

-

-CHANGE OF COLOUR IN THE STARS.

-

-The scintillation or twinkling of the stars is accompanied by

-variations of colour, which have been remarked from a very early age.

-M. Arago states, upon the authority of M. Babinet, that the name of

-Barakesch, given by the Arabians to Sirius, signifies _the star of

-a thousand colours_; and Tycho Brahe, Kepler, and others, attest to

-similar change of colour in twinkling. Even soon after the invention

-of the telescope, Simon Marius remarked that by removing the eye-piece

-of the telescope the images of the stars exhibited rapid fluctuations

-of brightness and colour. In 1814 Nicholson applied to the telescope a

-smart vibration, which caused the image of the star to be transformed

-into a curved line of light returning into itself, and diversified by

-several colours; each colour occupied about a third of the whole length

-of the curve, and by applying ten vibrations in a second, the light of

-Sirius in that time passed through thirty changes of colour. Hence the

-stars in general shine only by a portion of their light, the effect of

-twinkling being to diminish their brightness. This phenomenon M. Arago

-explains by the principle of the interference of light.

-

-Ptolemy is said to have noted Sirius as a _red_ star, though it is now

-white. Sirius twinkles with red and blue light, and Ptolemy’s eyes,

-like those of several other persons, may have been more sensitive to

-the _red_ than to the _blue_ rays.--_Sir David Brewster’s More Worlds

-than One_, p. 235.

-

-Some of the double stars are of very different and dissimilar colours;

-and to the revolving planetary bodies which apparently circulate around

-them, a day lightened by a red light is succeeded by, not a night, but

-a day equally brilliant, though illuminated only by a green light.

-

-

-DISTANCE OF THE NEAREST FIXED STAR FROM THE EARTH.

-

-Sir John Herschel wrote in 1833: “What is the distance of the nearest

-fixed star? What is the scale on which our visible firmament is

-constructed? And what proportion do its dimensions bear to those of our

-own immediate system? To this, however, astronomy has hitherto proved

-unable to supply an answer. All we know on this subject is negative.”

-To these questions, however, an answer can now be given. Slight

-changes of position of some of the stars, called parallax, have been

-distinctly observed and measured; and among these stars No. 61 Cygni of

-Flamstead’s catalogue has a parallax of 5″, and that of α Centauri has

-a proper motion of 4″ per annum.

-

-The same astronomer states that each second of parallax indicates a

-distance of 20 billions of miles, or 3¼ years’ journey of light. Now

-the light sent to us by the sun, as compared with that sent by Sirius

-and α Centauri, is about 22 thousand millions to 1. “Hence, from the

-parallax assigned above to that star, it is easy to conclude that

-its intrinsic splendour, as compared with that of our sun at equal

-distances, is 2·3247, that of the sun being unity. The light of Sirius

-is four times that of α Centauri, and its parallax only 0·15″. This,

-in effect, ascribes to it an intrinsic splendour equal to 96·63 times

-that of α Centauri, and therefore 224·7 times that of our sun.”

-

-This is justly regarded as one of the most brilliant triumphs of

-astronomical science, for the delicacy of the investigation is

-almost inconceivable; yet the reasoning is as unimpeachable as the

-demonstration of a theorem of Euclid.

-

-

-LIGHT OF A STAR SIXTEENFOLD THAT OF THE SUN.

-

-The bright star in the constellation of the Lyre, termed Vega, is the

-brightest in the northern hemisphere; and the combined researches of

-Struve, father and son, have found that the distance of this star from

-the earth is no less than 130 billions of miles! Light travelling

-at the rate of 192 thousand miles in a second consequently occupies

-twenty-one years in passing from this star to the earth. Now it has

-been found, by comparing the light of Vega with the light of the

-sun, that if the latter were removed to the distance of 130 billions

-of miles, his apparent brightness would not amount to more than the

-sixteenth part of the apparent brightness of Vega. We are therefore

-warranted in concluding that the light of Vega is equal to that of

-sixteen suns.

-

-

-DIVERSITIES OF THE PLANETS.

-

-In illustration of the great diversity of the physical peculiarities

-and probable condition of the planets, Sir John Herschel describes

-the intensity of solar radiation as nearly seven times greater on

-Mercury than on the earth, and on Uranus 330 times less; the proportion

-between the two extremes being that of upwards of 2000 to 1. Let any

-one figure to himself, (adds Sir John,) the condition of our globe

-were the sun to be septupled, to say nothing of the greater ratio; or

-were it diminished to a seventh, or to a 300th of its actual power!

-Again, the intensity of gravity, or its efficacy in counteracting

-muscular power and repressing animal activity, on Jupiter is nearly

-two-and-a-half times that on the earth; on Mars not more than one-half;

-on the moon one-sixth; and on the smaller planets probably not more

-than one-twentieth; giving a scale of which the extremes are in the

-proportion of sixty to one. Lastly, the density of Saturn hardly

-exceeds one-eighth of the mean density of the earth, so that it must

-consist of materials not much heavier than cork.

-

-  Jupiter is eleven times, Saturn ten times, Uranus five times, and

-  Neptune nearly six times, the diameter of our earth.

-

-  These four bodies revolve in space at such distances from the sun,

-  that if it were possible to start thence for each in succession,

-  and to travel at the railway speed of 33 miles per hour, the

-  traveller would reach

-

-    Jupiter in  1712 years

-    Saturn      3113   ”

-    Uranus      6226   ”

-    Neptune     9685   ”

-

-  If, therefore, a person had commenced his journey at the period of

-  the Christian era, he would now have to travel nearly 1300 years

-  before he would arrive at the planet Saturn; more than 4300 years

-  before he would reach Uranus; and no less than 7800 years before he

-  could reach the orbit of Neptune.

-

-  Yet the light which comes to us from these remote confines of the

-  solar system first issued from the sun, and is then reflected

-  from the surface of the planet. When the telescope is turned

-  towards Neptune, the observer’s eye sees the object by means of

-  light that issued from the sun eight hours before, and which

-  since then has passed nearly twice through that vast space which

-  railway speed would require almost a century of centuries to

-  accomplish.--_Bouvier’s Familiar Astronomy._

-

-

-GRAND RESULTS OF THE DISCOVERY OF JUPITER’S SATELLITES.

-

-This discovery, one of the first fruits of the invention of the

-telescope, and of Galileo’s early and happy idea of directing its

-newly-found powers to the examination of the heavens, forms one of

-the most memorable epochs in the history of astronomy. The first

-astronomical solution of the great problem of _the longitude_,

-practically the most important for the interests of mankind which has

-ever been brought under the dominion of strict scientific principles,

-dates immediately from this discovery. The final and conclusive

-establishment of the Copernican system of astronomy may also be

-considered as referable to the discovery and study of this exquisite

-miniature system, in which the laws of the planetary motions, as

-ascertained by Kepler, and specially that which connects their periods

-and distances, were specially traced, and found to be satisfactorily

-maintained. And (as if to accumulate historical interest on this point)

-it is to the observation of the eclipses of Jupiter’s satellites

-that we owe the grand discovery of the aberration of light, and the

-consequent determination of the enormous velocity of that wonderful

-element--192,000 miles per second. Mr. Dawes, in 1849, first noticed

-the existence of round, well-defined, bright spots on the belts of

-Jupiter. They vary in situation and number, as many as ten having been

-seen on one occasion. As the belts of Jupiter have been ascribed to the

-existence of currents analogous to our trade-winds, causing the body of

-Jupiter to be visible through his cloudy atmosphere, Sir John Herschel

-conjectures that those bright spots may possibly be insulated masses

-of clouds of local origin, similar to the cumuli which sometimes cap

-ascending columns of vapour in our atmosphere.

-

-It would require nearly 1300 globes of the size of our earth to make

-one of the bulk of Jupiter. A railway-engine travelling at the rate of

-thirty-three miles an hour would travel round the earth in a month,

-but would require more than eleven months to perform a journey round

-Jupiter.

-

-

-WAS SATURN’S RING KNOWN TO THE ANCIENTS?

-

-In Maurice’s _Indian Antiquities_ is an engraving of Sani, the Saturn

-of the Hindoos, taken from an image in a very ancient pagoda, which

-represents the deity encompassed by a _ring_ formed of two serpents.

-Hence it is inferred that the ancients were acquainted with the

-existence of the ring of Saturn.

-

-Arago mentions the remarkable fact of the ring and fourth satellite of

-Saturn having been seen by Sir W. Herschel with his smaller telescope

-by the naked eye, without any eye-piece.

-

-The first or innermost of Saturn’s satellites is nearer to the central

-body than any other of the secondary planets. Its distance from the

-centre of Saturn is 80,088 miles; from the surface of the planet

-47,480 miles; and from the outmost edge of the ring only 4916 miles.

-The traveller may form to himself an estimate of the smallness of

-this amount by remembering the statement of the well-known navigator,

-Captain Beechey, that he had in three years passed over 72,800 miles.

-

-According to very recent observations, Saturn’s ring is divided into

-_three_ separate rings, which, from the calculations of Mr. Bond, an

-American astronomer, must be fluid. He is of opinion that the number

-of rings is continually changing, and that their maximum number, in

-the normal condition of the mass, does not exceed _twenty_. Mr. Bond

-likewise maintains that the power which sustains the centre of gravity

-of the _ring_ is not in the planet itself, but in its satellites; and

-the satellites, though constantly disturbing the ring, actually sustain

-it in the very act of perturbation. M. Otto Struve and Mr. Bond have

-lately studied with the great Munich telescope, at the observatory of

-Pulkowa, the _third_ ring of Saturn, which Mr. Lassell and Mr. Bond

-discovered to be _fluid_. They saw distinctly the dark interval between

-this fluid ring and the two old ones, and even measured its dimensions;

-and they perceived at its inner margin an edge feebly illuminated,

-which they thought might be the commencement of a fourth ring. These

-astronomers are of opinion, that the fluid ring is not of very recent

-formation, and that it is not subject to rapid change; and they have

-come to the extraordinary conclusion, that the inner border of the ring

-has, since the time of Huygens, been gradually approaching to the body

-of Saturn, and that _we may expect, sooner or later, perhaps in some

-dozen of years, to see the rings united with the body of the planet_.

-But this theory is by other observers pronounced untenable.

-

-

-TEMPERATURE OF THE PLANET MERCURY.

-

-Mercury being so much nearer to the Sun than the Earth, he receives,

-it is supposed, seven times more heat than the earth. Mrs. Somerville

-says: “On Mercury, the mean heat arising from the intensity of the

-sun’s rays must be above that of boiling quicksilver, and water would

-boil even at the poles.” But he may be provided with an atmosphere

-so constituted as to absorb or reflect a great portion of the

-superabundant heat; so that his inhabitants (if he have any) may enjoy

-a climate as temperate as any on our globe.

-

-

-SPECULATIONS ON VESTA AND PALLAS.

-

-The most remarkable peculiarities of these ultra-zodiacal planets,

-according to Sir John Herschel, must lie in this condition of their

-state: a man placed on one of them would spring with ease sixty feet

-high, and sustain no greater shock in his descent than he does on the

-earth from leaping a yard. On such planets, giants might exist; and

-those enormous animals which on the earth require the buoyant power of

-water to counteract their weight, might there be denizens of the land.

-But of such speculations there is no end.

-

-

-IS THE PLANET MARS INHABITED?

-

-The opponents of the doctrine of the Plurality of Worlds allow that a

-greater probability exists of Mars being inhabited than in the case of

-any other planet. His diameter is 4100 miles; and his surface exhibits

-spots of different hues,--the _seas_, according to Sir John Herschel,

-being _green_, and the land _red_. “The variety in the spots,” says

-this astronomer, “may arise from the planet not being destitute of

-atmosphere and cloud; and what adds greatly to the probability of this,

-is the appearance of brilliant white spots at its poles, which have

-been conjectured, with some probability, to be snow, as they disappear

-when they have been long exposed to the sun, and are greatest when

-emerging from the long night of their polar winter, the snow-line then

-extending to about six degrees from the pole.” “The length of the day,”

-says Sir David Brewster, “is almost exactly twenty-four hours,--the

-same as that of the earth. Continents and oceans and green savannahs

-have been observed upon Mars, and the snow of his polar regions has

-been seen to disappear with the heat of summer.” We actually see the

-clouds floating in the atmosphere of Mars, and there is the appearance

-of land and water on his disc. In a sketch of this planet, as seen in

-the pure atmosphere of Calcutta by Mr. Grant, it appears, to use his

-words, “actually as a little world,” and as the earth would appear at

-a distance, with its seas and continents of different shades. As the

-diameter of Mars is only about one half that of our earth, the weight

-of bodies will be about one half what it would be if they were placed

-upon our globe.

-

-

-DISCOVERY OF THE PLANET NEPTUNE.

-

-This noble discovery marked in a signal manner the maturity of

-astronomical science. The proof, or at least the urgent presumption,

-of the existence of such a planet, as a means of accounting (by its

-attraction) for certain small irregularities observed in the motions

-of Uranus, was afforded almost simultaneously by the independent

-researches of two geometers, Mr. Adams of Cambridge, and M. Leverrier

-of Paris, who were enabled _from theory alone_ to calculate whereabouts

-it ought to appear in the heavens, _if visible_, the places thus

-independently calculated agreeing surprisingly. _Within a single

-degree_ of the place assigned by M. Leverrier’s calculations, and by

-him communicated to Dr. Galle of the Royal Observatory at Berlin, it

-was actually found by that astronomer on the very first night after

-the receipt of that communication, on turning a telescope on the spot,

-and comparing the stars in its immediate neighbourhood with those

-previously laid down in one of the zodiacal charts. This remarkable

-verification of an indication so extraordinary took place on the 23d of

-September 1846.[20]--_Sir John Herschel’s Outlines._

-

-Neptune revolves round the sun in about 172 years, at a mean distance

-of thirty,--that of Uranus being nineteen, and that of the earth one:

-and by its discovery the solar system has been extended _one thousand

-millions of miles_ beyond its former limit.

-

-Neptune is suspected to have a ring, but the suspicion has not been

-confirmed. It has been demonstrated by the observations of Mr. Lassell,

-M. Otto Struve, and Mr. Bond, to be attended by at least one satellite.

-

-One of the most curious facts brought to light by the discovery of

-Neptune, is the failure of Bode’s law to give an approximation to its

-distance from the sun; a striking exemplification of the danger of

-trusting to the universal applicability of an empirical law. After

-standing the severe test which led to the discovery of the asteroids,

-it seemed almost contrary to the laws of probability that the discovery

-of another member of the planetary system should prove its failure as

-an universal rule.

-

-

-MAGNITUDE OF COMETS.

-

-Although Comets have a smaller mass than any other cosmical

-bodies--being, according to our present knowledge, probably not equal

-to 1/5000th part of the earth’s mass--yet they occupy the largest

-space, as their tails in several instances extend over many millions of

-miles. The cone of luminous vapour which radiates from them has been

-found in some cases (as in 1680 and 1811) equal to the length of the

-earth’s distance from the sun, forming a line that intersects both the

-orbits of Venus and Mercury. It is even probable that the vapour of

-the tails of comets mingled with our atmosphere in the years 1819 and

-1823.--_Humboldt’s Cosmos_, vol. i.

-

-

-COMETS VISIBLE IN SUNSHINE--THE GREAT COMET OF 1843.

-

-The phenomenon of the tail of a Comet being visible in bright Sunshine,

-which is recorded of the comet of 1402, occurred again in the case of

-the large comet of 1843, whose nucleus and tail were seen in North

-America on February 28th (according to the testimony of J. G. Clarke,

-of Portland, State of Maine), between one and three o’clock in the

-afternoon. The distance of the very dense nucleus from the sun’s

-light admitted of being measured with much exactness. The nucleus and

-tail (a darker space intervening) appeared like a very pure white

-cloud.--_American Journal of Science_, vol. xiv.

-

-E. C. Otté, the translator of Bohn’s edition of Humboldt’s _Cosmos_,

-at New Bedford, Massachusetts, U.S., Feb. 28th, 1843, distinctly saw

-the above comet between one and two in the afternoon. The sky at the

-time was intensely blue, and the sun shining with a dazzling brightness

-unknown in European climates.

-

-This very remarkable Comet, seen in England on the 17th of March

-1843, had a nucleus with the appearance of a planetary disc, and the

-brightness of a star of the first or second magnitude. It had a double

-tail divided by a dark line. At the Cape of Good Hope it was seen in

-full daylight, and in the immediate vicinity of the sea; but the most

-remarkable fact in its history was its near approach to the sun, its

-distance from his surface being only _one-fourteenth_ of his diameter.

-The heat to which it was exposed, therefore, was much greater than that

-which Sir Isaac Newton ascribed to the comet of 1680, namely 200 times

-that of red-hot iron. Sir John Herschel has computed that it must have

-been 24 times greater than that which was produced in the focus of

-Parker’s burning lens, 32 inches in diameter, which melts crystals of

-quartz and agate.[21]

-

-

-THE MILKY WAY UNFATHOMABLE.

-

-M. Struve of Pulkowa has compared Sir William Herschel’s opinion

-on this subject, as maintained in 1785, with that to which he was

-subsequently led; and arrives at the conclusion that, according to Sir

-W. Herschel himself, the visible extent of the Milky Way increases with

-the penetrating power of the telescopes employed; that it is impossible

-to discover by his instruments the termination of the Milky Way (as an

-independent cluster of stars); and that even his gigantic telescope of

-forty feet focal length does not enable him to extend our knowledge

-of the Milky Way, which is incapable of being sounded. Sir William

-Herschel’s _Theory of the Milky Way_ was as follows: He considered

-our solar system, and all the stars which we can see with the eye, as

-placed within, and constituting a part of, the nebula of the Milky Way,

-a congeries of many millions of stars, so that the projection of these

-stars must form a luminous track on the concavity of the sky; and by

-estimating or counting the number of stars in different directions, he

-was able to form a rude judgment of the probable form of the nebula,

-and of the probable position of the solar system within it.

-

-This remarkable belt has maintained from the earliest ages the same

-relative situation among the stars; and, when examined through powerful

-telescopes, is found (wonderful to relate!) _to consist entirely of

-stars scattered by millions_, like glittering dust, on the black ground

-of the general heavens.

-

-

-DISTANCES OF NEBULÆ.

-

-These are truly astounding. Sir William Herschel estimated the distance

-of the annular nebula between Beta and Gamma Lyræ to be from our system

-950 times that of Sirius; and a globular cluster about 5½° south-east

-of Beta Sir William computed to be one thousand three hundred billions

-of miles from our system. Again, in Scutum Sobieski is one nebula in

-the shape of a horseshoe; but which, when viewed with high magnifying

-power, presents a different appearance. Sir William Herschel estimated

-this nebula to be 900 times farther from us than Sirius. In some parts

-of its vicinity he observed 588 stars in his telescope at one time;

-and he counted 258,000 in a space 10° long and 2½° wide. There is a

-globular cluster between the mouths of Pegasus and Equuleus, which

-Sir William Herschel estimated to be 243 times farther from us than

-Sirius. Caroline Herschel discovered in the right foot of Andromeda

-a nebula of enormous dimensions, placed at an inconceivable distance

-from us: it consists probably of myriads of solar systems, which, taken

-together, are but a point in the universe. The nebula about 10° west of

-the principal star in Triangulum is supposed by Sir William Herschel

-to be 344 times the distance of Sirius from the earth, which would be

-the immense sum of nearly seventeen thousand billions of miles from our

-planet.

-

-

-INFINITE SPACE.

-

-After the straining mind has exhausted all its resources in attempting

-to fathom the distance of the smallest telescopic star, or the faintest

-nebula, it has reached only the visible confines of the sidereal

-creation. The universe of stars is but an atom in the universe of

-space; above it, and beneath it, and around it, there is still infinity.

-

-

-ORIGIN OF OUR PLANETARY SYSTEM. THE NEBULAR HYPOTHESIS.[22]

-

-The commencement of our Planetary System, including the sun, must,

-according to Kant and Laplace, be regarded as an immense nebulous mass

-filling the portion of space which is now occupied by our system far

-beyond the limits of Neptune, our most distant planet. Even now we

-perhaps see similar masses in the distant regions of the firmament, as

-patches of nebulæ, and nebulous stars; within our system also, comets,

-the zodiacal light, the corona of the sun during a total eclipse,

-exhibit resemblances of a nebulous substance, which is so thin that the

-light of the stars passes through it unenfeebled and unrefracted. If we

-calculate the density of the mass of our planetary system, according

-to the above assumption, for the time when it was a nebulous sphere

-which reached to the path of the outmost planet, we should find that

-it would require several cubic miles of such matter to weigh a single

-grain.--_Professor Helmholtz._

-

-A quarter of a century ago, Sir John Herschel expressed his opinion

-that those nebulæ which were not resolved into individual stars by the

-highest powers then used, might be hereafter completely resolved by a

-further increase of optical power:

-

-  In fact, this probability has almost been converted into a

-  certainty by the magnificent reflecting telescope constructed by

-  Lord Rosse, of 6 feet in aperture, which has resolved, or rendered

-  resolvable, multitudes of nebulæ which had resisted all inferior

-  powers. The sublimity of the spectacle afforded by that instrument

-  of some of the larger globular and other clusters is declared by

-  all who have witnessed it to be such as no words can express.[23]

-

-  Although, therefore, nebulæ do exist, which even in this powerful

-  telescope appear as nebulæ, without any sign of resolution, it may

-  very reasonably be doubted whether there be really any essential

-  physical distinction between nebulæ and clusters of stars, at least

-  in the nature of the matter of which they consist; and whether the

-  distinction between such nebulæ as are easily resolved, barely

-  resolvable with excellent telescopes, and altogether irresolvable

-  with the best, be any thing else than one of degree, arising merely

-  from the excessive minuteness and multitude of the stars of which

-  the latter, as compared with the former, consist.--_Outlines of

-  Astronomy_, 5th edit. 1858.

-

-It should be added, that Sir John Herschel considers the “nebular

-hypothesis” and the above theory of sidereal aggregation to stand quite

-independent of each other.

-

-

-ORIGIN OF HEAT IN OUR SYSTEM.

-

-Professor Helmholtz, assuming that at the commencement the density of

-the nebulous matter was a vanishing quantity, as compared with the

-present density of the sun and planets, calculates how much work has

-been performed by the condensation; how much of this work still exists

-in the form of mechanical force, as attraction of the planets towards

-the sun, and as _vis viva_ of their motion; and finds by this how much

-of the force has been converted into heat.

-

-  The result of this calculation is, that only about the 45th part

-  of the original mechanical force remains as such, and that the

-  remainder, converted into heat, would be sufficient to raise a

-  mass of water equal to the sun and planets taken together, not

-  less than 28,000,000 of degrees of the centigrade scale. For the

-  sake of comparison, Professor Helmholtz mentions that the highest

-  temperature which we can produce by the oxy-hydrogen blowpipe,

-  which is sufficient to vaporise even platina, and which but few

-  bodies can endure, is estimated at about 2000 degrees. Of the

-  action of a temperature of 28,000,000 of such degrees we can form

-  no notion. If the mass of our entire system were of pure coal, by

-  the combustion of the whole of it only the 350th part of the above

-  quantity would be generated.

-

-  The store of force at present possessed by our system is equivalent

-  to immense quantities of heat. If our earth were by a sudden shock

-  brought to rest in her orbit--which is not to be feared in the

-  existing arrangement of our system--by such a shock a quantity of

-  heat would be generated equal to that produced by the combustion of

-  fourteen such earths of solid coal. Making the most unfavourable

-  assumption as to its capacity for heat, that is, placing it equal

-  to that of water, the mass of the earth would thereby be heated

-  11,200°; it would therefore be quite fused, and for the most part

-  reduced to vapour. If, then, the earth, after having been thus

-  brought to rest, should fall into the sun, which of course would be

-  the case, the quantity of heat developed by the shock would be 400

-  times greater.

-

-

-AN ASTRONOMER’S DREAM VERIFIED.

-

-The most fertile region in astronomical discovery during the last

-quarter of a century has been the planetary members of the solar

-system. In 1833, Sir John Herschel enumerated ten planets as visible

-from the earth, either by the unaided eye or by the telescope; the

-number is now increased more than fivefold. With the exception of

-Neptune, the discovery of new planets is confined to the class called

-Asteroids. These all revolve in elliptic orbits between those of

-Jupiter and Mars. Zitius of Wittemberg discovered an empirical law,

-which seemed to govern the distances of the planets from the sun; but

-there was a remarkable interruption in the law, according to which a

-planet ought to have been placed between Mars and Jupiter. Professor

-Bode of Berlin directed the attention of astronomers to the possibility

-of such a planet existing; and in seven years’ observations from the

-commencement of the present century, not one but four planets were

-found, differing widely from one another in the elements of their

-orbits, but agreeing very nearly at their mean distances from the sun

-with that of the supposed planet. This curious coincidence of the mean

-distances of these four asteroids with the planet according to Bode’s

-law, as it is generally called, led to the conjecture that these four

-planets were but fragments of the missing planet, blown to atoms by

-some internal explosion, and that many more fragments might exist, and

-be possibly discovered by diligent search.

-

-Concerning this apparently wild hypothesis, Sir John Herschel offered

-the following remarkable apology: “This may serve as a specimen of the

-dreams in which astronomers, like other speculators, occasionally and

-harmlessly indulge.”

-

-The dream, wild as it appeared, has been realised now. Sir John, in the

-fifth edition of his _Outlines of Astronomy_, published in 1858, tells

-us:

-

-  Whatever may be thought of such a speculation as a physical

-  hypothesis, this conclusion has been verified to a considerable

-  extent as a matter of fact by subsequent discovery, the result

-  of a careful and minute examination and mapping down of the

-  smaller stars in and near the zodiac, undertaken with that express

-  object. Zodiacal charts of this kind, the product of the zeal and

-  industry of many astronomers, have been constructed, in which

-  every star down to the ninth, tenth, or even lower magnitudes, is

-  inserted; and these stars being compared with the actual stars of

-  the heavens, the intrusion of any stranger within their limits

-  cannot fail to be noticed when the comparison is systematically

-  conducted. The discovery of Astræa and Hebe by Professor Hencke,

-  in 1845 and 1847, revived the flagging spirit of inquiry in this

-  direction; with what success, the list of fifty-two asteroids,

-  with their names and the dates of their discovery, will best show.

-  The labours of our indefatigable countryman, Mr. Hind, have been

-  rewarded by the discovery of no less than eight of them.

-

-

-FIRE-BALLS AND SHOOTING STARS.

-

-Humboldt relates, that a friend at Popayan, at an elevation of 5583

-feet above the sea-level, at noon, when the sun was shining brightly

-in a cloudless sky, saw his room lighted up by a fire-ball: he had his

-back towards the window at the time, and on turning round, perceived

-that great part of the path traversed by the fire-ball was still

-illuminated by the brightest radiance. The Germans call these phenomena

-_star-snuff_, from the vulgar notion that the lights in the firmament

-undergo a process of snuffing, or cleaning. Other nations call it _a

-shot or fall of stars_, and the English _star-shoot_. Certain tribes

-of the Orinoco term the pearly drops of dew which cover the beautiful

-leaves of the heliconia _star-spit_. In the Lithuanian mythology, the

-nature and signification of falling stars are embodied under nobler and

-more graceful symbols. The Parcæ, _Werpeja_, weave in heaven for the

-new-born child its thread of fate, attaching each separate thread to

-a star. When death approaches the person, the thread is rent, and the

-star wanes and sinks to the earth.--_Jacob Grimm._

-

-

-THEORY AND EXPERIENCE.

-

-In the perpetual vicissitude of theoretical views, says the author of

-_Giordano Bruno_, “most men see nothing in philosophy but a succession

-of passing meteors; whilst even the grander forms in which she has

-revealed herself share the fate of comets,--bodies that do not rank in

-popular opinion amongst the external and permanent works of nature, but

-are regarded as mere fugitive apparitions of igneous vapour.”

-

-

-METEORITES FROM THE MOON.

-

-The hypothesis of the selenic origin of meteoric stones depends upon

-a number of conditions, the accidental coincidence of which could

-alone convert a possible to an actual fact. The view of the original

-existence of small planetary masses in space is simpler, and at

-the same time more analogous with those entertained concerning the

-formation of other portions of the solar system.

-

-  Diogenes Laertius thought aerolites came from the sun; but Pliny

-  derides this theory. The fall of aerolites in bright sunshine, and

-  when the moon’s disc was invisible, probably led to the idea of

-  sun-stones. Moreover Anaxagoras regarded the sun as “a molten fiery

-  mass;” and Euripides, in Phaëton, terms the sun “a golden mass,”

-  that is to say, a fire-coloured, brightly-shining matter, but not

-  leading to the inference that aerolites are golden sun-stones.

-  The Greek philosophers had four hypotheses as to their origin:

-  telluric, from ascending exhalations; masses of stone raised by

-  hurricanes; a solar origin; and lastly, an origin in the regions of

-  space, as heavenly bodies which had long remained invisible: the

-  last opinion entirely according with that of the present day.

-

-  Chladni states that an Italian physicist, Paolo Maria Terzago,

-  on the occasion of the fall of an aerolite at Milan, in 1660, by

-  which a Franciscan monk was killed, was the first who surmised that

-  aerolites were of selenic origin. Without any previous knowledge

-  of this conjecture, Olbers was led, in 1795 (after the celebrated

-  fall at Siena, June 16th, 1794), to investigate the amount of the

-  initial tangential force that would be required to bring to the

-  earth masses projected from the moon. Olbers, Brandes, and Chaldni

-  thought that “the velocity of 16 to 32 miles, with which fire-balls

-  and shooting-stars entered our atmosphere,” furnished a refutation

-  to the view of their selenic origin. According to Olbers, it would

-  require to reach the earth, setting aside the resistance of the

-  air, an initial velocity of 8292 feet in the second; according to

-  Laplace, 7862; to Biot, 8282; and to Poisson, 7595. Laplace states

-  that this velocity is only five or six times as great as that of

-  a cannon-ball; but Olbers has shown that “with such an initial

-  velocity as 7500 or 8000 feet in a second, meteoric stones would

-  arrive at the surface of our earth with a velocity of only 35,000

-  feet.” But the measured velocity of meteoric stones averages

-  upwards of 114,000 feet to a second; consequently the original

-  velocity of projection from the moon must be almost 110,000 feet,

-  and therefore 14 times greater than Laplace asserted. It must,

-  however, be recollected, that the opinion then so prevalent, of the

-  existence of active volcanoes in the moon, where air and water are

-  absent, has since been abandoned.

-

-  Laplace elsewhere states, that in all probability aerolites “come

-  from the depths of space;” yet he in another passage inclines to

-  the hypothesis of their lunar origin, always, however, assuming

-  that the stones projected from the moon “become satellites of our

-  earth, describing around it more or less eccentric orbits, and thus

-  not reaching its atmosphere until several or even many revolutions

-  have been accomplished.”

-

-  In Syria there is a popular belief that aerolites chiefly fall

-  on clear moonlight nights. The ancients (Pliny tells us) looked

-  for their fall during lunar eclipses.--_Abridged from Humboldt’s

-  Cosmos_, vol. i. (Bohn’s edition).

-

-Dr. Laurence Smith, U.S., accepts the “lunar theory,” and considers

-meteorites to be masses thrown off from the moon, the attractive power

-of which is but one-sixth that of the earth; so that bodies thrown from

-the surface of the moon experience but one sixth the retarding force

-they would have when thrown from the earth’s surface.

-

-  Look again (says Dr. Smith) at the constitution of the meteorite,

-  made up principally of _pure_ iron. It came evidently from some

-  place where there is little or no oxygen. Now the moon has no

-  atmosphere, and no water on its surface. There is no oxygen there.

-  Hurled from the moon, these bodies,--these masses of almost pure

-  iron,--would flame in the sun like polished steel, and on reaching

-  our atmosphere would burn in its oxygen until a black oxide cooled

-  it; and this we find to be the case with all meteorites,--the

-  black colour is only an external covering.

-

-Sir Humphry Davy, from facts contained in his researches on flame,

-in 1817, conceives that the light of meteors depends, not upon the

-ignition of inflammable gases, but upon that of solid bodies; that such

-is their velocity of motion, as to excite sufficient heat for their

-ignition by the compression even of rare air; and that the phenomena of

-falling stars may be explained by regarding them as small incombustible

-bodies moving round the earth in very eccentric orbits, and becoming

-ignited only when they pass with immense rapidity through the upper

-regions of the atmosphere; whilst those meteors which throw down stony

-bodies are, similarly circumstanced, combustible masses.

-

-Masses of iron and nickel, having all the appearance of aerolites or

-meteoric stones, have been discovered in Siberia, at a depth of ten

-metres below the surface of the earth. From the fact, however, that no

-meteoric stones are found in the secondary and tertiary formations, it

-would seem to follow that the phenomena of falling stones did not take

-place till the earth assumed its present conditions.

-

-

-VAST SHOWER OF METEORS.

-

-The most magnificent Shower of Meteors that has ever been known was

-that which fell during the night of November 12th, 1833, commencing

-at nine o’clock in the evening, and continuing till the morning sun

-concealed the meteors from view. This shower extended from Canada to

-the northern boundary of South America, and over a tract of nearly 3000

-miles in width.

-

-

-IMMENSE METEORITE.

-

-Mrs. Somerville mentions a Meteorite which passed within twenty-five

-miles of our planet, and was estimated to weigh 600,000 tons, and to

-move with a velocity of twenty miles in a second. Only a small fragment

-of this immense mass reached the earth. Four instances are recorded

-of persons being killed by their fall. A block of stone fell at Ægos

-Potamos, B.C. 465, as large as two millstones; another at Narni, in

-921, projected like a rock four feet above the surface of the river,

-in which it was seen to fall. The Emperor Jehangire had a sword forged

-from a mass of meteoric iron, which fell in 1620 at Jahlinder in the

-Punjab. Sixteen instances of the fall of stones in the British Isles

-are well authenticated to have occurred since 1620, one of them in

-London. It is very remarkable that no new chemical element has been

-detected in any of the numerous meteorites which have been analysed.

-

-

-NO FOSSIL METEORIC STONES.

-

-It is (says Olbers) a remarkable but hitherto unregarded fact, that

-while shells are found in secondary and tertiary formations, no Fossil

-Meteoric Stones have as yet been discovered. May we conclude from this

-circumstance, that previous to the present and last modification of the

-earth’s surface no meteoric stones fell on it, though at the present

-time it appears probable, from the researches of Schreibers, that 700

-fall annually?[24]

-

-

-THE END OF OUR SYSTEM.

-

-While all the phenomena in the heavens indicate a law of progressive

-creation, in which revolving matter is distributed into suns and

-planets, there are indications in our own system that a period has been

-assigned for its duration, which, sooner or later, it must reach. The

-medium which fills universal space, whether it be a luminiferous ether,

-or arise from the indefinite expansion of planetary atmospheres, must

-retard the bodies which move in it, even were it 360,000 millions of

-times more rare than atmospheric air; and, with its time of revolution

-gradually shortening, the satellite must return to its planet, the

-planet to its sun, and the sun to its primeval nebula. The fate of our

-system, thus deduced from mechanical laws, must be the fate of all

-others. Motion cannot be perpetuated in a resisting medium; and where

-there exist disturbing forces, there must be primarily derangement,

-and ultimately ruin. From the great central mass, heat may again be

-summoned to exhale nebulous matter; chemical forces may again produce

-motion, and motion may again generate systems; but, as in the recurring

-catastrophes which have desolated our earth, the great First Cause must

-preside at the dawn of each cosmical cycle; and, as in the animal races

-which were successively reproduced, new celestial creations of a nobler

-form of beauty and of a higher form of permanence may yet appear in

-the sidereal universe. “Behold, I create new heavens and a new earth,

-and the former shall not be remembered.” “The new heavens and the

-new earth shall remain before me.” “Let us look, then, according to

-this promise, for the new heavens and the new earth, wherein dwelleth

-righteousness.”--_North-British Review_, No. 3.

-

-

-BENEFITS OF GLASS TO MAN.

-

-Cuvier eloquently says: “It could not be expected that those Phœnician

-sailors who saw the sand of the shores of Bætica transformed by fire

-into a transparent Glass, should have at once foreseen that this new

-substance would prolong the pleasures of sight to the old; that it

-would one day assist the astronomer in penetrating the depths of the

-heavens, and in numbering the stars of the Milky Way; that it would

-lay open to the naturalist a miniature world, as populous, as rich in

-wonders as that which alone seemed to have been granted to his senses

-and his contemplation: in fine, that the most simple and direct use

-of it would enable the inhabitants of the coast of the Baltic Sea to

-build palaces more magnificent than those of Tyre and Memphis, and to

-cultivate, almost under the polar circle, the most delicious fruit of

-the torrid zone.”

-

-

-THE GALILEAN TELESCOPE.

-

-Galileo appears to be justly entitled to the honour of having invented

-that form of Telescope which still bears his name; while we must accord

-to John Lippershey, the spectacle-maker of Middleburg, the honour of

-having previously invented the astronomical telescope. The interest

-excited at Venice by Galileo’s invention amounted almost to frenzy.

-On ascending the tower of St. Mark, that he might use one of his

-telescopes without molestation, Galileo was recognised by a crowd in

-the street, who took possession of the wondrous tube, and detained the

-impatient philosopher for several hours, till they had successively

-witnessed its effects. These instruments were soon manufactured in

-great numbers; but were purchased merely as philosophical toys, and

-were carried by travellers into every corner of Europe.

-

-

-WHAT GALILEO FIRST SAW WITH HIS TELESCOPE.

-

-The moon displayed to him her mountain-ranges and her glens, her

-continents and her highlands, now lying in darkness, now brilliant with

-sunshine, and undergoing all those variations of light and shadow which

-the surface of our own globe presents to the alpine traveller or to the

-aeronaut. The four satellites of Jupiter illuminating their planet, and

-suffering eclipses in his shadow, like our own moon; the spots on the

-sun’s disc, proving his rotation round his axis in twenty-five days;

-the crescent phases of Venus, and the triple form or the imperfectly

-developed ring of Saturn,--were the other discoveries in the solar

-system which rewarded the diligence of Galileo. In the starry heavens,

-too, thousands of new worlds were discovered by his telescope; and the

-Pleiades alone, which to the unassisted eye exhibit only _seven_ stars,

-displayed to Galileo no fewer than _forty_.--_North-British Review_,

-No. 3.

-

-  The first telescope “the starry Galileo” constructed with a leaden

-  tube a few inches long, with a spectacle-glass, one convex and one

-  concave, at each of its extremities. It magnified three times.

-  Telescopes were made in London in February 1610, a year after

-  Galileo had completed his own (Rigaud, _On Harriot’s Papers_,

-  1833). They were at first called _cylinders_. The telescopes which

-  Galileo constructed, and others of which he made use for observing

-  Jupiter’s satellites, the phases of Venus, and the solar spots,

-  possessed the gradually-increasing powers of magnifying four,

-  seven, and thirty-two linear diameters; but they never had a higher

-  power.--Arago, in the _Annuaire_ for 1842.

-

-  Clock-work is now applied to the equatorial telescope, so as to

-  allow the observer to follow the course of any star, comet, or

-  planet he may wish to observe continuously, without using his hands

-  for the mechanical motion of the instrument.

-

-

-ANTIQUITY OF TELESCOPES.

-

-Long tubes were certainly employed by Arabian astronomers, and very

-probably also by the Greeks and Romans; the exactness of their

-observations being in some degree attributable to their causing the

-object to be seen through diopters or slits. Abul Hassan speaks very

-distinctly of tubes, to the extremities of which ocular and object

-diopters were attached; and instruments so constructed were used in

-the observatory founded by Hulagu at Meragha. If stars be more easily

-discovered during twilight by means of tubes, and if a star be sooner

-revealed to the naked eye through a tube than without it, the reason

-lies, as Arago has truly observed, in the circumstance that the tube

-conceals a great portion of the disturbing light diffused in the

-atmospheric strata between the star and the eye applied to the tube.

-In like manner, the tube prevents the lateral impression of the faint

-light which the particles of air receive at night from all the other

-stars in the firmament. The intensity of the image and the size of the

-star are apparently augmented.--_Humboldt’s Cosmos_, vol. iii. p. 53.

-

-

-NEWTON’S FIRST REFLECTING TELESCOPE.

-

-The year 1668 may be regarded as the date of the invention of

-Newton’s Reflecting Telescope. Five years previously, James Gregory

-had described the manner of constructing a reflecting telescope with

-two concave specula; but Newton perceived the disadvantages to be so

-great, that, according to his statement, he “found it necessary, before

-attempting any thing in the practice, to alter the design, and place

-the eye-glass at the side of the tube rather than at the middle.” On

-this improved principle Newton constructed his telescope, which was

-examined by Charles II.; it was presented to the Royal Society near the

-end of 1671, and is carefully preserved by that distinguished body,

-with the inscription:

-

-  “THE FIRST REFLECTING TELESCOPE; INVENTED BY SIR ISAAC NEWTON, AND

-  MADE WITH HIS OWN HANDS.”

-

-Sir David Brewster describes this telescope as consisting of a concave

-metallic speculum, the radius of curvature of which was 12-2/3 or

-13 inches, so that “it collected the sun’s rays at the distance of

-6-1/3 inches.” The rays reflected by the speculum were received upon

-a plane metallic speculum inclined 45° to the axis of the tube, so as

-to reflect them to the side of the tube in which there was an aperture

-to receive a small tube with a plano-convex eye-glass whose radius

-was one-twelfth of an inch, by means of which the image formed by

-the speculum was magnified 38 times. Such was the first reflecting

-telescope applied to the heavens; but Sir David Brewster describes

-this instrument as small and ill-made; and fifty years elapsed before

-telescopes of the Newtonian form became useful in astronomy.

-

-

-SIR WILLIAM HERSCHEL’S GREAT TELESCOPE AT SLOUGH.

-

-The plan of this Telescope was intimated by Herschel, through Sir

-Joseph Banks, to George III., who offered to defray the whole expense

-of it; a noble act of liberality, which has never been imitated by

-any other British sovereign. Towards the close of 1785, accordingly,

-Herschel began to construct his reflecting telescope, _forty feet in

-length_, and having a speculum _fully four feet in diameter_. The

-thickness of the speculum, which was uniform in every part, was 3½

-inches, and its weight nearly 2118 pounds; the metal being composed of

-32 copper, and 10·7 of tin: it was the third speculum cast, the two

-previous attempts having failed. The speculum, when not in use, was

-preserved from damp by a tin cover, fitted upon a rim of close-grained

-cloth. The tube of the telescope was 39 ft. 4 in. long, and its width 4

-ft. 10 in.; it was made of iron, and was 3000 lbs. lighter than if it

-had been made of wood. The observer was seated in a suspended movable

-seat at the mouth of the tube, and viewed the image of the object with

-a magnifying lens or eye-piece. The focus of the speculum, or place of

-the image, was within four inches of the lower side of the mouth of the

-tube, and came forward into the air, so that there was space for part

-of the head above the eye, to prevent it from intercepting many of the

-rays going from the object to the mirror. The eye-piece moved in a tube

-carried by a slider directed to the centre of the speculum, and fixed

-on an adjustible foundation at the mouth of the tube. It was completed

-on the 27th August 1789; and _the very first moment_ it was directed to

-the heavens, a new body was added to the solar system, namely, Saturn

-and six of its satellites; and in less than a month after, the seventh

-satellite of Saturn, “an object,” says Sir John Herschel, “of a far

-higher order of difficulty.”--_Abridged from the North-British Review_,

-No. 3.

-

-  This magnificent instrument stood on the lawn in the rear of Sir

-  William Herschel’s house at Slough; and some of our readers, like

-  ourselves, may remember its extraordinary aspect when seen from

-  the Bath coach-road, and the road to Windsor. The difficulty of

-  managing so large an instrument--requiring as it did two assistants

-  in addition to the observer himself and the person employed to note

-  the time--prevented its being much used. Sir John Herschel, in a

-  letter to Mr. Weld, states the entire cost of its construction,

-  4000_l._, was defrayed by George III. In 1839, the woodwork of

-  the telescope being decayed, Sir John Herschel had it cleared

-  away; and piers were erected, on which the tube was placed, _that_

-  being of iron, and so well preserved that, although not more than

-  one-twentieth of an inch thick, when in the horizontal position

-  it contained within all Sir John’s family; and next the two

-  reflectors, the polishing apparatus, and portions of the machinery,

-  to the amount of a great many tons. Sir John attributes this great

-  strength and resistance to the internal structure of the tube, very

-  similar to that patented under the name of corrugated iron-roping.

-  Sir John Herschel also thinks that system of triangular arrangement

-  of the woodwork was upon the principle to which “diagonal bracing”

-  owes its strength.

-

-

-THE EARL OF ROSSE’S GREAT REFLECTING TELESCOPE.

-

-Sir David Brewster has remarked, that “the long interval of half

-a century seems to be the period of hybernation during which the

-telescopic mind rests from its labours in order to acquire strength for

-some great achievement. Fifty years elapsed between the dwarf telescope

-of Newton and the large instruments of Hadley; other fifty years rolled

-on before Sir William Herschel constructed his magnificent telescope;

-and fifty years more passed away before the Earl of Rosse produced

-that colossal instrument which has already achieved such brilliant

-discoveries.”[25]

-

-In the improvement of the Reflecting Telescope, the first object

-has always been to increase the magnifying power and light by the

-construction of as large a mirror as possible; and to this point Lord

-Rosse’s attention was directed as early as 1828, the field of operation

-being at his lordship’s seat, Birr Castle at Parsonstown, about fifty

-miles west of Dublin. For this high branch of scientific inquiry Lord

-Rosse was well fitted by a rare combination of “talent to devise,

-patience to bear disappointment, perseverance, profound mathematical

-knowledge, mechanical skill, and uninterrupted leisure from other

-pursuits;”[26] all these, however, would not have been sufficient, had

-not a great command of money been added; the gigantic telescope we are

-about to describe having cost certainly not less than twelve thousand

-pounds.

-

-  Lord Rosse ground and polished specula fifteen inches, two feet,

-  and three feet in diameter before he commenced the colossal

-  instrument. It is impossible here to detail the admirable

-  contrivances and processes by which he prepared himself for this

-  great work. He first ascertained the most useful combination of

-  metals for specula, both in whiteness, porosity, and hardness,

-  to be copper and tin. Of this compound the reflector was cast in

-  pieces, which were fixed on a bed of zinc and copper,--a species

-  of brass which expanded in the same degree by heat as the pieces

-  of the speculum themselves. They were ground as one body to a true

-  surface, and then polished by machinery moved by a steam-engine.

-  The peculiarities of this mechanism were entirely Lord Rosse’s

-  invention, and the result of close calculation and observation:

-  they were chiefly, placing the speculum with the face upward,

-  regulating the temperature by having it immersed in water, usually

-  at 55° Fahr., and regulating the pressure and velocity. This was

-  found to work a perfect spherical figure in large surfaces with

-  a degree of precision unattainable by the hand; the polisher, by

-  working above and upon the face of the speculum, being enabled

-  to examine the operation as it proceeded without removing the

-  speculum, which, when a ton weight, is no easy matter.

-

-  The contrivance for doing this is very beautiful. The machine is

-  placed in a room at the bottom of a high tower, in the successive

-  floors of which trap-doors can be opened. A mast is elevated on the

-  top of the tower, so that its summit is about ninety feet _above_

-  the speculum. A dial-plate is attached to the top of the mast, and

-  a small plane speculum and eye-piece, with proper adjustments,

-  are so placed that the combination becomes a Newtonian telescope,

-  and the dial-plate the object. The last and most important part

-  of the process of working the speculum, is to give it a _true

-  parabolic figure_, that is, such a figure that each portion of it

-  should reflect the incident ray to the same focus. Lord Rosse’s

-  operations for this purpose consist--1st, of a stroke of the first

-  eccentric, which carries the polisher along _one-third_ of the

-  diameter of the speculum; 2d, a transverse stroke twenty-one times

-  slower, and equal to 0·27 of the same diameter, measured on the

-  edge of the tank, or 1·7 beyond the centre of the polisher; 3d, a

-  rotation of the speculum performed in the same time as thirty-seven

-  of the first strokes; and 4th, a rotation of the polisher in the

-  same direction about sixteen times slower. If these rules are

-  attended to, the machine will give the true parabolic figure to the

-  speculum, whether it be _six inches_ or _three feet in diameter_.

-  In the three-feet speculum, the figure is so true with the whole

-  aperture, that it is thrown out of focus by a motion of less

-  than the _thirtieth of an inch_, “and even with a single lens of

-  one-eighth of an inch focus, giving a power of 2592, the dots on a

-  watch-dial are still in some degree defined.”

-

-Thus was executed the three-feet speculum for the twenty-six-feet

-telescope placed upon the lawn at Parsonstown, which, in 1840, showed

-with powers up to 1000 and even 1600; and which resolved nebulæ into

-stars, and destroyed that symmetry of form in globular nebulæ upon

-which was founded the hypothesis of the gradual condensation of

-nebulous matter into suns and planets.[27]

-

-Scarcely was this instrument out of Lord Rosse’s hands, when he

-resolved to attempt by the same processes to construct another

-reflector, with a speculum _six feet_ in diameter and _fifty feet

-long_! and this magnificent instrument was completed early in 1845.

-The focal length of the speculum is fifty-four feet. It weighs four

-tons, and, with its supports, is seven times as heavy as the four-feet

-speculum of Sir William Herschel. The speculum is placed in one of

-the sides of a cubical wooden box, about eight feet wide, and to the

-opposite end of this box is fastened the tube, which is made of deal

-staves an inch thick, hooped with iron clamp-rings, like a huge cask.

-It carries at its upper end, and in the axis of the tube, a small oval

-speculum, six inches in its lesser diameter.

-

-The tube is about 50 feet long and 8 feet in diameter in the middle,

-and furnished with diaphragms 6½ feet in aperture. The late Dean of Ely

-walked through the tube with an umbrella up.

-

-The telescope is established between two lofty castellated piers 60

-feet high, and is raised to different altitudes by a strong chain-cable

-attached to the top of the tube. This cable passes over a pulley on

-a frame down to a windlass on the ground, which is wrought by two

-assistants. To the frame are attached chain-guys fastened to the

-counterweights; and the telescope is balanced by these counterweights

-suspended by chains, which are fixed to the sides of the tube and pass

-over large iron pulleys. The immense mass of matter weighs about twelve

-tons.

-

-On the eastern pier is a strong semicircle of cast-iron, with which the

-telescope is connected by a racked bar, with friction-rollers attached

-to the tube by wheelwork, so that by means of a handle near the

-eye-piece, the observer can move the telescope along the bar on either

-side of the meridian, to the distance of an hour for an equatorial star.

-

-On the western pier are stairs and galleries. The observing gallery is

-moved along a railway by means of wheels and a winch; and the mechanism

-for raising the galleries to various altitudes is very ingenious.

-Sometimes the galleries, filled with observers, are suspended midway

-between the two piers, over a chasm sixty feet deep.

-

-An excellent description of this immense Telescope at Birr Castle will

-be found in Mr. Weld’s volume of _Vacation Rambles_.

-

-Sir David Brewster thus eloquently sketches the powers of the telescope

-at the close of his able description of the instrument, which we have

-in part quoted from his _Life of Sir Isaac Newton_.

-

-  We have, in the mornings, walked again and again, and ever with

-  new delight, along its mystic tube, and at midnight, with its

-  distinguished architect, pondered over the marvellous sights which

-  it dis-closes,--the satellites and belts and rings of Saturn,--the

-  old and new ring, which is advancing with its crest of waters to

-  the body of the planet,--the rocks, and mountains, and valleys, and

-  extinct volcanoes of the moon,--the crescent of Venus, with its

-  mountainous outline,--the systems of double and triple stars,--the

-  nebulæ and starry clusters of every variety of shape,--and those

-  spiral nebular formations which baffle human comprehension, and

-  constitute the greatest achievement in modern discovery.

-

-The Astronomer Royal, Mr. Airy, alludes to the impression made by

-the enormous light of the telescope,--partly by the modifications

-produced in the appearance of nebulæ already figured, partly by the

-great number of stars seen at a distance from the Milky Way, and

-partly from the prodigious brilliancy of Saturn. The account given by

-another astronomer of the appearance of Jupiter was that it resembled a

-coach-lamp in the telescope; and this well expresses the blaze of light

-which is seen in the instrument.

-

-The Rev. Dr. Scoresby thus records the results of his visits:

-

-  The range opened to us by the great telescope at Birr Castle is

-  best, perhaps, apprehended by the now usual measurement--not of

-  distances in miles, or millions of miles, or diameters of the

-  earth’s orbit, but--of the progress of light in free space. The

-  determination within, no doubt, a small proportion of error of

-  the parallax of a considerable number of the fixed stars yields,

-  according to Mr. Peters, a space betwixt us and the fixed stars of

-  the smallest magnitude, the sixth, ordinarily visible to the naked

-  eye, of 130 years in the flight of light. This information enables

-  us, on the principles of _sounding the heavens_, suggested by Sir

-  W. Herschel, with the photometrical researches on the stars of Dr.

-  Wollaston and others, to carry the estimation of distances, and

-  that by no means on vague assumption, to the limits of space opened

-  out by the most effective telescopes. And from the guidance thus

-  afforded us as to the comparative power of the six feet speculum

-  in the penetration of space as already elucidated, we might fairly

-  assume the fact, that if any other telescope now in use could

-  follow the sun if removed to the remotest visible position, or

-  till its light would require 10,000 years to reach us, the grand

-  instrument at Parsonstown would follow it so far that from 20,000

-  to 25,000 years would be spent in the transmission of its light to

-  the earth. But in the cases of clusters of stars, and of nebulæ

-  exhibiting a mere speck of misty luminosity, from the combined

-  light of perhaps hundreds of thousands of suns, the _penetration_

-  into space, compared with the results of ordinary vision, must

-  be enormous; so that it would not be difficult to show the

-  _probability_ that a million of years, in flight of light, would

-  be requisite, in regard to the most distant, to trace the enormous

-  interval.

-

-

-GIGANTIC TELESCOPES PROPOSED.

-

-Hooke is said to have proposed the use of Telescopes having a length of

-upwards of 10,000 feet (or nearly two miles), in order to see animals

-in the moon! an extravagant expectation which Auzout considered it

-necessary to refute. The Capuchin monk Schyrle von Rheita, who was well

-versed in optics, had already spoken of the speedy practicability of

-constructing telescopes that should magnify 4000 times, by means of

-which the lunar mountains might be accurately laid down.

-

-Optical instruments of such enormous focal lengths remind us of the

-Arabian contrivances of measurement: quadrants with a radius of about

-190 feet, upon whose graduated limb the image of the sun was received

-as in the gnomon, through a small round aperture. Such a quadrant was

-erected at Samarcand, probably constructed after the model of the older

-sextants of Alchokandi, which were about sixty feet in height.

-

-

-LATE INVENTION OF OPTICAL INSTRUMENTS.

-

-A writer in the _North-British Review_, No. 50, considers it strange

-that a variety of facts which must have presented themselves to the

-most careless observer should not have led to the earlier construction

-of Optical Instruments. The ancients, doubtless, must have formed

-metallic articles with concave surfaces, in which the observer could

-not fail to see himself magnified; and if the radius of the concavity

-exceeded twelve inches, twice the focal distance of his eye, he had in

-his hands an extempore reflecting telescope of the Newtonian form, in

-which the concave metal was the speculum, and his eye the eye-glass,

-and which would magnify and bring near him the image of objects nearly

-behind him. Through the spherical drops of water suspended before his

-eye, an attentive observer might have seen magnified some minute body

-placed accidentally in its anterior focus; and in the eyes of fishes

-and quadrupeds which he used for his food, he might have seen, and

-might have extracted, the beautiful lenses which they contain, and

-which he could not fail to regard as the principal agents in the vision

-of the animals to which they belonged. Curiosity might have prompted

-him to look through these remarkable lenses or spheres; and had he

-placed the lens of the smallest minnow, or that of the bird, the sheep,

-or the ox, in or before a circular aperture, he would have produced a

-microscope or microscopes of excellent quality and different magnifying

-powers. No such observations seem, however, to have been made; and even

-after the invention of glass, and its conversion into globular vessels,

-through which, when filled with any fluid, objects are magnified, the

-microscope remained undiscovered.

-

-

-A TRIAD OF CONTEMPORARY ASTRONOMERS.

-

-It is a remarkable fact in the history of astronomy (says Sir

-David Brewster), that three of its most distinguished professors

-were contemporaries. Galileo was the contemporary of Tycho during

-thirty-seven years, and of Kepler during the fifty-nine years

-of his life. Galileo was born seven years before Kepler, and

-survived him nearly the same time. We have not learned that the

-intellectual triumvirate of the age enjoyed any opportunity for mutual

-congratulation. What a privilege would it have been to have contrasted

-the aristocratic dignity of Tycho with the reckless ease of Kepler, and

-the manly and impetuous mien of the Italian sage!--_Brewster’s Life of

-Newton._

-

-

-A PEASANT ASTRONOMER.

-

-At about the same time that Goodricke discovered the variation of

-the remarkable periodical star Algol, or β Persei, one Palitzch, a

-farmer of Prolitz, near Dresden,--a peasant by station, an astronomer

-by nature,--from his familiar acquaintance with the aspect of the

-heavens, was led to notice, among so many thousand stars, Algol,

-as distinguished from the rest by its variation, and ascertained

-its period. The same Palitzch was also the first to re-discover

-the predicted comet of Halley in 1759, which he saw nearly a month

-before any of the astronomers, who, armed with their telescopes, were

-anxiously watching its return. These anecdotes carry us back to the era

-of the Chaldean shepherds.--_Sir John Herschel’s Outlines._

-

-

-SHIRBURN-CASTLE OBSERVATORY.

-

-Lord Macclesfield, the eminent mathematician, who was twelve years

-President of the Royal Society, built at his seat, Shirburn Castle

-in Oxfordshire, an Observatory, about 1739. It stood 100 yards south

-from the castle-gate, and consisted of a bed-chamber, a room for the

-transit, and the third for a mural quadrant. In the possession of

-the Royal Astronomical Society is a curious print representing two

-of Lord Macclesfield’s servants taking observations in the Shirburn

-observatory; they are Thomas Phelps, aged 82, who, from being a

-stable-boy to Lord-Chancellor Macclesfield, rose by his merit and

-genius to be appointed observer. His companion is John Bartlett,

-originally a shepherd, in which station he, by books and observation,

-acquired such a knowledge in computation, and of the heavenly bodies,

-as to induce Lord Macclesfield to appoint him assistant-observer in

-his observatory. Phelps was the person who, on December 23d, 1743,

-discovered the great comet, and made the first observation of it; an

-account of which is entered in the _Philosophical Transactions_, but

-not the name of the observer.

-

-

-LACAILLE’S OBSERVATORY.

-

-Lacaille, who made more observations than all his contemporaries put

-together, and whose researches will have the highest value as long as

-astronomy is cultivated, had an observatory at the Collège Mazarin,

-part of which is now the Palace of the Institute, at Paris.

-

-  For a long time it had been without observer or instruments;

-  under Napoleon’s reign it was demolished. Lacaille never used

-  to illuminate the wires of his instruments. The inner part of

-  his observatory was painted black; he admitted only the faintest

-  light, to enable him to see his pendulum and his paper: his left

-  eye was devoted to the service of looking to the pendulum, whilst

-  his right eye was kept shut. The latter was only employed to look

-  to the telescope, and during the time of observation never opened

-  but for this purpose. Thus the faintest light made him distinguish

-  the wires, and he very seldom felt the necessity of illuminating

-  them. Part of these blackened walls were visible long after the

-  demolition of the observatory, which took place somewhat about

-  1811.--_Professor Mohl._

-

-

-NICETY REQUIRED IN ASTRONOMICAL CALCULATIONS.

-

-In the _Edinburgh Review_, 1850, we find the following illustrations of

-the enormous propagation of minute errors:

-

-  The rod used in measuring a base-line is commonly about ten

-  feet long; and the astronomer may be said truly to apply that

-  very rod to mete the distance of the stars. An error in placing

-  a fine dot which fixes the length of the rod, amounting to

-  one-five-thousandth of an inch (the thickness of a single silken

-  fibre), will amount to an error of 70 feet in the earth’s diameter,

-  of 316 miles in the sun’s distance, and to 65,200,000 miles in

-  that of the nearest fixed star. Secondly, as the astronomer in his

-  observatory has nothing further to do with ascertaining lengths or

-  distances, except by calculation, his whole skill and artifice are

-  exhausted in the measurement of angles; for by these alone spaces

-  inaccessible can be compared. Happily, a ray of light is straight:

-  were it not so (in celestial spaces at least), there would be an

-  end of our astronomy. Now an angle of a second (3600 to a degree)

-  is a subtle thing. It has an apparent breadth utterly invisible to

-  the unassisted eye, unless accompanied with so intense a splendour

-  (_e. g._ in the case of a fixed star) as actually to raise by its

-  effect on the nerve of sight a spurious image having a sensible

-  breadth. A silkworm’s fibre, such as we have mentioned above,

-  subtends an angle of a second at 3½ feet distance; a cricket-ball,

-  2½ inches diameter, must be removed, in order to subtend a second,

-  to 43,000 feet, or about 8 miles, where it would be utterly

-  invisible to the sharpest sight aided even by a telescope of some

-  power. Yet it is on the measure of one single second that the

-  ascertainment of a sensible parallax in any fixed star depends;

-  and an error of one-thousandth of that amount (a quantity still

-  unmeasurable by the most perfect of our instruments) would place

-  the star too far or too near by 200,000,000,000 miles; a space

-  which light requires 118 days to travel.

-

-

-CAN STARS BE SEEN BY DAYLIGHT?

-

-Aristotle maintains that Stars may occasionally be seen in the

-Daylight, from caverns and cisterns, as through tubes. Pliny alludes

-to the same circumstance, and mentions that stars have been most

-distinctly recognised during solar eclipses. Sir John Herschel has

-heard it stated by a celebrated optician, that his attention was first

-drawn to astronomy by the regular appearance, at a certain hour, for

-several successive days, of a considerable star through the shaft of

-a chimney. The chimney-sweepers who have been questioned upon this

-subject agree tolerably well in stating that “they have never seen

-stars by day, but that when observed at night through deep shafts,

-the sky appeared quite near, and the stars larger.” Saussure states

-that stars have been seen with the naked eye in broad daylight, on

-the declivity of Mont Blanc, at an elevation of 12,757 feet, as he

-was assured by several of the alpine guides. The observer must be

-placed entirely in the shade, and have a thick and massive shade above

-his head, else the stronger light of the air will disperse the faint

-image of the stars; these conditions resembling those presented by the

-cisterns of the ancients, and the chimneys above referred to. Humboldt,

-however, questions the accuracy of these evidences, adding that in the

-Cordilleras of Mexico, Quito, and Peru, at elevations of 15,000 or

-16,000 feet above the sea-level, he never could distinguish stars by

-daylight. Yet, under the ethereally pure sky of Cumana, in the plains

-near the sea-shore, Humboldt has frequently been able, after observing

-an eclipse of Jupiter’s satellites, to find the planet again with the

-naked eye, and has most distinctly seen it when the sun’s disc was from

-18° to 20° above the horizon.

-

-

-LOST HEAT OF THE SUN.

-

-By the nature of our atmosphere, we are protected from the influence

-of the full flood of solar heat. The absorption of caloric by the air

-has been calculated at about one-fifth of the whole in passing through

-a column of 6000 feet, estimated near the earth’s surface. And we are

-enabled, knowing the increasing rarity of the upper regions of our

-gaseous envelope, in which the absorption is constantly diminishing,

-to prove that _about one-third of the solar heat is lost_ by vertical

-transmission through the whole extent of our atmosphere.--_J. D.

-Forbes, F.R.S._; _Bakerian Lecture_, 1842.

-

-

-THE LONDON MONUMENT USED AS AN OBSERVATORY.

-

-Soon after the completion of the Monument on Fish Street Hill, by Wren,

-in 1677, it was used by Hooke and other members of the Royal Society

-for astronomical purposes, but abandoned on account of the vibrations

-being too great for the nicety required in their observations. Hence

-arose _the report that the Monument was unsafe_, which has been revived

-in our time; “but,” says Elmes, “its scientific construction may bid

-defiance to the attacks of all but earthquakes for centuries to come.”

-This vibration in lofty columns is not uncommon. Captain Smythe, in his

-_Cycle of Celestial Objects_, tells us, that when taking observations

-on the summit of Pompey’s Pillar, near Alexandria, the mercury was

-sensibly affected by tremor, although the pillar is a solid.

-

-

-

-

-Geology and Paleontology.

-

-

-IDENTITY OF ASTRONOMY AND GEOLOGY.

-

-While the Astronomer is studying the form and condition and structure

-of the planets, in so far as the eye and the telescope can aid him, the

-Geologist is investigating the form and condition and structure of the

-planet to which he belongs; and it is from the analogy of the earth’s

-structure, as thus ascertained, that the astronomer is enabled to form

-any rational conjecture respecting the nature and constitution of the

-other planetary bodies. Astronomy and Geology, therefore, constitute

-the same science--the science of material or inorganic nature.

-

-When the astronomer first surveys the _concavity_ of the celestial

-vault, he finds it studded with luminous bodies differing in magnitude

-and lustre, some moving to the east and others to the west; while by

-far the greater number seem fixed in space; and it is the business of

-astronomers to assign to each of them its proper place and sphere, to

-determine their true distance from the earth, and to arrange them in

-systems throughout the regions of sidereal space.

-

-In like manner, when the geologist surveys the _convexity_ of his

-own globe, he finds its solid covering composed of rocks and beds of

-all shapes and kinds, lying at every possible angle, occupying every

-possible position, and all of them, generally speaking, at the same

-distance from the earth’s centre. Every where we see what was deep

-brought into visible relation with what was superficial--what is old

-with what is new--what preceded life with what followed it.

-

-Thus displayed on the surface of his globe, it becomes the business

-of the geologist to ascertain how these rocks came into their present

-places, to determine their different ages, and to fix the positions

-which they originally occupied, and consequently their different

-distances from the centre or the circumference of the earth. Raised

-from their original bed, the geologist must study the internal forces

-by which they were upheaved, and the agencies by which they were

-indurated; and when he finds that strata of every kind, from the

-primitive granite to the recent tertiary marine mud, have been thus

-brought within his reach, and prepared for his analysis, he reads their

-respective ages in the organic remains which they entomb; he studies

-the manner in which they have perished, and he counts the cycles of

-time and of life which they disclose.--_Abridged from the North-British

-Review_, No. 9.

-

-

-THE GEOLOGY OF ENGLAND

-

-is more interesting than that of other countries, because our island

-is in a great measure an epitome of the globe; and the observer who is

-familiar with our strata, and the fossil remains which they include,

-has not only prepared himself for similar inquiries in other countries,

-but is already, as it were, by anticipation, acquainted with what he is

-to find there.--_Transactions of the Geological Society._

-

-

-PROBABLE ORIGIN OF THE ENGLISH CHANNEL.

-

-The proposed construction of a submarine tunnel across the Straits

-of Dover has led M. Boué, For. Mem. Geol. Soc., to point out the

-probability that the English Channel has not been excavated by

-water-action only; but owes its origin to one of the lines of

-disturbance which have fissured this portion of the earth’s crust:

-and taking this view of the case, the fissure probably still exists,

-being merely filled with comparatively loose material, so as to prove

-a serious obstacle to any attempt made to drive through it a submarine

-tunnel.--_Proceedings of the Geological Society._

-

-

-HOW BOULDERS ARE TRANSPORTED TO GREAT HEIGHTS.

-

-Sir Roderick Murchison has shown that in Russia, when the Dwina is at

-its maximum height, and penetrates into the chinks of its limestone

-banks, when frozen and expanded it causes disruptions of the rock,

-the entanglement of stony fragments in the ice. In remarkable spring

-floods, the stream so expands that in bursting it throws up its icy

-fragments to 15 or 20 feet above the stream; and the waters subsiding,

-these lateral ice-heaps melt away, and leave upon the bank the

-rifled and angular blocks as evidence of the highest ice-mark. In

-Lapland, M. Böhtlingk assures us that he has found _large granitic

-boulders weighing several tons actually entangled and suspended, like

-birds’-nests, in the branches of pine-trees, at heights of 30 or 40

-feet above the summer level of the stream_![28]

-

-

-WHY SEA-SHELLS ARE FOUND AT GREAT HEIGHTS.

-

-The action of subterranean forces in breaking through and elevating

-strata of sedimentary rocks,--of which the coast of Chili, in

-consequence of a great earthquake, furnishes an example,--leads to the

-assumption that the pelagic shells found by MM. Bonpland and Humboldt

-on the ridge of the Andes, at an elevation of more than 15,000 English

-feet, may have been conveyed to so extraordinary a position, not by a

-rising of the ocean, but by the agency of volcanic forces capable of

-elevating into ridges the softened crust of the earth.

-

-

-SAND OF THE SEA AND DESERT.

-

-That sand is an assemblage of small stones may be seen with the eye

-unarmed with art; yet how few are equally aware of the synonymous

-nature of the sand of the sea and of the land! Quartz, in the form of

-sand, covers almost entirely the bottom of the sea. It is spread over

-the banks of rivers, and forms vast plains, even at a very considerable

-elevation above the level of the sea, as the desert of Sahara in

-Africa, of Kobi in Asia, and many others. This quartz is produced, at

-least in part, from the disintegration of the primitive granite rocks.

-The currents of water carry it along, and when it is in very small,

-light, and rounded grains, even the wind transports it from one place

-to another. The hills are thus made to move like waves, and a deluge of

-sand frequently inundates the neighbouring countries:

-

-    “So where o’er wide Numidian wastes extend,

-    Sudden the impetuous hurricanes descend.”--_Addison’s Cato._

-

-To illustrate the trite axiom, that nothing is lost, let us glance at

-the most important use of sand:

-

-  “Quartz in the form of sand,” observes Maltebrun, “furnishes, by

-  fusion, one of the most useful substances we have, namely glass,

-  which, being less hard than the crystals of quartz, can be made

-  equally transparent, and is equally serviceable to our wants and

-  to our pleasures. There it shines in walls of crystal in the

-  palaces of the great, reflecting the charms of a hundred assembled

-  beauties; there, in the hand of the philosopher, it discovers to us

-  the worlds that revolve above us in the immensity of space, and the

-  no less astonishing wonders that we tread beneath our feet.”

-

-

-PEBBLES.

-

-The various heights and situations at which Pebbles are found have

-led to many erroneous conclusions as to the period of changes of the

-earth’s surface. All the banks of rivers and lakes, and the shores of

-the sea, are covered with pebbles, rounded by the waves which have

-rolled them against each other, and which frequently seem to have

-brought them from a distance. There are also similar masses of pebbles

-found at very great elevations, to which the sea appears never to

-have been able to reach. We find them in the Alps at Valorsina, more

-than 6000 feet above the level of the sea; and on the mountain of Bon

-Homme, which is more than 1000 feet higher. There are some places

-little elevated above the level of the sea, which, like the famous

-plain of Crau, in Provence, are entirely paved with pebbles; while in

-Norway, near Quedlia, some mountains of considerable magnitude seem to

-be completely formed of them, and in such a manner that the largest

-pebbles occupy the summit, and their thickness and size diminish as you

-approach the base. We may include in the number of these confused and

-irregular heaps most of the depositions of matter brought by the river

-or sea, and left on the banks, and perhaps even those immense beds of

-sand which cover the centre of Asia and Africa. It is this circumstance

-which renders so uncertain the distinction, which it is nevertheless

-necessary to establish, between alluvial masses created before the

-commencement of history, and those which we see still forming under our

-own eyes.

-

-A charming monograph, entitled “Thoughts on a Pebble,” full of playful

-sentiment and graceful fancy, has been written by the amiable Dr.

-Mantell, the geologist.

-

-

-ELEVATION OF MOUNTAIN-CHAINS.

-

-Professor Ansted, in his _Ancient World_, thus characterises this

-phenomenon:

-

-  These movements, described in a few words, were doubtless going

-  on for many thousands and tens of thousands of revolutions of our

-  planet. They were accompanied also by vast but slow changes of

-  other kinds. The expansive force employed in lifting up, by mighty

-  movements, the northern portion of the continent of Asia, found

-  partial vent; and from partial subaqueous fissures there were

-  poured out the tabular masses of basalt occurring in Central India;

-  while an extensive area of depression in the Indian Ocean, marked

-  by the coral islands of the Laccadives, the Maldives, the great

-  Chagos bank, and some others, were in the course of depression by a

-  counteracting movement.

-

-Hitherto the processes of denudation and of elevation have been so

-far balanced as to preserve a pretty steady proportion of sea and dry

-land during geological ages; but if the internal temperature should

-be so far reduced as to be no longer capable of generating forces of

-expansion sufficient for this elevatory action, while the denuding

-forces should continue to act with unabated energy, the inevitable

-result would be, that every mountain-top would be in time brought low.

-No earthly barrier could declare to the ocean that there its proud

-waves should be stayed. Nothing would stop its ravages till all dry

-land should be laid prostrate, to form the bed over which it would

-continue to roll an uninterrupted sea.

-

-

-THE CHALK FORMATION.

-

-Mr. Horner, F.R.S., among other things in his researches in the Delta,

-considers it extremely probable that every particle of Chalk in the

-world has at some period been circulating in the system of a living

-animal.

-

-

-WEAR OF BUILDING-STONES.

-

-Professor Henry, in an account of testing the marbles used in building

-the Capitol at Washington, states that every flash of lightning

-produces an appreciable amount of nitric acid, which, diffused in

-rain-water, acts on the carbonate of lime; and from specimens subjected

-to actual freezing, it was found that in ten thousand years one inch

-would be worn from the blocks by the action of frost.

-

-  In 1839, a report of the examination of Sandstones, Limestones,

-  and Oolites of Britain was made to the Government, with a view to

-  the selection of the best material for building the new Houses

-  of Parliament. For this purpose, 103 quarries were described, 96

-  buildings in England referred to, many chemical analyses of the

-  stones were given, and a great number of experiments related,

-  showing, among other points, the cohesive power of each stone,

-  and the amount of disintegration apparent, when subjected to

-  Brard’s process. The magnesian limestone, or dolomite of Bolsover

-  Moor, was recommended, and finally adopted for the Houses; but

-  the selection does not appear to have been so successful as might

-  have been expected from the skill and labour of the investigation.

-  It may be interesting to add, that the publication of the above

-  Report (for which see _Year-Book of Facts_, 1840, pp. 78-80)

-  occasioned Mr. John Mallcott to remark in the _Times_ journal,

-  “that all stone made use of in the immediate neighbourhood of its

-  own quarries is more likely to endure that atmosphere than if it

-  be removed therefrom, though only thirty or forty miles:” and the

-  lapse of comparatively few years has proved the soundness of this

-  observation.[29]

-

-

-PHENOMENA OF GLACIERS ILLUSTRATED.

-

-Professor Tyndall, being desirous of investigating some of the

-phenomena presented by the large masses of mountain-ice,--those frozen

-rivers called Glaciers,--devised the plan of sending a destructive

-agent into the midst of a mass of ice, so as to break down its

-structure in the interior, in order to see if this method would reveal

-any thing of its internal constitution. Taking advantage of the bright

-weather of 1857, he concentrated a beam of sunlight by a condensing

-lens, so as to form the focus of the sun’s rays in the midst of a mass

-of ice. A portion of the ice was melted, but the surrounding parts

-shone out as brilliant stars, produced by the reflection of the faces

-of the crystalline structure. On examining these brilliant portions

-with a lens, Professor Tyndall discovered that the structure of the ice

-had been broken down in symmetrical forms of great beauty, presenting

-minute stars, surrounded by six petals, forming a beautiful flower, the

-plane being always parallel to the plane of congelation of the ice.

-He then prepared a piece of ice, by making both its surfaces smooth

-and parallel to each other. He concentrated in the centre of the ice

-the rays of heat from the electric light; and then, placing the piece

-of ice in the electric microscope, the disc revealed these beautiful

-ice-flowers.

-

-A mass of ice was crushed into fragments; the small fragments were then

-placed in a cup of wood; a hollow wooden die, somewhat smaller than the

-cup, was then pressed into the cup of ice-fragments by the pressure of

-a hydraulic press, and the ice-fragments were immediately united into

-a compact cup of nearly transparent ice. This pressure of fragments

-of ice into a solid mass explains the formation of the glaciers and

-their origin. They are composed of particles of ice or snow; as they

-descend the sides of the mountain, the pressure of the snow becomes

-sufficiently great to compress the mass into solid ice, until it

-becomes so great as to form the beautiful blue ice of the glaciers.

-This compression, however, will not form the solid mass unless the

-temperature of the ice be near that of freezing water. To prove this,

-the lecturer cooled a mass of ice, by wrapping it in a piece of tinfoil

-and exposing it for some time to a bath of the ethereal solution of

-solidified carbonic-acid gas, the coldest freezing mixture known. This

-cooled mass of ice was crushed to fragments, and submitted to the same

-pressure which the other fragments had been exposed to without cohering

-in the slightest degree.--_Lecture at the Royal Institution_, 1858.

-

-

-ANTIQUITY OF GLACIERS.

-

-The importance of glacier agency in the past as well as the present

-condition of the earth, is undoubtedly very great. One of our most

-accomplished and ingenious geologists has, indeed, carried back the

-existence of Glaciers to an epoch of dim antiquity, even in the

-reckoning of that science whose chronology is counted in millions of

-years. Professor Ramsay has shown ground for believing that in the

-fragments of rock that go to make up the conglomerates of the Permian

-strata, intermediate between the Old and the New Red Sandstone, there

-is still preserved a record of the action of ice, either in glaciers

-or floating icebergs, before those strata were consolidated.--_Saturday

-Review_, No. 142.

-

-

-FLOW OF THE MER DE GLACE.

-

-Michel Devouasson of Chamouni fell into a crevasse on the Glacier

-of Talefre, a feeder of the Mer de Glace, on the 29th of July 1836,

-and after a severe struggle extricated himself, leaving his knapsack

-below. The identical knapsack reappeared in July 1846, at a spot on

-the surface of the glacier _four thousand three hundred_ feet from

-the place where it was lost, as ascertained by Professor Forbes, who

-himself collected the fragments; thus indicating the rate of flow of

-the icy river in the intervening ten years.--_Quarterly Review_, No.

-202.

-

-

-THE ALLUVIAL LAND OF EGYPT: ANCIENT POTTERY.

-

-Mr. L. Horner, in his recent researches near Cairo, with the view of

-throwing light upon the geological history of the alluvial land of

-Egypt, obtained from the lowest part of the boring of the sediment at

-the colossal statue of Rameses, at a depth of thirty-nine feet, this

-curious relic of the ancient world; the boring instrument bringing up

-a fragment of pottery about an inch square and a quarter of an inch in

-thickness--the two surfaces being of a brick-red colour, the interior

-dark gray. According to Mr. Horner’s deductions, this fragment, having

-been found at a depth of 39 feet (if there be no fallacy in his

-reasoning), must be held to be a record of the existence of man 13,375

-years before A.D. 1858, reckoning by the calculated rate of increase of

-three inches and a half of alluvium in a century--11,517 years before

-the Christian era, and 7625 before the beginning assigned by Lepsius

-to the reign of Menos, the founder of Memphis. Moreover it proves in

-his opinion, that man had already reached a state of civilisation, so

-far at least as to be able to fashion clay into vessels, and to know

-how to harden it by the action of strong heat. This calculation is

-supported by the Chevalier Bunsen, who is of opinion that the first

-epochs of the history of the human race demand at the least a period

-of 20,000 years before our era as a fair starting-point in the earth’s

-history.--_Proceedings of Royal Soc._, 1858.

-

-  Upon this theory, a Correspondent, “An Old Indigo-Planter,” writes

-  to the _Athenæum_, No. 1509, the following suggestive note: “Having

-  lived many years on the banks of the Ganges, I have seen the stream

-  encroach on a village, undermining the bank where it stood, and

-  deposit, as a natural result, bricks, pottery, &c. in the bottom

-  of the stream. On one occasion, I am certain that the depth of

-  the stream where the bank was breaking was above 40 feet; yet in

-  three years the current of the river drifted so much, that a fresh

-  deposit of soil took place over the _débris_ of the village, and

-  the earth was raised to a level with the old bank. Now had our

-  traveller then obtained a bit of pottery from where it had lain for

-  only three years, could he reasonably draw the inference that it

-  had been made 13,000 years before?”

-

-

-SUCCESSIVE CHANGES OF THE TEMPLE OF SERAPIS.

-

-The Temple of Serapis at Puzzuoli, near Naples, is perhaps, of all

-the structures raised by the hands of man, the one which affords most

-instruction to a geologist. It has not only undergone a wonderful

-succession of changes in past time, but is still undergoing changes

-of condition. This edifice was exhumed in 1750 from the eastern shore

-of the Bay of Baiæ, consisting partly of strata containing marine

-shells with fragments of pottery and sculpture, and partly of volcanic

-matter of sub-aerial origin. Various theories were proposed in the

-last century to explain the perforations and attached animals observed

-on the middle zone of the three erect marble columns until recently

-standing; Goethe, among the rest, suggesting that a lagoon had once

-existed in the vestibule of the temple, filled during a temporary

-incursion of the sea with salt water, and that marine mollusca and

-annelids flourished for years in this lagoon at twelve feet or more

-above the sea-level.

-

-This hypothesis was advanced at a time when almost any amount of

-fluctuation in the level of the sea was thought more probable than

-the slightest alteration in the level of the solid land. In 1807 the

-architect Niccolini observed that the pavement of the temple was dry,

-except when a violent south wind was blowing; whereas, on revisiting

-the temple fifteen years later, he found the pavement covered by salt

-water twice every day at high tide. From measurements made from 1822

-to 1838, and thence to 1845, he inferred that the sea was gaining

-annually upon the floor of the temple at the rate of about one-third

-of an inch during the first period, and about three-fourths of an inch

-during the second. Mr. Smith of Jordan Hill, from his visits in 1819

-and 1845, found an average rise of about an inch annually, which was

-in accordance with visits made by Mr. Babbage in 1828, and Professor

-James Forbes in 1826 and 1843. In 1852 Signor Scaecchi, at the request

-of Sir Charles Lyell, compared the depth of water on the pavement with

-its level taken by him in 1839, and found that it had gained only 4½

-inches in thirteen years, and was not so deep as when MM. Niccolini

-and Smith measured it in 1845; from which he inferred that after 1845

-the downward movement of the land had ceased, and before 1852 had been

-converted into an upward movement.

-

-Arago and others maintained that the surface on which the temple

-stands has been depressed, has _remained under the sea, and has again

-been elevated_. Russager, however, contends that there is nothing in

-the vicinity of the temple, or in the temple itself, to justify this

-bold hypothesis. Every thing leads to the belief that the temple has

-remained unchanged in the position in which it was originally built;

-but that the sea rose, surrounded it to a height of at least twelve

-feet, and again retired; but the elevated position of the sea continued

-sufficiently long to admit of the animals boring the pillars. This view

-can even be proved historically; for Niccolini, in a memoir published

-in 1840, gives the heights of the level of the sea in the Bay of

-Naples for a period of 1900 years, and has with much acuteness proved

-his assertions historically. The correctness of Russager’s opinion,

-he states, can be demonstrated and reduced to figures by means of the

-dates collected by Niccolini.--See _Jameson’s Journal_, No. 58.

-

-At the present time the floor is always covered with sea-water. On the

-whole, there is little doubt that the ground has sunk upwards of two

-feet during the last half-century. This gradual subsidence confirms

-in a remarkable manner Mr. Babbage’s conclusions--drawn from the

-calcareous incrustations formed by the hot springs on the walls of the

-building and from the ancient lines of the water-level at the base of

-the three columns--that the original subsidence was not sudden, but

-slow and by successive movements.

-

-Sir Charles Lyell (who, in his _Principles of Geology_, has given a

-detailed account of the several upfillings of the temple) considers

-that when the mosaic pavement was re-constructed, the floor of the

-building must have stood about twelve feet above the level of 1838 (or

-about 11½ feet above the level of the sea), and that it had sunk about

-nineteen feet below that level before it was elevated by the eruption

-of Monte Nuovo.

-

-We regret to add, that the columns of the temple are no longer in

-the position in which they served so many years as a species of

-self-registering hydrometer: the materials have been newly arranged,

-and thus has been torn as it were from history a page which can never

-be replaced.

-

-

-THE GROTTO DEL CANE.

-

-This “Dog Grotto” has been so much cited for its stratum of

-carbonic-acid gas covering the floor, that all geological travellers

-who visit Naples feel an interest in seeing the wonder.

-

-This cavern was known to Pliny. It is continually exhaling from its

-sides and floor volumes of steam mixed with carbonic-acid gas; but the

-latter, from its greater specific gravity, accumulates at the bottom,

-and flows over the step of the door. The upper part of the cave,

-therefore, is free from the gas, while the floor is completely covered

-by it. Addison, on his visit, made some interesting experiments. He

-found that a pistol could not be fired at the bottom; and that on

-laying a train of gunpowder and igniting it on the outside of the

-cavern, the carbonic-acid gas “could not intercept the train of fire

-when it once began flashing, nor hinder it from running to the very

-end.” He found that a viper was nine minutes in dying on the first

-trial, and ten minutes on the second; this increased vitality being,

-in his opinion, attributable to the stock of air which it had inhaled

-after the first trial. Dr. Daubeny found that phosphorus would continue

-lighted at about two feet above the bottom; that a sulphur-match went

-out in a few minutes above it, and a wax-taper at a still higher level.

-The keeper of the cavern has a dog, upon which he shows the effects of

-the gas, which, however, are quite as well, if not better, seen in a

-torch, a lighted candle, or a pistol.

-

-“Unfortunately,” says Professor Silliman, “like some other grottoes,

-the enchantment of the ‘Dog Grotto’ disappears on a near view.” It is a

-little hole dug artificially in the side of a hill facing Lake Agnano:

-it is scarcely high enough for a person to stand upright in, and the

-aperture is closed by a door. Into this narrow cell a poor little dog

-is very unwillingly dragged and placed in a depression of the floor,

-where he is soon narcotised by the carbonic acid. The earth is warm to

-the hand, and the gas given out is very constant.

-

-

-THE WATERS OF THE GLOBE GRADUALLY DECREASING.

-

-This was maintained by M. Bory Saint Vincent, because the vast deserts

-of sand, mixed up with the salt and remains of marine animals, of which

-the surface of the globe is partly composed, were formerly inland seas,

-which have insensibly become dry. The Caspian, the Dead Sea, the Lake

-Baikal, &c. will become dry in their turn also, when their beds will

-be sandy deserts. The inland seas, whether they have only one outlet,

-as the Mediterranean, the Red Sea, the Baltic, &c., or whether they

-have several, as the Gulf of Mexico, the seas of O’Kotsk, of Japan,

-China, &c., will at some future time cease to communicate with the

-great basins of the ocean; they will become inland seas, true Caspians,

-and in due time will become likewise dry. On all sides the waters

-of rivers are seen to carry forward in their course the soil of the

-continent. Alluvial lands, deltas, banks of sand, form themselves near

-the coasts, and in the directions of the currents; madreporic animals

-lay the foundations of new lands; and while the straits become closed,

-while the depths of the sea fill up, the level of the sea, which it

-would seem natural should become higher, is sensibly lower. There is,

-therefore, an actual diminution of liquid matter.

-

-

-THE SALT LAKE OF UTAH.

-

-Lieutenant Gunnison, who has surveyed the great basin of the Salt

-Lake, states the water to be about one-third salt, which it yields

-on boiling. Its density is considerably greater than that of the Red

-Sea. One can hardly get the whole body below the surface: in a sitting

-position the head and shoulders will remain above the water, such is

-the strength of the brine; and on coming to the shore the body is

-covered with an incrustation of salt in fine crystals. During summer

-the lake throws on shore abundance of salt, while in winter it throws

-up Glauber salt plentifully. “The reason of this,” says Lieutenant

-Gunnison, “is left for the scientific to judge, and also what becomes

-of the enormous amount of fresh water poured into it by three or four

-large rivers,--Jordan, Bear, and Weber,--as there is no visible effect.”

-

-

-FORCE OF RUNNING WATER.

-

-It has been proved by experiment that the rapidity at the bottom

-of a stream is every where less than in any other part of it, and

-is greatest at the surface. Also, that in the middle of the stream

-the particles at the top move swifter than those at the sides. This

-slowness of the lowest and side currents is produced by friction; and

-when the rapidity is sufficiently great, the soil composing the sides

-and bottom gives way. If the water flows at the rate of three inches

-per second, it will tear up fine clay; six inches per second, fine

-sand; twelve inches per second, fine gravel; and three feet per second,

-stones the size of an egg.--_Sir Charles Lyell._

-

-

-THE ARTESIAN WELL OF GRENELLE AT PARIS.

-

-M. Peligot has ascertained that the Water of the Artesian Well of

-Grenelle contains not the least trace of air. Subterranean waters ought

-therefore to be _aerated_ before being used as aliment. Accordingly, at

-Grenelle, has been constructed a tower, from the top of which the water

-descends in innumerable threads, so as to present as much surface as

-possible to the air.

-

-The boring of this Well by the Messrs. Mulot occupied seven years, one

-month, twenty-six days, to the depth of 1794½ English feet, or 194½

-feet below the depth at which M. Elie de Beaumont foretold that water

-would be found. The sound, or borer, weighed 20,000 lb., and was treble

-the height of that of the dome of the Hôpital des Invalides at Paris.

-In May 1837, when the bore had reached 1246 feet 8 inches, the great

-chisel and 262 feet of rods fell to the bottom; and although these

-weighed five tons, M. Mulot tapped a screw on the head of the rods, and

-thus, connecting another length to them, after fifteen months’ labour,

-drew up the chisel. On another occasion, this chisel having been raised

-with great force, sank at one stroke 85 feet 3 inches into the chalk!

-

-  The depth of the Grenelle Well is nearly four times the height of

-  Strasburg Cathedral; more than six times the height of the Hôpital

-  des Invalides at Paris; more than four times the height of St.

-  Peter’s at Rome; nearly four times and a half the height of St.

-  Paul’s, and nine times the height of the Monument, London. Lastly,

-  suppose all the above edifices to be piled one upon each other,

-  from the base-line of the Well of Grenelle, and they would but

-  reach within 11½ feet of its surface.

-

-  MM. Elie de Beaumont and Arago never for a moment doubted the final

-  success of the work; their confidence being based on analogy, and

-  on a complete acquaintance with the geological structure of the

-  Paris basin, which is identical with that of the London basin

-  beneath the London clay.

-

-  In the duchy of Luxembourg is a well the depth of which surpasses

-  all others of the kind. It is upwards of 1000 feet more than that

-  of Grenelle near Paris.

-

-

-HOW THE GULF-STREAM REGULATES THE TEMPERATURE OF LONDON.

-

-Great Britain is almost exactly under the same latitude as Labrador, a

-region of ice and snow. Apparently, the chief cause of the remarkable

-difference between the two climates arises from the action of the great

-oceanic Gulf-Stream, whereby this country is kept constantly encircled

-with waters warmed by a West-Indian sun.

-

-  Were it not for this unceasing current from tropical seas, London,

-  instead of its present moderate average winter temperature of

-  6° above the freezing-point, might for many months annually be

-  ice-bound by a settled cold of 10° to 30° below that point, and

-  have its pleasant summer months replaced by a season so short

-  as not to allow corn to ripen, or only an alpine vegetation to

-  flourish.

-

-  Nor are we without evidence afforded by animal life of a greater

-  cold having prevailed in this country at a late geological period.

-  One case in particular occurs within eighty miles of London, at the

-  village of Chillesford, near Woodbridge, where, in a bed of clayey

-  sand of an age but little (geologically speaking) anterior to the

-  London gravel, Mr. Prestwich has found a group of fossil shells

-  in greater part identical with species now living in the seas of

-  Greenland and of similar latitudes, and which must evidently, from

-  their perfect condition and natural position, have existed in the

-  place where they are now met with.--_Lectures on the Geology of

-  Clapham, &c. by Joseph Prestwich, A.R.S., F.G.S._

-

-

-SOLVENT ACTION OF COMMON SALT AT HIGH TEMPERATURES.

-

-Forchhammer, after a long series of experiments, has come to the

-conclusion that Common Salt at high temperatures, such as prevailed at

-earlier periods of the earth’s history, acted as a general solvent,

-similarly to water at common temperatures. The amount of common salt

-in the earth would suffice to cover its whole surface with a crust ten

-feet in thickness.

-

-

-FREEZING CAVERN IN RUSSIA.

-

-This famous Cavern, at Ithetz Kaya-Zastchita, in the Steppes of the

-Kirghis, is employed by the inhabitants as a cellar. It has the very

-remarkable property of being so intensely cold during the hottest

-summers as to be then filled with ice, which disappearing with cold

-weather, is entirely gone in winter, when all the country is clad

-in snow. The roof is hung with ever-dripping solid icicles, and the

-floor may be called a stalagmite of ice and frozen earth. “If,” says

-Sir R. Murchison, “as we were assured, _the cold is greatest when the

-external air is hottest and driest_, that the fall of rain and a moist

-atmosphere produce some diminution of the cold in the cave, and that

-upon the setting-in of winter the ice disappears entirely,--then indeed

-the problem is very curious.” The peasants assert that in winter they

-could sleep in the cave without their sheepskins.

-

-

-INTERIOR TEMPERATURE OF THE EARTH: CENTRAL HEAT.

-

-By the observed temperature of mines, and that at the bottom of

-artesian wells, it has been established that the rate at which such

-temperature increases as we descend varies considerably in different

-localities, where the depths are comparatively small; but where the

-depths are great, we find a much nearer approximation to a common

-rate of increase, which, as determined by the best observation in the

-deepest mines, shafts, and artesian wells in Western Europe, is very

-nearly 1° F. _for an increase in depth of fifty feet_.--_W. Hopkins,

-M.A., F.R.S._

-

-Humboldt states that, according to tolerably coincident experiments in

-artesian wells, it has been shown that the heat increases on an average

-about 1° for every 54·5 feet. If this increase can be reduced to

-arithmetical relations, it will follow that a stratum of granite would

-be in a state of fusion at a depth of nearly twenty-one geographical

-miles, or between four and five times the elevation of the highest

-summit of the Himalaya.

-

-The following is the opinion of Professor Silliman:

-

-  That the whole interior portion of the earth, or at least a great

-  part of it, is an ocean of melted rock, agitated by violent winds,

-  though I dare not affirm it, is still rendered highly probable by

-  the phenomena of volcanoes. The facts connected with their eruption

-  have been ascertained and placed beyond a doubt. How, then, are

-  they to be accounted for? The theory prevalent some years since,

-  that they are caused by the combustion of immense coal-beds, is

-  puerile and now entirely abandoned. All the coal in the world could

-  not afford fuel enough for one of the tremendous eruptions of

-  Vesuvius.

-

-This observed increase of temperature in descending beneath the earth’s

-surface suggested the notion of a central incandescent nucleus still

-remaining in a state of fluidity from its elevated temperature. Hence

-the theory that the whole mass of the earth was formerly a molten

-fluid mass, the exterior portion of which, to some unknown depth, has

-assumed its present solidity by the radiation of heat into surrounding

-space, and its consequent refrigeration.

-

-The mathematical solution of this problem of Central Heat, assuming

-such heat to exist, tells us that though the central portion of the

-earth may consist of a mass of molten matter, the temperature of its

-surface is not thereby increased by more than the small fraction of

-a degree. Poisson has calculated that it would require _a thousand

-millions of centuries_ to reduce this fraction to a degree by half its

-present amount, supposing always the external conditions to remain

-unaltered. In such cases, the superficial temperature of the earth may,

-in fact, be considered to have approximated so near to its ultimate

-limit that it can be subject to no further sensible change.

-

-

-DISAPPEARANCE OF VOLCANIC ISLANDS.

-

-Many of the Volcanic Islands thrown up above the sea-level soon

-disappear, because the lavas and conglomerates of which they are formed

-spread over flatter surfaces, through the weight of the incumbent

-fluid; and the constant levelling process goes on below the sea by the

-action of tides and currents. Such islands as have effectually resisted

-this action are found to possess a solid framework of lava, supporting

-or defending the loose fragmentary materials.

-

-  Among the most celebrated of these phenomena in our times may be

-  mentioned the Isle of Sabrina, which rose off the coast of St.

-  Michael’s in 1811, attained a circumference of one mile and a

-  height of 300 feet, and disappeared in less than eight months; in

-  the following year there were eighty fathoms of water in its place.

-  In July 1831 appeared Graham’s Island off the coast of Sicily,

-  which attained a mile in circumference and 150 or 160 feet in

-  height; its formation much resembled that of Sabrina.

-

-The line of ancient subterranean fire which we trace on the

-Mediterranean coasts has had a strange attestation in Graham’s Island,

-which is also described as a volcano suddenly bursting forth in the mid

-sea between Sicily and Africa; burning for several weeks, and throwing

-up an isle, or crater-cone of scoriæ and ashes, which had scarcely been

-named before it was again lost by subsidence beneath the sea, leaving

-only a shoal-bank to attest this strange submarine breach in the

-earth’s crust, which thus mingled fire and water in one common action.

-

-Floating islands are not very rare: in 1827, one was seen twenty

-leagues to the east of the Azores; it was three leagues in width, and

-covered with volcanic products, sugar-canes, straw, and pieces of wood.

-

-

-PERPETUAL FIRE.

-

-Not far from the Deliktash, on the side of a mountain in Lycia, is the

-Perpetual Fire described some forty years since by Captain Beaufort.

-It was found by Lieutenant Spratt and Professor Forbes, thirty years

-later, as brilliant as ever, and somewhat increased; for besides the

-large flame in the corner of the ruins described by Beaufort, there

-were small jets issuing from crevices in the side of the crater-like

-cavity five or six feet deep. At the bottom was a shallow pool of

-sulphureous and turbid water, regarded by the Turks as a sovereign

-remedy for all skin complaints. The soot deposited from the flames was

-held to be efficacious for sore eyelids, and valued as a dye for the

-eyebrows. This phenomenon is described by Pliny as the flame of the

-Lycian Chimera.

-

-

-ARTESIAN FIRE-SPRINGS IN CHINA.

-

-According to the statement of the missionary Imbert, the

-Fire-Springs, “Ho-tsing” of the Chinese, which are sunk to obtain a

-carburetted-hydrogen gas for salt-boiling, far exceed our artesian

-springs in depth. These springs are very commonly more than 2000 feet

-deep; and a spring of continued flow was found to be 3197 feet deep.

-This natural gas has been used in the Chinese province Tse-tschuan for

-several thousand years; and “portable gas” (in bamboo-canes) has for

-ages been used in the city of Khiung-tscheu. More recently, in the

-village of Fredonia, in the United States, such gas has been used both

-for cooking and for illumination.

-

-

-VOLCANIC ACTION THE GREAT AGENT OF GEOLOGICAL CHANGE.

-

-  Mr. James Nasmyth observes, that “the floods of molten lava which

-  volcanoes eject are nothing less than remaining portions of what

-  was once the condition of the entire globe when in the igneous

-  state of its early physical history,--no one knows how many years

-  ago!

-

-  “When we behold the glow and feel the heat of molten lava, how

-  vastly does it add to the interest of the sight when we consider

-  that the heat we feel and the light we see are the residue of the

-  once universal condition of our entire globe, on whose _cooled

-  surface_ we _now_ live and have our being! But so it is; for if

-  there be one great fact which geological research has established

-  beyond all doubt, it is that we reside on the cooled surface of

-  what was once a molten globe, and that all the phenomena which

-  geology has brought to light can be most satisfactorily traced

-  to the successive changes incidental to its gradual cooling and

-  contraction.

-

-  “That the influx of the sea into the yet hot and molten interior of

-  the globe may occasionally occur, and enhance and vary the violence

-  of the phenomenon of volcanic action, there can be little doubt;

-  but the action of water in such cases is only _secondary_. But for

-  the pre-existing high temperature of the interior of the earth, the

-  influx of water would produce no such discharges of molten lava as

-  generally characterise volcanic eruptions. Molten lava is therefore

-  a true vestige of the Natural History of the Creation.”

-

-

-THE SNOW-CAPPED VOLCANO.

-

-It is but rarely that the elastic forces at work within the interior of

-our globe have succeeded in breaking through the spiral domes which,

-resplendent in the brightness of eternal snow, crown the summits of the

-Cordilleras; and even where these subterranean forces have opened a

-permanent communication with the atmosphere, through circular craters

-or long fissures, they rarely send forth currents of lava, but merely

-eject ignited scoriæ, steam, sulphuretted hydrogen gas, and jets of

-carbonic acid.--_Humboldt’s Cosmos_, vol. i.

-

-

-TRAVELS OF VOLCANIC DUST.

-

-On the 2d of September 1845, a quantity of Volcanic Dust fell in the

-Orkney Islands, which was supposed to have originated in an eruption of

-Hecla, in Iceland. It was subsequently ascertained that an eruption of

-that volcano took place on the morning of the above day (September 2),

-so as to leave no doubt of the accuracy of the conclusion. The dust had

-thus travelled about 600 miles!

-

-

-GREAT ERUPTIONS OF VESUVIUS.

-

-In the great eruption of Vesuvius, in August 1779, which Sir William

-Hamilton witnessed from his villa at Pausilippo in the bay of Naples,

-the volcano sent up white sulphureous smoke resembling bales of cotton,

-exceeding the height and size of the mountain itself at least four

-times; and in the midst of this vast pile of smoke, stones, scoriæ,

-and ashes were thrown up not less than 2000 feet. Next day a fountain

-of fire shot up with such height and brilliancy that the smallest

-objects could be clearly distinguished at any place within six miles

-or more of Vesuvius. But on the following day a more stupendous column

-of fire rose three times the height of Vesuvius (3700 feet), or more

-than two miles high. Among the huge fragments of lava thrown out during

-this eruption was a block 108 feet in circumference and 17 feet high,

-another block 66 feet in circumference and 19 feet high, and another 16

-feet high and 92 feet in circumference, besides thousands of smaller

-fragments. Sir William Hamilton suggests that from a scene of the above

-kind the ancient poets took their ideas of the giants waging war with

-Jupiter.

-

-The eruption of June 1794, which destroyed the greater part of the

-town of Torre del Greco, was, however, the most violent that has been

-recorded after the two great eruptions of 79 and 1631.

-

-

-EARTH-WAVES.

-

-The waves of an earthquake have been represented in their progress,

-and their propagation, through rocks of different density and

-elasticity; and the causes of the rapidity of propagation, and its

-diminution by the refraction, reflection, and interference of the

-oscillations have been mathematically investigated. Air, water, and

-earth waves follow the same laws which are recognised by the theory of

-motion, at all events in space; but the earth-waves are accompanied

-in their destructive action by discharges of elastic vapours, and

-of gases, and mixtures of pyroxene crystals, carbon, and infusorial

-animalcules with silicious shields. The more terrific effects are,

-however, when the earth-waves are accompanied by cleavage; and, as in

-the earthquake of Riobamba, when fissures alternately opened and closed

-again, so that men saved themselves by extending both arms, in order to

-prevent their sinking.

-

-As a remarkable example of the closing of a fissure, Humboldt mentions

-that, during the celebrated earthquake in 1851, in the Neapolitan

-province of Basilicata, a hen was found caught by both feet in the

-street-pavement of Barile, near Melfi.

-

-Mr. Hopkins has very correctly shown theoretically that the fissures

-produced by earthquakes are very instructive as regards the formation

-of veins and the phenomenon of dislocation, the more recent vein

-displacing the older formation.

-

-

-RUMBLINGS OF EARTHQUAKES.

-

-When the great earthquake of Coseguina, in Nicaragua, took place,

-January 23, 1835, the subterranean noise--the sonorous waves in the

-earth--was heard at the same time on the island of Jamaica and on the

-plateau of Bogota, 8740 feet above the sea, at a greater distance than

-from Algiers to London. In the eruptions of the volcano on the island

-of St. Vincent, April 30, 1812, at 2 A.M., a noise like the report of

-cannons was heard, without any sensible concussion of the earth, over a

-space of 160,000 geographical square miles. There have also been heard

-subterranean thunderings for two years without earthquakes.

-

-

-HOW TO MEASURE AN EARTHQUAKE-SHOCK.

-

-A new instrument (the Seismometer) invented for this purpose by

-M. Kreil, of Vienna, consists of a pendulum oscillating in every

-direction, but unable to turn round on its point of suspension; and

-bearing at its extremity a cylinder, which, by means of mechanism

-within it, turns on its vertical axis once in twenty-four hours. Next

-to the pendulum stands a rod bearing a narrow elastic arm, which

-slightly presses the extremity of a lead-pencil against the surface

-of the cylinder. As long as the pendulum is quiet, the pencil traces

-an uninterrupted line on the surface of the cylinder; but as soon as

-it oscillates, this line becomes interrupted and irregular, and these

-irregularities indicate the time of the commencement of an earthquake,

-together with its duration and intensity.[30]

-

-Elastic fluids are doubtless the cause of the slight and perfectly

-harmless trembling of the earth’s surface, which has often continued

-for several days. The focus of this destructive agent, the seat of

-the moving force, lies far below the earth’s surface; but we know as

-little of the extent of this depth as we know of the chemical nature

-of these vapours that are so highly compressed. At the edges of two

-craters,--Vesuvius and the towering rock which projects beyond the

-great abyss of Pichincha, near Quito,--Humboldt has felt periodic

-and very regular shocks of earthquakes, on each occasion from twenty

-to thirty seconds before the burning scoriæ or gases were erupted.

-The intensity of the shocks was increased in proportion to the time

-intervening between them, and consequently to the length of time in

-which the vapours were accumulating. This simple fact, which has

-been attested by the evidence of so many travellers, furnishes us

-with a general solution of the phenomenon, in showing that active

-volcanoes are to be considered as safety-valves for the immediate

-neighbourhood. There are instances in which the earth has been shaken

-for many successive days in the chain of the Andes, in South America.

-In certain districts, the inhabitants take no more notice of the number

-of earthquakes than we in Europe take of showers of rain; yet in such

-a district Bonpland and Humboldt were compelled to dismount, from the

-restiveness of their mules, because the earth shook in a forest for

-fifteen to eighteen minutes _without intermission_.

-

-

-EARTHQUAKES AND THE MOON.

-

-From a careful discussion of several thousand earthquakes which have

-been recorded between 1801 and 1850, and a comparison of the periods at

-which they occurred with the position of the moon in relation to the

-earth, M. Perry, of Dijon, infers that earthquakes may possibly be the

-result of attraction exerted by that body on the supposed fluid centre

-of our globe, somewhat similar to that which she exercises on the

-waters of the ocean; and the Committee of the Institute of France have

-reported favourably upon this theory.

-

-

-THE GREAT EARTHQUAKE OF LISBON.

-

-The eloquent Humboldt remarks, that the activity of an igneous

-mountain, however terrific and picturesque the spectacle may be which

-it presents to our contemplation, is always limited to a very small

-space. It is far otherwise with earthquakes, which, although scarcely

-perceptible to the eye, nevertheless simultaneously propagate their

-waves to a distance of many thousand miles. The great earthquake which

-destroyed the city of Lisbon, November 1st, 1755, was felt in the

-Alps, on the coast of Sweden, into the Antilles, Antigua, Barbadoes,

-and Martinique; in the great Canadian lakes, in Thuringia, in the

-flat country of northern Germany, and in the small inland lakes on

-the shores of the Baltic. Remote springs were interrupted in their

-flow,--a phenomenon attending earthquakes which had been noticed among

-the ancients by Demetrius the Callatian. The hot springs of Töplitz

-dried up and returned, inundating every thing around, and having their

-waters coloured with iron ochre. At Cadiz, the sea rose to an elevation

-of sixty-four feet; while in the Antilles, where the tide usually

-rises only from twenty-six to twenty-eight inches, it suddenly rose

-about twenty feet, the water being of an inky blackness. It has been

-computed that, on November 1st, 1755, a portion of the earth’s surface

-four times greater than that of Europe was simultaneously shaken.[31]

-As yet there is no manifestation of force known to us (says the

-vivid denunciation of the philosopher), including even the murderous

-invention of our own race, by which a greater number of people have

-been killed in the short space of a few minutes: 60,000 were destroyed

-in Sicily in 1693, from 30,000 to 40,000 in the earthquake of Riobamba

-in 1797, and probably five times as many in Asia Minor and Syria under

-Tiberius and Justinian the elder, about the years 19 and 526.

-

-

-GEOLOGICAL AGE OF THE DIAMOND.

-

-The discovery of Diamonds in Russia, far from the tropical zone, has

-excited much interest among geologists. In the detritus on the banks

-of the Adolfskoi, no fewer than forty diamonds have been found in the

-gold alluvium, only twenty feet above the stratum in which the remains

-of mammoths and rhinoceroses are found. Hence Humboldt has concluded

-that the formation of gold-veins, and consequently of diamonds, is

-comparatively of recent date, and scarcely anterior to the destruction

-of the mammoths. Sir Roderick Murchison and M. Verneuil have been led

-to the same result by different arguments.[32]

-

-

-WHAT WAS ADAMANT?

-

-Professor Tennant replies, that the Adamant described by Pliny was a

-sapphire, as proved by its form, and by the fact that when struck on

-an anvil by a hammer it would make an indentation in the metal. A true

-diamond, under such circumstances, would fly into a thousand pieces.

-

-

-WHAT IS COAL?

-

-The whole evidence we possess as to the nature of Coal proves it to

-have been originally a mass of vegetable matter. Its microscopical

-characters point to its having been formed on the spot in which we

-find it, to its being composed of vegetable tissues of various kinds,

-separated and changed by maceration, pressure, and chemical action,

-and to the introduction of its earthy matter, in a large number of

-instances, in a state of solution or fine molecular subdivision. Dr.

-Redfern, from whose communication to the British Association we quote,

-knows nothing to countenance the supposition that our coal-beds are

-mainly formed of coniferous wood, because the structures found in

-mother-coal, or the charcoal layer, have not the character of the

-glandular tissue of such wood, as has been asserted.

-

-Geological research has shown that the immense forests from which our

-coal is formed teemed with life. A frog as large as an ox existed in

-the swamps, and the existence of insects proves that the higher order

-of organic creation flourished at this epoch.

-

-It has been calculated that the available coal-beds in Lancashire

-amount in weight to the enormous sum of 8,400,000,000 tons. The total

-annual consumption of this coal, it has been estimated, amounts to

-3,400,120 tons; hence it is inferred that the coal-beds of Lancashire,

-at the present rate of consumption, will last 2470 years. Making

-similar calculations for the coal-fields of South Wales, the north of

-England, and Scotland, it will readily be perceived how ridiculous were

-the forebodings which lecturing geologists delighted to indulge in a

-few years ago.

-

-

-TORBANE-HILL COAL.

-

-The coal of Torbane Hill, Scotland, is so highly inflammable, that it

-has been disputed at law whether it be true coal, or only asphaltum,

-or bitumen. Dr. Redfern describes it as laminated, splitting with

-great ease horizontally, like many cannel coals, and like them it may

-be lighted at a candle. In all parts of the bed stigmaria and other

-fossil plants occur in greater numbers than in most other coals; their

-distinct vascular tissue may be easily recognised by a common pocket

-lens, and 65½ of the mass consists of carbon.

-

-Dr. Redfern considers that all our coals may be arranged in a scale

-having the Torbane-Hill coal at the top and anthracite at the bottom.

-Anthracite is almost pure carbon; Torbane Hill contains less fixed

-carbon than most other cannels: anthracite is very difficult to ignite,

-and gives out scarcely any gas; Torbane-Hill burns like a candle, and

-yields 3000 cubic feet of gas per ton, more than any other known coal,

-its gas being also of greatly superior illuminating power to any other.

-The only differences which the Torbane-Hill coal presents from others

-are differences of degree, not of kind. It differs from other coals

-in being the best gas-coal, and from other cannels in being the best

-cannel.

-

-

-HOW MALACHITE IS FORMED.

-

-The rich copper-ore of the Ural, which occurs in veins or masses,

-amid metamorphic strata associated with igneous rocks, and even in

-the hollows between the eruptive rocks, is worked in shafts. At the

-bottom of one of these, 280 feet deep, has been found an enormous

-irregularly-shaped botryoidal mass of _Malachite_ (Greek _malache_,

-mountain-green), sending off strings of green copper-ore. The upper

-surface of it is about 18 feet long and 9 wide; and it was estimated

-to contain 15,000 poods, or half a million pounds, of pure and compact

-malachite. Sir Roderick Murchison is of opinion that this wonderful

-subterraneous incrustation has been produced in the stalagmitic form,

-during a series of ages, by copper solutions emanating from the

-surrounding loose and sporous mass, and trickling through it to the

-lowest cavity upon the subjacent solid rock. Malachite is brought

-chiefly from one mine in Siberia; its value as raw material is nearly

-one-fourth that of the same weight of pure silver, or in a manufactured

-state three guineas per pound avoirdupois.[33]

-

-

-LUMPS OF GOLD IN SIBERIA.

-

-The gold mines south of Miask are chiefly remarkable for the large

-lumps or _pepites_ of gold which are found around the Zavod of

-Zarevo-Alexandroisk. Previous to 1841 were discovered here lumps of

-native gold; in that year a lump of twenty-four pounds was met with;

-and in 1843 a lump weighing about seventy-eight pounds English was

-found, and is now deposited with others in the Museum of the Imperial

-School of Mines at St. Petersburg.

-

-

-SIR ISAAC NEWTON UPON BURNET’S THEORY OF THE EARTH.

-

-In 1668, Dr. Thomas Burnet printed his _Theoria Telluris Sacra_,

-“an eloquent physico-theological romance,” says Sir David Brewster,

-“which was to a certain extent adopted even by Newton, Burnet’s

-friend. Abandoning, as some of the fathers had done, the hexaëmeron,

-or six days of Moses, as a physical reality, and having no knowledge

-of geological phenomena, he gives loose reins to his imagination,

-combining passages of Scripture with those of ancient authors, and

-presumptuously describing the future catastrophes to which the earth is

-to be exposed.” Previous to its publication, Burnet presented a copy

-of his book to Newton, and requested his opinion of the theory which

-it propounded. Newton took “exceptions to particular passages,” and

-a correspondence ensued. In one of Newton’s letters he treats of the

-formation of the earth, and the other planets, out of a general chaos

-of the figure assumed by the earth,--of the length of the primitive

-days,--of the formation of hills and seas, and of the creation of the

-two ruling lights as the result of the clearing up of the atmosphere.

-He considers the account of the creation in Genesis as adapted to the

-judgment of the vulgar. “Had Moses,” he says, “described the processes

-of creation as distinctly as they were in themselves, he would have

-made the narrative tedious and confused amongst the vulgar, and become

-a philosopher more than a prophet.” After referring to several “causes

-of meteors, such as the breaking out of vapours from below, before

-the earth was well hardened, the settling and shrinking of the whole

-globe after the upper regions or surface began to be hard,” Newton

-closes his letter with an apology for being tedious, which, he says,

-“he has the more reason to do, as he has not set down any thing he has

-well considered, or will undertake to defend.”--See the Letter in the

-Appendix to _Sir D. Brewster’s Life of Newton_, vol. ii.

-

-  The primitive condition of the earth, and its preparation for

-  man, was a subject of general speculation at the close of the

-  seventeenth century. Leibnitz, like his great rival (Newton),

-  attempted to explain the formation of the earth, and of the

-  different substances which composed it; and he had the advantage

-  of possessing some knowledge of geological phenomena: the earth

-  he regarded as having been originally a burning mass, whose

-  temperature gradually diminished till the vapours were condensed

-  into a universal ocean, which covered the highest mountains, and

-  gradually flowed into vacuities and subterranean cavities produced

-  by the consolidation of the earth’s crust. He regarded fossils

-  as the real remains of plants and animals which had been buried

-  in the strata; and, in speculating on the formation of mineral

-  substances, he speaks of crystals as the geometry of inanimate

-  nature.--_Brewster’s Life of Newton_, vol. ii. p. 100, note. (See

-  also “The Age of the Globe,” in _Things not generally Known_, p.

-  13.)

-

-

-“THE FATHER OF ENGLISH GEOLOGY.”

-

-In 1769 was born, the son of a yeoman of Oxfordshire, William

-Smith. When a boy he delighted to wander in the fields, collecting

-“pound-stones” (_Echinites_), “pundibs” (_Terebratulæ_), and other

-stony curiosities; and receiving little education beyond what he taught

-himself, he learned nothing of classics but the name. Grown to be a

-man, he became a land-surveyor and civil engineer, and was much engaged

-in constructing canals. While thus occupied, he observed that all the

-rocky masses forming the substrata of the country were gently inclined

-to the east and south-east,--that the red sandstones and marls above

-the _coal-measures_ passed below the beds provincially termed lias-clay

-and limestone--that these again passed underneath the sands, yellow

-limestone, and clays that form the table-land of the Coteswold Hills;

-while they in turn plunged beneath the great escarpment of chalk that

-runs from the coast of Dorsetshire northward to the Yorkshire shores

-of the German Ocean. He further observed that each formation of clay,

-sand, or limestone, held to a very great extent its own peculiar suite

-of fossils. The “snake-stones” (_Ammonites_) of the lias were different

-in form and ornament from those of the inferior oolite; and the

-shells of the latter, again, differed from those of the Oxford clay,

-Cornbrash, and Kimmeridge clay. Pondering much on these things, he

-came to the then unheard-of conclusion that each formation had been in

-its turn a sea-bottom, in the sediments of which lived and died marine

-animals now extinct, many specially distinctive of their own epochs in

-time.

-

-Here indeed was a discovery,--made, too, by a man utterly unknown to

-the scientific world, and having no pretension to scientific lore.

-“Strata Smith’s” find was unheeded for many a long year; but at length

-the first geologists of the day learned from the land-surveyor that

-superposition of strata is inseparably connected with the succession

-of life in time. Hooke’s grand vision was at length realised, and it

-was indeed possible “to build up a terrestrial chronology from rotten

-shells” imbedded in the rocks. Meanwhile he had constructed the first

-geological map of England, which has served as a basis for geological

-maps of all other parts of the world. William Smith was now presented

-by the Geological Society with the Wollaston Medal, and hailed as “the

-Father of English Geology.” He died in 1840. Till the manner as well

-as the fact of the first appearance of successive forms of life shall

-be solved, it is not easy to surmise how any discovery can be made in

-geology equal in value to that which we owe to the genius of William

-Smith.--_Saturday Review_, No. 140.

-

-

-DR. BUCKLAND’s GEOLOGICAL LABOURS.

-

-Sir Henry De la Beche, in his Anniversary Address to the Geological

-Society in 1848, on presenting the Wollaston Medal to Dr. Buckland,

-felicitously observed:

-

-  It may not be generally known that, while yet a child, at your

-  native town, Axminster in Devonshire, ammonites, obtained by your

-  father from the lime quarries in the neighbourhood, were presented

-  to your attention. As a scholar at Winchester, the chalk, with its

-  flints, was brought under your observation, and there it was that

-  your collections in natural history first began. Removed to Oxford,

-  as a scholar of Corpus Christi College, the future teacher of

-  geology in that University was fortunate in meeting with congenial

-  tastes in our colleague Mr. W. J. Broderip, then a student at Oriel

-  College. It was during your walks together to Shotover Hill, when

-  his knowledge of conchology was so valuable to you, enabling you

-  to distinguish the shells of the Oxford oolite, that you laid the

-  foundation for those field-lectures, forming part of your course

-  of geology at Oxford, which no one is likely to forget who has

-  been so fortunate at any time as to have attended them. The fruits

-  of your walks with Mr. Broderip formed the nucleus of that great

-  collection, more especially remarkable for the organic remains

-  it contains, which, after the labours of forty years, you have

-  presented to the Geological Museum at Oxford, in grave recollection

-  of the aid which the endowments of that University, and the leisure

-  of its vacations, had afforded you for extensive travelling during

-  a residence at Oxford of nearly forty-five years.

-

-

-DISCOVERIES OF M. AGASSIZ.[34]

-

-This great paleontologist, in the course of his ichthyological

-researches, was led to perceive that the arrangement by Cuvier

-according to organs did not fulfil its purpose with regard to fossil

-fishes, because in the lapse of ages the characteristics of their

-structures were destroyed. He therefore adopted the only other

-remaining plan, and studied the tissues, which, being less complex

-than the organs, are oftener found intact. The result was the very

-remarkable discovery, that the tegumentary membrane of fishes is so

-intimately connected with their organisation, that if the whole of the

-fish has perished except this membrane, it is practicable, by noting

-its characteristics, to reconstruct the animal in its most essential

-parts. Of the value of this principle of harmony, some idea may be

-formed from the circumstance, that on it Agassiz has based the whole

-of that celebrated classification of which he is the sole author, and

-by which fossil ichthyology has for the first time assumed a precise

-and definite shape. How essential its study is to the geologist appears

-from the remark of Sir Roderick Murchison, that “fossil fishes have

-every where proved the most exact chronometer of the age of rocks.”

-

-

-SUCCESSION OF LIFE IN TIME.

-

-In the Museum of Economic Geology, in Jermyn Street, may be seen ores,

-metals, rocks, and whole suites of fossils stratigraphically arranged

-in such a manner that, with an observant eye for form, all may easily

-understand the more obvious scientific meanings of the Succession

-of Life in Time, and its bearing on geological economies. It is

-perhaps scarcely an exaggeration to say, that the greater number of

-so-called educated persons are still ignorant of the meaning of this

-great doctrine. They would be ashamed not to know that there are many

-suns and material worlds besides our own; but the science, equally

-grand and comprehensible, that aims at the discovery of the laws that

-regulated the creation, extension, decadence, and utter extinction of

-many successive species, genera, and whole orders of life, is ignored,

-or, if intruded on the attention, is looked on as an uncertain and

-dangerous dream,--and this in a country which was almost the nursery of

-geology, and which for half a century has boasted the first Geological

-Society in the world.--_Saturday Review_, No. 140.

-

-

-PRIMITIVE DIVERSITY AND NUMBERS OF ANIMALS IN GEOLOGICAL TIMES.

-

-Professor Agassiz considers that the very fact of certain stratified

-rocks, even among the oldest formations, being almost entirely made

-up of fragments of organised beings, should long ago have satisfied

-the most sceptical that both _animal and vegetable life were as active

-and profusely scattered upon the whole globe at all times, and during

-all geological periods, as they are now_. No coral reef in the Pacific

-contains a larger amount of organic _débris_ than some of the limestone

-deposits of the tertiary, of the cretaceous, or of the oolitic, nay

-even of the paleozoic period; and the whole vegetable carpet covering

-the present surface of the globe, even if we were to consider only

-the luxuriant vegetation of the tropics, leaving entirely out of

-consideration the entire expanse of the ocean, as well as those tracts

-of land where, under less favourable circumstances, the growth of

-plants is more reduced,--would not form one single seam of workable

-coal to be compared to the many thick beds contained in the rocks of

-the carboniferous period alone.

-

-

-ENGLAND IN THE EOCENE PERIOD.

-

-Eocene is Sir Charles Lyell’s term for the lowest group of the Tertiary

-system in which the dawn of recent life appears; and any one who wishes

-to realise what was the aspect presented by this country during the

-Eocene period, need only go to Sheerness. If, leaving that place behind

-him, he walks down the Thames, keeping close to the edge of the water,

-he will find whole bushels of pyritised pieces of twigs and fruits.

-These fruits and twigs belong to plants nearly allied to the screw-pine

-and custard-apple, and to various species of palms and spice-trees

-which now flourish in the Eastern Archipelago. At the time they were

-washed down from some neighbouring land, not only crocodilian reptiles,

-but sharks and innumerable turtles, inhabited a sea or estuary which

-now forms part of the London district; and huge boa-constrictors glided

-amongst the trees which fringed the adjoining shores.

-

-Countless as are the ages which intervened between the Eocene period

-and the time when the little jawbones of Stonesfield were washed down

-to the place where they were to await the day when science should bring

-them again to light, not one mammalian genus which now lives upon our

-plane has been discovered amongst Eocene strata. We have existing

-families, but nothing more.--_Professor Owen._

-

-

-FOOD OF THE IGUANODON.

-

-Dr. Mantell, from the examination of the anterior part of the right

-side of the lower jaw of an Iguanodon discovered in a quarry in Tilgate

-Forest, Sussex, has detected an extraordinary deviation from all

-known types of reptilian organisation, and which could not have been

-predicated; namely, that this colossal reptile, which equalled in bulk

-the gigantic Edentata of South America, and like them was destined to

-obtain support from comminuted vegetable substances, was also furnished

-with a large prehensile tongue and fleshy lips, to serve as instruments

-for seizing and cropping the foliage and branches of trees; while

-the arrangement of the teeth as in the ruminants, and their internal

-structure, which resembles that of the molars of the sloth tribe in the

-vascularity of the dentine, indicate adaptations for the same purpose.

-

-Among the physiological phenomena revealed by paleontology, there

-is not a more remarkable one than this modification of the type of

-organisation peculiar to the class of reptiles to meet the conditions

-required by the economy of a lizard placed under similar physical

-relations; and destined to effect the same general purpose in the

-scheme of nature as the colossal Edentata of former ages and the large

-herbivorous mammalia of our own times.

-

-

-THE PTERODACTYL--THE FLYING DRAGON.

-

-The Tilgate beds of the Wealden series, just mentioned, have yielded

-numerous fragments of the most remarkable reptilian fossils yet

-discovered, and whose wonderful forms denote them to have thronged

-the shallow seas and bays and lagoons of the period. In the grounds

-of the Crystal Palace at Sydenham the reader will find restorations

-of these animals sufficiently perfect to illustrate this reptilian

-epoch. They include the _iguanodon_, an herbivorous lizard exceeding

-in size the largest elephant, and accompanied by the equally gigantic

-and carnivorous _megalosaurus_ (great saurian), and by the two yet more

-curious reptiles, the _pylæosaurus_ (forest, or weald, saurian) and the

-pterodactyl (from _pteron_, ‘wing,’ and _dactylus_, ‘a finger’), an

-enormous bat-like creature, now running upon the ground like a bird;

-its elevated body and long neck not covered with feathers, but with

-skin, naked, or resplendent with glittering scales; its head like that

-of a lizard or crocodile, and of a size almost preposterous compared

-with that of the body, with its long fore extremities stretched out,

-and connected by a membrane with the body and hind legs.

-

-Suddenly this mailed creature rose in the air, and realised or even

-surpassed in strangeness _the flying dragon of fable_: its fore-arms

-and its elongated wing-finger furnished with claws; hand and fingers

-extended, and the interspace filled up by a tough membrane; and its

-head and neck stretched out like that of the heron in its flight. When

-stationary, its wings were probably folded back like those of a bird;

-though perhaps, by the claws attached to its fingers, it might suspend

-itself from the branches of trees.

-

-

-MAMMALIA IN SECONDARY ROCKS.

-

-It was supposed till very lately that few if any Mammalia were to be

-found below the Tertiary rocks, _i. e._ those above the chalk; and this

-supposed fact was very comfortable to those who support the doctrine

-of “progressive development,” and hold, with the notorious _Vestiges

-of Creation_, that a fish by mere length of time became a reptile,

-a lemur an ape, and finally an ape a man. But here, as in a hundred

-other cases, facts, when duly investigated, are against their theory.

-A mammal jaw had been already discovered by Mr. Brodie on the shore at

-the back of Swanage Point, in Dorsetshire, when Mr. Beckles, F.G.S.,

-traced the vein from which this jaw had been procured, and found it

-to be a stratum about five inches thick, at the base of the Middle

-Purbeck beds; and after removing many thousand tons of rock, and laying

-bare an area of nearly 7000 square feet (the largest cutting ever made

-for purely scientific purposes), he found reptiles (tortoises and

-lizards) in hundreds; but the most important discovery was that of

-the jaws of at least fourteen different species of mammalia. Some of

-these were herbivorous, some carnivorous, connected with our modern

-shrews, moles, hedgehogs, &c.; but all of them perfectly developed and

-highly-organised quadrupeds. Ten years ago, no remains of quadrupeds

-were believed to exist in the Secondary strata. “Even in 1854,” says

-Sir Charles Lyell (in a supplement to the fifth edition of his _Manual

-of Elementary Geology_), “only six species of mammals from rocks older

-than the Tertiary were known in the whole world.” We now possess

-evidence of the existence of fourteen species, belonging to eight or

-nine genera, from the fresh-water strata of the Middle Purbeck Oolite.

-It would be rash now to fix a limit in past time to the existence of

-quadrupeds.--_The Rev. C. Kingsley._

-

-

-FOSSIL HUMAN BONES.

-

-In the paleontological collection in the British Museum is preserved

-a considerable portion of a human skeleton imbedded in a slab of

-rock, brought from Guadaloupe, and often referred to in opposition to

-the statement that hitherto _no fossil human hones have been found_.

-The presence of these bones, however, has been explained by the

-circumstance of a battle and the massacre of a tribe of Galtibis by the

-Caribs, which took place near the spot in which the bones were found

-about 130 years ago; for as the bodies of the slain were interred on

-the seashore, their skeletons may have been subsequently covered by

-sand-drift, which has since consolidated into limestone.

-

-It will be seen by reference to the _Philosophical Transactions_,

-that on the reading of the paper upon this discovery to the Royal

-Society, in 1814, Sir Joseph Banks, the president, considered the

-“fossil” to be of very modern formation, and that probably, from the

-contiguity of a volcano, the temperature of the water may have been

-raised at some time, and dissolving carbonate of lime readily, may

-have deposited about the skeleton in a comparatively short period hard

-and solid stone. Every person may be convinced of the rapidity of the

-formation and of the hardness of such stone by inspecting the inside of

-tea-kettles in which hard water is boiled.

-

-  Descriptions of petrifactions of human bodies appear to refer to

-  the conversion of bodies into adipocere, and not into stone. All

-  the supposed cases of petrifaction are probably of this nature.

-  The change occurs only when the coffin becomes filled with water.

-  The body, converted into adipocere, floats on the water. The

-  supposed cases of changes of position in the grave, bursting open

-  the coffin-lids, turning over, crossing of limbs, &c., formerly

-  attributed to the coming to life of persons buried who were not

-  dead, is now ascertained to be due to the same cause. The chemical

-  change into adipocere, and the evolution of gases, produce these

-  movements of dead bodies.--_Mr. Trail Green._

-

-

-THE MOST ANCIENT FISHES.

-

-Among the important results of Sir Roderick Murchison’s establishment

-of the Silurian system is the following:

-

-  That as the Lower Silurian group, often of vast dimensions, has

-  never afforded the smallest vestige of a Fish, though it abounds

-  in numerous species of the _marine_ classes,--corals, _crinoidea_,

-  _mollusca_, and _crustacea_; and as in Scandinavia and Russia,

-  where it is based on rocks void of fossils, its lowest stratum

-  contains _fucoids_ only,--Sir R. Murchison has, after fifteen years

-  of laborious research steadily directed to this point, arrived at

-  the conclusion, that a very long period elapsed after life was

-  breathed into the waters before the lowest order of vertebrata was

-  created; the earliest fishes being those of the Upper Silurian

-  rocks, which he was the first to discover, and which he described

-  “as the most ancient beings of their class which have yet been

-  brought to light.” Though the Lower Silurian rocks of various parts

-  of the world have since been ransacked by multitudes of prying

-  geologists, who have exhumed from them myriads of marine fossils,

-  not a single ichthyolite has been found in any stratum of higher

-  antiquity than the Upper Silurian group of Murchison.

-

-The most remarkable of all fossil fishes yet discovered have been found

-in the Old Red Sandstone cliffs at Dorpat, where the remains are so

-gigantic (one bone measuring _two feet nine inches_ in length) that

-they were at first supposed to belong to saurians.

-

-Sir Roderick’s examination of Russia has, in short, proved that _the

-ichthyolites and mollusks which, in Western Europe, are separately

-peculiar to smaller detached basins, were here (in the British Isles)

-cohabitants of many parts of the same great sea_.

-

-

-EXTINCT CARNIVOROUS ANIMALS OF BRITAIN.

-

-Professor Owen has thus forcibly illustrated the Carnivorous Animals

-which preyed upon and restrained the undue multiplication of the

-vegetable feeders. First we have the bear family, which is now

-represented in this country only by the badger. We were once blest,

-however, with many bears. One species seems to have been identical

-with the existing brown bear of the European continent. Far larger

-and more formidable was the gigantic cave-bear (_Ursus spelæus_),

-which surpassed in size his grisly brother of North America. The

-skull of the cave-bear differs very much in shape from that of its

-small brown relative just alluded to; the forehead, in particular,

-is much higher,--to be accounted for by an arrangement of air-cells

-similar to those which we have already remarked in the elephant. The

-cave-bear has left its remains in vast abundance in Germany. In our own

-caves, the bones of hyænas are found in greater quantities. The marks

-which the teeth of the hyæna make upon the bones which it gnaws are

-quite unmistakable. Our English hyænas had the most undiscriminating

-appetite, preying upon every creature, their own species amongst

-others. Wolves, not distinguishable from those which now exist in

-France and Germany, seem to have kept company with the hyænas; and the

-_Felis spelæa_, a sort of lion, but larger than any which now exists,

-ruled over all weaker brutes. Here, says Professor Owen, we have the

-original British Lion. A species of _Machairodus_ has left its remains

-at Kent’s Hole, near Torquay. In England we had also the beaver, which

-still lingers on the Danube and the Rhone, and a larger species, which

-has been called Trogontherium (gnawing beast), and a gigantic mole.

-

-

-THE GREAT CAVE TIGER OR LION OF BRITAIN.

-

-Remains of this remarkable animal of the drift or gravel period

-of this country have been found at Brentford and elsewhere near

-London. Speaking of this animal, Professor Owen observes, that “it

-is commonly supposed that the Lion, the Tiger, and the Jaguar are

-animals peculiarly adapted to a tropical climate. The genus Felis (to

-which these animals belong) is, however, represented by specimens

-in high northern latitudes, and in all the intermediate countries

-to the equator.” The chief condition necessary for the presence of

-such animals is an abundance of the vegetable-feeding animals. It

-is thus that the Indian tiger has been known to follow the herds of

-antelope and deer in the lofty mountains of the Himalaya to the verge

-of perpetual snow, and far into Siberia. “It need not, therefore,”

-continues Professor Owen, “excite surprise that indications should

-have been discovered in the fossil relics of the ancient mammalian

-population of Europe of a large feline animal, the contemporary of the

-mammoth, of the tichorrhine rhinoceros, of the great gigantic cave-bear

-and hyæna, and the slayer of the oxen, deer, and equine quadrupeds that

-so abounded during the same epoch.” The dimensions of this extinct

-animal equal those of the largest African lion or Bengal tiger; and

-some bones have been found which seem to imply that it had even more

-powerful limbs and larger paws.

-

-

-THE MAMMOTHS OF THE BRITISH ISLES.

-

-Dr. Buckland has shown that for long ages many species of carnivorous

-animals now extinct inhabited the caves of the British islands. In low

-tracts of Yorkshire, where tranquil lacustrine (lake-like) deposits

-have occurred, bones (even those of the lion) have been found so

-perfectly unbroken and unworn, in fine gravel (as at Market Weighton),

-that few persons would be disposed to deny that such feline and other

-animals once roamed over the British isles, as well as other European

-countries. Why, then, is it improbable that large elephants, with a

-peculiarly thick integument, a close coating of wool, and much long

-shaggy hair, should have been the occupants of wide tracts of Northern

-Europe and Asia? This coating, Dr. Fleming has well remarked, was

-probably as impenetrable to rain and cold as that of the monster ox of

-the polar circle. Such is the opinion of Sir Roderick Murchison, who

-thus accounts for the disappearance of the mammoths from Britain:

-

-  When we turn from the great Siberian continent, which, anterior

-  to its elevation, was the chief abode of the mammoths, and look

-  to the other parts of Europe, where their remains also occur, how

-  remarkable is it that we find the number of these creatures to be

-  justly proportionate to the magnitude of the ancient masses of land

-  which the labours of geologists have defined! Take the British

-  isles, for example, and let all their low, recently elevated

-  districts be submerged; let, in short, England be viewed as the

-  comparatively small island she was when the ancient estuary of the

-  Thames, including the plains of Hyde Park, Chelsea, Hounslow, and

-  Uxbridge, were under the water; when the Severn extended far into

-  the heart of the kingdom, and large eastern tracts of the island

-  were submerged,--and there will then remain but moderately-sized

-  feeding-grounds for the great quadrupeds whose bones are found in

-  the gravel of the adjacent rivers and estuaries.

-

-This limited area of subsistence could necessarily only keep up a small

-stock of such animals; and, just as we might expect, the remains of

-British mammoths occur in very small numbers indeed, when compared with

-those of the great charnel-houses of Siberia, into which their bones

-had been carried down through countless ages from the largest mass of

-surface which geological inquiries have yet shown to have been _dry

-land_ during that epoch.

-

-The remains of the mammoth, says Professor Owen, have been found in

-all, or almost all, the counties of England. Off the coast of Norfolk

-they are met with in vast abundance. The fishermen who go to catch

-turbot between the mouth of the Thames and the Dutch coast constantly

-get their nets entangled in the tusks of the mammoth. A collection

-of tusks and other remains, obtained in this way, is to be seen at

-Ramsgate. In North America, this gigantic extinct elephant must have

-been very common; and a large portion of the ivory which supplies

-the markets of Europe is derived from the vast mammoth graveyards of

-Siberia.

-

-The mammoth ranged at least as far north as 60°. There is no doubt

-that, at the present day, many specimens of the musk-ox are annually

-becoming imbedded in the mud and ice of the North-American rivers.

-

-It is curious to observe, that the mammoth teeth which are met with

-in caves generally belonged to young mammoths, who probably resorted

-thither for shelter before increasing age and strength emboldened them

-to wander far afield.

-

-

-THE RHINOCEROS AND HIPPOPOTAMUS OF ENGLAND.

-

-The mammoth was not the only giant that inhabited England in the

-Pliocene or Upper Tertiary period. We had also here the _Rhinoceros

-tichorrhinus_, or “strongly walled about the nose,” remains of which

-have been discovered in enormous quantities in the brickfields about

-London. Pallas describes an entire specimen of this creature, which was

-found near Yakutsk, the coldest town on the globe. Another rhinoceros,

-_leptorrhinus_ (fine nose), dwelt with the elephant of Southern Europe.

-In Siberia has been discovered the Elaimotherium, forming a link

-between the rhinoceros and the horse.

-

-In the days of the mammoth, we had also in England a Hippopotamus,

-rather larger than the species which now inhabits the Nile. Of our

-British hippopotamus some remains were dug up by the workmen in

-preparing the foundations of the New Junior United Service Club-house,

-in Regent-street.

-

-

-THE ELEPHANT AND TORTOISE.

-

-The idea of an Elephant standing on the back of a Tortoise was often

-laughed at as an absurdity, until Captain Cautley and Dr. Falconer

-at length discovered in the hills of Asia the remains of a tortoise

-in a fossil state of such a size that an elephant could easily have

-performed the above feat.

-

-

-COEXISTENCE OF MAN AND THE MASTODON.

-

-Dr. C. F. Winslow has communicated to the Boston Society of Natural

-History the discovery of the fragment of a human cranium 180 feet below

-the surface of the Table Mountain, California. Now the mastodon’s

-bones being found in the same deposits, points very clearly to the

-probability of the appearance of the human race on the western

-portions of North America at least before the extinction of those huge

-creatures. Fragments of mastodon and _Elephas primigenius_ have been

-taken ten and twenty feet below the surface in the above locality;

-where this discovery of human and mastodon remains gives strength

-to the possible truth of an old Indian tradition,--the contemporary

-existence of the mammoth and aboriginals in this region of the globe.

-

-

-HABITS OF THE MEGATHERIUM.

-

-Much uncertainty has been felt about the habits of the Megatherium,

-or Great Beast. It has been asked whether it burrowed or climbed, or

-what it did; and difficulties have presented themselves on all sides of

-the question. Some have thought that it lived in trees as much larger

-than those which now exist as the Megatherium itself is larger than

-the common sloth.[35] This, however, is now known to be a mistake.

-It did not climb trees--it pulled them down; and in order to do this

-the hinder parts of its skeleton were made enormously strong, and

-its prehensile fore-legs formed so as to give it a tremendous power

-over any thing which it grasped. Dr. Buckland suggested that animals

-which got their living in this way had a very fair chance of having

-their heads broken. While Professor Owen was still pondering over this

-difficulty, the skull of a cognate animal, the Mylodon, came into

-his hands. Great was his delight when he found that the mylodon not

-only had his head broken, but broken in two different places, at two

-different times; and moreover so broken that the injury could only have

-been inflicted by some such agent as a fallen tree. The creature had

-recovered from the first blow, but had evidently died of the second.

-This tribe had, as it turns out, two skulls, an outer and an inner

-one--given them, as it would appear, expressly with a view to the very

-dangerous method in which they were intended to obtain their necessary

-food.

-

-The dentition of the megatherium is curious. The elephant gets teeth

-as he wants them. Nature provided for the comfort of the megatherium

-in another way. It did not get new teeth, but the old ones went on

-for ever growing as long as the animal lived; so that as fast as one

-grinding surface became useless, another supplied its place.

-

-

-THE DINOTHERIUM, OR TERRIBLE BEAST.

-

-The family of herbivorous Cetaceans are connected with the

-Pachydermata of the land by one of the most wonderful of all the

-extinct creatures with which geologists have made us acquainted.

-This is the _Dinotherium_, or Terrible Beast. The remains of this

-animal were found in Miocene sands at Eppelsheim, about forty miles

-from Darmstadt. It must have been larger than the largest extinct or

-living elephant. The most remarkable peculiarity of its structure is

-the enormous tusks, curving downwards and terminating its lower jaw.

-It appears to have lived in the water, where the immense weight of

-these formidable appendages would not be so inconvenient as on land.

-What these tusks were used for is a mystery; but perhaps they acted

-as pickaxes in digging up trees and shrubs, or as harrows in raking

-the bottom of the water. Dr. Buckland used to suggest that they were

-perhaps employed as anchors, by means of which the monster might

-fasten itself to the bank of a stream and enjoy a comfortable nap. The

-extreme length of the _Dinotherium_ was about eighteen feet. Professor

-Kemp, in his restoration of the animal, has given it a trunk like

-that of the elephant, but not so long, and the general form of the

-tapir.--_Professor Owen._

-

-

-THE GLYPTODON.

-

-There are few creatures which we should less have expected to find

-represented in fossil history by a race of gigantic brethren than the

-armadillo. The creature is so small, not only in size but in all its

-works and ways, that we with difficulty associate it with the idea of

-magnitude. Yet Sir Woodbine Parish has discovered evidences of enormous

-animals of this family having once dwelt in South America. The huge

-loricated (plated over) creature whose relics were first sent has

-received the name of Glyptodon, from its sculptured teeth. Unlike the

-small armadillos, it was unable to roll itself up into a ball; though

-an enormous carnivore which lived in those days must have made it

-sometimes wish it had the power to do so. When attacked, it must have

-crouched down, and endeavoured to make its huge shell as good a defence

-as possible.--_Professor Owen._

-

-

-INMATES OF AN AUSTRALIAN CAVERN.

-

-From the fossil-bone caverns in Wellington Valley, in 1830, were sent

-to Professor Owen several bones which belonged, as it turned out, to

-gigantic kangaroos, immensely larger than any existing species; to

-a kind of wombat, to formidable dasyures, and several other genera.

-It also appeared that the bones, which were those of herbivores, had

-evidently belonged to young animals, while those of the carnivores

-were full-sized; a fact which points to the relations between the two

-families having been any thing but agreeable to the herbivores.

-

-

-THE POUCH-LION OF AUSTRALIA.

-

-The _Thylacoleo_ (Pouch-Lion) was a gigantic marsupial carnivore, whose

-character and affinities Professor Owen has, with exquisite scientific

-tact, made out from very small indications. This monster, which had

-kangaroos with heads three feet long to feed on, must have been one of

-the most extraordinary animals of the antique world.

-

-

-THE CONEY OF SCRIPTURE.

-

-Paleontologists have pointed out the curious fact that the Hyrax,

-called ‘coney’ in our authorised version of the Bible, is really only

-a diminutive and hornless rhinoceros. Remains have been found at

-Eppelsheim which indicate an animal more like a gigantic Hyrax than

-any of the existing rhinoceroses. To this the name of _Acerotherium_

-(Hornless Beast) has been given.

-

-

-A THREE-HOOFED HORSE.

-

-Professor Owen describes the _Hipparion_, or Three-hoofed Horse, as the

-first representative of a family so useful to mankind. This animal,

-in addition to its true hoof, appears to have had two additional

-elementary hoofs, analogous to those which we see in the ox. The object

-of these no doubt was to enable the Hipparion to extricate his foot

-with greater ease than he otherwise could when it sank through the

-swampy ground on which he lived.

-

-

-TWO MONSTER CARNIVORES OF FRANCE.

-

-A huge carnivorous creature has been found in Miocene strata in

-France, in which country it preyed upon the gazelle and antelope. It

-must have been as large as a grisly bear, but in general appearance

-and teeth more like a gigantic dog. Hence the name of _Amphicyon_

-(Doubtful Dog) has been assigned to it. This animal must have derived

-part of its support from vegetables. Not so the coeval monster which

-has been called _Machairodus_ (Sabre-tooth). It must have been

-somewhat akin to the tiger, and is by far the most formidable animal

-which we have met with in our ascending progress through the extinct

-mammalia.--_Professor Owen._

-

-

-GEOLOGY OF THE SHEEP.

-

-No unequivocal fossil remains of the sheep have yet been found in

-the bone-caves, the drift, or the more tranquil stratified newer

-Pliocene deposits, so associated with the fossil bones of oxen,

-wild-boars, wolves, foxes, otters, &c., as to indicate the coevality

-of the sheep with those species, or in such an altered state as to

-indicate them to have been of equal antiquity. Professor Owen had his

-attention particularly directed to this point in collecting evidence

-for a history of British Fossil Mammalia. No fossil core-horns of the

-sheep have yet been any where discovered; and so far as this negative

-evidence goes, we may infer that the sheep is not geologically more

-ancient than man; that it is not a native of Europe, but has been

-introduced by the tribes who carried hither the germs of civilisation

-in their migrations westward from Asia.

-

-

-THE TRILOBITE.

-

-Among the earliest races we have those remarkable forms, the

-Trilobites, inhabiting the ancient ocean. These crustacea remotely

-resemble the common wood-louse, and like that animal they had the power

-of rolling themselves into a ball when attacked by an enemy. The eye of

-the trilobite is a most remarkable organ; and in that of one species,

-_Phacops caudatus_, not less than 250 lenses have been discovered. This

-remarkable optical instrument indicates that these creatures lived

-under similar conditions to those which surround the crustacea of the

-present day.--_Hunt’s Poetry of Science._

-

-

-PROFITABLE SCIENCE.

-

-In that strip of reddish colour which runs along the cliffs of Suffolk,

-and is called the Redcrag, immense quantities of cetacean remains have

-been found. Four different kinds of whales, little inferior in size to

-the whalebone whale, have left their bones in this vast charnel-house.

-In 1840, a singularly perplexing fossil was brought to Professor Owen

-from this Redcrag. No one could say what it was. He determined it to

-be the tooth of a cetacean, a unique specimen. Now the remains of

-cetaceans in the Suffolk crag have been discovered in such enormous

-quantities, that many thousands a-year are made by converting them into

-manure.

-

-

-EXTINCT GIGANTIC BIRDS OF NEW ZEALAND.

-

-In the islands of New Zealand have been found the bones of large

-extinct wingless Birds, belonging to the Post Tertiary or Recent

-system, which have been deposited by the action of rivers. The bird

-is named _Moa_ by the natives, and _Dinornis_ by naturalists: some

-of the bones have been found in two caves in the North Island, and

-have been sold by the natives at an extraordinary price. The caves

-occur in limestone rocks, and the bones are found beneath earth and

-a soft deposit of carbonate of lime. The largest of the birds is

-stated to have stood thirteen or fourteen feet, or twice the height

-of the ostrich; and its egg large enough to fill the hat of a man as

-a cup. Several statements have appeared of these birds being still

-in existence, but there is every reason to believe the Moa to be

-altogether extinct.

-

-An extensive collection of remains of these great wingless birds has

-been collected in New Zealand by Mr. Walter Mantell, and deposited in

-the British Museum. Among these bones Professor Owen has discovered a

-species which he regards as the most remarkable of the feathered class

-for its prodigious strength and massive proportions, and which he names

-_Dinornis elephantopus_, or elephant-footed, of which the Professor

-has been able to construct an entire lower limb: the length of the

-metatarsal bone is 9¼ inches, the breadth of the lower end being

-5-1/3 inches. The extraordinary proportions of the metatarsus of this

-wingless bird will, however, be still better understood by comparison

-with the same bone in the ostrich, in which the metatarsus is 19 inches

-in length, the breadth of its lower end being only 2½ inches. From

-the materials accumulated by Mr. Mantell, the entire skeleton of the

-_Dinornis elephantopus_ has been reconstructed; and now forms a worthy

-companion of the Megatherium and Mastodon in the gallery of fossil

-remains in the British Museum. This species of _Dinornis_ appears to

-have been restricted to the Middle Island of New Zealand.[36]

-

-Another specimen of the remains of the _Dinornis_ is preserved in the

-Museum of the Royal College of Surgeons, in Lincoln’s-Inn Fields; and

-the means by which the college obtained this valuable acquisition is

-thus graphically narrated by Mr. Samuel Warren, F.R.S.:

-

-  In the year 1839, Professor Owen was sitting alone in his study,

-  when a shabbily-dressed man made his appearance, announcing that he

-  had got a great curiosity, which he had brought from New Zealand,

-  and wished to dispose of to him. It had the appearance of an old

-  marrow-bone, about six inches in length, and rather more than

-  two inches in thickness, _with both extremities broken off_; and

-  Professor Owen considered that, to whatever animal it might have

-  belonged, the fragment must have lain in the earth for centuries.

-  At first he considered this same marrow-bone to have belonged to

-  an ox, at all events to a quadruped; for the wall or rim of the

-  bone was six times as thick as the bone of any bird, even of the

-  ostrich. He compared it with the bones in the skeleton of an ox, a

-  horse, a camel, a tapir, and every quadruped apparently possessing

-  a bone of that size and configuration; but it corresponded with

-  none. On this he very narrowly examined the surface of the bony

-  rim, and at length became satisfied that this fragment must have

-  belonged to _a bird_!--to one at least as large as an ostrich, but

-  of a totally different species; and consequently one never before

-  heard of, as an ostrich was by far the biggest bird known.

-

-  From the difference in the _strength_ of the bone, the ostrich

-  being unable to fly, so must have been unable this unknown bird;

-  and so our anatomist came to the conclusion that this old shapeless

-  bone indicated the former existence in New Zealand of some huge

-  bird, at least as great as an ostrich, but of a far heavier and

-  more sluggish kind. Professor Owen was confident of the validity

-  of his conclusions, but would communicate that confidence to

-  no one else; and notwithstanding attempts to dissuade him from

-  committing his views to the public, he printed his deductions

-  in the _Transactions of the Zoological Society for 1839_, where

-  fortunately they remain on record as conclusive evidence of the

-  fact of his having then made this guess, so to speak, in the dark.

-  He caused the bone, however, to be engraved; and having sent a

-  hundred copies of the engraving to New Zealand, in the hope of

-  their being distributed and leading to interesting results, he

-  patiently waited for three years,--viz. till the year 1842,--when

-  he received intelligence from Dr. Buckland, at Oxford, that a

-  great box, just arrived from New Zealand, consigned to himself,

-  was on its way, unopened, to Professor Owen, who found it filled

-  with bones, palpably of a bird, one of which bones was three feet

-  in length, and much more than double the size of any bone in the

-  ostrich!

-

-  And out of the contents of this box the Professor was positively

-  enabled to articulate almost the entire skeleton of a huge wingless

-  bird between TEN and ELEVEN feet in height, its bony structure in

-  strict conformity with the fragment in question; and that skeleton

-  may at any time be seen at the Museum of the College of Surgeons,

-  towering over, and nearly twice the height of, the skeleton of

-  an ostrich; and at its feet lying the old bone from which alone

-  consummate anatomical science had deduced such an astounding

-  reality,--the existence of an enormous extinct creature of the bird

-  kind, in an island where previously no bird had been known to exist

-  larger than a pheasant or a common fowl!--_Lecture on the Moral and

-  Intellectual Development of the present Age._[37]

-

-

-“THE MAESTRICHT SAURIAN FOSSIL” A FRAUD.

-

-In 1795, there was stated to have been discovered in the stone quarries

-adjoining Maestricht the remains of the gigantic _Mosœsaurus_ (Saurian

-of the Meuse), an aquatic reptile about twenty-five feet long, holding

-an intermediate place between the Monitors and Iguanas. It appears

-to have had webbed feet, and a tail of such construction as to have

-served for a powerful oar, and enabled the animal to stem the waves of

-the ocean, of which Cuvier supposed it to have been an inhabitant. It

-is thus referred to by Dr. Mantell, in his _Medals of Creation_: “A

-specimen, with the jaws and bones of the palate, now in the Museum at

-Paris, has long been celebrated; and is still the most precious relic

-of this extinct reptile hitherto discovered.” An admirable cast of this

-specimen is preserved in the British Museum, in a case near the bones

-of the Iguanodon. This is, however, useless, as Cuvier is proved to

-have been imposed upon in the matter.

-

-  M. Schlegel has reported to the French Academy of Sciences, that

-  he has ascertained beyond all doubt that the famous fossil saurian

-  of the quarries of Maestricht, described as a wonderful curiosity

-  by Cuvier, is nothing more than an impudent fraud. Some bold

-  impostor, it seems, in order to make money, placed a quantity of

-  bones in the quarries in such a way as to give them the appearance

-  of having been recently dug up, and then passed them off as

-  specimens of antediluvian creation. Being successful in this, he

-  went the length of arranging a number of bones so as to represent

-  an entire skeleton; and had thus deceived the learned Cuvier. In

-  extenuation of Cuvier’s credulity, it is stated that the bones were

-  so skilfully coloured as to make them look of immense antiquity,

-  and he was not allowed to touch them lest they should crumble to

-  pieces. But when M. Schlegel subjected them to rude handling, he

-  found that they were comparatively modern, and that they were

-  placed one by the other without that profound knowledge of anatomy

-  which was to have been expected from the man bold enough to execute

-  such an audacious fraud.

-

-

-“THE OLDEST PIECE OF WOOD UPON EARTH.”

-

-The most remarkable vegetable relic which the Lower Old Red Sandstone

-has given us is a small fragment of a coniferous tree of the Araucarian

-family, which formed one of the chief ornaments of the late Hugh

-Miller’s museum, and to which he used to point as the oldest piece

-of wood upon earth. He found it in one of the ichthyolite beds of

-Cromarty, and thus refers to it in his _Testimony of the Rocks_:

-

-  On what perished land of the early paleozoic ages did this

-  venerably antique tree cast root and flourish, when the extinct

-  genera Pterichthys and Coccoeteus were enjoying life by millions

-  in the surrounding seas, long ere the flora or fauna of the coal

-  measures had begun to be?

-

-  The same nodule which enclosed this lignite contained part of

-  another fossil, the well-marked scales of _Diplacanthus striatus_,

-  an ichthyolite restricted to the Lower Old Red Sandstone

-  exclusively. If there be any value in paleontological evidence,

-  this Cromarty lignite must have been deposited in a sea inhabited

-  by the Coccoeteus and Diplacanthus. It is demonstrable that, while

-  yet in a recent state, a Diplacanthus lay down and died beside it;

-  and the evidence in the case is unequivocally this, that in the

-  oldest portion of the oldest terrestrial flora yet known there

-  occurs the fragment of a tree quite as high in the scale as the

-  stately Norfolk-Island pine or the noble cedar of Lebanon.

-

-

-NO FOSSIL ROSE.

-

-Professor Agassiz, in a lecture upon the trees of America, states a

-remarkable fact in regard to the family of the rose,--which includes

-among its varieties not only many of the most beautiful flowers, but

-also the richest fruits, as the apple, pear, peach, plum, apricot,

-cherry, strawberry, raspberry, &c.,--namely, that _no fossil plants

-belonging to this family have ever been discovered by geologists_! This

-M. Agassiz regards as conclusive evidence that the introduction of this

-family of plants upon the earth was coeval with, or subsequent to, the

-creation of man, to whose comfort and happiness they seem especially

-designed by a wise Providence to contribute.

-

-

-CHANGES ON THE EARTH’S SURFACE.

-

-In the Imperial Library at Paris is preserved a manuscript work by

-an Arabian writer, Mohammed Karurini, who flourished in the seventh

-century of the Hegira, or at the close of the thirteenth century of

-our era. Herein we find several curious remarks on aerolites and

-earthquakes, and the successive changes of position which the land and

-sea have undergone. Of the latter class is the following beautiful

-passage from the narrative of Khidz, an allegorical personage:

-

-  I passed one day by a very ancient and wonderfully populous city,

-  and asked one of its inhabitants how long it had been founded. “It

-  is indeed a mighty city,” replied he; “we know not how long it

-  has existed, and our ancestors were on this subject as ignorant

-  as ourselves.” Five centuries afterwards, as I passed by the same

-  place, I could not perceive the slightest vestige of the city. I

-  demanded of a peasant who was gathering herbs upon its former site

-  how long it had been destroyed. “In sooth, a strange question,”

-  replied he; “the ground here has never been different from what you

-  now behold it.” “Was there not of old,” said I, “a splendid city

-  here?” “Never,” answered he, “so far as we have seen; and never

-  did our fathers speak to us of any such.” On my return there five

-  hundred years afterwards, _I found the sea in the same place_; and

-  on its shores were a party of fishermen, of whom I inquired how

-  long the land had been covered by the waters. “Is this a question,”

-  say they, “for a man like you? This spot has always been what it is

-  now.” I again returned five hundred years afterwards; the sea had

-  disappeared: I inquired of a man who stood alone upon the spot how

-  long this change had taken place, and he gave me the same answer as

-  I had received before. Lastly, on coming back again after an equal

-  lapse of time, I found there a flourishing city, more populous and

-  more rich in beautiful buildings than the city I had seen the first

-  time; and when I would fain have informed myself concerning its

-  origin, the inhabitants answered me, “Its rise is lost in remote

-  antiquity: we are ignorant how long it has existed, and our fathers

-  were on this subject as ignorant as ourselves.”

-

-This striking passage was quoted in the _Examiner_, in 1834. Surely in

-this fragment of antiquity we trace the “geological changes” of modern

-science.

-

-

-GEOLOGICAL TIME.

-

-Many ingenious calculations have been made to approximate the dates

-of certain geological events; but these, it must be confessed, are

-more amusing than instructive. For example, so many inches of silt are

-yearly laid down in the delta of the Mississippi--how many centuries

-will it have taken to accumulate a thickness of 30, 60, or 100 feet?

-Again, the ledges of Niagara are wasting at the rate of so many feet

-per century--how many years must the river have taken to cut its way

-back from Queenstown to the present Falls? Again, lavas and melted

-basalts cool, according to the size of the mass, at the rate of so many

-degrees in a given time--how many millions of years must have elapsed,

-supposing an original igneous condition of the earth, before its crust

-had attained a state of solidity? or further, before its surface had

-cooled down to the present mean temperature? For these and similar

-computations, the student will at once perceive we want the necessary

-uniformity of factor; and until we can bring elements of calculation as

-exact as those of astronomy to bear on geological chronology, it will

-be better to regard our “eras” and “epochs” and “systems” as so many

-terms, indefinite in their duration, but sufficient for the magnitude

-of the operations embraced within their limits.--_Advanced Textbook of

-Geology, by David Page, F.G.S._

-

-M. Rozet, in 1841, called attention to the fact, that the causes which

-have produced irregularities in the structure of the globe have not yet

-ceased to act, as is proved by earthquakes, volcanic eruptions, slow

-and continuous movements of the crust of the earth in certain regions,

-&c. We may, therefore, yet see repeated the great catastrophes which

-the surface of the earth has undergone anteriorly to the historical

-period.

-

-At the meeting of the British Association in 1855, Mr. Hopkins excited

-much controversy by his startling speculation--that 9000 years ago

-the site on which London now stands was in the torrid zone; and that,

-according to perpetual changes in progress, the whole of England would

-in time arrive within the Arctic circle.

-

-

-CURIOUS CAUSE OF CHANGE OF LEVEL.

-

-Professor Hennessey, in 1857, _found the entire mass of rock and

-hill on which the Armagh Observatory is erected to be slightly, but

-to an astronomer quite perceptibly, tilted or canted, at one season

-to the east, at another to the west_. This he at first attributed to

-the varying power of the sun’s radiation to heat and expand the rock

-throughout the year; but he subsequently had reason to attribute it

-rather to the infiltration of water to the parts where the clay-slate

-and limestone rocks met, the varying quantity of the water exerting

-a powerful hydrostatic energy by which the position of the rock is

-slightly varied.

-

-Now Armagh and its observatory stand at the junction of the mountain

-limestone with the clay-slate, having, as it were, one leg on the

-former and the other on the latter; and both rocks probably reach

-downwards 1000 or 2000 feet. When rain falls, the one will absorb

-more water than the other; both will gain an increase of conductive

-power; but the one which has absorbed most water will have the greatest

-increase, and being thus the better conductor, will _draw a greater

-portion of heat from the hot nucleus below to the surface_--will

-become, in fact, temporarily hotter, and, as a consequence, _expand

-more than the other_. In a word, _both rocks will expand at the wet

-season; but the best conductor, or most absorbent rock, will expand

-most, and seem to tilt the hill to one side; at the dry season it will

-subside most, and the hill will seem to be tilted in the opposite

-direction_.

-

-The fact is curious, and not less so are the results deducible from

-it. First, hills are higher at one season than another; a fact we

-might have supposed, but never could have ascertained by measurement.

-Secondly, they are highest, not, as we should have supposed, at the

-hottest season, but at the wettest. Thirdly, it is from the _different

-rates_ of expansion of different rocks that this has been discovered.

-Fourthly, it is by converse with the _heavens_ that it has been made

-known to us. A variation of probably half a second, or less, in the

-right ascension of three or four stars, observed at different seasons,

-no doubt revealed the fact to the sagacious astronomer of Armagh, and

-even enabled him to divine its cause.

-

-  Professor Hennessey observes in connection with this phenomenon,

-  that a very small change of ellipticity would suffice to lay

-  bare or submerge extensive tracts of the globe. If, for example,

-  the mean ellipticity of the ocean increased from 1/300 to 1/299,

-  the level of the sea would be raised at the equator by about 228

-  feet, while under the parallel of 52° it would be depressed by

-  196 feet. Shallow seas and banks in the latitudes of the British

-  isles, and between them and the pole, would thus be converted into

-  dry land, while low-lying plains and islands near the equator

-  would be submerged. If similar phenomena occurred during early

-  periods of geological history, they would manifestly influence the

-  distribution of land and water during these periods; and with such

-  a direction of the forces as that referred to, they would tend to

-  increase the proportion of land in the polar and temperate regions

-  of the earth, as compared with the equatorial regions during

-  successive geological epochs. Such maps as those published by Sir

-  Charles Lyell on the distribution of land and water in Europe

-  during the Tertiary period, and those of M. Elie de Beaumont,

-  contained in Beaudant’s _Geology_, would, if sufficiently extended,

-  assist in verifying or disproving these views.

-

-

-THE OUTLINES OF CONTINENTS NOT FIXED.

-

-Continents (says M. Agassiz) are only a patchwork formed by the

-emergence and subsidence of land. These processes are still going on

-in various parts of the globe. Where the shores of the continent are

-abrupt and high, the effect produced may be slight, as in Norway and

-Sweden, where a gradual elevation is going on without much alteration

-in their outlines. But if the continent of North America were to be

-depressed 1000 feet, nothing would remain of it except a few islands,

-and any elevation would add vast tracts to its shores.

-

-The west of Asia, comprising Palestine and the country about Ararat and

-the Caspian Sea, is below the level of the ocean, and a rent in the

-mountain-chains by which it is surrounded would transform it into a

-vast gulf.

-

-

-

-

-Meteorological Phenomena.

-

-

-THE ATMOSPHERE.

-

-A philosopher of the East, with a richness of imagery truly oriental,

-describes the Atmosphere as “a spherical shell which surrounds our

-planet to a depth which is unknown to us, by reason of its growing

-tenuity, as it is released from the pressure of its own superincumbent

-mass. Its upper surface cannot be nearer to us than 50, and can

-scarcely be more remote than 500, miles. It surrounds us on all sides,

-yet we see it not; it presses on us with a load of fifteen pounds on

-every square inch of surface of our bodies, or from seventy to one

-hundred tons on us in all, yet we do not so much as feel its weight.

-Softer than the softest down, more impalpable than the finest gossamer,

-it leaves the cobweb undisturbed, and scarcely stirs the lightest

-flower that feeds on the dew it supplies; yet it bears the fleets of

-nations on its wings around the world, and crushes the most refractory

-substances with its weight. When in motion, its force is sufficient to

-level the most stately forests and stable buildings with the earth--to

-raise the waters of the ocean into ridges like mountains, and dash the

-strongest ships to pieces like toys. It warms and cools by turns the

-earth and the living creatures that inhabit it. It draws up vapours

-from the sea and land, retains them dissolved in itself or suspended

-in cisterns of clouds, and throws them down again as rain or dew when

-they are required. It bends the rays of the sun from their path to

-give us the twilight of evening and of dawn; it disperses and refracts

-their various tints to beautify the approach and the retreat of the orb

-of day. But for the atmosphere sunshine would burst on us and fail us

-at once, and at once remove us from midnight darkness to the blaze of

-noon. We should have no twilight to soften and beautify the landscape;

-no clouds to shade us from the searching heat; but the bald earth, as

-it revolved on its axis, would turn its tanned and weakened front to

-the full and unmitigated rays of the lord of day. It affords the gas

-which vivifies and warms our frames, and receives into itself that

-which has been polluted by use and is thrown off as noxious. It feeds

-the flames of life exactly as it does that of the fire--it is in both

-cases consumed and affords the food of consumption--in both cases it

-becomes combined with charcoal, which requires it for combustion and is

-removed by it when this is over.”

-

-

-UNIVERSALITY OF THE ATMOSPHERE.

-

-It is only the girdling, encircling air that flows above and around all

-that makes the whole world kin. The carbonic acid with which to-day

-our breathing fills the air, to-morrow makes its way round the world.

-The date-trees that grow round the falls of the Nile will drink it in

-by their leaves; the cedars of Lebanon will take of it to add to their

-stature; the cocoa-nuts of Tahiti will grow rapidly upon it; and the

-palms and bananas of Japan will change it into flowers. The oxygen we

-are breathing was distilled for us some short time ago by the magnolias

-of the Susquehanna; the great trees that skirt the Orinoco and the

-Amazon, the giant rhododendrons of the Himalayas, contributed to it,

-and the roses and myrtles of Cashmere, the cinnamon-tree of Ceylon, and

-the forest, older than the Flood, buried deep in the heart of Africa,

-far behind the Mountains of the Moon. The rain we see descending was

-thawed for us out of the icebergs which have watched the polar star for

-ages; and the lotus-lilies have soaked up from the Nile, and exhaled as

-vapour, snows that rested on the summits of the Alps.--_North-British

-Review._

-

-

-THE HEIGHT OF THE ATMOSPHERE.

-

-The differences existing between that which appertains to the air

-of heaven (the realms of universal space) and that which belongs to

-the strata of our terrestrial atmosphere are very striking. It is

-not possible, as well-attested facts prove, perfectly to explain

-the operations at work in the much-contested upper boundaries of

-our atmosphere. The extraordinary lightness of whole nights in the

-year 1831, during which small print might be read at midnight in

-the latitudes of Italy and the north of Germany, is a fact directly

-at variance with all we know according to the researches on the

-crepuscular theory and the height of the atmosphere. The phenomena

-of light depend upon conditions still less understood; and their

-variability at twilight, as well as in the zodiacal light, excite our

-astonishment. Yet the atmosphere which surrounds the earth is not

-thicker in proportion to the bulk of our globe than the line of a

-circle two inches in diameter when compared with the space which it

-encloses, or the down on the skin of a peach in comparison with the

-fruit inside.

-

-

-COLOURS OF THE ATMOSPHERE.

-

-Pure air is blue, because, according to Newton, the molecules of the

-air have the thickness necessary to reflect blue rays. When the sky

-is not perfectly pure, and the atmosphere is blended with perceptible

-vapours, the diffused light is mixed with a large proportion of

-white. As the moon is yellow, the blue of the air assumes somewhat

-of a greenish tinge, or, in other words, becomes blended with

-yellow.--_Letter from Arago to Humboldt_; _Cosmos_, vol. iii.

-

-

-BEAUTY OF TWILIGHT.

-

-This phenomenon is caused by the refraction of solar light enabling

-it to diffuse itself gradually over our hemisphere, obscured by the

-shades of night, long before the sun appears, even when that luminary

-is eighteen degrees below our horizon. It is towards the poles that

-this reflected splendour of the great luminary is longest visible,

-often changing the whole of the night into a magic day, of which the

-inhabitants of southern Europe can form no adequate conception.

-

-

-HOW PASCAL WEIGHED THE ATMOSPHERE.

-

-Pascal’s treatise on the weight of the whole mass of air forms the

-basis of the modern science of Pneumatics. In order to prove that the

-mass of air presses by its weight on all the bodies which it surrounds,

-and also that it is elastic and compressible, he carried a balloon,

-half-filled with air, to the top of the Puy de Dome, a mountain about

-500 toises above Clermont, in Auvergne. It gradually inflated itself

-as it ascended, and when it reached the summit it was quite full,

-and swollen as if fresh air had been blown into it; or, what is the

-same thing, it swelled in proportion as the weight of the column of

-air which pressed upon it was diminished. When again brought down it

-became more and more flaccid, and when it reached the bottom it resumed

-its original condition. In the nine chapters of which the treatise

-consists, Pascal shows that all the phenomena and effects hitherto

-ascribed to the horror of a vacuum arise from the weight of the mass

-of air; and after explaining the variable pressure of the atmosphere

-in different localities and in its different states, and the rise of

-water in pumps, he calculates that the whole mass of air round our

-globe weighs 8,983,889,440,000,000,000 French pounds.--_North-British

-Review_, No. 2.

-

-It seems probable, from many indications, that the greatest height at

-which visible clouds _ever exist_ does not exceed ten miles; at which

-height the density of the air is about an eighth part of what it is at

-the level of the sea.--_Sir John Herschel._

-

-

-VARIATIONS OF CLIMATE.

-

-History informs us that many of the countries of Europe which now

-possess very mild winters, at one time experienced severe cold during

-this season of the year. The Tiber, at Rome, was often frozen over, and

-snow at one time lay for forty days in that city. The Euxine Sea was

-frozen over every winter during the time of Ovid, and the rivers Rhine

-and Rhone used to be frozen over so deep that the ice sustained loaded

-wagons. The waters of the Tiber, Rhine, and Rhone, now flow freely

-every winter; ice is unknown in Rome, and the waves of the Euxine dash

-their wintry foam uncrystallised upon the rocks. Some have ascribed

-these climate changes to agriculture--the cutting down of dense

-forests, the exposing of the unturned soil to the summer’s sun, and the

-draining of great marshes. We do not believe that such great changes

-could be produced on the climate of any country by agriculture; and we

-are certain that no such theory can account for the contrary change of

-climate--from warm to cold winters--which history tells us has taken

-place in other countries than those named. Greenland received its name

-from the emerald herbage which once clothed its valleys and mountains;

-and its east coast, which is now inaccessible on account of perpetual

-ice heaped upon its shores, was in the eleventh century the seat of

-flourishing Scandinavian colonies, all trace of which is now lost. Cold

-Labrador was named Vinland by the Northmen, who visited it A.D. 1000,

-and were charmed with its then mild climate. The cause of these changes

-is an important inquiry.--_Scientific American._

-

-

-AVERAGE CLIMATES.

-

-When we consider the numerous and rapid changes which take place in

-our climate, it is a remarkable fact, that _the mean temperature of

-a place remains nearly the same_. The winter may be unusually cold,

-or the summer unusually hot, while the mean temperature has varied

-even less than a degree. A very warm summer is therefore likely to

-be accompanied with a cold winter; and in general, if we have any

-long period of cold weather, we may expect a similar period at a

-higher temperature. In general, however, in the same locality the

-relative distribution over summer and winter undergoes comparatively

-small variations; therefore every point of the globe has an average

-climate, though it is occasionally disturbed by different atmospheric

-changes.--_North-British Review_, No. 49.

-

-

-THE FINEST CLIMATE IN THE WORLD.

-

-Humboldt regards the climate of the Caspian Sea as the most salubrious

-in the world: here he found the most delicious fruits that he saw

-during his travels; and such was the purity of the air, that polished

-steel would not tarnish even by night exposure.

-

-

-THE PUREST ATMOSPHERES.

-

-The cloudless purity and transparency of the atmosphere, which last

-for eight months at Santiago, in Chili, are so great, that Lieutenant

-Gilliss, with the first telescope ever constructed in America, having

-a diameter of seven inches, was clearly able to recognise the sixth

-star in the trapezium of Orion. If we are to rely upon the statements

-of the Rev. Mr. Stoddart, an American missionary, Oroomiah, in Persia,

-seems to be, in so far as regards the transparency of the atmosphere,

-the most suitable place in the world for an astronomical observatory.

-Writing to Sir John Herschel from that country, he mentions that he

-has been enabled to distinguish with the naked eye the satellites

-of Jupiter, the crescent of Venus, the rings of Saturn, and the

-constituent members of several double stars.

-

-

-SEA-BREEZES AND LAND-BREEZES ILLUSTRATED.

-

-When a fire is kindled on the hearth, we may, if we will observe the

-motes floating in the room, see that those nearest the chimney are the

-first to feel the draught and to obey it,--they are drawn into the

-blaze. The circle of inflowing air is gradually enlarged, until it is

-scarcely perceived in the remote parts of the room. Now the land is the

-hearth, the rays of the sun the fire, and the sea, with its cool and

-calm air, the room; and thus we have at our firesides the sea-breeze in

-miniature.

-

-When the sun goes down, the fire ceases; then the dry land commences

-to give off its surplus heat by radiation, so that by nine or ten

-o’clock it and the air above it are cooled below the sea temperature.

-The atmosphere on the land thus becomes heavier than that on the

-sea, and consequently there is a wind seaward, which we call the

-land-breeze.--_Maury._

-

-

-SUPERIOR SALUBRITY OF THE WEST.

-

-All large cities and towns have their best districts in the West;[38]

-which choice the French _savans_, Pelouze, Pouillet, Boussingault, and

-Elie de Beaumont, attribute to the law of atmospheric pressure. “When,”

-say they, “the barometric column rises, smoke and pernicious emanations

-rapidly evaporate in space.” On the contrary, smoke and noxious vapours

-remain in apartments, and on the surface of the soil. Now, of all

-winds, that which causes the greatest ascension of the barometric

-column is the east; and that which lowers it most is the west. When the

-latter blows, it carries with it to the eastern parts of the town all

-the deleterious gases from the west; and thus the inhabitants of the

-east have to support their own smoke and miasma, and those brought by

-western winds. When, on the contrary, the east wind blows, it purifies

-the air by causing to ascend the pernicious emanations which it cannot

-drive to the west. Consequently, the inhabitants of the west receive

-pure air, from whatever part of the horizon it may arrive; and as the

-west winds are most prevalent, they are the first to receive the air

-pure, and as it arrives from the country.

-

-

-FERTILISATION OF CLOUDS.

-

-As the navigator cruises in the Pacific Ocean among the islands of

-the trade-wind region, he sees gorgeous piles of cumuli, heaped up in

-fleecy masses, not only capping the island hills, but often overhanging

-the lowest islet of the tropics, and even standing above coral patches

-and hidden reefs; “a cloud by day.” to serve as a beacon to the lonely

-mariner out there at sea, and to warn him of shoals and dangers which

-no lead nor seaman’s eye has ever seen or sounded. These clouds, under

-favourable circumstances, may be seen gathering above the low coral

-island, preparing it for vegetation and fruitfulness in a very striking

-manner. As they are condensed into showers, one fancies that they are

-a sponge of the most exquisite and delicately elaborated material, and

-that he can see, as they “drop down their fatness,” the invisible but

-bountiful hand aloft that is pressing and squeezing it out.--_Maury._

-

-

-BAROMETRIC MEASUREMENT.

-

-We must not place too implicit a dependence on Barometrical

-Measurements. Ermann in Siberia, and Ross in the Antarctic Seas, have

-demonstrated the existence of localities on the earth’s surface where

-a permanent depression of the barometer prevails to the astonishing

-extent of nearly an inch.

-

-

-GIGANTIC BAROMETER.

-

-In the Great Exhibition Building of 1851 was a colossal Barometer, the

-tube and scale reaching from the floor of the gallery nearly to the top

-of the building, and the rise and fall of the indicating fluid being

-marked by feet instead of by tenths of inches. The column of mercury,

-supported by the pressure of the atmosphere, communicated with a

-perpendicular tube of smaller bore, which contained a coloured fluid

-much lighter than mercury. When a diminution of atmospheric pressure

-occurred, the mercury in the large tube descended, and by its fall

-forced up the coloured fluid in the smaller tube; the fall of the one

-being indicated in a magnified ratio by the rise in the other.

-

-

-THE ATMOSPHERE COMPARED TO A STEAM-ENGINE.

-

-In this comparison, by Lieut. Maury, the South Seas themselves, in all

-their vast intertropical extent, are the boiler for the engine, and the

-northern hemisphere is its condenser. The mechanical power exerted by

-the air and the sun in lifting water from the earth, in transporting

-it from one place to another, and in letting it down again, is

-inconceivably great. The utilitarian who compares the water-power that

-the Falls of Niagara would afford if applied to machinery is astonished

-at the number of figures which are required to express its equivalent

-in horse-power. Yet what is the horse-power of the Niagara, falling

-a few steps, in comparison with the horse-power that is required to

-lift up as high as the clouds and let down again all the water that is

-discharged into the sea, not only by this river, but by all the other

-rivers in the world? The calculation has been made by engineers; and

-according to it, the force of making and lifting vapour from each area

-of one acre that is included on the surface of the earth, is equal to

-the power of thirty horses; and for the whole of the earth, it is 800

-times greater than all the water-power in Europe.

-

-

-HOW DOES THE RAIN-MAKING VAPOUR GET FROM THE SOUTHERN INTO THE NORTHERN

-HEMISPHERE?

-

-This comes with such regularity, that our rivers never go dry, and

-our springs fail not, because of the exact _compensation_ of the

-grand machine of _the atmosphere_. It is exquisitely and wonderfully

-counterpoised. Late in the autumn of the north, throughout its

-winter, and in early spring, the sun is pouring his rays with the

-greatest intensity down upon the seas of the southern hemisphere; and

-this powerful engine, which we are contemplating, is pumping up the

-water there with the greatest activity; at the same time, the mean

-temperature of the entire southern hemisphere is about 10° higher than

-the northern. The heat which this heavy evaporation absorbs becomes

-latent, and with the moisture is carried through the upper regions

-of the atmosphere until it reaches our climates. Here the vapour is

-formed into clouds, condensed and precipitated; the heat which held

-their water in the state of vapour is set free, and becomes sensible

-heat; and it is that which contributes so much to temper our winter

-climate. It clouds up in winter, turns warm, and we say we are going

-to have falling weather: that is because the process of condensation

-has already commenced, though no rain or snow may have fallen. Thus we

-feel this southern heat, that has been collected by the rays of the sun

-by the sea, been bottled away by the winds in the clouds of a southern

-summer, and set free in the process of condensation in our northern

-winter.

-

-Thus the South Seas should supply mainly the water for the engine just

-described, while the northern hemisphere condenses it; we should,

-therefore, have more rain in the northern hemisphere. The rivers tell

-us that we have, at least on the land; for the great water-courses of

-the globe, and half the fresh water in the world, are found on the

-north side of the equator. This fact is strongly corroborative of this

-hypothesis. To evaporate water enough annually from the ocean to cover

-the earth, on the average, five feet deep with rain; to transport it

-from one zone to another; and to precipitate it in the right places at

-suitable times and in the proportions due,--is one of the offices of

-the grand atmospherical machine. This water is evaporated principally

-from the torrid zone. Supposing it all to come thence, we shall have

-encircling the earth a belt of ocean 3000 miles in breadth, from which

-this atmosphere evaporates a layer of water annually sixteen feet in

-depth. And to hoist up as high as the clouds, and lower down again,

-all the water, in a lake sixteen feet deep and 3000 miles broad and

-24,000 long, is the yearly business of this invisible machinery. What a

-powerful engine is the atmosphere! and how nicely adjusted must be all

-the cogs and wheels and springs and _compensations_ of this exquisite

-piece of machinery, that it never wears out nor breaks down, nor fails

-to do its work at the right time and in the right way!--_Maury._

-

-

-THE PHILOSOPHY OF RAIN.

-

-To understand the philosophy of this beautiful and often sublime

-phenomenon, a few facts derived from observation and a long train of

-experiments must be remembered.

-

-  1. Were the atmosphere every where at all times at a uniform

-  temperature, we should never have rain, or hail, or snow. The water

-  absorbed by it in evaporation from the sea and the earth’s surface

-  would descend in an imperceptible vapour, or cease to be absorbed

-  by the air when it was once fully saturated.

-

-  2. The absorbing power of the atmosphere, and consequently its

-  capability to retain humidity, is proportionally greater in warm

-  than in cold air.

-

-  3. The air near the surface of the earth is warmer than it is in

-  the region of the clouds. The higher we ascend from the earth, the

-  colder do we find the atmosphere. Hence the perpetual snow on very

-  high mountains in the hottest climate.

-

-Now when, from continued evaporation, the air is highly saturated

-with vapour, though it be invisible and the sky cloudless, if its

-temperature is suddenly reduced by cold currents descending from

-above or rushing from a higher to a lower latitude, its capacity to

-retain moisture is diminished, clouds are formed, and the result is

-rain. Air condenses as it cools, and, like a sponge filled with water

-and compressed, pours out the water which its diminished capacity

-cannot hold. What but Omniscience could have devised such an admirable

-arrangement for watering the earth?

-

-

-INORDINATE RAINY CLIMATE.

-

-The climate of the Khasia mountains, which lie north-east from

-Calcutta, and are separated by the valley of the Burrampooter River

-from the Himalaya range, is remarkable for the inordinate fall of

-rain--the greatest, it is said, which has ever been recorded. Mr. Yule,

-an English gentleman, established that in the single month of August

-1841 there fell 264 inches of rain, or 22 feet, of which 12½ feet

-fell in the space of five consecutive days. This astonishing fact is

-confirmed by two other English travellers, who measured 30 inches of

-rain in twenty-four hours, and during seven months above 500 inches.

-This great rain-fall is attributed to the abruptness of the mountains

-which face the Bay of Bengal, and the intervening flat swamps 200 miles

-in extent. The district of the excessive rain is extremely limited; and

-but a few degrees farther west, rain is said to be almost unknown, and

-the winter falls of snow to seldom exceed two inches.

-

-

-HOW DOES THE NORTH WIND DRIVE AWAY RAIN?

-

-We may liken it to a wet sponge, and the decrease of temperature

-to the hand that squeezes that sponge. Finally, reaching the cold

-latitudes, all the moisture that a dew-point of zero, and even far

-below, can extract, is wrung from it; and this air then commences “to

-return according to his circuits” as dry atmosphere. And here we can

-quote Scripture again: “The north wind driveth away rain.” This is a

-meteorological fact of high authority and great importance in the study

-of the circulation of the atmosphere.--_Maury._

-

-

-SIZE OF RAIN-DROPS.

-

-The Drops of Rain vary in their size, perhaps from the 25th to the ¼ of

-an inch in diameter. In parting from the clouds, they precipitate their

-descent till the increasing resistance opposed by the air becomes equal

-to their weight, when they continue to fall with uniform velocity. This

-velocity is, therefore, in a certain ratio to the diameter of the

-drops; hence thunder and other showers in which the drops are large

-pour down faster than a drizzling rain. A drop of the 25th part of an

-inch, in falling through the air, would, when it had arrived at its

-uniform velocity, only acquire a celerity of 11½ feet per second; while

-one of ¼ of an inch would equal a velocity of 33½ feet.--_Leslie._

-

-

-RAINLESS DISTRICTS.

-

-In several parts of the world there is no rain at all. In the Old World

-there are two districts of this kind: the desert of Sahara in Africa,

-and in Asia part of Arabia, Syria, and Persia; the other district lies

-between north latitude 30° and 50°, and between 75° and 118° of east

-longitude, including Thibet, Gobiar Shama, and Mongolia. In the New

-World the rainless districts are of much less magnitude, occupying two

-narrow strips on the shores of Peru and Bolivia, and on the coast of

-Mexico and Guatemala, with a small district between Trinidad and Panama

-on the coast of Venezuela.

-

-

-ALL THE RAIN IN THE WORLD.

-

-The Pacific Ocean and the Indian Ocean may be considered as one sheet

-of water covering an area quite equal in extent to one half of that

-embraced by the whole surface of the earth; and the total annual fall

-of rain on the earth’s surface is 186,240 cubic imperial miles. Not

-less than three-fourths of the vapour which makes this rain comes from

-this waste of waters; but, supposing that only half of this quantity,

-that is 93,120 cubic miles of rain, falls upon this sea, and that that

-much at least is taken up from it again as vapour, this would give

-255 cubic miles as the quantity of water which is daily lifted up and

-poured back again into this expanse. It is taken up at one place,

-and rained down at another; and in this process, therefore, we have

-agencies for multitudes of partial and conflicting currents, all, in

-their set strength, apparently as uncertain as the winds.

-

-The better to appreciate the operation of such agencies in producing

-currents in the sea, imagine a district of 255 square miles to be set

-apart in the midst of the Pacific Ocean as the scene of operations

-for one day; then conceive a machine capable of pumping up in the

-twenty-four hours all the water to the depth of one mile in this

-district. The machine must not only pump up and bear off this immense

-quantity of water, but it must discharge it again into the sea on the

-same day, but at some other place.

-

-All the great rivers of America, Europe, and Asia are lifted up by the

-atmosphere, and flow in invisible streams back through the air to their

-sources among the hills; and through channels so regular, certain, and

-well defined, that the quantity thus conveyed one year with the other

-is nearly the same: for that is the quantity which we see running down

-to the ocean through these rivers; and the quantity discharged annually

-by each river is, as far as we can judge, nearly a constant.--_Maury._

-

-

-AN INCH OF RAIN ON THE ATLANTIC.

-

-Lieutenant Maury thus computes the effect of a single Inch of Rain

-falling upon the Atlantic Ocean. The Atlantic includes an area of

-twenty-five millions of square miles. Suppose an inch of rain to fall

-upon only one-fifth of this vast expanse. It would weigh, says our

-author, three hundred and sixty thousand millions of tons: and the salt

-which, as water, it held in solution in the sea, and which, when that

-water was taken up as vapour, was left behind to disturb equilibrium,

-weighed sixteen millions more of tons, or nearly twice as much as all

-the ships in the world could carry at a cargo each. It might fall in

-an hour, or it might fall in a day; but, occupy what time it might

-in falling, this rain is calculated to exert so much force--which is

-inconceivably great--in disturbing the equilibrium of the ocean. If

-all the water discharged by the Mississippi river during the year were

-taken up in one mighty measure, and cast into the ocean at one effort,

-it would not make a greater disturbance in the equilibrium of the

-sea than would the fall of rain supposed. And yet so gentle are the

-operations of nature, that movements so vast are unperceived.

-

-

-THE EQUATORIAL CLOUD-RING.

-

-In crossing the Equatorial Doldrums, the voyager passes a ring of

-clouds that encircles the earth, and is stretched around our planet

-to regulate the quantity of precipitation in the rain-belt beneath

-it; to preserve the due quantum of heat on the face of the earth; to

-adjust the winds; and send out for distribution to the four corners

-vapours in proper quantities, to make up to each river-basin, climate,

-and season, its quota of sunshine, cloud, and moisture. Like the

-balance-wheel of a well-constructed chronometer, this cloud-ring

-affords the grand atmospherical machine the most exquisitely arranged

-_self-compensation_. Nature herself has hung a thermometer under this

-cloud-belt that is more perfect than any that man can construct, and

-its indications are not to be mistaken.--_Maury._

-

-

-“THE EQUATORIAL DOLDRUMS”

-

-is another of these calm places. Besides being a region of calms and

-baffling winds, it is a region noted for its rains and clouds, which

-make it one of the most oppressive and disagreeable places at sea. The

-emigrant ships from Europe for Australia have to cross it. They are

-often baffled in it for two or three weeks; then the children and the

-passengers who are of delicate health suffer most. It is a frightful

-graveyard on the wayside to that golden land.

-

-

-BEAUTY OF THE DEW-DROP.

-

-The Dew-drop is familiar to every one from earliest infancy. Resting

-in luminous beads on the down of leaves, or pendent from the finest

-blades of grass, or threaded upon the floating lines of the gossamer,

-its “orient pearl” varies in size from the diameter of a small pea to

-the most minute atom that can be imagined to exist. Each of these, like

-the rain-drops, has the properties of reflecting and refracting light;

-hence, from so many minute prisms, the unfolded rays of the sun are

-sent up to the eye in colours of brilliancy similar to those of the

-rainbow. When the sunbeams traverse horizontally a very thickly-bedewed

-grass-plot, these colours arrange themselves so as to form an iris,

-or dew-bow; and if we select any one of these drops for observation,

-and steadily regard it while we gradually change our position, we

-shall find the prismatic colours follow each other in their regular

-order.--_Wells._

-

-

-FALL OF DEW IN ONE YEAR.

-

-The annual average quantity of Dew deposited in this country is

-estimated at a depth of about five inches, being about one-seventh

-of the mean quantity of moisture supposed to be received from the

-atmosphere all over Great Britain in the year; or about 22,161,337,355

-tons, taking the ton at 252 imperial gallons.--_Wells._

-

-

-GRADUATED SUPPLY OF DEW TO VEGETATION.

-

-Each of the different grasses draws from the atmosphere during the

-night a supply of dew to recruit its energies dependent upon its form

-and peculiar radiating power. Every flower has a power of radiation

-of its own, subject to changes during the day and night, and the

-deposition of moisture on it is regulated by the peculiar law which

-this radiating power obeys; and this power will be influenced by

-the aspect which the flower presents to the sky, unfolding to the

-contemplative mind the most beautiful example of creative wisdom.[39]

-

-

-WARMTH OF SNOW IN ARCTIC LATITUDES.

-

-The first warm Snows of August and September (says Dr. Kane), falling

-on a thickly-bleached carpet of grasses, heaths, and willows, enshrine

-the flowery growths which nestle round them in a non-conducting air

-chamber; and as each successive snow increases the thickness of the

-cover, we have, before the intense cold of winter sets in, a light

-cellular bed covered by drift, seven, eight, or ten feet deep, in which

-the plant retains its vitality. Dr. Kane has proved by experiments that

-the conducting power of the snow is proportioned to its compression

-by winds, rains, drifts, and congelation. The drifts that accumulate

-during nine months of the year are dispersed in well-defined layers

-of different density. We have first the warm cellular snows of fall,

-which surround the plant; next the finely-impacted snow-dust of winter;

-and above these the later humid deposits of spring. In the earlier

-summer, in the inclined slopes that face the sun, as the upper snow is

-melted and sinks upon the more compact layer below it is to a great

-extent arrested, and runs off like rain from a slope of clay. The plant

-reposes thus in its cellular bed, safe from the rush of waters, and

-protected from the nightly frosts by the icy roof above it.

-

-

-IMPURITY OF SNOW.

-

-It is believed that in ascending mountains difficult breathing is

-sooner felt upon snow than upon rock; and M. Boussingault, in his

-account of the ascent of Chimborazo, attributes this to the sensible

-deficiency of oxygen contained in the pores of the snow, which is

-exhaled when it melts. The fact that the air absorbed by snow is

-impure, was ascertained by De Saussure, and has been confirmed by

-Boussingault’s experiments.--_Quarterly Review_, No. 202.

-

-

-SNOW PHENOMENON.

-

-Professor Dove of Berlin relates, in illustration of the formation of

-clouds of Snow over plains situated at a distance from the cooling

-summits of mountains, that on one occasion a large company had gathered

-in a ballroom in Sweden. It was one of those icy starlight nights

-which in that country are so aptly called “iron nights.” The weather

-was clear and cold, and the ballroom was clear and warm; and the heat

-was so great, that several ladies fainted. An officer present tried to

-open a window; but it was frozen fast to the sill. As a last resort, he

-broke a pane of glass; the cold air rushed in, and it _snowed in the

-room_. A minute before all was clear; but the warm air of the room had

-sustained an amount of moisture in a transparent condition which it was

-not able to maintain when mixed with the colder air from without. The

-vapour was first condensed, and then frozen.

-

-

-ABSENCE OF SNOW IN SIBERIA.

-

-There is in Siberia, M. Ermann informs us, an _entire district_ in

-which during the winter the sky is constantly clear, and where a single

-particle of snow never falls.--_Arago._

-

-

-ACCURACY OF THE CHINESE AS OBSERVERS.

-

-The beautiful forms of snow-crystals have long since attracted Chinese

-observers; for from a remote period there has been met with in their

-conversation and books an axiomatic expression, to the effect that

-“snow-flakes are hexagonal,” showing the Chinese to be accurate

-observers of nature.

-

-

-PROTECTION AGAINST HAIL AND STORMS.

-

-Arago relates, that when, in 1847, two small agricultural districts

-of Bourgoyne had lost by Hail crops to the value of a million and a

-half of francs, certain of the proprietors went to consult him on the

-means of protecting them from like disasters. Resting on the hypothesis

-of the electric origin of hail, Arago suggested the discharge of

-the electricity of the clouds by means of balloons communicating by

-a metallic wire with the soil. This project was not carried out;

-but Arago persisted in believing in the effectiveness of the method

-proposed.

-

-  Arago, in his _Meteorological Essays_, inquires whether the firing

-  of cannon can dissipate storms. He cites several cases in its

-  favour, and others which seem to oppose it; but he concludes by

-  recommending it to his successors. Whilst Arago was propounding

-  these questions, a person not conversant with science, the poet

-  Méry, was collecting facts supporting the view, which he has

-  published in his _Paris Futur_. His attention was attracted to the

-  firing of cannon to dissipate storms in 1828, whilst an assistant

-  in the “Ecole de Tir” at Vincennes. Having observed that there was

-  never any rain in the morning of the exercise of firing, he waited

-  to examine military records, and found there, as he says, facts

-  which justified the expressions of “Le soleil d’Austerlitz,” “Le

-  soleil de juillet,” upon the morning of the Revolution of July;

-  and he concluded by proposing to construct around Paris twelve

-  towers of great height, which he calls “tours imbrifuges,” each

-  carrying 100 cannons, which should be discharged into the air on

-  the approach of a storm. About this time an incident occurred which

-  in nowise confirmed the truth of M. Méry’s theory. The 14th of

-  August was a fine day. On the 15th, the fête of the Empire, the

-  sun shone out, the cannon thundered all day long, fireworks and

-  illuminations were blazing from nine o’clock in the evening. Every

-  thing conspired to verify the hypothesis of M. Méry, and chase

-  away storms for a long time. But towards eleven in the evening

-  a torrent of rain burst upon Paris, in spite of the pretended

-  influence of the discharge of cannon, and gave an occasion for the

-  mobile Gallic mind to turn its attention in other directions.

-

-

-TERRIFIC HAILSTORM.

-

-Jansen describes, from the log-book of the _Rhijin_, Captain Brandligt,

-in the South-Indian Ocean (25° south latitude) a Hurricane, accompanied

-by Hail, by which several of the crew were made blind, others had their

-faces cut open, and those who were in the rigging had their clothes

-torn off them. The master of the ship compared the sea “to a hilly

-landscape in winter covered with snow.” Does it not appear as if the

-“treasures of the hail” were opened, which were “reserved against the

-time of trouble, against the day of battle and war”?

-

-

-HOW WATERSPOUTS ARE FORMED IN THE JAVA SEA.

-

-Among the small groups of islands in this sea, in the day and night

-thunderstorms, the combat of the clouds appears to make them more

-thirsty than ever. In tunnel form, when they can no longer quench their

-thirst from the surrounding atmosphere, they descend near the surface

-of the sea, and appear to lap the water directly up with their black

-mouths. They are not always accompanied by strong winds; frequently

-more than one is seen at a time, whereupon the clouds whence they

-proceed disperse, and the ends of the Waterspouts bending over finally

-causes them to break in the middle. They seldom last longer than five

-minutes. As they are going away, the bulbous tube, which is as palpable

-as that of a thermometer, becomes broader at the base; and little

-clouds, like steam from the pipe of a locomotive, are continually

-thrown off from the circumference of the spout, and gradually the water

-is released, and the cloud whence the spout came again closes its mouth.

-

-

-COLD IN HUDSON’S BAY.

-

-Mr. R. M. Ballantyne, in his journal of six years’ residence in the

-territories of the Hudson’s Bay Company, tells us, that for part of

-October there is sometimes a little warm, or rather thawy, weather; but

-after that, until the following April, the thermometer seldom rises

-to the freezing point. In the depth of winter, the thermometer falls

-from 30° to 40°, 45°, and even 49° _below zero_ of Fahrenheit. This

-intense cold is not, however, so much felt as one might suppose; for

-during its continuance the air is perfectly calm. Were the slightest

-breath of wind to rise when the thermometer stands so low, no man could

-show his face to it for a moment. Forty degrees below zero, and quite

-calm, is infinitely preferable to fifteen below, or thereabout, with

-a strong breeze of wind. Spirit of wine is, of course, the only thing

-that can be used in the thermometer; as mercury, were it exposed to

-such cold, would remain frozen nearly half the winter. Spirit never

-froze in any cold ever experienced at York Factory, unless when very

-much adulterated with water; and even then the spirit would remain

-liquid in the centre of the mass. Quicksilver easily freezes in this

-climate, and it has frequently been run into a bullet-mould, exposed to

-the cold air till frozen, and in this state rammed down a gun-barrel,

-and fired through a thick plank. The average cold may be set down at

-about 15° or 16° below zero, or 48° of frost. The houses at the Bay are

-built of wood, with double windows and doors. They are heated by large

-iron stoves, fed with wood; yet so intense is the cold, that when a

-stove has been in places red-hot, a basin of water in the room has been

-frozen solid.

-

-

-PURITY OF WENHAM-LAKE ICE.

-

-Professor Faraday attributes the purity of Wenham-Lake Ice to its being

-free from air-bubbles and from salts. The presence of the first makes

-it extremely difficult to succeed in making a lens of English ice which

-will concentrate the solar rays, and readily fire gunpowder; whereas

-nothing is easier than to perform this singular feat of igniting

-a combustible body by aid of a frozen mass if Wenham-Lake ice be

-employed. The absence of salts conduces greatly to the permanence of

-the ice; for where water is so frozen that the salts expelled are still

-contained in air-cavities and cracks, or form thin films between the

-layers of ice, these entangled salts cause the ice to melt at a lower

-temperature than 32°, and the liquefied portions give rise to streams

-and currents within the body of the ice which rapidly carry heat to the

-interior. The mass then goes on thawing within as well as without, and

-at temperatures below 32°; whereas pure, compact, Wenham-Lake ice can

-only thaw at 32°, and only on the outside of the mass.--_Sir Charles

-Lyell’s Second Visit to the United States._

-

-

-ARCTIC TEMPERATURES.

-

-Dr. Kane, in his Second Arctic Expedition, found the thermometers

-beginning to show unexampled temperature: they ranged from 60° to 70°

-below zero, and upon the taffrail of the brig 65°. The reduced mean of

-the best spirit-standards gave 67° or 99° below the freezing point of

-water. At these temperatures chloric ether became solid, and chloroform

-exhibited a granular pellicle on its surface. Spirit of naphtha froze

-at 54°, and the oil of turpentine was solid at 63° and 65°.

-

-

-DR. RAE’S ARCTIC EXPLORATIONS.

-

-The gold medal of the Royal Geographical Society was in 1852 most

-rightfully awarded to this indefatigable Arctic explorer. His survey of

-the inlet of Boothia, in 1848, was unique in its kind. In Repulse Bay

-he maintained his party on deer, principally shot by himself; and spent

-ten months of an Arctic winter in a hut of stones, with no other fuel

-than a kind of hay of the _Andromeda tetragona_. Thus he preserved his

-men to execute surveying journeys of 1000 miles in the spring. Later he

-travelled 300 miles on snow-shoes. In a spring journey over the ice,

-with a pound of fat daily for fuel, accompanied by two men only, and

-trusting solely for shelter to snow-houses, which he taught his men to

-build, he accomplished 1060 miles in thirty-nine days, or twenty-seven

-miles per day, including stoppages,--a feat never equalled in Arctic

-travelling. In the spring journey, and that which followed in the

-summer in boats, 1700 miles were traversed in eighty days. Dr. Rae’s

-greatest sufferings, he once remarked to Sir George Back, arose from

-his being obliged to sleep upon his frozen mocassins in order to thaw

-them for the morning’s use.

-

-

-PHENOMENA OF THE ARCTIC CLIMATE.

-

-Sir John Richardson, in his history of his Expedition to these regions,

-describes the power of the sun in a cloudless sky to have been so

-great, that he was glad to take shelter in the water while the crews

-were engaged on the portages; and he has never felt the direct rays of

-the sun so oppressive as on some occasions in the high latitudes. Sir

-John observes:

-

-  The rapid evaporation of both snow and ice in the winter and

-  spring, long before the action of the sun has produced the

-  slightest thaw or appearance of moisture, is evident by many

-  facts of daily occurrence. Thus when a shirt, after being washed,

-  is exposed in the open air to a temperature of from 40° to 50°

-  below zero, it is instantly rigidly frozen, and may be broken if

-  violently bent. If agitated when in this condition by a strong

-  wind, it makes a rustling noise like theatrical thunder.

-

-  In consequence of the extreme dryness of the atmosphere in winter,

-  most articles of English manufacture brought to Rupert’s Land are

-  shrivelled, bent, and broken. The handles of razors and knives,

-  combs, ivory scales, &c., kept in the warm room, are changed in

-  this way. The human body also becomes vividly electric from the

-  dryness of the skin. One cold night I rose from my bed, and was

-  going out to observe the thermometer, with no other clothing than

-  my flannel night-dress, when on my hand approaching the iron latch

-  of the door, a distinct spark was elicited. Friction of the skin at

-  almost all times in winter produced the electric odour.

-

-  Even at midwinter we had but three hours and a half of daylight.

-  On December 20th I required a candle to write at the window at ten

-  in the morning. The sun was absent ten days, and its place in the

-  heavens at noon was denoted by rays of light shooting into the sky

-  above the woods.

-

-  The moon in the long nights was a most beautiful object, that

-  satellite being constantly above the horizon for nearly a fortnight

-  together. Venus also shone with a brilliancy which is never

-  witnessed in a sky loaded with vapours; and, unless in snowy

-  weather, our nights were always enlivened by the beams of the

-  aurora.

-

-

-INTENSE HEAT AND COLD OF THE DESERT.

-

-Among crystalline bodies, rock-crystal, or silica, is the best

-conductor of heat. This fact accounts for the steadiness of temperature

-in one set district, and the extremes of Heat and Cold presented by

-day and night on such sandy wastes as the Sahara. The sand, which is

-for the most part silica, drinks-in the noon-day heat, and loses it by

-night just as speedily.

-

-The influence of the hot winds from the Sahara has been observed

-in vessels traversing the Atlantic at a distance of upwards of

-1100 geographical miles from the African shores, by the coating of

-impalpable dust upon the sails.

-

-

-TRANSPORTING POWER OF WINDS.

-

-The greatest example of their power is the _sand-flood_ of Africa,

-which, moving gradually eastward, has overwhelmed all the land capable

-of tillage west of the Nile, unless sheltered by high mountains, and

-threatens ultimately to obliterate the rich plain of Egypt.

-

-

-EXHILARATION IN ASCENDING MOUNTAINS.

-

-At all elevations of from 6000 to 11,000 feet, and not unfrequently

-for even 2000 feet more, the pedestrian enjoys a pleasurable feeling,

-imparted by the consciousness of existence, similar to that which is

-described as so fascinating by those who have become familiar with the

-desert-life of the East. The body seems lighter, the nervous power

-greater, the appetite is increased; and fatigue, though felt for a

-time, is removed by the shortest repose. Some travellers have described

-the sensation by the impression that they do not actually press the

-ground, but that the blade of a knife could be inserted between the

-sole of the foot and the mountain top.--_Quarterly Review_, No. 202.

-

-

-TO TELL THE APPROACH OF STORMS.

-

-The proximity of Storms has been ascertained with accuracy by

-various indications of the electrical state of the atmosphere. Thus

-Professor Scott, of Sandhurst College, observed in Shetland that

-drinking-glasses, placed in an inverted position upon a shelf in a

-cupboard on the ground-floor of Belmont House, occasionally emitted

-sounds as if they were tapped with a knife, or raised a little and

-then let fall on the shelf. These sounds preceded wind; and when they

-occurred, boats and vessels were immediately secured. The strength of

-the sound is said to be proportioned to the tempest that follows.

-

-

-REVOLVING STORMS.

-

-By the conjoint labours of Mr. Redfield, Colonel Reid, and Mr.

-Piddington, on the origin and nature of hurricanes, typhoons, or

-revolving storms, the following important results have been obtained.

-Their existence in moderate latitudes on both sides the equator; their

-absence in the immediate neighbourhood of the equatorial regions; and

-the fact, that while in the northern latitudes these storms revolve

-in a direction contrary to the hands of a watch the face of which is

-placed upwards, in the southern latitudes they rotate in the opposite

-direction,--are shown to be so many additions to the long chain of

-evidence by which the rotation of the earth as a physical fact is

-demonstrated.

-

-

-IMPETUS OF A STORM.

-

-Captain Sir S. Brown estimates, from experiments made by him at the

-extremity of the Brighton-Chain Pier in a heavy south-west gale, that

-the waves impinge on a cylindrical surface one foot high and one foot

-in diameter with a force equal to eighty pounds, to which must be added

-that of the wind, which in a violent storm exerts a pressure of forty

-pounds. He computed the collective impetus of the waves on the lower

-part of a lighthouse proposed to be built on the Wolf Rock (exposed

-to the most violent storms of the Atlantic), of the surf on the upper

-part, and of the wind on the whole, to be equal to 100 tons.

-

-

-HOW TO MAKE A STORM-GLASS.

-

-This instrument consists of a glass tube, sealed at one end, and

-furnished with a brass cap at the other end, through which the air

-is admitted by a very small aperture. Nearly fill the tube with the

-following solution: camphor, 2½ drams; nitrate of potash, 38 grains;

-muriate of ammonia, 38 grains; water, 9 drams; rectified spirit,

-9 drams. Dissolve with heat. At the ordinary temperature of the

-atmosphere, plumose crystals are formed. On the approach of stormy

-weather, these crystals appear compressed into a compact mass at the

-bottom of the tube; while during fine weather they assume their plumose

-character, and extend a considerable way up the glass. These results

-depend upon the condition of the air, but they are not considered to

-afford any reliable indication of approaching weather.

-

-

-SPLENDOUR OF THE AURORA BOREALIS.

-

-Humboldt thus beautifully describes this phenomenon:

-

-  The intensity of this light is at times so great, that Lowenörn

-  (on June 29, 1786) recognised its coruscation in bright sunshine.

-  Motion renders the phenomenon more visible. Round the point in

-  the vault of heaven which corresponds to the direction of the

-  inclination of the needle the beams unite together to form the

-  so-called corona, the crown of the Northern Light, which encircles

-  the summit of the heavenly canopy with a milder radiance and

-  unflickering emanations of light. It is only in rare instances that

-  a perfect crown or circle is formed; but on its completion, the

-  phenomenon has invariably reached its maximum, and the radiations

-  become less frequent, shorter, and more colourless. The crown, and

-  the luminous arches break up; and the whole vault of heaven becomes

-  covered with irregularly scattered, broad, faint, almost ashy-gray,

-  luminous, immovable patches, which in their turn disappear, leaving

-  nothing but a trace of a dark smoke-like segment on the horizon.

-  There often remains nothing of the whole spectacle but a white

-  delicate cloud with feathery edges, or divided at equal distances

-  into small roundish groups like cirro-cumuli.--_Cosmos_, vol. i.

-

-Among many theories of this phenomenon is that of Lieutenant Hooper,

-R.N., who has stated to the British Association that he believes “the

-Aurora Borealis to be no more nor less than the moisture in some

-shape (whether dew or vapour, liquid or frozen), illuminated by the

-heavenly bodies, either directly, or reflecting their rays from the

-frozen masses around the Pole, or even from the immediately proximate

-snow-clad earth.”

-

-

-VARIETIES OF LIGHTNING.

-

-According to Arago’s investigations, the evolution of Lightning is of

-three kinds: zigzag, and sharply defined at the edges; in sheets of

-light, illuminating a whole cloud, which seems to open and reveal the

-light within it; and in the form of fire-balls. The duration of the

-first two kinds scarcely continues the thousandth part of a second; but

-the globular lightning moves much more slowly, remaining visible for

-several seconds.

-

-

-WHAT IS SHEET-LIGHTNING?

-

-This electric phenomenon is unaccompanied by thunder, or too distant to

-be heard: when it appears, the whole sky, but particularly the horizon,

-is suddenly illuminated with a flickering flash. Philosophers differ

-much as to its cause. Matteucci supposes it to be produced either

-during evaporation, or evolved (according to Pouillet’s theory) in the

-process of vegetation; or generated by chemical action in the great

-laboratory of nature, the earth, and accumulated in the lower strata of

-the air in consequence of the ground being an imperfect conductor.

-

-  Arago and Kamtz, however, consider sheet-lightning as _reflections

-  of distant thunderstorms_. Saussure observed sheet-lightning in the

-  direction of Geneva, from the Hospice du Grimsel, on the 10th and

-  11th of July 1783; while at the same time a terrific thunderstorm

-  raged at Geneva. Howard, from Tottenham, near London, on July 31,

-  1813, saw sheet-lightning towards the south-east, while the sky was

-  bespangled with stars, not a cloud floating in the air; at the same

-  time a thunderstorm raged at Hastings, and in France from Calais

-  to Dunkirk. Arago supports his opinion, that the phenomenon is

-  _reflected lightning_, by the following illustration: In 1803, when

-  observations were being made for determining the longitude, M. de

-  Zach, on the Brocken, used a few ounces of gunpowder as a signal,

-  the flash of which was visible from the Klenlenberg, sixty leagues

-  off, although these mountains are invisible from each other.

-

-

-PRODUCTION OF LIGHTNING BY RAIN.

-

-A sudden gust of rain is almost sure to succeed a violent detonation

-immediately overhead. Mr. Birt, the meteorologist, asks: Is this rain a

-_cause_ or _consequence_ of the electric discharge? To this he replies:

-

-  In the sudden agglomeration of many minute and feebly electrified

-  globules into one rain-drop, the quantity of electricity is

-  increased in a greater proportion than the surface over which

-  (according to the laws of electric distribution) it is spread. By

-  tension, therefore, it is increased, and may attain the point when

-  it is capable of separating from the _drop_ to seek the surface of

-  the _cloud_, or of the newly-formed descending body of rain, which,

-  under such circumstances, may be regarded as a conducting medium.

-  Arrived at this surface, the tension, for the same reason, becomes

-  enormous, and a flash escapes. This theory Mr. Birt has confirmed

-  by observation of rain in thunderstorms.

-

-

-SERVICE OF LIGHTNING-CONDUCTORS.

-

-Sir David Brewster relates a remarkable instance of a tree in

-Clandeboye Park, in a thick mass of wood, and _not the tallest of the

-group_, being struck by lightning, which passed down the trunk into

-the ground, rending the tree asunder. This shows that an object may be

-struck by lightning in a locality where there are numerous conducting

-points more elevated than itself; and at the same time proves that

-lightning cannot be diverted from its course by lofty isolated

-conductors, but that the protection of buildings from this species

-of meteor can only be effected by conductors stretching out in all

-directions.

-

-Professor Silliman states, that lightning-rods cannot be relied upon

-unless they reach the earth where it is permanently wet; and that the

-best security is afforded by carrying the rod, or some good metallic

-conductor duly connected with it, to the water in the well, or to some

-other water that never fails. The professor’s house, it seems, was

-struck; but his lightning-rods were not more than two or three inches

-in the ground, and were therefore virtually of no avail in protecting

-the building.

-

-

-ANCIENT LIGHTNING-CONDUCTOR.

-

-Humboldt informs us, that “the most important ancient notice of the

-relations between lightning and conducting metals is that of Ctesias,

-in his _Indica_, cap. iv. p. 190. He possessed two iron swords,

-presents from the king Artaxerxes Mnemon and from his mother Parasytis,

-which, when planted in the earth, averted clouds, hail, and _strokes of

-lightning_. He had himself seen the operation, for the king had twice

-made the experiment before his eyes.”--_Cosmos_, vol. ii.

-

-

-THE TEMPLE OF JERUSALEM PROTECTED FROM LIGHTNING.

-

-We do not learn, either from the Bible or Josephus, that the Temple

-at Jerusalem was ever struck by Lightning during an interval of more

-than a thousand years, from the time of Solomon to the year 70;

-although, from its situation, it was completely exposed to the violent

-thunderstorms of Palestine.

-

-By a fortuitous circumstance, the Temple was crowned with

-lightning-conductors similar to those which we now employ, and which

-we owe to Franklin’s discovery. The roof, constructed in what we call

-the Italian manner, and covered with boards of cedar, having a thick

-coating of gold, was garnished from end to end with long pointed and

-gilt iron or steel lances, which, Josephus says, were intended to

-prevent birds from roosting on the roof and soiling it. The walls

-were overlaid throughout with wood, thickly gilt. Lastly, there

-were in the courts of the Temple cisterns, into which the rain from

-the roof was conducted by _metallic pipes_. We have here both the

-lightning-rods and a means of conduction so abundant, that Lichtenberg

-is quite right in saying that many of the present apparatuses are far

-from offering in their construction so satisfactory a combination of

-circumstances.--_Abridged from Arago’s Meteorological Essays._

-

-

-HOW ST. PAUL’S CATHEDRAL IS PROTECTED FROM LIGHTNING.

-

-In March 1769, the Dean and Chapter of St. Paul’s addressed a letter

-to the Royal Society, requesting their opinion as to the best and most

-effectual method of fixing electrical conductors on the cathedral. A

-committee was formed for the purpose, and Benjamin Franklin was one of

-the members; their report was made, and the conductors were fixed as

-follows:

-

-  The seven iron scrolls supporting the ball and cross are connected

-  with other rods (used merely as conductors), which unite them

-  with several large bars, descending obliquely to the stone-work

-  of the lantern, and connected by an iron ring with four other

-  iron bars to the lead covering of the great cupola, a distance

-  of forty-eight feet; thence the communication is continued by

-  the rain-water pipes to the lead-covered roof, and thence by lead

-  water-pipes which pass into the earth; thus completing the entire

-  communication from the cross to the ground, partly through iron,

-  and partly through lead. On the clock-tower a bar of iron connects

-  the pine-apple at the top with the iron staircase, and thence with

-  the lead on the roof of the church. The bell-tower is similarly

-  protected. By these means the metal used in the building is made

-  available as conductors; the metal employed merely for that purpose

-  being exceedingly small in quantity.--_Curiosities of London._

-

-

-VARIOUS EFFECTS OF LIGHTNING.

-

-Dr. Hibbert tells us that upon the western coast of Scotland and

-Ireland, Lightning coöperates with the violence of the storm in

-shattering solid rocks, and heaping them in piles of enormous

-fragments, both on dry land and beneath the water.

-

-Euler informs us, in his _Letters to a German Princess_, that he

-corresponded with a Moravian priest named Divisch, who assured him

-that he had averted during a whole summer every thunderstorm which

-threatened his own habitation and the neighbourhood, by means of a

-machine constructed upon the principles of electricity; that the

-machinery sensibly attracted the clouds, and constrained them to

-descend quietly in a distillation, without any but a very distant

-thunderclap. Euler assures us that “the fact is undoubted, and

-confirmed by irresistible proof.”

-

-About the year 1811, in the village of Phillipsthal, in Eastern

-Prussia, an attempt was made to split an immense stone into a multitude

-of pieces by means of lightning. A bar of iron, in the form of a

-conductor, was previously fixed to the stone; and the experiment was

-attended with complete success; for during the very first thunderstorm

-the lightning burst the stone without displacing it.

-

-The celebrated Duhamel du Monceau says, that lightning, unaccompanied

-by thunder, wind, or rain, has the property of breaking oat-stalks. The

-farmers are acquainted with this effect, and say that the lightning

-breaks down the oats. This is a well-received opinion with the farmers

-in Devonshire.

-

-Lightning has in some cases the property of reducing solid bodies to

-ashes, or to pulverisation,--even the human body,--without there being

-any signs of heat. The effects of lightning on paralysis are very

-remarkable, in some cases curing, in others causing, that disease.

-

-The returning stroke of lightning is well known to be due to the

-restoration of the natural electric state, after it has been disturbed

-by induction.

-

-

-A THUNDERSTORM SEEN FROM A BALLOON.

-

-Mr. John West, the American aeronaut, in his observations made during

-his numerous ascents, describes a storm viewed from above the clouds

-to have the appearance of ebullition. The bulging upper surface of the

-cloud resembles a vast sea of boiling and upheaving snow; the noise

-of the falling rain is like that of a waterfall over a precipice; the

-thunder above the cloud is not loud, and the flashes of lightning

-appear like streaks of intensely white fire on a surface of white

-vapour. He thus describes a side view of a storm which he witnessed

-June 3, 1852, in his balloon excursion from Portsmouth, Ohio:

-

-  Although the sun was shining on me, the rain and small hail were

-  rattling on the balloon. A rainbow, or prismatically-coloured arch

-  or horse-shoe, was reflected against the sun; and as the point of

-  observation changed laterally and perpendicularly, the perspective

-  of this golden grotto changed its hues and forms. Above and behind

-  this arch was going on the most terrific thunder; but no zigzag

-  lightning was perceptible, only bright flashes, like explosions

-  of “Roman candles” in fireworks. Occasionally there was a zigzag

-  explosion in the cloud immediately below, the thunder sounding like

-  a _feu-de-joie_ of a rifle-corps. Then an orange-coloured wave of

-  light seemed to fall from the upper to the lower cloud; this was

-  “still-lightning.” Meanwhile intense electrical action was going

-  on _in the balloon_, such as expansion, tremulous tension, lifting

-  papers ten feet out of the car below the balloon and then dropping

-  them, &c. The close view of this Ohio storm was truly sublime; its

-  rushing noise almost appalling.

-

-Ascending from the earth with a balloon, in the rear of a storm, and

-mounted up a thousand feet above it, the balloon will soon override the

-storm, and may descend in advance of it. Mr. West has experienced this

-several times.

-

-

-REMARKABLE AERONAUTIC VOYAGE.

-

-Mr. Sadler, the celebrated aeronaut, ascended on one occasion in a

-balloon from Dublin, and was wafted across the Irish Channel; when,

-on his approach to the Welsh coast, the balloon descended nearly to

-the surface of the sea. By this time the sun was set, and the shades

-of evening began to close in. He threw out nearly all his ballast,

-and suddenly sprang upward to a great height; and by so doing brought

-his horizon to _dip_ below the sun, producing the whole phenomenon

-of a western sunrise. Subsequently descending in Wales, he of course

-witnessed a second sunset on the same evening.--_Sir John Herschel’s

-Outlines of Astronomy._

-

-

-

-

-Physical Geography of the Sea.[40]

-

-

-CLIMATES OF THE SEA.

-

-The fauna and flora of the Sea are as much the creatures of Climate,

-and are as dependent for their well-being upon temperature, as are the

-fauna and flora of the dry land. Were it not so, we should find the

-fish and the algæ, the marine insect and the coral, distributed equally

-and alike in all parts of the ocean; the polar whale would delight in

-the torrid zone; and the habitat of the pearl oyster would be also

-under the iceberg, or in frigid waters colder than the melting ice.

-

-

-THE CIRCULATION OF THE SEA.

-

-The coral islands, reefs, and beds with which the Pacific Ocean is

-studded and garnished, were built up of materials which a certain

-kind of insect quarried from the sea-water. The currents of the sea

-ministered to this little insect; they were its _hod-carriers_. When

-fresh supplies of solid matter were wanted for the coral rock upon

-which the foundations of the Polynesian Islands were laid, these

-hod-carriers brought them in unfailing streams of sea-water, loaded

-with food and building-materials for the coralline: the obedient

-currents thread the widest and the deepest sea. Now we know that

-its adaptations are suited to all the wants of every one of its

-inhabitants,--to the wants of the coral insect as well as those of the

-whale. Hence _we know_ that the sea has its system of circulation: for

-it transports materials for the coral rock from one part of the world

-to another; its currents receive them from rivers, and hand them over

-to the little mason for the structure of the most stupendous works of

-solid masonry that man has ever seen--the coral islands of the sea.

-

-

-TEMPERATURE OF THE SEA.

-

-Between the hottest hour of the day and the coldest hour of the night

-there is frequently a change of four degrees in the Temperature of the

-Sea. Taking one-fifth of the Atlantic Ocean for the scene of operation,

-and the difference of four degrees to extend only ten feet below

-the surface, the total and absolute change made in such a mass of

-sea-water, by altering its temperature two degrees, is equivalent to a

-change in its volume of 390,000,000 cubic feet.

-

-

-TRANSPARENCY OF THE OCEAN.

-

-Captain Glynn, U.S.N., has made some interesting observations, ranging

-over 200° of latitude, in different oceans, in very high latitudes,

-and near the equator. His apparatus was simple: a common white

-dinner-plate, slung so as to lie in the water horizontally, and sunk

-by an iron pot with a line. Numbering the fathoms at which the plate

-was visible below the surface, Captain Glynn saw it on two occasions,

-at the maximum, twenty-five fathoms (150 feet) deep; the water was

-extraordinarily clear, and to lie in the boat and look down was like

-looking down from the mast-head; and the objects were clearly defined

-to a great depth.

-

-

-THE BASIN OF THE ATLANTIC.

-

-In its entire length, the basin of this sea is a long trough,

-separating the Old World from the New, and extending probably from pole

-to pole.

-

-This ocean-furrow was scored into the solid crust of our planet by the

-Almighty hand, that there the waters which “he called seas” might be

-gathered together so as to “let the dry land appear,” and fit the earth

-for the habitation of man.

-

-From the top of Chimborazo to the bottom of the Atlantic, at the

-deepest place yet recognised by the plummet in the North Atlantic, the

-distance in a vertical line is nine miles.

-

-Could the waters of the Atlantic be drawn off, so as to expose to

-view this great sea-gash, which separates continents, and extends

-from the Arctic to the Antarctic, it would present a scene the most

-grand, rugged, and imposing. The very ribs of the solid earth, with

-the foundations of the sea, would be brought to light; and we should

-have presented to us at one view, in the empty cradle of the ocean,

-“a thousand fearful wrecks,” with that dreadful array of dead men’s

-skulls, great anchors, heaps of pearls and inestimable stones, which,

-in the dreamer’s eye, lie scattered on the bottom of the sea, making it

-hideous with sights of ugly death.

-

-

-GALES OF THE ATLANTIC.

-

-Lieutenant Maury has, in a series of charts of the North and South

-Atlantic, exhibited, by means of colours, the prevalence of Gales

-over the more stormy parts of the oceans for each month in the year.

-One colour shows the region in which there is a gale every six days;

-another colour every six to ten days; another every ten to fourteen

-days: and there is a separate chart for each month and each ocean.

-

-

-SOLITUDE AT SEA.

-

-Between Humboldt’s Current of Peru and the great equatorial flow, there

-is “a desolate region,” rarely visited by the whale, either sperm or

-right. Formerly this part of the ocean was seldom whitened by the sails

-of a ship, or enlivened by the presence of man. Neither the industrial

-pursuits of the sea nor the highways of commerce called him into it.

-Now and then a roving cruiser or an enterprising whalesman passed that

-way; but to all else it was an unfrequented part of the ocean, and so

-remained until the gold-fields of Australia and the guano islands of

-Peru made it a thoroughfare. All vessels bound from Australia to South

-America now pass through it; and in the journals of some of them it

-is described as a region almost void of the signs of life in both sea

-and air. In the South-Pacific Ocean especially, where there is such a

-wide expanse of water, sea-birds often exhibit a companionship with a

-vessel, and will follow and keep company with it through storm and calm

-for weeks together. Even the albatross and Cape pigeon, that delight

-in the stormy regions of Cape Horn and the inhospitable climates of

-the Antarctic regions, not unfrequently accompany vessels into the

-perpetual summer of the tropics. The sea-birds that join the ship as

-she clears Australia will, it is said, follow her to this region, and

-then disappear. Even the chirp of the stormy petrel ceases to be heard

-here, and the sea itself is said to be singularly barren of “moving

-creatures that have life.”

-

-

-BOTTLES AND CURRENTS AT SEA.

-

-Seafaring people often throw a bottle overboard, with a paper

-stating the time and place at which it is done. In the absence of

-other information as to Currents, that afforded by these mute little

-navigators is of great value. They leave no track behind them, it is

-true, and their routes cannot be ascertained; but knowing where they

-are cast, and seeing where they are found, some idea may be formed as

-to their course. Straight lines may at least be drawn, showing the

-shortest distance from the beginning to the end of their voyage, with

-the time elapsed. Admiral Beechey has prepared a chart, representing,

-in this way, the tracks of more than 100 bottles. From this it appears

-that the waters from every quarter of the Atlantic tend towards the

-Gulf of Mexico and its stream. Bottles cast into the sea midway between

-the Old and the New Worlds, near the coasts of Europe, Africa, and

-America at the extreme north or farthest south, have been found either

-in the West Indies, or the British Isles, or within the well-known

-range of Gulf-Stream waters.

-

-

-“THE HORSE LATITUDES”

-

-are the belts of calms and light airs which border the polar edge of

-the north-east trade-winds. They are so called from the circumstance

-that vessels formerly bound from New England to the West Indies, with a

-deck-load of horses, were often so delayed in this calm belt of Cancer,

-that, from the want of water for their animals, they were compelled to

-throw a portion of them overboard.

-

-

-“WHITE WATER” AND LUMINOUS ANIMALS AT SEA.

-

-Captain Kingman, of the American clipper-ship _Shooting Star_, in lat.

-8° 46′ S., long. 105° 30′ E., describes a patch of _white water_,

-about twenty-three miles in length, making the whole ocean appear like

-a plain covered with snow. He filled a 60-gallon tub with the water,

-and found it to contain small luminous particles seeming to be alive

-with worms and insects, resembling a grand display of rockets and

-serpents seen at a great distance in a dark night; some of the serpents

-appearing to be six inches in length, and very luminous. On being taken

-up, they emitted light until brought within a few feet of a lamp, when

-nothing was visible; but by aid of a sextant’s magnifier they could

-be plainly seen--a jelly-like substance, without colour. A specimen

-two inches long was visible to the naked eye; it was about the size

-of a large hair, and tapered at the ends. By bringing one end within

-about one-fourth of an inch of a lighted lamp, the flame was attracted

-towards it, and burned with a red light; the substance crisped in

-burning, something like hair, or appeared of a red heat before being

-consumed. In a glass of the water there were several small round

-substances (say 1/16th of an inch in diameter) which had the power of

-expanding and contracting; when expanded, the outer rim appeared like a

-circular saw, the teeth turned inward.

-

-The scene from the clipper’s deck was one of awful grandeur: the sea

-having turned to phosphorus, and the heavens being hung in blackness,

-and the stars going out, seemed to indicate that all nature was

-preparing for that last grand conflagration which we are taught to

-believe will annihilate this material world.

-

-

-INVENTION OF THE LOG.

-

-Long before the introduction of the Log, hour-glasses were used to

-tell the distance in sailing. Columbus, Juan de la Cosa, Sebastian

-Cabot, and Vasco de Gama, were not acquainted with the Log and its mode

-of application; and they estimated the ship’s speed merely by the eye,

-while they found the distance they had made by the running-down of the

-sand in the _ampotellas_, or hour-glasses. The Log for the measurement

-of the distance traversed is stated by writers on navigation not to

-have been invented until the end of the sixteenth or the beginning of

-the seventeenth century (see _Encyclopædia Britannica_, 7th edition,

-1842). The precise date is not known; but it is certain that Pigafetta,

-the companion of Magellan, speaks, in 1521, of the Log as a well-known

-means of finding the course passed over. Navarete places the use of the

-log-line in English ships in 1577.

-

-

-LIFE OF THE SEA-DEEPS.

-

-The ocean teems with life, we know. Of the four elements of the old

-philosophers,--fire, earth, air, and water,--perhaps the sea most of

-all abounds with living creatures. The space occupied on the surface

-of our planet by the different families of animals and their remains

-is inversely as the size of the individual; the smaller the animal,

-generally speaking, the greater the space occupied by his remains.

-Take the elephant and his remains, and a microscopic animal and his,

-and compare them; the contrast as to space occupied is as striking as

-that of the coral reef or island with the dimensions of the whale. The

-graveyard that would hold the corallines, is larger than the graveyard

-that would hold the elephants.

-

-

-DEPTHS OF OCEAN AND AIR UNKNOWN.

-

-At some few places under the tropics, no bottom has been found with

-soundings of 26,000 feet, or more than four miles; whilst in the air,

-if, according to Wollaston, we may assume that it has a limit from

-which waves of sound may be reverberated, the phenomenon of twilight

-would incline us to assume a height at least nine times as great. The

-aerial ocean rests partly on the solid earth, whose mountain-chains and

-elevated plateaus rise like green wooded shoals, and partly on the sea,

-whose surface forms a moving base, on which rest the lower, denser, and

-more saturated strata of air.--_Humboldt’s Cosmos_, vol. i.

-

-The old Alexandrian mathematicians, on the testimony of Plutarch,

-believed the depth of the sea to depend on the height of the mountains.

-Mr. W. Darling has propounded to the British Association the theory,

-that as the sea covers three times the area of the land, so it is

-reasonable to suppose that the depth of the ocean, and that for a

-large portion, is three times as great as the height of the highest

-mountain. Recent soundings show depths in the sea much greater than any

-elevations on the surface of the earth; for a line has been veered to

-the extent of seven miles.--_Dr. Scoresby._

-

-

-GREATEST ASCERTAINED DEPTH OF THE SEA.

-

-In the dynamical theory of the tides, the ratio of the effects of the

-sun and moon depends, not only on the masses, distances, and periodic

-times of the two luminaries, but also on the Depth of the Sea; and

-this, accordingly, may be computed when the other quantities are known.

-In this manner Professor Haughton has deduced, from the solar and lunar

-coefficients of the diurnal tide, a mean depth of 5·12 miles; a result

-which accords in a remarkable manner with that inferred from the ratio

-of the semi-diurnal co-efficients as obtained by Laplace from the

-Brest observations. Professor Hennessey states, that from what is now

-known regarding the depth of the ocean, the continents would appear as

-plateaus elevated above the oceanic depressions to an amount which,

-although small compared to the earth’s radius, would be considerable

-when compared to its outswelling at the equator and its flattening

-towards the poles; and the surface thus presented would be the true

-surface of the earth.

-

-The greatest depths at which the bottom of the sea has been reached

-with the plummet are in the North-Atlantic Ocean; and the places where

-it has been fathomed (by the United-States deep-sea sounding apparatus)

-do not show it to be deeper than 25,000 feet = 4 miles, 1293 yards, 1

-foot. The deepest place in this ocean is probably between the parallels

-of 35° and 40° north latitude, and immediately to the southward of the

-Grand Banks of Newfoundland.

-

-  It appears that, with one exception, the bottom of the

-  North-Atlantic Ocean, as far as examined, from the depth of about

-  sixty fathoms to that of more than two miles (2000 fathoms), is

-  literally nothing but a mass of microscopic shells. Not one of

-  the animalcules from these shells has been found living in the

-  surface-waters, nor in shallow water along the shore. Hence arises

-  the question, Do they live on the bottom, at the immense depths

-  where the shells are found; or are they borne by submarine currents

-  from their real habitat?

-

-

-RELATIVE LEVELS OF THE RED SEA AND MEDITERRANEAN.

-

-The French engineers, at the beginning of the present century, came

-to the conclusion that the Red Sea was about thirty feet above the

-Mediterranean: but the observations of Mr. Robert Stephenson, the

-English engineer, at Suez; of M. Negretti, the Austrian, at Tineh,

-near the ancient Pelusium; and the levellings of Messrs. Talabat,

-Bourdaloue, and their assistants between the two seas;--have proved

-that the low-water mark of ordinary tides at Suez and Tineh is very

-nearly on the same levels, the difference being that at Suez it is

-rather more than one inch lower.--_Leonard Horner_; _Proceedings of the

-Royal Society_, 1855.

-

-

-THE DEPTH OF THE MEDITERRANEAN.

-

-Soundings made in the Mediterranean suffice to indicate depths equal

-to the average height of the mountains girding round this great basin;

-and, if one particular experiment may be credited, reaching even to

-15,000 feet--an equivalent to the elevation of the highest Alps. This

-sounding was made about ninety miles east of Malta. Between Cyprus and

-Egypt, 6000 feet of line had been let down without reaching the bottom.

-Other deep soundings have been made in other places with similar

-results. In the lines of sea between Egypt and the Archipelago, it is

-stated that one sounding made by the _Tartarus_ between Alexandria

-and Rhodes reached bottom at the depth of 9900 feet; another, between

-Alexandria and Candia, gave a depth of 300 feet beyond this. These

-single soundings, indeed, whether of ocean or sea, are always open to

-the certainty that greater as well as lesser depths must exist, to

-which no line has ever been sunk; a case coming under that general law

-of probabilities so largely applicable in every part of physics. In the

-Mediterranean especially, which has so many aspects of a sunken basin,

-there may be abysses of depth here and there which no plummet is ever

-destined to reach.--_Edinburgh Review._

-

-

-COLOUR OF THE RED SEA.

-

-M. Ehrenberg, while navigating the Red Sea, observed that the red

-colour of its waters was owing to enormous quantities of a new animal,

-which has received the name of _oscillatoria rubescens_, and which

-seems to be the same with what Haller has described as a _purple

-conferva_ swimming in water; yet Dr. Bonar, in his work entitled _The

-Desert of Sinai_, records:

-

-  Blue I have called the sea; yet not strictly so, save in the far

-  distance. It is neither a _red_ nor a _blue_ sea, but emphatically

-  green,--yes, green, of the most brilliant kind I ever saw. This is

-  produced by the immense tracts of shallow water, with yellow sand

-  beneath, which always gives this green to the sea, even in the

-  absence of verdure on the shore or sea-weeds beneath. The _blue_ of

-  the sky and the _yellow_ of the sands meeting and intermingling in

-  the water, form the _green_ of the sea; the water being the medium

-  in which the mixing or fusing of the colours takes place.

-

-

-WHAT IS SEA-MILK?

-

-The phenomena with this name and that of “Squid” are occasioned by the

-presence of phosphorescent animalcules. They are especially produced

-in the intertropical seas, and they appear to be chiefly abundant

-in the Gulf of Guinea and in the Arabian Gulf. In the latter, the

-phenomenon was known to the ancients more than a century before the

-Christian era, as may be seen from a curious passage from the geography

-of Agatharcides: “Along this country (the coast of Arabia) the sea

-has a white aspect like a river: the cause of this phenomenon is a

-subject of astonishment to us.” M. Quatrefages has discovered that the

-_Noctilucæ_ which produce this phenomenon do not always give out clear

-and brilliant sparks, but that under certain circumstances this light

-is replaced by a steady clearness, which gives in these animalcules a

-white colour. The waters in which they have been observed do not change

-their place to any sensible degree.

-

-

-THE BOTTOM OF THE SEA A BURIAL-PLACE.

-

-Among the minute shells which have been fished up from the great

-telegraphic plateau at the bottom of the sea between Newfoundland and

-Ireland, the microscope has failed to detect a single particle of sand

-or gravel; and the inference is, that there, if any where, the waters

-of the sea are at rest. There is not motion enough there to abrade

-these very delicate organisms, nor current enough to sweep them about

-and mix them up with a grain of the finest sand, nor the smallest

-particle of gravel from the loose beds of _débris_ that here and there

-strew the bottom of the sea. The animalculæ probably do not live or die

-there. They would have had no light there; and, if they lived there,

-their frail textures would be subjected in their growth to a pressure

-upon them of a column of water 12,000 feet high, equal to the weight of

-400 atmospheres. They probably live and sport near the surface, where

-they can feel the genial influence of both light and heat, and are

-buried in the lichen caves below after death.

-

-It is now suggested, that henceforward we should view the surface of

-the sea as a nursery teeming with nascent organisms, and its depths as

-the cemetery for families of living creatures that outnumber the sands

-on the sea-shore for multitude.

-

-Where there is a nursery, hard by there will be found also a

-graveyard,--such is the condition of the animal world. But it never

-occurred to us before to consider the surface of the sea as one

-wide nursery, its every ripple as a cradle, and its bottom one vast

-burial-place.--_Lieut. Maury._

-

-

-WHY IS THE SEA SALT?

-

-It has been replied, In order to preserve it in a state of purity;

-which is, however, untenable, mainly from the fact that organic

-impurities in a vast body of moving water, whether fresh or salt,

-become rapidly lost, so as apparently to have called forth a special

-agency to arrest the total organised matter in its final oscillation

-between the organic and inorganic worlds. Thus countless hosts of

-microscopic creatures swarm in most waters, their principal function

-being, as Professor Owen surmises, to feed upon and thus restore to

-the living chain the almost unorganised matter of various zones. These

-creatures preying upon one another, and being preyed upon by others

-in their turn, the circulation of organic matter is kept up. If we

-do not adopt this view, we must at least look upon the Infusoria and

-Foraminifera as scavenger agents to prevent an undue accumulation

-of decaying matter; and thus the salt condition of the sea is not a

-necessity.

-

-Nor is the amount of saline matter in the sea sufficient to arrest

-decomposition. That the sea is salt to render it of greater density,

-and by lowering its freezing point to preserve it from congelation to

-within a shorter distance of the poles, though admissible, scarcely

-meets the entire solution of the question. The freezing point of

-sea-water, for instance, is only 3½° F. lower than that of fresh water;

-hence, with the present distribution of land and sea--and still less,

-probably, with that which obtained in former geological epochs--no very

-important effects would have resulted had the ocean been fresh instead

-of salt.

-

-Now Professor Chapman, of Toronto, suggests that the salt condition of

-the sea is mainly intended to regulate evaporation, and to prevent an

-undue excess of that phenomenon; saturated solutions evaporating more

-slowly than weak ones, and these latter more slowly again than pure

-water.

-

-Here, then, we have a self-adjusting phenomenon and admirable

-contrivance in the balance of forces. If from any temporary cause there

-be an unusual amount of saline matter in the sea, evaporation goes on

-the more and more slowly; and, on the other hand, if this proportion

-be reduced by the addition of fresh water in undue excess, the

-evaporating power is the more and more increased--thus aiding time, in

-either instance, to restore the balance. The perfect system of oceanic

-circulation may be ascribed, in a great degree at least, if not wholly,

-to the effect produced by the salts of the sea upon the mobility and

-circulation of its waters.

-

-Now this is an office which the sea performs in the economy of the

-universe by virtue of its saltness, and which it could not perform were

-its waters altogether fresh. And thus philosophers have a clue placed

-in their hands which will probably guide to one of the many hidden

-reasons that are embraced in the true answer to the question, “_Why is

-the sea salt?_”

-

-

-HOW TO ASCERTAIN THE SALTNESS OF THE SEA.

-

-Dry a towel in the sun, weigh it carefully, and note its weight. Then

-dip it into sea-water, wring it sufficiently to prevent its dripping,

-and weigh it again; the increase of the weight being that of the water

-imbibed by the cloth. It should then be thoroughly dried, and once more

-weighed; and the excess of this weight above the original weight of the

-cloth shows the quantity of the salt retained by it; then, by comparing

-the weight of this salt with that of the sea-water imbibed by the

-cloth, we shall find what proportion of salt was contained in the water.

-

-

-ALL THE SALT IN THE SEA.

-

-The amount of common Salt in all the oceans is estimated by Schafhäutl

-at 3,051,342 cubic geographical miles. This would be about five times

-more than the mass of the Alps, and only one-third less than that of

-the Himalaya. The sulphate of soda equals 633,644·36 cubic miles, or is

-equal to the mass of the Alps; the chloride of magnesium, 441,811·80

-cubic miles; the lime salts, 109,339·44 cubic miles. The above supposes

-the mean depth to be but 300 metres, as estimated by Humboldt.

-Admitting, with Laplace, that the mean depth is 1000 metres, which is

-more probable, the mass of marine salt will be more than double the

-mass of the Himalaya.--_Silliman’s Journal_, No. 16.

-

-Taking the average depth of the ocean at two miles, and its average

-saltness at 3½ per cent, it appears that there is salt enough in the

-sea to cover to the thickness of one mile an area of 7,000,000 of

-square miles. Admit a transfer of such a quantity of matter from an

-average of half a mile above to one mile below the sea-level, and

-astronomers will show by calculation that it would alter the length of

-the day.

-

-These 7,000,000 of cubic miles of crystal salt have not made the sea

-any fuller.

-

-

-PROPERTIES OF SEA-WATER.

-

-The solid constituents of sea-water amount to about 3½ per cent of

-its weight, or nearly half an ounce to the pound. Its saltness is

-caused as follows: Rivers which are constantly flowing into the

-ocean contain salts varying from 10 to 50, and even 100, grains per

-gallon. They are chiefly common salt, sulphate and carbonate of lime,

-magnesia,[41] soda, potash, and iron; and these are found to constitute

-the distinguishing characteristics of sea-water. The water which

-evaporates from the sea is nearly pure, containing but very minute

-traces of salts. Falling as rain upon the land, it washes the soil,

-percolates through the rocky layers, and becomes charged with saline

-substances, which are borne seaward by the returning currents. The

-ocean, therefore, is the great depository of every thing that water

-can dissolve and carry down from the surface of the continents; and

-as there is no channel for their escape, they consequently accumulate

-(_Youmans’ Chemistry_). They would constantly accumulate, as this very

-shrewd author remarks, were it not for the shells and insects of the

-sea and other agents.

-

-

-SCENERY AND LIFE OF THE ARCTIC REGIONS.

-

-The late Dr. Scoresby, from personal observations made in the course of

-twenty-one voyages to the Arctic Regions, thus describes these striking

-characteristics:

-

-  The coast scenes of Greenland are generally of an abrupt character,

-  the mountains frequently rising in triangular profile; so much

-  so, that it is sometimes not possible to effect their ascent. One

-  of the most notable characteristics of the Arctic lands is the

-  deception to which travellers are liable in regard to distances.

-  The occasion of this is the quantity of light reflected from

-  the snow, contrasted with the dark colour of the rocks. Several

-  persons of considerable experience have been deceived in this way,

-  imagining, for example, that they were close to the shore when in

-  fact they were more than twenty miles off. The trees of these lands

-  are not more than three inches above ground.

-

-  Many of the icebergs are five miles in extent, and some are to be

-  seen running along the shore measuring as much as thirteen miles.

-  Dr. Scoresby has seen a cliff of ice supported on those floating

-  masses 402 feet in height. There is no place in the world where

-  animal life is to be found in greater profusion than in Greenland,

-  Spitzbergen, Baffin’s Bay, and other portions of the Arctic

-  regions. This is to be accounted for by the abundance and richness

-  of the food supplied by the sea. The number of birds is especially

-  remarkable. On one occasion, no less than a million of little hawks

-  came in sight of Dr. Scoresby’s ship within a single hour.

-

-  The various phenomena of the Greenland sea are very interesting.

-  The different colours of the sea-water--olive or bottle-green,

-  reddish-brown, and mustard--have, by the aid of the microscope,

-  been found to be owing to animalculæ of these various colours:

-  in a single drop of mustard-coloured water have been counted

-  26,450 animals. Another remarkable characteristic of the Greenland

-  sea-water is its warm temperature--one, two, and three degrees

-  above the freezing-point even in the cold season. This Dr.

-  Scoresby accounts for by supposing the flow in that direction of

-  warm currents from the south. The polar fields of ice are to be

-  found from eight or nine to thirty or forty feet in thickness. By

-  fastening a hook twelve or twenty inches in these masses of ice, a

-  ship could ride out in safety the heaviest gales.

-

-

-ICEBERG OF THE POLAR SEAS.

-

-The ice of this berg, although opaque and vascular, is true glacier

-ice, having the fracture, lustre, and other external characters of

-a nearly homogeneous growth. The iceberg is true ice, and is always

-dreaded by ships. Indeed, though modified by climate, and especially by

-the alternation of day and night, the polar glacier must be regarded as

-strictly atmospheric in its increments, and not essentially differing

-from the glacier of the Alps. The general appearance of a berg may be

-compared to frosted silver; but when its fractures are very extensive,

-the exposed faces have a very brilliant lustre. Nothing can be more

-exquisite than a fresh, cleanly fractured berg surface: it reminds one

-of the recent cleavage of sulphate of strontian--a resemblance more

-striking from the slightly lazulitic tinge of each.--_U. S. Grinnel

-Expedition in Search of Sir J. Franklin._

-

-

-IMMENSITY OF POLAR ICE.

-

-The quantity of solid matter that is drifted out of the Polar Seas

-through one opening--Davis’s Straits--alone, and during a part of the

-year only, covers to the depth of seven feet an area of 300,000 square

-miles, and weighs not less than 18,000,000,000 tons. The quantity of

-water required to float and drive out this solid matter is probably

-many times greater than this. A quantity of water equal in weight to

-these two masses has to go in. The basin to receive these inflowing

-waters, _i. e._ the unexplored basin about the North Pole, includes an

-area of 1,500,000 square miles; and as the outflowing ice and water are

-at the surface, the return current must be submarine.

-

-These two currents, therefore, it may be perceived, keep in motion

-between the temperate and polar regions of the earth a volume of water,

-in comparison with which the mighty Mississippi in its greatest floods

-sinks down to a mere rill.--_Maury._

-

-

-OPEN SEA AT THE POLE.

-

-The following fact is striking: In 1662-3, Mr. Oldenburg, Secretary to

-the Royal Society, was ordered to register a paper entitled “Several

-Inquiries concerning Greenland, answered by Mr. Gray, who had visited

-those parts.” The nineteenth query was, “How near any one hath been

-known to approach the Pole. _Answer._ I once met upon the coast of

-Greenland a Hollander, that swore he had been but half a degree from

-the Pole, showing me his journal, which was also attested by his mate;

-where _they had seen no ice or land, but all water_.” Boyle mentions

-a similar account, which he received from an old Greenland master, on

-April 5, 1765.

-

-

-RIVER-WATER ON THE OCEAN.

-

-Captain Sabine found discoloured water, supposed to be that of the

-Amazon, 300 miles distant in the ocean from the embouchure of that

-river. It was about 126 feet deep. Its specific gravity was = 1·0204,

-and the specific gravity of the sea-water = 1·0262. This appears to

-be the greatest distance from land at which river-water has been

-detected on the surface of the ocean. It was estimated to be moving

-at the rate of three miles an hour, and had been turned aside by an

-ocean-current. “It is not a little curious to reflect,” says Sir Henry

-de la Beche, “that the agitation and resistance of its particles should

-be sufficient to keep finely comminuted solid matter mechanically

-suspended, so that it would not be disposed freely to part with it

-except at its junction with the sea-water over which it flows, and

-where, from friction, it is sufficiently retarded.”

-

-

-THE THAMES AND ITS SALT-WATER BED.

-

-The Thames below Woolwich, in place of flowing upon a solid bottom,

-really flows upon the liquid bottom formed by the water of the sea.

-At the flow of the tide, the fresh water is raised, as it were, in a

-single mass by the salt water which flows in, and which ascends the

-bed of the river, while the fresh water continues to flow towards the

-sea.--_Mr. Stevenson, in Jameson’s Journal._

-

-

-FRESH SPRINGS IN THE MIDDLE OF THE OCEAN.

-

-On the southern coast of the island of Cuba, at a few miles from land,

-Springs of Fresh Water gush from the bed of the Ocean, probably under

-the influence of hydrostatic pressure, and rise through the midst

-of the salt water. They issue forth with such force that boats are

-cautious in approaching this locality, which has an ill repute on

-account of the high cross sea thus caused. Trading vessels sometimes

-visit these springs to take in a supply of fresh water, which is thus

-obtained in the open sea. The greater the depth from which the water is

-taken, the fresher it is found to be.

-

-

-“THE BLACK WATERS.”

-

-In the upper portion of the basin of the Orinoco and its tributaries,

-Nature has several times repeated the enigmatical phenomenon of the

-so-called “Black Waters.” The Atabapo, whose banks are adorned with

-Carolinias and arborescent Melastomas, is a river of a coffee-brown

-colour. In the shade of the palm-groves this colour seems about to

-pass into ink-black. When placed in transparent vessels, the water

-appears of a golden yellow. The image of the Southern Constellation

-is reflected with wonderful clearness in these black streams. When

-their waters flow gently, they afford to the observer, when taking

-astronomical observations with reflecting instruments, a most excellent

-artificial horizon. These waters probably owe their peculiar colour to

-a solution of carburetted hydrogen, to the luxuriance of the tropical

-vegetation, and to the quantity of plants and herbs on the ground over

-which they flow.--_Humboldt’s Aspects of Nature_, vol. i.

-

-

-GREAT CATARACT IN INDIA.

-

-Where the river Shirhawti, between Bombay and Cape Comorin, falls into

-the Gulf of Arabia, it is about one-fourth of a mile in width, and in

-the rainy season some thirty feet in depth. This immense body of water

-rushes down a rocky slope 300 feet, at an angle of 45°, at the bottom

-of which it makes a perpendicular plunge of 850 feet into a black and

-dismal abyss, with a noise like the loudest thunder. The whole descent

-is therefore 1150 feet, or several times that of Niagara; but the

-volume of water in the latter is somewhat larger than in the former.

-

-

-CAUSE OF WAVES.

-

-The friction of the wind combines with the tide in agitating the

-surface of the ocean, and, according to the theory of undulations,

-each produces its effect independently of the other. Wind, however,

-not only raises waves, but causes a transfer of superficial water

-also. Attraction between the particles of air and water, as well

-as the pressure of the atmosphere, brings its lower stratum into

-adhesive contact with the surface of the sea. If the motion of the

-wind be parallel to the surface, there will still be friction, but the

-water will be smooth as a mirror; but if it be inclined, in however

-small a degree, a ripple will appear. The friction raises a minute

-wave, whose elevation protects the water beyond it from the wind,

-which consequently impinges on the surface at a small angle: thus

-each impulse, combining with the other, produces an undulation which

-continually advances.--_Mrs. Somerville’s Physical Geography._

-

-

-RATE AT WHICH WAVES TRAVEL.

-

-Professor Bache states, as one of the effects of an earthquake at

-Simoda, on the island of Niphon, in Japan, that the harbour was first

-emptied of water, and then came in an enormous wave, which again

-receded and left the harbour dry. This occurred several times. The

-United-States self-acting tide-gauge at San Francisco, which records

-the rise of the tide upon cylinders turned by clocks, showed that at

-San Francisco, 4800 miles from the scene of the earthquake, the first

-wave arrived twelve hours and sixteen minutes after it had receded from

-the harbour of Simoda. It had travelled across the broad bosom of the

-Pacific Ocean at the rate of six miles and a half a minute, and arrived

-on the shores of California: the first wave being seven-tenths of a

-foot in height, and lasting for about half an hour, followed by seven

-lesser waves, at intervals of half an hour each.

-

-The velocity with which a wave travels depends on the depth of the

-ocean. The latest calculations for the Pacific Ocean give a depth of

-from 14,000 to 18,000 fathoms. It is remarkable how the estimates of

-the ocean’s depth have grown less. Laplace assumed it at ten miles,

-Whewell at 3·5, while the above estimate brings it down to two miles.

-

-Mr. Findlay states, that the dynamic force exerted by Sea-Waves is

-greatest at the crest of the wave before it breaks; and its power in

-raising itself is measured by various facts. At Wasburg, in Norway,

-in 1820, it rose 400 feet; and on the coast of Cornwall, in 1843,

-300 feet. The author shows that waves have sometimes raised a column

-of water equivalent to a pressure of from three to five tons the

-square foot. He also proves that the velocity of the waves depends

-on their length, and that waves of from 300 to 400 feet in length

-from crest to crest travel from twenty to twenty-seven and a half

-miles an hour. Waves travel great distances, and are often raised by

-distant hurricanes, having been felt simultaneously at St. Helena

-and Ascension, though 600 miles apart; and it is probable that

-ground-swells often originate at the Cape of Good Hope, 3000 miles

-distant. Dr. Scoresby found the travelling rate of the Atlantic waves

-to be 32·67 English statute miles per hour.

-

-In the winter of 1856, a heavy ground-swell, brought on by five hours’

-gale, scoured away in fourteen hours 3,900,000 tons of pebbles from

-the coast near Dover; but in three days, without any shift of wind,

-upwards of 3,000,000 tons were thrown back again. These figures are to

-a certain extent conjectural; but the quantities have been derived from

-careful measurement of the profile of the beach.

-

-

-OCEAN-HIGHWAYS: HOW SEA-ROUTES HAVE BEEN SHORTENED.

-

-When one looks seaward from the shore, and sees a ship disappear

-in the horizon as she gains an offing on a voyage to India, or the

-Antipodes perhaps, the common idea is that she is bound over a

-trackless waste; and the chances of another ship sailing with the same

-destination the next day, or the next week, coming up and speaking

-with her on the “pathless ocean,” would to most minds seem slender

-indeed. Yet the truth is, the winds and the currents are now becoming

-so well understood, that the navigator, like the backwoodsman in the

-wilderness, is enabled literally to “blaze his way” across the ocean;

-not, indeed, upon trees, as in the wilderness, but upon the wings of

-the wind. The results of scientific inquiry have so taught him how to

-use these invisible couriers, that they, with the calm belts of the

-air, serve as sign-boards to indicate to him the turnings and forks and

-crossings by the way.

-

-  Let a ship sail from New York to California, and the next week let

-  a faster one follow; they will cross each other’s path many times,

-  and are almost sure to see each other by the way, as in the voyage

-  of two fine clipper-ships from New York to California. On the ninth

-  day after the _Archer_ had sailed, the _Flying Cloud_ put to sea.

-  Both ships were running against time, but without reference to

-  each other. The _Archer_, with wind and current charts in hand,

-  went blazing her way across the calms of Cancer, and along the

-  new route down through the north-east trades to the equator; the

-  _Cloud_ followed, crossing the equator upon the trail of Thomas of

-  the _Archer_. Off Cape Horn she came up with him, spoke him, and

-  handed him the latest New York dates. The _Flying Cloud_ finally

-  ranged ahead, made her adieus, and disappeared among the clouds

-  that lowered upon the western horizon, being destined to reach her

-  port a week or more in advance of her Cape Horn consort. Though

-  sighting no land from the time of their separation until they

-  gained the offing of San Francisco,--some six or eight thousand

-  miles off,--the tracks of the two vessels were so nearly the same,

-  that being projected upon the chart, they appear almost as one.

-

-  This is the great course of the ocean: it is 15,000 miles in

-  length. Some of the most glorious trials of speed and of prowess

-  that the world ever witnessed among ships that “walk the waters”

-  have taken place over it. Here the modern clipper-ship--the noblest

-  work that has ever come from the hands of man--has been sent,

-  guided by the lights of science, to contend with the elements, to

-  outstrip steam, and astonish the world.--_Maury._

-

-

-ERROR UPON ERROR.

-

-The great inducement to Mr. Babbage, some years since, to attempt

-the construction of a machine by which astronomical tables could be

-calculated and even printed by mechanical means, and with entire

-accuracy, was the errors in the requisite tables. Nineteen such

-errors, in point of fact, were discovered in an edition of Taylor’s

-_Logarithms_ printed in 1796; some of which might have led to the

-most dangerous results in calculating a ship’s place. These nineteen

-errors (of which one only was an error of the press) were pointed out

-in the _Nautical Almanac_ for 1832. In one of these _errata_, the seat

-of the error was stated to be in cosine of 14° 18′ 3″. Subsequent

-examination showed that there was an error of one second in this

-correction, and accordingly, in the _Nautical Almanac_ of the next

-year a new correction was necessary. But in making the new correction

-of one second, a new error was committed of ten degrees, making it

-still necessary, in some future edition of the _Nautical Almanac_,

-to insert an _erratum_ in an _erratum_ of the _errata_ in Taylor’s

-_Logarithms_.--_Edinburgh Review_, vol. 59.

-

-

-

-

-Phenomena of Heat.

-

-

-THE LENGTH OF THE DAY AND THE HEAT OF THE EARTH.

-

-As we may judge of the uniformity of temperature from the unaltered

-time of vibration of a pendulum, so we may also learn from the

-unaltered rotatory velocity of the earth the amount of stability in the

-mean temperature of our globe. This is the result of one of the most

-brilliant applications of the knowledge we had long possessed of the

-movement of the heavens to the thermic condition of our planet. The

-rotatory velocity of the earth depends on its volume; and since, by the

-gradual cooling of the mass by radiation, the axis of rotation would

-become shorter, the rotatory velocity would necessarily increase, and

-the length of the day diminish with a decrease of the temperature. From

-the comparison of the secular inequalities in the motions of the moon

-with the eclipses observed in former ages, it follows that, since the

-time of Hipparchus,--that is, for full 2000 years,--the length of the

-day has certainly not diminished by the hundredth part of a second. The

-decrease of the mean heat of the globe during a period of 2000 years

-has not therefore, taking the extremest limits, diminished as much as

-1/306th of a degree of Fahrenheit.[42]--_Humboldt’s Cosmos_, vol. i.

-

-

-NICE MEASUREMENT OF HEAT.

-

-A delicate thermometer, placed on the ground, will be affected by the

-passage of a single cloud across a clear sky; and if a succession of

-clouds pass over, with intervals of clear sky between them, such an

-instrument has been observed to fluctuate accordingly, rising with each

-passing mass of vapour, and falling again when the radiation becomes

-unrestrained.

-

-

-EXPENDITURE OF HEAT BY THE SUN.

-

-Sir John Herschel estimates the total Expenditure of Heat by the Sun in

-a given time, by supposing a cylinder of ice 45 miles in diameter to be

-continually darted into the sun _with the velocity of light_, and that

-the water produced by its fusion were continually carried off: the heat

-now given off constantly by radiation would then be wholly expended in

-its liquefaction, on the one hand, so as to leave no radiant surplus;

-while, on the other, the actual temperature at its surface would

-undergo no diminution.

-

-The great mystery, however, is to conceive how so enormous a

-conflagration (if such it be) can be kept up. Every discovery in

-chemical science here leaves us completely at a loss, or rather

-seems to remove further the prospect of probable explanation. If

-conjecture might be hazarded, we should look rather to the known

-possibility of an indefinite generation of heat by friction, or to

-its excitement by the electric discharge, than to any combustion of

-ponderable fuel, whether solid or gaseous, for the origin of the solar

-radiation.--_Outlines._[43]

-

-

-DISTINCTIONS OF HEAT.

-

-Among the curious laws of modern science are those which regulate the

-transmission of radiant heat through transparent bodies. The heat of

-our fires is intercepted and detained by screens of glass, and, being

-so detained, warms them; while solar heat passes freely through and

-produces no such effect. “The more recent researches of Delaroche,”

-says Sir John Herschel, “however, have shown that this detention is

-complete only when the temperature of the source of heat is low; but

-that as the temperature gets higher a portion of the heat radiated

-acquires a power of penetrating glass, and that the quantity which does

-so bears continually a larger and larger proportion to the whole, as

-the heat of the radiant body is more intense. This discovery is very

-important, as it establishes a community of nature between solar and

-terrestrial heat; while at the same time it leads us to regard the

-actual temperature of the sun as far exceeding that of any earthly

-flame.”

-

-

-LATENT HEAT.

-

-This extraordinary principle exists in all bodies, and may be pressed

-out of them. The blacksmith hammers a nail until it becomes red hot,

-and from it he lights the match with which he kindles the fire of his

-forge. The iron has by this process become more dense, and percussion

-will not again produce incandescence until the bar has been exposed in

-fire to a red heat, when it absorbs heat, the particles are restored to

-their former state, and we can again by hammering develop both heat and

-light.--_R. Hunt, F.R.S._

-

-

-HEAT AND EVAPORATION.

-

-In a communication made to the French Academy, M. Daubrée calculates

-that the Evaporation of the Water on the surface of the globe employs a

-quantity of heat about equal to one-third of what is received from the

-sun; or, in other words, equal to the melting of a bed of ice nearly

-thirty-five feet in thickness if spread over the globe.

-

-

-HEAT AND MECHANICAL POWER.

-

-It has been found that Heat and Mechanical Power are mutually

-convertible; and that the relation between them is definite, 772

-foot-pounds of motive power being equivalent to a unit of heat, that

-is, to the amount of heat requisite to raise a pound of water through

-one degree of Fahrenheit.

-

-

-HEAT OF MINES.

-

-One cause of the great Heat of many of our deep Mines, which appears to

-have been entirely lost sight of, is the chemical action going on upon

-large masses of pyritic matter in their vicinity. The heat, which is so

-oppressive in the United Mines in Cornwall that the miners work nearly

-naked, and bathe in water at 80° to cool themselves, is without doubt

-due to the decomposition of immense quantities of the sulphurets of

-iron and copper known to be in this condition at a short distance from

-these mineral works.--_R. Hunt, F.R.S._

-

-

-VIBRATION OF HEATED METALS.

-

-Mr. Arthur Trevelyan discovered accidentally that a bar of iron, when

-heated and placed with one end on a solid block of lead, in cooling

-vibrates considerably, and produces sounds similar to those of an

-Æolian harp. The same effect is produced by bars of copper, zinc,

-brass, and bell-metal, when heated and placed on blocks of lead, tin,

-or pewter. The bars were four inches long, one inch and a half wide,

-and three-eighths of an inch thick.

-

-The conditions essential to these experiments are, That two different

-metals must be employed--the one soft and possessed of moderate

-conducting powers, viz. lead or tin, the other hard; and it matters not

-whether soft metal be employed for the bar or block, provided the soft

-metal be cold and the hard metal heated.

-

-That the surface of the block shall be uneven, for when rendered quite

-smooth the vibration does not take place; but the bar cannot be too

-smooth.

-

-That no matter be interposed, else it will prevent vibration, with

-the exception of a burnish of gold leaf, the thickness of which cannot

-amount to the two-hundred-thousandth part of an inch.--_Transactions of

-the Royal Society of Edinburgh._

-

-

-EXPANSION OF SPIRITS.

-

-Spirits expand and become lighter by means of heat in a greater

-proportion than water, wherefore they are heaviest in winter. A cubic

-inch of brandy has been found by many experiments to weigh ten grains

-more in winter than in summer, the difference being between four drams

-thirty-two grains and four drams forty-two grains. Liquor-merchants

-take advantage of this circumstance, and make their purchases in winter

-rather than in summer, because they get in reality rather a larger

-quantity in the same bulk, buying by measure.--_Notes in Various

-Sciences._

-

-

-HEAT PASSING THROUGH GLASS.

-

-The following experiment is by Mr. Fox Talbot: Heat a poker bright-red

-hot, and having opened a window, apply the poker quickly very near

-to the outside of a pane, and the hand to the inside; a strong heat

-will be felt at the instant, which will cease as soon as the poker

-is withdrawn, and may be again renewed and made to cease as quickly

-as before. Now it is well known, that if a piece of glass is so much

-warmed as to convey the impression of heat to the hand, it will retain

-some part of that heat for a minute or more; but in this experiment the

-heat will vanish in a moment: it will not, therefore, be the heated

-pane of glass that we shall feel, but heat which has come through the

-glass in a free or radiant state.

-

-

-HEAT FROM GAS-LIGHTING.

-

-In the winter of 1835, Mr. W. H. White ascertained the temperature in

-the City to be 3° higher than three miles south of London Bridge; and

-_after the gas had been lighted in the City_ four or five hours the

-temperature increased full 3°, thus making 6° difference in the three

-miles.

-

-

-HEAT BY FRICTION.

-

-Friction as a source of Heat is well known: we rub our hands to

-warm them, and we grease the axles of carriage-wheels to prevent

-their setting fire to the wood. Count Rumford has established the

-extraordinary fact, that an unlimited supply of heat may be derived

-from friction by the same materials: he made great quantities of water

-boil by causing a blunt borer to rub against a mass of metal immersed

-in the water. Savages light their fires by rubbing two pieces of wood:

-the _modus operandi_, as practised by the Kaffirs of South Africa, is

-thus described by Captain Drayton:

-

-  Two dry sticks, one being of hard and the other of soft wood, were

-  the materials used. The soft stick was laid on the ground, and

-  held firmly down by one Kaffir, whilst another employed himself

-  in scooping out a little hole in the centre of it with the point

-  of his assagy: into this little hollow the end of the hard wood

-  was placed, and held vertically. These two men sat face to face,

-  one taking the vertical stick between the palms of his hands, and

-  making it twist about very quickly, while the other Kaffir held the

-  lower stick firmly in its place; the friction caused by the end of

-  one piece of wood revolving upon the other soon made the two pieces

-  smoke. When the Kaffir who twisted became tired, the respective

-  duties were exchanged. These operations having continued about a

-  couple of minutes, sparks began to appear, and when they became

-  numerous, were gathered into some dry grass, which was then swung

-  round at arm’s length until a blaze was established; and a roaring

-  fire was gladdening the hearts of the Kaffirs with the anticipation

-  of a glorious feast in about ten minutes from the time that the

-  operation was first commenced.

-

-

-HEAT BY FRICTION FROM ICE.

-

-When Sir Humphry Davy was studying medicine at Penzance, one of his

-constant associates was Mr. Tom Harvey, a druggist in the above town.

-They constantly experimented together; and one severe winter’s day,

-after a discussion on the nature of heat, the young philosophers were

-induced to go to Larigan river, where Davy succeeded in developing heat

-by _rubbing two pieces of ice together_ so as to melt each other;[44]

-an experiment which he repeated with much _éclat_ many years after,

-in the zenith of his celebrity, at the Royal Institution. The pieces

-of ice for this experiment are fastened to the ends of two sticks,

-and rubbed together in air below the temperature of 32°: this Davy

-readily accomplished on the day of severe cold at the Larigan river;

-but when the experiment was repeated at the Royal Institution, it was

-in the vacuum of an air-pump, when the temperature of the apparatus and

-of the surrounding air was below 32°. It was remarked, that when the

-surface of the rubbing pieces was rough, only half as much heat was

-evolved as when it was smooth. When the pressure of the rubbing piece

-was increased four times, the proportion of heat evolved was increased

-sevenfold.

-

-

-WARMING WITH ICE.

-

-In common language, any thing is understood to be cooled or warmed when

-the temperature thereof is made higher or lower, whatever may have been

-the temperature when the change was commenced. Thus it is said that

-melted iron is _cooled_ down to a sub-red heat, or mercury is cooled

-from the freezing point to zero, or far below. By the same rule, solid

-mercury, say 50° below zero, may, in any climate or temperature of the

-atmosphere, be immediately warmed and melted by being imbedded in a

-cake of ice.--_Scientific American._

-

-

-REPULSION BY HEAT.

-

-If water is poured upon an iron sieve, the wires of which are made

-red-hot, it will not run through; but on cooling, it will pass through

-rapidly. M. Boutigny, pursuing this curious inquiry, has proved

-that the moisture upon the skin is sufficient to protect it from

-disorganisation if the arm is plunged into baths of melted metal.

-The resistance of the surfaces is so great that little elevation of

-temperature is experienced. Professor Plücker has stated, that by

-washing the arm with ether previously to plunging it into melted metal,

-the sensation produced while in the molten mass is that of freezing

-coldness.--_R. Hunt, F.R.S._

-

-

-PROTECTION FROM INTENSE HEAT.

-

-The singular power which the body possesses of resisting great heats,

-and of breathing air of high temperatures, has at various times excited

-popular wonder. In the last century some curious experiments were

-made on this subject. Sir Joseph Banks, Dr. Solander, and Sir Charles

-Blagden, entered a room in which the air had a temperature of 198°

-Fahr., and remained ten minutes. Subsequently they entered the room

-separately, when Dr. Solander found the heat 210°, and Sir Joseph

-211°, whilst their bodies preserved their natural degree of heat.

-Whenever they breathed upon a thermometer, it sank several degrees;

-every inspiration gave coolness to their nostrils, and their breath

-cooled their fingers when it reached them. Sir Charles Blagden entered

-an apartment when the heat was 1° or 2° above 260°, and remained eight

-minutes, mostly on the coolest spot, where the heat was above 240°.

-Though very hot, Sir Charles felt no pain: during seven minutes his

-breathing was good; but he then felt an oppression in his lungs, and

-his pulse was 144, double its ordinary quickness. To prove the heat of

-the room, eggs and a beefsteak were placed upon a tin frame near the

-thermometer, when in twenty minutes the eggs were roasted hard, and in

-forty-seven minutes the steak was dressed dry; and when the air was put

-in motion by a pair of bellows upon another steak, part of it was well

-done in thirteen minutes. It is remarkable, that in these experiments

-the same person who experienced no inconvenience from air heated to

-211°, could just bear rectified spirits of wine at 130°, cooling oil at

-129°, cooling water at 123°, and cooling quicksilver at 117°.

-

-Sir Francis Chantrey, the sculptor, however, exposed himself to a

-temperature still higher than any yet mentioned, as described by Sir

-David Brewster:

-

-  The furnace which he employs for drying his moulds is about

-  fourteen feet long, twelve feet high, and twelve feet broad. When

-  it is raised to its highest temperature, with the doors closed,

-  the thermometer stands at 350°, and the iron floor is red-hot. The

-  workmen often enter it at a temperature of 340°, walking over the

-  iron floor with wooden clogs, which are of course charred on the

-  surface. On one occasion, Mr. Chantrey, accompanied by five or

-  six of his friends, entered the furnace; and after remaining two

-  minutes they brought out a thermometer which stood at 320°. Some

-  of the party experienced sharp pains in the tips of their ears

-  and in the septum of the nose, while others felt a pain in their

-  eyes.--_Natural Magic_, 1833.

-

-In some cases the clothing worn by the experimenters conducts away

-the heat. Thus, in 1828, a Spaniard entered a heated oven, at the New

-Tivoli, near Paris; he sang a song while a fowl was roasted by his

-side, he then ate the fowl and drank a bottle of wine, and on coming

-out his pulse beat 176°, and the thermometer was at 110° Reaumur. He

-then stretched himself upon a plank in the oven surrounded by lighted

-candles, when the mouth of the oven was closed; he remained there five

-minutes, and on being taken out, all the candles were extinguished and

-melted, and the Spaniard’s pulse beat 200°. Now much of the surprise

-ceases when it is added that he wore wide woollen pantaloons, a loose

-mantle of wool, and a great quilted cap; the several materials of this

-clothing being bad conductors of heat.

-

-In 1829 M. Chabert, the “Fire-King,” exhibited similar feats at the

-Argyll Rooms in Regent Street. He first swallowed forty grains of

-phosphorus, then two spoonfuls of oil at 330°, and next held his head

-over the fumes of sulphuric acid. He had previously provided himself

-with an antidote for the poison of the phosphorus. Dressed in a loose

-woollen coat, he then entered a heated oven, and in five minutes cooked

-two steaks; he then came out of the oven, when the thermometer stood at

-380°. Upon another occasion, at White Conduit House, some of his feats

-were detected.

-

-The scientific secret is as follows: Muscular tissue is an extremely

-bad conductor; and to this in a great measure the constancy of the

-temperature of the human body in various zones is to be attributed. To

-this fact also Sir Charles Blagden and Chantrey owed their safety in

-exposing their bodies to a high temperature; from the almost impervious

-character of the tissues of the body, the irritation produced was

-confined to the surface.

-

-

-

-

-Magnetism and Electricity.

-

-

-MAGNETIC HYPOTHESES.

-

-As an instance of the obstacles which erroneous hypotheses throw

-in the way of scientific discovery, Professor Faraday adduces the

-unsuccessful attempts that had been made in England to educe Magnetism

-from Electricity until Oersted showed the simple way. Faraday relates,

-that when he came to the Royal Institution as an assistant in the

-laboratory, he saw Davy, Wollaston, and Young trying, by every way that

-suggested itself to them, to produce magnetic effects from an electric

-current; but having their minds diverted from the true course by their

-existing hypotheses, it did not occur to them to try the effect of

-holding a wire through which an electric current was passing over a

-suspended magnetic needle. Had they done so, as Oersted afterwards did,

-the immediate deflection of the needle would have proved the magnetic

-property of an electric current. Faraday has shown that the magnetism

-of a steel bar is caused by the accumulated action of all the particles

-of which it is composed: this he proves by first magnetising a small

-steel bar, and then breaking it successively into smaller and smaller

-pieces, each one of which possesses a separate pole; and the same

-operation may be continued until the particles become so small as not

-to be distinguishable without a microscope.

-

-We quote the above from a late Number of the _Philosophical Magazine_,

-wherein also we find the following noble tribute to the genius and

-public and private worth of Faraday:

-

-  The public never can know and appreciate the national value of such

-  a man as Faraday. He does not work to please the public, nor to win

-  its guineas; and the said public, if asked its opinion as to the

-  practical value of his researches, can see no possible practical

-  issue there. The public does not know that we need prophets

-  more than mechanics in science,--inspired men, who, by patient

-  self-denial and the exercise of the high intellectual gifts of the

-  Creator, bring us intelligence of His doings in Nature. To them

-  their pursuits are good in themselves. Their chief reward is the

-  delight of being admitted into communion with Nature, the pleasure

-  of tracing out and proclaiming her laws, wholly forgetful whether

-  those laws will ever augment our banker’s account or improve our

-  knowledge of cookery. _Such men, though not honoured by the title

-  of “practical,” are they which make practical men possible._

-  They bring us the tamed forces of Nature, and leave it to others

-  to contrive the machinery to which they may be yoked. If we are

-  rightly informed, it was Faradaic electricity which shot the glad

-  tidings of the fall of Sebastopol from Balaklava to Varna. Had

-  this man converted his talent to commercial purposes, as so many

-  do, we should not like to set a limit to his professional income.

-  The quality of his services cannot be expressed by pounds; but

-  that brave body, which for forty years has been the instrument

-  of that great soul, is a fit object for a nation’s care, as the

-  achievements of the man are, or will one day be, the object of a

-  nation’s pride and gratitude.

-

-

-THE CHINESE AND THE MAGNETIC NEEDLE.

-

-More than a thousand years before our era, a people living in the

-extremest eastern portions of Asia had magnetic carriages, on which the

-movable arm of the figure of a man continually pointed to the south,

-as a guide by which to find the way across the boundless grass-plains

-of Tartary; nay, even in the third century of our era, therefore at

-least 700 years before the use of the mariner’s compass in European

-seas, Chinese vessels navigated the Indian Ocean under the direction of

-Magnetic Needles pointing to the south.

-

-  Now the Western nations, the Greeks and the Romans, knew that

-  magnetism could be communicated to iron, and _that that metal_

-  would retain it for a length of time. The great discovery of

-  the terrestrial directive force depended, therefore, alone

-  on this--that no one in the West had happened to observe an

-  elongated fragment of magnetic iron-stone, or a magnetic iron rod,

-  floating by the aid of a piece of wood in water, or suspended

-  in the air by a thread, in such a position as to admit of free

-  motion.--_Humboldt’s Cosmos_, vol. i.

-

-

-KIRCHER’S “MAGNETISM.”

-

-More than two centuries since, Athanasius Kircher published his strange

-book on Magnetism, in which he anticipated the supposed virtue of

-magnetic traction in the curative art, and advocated the magnetism

-of the sun and moon, of the divining-rod, and showed his firm belief

-in animal magnetism. “In speaking of the vegetable world,” says Mr.

-Hunt, “and the remarkable processes by which the leaf, the flower,

-and the fruit are produced, this sage brings forward the fact of the

-diamagnetic (repelled by the magnet) character of the plant which was

-in 1852 rediscovered; and he refers the motions of the sunflower, the

-closing of the convolvulus, and the directions of the spiral formed

-by the twining plants, to this particular influence.”[45] Nor were

-Kircher’s anticipations random guesses, but the result of deductions

-from experiment and observation; and the universality of magnetism is

-now almost recognised by philosophers.

-

-

-MINUTE MEASUREMENT OF TIME.

-

-By observing the magnet in the highly-convenient and delicate manner

-introduced by Gauss and Weber, which consists in attaching a mirror

-to the magnet and determining the constant factor necessary to convert

-the differences of oscillation into differences of time, Professor

-Helmholtz has been able, with comparatively simple apparatus, to make

-accurate determinations up to the 1/10000th part of a second.

-

-

-POWER OF A MAGNET.

-

-The Power of a Magnet is estimated by the weight its poles are able

-to carry. Each pole singly is able to support a smaller weight than

-when they both act together by means of a keeper, for which reason

-horse-shoe magnets are superior to bar magnets of similar dimensions

-and character. It has further been ascertained that small magnets have

-a much greater relative force than large ones.

-

-When magnetism is excited in a piece of steel in the ordinary mode, by

-friction with a magnet, it would seem that its inductive power is able

-to overcome the coercive power of the steel only to a certain depth

-below the surface; hence we see why small pieces of steel, especially

-if not very hard, are able to carry greater relative weights than large

-magnets. Sir Isaac Newton wore in a ring a magnet weighing only 3

-grains, which would lift 760 grains, _i. e._ 250 times its own weight.

-

-Bar-magnets are seldom found capable of carrying more than their own

-weight; but horse-shoe magnets of similar steel will bear considerably

-more. Small ones of from half an ounce to 1 ounce in weight will carry

-from 30 to 40 times their own weight; while such as weigh from 1 to 2

-lbs. will rarely carry more than from 10 to 15 times their weight. The

-writer found a 1 lb. horse-shoe magnet that he impregnated by means of

-the feeder able to bear 26½ times its own weight; and Fischer, having

-adopted the like mode of magnetising the steel, which he also carefully

-heated, has made magnets of from 1 to 3 lbs. weight that would carry 30

-times, and others of from 4 to 6 lbs. weight that would carry 20 times,

-their own weight.--_Professor Peschel._

-

-

-HOW ARTIFICIAL MAGNETS ARE MADE.

-

-In 1750, Mr. Canton, F.R.S., “one of the most successful experimenters

-in the golden age of electricity,”[46] communicated to the Royal

-Society his “Method of making Artificial Magnets without the use

-of natural ones.” This he effected by using a poker and tongs to

-communicate magnetism to steel bars. He derived his first hint from

-observing them one evening, as he was sitting by the fire, to be nearly

-in the same direction with the earth as the dipping needle. He thence

-concluded that they must, from their position and the frequent blows

-they receive, have acquired some magnetic virtue, which on trial he

-found to be the case; and therefore he employed them to impregnate his

-bars, instead of having recourse to the natural loadstone. Upon the

-reading of the above paper, Canton exhibited to the Royal Society his

-experiments, for which the Copley Medal was awarded to him in 1751.

-

-Canton had, as early as 1747, turned his attention, with complete

-success, to the production of powerful artificial magnets, principally

-in consequence of the expense of procuring those made by Dr. Gowan

-Knight, who kept his process secret. Canton for several years abstained

-from communicating his method even to his most intimate friends,

-lest it might be injurious to Dr. Knight, who procured considerable

-pecuniary advantages by touching needles for the mariner’s compass.

-

-At length Dr. Knight’s method of making artificial magnets was

-communicated to the world by Mr. Wilson, in a paper published in the

-69th volume of the _Philosophical Transactions_. He provided himself

-with a large quantity of clean iron-filings, which he put into a

-capacious tub about half full of clear water; he then agitated the

-tub to and fro for several hours, until the filings were reduced by

-attrition to an almost impalpable powder. This powder was then dried,

-and formed into paste by admixture with linseed-oil. The paste was then

-moulded into convenient shapes, which were exposed to a moderate heat

-until they had attained a sufficient degree of hardness.

-

-  After allowing them to remain for some time in this state, Dr.

-  Knight gave them their magnetic virtue in any direction he pleased,

-  by placing them between the extreme ends of his large magazine of

-  artificial magnets for a second or more, as he saw occasion. By

-  this method the virtue they acquired was such, that when any one of

-  these pieces was held between two of his best ten-guinea bars, with

-  its poles purposely inverted, it immediately of itself turned about

-  to recover its natural direction, which the force of those very

-  powerful bars was not sufficient to counteract.

-

-Dr. Knight’s powerful battery of magnets above mentioned is in the

-possession of the Royal Society, having been presented by Dr. John

-Fothergill in 1776.

-

-

-POWER OF THE SUN’S RAYS IN INCREASING THE STRENGTH OF MAGNETS.

-

-Professor Barlocci found that an armed natural loadstone, which would

-carry 1½ Roman pounds, had its power nearly _doubled_ by twenty-four

-hours’ exposure to the strong light of the sun. M. Zantedeschi found

-that an artificial horse-shoe loadstone, which carried 13½ oz., carried

-3½ more by three days’ exposure, and at last arrived to 31 oz. by

-continuing it in the sun’s light. He found that while the strength

-increased in oxidated magnets, it diminished in those which were not

-oxidated, the diminution becoming insensible when the loadstone was

-highly polished. He now concentrated the solar rays upon the loadstone

-by means of a lens; and he found that, both in oxidated and polished

-magnets, they _acquire_ strength when their _north_ pole is exposed

-to the sun’s rays, and _lose_ strength when the _south_ pole is

-exposed.--_Sir David Brewster._

-

-

-COLOUR OF A BODY AND ITS MAGNETIC PROPERTIES.

-

-Solar rays bleach dead vegetable matter with rapidity, while in living

-parts of plants their action is frequently to strengthen the colour.

-Their power is perhaps best seen on the sides of peaches, apples, &c.,

-which, exposed to a midsummer’s sun, become highly coloured. In the

-open winter of 1850, Mr. Adie, of Liverpool, found in a wallflower

-plant proof of a like effect: in the dark months there was a slow

-succession of one or two flowers, of uniform pale yellow hue; in March

-streaks of a darker colour appeared on the flowers, and continued to

-slowly increase till in April they were variegated brown and yellow,

-of rich strong colours. On the supposition that these changes are

-referable to magnetic properties, may hereafter be explained Mrs.

-Somerville’s experiments on steel needles exposed to the sun’s rays

-under envelopes of silk of various colours; the magnetisation of steel

-needles has failed in the coloured rays of the spectrum, but Mr. Adie

-considers that under dyed silk the effect will hinge on the chemical

-change wrought in the silk and its dye by the solar rays.

-

-

-THE ONION AND MAGNETISM.

-

-A popular notion has long been current, more especially on the shores

-of the Mediterranean, that if a magnetic rod be rubbed with an onion,

-or brought in contact with the emanations of the plant, the directive

-force will be diminished, while a compass thus treated will mislead the

-steersman. It is difficult to conceive what could have given rise to so

-singular a popular error.[47]--_Humboldt’s Cosmos_, vol. v.

-

-

-DECLINATION OF THE NEEDLE--THE EARTH A MAGNET.

-

-The Inclination or Dip of the Needle was first recorded by Robert

-Norman, in a scarce book published in 1576 entitled _The New

-Attractive; containing a short Discourse of the Magnet or Loadstone,

-&c._

-

-Columbus has not only the merit of being the first to discover _a

-line without magnetic variation_, but also of having first excited a

-taste for the study of terrestrial magnetism in Europe, by means of

-his observations on the progressive increase of western declination in

-receding from that line.

-

-The first chart showing the variation of the compass,[48] or the

-declination of the needle, based on the idea of employing curves drawn

-through points of equal declination, is due to Halley, who is justly

-entitled the father and founder of terrestrial magnetism. And it is

-curious to find that in No. 195 of the _Philosophical Transactions_,

-in 1683, Halley had previously expressed his belief that he has put it

-past doubt that the globe of the earth is one great magnet, having four

-magnetical poles or points of attraction, near each pole of the equator

-two; and that in those parts of the world which lie near adjacent to

-any one of those magnetical poles, the needle is chiefly governed

-thereby, the nearest pole being always predominant over the more remote.

-

-“To Halley” (says Sir John Herschel) “we owe the first appreciation

-of the real complexity of the subject of magnetism. It is wonderful

-indeed, and a striking proof of the penetration and sagacity of this

-extraordinary man, that with his means of information he should

-have been able to draw such conclusions, and to take so large and

-comprehensive a view of the subject as he appears to have done.”

-

-And, in our time, “the earth is a great magnet,” says Faraday: “its

-power, according to Gauss, being equal to that which would be conferred

-if every cubic yard of it contained six one-pound magnets; the sum of

-the force is therefore equal to 8,464,000,000,000,000,000,000 such

-magnets.”

-

-

-THE AURORA BOREALIS.

-

-Halley, upon his return from his voyage to verify his theory of the

-variation of the compass, in 1700, hazarded the conjecture that the

-Aurora Borealis is a magnetic phenomenon. And Faraday’s brilliant

-discovery of the evolution of light by magnetism has raised Halley’s

-hypothesis, enounced in 1714, to the rank of an experimental certainty.

-

-

-EFFECT OF LIGHT ON THE MAGNET.

-

-In 1854, Sir John Ross stated to the British Association, in proof of

-the effect of every description of light on the magnet, that during

-his last voyage in the _Felix_, when frozen in about one hundred miles

-north of the magnetic pole, he concentrated the rays of the full moon

-on the magnetic needle, when he found it was five degrees attracted by

-it.

-

-

-MAGNETO-ELECTRICITY.

-

-In 1820, the Copley Medal was adjudicated to M. Oersted of Copenhagen,

-“when,” says Dr. Whewell, “the philosopher announced that the

-conducting-wire of a voltaic circuit acts upon a magnetic needle; and

-thus recalled into activity that endeavour to connect magnetism with

-electricity which, though apparently on many accounts so hopeful, had

-hitherto been attended with no success. Oersted found that the needle

-has a tendency to place itself at _right angles_ to the wire; a kind of

-action altogether different from any which had been suspected.”

-

-

-ELECTRO-MAGNETS OF THE HORSE-SHOE FORM

-

-were discovered by Sturgeon in 1825. Of two Magnets made by a process

-devised by M. Elias, and manufactured by M. Logemeur at Haerlem, one,

-a single horse-shoe magnet weighing about 1 lb., lifts 28½ lbs.; the

-other, a triple horse-shoe magnet of about 10 lbs. weight, is capable

-of lifting about 150 lbs. Similar magnets are made by the same person

-capable of supporting 5 cwt. In the process of making them, a helix of

-copper and a galvanic battery are used. The smaller magnet has twice

-the power expressed by Haecker’s formula for the best artificial steel

-magnet.

-

-Subsequently Henry and Ten Eyk, in America, constructed some

-electro-magnets on a large scale. One horse-shoe magnet made by them,

-weighing 60 lbs., would support more than 2000 lbs.

-

-In September 1858, there were constructed for the Atlantic-telegraph

-cable at Valentia two permanent magnets, from which the electric

-induction is obtained: each is composed of 30 horse-shoe magnets, 2½

-feet long and from 4 to 5 inches broad; the induction coils attached to

-these each contain six miles of wire, and a shock from them, if passed

-through the human body, would be sufficient to destroy life.

-

-

-ROTATION-MAGNETISM.

-

-The unexpected discovery of Rotation-Magnetism by Arago, in 1825,

-has shown practically that every kind of matter is susceptible of

-magnetism; and the recent investigations of Faraday on diamagnetic

-substances have, under special conditions of meridian or equatorial

-direction, and of solid, fluid, or gaseous inactive conditions of the

-bodies, confirmed this important result.

-

-

-INFLUENCE OF PENDULUMS ON EACH OTHER.

-

-About a century since it became known, that when two clocks are in

-action upon the same shelf, they will disturb each other: that the

-pendulum of the one will stop that of the other; and that the pendulum

-that was stopped will after a while resume its vibrations, and in its

-turn stop that of the other clock. When two clocks are placed near

-one another in cases very slightly fixed, or when they stand on the

-boards of a floor, they will affect a little each other’s pendulum.

-Mr. Ellicote observed that two clocks resting against the same rail,

-which agreed to a second for several days, varied one minute thirty-six

-seconds in twenty-four hours when separated. The slower, having a

-longer pendulum, set the other in motion in 16-1/3 minutes, and stopped

-itself in 36-2/3 minutes.

-

-

-WEIGHT OF THE EARTH ASCERTAINED BY THE PENDULUM.

-

-By a series of comparisons with Pendulums placed at the surface and

-the interior of the Earth, the Astronomer-Royal has ascertained the

-variation of gravity in descending to the bottom of a deep mine, as

-the Harton coal-pit, near South Shields. By calculations from these

-experiments, he has found the mean density of the earth to be 6·566,

-the specific gravity of water being represented by unity. In other

-words, it has been ascertained by these experiments that if the earth’s

-mass possessed every where its average density, it would weigh, bulk

-for bulk, 6·566 times as much as water. It is curious to note the

-different values of the earth’s mean density which have been obtained

-by different methods. The Schehallien experiment indicated a mean

-density equal to about 4½; the Cavendish apparatus, repeated by Baily

-and Reich, about 5½; and Professor Airy’s pendulum experiment furnishes

-a value amounting to about 6½.

-

-The immediate result of the computations of the Astronomer-Royal is:

-supposing a clock adjusted to go true time at the top of the mine, it

-would gain 2¼ seconds per day at the bottom. Or it may be stated thus:

-that gravity is greater at the bottom of a mine than at the top by

-1/19190th part.--_Letter to James Mather, Esq., South Shields._ See

-also _Professor Airy’s Lecture_, 1854.

-

-

-ORIGIN OF TERRESTRIAL MAGNETISM.

-

-The earliest view of Terrestrial Magnetism supposed the existence

-of a magnet at the earth’s centre. As this does not accord with the

-observations on declination, inclination, and intensity, Tobias

-Meyer gave this fictitious magnet an eccentric position, placing it

-one-seventh part of the earth’s radius from the centre. Hansteen

-imagined that there were two such magnets, different in position

-and intensity. Ampère set aside these unsatisfactory hypotheses by

-the view, derived from his discovery, that the earth itself is an

-electro-magnet, magnetised by an electric current circulating about

-it from east to west perpendicularly to the plane of the magnetic

-meridian, to which the same currents give direction as well as

-magnetise the ores of iron: the currents being thermo-electric

-currents, excited by the action of the sun’s heat successively on the

-different parts of the earth’s surface as it revolves towards the east.

-

-William Gilbert,[49] who wrote an able work on magnetic and electric

-forces in the year 1600, regarded terrestrial magnetism and electricity

-as two emanations of a single fundamental source pervading all matter,

-and he therefore treated of both at once. According to Gilbert’s idea,

-the earth itself is a magnet; whilst he considered that the inflections

-of the lines of equal declination and inclination depend upon the

-distribution of mass, the configuration of continents, or the form and

-extent of the deep intervening oceanic basins.

-

-Till within the last eighty years, it appears to have been the received

-opinion that the intensity of terrestrial magnetism was the same at

-all parts of the earth’s surface. In the instructions drawn up by

-the French Academy for the expedition under La Pérouse, the first

-intimation is given of a contrary opinion. It is recommended that the

-time of vibration of a dipping-needle should be observed at stations

-widely remote, as a test of the equality or difference of the magnetic

-intensity; suggesting also that such observations should particularly

-be made at those parts of the earth where the dip was greatest and

-where it was least. The experiments, whatever their results may have

-been, which, in compliance with this recommendation, were made in the

-expedition of La Pérouse, perished in its general catastrophe; but the

-instructions survived.

-

-In 1811, Hansteen took up the subject, and in 1819 published his

-celebrated work, clearly demonstrating the fluctuations which this

-element has undergone during the last two centuries; confirming in

-great detail the position of Halley, that “the whole magnetic system is

-in motion, that the moving force is very great as extending its effects

-from pole to pole, and that its motion is not _per saltum_, but a

-gradual and regular motion.”

-

-

-THE NORTH AND SOUTH MAGNETIC POLES.

-

-The knowledge of the geographical position of both Magnetic Poles is

-due to the scientific energy of the same navigator, Sir James Ross.

-His observations of the Northern Magnetic Pole were made during the

-second expedition of his uncle, Sir John Ross (1829-1833); and of

-the Southern during the Antarctic expedition under his own command

-(1839-1843). The Northern Magnetic Pole, in 70° 5′ lat., 96° 43′ W.

-long., is 5° of latitude farther from the ordinary pole of the earth

-than the Southern Magnetic Pole, 75° 35′ lat., 154° 10′ E. long.;

-whilst it is also situated farther west from Greenwich than the

-Northern Magnetic Pole. The latter belongs to the great island of

-Boothia Felix, which is situated very near the American continent,

-and is a portion of the district which Captain Parry had previously

-named North Somerset. It is not far distant from the western coast of

-Boothia Felix, near the promontory of Adelaide, which extends into King

-William’s Sound and Victoria Strait.

-

-The Southern Magnetic Pole has been directly reached in the same manner

-as the Northern Pole. On 17th February 1841, the _Erebus_ penetrated

-as far as 76° 12′ S. lat., and 164° E. long. As the inclination was

-here only 88° 40′, it was assumed that the Southern Magnetic Pole

-was about 160 nautical miles distant. Many accurate observations of

-declination, determining the intersection of the magnetic meridian,

-render it very probable that the South Magnetic Pole is situated in the

-interior of the great Antarctic region of South Victoria Land, west

-of the Prince Albert mountains, which approach the South Pole and are

-connected with the active volcano of Erebus, which is 12,400 feet in

-height.--_Humboldt’s Cosmos_, vol. v.

-

-

-MAGNETIC STORMS.

-

-The mysterious course of the magnetic needle is equally affected by

-time and space, by the sun’s course, and by changes of place on the

-earth’s surface. Between the tropics the hour of the day may be known

-by the direction of the needle as well as by the oscillations of the

-barometer. It is affected instantly, but transiently, by the northern

-light.

-

-When the uniform horary motion of the needle is disturbed by a magnetic

-storm, the perturbation manifests itself _simultaneously_, in the

-strictest sense of the word, over hundreds and thousands of miles of

-sea and land, or propagates itself by degrees in short intervals every

-where over the earth’s surface.

-

-Among numerous examples of perturbations occurring simultaneously and

-extending over wide portions of the earth’s surface, one of the most

-remarkable is that of September 25th, 1841, which was observed at

-Toronto in Canada, at the Cape of Good Hope, at Prague, and partially

-in Van Diemen’s Land. Sabine adds, “The English Sunday, on which it is

-deemed sinful, after midnight on Saturday, to register an observation,

-and to follow out the great phenomena of creation in their perfect

-development, interrupted the observation in Van Diemen’s Land, where,

-in consequence of the difference of the longitude, the magnetic storm

-fell on Sunday.”

-

-  It is but justice to add, that to the direct instrumentality of the

-  British Association we are indebted for this system of observation,

-  which would not have been possible without some such machinery

-  for concerted action. It being known that the magnetic needle is

-  subject to oscillations, the nature, the periods, and the laws

-  of which were unascertained, under the direction of a committee

-  of the Association _magnetic observatories_ were established in

-  various places for investigating these strange disturbances. As

-  might have been anticipated, regularly recurring perturbations were

-  noted, depending on the hour of the day and the season of the year.

-  Magnetic storms were observed to sweep simultaneously over the

-  whole face of the earth, and these too have now been ascertained to

-  follow certain periodic laws.

-

-  But the most startling result of the combined magnetic observations

-  is the discovery of marked perturbations recurring at intervals of

-  ten years; a period which seemed to have no analogy to any thing

-  in the universe, but which M. Schwabe has found to correspond

-  with the variation of the spots on the sun, both attaining their

-  maximum and minimum developments at the same time. Here, for the

-  present, the discovery stops; but that which is now an unexplained

-  coincidence may hereafter supply the key to the nature and source

-  of Terrestrial Magnetism: or, as Dr. Lloyd observes, this system of

-  magnetic observation has gone beyond our globe, and opened a new

-  range for inquiry, by showing us that this wondrous agent has power

-  in other parts of the solar system.

-

-

-FAMILIAR GALVANIC EFFECTS.

-

-By means of the galvanic agency a variety of surprising effects have

-been produced. Gunpowder, cotton, and other inflammable substances have

-been set on fire; charcoal has been made to burn with a brilliant white

-flame; water has been decomposed into its elementary parts; metals

-have been melted and set on fire; fragments of diamond, charcoal, and

-plumbago have been dispersed as if evaporated; platina, the hardest

-and the heaviest of the metals, has been melted as readily as wax in

-the flame of a candle; the sapphire, quartz, magnesia, lime, and the

-firmest compounds in nature, have been fused. Its effects on the animal

-system are no less surprising.

-

-The agency of galvanism explains why porter has a different and more

-pleasant taste when drunk out of a pewter-pot than out of glass or

-earthenware; why works of metal which are soldered together soon

-tarnish in the place where the metals are joined; and why the copper

-sheathing of ships, when fastened with iron nails, is soon corroded

-about the place of contact. In all these cases a galvanic circle is

-formed which produces the effects.

-

-

-THE SIAMESE TWINS GALVANISED.

-

-It will be recollected that the Siamese twins, brought to England in

-the year 1829, were united by a jointed cartilaginous band. A silver

-tea spoon being placed on the tongue of one of the twins and a disc of

-zinc on the tongue of the other, the moment the two metals were brought

-into contact both the boys exclaimed, “Sour, sour;” thus proving that

-the galvanic influence passed from the one to the other through the

-connecting band.

-

-

-MINUTE AND VAST BATTERIES.

-

-Dr. Wollaston made a simple apparatus out of a silver thimble, with its

-top cut off. It was then partially flattened, and a small plate of zinc

-being introduced into it, the apparatus was immersed in a weak solution

-of sulphuric acid. With this minute battery, Dr. Wollaston was able to

-fuse a wire of platinum 1/3000th of an inch in diameter--a degree of

-tenuity to which no one had ever succeeded in drawing it.

-

-Upon the same principle (that of introducing a plate of zinc between

-two plates of other metals) Mr. Children constructed his immense

-battery, the zinc plates of which measured six feet by two feet eight

-inches; each plate of zinc being placed between two of copper, and each

-triad of plates being enclosed in a separate cell. With this powerful

-apparatus a wire of platinum, 1/10th of an inch in diameter and upwards

-of five feet long, was raised to a red heat, visible even in the broad

-glare of daylight.

-

-The great battery at the Royal Institution, with which Sir Humphry Davy

-discovered the composition of the fixed alkalies, was of immense power.

-It consisted of 200 separate parts, each composed of ten double plates,

-and each plate containing thirty-two square inches; the number of

-double plates being 2000, and the whole surface 128,000 square inches.

-

-Mr. Highton, C.E., has made a battery which exposes a surface of only

-1/100th part of an inch: it consists of but one cell; it is less than

-1/10000th part of a cubic inch, and yet it produces electricity more

-than enough to overcome all the resistance in the inventor’s brother’s

-patent Gold-leaf Telegraph, and works the same powerfully. It is, in

-short, a battery which, although _it will go through the eye of a

-needle_, will yet work a telegraph well. Mr. Highton had previously

-constructed a battery in size less than 1/40th of a cubic inch: this

-battery, he found, would for a month together ring a telegraph-bell ten

-miles off.

-

-

-ELECTRIC INCANDESCENCE OF CHARCOAL POINTS.

-

-The most splendid phenomenon of this kind is the combustion of charcoal

-points. Pointed pieces of the residuum obtained from gas retorts will

-answer best, or Bunsen’s composition may be used for this purpose. Put

-two such charcoal points in immediate contact with the wires of your

-battery; bring the points together, and they will begin to burn with

-a dazzling white light. The charcoal points of the large apparatus

-belonging to the Royal Institution became incandescent at a distance of

-1/30th of an inch; when the distance was gradually increased till they

-were four inches asunder, they continued to burn with great intensity,

-and a permanent stream of light played between them. Professor Bunsen

-obtained a similar flame from a battery of four pairs of plates,

-its carbon surface containing 29 feet. The heat of this flame is so

-intense, that stout platinum wire, sapphire, quartz, talc, and lime

-are reduced by it to the liquid form. It is worthy of remark, that no

-combustion, properly so called, takes place in the charcoal itself,

-which sustains only an extremely minute loss in its weight and becomes

-rather denser at the points. The phenomenon is attended with a still

-more vivid brightness if the charcoal points are placed in a vacuum,

-or in any of those gases which are not supporters of combustion.

-Instead of two charcoal points, one only need be used if the following

-arrangement is adopted: lay the piece of charcoal on some quicksilver

-that is connected with one pole of the battery, and complete the

-circuit from the other pole by means of a strip of platinum. When

-Professor Peschel used a piece of well-burnt coke in the manner just

-described, he obtained a light which was almost intolerable to the eyes.

-

-

-VOLTAIC ELECTRICITY.

-

-On January 31, 1793, Volta announced to the Royal Society his discovery

-of the development of electricity in metallic bodies. Galvani had given

-the name of Animal Electricity to the power which caused spontaneous

-convulsions in the limbs of frogs when the divided nerves were

-connected by a metallic wire. Volta, however, saw the true cause of the

-phenomena described by Galvani. Observing that the effects were far

-greater when the connecting medium consisted of two different kinds

-of metal, he inferred that the principle of excitation existed in the

-metals, and not in the nerves of the animal; and he assumed that the

-exciting fluid was ordinary electricity, produced by the contact of the

-two metals; the convulsions of the frog consequently arose from the

-electricity thus developed passing along its nerves and muscles.

-

-In 1800 Volta invented what is now called the Voltaic Pile, or compound

-Galvanic circle.

-

-  The term Animal Electricity (says Dr. Whewell) has been superseded

-  by others, of which _Galvanism_ is the most familiar; but I think

-  that Volta’s office in this discovery is of a much higher and more

-  philosophical kind than that of Galvani; and it would on this

-  account be more fitting to employ the term _Voltaic Electricity_,

-  which, indeed, is very commonly used, especially by our most

-  recent and comprehensive writers. The _Voltaic pile_ was a more

-  important step in the history of electricity than the Leyden jar

-  had been--_Hist. Ind. Sciences_, vol. iii.

-

-  No one who wishes to judge impartially of the scientific history

-  of these times and of its leaders, will consider Galvani and

-  Volta as equals, or deny the vast superiority of the latter over

-  all his opponents or fellow-workers, more especially over those

-  of the Bologna school. We shall scarcely again find in one man

-  gifts so rich and so calculated for research as were combined

-  in Volta. He possessed that “incomprehensible talent,” as Dove

-  has called it, for separating the essential from the immaterial

-  in complicated phenomena; that boldness of invention which must

-  precede experiment, controlled by the most strict and cautious

-  mode of manipulation; that unremitting attention which allows no

-  circumstance to pass unnoticed; lastly, with so much acuteness,

-  so much simplicity, so much grandeur of conception, combined with

-  such depth of thought, he had a hand which was the hand of a

-  workman.--_Jameson’s Journal_, No. 106.

-

-

-THE VOLTAIC BATTERY AND THE GYMNOTUS.

-

-“We boast of our Voltaic Batteries,” says Mr. Smee. “I should hardly

-be believed if I were to say that I did not feel pride in having

-constructed my own, especially when I consider the extensive operations

-which it has conducted. But when I compare my battery with the battery

-which nature has given to the electrical eel and the torpedo, how

-insignificant are human operations compared with those of the Architect

-of living beings! The stupendous electric eel in the Polytechnic

-Institution, when he seeks to kill his prey, encloses him in a circle;

-then, by volition, causes the voltaic force to be produced, and the

-hapless creature is instantly killed. It would probably require ten

-thousand of my artificial batteries to effect the same object, as

-the creature is killed _instanter_ on receiving the shock. As much,

-however, as my battery is inferior to that of the electric fish, so

-is man superior to the same animal. Man is endowed with a power of

-mind competent to appreciate the force of matter, and is thus enabled

-to make the battery. The eel can but use the specific apparatus which

-nature has bestowed upon it.”

-

-Some observations upon the electric current around the gymnotus, and

-notes of experiments with this and other electric fish, will be found

-in _Things not generally Known_, p. 199.

-

-

-VOLTAIC CURRENTS IN MINES.

-

-Many years ago, Mr. R. W. Fox, from theory entertaining a belief

-that a connection existed between voltaic action in the interior of

-the earth and the arrangement of metalliferous veins, and also the

-progressive increase of temperature in the strata as we descend from

-the surface, endeavoured to verify the same from experiment in the mine

-of Huel Jewel, in Cornwall. His apparatus consisted of small plates

-of sheet-copper, which were fixed in contact with a plate in the veins

-with copper nails, or else wedged closely against them with wooden

-props stretched across the galleries. Between two of these plates,

-at different stations, a communication was made by means of a copper

-wire 1/20th of an inch in diameter, which included a galvanometer

-in its circuit. In some instances 300 fathoms of copper wire were

-employed. It was then found that the intensity of the voltaic current

-was generally greater in proportion to the greater abundance of copper

-ore in the veins, and in some degree to the depth of the stations.

-Hence Mr. Fox’s discovery promised to be of practical utility to the

-miner in discovering the relative quantity of ore in the veins, and the

-directions in which it most abounds.

-

-The result of extended experiments, mostly made by Mr. Robert Hunt,

-has not, however, confirmed Mr. Fox’s views. It has been found that

-the voltaic currents detected in the lodes are due to the chemical

-decomposition going on there; and the more completely this process

-of decomposition is established, the more powerful are the voltaic

-currents. Meanwhile these have nothing whatever to do with the increase

-of temperature with depth. Recent observations, made in the deep mines

-of Cornwall under the direction of Mr. Fox, do not appear consistent

-with the law of thermic increase as formerly established, the shallow

-mines giving a higher ratio of increase than the deeper ones.

-

-

-GERMS OF ELECTRIC KNOWLEDGE.

-

-Two centuries and a half ago, Gilbert recognised that the property of

-attracting light substances when rubbed, be their nature what it may,

-is not peculiar to amber, which is a condensed earthy juice cast up by

-the waves of the sea, and in which flying insects, ants, and worms lie

-entombed as in eternal sepulchres. The force of attraction (Gilbert

-continues) belongs to a whole class of very different substances, as

-glass, sulphur, sealing-wax, and all resinous substances--rock crystal

-and all precious stones, alum and rock-salt. Gilbert measured the

-strength of the excited electricity by means of a small needle--not

-made of iron--which moved freely on a pivot, and perfectly similar to

-the apparatus used by Haüy and Brewster in testing the electricity

-excited in minerals by heat and friction. “Friction,” says Gilbert

-further, “is productive of a stronger effect in dry than in humid air;

-and rubbing with silk cloths is most advantageous.”

-

-Otto von Guerike, the inventor of the air-pump, was the first who

-observed any thing more than mere phenomena of attraction. In his

-experiments with a rubbed piece of sulphur he recognised the

-phenomena of repulsion, which subsequently led to the establishment

-of the laws of the sphere of action and of the distribution of

-electricity. _He heard the first sound, and saw the first light, in

-artificially-produced electricity._ In an experiment instituted by

-Newton in 1675, the first traces of an electric charge in a rubbed

-plate of glass were seen.

-

-

-TEMPERATURE AND ELECTRICITY.

-

-Professor Tyndall has shown that all variations of temperature, in

-metals at least, excite electricity. When the wires of a galvanometer

-are brought in contact with the two ends of a heated poker, the prompt

-deflection of the galvanometer-needle indicates that a current of

-electricity has been sent through the instrument. Even the two ends of

-a spoon, one of which has been dipped in hot water, serve to develop an

-electric current; and in cutting a hot beefsteak with a steel knife and

-a silver fork there is an excitement of electricity. The mere heat of

-the finger is sufficient to cause the deflection of the galvanometer;

-and when ice is applied to the part that has been previously warmed,

-the galvanometer-needle is deflected in the contrary direction. A small

-instrument invented by Melloni is so extremely sensitive of the action

-of heat, that electricity is excited when the hand is held six inches

-from it.

-

-

-VAST ARRANGEMENT OF ELECTRICITY.

-

-Professor Faraday has shown that the Electricity which decomposes,

-and that which is evolved in the decomposition of, a certain quantity

-of matter, are alike. What an enormous quantity of electricity,

-therefore, is required for the decomposition of a single grain of

-water! It must be in quantity sufficient to sustain a platinum wire

-1/104th of an inch in thickness red-hot in contact with the air

-for three minutes and three-quarters. It would appear that 800,000

-charges of a Leyden battery, charged by thirty turns of a very large

-and powerful plate-machine in full action, are necessary to supply

-electricity sufficient to decompose a single grain of water, or to

-equal the quantity of electricity which is naturally associated with

-the elements of that grain of water, endowing them with their mutual

-chemical affinity. Now the above quantity of electricity, if passed at

-once through the head of a rat or a cat, would kill it as by a flash of

-lightning. The quantity is, indeed, equal to that which is developed

-from a charged thunder-cloud.

-

-

-DECOMPOSITION OF WATER BY ELECTRICITY.

-

-Professor Andrews, by an ingenious arrangement, is enabled to show that

-water is decomposed by the common machine; and by using an electrical

-kite, he was able, in fine weather, to produce decomposition, although

-so slowly that only 1/700000th of a grain of water was decomposed per

-hour. Faraday has proved that the decomposition of one single grain of

-water produces more electricity than is contained in the most powerful

-flash of lightning.

-

-

-ELECTRICITY IN BREWING.

-

-Mr. Black, a practical writer upon Brewing, has found that by the

-practice of imbedding the fermentation-vats in the earth, and

-connecting them by means of metallic pipes, an electrical current

-passes through the beer and causes it to turn sour. As a preventive,

-he proposed to place the vats upon wooden blocks, or on any other

-non-conductors, so that they may be insulated. It has likewise been

-ascertained that several brewers who had brewed excellent ale on the

-south side of the street, on removing to the north have failed to

-produce good ale.

-

-

-ELECTRIC PAPER.

-

-Professor Schonbein has prepared paper, as transparent as glass and

-impermeable to water, which develops a very energetic electric force.

-By placing some sheets on each other, and simply rubbing them once or

-twice with the hand, it becomes difficult to separate them. If this

-experiment is performed in the dark, a great number of distinct flashes

-may be perceived between the separated surfaces. The disc of the

-electrophorus, placed on a sheet that has been rubbed, produces sparks

-of some inches in length. A thin and very dry sheet of paper, placed

-against the wall, will adhere strongly to it for several hours if the

-hand be passed only once over it. If the same sheet be passed between

-the thumb and fore-finger in the dark, a luminous band will be visible.

-Hence with this paper may be made powerful and cheap electrical

-machines.

-

-

-DURATION OF THE ELECTRIC SPARK.

-

-By means of Professor Wheatstone’s apparatus, the Duration

-of the Electric Spark has been ascertained not to exceed the

-twenty-five-thousandth part of a second. A cannon-ball, if illumined

-in its flight by a flash of lightning, would, in consequence of the

-momentary duration of the light, appear to be stationary, and even the

-wings of an insect, that move ten thousand times in a second, would

-seem at rest.

-

-

-VELOCITY OF ELECTRIC LIGHT.

-

-On comparing the velocities of solar, stellar, and terrestrial light,

-which are all equally refracted in the prism, with the velocity of the

-light of frictional electricity, we are disposed, in accordance with

-Wheatstone’s ingeniously-conducted experiments, to regard the lowest

-ratio in which the latter excels the former as 3:2. According to the

-lowest results of Wheatstone’s apparatus, electric light traverses

-288,000 miles in a second. If we reckon 189,938 miles for stellar

-light, according to Struve, we obtain the difference of 95,776 miles as

-the greater velocity of electricity in one second.

-

-From the experiment described in Wheatstone’s paper (_Philosophical

-Transactions_ for 1834), it would appear that the human eye is capable

-of perceiving phenomena of light whose duration is limited to the

-millionth part of a second.

-

-In Professor Airy’s experiments with the electric telegraph to

-determine the difference of longitude between Greenwich and Brussels,

-the time spent by the electric current in passing from one observatory

-to the other (270 miles) was found to be 0·109″ or rather more than

-_the ninth part of a second_; and this determination rests on 2616

-observations: a speed which would “girdle the globe” in ten seconds.

-

-

-IDENTITY OF ELECTRIC AND MAGNETIC ATTRACTION.

-

-This vague presentiment of the ancients has been verified in our own

-times. “When electrum (amber),” says Pliny, “is animated by friction

-and heat, it will attract bark and dry leaves precisely as the

-loadstone attracts iron.” The same words may be found in the literature

-of an Asiatic nation, and occur in a eulogium on the loadstone by the

-Chinese physicist Knopho, in the fourth century: “The magnet attracts

-iron as amber does the smallest grain of mustard-seed. It is like

-a breath of wind, which mysteriously penetrates through both, and

-communicates itself with the rapidity of an arrow.”

-

-  Humboldt observed with astonishment on the woody banks of the

-  Orinoco, in the sports of the natives, that the excitement of

-  electricity by friction was known to these savage races. Children

-  may be seen to rub the dry, flat, and shining seeds or husks of a

-  trailing plant until they are able to attract threads of cotton

-  and pieces of bamboo-cane. What a chasm divides the electric

-  pastime of these naked copper-coloured Indians from the discovery

-  of a metallic conductor discharging its electric shocks, or a

-  pile formed of many chemically-decomposing substances, or a

-  light-engendering magnetic apparatus! In such a chasm lie buried

-  thousands of years, that compose the history of the intellectual

-  development of mankind.--_Humboldt’s Cosmos_, vol. i.

-

-

-THEORY OF THE ELECTRO-MAGNETIC ENGINE.

-

-Several years ago a speculative American set the industrial world of

-Europe in excitement by this proposition. The Magneto-Electric Machines

-often made use of in the case of rheumatic disorders are well known. By

-imparting a swift rotation to the magnet of such a machine, we obtain

-powerful currents of electricity. If these be conducted through water,

-the latter will be reduced to its two components, oxygen and hydrogen.

-By the combustion of hydrogen water is again generated. If this

-combustion takes place, not in atmospheric air, in which oxygen only

-constitutes a fifth part, but in pure oxygen, and if a bit of chalk be

-placed in the flame, the chalk will be raised to a white heat, and give

-us the sun-like Drummond light: at the same time the flame develops a

-considerable quantity of heat. Now the American inventor proposed to

-utilise in this way the gases obtained from electrolytic decomposition;

-and asserted that by the combustion a sufficient amount of heat was

-generated to keep a small steam-engine in action, which again drove his

-magneto-electric machine, decomposed the water, and thus continually

-prepared its own fuel. This would certainly have been the most splendid

-of all discoveries,--a perpetual motion which, besides the force that

-kept it going, generated light like the sun, and warmed all around it.

-The affair, however, failed, as was predicted by those acquainted with

-the physical investigations which bear upon the subject.--_Professor

-Helmholtz._

-

-

-MAGNETIC CLOCK AND WATCH.

-

-In the Museum of the Royal Society are two curiosities of the

-seventeenth century which are objects of much interest in association

-with the electric discoveries of our day. These are a Clock, described

-by the Count Malagatti (who accompanied Cosmo III., Grand Duke of

-Tuscany, to inspect the Museum in 1669) as more worthy of observation

-than all the other objects in the cabinet. Its “movements are derived

-from the vicinity of a loadstone, and it is so adjusted as to discover

-the distance of countries at sea by the longitude.” The analogy

-between this clock and the electric clock of the present day is very

-remarkable. Of kindred interest is “Hook’s Magnetic Watch,” often

-alluded to in the Royal Society’s Journal-book of 1669 as “going slower

-or faster according to the greater or less distance of the loadstone,

-and so moving regularly in any posture.”

-

-

-WHEATSTONE’S ELECTRO-MAGNETIC CLOCK.

-

-In this ingenious invention, the object of Professor Wheatstone was

-to enable a simple clock to indicate exactly the same time in as many

-different places, distant from each other, as may be required. A

-standard clock in an observatory, for example, would thus keep in order

-another clock in each apartment, and that too with such accuracy, that

-_all of them, however numerous, will beat dead seconds audibly with as

-great precision as the standard astronomical time-piece with which

-they are connected_. But, besides this, the subordinate time-pieces

-thus regulated require none of the mechanism for maintaining or

-regulating the power. They consist simply of a face, with its second,

-minute, and hour hands, and a train of wheels which communicate motion

-from the action of the second-hand to that of the hour-hand, in the

-same manner as an ordinary clock-train. Nor is this invention confined

-to observatories and large establishments. The great horologe of St.

-Paul’s might, by a suitable network of wires, or even by the existing

-metallic pipes of the metropolis, be made to command and regulate all

-the other steeple-clocks in the city, and even every clock within the

-precincts of its metallic bounds. As railways and telegraphs extend

-from London nearly to the remotest cities and villages, the sensation

-of time may be transmitted along with the elements of language; and

-the great cerebellum of the metropolis may thus constrain by its

-sympathies, and regulate by its power, the whole nervous system of the

-empire.

-

-

-HOW TO MAKE A COMMON CLOCK ELECTRIC.

-

-M. Kammerer of Belgium effects this by an addition to any clock

-whereby it is brought into contact with the two poles of a galvanic

-battery, the wires from which communicate with a drum moved by the

-clockwork; and every fifteen seconds the current is changed, the

-positive and the negative being transmitted alternately. A wire

-is continued from the drum to the electric clock, the movement of

-which, through the plate-glass dial, is seen to be two pairs of small

-straight electro-magnets, each pair having their ends opposite to the

-other pair, with about half an inch space between. Within this space

-there hangs a vertical steel bar, suspended from a spindle at the

-top. The rod has two slight projections on each side parallel to the

-ends of the wire-coiled magnets. When the electric current comes on

-the wire from the positive end of the battery (through the drum of

-the regulator-clock) the positive magnets attract the bar to it, the

-distance being perhaps the sixteenth of an inch. When, at the end of

-fifteen seconds, the negative pole operates, repulsion takes effect,

-and the bar moves to the opposite side. This oscillating bar gives

-motion to a wheel which turns the minute and hour hands.

-

-M. Kammerer states, that if the galvanic battery be attached to any

-particular standard clock, any number of clocks, wherever placed, in a

-city or kingdom, and communicating with this by a wire, will indicate

-precisely the same time. Such is the precision, that the sounds

-of three clocks thus beating simultaneously have been mistaken as

-proceeding from one clock.

-

-

-DR. FRANKLIN’S ELECTRICAL KITE.

-

-Several philosophers had observed that lightning and electricity

-possessed many common properties; and the light which accompanied

-the explosion, the crackling noise made by the flame, and other

-phenomena, made them suspect that lightning might be electricity in

-a highly powerful state. But this connection was merely the subject

-of conjecture until, in the year 1750, Dr. Franklin suggested an

-experiment to determine the question. While he was waiting for the

-building of a spire at Philadelphia, to which he intended to attach

-his wire, the experiment was successfully made at Marly-la-Ville, in

-France, in the year 1752; when lightning was actually drawn from the

-clouds by means of a pointed wire, and it was proved to be really the

-electric fluid.

-

-  Almost every early electrical discovery of importance was made by

-  Fellows of the Royal Society, and is to be found recorded in the

-  _Philosophical Transactions_. In the forty-fifth volume occurs the

-  first mention of Dr. Franklin’s name, and his theory of positive

-  and negative electricity. In 1756 he was elected into the Society,

-  “without any fee or other payment.” His previous communications

-  to the _Transactions_, particularly the account of his electrical

-  kite, had excited great interest. (_Weld’s History of the

-  Royal Society._) It is thus described by him in a letter dated

-  Philadelphia, October 1, 1752:

-

-  “As frequent mention is made in the public papers from Europe

-  of the success of the Marly-la-Ville experiment for drawing the

-  electric fire from clouds by means of pointed rods of iron erected

-  on high buildings, &c., it may be agreeable to the curious to be

-  informed that the same experiment has succeeded in Philadelphia,

-  though made in a different and more easy manner, which any one may

-  try, as follows:

-

-  Make a small cross of two light strips of cedar, the arms so

-  long as to reach to the four corners of a large thin silk

-  handkerchief when extended. Tie the comers of the handkerchief

-  to the extremities of the cross; so you have the body of a kite,

-  which, being properly accommodated with a tail, loop, and string,

-  will rise in the air like a kite made of paper; but this, being of

-  silk, is fitter to bear the wet and wind of a thunder-gust without

-  tearing. To the top of the upright stick of the cross is to be

-  fixed a very sharp-pointed wire, rising a foot or more above the

-  wood. To the end of the twine, next the band, is to be tied a silk

-  ribbon; and where the twine and silk join a key may be fastened.

-

-  The kite is to be raised when a thunder-gust appears to be coming

-  on, and the person who holds the string must stand within a door

-  or window, or under some cover, so that the silk ribbon may not be

-  wet; and care must be taken that the twine does not touch the frame

-  of the door or window. As soon as any of the thunder-clouds come

-  over the kite, the pointed wire will draw the electric fire from

-  them; and the kite, with all the twine, will be electrified; and

-  the loose filaments of the twine will stand out every way, and be

-  attracted by an approaching finger.

-

-  When the rain has wet the kite and twine, so that it can conduct

-  the electric fire freely, you will find it stream out plentifully

-  from the key on the approach of your knuckle. At this key the phial

-  may be charged; and from electric fire thus obtained spirits may

-  be kindled, and all the other electrical experiments be performed

-  which are usually done by the help of a rubbed-glass globe or tube;

-  and thus the sameness of the electric matter with that of lightning

-  is completely demonstrated.”--_Philosophical Transactions._

-

-Of all this great man’s (Franklin’s) scientific excellencies, the most

-remarkable is the smallness, the simplicity, the apparent inadequacy

-of the means which he employed in his experimental researches. His

-discoveries were all made with hardly any apparatus at all; and if

-at any time he had been led to employ instruments of a somewhat less

-ordinary description, he never rested satisfied until he had, as it

-were, afterwards translated the process by resolving the problem with

-such simple machinery that you might say he had done it wholly unaided

-by apparatus. The experiments by which the identity of lightning and

-electricity was demonstrated were made with a sheet of brown paper, a

-bit of twine or silk thread, and an iron key!--_Lord Brougham._[50]

-

-

-FATAL EXPERIMENT WITH LIGHTNING.

-

-These experiments are not without danger; and a flash of lightning has

-been found to be a very unmanageable instrument. In 1753, M. Richman,

-at St. Petersburg, was making an experiment of this kind by drawing

-lightning into his room, when, incautiously bringing his head too near

-the wire, he was struck dead by the flash, which issued from it like a

-globe of blue fire, accompanied by a dreadful explosion.

-

-

-FARADAY’S ELECTRICAL ILLUSTRATIONS.

-

-The following are selected from the very able series of lectures

-delivered by Professor Faraday at the Royal Institution:

-

-  _The Two Electricities._--After having shown by various experiments

-  the attractions and repulsions of light substances from excited

-  glass and from an excited tube of gutta-percha, Professor Faraday

-  proceeds to point out the difference in the character of the

-  electricity produced by the friction of the two substances. The

-  opposite characters of the electricity evolved by the friction

-  of glass and of that excited by the friction of gutta-percha

-  and shellac are exhibited by several experiments, in which the

-  attraction of the positive and negative electricities to each other

-  and the neutralisation of electrical action on the combination

-  of the two forces are distinctly observable. Though adopting the

-  terms “positive” and “negative” in distinguishing the electricity

-  excited by glass from that excited by gutta-percha and resinous

-  bodies, Professor Faraday is strongly opposed to the Franklinian

-  theory from which these terms are derived. According to Franklin’s

-  view of the nature of electrical excitement, it arises from the

-  disturbance, by friction or other means, of the natural quantity

-  of one electric fluid which is possessed by all bodies; an excited

-  piece of glass having more than its natural share, which has

-  been taken from the rubber, the latter being consequently in a

-  minus or negative state. This theory Professor Faraday considers

-  to be opposed to the distinct characteristic actions of the two

-  forces; and, in his opinion, it is impossible to deprive any body

-  of electricity, and reduce it to the minus state of Franklin’s

-  hypothesis. Taking a Zamboni’s pile, he applies its two ends

-  separately to an electrometer, to show that each end produces

-  opposite kinds of electricity, and that the zero, or absence of

-  electrical excitement, only exists in the centre of the pile. To

-  prove how completely the two electricities neutralise each other,

-  an excited rod of gutta-percha and the piece of flannel with which

-  it has been rubbed are laid on the top of the electrometer without

-  any sign of electricity whilst they are together; but when either

-  is removed, the gold leaves diverge with positive and negative

-  electricity alternately. The Professor dwells strongly on the

-  peculiarity of the dual force of electricity, which, in respect

-  of its duality, is unlike any other force in nature. He then

-  contrasts its phenomena of instantaneous conduction with those of

-  the somewhat analogous force of heat; and he illustrates by several

-  striking experiments the peculiar property which static electricity

-  possesses of being spread only over the surfaces of bodies. A metal

-  ice-pail is placed on an insulated stand and electrified, and a

-  metal ball suspended by a string is introduced, and touches the

-  bottom and sides without having any electricity imparted to it,

-  but on touching the outside it becomes strongly electrical. The

-  experiment is repeated with a wooden tub with the same result;

-  and Professor Faraday mentions the still more remarkable manner

-  in which he has proved the surface distribution of electricity

-  by having a small chamber constructed and covered with tinfoil,

-  which can be insulated; and whilst torrents of electricity are

-  being evolved from the external surface, he enters it with a

-  galvanometer, and cannot perceive the slightest manifestation of

-  electricity within.

-

-  _The Two Threads._--A curious experiment is made with two kinds

-  of thread used as the conducting force. From the electric machine

-  on the table a silk thread is first carried to the indicator a

-  yard or two off, and is shown to be a non-conductor when the glass

-  tube is rubbed and applied to the machine (although the silk, when

-  wetted, conducted); while a metallic thread of the same thickness,

-  when treated in the same way, conducts the force so much as to

-  vehemently agitate the gold leaves within the indicator.

-

-  _Non-conducting Bodies._--The action that occurs in bodies which

-  cannot conduct is the most important part of electrical science.

-  The principle is illustrated by the attraction and repulsion of

-  an electrified ball of gilt paper by a glass tube, between which

-  and the ball a sheet of shellac is suspended. The nearer a ball of

-  another description--an unelectrical insulated body--is brought

-  to the Leyden jar when charged, the greater influence it is seen

-  to possess over the gold leaf within the indicator, by induction,

-  not by conduction. The questions, how electricities attract each

-  other, what kind of electricity is drawn from the machine to the

-  hand, how the hand was electric, are thus illustrated. To show the

-  divers operations of this wonderful force, a tub (a bad conductor)

-  is placed by the electric machine. When the latter is charged, a

-  ball, having been electrified from it, is held in the tub, and

-  rattles against its sides and bottom. On the application of the

-  ball to the indicator, the gold leaf is shown not to move, whereas

-  it is agitated manifestly when the same process is gone through

-  with the exception that the ball is made to touch the outside only

-  of the tub. Similar experiments with a ball in an ice-pail and

-  a vessel of wire-gauze, into the latter of which is introduced a

-  mouse, which is shown to receive no shock, and not to be frightened

-  at all; while from the outside of the vessel electric sparks are

-  rapidly produced. This latter demonstration proves that, as the

-  mouse, so men and women, might be safe inside a building with

-  proper conductors while lightning played about the exterior. The

-  wire-gauze being turned inside out, the principle is shown to be

-  irreversible in spite of the change--what has been the unelectrical

-  inside of the vessel being now, when made the outside portion,

-  capable of receiving and transmitting the power, while the original

-  outside is now unelectrical.

-

-  _Repulsion of Bodies._--A remarkable and playful experiment, by

-  which the repulsion of bodies similarly electrified is illustrated,

-  consists in placing a basket containing a heap of small pieces

-  of paper on an insulated stand, and connecting it with the prime

-  conductor of the electrical machine; when the pieces of paper

-  rise rapidly after each other into the air, and descend on the

-  lecture-table like a fall of snow. The effect is greatly increased

-  when a metal disc is substituted for the basket.

-

-

-ORIGIN OF THE LEYDEN JAR.

-

-Muschenbroek and Linnæus had made various experiments of a strong kind

-with water and wire. The former, as appears from a letter of his to

-Réaumur, filled a small bottle with water, and having corked it up,

-passed a wire through the cork into the bottle. Having rubbed the

-vessel on the outside and suspended it to the electric machine, he was

-surprised to find that on trying to pull the wire out he was subjected

-to an awfully severe shock in his joints and his whole body, such as he

-declared he would not suffer again for any experiment. Hence the Leyden

-jar, which owes its name to the University of Leyden, with which, we

-believe, Muschenbroek was connected.--_Faraday._

-

-

-DANGER TO GUNPOWDER MAGAZINES.

-

-By the illustration of a gas globule, which is ignited from a spark by

-induction, Mr. Faraday has proved in a most interesting manner that the

-corrugated-iron roofs of some gunpowder-magazines,--on the subject of

-which he had often been consulted by the builders, with a view to the

-greater safety of these manufactories,--are absolutely dangerous by the

-laws of induction; as, by the return of induction, while a storm was

-discharging itself a mile or two off, a secondary spark might ignite

-the building.

-

-

-ARTIFICIAL CRYSTALS AND MINERALS.--“THE CROSSE MITE.”

-

-Among the experimenters on Electricity in our time who have largely

-contributed to the “Curiosities of Science,” Andrew Crosse is entitled

-to special notice. In his school-days he became greatly attached to the

-study of electricity; and on settling on his paternal estate, Fyne

-Court, on the Quantock Hills in Somersetshire, he there devoted himself

-to chemistry, mineralogy, and electricity, pursuing his experiments

-wholly independently of theories, and searching only for facts. In

-Holwell Cavern, near his residence, he observed the sides and the roof

-covered with Arragonite crystallisations, when his observations led

-him to conclude that the crystallisations were the effects, at least

-to some extent, of electricity. This induced him to make the attempt

-to form artificial crystals by the same means, which he began in 1807.

-He took some water from the cave, filled a tumbler, and exposed it to

-the action of a voltaic battery excited by water alone, letting the

-platinum-wires of the battery fall on opposite sides of the tumbler

-from the opposite poles of the battery. After ten days’ constant

-action, he produced crystals of carbonate of lime; and on repeating

-the experiment in the dark, he produced them in six days. Thus Mr.

-Crosse simulated in his laboratory one of the hitherto most mysterious

-processes of nature.

-

-He pursued this line of research for nearly thirty years at Fyne Court,

-where his electrical-room and laboratory were on an enormous scale:

-the apparatus had cost some thousands of pounds, and the house was

-nearly full of furnaces. He carried an insulated wire above the tops

-of the trees around his house to the length of a mile and a quarter,

-afterwards shortened to 1800 feet. By this wire, which was brought

-into connection with the apparatus in a chamber, he was enabled to see

-continually the changes in the state of the atmosphere, and could use

-the fluid so collected for a variety of purposes. In 1816, at a meeting

-of country gentlemen, he prophesied that, “by means of electrical

-agency, we shall be able to communicate our thoughts simultaneously

-with the uttermost ends of the earth.” Still, though he foresaw

-the powers of the medium, he did not make any experiments in that

-direction, but confined himself to the endeavour to produce crystals

-of various kinds. He ultimately obtained forty-one mineral crystals,

-or minerals uncrystallised, in the form in which they are produced by

-nature, including one sub-sulphate of copper--an entirely new mineral,

-neither found in nature nor formed by art previously. His belief was

-that even diamonds might be produced in this way.

-

-Mr. Crosse worked alone in his retreat until 1836, when, attending

-the meeting of the British Association at Bristol, he was induced to

-explain his experiments, for which he was highly complimented by Dr.

-Buckland, Dr. Dalton, Professor Sedgwick, and others.[51]

-

-Shortly after Mr. Crosse’s return to Fyne Court, while pursuing his

-experiments for forming crystals from a highly caustic solution out

-of contact with atmospheric air, he was greatly surprised by the

-appearance of an insect. Black flint, burnt to redness and reduced to

-powder, was mixed with carbonate of potash, and exposed to a strong

-heat for fifteen minutes; and the mixture was poured into a black-lead

-crucible in an air furnace. It was reduced to powder while warm,

-mixed with boiling water, kept boiling for some minutes, and then

-hydrochloric acid was added to supersaturation. After being exposed

-to voltaic action for twenty-six days, a perfect insect of the Acari

-tribe made its appearance, and in the course of a few weeks about a

-hundred more. The experiment was repeated in other chemical fluids

-with the like results; and Mr. Weeks of Sandwich afterwards produced

-the Acari inferrocyanerret of potassium. The Acarus of Mr. Crosse was

-found to contribute a new species of that genus, nearly approaching

-the Acari found in cheese and flour, or more nearly, Hermann’s _Acarus

-dimidiatus_.

-

-This discovery occasioned great excitement. The possibility was denied,

-though Mr. Faraday is said to have stated in the same year that he had

-seen similar appearances in his own electrical experiments. Mr. Crosse

-was now accused of impiety and aiming at creation, to which attacks he

-thus replied:

-

-  As to the appearance of the acari under long-continued electrical

-  action, I have never in thought, word, or deed given any one a

-  right to suppose that I considered them as a creation, or even as a

-  formation, from inorganic matter. To create is to form a something

-  out of a nothing. To annihilate is to reduce that something to

-  a nothing. Both of these, of course, can only be the attributes

-  of the Almighty. In fact, I can assure you most sacredly that I

-  have never dreamed of any theory sufficient to account for their

-  appearance. I confess that I was not a little surprised, and am so

-  still, and quite as much as I was when the acari made their first

-  appearance. Again, I have never claimed any merit as attached to

-  these experiments. It was a matter of chance; I was looking for

-  silicious formations, and animal matter appeared instead.

-

-These Acari, if removed from their birthplace, lived and propagated;

-but uniformly died on the first recurrence of frost, and were entirely

-destroyed if they fell back into the fluid whence they arose.

-

-One of Mr. Crosse’s visitors thus describes the vast electrical room at

-Fyne Court:

-

-  Here was an immense number of jars and gallipots, containing fluids

-  on which electricity was operating for the production of crystals.

-  But you are startled in the midst of your observations by the smart

-  crackling sound that attends the passage of the electrical spark;

-  you hear also the rumbling of distant thunder. The rain is already

-  plashing in great drops against the glass, and the sound of the

-  passing sparks continues to startle your ear; you see at the window

-  a huge brass conductor, with a discharging rod near it passing into

-  the floor, and from the one knob to the other sparks are leaping

-  with increasing rapidity and noise, every one of which would kill

-  twenty men at one blow, if they were linked together hand in hand

-  and the spark sent through the circle. From this conductor wires

-  pass off without the window, and the electric fluid is conducted

-  harmlessly away. Mr. Crosse approached the instrument as boldly as

-  if the flowing stream of fire were a harmless spark. Armed with

-  his insulated rod, he sent it into his batteries: having charged

-  them, he showed how wire was melted, dissipated in a moment, by its

-  passage; how metals--silver, gold, and tin--were inflamed and burnt

-  like paper, only with most brilliant hues. He showed you a mimic

-  aurora and a falling-star, and so proved to you the cause of those

-  beautiful phenomena.

-

-Mr. Crosse appears to have produced in all “about 200 varieties of

-minerals, exactly resembling in all respects similar ones found in

-nature.” He tried also a new plan of extracting gold from its ores

-by an electrical process, which succeeded, but was too expensive

-for common use. He was in the habit of saying that he could, like

-Archimedes, move the world “if he were able to construct a battery at

-once cheap, powerful, and durable.” His process of extracting metals

-from their ores has been patented. Among his other useful applications

-of electricity are the purifying by its means of brackish or sea-water,

-and the improving bad wine and brandy. He agreed with Mr. Quekett

-in thinking that it is by electrical action that silica and other

-mineral substances are carried into and assimilated by plants. Negative

-electricity Mr. Crosse found favourable to no plants except fungi;

-and positive electricity he ascertained to be injurious to fungi, but

-favourable to every thing else.

-

-Mr. Crosse died in 1855. His widow has published a very interesting

-volume of _Memorials_ of the ingenious experimenter, from which we

-select the following:

-

-  On one occasion Mr. Crosse kept a pair of soles under the electric

-  action for three months; and at the end of that time they were

-  sent to a friend, whose domestics knew nothing of the experiment.

-  Before the cook dressed them, her master asked her whether she

-  thought they were fresh, as he had some doubts. She replied that

-  she was sure they were fresh; indeed, she said she could swear

-  that they were alive yesterday! When served at table they appeared

-  like ordinary fish; but when the family attempted to eat them,

-  they were found to be perfectly tasteless--the electric action had

-  taken away all the essential oil, leaving the fish unfit for food.

-  However, the process is exceedingly useful for keeping fish, meat,

-  &c. fresh and _good_ for ten days or a fortnight. I have never

-  heard a satisfactory explanation of the cause of the antiseptic

-  power communicated to water by the passage of the electric current.

-  Whether ozone has not something to do with it, may be a question.

-  The same effect is produced whichever two dissimilar metals are

-  used.

-

-

-

-

-The Electric Telegraph.

-

-

-ANTICIPATIONS OF THE ELECTRIC TELEGRAPH.

-

-The great secret of ubiquity, or at least of instantaneous

-transmission, has ever exercised the ingenuity of mankind in various

-romantic myths; and the discovery of certain properties of the

-loadstone gave a new direction to these fancies.

-

-The earliest anticipation of the Electric Telegraph of this purely

-fabulous character forms the subject of one of the _Prolusiones

-Academicæ_ of the learned Italian Jesuit Strada, first published at

-Rome in the year 1617. Of this poem a free translation appeared in

-1750. Strada’s fancy was this: “There is,” he supposes, “a species of

-loadstone which possesses such virtue, that if two needles be touched

-with it, and then balanced on separate pivots, and the one be turned in

-a particular direction, the other will sympathetically move parallel

-to it. He then directs each of these needles to be poised and mounted

-parallel on a dial having the letters of the alphabet arranged round

-it. Accordingly, if one person has one of the dials, and another the

-other, by a little pre-arrangement as to details a correspondence can

-be maintained between them at any distance by simply pointing the

-needles to the letters of the required words. Strada, in his poetical

-reverie, dreamt that some such sympathy might one day be found to hold

-up the Magnesian Stone.”

-

-Strada’s conceit seems to have made a profound impression on the

-master-minds of the day. His poem is quoted in many works of the

-seventeenth and eighteenth centuries; and Bishop Wilkins, in his book

-on Cryptology, is strangely afraid lest his readers should mistake

-Strada’s fancy for fact. Wilkins writes: “This invention is altogether

-imaginary, having no foundation in any real experiment. You may see it

-frequently confuted in those that treat concerning magnetical virtues.”

-

-Again, Addison, in the 241st No. of the _Spectator_, 1712, describes

-Strada’s “Chimerical correspondence,” and adds that, “if ever this

-invention should be revived or put in practice,” he “would propose

-that upon the lover’s dial-plate there should be written not only the

-four-and-twenty letters, but several entire words which have always a

-place in passionate epistles, as flames, darts, die, language, absence,

-Cupid, heart, eyes, being, drown, and the like. This would very much

-abridge the lover’s pains in this way of writing a letter, as it would

-enable him to express the most useful and significant words with a

-single touch of the needle.”

-

-After Strada and his commentators comes Henry Van Etten, who shows how

-“Claude, being at Paris, and John at Rome, might converse together, if

-each had a needle touched by a stone of such virtue that as one moved

-itself at Paris the other should be moved at Rome:” he adds, “it is

-a fine invention, but I do not think there is a magnet in the world

-which has such virtue; besides, it is inexpedient, for treasons would

-be too frequent and too much protected. (_Recréations Mathématiques_:

-see 5th edition, Paris, 1660, p. 158.) Sir Thomas Browne refers

-to this “conceit” as “excellent, and, if the effect would follow,

-somewhat divine;” but he tried the two needles touched with the same

-loadstone, and placed in two circles of letters, “one friend keeping

-one and another the other, and agreeing upon an hour when they will

-communicate,” and found the tradition a failure that, “at what distance

-of place soever, when one needle shall be removed unto any letter, the

-other, by a wonderful sympathy, will move unto the same.” (See _Vulgar

-Errors_, book ii. ch. iii.)

-

-Glanvill’s _Vanity of Dogmatizing_, a work published in 1661, however,

-contains the most remarkable allusion to the prevailing telegraphic

-fancy. Glanvill was an enthusiast, and he clearly predicts the

-discovery and general adoption of the electric telegraph. “To confer,”

-he says, “at the distance of the Indies by sympathetic conveyance may

-be as usual to future times as to us in a literary correspondence.” By

-the word “sympathetic” he evidently intended to convey magnetic agency;

-for he subsequently treats of “conference at a distance by impregnated

-needles,” and describes the device substantially as it is given by Sir

-Thomas Browne, adding, that though it did not then answer, “by some

-other such way of magnetic efficiency it may hereafter with success be

-attempted, when magical history shall be enlarged by riper inspection;

-and ’tis not unlikely but that present discoveries might be improved

-to the performance.” This may be said to close the most speculative or

-mythical period in reference to the subject of electro-telegraphy.

-

-Electricians now began to be sedulous in their experiments upon the

-new force by friction, then the only known method of generating

-electricity. In 1729, Stephen Gray, a pensioner of the Charter-house,

-contrived a method of making electrical signals through a wire 765

-feet long; yet this most important experiment did not excite much

-attention. Next Dr. Watson, of the Royal Society, experimented on the

-possibility of transmitting electricity through a large circuit from

-the simple fact of Le Monnier’s account of his feeling the stroke

-of the electrified fires through two of the basins of the Tuileries

-(which occupy nearly an acre), by means of an iron chain lying upon

-the ground and stretched round half their circumference. In 1745, Dr.

-Watson, assisted by several members of the Royal Society, made a series

-of experiments to ascertain how far electricity could be conveyed by

-means of conductors. “They caused the shock to pass across the Thames

-at Westminster Bridge, the circuit being completed by making use of the

-river for one part of the chain of communication. One end of the wire

-communicated with the coating of a charged phial, the other being held

-by the observer, who in his other hand held an iron rod which he dipped

-into the river. On the opposite side of the river stood a gentleman,

-who likewise dipped an iron rod in the river with one hand, and in the

-other held a wire the extremity of which might be brought into contact

-with the wire of the phial. Upon making the discharge, the shock was

-felt simultaneously by both the observers.” (_Priestley’s History of

-Electricity._) Subsequently the same parties made experiments near

-Shooter’s Hill, when the wires formed a circuit of four miles, and

-conveyed the shock with equal facility,--“a distance which without

-trial,” they observed, “was too great to be credited.”[52] These

-experiments in 1747 established two great principles: 1, that the

-electric current is transmissible along nearly two miles and a half of

-iron wire; 2, that the electric current may be completed by burying the

-poles in the earth at the above distance.

-

-In the following year, 1748, Benjamin Franklin performed his celebrated

-experiments on the banks of the Schuylkill, near Philadelphia; which

-being interrupted by the hot weather, they were concluded by a picnic,

-when spirits were fired by an electric spark sent through a wire in the

-river, and a turkey was killed by the electric shock, and roasted by

-the electric jack before a fire kindled by the electrified bottle.

-

-In the year 1753, there appeared in the _Scots’ Magazine_, vol. xv.,

-definite proposals for the construction of an electric telegraph,

-requiring as many conducting wires as there are letters in the

-alphabet; it was also proposed to converse by chimes, by substituting

-bells for the balls. A similar system of telegraphing was next invented

-by Joseph Bozolus, a Jesuit, at Rome; and next by the great Italian

-electrician Tiberius Cavallo, in his treatise on Electricity.

-

-In 1787, Arthur Young, when travelling in France, saw a model working

-telegraph by M. Lomond: “You write two or three words on a paper,” says

-Young; “he takes it with him into a room, and turns a machine enclosed

-in a cylindrical case, at the top of which is an electrometer--a

-small fine pith-ball; a wire connects with a similar cylinder and

-electrometer in a distant apartment; and his wife, by remarking the

-corresponding motions of the ball, writes down the words they indicate:

-from which it appears that he has formed an alphabet of motions. As the

-length of the wire makes no difference in the effect, a correspondence

-might be carried on at any distance. Whatever the use may be, the

-invention is beautiful.”

-

-We now reach a new epoch in the scientific period--the discovery of the

-Voltaic Pile. In 1794, according to _Voigt’s Magazine_, Reizen made

-use of the electric spark for the telegraph; and in 1798 Dr. Salva

-of Madrid constructed a similar telegraph, which the Prince of Peace

-subsequently exhibited to the King of Spain with great success.

-

-In 1809, Soemmering exhibited a telegraphic apparatus worked by

-galvanism before the Academy of Sciences at Munich, in which the mode

-of signalling consisted in the development of gas-bubbles from the

-decomposition of water placed in a series of glass tubes, each of which

-denoted a letter of the alphabet. In 1813, Mr. Sharpe, of Doe Hill near

-Alfreton, devised a _voltaic_-electric telegraph, which he exhibited to

-the Lords of the Admiralty, who spoke approvingly of it, but declined

-to carry it into effect. In the following year, Soemmering exhibited a

-_voltaic_-electric telegraph of his own construction, which, however,

-was open to the objection of there being as many wires as signs or

-letters of the alphabet.

-

-The next invention is of much greater importance. Upon the suggestion

-of Cavallo, already referred to, Francis Ronalds constructed a perfect

-electric telegraph, employing frictional electricity notwithstanding

-Volta’s discoveries had been known in England for sixteen years. This

-telegraph was exhibited at Hammersmith in 1816:[53] it consisted of

-a single insulated wire, the indication being by pith-balls in front

-of a dial. When the wire was charged, the balls were divergent, but

-collapsed when the wire was discharged; at the same time were employed

-two clocks, with lettered discs for the signals. “If, as Paley asserts

-(and Coleridge denies), ‘he alone discovers who proves,’ Ronalds is

-entitled to the appellation of the first discoverer of an efficient

-electric telegraph.” (_Saturday Review_, No. 147[54]) Nevertheless

-the Government of the day refused to avail itself of this admirable

-contrivance.

-

-In 1819, Oersted made his great discovery of the deflection, by a

-current of electricity, of a magnetic needle at right angles to such

-current. Dr. Hamel of St. Petersburg states that Baron Schilling was

-the first to apply Oersted’s discovery to telegraphy; Ampère had

-previously suggested it, but his plan was very complicated, and Dr.

-Hamel maintains that Schilling first realised the idea by actually

-producing an electro-magnetic telegraph simpler in construction

-than that which Ampère had _imagined_. In 1836, Professor Muncke of

-Heidelberg, who had inspected Schilling’s telegraphic apparatus,

-explained the same to William Fothergill Cooke, who in the following

-year returned to England, and subsequently, with Professor Wheatstone,

-laboured simultaneously for the introduction of the electro-magnetic

-telegraph upon the English railways; the first patent for which was

-taken out in the joint names of these two gentlemen.

-

-In 1844, Professor Wheatstone, with one of his telegraphs, formed a

-communication between King’s College and the lofty shot-tower on the

-opposite bank of the Thames: the wire was laid along the parapets of

-the terrace of Somerset House and Waterloo Bridge, and thence to the

-top of the tower, about 150 feet high, where a telegraph was placed;

-the wire then descended, and a plate of zinc attached to its extremity

-was plunged into the mud of the river, whilst a similar plate attached

-to the extremity at the north side was immersed in the water. The

-circuit was thus completed by the entire breadth of the Thames, and the

-telegraph acted as well as if the circuit were entirely metallic.

-

-Shortly after this experiment, Professor Wheatstone and Mr. Cooke laid

-down the first working electric telegraph on the Great Western Railway,

-from Paddington to Slough.

-

-

-ELECTRIC GIRDLE FOR THE EARTH.

-

-One of our most profound electricians is reported to have exclaimed:

-“Give me but an unlimited length of wire, with a small battery, and I

-will girdle the universe with a sentence in forty minutes.” Yet this is

-no vain boast; for so rapid is the transition of the electric current

-along the line of the telegraph wire, that, supposing it were possible

-to carry the wires eight times round the earth, the transit would

-occupy but _one second of time_!

-

-

-CONSUMPTION OF THE ELECTRIC TELEGRAPH.

-

-It is singular to see how this telegraphic agency is measured by the

-chemical consumption of zinc and acid. Mr. Jones (who has written a

-work upon the Electric Telegraphs of America) estimates that to work

-12,000 miles of telegraph about 3000 zinc cups are used to hold the

-acid: these weigh about 9000 lbs., and they undergo decomposition by

-the galvanic action in about six months, so that 18,000 lbs. of zinc

-are consumed in a year. There are also about 3600 porcelain cups to

-contain nitric acid; it requires 450 lbs. of acid to charge them once,

-and the charge is renewed every fortnight, making about 12,000 lbs. of

-nitric acid in a year.

-

-

-TIME LOST IN ELECTRIC MESSAGES.

-

-Although it may require an hour, or two or three hours, to transmit

-a telegraphic message to a distant city, yet it is the mechanical

-adjustment by the sender and receiver which really absorbs this time;

-the actual transit is practically instantaneous, and so it would be

-from here to the antipodes, so far as the current itself is concerned.

-

-

-THE ELECTRIC TELEGRAPH IN ASTRONOMY AND THE DETERMINATION OF LONGITUDE.

-

-The Electric Telegraph has become an instrument in the hands of the

-astronomer for determining the difference of longitude between two

-observatories. Thus in 1854 the difference of longitude between London

-and Paris was determined within a limit of error which amounted barely

-to a quarter of a second. The sudden disturbances of the magnetic

-needle, when freely suspended, which seem to take place simultaneously

-over whole continents, if not over the whole globe, from some

-unexplained cause, are pointed out as means by which the differences of

-longitude between the magnetic observatories may possibly be determined

-with greater precision than by any yet known method.

-

-So long ago as 1839 Professor Morse suggested some experiments for

-the determination of Longitudes; and in June 1844 the difference of

-longitude between Washington and Baltimore was determined by electric

-means under his direction. Two persons were stationed at these two

-towns, with clocks carefully adjusted to the respective spots; and

-a telegraphic signal gave the means of comparing the two clocks

-at a given instant. In 1847 the relative longitudes of New York,

-Philadelphia, and Washington were determined by means of the electric

-telegraph by Messrs. Keith, Walker, and Loomis.

-

-

-NON-INTERFERENCE OF GALVANIC WAVES ON THE SAME WIRE.

-

-One of the most remarkable facts in the economy of the telegraph is,

-that the line, when connected with a battery in action, propagates

-the hydro-galvanic waves in either direction without interference. As

-several successive syllables of sound may set out in succession from

-the same place, and be on their way at the same time, to a listener at

-a distance, so also, where the telegraph-line is long enough, several

-waves may be on their way from the signal station before the first one

-reaches the receiving station; two persons at a distance may pronounce

-several syllables at the same time, and each hear those emitted by the

-other. So, on a telegraph-line of two or three thousand miles in length

-in the air, and the same in the ground, two operators may at the same

-instant commence a series of several dots and lines, and each receive

-the other’s writings, though the waves have crossed each other on the

-way.

-

-

-EFFECT OF LIGHTNING UPON THE ELECTRIC TELEGRAPH.

-

-In the storm of Sunday April 2, 1848, the lightning had a very

-considerable effect on the wires of the electric telegraph,

-particularly on the line of railway eastward from Manchester to

-Normanton. Not only were the needles greatly deflected, and their power

-of answering to the handles considerably weakened, but those at the

-Normanton station were found to have had their poles reversed by some

-action of the electric fluid in the atmosphere. The damage, however,

-was soon repaired, and the needles again put in good working order.

-

-

-ELECTRO-TELEGRAPHIC MESSAGE TO THE STARS.

-

-The electric fluid travels at the mean rate of 20,000 miles in a

-second under ordinary circumstances; therefore, if it were possible to

-establish a telegraphic communication with the star 61 Cygni, it would

-require ninety years to send a message there.

-

-Professor Henderson and Mr. Maclear have fully confirmed the annual

-parallax of α Centauri to amount to a second of arc, which gives about

-twenty billions of miles as its distance from our system; a ray of

-light would arrive from α Centauri to us in little more than three

-years, and a telegraphic despatch would arrive there in thirty years.

-

-

-THE ATLANTIC TELEGRAPH.

-

-The telegraphic communication between England and the United States

-is so grand a conception, that it would be impossible to detail its

-scientific and mechanical relations within the limits of the present

-work. All that we shall attempt, therefore, will be to glance at a few

-of the leading operations.

-

-In the experiments made before the Atlantic Telegraph was finally

-decided on, 2000 miles of subterranean and submarine telegraphic wires,

-ramifying through England and Ireland and under the waters of the

-Irish Sea, were specially connected for the purpose; and through this

-distance of 2000 miles 250 distinct signals were recorded and printed

-in one minute.

-

-First, as to the _Cable_. In the ordinary wires by the side of

-a railway the electric current travels on with the speed of

-lightning--uninterrupted by the speed of lightning; but when a wire

-is encased in gutta-percha, or any similar covering, for submersion

-in the sea, new forces come into play. The electric excitement of the

-wire acts by induction, through the envelope, upon the particles of

-water in contact with that envelope, and calls up an electric force

-of an opposite kind. There are two forces, in fact, pulling against

-each other through the gutta-percha as a neutral medium,--that is,

-the electricity in the wire, and the opposite electricity in the film

-of water immediately surrounding the cable; and to that extent the

-power of the current in the enclosed wire is weakened. A submarine

-cable, when in the water, is virtually _a lengthened-out Leyden jar_;

-it transmits signals while being charged and discharged, instead of

-merely allowing a stream to flow evenly along it: it is a _bottle_

-for holding electricity rather than a _pipe_ for carrying it; and

-this has to be filled for every time of using. The wire being carried

-underground, or through the water, the speed becomes quite measurable,

-say a thousand miles in a second, instead of two hundred thousand,

-owing to the retardation by induced or retrograde currents. The energy

-of the currents and the quality of the wire also affect the speed.

-Until lately it was supposed that the wire acts only as a _conductor_

-of electricity, and that a long wire must produce a weaker effect than

-a short one, on account of the consequent attenuation of the electrical

-influence; but it is now known that, the cable being a _reservoir_ as

-well as a conductor, its electrical supply is increased in proportion

-to its length.

-

-The electro-magnetic current is employed, since it possesses a treble

-velocity of transmission, and realises consequently _a threefold

-working speed_ as compared with simple voltaic electricity. Mr. Wildman

-Whitehouse has determined by his ingenious apparatus that the speed

-of the voltaic current might be raised under special circumstances

-to 1800 miles per second; but that of the induced current, or the

-electro-magnetic, might be augmented to 6000 miles per second.

-

-Next as to a _Quantity Battery_ employed in these investigations. To

-effect a charge, and transmit a current through some thousand miles of

-the Atlantic Cable, Mr. Whitehouse had a piece of apparatus prepared

-consisting of twenty-five pairs of zinc and silver plates about the

-20th part of a square inch large, and the pairs so arranged that

-they would hold a drop of acidulated water or brine between them. On

-charging this Lilliputian battery by dipping the plates in salt and

-water, messages were sent from it through a thousand miles of cable

-with the utmost ease; and not only so,--pair after pair was dropped

-out from the series, the messages being still sent on with equal

-facility, until at last only a single pair, charged by one single drop

-of liquid, was used. Strange to say, with this single pair and single

-drop distinct signals were effected through the thousand miles of the

-cable! Each signal was registered at the end of the cable in less than

-three seconds of time.

-

-The entire length of wire, iron and copper, spun into the cable amounts

-to 332,500 miles, a length sufficient to engirdle the earth thirteen

-times. The cable weighs from 19 cwt. to a ton per mile, and will bear a

-strain of 5 tons.

-

-The _Perpetual Maintenance Battery_, for working the cable at the

-bottom of the sea, consists of large plates of platinated silver and

-amalgamated zinc, mounted in cells of gutta-percha. The zinc plates in

-each cell rest upon a longitudinal bar at the bottom, and the silver

-plates hang upon a similar bar at the top of the cell; so that there

-is virtually but a single stretch of silver and a single stretch of

-zinc in operation. Each of the ten cells contains 2000 square inches

-of acting surface; and the combination is so powerful, that when the

-broad strips of copper-plate which form the polar extensions are

-brought into contact or separated, brilliant flashes are produced,

-accompanied by a loud crackling sound. The points of large pliers

-are made red-hot in five seconds when placed between them, and even

-screws burn with vivid scintillation. The cost of maintaining this

-magnificent ten-celled Titan battery at work does not exceed a shilling

-per hour. The voltaic current generated in this battery is not,

-however, the electric stream to be sent across the Atlantic, but is

-only the primary power used to call up and stimulate the energy of a

-more speedy traveller by a complicated apparatus of “Double Induction

-Coils.” Nor is the transmission-current generated in the inner wire

-of the double induction coil,--and which becomes weakened when it has

-passed through 1800 or 1900 miles,--set to work to print or record the

-signals transmitted. This weakened current merely opens and closes the

-outlet of a fresh battery, which is to do the printing labour. This

-relay-instrument (as it is called), which consists of a temporary and

-permanent magnet, is so sensitive an apparatus, that it may be put in

-action by a fragment of zinc and a sixpence pressed against the tongue.

-

-The attempts to lay the cable in August 1857 failed through stretching

-it so tightly that it snapped and went to the bottom, at a depth of

-12,000 feet, forty times the height of St. Paul’s.

-

-This great work was resumed in August 1858; and on the 5th the first

-signals were received through _two thousand and fifty miles_ of the

-Atlantic Cable. And it is worthy of remark, that just 111 years

-previously, on the 5th of August 1747, Dr. Watson astonished the

-scientific world by practically proving that the electric current could

-be transmitted through a _wire hardly two miles and a half long_.[55]

-

-

-

-

-Miscellanea.

-

-

-HOW MARINE CHRONOMETERS ARE RATED AT THE ROYAL OBSERVATORY, GREENWICH.

-

-The determination of the Longitude at Sea requires simply accurate

-instruments for the measurement of the positions of the heavenly

-bodies, and one or other of the two following,--either perfectly

-correct watches--or chronometers, as they are now called--or perfectly

-accurate tables of the lunar motions.

-

-So early as 1696 a report was spread among the members of the Royal

-Society that Sir Isaac Newton was occupied with the problem of finding

-the longitude at sea; but the rumour having no foundation, he requested

-Halley to acquaint the members “that he was not about it.”[56] (_Sir

-David Brewster’s Life of Newton._)

-

-In 1714 the legislature of Queen Anne passed an Act offering a reward

-of 20,000_l._ for the discovery of the longitude, the problem being

-then very inaccurately solved for want of good watches or lunar tables.

-About the year 1749, the attention of the Royal Society was directed

-to the improvements effected in the construction of watches by John

-Harrison, who received for his inventions the Copley Medal. Thus

-encouraged, Harrison continued his labours with unwearied diligence,

-and produced in 1758 a timekeeper which was sent for trial on a voyage

-to Jamaica. After 161 days the error of the instrument was only 1m

-5s, and the maker received from the nation 5000_l._ The Commissioners

-of the Board of Longitude subsequently required Harrison to construct

-under their inspection chronometers of a similar nature, which were

-subjected to trial in a voyage to Barbadoes, and performed with such

-accuracy, that, after having fully explained the principle of their

-construction to the commissioners, they awarded him 10,000_l._ more;

-at the same time Euler of Berlin and the heirs of Mayer of Göttingen

-received each 3000_l._ for their lunar tables.

-

-  The account of the trial of Harrison’s watch is very interesting.

-  In April 1766, by desire of the Commissioners of the Board, the

-  Lords of the Admiralty delivered the watch into the custody of

-  the Astronomer-Royal, the Rev. Dr. Nevil Maskelyne. It was then

-  placed at the Royal Observatory at Greenwich, in a box having two

-  different locks, fixed to the floor or wainscot, with a plate of

-  glass in the lid of the box, so that it might be compared as often

-  as convenient with the regulator and the variation set down. The

-  form observed by Mr. Harrison in winding up the watch was exactly

-  followed; and an officer of Greenwich Hospital attended every day,

-  at a stated hour, to see the watch wound up, and its comparison

-  with the regulator entered. A key to one of the locks was kept at

-  the Hospital for the use of the officer, and the other remained

-  at the Observatory for the use of the Astronomer-Royal or his

-  assistant.

-

-  The watch was then tried in various positions till the beginning

-  of July; and from thence to the end of February following in a

-  horizontal position with its face upwards.

-

-  The variation of the watch was then noted down, and a register was

-  kept of the barometer and thermometer; and the time of comparing

-  the same with the regulator was regularly kept, and attested by

-  the Astronomer-Royal or his assistant and such of the officers as

-  witnessed the winding-up and comparison of the watch.

-

-  Under these conditions Harrison’s watch was received by the

-  Astronomer-Royal at the Admiralty on May 5, 1766, in the presence

-  of Philip Stephens, Esq., Secretary of the Admiralty; Captain

-  Baillie, of the Royal Hospital, Greenwich; and Mr. Kendal the

-  watchmaker, who accompanied the Astronomer-Royal to Greenwich, and

-  saw the watch started and locked up in the box provided for it. The

-  watch was then compared with the transit clock daily, and wound up

-  in the presence of the officer of Greenwich Hospital. From May 5 to

-  May 17 the watch was kept in a horizontal position with its face

-  upwards; from May 18 to July 6 it was tried--first inclined at an

-  angle of 20° to the horizon, with the face upwards, and the hours

-  12, 6, 3, and 9, highest successively; then in a vertical position,

-  with the same hours highest in order; lastly, in a horizontal

-  position with the face downwards. From July 16, 1766, to March 4,

-  1767, it was always kept in a horizontal position with its face

-  upwards, lying upon the same cushion, and in the same box in which

-  Mr. Harrison had kept it in the voyage to Barbadoes.

-

-  From the observed transits of the sun over the meridian, according

-  to the time of the regulator of the Observatory, together with

-  the attested comparisons of Mr. Harrison’s watch with the transit

-  clock, the watch was found too fast on several days as follows:

-

-                                h.  m.   s.

-    1766. May 6      too fast   0   0  16·2

-          May 17        ”       0   3  51·8

-          July 6        ”       0  14  14·0

-          Aug. 6        ”       0  23  58·4

-          Sept. 17      ”       0  32  15·6

-          Oct. 29       ”       0  42  20·9

-          Dec. 10       ”       0  54  46·8

-    1767. Jan. 21       ”       1   0  28·6

-          March 4       ”       1  11  23·0

-

-  From May 6, which was the day after the watch arrived at the Royal

-  Observatory, to March 4, 1767, there were six periods of six weeks

-  each in which the watch was tried in a horizontal position; when

-  the gaining in these several periods was as follows:

-

-    During the first 6 weeks it gained 13m 20s, answering to 3° 20′

-    of longitude.

-

-    In the 2d period of 6

-      weeks (from Aug. 6 to        ”    8  17       ”        2   4

-      Sept. 17)

-

-    In the 3d period (from         ”   10   5       ”        2  31

-      Sept. 17 to Oct. 29)

-

-    In the 4th period (from        ”   12  26       ”        3   6

-      Oct. 29 to Dec. 20)

-

-    In the 5th period (from        ”    5  42       ”        1  25

-      Dec. 20 to Jan. 21)

-

-    In the 6th period (from        ”   10  54       ”        2  43

-      Jan. 21 to Mar. 4)

-

-It was thence concluded that Mr. Harrison’s watch could not be depended

-upon to keep the longitude within a West-India voyage of six weeks, nor

-to keep the longitude within half a degree for more than a fortnight;

-and that it must be kept in a place where the temperature was always

-some degrees above freezing.[57] (However, Harrison’s watch, which was

-made by Mr. Kendal subsequently, succeeded so completely, that after it

-had been round the world with Captain Cook, in the years 1772-1775, the

-second 10,000_l._ was given to Harrison.)

-

-In the Act of 12th Queen Anne, the comparison of chronometers was not

-mentioned in reference to the Observatory duties; but after this time

-they became a serious charge upon the Observatory, which, it must be

-admitted, is by far the best place to try chronometers: the excellence

-of the instruments, and the frequent observations of the heavenly

-bodies over the meridian, will always render the rate of going of the

-Observatory clock better known than can be expected of the clock in

-most other places.

-

-After Mr. Harrison’s watch was tried, some watches by Earnshaw, Mudge,

-and others, were rated and examined by the Astronomer-Royal.

-

-At the Royal Observatory, Greenwich, there are frequently above 100

-chronometers being rated, and there have been as many as 170 at one

-time. They are rated daily by two observers, the process being as

-follows. At a certain time every day two assistants in charge repair

-to the chronometer-room, where is a time-piece set to true time; one

-winds up each with its own key, and the second follows after some

-little time and verifies the fact that each is wound. One assistant

-then looks at each watch in succession, counting the beats of the clock

-whilst he compares the chronometer by the eye; and in the course of a

-few seconds he calls out the second shown by the chronometer when the

-clock is at a whole minute. This number is entered in a book by the

-other assistant, and so on till all the chronometers are compared.

-Then the assistants change places, the second comparing and the first

-writing down. From these daily comparisons the daily rates are deduced,

-by which the goodness of the watch is determined. The errors are of

-two classes--that of general bad workmanship, and that of over or

-under correction for temperature. In the room is an apparatus in which

-the watch may be continually kept at temperatures exceeding 100° by

-artificial heat; and outside the window of the room is an iron cage,

-in which they are subjected to low temperatures. The very great care

-taken with all chronometers sent to the Royal Observatory, as well as

-the perfect impartiality of the examination which each receives, afford

-encouragement to their manufacture, and are of the utmost importance to

-the safety and perfection of navigation.

-

-We have before us now the Report of the Astronomer-Royal on the Rates

-of Chronometers in the year 1854, in which the following are the

-successive weekly sums of the daily rates of the first there mentioned:

-

-    Week ending              secs.

-

-    Jan. 21, loss in the week 2·2

-     ”   28         ”         4·0

-    Feb.  4         ”         1·1

-     ”   11         ”         5·0

-     ”   18         ”         4·9

-     ”   25         ”         5·5

-    Mar.  4         ”         6·0

-     ”   11         ”         6·0

-     ”   18         ”         1·5

-     ”   25         ”         4·5

-    Apr.  1         ”         4·0

-     ”    8         ”         1·5

-     ”   15, gain in the week 0·4

-    Apr. 22,        ”         2·6

-     ”   29, loss in the week 1·4

-    May   6         ”         2·1

-     ”   13         ”         3·0

-     ”   20         ”         5·1

-     ”   27         ”         3·3

-    June  3         ”         2·8

-     ”   10         ”         1·8

-     ”   17         ”         2·0

-     ”   24         ”         3·0

-    July  1         ”         2·5

-     ”    8         ”         1·2

-

-Till February 4 the watch was exposed to the external air outside a

-north window; from February 5 to March 4 it was placed in the chamber

-of a stove heated by gas to a moderate temperature; and from April

-29 to May 20 it was placed in the chamber when heated to a high

-temperature.

-

-The advance in making chronometers since Harrison’s celebrated watch

-was tried at the Royal Observatory, more than ninety years since, may

-be judged by comparing its rates with those above.

-

-

-GEOMETRY OF SHELLS.

-

-There is a mechanical uniformity observable in the description of

-shells of the same species which at once suggests the probability that

-the generating figure of each increases, and that the spiral chamber of

-each expands itself, according to some simple geometrical law common

-to all. To the determination of this law the operculum lends itself,

-in certain classes of shells, with remarkable facility. Continually

-enlarged by the animal, as the construction of its shell advances so as

-to fill up its mouth, the operculum measures the progressive widening

-of the spiral chamber by the progressive stages of its growth.

-

-       *       *       *       *       *

-

-The animal, as he advances in the construction of his shell, increases

-continually his operculum, so as to adjust it to his mouth. He

-increases it, however, not by additions made at the same time all round

-its margin, but by additions made only on one side of it at once. One

-edge of the operculum thus remains unaltered as it is advanced into

-each new position, and placed in a newly-formed section of the chamber

-similar to the last but greater than it.

-

-That the same edge which fitted a portion of the first less section

-should be capable of adjustment so as to fit a portion of the next

-similar but greater section, supposes a geometrical provision in the

-curved form of the chamber of great complication and difficulty. But

-God hath bestowed upon this humble architect the practical skill of

-the learned geometrician; and he makes this provision with admirable

-precision in that curvature of the logarithmic spiral which he gives to

-the section of the shell. This curvature obtaining, he has only to turn

-his operculum slightly round in its own place, as he advances it into

-each newly-formed portion of his chamber, to adapt one margin of it to

-a new and larger surface and a different curvature, leaving the space

-to be filled up by increasing the operculum wholly on the outer margin.

-

-       *       *       *       *       *

-

-Why the Mollusks, who inhabit turbinated and discoid shells, should, in

-the progressive increase of their spiral dwellings, affect the peculiar

-law of the logarithmic spiral, is easily to be understood. Providence

-has subjected the instinct which shapes out each to a rigid uniformity

-of operation.--_Professor Mosely_: _Philos. Trans._ 1838.

-

-

-HYDRAULIC THEORY OF SHELLS.

-

-How beautifully is the wisdom of God developed in shaping out and

-moulding shells! and especially in the particular value of the constant

-angle which the spiral of each species of shell affects,--a value

-connected by a necessary relation with the economy of the material

-of each, and with its stability and the conditions of its buoyancy.

-Thus the shell of the _Nautilus Pompilius_ has, hydrostatically, an

-A-statical surface. If placed with any portion of its surface upon the

-water, it will immediately turn over towards its smaller end, and rest

-only on its mouth. Those conversant with the theory of floating bodies

-will recognise in this an interesting property.--_Ibid._

-

-

-SERVICES OF SEA-SHELLS AND ANIMALCULES.

-

-Dr. Maury is disposed to regard these beings as having much to do in

-maintaining the harmonies of creation, and the principles of the most

-admirable compensation in the system of oceanic circulation. “We may

-even regard them as regulators, to some extent, of climates in parts

-of the earth far removed from their presence. There is something

-suggestive both of the grand and the beautiful in the idea that while

-the insects of the sea are building up their coral islands in the

-perpetual summer of the tropics, they are also engaged in dispensing

-warmth to distant parts of the earth, and in mitigating the severe cold

-of the polar winter.”

-

-

-DEPTH OF THE PRIMEVAL SEAS.

-

-Professor Forbes, in a communication to the Royal Society, states that

-not only the colour of the shells of existing mollusks ceases to be

-strongly marked at considerable depths, but also that well-defined

-patterns are, with very few and slight exceptions, presented only by

-testacea inhabiting the littoral, circumlittoral, and median zones.

-In the Mediterranean, only one in eighteen of the shells taken from

-below 100 fathoms exhibit any markings of colour, and even the few

-that do so are questionable inhabitants of those depths. Between 30

-and 35 fathoms, the proportion of marked to plain shells is rather

-less than one in three; and between the margin and two fathoms the

-striped or mottled species exceed one-half of the total number. In our

-own seas, Professor Forbes observes that testacea taken from below 100

-fathoms, even when they are individuals of species vividly striped or

-banded in shallower zones, are quite white or colourless. At between

-60 and 80 fathoms, striping and banding are rarely presented by our

-shells, especially in the northern provinces; from 50 fathoms, shallow

-bands, colours, and patterns, are well marked. _The relation of these

-arrangements of colour to the degree of light penetrating the different

-zones of depth_ is a subject well worthy of minute inquiry.

-

-

-NATURAL WATER-PURIFIERS.

-

-Mr. Warrington kept for a whole year twelve gallons of water in a state

-of admirably balanced purity by the following beautiful action:

-

-  In the tank, or aquarium, were two gold fish, six water-snails, and

-  two or three specimens of that elegant aquatic plant _Valisperia

-  sporalis_, which, before the introduction of the water-snails, by

-  its decayed leaves caused a growth of slimy mucus, and made the

-  water turbid and likely to destroy both plants and fish. But under

-  the improved arrangement the slime, as fast as it was engendered,

-  was consumed by the water-snails, which reproduced it in the shape

-  of young snails, which furnished a succulent food to the fish.

-  Meanwhile the _Valisperia_ plants absorbed the carbonic acid

-  exhaled by the respiration of their companions, fixing the carbon

-  in their growing stems and luxuriant blossoms, and refreshing

-  the oxygen (during sunshine in visible little streams) for the

-  respiration of the snails and the fish. The spectacle of perfect

-  equilibrium thus simply maintained between animal, vegetable, and

-  inorganic activity, was strikingly beautiful; and such means might

-  possibly hereafter be made available on a large scale for keeping

-  tanked water sweet and clean.--_Quarterly Review_, 1850.

-

-

-HOW TO IMITATE SEA-WATER.

-

-The demand for Sea-water to supply the Marine Aquarium--now to be

-seen in so many houses--induced Mr. Gosse to attempt the manufacture

-of Sea-water, more especially as the constituents are well known. He

-accordingly took Scheveitzer’s analysis of Sea-water for his guide. In

-one thousand grains of sea-water taken off Brighton, it gave: water,

-964·744; chloride of sodium, 27·059; chloride of magnesium, 3·666;

-chloride of potassium, 9·755; bromide of magnesium, 0·29; sulphate of

-magnesia, 2·295; sulphate of lime, 1·407; carbonate of lime, 0·033:

-total, 999·998. Omitting the bromide of magnesium, the carbonate of

-lime, and the sulphate of lime, as being very small quantities, the

-component parts were reduced to common salt, 3½ oz.; Epsom salts, ¼

-oz.; chloride of magnesium, 200 grains troy; chloride of potassium,

-40 grains troy; and four quarts of water. Next day the mixture was

-filtered through a sponge into a glass jar, the bottom covered with

-shore-pebbles and fragments of stone and fronds of green sea-weed. A

-coating of green spores was soon deposited on the sides of the glass,

-and bubbles of oxygen were copiously thrown off every day under the

-excitement of the sun’s light. In a week Mr. Gosse put in species of

-_Actinia Bowerbankia_, _Cellularia_, _Serpula_, &c. with some red

-sea-weeds; and the whole throve well.

-

-

-VELOCITY OF IMPRESSIONS TRANSMITTED TO THE BRAIN.

-

-Professor Helmholtz of Königsberg has, by the electro-magnetic

-method,[58] ascertained that the intelligence of an impression

-made upon the ends of the nerves in communication with the skin

-is transmitted to the brain with a velocity of about 195 feet per

-second. Arrived at the brain, about one-tenth of a second passes

-before the will is able to give the command to the nerves that certain

-muscles shall execute a certain motion, varying in persons and times.

-Finally, about 1/100th of a second passes after the receipt of the

-command before the muscle is in activity. In all, therefore, from the

-excitation of the sensitive nerves till the moving of the muscle, 1¼

-to 2/10ths of a second are consumed. Intelligence from the great toe

-arrives about 1/30th of a second later than from the ear or the face.

-

-Thus we see that the differences of time in the nervous impressions,

-which we are accustomed to regard as simultaneous, lie near our

-perception. We are taught by astronomy that, on account of the

-time taken to propagate light, we now see what has occurred in the

-fixed stars years ago; and that, owing to the time required for the

-transmission of sound, we hear after we see is a matter of daily

-experience. Happily the distances to be traversed by our sensuous

-perceptions before they reach the brain are so short that we do

-not observe their influence, and are therefore unprejudiced in our

-practical interest. With an ordinary whale the case is perhaps more

-dubious; for in all probability the animal does not feel a wound near

-its tail until a second after it has been inflicted, and requires

-another second to send the command to the tail to defend itself.

-

-

-PHOTOGRAPHS ON THE RETINA.

-

-The late Rev. Dr. Scoresby explained with much minuteness and skill

-the varying phenomena which presented themselves to him after gazing

-intently for some time on strongly-illuminated objects,--as the sun,

-the moon, a red or orange or yellow wafer on a strongly-contrasted

-ground, or a dark object seen in a bright field. The doctor explained,

-upon removing the eyes from the object, the early appearance of the

-picture or image which had been thus “photographed on the Retina,” with

-the photochromatic changes which the picture underwent while it still

-retained its general form and most strongly-marked features; also, how

-these pictures, when they had almost faded away, could at pleasure, and

-for a considerable time, be renewed by rapidly opening and shutting the

-eyes.

-

-

-DIRECT EXPLORATION OF THE INTERIOR OF THE EYE.

-

-Dr. S. Wood of Cincinnati states, that by means of a small double

-convex lens of short focus held near the eye,--that organ looking

-through it at a candle twelve or fifteen feet distant,--there will be

-perceived a large luminous disc, covered with dark and light spots and

-dark streaks, which, after a momentary confusion, will settle down

-into an unchanging picture, which picture is composed of the organs

-or internal parts of the eye. The eye is thus enabled to view its own

-internal organisation, to have a beautiful exhibition of the vessels of

-the cornea, of the distribution of the lachrymas secretions in the act

-of winking, and to see into the nature and cause of _muscæ volitantes_.

-

-

-NATURE OF THE CANDLE-FLAME.

-

-M. Volger has subjected this Flame to a new analysis.

-

-  He finds that the so-called _flame-bud_, a globular blue flaminule,

-  is first produced at the summit of the wick: this is the result

-  of the combustion of carbonic oxide, hydrogen, and carbon, and is

-  surrounded by a reddish-violet halo, the _veil_. The increased

-  heat now gives rise to the actual flame, which shoots forth from

-  the expanding bud, and is then surrounded at its inferior portion

-  only by the latter. The interior consists of a dark gaseous cone,

-  containing the immediate products of the decomposition of the fatty

-  acids, and surrounded by another dark hollow cone, the _inner

-  cap_. Here we already meet with carbon and hydrogen, which have

-  resulted from the process of decomposition; and we distinguish

-  this cone from the inner one by its yielding soot. The _external

-  cap_ constitutes the most luminous portion of the flame, in which

-  the hydrogen is consumed and the carbon rendered incandescent. The

-  surrounding portion is but slightly luminous, deposits no soot,

-  and in it the carbon and hydrogen are consumed.--_Liebig’s Annual

-  Report._

-

-

-HOW SOON A CORPSE DECAYS.

-

-Mr. Lewis, of the General Board of Health, from his examination of the

-contents of nearly 100 coffins in the vaults and catacombs of London

-churches, concludes that the complete decomposition of a corpse, and

-its resolution into its ultimate elements, takes place in a leaden

-coffin with extreme slowness. In a wooden coffin the remains, with the

-exception of the bones, vanish in from two to five years. This period

-depends upon the quality of the wood, and the free access of air to

-the coffins. But in leaden coffins, 50, 60, 80, and even 100 years

-are required to accomplish this. “I have opened,” says Mr. Lewis, “a

-coffin in which the corpse had been placed for nearly a century; and

-the ammoniacal gas formed dense white fumes when brought in contact

-with hydrochloric-acid gas, and was so powerful that the head could

-not remain in it for more than a few seconds at a time.” To render the

-human body perfectly inert after death, it should be placed in a light

-wooden coffin, in a pervious soil, from five to eight feet deep.

-

-

-MUSKET-BALLS FOUND IN IVORY.

-

-The Ceylon sportsman, in shooting elephants, aims at a spot just above

-the proboscis. If he fires a little too low, the ball passes into the

-tusk-socket, causing great pain to the animal, but not endangering

-its life; and it is immediately surrounded by osteo-dentine. It has

-often been a matter of wonder how such bodies should become completely

-imbedded in the substance of the tusk, sometimes without any visible

-aperture; or how leaden bullets become lodged in the solid centre of a

-very large tusk without having been flattened, as they are found by

-the ivory-turner.

-

-  The explanation is as follows: A musket-ball aimed at the head of

-  an elephant may penetrate the thin bony socket and the thinner

-  ivory parietes of the wide conical pulp-cavity occupying the

-  inserted base of the tusk; if the projectile force be there spent,

-  the ball will gravitate to the opposite and lower side of the

-  pulp-cavity. The pulp becomes inflamed, irregular calcification

-  ensues, and osteo-dentine is formed around the ball. The pulp

-  then resumes its healthy state and functions, and coats the

-  osteo-dentine enclosing the ball, together with the root of the

-  conical cavity into which the mass projects, with layers of normal

-  ivory. The hole formed by the ball is soon replaced, and filled

-  up by osteo-dentine, and coated with cement. Meanwhile, by the

-  continued progress of growth, the enclosed ball is pushed forward

-  to the middle of the solid tusk; or if the elephant be young, the

-  ball may be carried forward by growth and wear of the tusk until

-  its base has become the apex, and become finally exposed and

-  discharged by the continual abrasion to which the apex of the tusk

-  is subjected.--_Professor Owen._

-

-

-NATURE OF THE SUN.

-

-To the article at pp. 59-60 should be added the result obtained by Dr.

-Woods of Parsonstown, and communicated to the _Philosophical Magazine_

-for July 1854. Dr. Woods, from photographic experiment, has no doubt

-that the light from the centre of flame acts more energetically than

-that from the edge on a surface capable of receiving its impression;

-and that light from a luminous solid body acts equally powerfully from

-its centre or its edges: wherefore Dr. Woods concludes that, as the

-sun affects a sensitive plate similarly with flame, it is probable its

-light-producing portion is of a similar nature.

-

-  _Note to_ “IS THE HEAT OF THE SUN DECREASING?” _at page 65_.--Dr.

-  Vaughan of Cincinnati has stated to the British Association:

-  “From a comparison of the relative intensity of solar, lunar,

-  and artificial light, as determined by Euler and Wollaston, it

-  appears that the rays of the sun have an illuminating power

-  equal to that of 14,000 candles at a distance of one foot, or

-  of 3500,000000,000000,000000,000000 candles at a distance of

-  95,000,000 miles. It follows that the amount of light which

-  flows from the solar orb could be scarcely produced by the daily

-  combustion of 200 globes of tallow, each equal to the earth in

-  magnitude. A sphere of combustible matter much larger than the

-  sun itself should be consumed every ten years in maintaining its

-  wonderful brilliancy; and its atmosphere, if pure oxygen, would be

-  expended before a few days in supporting so great a conflagration.

-  An illumination on so vast a scale could be kept up only by the

-  inexhaustible magazine of ether disseminated through space, and

-  ever ready to manifest its luciferous properties on large spheres,

-  whose attraction renders it sufficiently dense for the play of

-  chemical affinity. Accordingly suns derive the power of shedding

-  perpetual light, not from their chemical constitution, but from

-  their immense mass and their superior attractive power.”

-

-

-PLANETOIDS.

-

-  +----------------+---------------+-----------+-----------+-----------+

-  |                |               |           |           |    No.    |

-  |                |               |           |           |discovered |

-  |                |    Date of    |           | Place of  |  by each  |

-  |      Name.     |  Discovery.   |Discoverer.| Discovery.|astronomer.|

-  +----------------+---------------+-----------+-----------+-----------+

-  |Mercury, Mars, }|     Known  }  |           |           |           |

-  |Venus, Jupiter,}|    to the  }  |   ...     |    ...    |    --     |

-  |Earth, Saturn, }|   ancients.}  |           |           |           |

-  |   Uranus       |1781, March 13 |W. Herschel| Bath      |    --     |

-  |   Neptune[59]  |1846, Sept. 23 |Galle      | Berlin    |    --     |

-  | 1 Ceres        |1801, Jan. 1   |Piazzi     | Palermo   |     1     |

-  | 2 Pallas       |1802, March 28 |Olbers     | Bremen    |     1     |

-  | 3 Juno         |1804, Sept. 1  |Harding    | Lilienthal|     1     |

-  | 4 Vesta        |1807, March 29 |Olbers     | Bremen    |     2     |

-  | 5 Astræa       |1845, Dec. 8   |Encke      | Driesen   |     1     |

-  | 6 Hebe         |1847, July 1   |Encke      | Driesen   |     2     |

-  | 7 Iris         |1847, August 13|Hind       | London    |     1     |

-  | 8 Flora        |1847, Oct. 18  |Hind       | London    |     2     |

-  | 9 Metis        |1848, April 25 |Graham     | Markree   |     1     |

-  |10 Hygeia       |1849, April 12 |Gasperis   | Naples    |     1     |

-  |11 Parthenope   |1850, May 11   |Gasperis   | Naples    |     2     |

-  |12 Victoria     |1850, Sept. 13 |Hind       | London    |     3     |

-  |13 Egeria       |1850, Nov. 2   |Gasperis   | Naples    |     3     |

-  |14 Irene        |1851, May 19   |Hind       | London    |     4     |

-  |15 Eunomia      |1851, July 29  |Gasperis   | Naples    |     4     |

-  |16 Psyche       |1852, March 17 |Gasperis   | Naples    |     5     |

-  |17 Thetis       |1852, April 17 |Luther     | Bilk      |     1     |

-  |18 Melpomene    |1852, June 24  |Hind       | London    |     5     |

-  |19 Fortuna      |1852, August 22|Hind       | London    |     6     |

-  |20 Massilia     |1852, Sept. 19 |Gasperis   | Naples    |     6     |

-  |21 Lutetia      |1852, Nov. 15  |Goldschmidt| Paris     |     1     |

-  |22 Calliope     |1852, Nov. 16  |Hind       | London    |     7     |

-  |23 Thalia       |1852, Dec. 15  |Hind       | London    |     8     |

-  |24 Themis       |1853, April 5  |Gasperis   | Naples    |     7     |

-  |25 Phocea       |1853, April 6  |Chacornac  | Marseilles|     1     |

-  |26 Proserpine   |1853, May 5    |Luther     | Bilk      |     2     |

-  |27 Euterpe      |1853, Nov. 8   |Hind       | London    |     9     |

-  |28 Bellona      |1854, March 1  |Luther     | Bilk      |     3     |

-  |29 Amphitrite   |1854, March 1  |Marth      | London    |     1     |

-  |30 Urania       |1854, July 22  |Hind       | London    |    10     |

-  |31 Euphrosyne   |1854, Sept. 1  |Furguson   | Washington|     1     |

-  |32 Pomona       |1854, Oct. 26  |Goldschmidt| Paris     |     2     |

-  |33 Polyhymnia   |1854, Oct. 28  |Chacornac  | Paris     |     2     |

-  |34 Circe        |1855, April 6  |Chacornac  | Paris     |     3     |

-  |35 Leucothea    |1855, April 19 |Luther     | Bilk      |     4     |

-  |36 Atalante     |1855, Oct. 5   |Goldschmidt| Paris     |     3     |

-  |37 Fides        |1855, Oct. 5   |Luther     | Bilk      |     5     |

-  |38 Leda         |1856, Jan. 12  |Chacornac  | Paris     |     4     |

-  |39 Lætitia      |1856, Feb. 8   |Chacornac  | Paris     |     5     |

-  |40 Harmonia     |1856, March 31 |Goldschmidt| Paris     |     4     |

-  |41 Daphne       |1856, May 22   |Goldschmidt| Paris     |     5     |

-  |42 Isis         |1856, May 23   |Pogson     | Oxford    |     1     |

-  |43 Ariadne      |1857, April 15 |Pogson     | Oxford    |     2     |

-  |44 Nysa         |1857, May 27   |Goldschmidt| Paris     |     6     |

-  |45 Eugenia      |1857, June 28  |Goldschmidt| Paris     |     7     |

-  |46 Hastia       |1857, August 16|Pogson     | Oxford    |     3     |

-  |47 Aglaia       |1857, Sept. 15 |Luther     | Bilk      |     6     |

-  |48 Doris        |1857, Sept. 19 |Goldschmidt| Paris     |     8     |

-  |49 Pales        |1857, Sept. 19 |Goldschmidt| Paris     |     9     |

-  |50 Virginia     |1857, Oct. 4   |Furguson   | Washington|     2     |

-  |51 Nemausa      |1858, Jan. 22  |Laurent    | Nismes    |     1     |

-  |52 Europa       |1858, Feb. 6   |Goldschmidt| Paris     |    10     |

-  |53 Calypso      |1858, April 8  |Luther     | Bilk      |     7     |

-  |54 Alexandra    |1858, Sept. 11 |Goldschmidt| Paris     |    11     |

-  |55 (Not named)  |1858, Sept. 11 |Searle     | Albany    |     1     |

-  +----------------+---------------+-----------+-----------+-----------+

-

-

-THE COMET OF DONATI.

-

-While this sheet was passing through the press, the attention of

-astronomers, and of the public generally, was drawn to the fact of

-the above Comet passing (on Oct. 18) within nine millions of miles of

-the planet Venus, or less than 9/100ths of the earth’s distance from

-the Sun. “And (says Mr. Hind, the astronomer), it is obvious that

-if the comet had reached its least distance from the sun a few days

-earlier than it has done, the planet might have passed through it;

-and I am very far from thinking that close proximity to a comet of

-this description would be unattended with danger. The inhabitants of

-Venus will witness a cometary spectacle far superior to that which has

-recently attracted so much attention here, inasmuch as the tail will

-doubtless appear twice as long from that planet as from the earth, and

-the nucleus proportionally more brilliant.”

-

-This Comet was first discovered by Dr. G. B. Donati, astronomer at

-the Museum of Florence, on the evening of the 2d of June, in right

-ascension 141° 18′, and north declination 23° 47′, corresponding to

-a position near the star Leonis. Previous to this date we had no

-knowledge of its existence, and therefore it was not a predicted

-comet; neither is it the one last observed in 1556. At the date of

-discovery it was distant from the earth 228,000,000 of miles, and was

-an excessively faint object in the largest telescopes.

-

-The tail, from October 2 to 16, when the comet was most conspicuous,

-appears to have maintained an average length of at least 40,000,000

-miles, subtending an angle varying from 30° to 40°. The dark line or

-space down the centre, frequently remarked in other great comets,

-was a striking characteristic in that of Donati. The nucleus, though

-small, was intensely brilliant in powerful instruments, and for some

-time bore high magnifiers to much greater advantage than is usual with

-these objects. In several respects this comet resembled the famous

-ones of 1744, 1680, and 1811, particularly as regards the signs of

-violent agitation going on in the vicinity of the nucleus, such as

-the appearance of luminous jets, spiral offshoots, &c., which rapidly

-emanated from the planetary point and as quickly lost themselves in the

-general nebulosity of the head.

-

-On the 5th Oct. the most casual observer had an opportunity of

-satisfying himself as to the accuracy of the mathematical theory of

-the motions of comets in the near approach of the nucleus of Donati’s

-to Arcturus, the principal star in the constellation Bootes. The

-circumstance of the appulse was very nearly as predicted by Mr. Hind.

-

-The comet, according to the investigations by M. Loewy, of the

-Observatory of Vienna, arrived at its least distance from the sun a few

-minutes after eleven o’clock on the morning of the 30th of September;

-its longitude, as seen from the sun at this time, being 36° 13′, and

-its distance from him 55,000,000 miles. The longer diameter of its

-orbit is 184 times that of the earth’s, or 35,100,000,000 miles;

-yet this is considerably less than 1/1000th of the distance of the

-nearest fixed star. As an illustration, let any one take a half-sheet

-of note-paper, and marking a circle with a sixpence in one corner

-of it, describe therein our solar system, drawing the orbits of the

-earth and the inferior planets as small as he can by the aid of a

-magnifying-glass. If the circumference of the sixpence stands for the

-orbit of Neptune, then an oval filling the page will fairly represent

-the orbit of Donati’s comet; and if the paper be laid upon the pavement

-under the west door of St. Paul’s Cathedral, London, the length of that

-edifice will inadequately represent the distance of the nearest fixed

-star. The time of revolution resulting from Mr. Loewy’s calculations

-is 2495 years, which is about 500 years less than that of the comet of

-1811 during the period it was visible from the earth.

-

-That the comet should take more than 2000 years to travel round the

-above page of note-paper is explained by its great diminution of speed

-as it recedes from the sun. At its perihelion it travelled at the rate

-of 127,000 miles an hour, or more than twice as fast as the earth,

-whose motion is about 1000 miles a minute. At its aphelion, however,

-or its greatest distance from the sun, the comet is a very slow body,

-sailing at the rate of 480 miles an hour, or only eight times the

-speed of a railway express. At this pace, were it to travel onward in

-a straight line, the lapse of a million of years would find it still

-travelling half way between our sun and the nearest fixed star.

-

-As this comet last visited us between 2000 and 2495 years since, we

-know that its appearance was at an interesting period of the world’s

-history. It might have terrified the Athenians into accepting the

-bloody code of Draco. It might have announced the destruction of

-Nineveh, or of Babylon, or the capture of Jerusalem by Nebuchadnezzar.

-It might have been seen by the expedition which sailed round Africa

-in the reign of Pharaoh Necho. It might have given interest to the

-foundation of the Pythian games. Within the probable range of its

-last visitation are comprehended the whole of the great events of the

-history of Greece; and among the spectators of the comet may have been

-the so-called sages of Greece and even the prophets of Holy Writ:

-Thales might have attempted to calculate its return, and Jeremiah might

-have tried to read its warning.--_Abridged from a Communication from

-Mr. Hind to the Times, and from a Leader in that Journal._

-

-

-

-

-FOOTNOTES:

-

-

-[1] From a photograph, with figures, to show the relative size of the

-tube aperture.

-

-[2] Weld’s _History of the Royal Society_, vol. ii. p. 188.

-

-[3] Dr. Whewell (_Bridgewater Treatise_, p. 266) well observes, that

-Boyle and Pascal are to hydrostatics what Galileo is to mechanics, and

-Copernicus, Kepler, and Newton are to astronomy.

-

-[4] The Rev. Mr. Turnor recollects that Mr. Jones, the tutor,

-mentioned, in one of his lectures on optics, that the reflecting

-telescope belonging to Newton was then lodged in the observatory over

-the gateway; and Mr. Turnor thinks that he once saw it, with a finder

-affixed to it.

-

-[5] The story of the dog “Diamond” having caused the burning of

-certain papers is laid in London, and in Newton’s later years. In the

-notes to Maude’s _Wenleysdale_, a person then living (1780) relates,

-that Sir Isaac being called out of his study to a contiguous room, a

-little dog, called Diamond, the constant but incurious attendant of

-his master’s researches, happened to be left among the papers, and

-by a fatality not to be retrieved, as it was in the latter part of

-Sir Isaac’s days, threw down a lighted candle, which consumed the

-almost finished labour of some years. Sir Isaac returning too late

-but to behold the dreadful wreck, rebuked the author of it with an

-exclamation (_ad sidera palmas_), “O Diamond! Diamond! thou little

-knowest the mischief done!” without adding a single stripe. M. Biot

-gives this fiction as a true story, which happened some years after

-the publication of the _Principia_; and he characterises the accident

-as having deprived the sciences forever of the fruit of so much of

-Newton’s labours.--Brewster’s _Life_, vol. ii. p. 139, note. Dr. Newton

-remarks, that Sir Isaac never had any communion with dogs or cats; and

-Sir David Brewster adds, that the view which M. Biot has taken of the

-idle story of the dog Diamond, charged with fire-raising among Newton’s

-manuscripts, and of the influence of this accident upon the mind of

-their author, is utterly incomprehensible. The fiction, however, was

-turned to account in giving colour to M. Biot’s misrepresentation.

-

-[6] Bohn’s edition.

-

-[7] When at Pisa, many years since, Captain Basil Hall investigated

-the origin and divergence of the tower from the perpendicular, and

-established completely to his own satisfaction that it had been built

-from top to bottom originally just as it now stands. His reasons for

-thinking so were, that the line of the tower, on that side towards

-which it leans, has not the same curvature as the line on the opposite,

-or what may be called the upper side. If the tower had been built

-upright, and then been made to incline over, the line of the wall on

-that side towards which the inclination was given would be more or less

-concave in that direction, owing to the nodding or “swagging over” of

-the top, by the simple action of gravity acting on a very tall mass

-of masonry, which is more or less elastic when placed in a sloping

-position. But the contrary is the fact; for the line of wall on the

-side towards which the tower leans is decidedly more convex than the

-opposite side. Captain Hall had therefore no doubt whatever that the

-architect, in rearing his successive courses of stones, gained or

-stole a little at each layer, so as to render his work less and less

-overhanging as he went up; and thus, without betraying what he was

-about, really gained stability.--See _Patchwork_.

-

-[8] Lord Bacon proposed that, in order to determine whether the gravity

-of the earth arises from the gravity of its parts, a clock-pendulum

-should be swung in a mine, as was recently done at Harton colliery by

-the Astronomer-Royal.

-

-When, in 1812, Ampère noted the phenomena of the pendulum, and showed

-that its movement was produced only when the eye of the observer was

-fixed on the instrument, and endeavoured to prove thereby that the

-motion was due to a play of the muscles, some members of the French

-Academy objected to the consideration of a subject connected to such an

-extent with superstition.

-

-[9] This curious fact was first recorded by Pepys, in his _Diary_,

-under the date 31st of July 1665.

-

-[10] The result of these experiments for ascertaining the variation

-of the gravity at great depths, has proved beyond doubt that the

-attraction of gravitation is increased at the depth of 1250 feet by

-1/19000 part.

-

-[11] See the account of Mr. Baily’s researches (with two illustrations)

-in _Things not generally Known_, p. vii., and “Weight of the Earth,” p.

-16.

-

-[12] Fizeau gives his result in leagues, reckoning twenty-five to the

-equatorial degree. He estimates the velocity of light at 70,000 such

-leagues, or about 210,000 miles in the second.

-

-[13] See _Things not generally Known_, p. 88.

-

-[14] Some time before the first announcement of the discovery of

-sun-painting, the following extract from Sir John Herschel’s _Treatise

-on Light_, in the _Encyclopædia Metropolitana_, appeared in a popular

-work entitled _Parlour Magic_: “Strain a piece of paper or linen upon

-a wooden frame, and sponge it over with a solution of nitrate of

-silver in water; place it behind a painting upon glass, or a stained

-window-pane, and the light, traversing the painting or figures, will

-produce a copy of it upon the prepared paper or linen; those parts in

-which the rays were least intercepted being the shadows of the picture.”

-

-[15] In his book on Colours, Mr. Doyle informs us that divers, if not

-all, essential oils, as also spirits of wine, when shaken, “have a

-good store of bubbles, which appear adorned with various and lively

-colours.” He mentions also that bubbles of soap and turpentine exhibit

-the same colours, which “vary according to the incidence of the sight

-and the position of the eye;” and he had seen a glass-blower blow

-bubbles of glass which burst, and displayed “the varying colours of the

-rainbow, which were exceedingly vivid.”

-

-[16] The original idea is even attributed to Copernicus. M. Blundevile,

-in his _Treatise on Cosmography_, 1594, has the following passage,

-perhaps the most distinct recognition of authority in our language:

-“How prooue (prove) you that there is but one world? By the authoritie

-of Aristotle, who saieth that if there were any other world out of

-this, then the earth of that world would mooue (move) towards the

-centre of this world,” &c.

-

-Sir Isaac Newton, in a conversation with Conduitt, said he took “all

-the planets to be composed of the same matter with the earth, viz.

-earth, water, and stone, but variously concocted.”

-

-[17] Sir William Herschel ascertained that our solar system is

-advancing towards the constellation Hercules, or more accurately to a

-point in space whose right ascension is 245° 52′ 30″, and north polar

-distance 40° 22′; and that the quantity of this motion is such, that to

-an astronomer placed in Sirius, our sun would appear to describe an arc

-of little more than _a second_ every year.--_North-British Review_, No.

-3.

-

-[18] See M. Arago’s researches upon this interesting subject, in

-_Things not generally Known_, p. 4.

-

-[19] This eloquent advocacy of the doctrine of “More Worlds than One”

-(referred to at p. 51) is from the author’s valuable _Outlines of

-Astronomy_.

-

-[20] Professor Challis, of the Cambridge Observatory, directing the

-Northumberland telescope of that institution to the place assigned by

-Mr. Adams’s calculations and its vicinity on the 4th and 12th of August

-1846, saw the planet on both those days, and noted its place (among

-those of other stars) for re-observation. He, however, postponed the

-_comparison_ of the places observed, and not possessing Dr. Bremiker’s

-chart (which would at once have indicated the presence of an unmapped

-star), remained in ignorance of the planet’s existence as a visible

-object till the announcement of such by Dr. Galle.

-

-[21] For several interesting details of Comets, see “Destruction of the

-World by a Comet,” in _Popular Errors Explained and Illustrated_, new

-edit. pp. 165-168.

-

-[22] The letters of Sir Isaac Newton to Dr. Bentley, containing

-suggestions for the Boyle Lectures, possess a peculiar interest in the

-present day. “They show” (says Sir David Brewster) “that the _nebular

-hypothesis_, the dull and dangerous heresy of the age, is incompatible

-with the established laws of the material universe, and that an

-omnipotent arm was required to give the planets their positions and

-motions in space, and a presiding intelligence to assign to them the

-different functions they had to perform.”--_Life of Newton_, vol. ii.

-

-[23] The constitution of the nebulæ in the constellation of Orion has

-been resolved by this instrument; and by its aid the stars of which it

-is composed burst upon the sight of man for the first time.

-

-[24] Several specimens of Meteoric Iron are to be seen in the

-Mineralogical Collection in the British Museum.

-

-[25] _Life of Sir Isaac Newton_, vol. i. p. 62.

-

-[26] _Description of the Monster Telescope_, by Thomas Woods, M.D. 4th

-edit. 1851.

-

-[27] This instrument also discovered a multitude of new objects in the

-moon; as a mountainous tract near Ptolemy, every ridge of which is

-dotted with extremely minute craters, and two black parallel stripes in

-the bottom of Aristarchus. Dr. Robinson, in his address to the British

-Association in 1843, stated that in this telescope a building the size

-of the Court-house at Cork would be easily visible on the lunar surface.

-

-[28] Mr. Hopkins supports his Glacial Theory by regarding the _Waves

-of Translation_, investigated by Mr. Scott Russell, as furnishing

-a sufficient moving power for the transportation of large rounded

-boulders, and the formation of drifted gravel. When these waves of

-translation are produced by the sudden elevation of the surface of

-the sea, the whole mass of water from the surface to the bottom of

-the ocean moves onward, and becomes a mechanical agent of enormous

-power. Following up this view, Mr. Hopkins has shown that “elevations

-of continental masses of only 50 feet each, and from beneath an ocean

-having a depth of between 300 and 400 feet, would cause the most

-powerful divergent waves, which could transport large boulders to great

-distances.”

-

-[29] It is scarcely too much to say, that from the collection of

-specimens of building-stones made upon this occasion, and first

-deposited in a house in Craig’s Court, Charing Cross, originated,

-upon the suggestion of Sir Henry Delabeche, the magnificent Museum of

-Practical Geology in Jermyn Street; one of the most eminently practical

-institutions of this scientific age.

-

-[30] Mr. R. Mallet, F.R.S., and his son Dr. Mallet, have constructed a

-seismographic map of the world, with seismic bands in their position

-and relative intensity; and small black discs to denote volcanoes,

-femaroles, and soltataras, and shades indicating the areas of

-subsidence.

-

-[31] It has been computed that the shock of this earthquake pervaded

-an area of 700,000 miles, or the twelfth part of the circumference of

-the globe. This dreadful shock lasted only five minutes; and nearly

-the whole of the population being within the churches (on the feast of

-All Saints), no less than 30,000 persons perished by the fall of these

-edifices.--See _Daubeny on Volcanoes_; _Translator’s note, Humboldt’s

-Cosmos_.

-

-[32] Mr. Murray mentions, on the authority of the Rev. Dr. Robinson,

-of the Observatory at Armagh, that a rough diamond with a red tint,

-and valued by Mr. Rundell at twenty guineas, was found in Ireland,

-many years since, in the bed of a brook flowing through the county of

-Fermanagh.

-

-[33] The use of malachite in ornamental work is very extensive in

-Russia. Thus, to the Great Exhibition of 1851 were sent a pair of

-folding-doors veneered with malachite, 13 feet high, valued at

-6000_l._; malachite cases and pedestals from 1500_l._ to 3000_l._

-a-piece, malachite tables 400_l._, and chairs 150_l._ each.

-

-[34] Longfellow has written some pleasing lines on “The Fiftieth

-Birthday of M. Agassiz. May 28, 1857,” appended to “The Courtship of

-Miles Standish,” 1858.

-

-[35] The _sloth_ only deserves its name when it is obliged to attempt

-to proceed along the ground; when it has any thing which it can lay

-hold of it is agile enough.

-

-[36] Dr. A. Thomson has communicated to _Jameson’s Journal_, No. 112,

-a Description of the Caves in the North Island, with some general

-observations on this genus of birds. He concludes them to have been

-indolent, dull, and stupid; to have lived chiefly on vegetable food in

-mountain fastnesses and secluded caverns.

-

-In the picture-gallery at Drayton Manor, the seat of Sir Robert Peel,

-hangs a portrait of Professor Owen, and in his hand is depicted the

-tibia of a Moa.

-

-[37] According to the law of correlation, so much insisted on by

-Cuvier, a superior character implies the existence of its inferiors,

-and that too in definite proportions and constant connections; so

-that we need only the assurance of one character, to be able to

-reconstruct the whole animal. The triumph of this system is seen in

-the reconstruction of extinct animals, as in the above case of the

-Dinornis, accomplished by Professor Owen.

-

-[38] Not only at London, but at Paris, Vienna, Berlin, Turin. St.

-Petersburg, and almost every other capital in Europe; at Liege, Caen,

-Montpellier, Toulouse, and several other large towns,--wherever,

-in fact, there are not great local obstacles,--the tendency of the

-wealthier inhabitants to group themselves to the west is as strongly

-marked as in the British metropolis. At Pompeii, and other ancient

-towns, the same thing maybe noticed; and where the local configuration

-of the town necessitates an increase in a different direction, the

-moment the obstacle ceases houses spread towards the west.

-

-[39] By far the most complete set of experiments on the Radiation

-of Heat from the Earth’s Surface at Night which have been published

-since Dr. Wells’s Memoir _On Dew_, are those of Mr. Glaisher, F.R.S.,

-_Philos. Trans._ for 1847.

-

-[40] The author is largely indebted for the illustrations in this new

-field of research to Lieutenant Maury’s valuable work, _The Physical

-Geography of the Sea_. Sixth edition. Harper, New York; Low, Son, and

-Co., London.

-

-[41] It is the chloride of magnesia which gives that damp sticky

-feeling to the clothes of sailors that are washed or wetted with salt

-water.

-

-[42] This fraction rests on the assumption that the dilatation of the

-substances of which the earth is composed is equal to that of glass,

-that is to say, 1/18000 for 1°. Regarding this hypothesis, see Arago,

-in the _Annuaire_ for 1834, pp. 177-190.

-

-[43] Electricity, traversing excessively rarefied air or vapours,

-gives out light, and doubtless also heat. May not a continual current

-of electric matter be constantly circulating in the sun’s immediate

-neighbourhood, or traversing the planetary spaces, and exerting in the

-upper regions of its atmosphere those phenomena of which, on however

-diminutive a scale, we have yet an unequivocal manifestation in our

-Aurora Borealis?

-

-[44] Could we by mechanical pressure force water into a solid state, an

-immense quantity of heat would be set free.

-

-[45] See Mr. Hunt’s popular work, _The Poetry of Science; or, Studies

-of Physical Phenomena of Nature_. Third edition, revised and enlarged.

-Bohn, 1854.

-

-[46] Canton was the first who in England verified Dr. Franklin’s idea

-of the similarity of lightning and the electric fluid, July 1752.

-

-[47] This is mentioned in _Procli Diadochi Paraphrasis Ptolem._, 1635.

-(Delambre, _Hist. de l’Astronomie ancienne_.)

-

-[48] The first Variation-Compass was constructed, before 1525, by an

-ingenious apothecary of Seville, Felisse Guillen. So earnest were

-the endeavours to learn more exactly the direction of the curves of

-magnetic declination, that in 1585 Juan Jayme sailed with Francisco

-Gali from Manilla to Acapulco, for the sole purpose of trying in the

-Pacific a declination instrument which he had invented.--_Humboldt._

-

-[49] Gilbert was surgeon to Queen Elizabeth and James I., and died

-in 1603. Whewell justly assigns him an important place among the

-“practical reformers of the physical sciences.” He adopted the

-Copernican doctrine, which Lord Bacon’s inferior aptitude for physical

-research led him to reject.

-

-[50] This illustration, it will be seen, does not literally correspond

-with the details which precede it.

-

-[51] Mr. Crosse gave to the meeting a general invitation to Fyne Court;

-one of the first to accept which was Sir Richard Phillips, who, on

-his return to Brighton, described in a very attractive manner, at the

-Sussex Institution, Mr. Crosse’s experiments and apparatus; a report of

-which being communicated to the _Brighton Herald_, was quoted in the

-_Literary Gazette_, and thence copied generally into the newspapers of

-the day.

-

-[52] These experiments were performed at the expense of the Royal

-Society, and cost 10_l._ 5_s._ 6_d._ In the Paper detailing the

-experiments, printed in the 45th volume of the _Philosophical

-Transactions_, occurs the first mention of Dr. Franklin’s name, and of

-his theory of positive and negative electricity.--_Weld’s Hist. Royal

-Soc._ vol. i. p. 467.

-

-[53] In this year Andrew Crosse said: “I prophesy that by means of

-the electric agency we shall be enabled to communicate our thoughts

-instantaneously with the uttermost parts of the earth.”

-

-[54] To which paper the writer is indebted for many of these details.

-

-[55] These illustrations have been in the main selected and abridged

-from papers in the _Companion to the Almanac_, 1858, and the _Penny

-Cyclopædia_, 2d supp.

-

-[56] Newton was, however, much pestered with inquirers; and a

-Correspondent of the _Gentleman’s Magazine_, in 1784, relates that he

-once had a transient view of a Ms. in Pope’s handwriting, in which

-he read a verified anecdote relating to the above period. Sir Isaac

-being often interrupted by ignorant pretenders to the discovery of

-the longitude, ordered his porter to inquire of every stranger who

-desired admission whether he came about the longitude, and to exclude

-such as answered in the affirmative. Two lines in Pope’s Ms., as the

-Correspondent recollects, ran thus:

-

-    “‘Is it about the longitude you come?’

-    The porter asks: ‘Sir Isaac’s not at home.’”

-

-[57] In trying the merits of Harrison’s chronometers, Dr. Maskelyne

-acquired that knowledge of the wants of nautical astronomy which

-afterwards led to the formation of the Nautical Almanac.

-

-[58] A slight electric shock is given to a man at a certain portion of

-the skin; and he is directed the moment he feels the stroke to make a

-certain motion, as quickly as he possibly can, with the hands or with

-the teeth, by which the time-measuring current is interrupted.

-

-[59] Through the calculations of M. Le Verrier.

-

-

-

-

-GENERAL INDEX

-

-

-  Abodes of the Blest, 58.

-

-  Acarus of Crosse and Weeks, 218.

-

-  Accuracy of Chinese Observers, 159.

-

-  Adamant, What was it?, 123.

-

-  Aeronautic Voyage, Remarkable, 169.

-

-  Agassiz, Discoveries of, 127.

-

-  Air, Weight of, 14.

-

-  All the World in Motion, 11.

-

-  Alluvial Land of Egypt, 110.

-

-  Ancient World, Science of the, 1.

-

-  Animals in Geological Times, 128.

-

-  Anticipations of the Electric Telegraph, 220-224.

-

-  Arago on Protection from Storms, 159.

-

-  Arctic Climate, Phenomena of, 162.

-

-  Arctic Explorations, Rae’s, 162.

-

-  Arctic Regions, Scenery and Life of, 180.

-

-  Arctic Temperature, 161.

-

-  Armagh Observatory Level, Change of, 144.

-

-  Artesian Fire-Springs, 118.

-

-  Artesian Well of Grenelle, 114.

-

-  Astronomer, Peasant, 101.

-

-  Astronomer’s Dream verified, 88.

-

-  Astronomers, Triad of Contemporary, 100.

-

-  Astronomical Observations, Nicety of, 102.

-

-  Astronomy and Dates on Monuments, 55.

-

-  Astronomy and Geology, Identity of, 104.

-

-  Astronomy, Great Truths of, 54.

-

-  Atheism, Folly of, 3.

-

-  Atlantic, Basin of the, 171.

-

-  Atlantic, Gales of the, 171.

-

-  Atlantic Telegraph, the, 226-228.

-

-  Atmosphere, Colours of the, 147.

-

-  Atmosphere compared to a Steam-engine, 152.

-

-  Atmosphere, Height of, 147.

-

-  Atmosphere, the, 146.

-

-  Atmosphere, the purest, 150.

-

-  Atmosphere, Universality of the, 147.

-

-  Atmosphere weighed by Pascal, 148.

-

-  Atoms of Elementary Bodies, 13.

-

-  Atoms, the World of, 13.

-

-  Aurora Borealis, Halley’s hypothesis of, 198.

-

-  Aurora Borealis, Splendour of the, 165.

-

-  Australian Cavern, Inmates of, 137.

-

-  Australian Pouch-Lion, 137.

-

-  Axis of Rotation, the, 11.

-

-

-  Barometer, Gigantic, 151.

-

-  Barometric Measurement, 151.

-

-  Batteries, Minute and Vast, 204.

-

-  Birds, Gigantic, of New Zealand, Extinct, 139.

-

-  “Black Waters, the,” 182.

-

-  Bodies, Bright, the Smallest, 31.

-

-  Bodies, Compression of, 12.

-

-  Bodies, Fall of, 16.

-

-  Bottles and Currents at Sea, 172.

-

-  Boulders, How transported to Great Heights, 105.

-

-  Boyle on Colours, 49.

-

-  Boyle, Researches of, 6.

-

-  Brain, Impressions transmitted to, 235.

-

-  Buckland, Dr., his Geological Labours, 127.

-

-  Building-Stone, Wear of, 108.

-

-  Burnet’s Theory of the Earth, 125.

-

-  Bust, Magic, 36.

-

-

-  Candle-flame, Nature of, 237.

-

-  Canton’s Artificial Magnets, 196.

-

-  Carnivora of Britain, Extinct, 132.

-

-  Carnivores, Monster, of France, 138.

-

-  Cataract, Great, in India, 183.

-

-  Cat, Can it see in the Dark?, 51.

-

-  Caves of New Zealand and its Gigantic Birds, 140.

-

-  Cave Tiger or Lion of Britain, 133.

-

-  Central Heat, Theory of, 116.

-

-  Chabert, “the Fire King,” 192.

-

-  Chalk Formation, the, 108.

-

-  Changes on the Earth’s Surface, 142.

-

-  Chantrey, Heat-Experiments by, 192.

-

-  Children’s powerful Battery, 204.

-

-  Chinese, the, and the Magnetic Needle, 194.

-

-  Chronometers, Marine, How rated at Greenwich Observatory, 229.

-

-  Climate, finest in the World, 149.

-

-  Climate, Variations of, 148.

-

-  Climates, Average, 149.

-

-  Clock, How to make Electric, 212.

-

-  Cloud-ring, the Equatorial, 156.

-

-  Clouds, Fertilisation of, 151.

-

-  Coal, Torbane-Hill, 123.

-

-  Coal, What is it?, 123.

-

-  Cold in Hudson’s Bay, 160.

-

-  Colour of a Body, and its Magnetic Properties, 197.

-

-  Colours and Tints, Chevreul on, 37.

-

-  Colours most frequently hit in Battle, 36.

-

-  Comet, the, of Donati, 240, 241.

-

-  Comet, Great, of 1843, 84.

-

-  Comets, Magnitude of, 84.

-

-  Comets visible in Sunshine, 84.

-

-  Computation, Power of, 10.

-

-  Coney of Scripture, 137.

-

-  Conic Sections, 10.

-

-  Continent Outlines not fixed, 145.

-

-  Corpse, How soon it decays, 237.

-

-  “Cosmos, Science of the,” 10.

-

-  Crosse, Andrew, his Artificial Crystals and Minerals, 216-219.

-

-  Crosse Mite, the, 218.

-

-  Crystallisation, Reproductive, 26.

-

-  Crystallisation, Theory of, 24.

-

-  Crystallisation, Visible, 25.

-

-  Crystals, Immense, 24.

-

-  “Crystal Vault of Heaven,” 55.

-

-

-  Davy, Sir Humphry, obtains Heat from Ice, 190.

-

-  Davy’s great Battery at the Royal Institution, 204.

-

-  Day, Length of, and Heat of the Earth, 186.

-

-  Day’s Length at the Poles, 65.

-

-  Declination of the Needle, 197.

-

-  Descartes’ Labours in Physics, 9.

-

-  Desert, Intense Heat and Cold of the, 163.

-

-  Dew-drop, Beauty of the, 157.

-

-  Dew-fall in one year, 157.

-

-  Dew graduated to supply Vegetation, 157.

-

-  Diamond, Geological Age of, 122.

-

-  Diamond Lenses for Microscopes, 40.

-

-  “Diamond,” Newton’s Dog, 8.

-

-  Dinornis elephantopus, the, 139, 140.

-

-  Dinotherium, or Terrible Beast, the, 136.

-

-  Diorama, Illusion of the, 37.

-

-

-  Earth and Man compared, 22.

-

-  Earth, Figure of the, 21.

-

-  Earth, Mass and Density of, 21.

-

-  Earth’s Annual Motion, 12.

-

-  Earth’s Magnitude, to ascertain, 21.

-

-  Earth’s Surface, Mean Temperature of, 23.

-

-  Earth’s Temperature, Interior, 116.

-

-  Earth’s Temperature Stationary, 23.

-

-  Earth, the, a Magnet, 197.

-

-  Earthquake, the Great Lisbon, 121.

-

-  Earthquakes and the Moon, 121.

-

-  Earthquakes, Rumblings of, 120.

-

-  Earthquake-Shock, How to measure, 120.

-

-  Earth-Waves, 119.

-

-  Eclipses, Cause of, 74.

-

-  Egypt, Alluvial Land of, 110.

-

-  Electric Girdle for the Earth, 224.

-

-  Electric Incandescence of Charcoal Points, 204.

-

-  Electric Knowledge, Germs of, 207.

-

-  Electric Light, Velocity of, 209.

-

-  Electric Messages, Time lost in, 225.

-

-  Electric Paper, 209.

-

-  Electric Spark, Duration of, 209.

-

-  Electric Telegraph, Anticipations of the, 220-224.

-

-  Electric Telegraph, Consumption of, 224.

-

-  Electric Telegraph in Astronomy and Longitude, 225.

-

-  Electric Telegraph and Lightning, 226.

-

-  Electric and Magnetic Attraction, Identity of, 210.

-

-  Electrical Kite, Franklin’s, 213.

-

-  Electricity and Temperature, 208.

-

-  Electricity in Brewing, 209.

-

-  Electricity, Vast Arrangement of, 208.

-

-  Electricity, Water decomposed by, 208.

-

-  Electricities, the Two, 214.

-

-  Electro-magnetic Clock, Wheatstone’s, 211.

-

-  Electro-magnetic Engine, Theory of, 210.

-

-  Electro-magnets, Horse-shoe, 199.

-

-  Electro-telegraphic Message to the Stars, 226.

-

-  Elephant and Tortoise of India, 135.

-

-  End of our System, 92.

-

-  England in the Eocene Period, 129.

-

-  English Channel, Probable Origin of, 105.

-

-  Eocene Period, the, 129.

-

-  Equatorial Cloud-ring, 156.

-

-  “Equatorial Doldrums,” 156.

-

-  Error upon Error, 185.

-

-  Exhilaration in ascending Mountains, 163.

-

-  Eye and Brain seen through a Microscope, 41.

-

-  Eye, interior, Exploration of, 236.

-

-

-  Fall of Bodies, Rate of, 16.

-

-  Falls, Height of, 16.

-

-  Faraday, Genius and Character of, 193.

-

-  Faraday’s Electrical Illustrations, 214.

-

-  “Father of English Geology, the,” 126.

-

-  Fertilisation of Clouds, 151.

-

-  Fire, Perpetual, 117.

-

-  Fire-balls and Shooting Stars, 89.

-

-  Fire-Springs, Artesian, 118.

-

-  Fishes, the most Ancient, 132.

-

-  Flying Dragon, the, 130.

-

-  Force neither created nor destroyed, 18.

-

-  Force of Running Water, 114.

-

-  Fossil Human Bones, 131.

-

-  Fossil Meteoric Stones, none, 92.

-

-  Fossil Rose, none, 142.

-

-  Foucault’s Pendulum Experiments, 22.

-

-  Franklin’s Electrical Kite, 213.

-

-  Freezing Cavern in Russia, 115.

-

-  Fresh Water in Mid-Ocean, 182.

-

-

-  Galilean Telescope, the, 93.

-

-  Galileo, What he first saw with the Telescope, 93.

-

-  Galvani and Volta, 205.

-

-  Galvanic Effects, Familiar, 203.

-

-  Galvanic Waves on the same Wire, Non-interference of, 225.

-

-  “Gauging the Heavens,” 58.

-

-  Genius, Relics of, 5.

-

-  Geology and Astronomy, Identity of, 104.

-

-  Geology of England, 105.

-

-  Geological Time, 143.

-

-  George III., His patronage of Herschel, 95.

-

-  Gilbert on Magnetic and Electric forces, 201.

-

-  Glacial Theory, by Hopkins, 105.

-

-  Glaciers, Antiquity of, 109.

-

-  Glaciers, Phenomena of, Illustrated, 108.

-

-  Glass, Benefits of, to Man, 92.

-

-  Glass broken by Sand, 26.

-

-  Glyptodon, the, 137.

-

-  Gold, Lumps of, in Siberia, 124.

-

-  Greenwich Observatory, Chronometers rated at, 229-232.

-

-  Grotto del Cane, the, 112.

-

-  Gulf-Stream and the Temperature of London, 115.

-

-  Gunpowder-Magazines, Danger to, 216.

-

-  Gymnotus and the Voltaic Battery, 206.

-

-  Gyroscope, Foucault’s, 22.

-

-

-  Hail and Storms, Protection against, 159.

-

-  Hail-storm, Terrific, 160.

-

-  Hair, Microscopical Examination of, 41.

-

-  Harrison’s Prize Chronometers, 229-232.

-

-  Heat and Evaporation, 188.

-

-  Heat and Mechanical Power, 188.

-

-  Heat by Friction, 189.

-

-  Heat, Distinctions of, 187.

-

-  Heat, Expenditure of, by the Sun, 186.

-

-  Heat from Gas-lighting, 189.

-

-  Heat from Wood and Ice, 190.

-

-  Heat, Intense, Protection from, 191, 192.

-

-  Heat, Latent, 187.

-

-  Heat of Mines, 188.

-

-  Heat, Nice Measurement of, 186.

-

-  Heat, Origin of, in our System, 87.

-

-  Heat passing through Glass, 189.

-

-  Heat, Repulsion by, 191.

-

-  Heated Metals, Vibration of, 188.

-

-  Heavy Persons, Lifting, 17.

-

-  Heights and Distances, to Calculate, 19.

-

-  Herschel’s Telescopes at Slough, 95.

-

-  Highton’s Minute Battery, 204.

-

-  Hippopotamus of Britain, 135.

-

-  “Horse Latitudes, the,” 173.

-

-  Horse, Three-hoofed, 138.

-

-  Hour-glass, Sand in the, 20.

-

-

-  Ice, Heat from, 190.

-

-  Ice, Warming with, 190.

-

-  Icebergs of the Polar Seas, 180.

-

-  Iguanodon, Food of the, 129.

-

-  Improvement, Perpetuity of, 5.

-

-  Inertia Illustrated, 14.

-

-

-  Jerusalem, Temple of, How protected from Lightning, 167.

-

-  Jew’s Harp, Theory of the, 29.

-

-  Jupiter’s Satellites, Discovery of, 80.

-

-

-  Kaleidoscope, Sir David Brewster’s, 43.

-

-  Kaleidoscope, the, thought to be anticipated, 43.

-

-  Kircher’s “Magnetism,” 194.

-

-

-  Leaning Tower, Stability of, 15.

-

-  Level, Curious Change of, 144.

-

-  Leyden Jar, Origin of the, 216.

-

-  Lifting Heavy Persons, 17.

-

-  Light, Action of, on Muscular Fibres, 34.

-

-  Light, Apparatus for Measuring, 32.

-

-  Light from Buttons, 36.

-

-  Light, Effect of, on the Magnet, 198.

-

-  Light from Fungus, 36.

-

-  Light from the Juice of a Plant, 35.

-

-  Light, Importance of, 34.

-

-  Light, Minuteness of, 34.

-

-  Light Nights, 35.

-

-  Light, Polarisation of, 33.

-

-  Light, Solar and Artificial Compared, 29.

-

-  Light, Source of, 29.

-

-  Light, Undulatory Scale of, 30.

-

-  Light, Velocity of, 31.

-

-  Light, Velocity of, Measured by Fizeau, 32.

-

-  Light from Quartz, 51.

-

-  Lightning-Conductor, Ancient, 167.

-

-  Lightning-Conductors, Service of, 166.

-

-  Lightning Experiment, Fatal, 214.

-

-  Lightning, Photographic Effects of, 45.

-

-  Lightning produced by Rain, 166.

-

-  Lightning, Sheet, What is it?, 165.

-

-  Lightning, Varieties of, 165.

-

-  Lightning, Various Effects of, 168.

-

-  Log, Invention of the, 173.

-

-  London Monument used as an Observatory, 103.

-

-

-  “Maestricht Saurian Fossil,” the, 141.

-

-  Magnet, Power of a, 195.

-

-  Magnets, Artificial, How made, 195.

-

-  Magnetic Clock and Watch, 211.

-

-  Magnetic Electricity discovered, 199.

-

-  Magnetic Hypotheses, 193.

-

-  Magnetic Needle and the Chinese, 194.

-

-  Magnetic Poles, North and South, 201.

-

-  Magnetic Storms, 202.

-

-  “Magnetism,” Kircher’s, 194.

-

-  Malachite, How formed, 124.

-

-  Mammalia in Secondary Rocks, 130.

-

-  Mammoth of the British Isles, 133.

-

-  Mammoth, Remains of the, 134.

-

-  Mars, the Planet, Is it inhabited?, 82.

-

-  Mastodon coexistent with Man, 135.

-

-  Matter, Divisibility of, 14.

-

-  Maury’s Physical Geography of the Sea, 170.

-

-  Mediterranean, Depth of, 176.

-

-  Megatherium, Habits of the, 135.

-

-  Mercury, the Planet, Temperature of, 82.

-

-  Mer de Glace, Flow of the, 110.

-

-  Meteoric Stones, no Fossil, 92.

-

-  Meteorites, Immense, 91.

-

-  Meteorites from the Moon, 89.

-

-  Meteors, Vast Shower of, 91.

-

-  Microscope, the Eye, Brain, and Hair seen by, 41.

-

-  Microscope, Fish-eye, How to make, 40.

-

-  Microscope, Invention of the, 39.

-

-  Microscope for Mineralogists, 42.

-

-  Microscope and the Sea, 42.

-

-  Microscopes, Diamond Lenses for, 40.

-

-  Microscopes, Leuwenhoeck’s, 40.

-

-  Microscopic Writing, 42.

-

-  Milky Way, the, Unfathomable, 85.

-

-  Mineralogy and Geometry, Union of, 25.

-

-  Mirror, Magic, How to make, 43.

-

-  Moon’s Attraction, the, 73.

-

-  Moon, Has it an Atmosphere?, 69.

-

-  Moon, Life in the, 71.

-

-  Moon, Light of the, 70.

-

-  Moon, Mountains in, 72.

-

-  Moon, Measuring the Earth by, 74.

-

-  Moon seen through the Rosse Telescope, 72.

-

-  Moon, Scenery of, 71.

-

-  Moon and Weather, the, 73.

-

-  Moonlight, Heat of, 70.

-

-  “More Worlds than One,” 56, 57.

-

-  Mountain-chains, Elevation of, 107.

-

-  Music of the Spheres, 55.

-

-  Musket-balls found in Ivory, 237.

-

-

-  Natural and Supernatural, the, 6.

-

-  Nautical Almanac, Errors in, 185.

-

-  Nebulæ, Distances of, 85.

-

-  Nebular Hypothesis, the, 86.

-

-  Neptune, the Planet, Discovery of, 83.

-

-  Newton, Sir Isaac, his “Apple-tree,” 8.

-

-  Newton upon Burnet’s Theory of the Earth, 125.

-

-  Newton’s Dog “Diamond,” 8.

-

-  Newton’s first Reflecting Telescope, 94.

-

-  Newton’s “Principia,” 9.

-

-  Newton’s Rooms at Cambridge, 7.

-

-  Newton’s Scale of Colours, 49.

-

-  Newton’s Soap-bubble Experiments, 49, 50.

-

-  New Zealand, Extinct Birds of, 139.

-

-  Niagara, the Roar of, 28.

-

-  Nineveh, Rock-crystal Lens found at, 39.

-

-  Non-conducting Bodies, 215.

-

-  Nothing Lost in the Material World, 18.

-

-

-  Objects really of no Colour, 37.

-

-  Objects, Visibility of, 30.

-

-  Observation, the Art of, 3.

-

-  Observatory, Lacaille’s, 101.

-

-  Observatory, the London Monument, 103.

-

-  Observatory, Shirburn Castle, 101.

-

-  Ocean and Air, Depths of unknown, 174.

-

-  Ocean Highways, 184.

-

-  Ocean, Stability of the, 12.

-

-  Ocean, Transparency of the, 171.

-

-  “Oldest piece of Wood upon the Earth,” 142.

-

-  Optical Effects, Curious, at the Cape, 38.

-

-  Optical Instruments, Late Invention of, 100.

-

-  Oxford and Cambridge, Science at, 1.

-

-

-  Pascal, How he weighed the Atmosphere, 148.

-

-  Pebbles, on, 106.

-

-  Pendulum Experiments, 16-22.

-

-  Pendulum, the Earth weighed by, 200.

-

-  Pendulums, Influence of on each other, 200.

-

-  Perpetual Fire, 117.

-

-  Petrifaction of Human Bodies, 131.

-

-  Phenomena, Mutual Relations of, 4.

-

-  Philosophers’ False Estimates, 5.

-

-  Phosphorescence of Plants, 35.

-

-  Phosphorescence of the Sea, 35.

-

-  Photo-galvanic Engraving, 47.

-

-  Photograph and Stereoscope, 47.

-

-  Photographic effects of Lightning, 45.

-

-  Photographic Surveying, 46.

-

-  Photographs on the Retina, 236.

-

-  Photography, Best Sky for, 45.

-

-  Photography, Magic of, 44.

-

-  Pisa, Leaning Tower of, 15.

-

-  Planetary System, Origin of our, 86.

-

-  Planets, Diversities of, 79.

-

-  Planetoids, List of the, and their Discoverers, 239.

-

-  Plato’s Survey of the Sciences, 2.

-

-  Pleiades, the, 77.

-

-  Plurality of Worlds, 57.

-

-  Polar Ice, Immensity of, 181.

-

-  Polar Iceberg, 180.

-

-  Polarisation of Light, 33.

-

-  Pole, Open Sea at the, 181.

-

-  Pole-Star of 4000 years ago, 76.

-

-  Profitable Science, 139.

-

-  Pterodactyl, the, 130.

-

-  Pyramid, Duration of the, 14.

-

-

-  Quartz, Down of, 42.

-

-

-  Rain, All in the World, 155.

-

-  Rain, an Inch on the Atlantic, 156.

-

-  Rain-Drops, Size of, 154.

-

-  Rain, How the North Wind drives it away, 154.

-

-  Rain, Philosophy of, 153.

-

-  Rainless Districts, 155.

-

-  Rain-making Vapour, from South to North, 152.

-

-  Rainy Climate, Inordinate, 154.

-

-  Red Sea and Mediterranean Levels, 175.

-

-  Red Sea, Colour of, 176.

-

-  Repulsion of Bodies, 216.

-

-  Rhinoceros of Britain, 135.

-

-  River-water on the Ocean, 181.

-

-  Rose, no Fossil, 142.

-

-  Rosse, the Earl of, his “Telescope,” 96-99.

-

-  Rotation-Magnetism discovered, 199.

-

-  Rotation, the Axis of, 11.

-

-

-  St. Paul’s Cathedral, how protected from Lightning, 167.

-

-  Salt, All in the Sea, 179.

-

-  Salt Lake of Utah, 113.

-

-  Salt, Solvent Action of, 115.

-

-  Saltness of the Sea, How to tell, 179.

-

-  Sand in the Hour-glass, 20.

-

-  Sand of the Sea and Desert, 106.

-

-  Saturn’s Ring, Was it known to the Ancients?, 81.

-

-  Schwabe, on Sun-Spots, 68.

-

-  Science at Oxford and Cambridge, 1.

-

-  Science of the Ancient World, 1.

-

-  Science, Theoretical, Practical Results of, 4.

-

-  Sciences, Plato’s Survey of, 2.

-

-  Scientific Treatise, the Earliest English, 5.

-

-  Scoresby, Dr., on the Rosse Telescope, 99.

-

-  Scratches, Colours of, 36.

-

-  Sea, Bottles and Currents at, 172.

-

-  Sea, Bottom of, a burial-place, 177.

-

-  Sea, Circulation of the, 170.

-

-  Sea, Climates of the, 170.

-

-  Sea, Deep, Life of the, 174.

-

-  Sea, Greatest ascertained Depth of, 175.

-

-  Sea, Solitude at, 172.

-

-  Sea, Temperature of the, 170.

-

-  Sea, Why is it Salt?, 177.

-

-  Seas, Primeval, Depth of, 234.

-

-  Sea-breezes and Land-breezes illustrated, 150.

-

-  Sea-milk, What is it?, 176.

-

-  Sea-routes, How shortened, 184.

-

-  Sea-shells and Animalcules, Services of, 234.

-

-  Sea-shells, Why found at Great Heights, 106.

-

-  Sea-water, to imitate, 235.

-

-  Sea-water, Properties of, 179.

-

-  Serapis, Temple of, Successive Changes in, 111.

-

-  Sheep, Geology of the, 138.

-

-  Shells, Geometry of, 232.

-

-  Shells, Hydraulic Theory of, 233.

-

-  Siamese Twins, the, galvanised, 203.

-

-  Skin, Dark Colour of the, 63.

-

-  Smith, William, the Geologist, 126.

-

-  Snow, Absence of in Siberia, 159.

-

-  Snow, Impurity of, 158.

-

-  Snow Phenomenon, 158.

-

-  Snow, Warmth of, in Arctic Latitudes, 158.

-

-  Snow-capped Volcano, the, 119.

-

-  Snow-crystals observed by the Chinese, 159.

-

-  Soap-bubble, Science of the, 48.

-

-  Solar Heat, Extreme, 63.

-

-  Solar System, Velocity of, 59.

-

-  Sound, Figures produced by, 28.

-

-  Sound in rarefied Air, 27.

-

-  Sounding Sand, 27.

-

-  Space, Infinite, 86.

-

-  Speed, Varieties of, 17.

-

-  Spheres, Music of the, 55.

-

-  Spots on the Sun, 67.

-

-  Star, Fixed, the nearest, 78.

-

-  Stars’ Colour, Change in, 77.

-

-  Star’s Light sixteen times that of the Sun, 79.

-

-  Stars, Number of, 75.

-

-  Stars seen by Daylight, 102.

-

-  Stars that have disappeared, 76.

-

-  Stars, Why created, 75.

-

-  Stereoscope and Photograph, 47.

-

-  Stereoscope simplified, 47.

-

-  Storm, Impetus of, 164.

-

-  Storms, Revolving, 164.

-

-  Storms, to tell the Approach of, 163.

-

-  Storm-glass, How to make, 164.

-

-  Succession of life in Time, 128.

-

-  Sun, Actinic Power of, 62.

-

-  Sun and Fixed Stars’ Light compared, 64.

-

-  Sun and Terrestrial Magnetism, 64.

-

-  “Sun Darkened,” 64.

-

-  Sun, Great Size of, on Horizon, 61.

-

-  Sun, Heating Power of, 62.

-

-  Sun, Lost Heat of, 103.

-

-  Sun, Luminous Disc of, 60.

-

-  Sun, Nature of the, 59, 238.

-

-  Sun, Spots on, 67.

-

-  Sun, Translatory Motion of, 61.

-

-  Sun’s Distance by the Yard Measure, 66.

-

-  Sun’s Heat, Is it decreasing?, 65.

-

-  Sun’s Rays increasing the Strength of Magnets, 196.

-

-  Sun’s Light and Terrestrial Lights, 61.

-

-  Sun-dial, Universal, 65.

-

-

-  Telegraph, the Atlantic, 226.

-

-  Telegraph, the Electric, 220.

-

-  Telescope and Microscope, the, 38.

-

-  Telescope, Galileo’s, 93.

-

-  Telescope, Herschel’s, 95.

-

-  Telescope, Newton’s first Reflecting, 94.

-

-  Telescopes, Antiquity of, 94.

-

-  Telescopes, Gigantic, proposed, 99.

-

-  Telescopes, the Earl of Rosse’s, 96.

-

-  Temperature and Electricity, 208.

-

-  Terrestrial Magnetism, Origin of, 200.

-

-  Thames, the, and its Salt-water Bed, 182.

-

-  Threads, the two Electric, 215.

-

-  Thunderstorm seen from a Balloon, 169.

-

-  Tides, How produced by Sun and Moon, 66.

-

-  Time an Element of Force, 19.

-

-  Time, Minute Measurement of, 194.

-

-  Topaz, Transmutation of, 37.

-

-  Trilobite, the, 138.

-

-  Tuning-fork a Flute-player, 28.

-

-  Twilight, Beauty of, 148.

-

-

-  Universe, Vast Numbers in, 75.

-

-  Utah, Salt Lake of, 113.

-

-

-  Velocity of the Solar System, 59.

-

-  Vesta and Pallas, Speculations on, 82.

-

-  Vesuvius, Great Eruptions of, 119.

-

-  Vibration of Heated Metals, 188.

-

-  Visibility of Objects, 30.

-

-  Voice, Human, Audibility of, 27.

-

-  Volcanic Action and Geological Change, 118.

-

-  Volcanic Dust, Travels of, 119.

-

-  Volcanic Islands, Disappearance of, 117.

-

-  Voltaic Battery and the Gymnotus, 206.

-

-  Voltaic Currents in Mines, 206.

-

-  Voltaic Electricity discovered, 205.

-

-

-  Watches, Harrison’s Prize, 229.

-

-  Water decomposed by Electricity, 208.

-

-  Water, Running, Force of, 114.

-

-  Waters of the Globe gradually decreasing, 113.

-

-  Water-Purifiers, Natural, 234.

-

-  Waterspouts, How formed in the Java Sea, 160.

-

-  Waves, Cause of, 183.

-

-  Waves, Force of, 184.

-

-  Waves, Rate of Travelling, 183.

-

-  Wenham-Lake Ice, Purity of, 161.

-

-  West, Superior Salubrity of, 150.

-

-  “White Water,” and Luminous Animals at Sea, 173.

-

-  Winds, Transporting Power of, 163.

-

-  Wollaston’s Minute Battery, 204.

-

-  World, All the, in Motion, 11.

-

-  World, the, in a Nutshell, 13.

-

-  Worlds, More than One, 56.

-

-  Worlds to come, 58.

-

-

-LONDON: ROBSON, LEVEY, AND FRANKLYN, GREAT NEW STREET AND PETTER LANE,

-E.C.

-

-

-

-

-Transcriber’s Notes

-

-

-Punctuation, hyphenation, and spelling were made consistent when a

-predominant preference was found in this book; otherwise they were not

-changed.

-

-Simple typographical errors were corrected; occasional unbalanced

-quotation marks retained.

-

-Ambiguous hyphens at the ends of lines were retained.

-

-Some numbers in equations include a hyphen to separate the fractional

-and integer parts. These are not minus signs, which, like other

-arithmetic operators, are surrounded by spaces.

-

-The original book apparently used a smaller font for multiple reasons,

-but as those reasons were not always clear to the Transcriber, smaller

-text is indented by 2 spaces in the Plain Text version of this eBook,

-and is displayed smaller in other versions.

-

-Footnotes, originally at the bottoms of pages, have been collected and

-repositioned just before the Index.

-

-Page 59: “95 × 1·623 = 154·185” was misprinted as “95 + 1·623 =

-154·185” and has been corrected here.

-

-The Table of Contents does not list the “Phenomena of Heat” chapter,

-which begins on page 185; nor the Index, which begins on page 242.

-

-Page 95: “adjustible” was printed that way.

-

-Page 151: Missing closing quotation mark added after “rapidly evaporate

-in space.” It may belong elsewhere.

-

-Page 221: Missing closing quotation mark not added for phrase beginning

-“it is a fine invention”.

-

-

-

-

-

-

-

-End of the Project Gutenberg EBook of Curiosities of Science, Past and

-Present, by John Timbs

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+*** START OF THE PROJECT GUTENBERG EBOOK 48516 ***
+
+    NEW WORK ON PAINTING.
+
+    _Just ready, in small 8vo, with Frontispiece and Vignette_,
+
+    PAINTING
+    POPULARLY EXPLAINED;
+
+    WITH
+    The Practice of the Art,
+    AND
+    HISTORICAL NOTICES OF ITS PROGRESS.
+
+    BY
+    THOMAS J. GULLICK, PAINTER,
+    AND
+    JOHN TIMBS, F.S.A.
+
+
+The plan of this work is thus sketched in the _Introduction_:
+
+  “There have been in the history of Art, four grand styles of
+  imitating Nature--Tempera, Encaustic, Fresco, and Oil. These,
+  together with the minor modes of Painting, we propose arranging
+  in something like chronological sequence; but our design being
+  to offer an explanation of the Art derived from practical
+  acquaintance, rather than attempt to give its history, we shall
+  confine ourselves for the most part to so much only of the History
+  of Painting as is necessary to elucidate the origin of the
+  different practices which have obtained at different periods.”
+
+  By this means, the Authors hope to produce a work which may be
+  valuable to the Amateur, and interesting to the Connoisseur, the
+  Artist, and the General Reader.
+
+
+LONDON: KENT & CO. (LATE BOGUE), FLEET STREET.
+
+[Illustration: MOUTH OF THE GREAT ROSSE TELESCOPE, AT PARSONSTOWN.
+
+FROM A PHOTOGRAPH.]
+
+
+
+
+    Things not generally Known
+    Familiarly Explained.
+
+
+    CURIOSITIES OF SCIENCE,
+
+    Past and Present.
+
+    A BOOK FOR OLD AND YOUNG.
+
+
+    BY JOHN TIMBS, F.S.A.
+
+    AUTHOR OF THINGS NOT GENERALLY KNOWN; AND EDITOR OF THE
+    YEAR-BOOK OF FACTS.
+
+    [Illustration: Model of the Safety-Lamp, made by Sir Humphry
+       Davy’s own hands; in the possession of the Royal Society.]
+
+
+    LONDON:
+    KENT AND CO. (LATE BOGUE), FLEET STREET.
+    MDCCCLVIII.
+
+
+
+
+    _The Author reserves the right of authorising a Translation of
+    this Work._
+
+
+    LONDON:
+    PRINTED BY LEVEY, ROBSON, AND FRANKLYN,
+    Great New Street and Fetter Lane.
+
+
+
+
+GENTLE READER,
+
+The volume of “CURIOSITIES” which I here present to your notice is a
+portion of the result of a long course of reading, observation, and
+research, necessary for the compilation of thirty volumes of “Arcana
+of Science” and “Year-Book of Facts,” published from 1828 to 1858.
+Throughout this period--nearly half of the Psalmist’s “days of our
+years”--I have been blessed with health and strength to produce these
+volumes, year by year (with one exception), upon the appointed day; and
+this with unbroken attention to periodical duties, frequently rendered
+harassing or ungenial. Nevertheless, during these three decades I
+have found my account in the increasing approbation of the reading
+public, which has been so largely extended to the series of “THINGS
+NOT GENERALLY KNOWN,” of which the present volume of “CURIOSITIES OF
+SCIENCE” is an instalment. I need scarcely add, that in its progressive
+preparation I have endeavoured to compare, weigh, and consider,
+the contents, so as to combine the experience of the Past with the
+advantages of the Present.
+
+In these days of universal attainments, when Science becomes not
+merely a luxury to the rich, but bread to the poor, and when the
+very amusements as well as the conveniences of life have taken a
+scientific colour, it is reasonable to hope that the present volume
+may be acceptable to a large class of seekers after “things not
+generally known.” For this purpose, I have aimed at soundness as well
+as popularity; although, for myself, I can claim little beyond being
+one of those industrious “ants of science” who garner facts, and by
+selection and comparison adapt them for a wider circle of readers
+than they were originally expected to reach. In each case, as far as
+possible, these “CURIOSITIES” bear the mint-mark of authority; and in
+the living list are prominent the names of Humboldt and Herschel, Airy
+and Whewell, Faraday, Brewster, Owen, and Agassiz, Maury, Wheatstone,
+and Hunt, from whose writings and researches the following pages are
+frequently enriched.
+
+The sciences here illustrated are, in the main, Astronomy and
+Meteorology; Geology and Paleontology; Physical Geography; Sound,
+Light, and Heat; Magnetism and Electricity,--the latter with special
+attention to the great marvel of our times, the Electro-magnetic
+Telegraph. I hope, at no very distant period, to extend the
+“CURIOSITIES” to another volume, to include branches of Natural and
+Experimental Science which are not here presented.
+
+            I. T.
+    _November 1858._
+
+
+
+
+CONTENTS.
+
+
+                                          PAGE
+    INTRODUCTORY                          1-10
+
+    PHYSICAL PHENOMENA                   11-26
+
+    SOUND AND LIGHT                      27-53
+
+    ASTRONOMY                           54-103
+
+    GEOLOGY AND PALEONTOLOGY           104-145
+
+    METEOROLOGICAL PHENOMENA           146-169
+
+    PHYSICAL GEOGRAPHY OF THE SEA      170-192
+
+    MAGNETISM AND ELECTRICITY          193-219
+
+    THE ELECTRIC TELEGRAPH             220-228
+
+    MISCELLANEA                        229-241
+
+
+
+
+The Frontispiece.
+
+THE GREAT ROSSE TELESCOPE.
+
+
+The originator and architect of this magnificent instrument had long
+been distinguished in scientific research as Lord Oxmantown; and
+may be considered to have gracefully commemorated his succession to
+the Earldom of Rosse, and his Presidency of the Royal Society, by
+the completion of this marvellous work, with which his name will be
+hereafter indissolubly associated.
+
+The Great Reflecting Telescope at Birr Castle (of which the
+Frontispiece represents a portion[1]) will be found fully described at
+pp. 96-99 of the present volume of _Curiosities of Science_.
+
+This matchless instrument has already disclosed “forms of stellar
+arrangement indicating modes of dynamic action never before
+contemplated in celestial mechanics.” “In these departments of
+research,--the examination of the configurations of nebulæ, and the
+resolution of nebulæ into stars (says the Rev. Dr. Scoresby),--the
+six-feet speculum has had its grandest triumphs, and the noble
+artificer and observer the highest rewards of his talents and
+enterprise. Altogether, the quantity of work done during a period of
+about seven years--including a winter when a noble philanthropy for
+a starving population absorbed the keenest interests of science--has
+been decidedly great; and the new knowledge acquired concerning the
+handiwork of the great Creator amply satisfying of even sanguine
+expectation.”
+
+
+
+
+The Vignette.
+
+SIR HUMPHRY DAVY’S OWN MODEL OF HIS SAFETY-LAMP.
+
+
+Of the several contrivances which have been proposed for safely
+lighting coal-mines subject to the visitation of fire-damp, or
+carburetted hydrogen, the Safety-Lamp of Sir Humphry Davy is the only
+one which has ever been judged safe, and been extensively employed. The
+inventor first turned his attention to the subject in 1815, when Davy
+began a minute chemical examination of fire-damp, and found that it
+required an admixture of a large quantity of atmospheric air to render
+it explosive. He then ascertained that explosions of inflammable gases
+were incapable of being passed through long narrow metallic tubes, and
+that this principle of security was still obtained by diminishing their
+length and increasing their number. This fact led to trials upon sieves
+made of wire-gauze; when Davy found that if a piece of wire-gauze was
+held over the flame of a lamp, or of coal-gas, it prevented the flame
+from passing; and he ascertained that a flame confined in a cylinder of
+very fine wire-gauze did not explode even in a mixture of oxygen and
+hydrogen, but that the gases burnt in it with great vivacity.
+
+These experiments served as the basis of the Safety-Lamp. The apertures
+in the gauze, Davy tells us in his work on the subject, should not
+be more than 1/22d of an inch square. The lamp is screwed on to the
+bottom of the wire-gauze cylinder. When it is lighted, and gradually
+introduced into an atmosphere mixed with fire-damp, the size and length
+of the flame are first increased. When the inflammable gas forms as
+much as 1/12th of the volume of air, the cylinder becomes filled with a
+feeble blue flame, within which the flame of the wick burns brightly,
+and the light of the wick continues till the fire-damp increases to
+1/6th or 1/5th; it is then lost in the flame of the fire-damp, which
+now fills the cylinder with a pretty strong light; and when the foul
+air constitutes one-third of the atmosphere it is no longer fit for
+respiration,--and this ought to be a signal to the miner to leave that
+part of the workings.
+
+Sir Humphry Davy presented his first communication respecting his
+discovery of the Safety-Lamp to the Royal Society in 1815. This was
+followed by a series of papers remarkable for their simplicity and
+clearness, crowned by that read on the 11th of January 1816, when the
+principle of the Safety-Lamp was announced, and Sir Humphry presented
+to the Society a model made by his own hands, which is to this day
+preserved in the collection of the Royal Society at Burlington House.
+From this interesting memorial the Vignette has been sketched.
+
+There have been several modifications of the Safety-Lamp, and the merit
+of the discovery has been claimed by others, among whom was Mr. George
+Stephenson; but the question was set at rest forty-one years since by
+an examination,--attested by Sir Joseph Banks, P.R.S., Mr. Brande, Mr.
+Hatchett, and Dr. Wollaston,--and awarding the independent merit to
+Davy.
+
+A more substantial, though not a more honourable, testimony of approval
+was given by the coal-owners, who subscribed 2500_l._ to purchase a
+superb service of plate, which was suitably inscribed and presented to
+Davy.[2]
+
+Meanwhile the Report by the Parliamentary Committee “cannot admit that
+the experiments (made with the Lamp) have any tendency to detract from
+the character of Sir Humphry Davy, or to disparage the fair value
+placed by himself upon his invention. The improvements are probably
+those which longer life and additional facts would have induced him to
+contemplate as desirable, and of which, had he not been the inventor,
+he might have become the patron.”
+
+The principle of the invention may be thus summed up. In the
+Safety-Lamp, the mixture of the fire-damp and atmospheric air within
+the cage of wire-gauze explodes upon coming in contact with the flame;
+but the combustion cannot pass through the wire-gauze, and being there
+imprisoned, cannot impart to the explosive atmosphere of the mine any
+of its force. This effect has been erroneously attributed to a cooling
+influence of the metal.
+
+Professor Playfair has eloquently described the Safety-Lamp of Davy as
+a present from philosophy to the arts; a discovery in no degree the
+effect of accident or chance, but the result of patient and enlightened
+research, and strongly exemplifying the great use of an immediate and
+constant appeal to experiment. After characterising the invention as
+the _shutting-up in a net of the most slender texture_ a most violent
+and irresistible force, and a power that in its tremendous effects
+seems to emulate the lightning and the earthquake, Professor Playfair
+thus concludes: “When to this we add the beneficial consequences, and
+the saving of the lives of men, and consider that the effects are to
+remain as long as coal continues to be dug from the bowels of the
+earth, it may be fairly said that there is hardly in the whole compass
+of art or science a single invention of which one would rather wish
+to be the author.... This,” says Professor Playfair, “is exactly such
+a case as we should choose to place before Bacon, were he to revisit
+the earth; in order to give him, in a small compass, an idea of the
+advancement which philosophy has made since the time when he had
+pointed out to her the route which she ought to pursue.”
+
+
+
+
+CURIOSITIES OF SCIENCE.
+
+
+
+
+Introductory.
+
+
+SCIENCE OF THE ANCIENT WORLD.
+
+In every province of human knowledge where we now possess a careful
+and coherent interpretation of nature, men began by attempting in
+bold flights to leap from obvious facts to the highest point of
+generality--to some wide and simple principle which after-ages had to
+reject. Thus, from the facts that all bodies are hot or cold, moist or
+dry, they leapt at once to the doctrine that the world is constituted
+of four elements--earth, air, fire, water; from the fact that the
+heavenly bodies circle the sky in courses which occur again and again,
+they at once asserted that they move in exact circles, with an exactly
+uniform motion; from the fact that heavy bodies fall through the air
+somewhat faster than light ones, it was assumed that all bodies fall
+quickly or slowly exactly in proportion to their weight; from the fact
+that the magnet attracts iron, and that this force of attraction is
+capable of increase, it was inferred that a perfect magnet would have
+an irresistible force of attraction, and that the magnetic pole of
+the earth would draw the nails out of a ship’s bottom which came near
+it; from the fact that some of the finest quartz crystals are found
+among the snows of the Alps, it was inferred that the crystallisation
+of gems is the result of intense and long-continued cold: and so on
+in innumerable instances. Such anticipations as these constituted
+the basis of almost all the science of the ancient world; for such
+principles being so assumed, consequences were drawn from them with
+great ingenuity, and systems of such deductions stood in the place of
+science.--_Edinburgh Review_, No. 216.
+
+
+SCIENCE AT OXFORD AND CAMBRIDGE.
+
+The earliest science of a decidedly English school is due, for the most
+part, to the University of Oxford, and specially to Merton College,--a
+foundation of which Wood remarks, that there was no other for two
+centuries, either in Oxford or Paris, which could at all come near it
+in the cultivation of the sciences. But he goes on to say that large
+chests full of the writers of this college were allowed to remain
+untouched by their successors for fear of the magic which was supposed
+to be contained in them. Nevertheless, it is not difficult to trace
+the liberalising effect of scientific study upon the University in
+general, and Merton College in particular; and it must be remembered
+that to the cultivation of the mind at Oxford we owe almost all the
+literary celebrity of the middle ages. In this period the University of
+Cambridge appears to have acquired no scientific distinction. Taking
+as a test the acquisition of celebrity on the continent, we find that
+Bacon, Sacrobosco, Greathead, Estwood, &c. were all of Oxford. The
+latter University had its morning of splendour while Cambridge was
+comparatively unknown; it had also its noonday, illustrated by such men
+as Briggs, Wren, Wallis, Halley, and Bradley.
+
+The age of science at Cambridge may be said to have begun with Francis
+Bacon; and but that we think much of the difference between him and
+his celebrated namesake lies more in time and circumstances than in
+talents or feelings, we would rather date from 1600 with the former
+than from 1250 with the latter. Praise or blame on either side is out
+of the question, seeing that the earlier foundation of Oxford, and its
+superiority in pecuniary means, rendered all that took place highly
+probable; and we are in a great measure indebted for the liberty of
+writing our thoughts, to the cultivation of the liberalising sciences
+at Oxford in the dark ages.
+
+With regard to the University of Cambridge, for a long time there
+hardly existed the materials of any proper instruction, even to the
+extent of pointing out what books should be read by a student desirous
+of cultivating astronomy.
+
+
+PLATO’S SURVEY OF THE SCIENCES.
+
+  Plato, like Francis Bacon, took a review of the sciences of his
+  time: he enumerates arithmetic and plane geometry, treated as
+  collections of abstract and permanent truths; solid geometry, which
+  he “notes as deficient” in his time, although in fact he and his
+  school were in possession of the doctrine of the “five regular
+  solids;” astronomy, in which he demands a science which should
+  be elevated above the mere knowledge of phenomena. The visible
+  appearances of the heavens only suggest the problems with which
+  true astronomy deals; as beautiful geometrical diagrams do not
+  prove, but only suggest geometrical propositions. Finally, Plato
+  notices the subject of harmonics, in which he requires a science
+  which shall deal with truths more exact than the ear can establish,
+  as in astronomy he requires truths more exact than the eye can
+  assure us of.
+
+  In a subsequent paper Plato speaks of _Dialectic_ as a still
+  higher element of a philosophical education, fitted to lead men
+  to the knowledge of real existences and of the supreme good. Here
+  he describes dialectic by its objects and purpose. In other places
+  dialectic is spoken of as a method or process of analysis; as in
+  the _Phædrus_, where Socrates describes a good dialectician as one
+  who can divide a subject according to its natural members, and not
+  miss the joint, like a bad carver. Xenophon says that Socrates
+  derived _dialectic_ from a term implying to _divide a subject into
+  parts_, which Mr. Grote thinks unsatisfactory as an etymology, but
+  which has indicated a practical connection in the Socratic school.
+  The result seems to be that Plato did not establish any method of
+  analysis of a subject as his dialectic; but he conceived that the
+  analytical habits formed by the comprehensive study of the exact
+  sciences, and sharpened by the practice of dialogue, would lead his
+  students to the knowledge of first principles.--_Dr. Whewell._
+
+
+FOLLY OF ATHEISM.
+
+Morphology, in natural science, teaches us that the whole animal
+and vegetable creation is formed upon certain fundamental types
+and patterns, which can be traced under various modifications and
+transformations through all the rich variety of things apparently of
+most dissimilar build. But here and there a scientific person takes
+it into his foolish head that there may be a set of moulds without
+a moulder, a calculated gradation of forms without a calculator, an
+ordered world without an ordering God. Now, this atheistical science
+conveys about as much meaning as suicidal life: for science is possible
+only where there are ideas, and ideas are only possible where there is
+mind, and minds are the offspring of God; and atheism itself is not
+merely ignorance and stupidity,--it is the purely nonsensical and the
+unintelligible.--_Professor Blackie_; _Edinburgh Essays_, 1856.
+
+
+THE ART OF OBSERVATION.
+
+To observe properly in the very simplest of the physical sciences
+requires a long and severe training. No one knows this so feelingly
+as the great discoverer. Faraday once said, that he always doubts his
+own observations. Mitscherlich on one occasion remarked to a man of
+science that it takes fourteen years to discover and establish a single
+new fact in chemistry. An enthusiastic student one day betook himself
+to Baron Cuvier with the exhibition of a new organ--a muscle which he
+supposed himself to have discovered in the body of some living creature
+or other; but the experienced and sagacious naturalist kindly bade the
+young man return to him with the same discovery in six months. The
+Baron would not even listen to the student’s demonstration, nor examine
+his dissection, till the eager and youthful discoverer had hung over
+the object of inquiry for half a year; and yet that object was a mere
+thing of the senses.--_North-British Review_, No. 18.
+
+
+MUTUAL RELATIONS OF PHENOMENA.
+
+In the observation of a phenomenon which at first sight appears to
+be wholly isolated, how often may be concealed the germ of a great
+discovery! Thus, when Galvani first stimulated the nervous fibre of
+the frog by the accidental contact of two heterogeneous metals, his
+contemporaries could never have anticipated that the action of the
+voltaic pile would discover to us in the alkalies metals of a silver
+lustre, so light as to swim on water, and eminently inflammable; or
+that it would become a powerful instrument of chemical analysis, and at
+the same time a thermoscope and a magnet. When Huyghens first observed,
+in 1678, the phenomenon of the polarisation of light, exhibited in the
+difference between two rays into which a pencil of light divides itself
+in passing through a doubly refracting crystal, it could not have been
+foreseen that a century and a half later the great philosopher Arago
+would, by his discovery of _chromatic polarisation_, be led to discern,
+by means of a small fragment of Iceland spar, whether solar light
+emanates from a solid body or a gaseous covering; or whether comets
+transmit light directly, or merely by reflection.--_Humboldt’s Cosmos_,
+vol. i.
+
+
+PRACTICAL RESULTS OF THEORETICAL SCIENCE.
+
+What are the great wonders, the great sources of man’s material
+strength, wealth, and comfort in modern times? The Railway, with its
+mile-long trains of men and merchandise, moving with the velocity of
+the wind, and darting over chasms a thousand feet wide; the Electric
+Telegraph, along which man’s thoughts travel with the velocity of
+light, and girdle the earth more quickly than Puck’s promise to his
+master; the contrivance by which the Magnet, in the very middle of
+a strip of iron, is still true to the distant pole, and remains a
+faithful guide to the mariner; the Electrotype process, by which a
+metallic model of any given object, unerringly exact, grows into
+being like a flower. Now, all these wonders are the result of recent
+and profound discoveries in theoretical science. The Locomotive
+Steam-engine, and the Steam-engine in all its other wonderful and
+invaluable applications, derives its efficacy from the discoveries, by
+Watt and others, of the laws of steam. The Railway Bridge is not made
+strong by mere accumulation of materials, but by the most exact and
+careful scientific examination of the means of giving the requisite
+strength to every part, as in the great example of Mr. Stephenson’s
+Britannia Bridge over the Menai Strait. The Correction of the Magnetic
+Needle in iron ships it would have been impossible for Mr. Airy to
+secure without a complete theoretical knowledge of the laws of
+Magnetism. The Electric Telegraph and the Electrotype process include
+in their principles and mechanism the most complete and subtle results
+of electrical and magnetical theory.--_Edinburgh Review_, No. 216.
+
+
+PERPETUITY OF IMPROVEMENT.
+
+In the progress of society all great and real improvements are
+perpetuated: the same corn which, four thousand years ago, was raised
+from an improved grass by an inventor worshiped for two thousand years
+in the ancient world under the name of Ceres, still forms the principal
+food of mankind; and the potato, perhaps the greatest benefit that the
+old has derived from the new world, is spreading over Europe, and will
+continue to nourish an extensive population when the name of the race
+by whom it was first cultivated in South America is forgotten.--_Sir H.
+Davy._
+
+
+THE EARLIEST ENGLISH SCIENTIFIC TREATISE.
+
+Geoffrey Chaucer, the poet, wrote a treatise on the Astrolabe for his
+son, which is the earliest English treatise we have met with on any
+scientific subject. It was not completed; and the apologies which
+Chaucer makes to his own child for writing in English are curious;
+while his inference that his son should therefore “pray God save the
+king that is lord of this language,” is at least as loyal as logical.
+
+
+PHILOSOPHERS’ FALSE ESTIMATES OF THEIR OWN LABOURS.
+
+Galileo was confident that the most important part of his contributions
+to the knowledge of the solar system was his Theory of the Tides--a
+theory which all succeeding astronomers have rejected as utterly
+baseless and untenable. Descartes probably placed far above his
+beautiful explanation of the rainbow, his _à priori_ theory of the
+existence of the vortices which caused the motion of the planets and
+satellites. Newton perhaps considered as one of the best parts of his
+optical researches his explanation of the natural colour of bodies,
+which succeeding optical philosophers have had to reject; and he
+certainly held very strongly the necessity of a material cause for
+gravity, which his disciples have disregarded. Davy looked for his
+greatest triumph in the application of his discoveries to prevent
+the copper bottoms of ships from being corroded. And so in other
+matters.--_Edinburgh Review_, No. 216.
+
+
+RELICS OF GENIUS.
+
+Professor George Wilson, in a lecture to the Scottish Society of
+Arts, says: “The spectacle of these things ministers only to the
+good impulses of humanity. Isaac Newton’s telescope at the Royal
+Society of London; Otto Guericke’s air-pump in the Library at Berlin;
+James Watt’s repaired Newcomen steam-engine in the Natural-Philosophy
+class-room of the College at Glasgow; Fahrenheit’s thermometer in
+the corresponding class-room of the University of Edinburgh; Sir H.
+Davy’s great voltaic battery at the Royal Institution, London, and
+his safety-lamp at the Royal Society; Joseph Black’s pneumatic trough
+in Dr. Gregory’s possession; the first wire which Faraday made rotate
+electro-magnetically, at St. Bartholomew’s Hospital; Dalton’s atomic
+models at Manchester; and Kemp’s liquefied gases in the Industrial
+Museum of Scotland,--are alike personal relics, historical monuments,
+and objects of instruction, which grow more and more precious every
+year, and of which we never can have too many.”
+
+
+THE ROYAL SOCIETY: THE NATURAL AND SUPERNATURAL.
+
+The Royal Society was formed with the avowed object of increasing
+knowledge by direct experiment; and it is worthy of remark, that the
+charter granted by Charles II. to this celebrated institution declares
+that its object is the extension of natural knowledge, as opposed to
+that which is supernatural.
+
+Dr. Paris (_Life of Sir H. Davy_, vol. ii. p. 178) says: “The charter
+of the Royal Society states that it was established for the improvement
+of _natural_ science. This epithet _natural_ was originally intended to
+imply a meaning, of which very few persons, I believe, are aware. At
+the period of the establishment of the society, the arts of witchcraft
+and divination were very extensively encouraged; and the word _natural_
+was therefore introduced in contradistinction to _supernatural_.”
+
+
+THE PHILOSOPHER BOYLE.
+
+After the death of Bacon, one of the most distinguished Englishmen
+was certainly Robert Boyle, who, if compared with his contemporaries,
+may be said to rank immediately below Newton, though of course very
+inferior to him as an original thinker. Boyle was the first who
+instituted exact experiments into the relation between colour and heat;
+and by this means not only ascertained some very important facts, but
+laid a foundation for that union between optics and thermotics, which,
+though not yet completed, now merely waits for some great philosopher
+to strike out a generalisation large enough to cover both, and thus
+fuse the two sciences into a single study. It is also to Boyle, more
+than to any other Englishman, that we owe the science of hydrostatics
+in the state in which we now possess it.[3] He is also the original
+discoverer of that beautiful law, so fertile in valuable results,
+according to which the elasticity of air varies as its density. And,
+in the opinion of one of the most eminent modern naturalists, it was
+Boyle who opened up those chemical inquiries which went on accumulating
+until, a century later, they supplied the means by which Lavoisier and
+his contemporaries fixed the real basis of chemistry, and enabled it
+for the first time to take its proper stand among those sciences that
+deal with the external world.--_Buckle’s History of Civilization_, vol.
+i.
+
+
+SIR ISAAC NEWTON’S ROOMS AND LABORATORY IN TRINITY COLLEGE, CAMBRIDGE.
+
+Of the rooms occupied by Newton during his early residence at
+Cambridge, it is now difficult to settle the locality. The chamber
+allotted to him as Fellow, in 1667, was “the Spiritual Chamber,”
+conjectured to have been the ground-room, next the chapel, but it is
+not certain that he resided there. The rooms in which he lived from
+1682 till he left Cambridge, are in the north-east corner of the great
+court, on the first floor, on the right or north of the gateway or
+principal entrance to the college. His laboratory, as Dr. Humphrey
+Newton tell us, was “on the left end of the garden, near the east end
+of the chapel; and his telescope (refracting) was five feet long, and
+placed at the head of the stairs, going down into the garden.”[4] The
+east side of Newton’s rooms has been altered within the last fifty
+years: Professor Sedgwick, who came up to college in 1804, recollects a
+wooden room, supported on an arcade, shown in Loggan’s view, in place
+of which arcade is now a wooden wall and brick chimney.
+
+  Dr. Humphrey Newton relates that in college Sir Isaac very rarely
+  went to bed till two or three o’clock in the morning, sometimes
+  not till five or six, especially at spring and fall of the leaf,
+  when he used to employ about six weeks in his laboratory, the
+  fire scarcely going out either night or day; he sitting up one
+  night, and Humphrey another, till he had finished his chemical
+  experiments. Dr. Newton describes the laboratory as “well furnished
+  with chymical materials, as bodyes, receivers, heads, crucibles,
+  &c., which was made very little use of, ye crucibles excepted,
+  in which he fused his metals: he would sometimes, though very
+  seldom, look into an old mouldy book, which lay in his laboratory;
+  I think it was titled _Agricola de Metallis_, the transmuting of
+  metals being his chief design, for which purpose antimony was a
+  great ingredient.” “His brick furnaces, _pro re nata_, he made and
+  altered himself without troubling a bricklayer.” “What observations
+  he might make with his telescope, I know not, but several of his
+  observations about comets and the planets may be found scattered
+  here and there in a book intitled _The Elements of Astronomy_, by
+  Dr. David Gregory.”[5]
+
+
+NEWTON’S “APPLE-TREE.”
+
+Curious and manifold as are the trees associated with the great names
+of their planters, or those who have sojourned in their shade, the
+Tree which, by the falling of its fruit, suggested to Newton the idea
+of Gravity, is of paramount interest. It appears that, in the autumn
+of 1665, Newton left his college at Cambridge for his paternal home
+at Woolsthorpe. “When sitting alone in the garden,” says Sir David
+Brewster, “and speculating on the power of gravity, it occurred to him,
+that as the same power by which the apple fell to the ground was not
+sensibly diminished at the greatest distance from the centre of the
+earth to which we can reach, neither at the summits of the loftiest
+spires, nor on the tops of the highest mountains, it might extend to
+the moon and retain her in her orbit, in the same manner as it bends
+into a curve a stone or a cannon-ball when projected in a straight line
+from the surface of the earth.”--_Life of Newton_, vol. i. p. 26. Sir
+David Brewster notes, that neither Pemberton nor Whiston, who received
+from Newton himself his first ideas of gravity, records this story of
+the falling apple. It was mentioned, however, to Voltaire by Catherine
+Barton, Newton’s niece; and to Mr. Green by Martin Folkes, President
+of the Royal Society. Sir David Brewster saw the reputed apple-tree in
+1814, and brought away a portion of one of its roots. The tree was so
+much decayed that it was cut down in 1820, and the wood of it carefully
+preserved by Mr. Turnor, of Stoke Rocheford.
+
+  De Morgan (in _Notes and Queries_, 2d series, No. 139, p. 169)
+  questions whether the fruit was an apple, and maintains that the
+  anecdote rests upon very slight authority; more especially as
+  the idea had for many years been floating before the minds of
+  physical inquirers; although Newton cleared away the confusions and
+  difficulties which prevented very able men from proceeding beyond
+  conjecture, and by this means established _universal_ gravitation.
+
+
+NEWTON’S “PRINCIPIA.”
+
+“It may be justly said,” observes Halley, “that so many and so valuable
+philosophical truths as are herein discovered and put past dispute
+were never yet owing to the capacity and industry of any one man.”
+“The importance and generality of the discoveries,” says Laplace, “and
+the immense number of original and profound views, which have been the
+germ of the most brilliant theories of the philosophers of this (18th)
+century, and all presented with much elegance, will ensure to the work
+on the _Mathematical Principles of Natural Philosophy_ a preëminence
+above all the other productions of human genius.”
+
+
+DESCARTES’ LABOURS IN PHYSICS.
+
+The most profound among the many eminent thinkers France has produced,
+is Réné Descartes, of whom the least that can be said is, that he
+effected a revolution more decisive than has ever been brought about
+by any other single mind; that he was the first who successfully
+applied algebra to geometry; that he pointed out the important law of
+the sines; that in an age in which optical instruments were extremely
+imperfect, he discovered the changes to which light is subjected in
+the eye by the crystalline lens; that he directed attention to the
+consequences resulting from the weight of the atmosphere; and that he
+moreover detected the causes of the rainbow. At the same time, and
+as if to combine the most varied forms of excellence, he is not only
+allowed to be the first geometrician of the age, but by the clearness
+and admirable precision of his style, he became one of the founders
+of French prose. And, although he was constantly engaged in those
+lofty inquiries into the nature of the human mind, which can never
+be studied without wonder, he combined with them a long course of
+laborious experiment upon the animal frame, which raised him to the
+highest rank among the anatomists of his time. The great discovery
+made by Harvey of the Circulation of the Blood was neglected by most
+of his contemporaries; but it was at once recognised by Descartes, who
+made it the basis of the physiological part of his work on man. He was
+likewise the discoverer of the lacteals by Aselli, which, like every
+great truth yet laid before the world, was at its first appearance,
+not only disbelieved, but covered with ridicule.--_Buckle’s History of
+Civilization_, vol. i.
+
+
+CONIC SECTIONS.
+
+If a cone or sugar-loaf be cut through in certain directions, we shall
+obtain figures which are termed conic sections: thus, if we cut through
+a sugar-loaf parallel to its base or bottom, the outline or edge of the
+loaf where it is cut will be _a circle_. If the cut is made so as to
+slant, and not be parallel to the base of the loaf, the outline is an
+_ellipse_, provided the cut goes quite through the sides of the loaf
+all round; but if it goes slanting, and parallel to the line of the
+loaf’s side, the outline is a _parabola_, a conic section or curve,
+which is distinguished by characteristic properties, every point of it
+bearing a certain fixed relation to a certain point within it, as the
+circle does to its centre.--_Dr. Paris’s Notes to Philosophy in Sport,
+&c._
+
+
+POWER OF COMPUTATION.
+
+The higher class of mathematicians, at the end of the seventeenth
+century, had become excellent computers, particularly in England,
+of which Wallis, Newton, Halley, the Gregorys, and De Moivre, are
+splendid examples. Before results of extreme exactness had become
+quite familiar, there was a gratifying sense of power in bringing out
+the new methods. Newton, in one of his letters to Oldenburg, says
+that he was at one time too much attached to such things, and that
+he should be ashamed to say to what number of figures he was in the
+habit of carrying his results. The growth of power of computation on
+the Continent did not, however, keep pace with that of the same in
+England. In 1696, De Laguy, a well-known writer on algebra, and a
+member of the Academy of Sciences, said that the most skilful computer
+could not, in less than a month, find within a unit the cube root of
+696536483318640035073641037.--_De Morgan._
+
+
+“THE SCIENCE OF THE COSMOS.”
+
+Humboldt, characterises this “uncommon but definite expression” as the
+treating of “the assemblage of all things with which space is filled,
+from the remotest nebulæ to the climatic distribution of those delicate
+tissues of vegetable matter which spread a variegated covering over the
+surface of our rocks.” The word _cosmos_, which primitively, in the
+Homeric ages, indicated an idea of order and harmony, was subsequently
+adopted in scientific language, where it was gradually applied to the
+order observed in the movements of the heavenly bodies; to the whole
+universe; and then finally to the world in which this harmony was
+reflected to us.
+
+
+
+
+Physical Phenomena.
+
+
+ALL THE WORLD IN MOTION.
+
+Humboldt, in his _Cosmos_,[6] gives the following beautiful
+illustrative proofs of this phenomenon:
+
+  If, for a moment, we imagine the acuteness of our senses
+  preternaturally heightened to the extreme limits of telescopic
+  vision, and bring together events separated by wide intervals of
+  time, the apparent repose which reigns in space will suddenly
+  vanish; countless stars will be seen moving in groups in various
+  directions; nebulæ wandering, condensing, and dissolving like
+  cosmical clouds; the milky way breaking up in parts, and its
+  veil rent asunder. In every point of the celestial vault we
+  shall recognise the dominion of progressive movement, as on the
+  surface of the earth where vegetation is constantly putting forth
+  its leaves and buds, and unfolding its blossoms. The celebrated
+  Spanish botanist, Cavanilles, first conceived the possibility of
+  “seeing grass grow,” by placing the horizontal micrometer wire
+  of a telescope, with a high magnifying power, at one time on the
+  point of a bamboo shoot, and at another on the rapidly unfolding
+  flowering stem of an American aloe; precisely as the astronomer
+  places the cross of wires on a culminating star. Throughout the
+  whole life of physical nature--in the organic as in the sidereal
+  world--existence, preservation, production, and development, are
+  alike associated with motion as their essential condition.
+
+
+THE AXIS OF ROTATION.
+
+It is remarkable as a mechanical fact, that nothing is so permanent in
+nature as the Axis of Rotation of any thing which is rapidly whirled.
+We have examples of this in every-day practice. The first is the
+motion of _a boy’s hoop_. What keeps the hoop from falling?--It is its
+rotation, which is one of the most complicated subjects in mechanics.
+
+Another thing pertinent to this question is, _the motion of a quoit_.
+Every body who ever threw a quoit knows that to make it preserve its
+position as it goes through the air, it is necessary to give it a
+whirling motion. It will be seen that while whirling, it preserves its
+plane, whatever the position of the plane may be, and however it may
+be inclined to the direction in which the quoit travels. Now, this has
+greater analogy with the motion of the earth than any thing else.
+
+Another illustration is _the motion of a spinning top_. The greatest
+mathematician of the last century, the celebrated Euler, has written
+a whole book on the motion of a top, and his Latin treatise _De motu
+Turbinis_ is one of the most remarkable books on mechanics. The motion
+of a top is a matter of the greatest importance; it is applicable
+to the elucidation of some of the greatest phenomena of nature. In
+all these instances there is this wonderful tendency in rotation to
+preserve the axis of rotation unaltered.--_Prof. Airy’s Lect. on
+Astronomy._
+
+
+THE EARTH’S ANNUAL MOTION.
+
+In conformity with the Copernican view of our system, we must learn to
+look upon the sun as the comparatively motionless centre about which
+the earth performs an annual elliptic orbit of the dimensions and
+excentricity, and with a velocity, regulated according to a certain
+assigned law; the sun occupying one of the foci of the ellipse, and
+from that station quietly disseminating on all sides its light and
+heat; while the earth travelling round it, and presenting itself
+differently to it at different times of the year and day, passes
+through the varieties of day and night, summer and winter, which we
+enjoy.--_Sir John Herschel’s Outlines of Astronomy._
+
+Laplace has shown that the length of the day has not varied the
+hundredth part of a second since the observations of Hipparchus, 2000
+years ago.
+
+
+STABILITY OF THE OCEAN.
+
+In submitting this question to analysis, Laplace found that the
+_equilibrium of the ocean is stable if its density is less than
+the mean density of the earth_, and that its equilibrium cannot be
+subverted unless these two densities are equal, or that of the earth
+less than that of its waters. The experiments on the attraction of
+Schehallien and Mont Cenis, and those made by Cavendish, Reich, and
+Baily, with balls of lead, demonstrate that the mean density of the
+earth is at least _five_ times that of water, and hence the stability
+of the ocean is placed beyond a doubt. As the seas, therefore, have at
+one time covered continents which are now raised above their level,
+we must seek for some other cause of it than any want of stability in
+the equilibrium of the ocean. How beautifully does this conclusion
+illustrate the language of Scripture, “Hitherto shalt thou come, but no
+further”! (_Job_ xxxviii. 11.)
+
+
+COMPRESSION OF BODIES.
+
+Sir John Leslie observes, that _air compressed_ into the fiftieth
+part of its volume has its elasticity fifty times augmented: if it
+continued to contract at that rate, it would, from its own incumbent
+weight, acquire the density of water at the depth of thirty-four
+miles. But water itself would have its density doubled at the depth
+of ninety-three miles, and would attain the density of quicksilver at
+the depth of 362 miles. In descending, therefore, towards the centre,
+through nearly 4000 miles, the condensation of ordinary substances
+would surpass the utmost powers of conception. Dr. Young says, that
+steel would be compressed into one-fourth, and stone into one-eighth,
+of its bulk at the earth’s centre.--_Mrs. Somerville._
+
+
+THE WORLD IN A NUTSHELL.
+
+From the many proofs of the non-contact of the atoms, even in the
+most solid parts of bodies; from the very great space obviously
+occupied by pores--the mass having often no more solidity than a heap
+of empty boxes, of which the apparently solid parts may still be as
+porous in a second degree and so on; and from the great readiness
+with which light passes in all directions through dense bodies, like
+glass, rock-crystal, diamond, &c., it has been argued that there is so
+exceedingly little of really solid matter even in the densest mass,
+that _the whole world_, if the atoms could be brought into absolute
+contact, _might be compressed into a nutshell_. We have as yet no means
+of determining exactly what relation this idea has to truth.--_Arnott._
+
+
+THE WORLD OF ATOMS.
+
+The infinite groups of atoms flying through all time and space, in
+different directions and under different laws, have interchangeably
+tried and exhibited every possible mode of rencounter: sometimes
+repelled from each other by concussion; and sometimes adhering to each
+other from their own jagged or pointed construction, or from the casual
+interstices which two or more connected atoms must produce, and which
+may be just adapted to those of other figures,--as globular, oval, or
+square. Hence the origin of compound and visible bodies; hence the
+origin of large masses of matter; hence, eventually, the origin of the
+world.--_Dr. Good’s Book of Nature._
+
+The great Epicurus speculated on “the plastic nature” of atoms, and
+attributed to this _nature_ the power they possess of arranging
+themselves into symmetric forms. Modern philosophers satisfy themselves
+with attraction; and reasoning from analogy, imagine that each atom has
+a polar system.--_Hunt’s Poetry of Science._
+
+
+MINUTE ATOMS OF THE ELEMENTS: DIVISIBILITY OF MATTER.
+
+So minute are the parts of the elementary bodies in their ultimate
+state of division, in which condition they are usually termed _atoms_,
+as to elude all our powers of inspection, even when aided by the most
+powerful microscopes. Who can see the particles of gold in a solution
+of that metal in _aqua regia_, or those of common salt when dissolved
+in water? Dr. Thomas Thomson has estimated the bulk of an ultimate
+particle or atom of lead as less than 1/888492000000000th of a cubic
+inch, and concludes that its weight cannot exceed the 1/310000000000th
+of a grain.
+
+This curious calculation was made by Dr. Thomson, in order to show to
+what degree Matter could be divided, and still be sensible to the eye.
+He dissolved a grain of nitrate of lead in 500,000 grains of water,
+and passed through the solution a current of sulphuretted hydrogen;
+when the whole liquid became sensibly discoloured. Now, a grain of
+water may be regarded as being almost equal to a drop of that liquid,
+and a drop may be easily spread out so as to cover a square inch of
+surface. But under an ordinary microscope the millionth of a square
+inch may be distinguished by the eye. The water, therefore, could be
+divided into 500,000,000,000 parts. But the lead in a grain of nitrate
+of lead weighs 0·62 of a grain; an atom of lead, accordingly, cannot
+weigh more than 1/810000000000th of a grain; while the atom of sulphur,
+which in combination with the lead rendered it visible, could not
+weigh more than 1/2015000000000, that is, the two-billionth part of a
+grain.--_Professor Low_; _Jameson’s Journal_, No. 106.
+
+
+WEIGHT OF AIR.
+
+Air can be so rarefied that the contents of a cubic foot shall not
+weigh the tenth part of a grain: if a quantity that would fill a space
+the hundredth part of an inch in diameter be separated from the rest,
+the air will still be found there, and we may reasonably conceive that
+there may be several particles present, though the weight is less than
+the seventeen-hundred-millionth of a grain.
+
+
+DURATION OF THE PYRAMID.
+
+The great reason of the duration of the pyramid above all other forms
+is, that it is most fitted to resist the force of gravitation. Thus the
+Pyramids of Egypt are the oldest monuments in the world.
+
+
+INERTIA ILLUSTRATED.
+
+Many things of common occurrence (says Professor Tyndall) are to be
+explained by reference to the quality of inactivity. We will here state
+a few of them.
+
+When a railway train is moving, if it strike against any obstacle which
+arrests its motion, the passengers are thrown forward in the direction
+in which the train was proceeding. Such accidents often occur on a
+small scale, in attaching carriages at railway stations. The reason is,
+that the passengers share the motion of the train, and, as matter, they
+tend to persist in motion. When the train is suddenly checked, this
+tendency exhibits itself by the falling forward referred to. In like
+manner, when a train previously at rest is suddenly set in motion, the
+tendency of the passengers to remain at rest evinces itself by their
+falling in a direction opposed to that in which the train moves.
+
+
+THE LEANING TOWER OF PISA.[7]
+
+Sir John Leslie used to attribute the stability of this tower to
+the cohesion of the mortar it is built with being sufficient to
+maintain it erect, in spite of its being out of the condition required
+by physics--to wit, that “in order that a column shall stand, a
+perpendicular let fall from the centre of gravity must fall within the
+base.” Sir John describes the Tower of Pisa to be in violation of this
+principle; but, according to later authorities, the perpendicular falls
+within the base.
+
+
+EARLY PRESENTIMENTS OF CENTRIFUGAL FORCES.
+
+Jacobi, in his researches on the mathematical knowledge of the
+Greeks, comments on “the profound consideration of nature evinced by
+Anaxagoras, in whom we read with astonishment a passage asserting that
+the moon, if the centrifugal force were intermitted, would fall to the
+earth like a stone from a sling.” Anaxagoras likewise applied the same
+theory of “falling where the force of rotation had been intermitted”
+to all the material celestial bodies. In Aristotle and Simplicius may
+also be traced the idea of “the non-falling of heavenly bodies when the
+rotatory force predominates over the actual falling force, or downward
+attraction;” and Simplicius mentions that “water in a phial is not
+spilt when the movement of rotation is more rapid than the downward
+movement of the water.” This is illustrated at the present day by
+rapidly whirling a pail half-filled with water without spilling a drop.
+
+Plato had a clearer idea than Aristotle of the _attractive force_
+exercised by the earth’s centre on all heavy bodies removed from
+it; for he was acquainted with the acceleration of falling bodies,
+although he did not correctly understand the cause. John Philoponus,
+the Alexandrian, probably in the sixth century, was the first who
+ascribed the movement of the heavenly bodies to a primitive impulse,
+connecting with this idea that of the fall of bodies, or the tendency
+of all substances, whether heavy or light, to reach the ground. The
+idea conceived by Copernicus, and more clearly expressed by Kepler,
+who even applied it to the ebb and flow of the ocean, received in 1666
+and 1674 a new impulse from Robert Hooke; and next Newton’s theory
+of gravitation presented the grand means of converting the whole of
+physical astronomy into a true _mechanism of the heavens_.
+
+The law of gravitation knows no exception; it accounts accurately for
+the most complex motions of the members of our own system; nay more,
+the paths of double stars, far removed from all appreciable effects
+of our portion of the universe, are in perfect accordance with its
+theory.[8]
+
+
+HEIGHT OF FALLS.
+
+The fancy of the Greeks delighted itself in wild visions of the height
+of falls. In Hesiod’s _Theogony_ it is said, speaking of the fall
+of the Titans into Tartarus, “if a brazen anvil were to fall from
+heaven nine days and nine nights long, it would reach the earth on the
+tenth.” This descent of the anvil in 777,600 seconds of time gives an
+equivalent in distance of 309,424 geographical miles (allowance being
+made, according to Galle’s calculation, for the considerable diminution
+in force of attraction at planetary distances); therefore 1½ times the
+distance of the moon from the earth. But, according to the _Iliad_,
+Hephæstus fell down to Lemnos in one day; “when but a little breath was
+still in him.”--_Note to Humboldt’s Cosmos_, vol. iii.
+
+
+RATE OF THE FALL OF BODIES.
+
+A body falls in gravity precisely 16-1/16 feet in a second, and the
+velocity increases according to the squares of the time, viz.:
+
+    In ¼ (quarter of a second) a body falls           1 foot.
+       ½ (half a second)                              4 feet.
+       1 second                                      16  ”
+       2 ditto                                       64  ”
+       3 ditto                                      144  ”
+
+The power of gravity at two miles distance from the earth is four times
+less than at one mile; at three miles nine times less, and so on. It
+goes on lessening, but is never destroyed.--_Notes in various Sciences._
+
+
+VARIETIES OF SPEED.
+
+A French scientific work states the ordinary rate to be:
+
+                                                    per second.
+    Of a man walking                                   4 feet.
+    Of a good horse in harness                        12  ”
+    Of a rein-deer in a sledge on the ice             26  ”
+    Of an English race-horse                          43  ”
+    Of a hare                                         88  ”
+    Of a good sailing ship                            19  ”
+    Of the wind                                       82  ”
+    Of sound                                        1038  ”
+    Of a 24-pounder cannon-ball                     1300  ”
+
+
+LIFTING HEAVY PERSONS.
+
+One of the most extraordinary pages in Sir David Brewster’s _Letters
+on Natural Magic_ is the experiment in which a heavy man is raised
+with the greatest facility when he is lifted up the instant that his
+own lungs, and those of the persons who raise him, are inflated with
+air. Thus the heaviest person in the party lies down upon two chairs,
+his legs being supported by the one and his back by the other. Four
+persons, one at each leg, and one at each shoulder, then try to raise
+him--the person to be raised giving two signals, by clapping his hands.
+At the first signal, he himself and the four lifters begin to draw a
+long and full breath; and when the inhalation is completed, or the
+lungs filled, the second signal is given for raising the person from
+the chair. To his own surprise, and that of his bearers, he rises with
+the greatest facility, as if he were no heavier than a feather. Sir
+David Brewster states that he has seen this inexplicable experiment
+performed more than once; and he appealed for testimony to Sir Walter
+Scott, who had repeatedly seen the experiment, and performed the part
+both of the load and of the bearer. It was first shown in England by
+Major H., who saw it performed in a large party at Venice, under the
+direction of an officer of the American navy.[9]
+
+Sir David Brewster (in a letter to _Notes and Queries_, No. 143)
+further remarks, that “the inhalation of the lifters the moment the
+effort is made is doubtless essential, and for this reason: when we
+make a great effort, either in pulling or lifting, we always fill the
+chest with air previous to the effort; and when the inhalation is
+completed, we close the _rima glottidis_ to keep the air in the lungs.
+The chest being thus kept expanded, the pulling or lifting muscles have
+received as it were a fulcrum round which their power is exerted; and
+we can thus lift the greatest weight which the muscles are capable of
+doing. When the chest collapses by the escape of the air, the lifters
+lose their muscular power; reinhalation of air by the liftee can
+certainly add nothing to the power of the lifters, or diminish his
+own weight, which is only increased by the weight of the air which he
+inhales.”
+
+
+“FORCE CAN NEITHER BE CREATED NOR DESTROYED.”
+
+Professor Faraday, in his able inquiry upon “the Conservation of
+Force,” maintains that to admit that force may be destructible, or can
+altogether disappear, would be to admit that matter could be uncreated;
+for we know matter only by its forces. From his many illustrations we
+select the following:
+
+  The indestructibility of individual matter is a most important case
+  of the Conservation of Chemical Force. A molecule has been endowed
+  with powers which give rise in it to various qualities; and those
+  never change, either in their nature or amount. A particle of
+  oxygen is ever a particle of oxygen; nothing can in the least wear
+  it. If it enters into combination, and disappears as oxygen; if it
+  pass through a thousand combinations--animal, vegetable, mineral;
+  if it lie hid for a thousand years, and then be evolved,--it is
+  oxygen with the first qualities, neither more nor less. It has
+  all its original force, and only that; the amount of force which
+  it disengaged when hiding itself, has again to be employed in a
+  reverse direction when it is set at liberty: and if, hereafter,
+  we should decompose oxygen, and find it compounded of other
+  particles, we should only increase the strength of the proof of the
+  conservation of force; for we should have a right to say of these
+  particles, long as they have been hidden, all that we could say of
+  the oxygen itself.
+
+In conclusion, he adds:
+
+  Let us not admit the destruction or creation of force without clear
+  and constant proof. Just as the chemist owes all the perfection
+  of his science to his dependence on the certainty of gravitation
+  applied by the balance, so may the physical philosopher expect to
+  find the greatest security and the utmost aid in the principle
+  of the conservation of force. All that we have that is good and
+  safe--as the steam-engine, the electric telegraph, &c.--witness to
+  that principle; it would require a perpetual motion, a fire without
+  heat, heat without a source, action without reaction, cause without
+  effect, or effect without cause, to displace it from its rank as a
+  law of nature.
+
+
+NOTHING LOST IN THE MATERIAL WORLD.
+
+“It is remarkable,” says Kobell in his _Mineral Kingdom_, “how a change
+of place, a circulation as it were, is appointed for the inanimate or
+naturally immovable things upon the earth; and how new conditions,
+new creations, are continually developing themselves in this way. I
+will not enter here into the evaporation of water, for instance from
+the widely-spreading ocean; how the clouds produced by this pass over
+into foreign lands and then fall again to the earth as rain, and how
+this wandering water is, partly at least, carried along new journeys,
+returning after various voyages to its original home: the mere
+mechanical phenomena, such as the transfer of seeds by the winds or by
+birds, or the decomposition of the surface of the earth by the friction
+of the elements, suffice to illustrate this.”
+
+
+TIME AN ELEMENT OF FORCE.
+
+Professor Faraday observes that Time is growing up daily into
+importance as an element in the exercise of Force, which he thus
+strikingly illustrates:
+
+  The earth moves in its orbit of time; the crust of the earth moves
+  in time; light moves in time; an electro-magnet requires time for
+  its charge by an electric current: to inquire, therefore, whether
+  power, acting either at sensible or insensible distances, always
+  acts in _time_, is not to be metaphysical; if it acts in time and
+  across space, it must act by physical lines of force; and our view
+  of the nature of force may be affected to the extremest degree
+  by the conclusions which experiment and observation on time may
+  supply, being perhaps finally determinable only by them. To inquire
+  after the possible time in which gravitating, magnetic, or electric
+  force is exerted, is no more metaphysical than to mark the times
+  of the hands of a clock in their progress; or that of the temple
+  of Serapis, and its ascents and descents; or the periods of the
+  occultation of Jupiter’s satellites; or that in which the light
+  comes from them to the earth. Again, in some of the known cases of
+  the action of time something happens while _the time_ is passing
+  which did not happen before, and does not continue after; it is
+  therefore not metaphysical to expect an effect in _every_ case, or
+  to endeavour to discover its existence and determine its nature.
+
+
+CALCULATION OF HEIGHTS AND DISTANCES.
+
+By the assistance of a seconds watch the following interesting
+calculations may be made:
+
+  If a traveller, when on a precipice or on the top of a building,
+  wish to ascertain the height, he should drop a stone, or any other
+  substance sufficiently heavy not to be impeded by the resistance of
+  the atmosphere; and the number of seconds which elapse before it
+  reaches the bottom, carefully noted on a seconds watch, will give
+  the height. For the stone will fall through the space of 16-1/8
+  feet during the first second, and will increase in rapidity as the
+  square of the time employed in the fall: if, therefore, 16-1/8 be
+  multiplied by the number of seconds the stone has taken to fall,
+  this product also multiplied by the same number of seconds will
+  give the height. Suppose the stone takes five seconds to reach the
+  bottom:
+
+    16-1/8 × 5 = 80-5/8 × 5 = 403-1/8, height of the precipice.
+
+  The Count Xavier de Maistre, in his _Expédition nocturne autour
+  de ma Chambre_, anxious to ascertain the exact height of his room
+  from the ground on which Turin is built, tells us he proceeded
+  as follows: “My heart beat quickly, and I just counted three
+  pulsations from the instant I dropped my slipper until I heard
+  the sound as it fell in the street, which, according to the
+  calculations made of the time taken by bodies in their accelerated
+  fall, and of that employed by the sonorous undulations of the
+  air to arrive from the street to my ear, gave the height of my
+  apartment as 94 feet 3 inches 1 tenth (French measure), supposing
+  that my heart, agitated as it was, beat 120 times in a minute.”
+
+  A person travelling may ascertain his rate of walking by the aid
+  of a slight string with a piece of lead at one end, and the use of
+  a seconds watch; the string being knotted at distances of 44 feet,
+  the 120th part of an English mile, and bearing the same proportion
+  to a mile that half a minute bears to an hour. If the traveller,
+  when going at his usual rate, drops the lead, and suffers the
+  string to slip through his hand, the number of knots which pass in
+  half a minute indicate the number of miles he walks in an hour.
+  This contrivance is similar to a _log-line_ for ascertaining a
+  ship’s rate at sea: the lead is enclosed in wood (whence the name
+  _log_), that it may float, and the divisions, which are called
+  _knots_, are measured for nautical miles. Thus, if ten knots are
+  passed in half a minute, they show that the vessel is sailing at
+  the rate of ten knots, or miles, an hour: a seconds watch would
+  here be of great service, but the half-minute sand-glass is in
+  general use.
+
+  The rapidity of a river may be ascertained by throwing in a light
+  floating substance, which, if not agitated by the wind, will move
+  with the same celerity as the water: the distance it floats in a
+  certain number of seconds will give the rapidity of the stream; and
+  this indicates the height of its source, the nature of its bottom,
+  &c.--See _Sir Howard Douglas on Bridges_. _Thomson’s Time and
+  Time-keepers._
+
+
+SAND IN THE HOUR-GLASS.
+
+It is a noteworthy fact, that the flow of Sand in the Hour-glass is
+perfectly equable, whatever may be the quantity in the glass; that is,
+the sand runs no faster when the upper half of the glass is quite full
+than when it is nearly empty. It would, however, be natural enough to
+conclude, that when full of sand it would be more swiftly urged through
+the aperture than when the glass was only a quarter full, and near the
+close of the hour.
+
+The fact of the even flow of sand may be proved by a very simple
+experiment. Provide some silver sand, dry it over or before the fire,
+and pass it through a tolerably fine sieve. Then take a tube, of any
+length or diameter, closed at one end, in which make a small hole, say
+the eighth of an inch; stop this with a peg, and fill up the tube with
+the sifted sand. Hold the tube steadily, or fix it to a wall or frame
+at any height from a table; remove the peg, and permit the sand to flow
+in any measure for any given time, and note the quantity. Then let the
+tube be emptied, and only half or a quarter filled with sand; measure
+again for a like time, and the same quantity of sand will flow: even if
+you press the sand in the tube with a ruler or stick, the flow of the
+sand through the hole will not be increased.
+
+The above is explained by the fact, that when the sand is poured into
+the tube, it fills it with a succession of conical heaps; and that all
+the weight which the bottom of the tube sustains is only that of the
+heap which _first_ falls upon it, as the succeeding heaps do not press
+downward, but only against the sides or walls of the tube.
+
+
+FIGURE OF THE EARTH.
+
+By means of a purely astronomical determination, based upon the action
+which the earth exerts on the motion of the moon, or, in other words,
+on the inequalities in lunar longitudes and latitudes, Laplace has
+shown in one single result the mean Figure of the Earth.
+
+  It is very remarkable that an astronomer, without leaving his
+  observatory, may, merely by comparing his observations with
+  mean analytical results, not only be enabled to determine with
+  exactness the size and degree of ellipticity of the earth, but
+  also its distance from the sun and moon; results that otherwise
+  could only be arrived at by long and arduous expeditions to the
+  most remote parts of both hemispheres. The moon may therefore, by
+  the observation of its movements, render appreciable to the higher
+  departments of astronomy the ellipticity of the earth, as it taught
+  the early astronomers the rotundity of our earth by means of its
+  eclipses.--_Laplace’s Expos. du Syst. du Monde._
+
+
+HOW TO ASCERTAIN THE EARTH’S MAGNITUDE.
+
+Sir John Herschel gives the following means of approximation. It
+appears by observation that two points, each ten feet above the
+surface, cease to be visible from each other over still water, and, in
+average atmospheric circumstances, at a distance of about eight miles.
+But 10 feet is the 528th part of a mile; so that half their distance,
+or four miles, is to the height of each as 4 × 528, or 2112:1, and
+therefore in the same proportion to four miles is the length of the
+earth’s diameter. It must, therefore, be equal to 4 × 2112 = 8448, or
+in round numbers, about 8000 miles, which is not very far from the
+truth.
+
+  The excess is, however, about 100 miles, or 1/80th part. As
+  convenient numbers to remember, the reader may bear in mind, that
+  in our latitude there are just as many thousands of feet in a
+  degree of the meridian as there are days in the year (365); that,
+  speaking loosely, a degree is about seventy British statute miles,
+  and a second about 100 feet; that the equatorial circumference of
+  the earth is a little less than 25,000 miles (24,899), and the
+  ellipticity or polar flattening amounts to 1/300th part of the
+  diameter.--_Outlines of Astronomy._
+
+
+MASS AND DENSITY OF THE EARTH.
+
+With regard to the determination of the Mass and Density of the Earth
+by direct experiment, we have, in addition to the deviations of the
+pendulum produced by mountain masses, the variation of the same
+instruments when placed in a mine 1200 feet in depth. The most recent
+experiments were conducted by Professor Airy, in the Harton coal-pit,
+near South Shields:[10] the oscillations of the pendulum at the bottom
+of the pit were compared with those of a clock above; the beats of the
+clock were transferred below for comparison by an electrio wire; and it
+was thus determined that a pendulum vibrating seconds at the mouth of
+the pit would gain 2¼ seconds per day at its bottom. The final result
+of the calculations depending on this experiment, which were published
+in the _Philosophical Transactions_ of 1856, gives 6·565 for the mean
+density of the earth. The celebrated Cavendish experiment, by means
+of which the density of the earth was determined by observing the
+attraction of leaden balls on each other, has been repeated in a manner
+exhibiting an astonishing amount of skill and patience by the late Mr.
+F. Baily.[11] The result of these experiments, combined with those
+previously made, gives as a mean result 5·441 as the earth’s density,
+when compared with water; thus confirming one of Newton’s astonishing
+divinations, that the mean density of the earth would be found to be
+between five and six times that of water.
+
+  Humboldt is, however, of opinion that “we know only the mass of
+  the whole earth and its mean density by comparing it with the
+  open strata, which alone are accessible to us. In the interior of
+  the earth, where all knowledge of its chemical and mineralogical
+  character fails, we are limited to as pure conjecture as in the
+  remotest bodies that revolve round the sun. We can determine
+  nothing with certainty regarding the depth at which the geological
+  strata must be supposed to be in a state of softening or of liquid
+  fusion, of the condition of fluids when heated under an enormous
+  pressure, or of the law of the increase of density from the upper
+  surface to the centre of the earth.”--_Cosmos_, vol. i.
+
+In M. Foucault’s beautiful experiment, by means of the vibration of
+a long pendulum, consisting of a heavy mass of metal suspended by a
+long wire from a strong fixed support, is demonstrated to the eye
+the rotation of the earth. The Gyroscope of the same philosopher
+is regarded not as a mere philosophical toy; but the principles of
+dynamics, by means of which it is made to demonstrate the earth’s
+rotation on its own axis, are explained with the greatest clearness.
+Thus the ingenuity of M. Foucault, combined with a profound knowledge
+of mechanics, has obtained proofs of one of the most interesting
+problems of astronomy from an unsuspected source.
+
+
+THE EARTH AND MAN COMPARED.
+
+The Earth--speaking roundly--is 8000 miles in diameter; the atmosphere
+is calculated to be fifty miles in altitude; the loftiest mountain peak
+is estimated at five miles above the level of the sea, for this height
+has never been visited by man; the deepest mine that he has formed is
+1650 feet; and his own stature does not average six feet. Therefore, if
+it were possible for him to construct a globe 800 feet--or twice the
+height of St. Paul’s Cathedral--in diameter, and to place upon any one
+point of its surface an atom of 1/4380th of an inch in diameter, and
+1/720th of an inch in height, it would correctly denote the proportion
+that man bears to the earth upon which he moves.
+
+  When by measurements, in which the evidence of the method advances
+  equally with the precision of the results, the volume of the earth
+  is reduced to the millionth part of the volume of the sun; when
+  the sun himself, transported to the region of the stars, takes
+  up a very modest place among the thousands of millions of those
+  bodies that the telescope has revealed to us; when the 38,000,000
+  of leagues which separate the earth from the sun have become, by
+  reason of their comparative smallness, a base totally insufficient
+  for ascertaining the dimensions of the visible universe; when even
+  the swiftness of the luminous rays (77,000 leagues per second)
+  barely suffices for the common valuations of science; when, in
+  short, by a chain of irresistible proofs, certain stars have
+  retired to distances that light could not traverse in less than a
+  million of years;--we feel as if annihilated by such immensities.
+  In assigning to man and to the planet that he inhabits so small a
+  position in the material world, astronomy seems really to have made
+  progress only to humble us.--_Arago._
+
+
+MEAN TEMPERATURE OF THE EARTH’S SURFACE.
+
+Professor Dove has shown, by taking at all seasons the mean of the
+temperature of points diametrically opposite to each other, that the
+mean temperature _of the whole earth’s surface_ in June considerably
+exceeds that in December. This result, which is at variance with the
+greater proximity of the sun in December, is, however, due to a totally
+different and very powerful cause,--the greater amount of land in
+that hemisphere which has its summer solstice in June (_i. e._ the
+northern); and the fact is so explained by him. The effect of land
+under sunshine is to throw heat into the general atmosphere, and to
+distribute it by the carrying power of the latter over the whole earth.
+Water is much less effective in this respect, the heat penetrating its
+depths and being there absorbed; so that the surface never acquires
+a very elevated temperature, even under the equator.--_Sir John
+Herschel’s Outlines._
+
+
+TEMPERATURE OF THE EARTH STATIONARY.
+
+Although, according to Bessel, 25,000 cubic miles of water flow in
+every six hours from one quarter of the earth to another, and the
+temperature is augmented by the ebb and flow of every tide, all
+that we know with certainty is, that the _resultant effect_ of all
+the thermal agencies to which the earth is exposed has undergone
+no perceptible change within the historic period. We owe this fine
+deduction to Arago. In order that the _date palm_ should ripen its
+fruit, the mean temperature of the place must exceed 70 deg. Fahr.;
+and, on the other hand, the _vine_ cannot be cultivated successfully
+when the temperature is 72 deg. or upwards. Hence the mean temperature
+of any place at which these two plants flourished and bore fruit must
+lie between these narrow limits, _i. e._ could not differ from 71 deg.
+Fahr. by more than a single degree. Now from the Bible we learn that
+both plants were _simultaneously_ cultivated in the central valleys
+of Palestine in the time of Moses; and its then temperature is thus
+definitively determined. It is the same at the present time; so that
+the mean temperature of this portion of the globe has not sensibly
+altered in the course of thirty-three centuries.
+
+
+THEORY OF CRYSTALLISATION.
+
+Professor Plücker has ascertained that certain crystals, in particular
+the cyanite, “point very well to the north by the magnetic power of the
+earth only. It is a true compass-needle; and more than that, you may
+obtain its declination.” Upon this Mr. Hunt remarks: “We must remember
+that this crystal, the cyanite, is a compound of silica and alumina
+only. This is the amount of experimental evidence which science has
+afforded in explanation of the conditions under which nature pursues
+her wondrous work of crystal formation. We see just sufficient of
+the operation to be convinced that the luminous star which shines in
+the brightness of heaven, and the cavern-secreted gem, are equally
+the result of forces which are known to us in only a few of their
+modifications.”--_Poetry of Science._
+
+Gay Lussac first made the remark, that a crystal of potash-alum,
+transferred to a solution of ammonia-alum, continued to increase
+without its form being modified, and might thus be covered with
+alternate layers of the two alums, preserving its regularity and proper
+crystalline figure. M. Beudant afterwards observed that other bodies,
+such as the sulphates of iron and copper, might present themselves
+in crystals of the same form and angles, although the form was not a
+simple one, like that of alum. But M. Mitscherlich first recognised
+this correspondence in a sufficient number of cases to prove that it
+was a general consequence of similarity of composition in different
+bodies.--_Graham’s Elements of Chemistry._
+
+
+IMMENSE CRYSTALS.
+
+Crystals are found in the most microscopic character, and of an
+exceedingly large size. A crystal of quartz at Milan is three feet and
+a quarter long, and five feet and a half in circumference: its weight
+is 870 pounds. Beryls have been found in New Hampshire measuring four
+feet in length.--_Dana._
+
+
+VISIBLE CRYSTALLISATION.
+
+Professor Tyndall, in a lecture delivered by him at the Royal
+Institution, London, on the properties of Ice, gave the following
+interesting illustration of crystalline force. By perfectly cleaning a
+piece of glass, and placing on it a film of a solution of chloride of
+ammonium or sal ammoniac, the action of crystallisation was shown to
+the whole audience. The glass slide was placed in a microscope, and the
+electric light passing through it was concentrated on a white disc. The
+image of the crystals, as they started into existence, and shot across
+the disc in exquisite arborescent and symmetrical forms, excited the
+admiration of every one. The lecturer explained that the heat, causing
+the film of moisture to evaporate, brought the particles of salt
+sufficiently near to exercise the crystalline force, the result being
+the beautiful structure built up with such marvellous rapidity.
+
+
+UNION OF MINERALOGY AND GEOMETRY.
+
+It is a peculiar characteristic of minerals, that while plants and
+animals differ in various regions of the earth, mineral matter of the
+same character may be discovered in any part of the world,--at the
+Equator or towards the Poles; at the summit of the loftiest mountains,
+and in works far beneath the level of the sea. The granite of Australia
+does not necessarily differ from that of the British islands; and ores
+of the same metals (the proper geological conditions prevailing) may
+be found of the same general character in all regions. Climate and
+geographical position have no influence on the composition of mineral
+substances.
+
+This uniformity may, in some measure, have induced philosophers to
+seek its extension to the forms of crystallography. About 1760 (says
+Mr. Buckle, in his _History of Civilization_), Romé de Lisle set the
+first example of studying crystals, according to a scheme so large as
+to include all the varieties of their primary forms, and to account
+for their irregularities and the apparent caprice with which they
+were arranged. In this investigation he was guided by the fundamental
+assumption, that what is called an irregularity is in truth perfectly
+regular, and that the operations of nature are invariable. Haüy applied
+this great idea to the almost innumerable forms in which minerals
+crystallise. He thus achieved a complete union between mineralogy and
+geometry; and, bringing the laws of space to bear on the molecular
+arrangements of matter, he was able to penetrate into the intimate
+structure of crystals. By this means he proved that the secondary
+forms of all crystals are derived from their primary forms by a
+regular process of decrement; and that when a substance is passing
+from a liquid to a solid state, its particles cohere, according to a
+scheme which provides for every possible change, since it includes
+even those subsequent layers which alter the ordinary type of the
+crystal, by disturbing its natural symmetry. To ascertain that such
+violations of symmetry are susceptible of mathematical calculation,
+was to make a vast addition to our knowledge; and, by proving that
+even the most uncouth and singular forms are the natural results of
+their antecedents, Haüy laid the foundation of what may be called the
+pathology of the inorganic world. However paradoxical such a notion may
+appear, it is certain that symmetry is to crystals what health is to
+animals; so that an irregularity of shape in the first corresponds with
+an appearance of disease in the second.--See _Hist. Civilization_, vol.
+i.
+
+
+REPRODUCTIVE CRYSTALLISATION.
+
+The general belief that only organic beings have the power of
+reproducing lost parts has been disproved by the experiments of Jordan
+on crystals. An octohedral crystal of alum was fractured; it was then
+replaced in a solution, and after a few days its injury was seen to be
+repaired. The whole crystal had of course increased in size; but the
+increase on the broken surface had been so much greater that a perfect
+octohedral form was regained.--_G. H. Lewes._
+
+This remarkable power possessed by crystals, in common with animals,
+of repairing their own injuries had, however, been thus previously
+referred to by Paget, in his _Pathology_, confirming the experiments
+of Jordan on this curious subject: “The ability to repair the damages
+sustained by injury ... is not an exclusive property of living beings;
+for even crystals will repair themselves when, after pieces have been
+broken from them, they are placed in the same conditions in which they
+were first formed.”
+
+
+GLASS BROKEN BY SAND.
+
+In some glass-houses the workmen show glass which has been cooled in
+the open air; on this they let fall leaden bullets without breaking the
+glass. They afterwards desire you to let a few grains of sand fall upon
+the glass, by which it is broken into a thousand pieces. The reason
+of this is, that the lead does not scratch the surface of the glass;
+whereas the sand, being sharp and angular, scratches it sufficiently to
+produce the above effect.
+
+
+
+
+Sound and Light.
+
+
+SOUNDING SAND.
+
+Mr. Hugh Miller, the geologist, when in the island of Eigg, in the
+Hebrides, observed that a musical sound was produced when he walked
+over the white dry sand of the beach. At each step the sand was driven
+from his footprint, and the noise was simultaneous with the scattering
+of the sand; the cause being either the accumulated vibrations of
+the air when struck by the driven sand, or the accumulated sounds
+occasioned by the mutual impact of the particles of sand against each
+other. If a musket-ball passing through the air emits a whistling note,
+each individual particle of sand must do the same, however faint be
+the note which it yields; and the accumulation of these infinitesimal
+vibrations must constitute an audible sound, varying with the number
+and velocity of the moving particles. In like manner, if two plates of
+silex or quartz, which are but crystals of sand, give out a musical
+sound when mutually struck, the impact or collision of two minute
+crystals or particles of sand must do the same, in however inferior a
+degree; and the union of all these sounds, though singly imperceptible,
+may constitute the musical notes of “the Mountain of the Bell” in
+Arabia Petræa, or the lesser sounds of the trodden sea-beach of
+Eigg.--_North-British Review_, No. 5.
+
+
+INTENSITY OF SOUND IN RAREFIED AIR.
+
+The experiences during ascents of the highest mountains are
+contradictory. Saussure describes the sounds on the top of Mont Blanc
+as remarkably weak: a pistol-shot made no more noise than an ordinary
+Chinese cracker, and the popping of a bottle of champagne was scarcely
+audible. Yet Martius, in the same situation, was able to distinguish
+the voices of the guides at a distance of 1340 feet, and to hear the
+tapping of a lead pencil upon a metallic surface at a distance of from
+75 to 100 feet.
+
+MM Wertheim and Breguet have propagated sound over the wire of an
+electric telegraph at the rate of 11,454 feet per second.
+
+
+DISTANCE AT WHICH THE HUMAN VOICE MAY BE HEARD.
+
+Experience shows that the human voice, under favourable circumstances,
+is capable of filling a larger space than was ever probably enclosed
+within the walls of a single room. Lieutenant Foster, on Parry’s third
+Arctic expedition, found that he could converse with a man across the
+harbour of Port Bowen, a distance of 6696 feet, or about one mile and a
+quarter. Dr. Young records that at Gibraltar the human voice has been
+heard at a distance of ten miles. If sound be prevented from spreading
+and losing itself in the air, either by a pipe or an extensive flat
+surface, as a wall or still water, it may be conveyed to a great
+distance. Biot heard a flute clearly through a tube of cast-iron (the
+water-pipes of Paris) 3120 feet long: the lowest whisper was distinctly
+heard; indeed, the only way not to be heard was not to speak at all.
+
+
+THE ROAR OF NIAGARA.
+
+The very nature of the sound of running water pronounces its origin
+to be the bursting of bubbles: the impact of water against water is a
+comparatively subordinate cause, and could never of itself occasion the
+murmur of a brook; whereas, in streams which Dr. Tyndall has examined,
+he, in all cases where a ripple was heard, discovered bubbles caused by
+the broken column of water. Now, were Niagara continuous, and without
+lateral vibration, it would be as silent as a cataract of ice. In all
+probability, it has its “contracted sections,” after passing which
+it is broken into detached masses, which, plunging successively upon
+the air-bladders formed by their precursors, suddenly liberate their
+contents, and thus create _the thunder of the waterfall_.
+
+
+FIGURES PRODUCED BY SOUND.
+
+Stretch a sheet of wet paper over the mouth of a glass tumbler which
+has a footstalk, and glue or paste the paper at the edges. When the
+paper is dry, strew dry sand thinly upon its surface. Place the tumbler
+on a table, and hold immediately above it, and parallel to the paper,
+a plate of glass, which you also strew with sand, having previously
+rubbed the edges smooth with emery powder. Draw a violin-bow along any
+part of the edges; and as the sand upon the glass is made to vibrate,
+it will form various figures, which will be accurately imitated by the
+sand upon the paper; or if a violin or flute be played within a few
+inches of the paper, they will cause the sand upon its surface to form
+regular lines and figures.
+
+
+THE TUNING-FORK A FLUTE-PLAYER.
+
+Take a common tuning-fork, and on one of its branches fasten with
+sealing-wax a circular piece of card of the size of a small wafer, or
+sufficient nearly to cover the aperture of a pipe, as the sliding of
+the upper end of a flute with the mouth stopped: it may be tuned in
+unison with the loaded tuning-fork by means of the movable stopper or
+card, or the fork may be loaded till the unison is perfect. Then set
+the fork in vibration by a blow on the unloaded branch, and hold the
+card closely over the mouth of the pipe, as in the engraving, when a
+note of surprising clearness and strength will be heard. Indeed a flute
+may be made to “speak” perfectly well, by holding close to the opening
+a vibrating tuning-fork, while the fingering proper to the note of the
+fork is at the same time performed.
+
+
+THEORY OF THE JEW’S HARP.
+
+If you cause the tongue of this little instrument to vibrate, it will
+produce a very low sound; but if you place it before a cavity (as the
+mouth) containing a column of air, which vibrates much faster, but
+in the proportion of any simple multiple, it will then produce other
+higher sounds, dependent upon the reciprocation of that portion of
+the air. Now the bulk of air in the mouth can be altered in its form,
+size, and other circumstances, so as to produce by reciprocation many
+different sounds; and these are the sounds belonging to the Jew’s Harp.
+
+A proof of this fact has been given by Mr. Eulenstein, who fitted into
+a long metallic tube a piston, which being moved, could be made to
+lengthen or shorten the efficient column of air within at pleasure. A
+Jew’s Harp was then so fixed that it could be made to vibrate before
+the mouth of the tube, and it was found that the column of air produced
+a series of sounds, according as it was lengthened or shortened; a
+sound being produced whenever the length of the column was such that
+its vibrations were a multiple of those of the Jew’s Harp.
+
+
+SOLAR AND ARTIFICIAL LIGHT COMPARED.
+
+The most intensely ignited solid (produced by the flame of Lieutenant
+Drummond’s oxy-hydrogen lamp directed against a surface of chalk)
+appears only as black spots on the disc of the sun, when held between
+it and the eye; or in other words, Drummond’s light is to the light of
+the sun’s disc as 1 to 146. Hence we are doubly struck by the felicity
+with which Galileo, as early as 1612, by a series of conclusions on
+the smallness of the distance from the sun at which the disc of Venus
+was no longer visible to the naked eye, arrived at the result that
+the blackest nucleus of the sun’s spots was more luminous than the
+brightest portions of the full moon. (See “The Sun’s Light compared
+with Terrestrial Lights,” in _Things not generally Known_, pp. 4, 5.)
+
+
+SOURCE OF LIGHT.
+
+Mr. Robert Hunt, in a lecture delivered by him at the Russell
+Institution, “On the Physics of a Sunbeam,” mentions some experiments
+by Lord Brougham on the sunbeam, in which, by placing the edge of a
+sharp knife just within the limit of the light, the ray was inflected
+from its previous direction, and coloured red; and when another knife
+was placed on the opposite side, it was deflected, and the colour was
+blue. These experiments (says Mr. Hunt) seem to confirm Sir Isaac
+Newton’s theory, that light is a fluid emitted from the sun.
+
+
+THE UNDULATORY SCALE OF LIGHT.
+
+The white light of the sun is well known to be composed of several
+coloured rays; or rather, according to the theory of undulations, when
+the rate at which a ray vibrates is altered, a different sensation
+is produced upon the optic nerve. The analytical examination of
+this question shows that to produce a red colour the ray of light
+must give 37,640 undulations in an inch, and 458,000,000,000,000 in
+a second. Yellow light requires 44,000 undulations in an inch, and
+535,000,000,000,000 in a second; whilst the effect of blue results from
+51,110 undulations within an inch, and 622,000,000,000,000 of waves in
+a second of time.--_Hunt’s Poetry of Science._
+
+
+VISIBILITY OF OBJECTS.
+
+In terrestrial objects, the form, no less than the modes of
+illumination, determines the magnitude of the smallest angle of vision
+for the naked eye. Adams very correctly observed that a long and
+slender staff can be seen at a much greater distance than a square
+whose sides are equal to the diameter of the staff. A stripe may be
+distinguished at a greater distance than a spot, even when both are of
+the same diameter.
+
+The _minimum_ optical visual angle at which terrestrial objects can
+be recognised by the naked eye has been gradually estimated lower and
+lower, from the time when Robert Hooke fixed it exactly at a full
+minute, and Tobias Meyer required 34″ to perceive a black speck on
+white paper, to the period of Leuwenhoeck’s experiments with spiders’
+threads, which are visible to ordinary sight at an angle of 4″·7. In
+Hueck’s most accurate experiments on the problem of the movement of
+the crystalline lens, white lines on a black ground were seen at an
+angle of 1″·2; a spider’s thread at 0″·6; and a fine glistening wire at
+scarcely 0″·2.
+
+  Humboldt, when at Chillo, near Quito, where the crests of the
+  volcano of Pichincha lay at a horizontal distance of 90,000 feet,
+  was much struck by the circumstance that the Indians standing near
+  distinguished the figure of Bonpland (then on an expedition to the
+  volcano), as a white point moving on the black basaltic sides of
+  the rock, sooner than Humboldt could discover him with a telescope.
+  Bonpland was enveloped in a white cotton poncho: assuming the
+  breadth across the shoulders to vary from three to five feet,
+  according as the mantle clung to the figure or fluttered in the
+  breeze, and judging from the known distance, the angle at which the
+  moving object could be distinctly seen varied from 7″ to 12″. White
+  objects on a black ground are, according to Hueck, distinguished at
+  a greater distance than black objects on a white ground.
+
+  Gauss’s heliotrope light has been seen with the naked eye reflected
+  from the Brocken on Hobenhagen at a distance of about 227,000 feet,
+  or more than 42 miles; being frequently visible at points in which
+  the apparent breadth of a three-inch mirror was only 0″·43.
+
+
+THE SMALLEST BRIGHT BODIES.
+
+Ehrenberg has found from experiments on the dust of diamonds, that
+a diamond superficies of 1/100th of a line in diameter presents a
+much more vivid light to the naked eye than one of quicksilver of the
+same diameter. On pressing small globules of quicksilver on a glass
+micrometer, he easily obtained smaller globules of the 1/100th to the
+1/2000th of a line in diameter. In the sunshine he could only discern
+the reflection of light, and the existence of such globules as were
+1/300th of a line in diameter, with the naked eye. Smaller ones did
+not affect his eye; but he remarked that the actual bright part of the
+globule did not amount to more than 1/900th of a line in diameter.
+Spider threads of 1/2000th in diameter were still discernible from
+their lustre. Ehrenberg concludes that there are in organic bodies
+magnitudes capable of direct proof which are in diameter 1/100000 of a
+line; and others, that can be indirectly proved, which may be less than
+a six-millionth part of a Parisian line in diameter.
+
+
+VELOCITY OF LIGHT.
+
+It is scarcely possible so to strain the imagination as to conceive
+the Velocity with which Light travels. “What mere assertion will make
+any man believe,” asks Sir John Herschel, “that in one second of time,
+in one beat of the pendulum of a clock, a ray of light travels over
+192,000 miles; and would therefore perform the tour of the world in
+about the same time that it requires to wink with our eyelids, and in
+much less time than a swift runner occupies in taking a single stride?”
+Were a cannon-ball shot directly towards the sun, and were it to
+maintain its full speed, it would be twenty years in reaching it; and
+yet light travels through this space in seven or eight minutes.
+
+The result given in the _Annuaire_ for 1842 for the velocity of light
+in a second is 77,000 leagues, which corresponds to 215,834 miles;
+while that obtained at the Pulkowa Observatory is 189,746 miles.
+William Richardson gives as the result of the passage of light from the
+sun to the earth 8´ 19″·28, from which we obtain a velocity of 215,392
+miles in a second.--_Memoirs of the Astronomical Society_, vol. iv.
+
+In other words, light travels a distance equal to eight times the
+circumference of the earth between two beats of a clock. This is a
+prodigious velocity; but the measure of it is very certain.--_Professor
+Airy._
+
+The navigator who has measured the earth’s circuit by his hourly
+progress, or the astronomer who has paced a degree of the meridian, can
+alone form a clear idea of velocity, when we tell him that light moves
+through a space equal to the circumference of the earth in _the eighth
+part of a second_--in the twinkling of an eye.
+
+  Could an observer, placed in the centre of the earth, see this
+  moving light, as it describes the earth’s circumference, it would
+  appear a luminous ring; that is, the impression of the light at the
+  commencement of its journey would continue on the retina till the
+  light had completed its circuit. Nay, since the impression of light
+  continues longer than the _fourth_ part of a second, _two_ luminous
+  rings would be seen, provided the light made _two_ rounds of the
+  earth, and in paths not coincident.
+
+
+APPARATUS FOR THE MEASUREMENT OF LIGHT.
+
+Humboldt enumerates the following different methods adopted for the
+Measurement of Light: a comparison of the shadows of artificial lights,
+differing in numbers and distance; diaphragms; plane-glasses of
+different thickness and colour; artificial stars formed by reflection
+on glass spheres; the juxtaposition of two seven-feet telescopes,
+separated by a distance which the observer could pass in about a
+second; reflecting instruments in which two stars can be simultaneously
+seen and compared, when the telescope has been so adjusted that the
+star gives two images of like intensity; an apparatus having (in
+front of the object-glass) a mirror and diaphragms, whose rotation
+is measured on a ring; telescopes with divided object-glasses, on
+either half of which the stellar light is received through a prism;
+astrometers, in which a prism reflects the image of the moon or
+Jupiter, and concentrates it through a lens at different distances into
+a star more or less bright.--_Cosmos_, vol. iii.
+
+
+HOW FIZEAU MEASURED THE VELOCITY OF LIGHT.
+
+This distinguished physicist has submitted the Velocity of Light
+to terrestrial measurement by means of an ingeniously constructed
+apparatus, in which artificial light (resembling stellar light),
+generated from oxygen and hydrogen, is made to pass back, by means of
+a mirror, over a distance of 28,321 feet to the same point from which
+it emanated. A disc, having 720 teeth, which made 12·6 rotations in a
+second, alternately obscured the ray of light and allowed it to be seen
+between the teeth on the margin. It was supposed, from the marking of
+a counter, that the artificial light traversed 56,642 feet, or the
+distance to and from the stations, in 1/1800th part of a second, whence
+we obtain a velocity of 191,460 miles in a second.[12] This result
+approximates most closely to Delambre’s (which was 189,173 miles), as
+obtained from Jupiter’s satellites.
+
+  The invention of the rotating mirror is due to Wheatstone, who made
+  an experiment with it to determine the velocity of the propagation
+  of the discharge of a Leyden battery. The most striking application
+  of the idea was made by Fizeau and Foucault, in 1853, in carrying
+  out a proposition made by Arago, soon after the invention of the
+  mirror: we have here determined in a distance of twelve feet no
+  less than the velocity with which light is propagated, which is
+  known to be nearly 200,000 miles a second; the distance mentioned
+  corresponds therefore to the 77-millionth part of a second. The
+  object of these measurements was to compare the velocity of light
+  in air with its velocity in water; which, when the length is
+  greater, is not sufficiently transparent. The most complete optical
+  and mechanical aids are here necessary: the mirror of Foucault
+  made from 600 to 800 revolutions in a second, while that of Fizeau
+  performed 1200 to 1500 in the same time.--_Prof. Helmholtz on the
+  Methods of Measuring very small Portions of Time._
+
+
+WHAT IS DONE BY POLARISATION OF LIGHT.
+
+Malus, in 1808, was led by a casual observation of the light of the
+setting sun, reflected from the windows of the Palais de Luxembourg,
+at Paris, to investigate more thoroughly the phenomena of double
+refraction, of ordinary and of chromatic polarisation, of interference
+and of diffraction of light. Among his results may be reckoned the
+means of distinguishing between direct and reflected light; the power
+of penetrating, as it were, into the constitution of the body of
+the sun and of its luminous envelopes; of measuring the pressure of
+atmospheric strata, and even the smallest amount of water they contain;
+of ascertaining the depths of the ocean and its rocks by means of
+a tourmaline plate; and in accordance with Newton’s prediction, of
+comparing the chemical composition of several substances with their
+optical effects.
+
+  Arago, in a letter to Humboldt, states that by the aid of his
+  polariscope, he discovered, before 1820, that the light of all
+  terrestrial objects in a state of incandescence, whether they be
+  solid or liquid, is natural, so long as it emanates from the object
+  in perpendicular rays. On the other hand, if such light emanate
+  at an acute angle, it presents manifest proofs of polarisation.
+  This led M. Arago to the remarkable conclusion, that light is not
+  generated on the surface of bodies only, but that some portion is
+  actually engendered within the substance itself, even in the case
+  of platinum.
+
+A ray of light which reaches our eyes after traversing many millions
+of miles, from, the remotest regions of heaven, announces, as it were
+of itself, in the polariscope, whether it is reflected or refracted,
+whether it emanates from a solid or fluid or gaseous body; it announces
+even the degree of its intensity.--_Humboldt’s Cosmos_, vols. i. and ii.
+
+
+MINUTENESS OF LIGHT.
+
+There is something wonderful, says Arago, in the experiments which have
+led natural philosophers legitimately to talk of the different sides of
+a ray of light; and to show that millions and millions of these rays
+can simultaneously pass through the eye of a needle without interfering
+with each other!
+
+
+THE IMPORTANCE OF LIGHT.
+
+Light affects the respiration of animals just as it affects the
+respiration of plants. This is novel doctrine, but it is demonstrable.
+In the day-time we expire more carbonic acid than during the night; a
+fact known to physiologists, who explain it as the effect of sleep: but
+the difference is mainly owing to the presence or absence of sunlight;
+for sleep, as sleep, _increases_, instead of diminishing, the amount
+of carbonic acid expired, and a man sleeping will expire more carbonic
+acid than if he lies quietly awake under the same conditions of light
+and temperature; so that if less is expired during the night than
+during the day, the reason cannot be sleep, but the absence of light.
+Now we understand why men are sickly and stunted who live in narrow
+streets, alleys, and cellars, compared with those who, under similar
+conditions of poverty and dirt, live in the sunlight.--_Blackwood’s
+Edinburgh Magazine_, 1858.
+
+  The influence of light on the colours of organised creation is well
+  shown in the sea. Near the shores we find seaweeds of the most
+  beautiful hues, particularly on the rocks which are left dry by
+  the tides; and the rich tints of the actiniæ which inhabit shallow
+  water must often have been observed. The fishes which swim near the
+  surface are also distinguished by the variety of their colours,
+  whereas those which live at greater depths are gray, brown, or
+  black. It has been found that after a certain depth, where the
+  quantity of light is so reduced that a mere twilight prevails, the
+  inhabitants of the ocean become nearly colourless.--_Hunt’s Poetry
+  of Science._
+
+
+ACTION OF LIGHT ON MUSCULAR FIBRES.
+
+That light is capable of acting on muscular fibres, independently
+of the influence of the nerves, was mentioned by several of the old
+anatomists, but repudiated by later authorities. M. Brown Séquard has,
+however, proved to the Royal Society that some portions of muscular
+fibre--the iris of the eye, for example--are affected by light
+independently of any reflex action of the nerves, thereby confirming
+former experiences. The effect is produced by the illuminating rays
+only, the chemical and heat rays remaining neutral. And not least
+remarkable is the fact, that the iris of an eel showed itself
+susceptible of the excitement _sixteen days after the eyes were removed
+from the creature’s head_. So far as is yet known, this muscle is the
+only one on which light thus takes effect.--_Phil. Trans. 1857._
+
+
+LIGHT NIGHTS.
+
+It is not possible, as well-attested facts prove, perfectly to explain
+the operations at work in the much-contested upper boundaries of
+our atmosphere. The extraordinary lightness of whole nights in the
+year 1831, during which small print might be read at midnight in
+the latitudes of Italy and the north of Germany, is a fact directly
+at variance with all that we know, according to the most recent and
+acute researches on the crepuscular theory and the height of the
+atmosphere.--_Biot._
+
+
+PHOSPHORESCENCE OF PLANTS.
+
+Mr. Hunt recounts these striking instances. The leaves of the _œnothera
+macrocarpa_ are said to exhibit phosphoric light when the air is
+highly charged with electricity. The agarics of the olive-grounds of
+Montpelier too have been observed to be luminous at night; but they
+are said to exhibit no light, even in darkness, _during the day_. The
+subterranean passages of the coal-mines near Dresden are illuminated by
+the phosphorescent light of the _rhizomorpha phosphoreus_, a peculiar
+fungus. On the leaves of the Pindoba palm grows a species of agaric
+which is exceedingly luminous at night; and many varieties of the
+lichens, creeping along the roofs of caverns, lend to them an air of
+enchantment by the soft and clear light which they diffuse. In a small
+cave near Penryn, a luminous moss is abundant; it is also found in the
+mines of Hesse. According to Heinzmann, the _rhizomorpha subterranea_
+and _aidulæ_ are also phosphorescent.--See _Poetry of Science_.
+
+
+PHOSPHORESCENCE OF THE SEA.
+
+By microscopic examination of the myriads of minute insects which cause
+this phenomenon, no other fact has been elicited than that they contain
+a fluid which, when squeezed out, leaves a train of light upon the
+surface of the water. The creatures appear almost invariably on the eve
+of some change of weather, which would lead us to suppose that their
+luminous phenomena must be connected with electrical excitation; and of
+this Mr. C. Peach of Fowey has furnished the most satisfactory proofs
+yet obtained.[13]
+
+
+LIGHT FROM THE JUICE OF A PLANT.
+
+In Brazil has been observed a plant, conjectured to be an Euphorbium,
+very remarkable for the light which it yields when cut. It contains a
+milky juice, which exudes as soon as the plant is wounded, and appears
+luminous for several seconds.
+
+
+LIGHT FROM FUNGUS.
+
+Phosphorescent funguses have been found in Brazil by Mr. Gardner,
+growing on the decaying leaves of a dwarf palm. They vary from one to
+two inches across, and the whole plant gives out at night a bright
+phosphorescent light, of a pale greenish hue, similar to that emitted
+by fire-flies and phosphorescent marine animals. The light given out by
+a few of these fungi in a dark room is sufficient to read by. A very
+large phosphorescent species is occasionally found in the Swan River
+colony.
+
+
+LIGHT FROM BUTTONS.
+
+Upon highly polished gilt buttons no figure whatever can be seen by the
+most careful examination; yet, when they are made to reflect the light
+of the sun or of a candle upon a piece of paper held close to them,
+they give a beautiful geometrical figure, with ten rays issuing from
+the centre, and terminating in a luminous rim.
+
+
+COLOURS OF SCRATCHES.
+
+An extremely fine scratch on a well-polished surface may be regarded as
+having a concave, cylindrical, or at least a curved surface, capable of
+reflecting light in all directions; this is evident, for it is visible
+in all directions. Hence a single scratch or furrow in a surface may
+produce colours by the interference of the rays reflected from its
+opposite edges. Examine a spider’s thread in the sunshine, and it will
+gleam with vivid colours. These may arise from a similar cause; or from
+the thread itself, as spun by the animal, consisting of several threads
+agglutinated together, and thus presenting, not a cylindrical, but a
+furrowed surface.
+
+
+MAGIC BUST.
+
+Sir David Brewster has shown how the rigid features of a white bust
+may be made to move and vary their expression, sometimes smiling and
+sometimes frowning, by moving rapidly in front of the bust a bright
+light, so as to make the lights and shadows take every possible
+direction and various degrees of intensity; and if the bust be placed
+before a concave mirror, its image may be made to do still more when it
+is cast upon wreaths of smoke.
+
+
+COLOURS HIT MOST FREQUENTLY DURING BATTLE.
+
+It would appear from numerous observations that soldiers are hit
+during battle according to the colour of their dress in the following
+order: red is the most fatal colour; the least fatal, Austrian gray.
+The proportions are, red, 12; rifle-green, 7; brown, 6; Austrian
+bluish-gray, 5.--_Jameson’s Journal_, 1853.
+
+
+TRANSMUTATION OF TOPAZ.
+
+Yellow topazes may be converted into pink by heat; but it is a mistake
+to suppose that in the process the yellow colour is changed into pink:
+the fact is, that one of the pencils being yellow and the other pink,
+the yellow is discharged by heat, thus leaving the pink unimpaired.
+
+
+COLOURS AND TINTS.
+
+M. Chevreul, the _Directeur des Gobelins_, has presented to the French
+Academy a plan for a universal chromatic scale, and a methodical
+classification of all imaginable colours. Mayer, a professor at
+Göttingen, calculated that the different combinations of primitive
+colours produced 819 different tints; but M. Chevreul established not
+less than 14,424, all very distinct and easily recognised,--all of
+course proceeding from the three primitive simple colours of the solar
+spectrum, red, yellow, and blue. For example, he states that in the
+violet there are twenty-eight colours, and in the dahlia forty-two.
+
+
+OBJECTS REALLY OF NO COLOUR.
+
+A body appears to be of the colour which it reflects; as we see it only
+by reflected rays, it can but appear of the colour of those rays. Thus
+grass is green because it absorbs all except the green rays. Flowers,
+in the same manner, reflect the various colours of which they appear
+to us: the rose, the red rays; the violet, the blue; the daffodil,
+the yellow, &c. But these are not the permanent colours of the grass
+and flowers; for wherever you see these colours, the objects must be
+illuminated; and light, from whatever source it proceeds, is of the
+same nature, composed of the various coloured rays which paint the
+grass, the flowers, and every coloured object in nature. Objects in
+the dark have no colour, or are black, which is the same thing. You
+can never see objects without light. Light is composed of colours,
+therefore there can be no light without colours; and though every
+object is black or without colour in the dark, it becomes coloured as
+soon as it becomes visible.
+
+
+THE DIORAMA--WHY SO PERFECT AN ILLUSION.
+
+Because when an object is viewed at so great a distance that the
+optic axes of both eyes are sensibly parallel when directed towards
+it, the perspective projections of it, seen by each eye separately,
+are similar; and the appearance to the two eyes is precisely the same
+as when the object is seen by one eye only. There is, in such case,
+no difference between the visual appearance of an object in relief
+and its perspective projection on a plane surface; hence pictorial
+representations of distant objects, when those circumstances which
+would prevent or disturb the illusion are carefully excluded, may be
+rendered such perfect resemblances of the objects they are intended to
+represent as to be mistaken for them. The Diorama is an instance of
+this.--_Professor Wheatstone_; _Philosophical Transactions_, 1838.
+
+
+CURIOUS OPTICAL EFFECTS AT THE CAPE.
+
+Sir John Herschel, in his observatory at Feldhausen, at the base of
+the Table Mountain, witnessed several curious optical effects, arising
+from peculiar conditions of the atmosphere incident to the climate of
+the Cape. In the hot season “the nights are for the most part superb;”
+but occasionally, during the excessive heat and dryness of the sandy
+plains, “the optical tranquillity of the air” is greatly disturbed.
+In some cases, the images of the stars are violently dilated into
+nebular balls or puffs of 15′ in diameter; on other occasions they
+form “soft, round, quiet pellets of 3′ or 4′ diameter,” resembling
+planetary nebulæ. In the cooler months the tranquillity of the image
+and the sharpness of vision are such, that hardly any limit is set
+to magnifying power but that which arises from the aberration of the
+specula. On occasions like these, optical phenomena of extraordinary
+splendour are produced by viewing a bright star through a diaphragm
+of cardboard or zinc pierced in regular patterns of circular holes by
+machinery: these phenomena surprise and delight every person that sees
+them. When close double stars are viewed with the telescope, with a
+diaphragm in the form of an equilateral triangle, the discs of the two
+stars, which are exact circles, have a clearness and perfection almost
+incredible.
+
+
+THE TELESCOPE AND THE MICROSCOPE.
+
+So singular is the position of the Telescope and the Microscope among
+the great inventions of the age, that no other process but that which
+they embody could make the slightest approximation to the secrets which
+they disclose. The steam-engine might have been imperfectly replaced
+by an air or an ether-engine; and a highly elastic fluid might have
+been, and may yet be, found, which shall impel the “rapid car,” or
+drag the merchant-ship over the globe. The electric telegraph, now so
+perfect and unerring, might have spoken to us in the rude “language
+of chimes;” or sound, in place of electricity, might have passed along
+the metallic path, and appealed to the ear in place of the eye. For
+the printing-press and the typographic art might have been found a
+substitute, however poor, in the lithographic process; and knowledge
+might have been widely diffused by the photographic printing powers
+of the sun, or even artificial light. But without the telescope and
+the microscope, the human eye would have struggled in vain to study
+the worlds beyond our own, and the elaborate structures of the organic
+and inorganic creation could never have been revealed.--_North-British
+Review_, No. 50.
+
+
+INVENTION OF THE MICROSCOPE.
+
+The earliest magnifying lens of which we have any knowledge was one
+rudely made of rock-crystal, which Mr. Layard found, among a number
+of glass bowls, in the north-west palace of Nimroud; but no similar
+lens has been found or described to induce us to believe that the
+microscope, either single or compound, was invented and used as an
+instrument previous to the commencement of the seventeenth century.
+In the beginning of the first century, however, Seneca alludes to the
+magnifying power of a glass globe filled with water; but as he only
+states that it made small and indistinct letters appear larger and more
+distinct, we cannot consider such a casual remark as the invention of
+the single microscope, though it might have led the observer to try the
+effect of smaller globes, and thus obtain magnifying powers sufficient
+to discover phenomena otherwise invisible.
+
+Lenses of glass were undoubtedly in existence at the time of Pliny;
+but at that period, and for many centuries afterwards, they appear
+to have been used only as burning or as reading glasses; and no
+attempt seems to have been made to form them of so small a size as
+to entitle them to be regarded even as the precursors of the single
+microscope.--_North-British Review_, No. 50.
+
+  The _rock-crystal lens_ found at Nineveh was examined by Sir
+  David Brewster. It was not entirely circular in its aperture. Its
+  general form was that of a plano-convex lens, the plane side having
+  been formed of one of the original faces of the six-sided crystal
+  quartz, as Sir David ascertained by its action on polarised light:
+  this was badly polished and scratched. The convex face of the lens
+  had not been ground in a dish-shaped tool, in the manner in which
+  lenses are now formed, but was shaped on a lapidary’s wheel, or in
+  some such manner. Hence it was unequally thick; but its extreme
+  thickness was 2/10ths of an inch, its focal length being 4½ inches.
+  It had twelve remains of cavities, which had originally contained
+  liquids or condensed gases. Sir David has assigned reasons why this
+  could not be looked upon as an ornament, but a true optical lens.
+  In the same ruins were found some decomposed glass.
+
+
+HOW TO MAKE THE FISH-EYE MICROSCOPE.
+
+Very good microscopes may be made with the crystalline lenses of
+fish, birds, and quadrupeds. As the lens of fishes is spherical or
+spheroidal, it is absolutely necessary, previous to its use, to
+determine its optical axis and the axis of vision of the eye from which
+it is taken, and place the lens in such a manner that its axis is a
+continuation of the axis of our own eye. In no other direction but this
+is the albumen of which the lens consists symmetrically disposed in
+laminæ of equal density round a given line, which is the axis of the
+lens; and in no other direction does the gradation of density, by which
+the spherical aberration is corrected, preserve a proper relation to
+the axis of vision.
+
+  When the lens of any small fish, such as a minnow, a par, or trout,
+  has been taken out, along with the adhering vitreous humour, from
+  the eye-ball by cutting the sclerotic coat with a pair of scissors,
+  it should be placed upon a piece of fine silver-paper previously
+  freed from its minute adhering fibres. The absorbent nature of
+  the paper will assist in removing all the vitreous humour from
+  the lens; and when this is carefully done, by rolling it about
+  with another piece of silver-paper, there will still remain,
+  round or near the equator of the lens, a black ridge, consisting
+  of the processes by which it was suspended in the eye-ball. The
+  black circle points out to us the true axis of the lens, which
+  is perpendicular to a plane passing through it. When the small
+  crystalline has been freed from all the adhering vitreous humour,
+  the capsule which contains it will have a surface as fine as a
+  pellicle of fluid. It is then to be dropped from the paper into a
+  cavity formed by a brass rim, and its position changed till the
+  black circle is parallel to the circular rim, in which case only
+  the axis of the lens will be a continuation of the axis of the
+  observer’s eye.--_Edin. Jour. Science_, vol. ii.
+
+
+LEUWENHOECK’S MICROSCOPES.
+
+Leuwenhoeck, the father of microscopical discovery, communicated to the
+Royal Society, in 1673, a description of the structure of a bee and a
+louse, seen by aid of his improved microscopes; and from this period
+until his decease in 1723, he regularly transmitted to the society his
+microscopical observations and discoveries, so that 375 of his papers
+and letters are preserved in the society’s archives, extending over
+fifty years. He further bequeathed to the Royal Society a cabinet of
+twenty-six microscopes, which he had ground himself and set in silver,
+mostly extracted by him from minerals; these microscopes were exhibited
+to Peter the Great when he was at Delft in 1698. In acknowledging
+the bequest, the council of the Royal Society, in 1724, presented
+Leuwenhoeck’s daughter with a handsome silver bowl, bearing the arms of
+the society.--_Weld’s History of the Royal Society_, vol. i.
+
+
+DIAMOND LENSES FOR MICROSCOPES.
+
+In recommending the employment of Diamond and other gems in the
+construction of Microscopes, Sir David Brewster has been met with
+the objection that they are too expensive for such a purpose; and,
+says Sir David, “they certainly are for instruments intended merely
+to instruct and amuse. But if we desire to make great discoveries,
+to unfold secrets yet hid in the cells of plants and animals, we
+must not grudge even a diamond to reveal them. If Mr. Cooper and Sir
+James South have given a couple of thousand pounds a piece for a
+refracting telescope, in order to study what have been miscalled ‘dots’
+and ‘lumps’ of light on the sky; and if Lord Rosse has expended far
+greater sums on a reflecting telescope for analysing what has been
+called ‘sparks of mud and vapour’ encumbering the azure purity of the
+heavens,--why should not other philosophers open their purse, if they
+have one, and other noblemen sacrifice some of their household jewels,
+to resolve the microscopic structures of our own real world, and
+disclose secrets which the Almighty must have intended that we should
+know?”--_Proceedings of the British Association_, 1857.
+
+
+THE EYE AND THE BRAIN SEEN THROUGH A MICROSCOPE.
+
+By a microscopic examination of the retina and optic nerve and
+the brain, M. Bauer found them to consist of globules of 1/2800th
+to 1/4000th an inch diameter, united by a transparent viscid and
+coagulable gelatinous fluid.
+
+
+MICROSCOPICAL EXAMINATION OF THE HAIR.
+
+If a hair be drawn between the finger and thumb, from the end to
+the root, it will be distinctly felt to give a greater resistance
+and a different sensation to that which is experienced when drawn
+the opposite way: in consequence, if the hair be rubbed between the
+fingers, it will only move one way (travelling in the direction of a
+line drawn from its termination to its origin from the head or body),
+so that each extremity may thus be easily distinguished, even in the
+dark, by the touch alone.
+
+The mystery is resolved by the achromatic microscope. A hair viewed on
+a dark ground as an _opaque_ object with a high power, not less than
+that of a lens of one-thirtieth of an inch focus, and dully illuminated
+by a _cup_, the hair is seen to be indented with teeth somewhat
+resembling those of a coarse round rasp, but extremely irregular and
+rugged: as these incline all in one direction, like those of a common
+file, viz. from the origin of the hair towards its extremity, it
+sufficiently explains the above singular property.
+
+This is a singular proof of the acuteness of the sense of feeling, for
+the said teeth may be felt much more easily than they can be seen. We
+may thus understand why a razor will cut a hair in two much more easily
+when drawn against its teeth than in the opposite direction.--_Dr.
+Goring._
+
+
+THE MICROSCOPE AND THE SEA.
+
+What myriads has the microscope revealed to us of the rich luxuriance
+of animal life in the ocean, and conveyed to our astonished senses
+a consciousness of the universality of life! In the oceanic depths
+every stratum of water is animated, and swarms with countless hosts of
+small luminiferous animalcules, mammaria, crustacea, peridinea, and
+circling nereides, which, when attracted to the surface by peculiar
+meteorological conditions, convert every wave into a foaming band of
+flashing light.
+
+
+USE OF THE MICROSCOPE TO MINERALOGISTS.
+
+M. Dufour has shown that an imponderable quantity of a substance
+can be crystallised; and that the crystals so obtained are quite
+characteristic of the substances, as of sugar, chloride of sodium,
+arsenic, and mercury. This process may be extremely valuable to the
+mineralogist and toxicologist when the substance for examination is too
+small to be submitted to tests. By aid of the microscope, also, shells
+are measured to the thousandth part of an inch.
+
+
+FINE DOWN OF QUARTZ.
+
+Sir David Brewster having broken in two a crystal of quartz of a smoky
+colour, found both surfaces of the fracture absolutely black; and the
+blackness appeared at first sight to be owing to a thin film of opaque
+matter which had insinuated itself into the crevice. This opinion,
+however, was untenable, as every part of the surface was black, and
+the two halves of the crystals could not have stuck together had the
+crevice extended across the whole section. Upon further examination Sir
+David found that the surface was perfectly transparent by transmitted
+light, and that the blackness of the surfaces arose from their being
+entirely composed of _a fine down of quartz_, or of short and slender
+filaments, whose diameter was so exceedingly small that they were
+incapable of reflecting a single ray of the strongest light; and they
+could not exceed the _one third of the millionth part of an inch_. This
+curious specimen is in the cabinet of her grace the Duchess of Gordon.
+
+
+MICROSCOPIC WRITING.
+
+Professor Kelland has shown, in Paris, on a spot no larger than
+the head of a small pin, by means of powerful microscopes, several
+specimens of distinct and beautiful writing, one of them containing
+the whole of the Lord’s Prayer written within this minute compass.
+In reference to this, two remarkable facts in Layard’s latest work
+on Nineveh show that the national records of Assyria were written on
+square bricks, in characters so small as scarcely to be legible without
+a microscope; in fact, a microscope, as we have just shown, was found
+in the ruins of Nimroud.
+
+
+HOW TO MAKE A MAGIC MIRROR.
+
+Draw a figure with weak gum-water upon the surface of a convex mirror.
+The thin film of gum thus deposited on the outline or details of the
+figure will not be visible in dispersed daylight; but when made to
+reflect the rays of the sun, or those of a divergent pencil, will
+be beautifully displayed by the lines and tints occasioned by the
+diffraction of light, or the interference of the rays passing through
+the film with those which pass by it.
+
+
+SIR DAVID BREWSTER’S KALEIDOSCOPE.
+
+The idea of this instrument, constructed for the purpose of creating
+and exhibiting a variety of beautiful and perfectly symmetrical forms,
+first occurred to Sir David Brewster in 1814, when he was engaged in
+experiments on the polarisation of light by successive reflections
+between plates of glass. The reflectors were in some instances inclined
+to each other; and he had occasion to remark the circular arrangement
+of the images of a candle round a centre, or the multiplication of the
+sectors formed by the extremities of the glass plates. In repeating
+at a subsequent period the experiments of M. Biot on the action of
+fluids upon light, Sir David Brewster placed the fluids in a trough,
+formed by two plates of glass cemented together at an angle; and the
+eye being necessarily placed at one end, some of the cement, which had
+been pressed through between the plates, appeared to be arranged into a
+regular figure. The remarkable symmetry which it presented led to Dr.
+Brewster’s investigation of the cause of this phenomenon; and in so
+doing he discovered the leading principles of the Kaleidoscope.
+
+By the advice of his friends, Dr. Brewster took out a patent for his
+invention; in the specification of which he describes the kaleidoscope
+in two different forms. The instrument, however, having been shown
+to several opticians in London, became known before he could avail
+himself of his patent; and being simple in principle, it was at once
+largely manufactured. It is calculated that not less than 200,000
+kaleidoscopes were sold in three months in London and Paris; though out
+of this number, Dr. Brewster says, not perhaps 1000 were constructed
+upon scientific principles, or were capable of giving any thing like a
+correct idea of the power of his kaleidoscope.
+
+
+THE KALEIDOSCOPE THOUGHT TO BE ANTICIPATED.
+
+In the seventh edition of a work on gardening and planting, published
+in 1739, by Richard Bradley, F.R.S., late Professor of Botany in the
+University of Cambridge, we find the following details of an invention,
+“by which the best designers and draughtsmen may improve and help
+their fancies. They must choose two pieces of looking-glass of equal
+bigness, of the figure of a long square. These must be covered on
+the back with paper or silk, to prevent rubbing off the silver. This
+covering must be so put on that nothing of it appears about the edges
+of the bright side. The glasses being thus prepared, must be laid face
+to face, and hinged together so that they may be made to open and shut
+at pleasure like the leaves of a book.” After showing how various
+figures are to be looked at in these glasses under the same opening,
+and how the same figure may be varied under the different openings, the
+ingenious artist thus concludes: “If it should happen that the reader
+has any number of plans for parterres or wildernesses by him, he may by
+this method alter them at his pleasure, and produce such innumerable
+varieties as it is not possible the most able designer could ever have
+contrived.”
+
+
+MAGIC OF PHOTOGRAPHY.
+
+Professor Moser of Königsberg has discovered that all bodies, even
+in the dark, throw out invisible rays; and that these bodies, when
+placed at a small distance from polished surfaces of all kinds, depict
+themselves upon such surfaces in forms which remain invisible till
+they are developed by the human breath or by the vapours of mercury or
+iodine. Even if the sun’s image is made to pass over a plate of glass,
+the light tread of its rays will leave behind it an invisible track,
+which the human breath will instantly reveal.
+
+  Among the early attempts to take pictures by the rays of the sun
+  was a very interesting and successful experiment made by Dr. Thomas
+  Young. In 1802, when Mr. Wedgewood was “making profiles by the
+  agency of light,” and Sir Humphry Davy was “copying on prepared
+  paper the images of small objects produced by means of the solar
+  microscope,” Dr. Young was taking photographs upon paper dipped in
+  a solution of nitrate of silver, of the coloured rings observed
+  by Newton; and his experiments clearly proved that the agent was
+  not the luminous rays in the sun’s light, but the invisible or
+  chemical rays beyond the violet. This experiment is described in
+  the Bakerian Lecture, 1803.
+
+  Niepce (says Mr. Hunt) pursued a physical investigation of the
+  curious change, and found that all bodies were influenced by this
+  principle radiated from the sun. Daguerre[14] produced effects from
+  the solar pencil which no artist could approach; and Talbot and
+  others extended the application. Herschel took up the inquiry; and
+  he, with his usual power of inductive search and of philosophical
+  deduction, presented the world with a class of discoveries which
+  showed how vast a field of investigation was opening for the
+  younger races of mankind.
+
+  The first attempts in photography, which were made at the
+  instigation of M. Arago, by order of the French Government, to
+  copy the Egyptian tombs and temples and the remains of the Aztecs
+  in Central America, were failures. Although the photographers
+  employed succeeded to admiration, in Paris, in producing pictures
+  in a few minutes, they found often that an exposure of an hour
+  was insufficient under the bright and glowing illumination of a
+  southern sky.
+
+
+THE BEST SKY FOR PHOTOGRAPHY.
+
+Contrary to all preconceived ideas, experience proves that the brighter
+the sky that shines above the camera the more tardy the action within
+it. Italy and Malta do their work slower than Paris. Under the
+brilliant light of a Mexican sun, half an hour is required to produce
+effects which in England would occupy but a minute. In the burning
+atmosphere of India, though photographical the year round, the process
+is comparatively slow and difficult to manage; while in the clear,
+beautiful, and moreover cool, light of the higher Alps of Europe, it
+has been proved that the production of a picture requires many more
+minutes, even with the most sensitive preparations, than in the murky
+atmosphere of London. Upon the whole, the temperate skies of this
+country may be pronounced favourable to photographic action; a fact
+for which the prevailing characteristic of our climate may partially
+account, humidity being an indispensable condition for the working
+state both of paper and chemicals.--_Quarterly Review_, No. 202.
+
+
+PHOTOGRAPHIC EFFECTS OF LIGHTNING.
+
+The following authenticated instances of this singular phenomenon have
+been communicated to the Royal Society by Andrés Poey, Director of the
+Observatory at Havana:
+
+  Benjamin Franklin, in 1786, stated that about twenty years
+  previous, a man who was standing opposite a tree that had just been
+  struck by “a thunderbolt” had on his breast an exact representation
+  of that tree.
+
+  In the New-York _Journal of Commerce_, August 26th, 1853, it is
+  related that “a little girl was standing at a window, before which
+  was a young maple-tree; after a brilliant flash of lightning, a
+  complete image of the tree was found imprinted on her body.”
+
+  M. Raspail relates that, in 1855, a boy having climbed a tree for
+  the purpose of robbing a bird’s nest, the tree was struck, and
+  the boy thrown upon the ground; on his breast the image of the
+  tree, with the bird and nest on one of its branches, appeared very
+  plainly.
+
+  M. Olioli, a learned Italian, brought before the Scientific
+  Congress at Naples the following four instances: 1. In September
+  1825, the foremast of a brigantine in the Bay of St. Arniro
+  was struck by lightning, when a sailor sitting under the mast
+  was struck dead, and on his back was found an impression of a
+  horse-shoe, similar even in size to that fixed on the mast-head. 2.
+  A sailor, standing in a similar position, was struck by lightning,
+  and had on his left breast the impression of the number 4 4, with a
+  dot between the two figures, just as they appeared at the extremity
+  of one of the masts. 3. On the 9th October 1836, a young man was
+  found struck by lightning; he had on a girdle, with some gold
+  coins in it, which were imprinted on his skin in the order they
+  were placed in the girdle,--a series of circles, with one point of
+  contact, being plainly visible. 4. In 1847, Mme. Morosa, an Italian
+  lady of Lugano, was sitting near a window during a thunderstorm,
+  and perceived the commotion, but felt no injury; but a flower which
+  happened to be in the path of the electric current was perfectly
+  reproduced on one of her legs, and there remained permanently.
+
+  M. Poey himself witnessed the following instance in Cuba. On July
+  24th, 1852, a poplar-tree in a coffee-plantation was struck by
+  lightning, and on one of the large dry leaves was found an exact
+  representation of some pine-trees that lay 367 yards distant.
+
+M. Poey considers these lightning impressions to have been produced
+in the same manner as the electric images obtained by Moser, Riess,
+Karster, Grove, Fox Talbot, and others, either by statical or dynamical
+electricity of different intensities. The fact that impressions are
+made through the garments is easily accounted for by their rough
+texture not preventing the lightning passing through them with the
+impression. To corroborate this view, M. Poey mentions an instance of
+lightning passing down a chimney into a trunk, in which was found an
+inch depth of soot, which must have passed through the wood itself.
+
+
+PHOTOGRAPHIC SURVEYING.
+
+During the summer of 1854, in the Baltic, the British steamers employed
+in examining the enemy’s coasts and fortifications took photographic
+views for reference and minute examination. With the steamer moving
+at the rate of fifteen knots an hour, the most perfect definitions of
+coasts and batteries were obtained. Outlines of the coasts, correct in
+height and distance, have been faithfully transcribed; and all details
+of the fortresses passed under this photographic review are accurately
+recorded.
+
+  It is curious to reflect that the aids to photographic development
+  all date within the last half-century, and are but little older
+  than photography itself. It was not until 1811 that the chemical
+  substance called iodine, on which the foundations of all popular
+  photography rest, was discovered at all; bromine, the only other
+  substance equally sensitive, not till 1826. The invention of the
+  electro process was about simultaneous with that of photography
+  itself. Gutta-percha only just preceded the substance of which
+  collodion is made; the ether and chloroform, which are used in
+  some methods, that of collodion. We say nothing of the optical
+  improvements previously contrived or adapted for the purpose of the
+  photograph: the achromatic lenses, which correct the discrepancy
+  between the visual and chemical foci; the double lenses, which
+  increase the force of the action; the binocular lenses, which
+  do the work of the stereoscope; nor of the innumerable other
+  mechanical aids which have sprung up for its use.
+
+
+THE STEREOSCOPE AND THE PHOTOGRAPH.
+
+When once the availability of one great primitive agent is worked out,
+it is easy to foresee how extensively it will assist in unravelling
+other secrets in natural science. The simple principle of the
+Stereoscope, for instance, might have been discovered a century ago,
+for the reasoning which led to it was independent of all the properties
+of light; but it could never have been illustrated, far less multiplied
+as it now is, without Photography. A few diagrams, of sufficient
+identity and difference to prove the truth of the principle, might
+have been constructed by hand, for the gratification of a few sages;
+but no artist, it is to be hoped, could have been found possessing
+the requisite ability and stupidity to execute the two portraits, or
+two groups, or two interiors, or two landscapes, identical in every
+minutia of the most elaborate detail, and yet differing in point of
+view by the inch between the two human eyes, by which the principle is
+brought to the level of any capacity. Here, therefore, the accuracy and
+insensibility of a machine could alone avail; and if in the order of
+things the cheap popular toy which the stereoscope now represents was
+necessary for the use of man, the photograph was first necessary for
+the service of the stereoscope.--_Quarterly Review_, No. 202.
+
+
+THE STEREOSCOPE SIMPLIFIED.
+
+When we look at any round object, first with one eye, and then with
+the other, we discover that with the right eye we see most of the
+right-hand side of the object, and with the left eye most of the
+left-hand side. These two images are combined, and we see an object
+which we know to be round.
+
+This is illustrated by the _Stereoscope_, which consists of two mirrors
+placed each at an angle of 45 deg., or of two semi-lenses turned with
+their curved sides towards each other. To view its phenomena two
+pictures are obtained by the camera on photographic paper of any object
+in two positions, corresponding with the conditions of viewing it with
+the two eyes. By the mirrors on the lenses these dissimilar pictures
+are combined within the eye, and the vision of an actually solid object
+is produced from the pictures represented on a plane surface. Hence the
+name of the instrument, which signifies _Solid I see_.--_Hunt’s Poetry
+of Science._
+
+
+PHOTO-GALVANIC ENGRAVING.
+
+That which was the chief aid of Niepce in the humblest dawn of the
+art, viz. to transform the photographic plate into a surface capable
+of being printed, is in the above process done by the coöperation of
+Electricity with Photography. This invention of M. Pretsch, of Vienna,
+differs from all other attempts for the same purpose in not operating
+upon the photographic tablet itself, and by discarding the usual means
+of varnishes and bitings-in. The process is simply this: A glass tablet
+is coated with gelatine diluted till it forms a jelly, and containing
+bi-chromate of potash, nitrate of silver, and iodide of potassium. Upon
+this, when dry, is placed face downwards a paper positive, through
+which the light, being allowed to fall, leaves upon the gelatine a
+representation of the print. It is then soaked in water; and while
+the parts acted upon by the light are comparatively unaffected by the
+fluid, the remainder of the jelly swells, and rising above the general
+surface, gives a picture in relief, resembling an ordinary engraving
+upon wood. Of this intaglio a cast is now taken in gutta-percha, to
+which the electro process in copper being applied, a plate or matrix is
+produced, bearing on it an exact repetition of the original positive
+picture. All that now remains to be done is to repeat the electro
+process; and the result is a copper-plate in the necessary relievo, of
+which it has been said nature furnished the materials and science the
+artist, the inferior workman being only needed to roll it through the
+press.--_Quarterly Review_, No. 202.
+
+
+SCIENCE OF THE SOAP-BUBBLE.
+
+Few of the minor ingenuities of mankind have amused so many individuals
+as the blowing of bubbles with soap-lather from the bowl of a
+tobacco-pipe; yet how few who in childhood’s careless hours have thus
+amused themselves, have in after-life become acquainted with the
+beautiful phenomena of light which the soap-bubble will enable us to
+illustrate!
+
+Usually the bubble is formed within the bowl of a tobacco-pipe, and
+so inflated by blowing through the stem. It is also produced by
+introducing a capillary tube under the surface of soapy water, and so
+raising a bubble, which may be inflated to any convenient size. It is
+then guarded with a glass cover, to prevent its bursting by currents of
+air, evaporation, and other causes.
+
+When the bubble is first blown, its form is elliptical, into which it
+is drawn by its gravity being resisted; but the instant it is detached
+from the pipe, and allowed to float in air, it becomes a perfect
+sphere, since the air within presses equally in all directions. There
+is also a strong cohesive attraction in the particles of soap and
+water, after having been forcibly distended; and as a sphere or globe
+possesses less surface than any other figure of equal capacity, it is
+of all forms the best adapted to the closest approximation of the
+particles of soap and water, which is another reason why the bubble
+is globular. The film of which the bubble consists is inconceivably
+thin (not exceeding the two-millionth part of an inch); and by the
+evaporation from its surface, the contraction and expansion of the air
+within, and the tendency of the soap-lather to gravitate towards the
+lower part of the bubble, and consequently to render the upper part
+still thinner, it follows that the bubble lasts but a few seconds. If,
+however, it were blown in a glass vessel, and the latter immediately
+closed, it might remain for some time; Dr. Paris thus preserved a
+bubble for a considerable period.
+
+Dr. Hooke, by means of the coloured rings upon the soap-bubble, studied
+the curious subject of the colours of thin plates, and its application
+to explain the colours of natural bodies. Various phenomena were also
+discovered by Newton, who thus did not disdain to make a soap-bubble
+the object of his study. The colours which are reflected from the upper
+surface of the bubble are caused by the decomposition of the light
+which falls upon it; and the range of the phenomena is alike extensive
+and beautiful.[15]
+
+Newton (says Sir D. Brewster), having covered the soap-bubble with a
+glass shade, saw its colours emerge in regular order, like so many
+concentric rings encompassing the top of it. As the bubble grew thinner
+by the continual subsidence of the water, the rings dilated slowly,
+and overspread the whole of it, descending to the bottom, where they
+vanished successively. When the colours had all emerged from the top,
+there arose in the centre of the rings a small round black spot,
+dilating it to more than half an inch in breadth till the bubble
+burst. Upon examining the rings between the object-glasses, Newton
+found that when they were only _eight_ or _nine_ in number, more than
+_forty_ could be seen by viewing them through a prism; and even when
+the plate of air seemed all over uniformly white, multitudes of rings
+were disclosed by the prism. By means of these observations Newton was
+enabled to form his _Scale of Colours_, of great value in all optical
+researches.
+
+Dr. Reade has thus produced a permanent soap-bubble:
+
+  Put into a six-ounce phial two ounces of distilled water, and set
+  the phial in a vessel of water boiling on the fire. The water in
+  the phial will soon boil, and steam will issue from its mouth,
+  expelling the whole of the atmospheric air from within. Then throw
+  in a piece of soap about the size of a small pea, cork the phial,
+  and at the same instant remove it and the vessel from the fire.
+  Then press the cork farther into the neck of the phial, and cover
+  it thickly with sealing-wax; and when the contents are cold, a
+  perfect vacuum will be formed within the bottle,--much better,
+  indeed, than can be produced by the best-constructed air-pump.
+
+  To form a bubble, hold the bottle horizontally in both hands, and
+  give it a sudden upward motion, which will throw the liquid into a
+  wave, whose crest touching the upper interior surface of the phial,
+  the tenacity of the liquid will cause a film to be retained all
+  round the phial. Next place the phial on its bottom; when the film
+  will form a section of the cylinder, being nearly but never quite
+  horizontal. The film will be now colourless, since it reflects all
+  the light which falls upon it. By remaining at rest for a minute or
+  two, minute currents of lather will descend by their gravitating
+  force down the inclined plane formed by the film, the upper part of
+  which thus becomes drained to the necessary thinness; and this is
+  the part to be observed.
+
+Several concentric segments of coloured rings are produced; the
+colours, beginning from the top, being as follows:
+
+    _1st order_: Black, white, yellow, orange, red.
+    _2d order_: Purple, blue, white, yellow, red.
+    _3d order_: Purple, blue, green, yellowish-green, white, red.
+    _4th order_: Purple, blue, green, white, red.
+    _5th order_: Greenish-blue, very pale red.
+    _6th order_: Greenish-blue, pink.
+    _7th order_: Greenish-blue, pink.
+
+As the segments advance they get broader, while the film becomes
+thinner and thinner. The several orders disappear upwards as the film
+becomes too thin to reflect their colours, until the first order alone
+remains, occupying the whole surface of the film. Of this order the
+red disappears first, then the orange, and lastly the yellow. The film
+is now divided by a line into two nearly equal portions, one black and
+the other white. This remains for some time; at length the film becomes
+too thin to hold together, and then vanishes. The colours are not faint
+and imperfect, but well defined, glowing with gorgeous hues, or melting
+into tints so exquisite as to have no rival through the whole circle
+of the arts. We quote these details from Mr. Tomlinson’s excellent
+_Student’s Manual of Natural Philosophy_.
+
+  We find the following anecdote related of Newton at the above
+  period. When Sir Isaac changed his residence, and went to live in
+  St. Martin’s Street, Leicester Square, his next-door neighbour was
+  a widow lady, who was much puzzled by the little she observed of
+  the habits of the philosopher. A Fellow of the Royal Society called
+  upon her one day, when, among her domestic news, she mentioned that
+  some one had come to reside in the adjoining house who, she felt
+  certain, was a poor crazy gentleman, “because,” she continued,
+  “he diverts himself in the oddest way imaginable. Every morning,
+  when the sun shines so brightly that we are obliged to draw the
+  window-blinds, he takes his seat on a little stool before a tub
+  of soapsuds, and occupies himself for hours blowing soap-bubbles
+  through a common clay-pipe, which bubbles he intently watches
+  floating about till they burst. He is doubtless,” she added, “now
+  at his favourite amusement, for it is a fine day; do come and look
+  at him.” The gentleman smiled, and they went upstairs; when, after
+  looking through the staircase-window into the adjoining court-yard,
+  he turned and said: “My dear madam, the person whom you suppose
+  to be a poor lunatic is no other than the great Sir Isaac Newton
+  studying the refraction of light upon thin plates; a phenomenon
+  which is beautifully exhibited on the surface of a common
+  soap-bubble.”
+
+
+LIGHT FROM QUARTZ.
+
+Among natural phenomena (says Sir David Brewster) illustrative of the
+colours of thin plates, we find none more remarkable than one exhibited
+by the fracture of a large crystal of quartz of a smoky colour, and
+about two and a quarter inches in diameter. The surface of fracture,
+in place of being a face or cleavage, or irregularly conchoidal, as we
+have sometimes seen it, was filamentous, like a surface of velvet, and
+consisted of short fibres, so small as to be incapable of reflecting
+light. Their size could not have been greater than the third of the
+millionth part of an inch, or one-fourth of the thinnest part of the
+soap-bubble when it exhibits the black spot where it bursts.
+
+
+CAN THE CAT SEE IN THE DARK?
+
+No, in all probability, says the reader; but the opposite popular
+belief is supported by eminent naturalists.
+
+  Buffon says: “The eyes of the cat shine in the dark somewhat like
+  diamonds, which throw out during the night the light with which
+  they were in a manner impregnated during the day.”
+
+  Valmont de Bamare says: “The pupil of the cat is during the night
+  still deeply imbued with the light of the day;” and again, “the
+  eyes of the cat are during the night so imbued with light that they
+  then appear very shining and luminous.”
+
+  Spallanzani says: “The eyes of cats, polecats, and several other
+  animals, shine in the dark like two small tapers;” and he adds that
+  this light is phosphoric.
+
+  Treviranus says: “The eyes of the cat _shine where no rays of
+  light penetrate_; and the light must in many, if not in all, cases
+  proceed from the eye itself.”
+
+Now, that the eyes of the cat do shine in the dark is to a certain
+extent true: but we have to inquire whether by _dark_ is meant the
+entire absence of light; and it will be found that the solution of this
+question will dispose of several assertions and theories which have for
+centuries perplexed the subject.
+
+Dr. Karl Ludwig Esser has published in Karsten’s Archives the results
+of an experimental inquiry on the luminous appearance of the eyes of
+the cat and other animals, carefully distinguishing such as evolve
+light from those which only reflect it. Having brought a cat into a
+half-darkened room, he observed from a certain direction that the cat’s
+eyes, when _opposite the window_, sparkled brilliantly; but in other
+positions the light suddenly vanished. On causing the cat to be held
+so as to exhibit the light, and then gradually darkening the room, the
+light disappeared by the time the room was made quite dark.
+
+In another experiment, a cat was placed opposite the window in a
+darkened room. A few rays were permitted to enter, and by adjusting the
+light, one or both of the cat’s eyes were made to shine. In proportion
+as the pupil was dilated, the eyes were brilliant. By suddenly
+admitting a strong glare of light into the room, the pupil contracted;
+and then suddenly darkening the room, the eye exhibited a small round
+luminous point, which enlarged as the pupil dilated.
+
+The eyes of the cat sparkle most when the animal is in a lurking
+position, or in a state of irritation. Indeed, the eyes of all animals,
+as well as of man, appear brighter when in rage than in a quiescent
+state, which Collins has commemorated in his Ode on the Passions:
+
+    “Next Anger rushed, his eyes on fire.”
+
+This brilliancy is said to arise from an increased secretion of the
+lachrymal fluid on the surface of the eye, by which the reflection of
+the light is increased. Dr. Esser, in places absolutely dark, never
+discovered the slightest trace of light in the eye of the cat; and he
+has no doubt that in all cases where cats’ eyes have been seen to shine
+in dark places, such as a cellar, light penetrated through some window
+or aperture, and fell upon the eyes of the animal as it turned towards
+the opening, while the observer was favourably situated to obtain a
+view of the reflection.
+
+To prove more clearly that this light does not depend upon the will of
+the animal, nor upon its angry passions, experiments were made upon
+the head of a dead cat. The sun’s rays were admitted through a small
+aperture; and falling immediately upon the eyes, caused them to glow
+with a beautiful green light more vivid even than in the case of a
+living animal, on account of the increased dilatation of the pupil.
+It was also remarked that black and fox-coloured cats gave a brighter
+light than gray and white cats.
+
+To ascertain the cause of this luminous appearance Dr. Esser dissected
+the eyes of cats, and exposed them to a small regulated amount of light
+after having removed different portions. The light was not diminished
+by the removal of the cornea, but only changed in colour. The light
+still continued after the iris was displaced; but on taking away the
+crystalline lens it greatly diminished both in intensity and colour.
+Dr. Esser then conjectured that the tapetum in the hinder part of the
+eye must form a spot which caused the reflection of the incident
+rays of light, and thus produce the shining; and this appeared more
+probable as the light of the eye now seemed to emanate from a single
+spot. Having taken away the vitreous humour, Dr. Esser observed that
+the entire want of the pigment in the hinder part of the choroid coat,
+where the optic nerve enters, formed a greenish, silver-coloured,
+changeable oblong spot, which was not symmetrical, but surrounded the
+optic nerve so that the greater part was above and only the smaller
+part below it; wherefore the greater part lay beyond the axis of
+vision. It is this spot, therefore, that produces the reflection of the
+incident rays of light, and beyond all doubt, according to its tint,
+contributes to the different colouring of the light.
+
+It may be as well to explain that the interior of the eye is coated
+with a black pigment, which has the same effect as the black colour
+given to the inner surface of optical instruments: it absorbs any
+rays of light that may be reflected within the eye, and prevents
+them from being thrown again upon the retina so as to interfere with
+the distinctness of the images formed upon it. The retina is very
+transparent; and if the surface behind it, instead of being of a dark
+colour, were capable of reflecting light, the luminous rays which had
+already acted on the retina would be reflected back again through it,
+and not only dazzle from excess of light, but also confuse and render
+indistinct the images formed on the retina. Now in the case of the cat
+this black pigment, or a portion of it, is wanting; and those parts of
+the eye from which it is absent, having either a white or a metallic
+lustre, are called the tapetum. The smallest portion of light entering
+from it is reflected as by a concave mirror; and hence it is that the
+eyes of animals provided with this structure are luminous in a very
+faint light.
+
+These experiments and observations show that the shining of the eyes
+of the cat does not arise from a phosphoric light, but only from a
+reflected light; that consequently it is not an effect of the will of
+the animal, or of violent passions; that their shining does not appear
+in absolute darkness; and that it cannot enable the animal to move
+securely in the dark.
+
+It has been proved by experiment that there exists a set of rays of
+light of far higher refrangibility than those seen in the ordinary
+Newtonian spectrum. Mr. Hunt considers it probable that these highly
+refrangible rays, although under ordinary circumstances invisible
+to the human eye, may be adapted to produce the necessary degree
+of excitement upon which vision depends in the optic nerves of the
+night-roaming animals. The bat, the owl, and the cat may see in the
+gloom of the night by the aid of rays which are invisible to, or
+inactive on, the eyes of man or those animals which require the light
+of day for perfect vision.
+
+
+
+
+Astronomy.
+
+
+THE GREAT TRUTHS OF ASTRONOMY.
+
+The difficulty of understanding these marvellous truths has been
+glanced at by an old divine (see _Things not generally Known_, p.
+1); but the rarity of their full comprehension by those unskilled in
+mathematical science is more powerfully urged by Lord Brougham in these
+cogent terms:
+
+  Satisfying himself of the laws which regulate the mutual actions
+  of the planetary bodies, the mathematician can convince himself of
+  a truth yet more sublime than Newton’s discovery of gravitation,
+  though flowing from it; and must yield his assent to the marvellous
+  position, that all the irregularities occasioned in the system
+  of the universe by the mutual attraction of its members are
+  periodical, and subject to an eternal law, which prevents them from
+  ever exceeding a stated amount, and secures through all time the
+  balanced structure of a universe composed of bodies whose mighty
+  bulk and prodigious swiftness of motion mock the utmost efforts
+  of the human imagination. All these truths are to the skilful
+  mathematician as thoroughly known, and their evidence is as clear,
+  as the simplest proposition of arithmetic to common understandings.
+  But how few are those who thus know and comprehend them! Of all
+  the millions that thoroughly believe these truths, certainly not a
+  thousand individuals are capable of following even any considerable
+  portion of the demonstrations upon which they rest; and probably
+  not a hundred now living have ever gone through the whole steps
+  of these demonstrations.--_Dissertations on Subjects of Science
+  connected with Natural Theology_, vol. ii.
+
+Sir David Brewster thus impressively illustrates the same subject:
+
+  Minds fitted and prepared for this species of inquiry are
+  capable of appreciating the great variety of evidence by
+  which the truths of the planetary system are established; but
+  thousands of individuals, and many who are highly distinguished
+  in other branches of knowledge, are incapable of understanding
+  such researches, and view with a sceptical eye the great and
+  irrefragable truths of astronomy.
+
+  That the sun is stationary in the centre of our system; that
+  the earth moves round the sun, and round its own axis; that
+  the diameter of the earth is 8000 miles, and that of the sun
+  _one hundred and ten times as great_; that the earth’s orbit is
+  190,000,000 of miles in breadth; and that if this immense space
+  were filled with light, it would appear only like a luminous point
+  at the nearest fixed star,--are positions absolutely unintelligible
+  and incredible to all who have not carefully studied the subject.
+  To millions of our species, then, the great Book of Nature is
+  absolutely sealed; though it is in the power of all to unfold its
+  pages, and to peruse those glowing passages which proclaim the
+  power and wisdom of its Author.
+
+
+ASTRONOMY AND DATES ON MONUMENTS.
+
+Astronomy is a useful aid in discovering the Dates of ancient
+Monuments. Thus, on the ceiling of a portico among the ruins of
+Tentyris are the twelve signs of the Zodiac, placed according to the
+apparent motion of the sun. According to this Zodiac, the summer
+solstice is in Leo; from which it is easy to compute, by the precession
+of the equinoxes of 50″·1 annually, that the Zodiac of Tentyris must
+have been made 4000 years ago.
+
+Mrs. Somerville relates that she once witnessed the ascertainment of
+the date of a Papyrus by means of astronomy. The manuscript was found
+in Egypt, in a mummy-case; and its antiquity was determined by the
+configuration of the heavens at the time of its construction. It proved
+to be a horoscope of the time of Ptolemy.
+
+
+“THE CRYSTAL VAULT OF HEAVEN.”
+
+This poetic designation dates back as far as the early period of
+Anaximenes; but the first clearly defined signification of the idea on
+which the term is based occurs in Empedocles. This philosopher regarded
+the heaven of the fixed stars as a solid mass, formed from the ether
+which had been rendered crystalline by the action of fire.
+
+In the Middle Ages, the fathers of the Church believed the firmament to
+consist of from seven to ten glassy strata, incasing each other like
+the different coatings of an onion. This supposition still keeps its
+ground in some of the monasteries of southern Europe, where Humboldt
+was greatly surprised to hear a venerable prelate express an opinion in
+reference to the fall of aerolites at Aigle, that the bodies we called
+meteoric stones with vitrified crusts were not portions of the fallen
+stone itself, but simply fragments of the crystal vault shattered by it
+in its fall.
+
+Empedocles maintained that the fixed stars were riveted to the
+crystal heavens; but that the planets were free and unconstrained.
+It is difficult to conceive how, according to Plato in the _Timæus_,
+the fixed stars, riveted as they are to solid spheres, could rotate
+independently.
+
+Among the ancient views, it may be mentioned that the equal distance
+at which the stars remained, while the whole vault of heaven seemed to
+move from east to west, had led to the idea of a firmament and a solid
+crystal sphere, in which Anaximenes (who was probably not much later
+than Pythagoras) had conjectured that the stars were riveted like nails.
+
+
+MUSIC OF THE SPHERES.
+
+The Pythagoreans, in applying their theory of numbers to the
+geometrical consideration of the five regular bodies, to the musical
+intervals of tone which determine a word and form different kinds
+of sounds, extended it even to the system of the universe itself;
+supposing that the moving, and, as it were, vibrating planets, exciting
+sound-waves, must produce a _spheral music_, according to the harmonic
+relations of their intervals of space. “This music,” they add, “would
+be perceived by the human ear, if it was not rendered insensible by
+extreme familiarity, as it is perpetual, and men are accustomed to it
+from childhood.”
+
+  The Pythagoreans affirm, in order to justify the reality of the
+  tones produced by the revolution of the spheres, that hearing takes
+  place only where there is an alternation of sound and silence. The
+  inaudibility of the spheral music is also accounted for by its
+  overpowering the senses. Aristotle himself calls the Pythagorean
+  tone-myth pleasing and ingenious, but untrue.
+
+Plato attempted to illustrate the tones of the universe in an
+agreeable picture, by attributing to each of the planetary spheres a
+syren, who, supported by the stern daughters of Necessity, the three
+Fates, maintain the eternal revolution of the world’s axis. Mention
+is constantly made of the harmony of the spheres, though generally
+reproachfully, throughout the writings of Christian antiquity and the
+Middle Ages, from Basil the Great to Thomas Aquinas and Petrus Alliacus.
+
+At the close of the sixteenth century, Kepler revived these musical
+ideas, and sought to trace out the analogies between the relations of
+tone and the distances of the planets; and Tycho Brahe was of opinion
+that the revolving conical bodies were capable of vibrating the
+celestial air (what we now call “resisting medium”) so as to produce
+tones. Yet Kepler, although he had talked of Venus and the Earth
+sounding sharp in aphelion and flat in perihelion, and the highest tone
+of Jupiter and that of Venus coinciding in flat accord, positively
+declared there to be “no such things as sounds among the heavenly
+bodies, nor is their motion so turbulent as to elicit noise from the
+attrition of the celestial air.” (See _Things not generally Known_, p.
+44.)
+
+
+“MORE WORLDS THAN ONE.”
+
+Although this opinion was maintained incidentally by various writers
+both on astronomy[16] and natural religion, yet M. Fontenelle was the
+first individual who wrote a treatise on the _Plurality of Worlds_,
+which appeared in 1685, the year before the publication of Newton’s
+_Principia_. Fontenelle’s work consists of five chapters: 1. The earth
+is a planet which turns round its axis, and also round the sun. 2. The
+moon is a habitable world. 3. Particulars concerning the world in the
+moon, and that the other planets are also inhabited. 4. Particulars of
+the worlds of Venus, Mercury, Mars, Jupiter, and Saturn. 5. The fixed
+stars are as many suns, each of which illuminates a world. In a future
+edition, 1719, Fontenelle added, 6. New thoughts which confirm those in
+the preceding conversations, and the latest discoveries which have been
+made in the heavens. The next work on the subject was the _Theory of
+the Universe, or Conjectures concerning the Celestial Bodies and their
+Inhabitants_, 1698, by Christian Huygens, the contemporary of Newton.
+
+The doctrine is maintained by almost all the distinguished astronomers
+and writers who have flourished since the true figure of the earth was
+determined. Giordano Bruna of Nola, Kepler, and Tycho Brahe, believed
+in it; and Cardinal Cusa and Bruno, before the discovery of binary
+systems among the stars, believed also that the stars were inhabited.
+Sir Isaac Newton likewise adopted the belief; and Dr. Bentley, Master
+of Trinity College, Cambridge, in his eighth sermon on the Confutation
+of Atheism from the origin and frame of the world, has ably maintained
+the same doctrine. In our own day we may number among its supporters
+the distinguished names of the Marquis de la Place, Sir William and
+Sir John Herschel, Dr. Chalmers, Isaac Taylor, and M. Arago. Dr.
+Chalmers maintains the doctrine in his _Astronomical Discourses_, which
+one Alexander Maxwell (who did not believe in the grand truths of
+astronomy) attempted to controvert, in 1820, in a chapter of a volume
+entitled _Plurality of Worlds_.
+
+Next appeared _Of a Plurality of Worlds_, attributed to the Rev. Dr.
+Whewell, Master of Trinity College, Cambridge; urging the theological
+not less than the scientific reasons for believing in the old tradition
+of a single world, and maintaining that “the earth is really the
+largest planetary body in the solar system,--its domestic hearth,
+and the only world in the universe.” “I do not pretend,” says Dr.
+Whewell, “to disprove the plurality of worlds; but I ask in vain for
+any argument which makes the doctrine probable.” “It is too remote
+from knowledge to be either proved or disproved.” Sir David Brewster
+has replied to Dr. Whewell’s Essay, in _More Worlds than One, the
+Creed of the Philosopher and the Hope of the Christian_, emphatically
+maintaining that analogy strongly countenances the idea of all the
+solar planets, if not all worlds in the universe, being peopled with
+creatures not dissimilar in being and nature to the inhabitants
+of the earth. This view is supported in _Scientific Certainties of
+Planetary Life_, by T. C. Simon, who well treats one point of the
+argument--that mere distance of the planets from the central sun
+does not determine the condition as to light and heat, but that the
+density of the ethereal medium enters largely into the calculation. Mr.
+Simon’s general conclusion is, that “neither on account of deficient
+or excessive heat, nor with regard to the density of the materials,
+nor with regard to the force of gravity on the surface, is there the
+slightest pretext for supposing that all the planets of our system
+are not inhabited by intellectual creatures with animal bodies like
+ourselves,--moral beings, who know and love their great Maker, and
+who wait, like the rest of His creation, upon His providence and upon
+His care.” One of the leading points of Dr. Whewell’s Essay is, that
+we should not elevate the conjectures of analogy into the rank of
+scientific certainties; and that “the force of all the presumptions
+drawn from physical reasoning for the opinion of planets and stars
+being either inhabited or uninhabited is so small, that the belief of
+all thoughtful persons on this subject will be determined by moral,
+metaphysical, and theological considerations.”
+
+
+WORLDS TO COME--ABODES OF THE BLEST.
+
+Sir David Brewster, in his eloquent advocacy of the doctrine of “more
+worlds than one,” thus argues for their peopling:
+
+  Man, in his future state of existence, is to consist, as at
+  present, of a spiritual nature residing in a corporeal frame. He
+  must live, therefore, upon a material planet, subject to all the
+  laws of matter, and performing functions for which a material body
+  is indispensable. We must consequently find for the race of Adam,
+  if not races that may have preceded him, a material home upon which
+  they may reside, or by which they may travel, by means unknown to
+  us, to other localities in the universe. At the present hour, the
+  inhabitants of the earth are nearly _a thousand millions_; and
+  by whatever process we may compute the numbers that have existed
+  before the present generation, and estimate those that are yet to
+  inherit the earth, we shall obtain a population which the habitable
+  parts of our globe could not possibly accommodate. If there is not
+  room, then, on our earth for the millions of millions of beings who
+  have lived and died upon its surface, and who may yet live and die
+  during the period fixed for its occupation by man, we can scarcely
+  doubt that their future abode must be on some of the primary or
+  secondary planets of the solar system, whose inhabitants have
+  ceased to exist like those on the earth, or upon planets in our own
+  or in other systems which have been in a state of preparation, as
+  our earth was, for the advent of intellectual life.
+
+
+“GAUGING THE HEAVENS.”
+
+Sir William Herschel, in 1785, conceived the happy idea of counting
+the number of stars which passed at different heights and in various
+directions over the field of view, of fifteen minutes in diameter,
+of his twenty-feet reflecting telescope. The field of view each time
+embraced only 1/833000th of the whole heavens; and it would therefore
+require, according to Struve, eighty-three years to gauge the whole
+sphere by a similar process.
+
+
+VELOCITY OF THE SOLAR SYSTEM.
+
+M. F. W. G. Struve gives as the splendid result of the united studies
+of MM. Argelander, O. Struve, and Peters, grounded on observations
+made at the three Russian observatories of Dorpat, Abo, and Pulkowa,
+“that the velocity of the motion of the solar system in space is such
+that the sun, with all the bodies which depend upon it, advances
+annually towards the constellation Hercules[17] 1·623 times the radius
+of the earth’s orbit, or 33,550,000 geographical miles. The possible
+error of this last number amounts to 1,733,000 geographical miles, or
+to a _seventh_ of the whole value. We may, then, wager 400,000 to 1
+that the sun has a proper progressive motion, and 1 to 1 that it is
+comprised between the limits of thirty-eight and twenty-nine millions
+of geographical miles.”
+
+  That is, taking 95,000,000 of English miles as the mean radius of
+  the Earth’s orbit, we have 95 × 1·623 = 154·185 millions of miles;
+  and consequently,
+
+                                          English Miles.
+    The velocity of the Solar System      154,185,000 in the year.
+           ”         ”                        422,424 in a day.
+           ”         ”                         17,601 in an hour.
+           ”         ”                            293 in a minute.
+           ”         ”                             57 in a second.
+
+  The Sun and all his planets, primary and secondary, are therefore
+  now in rapid motion round an invisible focus. To that now dark and
+  mysterious centre, from which no ray, however feeble, shines, we
+  may in another age point our telescopes, detecting perchance the
+  great luminary which controls our system and bounds its path: into
+  that vast orbit man, during the whole cycle of his race, may never
+  be allowed to round.--_North-British Review_, No. 16.
+
+
+NATURE OF THE SUN.
+
+M. Arago has found, by experiments with the polariscope, that the light
+of gaseous bodies is natural light when it issues from the burning
+surface; although this circumstance does not prevent its subsequent
+complete polarisation, if subjected to suitable reflections or
+refractions. Hence we obtain _a most simple method of discovering
+the nature of the sun_ at a distance of forty millions of leagues.
+For if the light emanating from the margin of the sun, and radiating
+from the solar substance _at an acute angle_, reach us without having
+experienced any sensible reflections or refractions in its passage
+to the earth, and if it offer traces of polarisation, the sun must
+be _a solid or a liquid body_. But if, on the contrary, the light
+emanating from the sun’s margin give no indications of polarisation,
+the _incandescent_ portion of the sun must be _gaseous_. It is by means
+of such a methodical sequence of observations that we may acquire
+exact ideas regarding the physical constitution of the sun.--_Note to
+Humboldt’s Cosmos_, vol. iii.
+
+
+STRUCTURE OF THE LUMINOUS DISC OF THE SUN.
+
+The extraordinary structure of the _fully luminous_ Disc of the Sun, as
+seen through Sir James South’s great achromatic, in a drawing made by
+Mr. Gwilt, resembles compressed curd, or white almond-soap, or a mass
+of asbestos fibres, lying in a _quaquaversus_ direction, and compressed
+into a solid mass. There can be no illusion in this phenomenon; it
+is seen by every person with good vision, and on every part of the
+sun’s luminous surface or envelope, which is thus shown to be not a
+_flame_, but a soft solid or thick fluid, maintained in an incandescent
+state by subjacent heat, capable of being disturbed by differences of
+temperature, and broken up as we see it when the sun is covered with
+spots or openings in the luminous matter.--_North-British Review_, No.
+16.
+
+  Copernicus named the sun the lantern of the world (_lucerna
+  mundi_); and Theon of Smyrna called it the heart of the universe.
+  The mass of the sun is, according to Encke’s calculation of
+  Sabine’s pendulum formula, 359,551 times that of the earth, or
+  355,499 times that of the earth and moon together; whence the
+  density of the sun is only about ¼ (or more accurately 0·252) that
+  of the earth. The volume of the sun is 600 times greater, and its
+  mass, according to Galle, 738 times greater, than that of all the
+  planets combined. It may assist the mind in conceiving a sensuous
+  image of the magnitude of the sun, if we remember that if the solar
+  sphere were entirely hollowed out, and the earth placed in its
+  centre, there would still be room enough for the moon to describe
+  its orbit, even if the radius of the latter were increased 160,000
+  geographical miles. A railway-engine, moving at the rate of thirty
+  miles an hour, would require 360 years to travel from the earth to
+  the sun. The diameter of the sun is rather more than one hundred
+  and eleven times the diameter of the earth. Therefore the volume or
+  bulk of the sun must be nearly _one million four hundred thousand_
+  times that of the earth. Lastly, if all the bodies composing the
+  solar system were formed into one globe, it would be only about the
+  five-hundredth part of the size of the sun.
+
+
+GREAT SIZE OF THE SUN ON THE HORIZON EXPLAINED.
+
+The dilated size (generally) of the Sun or Moon, when seen near the
+horizon, beyond what they appear to have when high up in the sky, has
+nothing to do with refraction. It is an illusion of the judgment,
+arising from the terrestrial objects interposed, or placed in close
+comparison with them. In that situation we view and judge of them
+as we do of terrestrial objects--in detail, and with an acquired
+attention to parts. Aloft we have no association to guide us, and their
+insulation in the expanse of the sky leads us rather to undervalue
+than to over-rate their apparent magnitudes. Actual measurement with
+a proper instrument corrects our error, without, however, dispelling
+our illusion. By this we learn that the sun, when just on the horizon,
+subtends at our eyes almost exactly the same, and the moon a materially
+_less_, angle than when seen at a greater altitude in the sky, owing to
+its greater distance from us in the former situation as compared with
+the latter.--_Sir John Herschel’s Outlines._
+
+
+TRANSLATORY MOTION OF THE SUN.
+
+This phenomenon is the progressive motion of the centre of gravity of
+the whole solar system in universal space. Its velocity, according
+to Bessel, is probably four millions of miles daily, in a _relative_
+velocity to that of 61 Cygni of at least 3,336,000 miles, or more than
+double the velocity of the revolution of the earth in her orbit round
+the sun. This change of the entire solar system would remain unknown
+to us, if the admirable exactness of our astronomical instruments of
+measurement, and the advancement recently made in the art of observing,
+did not cause our progress towards remote stars to be perceptible,
+like an approximation to the objects of a distant shore in apparent
+motion. The proper motion of the star 61 Cygni, for instance, is so
+considerable, that it has amounted to a whole degree in the course of
+700 years.--_Humboldt’s Cosmos_, vol. i.
+
+
+THE SUN’S LIGHT COMPARED WITH TERRESTRIAL LIGHTS.
+
+Mr. Ponton has by means of a simple monochromatic photometer
+ascertained that a small surface, illuminated by mean solar light, is
+444 times brighter than when it is illuminated by a moderator lamp, and
+1560 times brighter than when it is illuminated by a wax-candle (short
+six in the lb.)--the artificial light being in both instances placed at
+two inches’ distance from the illuminated surface. And three electric
+lights, each equal to 520 wax-candles, will render a small surface as
+bright as when it is illuminated by mean sunshine.
+
+It is thence inferred, that a stratum occupying the entire surface of
+the sphere of which the earth’s distance from the sun is the radius,
+and consisting of three layers of flame, each 1/1000th of an inch
+in thickness, each possessing a brightness equal to that of such an
+electric light, and all three embraced within a thickness of 1/40th of
+an inch, would give an amount of illumination equal in quantity and
+intensity to that of the sun at the distance of 95 millions of miles
+from his centre.
+
+And were such a stratum transferred to the surface of the sun, where it
+would occupy 46,275 times less area, its thickness would be increased
+to 94 feet, and it would embrace 138,825 layers of flame, equal in
+brightness to the electric light; but the same effect might be produced
+by a stratum about nine miles in thickness, embracing 72 millions of
+layers, each having only a brightness equal to that of a wax-candle.[18]
+
+
+ACTINIC POWER OF THE SUN.
+
+Mr. J. J. Waterston, in 1857, made at Bombay some experiments on the
+photographic power of the sun’s direct light, to obtain data in an
+inquiry as to the possibility of measuring the diameter of the sun to
+a very minute fraction of a second, by combining photography with the
+principle of the electric telegraph; the first to measure the element
+space, the latter the element time. The result is that about 1/20000th
+of a second is sufficient exposure to the direct light of the sun to
+obtain a distinct mark on a sensitive collodion plate, when developed
+by the usual processes; and the duration of the sun’s full action on
+any one point is about 1/9000th of a second.
+
+M. Schatt, a young painter of Berlin, after 1500 experiments, succeeded
+in establishing a scale of all the shades of black which the action of
+the sun produces on photographic paper; so that by comparing the shade
+obtained at any given moment on a certain paper with that indicated on
+the scale, the exact force of the sun’s light may be determined.
+
+
+HEATING POWER OF THE SUN.
+
+All moving power has its origin in the rays of the sun. While
+Stephenson’s iron tubular railway-bridge over the Menai Straits, 400
+feet long, bends but half an inch under the heaviest pressure of a
+train, it will bend up an inch and a half from its usual horizontal
+line when the sun shines on it for some hours. The Bunker-Hill
+monument, near Boston, U.S., is higher in the evening than in the
+morning of a sunny day; the little sunbeams enter the pores of the
+stone like so many wedges, lifting it up.
+
+In winter, the Earth is nearer the Sun by about 1/30 than in summer;
+but the rays strike the northern hemisphere more obliquely in winter
+than the other half year.
+
+M. Pouillet has estimated, with singular ingenuity, from a series of
+observations made by himself, that the whole quantity of heat which the
+Earth receives annually from the Sun is such as would be sufficient to
+melt a stratum of ice covering the entire globe forty-six feet deep.
+
+By the action of the sun’s rays upon the earth, vegetables, animals,
+and man, are in their turn supported; the rays become likewise, as
+it were, a store of heat, and “the sources of those great deposits
+of dynamical efficiency which are laid up for human use in our coal
+strata” (_Herschel_).
+
+A remarkable instance of the power of the sun’s rays is recorded at
+Stonehouse Point, Devon, in the year 1828. To lay the foundation of a
+sea-wall the workmen had to descend in a diving-bell, which was fitted
+with convex glasses in the upper part, by which, on several occasions
+in clear weather, the sun’s rays were so concentrated as to burn the
+labourers’ clothes when opposed to the focal point, and this when the
+bell was twenty-five feet under the surface of the water!
+
+
+CAUSE OF DARK COLOUR OF THE SKIN.
+
+Darkness of complexion has been attributed to the sun’s power from the
+age of Solomon to this day,--“Look not upon me, because I am black,
+because the sun hath looked upon me:” and there cannot be a doubt
+that, to a certain degree, the opinion is well founded. The invisible
+rays in the solar beams, which change vegetable colour, and have been
+employed with such remarkable effect in the daguerreotype, act upon
+every substance on which they fall, producing mysterious and wonderful
+changes in their molecular state, man not excepted.--_Mrs. Somerville._
+
+
+EXTREME SOLAR HEAT.
+
+The fluctuation in the sun’s direct heating power amounts to 1/15th,
+which is too considerable a fraction of the whole intensity not
+to aggravate in a serious degree the sufferings of those who are
+exposed to it in thirsty deserts without shelter. The amount of these
+sufferings, in the interior of Australia for instance, are of the
+most frightful kind, and would seem far to exceed what have ever been
+undergone by travellers in the northern deserts of Africa. Thus
+Captain Sturt, in his account of his Australian exploration, says:
+“The ground was almost a molten surface; and if a match accidentally
+fell upon it, it immediately ignited.” Sir John Herschel has observed
+the temperature of the surface soil in South Africa as high as 159°
+Fahrenheit. An ordinary lucifer-match does not ignite when simply
+pressed upon a smooth surface at 212°; but _in the act of withdrawing
+it_ it takes fire, and the slightest friction upon such a surface of
+course ignites it.
+
+
+HOW DR. WOLLASTON COMPARED THE LIGHT OF THE SUN AND THE FIXED STARS.
+
+In order to compare the Light of the Sun with that of a Star, Dr.
+Wollaston took as an intermediate object of comparison the light of a
+candle reflected from a bulb about a quarter of an inch in diameter,
+filled with quicksilver; and seen by one eye through a lens of two
+inches focus, at the same time that the star on the sun’s image,
+_placed at a proper distance_, was viewed by the other eye through a
+telescope. The mean of various trials seemed to show that the light
+of Sirius is equal to that of the sun seen in a glass bulb 1/10th of
+an inch in diameter, at the distance of 210 feet; or that they are in
+the proportion of one to ten thousand millions: but as nearly one half
+of this light is lost by reflection, the real proportion between the
+light from Sirius and the sun is not greater than that of one to twenty
+thousand millions.
+
+
+“THE SUN DARKENED.”
+
+Humboldt selects the following example from historical records as to
+the occurrence of a sudden decrease in the light of the Sun:
+
+  A.D. 33, the year of the Crucifixion. “Now from the sixth hour
+  there was darkness over all the land till the ninth hour” (_St.
+  Matthew_ xxvii. 45). According to _St. Luke_ (xxiii. 45), “the
+  sun was darkened.” In order to explain and corroborate these
+  narrations, Eusebius brings forward an eclipse of the sun in the
+  202d Olympiad, which had been noticed by the chronicler Phlegon
+  of Tralles (_Ideler_, _Handbuch der Mathem. Chronologie_, Bd. ii.
+  p. 417). Wurn, however, has shown that the eclipse which occurred
+  during this Olympiad, and was visible over the whole of Asia
+  Minor, must have happened as early as the 24th of November 29 A.D.
+  The day of the Crucifixion corresponded with the Jewish Passover
+  (_Ideler_, Bd. i. pp. 515-520), on the 14th of the month Nisan, and
+  the Passover was always celebrated at the time of the _full moon_.
+  The sun cannot therefore have been darkened for three hours by the
+  moon. The Jesuit Scheiner thinks the decrease in the light might be
+  ascribed to the occurrence of large sun-spots.
+
+
+THE SUN AND TERRESTRIAL MAGNETISM.
+
+The important influence exerted by the Sun’s body, as a mass, upon
+Terrestrial Magnetism, is confirmed by Sabine in the ingenious
+observation, that the period at which the intensity of the magnetic
+force is greatest, and the direction of the needle most near to the
+vertical line, falls in both hemispheres between the months of October
+and February; that is to say, precisely at the time when the earth is
+nearest to the sun, and moves in its orbit with the greatest velocity.
+
+
+IS THE HEAT OF THE SUN DECREASING?
+
+The Heat of the Sun is dissipated and lost by radiation, and must
+be progressively diminished unless its thermal energy be supplied.
+According to the measurements of M. Pouillet, the quantity of heat
+given out by the sun in a year is equal to that which would be produced
+by the combustion of a stratum of coal seventeen miles in thickness;
+and if the sun’s capacity for heat be assumed equal to that of water,
+and the heat be supposed drawn uniformly from its entire mass, its
+temperature would thereby undergo a diminution of 20·4° Fahr. annually.
+On the other hand, there is a vast store of force in our system capable
+of conversion into heat. If, as is indicated by the small density of
+the sun, and by other circumstances, that body has not yet reached the
+condition of incompressibility, we have in the future approximation of
+its parts a fund of heat, probably quite large enough to supply the
+wants of the human family to the end of its sojourn here. It has been
+calculated that an amount of condensation which would diminish the
+diameter of the sun by only the ten-thousandth part, would suffice to
+restore the heat emitted in 2000 years.
+
+
+UNIVERSAL SUN-DIAL.
+
+Mr. Sharp, of Dublin, exhibited to the British Association in 1849 a
+Dial, consisting of a cylinder set to the day of the month, and then
+elevated to the latitude. A thin plane of metal, in the direction of
+its axis, is then turned by a milled head below it till the shadow is
+a minimum, when a dial on the top shows the hours by one hand, and the
+minutes by another, to the precision of about three minutes.
+
+
+LENGTH OF DAYS AT THE POLES.
+
+During the summer, in the northern hemisphere, places near the North
+Pole are in _continual sunlight_--the sun never sets to them; while
+during that time places near the South Pole never see the sun. When it
+is summer in the southern hemisphere, and the sun shines on the South
+Pole without setting, the North Pole is entirely deprived of his light.
+Indeed, at the Poles there is but _one day and one night_; for the sun
+shines for six months together on one Pole, and the other six months on
+the other Pole.
+
+
+HOW THE DISTANCE OF THE SUN IS ASCERTAINED BY THE YARD-MEASURE.
+
+Professor Airy, in his _Six Lectures on Astronomy_, gives a masterly
+analysis of a problem of considerable intricacy, viz. the determination
+of the parallax of the sun, and consequently of his distance, by
+observations of the transit of Venus, the connecting link between
+measures upon the earth’s surface and the dimensions of our system.
+The further step of investigating the parallax, and consequently the
+distance of the fixed stars (where that is practicable), is also
+elucidated; and the author, with evident satisfaction, thus sums up the
+several steps:
+
+  By means of a yard-measure, a base-line in a survey was measured;
+  from this, by the triangulations and computations of a survey,
+  an arc of meridian on the earth was measured; from this, with
+  proper observations with the zenith sector, the surveys being also
+  repeated on different parts of the earth, the earth’s form and
+  dimensions were ascertained; from these, and a previous independent
+  knowledge of the proportions of the distances of the earth and
+  other planets from the sun, with observations of the transit of
+  Venus, the sun’s distance is determined; and from this, with
+  observations leading to the parallax of the stars, the distance
+  of the stars is determined. And _every step in the process can be
+  distinctly referred to its basis, that is, the yard-measure_.
+
+
+HOW THE TIDES ARE PRODUCED BY THE SUN AND MOON.
+
+Each of these bodies excites, by its attraction upon the waters of the
+sea, two gigantic waves, which flow in the same direction round the
+world as the attracting bodies themselves apparently do. The two waves
+of the moon, on account of her greater nearness, are about 3½ times as
+large as those excited by the sun. One of these waves has its crest on
+the quarter of the earth’s surface which is turned towards the moon;
+the other is at the opposite side. Both these quarters possess the flow
+of the tide, while the regions which lie between have the ebb. Although
+in the open sea the height of the tide amounts to only about three
+feet, and only in certain narrow channels, where the moving water is
+squeezed together, rises to thirty feet, the might of the phenomenon
+is nevertheless manifest from the calculation of Bessel, according to
+which a quarter of the earth covered by the sea possesses during the
+flow of the tide about 25,000 cubic miles of water more than during the
+ebb; and that, therefore, such a mass of water must in 6¼ hours flow
+from one quarter of the earth to the other.--_Professor Helmholtz._
+
+
+SPOTS ON THE SUN.
+
+Sir John Herschel describes these phenomena, when watched from day to
+day, or even from hour to hour, as appearing to enlarge or contract,
+to change their forms, and at length disappear altogether, or to break
+out anew in parts of the surface where none were before. Occasionally
+they break up or divide into two or more. The scale on which their
+movements takes place is immense. A single second of angular measure,
+as seen from the earth, corresponds on the sun’s disc to 461 miles; and
+a circle of this diameter (containing therefore nearly 167,000 square
+miles) is the least space which can be distinctly discerned on the sun
+as a _visible area_. Spots have been observed, however, whose linear
+diameter has been upwards of 45,000 miles; and even, if some records
+are to be trusted, of very much greater extent. That such a spot should
+close up in six weeks time (for they seldom last much longer), its
+borders must approach at the rate of more than 1000 miles a-day.
+
+The same astronomer saw at the Cape of Good Hope, on the 29th March
+1837, a solar spot occupying an area of near _five square minutes_,
+equal to 3,780,000,000 square miles. “The black centre of the spot of
+May 25th, 1837 (not the tenth part of the preceding one), would have
+allowed the globe of our earth to drop through it, leaving a thousand
+miles clear of contact on all sides of that tremendous gulf.” For such
+an amount of disturbance on the sun’s atmosphere, what reason can be
+assigned?
+
+The Rev. Mr. Dawes has invented a peculiar contrivance, by means of
+which he has been enabled to scrutinise, under high magnifying power,
+minute portions of the solar disc. He places a metallic screen, pierced
+with a very small hole, in the focus of the telescope, where the image
+of the sun is formed. A small portion only of the image is thus allowed
+to pass through, so that it may be examined by the eye-piece without
+inconveniencing the observer by heat or glare. By this arrangement,
+Mr. Dawes has observed peculiarities in the constitution of the sun’s
+surface which are discernible in no other way.
+
+Before these observations, the dark spots seen on the sun’s surface
+were supposed to be portions of the solid body of the sun, laid bare to
+our view by those immense fluctuations in the luminous regions of its
+atmosphere to which it appears to be subject. It now appears that these
+dark portions are only an additional and inferior stratum of a very
+feebly luminous or illuminated portion of the sun’s atmosphere. This
+again in its turn Mr. Dawes has frequently seen pierced with a smaller
+and usually much more rounded aperture, which would seem at last to
+afford a view of the real solar surface of most intense blackness.
+
+M. Schwabe, of Dessau, has discovered that the abundance or paucity
+of spots displayed by the sun’s surface is subject to a law of
+periodicity. This has been confirmed by M. Wolf, of Berne, who shows
+that the period of these changes, from minimum to minimum, is 11 years
+and 11-hundredths of a year, being exactly at the rate of nine periods
+per century, the last year of each century being a year of minimum. It
+is strongly corroborative of the correctness both of M. Wolf’s period
+and also of the periodicity itself, that of all the instances of the
+appearance of spots on the sun recorded in history, even before the
+invention of the telescope, or of remarkable deficiencies in the sun’s
+light, of which there are great numbers, only two are found to deviate
+as much as two years from M. Wolf’s epochs. Sir William Herschel
+observed that the presence or absence of spots had an influence on the
+temperature of the seasons; his observations have been fully confirmed
+by M. Wolf. And, from an examination of the chronicles of Zurich from
+A.D. 1000 to A.D. 1800, he has come to the conclusion “that years rich
+in solar spots are in general drier and more fruitful than those of an
+opposite character; while the latter are wetter and more stormy than
+the former.”
+
+The most extraordinary fact, however, in connection with the spots on
+the sun’s surface, is the singular coincidence of their periods with
+those great disturbances in the magnetic system of the earth to which
+the epithet of “magnetic storms” has been affixed.
+
+  These disturbances, during which the magnetic needle is greatly
+  and universally agitated (not in a particular limited locality,
+  but at one and the same instant of time over whole continents, or
+  even over the whole earth), are found, so far as observation has
+  hitherto extended, to maintain a parallel, both in respect of their
+  frequency of occurrence and intensity in successive years, with the
+  abundance and magnitude of the spots in the same years, too close
+  to be regarded as fortuitous. The coincidence of the epochs of
+  maxima and minima in the two series of phenomena amounts, indeed,
+  to identity; a fact evidently of most important significance, but
+  which neither astronomical nor magnetic science is yet sufficiently
+  advanced to interpret.--_Herschel’s Outlines._
+
+The signification and connection of the above varying phenomena
+(Humboldt maintains) can never be manifested in their entire importance
+until an uninterrupted series of representations of the sun’s spots
+can be obtained by the aid of mechanical clock-work and photographic
+apparatus, as the result of prolonged observations during the many
+months of serene weather enjoyed in a tropical climate.
+
+  M. Schwabe has thus distinguished himself as an indefatigable
+  observer of the sun’s spots, for his researches received the Royal
+  Astronomical Society’s Medal in 1857. “For thirty years,” said
+  the President at the presentation, “never has the sun exhibited
+  his disc above the horizon of Dessau without being confronted
+  by Schwabe’s imperturbable telescope; and that appears to have
+  happened on an average about 300 days a-year. So, supposing that
+  he had observed but once a-day, he has made 9000 observations,
+  in the course of which he discovered about 4700 groups. This is,
+  I believe, an instance of devoted persistence unsurpassed in
+  the annals of astronomy. The energy of one man has revealed a
+  phenomenon that had eluded the suspicion of astronomers for 200
+  years.”
+
+
+HAS THE MOON AN ATMOSPHERE?
+
+The Moon possesses neither Sea nor Atmosphere of appreciable
+extent. Still, as a negative, in such case, is relative only to
+the capabilities of the instruments employed, the search for the
+indications of a lunar atmosphere has been renewed with fresh
+augmentation of telescopic power. Of such indications, the most
+delicate, perhaps, are those afforded by the occultation of a planet
+by the moon. The occultation of Jupiter, which took place on January
+2, 1857, was observed with this reference, and is said to have
+exhibited no _hesitation_, or change of form or brightness, such as
+would be produced by the refraction or absorption of an atmosphere. As
+respects the sea, if water existed on the moon’s surface, the sun’s
+light reflected from it should be completely polarised at a certain
+elongation of the moon from the sun; and no traces of such light have
+been observed.
+
+MM. Baer and Maedler conclude that the moon is not entirely without
+an atmosphere, but, owing to the smallness of her mass, she is
+incapacitated from holding an extensive covering of gas; and they add,
+“it is possible that this weak envelope may sometimes, through local
+causes, in some measure dim or condense itself.” But if any atmosphere
+exists on our satellite, it must be, as Laplace says, more attenuated
+than what is termed a vacuum in an air-pump.
+
+Mr. Hopkins thinks that if there be any lunar atmosphere, it must
+be very rare in comparison with the terrestrial atmosphere, and
+inappreciable to the kind of observation by which it has been tested;
+yet the absence of any refraction of the light of the stars during
+occultation is a very refined test. Mr. Nasmyth observes that “the
+sudden disappearance of the stars behind the moon, without any change
+or diminution of her brilliancy, is one of the most beautiful phenomena
+that can be witnessed.”
+
+Sir John Herschel observes: The fact of the moon turning always the
+same face towards the earth is, in all probability, the result of an
+elongation of its figure in the direction of a line joining the centres
+of both the bodies, acting conjointly with a non-coincidence of its
+centre of gravity with its centre of symmetry.
+
+If to this we add the supposition that the substance of the moon is
+not homogeneous, and that some considerable preponderance of weight
+is placed excentrically in it, it will be easily apprehended that the
+portion of its surface nearer to that heavier portion of its solid
+content, under all the circumstances of the moon’s rotation, will
+permanently occupy the situation most remote from the earth.
+
+  In what regards its assumption of a definite level, air obeys
+  precisely the same hydrostatical laws as water. The lunar
+  atmosphere would rest upon the lunar ocean, and form in its basin a
+  lake of air, whose upper portions at an altitude such as we are now
+  contemplating would be of excessive tenuity, especially should the
+  provision of air be less abundant in proportion than our own. It by
+  no means follows, then, from the absence of visible indications of
+  water or air on this side of the moon, that the other is equally
+  destitute of them, and equally unfitted for maintaining animal or
+  vegetable life. Some slight approach to such a state of things
+  actually obtains on the earth itself. Nearly all the land is
+  collected in one of its hemispheres, and much the larger portion
+  of the sea in the opposite. There is evidently an excess of heavy
+  material vertically beneath the middle of the Pacific; while not
+  very remote from the point of the globe diametrically opposite
+  rises the great table-land of India and the Himalaya chain, on the
+  summits of which the air has not more than a third of the density
+  it has on the sea-level, and from which animated existence is for
+  ever excluded.--_Herschel’s Outlines_, 5th edit.
+
+
+LIGHT OF THE MOON.
+
+The actual illumination of the lunar surface is not much superior to
+that of weathered sandstone-rock in full sunshine. Sir John Herschel
+has frequently compared the moon setting behind the gray perpendicular
+façade of the Table Mountain at the Cape of Good Hope, illuminated
+by the sun just risen from the opposite quarter of the horizon, when
+it has been scarcely distinguishable in brightness from the rock in
+contact with it. The sun and moon being nearly at equal altitudes, and
+the atmosphere perfectly free from cloud or vapour, its effect is alike
+on both luminaries.
+
+
+HEAT OF MOONLIGHT.
+
+M. Zantedeschi has proved, by a long series of experiments in the
+Botanic Gardens at Venice, Florence, and Padua, that, contrary to the
+general opinion, the diffused rays of moonlight have an influence
+upon the organs of plants, as the Sensitive Plant and the _Desmodium
+gyrans_. The influence was feeble compared with that of the sun; but
+the action is left beyond further question.
+
+Melloni has proved that the rays of the Moon give out a slight degree
+of Heat (see _Things not generally Known_, p. 7); and Professor Piazzi
+Smyth, from a point of the Peak of Teneriffe 8840 feet above the
+sea-level, has found distinctly perceptible the heat radiated from the
+moon, which has been so often sought for in vain in a lower region.
+
+
+SCENERY OF THE MOON.
+
+By means of the telescope, mountain-peaks are distinguished in the
+ash-gray light of the larger spots and isolated brightly-shining points
+of the moon, even when the disc is already more than half illuminated.
+Lambert and Schroter have shown that the extremely variable intensity
+of the ash-gray light of the moon depends upon the greater or less
+degree of reflection of the sunlight which falls upon the earth,
+according as it is reflected from continuous continental masses, full
+of sandy deserts, grassy steppes, tropical forests, and barren rocky
+ground, or from large ocean surfaces. Lambert made the remarkable
+observation (14th of February 1774) of a change of the ash-coloured
+moonlight into an olive-green colour bordering upon yellow. “The moon,
+which then stood vertically over the Atlantic Ocean, received upon its
+right side the green terrestrial light which is reflected towards her
+when the sky is clear by the forest districts of South America.”
+
+Plutarch says distinctly, in his remarkable work _On the Face in the
+Moon_, that we may suppose the _spots_ to be partly deep chasms and
+valleys, partly mountain-peaks, which cast long shadows, like Mount
+Athos, whose shadow reaches Lemnos. The spots cover about two-fifths
+of the whole disc. In a clear atmosphere, and under favourable
+circumstances in the position of the moon, some of the spots are
+visible to the naked eye; as the edge of the Apennines, the dark
+elevated plain Grimaldus, the enclosed _Mare Crisium_, and Tycho,
+crowded round with numerous mountain ridges and craters.
+
+Professor Alexander remarks, that a map of the eastern hemisphere,
+taken with the Bay of Bengal in the centre, would bear a striking
+resemblance to the face of the moon presented to us. The dark portions
+of the moon he considers to be continental elevations, as shown by
+measuring the average height of mountains above the dark and the light
+portions of the moon.
+
+The surface of the moon can be as distinctly seen by a good telescope
+magnifying 1000 times, as it would be if not more than 250 miles
+distant.
+
+
+LIFE IN THE MOON.
+
+A circle of one second in diameter, as seen from the earth, on the
+surface of the moon contains about a square mile. Telescopes,
+therefore, must be greatly improved before we could expect to see signs
+of inhabitants, as manifested by edifices or changes on the surface
+of the soil. It should, however, be observed, that owing to the small
+density of the materials of the moon, and the comparatively feeble
+gravitation of bodies on her surface, muscular force would there go six
+times as far in overcoming the weight of materials as on the earth.
+Owing to the want of air, however, it seems impossible that any form
+of life analogous to those on earth can subsist there. No appearance
+indicating vegetation, or the slightest variation of surface which can
+in our opinion fairly be ascribed to change of season, can any where be
+discerned.--_Sir John Herschel’s Outlines._
+
+
+THE MOON SEEN THROUGH LORD ROSSE’S TELESCOPE.
+
+In 1846, the Rev. Dr. Scoresby had the gratification of observing
+the Moon through the stupendous telescope constructed by Lord Rosse
+at Parsonstown. It appeared like a globe of molten silver, and every
+object to the extent of 100 yards was quite visible. Edifices,
+therefore, of the size of York Minster, or even of the ruins of Whitby
+Abbey, might be easily perceived, if they had existed. But there was
+no appearance of any thing of that nature; neither was there any
+indication of the existence of water, or of an atmosphere. There
+were a great number of extinct volcanoes, several miles in breadth;
+through one of them there was a line of continuance about 150 miles in
+length, which ran in a straight direction, like a railway. The general
+appearance, however, was like one vast ruin of nature; and many of the
+pieces of rock driven out of the volcanoes appeared to lie at various
+distances.
+
+
+MOUNTAINS IN THE MOON.
+
+By the aid of telescopes, we discern irregularities in the surface of
+the moon which can be no other than mountains and valleys,--for this
+plain reason, that we see the shadows cast by the former in the exact
+proportion as to length which they ought to have when we take into
+account the inclinations of the sun’s rays to that part of the moon’s
+surface on which they stand. From micrometrical measurements of the
+lengths of the shadows of the more conspicuous mountains, Messrs. Baer
+and Maedler have given a list of heights for no less than 1095 lunar
+mountains, among which occur all degrees of elevation up to 22,823
+British feet, or about 1400 feet higher than Chimborazo in the Andes.
+
+If Chimborazo were as high in proportion to the earth’s diameter as
+a mountain in the moon known by the name of Newton is to the moon’s
+diameter, its peak would be more than sixteen miles high.
+
+Arago calls to mind, that with a 6000-fold magnifying power, which
+nevertheless could not be applied to the moon with proportionate
+results, the mountains upon the moon would appear to us just as Mont
+Blanc does to the naked eye when seen from the Lake of Geneva.
+
+We sometimes observe more than half the surface of the moon, the
+eastern and northern edges being more visible at one time, and the
+western or southern at another. By means of this libration we are
+enabled to see the annular mountain Malapert (which occasionally
+conceals the moon’s south pole), the arctic landscape round the crater
+of Gioja, and the large gray plane near Endymion, which conceals in
+superficial extent the _mare vaporum_.
+
+Three-sevenths of the moon are entirely concealed from our observation;
+and must always remain so, unless some new and unexpected disturbing
+causes come into play.--_Humboldt._
+
+  The first object to which Galileo directed his telescope was the
+  mountainous parts of the moon, when he showed how their summits
+  might be measured: he found in the moon some circular districts
+  surrounded on all sides by mountains similar to the form of
+  Bohemia. The measurements of the mountains were made by the method
+  of the tangents of the solar ray. Galileo, as Helvetius did still
+  later, measured the distance of the summit of the mountains from
+  the boundary of the illuminated portion at the moment when the
+  mountain summit was first struck by the solar ray. Humboldt found
+  no observations of the lengths of the shadows of the mountains:
+  the summits were “much higher than the mountains on our earth.”
+  The comparison is remarkable, since, according to Riccioli,
+  very exaggerated ideas of the height of our mountains were then
+  entertained. Galileo like all other observers up to the close of
+  the eighteenth century, believed in the existence of many seas and
+  of a lunar atmosphere.
+
+
+THE MOON AND THE WEATHER.
+
+The only influence of the Moon on the Weather of which we have any
+decisive evidence is the tendency to disappearance of clouds under the
+full moon, which Sir John Herschel refers to its heat being much more
+readily absorbed in traversing transparent media than direct solar
+heat, and being extinguished in the upper regions of our atmosphere,
+never reaches the surface of the atmosphere at all.
+
+
+THE MOON’S ATTRACTION.
+
+Mr. G. P. Bond of Cambridge, by some investigations to ascertain
+whether the Attraction of the Moon has any effect upon the motion of
+a pendulum, and consequently upon the rate of a clock, has found the
+last to be changed to the amount of 9/1000 of a second daily. At
+the equator the moon’s attraction changes the weight of a body only
+1/7000000 of the whole; yet this force is sufficient to produce the
+vast phenomena of the tides!
+
+It is no slight evidence of the importance of analysis, that Laplace’s
+perfect theory of tides has enabled us in our astronomical ephemerides
+to predict the height of spring-tides at the periods of new and full
+moon, and thus put the inhabitants of the sea on their guard against
+the increased danger attending the lunar revolutions.
+
+
+MEASURING THE EARTH BY THE MOON.
+
+As the form of the Earth exerts a powerful influence on the motion
+of other cosmical bodies, and especially on that of its neighbouring
+satellite, a more perfect knowledge of the motion of the latter will
+enable us reciprocally to draw an inference regarding the figure of
+the earth. Thus, as Laplace ably remarks: “an astronomer, without
+leaving his observatory, may, by a comparison of lunar theory with true
+observations, not only be enabled to determine the form and size of
+the earth, but also its distance from the sun and moon; results that
+otherwise could only be arrived at by long and arduous expeditions
+to the most remote parts of both hemispheres.” The compression which
+may be inferred from lunar inequalities affords an advantage not
+yielded by individual measurements of degrees or experiments with the
+pendulum, since it gives a mean amount which is referable to the whole
+planet.--_Humboldt’s Cosmos_, vol. i.
+
+The distance of the moon from the earth is about 240,000 miles; and
+if a railway-carriage were to travel at the rate of 1000 miles a-day,
+it would be eight months in reaching the moon. But that is nothing
+compared with the length of time it would occupy a locomotive to reach
+the sun from the earth: if travelling at the rate of 1000 miles a-day,
+it would require 260 years to reach it.
+
+
+CAUSE OF ECLIPSES.
+
+As the Moon is at a very moderate distance from us (astronomically
+speaking), and is in fact our nearest neighbour, while the sun and
+stars are in comparison immensely beyond it, it must of necessity
+happen that at one time or other it must _pass over_, and _occult_ or
+_eclipse_, every star or planet within its zone, and, as seen from
+the _surface_ of the earth, even somewhat beyond it. Nor is the sun
+itself exempt from being thus hidden whenever any part of the moon’s
+disc, in this her tortuous course, comes to _overlap_ any part of the
+space occupied in the heavens by that luminary. On these occasions
+is exhibited the most striking and impressive of all the occasional
+phenomena of astronomy, an _Eclipse of the Sun_, in which a greater or
+less portion, or even in some conjunctures the whole of its disc, is
+obscured, and, as it were, obliterated, by the superposition of that
+of the moon, which appears upon it as a circularly-terminated black
+spot, producing a temporary diminution of daylight, or even nocturnal
+darkness, so that the stars appear as if at midnight.--_Sir John
+Herschel’s Outlines._
+
+
+VAST NUMBERS IN THE UNIVERSE.
+
+The number of telescopic stars in the Milky Way uninterrupted by
+any nebulæ is estimated at 18,000,000. To compare this number with
+something analogous, Humboldt calls attention to the fact, that there
+are not in the whole heavens more than about 8000 stars, between
+the first and the sixth magnitudes, visible to the naked eye. The
+barren astonishment excited by numbers and dimensions in space when
+not considered with reference to applications engaging the mental
+and perceptive powers of man, is awakened in both extremes of the
+universe--in the celestial bodies as in the minutest animalcules. A
+cubic inch of the polishing slate of Bilin contains, according to
+Ehrenberg, 40,000 millions of the siliceous shells of Galionellæ.
+
+
+FOR WHAT PURPOSE WERE THE STARS CREATED?
+
+Surely not (says Sir John Herschel) to illuminate _our_ nights, which
+an additional moon of the thousandth part of the size of our own
+would do much better; nor to sparkle as a pageant void of meaning and
+reality, and bewilder us among vain conjectures. Useful, it is true,
+they are to man as points of exact and permanent reference; but he must
+have studied astronomy to little purpose, who can suppose man to be the
+only object of his Creator’s care, or who does not see in the vast and
+wonderful apparatus around us provision for other races of animated
+beings. The planets derive their light from the sun; but that cannot be
+the case with the stars. These doubtless, then, are themselves suns;
+and may perhaps, each in its sphere, be the presiding centre round
+which other planets, or bodies of which we can form no conception from
+any analogy offered by our own system, are circulating.[19]
+
+
+NUMBER OF STARS.
+
+Various estimates have been hazarded on the Number of Stars throughout
+the whole heavens visible to us by the aid of our colossal telescopes.
+Struve assumes for Herschel’s 20-feet reflector, that a magnifying
+power of 180 would give 5,800,000 for the number of stars lying within
+the zones extending 30° on either side of the equator, and 20,374,000
+for the whole heavens. Sir William Herschel conjectured that 18,000,000
+of stars in the Milky Way might be seen by his still more powerful
+40-feet reflecting telescope.--_Humboldt’s Cosmos_, vol. iii.
+
+The assumption that the extent of the starry firmament is literally
+infinite has been made by Dr. Olbers the basis of a conclusion that the
+celestial spaces are in some slight degree deficient in _transparency_;
+so that all beyond a certain distance is and must remain for ever
+unseen, the geometrical progression of the extinction of light far
+outrunning the effect of any conceivable increase in the power of
+our telescopes. Were it not so, it is argued that every part of the
+celestial concave ought to shine with the brightness of the solar disc,
+since no visual ray could be so directed as not, in some point or other
+of its infinite length, to encounter such a disc.--_Edinburgh Review_,
+Jan. 1848.
+
+
+STARS THAT HAVE DISAPPEARED.
+
+Notwithstanding the great accuracy of the catalogued positions of
+telescopic fixed stars and of modern star-maps, the certainty of
+conviction that a star in the heavens has actually disappeared since
+a certain epoch can only be arrived at with great caution. Errors of
+actual observation, of reduction, and of the press, often disfigure the
+very best catalogues. The disappearance of a heavenly body from the
+place in which it had been before distinctly seen, may be the result
+of its own motion as much as of any such diminution of its photometric
+process as would render the waves of light too weak to excite our
+organs of sight. What we no longer see, is not necessarily annihilated.
+The idea of destruction or combustion, as applied to disappearing
+stars, belongs to the age of Tycho Brahe. Even Pliny makes it a
+question. The apparent eternal cosmical alternation of existence and
+destruction is not annihilation; it is merely the transition of matter
+into new forms, into combinations which are subject to new processes.
+Dark cosmical bodies may by a renewed process of light again become
+luminous.--_Humboldt’s Cosmos_, vol. iii.
+
+
+THE POLE-STAR FOUR THOUSAND YEARS AGO.
+
+Sir John Herschel, in his _Outlines of Astronomy_, thus shows the
+changes in the celestial pole in 4000 years:
+
+  At the date of the erection of the Pyramid of Gizeh, which precedes
+  the present epoch by nearly 4000 years, the longitudes of all the
+  stars were less by 55° 45′ than at present. Calculating from
+  this datum the place of the pole of the heavens among the stars,
+  it will be found to fall near α Draconis; its distance from that
+  star being 3° 44′ 25″. This being the most conspicuous star in
+  the immediate neighbourhood, was therefore the Pole Star of that
+  epoch. The latitude of Gizeh being just 30° north, and consequently
+  the altitude of the North Pole there also 30°, it follows that
+  the star in question must have had at its lowest culmination at
+  Gizeh an altitude of 25° 15′ 35″. Now it is a remarkable fact,
+  that of the nine pyramids still existing at Gizeh, six (including
+  all the largest) have the narrow passages by which alone they can
+  be entered (all which open out on the northern faces of their
+  respective pyramids) inclined to the horizon downwards at angles
+  the mean of which is 26° 47′. At the bottom of every one of these
+  passages, therefore, the Pole Star must have been visible at its
+  lower culmination; a circumstance which can hardly be supposed
+  to have been unintentional, and was doubtless connected (perhaps
+  superstitiously) with the astronomical observations of that star,
+  of whose proximity to the pole at the epoch of the erection of
+  these wonderful structures we are thus furnished with a monumental
+  record of the most imperishable nature.
+
+
+THE PLEIADES.
+
+The Pleiades prove that, several thousand years ago even as now,
+stars of the seventh magnitude were invisible to the naked eye of
+average visual power. The group consists of seven stars, of which six
+only, of the third, fourth, and fifth magnitudes, could be readily
+distinguished. Of these Ovid says (_Fast._ iv. 170):
+
+    “Quæ septem dici, sex tamen esse solent.”
+
+Aratus states there were only six stars visible in the Pleiades.
+
+One of the daughters of Atlas, Merope, the only one who was wedded to
+a mortal, was said to have veiled herself for very shame and to have
+disappeared. This is probably the star of the seventh magnitude, which
+we call Celæne; for Hipparchus, in his commentary on Aratus, observes
+that on clear moonless nights _seven stars_ may actually be seen.
+
+The Pleiades were doubtless known to the rudest nations from the
+earliest times; they are also called the _mariner’s stars_. The name is
+from πλεῖν (_plein_), ‘to sail.’ The navigation of the Mediterranean
+lasted from May to the beginning of November, from the early rising
+to the early setting of the Pleiades. In how many beautiful effusions
+of poetry and sentiment has “the Lost Pleiad” been deplored!--and, to
+descend to more familiar illustration of this group, the “Seven Stars,”
+the sailors’ favourites, and a frequent river-side public-house sign,
+may be traced to the Pleiades.
+
+
+CHANGE OF COLOUR IN THE STARS.
+
+The scintillation or twinkling of the stars is accompanied by
+variations of colour, which have been remarked from a very early age.
+M. Arago states, upon the authority of M. Babinet, that the name of
+Barakesch, given by the Arabians to Sirius, signifies _the star of
+a thousand colours_; and Tycho Brahe, Kepler, and others, attest to
+similar change of colour in twinkling. Even soon after the invention
+of the telescope, Simon Marius remarked that by removing the eye-piece
+of the telescope the images of the stars exhibited rapid fluctuations
+of brightness and colour. In 1814 Nicholson applied to the telescope a
+smart vibration, which caused the image of the star to be transformed
+into a curved line of light returning into itself, and diversified by
+several colours; each colour occupied about a third of the whole length
+of the curve, and by applying ten vibrations in a second, the light of
+Sirius in that time passed through thirty changes of colour. Hence the
+stars in general shine only by a portion of their light, the effect of
+twinkling being to diminish their brightness. This phenomenon M. Arago
+explains by the principle of the interference of light.
+
+Ptolemy is said to have noted Sirius as a _red_ star, though it is now
+white. Sirius twinkles with red and blue light, and Ptolemy’s eyes,
+like those of several other persons, may have been more sensitive to
+the _red_ than to the _blue_ rays.--_Sir David Brewster’s More Worlds
+than One_, p. 235.
+
+Some of the double stars are of very different and dissimilar colours;
+and to the revolving planetary bodies which apparently circulate around
+them, a day lightened by a red light is succeeded by, not a night, but
+a day equally brilliant, though illuminated only by a green light.
+
+
+DISTANCE OF THE NEAREST FIXED STAR FROM THE EARTH.
+
+Sir John Herschel wrote in 1833: “What is the distance of the nearest
+fixed star? What is the scale on which our visible firmament is
+constructed? And what proportion do its dimensions bear to those of our
+own immediate system? To this, however, astronomy has hitherto proved
+unable to supply an answer. All we know on this subject is negative.”
+To these questions, however, an answer can now be given. Slight
+changes of position of some of the stars, called parallax, have been
+distinctly observed and measured; and among these stars No. 61 Cygni of
+Flamstead’s catalogue has a parallax of 5″, and that of α Centauri has
+a proper motion of 4″ per annum.
+
+The same astronomer states that each second of parallax indicates a
+distance of 20 billions of miles, or 3¼ years’ journey of light. Now
+the light sent to us by the sun, as compared with that sent by Sirius
+and α Centauri, is about 22 thousand millions to 1. “Hence, from the
+parallax assigned above to that star, it is easy to conclude that
+its intrinsic splendour, as compared with that of our sun at equal
+distances, is 2·3247, that of the sun being unity. The light of Sirius
+is four times that of α Centauri, and its parallax only 0·15″. This,
+in effect, ascribes to it an intrinsic splendour equal to 96·63 times
+that of α Centauri, and therefore 224·7 times that of our sun.”
+
+This is justly regarded as one of the most brilliant triumphs of
+astronomical science, for the delicacy of the investigation is
+almost inconceivable; yet the reasoning is as unimpeachable as the
+demonstration of a theorem of Euclid.
+
+
+LIGHT OF A STAR SIXTEENFOLD THAT OF THE SUN.
+
+The bright star in the constellation of the Lyre, termed Vega, is the
+brightest in the northern hemisphere; and the combined researches of
+Struve, father and son, have found that the distance of this star from
+the earth is no less than 130 billions of miles! Light travelling
+at the rate of 192 thousand miles in a second consequently occupies
+twenty-one years in passing from this star to the earth. Now it has
+been found, by comparing the light of Vega with the light of the
+sun, that if the latter were removed to the distance of 130 billions
+of miles, his apparent brightness would not amount to more than the
+sixteenth part of the apparent brightness of Vega. We are therefore
+warranted in concluding that the light of Vega is equal to that of
+sixteen suns.
+
+
+DIVERSITIES OF THE PLANETS.
+
+In illustration of the great diversity of the physical peculiarities
+and probable condition of the planets, Sir John Herschel describes
+the intensity of solar radiation as nearly seven times greater on
+Mercury than on the earth, and on Uranus 330 times less; the proportion
+between the two extremes being that of upwards of 2000 to 1. Let any
+one figure to himself, (adds Sir John,) the condition of our globe
+were the sun to be septupled, to say nothing of the greater ratio; or
+were it diminished to a seventh, or to a 300th of its actual power!
+Again, the intensity of gravity, or its efficacy in counteracting
+muscular power and repressing animal activity, on Jupiter is nearly
+two-and-a-half times that on the earth; on Mars not more than one-half;
+on the moon one-sixth; and on the smaller planets probably not more
+than one-twentieth; giving a scale of which the extremes are in the
+proportion of sixty to one. Lastly, the density of Saturn hardly
+exceeds one-eighth of the mean density of the earth, so that it must
+consist of materials not much heavier than cork.
+
+  Jupiter is eleven times, Saturn ten times, Uranus five times, and
+  Neptune nearly six times, the diameter of our earth.
+
+  These four bodies revolve in space at such distances from the sun,
+  that if it were possible to start thence for each in succession,
+  and to travel at the railway speed of 33 miles per hour, the
+  traveller would reach
+
+    Jupiter in  1712 years
+    Saturn      3113   ”
+    Uranus      6226   ”
+    Neptune     9685   ”
+
+  If, therefore, a person had commenced his journey at the period of
+  the Christian era, he would now have to travel nearly 1300 years
+  before he would arrive at the planet Saturn; more than 4300 years
+  before he would reach Uranus; and no less than 7800 years before he
+  could reach the orbit of Neptune.
+
+  Yet the light which comes to us from these remote confines of the
+  solar system first issued from the sun, and is then reflected
+  from the surface of the planet. When the telescope is turned
+  towards Neptune, the observer’s eye sees the object by means of
+  light that issued from the sun eight hours before, and which
+  since then has passed nearly twice through that vast space which
+  railway speed would require almost a century of centuries to
+  accomplish.--_Bouvier’s Familiar Astronomy._
+
+
+GRAND RESULTS OF THE DISCOVERY OF JUPITER’S SATELLITES.
+
+This discovery, one of the first fruits of the invention of the
+telescope, and of Galileo’s early and happy idea of directing its
+newly-found powers to the examination of the heavens, forms one of
+the most memorable epochs in the history of astronomy. The first
+astronomical solution of the great problem of _the longitude_,
+practically the most important for the interests of mankind which has
+ever been brought under the dominion of strict scientific principles,
+dates immediately from this discovery. The final and conclusive
+establishment of the Copernican system of astronomy may also be
+considered as referable to the discovery and study of this exquisite
+miniature system, in which the laws of the planetary motions, as
+ascertained by Kepler, and specially that which connects their periods
+and distances, were specially traced, and found to be satisfactorily
+maintained. And (as if to accumulate historical interest on this point)
+it is to the observation of the eclipses of Jupiter’s satellites
+that we owe the grand discovery of the aberration of light, and the
+consequent determination of the enormous velocity of that wonderful
+element--192,000 miles per second. Mr. Dawes, in 1849, first noticed
+the existence of round, well-defined, bright spots on the belts of
+Jupiter. They vary in situation and number, as many as ten having been
+seen on one occasion. As the belts of Jupiter have been ascribed to the
+existence of currents analogous to our trade-winds, causing the body of
+Jupiter to be visible through his cloudy atmosphere, Sir John Herschel
+conjectures that those bright spots may possibly be insulated masses
+of clouds of local origin, similar to the cumuli which sometimes cap
+ascending columns of vapour in our atmosphere.
+
+It would require nearly 1300 globes of the size of our earth to make
+one of the bulk of Jupiter. A railway-engine travelling at the rate of
+thirty-three miles an hour would travel round the earth in a month,
+but would require more than eleven months to perform a journey round
+Jupiter.
+
+
+WAS SATURN’S RING KNOWN TO THE ANCIENTS?
+
+In Maurice’s _Indian Antiquities_ is an engraving of Sani, the Saturn
+of the Hindoos, taken from an image in a very ancient pagoda, which
+represents the deity encompassed by a _ring_ formed of two serpents.
+Hence it is inferred that the ancients were acquainted with the
+existence of the ring of Saturn.
+
+Arago mentions the remarkable fact of the ring and fourth satellite of
+Saturn having been seen by Sir W. Herschel with his smaller telescope
+by the naked eye, without any eye-piece.
+
+The first or innermost of Saturn’s satellites is nearer to the central
+body than any other of the secondary planets. Its distance from the
+centre of Saturn is 80,088 miles; from the surface of the planet
+47,480 miles; and from the outmost edge of the ring only 4916 miles.
+The traveller may form to himself an estimate of the smallness of
+this amount by remembering the statement of the well-known navigator,
+Captain Beechey, that he had in three years passed over 72,800 miles.
+
+According to very recent observations, Saturn’s ring is divided into
+_three_ separate rings, which, from the calculations of Mr. Bond, an
+American astronomer, must be fluid. He is of opinion that the number
+of rings is continually changing, and that their maximum number, in
+the normal condition of the mass, does not exceed _twenty_. Mr. Bond
+likewise maintains that the power which sustains the centre of gravity
+of the _ring_ is not in the planet itself, but in its satellites; and
+the satellites, though constantly disturbing the ring, actually sustain
+it in the very act of perturbation. M. Otto Struve and Mr. Bond have
+lately studied with the great Munich telescope, at the observatory of
+Pulkowa, the _third_ ring of Saturn, which Mr. Lassell and Mr. Bond
+discovered to be _fluid_. They saw distinctly the dark interval between
+this fluid ring and the two old ones, and even measured its dimensions;
+and they perceived at its inner margin an edge feebly illuminated,
+which they thought might be the commencement of a fourth ring. These
+astronomers are of opinion, that the fluid ring is not of very recent
+formation, and that it is not subject to rapid change; and they have
+come to the extraordinary conclusion, that the inner border of the ring
+has, since the time of Huygens, been gradually approaching to the body
+of Saturn, and that _we may expect, sooner or later, perhaps in some
+dozen of years, to see the rings united with the body of the planet_.
+But this theory is by other observers pronounced untenable.
+
+
+TEMPERATURE OF THE PLANET MERCURY.
+
+Mercury being so much nearer to the Sun than the Earth, he receives,
+it is supposed, seven times more heat than the earth. Mrs. Somerville
+says: “On Mercury, the mean heat arising from the intensity of the
+sun’s rays must be above that of boiling quicksilver, and water would
+boil even at the poles.” But he may be provided with an atmosphere
+so constituted as to absorb or reflect a great portion of the
+superabundant heat; so that his inhabitants (if he have any) may enjoy
+a climate as temperate as any on our globe.
+
+
+SPECULATIONS ON VESTA AND PALLAS.
+
+The most remarkable peculiarities of these ultra-zodiacal planets,
+according to Sir John Herschel, must lie in this condition of their
+state: a man placed on one of them would spring with ease sixty feet
+high, and sustain no greater shock in his descent than he does on the
+earth from leaping a yard. On such planets, giants might exist; and
+those enormous animals which on the earth require the buoyant power of
+water to counteract their weight, might there be denizens of the land.
+But of such speculations there is no end.
+
+
+IS THE PLANET MARS INHABITED?
+
+The opponents of the doctrine of the Plurality of Worlds allow that a
+greater probability exists of Mars being inhabited than in the case of
+any other planet. His diameter is 4100 miles; and his surface exhibits
+spots of different hues,--the _seas_, according to Sir John Herschel,
+being _green_, and the land _red_. “The variety in the spots,” says
+this astronomer, “may arise from the planet not being destitute of
+atmosphere and cloud; and what adds greatly to the probability of this,
+is the appearance of brilliant white spots at its poles, which have
+been conjectured, with some probability, to be snow, as they disappear
+when they have been long exposed to the sun, and are greatest when
+emerging from the long night of their polar winter, the snow-line then
+extending to about six degrees from the pole.” “The length of the day,”
+says Sir David Brewster, “is almost exactly twenty-four hours,--the
+same as that of the earth. Continents and oceans and green savannahs
+have been observed upon Mars, and the snow of his polar regions has
+been seen to disappear with the heat of summer.” We actually see the
+clouds floating in the atmosphere of Mars, and there is the appearance
+of land and water on his disc. In a sketch of this planet, as seen in
+the pure atmosphere of Calcutta by Mr. Grant, it appears, to use his
+words, “actually as a little world,” and as the earth would appear at
+a distance, with its seas and continents of different shades. As the
+diameter of Mars is only about one half that of our earth, the weight
+of bodies will be about one half what it would be if they were placed
+upon our globe.
+
+
+DISCOVERY OF THE PLANET NEPTUNE.
+
+This noble discovery marked in a signal manner the maturity of
+astronomical science. The proof, or at least the urgent presumption,
+of the existence of such a planet, as a means of accounting (by its
+attraction) for certain small irregularities observed in the motions
+of Uranus, was afforded almost simultaneously by the independent
+researches of two geometers, Mr. Adams of Cambridge, and M. Leverrier
+of Paris, who were enabled _from theory alone_ to calculate whereabouts
+it ought to appear in the heavens, _if visible_, the places thus
+independently calculated agreeing surprisingly. _Within a single
+degree_ of the place assigned by M. Leverrier’s calculations, and by
+him communicated to Dr. Galle of the Royal Observatory at Berlin, it
+was actually found by that astronomer on the very first night after
+the receipt of that communication, on turning a telescope on the spot,
+and comparing the stars in its immediate neighbourhood with those
+previously laid down in one of the zodiacal charts. This remarkable
+verification of an indication so extraordinary took place on the 23d of
+September 1846.[20]--_Sir John Herschel’s Outlines._
+
+Neptune revolves round the sun in about 172 years, at a mean distance
+of thirty,--that of Uranus being nineteen, and that of the earth one:
+and by its discovery the solar system has been extended _one thousand
+millions of miles_ beyond its former limit.
+
+Neptune is suspected to have a ring, but the suspicion has not been
+confirmed. It has been demonstrated by the observations of Mr. Lassell,
+M. Otto Struve, and Mr. Bond, to be attended by at least one satellite.
+
+One of the most curious facts brought to light by the discovery of
+Neptune, is the failure of Bode’s law to give an approximation to its
+distance from the sun; a striking exemplification of the danger of
+trusting to the universal applicability of an empirical law. After
+standing the severe test which led to the discovery of the asteroids,
+it seemed almost contrary to the laws of probability that the discovery
+of another member of the planetary system should prove its failure as
+an universal rule.
+
+
+MAGNITUDE OF COMETS.
+
+Although Comets have a smaller mass than any other cosmical
+bodies--being, according to our present knowledge, probably not equal
+to 1/5000th part of the earth’s mass--yet they occupy the largest
+space, as their tails in several instances extend over many millions of
+miles. The cone of luminous vapour which radiates from them has been
+found in some cases (as in 1680 and 1811) equal to the length of the
+earth’s distance from the sun, forming a line that intersects both the
+orbits of Venus and Mercury. It is even probable that the vapour of
+the tails of comets mingled with our atmosphere in the years 1819 and
+1823.--_Humboldt’s Cosmos_, vol. i.
+
+
+COMETS VISIBLE IN SUNSHINE--THE GREAT COMET OF 1843.
+
+The phenomenon of the tail of a Comet being visible in bright Sunshine,
+which is recorded of the comet of 1402, occurred again in the case of
+the large comet of 1843, whose nucleus and tail were seen in North
+America on February 28th (according to the testimony of J. G. Clarke,
+of Portland, State of Maine), between one and three o’clock in the
+afternoon. The distance of the very dense nucleus from the sun’s
+light admitted of being measured with much exactness. The nucleus and
+tail (a darker space intervening) appeared like a very pure white
+cloud.--_American Journal of Science_, vol. xiv.
+
+E. C. Otté, the translator of Bohn’s edition of Humboldt’s _Cosmos_,
+at New Bedford, Massachusetts, U.S., Feb. 28th, 1843, distinctly saw
+the above comet between one and two in the afternoon. The sky at the
+time was intensely blue, and the sun shining with a dazzling brightness
+unknown in European climates.
+
+This very remarkable Comet, seen in England on the 17th of March
+1843, had a nucleus with the appearance of a planetary disc, and the
+brightness of a star of the first or second magnitude. It had a double
+tail divided by a dark line. At the Cape of Good Hope it was seen in
+full daylight, and in the immediate vicinity of the sea; but the most
+remarkable fact in its history was its near approach to the sun, its
+distance from his surface being only _one-fourteenth_ of his diameter.
+The heat to which it was exposed, therefore, was much greater than that
+which Sir Isaac Newton ascribed to the comet of 1680, namely 200 times
+that of red-hot iron. Sir John Herschel has computed that it must have
+been 24 times greater than that which was produced in the focus of
+Parker’s burning lens, 32 inches in diameter, which melts crystals of
+quartz and agate.[21]
+
+
+THE MILKY WAY UNFATHOMABLE.
+
+M. Struve of Pulkowa has compared Sir William Herschel’s opinion
+on this subject, as maintained in 1785, with that to which he was
+subsequently led; and arrives at the conclusion that, according to Sir
+W. Herschel himself, the visible extent of the Milky Way increases with
+the penetrating power of the telescopes employed; that it is impossible
+to discover by his instruments the termination of the Milky Way (as an
+independent cluster of stars); and that even his gigantic telescope of
+forty feet focal length does not enable him to extend our knowledge
+of the Milky Way, which is incapable of being sounded. Sir William
+Herschel’s _Theory of the Milky Way_ was as follows: He considered
+our solar system, and all the stars which we can see with the eye, as
+placed within, and constituting a part of, the nebula of the Milky Way,
+a congeries of many millions of stars, so that the projection of these
+stars must form a luminous track on the concavity of the sky; and by
+estimating or counting the number of stars in different directions, he
+was able to form a rude judgment of the probable form of the nebula,
+and of the probable position of the solar system within it.
+
+This remarkable belt has maintained from the earliest ages the same
+relative situation among the stars; and, when examined through powerful
+telescopes, is found (wonderful to relate!) _to consist entirely of
+stars scattered by millions_, like glittering dust, on the black ground
+of the general heavens.
+
+
+DISTANCES OF NEBULÆ.
+
+These are truly astounding. Sir William Herschel estimated the distance
+of the annular nebula between Beta and Gamma Lyræ to be from our system
+950 times that of Sirius; and a globular cluster about 5½° south-east
+of Beta Sir William computed to be one thousand three hundred billions
+of miles from our system. Again, in Scutum Sobieski is one nebula in
+the shape of a horseshoe; but which, when viewed with high magnifying
+power, presents a different appearance. Sir William Herschel estimated
+this nebula to be 900 times farther from us than Sirius. In some parts
+of its vicinity he observed 588 stars in his telescope at one time;
+and he counted 258,000 in a space 10° long and 2½° wide. There is a
+globular cluster between the mouths of Pegasus and Equuleus, which
+Sir William Herschel estimated to be 243 times farther from us than
+Sirius. Caroline Herschel discovered in the right foot of Andromeda
+a nebula of enormous dimensions, placed at an inconceivable distance
+from us: it consists probably of myriads of solar systems, which, taken
+together, are but a point in the universe. The nebula about 10° west of
+the principal star in Triangulum is supposed by Sir William Herschel
+to be 344 times the distance of Sirius from the earth, which would be
+the immense sum of nearly seventeen thousand billions of miles from our
+planet.
+
+
+INFINITE SPACE.
+
+After the straining mind has exhausted all its resources in attempting
+to fathom the distance of the smallest telescopic star, or the faintest
+nebula, it has reached only the visible confines of the sidereal
+creation. The universe of stars is but an atom in the universe of
+space; above it, and beneath it, and around it, there is still infinity.
+
+
+ORIGIN OF OUR PLANETARY SYSTEM. THE NEBULAR HYPOTHESIS.[22]
+
+The commencement of our Planetary System, including the sun, must,
+according to Kant and Laplace, be regarded as an immense nebulous mass
+filling the portion of space which is now occupied by our system far
+beyond the limits of Neptune, our most distant planet. Even now we
+perhaps see similar masses in the distant regions of the firmament, as
+patches of nebulæ, and nebulous stars; within our system also, comets,
+the zodiacal light, the corona of the sun during a total eclipse,
+exhibit resemblances of a nebulous substance, which is so thin that the
+light of the stars passes through it unenfeebled and unrefracted. If we
+calculate the density of the mass of our planetary system, according
+to the above assumption, for the time when it was a nebulous sphere
+which reached to the path of the outmost planet, we should find that
+it would require several cubic miles of such matter to weigh a single
+grain.--_Professor Helmholtz._
+
+A quarter of a century ago, Sir John Herschel expressed his opinion
+that those nebulæ which were not resolved into individual stars by the
+highest powers then used, might be hereafter completely resolved by a
+further increase of optical power:
+
+  In fact, this probability has almost been converted into a
+  certainty by the magnificent reflecting telescope constructed by
+  Lord Rosse, of 6 feet in aperture, which has resolved, or rendered
+  resolvable, multitudes of nebulæ which had resisted all inferior
+  powers. The sublimity of the spectacle afforded by that instrument
+  of some of the larger globular and other clusters is declared by
+  all who have witnessed it to be such as no words can express.[23]
+
+  Although, therefore, nebulæ do exist, which even in this powerful
+  telescope appear as nebulæ, without any sign of resolution, it may
+  very reasonably be doubted whether there be really any essential
+  physical distinction between nebulæ and clusters of stars, at least
+  in the nature of the matter of which they consist; and whether the
+  distinction between such nebulæ as are easily resolved, barely
+  resolvable with excellent telescopes, and altogether irresolvable
+  with the best, be any thing else than one of degree, arising merely
+  from the excessive minuteness and multitude of the stars of which
+  the latter, as compared with the former, consist.--_Outlines of
+  Astronomy_, 5th edit. 1858.
+
+It should be added, that Sir John Herschel considers the “nebular
+hypothesis” and the above theory of sidereal aggregation to stand quite
+independent of each other.
+
+
+ORIGIN OF HEAT IN OUR SYSTEM.
+
+Professor Helmholtz, assuming that at the commencement the density of
+the nebulous matter was a vanishing quantity, as compared with the
+present density of the sun and planets, calculates how much work has
+been performed by the condensation; how much of this work still exists
+in the form of mechanical force, as attraction of the planets towards
+the sun, and as _vis viva_ of their motion; and finds by this how much
+of the force has been converted into heat.
+
+  The result of this calculation is, that only about the 45th part
+  of the original mechanical force remains as such, and that the
+  remainder, converted into heat, would be sufficient to raise a
+  mass of water equal to the sun and planets taken together, not
+  less than 28,000,000 of degrees of the centigrade scale. For the
+  sake of comparison, Professor Helmholtz mentions that the highest
+  temperature which we can produce by the oxy-hydrogen blowpipe,
+  which is sufficient to vaporise even platina, and which but few
+  bodies can endure, is estimated at about 2000 degrees. Of the
+  action of a temperature of 28,000,000 of such degrees we can form
+  no notion. If the mass of our entire system were of pure coal, by
+  the combustion of the whole of it only the 350th part of the above
+  quantity would be generated.
+
+  The store of force at present possessed by our system is equivalent
+  to immense quantities of heat. If our earth were by a sudden shock
+  brought to rest in her orbit--which is not to be feared in the
+  existing arrangement of our system--by such a shock a quantity of
+  heat would be generated equal to that produced by the combustion of
+  fourteen such earths of solid coal. Making the most unfavourable
+  assumption as to its capacity for heat, that is, placing it equal
+  to that of water, the mass of the earth would thereby be heated
+  11,200°; it would therefore be quite fused, and for the most part
+  reduced to vapour. If, then, the earth, after having been thus
+  brought to rest, should fall into the sun, which of course would be
+  the case, the quantity of heat developed by the shock would be 400
+  times greater.
+
+
+AN ASTRONOMER’S DREAM VERIFIED.
+
+The most fertile region in astronomical discovery during the last
+quarter of a century has been the planetary members of the solar
+system. In 1833, Sir John Herschel enumerated ten planets as visible
+from the earth, either by the unaided eye or by the telescope; the
+number is now increased more than fivefold. With the exception of
+Neptune, the discovery of new planets is confined to the class called
+Asteroids. These all revolve in elliptic orbits between those of
+Jupiter and Mars. Zitius of Wittemberg discovered an empirical law,
+which seemed to govern the distances of the planets from the sun; but
+there was a remarkable interruption in the law, according to which a
+planet ought to have been placed between Mars and Jupiter. Professor
+Bode of Berlin directed the attention of astronomers to the possibility
+of such a planet existing; and in seven years’ observations from the
+commencement of the present century, not one but four planets were
+found, differing widely from one another in the elements of their
+orbits, but agreeing very nearly at their mean distances from the sun
+with that of the supposed planet. This curious coincidence of the mean
+distances of these four asteroids with the planet according to Bode’s
+law, as it is generally called, led to the conjecture that these four
+planets were but fragments of the missing planet, blown to atoms by
+some internal explosion, and that many more fragments might exist, and
+be possibly discovered by diligent search.
+
+Concerning this apparently wild hypothesis, Sir John Herschel offered
+the following remarkable apology: “This may serve as a specimen of the
+dreams in which astronomers, like other speculators, occasionally and
+harmlessly indulge.”
+
+The dream, wild as it appeared, has been realised now. Sir John, in the
+fifth edition of his _Outlines of Astronomy_, published in 1858, tells
+us:
+
+  Whatever may be thought of such a speculation as a physical
+  hypothesis, this conclusion has been verified to a considerable
+  extent as a matter of fact by subsequent discovery, the result
+  of a careful and minute examination and mapping down of the
+  smaller stars in and near the zodiac, undertaken with that express
+  object. Zodiacal charts of this kind, the product of the zeal and
+  industry of many astronomers, have been constructed, in which
+  every star down to the ninth, tenth, or even lower magnitudes, is
+  inserted; and these stars being compared with the actual stars of
+  the heavens, the intrusion of any stranger within their limits
+  cannot fail to be noticed when the comparison is systematically
+  conducted. The discovery of Astræa and Hebe by Professor Hencke,
+  in 1845 and 1847, revived the flagging spirit of inquiry in this
+  direction; with what success, the list of fifty-two asteroids,
+  with their names and the dates of their discovery, will best show.
+  The labours of our indefatigable countryman, Mr. Hind, have been
+  rewarded by the discovery of no less than eight of them.
+
+
+FIRE-BALLS AND SHOOTING STARS.
+
+Humboldt relates, that a friend at Popayan, at an elevation of 5583
+feet above the sea-level, at noon, when the sun was shining brightly
+in a cloudless sky, saw his room lighted up by a fire-ball: he had his
+back towards the window at the time, and on turning round, perceived
+that great part of the path traversed by the fire-ball was still
+illuminated by the brightest radiance. The Germans call these phenomena
+_star-snuff_, from the vulgar notion that the lights in the firmament
+undergo a process of snuffing, or cleaning. Other nations call it _a
+shot or fall of stars_, and the English _star-shoot_. Certain tribes
+of the Orinoco term the pearly drops of dew which cover the beautiful
+leaves of the heliconia _star-spit_. In the Lithuanian mythology, the
+nature and signification of falling stars are embodied under nobler and
+more graceful symbols. The Parcæ, _Werpeja_, weave in heaven for the
+new-born child its thread of fate, attaching each separate thread to
+a star. When death approaches the person, the thread is rent, and the
+star wanes and sinks to the earth.--_Jacob Grimm._
+
+
+THEORY AND EXPERIENCE.
+
+In the perpetual vicissitude of theoretical views, says the author of
+_Giordano Bruno_, “most men see nothing in philosophy but a succession
+of passing meteors; whilst even the grander forms in which she has
+revealed herself share the fate of comets,--bodies that do not rank in
+popular opinion amongst the external and permanent works of nature, but
+are regarded as mere fugitive apparitions of igneous vapour.”
+
+
+METEORITES FROM THE MOON.
+
+The hypothesis of the selenic origin of meteoric stones depends upon
+a number of conditions, the accidental coincidence of which could
+alone convert a possible to an actual fact. The view of the original
+existence of small planetary masses in space is simpler, and at
+the same time more analogous with those entertained concerning the
+formation of other portions of the solar system.
+
+  Diogenes Laertius thought aerolites came from the sun; but Pliny
+  derides this theory. The fall of aerolites in bright sunshine, and
+  when the moon’s disc was invisible, probably led to the idea of
+  sun-stones. Moreover Anaxagoras regarded the sun as “a molten fiery
+  mass;” and Euripides, in Phaëton, terms the sun “a golden mass,”
+  that is to say, a fire-coloured, brightly-shining matter, but not
+  leading to the inference that aerolites are golden sun-stones.
+  The Greek philosophers had four hypotheses as to their origin:
+  telluric, from ascending exhalations; masses of stone raised by
+  hurricanes; a solar origin; and lastly, an origin in the regions of
+  space, as heavenly bodies which had long remained invisible: the
+  last opinion entirely according with that of the present day.
+
+  Chladni states that an Italian physicist, Paolo Maria Terzago,
+  on the occasion of the fall of an aerolite at Milan, in 1660, by
+  which a Franciscan monk was killed, was the first who surmised that
+  aerolites were of selenic origin. Without any previous knowledge
+  of this conjecture, Olbers was led, in 1795 (after the celebrated
+  fall at Siena, June 16th, 1794), to investigate the amount of the
+  initial tangential force that would be required to bring to the
+  earth masses projected from the moon. Olbers, Brandes, and Chaldni
+  thought that “the velocity of 16 to 32 miles, with which fire-balls
+  and shooting-stars entered our atmosphere,” furnished a refutation
+  to the view of their selenic origin. According to Olbers, it would
+  require to reach the earth, setting aside the resistance of the
+  air, an initial velocity of 8292 feet in the second; according to
+  Laplace, 7862; to Biot, 8282; and to Poisson, 7595. Laplace states
+  that this velocity is only five or six times as great as that of
+  a cannon-ball; but Olbers has shown that “with such an initial
+  velocity as 7500 or 8000 feet in a second, meteoric stones would
+  arrive at the surface of our earth with a velocity of only 35,000
+  feet.” But the measured velocity of meteoric stones averages
+  upwards of 114,000 feet to a second; consequently the original
+  velocity of projection from the moon must be almost 110,000 feet,
+  and therefore 14 times greater than Laplace asserted. It must,
+  however, be recollected, that the opinion then so prevalent, of the
+  existence of active volcanoes in the moon, where air and water are
+  absent, has since been abandoned.
+
+  Laplace elsewhere states, that in all probability aerolites “come
+  from the depths of space;” yet he in another passage inclines to
+  the hypothesis of their lunar origin, always, however, assuming
+  that the stones projected from the moon “become satellites of our
+  earth, describing around it more or less eccentric orbits, and thus
+  not reaching its atmosphere until several or even many revolutions
+  have been accomplished.”
+
+  In Syria there is a popular belief that aerolites chiefly fall
+  on clear moonlight nights. The ancients (Pliny tells us) looked
+  for their fall during lunar eclipses.--_Abridged from Humboldt’s
+  Cosmos_, vol. i. (Bohn’s edition).
+
+Dr. Laurence Smith, U.S., accepts the “lunar theory,” and considers
+meteorites to be masses thrown off from the moon, the attractive power
+of which is but one-sixth that of the earth; so that bodies thrown from
+the surface of the moon experience but one sixth the retarding force
+they would have when thrown from the earth’s surface.
+
+  Look again (says Dr. Smith) at the constitution of the meteorite,
+  made up principally of _pure_ iron. It came evidently from some
+  place where there is little or no oxygen. Now the moon has no
+  atmosphere, and no water on its surface. There is no oxygen there.
+  Hurled from the moon, these bodies,--these masses of almost pure
+  iron,--would flame in the sun like polished steel, and on reaching
+  our atmosphere would burn in its oxygen until a black oxide cooled
+  it; and this we find to be the case with all meteorites,--the
+  black colour is only an external covering.
+
+Sir Humphry Davy, from facts contained in his researches on flame,
+in 1817, conceives that the light of meteors depends, not upon the
+ignition of inflammable gases, but upon that of solid bodies; that such
+is their velocity of motion, as to excite sufficient heat for their
+ignition by the compression even of rare air; and that the phenomena of
+falling stars may be explained by regarding them as small incombustible
+bodies moving round the earth in very eccentric orbits, and becoming
+ignited only when they pass with immense rapidity through the upper
+regions of the atmosphere; whilst those meteors which throw down stony
+bodies are, similarly circumstanced, combustible masses.
+
+Masses of iron and nickel, having all the appearance of aerolites or
+meteoric stones, have been discovered in Siberia, at a depth of ten
+metres below the surface of the earth. From the fact, however, that no
+meteoric stones are found in the secondary and tertiary formations, it
+would seem to follow that the phenomena of falling stones did not take
+place till the earth assumed its present conditions.
+
+
+VAST SHOWER OF METEORS.
+
+The most magnificent Shower of Meteors that has ever been known was
+that which fell during the night of November 12th, 1833, commencing
+at nine o’clock in the evening, and continuing till the morning sun
+concealed the meteors from view. This shower extended from Canada to
+the northern boundary of South America, and over a tract of nearly 3000
+miles in width.
+
+
+IMMENSE METEORITE.
+
+Mrs. Somerville mentions a Meteorite which passed within twenty-five
+miles of our planet, and was estimated to weigh 600,000 tons, and to
+move with a velocity of twenty miles in a second. Only a small fragment
+of this immense mass reached the earth. Four instances are recorded
+of persons being killed by their fall. A block of stone fell at Ægos
+Potamos, B.C. 465, as large as two millstones; another at Narni, in
+921, projected like a rock four feet above the surface of the river,
+in which it was seen to fall. The Emperor Jehangire had a sword forged
+from a mass of meteoric iron, which fell in 1620 at Jahlinder in the
+Punjab. Sixteen instances of the fall of stones in the British Isles
+are well authenticated to have occurred since 1620, one of them in
+London. It is very remarkable that no new chemical element has been
+detected in any of the numerous meteorites which have been analysed.
+
+
+NO FOSSIL METEORIC STONES.
+
+It is (says Olbers) a remarkable but hitherto unregarded fact, that
+while shells are found in secondary and tertiary formations, no Fossil
+Meteoric Stones have as yet been discovered. May we conclude from this
+circumstance, that previous to the present and last modification of the
+earth’s surface no meteoric stones fell on it, though at the present
+time it appears probable, from the researches of Schreibers, that 700
+fall annually?[24]
+
+
+THE END OF OUR SYSTEM.
+
+While all the phenomena in the heavens indicate a law of progressive
+creation, in which revolving matter is distributed into suns and
+planets, there are indications in our own system that a period has been
+assigned for its duration, which, sooner or later, it must reach. The
+medium which fills universal space, whether it be a luminiferous ether,
+or arise from the indefinite expansion of planetary atmospheres, must
+retard the bodies which move in it, even were it 360,000 millions of
+times more rare than atmospheric air; and, with its time of revolution
+gradually shortening, the satellite must return to its planet, the
+planet to its sun, and the sun to its primeval nebula. The fate of our
+system, thus deduced from mechanical laws, must be the fate of all
+others. Motion cannot be perpetuated in a resisting medium; and where
+there exist disturbing forces, there must be primarily derangement,
+and ultimately ruin. From the great central mass, heat may again be
+summoned to exhale nebulous matter; chemical forces may again produce
+motion, and motion may again generate systems; but, as in the recurring
+catastrophes which have desolated our earth, the great First Cause must
+preside at the dawn of each cosmical cycle; and, as in the animal races
+which were successively reproduced, new celestial creations of a nobler
+form of beauty and of a higher form of permanence may yet appear in
+the sidereal universe. “Behold, I create new heavens and a new earth,
+and the former shall not be remembered.” “The new heavens and the
+new earth shall remain before me.” “Let us look, then, according to
+this promise, for the new heavens and the new earth, wherein dwelleth
+righteousness.”--_North-British Review_, No. 3.
+
+
+BENEFITS OF GLASS TO MAN.
+
+Cuvier eloquently says: “It could not be expected that those Phœnician
+sailors who saw the sand of the shores of Bætica transformed by fire
+into a transparent Glass, should have at once foreseen that this new
+substance would prolong the pleasures of sight to the old; that it
+would one day assist the astronomer in penetrating the depths of the
+heavens, and in numbering the stars of the Milky Way; that it would
+lay open to the naturalist a miniature world, as populous, as rich in
+wonders as that which alone seemed to have been granted to his senses
+and his contemplation: in fine, that the most simple and direct use
+of it would enable the inhabitants of the coast of the Baltic Sea to
+build palaces more magnificent than those of Tyre and Memphis, and to
+cultivate, almost under the polar circle, the most delicious fruit of
+the torrid zone.”
+
+
+THE GALILEAN TELESCOPE.
+
+Galileo appears to be justly entitled to the honour of having invented
+that form of Telescope which still bears his name; while we must accord
+to John Lippershey, the spectacle-maker of Middleburg, the honour of
+having previously invented the astronomical telescope. The interest
+excited at Venice by Galileo’s invention amounted almost to frenzy.
+On ascending the tower of St. Mark, that he might use one of his
+telescopes without molestation, Galileo was recognised by a crowd in
+the street, who took possession of the wondrous tube, and detained the
+impatient philosopher for several hours, till they had successively
+witnessed its effects. These instruments were soon manufactured in
+great numbers; but were purchased merely as philosophical toys, and
+were carried by travellers into every corner of Europe.
+
+
+WHAT GALILEO FIRST SAW WITH HIS TELESCOPE.
+
+The moon displayed to him her mountain-ranges and her glens, her
+continents and her highlands, now lying in darkness, now brilliant with
+sunshine, and undergoing all those variations of light and shadow which
+the surface of our own globe presents to the alpine traveller or to the
+aeronaut. The four satellites of Jupiter illuminating their planet, and
+suffering eclipses in his shadow, like our own moon; the spots on the
+sun’s disc, proving his rotation round his axis in twenty-five days;
+the crescent phases of Venus, and the triple form or the imperfectly
+developed ring of Saturn,--were the other discoveries in the solar
+system which rewarded the diligence of Galileo. In the starry heavens,
+too, thousands of new worlds were discovered by his telescope; and the
+Pleiades alone, which to the unassisted eye exhibit only _seven_ stars,
+displayed to Galileo no fewer than _forty_.--_North-British Review_,
+No. 3.
+
+  The first telescope “the starry Galileo” constructed with a leaden
+  tube a few inches long, with a spectacle-glass, one convex and one
+  concave, at each of its extremities. It magnified three times.
+  Telescopes were made in London in February 1610, a year after
+  Galileo had completed his own (Rigaud, _On Harriot’s Papers_,
+  1833). They were at first called _cylinders_. The telescopes which
+  Galileo constructed, and others of which he made use for observing
+  Jupiter’s satellites, the phases of Venus, and the solar spots,
+  possessed the gradually-increasing powers of magnifying four,
+  seven, and thirty-two linear diameters; but they never had a higher
+  power.--Arago, in the _Annuaire_ for 1842.
+
+  Clock-work is now applied to the equatorial telescope, so as to
+  allow the observer to follow the course of any star, comet, or
+  planet he may wish to observe continuously, without using his hands
+  for the mechanical motion of the instrument.
+
+
+ANTIQUITY OF TELESCOPES.
+
+Long tubes were certainly employed by Arabian astronomers, and very
+probably also by the Greeks and Romans; the exactness of their
+observations being in some degree attributable to their causing the
+object to be seen through diopters or slits. Abul Hassan speaks very
+distinctly of tubes, to the extremities of which ocular and object
+diopters were attached; and instruments so constructed were used in
+the observatory founded by Hulagu at Meragha. If stars be more easily
+discovered during twilight by means of tubes, and if a star be sooner
+revealed to the naked eye through a tube than without it, the reason
+lies, as Arago has truly observed, in the circumstance that the tube
+conceals a great portion of the disturbing light diffused in the
+atmospheric strata between the star and the eye applied to the tube.
+In like manner, the tube prevents the lateral impression of the faint
+light which the particles of air receive at night from all the other
+stars in the firmament. The intensity of the image and the size of the
+star are apparently augmented.--_Humboldt’s Cosmos_, vol. iii. p. 53.
+
+
+NEWTON’S FIRST REFLECTING TELESCOPE.
+
+The year 1668 may be regarded as the date of the invention of
+Newton’s Reflecting Telescope. Five years previously, James Gregory
+had described the manner of constructing a reflecting telescope with
+two concave specula; but Newton perceived the disadvantages to be so
+great, that, according to his statement, he “found it necessary, before
+attempting any thing in the practice, to alter the design, and place
+the eye-glass at the side of the tube rather than at the middle.” On
+this improved principle Newton constructed his telescope, which was
+examined by Charles II.; it was presented to the Royal Society near the
+end of 1671, and is carefully preserved by that distinguished body,
+with the inscription:
+
+  “THE FIRST REFLECTING TELESCOPE; INVENTED BY SIR ISAAC NEWTON, AND
+  MADE WITH HIS OWN HANDS.”
+
+Sir David Brewster describes this telescope as consisting of a concave
+metallic speculum, the radius of curvature of which was 12-2/3 or
+13 inches, so that “it collected the sun’s rays at the distance of
+6-1/3 inches.” The rays reflected by the speculum were received upon
+a plane metallic speculum inclined 45° to the axis of the tube, so as
+to reflect them to the side of the tube in which there was an aperture
+to receive a small tube with a plano-convex eye-glass whose radius
+was one-twelfth of an inch, by means of which the image formed by
+the speculum was magnified 38 times. Such was the first reflecting
+telescope applied to the heavens; but Sir David Brewster describes
+this instrument as small and ill-made; and fifty years elapsed before
+telescopes of the Newtonian form became useful in astronomy.
+
+
+SIR WILLIAM HERSCHEL’S GREAT TELESCOPE AT SLOUGH.
+
+The plan of this Telescope was intimated by Herschel, through Sir
+Joseph Banks, to George III., who offered to defray the whole expense
+of it; a noble act of liberality, which has never been imitated by
+any other British sovereign. Towards the close of 1785, accordingly,
+Herschel began to construct his reflecting telescope, _forty feet in
+length_, and having a speculum _fully four feet in diameter_. The
+thickness of the speculum, which was uniform in every part, was 3½
+inches, and its weight nearly 2118 pounds; the metal being composed of
+32 copper, and 10·7 of tin: it was the third speculum cast, the two
+previous attempts having failed. The speculum, when not in use, was
+preserved from damp by a tin cover, fitted upon a rim of close-grained
+cloth. The tube of the telescope was 39 ft. 4 in. long, and its width 4
+ft. 10 in.; it was made of iron, and was 3000 lbs. lighter than if it
+had been made of wood. The observer was seated in a suspended movable
+seat at the mouth of the tube, and viewed the image of the object with
+a magnifying lens or eye-piece. The focus of the speculum, or place of
+the image, was within four inches of the lower side of the mouth of the
+tube, and came forward into the air, so that there was space for part
+of the head above the eye, to prevent it from intercepting many of the
+rays going from the object to the mirror. The eye-piece moved in a tube
+carried by a slider directed to the centre of the speculum, and fixed
+on an adjustible foundation at the mouth of the tube. It was completed
+on the 27th August 1789; and _the very first moment_ it was directed to
+the heavens, a new body was added to the solar system, namely, Saturn
+and six of its satellites; and in less than a month after, the seventh
+satellite of Saturn, “an object,” says Sir John Herschel, “of a far
+higher order of difficulty.”--_Abridged from the North-British Review_,
+No. 3.
+
+  This magnificent instrument stood on the lawn in the rear of Sir
+  William Herschel’s house at Slough; and some of our readers, like
+  ourselves, may remember its extraordinary aspect when seen from
+  the Bath coach-road, and the road to Windsor. The difficulty of
+  managing so large an instrument--requiring as it did two assistants
+  in addition to the observer himself and the person employed to note
+  the time--prevented its being much used. Sir John Herschel, in a
+  letter to Mr. Weld, states the entire cost of its construction,
+  4000_l._, was defrayed by George III. In 1839, the woodwork of
+  the telescope being decayed, Sir John Herschel had it cleared
+  away; and piers were erected, on which the tube was placed, _that_
+  being of iron, and so well preserved that, although not more than
+  one-twentieth of an inch thick, when in the horizontal position
+  it contained within all Sir John’s family; and next the two
+  reflectors, the polishing apparatus, and portions of the machinery,
+  to the amount of a great many tons. Sir John attributes this great
+  strength and resistance to the internal structure of the tube, very
+  similar to that patented under the name of corrugated iron-roping.
+  Sir John Herschel also thinks that system of triangular arrangement
+  of the woodwork was upon the principle to which “diagonal bracing”
+  owes its strength.
+
+
+THE EARL OF ROSSE’S GREAT REFLECTING TELESCOPE.
+
+Sir David Brewster has remarked, that “the long interval of half
+a century seems to be the period of hybernation during which the
+telescopic mind rests from its labours in order to acquire strength for
+some great achievement. Fifty years elapsed between the dwarf telescope
+of Newton and the large instruments of Hadley; other fifty years rolled
+on before Sir William Herschel constructed his magnificent telescope;
+and fifty years more passed away before the Earl of Rosse produced
+that colossal instrument which has already achieved such brilliant
+discoveries.”[25]
+
+In the improvement of the Reflecting Telescope, the first object
+has always been to increase the magnifying power and light by the
+construction of as large a mirror as possible; and to this point Lord
+Rosse’s attention was directed as early as 1828, the field of operation
+being at his lordship’s seat, Birr Castle at Parsonstown, about fifty
+miles west of Dublin. For this high branch of scientific inquiry Lord
+Rosse was well fitted by a rare combination of “talent to devise,
+patience to bear disappointment, perseverance, profound mathematical
+knowledge, mechanical skill, and uninterrupted leisure from other
+pursuits;”[26] all these, however, would not have been sufficient, had
+not a great command of money been added; the gigantic telescope we are
+about to describe having cost certainly not less than twelve thousand
+pounds.
+
+  Lord Rosse ground and polished specula fifteen inches, two feet,
+  and three feet in diameter before he commenced the colossal
+  instrument. It is impossible here to detail the admirable
+  contrivances and processes by which he prepared himself for this
+  great work. He first ascertained the most useful combination of
+  metals for specula, both in whiteness, porosity, and hardness,
+  to be copper and tin. Of this compound the reflector was cast in
+  pieces, which were fixed on a bed of zinc and copper,--a species
+  of brass which expanded in the same degree by heat as the pieces
+  of the speculum themselves. They were ground as one body to a true
+  surface, and then polished by machinery moved by a steam-engine.
+  The peculiarities of this mechanism were entirely Lord Rosse’s
+  invention, and the result of close calculation and observation:
+  they were chiefly, placing the speculum with the face upward,
+  regulating the temperature by having it immersed in water, usually
+  at 55° Fahr., and regulating the pressure and velocity. This was
+  found to work a perfect spherical figure in large surfaces with
+  a degree of precision unattainable by the hand; the polisher, by
+  working above and upon the face of the speculum, being enabled
+  to examine the operation as it proceeded without removing the
+  speculum, which, when a ton weight, is no easy matter.
+
+  The contrivance for doing this is very beautiful. The machine is
+  placed in a room at the bottom of a high tower, in the successive
+  floors of which trap-doors can be opened. A mast is elevated on the
+  top of the tower, so that its summit is about ninety feet _above_
+  the speculum. A dial-plate is attached to the top of the mast, and
+  a small plane speculum and eye-piece, with proper adjustments,
+  are so placed that the combination becomes a Newtonian telescope,
+  and the dial-plate the object. The last and most important part
+  of the process of working the speculum, is to give it a _true
+  parabolic figure_, that is, such a figure that each portion of it
+  should reflect the incident ray to the same focus. Lord Rosse’s
+  operations for this purpose consist--1st, of a stroke of the first
+  eccentric, which carries the polisher along _one-third_ of the
+  diameter of the speculum; 2d, a transverse stroke twenty-one times
+  slower, and equal to 0·27 of the same diameter, measured on the
+  edge of the tank, or 1·7 beyond the centre of the polisher; 3d, a
+  rotation of the speculum performed in the same time as thirty-seven
+  of the first strokes; and 4th, a rotation of the polisher in the
+  same direction about sixteen times slower. If these rules are
+  attended to, the machine will give the true parabolic figure to the
+  speculum, whether it be _six inches_ or _three feet in diameter_.
+  In the three-feet speculum, the figure is so true with the whole
+  aperture, that it is thrown out of focus by a motion of less
+  than the _thirtieth of an inch_, “and even with a single lens of
+  one-eighth of an inch focus, giving a power of 2592, the dots on a
+  watch-dial are still in some degree defined.”
+
+Thus was executed the three-feet speculum for the twenty-six-feet
+telescope placed upon the lawn at Parsonstown, which, in 1840, showed
+with powers up to 1000 and even 1600; and which resolved nebulæ into
+stars, and destroyed that symmetry of form in globular nebulæ upon
+which was founded the hypothesis of the gradual condensation of
+nebulous matter into suns and planets.[27]
+
+Scarcely was this instrument out of Lord Rosse’s hands, when he
+resolved to attempt by the same processes to construct another
+reflector, with a speculum _six feet_ in diameter and _fifty feet
+long_! and this magnificent instrument was completed early in 1845.
+The focal length of the speculum is fifty-four feet. It weighs four
+tons, and, with its supports, is seven times as heavy as the four-feet
+speculum of Sir William Herschel. The speculum is placed in one of
+the sides of a cubical wooden box, about eight feet wide, and to the
+opposite end of this box is fastened the tube, which is made of deal
+staves an inch thick, hooped with iron clamp-rings, like a huge cask.
+It carries at its upper end, and in the axis of the tube, a small oval
+speculum, six inches in its lesser diameter.
+
+The tube is about 50 feet long and 8 feet in diameter in the middle,
+and furnished with diaphragms 6½ feet in aperture. The late Dean of Ely
+walked through the tube with an umbrella up.
+
+The telescope is established between two lofty castellated piers 60
+feet high, and is raised to different altitudes by a strong chain-cable
+attached to the top of the tube. This cable passes over a pulley on
+a frame down to a windlass on the ground, which is wrought by two
+assistants. To the frame are attached chain-guys fastened to the
+counterweights; and the telescope is balanced by these counterweights
+suspended by chains, which are fixed to the sides of the tube and pass
+over large iron pulleys. The immense mass of matter weighs about twelve
+tons.
+
+On the eastern pier is a strong semicircle of cast-iron, with which the
+telescope is connected by a racked bar, with friction-rollers attached
+to the tube by wheelwork, so that by means of a handle near the
+eye-piece, the observer can move the telescope along the bar on either
+side of the meridian, to the distance of an hour for an equatorial star.
+
+On the western pier are stairs and galleries. The observing gallery is
+moved along a railway by means of wheels and a winch; and the mechanism
+for raising the galleries to various altitudes is very ingenious.
+Sometimes the galleries, filled with observers, are suspended midway
+between the two piers, over a chasm sixty feet deep.
+
+An excellent description of this immense Telescope at Birr Castle will
+be found in Mr. Weld’s volume of _Vacation Rambles_.
+
+Sir David Brewster thus eloquently sketches the powers of the telescope
+at the close of his able description of the instrument, which we have
+in part quoted from his _Life of Sir Isaac Newton_.
+
+  We have, in the mornings, walked again and again, and ever with
+  new delight, along its mystic tube, and at midnight, with its
+  distinguished architect, pondered over the marvellous sights which
+  it dis-closes,--the satellites and belts and rings of Saturn,--the
+  old and new ring, which is advancing with its crest of waters to
+  the body of the planet,--the rocks, and mountains, and valleys, and
+  extinct volcanoes of the moon,--the crescent of Venus, with its
+  mountainous outline,--the systems of double and triple stars,--the
+  nebulæ and starry clusters of every variety of shape,--and those
+  spiral nebular formations which baffle human comprehension, and
+  constitute the greatest achievement in modern discovery.
+
+The Astronomer Royal, Mr. Airy, alludes to the impression made by
+the enormous light of the telescope,--partly by the modifications
+produced in the appearance of nebulæ already figured, partly by the
+great number of stars seen at a distance from the Milky Way, and
+partly from the prodigious brilliancy of Saturn. The account given by
+another astronomer of the appearance of Jupiter was that it resembled a
+coach-lamp in the telescope; and this well expresses the blaze of light
+which is seen in the instrument.
+
+The Rev. Dr. Scoresby thus records the results of his visits:
+
+  The range opened to us by the great telescope at Birr Castle is
+  best, perhaps, apprehended by the now usual measurement--not of
+  distances in miles, or millions of miles, or diameters of the
+  earth’s orbit, but--of the progress of light in free space. The
+  determination within, no doubt, a small proportion of error of
+  the parallax of a considerable number of the fixed stars yields,
+  according to Mr. Peters, a space betwixt us and the fixed stars of
+  the smallest magnitude, the sixth, ordinarily visible to the naked
+  eye, of 130 years in the flight of light. This information enables
+  us, on the principles of _sounding the heavens_, suggested by Sir
+  W. Herschel, with the photometrical researches on the stars of Dr.
+  Wollaston and others, to carry the estimation of distances, and
+  that by no means on vague assumption, to the limits of space opened
+  out by the most effective telescopes. And from the guidance thus
+  afforded us as to the comparative power of the six feet speculum
+  in the penetration of space as already elucidated, we might fairly
+  assume the fact, that if any other telescope now in use could
+  follow the sun if removed to the remotest visible position, or
+  till its light would require 10,000 years to reach us, the grand
+  instrument at Parsonstown would follow it so far that from 20,000
+  to 25,000 years would be spent in the transmission of its light to
+  the earth. But in the cases of clusters of stars, and of nebulæ
+  exhibiting a mere speck of misty luminosity, from the combined
+  light of perhaps hundreds of thousands of suns, the _penetration_
+  into space, compared with the results of ordinary vision, must
+  be enormous; so that it would not be difficult to show the
+  _probability_ that a million of years, in flight of light, would
+  be requisite, in regard to the most distant, to trace the enormous
+  interval.
+
+
+GIGANTIC TELESCOPES PROPOSED.
+
+Hooke is said to have proposed the use of Telescopes having a length of
+upwards of 10,000 feet (or nearly two miles), in order to see animals
+in the moon! an extravagant expectation which Auzout considered it
+necessary to refute. The Capuchin monk Schyrle von Rheita, who was well
+versed in optics, had already spoken of the speedy practicability of
+constructing telescopes that should magnify 4000 times, by means of
+which the lunar mountains might be accurately laid down.
+
+Optical instruments of such enormous focal lengths remind us of the
+Arabian contrivances of measurement: quadrants with a radius of about
+190 feet, upon whose graduated limb the image of the sun was received
+as in the gnomon, through a small round aperture. Such a quadrant was
+erected at Samarcand, probably constructed after the model of the older
+sextants of Alchokandi, which were about sixty feet in height.
+
+
+LATE INVENTION OF OPTICAL INSTRUMENTS.
+
+A writer in the _North-British Review_, No. 50, considers it strange
+that a variety of facts which must have presented themselves to the
+most careless observer should not have led to the earlier construction
+of Optical Instruments. The ancients, doubtless, must have formed
+metallic articles with concave surfaces, in which the observer could
+not fail to see himself magnified; and if the radius of the concavity
+exceeded twelve inches, twice the focal distance of his eye, he had in
+his hands an extempore reflecting telescope of the Newtonian form, in
+which the concave metal was the speculum, and his eye the eye-glass,
+and which would magnify and bring near him the image of objects nearly
+behind him. Through the spherical drops of water suspended before his
+eye, an attentive observer might have seen magnified some minute body
+placed accidentally in its anterior focus; and in the eyes of fishes
+and quadrupeds which he used for his food, he might have seen, and
+might have extracted, the beautiful lenses which they contain, and
+which he could not fail to regard as the principal agents in the vision
+of the animals to which they belonged. Curiosity might have prompted
+him to look through these remarkable lenses or spheres; and had he
+placed the lens of the smallest minnow, or that of the bird, the sheep,
+or the ox, in or before a circular aperture, he would have produced a
+microscope or microscopes of excellent quality and different magnifying
+powers. No such observations seem, however, to have been made; and even
+after the invention of glass, and its conversion into globular vessels,
+through which, when filled with any fluid, objects are magnified, the
+microscope remained undiscovered.
+
+
+A TRIAD OF CONTEMPORARY ASTRONOMERS.
+
+It is a remarkable fact in the history of astronomy (says Sir
+David Brewster), that three of its most distinguished professors
+were contemporaries. Galileo was the contemporary of Tycho during
+thirty-seven years, and of Kepler during the fifty-nine years
+of his life. Galileo was born seven years before Kepler, and
+survived him nearly the same time. We have not learned that the
+intellectual triumvirate of the age enjoyed any opportunity for mutual
+congratulation. What a privilege would it have been to have contrasted
+the aristocratic dignity of Tycho with the reckless ease of Kepler, and
+the manly and impetuous mien of the Italian sage!--_Brewster’s Life of
+Newton._
+
+
+A PEASANT ASTRONOMER.
+
+At about the same time that Goodricke discovered the variation of
+the remarkable periodical star Algol, or β Persei, one Palitzch, a
+farmer of Prolitz, near Dresden,--a peasant by station, an astronomer
+by nature,--from his familiar acquaintance with the aspect of the
+heavens, was led to notice, among so many thousand stars, Algol,
+as distinguished from the rest by its variation, and ascertained
+its period. The same Palitzch was also the first to re-discover
+the predicted comet of Halley in 1759, which he saw nearly a month
+before any of the astronomers, who, armed with their telescopes, were
+anxiously watching its return. These anecdotes carry us back to the era
+of the Chaldean shepherds.--_Sir John Herschel’s Outlines._
+
+
+SHIRBURN-CASTLE OBSERVATORY.
+
+Lord Macclesfield, the eminent mathematician, who was twelve years
+President of the Royal Society, built at his seat, Shirburn Castle
+in Oxfordshire, an Observatory, about 1739. It stood 100 yards south
+from the castle-gate, and consisted of a bed-chamber, a room for the
+transit, and the third for a mural quadrant. In the possession of
+the Royal Astronomical Society is a curious print representing two
+of Lord Macclesfield’s servants taking observations in the Shirburn
+observatory; they are Thomas Phelps, aged 82, who, from being a
+stable-boy to Lord-Chancellor Macclesfield, rose by his merit and
+genius to be appointed observer. His companion is John Bartlett,
+originally a shepherd, in which station he, by books and observation,
+acquired such a knowledge in computation, and of the heavenly bodies,
+as to induce Lord Macclesfield to appoint him assistant-observer in
+his observatory. Phelps was the person who, on December 23d, 1743,
+discovered the great comet, and made the first observation of it; an
+account of which is entered in the _Philosophical Transactions_, but
+not the name of the observer.
+
+
+LACAILLE’S OBSERVATORY.
+
+Lacaille, who made more observations than all his contemporaries put
+together, and whose researches will have the highest value as long as
+astronomy is cultivated, had an observatory at the Collège Mazarin,
+part of which is now the Palace of the Institute, at Paris.
+
+  For a long time it had been without observer or instruments;
+  under Napoleon’s reign it was demolished. Lacaille never used
+  to illuminate the wires of his instruments. The inner part of
+  his observatory was painted black; he admitted only the faintest
+  light, to enable him to see his pendulum and his paper: his left
+  eye was devoted to the service of looking to the pendulum, whilst
+  his right eye was kept shut. The latter was only employed to look
+  to the telescope, and during the time of observation never opened
+  but for this purpose. Thus the faintest light made him distinguish
+  the wires, and he very seldom felt the necessity of illuminating
+  them. Part of these blackened walls were visible long after the
+  demolition of the observatory, which took place somewhat about
+  1811.--_Professor Mohl._
+
+
+NICETY REQUIRED IN ASTRONOMICAL CALCULATIONS.
+
+In the _Edinburgh Review_, 1850, we find the following illustrations of
+the enormous propagation of minute errors:
+
+  The rod used in measuring a base-line is commonly about ten
+  feet long; and the astronomer may be said truly to apply that
+  very rod to mete the distance of the stars. An error in placing
+  a fine dot which fixes the length of the rod, amounting to
+  one-five-thousandth of an inch (the thickness of a single silken
+  fibre), will amount to an error of 70 feet in the earth’s diameter,
+  of 316 miles in the sun’s distance, and to 65,200,000 miles in
+  that of the nearest fixed star. Secondly, as the astronomer in his
+  observatory has nothing further to do with ascertaining lengths or
+  distances, except by calculation, his whole skill and artifice are
+  exhausted in the measurement of angles; for by these alone spaces
+  inaccessible can be compared. Happily, a ray of light is straight:
+  were it not so (in celestial spaces at least), there would be an
+  end of our astronomy. Now an angle of a second (3600 to a degree)
+  is a subtle thing. It has an apparent breadth utterly invisible to
+  the unassisted eye, unless accompanied with so intense a splendour
+  (_e. g._ in the case of a fixed star) as actually to raise by its
+  effect on the nerve of sight a spurious image having a sensible
+  breadth. A silkworm’s fibre, such as we have mentioned above,
+  subtends an angle of a second at 3½ feet distance; a cricket-ball,
+  2½ inches diameter, must be removed, in order to subtend a second,
+  to 43,000 feet, or about 8 miles, where it would be utterly
+  invisible to the sharpest sight aided even by a telescope of some
+  power. Yet it is on the measure of one single second that the
+  ascertainment of a sensible parallax in any fixed star depends;
+  and an error of one-thousandth of that amount (a quantity still
+  unmeasurable by the most perfect of our instruments) would place
+  the star too far or too near by 200,000,000,000 miles; a space
+  which light requires 118 days to travel.
+
+
+CAN STARS BE SEEN BY DAYLIGHT?
+
+Aristotle maintains that Stars may occasionally be seen in the
+Daylight, from caverns and cisterns, as through tubes. Pliny alludes
+to the same circumstance, and mentions that stars have been most
+distinctly recognised during solar eclipses. Sir John Herschel has
+heard it stated by a celebrated optician, that his attention was first
+drawn to astronomy by the regular appearance, at a certain hour, for
+several successive days, of a considerable star through the shaft of
+a chimney. The chimney-sweepers who have been questioned upon this
+subject agree tolerably well in stating that “they have never seen
+stars by day, but that when observed at night through deep shafts,
+the sky appeared quite near, and the stars larger.” Saussure states
+that stars have been seen with the naked eye in broad daylight, on
+the declivity of Mont Blanc, at an elevation of 12,757 feet, as he
+was assured by several of the alpine guides. The observer must be
+placed entirely in the shade, and have a thick and massive shade above
+his head, else the stronger light of the air will disperse the faint
+image of the stars; these conditions resembling those presented by the
+cisterns of the ancients, and the chimneys above referred to. Humboldt,
+however, questions the accuracy of these evidences, adding that in the
+Cordilleras of Mexico, Quito, and Peru, at elevations of 15,000 or
+16,000 feet above the sea-level, he never could distinguish stars by
+daylight. Yet, under the ethereally pure sky of Cumana, in the plains
+near the sea-shore, Humboldt has frequently been able, after observing
+an eclipse of Jupiter’s satellites, to find the planet again with the
+naked eye, and has most distinctly seen it when the sun’s disc was from
+18° to 20° above the horizon.
+
+
+LOST HEAT OF THE SUN.
+
+By the nature of our atmosphere, we are protected from the influence
+of the full flood of solar heat. The absorption of caloric by the air
+has been calculated at about one-fifth of the whole in passing through
+a column of 6000 feet, estimated near the earth’s surface. And we are
+enabled, knowing the increasing rarity of the upper regions of our
+gaseous envelope, in which the absorption is constantly diminishing,
+to prove that _about one-third of the solar heat is lost_ by vertical
+transmission through the whole extent of our atmosphere.--_J. D.
+Forbes, F.R.S._; _Bakerian Lecture_, 1842.
+
+
+THE LONDON MONUMENT USED AS AN OBSERVATORY.
+
+Soon after the completion of the Monument on Fish Street Hill, by Wren,
+in 1677, it was used by Hooke and other members of the Royal Society
+for astronomical purposes, but abandoned on account of the vibrations
+being too great for the nicety required in their observations. Hence
+arose _the report that the Monument was unsafe_, which has been revived
+in our time; “but,” says Elmes, “its scientific construction may bid
+defiance to the attacks of all but earthquakes for centuries to come.”
+This vibration in lofty columns is not uncommon. Captain Smythe, in his
+_Cycle of Celestial Objects_, tells us, that when taking observations
+on the summit of Pompey’s Pillar, near Alexandria, the mercury was
+sensibly affected by tremor, although the pillar is a solid.
+
+
+
+
+Geology and Paleontology.
+
+
+IDENTITY OF ASTRONOMY AND GEOLOGY.
+
+While the Astronomer is studying the form and condition and structure
+of the planets, in so far as the eye and the telescope can aid him, the
+Geologist is investigating the form and condition and structure of the
+planet to which he belongs; and it is from the analogy of the earth’s
+structure, as thus ascertained, that the astronomer is enabled to form
+any rational conjecture respecting the nature and constitution of the
+other planetary bodies. Astronomy and Geology, therefore, constitute
+the same science--the science of material or inorganic nature.
+
+When the astronomer first surveys the _concavity_ of the celestial
+vault, he finds it studded with luminous bodies differing in magnitude
+and lustre, some moving to the east and others to the west; while by
+far the greater number seem fixed in space; and it is the business of
+astronomers to assign to each of them its proper place and sphere, to
+determine their true distance from the earth, and to arrange them in
+systems throughout the regions of sidereal space.
+
+In like manner, when the geologist surveys the _convexity_ of his
+own globe, he finds its solid covering composed of rocks and beds of
+all shapes and kinds, lying at every possible angle, occupying every
+possible position, and all of them, generally speaking, at the same
+distance from the earth’s centre. Every where we see what was deep
+brought into visible relation with what was superficial--what is old
+with what is new--what preceded life with what followed it.
+
+Thus displayed on the surface of his globe, it becomes the business
+of the geologist to ascertain how these rocks came into their present
+places, to determine their different ages, and to fix the positions
+which they originally occupied, and consequently their different
+distances from the centre or the circumference of the earth. Raised
+from their original bed, the geologist must study the internal forces
+by which they were upheaved, and the agencies by which they were
+indurated; and when he finds that strata of every kind, from the
+primitive granite to the recent tertiary marine mud, have been thus
+brought within his reach, and prepared for his analysis, he reads their
+respective ages in the organic remains which they entomb; he studies
+the manner in which they have perished, and he counts the cycles of
+time and of life which they disclose.--_Abridged from the North-British
+Review_, No. 9.
+
+
+THE GEOLOGY OF ENGLAND
+
+is more interesting than that of other countries, because our island
+is in a great measure an epitome of the globe; and the observer who is
+familiar with our strata, and the fossil remains which they include,
+has not only prepared himself for similar inquiries in other countries,
+but is already, as it were, by anticipation, acquainted with what he is
+to find there.--_Transactions of the Geological Society._
+
+
+PROBABLE ORIGIN OF THE ENGLISH CHANNEL.
+
+The proposed construction of a submarine tunnel across the Straits
+of Dover has led M. Boué, For. Mem. Geol. Soc., to point out the
+probability that the English Channel has not been excavated by
+water-action only; but owes its origin to one of the lines of
+disturbance which have fissured this portion of the earth’s crust:
+and taking this view of the case, the fissure probably still exists,
+being merely filled with comparatively loose material, so as to prove
+a serious obstacle to any attempt made to drive through it a submarine
+tunnel.--_Proceedings of the Geological Society._
+
+
+HOW BOULDERS ARE TRANSPORTED TO GREAT HEIGHTS.
+
+Sir Roderick Murchison has shown that in Russia, when the Dwina is at
+its maximum height, and penetrates into the chinks of its limestone
+banks, when frozen and expanded it causes disruptions of the rock,
+the entanglement of stony fragments in the ice. In remarkable spring
+floods, the stream so expands that in bursting it throws up its icy
+fragments to 15 or 20 feet above the stream; and the waters subsiding,
+these lateral ice-heaps melt away, and leave upon the bank the
+rifled and angular blocks as evidence of the highest ice-mark. In
+Lapland, M. Böhtlingk assures us that he has found _large granitic
+boulders weighing several tons actually entangled and suspended, like
+birds’-nests, in the branches of pine-trees, at heights of 30 or 40
+feet above the summer level of the stream_![28]
+
+
+WHY SEA-SHELLS ARE FOUND AT GREAT HEIGHTS.
+
+The action of subterranean forces in breaking through and elevating
+strata of sedimentary rocks,--of which the coast of Chili, in
+consequence of a great earthquake, furnishes an example,--leads to the
+assumption that the pelagic shells found by MM. Bonpland and Humboldt
+on the ridge of the Andes, at an elevation of more than 15,000 English
+feet, may have been conveyed to so extraordinary a position, not by a
+rising of the ocean, but by the agency of volcanic forces capable of
+elevating into ridges the softened crust of the earth.
+
+
+SAND OF THE SEA AND DESERT.
+
+That sand is an assemblage of small stones may be seen with the eye
+unarmed with art; yet how few are equally aware of the synonymous
+nature of the sand of the sea and of the land! Quartz, in the form of
+sand, covers almost entirely the bottom of the sea. It is spread over
+the banks of rivers, and forms vast plains, even at a very considerable
+elevation above the level of the sea, as the desert of Sahara in
+Africa, of Kobi in Asia, and many others. This quartz is produced, at
+least in part, from the disintegration of the primitive granite rocks.
+The currents of water carry it along, and when it is in very small,
+light, and rounded grains, even the wind transports it from one place
+to another. The hills are thus made to move like waves, and a deluge of
+sand frequently inundates the neighbouring countries:
+
+    “So where o’er wide Numidian wastes extend,
+    Sudden the impetuous hurricanes descend.”--_Addison’s Cato._
+
+To illustrate the trite axiom, that nothing is lost, let us glance at
+the most important use of sand:
+
+  “Quartz in the form of sand,” observes Maltebrun, “furnishes, by
+  fusion, one of the most useful substances we have, namely glass,
+  which, being less hard than the crystals of quartz, can be made
+  equally transparent, and is equally serviceable to our wants and
+  to our pleasures. There it shines in walls of crystal in the
+  palaces of the great, reflecting the charms of a hundred assembled
+  beauties; there, in the hand of the philosopher, it discovers to us
+  the worlds that revolve above us in the immensity of space, and the
+  no less astonishing wonders that we tread beneath our feet.”
+
+
+PEBBLES.
+
+The various heights and situations at which Pebbles are found have
+led to many erroneous conclusions as to the period of changes of the
+earth’s surface. All the banks of rivers and lakes, and the shores of
+the sea, are covered with pebbles, rounded by the waves which have
+rolled them against each other, and which frequently seem to have
+brought them from a distance. There are also similar masses of pebbles
+found at very great elevations, to which the sea appears never to
+have been able to reach. We find them in the Alps at Valorsina, more
+than 6000 feet above the level of the sea; and on the mountain of Bon
+Homme, which is more than 1000 feet higher. There are some places
+little elevated above the level of the sea, which, like the famous
+plain of Crau, in Provence, are entirely paved with pebbles; while in
+Norway, near Quedlia, some mountains of considerable magnitude seem to
+be completely formed of them, and in such a manner that the largest
+pebbles occupy the summit, and their thickness and size diminish as you
+approach the base. We may include in the number of these confused and
+irregular heaps most of the depositions of matter brought by the river
+or sea, and left on the banks, and perhaps even those immense beds of
+sand which cover the centre of Asia and Africa. It is this circumstance
+which renders so uncertain the distinction, which it is nevertheless
+necessary to establish, between alluvial masses created before the
+commencement of history, and those which we see still forming under our
+own eyes.
+
+A charming monograph, entitled “Thoughts on a Pebble,” full of playful
+sentiment and graceful fancy, has been written by the amiable Dr.
+Mantell, the geologist.
+
+
+ELEVATION OF MOUNTAIN-CHAINS.
+
+Professor Ansted, in his _Ancient World_, thus characterises this
+phenomenon:
+
+  These movements, described in a few words, were doubtless going
+  on for many thousands and tens of thousands of revolutions of our
+  planet. They were accompanied also by vast but slow changes of
+  other kinds. The expansive force employed in lifting up, by mighty
+  movements, the northern portion of the continent of Asia, found
+  partial vent; and from partial subaqueous fissures there were
+  poured out the tabular masses of basalt occurring in Central India;
+  while an extensive area of depression in the Indian Ocean, marked
+  by the coral islands of the Laccadives, the Maldives, the great
+  Chagos bank, and some others, were in the course of depression by a
+  counteracting movement.
+
+Hitherto the processes of denudation and of elevation have been so
+far balanced as to preserve a pretty steady proportion of sea and dry
+land during geological ages; but if the internal temperature should
+be so far reduced as to be no longer capable of generating forces of
+expansion sufficient for this elevatory action, while the denuding
+forces should continue to act with unabated energy, the inevitable
+result would be, that every mountain-top would be in time brought low.
+No earthly barrier could declare to the ocean that there its proud
+waves should be stayed. Nothing would stop its ravages till all dry
+land should be laid prostrate, to form the bed over which it would
+continue to roll an uninterrupted sea.
+
+
+THE CHALK FORMATION.
+
+Mr. Horner, F.R.S., among other things in his researches in the Delta,
+considers it extremely probable that every particle of Chalk in the
+world has at some period been circulating in the system of a living
+animal.
+
+
+WEAR OF BUILDING-STONES.
+
+Professor Henry, in an account of testing the marbles used in building
+the Capitol at Washington, states that every flash of lightning
+produces an appreciable amount of nitric acid, which, diffused in
+rain-water, acts on the carbonate of lime; and from specimens subjected
+to actual freezing, it was found that in ten thousand years one inch
+would be worn from the blocks by the action of frost.
+
+  In 1839, a report of the examination of Sandstones, Limestones,
+  and Oolites of Britain was made to the Government, with a view to
+  the selection of the best material for building the new Houses
+  of Parliament. For this purpose, 103 quarries were described, 96
+  buildings in England referred to, many chemical analyses of the
+  stones were given, and a great number of experiments related,
+  showing, among other points, the cohesive power of each stone,
+  and the amount of disintegration apparent, when subjected to
+  Brard’s process. The magnesian limestone, or dolomite of Bolsover
+  Moor, was recommended, and finally adopted for the Houses; but
+  the selection does not appear to have been so successful as might
+  have been expected from the skill and labour of the investigation.
+  It may be interesting to add, that the publication of the above
+  Report (for which see _Year-Book of Facts_, 1840, pp. 78-80)
+  occasioned Mr. John Mallcott to remark in the _Times_ journal,
+  “that all stone made use of in the immediate neighbourhood of its
+  own quarries is more likely to endure that atmosphere than if it
+  be removed therefrom, though only thirty or forty miles:” and the
+  lapse of comparatively few years has proved the soundness of this
+  observation.[29]
+
+
+PHENOMENA OF GLACIERS ILLUSTRATED.
+
+Professor Tyndall, being desirous of investigating some of the
+phenomena presented by the large masses of mountain-ice,--those frozen
+rivers called Glaciers,--devised the plan of sending a destructive
+agent into the midst of a mass of ice, so as to break down its
+structure in the interior, in order to see if this method would reveal
+any thing of its internal constitution. Taking advantage of the bright
+weather of 1857, he concentrated a beam of sunlight by a condensing
+lens, so as to form the focus of the sun’s rays in the midst of a mass
+of ice. A portion of the ice was melted, but the surrounding parts
+shone out as brilliant stars, produced by the reflection of the faces
+of the crystalline structure. On examining these brilliant portions
+with a lens, Professor Tyndall discovered that the structure of the ice
+had been broken down in symmetrical forms of great beauty, presenting
+minute stars, surrounded by six petals, forming a beautiful flower, the
+plane being always parallel to the plane of congelation of the ice.
+He then prepared a piece of ice, by making both its surfaces smooth
+and parallel to each other. He concentrated in the centre of the ice
+the rays of heat from the electric light; and then, placing the piece
+of ice in the electric microscope, the disc revealed these beautiful
+ice-flowers.
+
+A mass of ice was crushed into fragments; the small fragments were then
+placed in a cup of wood; a hollow wooden die, somewhat smaller than the
+cup, was then pressed into the cup of ice-fragments by the pressure of
+a hydraulic press, and the ice-fragments were immediately united into
+a compact cup of nearly transparent ice. This pressure of fragments
+of ice into a solid mass explains the formation of the glaciers and
+their origin. They are composed of particles of ice or snow; as they
+descend the sides of the mountain, the pressure of the snow becomes
+sufficiently great to compress the mass into solid ice, until it
+becomes so great as to form the beautiful blue ice of the glaciers.
+This compression, however, will not form the solid mass unless the
+temperature of the ice be near that of freezing water. To prove this,
+the lecturer cooled a mass of ice, by wrapping it in a piece of tinfoil
+and exposing it for some time to a bath of the ethereal solution of
+solidified carbonic-acid gas, the coldest freezing mixture known. This
+cooled mass of ice was crushed to fragments, and submitted to the same
+pressure which the other fragments had been exposed to without cohering
+in the slightest degree.--_Lecture at the Royal Institution_, 1858.
+
+
+ANTIQUITY OF GLACIERS.
+
+The importance of glacier agency in the past as well as the present
+condition of the earth, is undoubtedly very great. One of our most
+accomplished and ingenious geologists has, indeed, carried back the
+existence of Glaciers to an epoch of dim antiquity, even in the
+reckoning of that science whose chronology is counted in millions of
+years. Professor Ramsay has shown ground for believing that in the
+fragments of rock that go to make up the conglomerates of the Permian
+strata, intermediate between the Old and the New Red Sandstone, there
+is still preserved a record of the action of ice, either in glaciers
+or floating icebergs, before those strata were consolidated.--_Saturday
+Review_, No. 142.
+
+
+FLOW OF THE MER DE GLACE.
+
+Michel Devouasson of Chamouni fell into a crevasse on the Glacier
+of Talefre, a feeder of the Mer de Glace, on the 29th of July 1836,
+and after a severe struggle extricated himself, leaving his knapsack
+below. The identical knapsack reappeared in July 1846, at a spot on
+the surface of the glacier _four thousand three hundred_ feet from
+the place where it was lost, as ascertained by Professor Forbes, who
+himself collected the fragments; thus indicating the rate of flow of
+the icy river in the intervening ten years.--_Quarterly Review_, No.
+202.
+
+
+THE ALLUVIAL LAND OF EGYPT: ANCIENT POTTERY.
+
+Mr. L. Horner, in his recent researches near Cairo, with the view of
+throwing light upon the geological history of the alluvial land of
+Egypt, obtained from the lowest part of the boring of the sediment at
+the colossal statue of Rameses, at a depth of thirty-nine feet, this
+curious relic of the ancient world; the boring instrument bringing up
+a fragment of pottery about an inch square and a quarter of an inch in
+thickness--the two surfaces being of a brick-red colour, the interior
+dark gray. According to Mr. Horner’s deductions, this fragment, having
+been found at a depth of 39 feet (if there be no fallacy in his
+reasoning), must be held to be a record of the existence of man 13,375
+years before A.D. 1858, reckoning by the calculated rate of increase of
+three inches and a half of alluvium in a century--11,517 years before
+the Christian era, and 7625 before the beginning assigned by Lepsius
+to the reign of Menos, the founder of Memphis. Moreover it proves in
+his opinion, that man had already reached a state of civilisation, so
+far at least as to be able to fashion clay into vessels, and to know
+how to harden it by the action of strong heat. This calculation is
+supported by the Chevalier Bunsen, who is of opinion that the first
+epochs of the history of the human race demand at the least a period
+of 20,000 years before our era as a fair starting-point in the earth’s
+history.--_Proceedings of Royal Soc._, 1858.
+
+  Upon this theory, a Correspondent, “An Old Indigo-Planter,” writes
+  to the _Athenæum_, No. 1509, the following suggestive note: “Having
+  lived many years on the banks of the Ganges, I have seen the stream
+  encroach on a village, undermining the bank where it stood, and
+  deposit, as a natural result, bricks, pottery, &c. in the bottom
+  of the stream. On one occasion, I am certain that the depth of
+  the stream where the bank was breaking was above 40 feet; yet in
+  three years the current of the river drifted so much, that a fresh
+  deposit of soil took place over the _débris_ of the village, and
+  the earth was raised to a level with the old bank. Now had our
+  traveller then obtained a bit of pottery from where it had lain for
+  only three years, could he reasonably draw the inference that it
+  had been made 13,000 years before?”
+
+
+SUCCESSIVE CHANGES OF THE TEMPLE OF SERAPIS.
+
+The Temple of Serapis at Puzzuoli, near Naples, is perhaps, of all
+the structures raised by the hands of man, the one which affords most
+instruction to a geologist. It has not only undergone a wonderful
+succession of changes in past time, but is still undergoing changes
+of condition. This edifice was exhumed in 1750 from the eastern shore
+of the Bay of Baiæ, consisting partly of strata containing marine
+shells with fragments of pottery and sculpture, and partly of volcanic
+matter of sub-aerial origin. Various theories were proposed in the
+last century to explain the perforations and attached animals observed
+on the middle zone of the three erect marble columns until recently
+standing; Goethe, among the rest, suggesting that a lagoon had once
+existed in the vestibule of the temple, filled during a temporary
+incursion of the sea with salt water, and that marine mollusca and
+annelids flourished for years in this lagoon at twelve feet or more
+above the sea-level.
+
+This hypothesis was advanced at a time when almost any amount of
+fluctuation in the level of the sea was thought more probable than
+the slightest alteration in the level of the solid land. In 1807 the
+architect Niccolini observed that the pavement of the temple was dry,
+except when a violent south wind was blowing; whereas, on revisiting
+the temple fifteen years later, he found the pavement covered by salt
+water twice every day at high tide. From measurements made from 1822
+to 1838, and thence to 1845, he inferred that the sea was gaining
+annually upon the floor of the temple at the rate of about one-third
+of an inch during the first period, and about three-fourths of an inch
+during the second. Mr. Smith of Jordan Hill, from his visits in 1819
+and 1845, found an average rise of about an inch annually, which was
+in accordance with visits made by Mr. Babbage in 1828, and Professor
+James Forbes in 1826 and 1843. In 1852 Signor Scaecchi, at the request
+of Sir Charles Lyell, compared the depth of water on the pavement with
+its level taken by him in 1839, and found that it had gained only 4½
+inches in thirteen years, and was not so deep as when MM. Niccolini
+and Smith measured it in 1845; from which he inferred that after 1845
+the downward movement of the land had ceased, and before 1852 had been
+converted into an upward movement.
+
+Arago and others maintained that the surface on which the temple
+stands has been depressed, has _remained under the sea, and has again
+been elevated_. Russager, however, contends that there is nothing in
+the vicinity of the temple, or in the temple itself, to justify this
+bold hypothesis. Every thing leads to the belief that the temple has
+remained unchanged in the position in which it was originally built;
+but that the sea rose, surrounded it to a height of at least twelve
+feet, and again retired; but the elevated position of the sea continued
+sufficiently long to admit of the animals boring the pillars. This view
+can even be proved historically; for Niccolini, in a memoir published
+in 1840, gives the heights of the level of the sea in the Bay of
+Naples for a period of 1900 years, and has with much acuteness proved
+his assertions historically. The correctness of Russager’s opinion,
+he states, can be demonstrated and reduced to figures by means of the
+dates collected by Niccolini.--See _Jameson’s Journal_, No. 58.
+
+At the present time the floor is always covered with sea-water. On the
+whole, there is little doubt that the ground has sunk upwards of two
+feet during the last half-century. This gradual subsidence confirms
+in a remarkable manner Mr. Babbage’s conclusions--drawn from the
+calcareous incrustations formed by the hot springs on the walls of the
+building and from the ancient lines of the water-level at the base of
+the three columns--that the original subsidence was not sudden, but
+slow and by successive movements.
+
+Sir Charles Lyell (who, in his _Principles of Geology_, has given a
+detailed account of the several upfillings of the temple) considers
+that when the mosaic pavement was re-constructed, the floor of the
+building must have stood about twelve feet above the level of 1838 (or
+about 11½ feet above the level of the sea), and that it had sunk about
+nineteen feet below that level before it was elevated by the eruption
+of Monte Nuovo.
+
+We regret to add, that the columns of the temple are no longer in
+the position in which they served so many years as a species of
+self-registering hydrometer: the materials have been newly arranged,
+and thus has been torn as it were from history a page which can never
+be replaced.
+
+
+THE GROTTO DEL CANE.
+
+This “Dog Grotto” has been so much cited for its stratum of
+carbonic-acid gas covering the floor, that all geological travellers
+who visit Naples feel an interest in seeing the wonder.
+
+This cavern was known to Pliny. It is continually exhaling from its
+sides and floor volumes of steam mixed with carbonic-acid gas; but the
+latter, from its greater specific gravity, accumulates at the bottom,
+and flows over the step of the door. The upper part of the cave,
+therefore, is free from the gas, while the floor is completely covered
+by it. Addison, on his visit, made some interesting experiments. He
+found that a pistol could not be fired at the bottom; and that on
+laying a train of gunpowder and igniting it on the outside of the
+cavern, the carbonic-acid gas “could not intercept the train of fire
+when it once began flashing, nor hinder it from running to the very
+end.” He found that a viper was nine minutes in dying on the first
+trial, and ten minutes on the second; this increased vitality being,
+in his opinion, attributable to the stock of air which it had inhaled
+after the first trial. Dr. Daubeny found that phosphorus would continue
+lighted at about two feet above the bottom; that a sulphur-match went
+out in a few minutes above it, and a wax-taper at a still higher level.
+The keeper of the cavern has a dog, upon which he shows the effects of
+the gas, which, however, are quite as well, if not better, seen in a
+torch, a lighted candle, or a pistol.
+
+“Unfortunately,” says Professor Silliman, “like some other grottoes,
+the enchantment of the ‘Dog Grotto’ disappears on a near view.” It is a
+little hole dug artificially in the side of a hill facing Lake Agnano:
+it is scarcely high enough for a person to stand upright in, and the
+aperture is closed by a door. Into this narrow cell a poor little dog
+is very unwillingly dragged and placed in a depression of the floor,
+where he is soon narcotised by the carbonic acid. The earth is warm to
+the hand, and the gas given out is very constant.
+
+
+THE WATERS OF THE GLOBE GRADUALLY DECREASING.
+
+This was maintained by M. Bory Saint Vincent, because the vast deserts
+of sand, mixed up with the salt and remains of marine animals, of which
+the surface of the globe is partly composed, were formerly inland seas,
+which have insensibly become dry. The Caspian, the Dead Sea, the Lake
+Baikal, &c. will become dry in their turn also, when their beds will
+be sandy deserts. The inland seas, whether they have only one outlet,
+as the Mediterranean, the Red Sea, the Baltic, &c., or whether they
+have several, as the Gulf of Mexico, the seas of O’Kotsk, of Japan,
+China, &c., will at some future time cease to communicate with the
+great basins of the ocean; they will become inland seas, true Caspians,
+and in due time will become likewise dry. On all sides the waters
+of rivers are seen to carry forward in their course the soil of the
+continent. Alluvial lands, deltas, banks of sand, form themselves near
+the coasts, and in the directions of the currents; madreporic animals
+lay the foundations of new lands; and while the straits become closed,
+while the depths of the sea fill up, the level of the sea, which it
+would seem natural should become higher, is sensibly lower. There is,
+therefore, an actual diminution of liquid matter.
+
+
+THE SALT LAKE OF UTAH.
+
+Lieutenant Gunnison, who has surveyed the great basin of the Salt
+Lake, states the water to be about one-third salt, which it yields
+on boiling. Its density is considerably greater than that of the Red
+Sea. One can hardly get the whole body below the surface: in a sitting
+position the head and shoulders will remain above the water, such is
+the strength of the brine; and on coming to the shore the body is
+covered with an incrustation of salt in fine crystals. During summer
+the lake throws on shore abundance of salt, while in winter it throws
+up Glauber salt plentifully. “The reason of this,” says Lieutenant
+Gunnison, “is left for the scientific to judge, and also what becomes
+of the enormous amount of fresh water poured into it by three or four
+large rivers,--Jordan, Bear, and Weber,--as there is no visible effect.”
+
+
+FORCE OF RUNNING WATER.
+
+It has been proved by experiment that the rapidity at the bottom
+of a stream is every where less than in any other part of it, and
+is greatest at the surface. Also, that in the middle of the stream
+the particles at the top move swifter than those at the sides. This
+slowness of the lowest and side currents is produced by friction; and
+when the rapidity is sufficiently great, the soil composing the sides
+and bottom gives way. If the water flows at the rate of three inches
+per second, it will tear up fine clay; six inches per second, fine
+sand; twelve inches per second, fine gravel; and three feet per second,
+stones the size of an egg.--_Sir Charles Lyell._
+
+
+THE ARTESIAN WELL OF GRENELLE AT PARIS.
+
+M. Peligot has ascertained that the Water of the Artesian Well of
+Grenelle contains not the least trace of air. Subterranean waters ought
+therefore to be _aerated_ before being used as aliment. Accordingly, at
+Grenelle, has been constructed a tower, from the top of which the water
+descends in innumerable threads, so as to present as much surface as
+possible to the air.
+
+The boring of this Well by the Messrs. Mulot occupied seven years, one
+month, twenty-six days, to the depth of 1794½ English feet, or 194½
+feet below the depth at which M. Elie de Beaumont foretold that water
+would be found. The sound, or borer, weighed 20,000 lb., and was treble
+the height of that of the dome of the Hôpital des Invalides at Paris.
+In May 1837, when the bore had reached 1246 feet 8 inches, the great
+chisel and 262 feet of rods fell to the bottom; and although these
+weighed five tons, M. Mulot tapped a screw on the head of the rods, and
+thus, connecting another length to them, after fifteen months’ labour,
+drew up the chisel. On another occasion, this chisel having been raised
+with great force, sank at one stroke 85 feet 3 inches into the chalk!
+
+  The depth of the Grenelle Well is nearly four times the height of
+  Strasburg Cathedral; more than six times the height of the Hôpital
+  des Invalides at Paris; more than four times the height of St.
+  Peter’s at Rome; nearly four times and a half the height of St.
+  Paul’s, and nine times the height of the Monument, London. Lastly,
+  suppose all the above edifices to be piled one upon each other,
+  from the base-line of the Well of Grenelle, and they would but
+  reach within 11½ feet of its surface.
+
+  MM. Elie de Beaumont and Arago never for a moment doubted the final
+  success of the work; their confidence being based on analogy, and
+  on a complete acquaintance with the geological structure of the
+  Paris basin, which is identical with that of the London basin
+  beneath the London clay.
+
+  In the duchy of Luxembourg is a well the depth of which surpasses
+  all others of the kind. It is upwards of 1000 feet more than that
+  of Grenelle near Paris.
+
+
+HOW THE GULF-STREAM REGULATES THE TEMPERATURE OF LONDON.
+
+Great Britain is almost exactly under the same latitude as Labrador, a
+region of ice and snow. Apparently, the chief cause of the remarkable
+difference between the two climates arises from the action of the great
+oceanic Gulf-Stream, whereby this country is kept constantly encircled
+with waters warmed by a West-Indian sun.
+
+  Were it not for this unceasing current from tropical seas, London,
+  instead of its present moderate average winter temperature of
+  6° above the freezing-point, might for many months annually be
+  ice-bound by a settled cold of 10° to 30° below that point, and
+  have its pleasant summer months replaced by a season so short
+  as not to allow corn to ripen, or only an alpine vegetation to
+  flourish.
+
+  Nor are we without evidence afforded by animal life of a greater
+  cold having prevailed in this country at a late geological period.
+  One case in particular occurs within eighty miles of London, at the
+  village of Chillesford, near Woodbridge, where, in a bed of clayey
+  sand of an age but little (geologically speaking) anterior to the
+  London gravel, Mr. Prestwich has found a group of fossil shells
+  in greater part identical with species now living in the seas of
+  Greenland and of similar latitudes, and which must evidently, from
+  their perfect condition and natural position, have existed in the
+  place where they are now met with.--_Lectures on the Geology of
+  Clapham, &c. by Joseph Prestwich, A.R.S., F.G.S._
+
+
+SOLVENT ACTION OF COMMON SALT AT HIGH TEMPERATURES.
+
+Forchhammer, after a long series of experiments, has come to the
+conclusion that Common Salt at high temperatures, such as prevailed at
+earlier periods of the earth’s history, acted as a general solvent,
+similarly to water at common temperatures. The amount of common salt
+in the earth would suffice to cover its whole surface with a crust ten
+feet in thickness.
+
+
+FREEZING CAVERN IN RUSSIA.
+
+This famous Cavern, at Ithetz Kaya-Zastchita, in the Steppes of the
+Kirghis, is employed by the inhabitants as a cellar. It has the very
+remarkable property of being so intensely cold during the hottest
+summers as to be then filled with ice, which disappearing with cold
+weather, is entirely gone in winter, when all the country is clad
+in snow. The roof is hung with ever-dripping solid icicles, and the
+floor may be called a stalagmite of ice and frozen earth. “If,” says
+Sir R. Murchison, “as we were assured, _the cold is greatest when the
+external air is hottest and driest_, that the fall of rain and a moist
+atmosphere produce some diminution of the cold in the cave, and that
+upon the setting-in of winter the ice disappears entirely,--then indeed
+the problem is very curious.” The peasants assert that in winter they
+could sleep in the cave without their sheepskins.
+
+
+INTERIOR TEMPERATURE OF THE EARTH: CENTRAL HEAT.
+
+By the observed temperature of mines, and that at the bottom of
+artesian wells, it has been established that the rate at which such
+temperature increases as we descend varies considerably in different
+localities, where the depths are comparatively small; but where the
+depths are great, we find a much nearer approximation to a common
+rate of increase, which, as determined by the best observation in the
+deepest mines, shafts, and artesian wells in Western Europe, is very
+nearly 1° F. _for an increase in depth of fifty feet_.--_W. Hopkins,
+M.A., F.R.S._
+
+Humboldt states that, according to tolerably coincident experiments in
+artesian wells, it has been shown that the heat increases on an average
+about 1° for every 54·5 feet. If this increase can be reduced to
+arithmetical relations, it will follow that a stratum of granite would
+be in a state of fusion at a depth of nearly twenty-one geographical
+miles, or between four and five times the elevation of the highest
+summit of the Himalaya.
+
+The following is the opinion of Professor Silliman:
+
+  That the whole interior portion of the earth, or at least a great
+  part of it, is an ocean of melted rock, agitated by violent winds,
+  though I dare not affirm it, is still rendered highly probable by
+  the phenomena of volcanoes. The facts connected with their eruption
+  have been ascertained and placed beyond a doubt. How, then, are
+  they to be accounted for? The theory prevalent some years since,
+  that they are caused by the combustion of immense coal-beds, is
+  puerile and now entirely abandoned. All the coal in the world could
+  not afford fuel enough for one of the tremendous eruptions of
+  Vesuvius.
+
+This observed increase of temperature in descending beneath the earth’s
+surface suggested the notion of a central incandescent nucleus still
+remaining in a state of fluidity from its elevated temperature. Hence
+the theory that the whole mass of the earth was formerly a molten
+fluid mass, the exterior portion of which, to some unknown depth, has
+assumed its present solidity by the radiation of heat into surrounding
+space, and its consequent refrigeration.
+
+The mathematical solution of this problem of Central Heat, assuming
+such heat to exist, tells us that though the central portion of the
+earth may consist of a mass of molten matter, the temperature of its
+surface is not thereby increased by more than the small fraction of
+a degree. Poisson has calculated that it would require _a thousand
+millions of centuries_ to reduce this fraction to a degree by half its
+present amount, supposing always the external conditions to remain
+unaltered. In such cases, the superficial temperature of the earth may,
+in fact, be considered to have approximated so near to its ultimate
+limit that it can be subject to no further sensible change.
+
+
+DISAPPEARANCE OF VOLCANIC ISLANDS.
+
+Many of the Volcanic Islands thrown up above the sea-level soon
+disappear, because the lavas and conglomerates of which they are formed
+spread over flatter surfaces, through the weight of the incumbent
+fluid; and the constant levelling process goes on below the sea by the
+action of tides and currents. Such islands as have effectually resisted
+this action are found to possess a solid framework of lava, supporting
+or defending the loose fragmentary materials.
+
+  Among the most celebrated of these phenomena in our times may be
+  mentioned the Isle of Sabrina, which rose off the coast of St.
+  Michael’s in 1811, attained a circumference of one mile and a
+  height of 300 feet, and disappeared in less than eight months; in
+  the following year there were eighty fathoms of water in its place.
+  In July 1831 appeared Graham’s Island off the coast of Sicily,
+  which attained a mile in circumference and 150 or 160 feet in
+  height; its formation much resembled that of Sabrina.
+
+The line of ancient subterranean fire which we trace on the
+Mediterranean coasts has had a strange attestation in Graham’s Island,
+which is also described as a volcano suddenly bursting forth in the mid
+sea between Sicily and Africa; burning for several weeks, and throwing
+up an isle, or crater-cone of scoriæ and ashes, which had scarcely been
+named before it was again lost by subsidence beneath the sea, leaving
+only a shoal-bank to attest this strange submarine breach in the
+earth’s crust, which thus mingled fire and water in one common action.
+
+Floating islands are not very rare: in 1827, one was seen twenty
+leagues to the east of the Azores; it was three leagues in width, and
+covered with volcanic products, sugar-canes, straw, and pieces of wood.
+
+
+PERPETUAL FIRE.
+
+Not far from the Deliktash, on the side of a mountain in Lycia, is the
+Perpetual Fire described some forty years since by Captain Beaufort.
+It was found by Lieutenant Spratt and Professor Forbes, thirty years
+later, as brilliant as ever, and somewhat increased; for besides the
+large flame in the corner of the ruins described by Beaufort, there
+were small jets issuing from crevices in the side of the crater-like
+cavity five or six feet deep. At the bottom was a shallow pool of
+sulphureous and turbid water, regarded by the Turks as a sovereign
+remedy for all skin complaints. The soot deposited from the flames was
+held to be efficacious for sore eyelids, and valued as a dye for the
+eyebrows. This phenomenon is described by Pliny as the flame of the
+Lycian Chimera.
+
+
+ARTESIAN FIRE-SPRINGS IN CHINA.
+
+According to the statement of the missionary Imbert, the
+Fire-Springs, “Ho-tsing” of the Chinese, which are sunk to obtain a
+carburetted-hydrogen gas for salt-boiling, far exceed our artesian
+springs in depth. These springs are very commonly more than 2000 feet
+deep; and a spring of continued flow was found to be 3197 feet deep.
+This natural gas has been used in the Chinese province Tse-tschuan for
+several thousand years; and “portable gas” (in bamboo-canes) has for
+ages been used in the city of Khiung-tscheu. More recently, in the
+village of Fredonia, in the United States, such gas has been used both
+for cooking and for illumination.
+
+
+VOLCANIC ACTION THE GREAT AGENT OF GEOLOGICAL CHANGE.
+
+  Mr. James Nasmyth observes, that “the floods of molten lava which
+  volcanoes eject are nothing less than remaining portions of what
+  was once the condition of the entire globe when in the igneous
+  state of its early physical history,--no one knows how many years
+  ago!
+
+  “When we behold the glow and feel the heat of molten lava, how
+  vastly does it add to the interest of the sight when we consider
+  that the heat we feel and the light we see are the residue of the
+  once universal condition of our entire globe, on whose _cooled
+  surface_ we _now_ live and have our being! But so it is; for if
+  there be one great fact which geological research has established
+  beyond all doubt, it is that we reside on the cooled surface of
+  what was once a molten globe, and that all the phenomena which
+  geology has brought to light can be most satisfactorily traced
+  to the successive changes incidental to its gradual cooling and
+  contraction.
+
+  “That the influx of the sea into the yet hot and molten interior of
+  the globe may occasionally occur, and enhance and vary the violence
+  of the phenomenon of volcanic action, there can be little doubt;
+  but the action of water in such cases is only _secondary_. But for
+  the pre-existing high temperature of the interior of the earth, the
+  influx of water would produce no such discharges of molten lava as
+  generally characterise volcanic eruptions. Molten lava is therefore
+  a true vestige of the Natural History of the Creation.”
+
+
+THE SNOW-CAPPED VOLCANO.
+
+It is but rarely that the elastic forces at work within the interior of
+our globe have succeeded in breaking through the spiral domes which,
+resplendent in the brightness of eternal snow, crown the summits of the
+Cordilleras; and even where these subterranean forces have opened a
+permanent communication with the atmosphere, through circular craters
+or long fissures, they rarely send forth currents of lava, but merely
+eject ignited scoriæ, steam, sulphuretted hydrogen gas, and jets of
+carbonic acid.--_Humboldt’s Cosmos_, vol. i.
+
+
+TRAVELS OF VOLCANIC DUST.
+
+On the 2d of September 1845, a quantity of Volcanic Dust fell in the
+Orkney Islands, which was supposed to have originated in an eruption of
+Hecla, in Iceland. It was subsequently ascertained that an eruption of
+that volcano took place on the morning of the above day (September 2),
+so as to leave no doubt of the accuracy of the conclusion. The dust had
+thus travelled about 600 miles!
+
+
+GREAT ERUPTIONS OF VESUVIUS.
+
+In the great eruption of Vesuvius, in August 1779, which Sir William
+Hamilton witnessed from his villa at Pausilippo in the bay of Naples,
+the volcano sent up white sulphureous smoke resembling bales of cotton,
+exceeding the height and size of the mountain itself at least four
+times; and in the midst of this vast pile of smoke, stones, scoriæ,
+and ashes were thrown up not less than 2000 feet. Next day a fountain
+of fire shot up with such height and brilliancy that the smallest
+objects could be clearly distinguished at any place within six miles
+or more of Vesuvius. But on the following day a more stupendous column
+of fire rose three times the height of Vesuvius (3700 feet), or more
+than two miles high. Among the huge fragments of lava thrown out during
+this eruption was a block 108 feet in circumference and 17 feet high,
+another block 66 feet in circumference and 19 feet high, and another 16
+feet high and 92 feet in circumference, besides thousands of smaller
+fragments. Sir William Hamilton suggests that from a scene of the above
+kind the ancient poets took their ideas of the giants waging war with
+Jupiter.
+
+The eruption of June 1794, which destroyed the greater part of the
+town of Torre del Greco, was, however, the most violent that has been
+recorded after the two great eruptions of 79 and 1631.
+
+
+EARTH-WAVES.
+
+The waves of an earthquake have been represented in their progress,
+and their propagation, through rocks of different density and
+elasticity; and the causes of the rapidity of propagation, and its
+diminution by the refraction, reflection, and interference of the
+oscillations have been mathematically investigated. Air, water, and
+earth waves follow the same laws which are recognised by the theory of
+motion, at all events in space; but the earth-waves are accompanied
+in their destructive action by discharges of elastic vapours, and
+of gases, and mixtures of pyroxene crystals, carbon, and infusorial
+animalcules with silicious shields. The more terrific effects are,
+however, when the earth-waves are accompanied by cleavage; and, as in
+the earthquake of Riobamba, when fissures alternately opened and closed
+again, so that men saved themselves by extending both arms, in order to
+prevent their sinking.
+
+As a remarkable example of the closing of a fissure, Humboldt mentions
+that, during the celebrated earthquake in 1851, in the Neapolitan
+province of Basilicata, a hen was found caught by both feet in the
+street-pavement of Barile, near Melfi.
+
+Mr. Hopkins has very correctly shown theoretically that the fissures
+produced by earthquakes are very instructive as regards the formation
+of veins and the phenomenon of dislocation, the more recent vein
+displacing the older formation.
+
+
+RUMBLINGS OF EARTHQUAKES.
+
+When the great earthquake of Coseguina, in Nicaragua, took place,
+January 23, 1835, the subterranean noise--the sonorous waves in the
+earth--was heard at the same time on the island of Jamaica and on the
+plateau of Bogota, 8740 feet above the sea, at a greater distance than
+from Algiers to London. In the eruptions of the volcano on the island
+of St. Vincent, April 30, 1812, at 2 A.M., a noise like the report of
+cannons was heard, without any sensible concussion of the earth, over a
+space of 160,000 geographical square miles. There have also been heard
+subterranean thunderings for two years without earthquakes.
+
+
+HOW TO MEASURE AN EARTHQUAKE-SHOCK.
+
+A new instrument (the Seismometer) invented for this purpose by
+M. Kreil, of Vienna, consists of a pendulum oscillating in every
+direction, but unable to turn round on its point of suspension; and
+bearing at its extremity a cylinder, which, by means of mechanism
+within it, turns on its vertical axis once in twenty-four hours. Next
+to the pendulum stands a rod bearing a narrow elastic arm, which
+slightly presses the extremity of a lead-pencil against the surface
+of the cylinder. As long as the pendulum is quiet, the pencil traces
+an uninterrupted line on the surface of the cylinder; but as soon as
+it oscillates, this line becomes interrupted and irregular, and these
+irregularities indicate the time of the commencement of an earthquake,
+together with its duration and intensity.[30]
+
+Elastic fluids are doubtless the cause of the slight and perfectly
+harmless trembling of the earth’s surface, which has often continued
+for several days. The focus of this destructive agent, the seat of
+the moving force, lies far below the earth’s surface; but we know as
+little of the extent of this depth as we know of the chemical nature
+of these vapours that are so highly compressed. At the edges of two
+craters,--Vesuvius and the towering rock which projects beyond the
+great abyss of Pichincha, near Quito,--Humboldt has felt periodic
+and very regular shocks of earthquakes, on each occasion from twenty
+to thirty seconds before the burning scoriæ or gases were erupted.
+The intensity of the shocks was increased in proportion to the time
+intervening between them, and consequently to the length of time in
+which the vapours were accumulating. This simple fact, which has
+been attested by the evidence of so many travellers, furnishes us
+with a general solution of the phenomenon, in showing that active
+volcanoes are to be considered as safety-valves for the immediate
+neighbourhood. There are instances in which the earth has been shaken
+for many successive days in the chain of the Andes, in South America.
+In certain districts, the inhabitants take no more notice of the number
+of earthquakes than we in Europe take of showers of rain; yet in such
+a district Bonpland and Humboldt were compelled to dismount, from the
+restiveness of their mules, because the earth shook in a forest for
+fifteen to eighteen minutes _without intermission_.
+
+
+EARTHQUAKES AND THE MOON.
+
+From a careful discussion of several thousand earthquakes which have
+been recorded between 1801 and 1850, and a comparison of the periods at
+which they occurred with the position of the moon in relation to the
+earth, M. Perry, of Dijon, infers that earthquakes may possibly be the
+result of attraction exerted by that body on the supposed fluid centre
+of our globe, somewhat similar to that which she exercises on the
+waters of the ocean; and the Committee of the Institute of France have
+reported favourably upon this theory.
+
+
+THE GREAT EARTHQUAKE OF LISBON.
+
+The eloquent Humboldt remarks, that the activity of an igneous
+mountain, however terrific and picturesque the spectacle may be which
+it presents to our contemplation, is always limited to a very small
+space. It is far otherwise with earthquakes, which, although scarcely
+perceptible to the eye, nevertheless simultaneously propagate their
+waves to a distance of many thousand miles. The great earthquake which
+destroyed the city of Lisbon, November 1st, 1755, was felt in the
+Alps, on the coast of Sweden, into the Antilles, Antigua, Barbadoes,
+and Martinique; in the great Canadian lakes, in Thuringia, in the
+flat country of northern Germany, and in the small inland lakes on
+the shores of the Baltic. Remote springs were interrupted in their
+flow,--a phenomenon attending earthquakes which had been noticed among
+the ancients by Demetrius the Callatian. The hot springs of Töplitz
+dried up and returned, inundating every thing around, and having their
+waters coloured with iron ochre. At Cadiz, the sea rose to an elevation
+of sixty-four feet; while in the Antilles, where the tide usually
+rises only from twenty-six to twenty-eight inches, it suddenly rose
+about twenty feet, the water being of an inky blackness. It has been
+computed that, on November 1st, 1755, a portion of the earth’s surface
+four times greater than that of Europe was simultaneously shaken.[31]
+As yet there is no manifestation of force known to us (says the
+vivid denunciation of the philosopher), including even the murderous
+invention of our own race, by which a greater number of people have
+been killed in the short space of a few minutes: 60,000 were destroyed
+in Sicily in 1693, from 30,000 to 40,000 in the earthquake of Riobamba
+in 1797, and probably five times as many in Asia Minor and Syria under
+Tiberius and Justinian the elder, about the years 19 and 526.
+
+
+GEOLOGICAL AGE OF THE DIAMOND.
+
+The discovery of Diamonds in Russia, far from the tropical zone, has
+excited much interest among geologists. In the detritus on the banks
+of the Adolfskoi, no fewer than forty diamonds have been found in the
+gold alluvium, only twenty feet above the stratum in which the remains
+of mammoths and rhinoceroses are found. Hence Humboldt has concluded
+that the formation of gold-veins, and consequently of diamonds, is
+comparatively of recent date, and scarcely anterior to the destruction
+of the mammoths. Sir Roderick Murchison and M. Verneuil have been led
+to the same result by different arguments.[32]
+
+
+WHAT WAS ADAMANT?
+
+Professor Tennant replies, that the Adamant described by Pliny was a
+sapphire, as proved by its form, and by the fact that when struck on
+an anvil by a hammer it would make an indentation in the metal. A true
+diamond, under such circumstances, would fly into a thousand pieces.
+
+
+WHAT IS COAL?
+
+The whole evidence we possess as to the nature of Coal proves it to
+have been originally a mass of vegetable matter. Its microscopical
+characters point to its having been formed on the spot in which we
+find it, to its being composed of vegetable tissues of various kinds,
+separated and changed by maceration, pressure, and chemical action,
+and to the introduction of its earthy matter, in a large number of
+instances, in a state of solution or fine molecular subdivision. Dr.
+Redfern, from whose communication to the British Association we quote,
+knows nothing to countenance the supposition that our coal-beds are
+mainly formed of coniferous wood, because the structures found in
+mother-coal, or the charcoal layer, have not the character of the
+glandular tissue of such wood, as has been asserted.
+
+Geological research has shown that the immense forests from which our
+coal is formed teemed with life. A frog as large as an ox existed in
+the swamps, and the existence of insects proves that the higher order
+of organic creation flourished at this epoch.
+
+It has been calculated that the available coal-beds in Lancashire
+amount in weight to the enormous sum of 8,400,000,000 tons. The total
+annual consumption of this coal, it has been estimated, amounts to
+3,400,120 tons; hence it is inferred that the coal-beds of Lancashire,
+at the present rate of consumption, will last 2470 years. Making
+similar calculations for the coal-fields of South Wales, the north of
+England, and Scotland, it will readily be perceived how ridiculous were
+the forebodings which lecturing geologists delighted to indulge in a
+few years ago.
+
+
+TORBANE-HILL COAL.
+
+The coal of Torbane Hill, Scotland, is so highly inflammable, that it
+has been disputed at law whether it be true coal, or only asphaltum,
+or bitumen. Dr. Redfern describes it as laminated, splitting with
+great ease horizontally, like many cannel coals, and like them it may
+be lighted at a candle. In all parts of the bed stigmaria and other
+fossil plants occur in greater numbers than in most other coals; their
+distinct vascular tissue may be easily recognised by a common pocket
+lens, and 65½ of the mass consists of carbon.
+
+Dr. Redfern considers that all our coals may be arranged in a scale
+having the Torbane-Hill coal at the top and anthracite at the bottom.
+Anthracite is almost pure carbon; Torbane Hill contains less fixed
+carbon than most other cannels: anthracite is very difficult to ignite,
+and gives out scarcely any gas; Torbane-Hill burns like a candle, and
+yields 3000 cubic feet of gas per ton, more than any other known coal,
+its gas being also of greatly superior illuminating power to any other.
+The only differences which the Torbane-Hill coal presents from others
+are differences of degree, not of kind. It differs from other coals
+in being the best gas-coal, and from other cannels in being the best
+cannel.
+
+
+HOW MALACHITE IS FORMED.
+
+The rich copper-ore of the Ural, which occurs in veins or masses,
+amid metamorphic strata associated with igneous rocks, and even in
+the hollows between the eruptive rocks, is worked in shafts. At the
+bottom of one of these, 280 feet deep, has been found an enormous
+irregularly-shaped botryoidal mass of _Malachite_ (Greek _malache_,
+mountain-green), sending off strings of green copper-ore. The upper
+surface of it is about 18 feet long and 9 wide; and it was estimated
+to contain 15,000 poods, or half a million pounds, of pure and compact
+malachite. Sir Roderick Murchison is of opinion that this wonderful
+subterraneous incrustation has been produced in the stalagmitic form,
+during a series of ages, by copper solutions emanating from the
+surrounding loose and sporous mass, and trickling through it to the
+lowest cavity upon the subjacent solid rock. Malachite is brought
+chiefly from one mine in Siberia; its value as raw material is nearly
+one-fourth that of the same weight of pure silver, or in a manufactured
+state three guineas per pound avoirdupois.[33]
+
+
+LUMPS OF GOLD IN SIBERIA.
+
+The gold mines south of Miask are chiefly remarkable for the large
+lumps or _pepites_ of gold which are found around the Zavod of
+Zarevo-Alexandroisk. Previous to 1841 were discovered here lumps of
+native gold; in that year a lump of twenty-four pounds was met with;
+and in 1843 a lump weighing about seventy-eight pounds English was
+found, and is now deposited with others in the Museum of the Imperial
+School of Mines at St. Petersburg.
+
+
+SIR ISAAC NEWTON UPON BURNET’S THEORY OF THE EARTH.
+
+In 1668, Dr. Thomas Burnet printed his _Theoria Telluris Sacra_,
+“an eloquent physico-theological romance,” says Sir David Brewster,
+“which was to a certain extent adopted even by Newton, Burnet’s
+friend. Abandoning, as some of the fathers had done, the hexaëmeron,
+or six days of Moses, as a physical reality, and having no knowledge
+of geological phenomena, he gives loose reins to his imagination,
+combining passages of Scripture with those of ancient authors, and
+presumptuously describing the future catastrophes to which the earth is
+to be exposed.” Previous to its publication, Burnet presented a copy
+of his book to Newton, and requested his opinion of the theory which
+it propounded. Newton took “exceptions to particular passages,” and
+a correspondence ensued. In one of Newton’s letters he treats of the
+formation of the earth, and the other planets, out of a general chaos
+of the figure assumed by the earth,--of the length of the primitive
+days,--of the formation of hills and seas, and of the creation of the
+two ruling lights as the result of the clearing up of the atmosphere.
+He considers the account of the creation in Genesis as adapted to the
+judgment of the vulgar. “Had Moses,” he says, “described the processes
+of creation as distinctly as they were in themselves, he would have
+made the narrative tedious and confused amongst the vulgar, and become
+a philosopher more than a prophet.” After referring to several “causes
+of meteors, such as the breaking out of vapours from below, before
+the earth was well hardened, the settling and shrinking of the whole
+globe after the upper regions or surface began to be hard,” Newton
+closes his letter with an apology for being tedious, which, he says,
+“he has the more reason to do, as he has not set down any thing he has
+well considered, or will undertake to defend.”--See the Letter in the
+Appendix to _Sir D. Brewster’s Life of Newton_, vol. ii.
+
+  The primitive condition of the earth, and its preparation for
+  man, was a subject of general speculation at the close of the
+  seventeenth century. Leibnitz, like his great rival (Newton),
+  attempted to explain the formation of the earth, and of the
+  different substances which composed it; and he had the advantage
+  of possessing some knowledge of geological phenomena: the earth
+  he regarded as having been originally a burning mass, whose
+  temperature gradually diminished till the vapours were condensed
+  into a universal ocean, which covered the highest mountains, and
+  gradually flowed into vacuities and subterranean cavities produced
+  by the consolidation of the earth’s crust. He regarded fossils
+  as the real remains of plants and animals which had been buried
+  in the strata; and, in speculating on the formation of mineral
+  substances, he speaks of crystals as the geometry of inanimate
+  nature.--_Brewster’s Life of Newton_, vol. ii. p. 100, note. (See
+  also “The Age of the Globe,” in _Things not generally Known_, p.
+  13.)
+
+
+“THE FATHER OF ENGLISH GEOLOGY.”
+
+In 1769 was born, the son of a yeoman of Oxfordshire, William
+Smith. When a boy he delighted to wander in the fields, collecting
+“pound-stones” (_Echinites_), “pundibs” (_Terebratulæ_), and other
+stony curiosities; and receiving little education beyond what he taught
+himself, he learned nothing of classics but the name. Grown to be a
+man, he became a land-surveyor and civil engineer, and was much engaged
+in constructing canals. While thus occupied, he observed that all the
+rocky masses forming the substrata of the country were gently inclined
+to the east and south-east,--that the red sandstones and marls above
+the _coal-measures_ passed below the beds provincially termed lias-clay
+and limestone--that these again passed underneath the sands, yellow
+limestone, and clays that form the table-land of the Coteswold Hills;
+while they in turn plunged beneath the great escarpment of chalk that
+runs from the coast of Dorsetshire northward to the Yorkshire shores
+of the German Ocean. He further observed that each formation of clay,
+sand, or limestone, held to a very great extent its own peculiar suite
+of fossils. The “snake-stones” (_Ammonites_) of the lias were different
+in form and ornament from those of the inferior oolite; and the
+shells of the latter, again, differed from those of the Oxford clay,
+Cornbrash, and Kimmeridge clay. Pondering much on these things, he
+came to the then unheard-of conclusion that each formation had been in
+its turn a sea-bottom, in the sediments of which lived and died marine
+animals now extinct, many specially distinctive of their own epochs in
+time.
+
+Here indeed was a discovery,--made, too, by a man utterly unknown to
+the scientific world, and having no pretension to scientific lore.
+“Strata Smith’s” find was unheeded for many a long year; but at length
+the first geologists of the day learned from the land-surveyor that
+superposition of strata is inseparably connected with the succession
+of life in time. Hooke’s grand vision was at length realised, and it
+was indeed possible “to build up a terrestrial chronology from rotten
+shells” imbedded in the rocks. Meanwhile he had constructed the first
+geological map of England, which has served as a basis for geological
+maps of all other parts of the world. William Smith was now presented
+by the Geological Society with the Wollaston Medal, and hailed as “the
+Father of English Geology.” He died in 1840. Till the manner as well
+as the fact of the first appearance of successive forms of life shall
+be solved, it is not easy to surmise how any discovery can be made in
+geology equal in value to that which we owe to the genius of William
+Smith.--_Saturday Review_, No. 140.
+
+
+DR. BUCKLAND’s GEOLOGICAL LABOURS.
+
+Sir Henry De la Beche, in his Anniversary Address to the Geological
+Society in 1848, on presenting the Wollaston Medal to Dr. Buckland,
+felicitously observed:
+
+  It may not be generally known that, while yet a child, at your
+  native town, Axminster in Devonshire, ammonites, obtained by your
+  father from the lime quarries in the neighbourhood, were presented
+  to your attention. As a scholar at Winchester, the chalk, with its
+  flints, was brought under your observation, and there it was that
+  your collections in natural history first began. Removed to Oxford,
+  as a scholar of Corpus Christi College, the future teacher of
+  geology in that University was fortunate in meeting with congenial
+  tastes in our colleague Mr. W. J. Broderip, then a student at Oriel
+  College. It was during your walks together to Shotover Hill, when
+  his knowledge of conchology was so valuable to you, enabling you
+  to distinguish the shells of the Oxford oolite, that you laid the
+  foundation for those field-lectures, forming part of your course
+  of geology at Oxford, which no one is likely to forget who has
+  been so fortunate at any time as to have attended them. The fruits
+  of your walks with Mr. Broderip formed the nucleus of that great
+  collection, more especially remarkable for the organic remains
+  it contains, which, after the labours of forty years, you have
+  presented to the Geological Museum at Oxford, in grave recollection
+  of the aid which the endowments of that University, and the leisure
+  of its vacations, had afforded you for extensive travelling during
+  a residence at Oxford of nearly forty-five years.
+
+
+DISCOVERIES OF M. AGASSIZ.[34]
+
+This great paleontologist, in the course of his ichthyological
+researches, was led to perceive that the arrangement by Cuvier
+according to organs did not fulfil its purpose with regard to fossil
+fishes, because in the lapse of ages the characteristics of their
+structures were destroyed. He therefore adopted the only other
+remaining plan, and studied the tissues, which, being less complex
+than the organs, are oftener found intact. The result was the very
+remarkable discovery, that the tegumentary membrane of fishes is so
+intimately connected with their organisation, that if the whole of the
+fish has perished except this membrane, it is practicable, by noting
+its characteristics, to reconstruct the animal in its most essential
+parts. Of the value of this principle of harmony, some idea may be
+formed from the circumstance, that on it Agassiz has based the whole
+of that celebrated classification of which he is the sole author, and
+by which fossil ichthyology has for the first time assumed a precise
+and definite shape. How essential its study is to the geologist appears
+from the remark of Sir Roderick Murchison, that “fossil fishes have
+every where proved the most exact chronometer of the age of rocks.”
+
+
+SUCCESSION OF LIFE IN TIME.
+
+In the Museum of Economic Geology, in Jermyn Street, may be seen ores,
+metals, rocks, and whole suites of fossils stratigraphically arranged
+in such a manner that, with an observant eye for form, all may easily
+understand the more obvious scientific meanings of the Succession
+of Life in Time, and its bearing on geological economies. It is
+perhaps scarcely an exaggeration to say, that the greater number of
+so-called educated persons are still ignorant of the meaning of this
+great doctrine. They would be ashamed not to know that there are many
+suns and material worlds besides our own; but the science, equally
+grand and comprehensible, that aims at the discovery of the laws that
+regulated the creation, extension, decadence, and utter extinction of
+many successive species, genera, and whole orders of life, is ignored,
+or, if intruded on the attention, is looked on as an uncertain and
+dangerous dream,--and this in a country which was almost the nursery of
+geology, and which for half a century has boasted the first Geological
+Society in the world.--_Saturday Review_, No. 140.
+
+
+PRIMITIVE DIVERSITY AND NUMBERS OF ANIMALS IN GEOLOGICAL TIMES.
+
+Professor Agassiz considers that the very fact of certain stratified
+rocks, even among the oldest formations, being almost entirely made
+up of fragments of organised beings, should long ago have satisfied
+the most sceptical that both _animal and vegetable life were as active
+and profusely scattered upon the whole globe at all times, and during
+all geological periods, as they are now_. No coral reef in the Pacific
+contains a larger amount of organic _débris_ than some of the limestone
+deposits of the tertiary, of the cretaceous, or of the oolitic, nay
+even of the paleozoic period; and the whole vegetable carpet covering
+the present surface of the globe, even if we were to consider only
+the luxuriant vegetation of the tropics, leaving entirely out of
+consideration the entire expanse of the ocean, as well as those tracts
+of land where, under less favourable circumstances, the growth of
+plants is more reduced,--would not form one single seam of workable
+coal to be compared to the many thick beds contained in the rocks of
+the carboniferous period alone.
+
+
+ENGLAND IN THE EOCENE PERIOD.
+
+Eocene is Sir Charles Lyell’s term for the lowest group of the Tertiary
+system in which the dawn of recent life appears; and any one who wishes
+to realise what was the aspect presented by this country during the
+Eocene period, need only go to Sheerness. If, leaving that place behind
+him, he walks down the Thames, keeping close to the edge of the water,
+he will find whole bushels of pyritised pieces of twigs and fruits.
+These fruits and twigs belong to plants nearly allied to the screw-pine
+and custard-apple, and to various species of palms and spice-trees
+which now flourish in the Eastern Archipelago. At the time they were
+washed down from some neighbouring land, not only crocodilian reptiles,
+but sharks and innumerable turtles, inhabited a sea or estuary which
+now forms part of the London district; and huge boa-constrictors glided
+amongst the trees which fringed the adjoining shores.
+
+Countless as are the ages which intervened between the Eocene period
+and the time when the little jawbones of Stonesfield were washed down
+to the place where they were to await the day when science should bring
+them again to light, not one mammalian genus which now lives upon our
+plane has been discovered amongst Eocene strata. We have existing
+families, but nothing more.--_Professor Owen._
+
+
+FOOD OF THE IGUANODON.
+
+Dr. Mantell, from the examination of the anterior part of the right
+side of the lower jaw of an Iguanodon discovered in a quarry in Tilgate
+Forest, Sussex, has detected an extraordinary deviation from all
+known types of reptilian organisation, and which could not have been
+predicated; namely, that this colossal reptile, which equalled in bulk
+the gigantic Edentata of South America, and like them was destined to
+obtain support from comminuted vegetable substances, was also furnished
+with a large prehensile tongue and fleshy lips, to serve as instruments
+for seizing and cropping the foliage and branches of trees; while
+the arrangement of the teeth as in the ruminants, and their internal
+structure, which resembles that of the molars of the sloth tribe in the
+vascularity of the dentine, indicate adaptations for the same purpose.
+
+Among the physiological phenomena revealed by paleontology, there
+is not a more remarkable one than this modification of the type of
+organisation peculiar to the class of reptiles to meet the conditions
+required by the economy of a lizard placed under similar physical
+relations; and destined to effect the same general purpose in the
+scheme of nature as the colossal Edentata of former ages and the large
+herbivorous mammalia of our own times.
+
+
+THE PTERODACTYL--THE FLYING DRAGON.
+
+The Tilgate beds of the Wealden series, just mentioned, have yielded
+numerous fragments of the most remarkable reptilian fossils yet
+discovered, and whose wonderful forms denote them to have thronged
+the shallow seas and bays and lagoons of the period. In the grounds
+of the Crystal Palace at Sydenham the reader will find restorations
+of these animals sufficiently perfect to illustrate this reptilian
+epoch. They include the _iguanodon_, an herbivorous lizard exceeding
+in size the largest elephant, and accompanied by the equally gigantic
+and carnivorous _megalosaurus_ (great saurian), and by the two yet more
+curious reptiles, the _pylæosaurus_ (forest, or weald, saurian) and the
+pterodactyl (from _pteron_, ‘wing,’ and _dactylus_, ‘a finger’), an
+enormous bat-like creature, now running upon the ground like a bird;
+its elevated body and long neck not covered with feathers, but with
+skin, naked, or resplendent with glittering scales; its head like that
+of a lizard or crocodile, and of a size almost preposterous compared
+with that of the body, with its long fore extremities stretched out,
+and connected by a membrane with the body and hind legs.
+
+Suddenly this mailed creature rose in the air, and realised or even
+surpassed in strangeness _the flying dragon of fable_: its fore-arms
+and its elongated wing-finger furnished with claws; hand and fingers
+extended, and the interspace filled up by a tough membrane; and its
+head and neck stretched out like that of the heron in its flight. When
+stationary, its wings were probably folded back like those of a bird;
+though perhaps, by the claws attached to its fingers, it might suspend
+itself from the branches of trees.
+
+
+MAMMALIA IN SECONDARY ROCKS.
+
+It was supposed till very lately that few if any Mammalia were to be
+found below the Tertiary rocks, _i. e._ those above the chalk; and this
+supposed fact was very comfortable to those who support the doctrine
+of “progressive development,” and hold, with the notorious _Vestiges
+of Creation_, that a fish by mere length of time became a reptile,
+a lemur an ape, and finally an ape a man. But here, as in a hundred
+other cases, facts, when duly investigated, are against their theory.
+A mammal jaw had been already discovered by Mr. Brodie on the shore at
+the back of Swanage Point, in Dorsetshire, when Mr. Beckles, F.G.S.,
+traced the vein from which this jaw had been procured, and found it
+to be a stratum about five inches thick, at the base of the Middle
+Purbeck beds; and after removing many thousand tons of rock, and laying
+bare an area of nearly 7000 square feet (the largest cutting ever made
+for purely scientific purposes), he found reptiles (tortoises and
+lizards) in hundreds; but the most important discovery was that of
+the jaws of at least fourteen different species of mammalia. Some of
+these were herbivorous, some carnivorous, connected with our modern
+shrews, moles, hedgehogs, &c.; but all of them perfectly developed and
+highly-organised quadrupeds. Ten years ago, no remains of quadrupeds
+were believed to exist in the Secondary strata. “Even in 1854,” says
+Sir Charles Lyell (in a supplement to the fifth edition of his _Manual
+of Elementary Geology_), “only six species of mammals from rocks older
+than the Tertiary were known in the whole world.” We now possess
+evidence of the existence of fourteen species, belonging to eight or
+nine genera, from the fresh-water strata of the Middle Purbeck Oolite.
+It would be rash now to fix a limit in past time to the existence of
+quadrupeds.--_The Rev. C. Kingsley._
+
+
+FOSSIL HUMAN BONES.
+
+In the paleontological collection in the British Museum is preserved
+a considerable portion of a human skeleton imbedded in a slab of
+rock, brought from Guadaloupe, and often referred to in opposition to
+the statement that hitherto _no fossil human hones have been found_.
+The presence of these bones, however, has been explained by the
+circumstance of a battle and the massacre of a tribe of Galtibis by the
+Caribs, which took place near the spot in which the bones were found
+about 130 years ago; for as the bodies of the slain were interred on
+the seashore, their skeletons may have been subsequently covered by
+sand-drift, which has since consolidated into limestone.
+
+It will be seen by reference to the _Philosophical Transactions_,
+that on the reading of the paper upon this discovery to the Royal
+Society, in 1814, Sir Joseph Banks, the president, considered the
+“fossil” to be of very modern formation, and that probably, from the
+contiguity of a volcano, the temperature of the water may have been
+raised at some time, and dissolving carbonate of lime readily, may
+have deposited about the skeleton in a comparatively short period hard
+and solid stone. Every person may be convinced of the rapidity of the
+formation and of the hardness of such stone by inspecting the inside of
+tea-kettles in which hard water is boiled.
+
+  Descriptions of petrifactions of human bodies appear to refer to
+  the conversion of bodies into adipocere, and not into stone. All
+  the supposed cases of petrifaction are probably of this nature.
+  The change occurs only when the coffin becomes filled with water.
+  The body, converted into adipocere, floats on the water. The
+  supposed cases of changes of position in the grave, bursting open
+  the coffin-lids, turning over, crossing of limbs, &c., formerly
+  attributed to the coming to life of persons buried who were not
+  dead, is now ascertained to be due to the same cause. The chemical
+  change into adipocere, and the evolution of gases, produce these
+  movements of dead bodies.--_Mr. Trail Green._
+
+
+THE MOST ANCIENT FISHES.
+
+Among the important results of Sir Roderick Murchison’s establishment
+of the Silurian system is the following:
+
+  That as the Lower Silurian group, often of vast dimensions, has
+  never afforded the smallest vestige of a Fish, though it abounds
+  in numerous species of the _marine_ classes,--corals, _crinoidea_,
+  _mollusca_, and _crustacea_; and as in Scandinavia and Russia,
+  where it is based on rocks void of fossils, its lowest stratum
+  contains _fucoids_ only,--Sir R. Murchison has, after fifteen years
+  of laborious research steadily directed to this point, arrived at
+  the conclusion, that a very long period elapsed after life was
+  breathed into the waters before the lowest order of vertebrata was
+  created; the earliest fishes being those of the Upper Silurian
+  rocks, which he was the first to discover, and which he described
+  “as the most ancient beings of their class which have yet been
+  brought to light.” Though the Lower Silurian rocks of various parts
+  of the world have since been ransacked by multitudes of prying
+  geologists, who have exhumed from them myriads of marine fossils,
+  not a single ichthyolite has been found in any stratum of higher
+  antiquity than the Upper Silurian group of Murchison.
+
+The most remarkable of all fossil fishes yet discovered have been found
+in the Old Red Sandstone cliffs at Dorpat, where the remains are so
+gigantic (one bone measuring _two feet nine inches_ in length) that
+they were at first supposed to belong to saurians.
+
+Sir Roderick’s examination of Russia has, in short, proved that _the
+ichthyolites and mollusks which, in Western Europe, are separately
+peculiar to smaller detached basins, were here (in the British Isles)
+cohabitants of many parts of the same great sea_.
+
+
+EXTINCT CARNIVOROUS ANIMALS OF BRITAIN.
+
+Professor Owen has thus forcibly illustrated the Carnivorous Animals
+which preyed upon and restrained the undue multiplication of the
+vegetable feeders. First we have the bear family, which is now
+represented in this country only by the badger. We were once blest,
+however, with many bears. One species seems to have been identical
+with the existing brown bear of the European continent. Far larger
+and more formidable was the gigantic cave-bear (_Ursus spelæus_),
+which surpassed in size his grisly brother of North America. The
+skull of the cave-bear differs very much in shape from that of its
+small brown relative just alluded to; the forehead, in particular,
+is much higher,--to be accounted for by an arrangement of air-cells
+similar to those which we have already remarked in the elephant. The
+cave-bear has left its remains in vast abundance in Germany. In our own
+caves, the bones of hyænas are found in greater quantities. The marks
+which the teeth of the hyæna make upon the bones which it gnaws are
+quite unmistakable. Our English hyænas had the most undiscriminating
+appetite, preying upon every creature, their own species amongst
+others. Wolves, not distinguishable from those which now exist in
+France and Germany, seem to have kept company with the hyænas; and the
+_Felis spelæa_, a sort of lion, but larger than any which now exists,
+ruled over all weaker brutes. Here, says Professor Owen, we have the
+original British Lion. A species of _Machairodus_ has left its remains
+at Kent’s Hole, near Torquay. In England we had also the beaver, which
+still lingers on the Danube and the Rhone, and a larger species, which
+has been called Trogontherium (gnawing beast), and a gigantic mole.
+
+
+THE GREAT CAVE TIGER OR LION OF BRITAIN.
+
+Remains of this remarkable animal of the drift or gravel period
+of this country have been found at Brentford and elsewhere near
+London. Speaking of this animal, Professor Owen observes, that “it
+is commonly supposed that the Lion, the Tiger, and the Jaguar are
+animals peculiarly adapted to a tropical climate. The genus Felis (to
+which these animals belong) is, however, represented by specimens
+in high northern latitudes, and in all the intermediate countries
+to the equator.” The chief condition necessary for the presence of
+such animals is an abundance of the vegetable-feeding animals. It
+is thus that the Indian tiger has been known to follow the herds of
+antelope and deer in the lofty mountains of the Himalaya to the verge
+of perpetual snow, and far into Siberia. “It need not, therefore,”
+continues Professor Owen, “excite surprise that indications should
+have been discovered in the fossil relics of the ancient mammalian
+population of Europe of a large feline animal, the contemporary of the
+mammoth, of the tichorrhine rhinoceros, of the great gigantic cave-bear
+and hyæna, and the slayer of the oxen, deer, and equine quadrupeds that
+so abounded during the same epoch.” The dimensions of this extinct
+animal equal those of the largest African lion or Bengal tiger; and
+some bones have been found which seem to imply that it had even more
+powerful limbs and larger paws.
+
+
+THE MAMMOTHS OF THE BRITISH ISLES.
+
+Dr. Buckland has shown that for long ages many species of carnivorous
+animals now extinct inhabited the caves of the British islands. In low
+tracts of Yorkshire, where tranquil lacustrine (lake-like) deposits
+have occurred, bones (even those of the lion) have been found so
+perfectly unbroken and unworn, in fine gravel (as at Market Weighton),
+that few persons would be disposed to deny that such feline and other
+animals once roamed over the British isles, as well as other European
+countries. Why, then, is it improbable that large elephants, with a
+peculiarly thick integument, a close coating of wool, and much long
+shaggy hair, should have been the occupants of wide tracts of Northern
+Europe and Asia? This coating, Dr. Fleming has well remarked, was
+probably as impenetrable to rain and cold as that of the monster ox of
+the polar circle. Such is the opinion of Sir Roderick Murchison, who
+thus accounts for the disappearance of the mammoths from Britain:
+
+  When we turn from the great Siberian continent, which, anterior
+  to its elevation, was the chief abode of the mammoths, and look
+  to the other parts of Europe, where their remains also occur, how
+  remarkable is it that we find the number of these creatures to be
+  justly proportionate to the magnitude of the ancient masses of land
+  which the labours of geologists have defined! Take the British
+  isles, for example, and let all their low, recently elevated
+  districts be submerged; let, in short, England be viewed as the
+  comparatively small island she was when the ancient estuary of the
+  Thames, including the plains of Hyde Park, Chelsea, Hounslow, and
+  Uxbridge, were under the water; when the Severn extended far into
+  the heart of the kingdom, and large eastern tracts of the island
+  were submerged,--and there will then remain but moderately-sized
+  feeding-grounds for the great quadrupeds whose bones are found in
+  the gravel of the adjacent rivers and estuaries.
+
+This limited area of subsistence could necessarily only keep up a small
+stock of such animals; and, just as we might expect, the remains of
+British mammoths occur in very small numbers indeed, when compared with
+those of the great charnel-houses of Siberia, into which their bones
+had been carried down through countless ages from the largest mass of
+surface which geological inquiries have yet shown to have been _dry
+land_ during that epoch.
+
+The remains of the mammoth, says Professor Owen, have been found in
+all, or almost all, the counties of England. Off the coast of Norfolk
+they are met with in vast abundance. The fishermen who go to catch
+turbot between the mouth of the Thames and the Dutch coast constantly
+get their nets entangled in the tusks of the mammoth. A collection
+of tusks and other remains, obtained in this way, is to be seen at
+Ramsgate. In North America, this gigantic extinct elephant must have
+been very common; and a large portion of the ivory which supplies
+the markets of Europe is derived from the vast mammoth graveyards of
+Siberia.
+
+The mammoth ranged at least as far north as 60°. There is no doubt
+that, at the present day, many specimens of the musk-ox are annually
+becoming imbedded in the mud and ice of the North-American rivers.
+
+It is curious to observe, that the mammoth teeth which are met with
+in caves generally belonged to young mammoths, who probably resorted
+thither for shelter before increasing age and strength emboldened them
+to wander far afield.
+
+
+THE RHINOCEROS AND HIPPOPOTAMUS OF ENGLAND.
+
+The mammoth was not the only giant that inhabited England in the
+Pliocene or Upper Tertiary period. We had also here the _Rhinoceros
+tichorrhinus_, or “strongly walled about the nose,” remains of which
+have been discovered in enormous quantities in the brickfields about
+London. Pallas describes an entire specimen of this creature, which was
+found near Yakutsk, the coldest town on the globe. Another rhinoceros,
+_leptorrhinus_ (fine nose), dwelt with the elephant of Southern Europe.
+In Siberia has been discovered the Elaimotherium, forming a link
+between the rhinoceros and the horse.
+
+In the days of the mammoth, we had also in England a Hippopotamus,
+rather larger than the species which now inhabits the Nile. Of our
+British hippopotamus some remains were dug up by the workmen in
+preparing the foundations of the New Junior United Service Club-house,
+in Regent-street.
+
+
+THE ELEPHANT AND TORTOISE.
+
+The idea of an Elephant standing on the back of a Tortoise was often
+laughed at as an absurdity, until Captain Cautley and Dr. Falconer
+at length discovered in the hills of Asia the remains of a tortoise
+in a fossil state of such a size that an elephant could easily have
+performed the above feat.
+
+
+COEXISTENCE OF MAN AND THE MASTODON.
+
+Dr. C. F. Winslow has communicated to the Boston Society of Natural
+History the discovery of the fragment of a human cranium 180 feet below
+the surface of the Table Mountain, California. Now the mastodon’s
+bones being found in the same deposits, points very clearly to the
+probability of the appearance of the human race on the western
+portions of North America at least before the extinction of those huge
+creatures. Fragments of mastodon and _Elephas primigenius_ have been
+taken ten and twenty feet below the surface in the above locality;
+where this discovery of human and mastodon remains gives strength
+to the possible truth of an old Indian tradition,--the contemporary
+existence of the mammoth and aboriginals in this region of the globe.
+
+
+HABITS OF THE MEGATHERIUM.
+
+Much uncertainty has been felt about the habits of the Megatherium,
+or Great Beast. It has been asked whether it burrowed or climbed, or
+what it did; and difficulties have presented themselves on all sides of
+the question. Some have thought that it lived in trees as much larger
+than those which now exist as the Megatherium itself is larger than
+the common sloth.[35] This, however, is now known to be a mistake.
+It did not climb trees--it pulled them down; and in order to do this
+the hinder parts of its skeleton were made enormously strong, and
+its prehensile fore-legs formed so as to give it a tremendous power
+over any thing which it grasped. Dr. Buckland suggested that animals
+which got their living in this way had a very fair chance of having
+their heads broken. While Professor Owen was still pondering over this
+difficulty, the skull of a cognate animal, the Mylodon, came into
+his hands. Great was his delight when he found that the mylodon not
+only had his head broken, but broken in two different places, at two
+different times; and moreover so broken that the injury could only have
+been inflicted by some such agent as a fallen tree. The creature had
+recovered from the first blow, but had evidently died of the second.
+This tribe had, as it turns out, two skulls, an outer and an inner
+one--given them, as it would appear, expressly with a view to the very
+dangerous method in which they were intended to obtain their necessary
+food.
+
+The dentition of the megatherium is curious. The elephant gets teeth
+as he wants them. Nature provided for the comfort of the megatherium
+in another way. It did not get new teeth, but the old ones went on
+for ever growing as long as the animal lived; so that as fast as one
+grinding surface became useless, another supplied its place.
+
+
+THE DINOTHERIUM, OR TERRIBLE BEAST.
+
+The family of herbivorous Cetaceans are connected with the
+Pachydermata of the land by one of the most wonderful of all the
+extinct creatures with which geologists have made us acquainted.
+This is the _Dinotherium_, or Terrible Beast. The remains of this
+animal were found in Miocene sands at Eppelsheim, about forty miles
+from Darmstadt. It must have been larger than the largest extinct or
+living elephant. The most remarkable peculiarity of its structure is
+the enormous tusks, curving downwards and terminating its lower jaw.
+It appears to have lived in the water, where the immense weight of
+these formidable appendages would not be so inconvenient as on land.
+What these tusks were used for is a mystery; but perhaps they acted
+as pickaxes in digging up trees and shrubs, or as harrows in raking
+the bottom of the water. Dr. Buckland used to suggest that they were
+perhaps employed as anchors, by means of which the monster might
+fasten itself to the bank of a stream and enjoy a comfortable nap. The
+extreme length of the _Dinotherium_ was about eighteen feet. Professor
+Kemp, in his restoration of the animal, has given it a trunk like
+that of the elephant, but not so long, and the general form of the
+tapir.--_Professor Owen._
+
+
+THE GLYPTODON.
+
+There are few creatures which we should less have expected to find
+represented in fossil history by a race of gigantic brethren than the
+armadillo. The creature is so small, not only in size but in all its
+works and ways, that we with difficulty associate it with the idea of
+magnitude. Yet Sir Woodbine Parish has discovered evidences of enormous
+animals of this family having once dwelt in South America. The huge
+loricated (plated over) creature whose relics were first sent has
+received the name of Glyptodon, from its sculptured teeth. Unlike the
+small armadillos, it was unable to roll itself up into a ball; though
+an enormous carnivore which lived in those days must have made it
+sometimes wish it had the power to do so. When attacked, it must have
+crouched down, and endeavoured to make its huge shell as good a defence
+as possible.--_Professor Owen._
+
+
+INMATES OF AN AUSTRALIAN CAVERN.
+
+From the fossil-bone caverns in Wellington Valley, in 1830, were sent
+to Professor Owen several bones which belonged, as it turned out, to
+gigantic kangaroos, immensely larger than any existing species; to
+a kind of wombat, to formidable dasyures, and several other genera.
+It also appeared that the bones, which were those of herbivores, had
+evidently belonged to young animals, while those of the carnivores
+were full-sized; a fact which points to the relations between the two
+families having been any thing but agreeable to the herbivores.
+
+
+THE POUCH-LION OF AUSTRALIA.
+
+The _Thylacoleo_ (Pouch-Lion) was a gigantic marsupial carnivore, whose
+character and affinities Professor Owen has, with exquisite scientific
+tact, made out from very small indications. This monster, which had
+kangaroos with heads three feet long to feed on, must have been one of
+the most extraordinary animals of the antique world.
+
+
+THE CONEY OF SCRIPTURE.
+
+Paleontologists have pointed out the curious fact that the Hyrax,
+called ‘coney’ in our authorised version of the Bible, is really only
+a diminutive and hornless rhinoceros. Remains have been found at
+Eppelsheim which indicate an animal more like a gigantic Hyrax than
+any of the existing rhinoceroses. To this the name of _Acerotherium_
+(Hornless Beast) has been given.
+
+
+A THREE-HOOFED HORSE.
+
+Professor Owen describes the _Hipparion_, or Three-hoofed Horse, as the
+first representative of a family so useful to mankind. This animal,
+in addition to its true hoof, appears to have had two additional
+elementary hoofs, analogous to those which we see in the ox. The object
+of these no doubt was to enable the Hipparion to extricate his foot
+with greater ease than he otherwise could when it sank through the
+swampy ground on which he lived.
+
+
+TWO MONSTER CARNIVORES OF FRANCE.
+
+A huge carnivorous creature has been found in Miocene strata in
+France, in which country it preyed upon the gazelle and antelope. It
+must have been as large as a grisly bear, but in general appearance
+and teeth more like a gigantic dog. Hence the name of _Amphicyon_
+(Doubtful Dog) has been assigned to it. This animal must have derived
+part of its support from vegetables. Not so the coeval monster which
+has been called _Machairodus_ (Sabre-tooth). It must have been
+somewhat akin to the tiger, and is by far the most formidable animal
+which we have met with in our ascending progress through the extinct
+mammalia.--_Professor Owen._
+
+
+GEOLOGY OF THE SHEEP.
+
+No unequivocal fossil remains of the sheep have yet been found in
+the bone-caves, the drift, or the more tranquil stratified newer
+Pliocene deposits, so associated with the fossil bones of oxen,
+wild-boars, wolves, foxes, otters, &c., as to indicate the coevality
+of the sheep with those species, or in such an altered state as to
+indicate them to have been of equal antiquity. Professor Owen had his
+attention particularly directed to this point in collecting evidence
+for a history of British Fossil Mammalia. No fossil core-horns of the
+sheep have yet been any where discovered; and so far as this negative
+evidence goes, we may infer that the sheep is not geologically more
+ancient than man; that it is not a native of Europe, but has been
+introduced by the tribes who carried hither the germs of civilisation
+in their migrations westward from Asia.
+
+
+THE TRILOBITE.
+
+Among the earliest races we have those remarkable forms, the
+Trilobites, inhabiting the ancient ocean. These crustacea remotely
+resemble the common wood-louse, and like that animal they had the power
+of rolling themselves into a ball when attacked by an enemy. The eye of
+the trilobite is a most remarkable organ; and in that of one species,
+_Phacops caudatus_, not less than 250 lenses have been discovered. This
+remarkable optical instrument indicates that these creatures lived
+under similar conditions to those which surround the crustacea of the
+present day.--_Hunt’s Poetry of Science._
+
+
+PROFITABLE SCIENCE.
+
+In that strip of reddish colour which runs along the cliffs of Suffolk,
+and is called the Redcrag, immense quantities of cetacean remains have
+been found. Four different kinds of whales, little inferior in size to
+the whalebone whale, have left their bones in this vast charnel-house.
+In 1840, a singularly perplexing fossil was brought to Professor Owen
+from this Redcrag. No one could say what it was. He determined it to
+be the tooth of a cetacean, a unique specimen. Now the remains of
+cetaceans in the Suffolk crag have been discovered in such enormous
+quantities, that many thousands a-year are made by converting them into
+manure.
+
+
+EXTINCT GIGANTIC BIRDS OF NEW ZEALAND.
+
+In the islands of New Zealand have been found the bones of large
+extinct wingless Birds, belonging to the Post Tertiary or Recent
+system, which have been deposited by the action of rivers. The bird
+is named _Moa_ by the natives, and _Dinornis_ by naturalists: some
+of the bones have been found in two caves in the North Island, and
+have been sold by the natives at an extraordinary price. The caves
+occur in limestone rocks, and the bones are found beneath earth and
+a soft deposit of carbonate of lime. The largest of the birds is
+stated to have stood thirteen or fourteen feet, or twice the height
+of the ostrich; and its egg large enough to fill the hat of a man as
+a cup. Several statements have appeared of these birds being still
+in existence, but there is every reason to believe the Moa to be
+altogether extinct.
+
+An extensive collection of remains of these great wingless birds has
+been collected in New Zealand by Mr. Walter Mantell, and deposited in
+the British Museum. Among these bones Professor Owen has discovered a
+species which he regards as the most remarkable of the feathered class
+for its prodigious strength and massive proportions, and which he names
+_Dinornis elephantopus_, or elephant-footed, of which the Professor
+has been able to construct an entire lower limb: the length of the
+metatarsal bone is 9¼ inches, the breadth of the lower end being
+5-1/3 inches. The extraordinary proportions of the metatarsus of this
+wingless bird will, however, be still better understood by comparison
+with the same bone in the ostrich, in which the metatarsus is 19 inches
+in length, the breadth of its lower end being only 2½ inches. From
+the materials accumulated by Mr. Mantell, the entire skeleton of the
+_Dinornis elephantopus_ has been reconstructed; and now forms a worthy
+companion of the Megatherium and Mastodon in the gallery of fossil
+remains in the British Museum. This species of _Dinornis_ appears to
+have been restricted to the Middle Island of New Zealand.[36]
+
+Another specimen of the remains of the _Dinornis_ is preserved in the
+Museum of the Royal College of Surgeons, in Lincoln’s-Inn Fields; and
+the means by which the college obtained this valuable acquisition is
+thus graphically narrated by Mr. Samuel Warren, F.R.S.:
+
+  In the year 1839, Professor Owen was sitting alone in his study,
+  when a shabbily-dressed man made his appearance, announcing that he
+  had got a great curiosity, which he had brought from New Zealand,
+  and wished to dispose of to him. It had the appearance of an old
+  marrow-bone, about six inches in length, and rather more than
+  two inches in thickness, _with both extremities broken off_; and
+  Professor Owen considered that, to whatever animal it might have
+  belonged, the fragment must have lain in the earth for centuries.
+  At first he considered this same marrow-bone to have belonged to
+  an ox, at all events to a quadruped; for the wall or rim of the
+  bone was six times as thick as the bone of any bird, even of the
+  ostrich. He compared it with the bones in the skeleton of an ox, a
+  horse, a camel, a tapir, and every quadruped apparently possessing
+  a bone of that size and configuration; but it corresponded with
+  none. On this he very narrowly examined the surface of the bony
+  rim, and at length became satisfied that this fragment must have
+  belonged to _a bird_!--to one at least as large as an ostrich, but
+  of a totally different species; and consequently one never before
+  heard of, as an ostrich was by far the biggest bird known.
+
+  From the difference in the _strength_ of the bone, the ostrich
+  being unable to fly, so must have been unable this unknown bird;
+  and so our anatomist came to the conclusion that this old shapeless
+  bone indicated the former existence in New Zealand of some huge
+  bird, at least as great as an ostrich, but of a far heavier and
+  more sluggish kind. Professor Owen was confident of the validity
+  of his conclusions, but would communicate that confidence to
+  no one else; and notwithstanding attempts to dissuade him from
+  committing his views to the public, he printed his deductions
+  in the _Transactions of the Zoological Society for 1839_, where
+  fortunately they remain on record as conclusive evidence of the
+  fact of his having then made this guess, so to speak, in the dark.
+  He caused the bone, however, to be engraved; and having sent a
+  hundred copies of the engraving to New Zealand, in the hope of
+  their being distributed and leading to interesting results, he
+  patiently waited for three years,--viz. till the year 1842,--when
+  he received intelligence from Dr. Buckland, at Oxford, that a
+  great box, just arrived from New Zealand, consigned to himself,
+  was on its way, unopened, to Professor Owen, who found it filled
+  with bones, palpably of a bird, one of which bones was three feet
+  in length, and much more than double the size of any bone in the
+  ostrich!
+
+  And out of the contents of this box the Professor was positively
+  enabled to articulate almost the entire skeleton of a huge wingless
+  bird between TEN and ELEVEN feet in height, its bony structure in
+  strict conformity with the fragment in question; and that skeleton
+  may at any time be seen at the Museum of the College of Surgeons,
+  towering over, and nearly twice the height of, the skeleton of
+  an ostrich; and at its feet lying the old bone from which alone
+  consummate anatomical science had deduced such an astounding
+  reality,--the existence of an enormous extinct creature of the bird
+  kind, in an island where previously no bird had been known to exist
+  larger than a pheasant or a common fowl!--_Lecture on the Moral and
+  Intellectual Development of the present Age._[37]
+
+
+“THE MAESTRICHT SAURIAN FOSSIL” A FRAUD.
+
+In 1795, there was stated to have been discovered in the stone quarries
+adjoining Maestricht the remains of the gigantic _Mosœsaurus_ (Saurian
+of the Meuse), an aquatic reptile about twenty-five feet long, holding
+an intermediate place between the Monitors and Iguanas. It appears
+to have had webbed feet, and a tail of such construction as to have
+served for a powerful oar, and enabled the animal to stem the waves of
+the ocean, of which Cuvier supposed it to have been an inhabitant. It
+is thus referred to by Dr. Mantell, in his _Medals of Creation_: “A
+specimen, with the jaws and bones of the palate, now in the Museum at
+Paris, has long been celebrated; and is still the most precious relic
+of this extinct reptile hitherto discovered.” An admirable cast of this
+specimen is preserved in the British Museum, in a case near the bones
+of the Iguanodon. This is, however, useless, as Cuvier is proved to
+have been imposed upon in the matter.
+
+  M. Schlegel has reported to the French Academy of Sciences, that
+  he has ascertained beyond all doubt that the famous fossil saurian
+  of the quarries of Maestricht, described as a wonderful curiosity
+  by Cuvier, is nothing more than an impudent fraud. Some bold
+  impostor, it seems, in order to make money, placed a quantity of
+  bones in the quarries in such a way as to give them the appearance
+  of having been recently dug up, and then passed them off as
+  specimens of antediluvian creation. Being successful in this, he
+  went the length of arranging a number of bones so as to represent
+  an entire skeleton; and had thus deceived the learned Cuvier. In
+  extenuation of Cuvier’s credulity, it is stated that the bones were
+  so skilfully coloured as to make them look of immense antiquity,
+  and he was not allowed to touch them lest they should crumble to
+  pieces. But when M. Schlegel subjected them to rude handling, he
+  found that they were comparatively modern, and that they were
+  placed one by the other without that profound knowledge of anatomy
+  which was to have been expected from the man bold enough to execute
+  such an audacious fraud.
+
+
+“THE OLDEST PIECE OF WOOD UPON EARTH.”
+
+The most remarkable vegetable relic which the Lower Old Red Sandstone
+has given us is a small fragment of a coniferous tree of the Araucarian
+family, which formed one of the chief ornaments of the late Hugh
+Miller’s museum, and to which he used to point as the oldest piece
+of wood upon earth. He found it in one of the ichthyolite beds of
+Cromarty, and thus refers to it in his _Testimony of the Rocks_:
+
+  On what perished land of the early paleozoic ages did this
+  venerably antique tree cast root and flourish, when the extinct
+  genera Pterichthys and Coccoeteus were enjoying life by millions
+  in the surrounding seas, long ere the flora or fauna of the coal
+  measures had begun to be?
+
+  The same nodule which enclosed this lignite contained part of
+  another fossil, the well-marked scales of _Diplacanthus striatus_,
+  an ichthyolite restricted to the Lower Old Red Sandstone
+  exclusively. If there be any value in paleontological evidence,
+  this Cromarty lignite must have been deposited in a sea inhabited
+  by the Coccoeteus and Diplacanthus. It is demonstrable that, while
+  yet in a recent state, a Diplacanthus lay down and died beside it;
+  and the evidence in the case is unequivocally this, that in the
+  oldest portion of the oldest terrestrial flora yet known there
+  occurs the fragment of a tree quite as high in the scale as the
+  stately Norfolk-Island pine or the noble cedar of Lebanon.
+
+
+NO FOSSIL ROSE.
+
+Professor Agassiz, in a lecture upon the trees of America, states a
+remarkable fact in regard to the family of the rose,--which includes
+among its varieties not only many of the most beautiful flowers, but
+also the richest fruits, as the apple, pear, peach, plum, apricot,
+cherry, strawberry, raspberry, &c.,--namely, that _no fossil plants
+belonging to this family have ever been discovered by geologists_! This
+M. Agassiz regards as conclusive evidence that the introduction of this
+family of plants upon the earth was coeval with, or subsequent to, the
+creation of man, to whose comfort and happiness they seem especially
+designed by a wise Providence to contribute.
+
+
+CHANGES ON THE EARTH’S SURFACE.
+
+In the Imperial Library at Paris is preserved a manuscript work by
+an Arabian writer, Mohammed Karurini, who flourished in the seventh
+century of the Hegira, or at the close of the thirteenth century of
+our era. Herein we find several curious remarks on aerolites and
+earthquakes, and the successive changes of position which the land and
+sea have undergone. Of the latter class is the following beautiful
+passage from the narrative of Khidz, an allegorical personage:
+
+  I passed one day by a very ancient and wonderfully populous city,
+  and asked one of its inhabitants how long it had been founded. “It
+  is indeed a mighty city,” replied he; “we know not how long it
+  has existed, and our ancestors were on this subject as ignorant
+  as ourselves.” Five centuries afterwards, as I passed by the same
+  place, I could not perceive the slightest vestige of the city. I
+  demanded of a peasant who was gathering herbs upon its former site
+  how long it had been destroyed. “In sooth, a strange question,”
+  replied he; “the ground here has never been different from what you
+  now behold it.” “Was there not of old,” said I, “a splendid city
+  here?” “Never,” answered he, “so far as we have seen; and never
+  did our fathers speak to us of any such.” On my return there five
+  hundred years afterwards, _I found the sea in the same place_; and
+  on its shores were a party of fishermen, of whom I inquired how
+  long the land had been covered by the waters. “Is this a question,”
+  say they, “for a man like you? This spot has always been what it is
+  now.” I again returned five hundred years afterwards; the sea had
+  disappeared: I inquired of a man who stood alone upon the spot how
+  long this change had taken place, and he gave me the same answer as
+  I had received before. Lastly, on coming back again after an equal
+  lapse of time, I found there a flourishing city, more populous and
+  more rich in beautiful buildings than the city I had seen the first
+  time; and when I would fain have informed myself concerning its
+  origin, the inhabitants answered me, “Its rise is lost in remote
+  antiquity: we are ignorant how long it has existed, and our fathers
+  were on this subject as ignorant as ourselves.”
+
+This striking passage was quoted in the _Examiner_, in 1834. Surely in
+this fragment of antiquity we trace the “geological changes” of modern
+science.
+
+
+GEOLOGICAL TIME.
+
+Many ingenious calculations have been made to approximate the dates
+of certain geological events; but these, it must be confessed, are
+more amusing than instructive. For example, so many inches of silt are
+yearly laid down in the delta of the Mississippi--how many centuries
+will it have taken to accumulate a thickness of 30, 60, or 100 feet?
+Again, the ledges of Niagara are wasting at the rate of so many feet
+per century--how many years must the river have taken to cut its way
+back from Queenstown to the present Falls? Again, lavas and melted
+basalts cool, according to the size of the mass, at the rate of so many
+degrees in a given time--how many millions of years must have elapsed,
+supposing an original igneous condition of the earth, before its crust
+had attained a state of solidity? or further, before its surface had
+cooled down to the present mean temperature? For these and similar
+computations, the student will at once perceive we want the necessary
+uniformity of factor; and until we can bring elements of calculation as
+exact as those of astronomy to bear on geological chronology, it will
+be better to regard our “eras” and “epochs” and “systems” as so many
+terms, indefinite in their duration, but sufficient for the magnitude
+of the operations embraced within their limits.--_Advanced Textbook of
+Geology, by David Page, F.G.S._
+
+M. Rozet, in 1841, called attention to the fact, that the causes which
+have produced irregularities in the structure of the globe have not yet
+ceased to act, as is proved by earthquakes, volcanic eruptions, slow
+and continuous movements of the crust of the earth in certain regions,
+&c. We may, therefore, yet see repeated the great catastrophes which
+the surface of the earth has undergone anteriorly to the historical
+period.
+
+At the meeting of the British Association in 1855, Mr. Hopkins excited
+much controversy by his startling speculation--that 9000 years ago
+the site on which London now stands was in the torrid zone; and that,
+according to perpetual changes in progress, the whole of England would
+in time arrive within the Arctic circle.
+
+
+CURIOUS CAUSE OF CHANGE OF LEVEL.
+
+Professor Hennessey, in 1857, _found the entire mass of rock and
+hill on which the Armagh Observatory is erected to be slightly, but
+to an astronomer quite perceptibly, tilted or canted, at one season
+to the east, at another to the west_. This he at first attributed to
+the varying power of the sun’s radiation to heat and expand the rock
+throughout the year; but he subsequently had reason to attribute it
+rather to the infiltration of water to the parts where the clay-slate
+and limestone rocks met, the varying quantity of the water exerting
+a powerful hydrostatic energy by which the position of the rock is
+slightly varied.
+
+Now Armagh and its observatory stand at the junction of the mountain
+limestone with the clay-slate, having, as it were, one leg on the
+former and the other on the latter; and both rocks probably reach
+downwards 1000 or 2000 feet. When rain falls, the one will absorb
+more water than the other; both will gain an increase of conductive
+power; but the one which has absorbed most water will have the greatest
+increase, and being thus the better conductor, will _draw a greater
+portion of heat from the hot nucleus below to the surface_--will
+become, in fact, temporarily hotter, and, as a consequence, _expand
+more than the other_. In a word, _both rocks will expand at the wet
+season; but the best conductor, or most absorbent rock, will expand
+most, and seem to tilt the hill to one side; at the dry season it will
+subside most, and the hill will seem to be tilted in the opposite
+direction_.
+
+The fact is curious, and not less so are the results deducible from
+it. First, hills are higher at one season than another; a fact we
+might have supposed, but never could have ascertained by measurement.
+Secondly, they are highest, not, as we should have supposed, at the
+hottest season, but at the wettest. Thirdly, it is from the _different
+rates_ of expansion of different rocks that this has been discovered.
+Fourthly, it is by converse with the _heavens_ that it has been made
+known to us. A variation of probably half a second, or less, in the
+right ascension of three or four stars, observed at different seasons,
+no doubt revealed the fact to the sagacious astronomer of Armagh, and
+even enabled him to divine its cause.
+
+  Professor Hennessey observes in connection with this phenomenon,
+  that a very small change of ellipticity would suffice to lay
+  bare or submerge extensive tracts of the globe. If, for example,
+  the mean ellipticity of the ocean increased from 1/300 to 1/299,
+  the level of the sea would be raised at the equator by about 228
+  feet, while under the parallel of 52° it would be depressed by
+  196 feet. Shallow seas and banks in the latitudes of the British
+  isles, and between them and the pole, would thus be converted into
+  dry land, while low-lying plains and islands near the equator
+  would be submerged. If similar phenomena occurred during early
+  periods of geological history, they would manifestly influence the
+  distribution of land and water during these periods; and with such
+  a direction of the forces as that referred to, they would tend to
+  increase the proportion of land in the polar and temperate regions
+  of the earth, as compared with the equatorial regions during
+  successive geological epochs. Such maps as those published by Sir
+  Charles Lyell on the distribution of land and water in Europe
+  during the Tertiary period, and those of M. Elie de Beaumont,
+  contained in Beaudant’s _Geology_, would, if sufficiently extended,
+  assist in verifying or disproving these views.
+
+
+THE OUTLINES OF CONTINENTS NOT FIXED.
+
+Continents (says M. Agassiz) are only a patchwork formed by the
+emergence and subsidence of land. These processes are still going on
+in various parts of the globe. Where the shores of the continent are
+abrupt and high, the effect produced may be slight, as in Norway and
+Sweden, where a gradual elevation is going on without much alteration
+in their outlines. But if the continent of North America were to be
+depressed 1000 feet, nothing would remain of it except a few islands,
+and any elevation would add vast tracts to its shores.
+
+The west of Asia, comprising Palestine and the country about Ararat and
+the Caspian Sea, is below the level of the ocean, and a rent in the
+mountain-chains by which it is surrounded would transform it into a
+vast gulf.
+
+
+
+
+Meteorological Phenomena.
+
+
+THE ATMOSPHERE.
+
+A philosopher of the East, with a richness of imagery truly oriental,
+describes the Atmosphere as “a spherical shell which surrounds our
+planet to a depth which is unknown to us, by reason of its growing
+tenuity, as it is released from the pressure of its own superincumbent
+mass. Its upper surface cannot be nearer to us than 50, and can
+scarcely be more remote than 500, miles. It surrounds us on all sides,
+yet we see it not; it presses on us with a load of fifteen pounds on
+every square inch of surface of our bodies, or from seventy to one
+hundred tons on us in all, yet we do not so much as feel its weight.
+Softer than the softest down, more impalpable than the finest gossamer,
+it leaves the cobweb undisturbed, and scarcely stirs the lightest
+flower that feeds on the dew it supplies; yet it bears the fleets of
+nations on its wings around the world, and crushes the most refractory
+substances with its weight. When in motion, its force is sufficient to
+level the most stately forests and stable buildings with the earth--to
+raise the waters of the ocean into ridges like mountains, and dash the
+strongest ships to pieces like toys. It warms and cools by turns the
+earth and the living creatures that inhabit it. It draws up vapours
+from the sea and land, retains them dissolved in itself or suspended
+in cisterns of clouds, and throws them down again as rain or dew when
+they are required. It bends the rays of the sun from their path to
+give us the twilight of evening and of dawn; it disperses and refracts
+their various tints to beautify the approach and the retreat of the orb
+of day. But for the atmosphere sunshine would burst on us and fail us
+at once, and at once remove us from midnight darkness to the blaze of
+noon. We should have no twilight to soften and beautify the landscape;
+no clouds to shade us from the searching heat; but the bald earth, as
+it revolved on its axis, would turn its tanned and weakened front to
+the full and unmitigated rays of the lord of day. It affords the gas
+which vivifies and warms our frames, and receives into itself that
+which has been polluted by use and is thrown off as noxious. It feeds
+the flames of life exactly as it does that of the fire--it is in both
+cases consumed and affords the food of consumption--in both cases it
+becomes combined with charcoal, which requires it for combustion and is
+removed by it when this is over.”
+
+
+UNIVERSALITY OF THE ATMOSPHERE.
+
+It is only the girdling, encircling air that flows above and around all
+that makes the whole world kin. The carbonic acid with which to-day
+our breathing fills the air, to-morrow makes its way round the world.
+The date-trees that grow round the falls of the Nile will drink it in
+by their leaves; the cedars of Lebanon will take of it to add to their
+stature; the cocoa-nuts of Tahiti will grow rapidly upon it; and the
+palms and bananas of Japan will change it into flowers. The oxygen we
+are breathing was distilled for us some short time ago by the magnolias
+of the Susquehanna; the great trees that skirt the Orinoco and the
+Amazon, the giant rhododendrons of the Himalayas, contributed to it,
+and the roses and myrtles of Cashmere, the cinnamon-tree of Ceylon, and
+the forest, older than the Flood, buried deep in the heart of Africa,
+far behind the Mountains of the Moon. The rain we see descending was
+thawed for us out of the icebergs which have watched the polar star for
+ages; and the lotus-lilies have soaked up from the Nile, and exhaled as
+vapour, snows that rested on the summits of the Alps.--_North-British
+Review._
+
+
+THE HEIGHT OF THE ATMOSPHERE.
+
+The differences existing between that which appertains to the air
+of heaven (the realms of universal space) and that which belongs to
+the strata of our terrestrial atmosphere are very striking. It is
+not possible, as well-attested facts prove, perfectly to explain
+the operations at work in the much-contested upper boundaries of
+our atmosphere. The extraordinary lightness of whole nights in the
+year 1831, during which small print might be read at midnight in
+the latitudes of Italy and the north of Germany, is a fact directly
+at variance with all we know according to the researches on the
+crepuscular theory and the height of the atmosphere. The phenomena
+of light depend upon conditions still less understood; and their
+variability at twilight, as well as in the zodiacal light, excite our
+astonishment. Yet the atmosphere which surrounds the earth is not
+thicker in proportion to the bulk of our globe than the line of a
+circle two inches in diameter when compared with the space which it
+encloses, or the down on the skin of a peach in comparison with the
+fruit inside.
+
+
+COLOURS OF THE ATMOSPHERE.
+
+Pure air is blue, because, according to Newton, the molecules of the
+air have the thickness necessary to reflect blue rays. When the sky
+is not perfectly pure, and the atmosphere is blended with perceptible
+vapours, the diffused light is mixed with a large proportion of
+white. As the moon is yellow, the blue of the air assumes somewhat
+of a greenish tinge, or, in other words, becomes blended with
+yellow.--_Letter from Arago to Humboldt_; _Cosmos_, vol. iii.
+
+
+BEAUTY OF TWILIGHT.
+
+This phenomenon is caused by the refraction of solar light enabling
+it to diffuse itself gradually over our hemisphere, obscured by the
+shades of night, long before the sun appears, even when that luminary
+is eighteen degrees below our horizon. It is towards the poles that
+this reflected splendour of the great luminary is longest visible,
+often changing the whole of the night into a magic day, of which the
+inhabitants of southern Europe can form no adequate conception.
+
+
+HOW PASCAL WEIGHED THE ATMOSPHERE.
+
+Pascal’s treatise on the weight of the whole mass of air forms the
+basis of the modern science of Pneumatics. In order to prove that the
+mass of air presses by its weight on all the bodies which it surrounds,
+and also that it is elastic and compressible, he carried a balloon,
+half-filled with air, to the top of the Puy de Dome, a mountain about
+500 toises above Clermont, in Auvergne. It gradually inflated itself
+as it ascended, and when it reached the summit it was quite full,
+and swollen as if fresh air had been blown into it; or, what is the
+same thing, it swelled in proportion as the weight of the column of
+air which pressed upon it was diminished. When again brought down it
+became more and more flaccid, and when it reached the bottom it resumed
+its original condition. In the nine chapters of which the treatise
+consists, Pascal shows that all the phenomena and effects hitherto
+ascribed to the horror of a vacuum arise from the weight of the mass
+of air; and after explaining the variable pressure of the atmosphere
+in different localities and in its different states, and the rise of
+water in pumps, he calculates that the whole mass of air round our
+globe weighs 8,983,889,440,000,000,000 French pounds.--_North-British
+Review_, No. 2.
+
+It seems probable, from many indications, that the greatest height at
+which visible clouds _ever exist_ does not exceed ten miles; at which
+height the density of the air is about an eighth part of what it is at
+the level of the sea.--_Sir John Herschel._
+
+
+VARIATIONS OF CLIMATE.
+
+History informs us that many of the countries of Europe which now
+possess very mild winters, at one time experienced severe cold during
+this season of the year. The Tiber, at Rome, was often frozen over, and
+snow at one time lay for forty days in that city. The Euxine Sea was
+frozen over every winter during the time of Ovid, and the rivers Rhine
+and Rhone used to be frozen over so deep that the ice sustained loaded
+wagons. The waters of the Tiber, Rhine, and Rhone, now flow freely
+every winter; ice is unknown in Rome, and the waves of the Euxine dash
+their wintry foam uncrystallised upon the rocks. Some have ascribed
+these climate changes to agriculture--the cutting down of dense
+forests, the exposing of the unturned soil to the summer’s sun, and the
+draining of great marshes. We do not believe that such great changes
+could be produced on the climate of any country by agriculture; and we
+are certain that no such theory can account for the contrary change of
+climate--from warm to cold winters--which history tells us has taken
+place in other countries than those named. Greenland received its name
+from the emerald herbage which once clothed its valleys and mountains;
+and its east coast, which is now inaccessible on account of perpetual
+ice heaped upon its shores, was in the eleventh century the seat of
+flourishing Scandinavian colonies, all trace of which is now lost. Cold
+Labrador was named Vinland by the Northmen, who visited it A.D. 1000,
+and were charmed with its then mild climate. The cause of these changes
+is an important inquiry.--_Scientific American._
+
+
+AVERAGE CLIMATES.
+
+When we consider the numerous and rapid changes which take place in
+our climate, it is a remarkable fact, that _the mean temperature of
+a place remains nearly the same_. The winter may be unusually cold,
+or the summer unusually hot, while the mean temperature has varied
+even less than a degree. A very warm summer is therefore likely to
+be accompanied with a cold winter; and in general, if we have any
+long period of cold weather, we may expect a similar period at a
+higher temperature. In general, however, in the same locality the
+relative distribution over summer and winter undergoes comparatively
+small variations; therefore every point of the globe has an average
+climate, though it is occasionally disturbed by different atmospheric
+changes.--_North-British Review_, No. 49.
+
+
+THE FINEST CLIMATE IN THE WORLD.
+
+Humboldt regards the climate of the Caspian Sea as the most salubrious
+in the world: here he found the most delicious fruits that he saw
+during his travels; and such was the purity of the air, that polished
+steel would not tarnish even by night exposure.
+
+
+THE PUREST ATMOSPHERES.
+
+The cloudless purity and transparency of the atmosphere, which last
+for eight months at Santiago, in Chili, are so great, that Lieutenant
+Gilliss, with the first telescope ever constructed in America, having
+a diameter of seven inches, was clearly able to recognise the sixth
+star in the trapezium of Orion. If we are to rely upon the statements
+of the Rev. Mr. Stoddart, an American missionary, Oroomiah, in Persia,
+seems to be, in so far as regards the transparency of the atmosphere,
+the most suitable place in the world for an astronomical observatory.
+Writing to Sir John Herschel from that country, he mentions that he
+has been enabled to distinguish with the naked eye the satellites
+of Jupiter, the crescent of Venus, the rings of Saturn, and the
+constituent members of several double stars.
+
+
+SEA-BREEZES AND LAND-BREEZES ILLUSTRATED.
+
+When a fire is kindled on the hearth, we may, if we will observe the
+motes floating in the room, see that those nearest the chimney are the
+first to feel the draught and to obey it,--they are drawn into the
+blaze. The circle of inflowing air is gradually enlarged, until it is
+scarcely perceived in the remote parts of the room. Now the land is the
+hearth, the rays of the sun the fire, and the sea, with its cool and
+calm air, the room; and thus we have at our firesides the sea-breeze in
+miniature.
+
+When the sun goes down, the fire ceases; then the dry land commences
+to give off its surplus heat by radiation, so that by nine or ten
+o’clock it and the air above it are cooled below the sea temperature.
+The atmosphere on the land thus becomes heavier than that on the
+sea, and consequently there is a wind seaward, which we call the
+land-breeze.--_Maury._
+
+
+SUPERIOR SALUBRITY OF THE WEST.
+
+All large cities and towns have their best districts in the West;[38]
+which choice the French _savans_, Pelouze, Pouillet, Boussingault, and
+Elie de Beaumont, attribute to the law of atmospheric pressure. “When,”
+say they, “the barometric column rises, smoke and pernicious emanations
+rapidly evaporate in space.” On the contrary, smoke and noxious vapours
+remain in apartments, and on the surface of the soil. Now, of all
+winds, that which causes the greatest ascension of the barometric
+column is the east; and that which lowers it most is the west. When the
+latter blows, it carries with it to the eastern parts of the town all
+the deleterious gases from the west; and thus the inhabitants of the
+east have to support their own smoke and miasma, and those brought by
+western winds. When, on the contrary, the east wind blows, it purifies
+the air by causing to ascend the pernicious emanations which it cannot
+drive to the west. Consequently, the inhabitants of the west receive
+pure air, from whatever part of the horizon it may arrive; and as the
+west winds are most prevalent, they are the first to receive the air
+pure, and as it arrives from the country.
+
+
+FERTILISATION OF CLOUDS.
+
+As the navigator cruises in the Pacific Ocean among the islands of
+the trade-wind region, he sees gorgeous piles of cumuli, heaped up in
+fleecy masses, not only capping the island hills, but often overhanging
+the lowest islet of the tropics, and even standing above coral patches
+and hidden reefs; “a cloud by day.” to serve as a beacon to the lonely
+mariner out there at sea, and to warn him of shoals and dangers which
+no lead nor seaman’s eye has ever seen or sounded. These clouds, under
+favourable circumstances, may be seen gathering above the low coral
+island, preparing it for vegetation and fruitfulness in a very striking
+manner. As they are condensed into showers, one fancies that they are
+a sponge of the most exquisite and delicately elaborated material, and
+that he can see, as they “drop down their fatness,” the invisible but
+bountiful hand aloft that is pressing and squeezing it out.--_Maury._
+
+
+BAROMETRIC MEASUREMENT.
+
+We must not place too implicit a dependence on Barometrical
+Measurements. Ermann in Siberia, and Ross in the Antarctic Seas, have
+demonstrated the existence of localities on the earth’s surface where
+a permanent depression of the barometer prevails to the astonishing
+extent of nearly an inch.
+
+
+GIGANTIC BAROMETER.
+
+In the Great Exhibition Building of 1851 was a colossal Barometer, the
+tube and scale reaching from the floor of the gallery nearly to the top
+of the building, and the rise and fall of the indicating fluid being
+marked by feet instead of by tenths of inches. The column of mercury,
+supported by the pressure of the atmosphere, communicated with a
+perpendicular tube of smaller bore, which contained a coloured fluid
+much lighter than mercury. When a diminution of atmospheric pressure
+occurred, the mercury in the large tube descended, and by its fall
+forced up the coloured fluid in the smaller tube; the fall of the one
+being indicated in a magnified ratio by the rise in the other.
+
+
+THE ATMOSPHERE COMPARED TO A STEAM-ENGINE.
+
+In this comparison, by Lieut. Maury, the South Seas themselves, in all
+their vast intertropical extent, are the boiler for the engine, and the
+northern hemisphere is its condenser. The mechanical power exerted by
+the air and the sun in lifting water from the earth, in transporting
+it from one place to another, and in letting it down again, is
+inconceivably great. The utilitarian who compares the water-power that
+the Falls of Niagara would afford if applied to machinery is astonished
+at the number of figures which are required to express its equivalent
+in horse-power. Yet what is the horse-power of the Niagara, falling
+a few steps, in comparison with the horse-power that is required to
+lift up as high as the clouds and let down again all the water that is
+discharged into the sea, not only by this river, but by all the other
+rivers in the world? The calculation has been made by engineers; and
+according to it, the force of making and lifting vapour from each area
+of one acre that is included on the surface of the earth, is equal to
+the power of thirty horses; and for the whole of the earth, it is 800
+times greater than all the water-power in Europe.
+
+
+HOW DOES THE RAIN-MAKING VAPOUR GET FROM THE SOUTHERN INTO THE NORTHERN
+HEMISPHERE?
+
+This comes with such regularity, that our rivers never go dry, and
+our springs fail not, because of the exact _compensation_ of the
+grand machine of _the atmosphere_. It is exquisitely and wonderfully
+counterpoised. Late in the autumn of the north, throughout its
+winter, and in early spring, the sun is pouring his rays with the
+greatest intensity down upon the seas of the southern hemisphere; and
+this powerful engine, which we are contemplating, is pumping up the
+water there with the greatest activity; at the same time, the mean
+temperature of the entire southern hemisphere is about 10° higher than
+the northern. The heat which this heavy evaporation absorbs becomes
+latent, and with the moisture is carried through the upper regions
+of the atmosphere until it reaches our climates. Here the vapour is
+formed into clouds, condensed and precipitated; the heat which held
+their water in the state of vapour is set free, and becomes sensible
+heat; and it is that which contributes so much to temper our winter
+climate. It clouds up in winter, turns warm, and we say we are going
+to have falling weather: that is because the process of condensation
+has already commenced, though no rain or snow may have fallen. Thus we
+feel this southern heat, that has been collected by the rays of the sun
+by the sea, been bottled away by the winds in the clouds of a southern
+summer, and set free in the process of condensation in our northern
+winter.
+
+Thus the South Seas should supply mainly the water for the engine just
+described, while the northern hemisphere condenses it; we should,
+therefore, have more rain in the northern hemisphere. The rivers tell
+us that we have, at least on the land; for the great water-courses of
+the globe, and half the fresh water in the world, are found on the
+north side of the equator. This fact is strongly corroborative of this
+hypothesis. To evaporate water enough annually from the ocean to cover
+the earth, on the average, five feet deep with rain; to transport it
+from one zone to another; and to precipitate it in the right places at
+suitable times and in the proportions due,--is one of the offices of
+the grand atmospherical machine. This water is evaporated principally
+from the torrid zone. Supposing it all to come thence, we shall have
+encircling the earth a belt of ocean 3000 miles in breadth, from which
+this atmosphere evaporates a layer of water annually sixteen feet in
+depth. And to hoist up as high as the clouds, and lower down again,
+all the water, in a lake sixteen feet deep and 3000 miles broad and
+24,000 long, is the yearly business of this invisible machinery. What a
+powerful engine is the atmosphere! and how nicely adjusted must be all
+the cogs and wheels and springs and _compensations_ of this exquisite
+piece of machinery, that it never wears out nor breaks down, nor fails
+to do its work at the right time and in the right way!--_Maury._
+
+
+THE PHILOSOPHY OF RAIN.
+
+To understand the philosophy of this beautiful and often sublime
+phenomenon, a few facts derived from observation and a long train of
+experiments must be remembered.
+
+  1. Were the atmosphere every where at all times at a uniform
+  temperature, we should never have rain, or hail, or snow. The water
+  absorbed by it in evaporation from the sea and the earth’s surface
+  would descend in an imperceptible vapour, or cease to be absorbed
+  by the air when it was once fully saturated.
+
+  2. The absorbing power of the atmosphere, and consequently its
+  capability to retain humidity, is proportionally greater in warm
+  than in cold air.
+
+  3. The air near the surface of the earth is warmer than it is in
+  the region of the clouds. The higher we ascend from the earth, the
+  colder do we find the atmosphere. Hence the perpetual snow on very
+  high mountains in the hottest climate.
+
+Now when, from continued evaporation, the air is highly saturated
+with vapour, though it be invisible and the sky cloudless, if its
+temperature is suddenly reduced by cold currents descending from
+above or rushing from a higher to a lower latitude, its capacity to
+retain moisture is diminished, clouds are formed, and the result is
+rain. Air condenses as it cools, and, like a sponge filled with water
+and compressed, pours out the water which its diminished capacity
+cannot hold. What but Omniscience could have devised such an admirable
+arrangement for watering the earth?
+
+
+INORDINATE RAINY CLIMATE.
+
+The climate of the Khasia mountains, which lie north-east from
+Calcutta, and are separated by the valley of the Burrampooter River
+from the Himalaya range, is remarkable for the inordinate fall of
+rain--the greatest, it is said, which has ever been recorded. Mr. Yule,
+an English gentleman, established that in the single month of August
+1841 there fell 264 inches of rain, or 22 feet, of which 12½ feet
+fell in the space of five consecutive days. This astonishing fact is
+confirmed by two other English travellers, who measured 30 inches of
+rain in twenty-four hours, and during seven months above 500 inches.
+This great rain-fall is attributed to the abruptness of the mountains
+which face the Bay of Bengal, and the intervening flat swamps 200 miles
+in extent. The district of the excessive rain is extremely limited; and
+but a few degrees farther west, rain is said to be almost unknown, and
+the winter falls of snow to seldom exceed two inches.
+
+
+HOW DOES THE NORTH WIND DRIVE AWAY RAIN?
+
+We may liken it to a wet sponge, and the decrease of temperature
+to the hand that squeezes that sponge. Finally, reaching the cold
+latitudes, all the moisture that a dew-point of zero, and even far
+below, can extract, is wrung from it; and this air then commences “to
+return according to his circuits” as dry atmosphere. And here we can
+quote Scripture again: “The north wind driveth away rain.” This is a
+meteorological fact of high authority and great importance in the study
+of the circulation of the atmosphere.--_Maury._
+
+
+SIZE OF RAIN-DROPS.
+
+The Drops of Rain vary in their size, perhaps from the 25th to the ¼ of
+an inch in diameter. In parting from the clouds, they precipitate their
+descent till the increasing resistance opposed by the air becomes equal
+to their weight, when they continue to fall with uniform velocity. This
+velocity is, therefore, in a certain ratio to the diameter of the
+drops; hence thunder and other showers in which the drops are large
+pour down faster than a drizzling rain. A drop of the 25th part of an
+inch, in falling through the air, would, when it had arrived at its
+uniform velocity, only acquire a celerity of 11½ feet per second; while
+one of ¼ of an inch would equal a velocity of 33½ feet.--_Leslie._
+
+
+RAINLESS DISTRICTS.
+
+In several parts of the world there is no rain at all. In the Old World
+there are two districts of this kind: the desert of Sahara in Africa,
+and in Asia part of Arabia, Syria, and Persia; the other district lies
+between north latitude 30° and 50°, and between 75° and 118° of east
+longitude, including Thibet, Gobiar Shama, and Mongolia. In the New
+World the rainless districts are of much less magnitude, occupying two
+narrow strips on the shores of Peru and Bolivia, and on the coast of
+Mexico and Guatemala, with a small district between Trinidad and Panama
+on the coast of Venezuela.
+
+
+ALL THE RAIN IN THE WORLD.
+
+The Pacific Ocean and the Indian Ocean may be considered as one sheet
+of water covering an area quite equal in extent to one half of that
+embraced by the whole surface of the earth; and the total annual fall
+of rain on the earth’s surface is 186,240 cubic imperial miles. Not
+less than three-fourths of the vapour which makes this rain comes from
+this waste of waters; but, supposing that only half of this quantity,
+that is 93,120 cubic miles of rain, falls upon this sea, and that that
+much at least is taken up from it again as vapour, this would give
+255 cubic miles as the quantity of water which is daily lifted up and
+poured back again into this expanse. It is taken up at one place,
+and rained down at another; and in this process, therefore, we have
+agencies for multitudes of partial and conflicting currents, all, in
+their set strength, apparently as uncertain as the winds.
+
+The better to appreciate the operation of such agencies in producing
+currents in the sea, imagine a district of 255 square miles to be set
+apart in the midst of the Pacific Ocean as the scene of operations
+for one day; then conceive a machine capable of pumping up in the
+twenty-four hours all the water to the depth of one mile in this
+district. The machine must not only pump up and bear off this immense
+quantity of water, but it must discharge it again into the sea on the
+same day, but at some other place.
+
+All the great rivers of America, Europe, and Asia are lifted up by the
+atmosphere, and flow in invisible streams back through the air to their
+sources among the hills; and through channels so regular, certain, and
+well defined, that the quantity thus conveyed one year with the other
+is nearly the same: for that is the quantity which we see running down
+to the ocean through these rivers; and the quantity discharged annually
+by each river is, as far as we can judge, nearly a constant.--_Maury._
+
+
+AN INCH OF RAIN ON THE ATLANTIC.
+
+Lieutenant Maury thus computes the effect of a single Inch of Rain
+falling upon the Atlantic Ocean. The Atlantic includes an area of
+twenty-five millions of square miles. Suppose an inch of rain to fall
+upon only one-fifth of this vast expanse. It would weigh, says our
+author, three hundred and sixty thousand millions of tons: and the salt
+which, as water, it held in solution in the sea, and which, when that
+water was taken up as vapour, was left behind to disturb equilibrium,
+weighed sixteen millions more of tons, or nearly twice as much as all
+the ships in the world could carry at a cargo each. It might fall in
+an hour, or it might fall in a day; but, occupy what time it might
+in falling, this rain is calculated to exert so much force--which is
+inconceivably great--in disturbing the equilibrium of the ocean. If
+all the water discharged by the Mississippi river during the year were
+taken up in one mighty measure, and cast into the ocean at one effort,
+it would not make a greater disturbance in the equilibrium of the
+sea than would the fall of rain supposed. And yet so gentle are the
+operations of nature, that movements so vast are unperceived.
+
+
+THE EQUATORIAL CLOUD-RING.
+
+In crossing the Equatorial Doldrums, the voyager passes a ring of
+clouds that encircles the earth, and is stretched around our planet
+to regulate the quantity of precipitation in the rain-belt beneath
+it; to preserve the due quantum of heat on the face of the earth; to
+adjust the winds; and send out for distribution to the four corners
+vapours in proper quantities, to make up to each river-basin, climate,
+and season, its quota of sunshine, cloud, and moisture. Like the
+balance-wheel of a well-constructed chronometer, this cloud-ring
+affords the grand atmospherical machine the most exquisitely arranged
+_self-compensation_. Nature herself has hung a thermometer under this
+cloud-belt that is more perfect than any that man can construct, and
+its indications are not to be mistaken.--_Maury._
+
+
+“THE EQUATORIAL DOLDRUMS”
+
+is another of these calm places. Besides being a region of calms and
+baffling winds, it is a region noted for its rains and clouds, which
+make it one of the most oppressive and disagreeable places at sea. The
+emigrant ships from Europe for Australia have to cross it. They are
+often baffled in it for two or three weeks; then the children and the
+passengers who are of delicate health suffer most. It is a frightful
+graveyard on the wayside to that golden land.
+
+
+BEAUTY OF THE DEW-DROP.
+
+The Dew-drop is familiar to every one from earliest infancy. Resting
+in luminous beads on the down of leaves, or pendent from the finest
+blades of grass, or threaded upon the floating lines of the gossamer,
+its “orient pearl” varies in size from the diameter of a small pea to
+the most minute atom that can be imagined to exist. Each of these, like
+the rain-drops, has the properties of reflecting and refracting light;
+hence, from so many minute prisms, the unfolded rays of the sun are
+sent up to the eye in colours of brilliancy similar to those of the
+rainbow. When the sunbeams traverse horizontally a very thickly-bedewed
+grass-plot, these colours arrange themselves so as to form an iris,
+or dew-bow; and if we select any one of these drops for observation,
+and steadily regard it while we gradually change our position, we
+shall find the prismatic colours follow each other in their regular
+order.--_Wells._
+
+
+FALL OF DEW IN ONE YEAR.
+
+The annual average quantity of Dew deposited in this country is
+estimated at a depth of about five inches, being about one-seventh
+of the mean quantity of moisture supposed to be received from the
+atmosphere all over Great Britain in the year; or about 22,161,337,355
+tons, taking the ton at 252 imperial gallons.--_Wells._
+
+
+GRADUATED SUPPLY OF DEW TO VEGETATION.
+
+Each of the different grasses draws from the atmosphere during the
+night a supply of dew to recruit its energies dependent upon its form
+and peculiar radiating power. Every flower has a power of radiation
+of its own, subject to changes during the day and night, and the
+deposition of moisture on it is regulated by the peculiar law which
+this radiating power obeys; and this power will be influenced by
+the aspect which the flower presents to the sky, unfolding to the
+contemplative mind the most beautiful example of creative wisdom.[39]
+
+
+WARMTH OF SNOW IN ARCTIC LATITUDES.
+
+The first warm Snows of August and September (says Dr. Kane), falling
+on a thickly-bleached carpet of grasses, heaths, and willows, enshrine
+the flowery growths which nestle round them in a non-conducting air
+chamber; and as each successive snow increases the thickness of the
+cover, we have, before the intense cold of winter sets in, a light
+cellular bed covered by drift, seven, eight, or ten feet deep, in which
+the plant retains its vitality. Dr. Kane has proved by experiments that
+the conducting power of the snow is proportioned to its compression
+by winds, rains, drifts, and congelation. The drifts that accumulate
+during nine months of the year are dispersed in well-defined layers
+of different density. We have first the warm cellular snows of fall,
+which surround the plant; next the finely-impacted snow-dust of winter;
+and above these the later humid deposits of spring. In the earlier
+summer, in the inclined slopes that face the sun, as the upper snow is
+melted and sinks upon the more compact layer below it is to a great
+extent arrested, and runs off like rain from a slope of clay. The plant
+reposes thus in its cellular bed, safe from the rush of waters, and
+protected from the nightly frosts by the icy roof above it.
+
+
+IMPURITY OF SNOW.
+
+It is believed that in ascending mountains difficult breathing is
+sooner felt upon snow than upon rock; and M. Boussingault, in his
+account of the ascent of Chimborazo, attributes this to the sensible
+deficiency of oxygen contained in the pores of the snow, which is
+exhaled when it melts. The fact that the air absorbed by snow is
+impure, was ascertained by De Saussure, and has been confirmed by
+Boussingault’s experiments.--_Quarterly Review_, No. 202.
+
+
+SNOW PHENOMENON.
+
+Professor Dove of Berlin relates, in illustration of the formation of
+clouds of Snow over plains situated at a distance from the cooling
+summits of mountains, that on one occasion a large company had gathered
+in a ballroom in Sweden. It was one of those icy starlight nights
+which in that country are so aptly called “iron nights.” The weather
+was clear and cold, and the ballroom was clear and warm; and the heat
+was so great, that several ladies fainted. An officer present tried to
+open a window; but it was frozen fast to the sill. As a last resort, he
+broke a pane of glass; the cold air rushed in, and it _snowed in the
+room_. A minute before all was clear; but the warm air of the room had
+sustained an amount of moisture in a transparent condition which it was
+not able to maintain when mixed with the colder air from without. The
+vapour was first condensed, and then frozen.
+
+
+ABSENCE OF SNOW IN SIBERIA.
+
+There is in Siberia, M. Ermann informs us, an _entire district_ in
+which during the winter the sky is constantly clear, and where a single
+particle of snow never falls.--_Arago._
+
+
+ACCURACY OF THE CHINESE AS OBSERVERS.
+
+The beautiful forms of snow-crystals have long since attracted Chinese
+observers; for from a remote period there has been met with in their
+conversation and books an axiomatic expression, to the effect that
+“snow-flakes are hexagonal,” showing the Chinese to be accurate
+observers of nature.
+
+
+PROTECTION AGAINST HAIL AND STORMS.
+
+Arago relates, that when, in 1847, two small agricultural districts
+of Bourgoyne had lost by Hail crops to the value of a million and a
+half of francs, certain of the proprietors went to consult him on the
+means of protecting them from like disasters. Resting on the hypothesis
+of the electric origin of hail, Arago suggested the discharge of
+the electricity of the clouds by means of balloons communicating by
+a metallic wire with the soil. This project was not carried out;
+but Arago persisted in believing in the effectiveness of the method
+proposed.
+
+  Arago, in his _Meteorological Essays_, inquires whether the firing
+  of cannon can dissipate storms. He cites several cases in its
+  favour, and others which seem to oppose it; but he concludes by
+  recommending it to his successors. Whilst Arago was propounding
+  these questions, a person not conversant with science, the poet
+  Méry, was collecting facts supporting the view, which he has
+  published in his _Paris Futur_. His attention was attracted to the
+  firing of cannon to dissipate storms in 1828, whilst an assistant
+  in the “Ecole de Tir” at Vincennes. Having observed that there was
+  never any rain in the morning of the exercise of firing, he waited
+  to examine military records, and found there, as he says, facts
+  which justified the expressions of “Le soleil d’Austerlitz,” “Le
+  soleil de juillet,” upon the morning of the Revolution of July;
+  and he concluded by proposing to construct around Paris twelve
+  towers of great height, which he calls “tours imbrifuges,” each
+  carrying 100 cannons, which should be discharged into the air on
+  the approach of a storm. About this time an incident occurred which
+  in nowise confirmed the truth of M. Méry’s theory. The 14th of
+  August was a fine day. On the 15th, the fête of the Empire, the
+  sun shone out, the cannon thundered all day long, fireworks and
+  illuminations were blazing from nine o’clock in the evening. Every
+  thing conspired to verify the hypothesis of M. Méry, and chase
+  away storms for a long time. But towards eleven in the evening
+  a torrent of rain burst upon Paris, in spite of the pretended
+  influence of the discharge of cannon, and gave an occasion for the
+  mobile Gallic mind to turn its attention in other directions.
+
+
+TERRIFIC HAILSTORM.
+
+Jansen describes, from the log-book of the _Rhijin_, Captain Brandligt,
+in the South-Indian Ocean (25° south latitude) a Hurricane, accompanied
+by Hail, by which several of the crew were made blind, others had their
+faces cut open, and those who were in the rigging had their clothes
+torn off them. The master of the ship compared the sea “to a hilly
+landscape in winter covered with snow.” Does it not appear as if the
+“treasures of the hail” were opened, which were “reserved against the
+time of trouble, against the day of battle and war”?
+
+
+HOW WATERSPOUTS ARE FORMED IN THE JAVA SEA.
+
+Among the small groups of islands in this sea, in the day and night
+thunderstorms, the combat of the clouds appears to make them more
+thirsty than ever. In tunnel form, when they can no longer quench their
+thirst from the surrounding atmosphere, they descend near the surface
+of the sea, and appear to lap the water directly up with their black
+mouths. They are not always accompanied by strong winds; frequently
+more than one is seen at a time, whereupon the clouds whence they
+proceed disperse, and the ends of the Waterspouts bending over finally
+causes them to break in the middle. They seldom last longer than five
+minutes. As they are going away, the bulbous tube, which is as palpable
+as that of a thermometer, becomes broader at the base; and little
+clouds, like steam from the pipe of a locomotive, are continually
+thrown off from the circumference of the spout, and gradually the water
+is released, and the cloud whence the spout came again closes its mouth.
+
+
+COLD IN HUDSON’S BAY.
+
+Mr. R. M. Ballantyne, in his journal of six years’ residence in the
+territories of the Hudson’s Bay Company, tells us, that for part of
+October there is sometimes a little warm, or rather thawy, weather; but
+after that, until the following April, the thermometer seldom rises
+to the freezing point. In the depth of winter, the thermometer falls
+from 30° to 40°, 45°, and even 49° _below zero_ of Fahrenheit. This
+intense cold is not, however, so much felt as one might suppose; for
+during its continuance the air is perfectly calm. Were the slightest
+breath of wind to rise when the thermometer stands so low, no man could
+show his face to it for a moment. Forty degrees below zero, and quite
+calm, is infinitely preferable to fifteen below, or thereabout, with
+a strong breeze of wind. Spirit of wine is, of course, the only thing
+that can be used in the thermometer; as mercury, were it exposed to
+such cold, would remain frozen nearly half the winter. Spirit never
+froze in any cold ever experienced at York Factory, unless when very
+much adulterated with water; and even then the spirit would remain
+liquid in the centre of the mass. Quicksilver easily freezes in this
+climate, and it has frequently been run into a bullet-mould, exposed to
+the cold air till frozen, and in this state rammed down a gun-barrel,
+and fired through a thick plank. The average cold may be set down at
+about 15° or 16° below zero, or 48° of frost. The houses at the Bay are
+built of wood, with double windows and doors. They are heated by large
+iron stoves, fed with wood; yet so intense is the cold, that when a
+stove has been in places red-hot, a basin of water in the room has been
+frozen solid.
+
+
+PURITY OF WENHAM-LAKE ICE.
+
+Professor Faraday attributes the purity of Wenham-Lake Ice to its being
+free from air-bubbles and from salts. The presence of the first makes
+it extremely difficult to succeed in making a lens of English ice which
+will concentrate the solar rays, and readily fire gunpowder; whereas
+nothing is easier than to perform this singular feat of igniting
+a combustible body by aid of a frozen mass if Wenham-Lake ice be
+employed. The absence of salts conduces greatly to the permanence of
+the ice; for where water is so frozen that the salts expelled are still
+contained in air-cavities and cracks, or form thin films between the
+layers of ice, these entangled salts cause the ice to melt at a lower
+temperature than 32°, and the liquefied portions give rise to streams
+and currents within the body of the ice which rapidly carry heat to the
+interior. The mass then goes on thawing within as well as without, and
+at temperatures below 32°; whereas pure, compact, Wenham-Lake ice can
+only thaw at 32°, and only on the outside of the mass.--_Sir Charles
+Lyell’s Second Visit to the United States._
+
+
+ARCTIC TEMPERATURES.
+
+Dr. Kane, in his Second Arctic Expedition, found the thermometers
+beginning to show unexampled temperature: they ranged from 60° to 70°
+below zero, and upon the taffrail of the brig 65°. The reduced mean of
+the best spirit-standards gave 67° or 99° below the freezing point of
+water. At these temperatures chloric ether became solid, and chloroform
+exhibited a granular pellicle on its surface. Spirit of naphtha froze
+at 54°, and the oil of turpentine was solid at 63° and 65°.
+
+
+DR. RAE’S ARCTIC EXPLORATIONS.
+
+The gold medal of the Royal Geographical Society was in 1852 most
+rightfully awarded to this indefatigable Arctic explorer. His survey of
+the inlet of Boothia, in 1848, was unique in its kind. In Repulse Bay
+he maintained his party on deer, principally shot by himself; and spent
+ten months of an Arctic winter in a hut of stones, with no other fuel
+than a kind of hay of the _Andromeda tetragona_. Thus he preserved his
+men to execute surveying journeys of 1000 miles in the spring. Later he
+travelled 300 miles on snow-shoes. In a spring journey over the ice,
+with a pound of fat daily for fuel, accompanied by two men only, and
+trusting solely for shelter to snow-houses, which he taught his men to
+build, he accomplished 1060 miles in thirty-nine days, or twenty-seven
+miles per day, including stoppages,--a feat never equalled in Arctic
+travelling. In the spring journey, and that which followed in the
+summer in boats, 1700 miles were traversed in eighty days. Dr. Rae’s
+greatest sufferings, he once remarked to Sir George Back, arose from
+his being obliged to sleep upon his frozen mocassins in order to thaw
+them for the morning’s use.
+
+
+PHENOMENA OF THE ARCTIC CLIMATE.
+
+Sir John Richardson, in his history of his Expedition to these regions,
+describes the power of the sun in a cloudless sky to have been so
+great, that he was glad to take shelter in the water while the crews
+were engaged on the portages; and he has never felt the direct rays of
+the sun so oppressive as on some occasions in the high latitudes. Sir
+John observes:
+
+  The rapid evaporation of both snow and ice in the winter and
+  spring, long before the action of the sun has produced the
+  slightest thaw or appearance of moisture, is evident by many
+  facts of daily occurrence. Thus when a shirt, after being washed,
+  is exposed in the open air to a temperature of from 40° to 50°
+  below zero, it is instantly rigidly frozen, and may be broken if
+  violently bent. If agitated when in this condition by a strong
+  wind, it makes a rustling noise like theatrical thunder.
+
+  In consequence of the extreme dryness of the atmosphere in winter,
+  most articles of English manufacture brought to Rupert’s Land are
+  shrivelled, bent, and broken. The handles of razors and knives,
+  combs, ivory scales, &c., kept in the warm room, are changed in
+  this way. The human body also becomes vividly electric from the
+  dryness of the skin. One cold night I rose from my bed, and was
+  going out to observe the thermometer, with no other clothing than
+  my flannel night-dress, when on my hand approaching the iron latch
+  of the door, a distinct spark was elicited. Friction of the skin at
+  almost all times in winter produced the electric odour.
+
+  Even at midwinter we had but three hours and a half of daylight.
+  On December 20th I required a candle to write at the window at ten
+  in the morning. The sun was absent ten days, and its place in the
+  heavens at noon was denoted by rays of light shooting into the sky
+  above the woods.
+
+  The moon in the long nights was a most beautiful object, that
+  satellite being constantly above the horizon for nearly a fortnight
+  together. Venus also shone with a brilliancy which is never
+  witnessed in a sky loaded with vapours; and, unless in snowy
+  weather, our nights were always enlivened by the beams of the
+  aurora.
+
+
+INTENSE HEAT AND COLD OF THE DESERT.
+
+Among crystalline bodies, rock-crystal, or silica, is the best
+conductor of heat. This fact accounts for the steadiness of temperature
+in one set district, and the extremes of Heat and Cold presented by
+day and night on such sandy wastes as the Sahara. The sand, which is
+for the most part silica, drinks-in the noon-day heat, and loses it by
+night just as speedily.
+
+The influence of the hot winds from the Sahara has been observed
+in vessels traversing the Atlantic at a distance of upwards of
+1100 geographical miles from the African shores, by the coating of
+impalpable dust upon the sails.
+
+
+TRANSPORTING POWER OF WINDS.
+
+The greatest example of their power is the _sand-flood_ of Africa,
+which, moving gradually eastward, has overwhelmed all the land capable
+of tillage west of the Nile, unless sheltered by high mountains, and
+threatens ultimately to obliterate the rich plain of Egypt.
+
+
+EXHILARATION IN ASCENDING MOUNTAINS.
+
+At all elevations of from 6000 to 11,000 feet, and not unfrequently
+for even 2000 feet more, the pedestrian enjoys a pleasurable feeling,
+imparted by the consciousness of existence, similar to that which is
+described as so fascinating by those who have become familiar with the
+desert-life of the East. The body seems lighter, the nervous power
+greater, the appetite is increased; and fatigue, though felt for a
+time, is removed by the shortest repose. Some travellers have described
+the sensation by the impression that they do not actually press the
+ground, but that the blade of a knife could be inserted between the
+sole of the foot and the mountain top.--_Quarterly Review_, No. 202.
+
+
+TO TELL THE APPROACH OF STORMS.
+
+The proximity of Storms has been ascertained with accuracy by
+various indications of the electrical state of the atmosphere. Thus
+Professor Scott, of Sandhurst College, observed in Shetland that
+drinking-glasses, placed in an inverted position upon a shelf in a
+cupboard on the ground-floor of Belmont House, occasionally emitted
+sounds as if they were tapped with a knife, or raised a little and
+then let fall on the shelf. These sounds preceded wind; and when they
+occurred, boats and vessels were immediately secured. The strength of
+the sound is said to be proportioned to the tempest that follows.
+
+
+REVOLVING STORMS.
+
+By the conjoint labours of Mr. Redfield, Colonel Reid, and Mr.
+Piddington, on the origin and nature of hurricanes, typhoons, or
+revolving storms, the following important results have been obtained.
+Their existence in moderate latitudes on both sides the equator; their
+absence in the immediate neighbourhood of the equatorial regions; and
+the fact, that while in the northern latitudes these storms revolve
+in a direction contrary to the hands of a watch the face of which is
+placed upwards, in the southern latitudes they rotate in the opposite
+direction,--are shown to be so many additions to the long chain of
+evidence by which the rotation of the earth as a physical fact is
+demonstrated.
+
+
+IMPETUS OF A STORM.
+
+Captain Sir S. Brown estimates, from experiments made by him at the
+extremity of the Brighton-Chain Pier in a heavy south-west gale, that
+the waves impinge on a cylindrical surface one foot high and one foot
+in diameter with a force equal to eighty pounds, to which must be added
+that of the wind, which in a violent storm exerts a pressure of forty
+pounds. He computed the collective impetus of the waves on the lower
+part of a lighthouse proposed to be built on the Wolf Rock (exposed
+to the most violent storms of the Atlantic), of the surf on the upper
+part, and of the wind on the whole, to be equal to 100 tons.
+
+
+HOW TO MAKE A STORM-GLASS.
+
+This instrument consists of a glass tube, sealed at one end, and
+furnished with a brass cap at the other end, through which the air
+is admitted by a very small aperture. Nearly fill the tube with the
+following solution: camphor, 2½ drams; nitrate of potash, 38 grains;
+muriate of ammonia, 38 grains; water, 9 drams; rectified spirit,
+9 drams. Dissolve with heat. At the ordinary temperature of the
+atmosphere, plumose crystals are formed. On the approach of stormy
+weather, these crystals appear compressed into a compact mass at the
+bottom of the tube; while during fine weather they assume their plumose
+character, and extend a considerable way up the glass. These results
+depend upon the condition of the air, but they are not considered to
+afford any reliable indication of approaching weather.
+
+
+SPLENDOUR OF THE AURORA BOREALIS.
+
+Humboldt thus beautifully describes this phenomenon:
+
+  The intensity of this light is at times so great, that Lowenörn
+  (on June 29, 1786) recognised its coruscation in bright sunshine.
+  Motion renders the phenomenon more visible. Round the point in
+  the vault of heaven which corresponds to the direction of the
+  inclination of the needle the beams unite together to form the
+  so-called corona, the crown of the Northern Light, which encircles
+  the summit of the heavenly canopy with a milder radiance and
+  unflickering emanations of light. It is only in rare instances that
+  a perfect crown or circle is formed; but on its completion, the
+  phenomenon has invariably reached its maximum, and the radiations
+  become less frequent, shorter, and more colourless. The crown, and
+  the luminous arches break up; and the whole vault of heaven becomes
+  covered with irregularly scattered, broad, faint, almost ashy-gray,
+  luminous, immovable patches, which in their turn disappear, leaving
+  nothing but a trace of a dark smoke-like segment on the horizon.
+  There often remains nothing of the whole spectacle but a white
+  delicate cloud with feathery edges, or divided at equal distances
+  into small roundish groups like cirro-cumuli.--_Cosmos_, vol. i.
+
+Among many theories of this phenomenon is that of Lieutenant Hooper,
+R.N., who has stated to the British Association that he believes “the
+Aurora Borealis to be no more nor less than the moisture in some
+shape (whether dew or vapour, liquid or frozen), illuminated by the
+heavenly bodies, either directly, or reflecting their rays from the
+frozen masses around the Pole, or even from the immediately proximate
+snow-clad earth.”
+
+
+VARIETIES OF LIGHTNING.
+
+According to Arago’s investigations, the evolution of Lightning is of
+three kinds: zigzag, and sharply defined at the edges; in sheets of
+light, illuminating a whole cloud, which seems to open and reveal the
+light within it; and in the form of fire-balls. The duration of the
+first two kinds scarcely continues the thousandth part of a second; but
+the globular lightning moves much more slowly, remaining visible for
+several seconds.
+
+
+WHAT IS SHEET-LIGHTNING?
+
+This electric phenomenon is unaccompanied by thunder, or too distant to
+be heard: when it appears, the whole sky, but particularly the horizon,
+is suddenly illuminated with a flickering flash. Philosophers differ
+much as to its cause. Matteucci supposes it to be produced either
+during evaporation, or evolved (according to Pouillet’s theory) in the
+process of vegetation; or generated by chemical action in the great
+laboratory of nature, the earth, and accumulated in the lower strata of
+the air in consequence of the ground being an imperfect conductor.
+
+  Arago and Kamtz, however, consider sheet-lightning as _reflections
+  of distant thunderstorms_. Saussure observed sheet-lightning in the
+  direction of Geneva, from the Hospice du Grimsel, on the 10th and
+  11th of July 1783; while at the same time a terrific thunderstorm
+  raged at Geneva. Howard, from Tottenham, near London, on July 31,
+  1813, saw sheet-lightning towards the south-east, while the sky was
+  bespangled with stars, not a cloud floating in the air; at the same
+  time a thunderstorm raged at Hastings, and in France from Calais
+  to Dunkirk. Arago supports his opinion, that the phenomenon is
+  _reflected lightning_, by the following illustration: In 1803, when
+  observations were being made for determining the longitude, M. de
+  Zach, on the Brocken, used a few ounces of gunpowder as a signal,
+  the flash of which was visible from the Klenlenberg, sixty leagues
+  off, although these mountains are invisible from each other.
+
+
+PRODUCTION OF LIGHTNING BY RAIN.
+
+A sudden gust of rain is almost sure to succeed a violent detonation
+immediately overhead. Mr. Birt, the meteorologist, asks: Is this rain a
+_cause_ or _consequence_ of the electric discharge? To this he replies:
+
+  In the sudden agglomeration of many minute and feebly electrified
+  globules into one rain-drop, the quantity of electricity is
+  increased in a greater proportion than the surface over which
+  (according to the laws of electric distribution) it is spread. By
+  tension, therefore, it is increased, and may attain the point when
+  it is capable of separating from the _drop_ to seek the surface of
+  the _cloud_, or of the newly-formed descending body of rain, which,
+  under such circumstances, may be regarded as a conducting medium.
+  Arrived at this surface, the tension, for the same reason, becomes
+  enormous, and a flash escapes. This theory Mr. Birt has confirmed
+  by observation of rain in thunderstorms.
+
+
+SERVICE OF LIGHTNING-CONDUCTORS.
+
+Sir David Brewster relates a remarkable instance of a tree in
+Clandeboye Park, in a thick mass of wood, and _not the tallest of the
+group_, being struck by lightning, which passed down the trunk into
+the ground, rending the tree asunder. This shows that an object may be
+struck by lightning in a locality where there are numerous conducting
+points more elevated than itself; and at the same time proves that
+lightning cannot be diverted from its course by lofty isolated
+conductors, but that the protection of buildings from this species
+of meteor can only be effected by conductors stretching out in all
+directions.
+
+Professor Silliman states, that lightning-rods cannot be relied upon
+unless they reach the earth where it is permanently wet; and that the
+best security is afforded by carrying the rod, or some good metallic
+conductor duly connected with it, to the water in the well, or to some
+other water that never fails. The professor’s house, it seems, was
+struck; but his lightning-rods were not more than two or three inches
+in the ground, and were therefore virtually of no avail in protecting
+the building.
+
+
+ANCIENT LIGHTNING-CONDUCTOR.
+
+Humboldt informs us, that “the most important ancient notice of the
+relations between lightning and conducting metals is that of Ctesias,
+in his _Indica_, cap. iv. p. 190. He possessed two iron swords,
+presents from the king Artaxerxes Mnemon and from his mother Parasytis,
+which, when planted in the earth, averted clouds, hail, and _strokes of
+lightning_. He had himself seen the operation, for the king had twice
+made the experiment before his eyes.”--_Cosmos_, vol. ii.
+
+
+THE TEMPLE OF JERUSALEM PROTECTED FROM LIGHTNING.
+
+We do not learn, either from the Bible or Josephus, that the Temple
+at Jerusalem was ever struck by Lightning during an interval of more
+than a thousand years, from the time of Solomon to the year 70;
+although, from its situation, it was completely exposed to the violent
+thunderstorms of Palestine.
+
+By a fortuitous circumstance, the Temple was crowned with
+lightning-conductors similar to those which we now employ, and which
+we owe to Franklin’s discovery. The roof, constructed in what we call
+the Italian manner, and covered with boards of cedar, having a thick
+coating of gold, was garnished from end to end with long pointed and
+gilt iron or steel lances, which, Josephus says, were intended to
+prevent birds from roosting on the roof and soiling it. The walls
+were overlaid throughout with wood, thickly gilt. Lastly, there
+were in the courts of the Temple cisterns, into which the rain from
+the roof was conducted by _metallic pipes_. We have here both the
+lightning-rods and a means of conduction so abundant, that Lichtenberg
+is quite right in saying that many of the present apparatuses are far
+from offering in their construction so satisfactory a combination of
+circumstances.--_Abridged from Arago’s Meteorological Essays._
+
+
+HOW ST. PAUL’S CATHEDRAL IS PROTECTED FROM LIGHTNING.
+
+In March 1769, the Dean and Chapter of St. Paul’s addressed a letter
+to the Royal Society, requesting their opinion as to the best and most
+effectual method of fixing electrical conductors on the cathedral. A
+committee was formed for the purpose, and Benjamin Franklin was one of
+the members; their report was made, and the conductors were fixed as
+follows:
+
+  The seven iron scrolls supporting the ball and cross are connected
+  with other rods (used merely as conductors), which unite them
+  with several large bars, descending obliquely to the stone-work
+  of the lantern, and connected by an iron ring with four other
+  iron bars to the lead covering of the great cupola, a distance
+  of forty-eight feet; thence the communication is continued by
+  the rain-water pipes to the lead-covered roof, and thence by lead
+  water-pipes which pass into the earth; thus completing the entire
+  communication from the cross to the ground, partly through iron,
+  and partly through lead. On the clock-tower a bar of iron connects
+  the pine-apple at the top with the iron staircase, and thence with
+  the lead on the roof of the church. The bell-tower is similarly
+  protected. By these means the metal used in the building is made
+  available as conductors; the metal employed merely for that purpose
+  being exceedingly small in quantity.--_Curiosities of London._
+
+
+VARIOUS EFFECTS OF LIGHTNING.
+
+Dr. Hibbert tells us that upon the western coast of Scotland and
+Ireland, Lightning coöperates with the violence of the storm in
+shattering solid rocks, and heaping them in piles of enormous
+fragments, both on dry land and beneath the water.
+
+Euler informs us, in his _Letters to a German Princess_, that he
+corresponded with a Moravian priest named Divisch, who assured him
+that he had averted during a whole summer every thunderstorm which
+threatened his own habitation and the neighbourhood, by means of a
+machine constructed upon the principles of electricity; that the
+machinery sensibly attracted the clouds, and constrained them to
+descend quietly in a distillation, without any but a very distant
+thunderclap. Euler assures us that “the fact is undoubted, and
+confirmed by irresistible proof.”
+
+About the year 1811, in the village of Phillipsthal, in Eastern
+Prussia, an attempt was made to split an immense stone into a multitude
+of pieces by means of lightning. A bar of iron, in the form of a
+conductor, was previously fixed to the stone; and the experiment was
+attended with complete success; for during the very first thunderstorm
+the lightning burst the stone without displacing it.
+
+The celebrated Duhamel du Monceau says, that lightning, unaccompanied
+by thunder, wind, or rain, has the property of breaking oat-stalks. The
+farmers are acquainted with this effect, and say that the lightning
+breaks down the oats. This is a well-received opinion with the farmers
+in Devonshire.
+
+Lightning has in some cases the property of reducing solid bodies to
+ashes, or to pulverisation,--even the human body,--without there being
+any signs of heat. The effects of lightning on paralysis are very
+remarkable, in some cases curing, in others causing, that disease.
+
+The returning stroke of lightning is well known to be due to the
+restoration of the natural electric state, after it has been disturbed
+by induction.
+
+
+A THUNDERSTORM SEEN FROM A BALLOON.
+
+Mr. John West, the American aeronaut, in his observations made during
+his numerous ascents, describes a storm viewed from above the clouds
+to have the appearance of ebullition. The bulging upper surface of the
+cloud resembles a vast sea of boiling and upheaving snow; the noise
+of the falling rain is like that of a waterfall over a precipice; the
+thunder above the cloud is not loud, and the flashes of lightning
+appear like streaks of intensely white fire on a surface of white
+vapour. He thus describes a side view of a storm which he witnessed
+June 3, 1852, in his balloon excursion from Portsmouth, Ohio:
+
+  Although the sun was shining on me, the rain and small hail were
+  rattling on the balloon. A rainbow, or prismatically-coloured arch
+  or horse-shoe, was reflected against the sun; and as the point of
+  observation changed laterally and perpendicularly, the perspective
+  of this golden grotto changed its hues and forms. Above and behind
+  this arch was going on the most terrific thunder; but no zigzag
+  lightning was perceptible, only bright flashes, like explosions
+  of “Roman candles” in fireworks. Occasionally there was a zigzag
+  explosion in the cloud immediately below, the thunder sounding like
+  a _feu-de-joie_ of a rifle-corps. Then an orange-coloured wave of
+  light seemed to fall from the upper to the lower cloud; this was
+  “still-lightning.” Meanwhile intense electrical action was going
+  on _in the balloon_, such as expansion, tremulous tension, lifting
+  papers ten feet out of the car below the balloon and then dropping
+  them, &c. The close view of this Ohio storm was truly sublime; its
+  rushing noise almost appalling.
+
+Ascending from the earth with a balloon, in the rear of a storm, and
+mounted up a thousand feet above it, the balloon will soon override the
+storm, and may descend in advance of it. Mr. West has experienced this
+several times.
+
+
+REMARKABLE AERONAUTIC VOYAGE.
+
+Mr. Sadler, the celebrated aeronaut, ascended on one occasion in a
+balloon from Dublin, and was wafted across the Irish Channel; when,
+on his approach to the Welsh coast, the balloon descended nearly to
+the surface of the sea. By this time the sun was set, and the shades
+of evening began to close in. He threw out nearly all his ballast,
+and suddenly sprang upward to a great height; and by so doing brought
+his horizon to _dip_ below the sun, producing the whole phenomenon
+of a western sunrise. Subsequently descending in Wales, he of course
+witnessed a second sunset on the same evening.--_Sir John Herschel’s
+Outlines of Astronomy._
+
+
+
+
+Physical Geography of the Sea.[40]
+
+
+CLIMATES OF THE SEA.
+
+The fauna and flora of the Sea are as much the creatures of Climate,
+and are as dependent for their well-being upon temperature, as are the
+fauna and flora of the dry land. Were it not so, we should find the
+fish and the algæ, the marine insect and the coral, distributed equally
+and alike in all parts of the ocean; the polar whale would delight in
+the torrid zone; and the habitat of the pearl oyster would be also
+under the iceberg, or in frigid waters colder than the melting ice.
+
+
+THE CIRCULATION OF THE SEA.
+
+The coral islands, reefs, and beds with which the Pacific Ocean is
+studded and garnished, were built up of materials which a certain
+kind of insect quarried from the sea-water. The currents of the sea
+ministered to this little insect; they were its _hod-carriers_. When
+fresh supplies of solid matter were wanted for the coral rock upon
+which the foundations of the Polynesian Islands were laid, these
+hod-carriers brought them in unfailing streams of sea-water, loaded
+with food and building-materials for the coralline: the obedient
+currents thread the widest and the deepest sea. Now we know that
+its adaptations are suited to all the wants of every one of its
+inhabitants,--to the wants of the coral insect as well as those of the
+whale. Hence _we know_ that the sea has its system of circulation: for
+it transports materials for the coral rock from one part of the world
+to another; its currents receive them from rivers, and hand them over
+to the little mason for the structure of the most stupendous works of
+solid masonry that man has ever seen--the coral islands of the sea.
+
+
+TEMPERATURE OF THE SEA.
+
+Between the hottest hour of the day and the coldest hour of the night
+there is frequently a change of four degrees in the Temperature of the
+Sea. Taking one-fifth of the Atlantic Ocean for the scene of operation,
+and the difference of four degrees to extend only ten feet below
+the surface, the total and absolute change made in such a mass of
+sea-water, by altering its temperature two degrees, is equivalent to a
+change in its volume of 390,000,000 cubic feet.
+
+
+TRANSPARENCY OF THE OCEAN.
+
+Captain Glynn, U.S.N., has made some interesting observations, ranging
+over 200° of latitude, in different oceans, in very high latitudes,
+and near the equator. His apparatus was simple: a common white
+dinner-plate, slung so as to lie in the water horizontally, and sunk
+by an iron pot with a line. Numbering the fathoms at which the plate
+was visible below the surface, Captain Glynn saw it on two occasions,
+at the maximum, twenty-five fathoms (150 feet) deep; the water was
+extraordinarily clear, and to lie in the boat and look down was like
+looking down from the mast-head; and the objects were clearly defined
+to a great depth.
+
+
+THE BASIN OF THE ATLANTIC.
+
+In its entire length, the basin of this sea is a long trough,
+separating the Old World from the New, and extending probably from pole
+to pole.
+
+This ocean-furrow was scored into the solid crust of our planet by the
+Almighty hand, that there the waters which “he called seas” might be
+gathered together so as to “let the dry land appear,” and fit the earth
+for the habitation of man.
+
+From the top of Chimborazo to the bottom of the Atlantic, at the
+deepest place yet recognised by the plummet in the North Atlantic, the
+distance in a vertical line is nine miles.
+
+Could the waters of the Atlantic be drawn off, so as to expose to
+view this great sea-gash, which separates continents, and extends
+from the Arctic to the Antarctic, it would present a scene the most
+grand, rugged, and imposing. The very ribs of the solid earth, with
+the foundations of the sea, would be brought to light; and we should
+have presented to us at one view, in the empty cradle of the ocean,
+“a thousand fearful wrecks,” with that dreadful array of dead men’s
+skulls, great anchors, heaps of pearls and inestimable stones, which,
+in the dreamer’s eye, lie scattered on the bottom of the sea, making it
+hideous with sights of ugly death.
+
+
+GALES OF THE ATLANTIC.
+
+Lieutenant Maury has, in a series of charts of the North and South
+Atlantic, exhibited, by means of colours, the prevalence of Gales
+over the more stormy parts of the oceans for each month in the year.
+One colour shows the region in which there is a gale every six days;
+another colour every six to ten days; another every ten to fourteen
+days: and there is a separate chart for each month and each ocean.
+
+
+SOLITUDE AT SEA.
+
+Between Humboldt’s Current of Peru and the great equatorial flow, there
+is “a desolate region,” rarely visited by the whale, either sperm or
+right. Formerly this part of the ocean was seldom whitened by the sails
+of a ship, or enlivened by the presence of man. Neither the industrial
+pursuits of the sea nor the highways of commerce called him into it.
+Now and then a roving cruiser or an enterprising whalesman passed that
+way; but to all else it was an unfrequented part of the ocean, and so
+remained until the gold-fields of Australia and the guano islands of
+Peru made it a thoroughfare. All vessels bound from Australia to South
+America now pass through it; and in the journals of some of them it
+is described as a region almost void of the signs of life in both sea
+and air. In the South-Pacific Ocean especially, where there is such a
+wide expanse of water, sea-birds often exhibit a companionship with a
+vessel, and will follow and keep company with it through storm and calm
+for weeks together. Even the albatross and Cape pigeon, that delight
+in the stormy regions of Cape Horn and the inhospitable climates of
+the Antarctic regions, not unfrequently accompany vessels into the
+perpetual summer of the tropics. The sea-birds that join the ship as
+she clears Australia will, it is said, follow her to this region, and
+then disappear. Even the chirp of the stormy petrel ceases to be heard
+here, and the sea itself is said to be singularly barren of “moving
+creatures that have life.”
+
+
+BOTTLES AND CURRENTS AT SEA.
+
+Seafaring people often throw a bottle overboard, with a paper
+stating the time and place at which it is done. In the absence of
+other information as to Currents, that afforded by these mute little
+navigators is of great value. They leave no track behind them, it is
+true, and their routes cannot be ascertained; but knowing where they
+are cast, and seeing where they are found, some idea may be formed as
+to their course. Straight lines may at least be drawn, showing the
+shortest distance from the beginning to the end of their voyage, with
+the time elapsed. Admiral Beechey has prepared a chart, representing,
+in this way, the tracks of more than 100 bottles. From this it appears
+that the waters from every quarter of the Atlantic tend towards the
+Gulf of Mexico and its stream. Bottles cast into the sea midway between
+the Old and the New Worlds, near the coasts of Europe, Africa, and
+America at the extreme north or farthest south, have been found either
+in the West Indies, or the British Isles, or within the well-known
+range of Gulf-Stream waters.
+
+
+“THE HORSE LATITUDES”
+
+are the belts of calms and light airs which border the polar edge of
+the north-east trade-winds. They are so called from the circumstance
+that vessels formerly bound from New England to the West Indies, with a
+deck-load of horses, were often so delayed in this calm belt of Cancer,
+that, from the want of water for their animals, they were compelled to
+throw a portion of them overboard.
+
+
+“WHITE WATER” AND LUMINOUS ANIMALS AT SEA.
+
+Captain Kingman, of the American clipper-ship _Shooting Star_, in lat.
+8° 46′ S., long. 105° 30′ E., describes a patch of _white water_,
+about twenty-three miles in length, making the whole ocean appear like
+a plain covered with snow. He filled a 60-gallon tub with the water,
+and found it to contain small luminous particles seeming to be alive
+with worms and insects, resembling a grand display of rockets and
+serpents seen at a great distance in a dark night; some of the serpents
+appearing to be six inches in length, and very luminous. On being taken
+up, they emitted light until brought within a few feet of a lamp, when
+nothing was visible; but by aid of a sextant’s magnifier they could
+be plainly seen--a jelly-like substance, without colour. A specimen
+two inches long was visible to the naked eye; it was about the size
+of a large hair, and tapered at the ends. By bringing one end within
+about one-fourth of an inch of a lighted lamp, the flame was attracted
+towards it, and burned with a red light; the substance crisped in
+burning, something like hair, or appeared of a red heat before being
+consumed. In a glass of the water there were several small round
+substances (say 1/16th of an inch in diameter) which had the power of
+expanding and contracting; when expanded, the outer rim appeared like a
+circular saw, the teeth turned inward.
+
+The scene from the clipper’s deck was one of awful grandeur: the sea
+having turned to phosphorus, and the heavens being hung in blackness,
+and the stars going out, seemed to indicate that all nature was
+preparing for that last grand conflagration which we are taught to
+believe will annihilate this material world.
+
+
+INVENTION OF THE LOG.
+
+Long before the introduction of the Log, hour-glasses were used to
+tell the distance in sailing. Columbus, Juan de la Cosa, Sebastian
+Cabot, and Vasco de Gama, were not acquainted with the Log and its mode
+of application; and they estimated the ship’s speed merely by the eye,
+while they found the distance they had made by the running-down of the
+sand in the _ampotellas_, or hour-glasses. The Log for the measurement
+of the distance traversed is stated by writers on navigation not to
+have been invented until the end of the sixteenth or the beginning of
+the seventeenth century (see _Encyclopædia Britannica_, 7th edition,
+1842). The precise date is not known; but it is certain that Pigafetta,
+the companion of Magellan, speaks, in 1521, of the Log as a well-known
+means of finding the course passed over. Navarete places the use of the
+log-line in English ships in 1577.
+
+
+LIFE OF THE SEA-DEEPS.
+
+The ocean teems with life, we know. Of the four elements of the old
+philosophers,--fire, earth, air, and water,--perhaps the sea most of
+all abounds with living creatures. The space occupied on the surface
+of our planet by the different families of animals and their remains
+is inversely as the size of the individual; the smaller the animal,
+generally speaking, the greater the space occupied by his remains.
+Take the elephant and his remains, and a microscopic animal and his,
+and compare them; the contrast as to space occupied is as striking as
+that of the coral reef or island with the dimensions of the whale. The
+graveyard that would hold the corallines, is larger than the graveyard
+that would hold the elephants.
+
+
+DEPTHS OF OCEAN AND AIR UNKNOWN.
+
+At some few places under the tropics, no bottom has been found with
+soundings of 26,000 feet, or more than four miles; whilst in the air,
+if, according to Wollaston, we may assume that it has a limit from
+which waves of sound may be reverberated, the phenomenon of twilight
+would incline us to assume a height at least nine times as great. The
+aerial ocean rests partly on the solid earth, whose mountain-chains and
+elevated plateaus rise like green wooded shoals, and partly on the sea,
+whose surface forms a moving base, on which rest the lower, denser, and
+more saturated strata of air.--_Humboldt’s Cosmos_, vol. i.
+
+The old Alexandrian mathematicians, on the testimony of Plutarch,
+believed the depth of the sea to depend on the height of the mountains.
+Mr. W. Darling has propounded to the British Association the theory,
+that as the sea covers three times the area of the land, so it is
+reasonable to suppose that the depth of the ocean, and that for a
+large portion, is three times as great as the height of the highest
+mountain. Recent soundings show depths in the sea much greater than any
+elevations on the surface of the earth; for a line has been veered to
+the extent of seven miles.--_Dr. Scoresby._
+
+
+GREATEST ASCERTAINED DEPTH OF THE SEA.
+
+In the dynamical theory of the tides, the ratio of the effects of the
+sun and moon depends, not only on the masses, distances, and periodic
+times of the two luminaries, but also on the Depth of the Sea; and
+this, accordingly, may be computed when the other quantities are known.
+In this manner Professor Haughton has deduced, from the solar and lunar
+coefficients of the diurnal tide, a mean depth of 5·12 miles; a result
+which accords in a remarkable manner with that inferred from the ratio
+of the semi-diurnal co-efficients as obtained by Laplace from the
+Brest observations. Professor Hennessey states, that from what is now
+known regarding the depth of the ocean, the continents would appear as
+plateaus elevated above the oceanic depressions to an amount which,
+although small compared to the earth’s radius, would be considerable
+when compared to its outswelling at the equator and its flattening
+towards the poles; and the surface thus presented would be the true
+surface of the earth.
+
+The greatest depths at which the bottom of the sea has been reached
+with the plummet are in the North-Atlantic Ocean; and the places where
+it has been fathomed (by the United-States deep-sea sounding apparatus)
+do not show it to be deeper than 25,000 feet = 4 miles, 1293 yards, 1
+foot. The deepest place in this ocean is probably between the parallels
+of 35° and 40° north latitude, and immediately to the southward of the
+Grand Banks of Newfoundland.
+
+  It appears that, with one exception, the bottom of the
+  North-Atlantic Ocean, as far as examined, from the depth of about
+  sixty fathoms to that of more than two miles (2000 fathoms), is
+  literally nothing but a mass of microscopic shells. Not one of
+  the animalcules from these shells has been found living in the
+  surface-waters, nor in shallow water along the shore. Hence arises
+  the question, Do they live on the bottom, at the immense depths
+  where the shells are found; or are they borne by submarine currents
+  from their real habitat?
+
+
+RELATIVE LEVELS OF THE RED SEA AND MEDITERRANEAN.
+
+The French engineers, at the beginning of the present century, came
+to the conclusion that the Red Sea was about thirty feet above the
+Mediterranean: but the observations of Mr. Robert Stephenson, the
+English engineer, at Suez; of M. Negretti, the Austrian, at Tineh,
+near the ancient Pelusium; and the levellings of Messrs. Talabat,
+Bourdaloue, and their assistants between the two seas;--have proved
+that the low-water mark of ordinary tides at Suez and Tineh is very
+nearly on the same levels, the difference being that at Suez it is
+rather more than one inch lower.--_Leonard Horner_; _Proceedings of the
+Royal Society_, 1855.
+
+
+THE DEPTH OF THE MEDITERRANEAN.
+
+Soundings made in the Mediterranean suffice to indicate depths equal
+to the average height of the mountains girding round this great basin;
+and, if one particular experiment may be credited, reaching even to
+15,000 feet--an equivalent to the elevation of the highest Alps. This
+sounding was made about ninety miles east of Malta. Between Cyprus and
+Egypt, 6000 feet of line had been let down without reaching the bottom.
+Other deep soundings have been made in other places with similar
+results. In the lines of sea between Egypt and the Archipelago, it is
+stated that one sounding made by the _Tartarus_ between Alexandria
+and Rhodes reached bottom at the depth of 9900 feet; another, between
+Alexandria and Candia, gave a depth of 300 feet beyond this. These
+single soundings, indeed, whether of ocean or sea, are always open to
+the certainty that greater as well as lesser depths must exist, to
+which no line has ever been sunk; a case coming under that general law
+of probabilities so largely applicable in every part of physics. In the
+Mediterranean especially, which has so many aspects of a sunken basin,
+there may be abysses of depth here and there which no plummet is ever
+destined to reach.--_Edinburgh Review._
+
+
+COLOUR OF THE RED SEA.
+
+M. Ehrenberg, while navigating the Red Sea, observed that the red
+colour of its waters was owing to enormous quantities of a new animal,
+which has received the name of _oscillatoria rubescens_, and which
+seems to be the same with what Haller has described as a _purple
+conferva_ swimming in water; yet Dr. Bonar, in his work entitled _The
+Desert of Sinai_, records:
+
+  Blue I have called the sea; yet not strictly so, save in the far
+  distance. It is neither a _red_ nor a _blue_ sea, but emphatically
+  green,--yes, green, of the most brilliant kind I ever saw. This is
+  produced by the immense tracts of shallow water, with yellow sand
+  beneath, which always gives this green to the sea, even in the
+  absence of verdure on the shore or sea-weeds beneath. The _blue_ of
+  the sky and the _yellow_ of the sands meeting and intermingling in
+  the water, form the _green_ of the sea; the water being the medium
+  in which the mixing or fusing of the colours takes place.
+
+
+WHAT IS SEA-MILK?
+
+The phenomena with this name and that of “Squid” are occasioned by the
+presence of phosphorescent animalcules. They are especially produced
+in the intertropical seas, and they appear to be chiefly abundant
+in the Gulf of Guinea and in the Arabian Gulf. In the latter, the
+phenomenon was known to the ancients more than a century before the
+Christian era, as may be seen from a curious passage from the geography
+of Agatharcides: “Along this country (the coast of Arabia) the sea
+has a white aspect like a river: the cause of this phenomenon is a
+subject of astonishment to us.” M. Quatrefages has discovered that the
+_Noctilucæ_ which produce this phenomenon do not always give out clear
+and brilliant sparks, but that under certain circumstances this light
+is replaced by a steady clearness, which gives in these animalcules a
+white colour. The waters in which they have been observed do not change
+their place to any sensible degree.
+
+
+THE BOTTOM OF THE SEA A BURIAL-PLACE.
+
+Among the minute shells which have been fished up from the great
+telegraphic plateau at the bottom of the sea between Newfoundland and
+Ireland, the microscope has failed to detect a single particle of sand
+or gravel; and the inference is, that there, if any where, the waters
+of the sea are at rest. There is not motion enough there to abrade
+these very delicate organisms, nor current enough to sweep them about
+and mix them up with a grain of the finest sand, nor the smallest
+particle of gravel from the loose beds of _débris_ that here and there
+strew the bottom of the sea. The animalculæ probably do not live or die
+there. They would have had no light there; and, if they lived there,
+their frail textures would be subjected in their growth to a pressure
+upon them of a column of water 12,000 feet high, equal to the weight of
+400 atmospheres. They probably live and sport near the surface, where
+they can feel the genial influence of both light and heat, and are
+buried in the lichen caves below after death.
+
+It is now suggested, that henceforward we should view the surface of
+the sea as a nursery teeming with nascent organisms, and its depths as
+the cemetery for families of living creatures that outnumber the sands
+on the sea-shore for multitude.
+
+Where there is a nursery, hard by there will be found also a
+graveyard,--such is the condition of the animal world. But it never
+occurred to us before to consider the surface of the sea as one
+wide nursery, its every ripple as a cradle, and its bottom one vast
+burial-place.--_Lieut. Maury._
+
+
+WHY IS THE SEA SALT?
+
+It has been replied, In order to preserve it in a state of purity;
+which is, however, untenable, mainly from the fact that organic
+impurities in a vast body of moving water, whether fresh or salt,
+become rapidly lost, so as apparently to have called forth a special
+agency to arrest the total organised matter in its final oscillation
+between the organic and inorganic worlds. Thus countless hosts of
+microscopic creatures swarm in most waters, their principal function
+being, as Professor Owen surmises, to feed upon and thus restore to
+the living chain the almost unorganised matter of various zones. These
+creatures preying upon one another, and being preyed upon by others
+in their turn, the circulation of organic matter is kept up. If we
+do not adopt this view, we must at least look upon the Infusoria and
+Foraminifera as scavenger agents to prevent an undue accumulation
+of decaying matter; and thus the salt condition of the sea is not a
+necessity.
+
+Nor is the amount of saline matter in the sea sufficient to arrest
+decomposition. That the sea is salt to render it of greater density,
+and by lowering its freezing point to preserve it from congelation to
+within a shorter distance of the poles, though admissible, scarcely
+meets the entire solution of the question. The freezing point of
+sea-water, for instance, is only 3½° F. lower than that of fresh water;
+hence, with the present distribution of land and sea--and still less,
+probably, with that which obtained in former geological epochs--no very
+important effects would have resulted had the ocean been fresh instead
+of salt.
+
+Now Professor Chapman, of Toronto, suggests that the salt condition of
+the sea is mainly intended to regulate evaporation, and to prevent an
+undue excess of that phenomenon; saturated solutions evaporating more
+slowly than weak ones, and these latter more slowly again than pure
+water.
+
+Here, then, we have a self-adjusting phenomenon and admirable
+contrivance in the balance of forces. If from any temporary cause there
+be an unusual amount of saline matter in the sea, evaporation goes on
+the more and more slowly; and, on the other hand, if this proportion
+be reduced by the addition of fresh water in undue excess, the
+evaporating power is the more and more increased--thus aiding time, in
+either instance, to restore the balance. The perfect system of oceanic
+circulation may be ascribed, in a great degree at least, if not wholly,
+to the effect produced by the salts of the sea upon the mobility and
+circulation of its waters.
+
+Now this is an office which the sea performs in the economy of the
+universe by virtue of its saltness, and which it could not perform were
+its waters altogether fresh. And thus philosophers have a clue placed
+in their hands which will probably guide to one of the many hidden
+reasons that are embraced in the true answer to the question, “_Why is
+the sea salt?_”
+
+
+HOW TO ASCERTAIN THE SALTNESS OF THE SEA.
+
+Dry a towel in the sun, weigh it carefully, and note its weight. Then
+dip it into sea-water, wring it sufficiently to prevent its dripping,
+and weigh it again; the increase of the weight being that of the water
+imbibed by the cloth. It should then be thoroughly dried, and once more
+weighed; and the excess of this weight above the original weight of the
+cloth shows the quantity of the salt retained by it; then, by comparing
+the weight of this salt with that of the sea-water imbibed by the
+cloth, we shall find what proportion of salt was contained in the water.
+
+
+ALL THE SALT IN THE SEA.
+
+The amount of common Salt in all the oceans is estimated by Schafhäutl
+at 3,051,342 cubic geographical miles. This would be about five times
+more than the mass of the Alps, and only one-third less than that of
+the Himalaya. The sulphate of soda equals 633,644·36 cubic miles, or is
+equal to the mass of the Alps; the chloride of magnesium, 441,811·80
+cubic miles; the lime salts, 109,339·44 cubic miles. The above supposes
+the mean depth to be but 300 metres, as estimated by Humboldt.
+Admitting, with Laplace, that the mean depth is 1000 metres, which is
+more probable, the mass of marine salt will be more than double the
+mass of the Himalaya.--_Silliman’s Journal_, No. 16.
+
+Taking the average depth of the ocean at two miles, and its average
+saltness at 3½ per cent, it appears that there is salt enough in the
+sea to cover to the thickness of one mile an area of 7,000,000 of
+square miles. Admit a transfer of such a quantity of matter from an
+average of half a mile above to one mile below the sea-level, and
+astronomers will show by calculation that it would alter the length of
+the day.
+
+These 7,000,000 of cubic miles of crystal salt have not made the sea
+any fuller.
+
+
+PROPERTIES OF SEA-WATER.
+
+The solid constituents of sea-water amount to about 3½ per cent of
+its weight, or nearly half an ounce to the pound. Its saltness is
+caused as follows: Rivers which are constantly flowing into the
+ocean contain salts varying from 10 to 50, and even 100, grains per
+gallon. They are chiefly common salt, sulphate and carbonate of lime,
+magnesia,[41] soda, potash, and iron; and these are found to constitute
+the distinguishing characteristics of sea-water. The water which
+evaporates from the sea is nearly pure, containing but very minute
+traces of salts. Falling as rain upon the land, it washes the soil,
+percolates through the rocky layers, and becomes charged with saline
+substances, which are borne seaward by the returning currents. The
+ocean, therefore, is the great depository of every thing that water
+can dissolve and carry down from the surface of the continents; and
+as there is no channel for their escape, they consequently accumulate
+(_Youmans’ Chemistry_). They would constantly accumulate, as this very
+shrewd author remarks, were it not for the shells and insects of the
+sea and other agents.
+
+
+SCENERY AND LIFE OF THE ARCTIC REGIONS.
+
+The late Dr. Scoresby, from personal observations made in the course of
+twenty-one voyages to the Arctic Regions, thus describes these striking
+characteristics:
+
+  The coast scenes of Greenland are generally of an abrupt character,
+  the mountains frequently rising in triangular profile; so much
+  so, that it is sometimes not possible to effect their ascent. One
+  of the most notable characteristics of the Arctic lands is the
+  deception to which travellers are liable in regard to distances.
+  The occasion of this is the quantity of light reflected from
+  the snow, contrasted with the dark colour of the rocks. Several
+  persons of considerable experience have been deceived in this way,
+  imagining, for example, that they were close to the shore when in
+  fact they were more than twenty miles off. The trees of these lands
+  are not more than three inches above ground.
+
+  Many of the icebergs are five miles in extent, and some are to be
+  seen running along the shore measuring as much as thirteen miles.
+  Dr. Scoresby has seen a cliff of ice supported on those floating
+  masses 402 feet in height. There is no place in the world where
+  animal life is to be found in greater profusion than in Greenland,
+  Spitzbergen, Baffin’s Bay, and other portions of the Arctic
+  regions. This is to be accounted for by the abundance and richness
+  of the food supplied by the sea. The number of birds is especially
+  remarkable. On one occasion, no less than a million of little hawks
+  came in sight of Dr. Scoresby’s ship within a single hour.
+
+  The various phenomena of the Greenland sea are very interesting.
+  The different colours of the sea-water--olive or bottle-green,
+  reddish-brown, and mustard--have, by the aid of the microscope,
+  been found to be owing to animalculæ of these various colours:
+  in a single drop of mustard-coloured water have been counted
+  26,450 animals. Another remarkable characteristic of the Greenland
+  sea-water is its warm temperature--one, two, and three degrees
+  above the freezing-point even in the cold season. This Dr.
+  Scoresby accounts for by supposing the flow in that direction of
+  warm currents from the south. The polar fields of ice are to be
+  found from eight or nine to thirty or forty feet in thickness. By
+  fastening a hook twelve or twenty inches in these masses of ice, a
+  ship could ride out in safety the heaviest gales.
+
+
+ICEBERG OF THE POLAR SEAS.
+
+The ice of this berg, although opaque and vascular, is true glacier
+ice, having the fracture, lustre, and other external characters of
+a nearly homogeneous growth. The iceberg is true ice, and is always
+dreaded by ships. Indeed, though modified by climate, and especially by
+the alternation of day and night, the polar glacier must be regarded as
+strictly atmospheric in its increments, and not essentially differing
+from the glacier of the Alps. The general appearance of a berg may be
+compared to frosted silver; but when its fractures are very extensive,
+the exposed faces have a very brilliant lustre. Nothing can be more
+exquisite than a fresh, cleanly fractured berg surface: it reminds one
+of the recent cleavage of sulphate of strontian--a resemblance more
+striking from the slightly lazulitic tinge of each.--_U. S. Grinnel
+Expedition in Search of Sir J. Franklin._
+
+
+IMMENSITY OF POLAR ICE.
+
+The quantity of solid matter that is drifted out of the Polar Seas
+through one opening--Davis’s Straits--alone, and during a part of the
+year only, covers to the depth of seven feet an area of 300,000 square
+miles, and weighs not less than 18,000,000,000 tons. The quantity of
+water required to float and drive out this solid matter is probably
+many times greater than this. A quantity of water equal in weight to
+these two masses has to go in. The basin to receive these inflowing
+waters, _i. e._ the unexplored basin about the North Pole, includes an
+area of 1,500,000 square miles; and as the outflowing ice and water are
+at the surface, the return current must be submarine.
+
+These two currents, therefore, it may be perceived, keep in motion
+between the temperate and polar regions of the earth a volume of water,
+in comparison with which the mighty Mississippi in its greatest floods
+sinks down to a mere rill.--_Maury._
+
+
+OPEN SEA AT THE POLE.
+
+The following fact is striking: In 1662-3, Mr. Oldenburg, Secretary to
+the Royal Society, was ordered to register a paper entitled “Several
+Inquiries concerning Greenland, answered by Mr. Gray, who had visited
+those parts.” The nineteenth query was, “How near any one hath been
+known to approach the Pole. _Answer._ I once met upon the coast of
+Greenland a Hollander, that swore he had been but half a degree from
+the Pole, showing me his journal, which was also attested by his mate;
+where _they had seen no ice or land, but all water_.” Boyle mentions
+a similar account, which he received from an old Greenland master, on
+April 5, 1765.
+
+
+RIVER-WATER ON THE OCEAN.
+
+Captain Sabine found discoloured water, supposed to be that of the
+Amazon, 300 miles distant in the ocean from the embouchure of that
+river. It was about 126 feet deep. Its specific gravity was = 1·0204,
+and the specific gravity of the sea-water = 1·0262. This appears to
+be the greatest distance from land at which river-water has been
+detected on the surface of the ocean. It was estimated to be moving
+at the rate of three miles an hour, and had been turned aside by an
+ocean-current. “It is not a little curious to reflect,” says Sir Henry
+de la Beche, “that the agitation and resistance of its particles should
+be sufficient to keep finely comminuted solid matter mechanically
+suspended, so that it would not be disposed freely to part with it
+except at its junction with the sea-water over which it flows, and
+where, from friction, it is sufficiently retarded.”
+
+
+THE THAMES AND ITS SALT-WATER BED.
+
+The Thames below Woolwich, in place of flowing upon a solid bottom,
+really flows upon the liquid bottom formed by the water of the sea.
+At the flow of the tide, the fresh water is raised, as it were, in a
+single mass by the salt water which flows in, and which ascends the
+bed of the river, while the fresh water continues to flow towards the
+sea.--_Mr. Stevenson, in Jameson’s Journal._
+
+
+FRESH SPRINGS IN THE MIDDLE OF THE OCEAN.
+
+On the southern coast of the island of Cuba, at a few miles from land,
+Springs of Fresh Water gush from the bed of the Ocean, probably under
+the influence of hydrostatic pressure, and rise through the midst
+of the salt water. They issue forth with such force that boats are
+cautious in approaching this locality, which has an ill repute on
+account of the high cross sea thus caused. Trading vessels sometimes
+visit these springs to take in a supply of fresh water, which is thus
+obtained in the open sea. The greater the depth from which the water is
+taken, the fresher it is found to be.
+
+
+“THE BLACK WATERS.”
+
+In the upper portion of the basin of the Orinoco and its tributaries,
+Nature has several times repeated the enigmatical phenomenon of the
+so-called “Black Waters.” The Atabapo, whose banks are adorned with
+Carolinias and arborescent Melastomas, is a river of a coffee-brown
+colour. In the shade of the palm-groves this colour seems about to
+pass into ink-black. When placed in transparent vessels, the water
+appears of a golden yellow. The image of the Southern Constellation
+is reflected with wonderful clearness in these black streams. When
+their waters flow gently, they afford to the observer, when taking
+astronomical observations with reflecting instruments, a most excellent
+artificial horizon. These waters probably owe their peculiar colour to
+a solution of carburetted hydrogen, to the luxuriance of the tropical
+vegetation, and to the quantity of plants and herbs on the ground over
+which they flow.--_Humboldt’s Aspects of Nature_, vol. i.
+
+
+GREAT CATARACT IN INDIA.
+
+Where the river Shirhawti, between Bombay and Cape Comorin, falls into
+the Gulf of Arabia, it is about one-fourth of a mile in width, and in
+the rainy season some thirty feet in depth. This immense body of water
+rushes down a rocky slope 300 feet, at an angle of 45°, at the bottom
+of which it makes a perpendicular plunge of 850 feet into a black and
+dismal abyss, with a noise like the loudest thunder. The whole descent
+is therefore 1150 feet, or several times that of Niagara; but the
+volume of water in the latter is somewhat larger than in the former.
+
+
+CAUSE OF WAVES.
+
+The friction of the wind combines with the tide in agitating the
+surface of the ocean, and, according to the theory of undulations,
+each produces its effect independently of the other. Wind, however,
+not only raises waves, but causes a transfer of superficial water
+also. Attraction between the particles of air and water, as well
+as the pressure of the atmosphere, brings its lower stratum into
+adhesive contact with the surface of the sea. If the motion of the
+wind be parallel to the surface, there will still be friction, but the
+water will be smooth as a mirror; but if it be inclined, in however
+small a degree, a ripple will appear. The friction raises a minute
+wave, whose elevation protects the water beyond it from the wind,
+which consequently impinges on the surface at a small angle: thus
+each impulse, combining with the other, produces an undulation which
+continually advances.--_Mrs. Somerville’s Physical Geography._
+
+
+RATE AT WHICH WAVES TRAVEL.
+
+Professor Bache states, as one of the effects of an earthquake at
+Simoda, on the island of Niphon, in Japan, that the harbour was first
+emptied of water, and then came in an enormous wave, which again
+receded and left the harbour dry. This occurred several times. The
+United-States self-acting tide-gauge at San Francisco, which records
+the rise of the tide upon cylinders turned by clocks, showed that at
+San Francisco, 4800 miles from the scene of the earthquake, the first
+wave arrived twelve hours and sixteen minutes after it had receded from
+the harbour of Simoda. It had travelled across the broad bosom of the
+Pacific Ocean at the rate of six miles and a half a minute, and arrived
+on the shores of California: the first wave being seven-tenths of a
+foot in height, and lasting for about half an hour, followed by seven
+lesser waves, at intervals of half an hour each.
+
+The velocity with which a wave travels depends on the depth of the
+ocean. The latest calculations for the Pacific Ocean give a depth of
+from 14,000 to 18,000 fathoms. It is remarkable how the estimates of
+the ocean’s depth have grown less. Laplace assumed it at ten miles,
+Whewell at 3·5, while the above estimate brings it down to two miles.
+
+Mr. Findlay states, that the dynamic force exerted by Sea-Waves is
+greatest at the crest of the wave before it breaks; and its power in
+raising itself is measured by various facts. At Wasburg, in Norway,
+in 1820, it rose 400 feet; and on the coast of Cornwall, in 1843,
+300 feet. The author shows that waves have sometimes raised a column
+of water equivalent to a pressure of from three to five tons the
+square foot. He also proves that the velocity of the waves depends
+on their length, and that waves of from 300 to 400 feet in length
+from crest to crest travel from twenty to twenty-seven and a half
+miles an hour. Waves travel great distances, and are often raised by
+distant hurricanes, having been felt simultaneously at St. Helena
+and Ascension, though 600 miles apart; and it is probable that
+ground-swells often originate at the Cape of Good Hope, 3000 miles
+distant. Dr. Scoresby found the travelling rate of the Atlantic waves
+to be 32·67 English statute miles per hour.
+
+In the winter of 1856, a heavy ground-swell, brought on by five hours’
+gale, scoured away in fourteen hours 3,900,000 tons of pebbles from
+the coast near Dover; but in three days, without any shift of wind,
+upwards of 3,000,000 tons were thrown back again. These figures are to
+a certain extent conjectural; but the quantities have been derived from
+careful measurement of the profile of the beach.
+
+
+OCEAN-HIGHWAYS: HOW SEA-ROUTES HAVE BEEN SHORTENED.
+
+When one looks seaward from the shore, and sees a ship disappear
+in the horizon as she gains an offing on a voyage to India, or the
+Antipodes perhaps, the common idea is that she is bound over a
+trackless waste; and the chances of another ship sailing with the same
+destination the next day, or the next week, coming up and speaking
+with her on the “pathless ocean,” would to most minds seem slender
+indeed. Yet the truth is, the winds and the currents are now becoming
+so well understood, that the navigator, like the backwoodsman in the
+wilderness, is enabled literally to “blaze his way” across the ocean;
+not, indeed, upon trees, as in the wilderness, but upon the wings of
+the wind. The results of scientific inquiry have so taught him how to
+use these invisible couriers, that they, with the calm belts of the
+air, serve as sign-boards to indicate to him the turnings and forks and
+crossings by the way.
+
+  Let a ship sail from New York to California, and the next week let
+  a faster one follow; they will cross each other’s path many times,
+  and are almost sure to see each other by the way, as in the voyage
+  of two fine clipper-ships from New York to California. On the ninth
+  day after the _Archer_ had sailed, the _Flying Cloud_ put to sea.
+  Both ships were running against time, but without reference to
+  each other. The _Archer_, with wind and current charts in hand,
+  went blazing her way across the calms of Cancer, and along the
+  new route down through the north-east trades to the equator; the
+  _Cloud_ followed, crossing the equator upon the trail of Thomas of
+  the _Archer_. Off Cape Horn she came up with him, spoke him, and
+  handed him the latest New York dates. The _Flying Cloud_ finally
+  ranged ahead, made her adieus, and disappeared among the clouds
+  that lowered upon the western horizon, being destined to reach her
+  port a week or more in advance of her Cape Horn consort. Though
+  sighting no land from the time of their separation until they
+  gained the offing of San Francisco,--some six or eight thousand
+  miles off,--the tracks of the two vessels were so nearly the same,
+  that being projected upon the chart, they appear almost as one.
+
+  This is the great course of the ocean: it is 15,000 miles in
+  length. Some of the most glorious trials of speed and of prowess
+  that the world ever witnessed among ships that “walk the waters”
+  have taken place over it. Here the modern clipper-ship--the noblest
+  work that has ever come from the hands of man--has been sent,
+  guided by the lights of science, to contend with the elements, to
+  outstrip steam, and astonish the world.--_Maury._
+
+
+ERROR UPON ERROR.
+
+The great inducement to Mr. Babbage, some years since, to attempt
+the construction of a machine by which astronomical tables could be
+calculated and even printed by mechanical means, and with entire
+accuracy, was the errors in the requisite tables. Nineteen such
+errors, in point of fact, were discovered in an edition of Taylor’s
+_Logarithms_ printed in 1796; some of which might have led to the
+most dangerous results in calculating a ship’s place. These nineteen
+errors (of which one only was an error of the press) were pointed out
+in the _Nautical Almanac_ for 1832. In one of these _errata_, the seat
+of the error was stated to be in cosine of 14° 18′ 3″. Subsequent
+examination showed that there was an error of one second in this
+correction, and accordingly, in the _Nautical Almanac_ of the next
+year a new correction was necessary. But in making the new correction
+of one second, a new error was committed of ten degrees, making it
+still necessary, in some future edition of the _Nautical Almanac_,
+to insert an _erratum_ in an _erratum_ of the _errata_ in Taylor’s
+_Logarithms_.--_Edinburgh Review_, vol. 59.
+
+
+
+
+Phenomena of Heat.
+
+
+THE LENGTH OF THE DAY AND THE HEAT OF THE EARTH.
+
+As we may judge of the uniformity of temperature from the unaltered
+time of vibration of a pendulum, so we may also learn from the
+unaltered rotatory velocity of the earth the amount of stability in the
+mean temperature of our globe. This is the result of one of the most
+brilliant applications of the knowledge we had long possessed of the
+movement of the heavens to the thermic condition of our planet. The
+rotatory velocity of the earth depends on its volume; and since, by the
+gradual cooling of the mass by radiation, the axis of rotation would
+become shorter, the rotatory velocity would necessarily increase, and
+the length of the day diminish with a decrease of the temperature. From
+the comparison of the secular inequalities in the motions of the moon
+with the eclipses observed in former ages, it follows that, since the
+time of Hipparchus,--that is, for full 2000 years,--the length of the
+day has certainly not diminished by the hundredth part of a second. The
+decrease of the mean heat of the globe during a period of 2000 years
+has not therefore, taking the extremest limits, diminished as much as
+1/306th of a degree of Fahrenheit.[42]--_Humboldt’s Cosmos_, vol. i.
+
+
+NICE MEASUREMENT OF HEAT.
+
+A delicate thermometer, placed on the ground, will be affected by the
+passage of a single cloud across a clear sky; and if a succession of
+clouds pass over, with intervals of clear sky between them, such an
+instrument has been observed to fluctuate accordingly, rising with each
+passing mass of vapour, and falling again when the radiation becomes
+unrestrained.
+
+
+EXPENDITURE OF HEAT BY THE SUN.
+
+Sir John Herschel estimates the total Expenditure of Heat by the Sun in
+a given time, by supposing a cylinder of ice 45 miles in diameter to be
+continually darted into the sun _with the velocity of light_, and that
+the water produced by its fusion were continually carried off: the heat
+now given off constantly by radiation would then be wholly expended in
+its liquefaction, on the one hand, so as to leave no radiant surplus;
+while, on the other, the actual temperature at its surface would
+undergo no diminution.
+
+The great mystery, however, is to conceive how so enormous a
+conflagration (if such it be) can be kept up. Every discovery in
+chemical science here leaves us completely at a loss, or rather
+seems to remove further the prospect of probable explanation. If
+conjecture might be hazarded, we should look rather to the known
+possibility of an indefinite generation of heat by friction, or to
+its excitement by the electric discharge, than to any combustion of
+ponderable fuel, whether solid or gaseous, for the origin of the solar
+radiation.--_Outlines._[43]
+
+
+DISTINCTIONS OF HEAT.
+
+Among the curious laws of modern science are those which regulate the
+transmission of radiant heat through transparent bodies. The heat of
+our fires is intercepted and detained by screens of glass, and, being
+so detained, warms them; while solar heat passes freely through and
+produces no such effect. “The more recent researches of Delaroche,”
+says Sir John Herschel, “however, have shown that this detention is
+complete only when the temperature of the source of heat is low; but
+that as the temperature gets higher a portion of the heat radiated
+acquires a power of penetrating glass, and that the quantity which does
+so bears continually a larger and larger proportion to the whole, as
+the heat of the radiant body is more intense. This discovery is very
+important, as it establishes a community of nature between solar and
+terrestrial heat; while at the same time it leads us to regard the
+actual temperature of the sun as far exceeding that of any earthly
+flame.”
+
+
+LATENT HEAT.
+
+This extraordinary principle exists in all bodies, and may be pressed
+out of them. The blacksmith hammers a nail until it becomes red hot,
+and from it he lights the match with which he kindles the fire of his
+forge. The iron has by this process become more dense, and percussion
+will not again produce incandescence until the bar has been exposed in
+fire to a red heat, when it absorbs heat, the particles are restored to
+their former state, and we can again by hammering develop both heat and
+light.--_R. Hunt, F.R.S._
+
+
+HEAT AND EVAPORATION.
+
+In a communication made to the French Academy, M. Daubrée calculates
+that the Evaporation of the Water on the surface of the globe employs a
+quantity of heat about equal to one-third of what is received from the
+sun; or, in other words, equal to the melting of a bed of ice nearly
+thirty-five feet in thickness if spread over the globe.
+
+
+HEAT AND MECHANICAL POWER.
+
+It has been found that Heat and Mechanical Power are mutually
+convertible; and that the relation between them is definite, 772
+foot-pounds of motive power being equivalent to a unit of heat, that
+is, to the amount of heat requisite to raise a pound of water through
+one degree of Fahrenheit.
+
+
+HEAT OF MINES.
+
+One cause of the great Heat of many of our deep Mines, which appears to
+have been entirely lost sight of, is the chemical action going on upon
+large masses of pyritic matter in their vicinity. The heat, which is so
+oppressive in the United Mines in Cornwall that the miners work nearly
+naked, and bathe in water at 80° to cool themselves, is without doubt
+due to the decomposition of immense quantities of the sulphurets of
+iron and copper known to be in this condition at a short distance from
+these mineral works.--_R. Hunt, F.R.S._
+
+
+VIBRATION OF HEATED METALS.
+
+Mr. Arthur Trevelyan discovered accidentally that a bar of iron, when
+heated and placed with one end on a solid block of lead, in cooling
+vibrates considerably, and produces sounds similar to those of an
+Æolian harp. The same effect is produced by bars of copper, zinc,
+brass, and bell-metal, when heated and placed on blocks of lead, tin,
+or pewter. The bars were four inches long, one inch and a half wide,
+and three-eighths of an inch thick.
+
+The conditions essential to these experiments are, That two different
+metals must be employed--the one soft and possessed of moderate
+conducting powers, viz. lead or tin, the other hard; and it matters not
+whether soft metal be employed for the bar or block, provided the soft
+metal be cold and the hard metal heated.
+
+That the surface of the block shall be uneven, for when rendered quite
+smooth the vibration does not take place; but the bar cannot be too
+smooth.
+
+That no matter be interposed, else it will prevent vibration, with
+the exception of a burnish of gold leaf, the thickness of which cannot
+amount to the two-hundred-thousandth part of an inch.--_Transactions of
+the Royal Society of Edinburgh._
+
+
+EXPANSION OF SPIRITS.
+
+Spirits expand and become lighter by means of heat in a greater
+proportion than water, wherefore they are heaviest in winter. A cubic
+inch of brandy has been found by many experiments to weigh ten grains
+more in winter than in summer, the difference being between four drams
+thirty-two grains and four drams forty-two grains. Liquor-merchants
+take advantage of this circumstance, and make their purchases in winter
+rather than in summer, because they get in reality rather a larger
+quantity in the same bulk, buying by measure.--_Notes in Various
+Sciences._
+
+
+HEAT PASSING THROUGH GLASS.
+
+The following experiment is by Mr. Fox Talbot: Heat a poker bright-red
+hot, and having opened a window, apply the poker quickly very near
+to the outside of a pane, and the hand to the inside; a strong heat
+will be felt at the instant, which will cease as soon as the poker
+is withdrawn, and may be again renewed and made to cease as quickly
+as before. Now it is well known, that if a piece of glass is so much
+warmed as to convey the impression of heat to the hand, it will retain
+some part of that heat for a minute or more; but in this experiment the
+heat will vanish in a moment: it will not, therefore, be the heated
+pane of glass that we shall feel, but heat which has come through the
+glass in a free or radiant state.
+
+
+HEAT FROM GAS-LIGHTING.
+
+In the winter of 1835, Mr. W. H. White ascertained the temperature in
+the City to be 3° higher than three miles south of London Bridge; and
+_after the gas had been lighted in the City_ four or five hours the
+temperature increased full 3°, thus making 6° difference in the three
+miles.
+
+
+HEAT BY FRICTION.
+
+Friction as a source of Heat is well known: we rub our hands to
+warm them, and we grease the axles of carriage-wheels to prevent
+their setting fire to the wood. Count Rumford has established the
+extraordinary fact, that an unlimited supply of heat may be derived
+from friction by the same materials: he made great quantities of water
+boil by causing a blunt borer to rub against a mass of metal immersed
+in the water. Savages light their fires by rubbing two pieces of wood:
+the _modus operandi_, as practised by the Kaffirs of South Africa, is
+thus described by Captain Drayton:
+
+  Two dry sticks, one being of hard and the other of soft wood, were
+  the materials used. The soft stick was laid on the ground, and
+  held firmly down by one Kaffir, whilst another employed himself
+  in scooping out a little hole in the centre of it with the point
+  of his assagy: into this little hollow the end of the hard wood
+  was placed, and held vertically. These two men sat face to face,
+  one taking the vertical stick between the palms of his hands, and
+  making it twist about very quickly, while the other Kaffir held the
+  lower stick firmly in its place; the friction caused by the end of
+  one piece of wood revolving upon the other soon made the two pieces
+  smoke. When the Kaffir who twisted became tired, the respective
+  duties were exchanged. These operations having continued about a
+  couple of minutes, sparks began to appear, and when they became
+  numerous, were gathered into some dry grass, which was then swung
+  round at arm’s length until a blaze was established; and a roaring
+  fire was gladdening the hearts of the Kaffirs with the anticipation
+  of a glorious feast in about ten minutes from the time that the
+  operation was first commenced.
+
+
+HEAT BY FRICTION FROM ICE.
+
+When Sir Humphry Davy was studying medicine at Penzance, one of his
+constant associates was Mr. Tom Harvey, a druggist in the above town.
+They constantly experimented together; and one severe winter’s day,
+after a discussion on the nature of heat, the young philosophers were
+induced to go to Larigan river, where Davy succeeded in developing heat
+by _rubbing two pieces of ice together_ so as to melt each other;[44]
+an experiment which he repeated with much _éclat_ many years after,
+in the zenith of his celebrity, at the Royal Institution. The pieces
+of ice for this experiment are fastened to the ends of two sticks,
+and rubbed together in air below the temperature of 32°: this Davy
+readily accomplished on the day of severe cold at the Larigan river;
+but when the experiment was repeated at the Royal Institution, it was
+in the vacuum of an air-pump, when the temperature of the apparatus and
+of the surrounding air was below 32°. It was remarked, that when the
+surface of the rubbing pieces was rough, only half as much heat was
+evolved as when it was smooth. When the pressure of the rubbing piece
+was increased four times, the proportion of heat evolved was increased
+sevenfold.
+
+
+WARMING WITH ICE.
+
+In common language, any thing is understood to be cooled or warmed when
+the temperature thereof is made higher or lower, whatever may have been
+the temperature when the change was commenced. Thus it is said that
+melted iron is _cooled_ down to a sub-red heat, or mercury is cooled
+from the freezing point to zero, or far below. By the same rule, solid
+mercury, say 50° below zero, may, in any climate or temperature of the
+atmosphere, be immediately warmed and melted by being imbedded in a
+cake of ice.--_Scientific American._
+
+
+REPULSION BY HEAT.
+
+If water is poured upon an iron sieve, the wires of which are made
+red-hot, it will not run through; but on cooling, it will pass through
+rapidly. M. Boutigny, pursuing this curious inquiry, has proved
+that the moisture upon the skin is sufficient to protect it from
+disorganisation if the arm is plunged into baths of melted metal.
+The resistance of the surfaces is so great that little elevation of
+temperature is experienced. Professor Plücker has stated, that by
+washing the arm with ether previously to plunging it into melted metal,
+the sensation produced while in the molten mass is that of freezing
+coldness.--_R. Hunt, F.R.S._
+
+
+PROTECTION FROM INTENSE HEAT.
+
+The singular power which the body possesses of resisting great heats,
+and of breathing air of high temperatures, has at various times excited
+popular wonder. In the last century some curious experiments were
+made on this subject. Sir Joseph Banks, Dr. Solander, and Sir Charles
+Blagden, entered a room in which the air had a temperature of 198°
+Fahr., and remained ten minutes. Subsequently they entered the room
+separately, when Dr. Solander found the heat 210°, and Sir Joseph
+211°, whilst their bodies preserved their natural degree of heat.
+Whenever they breathed upon a thermometer, it sank several degrees;
+every inspiration gave coolness to their nostrils, and their breath
+cooled their fingers when it reached them. Sir Charles Blagden entered
+an apartment when the heat was 1° or 2° above 260°, and remained eight
+minutes, mostly on the coolest spot, where the heat was above 240°.
+Though very hot, Sir Charles felt no pain: during seven minutes his
+breathing was good; but he then felt an oppression in his lungs, and
+his pulse was 144, double its ordinary quickness. To prove the heat of
+the room, eggs and a beefsteak were placed upon a tin frame near the
+thermometer, when in twenty minutes the eggs were roasted hard, and in
+forty-seven minutes the steak was dressed dry; and when the air was put
+in motion by a pair of bellows upon another steak, part of it was well
+done in thirteen minutes. It is remarkable, that in these experiments
+the same person who experienced no inconvenience from air heated to
+211°, could just bear rectified spirits of wine at 130°, cooling oil at
+129°, cooling water at 123°, and cooling quicksilver at 117°.
+
+Sir Francis Chantrey, the sculptor, however, exposed himself to a
+temperature still higher than any yet mentioned, as described by Sir
+David Brewster:
+
+  The furnace which he employs for drying his moulds is about
+  fourteen feet long, twelve feet high, and twelve feet broad. When
+  it is raised to its highest temperature, with the doors closed,
+  the thermometer stands at 350°, and the iron floor is red-hot. The
+  workmen often enter it at a temperature of 340°, walking over the
+  iron floor with wooden clogs, which are of course charred on the
+  surface. On one occasion, Mr. Chantrey, accompanied by five or
+  six of his friends, entered the furnace; and after remaining two
+  minutes they brought out a thermometer which stood at 320°. Some
+  of the party experienced sharp pains in the tips of their ears
+  and in the septum of the nose, while others felt a pain in their
+  eyes.--_Natural Magic_, 1833.
+
+In some cases the clothing worn by the experimenters conducts away
+the heat. Thus, in 1828, a Spaniard entered a heated oven, at the New
+Tivoli, near Paris; he sang a song while a fowl was roasted by his
+side, he then ate the fowl and drank a bottle of wine, and on coming
+out his pulse beat 176°, and the thermometer was at 110° Reaumur. He
+then stretched himself upon a plank in the oven surrounded by lighted
+candles, when the mouth of the oven was closed; he remained there five
+minutes, and on being taken out, all the candles were extinguished and
+melted, and the Spaniard’s pulse beat 200°. Now much of the surprise
+ceases when it is added that he wore wide woollen pantaloons, a loose
+mantle of wool, and a great quilted cap; the several materials of this
+clothing being bad conductors of heat.
+
+In 1829 M. Chabert, the “Fire-King,” exhibited similar feats at the
+Argyll Rooms in Regent Street. He first swallowed forty grains of
+phosphorus, then two spoonfuls of oil at 330°, and next held his head
+over the fumes of sulphuric acid. He had previously provided himself
+with an antidote for the poison of the phosphorus. Dressed in a loose
+woollen coat, he then entered a heated oven, and in five minutes cooked
+two steaks; he then came out of the oven, when the thermometer stood at
+380°. Upon another occasion, at White Conduit House, some of his feats
+were detected.
+
+The scientific secret is as follows: Muscular tissue is an extremely
+bad conductor; and to this in a great measure the constancy of the
+temperature of the human body in various zones is to be attributed. To
+this fact also Sir Charles Blagden and Chantrey owed their safety in
+exposing their bodies to a high temperature; from the almost impervious
+character of the tissues of the body, the irritation produced was
+confined to the surface.
+
+
+
+
+Magnetism and Electricity.
+
+
+MAGNETIC HYPOTHESES.
+
+As an instance of the obstacles which erroneous hypotheses throw
+in the way of scientific discovery, Professor Faraday adduces the
+unsuccessful attempts that had been made in England to educe Magnetism
+from Electricity until Oersted showed the simple way. Faraday relates,
+that when he came to the Royal Institution as an assistant in the
+laboratory, he saw Davy, Wollaston, and Young trying, by every way that
+suggested itself to them, to produce magnetic effects from an electric
+current; but having their minds diverted from the true course by their
+existing hypotheses, it did not occur to them to try the effect of
+holding a wire through which an electric current was passing over a
+suspended magnetic needle. Had they done so, as Oersted afterwards did,
+the immediate deflection of the needle would have proved the magnetic
+property of an electric current. Faraday has shown that the magnetism
+of a steel bar is caused by the accumulated action of all the particles
+of which it is composed: this he proves by first magnetising a small
+steel bar, and then breaking it successively into smaller and smaller
+pieces, each one of which possesses a separate pole; and the same
+operation may be continued until the particles become so small as not
+to be distinguishable without a microscope.
+
+We quote the above from a late Number of the _Philosophical Magazine_,
+wherein also we find the following noble tribute to the genius and
+public and private worth of Faraday:
+
+  The public never can know and appreciate the national value of such
+  a man as Faraday. He does not work to please the public, nor to win
+  its guineas; and the said public, if asked its opinion as to the
+  practical value of his researches, can see no possible practical
+  issue there. The public does not know that we need prophets
+  more than mechanics in science,--inspired men, who, by patient
+  self-denial and the exercise of the high intellectual gifts of the
+  Creator, bring us intelligence of His doings in Nature. To them
+  their pursuits are good in themselves. Their chief reward is the
+  delight of being admitted into communion with Nature, the pleasure
+  of tracing out and proclaiming her laws, wholly forgetful whether
+  those laws will ever augment our banker’s account or improve our
+  knowledge of cookery. _Such men, though not honoured by the title
+  of “practical,” are they which make practical men possible._
+  They bring us the tamed forces of Nature, and leave it to others
+  to contrive the machinery to which they may be yoked. If we are
+  rightly informed, it was Faradaic electricity which shot the glad
+  tidings of the fall of Sebastopol from Balaklava to Varna. Had
+  this man converted his talent to commercial purposes, as so many
+  do, we should not like to set a limit to his professional income.
+  The quality of his services cannot be expressed by pounds; but
+  that brave body, which for forty years has been the instrument
+  of that great soul, is a fit object for a nation’s care, as the
+  achievements of the man are, or will one day be, the object of a
+  nation’s pride and gratitude.
+
+
+THE CHINESE AND THE MAGNETIC NEEDLE.
+
+More than a thousand years before our era, a people living in the
+extremest eastern portions of Asia had magnetic carriages, on which the
+movable arm of the figure of a man continually pointed to the south,
+as a guide by which to find the way across the boundless grass-plains
+of Tartary; nay, even in the third century of our era, therefore at
+least 700 years before the use of the mariner’s compass in European
+seas, Chinese vessels navigated the Indian Ocean under the direction of
+Magnetic Needles pointing to the south.
+
+  Now the Western nations, the Greeks and the Romans, knew that
+  magnetism could be communicated to iron, and _that that metal_
+  would retain it for a length of time. The great discovery of
+  the terrestrial directive force depended, therefore, alone
+  on this--that no one in the West had happened to observe an
+  elongated fragment of magnetic iron-stone, or a magnetic iron rod,
+  floating by the aid of a piece of wood in water, or suspended
+  in the air by a thread, in such a position as to admit of free
+  motion.--_Humboldt’s Cosmos_, vol. i.
+
+
+KIRCHER’S “MAGNETISM.”
+
+More than two centuries since, Athanasius Kircher published his strange
+book on Magnetism, in which he anticipated the supposed virtue of
+magnetic traction in the curative art, and advocated the magnetism
+of the sun and moon, of the divining-rod, and showed his firm belief
+in animal magnetism. “In speaking of the vegetable world,” says Mr.
+Hunt, “and the remarkable processes by which the leaf, the flower,
+and the fruit are produced, this sage brings forward the fact of the
+diamagnetic (repelled by the magnet) character of the plant which was
+in 1852 rediscovered; and he refers the motions of the sunflower, the
+closing of the convolvulus, and the directions of the spiral formed
+by the twining plants, to this particular influence.”[45] Nor were
+Kircher’s anticipations random guesses, but the result of deductions
+from experiment and observation; and the universality of magnetism is
+now almost recognised by philosophers.
+
+
+MINUTE MEASUREMENT OF TIME.
+
+By observing the magnet in the highly-convenient and delicate manner
+introduced by Gauss and Weber, which consists in attaching a mirror
+to the magnet and determining the constant factor necessary to convert
+the differences of oscillation into differences of time, Professor
+Helmholtz has been able, with comparatively simple apparatus, to make
+accurate determinations up to the 1/10000th part of a second.
+
+
+POWER OF A MAGNET.
+
+The Power of a Magnet is estimated by the weight its poles are able
+to carry. Each pole singly is able to support a smaller weight than
+when they both act together by means of a keeper, for which reason
+horse-shoe magnets are superior to bar magnets of similar dimensions
+and character. It has further been ascertained that small magnets have
+a much greater relative force than large ones.
+
+When magnetism is excited in a piece of steel in the ordinary mode, by
+friction with a magnet, it would seem that its inductive power is able
+to overcome the coercive power of the steel only to a certain depth
+below the surface; hence we see why small pieces of steel, especially
+if not very hard, are able to carry greater relative weights than large
+magnets. Sir Isaac Newton wore in a ring a magnet weighing only 3
+grains, which would lift 760 grains, _i. e._ 250 times its own weight.
+
+Bar-magnets are seldom found capable of carrying more than their own
+weight; but horse-shoe magnets of similar steel will bear considerably
+more. Small ones of from half an ounce to 1 ounce in weight will carry
+from 30 to 40 times their own weight; while such as weigh from 1 to 2
+lbs. will rarely carry more than from 10 to 15 times their weight. The
+writer found a 1 lb. horse-shoe magnet that he impregnated by means of
+the feeder able to bear 26½ times its own weight; and Fischer, having
+adopted the like mode of magnetising the steel, which he also carefully
+heated, has made magnets of from 1 to 3 lbs. weight that would carry 30
+times, and others of from 4 to 6 lbs. weight that would carry 20 times,
+their own weight.--_Professor Peschel._
+
+
+HOW ARTIFICIAL MAGNETS ARE MADE.
+
+In 1750, Mr. Canton, F.R.S., “one of the most successful experimenters
+in the golden age of electricity,”[46] communicated to the Royal
+Society his “Method of making Artificial Magnets without the use
+of natural ones.” This he effected by using a poker and tongs to
+communicate magnetism to steel bars. He derived his first hint from
+observing them one evening, as he was sitting by the fire, to be nearly
+in the same direction with the earth as the dipping needle. He thence
+concluded that they must, from their position and the frequent blows
+they receive, have acquired some magnetic virtue, which on trial he
+found to be the case; and therefore he employed them to impregnate his
+bars, instead of having recourse to the natural loadstone. Upon the
+reading of the above paper, Canton exhibited to the Royal Society his
+experiments, for which the Copley Medal was awarded to him in 1751.
+
+Canton had, as early as 1747, turned his attention, with complete
+success, to the production of powerful artificial magnets, principally
+in consequence of the expense of procuring those made by Dr. Gowan
+Knight, who kept his process secret. Canton for several years abstained
+from communicating his method even to his most intimate friends,
+lest it might be injurious to Dr. Knight, who procured considerable
+pecuniary advantages by touching needles for the mariner’s compass.
+
+At length Dr. Knight’s method of making artificial magnets was
+communicated to the world by Mr. Wilson, in a paper published in the
+69th volume of the _Philosophical Transactions_. He provided himself
+with a large quantity of clean iron-filings, which he put into a
+capacious tub about half full of clear water; he then agitated the
+tub to and fro for several hours, until the filings were reduced by
+attrition to an almost impalpable powder. This powder was then dried,
+and formed into paste by admixture with linseed-oil. The paste was then
+moulded into convenient shapes, which were exposed to a moderate heat
+until they had attained a sufficient degree of hardness.
+
+  After allowing them to remain for some time in this state, Dr.
+  Knight gave them their magnetic virtue in any direction he pleased,
+  by placing them between the extreme ends of his large magazine of
+  artificial magnets for a second or more, as he saw occasion. By
+  this method the virtue they acquired was such, that when any one of
+  these pieces was held between two of his best ten-guinea bars, with
+  its poles purposely inverted, it immediately of itself turned about
+  to recover its natural direction, which the force of those very
+  powerful bars was not sufficient to counteract.
+
+Dr. Knight’s powerful battery of magnets above mentioned is in the
+possession of the Royal Society, having been presented by Dr. John
+Fothergill in 1776.
+
+
+POWER OF THE SUN’S RAYS IN INCREASING THE STRENGTH OF MAGNETS.
+
+Professor Barlocci found that an armed natural loadstone, which would
+carry 1½ Roman pounds, had its power nearly _doubled_ by twenty-four
+hours’ exposure to the strong light of the sun. M. Zantedeschi found
+that an artificial horse-shoe loadstone, which carried 13½ oz., carried
+3½ more by three days’ exposure, and at last arrived to 31 oz. by
+continuing it in the sun’s light. He found that while the strength
+increased in oxidated magnets, it diminished in those which were not
+oxidated, the diminution becoming insensible when the loadstone was
+highly polished. He now concentrated the solar rays upon the loadstone
+by means of a lens; and he found that, both in oxidated and polished
+magnets, they _acquire_ strength when their _north_ pole is exposed
+to the sun’s rays, and _lose_ strength when the _south_ pole is
+exposed.--_Sir David Brewster._
+
+
+COLOUR OF A BODY AND ITS MAGNETIC PROPERTIES.
+
+Solar rays bleach dead vegetable matter with rapidity, while in living
+parts of plants their action is frequently to strengthen the colour.
+Their power is perhaps best seen on the sides of peaches, apples, &c.,
+which, exposed to a midsummer’s sun, become highly coloured. In the
+open winter of 1850, Mr. Adie, of Liverpool, found in a wallflower
+plant proof of a like effect: in the dark months there was a slow
+succession of one or two flowers, of uniform pale yellow hue; in March
+streaks of a darker colour appeared on the flowers, and continued to
+slowly increase till in April they were variegated brown and yellow,
+of rich strong colours. On the supposition that these changes are
+referable to magnetic properties, may hereafter be explained Mrs.
+Somerville’s experiments on steel needles exposed to the sun’s rays
+under envelopes of silk of various colours; the magnetisation of steel
+needles has failed in the coloured rays of the spectrum, but Mr. Adie
+considers that under dyed silk the effect will hinge on the chemical
+change wrought in the silk and its dye by the solar rays.
+
+
+THE ONION AND MAGNETISM.
+
+A popular notion has long been current, more especially on the shores
+of the Mediterranean, that if a magnetic rod be rubbed with an onion,
+or brought in contact with the emanations of the plant, the directive
+force will be diminished, while a compass thus treated will mislead the
+steersman. It is difficult to conceive what could have given rise to so
+singular a popular error.[47]--_Humboldt’s Cosmos_, vol. v.
+
+
+DECLINATION OF THE NEEDLE--THE EARTH A MAGNET.
+
+The Inclination or Dip of the Needle was first recorded by Robert
+Norman, in a scarce book published in 1576 entitled _The New
+Attractive; containing a short Discourse of the Magnet or Loadstone,
+&c._
+
+Columbus has not only the merit of being the first to discover _a
+line without magnetic variation_, but also of having first excited a
+taste for the study of terrestrial magnetism in Europe, by means of
+his observations on the progressive increase of western declination in
+receding from that line.
+
+The first chart showing the variation of the compass,[48] or the
+declination of the needle, based on the idea of employing curves drawn
+through points of equal declination, is due to Halley, who is justly
+entitled the father and founder of terrestrial magnetism. And it is
+curious to find that in No. 195 of the _Philosophical Transactions_,
+in 1683, Halley had previously expressed his belief that he has put it
+past doubt that the globe of the earth is one great magnet, having four
+magnetical poles or points of attraction, near each pole of the equator
+two; and that in those parts of the world which lie near adjacent to
+any one of those magnetical poles, the needle is chiefly governed
+thereby, the nearest pole being always predominant over the more remote.
+
+“To Halley” (says Sir John Herschel) “we owe the first appreciation
+of the real complexity of the subject of magnetism. It is wonderful
+indeed, and a striking proof of the penetration and sagacity of this
+extraordinary man, that with his means of information he should
+have been able to draw such conclusions, and to take so large and
+comprehensive a view of the subject as he appears to have done.”
+
+And, in our time, “the earth is a great magnet,” says Faraday: “its
+power, according to Gauss, being equal to that which would be conferred
+if every cubic yard of it contained six one-pound magnets; the sum of
+the force is therefore equal to 8,464,000,000,000,000,000,000 such
+magnets.”
+
+
+THE AURORA BOREALIS.
+
+Halley, upon his return from his voyage to verify his theory of the
+variation of the compass, in 1700, hazarded the conjecture that the
+Aurora Borealis is a magnetic phenomenon. And Faraday’s brilliant
+discovery of the evolution of light by magnetism has raised Halley’s
+hypothesis, enounced in 1714, to the rank of an experimental certainty.
+
+
+EFFECT OF LIGHT ON THE MAGNET.
+
+In 1854, Sir John Ross stated to the British Association, in proof of
+the effect of every description of light on the magnet, that during
+his last voyage in the _Felix_, when frozen in about one hundred miles
+north of the magnetic pole, he concentrated the rays of the full moon
+on the magnetic needle, when he found it was five degrees attracted by
+it.
+
+
+MAGNETO-ELECTRICITY.
+
+In 1820, the Copley Medal was adjudicated to M. Oersted of Copenhagen,
+“when,” says Dr. Whewell, “the philosopher announced that the
+conducting-wire of a voltaic circuit acts upon a magnetic needle; and
+thus recalled into activity that endeavour to connect magnetism with
+electricity which, though apparently on many accounts so hopeful, had
+hitherto been attended with no success. Oersted found that the needle
+has a tendency to place itself at _right angles_ to the wire; a kind of
+action altogether different from any which had been suspected.”
+
+
+ELECTRO-MAGNETS OF THE HORSE-SHOE FORM
+
+were discovered by Sturgeon in 1825. Of two Magnets made by a process
+devised by M. Elias, and manufactured by M. Logemeur at Haerlem, one,
+a single horse-shoe magnet weighing about 1 lb., lifts 28½ lbs.; the
+other, a triple horse-shoe magnet of about 10 lbs. weight, is capable
+of lifting about 150 lbs. Similar magnets are made by the same person
+capable of supporting 5 cwt. In the process of making them, a helix of
+copper and a galvanic battery are used. The smaller magnet has twice
+the power expressed by Haecker’s formula for the best artificial steel
+magnet.
+
+Subsequently Henry and Ten Eyk, in America, constructed some
+electro-magnets on a large scale. One horse-shoe magnet made by them,
+weighing 60 lbs., would support more than 2000 lbs.
+
+In September 1858, there were constructed for the Atlantic-telegraph
+cable at Valentia two permanent magnets, from which the electric
+induction is obtained: each is composed of 30 horse-shoe magnets, 2½
+feet long and from 4 to 5 inches broad; the induction coils attached to
+these each contain six miles of wire, and a shock from them, if passed
+through the human body, would be sufficient to destroy life.
+
+
+ROTATION-MAGNETISM.
+
+The unexpected discovery of Rotation-Magnetism by Arago, in 1825,
+has shown practically that every kind of matter is susceptible of
+magnetism; and the recent investigations of Faraday on diamagnetic
+substances have, under special conditions of meridian or equatorial
+direction, and of solid, fluid, or gaseous inactive conditions of the
+bodies, confirmed this important result.
+
+
+INFLUENCE OF PENDULUMS ON EACH OTHER.
+
+About a century since it became known, that when two clocks are in
+action upon the same shelf, they will disturb each other: that the
+pendulum of the one will stop that of the other; and that the pendulum
+that was stopped will after a while resume its vibrations, and in its
+turn stop that of the other clock. When two clocks are placed near
+one another in cases very slightly fixed, or when they stand on the
+boards of a floor, they will affect a little each other’s pendulum.
+Mr. Ellicote observed that two clocks resting against the same rail,
+which agreed to a second for several days, varied one minute thirty-six
+seconds in twenty-four hours when separated. The slower, having a
+longer pendulum, set the other in motion in 16-1/3 minutes, and stopped
+itself in 36-2/3 minutes.
+
+
+WEIGHT OF THE EARTH ASCERTAINED BY THE PENDULUM.
+
+By a series of comparisons with Pendulums placed at the surface and
+the interior of the Earth, the Astronomer-Royal has ascertained the
+variation of gravity in descending to the bottom of a deep mine, as
+the Harton coal-pit, near South Shields. By calculations from these
+experiments, he has found the mean density of the earth to be 6·566,
+the specific gravity of water being represented by unity. In other
+words, it has been ascertained by these experiments that if the earth’s
+mass possessed every where its average density, it would weigh, bulk
+for bulk, 6·566 times as much as water. It is curious to note the
+different values of the earth’s mean density which have been obtained
+by different methods. The Schehallien experiment indicated a mean
+density equal to about 4½; the Cavendish apparatus, repeated by Baily
+and Reich, about 5½; and Professor Airy’s pendulum experiment furnishes
+a value amounting to about 6½.
+
+The immediate result of the computations of the Astronomer-Royal is:
+supposing a clock adjusted to go true time at the top of the mine, it
+would gain 2¼ seconds per day at the bottom. Or it may be stated thus:
+that gravity is greater at the bottom of a mine than at the top by
+1/19190th part.--_Letter to James Mather, Esq., South Shields._ See
+also _Professor Airy’s Lecture_, 1854.
+
+
+ORIGIN OF TERRESTRIAL MAGNETISM.
+
+The earliest view of Terrestrial Magnetism supposed the existence
+of a magnet at the earth’s centre. As this does not accord with the
+observations on declination, inclination, and intensity, Tobias
+Meyer gave this fictitious magnet an eccentric position, placing it
+one-seventh part of the earth’s radius from the centre. Hansteen
+imagined that there were two such magnets, different in position
+and intensity. Ampère set aside these unsatisfactory hypotheses by
+the view, derived from his discovery, that the earth itself is an
+electro-magnet, magnetised by an electric current circulating about
+it from east to west perpendicularly to the plane of the magnetic
+meridian, to which the same currents give direction as well as
+magnetise the ores of iron: the currents being thermo-electric
+currents, excited by the action of the sun’s heat successively on the
+different parts of the earth’s surface as it revolves towards the east.
+
+William Gilbert,[49] who wrote an able work on magnetic and electric
+forces in the year 1600, regarded terrestrial magnetism and electricity
+as two emanations of a single fundamental source pervading all matter,
+and he therefore treated of both at once. According to Gilbert’s idea,
+the earth itself is a magnet; whilst he considered that the inflections
+of the lines of equal declination and inclination depend upon the
+distribution of mass, the configuration of continents, or the form and
+extent of the deep intervening oceanic basins.
+
+Till within the last eighty years, it appears to have been the received
+opinion that the intensity of terrestrial magnetism was the same at
+all parts of the earth’s surface. In the instructions drawn up by
+the French Academy for the expedition under La Pérouse, the first
+intimation is given of a contrary opinion. It is recommended that the
+time of vibration of a dipping-needle should be observed at stations
+widely remote, as a test of the equality or difference of the magnetic
+intensity; suggesting also that such observations should particularly
+be made at those parts of the earth where the dip was greatest and
+where it was least. The experiments, whatever their results may have
+been, which, in compliance with this recommendation, were made in the
+expedition of La Pérouse, perished in its general catastrophe; but the
+instructions survived.
+
+In 1811, Hansteen took up the subject, and in 1819 published his
+celebrated work, clearly demonstrating the fluctuations which this
+element has undergone during the last two centuries; confirming in
+great detail the position of Halley, that “the whole magnetic system is
+in motion, that the moving force is very great as extending its effects
+from pole to pole, and that its motion is not _per saltum_, but a
+gradual and regular motion.”
+
+
+THE NORTH AND SOUTH MAGNETIC POLES.
+
+The knowledge of the geographical position of both Magnetic Poles is
+due to the scientific energy of the same navigator, Sir James Ross.
+His observations of the Northern Magnetic Pole were made during the
+second expedition of his uncle, Sir John Ross (1829-1833); and of
+the Southern during the Antarctic expedition under his own command
+(1839-1843). The Northern Magnetic Pole, in 70° 5′ lat., 96° 43′ W.
+long., is 5° of latitude farther from the ordinary pole of the earth
+than the Southern Magnetic Pole, 75° 35′ lat., 154° 10′ E. long.;
+whilst it is also situated farther west from Greenwich than the
+Northern Magnetic Pole. The latter belongs to the great island of
+Boothia Felix, which is situated very near the American continent,
+and is a portion of the district which Captain Parry had previously
+named North Somerset. It is not far distant from the western coast of
+Boothia Felix, near the promontory of Adelaide, which extends into King
+William’s Sound and Victoria Strait.
+
+The Southern Magnetic Pole has been directly reached in the same manner
+as the Northern Pole. On 17th February 1841, the _Erebus_ penetrated
+as far as 76° 12′ S. lat., and 164° E. long. As the inclination was
+here only 88° 40′, it was assumed that the Southern Magnetic Pole
+was about 160 nautical miles distant. Many accurate observations of
+declination, determining the intersection of the magnetic meridian,
+render it very probable that the South Magnetic Pole is situated in the
+interior of the great Antarctic region of South Victoria Land, west
+of the Prince Albert mountains, which approach the South Pole and are
+connected with the active volcano of Erebus, which is 12,400 feet in
+height.--_Humboldt’s Cosmos_, vol. v.
+
+
+MAGNETIC STORMS.
+
+The mysterious course of the magnetic needle is equally affected by
+time and space, by the sun’s course, and by changes of place on the
+earth’s surface. Between the tropics the hour of the day may be known
+by the direction of the needle as well as by the oscillations of the
+barometer. It is affected instantly, but transiently, by the northern
+light.
+
+When the uniform horary motion of the needle is disturbed by a magnetic
+storm, the perturbation manifests itself _simultaneously_, in the
+strictest sense of the word, over hundreds and thousands of miles of
+sea and land, or propagates itself by degrees in short intervals every
+where over the earth’s surface.
+
+Among numerous examples of perturbations occurring simultaneously and
+extending over wide portions of the earth’s surface, one of the most
+remarkable is that of September 25th, 1841, which was observed at
+Toronto in Canada, at the Cape of Good Hope, at Prague, and partially
+in Van Diemen’s Land. Sabine adds, “The English Sunday, on which it is
+deemed sinful, after midnight on Saturday, to register an observation,
+and to follow out the great phenomena of creation in their perfect
+development, interrupted the observation in Van Diemen’s Land, where,
+in consequence of the difference of the longitude, the magnetic storm
+fell on Sunday.”
+
+  It is but justice to add, that to the direct instrumentality of the
+  British Association we are indebted for this system of observation,
+  which would not have been possible without some such machinery
+  for concerted action. It being known that the magnetic needle is
+  subject to oscillations, the nature, the periods, and the laws
+  of which were unascertained, under the direction of a committee
+  of the Association _magnetic observatories_ were established in
+  various places for investigating these strange disturbances. As
+  might have been anticipated, regularly recurring perturbations were
+  noted, depending on the hour of the day and the season of the year.
+  Magnetic storms were observed to sweep simultaneously over the
+  whole face of the earth, and these too have now been ascertained to
+  follow certain periodic laws.
+
+  But the most startling result of the combined magnetic observations
+  is the discovery of marked perturbations recurring at intervals of
+  ten years; a period which seemed to have no analogy to any thing
+  in the universe, but which M. Schwabe has found to correspond
+  with the variation of the spots on the sun, both attaining their
+  maximum and minimum developments at the same time. Here, for the
+  present, the discovery stops; but that which is now an unexplained
+  coincidence may hereafter supply the key to the nature and source
+  of Terrestrial Magnetism: or, as Dr. Lloyd observes, this system of
+  magnetic observation has gone beyond our globe, and opened a new
+  range for inquiry, by showing us that this wondrous agent has power
+  in other parts of the solar system.
+
+
+FAMILIAR GALVANIC EFFECTS.
+
+By means of the galvanic agency a variety of surprising effects have
+been produced. Gunpowder, cotton, and other inflammable substances have
+been set on fire; charcoal has been made to burn with a brilliant white
+flame; water has been decomposed into its elementary parts; metals
+have been melted and set on fire; fragments of diamond, charcoal, and
+plumbago have been dispersed as if evaporated; platina, the hardest
+and the heaviest of the metals, has been melted as readily as wax in
+the flame of a candle; the sapphire, quartz, magnesia, lime, and the
+firmest compounds in nature, have been fused. Its effects on the animal
+system are no less surprising.
+
+The agency of galvanism explains why porter has a different and more
+pleasant taste when drunk out of a pewter-pot than out of glass or
+earthenware; why works of metal which are soldered together soon
+tarnish in the place where the metals are joined; and why the copper
+sheathing of ships, when fastened with iron nails, is soon corroded
+about the place of contact. In all these cases a galvanic circle is
+formed which produces the effects.
+
+
+THE SIAMESE TWINS GALVANISED.
+
+It will be recollected that the Siamese twins, brought to England in
+the year 1829, were united by a jointed cartilaginous band. A silver
+tea spoon being placed on the tongue of one of the twins and a disc of
+zinc on the tongue of the other, the moment the two metals were brought
+into contact both the boys exclaimed, “Sour, sour;” thus proving that
+the galvanic influence passed from the one to the other through the
+connecting band.
+
+
+MINUTE AND VAST BATTERIES.
+
+Dr. Wollaston made a simple apparatus out of a silver thimble, with its
+top cut off. It was then partially flattened, and a small plate of zinc
+being introduced into it, the apparatus was immersed in a weak solution
+of sulphuric acid. With this minute battery, Dr. Wollaston was able to
+fuse a wire of platinum 1/3000th of an inch in diameter--a degree of
+tenuity to which no one had ever succeeded in drawing it.
+
+Upon the same principle (that of introducing a plate of zinc between
+two plates of other metals) Mr. Children constructed his immense
+battery, the zinc plates of which measured six feet by two feet eight
+inches; each plate of zinc being placed between two of copper, and each
+triad of plates being enclosed in a separate cell. With this powerful
+apparatus a wire of platinum, 1/10th of an inch in diameter and upwards
+of five feet long, was raised to a red heat, visible even in the broad
+glare of daylight.
+
+The great battery at the Royal Institution, with which Sir Humphry Davy
+discovered the composition of the fixed alkalies, was of immense power.
+It consisted of 200 separate parts, each composed of ten double plates,
+and each plate containing thirty-two square inches; the number of
+double plates being 2000, and the whole surface 128,000 square inches.
+
+Mr. Highton, C.E., has made a battery which exposes a surface of only
+1/100th part of an inch: it consists of but one cell; it is less than
+1/10000th part of a cubic inch, and yet it produces electricity more
+than enough to overcome all the resistance in the inventor’s brother’s
+patent Gold-leaf Telegraph, and works the same powerfully. It is, in
+short, a battery which, although _it will go through the eye of a
+needle_, will yet work a telegraph well. Mr. Highton had previously
+constructed a battery in size less than 1/40th of a cubic inch: this
+battery, he found, would for a month together ring a telegraph-bell ten
+miles off.
+
+
+ELECTRIC INCANDESCENCE OF CHARCOAL POINTS.
+
+The most splendid phenomenon of this kind is the combustion of charcoal
+points. Pointed pieces of the residuum obtained from gas retorts will
+answer best, or Bunsen’s composition may be used for this purpose. Put
+two such charcoal points in immediate contact with the wires of your
+battery; bring the points together, and they will begin to burn with
+a dazzling white light. The charcoal points of the large apparatus
+belonging to the Royal Institution became incandescent at a distance of
+1/30th of an inch; when the distance was gradually increased till they
+were four inches asunder, they continued to burn with great intensity,
+and a permanent stream of light played between them. Professor Bunsen
+obtained a similar flame from a battery of four pairs of plates,
+its carbon surface containing 29 feet. The heat of this flame is so
+intense, that stout platinum wire, sapphire, quartz, talc, and lime
+are reduced by it to the liquid form. It is worthy of remark, that no
+combustion, properly so called, takes place in the charcoal itself,
+which sustains only an extremely minute loss in its weight and becomes
+rather denser at the points. The phenomenon is attended with a still
+more vivid brightness if the charcoal points are placed in a vacuum,
+or in any of those gases which are not supporters of combustion.
+Instead of two charcoal points, one only need be used if the following
+arrangement is adopted: lay the piece of charcoal on some quicksilver
+that is connected with one pole of the battery, and complete the
+circuit from the other pole by means of a strip of platinum. When
+Professor Peschel used a piece of well-burnt coke in the manner just
+described, he obtained a light which was almost intolerable to the eyes.
+
+
+VOLTAIC ELECTRICITY.
+
+On January 31, 1793, Volta announced to the Royal Society his discovery
+of the development of electricity in metallic bodies. Galvani had given
+the name of Animal Electricity to the power which caused spontaneous
+convulsions in the limbs of frogs when the divided nerves were
+connected by a metallic wire. Volta, however, saw the true cause of the
+phenomena described by Galvani. Observing that the effects were far
+greater when the connecting medium consisted of two different kinds
+of metal, he inferred that the principle of excitation existed in the
+metals, and not in the nerves of the animal; and he assumed that the
+exciting fluid was ordinary electricity, produced by the contact of the
+two metals; the convulsions of the frog consequently arose from the
+electricity thus developed passing along its nerves and muscles.
+
+In 1800 Volta invented what is now called the Voltaic Pile, or compound
+Galvanic circle.
+
+  The term Animal Electricity (says Dr. Whewell) has been superseded
+  by others, of which _Galvanism_ is the most familiar; but I think
+  that Volta’s office in this discovery is of a much higher and more
+  philosophical kind than that of Galvani; and it would on this
+  account be more fitting to employ the term _Voltaic Electricity_,
+  which, indeed, is very commonly used, especially by our most
+  recent and comprehensive writers. The _Voltaic pile_ was a more
+  important step in the history of electricity than the Leyden jar
+  had been--_Hist. Ind. Sciences_, vol. iii.
+
+  No one who wishes to judge impartially of the scientific history
+  of these times and of its leaders, will consider Galvani and
+  Volta as equals, or deny the vast superiority of the latter over
+  all his opponents or fellow-workers, more especially over those
+  of the Bologna school. We shall scarcely again find in one man
+  gifts so rich and so calculated for research as were combined
+  in Volta. He possessed that “incomprehensible talent,” as Dove
+  has called it, for separating the essential from the immaterial
+  in complicated phenomena; that boldness of invention which must
+  precede experiment, controlled by the most strict and cautious
+  mode of manipulation; that unremitting attention which allows no
+  circumstance to pass unnoticed; lastly, with so much acuteness,
+  so much simplicity, so much grandeur of conception, combined with
+  such depth of thought, he had a hand which was the hand of a
+  workman.--_Jameson’s Journal_, No. 106.
+
+
+THE VOLTAIC BATTERY AND THE GYMNOTUS.
+
+“We boast of our Voltaic Batteries,” says Mr. Smee. “I should hardly
+be believed if I were to say that I did not feel pride in having
+constructed my own, especially when I consider the extensive operations
+which it has conducted. But when I compare my battery with the battery
+which nature has given to the electrical eel and the torpedo, how
+insignificant are human operations compared with those of the Architect
+of living beings! The stupendous electric eel in the Polytechnic
+Institution, when he seeks to kill his prey, encloses him in a circle;
+then, by volition, causes the voltaic force to be produced, and the
+hapless creature is instantly killed. It would probably require ten
+thousand of my artificial batteries to effect the same object, as
+the creature is killed _instanter_ on receiving the shock. As much,
+however, as my battery is inferior to that of the electric fish, so
+is man superior to the same animal. Man is endowed with a power of
+mind competent to appreciate the force of matter, and is thus enabled
+to make the battery. The eel can but use the specific apparatus which
+nature has bestowed upon it.”
+
+Some observations upon the electric current around the gymnotus, and
+notes of experiments with this and other electric fish, will be found
+in _Things not generally Known_, p. 199.
+
+
+VOLTAIC CURRENTS IN MINES.
+
+Many years ago, Mr. R. W. Fox, from theory entertaining a belief
+that a connection existed between voltaic action in the interior of
+the earth and the arrangement of metalliferous veins, and also the
+progressive increase of temperature in the strata as we descend from
+the surface, endeavoured to verify the same from experiment in the mine
+of Huel Jewel, in Cornwall. His apparatus consisted of small plates
+of sheet-copper, which were fixed in contact with a plate in the veins
+with copper nails, or else wedged closely against them with wooden
+props stretched across the galleries. Between two of these plates,
+at different stations, a communication was made by means of a copper
+wire 1/20th of an inch in diameter, which included a galvanometer
+in its circuit. In some instances 300 fathoms of copper wire were
+employed. It was then found that the intensity of the voltaic current
+was generally greater in proportion to the greater abundance of copper
+ore in the veins, and in some degree to the depth of the stations.
+Hence Mr. Fox’s discovery promised to be of practical utility to the
+miner in discovering the relative quantity of ore in the veins, and the
+directions in which it most abounds.
+
+The result of extended experiments, mostly made by Mr. Robert Hunt,
+has not, however, confirmed Mr. Fox’s views. It has been found that
+the voltaic currents detected in the lodes are due to the chemical
+decomposition going on there; and the more completely this process
+of decomposition is established, the more powerful are the voltaic
+currents. Meanwhile these have nothing whatever to do with the increase
+of temperature with depth. Recent observations, made in the deep mines
+of Cornwall under the direction of Mr. Fox, do not appear consistent
+with the law of thermic increase as formerly established, the shallow
+mines giving a higher ratio of increase than the deeper ones.
+
+
+GERMS OF ELECTRIC KNOWLEDGE.
+
+Two centuries and a half ago, Gilbert recognised that the property of
+attracting light substances when rubbed, be their nature what it may,
+is not peculiar to amber, which is a condensed earthy juice cast up by
+the waves of the sea, and in which flying insects, ants, and worms lie
+entombed as in eternal sepulchres. The force of attraction (Gilbert
+continues) belongs to a whole class of very different substances, as
+glass, sulphur, sealing-wax, and all resinous substances--rock crystal
+and all precious stones, alum and rock-salt. Gilbert measured the
+strength of the excited electricity by means of a small needle--not
+made of iron--which moved freely on a pivot, and perfectly similar to
+the apparatus used by Haüy and Brewster in testing the electricity
+excited in minerals by heat and friction. “Friction,” says Gilbert
+further, “is productive of a stronger effect in dry than in humid air;
+and rubbing with silk cloths is most advantageous.”
+
+Otto von Guerike, the inventor of the air-pump, was the first who
+observed any thing more than mere phenomena of attraction. In his
+experiments with a rubbed piece of sulphur he recognised the
+phenomena of repulsion, which subsequently led to the establishment
+of the laws of the sphere of action and of the distribution of
+electricity. _He heard the first sound, and saw the first light, in
+artificially-produced electricity._ In an experiment instituted by
+Newton in 1675, the first traces of an electric charge in a rubbed
+plate of glass were seen.
+
+
+TEMPERATURE AND ELECTRICITY.
+
+Professor Tyndall has shown that all variations of temperature, in
+metals at least, excite electricity. When the wires of a galvanometer
+are brought in contact with the two ends of a heated poker, the prompt
+deflection of the galvanometer-needle indicates that a current of
+electricity has been sent through the instrument. Even the two ends of
+a spoon, one of which has been dipped in hot water, serve to develop an
+electric current; and in cutting a hot beefsteak with a steel knife and
+a silver fork there is an excitement of electricity. The mere heat of
+the finger is sufficient to cause the deflection of the galvanometer;
+and when ice is applied to the part that has been previously warmed,
+the galvanometer-needle is deflected in the contrary direction. A small
+instrument invented by Melloni is so extremely sensitive of the action
+of heat, that electricity is excited when the hand is held six inches
+from it.
+
+
+VAST ARRANGEMENT OF ELECTRICITY.
+
+Professor Faraday has shown that the Electricity which decomposes,
+and that which is evolved in the decomposition of, a certain quantity
+of matter, are alike. What an enormous quantity of electricity,
+therefore, is required for the decomposition of a single grain of
+water! It must be in quantity sufficient to sustain a platinum wire
+1/104th of an inch in thickness red-hot in contact with the air
+for three minutes and three-quarters. It would appear that 800,000
+charges of a Leyden battery, charged by thirty turns of a very large
+and powerful plate-machine in full action, are necessary to supply
+electricity sufficient to decompose a single grain of water, or to
+equal the quantity of electricity which is naturally associated with
+the elements of that grain of water, endowing them with their mutual
+chemical affinity. Now the above quantity of electricity, if passed at
+once through the head of a rat or a cat, would kill it as by a flash of
+lightning. The quantity is, indeed, equal to that which is developed
+from a charged thunder-cloud.
+
+
+DECOMPOSITION OF WATER BY ELECTRICITY.
+
+Professor Andrews, by an ingenious arrangement, is enabled to show that
+water is decomposed by the common machine; and by using an electrical
+kite, he was able, in fine weather, to produce decomposition, although
+so slowly that only 1/700000th of a grain of water was decomposed per
+hour. Faraday has proved that the decomposition of one single grain of
+water produces more electricity than is contained in the most powerful
+flash of lightning.
+
+
+ELECTRICITY IN BREWING.
+
+Mr. Black, a practical writer upon Brewing, has found that by the
+practice of imbedding the fermentation-vats in the earth, and
+connecting them by means of metallic pipes, an electrical current
+passes through the beer and causes it to turn sour. As a preventive,
+he proposed to place the vats upon wooden blocks, or on any other
+non-conductors, so that they may be insulated. It has likewise been
+ascertained that several brewers who had brewed excellent ale on the
+south side of the street, on removing to the north have failed to
+produce good ale.
+
+
+ELECTRIC PAPER.
+
+Professor Schonbein has prepared paper, as transparent as glass and
+impermeable to water, which develops a very energetic electric force.
+By placing some sheets on each other, and simply rubbing them once or
+twice with the hand, it becomes difficult to separate them. If this
+experiment is performed in the dark, a great number of distinct flashes
+may be perceived between the separated surfaces. The disc of the
+electrophorus, placed on a sheet that has been rubbed, produces sparks
+of some inches in length. A thin and very dry sheet of paper, placed
+against the wall, will adhere strongly to it for several hours if the
+hand be passed only once over it. If the same sheet be passed between
+the thumb and fore-finger in the dark, a luminous band will be visible.
+Hence with this paper may be made powerful and cheap electrical
+machines.
+
+
+DURATION OF THE ELECTRIC SPARK.
+
+By means of Professor Wheatstone’s apparatus, the Duration
+of the Electric Spark has been ascertained not to exceed the
+twenty-five-thousandth part of a second. A cannon-ball, if illumined
+in its flight by a flash of lightning, would, in consequence of the
+momentary duration of the light, appear to be stationary, and even the
+wings of an insect, that move ten thousand times in a second, would
+seem at rest.
+
+
+VELOCITY OF ELECTRIC LIGHT.
+
+On comparing the velocities of solar, stellar, and terrestrial light,
+which are all equally refracted in the prism, with the velocity of the
+light of frictional electricity, we are disposed, in accordance with
+Wheatstone’s ingeniously-conducted experiments, to regard the lowest
+ratio in which the latter excels the former as 3:2. According to the
+lowest results of Wheatstone’s apparatus, electric light traverses
+288,000 miles in a second. If we reckon 189,938 miles for stellar
+light, according to Struve, we obtain the difference of 95,776 miles as
+the greater velocity of electricity in one second.
+
+From the experiment described in Wheatstone’s paper (_Philosophical
+Transactions_ for 1834), it would appear that the human eye is capable
+of perceiving phenomena of light whose duration is limited to the
+millionth part of a second.
+
+In Professor Airy’s experiments with the electric telegraph to
+determine the difference of longitude between Greenwich and Brussels,
+the time spent by the electric current in passing from one observatory
+to the other (270 miles) was found to be 0·109″ or rather more than
+_the ninth part of a second_; and this determination rests on 2616
+observations: a speed which would “girdle the globe” in ten seconds.
+
+
+IDENTITY OF ELECTRIC AND MAGNETIC ATTRACTION.
+
+This vague presentiment of the ancients has been verified in our own
+times. “When electrum (amber),” says Pliny, “is animated by friction
+and heat, it will attract bark and dry leaves precisely as the
+loadstone attracts iron.” The same words may be found in the literature
+of an Asiatic nation, and occur in a eulogium on the loadstone by the
+Chinese physicist Knopho, in the fourth century: “The magnet attracts
+iron as amber does the smallest grain of mustard-seed. It is like
+a breath of wind, which mysteriously penetrates through both, and
+communicates itself with the rapidity of an arrow.”
+
+  Humboldt observed with astonishment on the woody banks of the
+  Orinoco, in the sports of the natives, that the excitement of
+  electricity by friction was known to these savage races. Children
+  may be seen to rub the dry, flat, and shining seeds or husks of a
+  trailing plant until they are able to attract threads of cotton
+  and pieces of bamboo-cane. What a chasm divides the electric
+  pastime of these naked copper-coloured Indians from the discovery
+  of a metallic conductor discharging its electric shocks, or a
+  pile formed of many chemically-decomposing substances, or a
+  light-engendering magnetic apparatus! In such a chasm lie buried
+  thousands of years, that compose the history of the intellectual
+  development of mankind.--_Humboldt’s Cosmos_, vol. i.
+
+
+THEORY OF THE ELECTRO-MAGNETIC ENGINE.
+
+Several years ago a speculative American set the industrial world of
+Europe in excitement by this proposition. The Magneto-Electric Machines
+often made use of in the case of rheumatic disorders are well known. By
+imparting a swift rotation to the magnet of such a machine, we obtain
+powerful currents of electricity. If these be conducted through water,
+the latter will be reduced to its two components, oxygen and hydrogen.
+By the combustion of hydrogen water is again generated. If this
+combustion takes place, not in atmospheric air, in which oxygen only
+constitutes a fifth part, but in pure oxygen, and if a bit of chalk be
+placed in the flame, the chalk will be raised to a white heat, and give
+us the sun-like Drummond light: at the same time the flame develops a
+considerable quantity of heat. Now the American inventor proposed to
+utilise in this way the gases obtained from electrolytic decomposition;
+and asserted that by the combustion a sufficient amount of heat was
+generated to keep a small steam-engine in action, which again drove his
+magneto-electric machine, decomposed the water, and thus continually
+prepared its own fuel. This would certainly have been the most splendid
+of all discoveries,--a perpetual motion which, besides the force that
+kept it going, generated light like the sun, and warmed all around it.
+The affair, however, failed, as was predicted by those acquainted with
+the physical investigations which bear upon the subject.--_Professor
+Helmholtz._
+
+
+MAGNETIC CLOCK AND WATCH.
+
+In the Museum of the Royal Society are two curiosities of the
+seventeenth century which are objects of much interest in association
+with the electric discoveries of our day. These are a Clock, described
+by the Count Malagatti (who accompanied Cosmo III., Grand Duke of
+Tuscany, to inspect the Museum in 1669) as more worthy of observation
+than all the other objects in the cabinet. Its “movements are derived
+from the vicinity of a loadstone, and it is so adjusted as to discover
+the distance of countries at sea by the longitude.” The analogy
+between this clock and the electric clock of the present day is very
+remarkable. Of kindred interest is “Hook’s Magnetic Watch,” often
+alluded to in the Royal Society’s Journal-book of 1669 as “going slower
+or faster according to the greater or less distance of the loadstone,
+and so moving regularly in any posture.”
+
+
+WHEATSTONE’S ELECTRO-MAGNETIC CLOCK.
+
+In this ingenious invention, the object of Professor Wheatstone was
+to enable a simple clock to indicate exactly the same time in as many
+different places, distant from each other, as may be required. A
+standard clock in an observatory, for example, would thus keep in order
+another clock in each apartment, and that too with such accuracy, that
+_all of them, however numerous, will beat dead seconds audibly with as
+great precision as the standard astronomical time-piece with which
+they are connected_. But, besides this, the subordinate time-pieces
+thus regulated require none of the mechanism for maintaining or
+regulating the power. They consist simply of a face, with its second,
+minute, and hour hands, and a train of wheels which communicate motion
+from the action of the second-hand to that of the hour-hand, in the
+same manner as an ordinary clock-train. Nor is this invention confined
+to observatories and large establishments. The great horologe of St.
+Paul’s might, by a suitable network of wires, or even by the existing
+metallic pipes of the metropolis, be made to command and regulate all
+the other steeple-clocks in the city, and even every clock within the
+precincts of its metallic bounds. As railways and telegraphs extend
+from London nearly to the remotest cities and villages, the sensation
+of time may be transmitted along with the elements of language; and
+the great cerebellum of the metropolis may thus constrain by its
+sympathies, and regulate by its power, the whole nervous system of the
+empire.
+
+
+HOW TO MAKE A COMMON CLOCK ELECTRIC.
+
+M. Kammerer of Belgium effects this by an addition to any clock
+whereby it is brought into contact with the two poles of a galvanic
+battery, the wires from which communicate with a drum moved by the
+clockwork; and every fifteen seconds the current is changed, the
+positive and the negative being transmitted alternately. A wire
+is continued from the drum to the electric clock, the movement of
+which, through the plate-glass dial, is seen to be two pairs of small
+straight electro-magnets, each pair having their ends opposite to the
+other pair, with about half an inch space between. Within this space
+there hangs a vertical steel bar, suspended from a spindle at the
+top. The rod has two slight projections on each side parallel to the
+ends of the wire-coiled magnets. When the electric current comes on
+the wire from the positive end of the battery (through the drum of
+the regulator-clock) the positive magnets attract the bar to it, the
+distance being perhaps the sixteenth of an inch. When, at the end of
+fifteen seconds, the negative pole operates, repulsion takes effect,
+and the bar moves to the opposite side. This oscillating bar gives
+motion to a wheel which turns the minute and hour hands.
+
+M. Kammerer states, that if the galvanic battery be attached to any
+particular standard clock, any number of clocks, wherever placed, in a
+city or kingdom, and communicating with this by a wire, will indicate
+precisely the same time. Such is the precision, that the sounds
+of three clocks thus beating simultaneously have been mistaken as
+proceeding from one clock.
+
+
+DR. FRANKLIN’S ELECTRICAL KITE.
+
+Several philosophers had observed that lightning and electricity
+possessed many common properties; and the light which accompanied
+the explosion, the crackling noise made by the flame, and other
+phenomena, made them suspect that lightning might be electricity in
+a highly powerful state. But this connection was merely the subject
+of conjecture until, in the year 1750, Dr. Franklin suggested an
+experiment to determine the question. While he was waiting for the
+building of a spire at Philadelphia, to which he intended to attach
+his wire, the experiment was successfully made at Marly-la-Ville, in
+France, in the year 1752; when lightning was actually drawn from the
+clouds by means of a pointed wire, and it was proved to be really the
+electric fluid.
+
+  Almost every early electrical discovery of importance was made by
+  Fellows of the Royal Society, and is to be found recorded in the
+  _Philosophical Transactions_. In the forty-fifth volume occurs the
+  first mention of Dr. Franklin’s name, and his theory of positive
+  and negative electricity. In 1756 he was elected into the Society,
+  “without any fee or other payment.” His previous communications
+  to the _Transactions_, particularly the account of his electrical
+  kite, had excited great interest. (_Weld’s History of the
+  Royal Society._) It is thus described by him in a letter dated
+  Philadelphia, October 1, 1752:
+
+  “As frequent mention is made in the public papers from Europe
+  of the success of the Marly-la-Ville experiment for drawing the
+  electric fire from clouds by means of pointed rods of iron erected
+  on high buildings, &c., it may be agreeable to the curious to be
+  informed that the same experiment has succeeded in Philadelphia,
+  though made in a different and more easy manner, which any one may
+  try, as follows:
+
+  Make a small cross of two light strips of cedar, the arms so
+  long as to reach to the four corners of a large thin silk
+  handkerchief when extended. Tie the comers of the handkerchief
+  to the extremities of the cross; so you have the body of a kite,
+  which, being properly accommodated with a tail, loop, and string,
+  will rise in the air like a kite made of paper; but this, being of
+  silk, is fitter to bear the wet and wind of a thunder-gust without
+  tearing. To the top of the upright stick of the cross is to be
+  fixed a very sharp-pointed wire, rising a foot or more above the
+  wood. To the end of the twine, next the band, is to be tied a silk
+  ribbon; and where the twine and silk join a key may be fastened.
+
+  The kite is to be raised when a thunder-gust appears to be coming
+  on, and the person who holds the string must stand within a door
+  or window, or under some cover, so that the silk ribbon may not be
+  wet; and care must be taken that the twine does not touch the frame
+  of the door or window. As soon as any of the thunder-clouds come
+  over the kite, the pointed wire will draw the electric fire from
+  them; and the kite, with all the twine, will be electrified; and
+  the loose filaments of the twine will stand out every way, and be
+  attracted by an approaching finger.
+
+  When the rain has wet the kite and twine, so that it can conduct
+  the electric fire freely, you will find it stream out plentifully
+  from the key on the approach of your knuckle. At this key the phial
+  may be charged; and from electric fire thus obtained spirits may
+  be kindled, and all the other electrical experiments be performed
+  which are usually done by the help of a rubbed-glass globe or tube;
+  and thus the sameness of the electric matter with that of lightning
+  is completely demonstrated.”--_Philosophical Transactions._
+
+Of all this great man’s (Franklin’s) scientific excellencies, the most
+remarkable is the smallness, the simplicity, the apparent inadequacy
+of the means which he employed in his experimental researches. His
+discoveries were all made with hardly any apparatus at all; and if
+at any time he had been led to employ instruments of a somewhat less
+ordinary description, he never rested satisfied until he had, as it
+were, afterwards translated the process by resolving the problem with
+such simple machinery that you might say he had done it wholly unaided
+by apparatus. The experiments by which the identity of lightning and
+electricity was demonstrated were made with a sheet of brown paper, a
+bit of twine or silk thread, and an iron key!--_Lord Brougham._[50]
+
+
+FATAL EXPERIMENT WITH LIGHTNING.
+
+These experiments are not without danger; and a flash of lightning has
+been found to be a very unmanageable instrument. In 1753, M. Richman,
+at St. Petersburg, was making an experiment of this kind by drawing
+lightning into his room, when, incautiously bringing his head too near
+the wire, he was struck dead by the flash, which issued from it like a
+globe of blue fire, accompanied by a dreadful explosion.
+
+
+FARADAY’S ELECTRICAL ILLUSTRATIONS.
+
+The following are selected from the very able series of lectures
+delivered by Professor Faraday at the Royal Institution:
+
+  _The Two Electricities._--After having shown by various experiments
+  the attractions and repulsions of light substances from excited
+  glass and from an excited tube of gutta-percha, Professor Faraday
+  proceeds to point out the difference in the character of the
+  electricity produced by the friction of the two substances. The
+  opposite characters of the electricity evolved by the friction
+  of glass and of that excited by the friction of gutta-percha
+  and shellac are exhibited by several experiments, in which the
+  attraction of the positive and negative electricities to each other
+  and the neutralisation of electrical action on the combination
+  of the two forces are distinctly observable. Though adopting the
+  terms “positive” and “negative” in distinguishing the electricity
+  excited by glass from that excited by gutta-percha and resinous
+  bodies, Professor Faraday is strongly opposed to the Franklinian
+  theory from which these terms are derived. According to Franklin’s
+  view of the nature of electrical excitement, it arises from the
+  disturbance, by friction or other means, of the natural quantity
+  of one electric fluid which is possessed by all bodies; an excited
+  piece of glass having more than its natural share, which has
+  been taken from the rubber, the latter being consequently in a
+  minus or negative state. This theory Professor Faraday considers
+  to be opposed to the distinct characteristic actions of the two
+  forces; and, in his opinion, it is impossible to deprive any body
+  of electricity, and reduce it to the minus state of Franklin’s
+  hypothesis. Taking a Zamboni’s pile, he applies its two ends
+  separately to an electrometer, to show that each end produces
+  opposite kinds of electricity, and that the zero, or absence of
+  electrical excitement, only exists in the centre of the pile. To
+  prove how completely the two electricities neutralise each other,
+  an excited rod of gutta-percha and the piece of flannel with which
+  it has been rubbed are laid on the top of the electrometer without
+  any sign of electricity whilst they are together; but when either
+  is removed, the gold leaves diverge with positive and negative
+  electricity alternately. The Professor dwells strongly on the
+  peculiarity of the dual force of electricity, which, in respect
+  of its duality, is unlike any other force in nature. He then
+  contrasts its phenomena of instantaneous conduction with those of
+  the somewhat analogous force of heat; and he illustrates by several
+  striking experiments the peculiar property which static electricity
+  possesses of being spread only over the surfaces of bodies. A metal
+  ice-pail is placed on an insulated stand and electrified, and a
+  metal ball suspended by a string is introduced, and touches the
+  bottom and sides without having any electricity imparted to it,
+  but on touching the outside it becomes strongly electrical. The
+  experiment is repeated with a wooden tub with the same result;
+  and Professor Faraday mentions the still more remarkable manner
+  in which he has proved the surface distribution of electricity
+  by having a small chamber constructed and covered with tinfoil,
+  which can be insulated; and whilst torrents of electricity are
+  being evolved from the external surface, he enters it with a
+  galvanometer, and cannot perceive the slightest manifestation of
+  electricity within.
+
+  _The Two Threads._--A curious experiment is made with two kinds
+  of thread used as the conducting force. From the electric machine
+  on the table a silk thread is first carried to the indicator a
+  yard or two off, and is shown to be a non-conductor when the glass
+  tube is rubbed and applied to the machine (although the silk, when
+  wetted, conducted); while a metallic thread of the same thickness,
+  when treated in the same way, conducts the force so much as to
+  vehemently agitate the gold leaves within the indicator.
+
+  _Non-conducting Bodies._--The action that occurs in bodies which
+  cannot conduct is the most important part of electrical science.
+  The principle is illustrated by the attraction and repulsion of
+  an electrified ball of gilt paper by a glass tube, between which
+  and the ball a sheet of shellac is suspended. The nearer a ball of
+  another description--an unelectrical insulated body--is brought
+  to the Leyden jar when charged, the greater influence it is seen
+  to possess over the gold leaf within the indicator, by induction,
+  not by conduction. The questions, how electricities attract each
+  other, what kind of electricity is drawn from the machine to the
+  hand, how the hand was electric, are thus illustrated. To show the
+  divers operations of this wonderful force, a tub (a bad conductor)
+  is placed by the electric machine. When the latter is charged, a
+  ball, having been electrified from it, is held in the tub, and
+  rattles against its sides and bottom. On the application of the
+  ball to the indicator, the gold leaf is shown not to move, whereas
+  it is agitated manifestly when the same process is gone through
+  with the exception that the ball is made to touch the outside only
+  of the tub. Similar experiments with a ball in an ice-pail and
+  a vessel of wire-gauze, into the latter of which is introduced a
+  mouse, which is shown to receive no shock, and not to be frightened
+  at all; while from the outside of the vessel electric sparks are
+  rapidly produced. This latter demonstration proves that, as the
+  mouse, so men and women, might be safe inside a building with
+  proper conductors while lightning played about the exterior. The
+  wire-gauze being turned inside out, the principle is shown to be
+  irreversible in spite of the change--what has been the unelectrical
+  inside of the vessel being now, when made the outside portion,
+  capable of receiving and transmitting the power, while the original
+  outside is now unelectrical.
+
+  _Repulsion of Bodies._--A remarkable and playful experiment, by
+  which the repulsion of bodies similarly electrified is illustrated,
+  consists in placing a basket containing a heap of small pieces
+  of paper on an insulated stand, and connecting it with the prime
+  conductor of the electrical machine; when the pieces of paper
+  rise rapidly after each other into the air, and descend on the
+  lecture-table like a fall of snow. The effect is greatly increased
+  when a metal disc is substituted for the basket.
+
+
+ORIGIN OF THE LEYDEN JAR.
+
+Muschenbroek and Linnæus had made various experiments of a strong kind
+with water and wire. The former, as appears from a letter of his to
+Réaumur, filled a small bottle with water, and having corked it up,
+passed a wire through the cork into the bottle. Having rubbed the
+vessel on the outside and suspended it to the electric machine, he was
+surprised to find that on trying to pull the wire out he was subjected
+to an awfully severe shock in his joints and his whole body, such as he
+declared he would not suffer again for any experiment. Hence the Leyden
+jar, which owes its name to the University of Leyden, with which, we
+believe, Muschenbroek was connected.--_Faraday._
+
+
+DANGER TO GUNPOWDER MAGAZINES.
+
+By the illustration of a gas globule, which is ignited from a spark by
+induction, Mr. Faraday has proved in a most interesting manner that the
+corrugated-iron roofs of some gunpowder-magazines,--on the subject of
+which he had often been consulted by the builders, with a view to the
+greater safety of these manufactories,--are absolutely dangerous by the
+laws of induction; as, by the return of induction, while a storm was
+discharging itself a mile or two off, a secondary spark might ignite
+the building.
+
+
+ARTIFICIAL CRYSTALS AND MINERALS.--“THE CROSSE MITE.”
+
+Among the experimenters on Electricity in our time who have largely
+contributed to the “Curiosities of Science,” Andrew Crosse is entitled
+to special notice. In his school-days he became greatly attached to the
+study of electricity; and on settling on his paternal estate, Fyne
+Court, on the Quantock Hills in Somersetshire, he there devoted himself
+to chemistry, mineralogy, and electricity, pursuing his experiments
+wholly independently of theories, and searching only for facts. In
+Holwell Cavern, near his residence, he observed the sides and the roof
+covered with Arragonite crystallisations, when his observations led
+him to conclude that the crystallisations were the effects, at least
+to some extent, of electricity. This induced him to make the attempt
+to form artificial crystals by the same means, which he began in 1807.
+He took some water from the cave, filled a tumbler, and exposed it to
+the action of a voltaic battery excited by water alone, letting the
+platinum-wires of the battery fall on opposite sides of the tumbler
+from the opposite poles of the battery. After ten days’ constant
+action, he produced crystals of carbonate of lime; and on repeating
+the experiment in the dark, he produced them in six days. Thus Mr.
+Crosse simulated in his laboratory one of the hitherto most mysterious
+processes of nature.
+
+He pursued this line of research for nearly thirty years at Fyne Court,
+where his electrical-room and laboratory were on an enormous scale:
+the apparatus had cost some thousands of pounds, and the house was
+nearly full of furnaces. He carried an insulated wire above the tops
+of the trees around his house to the length of a mile and a quarter,
+afterwards shortened to 1800 feet. By this wire, which was brought
+into connection with the apparatus in a chamber, he was enabled to see
+continually the changes in the state of the atmosphere, and could use
+the fluid so collected for a variety of purposes. In 1816, at a meeting
+of country gentlemen, he prophesied that, “by means of electrical
+agency, we shall be able to communicate our thoughts simultaneously
+with the uttermost ends of the earth.” Still, though he foresaw
+the powers of the medium, he did not make any experiments in that
+direction, but confined himself to the endeavour to produce crystals
+of various kinds. He ultimately obtained forty-one mineral crystals,
+or minerals uncrystallised, in the form in which they are produced by
+nature, including one sub-sulphate of copper--an entirely new mineral,
+neither found in nature nor formed by art previously. His belief was
+that even diamonds might be produced in this way.
+
+Mr. Crosse worked alone in his retreat until 1836, when, attending
+the meeting of the British Association at Bristol, he was induced to
+explain his experiments, for which he was highly complimented by Dr.
+Buckland, Dr. Dalton, Professor Sedgwick, and others.[51]
+
+Shortly after Mr. Crosse’s return to Fyne Court, while pursuing his
+experiments for forming crystals from a highly caustic solution out
+of contact with atmospheric air, he was greatly surprised by the
+appearance of an insect. Black flint, burnt to redness and reduced to
+powder, was mixed with carbonate of potash, and exposed to a strong
+heat for fifteen minutes; and the mixture was poured into a black-lead
+crucible in an air furnace. It was reduced to powder while warm,
+mixed with boiling water, kept boiling for some minutes, and then
+hydrochloric acid was added to supersaturation. After being exposed
+to voltaic action for twenty-six days, a perfect insect of the Acari
+tribe made its appearance, and in the course of a few weeks about a
+hundred more. The experiment was repeated in other chemical fluids
+with the like results; and Mr. Weeks of Sandwich afterwards produced
+the Acari inferrocyanerret of potassium. The Acarus of Mr. Crosse was
+found to contribute a new species of that genus, nearly approaching
+the Acari found in cheese and flour, or more nearly, Hermann’s _Acarus
+dimidiatus_.
+
+This discovery occasioned great excitement. The possibility was denied,
+though Mr. Faraday is said to have stated in the same year that he had
+seen similar appearances in his own electrical experiments. Mr. Crosse
+was now accused of impiety and aiming at creation, to which attacks he
+thus replied:
+
+  As to the appearance of the acari under long-continued electrical
+  action, I have never in thought, word, or deed given any one a
+  right to suppose that I considered them as a creation, or even as a
+  formation, from inorganic matter. To create is to form a something
+  out of a nothing. To annihilate is to reduce that something to
+  a nothing. Both of these, of course, can only be the attributes
+  of the Almighty. In fact, I can assure you most sacredly that I
+  have never dreamed of any theory sufficient to account for their
+  appearance. I confess that I was not a little surprised, and am so
+  still, and quite as much as I was when the acari made their first
+  appearance. Again, I have never claimed any merit as attached to
+  these experiments. It was a matter of chance; I was looking for
+  silicious formations, and animal matter appeared instead.
+
+These Acari, if removed from their birthplace, lived and propagated;
+but uniformly died on the first recurrence of frost, and were entirely
+destroyed if they fell back into the fluid whence they arose.
+
+One of Mr. Crosse’s visitors thus describes the vast electrical room at
+Fyne Court:
+
+  Here was an immense number of jars and gallipots, containing fluids
+  on which electricity was operating for the production of crystals.
+  But you are startled in the midst of your observations by the smart
+  crackling sound that attends the passage of the electrical spark;
+  you hear also the rumbling of distant thunder. The rain is already
+  plashing in great drops against the glass, and the sound of the
+  passing sparks continues to startle your ear; you see at the window
+  a huge brass conductor, with a discharging rod near it passing into
+  the floor, and from the one knob to the other sparks are leaping
+  with increasing rapidity and noise, every one of which would kill
+  twenty men at one blow, if they were linked together hand in hand
+  and the spark sent through the circle. From this conductor wires
+  pass off without the window, and the electric fluid is conducted
+  harmlessly away. Mr. Crosse approached the instrument as boldly as
+  if the flowing stream of fire were a harmless spark. Armed with
+  his insulated rod, he sent it into his batteries: having charged
+  them, he showed how wire was melted, dissipated in a moment, by its
+  passage; how metals--silver, gold, and tin--were inflamed and burnt
+  like paper, only with most brilliant hues. He showed you a mimic
+  aurora and a falling-star, and so proved to you the cause of those
+  beautiful phenomena.
+
+Mr. Crosse appears to have produced in all “about 200 varieties of
+minerals, exactly resembling in all respects similar ones found in
+nature.” He tried also a new plan of extracting gold from its ores
+by an electrical process, which succeeded, but was too expensive
+for common use. He was in the habit of saying that he could, like
+Archimedes, move the world “if he were able to construct a battery at
+once cheap, powerful, and durable.” His process of extracting metals
+from their ores has been patented. Among his other useful applications
+of electricity are the purifying by its means of brackish or sea-water,
+and the improving bad wine and brandy. He agreed with Mr. Quekett
+in thinking that it is by electrical action that silica and other
+mineral substances are carried into and assimilated by plants. Negative
+electricity Mr. Crosse found favourable to no plants except fungi;
+and positive electricity he ascertained to be injurious to fungi, but
+favourable to every thing else.
+
+Mr. Crosse died in 1855. His widow has published a very interesting
+volume of _Memorials_ of the ingenious experimenter, from which we
+select the following:
+
+  On one occasion Mr. Crosse kept a pair of soles under the electric
+  action for three months; and at the end of that time they were
+  sent to a friend, whose domestics knew nothing of the experiment.
+  Before the cook dressed them, her master asked her whether she
+  thought they were fresh, as he had some doubts. She replied that
+  she was sure they were fresh; indeed, she said she could swear
+  that they were alive yesterday! When served at table they appeared
+  like ordinary fish; but when the family attempted to eat them,
+  they were found to be perfectly tasteless--the electric action had
+  taken away all the essential oil, leaving the fish unfit for food.
+  However, the process is exceedingly useful for keeping fish, meat,
+  &c. fresh and _good_ for ten days or a fortnight. I have never
+  heard a satisfactory explanation of the cause of the antiseptic
+  power communicated to water by the passage of the electric current.
+  Whether ozone has not something to do with it, may be a question.
+  The same effect is produced whichever two dissimilar metals are
+  used.
+
+
+
+
+The Electric Telegraph.
+
+
+ANTICIPATIONS OF THE ELECTRIC TELEGRAPH.
+
+The great secret of ubiquity, or at least of instantaneous
+transmission, has ever exercised the ingenuity of mankind in various
+romantic myths; and the discovery of certain properties of the
+loadstone gave a new direction to these fancies.
+
+The earliest anticipation of the Electric Telegraph of this purely
+fabulous character forms the subject of one of the _Prolusiones
+Academicæ_ of the learned Italian Jesuit Strada, first published at
+Rome in the year 1617. Of this poem a free translation appeared in
+1750. Strada’s fancy was this: “There is,” he supposes, “a species of
+loadstone which possesses such virtue, that if two needles be touched
+with it, and then balanced on separate pivots, and the one be turned in
+a particular direction, the other will sympathetically move parallel
+to it. He then directs each of these needles to be poised and mounted
+parallel on a dial having the letters of the alphabet arranged round
+it. Accordingly, if one person has one of the dials, and another the
+other, by a little pre-arrangement as to details a correspondence can
+be maintained between them at any distance by simply pointing the
+needles to the letters of the required words. Strada, in his poetical
+reverie, dreamt that some such sympathy might one day be found to hold
+up the Magnesian Stone.”
+
+Strada’s conceit seems to have made a profound impression on the
+master-minds of the day. His poem is quoted in many works of the
+seventeenth and eighteenth centuries; and Bishop Wilkins, in his book
+on Cryptology, is strangely afraid lest his readers should mistake
+Strada’s fancy for fact. Wilkins writes: “This invention is altogether
+imaginary, having no foundation in any real experiment. You may see it
+frequently confuted in those that treat concerning magnetical virtues.”
+
+Again, Addison, in the 241st No. of the _Spectator_, 1712, describes
+Strada’s “Chimerical correspondence,” and adds that, “if ever this
+invention should be revived or put in practice,” he “would propose
+that upon the lover’s dial-plate there should be written not only the
+four-and-twenty letters, but several entire words which have always a
+place in passionate epistles, as flames, darts, die, language, absence,
+Cupid, heart, eyes, being, drown, and the like. This would very much
+abridge the lover’s pains in this way of writing a letter, as it would
+enable him to express the most useful and significant words with a
+single touch of the needle.”
+
+After Strada and his commentators comes Henry Van Etten, who shows how
+“Claude, being at Paris, and John at Rome, might converse together, if
+each had a needle touched by a stone of such virtue that as one moved
+itself at Paris the other should be moved at Rome:” he adds, “it is
+a fine invention, but I do not think there is a magnet in the world
+which has such virtue; besides, it is inexpedient, for treasons would
+be too frequent and too much protected. (_Recréations Mathématiques_:
+see 5th edition, Paris, 1660, p. 158.) Sir Thomas Browne refers
+to this “conceit” as “excellent, and, if the effect would follow,
+somewhat divine;” but he tried the two needles touched with the same
+loadstone, and placed in two circles of letters, “one friend keeping
+one and another the other, and agreeing upon an hour when they will
+communicate,” and found the tradition a failure that, “at what distance
+of place soever, when one needle shall be removed unto any letter, the
+other, by a wonderful sympathy, will move unto the same.” (See _Vulgar
+Errors_, book ii. ch. iii.)
+
+Glanvill’s _Vanity of Dogmatizing_, a work published in 1661, however,
+contains the most remarkable allusion to the prevailing telegraphic
+fancy. Glanvill was an enthusiast, and he clearly predicts the
+discovery and general adoption of the electric telegraph. “To confer,”
+he says, “at the distance of the Indies by sympathetic conveyance may
+be as usual to future times as to us in a literary correspondence.” By
+the word “sympathetic” he evidently intended to convey magnetic agency;
+for he subsequently treats of “conference at a distance by impregnated
+needles,” and describes the device substantially as it is given by Sir
+Thomas Browne, adding, that though it did not then answer, “by some
+other such way of magnetic efficiency it may hereafter with success be
+attempted, when magical history shall be enlarged by riper inspection;
+and ’tis not unlikely but that present discoveries might be improved
+to the performance.” This may be said to close the most speculative or
+mythical period in reference to the subject of electro-telegraphy.
+
+Electricians now began to be sedulous in their experiments upon the
+new force by friction, then the only known method of generating
+electricity. In 1729, Stephen Gray, a pensioner of the Charter-house,
+contrived a method of making electrical signals through a wire 765
+feet long; yet this most important experiment did not excite much
+attention. Next Dr. Watson, of the Royal Society, experimented on the
+possibility of transmitting electricity through a large circuit from
+the simple fact of Le Monnier’s account of his feeling the stroke
+of the electrified fires through two of the basins of the Tuileries
+(which occupy nearly an acre), by means of an iron chain lying upon
+the ground and stretched round half their circumference. In 1745, Dr.
+Watson, assisted by several members of the Royal Society, made a series
+of experiments to ascertain how far electricity could be conveyed by
+means of conductors. “They caused the shock to pass across the Thames
+at Westminster Bridge, the circuit being completed by making use of the
+river for one part of the chain of communication. One end of the wire
+communicated with the coating of a charged phial, the other being held
+by the observer, who in his other hand held an iron rod which he dipped
+into the river. On the opposite side of the river stood a gentleman,
+who likewise dipped an iron rod in the river with one hand, and in the
+other held a wire the extremity of which might be brought into contact
+with the wire of the phial. Upon making the discharge, the shock was
+felt simultaneously by both the observers.” (_Priestley’s History of
+Electricity._) Subsequently the same parties made experiments near
+Shooter’s Hill, when the wires formed a circuit of four miles, and
+conveyed the shock with equal facility,--“a distance which without
+trial,” they observed, “was too great to be credited.”[52] These
+experiments in 1747 established two great principles: 1, that the
+electric current is transmissible along nearly two miles and a half of
+iron wire; 2, that the electric current may be completed by burying the
+poles in the earth at the above distance.
+
+In the following year, 1748, Benjamin Franklin performed his celebrated
+experiments on the banks of the Schuylkill, near Philadelphia; which
+being interrupted by the hot weather, they were concluded by a picnic,
+when spirits were fired by an electric spark sent through a wire in the
+river, and a turkey was killed by the electric shock, and roasted by
+the electric jack before a fire kindled by the electrified bottle.
+
+In the year 1753, there appeared in the _Scots’ Magazine_, vol. xv.,
+definite proposals for the construction of an electric telegraph,
+requiring as many conducting wires as there are letters in the
+alphabet; it was also proposed to converse by chimes, by substituting
+bells for the balls. A similar system of telegraphing was next invented
+by Joseph Bozolus, a Jesuit, at Rome; and next by the great Italian
+electrician Tiberius Cavallo, in his treatise on Electricity.
+
+In 1787, Arthur Young, when travelling in France, saw a model working
+telegraph by M. Lomond: “You write two or three words on a paper,” says
+Young; “he takes it with him into a room, and turns a machine enclosed
+in a cylindrical case, at the top of which is an electrometer--a
+small fine pith-ball; a wire connects with a similar cylinder and
+electrometer in a distant apartment; and his wife, by remarking the
+corresponding motions of the ball, writes down the words they indicate:
+from which it appears that he has formed an alphabet of motions. As the
+length of the wire makes no difference in the effect, a correspondence
+might be carried on at any distance. Whatever the use may be, the
+invention is beautiful.”
+
+We now reach a new epoch in the scientific period--the discovery of the
+Voltaic Pile. In 1794, according to _Voigt’s Magazine_, Reizen made
+use of the electric spark for the telegraph; and in 1798 Dr. Salva
+of Madrid constructed a similar telegraph, which the Prince of Peace
+subsequently exhibited to the King of Spain with great success.
+
+In 1809, Soemmering exhibited a telegraphic apparatus worked by
+galvanism before the Academy of Sciences at Munich, in which the mode
+of signalling consisted in the development of gas-bubbles from the
+decomposition of water placed in a series of glass tubes, each of which
+denoted a letter of the alphabet. In 1813, Mr. Sharpe, of Doe Hill near
+Alfreton, devised a _voltaic_-electric telegraph, which he exhibited to
+the Lords of the Admiralty, who spoke approvingly of it, but declined
+to carry it into effect. In the following year, Soemmering exhibited a
+_voltaic_-electric telegraph of his own construction, which, however,
+was open to the objection of there being as many wires as signs or
+letters of the alphabet.
+
+The next invention is of much greater importance. Upon the suggestion
+of Cavallo, already referred to, Francis Ronalds constructed a perfect
+electric telegraph, employing frictional electricity notwithstanding
+Volta’s discoveries had been known in England for sixteen years. This
+telegraph was exhibited at Hammersmith in 1816:[53] it consisted of
+a single insulated wire, the indication being by pith-balls in front
+of a dial. When the wire was charged, the balls were divergent, but
+collapsed when the wire was discharged; at the same time were employed
+two clocks, with lettered discs for the signals. “If, as Paley asserts
+(and Coleridge denies), ‘he alone discovers who proves,’ Ronalds is
+entitled to the appellation of the first discoverer of an efficient
+electric telegraph.” (_Saturday Review_, No. 147[54]) Nevertheless
+the Government of the day refused to avail itself of this admirable
+contrivance.
+
+In 1819, Oersted made his great discovery of the deflection, by a
+current of electricity, of a magnetic needle at right angles to such
+current. Dr. Hamel of St. Petersburg states that Baron Schilling was
+the first to apply Oersted’s discovery to telegraphy; Ampère had
+previously suggested it, but his plan was very complicated, and Dr.
+Hamel maintains that Schilling first realised the idea by actually
+producing an electro-magnetic telegraph simpler in construction
+than that which Ampère had _imagined_. In 1836, Professor Muncke of
+Heidelberg, who had inspected Schilling’s telegraphic apparatus,
+explained the same to William Fothergill Cooke, who in the following
+year returned to England, and subsequently, with Professor Wheatstone,
+laboured simultaneously for the introduction of the electro-magnetic
+telegraph upon the English railways; the first patent for which was
+taken out in the joint names of these two gentlemen.
+
+In 1844, Professor Wheatstone, with one of his telegraphs, formed a
+communication between King’s College and the lofty shot-tower on the
+opposite bank of the Thames: the wire was laid along the parapets of
+the terrace of Somerset House and Waterloo Bridge, and thence to the
+top of the tower, about 150 feet high, where a telegraph was placed;
+the wire then descended, and a plate of zinc attached to its extremity
+was plunged into the mud of the river, whilst a similar plate attached
+to the extremity at the north side was immersed in the water. The
+circuit was thus completed by the entire breadth of the Thames, and the
+telegraph acted as well as if the circuit were entirely metallic.
+
+Shortly after this experiment, Professor Wheatstone and Mr. Cooke laid
+down the first working electric telegraph on the Great Western Railway,
+from Paddington to Slough.
+
+
+ELECTRIC GIRDLE FOR THE EARTH.
+
+One of our most profound electricians is reported to have exclaimed:
+“Give me but an unlimited length of wire, with a small battery, and I
+will girdle the universe with a sentence in forty minutes.” Yet this is
+no vain boast; for so rapid is the transition of the electric current
+along the line of the telegraph wire, that, supposing it were possible
+to carry the wires eight times round the earth, the transit would
+occupy but _one second of time_!
+
+
+CONSUMPTION OF THE ELECTRIC TELEGRAPH.
+
+It is singular to see how this telegraphic agency is measured by the
+chemical consumption of zinc and acid. Mr. Jones (who has written a
+work upon the Electric Telegraphs of America) estimates that to work
+12,000 miles of telegraph about 3000 zinc cups are used to hold the
+acid: these weigh about 9000 lbs., and they undergo decomposition by
+the galvanic action in about six months, so that 18,000 lbs. of zinc
+are consumed in a year. There are also about 3600 porcelain cups to
+contain nitric acid; it requires 450 lbs. of acid to charge them once,
+and the charge is renewed every fortnight, making about 12,000 lbs. of
+nitric acid in a year.
+
+
+TIME LOST IN ELECTRIC MESSAGES.
+
+Although it may require an hour, or two or three hours, to transmit
+a telegraphic message to a distant city, yet it is the mechanical
+adjustment by the sender and receiver which really absorbs this time;
+the actual transit is practically instantaneous, and so it would be
+from here to the antipodes, so far as the current itself is concerned.
+
+
+THE ELECTRIC TELEGRAPH IN ASTRONOMY AND THE DETERMINATION OF LONGITUDE.
+
+The Electric Telegraph has become an instrument in the hands of the
+astronomer for determining the difference of longitude between two
+observatories. Thus in 1854 the difference of longitude between London
+and Paris was determined within a limit of error which amounted barely
+to a quarter of a second. The sudden disturbances of the magnetic
+needle, when freely suspended, which seem to take place simultaneously
+over whole continents, if not over the whole globe, from some
+unexplained cause, are pointed out as means by which the differences of
+longitude between the magnetic observatories may possibly be determined
+with greater precision than by any yet known method.
+
+So long ago as 1839 Professor Morse suggested some experiments for
+the determination of Longitudes; and in June 1844 the difference of
+longitude between Washington and Baltimore was determined by electric
+means under his direction. Two persons were stationed at these two
+towns, with clocks carefully adjusted to the respective spots; and
+a telegraphic signal gave the means of comparing the two clocks
+at a given instant. In 1847 the relative longitudes of New York,
+Philadelphia, and Washington were determined by means of the electric
+telegraph by Messrs. Keith, Walker, and Loomis.
+
+
+NON-INTERFERENCE OF GALVANIC WAVES ON THE SAME WIRE.
+
+One of the most remarkable facts in the economy of the telegraph is,
+that the line, when connected with a battery in action, propagates
+the hydro-galvanic waves in either direction without interference. As
+several successive syllables of sound may set out in succession from
+the same place, and be on their way at the same time, to a listener at
+a distance, so also, where the telegraph-line is long enough, several
+waves may be on their way from the signal station before the first one
+reaches the receiving station; two persons at a distance may pronounce
+several syllables at the same time, and each hear those emitted by the
+other. So, on a telegraph-line of two or three thousand miles in length
+in the air, and the same in the ground, two operators may at the same
+instant commence a series of several dots and lines, and each receive
+the other’s writings, though the waves have crossed each other on the
+way.
+
+
+EFFECT OF LIGHTNING UPON THE ELECTRIC TELEGRAPH.
+
+In the storm of Sunday April 2, 1848, the lightning had a very
+considerable effect on the wires of the electric telegraph,
+particularly on the line of railway eastward from Manchester to
+Normanton. Not only were the needles greatly deflected, and their power
+of answering to the handles considerably weakened, but those at the
+Normanton station were found to have had their poles reversed by some
+action of the electric fluid in the atmosphere. The damage, however,
+was soon repaired, and the needles again put in good working order.
+
+
+ELECTRO-TELEGRAPHIC MESSAGE TO THE STARS.
+
+The electric fluid travels at the mean rate of 20,000 miles in a
+second under ordinary circumstances; therefore, if it were possible to
+establish a telegraphic communication with the star 61 Cygni, it would
+require ninety years to send a message there.
+
+Professor Henderson and Mr. Maclear have fully confirmed the annual
+parallax of α Centauri to amount to a second of arc, which gives about
+twenty billions of miles as its distance from our system; a ray of
+light would arrive from α Centauri to us in little more than three
+years, and a telegraphic despatch would arrive there in thirty years.
+
+
+THE ATLANTIC TELEGRAPH.
+
+The telegraphic communication between England and the United States
+is so grand a conception, that it would be impossible to detail its
+scientific and mechanical relations within the limits of the present
+work. All that we shall attempt, therefore, will be to glance at a few
+of the leading operations.
+
+In the experiments made before the Atlantic Telegraph was finally
+decided on, 2000 miles of subterranean and submarine telegraphic wires,
+ramifying through England and Ireland and under the waters of the
+Irish Sea, were specially connected for the purpose; and through this
+distance of 2000 miles 250 distinct signals were recorded and printed
+in one minute.
+
+First, as to the _Cable_. In the ordinary wires by the side of
+a railway the electric current travels on with the speed of
+lightning--uninterrupted by the speed of lightning; but when a wire
+is encased in gutta-percha, or any similar covering, for submersion
+in the sea, new forces come into play. The electric excitement of the
+wire acts by induction, through the envelope, upon the particles of
+water in contact with that envelope, and calls up an electric force
+of an opposite kind. There are two forces, in fact, pulling against
+each other through the gutta-percha as a neutral medium,--that is,
+the electricity in the wire, and the opposite electricity in the film
+of water immediately surrounding the cable; and to that extent the
+power of the current in the enclosed wire is weakened. A submarine
+cable, when in the water, is virtually _a lengthened-out Leyden jar_;
+it transmits signals while being charged and discharged, instead of
+merely allowing a stream to flow evenly along it: it is a _bottle_
+for holding electricity rather than a _pipe_ for carrying it; and
+this has to be filled for every time of using. The wire being carried
+underground, or through the water, the speed becomes quite measurable,
+say a thousand miles in a second, instead of two hundred thousand,
+owing to the retardation by induced or retrograde currents. The energy
+of the currents and the quality of the wire also affect the speed.
+Until lately it was supposed that the wire acts only as a _conductor_
+of electricity, and that a long wire must produce a weaker effect than
+a short one, on account of the consequent attenuation of the electrical
+influence; but it is now known that, the cable being a _reservoir_ as
+well as a conductor, its electrical supply is increased in proportion
+to its length.
+
+The electro-magnetic current is employed, since it possesses a treble
+velocity of transmission, and realises consequently _a threefold
+working speed_ as compared with simple voltaic electricity. Mr. Wildman
+Whitehouse has determined by his ingenious apparatus that the speed
+of the voltaic current might be raised under special circumstances
+to 1800 miles per second; but that of the induced current, or the
+electro-magnetic, might be augmented to 6000 miles per second.
+
+Next as to a _Quantity Battery_ employed in these investigations. To
+effect a charge, and transmit a current through some thousand miles of
+the Atlantic Cable, Mr. Whitehouse had a piece of apparatus prepared
+consisting of twenty-five pairs of zinc and silver plates about the
+20th part of a square inch large, and the pairs so arranged that
+they would hold a drop of acidulated water or brine between them. On
+charging this Lilliputian battery by dipping the plates in salt and
+water, messages were sent from it through a thousand miles of cable
+with the utmost ease; and not only so,--pair after pair was dropped
+out from the series, the messages being still sent on with equal
+facility, until at last only a single pair, charged by one single drop
+of liquid, was used. Strange to say, with this single pair and single
+drop distinct signals were effected through the thousand miles of the
+cable! Each signal was registered at the end of the cable in less than
+three seconds of time.
+
+The entire length of wire, iron and copper, spun into the cable amounts
+to 332,500 miles, a length sufficient to engirdle the earth thirteen
+times. The cable weighs from 19 cwt. to a ton per mile, and will bear a
+strain of 5 tons.
+
+The _Perpetual Maintenance Battery_, for working the cable at the
+bottom of the sea, consists of large plates of platinated silver and
+amalgamated zinc, mounted in cells of gutta-percha. The zinc plates in
+each cell rest upon a longitudinal bar at the bottom, and the silver
+plates hang upon a similar bar at the top of the cell; so that there
+is virtually but a single stretch of silver and a single stretch of
+zinc in operation. Each of the ten cells contains 2000 square inches
+of acting surface; and the combination is so powerful, that when the
+broad strips of copper-plate which form the polar extensions are
+brought into contact or separated, brilliant flashes are produced,
+accompanied by a loud crackling sound. The points of large pliers
+are made red-hot in five seconds when placed between them, and even
+screws burn with vivid scintillation. The cost of maintaining this
+magnificent ten-celled Titan battery at work does not exceed a shilling
+per hour. The voltaic current generated in this battery is not,
+however, the electric stream to be sent across the Atlantic, but is
+only the primary power used to call up and stimulate the energy of a
+more speedy traveller by a complicated apparatus of “Double Induction
+Coils.” Nor is the transmission-current generated in the inner wire
+of the double induction coil,--and which becomes weakened when it has
+passed through 1800 or 1900 miles,--set to work to print or record the
+signals transmitted. This weakened current merely opens and closes the
+outlet of a fresh battery, which is to do the printing labour. This
+relay-instrument (as it is called), which consists of a temporary and
+permanent magnet, is so sensitive an apparatus, that it may be put in
+action by a fragment of zinc and a sixpence pressed against the tongue.
+
+The attempts to lay the cable in August 1857 failed through stretching
+it so tightly that it snapped and went to the bottom, at a depth of
+12,000 feet, forty times the height of St. Paul’s.
+
+This great work was resumed in August 1858; and on the 5th the first
+signals were received through _two thousand and fifty miles_ of the
+Atlantic Cable. And it is worthy of remark, that just 111 years
+previously, on the 5th of August 1747, Dr. Watson astonished the
+scientific world by practically proving that the electric current could
+be transmitted through a _wire hardly two miles and a half long_.[55]
+
+
+
+
+Miscellanea.
+
+
+HOW MARINE CHRONOMETERS ARE RATED AT THE ROYAL OBSERVATORY, GREENWICH.
+
+The determination of the Longitude at Sea requires simply accurate
+instruments for the measurement of the positions of the heavenly
+bodies, and one or other of the two following,--either perfectly
+correct watches--or chronometers, as they are now called--or perfectly
+accurate tables of the lunar motions.
+
+So early as 1696 a report was spread among the members of the Royal
+Society that Sir Isaac Newton was occupied with the problem of finding
+the longitude at sea; but the rumour having no foundation, he requested
+Halley to acquaint the members “that he was not about it.”[56] (_Sir
+David Brewster’s Life of Newton._)
+
+In 1714 the legislature of Queen Anne passed an Act offering a reward
+of 20,000_l._ for the discovery of the longitude, the problem being
+then very inaccurately solved for want of good watches or lunar tables.
+About the year 1749, the attention of the Royal Society was directed
+to the improvements effected in the construction of watches by John
+Harrison, who received for his inventions the Copley Medal. Thus
+encouraged, Harrison continued his labours with unwearied diligence,
+and produced in 1758 a timekeeper which was sent for trial on a voyage
+to Jamaica. After 161 days the error of the instrument was only 1m
+5s, and the maker received from the nation 5000_l._ The Commissioners
+of the Board of Longitude subsequently required Harrison to construct
+under their inspection chronometers of a similar nature, which were
+subjected to trial in a voyage to Barbadoes, and performed with such
+accuracy, that, after having fully explained the principle of their
+construction to the commissioners, they awarded him 10,000_l._ more;
+at the same time Euler of Berlin and the heirs of Mayer of Göttingen
+received each 3000_l._ for their lunar tables.
+
+  The account of the trial of Harrison’s watch is very interesting.
+  In April 1766, by desire of the Commissioners of the Board, the
+  Lords of the Admiralty delivered the watch into the custody of
+  the Astronomer-Royal, the Rev. Dr. Nevil Maskelyne. It was then
+  placed at the Royal Observatory at Greenwich, in a box having two
+  different locks, fixed to the floor or wainscot, with a plate of
+  glass in the lid of the box, so that it might be compared as often
+  as convenient with the regulator and the variation set down. The
+  form observed by Mr. Harrison in winding up the watch was exactly
+  followed; and an officer of Greenwich Hospital attended every day,
+  at a stated hour, to see the watch wound up, and its comparison
+  with the regulator entered. A key to one of the locks was kept at
+  the Hospital for the use of the officer, and the other remained
+  at the Observatory for the use of the Astronomer-Royal or his
+  assistant.
+
+  The watch was then tried in various positions till the beginning
+  of July; and from thence to the end of February following in a
+  horizontal position with its face upwards.
+
+  The variation of the watch was then noted down, and a register was
+  kept of the barometer and thermometer; and the time of comparing
+  the same with the regulator was regularly kept, and attested by
+  the Astronomer-Royal or his assistant and such of the officers as
+  witnessed the winding-up and comparison of the watch.
+
+  Under these conditions Harrison’s watch was received by the
+  Astronomer-Royal at the Admiralty on May 5, 1766, in the presence
+  of Philip Stephens, Esq., Secretary of the Admiralty; Captain
+  Baillie, of the Royal Hospital, Greenwich; and Mr. Kendal the
+  watchmaker, who accompanied the Astronomer-Royal to Greenwich, and
+  saw the watch started and locked up in the box provided for it. The
+  watch was then compared with the transit clock daily, and wound up
+  in the presence of the officer of Greenwich Hospital. From May 5 to
+  May 17 the watch was kept in a horizontal position with its face
+  upwards; from May 18 to July 6 it was tried--first inclined at an
+  angle of 20° to the horizon, with the face upwards, and the hours
+  12, 6, 3, and 9, highest successively; then in a vertical position,
+  with the same hours highest in order; lastly, in a horizontal
+  position with the face downwards. From July 16, 1766, to March 4,
+  1767, it was always kept in a horizontal position with its face
+  upwards, lying upon the same cushion, and in the same box in which
+  Mr. Harrison had kept it in the voyage to Barbadoes.
+
+  From the observed transits of the sun over the meridian, according
+  to the time of the regulator of the Observatory, together with
+  the attested comparisons of Mr. Harrison’s watch with the transit
+  clock, the watch was found too fast on several days as follows:
+
+                                h.  m.   s.
+    1766. May 6      too fast   0   0  16·2
+          May 17        ”       0   3  51·8
+          July 6        ”       0  14  14·0
+          Aug. 6        ”       0  23  58·4
+          Sept. 17      ”       0  32  15·6
+          Oct. 29       ”       0  42  20·9
+          Dec. 10       ”       0  54  46·8
+    1767. Jan. 21       ”       1   0  28·6
+          March 4       ”       1  11  23·0
+
+  From May 6, which was the day after the watch arrived at the Royal
+  Observatory, to March 4, 1767, there were six periods of six weeks
+  each in which the watch was tried in a horizontal position; when
+  the gaining in these several periods was as follows:
+
+    During the first 6 weeks it gained 13m 20s, answering to 3° 20′
+    of longitude.
+
+    In the 2d period of 6
+      weeks (from Aug. 6 to        ”    8  17       ”        2   4
+      Sept. 17)
+
+    In the 3d period (from         ”   10   5       ”        2  31
+      Sept. 17 to Oct. 29)
+
+    In the 4th period (from        ”   12  26       ”        3   6
+      Oct. 29 to Dec. 20)
+
+    In the 5th period (from        ”    5  42       ”        1  25
+      Dec. 20 to Jan. 21)
+
+    In the 6th period (from        ”   10  54       ”        2  43
+      Jan. 21 to Mar. 4)
+
+It was thence concluded that Mr. Harrison’s watch could not be depended
+upon to keep the longitude within a West-India voyage of six weeks, nor
+to keep the longitude within half a degree for more than a fortnight;
+and that it must be kept in a place where the temperature was always
+some degrees above freezing.[57] (However, Harrison’s watch, which was
+made by Mr. Kendal subsequently, succeeded so completely, that after it
+had been round the world with Captain Cook, in the years 1772-1775, the
+second 10,000_l._ was given to Harrison.)
+
+In the Act of 12th Queen Anne, the comparison of chronometers was not
+mentioned in reference to the Observatory duties; but after this time
+they became a serious charge upon the Observatory, which, it must be
+admitted, is by far the best place to try chronometers: the excellence
+of the instruments, and the frequent observations of the heavenly
+bodies over the meridian, will always render the rate of going of the
+Observatory clock better known than can be expected of the clock in
+most other places.
+
+After Mr. Harrison’s watch was tried, some watches by Earnshaw, Mudge,
+and others, were rated and examined by the Astronomer-Royal.
+
+At the Royal Observatory, Greenwich, there are frequently above 100
+chronometers being rated, and there have been as many as 170 at one
+time. They are rated daily by two observers, the process being as
+follows. At a certain time every day two assistants in charge repair
+to the chronometer-room, where is a time-piece set to true time; one
+winds up each with its own key, and the second follows after some
+little time and verifies the fact that each is wound. One assistant
+then looks at each watch in succession, counting the beats of the clock
+whilst he compares the chronometer by the eye; and in the course of a
+few seconds he calls out the second shown by the chronometer when the
+clock is at a whole minute. This number is entered in a book by the
+other assistant, and so on till all the chronometers are compared.
+Then the assistants change places, the second comparing and the first
+writing down. From these daily comparisons the daily rates are deduced,
+by which the goodness of the watch is determined. The errors are of
+two classes--that of general bad workmanship, and that of over or
+under correction for temperature. In the room is an apparatus in which
+the watch may be continually kept at temperatures exceeding 100° by
+artificial heat; and outside the window of the room is an iron cage,
+in which they are subjected to low temperatures. The very great care
+taken with all chronometers sent to the Royal Observatory, as well as
+the perfect impartiality of the examination which each receives, afford
+encouragement to their manufacture, and are of the utmost importance to
+the safety and perfection of navigation.
+
+We have before us now the Report of the Astronomer-Royal on the Rates
+of Chronometers in the year 1854, in which the following are the
+successive weekly sums of the daily rates of the first there mentioned:
+
+    Week ending              secs.
+
+    Jan. 21, loss in the week 2·2
+     ”   28         ”         4·0
+    Feb.  4         ”         1·1
+     ”   11         ”         5·0
+     ”   18         ”         4·9
+     ”   25         ”         5·5
+    Mar.  4         ”         6·0
+     ”   11         ”         6·0
+     ”   18         ”         1·5
+     ”   25         ”         4·5
+    Apr.  1         ”         4·0
+     ”    8         ”         1·5
+     ”   15, gain in the week 0·4
+    Apr. 22,        ”         2·6
+     ”   29, loss in the week 1·4
+    May   6         ”         2·1
+     ”   13         ”         3·0
+     ”   20         ”         5·1
+     ”   27         ”         3·3
+    June  3         ”         2·8
+     ”   10         ”         1·8
+     ”   17         ”         2·0
+     ”   24         ”         3·0
+    July  1         ”         2·5
+     ”    8         ”         1·2
+
+Till February 4 the watch was exposed to the external air outside a
+north window; from February 5 to March 4 it was placed in the chamber
+of a stove heated by gas to a moderate temperature; and from April
+29 to May 20 it was placed in the chamber when heated to a high
+temperature.
+
+The advance in making chronometers since Harrison’s celebrated watch
+was tried at the Royal Observatory, more than ninety years since, may
+be judged by comparing its rates with those above.
+
+
+GEOMETRY OF SHELLS.
+
+There is a mechanical uniformity observable in the description of
+shells of the same species which at once suggests the probability that
+the generating figure of each increases, and that the spiral chamber of
+each expands itself, according to some simple geometrical law common
+to all. To the determination of this law the operculum lends itself,
+in certain classes of shells, with remarkable facility. Continually
+enlarged by the animal, as the construction of its shell advances so as
+to fill up its mouth, the operculum measures the progressive widening
+of the spiral chamber by the progressive stages of its growth.
+
+       *       *       *       *       *
+
+The animal, as he advances in the construction of his shell, increases
+continually his operculum, so as to adjust it to his mouth. He
+increases it, however, not by additions made at the same time all round
+its margin, but by additions made only on one side of it at once. One
+edge of the operculum thus remains unaltered as it is advanced into
+each new position, and placed in a newly-formed section of the chamber
+similar to the last but greater than it.
+
+That the same edge which fitted a portion of the first less section
+should be capable of adjustment so as to fit a portion of the next
+similar but greater section, supposes a geometrical provision in the
+curved form of the chamber of great complication and difficulty. But
+God hath bestowed upon this humble architect the practical skill of
+the learned geometrician; and he makes this provision with admirable
+precision in that curvature of the logarithmic spiral which he gives to
+the section of the shell. This curvature obtaining, he has only to turn
+his operculum slightly round in its own place, as he advances it into
+each newly-formed portion of his chamber, to adapt one margin of it to
+a new and larger surface and a different curvature, leaving the space
+to be filled up by increasing the operculum wholly on the outer margin.
+
+       *       *       *       *       *
+
+Why the Mollusks, who inhabit turbinated and discoid shells, should, in
+the progressive increase of their spiral dwellings, affect the peculiar
+law of the logarithmic spiral, is easily to be understood. Providence
+has subjected the instinct which shapes out each to a rigid uniformity
+of operation.--_Professor Mosely_: _Philos. Trans._ 1838.
+
+
+HYDRAULIC THEORY OF SHELLS.
+
+How beautifully is the wisdom of God developed in shaping out and
+moulding shells! and especially in the particular value of the constant
+angle which the spiral of each species of shell affects,--a value
+connected by a necessary relation with the economy of the material
+of each, and with its stability and the conditions of its buoyancy.
+Thus the shell of the _Nautilus Pompilius_ has, hydrostatically, an
+A-statical surface. If placed with any portion of its surface upon the
+water, it will immediately turn over towards its smaller end, and rest
+only on its mouth. Those conversant with the theory of floating bodies
+will recognise in this an interesting property.--_Ibid._
+
+
+SERVICES OF SEA-SHELLS AND ANIMALCULES.
+
+Dr. Maury is disposed to regard these beings as having much to do in
+maintaining the harmonies of creation, and the principles of the most
+admirable compensation in the system of oceanic circulation. “We may
+even regard them as regulators, to some extent, of climates in parts
+of the earth far removed from their presence. There is something
+suggestive both of the grand and the beautiful in the idea that while
+the insects of the sea are building up their coral islands in the
+perpetual summer of the tropics, they are also engaged in dispensing
+warmth to distant parts of the earth, and in mitigating the severe cold
+of the polar winter.”
+
+
+DEPTH OF THE PRIMEVAL SEAS.
+
+Professor Forbes, in a communication to the Royal Society, states that
+not only the colour of the shells of existing mollusks ceases to be
+strongly marked at considerable depths, but also that well-defined
+patterns are, with very few and slight exceptions, presented only by
+testacea inhabiting the littoral, circumlittoral, and median zones.
+In the Mediterranean, only one in eighteen of the shells taken from
+below 100 fathoms exhibit any markings of colour, and even the few
+that do so are questionable inhabitants of those depths. Between 30
+and 35 fathoms, the proportion of marked to plain shells is rather
+less than one in three; and between the margin and two fathoms the
+striped or mottled species exceed one-half of the total number. In our
+own seas, Professor Forbes observes that testacea taken from below 100
+fathoms, even when they are individuals of species vividly striped or
+banded in shallower zones, are quite white or colourless. At between
+60 and 80 fathoms, striping and banding are rarely presented by our
+shells, especially in the northern provinces; from 50 fathoms, shallow
+bands, colours, and patterns, are well marked. _The relation of these
+arrangements of colour to the degree of light penetrating the different
+zones of depth_ is a subject well worthy of minute inquiry.
+
+
+NATURAL WATER-PURIFIERS.
+
+Mr. Warrington kept for a whole year twelve gallons of water in a state
+of admirably balanced purity by the following beautiful action:
+
+  In the tank, or aquarium, were two gold fish, six water-snails, and
+  two or three specimens of that elegant aquatic plant _Valisperia
+  sporalis_, which, before the introduction of the water-snails, by
+  its decayed leaves caused a growth of slimy mucus, and made the
+  water turbid and likely to destroy both plants and fish. But under
+  the improved arrangement the slime, as fast as it was engendered,
+  was consumed by the water-snails, which reproduced it in the shape
+  of young snails, which furnished a succulent food to the fish.
+  Meanwhile the _Valisperia_ plants absorbed the carbonic acid
+  exhaled by the respiration of their companions, fixing the carbon
+  in their growing stems and luxuriant blossoms, and refreshing
+  the oxygen (during sunshine in visible little streams) for the
+  respiration of the snails and the fish. The spectacle of perfect
+  equilibrium thus simply maintained between animal, vegetable, and
+  inorganic activity, was strikingly beautiful; and such means might
+  possibly hereafter be made available on a large scale for keeping
+  tanked water sweet and clean.--_Quarterly Review_, 1850.
+
+
+HOW TO IMITATE SEA-WATER.
+
+The demand for Sea-water to supply the Marine Aquarium--now to be
+seen in so many houses--induced Mr. Gosse to attempt the manufacture
+of Sea-water, more especially as the constituents are well known. He
+accordingly took Scheveitzer’s analysis of Sea-water for his guide. In
+one thousand grains of sea-water taken off Brighton, it gave: water,
+964·744; chloride of sodium, 27·059; chloride of magnesium, 3·666;
+chloride of potassium, 9·755; bromide of magnesium, 0·29; sulphate of
+magnesia, 2·295; sulphate of lime, 1·407; carbonate of lime, 0·033:
+total, 999·998. Omitting the bromide of magnesium, the carbonate of
+lime, and the sulphate of lime, as being very small quantities, the
+component parts were reduced to common salt, 3½ oz.; Epsom salts, ¼
+oz.; chloride of magnesium, 200 grains troy; chloride of potassium,
+40 grains troy; and four quarts of water. Next day the mixture was
+filtered through a sponge into a glass jar, the bottom covered with
+shore-pebbles and fragments of stone and fronds of green sea-weed. A
+coating of green spores was soon deposited on the sides of the glass,
+and bubbles of oxygen were copiously thrown off every day under the
+excitement of the sun’s light. In a week Mr. Gosse put in species of
+_Actinia Bowerbankia_, _Cellularia_, _Serpula_, &c. with some red
+sea-weeds; and the whole throve well.
+
+
+VELOCITY OF IMPRESSIONS TRANSMITTED TO THE BRAIN.
+
+Professor Helmholtz of Königsberg has, by the electro-magnetic
+method,[58] ascertained that the intelligence of an impression
+made upon the ends of the nerves in communication with the skin
+is transmitted to the brain with a velocity of about 195 feet per
+second. Arrived at the brain, about one-tenth of a second passes
+before the will is able to give the command to the nerves that certain
+muscles shall execute a certain motion, varying in persons and times.
+Finally, about 1/100th of a second passes after the receipt of the
+command before the muscle is in activity. In all, therefore, from the
+excitation of the sensitive nerves till the moving of the muscle, 1¼
+to 2/10ths of a second are consumed. Intelligence from the great toe
+arrives about 1/30th of a second later than from the ear or the face.
+
+Thus we see that the differences of time in the nervous impressions,
+which we are accustomed to regard as simultaneous, lie near our
+perception. We are taught by astronomy that, on account of the
+time taken to propagate light, we now see what has occurred in the
+fixed stars years ago; and that, owing to the time required for the
+transmission of sound, we hear after we see is a matter of daily
+experience. Happily the distances to be traversed by our sensuous
+perceptions before they reach the brain are so short that we do
+not observe their influence, and are therefore unprejudiced in our
+practical interest. With an ordinary whale the case is perhaps more
+dubious; for in all probability the animal does not feel a wound near
+its tail until a second after it has been inflicted, and requires
+another second to send the command to the tail to defend itself.
+
+
+PHOTOGRAPHS ON THE RETINA.
+
+The late Rev. Dr. Scoresby explained with much minuteness and skill
+the varying phenomena which presented themselves to him after gazing
+intently for some time on strongly-illuminated objects,--as the sun,
+the moon, a red or orange or yellow wafer on a strongly-contrasted
+ground, or a dark object seen in a bright field. The doctor explained,
+upon removing the eyes from the object, the early appearance of the
+picture or image which had been thus “photographed on the Retina,” with
+the photochromatic changes which the picture underwent while it still
+retained its general form and most strongly-marked features; also, how
+these pictures, when they had almost faded away, could at pleasure, and
+for a considerable time, be renewed by rapidly opening and shutting the
+eyes.
+
+
+DIRECT EXPLORATION OF THE INTERIOR OF THE EYE.
+
+Dr. S. Wood of Cincinnati states, that by means of a small double
+convex lens of short focus held near the eye,--that organ looking
+through it at a candle twelve or fifteen feet distant,--there will be
+perceived a large luminous disc, covered with dark and light spots and
+dark streaks, which, after a momentary confusion, will settle down
+into an unchanging picture, which picture is composed of the organs
+or internal parts of the eye. The eye is thus enabled to view its own
+internal organisation, to have a beautiful exhibition of the vessels of
+the cornea, of the distribution of the lachrymas secretions in the act
+of winking, and to see into the nature and cause of _muscæ volitantes_.
+
+
+NATURE OF THE CANDLE-FLAME.
+
+M. Volger has subjected this Flame to a new analysis.
+
+  He finds that the so-called _flame-bud_, a globular blue flaminule,
+  is first produced at the summit of the wick: this is the result
+  of the combustion of carbonic oxide, hydrogen, and carbon, and is
+  surrounded by a reddish-violet halo, the _veil_. The increased
+  heat now gives rise to the actual flame, which shoots forth from
+  the expanding bud, and is then surrounded at its inferior portion
+  only by the latter. The interior consists of a dark gaseous cone,
+  containing the immediate products of the decomposition of the fatty
+  acids, and surrounded by another dark hollow cone, the _inner
+  cap_. Here we already meet with carbon and hydrogen, which have
+  resulted from the process of decomposition; and we distinguish
+  this cone from the inner one by its yielding soot. The _external
+  cap_ constitutes the most luminous portion of the flame, in which
+  the hydrogen is consumed and the carbon rendered incandescent. The
+  surrounding portion is but slightly luminous, deposits no soot,
+  and in it the carbon and hydrogen are consumed.--_Liebig’s Annual
+  Report._
+
+
+HOW SOON A CORPSE DECAYS.
+
+Mr. Lewis, of the General Board of Health, from his examination of the
+contents of nearly 100 coffins in the vaults and catacombs of London
+churches, concludes that the complete decomposition of a corpse, and
+its resolution into its ultimate elements, takes place in a leaden
+coffin with extreme slowness. In a wooden coffin the remains, with the
+exception of the bones, vanish in from two to five years. This period
+depends upon the quality of the wood, and the free access of air to
+the coffins. But in leaden coffins, 50, 60, 80, and even 100 years
+are required to accomplish this. “I have opened,” says Mr. Lewis, “a
+coffin in which the corpse had been placed for nearly a century; and
+the ammoniacal gas formed dense white fumes when brought in contact
+with hydrochloric-acid gas, and was so powerful that the head could
+not remain in it for more than a few seconds at a time.” To render the
+human body perfectly inert after death, it should be placed in a light
+wooden coffin, in a pervious soil, from five to eight feet deep.
+
+
+MUSKET-BALLS FOUND IN IVORY.
+
+The Ceylon sportsman, in shooting elephants, aims at a spot just above
+the proboscis. If he fires a little too low, the ball passes into the
+tusk-socket, causing great pain to the animal, but not endangering
+its life; and it is immediately surrounded by osteo-dentine. It has
+often been a matter of wonder how such bodies should become completely
+imbedded in the substance of the tusk, sometimes without any visible
+aperture; or how leaden bullets become lodged in the solid centre of a
+very large tusk without having been flattened, as they are found by
+the ivory-turner.
+
+  The explanation is as follows: A musket-ball aimed at the head of
+  an elephant may penetrate the thin bony socket and the thinner
+  ivory parietes of the wide conical pulp-cavity occupying the
+  inserted base of the tusk; if the projectile force be there spent,
+  the ball will gravitate to the opposite and lower side of the
+  pulp-cavity. The pulp becomes inflamed, irregular calcification
+  ensues, and osteo-dentine is formed around the ball. The pulp
+  then resumes its healthy state and functions, and coats the
+  osteo-dentine enclosing the ball, together with the root of the
+  conical cavity into which the mass projects, with layers of normal
+  ivory. The hole formed by the ball is soon replaced, and filled
+  up by osteo-dentine, and coated with cement. Meanwhile, by the
+  continued progress of growth, the enclosed ball is pushed forward
+  to the middle of the solid tusk; or if the elephant be young, the
+  ball may be carried forward by growth and wear of the tusk until
+  its base has become the apex, and become finally exposed and
+  discharged by the continual abrasion to which the apex of the tusk
+  is subjected.--_Professor Owen._
+
+
+NATURE OF THE SUN.
+
+To the article at pp. 59-60 should be added the result obtained by Dr.
+Woods of Parsonstown, and communicated to the _Philosophical Magazine_
+for July 1854. Dr. Woods, from photographic experiment, has no doubt
+that the light from the centre of flame acts more energetically than
+that from the edge on a surface capable of receiving its impression;
+and that light from a luminous solid body acts equally powerfully from
+its centre or its edges: wherefore Dr. Woods concludes that, as the
+sun affects a sensitive plate similarly with flame, it is probable its
+light-producing portion is of a similar nature.
+
+  _Note to_ “IS THE HEAT OF THE SUN DECREASING?” _at page 65_.--Dr.
+  Vaughan of Cincinnati has stated to the British Association:
+  “From a comparison of the relative intensity of solar, lunar,
+  and artificial light, as determined by Euler and Wollaston, it
+  appears that the rays of the sun have an illuminating power
+  equal to that of 14,000 candles at a distance of one foot, or
+  of 3500,000000,000000,000000,000000 candles at a distance of
+  95,000,000 miles. It follows that the amount of light which
+  flows from the solar orb could be scarcely produced by the daily
+  combustion of 200 globes of tallow, each equal to the earth in
+  magnitude. A sphere of combustible matter much larger than the
+  sun itself should be consumed every ten years in maintaining its
+  wonderful brilliancy; and its atmosphere, if pure oxygen, would be
+  expended before a few days in supporting so great a conflagration.
+  An illumination on so vast a scale could be kept up only by the
+  inexhaustible magazine of ether disseminated through space, and
+  ever ready to manifest its luciferous properties on large spheres,
+  whose attraction renders it sufficiently dense for the play of
+  chemical affinity. Accordingly suns derive the power of shedding
+  perpetual light, not from their chemical constitution, but from
+  their immense mass and their superior attractive power.”
+
+
+PLANETOIDS.
+
+  +----------------+---------------+-----------+-----------+-----------+
+  |                |               |           |           |    No.    |
+  |                |               |           |           |discovered |
+  |                |    Date of    |           | Place of  |  by each  |
+  |      Name.     |  Discovery.   |Discoverer.| Discovery.|astronomer.|
+  +----------------+---------------+-----------+-----------+-----------+
+  |Mercury, Mars, }|     Known  }  |           |           |           |
+  |Venus, Jupiter,}|    to the  }  |   ...     |    ...    |    --     |
+  |Earth, Saturn, }|   ancients.}  |           |           |           |
+  |   Uranus       |1781, March 13 |W. Herschel| Bath      |    --     |
+  |   Neptune[59]  |1846, Sept. 23 |Galle      | Berlin    |    --     |
+  | 1 Ceres        |1801, Jan. 1   |Piazzi     | Palermo   |     1     |
+  | 2 Pallas       |1802, March 28 |Olbers     | Bremen    |     1     |
+  | 3 Juno         |1804, Sept. 1  |Harding    | Lilienthal|     1     |
+  | 4 Vesta        |1807, March 29 |Olbers     | Bremen    |     2     |
+  | 5 Astræa       |1845, Dec. 8   |Encke      | Driesen   |     1     |
+  | 6 Hebe         |1847, July 1   |Encke      | Driesen   |     2     |
+  | 7 Iris         |1847, August 13|Hind       | London    |     1     |
+  | 8 Flora        |1847, Oct. 18  |Hind       | London    |     2     |
+  | 9 Metis        |1848, April 25 |Graham     | Markree   |     1     |
+  |10 Hygeia       |1849, April 12 |Gasperis   | Naples    |     1     |
+  |11 Parthenope   |1850, May 11   |Gasperis   | Naples    |     2     |
+  |12 Victoria     |1850, Sept. 13 |Hind       | London    |     3     |
+  |13 Egeria       |1850, Nov. 2   |Gasperis   | Naples    |     3     |
+  |14 Irene        |1851, May 19   |Hind       | London    |     4     |
+  |15 Eunomia      |1851, July 29  |Gasperis   | Naples    |     4     |
+  |16 Psyche       |1852, March 17 |Gasperis   | Naples    |     5     |
+  |17 Thetis       |1852, April 17 |Luther     | Bilk      |     1     |
+  |18 Melpomene    |1852, June 24  |Hind       | London    |     5     |
+  |19 Fortuna      |1852, August 22|Hind       | London    |     6     |
+  |20 Massilia     |1852, Sept. 19 |Gasperis   | Naples    |     6     |
+  |21 Lutetia      |1852, Nov. 15  |Goldschmidt| Paris     |     1     |
+  |22 Calliope     |1852, Nov. 16  |Hind       | London    |     7     |
+  |23 Thalia       |1852, Dec. 15  |Hind       | London    |     8     |
+  |24 Themis       |1853, April 5  |Gasperis   | Naples    |     7     |
+  |25 Phocea       |1853, April 6  |Chacornac  | Marseilles|     1     |
+  |26 Proserpine   |1853, May 5    |Luther     | Bilk      |     2     |
+  |27 Euterpe      |1853, Nov. 8   |Hind       | London    |     9     |
+  |28 Bellona      |1854, March 1  |Luther     | Bilk      |     3     |
+  |29 Amphitrite   |1854, March 1  |Marth      | London    |     1     |
+  |30 Urania       |1854, July 22  |Hind       | London    |    10     |
+  |31 Euphrosyne   |1854, Sept. 1  |Furguson   | Washington|     1     |
+  |32 Pomona       |1854, Oct. 26  |Goldschmidt| Paris     |     2     |
+  |33 Polyhymnia   |1854, Oct. 28  |Chacornac  | Paris     |     2     |
+  |34 Circe        |1855, April 6  |Chacornac  | Paris     |     3     |
+  |35 Leucothea    |1855, April 19 |Luther     | Bilk      |     4     |
+  |36 Atalante     |1855, Oct. 5   |Goldschmidt| Paris     |     3     |
+  |37 Fides        |1855, Oct. 5   |Luther     | Bilk      |     5     |
+  |38 Leda         |1856, Jan. 12  |Chacornac  | Paris     |     4     |
+  |39 Lætitia      |1856, Feb. 8   |Chacornac  | Paris     |     5     |
+  |40 Harmonia     |1856, March 31 |Goldschmidt| Paris     |     4     |
+  |41 Daphne       |1856, May 22   |Goldschmidt| Paris     |     5     |
+  |42 Isis         |1856, May 23   |Pogson     | Oxford    |     1     |
+  |43 Ariadne      |1857, April 15 |Pogson     | Oxford    |     2     |
+  |44 Nysa         |1857, May 27   |Goldschmidt| Paris     |     6     |
+  |45 Eugenia      |1857, June 28  |Goldschmidt| Paris     |     7     |
+  |46 Hastia       |1857, August 16|Pogson     | Oxford    |     3     |
+  |47 Aglaia       |1857, Sept. 15 |Luther     | Bilk      |     6     |
+  |48 Doris        |1857, Sept. 19 |Goldschmidt| Paris     |     8     |
+  |49 Pales        |1857, Sept. 19 |Goldschmidt| Paris     |     9     |
+  |50 Virginia     |1857, Oct. 4   |Furguson   | Washington|     2     |
+  |51 Nemausa      |1858, Jan. 22  |Laurent    | Nismes    |     1     |
+  |52 Europa       |1858, Feb. 6   |Goldschmidt| Paris     |    10     |
+  |53 Calypso      |1858, April 8  |Luther     | Bilk      |     7     |
+  |54 Alexandra    |1858, Sept. 11 |Goldschmidt| Paris     |    11     |
+  |55 (Not named)  |1858, Sept. 11 |Searle     | Albany    |     1     |
+  +----------------+---------------+-----------+-----------+-----------+
+
+
+THE COMET OF DONATI.
+
+While this sheet was passing through the press, the attention of
+astronomers, and of the public generally, was drawn to the fact of
+the above Comet passing (on Oct. 18) within nine millions of miles of
+the planet Venus, or less than 9/100ths of the earth’s distance from
+the Sun. “And (says Mr. Hind, the astronomer), it is obvious that
+if the comet had reached its least distance from the sun a few days
+earlier than it has done, the planet might have passed through it;
+and I am very far from thinking that close proximity to a comet of
+this description would be unattended with danger. The inhabitants of
+Venus will witness a cometary spectacle far superior to that which has
+recently attracted so much attention here, inasmuch as the tail will
+doubtless appear twice as long from that planet as from the earth, and
+the nucleus proportionally more brilliant.”
+
+This Comet was first discovered by Dr. G. B. Donati, astronomer at
+the Museum of Florence, on the evening of the 2d of June, in right
+ascension 141° 18′, and north declination 23° 47′, corresponding to
+a position near the star Leonis. Previous to this date we had no
+knowledge of its existence, and therefore it was not a predicted
+comet; neither is it the one last observed in 1556. At the date of
+discovery it was distant from the earth 228,000,000 of miles, and was
+an excessively faint object in the largest telescopes.
+
+The tail, from October 2 to 16, when the comet was most conspicuous,
+appears to have maintained an average length of at least 40,000,000
+miles, subtending an angle varying from 30° to 40°. The dark line or
+space down the centre, frequently remarked in other great comets,
+was a striking characteristic in that of Donati. The nucleus, though
+small, was intensely brilliant in powerful instruments, and for some
+time bore high magnifiers to much greater advantage than is usual with
+these objects. In several respects this comet resembled the famous
+ones of 1744, 1680, and 1811, particularly as regards the signs of
+violent agitation going on in the vicinity of the nucleus, such as
+the appearance of luminous jets, spiral offshoots, &c., which rapidly
+emanated from the planetary point and as quickly lost themselves in the
+general nebulosity of the head.
+
+On the 5th Oct. the most casual observer had an opportunity of
+satisfying himself as to the accuracy of the mathematical theory of
+the motions of comets in the near approach of the nucleus of Donati’s
+to Arcturus, the principal star in the constellation Bootes. The
+circumstance of the appulse was very nearly as predicted by Mr. Hind.
+
+The comet, according to the investigations by M. Loewy, of the
+Observatory of Vienna, arrived at its least distance from the sun a few
+minutes after eleven o’clock on the morning of the 30th of September;
+its longitude, as seen from the sun at this time, being 36° 13′, and
+its distance from him 55,000,000 miles. The longer diameter of its
+orbit is 184 times that of the earth’s, or 35,100,000,000 miles;
+yet this is considerably less than 1/1000th of the distance of the
+nearest fixed star. As an illustration, let any one take a half-sheet
+of note-paper, and marking a circle with a sixpence in one corner
+of it, describe therein our solar system, drawing the orbits of the
+earth and the inferior planets as small as he can by the aid of a
+magnifying-glass. If the circumference of the sixpence stands for the
+orbit of Neptune, then an oval filling the page will fairly represent
+the orbit of Donati’s comet; and if the paper be laid upon the pavement
+under the west door of St. Paul’s Cathedral, London, the length of that
+edifice will inadequately represent the distance of the nearest fixed
+star. The time of revolution resulting from Mr. Loewy’s calculations
+is 2495 years, which is about 500 years less than that of the comet of
+1811 during the period it was visible from the earth.
+
+That the comet should take more than 2000 years to travel round the
+above page of note-paper is explained by its great diminution of speed
+as it recedes from the sun. At its perihelion it travelled at the rate
+of 127,000 miles an hour, or more than twice as fast as the earth,
+whose motion is about 1000 miles a minute. At its aphelion, however,
+or its greatest distance from the sun, the comet is a very slow body,
+sailing at the rate of 480 miles an hour, or only eight times the
+speed of a railway express. At this pace, were it to travel onward in
+a straight line, the lapse of a million of years would find it still
+travelling half way between our sun and the nearest fixed star.
+
+As this comet last visited us between 2000 and 2495 years since, we
+know that its appearance was at an interesting period of the world’s
+history. It might have terrified the Athenians into accepting the
+bloody code of Draco. It might have announced the destruction of
+Nineveh, or of Babylon, or the capture of Jerusalem by Nebuchadnezzar.
+It might have been seen by the expedition which sailed round Africa
+in the reign of Pharaoh Necho. It might have given interest to the
+foundation of the Pythian games. Within the probable range of its
+last visitation are comprehended the whole of the great events of the
+history of Greece; and among the spectators of the comet may have been
+the so-called sages of Greece and even the prophets of Holy Writ:
+Thales might have attempted to calculate its return, and Jeremiah might
+have tried to read its warning.--_Abridged from a Communication from
+Mr. Hind to the Times, and from a Leader in that Journal._
+
+
+
+
+FOOTNOTES:
+
+
+[1] From a photograph, with figures, to show the relative size of the
+tube aperture.
+
+[2] Weld’s _History of the Royal Society_, vol. ii. p. 188.
+
+[3] Dr. Whewell (_Bridgewater Treatise_, p. 266) well observes, that
+Boyle and Pascal are to hydrostatics what Galileo is to mechanics, and
+Copernicus, Kepler, and Newton are to astronomy.
+
+[4] The Rev. Mr. Turnor recollects that Mr. Jones, the tutor,
+mentioned, in one of his lectures on optics, that the reflecting
+telescope belonging to Newton was then lodged in the observatory over
+the gateway; and Mr. Turnor thinks that he once saw it, with a finder
+affixed to it.
+
+[5] The story of the dog “Diamond” having caused the burning of
+certain papers is laid in London, and in Newton’s later years. In the
+notes to Maude’s _Wenleysdale_, a person then living (1780) relates,
+that Sir Isaac being called out of his study to a contiguous room, a
+little dog, called Diamond, the constant but incurious attendant of
+his master’s researches, happened to be left among the papers, and
+by a fatality not to be retrieved, as it was in the latter part of
+Sir Isaac’s days, threw down a lighted candle, which consumed the
+almost finished labour of some years. Sir Isaac returning too late
+but to behold the dreadful wreck, rebuked the author of it with an
+exclamation (_ad sidera palmas_), “O Diamond! Diamond! thou little
+knowest the mischief done!” without adding a single stripe. M. Biot
+gives this fiction as a true story, which happened some years after
+the publication of the _Principia_; and he characterises the accident
+as having deprived the sciences forever of the fruit of so much of
+Newton’s labours.--Brewster’s _Life_, vol. ii. p. 139, note. Dr. Newton
+remarks, that Sir Isaac never had any communion with dogs or cats; and
+Sir David Brewster adds, that the view which M. Biot has taken of the
+idle story of the dog Diamond, charged with fire-raising among Newton’s
+manuscripts, and of the influence of this accident upon the mind of
+their author, is utterly incomprehensible. The fiction, however, was
+turned to account in giving colour to M. Biot’s misrepresentation.
+
+[6] Bohn’s edition.
+
+[7] When at Pisa, many years since, Captain Basil Hall investigated
+the origin and divergence of the tower from the perpendicular, and
+established completely to his own satisfaction that it had been built
+from top to bottom originally just as it now stands. His reasons for
+thinking so were, that the line of the tower, on that side towards
+which it leans, has not the same curvature as the line on the opposite,
+or what may be called the upper side. If the tower had been built
+upright, and then been made to incline over, the line of the wall on
+that side towards which the inclination was given would be more or less
+concave in that direction, owing to the nodding or “swagging over” of
+the top, by the simple action of gravity acting on a very tall mass
+of masonry, which is more or less elastic when placed in a sloping
+position. But the contrary is the fact; for the line of wall on the
+side towards which the tower leans is decidedly more convex than the
+opposite side. Captain Hall had therefore no doubt whatever that the
+architect, in rearing his successive courses of stones, gained or
+stole a little at each layer, so as to render his work less and less
+overhanging as he went up; and thus, without betraying what he was
+about, really gained stability.--See _Patchwork_.
+
+[8] Lord Bacon proposed that, in order to determine whether the gravity
+of the earth arises from the gravity of its parts, a clock-pendulum
+should be swung in a mine, as was recently done at Harton colliery by
+the Astronomer-Royal.
+
+When, in 1812, Ampère noted the phenomena of the pendulum, and showed
+that its movement was produced only when the eye of the observer was
+fixed on the instrument, and endeavoured to prove thereby that the
+motion was due to a play of the muscles, some members of the French
+Academy objected to the consideration of a subject connected to such an
+extent with superstition.
+
+[9] This curious fact was first recorded by Pepys, in his _Diary_,
+under the date 31st of July 1665.
+
+[10] The result of these experiments for ascertaining the variation
+of the gravity at great depths, has proved beyond doubt that the
+attraction of gravitation is increased at the depth of 1250 feet by
+1/19000 part.
+
+[11] See the account of Mr. Baily’s researches (with two illustrations)
+in _Things not generally Known_, p. vii., and “Weight of the Earth,” p.
+16.
+
+[12] Fizeau gives his result in leagues, reckoning twenty-five to the
+equatorial degree. He estimates the velocity of light at 70,000 such
+leagues, or about 210,000 miles in the second.
+
+[13] See _Things not generally Known_, p. 88.
+
+[14] Some time before the first announcement of the discovery of
+sun-painting, the following extract from Sir John Herschel’s _Treatise
+on Light_, in the _Encyclopædia Metropolitana_, appeared in a popular
+work entitled _Parlour Magic_: “Strain a piece of paper or linen upon
+a wooden frame, and sponge it over with a solution of nitrate of
+silver in water; place it behind a painting upon glass, or a stained
+window-pane, and the light, traversing the painting or figures, will
+produce a copy of it upon the prepared paper or linen; those parts in
+which the rays were least intercepted being the shadows of the picture.”
+
+[15] In his book on Colours, Mr. Doyle informs us that divers, if not
+all, essential oils, as also spirits of wine, when shaken, “have a
+good store of bubbles, which appear adorned with various and lively
+colours.” He mentions also that bubbles of soap and turpentine exhibit
+the same colours, which “vary according to the incidence of the sight
+and the position of the eye;” and he had seen a glass-blower blow
+bubbles of glass which burst, and displayed “the varying colours of the
+rainbow, which were exceedingly vivid.”
+
+[16] The original idea is even attributed to Copernicus. M. Blundevile,
+in his _Treatise on Cosmography_, 1594, has the following passage,
+perhaps the most distinct recognition of authority in our language:
+“How prooue (prove) you that there is but one world? By the authoritie
+of Aristotle, who saieth that if there were any other world out of
+this, then the earth of that world would mooue (move) towards the
+centre of this world,” &c.
+
+Sir Isaac Newton, in a conversation with Conduitt, said he took “all
+the planets to be composed of the same matter with the earth, viz.
+earth, water, and stone, but variously concocted.”
+
+[17] Sir William Herschel ascertained that our solar system is
+advancing towards the constellation Hercules, or more accurately to a
+point in space whose right ascension is 245° 52′ 30″, and north polar
+distance 40° 22′; and that the quantity of this motion is such, that to
+an astronomer placed in Sirius, our sun would appear to describe an arc
+of little more than _a second_ every year.--_North-British Review_, No.
+3.
+
+[18] See M. Arago’s researches upon this interesting subject, in
+_Things not generally Known_, p. 4.
+
+[19] This eloquent advocacy of the doctrine of “More Worlds than One”
+(referred to at p. 51) is from the author’s valuable _Outlines of
+Astronomy_.
+
+[20] Professor Challis, of the Cambridge Observatory, directing the
+Northumberland telescope of that institution to the place assigned by
+Mr. Adams’s calculations and its vicinity on the 4th and 12th of August
+1846, saw the planet on both those days, and noted its place (among
+those of other stars) for re-observation. He, however, postponed the
+_comparison_ of the places observed, and not possessing Dr. Bremiker’s
+chart (which would at once have indicated the presence of an unmapped
+star), remained in ignorance of the planet’s existence as a visible
+object till the announcement of such by Dr. Galle.
+
+[21] For several interesting details of Comets, see “Destruction of the
+World by a Comet,” in _Popular Errors Explained and Illustrated_, new
+edit. pp. 165-168.
+
+[22] The letters of Sir Isaac Newton to Dr. Bentley, containing
+suggestions for the Boyle Lectures, possess a peculiar interest in the
+present day. “They show” (says Sir David Brewster) “that the _nebular
+hypothesis_, the dull and dangerous heresy of the age, is incompatible
+with the established laws of the material universe, and that an
+omnipotent arm was required to give the planets their positions and
+motions in space, and a presiding intelligence to assign to them the
+different functions they had to perform.”--_Life of Newton_, vol. ii.
+
+[23] The constitution of the nebulæ in the constellation of Orion has
+been resolved by this instrument; and by its aid the stars of which it
+is composed burst upon the sight of man for the first time.
+
+[24] Several specimens of Meteoric Iron are to be seen in the
+Mineralogical Collection in the British Museum.
+
+[25] _Life of Sir Isaac Newton_, vol. i. p. 62.
+
+[26] _Description of the Monster Telescope_, by Thomas Woods, M.D. 4th
+edit. 1851.
+
+[27] This instrument also discovered a multitude of new objects in the
+moon; as a mountainous tract near Ptolemy, every ridge of which is
+dotted with extremely minute craters, and two black parallel stripes in
+the bottom of Aristarchus. Dr. Robinson, in his address to the British
+Association in 1843, stated that in this telescope a building the size
+of the Court-house at Cork would be easily visible on the lunar surface.
+
+[28] Mr. Hopkins supports his Glacial Theory by regarding the _Waves
+of Translation_, investigated by Mr. Scott Russell, as furnishing
+a sufficient moving power for the transportation of large rounded
+boulders, and the formation of drifted gravel. When these waves of
+translation are produced by the sudden elevation of the surface of
+the sea, the whole mass of water from the surface to the bottom of
+the ocean moves onward, and becomes a mechanical agent of enormous
+power. Following up this view, Mr. Hopkins has shown that “elevations
+of continental masses of only 50 feet each, and from beneath an ocean
+having a depth of between 300 and 400 feet, would cause the most
+powerful divergent waves, which could transport large boulders to great
+distances.”
+
+[29] It is scarcely too much to say, that from the collection of
+specimens of building-stones made upon this occasion, and first
+deposited in a house in Craig’s Court, Charing Cross, originated,
+upon the suggestion of Sir Henry Delabeche, the magnificent Museum of
+Practical Geology in Jermyn Street; one of the most eminently practical
+institutions of this scientific age.
+
+[30] Mr. R. Mallet, F.R.S., and his son Dr. Mallet, have constructed a
+seismographic map of the world, with seismic bands in their position
+and relative intensity; and small black discs to denote volcanoes,
+femaroles, and soltataras, and shades indicating the areas of
+subsidence.
+
+[31] It has been computed that the shock of this earthquake pervaded
+an area of 700,000 miles, or the twelfth part of the circumference of
+the globe. This dreadful shock lasted only five minutes; and nearly
+the whole of the population being within the churches (on the feast of
+All Saints), no less than 30,000 persons perished by the fall of these
+edifices.--See _Daubeny on Volcanoes_; _Translator’s note, Humboldt’s
+Cosmos_.
+
+[32] Mr. Murray mentions, on the authority of the Rev. Dr. Robinson,
+of the Observatory at Armagh, that a rough diamond with a red tint,
+and valued by Mr. Rundell at twenty guineas, was found in Ireland,
+many years since, in the bed of a brook flowing through the county of
+Fermanagh.
+
+[33] The use of malachite in ornamental work is very extensive in
+Russia. Thus, to the Great Exhibition of 1851 were sent a pair of
+folding-doors veneered with malachite, 13 feet high, valued at
+6000_l._; malachite cases and pedestals from 1500_l._ to 3000_l._
+a-piece, malachite tables 400_l._, and chairs 150_l._ each.
+
+[34] Longfellow has written some pleasing lines on “The Fiftieth
+Birthday of M. Agassiz. May 28, 1857,” appended to “The Courtship of
+Miles Standish,” 1858.
+
+[35] The _sloth_ only deserves its name when it is obliged to attempt
+to proceed along the ground; when it has any thing which it can lay
+hold of it is agile enough.
+
+[36] Dr. A. Thomson has communicated to _Jameson’s Journal_, No. 112,
+a Description of the Caves in the North Island, with some general
+observations on this genus of birds. He concludes them to have been
+indolent, dull, and stupid; to have lived chiefly on vegetable food in
+mountain fastnesses and secluded caverns.
+
+In the picture-gallery at Drayton Manor, the seat of Sir Robert Peel,
+hangs a portrait of Professor Owen, and in his hand is depicted the
+tibia of a Moa.
+
+[37] According to the law of correlation, so much insisted on by
+Cuvier, a superior character implies the existence of its inferiors,
+and that too in definite proportions and constant connections; so
+that we need only the assurance of one character, to be able to
+reconstruct the whole animal. The triumph of this system is seen in
+the reconstruction of extinct animals, as in the above case of the
+Dinornis, accomplished by Professor Owen.
+
+[38] Not only at London, but at Paris, Vienna, Berlin, Turin. St.
+Petersburg, and almost every other capital in Europe; at Liege, Caen,
+Montpellier, Toulouse, and several other large towns,--wherever,
+in fact, there are not great local obstacles,--the tendency of the
+wealthier inhabitants to group themselves to the west is as strongly
+marked as in the British metropolis. At Pompeii, and other ancient
+towns, the same thing maybe noticed; and where the local configuration
+of the town necessitates an increase in a different direction, the
+moment the obstacle ceases houses spread towards the west.
+
+[39] By far the most complete set of experiments on the Radiation
+of Heat from the Earth’s Surface at Night which have been published
+since Dr. Wells’s Memoir _On Dew_, are those of Mr. Glaisher, F.R.S.,
+_Philos. Trans._ for 1847.
+
+[40] The author is largely indebted for the illustrations in this new
+field of research to Lieutenant Maury’s valuable work, _The Physical
+Geography of the Sea_. Sixth edition. Harper, New York; Low, Son, and
+Co., London.
+
+[41] It is the chloride of magnesia which gives that damp sticky
+feeling to the clothes of sailors that are washed or wetted with salt
+water.
+
+[42] This fraction rests on the assumption that the dilatation of the
+substances of which the earth is composed is equal to that of glass,
+that is to say, 1/18000 for 1°. Regarding this hypothesis, see Arago,
+in the _Annuaire_ for 1834, pp. 177-190.
+
+[43] Electricity, traversing excessively rarefied air or vapours,
+gives out light, and doubtless also heat. May not a continual current
+of electric matter be constantly circulating in the sun’s immediate
+neighbourhood, or traversing the planetary spaces, and exerting in the
+upper regions of its atmosphere those phenomena of which, on however
+diminutive a scale, we have yet an unequivocal manifestation in our
+Aurora Borealis?
+
+[44] Could we by mechanical pressure force water into a solid state, an
+immense quantity of heat would be set free.
+
+[45] See Mr. Hunt’s popular work, _The Poetry of Science; or, Studies
+of Physical Phenomena of Nature_. Third edition, revised and enlarged.
+Bohn, 1854.
+
+[46] Canton was the first who in England verified Dr. Franklin’s idea
+of the similarity of lightning and the electric fluid, July 1752.
+
+[47] This is mentioned in _Procli Diadochi Paraphrasis Ptolem._, 1635.
+(Delambre, _Hist. de l’Astronomie ancienne_.)
+
+[48] The first Variation-Compass was constructed, before 1525, by an
+ingenious apothecary of Seville, Felisse Guillen. So earnest were
+the endeavours to learn more exactly the direction of the curves of
+magnetic declination, that in 1585 Juan Jayme sailed with Francisco
+Gali from Manilla to Acapulco, for the sole purpose of trying in the
+Pacific a declination instrument which he had invented.--_Humboldt._
+
+[49] Gilbert was surgeon to Queen Elizabeth and James I., and died
+in 1603. Whewell justly assigns him an important place among the
+“practical reformers of the physical sciences.” He adopted the
+Copernican doctrine, which Lord Bacon’s inferior aptitude for physical
+research led him to reject.
+
+[50] This illustration, it will be seen, does not literally correspond
+with the details which precede it.
+
+[51] Mr. Crosse gave to the meeting a general invitation to Fyne Court;
+one of the first to accept which was Sir Richard Phillips, who, on
+his return to Brighton, described in a very attractive manner, at the
+Sussex Institution, Mr. Crosse’s experiments and apparatus; a report of
+which being communicated to the _Brighton Herald_, was quoted in the
+_Literary Gazette_, and thence copied generally into the newspapers of
+the day.
+
+[52] These experiments were performed at the expense of the Royal
+Society, and cost 10_l._ 5_s._ 6_d._ In the Paper detailing the
+experiments, printed in the 45th volume of the _Philosophical
+Transactions_, occurs the first mention of Dr. Franklin’s name, and of
+his theory of positive and negative electricity.--_Weld’s Hist. Royal
+Soc._ vol. i. p. 467.
+
+[53] In this year Andrew Crosse said: “I prophesy that by means of
+the electric agency we shall be enabled to communicate our thoughts
+instantaneously with the uttermost parts of the earth.”
+
+[54] To which paper the writer is indebted for many of these details.
+
+[55] These illustrations have been in the main selected and abridged
+from papers in the _Companion to the Almanac_, 1858, and the _Penny
+Cyclopædia_, 2d supp.
+
+[56] Newton was, however, much pestered with inquirers; and a
+Correspondent of the _Gentleman’s Magazine_, in 1784, relates that he
+once had a transient view of a Ms. in Pope’s handwriting, in which
+he read a verified anecdote relating to the above period. Sir Isaac
+being often interrupted by ignorant pretenders to the discovery of
+the longitude, ordered his porter to inquire of every stranger who
+desired admission whether he came about the longitude, and to exclude
+such as answered in the affirmative. Two lines in Pope’s Ms., as the
+Correspondent recollects, ran thus:
+
+    “‘Is it about the longitude you come?’
+    The porter asks: ‘Sir Isaac’s not at home.’”
+
+[57] In trying the merits of Harrison’s chronometers, Dr. Maskelyne
+acquired that knowledge of the wants of nautical astronomy which
+afterwards led to the formation of the Nautical Almanac.
+
+[58] A slight electric shock is given to a man at a certain portion of
+the skin; and he is directed the moment he feels the stroke to make a
+certain motion, as quickly as he possibly can, with the hands or with
+the teeth, by which the time-measuring current is interrupted.
+
+[59] Through the calculations of M. Le Verrier.
+
+
+
+
+GENERAL INDEX
+
+
+  Abodes of the Blest, 58.
+
+  Acarus of Crosse and Weeks, 218.
+
+  Accuracy of Chinese Observers, 159.
+
+  Adamant, What was it?, 123.
+
+  Aeronautic Voyage, Remarkable, 169.
+
+  Agassiz, Discoveries of, 127.
+
+  Air, Weight of, 14.
+
+  All the World in Motion, 11.
+
+  Alluvial Land of Egypt, 110.
+
+  Ancient World, Science of the, 1.
+
+  Animals in Geological Times, 128.
+
+  Anticipations of the Electric Telegraph, 220-224.
+
+  Arago on Protection from Storms, 159.
+
+  Arctic Climate, Phenomena of, 162.
+
+  Arctic Explorations, Rae’s, 162.
+
+  Arctic Regions, Scenery and Life of, 180.
+
+  Arctic Temperature, 161.
+
+  Armagh Observatory Level, Change of, 144.
+
+  Artesian Fire-Springs, 118.
+
+  Artesian Well of Grenelle, 114.
+
+  Astronomer, Peasant, 101.
+
+  Astronomer’s Dream verified, 88.
+
+  Astronomers, Triad of Contemporary, 100.
+
+  Astronomical Observations, Nicety of, 102.
+
+  Astronomy and Dates on Monuments, 55.
+
+  Astronomy and Geology, Identity of, 104.
+
+  Astronomy, Great Truths of, 54.
+
+  Atheism, Folly of, 3.
+
+  Atlantic, Basin of the, 171.
+
+  Atlantic, Gales of the, 171.
+
+  Atlantic Telegraph, the, 226-228.
+
+  Atmosphere, Colours of the, 147.
+
+  Atmosphere compared to a Steam-engine, 152.
+
+  Atmosphere, Height of, 147.
+
+  Atmosphere, the, 146.
+
+  Atmosphere, the purest, 150.
+
+  Atmosphere, Universality of the, 147.
+
+  Atmosphere weighed by Pascal, 148.
+
+  Atoms of Elementary Bodies, 13.
+
+  Atoms, the World of, 13.
+
+  Aurora Borealis, Halley’s hypothesis of, 198.
+
+  Aurora Borealis, Splendour of the, 165.
+
+  Australian Cavern, Inmates of, 137.
+
+  Australian Pouch-Lion, 137.
+
+  Axis of Rotation, the, 11.
+
+
+  Barometer, Gigantic, 151.
+
+  Barometric Measurement, 151.
+
+  Batteries, Minute and Vast, 204.
+
+  Birds, Gigantic, of New Zealand, Extinct, 139.
+
+  “Black Waters, the,” 182.
+
+  Bodies, Bright, the Smallest, 31.
+
+  Bodies, Compression of, 12.
+
+  Bodies, Fall of, 16.
+
+  Bottles and Currents at Sea, 172.
+
+  Boulders, How transported to Great Heights, 105.
+
+  Boyle on Colours, 49.
+
+  Boyle, Researches of, 6.
+
+  Brain, Impressions transmitted to, 235.
+
+  Buckland, Dr., his Geological Labours, 127.
+
+  Building-Stone, Wear of, 108.
+
+  Burnet’s Theory of the Earth, 125.
+
+  Bust, Magic, 36.
+
+
+  Candle-flame, Nature of, 237.
+
+  Canton’s Artificial Magnets, 196.
+
+  Carnivora of Britain, Extinct, 132.
+
+  Carnivores, Monster, of France, 138.
+
+  Cataract, Great, in India, 183.
+
+  Cat, Can it see in the Dark?, 51.
+
+  Caves of New Zealand and its Gigantic Birds, 140.
+
+  Cave Tiger or Lion of Britain, 133.
+
+  Central Heat, Theory of, 116.
+
+  Chabert, “the Fire King,” 192.
+
+  Chalk Formation, the, 108.
+
+  Changes on the Earth’s Surface, 142.
+
+  Chantrey, Heat-Experiments by, 192.
+
+  Children’s powerful Battery, 204.
+
+  Chinese, the, and the Magnetic Needle, 194.
+
+  Chronometers, Marine, How rated at Greenwich Observatory, 229.
+
+  Climate, finest in the World, 149.
+
+  Climate, Variations of, 148.
+
+  Climates, Average, 149.
+
+  Clock, How to make Electric, 212.
+
+  Cloud-ring, the Equatorial, 156.
+
+  Clouds, Fertilisation of, 151.
+
+  Coal, Torbane-Hill, 123.
+
+  Coal, What is it?, 123.
+
+  Cold in Hudson’s Bay, 160.
+
+  Colour of a Body, and its Magnetic Properties, 197.
+
+  Colours and Tints, Chevreul on, 37.
+
+  Colours most frequently hit in Battle, 36.
+
+  Comet, the, of Donati, 240, 241.
+
+  Comet, Great, of 1843, 84.
+
+  Comets, Magnitude of, 84.
+
+  Comets visible in Sunshine, 84.
+
+  Computation, Power of, 10.
+
+  Coney of Scripture, 137.
+
+  Conic Sections, 10.
+
+  Continent Outlines not fixed, 145.
+
+  Corpse, How soon it decays, 237.
+
+  “Cosmos, Science of the,” 10.
+
+  Crosse, Andrew, his Artificial Crystals and Minerals, 216-219.
+
+  Crosse Mite, the, 218.
+
+  Crystallisation, Reproductive, 26.
+
+  Crystallisation, Theory of, 24.
+
+  Crystallisation, Visible, 25.
+
+  Crystals, Immense, 24.
+
+  “Crystal Vault of Heaven,” 55.
+
+
+  Davy, Sir Humphry, obtains Heat from Ice, 190.
+
+  Davy’s great Battery at the Royal Institution, 204.
+
+  Day, Length of, and Heat of the Earth, 186.
+
+  Day’s Length at the Poles, 65.
+
+  Declination of the Needle, 197.
+
+  Descartes’ Labours in Physics, 9.
+
+  Desert, Intense Heat and Cold of the, 163.
+
+  Dew-drop, Beauty of the, 157.
+
+  Dew-fall in one year, 157.
+
+  Dew graduated to supply Vegetation, 157.
+
+  Diamond, Geological Age of, 122.
+
+  Diamond Lenses for Microscopes, 40.
+
+  “Diamond,” Newton’s Dog, 8.
+
+  Dinornis elephantopus, the, 139, 140.
+
+  Dinotherium, or Terrible Beast, the, 136.
+
+  Diorama, Illusion of the, 37.
+
+
+  Earth and Man compared, 22.
+
+  Earth, Figure of the, 21.
+
+  Earth, Mass and Density of, 21.
+
+  Earth’s Annual Motion, 12.
+
+  Earth’s Magnitude, to ascertain, 21.
+
+  Earth’s Surface, Mean Temperature of, 23.
+
+  Earth’s Temperature, Interior, 116.
+
+  Earth’s Temperature Stationary, 23.
+
+  Earth, the, a Magnet, 197.
+
+  Earthquake, the Great Lisbon, 121.
+
+  Earthquakes and the Moon, 121.
+
+  Earthquakes, Rumblings of, 120.
+
+  Earthquake-Shock, How to measure, 120.
+
+  Earth-Waves, 119.
+
+  Eclipses, Cause of, 74.
+
+  Egypt, Alluvial Land of, 110.
+
+  Electric Girdle for the Earth, 224.
+
+  Electric Incandescence of Charcoal Points, 204.
+
+  Electric Knowledge, Germs of, 207.
+
+  Electric Light, Velocity of, 209.
+
+  Electric Messages, Time lost in, 225.
+
+  Electric Paper, 209.
+
+  Electric Spark, Duration of, 209.
+
+  Electric Telegraph, Anticipations of the, 220-224.
+
+  Electric Telegraph, Consumption of, 224.
+
+  Electric Telegraph in Astronomy and Longitude, 225.
+
+  Electric Telegraph and Lightning, 226.
+
+  Electric and Magnetic Attraction, Identity of, 210.
+
+  Electrical Kite, Franklin’s, 213.
+
+  Electricity and Temperature, 208.
+
+  Electricity in Brewing, 209.
+
+  Electricity, Vast Arrangement of, 208.
+
+  Electricity, Water decomposed by, 208.
+
+  Electricities, the Two, 214.
+
+  Electro-magnetic Clock, Wheatstone’s, 211.
+
+  Electro-magnetic Engine, Theory of, 210.
+
+  Electro-magnets, Horse-shoe, 199.
+
+  Electro-telegraphic Message to the Stars, 226.
+
+  Elephant and Tortoise of India, 135.
+
+  End of our System, 92.
+
+  England in the Eocene Period, 129.
+
+  English Channel, Probable Origin of, 105.
+
+  Eocene Period, the, 129.
+
+  Equatorial Cloud-ring, 156.
+
+  “Equatorial Doldrums,” 156.
+
+  Error upon Error, 185.
+
+  Exhilaration in ascending Mountains, 163.
+
+  Eye and Brain seen through a Microscope, 41.
+
+  Eye, interior, Exploration of, 236.
+
+
+  Fall of Bodies, Rate of, 16.
+
+  Falls, Height of, 16.
+
+  Faraday, Genius and Character of, 193.
+
+  Faraday’s Electrical Illustrations, 214.
+
+  “Father of English Geology, the,” 126.
+
+  Fertilisation of Clouds, 151.
+
+  Fire, Perpetual, 117.
+
+  Fire-balls and Shooting Stars, 89.
+
+  Fire-Springs, Artesian, 118.
+
+  Fishes, the most Ancient, 132.
+
+  Flying Dragon, the, 130.
+
+  Force neither created nor destroyed, 18.
+
+  Force of Running Water, 114.
+
+  Fossil Human Bones, 131.
+
+  Fossil Meteoric Stones, none, 92.
+
+  Fossil Rose, none, 142.
+
+  Foucault’s Pendulum Experiments, 22.
+
+  Franklin’s Electrical Kite, 213.
+
+  Freezing Cavern in Russia, 115.
+
+  Fresh Water in Mid-Ocean, 182.
+
+
+  Galilean Telescope, the, 93.
+
+  Galileo, What he first saw with the Telescope, 93.
+
+  Galvani and Volta, 205.
+
+  Galvanic Effects, Familiar, 203.
+
+  Galvanic Waves on the same Wire, Non-interference of, 225.
+
+  “Gauging the Heavens,” 58.
+
+  Genius, Relics of, 5.
+
+  Geology and Astronomy, Identity of, 104.
+
+  Geology of England, 105.
+
+  Geological Time, 143.
+
+  George III., His patronage of Herschel, 95.
+
+  Gilbert on Magnetic and Electric forces, 201.
+
+  Glacial Theory, by Hopkins, 105.
+
+  Glaciers, Antiquity of, 109.
+
+  Glaciers, Phenomena of, Illustrated, 108.
+
+  Glass, Benefits of, to Man, 92.
+
+  Glass broken by Sand, 26.
+
+  Glyptodon, the, 137.
+
+  Gold, Lumps of, in Siberia, 124.
+
+  Greenwich Observatory, Chronometers rated at, 229-232.
+
+  Grotto del Cane, the, 112.
+
+  Gulf-Stream and the Temperature of London, 115.
+
+  Gunpowder-Magazines, Danger to, 216.
+
+  Gymnotus and the Voltaic Battery, 206.
+
+  Gyroscope, Foucault’s, 22.
+
+
+  Hail and Storms, Protection against, 159.
+
+  Hail-storm, Terrific, 160.
+
+  Hair, Microscopical Examination of, 41.
+
+  Harrison’s Prize Chronometers, 229-232.
+
+  Heat and Evaporation, 188.
+
+  Heat and Mechanical Power, 188.
+
+  Heat by Friction, 189.
+
+  Heat, Distinctions of, 187.
+
+  Heat, Expenditure of, by the Sun, 186.
+
+  Heat from Gas-lighting, 189.
+
+  Heat from Wood and Ice, 190.
+
+  Heat, Intense, Protection from, 191, 192.
+
+  Heat, Latent, 187.
+
+  Heat of Mines, 188.
+
+  Heat, Nice Measurement of, 186.
+
+  Heat, Origin of, in our System, 87.
+
+  Heat passing through Glass, 189.
+
+  Heat, Repulsion by, 191.
+
+  Heated Metals, Vibration of, 188.
+
+  Heavy Persons, Lifting, 17.
+
+  Heights and Distances, to Calculate, 19.
+
+  Herschel’s Telescopes at Slough, 95.
+
+  Highton’s Minute Battery, 204.
+
+  Hippopotamus of Britain, 135.
+
+  “Horse Latitudes, the,” 173.
+
+  Horse, Three-hoofed, 138.
+
+  Hour-glass, Sand in the, 20.
+
+
+  Ice, Heat from, 190.
+
+  Ice, Warming with, 190.
+
+  Icebergs of the Polar Seas, 180.
+
+  Iguanodon, Food of the, 129.
+
+  Improvement, Perpetuity of, 5.
+
+  Inertia Illustrated, 14.
+
+
+  Jerusalem, Temple of, How protected from Lightning, 167.
+
+  Jew’s Harp, Theory of the, 29.
+
+  Jupiter’s Satellites, Discovery of, 80.
+
+
+  Kaleidoscope, Sir David Brewster’s, 43.
+
+  Kaleidoscope, the, thought to be anticipated, 43.
+
+  Kircher’s “Magnetism,” 194.
+
+
+  Leaning Tower, Stability of, 15.
+
+  Level, Curious Change of, 144.
+
+  Leyden Jar, Origin of the, 216.
+
+  Lifting Heavy Persons, 17.
+
+  Light, Action of, on Muscular Fibres, 34.
+
+  Light, Apparatus for Measuring, 32.
+
+  Light from Buttons, 36.
+
+  Light, Effect of, on the Magnet, 198.
+
+  Light from Fungus, 36.
+
+  Light from the Juice of a Plant, 35.
+
+  Light, Importance of, 34.
+
+  Light, Minuteness of, 34.
+
+  Light Nights, 35.
+
+  Light, Polarisation of, 33.
+
+  Light, Solar and Artificial Compared, 29.
+
+  Light, Source of, 29.
+
+  Light, Undulatory Scale of, 30.
+
+  Light, Velocity of, 31.
+
+  Light, Velocity of, Measured by Fizeau, 32.
+
+  Light from Quartz, 51.
+
+  Lightning-Conductor, Ancient, 167.
+
+  Lightning-Conductors, Service of, 166.
+
+  Lightning Experiment, Fatal, 214.
+
+  Lightning, Photographic Effects of, 45.
+
+  Lightning produced by Rain, 166.
+
+  Lightning, Sheet, What is it?, 165.
+
+  Lightning, Varieties of, 165.
+
+  Lightning, Various Effects of, 168.
+
+  Log, Invention of the, 173.
+
+  London Monument used as an Observatory, 103.
+
+
+  “Maestricht Saurian Fossil,” the, 141.
+
+  Magnet, Power of a, 195.
+
+  Magnets, Artificial, How made, 195.
+
+  Magnetic Clock and Watch, 211.
+
+  Magnetic Electricity discovered, 199.
+
+  Magnetic Hypotheses, 193.
+
+  Magnetic Needle and the Chinese, 194.
+
+  Magnetic Poles, North and South, 201.
+
+  Magnetic Storms, 202.
+
+  “Magnetism,” Kircher’s, 194.
+
+  Malachite, How formed, 124.
+
+  Mammalia in Secondary Rocks, 130.
+
+  Mammoth of the British Isles, 133.
+
+  Mammoth, Remains of the, 134.
+
+  Mars, the Planet, Is it inhabited?, 82.
+
+  Mastodon coexistent with Man, 135.
+
+  Matter, Divisibility of, 14.
+
+  Maury’s Physical Geography of the Sea, 170.
+
+  Mediterranean, Depth of, 176.
+
+  Megatherium, Habits of the, 135.
+
+  Mercury, the Planet, Temperature of, 82.
+
+  Mer de Glace, Flow of the, 110.
+
+  Meteoric Stones, no Fossil, 92.
+
+  Meteorites, Immense, 91.
+
+  Meteorites from the Moon, 89.
+
+  Meteors, Vast Shower of, 91.
+
+  Microscope, the Eye, Brain, and Hair seen by, 41.
+
+  Microscope, Fish-eye, How to make, 40.
+
+  Microscope, Invention of the, 39.
+
+  Microscope for Mineralogists, 42.
+
+  Microscope and the Sea, 42.
+
+  Microscopes, Diamond Lenses for, 40.
+
+  Microscopes, Leuwenhoeck’s, 40.
+
+  Microscopic Writing, 42.
+
+  Milky Way, the, Unfathomable, 85.
+
+  Mineralogy and Geometry, Union of, 25.
+
+  Mirror, Magic, How to make, 43.
+
+  Moon’s Attraction, the, 73.
+
+  Moon, Has it an Atmosphere?, 69.
+
+  Moon, Life in the, 71.
+
+  Moon, Light of the, 70.
+
+  Moon, Mountains in, 72.
+
+  Moon, Measuring the Earth by, 74.
+
+  Moon seen through the Rosse Telescope, 72.
+
+  Moon, Scenery of, 71.
+
+  Moon and Weather, the, 73.
+
+  Moonlight, Heat of, 70.
+
+  “More Worlds than One,” 56, 57.
+
+  Mountain-chains, Elevation of, 107.
+
+  Music of the Spheres, 55.
+
+  Musket-balls found in Ivory, 237.
+
+
+  Natural and Supernatural, the, 6.
+
+  Nautical Almanac, Errors in, 185.
+
+  Nebulæ, Distances of, 85.
+
+  Nebular Hypothesis, the, 86.
+
+  Neptune, the Planet, Discovery of, 83.
+
+  Newton, Sir Isaac, his “Apple-tree,” 8.
+
+  Newton upon Burnet’s Theory of the Earth, 125.
+
+  Newton’s Dog “Diamond,” 8.
+
+  Newton’s first Reflecting Telescope, 94.
+
+  Newton’s “Principia,” 9.
+
+  Newton’s Rooms at Cambridge, 7.
+
+  Newton’s Scale of Colours, 49.
+
+  Newton’s Soap-bubble Experiments, 49, 50.
+
+  New Zealand, Extinct Birds of, 139.
+
+  Niagara, the Roar of, 28.
+
+  Nineveh, Rock-crystal Lens found at, 39.
+
+  Non-conducting Bodies, 215.
+
+  Nothing Lost in the Material World, 18.
+
+
+  Objects really of no Colour, 37.
+
+  Objects, Visibility of, 30.
+
+  Observation, the Art of, 3.
+
+  Observatory, Lacaille’s, 101.
+
+  Observatory, the London Monument, 103.
+
+  Observatory, Shirburn Castle, 101.
+
+  Ocean and Air, Depths of unknown, 174.
+
+  Ocean Highways, 184.
+
+  Ocean, Stability of the, 12.
+
+  Ocean, Transparency of the, 171.
+
+  “Oldest piece of Wood upon the Earth,” 142.
+
+  Optical Effects, Curious, at the Cape, 38.
+
+  Optical Instruments, Late Invention of, 100.
+
+  Oxford and Cambridge, Science at, 1.
+
+
+  Pascal, How he weighed the Atmosphere, 148.
+
+  Pebbles, on, 106.
+
+  Pendulum Experiments, 16-22.
+
+  Pendulum, the Earth weighed by, 200.
+
+  Pendulums, Influence of on each other, 200.
+
+  Perpetual Fire, 117.
+
+  Petrifaction of Human Bodies, 131.
+
+  Phenomena, Mutual Relations of, 4.
+
+  Philosophers’ False Estimates, 5.
+
+  Phosphorescence of Plants, 35.
+
+  Phosphorescence of the Sea, 35.
+
+  Photo-galvanic Engraving, 47.
+
+  Photograph and Stereoscope, 47.
+
+  Photographic effects of Lightning, 45.
+
+  Photographic Surveying, 46.
+
+  Photographs on the Retina, 236.
+
+  Photography, Best Sky for, 45.
+
+  Photography, Magic of, 44.
+
+  Pisa, Leaning Tower of, 15.
+
+  Planetary System, Origin of our, 86.
+
+  Planets, Diversities of, 79.
+
+  Planetoids, List of the, and their Discoverers, 239.
+
+  Plato’s Survey of the Sciences, 2.
+
+  Pleiades, the, 77.
+
+  Plurality of Worlds, 57.
+
+  Polar Ice, Immensity of, 181.
+
+  Polar Iceberg, 180.
+
+  Polarisation of Light, 33.
+
+  Pole, Open Sea at the, 181.
+
+  Pole-Star of 4000 years ago, 76.
+
+  Profitable Science, 139.
+
+  Pterodactyl, the, 130.
+
+  Pyramid, Duration of the, 14.
+
+
+  Quartz, Down of, 42.
+
+
+  Rain, All in the World, 155.
+
+  Rain, an Inch on the Atlantic, 156.
+
+  Rain-Drops, Size of, 154.
+
+  Rain, How the North Wind drives it away, 154.
+
+  Rain, Philosophy of, 153.
+
+  Rainless Districts, 155.
+
+  Rain-making Vapour, from South to North, 152.
+
+  Rainy Climate, Inordinate, 154.
+
+  Red Sea and Mediterranean Levels, 175.
+
+  Red Sea, Colour of, 176.
+
+  Repulsion of Bodies, 216.
+
+  Rhinoceros of Britain, 135.
+
+  River-water on the Ocean, 181.
+
+  Rose, no Fossil, 142.
+
+  Rosse, the Earl of, his “Telescope,” 96-99.
+
+  Rotation-Magnetism discovered, 199.
+
+  Rotation, the Axis of, 11.
+
+
+  St. Paul’s Cathedral, how protected from Lightning, 167.
+
+  Salt, All in the Sea, 179.
+
+  Salt Lake of Utah, 113.
+
+  Salt, Solvent Action of, 115.
+
+  Saltness of the Sea, How to tell, 179.
+
+  Sand in the Hour-glass, 20.
+
+  Sand of the Sea and Desert, 106.
+
+  Saturn’s Ring, Was it known to the Ancients?, 81.
+
+  Schwabe, on Sun-Spots, 68.
+
+  Science at Oxford and Cambridge, 1.
+
+  Science of the Ancient World, 1.
+
+  Science, Theoretical, Practical Results of, 4.
+
+  Sciences, Plato’s Survey of, 2.
+
+  Scientific Treatise, the Earliest English, 5.
+
+  Scoresby, Dr., on the Rosse Telescope, 99.
+
+  Scratches, Colours of, 36.
+
+  Sea, Bottles and Currents at, 172.
+
+  Sea, Bottom of, a burial-place, 177.
+
+  Sea, Circulation of the, 170.
+
+  Sea, Climates of the, 170.
+
+  Sea, Deep, Life of the, 174.
+
+  Sea, Greatest ascertained Depth of, 175.
+
+  Sea, Solitude at, 172.
+
+  Sea, Temperature of the, 170.
+
+  Sea, Why is it Salt?, 177.
+
+  Seas, Primeval, Depth of, 234.
+
+  Sea-breezes and Land-breezes illustrated, 150.
+
+  Sea-milk, What is it?, 176.
+
+  Sea-routes, How shortened, 184.
+
+  Sea-shells and Animalcules, Services of, 234.
+
+  Sea-shells, Why found at Great Heights, 106.
+
+  Sea-water, to imitate, 235.
+
+  Sea-water, Properties of, 179.
+
+  Serapis, Temple of, Successive Changes in, 111.
+
+  Sheep, Geology of the, 138.
+
+  Shells, Geometry of, 232.
+
+  Shells, Hydraulic Theory of, 233.
+
+  Siamese Twins, the, galvanised, 203.
+
+  Skin, Dark Colour of the, 63.
+
+  Smith, William, the Geologist, 126.
+
+  Snow, Absence of in Siberia, 159.
+
+  Snow, Impurity of, 158.
+
+  Snow Phenomenon, 158.
+
+  Snow, Warmth of, in Arctic Latitudes, 158.
+
+  Snow-capped Volcano, the, 119.
+
+  Snow-crystals observed by the Chinese, 159.
+
+  Soap-bubble, Science of the, 48.
+
+  Solar Heat, Extreme, 63.
+
+  Solar System, Velocity of, 59.
+
+  Sound, Figures produced by, 28.
+
+  Sound in rarefied Air, 27.
+
+  Sounding Sand, 27.
+
+  Space, Infinite, 86.
+
+  Speed, Varieties of, 17.
+
+  Spheres, Music of the, 55.
+
+  Spots on the Sun, 67.
+
+  Star, Fixed, the nearest, 78.
+
+  Stars’ Colour, Change in, 77.
+
+  Star’s Light sixteen times that of the Sun, 79.
+
+  Stars, Number of, 75.
+
+  Stars seen by Daylight, 102.
+
+  Stars that have disappeared, 76.
+
+  Stars, Why created, 75.
+
+  Stereoscope and Photograph, 47.
+
+  Stereoscope simplified, 47.
+
+  Storm, Impetus of, 164.
+
+  Storms, Revolving, 164.
+
+  Storms, to tell the Approach of, 163.
+
+  Storm-glass, How to make, 164.
+
+  Succession of life in Time, 128.
+
+  Sun, Actinic Power of, 62.
+
+  Sun and Fixed Stars’ Light compared, 64.
+
+  Sun and Terrestrial Magnetism, 64.
+
+  “Sun Darkened,” 64.
+
+  Sun, Great Size of, on Horizon, 61.
+
+  Sun, Heating Power of, 62.
+
+  Sun, Lost Heat of, 103.
+
+  Sun, Luminous Disc of, 60.
+
+  Sun, Nature of the, 59, 238.
+
+  Sun, Spots on, 67.
+
+  Sun, Translatory Motion of, 61.
+
+  Sun’s Distance by the Yard Measure, 66.
+
+  Sun’s Heat, Is it decreasing?, 65.
+
+  Sun’s Rays increasing the Strength of Magnets, 196.
+
+  Sun’s Light and Terrestrial Lights, 61.
+
+  Sun-dial, Universal, 65.
+
+
+  Telegraph, the Atlantic, 226.
+
+  Telegraph, the Electric, 220.
+
+  Telescope and Microscope, the, 38.
+
+  Telescope, Galileo’s, 93.
+
+  Telescope, Herschel’s, 95.
+
+  Telescope, Newton’s first Reflecting, 94.
+
+  Telescopes, Antiquity of, 94.
+
+  Telescopes, Gigantic, proposed, 99.
+
+  Telescopes, the Earl of Rosse’s, 96.
+
+  Temperature and Electricity, 208.
+
+  Terrestrial Magnetism, Origin of, 200.
+
+  Thames, the, and its Salt-water Bed, 182.
+
+  Threads, the two Electric, 215.
+
+  Thunderstorm seen from a Balloon, 169.
+
+  Tides, How produced by Sun and Moon, 66.
+
+  Time an Element of Force, 19.
+
+  Time, Minute Measurement of, 194.
+
+  Topaz, Transmutation of, 37.
+
+  Trilobite, the, 138.
+
+  Tuning-fork a Flute-player, 28.
+
+  Twilight, Beauty of, 148.
+
+
+  Universe, Vast Numbers in, 75.
+
+  Utah, Salt Lake of, 113.
+
+
+  Velocity of the Solar System, 59.
+
+  Vesta and Pallas, Speculations on, 82.
+
+  Vesuvius, Great Eruptions of, 119.
+
+  Vibration of Heated Metals, 188.
+
+  Visibility of Objects, 30.
+
+  Voice, Human, Audibility of, 27.
+
+  Volcanic Action and Geological Change, 118.
+
+  Volcanic Dust, Travels of, 119.
+
+  Volcanic Islands, Disappearance of, 117.
+
+  Voltaic Battery and the Gymnotus, 206.
+
+  Voltaic Currents in Mines, 206.
+
+  Voltaic Electricity discovered, 205.
+
+
+  Watches, Harrison’s Prize, 229.
+
+  Water decomposed by Electricity, 208.
+
+  Water, Running, Force of, 114.
+
+  Waters of the Globe gradually decreasing, 113.
+
+  Water-Purifiers, Natural, 234.
+
+  Waterspouts, How formed in the Java Sea, 160.
+
+  Waves, Cause of, 183.
+
+  Waves, Force of, 184.
+
+  Waves, Rate of Travelling, 183.
+
+  Wenham-Lake Ice, Purity of, 161.
+
+  West, Superior Salubrity of, 150.
+
+  “White Water,” and Luminous Animals at Sea, 173.
+
+  Winds, Transporting Power of, 163.
+
+  Wollaston’s Minute Battery, 204.
+
+  World, All the, in Motion, 11.
+
+  World, the, in a Nutshell, 13.
+
+  Worlds, More than One, 56.
+
+  Worlds to come, 58.
+
+
+LONDON: ROBSON, LEVEY, AND FRANKLYN, GREAT NEW STREET AND PETTER LANE,
+E.C.
+
+
+
+
+Transcriber’s Notes
+
+
+Punctuation, hyphenation, and spelling were made consistent when a
+predominant preference was found in this book; otherwise they were not
+changed.
+
+Simple typographical errors were corrected; occasional unbalanced
+quotation marks retained.
+
+Ambiguous hyphens at the ends of lines were retained.
+
+Some numbers in equations include a hyphen to separate the fractional
+and integer parts. These are not minus signs, which, like other
+arithmetic operators, are surrounded by spaces.
+
+The original book apparently used a smaller font for multiple reasons,
+but as those reasons were not always clear to the Transcriber, smaller
+text is indented by 2 spaces in the Plain Text version of this eBook,
+and is displayed smaller in other versions.
+
+Footnotes, originally at the bottoms of pages, have been collected and
+repositioned just before the Index.
+
+Page 59: “95 × 1·623 = 154·185” was misprinted as “95 + 1·623 =
+154·185” and has been corrected here.
+
+The Table of Contents does not list the “Phenomena of Heat” chapter,
+which begins on page 185; nor the Index, which begins on page 242.
+
+Page 95: “adjustible” was printed that way.
+
+Page 151: Missing closing quotation mark added after “rapidly evaporate
+in space.” It may belong elsewhere.
+
+Page 221: Missing closing quotation mark not added for phrase beginning
+“it is a fine invention”.
+
+
+
+
+
+
+
+End of the Project Gutenberg EBook of Curiosities of Science, Past and
+Present, by John Timbs
+
+*** END OF THE PROJECT GUTENBERG EBOOK 48516 ***
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-<pre>

-

-Project Gutenberg's Curiosities of Science, Past and Present, by John Timbs

-

-This eBook is for the use of anyone anywhere in the United States and most

-other parts of the world 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.  If you are not located in the United States, you'll have

-to check the laws of the country where you are located before using this ebook.

-

-Title: Curiosities of Science, Past and Present

-       A Book for Old and Young

-

-Author: John Timbs

-

-Release Date: March 17, 2015 [EBook #48516]

-

-Language: English

-

-Character set encoding: UTF-8

-

-*** START OF THIS PROJECT GUTENBERG EBOOK CURIOSITIES OF SCIENCE, PAST, PRESENT ***

-

-

-

-

-Produced by Chris Curnow, Charlie Howard, and the Online

-Distributed Proofreading Team at http://www.pgdp.net (This

-file was produced from images generously made available

-by The Internet Archive)

-

-

-

-

-

-

-</pre>

-

-

-<div class="poem-container">

-<div class="iblock" style="max-width: 30em; border: thin solid black; padding: 1em;">

-<p class="center larger" style="font-family: sans-serif, serif;">

-NEW WORK ON PAINTING.</p>

-

-<p class="p1 center"><i>Just ready, in small 8vo, with Frontispiece and Vignette</i>,</p>

-

-<p class="p1 center large vspace wspace">PAINTING

-POPULARLY EXPLAINED;</p>

-

-<p class="p1 center vspace"><span class="smaller">WITH</span><br />

-<span class="larger">The Practice of the Art,</span><br />

-<span class="smaller">AND</span><br />

-<span class="larger">HISTORICAL NOTICES OF ITS PROGRESS.</span></p>

-

-<p class="center"><span class="smaller">BY</span><br />

-<span class="larger">THOMAS J. GULLICK, <span class="smcap">Painter</span>,</span><br />

-<span class="smaller">AND</span><br />

-<span class="larger">JOHN TIMBS, F.S.A.</span>

-</p>

-

-<p class="p2">The plan of this work is thus sketched in the <i>Introduction</i>:</p>

-

-<blockquote>

-

-<p>“There have been in the history of Art, four grand styles of

-imitating Nature&mdash;Tempera, Encaustic, Fresco, and Oil. These,

-together with the minor modes of Painting, we propose arranging

-in something like chronological sequence; but our design being to

-offer an explanation of the Art derived from practical acquaintance,

-rather than attempt to give its history, we shall confine ourselves

-for the most part to so much only of the History of Painting as is

-necessary to elucidate the origin of the different practices which have

-obtained at different periods.”</p>

-

-<p>By this means, the Authors hope to produce a work which may

-be valuable to the Amateur, and interesting to the Connoisseur, the

-Artist, and the General Reader.</p></blockquote>

-

-<p class="p1 larger center"><span class="gesperrt">LONDON:</span><br />

-KENT &amp; CO. (<span class="smcap smaller">late Bogue</span>), FLEET STREET.</p>

-</div></div>

-

-<div class="newpage p4">

-<div class="figcenter" style="width: 450px;">

-<img src="images/i_frontis.jpg" width="392" height="600" alt="" />

-<div class="caption"><p>MOUTH OF THE GREAT ROSSE TELESCOPE, AT PARSONSTOWN.</p>

-

-<p>FROM A PHOTOGRAPH.</p></div>

-</div></div>

-

-<hr />

-

-<p class="newpage p4 center large vspace wspace">

-Things not generally Known<br />

-Familiarly Explained.</p>

-

-<h1 class="vspace wspace">CURIOSITIES OF SCIENCE,<br />

-<span class="small">Past and Present.<br />

-A BOOK FOR OLD AND YOUNG.</span></h1>

-

-<p class="p2 center"><span class="smcap">By</span> JOHN TIMBS, F.S.A.</p>

-

-<p class="p1 center small">AUTHOR OF THINGS NOT GENERALLY KNOWN; AND EDITOR OF THE<br />

-YEAR-BOOK OF FACTS.</p>

-

-<div class="p2 figcenter" style="width: 450px;">

-<img src="images/i_vignette.jpg" width="300" height="286" alt="" />

-<div class="caption"><p>Model of the Safety-Lamp, made by Sir Humphry Davy’s own hands;<br />

-in the possession of the Royal Society.</p></div>

-</div>

-

-<p class="p2 center">

-LONDON:<br />

-KENT AND CO. (<span class="smcap">late BOGUE</span>), FLEET STREET.<br />

-MDCCCLVIII.

-</p>

-

-<hr />

-

-<p class="newpage p4 center">

-<i>The Author reserves the right of authorising a Translation of this Work.</i></p>

-

-<p class="p2 center small vspace">LONDON:<br />

-PRINTED BY LEVEY, ROBSON, AND FRANKLYN,<br />

-Great New Street and Fetter Lane.

-</p>

-

-<hr />

-

-<div class="chapter"></div>

-<p class="newpage p4 in0 in4">

-<span class="smcap">Gentle Reader</span>,

-</p>

-

-<p>The volume of “<span class="smcap">Curiosities</span>” which I here present to your

-notice is a portion of the result of a long course of reading, observation,

-and research, necessary for the compilation of thirty volumes

-of “Arcana of Science” and “Year-Book of Facts,” published

-from 1828 to 1858. Throughout this period&mdash;nearly half of the

-Psalmist’s “days of our years”&mdash;I have been blessed with health

-and strength to produce these volumes, year by year (with one

-exception), upon the appointed day; and this with unbroken attention

-to periodical duties, frequently rendered harassing or

-ungenial. Nevertheless, during these three decades I have found

-my account in the increasing approbation of the reading public,

-which has been so largely extended to the series of “<span class="smcap">Things not

-generally Known</span>,” of which the present volume of “<span class="smcap">Curiosities

-of Science</span>” is an instalment. I need scarcely add, that in its progressive

-preparation I have endeavoured to compare, weigh, and

-consider, the contents, so as to combine the experience of the Past

-with the advantages of the Present.</p>

-

-<p>In these days of universal attainments, when Science becomes

-not merely a luxury to the rich, but bread to the poor, and when

-the very amusements as well as the conveniences of life have taken

-a scientific colour, it is reasonable to hope that the present volume

-may be acceptable to a large class of seekers after “things not

-generally known.” For this purpose, I have aimed at soundness as

-well as popularity; although, for myself, I can claim little beyond

-being one of those industrious “ants of science” who garner facts,

-and by selection and comparison adapt them for a wider circle of

-readers than they were originally expected to reach. In each case,

-as far as possible, these “<span class="smcap">Curiosities</span>” bear the mint-mark of authority;

-and in the living list are prominent the names of Humboldt

-and Herschel, Airy and Whewell, Faraday, Brewster, Owen, and

-Agassiz, Maury, Wheatstone, and Hunt, from whose writings and

-researches the following pages are frequently enriched.</p>

-

-<p>The sciences here illustrated are, in the main, Astronomy and

-Meteorology; Geology and Paleontology; Physical Geography;

-Sound, Light, and Heat; Magnetism and Electricity,&mdash;the latter

-with special attention to the great marvel of our times, the Electro-magnetic

-Telegraph. I hope, at no very distant period, to extend

-the “<span class="smcap">Curiosities</span>” to another volume, to include branches of

-Natural and Experimental Science which are not here presented.</p>

-

-<p class="sigright">

-I. T.</p>

-

-<p><i>November 1858.</i></p>

-

-<hr />

-

-<div class="chapter"></div>

-<h2><a name="CONTENTS" id="CONTENTS"></a>CONTENTS.</h2>

-

-<table class="vspace" summary="Contents">

-  <tr class="small">

-    <td> </td>

-    <td class="tdr">PAGE</td></tr>

-  <tr>

-    <td class="tdl"><span class="smcap">Introductory</span></td>

-    <td class="tdr"><a href="#Introductory">1&ndash;10</a></td></tr>

-  <tr>

-    <td class="tdl"><span class="smcap">Physical Phenomena</span></td>

-    <td class="tdr"><a href="#Physical">11&ndash;26</a></td></tr>

-  <tr>

-    <td class="tdl"><span class="smcap">Sound and Light</span></td>

-    <td class="tdr"><a href="#Sound">27&ndash;53</a></td></tr>

-  <tr>

-    <td class="tdl"><span class="smcap">Astronomy</span></td>

-    <td class="tdr"><a href="#Astronomy">54&ndash;103</a></td></tr>

-  <tr>

-    <td class="tdl"><span class="smcap">Geology and Paleontology</span></td>

-    <td class="tdr"><a href="#Geology">104&ndash;145</a></td></tr>

-  <tr>

-    <td class="tdl"><span class="smcap">Meteorological Phenomena</span></td>

-    <td class="tdr"><a href="#Meteorological">146&ndash;169</a></td></tr>

-  <tr>

-    <td class="tdl"><span class="smcap">Physical Geography of the Sea</span></td>

-    <td class="tdr"><a href="#Geography">170&ndash;192</a></td></tr>

-  <tr>

-    <td class="tdl"><span class="smcap">Magnetism and Electricity</span></td>

-    <td class="tdr"><a href="#Magnetism">193&ndash;219</a></td></tr>

-  <tr>

-    <td class="tdl"><span class="smcap">The Electric Telegraph</span></td>

-    <td class="tdr"><a href="#Electric">220&ndash;228</a></td></tr>

-  <tr>

-    <td class="tdl"><span class="smcap">Miscellanea</span></td>

-    <td class="tdr"><a href="#Miscellanea">229&ndash;241</a></td></tr>

-</table>

-

-<hr />

-

-<p><span class="pagenum"><a name="Page_vii" id="Page_vii">vii</a></span></p>

-

-<div class="chapter"></div>

-<h2><a name="The_Frontispiece" id="The_Frontispiece"></a>The Frontispiece.</h2>

-

-<h3>THE GREAT ROSSE TELESCOPE.</h3>

-

-<p>The originator and architect of this magnificent instrument had long

-been distinguished in scientific research as Lord Oxmantown; and may

-be considered to have gracefully commemorated his succession to the

-Earldom of Rosse, and his Presidency of the Royal Society, by the completion

-of this marvellous work, with which his name will be hereafter

-indissolubly associated.</p>

-

-<p>The Great Reflecting Telescope at Birr Castle (of which the Frontispiece

-represents a portion<a name="FNanchor_1" id="FNanchor_1" href="#Footnote_1" class="fnanchor">1</a>) will be found fully described at pp. 96&ndash;99

-of the present volume of <i>Curiosities of Science</i>.</p>

-

-<p>This matchless instrument has already disclosed “forms of stellar

-arrangement indicating modes of dynamic action never before contemplated

-in celestial mechanics.” “In these departments of research,&mdash;the

-examination of the configurations of nebulæ, and the resolution of

-nebulæ into stars (says the Rev. Dr. Scoresby),&mdash;the six-feet speculum

-has had its grandest triumphs, and the noble artificer and observer the

-highest rewards of his talents and enterprise. Altogether, the quantity

-of work done during a period of about seven years&mdash;including a

-winter when a noble philanthropy for a starving population absorbed the

-keenest interests of science&mdash;has been decidedly great; and the new

-knowledge acquired concerning the handiwork of the great Creator

-amply satisfying of even sanguine expectation.”</p>

-

-<hr />

-<div class="chapter"></div>

-<h2><a name="The_Vignette" id="The_Vignette"></a>The Vignette.</h2>

-

-<h3>SIR HUMPHRY DAVY’S OWN MODEL OF HIS SAFETY-LAMP.</h3>

-

-<p>Of the several contrivances which have been proposed for safely lighting

-coal-mines subject to the visitation of fire-damp, or carburetted

-hydrogen, the Safety-Lamp of Sir Humphry Davy is the only one which

-has ever been judged safe, and been extensively employed. The inventor

-first turned his attention to the subject in 1815, when Davy

-began a minute chemical examination of fire-damp, and found that it

-required an admixture of a large quantity of atmospheric air to render

-it explosive. He then ascertained that explosions of inflammable gases

-were incapable of being passed through long narrow metallic tubes,

-and that this principle of security was still obtained by diminishing

-their length and increasing their number. This fact led to trials upon

-sieves made of wire-gauze; when Davy found that if a piece of wire-gauze

-was held over the flame of a lamp, or of coal-gas, it prevented

-the flame from passing; and he ascertained that a flame confined in a

-cylinder of very fine wire-gauze did not explode even in a mixture of

-oxygen and hydrogen, but that the gases burnt in it with great vivacity.</p>

-

-<p>These experiments served as the basis of the Safety-Lamp. The

-apertures in the gauze, Davy tells us in his work on the subject, should

-not be more than 1/22d of an inch square. The lamp is screwed on to

-the bottom of the wire-gauze cylinder. When it is lighted, and gradually

-introduced into an atmosphere mixed with fire-damp, the size and

-length of the flame are first increased. When the inflammable gas forms

-as much as 1/12th of the volume of air, the cylinder becomes filled with a

-feeble blue flame, within which the flame of the wick burns brightly, and

-the light of the wick continues till the fire-damp increases to 1/6th or 1/5th;<span class="pagenum"><a name="Page_viii" id="Page_viii">viii</a></span>

-it is then lost in the flame of the fire-damp, which now fills the cylinder

-with a pretty strong light; and when the foul air constitutes one-third

-of the atmosphere it is no longer fit for respiration,&mdash;and this ought to

-be a signal to the miner to leave that part of the workings.</p>

-

-<p>Sir Humphry Davy presented his first communication respecting

-his discovery of the Safety-Lamp to the Royal Society in 1815. This

-was followed by a series of papers remarkable for their simplicity and

-clearness, crowned by that read on the 11th of January 1816, when the

-principle of the Safety-Lamp was announced, and Sir Humphry presented

-to the Society a model made by his own hands, which is to this

-day preserved in the collection of the Royal Society at Burlington House.

-From this interesting memorial the Vignette has been sketched.</p>

-

-<p>There have been several modifications of the Safety-Lamp, and the

-merit of the discovery has been claimed by others, among whom was

-Mr. George Stephenson; but the question was set at rest forty-one

-years since by an examination,&mdash;attested by Sir Joseph Banks, P.R.S.,

-Mr. Brande, Mr. Hatchett, and Dr. Wollaston,&mdash;and awarding the independent

-merit to Davy.</p>

-

-<p>A more substantial, though not a more honourable, testimony of

-approval was given by the coal-owners, who subscribed 2500<i>l.</i> to purchase

-a superb service of plate, which was suitably inscribed and presented

-to Davy.<a name="FNanchor_2" id="FNanchor_2" href="#Footnote_2" class="fnanchor">2</a></p>

-

-<p>Meanwhile the Report by the Parliamentary Committee “cannot

-admit that the experiments (made with the Lamp) have any tendency

-to detract from the character of Sir Humphry Davy, or to disparage

-the fair value placed by himself upon his invention. The improvements

-are probably those which longer life and additional facts would have

-induced him to contemplate as desirable, and of which, had he not been

-the inventor, he might have become the patron.”</p>

-

-<p>The principle of the invention may be thus summed up. In the

-Safety-Lamp, the mixture of the fire-damp and atmospheric air within

-the cage of wire-gauze explodes upon coming in contact with the flame;

-but the combustion cannot pass through the wire-gauze, and being there

-imprisoned, cannot impart to the explosive atmosphere of the mine any

-of its force. This effect has been erroneously attributed to a cooling

-influence of the metal.</p>

-

-<p>Professor Playfair has eloquently described the Safety-Lamp of Davy

-as a present from philosophy to the arts; a discovery in no degree the

-effect of accident or chance, but the result of patient and enlightened

-research, and strongly exemplifying the great use of an immediate and

-constant appeal to experiment. After characterising the invention as

-the <i>shutting-up in a net of the most slender texture</i> a most violent and

-irresistible force, and a power that in its tremendous effects seems to

-emulate the lightning and the earthquake, Professor Playfair thus concludes:

-“When to this we add the beneficial consequences, and the

-saving of the lives of men, and consider that the effects are to remain

-as long as coal continues to be dug from the bowels of the earth, it may

-be fairly said that there is hardly in the whole compass of art or science

-a single invention of which one would rather wish to be the author....

-This,” says Professor Playfair, “is exactly such a case as we should

-choose to place before Bacon, were he to revisit the earth; in order to

-give him, in a small compass, an idea of the advancement which philosophy

-has made since the time when he had pointed out to her the

-route which she ought to pursue.”</p>

-

-<hr />

-

-<p><span class="pagenum"><a name="Page_1" id="Page_1">1</a></span></p>

-

-<div class="chapter"></div>

-<h2><span class="larger">CURIOSITIES OF SCIENCE.</span></h2>

-

-<h2 class="nobreak"><a name="Introductory" id="Introductory"></a>Introductory.</h2>

-

-<h3>SCIENCE OF THE ANCIENT WORLD.</h3>

-

-<p>In every province of human knowledge where we now possess

-a careful and coherent interpretation of nature, men began by

-attempting in bold flights to leap from obvious facts to the

-highest point of generality&mdash;to some wide and simple principle

-which after-ages had to reject. Thus, from the facts that all

-bodies are hot or cold, moist or dry, they leapt at once to the

-doctrine that the world is constituted of four elements&mdash;earth,

-air, fire, water; from the fact that the heavenly bodies circle

-the sky in courses which occur again and again, they at once

-asserted that they move in exact circles, with an exactly uniform

-motion; from the fact that heavy bodies fall through the

-air somewhat faster than light ones, it was assumed that all

-bodies fall quickly or slowly exactly in proportion to their

-weight; from the fact that the magnet attracts iron, and that

-this force of attraction is capable of increase, it was inferred

-that a perfect magnet would have an irresistible force of attraction,

-and that the magnetic pole of the earth would draw

-the nails out of a ship’s bottom which came near it; from the

-fact that some of the finest quartz crystals are found among

-the snows of the Alps, it was inferred that the crystallisation

-of gems is the result of intense and long-continued cold: and

-so on in innumerable instances. Such anticipations as these

-constituted the basis of almost all the science of the ancient

-world; for such principles being so assumed, consequences were

-drawn from them with great ingenuity, and systems of such

-deductions stood in the place of science.&mdash;<i>Edinburgh Review</i>,

-No. 216.</p>

-

-<h3>SCIENCE AT OXFORD AND CAMBRIDGE.</h3>

-

-<p>The earliest science of a decidedly English school is due,

-for the most part, to the University of Oxford, and specially

-to Merton College,&mdash;a foundation of which Wood remarks, that<span class="pagenum"><a name="Page_2" id="Page_2">2</a></span>

-there was no other for two centuries, either in Oxford or Paris,

-which could at all come near it in the cultivation of the sciences.

-But he goes on to say that large chests full of the

-writers of this college were allowed to remain untouched by

-their successors for fear of the magic which was supposed to be

-contained in them. Nevertheless, it is not difficult to trace

-the liberalising effect of scientific study upon the University in

-general, and Merton College in particular; and it must be

-remembered that to the cultivation of the mind at Oxford we

-owe almost all the literary celebrity of the middle ages. In

-this period the University of Cambridge appears to have acquired

-no scientific distinction. Taking as a test the acquisition

-of celebrity on the continent, we find that Bacon, Sacrobosco,

-Greathead, Estwood, &amp;c. were all of Oxford. The

-latter University had its morning of splendour while Cambridge

-was comparatively unknown; it had also its noonday, illustrated

-by such men as Briggs, Wren, Wallis, Halley, and

-Bradley.</p>

-

-<p>The age of science at Cambridge may be said to have begun

-with Francis Bacon; and but that we think much of the difference

-between him and his celebrated namesake lies more in

-time and circumstances than in talents or feelings, we would

-rather date from 1600 with the former than from 1250 with

-the latter. Praise or blame on either side is out of the question,

-seeing that the earlier foundation of Oxford, and its

-superiority in pecuniary means, rendered all that took place

-highly probable; and we are in a great measure indebted for

-the liberty of writing our thoughts, to the cultivation of the

-liberalising sciences at Oxford in the dark ages.</p>

-

-<p>With regard to the University of Cambridge, for a long

-time there hardly existed the materials of any proper instruction,

-even to the extent of pointing out what books should be

-read by a student desirous of cultivating astronomy.</p>

-

-<h3>PLATO’S SURVEY OF THE SCIENCES.</h3>

-

-<blockquote>

-

-<p>Plato, like Francis Bacon, took a review of the sciences of his time:

-he enumerates arithmetic and plane geometry, treated as collections

-of abstract and permanent truths; solid geometry, which he “notes

-as deficient” in his time, although in fact he and his school were in

-possession of the doctrine of the “five regular solids;” astronomy, in

-which he demands a science which should be elevated above the mere

-knowledge of phenomena. The visible appearances of the heavens

-only suggest the problems with which true astronomy deals; as beautiful

-geometrical diagrams do not prove, but only suggest geometrical

-propositions. Finally, Plato notices the subject of harmonics, in which

-he requires a science which shall deal with truths more exact than the

-ear can establish, as in astronomy he requires truths more exact than

-the eye can assure us of.</p>

-

-<p>In a subsequent paper Plato speaks of <i>Dialectic</i> as a still higher<span class="pagenum"><a name="Page_3" id="Page_3">3</a></span>

-element of a philosophical education, fitted to lead men to the knowledge

-of real existences and of the supreme good. Here he describes

-dialectic by its objects and purpose. In other places dialectic is spoken

-of as a method or process of analysis; as in the <i>Phædrus</i>, where Socrates

-describes a good dialectician as one who can divide a subject according

-to its natural members, and not miss the joint, like a bad carver.

-Xenophon says that Socrates derived <i>dialectic</i> from a term implying

-to <i>divide a subject into parts</i>, which Mr. Grote thinks unsatisfactory as

-an etymology, but which has indicated a practical connection in the

-Socratic school. The result seems to be that Plato did not establish

-any method of analysis of a subject as his dialectic; but he conceived

-that the analytical habits formed by the comprehensive study of the

-exact sciences, and sharpened by the practice of dialogue, would lead

-his students to the knowledge of first principles.&mdash;<i>Dr. Whewell.</i></p></blockquote>

-

-<h3>FOLLY OF ATHEISM.</h3>

-

-<p>Morphology, in natural science, teaches us that the whole

-animal and vegetable creation is formed upon certain fundamental

-types and patterns, which can be traced under various

-modifications and transformations through all the rich variety

-of things apparently of most dissimilar build. But here and

-there a scientific person takes it into his foolish head that there

-may be a set of moulds without a moulder, a calculated gradation

-of forms without a calculator, an ordered world without

-an ordering God. Now, this atheistical science conveys about

-as much meaning as suicidal life: for science is possible only

-where there are ideas, and ideas are only possible where there

-is mind, and minds are the offspring of God; and atheism

-itself is not merely ignorance and stupidity,&mdash;it is the purely

-nonsensical and the unintelligible.&mdash;<i>Professor Blackie</i>; <i>Edinburgh

-Essays</i>, 1856.</p>

-

-<h3>THE ART OF OBSERVATION.</h3>

-

-<p>To observe properly in the very simplest of the physical

-sciences requires a long and severe training. No one knows

-this so feelingly as the great discoverer. Faraday once said,

-that he always doubts his own observations. Mitscherlich on

-one occasion remarked to a man of science that it takes

-fourteen years to discover and establish a single new fact in

-chemistry. An enthusiastic student one day betook himself to

-Baron Cuvier with the exhibition of a new organ&mdash;a muscle

-which he supposed himself to have discovered in the body of

-some living creature or other; but the experienced and sagacious

-naturalist kindly bade the young man return to him with

-the same discovery in six months. The Baron would not even

-listen to the student’s demonstration, nor examine his dissection,

-till the eager and youthful discoverer had hung over the

-object of inquiry for half a year; and yet that object was a

-mere thing of the senses.&mdash;<i>North-British Review</i>, No. 18.</p>

-

-<p><span class="pagenum"><a name="Page_4" id="Page_4">4</a></span></p>

-

-<h3>MUTUAL RELATIONS OF PHENOMENA.</h3>

-

-<p>In the observation of a phenomenon which at first sight

-appears to be wholly isolated, how often may be concealed the

-germ of a great discovery! Thus, when Galvani first stimulated

-the nervous fibre of the frog by the accidental contact of

-two heterogeneous metals, his contemporaries could never have

-anticipated that the action of the voltaic pile would discover

-to us in the alkalies metals of a silver lustre, so light as to

-swim on water, and eminently inflammable; or that it would

-become a powerful instrument of chemical analysis, and at the

-same time a thermoscope and a magnet. When Huyghens first

-observed, in 1678, the phenomenon of the polarisation of light,

-exhibited in the difference between two rays into which a pencil

-of light divides itself in passing through a doubly refracting

-crystal, it could not have been foreseen that a century and a

-half later the great philosopher Arago would, by his discovery of

-<i>chromatic polarisation</i>, be led to discern, by means of a small fragment

-of Iceland spar, whether solar light emanates from a solid

-body or a gaseous covering; or whether comets transmit light

-directly, or merely by reflection.&mdash;<i>Humboldt’s Cosmos</i>, vol. i.</p>

-

-<h3>PRACTICAL RESULTS OF THEORETICAL SCIENCE.</h3>

-

-<p>What are the great wonders, the great sources of man’s

-material strength, wealth, and comfort in modern times? The

-Railway, with its mile-long trains of men and merchandise,

-moving with the velocity of the wind, and darting over chasms

-a thousand feet wide; the Electric Telegraph, along which

-man’s thoughts travel with the velocity of light, and girdle the

-earth more quickly than Puck’s promise to his master; the

-contrivance by which the Magnet, in the very middle of a strip

-of iron, is still true to the distant pole, and remains a faithful

-guide to the mariner; the Electrotype process, by which a

-metallic model of any given object, unerringly exact, grows

-into being like a flower. Now, all these wonders are the result

-of recent and profound discoveries in theoretical science. The

-Locomotive Steam-engine, and the Steam-engine in all its other

-wonderful and invaluable applications, derives its efficacy from

-the discoveries, by Watt and others, of the laws of steam. The

-Railway Bridge is not made strong by mere accumulation of

-materials, but by the most exact and careful scientific examination

-of the means of giving the requisite strength to every

-part, as in the great example of Mr. Stephenson’s Britannia

-Bridge over the Menai Strait. The Correction of the Magnetic

-Needle in iron ships it would have been impossible for Mr.

-Airy to secure without a complete theoretical knowledge of<span class="pagenum"><a name="Page_5" id="Page_5">5</a></span>

-the laws of Magnetism. The Electric Telegraph and the Electrotype

-process include in their principles and mechanism the

-most complete and subtle results of electrical and magnetical

-theory.&mdash;<i>Edinburgh Review</i>, No. 216.</p>

-

-<h3>PERPETUITY OF IMPROVEMENT.</h3>

-

-<p>In the progress of society all great and real improvements

-are perpetuated: the same corn which, four thousand years

-ago, was raised from an improved grass by an inventor worshiped

-for two thousand years in the ancient world under the

-name of Ceres, still forms the principal food of mankind; and

-the potato, perhaps the greatest benefit that the old has derived

-from the new world, is spreading over Europe, and will continue

-to nourish an extensive population when the name of the

-race by whom it was first cultivated in South America is forgotten.&mdash;<i>Sir

-H. Davy.</i></p>

-

-<h3>THE EARLIEST ENGLISH SCIENTIFIC TREATISE.</h3>

-

-<p>Geoffrey Chaucer, the poet, wrote a treatise on the Astrolabe

-for his son, which is the earliest English treatise we have

-met with on any scientific subject. It was not completed; and

-the apologies which Chaucer makes to his own child for writing

-in English are curious; while his inference that his son should

-therefore “pray God save the king that is lord of this language,”

-is at least as loyal as logical.</p>

-

-<h3>PHILOSOPHERS’ FALSE ESTIMATES OF THEIR OWN LABOURS.</h3>

-

-<p>Galileo was confident that the most important part of his

-contributions to the knowledge of the solar system was his

-Theory of the Tides&mdash;a theory which all succeeding astronomers

-have rejected as utterly baseless and untenable. Descartes

-probably placed far above his beautiful explanation of

-the rainbow, his <i>à priori</i> theory of the existence of the vortices

-which caused the motion of the planets and satellites. Newton

-perhaps considered as one of the best parts of his optical

-researches his explanation of the natural colour of bodies,

-which succeeding optical philosophers have had to reject; and

-he certainly held very strongly the necessity of a material cause

-for gravity, which his disciples have disregarded. Davy looked

-for his greatest triumph in the application of his discoveries to

-prevent the copper bottoms of ships from being corroded. And

-so in other matters.&mdash;<i>Edinburgh Review</i>, No. 216.</p>

-

-<h3>RELICS OF GENIUS.</h3>

-

-<p>Professor George Wilson, in a lecture to the Scottish Society

-of Arts, says: “The spectacle of these things ministers<span class="pagenum"><a name="Page_6" id="Page_6">6</a></span>

-only to the good impulses of humanity. Isaac Newton’s telescope

-at the Royal Society of London; Otto Guericke’s air-pump

-in the Library at Berlin; James Watt’s repaired Newcomen

-steam-engine in the Natural-Philosophy class-room of

-the College at Glasgow; Fahrenheit’s thermometer in the corresponding

-class-room of the University of Edinburgh; Sir H.

-Davy’s great voltaic battery at the Royal Institution, London,

-and his safety-lamp at the Royal Society; Joseph Black’s

-pneumatic trough in Dr. Gregory’s possession; the first wire

-which Faraday made rotate electro-magnetically, at St. Bartholomew’s

-Hospital; Dalton’s atomic models at Manchester;

-and Kemp’s liquefied gases in the Industrial Museum of Scotland,&mdash;are

-alike personal relics, historical monuments, and

-objects of instruction, which grow more and more precious

-every year, and of which we never can have too many.”</p>

-

-<h3>THE ROYAL SOCIETY: THE NATURAL AND SUPERNATURAL.</h3>

-

-<p>The Royal Society was formed with the avowed object of

-increasing knowledge by direct experiment; and it is worthy

-of remark, that the charter granted by Charles II. to this celebrated

-institution declares that its object is the extension of

-natural knowledge, as opposed to that which is supernatural.</p>

-

-<p>Dr. Paris (<i>Life of Sir H. Davy</i>, vol. ii. p. 178) says: “The

-charter of the Royal Society states that it was established for

-the improvement of <i>natural</i> science. This epithet <i>natural</i> was

-originally intended to imply a meaning, of which very few

-persons, I believe, are aware. At the period of the establishment

-of the society, the arts of witchcraft and divination were

-very extensively encouraged; and the word <i>natural</i> was therefore

-introduced in contradistinction to <i>supernatural</i>.”</p>

-

-<h3>THE PHILOSOPHER BOYLE.</h3>

-

-<p>After the death of Bacon, one of the most distinguished

-Englishmen was certainly Robert Boyle, who, if compared

-with his contemporaries, may be said to rank immediately

-below Newton, though of course very inferior to him as an original

-thinker. Boyle was the first who instituted exact experiments

-into the relation between colour and heat; and by

-this means not only ascertained some very important facts,

-but laid a foundation for that union between optics and thermotics,

-which, though not yet completed, now merely waits

-for some great philosopher to strike out a generalisation large

-enough to cover both, and thus fuse the two sciences into a

-single study. It is also to Boyle, more than to any other Englishman,

-that we owe the science of hydrostatics in the state<span class="pagenum"><a name="Page_7" id="Page_7">7</a></span>

-in which we now possess it.<a name="FNanchor_3" id="FNanchor_3" href="#Footnote_3" class="fnanchor">3</a> He is also the original discoverer

-of that beautiful law, so fertile in valuable results, according

-to which the elasticity of air varies as its density. And, in

-the opinion of one of the most eminent modern naturalists, it

-was Boyle who opened up those chemical inquiries which went

-on accumulating until, a century later, they supplied the

-means by which Lavoisier and his contemporaries fixed the

-real basis of chemistry, and enabled it for the first time to

-take its proper stand among those sciences that deal with the

-external world.&mdash;<i>Buckle’s History of Civilization</i>, vol. i.</p>

-

-<h3>SIR ISAAC NEWTON’S ROOMS AND LABORATORY IN TRINITY

-COLLEGE, CAMBRIDGE.</h3>

-

-<p>Of the rooms occupied by Newton during his early residence

-at Cambridge, it is now difficult to settle the locality.

-The chamber allotted to him as Fellow, in 1667, was “the

-Spiritual Chamber,” conjectured to have been the ground-room,

-next the chapel, but it is not certain that he resided

-there. The rooms in which he lived from 1682 till he left

-Cambridge, are in the north-east corner of the great court,

-on the first floor, on the right or north of the gateway or

-principal entrance to the college. His laboratory, as Dr.

-Humphrey Newton tell us, was “on the left end of the garden,

-near the east end of the chapel; and his telescope (refracting)

-was five feet long, and placed at the head of the stairs, going

-down into the garden.”<a name="FNanchor_4" id="FNanchor_4" href="#Footnote_4" class="fnanchor">4</a> The east side of Newton’s rooms has

-been altered within the last fifty years: Professor Sedgwick,

-who came up to college in 1804, recollects a wooden room,

-supported on an arcade, shown in Loggan’s view, in place of

-which arcade is now a wooden wall and brick chimney.</p>

-

-<blockquote>

-

-<p>Dr. Humphrey Newton relates that in college Sir Isaac very rarely

-went to bed till two or three o’clock in the morning, sometimes not till

-five or six, especially at spring and fall of the leaf, when he used to

-employ about six weeks in his laboratory, the fire scarcely going out

-either night or day; he sitting up one night, and Humphrey another,

-till he had finished his chemical experiments. Dr. Newton describes

-the laboratory as “well furnished with chymical materials, as bodyes,

-receivers, heads, crucibles, &amp;c., which was made very little use of, y<sup>e</sup>

-crucibles excepted, in which he fused his metals: he would sometimes,

-though very seldom, look into an old mouldy book, which lay in

-his laboratory; I think it was titled <i>Agricola de Metallis</i>, the transmuting

-of metals being his chief design, for which purpose antimony<span class="pagenum"><a name="Page_8" id="Page_8">8</a></span>

-was a great ingredient.” “His brick furnaces, <i>pro re nata</i>, he made

-and altered himself without troubling a bricklayer.” “What observations

-he might make with his telescope, I know not, but several of

-his observations about comets and the planets may be found scattered

-here and there in a book intitled <i>The Elements of Astronomy</i>, by Dr.

-David Gregory.”<a name="FNanchor_5" id="FNanchor_5" href="#Footnote_5" class="fnanchor">5</a></p></blockquote>

-

-<h3>NEWTON’S “APPLE-TREE.”</h3>

-

-<p>Curious and manifold as are the trees associated with the

-great names of their planters, or those who have sojourned in

-their shade, the Tree which, by the falling of its fruit, suggested

-to Newton the idea of Gravity, is of paramount interest.

-It appears that, in the autumn of 1665, Newton left his college

-at Cambridge for his paternal home at Woolsthorpe. “When

-sitting alone in the garden,” says Sir David Brewster, “and

-speculating on the power of gravity, it occurred to him, that as

-the same power by which the apple fell to the ground was not

-sensibly diminished at the greatest distance from the centre of

-the earth to which we can reach, neither at the summits of

-the loftiest spires, nor on the tops of the highest mountains,

-it might extend to the moon and retain her in her orbit, in

-the same manner as it bends into a curve a stone or a cannon-ball

-when projected in a straight line from the surface of the

-earth.”&mdash;<i>Life of Newton</i>, vol. i. p. 26. Sir David Brewster

-notes, that neither Pemberton nor Whiston, who received from

-Newton himself his first ideas of gravity, records this story of

-the falling apple. It was mentioned, however, to Voltaire by

-Catherine Barton, Newton’s niece; and to Mr. Green by Martin

-Folkes, President of the Royal Society. Sir David Brewster

-saw the reputed apple-tree in 1814, and brought away a portion

-of one of its roots. The tree was so much decayed that it was

-cut down in 1820, and the wood of it carefully preserved by

-Mr. Turnor, of Stoke Rocheford.</p>

-

-<p><span class="pagenum"><a name="Page_9" id="Page_9">9</a></span></p>

-

-<blockquote>

-

-<p>De Morgan (in <i>Notes and Queries</i>, 2d series, No. 139, p. 169) questions

-whether the fruit was an apple, and maintains that the anecdote

-rests upon very slight authority; more especially as the idea had for

-many years been floating before the minds of physical inquirers; although

-Newton cleared away the confusions and difficulties which prevented

-very able men from proceeding beyond conjecture, and by this

-means established <i>universal</i> gravitation.</p></blockquote>

-

-<h3>NEWTON’S “PRINCIPIA.”</h3>

-

-<p>“It may be justly said,” observes Halley, “that so many

-and so valuable philosophical truths as are herein discovered

-and put past dispute were never yet owing to the capacity and

-industry of any one man.” “The importance and generality

-of the discoveries,” says Laplace, “and the immense number

-of original and profound views, which have been the germ of

-the most brilliant theories of the philosophers of this (18th)

-century, and all presented with much elegance, will ensure to

-the work on the <i>Mathematical Principles of Natural Philosophy</i>

-a preëminence above all the other productions of human

-genius.”</p>

-

-<h3>DESCARTES’ LABOURS IN PHYSICS.</h3>

-

-<p>The most profound among the many eminent thinkers

-France has produced, is Réné Descartes, of whom the least

-that can be said is, that he effected a revolution more decisive

-than has ever been brought about by any other single mind;

-that he was the first who successfully applied algebra to geometry;

-that he pointed out the important law of the sines;

-that in an age in which optical instruments were extremely

-imperfect, he discovered the changes to which light is subjected

-in the eye by the crystalline lens; that he directed attention

-to the consequences resulting from the weight of the

-atmosphere; and that he moreover detected the causes of the

-rainbow. At the same time, and as if to combine the most

-varied forms of excellence, he is not only allowed to be the first

-geometrician of the age, but by the clearness and admirable

-precision of his style, he became one of the founders of French

-prose. And, although he was constantly engaged in those lofty

-inquiries into the nature of the human mind, which can never

-be studied without wonder, he combined with them a long

-course of laborious experiment upon the animal frame, which

-raised him to the highest rank among the anatomists of his

-time. The great discovery made by Harvey of the Circulation

-of the Blood was neglected by most of his contemporaries; but

-it was at once recognised by Descartes, who made it the basis

-of the physiological part of his work on man. He was likewise

-the discoverer of the lacteals by Aselli, which, like every great<span class="pagenum"><a name="Page_10" id="Page_10">10</a></span>

-truth yet laid before the world, was at its first appearance, not

-only disbelieved, but covered with ridicule.&mdash;<i>Buckle’s History

-of Civilization</i>, vol. i.</p>

-

-<h3>CONIC SECTIONS.</h3>

-

-<p>If a cone or sugar-loaf be cut through in certain directions,

-we shall obtain figures which are termed conic sections: thus,

-if we cut through a sugar-loaf parallel to its base or bottom,

-the outline or edge of the loaf where it is cut will be <i>a circle</i>.

-If the cut is made so as to slant, and not be parallel to the base

-of the loaf, the outline is an <i>ellipse</i>, provided the cut goes quite

-through the sides of the loaf all round; but if it goes slanting,

-and parallel to the line of the loaf’s side, the outline is a <i>parabola</i>,

-a conic section or curve, which is distinguished by characteristic

-properties, every point of it bearing a certain fixed relation

-to a certain point within it, as the circle does to its centre.&mdash;<i>Dr.

-Paris’s Notes to Philosophy in Sport, &amp;c.</i></p>

-

-<h3>POWER OF COMPUTATION.</h3>

-

-<p>The higher class of mathematicians, at the end of the seventeenth

-century, had become excellent computers, particularly

-in England, of which Wallis, Newton, Halley, the Gregorys, and

-De Moivre, are splendid examples. Before results of extreme

-exactness had become quite familiar, there was a gratifying

-sense of power in bringing out the new methods. Newton, in

-one of his letters to Oldenburg, says that he was at one time too

-much attached to such things, and that he should be ashamed

-to say to what number of figures he was in the habit of carrying

-his results. The growth of power of computation on the Continent

-did not, however, keep pace with that of the same in England.

-In 1696, De Laguy, a well-known writer on algebra, and

-a member of the Academy of Sciences, said that the most skilful

-computer could not, in less than a month, find within a unit

-the cube root of 696536483318640035073641037.&mdash;<i>De Morgan.</i></p>

-

-<h3>“THE SCIENCE OF THE COSMOS.”</h3>

-

-<p>Humboldt, characterises this “uncommon but definite expression”

-as the treating of “the assemblage of all things with

-which space is filled, from the remotest nebulæ to the climatic

-distribution of those delicate tissues of vegetable matter which

-spread a variegated covering over the surface of our rocks.”

-The word <i>cosmos</i>, which primitively, in the Homeric ages,

-indicated an idea of order and harmony, was subsequently

-adopted in scientific language, where it was gradually applied

-to the order observed in the movements of the heavenly bodies;

-to the whole universe; and then finally to the world in which

-this harmony was reflected to us.</p>

-

-<hr />

-

-<p><span class="pagenum"><a name="Page_11" id="Page_11">11</a></span></p>

-

-<div class="chapter"></div>

-<h2><a name="Physical" id="Physical"></a>Physical Phenomena.</h2>

-

-<h3>ALL THE WORLD IN MOTION.</h3>

-

-<p>Humboldt, in his <i>Cosmos</i>,<a name="FNanchor_6" id="FNanchor_6" href="#Footnote_6" class="fnanchor">6</a> gives the following beautiful illustrative

-proofs of this phenomenon:</p>

-

-<blockquote>

-

-<p>If, for a moment, we imagine the acuteness of our senses preternaturally

-heightened to the extreme limits of telescopic vision, and bring

-together events separated by wide intervals of time, the apparent repose

-which reigns in space will suddenly vanish; countless stars will be

-seen moving in groups in various directions; nebulæ wandering, condensing,

-and dissolving like cosmical clouds; the milky way breaking

-up in parts, and its veil rent asunder. In every point of the celestial

-vault we shall recognise the dominion of progressive movement, as on

-the surface of the earth where vegetation is constantly putting forth its

-leaves and buds, and unfolding its blossoms. The celebrated Spanish

-botanist, Cavanilles, first conceived the possibility of “seeing grass

-grow,” by placing the horizontal micrometer wire of a telescope, with a

-high magnifying power, at one time on the point of a bamboo shoot, and

-at another on the rapidly unfolding flowering stem of an American aloe;

-precisely as the astronomer places the cross of wires on a culminating

-star. Throughout the whole life of physical nature&mdash;in the organic as

-in the sidereal world&mdash;existence, preservation, production, and development,

-are alike associated with motion as their essential condition.</p></blockquote>

-

-<h3>THE AXIS OF ROTATION.</h3>

-

-<p>It is remarkable as a mechanical fact, that nothing is so permanent

-in nature as the Axis of Rotation of any thing which is

-rapidly whirled. We have examples of this in every-day practice.

-The first is the motion of <i>a boy’s hoop</i>. What keeps the

-hoop from falling?&mdash;It is its rotation, which is one of the most

-complicated subjects in mechanics.</p>

-

-<p>Another thing pertinent to this question is, <i>the motion of a

-quoit</i>. Every body who ever threw a quoit knows that to make

-it preserve its position as it goes through the air, it is necessary

-to give it a whirling motion. It will be seen that while whirling,

-it preserves its plane, whatever the position of the plane

-may be, and however it may be inclined to the direction in

-which the quoit travels. Now, this has greater analogy with

-the motion of the earth than any thing else.</p>

-

-<p>Another illustration is <i>the motion of a spinning top</i>. The

-greatest mathematician of the last century, the celebrated

-Euler, has written a whole book on the motion of a top, and

-his Latin treatise <i>De motu Turbinis</i> is one of the most remarkable

-books on mechanics. The motion of a top is a matter of<span class="pagenum"><a name="Page_12" id="Page_12">12</a></span>

-the greatest importance; it is applicable to the elucidation of

-some of the greatest phenomena of nature. In all these instances

-there is this wonderful tendency in rotation to preserve

-the axis of rotation unaltered.&mdash;<i>Prof. Airy’s Lect. on Astronomy.</i></p>

-

-<h3>THE EARTH’S ANNUAL MOTION.</h3>

-

-<p>In conformity with the Copernican view of our system, we

-must learn to look upon the sun as the comparatively motionless

-centre about which the earth performs an annual elliptic

-orbit of the dimensions and excentricity, and with a velocity,

-regulated according to a certain assigned law; the sun occupying

-one of the foci of the ellipse, and from that station quietly

-disseminating on all sides its light and heat; while the earth

-travelling round it, and presenting itself differently to it at different

-times of the year and day, passes through the varieties of

-day and night, summer and winter, which we enjoy.&mdash;<i>Sir John

-Herschel’s Outlines of Astronomy.</i></p>

-

-<p>Laplace has shown that the length of the day has not varied

-the hundredth part of a second since the observations of Hipparchus,

-2000 years ago.</p>

-

-<h3>STABILITY OF THE OCEAN.</h3>

-

-<p>In submitting this question to analysis, Laplace found that

-the <i>equilibrium of the ocean is stable if its density is less than the

-mean density of the earth</i>, and that its equilibrium cannot be subverted

-unless these two densities are equal, or that of the earth

-less than that of its waters. The experiments on the attraction

-of Schehallien and Mont Cenis, and those made by Cavendish,

-Reich, and Baily, with balls of lead, demonstrate that the mean

-density of the earth is at least <i>five</i> times that of water, and hence

-the stability of the ocean is placed beyond a doubt. As the seas,

-therefore, have at one time covered continents which are now

-raised above their level, we must seek for some other cause of

-it than any want of stability in the equilibrium of the ocean.

-How beautifully does this conclusion illustrate the language of

-Scripture, “Hitherto shalt thou come, but no further”! (<i>Job</i>

-xxxviii. 11.)</p>

-

-<h3>COMPRESSION OF BODIES.</h3>

-

-<p>Sir John Leslie observes, that <i>air compressed</i> into the fiftieth

-part of its volume has its elasticity fifty times augmented: if it

-continued to contract at that rate, it would, from its own incumbent

-weight, acquire the density of water at the depth of

-thirty-four miles. But water itself would have its density

-doubled at the depth of ninety-three miles, and would attain the

-density of quicksilver at the depth of 362 miles. In descending,

-therefore, towards the centre, through nearly 4000 miles, the

-condensation of ordinary substances would surpass the utmost<span class="pagenum"><a name="Page_13" id="Page_13">13</a></span>

-powers of conception. Dr. Young says, that steel would be

-compressed into one-fourth, and stone into one-eighth, of its

-bulk at the earth’s centre.&mdash;<i>Mrs. Somerville.</i></p>

-

-<h3>THE WORLD IN A NUTSHELL.</h3>

-

-<p>From the many proofs of the non-contact of the atoms, even

-in the most solid parts of bodies; from the very great space

-obviously occupied by pores&mdash;the mass having often no more

-solidity than a heap of empty boxes, of which the apparently

-solid parts may still be as porous in a second degree and so on;

-and from the great readiness with which light passes in all directions

-through dense bodies, like glass, rock-crystal, diamond,

-&amp;c., it has been argued that there is so exceedingly little of

-really solid matter even in the densest mass, that <i>the whole

-world</i>, if the atoms could be brought into absolute contact,

-<i>might be compressed into a nutshell</i>. We have as yet no means

-of determining exactly what relation this idea has to truth.&mdash;<i>Arnott.</i></p>

-

-<h3>THE WORLD OF ATOMS.</h3>

-

-<p>The infinite groups of atoms flying through all time and

-space, in different directions and under different laws, have

-interchangeably tried and exhibited every possible mode of rencounter:

-sometimes repelled from each other by concussion;

-and sometimes adhering to each other from their own jagged

-or pointed construction, or from the casual interstices which

-two or more connected atoms must produce, and which may be

-just adapted to those of other figures,&mdash;as globular, oval, or

-square. Hence the origin of compound and visible bodies;

-hence the origin of large masses of matter; hence, eventually,

-the origin of the world.&mdash;<i>Dr. Good’s Book of Nature.</i></p>

-

-<p>The great Epicurus speculated on “the plastic nature” of

-atoms, and attributed to this <i>nature</i> the power they possess of

-arranging themselves into symmetric forms. Modern philosophers

-satisfy themselves with attraction; and reasoning from

-analogy, imagine that each atom has a polar system.&mdash;<i>Hunt’s

-Poetry of Science.</i></p>

-

-<h3>MINUTE ATOMS OF THE ELEMENTS: DIVISIBILITY OF MATTER.</h3>

-

-<p>So minute are the parts of the elementary bodies in their

-ultimate state of division, in which condition they are usually

-termed <i>atoms</i>, as to elude all our powers of inspection, even

-when aided by the most powerful microscopes. Who can see the

-particles of gold in a solution of that metal in <i>aqua regia</i>, or

-those of common salt when dissolved in water? Dr. Thomas

-Thomson has estimated the bulk of an ultimate particle or

-atom of lead as less than 1/888492000000000th of a cubic inch,<span class="pagenum"><a name="Page_14" id="Page_14">14</a></span>

-and concludes that its weight cannot exceed the 1/310000000000th

-of a grain.</p>

-

-<p>This curious calculation was made by Dr. Thomson, in order

-to show to what degree Matter could be divided, and still

-be sensible to the eye. He dissolved a grain of nitrate of lead

-in 500,000 grains of water, and passed through the solution

-a current of sulphuretted hydrogen; when the whole liquid

-became sensibly discoloured. Now, a grain of water may

-be regarded as being almost equal to a drop of that liquid,

-and a drop may be easily spread out so as to cover a square

-inch of surface. But under an ordinary microscope the millionth

-of a square inch may be distinguished by the eye. The

-water, therefore, could be divided into 500,000,000,000 parts.

-But the lead in a grain of nitrate of lead weighs 0·62 of a

-grain; an atom of lead, accordingly, cannot weigh more than

-1/810000000000th of a grain; while the atom of sulphur,

-which in combination with the lead rendered it visible, could

-not weigh more than 1/2015000000000, that is, the two-billionth

-part of a grain.&mdash;<i>Professor Low</i>; <i>Jameson’s Journal</i>, No. 106.</p>

-

-<h3>WEIGHT OF AIR.</h3>

-

-<p>Air can be so rarefied that the contents of a cubic foot shall

-not weigh the tenth part of a grain: if a quantity that would

-fill a space the hundredth part of an inch in diameter be separated

-from the rest, the air will still be found there, and we

-may reasonably conceive that there may be several particles

-present, though the weight is less than the seventeen-hundred-millionth

-of a grain.</p>

-

-<h3>DURATION OF THE PYRAMID.</h3>

-

-<p>The great reason of the duration of the pyramid above all

-other forms is, that it is most fitted to resist the force of gravitation.

-Thus the Pyramids of Egypt are the oldest monuments

-in the world.</p>

-

-<h3>INERTIA ILLUSTRATED.</h3>

-

-<p>Many things of common occurrence (says Professor Tyndall)

-are to be explained by reference to the quality of inactivity.

-We will here state a few of them.</p>

-

-<p>When a railway train is moving, if it strike against any obstacle

-which arrests its motion, the passengers are thrown

-forward in the direction in which the train was proceeding.

-Such accidents often occur on a small scale, in attaching carriages

-at railway stations. The reason is, that the passengers

-share the motion of the train, and, as matter, they tend to

-persist in motion. When the train is suddenly checked, this

-tendency exhibits itself by the falling forward referred to. In<span class="pagenum"><a name="Page_15" id="Page_15">15</a></span>

-like manner, when a train previously at rest is suddenly set in

-motion, the tendency of the passengers to remain at rest evinces

-itself by their falling in a direction opposed to that in which

-the train moves.</p>

-

-<h3>THE LEANING TOWER OF PISA.<a name="FNanchor_7" id="FNanchor_7" href="#Footnote_7" class="fnanchor">7</a></h3>

-

-<p>Sir John Leslie used to attribute the stability of this tower

-to the cohesion of the mortar it is built with being sufficient to

-maintain it erect, in spite of its being out of the condition required

-by physics&mdash;to wit, that “in order that a column shall

-stand, a perpendicular let fall from the centre of gravity must

-fall within the base.” Sir John describes the Tower of Pisa to

-be in violation of this principle; but, according to later authorities,

-the perpendicular falls within the base.</p>

-

-<h3>EARLY PRESENTIMENTS OF CENTRIFUGAL FORCES.</h3>

-

-<p>Jacobi, in his researches on the mathematical knowledge of

-the Greeks, comments on “the profound consideration of nature

-evinced by Anaxagoras, in whom we read with astonishment a

-passage asserting that the moon, if the centrifugal force were

-intermitted, would fall to the earth like a stone from a sling.”

-Anaxagoras likewise applied the same theory of “falling where

-the force of rotation had been intermitted” to all the material

-celestial bodies. In Aristotle and Simplicius may also be

-traced the idea of “the non-falling of heavenly bodies when

-the rotatory force predominates over the actual falling force,

-or downward attraction;” and Simplicius mentions that “water

-in a phial is not spilt when the movement of rotation is

-more rapid than the downward movement of the water.” This

-is illustrated at the present day by rapidly whirling a pail half-filled

-with water without spilling a drop.</p>

-

-<p>Plato had a clearer idea than Aristotle of the <i>attractive force</i>

-exercised by the earth’s centre on all heavy bodies removed

-from it; for he was acquainted with the acceleration of falling<span class="pagenum"><a name="Page_16" id="Page_16">16</a></span>

-bodies, although he did not correctly understand the cause.

-John Philoponus, the Alexandrian, probably in the sixth century,

-was the first who ascribed the movement of the heavenly

-bodies to a primitive impulse, connecting with this idea that

-of the fall of bodies, or the tendency of all substances, whether

-heavy or light, to reach the ground. The idea conceived by

-Copernicus, and more clearly expressed by Kepler, who even

-applied it to the ebb and flow of the ocean, received in 1666

-and 1674 a new impulse from Robert Hooke; and next Newton’s

-theory of gravitation presented the grand means of converting

-the whole of physical astronomy into a true <i>mechanism

-of the heavens</i>.</p>

-

-<p>The law of gravitation knows no exception; it accounts accurately

-for the most complex motions of the members of our

-own system; nay more, the paths of double stars, far removed

-from all appreciable effects of our portion of the universe, are

-in perfect accordance with its theory.<a name="FNanchor_8" id="FNanchor_8" href="#Footnote_8" class="fnanchor">8</a></p>

-

-<h3>HEIGHT OF FALLS.</h3>

-

-<p>The fancy of the Greeks delighted itself in wild visions of the

-height of falls. In Hesiod’s <i>Theogony</i> it is said, speaking of the

-fall of the Titans into Tartarus, “if a brazen anvil were to fall

-from heaven nine days and nine nights long, it would reach

-the earth on the tenth.” This descent of the anvil in 777,600

-seconds of time gives an equivalent in distance of 309,424 geographical

-miles (allowance being made, according to Galle’s

-calculation, for the considerable diminution in force of attraction

-at planetary distances); therefore 1½ times the distance

-of the moon from the earth. But, according to the <i>Iliad</i>, Hephæstus

-fell down to Lemnos in one day; “when but a little

-breath was still in him.”&mdash;<i>Note to Humboldt’s Cosmos</i>, vol. iii.</p>

-

-<h3>RATE OF THE FALL OF BODIES.</h3>

-

-<p>A body falls in gravity precisely 16-1/16 feet in a second, and

-the velocity increases according to the squares of the time, viz.:</p>

-

-<table summary="Rate of the fall of bodies">

-  <tr>

-    <td class="tdl">In ¼ (quarter of a second) a body falls</td>

-    <td class="tdr">1</td>

-    <td class="tdc">foot.</td></tr>

-  <tr>

-    <td class="tdl int16">½ (half a second)</td>

-    <td class="tdr">4</td>

-    <td class="tdc">feet.</td></tr>

-  <tr>

-    <td class="tdl int16">1 second</td>

-    <td class="tdr">16</td>

-    <td class="tdc">”</td></tr>

-  <tr>

-    <td class="tdl int16">2 ditto</td>

-    <td class="tdr">64</td>

-    <td class="tdc">”</td></tr>

-  <tr>

-    <td class="tdl int16">3 ditto</td>

-    <td class="tdr">144</td>

-    <td class="tdc">”</td></tr>

-</table>

-

-<p><span class="pagenum"><a name="Page_17" id="Page_17">17</a></span>

-The power of gravity at two miles distance from the earth is

-four times less than at one mile; at three miles nine times

-less, and so on. It goes on lessening, but is never destroyed.&mdash;<i>Notes

-in various Sciences.</i></p>

-

-<h3>VARIETIES OF SPEED.</h3>

-

-<p>A French scientific work states the ordinary rate to be:</p>

-

-<table summary="Varieties of speed">

-  <tr class="smaller">

-    <td> </td>

-    <td class="tdc" colspan="2">per second.</td></tr>

-  <tr>

-    <td class="tdl">Of a man walking</td>

-    <td class="tdr">4</td>

-    <td class="tdc">feet.</td></tr>

-  <tr>

-    <td class="tdl">Of a good horse in harness</td>

-    <td class="tdr">12</td>

-    <td class="tdc">”</td></tr>

-  <tr>

-    <td class="tdl">Of a rein-deer in a sledge on the ice</td>

-    <td class="tdr">26</td>

-    <td class="tdc">”</td></tr>

-  <tr>

-    <td class="tdl">Of an English race-horse</td>

-    <td class="tdr">43</td>

-    <td class="tdc">”</td></tr>

-  <tr>

-    <td class="tdl">Of a hare</td>

-    <td class="tdr">88</td>

-    <td class="tdc">”</td></tr>

-  <tr>

-    <td class="tdl">Of a good sailing ship</td>

-    <td class="tdr">19</td>

-    <td class="tdc">”</td></tr>

-  <tr>

-    <td class="tdl">Of the wind</td>

-    <td class="tdr">82</td>

-    <td class="tdc">”</td></tr>

-  <tr>

-    <td class="tdl">Of sound</td>

-    <td class="tdr">1038</td>

-    <td class="tdc">”</td></tr>

-  <tr>

-    <td class="tdl">Of a 24-pounder cannon-ball</td>

-    <td class="tdr">1300</td>

-    <td class="tdc">”</td></tr>

-</table>

-

-<h3>LIFTING HEAVY PERSONS.</h3>

-

-<p>One of the most extraordinary pages in Sir David Brewster’s

-<i>Letters on Natural Magic</i> is the experiment in which a heavy

-man is raised with the greatest facility when he is lifted up the

-instant that his own lungs, and those of the persons who raise

-him, are inflated with air. Thus the heaviest person in the

-party lies down upon two chairs, his legs being supported by

-the one and his back by the other. Four persons, one at each

-leg, and one at each shoulder, then try to raise him&mdash;the person

-to be raised giving two signals, by clapping his hands. At

-the first signal, he himself and the four lifters begin to draw a

-long and full breath; and when the inhalation is completed, or

-the lungs filled, the second signal is given for raising the person

-from the chair. To his own surprise, and that of his bearers,

-he rises with the greatest facility, as if he were no heavier than

-a feather. Sir David Brewster states that he has seen this

-inexplicable experiment performed more than once; and he

-appealed for testimony to Sir Walter Scott, who had repeatedly

-seen the experiment, and performed the part both of the load

-and of the bearer. It was first shown in England by Major H.,

-who saw it performed in a large party at Venice, under the direction

-of an officer of the American navy.<a name="FNanchor_9" id="FNanchor_9" href="#Footnote_9" class="fnanchor">9</a></p>

-

-<p>Sir David Brewster (in a letter to <i>Notes and Queries</i>, No. 143)

-further remarks, that “the inhalation of the lifters the moment

-the effort is made is doubtless essential, and for this reason:

-when we make a great effort, either in pulling or lifting, we

-always fill the chest with air previous to the effort; and when<span class="pagenum"><a name="Page_18" id="Page_18">18</a></span>

-the inhalation is completed, we close the <i>rima glottidis</i> to keep

-the air in the lungs. The chest being thus kept expanded, the

-pulling or lifting muscles have received as it were a fulcrum

-round which their power is exerted; and we can thus lift the

-greatest weight which the muscles are capable of doing. When

-the chest collapses by the escape of the air, the lifters lose their

-muscular power; reinhalation of air by the liftee can certainly

-add nothing to the power of the lifters, or diminish his own

-weight, which is only increased by the weight of the air which

-he inhales.”</p>

-

-<h3>“FORCE CAN NEITHER BE CREATED NOR DESTROYED.”</h3>

-

-<p>Professor Faraday, in his able inquiry upon “the Conservation

-of Force,” maintains that to admit that force may be destructible,

-or can altogether disappear, would be to admit that

-matter could be uncreated; for we know matter only by its

-forces. From his many illustrations we select the following:</p>

-

-<blockquote>

-

-<p>The indestructibility of individual matter is a most important case of

-the Conservation of Chemical Force. A molecule has been endowed with

-powers which give rise in it to various qualities; and those never change,

-either in their nature or amount. A particle of oxygen is ever a particle

-of oxygen; nothing can in the least wear it. If it enters into combination,

-and disappears as oxygen; if it pass through a thousand combinations&mdash;animal,

-vegetable, mineral; if it lie hid for a thousand years, and

-then be evolved,&mdash;it is oxygen with the first qualities, neither more nor

-less. It has all its original force, and only that; the amount of force

-which it disengaged when hiding itself, has again to be employed in a

-reverse direction when it is set at liberty: and if, hereafter, we should

-decompose oxygen, and find it compounded of other particles, we should

-only increase the strength of the proof of the conservation of force; for

-we should have a right to say of these particles, long as they have been

-hidden, all that we could say of the oxygen itself.</p></blockquote>

-

-<p>In conclusion, he adds:</p>

-

-<blockquote>

-

-<p>Let us not admit the destruction or creation of force without clear

-and constant proof. Just as the chemist owes all the perfection of his

-science to his dependence on the certainty of gravitation applied by the

-balance, so may the physical philosopher expect to find the greatest

-security and the utmost aid in the principle of the conservation of force.

-All that we have that is good and safe&mdash;as the steam-engine, the electric

-telegraph, &amp;c.&mdash;witness to that principle; it would require a perpetual

-motion, a fire without heat, heat without a source, action without reaction,

-cause without effect, or effect without cause, to displace it from

-its rank as a law of nature.</p></blockquote>

-

-<h3>NOTHING LOST IN THE MATERIAL WORLD.</h3>

-

-<p>“It is remarkable,” says Kobell in his <i>Mineral Kingdom</i>,

-“how a change of place, a circulation as it were, is appointed

-for the inanimate or naturally immovable things upon the earth;

-and how new conditions, new creations, are continually developing

-themselves in this way. I will not enter here into the<span class="pagenum"><a name="Page_19" id="Page_19">19</a></span>

-evaporation of water, for instance from the widely-spreading

-ocean; how the clouds produced by this pass over into foreign

-lands and then fall again to the earth as rain, and how this

-wandering water is, partly at least, carried along new journeys,

-returning after various voyages to its original home: the mere

-mechanical phenomena, such as the transfer of seeds by the

-winds or by birds, or the decomposition of the surface of the

-earth by the friction of the elements, suffice to illustrate this.”</p>

-

-<h3>TIME AN ELEMENT OF FORCE.</h3>

-

-<p>Professor Faraday observes that Time is growing up daily

-into importance as an element in the exercise of Force, which

-he thus strikingly illustrates:</p>

-

-<blockquote>

-

-<p>The earth moves in its orbit of time; the crust of the earth moves in

-time; light moves in time; an electro-magnet requires time for its charge

-by an electric current: to inquire, therefore, whether power, acting either

-at sensible or insensible distances, always acts in <i>time</i>, is not to be metaphysical;

-if it acts in time and across space, it must act by physical

-lines of force; and our view of the nature of force may be affected to

-the extremest degree by the conclusions which experiment and observation

-on time may supply, being perhaps finally determinable only by

-them. To inquire after the possible time in which gravitating, magnetic,

-or electric force is exerted, is no more metaphysical than to mark the

-times of the hands of a clock in their progress; or that of the temple of

-Serapis, and its ascents and descents; or the periods of the occultation

-of Jupiter’s satellites; or that in which the light comes from them to

-the earth. Again, in some of the known cases of the action of time

-something happens while <i>the time</i> is passing which did not happen before,

-and does not continue after; it is therefore not metaphysical to

-expect an effect in <i>every</i> case, or to endeavour to discover its existence

-and determine its nature.</p></blockquote>

-

-<h3>CALCULATION OF HEIGHTS AND DISTANCES.</h3>

-

-<p>By the assistance of a seconds watch the following interesting

-calculations may be made:</p>

-

-<blockquote>

-

-<p>If a traveller, when on a precipice or on the top of a building, wish

-to ascertain the height, he should drop a stone, or any other substance

-sufficiently heavy not to be impeded by the resistance of the atmosphere;

-and the number of seconds which elapse before it reaches the bottom,

-carefully noted on a seconds watch, will give the height. For the stone

-will fall through the space of 16-1/8 feet during the first second, and will

-increase in rapidity as the square of the time employed in the fall: if,

-therefore, 16-1/8 be multiplied by the number of seconds the stone has

-taken to fall, this product also multiplied by the same number of seconds

-will give the height. Suppose the stone takes five seconds to reach the

-bottom:</p>

-

-<p class="center">

-16-1/8 × 5 = 80-5/8 × 5 = 403-1/8, height of the precipice.

-</p>

-

-<p>The Count Xavier de Maistre, in his <i>Expédition nocturne autour de

-ma Chambre</i>, anxious to ascertain the exact height of his room from the

-ground on which Turin is built, tells us he proceeded as follows: “My

-heart beat quickly, and I just counted three pulsations from the instant<span class="pagenum"><a name="Page_20" id="Page_20">20</a></span>

-I dropped my slipper until I heard the sound as it fell in the street,

-which, according to the calculations made of the time taken by bodies

-in their accelerated fall, and of that employed by the sonorous undulations

-of the air to arrive from the street to my ear, gave the height of

-my apartment as 94 feet 3 inches 1 tenth (French measure), supposing

-that my heart, agitated as it was, beat 120 times in a minute.”</p>

-

-<p>A person travelling may ascertain his rate of walking by the aid of a

-slight string with a piece of lead at one end, and the use of a seconds

-watch; the string being knotted at distances of 44 feet, the 120th part

-of an English mile, and bearing the same proportion to a mile that half

-a minute bears to an hour. If the traveller, when going at his usual

-rate, drops the lead, and suffers the string to slip through his hand, the

-number of knots which pass in half a minute indicate the number of

-miles he walks in an hour. This contrivance is similar to a <i>log-line</i> for

-ascertaining a ship’s rate at sea: the lead is enclosed in wood (whence

-the name <i>log</i>), that it may float, and the divisions, which are called

-<i>knots</i>, are measured for nautical miles. Thus, if ten knots are passed in

-half a minute, they show that the vessel is sailing at the rate of ten knots,

-or miles, an hour: a seconds watch would here be of great service, but

-the half-minute sand-glass is in general use.</p>

-

-<p>The rapidity of a river may be ascertained by throwing in a light

-floating substance, which, if not agitated by the wind, will move with

-the same celerity as the water: the distance it floats in a certain number

-of seconds will give the rapidity of the stream; and this indicates the

-height of its source, the nature of its bottom, &amp;c.&mdash;See <i>Sir Howard

-Douglas on Bridges</i>. <i>Thomson’s Time and Time-keepers.</i></p></blockquote>

-

-<h3>SAND IN THE HOUR-GLASS.</h3>

-

-<p>It is a noteworthy fact, that the flow of Sand in the Hour-glass

-is perfectly equable, whatever may be the quantity in the

-glass; that is, the sand runs no faster when the upper half of

-the glass is quite full than when it is nearly empty. It would,

-however, be natural enough to conclude, that when full of sand

-it would be more swiftly urged through the aperture than when

-the glass was only a quarter full, and near the close of the hour.</p>

-

-<p>The fact of the even flow of sand may be proved by a very

-simple experiment. Provide some silver sand, dry it over or

-before the fire, and pass it through a tolerably fine sieve. Then

-take a tube, of any length or diameter, closed at one end, in

-which make a small hole, say the eighth of an inch; stop this

-with a peg, and fill up the tube with the sifted sand. Hold the

-tube steadily, or fix it to a wall or frame at any height from a

-table; remove the peg, and permit the sand to flow in any measure

-for any given time, and note the quantity. Then let the

-tube be emptied, and only half or a quarter filled with sand;

-measure again for a like time, and the same quantity of sand

-will flow: even if you press the sand in the tube with a ruler

-or stick, the flow of the sand through the hole will not be increased.</p>

-

-<p>The above is explained by the fact, that when the sand is

-poured into the tube, it fills it with a succession of conical<span class="pagenum"><a name="Page_21" id="Page_21">21</a></span>

-heaps; and that all the weight which the bottom of the tube

-sustains is only that of the heap which <i>first</i> falls upon it, as

-the succeeding heaps do not press downward, but only against

-the sides or walls of the tube.</p>

-

-<h3>FIGURE OF THE EARTH.</h3>

-

-<p>By means of a purely astronomical determination, based

-upon the action which the earth exerts on the motion of the

-moon, or, in other words, on the inequalities in lunar longitudes

-and latitudes, Laplace has shown in one single result the

-mean Figure of the Earth.</p>

-

-<blockquote>

-

-<p>It is very remarkable that an astronomer, without leaving his observatory,

-may, merely by comparing his observations with mean analytical

-results, not only be enabled to determine with exactness the size and

-degree of ellipticity of the earth, but also its distance from the sun and

-moon; results that otherwise could only be arrived at by long and arduous

-expeditions to the most remote parts of both hemispheres. The

-moon may therefore, by the observation of its movements, render appreciable

-to the higher departments of astronomy the ellipticity of the

-earth, as it taught the early astronomers the rotundity of our earth by

-means of its eclipses.&mdash;<i>Laplace’s Expos. du Syst. du Monde.</i></p></blockquote>

-

-<h3>HOW TO ASCERTAIN THE EARTH’S MAGNITUDE.</h3>

-

-<p>Sir John Herschel gives the following means of approximation.

-It appears by observation that two points, each ten feet

-above the surface, cease to be visible from each other over still

-water, and, in average atmospheric circumstances, at a distance

-of about eight miles. But 10 feet is the 528th part of a mile;

-so that half their distance, or four miles, is to the height of

-each as 4 × 528, or 2112:1, and therefore in the same proportion

-to four miles is the length of the earth’s diameter. It

-must, therefore, be equal to 4 × 2112 = 8448, or in round numbers,

-about 8000 miles, which is not very far from the truth.</p>

-

-<blockquote>

-

-<p>The excess is, however, about 100 miles, or 1/80th part. As convenient

-numbers to remember, the reader may bear in mind, that in our latitude

-there are just as many thousands of feet in a degree of the meridian as

-there are days in the year (365); that, speaking loosely, a degree is

-about seventy British statute miles, and a second about 100 feet; that

-the equatorial circumference of the earth is a little less than 25,000

-miles (24,899), and the ellipticity or polar flattening amounts to 1/300th

-part of the diameter.&mdash;<i>Outlines of Astronomy.</i></p></blockquote>

-

-<h3>MASS AND DENSITY OF THE EARTH.</h3>

-

-<p>With regard to the determination of the Mass and Density

-of the Earth by direct experiment, we have, in addition to the

-deviations of the pendulum produced by mountain masses, the

-variation of the same instruments when placed in a mine 1200

-feet in depth. The most recent experiments were conducted<span class="pagenum"><a name="Page_22" id="Page_22">22</a></span>

-by Professor Airy, in the Harton coal-pit, near South Shields:<a name="FNanchor_10" id="FNanchor_10" href="#Footnote_10" class="fnanchor">10</a>

-the oscillations of the pendulum at the bottom of the pit were

-compared with those of a clock above; the beats of the clock

-were transferred below for comparison by an electrio wire; and

-it was thus determined that a pendulum vibrating seconds at the

-mouth of the pit would gain 2¼ seconds per day at its bottom.

-The final result of the calculations depending on this experiment,

-which were published in the <i>Philosophical Transactions</i> of 1856,

-gives 6·565 for the mean density of the earth. The celebrated

-Cavendish experiment, by means of which the density of the

-earth was determined by observing the attraction of leaden

-balls on each other, has been repeated in a manner exhibiting

-an astonishing amount of skill and patience by the late Mr. F.

-Baily.<a name="FNanchor_11" id="FNanchor_11" href="#Footnote_11" class="fnanchor">11</a> The result of these experiments, combined with those

-previously made, gives as a mean result 5·441 as the earth’s

-density, when compared with water; thus confirming one of

-Newton’s astonishing divinations, that the mean density of the

-earth would be found to be between five and six times that of

-water.</p>

-

-<blockquote>

-

-<p>Humboldt is, however, of opinion that “we know only the mass of

-the whole earth and its mean density by comparing it with the open

-strata, which alone are accessible to us. In the interior of the earth,

-where all knowledge of its chemical and mineralogical character fails,

-we are limited to as pure conjecture as in the remotest bodies that

-revolve round the sun. We can determine nothing with certainty regarding

-the depth at which the geological strata must be supposed to

-be in a state of softening or of liquid fusion, of the condition of fluids

-when heated under an enormous pressure, or of the law of the increase

-of density from the upper surface to the centre of the earth.”&mdash;<i>Cosmos</i>,

-vol. i.</p></blockquote>

-

-<p>In M. Foucault’s beautiful experiment, by means of the

-vibration of a long pendulum, consisting of a heavy mass of

-metal suspended by a long wire from a strong fixed support, is

-demonstrated to the eye the rotation of the earth. The Gyroscope

-of the same philosopher is regarded not as a mere philosophical

-toy; but the principles of dynamics, by means of

-which it is made to demonstrate the earth’s rotation on its own

-axis, are explained with the greatest clearness. Thus the ingenuity

-of M. Foucault, combined with a profound knowledge of

-mechanics, has obtained proofs of one of the most interesting

-problems of astronomy from an unsuspected source.</p>

-

-<h3>THE EARTH AND MAN COMPARED.</h3>

-

-<p>The Earth&mdash;speaking roundly&mdash;is 8000 miles in diameter;<span class="pagenum"><a name="Page_23" id="Page_23">23</a></span>

-the atmosphere is calculated to be fifty miles in altitude; the

-loftiest mountain peak is estimated at five miles above the level

-of the sea, for this height has never been visited by man; the

-deepest mine that he has formed is 1650 feet; and his own

-stature does not average six feet. Therefore, if it were possible

-for him to construct a globe 800 feet&mdash;or twice the height of

-St. Paul’s Cathedral&mdash;in diameter, and to place upon any one

-point of its surface an atom of 1/4380th of an inch in diameter,

-and 1/720th of an inch in height, it would correctly denote the

-proportion that man bears to the earth upon which he moves.</p>

-

-<blockquote>

-

-<p>When by measurements, in which the evidence of the method advances

-equally with the precision of the results, the volume of the earth

-is reduced to the millionth part of the volume of the sun; when the sun

-himself, transported to the region of the stars, takes up a very modest

-place among the thousands of millions of those bodies that the telescope

-has revealed to us; when the 38,000,000 of leagues which separate the

-earth from the sun have become, by reason of their comparative smallness,

-a base totally insufficient for ascertaining the dimensions of the

-visible universe; when even the swiftness of the luminous rays (77,000

-leagues per second) barely suffices for the common valuations of science;

-when, in short, by a chain of irresistible proofs, certain stars have retired

-to distances that light could not traverse in less than a million of

-years;&mdash;we feel as if annihilated by such immensities. In assigning to

-man and to the planet that he inhabits so small a position in the material

-world, astronomy seems really to have made progress only to

-humble us.&mdash;<i>Arago.</i></p></blockquote>

-

-<h3>MEAN TEMPERATURE OF THE EARTH’S SURFACE.</h3>

-

-<p>Professor Dove has shown, by taking at all seasons the

-mean of the temperature of points diametrically opposite to

-each other, that the mean temperature <i>of the whole earth’s surface</i>

-in June considerably exceeds that in December. This result,

-which is at variance with the greater proximity of the

-sun in December, is, however, due to a totally different and

-very powerful cause,&mdash;the greater amount of land in that

-hemisphere which has its summer solstice in June (<i>i. e.</i> the

-northern); and the fact is so explained by him. The effect of

-land under sunshine is to throw heat into the general atmosphere,

-and to distribute it by the carrying power of the latter

-over the whole earth. Water is much less effective in this

-respect, the heat penetrating its depths and being there absorbed;

-so that the surface never acquires a very elevated

-temperature, even under the equator.&mdash;<i>Sir John Herschel’s

-Outlines.</i></p>

-

-<h3>TEMPERATURE OF THE EARTH STATIONARY.</h3>

-

-<p>Although, according to Bessel, 25,000 cubic miles of water

-flow in every six hours from one quarter of the earth to another,

-and the temperature is augmented by the ebb and flow of every<span class="pagenum"><a name="Page_24" id="Page_24">24</a></span>

-tide, all that we know with certainty is, that the <i>resultant

-effect</i> of all the thermal agencies to which the earth is exposed

-has undergone no perceptible change within the historic period.

-We owe this fine deduction to Arago. In order that the <i>date

-palm</i> should ripen its fruit, the mean temperature of the place

-must exceed 70 deg. Fahr.; and, on the other hand, the <i>vine</i>

-cannot be cultivated successfully when the temperature is

-72 deg. or upwards. Hence the mean temperature of any

-place at which these two plants flourished and bore fruit must

-lie between these narrow limits, <i>i. e.</i> could not differ from

-71 deg. Fahr. by more than a single degree. Now from the

-Bible we learn that both plants were <i>simultaneously</i> cultivated

-in the central valleys of Palestine in the time of Moses; and

-its then temperature is thus definitively determined. It is the

-same at the present time; so that the mean temperature of

-this portion of the globe has not sensibly altered in the course

-of thirty-three centuries.</p>

-

-<h3>THEORY OF CRYSTALLISATION.</h3>

-

-<p>Professor Plücker has ascertained that certain crystals, in

-particular the cyanite, “point very well to the north by the

-magnetic power of the earth only. It is a true compass-needle;

-and more than that, you may obtain its declination.” Upon

-this Mr. Hunt remarks: “We must remember that this crystal,

-the cyanite, is a compound of silica and alumina only. This

-is the amount of experimental evidence which science has

-afforded in explanation of the conditions under which nature

-pursues her wondrous work of crystal formation. We see just

-sufficient of the operation to be convinced that the luminous

-star which shines in the brightness of heaven, and the cavern-secreted

-gem, are equally the result of forces which are known

-to us in only a few of their modifications.”&mdash;<i>Poetry of Science.</i></p>

-

-<p>Gay Lussac first made the remark, that a crystal of potash-alum,

-transferred to a solution of ammonia-alum, continued to

-increase without its form being modified, and might thus be

-covered with alternate layers of the two alums, preserving its

-regularity and proper crystalline figure. M. Beudant afterwards

-observed that other bodies, such as the sulphates of iron

-and copper, might present themselves in crystals of the same

-form and angles, although the form was not a simple one, like

-that of alum. But M. Mitscherlich first recognised this correspondence

-in a sufficient number of cases to prove that it was

-a general consequence of similarity of composition in different

-bodies.&mdash;<i>Graham’s Elements of Chemistry.</i></p>

-

-<h3>IMMENSE CRYSTALS.</h3>

-

-<p>Crystals are found in the most microscopic character, and<span class="pagenum"><a name="Page_25" id="Page_25">25</a></span>

-of an exceedingly large size. A crystal of quartz at Milan is

-three feet and a quarter long, and five feet and a half in circumference:

-its weight is 870 pounds. Beryls have been found

-in New Hampshire measuring four feet in length.&mdash;<i>Dana.</i></p>

-

-<h3>VISIBLE CRYSTALLISATION.</h3>

-

-<p>Professor Tyndall, in a lecture delivered by him at the Royal

-Institution, London, on the properties of Ice, gave the following

-interesting illustration of crystalline force. By perfectly cleaning

-a piece of glass, and placing on it a film of a solution of chloride

-of ammonium or sal ammoniac, the action of crystallisation

-was shown to the whole audience. The glass slide was placed

-in a microscope, and the electric light passing through it was

-concentrated on a white disc. The image of the crystals, as

-they started into existence, and shot across the disc in exquisite

-arborescent and symmetrical forms, excited the admiration

-of every one. The lecturer explained that the heat, causing

-the film of moisture to evaporate, brought the particles of salt

-sufficiently near to exercise the crystalline force, the result

-being the beautiful structure built up with such marvellous

-rapidity.</p>

-

-<h3>UNION OF MINERALOGY AND GEOMETRY.</h3>

-

-<p>It is a peculiar characteristic of minerals, that while plants

-and animals differ in various regions of the earth, mineral matter

-of the same character may be discovered in any part of the world,&mdash;at

-the Equator or towards the Poles; at the summit of the

-loftiest mountains, and in works far beneath the level of the

-sea. The granite of Australia does not necessarily differ from

-that of the British islands; and ores of the same metals (the

-proper geological conditions prevailing) may be found of the

-same general character in all regions. Climate and geographical

-position have no influence on the composition of mineral

-substances.</p>

-

-<p>This uniformity may, in some measure, have induced philosophers

-to seek its extension to the forms of crystallography.

-About 1760 (says Mr. Buckle, in his <i>History of Civilization</i>),

-Romé de Lisle set the first example of studying crystals, according

-to a scheme so large as to include all the varieties of

-their primary forms, and to account for their irregularities and

-the apparent caprice with which they were arranged. In this

-investigation he was guided by the fundamental assumption,

-that what is called an irregularity is in truth perfectly regular,

-and that the operations of nature are invariable. Haüy applied

-this great idea to the almost innumerable forms in which

-minerals crystallise. He thus achieved a complete union between

-mineralogy and geometry; and, bringing the laws of space<span class="pagenum"><a name="Page_26" id="Page_26">26</a></span>

-to bear on the molecular arrangements of matter, he was able

-to penetrate into the intimate structure of crystals. By this

-means he proved that the secondary forms of all crystals are derived

-from their primary forms by a regular process of decrement;

-and that when a substance is passing from a liquid to a solid

-state, its particles cohere, according to a scheme which provides

-for every possible change, since it includes even those subsequent

-layers which alter the ordinary type of the crystal, by

-disturbing its natural symmetry. To ascertain that such violations

-of symmetry are susceptible of mathematical calculation,

-was to make a vast addition to our knowledge; and, by proving

-that even the most uncouth and singular forms are the natural

-results of their antecedents, Haüy laid the foundation of what

-may be called the pathology of the inorganic world. However

-paradoxical such a notion may appear, it is certain that symmetry

-is to crystals what health is to animals; so that an irregularity

-of shape in the first corresponds with an appearance of

-disease in the second.&mdash;See <i>Hist. Civilization</i>, vol. i.</p>

-

-<h3>REPRODUCTIVE CRYSTALLISATION.</h3>

-

-<p>The general belief that only organic beings have the power

-of reproducing lost parts has been disproved by the experiments

-of Jordan on crystals. An octohedral crystal of alum was fractured;

-it was then replaced in a solution, and after a few days

-its injury was seen to be repaired. The whole crystal had of

-course increased in size; but the increase on the broken surface

-had been so much greater that a perfect octohedral form was

-regained.&mdash;<i>G.&nbsp;H. Lewes.</i></p>

-

-<p>This remarkable power possessed by crystals, in common

-with animals, of repairing their own injuries had, however,

-been thus previously referred to by Paget, in his <i>Pathology</i>,

-confirming the experiments of Jordan on this curious subject:

-“The ability to repair the damages sustained by injury ... is

-not an exclusive property of living beings; for even crystals

-will repair themselves when, after pieces have been broken from

-them, they are placed in the same conditions in which they

-were first formed.”</p>

-

-<h3>GLASS BROKEN BY SAND.</h3>

-

-<p>In some glass-houses the workmen show glass which has

-been cooled in the open air; on this they let fall leaden bullets

-without breaking the glass. They afterwards desire you

-to let a few grains of sand fall upon the glass, by which it is

-broken into a thousand pieces. The reason of this is, that the

-lead does not scratch the surface of the glass; whereas the sand,

-being sharp and angular, scratches it sufficiently to produce

-the above effect.</p>

-

-<hr />

-

-<p><span class="pagenum"><a name="Page_27" id="Page_27">27</a></span></p>

-

-<div class="chapter"></div>

-<h2><a name="Sound" id="Sound"></a>Sound and Light.</h2>

-

-<h3>SOUNDING SAND.</h3>

-

-<p>Mr. Hugh Miller, the geologist, when in the island of Eigg,

-in the Hebrides, observed that a musical sound was produced

-when he walked over the white dry sand of the beach. At each

-step the sand was driven from his footprint, and the noise was

-simultaneous with the scattering of the sand; the cause being

-either the accumulated vibrations of the air when struck by

-the driven sand, or the accumulated sounds occasioned by the

-mutual impact of the particles of sand against each other. If

-a musket-ball passing through the air emits a whistling note,

-each individual particle of sand must do the same, however

-faint be the note which it yields; and the accumulation of

-these infinitesimal vibrations must constitute an audible sound,

-varying with the number and velocity of the moving particles.

-In like manner, if two plates of silex or quartz, which are but

-crystals of sand, give out a musical sound when mutually

-struck, the impact or collision of two minute crystals or particles

-of sand must do the same, in however inferior a degree;

-and the union of all these sounds, though singly imperceptible,

-may constitute the musical notes of “the Mountain of the

-Bell” in Arabia Petræa, or the lesser sounds of the trodden

-sea-beach of Eigg.&mdash;<i>North-British Review</i>, No. 5.</p>

-

-<h3>INTENSITY OF SOUND IN RAREFIED AIR.</h3>

-

-<p>The experiences during ascents of the highest mountains

-are contradictory. Saussure describes the sounds on the top

-of Mont Blanc as remarkably weak: a pistol-shot made no

-more noise than an ordinary Chinese cracker, and the popping

-of a bottle of champagne was scarcely audible. Yet Martius,

-in the same situation, was able to distinguish the voices of the

-guides at a distance of 1340 feet, and to hear the tapping of a

-lead pencil upon a metallic surface at a distance of from 75 to

-100 feet.</p>

-

-<p>MM Wertheim and Breguet have propagated sound over

-the wire of an electric telegraph at the rate of 11,454 feet per

-second.</p>

-

-<h3>DISTANCE AT WHICH THE HUMAN VOICE MAY BE HEARD.</h3>

-

-<p>Experience shows that the human voice, under favourable

-circumstances, is capable of filling a larger space than was ever<span class="pagenum"><a name="Page_28" id="Page_28">28</a></span>

-probably enclosed within the walls of a single room. Lieutenant

-Foster, on Parry’s third Arctic expedition, found that he could

-converse with a man across the harbour of Port Bowen, a distance

-of 6696 feet, or about one mile and a quarter. Dr. Young

-records that at Gibraltar the human voice has been heard at a

-distance of ten miles. If sound be prevented from spreading

-and losing itself in the air, either by a pipe or an extensive flat

-surface, as a wall or still water, it may be conveyed to a great

-distance. Biot heard a flute clearly through a tube of cast-iron

-(the water-pipes of Paris) 3120 feet long: the lowest whisper was

-distinctly heard; indeed, the only way not to be heard was not

-to speak at all.</p>

-

-<h3>THE ROAR OF NIAGARA.</h3>

-

-<p>The very nature of the sound of running water pronounces

-its origin to be the bursting of bubbles: the impact of water

-against water is a comparatively subordinate cause, and could

-never of itself occasion the murmur of a brook; whereas, in

-streams which Dr. Tyndall has examined, he, in all cases where

-a ripple was heard, discovered bubbles caused by the broken

-column of water. Now, were Niagara continuous, and without

-lateral vibration, it would be as silent as a cataract of ice. In

-all probability, it has its “contracted sections,” after passing

-which it is broken into detached masses, which, plunging successively

-upon the air-bladders formed by their precursors, suddenly

-liberate their contents, and thus create <i>the thunder of the

-waterfall</i>.</p>

-

-<h3>FIGURES PRODUCED BY SOUND.</h3>

-

-<p>Stretch a sheet of wet paper over the mouth of a glass tumbler

-which has a footstalk, and glue or paste the paper at the

-edges. When the paper is dry, strew dry sand thinly upon its

-surface. Place the tumbler on a table, and hold immediately

-above it, and parallel to the paper, a plate of glass, which

-you also strew with sand, having previously rubbed the edges

-smooth with emery powder. Draw a violin-bow along any

-part of the edges; and as the sand upon the glass is made to

-vibrate, it will form various figures, which will be accurately

-imitated by the sand upon the paper; or if a violin or flute be

-played within a few inches of the paper, they will cause the

-sand upon its surface to form regular lines and figures.</p>

-

-<h3>THE TUNING-FORK A FLUTE-PLAYER.</h3>

-

-<p>Take a common tuning-fork, and on one of its branches

-fasten with sealing-wax a circular piece of card of the size of

-a small wafer, or sufficient nearly to cover the aperture of a

-pipe, as the sliding of the upper end of a flute with the mouth<span class="pagenum"><a name="Page_29" id="Page_29">29</a></span>

-stopped: it may be tuned in unison with the loaded tuning-fork

-by means of the movable stopper or card, or the fork may

-be loaded till the unison is perfect. Then set the fork in vibration

-by a blow on the unloaded branch, and hold the card

-closely over the mouth of the pipe, as in the engraving, when

-a note of surprising clearness and strength will be heard. Indeed

-a flute may be made to “speak” perfectly well, by holding

-close to the opening a vibrating tuning-fork, while the fingering

-proper to the note of the fork is at the same time performed.</p>

-

-<h3>THEORY OF THE JEW’S HARP.</h3>

-

-<p>If you cause the tongue of this little instrument to vibrate,

-it will produce a very low sound; but if you place it before a

-cavity (as the mouth) containing a column of air, which vibrates

-much faster, but in the proportion of any simple multiple,

-it will then produce other higher sounds, dependent upon

-the reciprocation of that portion of the air. Now the bulk of

-air in the mouth can be altered in its form, size, and other circumstances,

-so as to produce by reciprocation many different

-sounds; and these are the sounds belonging to the Jew’s Harp.</p>

-

-<p>A proof of this fact has been given by Mr. Eulenstein, who

-fitted into a long metallic tube a piston, which being moved,

-could be made to lengthen or shorten the efficient column of

-air within at pleasure. A Jew’s Harp was then so fixed that

-it could be made to vibrate before the mouth of the tube, and

-it was found that the column of air produced a series of sounds,

-according as it was lengthened or shortened; a sound being

-produced whenever the length of the column was such that its

-vibrations were a multiple of those of the Jew’s Harp.</p>

-

-<h3>SOLAR AND ARTIFICIAL LIGHT COMPARED.</h3>

-

-<p>The most intensely ignited solid (produced by the flame of

-Lieutenant Drummond’s oxy-hydrogen lamp directed against a

-surface of chalk) appears only as black spots on the disc of the

-sun, when held between it and the eye; or in other words,

-Drummond’s light is to the light of the sun’s disc as 1 to 146.

-Hence we are doubly struck by the felicity with which Galileo,

-as early as 1612, by a series of conclusions on the smallness of

-the distance from the sun at which the disc of Venus was no

-longer visible to the naked eye, arrived at the result that the

-blackest nucleus of the sun’s spots was more luminous than

-the brightest portions of the full moon. (See “The Sun’s

-Light compared with Terrestrial Lights,” in <i>Things not generally

-Known</i>, pp. 4, 5.)</p>

-

-<h3>SOURCE OF LIGHT.</h3>

-

-<p>Mr. Robert Hunt, in a lecture delivered by him at the

-Russell Institution, “On the Physics of a Sunbeam,” mentions<span class="pagenum"><a name="Page_30" id="Page_30">30</a></span>

-some experiments by Lord Brougham on the sunbeam, in which,

-by placing the edge of a sharp knife just within the limit of

-the light, the ray was inflected from its previous direction, and

-coloured red; and when another knife was placed on the opposite

-side, it was deflected, and the colour was blue. These

-experiments (says Mr. Hunt) seem to confirm Sir Isaac Newton’s

-theory, that light is a fluid emitted from the sun.</p>

-

-<h3>THE UNDULATORY SCALE OF LIGHT.</h3>

-

-<p>The white light of the sun is well known to be composed of

-several coloured rays; or rather, according to the theory of

-undulations, when the rate at which a ray vibrates is altered,

-a different sensation is produced upon the optic nerve. The

-analytical examination of this question shows that to produce

-a red colour the ray of light must give 37,640 undulations in

-an inch, and 458,000,000,000,000 in a second. Yellow light requires

-44,000 undulations in an inch, and 535,000,000,000,000

-in a second; whilst the effect of blue results from 51,110 undulations

-within an inch, and 622,000,000,000,000 of waves in

-a second of time.&mdash;<i>Hunt’s Poetry of Science.</i></p>

-

-<h3>VISIBILITY OF OBJECTS.</h3>

-

-<p>In terrestrial objects, the form, no less than the modes of

-illumination, determines the magnitude of the smallest angle

-of vision for the naked eye. Adams very correctly observed

-that a long and slender staff can be seen at a much greater

-distance than a square whose sides are equal to the diameter of

-the staff. A stripe may be distinguished at a greater distance

-than a spot, even when both are of the same diameter.</p>

-

-<p>The <i>minimum</i> optical visual angle at which terrestrial objects

-can be recognised by the naked eye has been gradually

-estimated lower and lower, from the time when Robert Hooke

-fixed it exactly at a full minute, and Tobias Meyer required

-34″ to perceive a black speck on white paper, to the period

-of Leuwenhoeck’s experiments with spiders’ threads, which are

-visible to ordinary sight at an angle of 4″·7. In Hueck’s most

-accurate experiments on the problem of the movement of the

-crystalline lens, white lines on a black ground were seen at an

-angle of 1″·2; a spider’s thread at 0″·6; and a fine glistening

-wire at scarcely 0″·2.</p>

-

-<blockquote>

-

-<p>Humboldt, when at Chillo, near Quito, where the crests of the

-volcano of Pichincha lay at a horizontal distance of 90,000 feet, was

-much struck by the circumstance that the Indians standing near distinguished

-the figure of Bonpland (then on an expedition to the volcano),

-as a white point moving on the black basaltic sides of the rock, sooner

-than Humboldt could discover him with a telescope. Bonpland was

-enveloped in a white cotton poncho: assuming the breadth across the

-shoulders to vary from three to five feet, according as the mantle clung<span class="pagenum"><a name="Page_31" id="Page_31">31</a></span>

-to the figure or fluttered in the breeze, and judging from the known

-distance, the angle at which the moving object could be distinctly seen

-varied from 7″ to 12″. White objects on a black ground are, according

-to Hueck, distinguished at a greater distance than black objects on a

-white ground.</p>

-

-<p>Gauss’s heliotrope light has been seen with the naked eye reflected

-from the Brocken on Hobenhagen at a distance of about 227,000 feet,

-or more than 42 miles; being frequently visible at points in which the

-apparent breadth of a three-inch mirror was only 0″·43.</p></blockquote>

-

-<h3>THE SMALLEST BRIGHT BODIES.</h3>

-

-<p>Ehrenberg has found from experiments on the dust of diamonds,

-that a diamond superficies of 1/100th of a line in diameter

-presents a much more vivid light to the naked eye than one of

-quicksilver of the same diameter. On pressing small globules

-of quicksilver on a glass micrometer, he easily obtained smaller

-globules of the 1/100th to the 1/2000th of a line in diameter. In

-the sunshine he could only discern the reflection of light, and

-the existence of such globules as were 1/300th of a line in diameter,

-with the naked eye. Smaller ones did not affect his

-eye; but he remarked that the actual bright part of the globule

-did not amount to more than 1/900th of a line in diameter.

-Spider threads of 1/2000th in diameter were still discernible

-from their lustre. Ehrenberg concludes that there are in organic

-bodies magnitudes capable of direct proof which are in

-diameter 1/100000 of a line; and others, that can be indirectly

-proved, which may be less than a six-millionth part of a Parisian

-line in diameter.</p>

-

-<h3>VELOCITY OF LIGHT.</h3>

-

-<p>It is scarcely possible so to strain the imagination as to conceive

-the Velocity with which Light travels. “What mere

-assertion will make any man believe,” asks Sir John Herschel,

-“that in one second of time, in one beat of the pendulum of

-a clock, a ray of light travels over 192,000 miles; and would

-therefore perform the tour of the world in about the same time

-that it requires to wink with our eyelids, and in much less time

-than a swift runner occupies in taking a single stride?” Were

-a cannon-ball shot directly towards the sun, and were it to maintain

-its full speed, it would be twenty years in reaching it; and

-yet light travels through this space in seven or eight minutes.</p>

-

-<p>The result given in the <i>Annuaire</i> for 1842 for the velocity

-of light in a second is 77,000 leagues, which corresponds to

-215,834 miles; while that obtained at the Pulkowa Observatory

-is 189,746 miles. William Richardson gives as the result of the

-passage of light from the sun to the earth 8´ 19″·28, from which

-we obtain a velocity of 215,392 miles in a second.&mdash;<i>Memoirs of

-the Astronomical Society</i>, vol. iv.</p>

-

-<p><span class="pagenum"><a name="Page_32" id="Page_32">32</a></span>

-In other words, light travels a distance equal to eight times

-the circumference of the earth between two beats of a clock.

-This is a prodigious velocity; but the measure of it is very certain.&mdash;<i>Professor

-Airy.</i></p>

-

-<p>The navigator who has measured the earth’s circuit by his

-hourly progress, or the astronomer who has paced a degree of

-the meridian, can alone form a clear idea of velocity, when we

-tell him that light moves through a space equal to the circumference

-of the earth in <i>the eighth part of a second</i>&mdash;in the twinkling

-of an eye.</p>

-

-<blockquote>

-

-<p>Could an observer, placed in the centre of the earth, see this moving

-light, as it describes the earth’s circumference, it would appear a luminous

-ring; that is, the impression of the light at the commencement of

-its journey would continue on the retina till the light had completed its

-circuit. Nay, since the impression of light continues longer than the

-<i>fourth</i> part of a second, <i>two</i> luminous rings would be seen, provided the

-light made <i>two</i> rounds of the earth, and in paths not coincident.</p></blockquote>

-

-<h3>APPARATUS FOR THE MEASUREMENT OF LIGHT.</h3>

-

-<p>Humboldt enumerates the following different methods

-adopted for the Measurement of Light: a comparison of the

-shadows of artificial lights, differing in numbers and distance;

-diaphragms; plane-glasses of different thickness and colour;

-artificial stars formed by reflection on glass spheres; the juxtaposition

-of two seven-feet telescopes, separated by a distance

-which the observer could pass in about a second; reflecting instruments

-in which two stars can be simultaneously seen and

-compared, when the telescope has been so adjusted that the

-star gives two images of like intensity; an apparatus having

-(in front of the object-glass) a mirror and diaphragms, whose

-rotation is measured on a ring; telescopes with divided object-glasses,

-on either half of which the stellar light is received

-through a prism; astrometers, in which a prism reflects the

-image of the moon or Jupiter, and concentrates it through a

-lens at different distances into a star more or less bright.&mdash;<i>Cosmos</i>,

-vol. iii.</p>

-

-<h3>HOW FIZEAU MEASURED THE VELOCITY OF LIGHT.</h3>

-

-<p>This distinguished physicist has submitted the Velocity of

-Light to terrestrial measurement by means of an ingeniously

-constructed apparatus, in which artificial light (resembling

-stellar light), generated from oxygen and hydrogen, is made

-to pass back, by means of a mirror, over a distance of 28,321

-feet to the same point from which it emanated. A disc, having

-720 teeth, which made 12·6 rotations in a second, alternately

-obscured the ray of light and allowed it to be seen

-between the teeth on the margin. It was supposed, from the

-marking of a counter, that the artificial light traversed 56,642<span class="pagenum"><a name="Page_33" id="Page_33">33</a></span>

-feet, or the distance to and from the stations, in 1/1800th part of

-a second, whence we obtain a velocity of 191,460 miles in a second.<a name="FNanchor_12" id="FNanchor_12" href="#Footnote_12" class="fnanchor">12</a>

-This result approximates most closely to Delambre’s

-(which was 189,173 miles), as obtained from Jupiter’s satellites.</p>

-

-<blockquote>

-

-<p>The invention of the rotating mirror is due to Wheatstone, who made

-an experiment with it to determine the velocity of the propagation of the

-discharge of a Leyden battery. The most striking application of the

-idea was made by Fizeau and Foucault, in 1853, in carrying out a proposition

-made by Arago, soon after the invention of the mirror: we have

-here determined in a distance of twelve feet no less than the velocity

-with which light is propagated, which is known to be nearly 200,000

-miles a second; the distance mentioned corresponds therefore to the

-77-millionth part of a second. The object of these measurements was

-to compare the velocity of light in air with its velocity in water; which,

-when the length is greater, is not sufficiently transparent. The most

-complete optical and mechanical aids are here necessary: the mirror of

-Foucault made from 600 to 800 revolutions in a second, while that of

-Fizeau performed 1200 to 1500 in the same time.&mdash;<i>Prof. Helmholtz on

-the Methods of Measuring very small Portions of Time.</i></p></blockquote>

-

-<h3>WHAT IS DONE BY POLARISATION OF LIGHT.</h3>

-

-<p>Malus, in 1808, was led by a casual observation of the light

-of the setting sun, reflected from the windows of the Palais de

-Luxembourg, at Paris, to investigate more thoroughly the phenomena

-of double refraction, of ordinary and of chromatic polarisation,

-of interference and of diffraction of light. Among

-his results may be reckoned the means of distinguishing between

-direct and reflected light; the power of penetrating, as it were,

-into the constitution of the body of the sun and of its luminous

-envelopes; of measuring the pressure of atmospheric strata,

-and even the smallest amount of water they contain; of ascertaining

-the depths of the ocean and its rocks by means of a

-tourmaline plate; and in accordance with Newton’s prediction,

-of comparing the chemical composition of several substances

-with their optical effects.</p>

-

-<blockquote>

-

-<p>Arago, in a letter to Humboldt, states that by the aid of his polariscope,

-he discovered, before 1820, that the light of all terrestrial objects

-in a state of incandescence, whether they be solid or liquid, is natural,

-so long as it emanates from the object in perpendicular rays. On the

-other hand, if such light emanate at an acute angle, it presents manifest

-proofs of polarisation. This led M. Arago to the remarkable conclusion,

-that light is not generated on the surface of bodies only, but that

-some portion is actually engendered within the substance itself, even in

-the case of platinum.</p></blockquote>

-

-<p>A ray of light which reaches our eyes after traversing many

-millions of miles, from, the remotest regions of heaven, announces,

-as it were of itself, in the polariscope, whether it is<span class="pagenum"><a name="Page_34" id="Page_34">34</a></span>

-reflected or refracted, whether it emanates from a solid or fluid

-or gaseous body; it announces even the degree of its intensity.&mdash;<i>Humboldt’s

-Cosmos</i>, vols. i. and ii.</p>

-

-<h3>MINUTENESS OF LIGHT.</h3>

-

-<p>There is something wonderful, says Arago, in the experiments

-which have led natural philosophers legitimately to talk

-of the different sides of a ray of light; and to show that millions

-and millions of these rays can simultaneously pass through

-the eye of a needle without interfering with each other!</p>

-

-<h3>THE IMPORTANCE OF LIGHT.</h3>

-

-<p>Light affects the respiration of animals just as it affects the

-respiration of plants. This is novel doctrine, but it is demonstrable.

-In the day-time we expire more carbonic acid than

-during the night; a fact known to physiologists, who explain

-it as the effect of sleep: but the difference is mainly owing to

-the presence or absence of sunlight; for sleep, as sleep, <i>increases</i>,

-instead of diminishing, the amount of carbonic acid expired,

-and a man sleeping will expire more carbonic acid than if he

-lies quietly awake under the same conditions of light and temperature;

-so that if less is expired during the night than during

-the day, the reason cannot be sleep, but the absence of light.

-Now we understand why men are sickly and stunted who live

-in narrow streets, alleys, and cellars, compared with those who,

-under similar conditions of poverty and dirt, live in the sunlight.&mdash;<i>Blackwood’s

-Edinburgh Magazine</i>, 1858.</p>

-

-<blockquote>

-

-<p>The influence of light on the colours of organised creation is well

-shown in the sea. Near the shores we find seaweeds of the most beautiful

-hues, particularly on the rocks which are left dry by the tides; and

-the rich tints of the actiniæ which inhabit shallow water must often

-have been observed. The fishes which swim near the surface are also

-distinguished by the variety of their colours, whereas those which live at

-greater depths are gray, brown, or black. It has been found that after

-a certain depth, where the quantity of light is so reduced that a mere

-twilight prevails, the inhabitants of the ocean become nearly colourless.&mdash;<i>Hunt’s

-Poetry of Science.</i></p></blockquote>

-

-<h3>ACTION OF LIGHT ON MUSCULAR FIBRES.</h3>

-

-<p>That light is capable of acting on muscular fibres, independently

-of the influence of the nerves, was mentioned by several

-of the old anatomists, but repudiated by later authorities. M.

-Brown Séquard has, however, proved to the Royal Society that

-some portions of muscular fibre&mdash;the iris of the eye, for example&mdash;are

-affected by light independently of any reflex action of the

-nerves, thereby confirming former experiences. The effect is

-produced by the illuminating rays only, the chemical and heat

-rays remaining neutral. And not least remarkable is the fact,<span class="pagenum"><a name="Page_35" id="Page_35">35</a></span>

-that the iris of an eel showed itself susceptible of the excitement

-<i>sixteen days after the eyes were removed from the creature’s

-head</i>. So far as is yet known, this muscle is the only one on

-which light thus takes effect.&mdash;<i>Phil. Trans. 1857.</i></p>

-

-<h3>LIGHT NIGHTS.</h3>

-

-<p>It is not possible, as well-attested facts prove, perfectly to

-explain the operations at work in the much-contested upper

-boundaries of our atmosphere. The extraordinary lightness of

-whole nights in the year 1831, during which small print might

-be read at midnight in the latitudes of Italy and the north of

-Germany, is a fact directly at variance with all that we know,

-according to the most recent and acute researches on the crepuscular

-theory and the height of the atmosphere.&mdash;<i>Biot.</i></p>

-

-<h3>PHOSPHORESCENCE OF PLANTS.</h3>

-

-<p>Mr. Hunt recounts these striking instances. The leaves of

-the <i>œnothera macrocarpa</i> are said to exhibit phosphoric light

-when the air is highly charged with electricity. The agarics

-of the olive-grounds of Montpelier too have been observed to be

-luminous at night; but they are said to exhibit no light, even

-in darkness, <i>during the day</i>. The subterranean passages of the

-coal-mines near Dresden are illuminated by the phosphorescent

-light of the <i>rhizomorpha phosphoreus</i>, a peculiar fungus.

-On the leaves of the Pindoba palm grows a species of agaric

-which is exceedingly luminous at night; and many varieties

-of the lichens, creeping along the roofs of caverns, lend to them

-an air of enchantment by the soft and clear light which they

-diffuse. In a small cave near Penryn, a luminous moss is

-abundant; it is also found in the mines of Hesse. According

-to Heinzmann, the <i>rhizomorpha subterranea</i> and <i>aidulæ</i> are also

-phosphorescent.&mdash;See <i>Poetry of Science</i>.</p>

-

-<h3>PHOSPHORESCENCE OF THE SEA.</h3>

-

-<p>By microscopic examination of the myriads of minute insects

-which cause this phenomenon, no other fact has been elicited

-than that they contain a fluid which, when squeezed out, leaves

-a train of light upon the surface of the water. The creatures

-appear almost invariably on the eve of some change of weather,

-which would lead us to suppose that their luminous phenomena

-must be connected with electrical excitation; and of this Mr. C.

-Peach of Fowey has furnished the most satisfactory proofs yet

-obtained.<a name="FNanchor_13" id="FNanchor_13" href="#Footnote_13" class="fnanchor">13</a></p>

-

-<h3>LIGHT FROM THE JUICE OF A PLANT.</h3>

-

-<p>In Brazil has been observed a plant, conjectured to be an<span class="pagenum"><a name="Page_36" id="Page_36">36</a></span>

-Euphorbium, very remarkable for the light which it yields when

-cut. It contains a milky juice, which exudes as soon as the

-plant is wounded, and appears luminous for several seconds.</p>

-

-<h3>LIGHT FROM FUNGUS.</h3>

-

-<p>Phosphorescent funguses have been found in Brazil by Mr.

-Gardner, growing on the decaying leaves of a dwarf palm. They

-vary from one to two inches across, and the whole plant gives

-out at night a bright phosphorescent light, of a pale greenish

-hue, similar to that emitted by fire-flies and phosphorescent

-marine animals. The light given out by a few of these fungi

-in a dark room is sufficient to read by. A very large phosphorescent

-species is occasionally found in the Swan River colony.</p>

-

-<h3>LIGHT FROM BUTTONS.</h3>

-

-<p>Upon highly polished gilt buttons no figure whatever can

-be seen by the most careful examination; yet, when they are

-made to reflect the light of the sun or of a candle upon a piece

-of paper held close to them, they give a beautiful geometrical

-figure, with ten rays issuing from the centre, and terminating

-in a luminous rim.</p>

-

-<h3>COLOURS OF SCRATCHES.</h3>

-

-<p>An extremely fine scratch on a well-polished surface may

-be regarded as having a concave, cylindrical, or at least a

-curved surface, capable of reflecting light in all directions; this

-is evident, for it is visible in all directions. Hence a single

-scratch or furrow in a surface may produce colours by the interference

-of the rays reflected from its opposite edges. Examine

-a spider’s thread in the sunshine, and it will gleam with vivid

-colours. These may arise from a similar cause; or from the

-thread itself, as spun by the animal, consisting of several

-threads agglutinated together, and thus presenting, not a cylindrical,

-but a furrowed surface.</p>

-

-<h3>MAGIC BUST.</h3>

-

-<p>Sir David Brewster has shown how the rigid features of a

-white bust may be made to move and vary their expression,

-sometimes smiling and sometimes frowning, by moving rapidly

-in front of the bust a bright light, so as to make the lights and

-shadows take every possible direction and various degrees of

-intensity; and if the bust be placed before a concave mirror,

-its image may be made to do still more when it is cast upon

-wreaths of smoke.</p>

-

-<h3>COLOURS HIT MOST FREQUENTLY DURING BATTLE.</h3>

-

-<p>It would appear from numerous observations that soldiers<span class="pagenum"><a name="Page_37" id="Page_37">37</a></span>

-are hit during battle according to the colour of their dress in

-the following order: red is the most fatal colour; the least

-fatal, Austrian gray. The proportions are, red, 12; rifle-green,

-7; brown, 6; Austrian bluish-gray, 5.&mdash;<i>Jameson’s Journal</i>, 1853.</p>

-

-<h3>TRANSMUTATION OF TOPAZ.</h3>

-

-<p>Yellow topazes may be converted into pink by heat; but it

-is a mistake to suppose that in the process the yellow colour is

-changed into pink: the fact is, that one of the pencils being

-yellow and the other pink, the yellow is discharged by heat,

-thus leaving the pink unimpaired.</p>

-

-<h3>COLOURS AND TINTS.</h3>

-

-<p>M. Chevreul, the <i>Directeur des Gobelins</i>, has presented to the

-French Academy a plan for a universal chromatic scale, and a

-methodical classification of all imaginable colours. Mayer, a

-professor at Göttingen, calculated that the different combinations

-of primitive colours produced 819 different tints; but M.

-Chevreul established not less than 14,424, all very distinct and

-easily recognised,&mdash;all of course proceeding from the three primitive

-simple colours of the solar spectrum, red, yellow, and

-blue. For example, he states that in the violet there are twenty-eight

-colours, and in the dahlia forty-two.</p>

-

-<h3>OBJECTS REALLY OF NO COLOUR.</h3>

-

-<p>A body appears to be of the colour which it reflects; as we

-see it only by reflected rays, it can but appear of the colour

-of those rays. Thus grass is green because it absorbs all except

-the green rays. Flowers, in the same manner, reflect the various

-colours of which they appear to us: the rose, the red rays;

-the violet, the blue; the daffodil, the yellow, &amp;c. But these

-are not the permanent colours of the grass and flowers; for

-wherever you see these colours, the objects must be illuminated;

-and light, from whatever source it proceeds, is of the same nature,

-composed of the various coloured rays which paint the

-grass, the flowers, and every coloured object in nature. Objects

-in the dark have no colour, or are black, which is the same

-thing. You can never see objects without light. Light is composed

-of colours, therefore there can be no light without colours;

-and though every object is black or without colour in

-the dark, it becomes coloured as soon as it becomes visible.</p>

-

-<h3>THE DIORAMA&mdash;WHY SO PERFECT AN ILLUSION.</h3>

-

-<p>Because when an object is viewed at so great a distance

-that the optic axes of both eyes are sensibly parallel when

-directed towards it, the perspective projections of it, seen by<span class="pagenum"><a name="Page_38" id="Page_38">38</a></span>

-each eye separately, are similar; and the appearance to the

-two eyes is precisely the same as when the object is seen by

-one eye only. There is, in such case, no difference between

-the visual appearance of an object in relief and its perspective

-projection on a plane surface; hence pictorial representations

-of distant objects, when those circumstances which would prevent

-or disturb the illusion are carefully excluded, may be

-rendered such perfect resemblances of the objects they are intended

-to represent as to be mistaken for them. The Diorama

-is an instance of this.&mdash;<i>Professor Wheatstone</i>; <i>Philosophical

-Transactions</i>, 1838.</p>

-

-<h3>CURIOUS OPTICAL EFFECTS AT THE CAPE.</h3>

-

-<p>Sir John Herschel, in his observatory at Feldhausen, at the

-base of the Table Mountain, witnessed several curious optical

-effects, arising from peculiar conditions of the atmosphere incident

-to the climate of the Cape. In the hot season “the

-nights are for the most part superb;” but occasionally, during

-the excessive heat and dryness of the sandy plains, “the optical

-tranquillity of the air” is greatly disturbed. In some

-cases, the images of the stars are violently dilated into nebular

-balls or puffs of 15′ in diameter; on other occasions they form

-“soft, round, quiet pellets of 3′ or 4′ diameter,” resembling

-planetary nebulæ. In the cooler months the tranquillity of

-the image and the sharpness of vision are such, that hardly any

-limit is set to magnifying power but that which arises from

-the aberration of the specula. On occasions like these, optical

-phenomena of extraordinary splendour are produced by viewing

-a bright star through a diaphragm of cardboard or zinc pierced

-in regular patterns of circular holes by machinery: these phenomena

-surprise and delight every person that sees them.

-When close double stars are viewed with the telescope, with a

-diaphragm in the form of an equilateral triangle, the discs of

-the two stars, which are exact circles, have a clearness and

-perfection almost incredible.</p>

-

-<h3>THE TELESCOPE AND THE MICROSCOPE.</h3>

-

-<p>So singular is the position of the Telescope and the Microscope

-among the great inventions of the age, that no other

-process but that which they embody could make the slightest

-approximation to the secrets which they disclose. The steam-engine

-might have been imperfectly replaced by an air or an

-ether-engine; and a highly elastic fluid might have been, and

-may yet be, found, which shall impel the “rapid car,” or drag

-the merchant-ship over the globe. The electric telegraph,

-now so perfect and unerring, might have spoken to us in the<span class="pagenum"><a name="Page_39" id="Page_39">39</a></span>

-rude “language of chimes;” or sound, in place of electricity,

-might have passed along the metallic path, and appealed to

-the ear in place of the eye. For the printing-press and the

-typographic art might have been found a substitute, however

-poor, in the lithographic process; and knowledge might have

-been widely diffused by the photographic printing powers of

-the sun, or even artificial light. But without the telescope and

-the microscope, the human eye would have struggled in vain to

-study the worlds beyond our own, and the elaborate structures

-of the organic and inorganic creation could never have been

-revealed.&mdash;<i>North-British Review</i>, No. 50.</p>

-

-<h3>INVENTION OF THE MICROSCOPE.</h3>

-

-<p>The earliest magnifying lens of which we have any knowledge

-was one rudely made of rock-crystal, which Mr. Layard

-found, among a number of glass bowls, in the north-west palace

-of Nimroud; but no similar lens has been found or described

-to induce us to believe that the microscope, either single or

-compound, was invented and used as an instrument previous

-to the commencement of the seventeenth century. In the

-beginning of the first century, however, Seneca alludes to the

-magnifying power of a glass globe filled with water; but as he

-only states that it made small and indistinct letters appear

-larger and more distinct, we cannot consider such a casual remark

-as the invention of the single microscope, though it might

-have led the observer to try the effect of smaller globes, and

-thus obtain magnifying powers sufficient to discover phenomena

-otherwise invisible.</p>

-

-<p>Lenses of glass were undoubtedly in existence at the time

-of Pliny; but at that period, and for many centuries afterwards,

-they appear to have been used only as burning or as

-reading glasses; and no attempt seems to have been made to

-form them of so small a size as to entitle them to be regarded

-even as the precursors of the single microscope.&mdash;<i>North-British

-Review</i>, No. 50.</p>

-

-<blockquote>

-

-<p>The <i>rock-crystal lens</i> found at Nineveh was examined by Sir David

-Brewster. It was not entirely circular in its aperture. Its general form

-was that of a plano-convex lens, the plane side having been formed of one

-of the original faces of the six-sided crystal quartz, as Sir David ascertained

-by its action on polarised light: this was badly polished and

-scratched. The convex face of the lens had not been ground in a dish-shaped

-tool, in the manner in which lenses are now formed, but was

-shaped on a lapidary’s wheel, or in some such manner. Hence it was

-unequally thick; but its extreme thickness was 2/10ths of an inch, its

-focal length being 4½ inches. It had twelve remains of cavities, which

-had originally contained liquids or condensed gases. Sir David has

-assigned reasons why this could not be looked upon as an ornament, but

-a true optical lens. In the same ruins were found some decomposed

-glass.</p></blockquote>

-

-<p><span class="pagenum"><a name="Page_40" id="Page_40">40</a></span></p>

-

-<h3>HOW TO MAKE THE FISH-EYE MICROSCOPE.</h3>

-

-<p>Very good microscopes may be made with the crystalline

-lenses of fish, birds, and quadrupeds. As the lens of fishes is

-spherical or spheroidal, it is absolutely necessary, previous to

-its use, to determine its optical axis and the axis of vision

-of the eye from which it is taken, and place the lens in such a

-manner that its axis is a continuation of the axis of our own

-eye. In no other direction but this is the albumen of which

-the lens consists symmetrically disposed in laminæ of equal

-density round a given line, which is the axis of the lens; and

-in no other direction does the gradation of density, by which

-the spherical aberration is corrected, preserve a proper relation

-to the axis of vision.</p>

-

-<blockquote>

-

-<p>When the lens of any small fish, such as a minnow, a par, or trout,

-has been taken out, along with the adhering vitreous humour, from the

-eye-ball by cutting the sclerotic coat with a pair of scissors, it should be

-placed upon a piece of fine silver-paper previously freed from its minute

-adhering fibres. The absorbent nature of the paper will assist in removing

-all the vitreous humour from the lens; and when this is carefully

-done, by rolling it about with another piece of silver-paper, there

-will still remain, round or near the equator of the lens, a black ridge,

-consisting of the processes by which it was suspended in the eye-ball.

-The black circle points out to us the true axis of the lens, which is perpendicular

-to a plane passing through it. When the small crystalline

-has been freed from all the adhering vitreous humour, the capsule which

-contains it will have a surface as fine as a pellicle of fluid. It is then to

-be dropped from the paper into a cavity formed by a brass rim, and its

-position changed till the black circle is parallel to the circular rim, in

-which case only the axis of the lens will be a continuation of the axis of

-the observer’s eye.&mdash;<i>Edin. Jour. Science</i>, vol. ii.</p></blockquote>

-

-<h3>LEUWENHOECK’S MICROSCOPES.</h3>

-

-<p>Leuwenhoeck, the father of microscopical discovery, communicated

-to the Royal Society, in 1673, a description of the

-structure of a bee and a louse, seen by aid of his improved microscopes;

-and from this period until his decease in 1723, he

-regularly transmitted to the society his microscopical observations

-and discoveries, so that 375 of his papers and letters are

-preserved in the society’s archives, extending over fifty years.

-He further bequeathed to the Royal Society a cabinet of twenty-six

-microscopes, which he had ground himself and set in silver,

-mostly extracted by him from minerals; these microscopes were

-exhibited to Peter the Great when he was at Delft in 1698. In

-acknowledging the bequest, the council of the Royal Society,

-in 1724, presented Leuwenhoeck’s daughter with a handsome

-silver bowl, bearing the arms of the society.&mdash;<i>Weld’s History

-of the Royal Society</i>, vol. i.</p>

-

-<h3>DIAMOND LENSES FOR MICROSCOPES.</h3>

-

-<p>In recommending the employment of Diamond and other<span class="pagenum"><a name="Page_41" id="Page_41">41</a></span>

-gems in the construction of Microscopes, Sir David Brewster

-has been met with the objection that they are too expensive for

-such a purpose; and, says Sir David, “they certainly are for

-instruments intended merely to instruct and amuse. But if

-we desire to make great discoveries, to unfold secrets yet hid

-in the cells of plants and animals, we must not grudge even a

-diamond to reveal them. If Mr. Cooper and Sir James South

-have given a couple of thousand pounds a piece for a refracting

-telescope, in order to study what have been miscalled ‘dots’

-and ‘lumps’ of light on the sky; and if Lord Rosse has expended

-far greater sums on a reflecting telescope for analysing

-what has been called ‘sparks of mud and vapour’ encumbering

-the azure purity of the heavens,&mdash;why should not other philosophers

-open their purse, if they have one, and other noblemen

-sacrifice some of their household jewels, to resolve the microscopic

-structures of our own real world, and disclose secrets

-which the Almighty must have intended that we should know?”&mdash;<i>Proceedings

-of the British Association</i>, 1857.</p>

-

-<h3>THE EYE AND THE BRAIN SEEN THROUGH A MICROSCOPE.</h3>

-

-<p>By a microscopic examination of the retina and optic nerve

-and the brain, M. Bauer found them to consist of globules of

-1/2800th to 1/4000th an inch diameter, united by a transparent

-viscid and coagulable gelatinous fluid.</p>

-

-<h3>MICROSCOPICAL EXAMINATION OF THE HAIR.</h3>

-

-<p>If a hair be drawn between the finger and thumb, from the

-end to the root, it will be distinctly felt to give a greater resistance

-and a different sensation to that which is experienced

-when drawn the opposite way: in consequence, if the hair be

-rubbed between the fingers, it will only move one way (travelling

-in the direction of a line drawn from its termination to its

-origin from the head or body), so that each extremity may thus

-be easily distinguished, even in the dark, by the touch alone.</p>

-

-<p>The mystery is resolved by the achromatic microscope. A

-hair viewed on a dark ground as an <i>opaque</i> object with a high

-power, not less than that of a lens of one-thirtieth of an inch

-focus, and dully illuminated by a <i>cup</i>, the hair is seen to be indented

-with teeth somewhat resembling those of a coarse round

-rasp, but extremely irregular and rugged: as these incline all

-in one direction, like those of a common file, viz. from the

-origin of the hair towards its extremity, it sufficiently explains

-the above singular property.</p>

-

-<p>This is a singular proof of the acuteness of the sense of feeling,

-for the said teeth may be felt much more easily than they

-can be seen. We may thus understand why a razor will cut a

-hair in two much more easily when drawn against its teeth than

-in the opposite direction.&mdash;<i>Dr. Goring.</i></p>

-

-<p><span class="pagenum"><a name="Page_42" id="Page_42">42</a></span></p>

-

-<h3>THE MICROSCOPE AND THE SEA.</h3>

-

-<p>What myriads has the microscope revealed to us of the rich

-luxuriance of animal life in the ocean, and conveyed to our astonished

-senses a consciousness of the universality of life! In

-the oceanic depths every stratum of water is animated, and

-swarms with countless hosts of small luminiferous animalcules,

-mammaria, crustacea, peridinea, and circling nereides, which,

-when attracted to the surface by peculiar meteorological conditions,

-convert every wave into a foaming band of flashing light.</p>

-

-<h3>USE OF THE MICROSCOPE TO MINERALOGISTS.</h3>

-

-<p>M. Dufour has shown that an imponderable quantity of a

-substance can be crystallised; and that the crystals so obtained

-are quite characteristic of the substances, as of sugar, chloride

-of sodium, arsenic, and mercury. This process may be extremely

-valuable to the mineralogist and toxicologist when the

-substance for examination is too small to be submitted to tests.

-By aid of the microscope, also, shells are measured to the thousandth

-part of an inch.</p>

-

-<h3>FINE DOWN OF QUARTZ.</h3>

-

-<p>Sir David Brewster having broken in two a crystal of quartz

-of a smoky colour, found both surfaces of the fracture absolutely

-black; and the blackness appeared at first sight to be

-owing to a thin film of opaque matter which had insinuated

-itself into the crevice. This opinion, however, was untenable,

-as every part of the surface was black, and the two halves of the

-crystals could not have stuck together had the crevice extended

-across the whole section. Upon further examination Sir David

-found that the surface was perfectly transparent by transmitted

-light, and that the blackness of the surfaces arose from their

-being entirely composed of <i>a fine down of quartz</i>, or of short

-and slender filaments, whose diameter was so exceedingly small

-that they were incapable of reflecting a single ray of the strongest

-light; and they could not exceed the <i>one third of the millionth

-part of an inch</i>. This curious specimen is in the cabinet

-of her grace the Duchess of Gordon.</p>

-

-<h3>MICROSCOPIC WRITING.</h3>

-

-<p>Professor Kelland has shown, in Paris, on a spot no larger

-than the head of a small pin, by means of powerful microscopes,

-several specimens of distinct and beautiful writing, one of them

-containing the whole of the Lord’s Prayer written within this

-minute compass. In reference to this, two remarkable facts in

-Layard’s latest work on Nineveh show that the national records

-of Assyria were written on square bricks, in characters so small

-as scarcely to be legible without a microscope; in fact, a microscope,

-as we have just shown, was found in the ruins of Nimroud.</p>

-

-<p><span class="pagenum"><a name="Page_43" id="Page_43">43</a></span></p>

-

-<h3>HOW TO MAKE A MAGIC MIRROR.</h3>

-

-<p>Draw a figure with weak gum-water upon the surface of a

-convex mirror. The thin film of gum thus deposited on the

-outline or details of the figure will not be visible in dispersed

-daylight; but when made to reflect the rays of the sun, or those

-of a divergent pencil, will be beautifully displayed by the lines

-and tints occasioned by the diffraction of light, or the interference

-of the rays passing through the film with those which

-pass by it.</p>

-

-<h3>SIR DAVID BREWSTER’S KALEIDOSCOPE.</h3>

-

-<p>The idea of this instrument, constructed for the purpose of

-creating and exhibiting a variety of beautiful and perfectly

-symmetrical forms, first occurred to Sir David Brewster in 1814,

-when he was engaged in experiments on the polarisation of

-light by successive reflections between plates of glass. The

-reflectors were in some instances inclined to each other; and

-he had occasion to remark the circular arrangement of the

-images of a candle round a centre, or the multiplication of the

-sectors formed by the extremities of the glass plates. In repeating

-at a subsequent period the experiments of M. Biot on the

-action of fluids upon light, Sir David Brewster placed the fluids

-in a trough, formed by two plates of glass cemented together at

-an angle; and the eye being necessarily placed at one end, some

-of the cement, which had been pressed through between the

-plates, appeared to be arranged into a regular figure. The remarkable

-symmetry which it presented led to Dr. Brewster’s

-investigation of the cause of this phenomenon; and in so doing

-he discovered the leading principles of the Kaleidoscope.</p>

-

-<p>By the advice of his friends, Dr. Brewster took out a patent

-for his invention; in the specification of which he describes the

-kaleidoscope in two different forms. The instrument, however,

-having been shown to several opticians in London, became

-known before he could avail himself of his patent; and being

-simple in principle, it was at once largely manufactured. It is

-calculated that not less than 200,000 kaleidoscopes were sold

-in three months in London and Paris; though out of this number,

-Dr. Brewster says, not perhaps 1000 were constructed upon

-scientific principles, or were capable of giving any thing like a

-correct idea of the power of his kaleidoscope.</p>

-

-<h3>THE KALEIDOSCOPE THOUGHT TO BE ANTICIPATED.</h3>

-

-<p>In the seventh edition of a work on gardening and planting,

-published in 1739, by Richard Bradley, F.R.S., late Professor

-of Botany in the University of Cambridge, we find the

-following details of an invention, “by which the best designers<span class="pagenum"><a name="Page_44" id="Page_44">44</a></span>

-and draughtsmen may improve and help their fancies.

-They must choose two pieces of looking-glass of equal bigness,

-of the figure of a long square. These must be covered on the

-back with paper or silk, to prevent rubbing off the silver. This

-covering must be so put on that nothing of it appears about the

-edges of the bright side. The glasses being thus prepared, must

-be laid face to face, and hinged together so that they may be

-made to open and shut at pleasure like the leaves of a book.”

-After showing how various figures are to be looked at in these

-glasses under the same opening, and how the same figure may

-be varied under the different openings, the ingenious artist thus

-concludes: “If it should happen that the reader has any number

-of plans for parterres or wildernesses by him, he may by this

-method alter them at his pleasure, and produce such innumerable

-varieties as it is not possible the most able designer could

-ever have contrived.”</p>

-

-<h3>MAGIC OF PHOTOGRAPHY.</h3>

-

-<p>Professor Moser of Königsberg has discovered that all bodies,

-even in the dark, throw out invisible rays; and that these

-bodies, when placed at a small distance from polished surfaces

-of all kinds, depict themselves upon such surfaces in forms

-which remain invisible till they are developed by the human

-breath or by the vapours of mercury or iodine. Even if the

-sun’s image is made to pass over a plate of glass, the light

-tread of its rays will leave behind it an invisible track, which

-the human breath will instantly reveal.</p>

-

-<blockquote>

-

-<p>Among the early attempts to take pictures by the rays of the sun

-was a very interesting and successful experiment made by Dr. Thomas

-Young. In 1802, when Mr. Wedgewood was “making profiles by the

-agency of light,” and Sir Humphry Davy was “copying on prepared

-paper the images of small objects produced by means of the solar microscope,”

-Dr. Young was taking photographs upon paper dipped in a solution

-of nitrate of silver, of the coloured rings observed by Newton;

-and his experiments clearly proved that the agent was not the luminous

-rays in the sun’s light, but the invisible or chemical rays beyond the

-violet. This experiment is described in the Bakerian Lecture, 1803.</p>

-

-<p>Niepce (says Mr. Hunt) pursued a physical investigation of the curious

-change, and found that all bodies were influenced by this principle

-radiated from the sun. Daguerre<a name="FNanchor_14" id="FNanchor_14" href="#Footnote_14" class="fnanchor">14</a> produced effects from the solar pencil

-which no artist could approach; and Talbot and others extended the

-application. Herschel took up the inquiry; and he, with his usual<span class="pagenum"><a name="Page_45" id="Page_45">45</a></span>

-power of inductive search and of philosophical deduction, presented the

-world with a class of discoveries which showed how vast a field of investigation

-was opening for the younger races of mankind.</p>

-

-<p>The first attempts in photography, which were made at the instigation

-of M. Arago, by order of the French Government, to copy the

-Egyptian tombs and temples and the remains of the Aztecs in Central

-America, were failures. Although the photographers employed succeeded

-to admiration, in Paris, in producing pictures in a few minutes,

-they found often that an exposure of an hour was insufficient under the

-bright and glowing illumination of a southern sky.</p></blockquote>

-

-<h3>THE BEST SKY FOR PHOTOGRAPHY.</h3>

-

-<p>Contrary to all preconceived ideas, experience proves that

-the brighter the sky that shines above the camera the more

-tardy the action within it. Italy and Malta do their work

-slower than Paris. Under the brilliant light of a Mexican sun,

-half an hour is required to produce effects which in England

-would occupy but a minute. In the burning atmosphere of

-India, though photographical the year round, the process is

-comparatively slow and difficult to manage; while in the clear,

-beautiful, and moreover cool, light of the higher Alps of Europe,

-it has been proved that the production of a picture requires

-many more minutes, even with the most sensitive preparations,

-than in the murky atmosphere of London. Upon

-the whole, the temperate skies of this country may be pronounced

-favourable to photographic action; a fact for which

-the prevailing characteristic of our climate may partially account,

-humidity being an indispensable condition for the

-working state both of paper and chemicals.&mdash;<i>Quarterly Review</i>,

-No. 202.</p>

-

-<h3>PHOTOGRAPHIC EFFECTS OF LIGHTNING.</h3>

-

-<p>The following authenticated instances of this singular phenomenon

-have been communicated to the Royal Society by

-Andrés Poey, Director of the Observatory at Havana:</p>

-

-<blockquote>

-

-<p>Benjamin Franklin, in 1786, stated that about twenty years previous,

-a man who was standing opposite a tree that had just been struck

-by “a thunderbolt” had on his breast an exact representation of that

-tree.</p>

-

-<p>In the New-York <i>Journal of Commerce</i>, August 26th, 1853, it is related

-that “a little girl was standing at a window, before which was a

-young maple-tree; after a brilliant flash of lightning, a complete image

-of the tree was found imprinted on her body.”</p>

-

-<p>M. Raspail relates that, in 1855, a boy having climbed a tree for

-the purpose of robbing a bird’s nest, the tree was struck, and the boy

-thrown upon the ground; on his breast the image of the tree, with the

-bird and nest on one of its branches, appeared very plainly.</p>

-

-<p>M. Olioli, a learned Italian, brought before the Scientific Congress

-at Naples the following four instances: 1. In September 1825, the foremast

-of a brigantine in the Bay of St. Arniro was struck by lightning,

-when a sailor sitting under the mast was struck dead, and on his back<span class="pagenum"><a name="Page_46" id="Page_46">46</a></span>

-was found an impression of a horse-shoe, similar even in size to that

-fixed on the mast-head. 2. A sailor, standing in a similar position,

-was struck by lightning, and had on his left breast the impression of the

-number 4 4, with a dot between the two figures, just as they appeared at

-the extremity of one of the masts. 3. On the 9th October 1836, a young

-man was found struck by lightning; he had on a girdle, with some gold

-coins in it, which were imprinted on his skin in the order they were

-placed in the girdle,&mdash;a series of circles, with one point of contact, being

-plainly visible. 4. In 1847, Mme. Morosa, an Italian lady of Lugano,

-was sitting near a window during a thunderstorm, and perceived the

-commotion, but felt no injury; but a flower which happened to be in

-the path of the electric current was perfectly reproduced on one of her

-legs, and there remained permanently.</p>

-

-<p>M. Poey himself witnessed the following instance in Cuba. On July

-24th, 1852, a poplar-tree in a coffee-plantation was struck by lightning,

-and on one of the large dry leaves was found an exact representation

-of some pine-trees that lay 367 yards distant.</p></blockquote>

-

-<p>M. Poey considers these lightning impressions to have

-been produced in the same manner as the electric images obtained

-by Moser, Riess, Karster, Grove, Fox Talbot, and others,

-either by statical or dynamical electricity of different intensities.

-The fact that impressions are made through the garments

-is easily accounted for by their rough texture not preventing

-the lightning passing through them with the impression.

-To corroborate this view, M. Poey mentions an instance

-of lightning passing down a chimney into a trunk, in which

-was found an inch depth of soot, which must have passed

-through the wood itself.</p>

-

-<h3>PHOTOGRAPHIC SURVEYING.</h3>

-

-<p>During the summer of 1854, in the Baltic, the British

-steamers employed in examining the enemy’s coasts and fortifications

-took photographic views for reference and minute

-examination. With the steamer moving at the rate of fifteen

-knots an hour, the most perfect definitions of coasts and batteries

-were obtained. Outlines of the coasts, correct in height

-and distance, have been faithfully transcribed; and all details

-of the fortresses passed under this photographic review are accurately

-recorded.</p>

-

-<blockquote>

-

-<p>It is curious to reflect that the aids to photographic development all

-date within the last half-century, and are but little older than photography

-itself. It was not until 1811 that the chemical substance called

-iodine, on which the foundations of all popular photography rest, was

-discovered at all; bromine, the only other substance equally sensitive,

-not till 1826. The invention of the electro process was about simultaneous

-with that of photography itself. Gutta-percha only just preceded

-the substance of which collodion is made; the ether and chloroform,

-which are used in some methods, that of collodion. We say

-nothing of the optical improvements previously contrived or adapted

-for the purpose of the photograph: the achromatic lenses, which correct

-the discrepancy between the visual and chemical foci; the double<span class="pagenum"><a name="Page_47" id="Page_47">47</a></span>

-lenses, which increase the force of the action; the binocular lenses,

-which do the work of the stereoscope; nor of the innumerable other

-mechanical aids which have sprung up for its use.</p></blockquote>

-

-<h3>THE STEREOSCOPE AND THE PHOTOGRAPH.</h3>

-

-<p>When once the availability of one great primitive agent

-is worked out, it is easy to foresee how extensively it will assist

-in unravelling other secrets in natural science. The simple

-principle of the Stereoscope, for instance, might have been

-discovered a century ago, for the reasoning which led to it

-was independent of all the properties of light; but it could

-never have been illustrated, far less multiplied as it now is,

-without Photography. A few diagrams, of sufficient identity

-and difference to prove the truth of the principle, might have

-been constructed by hand, for the gratification of a few sages;

-but no artist, it is to be hoped, could have been found possessing

-the requisite ability and stupidity to execute the two portraits,

-or two groups, or two interiors, or two landscapes, identical in

-every minutia of the most elaborate detail, and yet differing

-in point of view by the inch between the two human eyes, by

-which the principle is brought to the level of any capacity.

-Here, therefore, the accuracy and insensibility of a machine

-could alone avail; and if in the order of things the cheap popular

-toy which the stereoscope now represents was necessary for

-the use of man, the photograph was first necessary for the service

-of the stereoscope.&mdash;<i>Quarterly Review</i>, No. 202.</p>

-

-<h3>THE STEREOSCOPE SIMPLIFIED.</h3>

-

-<p>When we look at any round object, first with one eye, and

-then with the other, we discover that with the right eye we

-see most of the right-hand side of the object, and with the left

-eye most of the left-hand side. These two images are combined,

-and we see an object which we know to be round.</p>

-

-<p>This is illustrated by the <i>Stereoscope</i>, which consists of two

-mirrors placed each at an angle of 45 deg., or of two semi-lenses

-turned with their curved sides towards each other. To view

-its phenomena two pictures are obtained by the camera on photographic

-paper of any object in two positions, corresponding

-with the conditions of viewing it with the two eyes. By the

-mirrors on the lenses these dissimilar pictures are combined

-within the eye, and the vision of an actually solid object is

-produced from the pictures represented on a plane surface.

-Hence the name of the instrument, which signifies <i>Solid I see</i>.&mdash;<i>Hunt’s

-Poetry of Science.</i></p>

-

-<h3>PHOTO-GALVANIC ENGRAVING.</h3>

-

-<p>That which was the chief aid of Niepce in the humblest

-dawn of the art, viz. to transform the photographic plate into<span class="pagenum"><a name="Page_48" id="Page_48">48</a></span>

-a surface capable of being printed, is in the above process

-done by the coöperation of Electricity with Photography. This

-invention of M. Pretsch, of Vienna, differs from all other

-attempts for the same purpose in not operating upon the photographic

-tablet itself, and by discarding the usual means of

-varnishes and bitings-in. The process is simply this: A glass

-tablet is coated with gelatine diluted till it forms a jelly, and

-containing bi-chromate of potash, nitrate of silver, and iodide

-of potassium. Upon this, when dry, is placed face downwards

-a paper positive, through which the light, being allowed to

-fall, leaves upon the gelatine a representation of the print. It

-is then soaked in water; and while the parts acted upon by the

-light are comparatively unaffected by the fluid, the remainder

-of the jelly swells, and rising above the general surface, gives

-a picture in relief, resembling an ordinary engraving upon

-wood. Of this intaglio a cast is now taken in gutta-percha,

-to which the electro process in copper being applied, a plate

-or matrix is produced, bearing on it an exact repetition of

-the original positive picture. All that now remains to be done

-is to repeat the electro process; and the result is a copper-plate

-in the necessary relievo, of which it has been said nature furnished

-the materials and science the artist, the inferior workman

-being only needed to roll it through the press.&mdash;<i>Quarterly

-Review</i>, No. 202.</p>

-

-<h3>SCIENCE OF THE SOAP-BUBBLE.</h3>

-

-<p>Few of the minor ingenuities of mankind have amused so

-many individuals as the blowing of bubbles with soap-lather

-from the bowl of a tobacco-pipe; yet how few who in childhood’s

-careless hours have thus amused themselves, have in

-after-life become acquainted with the beautiful phenomena of

-light which the soap-bubble will enable us to illustrate!</p>

-

-<p>Usually the bubble is formed within the bowl of a tobacco-pipe,

-and so inflated by blowing through the stem. It is also

-produced by introducing a capillary tube under the surface of

-soapy water, and so raising a bubble, which may be inflated to

-any convenient size. It is then guarded with a glass cover, to

-prevent its bursting by currents of air, evaporation, and other

-causes.</p>

-

-<p>When the bubble is first blown, its form is elliptical, into

-which it is drawn by its gravity being resisted; but the instant

-it is detached from the pipe, and allowed to float in air, it becomes

-a perfect sphere, since the air within presses equally in

-all directions. There is also a strong cohesive attraction in

-the particles of soap and water, after having been forcibly distended;

-and as a sphere or globe possesses less surface than

-any other figure of equal capacity, it is of all forms the best<span class="pagenum"><a name="Page_49" id="Page_49">49</a></span>

-adapted to the closest approximation of the particles of soap

-and water, which is another reason why the bubble is globular.

-The film of which the bubble consists is inconceivably thin

-(not exceeding the two-millionth part of an inch); and by the

-evaporation from its surface, the contraction and expansion of

-the air within, and the tendency of the soap-lather to gravitate

-towards the lower part of the bubble, and consequently to render

-the upper part still thinner, it follows that the bubble lasts

-but a few seconds. If, however, it were blown in a glass vessel,

-and the latter immediately closed, it might remain for some

-time; Dr. Paris thus preserved a bubble for a considerable period.</p>

-

-<p>Dr. Hooke, by means of the coloured rings upon the soap-bubble,

-studied the curious subject of the colours of thin plates,

-and its application to explain the colours of natural bodies.

-Various phenomena were also discovered by Newton, who thus

-did not disdain to make a soap-bubble the object of his study.

-The colours which are reflected from the upper surface of the

-bubble are caused by the decomposition of the light which falls

-upon it; and the range of the phenomena is alike extensive and

-beautiful.<a name="FNanchor_15" id="FNanchor_15" href="#Footnote_15" class="fnanchor">15</a></p>

-

-<p>Newton (says Sir D. Brewster), having covered the soap-bubble

-with a glass shade, saw its colours emerge in regular

-order, like so many concentric rings encompassing the top of

-it. As the bubble grew thinner by the continual subsidence

-of the water, the rings dilated slowly, and overspread the whole

-of it, descending to the bottom, where they vanished successively.

-When the colours had all emerged from the top, there

-arose in the centre of the rings a small round black spot, dilating

-it to more than half an inch in breadth till the bubble

-burst. Upon examining the rings between the object-glasses,

-Newton found that when they were only <i>eight</i> or <i>nine</i> in number,

-more than <i>forty</i> could be seen by viewing them through a

-prism; and even when the plate of air seemed all over uniformly

-white, multitudes of rings were disclosed by the prism.

-By means of these observations Newton was enabled to form

-his <i>Scale of Colours</i>, of great value in all optical researches.</p>

-

-<p>Dr. Reade has thus produced a permanent soap-bubble:</p>

-

-<blockquote>

-

-<p>Put into a six-ounce phial two ounces of distilled water, and set

-the phial in a vessel of water boiling on the fire. The water in the

-phial will soon boil, and steam will issue from its mouth, expelling the

-whole of the atmospheric air from within. Then throw in a piece of

-soap about the size of a small pea, cork the phial, and at the same instant<span class="pagenum"><a name="Page_50" id="Page_50">50</a></span>

-remove it and the vessel from the fire. Then press the cork farther

-into the neck of the phial, and cover it thickly with sealing-wax;

-and when the contents are cold, a perfect vacuum will be formed within

-the bottle,&mdash;much better, indeed, than can be produced by the best-constructed

-air-pump.</p>

-

-<p>To form a bubble, hold the bottle horizontally in both hands, and

-give it a sudden upward motion, which will throw the liquid into a wave,

-whose crest touching the upper interior surface of the phial, the tenacity

-of the liquid will cause a film to be retained all round the phial. Next

-place the phial on its bottom; when the film will form a section of the

-cylinder, being nearly but never quite horizontal. The film will be now

-colourless, since it reflects all the light which falls upon it. By remaining

-at rest for a minute or two, minute currents of lather will descend

-by their gravitating force down the inclined plane formed by the

-film, the upper part of which thus becomes drained to the necessary

-thinness; and this is the part to be observed.</p></blockquote>

-

-<p>Several concentric segments of coloured rings are produced;

-the colours, beginning from the top, being as follows:</p>

-

-<p class="in0 in4">

-<i>1st order</i>: Black, white, yellow, orange, red.<br />

-<i>2d order</i>: Purple, blue, white, yellow, red.<br />

-<i>3d order</i>: Purple, blue, green, yellowish-green, white, red.<br />

-<i>4th order</i>: Purple, blue, green, white, red.<br />

-<i>5th order</i>: Greenish-blue, very pale red.<br />

-<i>6th order</i>: Greenish-blue, pink.<br />

-<i>7th order</i>: Greenish-blue, pink.

-</p>

-

-<p class="in0">As the segments advance they get broader, while the film becomes

-thinner and thinner. The several orders disappear upwards

-as the film becomes too thin to reflect their colours,

-until the first order alone remains, occupying the whole surface

-of the film. Of this order the red disappears first, then the

-orange, and lastly the yellow. The film is now divided by a

-line into two nearly equal portions, one black and the other

-white. This remains for some time; at length the film becomes

-too thin to hold together, and then vanishes. The colours are

-not faint and imperfect, but well defined, glowing with gorgeous

-hues, or melting into tints so exquisite as to have no

-rival through the whole circle of the arts. We quote these details

-from Mr. Tomlinson’s excellent <i>Student’s Manual of Natural

-Philosophy</i>.</p>

-

-<blockquote>

-

-<p>We find the following anecdote related of Newton at the above

-period. When Sir Isaac changed his residence, and went to live in

-St. Martin’s Street, Leicester Square, his next-door neighbour was a

-widow lady, who was much puzzled by the little she observed of the

-habits of the philosopher. A Fellow of the Royal Society called upon

-her one day, when, among her domestic news, she mentioned that some

-one had come to reside in the adjoining house who, she felt certain, was

-a poor crazy gentleman, “because,” she continued, “he diverts himself

-in the oddest way imaginable. Every morning, when the sun shines so

-brightly that we are obliged to draw the window-blinds, he takes his

-seat on a little stool before a tub of soapsuds, and occupies himself for

-hours blowing soap-bubbles through a common clay-pipe, which bubbles<span class="pagenum"><a name="Page_51" id="Page_51">51</a></span>

-he intently watches floating about till they burst. He is doubtless,” she

-added, “now at his favourite amusement, for it is a fine day; do come

-and look at him.” The gentleman smiled, and they went upstairs;

-when, after looking through the staircase-window into the adjoining

-court-yard, he turned and said: “My dear madam, the person whom

-you suppose to be a poor lunatic is no other than the great Sir Isaac

-Newton studying the refraction of light upon thin plates; a phenomenon

-which is beautifully exhibited on the surface of a common soap-bubble.”</p></blockquote>

-

-<h3>LIGHT FROM QUARTZ.</h3>

-

-<p>Among natural phenomena (says Sir David Brewster) illustrative

-of the colours of thin plates, we find none more remarkable

-than one exhibited by the fracture of a large crystal of

-quartz of a smoky colour, and about two and a quarter inches

-in diameter. The surface of fracture, in place of being a face

-or cleavage, or irregularly conchoidal, as we have sometimes

-seen it, was filamentous, like a surface of velvet, and consisted

-of short fibres, so small as to be incapable of reflecting light.

-Their size could not have been greater than the third of the

-millionth part of an inch, or one-fourth of the thinnest part of

-the soap-bubble when it exhibits the black spot where it bursts.</p>

-

-<h3>CAN THE CAT SEE IN THE DARK?</h3>

-

-<p>No, in all probability, says the reader; but the opposite

-popular belief is supported by eminent naturalists.</p>

-

-<blockquote>

-

-<p>Buffon says: “The eyes of the cat shine in the dark somewhat like

-diamonds, which throw out during the night the light with which they

-were in a manner impregnated during the day.”</p>

-

-<p>Valmont de Bamare says: “The pupil of the cat is during the night

-still deeply imbued with the light of the day;” and again, “the eyes of

-the cat are during the night so imbued with light that they then appear

-very shining and luminous.”</p>

-

-<p>Spallanzani says: “The eyes of cats, polecats, and several other animals,

-shine in the dark like two small tapers;” and he adds that this

-light is phosphoric.</p>

-

-<p>Treviranus says: “The eyes of the cat <i>shine where no rays of light

-penetrate</i>; and the light must in many, if not in all, cases proceed from

-the eye itself.”</p></blockquote>

-

-<p>Now, that the eyes of the cat do shine in the dark is to a

-certain extent true: but we have to inquire whether by <i>dark</i>

-is meant the entire absence of light; and it will be found that

-the solution of this question will dispose of several assertions

-and theories which have for centuries perplexed the subject.</p>

-

-<p>Dr. Karl Ludwig Esser has published in Karsten’s Archives

-the results of an experimental inquiry on the luminous appearance

-of the eyes of the cat and other animals, carefully distinguishing

-such as evolve light from those which only reflect it.

-Having brought a cat into a half-darkened room, he observed

-from a certain direction that the cat’s eyes, when <i>opposite the<span class="pagenum"><a name="Page_52" id="Page_52">52</a></span>

-window</i>, sparkled brilliantly; but in other positions the light

-suddenly vanished. On causing the cat to be held so as to exhibit

-the light, and then gradually darkening the room, the

-light disappeared by the time the room was made quite dark.</p>

-

-<p>In another experiment, a cat was placed opposite the window

-in a darkened room. A few rays were permitted to enter,

-and by adjusting the light, one or both of the cat’s eyes were

-made to shine. In proportion as the pupil was dilated, the eyes

-were brilliant. By suddenly admitting a strong glare of light

-into the room, the pupil contracted; and then suddenly darkening

-the room, the eye exhibited a small round luminous point,

-which enlarged as the pupil dilated.</p>

-

-<p>The eyes of the cat sparkle most when the animal is in a

-lurking position, or in a state of irritation. Indeed, the eyes

-of all animals, as well as of man, appear brighter when in rage

-than in a quiescent state, which Collins has commemorated in

-his Ode on the Passions:</p>

-

-<div class="poem-container">

-<div class="poem"><div class="stanza">

-<span class="iq">“Next Anger rushed, his eyes on fire.”<br /></span>

-</div></div>

-</div>

-

-<p class="in0">This brilliancy is said to arise from an increased secretion of the

-lachrymal fluid on the surface of the eye, by which the reflection

-of the light is increased. Dr. Esser, in places absolutely

-dark, never discovered the slightest trace of light in the eye

-of the cat; and he has no doubt that in all cases where cats’

-eyes have been seen to shine in dark places, such as a cellar,

-light penetrated through some window or aperture, and fell

-upon the eyes of the animal as it turned towards the opening,

-while the observer was favourably situated to obtain a view of

-the reflection.</p>

-

-<p>To prove more clearly that this light does not depend upon

-the will of the animal, nor upon its angry passions, experiments

-were made upon the head of a dead cat. The sun’s rays were

-admitted through a small aperture; and falling immediately

-upon the eyes, caused them to glow with a beautiful green light

-more vivid even than in the case of a living animal, on account

-of the increased dilatation of the pupil. It was also remarked

-that black and fox-coloured cats gave a brighter light than

-gray and white cats.</p>

-

-<p>To ascertain the cause of this luminous appearance Dr. Esser

-dissected the eyes of cats, and exposed them to a small regulated

-amount of light after having removed different portions.

-The light was not diminished by the removal of the

-cornea, but only changed in colour. The light still continued

-after the iris was displaced; but on taking away the crystalline

-lens it greatly diminished both in intensity and colour. Dr.

-Esser then conjectured that the tapetum in the hinder part of

-the eye must form a spot which caused the reflection of the<span class="pagenum"><a name="Page_53" id="Page_53">53</a></span>

-incident rays of light, and thus produce the shining; and this

-appeared more probable as the light of the eye now seemed to

-emanate from a single spot. Having taken away the vitreous

-humour, Dr. Esser observed that the entire want of the pigment

-in the hinder part of the choroid coat, where the optic nerve

-enters, formed a greenish, silver-coloured, changeable oblong

-spot, which was not symmetrical, but surrounded the optic

-nerve so that the greater part was above and only the smaller

-part below it; wherefore the greater part lay beyond the axis

-of vision. It is this spot, therefore, that produces the reflection

-of the incident rays of light, and beyond all doubt, according

-to its tint, contributes to the different colouring of the light.</p>

-

-<p>It may be as well to explain that the interior of the eye is

-coated with a black pigment, which has the same effect as the

-black colour given to the inner surface of optical instruments:

-it absorbs any rays of light that may be reflected within the eye,

-and prevents them from being thrown again upon the retina

-so as to interfere with the distinctness of the images formed

-upon it. The retina is very transparent; and if the surface behind

-it, instead of being of a dark colour, were capable of reflecting

-light, the luminous rays which had already acted on

-the retina would be reflected back again through it, and not

-only dazzle from excess of light, but also confuse and render

-indistinct the images formed on the retina. Now in the case

-of the cat this black pigment, or a portion of it, is wanting; and

-those parts of the eye from which it is absent, having either a

-white or a metallic lustre, are called the tapetum. The smallest

-portion of light entering from it is reflected as by a concave

-mirror; and hence it is that the eyes of animals provided with

-this structure are luminous in a very faint light.</p>

-

-<p>These experiments and observations show that the shining

-of the eyes of the cat does not arise from a phosphoric light,

-but only from a reflected light; that consequently it is not an

-effect of the will of the animal, or of violent passions; that

-their shining does not appear in absolute darkness; and that

-it cannot enable the animal to move securely in the dark.</p>

-

-<p>It has been proved by experiment that there exists a set of

-rays of light of far higher refrangibility than those seen in the

-ordinary Newtonian spectrum. Mr. Hunt considers it probable

-that these highly refrangible rays, although under ordinary

-circumstances invisible to the human eye, may be adapted to

-produce the necessary degree of excitement upon which vision

-depends in the optic nerves of the night-roaming animals. The

-bat, the owl, and the cat may see in the gloom of the night

-by the aid of rays which are invisible to, or inactive on, the

-eyes of man or those animals which require the light of day

-for perfect vision.</p>

-

-<hr />

-

-<p><span class="pagenum"><a name="Page_54" id="Page_54">54</a></span></p>

-

-<div class="chapter"></div>

-<h2><a name="Astronomy" id="Astronomy"></a>Astronomy.</h2>

-

-<h3>THE GREAT TRUTHS OF ASTRONOMY.</h3>

-

-<p>The difficulty of understanding these marvellous truths has

-been glanced at by an old divine (see <i>Things not generally

-Known</i>, p. 1); but the rarity of their full comprehension by

-those unskilled in mathematical science is more powerfully

-urged by Lord Brougham in these cogent terms:</p>

-

-<blockquote>

-

-<p>Satisfying himself of the laws which regulate the mutual actions of

-the planetary bodies, the mathematician can convince himself of a truth

-yet more sublime than Newton’s discovery of gravitation, though flowing

-from it; and must yield his assent to the marvellous position, that

-all the irregularities occasioned in the system of the universe by the

-mutual attraction of its members are periodical, and subject to an eternal

-law, which prevents them from ever exceeding a stated amount, and

-secures through all time the balanced structure of a universe composed

-of bodies whose mighty bulk and prodigious swiftness of motion mock

-the utmost efforts of the human imagination. All these truths are to

-the skilful mathematician as thoroughly known, and their evidence is as

-clear, as the simplest proposition of arithmetic to common understandings.

-But how few are those who thus know and comprehend them!

-Of all the millions that thoroughly believe these truths, certainly not a

-thousand individuals are capable of following even any considerable portion

-of the demonstrations upon which they rest; and probably not a

-hundred now living have ever gone through the whole steps of these

-demonstrations.&mdash;<i>Dissertations on Subjects of Science connected with

-Natural Theology</i>, vol. ii.</p></blockquote>

-

-<p>Sir David Brewster thus impressively illustrates the same

-subject:</p>

-

-<blockquote>

-

-<p>Minds fitted and prepared for this species of inquiry are capable of

-appreciating the great variety of evidence by which the truths of the

-planetary system are established; but thousands of individuals, and

-many who are highly distinguished in other branches of knowledge, are

-incapable of understanding such researches, and view with a sceptical

-eye the great and irrefragable truths of astronomy.</p>

-

-<p>That the sun is stationary in the centre of our system; that the earth

-moves round the sun, and round its own axis; that the diameter of

-the earth is 8000 miles, and that of the sun <i>one hundred and ten times

-as great</i>; that the earth’s orbit is 190,000,000 of miles in breadth; and

-that if this immense space were filled with light, it would appear only

-like a luminous point at the nearest fixed star,&mdash;are positions absolutely

-unintelligible and incredible to all who have not carefully studied the

-subject. To millions of our species, then, the great Book of Nature is

-absolutely sealed; though it is in the power of all to unfold its pages, and

-to peruse those glowing passages which proclaim the power and wisdom

-of its Author.</p></blockquote>

-

-<p><span class="pagenum"><a name="Page_55" id="Page_55">55</a></span></p>

-

-<h3>ASTRONOMY AND DATES ON MONUMENTS.</h3>

-

-<p>Astronomy is a useful aid in discovering the Dates of ancient

-Monuments. Thus, on the ceiling of a portico among the ruins

-of Tentyris are the twelve signs of the Zodiac, placed according

-to the apparent motion of the sun. According to this Zodiac,

-the summer solstice is in Leo; from which it is easy to compute,

-by the precession of the equinoxes of 50″·1 annually, that

-the Zodiac of Tentyris must have been made 4000 years ago.</p>

-

-<p>Mrs. Somerville relates that she once witnessed the ascertainment

-of the date of a Papyrus by means of astronomy. The

-manuscript was found in Egypt, in a mummy-case; and its antiquity

-was determined by the configuration of the heavens at

-the time of its construction. It proved to be a horoscope of the

-time of Ptolemy.</p>

-

-<h3>“THE CRYSTAL VAULT OF HEAVEN.”</h3>

-

-<p>This poetic designation dates back as far as the early period

-of Anaximenes; but the first clearly defined signification of the

-idea on which the term is based occurs in Empedocles. This

-philosopher regarded the heaven of the fixed stars as a solid

-mass, formed from the ether which had been rendered crystalline

-by the action of fire.</p>

-

-<p>In the Middle Ages, the fathers of the Church believed the

-firmament to consist of from seven to ten glassy strata, incasing

-each other like the different coatings of an onion. This

-supposition still keeps its ground in some of the monasteries of

-southern Europe, where Humboldt was greatly surprised to

-hear a venerable prelate express an opinion in reference to the

-fall of aerolites at Aigle, that the bodies we called meteoric

-stones with vitrified crusts were not portions of the fallen stone

-itself, but simply fragments of the crystal vault shattered by it

-in its fall.</p>

-

-<p>Empedocles maintained that the fixed stars were riveted to

-the crystal heavens; but that the planets were free and unconstrained.

-It is difficult to conceive how, according to Plato in

-the <i>Timæus</i>, the fixed stars, riveted as they are to solid spheres,

-could rotate independently.</p>

-

-<p>Among the ancient views, it may be mentioned that the

-equal distance at which the stars remained, while the whole vault

-of heaven seemed to move from east to west, had led to the

-idea of a firmament and a solid crystal sphere, in which Anaximenes

-(who was probably not much later than Pythagoras)

-had conjectured that the stars were riveted like nails.</p>

-

-<h3>MUSIC OF THE SPHERES.</h3>

-

-<p>The Pythagoreans, in applying their theory of numbers to<span class="pagenum"><a name="Page_56" id="Page_56">56</a></span>

-the geometrical consideration of the five regular bodies, to the

-musical intervals of tone which determine a word and form

-different kinds of sounds, extended it even to the system of

-the universe itself; supposing that the moving, and, as it were,

-vibrating planets, exciting sound-waves, must produce a <i>spheral

-music</i>, according to the harmonic relations of their intervals of

-space. “This music,” they add, “would be perceived by the

-human ear, if it was not rendered insensible by extreme familiarity,

-as it is perpetual, and men are accustomed to it from

-childhood.”</p>

-

-<blockquote>

-

-<p>The Pythagoreans affirm, in order to justify the reality of the tones

-produced by the revolution of the spheres, that hearing takes place only

-where there is an alternation of sound and silence. The inaudibility of

-the spheral music is also accounted for by its overpowering the senses.

-Aristotle himself calls the Pythagorean tone-myth pleasing and ingenious,

-but untrue.</p></blockquote>

-

-<p>Plato attempted to illustrate the tones of the universe in an

-agreeable picture, by attributing to each of the planetary spheres

-a syren, who, supported by the stern daughters of Necessity,

-the three Fates, maintain the eternal revolution of the world’s

-axis. Mention is constantly made of the harmony of the

-spheres, though generally reproachfully, throughout the writings

-of Christian antiquity and the Middle Ages, from Basil the

-Great to Thomas Aquinas and Petrus Alliacus.</p>

-

-<p>At the close of the sixteenth century, Kepler revived these

-musical ideas, and sought to trace out the analogies between

-the relations of tone and the distances of the planets; and Tycho

-Brahe was of opinion that the revolving conical bodies were

-capable of vibrating the celestial air (what we now call “resisting

-medium”) so as to produce tones. Yet Kepler, although he

-had talked of Venus and the Earth sounding sharp in aphelion

-and flat in perihelion, and the highest tone of Jupiter and that

-of Venus coinciding in flat accord, positively declared there

-to be “no such things as sounds among the heavenly bodies,

-nor is their motion so turbulent as to elicit noise from the attrition

-of the celestial air.” (See <i>Things not generally Known</i>, p. 44.)</p>

-

-<h3>“MORE WORLDS THAN ONE.”</h3>

-

-<p>Although this opinion was maintained incidentally by various

-writers both on astronomy<a name="FNanchor_16" id="FNanchor_16" href="#Footnote_16" class="fnanchor">16</a> and natural religion, yet M.<span class="pagenum"><a name="Page_57" id="Page_57">57</a></span>

-Fontenelle was the first individual who wrote a treatise on the

-<i>Plurality of Worlds</i>, which appeared in 1685, the year before the

-publication of Newton’s <i>Principia</i>. Fontenelle’s work consists

-of five chapters: 1. The earth is a planet which turns round

-its axis, and also round the sun. 2. The moon is a habitable

-world. 3. Particulars concerning the world in the moon, and

-that the other planets are also inhabited. 4. Particulars of the

-worlds of Venus, Mercury, Mars, Jupiter, and Saturn. 5. The

-fixed stars are as many suns, each of which illuminates a world.

-In a future edition, 1719, Fontenelle added, 6. New thoughts

-which confirm those in the preceding conversations, and the

-latest discoveries which have been made in the heavens. The

-next work on the subject was the <i>Theory of the Universe, or

-Conjectures concerning the Celestial Bodies and their Inhabitants</i>,

-1698, by Christian Huygens, the contemporary of Newton.</p>

-

-<p>The doctrine is maintained by almost all the distinguished

-astronomers and writers who have flourished since the true

-figure of the earth was determined. Giordano Bruna of Nola,

-Kepler, and Tycho Brahe, believed in it; and Cardinal Cusa

-and Bruno, before the discovery of binary systems among the

-stars, believed also that the stars were inhabited. Sir Isaac

-Newton likewise adopted the belief; and Dr. Bentley, Master

-of Trinity College, Cambridge, in his eighth sermon on the Confutation

-of Atheism from the origin and frame of the world,

-has ably maintained the same doctrine. In our own day we

-may number among its supporters the distinguished names of

-the Marquis de la Place, Sir William and Sir John Herschel,

-Dr. Chalmers, Isaac Taylor, and M. Arago. Dr. Chalmers maintains

-the doctrine in his <i>Astronomical Discourses</i>, which one

-Alexander Maxwell (who did not believe in the grand truths of

-astronomy) attempted to controvert, in 1820, in a chapter of a

-volume entitled <i>Plurality of Worlds</i>.</p>

-

-<p>Next appeared <i>Of a Plurality of Worlds</i>, attributed to the

-Rev. Dr. Whewell, Master of Trinity College, Cambridge; urging

-the theological not less than the scientific reasons for believing

-in the old tradition of a single world, and maintaining that “the

-earth is really the largest planetary body in the solar system,&mdash;its

-domestic hearth, and the only world in the universe.” “I

-do not pretend,” says Dr. Whewell, “to disprove the plurality of

-worlds; but I ask in vain for any argument which makes the

-doctrine probable.” “It is too remote from knowledge to be

-either proved or disproved.” Sir David Brewster has replied

-to Dr. Whewell’s Essay, in <i>More Worlds than One, the Creed

-of the Philosopher and the Hope of the Christian</i>, emphatically

-maintaining that analogy strongly countenances the idea of all

-the solar planets, if not all worlds in the universe, being peopled

-with creatures not dissimilar in being and nature to the<span class="pagenum"><a name="Page_58" id="Page_58">58</a></span>

-inhabitants of the earth. This view is supported in <i>Scientific

-Certainties of Planetary Life</i>, by T.&nbsp;C. Simon, who well treats one

-point of the argument&mdash;that mere distance of the planets from

-the central sun does not determine the condition as to light

-and heat, but that the density of the ethereal medium enters

-largely into the calculation. Mr. Simon’s general conclusion is,

-that “neither on account of deficient or excessive heat, nor with

-regard to the density of the materials, nor with regard to the force

-of gravity on the surface, is there the slightest pretext for supposing

-that all the planets of our system are not inhabited by

-intellectual creatures with animal bodies like ourselves,&mdash;moral

-beings, who know and love their great Maker, and who wait,

-like the rest of His creation, upon His providence and upon His

-care.” One of the leading points of Dr. Whewell’s Essay is, that

-we should not elevate the conjectures of analogy into the rank

-of scientific certainties; and that “the force of all the presumptions

-drawn from physical reasoning for the opinion of planets

-and stars being either inhabited or uninhabited is so small, that

-the belief of all thoughtful persons on this subject will be determined

-by moral, metaphysical, and theological considerations.”</p>

-

-<h3>WORLDS TO COME&mdash;ABODES OF THE BLEST.</h3>

-

-<p>Sir David Brewster, in his eloquent advocacy of the doctrine

-of “more worlds than one,” thus argues for their peopling:</p>

-

-<blockquote>

-

-<p>Man, in his future state of existence, is to consist, as at present,

-of a spiritual nature residing in a corporeal frame. He must live, therefore,

-upon a material planet, subject to all the laws of matter, and performing

-functions for which a material body is indispensable. We must

-consequently find for the race of Adam, if not races that may have

-preceded him, a material home upon which they may reside, or by

-which they may travel, by means unknown to us, to other localities in

-the universe. At the present hour, the inhabitants of the earth are nearly

-<i>a thousand millions</i>; and by whatever process we may compute the

-numbers that have existed before the present generation, and estimate

-those that are yet to inherit the earth, we shall obtain a population

-which the habitable parts of our globe could not possibly accommodate.

-If there is not room, then, on our earth for the millions of millions

-of beings who have lived and died upon its surface, and who may yet

-live and die during the period fixed for its occupation by man, we can

-scarcely doubt that their future abode must be on some of the primary

-or secondary planets of the solar system, whose inhabitants have ceased

-to exist like those on the earth, or upon planets in our own or in other

-systems which have been in a state of preparation, as our earth was,

-for the advent of intellectual life.</p></blockquote>

-

-<h3>“GAUGING THE HEAVENS.”</h3>

-

-<p>Sir William Herschel, in 1785, conceived the happy idea

-of counting the number of stars which passed at different<span class="pagenum"><a name="Page_59" id="Page_59">59</a></span>

-heights and in various directions over the field of view, of fifteen

-minutes in diameter, of his twenty-feet reflecting telescope.

-The field of view each time embraced only 1/833000th of

-the whole heavens; and it would therefore require, according

-to Struve, eighty-three years to gauge the whole sphere by a

-similar process.</p>

-

-<h3>VELOCITY OF THE SOLAR SYSTEM.</h3>

-

-<p>M. F. W. G. Struve gives as the splendid result of the

-united studies of MM. Argelander, O. Struve, and Peters,

-grounded on observations made at the three Russian observatories

-of Dorpat, Abo, and Pulkowa, “that the velocity of the

-motion of the solar system in space is such that the sun, with

-all the bodies which depend upon it, advances annually towards

-the constellation Hercules<a name="FNanchor_17" id="FNanchor_17" href="#Footnote_17" class="fnanchor">17</a> 1·623 times the radius of the

-earth’s orbit, or 33,550,000 geographical miles. The possible

-error of this last number amounts to 1,733,000 geographical

-miles, or to a <i>seventh</i> of the whole value. We may, then, wager

-400,000 to 1 that the sun has a proper progressive motion, and

-1 to 1 that it is comprised between the limits of thirty-eight

-and twenty-nine millions of geographical miles.”</p>

-

-<blockquote>

-

-<p>That is, taking 95,000,000 of English miles as the mean radius of

-the Earth’s orbit, we have 95 × 1·623 = 154·185 millions of miles; and

-consequently,</p>

-

-<table summary="Velocity of the Solar System">

-  <tr>

-    <td> </td>

-    <td class="tdl" colspan="2">English Miles.</td></tr>

-  <tr>

-    <td class="tdc">The velocity of the Solar System</td>

-    <td class="tdr lrpad">154,185,000</td>

-    <td class="tdl">in the year.</td></tr>

-  <tr>

-    <td class="tdc">”<span class="in4">”</span></td>

-    <td class="tdr lrpad">422,424</td>

-    <td class="tdl">in a day.</td></tr>

-  <tr>

-    <td class="tdc">”<span class="in4">”</span></td>

-    <td class="tdr lrpad">17,601</td>

-    <td class="tdl">in an hour.</td></tr>

-  <tr>

-    <td class="tdc">”<span class="in4">”</span></td>

-    <td class="tdr lrpad">293</td>

-    <td class="tdl">in a minute.</td></tr>

-  <tr>

-    <td class="tdc">”<span class="in4">”</span></td>

-    <td class="tdr lrpad">57</td>

-    <td class="tdl">in a second.</td></tr>

-</table>

-

-<p class="in0">The Sun and all his planets, primary and secondary, are therefore now

-in rapid motion round an invisible focus. To that now dark and mysterious

-centre, from which no ray, however feeble, shines, we may in

-another age point our telescopes, detecting perchance the great luminary

-which controls our system and bounds its path: into that vast

-orbit man, during the whole cycle of his race, may never be allowed to

-round.&mdash;<i>North-British Review</i>, No. 16.</p></blockquote>

-

-<h3>NATURE OF THE SUN.</h3>

-

-<p>M. Arago has found, by experiments with the polariscope,

-that the light of gaseous bodies is natural light when it issues

-from the burning surface; although this circumstance does not

-prevent its subsequent complete polarisation, if subjected to<span class="pagenum"><a name="Page_60" id="Page_60">60</a></span>

-suitable reflections or refractions. Hence we obtain <i>a most

-simple method of discovering the nature of the sun</i> at a distance

-of forty millions of leagues. For if the light emanating from

-the margin of the sun, and radiating from the solar substance

-<i>at an acute angle</i>, reach us without having experienced any

-sensible reflections or refractions in its passage to the earth,

-and if it offer traces of polarisation, the sun must be <i>a solid or

-a liquid body</i>. But if, on the contrary, the light emanating

-from the sun’s margin give no indications of polarisation, the

-<i>incandescent</i> portion of the sun must be <i>gaseous</i>. It is by means

-of such a methodical sequence of observations that we may

-acquire exact ideas regarding the physical constitution of the

-sun.&mdash;<i>Note to Humboldt’s Cosmos</i>, vol. iii.</p>

-

-<h3>STRUCTURE OF THE LUMINOUS DISC OF THE SUN.</h3>

-

-<p>The extraordinary structure of the <i>fully luminous</i> Disc of

-the Sun, as seen through Sir James South’s great achromatic,

-in a drawing made by Mr. Gwilt, resembles compressed curd,

-or white almond-soap, or a mass of asbestos fibres, lying in

-a <i>quaquaversus</i> direction, and compressed into a solid mass.

-There can be no illusion in this phenomenon; it is seen by

-every person with good vision, and on every part of the sun’s

-luminous surface or envelope, which is thus shown to be not

-a <i>flame</i>, but a soft solid or thick fluid, maintained in an incandescent

-state by subjacent heat, capable of being disturbed by

-differences of temperature, and broken up as we see it when

-the sun is covered with spots or openings in the luminous

-matter.&mdash;<i>North-British Review</i>, No. 16.</p>

-

-<blockquote>

-

-<p>Copernicus named the sun the lantern of the world (<i>lucerna mundi</i>);

-and Theon of Smyrna called it the heart of the universe. The mass of

-the sun is, according to Encke’s calculation of Sabine’s pendulum formula,

-359,551 times that of the earth, or 355,499 times that of the earth

-and moon together; whence the density of the sun is only about ¼ (or

-more accurately 0·252) that of the earth. The volume of the sun is

-600 times greater, and its mass, according to Galle, 738 times greater,

-than that of all the planets combined. It may assist the mind in conceiving

-a sensuous image of the magnitude of the sun, if we remember

-that if the solar sphere were entirely hollowed out, and the earth placed

-in its centre, there would still be room enough for the moon to describe

-its orbit, even if the radius of the latter were increased 160,000 geographical

-miles. A railway-engine, moving at the rate of thirty miles

-an hour, would require 360 years to travel from the earth to the sun.

-The diameter of the sun is rather more than one hundred and eleven

-times the diameter of the earth. Therefore the volume or bulk of the

-sun must be nearly <i>one million four hundred thousand</i> times that of the

-earth. Lastly, if all the bodies composing the solar system were formed

-into one globe, it would be only about the five-hundredth part of the

-size of the sun.</p></blockquote>

-

-<p><span class="pagenum"><a name="Page_61" id="Page_61">61</a></span></p>

-

-<h3>GREAT SIZE OF THE SUN ON THE HORIZON EXPLAINED.</h3>

-

-<p>The dilated size (generally) of the Sun or Moon, when seen

-near the horizon, beyond what they appear to have when high

-up in the sky, has nothing to do with refraction. It is an illusion

-of the judgment, arising from the terrestrial objects interposed,

-or placed in close comparison with them. In that situation

-we view and judge of them as we do of terrestrial objects&mdash;in

-detail, and with an acquired attention to parts. Aloft we

-have no association to guide us, and their insulation in the

-expanse of the sky leads us rather to undervalue than to over-rate

-their apparent magnitudes. Actual measurement with a

-proper instrument corrects our error, without, however, dispelling

-our illusion. By this we learn that the sun, when just

-on the horizon, subtends at our eyes almost exactly the same,

-and the moon a materially <i>less</i>, angle than when seen at a

-greater altitude in the sky, owing to its greater distance from

-us in the former situation as compared with the latter.&mdash;<i>Sir

-John Herschel’s Outlines.</i></p>

-

-<h3>TRANSLATORY MOTION OF THE SUN.</h3>

-

-<p>This phenomenon is the progressive motion of the centre

-of gravity of the whole solar system in universal space. Its

-velocity, according to Bessel, is probably four millions of miles

-daily, in a <i>relative</i> velocity to that of 61 Cygni of at least

-3,336,000 miles, or more than double the velocity of the revolution

-of the earth in her orbit round the sun. This change of the

-entire solar system would remain unknown to us, if the admirable

-exactness of our astronomical instruments of measurement,

-and the advancement recently made in the art of observing,

-did not cause our progress towards remote stars to be

-perceptible, like an approximation to the objects of a distant

-shore in apparent motion. The proper motion of the star 61

-Cygni, for instance, is so considerable, that it has amounted

-to a whole degree in the course of 700 years.&mdash;<i>Humboldt’s Cosmos</i>,

-vol. i.</p>

-

-<h3>THE SUN’S LIGHT COMPARED WITH TERRESTRIAL LIGHTS.</h3>

-

-<p>Mr. Ponton has by means of a simple monochromatic photometer

-ascertained that a small surface, illuminated by mean

-solar light, is 444 times brighter than when it is illuminated by

-a moderator lamp, and 1560 times brighter than when it is

-illuminated by a wax-candle (short six in the lb.)&mdash;the artificial

-light being in both instances placed at two inches’ distance

-from the illuminated surface. And three electric lights, each<span class="pagenum"><a name="Page_62" id="Page_62">62</a></span>

-equal to 520 wax-candles, will render a small surface as bright

-as when it is illuminated by mean sunshine.</p>

-

-<p>It is thence inferred, that a stratum occupying the entire

-surface of the sphere of which the earth’s distance from the

-sun is the radius, and consisting of three layers of flame, each

-1/1000th of an inch in thickness, each possessing a brightness

-equal to that of such an electric light, and all three embraced

-within a thickness of 1/40th of an inch, would give an amount

-of illumination equal in quantity and intensity to that of the

-sun at the distance of 95 millions of miles from his centre.</p>

-

-<p>And were such a stratum transferred to the surface of the

-sun, where it would occupy 46,275 times less area, its thickness

-would be increased to 94 feet, and it would embrace

-138,825 layers of flame, equal in brightness to the electric light;

-but the same effect might be produced by a stratum about

-nine miles in thickness, embracing 72 millions of layers, each

-having only a brightness equal to that of a wax-candle.<a name="FNanchor_18" id="FNanchor_18" href="#Footnote_18" class="fnanchor">18</a></p>

-

-<h3>ACTINIC POWER OF THE SUN.</h3>

-

-<p>Mr. J. J. Waterston, in 1857, made at Bombay some experiments

-on the photographic power of the sun’s direct light,

-to obtain data in an inquiry as to the possibility of measuring

-the diameter of the sun to a very minute fraction of a second,

-by combining photography with the principle of the electric

-telegraph; the first to measure the element space, the latter

-the element time. The result is that about 1/20000th of a second

-is sufficient exposure to the direct light of the sun to

-obtain a distinct mark on a sensitive collodion plate, when

-developed by the usual processes; and the duration of the

-sun’s full action on any one point is about 1/9000th of a second.</p>

-

-<p>M. Schatt, a young painter of Berlin, after 1500 experiments,

-succeeded in establishing a scale of all the shades of

-black which the action of the sun produces on photographic

-paper; so that by comparing the shade obtained at any given

-moment on a certain paper with that indicated on the scale,

-the exact force of the sun’s light may be determined.</p>

-

-<h3>HEATING POWER OF THE SUN.</h3>

-

-<p>All moving power has its origin in the rays of the sun.

-While Stephenson’s iron tubular railway-bridge over the Menai

-Straits, 400 feet long, bends but half an inch under the heaviest

-pressure of a train, it will bend up an inch and a half

-from its usual horizontal line when the sun shines on it for<span class="pagenum"><a name="Page_63" id="Page_63">63</a></span>

-some hours. The Bunker-Hill monument, near Boston, U.S.,

-is higher in the evening than in the morning of a sunny day;

-the little sunbeams enter the pores of the stone like so many

-wedges, lifting it up.</p>

-

-<p>In winter, the Earth is nearer the Sun by about 1/30 than in

-summer; but the rays strike the northern hemisphere more

-obliquely in winter than the other half year.</p>

-

-<p>M. Pouillet has estimated, with singular ingenuity, from a

-series of observations made by himself, that the whole quantity

-of heat which the Earth receives annually from the Sun is

-such as would be sufficient to melt a stratum of ice covering

-the entire globe forty-six feet deep.</p>

-

-<p>By the action of the sun’s rays upon the earth, vegetables,

-animals, and man, are in their turn supported; the rays become

-likewise, as it were, a store of heat, and “the sources of

-those great deposits of dynamical efficiency which are laid up

-for human use in our coal strata” (<i>Herschel</i>).</p>

-

-<p>A remarkable instance of the power of the sun’s rays is recorded

-at Stonehouse Point, Devon, in the year 1828. To lay

-the foundation of a sea-wall the workmen had to descend in a

-diving-bell, which was fitted with convex glasses in the upper

-part, by which, on several occasions in clear weather, the sun’s

-rays were so concentrated as to burn the labourers’ clothes

-when opposed to the focal point, and this when the bell was

-twenty-five feet under the surface of the water!</p>

-

-<h3>CAUSE OF DARK COLOUR OF THE SKIN.</h3>

-

-<p>Darkness of complexion has been attributed to the sun’s

-power from the age of Solomon to this day,&mdash;“Look not upon

-me, because I am black, because the sun hath looked upon

-me:” and there cannot be a doubt that, to a certain degree,

-the opinion is well founded. The invisible rays in the solar

-beams, which change vegetable colour, and have been employed

-with such remarkable effect in the daguerreotype, act

-upon every substance on which they fall, producing mysterious

-and wonderful changes in their molecular state, man not

-excepted.&mdash;<i>Mrs. Somerville.</i></p>

-

-<h3>EXTREME SOLAR HEAT.</h3>

-

-<p>The fluctuation in the sun’s direct heating power amounts

-to 1/15th, which is too considerable a fraction of the whole intensity

-not to aggravate in a serious degree the sufferings of

-those who are exposed to it in thirsty deserts without shelter.

-The amount of these sufferings, in the interior of Australia for

-instance, are of the most frightful kind, and would seem far to

-exceed what have ever been undergone by travellers in the<span class="pagenum"><a name="Page_64" id="Page_64">64</a></span>

-northern deserts of Africa. Thus Captain Sturt, in his account

-of his Australian exploration, says: “The ground was almost

-a molten surface; and if a match accidentally fell upon it, it

-immediately ignited.” Sir John Herschel has observed the

-temperature of the surface soil in South Africa as high as 159°

-Fahrenheit. An ordinary lucifer-match does not ignite when

-simply pressed upon a smooth surface at 212°; but <i>in the act

-of withdrawing it</i> it takes fire, and the slightest friction upon

-such a surface of course ignites it.</p>

-

-<h3>HOW DR. WOLLASTON COMPARED THE LIGHT OF THE SUN AND

-THE FIXED STARS.</h3>

-

-<p>In order to compare the Light of the Sun with that of a

-Star, Dr. Wollaston took as an intermediate object of comparison

-the light of a candle reflected from a bulb about a quarter

-of an inch in diameter, filled with quicksilver; and seen by one

-eye through a lens of two inches focus, at the same time that

-the star on the sun’s image, <i>placed at a proper distance</i>, was

-viewed by the other eye through a telescope. The mean of

-various trials seemed to show that the light of Sirius is equal

-to that of the sun seen in a glass bulb 1/10th of an inch in diameter,

-at the distance of 210 feet; or that they are in the

-proportion of one to ten thousand millions: but as nearly one

-half of this light is lost by reflection, the real proportion between

-the light from Sirius and the sun is not greater than

-that of one to twenty thousand millions.</p>

-

-<h3>“THE SUN DARKENED.”</h3>

-

-<p>Humboldt selects the following example from historical

-records as to the occurrence of a sudden decrease in the light

-of the Sun:</p>

-

-<blockquote>

-

-<p><span class="smcap smaller">A.D.</span> 33, the year of the Crucifixion. “Now from the sixth hour

-there was darkness over all the land till the ninth hour” (<i>St. Matthew</i>

-xxvii. 45). According to <i>St. Luke</i> (xxiii. 45), “the sun was darkened.”

-In order to explain and corroborate these narrations, Eusebius brings

-forward an eclipse of the sun in the 202d Olympiad, which had been

-noticed by the chronicler Phlegon of Tralles (<i>Ideler</i>, <i>Handbuch der

-Mathem. Chronologie</i>, Bd. ii. p. 417). Wurn, however, has shown that

-the eclipse which occurred during this Olympiad, and was visible over

-the whole of Asia Minor, must have happened as early as the 24th of

-November 29 <span class="smcap smaller">A.D.</span> The day of the Crucifixion corresponded with the

-Jewish Passover (<i>Ideler</i>, Bd. i. pp. 515&ndash;520), on the 14th of the month

-Nisan, and the Passover was always celebrated at the time of the <i>full

-moon</i>. The sun cannot therefore have been darkened for three hours by

-the moon. The Jesuit Scheiner thinks the decrease in the light might

-be ascribed to the occurrence of large sun-spots.</p></blockquote>

-

-<h3>THE SUN AND TERRESTRIAL MAGNETISM.</h3>

-

-<p>The important influence exerted by the Sun’s body, as a<span class="pagenum"><a name="Page_65" id="Page_65">65</a></span>

-mass, upon Terrestrial Magnetism, is confirmed by Sabine in

-the ingenious observation, that the period at which the intensity

-of the magnetic force is greatest, and the direction of the

-needle most near to the vertical line, falls in both hemispheres

-between the months of October and February; that is to say,

-precisely at the time when the earth is nearest to the sun, and

-moves in its orbit with the greatest velocity.</p>

-

-<h3>IS THE HEAT OF THE SUN DECREASING?</h3>

-

-<p>The Heat of the Sun is dissipated and lost by radiation, and

-must be progressively diminished unless its thermal energy be

-supplied. According to the measurements of M. Pouillet, the

-quantity of heat given out by the sun in a year is equal to that

-which would be produced by the combustion of a stratum of

-coal seventeen miles in thickness; and if the sun’s capacity for

-heat be assumed equal to that of water, and the heat be supposed

-drawn uniformly from its entire mass, its temperature

-would thereby undergo a diminution of 20·4° Fahr. annually.

-On the other hand, there is a vast store of force in our system

-capable of conversion into heat. If, as is indicated by the

-small density of the sun, and by other circumstances, that

-body has not yet reached the condition of incompressibility,

-we have in the future approximation of its parts a fund of

-heat, probably quite large enough to supply the wants of the

-human family to the end of its sojourn here. It has been calculated

-that an amount of condensation which would diminish

-the diameter of the sun by only the ten-thousandth part, would

-suffice to restore the heat emitted in 2000 years.</p>

-

-<h3>UNIVERSAL SUN-DIAL.</h3>

-

-<p>Mr. Sharp, of Dublin, exhibited to the British Association

-in 1849 a Dial, consisting of a cylinder set to the day of the

-month, and then elevated to the latitude. A thin plane of

-metal, in the direction of its axis, is then turned by a milled

-head below it till the shadow is a minimum, when a dial on

-the top shows the hours by one hand, and the minutes by another,

-to the precision of about three minutes.</p>

-

-<h3>LENGTH OF DAYS AT THE POLES.</h3>

-

-<p>During the summer, in the northern hemisphere, places

-near the North Pole are in <i>continual sunlight</i>&mdash;the sun never

-sets to them; while during that time places near the South

-Pole never see the sun. When it is summer in the southern

-hemisphere, and the sun shines on the South Pole without

-setting, the North Pole is entirely deprived of his light. Indeed,

-at the Poles there is but <i>one day and one night</i>; for the<span class="pagenum"><a name="Page_66" id="Page_66">66</a></span>

-sun shines for six months together on one Pole, and the other

-six months on the other Pole.</p>

-

-<h3>HOW THE DISTANCE OF THE SUN IS ASCERTAINED BY THE

-YARD-MEASURE.</h3>

-

-<p>Professor Airy, in his <i>Six Lectures on Astronomy</i>, gives a

-masterly analysis of a problem of considerable intricacy, viz.

-the determination of the parallax of the sun, and consequently

-of his distance, by observations of the transit of Venus, the connecting

-link between measures upon the earth’s surface and the

-dimensions of our system. The further step of investigating

-the parallax, and consequently the distance of the fixed stars

-(where that is practicable), is also elucidated; and the author,

-with evident satisfaction, thus sums up the several steps:</p>

-

-<blockquote>

-

-<p>By means of a yard-measure, a base-line in a survey was measured;

-from this, by the triangulations and computations of a survey, an arc of

-meridian on the earth was measured; from this, with proper observations

-with the zenith sector, the surveys being also repeated on different

-parts of the earth, the earth’s form and dimensions were ascertained;

-from these, and a previous independent knowledge of the proportions of

-the distances of the earth and other planets from the sun, with observations

-of the transit of Venus, the sun’s distance is determined; and from

-this, with observations leading to the parallax of the stars, the distance

-of the stars is determined. And <i>every step in the process can be distinctly

-referred to its basis, that is, the yard-measure</i>.</p></blockquote>

-

-<h3>HOW THE TIDES ARE PRODUCED BY THE SUN AND MOON.</h3>

-

-<p>Each of these bodies excites, by its attraction upon the

-waters of the sea, two gigantic waves, which flow in the same

-direction round the world as the attracting bodies themselves

-apparently do. The two waves of the moon, on account of

-her greater nearness, are about 3½ times as large as those excited

-by the sun. One of these waves has its crest on the

-quarter of the earth’s surface which is turned towards the

-moon; the other is at the opposite side. Both these quarters

-possess the flow of the tide, while the regions which lie between

-have the ebb. Although in the open sea the height of

-the tide amounts to only about three feet, and only in certain

-narrow channels, where the moving water is squeezed together,

-rises to thirty feet, the might of the phenomenon is nevertheless

-manifest from the calculation of Bessel, according to

-which a quarter of the earth covered by the sea possesses during

-the flow of the tide about 25,000 cubic miles of water

-more than during the ebb; and that, therefore, such a mass of

-water must in 6¼ hours flow from one quarter of the earth to

-the other.&mdash;<i>Professor Helmholtz.</i></p>

-

-<p><span class="pagenum"><a name="Page_67" id="Page_67">67</a></span></p>

-

-<h3>SPOTS ON THE SUN.</h3>

-

-<p>Sir John Herschel describes these phenomena, when watched

-from day to day, or even from hour to hour, as appearing to enlarge

-or contract, to change their forms, and at length disappear

-altogether, or to break out anew in parts of the surface where

-none were before. Occasionally they break up or divide into

-two or more. The scale on which their movements takes place

-is immense. A single second of angular measure, as seen from

-the earth, corresponds on the sun’s disc to 461 miles; and a

-circle of this diameter (containing therefore nearly 167,000

-square miles) is the least space which can be distinctly discerned

-on the sun as a <i>visible area</i>. Spots have been observed,

-however, whose linear diameter has been upwards of 45,000

-miles; and even, if some records are to be trusted, of very much

-greater extent. That such a spot should close up in six weeks

-time (for they seldom last much longer), its borders must approach

-at the rate of more than 1000 miles a-day.</p>

-

-<p>The same astronomer saw at the Cape of Good Hope, on the

-29th March 1837, a solar spot occupying an area of near <i>five

-square minutes</i>, equal to 3,780,000,000 square miles. “The

-black centre of the spot of May 25th, 1837 (not the tenth part

-of the preceding one), would have allowed the globe of our

-earth to drop through it, leaving a thousand miles clear of

-contact on all sides of that tremendous gulf.” For such an

-amount of disturbance on the sun’s atmosphere, what reason

-can be assigned?</p>

-

-<p>The Rev. Mr. Dawes has invented a peculiar contrivance,

-by means of which he has been enabled to scrutinise, under

-high magnifying power, minute portions of the solar disc. He

-places a metallic screen, pierced with a very small hole, in the

-focus of the telescope, where the image of the sun is formed.

-A small portion only of the image is thus allowed to pass

-through, so that it may be examined by the eye-piece without

-inconveniencing the observer by heat or glare. By this arrangement,

-Mr. Dawes has observed peculiarities in the constitution

-of the sun’s surface which are discernible in no other

-way.</p>

-

-<p>Before these observations, the dark spots seen on the sun’s

-surface were supposed to be portions of the solid body of the

-sun, laid bare to our view by those immense fluctuations in

-the luminous regions of its atmosphere to which it appears to

-be subject. It now appears that these dark portions are only

-an additional and inferior stratum of a very feebly luminous

-or illuminated portion of the sun’s atmosphere. This again in

-its turn Mr. Dawes has frequently seen pierced with a smaller

-and usually much more rounded aperture, which would seem<span class="pagenum"><a name="Page_68" id="Page_68">68</a></span>

-at last to afford a view of the real solar surface of most intense

-blackness.</p>

-

-<p>M. Schwabe, of Dessau, has discovered that the abundance

-or paucity of spots displayed by the sun’s surface is subject to

-a law of periodicity. This has been confirmed by M. Wolf, of

-Berne, who shows that the period of these changes, from minimum

-to minimum, is 11 years and 11-hundredths of a year,

-being exactly at the rate of nine periods per century, the last

-year of each century being a year of minimum. It is strongly

-corroborative of the correctness both of M. Wolf’s period and

-also of the periodicity itself, that of all the instances of the

-appearance of spots on the sun recorded in history, even before

-the invention of the telescope, or of remarkable deficiencies in

-the sun’s light, of which there are great numbers, only two are

-found to deviate as much as two years from M. Wolf’s epochs.

-Sir William Herschel observed that the presence or absence of

-spots had an influence on the temperature of the seasons; his

-observations have been fully confirmed by M. Wolf. And, from

-an examination of the chronicles of Zurich from <span class="smcap smaller">A.D.</span> 1000 to

-<span class="smcap smaller">A.D.</span> 1800, he has come to the conclusion “that years rich in

-solar spots are in general drier and more fruitful than those of

-an opposite character; while the latter are wetter and more

-stormy than the former.”</p>

-

-<p>The most extraordinary fact, however, in connection with

-the spots on the sun’s surface, is the singular coincidence of

-their periods with those great disturbances in the magnetic

-system of the earth to which the epithet of “magnetic storms”

-has been affixed.</p>

-

-<blockquote>

-

-<p>These disturbances, during which the magnetic needle is greatly

-and universally agitated (not in a particular limited locality, but at one

-and the same instant of time over whole continents, or even over the

-whole earth), are found, so far as observation has hitherto extended,

-to maintain a parallel, both in respect of their frequency of occurrence

-and intensity in successive years, with the abundance and magnitude

-of the spots in the same years, too close to be regarded as fortuitous.

-The coincidence of the epochs of maxima and minima in the two series

-of phenomena amounts, indeed, to identity; a fact evidently of most

-important significance, but which neither astronomical nor magnetic

-science is yet sufficiently advanced to interpret.&mdash;<i>Herschel’s Outlines.</i></p></blockquote>

-

-<p>The signification and connection of the above varying phenomena

-(Humboldt maintains) can never be manifested in their

-entire importance until an uninterrupted series of representations

-of the sun’s spots can be obtained by the aid of mechanical

-clock-work and photographic apparatus, as the result

-of prolonged observations during the many months of serene

-weather enjoyed in a tropical climate.</p>

-

-<blockquote>

-

-<p>M. Schwabe has thus distinguished himself as an indefatigable observer

-of the sun’s spots, for his researches received the Royal Astronomical<span class="pagenum"><a name="Page_69" id="Page_69">69</a></span>

-Society’s Medal in 1857. “For thirty years,” said the President

-at the presentation, “never has the sun exhibited his disc above the

-horizon of Dessau without being confronted by Schwabe’s imperturbable

-telescope; and that appears to have happened on an average about

-300 days a-year. So, supposing that he had observed but once a-day,

-he has made 9000 observations, in the course of which he discovered

-about 4700 groups. This is, I believe, an instance of devoted persistence

-unsurpassed in the annals of astronomy. The energy of one

-man has revealed a phenomenon that had eluded the suspicion of astronomers

-for 200 years.”</p></blockquote>

-

-<h3>HAS THE MOON AN ATMOSPHERE?</h3>

-

-<p>The Moon possesses neither Sea nor Atmosphere of appreciable

-extent. Still, as a negative, in such case, is relative only

-to the capabilities of the instruments employed, the search for

-the indications of a lunar atmosphere has been renewed with

-fresh augmentation of telescopic power. Of such indications,

-the most delicate, perhaps, are those afforded by the occultation

-of a planet by the moon. The occultation of Jupiter,

-which took place on January 2, 1857, was observed with this

-reference, and is said to have exhibited no <i>hesitation</i>, or change

-of form or brightness, such as would be produced by the refraction

-or absorption of an atmosphere. As respects the sea, if

-water existed on the moon’s surface, the sun’s light reflected

-from it should be completely polarised at a certain elongation

-of the moon from the sun; and no traces of such light have

-been observed.</p>

-

-<p>MM. Baer and Maedler conclude that the moon is not entirely

-without an atmosphere, but, owing to the smallness of

-her mass, she is incapacitated from holding an extensive covering

-of gas; and they add, “it is possible that this weak envelope

-may sometimes, through local causes, in some measure

-dim or condense itself.” But if any atmosphere exists on our

-satellite, it must be, as Laplace says, more attenuated than

-what is termed a vacuum in an air-pump.</p>

-

-<p>Mr. Hopkins thinks that if there be any lunar atmosphere,

-it must be very rare in comparison with the terrestrial atmosphere,

-and inappreciable to the kind of observation by which

-it has been tested; yet the absence of any refraction of the

-light of the stars during occultation is a very refined test. Mr.

-Nasmyth observes that “the sudden disappearance of the stars

-behind the moon, without any change or diminution of her

-brilliancy, is one of the most beautiful phenomena that can be

-witnessed.”</p>

-

-<p>Sir John Herschel observes: The fact of the moon turning

-always the same face towards the earth is, in all probability,

-the result of an elongation of its figure in the direction of a

-line joining the centres of both the bodies, acting conjointly<span class="pagenum"><a name="Page_70" id="Page_70">70</a></span>

-with a non-coincidence of its centre of gravity with its centre

-of symmetry.</p>

-

-<p>If to this we add the supposition that the substance of the

-moon is not homogeneous, and that some considerable preponderance

-of weight is placed excentrically in it, it will be

-easily apprehended that the portion of its surface nearer to that

-heavier portion of its solid content, under all the circumstances

-of the moon’s rotation, will permanently occupy the situation

-most remote from the earth.</p>

-

-<blockquote>

-

-<p>In what regards its assumption of a definite level, air obeys precisely

-the same hydrostatical laws as water. The lunar atmosphere would

-rest upon the lunar ocean, and form in its basin a lake of air, whose

-upper portions at an altitude such as we are now contemplating would

-be of excessive tenuity, especially should the provision of air be less

-abundant in proportion than our own. It by no means follows, then,

-from the absence of visible indications of water or air on this side of the

-moon, that the other is equally destitute of them, and equally unfitted

-for maintaining animal or vegetable life. Some slight approach to such

-a state of things actually obtains on the earth itself. Nearly all the

-land is collected in one of its hemispheres, and much the larger portion

-of the sea in the opposite. There is evidently an excess of heavy material

-vertically beneath the middle of the Pacific; while not very remote

-from the point of the globe diametrically opposite rises the great table-land

-of India and the Himalaya chain, on the summits of which the air

-has not more than a third of the density it has on the sea-level, and

-from which animated existence is for ever excluded.&mdash;<i>Herschel’s Outlines</i>,

-5th edit.</p></blockquote>

-

-<h3>LIGHT OF THE MOON.</h3>

-

-<p>The actual illumination of the lunar surface is not much

-superior to that of weathered sandstone-rock in full sunshine.

-Sir John Herschel has frequently compared the moon setting

-behind the gray perpendicular façade of the Table Mountain

-at the Cape of Good Hope, illuminated by the sun just risen

-from the opposite quarter of the horizon, when it has been

-scarcely distinguishable in brightness from the rock in contact

-with it. The sun and moon being nearly at equal altitudes,

-and the atmosphere perfectly free from cloud or vapour, its

-effect is alike on both luminaries.</p>

-

-<h3>HEAT OF MOONLIGHT.</h3>

-

-<p>M. Zantedeschi has proved, by a long series of experiments

-in the Botanic Gardens at Venice, Florence, and Padua, that,

-contrary to the general opinion, the diffused rays of moonlight

-have an influence upon the organs of plants, as the Sensitive

-Plant and the <i>Desmodium gyrans</i>. The influence was feeble

-compared with that of the sun; but the action is left beyond

-further question.</p>

-

-<p>Melloni has proved that the rays of the Moon give out a<span class="pagenum"><a name="Page_71" id="Page_71">71</a></span>

-slight degree of Heat (see <i>Things not generally Known</i>, p. 7);

-and Professor Piazzi Smyth, from a point of the Peak of Teneriffe

-8840 feet above the sea-level, has found distinctly perceptible

-the heat radiated from the moon, which has been so

-often sought for in vain in a lower region.</p>

-

-<h3>SCENERY OF THE MOON.</h3>

-

-<p>By means of the telescope, mountain-peaks are distinguished

-in the ash-gray light of the larger spots and isolated brightly-shining

-points of the moon, even when the disc is already

-more than half illuminated. Lambert and Schroter have shown

-that the extremely variable intensity of the ash-gray light of

-the moon depends upon the greater or less degree of reflection

-of the sunlight which falls upon the earth, according as it is

-reflected from continuous continental masses, full of sandy deserts,

-grassy steppes, tropical forests, and barren rocky ground,

-or from large ocean surfaces. Lambert made the remarkable

-observation (14th of February 1774) of a change of the ash-coloured

-moonlight into an olive-green colour bordering upon

-yellow. “The moon, which then stood vertically over the

-Atlantic Ocean, received upon its right side the green terrestrial

-light which is reflected towards her when the sky is clear

-by the forest districts of South America.”</p>

-

-<p>Plutarch says distinctly, in his remarkable work <i>On the Face

-in the Moon</i>, that we may suppose the <i>spots</i> to be partly deep

-chasms and valleys, partly mountain-peaks, which cast long

-shadows, like Mount Athos, whose shadow reaches Lemnos.

-The spots cover about two-fifths of the whole disc. In a clear

-atmosphere, and under favourable circumstances in the position

-of the moon, some of the spots are visible to the naked eye;

-as the edge of the Apennines, the dark elevated plain Grimaldus,

-the enclosed <i>Mare Crisium</i>, and Tycho, crowded round with

-numerous mountain ridges and craters.</p>

-

-<p>Professor Alexander remarks, that a map of the eastern

-hemisphere, taken with the Bay of Bengal in the centre, would

-bear a striking resemblance to the face of the moon presented

-to us. The dark portions of the moon he considers to be continental

-elevations, as shown by measuring the average height

-of mountains above the dark and the light portions of the

-moon.</p>

-

-<p>The surface of the moon can be as distinctly seen by a good

-telescope magnifying 1000 times, as it would be if not more

-than 250 miles distant.</p>

-

-<h3>LIFE IN THE MOON.</h3>

-

-<p>A circle of one second in diameter, as seen from the earth,

-on the surface of the moon contains about a square mile.<span class="pagenum"><a name="Page_72" id="Page_72">72</a></span>

-Telescopes, therefore, must be greatly improved before we

-could expect to see signs of inhabitants, as manifested by edifices

-or changes on the surface of the soil. It should, however,

-be observed, that owing to the small density of the materials of

-the moon, and the comparatively feeble gravitation of bodies

-on her surface, muscular force would there go six times as far

-in overcoming the weight of materials as on the earth. Owing

-to the want of air, however, it seems impossible that any form

-of life analogous to those on earth can subsist there. No

-appearance indicating vegetation, or the slightest variation of

-surface which can in our opinion fairly be ascribed to change of

-season, can any where be discerned.&mdash;<i>Sir John Herschel’s Outlines.</i></p>

-

-<h3>THE MOON SEEN THROUGH LORD ROSSE’S TELESCOPE.</h3>

-

-<p>In 1846, the Rev. Dr. Scoresby had the gratification of observing

-the Moon through the stupendous telescope constructed

-by Lord Rosse at Parsonstown. It appeared like a globe of

-molten silver, and every object to the extent of 100 yards was

-quite visible. Edifices, therefore, of the size of York Minster,

-or even of the ruins of Whitby Abbey, might be easily perceived,

-if they had existed. But there was no appearance of

-any thing of that nature; neither was there any indication of

-the existence of water, or of an atmosphere. There were a

-great number of extinct volcanoes, several miles in breadth;

-through one of them there was a line of continuance about 150

-miles in length, which ran in a straight direction, like a railway.

-The general appearance, however, was like one vast ruin

-of nature; and many of the pieces of rock driven out of the

-volcanoes appeared to lie at various distances.</p>

-

-<h3>MOUNTAINS IN THE MOON.</h3>

-

-<p>By the aid of telescopes, we discern irregularities in the surface

-of the moon which can be no other than mountains and

-valleys,&mdash;for this plain reason, that we see the shadows cast

-by the former in the exact proportion as to length which they

-ought to have when we take into account the inclinations of

-the sun’s rays to that part of the moon’s surface on which they

-stand. From micrometrical measurements of the lengths of the

-shadows of the more conspicuous mountains, Messrs. Baer and

-Maedler have given a list of heights for no less than 1095 lunar

-mountains, among which occur all degrees of elevation up to

-22,823 British feet, or about 1400 feet higher than Chimborazo

-in the Andes.</p>

-

-<p>If Chimborazo were as high in proportion to the earth’s

-diameter as a mountain in the moon known by the name of<span class="pagenum"><a name="Page_73" id="Page_73">73</a></span>

-Newton is to the moon’s diameter, its peak would be more

-than sixteen miles high.</p>

-

-<p>Arago calls to mind, that with a 6000-fold magnifying

-power, which nevertheless could not be applied to the moon

-with proportionate results, the mountains upon the moon

-would appear to us just as Mont Blanc does to the naked eye

-when seen from the Lake of Geneva.</p>

-

-<p>We sometimes observe more than half the surface of the

-moon, the eastern and northern edges being more visible at

-one time, and the western or southern at another. By means

-of this libration we are enabled to see the annular mountain

-Malapert (which occasionally conceals the moon’s south pole),

-the arctic landscape round the crater of Gioja, and the large

-gray plane near Endymion, which conceals in superficial extent

-the <i>mare vaporum</i>.</p>

-

-<p>Three-sevenths of the moon are entirely concealed from our

-observation; and must always remain so, unless some new and

-unexpected disturbing causes come into play.&mdash;<i>Humboldt.</i></p>

-

-<blockquote>

-

-<p>The first object to which Galileo directed his telescope was the

-mountainous parts of the moon, when he showed how their summits

-might be measured: he found in the moon some circular districts surrounded

-on all sides by mountains similar to the form of Bohemia.

-The measurements of the mountains were made by the method of the

-tangents of the solar ray. Galileo, as Helvetius did still later, measured

-the distance of the summit of the mountains from the boundary of the

-illuminated portion at the moment when the mountain summit was

-first struck by the solar ray. Humboldt found no observations of the

-lengths of the shadows of the mountains: the summits were “much

-higher than the mountains on our earth.” The comparison is remarkable,

-since, according to Riccioli, very exaggerated ideas of the height

-of our mountains were then entertained. Galileo like all other observers

-up to the close of the eighteenth century, believed in the existence of

-many seas and of a lunar atmosphere.</p></blockquote>

-

-<h3>THE MOON AND THE WEATHER.</h3>

-

-<p>The only influence of the Moon on the Weather of which

-we have any decisive evidence is the tendency to disappearance

-of clouds under the full moon, which Sir John Herschel refers

-to its heat being much more readily absorbed in traversing

-transparent media than direct solar heat, and being extinguished

-in the upper regions of our atmosphere, never reaches the surface

-of the atmosphere at all.</p>

-

-<h3>THE MOON’S ATTRACTION.</h3>

-

-<p>Mr. G. P. Bond of Cambridge, by some investigations to

-ascertain whether the Attraction of the Moon has any effect

-upon the motion of a pendulum, and consequently upon the

-rate of a clock, has found the last to be changed to the amount<span class="pagenum"><a name="Page_74" id="Page_74">74</a></span>

-of 9/1000 of a second daily. At the equator the moon’s attraction

-changes the weight of a body only 1/7000000 of the whole;

-yet this force is sufficient to produce the vast phenomena of

-the tides!</p>

-

-<p>It is no slight evidence of the importance of analysis, that

-Laplace’s perfect theory of tides has enabled us in our astronomical

-ephemerides to predict the height of spring-tides at

-the periods of new and full moon, and thus put the inhabitants

-of the sea on their guard against the increased danger attending

-the lunar revolutions.</p>

-

-<h3>MEASURING THE EARTH BY THE MOON.</h3>

-

-<p>As the form of the Earth exerts a powerful influence on the

-motion of other cosmical bodies, and especially on that of its

-neighbouring satellite, a more perfect knowledge of the motion

-of the latter will enable us reciprocally to draw an inference

-regarding the figure of the earth. Thus, as Laplace ably remarks:

-“an astronomer, without leaving his observatory, may,

-by a comparison of lunar theory with true observations, not

-only be enabled to determine the form and size of the earth,

-but also its distance from the sun and moon; results that otherwise

-could only be arrived at by long and arduous expeditions

-to the most remote parts of both hemispheres.” The compression

-which may be inferred from lunar inequalities affords an

-advantage not yielded by individual measurements of degrees

-or experiments with the pendulum, since it gives a mean

-amount which is referable to the whole planet.&mdash;<i>Humboldt’s

-Cosmos</i>, vol. i.</p>

-

-<p>The distance of the moon from the earth is about 240,000

-miles; and if a railway-carriage were to travel at the rate of

-1000 miles a-day, it would be eight months in reaching the

-moon. But that is nothing compared with the length of time

-it would occupy a locomotive to reach the sun from the earth:

-if travelling at the rate of 1000 miles a-day, it would require

-260 years to reach it.</p>

-

-<h3>CAUSE OF ECLIPSES.</h3>

-

-<p>As the Moon is at a very moderate distance from us (astronomically

-speaking), and is in fact our nearest neighbour, while

-the sun and stars are in comparison immensely beyond it, it

-must of necessity happen that at one time or other it must

-<i>pass over</i>, and <i>occult</i> or <i>eclipse</i>, every star or planet within its

-zone, and, as seen from the <i>surface</i> of the earth, even somewhat

-beyond it. Nor is the sun itself exempt from being thus

-hidden whenever any part of the moon’s disc, in this her tortuous

-course, comes to <i>overlap</i> any part of the space occupied<span class="pagenum"><a name="Page_75" id="Page_75">75</a></span>

-in the heavens by that luminary. On these occasions is exhibited

-the most striking and impressive of all the occasional

-phenomena of astronomy, an <i>Eclipse of the Sun</i>, in which a

-greater or less portion, or even in some conjunctures the whole

-of its disc, is obscured, and, as it were, obliterated, by the superposition

-of that of the moon, which appears upon it as a

-circularly-terminated black spot, producing a temporary diminution

-of daylight, or even nocturnal darkness, so that the

-stars appear as if at midnight.&mdash;<i>Sir John Herschel’s Outlines.</i></p>

-

-<h3>VAST NUMBERS IN THE UNIVERSE.</h3>

-

-<p>The number of telescopic stars in the Milky Way uninterrupted

-by any nebulæ is estimated at 18,000,000. To compare

-this number with something analogous, Humboldt calls

-attention to the fact, that there are not in the whole heavens

-more than about 8000 stars, between the first and the sixth

-magnitudes, visible to the naked eye. The barren astonishment

-excited by numbers and dimensions in space when not

-considered with reference to applications engaging the mental

-and perceptive powers of man, is awakened in both extremes

-of the universe&mdash;in the celestial bodies as in the minutest

-animalcules. A cubic inch of the polishing slate of Bilin contains,

-according to Ehrenberg, 40,000 millions of the siliceous

-shells of Galionellæ.</p>

-

-<h3>FOR WHAT PURPOSE WERE THE STARS CREATED?</h3>

-

-<p>Surely not (says Sir John Herschel) to illuminate <i>our</i> nights,

-which an additional moon of the thousandth part of the size of

-our own would do much better; nor to sparkle as a pageant

-void of meaning and reality, and bewilder us among vain conjectures.

-Useful, it is true, they are to man as points of exact

-and permanent reference; but he must have studied astronomy

-to little purpose, who can suppose man to be the only object of

-his Creator’s care, or who does not see in the vast and wonderful

-apparatus around us provision for other races of animated

-beings. The planets derive their light from the sun; but that

-cannot be the case with the stars. These doubtless, then, are

-themselves suns; and may perhaps, each in its sphere, be the

-presiding centre round which other planets, or bodies of which

-we can form no conception from any analogy offered by our

-own system, are circulating.<a name="FNanchor_19" id="FNanchor_19" href="#Footnote_19" class="fnanchor">19</a></p>

-

-<h3>NUMBER OF STARS.</h3>

-

-<p>Various estimates have been hazarded on the Number of

-Stars throughout the whole heavens visible to us by the aid of<span class="pagenum"><a name="Page_76" id="Page_76">76</a></span>

-our colossal telescopes. Struve assumes for Herschel’s 20-feet

-reflector, that a magnifying power of 180 would give 5,800,000

-for the number of stars lying within the zones extending 30°

-on either side of the equator, and 20,374,000 for the whole

-heavens. Sir William Herschel conjectured that 18,000,000 of

-stars in the Milky Way might be seen by his still more powerful

-40-feet reflecting telescope.&mdash;<i>Humboldt’s Cosmos</i>, vol. iii.</p>

-

-<p>The assumption that the extent of the starry firmament is

-literally infinite has been made by Dr. Olbers the basis of a

-conclusion that the celestial spaces are in some slight degree

-deficient in <i>transparency</i>; so that all beyond a certain distance

-is and must remain for ever unseen, the geometrical progression

-of the extinction of light far outrunning the effect of any

-conceivable increase in the power of our telescopes. Were it

-not so, it is argued that every part of the celestial concave

-ought to shine with the brightness of the solar disc, since no

-visual ray could be so directed as not, in some point or other of

-its infinite length, to encounter such a disc.&mdash;<i>Edinburgh Review</i>,

-Jan. 1848.</p>

-

-<h3>STARS THAT HAVE DISAPPEARED.</h3>

-

-<p>Notwithstanding the great accuracy of the catalogued positions

-of telescopic fixed stars and of modern star-maps, the

-certainty of conviction that a star in the heavens has actually

-disappeared since a certain epoch can only be arrived at

-with great caution. Errors of actual observation, of reduction,

-and of the press, often disfigure the very best catalogues. The

-disappearance of a heavenly body from the place in which it

-had been before distinctly seen, may be the result of its own

-motion as much as of any such diminution of its photometric

-process as would render the waves of light too weak to excite

-our organs of sight. What we no longer see, is not necessarily

-annihilated. The idea of destruction or combustion, as applied

-to disappearing stars, belongs to the age of Tycho Brahe.

-Even Pliny makes it a question. The apparent eternal cosmical

-alternation of existence and destruction is not annihilation;

-it is merely the transition of matter into new forms, into combinations

-which are subject to new processes. Dark cosmical

-bodies may by a renewed process of light again become luminous.&mdash;<i>Humboldt’s

-Cosmos</i>, vol. iii.</p>

-

-<h3>THE POLE-STAR FOUR THOUSAND YEARS AGO.</h3>

-

-<p>Sir John Herschel, in his <i>Outlines of Astronomy</i>, thus shows

-the changes in the celestial pole in 4000 years:</p>

-

-<blockquote>

-

-<p>At the date of the erection of the Pyramid of Gizeh, which precedes

-the present epoch by nearly 4000 years, the longitudes of all the stars<span class="pagenum"><a name="Page_77" id="Page_77">77</a></span>

-were less by 55° 45′ than at present. Calculating from this datum

-the place of the pole of the heavens among the stars, it will be found

-to fall near α Draconis; its distance from that star being 3° 44′ 25″.

-This being the most conspicuous star in the immediate neighbourhood,

-was therefore the Pole Star of that epoch. The latitude of Gizeh being

-just 30° north, and consequently the altitude of the North Pole there

-also 30°, it follows that the star in question must have had at its

-lowest culmination at Gizeh an altitude of 25° 15′ 35″. Now it is a

-remarkable fact, that of the nine pyramids still existing at Gizeh, six

-(including all the largest) have the narrow passages by which alone they

-can be entered (all which open out on the northern faces of their respective

-pyramids) inclined to the horizon downwards at angles the

-mean of which is 26° 47′. At the bottom of every one of these passages,

-therefore, the Pole Star must have been visible at its lower culmination;

-a circumstance which can hardly be supposed to have been unintentional,

-and was doubtless connected (perhaps superstitiously) with the

-astronomical observations of that star, of whose proximity to the pole

-at the epoch of the erection of these wonderful structures we are thus

-furnished with a monumental record of the most imperishable nature.</p></blockquote>

-

-<h3>THE PLEIADES.</h3>

-

-<p>The Pleiades prove that, several thousand years ago even

-as now, stars of the seventh magnitude were invisible to the

-naked eye of average visual power. The group consists of

-seven stars, of which six only, of the third, fourth, and fifth

-magnitudes, could be readily distinguished. Of these Ovid

-says (<i>Fast.</i> iv. 170):</p>

-

-<div class="poem-container">

-<div class="poem"><div class="stanza">

-<span class="iq">“Quæ septem dici, sex tamen esse solent.”<br /></span>

-</div></div>

-</div>

-

-<p class="in0">Aratus states there were only six stars visible in the Pleiades.</p>

-

-<p>One of the daughters of Atlas, Merope, the only one who

-was wedded to a mortal, was said to have veiled herself for

-very shame and to have disappeared. This is probably the

-star of the seventh magnitude, which we call Celæne; for Hipparchus,

-in his commentary on Aratus, observes that on clear

-moonless nights <i>seven stars</i> may actually be seen.</p>

-

-<p>The Pleiades were doubtless known to the rudest nations

-from the earliest times; they are also called the <i>mariner’s stars</i>.

-The name is from πλεῖν (<i>plein</i>), ‘to sail.’ The navigation of

-the Mediterranean lasted from May to the beginning of November,

-from the early rising to the early setting of the Pleiades.

-In how many beautiful effusions of poetry and sentiment has

-“the Lost Pleiad” been deplored!&mdash;and, to descend to more familiar

-illustration of this group, the “Seven Stars,” the sailors’

-favourites, and a frequent river-side public-house sign, may be

-traced to the Pleiades.</p>

-

-<h3>CHANGE OF COLOUR IN THE STARS.</h3>

-

-<p>The scintillation or twinkling of the stars is accompanied

-by variations of colour, which have been remarked from a very

-early age. M. Arago states, upon the authority of M. Babinet,<span class="pagenum"><a name="Page_78" id="Page_78">78</a></span>

-that the name of Barakesch, given by the Arabians to Sirius,

-signifies <i>the star of a thousand colours</i>; and Tycho Brahe, Kepler,

-and others, attest to similar change of colour in twinkling.

-Even soon after the invention of the telescope, Simon Marius

-remarked that by removing the eye-piece of the telescope the

-images of the stars exhibited rapid fluctuations of brightness

-and colour. In 1814 Nicholson applied to the telescope

-a smart vibration, which caused the image of the star to be

-transformed into a curved line of light returning into itself,

-and diversified by several colours; each colour occupied about

-a third of the whole length of the curve, and by applying ten

-vibrations in a second, the light of Sirius in that time passed

-through thirty changes of colour. Hence the stars in general

-shine only by a portion of their light, the effect of twinkling

-being to diminish their brightness. This phenomenon M. Arago

-explains by the principle of the interference of light.</p>

-

-<p>Ptolemy is said to have noted Sirius as a <i>red</i> star, though

-it is now white. Sirius twinkles with red and blue light, and

-Ptolemy’s eyes, like those of several other persons, may have

-been more sensitive to the <i>red</i> than to the <i>blue</i> rays.&mdash;<i>Sir David

-Brewster’s More Worlds than One</i>, p. 235.</p>

-

-<p>Some of the double stars are of very different and dissimilar

-colours; and to the revolving planetary bodies which apparently

-circulate around them, a day lightened by a red light is succeeded

-by, not a night, but a day equally brilliant, though illuminated

-only by a green light.</p>

-

-<h3>DISTANCE OF THE NEAREST FIXED STAR FROM THE EARTH.</h3>

-

-<p>Sir John Herschel wrote in 1833: “What is the distance

-of the nearest fixed star? What is the scale on which our

-visible firmament is constructed? And what proportion do its

-dimensions bear to those of our own immediate system? To this,

-however, astronomy has hitherto proved unable to supply an

-answer. All we know on this subject is negative.” To these

-questions, however, an answer can now be given. Slight

-changes of position of some of the stars, called parallax, have

-been distinctly observed and measured; and among these stars

-No. 61 Cygni of Flamstead’s catalogue has a parallax of 5″, and

-that of α Centauri has a proper motion of 4″ per annum.</p>

-

-<p>The same astronomer states that each second of parallax indicates

-a distance of 20 billions of miles, or 3¼ years’ journey of

-light. Now the light sent to us by the sun, as compared with

-that sent by Sirius and α Centauri, is about 22 thousand millions

-to 1. “Hence, from the parallax assigned above to that

-star, it is easy to conclude that its intrinsic splendour, as compared

-with that of our sun at equal distances, is 2·3247, that

-of the sun being unity. The light of Sirius is four times that<span class="pagenum"><a name="Page_79" id="Page_79">79</a></span>

-of α Centauri, and its parallax only 0·15″. This, in effect, ascribes

-to it an intrinsic splendour equal to 96·63 times that of

-α Centauri, and therefore 224·7 times that of our sun.”</p>

-

-<p>This is justly regarded as one of the most brilliant triumphs

-of astronomical science, for the delicacy of the investigation is

-almost inconceivable; yet the reasoning is as unimpeachable

-as the demonstration of a theorem of Euclid.</p>

-

-<h3>LIGHT OF A STAR SIXTEENFOLD THAT OF THE SUN.</h3>

-

-<p>The bright star in the constellation of the Lyre, termed

-Vega, is the brightest in the northern hemisphere; and the combined

-researches of Struve, father and son, have found that

-the distance of this star from the earth is no less than 130 billions

-of miles! Light travelling at the rate of 192 thousand

-miles in a second consequently occupies twenty-one years in

-passing from this star to the earth. Now it has been found,

-by comparing the light of Vega with the light of the sun, that

-if the latter were removed to the distance of 130 billions of

-miles, his apparent brightness would not amount to more than

-the sixteenth part of the apparent brightness of Vega. We

-are therefore warranted in concluding that the light of Vega

-is equal to that of sixteen suns.</p>

-

-<h3>DIVERSITIES OF THE PLANETS.</h3>

-

-<p>In illustration of the great diversity of the physical peculiarities

-and probable condition of the planets, Sir John Herschel

-describes the intensity of solar radiation as nearly seven times

-greater on Mercury than on the earth, and on Uranus 330 times

-less; the proportion between the two extremes being that of

-upwards of 2000 to 1. Let any one figure to himself, (adds

-Sir John,) the condition of our globe were the sun to be septupled,

-to say nothing of the greater ratio; or were it diminished

-to a seventh, or to a 300th of its actual power!

-Again, the intensity of gravity, or its efficacy in counteracting

-muscular power and repressing animal activity, on Jupiter

-is nearly two-and-a-half times that on the earth; on

-Mars not more than one-half; on the moon one-sixth; and on

-the smaller planets probably not more than one-twentieth;

-giving a scale of which the extremes are in the proportion of

-sixty to one. Lastly, the density of Saturn hardly exceeds one-eighth

-of the mean density of the earth, so that it must consist

-of materials not much heavier than cork.</p>

-

-<blockquote>

-

-<p>Jupiter is eleven times, Saturn ten times, Uranus five times, and

-Neptune nearly six times, the diameter of our earth.</p>

-

-<p>These four bodies revolve in space at such distances from the sun,

-that if it were possible to start thence for each in succession, and to travel

-at the railway speed of 33 miles per hour, the traveller would reach</p>

-

-<p><span class="pagenum"><a name="Page_80" id="Page_80">80</a></span></p>

-

-<table summary="Time to travel by train to some planets">

-  <tr>

-    <td class="tdl">Jupiter in</td>

-    <td class="tdr">1712</td>

-    <td class="tdc lrpad">years</td></tr>

-  <tr>

-    <td class="tdl">Saturn</td>

-    <td class="tdr">3113</td>

-    <td class="tdc">”</td></tr>

-  <tr>

-    <td class="tdl">Uranus</td>

-    <td class="tdr">6226</td>

-    <td class="tdc">”</td></tr>

-  <tr>

-    <td class="tdl">Neptune</td>

-    <td class="tdr">9685</td>

-    <td class="tdc">”</td></tr>

-</table>

-

-<p class="in0">If, therefore, a person had commenced his journey at the period of the

-Christian era, he would now have to travel nearly 1300 years before he

-would arrive at the planet Saturn; more than 4300 years before he

-would reach Uranus; and no less than 7800 years before he could reach

-the orbit of Neptune.</p>

-

-<p>Yet the light which comes to us from these remote confines of the

-solar system first issued from the sun, and is then reflected from the

-surface of the planet. When the telescope is turned towards Neptune,

-the observer’s eye sees the object by means of light that issued from

-the sun eight hours before, and which since then has passed nearly

-twice through that vast space which railway speed would require almost

-a century of centuries to accomplish.&mdash;<i>Bouvier’s Familiar Astronomy.</i></p></blockquote>

-

-<h3>GRAND RESULTS OF THE DISCOVERY OF JUPITER’S

-SATELLITES.</h3>

-

-<p>This discovery, one of the first fruits of the invention of the

-telescope, and of Galileo’s early and happy idea of directing its

-newly-found powers to the examination of the heavens, forms

-one of the most memorable epochs in the history of astronomy.

-The first astronomical solution of the great problem of <i>the

-longitude</i>, practically the most important for the interests of

-mankind which has ever been brought under the dominion of

-strict scientific principles, dates immediately from this discovery.

-The final and conclusive establishment of the Copernican

-system of astronomy may also be considered as referable

-to the discovery and study of this exquisite miniature system,

-in which the laws of the planetary motions, as ascertained by

-Kepler, and specially that which connects their periods and

-distances, were specially traced, and found to be satisfactorily

-maintained. And (as if to accumulate historical interest on

-this point) it is to the observation of the eclipses of Jupiter’s

-satellites that we owe the grand discovery of the aberration of

-light, and the consequent determination of the enormous velocity

-of that wonderful element&mdash;192,000 miles per second. Mr.

-Dawes, in 1849, first noticed the existence of round, well-defined,

-bright spots on the belts of Jupiter. They vary in situation

-and number, as many as ten having been seen on one

-occasion. As the belts of Jupiter have been ascribed to the

-existence of currents analogous to our trade-winds, causing the

-body of Jupiter to be visible through his cloudy atmosphere, Sir

-John Herschel conjectures that those bright spots may possibly

-be insulated masses of clouds of local origin, similar to the

-cumuli which sometimes cap ascending columns of vapour in

-our atmosphere.</p>

-

-<p>It would require nearly 1300 globes of the size of our earth<span class="pagenum"><a name="Page_81" id="Page_81">81</a></span>

-to make one of the bulk of Jupiter. A railway-engine travelling

-at the rate of thirty-three miles an hour would travel

-round the earth in a month, but would require more than

-eleven months to perform a journey round Jupiter.</p>

-

-<h3>WAS SATURN’S RING KNOWN TO THE ANCIENTS?</h3>

-

-<p>In Maurice’s <i>Indian Antiquities</i> is an engraving of Sani,

-the Saturn of the Hindoos, taken from an image in a very ancient

-pagoda, which represents the deity encompassed by a <i>ring</i>

-formed of two serpents. Hence it is inferred that the ancients

-were acquainted with the existence of the ring of Saturn.</p>

-

-<p>Arago mentions the remarkable fact of the ring and fourth

-satellite of Saturn having been seen by Sir W. Herschel with

-his smaller telescope by the naked eye, without any eye-piece.</p>

-

-<p>The first or innermost of Saturn’s satellites is nearer to the

-central body than any other of the secondary planets. Its distance

-from the centre of Saturn is 80,088 miles; from the surface

-of the planet 47,480 miles; and from the outmost edge of

-the ring only 4916 miles. The traveller may form to himself

-an estimate of the smallness of this amount by remembering

-the statement of the well-known navigator, Captain Beechey,

-that he had in three years passed over 72,800 miles.</p>

-

-<p>According to very recent observations, Saturn’s ring is divided

-into <i>three</i> separate rings, which, from the calculations

-of Mr. Bond, an American astronomer, must be fluid. He is

-of opinion that the number of rings is continually changing,

-and that their maximum number, in the normal condition of

-the mass, does not exceed <i>twenty</i>. Mr. Bond likewise maintains

-that the power which sustains the centre of gravity of the <i>ring</i>

-is not in the planet itself, but in its satellites; and the satellites,

-though constantly disturbing the ring, actually sustain it in the

-very act of perturbation. M. Otto Struve and Mr. Bond have

-lately studied with the great Munich telescope, at the observatory

-of Pulkowa, the <i>third</i> ring of Saturn, which Mr. Lassell and

-Mr. Bond discovered to be <i>fluid</i>. They saw distinctly the dark

-interval between this fluid ring and the two old ones, and even

-measured its dimensions; and they perceived at its inner margin

-an edge feebly illuminated, which they thought might be

-the commencement of a fourth ring. These astronomers are of

-opinion, that the fluid ring is not of very recent formation, and

-that it is not subject to rapid change; and they have come to

-the extraordinary conclusion, that the inner border of the ring

-has, since the time of Huygens, been gradually approaching to

-the body of Saturn, and that <i>we may expect, sooner or later,

-perhaps in some dozen of years, to see the rings united with the

-body of the planet</i>. But this theory is by other observers pronounced

-untenable.</p>

-

-<p><span class="pagenum"><a name="Page_82" id="Page_82">82</a></span></p>

-

-<h3>TEMPERATURE OF THE PLANET MERCURY.</h3>

-

-<p>Mercury being so much nearer to the Sun than the Earth,

-he receives, it is supposed, seven times more heat than the

-earth. Mrs. Somerville says: “On Mercury, the mean heat

-arising from the intensity of the sun’s rays must be above that

-of boiling quicksilver, and water would boil even at the poles.”

-But he may be provided with an atmosphere so constituted as

-to absorb or reflect a great portion of the superabundant heat;

-so that his inhabitants (if he have any) may enjoy a climate as

-temperate as any on our globe.</p>

-

-<h3>SPECULATIONS ON VESTA AND PALLAS.</h3>

-

-<p>The most remarkable peculiarities of these ultra-zodiacal

-planets, according to Sir John Herschel, must lie in this condition

-of their state: a man placed on one of them would spring

-with ease sixty feet high, and sustain no greater shock in his

-descent than he does on the earth from leaping a yard. On

-such planets, giants might exist; and those enormous animals

-which on the earth require the buoyant power of water to counteract

-their weight, might there be denizens of the land. But

-of such speculations there is no end.</p>

-

-<h3>IS THE PLANET MARS INHABITED?</h3>

-

-<p>The opponents of the doctrine of the Plurality of Worlds

-allow that a greater probability exists of Mars being inhabited

-than in the case of any other planet. His diameter is 4100

-miles; and his surface exhibits spots of different hues,&mdash;the

-<i>seas</i>, according to Sir John Herschel, being <i>green</i>, and the land

-<i>red</i>. “The variety in the spots,” says this astronomer, “may

-arise from the planet not being destitute of atmosphere and

-cloud; and what adds greatly to the probability of this, is the

-appearance of brilliant white spots at its poles, which have

-been conjectured, with some probability, to be snow, as they

-disappear when they have been long exposed to the sun, and are

-greatest when emerging from the long night of their polar

-winter, the snow-line then extending to about six degrees from

-the pole.” “The length of the day,” says Sir David Brewster,

-“is almost exactly twenty-four hours,&mdash;the same as that

-of the earth. Continents and oceans and green savannahs

-have been observed upon Mars, and the snow of his polar regions

-has been seen to disappear with the heat of summer.”

-We actually see the clouds floating in the atmosphere of Mars,

-and there is the appearance of land and water on his disc.

-In a sketch of this planet, as seen in the pure atmosphere of

-Calcutta by Mr. Grant, it appears, to use his words, “actually<span class="pagenum"><a name="Page_83" id="Page_83">83</a></span>

-as a little world,” and as the earth would appear at a distance,

-with its seas and continents of different shades. As the diameter

-of Mars is only about one half that of our earth, the

-weight of bodies will be about one half what it would be if they

-were placed upon our globe.</p>

-

-<h3>DISCOVERY OF THE PLANET NEPTUNE.</h3>

-

-<p>This noble discovery marked in a signal manner the maturity

-of astronomical science. The proof, or at least the urgent

-presumption, of the existence of such a planet, as a means

-of accounting (by its attraction) for certain small irregularities

-observed in the motions of Uranus, was afforded almost simultaneously

-by the independent researches of two geometers,

-Mr. Adams of Cambridge, and M. Leverrier of Paris, who were

-enabled <i>from theory alone</i> to calculate whereabouts it ought

-to appear in the heavens, <i>if visible</i>, the places thus independently

-calculated agreeing surprisingly. <i>Within a single degree</i>

-of the place assigned by M. Leverrier’s calculations, and

-by him communicated to Dr. Galle of the Royal Observatory

-at Berlin, it was actually found by that astronomer on the very

-first night after the receipt of that communication, on turning

-a telescope on the spot, and comparing the stars in its immediate

-neighbourhood with those previously laid down in one of

-the zodiacal charts. This remarkable verification of an indication

-so extraordinary took place on the 23d of September 1846.<a name="FNanchor_20" id="FNanchor_20" href="#Footnote_20" class="fnanchor">20</a>&mdash;<i>Sir

-John Herschel’s Outlines.</i></p>

-

-<p>Neptune revolves round the sun in about 172 years, at a

-mean distance of thirty,&mdash;that of Uranus being nineteen, and

-that of the earth one: and by its discovery the solar system

-has been extended <i>one thousand millions of miles</i> beyond its

-former limit.</p>

-

-<p>Neptune is suspected to have a ring, but the suspicion has

-not been confirmed. It has been demonstrated by the observations

-of Mr. Lassell, M. Otto Struve, and Mr. Bond, to be

-attended by at least one satellite.</p>

-

-<p>One of the most curious facts brought to light by the discovery

-of Neptune, is the failure of Bode’s law to give an approximation

-to its distance from the sun; a striking exemplification

-of the danger of trusting to the universal applicability

-of an empirical law. After standing the severe test which led<span class="pagenum"><a name="Page_84" id="Page_84">84</a></span>

-to the discovery of the asteroids, it seemed almost contrary to

-the laws of probability that the discovery of another member

-of the planetary system should prove its failure as an universal

-rule.</p>

-

-<h3>MAGNITUDE OF COMETS.</h3>

-

-<p>Although Comets have a smaller mass than any other cosmical

-bodies&mdash;being, according to our present knowledge, probably

-not equal to 1/5000th part of the earth’s mass&mdash;yet they

-occupy the largest space, as their tails in several instances extend

-over many millions of miles. The cone of luminous vapour

-which radiates from them has been found in some cases

-(as in 1680 and 1811) equal to the length of the earth’s distance

-from the sun, forming a line that intersects both the orbits of

-Venus and Mercury. It is even probable that the vapour of

-the tails of comets mingled with our atmosphere in the years

-1819 and 1823.&mdash;<i>Humboldt’s Cosmos</i>, vol. i.</p>

-

-<h3>COMETS VISIBLE IN SUNSHINE&mdash;THE GREAT COMET OF 1843.</h3>

-

-<p>The phenomenon of the tail of a Comet being visible in

-bright Sunshine, which is recorded of the comet of 1402, occurred

-again in the case of the large comet of 1843, whose

-nucleus and tail were seen in North America on February 28th

-(according to the testimony of J.&nbsp;G. Clarke, of Portland, State

-of Maine), between one and three o’clock in the afternoon.

-The distance of the very dense nucleus from the sun’s light

-admitted of being measured with much exactness. The nucleus

-and tail (a darker space intervening) appeared like a very

-pure white cloud.&mdash;<i>American Journal of Science</i>, vol. xiv.</p>

-

-<p>E. C. Otté, the translator of Bohn’s edition of Humboldt’s

-<i>Cosmos</i>, at New Bedford, Massachusetts, U.S., Feb. 28th, 1843,

-distinctly saw the above comet between one and two in the

-afternoon. The sky at the time was intensely blue, and the

-sun shining with a dazzling brightness unknown in European

-climates.</p>

-

-<p>This very remarkable Comet, seen in England on the 17th

-of March 1843, had a nucleus with the appearance of a planetary

-disc, and the brightness of a star of the first or second magnitude.

-It had a double tail divided by a dark line. At the

-Cape of Good Hope it was seen in full daylight, and in the immediate

-vicinity of the sea; but the most remarkable fact in

-its history was its near approach to the sun, its distance from

-his surface being only <i>one-fourteenth</i> of his diameter. The heat

-to which it was exposed, therefore, was much greater than that

-which Sir Isaac Newton ascribed to the comet of 1680, namely

-200 times that of red-hot iron. Sir John Herschel has computed

-that it must have been 24 times greater than that which<span class="pagenum"><a name="Page_85" id="Page_85">85</a></span>

-was produced in the focus of Parker’s burning lens, 32 inches

-in diameter, which melts crystals of quartz and agate.<a name="FNanchor_21" id="FNanchor_21" href="#Footnote_21" class="fnanchor">21</a></p>

-

-<h3>THE MILKY WAY UNFATHOMABLE.</h3>

-

-<p>M. Struve of Pulkowa has compared Sir William Herschel’s

-opinion on this subject, as maintained in 1785, with that to

-which he was subsequently led; and arrives at the conclusion

-that, according to Sir W. Herschel himself, the visible extent

-of the Milky Way increases with the penetrating power of the

-telescopes employed; that it is impossible to discover by his

-instruments the termination of the Milky Way (as an independent

-cluster of stars); and that even his gigantic telescope

-of forty feet focal length does not enable him to extend our

-knowledge of the Milky Way, which is incapable of being

-sounded. Sir William Herschel’s <i>Theory of the Milky Way</i> was

-as follows: He considered our solar system, and all the stars

-which we can see with the eye, as placed within, and constituting

-a part of, the nebula of the Milky Way, a congeries of

-many millions of stars, so that the projection of these stars

-must form a luminous track on the concavity of the sky; and

-by estimating or counting the number of stars in different directions,

-he was able to form a rude judgment of the probable

-form of the nebula, and of the probable position of the solar

-system within it.</p>

-

-<p>This remarkable belt has maintained from the earliest ages

-the same relative situation among the stars; and, when examined

-through powerful telescopes, is found (wonderful to

-relate!) <i>to consist entirely of stars scattered by millions</i>, like

-glittering dust, on the black ground of the general heavens.</p>

-

-<h3>DISTANCES OF NEBULÆ.</h3>

-

-<p>These are truly astounding. Sir William Herschel estimated

-the distance of the annular nebula between Beta and

-Gamma Lyræ to be from our system 950 times that of Sirius;

-and a globular cluster about 5½° south-east of Beta Sir William

-computed to be one thousand three hundred billions of miles

-from our system. Again, in Scutum Sobieski is one nebula in

-the shape of a horseshoe; but which, when viewed with high

-magnifying power, presents a different appearance. Sir William

-Herschel estimated this nebula to be 900 times farther from us

-than Sirius. In some parts of its vicinity he observed 588

-stars in his telescope at one time; and he counted 258,000 in

-a space 10° long and 2½° wide. There is a globular cluster

-between the mouths of Pegasus and Equuleus, which Sir William<span class="pagenum"><a name="Page_86" id="Page_86">86</a></span>

-Herschel estimated to be 243 times farther from us than

-Sirius. Caroline Herschel discovered in the right foot of Andromeda

-a nebula of enormous dimensions, placed at an inconceivable

-distance from us: it consists probably of myriads of

-solar systems, which, taken together, are but a point in the

-universe. The nebula about 10° west of the principal star in

-Triangulum is supposed by Sir William Herschel to be 344

-times the distance of Sirius from the earth, which would be the

-immense sum of nearly seventeen thousand billions of miles

-from our planet.</p>

-

-<h3>INFINITE SPACE.</h3>

-

-<p>After the straining mind has exhausted all its resources in

-attempting to fathom the distance of the smallest telescopic

-star, or the faintest nebula, it has reached only the visible confines

-of the sidereal creation. The universe of stars is but an

-atom in the universe of space; above it, and beneath it, and

-around it, there is still infinity.</p>

-

-<h3 title="Origin of Our Planetary System.">ORIGIN OF OUR PLANETARY SYSTEM. THE NEBULAR

-HYPOTHESIS.<a name="FNanchor_22" id="FNanchor_22" href="#Footnote_22" class="fnanchor smaller">22</a></h3>

-

-<p>The commencement of our Planetary System, including the

-sun, must, according to Kant and Laplace, be regarded as an

-immense nebulous mass filling the portion of space which is

-now occupied by our system far beyond the limits of Neptune,

-our most distant planet. Even now we perhaps see similar

-masses in the distant regions of the firmament, as patches of

-nebulæ, and nebulous stars; within our system also, comets,

-the zodiacal light, the corona of the sun during a total eclipse,

-exhibit resemblances of a nebulous substance, which is so thin

-that the light of the stars passes through it unenfeebled and

-unrefracted. If we calculate the density of the mass of our

-planetary system, according to the above assumption, for the

-time when it was a nebulous sphere which reached to the path

-of the outmost planet, we should find that it would require

-several cubic miles of such matter to weigh a single grain.&mdash;<i>Professor

-Helmholtz.</i></p>

-

-<p>A quarter of a century ago, Sir John Herschel expressed his

-opinion that those nebulæ which were not resolved into individual

-stars by the highest powers then used, might be hereafter

-completely resolved by a further increase of optical power:</p>

-

-<p><span class="pagenum"><a name="Page_87" id="Page_87">87</a></span></p>

-

-<blockquote>

-

-<p>In fact, this probability has almost been converted into a certainty

-by the magnificent reflecting telescope constructed by Lord Rosse, of

-6 feet in aperture, which has resolved, or rendered resolvable, multitudes

-of nebulæ which had resisted all inferior powers. The sublimity of the

-spectacle afforded by that instrument of some of the larger globular and

-other clusters is declared by all who have witnessed it to be such as no

-words can express.<a name="FNanchor_23" id="FNanchor_23" href="#Footnote_23" class="fnanchor">23</a></p>

-

-<p>Although, therefore, nebulæ do exist, which even in this powerful

-telescope appear as nebulæ, without any sign of resolution, it may very

-reasonably be doubted whether there be really any essential physical

-distinction between nebulæ and clusters of stars, at least in the nature of

-the matter of which they consist; and whether the distinction between

-such nebulæ as are easily resolved, barely resolvable with excellent telescopes,

-and altogether irresolvable with the best, be any thing else than

-one of degree, arising merely from the excessive minuteness and multitude

-of the stars of which the latter, as compared with the former, consist.&mdash;<i>Outlines

-of Astronomy</i>, 5th edit. 1858.</p></blockquote>

-

-<p>It should be added, that Sir John Herschel considers the

-“nebular hypothesis” and the above theory of sidereal aggregation

-to stand quite independent of each other.</p>

-

-<h3>ORIGIN OF HEAT IN OUR SYSTEM.</h3>

-

-<p>Professor Helmholtz, assuming that at the commencement

-the density of the nebulous matter was a vanishing quantity,

-as compared with the present density of the sun and planets,

-calculates how much work has been performed by the condensation;

-how much of this work still exists in the form of mechanical

-force, as attraction of the planets towards the sun, and

-as <i>vis viva</i> of their motion; and finds by this how much of the

-force has been converted into heat.</p>

-

-<blockquote>

-

-<p>The result of this calculation is, that only about the 45th part of

-the original mechanical force remains as such, and that the remainder,

-converted into heat, would be sufficient to raise a mass of water equal to

-the sun and planets taken together, not less than 28,000,000 of degrees

-of the centigrade scale. For the sake of comparison, Professor Helmholtz

-mentions that the highest temperature which we can produce by

-the oxy-hydrogen blowpipe, which is sufficient to vaporise even platina,

-and which but few bodies can endure, is estimated at about 2000 degrees.

-Of the action of a temperature of 28,000,000 of such degrees we can

-form no notion. If the mass of our entire system were of pure coal,

-by the combustion of the whole of it only the 350th part of the above

-quantity would be generated.</p>

-

-<p>The store of force at present possessed by our system is equivalent

-to immense quantities of heat. If our earth were by a sudden shock

-brought to rest in her orbit&mdash;which is not to be feared in the existing

-arrangement of our system&mdash;by such a shock a quantity of heat would

-be generated equal to that produced by the combustion of fourteen such

-earths of solid coal. Making the most unfavourable assumption as to

-its capacity for heat, that is, placing it equal to that of water, the mass<span class="pagenum"><a name="Page_88" id="Page_88">88</a></span>

-of the earth would thereby be heated 11,200°; it would therefore be quite

-fused, and for the most part reduced to vapour. If, then, the earth,

-after having been thus brought to rest, should fall into the sun, which

-of course would be the case, the quantity of heat developed by the shock

-would be 400 times greater.</p></blockquote>

-

-<h3>AN ASTRONOMER’S DREAM VERIFIED.</h3>

-

-<p>The most fertile region in astronomical discovery during

-the last quarter of a century has been the planetary members

-of the solar system. In 1833, Sir John Herschel enumerated ten

-planets as visible from the earth, either by the unaided eye or

-by the telescope; the number is now increased more than fivefold.

-With the exception of Neptune, the discovery of new

-planets is confined to the class called Asteroids. These all

-revolve in elliptic orbits between those of Jupiter and Mars.

-Zitius of Wittemberg discovered an empirical law, which

-seemed to govern the distances of the planets from the sun;

-but there was a remarkable interruption in the law, according

-to which a planet ought to have been placed between Mars and

-Jupiter. Professor Bode of Berlin directed the attention of

-astronomers to the possibility of such a planet existing; and

-in seven years’ observations from the commencement of the

-present century, not one but four planets were found, differing

-widely from one another in the elements of their orbits, but

-agreeing very nearly at their mean distances from the sun with

-that of the supposed planet. This curious coincidence of the

-mean distances of these four asteroids with the planet according

-to Bode’s law, as it is generally called, led to the conjecture

-that these four planets were but fragments of the missing

-planet, blown to atoms by some internal explosion, and that

-many more fragments might exist, and be possibly discovered

-by diligent search.</p>

-

-<p>Concerning this apparently wild hypothesis, Sir John Herschel

-offered the following remarkable apology: “This may

-serve as a specimen of the dreams in which astronomers, like

-other speculators, occasionally and harmlessly indulge.”</p>

-

-<p>The dream, wild as it appeared, has been realised now. Sir

-John, in the fifth edition of his <i>Outlines of Astronomy</i>, published

-in 1858, tells us:</p>

-

-<blockquote>

-

-<p>Whatever may be thought of such a speculation as a physical hypothesis,

-this conclusion has been verified to a considerable extent as a

-matter of fact by subsequent discovery, the result of a careful and minute

-examination and mapping down of the smaller stars in and near

-the zodiac, undertaken with that express object. Zodiacal charts of this

-kind, the product of the zeal and industry of many astronomers, have

-been constructed, in which every star down to the ninth, tenth, or even

-lower magnitudes, is inserted; and these stars being compared with the

-actual stars of the heavens, the intrusion of any stranger within their

-limits cannot fail to be noticed when the comparison is systematically<span class="pagenum"><a name="Page_89" id="Page_89">89</a></span>

-conducted. The discovery of Astræa and Hebe by Professor Hencke,

-in 1845 and 1847, revived the flagging spirit of inquiry in this direction;

-with what success, the list of fifty-two asteroids, with their names and

-the dates of their discovery, will best show. The labours of our indefatigable

-countryman, Mr. Hind, have been rewarded by the discovery of

-no less than eight of them.</p></blockquote>

-

-<h3>FIRE-BALLS AND SHOOTING STARS.</h3>

-

-<p>Humboldt relates, that a friend at Popayan, at an elevation

-of 5583 feet above the sea-level, at noon, when the sun was

-shining brightly in a cloudless sky, saw his room lighted up by

-a fire-ball: he had his back towards the window at the time,

-and on turning round, perceived that great part of the path

-traversed by the fire-ball was still illuminated by the brightest

-radiance. The Germans call these phenomena <i>star-snuff</i>, from

-the vulgar notion that the lights in the firmament undergo a

-process of snuffing, or cleaning. Other nations call it <i>a shot or

-fall of stars</i>, and the English <i>star-shoot</i>. Certain tribes of the

-Orinoco term the pearly drops of dew which cover the beautiful

-leaves of the heliconia <i>star-spit</i>. In the Lithuanian mythology,

-the nature and signification of falling stars are embodied under

-nobler and more graceful symbols. The Parcæ, <i>Werpeja</i>, weave

-in heaven for the new-born child its thread of fate, attaching

-each separate thread to a star. When death approaches the

-person, the thread is rent, and the star wanes and sinks to the

-earth.&mdash;<i>Jacob Grimm.</i></p>

-

-<h3>THEORY AND EXPERIENCE.</h3>

-

-<p>In the perpetual vicissitude of theoretical views, says the

-author of <i>Giordano Bruno</i>, “most men see nothing in philosophy

-but a succession of passing meteors; whilst even the

-grander forms in which she has revealed herself share the fate

-of comets,&mdash;bodies that do not rank in popular opinion amongst

-the external and permanent works of nature, but are regarded

-as mere fugitive apparitions of igneous vapour.”</p>

-

-<h3>METEORITES FROM THE MOON.</h3>

-

-<p>The hypothesis of the selenic origin of meteoric stones depends

-upon a number of conditions, the accidental coincidence

-of which could alone convert a possible to an actual fact. The

-view of the original existence of small planetary masses in space

-is simpler, and at the same time more analogous with those

-entertained concerning the formation of other portions of the

-solar system.</p>

-

-<blockquote>

-

-<p>Diogenes Laertius thought aerolites came from the sun; but Pliny

-derides this theory. The fall of aerolites in bright sunshine, and when

-the moon’s disc was invisible, probably led to the idea of sun-stones.

-Moreover Anaxagoras regarded the sun as “a molten fiery mass;” and<span class="pagenum"><a name="Page_90" id="Page_90">90</a></span>

-Euripides, in Phaëton, terms the sun “a golden mass,” that is to say,

-a fire-coloured, brightly-shining matter, but not leading to the inference

-that aerolites are golden sun-stones. The Greek philosophers had

-four hypotheses as to their origin: telluric, from ascending exhalations;

-masses of stone raised by hurricanes; a solar origin; and lastly, an

-origin in the regions of space, as heavenly bodies which had long remained

-invisible: the last opinion entirely according with that of the

-present day.</p>

-

-<p>Chladni states that an Italian physicist, Paolo Maria Terzago, on

-the occasion of the fall of an aerolite at Milan, in 1660, by which a Franciscan

-monk was killed, was the first who surmised that aerolites were

-of selenic origin. Without any previous knowledge of this conjecture,

-Olbers was led, in 1795 (after the celebrated fall at Siena, June 16th,

-1794), to investigate the amount of the initial tangential force that

-would be required to bring to the earth masses projected from the

-moon. Olbers, Brandes, and Chaldni thought that “the velocity of 16

-to 32 miles, with which fire-balls and shooting-stars entered our atmosphere,”

-furnished a refutation to the view of their selenic origin. According

-to Olbers, it would require to reach the earth, setting aside the

-resistance of the air, an initial velocity of 8292 feet in the second; according

-to Laplace, 7862; to Biot, 8282; and to Poisson, 7595. Laplace

-states that this velocity is only five or six times as great as that of a

-cannon-ball; but Olbers has shown that “with such an initial velocity

-as 7500 or 8000 feet in a second, meteoric stones would arrive at the

-surface of our earth with a velocity of only 35,000 feet.” But the measured

-velocity of meteoric stones averages upwards of 114,000 feet to a

-second; consequently the original velocity of projection from the moon

-must be almost 110,000 feet, and therefore 14 times greater than Laplace

-asserted. It must, however, be recollected, that the opinion then so prevalent,

-of the existence of active volcanoes in the moon, where air and

-water are absent, has since been abandoned.</p>

-

-<p>Laplace elsewhere states, that in all probability aerolites “come

-from the depths of space;” yet he in another passage inclines to the hypothesis

-of their lunar origin, always, however, assuming that the stones

-projected from the moon “become satellites of our earth, describing

-around it more or less eccentric orbits, and thus not reaching its atmosphere

-until several or even many revolutions have been accomplished.”</p>

-

-<p>In Syria there is a popular belief that aerolites chiefly fall on clear

-moonlight nights. The ancients (Pliny tells us) looked for their fall

-during lunar eclipses.&mdash;<i>Abridged from Humboldt’s Cosmos</i>, vol. i. (Bohn’s

-edition).</p></blockquote>

-

-<p>Dr. Laurence Smith, U.S., accepts the “lunar theory,” and

-considers meteorites to be masses thrown off from the moon,

-the attractive power of which is but one-sixth that of the earth;

-so that bodies thrown from the surface of the moon experience

-but one sixth the retarding force they would have when thrown

-from the earth’s surface.</p>

-

-<blockquote>

-

-<p>Look again (says Dr. Smith) at the constitution of the meteorite,

-made up principally of <i>pure</i> iron. It came evidently from some place

-where there is little or no oxygen. Now the moon has no atmosphere,

-and no water on its surface. There is no oxygen there. Hurled from

-the moon, these bodies,&mdash;these masses of almost pure iron,&mdash;would

-flame in the sun like polished steel, and on reaching our atmosphere

-would burn in its oxygen until a black oxide cooled it; and this we find<span class="pagenum"><a name="Page_91" id="Page_91">91</a></span>

-to be the case with all meteorites,&mdash;the black colour is only an external

-covering.</p></blockquote>

-

-<p>Sir Humphry Davy, from facts contained in his researches

-on flame, in 1817, conceives that the light of meteors depends,

-not upon the ignition of inflammable gases, but upon that of

-solid bodies; that such is their velocity of motion, as to excite

-sufficient heat for their ignition by the compression even of

-rare air; and that the phenomena of falling stars may be explained

-by regarding them as small incombustible bodies moving

-round the earth in very eccentric orbits, and becoming

-ignited only when they pass with immense rapidity through

-the upper regions of the atmosphere; whilst those meteors

-which throw down stony bodies are, similarly circumstanced,

-combustible masses.</p>

-

-<p>Masses of iron and nickel, having all the appearance of

-aerolites or meteoric stones, have been discovered in Siberia,

-at a depth of ten metres below the surface of the earth. From

-the fact, however, that no meteoric stones are found in the

-secondary and tertiary formations, it would seem to follow that

-the phenomena of falling stones did not take place till the earth

-assumed its present conditions.</p>

-

-<h3>VAST SHOWER OF METEORS.</h3>

-

-<p>The most magnificent Shower of Meteors that has ever been

-known was that which fell during the night of November 12th,

-1833, commencing at nine o’clock in the evening, and continuing

-till the morning sun concealed the meteors from view. This

-shower extended from Canada to the northern boundary of South

-America, and over a tract of nearly 3000 miles in width.</p>

-

-<h3>IMMENSE METEORITE.</h3>

-

-<p>Mrs. Somerville mentions a Meteorite which passed within

-twenty-five miles of our planet, and was estimated to weigh

-600,000 tons, and to move with a velocity of twenty miles in a

-second. Only a small fragment of this immense mass reached

-the earth. Four instances are recorded of persons being killed

-by their fall. A block of stone fell at Ægos Potamos, <span class="smcap smaller">B.C.</span> 465,

-as large as two millstones; another at Narni, in 921, projected

-like a rock four feet above the surface of the river, in which it

-was seen to fall. The Emperor Jehangire had a sword forged

-from a mass of meteoric iron, which fell in 1620 at Jahlinder

-in the Punjab. Sixteen instances of the fall of stones in the

-British Isles are well authenticated to have occurred since 1620,

-one of them in London. It is very remarkable that no new

-chemical element has been detected in any of the numerous

-meteorites which have been analysed.</p>

-

-<p><span class="pagenum"><a name="Page_92" id="Page_92">92</a></span></p>

-

-<h3>NO FOSSIL METEORIC STONES.</h3>

-

-<p>It is (says Olbers) a remarkable but hitherto unregarded

-fact, that while shells are found in secondary and tertiary formations,

-no Fossil Meteoric Stones have as yet been discovered.

-May we conclude from this circumstance, that previous to the

-present and last modification of the earth’s surface no meteoric

-stones fell on it, though at the present time it appears probable,

-from the researches of Schreibers, that 700 fall annually?<a name="FNanchor_24" id="FNanchor_24" href="#Footnote_24" class="fnanchor">24</a></p>

-

-<h3>THE END OF OUR SYSTEM.</h3>

-

-<p>While all the phenomena in the heavens indicate a law of

-progressive creation, in which revolving matter is distributed

-into suns and planets, there are indications in our own system

-that a period has been assigned for its duration, which, sooner

-or later, it must reach. The medium which fills universal

-space, whether it be a luminiferous ether, or arise from the

-indefinite expansion of planetary atmospheres, must retard the

-bodies which move in it, even were it 360,000 millions of times

-more rare than atmospheric air; and, with its time of revolution

-gradually shortening, the satellite must return to its

-planet, the planet to its sun, and the sun to its primeval nebula.

-The fate of our system, thus deduced from mechanical laws,

-must be the fate of all others. Motion cannot be perpetuated

-in a resisting medium; and where there exist disturbing forces,

-there must be primarily derangement, and ultimately ruin.

-From the great central mass, heat may again be summoned to

-exhale nebulous matter; chemical forces may again produce

-motion, and motion may again generate systems; but, as in

-the recurring catastrophes which have desolated our earth, the

-great First Cause must preside at the dawn of each cosmical

-cycle; and, as in the animal races which were successively reproduced,

-new celestial creations of a nobler form of beauty

-and of a higher form of permanence may yet appear in the

-sidereal universe. “Behold, I create new heavens and a new

-earth, and the former shall not be remembered.” “The new

-heavens and the new earth shall remain before me.” “Let us

-look, then, according to this promise, for the new heavens and

-the new earth, wherein dwelleth righteousness.”&mdash;<i>North-British

-Review</i>, No. 3.</p>

-

-<h3>BENEFITS OF GLASS TO MAN.</h3>

-

-<p>Cuvier eloquently says: “It could not be expected that

-those Phœnician sailors who saw the sand of the shores of

-Bætica transformed by fire into a transparent Glass, should have

-at once foreseen that this new substance would prolong the<span class="pagenum"><a name="Page_93" id="Page_93">93</a></span>

-pleasures of sight to the old; that it would one day assist the

-astronomer in penetrating the depths of the heavens, and in

-numbering the stars of the Milky Way; that it would lay open

-to the naturalist a miniature world, as populous, as rich in

-wonders as that which alone seemed to have been granted to

-his senses and his contemplation: in fine, that the most simple

-and direct use of it would enable the inhabitants of the coast

-of the Baltic Sea to build palaces more magnificent than those

-of Tyre and Memphis, and to cultivate, almost under the polar

-circle, the most delicious fruit of the torrid zone.”</p>

-

-<h3>THE GALILEAN TELESCOPE.</h3>

-

-<p>Galileo appears to be justly entitled to the honour of having

-invented that form of Telescope which still bears his name;

-while we must accord to John Lippershey, the spectacle-maker

-of Middleburg, the honour of having previously invented the

-astronomical telescope. The interest excited at Venice by

-Galileo’s invention amounted almost to frenzy. On ascending

-the tower of St. Mark, that he might use one of his telescopes

-without molestation, Galileo was recognised by a crowd in the

-street, who took possession of the wondrous tube, and detained

-the impatient philosopher for several hours, till they had successively

-witnessed its effects. These instruments were soon

-manufactured in great numbers; but were purchased merely as

-philosophical toys, and were carried by travellers into every

-corner of Europe.</p>

-

-<h3>WHAT GALILEO FIRST SAW WITH HIS TELESCOPE.</h3>

-

-<p>The moon displayed to him her mountain-ranges and her

-glens, her continents and her highlands, now lying in darkness,

-now brilliant with sunshine, and undergoing all those

-variations of light and shadow which the surface of our own

-globe presents to the alpine traveller or to the aeronaut. The

-four satellites of Jupiter illuminating their planet, and suffering

-eclipses in his shadow, like our own moon; the spots on

-the sun’s disc, proving his rotation round his axis in twenty-five

-days; the crescent phases of Venus, and the triple form

-or the imperfectly developed ring of Saturn,&mdash;were the other

-discoveries in the solar system which rewarded the diligence of

-Galileo. In the starry heavens, too, thousands of new worlds

-were discovered by his telescope; and the Pleiades alone, which

-to the unassisted eye exhibit only <i>seven</i> stars, displayed to Galileo

-no fewer than <i>forty</i>.&mdash;<i>North-British Review</i>, No. 3.</p>

-

-<blockquote>

-

-<p>The first telescope “the starry Galileo” constructed with a leaden

-tube a few inches long, with a spectacle-glass, one convex and one concave,

-at each of its extremities. It magnified three times. Telescopes

-were made in London in February 1610, a year after Galileo had completed<span class="pagenum"><a name="Page_94" id="Page_94">94</a></span>

-his own (Rigaud, <i>On Harriot’s Papers</i>, 1833). They were at first

-called <i>cylinders</i>. The telescopes which Galileo constructed, and others

-of which he made use for observing Jupiter’s satellites, the phases of

-Venus, and the solar spots, possessed the gradually-increasing powers

-of magnifying four, seven, and thirty-two linear diameters; but they

-never had a higher power.&mdash;Arago, in the <i>Annuaire</i> for 1842.</p>

-

-<p>Clock-work is now applied to the equatorial telescope, so as to allow

-the observer to follow the course of any star, comet, or planet he may

-wish to observe continuously, without using his hands for the mechanical

-motion of the instrument.</p></blockquote>

-

-<h3>ANTIQUITY OF TELESCOPES.</h3>

-

-<p>Long tubes were certainly employed by Arabian astronomers,

-and very probably also by the Greeks and Romans; the

-exactness of their observations being in some degree attributable

-to their causing the object to be seen through diopters or

-slits. Abul Hassan speaks very distinctly of tubes, to the extremities

-of which ocular and object diopters were attached;

-and instruments so constructed were used in the observatory

-founded by Hulagu at Meragha. If stars be more easily discovered

-during twilight by means of tubes, and if a star be

-sooner revealed to the naked eye through a tube than without

-it, the reason lies, as Arago has truly observed, in the circumstance

-that the tube conceals a great portion of the disturbing

-light diffused in the atmospheric strata between the star and

-the eye applied to the tube. In like manner, the tube prevents

-the lateral impression of the faint light which the particles

-of air receive at night from all the other stars in the

-firmament. The intensity of the image and the size of the

-star are apparently augmented.&mdash;<i>Humboldt’s Cosmos</i>, vol. iii.

-p. 53.</p>

-

-<h3>NEWTON’S FIRST REFLECTING TELESCOPE.</h3>

-

-<p>The year 1668 may be regarded as the date of the invention

-of Newton’s Reflecting Telescope. Five years previously, James

-Gregory had described the manner of constructing a reflecting

-telescope with two concave specula; but Newton perceived the

-disadvantages to be so great, that, according to his statement,

-he “found it necessary, before attempting any thing in the

-practice, to alter the design, and place the eye-glass at the side

-of the tube rather than at the middle.” On this improved

-principle Newton constructed his telescope, which was examined

-by Charles II.; it was presented to the Royal Society

-near the end of 1671, and is carefully preserved by that distinguished

-body, with the inscription:</p>

-

-<blockquote>

-

-<p class="center">“<span class="smcap">The first Reflecting Telescope; invented by Sir Isaac Newton,<br />

-and made with his own hands.</span>”</p></blockquote>

-

-<p>Sir David Brewster describes this telescope as consisting of

-a concave metallic speculum, the radius of curvature of which<span class="pagenum"><a name="Page_95" id="Page_95">95</a></span>

-was 12-2/3 or 13 inches, so that “it collected the sun’s rays at

-the distance of 6-1/3 inches.” The rays reflected by the speculum

-were received upon a plane metallic speculum inclined 45°

-to the axis of the tube, so as to reflect them to the side of the

-tube in which there was an aperture to receive a small tube

-with a plano-convex eye-glass whose radius was one-twelfth

-of an inch, by means of which the image formed by the speculum

-was magnified 38 times. Such was the first reflecting

-telescope applied to the heavens; but Sir David Brewster describes

-this instrument as small and ill-made; and fifty years

-elapsed before telescopes of the Newtonian form became useful

-in astronomy.</p>

-

-<h3>SIR WILLIAM HERSCHEL’S GREAT TELESCOPE AT SLOUGH.</h3>

-

-<p>The plan of this Telescope was intimated by Herschel,

-through Sir Joseph Banks, to George III., who offered to defray

-the whole expense of it; a noble act of liberality, which

-has never been imitated by any other British sovereign. Towards

-the close of 1785, accordingly, Herschel began to construct his

-reflecting telescope, <i>forty feet in length</i>, and having a speculum

-<i>fully four feet in diameter</i>. The thickness of the speculum,

-which was uniform in every part, was 3½ inches, and its weight

-nearly 2118 pounds; the metal being composed of 32 copper,

-and 10·7 of tin: it was the third speculum cast, the two previous

-attempts having failed. The speculum, when not in use,

-was preserved from damp by a tin cover, fitted upon a rim of

-close-grained cloth. The tube of the telescope was 39 ft. 4 in.

-long, and its width 4 ft. 10 in.; it was made of iron, and was

-3000 lbs. lighter than if it had been made of wood. The observer

-was seated in a suspended movable seat at the mouth

-of the tube, and viewed the image of the object with a magnifying

-lens or eye-piece. The focus of the speculum, or place

-of the image, was within four inches of the lower side of the

-mouth of the tube, and came forward into the air, so that there

-was space for part of the head above the eye, to prevent it

-from intercepting many of the rays going from the object to

-the mirror. The eye-piece moved in a tube carried by a slider

-directed to the centre of the speculum, and fixed on an adjustible

-foundation at the mouth of the tube. It was completed

-on the 27th August 1789; and <i>the very first moment</i> it

-was directed to the heavens, a new body was added to the

-solar system, namely, Saturn and six of its satellites; and in

-less than a month after, the seventh satellite of Saturn, “an

-object,” says Sir John Herschel, “of a far higher order of

-difficulty.”&mdash;<i>Abridged from the North-British Review</i>, No. 3.</p>

-

-<blockquote>

-

-<p>This magnificent instrument stood on the lawn in the rear of Sir

-William Herschel’s house at Slough; and some of our readers, like ourselves,<span class="pagenum"><a name="Page_96" id="Page_96">96</a></span>

-may remember its extraordinary aspect when seen from the

-Bath coach-road, and the road to Windsor. The difficulty of managing

-so large an instrument&mdash;requiring as it did two assistants in addition

-to the observer himself and the person employed to note the time&mdash;prevented

-its being much used. Sir John Herschel, in a letter to Mr.

-Weld, states the entire cost of its construction, 4000<i>l.</i>, was defrayed by

-George III. In 1839, the woodwork of the telescope being decayed,

-Sir John Herschel had it cleared away; and piers were erected, on

-which the tube was placed, <i>that</i> being of iron, and so well preserved

-that, although not more than one-twentieth of an inch thick, when in

-the horizontal position it contained within all Sir John’s family; and

-next the two reflectors, the polishing apparatus, and portions of the

-machinery, to the amount of a great many tons. Sir John attributes

-this great strength and resistance to the internal structure of the tube,

-very similar to that patented under the name of corrugated iron-roping.

-Sir John Herschel also thinks that system of triangular arrangement

-of the woodwork was upon the principle to which “diagonal bracing”

-owes its strength.</p></blockquote>

-

-<h3>THE EARL OF ROSSE’S GREAT REFLECTING TELESCOPE.</h3>

-

-<p>Sir David Brewster has remarked, that “the long interval

-of half a century seems to be the period of hybernation during

-which the telescopic mind rests from its labours in order to acquire

-strength for some great achievement. Fifty years elapsed

-between the dwarf telescope of Newton and the large instruments

-of Hadley; other fifty years rolled on before Sir William

-Herschel constructed his magnificent telescope; and fifty years

-more passed away before the Earl of Rosse produced that colossal

-instrument which has already achieved such brilliant discoveries.”<a name="FNanchor_25" id="FNanchor_25" href="#Footnote_25" class="fnanchor">25</a></p>

-

-<p>In the improvement of the Reflecting Telescope, the first

-object has always been to increase the magnifying power and

-light by the construction of as large a mirror as possible; and

-to this point Lord Rosse’s attention was directed as early as

-1828, the field of operation being at his lordship’s seat, Birr

-Castle at Parsonstown, about fifty miles west of Dublin. For

-this high branch of scientific inquiry Lord Rosse was well fitted

-by a rare combination of “talent to devise, patience to bear

-disappointment, perseverance, profound mathematical knowledge,

-mechanical skill, and uninterrupted leisure from other

-pursuits;”<a name="FNanchor_26" id="FNanchor_26" href="#Footnote_26" class="fnanchor">26</a> all these, however, would not have been sufficient,

-had not a great command of money been added; the gigantic

-telescope we are about to describe having cost certainly not

-less than twelve thousand pounds.</p>

-

-<blockquote>

-

-<p>Lord Rosse ground and polished specula fifteen inches, two feet, and

-three feet in diameter before he commenced the colossal instrument. It

-is impossible here to detail the admirable contrivances and processes by

-which he prepared himself for this great work. He first ascertained<span class="pagenum"><a name="Page_97" id="Page_97">97</a></span>

-the most useful combination of metals for specula, both in whiteness,

-porosity, and hardness, to be copper and tin. Of this compound the reflector

-was cast in pieces, which were fixed on a bed of zinc and copper,&mdash;a

-species of brass which expanded in the same degree by heat as the

-pieces of the speculum themselves. They were ground as one body to

-a true surface, and then polished by machinery moved by a steam-engine.

-The peculiarities of this mechanism were entirely Lord Rosse’s

-invention, and the result of close calculation and observation: they were

-chiefly, placing the speculum with the face upward, regulating the temperature

-by having it immersed in water, usually at 55° Fahr., and regulating

-the pressure and velocity. This was found to work a perfect

-spherical figure in large surfaces with a degree of precision unattainable

-by the hand; the polisher, by working above and upon the face of the

-speculum, being enabled to examine the operation as it proceeded without

-removing the speculum, which, when a ton weight, is no easy matter.</p>

-

-<p>The contrivance for doing this is very beautiful. The machine is

-placed in a room at the bottom of a high tower, in the successive floors

-of which trap-doors can be opened. A mast is elevated on the top of the

-tower, so that its summit is about ninety feet <i>above</i> the speculum. A

-dial-plate is attached to the top of the mast, and a small plane speculum

-and eye-piece, with proper adjustments, are so placed that the combination

-becomes a Newtonian telescope, and the dial-plate the object.

-The last and most important part of the process of working the speculum,

-is to give it a <i>true parabolic figure</i>, that is, such a figure that each

-portion of it should reflect the incident ray to the same focus. Lord

-Rosse’s operations for this purpose consist&mdash;1st, of a stroke of the first

-eccentric, which carries the polisher along <i>one-third</i> of the diameter of

-the speculum; 2d, a transverse stroke twenty-one times slower, and

-equal to 0·27 of the same diameter, measured on the edge of the tank,

-or 1·7 beyond the centre of the polisher; 3d, a rotation of the speculum

-performed in the same time as thirty-seven of the first strokes; and

-4th, a rotation of the polisher in the same direction about sixteen times

-slower. If these rules are attended to, the machine will give the true

-parabolic figure to the speculum, whether it be <i>six inches</i> or <i>three feet

-in diameter</i>. In the three-feet speculum, the figure is so true with the

-whole aperture, that it is thrown out of focus by a motion of less than

-the <i>thirtieth of an inch</i>, “and even with a single lens of one-eighth of

-an inch focus, giving a power of 2592, the dots on a watch-dial are still

-in some degree defined.”</p></blockquote>

-

-<p>Thus was executed the three-feet speculum for the twenty-six-feet

-telescope placed upon the lawn at Parsonstown, which,

-in 1840, showed with powers up to 1000 and even 1600; and

-which resolved nebulæ into stars, and destroyed that symmetry

-of form in globular nebulæ upon which was founded the hypothesis

-of the gradual condensation of nebulous matter into suns

-and planets.<a name="FNanchor_27" id="FNanchor_27" href="#Footnote_27" class="fnanchor">27</a></p>

-

-<p>Scarcely was this instrument out of Lord Rosse’s hands,

-when he resolved to attempt by the same processes to construct<span class="pagenum"><a name="Page_98" id="Page_98">98</a></span>

-another reflector, with a speculum <i>six feet</i> in diameter and <i>fifty

-feet long</i>! and this magnificent instrument was completed early

-in 1845. The focal length of the speculum is fifty-four feet. It

-weighs four tons, and, with its supports, is seven times as heavy

-as the four-feet speculum of Sir William Herschel. The speculum

-is placed in one of the sides of a cubical wooden box, about

-eight feet wide, and to the opposite end of this box is fastened

-the tube, which is made of deal staves an inch thick, hooped

-with iron clamp-rings, like a huge cask. It carries at its upper

-end, and in the axis of the tube, a small oval speculum, six

-inches in its lesser diameter.</p>

-

-<p>The tube is about 50 feet long and 8 feet in diameter in

-the middle, and furnished with diaphragms 6½ feet in aperture.

-The late Dean of Ely walked through the tube with an umbrella

-up.</p>

-

-<p>The telescope is established between two lofty castellated

-piers 60 feet high, and is raised to different altitudes by a

-strong chain-cable attached to the top of the tube. This cable

-passes over a pulley on a frame down to a windlass on the

-ground, which is wrought by two assistants. To the frame are

-attached chain-guys fastened to the counterweights; and the

-telescope is balanced by these counterweights suspended by

-chains, which are fixed to the sides of the tube and pass over

-large iron pulleys. The immense mass of matter weighs about

-twelve tons.</p>

-

-<p>On the eastern pier is a strong semicircle of cast-iron, with

-which the telescope is connected by a racked bar, with friction-rollers

-attached to the tube by wheelwork, so that by

-means of a handle near the eye-piece, the observer can move

-the telescope along the bar on either side of the meridian, to

-the distance of an hour for an equatorial star.</p>

-

-<p>On the western pier are stairs and galleries. The observing

-gallery is moved along a railway by means of wheels and a

-winch; and the mechanism for raising the galleries to various

-altitudes is very ingenious. Sometimes the galleries, filled with

-observers, are suspended midway between the two piers, over

-a chasm sixty feet deep.</p>

-

-<p>An excellent description of this immense Telescope at

-Birr Castle will be found in Mr. Weld’s volume of <i>Vacation

-Rambles</i>.</p>

-

-<p>Sir David Brewster thus eloquently sketches the powers of

-the telescope at the close of his able description of the instrument,

-which we have in part quoted from his <i>Life of Sir Isaac

-Newton</i>.</p>

-

-<blockquote>

-

-<p>We have, in the mornings, walked again and again, and ever with

-new delight, along its mystic tube, and at midnight, with its distinguished

-architect, pondered over the marvellous sights which it dis-<span class="pagenum"><a name="Page_99" id="Page_99">99</a></span>closes,&mdash;the

-satellites and belts and rings of Saturn,&mdash;the old and new

-ring, which is advancing with its crest of waters to the body of the

-planet,&mdash;the rocks, and mountains, and valleys, and extinct volcanoes

-of the moon,&mdash;the crescent of Venus, with its mountainous outline,&mdash;the

-systems of double and triple stars,&mdash;the nebulæ and starry clusters

-of every variety of shape,&mdash;and those spiral nebular formations which

-baffle human comprehension, and constitute the greatest achievement

-in modern discovery.</p></blockquote>

-

-<p>The Astronomer Royal, Mr. Airy, alludes to the impression

-made by the enormous light of the telescope,&mdash;partly by the

-modifications produced in the appearance of nebulæ already

-figured, partly by the great number of stars seen at a distance

-from the Milky Way, and partly from the prodigious brilliancy

-of Saturn. The account given by another astronomer of the

-appearance of Jupiter was that it resembled a coach-lamp in

-the telescope; and this well expresses the blaze of light which

-is seen in the instrument.</p>

-

-<p>The Rev. Dr. Scoresby thus records the results of his visits:</p>

-

-<blockquote>

-

-<p>The range opened to us by the great telescope at Birr Castle is best,

-perhaps, apprehended by the now usual measurement&mdash;not of distances

-in miles, or millions of miles, or diameters of the earth’s orbit, but&mdash;of

-the progress of light in free space. The determination within, no

-doubt, a small proportion of error of the parallax of a considerable

-number of the fixed stars yields, according to Mr. Peters, a space betwixt

-us and the fixed stars of the smallest magnitude, the sixth, ordinarily

-visible to the naked eye, of 130 years in the flight of light. This

-information enables us, on the principles of <i>sounding the heavens</i>, suggested

-by Sir W. Herschel, with the photometrical researches on the

-stars of Dr. Wollaston and others, to carry the estimation of distances,

-and that by no means on vague assumption, to the limits of space

-opened out by the most effective telescopes. And from the guidance

-thus afforded us as to the comparative power of the six feet speculum

-in the penetration of space as already elucidated, we might fairly assume

-the fact, that if any other telescope now in use could follow the

-sun if removed to the remotest visible position, or till its light would

-require 10,000 years to reach us, the grand instrument at Parsonstown

-would follow it so far that from 20,000 to 25,000 years would be spent in

-the transmission of its light to the earth. But in the cases of clusters

-of stars, and of nebulæ exhibiting a mere speck of misty luminosity,

-from the combined light of perhaps hundreds of thousands of suns, the

-<i>penetration</i> into space, compared with the results of ordinary vision,

-must be enormous; so that it would not be difficult to show the <i>probability</i>

-that a million of years, in flight of light, would be requisite, in

-regard to the most distant, to trace the enormous interval.</p></blockquote>

-

-<h3>GIGANTIC TELESCOPES PROPOSED.</h3>

-

-<p>Hooke is said to have proposed the use of Telescopes having

-a length of upwards of 10,000 feet (or nearly two miles), in

-order to see animals in the moon! an extravagant expectation

-which Auzout considered it necessary to refute. The Capuchin

-monk Schyrle von Rheita, who was well versed in optics, had

-already spoken of the speedy practicability of constructing telescopes<span class="pagenum"><a name="Page_100" id="Page_100">100</a></span>

-that should magnify 4000 times, by means of which

-the lunar mountains might be accurately laid down.</p>

-

-<p>Optical instruments of such enormous focal lengths remind

-us of the Arabian contrivances of measurement: quadrants with

-a radius of about 190 feet, upon whose graduated limb the

-image of the sun was received as in the gnomon, through a

-small round aperture. Such a quadrant was erected at Samarcand,

-probably constructed after the model of the older

-sextants of Alchokandi, which were about sixty feet in height.</p>

-

-<h3>LATE INVENTION OF OPTICAL INSTRUMENTS.</h3>

-

-<p>A writer in the <i>North-British Review</i>, No. 50, considers it

-strange that a variety of facts which must have presented

-themselves to the most careless observer should not have led

-to the earlier construction of Optical Instruments. The ancients,

-doubtless, must have formed metallic articles with concave

-surfaces, in which the observer could not fail to see himself

-magnified; and if the radius of the concavity exceeded

-twelve inches, twice the focal distance of his eye, he had in

-his hands an extempore reflecting telescope of the Newtonian

-form, in which the concave metal was the speculum, and his

-eye the eye-glass, and which would magnify and bring near him

-the image of objects nearly behind him. Through the spherical

-drops of water suspended before his eye, an attentive observer

-might have seen magnified some minute body placed

-accidentally in its anterior focus; and in the eyes of fishes and

-quadrupeds which he used for his food, he might have seen,

-and might have extracted, the beautiful lenses which they

-contain, and which he could not fail to regard as the principal

-agents in the vision of the animals to which they belonged.

-Curiosity might have prompted him to look through these remarkable

-lenses or spheres; and had he placed the lens of the

-smallest minnow, or that of the bird, the sheep, or the ox, in

-or before a circular aperture, he would have produced a microscope

-or microscopes of excellent quality and different magnifying

-powers. No such observations seem, however, to have

-been made; and even after the invention of glass, and its conversion

-into globular vessels, through which, when filled with

-any fluid, objects are magnified, the microscope remained undiscovered.</p>

-

-<h3>A TRIAD OF CONTEMPORARY ASTRONOMERS.</h3>

-

-<p>It is a remarkable fact in the history of astronomy (says

-Sir David Brewster), that three of its most distinguished professors

-were contemporaries. Galileo was the contemporary

-of Tycho during thirty-seven years, and of Kepler during the

-fifty-nine years of his life. Galileo was born seven years before<span class="pagenum"><a name="Page_101" id="Page_101">101</a></span>

-Kepler, and survived him nearly the same time. We have not

-learned that the intellectual triumvirate of the age enjoyed

-any opportunity for mutual congratulation. What a privilege

-would it have been to have contrasted the aristocratic dignity

-of Tycho with the reckless ease of Kepler, and the manly and

-impetuous mien of the Italian sage!&mdash;<i>Brewster’s Life of Newton.</i></p>

-

-<h3>A PEASANT ASTRONOMER.</h3>

-

-<p>At about the same time that Goodricke discovered the

-variation of the remarkable periodical star Algol, or β Persei,

-one Palitzch, a farmer of Prolitz, near Dresden,&mdash;a peasant by

-station, an astronomer by nature,&mdash;from his familiar acquaintance

-with the aspect of the heavens, was led to notice, among

-so many thousand stars, Algol, as distinguished from the rest

-by its variation, and ascertained its period. The same Palitzch

-was also the first to re-discover the predicted comet of Halley

-in 1759, which he saw nearly a month before any of the astronomers,

-who, armed with their telescopes, were anxiously

-watching its return. These anecdotes carry us back to the era

-of the Chaldean shepherds.&mdash;<i>Sir John Herschel’s Outlines.</i></p>

-

-<h3>SHIRBURN-CASTLE OBSERVATORY.</h3>

-

-<p>Lord Macclesfield, the eminent mathematician, who was

-twelve years President of the Royal Society, built at his seat,

-Shirburn Castle in Oxfordshire, an Observatory, about 1739.

-It stood 100 yards south from the castle-gate, and consisted of

-a bed-chamber, a room for the transit, and the third for a mural

-quadrant. In the possession of the Royal Astronomical Society

-is a curious print representing two of Lord Macclesfield’s

-servants taking observations in the Shirburn observatory; they

-are Thomas Phelps, aged 82, who, from being a stable-boy to

-Lord-Chancellor Macclesfield, rose by his merit and genius to

-be appointed observer. His companion is John Bartlett, originally

-a shepherd, in which station he, by books and observation,

-acquired such a knowledge in computation, and of the

-heavenly bodies, as to induce Lord Macclesfield to appoint

-him assistant-observer in his observatory. Phelps was the

-person who, on December 23d, 1743, discovered the great

-comet, and made the first observation of it; an account of

-which is entered in the <i>Philosophical Transactions</i>, but not the

-name of the observer.</p>

-

-<h3>LACAILLE’S OBSERVATORY.</h3>

-

-<p>Lacaille, who made more observations than all his contemporaries

-put together, and whose researches will have the

-highest value as long as astronomy is cultivated, had an observatory

-at the Collège Mazarin, part of which is now the

-Palace of the Institute, at Paris.</p>

-

-<p><span class="pagenum"><a name="Page_102" id="Page_102">102</a></span></p>

-

-<blockquote>

-

-<p>For a long time it had been without observer or instruments; under

-Napoleon’s reign it was demolished. Lacaille never used to illuminate

-the wires of his instruments. The inner part of his observatory was

-painted black; he admitted only the faintest light, to enable him to

-see his pendulum and his paper: his left eye was devoted to the service

-of looking to the pendulum, whilst his right eye was kept shut. The

-latter was only employed to look to the telescope, and during the time

-of observation never opened but for this purpose. Thus the faintest

-light made him distinguish the wires, and he very seldom felt the necessity

-of illuminating them. Part of these blackened walls were visible

-long after the demolition of the observatory, which took place somewhat

-about 1811.&mdash;<i>Professor Mohl.</i></p></blockquote>

-

-<h3>NICETY REQUIRED IN ASTRONOMICAL CALCULATIONS.</h3>

-

-<p>In the <i>Edinburgh Review</i>, 1850, we find the following illustrations

-of the enormous propagation of minute errors:</p>

-

-<blockquote>

-

-<p>The rod used in measuring a base-line is commonly about ten feet

-long; and the astronomer may be said truly to apply that very rod to

-mete the distance of the stars. An error in placing a fine dot which

-fixes the length of the rod, amounting to one-five-thousandth of an inch

-(the thickness of a single silken fibre), will amount to an error of 70

-feet in the earth’s diameter, of 316 miles in the sun’s distance, and to

-65,200,000 miles in that of the nearest fixed star. Secondly, as the

-astronomer in his observatory has nothing further to do with ascertaining

-lengths or distances, except by calculation, his whole skill and artifice

-are exhausted in the measurement of angles; for by these alone

-spaces inaccessible can be compared. Happily, a ray of light is straight:

-were it not so (in celestial spaces at least), there would be an end of

-our astronomy. Now an angle of a second (3600 to a degree) is a subtle

-thing. It has an apparent breadth utterly invisible to the unassisted

-eye, unless accompanied with so intense a splendour (<i>e. g.</i> in the case of

-a fixed star) as actually to raise by its effect on the nerve of sight a

-spurious image having a sensible breadth. A silkworm’s fibre, such as

-we have mentioned above, subtends an angle of a second at 3½ feet

-distance; a cricket-ball, 2½ inches diameter, must be removed, in order

-to subtend a second, to 43,000 feet, or about 8 miles, where it would

-be utterly invisible to the sharpest sight aided even by a telescope of

-some power. Yet it is on the measure of one single second that the

-ascertainment of a sensible parallax in any fixed star depends; and an

-error of one-thousandth of that amount (a quantity still unmeasurable

-by the most perfect of our instruments) would place the star too far or

-too near by 200,000,000,000 miles; a space which light requires 118 days

-to travel.</p></blockquote>

-

-<h3>CAN STARS BE SEEN BY DAYLIGHT?</h3>

-

-<p>Aristotle maintains that Stars may occasionally be seen in

-the Daylight, from caverns and cisterns, as through tubes.

-Pliny alludes to the same circumstance, and mentions that

-stars have been most distinctly recognised during solar eclipses.

-Sir John Herschel has heard it stated by a celebrated optician,

-that his attention was first drawn to astronomy by the regular

-appearance, at a certain hour, for several successive days, of a

-considerable star through the shaft of a chimney. The chimney-sweepers

-who have been questioned upon this subject agree<span class="pagenum"><a name="Page_103" id="Page_103">103</a></span>

-tolerably well in stating that “they have never seen stars by

-day, but that when observed at night through deep shafts, the

-sky appeared quite near, and the stars larger.” Saussure states

-that stars have been seen with the naked eye in broad daylight,

-on the declivity of Mont Blanc, at an elevation of 12,757

-feet, as he was assured by several of the alpine guides. The

-observer must be placed entirely in the shade, and have a thick

-and massive shade above his head, else the stronger light of

-the air will disperse the faint image of the stars; these conditions

-resembling those presented by the cisterns of the ancients,

-and the chimneys above referred to. Humboldt, however,

-questions the accuracy of these evidences, adding that in the

-Cordilleras of Mexico, Quito, and Peru, at elevations of 15,000

-or 16,000 feet above the sea-level, he never could distinguish

-stars by daylight. Yet, under the ethereally pure sky of Cumana,

-in the plains near the sea-shore, Humboldt has frequently

-been able, after observing an eclipse of Jupiter’s satellites,

-to find the planet again with the naked eye, and has

-most distinctly seen it when the sun’s disc was from 18° to 20°

-above the horizon.</p>

-

-<h3>LOST HEAT OF THE SUN.</h3>

-

-<p>By the nature of our atmosphere, we are protected from

-the influence of the full flood of solar heat. The absorption

-of caloric by the air has been calculated at about one-fifth of

-the whole in passing through a column of 6000 feet, estimated

-near the earth’s surface. And we are enabled, knowing the

-increasing rarity of the upper regions of our gaseous envelope,

-in which the absorption is constantly diminishing, to prove

-that <i>about one-third of the solar heat is lost</i> by vertical transmission

-through the whole extent of our atmosphere.&mdash;<i>J.&nbsp;D.

-Forbes, F.R.S.</i>; <i>Bakerian Lecture</i>, 1842.</p>

-

-<h3>THE LONDON MONUMENT USED AS AN OBSERVATORY.</h3>

-

-<p>Soon after the completion of the Monument on Fish Street

-Hill, by Wren, in 1677, it was used by Hooke and other members

-of the Royal Society for astronomical purposes, but abandoned

-on account of the vibrations being too great for the

-nicety required in their observations. Hence arose <i>the report

-that the Monument was unsafe</i>, which has been revived in our

-time; “but,” says Elmes, “its scientific construction may bid

-defiance to the attacks of all but earthquakes for centuries to

-come.” This vibration in lofty columns is not uncommon.

-Captain Smythe, in his <i>Cycle of Celestial Objects</i>, tells us, that

-when taking observations on the summit of Pompey’s Pillar,

-near Alexandria, the mercury was sensibly affected by tremor,

-although the pillar is a solid.</p>

-

-<hr />

-

-<p><span class="pagenum"><a name="Page_104" id="Page_104">104</a></span></p>

-

-<div class="chapter"></div>

-<h2><a name="Geology" id="Geology"></a>Geology and Paleontology.</h2>

-

-<h3>IDENTITY OF ASTRONOMY AND GEOLOGY.</h3>

-

-<p>While the Astronomer is studying the form and condition and

-structure of the planets, in so far as the eye and the telescope

-can aid him, the Geologist is investigating the form and condition

-and structure of the planet to which he belongs; and it

-is from the analogy of the earth’s structure, as thus ascertained,

-that the astronomer is enabled to form any rational conjecture

-respecting the nature and constitution of the other planetary bodies.

-Astronomy and Geology, therefore, constitute the same

-science&mdash;the science of material or inorganic nature.</p>

-

-<p>When the astronomer first surveys the <i>concavity</i> of the celestial

-vault, he finds it studded with luminous bodies differing

-in magnitude and lustre, some moving to the east and others

-to the west; while by far the greater number seem fixed in

-space; and it is the business of astronomers to assign to each

-of them its proper place and sphere, to determine their true

-distance from the earth, and to arrange them in systems

-throughout the regions of sidereal space.</p>

-

-<p>In like manner, when the geologist surveys the <i>convexity</i> of

-his own globe, he finds its solid covering composed of rocks

-and beds of all shapes and kinds, lying at every possible angle,

-occupying every possible position, and all of them, generally

-speaking, at the same distance from the earth’s centre. Every

-where we see what was deep brought into visible relation with

-what was superficial&mdash;what is old with what is new&mdash;what

-preceded life with what followed it.</p>

-

-<p>Thus displayed on the surface of his globe, it becomes the

-business of the geologist to ascertain how these rocks came

-into their present places, to determine their different ages,

-and to fix the positions which they originally occupied, and

-consequently their different distances from the centre or the

-circumference of the earth. Raised from their original bed,

-the geologist must study the internal forces by which they

-were upheaved, and the agencies by which they were indurated;

-and when he finds that strata of every kind, from the primitive

-granite to the recent tertiary marine mud, have been thus

-brought within his reach, and prepared for his analysis, he

-reads their respective ages in the organic remains which they

-entomb; he studies the manner in which they have perished,<span class="pagenum"><a name="Page_105" id="Page_105">105</a></span>

-and he counts the cycles of time and of life which they disclose.&mdash;<i>Abridged

-from the North-British Review</i>, No. 9.</p>

-

-<h3>THE GEOLOGY OF ENGLAND</h3>

-

-<p class="in0">is more interesting than that of other countries, because our

-island is in a great measure an epitome of the globe; and the

-observer who is familiar with our strata, and the fossil remains

-which they include, has not only prepared himself for similar

-inquiries in other countries, but is already, as it were, by anticipation,

-acquainted with what he is to find there.&mdash;<i>Transactions

-of the Geological Society.</i></p>

-

-<h3>PROBABLE ORIGIN OF THE ENGLISH CHANNEL.</h3>

-

-<p>The proposed construction of a submarine tunnel across the

-Straits of Dover has led M. Boué, For. Mem. Geol. Soc., to

-point out the probability that the English Channel has not

-been excavated by water-action only; but owes its origin to

-one of the lines of disturbance which have fissured this portion

-of the earth’s crust: and taking this view of the case, the fissure

-probably still exists, being merely filled with comparatively

-loose material, so as to prove a serious obstacle to any

-attempt made to drive through it a submarine tunnel.&mdash;<i>Proceedings

-of the Geological Society.</i></p>

-

-<h3>HOW BOULDERS ARE TRANSPORTED TO GREAT HEIGHTS.</h3>

-

-<p>Sir Roderick Murchison has shown that in Russia, when

-the Dwina is at its maximum height, and penetrates into the

-chinks of its limestone banks, when frozen and expanded

-it causes disruptions of the rock, the entanglement of stony

-fragments in the ice. In remarkable spring floods, the stream

-so expands that in bursting it throws up its icy fragments to

-15 or 20 feet above the stream; and the waters subsiding,

-these lateral ice-heaps melt away, and leave upon the bank the

-rifled and angular blocks as evidence of the highest ice-mark.

-In Lapland, M. Böhtlingk assures us that he has found <i>large

-granitic boulders weighing several tons actually entangled and

-suspended, like birds’-nests, in the branches of pine-trees, at heights

-of 30 or 40 feet above the summer level of the stream</i>!<a name="FNanchor_28" id="FNanchor_28" href="#Footnote_28" class="fnanchor">28</a></p>

-

-<p><span class="pagenum"><a name="Page_106" id="Page_106">106</a></span></p>

-

-<h3>WHY SEA-SHELLS ARE FOUND AT GREAT HEIGHTS.</h3>

-

-<p>The action of subterranean forces in breaking through and

-elevating strata of sedimentary rocks,&mdash;of which the coast of

-Chili, in consequence of a great earthquake, furnishes an example,&mdash;leads

-to the assumption that the pelagic shells found

-by MM. Bonpland and Humboldt on the ridge of the Andes, at

-an elevation of more than 15,000 English feet, may have been

-conveyed to so extraordinary a position, not by a rising of the

-ocean, but by the agency of volcanic forces capable of elevating

-into ridges the softened crust of the earth.</p>

-

-<h3>SAND OF THE SEA AND DESERT.</h3>

-

-<p>That sand is an assemblage of small stones may be seen

-with the eye unarmed with art; yet how few are equally aware

-of the synonymous nature of the sand of the sea and of the

-land! Quartz, in the form of sand, covers almost entirely the

-bottom of the sea. It is spread over the banks of rivers, and

-forms vast plains, even at a very considerable elevation above

-the level of the sea, as the desert of Sahara in Africa, of Kobi

-in Asia, and many others. This quartz is produced, at least

-in part, from the disintegration of the primitive granite rocks.

-The currents of water carry it along, and when it is in very

-small, light, and rounded grains, even the wind transports it

-from one place to another. The hills are thus made to move

-like waves, and a deluge of sand frequently inundates the

-neighbouring countries:</p>

-

-<div class="poem-container">

-<div class="poem"><div class="stanza">

-<span class="iq">“So where o’er wide Numidian wastes extend,<br /></span>

-<span class="i0">Sudden the impetuous hurricanes descend.”&mdash;<i>Addison’s Cato.</i><br /></span>

-</div></div>

-</div>

-

-<p>To illustrate the trite axiom, that nothing is lost, let us

-glance at the most important use of sand:</p>

-

-<blockquote>

-

-<p>“Quartz in the form of sand,” observes Maltebrun, “furnishes, by

-fusion, one of the most useful substances we have, namely glass, which,

-being less hard than the crystals of quartz, can be made equally transparent,

-and is equally serviceable to our wants and to our pleasures.

-There it shines in walls of crystal in the palaces of the great, reflecting

-the charms of a hundred assembled beauties; there, in the hand of the

-philosopher, it discovers to us the worlds that revolve above us in the

-immensity of space, and the no less astonishing wonders that we tread

-beneath our feet.”</p></blockquote>

-

-<h3>PEBBLES.</h3>

-

-<p>The various heights and situations at which Pebbles are

-found have led to many erroneous conclusions as to the period

-of changes of the earth’s surface. All the banks of rivers and

-lakes, and the shores of the sea, are covered with pebbles,

-rounded by the waves which have rolled them against each<span class="pagenum"><a name="Page_107" id="Page_107">107</a></span>

-other, and which frequently seem to have brought them from

-a distance. There are also similar masses of pebbles found

-at very great elevations, to which the sea appears never to

-have been able to reach. We find them in the Alps at Valorsina,

-more than 6000 feet above the level of the sea; and on

-the mountain of Bon Homme, which is more than 1000 feet

-higher. There are some places little elevated above the level

-of the sea, which, like the famous plain of Crau, in Provence,

-are entirely paved with pebbles; while in Norway, near Quedlia,

-some mountains of considerable magnitude seem to be

-completely formed of them, and in such a manner that the

-largest pebbles occupy the summit, and their thickness and

-size diminish as you approach the base. We may include in

-the number of these confused and irregular heaps most of the

-depositions of matter brought by the river or sea, and left on

-the banks, and perhaps even those immense beds of sand which

-cover the centre of Asia and Africa. It is this circumstance

-which renders so uncertain the distinction, which it is nevertheless

-necessary to establish, between alluvial masses created

-before the commencement of history, and those which we see

-still forming under our own eyes.</p>

-

-<p>A charming monograph, entitled “Thoughts on a Pebble,”

-full of playful sentiment and graceful fancy, has been written

-by the amiable Dr. Mantell, the geologist.</p>

-

-<h3>ELEVATION OF MOUNTAIN-CHAINS.</h3>

-

-<p>Professor Ansted, in his <i>Ancient World</i>, thus characterises

-this phenomenon:</p>

-

-<blockquote>

-

-<p>These movements, described in a few words, were doubtless going

-on for many thousands and tens of thousands of revolutions of our

-planet. They were accompanied also by vast but slow changes of other

-kinds. The expansive force employed in lifting up, by mighty movements,

-the northern portion of the continent of Asia, found partial vent;

-and from partial subaqueous fissures there were poured out the tabular

-masses of basalt occurring in Central India; while an extensive area of

-depression in the Indian Ocean, marked by the coral islands of the

-Laccadives, the Maldives, the great Chagos bank, and some others, were

-in the course of depression by a counteracting movement.</p></blockquote>

-

-<p>Hitherto the processes of denudation and of elevation have

-been so far balanced as to preserve a pretty steady proportion

-of sea and dry land during geological ages; but if the internal

-temperature should be so far reduced as to be no longer capable

-of generating forces of expansion sufficient for this elevatory

-action, while the denuding forces should continue to

-act with unabated energy, the inevitable result would be, that

-every mountain-top would be in time brought low. No earthly

-barrier could declare to the ocean that there its proud waves

-should be stayed. Nothing would stop its ravages till all dry<span class="pagenum"><a name="Page_108" id="Page_108">108</a></span>

-land should be laid prostrate, to form the bed over which it

-would continue to roll an uninterrupted sea.</p>

-

-<h3>THE CHALK FORMATION.</h3>

-

-<p>Mr. Horner, F.R.S., among other things in his researches

-in the Delta, considers it extremely probable that every particle

-of Chalk in the world has at some period been circulating

-in the system of a living animal.</p>

-

-<h3>WEAR OF BUILDING-STONES.</h3>

-

-<p>Professor Henry, in an account of testing the marbles used

-in building the Capitol at Washington, states that every flash

-of lightning produces an appreciable amount of nitric acid,

-which, diffused in rain-water, acts on the carbonate of lime;

-and from specimens subjected to actual freezing, it was found

-that in ten thousand years one inch would be worn from the

-blocks by the action of frost.</p>

-

-<blockquote>

-

-<p>In 1839, a report of the examination of Sandstones, Limestones,

-and Oolites of Britain was made to the Government, with a view

-to the selection of the best material for building the new Houses of

-Parliament. For this purpose, 103 quarries were described, 96 buildings

-in England referred to, many chemical analyses of the stones were

-given, and a great number of experiments related, showing, among

-other points, the cohesive power of each stone, and the amount of disintegration

-apparent, when subjected to Brard’s process. The magnesian

-limestone, or dolomite of Bolsover Moor, was recommended, and

-finally adopted for the Houses; but the selection does not appear to

-have been so successful as might have been expected from the skill and

-labour of the investigation. It may be interesting to add, that the

-publication of the above Report (for which see <i>Year-Book of Facts</i>, 1840,

-pp. 78&ndash;80) occasioned Mr. John Mallcott to remark in the <i>Times</i> journal,

-“that all stone made use of in the immediate neighbourhood of its own

-quarries is more likely to endure that atmosphere than if it be removed

-therefrom, though only thirty or forty miles:” and the lapse of comparatively

-few years has proved the soundness of this observation.<a name="FNanchor_29" id="FNanchor_29" href="#Footnote_29" class="fnanchor">29</a></p></blockquote>

-

-<h3>PHENOMENA OF GLACIERS ILLUSTRATED.</h3>

-

-<p>Professor Tyndall, being desirous of investigating some of

-the phenomena presented by the large masses of mountain-ice,&mdash;those

-frozen rivers called Glaciers,&mdash;devised the plan of sending

-a destructive agent into the midst of a mass of ice, so as

-to break down its structure in the interior, in order to see if

-this method would reveal any thing of its internal constitution.

-Taking advantage of the bright weather of 1857, he concentrated

-a beam of sunlight by a condensing lens, so as to<span class="pagenum"><a name="Page_109" id="Page_109">109</a></span>

-form the focus of the sun’s rays in the midst of a mass of ice.

-A portion of the ice was melted, but the surrounding parts

-shone out as brilliant stars, produced by the reflection of the

-faces of the crystalline structure. On examining these brilliant

-portions with a lens, Professor Tyndall discovered that

-the structure of the ice had been broken down in symmetrical

-forms of great beauty, presenting minute stars, surrounded by

-six petals, forming a beautiful flower, the plane being always

-parallel to the plane of congelation of the ice. He then prepared

-a piece of ice, by making both its surfaces smooth and

-parallel to each other. He concentrated in the centre of the

-ice the rays of heat from the electric light; and then, placing

-the piece of ice in the electric microscope, the disc revealed

-these beautiful ice-flowers.</p>

-

-<p>A mass of ice was crushed into fragments; the small fragments

-were then placed in a cup of wood; a hollow wooden

-die, somewhat smaller than the cup, was then pressed into the

-cup of ice-fragments by the pressure of a hydraulic press, and

-the ice-fragments were immediately united into a compact cup

-of nearly transparent ice. This pressure of fragments of ice

-into a solid mass explains the formation of the glaciers and

-their origin. They are composed of particles of ice or snow;

-as they descend the sides of the mountain, the pressure of

-the snow becomes sufficiently great to compress the mass into

-solid ice, until it becomes so great as to form the beautiful

-blue ice of the glaciers. This compression, however, will not

-form the solid mass unless the temperature of the ice be

-near that of freezing water. To prove this, the lecturer cooled

-a mass of ice, by wrapping it in a piece of tinfoil and exposing

-it for some time to a bath of the ethereal solution of

-solidified carbonic-acid gas, the coldest freezing mixture known.

-This cooled mass of ice was crushed to fragments, and submitted

-to the same pressure which the other fragments had

-been exposed to without cohering in the slightest degree.&mdash;<i>Lecture

-at the Royal Institution</i>, 1858.</p>

-

-<h3>ANTIQUITY OF GLACIERS.</h3>

-

-<p>The importance of glacier agency in the past as well as

-the present condition of the earth, is undoubtedly very great.

-One of our most accomplished and ingenious geologists has,

-indeed, carried back the existence of Glaciers to an epoch of

-dim antiquity, even in the reckoning of that science whose

-chronology is counted in millions of years. Professor Ramsay

-has shown ground for believing that in the fragments of rock

-that go to make up the conglomerates of the Permian strata,

-intermediate between the Old and the New Red Sandstone,

-there is still preserved a record of the action of ice, either in<span class="pagenum"><a name="Page_110" id="Page_110">110</a></span>

-glaciers or floating icebergs, before those strata were consolidated.&mdash;<i>Saturday

-Review</i>, No. 142.</p>

-

-<h3>FLOW OF THE MER DE GLACE.</h3>

-

-<p>Michel Devouasson of Chamouni fell into a crevasse on the

-Glacier of Talefre, a feeder of the Mer de Glace, on the 29th

-of July 1836, and after a severe struggle extricated himself,

-leaving his knapsack below. The identical knapsack reappeared

-in July 1846, at a spot on the surface of the glacier

-<i>four thousand three hundred</i> feet from the place where it was

-lost, as ascertained by Professor Forbes, who himself collected

-the fragments; thus indicating the rate of flow of the icy river

-in the intervening ten years.&mdash;<i>Quarterly Review</i>, No. 202.</p>

-

-<h3>THE ALLUVIAL LAND OF EGYPT: ANCIENT POTTERY.</h3>

-

-<p>Mr. L. Horner, in his recent researches near Cairo, with the

-view of throwing light upon the geological history of the alluvial

-land of Egypt, obtained from the lowest part of the boring

-of the sediment at the colossal statue of Rameses, at a depth of

-thirty-nine feet, this curious relic of the ancient world; the

-boring instrument bringing up a fragment of pottery about an

-inch square and a quarter of an inch in thickness&mdash;the two

-surfaces being of a brick-red colour, the interior dark gray.

-According to Mr. Horner’s deductions, this fragment, having

-been found at a depth of 39 feet (if there be no fallacy in his

-reasoning), must be held to be a record of the existence of man

-13,375 years before <span class="smcap smaller">A.D.</span> 1858, reckoning by the calculated rate

-of increase of three inches and a half of alluvium in a century&mdash;11,517

-years before the Christian era, and 7625 before the

-beginning assigned by Lepsius to the reign of Menos, the

-founder of Memphis. Moreover it proves in his opinion, that

-man had already reached a state of civilisation, so far at least

-as to be able to fashion clay into vessels, and to know how

-to harden it by the action of strong heat. This calculation is

-supported by the Chevalier Bunsen, who is of opinion that the

-first epochs of the history of the human race demand at the

-least a period of 20,000 years before our era as a fair starting-point

-in the earth’s history.&mdash;<i>Proceedings of Royal Soc.</i>, 1858.</p>

-

-<blockquote>

-

-<p>Upon this theory, a Correspondent, “An Old Indigo-Planter,” writes

-to the <i>Athenæum</i>, No. 1509, the following suggestive note: “Having lived

-many years on the banks of the Ganges, I have seen the stream encroach

-on a village, undermining the bank where it stood, and deposit, as a

-natural result, bricks, pottery, &amp;c. in the bottom of the stream. On

-one occasion, I am certain that the depth of the stream where the bank

-was breaking was above 40 feet; yet in three years the current of the

-river drifted so much, that a fresh deposit of soil took place over the

-<i>débris</i> of the village, and the earth was raised to a level with the old

-bank. Now had our traveller then obtained a bit of pottery from where

-it had lain for only three years, could he reasonably draw the inference

-that it had been made 13,000 years before?”</p></blockquote>

-

-<p><span class="pagenum"><a name="Page_111" id="Page_111">111</a></span></p>

-

-<h3>SUCCESSIVE CHANGES OF THE TEMPLE OF SERAPIS.</h3>

-

-<p>The Temple of Serapis at Puzzuoli, near Naples, is perhaps,

-of all the structures raised by the hands of man, the one

-which affords most instruction to a geologist. It has not only

-undergone a wonderful succession of changes in past time, but

-is still undergoing changes of condition. This edifice was exhumed

-in 1750 from the eastern shore of the Bay of Baiæ, consisting

-partly of strata containing marine shells with fragments

-of pottery and sculpture, and partly of volcanic matter

-of sub-aerial origin. Various theories were proposed in the last

-century to explain the perforations and attached animals observed

-on the middle zone of the three erect marble columns

-until recently standing; Goethe, among the rest, suggesting

-that a lagoon had once existed in the vestibule of the temple,

-filled during a temporary incursion of the sea with salt water,

-and that marine mollusca and annelids flourished for years in

-this lagoon at twelve feet or more above the sea-level.</p>

-

-<p>This hypothesis was advanced at a time when almost any

-amount of fluctuation in the level of the sea was thought more

-probable than the slightest alteration in the level of the solid

-land. In 1807 the architect Niccolini observed that the pavement

-of the temple was dry, except when a violent south wind

-was blowing; whereas, on revisiting the temple fifteen years

-later, he found the pavement covered by salt water twice every

-day at high tide. From measurements made from 1822 to

-1838, and thence to 1845, he inferred that the sea was gaining

-annually upon the floor of the temple at the rate of about one-third

-of an inch during the first period, and about three-fourths

-of an inch during the second. Mr. Smith of Jordan Hill, from

-his visits in 1819 and 1845, found an average rise of about an

-inch annually, which was in accordance with visits made by

-Mr. Babbage in 1828, and Professor James Forbes in 1826 and

-1843. In 1852 Signor Scaecchi, at the request of Sir Charles

-Lyell, compared the depth of water on the pavement with its

-level taken by him in 1839, and found that it had gained only

-4½ inches in thirteen years, and was not so deep as when MM.

-Niccolini and Smith measured it in 1845; from which he inferred

-that after 1845 the downward movement of the land

-had ceased, and before 1852 had been converted into an upward

-movement.</p>

-

-<p>Arago and others maintained that the surface on which the

-temple stands has been depressed, has <i>remained under the sea,

-and has again been elevated</i>. Russager, however, contends that

-there is nothing in the vicinity of the temple, or in the temple

-itself, to justify this bold hypothesis. Every thing leads to the

-belief that the temple has remained unchanged in the position<span class="pagenum"><a name="Page_112" id="Page_112">112</a></span>

-in which it was originally built; but that the sea rose, surrounded

-it to a height of at least twelve feet, and again retired;

-but the elevated position of the sea continued sufficiently

-long to admit of the animals boring the pillars. This view can

-even be proved historically; for Niccolini, in a memoir published

-in 1840, gives the heights of the level of the sea in the

-Bay of Naples for a period of 1900 years, and has with much

-acuteness proved his assertions historically. The correctness

-of Russager’s opinion, he states, can be demonstrated and reduced

-to figures by means of the dates collected by Niccolini.&mdash;See

-<i>Jameson’s Journal</i>, No. 58.</p>

-

-<p>At the present time the floor is always covered with sea-water.

-On the whole, there is little doubt that the ground has sunk

-upwards of two feet during the last half-century. This gradual

-subsidence confirms in a remarkable manner Mr. Babbage’s

-conclusions&mdash;drawn from the calcareous incrustations formed

-by the hot springs on the walls of the building and from the

-ancient lines of the water-level at the base of the three columns&mdash;that

-the original subsidence was not sudden, but slow and

-by successive movements.</p>

-

-<p>Sir Charles Lyell (who, in his <i>Principles of Geology</i>, has

-given a detailed account of the several upfillings of the temple)

-considers that when the mosaic pavement was re-constructed,

-the floor of the building must have stood about twelve feet

-above the level of 1838 (or about 11½ feet above the level of the

-sea), and that it had sunk about nineteen feet below that level

-before it was elevated by the eruption of Monte Nuovo.</p>

-

-<p>We regret to add, that the columns of the temple are no

-longer in the position in which they served so many years as a

-species of self-registering hydrometer: the materials have been

-newly arranged, and thus has been torn as it were from history

-a page which can never be replaced.</p>

-

-<h3>THE GROTTO DEL CANE.</h3>

-

-<p>This “Dog Grotto” has been so much cited for its stratum

-of carbonic-acid gas covering the floor, that all geological travellers

-who visit Naples feel an interest in seeing the wonder.</p>

-

-<p>This cavern was known to Pliny. It is continually exhaling

-from its sides and floor volumes of steam mixed with carbonic-acid

-gas; but the latter, from its greater specific gravity, accumulates

-at the bottom, and flows over the step of the door.

-The upper part of the cave, therefore, is free from the gas,

-while the floor is completely covered by it. Addison, on his

-visit, made some interesting experiments. He found that a

-pistol could not be fired at the bottom; and that on laying a

-train of gunpowder and igniting it on the outside of the cavern,

-the carbonic-acid gas “could not intercept the train of<span class="pagenum"><a name="Page_113" id="Page_113">113</a></span>

-fire when it once began flashing, nor hinder it from running to

-the very end.” He found that a viper was nine minutes in

-dying on the first trial, and ten minutes on the second; this

-increased vitality being, in his opinion, attributable to the

-stock of air which it had inhaled after the first trial. Dr.

-Daubeny found that phosphorus would continue lighted at

-about two feet above the bottom; that a sulphur-match went

-out in a few minutes above it, and a wax-taper at a still higher

-level. The keeper of the cavern has a dog, upon which he

-shows the effects of the gas, which, however, are quite as well,

-if not better, seen in a torch, a lighted candle, or a pistol.</p>

-

-<p>“Unfortunately,” says Professor Silliman, “like some other

-grottoes, the enchantment of the ‘Dog Grotto’ disappears on

-a near view.” It is a little hole dug artificially in the side of a

-hill facing Lake Agnano: it is scarcely high enough for a person

-to stand upright in, and the aperture is closed by a door.

-Into this narrow cell a poor little dog is very unwillingly dragged

-and placed in a depression of the floor, where he is soon narcotised

-by the carbonic acid. The earth is warm to the hand,

-and the gas given out is very constant.</p>

-

-<h3>THE WATERS OF THE GLOBE GRADUALLY DECREASING.</h3>

-

-<p>This was maintained by M. Bory Saint Vincent, because

-the vast deserts of sand, mixed up with the salt and remains of

-marine animals, of which the surface of the globe is partly composed,

-were formerly inland seas, which have insensibly become

-dry. The Caspian, the Dead Sea, the Lake Baikal, &amp;c. will

-become dry in their turn also, when their beds will be sandy

-deserts. The inland seas, whether they have only one outlet,

-as the Mediterranean, the Red Sea, the Baltic, &amp;c., or whether

-they have several, as the Gulf of Mexico, the seas of O’Kotsk,

-of Japan, China, &amp;c., will at some future time cease to communicate

-with the great basins of the ocean; they will become

-inland seas, true Caspians, and in due time will become likewise

-dry. On all sides the waters of rivers are seen to carry

-forward in their course the soil of the continent. Alluvial

-lands, deltas, banks of sand, form themselves near the coasts,

-and in the directions of the currents; madreporic animals lay

-the foundations of new lands; and while the straits become

-closed, while the depths of the sea fill up, the level of the sea,

-which it would seem natural should become higher, is sensibly

-lower. There is, therefore, an actual diminution of liquid

-matter.</p>

-

-<h3>THE SALT LAKE OF UTAH.</h3>

-

-<p>Lieutenant Gunnison, who has surveyed the great basin of

-the Salt Lake, states the water to be about one-third salt,<span class="pagenum"><a name="Page_114" id="Page_114">114</a></span>

-which it yields on boiling. Its density is considerably greater

-than that of the Red Sea. One can hardly get the whole body

-below the surface: in a sitting position the head and shoulders

-will remain above the water, such is the strength of the brine;

-and on coming to the shore the body is covered with an incrustation

-of salt in fine crystals. During summer the lake throws

-on shore abundance of salt, while in winter it throws up Glauber

-salt plentifully. “The reason of this,” says Lieutenant

-Gunnison, “is left for the scientific to judge, and also what

-becomes of the enormous amount of fresh water poured into it

-by three or four large rivers,&mdash;Jordan, Bear, and Weber,&mdash;as

-there is no visible effect.”</p>

-

-<h3>FORCE OF RUNNING WATER.</h3>

-

-<p>It has been proved by experiment that the rapidity at the

-bottom of a stream is every where less than in any other part of

-it, and is greatest at the surface. Also, that in the middle of

-the stream the particles at the top move swifter than those at

-the sides. This slowness of the lowest and side currents is produced

-by friction; and when the rapidity is sufficiently great,

-the soil composing the sides and bottom gives way. If the water

-flows at the rate of three inches per second, it will tear up fine

-clay; six inches per second, fine sand; twelve inches per second,

-fine gravel; and three feet per second, stones the size of an

-egg.&mdash;<i>Sir Charles Lyell.</i></p>

-

-<h3>THE ARTESIAN WELL OF GRENELLE AT PARIS.</h3>

-

-<p>M. Peligot has ascertained that the Water of the Artesian

-Well of Grenelle contains not the least trace of air. Subterranean

-waters ought therefore to be <i>aerated</i> before being used as

-aliment. Accordingly, at Grenelle, has been constructed a

-tower, from the top of which the water descends in innumerable

-threads, so as to present as much surface as possible to

-the air.</p>

-

-<p>The boring of this Well by the Messrs. Mulot occupied seven

-years, one month, twenty-six days, to the depth of 1794½ English

-feet, or 194½ feet below the depth at which M. Elie de

-Beaumont foretold that water would be found. The sound, or

-borer, weighed 20,000 lb., and was treble the height of that of

-the dome of the Hôpital des Invalides at Paris. In May 1837,

-when the bore had reached 1246 feet 8 inches, the great chisel

-and 262 feet of rods fell to the bottom; and although these

-weighed five tons, M. Mulot tapped a screw on the head of the

-rods, and thus, connecting another length to them, after fifteen

-months’ labour, drew up the chisel. On another occasion, this

-chisel having been raised with great force, sank at one stroke

-85 feet 3 inches into the chalk!</p>

-

-<p><span class="pagenum"><a name="Page_115" id="Page_115">115</a></span></p>

-

-<blockquote>

-

-<p>The depth of the Grenelle Well is nearly four times the height of

-Strasburg Cathedral; more than six times the height of the Hôpital

-des Invalides at Paris; more than four times the height of St. Peter’s

-at Rome; nearly four times and a half the height of St. Paul’s, and nine

-times the height of the Monument, London. Lastly, suppose all the

-above edifices to be piled one upon each other, from the base-line of the

-Well of Grenelle, and they would but reach within 11½ feet of its surface.</p>

-

-<p>MM. Elie de Beaumont and Arago never for a moment doubted the

-final success of the work; their confidence being based on analogy, and

-on a complete acquaintance with the geological structure of the Paris

-basin, which is identical with that of the London basin beneath the

-London clay.</p>

-

-<p>In the duchy of Luxembourg is a well the depth of which surpasses

-all others of the kind. It is upwards of 1000 feet more than that of

-Grenelle near Paris.</p></blockquote>

-

-<h3>HOW THE GULF-STREAM REGULATES THE TEMPERATURE OF

-LONDON.</h3>

-

-<p>Great Britain is almost exactly under the same latitude as

-Labrador, a region of ice and snow. Apparently, the chief

-cause of the remarkable difference between the two climates

-arises from the action of the great oceanic Gulf-Stream, whereby

-this country is kept constantly encircled with waters warmed

-by a West-Indian sun.</p>

-

-<blockquote>

-

-<p>Were it not for this unceasing current from tropical seas, London,

-instead of its present moderate average winter temperature of 6° above

-the freezing-point, might for many months annually be ice-bound by a

-settled cold of 10° to 30° below that point, and have its pleasant summer

-months replaced by a season so short as not to allow corn to ripen, or

-only an alpine vegetation to flourish.</p>

-

-<p>Nor are we without evidence afforded by animal life of a greater

-cold having prevailed in this country at a late geological period. One

-case in particular occurs within eighty miles of London, at the village

-of Chillesford, near Woodbridge, where, in a bed of clayey sand of an

-age but little (geologically speaking) anterior to the London gravel, Mr.

-Prestwich has found a group of fossil shells in greater part identical

-with species now living in the seas of Greenland and of similar latitudes,

-and which must evidently, from their perfect condition and natural

-position, have existed in the place where they are now met with.&mdash;<i>Lectures

-on the Geology of Clapham, &amp;c. by Joseph Prestwich, A.R.S., F.G.S.</i></p></blockquote>

-

-<h3>SOLVENT ACTION OF COMMON SALT AT HIGH TEMPERATURES.</h3>

-

-<p>Forchhammer, after a long series of experiments, has come

-to the conclusion that Common Salt at high temperatures, such

-as prevailed at earlier periods of the earth’s history, acted as

-a general solvent, similarly to water at common temperatures.

-The amount of common salt in the earth would suffice to cover

-its whole surface with a crust ten feet in thickness.</p>

-

-<h3>FREEZING CAVERN IN RUSSIA.</h3>

-

-<p>This famous Cavern, at Ithetz Kaya-Zastchita, in the Steppes<span class="pagenum"><a name="Page_116" id="Page_116">116</a></span>

-of the Kirghis, is employed by the inhabitants as a cellar. It

-has the very remarkable property of being so intensely cold

-during the hottest summers as to be then filled with ice, which

-disappearing with cold weather, is entirely gone in winter, when

-all the country is clad in snow. The roof is hung with ever-dripping

-solid icicles, and the floor may be called a stalagmite

-of ice and frozen earth. “If,” says Sir R. Murchison, “as we

-were assured, <i>the cold is greatest when the external air is hottest

-and driest</i>, that the fall of rain and a moist atmosphere produce

-some diminution of the cold in the cave, and that upon the setting-in

-of winter the ice disappears entirely,&mdash;then indeed the

-problem is very curious.” The peasants assert that in winter

-they could sleep in the cave without their sheepskins.</p>

-

-<h3>INTERIOR TEMPERATURE OF THE EARTH: CENTRAL HEAT.</h3>

-

-<p>By the observed temperature of mines, and that at the bottom

-of artesian wells, it has been established that the rate at

-which such temperature increases as we descend varies considerably

-in different localities, where the depths are comparatively

-small; but where the depths are great, we find a much

-nearer approximation to a common rate of increase, which, as

-determined by the best observation in the deepest mines, shafts,

-and artesian wells in Western Europe, is very nearly 1° F. <i>for

-an increase in depth of fifty feet</i>.&mdash;<i>W. Hopkins, M.A., F.R.S.</i></p>

-

-<p>Humboldt states that, according to tolerably coincident

-experiments in artesian wells, it has been shown that the heat

-increases on an average about 1° for every 54·5 feet. If this

-increase can be reduced to arithmetical relations, it will follow

-that a stratum of granite would be in a state of fusion at a

-depth of nearly twenty-one geographical miles, or between

-four and five times the elevation of the highest summit of the

-Himalaya.</p>

-

-<p>The following is the opinion of Professor Silliman:</p>

-

-<blockquote>

-

-<p>That the whole interior portion of the earth, or at least a great part

-of it, is an ocean of melted rock, agitated by violent winds, though I

-dare not affirm it, is still rendered highly probable by the phenomena

-of volcanoes. The facts connected with their eruption have been ascertained

-and placed beyond a doubt. How, then, are they to be accounted

-for? The theory prevalent some years since, that they are caused by

-the combustion of immense coal-beds, is puerile and now entirely abandoned.

-All the coal in the world could not afford fuel enough for one

-of the tremendous eruptions of Vesuvius.</p></blockquote>

-

-<p>This observed increase of temperature in descending beneath

-the earth’s surface suggested the notion of a central

-incandescent nucleus still remaining in a state of fluidity from

-its elevated temperature. Hence the theory that the whole

-mass of the earth was formerly a molten fluid mass, the exterior

-portion of which, to some unknown depth, has assumed<span class="pagenum"><a name="Page_117" id="Page_117">117</a></span>

-its present solidity by the radiation of heat into surrounding

-space, and its consequent refrigeration.</p>

-

-<p>The mathematical solution of this problem of Central Heat,

-assuming such heat to exist, tells us that though the central

-portion of the earth may consist of a mass of molten matter,

-the temperature of its surface is not thereby increased by more

-than the small fraction of a degree. Poisson has calculated

-that it would require <i>a thousand millions of centuries</i> to reduce

-this fraction to a degree by half its present amount, supposing

-always the external conditions to remain unaltered. In such

-cases, the superficial temperature of the earth may, in fact, be

-considered to have approximated so near to its ultimate limit

-that it can be subject to no further sensible change.</p>

-

-<h3>DISAPPEARANCE OF VOLCANIC ISLANDS.</h3>

-

-<p>Many of the Volcanic Islands thrown up above the sea-level

-soon disappear, because the lavas and conglomerates of which

-they are formed spread over flatter surfaces, through the weight

-of the incumbent fluid; and the constant levelling process goes

-on below the sea by the action of tides and currents. Such

-islands as have effectually resisted this action are found to

-possess a solid framework of lava, supporting or defending the

-loose fragmentary materials.</p>

-

-<blockquote>

-

-<p>Among the most celebrated of these phenomena in our times may be

-mentioned the Isle of Sabrina, which rose off the coast of St. Michael’s

-in 1811, attained a circumference of one mile and a height of 300 feet,

-and disappeared in less than eight months; in the following year there

-were eighty fathoms of water in its place. In July 1831 appeared Graham’s

-Island off the coast of Sicily, which attained a mile in circumference

-and 150 or 160 feet in height; its formation much resembled

-that of Sabrina.</p></blockquote>

-

-<p>The line of ancient subterranean fire which we trace on the

-Mediterranean coasts has had a strange attestation in Graham’s

-Island, which is also described as a volcano suddenly bursting

-forth in the mid sea between Sicily and Africa; burning for

-several weeks, and throwing up an isle, or crater-cone of scoriæ

-and ashes, which had scarcely been named before it was again

-lost by subsidence beneath the sea, leaving only a shoal-bank

-to attest this strange submarine breach in the earth’s crust,

-which thus mingled fire and water in one common action.</p>

-

-<p>Floating islands are not very rare: in 1827, one was seen

-twenty leagues to the east of the Azores; it was three leagues

-in width, and covered with volcanic products, sugar-canes,

-straw, and pieces of wood.</p>

-

-<h3>PERPETUAL FIRE.</h3>

-

-<p>Not far from the Deliktash, on the side of a mountain in

-Lycia, is the Perpetual Fire described some forty years since<span class="pagenum"><a name="Page_118" id="Page_118">118</a></span>

-by Captain Beaufort. It was found by Lieutenant Spratt and

-Professor Forbes, thirty years later, as brilliant as ever, and

-somewhat increased; for besides the large flame in the corner

-of the ruins described by Beaufort, there were small jets issuing

-from crevices in the side of the crater-like cavity five or six feet

-deep. At the bottom was a shallow pool of sulphureous and

-turbid water, regarded by the Turks as a sovereign remedy for

-all skin complaints. The soot deposited from the flames was

-held to be efficacious for sore eyelids, and valued as a dye for

-the eyebrows. This phenomenon is described by Pliny as the

-flame of the Lycian Chimera.</p>

-

-<h3>ARTESIAN FIRE-SPRINGS IN CHINA.</h3>

-

-<p>According to the statement of the missionary Imbert, the

-Fire-Springs, “Ho-tsing” of the Chinese, which are sunk to

-obtain a carburetted-hydrogen gas for salt-boiling, far exceed

-our artesian springs in depth. These springs are very commonly

-more than 2000 feet deep; and a spring of continued

-flow was found to be 3197 feet deep. This natural gas has

-been used in the Chinese province Tse-tschuan for several

-thousand years; and “portable gas” (in bamboo-canes) has for

-ages been used in the city of Khiung-tscheu. More recently,

-in the village of Fredonia, in the United States, such gas has

-been used both for cooking and for illumination.</p>

-

-<h3>VOLCANIC ACTION THE GREAT AGENT OF GEOLOGICAL

-CHANGE.</h3>

-

-<blockquote>

-

-<p>Mr. James Nasmyth observes, that “the floods of molten lava which

-volcanoes eject are nothing less than remaining portions of what was

-once the condition of the entire globe when in the igneous state of its

-early physical history,&mdash;no one knows how many years ago!</p>

-

-<p>“When we behold the glow and feel the heat of molten lava, how

-vastly does it add to the interest of the sight when we consider that the

-heat we feel and the light we see are the residue of the once universal

-condition of our entire globe, on whose <i>cooled surface</i> we <i>now</i> live and

-have our being! But so it is; for if there be one great fact which geological

-research has established beyond all doubt, it is that we reside

-on the cooled surface of what was once a molten globe, and that all the

-phenomena which geology has brought to light can be most satisfactorily

-traced to the successive changes incidental to its gradual cooling

-and contraction.</p>

-

-<p>“That the influx of the sea into the yet hot and molten interior of

-the globe may occasionally occur, and enhance and vary the violence of

-the phenomenon of volcanic action, there can be little doubt; but the

-action of water in such cases is only <i>secondary</i>. But for the pre-existing

-high temperature of the interior of the earth, the influx of water would

-produce no such discharges of molten lava as generally characterise volcanic

-eruptions. Molten lava is therefore a true vestige of the Natural

-History of the Creation.”</p></blockquote>

-

-<p><span class="pagenum"><a name="Page_119" id="Page_119">119</a></span></p>

-

-<h3>THE SNOW-CAPPED VOLCANO.</h3>

-

-<p>It is but rarely that the elastic forces at work within the

-interior of our globe have succeeded in breaking through the

-spiral domes which, resplendent in the brightness of eternal

-snow, crown the summits of the Cordilleras; and even where

-these subterranean forces have opened a permanent communication

-with the atmosphere, through circular craters or long

-fissures, they rarely send forth currents of lava, but merely

-eject ignited scoriæ, steam, sulphuretted hydrogen gas, and

-jets of carbonic acid.&mdash;<i>Humboldt’s Cosmos</i>, vol. i.</p>

-

-<h3>TRAVELS OF VOLCANIC DUST.</h3>

-

-<p>On the 2d of September 1845, a quantity of Volcanic Dust

-fell in the Orkney Islands, which was supposed to have originated

-in an eruption of Hecla, in Iceland. It was subsequently

-ascertained that an eruption of that volcano took place on the

-morning of the above day (September 2), so as to leave no

-doubt of the accuracy of the conclusion. The dust had thus

-travelled about 600 miles!</p>

-

-<h3>GREAT ERUPTIONS OF VESUVIUS.</h3>

-

-<p>In the great eruption of Vesuvius, in August 1779, which

-Sir William Hamilton witnessed from his villa at Pausilippo

-in the bay of Naples, the volcano sent up white sulphureous

-smoke resembling bales of cotton, exceeding the height and

-size of the mountain itself at least four times; and in the midst

-of this vast pile of smoke, stones, scoriæ, and ashes were thrown

-up not less than 2000 feet. Next day a fountain of fire shot

-up with such height and brilliancy that the smallest objects

-could be clearly distinguished at any place within six miles or

-more of Vesuvius. But on the following day a more stupendous

-column of fire rose three times the height of Vesuvius

-(3700 feet), or more than two miles high. Among the huge

-fragments of lava thrown out during this eruption was a block

-108 feet in circumference and 17 feet high, another block

-66 feet in circumference and 19 feet high, and another 16 feet

-high and 92 feet in circumference, besides thousands of smaller

-fragments. Sir William Hamilton suggests that from a scene

-of the above kind the ancient poets took their ideas of the

-giants waging war with Jupiter.</p>

-

-<p>The eruption of June 1794, which destroyed the greater

-part of the town of Torre del Greco, was, however, the most

-violent that has been recorded after the two great eruptions of

-79 and 1631.</p>

-

-<h3>EARTH-WAVES.</h3>

-

-<p>The waves of an earthquake have been represented in their<span class="pagenum"><a name="Page_120" id="Page_120">120</a></span>

-progress, and their propagation, through rocks of different

-density and elasticity; and the causes of the rapidity of propagation,

-and its diminution by the refraction, reflection, and

-interference of the oscillations have been mathematically investigated.

-Air, water, and earth waves follow the same laws

-which are recognised by the theory of motion, at all events in

-space; but the earth-waves are accompanied in their destructive

-action by discharges of elastic vapours, and of gases, and

-mixtures of pyroxene crystals, carbon, and infusorial animalcules

-with silicious shields. The more terrific effects are, however,

-when the earth-waves are accompanied by cleavage; and,

-as in the earthquake of Riobamba, when fissures alternately

-opened and closed again, so that men saved themselves by extending

-both arms, in order to prevent their sinking.</p>

-

-<p>As a remarkable example of the closing of a fissure, Humboldt

-mentions that, during the celebrated earthquake in 1851,

-in the Neapolitan province of Basilicata, a hen was found caught

-by both feet in the street-pavement of Barile, near Melfi.</p>

-

-<p>Mr. Hopkins has very correctly shown theoretically that

-the fissures produced by earthquakes are very instructive as

-regards the formation of veins and the phenomenon of dislocation,

-the more recent vein displacing the older formation.</p>

-

-<h3>RUMBLINGS OF EARTHQUAKES.</h3>

-

-<p>When the great earthquake of Coseguina, in Nicaragua,

-took place, January 23, 1835, the subterranean noise&mdash;the

-sonorous waves in the earth&mdash;was heard at the same time on

-the island of Jamaica and on the plateau of Bogota, 8740 feet

-above the sea, at a greater distance than from Algiers to London.

-In the eruptions of the volcano on the island of St.

-Vincent, April 30, 1812, at 2 <span class="smcap smaller">A.M.</span>, a noise like the report of

-cannons was heard, without any sensible concussion of the earth,

-over a space of 160,000 geographical square miles. There have

-also been heard subterranean thunderings for two years without

-earthquakes.</p>

-

-<h3>HOW TO MEASURE AN EARTHQUAKE-SHOCK.</h3>

-

-<p>A new instrument (the Seismometer) invented for this purpose

-by M. Kreil, of Vienna, consists of a pendulum oscillating

-in every direction, but unable to turn round on its point of

-suspension; and bearing at its extremity a cylinder, which, by

-means of mechanism within it, turns on its vertical axis once

-in twenty-four hours. Next to the pendulum stands a rod bearing

-a narrow elastic arm, which slightly presses the extremity

-of a lead-pencil against the surface of the cylinder. As long as

-the pendulum is quiet, the pencil traces an uninterrupted line<span class="pagenum"><a name="Page_121" id="Page_121">121</a></span>

-on the surface of the cylinder; but as soon as it oscillates, this

-line becomes interrupted and irregular, and these irregularities

-indicate the time of the commencement of an earthquake, together

-with its duration and intensity.<a name="FNanchor_30" id="FNanchor_30" href="#Footnote_30" class="fnanchor">30</a></p>

-

-<p>Elastic fluids are doubtless the cause of the slight and perfectly

-harmless trembling of the earth’s surface, which has often

-continued for several days. The focus of this destructive agent,

-the seat of the moving force, lies far below the earth’s surface;

-but we know as little of the extent of this depth as we know of

-the chemical nature of these vapours that are so highly compressed.

-At the edges of two craters,&mdash;Vesuvius and the towering

-rock which projects beyond the great abyss of Pichincha,

-near Quito,&mdash;Humboldt has felt periodic and very regular shocks

-of earthquakes, on each occasion from twenty to thirty seconds

-before the burning scoriæ or gases were erupted. The intensity

-of the shocks was increased in proportion to the time intervening

-between them, and consequently to the length of time in

-which the vapours were accumulating. This simple fact, which

-has been attested by the evidence of so many travellers, furnishes

-us with a general solution of the phenomenon, in showing that

-active volcanoes are to be considered as safety-valves for the

-immediate neighbourhood. There are instances in which the

-earth has been shaken for many successive days in the chain of

-the Andes, in South America. In certain districts, the inhabitants

-take no more notice of the number of earthquakes than

-we in Europe take of showers of rain; yet in such a district

-Bonpland and Humboldt were compelled to dismount, from the

-restiveness of their mules, because the earth shook in a forest

-for fifteen to eighteen minutes <i>without intermission</i>.</p>

-

-<h3>EARTHQUAKES AND THE MOON.</h3>

-

-<p>From a careful discussion of several thousand earthquakes

-which have been recorded between 1801 and 1850, and a comparison

-of the periods at which they occurred with the position

-of the moon in relation to the earth, M. Perry, of Dijon, infers

-that earthquakes may possibly be the result of attraction exerted

-by that body on the supposed fluid centre of our globe,

-somewhat similar to that which she exercises on the waters of

-the ocean; and the Committee of the Institute of France have

-reported favourably upon this theory.</p>

-

-<h3>THE GREAT EARTHQUAKE OF LISBON.</h3>

-

-<p>The eloquent Humboldt remarks, that the activity of an igneous<span class="pagenum"><a name="Page_122" id="Page_122">122</a></span>

-mountain, however terrific and picturesque the spectacle

-may be which it presents to our contemplation, is always limited

-to a very small space. It is far otherwise with earthquakes,

-which, although scarcely perceptible to the eye, nevertheless

-simultaneously propagate their waves to a distance of many

-thousand miles. The great earthquake which destroyed the

-city of Lisbon, November 1st, 1755, was felt in the Alps, on

-the coast of Sweden, into the Antilles, Antigua, Barbadoes,

-and Martinique; in the great Canadian lakes, in Thuringia, in

-the flat country of northern Germany, and in the small inland

-lakes on the shores of the Baltic. Remote springs were interrupted

-in their flow,&mdash;a phenomenon attending earthquakes

-which had been noticed among the ancients by Demetrius the

-Callatian. The hot springs of Töplitz dried up and returned,

-inundating every thing around, and having their waters coloured

-with iron ochre. At Cadiz, the sea rose to an elevation

-of sixty-four feet; while in the Antilles, where the tide usually

-rises only from twenty-six to twenty-eight inches, it suddenly

-rose about twenty feet, the water being of an inky blackness.

-It has been computed that, on November 1st, 1755, a portion

-of the earth’s surface four times greater than that of Europe

-was simultaneously shaken.<a name="FNanchor_31" id="FNanchor_31" href="#Footnote_31" class="fnanchor">31</a> As yet there is no manifestation

-of force known to us (says the vivid denunciation of the philosopher),

-including even the murderous invention of our own

-race, by which a greater number of people have been killed in

-the short space of a few minutes: 60,000 were destroyed in

-Sicily in 1693, from 30,000 to 40,000 in the earthquake of Riobamba

-in 1797, and probably five times as many in Asia Minor

-and Syria under Tiberius and Justinian the elder, about the

-years 19 and 526.</p>

-

-<h3>GEOLOGICAL AGE OF THE DIAMOND.</h3>

-

-<p>The discovery of Diamonds in Russia, far from the tropical

-zone, has excited much interest among geologists. In the detritus

-on the banks of the Adolfskoi, no fewer than forty diamonds

-have been found in the gold alluvium, only twenty feet

-above the stratum in which the remains of mammoths and rhinoceroses

-are found. Hence Humboldt has concluded that the

-formation of gold-veins, and consequently of diamonds, is comparatively

-of recent date, and scarcely anterior to the destruction

-of the mammoths. Sir Roderick Murchison and M. Verneuil<span class="pagenum"><a name="Page_123" id="Page_123">123</a></span>

-have been led to the same result by different arguments.<a name="FNanchor_32" id="FNanchor_32" href="#Footnote_32" class="fnanchor">32</a></p>

-

-<h3>WHAT WAS ADAMANT?</h3>

-

-<p>Professor Tennant replies, that the Adamant described by

-Pliny was a sapphire, as proved by its form, and by the fact

-that when struck on an anvil by a hammer it would make an

-indentation in the metal. A true diamond, under such circumstances,

-would fly into a thousand pieces.</p>

-

-<h3>WHAT IS COAL?</h3>

-

-<p>The whole evidence we possess as to the nature of Coal

-proves it to have been originally a mass of vegetable matter. Its

-microscopical characters point to its having been formed on the

-spot in which we find it, to its being composed of vegetable

-tissues of various kinds, separated and changed by maceration,

-pressure, and chemical action, and to the introduction of its

-earthy matter, in a large number of instances, in a state of solution

-or fine molecular subdivision. Dr. Redfern, from whose

-communication to the British Association we quote, knows

-nothing to countenance the supposition that our coal-beds are

-mainly formed of coniferous wood, because the structures found

-in mother-coal, or the charcoal layer, have not the character of

-the glandular tissue of such wood, as has been asserted.</p>

-

-<p>Geological research has shown that the immense forests

-from which our coal is formed teemed with life. A frog as

-large as an ox existed in the swamps, and the existence of insects

-proves that the higher order of organic creation flourished

-at this epoch.</p>

-

-<p>It has been calculated that the available coal-beds in Lancashire

-amount in weight to the enormous sum of 8,400,000,000

-tons. The total annual consumption of this coal, it has been

-estimated, amounts to 3,400,120 tons; hence it is inferred that

-the coal-beds of Lancashire, at the present rate of consumption,

-will last 2470 years. Making similar calculations for the coal-fields

-of South Wales, the north of England, and Scotland, it

-will readily be perceived how ridiculous were the forebodings

-which lecturing geologists delighted to indulge in a few years

-ago.</p>

-

-<h3>TORBANE-HILL COAL.</h3>

-

-<p>The coal of Torbane Hill, Scotland, is so highly inflammable,

-that it has been disputed at law whether it be true coal, or

-only asphaltum, or bitumen. Dr. Redfern describes it as laminated,<span class="pagenum"><a name="Page_124" id="Page_124">124</a></span>

-splitting with great ease horizontally, like many cannel

-coals, and like them it may be lighted at a candle. In all parts

-of the bed stigmaria and other fossil plants occur in greater

-numbers than in most other coals; their distinct vascular tissue

-may be easily recognised by a common pocket lens, and 65½ of

-the mass consists of carbon.</p>

-

-<p>Dr. Redfern considers that all our coals may be arranged in

-a scale having the Torbane-Hill coal at the top and anthracite

-at the bottom. Anthracite is almost pure carbon; Torbane Hill

-contains less fixed carbon than most other cannels: anthracite

-is very difficult to ignite, and gives out scarcely any gas; Torbane-Hill

-burns like a candle, and yields 3000 cubic feet of gas

-per ton, more than any other known coal, its gas being also of

-greatly superior illuminating power to any other. The only

-differences which the Torbane-Hill coal presents from others

-are differences of degree, not of kind. It differs from other

-coals in being the best gas-coal, and from other cannels in being

-the best cannel.</p>

-

-<h3>HOW MALACHITE IS FORMED.</h3>

-

-<p>The rich copper-ore of the Ural, which occurs in veins or

-masses, amid metamorphic strata associated with igneous rocks,

-and even in the hollows between the eruptive rocks, is worked

-in shafts. At the bottom of one of these, 280 feet deep, has

-been found an enormous irregularly-shaped botryoidal mass of

-<i>Malachite</i> (Greek <i>malache</i>, mountain-green), sending off strings

-of green copper-ore. The upper surface of it is about 18 feet

-long and 9 wide; and it was estimated to contain 15,000 poods,

-or half a million pounds, of pure and compact malachite. Sir

-Roderick Murchison is of opinion that this wonderful subterraneous

-incrustation has been produced in the stalagmitic

-form, during a series of ages, by copper solutions emanating

-from the surrounding loose and sporous mass, and trickling

-through it to the lowest cavity upon the subjacent solid rock.

-Malachite is brought chiefly from one mine in Siberia; its value

-as raw material is nearly one-fourth that of the same weight of

-pure silver, or in a manufactured state three guineas per pound

-avoirdupois.<a name="FNanchor_33" id="FNanchor_33" href="#Footnote_33" class="fnanchor">33</a></p>

-

-<h3>LUMPS OF GOLD IN SIBERIA.</h3>

-

-<p>The gold mines south of Miask are chiefly remarkable for the

-large lumps or <i>pepites</i> of gold which are found around the Zavod

-of Zarevo-Alexandroisk. Previous to 1841 were discovered<span class="pagenum"><a name="Page_125" id="Page_125">125</a></span>

-here lumps of native gold; in that year a lump of twenty-four

-pounds was met with; and in 1843 a lump weighing about

-seventy-eight pounds English was found, and is now deposited

-with others in the Museum of the Imperial School of Mines at

-St. Petersburg.</p>

-

-<h3>SIR ISAAC NEWTON UPON BURNET’S THEORY OF THE EARTH.</h3>

-

-<p>In 1668, Dr. Thomas Burnet printed his <i>Theoria Telluris

-Sacra</i>, “an eloquent physico-theological romance,” says Sir

-David Brewster, “which was to a certain extent adopted even

-by Newton, Burnet’s friend. Abandoning, as some of the

-fathers had done, the hexaëmeron, or six days of Moses, as a

-physical reality, and having no knowledge of geological phenomena,

-he gives loose reins to his imagination, combining passages

-of Scripture with those of ancient authors, and presumptuously

-describing the future catastrophes to which the earth

-is to be exposed.” Previous to its publication, Burnet presented

-a copy of his book to Newton, and requested his opinion

-of the theory which it propounded. Newton took “exceptions

-to particular passages,” and a correspondence ensued. In one

-of Newton’s letters he treats of the formation of the earth, and

-the other planets, out of a general chaos of the figure assumed

-by the earth,&mdash;of the length of the primitive days,&mdash;of the formation

-of hills and seas, and of the creation of the two ruling

-lights as the result of the clearing up of the atmosphere. He

-considers the account of the creation in Genesis as adapted

-to the judgment of the vulgar. “Had Moses,” he says, “described

-the processes of creation as distinctly as they were in

-themselves, he would have made the narrative tedious and confused

-amongst the vulgar, and become a philosopher more than

-a prophet.” After referring to several “causes of meteors, such

-as the breaking out of vapours from below, before the earth

-was well hardened, the settling and shrinking of the whole

-globe after the upper regions or surface began to be hard,”

-Newton closes his letter with an apology for being tedious,

-which, he says, “he has the more reason to do, as he has not

-set down any thing he has well considered, or will undertake to

-defend.”&mdash;See the Letter in the Appendix to <i>Sir D. Brewster’s

-Life of Newton</i>, vol. ii.</p>

-

-<blockquote>

-

-<p>The primitive condition of the earth, and its preparation for man,

-was a subject of general speculation at the close of the seventeenth century.

-Leibnitz, like his great rival (Newton), attempted to explain the

-formation of the earth, and of the different substances which composed

-it; and he had the advantage of possessing some knowledge of geological

-phenomena: the earth he regarded as having been originally a

-burning mass, whose temperature gradually diminished till the vapours

-were condensed into a universal ocean, which covered the highest mountains,<span class="pagenum"><a name="Page_126" id="Page_126">126</a></span>

-and gradually flowed into vacuities and subterranean cavities produced

-by the consolidation of the earth’s crust. He regarded fossils as

-the real remains of plants and animals which had been buried in the

-strata; and, in speculating on the formation of mineral substances, he

-speaks of crystals as the geometry of inanimate nature.&mdash;<i>Brewster’s Life

-of Newton</i>, vol. ii. p. 100, note. (See also “The Age of the Globe,” in

-<i>Things not generally Known</i>, p. 13.)</p></blockquote>

-

-<h3>“THE FATHER OF ENGLISH GEOLOGY.”</h3>

-

-<p>In 1769 was born, the son of a yeoman of Oxfordshire, William

-Smith. When a boy he delighted to wander in the fields,

-collecting “pound-stones” (<i>Echinites</i>), “pundibs” (<i>Terebratulæ</i>),

-and other stony curiosities; and receiving little education beyond

-what he taught himself, he learned nothing of classics but

-the name. Grown to be a man, he became a land-surveyor and

-civil engineer, and was much engaged in constructing canals.

-While thus occupied, he observed that all the rocky masses

-forming the substrata of the country were gently inclined to

-the east and south-east,&mdash;that the red sandstones and marls

-above the <i>coal-measures</i> passed below the beds provincially

-termed lias-clay and limestone&mdash;that these again passed underneath

-the sands, yellow limestone, and clays that form the

-table-land of the Coteswold Hills; while they in turn plunged

-beneath the great escarpment of chalk that runs from the coast

-of Dorsetshire northward to the Yorkshire shores of the German

-Ocean. He further observed that each formation of clay, sand,

-or limestone, held to a very great extent its own peculiar suite

-of fossils. The “snake-stones” (<i>Ammonites</i>) of the lias were

-different in form and ornament from those of the inferior oolite;

-and the shells of the latter, again, differed from those of the

-Oxford clay, Cornbrash, and Kimmeridge clay. Pondering

-much on these things, he came to the then unheard-of conclusion

-that each formation had been in its turn a sea-bottom,

-in the sediments of which lived and died marine animals now

-extinct, many specially distinctive of their own epochs in time.</p>

-

-<p>Here indeed was a discovery,&mdash;made, too, by a man utterly

-unknown to the scientific world, and having no pretension to

-scientific lore. “Strata Smith’s” find was unheeded for many

-a long year; but at length the first geologists of the day

-learned from the land-surveyor that superposition of strata

-is inseparably connected with the succession of life in time.

-Hooke’s grand vision was at length realised, and it was indeed

-possible “to build up a terrestrial chronology from rotten shells”

-imbedded in the rocks. Meanwhile he had constructed the

-first geological map of England, which has served as a basis for

-geological maps of all other parts of the world. William Smith

-was now presented by the Geological Society with the Wollaston

-Medal, and hailed as “the Father of English Geology.”<span class="pagenum"><a name="Page_127" id="Page_127">127</a></span>

-He died in 1840. Till the manner as well as the fact of the first

-appearance of successive forms of life shall be solved, it is not

-easy to surmise how any discovery can be made in geology

-equal in value to that which we owe to the genius of William

-Smith.&mdash;<i>Saturday Review</i>, No. 140.</p>

-

-<h3>DR. BUCKLAND’s GEOLOGICAL LABOURS.</h3>

-

-<p>Sir Henry De la Beche, in his Anniversary Address to the

-Geological Society in 1848, on presenting the Wollaston Medal

-to Dr. Buckland, felicitously observed:</p>

-

-<blockquote>

-

-<p>It may not be generally known that, while yet a child, at your

-native town, Axminster in Devonshire, ammonites, obtained by your

-father from the lime quarries in the neighbourhood, were presented to

-your attention. As a scholar at Winchester, the chalk, with its flints,

-was brought under your observation, and there it was that your collections

-in natural history first began. Removed to Oxford, as a scholar

-of Corpus Christi College, the future teacher of geology in that University

-was fortunate in meeting with congenial tastes in our colleague

-Mr. W.&nbsp;J. Broderip, then a student at Oriel College. It was during your

-walks together to Shotover Hill, when his knowledge of conchology was

-so valuable to you, enabling you to distinguish the shells of the Oxford

-oolite, that you laid the foundation for those field-lectures, forming part

-of your course of geology at Oxford, which no one is likely to forget who

-has been so fortunate at any time as to have attended them. The fruits

-of your walks with Mr. Broderip formed the nucleus of that great collection,

-more especially remarkable for the organic remains it contains,

-which, after the labours of forty years, you have presented to the Geological

-Museum at Oxford, in grave recollection of the aid which the

-endowments of that University, and the leisure of its vacations, had

-afforded you for extensive travelling during a residence at Oxford of

-nearly forty-five years.</p></blockquote>

-

-<h3 title="Discoveries of M. Agassiz.">DISCOVERIES OF M. AGASSIZ.<a name="FNanchor_34" id="FNanchor_34" href="#Footnote_34" class="fnanchor smaller">34</a></h3>

-

-<p>This great paleontologist, in the course of his ichthyological

-researches, was led to perceive that the arrangement by Cuvier

-according to organs did not fulfil its purpose with regard to

-fossil fishes, because in the lapse of ages the characteristics of

-their structures were destroyed. He therefore adopted the only

-other remaining plan, and studied the tissues, which, being

-less complex than the organs, are oftener found intact. The

-result was the very remarkable discovery, that the tegumentary

-membrane of fishes is so intimately connected with their organisation,

-that if the whole of the fish has perished except this

-membrane, it is practicable, by noting its characteristics, to reconstruct

-the animal in its most essential parts. Of the value

-of this principle of harmony, some idea may be formed from

-the circumstance, that on it Agassiz has based the whole of that<span class="pagenum"><a name="Page_128" id="Page_128">128</a></span>

-celebrated classification of which he is the sole author, and by

-which fossil ichthyology has for the first time assumed a precise

-and definite shape. How essential its study is to the geologist

-appears from the remark of Sir Roderick Murchison, that “fossil

-fishes have every where proved the most exact chronometer

-of the age of rocks.”</p>

-

-<h3>SUCCESSION OF LIFE IN TIME.</h3>

-

-<p>In the Museum of Economic Geology, in Jermyn Street, may

-be seen ores, metals, rocks, and whole suites of fossils stratigraphically

-arranged in such a manner that, with an observant

-eye for form, all may easily understand the more obvious scientific

-meanings of the Succession of Life in Time, and its bearing

-on geological economies. It is perhaps scarcely an exaggeration

-to say, that the greater number of so-called educated persons

-are still ignorant of the meaning of this great doctrine. They

-would be ashamed not to know that there are many suns and

-material worlds besides our own; but the science, equally grand

-and comprehensible, that aims at the discovery of the laws that

-regulated the creation, extension, decadence, and utter extinction

-of many successive species, genera, and whole orders of life,

-is ignored, or, if intruded on the attention, is looked on as an

-uncertain and dangerous dream,&mdash;and this in a country which

-was almost the nursery of geology, and which for half a century

-has boasted the first Geological Society in the world.&mdash;<i>Saturday

-Review</i>, No. 140.</p>

-

-<h3>PRIMITIVE DIVERSITY AND NUMBERS OF ANIMALS IN

-GEOLOGICAL TIMES.</h3>

-

-<p>Professor Agassiz considers that the very fact of certain stratified

-rocks, even among the oldest formations, being almost

-entirely made up of fragments of organised beings, should long

-ago have satisfied the most sceptical that both <i>animal and

-vegetable life were as active and profusely scattered upon the whole

-globe at all times, and during all geological periods, as they are

-now</i>. No coral reef in the Pacific contains a larger amount

-of organic <i>débris</i> than some of the limestone deposits of the

-tertiary, of the cretaceous, or of the oolitic, nay even of the

-paleozoic period; and the whole vegetable carpet covering the

-present surface of the globe, even if we were to consider only

-the luxuriant vegetation of the tropics, leaving entirely out of

-consideration the entire expanse of the ocean, as well as those

-tracts of land where, under less favourable circumstances, the

-growth of plants is more reduced,&mdash;would not form one single

-seam of workable coal to be compared to the many thick beds

-contained in the rocks of the carboniferous period alone.</p>

-

-<p><span class="pagenum"><a name="Page_129" id="Page_129">129</a></span></p>

-

-<h3>ENGLAND IN THE EOCENE PERIOD.</h3>

-

-<p>Eocene is Sir Charles Lyell’s term for the lowest group of

-the Tertiary system in which the dawn of recent life appears;

-and any one who wishes to realise what was the aspect presented

-by this country during the Eocene period, need only go

-to Sheerness. If, leaving that place behind him, he walks

-down the Thames, keeping close to the edge of the water, he

-will find whole bushels of pyritised pieces of twigs and fruits.

-These fruits and twigs belong to plants nearly allied to the

-screw-pine and custard-apple, and to various species of palms

-and spice-trees which now flourish in the Eastern Archipelago.

-At the time they were washed down from some neighbouring

-land, not only crocodilian reptiles, but sharks and innumerable

-turtles, inhabited a sea or estuary which now forms part of the

-London district; and huge boa-constrictors glided amongst the

-trees which fringed the adjoining shores.</p>

-

-<p>Countless as are the ages which intervened between the

-Eocene period and the time when the little jawbones of Stonesfield

-were washed down to the place where they were to await

-the day when science should bring them again to light, not one

-mammalian genus which now lives upon our plane has been

-discovered amongst Eocene strata. We have existing families,

-but nothing more.&mdash;<i>Professor Owen.</i></p>

-

-<h3>FOOD OF THE IGUANODON.</h3>

-

-<p>Dr. Mantell, from the examination of the anterior part of

-the right side of the lower jaw of an Iguanodon discovered in a

-quarry in Tilgate Forest, Sussex, has detected an extraordinary

-deviation from all known types of reptilian organisation, and

-which could not have been predicated; namely, that this colossal

-reptile, which equalled in bulk the gigantic Edentata of

-South America, and like them was destined to obtain support

-from comminuted vegetable substances, was also furnished with a

-large prehensile tongue and fleshy lips, to serve as instruments

-for seizing and cropping the foliage and branches of trees;

-while the arrangement of the teeth as in the ruminants, and

-their internal structure, which resembles that of the molars of

-the sloth tribe in the vascularity of the dentine, indicate adaptations

-for the same purpose.</p>

-

-<p>Among the physiological phenomena revealed by paleontology,

-there is not a more remarkable one than this modification

-of the type of organisation peculiar to the class of reptiles to

-meet the conditions required by the economy of a lizard placed

-under similar physical relations; and destined to effect the

-same general purpose in the scheme of nature as the colossal<span class="pagenum"><a name="Page_130" id="Page_130">130</a></span>

-Edentata of former ages and the large herbivorous mammalia

-of our own times.</p>

-

-<h3>THE PTERODACTYL&mdash;THE FLYING DRAGON.</h3>

-

-<p>The Tilgate beds of the Wealden series, just mentioned, have

-yielded numerous fragments of the most remarkable reptilian

-fossils yet discovered, and whose wonderful forms denote them

-to have thronged the shallow seas and bays and lagoons of the

-period. In the grounds of the Crystal Palace at Sydenham

-the reader will find restorations of these animals sufficiently

-perfect to illustrate this reptilian epoch. They include the <i>iguanodon</i>,

-an herbivorous lizard exceeding in size the largest elephant,

-and accompanied by the equally gigantic and carnivorous

-<i>megalosaurus</i> (great saurian), and by the two yet more

-curious reptiles, the <i>pylæosaurus</i> (forest, or weald, saurian) and

-the pterodactyl (from <i>pteron</i>, ‘wing,’ and <i>dactylus</i>, ‘a finger’),

-an enormous bat-like creature, now running upon the ground

-like a bird; its elevated body and long neck not covered with

-feathers, but with skin, naked, or resplendent with glittering

-scales; its head like that of a lizard or crocodile, and of a size

-almost preposterous compared with that of the body, with its

-long fore extremities stretched out, and connected by a membrane

-with the body and hind legs.</p>

-

-<p>Suddenly this mailed creature rose in the air, and realised

-or even surpassed in strangeness <i>the flying dragon of fable</i>: its

-fore-arms and its elongated wing-finger furnished with claws;

-hand and fingers extended, and the interspace filled up by a

-tough membrane; and its head and neck stretched out like

-that of the heron in its flight. When stationary, its wings

-were probably folded back like those of a bird; though perhaps,

-by the claws attached to its fingers, it might suspend itself from

-the branches of trees.</p>

-

-<h3>MAMMALIA IN SECONDARY ROCKS.</h3>

-

-<p>It was supposed till very lately that few if any Mammalia

-were to be found below the Tertiary rocks, <i>i. e.</i> those above the

-chalk; and this supposed fact was very comfortable to those

-who support the doctrine of “progressive development,” and

-hold, with the notorious <i>Vestiges of Creation</i>, that a fish by

-mere length of time became a reptile, a lemur an ape, and

-finally an ape a man. But here, as in a hundred other cases,

-facts, when duly investigated, are against their theory. A

-mammal jaw had been already discovered by Mr. Brodie on

-the shore at the back of Swanage Point, in Dorsetshire, when

-Mr. Beckles, F.G.S., traced the vein from which this jaw had

-been procured, and found it to be a stratum about five inches<span class="pagenum"><a name="Page_131" id="Page_131">131</a></span>

-thick, at the base of the Middle Purbeck beds; and after removing

-many thousand tons of rock, and laying bare an area of

-nearly 7000 square feet (the largest cutting ever made for purely

-scientific purposes), he found reptiles (tortoises and lizards) in

-hundreds; but the most important discovery was that of the

-jaws of at least fourteen different species of mammalia. Some

-of these were herbivorous, some carnivorous, connected with

-our modern shrews, moles, hedgehogs, &amp;c.; but all of them perfectly

-developed and highly-organised quadrupeds. Ten years

-ago, no remains of quadrupeds were believed to exist in the

-Secondary strata. “Even in 1854,” says Sir Charles Lyell (in

-a supplement to the fifth edition of his <i>Manual of Elementary

-Geology</i>), “only six species of mammals from rocks older than

-the Tertiary were known in the whole world.” We now possess

-evidence of the existence of fourteen species, belonging to eight

-or nine genera, from the fresh-water strata of the Middle Purbeck

-Oolite. It would be rash now to fix a limit in past time

-to the existence of quadrupeds.&mdash;<i>The Rev. C. Kingsley.</i></p>

-

-<h3>FOSSIL HUMAN BONES.</h3>

-

-<p>In the paleontological collection in the British Museum is

-preserved a considerable portion of a human skeleton imbedded

-in a slab of rock, brought from Guadaloupe, and often referred

-to in opposition to the statement that hitherto <i>no fossil human

-hones have been found</i>. The presence of these bones, however,

-has been explained by the circumstance of a battle and the

-massacre of a tribe of Galtibis by the Caribs, which took place

-near the spot in which the bones were found about 130 years

-ago; for as the bodies of the slain were interred on the seashore,

-their skeletons may have been subsequently covered by

-sand-drift, which has since consolidated into limestone.</p>

-

-<p>It will be seen by reference to the <i>Philosophical Transactions</i>,

-that on the reading of the paper upon this discovery to

-the Royal Society, in 1814, Sir Joseph Banks, the president,

-considered the “fossil” to be of very modern formation, and

-that probably, from the contiguity of a volcano, the temperature

-of the water may have been raised at some time, and dissolving

-carbonate of lime readily, may have deposited about

-the skeleton in a comparatively short period hard and solid

-stone. Every person may be convinced of the rapidity of the

-formation and of the hardness of such stone by inspecting the

-inside of tea-kettles in which hard water is boiled.</p>

-

-<blockquote>

-

-<p>Descriptions of petrifactions of human bodies appear to refer to the

-conversion of bodies into adipocere, and not into stone. All the supposed

-cases of petrifaction are probably of this nature. The change

-occurs only when the coffin becomes filled with water. The body, converted

-into adipocere, floats on the water. The supposed cases of<span class="pagenum"><a name="Page_132" id="Page_132">132</a></span>

-changes of position in the grave, bursting open the coffin-lids, turning

-over, crossing of limbs, &amp;c., formerly attributed to the coming to life of

-persons buried who were not dead, is now ascertained to be due to the

-same cause. The chemical change into adipocere, and the evolution of

-gases, produce these movements of dead bodies.&mdash;<i>Mr. Trail Green.</i></p></blockquote>

-

-<h3>THE MOST ANCIENT FISHES.</h3>

-

-<p>Among the important results of Sir Roderick Murchison’s

-establishment of the Silurian system is the following:</p>

-

-<blockquote>

-

-<p>That as the Lower Silurian group, often of vast dimensions, has

-never afforded the smallest vestige of a Fish, though it abounds in numerous

-species of the <i>marine</i> classes,&mdash;corals, <i>crinoidea</i>, <i>mollusca</i>, and

-<i>crustacea</i>; and as in Scandinavia and Russia, where it is based on rocks

-void of fossils, its lowest stratum contains <i>fucoids</i> only,&mdash;Sir R. Murchison

-has, after fifteen years of laborious research steadily directed to

-this point, arrived at the conclusion, that a very long period elapsed

-after life was breathed into the waters before the lowest order of vertebrata

-was created; the earliest fishes being those of the Upper Silurian

-rocks, which he was the first to discover, and which he described “as

-the most ancient beings of their class which have yet been brought to

-light.” Though the Lower Silurian rocks of various parts of the world

-have since been ransacked by multitudes of prying geologists, who have

-exhumed from them myriads of marine fossils, not a single ichthyolite

-has been found in any stratum of higher antiquity than the Upper

-Silurian group of Murchison.</p></blockquote>

-

-<p>The most remarkable of all fossil fishes yet discovered have

-been found in the Old Red Sandstone cliffs at Dorpat, where

-the remains are so gigantic (one bone measuring <i>two feet nine

-inches</i> in length) that they were at first supposed to belong to

-saurians.</p>

-

-<p>Sir Roderick’s examination of Russia has, in short, proved

-that <i>the ichthyolites and mollusks which, in Western Europe, are

-separately peculiar to smaller detached basins, were here (in the

-British Isles) cohabitants of many parts of the same great sea</i>.</p>

-

-<h3>EXTINCT CARNIVOROUS ANIMALS OF BRITAIN.</h3>

-

-<p>Professor Owen has thus forcibly illustrated the Carnivorous

-Animals which preyed upon and restrained the undue multiplication

-of the vegetable feeders. First we have the bear

-family, which is now represented in this country only by the

-badger. We were once blest, however, with many bears. One

-species seems to have been identical with the existing brown

-bear of the European continent. Far larger and more formidable

-was the gigantic cave-bear (<i>Ursus spelæus</i>), which surpassed in

-size his grisly brother of North America. The skull of the cave-bear

-differs very much in shape from that of its small brown

-relative just alluded to; the forehead, in particular, is much

-higher,&mdash;to be accounted for by an arrangement of air-cells similar

-to those which we have already remarked in the elephant.<span class="pagenum"><a name="Page_133" id="Page_133">133</a></span>

-The cave-bear has left its remains in vast abundance in Germany.

-In our own caves, the bones of hyænas are found in

-greater quantities. The marks which the teeth of the hyæna

-make upon the bones which it gnaws are quite unmistakable.

-Our English hyænas had the most undiscriminating appetite,

-preying upon every creature, their own species amongst others.

-Wolves, not distinguishable from those which now exist in

-France and Germany, seem to have kept company with the

-hyænas; and the <i>Felis spelæa</i>, a sort of lion, but larger than

-any which now exists, ruled over all weaker brutes. Here,

-says Professor Owen, we have the original British Lion. A

-species of <i>Machairodus</i> has left its remains at Kent’s Hole, near

-Torquay. In England we had also the beaver, which still

-lingers on the Danube and the Rhone, and a larger species,

-which has been called Trogontherium (gnawing beast), and a

-gigantic mole.</p>

-

-<h3>THE GREAT CAVE TIGER OR LION OF BRITAIN.</h3>

-

-<p>Remains of this remarkable animal of the drift or gravel

-period of this country have been found at Brentford and elsewhere

-near London. Speaking of this animal, Professor Owen

-observes, that “it is commonly supposed that the Lion, the

-Tiger, and the Jaguar are animals peculiarly adapted to a

-tropical climate. The genus Felis (to which these animals

-belong) is, however, represented by specimens in high northern

-latitudes, and in all the intermediate countries to the equator.”

-The chief condition necessary for the presence of such animals

-is an abundance of the vegetable-feeding animals. It is thus

-that the Indian tiger has been known to follow the herds of

-antelope and deer in the lofty mountains of the Himalaya to the

-verge of perpetual snow, and far into Siberia. “It need not,

-therefore,” continues Professor Owen, “excite surprise that

-indications should have been discovered in the fossil relics of

-the ancient mammalian population of Europe of a large feline

-animal, the contemporary of the mammoth, of the tichorrhine

-rhinoceros, of the great gigantic cave-bear and hyæna, and the

-slayer of the oxen, deer, and equine quadrupeds that so

-abounded during the same epoch.” The dimensions of this

-extinct animal equal those of the largest African lion or Bengal

-tiger; and some bones have been found which seem to imply

-that it had even more powerful limbs and larger paws.</p>

-

-<h3>THE MAMMOTHS OF THE BRITISH ISLES.</h3>

-

-<p>Dr. Buckland has shown that for long ages many species

-of carnivorous animals now extinct inhabited the caves of the

-British islands. In low tracts of Yorkshire, where tranquil

-lacustrine (lake-like) deposits have occurred, bones (even those<span class="pagenum"><a name="Page_134" id="Page_134">134</a></span>

-of the lion) have been found so perfectly unbroken and unworn,

-in fine gravel (as at Market Weighton), that few persons

-would be disposed to deny that such feline and other animals

-once roamed over the British isles, as well as other European

-countries. Why, then, is it improbable that large elephants,

-with a peculiarly thick integument, a close coating of wool,

-and much long shaggy hair, should have been the occupants

-of wide tracts of Northern Europe and Asia? This coating,

-Dr. Fleming has well remarked, was probably as impenetrable

-to rain and cold as that of the monster ox of the polar circle.

-Such is the opinion of Sir Roderick Murchison, who thus accounts

-for the disappearance of the mammoths from Britain:</p>

-

-<blockquote>

-

-<p>When we turn from the great Siberian continent, which, anterior to

-its elevation, was the chief abode of the mammoths, and look to the

-other parts of Europe, where their remains also occur, how remarkable

-is it that we find the number of these creatures to be justly proportionate

-to the magnitude of the ancient masses of land which the labours

-of geologists have defined! Take the British isles, for example, and let

-all their low, recently elevated districts be submerged; let, in short,

-England be viewed as the comparatively small island she was when the

-ancient estuary of the Thames, including the plains of Hyde Park,

-Chelsea, Hounslow, and Uxbridge, were under the water; when the

-Severn extended far into the heart of the kingdom, and large eastern

-tracts of the island were submerged,&mdash;and there will then remain but

-moderately-sized feeding-grounds for the great quadrupeds whose bones

-are found in the gravel of the adjacent rivers and estuaries.</p></blockquote>

-

-<p>This limited area of subsistence could necessarily only keep

-up a small stock of such animals; and, just as we might expect,

-the remains of British mammoths occur in very small

-numbers indeed, when compared with those of the great charnel-houses

-of Siberia, into which their bones had been carried

-down through countless ages from the largest mass of surface

-which geological inquiries have yet shown to have been <i>dry

-land</i> during that epoch.</p>

-

-<p>The remains of the mammoth, says Professor Owen, have

-been found in all, or almost all, the counties of England. Off

-the coast of Norfolk they are met with in vast abundance.

-The fishermen who go to catch turbot between the mouth of

-the Thames and the Dutch coast constantly get their nets entangled

-in the tusks of the mammoth. A collection of tusks

-and other remains, obtained in this way, is to be seen at Ramsgate.

-In North America, this gigantic extinct elephant must

-have been very common; and a large portion of the ivory

-which supplies the markets of Europe is derived from the vast

-mammoth graveyards of Siberia.</p>

-

-<p>The mammoth ranged at least as far north as 60°. There

-is no doubt that, at the present day, many specimens of the

-musk-ox are annually becoming imbedded in the mud and ice

-of the North-American rivers.</p>

-

-<p><span class="pagenum"><a name="Page_135" id="Page_135">135</a></span>

-It is curious to observe, that the mammoth teeth which are

-met with in caves generally belonged to young mammoths, who

-probably resorted thither for shelter before increasing age and

-strength emboldened them to wander far afield.</p>

-

-<h3>THE RHINOCEROS AND HIPPOPOTAMUS OF ENGLAND.</h3>

-

-<p>The mammoth was not the only giant that inhabited England

-in the Pliocene or Upper Tertiary period. We had also

-here the <i>Rhinoceros tichorrhinus</i>, or “strongly walled about the

-nose,” remains of which have been discovered in enormous

-quantities in the brickfields about London. Pallas describes

-an entire specimen of this creature, which was found near

-Yakutsk, the coldest town on the globe. Another rhinoceros,

-<i>leptorrhinus</i> (fine nose), dwelt with the elephant of Southern

-Europe. In Siberia has been discovered the Elaimotherium,

-forming a link between the rhinoceros and the horse.</p>

-

-<p>In the days of the mammoth, we had also in England a

-Hippopotamus, rather larger than the species which now inhabits

-the Nile. Of our British hippopotamus some remains

-were dug up by the workmen in preparing the foundations of

-the New Junior United Service Club-house, in Regent-street.</p>

-

-<h3>THE ELEPHANT AND TORTOISE.</h3>

-

-<p>The idea of an Elephant standing on the back of a Tortoise

-was often laughed at as an absurdity, until Captain Cautley

-and Dr. Falconer at length discovered in the hills of Asia the

-remains of a tortoise in a fossil state of such a size that an

-elephant could easily have performed the above feat.</p>

-

-<h3>COEXISTENCE OF MAN AND THE MASTODON.</h3>

-

-<p>Dr. C. F. Winslow has communicated to the Boston Society

-of Natural History the discovery of the fragment of a human

-cranium 180 feet below the surface of the Table Mountain,

-California. Now the mastodon’s bones being found in the

-same deposits, points very clearly to the probability of the appearance

-of the human race on the western portions of North

-America at least before the extinction of those huge creatures.

-Fragments of mastodon and <i>Elephas primigenius</i> have been

-taken ten and twenty feet below the surface in the above locality;

-where this discovery of human and mastodon remains

-gives strength to the possible truth of an old Indian tradition,&mdash;the

-contemporary existence of the mammoth and aboriginals

-in this region of the globe.</p>

-

-<h3>HABITS OF THE MEGATHERIUM.</h3>

-

-<p>Much uncertainty has been felt about the habits of the Megatherium,

-or Great Beast. It has been asked whether it burrowed<span class="pagenum"><a name="Page_136" id="Page_136">136</a></span>

-or climbed, or what it did; and difficulties have presented

-themselves on all sides of the question. Some have

-thought that it lived in trees as much larger than those which

-now exist as the Megatherium itself is larger than the common

-sloth.<a name="FNanchor_35" id="FNanchor_35" href="#Footnote_35" class="fnanchor">35</a> This, however, is now known to be a mistake. It did

-not climb trees&mdash;it pulled them down; and in order to do this

-the hinder parts of its skeleton were made enormously strong,

-and its prehensile fore-legs formed so as to give it a tremendous

-power over any thing which it grasped. Dr. Buckland suggested

-that animals which got their living in this way had

-a very fair chance of having their heads broken. While Professor

-Owen was still pondering over this difficulty, the skull

-of a cognate animal, the Mylodon, came into his hands. Great

-was his delight when he found that the mylodon not only had

-his head broken, but broken in two different places, at two

-different times; and moreover so broken that the injury could

-only have been inflicted by some such agent as a fallen tree.

-The creature had recovered from the first blow, but had evidently

-died of the second. This tribe had, as it turns out,

-two skulls, an outer and an inner one&mdash;given them, as it

-would appear, expressly with a view to the very dangerous

-method in which they were intended to obtain their necessary

-food.</p>

-

-<p>The dentition of the megatherium is curious. The elephant

-gets teeth as he wants them. Nature provided for the

-comfort of the megatherium in another way. It did not get

-new teeth, but the old ones went on for ever growing as long

-as the animal lived; so that as fast as one grinding surface became

-useless, another supplied its place.</p>

-

-<h3>THE DINOTHERIUM, OR TERRIBLE BEAST.</h3>

-

-<p>The family of herbivorous Cetaceans are connected with the

-Pachydermata of the land by one of the most wonderful of all

-the extinct creatures with which geologists have made us acquainted.

-This is the <i>Dinotherium</i>, or Terrible Beast. The remains

-of this animal were found in Miocene sands at Eppelsheim,

-about forty miles from Darmstadt. It must have been

-larger than the largest extinct or living elephant. The most

-remarkable peculiarity of its structure is the enormous tusks,

-curving downwards and terminating its lower jaw. It appears

-to have lived in the water, where the immense weight of these

-formidable appendages would not be so inconvenient as on

-land. What these tusks were used for is a mystery; but perhaps

-they acted as pickaxes in digging up trees and shrubs, or as<span class="pagenum"><a name="Page_137" id="Page_137">137</a></span>

-harrows in raking the bottom of the water. Dr. Buckland used

-to suggest that they were perhaps employed as anchors, by

-means of which the monster might fasten itself to the bank of

-a stream and enjoy a comfortable nap. The extreme length of

-the <i>Dinotherium</i> was about eighteen feet. Professor Kemp, in

-his restoration of the animal, has given it a trunk like that of

-the elephant, but not so long, and the general form of the tapir.&mdash;<i>Professor

-Owen.</i></p>

-

-<h3>THE GLYPTODON.</h3>

-

-<p>There are few creatures which we should less have expected

-to find represented in fossil history by a race of gigantic brethren

-than the armadillo. The creature is so small, not only in size

-but in all its works and ways, that we with difficulty associate

-it with the idea of magnitude. Yet Sir Woodbine Parish has

-discovered evidences of enormous animals of this family having

-once dwelt in South America. The huge loricated (plated over)

-creature whose relics were first sent has received the name of

-Glyptodon, from its sculptured teeth. Unlike the small armadillos,

-it was unable to roll itself up into a ball; though an

-enormous carnivore which lived in those days must have made

-it sometimes wish it had the power to do so. When attacked,

-it must have crouched down, and endeavoured to make its huge

-shell as good a defence as possible.&mdash;<i>Professor Owen.</i></p>

-

-<h3>INMATES OF AN AUSTRALIAN CAVERN.</h3>

-

-<p>From the fossil-bone caverns in Wellington Valley, in 1830,

-were sent to Professor Owen several bones which belonged, as

-it turned out, to gigantic kangaroos, immensely larger than

-any existing species; to a kind of wombat, to formidable dasyures,

-and several other genera. It also appeared that the

-bones, which were those of herbivores, had evidently belonged

-to young animals, while those of the carnivores were full-sized;

-a fact which points to the relations between the two families

-having been any thing but agreeable to the herbivores.</p>

-

-<h3>THE POUCH-LION OF AUSTRALIA.</h3>

-

-<p>The <i>Thylacoleo</i> (Pouch-Lion) was a gigantic marsupial carnivore,

-whose character and affinities Professor Owen has, with

-exquisite scientific tact, made out from very small indications.

-This monster, which had kangaroos with heads three feet long

-to feed on, must have been one of the most extraordinary animals

-of the antique world.</p>

-

-<h3>THE CONEY OF SCRIPTURE.</h3>

-

-<p>Paleontologists have pointed out the curious fact that the<span class="pagenum"><a name="Page_138" id="Page_138">138</a></span>

-Hyrax, called ‘coney’ in our authorised version of the Bible, is

-really only a diminutive and hornless rhinoceros. Remains have

-been found at Eppelsheim which indicate an animal more like a

-gigantic Hyrax than any of the existing rhinoceroses. To this

-the name of <i>Acerotherium</i> (Hornless Beast) has been given.</p>

-

-<h3>A THREE-HOOFED HORSE.</h3>

-

-<p>Professor Owen describes the <i>Hipparion</i>, or Three-hoofed

-Horse, as the first representative of a family so useful to mankind.

-This animal, in addition to its true hoof, appears to

-have had two additional elementary hoofs, analogous to those

-which we see in the ox. The object of these no doubt was to

-enable the Hipparion to extricate his foot with greater ease

-than he otherwise could when it sank through the swampy

-ground on which he lived.</p>

-

-<h3>TWO MONSTER CARNIVORES OF FRANCE.</h3>

-

-<p>A huge carnivorous creature has been found in Miocene

-strata in France, in which country it preyed upon the gazelle

-and antelope. It must have been as large as a grisly bear, but

-in general appearance and teeth more like a gigantic dog.

-Hence the name of <i>Amphicyon</i> (Doubtful Dog) has been assigned

-to it. This animal must have derived part of its support

-from vegetables. Not so the coeval monster which has been

-called <i>Machairodus</i> (Sabre-tooth). It must have been somewhat

-akin to the tiger, and is by far the most formidable animal

-which we have met with in our ascending progress through

-the extinct mammalia.&mdash;<i>Professor Owen.</i></p>

-

-<h3>GEOLOGY OF THE SHEEP.</h3>

-

-<p>No unequivocal fossil remains of the sheep have yet been

-found in the bone-caves, the drift, or the more tranquil stratified

-newer Pliocene deposits, so associated with the fossil bones

-of oxen, wild-boars, wolves, foxes, otters, &amp;c., as to indicate

-the coevality of the sheep with those species, or in such an

-altered state as to indicate them to have been of equal antiquity.

-Professor Owen had his attention particularly directed

-to this point in collecting evidence for a history of British

-Fossil Mammalia. No fossil core-horns of the sheep have yet

-been any where discovered; and so far as this negative evidence

-goes, we may infer that the sheep is not geologically

-more ancient than man; that it is not a native of Europe, but

-has been introduced by the tribes who carried hither the germs

-of civilisation in their migrations westward from Asia.</p>

-

-<h3>THE TRILOBITE.</h3>

-

-<p>Among the earliest races we have those remarkable forms,<span class="pagenum"><a name="Page_139" id="Page_139">139</a></span>

-the Trilobites, inhabiting the ancient ocean. These crustacea

-remotely resemble the common wood-louse, and like that animal

-they had the power of rolling themselves into a ball when

-attacked by an enemy. The eye of the trilobite is a most remarkable

-organ; and in that of one species, <i>Phacops caudatus</i>,

-not less than 250 lenses have been discovered. This remarkable

-optical instrument indicates that these creatures lived

-under similar conditions to those which surround the crustacea

-of the present day.&mdash;<i>Hunt’s Poetry of Science.</i></p>

-

-<h3>PROFITABLE SCIENCE.</h3>

-

-<p>In that strip of reddish colour which runs along the cliffs

-of Suffolk, and is called the Redcrag, immense quantities of

-cetacean remains have been found. Four different kinds of

-whales, little inferior in size to the whalebone whale, have left

-their bones in this vast charnel-house. In 1840, a singularly

-perplexing fossil was brought to Professor Owen from this Redcrag.

-No one could say what it was. He determined it to be

-the tooth of a cetacean, a unique specimen. Now the remains

-of cetaceans in the Suffolk crag have been discovered in such

-enormous quantities, that many thousands a-year are made by

-converting them into manure.</p>

-

-<h3>EXTINCT GIGANTIC BIRDS OF NEW ZEALAND.</h3>

-

-<p>In the islands of New Zealand have been found the bones of

-large extinct wingless Birds, belonging to the Post Tertiary or

-Recent system, which have been deposited by the action of rivers.

-The bird is named <i>Moa</i> by the natives, and <i>Dinornis</i> by naturalists:

-some of the bones have been found in two caves in the

-North Island, and have been sold by the natives at an extraordinary

-price. The caves occur in limestone rocks, and the bones

-are found beneath earth and a soft deposit of carbonate of lime.

-The largest of the birds is stated to have stood thirteen or fourteen

-feet, or twice the height of the ostrich; and its egg large

-enough to fill the hat of a man as a cup. Several statements

-have appeared of these birds being still in existence, but there

-is every reason to believe the Moa to be altogether extinct.</p>

-

-<p>An extensive collection of remains of these great wingless

-birds has been collected in New Zealand by Mr. Walter Mantell,

-and deposited in the British Museum. Among these bones

-Professor Owen has discovered a species which he regards as

-the most remarkable of the feathered class for its prodigious

-strength and massive proportions, and which he names <i>Dinornis

-elephantopus</i>, or elephant-footed, of which the Professor has

-been able to construct an entire lower limb: the length of the

-metatarsal bone is 9¼ inches, the breadth of the lower end<span class="pagenum"><a name="Page_140" id="Page_140">140</a></span>

-being 5-1/3 inches. The extraordinary proportions of the metatarsus

-of this wingless bird will, however, be still better understood

-by comparison with the same bone in the ostrich, in

-which the metatarsus is 19 inches in length, the breadth of its

-lower end being only 2½ inches. From the materials accumulated

-by Mr. Mantell, the entire skeleton of the <i>Dinornis elephantopus</i>

-has been reconstructed; and now forms a worthy

-companion of the Megatherium and Mastodon in the gallery of

-fossil remains in the British Museum. This species of <i>Dinornis</i>

-appears to have been restricted to the Middle Island of New

-Zealand.<a name="FNanchor_36" id="FNanchor_36" href="#Footnote_36" class="fnanchor">36</a></p>

-

-<p>Another specimen of the remains of the <i>Dinornis</i> is preserved

-in the Museum of the Royal College of Surgeons, in

-Lincoln’s-Inn Fields; and the means by which the college

-obtained this valuable acquisition is thus graphically narrated

-by Mr. Samuel Warren, F.R.S.:</p>

-

-<blockquote>

-

-<p>In the year 1839, Professor Owen was sitting alone in his study, when

-a shabbily-dressed man made his appearance, announcing that he had

-got a great curiosity, which he had brought from New Zealand, and

-wished to dispose of to him. It had the appearance of an old marrow-bone,

-about six inches in length, and rather more than two inches

-in thickness, <i>with both extremities broken off</i>; and Professor Owen considered

-that, to whatever animal it might have belonged, the fragment

-must have lain in the earth for centuries. At first he considered this

-same marrow-bone to have belonged to an ox, at all events to a quadruped;

-for the wall or rim of the bone was six times as thick as the bone

-of any bird, even of the ostrich. He compared it with the bones in the

-skeleton of an ox, a horse, a camel, a tapir, and every quadruped apparently

-possessing a bone of that size and configuration; but it corresponded

-with none. On this he very narrowly examined the surface of

-the bony rim, and at length became satisfied that this fragment must

-have belonged to <i>a bird</i>!&mdash;to one at least as large as an ostrich, but of

-a totally different species; and consequently one never before heard of,

-as an ostrich was by far the biggest bird known.</p>

-

-<p>From the difference in the <i>strength</i> of the bone, the ostrich being unable

-to fly, so must have been unable this unknown bird; and so our

-anatomist came to the conclusion that this old shapeless bone indicated

-the former existence in New Zealand of some huge bird, at least as

-great as an ostrich, but of a far heavier and more sluggish kind. Professor

-Owen was confident of the validity of his conclusions, but would

-communicate that confidence to no one else; and notwithstanding attempts

-to dissuade him from committing his views to the public, he

-printed his deductions in the <i>Transactions of the Zoological Society for

-1839</i>, where fortunately they remain on record as conclusive evidence of

-the fact of his having then made this guess, so to speak, in the dark.

-He caused the bone, however, to be engraved; and having sent a hundred<span class="pagenum"><a name="Page_141" id="Page_141">141</a></span>

-copies of the engraving to New Zealand, in the hope of their being

-distributed and leading to interesting results, he patiently waited for

-three years,&mdash;viz. till the year 1842,&mdash;when he received intelligence

-from Dr. Buckland, at Oxford, that a great box, just arrived from New

-Zealand, consigned to himself, was on its way, unopened, to Professor

-Owen, who found it filled with bones, palpably of a bird, one of which

-bones was three feet in length, and much more than double the size of

-any bone in the ostrich!</p>

-

-<p>And out of the contents of this box the Professor was positively enabled

-to articulate almost the entire skeleton of a huge wingless bird

-between <span class="smcap smaller">TEN</span> and <span class="smcap smaller">ELEVEN</span> feet in height, its bony structure in strict conformity

-with the fragment in question; and that skeleton may at any

-time be seen at the Museum of the College of Surgeons, towering over,

-and nearly twice the height of, the skeleton of an ostrich; and at its feet

-lying the old bone from which alone consummate anatomical science had

-deduced such an astounding reality,&mdash;the existence of an enormous extinct

-creature of the bird kind, in an island where previously no bird

-had been known to exist larger than a pheasant or a common fowl!&mdash;<i>Lecture

-on the Moral and Intellectual Development of the present Age.</i><a name="FNanchor_37" id="FNanchor_37" href="#Footnote_37" class="fnanchor">37</a></p></blockquote>

-

-<h3>“THE MAESTRICHT SAURIAN FOSSIL” A FRAUD.</h3>

-

-<p>In 1795, there was stated to have been discovered in the

-stone quarries adjoining Maestricht the remains of the gigantic

-<i>Mosœsaurus</i> (Saurian of the Meuse), an aquatic reptile about

-twenty-five feet long, holding an intermediate place between

-the Monitors and Iguanas. It appears to have had webbed feet,

-and a tail of such construction as to have served for a powerful

-oar, and enabled the animal to stem the waves of the ocean, of

-which Cuvier supposed it to have been an inhabitant. It is

-thus referred to by Dr. Mantell, in his <i>Medals of Creation</i>: “A

-specimen, with the jaws and bones of the palate, now in the

-Museum at Paris, has long been celebrated; and is still the most

-precious relic of this extinct reptile hitherto discovered.” An

-admirable cast of this specimen is preserved in the British Museum,

-in a case near the bones of the Iguanodon. This is, however,

-useless, as Cuvier is proved to have been imposed upon in

-the matter.</p>

-

-<blockquote>

-

-<p>M. Schlegel has reported to the French Academy of Sciences, that

-he has ascertained beyond all doubt that the famous fossil saurian of

-the quarries of Maestricht, described as a wonderful curiosity by Cuvier,

-is nothing more than an impudent fraud. Some bold impostor, it seems,

-in order to make money, placed a quantity of bones in the quarries in

-such a way as to give them the appearance of having been recently dug

-up, and then passed them off as specimens of antediluvian creation.

-Being successful in this, he went the length of arranging a number of

-bones so as to represent an entire skeleton; and had thus deceived the<span class="pagenum"><a name="Page_142" id="Page_142">142</a></span>

-learned Cuvier. In extenuation of Cuvier’s credulity, it is stated that

-the bones were so skilfully coloured as to make them look of immense

-antiquity, and he was not allowed to touch them lest they should crumble

-to pieces. But when M. Schlegel subjected them to rude handling, he

-found that they were comparatively modern, and that they were placed

-one by the other without that profound knowledge of anatomy which

-was to have been expected from the man bold enough to execute such

-an audacious fraud.</p></blockquote>

-

-<h3>“THE OLDEST PIECE OF WOOD UPON EARTH.”</h3>

-

-<p>The most remarkable vegetable relic which the Lower Old

-Red Sandstone has given us is a small fragment of a coniferous

-tree of the Araucarian family, which formed one of the chief

-ornaments of the late Hugh Miller’s museum, and to which he

-used to point as the oldest piece of wood upon earth. He found

-it in one of the ichthyolite beds of Cromarty, and thus refers to

-it in his <i>Testimony of the Rocks</i>:</p>

-

-<blockquote>

-

-<p>On what perished land of the early paleozoic ages did this venerably

-antique tree cast root and flourish, when the extinct genera Pterichthys

-and Coccoeteus were enjoying life by millions in the surrounding seas,

-long ere the flora or fauna of the coal measures had begun to be?</p>

-

-<p>The same nodule which enclosed this lignite contained part of another

-fossil, the well-marked scales of <i>Diplacanthus striatus</i>, an ichthyolite restricted

-to the Lower Old Red Sandstone exclusively. If there be any

-value in paleontological evidence, this Cromarty lignite must have been

-deposited in a sea inhabited by the Coccoeteus and Diplacanthus. It

-is demonstrable that, while yet in a recent state, a Diplacanthus lay down

-and died beside it; and the evidence in the case is unequivocally this,

-that in the oldest portion of the oldest terrestrial flora yet known there

-occurs the fragment of a tree quite as high in the scale as the stately

-Norfolk-Island pine or the noble cedar of Lebanon.</p></blockquote>

-

-<h3>NO FOSSIL ROSE.</h3>

-

-<p>Professor Agassiz, in a lecture upon the trees of America,

-states a remarkable fact in regard to the family of the rose,&mdash;which

-includes among its varieties not only many of the

-most beautiful flowers, but also the richest fruits, as the apple,

-pear, peach, plum, apricot, cherry, strawberry, raspberry, &amp;c.,&mdash;namely,

-that <i>no fossil plants belonging to this family have ever

-been discovered by geologists</i>! This M. Agassiz regards as conclusive

-evidence that the introduction of this family of plants

-upon the earth was coeval with, or subsequent to, the creation

-of man, to whose comfort and happiness they seem especially

-designed by a wise Providence to contribute.</p>

-

-<h3>CHANGES ON THE EARTH’S SURFACE.</h3>

-

-<p>In the Imperial Library at Paris is preserved a manuscript

-work by an Arabian writer, Mohammed Karurini, who flourished

-in the seventh century of the Hegira, or at the close of the

-thirteenth century of our era. Herein we find several curious<span class="pagenum"><a name="Page_143" id="Page_143">143</a></span>

-remarks on aerolites and earthquakes, and the successive

-changes of position which the land and sea have undergone.

-Of the latter class is the following beautiful passage from the

-narrative of Khidz, an allegorical personage:</p>

-

-<blockquote>

-

-<p>I passed one day by a very ancient and wonderfully populous city,

-and asked one of its inhabitants how long it had been founded. “It is

-indeed a mighty city,” replied he; “we know not how long it has existed,

-and our ancestors were on this subject as ignorant as ourselves.”

-Five centuries afterwards, as I passed by the same place, I could not

-perceive the slightest vestige of the city. I demanded of a peasant who

-was gathering herbs upon its former site how long it had been destroyed.

-“In sooth, a strange question,” replied he; “the ground here has never

-been different from what you now behold it.” “Was there not of old,”

-said I, “a splendid city here?” “Never,” answered he, “so far as we

-have seen; and never did our fathers speak to us of any such.” On my

-return there five hundred years afterwards, <i>I found the sea in the same

-place</i>; and on its shores were a party of fishermen, of whom I inquired

-how long the land had been covered by the waters. “Is this a question,”

-say they, “for a man like you? This spot has always been what it is

-now.” I again returned five hundred years afterwards; the sea had

-disappeared: I inquired of a man who stood alone upon the spot how

-long this change had taken place, and he gave me the same answer as

-I had received before. Lastly, on coming back again after an equal

-lapse of time, I found there a flourishing city, more populous and more

-rich in beautiful buildings than the city I had seen the first time; and

-when I would fain have informed myself concerning its origin, the inhabitants

-answered me, “Its rise is lost in remote antiquity: we are

-ignorant how long it has existed, and our fathers were on this subject

-as ignorant as ourselves.”</p></blockquote>

-

-<p class="in0">This striking passage was quoted in the <i>Examiner</i>, in 1834.

-Surely in this fragment of antiquity we trace the “geological

-changes” of modern science.</p>

-

-<h3>GEOLOGICAL TIME.</h3>

-

-<p>Many ingenious calculations have been made to approximate

-the dates of certain geological events; but these, it must

-be confessed, are more amusing than instructive. For example,

-so many inches of silt are yearly laid down in the delta of the

-Mississippi&mdash;how many centuries will it have taken to accumulate

-a thickness of 30, 60, or 100 feet? Again, the ledges

-of Niagara are wasting at the rate of so many feet per century&mdash;how

-many years must the river have taken to cut its way

-back from Queenstown to the present Falls? Again, lavas

-and melted basalts cool, according to the size of the mass, at

-the rate of so many degrees in a given time&mdash;how many millions

-of years must have elapsed, supposing an original igneous

-condition of the earth, before its crust had attained a state of

-solidity? or further, before its surface had cooled down to the

-present mean temperature? For these and similar computations,

-the student will at once perceive we want the necessary<span class="pagenum"><a name="Page_144" id="Page_144">144</a></span>

-uniformity of factor; and until we can bring elements of calculation

-as exact as those of astronomy to bear on geological

-chronology, it will be better to regard our “eras” and “epochs”

-and “systems” as so many terms, indefinite in their duration,

-but sufficient for the magnitude of the operations embraced

-within their limits.&mdash;<i>Advanced Textbook of Geology, by David

-Page, F.G.S.</i></p>

-

-<p>M. Rozet, in 1841, called attention to the fact, that the

-causes which have produced irregularities in the structure of

-the globe have not yet ceased to act, as is proved by earthquakes,

-volcanic eruptions, slow and continuous movements

-of the crust of the earth in certain regions, &amp;c. We may,

-therefore, yet see repeated the great catastrophes which the

-surface of the earth has undergone anteriorly to the historical

-period.</p>

-

-<p>At the meeting of the British Association in 1855, Mr. Hopkins

-excited much controversy by his startling speculation&mdash;that

-9000 years ago the site on which London now stands was

-in the torrid zone; and that, according to perpetual changes

-in progress, the whole of England would in time arrive within

-the Arctic circle.</p>

-

-<h3>CURIOUS CAUSE OF CHANGE OF LEVEL.</h3>

-

-<p>Professor Hennessey, in 1857, <i>found the entire mass of rock

-and hill on which the Armagh Observatory is erected to be slightly,

-but to an astronomer quite perceptibly, tilted or canted, at one season

-to the east, at another to the west</i>. This he at first attributed to

-the varying power of the sun’s radiation to heat and expand

-the rock throughout the year; but he subsequently had reason

-to attribute it rather to the infiltration of water to the parts

-where the clay-slate and limestone rocks met, the varying

-quantity of the water exerting a powerful hydrostatic energy

-by which the position of the rock is slightly varied.</p>

-

-<p>Now Armagh and its observatory stand at the junction of

-the mountain limestone with the clay-slate, having, as it were,

-one leg on the former and the other on the latter; and both

-rocks probably reach downwards 1000 or 2000 feet. When

-rain falls, the one will absorb more water than the other; both

-will gain an increase of conductive power; but the one which

-has absorbed most water will have the greatest increase, and

-being thus the better conductor, will <i>draw a greater portion of

-heat from the hot nucleus below to the surface</i>&mdash;will become, in

-fact, temporarily hotter, and, as a consequence, <i>expand more

-than the other</i>. In a word, <i>both rocks will expand at the wet

-season; but the best conductor, or most absorbent rock, will expand

-most, and seem to tilt the hill to one side; at the dry season it will<span class="pagenum"><a name="Page_145" id="Page_145">145</a></span>

-subside most, and the hill will seem to be tilted in the opposite direction</i>.</p>

-

-<p>The fact is curious, and not less so are the results deducible

-from it. First, hills are higher at one season than another;

-a fact we might have supposed, but never could have ascertained

-by measurement. Secondly, they are highest, not, as we

-should have supposed, at the hottest season, but at the wettest.

-Thirdly, it is from the <i>different rates</i> of expansion of different

-rocks that this has been discovered. Fourthly, it is by converse

-with the <i>heavens</i> that it has been made known to us. A variation

-of probably half a second, or less, in the right ascension

-of three or four stars, observed at different seasons, no doubt

-revealed the fact to the sagacious astronomer of Armagh, and

-even enabled him to divine its cause.</p>

-

-<blockquote>

-

-<p>Professor Hennessey observes in connection with this phenomenon,

-that a very small change of ellipticity would suffice to lay bare or submerge

-extensive tracts of the globe. If, for example, the mean ellipticity

-of the ocean increased from 1/300 to 1/299, the level of the sea would

-be raised at the equator by about 228 feet, while under the parallel of

-52° it would be depressed by 196 feet. Shallow seas and banks in the

-latitudes of the British isles, and between them and the pole, would

-thus be converted into dry land, while low-lying plains and islands near

-the equator would be submerged. If similar phenomena occurred during

-early periods of geological history, they would manifestly influence the

-distribution of land and water during these periods; and with such a

-direction of the forces as that referred to, they would tend to increase

-the proportion of land in the polar and temperate regions of the earth,

-as compared with the equatorial regions during successive geological

-epochs. Such maps as those published by Sir Charles Lyell on the distribution

-of land and water in Europe during the Tertiary period, and

-those of M. Elie de Beaumont, contained in Beaudant’s <i>Geology</i>, would,

-if sufficiently extended, assist in verifying or disproving these views.</p></blockquote>

-

-<h3>THE OUTLINES OF CONTINENTS NOT FIXED.</h3>

-

-<p>Continents (says M. Agassiz) are only a patchwork formed

-by the emergence and subsidence of land. These processes are

-still going on in various parts of the globe. Where the shores

-of the continent are abrupt and high, the effect produced may

-be slight, as in Norway and Sweden, where a gradual elevation

-is going on without much alteration in their outlines. But if

-the continent of North America were to be depressed 1000 feet,

-nothing would remain of it except a few islands, and any elevation

-would add vast tracts to its shores.</p>

-

-<p>The west of Asia, comprising Palestine and the country

-about Ararat and the Caspian Sea, is below the level of the

-ocean, and a rent in the mountain-chains by which it is surrounded

-would transform it into a vast gulf.</p>

-

-<hr />

-

-<p><span class="pagenum"><a name="Page_146" id="Page_146">146</a></span></p>

-

-<div class="chapter"></div>

-<h2><a name="Meteorological" id="Meteorological"></a>Meteorological Phenomena.</h2>

-

-<h3>THE ATMOSPHERE.</h3>

-

-<p>A philosopher of the East, with a richness of imagery truly

-oriental, describes the Atmosphere as “a spherical shell which

-surrounds our planet to a depth which is unknown to us, by

-reason of its growing tenuity, as it is released from the pressure

-of its own superincumbent mass. Its upper surface cannot

-be nearer to us than 50, and can scarcely be more remote

-than 500, miles. It surrounds us on all sides, yet we see it not;

-it presses on us with a load of fifteen pounds on every square

-inch of surface of our bodies, or from seventy to one hundred

-tons on us in all, yet we do not so much as feel its weight.

-Softer than the softest down, more impalpable than the finest

-gossamer, it leaves the cobweb undisturbed, and scarcely stirs

-the lightest flower that feeds on the dew it supplies; yet it

-bears the fleets of nations on its wings around the world, and

-crushes the most refractory substances with its weight. When

-in motion, its force is sufficient to level the most stately forests

-and stable buildings with the earth&mdash;to raise the waters of the

-ocean into ridges like mountains, and dash the strongest ships

-to pieces like toys. It warms and cools by turns the earth and

-the living creatures that inhabit it. It draws up vapours from

-the sea and land, retains them dissolved in itself or suspended

-in cisterns of clouds, and throws them down again as rain or

-dew when they are required. It bends the rays of the sun

-from their path to give us the twilight of evening and of dawn;

-it disperses and refracts their various tints to beautify the approach

-and the retreat of the orb of day. But for the atmosphere

-sunshine would burst on us and fail us at once, and at once

-remove us from midnight darkness to the blaze of noon. We

-should have no twilight to soften and beautify the landscape;

-no clouds to shade us from the searching heat; but the bald

-earth, as it revolved on its axis, would turn its tanned and

-weakened front to the full and unmitigated rays of the lord of

-day. It affords the gas which vivifies and warms our frames,

-and receives into itself that which has been polluted by use

-and is thrown off as noxious. It feeds the flames of life exactly

-as it does that of the fire&mdash;it is in both cases consumed and

-affords the food of consumption&mdash;in both cases it becomes

-combined with charcoal, which requires it for combustion and

-is removed by it when this is over.”</p>

-

-<p><span class="pagenum"><a name="Page_147" id="Page_147">147</a></span></p>

-

-<h3>UNIVERSALITY OF THE ATMOSPHERE.</h3>

-

-<p>It is only the girdling, encircling air that flows above and

-around all that makes the whole world kin. The carbonic acid

-with which to-day our breathing fills the air, to-morrow makes

-its way round the world. The date-trees that grow round the

-falls of the Nile will drink it in by their leaves; the cedars of

-Lebanon will take of it to add to their stature; the cocoa-nuts

-of Tahiti will grow rapidly upon it; and the palms and bananas

-of Japan will change it into flowers. The oxygen we are

-breathing was distilled for us some short time ago by the magnolias

-of the Susquehanna; the great trees that skirt the Orinoco

-and the Amazon, the giant rhododendrons of the Himalayas,

-contributed to it, and the roses and myrtles of Cashmere,

-the cinnamon-tree of Ceylon, and the forest, older than the

-Flood, buried deep in the heart of Africa, far behind the Mountains

-of the Moon. The rain we see descending was thawed

-for us out of the icebergs which have watched the polar star

-for ages; and the lotus-lilies have soaked up from the Nile, and

-exhaled as vapour, snows that rested on the summits of the

-Alps.&mdash;<i>North-British Review.</i></p>

-

-<h3>THE HEIGHT OF THE ATMOSPHERE.</h3>

-

-<p>The differences existing between that which appertains to

-the air of heaven (the realms of universal space) and that which

-belongs to the strata of our terrestrial atmosphere are very

-striking. It is not possible, as well-attested facts prove, perfectly

-to explain the operations at work in the much-contested

-upper boundaries of our atmosphere. The extraordinary lightness

-of whole nights in the year 1831, during which small print

-might be read at midnight in the latitudes of Italy and the north

-of Germany, is a fact directly at variance with all we know

-according to the researches on the crepuscular theory and the

-height of the atmosphere. The phenomena of light depend

-upon conditions still less understood; and their variability at

-twilight, as well as in the zodiacal light, excite our astonishment.

-Yet the atmosphere which surrounds the earth is not

-thicker in proportion to the bulk of our globe than the line of

-a circle two inches in diameter when compared with the space

-which it encloses, or the down on the skin of a peach in comparison

-with the fruit inside.</p>

-

-<h3>COLOURS OF THE ATMOSPHERE.</h3>

-

-<p>Pure air is blue, because, according to Newton, the molecules

-of the air have the thickness necessary to reflect blue rays.

-When the sky is not perfectly pure, and the atmosphere is

-blended with perceptible vapours, the diffused light is mixed<span class="pagenum"><a name="Page_148" id="Page_148">148</a></span>

-with a large proportion of white. As the moon is yellow, the

-blue of the air assumes somewhat of a greenish tinge, or, in

-other words, becomes blended with yellow.&mdash;<i>Letter from Arago

-to Humboldt</i>; <i>Cosmos</i>, vol. iii.</p>

-

-<h3>BEAUTY OF TWILIGHT.</h3>

-

-<p>This phenomenon is caused by the refraction of solar light

-enabling it to diffuse itself gradually over our hemisphere, obscured

-by the shades of night, long before the sun appears, even

-when that luminary is eighteen degrees below our horizon. It

-is towards the poles that this reflected splendour of the great

-luminary is longest visible, often changing the whole of the

-night into a magic day, of which the inhabitants of southern

-Europe can form no adequate conception.</p>

-

-<h3>HOW PASCAL WEIGHED THE ATMOSPHERE.</h3>

-

-<p>Pascal’s treatise on the weight of the whole mass of air

-forms the basis of the modern science of Pneumatics. In order

-to prove that the mass of air presses by its weight on all the

-bodies which it surrounds, and also that it is elastic and compressible,

-he carried a balloon, half-filled with air, to the top

-of the Puy de Dome, a mountain about 500 toises above Clermont,

-in Auvergne. It gradually inflated itself as it ascended,

-and when it reached the summit it was quite full, and swollen

-as if fresh air had been blown into it; or, what is the same

-thing, it swelled in proportion as the weight of the column of

-air which pressed upon it was diminished. When again brought

-down it became more and more flaccid, and when it reached

-the bottom it resumed its original condition. In the nine

-chapters of which the treatise consists, Pascal shows that all

-the phenomena and effects hitherto ascribed to the horror of a

-vacuum arise from the weight of the mass of air; and after explaining

-the variable pressure of the atmosphere in different

-localities and in its different states, and the rise of water in

-pumps, he calculates that the whole mass of air round our globe

-weighs 8,983,889,440,000,000,000 French pounds.&mdash;<i>North-British

-Review</i>, No. 2.</p>

-

-<p>It seems probable, from many indications, that the greatest

-height at which visible clouds <i>ever exist</i> does not exceed ten

-miles; at which height the density of the air is about an eighth

-part of what it is at the level of the sea.&mdash;<i>Sir John Herschel.</i></p>

-

-<h3>VARIATIONS OF CLIMATE.</h3>

-

-<p>History informs us that many of the countries of Europe

-which now possess very mild winters, at one time experienced

-severe cold during this season of the year. The Tiber, at Rome,

-was often frozen over, and snow at one time lay for forty days<span class="pagenum"><a name="Page_149" id="Page_149">149</a></span>

-in that city. The Euxine Sea was frozen over every winter

-during the time of Ovid, and the rivers Rhine and Rhone used

-to be frozen over so deep that the ice sustained loaded wagons.

-The waters of the Tiber, Rhine, and Rhone, now flow freely

-every winter; ice is unknown in Rome, and the waves of the

-Euxine dash their wintry foam uncrystallised upon the rocks.

-Some have ascribed these climate changes to agriculture&mdash;the

-cutting down of dense forests, the exposing of the unturned soil

-to the summer’s sun, and the draining of great marshes. We

-do not believe that such great changes could be produced on

-the climate of any country by agriculture; and we are certain

-that no such theory can account for the contrary change of climate&mdash;from

-warm to cold winters&mdash;which history tells us has

-taken place in other countries than those named. Greenland

-received its name from the emerald herbage which once clothed

-its valleys and mountains; and its east coast, which is now inaccessible

-on account of perpetual ice heaped upon its shores,

-was in the eleventh century the seat of flourishing Scandinavian

-colonies, all trace of which is now lost. Cold Labrador was

-named Vinland by the Northmen, who visited it <span class="smcap smaller">A.D.</span> 1000, and

-were charmed with its then mild climate. The cause of these

-changes is an important inquiry.&mdash;<i>Scientific American.</i></p>

-

-<h3>AVERAGE CLIMATES.</h3>

-

-<p>When we consider the numerous and rapid changes which

-take place in our climate, it is a remarkable fact, that <i>the mean

-temperature of a place remains nearly the same</i>. The winter may

-be unusually cold, or the summer unusually hot, while the

-mean temperature has varied even less than a degree. A very

-warm summer is therefore likely to be accompanied with a

-cold winter; and in general, if we have any long period of

-cold weather, we may expect a similar period at a higher temperature.

-In general, however, in the same locality the relative

-distribution over summer and winter undergoes comparatively

-small variations; therefore every point of the globe has

-an average climate, though it is occasionally disturbed by different

-atmospheric changes.&mdash;<i>North-British Review</i>, No. 49.</p>

-

-<h3>THE FINEST CLIMATE IN THE WORLD.</h3>

-

-<p>Humboldt regards the climate of the Caspian Sea as the

-most salubrious in the world: here he found the most delicious

-fruits that he saw during his travels; and such was the purity

-of the air, that polished steel would not tarnish even by night

-exposure.</p>

-

-<p><span class="pagenum"><a name="Page_150" id="Page_150">150</a></span></p>

-

-<h3>THE PUREST ATMOSPHERES.</h3>

-

-<p>The cloudless purity and transparency of the atmosphere,

-which last for eight months at Santiago, in Chili, are so great,

-that Lieutenant Gilliss, with the first telescope ever constructed

-in America, having a diameter of seven inches, was clearly able

-to recognise the sixth star in the trapezium of Orion. If we

-are to rely upon the statements of the Rev. Mr. Stoddart, an

-American missionary, Oroomiah, in Persia, seems to be, in so

-far as regards the transparency of the atmosphere, the most

-suitable place in the world for an astronomical observatory.

-Writing to Sir John Herschel from that country, he mentions

-that he has been enabled to distinguish with the naked eye the

-satellites of Jupiter, the crescent of Venus, the rings of Saturn,

-and the constituent members of several double stars.</p>

-

-<h3>SEA-BREEZES AND LAND-BREEZES ILLUSTRATED.</h3>

-

-<p>When a fire is kindled on the hearth, we may, if we will

-observe the motes floating in the room, see that those nearest

-the chimney are the first to feel the draught and to obey it,&mdash;they

-are drawn into the blaze. The circle of inflowing air is

-gradually enlarged, until it is scarcely perceived in the remote

-parts of the room. Now the land is the hearth, the rays of the

-sun the fire, and the sea, with its cool and calm air, the room;

-and thus we have at our firesides the sea-breeze in miniature.</p>

-

-<p>When the sun goes down, the fire ceases; then the dry land

-commences to give off its surplus heat by radiation, so that by

-nine or ten o’clock it and the air above it are cooled below the

-sea temperature. The atmosphere on the land thus becomes

-heavier than that on the sea, and consequently there is a wind

-seaward, which we call the land-breeze.&mdash;<i>Maury.</i></p>

-

-<h3>SUPERIOR SALUBRITY OF THE WEST.</h3>

-

-<p>All large cities and towns have their best districts in the

-West;<a name="FNanchor_38" id="FNanchor_38" href="#Footnote_38" class="fnanchor">38</a> which choice the French <i>savans</i>, Pelouze, Pouillet,

-Boussingault, and Elie de Beaumont, attribute to the law of

-atmospheric pressure. “When,” say they, “the barometric

-column rises, smoke and pernicious emanations rapidly evaporate

-in space.” On the contrary, smoke and noxious vapours remain<span class="pagenum"><a name="Page_151" id="Page_151">151</a></span>

-in apartments, and on the surface of the soil. Now,

-of all winds, that which causes the greatest ascension of the

-barometric column is the east; and that which lowers it most

-is the west. When the latter blows, it carries with it to the

-eastern parts of the town all the deleterious gases from the

-west; and thus the inhabitants of the east have to support

-their own smoke and miasma, and those brought by western

-winds. When, on the contrary, the east wind blows, it purifies

-the air by causing to ascend the pernicious emanations which it

-cannot drive to the west. Consequently, the inhabitants of the

-west receive pure air, from whatever part of the horizon it may

-arrive; and as the west winds are most prevalent, they are the

-first to receive the air pure, and as it arrives from the country.</p>

-

-<h3>FERTILISATION OF CLOUDS.</h3>

-

-<p>As the navigator cruises in the Pacific Ocean among the

-islands of the trade-wind region, he sees gorgeous piles of cumuli,

-heaped up in fleecy masses, not only capping the island

-hills, but often overhanging the lowest islet of the tropics, and

-even standing above coral patches and hidden reefs; “a cloud

-by day.” to serve as a beacon to the lonely mariner out there at

-sea, and to warn him of shoals and dangers which no lead nor

-seaman’s eye has ever seen or sounded. These clouds, under

-favourable circumstances, may be seen gathering above the low

-coral island, preparing it for vegetation and fruitfulness in a

-very striking manner. As they are condensed into showers,

-one fancies that they are a sponge of the most exquisite and delicately

-elaborated material, and that he can see, as they “drop

-down their fatness,” the invisible but bountiful hand aloft that

-is pressing and squeezing it out.&mdash;<i>Maury.</i></p>

-

-<h3>BAROMETRIC MEASUREMENT.</h3>

-

-<p>We must not place too implicit a dependence on Barometrical

-Measurements. Ermann in Siberia, and Ross in the Antarctic

-Seas, have demonstrated the existence of localities on the

-earth’s surface where a permanent depression of the barometer

-prevails to the astonishing extent of nearly an inch.</p>

-

-<h3>GIGANTIC BAROMETER.</h3>

-

-<p>In the Great Exhibition Building of 1851 was a colossal

-Barometer, the tube and scale reaching from the floor of the

-gallery nearly to the top of the building, and the rise and fall

-of the indicating fluid being marked by feet instead of by tenths

-of inches. The column of mercury, supported by the pressure

-of the atmosphere, communicated with a perpendicular tube of<span class="pagenum"><a name="Page_152" id="Page_152">152</a></span>

-smaller bore, which contained a coloured fluid much lighter

-than mercury. When a diminution of atmospheric pressure occurred,

-the mercury in the large tube descended, and by its fall

-forced up the coloured fluid in the smaller tube; the fall of the

-one being indicated in a magnified ratio by the rise in the other.</p>

-

-<h3>THE ATMOSPHERE COMPARED TO A STEAM-ENGINE.</h3>

-

-<p>In this comparison, by Lieut. Maury, the South Seas themselves,

-in all their vast intertropical extent, are the boiler for

-the engine, and the northern hemisphere is its condenser. The

-mechanical power exerted by the air and the sun in lifting

-water from the earth, in transporting it from one place to another,

-and in letting it down again, is inconceivably great.

-The utilitarian who compares the water-power that the Falls

-of Niagara would afford if applied to machinery is astonished

-at the number of figures which are required to express its equivalent

-in horse-power. Yet what is the horse-power of the Niagara,

-falling a few steps, in comparison with the horse-power

-that is required to lift up as high as the clouds and let down

-again all the water that is discharged into the sea, not only by

-this river, but by all the other rivers in the world? The calculation

-has been made by engineers; and according to it, the

-force of making and lifting vapour from each area of one acre

-that is included on the surface of the earth, is equal to the

-power of thirty horses; and for the whole of the earth, it is 800

-times greater than all the water-power in Europe.</p>

-

-<h3>HOW DOES THE RAIN-MAKING VAPOUR GET FROM THE

-SOUTHERN INTO THE NORTHERN HEMISPHERE?</h3>

-

-<p>This comes with such regularity, that our rivers never go

-dry, and our springs fail not, because of the exact <i>compensation</i>

-of the grand machine of <i>the atmosphere</i>. It is exquisitely

-and wonderfully counterpoised. Late in the autumn of the

-north, throughout its winter, and in early spring, the sun is

-pouring his rays with the greatest intensity down upon the

-seas of the southern hemisphere; and this powerful engine,

-which we are contemplating, is pumping up the water there

-with the greatest activity; at the same time, the mean temperature

-of the entire southern hemisphere is about 10° higher

-than the northern. The heat which this heavy evaporation

-absorbs becomes latent, and with the moisture is carried

-through the upper regions of the atmosphere until it reaches

-our climates. Here the vapour is formed into clouds, condensed

-and precipitated; the heat which held their water in the

-state of vapour is set free, and becomes sensible heat; and it is

-that which contributes so much to temper our winter climate.<span class="pagenum"><a name="Page_153" id="Page_153">153</a></span>

-It clouds up in winter, turns warm, and we say we are going

-to have falling weather: that is because the process of condensation

-has already commenced, though no rain or snow may

-have fallen. Thus we feel this southern heat, that has been collected

-by the rays of the sun by the sea, been bottled away by

-the winds in the clouds of a southern summer, and set free in

-the process of condensation in our northern winter.</p>

-

-<p>Thus the South Seas should supply mainly the water for

-the engine just described, while the northern hemisphere condenses

-it; we should, therefore, have more rain in the northern

-hemisphere. The rivers tell us that we have, at least on

-the land; for the great water-courses of the globe, and half

-the fresh water in the world, are found on the north side of

-the equator. This fact is strongly corroborative of this hypothesis.

-To evaporate water enough annually from the ocean

-to cover the earth, on the average, five feet deep with rain; to

-transport it from one zone to another; and to precipitate it

-in the right places at suitable times and in the proportions

-due,&mdash;is one of the offices of the grand atmospherical machine.

-This water is evaporated principally from the torrid zone. Supposing

-it all to come thence, we shall have encircling the earth

-a belt of ocean 3000 miles in breadth, from which this atmosphere

-evaporates a layer of water annually sixteen feet in

-depth. And to hoist up as high as the clouds, and lower down

-again, all the water, in a lake sixteen feet deep and 3000 miles

-broad and 24,000 long, is the yearly business of this invisible

-machinery. What a powerful engine is the atmosphere! and

-how nicely adjusted must be all the cogs and wheels and springs

-and <i>compensations</i> of this exquisite piece of machinery, that it

-never wears out nor breaks down, nor fails to do its work at

-the right time and in the right way!&mdash;<i>Maury.</i></p>

-

-<h3>THE PHILOSOPHY OF RAIN.</h3>

-

-<p>To understand the philosophy of this beautiful and often

-sublime phenomenon, a few facts derived from observation and

-a long train of experiments must be remembered.</p>

-

-<blockquote>

-

-<p>1. Were the atmosphere every where at all times at a uniform temperature,

-we should never have rain, or hail, or snow. The water absorbed

-by it in evaporation from the sea and the earth’s surface would

-descend in an imperceptible vapour, or cease to be absorbed by the air

-when it was once fully saturated.</p>

-

-<p>2. The absorbing power of the atmosphere, and consequently its

-capability to retain humidity, is proportionally greater in warm than in

-cold air.</p>

-

-<p>3. The air near the surface of the earth is warmer than it is in the

-region of the clouds. The higher we ascend from the earth, the colder

-do we find the atmosphere. Hence the perpetual snow on very high

-mountains in the hottest climate.</p></blockquote>

-

-<p><span class="pagenum"><a name="Page_154" id="Page_154">154</a></span>

-Now when, from continued evaporation, the air is highly

-saturated with vapour, though it be invisible and the sky cloudless,

-if its temperature is suddenly reduced by cold currents descending

-from above or rushing from a higher to a lower latitude,

-its capacity to retain moisture is diminished, clouds are

-formed, and the result is rain. Air condenses as it cools, and,

-like a sponge filled with water and compressed, pours out the

-water which its diminished capacity cannot hold. What but

-Omniscience could have devised such an admirable arrangement

-for watering the earth?</p>

-

-<h3>INORDINATE RAINY CLIMATE.</h3>

-

-<p>The climate of the Khasia mountains, which lie north-east

-from Calcutta, and are separated by the valley of the Burrampooter

-River from the Himalaya range, is remarkable for the

-inordinate fall of rain&mdash;the greatest, it is said, which has ever

-been recorded. Mr. Yule, an English gentleman, established that

-in the single month of August 1841 there fell 264 inches of rain,

-or 22 feet, of which 12½ feet fell in the space of five consecutive

-days. This astonishing fact is confirmed by two other

-English travellers, who measured 30 inches of rain in twenty-four

-hours, and during seven months above 500 inches. This

-great rain-fall is attributed to the abruptness of the mountains

-which face the Bay of Bengal, and the intervening flat

-swamps 200 miles in extent. The district of the excessive rain

-is extremely limited; and but a few degrees farther west, rain

-is said to be almost unknown, and the winter falls of snow to

-seldom exceed two inches.</p>

-

-<h3>HOW DOES THE NORTH WIND DRIVE AWAY RAIN?</h3>

-

-<p>We may liken it to a wet sponge, and the decrease of temperature

-to the hand that squeezes that sponge. Finally, reaching

-the cold latitudes, all the moisture that a dew-point of

-zero, and even far below, can extract, is wrung from it; and

-this air then commences “to return according to his circuits”

-as dry atmosphere. And here we can quote Scripture again:

-“The north wind driveth away rain.” This is a meteorological

-fact of high authority and great importance in the study

-of the circulation of the atmosphere.&mdash;<i>Maury.</i></p>

-

-<h3>SIZE OF RAIN-DROPS.</h3>

-

-<p>The Drops of Rain vary in their size, perhaps from the 25th

-to the ¼ of an inch in diameter. In parting from the clouds,

-they precipitate their descent till the increasing resistance opposed

-by the air becomes equal to their weight, when they

-continue to fall with uniform velocity. This velocity is, therefore,<span class="pagenum"><a name="Page_155" id="Page_155">155</a></span>

-in a certain ratio to the diameter of the drops; hence

-thunder and other showers in which the drops are large pour

-down faster than a drizzling rain. A drop of the 25th part of

-an inch, in falling through the air, would, when it had arrived

-at its uniform velocity, only acquire a celerity of 11½ feet per

-second; while one of ¼ of an inch would equal a velocity of

-33½ feet.&mdash;<i>Leslie.</i></p>

-

-<h3>RAINLESS DISTRICTS.</h3>

-

-<p>In several parts of the world there is no rain at all. In the

-Old World there are two districts of this kind: the desert of

-Sahara in Africa, and in Asia part of Arabia, Syria, and Persia;

-the other district lies between north latitude 30° and 50°,

-and between 75° and 118° of east longitude, including Thibet,

-Gobiar Shama, and Mongolia. In the New World the rainless

-districts are of much less magnitude, occupying two narrow

-strips on the shores of Peru and Bolivia, and on the coast of

-Mexico and Guatemala, with a small district between Trinidad

-and Panama on the coast of Venezuela.</p>

-

-<h3>ALL THE RAIN IN THE WORLD.</h3>

-

-<p>The Pacific Ocean and the Indian Ocean may be considered

-as one sheet of water covering an area quite equal in extent to

-one half of that embraced by the whole surface of the earth;

-and the total annual fall of rain on the earth’s surface is 186,240

-cubic imperial miles. Not less than three-fourths of the vapour

-which makes this rain comes from this waste of waters; but,

-supposing that only half of this quantity, that is 93,120 cubic

-miles of rain, falls upon this sea, and that that much at least

-is taken up from it again as vapour, this would give 255 cubic

-miles as the quantity of water which is daily lifted up and

-poured back again into this expanse. It is taken up at one

-place, and rained down at another; and in this process, therefore,

-we have agencies for multitudes of partial and conflicting

-currents, all, in their set strength, apparently as uncertain as

-the winds.</p>

-

-<p>The better to appreciate the operation of such agencies in

-producing currents in the sea, imagine a district of 255 square

-miles to be set apart in the midst of the Pacific Ocean as the

-scene of operations for one day; then conceive a machine capable

-of pumping up in the twenty-four hours all the water to

-the depth of one mile in this district. The machine must not

-only pump up and bear off this immense quantity of water, but

-it must discharge it again into the sea on the same day, but

-at some other place.</p>

-

-<p>All the great rivers of America, Europe, and Asia are lifted<span class="pagenum"><a name="Page_156" id="Page_156">156</a></span>

-up by the atmosphere, and flow in invisible streams back

-through the air to their sources among the hills; and through

-channels so regular, certain, and well defined, that the quantity

-thus conveyed one year with the other is nearly the same:

-for that is the quantity which we see running down to the

-ocean through these rivers; and the quantity discharged annually

-by each river is, as far as we can judge, nearly a constant.&mdash;<i>Maury.</i></p>

-

-<h3>AN INCH OF RAIN ON THE ATLANTIC.</h3>

-

-<p>Lieutenant Maury thus computes the effect of a single Inch

-of Rain falling upon the Atlantic Ocean. The Atlantic includes

-an area of twenty-five millions of square miles. Suppose an

-inch of rain to fall upon only one-fifth of this vast expanse. It

-would weigh, says our author, three hundred and sixty thousand

-millions of tons: and the salt which, as water, it held in

-solution in the sea, and which, when that water was taken up

-as vapour, was left behind to disturb equilibrium, weighed sixteen

-millions more of tons, or nearly twice as much as all the

-ships in the world could carry at a cargo each. It might fall

-in an hour, or it might fall in a day; but, occupy what time it

-might in falling, this rain is calculated to exert so much force&mdash;which

-is inconceivably great&mdash;in disturbing the equilibrium

-of the ocean. If all the water discharged by the Mississippi

-river during the year were taken up in one mighty measure,

-and cast into the ocean at one effort, it would not make a

-greater disturbance in the equilibrium of the sea than would

-the fall of rain supposed. And yet so gentle are the operations

-of nature, that movements so vast are unperceived.</p>

-

-<h3>THE EQUATORIAL CLOUD-RING.</h3>

-

-<p>In crossing the Equatorial Doldrums, the voyager passes a

-ring of clouds that encircles the earth, and is stretched around

-our planet to regulate the quantity of precipitation in the rain-belt

-beneath it; to preserve the due quantum of heat on the

-face of the earth; to adjust the winds; and send out for distribution

-to the four corners vapours in proper quantities, to

-make up to each river-basin, climate, and season, its quota of

-sunshine, cloud, and moisture. Like the balance-wheel of a

-well-constructed chronometer, this cloud-ring affords the grand

-atmospherical machine the most exquisitely arranged <i>self-compensation</i>.

-Nature herself has hung a thermometer under this

-cloud-belt that is more perfect than any that man can construct,

-and its indications are not to be mistaken.&mdash;<i>Maury.</i></p>

-

-<h3>“THE EQUATORIAL DOLDRUMS”</h3>

-

-<p class="in0">is another of these calm places. Besides being a region of<span class="pagenum"><a name="Page_157" id="Page_157">157</a></span>

-calms and baffling winds, it is a region noted for its rains and

-clouds, which make it one of the most oppressive and disagreeable

-places at sea. The emigrant ships from Europe for Australia

-have to cross it. They are often baffled in it for two or

-three weeks; then the children and the passengers who are of

-delicate health suffer most. It is a frightful graveyard on the

-wayside to that golden land.</p>

-

-<h3>BEAUTY OF THE DEW-DROP.</h3>

-

-<p>The Dew-drop is familiar to every one from earliest infancy.

-Resting in luminous beads on the down of leaves, or pendent

-from the finest blades of grass, or threaded upon the floating

-lines of the gossamer, its “orient pearl” varies in size from

-the diameter of a small pea to the most minute atom that can

-be imagined to exist. Each of these, like the rain-drops, has

-the properties of reflecting and refracting light; hence, from so

-many minute prisms, the unfolded rays of the sun are sent up

-to the eye in colours of brilliancy similar to those of the rainbow.

-When the sunbeams traverse horizontally a very thickly-bedewed

-grass-plot, these colours arrange themselves so as to

-form an iris, or dew-bow; and if we select any one of these

-drops for observation, and steadily regard it while we gradually

-change our position, we shall find the prismatic colours follow

-each other in their regular order.&mdash;<i>Wells.</i></p>

-

-<h3>FALL OF DEW IN ONE YEAR.</h3>

-

-<p>The annual average quantity of Dew deposited in this country

-is estimated at a depth of about five inches, being about

-one-seventh of the mean quantity of moisture supposed to be

-received from the atmosphere all over Great Britain in the

-year; or about 22,161,337,355 tons, taking the ton at 252 imperial

-gallons.&mdash;<i>Wells.</i></p>

-

-<h3>GRADUATED SUPPLY OF DEW TO VEGETATION.</h3>

-

-<p>Each of the different grasses draws from the atmosphere

-during the night a supply of dew to recruit its energies dependent

-upon its form and peculiar radiating power. Every

-flower has a power of radiation of its own, subject to changes

-during the day and night, and the deposition of moisture on

-it is regulated by the peculiar law which this radiating power

-obeys; and this power will be influenced by the aspect which

-the flower presents to the sky, unfolding to the contemplative

-mind the most beautiful example of creative wisdom.<a name="FNanchor_39" id="FNanchor_39" href="#Footnote_39" class="fnanchor">39</a></p>

-

-<p><span class="pagenum"><a name="Page_158" id="Page_158">158</a></span></p>

-

-<h3>WARMTH OF SNOW IN ARCTIC LATITUDES.</h3>

-

-<p>The first warm Snows of August and September (says Dr.

-Kane), falling on a thickly-bleached carpet of grasses, heaths,

-and willows, enshrine the flowery growths which nestle round

-them in a non-conducting air chamber; and as each successive

-snow increases the thickness of the cover, we have, before the

-intense cold of winter sets in, a light cellular bed covered by

-drift, seven, eight, or ten feet deep, in which the plant retains

-its vitality. Dr. Kane has proved by experiments that the

-conducting power of the snow is proportioned to its compression

-by winds, rains, drifts, and congelation. The drifts that

-accumulate during nine months of the year are dispersed in

-well-defined layers of different density. We have first the

-warm cellular snows of fall, which surround the plant; next

-the finely-impacted snow-dust of winter; and above these the

-later humid deposits of spring. In the earlier summer, in the

-inclined slopes that face the sun, as the upper snow is melted

-and sinks upon the more compact layer below it is to a great

-extent arrested, and runs off like rain from a slope of clay. The

-plant reposes thus in its cellular bed, safe from the rush of

-waters, and protected from the nightly frosts by the icy roof

-above it.</p>

-

-<h3>IMPURITY OF SNOW.</h3>

-

-<p>It is believed that in ascending mountains difficult breathing

-is sooner felt upon snow than upon rock; and M. Boussingault,

-in his account of the ascent of Chimborazo, attributes

-this to the sensible deficiency of oxygen contained in the pores

-of the snow, which is exhaled when it melts. The fact that

-the air absorbed by snow is impure, was ascertained by De

-Saussure, and has been confirmed by Boussingault’s experiments.&mdash;<i>Quarterly

-Review</i>, No. 202.</p>

-

-<h3>SNOW PHENOMENON.</h3>

-

-<p>Professor Dove of Berlin relates, in illustration of the formation

-of clouds of Snow over plains situated at a distance

-from the cooling summits of mountains, that on one occasion a

-large company had gathered in a ballroom in Sweden. It was

-one of those icy starlight nights which in that country are

-so aptly called “iron nights.” The weather was clear and

-cold, and the ballroom was clear and warm; and the heat was

-so great, that several ladies fainted. An officer present tried

-to open a window; but it was frozen fast to the sill. As a last

-resort, he broke a pane of glass; the cold air rushed in, and it

-<i>snowed in the room</i>. A minute before all was clear; but the<span class="pagenum"><a name="Page_159" id="Page_159">159</a></span>

-warm air of the room had sustained an amount of moisture in

-a transparent condition which it was not able to maintain

-when mixed with the colder air from without. The vapour

-was first condensed, and then frozen.</p>

-

-<h3>ABSENCE OF SNOW IN SIBERIA.</h3>

-

-<p>There is in Siberia, M. Ermann informs us, an <i>entire district</i>

-in which during the winter the sky is constantly clear, and

-where a single particle of snow never falls.&mdash;<i>Arago.</i></p>

-

-<h3>ACCURACY OF THE CHINESE AS OBSERVERS.</h3>

-

-<p>The beautiful forms of snow-crystals have long since attracted

-Chinese observers; for from a remote period there has

-been met with in their conversation and books an axiomatic

-expression, to the effect that “snow-flakes are hexagonal,”

-showing the Chinese to be accurate observers of nature.</p>

-

-<h3>PROTECTION AGAINST HAIL AND STORMS.</h3>

-

-<p>Arago relates, that when, in 1847, two small agricultural

-districts of Bourgoyne had lost by Hail crops to the value of

-a million and a half of francs, certain of the proprietors went

-to consult him on the means of protecting them from like

-disasters. Resting on the hypothesis of the electric origin of

-hail, Arago suggested the discharge of the electricity of the

-clouds by means of balloons communicating by a metallic wire

-with the soil. This project was not carried out; but Arago

-persisted in believing in the effectiveness of the method proposed.</p>

-

-<blockquote>

-

-<p>Arago, in his <i>Meteorological Essays</i>, inquires whether the firing of

-cannon can dissipate storms. He cites several cases in its favour, and

-others which seem to oppose it; but he concludes by recommending it

-to his successors. Whilst Arago was propounding these questions, a

-person not conversant with science, the poet Méry, was collecting facts

-supporting the view, which he has published in his <i>Paris Futur</i>. His

-attention was attracted to the firing of cannon to dissipate storms in

-1828, whilst an assistant in the “Ecole de Tir” at Vincennes. Having

-observed that there was never any rain in the morning of the exercise

-of firing, he waited to examine military records, and found there, as he

-says, facts which justified the expressions of “Le soleil d’Austerlitz,”

-“Le soleil de juillet,” upon the morning of the Revolution of July; and

-he concluded by proposing to construct around Paris twelve towers of

-great height, which he calls “tours imbrifuges,” each carrying 100 cannons,

-which should be discharged into the air on the approach of a

-storm. About this time an incident occurred which in nowise confirmed

-the truth of M. Méry’s theory. The 14th of August was a fine day. On

-the 15th, the fête of the Empire, the sun shone out, the cannon thundered

-all day long, fireworks and illuminations were blazing from nine

-o’clock in the evening. Every thing conspired to verify the hypothesis

-of M. Méry, and chase away storms for a long time. But towards<span class="pagenum"><a name="Page_160" id="Page_160">160</a></span>

-eleven in the evening a torrent of rain burst upon Paris, in spite of the

-pretended influence of the discharge of cannon, and gave an occasion

-for the mobile Gallic mind to turn its attention in other directions.</p></blockquote>

-

-<h3>TERRIFIC HAILSTORM.</h3>

-

-<p>Jansen describes, from the log-book of the <i>Rhijin</i>, Captain

-Brandligt, in the South-Indian Ocean (25° south latitude)

-a Hurricane, accompanied by Hail, by which several of the

-crew were made blind, others had their faces cut open, and

-those who were in the rigging had their clothes torn off them.

-The master of the ship compared the sea “to a hilly landscape

-in winter covered with snow.” Does it not appear as if the

-“treasures of the hail” were opened, which were “reserved

-against the time of trouble, against the day of battle and

-war”?</p>

-

-<h3>HOW WATERSPOUTS ARE FORMED IN THE JAVA SEA.</h3>

-

-<p>Among the small groups of islands in this sea, in the day

-and night thunderstorms, the combat of the clouds appears to

-make them more thirsty than ever. In tunnel form, when they

-can no longer quench their thirst from the surrounding atmosphere,

-they descend near the surface of the sea, and appear to

-lap the water directly up with their black mouths. They are

-not always accompanied by strong winds; frequently more

-than one is seen at a time, whereupon the clouds whence they

-proceed disperse, and the ends of the Waterspouts bending

-over finally causes them to break in the middle. They seldom

-last longer than five minutes. As they are going away, the

-bulbous tube, which is as palpable as that of a thermometer,

-becomes broader at the base; and little clouds, like steam from

-the pipe of a locomotive, are continually thrown off from the

-circumference of the spout, and gradually the water is released,

-and the cloud whence the spout came again closes its

-mouth.</p>

-

-<h3>COLD IN HUDSON’S BAY.</h3>

-

-<p>Mr. R. M. Ballantyne, in his journal of six years’ residence

-in the territories of the Hudson’s Bay Company, tells us, that

-for part of October there is sometimes a little warm, or rather

-thawy, weather; but after that, until the following April, the

-thermometer seldom rises to the freezing point. In the depth

-of winter, the thermometer falls from 30° to 40°, 45°, and even

-49° <i>below zero</i> of Fahrenheit. This intense cold is not, however,

-so much felt as one might suppose; for during its continuance

-the air is perfectly calm. Were the slightest breath of wind

-to rise when the thermometer stands so low, no man could

-show his face to it for a moment. Forty degrees below zero,<span class="pagenum"><a name="Page_161" id="Page_161">161</a></span>

-and quite calm, is infinitely preferable to fifteen below, or

-thereabout, with a strong breeze of wind. Spirit of wine is,

-of course, the only thing that can be used in the thermometer;

-as mercury, were it exposed to such cold, would remain frozen

-nearly half the winter. Spirit never froze in any cold ever

-experienced at York Factory, unless when very much adulterated

-with water; and even then the spirit would remain liquid

-in the centre of the mass. Quicksilver easily freezes in this

-climate, and it has frequently been run into a bullet-mould,

-exposed to the cold air till frozen, and in this state rammed

-down a gun-barrel, and fired through a thick plank. The

-average cold may be set down at about 15° or 16° below zero,

-or 48° of frost. The houses at the Bay are built of wood, with

-double windows and doors. They are heated by large iron

-stoves, fed with wood; yet so intense is the cold, that when

-a stove has been in places red-hot, a basin of water in the room

-has been frozen solid.</p>

-

-<h3>PURITY OF WENHAM-LAKE ICE.</h3>

-

-<p>Professor Faraday attributes the purity of Wenham-Lake

-Ice to its being free from air-bubbles and from salts. The

-presence of the first makes it extremely difficult to succeed in

-making a lens of English ice which will concentrate the solar

-rays, and readily fire gunpowder; whereas nothing is easier

-than to perform this singular feat of igniting a combustible

-body by aid of a frozen mass if Wenham-Lake ice be employed.

-The absence of salts conduces greatly to the permanence of the

-ice; for where water is so frozen that the salts expelled are

-still contained in air-cavities and cracks, or form thin films

-between the layers of ice, these entangled salts cause the ice to

-melt at a lower temperature than 32°, and the liquefied portions

-give rise to streams and currents within the body of the

-ice which rapidly carry heat to the interior. The mass then

-goes on thawing within as well as without, and at temperatures

-below 32°; whereas pure, compact, Wenham-Lake ice

-can only thaw at 32°, and only on the outside of the mass.&mdash;<i>Sir

-Charles Lyell’s Second Visit to the United States.</i></p>

-

-<h3>ARCTIC TEMPERATURES.</h3>

-

-<p>Dr. Kane, in his Second Arctic Expedition, found the thermometers

-beginning to show unexampled temperature: they

-ranged from 60° to 70° below zero, and upon the taffrail of the

-brig 65°. The reduced mean of the best spirit-standards gave

-67° or 99° below the freezing point of water. At these temperatures

-chloric ether became solid, and chloroform exhibited

-a granular pellicle on its surface. Spirit of naphtha froze at 54°,

-and the oil of turpentine was solid at 63° and 65°.</p>

-

-<p><span class="pagenum"><a name="Page_162" id="Page_162">162</a></span></p>

-

-<h3>DR. RAE’S ARCTIC EXPLORATIONS.</h3>

-

-<p>The gold medal of the Royal Geographical Society was in

-1852 most rightfully awarded to this indefatigable Arctic explorer.

-His survey of the inlet of Boothia, in 1848, was unique

-in its kind. In Repulse Bay he maintained his party on deer,

-principally shot by himself; and spent ten months of an Arctic

-winter in a hut of stones, with no other fuel than a kind of hay

-of the <i>Andromeda tetragona</i>. Thus he preserved his men to

-execute surveying journeys of 1000 miles in the spring. Later

-he travelled 300 miles on snow-shoes. In a spring journey over

-the ice, with a pound of fat daily for fuel, accompanied by two

-men only, and trusting solely for shelter to snow-houses, which

-he taught his men to build, he accomplished 1060 miles in

-thirty-nine days, or twenty-seven miles per day, including stoppages,&mdash;a

-feat never equalled in Arctic travelling. In the

-spring journey, and that which followed in the summer in

-boats, 1700 miles were traversed in eighty days. Dr. Rae’s

-greatest sufferings, he once remarked to Sir George Back, arose

-from his being obliged to sleep upon his frozen mocassins in

-order to thaw them for the morning’s use.</p>

-

-<h3>PHENOMENA OF THE ARCTIC CLIMATE.</h3>

-

-<p>Sir John Richardson, in his history of his Expedition to

-these regions, describes the power of the sun in a cloudless sky

-to have been so great, that he was glad to take shelter in the

-water while the crews were engaged on the portages; and he

-has never felt the direct rays of the sun so oppressive as on

-some occasions in the high latitudes. Sir John observes:</p>

-

-<blockquote>

-

-<p>The rapid evaporation of both snow and ice in the winter and spring,

-long before the action of the sun has produced the slightest thaw or

-appearance of moisture, is evident by many facts of daily occurrence.

-Thus when a shirt, after being washed, is exposed in the open air to a

-temperature of from 40° to 50° below zero, it is instantly rigidly frozen,

-and may be broken if violently bent. If agitated when in this condition

-by a strong wind, it makes a rustling noise like theatrical thunder.</p>

-

-<p>In consequence of the extreme dryness of the atmosphere in winter,

-most articles of English manufacture brought to Rupert’s Land are

-shrivelled, bent, and broken. The handles of razors and knives, combs,

-ivory scales, &amp;c., kept in the warm room, are changed in this way. The

-human body also becomes vividly electric from the dryness of the skin.

-One cold night I rose from my bed, and was going out to observe the

-thermometer, with no other clothing than my flannel night-dress, when

-on my hand approaching the iron latch of the door, a distinct spark

-was elicited. Friction of the skin at almost all times in winter produced

-the electric odour.</p>

-

-<p>Even at midwinter we had but three hours and a half of daylight.

-On December 20th I required a candle to write at the window at ten in

-the morning. The sun was absent ten days, and its place in the heavens<span class="pagenum"><a name="Page_163" id="Page_163">163</a></span>

-at noon was denoted by rays of light shooting into the sky above the

-woods.</p>

-

-<p>The moon in the long nights was a most beautiful object, that satellite

-being constantly above the horizon for nearly a fortnight together.

-Venus also shone with a brilliancy which is never witnessed in a sky

-loaded with vapours; and, unless in snowy weather, our nights were

-always enlivened by the beams of the aurora.</p></blockquote>

-

-<h3>INTENSE HEAT AND COLD OF THE DESERT.</h3>

-

-<p>Among crystalline bodies, rock-crystal, or silica, is the best

-conductor of heat. This fact accounts for the steadiness of

-temperature in one set district, and the extremes of Heat and

-Cold presented by day and night on such sandy wastes as the

-Sahara. The sand, which is for the most part silica, drinks-in

-the noon-day heat, and loses it by night just as speedily.</p>

-

-<p>The influence of the hot winds from the Sahara has been

-observed in vessels traversing the Atlantic at a distance of upwards

-of 1100 geographical miles from the African shores, by

-the coating of impalpable dust upon the sails.</p>

-

-<h3>TRANSPORTING POWER OF WINDS.</h3>

-

-<p>The greatest example of their power is the <i>sand-flood</i> of

-Africa, which, moving gradually eastward, has overwhelmed

-all the land capable of tillage west of the Nile, unless sheltered

-by high mountains, and threatens ultimately to obliterate the

-rich plain of Egypt.</p>

-

-<h3>EXHILARATION IN ASCENDING MOUNTAINS.</h3>

-

-<p>At all elevations of from 6000 to 11,000 feet, and not unfrequently

-for even 2000 feet more, the pedestrian enjoys a pleasurable

-feeling, imparted by the consciousness of existence,

-similar to that which is described as so fascinating by those

-who have become familiar with the desert-life of the East. The

-body seems lighter, the nervous power greater, the appetite is

-increased; and fatigue, though felt for a time, is removed by

-the shortest repose. Some travellers have described the sensation

-by the impression that they do not actually press the

-ground, but that the blade of a knife could be inserted between

-the sole of the foot and the mountain top.&mdash;<i>Quarterly Review</i>,

-No. 202.</p>

-

-<h3>TO TELL THE APPROACH OF STORMS.</h3>

-

-<p>The proximity of Storms has been ascertained with accuracy

-by various indications of the electrical state of the atmosphere.

-Thus Professor Scott, of Sandhurst College, observed in Shetland

-that drinking-glasses, placed in an inverted position upon

-a shelf in a cupboard on the ground-floor of Belmont House,<span class="pagenum"><a name="Page_164" id="Page_164">164</a></span>

-occasionally emitted sounds as if they were tapped with a knife,

-or raised a little and then let fall on the shelf. These sounds

-preceded wind; and when they occurred, boats and vessels were

-immediately secured. The strength of the sound is said to be

-proportioned to the tempest that follows.</p>

-

-<h3>REVOLVING STORMS.</h3>

-

-<p>By the conjoint labours of Mr. Redfield, Colonel Reid, and

-Mr. Piddington, on the origin and nature of hurricanes, typhoons,

-or revolving storms, the following important results

-have been obtained. Their existence in moderate latitudes on

-both sides the equator; their absence in the immediate neighbourhood

-of the equatorial regions; and the fact, that while

-in the northern latitudes these storms revolve in a direction

-contrary to the hands of a watch the face of which is placed

-upwards, in the southern latitudes they rotate in the opposite

-direction,&mdash;are shown to be so many additions to the long chain

-of evidence by which the rotation of the earth as a physical

-fact is demonstrated.</p>

-

-<h3>IMPETUS OF A STORM.</h3>

-

-<p>Captain Sir S. Brown estimates, from experiments made by

-him at the extremity of the Brighton-Chain Pier in a heavy

-south-west gale, that the waves impinge on a cylindrical surface

-one foot high and one foot in diameter with a force equal

-to eighty pounds, to which must be added that of the wind,

-which in a violent storm exerts a pressure of forty pounds. He

-computed the collective impetus of the waves on the lower part

-of a lighthouse proposed to be built on the Wolf Rock (exposed

-to the most violent storms of the Atlantic), of the surf on the

-upper part, and of the wind on the whole, to be equal to 100

-tons.</p>

-

-<h3>HOW TO MAKE A STORM-GLASS.</h3>

-

-<p>This instrument consists of a glass tube, sealed at one end,

-and furnished with a brass cap at the other end, through which

-the air is admitted by a very small aperture. Nearly fill the

-tube with the following solution: camphor, 2½ drams; nitrate

-of potash, 38 grains; muriate of ammonia, 38 grains; water, 9

-drams; rectified spirit, 9 drams. Dissolve with heat. At the

-ordinary temperature of the atmosphere, plumose crystals are

-formed. On the approach of stormy weather, these crystals appear

-compressed into a compact mass at the bottom of the tube;

-while during fine weather they assume their plumose character,

-and extend a considerable way up the glass. These results depend

-upon the condition of the air, but they are not considered

-to afford any reliable indication of approaching weather.</p>

-

-<p><span class="pagenum"><a name="Page_165" id="Page_165">165</a></span></p>

-

-<h3>SPLENDOUR OF THE AURORA BOREALIS.</h3>

-

-<p>Humboldt thus beautifully describes this phenomenon:</p>

-

-<blockquote>

-

-<p>The intensity of this light is at times so great, that Lowenörn (on

-June 29, 1786) recognised its coruscation in bright sunshine. Motion

-renders the phenomenon more visible. Round the point in the vault of

-heaven which corresponds to the direction of the inclination of the

-needle the beams unite together to form the so-called corona, the

-crown of the Northern Light, which encircles the summit of the heavenly

-canopy with a milder radiance and unflickering emanations of light.

-It is only in rare instances that a perfect crown or circle is formed; but

-on its completion, the phenomenon has invariably reached its maximum,

-and the radiations become less frequent, shorter, and more colourless.

-The crown, and the luminous arches break up; and the whole vault of

-heaven becomes covered with irregularly scattered, broad, faint, almost

-ashy-gray, luminous, immovable patches, which in their turn disappear,

-leaving nothing but a trace of a dark smoke-like segment on the

-horizon. There often remains nothing of the whole spectacle but a white

-delicate cloud with feathery edges, or divided at equal distances into

-small roundish groups like cirro-cumuli.&mdash;<i>Cosmos</i>, vol. i.</p></blockquote>

-

-<p>Among many theories of this phenomenon is that of Lieutenant

-Hooper, R.N., who has stated to the British Association

-that he believes “the Aurora Borealis to be no more nor less

-than the moisture in some shape (whether dew or vapour, liquid

-or frozen), illuminated by the heavenly bodies, either directly, or

-reflecting their rays from the frozen masses around the Pole,

-or even from the immediately proximate snow-clad earth.”</p>

-

-<h3>VARIETIES OF LIGHTNING.</h3>

-

-<p>According to Arago’s investigations, the evolution of Lightning

-is of three kinds: zigzag, and sharply defined at the

-edges; in sheets of light, illuminating a whole cloud, which

-seems to open and reveal the light within it; and in the form

-of fire-balls. The duration of the first two kinds scarcely continues

-the thousandth part of a second; but the globular lightning

-moves much more slowly, remaining visible for several

-seconds.</p>

-

-<h3>WHAT IS SHEET-LIGHTNING?</h3>

-

-<p>This electric phenomenon is unaccompanied by thunder, or

-too distant to be heard: when it appears, the whole sky, but

-particularly the horizon, is suddenly illuminated with a flickering

-flash. Philosophers differ much as to its cause. Matteucci

-supposes it to be produced either during evaporation, or

-evolved (according to Pouillet’s theory) in the process of vegetation;

-or generated by chemical action in the great laboratory

-of nature, the earth, and accumulated in the lower strata of the

-air in consequence of the ground being an imperfect conductor.</p>

-

-<p><span class="pagenum"><a name="Page_166" id="Page_166">166</a></span></p><blockquote>

-

-<p>Arago and Kamtz, however, consider sheet-lightning as <i>reflections

-of distant thunderstorms</i>. Saussure observed sheet-lightning in the direction

-of Geneva, from the Hospice du Grimsel, on the 10th and 11th

-of July 1783; while at the same time a terrific thunderstorm raged at

-Geneva. Howard, from Tottenham, near London, on July 31, 1813,

-saw sheet-lightning towards the south-east, while the sky was bespangled

-with stars, not a cloud floating in the air; at the same time a thunderstorm

-raged at Hastings, and in France from Calais to Dunkirk.

-Arago supports his opinion, that the phenomenon is <i>reflected lightning</i>,

-by the following illustration: In 1803, when observations were being

-made for determining the longitude, M. de Zach, on the Brocken, used

-a few ounces of gunpowder as a signal, the flash of which was visible

-from the Klenlenberg, sixty leagues off, although these mountains are

-invisible from each other.</p></blockquote>

-

-<h3>PRODUCTION OF LIGHTNING BY RAIN.</h3>

-

-<p>A sudden gust of rain is almost sure to succeed a violent

-detonation immediately overhead. Mr. Birt, the meteorologist,

-asks: Is this rain a <i>cause</i> or <i>consequence</i> of the electric discharge?

-To this he replies:</p>

-

-<blockquote>

-

-<p>In the sudden agglomeration of many minute and feebly electrified

-globules into one rain-drop, the quantity of electricity is increased in a

-greater proportion than the surface over which (according to the laws of

-electric distribution) it is spread. By tension, therefore, it is increased,

-and may attain the point when it is capable of separating from the <i>drop</i>

-to seek the surface of the <i>cloud</i>, or of the newly-formed descending body

-of rain, which, under such circumstances, may be regarded as a conducting

-medium. Arrived at this surface, the tension, for the same reason,

-becomes enormous, and a flash escapes. This theory Mr. Birt has confirmed

-by observation of rain in thunderstorms.</p></blockquote>

-

-<h3>SERVICE OF LIGHTNING-CONDUCTORS.</h3>

-

-<p>Sir David Brewster relates a remarkable instance of a tree

-in Clandeboye Park, in a thick mass of wood, and <i>not the tallest

-of the group</i>, being struck by lightning, which passed down the

-trunk into the ground, rending the tree asunder. This shows

-that an object may be struck by lightning in a locality where

-there are numerous conducting points more elevated than

-itself; and at the same time proves that lightning cannot be

-diverted from its course by lofty isolated conductors, but that

-the protection of buildings from this species of meteor can only

-be effected by conductors stretching out in all directions.</p>

-

-<p>Professor Silliman states, that lightning-rods cannot be relied

-upon unless they reach the earth where it is permanently

-wet; and that the best security is afforded by carrying the rod,

-or some good metallic conductor duly connected with it, to the

-water in the well, or to some other water that never fails. The

-professor’s house, it seems, was struck; but his lightning-rods

-were not more than two or three inches in the ground, and were

-therefore virtually of no avail in protecting the building.</p>

-

-<p><span class="pagenum"><a name="Page_167" id="Page_167">167</a></span></p>

-

-<h3>ANCIENT LIGHTNING-CONDUCTOR.</h3>

-

-<p>Humboldt informs us, that “the most important ancient

-notice of the relations between lightning and conducting metals

-is that of Ctesias, in his <i>Indica</i>, cap. iv. p. 190. He possessed

-two iron swords, presents from the king Artaxerxes Mnemon

-and from his mother Parasytis, which, when planted in the

-earth, averted clouds, hail, and <i>strokes of lightning</i>. He had

-himself seen the operation, for the king had twice made the

-experiment before his eyes.”&mdash;<i>Cosmos</i>, vol. ii.</p>

-

-<h3>THE TEMPLE OF JERUSALEM PROTECTED FROM LIGHTNING.</h3>

-

-<p>We do not learn, either from the Bible or Josephus, that

-the Temple at Jerusalem was ever struck by Lightning during

-an interval of more than a thousand years, from the time of

-Solomon to the year 70; although, from its situation, it was

-completely exposed to the violent thunderstorms of Palestine.</p>

-

-<p>By a fortuitous circumstance, the Temple was crowned with

-lightning-conductors similar to those which we now employ,

-and which we owe to Franklin’s discovery. The roof, constructed

-in what we call the Italian manner, and covered with

-boards of cedar, having a thick coating of gold, was garnished

-from end to end with long pointed and gilt iron or steel lances,

-which, Josephus says, were intended to prevent birds from roosting

-on the roof and soiling it. The walls were overlaid throughout

-with wood, thickly gilt. Lastly, there were in the courts

-of the Temple cisterns, into which the rain from the roof was

-conducted by <i>metallic pipes</i>. We have here both the lightning-rods

-and a means of conduction so abundant, that Lichtenberg

-is quite right in saying that many of the present apparatuses

-are far from offering in their construction so satisfactory a

-combination of circumstances.&mdash;<i>Abridged from Arago’s Meteorological

-Essays.</i></p>

-

-<h3>HOW ST. PAUL’S CATHEDRAL IS PROTECTED FROM LIGHTNING.</h3>

-

-<p>In March 1769, the Dean and Chapter of St. Paul’s addressed

-a letter to the Royal Society, requesting their opinion

-as to the best and most effectual method of fixing electrical

-conductors on the cathedral. A committee was formed for the

-purpose, and Benjamin Franklin was one of the members; their

-report was made, and the conductors were fixed as follows:</p>

-

-<blockquote>

-

-<p>The seven iron scrolls supporting the ball and cross are connected

-with other rods (used merely as conductors), which unite them with

-several large bars, descending obliquely to the stone-work of the lantern,

-and connected by an iron ring with four other iron bars to the lead

-covering of the great cupola, a distance of forty-eight feet; thence the<span class="pagenum"><a name="Page_168" id="Page_168">168</a></span>

-communication is continued by the rain-water pipes to the lead-covered

-roof, and thence by lead water-pipes which pass into the earth; thus

-completing the entire communication from the cross to the ground,

-partly through iron, and partly through lead. On the clock-tower a

-bar of iron connects the pine-apple at the top with the iron staircase,

-and thence with the lead on the roof of the church. The bell-tower is

-similarly protected. By these means the metal used in the building is

-made available as conductors; the metal employed merely for that purpose

-being exceedingly small in quantity.&mdash;<i>Curiosities of London.</i></p></blockquote>

-

-<h3>VARIOUS EFFECTS OF LIGHTNING.</h3>

-

-<p>Dr. Hibbert tells us that upon the western coast of Scotland

-and Ireland, Lightning coöperates with the violence of

-the storm in shattering solid rocks, and heaping them in piles

-of enormous fragments, both on dry land and beneath the

-water.</p>

-

-<p>Euler informs us, in his <i>Letters to a German Princess</i>, that

-he corresponded with a Moravian priest named Divisch, who

-assured him that he had averted during a whole summer every

-thunderstorm which threatened his own habitation and the

-neighbourhood, by means of a machine constructed upon the

-principles of electricity; that the machinery sensibly attracted

-the clouds, and constrained them to descend quietly in a distillation,

-without any but a very distant thunderclap. Euler

-assures us that “the fact is undoubted, and confirmed by irresistible

-proof.”</p>

-

-<p>About the year 1811, in the village of Phillipsthal, in Eastern

-Prussia, an attempt was made to split an immense stone

-into a multitude of pieces by means of lightning. A bar of

-iron, in the form of a conductor, was previously fixed to the

-stone; and the experiment was attended with complete success;

-for during the very first thunderstorm the lightning burst the

-stone without displacing it.</p>

-

-<p>The celebrated Duhamel du Monceau says, that lightning,

-unaccompanied by thunder, wind, or rain, has the property of

-breaking oat-stalks. The farmers are acquainted with this

-effect, and say that the lightning breaks down the oats. This

-is a well-received opinion with the farmers in Devonshire.</p>

-

-<p>Lightning has in some cases the property of reducing solid

-bodies to ashes, or to pulverisation,&mdash;even the human body,&mdash;without

-there being any signs of heat. The effects of lightning

-on paralysis are very remarkable, in some cases curing, in others

-causing, that disease.</p>

-

-<p>The returning stroke of lightning is well known to be due

-to the restoration of the natural electric state, after it has been

-disturbed by induction.</p>

-

-<p><span class="pagenum"><a name="Page_169" id="Page_169">169</a></span></p>

-

-<h3>A THUNDERSTORM SEEN FROM A BALLOON.</h3>

-

-<p>Mr. John West, the American aeronaut, in his observations

-made during his numerous ascents, describes a storm viewed

-from above the clouds to have the appearance of ebullition.

-The bulging upper surface of the cloud resembles a vast sea of

-boiling and upheaving snow; the noise of the falling rain is

-like that of a waterfall over a precipice; the thunder above

-the cloud is not loud, and the flashes of lightning appear like

-streaks of intensely white fire on a surface of white vapour.

-He thus describes a side view of a storm which he witnessed

-June 3, 1852, in his balloon excursion from Portsmouth, Ohio:</p>

-

-<blockquote>

-

-<p>Although the sun was shining on me, the rain and small hail were

-rattling on the balloon. A rainbow, or prismatically-coloured arch or

-horse-shoe, was reflected against the sun; and as the point of observation

-changed laterally and perpendicularly, the perspective of this golden

-grotto changed its hues and forms. Above and behind this arch was

-going on the most terrific thunder; but no zigzag lightning was perceptible,

-only bright flashes, like explosions of “Roman candles” in

-fireworks. Occasionally there was a zigzag explosion in the cloud immediately

-below, the thunder sounding like a <i>feu-de-joie</i> of a rifle-corps.

-Then an orange-coloured wave of light seemed to fall from the upper to

-the lower cloud; this was “still-lightning.” Meanwhile intense electrical

-action was going on <i>in the balloon</i>, such as expansion, tremulous

-tension, lifting papers ten feet out of the car below the balloon and

-then dropping them, &amp;c. The close view of this Ohio storm was truly

-sublime; its rushing noise almost appalling.</p></blockquote>

-

-<p>Ascending from the earth with a balloon, in the rear of a

-storm, and mounted up a thousand feet above it, the balloon

-will soon override the storm, and may descend in advance of

-it. Mr. West has experienced this several times.</p>

-

-<h3>REMARKABLE AERONAUTIC VOYAGE.</h3>

-

-<p>Mr. Sadler, the celebrated aeronaut, ascended on one occasion

-in a balloon from Dublin, and was wafted across the Irish

-Channel; when, on his approach to the Welsh coast, the balloon

-descended nearly to the surface of the sea. By this time the

-sun was set, and the shades of evening began to close in. He

-threw out nearly all his ballast, and suddenly sprang upward

-to a great height; and by so doing brought his horizon to <i>dip</i>

-below the sun, producing the whole phenomenon of a western

-sunrise. Subsequently descending in Wales, he of course

-witnessed a second sunset on the same evening.&mdash;<i>Sir John

-Herschel’s Outlines of Astronomy.</i></p>

-

-<hr />

-

-<p><span class="pagenum"><a name="Page_170" id="Page_170">170</a></span></p>

-

-<div class="chapter"></div>

-<h2 title="Physical Geography of the Sea."><a name="Geography" id="Geography"></a>Physical Geography of the Sea.<a name="FNanchor_40" id="FNanchor_40" href="#Footnote_40" class="fnanchor smaller">40</a></h2>

-

-<h3>CLIMATES OF THE SEA.</h3>

-

-<p>The fauna and flora of the Sea are as much the creatures

-of Climate, and are as dependent for their well-being upon

-temperature, as are the fauna and flora of the dry land. Were

-it not so, we should find the fish and the algæ, the marine

-insect and the coral, distributed equally and alike in all parts

-of the ocean; the polar whale would delight in the torrid

-zone; and the habitat of the pearl oyster would be also under

-the iceberg, or in frigid waters colder than the melting ice.</p>

-

-<h3>THE CIRCULATION OF THE SEA.</h3>

-

-<p>The coral islands, reefs, and beds with which the Pacific

-Ocean is studded and garnished, were built up of materials

-which a certain kind of insect quarried from the sea-water.

-The currents of the sea ministered to this little insect; they

-were its <i>hod-carriers</i>. When fresh supplies of solid matter

-were wanted for the coral rock upon which the foundations of

-the Polynesian Islands were laid, these hod-carriers brought

-them in unfailing streams of sea-water, loaded with food and

-building-materials for the coralline: the obedient currents

-thread the widest and the deepest sea. Now we know that

-its adaptations are suited to all the wants of every one of its

-inhabitants,&mdash;to the wants of the coral insect as well as those

-of the whale. Hence <i>we know</i> that the sea has its system of

-circulation: for it transports materials for the coral rock from

-one part of the world to another; its currents receive them

-from rivers, and hand them over to the little mason for the

-structure of the most stupendous works of solid masonry that

-man has ever seen&mdash;the coral islands of the sea.</p>

-

-<h3>TEMPERATURE OF THE SEA.</h3>

-

-<p>Between the hottest hour of the day and the coldest hour

-of the night there is frequently a change of four degrees in

-the Temperature of the Sea. Taking one-fifth of the Atlantic

-Ocean for the scene of operation, and the difference of four<span class="pagenum"><a name="Page_171" id="Page_171">171</a></span>

-degrees to extend only ten feet below the surface, the total and

-absolute change made in such a mass of sea-water, by altering

-its temperature two degrees, is equivalent to a change in its

-volume of 390,000,000 cubic feet.</p>

-

-<h3>TRANSPARENCY OF THE OCEAN.</h3>

-

-<p>Captain Glynn, U.S.N., has made some interesting observations,

-ranging over 200° of latitude, in different oceans, in

-very high latitudes, and near the equator. His apparatus was

-simple: a common white dinner-plate, slung so as to lie in

-the water horizontally, and sunk by an iron pot with a line.

-Numbering the fathoms at which the plate was visible below

-the surface, Captain Glynn saw it on two occasions, at the

-maximum, twenty-five fathoms (150 feet) deep; the water was

-extraordinarily clear, and to lie in the boat and look down was

-like looking down from the mast-head; and the objects were

-clearly defined to a great depth.</p>

-

-<h3>THE BASIN OF THE ATLANTIC.</h3>

-

-<p>In its entire length, the basin of this sea is a long trough,

-separating the Old World from the New, and extending probably

-from pole to pole.</p>

-

-<p>This ocean-furrow was scored into the solid crust of our

-planet by the Almighty hand, that there the waters which

-“he called seas” might be gathered together so as to “let the

-dry land appear,” and fit the earth for the habitation of man.</p>

-

-<p>From the top of Chimborazo to the bottom of the Atlantic,

-at the deepest place yet recognised by the plummet in the

-North Atlantic, the distance in a vertical line is nine miles.</p>

-

-<p>Could the waters of the Atlantic be drawn off, so as to

-expose to view this great sea-gash, which separates continents,

-and extends from the Arctic to the Antarctic, it would present

-a scene the most grand, rugged, and imposing. The very ribs

-of the solid earth, with the foundations of the sea, would be

-brought to light; and we should have presented to us at one

-view, in the empty cradle of the ocean, “a thousand fearful

-wrecks,” with that dreadful array of dead men’s skulls, great

-anchors, heaps of pearls and inestimable stones, which, in the

-dreamer’s eye, lie scattered on the bottom of the sea, making

-it hideous with sights of ugly death.</p>

-

-<h3>GALES OF THE ATLANTIC.</h3>

-

-<p>Lieutenant Maury has, in a series of charts of the North

-and South Atlantic, exhibited, by means of colours, the prevalence

-of Gales over the more stormy parts of the oceans for

-each month in the year. One colour shows the region in which<span class="pagenum"><a name="Page_172" id="Page_172">172</a></span>

-there is a gale every six days; another colour every six to ten

-days; another every ten to fourteen days: and there is a separate

-chart for each month and each ocean.</p>

-

-<h3>SOLITUDE AT SEA.</h3>

-

-<p>Between Humboldt’s Current of Peru and the great equatorial

-flow, there is “a desolate region,” rarely visited by the

-whale, either sperm or right. Formerly this part of the ocean

-was seldom whitened by the sails of a ship, or enlivened by the

-presence of man. Neither the industrial pursuits of the sea

-nor the highways of commerce called him into it. Now and

-then a roving cruiser or an enterprising whalesman passed that

-way; but to all else it was an unfrequented part of the ocean,

-and so remained until the gold-fields of Australia and the

-guano islands of Peru made it a thoroughfare. All vessels

-bound from Australia to South America now pass through it;

-and in the journals of some of them it is described as a region

-almost void of the signs of life in both sea and air. In the

-South-Pacific Ocean especially, where there is such a wide expanse

-of water, sea-birds often exhibit a companionship with

-a vessel, and will follow and keep company with it through

-storm and calm for weeks together. Even the albatross and

-Cape pigeon, that delight in the stormy regions of Cape Horn

-and the inhospitable climates of the Antarctic regions, not unfrequently

-accompany vessels into the perpetual summer of the

-tropics. The sea-birds that join the ship as she clears Australia

-will, it is said, follow her to this region, and then disappear.

-Even the chirp of the stormy petrel ceases to be heard

-here, and the sea itself is said to be singularly barren of “moving

-creatures that have life.”</p>

-

-<h3>BOTTLES AND CURRENTS AT SEA.</h3>

-

-<p>Seafaring people often throw a bottle overboard, with a

-paper stating the time and place at which it is done. In the

-absence of other information as to Currents, that afforded by

-these mute little navigators is of great value. They leave no

-track behind them, it is true, and their routes cannot be ascertained;

-but knowing where they are cast, and seeing where

-they are found, some idea may be formed as to their course.

-Straight lines may at least be drawn, showing the shortest distance

-from the beginning to the end of their voyage, with the

-time elapsed. Admiral Beechey has prepared a chart, representing,

-in this way, the tracks of more than 100 bottles.

-From this it appears that the waters from every quarter of the

-Atlantic tend towards the Gulf of Mexico and its stream. Bottles

-cast into the sea midway between the Old and the New<span class="pagenum"><a name="Page_173" id="Page_173">173</a></span>

-Worlds, near the coasts of Europe, Africa, and America at the

-extreme north or farthest south, have been found either in the

-West Indies, or the British Isles, or within the well-known

-range of Gulf-Stream waters.</p>

-

-<h3>“THE HORSE LATITUDES”</h3>

-

-<p class="in0">are the belts of calms and light airs which border the polar

-edge of the north-east trade-winds. They are so called from

-the circumstance that vessels formerly bound from New England

-to the West Indies, with a deck-load of horses, were often

-so delayed in this calm belt of Cancer, that, from the want of

-water for their animals, they were compelled to throw a portion

-of them overboard.</p>

-

-<h3>“WHITE WATER” AND LUMINOUS ANIMALS AT SEA.</h3>

-

-<p>Captain Kingman, of the American clipper-ship <i>Shooting

-Star</i>, in lat. 8° 46′ S., long. 105° 30′ E., describes a patch of

-<i>white water</i>, about twenty-three miles in length, making the

-whole ocean appear like a plain covered with snow. He filled

-a 60-gallon tub with the water, and found it to contain small

-luminous particles seeming to be alive with worms and insects,

-resembling a grand display of rockets and serpents seen

-at a great distance in a dark night; some of the serpents appearing

-to be six inches in length, and very luminous. On

-being taken up, they emitted light until brought within a few

-feet of a lamp, when nothing was visible; but by aid of a sextant’s

-magnifier they could be plainly seen&mdash;a jelly-like substance,

-without colour. A specimen two inches long was visible

-to the naked eye; it was about the size of a large hair, and

-tapered at the ends. By bringing one end within about one-fourth

-of an inch of a lighted lamp, the flame was attracted

-towards it, and burned with a red light; the substance crisped

-in burning, something like hair, or appeared of a red heat

-before being consumed. In a glass of the water there were

-several small round substances (say 1/16th of an inch in diameter)

-which had the power of expanding and contracting; when expanded,

-the outer rim appeared like a circular saw, the teeth

-turned inward.</p>

-

-<p>The scene from the clipper’s deck was one of awful grandeur:

-the sea having turned to phosphorus, and the heavens

-being hung in blackness, and the stars going out, seemed to

-indicate that all nature was preparing for that last grand conflagration

-which we are taught to believe will annihilate this

-material world.</p>

-

-<h3>INVENTION OF THE LOG.</h3>

-

-<p>Long before the introduction of the Log, hour-glasses were<span class="pagenum"><a name="Page_174" id="Page_174">174</a></span>

-used to tell the distance in sailing. Columbus, Juan de la

-Cosa, Sebastian Cabot, and Vasco de Gama, were not acquainted

-with the Log and its mode of application; and they estimated

-the ship’s speed merely by the eye, while they found the distance

-they had made by the running-down of the sand in the

-<i>ampotellas</i>, or hour-glasses. The Log for the measurement of

-the distance traversed is stated by writers on navigation not to

-have been invented until the end of the sixteenth or the beginning

-of the seventeenth century (see <i>Encyclopædia Britannica</i>,

-7th edition, 1842). The precise date is not known; but it is

-certain that Pigafetta, the companion of Magellan, speaks, in

-1521, of the Log as a well-known means of finding the course

-passed over. Navarete places the use of the log-line in English

-ships in 1577.</p>

-

-<h3>LIFE OF THE SEA-DEEPS.</h3>

-

-<p>The ocean teems with life, we know. Of the four elements

-of the old philosophers,&mdash;fire, earth, air, and water,&mdash;perhaps

-the sea most of all abounds with living creatures. The space

-occupied on the surface of our planet by the different families

-of animals and their remains is inversely as the size of the individual;

-the smaller the animal, generally speaking, the greater

-the space occupied by his remains. Take the elephant and his

-remains, and a microscopic animal and his, and compare them;

-the contrast as to space occupied is as striking as that of the

-coral reef or island with the dimensions of the whale. The

-graveyard that would hold the corallines, is larger than the

-graveyard that would hold the elephants.</p>

-

-<h3>DEPTHS OF OCEAN AND AIR UNKNOWN.</h3>

-

-<p>At some few places under the tropics, no bottom has been

-found with soundings of 26,000 feet, or more than four miles;

-whilst in the air, if, according to Wollaston, we may assume

-that it has a limit from which waves of sound may be reverberated,

-the phenomenon of twilight would incline us to assume

-a height at least nine times as great. The aerial ocean rests

-partly on the solid earth, whose mountain-chains and elevated

-plateaus rise like green wooded shoals, and partly on the sea,

-whose surface forms a moving base, on which rest the lower,

-denser, and more saturated strata of air.&mdash;<i>Humboldt’s Cosmos</i>,

-vol. i.</p>

-

-<p>The old Alexandrian mathematicians, on the testimony of

-Plutarch, believed the depth of the sea to depend on the height

-of the mountains. Mr. W. Darling has propounded to the

-British Association the theory, that as the sea covers three

-times the area of the land, so it is reasonable to suppose that

-the depth of the ocean, and that for a large portion, is three<span class="pagenum"><a name="Page_175" id="Page_175">175</a></span>

-times as great as the height of the highest mountain. Recent

-soundings show depths in the sea much greater than any elevations

-on the surface of the earth; for a line has been veered

-to the extent of seven miles.&mdash;<i>Dr. Scoresby.</i></p>

-

-<h3>GREATEST ASCERTAINED DEPTH OF THE SEA.</h3>

-

-<p>In the dynamical theory of the tides, the ratio of the effects

-of the sun and moon depends, not only on the masses, distances,

-and periodic times of the two luminaries, but also on

-the Depth of the Sea; and this, accordingly, may be computed

-when the other quantities are known. In this manner Professor

-Haughton has deduced, from the solar and lunar coefficients

-of the diurnal tide, a mean depth of 5·12 miles; a

-result which accords in a remarkable manner with that inferred

-from the ratio of the semi-diurnal co-efficients as obtained by

-Laplace from the Brest observations. Professor Hennessey

-states, that from what is now known regarding the depth of the

-ocean, the continents would appear as plateaus elevated above

-the oceanic depressions to an amount which, although small

-compared to the earth’s radius, would be considerable when

-compared to its outswelling at the equator and its flattening

-towards the poles; and the surface thus presented would be

-the true surface of the earth.</p>

-

-<p>The greatest depths at which the bottom of the sea has been

-reached with the plummet are in the North-Atlantic Ocean;

-and the places where it has been fathomed (by the United-States

-deep-sea sounding apparatus) do not show it to be

-deeper than 25,000 feet = 4 miles, 1293 yards, 1 foot. The

-deepest place in this ocean is probably between the parallels

-of 35° and 40° north latitude, and immediately to the southward

-of the Grand Banks of Newfoundland.</p>

-

-<blockquote>

-

-<p>It appears that, with one exception, the bottom of the North-Atlantic

-Ocean, as far as examined, from the depth of about sixty fathoms

-to that of more than two miles (2000 fathoms), is literally nothing but

-a mass of microscopic shells. Not one of the animalcules from these

-shells has been found living in the surface-waters, nor in shallow water

-along the shore. Hence arises the question, Do they live on the bottom,

-at the immense depths where the shells are found; or are they borne by

-submarine currents from their real habitat?</p></blockquote>

-

-<h3>RELATIVE LEVELS OF THE RED SEA AND MEDITERRANEAN.</h3>

-

-<p>The French engineers, at the beginning of the present century,

-came to the conclusion that the Red Sea was about thirty

-feet above the Mediterranean: but the observations of Mr.

-Robert Stephenson, the English engineer, at Suez; of M. Negretti,

-the Austrian, at Tineh, near the ancient Pelusium; and

-the levellings of Messrs. Talabat, Bourdaloue, and their assistants<span class="pagenum"><a name="Page_176" id="Page_176">176</a></span>

-between the two seas;&mdash;have proved that the low-water

-mark of ordinary tides at Suez and Tineh is very nearly on the

-same levels, the difference being that at Suez it is rather more

-than one inch lower.&mdash;<i>Leonard Horner</i>; <i>Proceedings of the Royal

-Society</i>, 1855.</p>

-

-<h3>THE DEPTH OF THE MEDITERRANEAN.</h3>

-

-<p>Soundings made in the Mediterranean suffice to indicate

-depths equal to the average height of the mountains girding

-round this great basin; and, if one particular experiment may

-be credited, reaching even to 15,000 feet&mdash;an equivalent to the

-elevation of the highest Alps. This sounding was made about

-ninety miles east of Malta. Between Cyprus and Egypt, 6000

-feet of line had been let down without reaching the bottom.

-Other deep soundings have been made in other places with

-similar results. In the lines of sea between Egypt and the

-Archipelago, it is stated that one sounding made by the <i>Tartarus</i>

-between Alexandria and Rhodes reached bottom at the

-depth of 9900 feet; another, between Alexandria and Candia,

-gave a depth of 300 feet beyond this. These single soundings,

-indeed, whether of ocean or sea, are always open to the certainty

-that greater as well as lesser depths must exist, to which

-no line has ever been sunk; a case coming under that general

-law of probabilities so largely applicable in every part of physics.

-In the Mediterranean especially, which has so many aspects of

-a sunken basin, there may be abysses of depth here and there

-which no plummet is ever destined to reach.&mdash;<i>Edinburgh Review.</i></p>

-

-<h3>COLOUR OF THE RED SEA.</h3>

-

-<p>M. Ehrenberg, while navigating the Red Sea, observed that

-the red colour of its waters was owing to enormous quantities

-of a new animal, which has received the name of <i>oscillatoria

-rubescens</i>, and which seems to be the same with what Haller

-has described as a <i>purple conferva</i> swimming in water; yet Dr.

-Bonar, in his work entitled <i>The Desert of Sinai</i>, records:</p>

-

-<blockquote>

-

-<p>Blue I have called the sea; yet not strictly so, save in the far distance.

-It is neither a <i>red</i> nor a <i>blue</i> sea, but emphatically green,&mdash;yes,

-green, of the most brilliant kind I ever saw. This is produced by the

-immense tracts of shallow water, with yellow sand beneath, which always

-gives this green to the sea, even in the absence of verdure on the shore

-or sea-weeds beneath. The <i>blue</i> of the sky and the <i>yellow</i> of the sands

-meeting and intermingling in the water, form the <i>green</i> of the sea; the

-water being the medium in which the mixing or fusing of the colours

-takes place.</p></blockquote>

-

-<h3>WHAT IS SEA-MILK?</h3>

-

-<p>The phenomena with this name and that of “Squid” are

-occasioned by the presence of phosphorescent animalcules. They<span class="pagenum"><a name="Page_177" id="Page_177">177</a></span>

-are especially produced in the intertropical seas, and they appear

-to be chiefly abundant in the Gulf of Guinea and in the

-Arabian Gulf. In the latter, the phenomenon was known to

-the ancients more than a century before the Christian era, as

-may be seen from a curious passage from the geography of Agatharcides:

-“Along this country (the coast of Arabia) the sea

-has a white aspect like a river: the cause of this phenomenon

-is a subject of astonishment to us.” M. Quatrefages has discovered

-that the <i>Noctilucæ</i> which produce this phenomenon do

-not always give out clear and brilliant sparks, but that under

-certain circumstances this light is replaced by a steady clearness,

-which gives in these animalcules a white colour. The

-waters in which they have been observed do not change their

-place to any sensible degree.</p>

-

-<h3>THE BOTTOM OF THE SEA A BURIAL-PLACE.</h3>

-

-<p>Among the minute shells which have been fished up from

-the great telegraphic plateau at the bottom of the sea between

-Newfoundland and Ireland, the microscope has failed to detect

-a single particle of sand or gravel; and the inference is, that

-there, if any where, the waters of the sea are at rest. There

-is not motion enough there to abrade these very delicate organisms,

-nor current enough to sweep them about and mix

-them up with a grain of the finest sand, nor the smallest particle

-of gravel from the loose beds of <i>débris</i> that here and there

-strew the bottom of the sea. The animalculæ probably do not

-live or die there. They would have had no light there; and,

-if they lived there, their frail textures would be subjected in

-their growth to a pressure upon them of a column of water

-12,000 feet high, equal to the weight of 400 atmospheres.

-They probably live and sport near the surface, where they

-can feel the genial influence of both light and heat, and are

-buried in the lichen caves below after death.</p>

-

-<p>It is now suggested, that henceforward we should view the

-surface of the sea as a nursery teeming with nascent organisms,

-and its depths as the cemetery for families of living creatures

-that outnumber the sands on the sea-shore for multitude.</p>

-

-<p>Where there is a nursery, hard by there will be found also a

-graveyard,&mdash;such is the condition of the animal world. But it

-never occurred to us before to consider the surface of the sea

-as one wide nursery, its every ripple as a cradle, and its bottom

-one vast burial-place.&mdash;<i>Lieut. Maury.</i></p>

-

-<h3>WHY IS THE SEA SALT?</h3>

-

-<p>It has been replied, In order to preserve it in a state of

-purity; which is, however, untenable, mainly from the fact that<span class="pagenum"><a name="Page_178" id="Page_178">178</a></span>

-organic impurities in a vast body of moving water, whether

-fresh or salt, become rapidly lost, so as apparently to have

-called forth a special agency to arrest the total organised matter

-in its final oscillation between the organic and inorganic worlds.

-Thus countless hosts of microscopic creatures swarm in most

-waters, their principal function being, as Professor Owen surmises,

-to feed upon and thus restore to the living chain the

-almost unorganised matter of various zones. These creatures

-preying upon one another, and being preyed upon by others in

-their turn, the circulation of organic matter is kept up. If we

-do not adopt this view, we must at least look upon the Infusoria

-and Foraminifera as scavenger agents to prevent an undue

-accumulation of decaying matter; and thus the salt condition

-of the sea is not a necessity.</p>

-

-<p>Nor is the amount of saline matter in the sea sufficient to

-arrest decomposition. That the sea is salt to render it of

-greater density, and by lowering its freezing point to preserve

-it from congelation to within a shorter distance of the poles,

-though admissible, scarcely meets the entire solution of the

-question. The freezing point of sea-water, for instance, is only

-3½° F. lower than that of fresh water; hence, with the present

-distribution of land and sea&mdash;and still less, probably, with that

-which obtained in former geological epochs&mdash;no very important

-effects would have resulted had the ocean been fresh instead of

-salt.</p>

-

-<p>Now Professor Chapman, of Toronto, suggests that the salt

-condition of the sea is mainly intended to regulate evaporation,

-and to prevent an undue excess of that phenomenon; saturated

-solutions evaporating more slowly than weak ones, and these

-latter more slowly again than pure water.</p>

-

-<p>Here, then, we have a self-adjusting phenomenon and admirable

-contrivance in the balance of forces. If from any temporary

-cause there be an unusual amount of saline matter in the

-sea, evaporation goes on the more and more slowly; and, on

-the other hand, if this proportion be reduced by the addition of

-fresh water in undue excess, the evaporating power is the more

-and more increased&mdash;thus aiding time, in either instance, to

-restore the balance. The perfect system of oceanic circulation

-may be ascribed, in a great degree at least, if not wholly, to

-the effect produced by the salts of the sea upon the mobility and

-circulation of its waters.</p>

-

-<p>Now this is an office which the sea performs in the economy

-of the universe by virtue of its saltness, and which it

-could not perform were its waters altogether fresh. And thus

-philosophers have a clue placed in their hands which will probably

-guide to one of the many hidden reasons that are embraced

-in the true answer to the question, “<i>Why is the sea salt?</i>”</p>

-

-<p><span class="pagenum"><a name="Page_179" id="Page_179">179</a></span></p>

-

-<h3>HOW TO ASCERTAIN THE SALTNESS OF THE SEA.</h3>

-

-<p>Dry a towel in the sun, weigh it carefully, and note its

-weight. Then dip it into sea-water, wring it sufficiently to

-prevent its dripping, and weigh it again; the increase of the

-weight being that of the water imbibed by the cloth. It should

-then be thoroughly dried, and once more weighed; and the excess

-of this weight above the original weight of the cloth shows

-the quantity of the salt retained by it; then, by comparing

-the weight of this salt with that of the sea-water imbibed by

-the cloth, we shall find what proportion of salt was contained

-in the water.</p>

-

-<h3>ALL THE SALT IN THE SEA.</h3>

-

-<p>The amount of common Salt in all the oceans is estimated

-by Schafhäutl at 3,051,342 cubic geographical miles. This

-would be about five times more than the mass of the Alps, and

-only one-third less than that of the Himalaya. The sulphate of

-soda equals 633,644·36 cubic miles, or is equal to the mass of

-the Alps; the chloride of magnesium, 441,811·80 cubic miles;

-the lime salts, 109,339·44 cubic miles. The above supposes the

-mean depth to be but 300 metres, as estimated by Humboldt.

-Admitting, with Laplace, that the mean depth is 1000 metres,

-which is more probable, the mass of marine salt will be more

-than double the mass of the Himalaya.&mdash;<i>Silliman’s Journal</i>,

-No. 16.</p>

-

-<p>Taking the average depth of the ocean at two miles, and

-its average saltness at 3½ per cent, it appears that there is salt

-enough in the sea to cover to the thickness of one mile an area

-of 7,000,000 of square miles. Admit a transfer of such a quantity

-of matter from an average of half a mile above to one mile

-below the sea-level, and astronomers will show by calculation

-that it would alter the length of the day.</p>

-

-<p>These 7,000,000 of cubic miles of crystal salt have not made

-the sea any fuller.</p>

-

-<h3>PROPERTIES OF SEA-WATER.</h3>

-

-<p>The solid constituents of sea-water amount to about 3½ per

-cent of its weight, or nearly half an ounce to the pound. Its

-saltness is caused as follows: Rivers which are constantly flowing

-into the ocean contain salts varying from 10 to 50, and

-even 100, grains per gallon. They are chiefly common salt,

-sulphate and carbonate of lime, magnesia,<a name="FNanchor_41" id="FNanchor_41" href="#Footnote_41" class="fnanchor">41</a> soda, potash, and

-iron; and these are found to constitute the distinguishing characteristics

-of sea-water. The water which evaporates from the<span class="pagenum"><a name="Page_180" id="Page_180">180</a></span>

-sea is nearly pure, containing but very minute traces of salts.

-Falling as rain upon the land, it washes the soil, percolates

-through the rocky layers, and becomes charged with saline

-substances, which are borne seaward by the returning currents.

-The ocean, therefore, is the great depository of every thing that

-water can dissolve and carry down from the surface of the continents;

-and as there is no channel for their escape, they consequently

-accumulate (<i>Youmans’ Chemistry</i>). They would constantly

-accumulate, as this very shrewd author remarks, were

-it not for the shells and insects of the sea and other agents.</p>

-

-<h3>SCENERY AND LIFE OF THE ARCTIC REGIONS.</h3>

-

-<p>The late Dr. Scoresby, from personal observations made in

-the course of twenty-one voyages to the Arctic Regions, thus

-describes these striking characteristics:</p>

-

-<blockquote>

-

-<p>The coast scenes of Greenland are generally of an abrupt character,

-the mountains frequently rising in triangular profile; so much so, that

-it is sometimes not possible to effect their ascent. One of the most

-notable characteristics of the Arctic lands is the deception to which travellers

-are liable in regard to distances. The occasion of this is the

-quantity of light reflected from the snow, contrasted with the dark colour

-of the rocks. Several persons of considerable experience have been

-deceived in this way, imagining, for example, that they were close to

-the shore when in fact they were more than twenty miles off. The trees

-of these lands are not more than three inches above ground.</p>

-

-<p>Many of the icebergs are five miles in extent, and some are to be

-seen running along the shore measuring as much as thirteen miles. Dr.

-Scoresby has seen a cliff of ice supported on those floating masses 402

-feet in height. There is no place in the world where animal life is to

-be found in greater profusion than in Greenland, Spitzbergen, Baffin’s

-Bay, and other portions of the Arctic regions. This is to be accounted

-for by the abundance and richness of the food supplied by the sea. The

-number of birds is especially remarkable. On one occasion, no less

-than a million of little hawks came in sight of Dr. Scoresby’s ship within

-a single hour.</p>

-

-<p>The various phenomena of the Greenland sea are very interesting.

-The different colours of the sea-water&mdash;olive or bottle-green, reddish-brown,

-and mustard&mdash;have, by the aid of the microscope, been found

-to be owing to animalculæ of these various colours: in a single drop of

-mustard-coloured water have been counted 26,450 animals. Another

-remarkable characteristic of the Greenland sea-water is its warm temperature&mdash;one,

-two, and three degrees above the freezing-point even in

-the cold season. This Dr. Scoresby accounts for by supposing the flow

-in that direction of warm currents from the south. The polar fields of

-ice are to be found from eight or nine to thirty or forty feet in thickness.

-By fastening a hook twelve or twenty inches in these masses of

-ice, a ship could ride out in safety the heaviest gales.</p></blockquote>

-

-<h3>ICEBERG OF THE POLAR SEAS.</h3>

-

-<p>The ice of this berg, although opaque and vascular, is true

-glacier ice, having the fracture, lustre, and other external characters<span class="pagenum"><a name="Page_181" id="Page_181">181</a></span>

-of a nearly homogeneous growth. The iceberg is true

-ice, and is always dreaded by ships. Indeed, though modified

-by climate, and especially by the alternation of day and night,

-the polar glacier must be regarded as strictly atmospheric in

-its increments, and not essentially differing from the glacier of

-the Alps. The general appearance of a berg may be compared

-to frosted silver; but when its fractures are very extensive,

-the exposed faces have a very brilliant lustre. Nothing can be

-more exquisite than a fresh, cleanly fractured berg surface: it

-reminds one of the recent cleavage of sulphate of strontian&mdash;a

-resemblance more striking from the slightly lazulitic tinge of

-each.&mdash;<i>U.&nbsp;S. Grinnel Expedition in Search of Sir J. Franklin.</i></p>

-

-<h3>IMMENSITY OF POLAR ICE.</h3>

-

-<p>The quantity of solid matter that is drifted out of the

-Polar Seas through one opening&mdash;Davis’s Straits&mdash;alone, and

-during a part of the year only, covers to the depth of seven

-feet an area of 300,000 square miles, and weighs not less than

-18,000,000,000 tons. The quantity of water required to float

-and drive out this solid matter is probably many times greater

-than this. A quantity of water equal in weight to these two

-masses has to go in. The basin to receive these inflowing waters,

-<i>i. e.</i> the unexplored basin about the North Pole, includes

-an area of 1,500,000 square miles; and as the outflowing ice

-and water are at the surface, the return current must be submarine.</p>

-

-<p>These two currents, therefore, it may be perceived, keep in

-motion between the temperate and polar regions of the earth a

-volume of water, in comparison with which the mighty Mississippi

-in its greatest floods sinks down to a mere rill.&mdash;<i>Maury.</i></p>

-

-<h3>OPEN SEA AT THE POLE.</h3>

-

-<p>The following fact is striking: In 1662&ndash;3, Mr. Oldenburg,

-Secretary to the Royal Society, was ordered to register a paper

-entitled “Several Inquiries concerning Greenland, answered by

-Mr. Gray, who had visited those parts.” The nineteenth query

-was, “How near any one hath been known to approach the Pole.

-<i>Answer.</i> I once met upon the coast of Greenland a Hollander,

-that swore he had been but half a degree from the Pole, showing

-me his journal, which was also attested by his mate; where

-<i>they had seen no ice or land, but all water</i>.” Boyle mentions

-a similar account, which he received from an old Greenland

-master, on April 5, 1765.</p>

-

-<h3>RIVER-WATER ON THE OCEAN.</h3>

-

-<p>Captain Sabine found discoloured water, supposed to be

-that of the Amazon, 300 miles distant in the ocean from the<span class="pagenum"><a name="Page_182" id="Page_182">182</a></span>

-embouchure of that river. It was about 126 feet deep. Its specific

-gravity was = 1·0204, and the specific gravity of the sea-water

-= 1·0262. This appears to be the greatest distance from

-land at which river-water has been detected on the surface of

-the ocean. It was estimated to be moving at the rate of three

-miles an hour, and had been turned aside by an ocean-current.

-“It is not a little curious to reflect,” says Sir Henry de la Beche,

-“that the agitation and resistance of its particles should be sufficient

-to keep finely comminuted solid matter mechanically

-suspended, so that it would not be disposed freely to part with

-it except at its junction with the sea-water over which it flows,

-and where, from friction, it is sufficiently retarded.”</p>

-

-<h3>THE THAMES AND ITS SALT-WATER BED.</h3>

-

-<p>The Thames below Woolwich, in place of flowing upon a

-solid bottom, really flows upon the liquid bottom formed by

-the water of the sea. At the flow of the tide, the fresh water

-is raised, as it were, in a single mass by the salt water which

-flows in, and which ascends the bed of the river, while the fresh

-water continues to flow towards the sea.&mdash;<i>Mr. Stevenson, in

-Jameson’s Journal.</i></p>

-

-<h3>FRESH SPRINGS IN THE MIDDLE OF THE OCEAN.</h3>

-

-<p>On the southern coast of the island of Cuba, at a few miles

-from land, Springs of Fresh Water gush from the bed of the

-Ocean, probably under the influence of hydrostatic pressure, and

-rise through the midst of the salt water. They issue forth with

-such force that boats are cautious in approaching this locality,

-which has an ill repute on account of the high cross sea thus

-caused. Trading vessels sometimes visit these springs to take

-in a supply of fresh water, which is thus obtained in the open

-sea. The greater the depth from which the water is taken,

-the fresher it is found to be.</p>

-

-<h3>“THE BLACK WATERS.”</h3>

-

-<p>In the upper portion of the basin of the Orinoco and its

-tributaries, Nature has several times repeated the enigmatical

-phenomenon of the so-called “Black Waters.” The Atabapo,

-whose banks are adorned with Carolinias and arborescent Melastomas,

-is a river of a coffee-brown colour. In the shade of

-the palm-groves this colour seems about to pass into ink-black.

-When placed in transparent vessels, the water appears of a golden

-yellow. The image of the Southern Constellation is reflected

-with wonderful clearness in these black streams. When their

-waters flow gently, they afford to the observer, when taking

-astronomical observations with reflecting instruments, a most

-excellent artificial horizon. These waters probably owe their<span class="pagenum"><a name="Page_183" id="Page_183">183</a></span>

-peculiar colour to a solution of carburetted hydrogen, to the

-luxuriance of the tropical vegetation, and to the quantity of

-plants and herbs on the ground over which they flow.&mdash;<i>Humboldt’s

-Aspects of Nature</i>, vol. i.</p>

-

-<h3>GREAT CATARACT IN INDIA.</h3>

-

-<p>Where the river Shirhawti, between Bombay and Cape Comorin,

-falls into the Gulf of Arabia, it is about one-fourth of a

-mile in width, and in the rainy season some thirty feet in depth.

-This immense body of water rushes down a rocky slope 300 feet,

-at an angle of 45°, at the bottom of which it makes a perpendicular

-plunge of 850 feet into a black and dismal abyss, with

-a noise like the loudest thunder. The whole descent is therefore

-1150 feet, or several times that of Niagara; but the volume

-of water in the latter is somewhat larger than in the former.</p>

-

-<h3>CAUSE OF WAVES.</h3>

-

-<p>The friction of the wind combines with the tide in agitating

-the surface of the ocean, and, according to the theory of undulations,

-each produces its effect independently of the other.

-Wind, however, not only raises waves, but causes a transfer of

-superficial water also. Attraction between the particles of air

-and water, as well as the pressure of the atmosphere, brings its

-lower stratum into adhesive contact with the surface of the sea.

-If the motion of the wind be parallel to the surface, there will

-still be friction, but the water will be smooth as a mirror; but

-if it be inclined, in however small a degree, a ripple will appear.

-The friction raises a minute wave, whose elevation protects the

-water beyond it from the wind, which consequently impinges

-on the surface at a small angle: thus each impulse, combining

-with the other, produces an undulation which continually advances.&mdash;<i>Mrs.

-Somerville’s Physical Geography.</i></p>

-

-<h3>RATE AT WHICH WAVES TRAVEL.</h3>

-

-<p>Professor Bache states, as one of the effects of an earthquake

-at Simoda, on the island of Niphon, in Japan, that the harbour

-was first emptied of water, and then came in an enormous wave,

-which again receded and left the harbour dry. This occurred

-several times. The United-States self-acting tide-gauge at San

-Francisco, which records the rise of the tide upon cylinders

-turned by clocks, showed that at San Francisco, 4800 miles from

-the scene of the earthquake, the first wave arrived twelve hours

-and sixteen minutes after it had receded from the harbour of

-Simoda. It had travelled across the broad bosom of the Pacific

-Ocean at the rate of six miles and a half a minute, and arrived

-on the shores of California: the first wave being seven-tenths of<span class="pagenum"><a name="Page_184" id="Page_184">184</a></span>

-a foot in height, and lasting for about half an hour, followed by

-seven lesser waves, at intervals of half an hour each.</p>

-

-<p>The velocity with which a wave travels depends on the depth

-of the ocean. The latest calculations for the Pacific Ocean give

-a depth of from 14,000 to 18,000 fathoms. It is remarkable

-how the estimates of the ocean’s depth have grown less. Laplace

-assumed it at ten miles, Whewell at 3·5, while the above

-estimate brings it down to two miles.</p>

-

-<p>Mr. Findlay states, that the dynamic force exerted by Sea-Waves

-is greatest at the crest of the wave before it breaks; and

-its power in raising itself is measured by various facts. At

-Wasburg, in Norway, in 1820, it rose 400 feet; and on the

-coast of Cornwall, in 1843, 300 feet. The author shows that

-waves have sometimes raised a column of water equivalent to

-a pressure of from three to five tons the square foot. He also

-proves that the velocity of the waves depends on their length,

-and that waves of from 300 to 400 feet in length from crest to

-crest travel from twenty to twenty-seven and a half miles an

-hour. Waves travel great distances, and are often raised by

-distant hurricanes, having been felt simultaneously at St. Helena

-and Ascension, though 600 miles apart; and it is probable

-that ground-swells often originate at the Cape of Good Hope,

-3000 miles distant. Dr. Scoresby found the travelling rate of

-the Atlantic waves to be 32·67 English statute miles per hour.</p>

-

-<p>In the winter of 1856, a heavy ground-swell, brought on by

-five hours’ gale, scoured away in fourteen hours 3,900,000 tons

-of pebbles from the coast near Dover; but in three days, without

-any shift of wind, upwards of 3,000,000 tons were thrown

-back again. These figures are to a certain extent conjectural;

-but the quantities have been derived from careful measurement

-of the profile of the beach.</p>

-

-<h3>OCEAN-HIGHWAYS: HOW SEA-ROUTES HAVE BEEN

-SHORTENED.</h3>

-

-<p>When one looks seaward from the shore, and sees a ship

-disappear in the horizon as she gains an offing on a voyage to

-India, or the Antipodes perhaps, the common idea is that she

-is bound over a trackless waste; and the chances of another

-ship sailing with the same destination the next day, or the

-next week, coming up and speaking with her on the “pathless

-ocean,” would to most minds seem slender indeed. Yet

-the truth is, the winds and the currents are now becoming so

-well understood, that the navigator, like the backwoodsman

-in the wilderness, is enabled literally to “blaze his way” across

-the ocean; not, indeed, upon trees, as in the wilderness, but

-upon the wings of the wind. The results of scientific inquiry<span class="pagenum"><a name="Page_185" id="Page_185">185</a></span>

-have so taught him how to use these invisible couriers, that

-they, with the calm belts of the air, serve as sign-boards to

-indicate to him the turnings and forks and crossings by the

-way.</p>

-

-<blockquote>

-

-<p>Let a ship sail from New York to California, and the next week let

-a faster one follow; they will cross each other’s path many times, and

-are almost sure to see each other by the way, as in the voyage of two

-fine clipper-ships from New York to California. On the ninth day after

-the <i>Archer</i> had sailed, the <i>Flying Cloud</i> put to sea. Both ships were

-running against time, but without reference to each other. The <i>Archer</i>,

-with wind and current charts in hand, went blazing her way across the

-calms of Cancer, and along the new route down through the north-east

-trades to the equator; the <i>Cloud</i> followed, crossing the equator upon

-the trail of Thomas of the <i>Archer</i>. Off Cape Horn she came up with him,

-spoke him, and handed him the latest New York dates. The <i>Flying

-Cloud</i> finally ranged ahead, made her adieus, and disappeared among

-the clouds that lowered upon the western horizon, being destined to

-reach her port a week or more in advance of her Cape Horn consort.

-Though sighting no land from the time of their separation until they

-gained the offing of San Francisco,&mdash;some six or eight thousand miles

-off,&mdash;the tracks of the two vessels were so nearly the same, that being

-projected upon the chart, they appear almost as one.</p>

-

-<p>This is the great course of the ocean: it is 15,000 miles in length.

-Some of the most glorious trials of speed and of prowess that the world

-ever witnessed among ships that “walk the waters” have taken place

-over it. Here the modern clipper-ship&mdash;the noblest work that has ever

-come from the hands of man&mdash;has been sent, guided by the lights of

-science, to contend with the elements, to outstrip steam, and astonish

-the world.&mdash;<i>Maury.</i></p></blockquote>

-

-<h3>ERROR UPON ERROR.</h3>

-

-<p>The great inducement to Mr. Babbage, some years since, to

-attempt the construction of a machine by which astronomical

-tables could be calculated and even printed by mechanical

-means, and with entire accuracy, was the errors in the requisite

-tables. Nineteen such errors, in point of fact, were discovered

-in an edition of Taylor’s <i>Logarithms</i> printed in 1796;

-some of which might have led to the most dangerous results in

-calculating a ship’s place. These nineteen errors (of which one

-only was an error of the press) were pointed out in the <i>Nautical

-Almanac</i> for 1832. In one of these <i>errata</i>, the seat of the

-error was stated to be in cosine of 14° 18′ 3″. Subsequent

-examination showed that there was an error of one second in

-this correction, and accordingly, in the <i>Nautical Almanac</i> of

-the next year a new correction was necessary. But in making

-the new correction of one second, a new error was committed

-of ten degrees, making it still necessary, in some future edition

-of the <i>Nautical Almanac</i>, to insert an <i>erratum</i> in an <i>erratum</i> of

-the <i>errata</i> in Taylor’s <i>Logarithms</i>.&mdash;<i>Edinburgh Review</i>, vol. 59.</p>

-

-<hr />

-

-<p><span class="pagenum"><a name="Page_186" id="Page_186">186</a></span></p>

-

-<div class="chapter"></div>

-<h2><a name="Phenomena" id="Phenomena"></a>Phenomena of Heat.</h2>

-

-<h3>THE LENGTH OF THE DAY AND THE HEAT OF THE EARTH.</h3>

-

-<p>As we may judge of the uniformity of temperature from the

-unaltered time of vibration of a pendulum, so we may also

-learn from the unaltered rotatory velocity of the earth the

-amount of stability in the mean temperature of our globe.

-This is the result of one of the most brilliant applications of

-the knowledge we had long possessed of the movement of the

-heavens to the thermic condition of our planet. The rotatory

-velocity of the earth depends on its volume; and since, by the

-gradual cooling of the mass by radiation, the axis of rotation

-would become shorter, the rotatory velocity would necessarily

-increase, and the length of the day diminish with a decrease of

-the temperature. From the comparison of the secular inequalities

-in the motions of the moon with the eclipses observed in

-former ages, it follows that, since the time of Hipparchus,&mdash;that

-is, for full 2000 years,&mdash;the length of the day has certainly not

-diminished by the hundredth part of a second. The decrease

-of the mean heat of the globe during a period of 2000 years has

-not therefore, taking the extremest limits, diminished as much

-as 1/306th of a degree of Fahrenheit.<a name="FNanchor_42" id="FNanchor_42" href="#Footnote_42" class="fnanchor">42</a>&mdash;<i>Humboldt’s Cosmos</i>, vol. i.</p>

-

-<h3>NICE MEASUREMENT OF HEAT.</h3>

-

-<p>A delicate thermometer, placed on the ground, will be affected

-by the passage of a single cloud across a clear sky; and

-if a succession of clouds pass over, with intervals of clear sky

-between them, such an instrument has been observed to fluctuate

-accordingly, rising with each passing mass of vapour, and

-falling again when the radiation becomes unrestrained.</p>

-

-<h3>EXPENDITURE OF HEAT BY THE SUN.</h3>

-

-<p>Sir John Herschel estimates the total Expenditure of Heat

-by the Sun in a given time, by supposing a cylinder of ice 45

-miles in diameter to be continually darted into the sun <i>with

-the velocity of light</i>, and that the water produced by its fusion

-were continually carried off: the heat now given off constantly<span class="pagenum"><a name="Page_187" id="Page_187">187</a></span>

-by radiation would then be wholly expended in its

-liquefaction, on the one hand, so as to leave no radiant surplus;

-while, on the other, the actual temperature at its surface would

-undergo no diminution.</p>

-

-<p>The great mystery, however, is to conceive how so enormous

-a conflagration (if such it be) can be kept up. Every

-discovery in chemical science here leaves us completely at a

-loss, or rather seems to remove further the prospect of probable

-explanation. If conjecture might be hazarded, we should look

-rather to the known possibility of an indefinite generation of

-heat by friction, or to its excitement by the electric discharge,

-than to any combustion of ponderable fuel, whether solid or

-gaseous, for the origin of the solar radiation.&mdash;<i>Outlines.</i><a name="FNanchor_43" id="FNanchor_43" href="#Footnote_43" class="fnanchor">43</a></p>

-

-<h3>DISTINCTIONS OF HEAT.</h3>

-

-<p>Among the curious laws of modern science are those which

-regulate the transmission of radiant heat through transparent

-bodies. The heat of our fires is intercepted and detained by

-screens of glass, and, being so detained, warms them; while

-solar heat passes freely through and produces no such effect.

-“The more recent researches of Delaroche,” says Sir John Herschel,

-“however, have shown that this detention is complete

-only when the temperature of the source of heat is low; but

-that as the temperature gets higher a portion of the heat radiated

-acquires a power of penetrating glass, and that the

-quantity which does so bears continually a larger and larger proportion

-to the whole, as the heat of the radiant body is more

-intense. This discovery is very important, as it establishes a

-community of nature between solar and terrestrial heat; while

-at the same time it leads us to regard the actual temperature of

-the sun as far exceeding that of any earthly flame.”</p>

-

-<h3>LATENT HEAT.</h3>

-

-<p>This extraordinary principle exists in all bodies, and may

-be pressed out of them. The blacksmith hammers a nail until

-it becomes red hot, and from it he lights the match with which

-he kindles the fire of his forge. The iron has by this process

-become more dense, and percussion will not again produce incandescence

-until the bar has been exposed in fire to a red heat,

-when it absorbs heat, the particles are restored to their former

-state, and we can again by hammering develop both heat and

-light.&mdash;<i>R. Hunt, F.R.S.</i></p>

-

-<p><span class="pagenum"><a name="Page_188" id="Page_188">188</a></span></p>

-

-<h3>HEAT AND EVAPORATION.</h3>

-

-<p>In a communication made to the French Academy, M.

-Daubrée calculates that the Evaporation of the Water on the

-surface of the globe employs a quantity of heat about equal to

-one-third of what is received from the sun; or, in other words,

-equal to the melting of a bed of ice nearly thirty-five feet in

-thickness if spread over the globe.</p>

-

-<h3>HEAT AND MECHANICAL POWER.</h3>

-

-<p>It has been found that Heat and Mechanical Power are

-mutually convertible; and that the relation between them is

-definite, 772 foot-pounds of motive power being equivalent to

-a unit of heat, that is, to the amount of heat requisite to raise a

-pound of water through one degree of Fahrenheit.</p>

-

-<h3>HEAT OF MINES.</h3>

-

-<p>One cause of the great Heat of many of our deep Mines,

-which appears to have been entirely lost sight of, is the chemical

-action going on upon large masses of pyritic matter in their

-vicinity. The heat, which is so oppressive in the United Mines

-in Cornwall that the miners work nearly naked, and bathe in

-water at 80° to cool themselves, is without doubt due to the

-decomposition of immense quantities of the sulphurets of iron

-and copper known to be in this condition at a short distance

-from these mineral works.&mdash;<i>R. Hunt, F.R.S.</i></p>

-

-<h3>VIBRATION OF HEATED METALS.</h3>

-

-<p>Mr. Arthur Trevelyan discovered accidentally that a bar of

-iron, when heated and placed with one end on a solid block

-of lead, in cooling vibrates considerably, and produces sounds

-similar to those of an Æolian harp. The same effect is produced

-by bars of copper, zinc, brass, and bell-metal, when

-heated and placed on blocks of lead, tin, or pewter. The bars

-were four inches long, one inch and a half wide, and three-eighths

-of an inch thick.</p>

-

-<p>The conditions essential to these experiments are, That two

-different metals must be employed&mdash;the one soft and possessed

-of moderate conducting powers, viz. lead or tin, the other hard;

-and it matters not whether soft metal be employed for the bar

-or block, provided the soft metal be cold and the hard metal

-heated.</p>

-

-<p>That the surface of the block shall be uneven, for when rendered

-quite smooth the vibration does not take place; but the

-bar cannot be too smooth.</p>

-

-<p>That no matter be interposed, else it will prevent vibration,<span class="pagenum"><a name="Page_189" id="Page_189">189</a></span>

-with the exception of a burnish of gold leaf, the thickness of

-which cannot amount to the two-hundred-thousandth part of

-an inch.&mdash;<i>Transactions of the Royal Society of Edinburgh.</i></p>

-

-<h3>EXPANSION OF SPIRITS.</h3>

-

-<p>Spirits expand and become lighter by means of heat in a

-greater proportion than water, wherefore they are heaviest in

-winter. A cubic inch of brandy has been found by many experiments

-to weigh ten grains more in winter than in summer,

-the difference being between four drams thirty-two grains and

-four drams forty-two grains. Liquor-merchants take advantage

-of this circumstance, and make their purchases in winter

-rather than in summer, because they get in reality rather a

-larger quantity in the same bulk, buying by measure.&mdash;<i>Notes in

-Various Sciences.</i></p>

-

-<h3>HEAT PASSING THROUGH GLASS.</h3>

-

-<p>The following experiment is by Mr. Fox Talbot: Heat a

-poker bright-red hot, and having opened a window, apply the

-poker quickly very near to the outside of a pane, and the hand

-to the inside; a strong heat will be felt at the instant, which

-will cease as soon as the poker is withdrawn, and may be again

-renewed and made to cease as quickly as before. Now it is

-well known, that if a piece of glass is so much warmed as to

-convey the impression of heat to the hand, it will retain some

-part of that heat for a minute or more; but in this experiment

-the heat will vanish in a moment: it will not, therefore, be the

-heated pane of glass that we shall feel, but heat which has come

-through the glass in a free or radiant state.</p>

-

-<h3>HEAT FROM GAS-LIGHTING.</h3>

-

-<p>In the winter of 1835, Mr. W.&nbsp;H. White ascertained the temperature

-in the City to be 3° higher than three miles south of

-London Bridge; and <i>after the gas had been lighted in the City</i>

-four or five hours the temperature increased full 3°, thus making

-6° difference in the three miles.</p>

-

-<h3>HEAT BY FRICTION.</h3>

-

-<p>Friction as a source of Heat is well known: we rub our

-hands to warm them, and we grease the axles of carriage-wheels

-to prevent their setting fire to the wood. Count Rumford

-has established the extraordinary fact, that an unlimited supply

-of heat may be derived from friction by the same materials:

-he made great quantities of water boil by causing a blunt borer

-to rub against a mass of metal immersed in the water. Savages

-light their fires by rubbing two pieces of wood: the <i>modus operandi</i>,<span class="pagenum"><a name="Page_190" id="Page_190">190</a></span>

-as practised by the Kaffirs of South Africa, is thus described

-by Captain Drayton:</p>

-

-<blockquote>

-

-<p>Two dry sticks, one being of hard and the other of soft wood, were

-the materials used. The soft stick was laid on the ground, and held

-firmly down by one Kaffir, whilst another employed himself in scooping

-out a little hole in the centre of it with the point of his assagy: into this

-little hollow the end of the hard wood was placed, and held vertically.

-These two men sat face to face, one taking the vertical stick between

-the palms of his hands, and making it twist about very quickly, while

-the other Kaffir held the lower stick firmly in its place; the friction

-caused by the end of one piece of wood revolving upon the other soon

-made the two pieces smoke. When the Kaffir who twisted became tired,

-the respective duties were exchanged. These operations having continued

-about a couple of minutes, sparks began to appear, and when they

-became numerous, were gathered into some dry grass, which was then

-swung round at arm’s length until a blaze was established; and a roaring

-fire was gladdening the hearts of the Kaffirs with the anticipation of

-a glorious feast in about ten minutes from the time that the operation

-was first commenced.</p></blockquote>

-

-<h3>HEAT BY FRICTION FROM ICE.</h3>

-

-<p>When Sir Humphry Davy was studying medicine at Penzance,

-one of his constant associates was Mr. Tom Harvey, a

-druggist in the above town. They constantly experimented together;

-and one severe winter’s day, after a discussion on the

-nature of heat, the young philosophers were induced to go to

-Larigan river, where Davy succeeded in developing heat by <i>rubbing

-two pieces of ice together</i> so as to melt each other;<a name="FNanchor_44" id="FNanchor_44" href="#Footnote_44" class="fnanchor">44</a> an experiment

-which he repeated with much <i>éclat</i> many years after,

-in the zenith of his celebrity, at the Royal Institution. The

-pieces of ice for this experiment are fastened to the ends of two

-sticks, and rubbed together in air below the temperature of

-32°: this Davy readily accomplished on the day of severe cold

-at the Larigan river; but when the experiment was repeated at

-the Royal Institution, it was in the vacuum of an air-pump,

-when the temperature of the apparatus and of the surrounding

-air was below 32°. It was remarked, that when the surface

-of the rubbing pieces was rough, only half as much heat was

-evolved as when it was smooth. When the pressure of the rubbing

-piece was increased four times, the proportion of heat

-evolved was increased sevenfold.</p>

-

-<h3>WARMING WITH ICE.</h3>

-

-<p>In common language, any thing is understood to be cooled

-or warmed when the temperature thereof is made higher or

-lower, whatever may have been the temperature when the

-change was commenced. Thus it is said that melted iron is<span class="pagenum"><a name="Page_191" id="Page_191">191</a></span>

-<i>cooled</i> down to a sub-red heat, or mercury is cooled from the

-freezing point to zero, or far below. By the same rule, solid

-mercury, say 50° below zero, may, in any climate or temperature

-of the atmosphere, be immediately warmed and melted by

-being imbedded in a cake of ice.&mdash;<i>Scientific American.</i></p>

-

-<h3>REPULSION BY HEAT.</h3>

-

-<p>If water is poured upon an iron sieve, the wires of which

-are made red-hot, it will not run through; but on cooling, it

-will pass through rapidly. M. Boutigny, pursuing this curious

-inquiry, has proved that the moisture upon the skin is sufficient

-to protect it from disorganisation if the arm is plunged into

-baths of melted metal. The resistance of the surfaces is so great

-that little elevation of temperature is experienced. Professor

-Plücker has stated, that by washing the arm with ether previously

-to plunging it into melted metal, the sensation produced

-while in the molten mass is that of freezing coldness.&mdash;<i>R.

-Hunt, F.R.S.</i></p>

-

-<h3>PROTECTION FROM INTENSE HEAT.</h3>

-

-<p>The singular power which the body possesses of resisting

-great heats, and of breathing air of high temperatures, has at

-various times excited popular wonder. In the last century

-some curious experiments were made on this subject. Sir

-Joseph Banks, Dr. Solander, and Sir Charles Blagden, entered

-a room in which the air had a temperature of 198° Fahr., and

-remained ten minutes. Subsequently they entered the room

-separately, when Dr. Solander found the heat 210°, and Sir

-Joseph 211°, whilst their bodies preserved their natural degree

-of heat. Whenever they breathed upon a thermometer, it sank

-several degrees; every inspiration gave coolness to their nostrils,

-and their breath cooled their fingers when it reached them. Sir

-Charles Blagden entered an apartment when the heat was 1°

-or 2° above 260°, and remained eight minutes, mostly on the

-coolest spot, where the heat was above 240°. Though very hot,

-Sir Charles felt no pain: during seven minutes his breathing

-was good; but he then felt an oppression in his lungs, and his

-pulse was 144, double its ordinary quickness. To prove the

-heat of the room, eggs and a beefsteak were placed upon a tin

-frame near the thermometer, when in twenty minutes the eggs

-were roasted hard, and in forty-seven minutes the steak was

-dressed dry; and when the air was put in motion by a pair of

-bellows upon another steak, part of it was well done in thirteen

-minutes. It is remarkable, that in these experiments the same

-person who experienced no inconvenience from air heated to

-211°, could just bear rectified spirits of wine at 130°, cooling oil

-at 129°, cooling water at 123°, and cooling quicksilver at 117°.</p>

-

-<p><span class="pagenum"><a name="Page_192" id="Page_192">192</a></span>

-Sir Francis Chantrey, the sculptor, however, exposed himself

-to a temperature still higher than any yet mentioned, as described

-by Sir David Brewster:</p>

-

-<blockquote>

-

-<p>The furnace which he employs for drying his moulds is about fourteen

-feet long, twelve feet high, and twelve feet broad. When it is raised to

-its highest temperature, with the doors closed, the thermometer stands

-at 350°, and the iron floor is red-hot. The workmen often enter it at

-a temperature of 340°, walking over the iron floor with wooden clogs,

-which are of course charred on the surface. On one occasion, Mr. Chantrey,

-accompanied by five or six of his friends, entered the furnace; and

-after remaining two minutes they brought out a thermometer which

-stood at 320°. Some of the party experienced sharp pains in the tips

-of their ears and in the septum of the nose, while others felt a pain in

-their eyes.&mdash;<i>Natural Magic</i>, 1833.</p></blockquote>

-

-<p>In some cases the clothing worn by the experimenters conducts

-away the heat. Thus, in 1828, a Spaniard entered a heated

-oven, at the New Tivoli, near Paris; he sang a song while a

-fowl was roasted by his side, he then ate the fowl and drank a

-bottle of wine, and on coming out his pulse beat 176°, and the

-thermometer was at 110° Reaumur. He then stretched himself

-upon a plank in the oven surrounded by lighted candles,

-when the mouth of the oven was closed; he remained there

-five minutes, and on being taken out, all the candles were extinguished

-and melted, and the Spaniard’s pulse beat 200°.

-Now much of the surprise ceases when it is added that he

-wore wide woollen pantaloons, a loose mantle of wool, and a

-great quilted cap; the several materials of this clothing being

-bad conductors of heat.</p>

-

-<p>In 1829 M. Chabert, the “Fire-King,” exhibited similar

-feats at the Argyll Rooms in Regent Street. He first swallowed

-forty grains of phosphorus, then two spoonfuls of oil at

-330°, and next held his head over the fumes of sulphuric acid.

-He had previously provided himself with an antidote for the

-poison of the phosphorus. Dressed in a loose woollen coat, he

-then entered a heated oven, and in five minutes cooked two

-steaks; he then came out of the oven, when the thermometer

-stood at 380°. Upon another occasion, at White Conduit House,

-some of his feats were detected.</p>

-

-<p>The scientific secret is as follows: Muscular tissue is an

-extremely bad conductor; and to this in a great measure the

-constancy of the temperature of the human body in various

-zones is to be attributed. To this fact also Sir Charles Blagden

-and Chantrey owed their safety in exposing their bodies to

-a high temperature; from the almost impervious character of

-the tissues of the body, the irritation produced was confined to

-the surface.</p>

-

-<hr />

-

-<p><span class="pagenum"><a name="Page_193" id="Page_193">193</a></span></p>

-

-<div class="chapter"></div>

-<h2><a name="Magnetism" id="Magnetism"></a>Magnetism and Electricity.</h2>

-

-<h3>MAGNETIC HYPOTHESES.</h3>

-

-<p>As an instance of the obstacles which erroneous hypotheses

-throw in the way of scientific discovery, Professor Faraday adduces

-the unsuccessful attempts that had been made in England

-to educe Magnetism from Electricity until Oersted showed

-the simple way. Faraday relates, that when he came to the

-Royal Institution as an assistant in the laboratory, he saw

-Davy, Wollaston, and Young trying, by every way that suggested

-itself to them, to produce magnetic effects from an electric

-current; but having their minds diverted from the true

-course by their existing hypotheses, it did not occur to them

-to try the effect of holding a wire through which an electric

-current was passing over a suspended magnetic needle. Had

-they done so, as Oersted afterwards did, the immediate deflection

-of the needle would have proved the magnetic property

-of an electric current. Faraday has shown that the magnetism

-of a steel bar is caused by the accumulated action of all the

-particles of which it is composed: this he proves by first magnetising

-a small steel bar, and then breaking it successively

-into smaller and smaller pieces, each one of which possesses a

-separate pole; and the same operation may be continued until

-the particles become so small as not to be distinguishable without

-a microscope.</p>

-

-<p>We quote the above from a late Number of the <i>Philosophical

-Magazine</i>, wherein also we find the following noble tribute to

-the genius and public and private worth of Faraday:</p>

-

-<blockquote>

-

-<p>The public never can know and appreciate the national value of such

-a man as Faraday. He does not work to please the public, nor to win

-its guineas; and the said public, if asked its opinion as to the practical

-value of his researches, can see no possible practical issue there. The

-public does not know that we need prophets more than mechanics in

-science,&mdash;inspired men, who, by patient self-denial and the exercise of

-the high intellectual gifts of the Creator, bring us intelligence of His

-doings in Nature. To them their pursuits are good in themselves. Their

-chief reward is the delight of being admitted into communion with Nature,

-the pleasure of tracing out and proclaiming her laws, wholly forgetful

-whether those laws will ever augment our banker’s account or

-improve our knowledge of cookery. <i>Such men, though not honoured by

-the title of “practical,” are they which make practical men possible.</i> They

-bring us the tamed forces of Nature, and leave it to others to contrive

-the machinery to which they may be yoked. If we are rightly informed,

-it was Faradaic electricity which shot the glad tidings of the fall of Sebastopol

-from Balaklava to Varna. Had this man converted his talent<span class="pagenum"><a name="Page_194" id="Page_194">194</a></span>

-to commercial purposes, as so many do, we should not like to set a limit

-to his professional income. The quality of his services cannot be expressed

-by pounds; but that brave body, which for forty years has been

-the instrument of that great soul, is a fit object for a nation’s care, as

-the achievements of the man are, or will one day be, the object of a

-nation’s pride and gratitude.</p></blockquote>

-

-<h3>THE CHINESE AND THE MAGNETIC NEEDLE.</h3>

-

-<p>More than a thousand years before our era, a people living

-in the extremest eastern portions of Asia had magnetic carriages,

-on which the movable arm of the figure of a man continually

-pointed to the south, as a guide by which to find the

-way across the boundless grass-plains of Tartary; nay, even in

-the third century of our era, therefore at least 700 years before

-the use of the mariner’s compass in European seas, Chinese

-vessels navigated the Indian Ocean under the direction of

-Magnetic Needles pointing to the south.</p>

-

-<blockquote>

-

-<p>Now the Western nations, the Greeks and the Romans, knew that

-magnetism could be communicated to iron, and <i>that that metal</i> would

-retain it for a length of time. The great discovery of the terrestrial

-directive force depended, therefore, alone on this&mdash;that no one in the

-West had happened to observe an elongated fragment of magnetic iron-stone,

-or a magnetic iron rod, floating by the aid of a piece of wood in

-water, or suspended in the air by a thread, in such a position as to admit

-of free motion.&mdash;<i>Humboldt’s Cosmos</i>, vol. i.</p></blockquote>

-

-<h3>KIRCHER’S “MAGNETISM.”</h3>

-

-<p>More than two centuries since, Athanasius Kircher published

-his strange book on Magnetism, in which he anticipated

-the supposed virtue of magnetic traction in the curative art,

-and advocated the magnetism of the sun and moon, of the

-divining-rod, and showed his firm belief in animal magnetism.

-“In speaking of the vegetable world,” says Mr. Hunt, “and

-the remarkable processes by which the leaf, the flower, and the

-fruit are produced, this sage brings forward the fact of the

-diamagnetic (repelled by the magnet) character of the plant

-which was in 1852 rediscovered; and he refers the motions of

-the sunflower, the closing of the convolvulus, and the directions

-of the spiral formed by the twining plants, to this particular

-influence.”<a name="FNanchor_45" id="FNanchor_45" href="#Footnote_45" class="fnanchor">45</a> Nor were Kircher’s anticipations random

-guesses, but the result of deductions from experiment and observation;

-and the universality of magnetism is now almost

-recognised by philosophers.</p>

-

-<h3>MINUTE MEASUREMENT OF TIME.</h3>

-

-<p>By observing the magnet in the highly-convenient and delicate

-manner introduced by Gauss and Weber, which consists<span class="pagenum"><a name="Page_195" id="Page_195">195</a></span>

-in attaching a mirror to the magnet and determining the constant

-factor necessary to convert the differences of oscillation

-into differences of time, Professor Helmholtz has been able,

-with comparatively simple apparatus, to make accurate determinations

-up to the 1/10000th part of a second.</p>

-

-<h3>POWER OF A MAGNET.</h3>

-

-<p>The Power of a Magnet is estimated by the weight its poles

-are able to carry. Each pole singly is able to support a smaller

-weight than when they both act together by means of a keeper,

-for which reason horse-shoe magnets are superior to bar magnets

-of similar dimensions and character. It has further been

-ascertained that small magnets have a much greater relative

-force than large ones.</p>

-

-<p>When magnetism is excited in a piece of steel in the ordinary

-mode, by friction with a magnet, it would seem that its

-inductive power is able to overcome the coercive power of the

-steel only to a certain depth below the surface; hence we see

-why small pieces of steel, especially if not very hard, are able

-to carry greater relative weights than large magnets. Sir Isaac

-Newton wore in a ring a magnet weighing only 3 grains, which

-would lift 760 grains, <i>i. e.</i> 250 times its own weight.</p>

-

-<p>Bar-magnets are seldom found capable of carrying more

-than their own weight; but horse-shoe magnets of similar steel

-will bear considerably more. Small ones of from half an ounce

-to 1 ounce in weight will carry from 30 to 40 times their own

-weight; while such as weigh from 1 to 2 lbs. will rarely carry

-more than from 10 to 15 times their weight. The writer found

-a 1 lb. horse-shoe magnet that he impregnated by means of the

-feeder able to bear 26½ times its own weight; and Fischer, having

-adopted the like mode of magnetising the steel, which he

-also carefully heated, has made magnets of from 1 to 3 lbs.

-weight that would carry 30 times, and others of from 4 to 6 lbs.

-weight that would carry 20 times, their own weight.&mdash;<i>Professor

-Peschel.</i></p>

-

-<h3>HOW ARTIFICIAL MAGNETS ARE MADE.</h3>

-

-<p>In 1750, Mr. Canton, F.R.S., “one of the most successful

-experimenters in the golden age of electricity,”<a name="FNanchor_46" id="FNanchor_46" href="#Footnote_46" class="fnanchor">46</a> communicated

-to the Royal Society his “Method of making Artificial Magnets

-without the use of natural ones.” This he effected by

-using a poker and tongs to communicate magnetism to steel

-bars. He derived his first hint from observing them one evening,

-as he was sitting by the fire, to be nearly in the same direction

-with the earth as the dipping needle. He thence concluded

-that they must, from their position and the frequent<span class="pagenum"><a name="Page_196" id="Page_196">196</a></span>

-blows they receive, have acquired some magnetic virtue, which

-on trial he found to be the case; and therefore he employed

-them to impregnate his bars, instead of having recourse to the

-natural loadstone. Upon the reading of the above paper, Canton

-exhibited to the Royal Society his experiments, for which

-the Copley Medal was awarded to him in 1751.</p>

-

-<p>Canton had, as early as 1747, turned his attention, with

-complete success, to the production of powerful artificial magnets,

-principally in consequence of the expense of procuring

-those made by Dr. Gowan Knight, who kept his process secret.

-Canton for several years abstained from communicating his

-method even to his most intimate friends, lest it might be

-injurious to Dr. Knight, who procured considerable pecuniary

-advantages by touching needles for the mariner’s compass.</p>

-

-<p>At length Dr. Knight’s method of making artificial magnets

-was communicated to the world by Mr. Wilson, in a paper

-published in the 69th volume of the <i>Philosophical Transactions</i>.

-He provided himself with a large quantity of clean iron-filings,

-which he put into a capacious tub about half full of clear

-water; he then agitated the tub to and fro for several hours,

-until the filings were reduced by attrition to an almost impalpable

-powder. This powder was then dried, and formed

-into paste by admixture with linseed-oil. The paste was then

-moulded into convenient shapes, which were exposed to a moderate

-heat until they had attained a sufficient degree of hardness.</p>

-

-<blockquote>

-

-<p>After allowing them to remain for some time in this state, Dr.

-Knight gave them their magnetic virtue in any direction he pleased,

-by placing them between the extreme ends of his large magazine of

-artificial magnets for a second or more, as he saw occasion. By this

-method the virtue they acquired was such, that when any one of these

-pieces was held between two of his best ten-guinea bars, with its poles

-purposely inverted, it immediately of itself turned about to recover its

-natural direction, which the force of those very powerful bars was not

-sufficient to counteract.</p></blockquote>

-

-<p>Dr. Knight’s powerful battery of magnets above mentioned

-is in the possession of the Royal Society, having been presented

-by Dr. John Fothergill in 1776.</p>

-

-<h3>POWER OF THE SUN’S RAYS IN INCREASING THE STRENGTH

-OF MAGNETS.</h3>

-

-<p>Professor Barlocci found that an armed natural loadstone,

-which would carry 1½ Roman pounds, had its power nearly

-<i>doubled</i> by twenty-four hours’ exposure to the strong light of

-the sun. M. Zantedeschi found that an artificial horse-shoe

-loadstone, which carried 13½ oz., carried 3½ more by three days’

-exposure, and at last arrived to 31 oz. by continuing it in the

-sun’s light. He found that while the strength increased in<span class="pagenum"><a name="Page_197" id="Page_197">197</a></span>

-oxidated magnets, it diminished in those which were not oxidated,

-the diminution becoming insensible when the loadstone

-was highly polished. He now concentrated the solar rays upon

-the loadstone by means of a lens; and he found that, both in

-oxidated and polished magnets, they <i>acquire</i> strength when

-their <i>north</i> pole is exposed to the sun’s rays, and <i>lose</i> strength

-when the <i>south</i> pole is exposed.&mdash;<i>Sir David Brewster.</i></p>

-

-<h3>COLOUR OF A BODY AND ITS MAGNETIC PROPERTIES.</h3>

-

-<p>Solar rays bleach dead vegetable matter with rapidity, while

-in living parts of plants their action is frequently to strengthen

-the colour. Their power is perhaps best seen on the sides of

-peaches, apples, &amp;c., which, exposed to a midsummer’s sun,

-become highly coloured. In the open winter of 1850, Mr. Adie,

-of Liverpool, found in a wallflower plant proof of a like effect:

-in the dark months there was a slow succession of one or two

-flowers, of uniform pale yellow hue; in March streaks of a

-darker colour appeared on the flowers, and continued to slowly

-increase till in April they were variegated brown and yellow,

-of rich strong colours. On the supposition that these changes

-are referable to magnetic properties, may hereafter be explained

-Mrs. Somerville’s experiments on steel needles exposed to the

-sun’s rays under envelopes of silk of various colours; the magnetisation

-of steel needles has failed in the coloured rays of the

-spectrum, but Mr. Adie considers that under dyed silk the effect

-will hinge on the chemical change wrought in the silk and

-its dye by the solar rays.</p>

-

-<h3>THE ONION AND MAGNETISM.</h3>

-

-<p>A popular notion has long been current, more especially on

-the shores of the Mediterranean, that if a magnetic rod be

-rubbed with an onion, or brought in contact with the emanations

-of the plant, the directive force will be diminished, while

-a compass thus treated will mislead the steersman. It is difficult

-to conceive what could have given rise to so singular a

-popular error.<a name="FNanchor_47" id="FNanchor_47" href="#Footnote_47" class="fnanchor">47</a>&mdash;<i>Humboldt’s Cosmos</i>, vol. v.</p>

-

-<h3>DECLINATION OF THE NEEDLE&mdash;THE EARTH A MAGNET.</h3>

-

-<p>The Inclination or Dip of the Needle was first recorded by

-Robert Norman, in a scarce book published in 1576 entitled <i>The

-New Attractive; containing a short Discourse of the Magnet or

-Loadstone, &amp;c.</i></p>

-

-<p>Columbus has not only the merit of being the first to discover

-<i>a line without magnetic variation</i>, but also of having first<span class="pagenum"><a name="Page_198" id="Page_198">198</a></span>

-excited a taste for the study of terrestrial magnetism in Europe,

-by means of his observations on the progressive increase of

-western declination in receding from that line.</p>

-

-<p>The first chart showing the variation of the compass,<a name="FNanchor_48" id="FNanchor_48" href="#Footnote_48" class="fnanchor">48</a> or

-the declination of the needle, based on the idea of employing

-curves drawn through points of equal declination, is due to

-Halley, who is justly entitled the father and founder of terrestrial

-magnetism. And it is curious to find that in No. 195 of

-the <i>Philosophical Transactions</i>, in 1683, Halley had previously

-expressed his belief that he has put it past doubt that the

-globe of the earth is one great magnet, having four magnetical

-poles or points of attraction, near each pole of the equator two;

-and that in those parts of the world which lie near adjacent to

-any one of those magnetical poles, the needle is chiefly governed

-thereby, the nearest pole being always predominant

-over the more remote.</p>

-

-<p>“To Halley” (says Sir John Herschel) “we owe the first appreciation

-of the real complexity of the subject of magnetism.

-It is wonderful indeed, and a striking proof of the penetration

-and sagacity of this extraordinary man, that with his means of

-information he should have been able to draw such conclusions,

-and to take so large and comprehensive a view of the subject

-as he appears to have done.”</p>

-

-<p>And, in our time, “the earth is a great magnet,” says

-Faraday: “its power, according to Gauss, being equal to that

-which would be conferred if every cubic yard of it contained

-six one-pound magnets; the sum of the force is therefore equal

-to 8,464,000,000,000,000,000,000 such magnets.”</p>

-

-<h3>THE AURORA BOREALIS.</h3>

-

-<p>Halley, upon his return from his voyage to verify his theory

-of the variation of the compass, in 1700, hazarded the conjecture

-that the Aurora Borealis is a magnetic phenomenon. And

-Faraday’s brilliant discovery of the evolution of light by magnetism

-has raised Halley’s hypothesis, enounced in 1714, to

-the rank of an experimental certainty.</p>

-

-<h3>EFFECT OF LIGHT ON THE MAGNET.</h3>

-

-<p>In 1854, Sir John Ross stated to the British Association, in

-proof of the effect of every description of light on the magnet,

-that during his last voyage in the <i>Felix</i>, when frozen in about

-one hundred miles north of the magnetic pole, he concentrated<span class="pagenum"><a name="Page_199" id="Page_199">199</a></span>

-the rays of the full moon on the magnetic needle, when he found

-it was five degrees attracted by it.</p>

-

-<h3>MAGNETO-ELECTRICITY.</h3>

-

-<p>In 1820, the Copley Medal was adjudicated to M. Oersted

-of Copenhagen, “when,” says Dr. Whewell, “the philosopher

-announced that the conducting-wire of a voltaic circuit acts

-upon a magnetic needle; and thus recalled into activity that

-endeavour to connect magnetism with electricity which, though

-apparently on many accounts so hopeful, had hitherto been attended

-with no success. Oersted found that the needle has a

-tendency to place itself at <i>right angles</i> to the wire; a kind of

-action altogether different from any which had been suspected.”</p>

-

-<h3>ELECTRO-MAGNETS OF THE HORSE-SHOE FORM</h3>

-

-<p class="in0">were discovered by Sturgeon in 1825. Of two Magnets made by

-a process devised by M. Elias, and manufactured by M. Logemeur

-at Haerlem, one, a single horse-shoe magnet weighing

-about 1 lb., lifts 28½ lbs.; the other, a triple horse-shoe magnet

-of about 10 lbs. weight, is capable of lifting about 150 lbs. Similar

-magnets are made by the same person capable of supporting

-5 cwt. In the process of making them, a helix of

-copper and a galvanic battery are used. The smaller magnet

-has twice the power expressed by Haecker’s formula for the

-best artificial steel magnet.</p>

-

-<p>Subsequently Henry and Ten Eyk, in America, constructed

-some electro-magnets on a large scale. One horse-shoe magnet

-made by them, weighing 60 lbs., would support more than

-2000 lbs.</p>

-

-<p>In September 1858, there were constructed for the Atlantic-telegraph

-cable at Valentia two permanent magnets, from

-which the electric induction is obtained: each is composed of

-30 horse-shoe magnets, 2½ feet long and from 4 to 5 inches

-broad; the induction coils attached to these each contain six

-miles of wire, and a shock from them, if passed through the

-human body, would be sufficient to destroy life.</p>

-

-<h3>ROTATION-MAGNETISM.</h3>

-

-<p>The unexpected discovery of Rotation-Magnetism by Arago,

-in 1825, has shown practically that every kind of matter is susceptible

-of magnetism; and the recent investigations of Faraday

-on diamagnetic substances have, under special conditions

-of meridian or equatorial direction, and of solid, fluid, or gaseous

-inactive conditions of the bodies, confirmed this important result.</p>

-

-<p><span class="pagenum"><a name="Page_200" id="Page_200">200</a></span></p>

-

-<h3>INFLUENCE OF PENDULUMS ON EACH OTHER.</h3>

-

-<p>About a century since it became known, that when two

-clocks are in action upon the same shelf, they will disturb each

-other: that the pendulum of the one will stop that of the other;

-and that the pendulum that was stopped will after a while resume

-its vibrations, and in its turn stop that of the other clock.

-When two clocks are placed near one another in cases very

-slightly fixed, or when they stand on the boards of a floor, they

-will affect a little each other’s pendulum. Mr. Ellicote observed

-that two clocks resting against the same rail, which agreed to a

-second for several days, varied one minute thirty-six seconds in

-twenty-four hours when separated. The slower, having a longer

-pendulum, set the other in motion in 16-1/3 minutes, and stopped

-itself in 36-2/3 minutes.</p>

-

-<h3>WEIGHT OF THE EARTH ASCERTAINED BY THE PENDULUM.</h3>

-

-<p>By a series of comparisons with Pendulums placed at the

-surface and the interior of the Earth, the Astronomer-Royal has

-ascertained the variation of gravity in descending to the bottom

-of a deep mine, as the Harton coal-pit, near South Shields. By

-calculations from these experiments, he has found the mean

-density of the earth to be 6·566, the specific gravity of water

-being represented by unity. In other words, it has been ascertained

-by these experiments that if the earth’s mass possessed

-every where its average density, it would weigh, bulk for bulk,

-6·566 times as much as water. It is curious to note the different

-values of the earth’s mean density which have been

-obtained by different methods. The Schehallien experiment

-indicated a mean density equal to about 4½; the Cavendish

-apparatus, repeated by Baily and Reich, about 5½; and Professor

-Airy’s pendulum experiment furnishes a value amounting

-to about 6½.</p>

-

-<p>The immediate result of the computations of the Astronomer-Royal

-is: supposing a clock adjusted to go true time at

-the top of the mine, it would gain 2¼ seconds per day at the

-bottom. Or it may be stated thus: that gravity is greater at

-the bottom of a mine than at the top by 1/19190th part.&mdash;<i>Letter to

-James Mather, Esq., South Shields.</i> See also <i>Professor Airy’s Lecture</i>,

-1854.</p>

-

-<h3>ORIGIN OF TERRESTRIAL MAGNETISM.</h3>

-

-<p>The earliest view of Terrestrial Magnetism supposed the existence

-of a magnet at the earth’s centre. As this does not accord

-with the observations on declination, inclination, and intensity,

-Tobias Meyer gave this fictitious magnet an eccentric

-position, placing it one-seventh part of the earth’s radius from

-the centre. Hansteen imagined that there were two such magnets,<span class="pagenum"><a name="Page_201" id="Page_201">201</a></span>

-different in position and intensity. Ampère set aside these

-unsatisfactory hypotheses by the view, derived from his discovery,

-that the earth itself is an electro-magnet, magnetised by an

-electric current circulating about it from east to west perpendicularly

-to the plane of the magnetic meridian, to which the

-same currents give direction as well as magnetise the ores of

-iron: the currents being thermo-electric currents, excited by the

-action of the sun’s heat successively on the different parts of the

-earth’s surface as it revolves towards the east.</p>

-

-<p>William Gilbert,<a name="FNanchor_49" id="FNanchor_49" href="#Footnote_49" class="fnanchor">49</a> who wrote an able work on magnetic and

-electric forces in the year 1600, regarded terrestrial magnetism

-and electricity as two emanations of a single fundamental source

-pervading all matter, and he therefore treated of both at once.

-According to Gilbert’s idea, the earth itself is a magnet; whilst

-he considered that the inflections of the lines of equal declination

-and inclination depend upon the distribution of mass, the

-configuration of continents, or the form and extent of the deep

-intervening oceanic basins.</p>

-

-<p>Till within the last eighty years, it appears to have been the

-received opinion that the intensity of terrestrial magnetism was

-the same at all parts of the earth’s surface. In the instructions

-drawn up by the French Academy for the expedition under La

-Pérouse, the first intimation is given of a contrary opinion. It

-is recommended that the time of vibration of a dipping-needle

-should be observed at stations widely remote, as a test of the

-equality or difference of the magnetic intensity; suggesting also

-that such observations should particularly be made at those parts

-of the earth where the dip was greatest and where it was least.

-The experiments, whatever their results may have been, which,

-in compliance with this recommendation, were made in the expedition

-of La Pérouse, perished in its general catastrophe; but

-the instructions survived.</p>

-

-<p>In 1811, Hansteen took up the subject, and in 1819 published

-his celebrated work, clearly demonstrating the fluctuations

-which this element has undergone during the last two

-centuries; confirming in great detail the position of Halley,

-that “the whole magnetic system is in motion, that the moving

-force is very great as extending its effects from pole to pole,

-and that its motion is not <i>per saltum</i>, but a gradual and regular

-motion.”</p>

-

-<h3>THE NORTH AND SOUTH MAGNETIC POLES.</h3>

-

-<p>The knowledge of the geographical position of both Magnetic

-Poles is due to the scientific energy of the same navigator,<span class="pagenum"><a name="Page_202" id="Page_202">202</a></span>

-Sir James Ross. His observations of the Northern Magnetic

-Pole were made during the second expedition of his uncle,

-Sir John Ross (1829&ndash;1833); and of the Southern during the

-Antarctic expedition under his own command (1839&ndash;1843). The

-Northern Magnetic Pole, in 70° 5′ lat., 96° 43′ W. long., is 5° of

-latitude farther from the ordinary pole of the earth than the

-Southern Magnetic Pole, 75° 35′ lat., 154° 10′ E. long.; whilst

-it is also situated farther west from Greenwich than the Northern

-Magnetic Pole. The latter belongs to the great island of

-Boothia Felix, which is situated very near the American continent,

-and is a portion of the district which Captain Parry had

-previously named North Somerset. It is not far distant from

-the western coast of Boothia Felix, near the promontory of Adelaide,

-which extends into King William’s Sound and Victoria

-Strait.</p>

-

-<p>The Southern Magnetic Pole has been directly reached in

-the same manner as the Northern Pole. On 17th February

-1841, the <i>Erebus</i> penetrated as far as 76° 12′ S. lat., and 164°

-E. long. As the inclination was here only 88° 40′, it was assumed

-that the Southern Magnetic Pole was about 160 nautical miles

-distant. Many accurate observations of declination, determining

-the intersection of the magnetic meridian, render it very

-probable that the South Magnetic Pole is situated in the interior

-of the great Antarctic region of South Victoria Land, west

-of the Prince Albert mountains, which approach the South Pole

-and are connected with the active volcano of Erebus, which is

-12,400 feet in height.&mdash;<i>Humboldt’s Cosmos</i>, vol. v.</p>

-

-<h3>MAGNETIC STORMS.</h3>

-

-<p>The mysterious course of the magnetic needle is equally affected

-by time and space, by the sun’s course, and by changes

-of place on the earth’s surface. Between the tropics the hour

-of the day may be known by the direction of the needle as well

-as by the oscillations of the barometer. It is affected instantly,

-but transiently, by the northern light.</p>

-

-<p>When the uniform horary motion of the needle is disturbed

-by a magnetic storm, the perturbation manifests itself <i>simultaneously</i>,

-in the strictest sense of the word, over hundreds and

-thousands of miles of sea and land, or propagates itself by degrees

-in short intervals every where over the earth’s surface.</p>

-

-<p>Among numerous examples of perturbations occurring simultaneously

-and extending over wide portions of the earth’s surface,

-one of the most remarkable is that of September 25th, 1841,

-which was observed at Toronto in Canada, at the Cape of Good

-Hope, at Prague, and partially in Van Diemen’s Land. Sabine

-adds, “The English Sunday, on which it is deemed sinful,

-after midnight on Saturday, to register an observation, and<span class="pagenum"><a name="Page_203" id="Page_203">203</a></span>

-to follow out the great phenomena of creation in their perfect

-development, interrupted the observation in Van Diemen’s Land,

-where, in consequence of the difference of the longitude, the

-magnetic storm fell on Sunday.”</p>

-

-<blockquote>

-

-<p>It is but justice to add, that to the direct instrumentality of the British

-Association we are indebted for this system of observation, which

-would not have been possible without some such machinery for concerted

-action. It being known that the magnetic needle is subject to oscillations,

-the nature, the periods, and the laws of which were unascertained,

-under the direction of a committee of the Association <i>magnetic observatories</i>

-were established in various places for investigating these strange

-disturbances. As might have been anticipated, regularly recurring perturbations

-were noted, depending on the hour of the day and the season

-of the year. Magnetic storms were observed to sweep simultaneously over

-the whole face of the earth, and these too have now been ascertained to

-follow certain periodic laws.</p>

-

-<p>But the most startling result of the combined magnetic observations

-is the discovery of marked perturbations recurring at intervals of ten

-years; a period which seemed to have no analogy to any thing in the

-universe, but which M. Schwabe has found to correspond with the variation

-of the spots on the sun, both attaining their maximum and minimum

-developments at the same time. Here, for the present, the discovery

-stops; but that which is now an unexplained coincidence may

-hereafter supply the key to the nature and source of Terrestrial Magnetism:

-or, as Dr. Lloyd observes, this system of magnetic observation

-has gone beyond our globe, and opened a new range for inquiry, by

-showing us that this wondrous agent has power in other parts of the

-solar system.</p></blockquote>

-

-<h3>FAMILIAR GALVANIC EFFECTS.</h3>

-

-<p>By means of the galvanic agency a variety of surprising

-effects have been produced. Gunpowder, cotton, and other inflammable

-substances have been set on fire; charcoal has been

-made to burn with a brilliant white flame; water has been decomposed

-into its elementary parts; metals have been melted

-and set on fire; fragments of diamond, charcoal, and plumbago

-have been dispersed as if evaporated; platina, the hardest and

-the heaviest of the metals, has been melted as readily as wax

-in the flame of a candle; the sapphire, quartz, magnesia, lime,

-and the firmest compounds in nature, have been fused. Its

-effects on the animal system are no less surprising.</p>

-

-<p>The agency of galvanism explains why porter has a different

-and more pleasant taste when drunk out of a pewter-pot than

-out of glass or earthenware; why works of metal which are

-soldered together soon tarnish in the place where the metals are

-joined; and why the copper sheathing of ships, when fastened

-with iron nails, is soon corroded about the place of contact. In

-all these cases a galvanic circle is formed which produces the

-effects.</p>

-

-<h3>THE SIAMESE TWINS GALVANISED.</h3>

-

-<p>It will be recollected that the Siamese twins, brought to<span class="pagenum"><a name="Page_204" id="Page_204">204</a></span>

-England in the year 1829, were united by a jointed cartilaginous

-band. A silver tea spoon being placed on the tongue of

-one of the twins and a disc of zinc on the tongue of the other,

-the moment the two metals were brought into contact both

-the boys exclaimed, “Sour, sour;” thus proving that the galvanic

-influence passed from the one to the other through the

-connecting band.</p>

-

-<h3>MINUTE AND VAST BATTERIES.</h3>

-

-<p>Dr. Wollaston made a simple apparatus out of a silver thimble,

-with its top cut off. It was then partially flattened, and

-a small plate of zinc being introduced into it, the apparatus was

-immersed in a weak solution of sulphuric acid. With this minute

-battery, Dr. Wollaston was able to fuse a wire of platinum

-1/3000th of an inch in diameter&mdash;a degree of tenuity to which no

-one had ever succeeded in drawing it.</p>

-

-<p>Upon the same principle (that of introducing a plate of zinc

-between two plates of other metals) Mr. Children constructed

-his immense battery, the zinc plates of which measured six feet

-by two feet eight inches; each plate of zinc being placed between

-two of copper, and each triad of plates being enclosed in

-a separate cell. With this powerful apparatus a wire of platinum,

-1/10th of an inch in diameter and upwards of five feet long,

-was raised to a red heat, visible even in the broad glare of daylight.</p>

-

-<p>The great battery at the Royal Institution, with which Sir

-Humphry Davy discovered the composition of the fixed alkalies,

-was of immense power. It consisted of 200 separate parts, each

-composed of ten double plates, and each plate containing thirty-two

-square inches; the number of double plates being 2000, and

-the whole surface 128,000 square inches.</p>

-

-<p>Mr. Highton, C.E., has made a battery which exposes a surface

-of only 1/100th part of an inch: it consists of but one cell; it

-is less than 1/10000th part of a cubic inch, and yet it produces

-electricity more than enough to overcome all the resistance in

-the inventor’s brother’s patent Gold-leaf Telegraph, and works

-the same powerfully. It is, in short, a battery which, although

-<i>it will go through the eye of a needle</i>, will yet work a telegraph

-well. Mr. Highton had previously constructed a battery in size

-less than 1/40th of a cubic inch: this battery, he found, would

-for a month together ring a telegraph-bell ten miles off.</p>

-

-<h3>ELECTRIC INCANDESCENCE OF CHARCOAL POINTS.</h3>

-

-<p>The most splendid phenomenon of this kind is the combustion

-of charcoal points. Pointed pieces of the residuum obtained

-from gas retorts will answer best, or Bunsen’s composition

-may be used for this purpose. Put two such charcoal<span class="pagenum"><a name="Page_205" id="Page_205">205</a></span>

-points in immediate contact with the wires of your battery;

-bring the points together, and they will begin to burn with a

-dazzling white light. The charcoal points of the large apparatus

-belonging to the Royal Institution became incandescent at

-a distance of 1/30th of an inch; when the distance was gradually

-increased till they were four inches asunder, they continued to

-burn with great intensity, and a permanent stream of light

-played between them. Professor Bunsen obtained a similar

-flame from a battery of four pairs of plates, its carbon surface

-containing 29 feet. The heat of this flame is so intense, that

-stout platinum wire, sapphire, quartz, talc, and lime are reduced

-by it to the liquid form. It is worthy of remark, that no

-combustion, properly so called, takes place in the charcoal itself,

-which sustains only an extremely minute loss in its weight

-and becomes rather denser at the points. The phenomenon is

-attended with a still more vivid brightness if the charcoal points

-are placed in a vacuum, or in any of those gases which are not

-supporters of combustion. Instead of two charcoal points, one

-only need be used if the following arrangement is adopted: lay

-the piece of charcoal on some quicksilver that is connected with

-one pole of the battery, and complete the circuit from the other

-pole by means of a strip of platinum. When Professor Peschel

-used a piece of well-burnt coke in the manner just described,

-he obtained a light which was almost intolerable to the eyes.</p>

-

-<h3>VOLTAIC ELECTRICITY.</h3>

-

-<p>On January 31, 1793, Volta announced to the Royal Society

-his discovery of the development of electricity in metallic bodies.

-Galvani had given the name of Animal Electricity to the power

-which caused spontaneous convulsions in the limbs of frogs

-when the divided nerves were connected by a metallic wire.

-Volta, however, saw the true cause of the phenomena described

-by Galvani. Observing that the effects were far greater when

-the connecting medium consisted of two different kinds of

-metal, he inferred that the principle of excitation existed in

-the metals, and not in the nerves of the animal; and he assumed

-that the exciting fluid was ordinary electricity, produced

-by the contact of the two metals; the convulsions of the frog

-consequently arose from the electricity thus developed passing

-along its nerves and muscles.</p>

-

-<p>In 1800 Volta invented what is now called the Voltaic

-Pile, or compound Galvanic circle.</p>

-

-<blockquote>

-

-<p>The term Animal Electricity (says Dr. Whewell) has been superseded

-by others, of which <i>Galvanism</i> is the most familiar; but I think that

-Volta’s office in this discovery is of a much higher and more philosophical

-kind than that of Galvani; and it would on this account be more fitting

-to employ the term <i>Voltaic Electricity</i>, which, indeed, is very commonly<span class="pagenum"><a name="Page_206" id="Page_206">206</a></span>

-used, especially by our most recent and comprehensive writers.

-The <i>Voltaic pile</i> was a more important step in the history of electricity

-than the Leyden jar had been&mdash;<i>Hist. Ind. Sciences</i>, vol. iii.</p>

-

-<p>No one who wishes to judge impartially of the scientific history of

-these times and of its leaders, will consider Galvani and Volta as equals,

-or deny the vast superiority of the latter over all his opponents or fellow-workers,

-more especially over those of the Bologna school. We shall

-scarcely again find in one man gifts so rich and so calculated for research

-as were combined in Volta. He possessed that “incomprehensible

-talent,” as Dove has called it, for separating the essential from the immaterial

-in complicated phenomena; that boldness of invention which

-must precede experiment, controlled by the most strict and cautious

-mode of manipulation; that unremitting attention which allows no circumstance

-to pass unnoticed; lastly, with so much acuteness, so much

-simplicity, so much grandeur of conception, combined with such depth

-of thought, he had a hand which was the hand of a workman.&mdash;<i>Jameson’s

-Journal</i>, No. 106.</p></blockquote>

-

-<h3>THE VOLTAIC BATTERY AND THE GYMNOTUS.</h3>

-

-<p>“We boast of our Voltaic Batteries,” says Mr. Smee. “I

-should hardly be believed if I were to say that I did not feel

-pride in having constructed my own, especially when I consider

-the extensive operations which it has conducted. But when I

-compare my battery with the battery which nature has given

-to the electrical eel and the torpedo, how insignificant are human

-operations compared with those of the Architect of living

-beings! The stupendous electric eel in the Polytechnic Institution,

-when he seeks to kill his prey, encloses him in a circle;

-then, by volition, causes the voltaic force to be produced, and

-the hapless creature is instantly killed. It would probably require

-ten thousand of my artificial batteries to effect the same

-object, as the creature is killed <i>instanter</i> on receiving the shock.

-As much, however, as my battery is inferior to that of the electric

-fish, so is man superior to the same animal. Man is endowed

-with a power of mind competent to appreciate the force

-of matter, and is thus enabled to make the battery. The eel

-can but use the specific apparatus which nature has bestowed

-upon it.”</p>

-

-<p>Some observations upon the electric current around the

-gymnotus, and notes of experiments with this and other electric

-fish, will be found in <i>Things not generally Known</i>, p. 199.</p>

-

-<h3>VOLTAIC CURRENTS IN MINES.</h3>

-

-<p>Many years ago, Mr. R.&nbsp;W. Fox, from theory entertaining

-a belief that a connection existed between voltaic action in the

-interior of the earth and the arrangement of metalliferous veins,

-and also the progressive increase of temperature in the strata as

-we descend from the surface, endeavoured to verify the same

-from experiment in the mine of Huel Jewel, in Cornwall. His<span class="pagenum"><a name="Page_207" id="Page_207">207</a></span>

-apparatus consisted of small plates of sheet-copper, which were

-fixed in contact with a plate in the veins with copper nails, or

-else wedged closely against them with wooden props stretched

-across the galleries. Between two of these plates, at different

-stations, a communication was made by means of a copper

-wire 1/20th of an inch in diameter, which included a galvanometer

-in its circuit. In some instances 300 fathoms of copper wire

-were employed. It was then found that the intensity of the

-voltaic current was generally greater in proportion to the

-greater abundance of copper ore in the veins, and in some degree

-to the depth of the stations. Hence Mr. Fox’s discovery

-promised to be of practical utility to the miner in discovering

-the relative quantity of ore in the veins, and the directions in

-which it most abounds.</p>

-

-<p>The result of extended experiments, mostly made by Mr.

-Robert Hunt, has not, however, confirmed Mr. Fox’s views.

-It has been found that the voltaic currents detected in the lodes

-are due to the chemical decomposition going on there; and the

-more completely this process of decomposition is established,

-the more powerful are the voltaic currents. Meanwhile these

-have nothing whatever to do with the increase of temperature

-with depth. Recent observations, made in the deep mines of

-Cornwall under the direction of Mr. Fox, do not appear consistent

-with the law of thermic increase as formerly established,

-the shallow mines giving a higher ratio of increase than the

-deeper ones.</p>

-

-<h3>GERMS OF ELECTRIC KNOWLEDGE.</h3>

-

-<p>Two centuries and a half ago, Gilbert recognised that the

-property of attracting light substances when rubbed, be their

-nature what it may, is not peculiar to amber, which is a condensed

-earthy juice cast up by the waves of the sea, and in

-which flying insects, ants, and worms lie entombed as in eternal

-sepulchres. The force of attraction (Gilbert continues) belongs

-to a whole class of very different substances, as glass,

-sulphur, sealing-wax, and all resinous substances&mdash;rock crystal

-and all precious stones, alum and rock-salt. Gilbert measured

-the strength of the excited electricity by means of a small

-needle&mdash;not made of iron&mdash;which moved freely on a pivot, and

-perfectly similar to the apparatus used by Haüy and Brewster

-in testing the electricity excited in minerals by heat and friction.

-“Friction,” says Gilbert further, “is productive of a

-stronger effect in dry than in humid air; and rubbing with

-silk cloths is most advantageous.”</p>

-

-<p>Otto von Guerike, the inventor of the air-pump, was the

-first who observed any thing more than mere phenomena of

-attraction. In his experiments with a rubbed piece of sulphur<span class="pagenum"><a name="Page_208" id="Page_208">208</a></span>

-he recognised the phenomena of repulsion, which subsequently

-led to the establishment of the laws of the sphere of action and

-of the distribution of electricity. <i>He heard the first sound, and

-saw the first light, in artificially-produced electricity.</i> In an experiment

-instituted by Newton in 1675, the first traces of an

-electric charge in a rubbed plate of glass were seen.</p>

-

-<h3>TEMPERATURE AND ELECTRICITY.</h3>

-

-<p>Professor Tyndall has shown that all variations of temperature,

-in metals at least, excite electricity. When the wires of

-a galvanometer are brought in contact with the two ends of a

-heated poker, the prompt deflection of the galvanometer-needle

-indicates that a current of electricity has been sent through

-the instrument. Even the two ends of a spoon, one of which

-has been dipped in hot water, serve to develop an electric

-current; and in cutting a hot beefsteak with a steel knife and

-a silver fork there is an excitement of electricity. The mere

-heat of the finger is sufficient to cause the deflection of the

-galvanometer; and when ice is applied to the part that has

-been previously warmed, the galvanometer-needle is deflected

-in the contrary direction. A small instrument invented by

-Melloni is so extremely sensitive of the action of heat, that

-electricity is excited when the hand is held six inches from it.</p>

-

-<h3>VAST ARRANGEMENT OF ELECTRICITY.</h3>

-

-<p>Professor Faraday has shown that the Electricity which decomposes,

-and that which is evolved in the decomposition of,

-a certain quantity of matter, are alike. What an enormous

-quantity of electricity, therefore, is required for the decomposition

-of a single grain of water! It must be in quantity sufficient

-to sustain a platinum wire 1/104th of an inch in thickness

-red-hot in contact with the air for three minutes and three-quarters.

-It would appear that 800,000 charges of a Leyden

-battery, charged by thirty turns of a very large and powerful

-plate-machine in full action, are necessary to supply electricity

-sufficient to decompose a single grain of water, or to equal the

-quantity of electricity which is naturally associated with the

-elements of that grain of water, endowing them with their mutual

-chemical affinity. Now the above quantity of electricity,

-if passed at once through the head of a rat or a cat, would kill

-it as by a flash of lightning. The quantity is, indeed, equal to

-that which is developed from a charged thunder-cloud.</p>

-

-<h3>DECOMPOSITION OF WATER BY ELECTRICITY.</h3>

-

-<p>Professor Andrews, by an ingenious arrangement, is enabled

-to show that water is decomposed by the common machine;<span class="pagenum"><a name="Page_209" id="Page_209">209</a></span>

-and by using an electrical kite, he was able, in fine weather, to

-produce decomposition, although so slowly that only 1/700000th

-of a grain of water was decomposed per hour. Faraday has

-proved that the decomposition of one single grain of water produces

-more electricity than is contained in the most powerful

-flash of lightning.</p>

-

-<h3>ELECTRICITY IN BREWING.</h3>

-

-<p>Mr. Black, a practical writer upon Brewing, has found that

-by the practice of imbedding the fermentation-vats in the earth,

-and connecting them by means of metallic pipes, an electrical

-current passes through the beer and causes it to turn sour. As

-a preventive, he proposed to place the vats upon wooden blocks,

-or on any other non-conductors, so that they may be insulated.

-It has likewise been ascertained that several brewers who had

-brewed excellent ale on the south side of the street, on removing

-to the north have failed to produce good ale.</p>

-

-<h3>ELECTRIC PAPER.</h3>

-

-<p>Professor Schonbein has prepared paper, as transparent as

-glass and impermeable to water, which develops a very energetic

-electric force. By placing some sheets on each other,

-and simply rubbing them once or twice with the hand, it becomes

-difficult to separate them. If this experiment is performed

-in the dark, a great number of distinct flashes may be

-perceived between the separated surfaces. The disc of the

-electrophorus, placed on a sheet that has been rubbed, produces

-sparks of some inches in length. A thin and very dry

-sheet of paper, placed against the wall, will adhere strongly

-to it for several hours if the hand be passed only once over it.

-If the same sheet be passed between the thumb and fore-finger

-in the dark, a luminous band will be visible. Hence with this

-paper may be made powerful and cheap electrical machines.</p>

-

-<h3>DURATION OF THE ELECTRIC SPARK.</h3>

-

-<p>By means of Professor Wheatstone’s apparatus, the Duration

-of the Electric Spark has been ascertained not to exceed

-the twenty-five-thousandth part of a second. A cannon-ball,

-if illumined in its flight by a flash of lightning, would, in

-consequence of the momentary duration of the light, appear to

-be stationary, and even the wings of an insect, that move ten

-thousand times in a second, would seem at rest.</p>

-

-<h3>VELOCITY OF ELECTRIC LIGHT.</h3>

-

-<p>On comparing the velocities of solar, stellar, and terrestrial

-light, which are all equally refracted in the prism, with the<span class="pagenum"><a name="Page_210" id="Page_210">210</a></span>

-velocity of the light of frictional electricity, we are disposed,

-in accordance with Wheatstone’s ingeniously-conducted experiments,

-to regard the lowest ratio in which the latter excels the

-former as 3:2. According to the lowest results of Wheatstone’s

-apparatus, electric light traverses 288,000 miles in a second.

-If we reckon 189,938 miles for stellar light, according to Struve,

-we obtain the difference of 95,776 miles as the greater velocity

-of electricity in one second.</p>

-

-<p>From the experiment described in Wheatstone’s paper (<i>Philosophical

-Transactions</i> for 1834), it would appear that the human

-eye is capable of perceiving phenomena of light whose

-duration is limited to the millionth part of a second.</p>

-

-<p>In Professor Airy’s experiments with the electric telegraph

-to determine the difference of longitude between Greenwich

-and Brussels, the time spent by the electric current in passing

-from one observatory to the other (270 miles) was found to be

-0·109″ or rather more than <i>the ninth part of a second</i>; and

-this determination rests on 2616 observations: a speed which

-would “girdle the globe” in ten seconds.</p>

-

-<h3>IDENTITY OF ELECTRIC AND MAGNETIC ATTRACTION.</h3>

-

-<p>This vague presentiment of the ancients has been verified

-in our own times. “When electrum (amber),” says Pliny, “is

-animated by friction and heat, it will attract bark and dry

-leaves precisely as the loadstone attracts iron.” The same

-words may be found in the literature of an Asiatic nation, and

-occur in a eulogium on the loadstone by the Chinese physicist

-Knopho, in the fourth century: “The magnet attracts iron

-as amber does the smallest grain of mustard-seed. It is like a

-breath of wind, which mysteriously penetrates through both,

-and communicates itself with the rapidity of an arrow.”</p>

-

-<blockquote>

-

-<p>Humboldt observed with astonishment on the woody banks of the

-Orinoco, in the sports of the natives, that the excitement of electricity

-by friction was known to these savage races. Children may be seen to

-rub the dry, flat, and shining seeds or husks of a trailing plant until

-they are able to attract threads of cotton and pieces of bamboo-cane.

-What a chasm divides the electric pastime of these naked copper-coloured

-Indians from the discovery of a metallic conductor discharging

-its electric shocks, or a pile formed of many chemically-decomposing

-substances, or a light-engendering magnetic apparatus! In such a

-chasm lie buried thousands of years, that compose the history of the intellectual

-development of mankind.&mdash;<i>Humboldt’s Cosmos</i>, vol. i.</p></blockquote>

-

-<h3>THEORY OF THE ELECTRO-MAGNETIC ENGINE.</h3>

-

-<p>Several years ago a speculative American set the industrial

-world of Europe in excitement by this proposition. The Magneto-Electric

-Machines often made use of in the case of rheumatic

-disorders are well known. By imparting a swift rotation<span class="pagenum"><a name="Page_211" id="Page_211">211</a></span>

-to the magnet of such a machine, we obtain powerful currents

-of electricity. If these be conducted through water, the latter

-will be reduced to its two components, oxygen and hydrogen.

-By the combustion of hydrogen water is again generated. If

-this combustion takes place, not in atmospheric air, in which

-oxygen only constitutes a fifth part, but in pure oxygen, and

-if a bit of chalk be placed in the flame, the chalk will be raised

-to a white heat, and give us the sun-like Drummond light: at

-the same time the flame develops a considerable quantity of

-heat. Now the American inventor proposed to utilise in this

-way the gases obtained from electrolytic decomposition; and

-asserted that by the combustion a sufficient amount of heat

-was generated to keep a small steam-engine in action, which

-again drove his magneto-electric machine, decomposed the

-water, and thus continually prepared its own fuel. This would

-certainly have been the most splendid of all discoveries,&mdash;a perpetual

-motion which, besides the force that kept it going,

-generated light like the sun, and warmed all around it. The

-affair, however, failed, as was predicted by those acquainted

-with the physical investigations which bear upon the subject.&mdash;<i>Professor

-Helmholtz.</i></p>

-

-<h3>MAGNETIC CLOCK AND WATCH.</h3>

-

-<p>In the Museum of the Royal Society are two curiosities of

-the seventeenth century which are objects of much interest in

-association with the electric discoveries of our day. These are

-a Clock, described by the Count Malagatti (who accompanied

-Cosmo III., Grand Duke of Tuscany, to inspect the Museum

-in 1669) as more worthy of observation than all the other objects

-in the cabinet. Its “movements are derived from the

-vicinity of a loadstone, and it is so adjusted as to discover the

-distance of countries at sea by the longitude.” The analogy

-between this clock and the electric clock of the present day is

-very remarkable. Of kindred interest is “Hook’s Magnetic

-Watch,” often alluded to in the Royal Society’s Journal-book

-of 1669 as “going slower or faster according to the greater or

-less distance of the loadstone, and so moving regularly in any

-posture.”</p>

-

-<h3>WHEATSTONE’S ELECTRO-MAGNETIC CLOCK.</h3>

-

-<p>In this ingenious invention, the object of Professor Wheatstone

-was to enable a simple clock to indicate exactly the same

-time in as many different places, distant from each other, as

-may be required. A standard clock in an observatory, for example,

-would thus keep in order another clock in each apartment,

-and that too with such accuracy, that <i>all of them, however

-numerous, will beat dead seconds audibly with as great precision<span class="pagenum"><a name="Page_212" id="Page_212">212</a></span>

-as the standard astronomical time-piece with which they are

-connected</i>. But, besides this, the subordinate time-pieces thus

-regulated require none of the mechanism for maintaining or

-regulating the power. They consist simply of a face, with its

-second, minute, and hour hands, and a train of wheels which

-communicate motion from the action of the second-hand to

-that of the hour-hand, in the same manner as an ordinary clock-train.

-Nor is this invention confined to observatories and large

-establishments. The great horologe of St. Paul’s might, by a

-suitable network of wires, or even by the existing metallic

-pipes of the metropolis, be made to command and regulate all

-the other steeple-clocks in the city, and even every clock within

-the precincts of its metallic bounds. As railways and telegraphs

-extend from London nearly to the remotest cities and

-villages, the sensation of time may be transmitted along with

-the elements of language; and the great cerebellum of the

-metropolis may thus constrain by its sympathies, and regulate

-by its power, the whole nervous system of the empire.</p>

-

-<h3>HOW TO MAKE A COMMON CLOCK ELECTRIC.</h3>

-

-<p>M. Kammerer of Belgium effects this by an addition to any

-clock whereby it is brought into contact with the two poles of

-a galvanic battery, the wires from which communicate with a

-drum moved by the clockwork; and every fifteen seconds the

-current is changed, the positive and the negative being transmitted

-alternately. A wire is continued from the drum to the

-electric clock, the movement of which, through the plate-glass

-dial, is seen to be two pairs of small straight electro-magnets,

-each pair having their ends opposite to the other pair, with about

-half an inch space between. Within this space there hangs a

-vertical steel bar, suspended from a spindle at the top. The rod

-has two slight projections on each side parallel to the ends of

-the wire-coiled magnets. When the electric current comes on

-the wire from the positive end of the battery (through the

-drum of the regulator-clock) the positive magnets attract the

-bar to it, the distance being perhaps the sixteenth of an inch.

-When, at the end of fifteen seconds, the negative pole operates,

-repulsion takes effect, and the bar moves to the opposite side.

-This oscillating bar gives motion to a wheel which turns the

-minute and hour hands.</p>

-

-<p>M. Kammerer states, that if the galvanic battery be attached

-to any particular standard clock, any number of clocks,

-wherever placed, in a city or kingdom, and communicating with

-this by a wire, will indicate precisely the same time. Such is

-the precision, that the sounds of three clocks thus beating simultaneously

-have been mistaken as proceeding from one clock.</p>

-

-<p><span class="pagenum"><a name="Page_213" id="Page_213">213</a></span></p>

-

-<h3>DR. FRANKLIN’S ELECTRICAL KITE.</h3>

-

-<p>Several philosophers had observed that lightning and electricity

-possessed many common properties; and the light which

-accompanied the explosion, the crackling noise made by the

-flame, and other phenomena, made them suspect that lightning

-might be electricity in a highly powerful state. But this connection

-was merely the subject of conjecture until, in the year

-1750, Dr. Franklin suggested an experiment to determine the

-question. While he was waiting for the building of a spire at

-Philadelphia, to which he intended to attach his wire, the experiment

-was successfully made at Marly-la-Ville, in France, in

-the year 1752; when lightning was actually drawn from the

-clouds by means of a pointed wire, and it was proved to be

-really the electric fluid.</p>

-

-<blockquote>

-

-<p>Almost every early electrical discovery of importance was made by

-Fellows of the Royal Society, and is to be found recorded in the <i>Philosophical

-Transactions</i>. In the forty-fifth volume occurs the first mention

-of Dr. Franklin’s name, and his theory of positive and negative

-electricity. In 1756 he was elected into the Society, “without any fee

-or other payment.” His previous communications to the <i>Transactions</i>,

-particularly the account of his electrical kite, had excited great interest.

-(<i>Weld’s History of the Royal Society.</i>) It is thus described by him in a

-letter dated Philadelphia, October 1, 1752:</p>

-

-<p>“As frequent mention is made in the public papers from Europe of

-the success of the Marly-la-Ville experiment for drawing the electric fire

-from clouds by means of pointed rods of iron erected on high buildings,

-&amp;c., it may be agreeable to the curious to be informed that the same

-experiment has succeeded in Philadelphia, though made in a different

-and more easy manner, which any one may try, as follows:</p>

-

-<p>Make a small cross of two light strips of cedar, the arms so long as

-to reach to the four corners of a large thin silk handkerchief when extended.

-Tie the comers of the handkerchief to the extremities of the

-cross; so you have the body of a kite, which, being properly accommodated

-with a tail, loop, and string, will rise in the air like a kite made

-of paper; but this, being of silk, is fitter to bear the wet and wind of a

-thunder-gust without tearing. To the top of the upright stick of the

-cross is to be fixed a very sharp-pointed wire, rising a foot or more

-above the wood. To the end of the twine, next the band, is to be tied

-a silk ribbon; and where the twine and silk join a key may be fastened.</p>

-

-<p>The kite is to be raised when a thunder-gust appears to be coming

-on, and the person who holds the string must stand within a door or

-window, or under some cover, so that the silk ribbon may not be wet;

-and care must be taken that the twine does not touch the frame of the

-door or window. As soon as any of the thunder-clouds come over the

-kite, the pointed wire will draw the electric fire from them; and the

-kite, with all the twine, will be electrified; and the loose filaments of

-the twine will stand out every way, and be attracted by an approaching

-finger.</p>

-

-<p>When the rain has wet the kite and twine, so that it can conduct

-the electric fire freely, you will find it stream out plentifully from the

-key on the approach of your knuckle. At this key the phial may be

-charged; and from electric fire thus obtained spirits may be kindled,<span class="pagenum"><a name="Page_214" id="Page_214">214</a></span>

-and all the other electrical experiments be performed which are usually

-done by the help of a rubbed-glass globe or tube; and thus the sameness

-of the electric matter with that of lightning is completely demonstrated.”&mdash;<i>Philosophical

-Transactions.</i></p></blockquote>

-

-<p>Of all this great man’s (Franklin’s) scientific excellencies,

-the most remarkable is the smallness, the simplicity, the apparent

-inadequacy of the means which he employed in his

-experimental researches. His discoveries were all made with

-hardly any apparatus at all; and if at any time he had been

-led to employ instruments of a somewhat less ordinary description,

-he never rested satisfied until he had, as it were, afterwards

-translated the process by resolving the problem with

-such simple machinery that you might say he had done it

-wholly unaided by apparatus. The experiments by which the

-identity of lightning and electricity was demonstrated were

-made with a sheet of brown paper, a bit of twine or silk thread,

-and an iron key!&mdash;<i>Lord Brougham.</i><a name="FNanchor_50" id="FNanchor_50" href="#Footnote_50" class="fnanchor">50</a></p>

-

-<h3>FATAL EXPERIMENT WITH LIGHTNING.</h3>

-

-<p>These experiments are not without danger; and a flash of

-lightning has been found to be a very unmanageable instrument.

-In 1753, M. Richman, at St. Petersburg, was making an experiment

-of this kind by drawing lightning into his room, when,

-incautiously bringing his head too near the wire, he was struck

-dead by the flash, which issued from it like a globe of blue fire,

-accompanied by a dreadful explosion.</p>

-

-<h3>FARADAY’S ELECTRICAL ILLUSTRATIONS.</h3>

-

-<p>The following are selected from the very able series of lectures

-delivered by Professor Faraday at the Royal Institution:</p>

-

-<blockquote>

-

-<p><i>The Two Electricities.</i>&mdash;After having shown by various experiments

-the attractions and repulsions of light substances from excited glass and

-from an excited tube of gutta-percha, Professor Faraday proceeds to

-point out the difference in the character of the electricity produced by

-the friction of the two substances. The opposite characters of the electricity

-evolved by the friction of glass and of that excited by the friction

-of gutta-percha and shellac are exhibited by several experiments, in

-which the attraction of the positive and negative electricities to each

-other and the neutralisation of electrical action on the combination of

-the two forces are distinctly observable. Though adopting the terms

-“positive” and “negative” in distinguishing the electricity excited by

-glass from that excited by gutta-percha and resinous bodies, Professor

-Faraday is strongly opposed to the Franklinian theory from which these

-terms are derived. According to Franklin’s view of the nature of electrical

-excitement, it arises from the disturbance, by friction or other

-means, of the natural quantity of one electric fluid which is possessed

-by all bodies; an excited piece of glass having more than its natural<span class="pagenum"><a name="Page_215" id="Page_215">215</a></span>

-share, which has been taken from the rubber, the latter being consequently

-in a minus or negative state. This theory Professor Faraday

-considers to be opposed to the distinct characteristic actions of the two

-forces; and, in his opinion, it is impossible to deprive any body of electricity,

-and reduce it to the minus state of Franklin’s hypothesis.

-Taking a Zamboni’s pile, he applies its two ends separately to an electrometer,

-to show that each end produces opposite kinds of electricity,

-and that the zero, or absence of electrical excitement, only exists in the

-centre of the pile. To prove how completely the two electricities neutralise

-each other, an excited rod of gutta-percha and the piece of flannel

-with which it has been rubbed are laid on the top of the electrometer

-without any sign of electricity whilst they are together; but when either

-is removed, the gold leaves diverge with positive and negative electricity

-alternately. The Professor dwells strongly on the peculiarity of the

-dual force of electricity, which, in respect of its duality, is unlike any

-other force in nature. He then contrasts its phenomena of instantaneous

-conduction with those of the somewhat analogous force of heat;

-and he illustrates by several striking experiments the peculiar property

-which static electricity possesses of being spread only over the surfaces

-of bodies. A metal ice-pail is placed on an insulated stand and electrified,

-and a metal ball suspended by a string is introduced, and touches

-the bottom and sides without having any electricity imparted to it, but

-on touching the outside it becomes strongly electrical. The experiment

-is repeated with a wooden tub with the same result; and Professor Faraday

-mentions the still more remarkable manner in which he has

-proved the surface distribution of electricity by having a small chamber

-constructed and covered with tinfoil, which can be insulated; and whilst

-torrents of electricity are being evolved from the external surface, he

-enters it with a galvanometer, and cannot perceive the slightest manifestation

-of electricity within.</p>

-

-<p><i>The Two Threads.</i>&mdash;A curious experiment is made with two kinds of

-thread used as the conducting force. From the electric machine on the

-table a silk thread is first carried to the indicator a yard or two off, and

-is shown to be a non-conductor when the glass tube is rubbed and applied

-to the machine (although the silk, when wetted, conducted); while

-a metallic thread of the same thickness, when treated in the same way,

-conducts the force so much as to vehemently agitate the gold leaves

-within the indicator.</p>

-

-<p><i>Non-conducting Bodies.</i>&mdash;The action that occurs in bodies which

-cannot conduct is the most important part of electrical science. The

-principle is illustrated by the attraction and repulsion of an electrified

-ball of gilt paper by a glass tube, between which and the ball a sheet

-of shellac is suspended. The nearer a ball of another description&mdash;an

-unelectrical insulated body&mdash;is brought to the Leyden jar when charged,

-the greater influence it is seen to possess over the gold leaf within the

-indicator, by induction, not by conduction. The questions, how electricities

-attract each other, what kind of electricity is drawn from the

-machine to the hand, how the hand was electric, are thus illustrated.

-To show the divers operations of this wonderful force, a tub (a bad conductor)

-is placed by the electric machine. When the latter is charged,

-a ball, having been electrified from it, is held in the tub, and rattles

-against its sides and bottom. On the application of the ball to the indicator,

-the gold leaf is shown not to move, whereas it is agitated manifestly

-when the same process is gone through with the exception that

-the ball is made to touch the outside only of the tub. Similar experiments<span class="pagenum"><a name="Page_216" id="Page_216">216</a></span>

-with a ball in an ice-pail and a vessel of wire-gauze, into the

-latter of which is introduced a mouse, which is shown to receive no

-shock, and not to be frightened at all; while from the outside of the

-vessel electric sparks are rapidly produced. This latter demonstration

-proves that, as the mouse, so men and women, might be safe inside a

-building with proper conductors while lightning played about the exterior.

-The wire-gauze being turned inside out, the principle is shown

-to be irreversible in spite of the change&mdash;what has been the unelectrical

-inside of the vessel being now, when made the outside portion, capable

-of receiving and transmitting the power, while the original outside is

-now unelectrical.</p>

-

-<p><i>Repulsion of Bodies.</i>&mdash;A remarkable and playful experiment, by

-which the repulsion of bodies similarly electrified is illustrated, consists

-in placing a basket containing a heap of small pieces of paper on an insulated

-stand, and connecting it with the prime conductor of the electrical

-machine; when the pieces of paper rise rapidly after each other into

-the air, and descend on the lecture-table like a fall of snow. The effect

-is greatly increased when a metal disc is substituted for the basket.</p></blockquote>

-

-<h3>ORIGIN OF THE LEYDEN JAR.</h3>

-

-<p>Muschenbroek and Linnæus had made various experiments

-of a strong kind with water and wire. The former, as appears

-from a letter of his to Réaumur, filled a small bottle with water,

-and having corked it up, passed a wire through the cork into

-the bottle. Having rubbed the vessel on the outside and suspended

-it to the electric machine, he was surprised to find that

-on trying to pull the wire out he was subjected to an awfully

-severe shock in his joints and his whole body, such as he declared

-he would not suffer again for any experiment. Hence

-the Leyden jar, which owes its name to the University of Leyden,

-with which, we believe, Muschenbroek was connected.&mdash;<i>Faraday.</i></p>

-

-<h3>DANGER TO GUNPOWDER MAGAZINES.</h3>

-

-<p>By the illustration of a gas globule, which is ignited from a

-spark by induction, Mr. Faraday has proved in a most interesting

-manner that the corrugated-iron roofs of some gunpowder-magazines,&mdash;on

-the subject of which he had often been consulted

-by the builders, with a view to the greater safety of these manufactories,&mdash;are

-absolutely dangerous by the laws of induction;

-as, by the return of induction, while a storm was discharging

-itself a mile or two off, a secondary spark might ignite the building.</p>

-

-<h3>ARTIFICIAL CRYSTALS AND MINERALS.&mdash;“THE CROSSE MITE.”</h3>

-

-<p>Among the experimenters on Electricity in our time who

-have largely contributed to the “Curiosities of Science,” Andrew

-Crosse is entitled to special notice. In his school-days he

-became greatly attached to the study of electricity; and on settling<span class="pagenum"><a name="Page_217" id="Page_217">217</a></span>

-on his paternal estate, Fyne Court, on the Quantock Hills

-in Somersetshire, he there devoted himself to chemistry, mineralogy,

-and electricity, pursuing his experiments wholly independently

-of theories, and searching only for facts. In Holwell

-Cavern, near his residence, he observed the sides and the roof

-covered with Arragonite crystallisations, when his observations

-led him to conclude that the crystallisations were the effects,

-at least to some extent, of electricity. This induced him to

-make the attempt to form artificial crystals by the same means,

-which he began in 1807. He took some water from the cave,

-filled a tumbler, and exposed it to the action of a voltaic battery

-excited by water alone, letting the platinum-wires of the

-battery fall on opposite sides of the tumbler from the opposite

-poles of the battery. After ten days’ constant action, he produced

-crystals of carbonate of lime; and on repeating the experiment

-in the dark, he produced them in six days. Thus Mr.

-Crosse simulated in his laboratory one of the hitherto most mysterious

-processes of nature.</p>

-

-<p>He pursued this line of research for nearly thirty years at

-Fyne Court, where his electrical-room and laboratory were on

-an enormous scale: the apparatus had cost some thousands of

-pounds, and the house was nearly full of furnaces. He carried

-an insulated wire above the tops of the trees around his house

-to the length of a mile and a quarter, afterwards shortened to

-1800 feet. By this wire, which was brought into connection

-with the apparatus in a chamber, he was enabled to see continually

-the changes in the state of the atmosphere, and could

-use the fluid so collected for a variety of purposes. In 1816,

-at a meeting of country gentlemen, he prophesied that, “by

-means of electrical agency, we shall be able to communicate our

-thoughts simultaneously with the uttermost ends of the earth.”

-Still, though he foresaw the powers of the medium, he did not

-make any experiments in that direction, but confined himself

-to the endeavour to produce crystals of various kinds. He ultimately

-obtained forty-one mineral crystals, or minerals uncrystallised,

-in the form in which they are produced by nature, including

-one sub-sulphate of copper&mdash;an entirely new mineral,

-neither found in nature nor formed by art previously. His belief

-was that even diamonds might be produced in this way.</p>

-

-<p>Mr. Crosse worked alone in his retreat until 1836, when,

-attending the meeting of the British Association at Bristol,

-he was induced to explain his experiments, for which he was

-highly complimented by Dr. Buckland, Dr. Dalton, Professor

-Sedgwick, and others.<a name="FNanchor_51" id="FNanchor_51" href="#Footnote_51" class="fnanchor">51</a></p>

-

-<p><span class="pagenum"><a name="Page_218" id="Page_218">218</a></span>

-Shortly after Mr. Crosse’s return to Fyne Court, while pursuing

-his experiments for forming crystals from a highly caustic

-solution out of contact with atmospheric air, he was greatly

-surprised by the appearance of an insect. Black flint, burnt to

-redness and reduced to powder, was mixed with carbonate of

-potash, and exposed to a strong heat for fifteen minutes; and the

-mixture was poured into a black-lead crucible in an air furnace.

-It was reduced to powder while warm, mixed with boiling

-water, kept boiling for some minutes, and then hydrochloric

-acid was added to supersaturation. After being exposed to voltaic

-action for twenty-six days, a perfect insect of the Acari

-tribe made its appearance, and in the course of a few weeks

-about a hundred more. The experiment was repeated in other

-chemical fluids with the like results; and Mr. Weeks of Sandwich

-afterwards produced the Acari inferrocyanerret of potassium.

-The Acarus of Mr. Crosse was found to contribute a new

-species of that genus, nearly approaching the Acari found in

-cheese and flour, or more nearly, Hermann’s <i>Acarus dimidiatus</i>.</p>

-

-<p>This discovery occasioned great excitement. The possibility

-was denied, though Mr. Faraday is said to have stated in the

-same year that he had seen similar appearances in his own electrical

-experiments. Mr. Crosse was now accused of impiety and

-aiming at creation, to which attacks he thus replied:</p>

-

-<blockquote>

-

-<p>As to the appearance of the acari under long-continued electrical

-action, I have never in thought, word, or deed given any one a right

-to suppose that I considered them as a creation, or even as a formation,

-from inorganic matter. To create is to form a something out of a nothing.

-To annihilate is to reduce that something to a nothing. Both of

-these, of course, can only be the attributes of the Almighty. In fact, I

-can assure you most sacredly that I have never dreamed of any theory

-sufficient to account for their appearance. I confess that I was not a

-little surprised, and am so still, and quite as much as I was when the

-acari made their first appearance. Again, I have never claimed any

-merit as attached to these experiments. It was a matter of chance; I

-was looking for silicious formations, and animal matter appeared instead.</p></blockquote>

-

-<p>These Acari, if removed from their birthplace, lived and propagated;

-but uniformly died on the first recurrence of frost, and

-were entirely destroyed if they fell back into the fluid whence

-they arose.</p>

-

-<p>One of Mr. Crosse’s visitors thus describes the vast electrical

-room at Fyne Court:</p>

-

-<blockquote>

-

-<p>Here was an immense number of jars and gallipots, containing fluids

-on which electricity was operating for the production of crystals. But

-you are startled in the midst of your observations by the smart crackling

-sound that attends the passage of the electrical spark; you hear also<span class="pagenum"><a name="Page_219" id="Page_219">219</a></span>

-the rumbling of distant thunder. The rain is already plashing in great

-drops against the glass, and the sound of the passing sparks continues

-to startle your ear; you see at the window a huge brass conductor, with

-a discharging rod near it passing into the floor, and from the one knob to

-the other sparks are leaping with increasing rapidity and noise, every

-one of which would kill twenty men at one blow, if they were linked together

-hand in hand and the spark sent through the circle. From this

-conductor wires pass off without the window, and the electric fluid is

-conducted harmlessly away. Mr. Crosse approached the instrument as

-boldly as if the flowing stream of fire were a harmless spark. Armed

-with his insulated rod, he sent it into his batteries: having charged

-them, he showed how wire was melted, dissipated in a moment, by its

-passage; how metals&mdash;silver, gold, and tin&mdash;were inflamed and burnt

-like paper, only with most brilliant hues. He showed you a mimic aurora

-and a falling-star, and so proved to you the cause of those beautiful

-phenomena.</p></blockquote>

-

-<p>Mr. Crosse appears to have produced in all “about 200 varieties

-of minerals, exactly resembling in all respects similar ones

-found in nature.” He tried also a new plan of extracting gold

-from its ores by an electrical process, which succeeded, but was

-too expensive for common use. He was in the habit of saying

-that he could, like Archimedes, move the world “if he were

-able to construct a battery at once cheap, powerful, and durable.”

-His process of extracting metals from their ores has been

-patented. Among his other useful applications of electricity

-are the purifying by its means of brackish or sea-water, and the

-improving bad wine and brandy. He agreed with Mr. Quekett

-in thinking that it is by electrical action that silica and other

-mineral substances are carried into and assimilated by plants.

-Negative electricity Mr. Crosse found favourable to no plants

-except fungi; and positive electricity he ascertained to be injurious

-to fungi, but favourable to every thing else.</p>

-

-<p>Mr. Crosse died in 1855. His widow has published a very

-interesting volume of <i>Memorials</i> of the ingenious experimenter,

-from which we select the following:</p>

-

-<blockquote>

-

-<p>On one occasion Mr. Crosse kept a pair of soles under the electric

-action for three months; and at the end of that time they were sent to

-a friend, whose domestics knew nothing of the experiment. Before the

-cook dressed them, her master asked her whether she thought they were

-fresh, as he had some doubts. She replied that she was sure they were

-fresh; indeed, she said she could swear that they were alive yesterday!

-When served at table they appeared like ordinary fish; but when the

-family attempted to eat them, they were found to be perfectly tasteless&mdash;the

-electric action had taken away all the essential oil, leaving the

-fish unfit for food. However, the process is exceedingly useful for keeping

-fish, meat, &amp;c. fresh and <i>good</i> for ten days or a fortnight. I have

-never heard a satisfactory explanation of the cause of the antiseptic

-power communicated to water by the passage of the electric current.

-Whether ozone has not something to do with it, may be a question.

-The same effect is produced whichever two dissimilar metals are used.</p></blockquote>

-

-<hr />

-

-<p><span class="pagenum"><a name="Page_220" id="Page_220">220</a></span></p>

-

-<div class="chapter"></div>

-<h2><a name="Electric" id="Electric"></a>The Electric Telegraph.</h2>

-

-<h3>ANTICIPATIONS OF THE ELECTRIC TELEGRAPH.</h3>

-

-<p>The great secret of ubiquity, or at least of instantaneous transmission,

-has ever exercised the ingenuity of mankind in various

-romantic myths; and the discovery of certain properties of the

-loadstone gave a new direction to these fancies.</p>

-

-<p>The earliest anticipation of the Electric Telegraph of this

-purely fabulous character forms the subject of one of the <i>Prolusiones

-Academicæ</i> of the learned Italian Jesuit Strada, first

-published at Rome in the year 1617. Of this poem a free

-translation appeared in 1750. Strada’s fancy was this: “There

-is,” he supposes, “a species of loadstone which possesses such

-virtue, that if two needles be touched with it, and then balanced

-on separate pivots, and the one be turned in a particular

-direction, the other will sympathetically move parallel

-to it. He then directs each of these needles to be poised and

-mounted parallel on a dial having the letters of the alphabet

-arranged round it. Accordingly, if one person has one of the

-dials, and another the other, by a little pre-arrangement as to

-details a correspondence can be maintained between them at

-any distance by simply pointing the needles to the letters of

-the required words. Strada, in his poetical reverie, dreamt that

-some such sympathy might one day be found to hold up the

-Magnesian Stone.”</p>

-

-<p>Strada’s conceit seems to have made a profound impression

-on the master-minds of the day. His poem is quoted in many

-works of the seventeenth and eighteenth centuries; and Bishop

-Wilkins, in his book on Cryptology, is strangely afraid lest

-his readers should mistake Strada’s fancy for fact. Wilkins

-writes: “This invention is altogether imaginary, having no

-foundation in any real experiment. You may see it frequently

-confuted in those that treat concerning magnetical virtues.”</p>

-

-<p>Again, Addison, in the 241st No. of the <i>Spectator</i>, 1712,

-describes Strada’s “Chimerical correspondence,” and adds that,

-“if ever this invention should be revived or put in practice,”

-he “would propose that upon the lover’s dial-plate there

-should be written not only the four-and-twenty letters, but several

-entire words which have always a place in passionate epistles,

-as flames, darts, die, language, absence, Cupid, heart, eyes,

-being, drown, and the like. This would very much abridge the

-lover’s pains in this way of writing a letter, as it would enable<span class="pagenum"><a name="Page_221" id="Page_221">221</a></span>

-him to express the most useful and significant words with a

-single touch of the needle.”</p>

-

-<p>After Strada and his commentators comes Henry Van Etten,

-who shows how “Claude, being at Paris, and John at Rome,

-might converse together, if each had a needle touched by a

-stone of such virtue that as one moved itself at Paris the other

-should be moved at Rome:” he adds, “it is a fine invention,

-but I do not think there is a magnet in the world which has

-such virtue; besides, it is inexpedient, for treasons would be

-too frequent and too much protected. (<i>Recréations Mathématiques</i>:

-see 5th edition, Paris, 1660, p. 158.) Sir Thomas Browne

-refers to this “conceit” as “excellent, and, if the effect would

-follow, somewhat divine;” but he tried the two needles touched

-with the same loadstone, and placed in two circles of letters,

-“one friend keeping one and another the other, and agreeing

-upon an hour when they will communicate,” and found the tradition

-a failure that, “at what distance of place soever, when

-one needle shall be removed unto any letter, the other, by a

-wonderful sympathy, will move unto the same.” (See <i>Vulgar

-Errors</i>, book ii. ch. iii.)</p>

-

-<p>Glanvill’s <i>Vanity of Dogmatizing</i>, a work published in 1661,

-however, contains the most remarkable allusion to the prevailing

-telegraphic fancy. Glanvill was an enthusiast, and he clearly

-predicts the discovery and general adoption of the electric telegraph.

-“To confer,” he says, “at the distance of the Indies

-by sympathetic conveyance may be as usual to future times as

-to us in a literary correspondence.” By the word “sympathetic”

-he evidently intended to convey magnetic agency; for he

-subsequently treats of “conference at a distance by impregnated

-needles,” and describes the device substantially as it is

-given by Sir Thomas Browne, adding, that though it did not

-then answer, “by some other such way of magnetic efficiency

-it may hereafter with success be attempted, when magical history

-shall be enlarged by riper inspection; and ’tis not unlikely

-but that present discoveries might be improved to the performance.”

-This may be said to close the most speculative or mythical

-period in reference to the subject of electro-telegraphy.</p>

-

-<p>Electricians now began to be sedulous in their experiments

-upon the new force by friction, then the only known method

-of generating electricity. In 1729, Stephen Gray, a pensioner

-of the Charter-house, contrived a method of making electrical

-signals through a wire 765 feet long; yet this most important

-experiment did not excite much attention. Next Dr. Watson,

-of the Royal Society, experimented on the possibility of transmitting

-electricity through a large circuit from the simple fact of

-Le Monnier’s account of his feeling the stroke of the electrified

-fires through two of the basins of the Tuileries (which occupy<span class="pagenum"><a name="Page_222" id="Page_222">222</a></span>

-nearly an acre), by means of an iron chain lying upon the ground

-and stretched round half their circumference. In 1745, Dr. Watson,

-assisted by several members of the Royal Society, made a

-series of experiments to ascertain how far electricity could be

-conveyed by means of conductors. “They caused the shock to

-pass across the Thames at Westminster Bridge, the circuit being

-completed by making use of the river for one part of the chain

-of communication. One end of the wire communicated with

-the coating of a charged phial, the other being held by the observer,

-who in his other hand held an iron rod which he dipped

-into the river. On the opposite side of the river stood a gentleman,

-who likewise dipped an iron rod in the river with one

-hand, and in the other held a wire the extremity of which

-might be brought into contact with the wire of the phial. Upon

-making the discharge, the shock was felt simultaneously by

-both the observers.” (<i>Priestley’s History of Electricity.</i>) Subsequently

-the same parties made experiments near Shooter’s

-Hill, when the wires formed a circuit of four miles, and conveyed

-the shock with equal facility,&mdash;“a distance which without

-trial,” they observed, “was too great to be credited.”<a name="FNanchor_52" id="FNanchor_52" href="#Footnote_52" class="fnanchor">52</a> These

-experiments in 1747 established two great principles: 1, that

-the electric current is transmissible along nearly two miles and

-a half of iron wire; 2, that the electric current may be completed

-by burying the poles in the earth at the above distance.</p>

-

-<p>In the following year, 1748, Benjamin Franklin performed

-his celebrated experiments on the banks of the Schuylkill, near

-Philadelphia; which being interrupted by the hot weather, they

-were concluded by a picnic, when spirits were fired by an electric

-spark sent through a wire in the river, and a turkey was

-killed by the electric shock, and roasted by the electric jack

-before a fire kindled by the electrified bottle.</p>

-

-<p>In the year 1753, there appeared in the <i>Scots’ Magazine</i>, vol.

-xv., definite proposals for the construction of an electric telegraph,

-requiring as many conducting wires as there are letters

-in the alphabet; it was also proposed to converse by chimes,

-by substituting bells for the balls. A similar system of telegraphing

-was next invented by Joseph Bozolus, a Jesuit, at

-Rome; and next by the great Italian electrician Tiberius Cavallo,

-in his treatise on Electricity.</p>

-

-<p>In 1787, Arthur Young, when travelling in France, saw a

-model working telegraph by M. Lomond: “You write two or

-three words on a paper,” says Young; “he takes it with him

-into a room, and turns a machine enclosed in a cylindrical case,<span class="pagenum"><a name="Page_223" id="Page_223">223</a></span>

-at the top of which is an electrometer&mdash;a small fine pith-ball;

-a wire connects with a similar cylinder and electrometer in a

-distant apartment; and his wife, by remarking the corresponding

-motions of the ball, writes down the words they indicate:

-from which it appears that he has formed an alphabet of motions.

-As the length of the wire makes no difference in the

-effect, a correspondence might be carried on at any distance.

-Whatever the use may be, the invention is beautiful.”</p>

-

-<p>We now reach a new epoch in the scientific period&mdash;the discovery

-of the Voltaic Pile. In 1794, according to <i>Voigt’s Magazine</i>,

-Reizen made use of the electric spark for the telegraph;

-and in 1798 Dr. Salva of Madrid constructed a similar telegraph,

-which the Prince of Peace subsequently exhibited to the

-King of Spain with great success.</p>

-

-<p>In 1809, Soemmering exhibited a telegraphic apparatus

-worked by galvanism before the Academy of Sciences at Munich,

-in which the mode of signalling consisted in the development

-of gas-bubbles from the decomposition of water placed in a

-series of glass tubes, each of which denoted a letter of the alphabet.

-In 1813, Mr. Sharpe, of Doe Hill near Alfreton, devised

-a <i>voltaic</i>-electric telegraph, which he exhibited to the

-Lords of the Admiralty, who spoke approvingly of it, but declined

-to carry it into effect. In the following year, Soemmering

-exhibited a <i>voltaic</i>-electric telegraph of his own construction,

-which, however, was open to the objection of there being as

-many wires as signs or letters of the alphabet.</p>

-

-<p>The next invention is of much greater importance. Upon

-the suggestion of Cavallo, already referred to, Francis Ronalds

-constructed a perfect electric telegraph, employing frictional

-electricity notwithstanding Volta’s discoveries had been known

-in England for sixteen years. This telegraph was exhibited at

-Hammersmith in 1816:<a name="FNanchor_53" id="FNanchor_53" href="#Footnote_53" class="fnanchor">53</a> it consisted of a single insulated wire,

-the indication being by pith-balls in front of a dial. When the

-wire was charged, the balls were divergent, but collapsed when

-the wire was discharged; at the same time were employed two

-clocks, with lettered discs for the signals. “If, as Paley asserts

-(and Coleridge denies), ‘he alone discovers who proves,’ Ronalds

-is entitled to the appellation of the first discoverer of an

-efficient electric telegraph.” (<i>Saturday Review</i>, No. 147<a name="FNanchor_54" id="FNanchor_54" href="#Footnote_54" class="fnanchor">54</a>) Nevertheless

-the Government of the day refused to avail itself of this

-admirable contrivance.</p>

-

-<p>In 1819, Oersted made his great discovery of the deflection,

-by a current of electricity, of a magnetic needle at right angles<span class="pagenum"><a name="Page_224" id="Page_224">224</a></span>

-to such current. Dr. Hamel of St. Petersburg states that

-Baron Schilling was the first to apply Oersted’s discovery to

-telegraphy; Ampère had previously suggested it, but his plan

-was very complicated, and Dr. Hamel maintains that Schilling

-first realised the idea by actually producing an electro-magnetic

-telegraph simpler in construction than that which

-Ampère had <i>imagined</i>. In 1836, Professor Muncke of Heidelberg,

-who had inspected Schilling’s telegraphic apparatus, explained

-the same to William Fothergill Cooke, who in the

-following year returned to England, and subsequently, with

-Professor Wheatstone, laboured simultaneously for the introduction

-of the electro-magnetic telegraph upon the English

-railways; the first patent for which was taken out in the joint

-names of these two gentlemen.</p>

-

-<p>In 1844, Professor Wheatstone, with one of his telegraphs,

-formed a communication between King’s College and the lofty

-shot-tower on the opposite bank of the Thames: the wire was

-laid along the parapets of the terrace of Somerset House and

-Waterloo Bridge, and thence to the top of the tower, about 150

-feet high, where a telegraph was placed; the wire then descended,

-and a plate of zinc attached to its extremity was

-plunged into the mud of the river, whilst a similar plate attached

-to the extremity at the north side was immersed in the

-water. The circuit was thus completed by the entire breadth

-of the Thames, and the telegraph acted as well as if the circuit

-were entirely metallic.</p>

-

-<p>Shortly after this experiment, Professor Wheatstone and

-Mr. Cooke laid down the first working electric telegraph on the

-Great Western Railway, from Paddington to Slough.</p>

-

-<h3>ELECTRIC GIRDLE FOR THE EARTH.</h3>

-

-<p>One of our most profound electricians is reported to have

-exclaimed: “Give me but an unlimited length of wire, with a

-small battery, and I will girdle the universe with a sentence in

-forty minutes.” Yet this is no vain boast; for so rapid is the

-transition of the electric current along the line of the telegraph

-wire, that, supposing it were possible to carry the wires eight

-times round the earth, the transit would occupy but <i>one second

-of time</i>!</p>

-

-<h3>CONSUMPTION OF THE ELECTRIC TELEGRAPH.</h3>

-

-<p>It is singular to see how this telegraphic agency is measured

-by the chemical consumption of zinc and acid. Mr. Jones

-(who has written a work upon the Electric Telegraphs of America)

-estimates that to work 12,000 miles of telegraph about

-3000 zinc cups are used to hold the acid: these weigh about

-9000 lbs., and they undergo decomposition by the galvanic<span class="pagenum"><a name="Page_225" id="Page_225">225</a></span>

-action in about six months, so that 18,000 lbs. of zinc are consumed

-in a year. There are also about 3600 porcelain cups to

-contain nitric acid; it requires 450 lbs. of acid to charge them

-once, and the charge is renewed every fortnight, making about

-12,000 lbs. of nitric acid in a year.</p>

-

-<h3>TIME LOST IN ELECTRIC MESSAGES.</h3>

-

-<p>Although it may require an hour, or two or three hours, to

-transmit a telegraphic message to a distant city, yet it is the

-mechanical adjustment by the sender and receiver which really

-absorbs this time; the actual transit is practically instantaneous,

-and so it would be from here to the antipodes, so far as

-the current itself is concerned.</p>

-

-<h3>THE ELECTRIC TELEGRAPH IN ASTRONOMY AND THE

-DETERMINATION OF LONGITUDE.</h3>

-

-<p>The Electric Telegraph has become an instrument in the

-hands of the astronomer for determining the difference of longitude

-between two observatories. Thus in 1854 the difference

-of longitude between London and Paris was determined within

-a limit of error which amounted barely to a quarter of a second.

-The sudden disturbances of the magnetic needle, when freely

-suspended, which seem to take place simultaneously over whole

-continents, if not over the whole globe, from some unexplained

-cause, are pointed out as means by which the differences of longitude

-between the magnetic observatories may possibly be determined

-with greater precision than by any yet known method.</p>

-

-<p>So long ago as 1839 Professor Morse suggested some experiments

-for the determination of Longitudes; and in June

-1844 the difference of longitude between Washington and Baltimore

-was determined by electric means under his direction.

-Two persons were stationed at these two towns, with clocks

-carefully adjusted to the respective spots; and a telegraphic

-signal gave the means of comparing the two clocks at a given

-instant. In 1847 the relative longitudes of New York, Philadelphia,

-and Washington were determined by means of the

-electric telegraph by Messrs. Keith, Walker, and Loomis.</p>

-

-<h3>NON-INTERFERENCE OF GALVANIC WAVES ON THE SAME WIRE.</h3>

-

-<p>One of the most remarkable facts in the economy of the

-telegraph is, that the line, when connected with a battery in

-action, propagates the hydro-galvanic waves in either direction

-without interference. As several successive syllables of sound

-may set out in succession from the same place, and be on their

-way at the same time, to a listener at a distance, so also, where

-the telegraph-line is long enough, several waves may be on

-their way from the signal station before the first one reaches<span class="pagenum"><a name="Page_226" id="Page_226">226</a></span>

-the receiving station; two persons at a distance may pronounce

-several syllables at the same time, and each hear those

-emitted by the other. So, on a telegraph-line of two or three

-thousand miles in length in the air, and the same in the

-ground, two operators may at the same instant commence a

-series of several dots and lines, and each receive the other’s

-writings, though the waves have crossed each other on the way.</p>

-

-<h3>EFFECT OF LIGHTNING UPON THE ELECTRIC TELEGRAPH.</h3>

-

-<p>In the storm of Sunday April 2, 1848, the lightning had a

-very considerable effect on the wires of the electric telegraph,

-particularly on the line of railway eastward from Manchester

-to Normanton. Not only were the needles greatly deflected,

-and their power of answering to the handles considerably weakened,

-but those at the Normanton station were found to have

-had their poles reversed by some action of the electric fluid in

-the atmosphere. The damage, however, was soon repaired, and

-the needles again put in good working order.</p>

-

-<h3>ELECTRO-TELEGRAPHIC MESSAGE TO THE STARS.</h3>

-

-<p>The electric fluid travels at the mean rate of 20,000 miles

-in a second under ordinary circumstances; therefore, if it were

-possible to establish a telegraphic communication with the star

-61 Cygni, it would require ninety years to send a message there.</p>

-

-<p>Professor Henderson and Mr. Maclear have fully confirmed

-the annual parallax of α Centauri to amount to a second of arc,

-which gives about twenty billions of miles as its distance from

-our system; a ray of light would arrive from α Centauri to us in

-little more than three years, and a telegraphic despatch would

-arrive there in thirty years.</p>

-

-<h3>THE ATLANTIC TELEGRAPH.</h3>

-

-<p>The telegraphic communication between England and the

-United States is so grand a conception, that it would be impossible

-to detail its scientific and mechanical relations within the

-limits of the present work. All that we shall attempt, therefore,

-will be to glance at a few of the leading operations.</p>

-

-<p>In the experiments made before the Atlantic Telegraph was

-finally decided on, 2000 miles of subterranean and submarine

-telegraphic wires, ramifying through England and Ireland and

-under the waters of the Irish Sea, were specially connected for

-the purpose; and through this distance of 2000 miles 250 distinct

-signals were recorded and printed in one minute.</p>

-

-<p>First, as to the <i>Cable</i>. In the ordinary wires by the side of

-a railway the electric current travels on with the speed of lightning&mdash;uninterrupted

-by the speed of lightning; but when a

-wire is encased in gutta-percha, or any similar covering, for submersion<span class="pagenum"><a name="Page_227" id="Page_227">227</a></span>

-in the sea, new forces come into play. The electric excitement

-of the wire acts by induction, through the envelope,

-upon the particles of water in contact with that envelope, and

-calls up an electric force of an opposite kind. There are two

-forces, in fact, pulling against each other through the gutta-percha

-as a neutral medium,&mdash;that is, the electricity in the

-wire, and the opposite electricity in the film of water immediately

-surrounding the cable; and to that extent the power of

-the current in the enclosed wire is weakened. A submarine

-cable, when in the water, is virtually <i>a lengthened-out Leyden

-jar</i>; it transmits signals while being charged and discharged,

-instead of merely allowing a stream to flow evenly along it: it

-is a <i>bottle</i> for holding electricity rather than a <i>pipe</i> for carrying

-it; and this has to be filled for every time of using. The wire

-being carried underground, or through the water, the speed becomes

-quite measurable, say a thousand miles in a second, instead

-of two hundred thousand, owing to the retardation by induced

-or retrograde currents. The energy of the currents and

-the quality of the wire also affect the speed. Until lately it

-was supposed that the wire acts only as a <i>conductor</i> of electricity,

-and that a long wire must produce a weaker effect than a

-short one, on account of the consequent attenuation of the electrical

-influence; but it is now known that, the cable being a <i>reservoir</i>

-as well as a conductor, its electrical supply is increased

-in proportion to its length.</p>

-

-<p>The electro-magnetic current is employed, since it possesses

-a treble velocity of transmission, and realises consequently <i>a

-threefold working speed</i> as compared with simple voltaic electricity.

-Mr. Wildman Whitehouse has determined by his ingenious

-apparatus that the speed of the voltaic current might be

-raised under special circumstances to 1800 miles per second;

-but that of the induced current, or the electro-magnetic, might

-be augmented to 6000 miles per second.</p>

-

-<p>Next as to a <i>Quantity Battery</i> employed in these investigations.

-To effect a charge, and transmit a current through some

-thousand miles of the Atlantic Cable, Mr. Whitehouse had a

-piece of apparatus prepared consisting of twenty-five pairs of

-zinc and silver plates about the 20th part of a square inch

-large, and the pairs so arranged that they would hold a drop of

-acidulated water or brine between them. On charging this Lilliputian

-battery by dipping the plates in salt and water, messages

-were sent from it through a thousand miles of cable with

-the utmost ease; and not only so,&mdash;pair after pair was dropped

-out from the series, the messages being still sent on with equal

-facility, until at last only a single pair, charged by one single

-drop of liquid, was used. Strange to say, with this single pair

-and single drop distinct signals were effected through the thousand<span class="pagenum"><a name="Page_228" id="Page_228">228</a></span>

-miles of the cable! Each signal was registered at the end

-of the cable in less than three seconds of time.</p>

-

-<p>The entire length of wire, iron and copper, spun into the

-cable amounts to 332,500 miles, a length sufficient to engirdle

-the earth thirteen times. The cable weighs from 19 cwt. to a

-ton per mile, and will bear a strain of 5 tons.</p>

-

-<p>The <i>Perpetual Maintenance Battery</i>, for working the cable at

-the bottom of the sea, consists of large plates of platinated silver

-and amalgamated zinc, mounted in cells of gutta-percha.

-The zinc plates in each cell rest upon a longitudinal bar at the

-bottom, and the silver plates hang upon a similar bar at the top

-of the cell; so that there is virtually but a single stretch of

-silver and a single stretch of zinc in operation. Each of the

-ten cells contains 2000 square inches of acting surface; and

-the combination is so powerful, that when the broad strips of

-copper-plate which form the polar extensions are brought into

-contact or separated, brilliant flashes are produced, accompanied

-by a loud crackling sound. The points of large pliers are

-made red-hot in five seconds when placed between them, and

-even screws burn with vivid scintillation. The cost of maintaining

-this magnificent ten-celled Titan battery at work does

-not exceed a shilling per hour. The voltaic current generated

-in this battery is not, however, the electric stream to be sent

-across the Atlantic, but is only the primary power used to call

-up and stimulate the energy of a more speedy traveller by a

-complicated apparatus of “Double Induction Coils.” Nor is

-the transmission-current generated in the inner wire of the

-double induction coil,&mdash;and which becomes weakened when it

-has passed through 1800 or 1900 miles,&mdash;set to work to print or

-record the signals transmitted. This weakened current merely

-opens and closes the outlet of a fresh battery, which is to do

-the printing labour. This relay-instrument (as it is called),

-which consists of a temporary and permanent magnet, is so sensitive

-an apparatus, that it may be put in action by a fragment

-of zinc and a sixpence pressed against the tongue.</p>

-

-<p>The attempts to lay the cable in August 1857 failed through

-stretching it so tightly that it snapped and went to the bottom,

-at a depth of 12,000 feet, forty times the height of St. Paul’s.</p>

-

-<p>This great work was resumed in August 1858; and on the

-5th the first signals were received through <i>two thousand and

-fifty miles</i> of the Atlantic Cable. And it is worthy of remark,

-that just 111 years previously, on the 5th of August 1747, Dr.

-Watson astonished the scientific world by practically proving

-that the electric current could be transmitted through a <i>wire

-hardly two miles and a half long</i>.<a name="FNanchor_55" id="FNanchor_55" href="#Footnote_55" class="fnanchor">55</a></p>

-

-<hr />

-

-<p><span class="pagenum"><a name="Page_229" id="Page_229">229</a></span></p>

-

-<div class="chapter"></div>

-<h2><a name="Miscellanea" id="Miscellanea"></a>Miscellanea.</h2>

-

-<h3>HOW MARINE CHRONOMETERS ARE RATED AT THE ROYAL

-OBSERVATORY, GREENWICH.</h3>

-

-<p>The determination of the Longitude at Sea requires simply

-accurate instruments for the measurement of the positions of

-the heavenly bodies, and one or other of the two following,&mdash;either

-perfectly correct watches&mdash;or chronometers, as they are

-now called&mdash;or perfectly accurate tables of the lunar motions.</p>

-

-<p>So early as 1696 a report was spread among the members of

-the Royal Society that Sir Isaac Newton was occupied with the

-problem of finding the longitude at sea; but the rumour having

-no foundation, he requested Halley to acquaint the members

-“that he was not about it.”<a name="FNanchor_56" id="FNanchor_56" href="#Footnote_56" class="fnanchor">56</a> (<i>Sir David Brewster’s Life of

-Newton.</i>)</p>

-

-<p>In 1714 the legislature of Queen Anne passed an Act offering

-a reward of 20,000<i>l.</i> for the discovery of the longitude, the

-problem being then very inaccurately solved for want of good

-watches or lunar tables. About the year 1749, the attention

-of the Royal Society was directed to the improvements effected

-in the construction of watches by John Harrison, who received

-for his inventions the Copley Medal. Thus encouraged, Harrison

-continued his labours with unwearied diligence, and

-produced in 1758 a timekeeper which was sent for trial on a

-voyage to Jamaica. After 161 days the error of the instrument

-was only 1<sup>m</sup> 5<sup>s</sup>, and the maker received from the nation

-5000<i>l.</i> The Commissioners of the Board of Longitude subsequently

-required Harrison to construct under their inspection

-chronometers of a similar nature, which were subjected to

-trial in a voyage to Barbadoes, and performed with such accuracy,

-that, after having fully explained the principle of their

-construction to the commissioners, they awarded him 10,000<i>l.</i>

-more; at the same time Euler of Berlin and the heirs of Mayer

-of Göttingen received each 3000<i>l.</i> for their lunar tables.</p>

-

-<p><span class="pagenum"><a name="Page_230" id="Page_230">230</a></span></p>

-

-<blockquote>

-

-<p>The account of the trial of Harrison’s watch is very interesting. In

-April 1766, by desire of the Commissioners of the Board, the Lords of

-the Admiralty delivered the watch into the custody of the Astronomer-Royal,

-the Rev. Dr. Nevil Maskelyne. It was then placed at the Royal

-Observatory at Greenwich, in a box having two different locks, fixed to

-the floor or wainscot, with a plate of glass in the lid of the box, so that

-it might be compared as often as convenient with the regulator and the

-variation set down. The form observed by Mr. Harrison in winding up

-the watch was exactly followed; and an officer of Greenwich Hospital

-attended every day, at a stated hour, to see the watch wound up, and

-its comparison with the regulator entered. A key to one of the locks

-was kept at the Hospital for the use of the officer, and the other remained

-at the Observatory for the use of the Astronomer-Royal or his

-assistant.</p>

-

-<p>The watch was then tried in various positions till the beginning of

-July; and from thence to the end of February following in a horizontal

-position with its face upwards.</p>

-

-<p>The variation of the watch was then noted down, and a register was

-kept of the barometer and thermometer; and the time of comparing

-the same with the regulator was regularly kept, and attested by the

-Astronomer-Royal or his assistant and such of the officers as witnessed

-the winding-up and comparison of the watch.</p>

-

-<p>Under these conditions Harrison’s watch was received by the Astronomer-Royal

-at the Admiralty on May 5, 1766, in the presence of Philip

-Stephens, Esq., Secretary of the Admiralty; Captain Baillie, of the Royal

-Hospital, Greenwich; and Mr. Kendal the watchmaker, who accompanied

-the Astronomer-Royal to Greenwich, and saw the watch started

-and locked up in the box provided for it. The watch was then compared

-with the transit clock daily, and wound up in the presence of the

-officer of Greenwich Hospital. From May 5 to May 17 the watch was

-kept in a horizontal position with its face upwards; from May 18 to

-July 6 it was tried&mdash;first inclined at an angle of 20° to the horizon, with

-the face upwards, and the hours 12, 6, 3, and 9, highest successively;

-then in a vertical position, with the same hours highest in order; lastly,

-in a horizontal position with the face downwards. From July 16, 1766,

-to March 4, 1767, it was always kept in a horizontal position with its

-face upwards, lying upon the same cushion, and in the same box in

-which Mr. Harrison had kept it in the voyage to Barbadoes.</p>

-

-<p>From the observed transits of the sun over the meridian, according

-to the time of the regulator of the Observatory, together with the attested

-comparisons of Mr. Harrison’s watch with the transit clock, the

-watch was found too fast on several days as follows:</p>

-

-<table summary="Harrison's watch too fast">

-  <tr>

-    <td> </td>

-    <td> </td>

-    <td> </td>

-    <td class="tdc lrpad">h.</td>

-    <td class="tdr lrpad">m.</td>

-    <td class="tdc">s.</td></tr>

-  <tr>

-    <td class="tdl">1766.</td>

-    <td class="tdl">May 6</td>

-    <td class="tdc lrpad">too fast</td>

-    <td class="tdc">0</td>

-    <td class="tdr lrpad">0</td>

-    <td class="tdc">16·2</td></tr>

-  <tr>

-    <td> </td>

-    <td class="tdl">May 17</td>

-    <td class="tdc">”</td>

-    <td class="tdc">0</td>

-    <td class="tdr lrpad">3</td>

-    <td class="tdc">51·8</td></tr>

-  <tr>

-    <td> </td>

-    <td class="tdl">July 6</td>

-    <td class="tdc">”</td>

-    <td class="tdc">0</td>

-    <td class="tdr lrpad">14</td>

-    <td class="tdc">14·0</td></tr>

-  <tr>

-    <td> </td>

-    <td class="tdl">Aug. 6</td>

-    <td class="tdc">”</td>

-    <td class="tdc">0</td>

-    <td class="tdr lrpad">23</td>

-    <td class="tdc">58·4</td></tr>

-  <tr>

-    <td> </td>

-    <td class="tdl">Sept. 17</td>

-    <td class="tdc">”</td>

-    <td class="tdc">0</td>

-    <td class="tdr lrpad">32</td>

-    <td class="tdc">15·6</td></tr>

-  <tr>

-    <td> </td>

-    <td class="tdl">Oct. 29</td>

-    <td class="tdc">”</td>

-    <td class="tdc">0</td>

-    <td class="tdr lrpad">42</td>

-    <td class="tdc">20·9</td></tr>

-  <tr>

-    <td> </td>

-    <td class="tdl">Dec. 10</td>

-    <td class="tdc">”</td>

-    <td class="tdc">0</td>

-    <td class="tdr lrpad">54</td>

-    <td class="tdc">46·8</td></tr>

-  <tr>

-    <td class="tdl">1767.</td>

-    <td class="tdl">Jan. 21</td>

-    <td class="tdc">”</td>

-    <td class="tdc">1</td>

-    <td class="tdr lrpad">0</td>

-    <td class="tdc">28·6</td></tr>

-  <tr>

-    <td> </td>

-    <td class="tdl">March 4</td>

-    <td class="tdc">”</td>

-    <td class="tdc">1</td>

-    <td class="tdr lrpad">11</td>

-    <td class="tdc">23·0</td></tr>

-</table>

-

-<p>From May 6, which was the day after the watch arrived at the Royal

-Observatory, to March 4, 1767, there were six periods of six weeks each

-in which the watch was tried in a horizontal position; when the gaining

-in these several periods was as follows:</p>

-

-<p><span class="pagenum"><a name="Page_231" id="Page_231">231</a></span></p>

-

-<table id="watchgains" summary="Harrison's watch gains">

-  <tr>

-    <td class="tdl first">During the first 6 weeks</td>

-    <td class="tdc lrpad">it gained</td>

-    <td class="tdl">13<sup>m</sup></td>

-    <td class="tdl">20<sup>s</sup>,</td>

-    <td class="tdc lrpad">answering to</td>

-    <td class="tdl">3°</td>

-    <td class="tdl">20′</td>

-    <td class="tdc">of longitude.</td></tr>

-  <tr>

-    <td class="tdl first">In the 2d period of 6<br />weeks (from Aug. 6<br />to Sept. 17)</td>

-    <td class="tdc">”</td>

-    <td class="tdl"> 8</td>

-    <td class="tdl">17</td>

-    <td class="tdc">”</td>

-    <td class="tdl">2</td>

-    <td class="tdl"> 4</td>

-    <td class="tdc">”</td></tr>

-  <tr>

-    <td class="tdl first">In the 3d period (from<br />Sept. 17 to Oct. 29)</td>

-    <td class="tdc">”</td>

-    <td class="tdl">10</td>

-    <td class="tdl"> 5</td>

-    <td class="tdc">”</td>

-    <td class="tdl">2</td>

-    <td class="tdl">31</td>

-    <td class="tdc">”</td></tr>

-  <tr>

-    <td class="tdl first">In the 4th period (from<br />Oct. 29 to Dec. 20)</td>

-    <td class="tdc">”</td>

-    <td class="tdl">12</td>

-    <td class="tdl">26</td>

-    <td class="tdc">”</td>

-    <td class="tdl">3</td>

-    <td class="tdl"> 6</td>

-    <td class="tdc">”</td></tr>

-  <tr>

-    <td class="tdl first">In the 5th period (from<br />Dec. 20 to Jan. 21)</td>

-    <td class="tdc">”</td>

-    <td class="tdl"> 5</td>

-    <td class="tdl">42</td>

-    <td class="tdc">”</td>

-    <td class="tdl">1</td>

-    <td class="tdl">25</td>

-    <td class="tdc">”</td></tr>

-  <tr>

-    <td class="tdl first">In the 6th period (from<br />Jan. 21 to Mar. 4)</td>

-    <td class="tdc">”</td>

-    <td class="tdl">10</td>

-    <td class="tdl">54</td>

-    <td class="tdc">”</td>

-    <td class="tdl">2</td>

-    <td class="tdl">43</td>

-    <td class="tdc">”</td></tr>

-</table>

-</blockquote>

-

-<p>It was thence concluded that Mr. Harrison’s watch could

-not be depended upon to keep the longitude within a West-India

-voyage of six weeks, nor to keep the longitude within

-half a degree for more than a fortnight; and that it must be

-kept in a place where the temperature was always some degrees

-above freezing.<a name="FNanchor_57" id="FNanchor_57" href="#Footnote_57" class="fnanchor">57</a> (However, Harrison’s watch, which was made

-by Mr. Kendal subsequently, succeeded so completely, that after

-it had been round the world with Captain Cook, in the years

-1772&ndash;1775, the second 10,000<i>l.</i> was given to Harrison.)</p>

-

-<p>In the Act of 12th Queen Anne, the comparison of chronometers

-was not mentioned in reference to the Observatory duties;

-but after this time they became a serious charge upon the Observatory,

-which, it must be admitted, is by far the best place

-to try chronometers: the excellence of the instruments, and the

-frequent observations of the heavenly bodies over the meridian,

-will always render the rate of going of the Observatory clock

-better known than can be expected of the clock in most other

-places.</p>

-

-<p>After Mr. Harrison’s watch was tried, some watches by Earnshaw,

-Mudge, and others, were rated and examined by the Astronomer-Royal.</p>

-

-<p>At the Royal Observatory, Greenwich, there are frequently

-above 100 chronometers being rated, and there have been as

-many as 170 at one time. They are rated daily by two observers,

-the process being as follows. At a certain time every

-day two assistants in charge repair to the chronometer-room,

-where is a time-piece set to true time; one winds up each with

-its own key, and the second follows after some little time and

-verifies the fact that each is wound. One assistant then looks

-at each watch in succession, counting the beats of the clock

-whilst he compares the chronometer by the eye; and in the

-course of a few seconds he calls out the second shown by the

-chronometer when the clock is at a whole minute. This number

-is entered in a book by the other assistant, and so on till

-all the chronometers are compared. Then the assistants change<span class="pagenum"><a name="Page_232" id="Page_232">232</a></span>

-places, the second comparing and the first writing down. From

-these daily comparisons the daily rates are deduced, by which

-the goodness of the watch is determined. The errors are of

-two classes&mdash;that of general bad workmanship, and that of

-over or under correction for temperature. In the room is an

-apparatus in which the watch may be continually kept at temperatures

-exceeding 100° by artificial heat; and outside the

-window of the room is an iron cage, in which they are subjected

-to low temperatures. The very great care taken with all chronometers

-sent to the Royal Observatory, as well as the perfect

-impartiality of the examination which each receives, afford

-encouragement to their manufacture, and are of the utmost

-importance to the safety and perfection of navigation.</p>

-

-<p>We have before us now the Report of the Astronomer-Royal

-on the Rates of Chronometers in the year 1854, in which the

-following are the successive weekly sums of the daily rates of

-the first there mentioned:</p>

-

-<table id="report" summary="Report of the Astronomer-Royal">

-  <tr>

-    <td class="tdl" colspan="3">Week ending</td>

-    <td class="tdc">secs.</td></tr>

-  <tr>

-    <td class="tdc">Jan.</td>

-    <td class="tdr">21,</td>

-    <td class="tdc lrpad">loss in the week</td>

-    <td class="tdc">2·2</td></tr>

-  <tr>

-    <td class="tdc">”</td>

-    <td class="tdr rpad">28</td>

-    <td class="tdc">”</td>

-    <td class="tdc">4·0</td></tr>

-  <tr>

-    <td class="tdc">Feb.</td>

-    <td class="tdr rpad">4</td>

-    <td class="tdc">”</td>

-    <td class="tdc">1·1</td></tr>

-  <tr>

-    <td class="tdc">”</td>

-    <td class="tdr rpad">11</td>

-    <td class="tdc">”</td>

-    <td class="tdc">5·0</td></tr>

-  <tr>

-    <td class="tdc">”</td>

-    <td class="tdr rpad">18</td>

-    <td class="tdc">”</td>

-    <td class="tdc">4·9</td></tr>

-  <tr>

-    <td class="tdc">”</td>

-    <td class="tdr rpad">25</td>

-    <td class="tdc">”</td>

-    <td class="tdc">5·5</td></tr>

-  <tr>

-    <td class="tdc">Mar.</td>

-    <td class="tdr rpad">4</td>

-    <td class="tdc">”</td>

-    <td class="tdc">6·0</td></tr>

-  <tr>

-    <td class="tdc">”</td>

-    <td class="tdr rpad">11</td>

-    <td class="tdc">”</td>

-    <td class="tdc">6·0</td></tr>

-  <tr>

-    <td class="tdc">”</td>

-    <td class="tdr rpad">18</td>

-    <td class="tdc">”</td>

-    <td class="tdc">1·5</td></tr>

-  <tr>

-    <td class="tdc">”</td>

-    <td class="tdr rpad">25</td>

-    <td class="tdc">”</td>

-    <td class="tdc">4·5</td></tr>

-  <tr>

-    <td class="tdc">Apr.</td>

-    <td class="tdr rpad">1</td>

-    <td class="tdc">”</td>

-    <td class="tdc">4·0</td></tr>

-  <tr>

-    <td class="tdc">”</td>

-    <td class="tdr rpad">8</td>

-    <td class="tdc">”</td>

-    <td class="tdc">1·5</td></tr>

-  <tr>

-    <td class="tdc">”</td>

-    <td class="tdr">15,</td>

-    <td class="tdc">gain in the week</td>

-    <td class="tdc">0·4</td></tr>

-  <tr>

-    <td class="tdc">Apr.</td>

-    <td class="tdr">22,</td>

-    <td class="tdc">”</td>

-    <td class="tdc">2·6</td></tr>

-  <tr>

-    <td class="tdc">”</td>

-    <td class="tdr">29,</td>

-    <td class="tdc">loss in the week</td>

-    <td class="tdc">1·4</td></tr>

-  <tr>

-    <td class="tdc">May</td>

-    <td class="tdr rpad">6</td>

-    <td class="tdc">”</td>

-    <td class="tdc">2·1</td></tr>

-  <tr>

-    <td class="tdc">”</td>

-    <td class="tdr rpad">13</td>

-    <td class="tdc">”</td>

-    <td class="tdc">3·0</td></tr>

-  <tr>

-    <td class="tdc">”</td>

-    <td class="tdr rpad">20</td>

-    <td class="tdc">”</td>

-    <td class="tdc">5·1</td></tr>

-  <tr>

-    <td class="tdc">”</td>

-    <td class="tdr rpad">27</td>

-    <td class="tdc">”</td>

-    <td class="tdc">3·3</td></tr>

-  <tr>

-    <td class="tdc">June</td>

-    <td class="tdr rpad">3</td>

-    <td class="tdc">”</td>

-    <td class="tdc">2·8</td></tr>

-  <tr>

-    <td class="tdc">”</td>

-    <td class="tdr rpad">10</td>

-    <td class="tdc">”</td>

-    <td class="tdc">1·8</td></tr>

-  <tr>

-    <td class="tdc">”</td>

-    <td class="tdr rpad">17</td>

-    <td class="tdc">”</td>

-    <td class="tdc">2·0</td></tr>

-  <tr>

-    <td class="tdc">”</td>

-    <td class="tdr rpad">24</td>

-    <td class="tdc">”</td>

-    <td class="tdc">3·0</td></tr>

-  <tr>

-    <td class="tdc">July</td>

-    <td class="tdr rpad">1</td>

-    <td class="tdc">”</td>

-    <td class="tdc">2·5</td></tr>

-  <tr>

-    <td class="tdc">”</td>

-    <td class="tdr rpad">8</td>

-    <td class="tdc">”</td>

-    <td class="tdc">1·2</td></tr>

-</table>

-

-<p>Till February 4 the watch was exposed to the external air

-outside a north window; from February 5 to March 4 it was

-placed in the chamber of a stove heated by gas to a moderate

-temperature; and from April 29 to May 20 it was placed in the

-chamber when heated to a high temperature.</p>

-

-<p>The advance in making chronometers since Harrison’s celebrated

-watch was tried at the Royal Observatory, more than

-ninety years since, may be judged by comparing its rates with

-those above.</p>

-

-<h3>GEOMETRY OF SHELLS.</h3>

-

-<p>There is a mechanical uniformity observable in the description

-of shells of the same species which at once suggests the

-probability that the generating figure of each increases, and

-that the spiral chamber of each expands itself, according to some

-simple geometrical law common to all. To the determination

-of this law the operculum lends itself, in certain classes of

-shells, with remarkable facility. Continually enlarged by the

-animal, as the construction of its shell advances so as to fill up<span class="pagenum"><a name="Page_233" id="Page_233">233</a></span>

-its mouth, the operculum measures the progressive widening of

-the spiral chamber by the progressive stages of its growth.</p>

-

-<div class="tb">* <span class="in2">* </span><span class="in2">* </span><span class="in2">* </span><span class="in2">*</span></div>

-

-<p>The animal, as he advances in the construction of his shell,

-increases continually his operculum, so as to adjust it to his

-mouth. He increases it, however, not by additions made at the

-same time all round its margin, but by additions made only on

-one side of it at once. One edge of the operculum thus remains

-unaltered as it is advanced into each new position, and

-placed in a newly-formed section of the chamber similar to the

-last but greater than it.</p>

-

-<p>That the same edge which fitted a portion of the first less

-section should be capable of adjustment so as to fit a portion

-of the next similar but greater section, supposes a geometrical

-provision in the curved form of the chamber of great complication

-and difficulty. But God hath bestowed upon this

-humble architect the practical skill of the learned geometrician;

-and he makes this provision with admirable precision in

-that curvature of the logarithmic spiral which he gives to the

-section of the shell. This curvature obtaining, he has only

-to turn his operculum slightly round in its own place, as he

-advances it into each newly-formed portion of his chamber, to

-adapt one margin of it to a new and larger surface and a different

-curvature, leaving the space to be filled up by increasing

-the operculum wholly on the outer margin.</p>

-

-<div class="tb">* <span class="in2">* </span><span class="in2">* </span><span class="in2">* </span><span class="in2">*</span></div>

-

-<p>Why the Mollusks, who inhabit turbinated and discoid shells,

-should, in the progressive increase of their spiral dwellings, affect

-the peculiar law of the logarithmic spiral, is easily to be

-understood. Providence has subjected the instinct which

-shapes out each to a rigid uniformity of operation.&mdash;<i>Professor

-Mosely</i>: <i>Philos. Trans.</i> 1838.</p>

-

-<h3>HYDRAULIC THEORY OF SHELLS.</h3>

-

-<p>How beautifully is the wisdom of God developed in shaping

-out and moulding shells! and especially in the particular value

-of the constant angle which the spiral of each species of shell

-affects,&mdash;a value connected by a necessary relation with the

-economy of the material of each, and with its stability and

-the conditions of its buoyancy. Thus the shell of the <i>Nautilus

-Pompilius</i> has, hydrostatically, an A-statical surface. If placed

-with any portion of its surface upon the water, it will immediately

-turn over towards its smaller end, and rest only on its

-mouth. Those conversant with the theory of floating bodies

-will recognise in this an interesting property.&mdash;<i>Ibid.</i></p>

-

-<p><span class="pagenum"><a name="Page_234" id="Page_234">234</a></span></p>

-

-<h3>SERVICES OF SEA-SHELLS AND ANIMALCULES.</h3>

-

-<p>Dr. Maury is disposed to regard these beings as having much

-to do in maintaining the harmonies of creation, and the principles

-of the most admirable compensation in the system of

-oceanic circulation. “We may even regard them as regulators,

-to some extent, of climates in parts of the earth far removed

-from their presence. There is something suggestive

-both of the grand and the beautiful in the idea that while the

-insects of the sea are building up their coral islands in the perpetual

-summer of the tropics, they are also engaged in dispensing

-warmth to distant parts of the earth, and in mitigating the

-severe cold of the polar winter.”</p>

-

-<h3>DEPTH OF THE PRIMEVAL SEAS.</h3>

-

-<p>Professor Forbes, in a communication to the Royal Society,

-states that not only the colour of the shells of existing mollusks

-ceases to be strongly marked at considerable depths, but also

-that well-defined patterns are, with very few and slight exceptions,

-presented only by testacea inhabiting the littoral, circumlittoral,

-and median zones. In the Mediterranean, only one in

-eighteen of the shells taken from below 100 fathoms exhibit

-any markings of colour, and even the few that do so are questionable

-inhabitants of those depths. Between 30 and 35 fathoms,

-the proportion of marked to plain shells is rather less

-than one in three; and between the margin and two fathoms

-the striped or mottled species exceed one-half of the total number.

-In our own seas, Professor Forbes observes that testacea

-taken from below 100 fathoms, even when they are individuals

-of species vividly striped or banded in shallower zones, are quite

-white or colourless. At between 60 and 80 fathoms, striping

-and banding are rarely presented by our shells, especially in the

-northern provinces; from 50 fathoms, shallow bands, colours,

-and patterns, are well marked. <i>The relation of these arrangements

-of colour to the degree of light penetrating the different zones

-of depth</i> is a subject well worthy of minute inquiry.</p>

-

-<h3>NATURAL WATER-PURIFIERS.</h3>

-

-<p>Mr. Warrington kept for a whole year twelve gallons of water

-in a state of admirably balanced purity by the following beautiful

-action:</p>

-

-<blockquote>

-

-<p>In the tank, or aquarium, were two gold fish, six water-snails, and

-two or three specimens of that elegant aquatic plant <i>Valisperia sporalis</i>,

-which, before the introduction of the water-snails, by its decayed

-leaves caused a growth of slimy mucus, and made the water turbid and

-likely to destroy both plants and fish. But under the improved arrangement

-the slime, as fast as it was engendered, was consumed by

-the water-snails, which reproduced it in the shape of young snails, which<span class="pagenum"><a name="Page_235" id="Page_235">235</a></span>

-furnished a succulent food to the fish. Meanwhile the <i>Valisperia</i> plants

-absorbed the carbonic acid exhaled by the respiration of their companions,

-fixing the carbon in their growing stems and luxuriant blossoms,

-and refreshing the oxygen (during sunshine in visible little streams) for

-the respiration of the snails and the fish. The spectacle of perfect equilibrium

-thus simply maintained between animal, vegetable, and inorganic

-activity, was strikingly beautiful; and such means might possibly

-hereafter be made available on a large scale for keeping tanked water

-sweet and clean.&mdash;<i>Quarterly Review</i>, 1850.</p></blockquote>

-

-<h3>HOW TO IMITATE SEA-WATER.</h3>

-

-<p>The demand for Sea-water to supply the Marine Aquarium&mdash;now

-to be seen in so many houses&mdash;induced Mr. Gosse to attempt

-the manufacture of Sea-water, more especially as the

-constituents are well known. He accordingly took Scheveitzer’s

-analysis of Sea-water for his guide. In one thousand

-grains of sea-water taken off Brighton, it gave: water, 964·744;

-chloride of sodium, 27·059; chloride of magnesium, 3·666;

-chloride of potassium, 9·755; bromide of magnesium, 0·29;

-sulphate of magnesia, 2·295; sulphate of lime, 1·407; carbonate

-of lime, 0·033: total, 999·998. Omitting the bromide of

-magnesium, the carbonate of lime, and the sulphate of lime, as

-being very small quantities, the component parts were reduced

-to common salt, 3½ oz.; Epsom salts, ¼ oz.; chloride of magnesium,

-200 grains troy; chloride of potassium, 40 grains

-troy; and four quarts of water. Next day the mixture was

-filtered through a sponge into a glass jar, the bottom covered

-with shore-pebbles and fragments of stone and fronds of green

-sea-weed. A coating of green spores was soon deposited on the

-sides of the glass, and bubbles of oxygen were copiously thrown

-off every day under the excitement of the sun’s light. In a

-week Mr. Gosse put in species of <i>Actinia Bowerbankia</i>, <i>Cellularia</i>,

-<i>Serpula</i>, &amp;c. with some red sea-weeds; and the whole

-throve well.</p>

-

-<h3>VELOCITY OF IMPRESSIONS TRANSMITTED TO THE BRAIN.</h3>

-

-<p>Professor Helmholtz of Königsberg has, by the electro-magnetic

-method,<a name="FNanchor_58" id="FNanchor_58" href="#Footnote_58" class="fnanchor">58</a> ascertained that the intelligence of an impression

-made upon the ends of the nerves in communication

-with the skin is transmitted to the brain with a velocity of

-about 195 feet per second. Arrived at the brain, about one-tenth

-of a second passes before the will is able to give the command

-to the nerves that certain muscles shall execute a certain

-motion, varying in persons and times. Finally, about 1/100th<span class="pagenum"><a name="Page_236" id="Page_236">236</a></span>

-of a second passes after the receipt of the command before the

-muscle is in activity. In all, therefore, from the excitation

-of the sensitive nerves till the moving of the muscle, 1¼ to 2/10ths

-of a second are consumed. Intelligence from the great toe arrives

-about 1/30th of a second later than from the ear or the face.</p>

-

-<p>Thus we see that the differences of time in the nervous impressions,

-which we are accustomed to regard as simultaneous,

-lie near our perception. We are taught by astronomy that, on

-account of the time taken to propagate light, we now see what

-has occurred in the fixed stars years ago; and that, owing to

-the time required for the transmission of sound, we hear after

-we see is a matter of daily experience. Happily the distances

-to be traversed by our sensuous perceptions before they reach

-the brain are so short that we do not observe their influence,

-and are therefore unprejudiced in our practical interest. With

-an ordinary whale the case is perhaps more dubious; for in all

-probability the animal does not feel a wound near its tail until

-a second after it has been inflicted, and requires another second

-to send the command to the tail to defend itself.</p>

-

-<h3>PHOTOGRAPHS ON THE RETINA.</h3>

-

-<p>The late Rev. Dr. Scoresby explained with much minuteness

-and skill the varying phenomena which presented themselves

-to him after gazing intently for some time on strongly-illuminated

-objects,&mdash;as the sun, the moon, a red or orange or

-yellow wafer on a strongly-contrasted ground, or a dark object

-seen in a bright field. The doctor explained, upon removing

-the eyes from the object, the early appearance of the picture or

-image which had been thus “photographed on the Retina,”

-with the photochromatic changes which the picture underwent

-while it still retained its general form and most strongly-marked

-features; also, how these pictures, when they had almost faded

-away, could at pleasure, and for a considerable time, be renewed

-by rapidly opening and shutting the eyes.</p>

-

-<h3>DIRECT EXPLORATION OF THE INTERIOR OF THE EYE.</h3>

-

-<p>Dr. S. Wood of Cincinnati states, that by means of a small

-double convex lens of short focus held near the eye,&mdash;that organ

-looking through it at a candle twelve or fifteen feet distant,&mdash;there

-will be perceived a large luminous disc, covered with

-dark and light spots and dark streaks, which, after a momentary

-confusion, will settle down into an unchanging picture,

-which picture is composed of the organs or internal parts of the

-eye. The eye is thus enabled to view its own internal organisation,

-to have a beautiful exhibition of the vessels of the cornea,

-of the distribution of the lachrymas secretions in the act<span class="pagenum"><a name="Page_237" id="Page_237">237</a></span>

-of winking, and to see into the nature and cause of <i>muscæ volitantes</i>.</p>

-

-<h3>NATURE OF THE CANDLE-FLAME.</h3>

-

-<p>M. Volger has subjected this Flame to a new analysis.</p>

-

-<blockquote>

-

-<p>He finds that the so-called <i>flame-bud</i>, a globular blue flaminule, is

-first produced at the summit of the wick: this is the result of the combustion

-of carbonic oxide, hydrogen, and carbon, and is surrounded by

-a reddish-violet halo, the <i>veil</i>. The increased heat now gives rise to

-the actual flame, which shoots forth from the expanding bud, and is

-then surrounded at its inferior portion only by the latter. The interior

-consists of a dark gaseous cone, containing the immediate products of

-the decomposition of the fatty acids, and surrounded by another dark

-hollow cone, the <i>inner cap</i>. Here we already meet with carbon and

-hydrogen, which have resulted from the process of decomposition; and

-we distinguish this cone from the inner one by its yielding soot. The

-<i>external cap</i> constitutes the most luminous portion of the flame, in which

-the hydrogen is consumed and the carbon rendered incandescent. The

-surrounding portion is but slightly luminous, deposits no soot, and in it

-the carbon and hydrogen are consumed.&mdash;<i>Liebig’s Annual Report.</i></p></blockquote>

-

-<h3>HOW SOON A CORPSE DECAYS.</h3>

-

-<p>Mr. Lewis, of the General Board of Health, from his examination

-of the contents of nearly 100 coffins in the vaults and

-catacombs of London churches, concludes that the complete

-decomposition of a corpse, and its resolution into its ultimate

-elements, takes place in a leaden coffin with extreme slowness.

-In a wooden coffin the remains, with the exception of the bones,

-vanish in from two to five years. This period depends upon the

-quality of the wood, and the free access of air to the coffins.

-But in leaden coffins, 50, 60, 80, and even 100 years are required

-to accomplish this. “I have opened,” says Mr. Lewis,

-“a coffin in which the corpse had been placed for nearly a century;

-and the ammoniacal gas formed dense white fumes when

-brought in contact with hydrochloric-acid gas, and was so powerful

-that the head could not remain in it for more than a few

-seconds at a time.” To render the human body perfectly inert

-after death, it should be placed in a light wooden coffin, in a

-pervious soil, from five to eight feet deep.</p>

-

-<h3>MUSKET-BALLS FOUND IN IVORY.</h3>

-

-<p>The Ceylon sportsman, in shooting elephants, aims at a spot

-just above the proboscis. If he fires a little too low, the ball

-passes into the tusk-socket, causing great pain to the animal,

-but not endangering its life; and it is immediately surrounded

-by osteo-dentine. It has often been a matter of wonder how

-such bodies should become completely imbedded in the substance

-of the tusk, sometimes without any visible aperture; or

-how leaden bullets become lodged in the solid centre of a very<span class="pagenum"><a name="Page_238" id="Page_238">238</a></span>

-large tusk without having been flattened, as they are found by

-the ivory-turner.</p>

-

-<blockquote>

-

-<p>The explanation is as follows: A musket-ball aimed at the head of

-an elephant may penetrate the thin bony socket and the thinner ivory

-parietes of the wide conical pulp-cavity occupying the inserted base of

-the tusk; if the projectile force be there spent, the ball will gravitate

-to the opposite and lower side of the pulp-cavity. The pulp becomes

-inflamed, irregular calcification ensues, and osteo-dentine is formed

-around the ball. The pulp then resumes its healthy state and functions,

-and coats the osteo-dentine enclosing the ball, together with the root of

-the conical cavity into which the mass projects, with layers of normal

-ivory. The hole formed by the ball is soon replaced, and filled up by

-osteo-dentine, and coated with cement. Meanwhile, by the continued

-progress of growth, the enclosed ball is pushed forward to the middle of

-the solid tusk; or if the elephant be young, the ball may be carried

-forward by growth and wear of the tusk until its base has become the

-apex, and become finally exposed and discharged by the continual abrasion

-to which the apex of the tusk is subjected.&mdash;<i>Professor Owen.</i></p></blockquote>

-

-<h3>NATURE OF THE SUN.</h3>

-

-<p>To the article at pp. 59&ndash;60 should be added the result obtained

-by Dr. Woods of Parsonstown, and communicated to the

-<i>Philosophical Magazine</i> for July 1854. Dr. Woods, from photographic

-experiment, has no doubt that the light from the centre

-of flame acts more energetically than that from the edge on a

-surface capable of receiving its impression; and that light from

-a luminous solid body acts equally powerfully from its centre

-or its edges: wherefore Dr. Woods concludes that, as the sun

-affects a sensitive plate similarly with flame, it is probable its

-light-producing portion is of a similar nature.</p>

-

-<blockquote>

-

-<p><i>Note to</i> “<span class="smcap">Is the Heat of the Sun decreasing?</span>” <i>at page 65</i>.&mdash;Dr.

-Vaughan of Cincinnati has stated to the British Association:

-“From a comparison of the relative intensity of solar, lunar, and artificial

-light, as determined by Euler and Wollaston, it appears that the

-rays of the sun have an illuminating power equal to that of 14,000 candles

-at a distance of one foot, or of 3500,000000,000000,000000,000000

-candles at a distance of 95,000,000 miles. It follows that the amount

-of light which flows from the solar orb could be scarcely produced by

-the daily combustion of 200 globes of tallow, each equal to the earth in

-magnitude. A sphere of combustible matter much larger than the sun

-itself should be consumed every ten years in maintaining its wonderful

-brilliancy; and its atmosphere, if pure oxygen, would be expended before

-a few days in supporting so great a conflagration. An illumination

-on so vast a scale could be kept up only by the inexhaustible magazine

-of ether disseminated through space, and ever ready to manifest its luciferous

-properties on large spheres, whose attraction renders it sufficiently

-dense for the play of chemical affinity. Accordingly suns derive

-the power of shedding perpetual light, not from their chemical

-constitution, but from their immense mass and their superior attractive

-power.”</p></blockquote>

-

-<p><span class="pagenum"><a name="Page_239" id="Page_239">239</a></span></p>

-

-<h3>PLANETOIDS.</h3>

-

-<table id="planetoids" summary="Discoveries of the Planetoids">

-  <tr class="hdr smaller">

-    <td class="tdc bt bb">Name.</td>

-    <td class="tdc bt bb">Date of<br />Discovery.</td>

-    <td class="tdc bt bb">Discoverer.</td>

-    <td class="tdc bt bb">Place of<br />Discovery.</td>

-    <td class="tdc bt bb">No. discovered<br />by each<br />astronomer.</td></tr>

-  <tr>

-    <td class="tdl">Mercury, Mars,<br />Venus, Jupiter,<br />Earth, Saturn</td>

-    <td class="tdc">Known to the<br />ancients.</td>

-    <td class="tdc">...</td>

-    <td class="tdc">...</td>

-    <td class="tdc">&mdash;</td></tr>

-  <tr>

-    <td class="tdl">   Uranus</td>

-    <td class="tdl">1781, March 13</td>

-    <td class="tdl">W. Herschel</td>

-    <td class="tdl">Bath</td>

-    <td class="tdc">&mdash;</td></tr>

-  <tr>

-    <td class="tdl">   Neptune<a name="FNanchor_59" id="FNanchor_59" href="#Footnote_59" class="fnanchor">59</a></td>

-    <td class="tdl">1846, Sept. 23</td>

-    <td class="tdl">Galle</td>

-    <td class="tdl">Berlin</td>

-    <td class="tdc">&mdash;</td></tr>

-  <tr>

-    <td class="tdl"> 1 Ceres</td>

-    <td class="tdl">1801, Jan. 1</td>

-    <td class="tdl">Piazzi</td>

-    <td class="tdl">Palermo</td>

-    <td class="tdc">1</td></tr>

-  <tr>

-    <td class="tdl"> 2 Pallas</td>

-    <td class="tdl">1802, March 28</td>

-    <td class="tdl">Olbers</td>

-    <td class="tdl">Bremen</td>

-    <td class="tdc">1</td></tr>

-  <tr>

-    <td class="tdl"> 3 Juno</td>

-    <td class="tdl">1804, Sept. 1</td>

-    <td class="tdl">Harding</td>

-    <td class="tdl">Lilienthal</td>

-    <td class="tdc">1</td></tr>

-  <tr>

-    <td class="tdl"> 4 Vesta</td>

-    <td class="tdl">1807, March 29</td>

-    <td class="tdl">Olbers</td>

-    <td class="tdl">Bremen</td>

-    <td class="tdc">2</td></tr>

-  <tr>

-    <td class="tdl"> 5 Astræa</td>

-    <td class="tdl">1845, Dec. 8</td>

-    <td class="tdl">Encke</td>

-    <td class="tdl">Driesen</td>

-    <td class="tdc">1</td></tr>

-  <tr>

-    <td class="tdl"> 6 Hebe</td>

-    <td class="tdl">1847, July 1</td>

-    <td class="tdl">Encke</td>

-    <td class="tdl">Driesen</td>

-    <td class="tdc">2</td></tr>

-  <tr>

-    <td class="tdl"> 7 Iris</td>

-    <td class="tdl">1847, August 13</td>

-    <td class="tdl">Hind</td>

-    <td class="tdl">London</td>

-    <td class="tdc">1</td></tr>

-  <tr>

-    <td class="tdl"> 8 Flora</td>

-    <td class="tdl">1847, Oct. 18</td>

-    <td class="tdl">Hind</td>

-    <td class="tdl">London</td>

-    <td class="tdc">2</td></tr>

-  <tr>

-    <td class="tdl"> 9 Metis</td>

-    <td class="tdl">1848, April 25</td>

-    <td class="tdl">Graham</td>

-    <td class="tdl">Markree</td>

-    <td class="tdc">1</td></tr>

-  <tr>

-    <td class="tdl">10 Hygeia</td>

-    <td class="tdl">1849, April 12</td>

-    <td class="tdl">Gasperis</td>

-    <td class="tdl">Naples</td>

-    <td class="tdc">1</td></tr>

-  <tr>

-    <td class="tdl">11 Parthenope</td>

-    <td class="tdl">1850, May 11</td>

-    <td class="tdl">Gasperis</td>

-    <td class="tdl">Naples</td>

-    <td class="tdc">2</td></tr>

-  <tr>

-    <td class="tdl">12 Victoria</td>

-    <td class="tdl">1850, Sept. 13</td>

-    <td class="tdl">Hind</td>

-    <td class="tdl">London</td>

-    <td class="tdc">3</td></tr>

-  <tr>

-    <td class="tdl">13 Egeria</td>

-    <td class="tdl">1850, Nov. 2</td>

-    <td class="tdl">Gasperis</td>

-    <td class="tdl">Naples</td>

-    <td class="tdc">3</td></tr>

-  <tr>

-    <td class="tdl">14 Irene</td>

-    <td class="tdl">1851, May 19</td>

-    <td class="tdl">Hind</td>

-    <td class="tdl">London</td>

-    <td class="tdc">4</td></tr>

-  <tr>

-    <td class="tdl">15 Eunomia</td>

-    <td class="tdl">1851, July 29</td>

-    <td class="tdl">Gasperis</td>

-    <td class="tdl">Naples</td>

-    <td class="tdc">4</td></tr>

-  <tr>

-    <td class="tdl">16 Psyche</td>

-    <td class="tdl">1852, March 17</td>

-    <td class="tdl">Gasperis</td>

-    <td class="tdl">Naples</td>

-    <td class="tdc">5</td></tr>

-  <tr>

-    <td class="tdl">17 Thetis</td>

-    <td class="tdl">1852, April 17</td>

-    <td class="tdl">Luther</td>

-    <td class="tdl">Bilk</td>

-    <td class="tdc">1</td></tr>

-  <tr>

-    <td class="tdl">18 Melpomene</td>

-    <td class="tdl">1852, June 24</td>

-    <td class="tdl">Hind</td>

-    <td class="tdl">London</td>

-    <td class="tdc">5</td></tr>

-  <tr>

-    <td class="tdl">19 Fortuna</td>

-    <td class="tdl">1852, August 22</td>

-    <td class="tdl">Hind</td>

-    <td class="tdl">London</td>

-    <td class="tdc">6</td></tr>

-  <tr>

-    <td class="tdl">20 Massilia</td>

-    <td class="tdl">1852, Sept. 19</td>

-    <td class="tdl">Gasperis</td>

-    <td class="tdl">Naples</td>

-    <td class="tdc">6</td></tr>

-  <tr>

-    <td class="tdl">21 Lutetia</td>

-    <td class="tdl">1852, Nov. 15</td>

-    <td class="tdl">Goldschmidt</td>

-    <td class="tdl">Paris</td>

-    <td class="tdc">1</td></tr>

-  <tr>

-    <td class="tdl">22 Calliope</td>

-    <td class="tdl">1852, Nov. 16</td>

-    <td class="tdl">Hind</td>

-    <td class="tdl">London</td>

-    <td class="tdc">7</td></tr>

-  <tr>

-    <td class="tdl">23 Thalia</td>

-    <td class="tdl">1852, Dec. 15</td>

-    <td class="tdl">Hind</td>

-    <td class="tdl">London</td>

-    <td class="tdc">8</td></tr>

-  <tr>

-    <td class="tdl">24 Themis</td>

-    <td class="tdl">1853, April 5</td>

-    <td class="tdl">Gasperis</td>

-    <td class="tdl">Naples</td>

-    <td class="tdc">7</td></tr>

-  <tr>

-    <td class="tdl">25 Phocea</td>

-    <td class="tdl">1853, April 6</td>

-    <td class="tdl">Chacornac</td>

-    <td class="tdl">Marseilles</td>

-    <td class="tdc">1</td></tr>

-  <tr>

-    <td class="tdl">26 Proserpine</td>

-    <td class="tdl">1853, May 5</td>

-    <td class="tdl">Luther</td>

-    <td class="tdl">Bilk</td>

-    <td class="tdc">2</td></tr>

-  <tr>

-    <td class="tdl">27 Euterpe</td>

-    <td class="tdl">1853, Nov. 8</td>

-    <td class="tdl">Hind</td>

-    <td class="tdl">London</td>

-    <td class="tdc">9</td></tr>

-  <tr>

-    <td class="tdl">28 Bellona</td>

-    <td class="tdl">1854, March 1</td>

-    <td class="tdl">Luther</td>

-    <td class="tdl">Bilk</td>

-    <td class="tdc">3</td></tr>

-  <tr>

-    <td class="tdl">29 Amphitrite</td>

-    <td class="tdl">1854, March 1</td>

-    <td class="tdl">Marth</td>

-    <td class="tdl">London</td>

-    <td class="tdc">1</td></tr>

-  <tr>

-    <td class="tdl">30 Urania</td>

-    <td class="tdl">1854, July 22</td>

-    <td class="tdl">Hind</td>

-    <td class="tdl">London</td>

-    <td class="tdc">10 </td></tr>

-  <tr>

-    <td class="tdl">31 Euphrosyne</td>

-    <td class="tdl">1854, Sept. 1</td>

-    <td class="tdl">Furguson</td>

-    <td class="tdl">Washington</td>

-    <td class="tdc">1</td></tr>

-  <tr>

-    <td class="tdl">32 Pomona</td>

-    <td class="tdl">1854, Oct. 26</td>

-    <td class="tdl">Goldschmidt</td>

-    <td class="tdl">Paris</td>

-    <td class="tdc">2</td></tr>

-  <tr>

-    <td class="tdl">33 Polyhymnia</td>

-    <td class="tdl">1854, Oct. 28</td>

-    <td class="tdl">Chacornac</td>

-    <td class="tdl">Paris</td>

-    <td class="tdc">2</td></tr>

-  <tr>

-    <td class="tdl">34 Circe</td>

-    <td class="tdl">1855, April 6</td>

-    <td class="tdl">Chacornac</td>

-    <td class="tdl">Paris</td>

-    <td class="tdc">3</td></tr>

-  <tr>

-    <td class="tdl">35 Leucothea</td>

-    <td class="tdl">1855, April 19</td>

-    <td class="tdl">Luther</td>

-    <td class="tdl">Bilk</td>

-    <td class="tdc">4</td></tr>

-  <tr>

-    <td class="tdl">36 Atalante</td>

-    <td class="tdl">1855, Oct. 5</td>

-    <td class="tdl">Goldschmidt</td>

-    <td class="tdl">Paris</td>

-    <td class="tdc">3</td></tr>

-  <tr>

-    <td class="tdl">37 Fides</td>

-    <td class="tdl">1855, Oct. 5</td>

-    <td class="tdl">Luther</td>

-    <td class="tdl">Bilk</td>

-    <td class="tdc">5</td></tr>

-  <tr>

-    <td class="tdl">38 Leda</td>

-    <td class="tdl">1856, Jan. 12</td>

-    <td class="tdl">Chacornac</td>

-    <td class="tdl">Paris</td>

-    <td class="tdc">4</td></tr>

-  <tr>

-    <td class="tdl">39 Lætitia</td>

-    <td class="tdl">1856, Feb. 8</td>

-    <td class="tdl">Chacornac</td>

-    <td class="tdl">Paris</td>

-    <td class="tdc">5</td></tr>

-  <tr>

-    <td class="tdl">40 Harmonia</td>

-    <td class="tdl">1856, March 31</td>

-    <td class="tdl">Goldschmidt</td>

-    <td class="tdl">Paris</td>

-    <td class="tdc">4</td></tr>

-  <tr>

-    <td class="tdl">41 Daphne</td>

-    <td class="tdl">1856, May 22</td>

-    <td class="tdl">Goldschmidt</td>

-    <td class="tdl">Paris</td>

-    <td class="tdc">5</td></tr>

-  <tr>

-    <td class="tdl">42 Isis</td>

-    <td class="tdl">1856, May 23</td>

-    <td class="tdl">Pogson</td>

-    <td class="tdl">Oxford</td>

-    <td class="tdc">1</td></tr>

-  <tr>

-    <td class="tdl">43 Ariadne</td>

-    <td class="tdl">1857, April 15</td>

-    <td class="tdl">Pogson</td>

-    <td class="tdl">Oxford</td>

-    <td class="tdc">2</td></tr>

-  <tr>

-    <td class="tdl">44 Nysa</td>

-    <td class="tdl">1857, May 27</td>

-    <td class="tdl">Goldschmidt</td>

-    <td class="tdl">Paris</td>

-    <td class="tdc">6</td></tr>

-  <tr>

-    <td class="tdl">45 Eugenia</td>

-    <td class="tdl">1857, June 28</td>

-    <td class="tdl">Goldschmidt</td>

-    <td class="tdl">Paris</td>

-    <td class="tdc">7</td></tr>

-  <tr>

-    <td class="tdl">46 Hastia</td>

-    <td class="tdl">1857, August 16</td>

-    <td class="tdl">Pogson</td>

-    <td class="tdl">Oxford</td>

-    <td class="tdc">3</td></tr>

-  <tr>

-    <td class="tdl">47 Aglaia</td>

-    <td class="tdl">1857, Sept. 15</td>

-    <td class="tdl">Luther</td>

-    <td class="tdl">Bilk</td>

-    <td class="tdc">6</td></tr>

-  <tr>

-    <td class="tdl">48 Doris</td>

-    <td class="tdl">1857, Sept. 19</td>

-    <td class="tdl">Goldschmidt</td>

-    <td class="tdl">Paris</td>

-    <td class="tdc">8</td></tr>

-  <tr>

-    <td class="tdl">49 Pales</td>

-    <td class="tdl">1857, Sept. 19</td>

-    <td class="tdl">Goldschmidt</td>

-    <td class="tdl">Paris</td>

-    <td class="tdc">9</td></tr>

-  <tr>

-    <td class="tdl">50 Virginia</td>

-    <td class="tdl">1857, Oct. 4</td>

-    <td class="tdl">Furguson</td>

-    <td class="tdl">Washington</td>

-    <td class="tdc">2</td></tr>

-  <tr>

-    <td class="tdl">51 Nemausa</td>

-    <td class="tdl">1858, Jan. 22</td>

-    <td class="tdl">Laurent</td>

-    <td class="tdl">Nismes</td>

-    <td class="tdc">1</td></tr>

-  <tr>

-    <td class="tdl">52 Europa</td>

-    <td class="tdl">1858, Feb. 6</td>

-    <td class="tdl">Goldschmidt</td>

-    <td class="tdl">Paris</td>

-    <td class="tdc">10 </td></tr>

-  <tr>

-    <td class="tdl">53 Calypso</td>

-    <td class="tdl">1858, April 8</td>

-    <td class="tdl">Luther</td>

-    <td class="tdl">Bilk</td>

-    <td class="tdc">7</td></tr>

-  <tr>

-    <td class="tdl">54 Alexandra</td>

-    <td class="tdl">1858, Sept. 11</td>

-    <td class="tdl">Goldschmidt</td>

-    <td class="tdl">Paris</td>

-    <td class="tdc">11 </td></tr>

-  <tr>

-    <td class="tdl bb">55 (Not named)</td>

-    <td class="tdl bb">1858, Sept. 11</td>

-    <td class="tdl bb">Searle</td>

-    <td class="tdl bb">Albany</td>

-    <td class="tdc bb">1</td></tr>

-</table>

-

-<p><span class="pagenum"><a name="Page_240" id="Page_240">240</a></span></p>

-

-<h3>THE COMET OF DONATI.</h3>

-

-<p>While this sheet was passing through the press, the attention

-of astronomers, and of the public generally, was drawn to the

-fact of the above Comet passing (on Oct. 18) within nine millions

-of miles of the planet Venus, or less than 9/100ths of the

-earth’s distance from the Sun. “And (says Mr. Hind, the astronomer),

-it is obvious that if the comet had reached its least

-distance from the sun a few days earlier than it has done, the

-planet might have passed through it; and I am very far from

-thinking that close proximity to a comet of this description

-would be unattended with danger. The inhabitants of Venus

-will witness a cometary spectacle far superior to that which

-has recently attracted so much attention here, inasmuch as the

-tail will doubtless appear twice as long from that planet as

-from the earth, and the nucleus proportionally more brilliant.”</p>

-

-<p>This Comet was first discovered by Dr. G.&nbsp;B. Donati, astronomer

-at the Museum of Florence, on the evening of the 2d of

-June, in right ascension 141° 18′, and north declination 23° 47′,

-corresponding to a position near the star Leonis. Previous to

-this date we had no knowledge of its existence, and therefore

-it was not a predicted comet; neither is it the one last observed

-in 1556. At the date of discovery it was distant from

-the earth 228,000,000 of miles, and was an excessively faint object

-in the largest telescopes.</p>

-

-<p>The tail, from October 2 to 16, when the comet was most

-conspicuous, appears to have maintained an average length

-of at least 40,000,000 miles, subtending an angle varying from

-30° to 40°. The dark line or space down the centre, frequently

-remarked in other great comets, was a striking characteristic

-in that of Donati. The nucleus, though small, was

-intensely brilliant in powerful instruments, and for some time

-bore high magnifiers to much greater advantage than is usual

-with these objects. In several respects this comet resembled

-the famous ones of 1744, 1680, and 1811, particularly as regards

-the signs of violent agitation going on in the vicinity of

-the nucleus, such as the appearance of luminous jets, spiral

-offshoots, &amp;c., which rapidly emanated from the planetary point

-and as quickly lost themselves in the general nebulosity of the

-head.</p>

-

-<p>On the 5th Oct. the most casual observer had an opportunity

-of satisfying himself as to the accuracy of the mathematical

-theory of the motions of comets in the near approach of the

-nucleus of Donati’s to Arcturus, the principal star in the constellation

-Bootes. The circumstance of the appulse was very

-nearly as predicted by Mr. Hind.</p>

-

-<p>The comet, according to the investigations by M. Loewy,<span class="pagenum"><a name="Page_241" id="Page_241">241</a></span>

-of the Observatory of Vienna, arrived at its least distance from

-the sun a few minutes after eleven o’clock on the morning of

-the 30th of September; its longitude, as seen from the sun at

-this time, being 36° 13′, and its distance from him 55,000,000

-miles. The longer diameter of its orbit is 184 times that of

-the earth’s, or 35,100,000,000 miles; yet this is considerably

-less than 1/1000th of the distance of the nearest fixed star. As

-an illustration, let any one take a half-sheet of note-paper, and

-marking a circle with a sixpence in one corner of it, describe

-therein our solar system, drawing the orbits of the earth and

-the inferior planets as small as he can by the aid of a magnifying-glass.

-If the circumference of the sixpence stands for the

-orbit of Neptune, then an oval filling the page will fairly represent

-the orbit of Donati’s comet; and if the paper be laid upon

-the pavement under the west door of St. Paul’s Cathedral, London,

-the length of that edifice will inadequately represent the

-distance of the nearest fixed star. The time of revolution resulting

-from Mr. Loewy’s calculations is 2495 years, which is

-about 500 years less than that of the comet of 1811 during the

-period it was visible from the earth.</p>

-

-<p>That the comet should take more than 2000 years to travel

-round the above page of note-paper is explained by its great

-diminution of speed as it recedes from the sun. At its perihelion

-it travelled at the rate of 127,000 miles an hour, or more than

-twice as fast as the earth, whose motion is about 1000 miles a

-minute. At its aphelion, however, or its greatest distance from

-the sun, the comet is a very slow body, sailing at the rate of

-480 miles an hour, or only eight times the speed of a railway

-express. At this pace, were it to travel onward in a straight

-line, the lapse of a million of years would find it still travelling

-half way between our sun and the nearest fixed star.</p>

-

-<p>As this comet last visited us between 2000 and 2495 years

-since, we know that its appearance was at an interesting period

-of the world’s history. It might have terrified the Athenians

-into accepting the bloody code of Draco. It might have announced

-the destruction of Nineveh, or of Babylon, or the

-capture of Jerusalem by Nebuchadnezzar. It might have been

-seen by the expedition which sailed round Africa in the reign

-of Pharaoh Necho. It might have given interest to the foundation

-of the Pythian games. Within the probable range of its

-last visitation are comprehended the whole of the great events

-of the history of Greece; and among the spectators of the comet

-may have been the so-called sages of Greece and even the prophets

-of Holy Writ: Thales might have attempted to calculate

-its return, and Jeremiah might have tried to read its warning.&mdash;<i>Abridged

-from a Communication from Mr. Hind to the Times, and from a Leader

-in that Journal.</i></p>

-

-<p><span class="pagenum"><a name="Page_242" id="Page_242">242</a></span></p>

-

-<div class="chapter"></div>

-<div class="footnotes">

-<h2 class="p0 p1"><a name="FOOTNOTES" id="FOOTNOTES"></a>FOOTNOTES:</h2>

-

-<div class="footnote">

-

-<p class="fn1"><a name="Footnote_1" id="Footnote_1" href="#FNanchor_1" class="fnanchor">1</a> From a photograph, with figures, to show the relative size of the tube aperture.</p></div>

-

-<div class="footnote">

-

-<p class="fn1"><a name="Footnote_2" id="Footnote_2" href="#FNanchor_2" class="fnanchor">2</a> Weld’s <i>History of the Royal Society</i>, vol. ii. p. 188.</p></div>

-

-<div class="footnote">

-

-<p class="fn1"><a name="Footnote_3" id="Footnote_3" href="#FNanchor_3" class="fnanchor">3</a> Dr. Whewell (<i>Bridgewater Treatise</i>, p. 266) well observes, that Boyle and

-Pascal are to hydrostatics what Galileo is to mechanics, and Copernicus, Kepler,

-and Newton are to astronomy.</p></div>

-

-<div class="footnote">

-

-<p class="fn1"><a name="Footnote_4" id="Footnote_4" href="#FNanchor_4" class="fnanchor">4</a> The Rev. Mr. Turnor recollects that Mr. Jones, the tutor, mentioned, in one

-of his lectures on optics, that the reflecting telescope belonging to Newton was

-then lodged in the observatory over the gateway; and Mr. Turnor thinks that

-he once saw it, with a finder affixed to it.</p></div>

-

-<div class="footnote">

-

-<p class="fn1"><a name="Footnote_5" id="Footnote_5" href="#FNanchor_5" class="fnanchor">5</a> The story of the dog “Diamond” having caused the burning of certain

-papers is laid in London, and in Newton’s later years. In the notes to Maude’s

-<i>Wenleysdale</i>, a person then living (1780) relates, that Sir Isaac being called out

-of his study to a contiguous room, a little dog, called Diamond, the constant

-but incurious attendant of his master’s researches, happened to be left among

-the papers, and by a fatality not to be retrieved, as it was in the latter part of

-Sir Isaac’s days, threw down a lighted candle, which consumed the almost

-finished labour of some years. Sir Isaac returning too late but to behold the

-dreadful wreck, rebuked the author of it with an exclamation (<i>ad sidera palmas</i>),

-“O Diamond! Diamond! thou little knowest the mischief done!” without adding

-a single stripe. M. Biot gives this fiction as a true story, which happened

-some years after the publication of the <i>Principia</i>; and he characterises the accident

-as having deprived the sciences forever of the fruit of so much of Newton’s

-labours.&mdash;Brewster’s <i>Life</i>, vol. ii. p. 139, note. Dr. Newton remarks, that Sir

-Isaac never had any communion with dogs or cats; and Sir David Brewster

-adds, that the view which M. Biot has taken of the idle story of the dog Diamond,

-charged with fire-raising among Newton’s manuscripts, and of the influence

-of this accident upon the mind of their author, is utterly incomprehensible.

-The fiction, however, was turned to account in giving colour to M. Biot’s misrepresentation.</p></div>

-

-<div class="footnote">

-

-<p class="fn1"><a name="Footnote_6" id="Footnote_6" href="#FNanchor_6" class="fnanchor">6</a> Bohn’s edition.</p></div>

-

-<div class="footnote">

-

-<p class="fn1"><a name="Footnote_7" id="Footnote_7" href="#FNanchor_7" class="fnanchor">7</a> When at Pisa, many years since, Captain Basil Hall investigated the

-origin and divergence of the tower from the perpendicular, and established

-completely to his own satisfaction that it had been built from top to bottom

-originally just as it now stands. His reasons for thinking so were, that the line

-of the tower, on that side towards which it leans, has not the same curvature as

-the line on the opposite, or what may be called the upper side. If the tower

-had been built upright, and then been made to incline over, the line of the wall

-on that side towards which the inclination was given would be more or less

-concave in that direction, owing to the nodding or “swagging over” of the top,

-by the simple action of gravity acting on a very tall mass of masonry, which is

-more or less elastic when placed in a sloping position. But the contrary is the

-fact; for the line of wall on the side towards which the tower leans is decidedly

-more convex than the opposite side. Captain Hall had therefore no doubt

-whatever that the architect, in rearing his successive courses of stones, gained

-or stole a little at each layer, so as to render his work less and less overhanging

-as he went up; and thus, without betraying what he was about, really gained

-stability.&mdash;See <i>Patchwork</i>.</p></div>

-

-<div class="footnote">

-

-<p class="fn1"><a name="Footnote_8" id="Footnote_8" href="#FNanchor_8" class="fnanchor">8</a> Lord Bacon proposed that, in order to determine whether the gravity of the

-earth arises from the gravity of its parts, a clock-pendulum should be swung in

-a mine, as was recently done at Harton colliery by the Astronomer-Royal.

-</p>

-<p>

-When, in 1812, Ampère noted the phenomena of the pendulum, and showed

-that its movement was produced only when the eye of the observer was fixed

-on the instrument, and endeavoured to prove thereby that the motion was due to

-a play of the muscles, some members of the French Academy objected to the

-consideration of a subject connected to such an extent with superstition.</p></div>

-

-<div class="footnote">

-

-<p class="fn1"><a name="Footnote_9" id="Footnote_9" href="#FNanchor_9" class="fnanchor">9</a> This curious fact was first recorded by Pepys, in his <i>Diary</i>, under the date

-31st of July 1665.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_10" id="Footnote_10" href="#FNanchor_10" class="fnanchor">10</a> The result of these experiments for ascertaining the variation of the gravity

-at great depths, has proved beyond doubt that the attraction of gravitation

-is increased at the depth of 1250 feet by 1/19000 part.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_11" id="Footnote_11" href="#FNanchor_11" class="fnanchor">11</a> See the account of Mr. Baily’s researches (with two illustrations) in <i>Things

-not generally Known</i>, p. vii., and “Weight of the Earth,” p. 16.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_12" id="Footnote_12" href="#FNanchor_12" class="fnanchor">12</a> Fizeau gives his result in leagues, reckoning twenty-five to the equatorial

-degree. He estimates the velocity of light at 70,000 such leagues, or about

-210,000 miles in the second.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_13" id="Footnote_13" href="#FNanchor_13" class="fnanchor">13</a> See <i>Things not generally Known</i>, p. 88.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_14" id="Footnote_14" href="#FNanchor_14" class="fnanchor">14</a> Some time before the first announcement of the discovery of sun-painting,

-the following extract from Sir John Herschel’s <i>Treatise on Light</i>, in the <i>Encyclopædia

-Metropolitana</i>, appeared in a popular work entitled <i>Parlour Magic</i>: “Strain

-a piece of paper or linen upon a wooden frame, and sponge it over with a solution

-of nitrate of silver in water; place it behind a painting upon glass, or a stained

-window-pane, and the light, traversing the painting or figures, will produce a

-copy of it upon the prepared paper or linen; those parts in which the rays were

-least intercepted being the shadows of the picture.”</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_15" id="Footnote_15" href="#FNanchor_15" class="fnanchor">15</a> In his book on Colours, Mr. Doyle informs us that divers, if not all, essential

-oils, as also spirits of wine, when shaken, “have a good store of bubbles,

-which appear adorned with various and lively colours.” He mentions also that

-bubbles of soap and turpentine exhibit the same colours, which “vary according

-to the incidence of the sight and the position of the eye;” and he had seen a

-glass-blower blow bubbles of glass which burst, and displayed “the varying

-colours of the rainbow, which were exceedingly vivid.”</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_16" id="Footnote_16" href="#FNanchor_16" class="fnanchor">16</a> The original idea is even attributed to Copernicus. M. Blundevile, in his

-<i>Treatise on Cosmography</i>, 1594, has the following passage, perhaps the most distinct

-recognition of authority in our language: “How prooue (prove) you that

-there is but one world? By the authoritie of Aristotle, who saieth that if there

-were any other world out of this, then the earth of that world would mooue

-(move) towards the centre of this world,” &amp;c.

-</p>

-<p>

-Sir Isaac Newton, in a conversation with Conduitt, said he took “all the

-planets to be composed of the same matter with the earth, viz. earth, water, and

-stone, but variously concocted.”</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_17" id="Footnote_17" href="#FNanchor_17" class="fnanchor">17</a> Sir William Herschel ascertained that our solar system is advancing towards

-the constellation Hercules, or more accurately to a point in space whose

-right ascension is 245° 52′ 30″, and north polar distance 40° 22′; and that the

-quantity of this motion is such, that to an astronomer placed in Sirius, our sun

-would appear to describe an arc of little more than <i>a second</i> every year.&mdash;<i>North-British

-Review</i>, No. 3.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_18" id="Footnote_18" href="#FNanchor_18" class="fnanchor">18</a> See M. Arago’s researches upon this interesting subject, in <i>Things not generally

-Known</i>, p. 4.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_19" id="Footnote_19" href="#FNanchor_19" class="fnanchor">19</a> This eloquent advocacy of the doctrine of “More Worlds than One” (referred

-to at p. 51) is from the author’s valuable <i>Outlines of Astronomy</i>.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_20" id="Footnote_20" href="#FNanchor_20" class="fnanchor">20</a> Professor Challis, of the Cambridge Observatory, directing the Northumberland

-telescope of that institution to the place assigned by Mr. Adams’s calculations

-and its vicinity on the 4th and 12th of August 1846, saw the planet on

-both those days, and noted its place (among those of other stars) for re-observation.

-He, however, postponed the <i>comparison</i> of the places observed, and not

-possessing Dr. Bremiker’s chart (which would at once have indicated the presence

-of an unmapped star), remained in ignorance of the planet’s existence as a

-visible object till the announcement of such by Dr. Galle.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_21" id="Footnote_21" href="#FNanchor_21" class="fnanchor">21</a> For several interesting details of Comets, see “Destruction of the World

-by a Comet,” in <i>Popular Errors Explained and Illustrated</i>, new edit. pp. 165&ndash;168.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_22" id="Footnote_22" href="#FNanchor_22" class="fnanchor">22</a> The letters of Sir Isaac Newton to Dr. Bentley, containing suggestions for

-the Boyle Lectures, possess a peculiar interest in the present day. “They show”

-(says Sir David Brewster) “that the <i>nebular hypothesis</i>, the dull and dangerous

-heresy of the age, is incompatible with the established laws of the material universe,

-and that an omnipotent arm was required to give the planets their positions

-and motions in space, and a presiding intelligence to assign to them the

-different functions they had to perform.”&mdash;<i>Life of Newton</i>, vol. ii.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_23" id="Footnote_23" href="#FNanchor_23" class="fnanchor">23</a> The constitution of the nebulæ in the constellation of Orion has been resolved

-by this instrument; and by its aid the stars of which it is composed

-burst upon the sight of man for the first time.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_24" id="Footnote_24" href="#FNanchor_24" class="fnanchor">24</a> Several specimens of Meteoric Iron are to be seen in the Mineralogical

-Collection in the British Museum.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_25" id="Footnote_25" href="#FNanchor_25" class="fnanchor">25</a> <i>Life of Sir Isaac Newton</i>, vol. i. p. 62.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_26" id="Footnote_26" href="#FNanchor_26" class="fnanchor">26</a> <i>Description of the Monster Telescope</i>, by Thomas Woods, M.D. 4th edit. 1851.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_27" id="Footnote_27" href="#FNanchor_27" class="fnanchor">27</a> This instrument also discovered a multitude of new objects in the moon;

-as a mountainous tract near Ptolemy, every ridge of which is dotted with extremely

-minute craters, and two black parallel stripes in the bottom of Aristarchus.

-Dr. Robinson, in his address to the British Association in 1843, stated that

-in this telescope a building the size of the Court-house at Cork would be easily

-visible on the lunar surface.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_28" id="Footnote_28" href="#FNanchor_28" class="fnanchor">28</a> Mr. Hopkins supports his Glacial Theory by regarding the <i>Waves of Translation</i>,

-investigated by Mr. Scott Russell, as furnishing a sufficient moving power

-for the transportation of large rounded boulders, and the formation of drifted

-gravel. When these waves of translation are produced by the sudden elevation

-of the surface of the sea, the whole mass of water from the surface to the bottom

-of the ocean moves onward, and becomes a mechanical agent of enormous power.

-Following up this view, Mr. Hopkins has shown that “elevations of continental

-masses of only 50 feet each, and from beneath an ocean having a depth of between

-300 and 400 feet, would cause the most powerful divergent waves, which

-could transport large boulders to great distances.”</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_29" id="Footnote_29" href="#FNanchor_29" class="fnanchor">29</a> It is scarcely too much to say, that from the collection of specimens of

-building-stones made upon this occasion, and first deposited in a house in Craig’s

-Court, Charing Cross, originated, upon the suggestion of Sir Henry Delabeche,

-the magnificent Museum of Practical Geology in Jermyn Street; one of the most

-eminently practical institutions of this scientific age.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_30" id="Footnote_30" href="#FNanchor_30" class="fnanchor">30</a> Mr. R. Mallet, F.R.S., and his son Dr. Mallet, have constructed a seismographic

-map of the world, with seismic bands in their position and relative

-intensity; and small black discs to denote volcanoes, femaroles, and soltataras,

-and shades indicating the areas of subsidence.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_31" id="Footnote_31" href="#FNanchor_31" class="fnanchor">31</a> It has been computed that the shock of this earthquake pervaded an area

-of 700,000 miles, or the twelfth part of the circumference of the globe. This

-dreadful shock lasted only five minutes; and nearly the whole of the population

-being within the churches (on the feast of All Saints), no less than 30,000 persons

-perished by the fall of these edifices.&mdash;See <i>Daubeny on Volcanoes</i>; <i>Translator’s

-note, Humboldt’s Cosmos</i>.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_32" id="Footnote_32" href="#FNanchor_32" class="fnanchor">32</a> Mr. Murray mentions, on the authority of the Rev. Dr. Robinson, of the

-Observatory at Armagh, that a rough diamond with a red tint, and valued by

-Mr. Rundell at twenty guineas, was found in Ireland, many years since, in the

-bed of a brook flowing through the county of Fermanagh.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_33" id="Footnote_33" href="#FNanchor_33" class="fnanchor">33</a> The use of malachite in ornamental work is very extensive in Russia.

-Thus, to the Great Exhibition of 1851 were sent a pair of folding-doors veneered

-with malachite, 13 feet high, valued at 6000<i>l.</i>; malachite cases and pedestals from

-1500<i>l.</i> to 3000<i>l.</i> a-piece, malachite tables 400<i>l.</i>, and chairs 150<i>l.</i> each.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_34" id="Footnote_34" href="#FNanchor_34" class="fnanchor">34</a> Longfellow has written some pleasing lines on “The Fiftieth Birthday of

-M. Agassiz. May 28, 1857,” appended to “The Courtship of Miles Standish,”

-1858.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_35" id="Footnote_35" href="#FNanchor_35" class="fnanchor">35</a> The <i>sloth</i> only deserves its name when it is obliged to attempt to proceed

-along the ground; when it has any thing which it can lay hold of it is agile

-enough.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_36" id="Footnote_36" href="#FNanchor_36" class="fnanchor">36</a> Dr. A. Thomson has communicated to <i>Jameson’s Journal</i>, No. 112, a Description

-of the Caves in the North Island, with some general observations on

-this genus of birds. He concludes them to have been indolent, dull, and stupid;

-to have lived chiefly on vegetable food in mountain fastnesses and secluded

-caverns.

-</p>

-<p>

-In the picture-gallery at Drayton Manor, the seat of Sir Robert Peel, hangs a

-portrait of Professor Owen, and in his hand is depicted the tibia of a Moa.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_37" id="Footnote_37" href="#FNanchor_37" class="fnanchor">37</a> According to the law of correlation, so much insisted on by Cuvier, a superior

-character implies the existence of its inferiors, and that too in definite proportions

-and constant connections; so that we need only the assurance of one

-character, to be able to reconstruct the whole animal. The triumph of this system

-is seen in the reconstruction of extinct animals, as in the above case of the Dinornis,

-accomplished by Professor Owen.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_38" id="Footnote_38" href="#FNanchor_38" class="fnanchor">38</a> Not only at London, but at Paris, Vienna, Berlin, Turin. St. Petersburg,

-and almost every other capital in Europe; at Liege, Caen, Montpellier, Toulouse,

-and several other large towns,&mdash;wherever, in fact, there are not great local obstacles,&mdash;the

-tendency of the wealthier inhabitants to group themselves to the west

-is as strongly marked as in the British metropolis. At Pompeii, and other ancient

-towns, the same thing maybe noticed; and where the local configuration of

-the town necessitates an increase in a different direction, the moment the obstacle

-ceases houses spread towards the west.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_39" id="Footnote_39" href="#FNanchor_39" class="fnanchor">39</a> By far the most complete set of experiments on the Radiation of Heat from

-the Earth’s Surface at Night which have been published since Dr. Wells’s Memoir

-<i>On Dew</i>, are those of Mr. Glaisher, F.R.S., <i>Philos. Trans.</i> for 1847.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_40" id="Footnote_40" href="#FNanchor_40" class="fnanchor">40</a> The author is largely indebted for the illustrations in this new field of

-research to Lieutenant Maury’s valuable work, <i>The Physical Geography of the Sea</i>.

-Sixth edition. Harper, New York; Low, Son, and Co., London.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_41" id="Footnote_41" href="#FNanchor_41" class="fnanchor">41</a> It is the chloride of magnesia which gives that damp sticky feeling to the

-clothes of sailors that are washed or wetted with salt water.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_42" id="Footnote_42" href="#FNanchor_42" class="fnanchor">42</a> This fraction rests on the assumption that the dilatation of the substances

-of which the earth is composed is equal to that of glass, that is to say, 1/18000 for

-1°. Regarding this hypothesis, see Arago, in the <i>Annuaire</i> for 1834, pp. 177&ndash;190.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_43" id="Footnote_43" href="#FNanchor_43" class="fnanchor">43</a> Electricity, traversing excessively rarefied air or vapours, gives out light,

-and doubtless also heat. May not a continual current of electric matter be constantly

-circulating in the sun’s immediate neighbourhood, or traversing the

-planetary spaces, and exerting in the upper regions of its atmosphere those

-phenomena of which, on however diminutive a scale, we have yet an unequivocal

-manifestation in our Aurora Borealis?</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_44" id="Footnote_44" href="#FNanchor_44" class="fnanchor">44</a> Could we by mechanical pressure force water into a solid state, an immense

-quantity of heat would be set free.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_45" id="Footnote_45" href="#FNanchor_45" class="fnanchor">45</a> See Mr. Hunt’s popular work, <i>The Poetry of Science; or, Studies of Physical

-Phenomena of Nature</i>. Third edition, revised and enlarged. Bohn, 1854.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_46" id="Footnote_46" href="#FNanchor_46" class="fnanchor">46</a> Canton was the first who in England verified Dr. Franklin’s idea of the

-similarity of lightning and the electric fluid, July 1752.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_47" id="Footnote_47" href="#FNanchor_47" class="fnanchor">47</a> This is mentioned in <i>Procli Diadochi Paraphrasis Ptolem.</i>, 1635. (Delambre,

-<i>Hist. de l’Astronomie ancienne</i>.)</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_48" id="Footnote_48" href="#FNanchor_48" class="fnanchor">48</a> The first Variation-Compass was constructed, before 1525, by an ingenious

-apothecary of Seville, Felisse Guillen. So earnest were the endeavours to learn

-more exactly the direction of the curves of magnetic declination, that in 1585

-Juan Jayme sailed with Francisco Gali from Manilla to Acapulco, for the sole

-purpose of trying in the Pacific a declination instrument which he had invented.&mdash;<i>Humboldt.</i></p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_49" id="Footnote_49" href="#FNanchor_49" class="fnanchor">49</a> Gilbert was surgeon to Queen Elizabeth and James I., and died in 1603.

-Whewell justly assigns him an important place among the “practical reformers

-of the physical sciences.” He adopted the Copernican doctrine, which Lord Bacon’s

-inferior aptitude for physical research led him to reject.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_50" id="Footnote_50" href="#FNanchor_50" class="fnanchor">50</a> This illustration, it will be seen, does not literally correspond with the

-details which precede it.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_51" id="Footnote_51" href="#FNanchor_51" class="fnanchor">51</a> Mr. Crosse gave to the meeting a general invitation to Fyne Court; one of

-the first to accept which was Sir Richard Phillips, who, on his return to Brighton,

-described in a very attractive manner, at the Sussex Institution, Mr. Crosse’s

-experiments and apparatus; a report of which being communicated to the

-<i>Brighton Herald</i>, was quoted in the <i>Literary Gazette</i>, and thence copied generally

-into the newspapers of the day.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_52" id="Footnote_52" href="#FNanchor_52" class="fnanchor">52</a> These experiments were performed at the expense of the Royal Society, and

-cost 10<i>l.</i> 5<i>s.</i> 6<i>d.</i> In the Paper detailing the experiments, printed in the 45th

-volume of the <i>Philosophical Transactions</i>, occurs the first mention of Dr. Franklin’s

-name, and of his theory of positive and negative electricity.&mdash;<i>Weld’s Hist. Royal

-Soc.</i> vol. i. p. 467.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_53" id="Footnote_53" href="#FNanchor_53" class="fnanchor">53</a> In this year Andrew Crosse said: “I prophesy that by means of the electric

-agency we shall be enabled to communicate our thoughts instantaneously with

-the uttermost parts of the earth.”</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_54" id="Footnote_54" href="#FNanchor_54" class="fnanchor">54</a> To which paper the writer is indebted for many of these details.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_55" id="Footnote_55" href="#FNanchor_55" class="fnanchor">55</a> These illustrations have been in the main selected and abridged from papers

-in the <i>Companion to the Almanac</i>, 1858, and the <i>Penny Cyclopædia</i>, 2d supp.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_56" id="Footnote_56" href="#FNanchor_56" class="fnanchor">56</a> Newton was, however, much pestered with inquirers; and a Correspondent

-of the <i>Gentleman’s Magazine</i>, in 1784, relates that he once had a transient view of

-a Ms. in Pope’s handwriting, in which he read a verified anecdote relating to the

-above period. Sir Isaac being often interrupted by ignorant pretenders to the

-discovery of the longitude, ordered his porter to inquire of every stranger who

-desired admission whether he came about the longitude, and to exclude such as

-answered in the affirmative. Two lines in Pope’s Ms., as the Correspondent recollects,

-ran thus:

-</p>

-

-<div class="poem-container">

-<div class="poem"><div class="stanza">

-<span class="iq">“‘Is it about the longitude you come?’<br /></span>

-<span class="i0">The porter asks: ‘Sir Isaac’s not at home.’”<br /></span>

-</div></div>

-</div>

-</div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_57" id="Footnote_57" href="#FNanchor_57" class="fnanchor">57</a> In trying the merits of Harrison’s chronometers, Dr. Maskelyne acquired

-that knowledge of the wants of nautical astronomy which afterwards led to the

-formation of the Nautical Almanac.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_58" id="Footnote_58" href="#FNanchor_58" class="fnanchor">58</a> A slight electric shock is given to a man at a certain portion of the skin;

-and he is directed the moment he feels the stroke to make a certain motion, as

-quickly as he possibly can, with the hands or with the teeth, by which the time-measuring

-current is interrupted.</p></div>

-

-<div class="footnote">

-

-<p class="fn2"><a name="Footnote_59" id="Footnote_59" href="#FNanchor_59" class="fnanchor">59</a> Through the calculations of M. Le Verrier.</p></div>

-</div>

-

-<div class="chapter"></div>

-<h2><a name="GENERAL_INDEX" id="GENERAL_INDEX"></a>GENERAL INDEX</h2>

-

-<div class="index">

-<ul class="index"><li class="ifrst">Abodes of the Blest, <a href="#Page_58">58</a>.</li>

-

-<li class="indx">Acarus of Crosse and Weeks, <a href="#Page_218">218</a>.</li>

-

-<li class="indx">Accuracy of Chinese Observers, <a href="#Page_159">159</a>.</li>

-

-<li class="indx">Adamant, What was it?, <a href="#Page_123">123</a>.</li>

-

-<li class="indx">Aeronautic Voyage, Remarkable, <a href="#Page_169">169</a>.</li>

-

-<li class="indx">Agassiz, Discoveries of, <a href="#Page_127">127</a>.</li>

-

-<li class="indx">Air, Weight of, <a href="#Page_14">14</a>.</li>

-

-<li class="indx">All the World in Motion, <a href="#Page_11">11</a>.</li>

-

-<li class="indx">Alluvial Land of Egypt, <a href="#Page_110">110</a>.</li>

-

-<li class="indx">Ancient World, Science of the, <a href="#Page_1">1</a>.</li>

-

-<li class="indx">Animals in Geological Times, <a href="#Page_128">128</a>.</li>

-

-<li class="indx">Anticipations of the Electric Telegraph, <a href="#Page_220">220&ndash;224</a>.</li>

-

-<li class="indx">Arago on Protection from Storms, <a href="#Page_159">159</a>.</li>

-

-<li class="indx">Arctic Climate, Phenomena of, <a href="#Page_162">162</a>.</li>

-

-<li class="indx">Arctic Explorations, Rae’s, <a href="#Page_162">162</a>.</li>

-

-<li class="indx">Arctic Regions, Scenery and Life of, <a href="#Page_180">180</a>.</li>

-

-<li class="indx">Arctic Temperature, <a href="#Page_161">161</a>.</li>

-

-<li class="indx">Armagh Observatory Level, Change of, <a href="#Page_144">144</a>.</li>

-

-<li class="indx">Artesian Fire-Springs, <a href="#Page_118">118</a>.</li>

-

-<li class="indx">Artesian Well of Grenelle, <a href="#Page_114">114</a>.</li>

-

-<li class="indx">Astronomer, Peasant, <a href="#Page_101">101</a>.</li>

-

-<li class="indx">Astronomer’s Dream verified, <a href="#Page_88">88</a>.</li>

-

-<li class="indx">Astronomers, Triad of Contemporary, <a href="#Page_100">100</a>.</li>

-

-<li class="indx">Astronomical Observations, Nicety of, <a href="#Page_102">102</a>.</li>

-

-<li class="indx">Astronomy and Dates on Monuments, <a href="#Page_55">55</a>.</li>

-

-<li class="indx">Astronomy and Geology, Identity of, <a href="#Page_104">104</a>.</li>

-

-<li class="indx">Astronomy, Great Truths of, <a href="#Page_54">54</a>.</li>

-

-<li class="indx">Atheism, Folly of, <a href="#Page_3">3</a>.</li>

-

-<li class="indx">Atlantic, Basin of the, <a href="#Page_171">171</a>.</li>

-

-<li class="indx">Atlantic, Gales of the, <a href="#Page_171">171</a>.</li>

-

-<li class="indx">Atlantic Telegraph, the, <a href="#Page_226">226&ndash;228</a>.</li>

-

-<li class="indx">Atmosphere, Colours of the, <a href="#Page_147">147</a>.</li>

-

-<li class="indx">Atmosphere compared to a Steam-engine, <a href="#Page_152">152</a>.</li>

-

-<li class="indx">Atmosphere, Height of, <a href="#Page_147">147</a>.</li>

-

-<li class="indx">Atmosphere, the, <a href="#Page_146">146</a>.</li>

-

-<li class="indx">Atmosphere, the purest, <a href="#Page_150">150</a>.</li>

-

-<li class="indx">Atmosphere, Universality of the, <a href="#Page_147">147</a>.</li>

-

-<li class="indx">Atmosphere weighed by Pascal, <a href="#Page_148">148</a>.</li>

-

-<li class="indx">Atoms of Elementary Bodies, <a href="#Page_13">13</a>.</li>

-

-<li class="indx">Atoms, the World of, <a href="#Page_13">13</a>.</li>

-

-<li class="indx">Aurora Borealis, Halley’s hypothesis of, <a href="#Page_198">198</a>.</li>

-

-<li class="indx">Aurora Borealis, Splendour of the, <a href="#Page_165">165</a>.</li>

-

-<li class="indx">Australian Cavern, Inmates of, <a href="#Page_137">137</a>.</li>

-

-<li class="indx">Australian Pouch-Lion, <a href="#Page_137">137</a>.</li>

-

-<li class="indx">Axis of Rotation, the, <a href="#Page_11">11</a>.</li>

-

-<li class="ifrst">Barometer, Gigantic, <a href="#Page_151">151</a>.</li>

-

-<li class="indx">Barometric Measurement, <a href="#Page_151">151</a>.</li>

-

-<li class="indx">Batteries, Minute and Vast, <a href="#Page_204">204</a>.</li>

-

-<li class="indx">Birds, Gigantic, of New Zealand, Extinct, <a href="#Page_139">139</a>.</li>

-

-<li class="indx">“Black Waters, the,” <a href="#Page_182">182</a>.</li>

-

-<li class="indx">Bodies, Bright, the Smallest, <a href="#Page_31">31</a>.</li>

-

-<li class="indx">Bodies, Compression of, <a href="#Page_12">12</a>.</li>

-

-<li class="indx">Bodies, Fall of, <a href="#Page_16">16</a>.</li>

-

-<li class="indx">Bottles and Currents at Sea, <a href="#Page_172">172</a>.</li>

-

-<li class="indx">Boulders, How transported to Great Heights, <a href="#Page_105">105</a>.</li>

-

-<li class="indx">Boyle on Colours, <a href="#Page_49">49</a>.</li>

-

-<li class="indx">Boyle, Researches of, <a href="#Page_6">6</a>.</li>

-

-<li class="indx">Brain, Impressions transmitted to, <a href="#Page_235">235</a>.</li>

-

-<li class="indx">Buckland, Dr., his Geological Labours, <a href="#Page_127">127</a>.</li>

-

-<li class="indx">Building-Stone, Wear of, <a href="#Page_108">108</a>.</li>

-

-<li class="indx">Burnet’s Theory of the Earth, <a href="#Page_125">125</a>.</li>

-

-<li class="indx">Bust, Magic, <a href="#Page_36">36</a>.</li>

-

-<li class="ifrst">Candle-flame, Nature of, <a href="#Page_237">237</a>.</li>

-

-<li class="indx">Canton’s Artificial Magnets, <a href="#Page_196">196</a>.</li>

-

-<li class="indx">Carnivora of Britain, Extinct, <a href="#Page_132">132</a>.</li>

-

-<li class="indx">Carnivores, Monster, of France, <a href="#Page_138">138</a>.</li>

-

-<li class="indx">Cataract, Great, in India, <a href="#Page_183">183</a>.<span class="pagenum"><a name="Page_243" id="Page_243">243</a></span></li>

-

-<li class="indx">Cat, Can it see in the Dark?, <a href="#Page_51">51</a>.</li>

-

-<li class="indx">Caves of New Zealand and its Gigantic Birds, <a href="#Page_140">140</a>.</li>

-

-<li class="indx">Cave Tiger or Lion of Britain, <a href="#Page_133">133</a>.</li>

-

-<li class="indx">Central Heat, Theory of, <a href="#Page_116">116</a>.</li>

-

-<li class="indx">Chabert, “the Fire King,” <a href="#Page_192">192</a>.</li>

-

-<li class="indx">Chalk Formation, the, <a href="#Page_108">108</a>.</li>

-

-<li class="indx">Changes on the Earth’s Surface, <a href="#Page_142">142</a>.</li>

-

-<li class="indx">Chantrey, Heat-Experiments by, <a href="#Page_192">192</a>.</li>

-

-<li class="indx">Children’s powerful Battery, <a href="#Page_204">204</a>.</li>

-

-<li class="indx">Chinese, the, and the Magnetic Needle, <a href="#Page_194">194</a>.</li>

-

-<li class="indx">Chronometers, Marine, How rated at Greenwich Observatory, <a href="#Page_229">229</a>.</li>

-

-<li class="indx">Climate, finest in the World, <a href="#Page_149">149</a>.</li>

-

-<li class="indx">Climate, Variations of, <a href="#Page_148">148</a>.</li>

-

-<li class="indx">Climates, Average, <a href="#Page_149">149</a>.</li>

-

-<li class="indx">Clock, How to make Electric, <a href="#Page_212">212</a>.</li>

-

-<li class="indx">Cloud-ring, the Equatorial, <a href="#Page_156">156</a>.</li>

-

-<li class="indx">Clouds, Fertilisation of, <a href="#Page_151">151</a>.</li>

-

-<li class="indx">Coal, Torbane-Hill, <a href="#Page_123">123</a>.</li>

-

-<li class="indx">Coal, What is it?, <a href="#Page_123">123</a>.</li>

-

-<li class="indx">Cold in Hudson’s Bay, <a href="#Page_160">160</a>.</li>

-

-<li class="indx">Colour of a Body, and its Magnetic Properties, <a href="#Page_197">197</a>.</li>

-

-<li class="indx">Colours and Tints, Chevreul on, <a href="#Page_37">37</a>.</li>

-

-<li class="indx">Colours most frequently hit in Battle, <a href="#Page_36">36</a>.</li>

-

-<li class="indx">Comet, the, of Donati, <a href="#Page_240">240</a>, <a href="#Page_241">241</a>.</li>

-

-<li class="indx">Comet, Great, of 1843, <a href="#Page_84">84</a>.</li>

-

-<li class="indx">Comets, Magnitude of, <a href="#Page_84">84</a>.</li>

-

-<li class="indx">Comets visible in Sunshine, <a href="#Page_84">84</a>.</li>

-

-<li class="indx">Computation, Power of, <a href="#Page_10">10</a>.</li>

-

-<li class="indx">Coney of Scripture, <a href="#Page_137">137</a>.</li>

-

-<li class="indx">Conic Sections, <a href="#Page_10">10</a>.</li>

-

-<li class="indx">Continent Outlines not fixed, <a href="#Page_145">145</a>.</li>

-

-<li class="indx">Corpse, How soon it decays, <a href="#Page_237">237</a>.</li>

-

-<li class="indx">“Cosmos, Science of the,” <a href="#Page_10">10</a>.</li>

-

-<li class="indx">Crosse, Andrew, his Artificial Crystals and Minerals, <a href="#Page_216">216&ndash;219</a>.</li>

-

-<li class="indx">Crosse Mite, the, <a href="#Page_218">218</a>.</li>

-

-<li class="indx">Crystallisation, Reproductive, <a href="#Page_26">26</a>.</li>

-

-<li class="indx">Crystallisation, Theory of, <a href="#Page_24">24</a>.</li>

-

-<li class="indx">Crystallisation, Visible, <a href="#Page_25">25</a>.</li>

-

-<li class="indx">Crystals, Immense, <a href="#Page_24">24</a>.</li>

-

-<li class="indx">“Crystal Vault of Heaven,” <a href="#Page_55">55</a>.</li>

-

-<li class="ifrst">Davy, Sir Humphry, obtains Heat from Ice, <a href="#Page_190">190</a>.</li>

-

-<li class="indx">Davy’s great Battery at the Royal Institution, <a href="#Page_204">204</a>.</li>

-

-<li class="indx">Day, Length of, and Heat of the Earth, <a href="#Page_186">186</a>.</li>

-

-<li class="indx">Day’s Length at the Poles, <a href="#Page_65">65</a>.</li>

-

-<li class="indx">Declination of the Needle, <a href="#Page_197">197</a>.</li>

-

-<li class="indx">Descartes’ Labours in Physics, <a href="#Page_9">9</a>.</li>

-

-<li class="indx">Desert, Intense Heat and Cold of the, <a href="#Page_163">163</a>.</li>

-

-<li class="indx">Dew-drop, Beauty of the, <a href="#Page_157">157</a>.</li>

-

-<li class="indx">Dew-fall in one year, <a href="#Page_157">157</a>.</li>

-

-<li class="indx">Dew graduated to supply Vegetation, <a href="#Page_157">157</a>.</li>

-

-<li class="indx">Diamond, Geological Age of, <a href="#Page_122">122</a>.</li>

-

-<li class="indx">Diamond Lenses for Microscopes, <a href="#Page_40">40</a>.</li>

-

-<li class="indx">“Diamond,” Newton’s Dog, <a href="#Page_8">8</a>.</li>

-

-<li class="indx">Dinornis elephantopus, the, <a href="#Page_139">139</a>, <a href="#Page_140">140</a>.</li>

-

-<li class="indx">Dinotherium, or Terrible Beast, the, <a href="#Page_136">136</a>.</li>

-

-<li class="indx">Diorama, Illusion of the, <a href="#Page_37">37</a>.</li>

-

-<li class="ifrst">Earth and Man compared, <a href="#Page_22">22</a>.</li>

-

-<li class="indx">Earth, Figure of the, <a href="#Page_21">21</a>.</li>

-

-<li class="indx">Earth, Mass and Density of, <a href="#Page_21">21</a>.</li>

-

-<li class="indx">Earth’s Annual Motion, <a href="#Page_12">12</a>.</li>

-

-<li class="indx">Earth’s Magnitude, to ascertain, <a href="#Page_21">21</a>.</li>

-

-<li class="indx">Earth’s Surface, Mean Temperature of, <a href="#Page_23">23</a>.</li>

-

-<li class="indx">Earth’s Temperature, Interior, <a href="#Page_116">116</a>.</li>

-

-<li class="indx">Earth’s Temperature Stationary, <a href="#Page_23">23</a>.</li>

-

-<li class="indx">Earth, the, a Magnet, <a href="#Page_197">197</a>.</li>

-

-<li class="indx">Earthquake, the Great Lisbon, <a href="#Page_121">121</a>.</li>

-

-<li class="indx">Earthquakes and the Moon, <a href="#Page_121">121</a>.</li>

-

-<li class="indx">Earthquakes, Rumblings of, <a href="#Page_120">120</a>.</li>

-

-<li class="indx">Earthquake-Shock, How to measure, <a href="#Page_120">120</a>.</li>

-

-<li class="indx">Earth-Waves, <a href="#Page_119">119</a>.</li>

-

-<li class="indx">Eclipses, Cause of, <a href="#Page_74">74</a>.</li>

-

-<li class="indx">Egypt, Alluvial Land of, <a href="#Page_110">110</a>.</li>

-

-<li class="indx">Electric Girdle for the Earth, <a href="#Page_224">224</a>.</li>

-

-<li class="indx">Electric Incandescence of Charcoal Points, <a href="#Page_204">204</a>.</li>

-

-<li class="indx">Electric Knowledge, Germs of, <a href="#Page_207">207</a>.</li>

-

-<li class="indx">Electric Light, Velocity of, <a href="#Page_209">209</a>.</li>

-

-<li class="indx">Electric Messages, Time lost in, <a href="#Page_225">225</a>.</li>

-

-<li class="indx">Electric Paper, <a href="#Page_209">209</a>.</li>

-

-<li class="indx">Electric Spark, Duration of, <a href="#Page_209">209</a>.</li>

-

-<li class="indx">Electric Telegraph, Anticipations of the, <a href="#Page_220">220&ndash;224</a>.</li>

-

-<li class="indx">Electric Telegraph, Consumption of, <a href="#Page_224">224</a>.</li>

-

-<li class="indx">Electric Telegraph in Astronomy and Longitude, <a href="#Page_225">225</a>.<span class="pagenum"><a name="Page_244" id="Page_244">244</a></span></li>

-

-<li class="indx">Electric Telegraph and Lightning, <a href="#Page_226">226</a>.</li>

-

-<li class="indx">Electric and Magnetic Attraction, Identity of, <a href="#Page_210">210</a>.</li>

-

-<li class="indx">Electrical Kite, Franklin’s, <a href="#Page_213">213</a>.</li>

-

-<li class="indx">Electricity and Temperature, <a href="#Page_208">208</a>.</li>

-

-<li class="indx">Electricity in Brewing, <a href="#Page_209">209</a>.</li>

-

-<li class="indx">Electricity, Vast Arrangement of, <a href="#Page_208">208</a>.</li>

-

-<li class="indx">Electricity, Water decomposed by, <a href="#Page_208">208</a>.</li>

-

-<li class="indx">Electricities, the Two, <a href="#Page_214">214</a>.</li>

-

-<li class="indx">Electro-magnetic Clock, Wheatstone’s, <a href="#Page_211">211</a>.</li>

-

-<li class="indx">Electro-magnetic Engine, Theory of, <a href="#Page_210">210</a>.</li>

-

-<li class="indx">Electro-magnets, Horse-shoe, <a href="#Page_199">199</a>.</li>

-

-<li class="indx">Electro-telegraphic Message to the Stars, <a href="#Page_226">226</a>.</li>

-

-<li class="indx">Elephant and Tortoise of India, <a href="#Page_135">135</a>.</li>

-

-<li class="indx">End of our System, <a href="#Page_92">92</a>.</li>

-

-<li class="indx">England in the Eocene Period, <a href="#Page_129">129</a>.</li>

-

-<li class="indx">English Channel, Probable Origin of, <a href="#Page_105">105</a>.</li>

-

-<li class="indx">Eocene Period, the, <a href="#Page_129">129</a>.</li>

-

-<li class="indx">Equatorial Cloud-ring, <a href="#Page_156">156</a>.</li>

-

-<li class="indx">“Equatorial Doldrums,” <a href="#Page_156">156</a>.</li>

-

-<li class="indx">Error upon Error, <a href="#Page_185">185</a>.</li>

-

-<li class="indx">Exhilaration in ascending Mountains, <a href="#Page_163">163</a>.</li>

-

-<li class="indx">Eye and Brain seen through a Microscope, <a href="#Page_41">41</a>.</li>

-

-<li class="indx">Eye, interior, Exploration of, <a href="#Page_236">236</a>.</li>

-

-<li class="ifrst">Fall of Bodies, Rate of, <a href="#Page_16">16</a>.</li>

-

-<li class="indx">Falls, Height of, <a href="#Page_16">16</a>.</li>

-

-<li class="indx">Faraday, Genius and Character of, <a href="#Page_193">193</a>.</li>

-

-<li class="indx">Faraday’s Electrical Illustrations, <a href="#Page_214">214</a>.</li>

-

-<li class="indx">“Father of English Geology, the,” <a href="#Page_126">126</a>.</li>

-

-<li class="indx">Fertilisation of Clouds, <a href="#Page_151">151</a>.</li>

-

-<li class="indx">Fire, Perpetual, <a href="#Page_117">117</a>.</li>

-

-<li class="indx">Fire-balls and Shooting Stars, <a href="#Page_89">89</a>.</li>

-

-<li class="indx">Fire-Springs, Artesian, <a href="#Page_118">118</a>.</li>

-

-<li class="indx">Fishes, the most Ancient, <a href="#Page_132">132</a>.</li>

-

-<li class="indx">Flying Dragon, the, <a href="#Page_130">130</a>.</li>

-

-<li class="indx">Force neither created nor destroyed, <a href="#Page_18">18</a>.</li>

-

-<li class="indx">Force of Running Water, <a href="#Page_114">114</a>.</li>

-

-<li class="indx">Fossil Human Bones, <a href="#Page_131">131</a>.</li>

-

-<li class="indx">Fossil Meteoric Stones, none, <a href="#Page_92">92</a>.</li>

-

-<li class="indx">Fossil Rose, none, <a href="#Page_142">142</a>.</li>

-

-<li class="indx">Foucault’s Pendulum Experiments, <a href="#Page_22">22</a>.</li>

-

-<li class="indx">Franklin’s Electrical Kite, <a href="#Page_213">213</a>.</li>

-

-<li class="indx">Freezing Cavern in Russia, <a href="#Page_115">115</a>.</li>

-

-<li class="indx">Fresh Water in Mid-Ocean, <a href="#Page_182">182</a>.</li>

-

-<li class="ifrst">Galilean Telescope, the, <a href="#Page_93">93</a>.</li>

-

-<li class="indx">Galileo, What he first saw with the Telescope, <a href="#Page_93">93</a>.</li>

-

-<li class="indx">Galvani and Volta, <a href="#Page_205">205</a>.</li>

-

-<li class="indx">Galvanic Effects, Familiar, <a href="#Page_203">203</a>.</li>

-

-<li class="indx">Galvanic Waves on the same Wire, Non-interference of, <a href="#Page_225">225</a>.</li>

-

-<li class="indx">“Gauging the Heavens,” <a href="#Page_58">58</a>.</li>

-

-<li class="indx">Genius, Relics of, <a href="#Page_5">5</a>.</li>

-

-<li class="indx">Geology and Astronomy, Identity of, <a href="#Page_104">104</a>.</li>

-

-<li class="indx">Geology of England, <a href="#Page_105">105</a>.</li>

-

-<li class="indx">Geological Time, <a href="#Page_143">143</a>.</li>

-

-<li class="indx">George III., His patronage of Herschel, <a href="#Page_95">95</a>.</li>

-

-<li class="indx">Gilbert on Magnetic and Electric forces, <a href="#Page_201">201</a>.</li>

-

-<li class="indx">Glacial Theory, by Hopkins, <a href="#Page_105">105</a>.</li>

-

-<li class="indx">Glaciers, Antiquity of, <a href="#Page_109">109</a>.</li>

-

-<li class="indx">Glaciers, Phenomena of, Illustrated, <a href="#Page_108">108</a>.</li>

-

-<li class="indx">Glass, Benefits of, to Man, <a href="#Page_92">92</a>.</li>

-

-<li class="indx">Glass broken by Sand, <a href="#Page_26">26</a>.</li>

-

-<li class="indx">Glyptodon, the, <a href="#Page_137">137</a>.</li>

-

-<li class="indx">Gold, Lumps of, in Siberia, <a href="#Page_124">124</a>.</li>

-

-<li class="indx">Greenwich Observatory, Chronometers rated at, <a href="#Page_229">229&ndash;232</a>.</li>

-

-<li class="indx">Grotto del Cane, the, <a href="#Page_112">112</a>.</li>

-

-<li class="indx">Gulf-Stream and the Temperature of London, <a href="#Page_115">115</a>.</li>

-

-<li class="indx">Gunpowder-Magazines, Danger to, <a href="#Page_216">216</a>.</li>

-

-<li class="indx">Gymnotus and the Voltaic Battery, <a href="#Page_206">206</a>.</li>

-

-<li class="indx">Gyroscope, Foucault’s, <a href="#Page_22">22</a>.</li>

-

-<li class="ifrst">Hail and Storms, Protection against, <a href="#Page_159">159</a>.</li>

-

-<li class="indx">Hail-storm, Terrific, <a href="#Page_160">160</a>.</li>

-

-<li class="indx">Hair, Microscopical Examination of, <a href="#Page_41">41</a>.</li>

-

-<li class="indx">Harrison’s Prize Chronometers, <a href="#Page_229">229&ndash;232</a>.</li>

-

-<li class="indx">Heat and Evaporation, <a href="#Page_188">188</a>.</li>

-

-<li class="indx">Heat and Mechanical Power, <a href="#Page_188">188</a>.</li>

-

-<li class="indx">Heat by Friction, <a href="#Page_189">189</a>.</li>

-

-<li class="indx">Heat, Distinctions of, <a href="#Page_187">187</a>.</li>

-

-<li class="indx">Heat, Expenditure of, by the Sun, <a href="#Page_186">186</a>.<span class="pagenum"><a name="Page_245" id="Page_245">245</a></span></li>

-

-<li class="indx">Heat from Gas-lighting, <a href="#Page_189">189</a>.</li>

-

-<li class="indx">Heat from Wood and Ice, <a href="#Page_190">190</a>.</li>

-

-<li class="indx">Heat, Intense, Protection from, <a href="#Page_191">191</a>, <a href="#Page_192">192</a>.</li>

-

-<li class="indx">Heat, Latent, <a href="#Page_187">187</a>.</li>

-

-<li class="indx">Heat of Mines, <a href="#Page_188">188</a>.</li>

-

-<li class="indx">Heat, Nice Measurement of, <a href="#Page_186">186</a>.</li>

-

-<li class="indx">Heat, Origin of, in our System, <a href="#Page_87">87</a>.</li>

-

-<li class="indx">Heat passing through Glass, <a href="#Page_189">189</a>.</li>

-

-<li class="indx">Heat, Repulsion by, <a href="#Page_191">191</a>.</li>

-

-<li class="indx">Heated Metals, Vibration of, <a href="#Page_188">188</a>.</li>

-

-<li class="indx">Heavy Persons, Lifting, <a href="#Page_17">17</a>.</li>

-

-<li class="indx">Heights and Distances, to Calculate, <a href="#Page_19">19</a>.</li>

-

-<li class="indx">Herschel’s Telescopes at Slough, <a href="#Page_95">95</a>.</li>

-

-<li class="indx">Highton’s Minute Battery, <a href="#Page_204">204</a>.</li>

-

-<li class="indx">Hippopotamus of Britain, <a href="#Page_135">135</a>.</li>

-

-<li class="indx">“Horse Latitudes, the,” <a href="#Page_173">173</a>.</li>

-

-<li class="indx">Horse, Three-hoofed, <a href="#Page_138">138</a>.</li>

-

-<li class="indx">Hour-glass, Sand in the, <a href="#Page_20">20</a>.</li>

-

-<li class="ifrst">Ice, Heat from, <a href="#Page_190">190</a>.</li>

-

-<li class="indx">Ice, Warming with, <a href="#Page_190">190</a>.</li>

-

-<li class="indx">Icebergs of the Polar Seas, <a href="#Page_180">180</a>.</li>

-

-<li class="indx">Iguanodon, Food of the, <a href="#Page_129">129</a>.</li>

-

-<li class="indx">Improvement, Perpetuity of, <a href="#Page_5">5</a>.</li>

-

-<li class="indx">Inertia Illustrated, <a href="#Page_14">14</a>.</li>

-

-<li class="ifrst">Jerusalem, Temple of, How protected from Lightning, <a href="#Page_167">167</a>.</li>

-

-<li class="indx">Jew’s Harp, Theory of the, <a href="#Page_29">29</a>.</li>

-

-<li class="indx">Jupiter’s Satellites, Discovery of, <a href="#Page_80">80</a>.</li>

-

-<li class="ifrst">Kaleidoscope, Sir David Brewster’s, <a href="#Page_43">43</a>.</li>

-

-<li class="indx">Kaleidoscope, the, thought to be anticipated, <a href="#Page_43">43</a>.</li>

-

-<li class="indx">Kircher’s “Magnetism,” <a href="#Page_194">194</a>.</li>

-

-<li class="ifrst">Leaning Tower, Stability of, <a href="#Page_15">15</a>.</li>

-

-<li class="indx">Level, Curious Change of, <a href="#Page_144">144</a>.</li>

-

-<li class="indx">Leyden Jar, Origin of the, <a href="#Page_216">216</a>.</li>

-

-<li class="indx">Lifting Heavy Persons, <a href="#Page_17">17</a>.</li>

-

-<li class="indx">Light, Action of, on Muscular Fibres, <a href="#Page_34">34</a>.</li>

-

-<li class="indx">Light, Apparatus for Measuring, <a href="#Page_32">32</a>.</li>

-

-<li class="indx">Light from Buttons, <a href="#Page_36">36</a>.</li>

-

-<li class="indx">Light, Effect of, on the Magnet, <a href="#Page_198">198</a>.</li>

-

-<li class="indx">Light from Fungus, <a href="#Page_36">36</a>.</li>

-

-<li class="indx">Light from the Juice of a Plant, <a href="#Page_35">35</a>.</li>

-

-<li class="indx">Light, Importance of, <a href="#Page_34">34</a>.</li>

-

-<li class="indx">Light, Minuteness of, <a href="#Page_34">34</a>.</li>

-

-<li class="indx">Light Nights, <a href="#Page_35">35</a>.</li>

-

-<li class="indx">Light, Polarisation of, <a href="#Page_33">33</a>.</li>

-

-<li class="indx">Light, Solar and Artificial Compared, <a href="#Page_29">29</a>.</li>

-

-<li class="indx">Light, Source of, <a href="#Page_29">29</a>.</li>

-

-<li class="indx">Light, Undulatory Scale of, <a href="#Page_30">30</a>.</li>

-

-<li class="indx">Light, Velocity of, <a href="#Page_31">31</a>.</li>

-

-<li class="indx">Light, Velocity of, Measured by Fizeau, <a href="#Page_32">32</a>.</li>

-

-<li class="indx">Light from Quartz, <a href="#Page_51">51</a>.</li>

-

-<li class="indx">Lightning-Conductor, Ancient, <a href="#Page_167">167</a>.</li>

-

-<li class="indx">Lightning-Conductors, Service of, <a href="#Page_166">166</a>.</li>

-

-<li class="indx">Lightning Experiment, Fatal, <a href="#Page_214">214</a>.</li>

-

-<li class="indx">Lightning, Photographic Effects of, <a href="#Page_45">45</a>.</li>

-

-<li class="indx">Lightning produced by Rain, <a href="#Page_166">166</a>.</li>

-

-<li class="indx">Lightning, Sheet, What is it?, <a href="#Page_165">165</a>.</li>

-

-<li class="indx">Lightning, Varieties of, <a href="#Page_165">165</a>.</li>

-

-<li class="indx">Lightning, Various Effects of, <a href="#Page_168">168</a>.</li>

-

-<li class="indx">Log, Invention of the, <a href="#Page_173">173</a>.</li>

-

-<li class="indx">London Monument used as an Observatory, <a href="#Page_103">103</a>.</li>

-

-<li class="ifrst">“Maestricht Saurian Fossil,” the, <a href="#Page_141">141</a>.</li>

-

-<li class="indx">Magnet, Power of a, <a href="#Page_195">195</a>.</li>

-

-<li class="indx">Magnets, Artificial, How made, <a href="#Page_195">195</a>.</li>

-

-<li class="indx">Magnetic Clock and Watch, <a href="#Page_211">211</a>.</li>

-

-<li class="indx">Magnetic Electricity discovered, <a href="#Page_199">199</a>.</li>

-

-<li class="indx">Magnetic Hypotheses, <a href="#Page_193">193</a>.</li>

-

-<li class="indx">Magnetic Needle and the Chinese, <a href="#Page_194">194</a>.</li>

-

-<li class="indx">Magnetic Poles, North and South, <a href="#Page_201">201</a>.</li>

-

-<li class="indx">Magnetic Storms, <a href="#Page_202">202</a>.</li>

-

-<li class="indx">“Magnetism,” Kircher’s, <a href="#Page_194">194</a>.</li>

-

-<li class="indx">Malachite, How formed, <a href="#Page_124">124</a>.</li>

-

-<li class="indx">Mammalia in Secondary Rocks, <a href="#Page_130">130</a>.</li>

-

-<li class="indx">Mammoth of the British Isles, <a href="#Page_133">133</a>.</li>

-

-<li class="indx">Mammoth, Remains of the, <a href="#Page_134">134</a>.</li>

-

-<li class="indx">Mars, the Planet, Is it inhabited?, <a href="#Page_82">82</a>.</li>

-

-<li class="indx">Mastodon coexistent with Man, <a href="#Page_135">135</a>.</li>

-

-<li class="indx">Matter, Divisibility of, <a href="#Page_14">14</a>.</li>

-

-<li class="indx">Maury’s Physical Geography of the Sea, <a href="#Page_170">170</a>.</li>

-

-<li class="indx">Mediterranean, Depth of, <a href="#Page_176">176</a>.</li>

-

-<li class="indx">Megatherium, Habits of the, <a href="#Page_135">135</a>.</li>

-

-<li class="indx">Mercury, the Planet, Temperature of, <a href="#Page_82">82</a>.</li>

-

-<li class="indx">Mer de Glace, Flow of the, <a href="#Page_110">110</a>.<span class="pagenum"><a name="Page_246" id="Page_246">246</a></span></li>

-

-<li class="indx">Meteoric Stones, no Fossil, <a href="#Page_92">92</a>.</li>

-

-<li class="indx">Meteorites, Immense, <a href="#Page_91">91</a>.</li>

-

-<li class="indx">Meteorites from the Moon, <a href="#Page_89">89</a>.</li>

-

-<li class="indx">Meteors, Vast Shower of, <a href="#Page_91">91</a>.</li>

-

-<li class="indx">Microscope, the Eye, Brain, and Hair seen by, <a href="#Page_41">41</a>.</li>

-

-<li class="indx">Microscope, Fish-eye, How to make, <a href="#Page_40">40</a>.</li>

-

-<li class="indx">Microscope, Invention of the, <a href="#Page_39">39</a>.</li>

-

-<li class="indx">Microscope for Mineralogists, <a href="#Page_42">42</a>.</li>

-

-<li class="indx">Microscope and the Sea, <a href="#Page_42">42</a>.</li>

-

-<li class="indx">Microscopes, Diamond Lenses for, <a href="#Page_40">40</a>.</li>

-

-<li class="indx">Microscopes, Leuwenhoeck’s, <a href="#Page_40">40</a>.</li>

-

-<li class="indx">Microscopic Writing, <a href="#Page_42">42</a>.</li>

-

-<li class="indx">Milky Way, the, Unfathomable, <a href="#Page_85">85</a>.</li>

-

-<li class="indx">Mineralogy and Geometry, Union of, <a href="#Page_25">25</a>.</li>

-

-<li class="indx">Mirror, Magic, How to make, <a href="#Page_43">43</a>.</li>

-

-<li class="indx">Moon’s Attraction, the, <a href="#Page_73">73</a>.</li>

-

-<li class="indx">Moon, Has it an Atmosphere?, <a href="#Page_69">69</a>.</li>

-

-<li class="indx">Moon, Life in the, <a href="#Page_71">71</a>.</li>

-

-<li class="indx">Moon, Light of the, <a href="#Page_70">70</a>.</li>

-

-<li class="indx">Moon, Mountains in, <a href="#Page_72">72</a>.</li>

-

-<li class="indx">Moon, Measuring the Earth by, <a href="#Page_74">74</a>.</li>

-

-<li class="indx">Moon seen through the Rosse Telescope, <a href="#Page_72">72</a>.</li>

-

-<li class="indx">Moon, Scenery of, <a href="#Page_71">71</a>.</li>

-

-<li class="indx">Moon and Weather, the, <a href="#Page_73">73</a>.</li>

-

-<li class="indx">Moonlight, Heat of, <a href="#Page_70">70</a>.</li>

-

-<li class="indx">“More Worlds than One,” <a href="#Page_56">56</a>, <a href="#Page_57">57</a>.</li>

-

-<li class="indx">Mountain-chains, Elevation of, <a href="#Page_107">107</a>.</li>

-

-<li class="indx">Music of the Spheres, <a href="#Page_55">55</a>.</li>

-

-<li class="indx">Musket-balls found in Ivory, <a href="#Page_237">237</a>.</li>

-

-<li class="ifrst">Natural and Supernatural, the, <a href="#Page_6">6</a>.</li>

-

-<li class="indx">Nautical Almanac, Errors in, <a href="#Page_185">185</a>.</li>

-

-<li class="indx">Nebulæ, Distances of, <a href="#Page_85">85</a>.</li>

-

-<li class="indx">Nebular Hypothesis, the, <a href="#Page_86">86</a>.</li>

-

-<li class="indx">Neptune, the Planet, Discovery of, <a href="#Page_83">83</a>.</li>

-

-<li class="indx">Newton, Sir Isaac, his “Apple-tree,” <a href="#Page_8">8</a>.</li>

-

-<li class="indx">Newton upon Burnet’s Theory of the Earth, <a href="#Page_125">125</a>.</li>

-

-<li class="indx">Newton’s Dog “Diamond,” <a href="#Page_8">8</a>.</li>

-

-<li class="indx">Newton’s first Reflecting Telescope, <a href="#Page_94">94</a>.</li>

-

-<li class="indx">Newton’s “Principia,” <a href="#Page_9">9</a>.</li>

-

-<li class="indx">Newton’s Rooms at Cambridge, <a href="#Page_7">7</a>.</li>

-

-<li class="indx">Newton’s Scale of Colours, <a href="#Page_49">49</a>.</li>

-

-<li class="indx">Newton’s Soap-bubble Experiments, <a href="#Page_49">49</a>, <a href="#Page_50">50</a>.</li>

-

-<li class="indx">New Zealand, Extinct Birds of, <a href="#Page_139">139</a>.</li>

-

-<li class="indx">Niagara, the Roar of, <a href="#Page_28">28</a>.</li>

-

-<li class="indx">Nineveh, Rock-crystal Lens found at, <a href="#Page_39">39</a>.</li>

-

-<li class="indx">Non-conducting Bodies, <a href="#Page_215">215</a>.</li>

-

-<li class="indx">Nothing Lost in the Material World, <a href="#Page_18">18</a>.</li>

-

-<li class="ifrst">Objects really of no Colour, <a href="#Page_37">37</a>.</li>

-

-<li class="indx">Objects, Visibility of, <a href="#Page_30">30</a>.</li>

-

-<li class="indx">Observation, the Art of, <a href="#Page_3">3</a>.</li>

-

-<li class="indx">Observatory, Lacaille’s, <a href="#Page_101">101</a>.</li>

-

-<li class="indx">Observatory, the London Monument, <a href="#Page_103">103</a>.</li>

-

-<li class="indx">Observatory, Shirburn Castle, <a href="#Page_101">101</a>.</li>

-

-<li class="indx">Ocean and Air, Depths of unknown, <a href="#Page_174">174</a>.</li>

-

-<li class="indx">Ocean Highways, <a href="#Page_184">184</a>.</li>

-

-<li class="indx">Ocean, Stability of the, <a href="#Page_12">12</a>.</li>

-

-<li class="indx">Ocean, Transparency of the, <a href="#Page_171">171</a>.</li>

-

-<li class="indx">“Oldest piece of Wood upon the Earth,” <a href="#Page_142">142</a>.</li>

-

-<li class="indx">Optical Effects, Curious, at the Cape, <a href="#Page_38">38</a>.</li>

-

-<li class="indx">Optical Instruments, Late Invention of, <a href="#Page_100">100</a>.</li>

-

-<li class="indx">Oxford and Cambridge, Science at, <a href="#Page_1">1</a>.</li>

-

-<li class="ifrst">Pascal, How he weighed the Atmosphere, <a href="#Page_148">148</a>.</li>

-

-<li class="indx">Pebbles, on, <a href="#Page_106">106</a>.</li>

-

-<li class="indx">Pendulum Experiments, <a href="#Page_16">16&ndash;22</a>.</li>

-

-<li class="indx">Pendulum, the Earth weighed by, <a href="#Page_200">200</a>.</li>

-

-<li class="indx">Pendulums, Influence of on each other, <a href="#Page_200">200</a>.</li>

-

-<li class="indx">Perpetual Fire, <a href="#Page_117">117</a>.</li>

-

-<li class="indx">Petrifaction of Human Bodies, <a href="#Page_131">131</a>.</li>

-

-<li class="indx">Phenomena, Mutual Relations of, <a href="#Page_4">4</a>.</li>

-

-<li class="indx">Philosophers’ False Estimates, <a href="#Page_5">5</a>.</li>

-

-<li class="indx">Phosphorescence of Plants, <a href="#Page_35">35</a>.</li>

-

-<li class="indx">Phosphorescence of the Sea, <a href="#Page_35">35</a>.</li>

-

-<li class="indx">Photo-galvanic Engraving, <a href="#Page_47">47</a>.</li>

-

-<li class="indx">Photograph and Stereoscope, <a href="#Page_47">47</a>.</li>

-

-<li class="indx">Photographic effects of Lightning, <a href="#Page_45">45</a>.</li>

-

-<li class="indx">Photographic Surveying, <a href="#Page_46">46</a>.</li>

-

-<li class="indx">Photographs on the Retina, <a href="#Page_236">236</a>.</li>

-

-<li class="indx">Photography, Best Sky for, <a href="#Page_45">45</a>.</li>

-

-<li class="indx">Photography, Magic of, <a href="#Page_44">44</a>.</li>

-

-<li class="indx">Pisa, Leaning Tower of, <a href="#Page_15">15</a>.</li>

-

-<li class="indx">Planetary System, Origin of our, <a href="#Page_86">86</a>.</li>

-

-<li class="indx">Planets, Diversities of, <a href="#Page_79">79</a>.</li>

-

-<li class="indx">Planetoids, List of the, and their Discoverers, <a href="#Page_239">239</a>.</li>

-

-<li class="indx">Plato’s Survey of the Sciences, <a href="#Page_2">2</a>.<span class="pagenum"><a name="Page_247" id="Page_247">247</a></span></li>

-

-<li class="indx">Pleiades, the, <a href="#Page_77">77</a>.</li>

-

-<li class="indx">Plurality of Worlds, <a href="#Page_57">57</a>.</li>

-

-<li class="indx">Polar Ice, Immensity of, <a href="#Page_181">181</a>.</li>

-

-<li class="indx">Polar Iceberg, <a href="#Page_180">180</a>.</li>

-

-<li class="indx">Polarisation of Light, <a href="#Page_33">33</a>.</li>

-

-<li class="indx">Pole, Open Sea at the, <a href="#Page_181">181</a>.</li>

-

-<li class="indx">Pole-Star of 4000 years ago, <a href="#Page_76">76</a>.</li>

-

-<li class="indx">Profitable Science, <a href="#Page_139">139</a>.</li>

-

-<li class="indx">Pterodactyl, the, <a href="#Page_130">130</a>.</li>

-

-<li class="indx">Pyramid, Duration of the, <a href="#Page_14">14</a>.</li>

-

-<li class="ifrst">Quartz, Down of, <a href="#Page_42">42</a>.</li>

-

-<li class="ifrst">Rain, All in the World, <a href="#Page_155">155</a>.</li>

-

-<li class="indx">Rain, an Inch on the Atlantic, <a href="#Page_156">156</a>.</li>

-

-<li class="indx">Rain-Drops, Size of, <a href="#Page_154">154</a>.</li>

-

-<li class="indx">Rain, How the North Wind drives it away, <a href="#Page_154">154</a>.</li>

-

-<li class="indx">Rain, Philosophy of, <a href="#Page_153">153</a>.</li>

-

-<li class="indx">Rainless Districts, <a href="#Page_155">155</a>.</li>

-

-<li class="indx">Rain-making Vapour, from South to North, <a href="#Page_152">152</a>.</li>

-

-<li class="indx">Rainy Climate, Inordinate, <a href="#Page_154">154</a>.</li>

-

-<li class="indx">Red Sea and Mediterranean Levels, <a href="#Page_175">175</a>.</li>

-

-<li class="indx">Red Sea, Colour of, <a href="#Page_176">176</a>.</li>

-

-<li class="indx">Repulsion of Bodies, <a href="#Page_216">216</a>.</li>

-

-<li class="indx">Rhinoceros of Britain, <a href="#Page_135">135</a>.</li>

-

-<li class="indx">River-water on the Ocean, <a href="#Page_181">181</a>.</li>

-

-<li class="indx">Rose, no Fossil, <a href="#Page_142">142</a>.</li>

-

-<li class="indx">Rosse, the Earl of, his “Telescope,” <a href="#Page_96">96&ndash;99</a>.</li>

-

-<li class="indx">Rotation-Magnetism discovered, <a href="#Page_199">199</a>.</li>

-

-<li class="indx">Rotation, the Axis of, <a href="#Page_11">11</a>.</li>

-

-<li class="ifrst">St. Paul’s Cathedral, how protected from Lightning, <a href="#Page_167">167</a>.</li>

-

-<li class="indx">Salt, All in the Sea, <a href="#Page_179">179</a>.</li>

-

-<li class="indx">Salt Lake of Utah, <a href="#Page_113">113</a>.</li>

-

-<li class="indx">Salt, Solvent Action of, <a href="#Page_115">115</a>.</li>

-

-<li class="indx">Saltness of the Sea, How to tell, <a href="#Page_179">179</a>.</li>

-

-<li class="indx">Sand in the Hour-glass, <a href="#Page_20">20</a>.</li>

-

-<li class="indx">Sand of the Sea and Desert, <a href="#Page_106">106</a>.</li>

-

-<li class="indx">Saturn’s Ring, Was it known to the Ancients?, <a href="#Page_81">81</a>.</li>

-

-<li class="indx">Schwabe, on Sun-Spots, <a href="#Page_68">68</a>.</li>

-

-<li class="indx">Science at Oxford and Cambridge, <a href="#Page_1">1</a>.</li>

-

-<li class="indx">Science of the Ancient World, <a href="#Page_1">1</a>.</li>

-

-<li class="indx">Science, Theoretical, Practical Results of, <a href="#Page_4">4</a>.</li>

-

-<li class="indx">Sciences, Plato’s Survey of, <a href="#Page_2">2</a>.</li>

-

-<li class="indx">Scientific Treatise, the Earliest English, <a href="#Page_5">5</a>.</li>

-

-<li class="indx">Scoresby, Dr., on the Rosse Telescope, <a href="#Page_99">99</a>.</li>

-

-<li class="indx">Scratches, Colours of, <a href="#Page_36">36</a>.</li>

-

-<li class="indx">Sea, Bottles and Currents at, <a href="#Page_172">172</a>.</li>

-

-<li class="indx">Sea, Bottom of, a burial-place, <a href="#Page_177">177</a>.</li>

-

-<li class="indx">Sea, Circulation of the, <a href="#Page_170">170</a>.</li>

-

-<li class="indx">Sea, Climates of the, <a href="#Page_170">170</a>.</li>

-

-<li class="indx">Sea, Deep, Life of the, <a href="#Page_174">174</a>.</li>

-

-<li class="indx">Sea, Greatest ascertained Depth of, <a href="#Page_175">175</a>.</li>

-

-<li class="indx">Sea, Solitude at, <a href="#Page_172">172</a>.</li>

-

-<li class="indx">Sea, Temperature of the, <a href="#Page_170">170</a>.</li>

-

-<li class="indx">Sea, Why is it Salt?, <a href="#Page_177">177</a>.</li>

-

-<li class="indx">Seas, Primeval, Depth of, <a href="#Page_234">234</a>.</li>

-

-<li class="indx">Sea-breezes and Land-breezes illustrated, <a href="#Page_150">150</a>.</li>

-

-<li class="indx">Sea-milk, What is it?, <a href="#Page_176">176</a>.</li>

-

-<li class="indx">Sea-routes, How shortened, <a href="#Page_184">184</a>.</li>

-

-<li class="indx">Sea-shells and Animalcules, Services of, <a href="#Page_234">234</a>.</li>

-

-<li class="indx">Sea-shells, Why found at Great Heights, <a href="#Page_106">106</a>.</li>

-

-<li class="indx">Sea-water, to imitate, <a href="#Page_235">235</a>.</li>

-

-<li class="indx">Sea-water, Properties of, <a href="#Page_179">179</a>.</li>

-

-<li class="indx">Serapis, Temple of, Successive Changes in, <a href="#Page_111">111</a>.</li>

-

-<li class="indx">Sheep, Geology of the, <a href="#Page_138">138</a>.</li>

-

-<li class="indx">Shells, Geometry of, <a href="#Page_232">232</a>.</li>

-

-<li class="indx">Shells, Hydraulic Theory of, <a href="#Page_233">233</a>.</li>

-

-<li class="indx">Siamese Twins, the, galvanised, <a href="#Page_203">203</a>.</li>

-

-<li class="indx">Skin, Dark Colour of the, <a href="#Page_63">63</a>.</li>

-

-<li class="indx">Smith, William, the Geologist, <a href="#Page_126">126</a>.</li>

-

-<li class="indx">Snow, Absence of in Siberia, <a href="#Page_159">159</a>.</li>

-

-<li class="indx">Snow, Impurity of, <a href="#Page_158">158</a>.</li>

-

-<li class="indx">Snow Phenomenon, <a href="#Page_158">158</a>.</li>

-

-<li class="indx">Snow, Warmth of, in Arctic Latitudes, <a href="#Page_158">158</a>.</li>

-

-<li class="indx">Snow-capped Volcano, the, <a href="#Page_119">119</a>.</li>

-

-<li class="indx">Snow-crystals observed by the Chinese, <a href="#Page_159">159</a>.</li>

-

-<li class="indx">Soap-bubble, Science of the, <a href="#Page_48">48</a>.</li>

-

-<li class="indx">Solar Heat, Extreme, <a href="#Page_63">63</a>.</li>

-

-<li class="indx">Solar System, Velocity of, <a href="#Page_59">59</a>.</li>

-

-<li class="indx">Sound, Figures produced by, <a href="#Page_28">28</a>.</li>

-

-<li class="indx">Sound in rarefied Air, <a href="#Page_27">27</a>.</li>

-

-<li class="indx">Sounding Sand, <a href="#Page_27">27</a>.</li>

-

-<li class="indx">Space, Infinite, <a href="#Page_86">86</a>.</li>

-

-<li class="indx">Speed, Varieties of, <a href="#Page_17">17</a>.</li>

-

-<li class="indx">Spheres, Music of the, <a href="#Page_55">55</a>.</li>

-

-<li class="indx">Spots on the Sun, <a href="#Page_67">67</a>.</li>

-

-<li class="indx">Star, Fixed, the nearest, <a href="#Page_78">78</a>.</li>

-

-<li class="indx">Stars’ Colour, Change in, <a href="#Page_77">77</a>.</li>

-

-<li class="indx">Star’s Light sixteen times that of the Sun, <a href="#Page_79">79</a>.</li>

-

-<li class="indx">Stars, Number of, <a href="#Page_75">75</a>.<span class="pagenum"><a name="Page_248" id="Page_248">248</a></span></li>

-

-<li class="indx">Stars seen by Daylight, <a href="#Page_102">102</a>.</li>

-

-<li class="indx">Stars that have disappeared, <a href="#Page_76">76</a>.</li>

-

-<li class="indx">Stars, Why created, <a href="#Page_75">75</a>.</li>

-

-<li class="indx">Stereoscope and Photograph, <a href="#Page_47">47</a>.</li>

-

-<li class="indx">Stereoscope simplified, <a href="#Page_47">47</a>.</li>

-

-<li class="indx">Storm, Impetus of, <a href="#Page_164">164</a>.</li>

-

-<li class="indx">Storms, Revolving, <a href="#Page_164">164</a>.</li>

-

-<li class="indx">Storms, to tell the Approach of, <a href="#Page_163">163</a>.</li>

-

-<li class="indx">Storm-glass, How to make, <a href="#Page_164">164</a>.</li>

-

-<li class="indx">Succession of life in Time, <a href="#Page_128">128</a>.</li>

-

-<li class="indx">Sun, Actinic Power of, <a href="#Page_62">62</a>.</li>

-

-<li class="indx">Sun and Fixed Stars’ Light compared, <a href="#Page_64">64</a>.</li>

-

-<li class="indx">Sun and Terrestrial Magnetism, <a href="#Page_64">64</a>.</li>

-

-<li class="indx">“Sun Darkened,” <a href="#Page_64">64</a>.</li>

-

-<li class="indx">Sun, Great Size of, on Horizon, <a href="#Page_61">61</a>.</li>

-

-<li class="indx">Sun, Heating Power of, <a href="#Page_62">62</a>.</li>

-

-<li class="indx">Sun, Lost Heat of, <a href="#Page_103">103</a>.</li>

-

-<li class="indx">Sun, Luminous Disc of, <a href="#Page_60">60</a>.</li>

-

-<li class="indx">Sun, Nature of the, <a href="#Page_59">59</a>, <a href="#Page_238">238</a>.</li>

-

-<li class="indx">Sun, Spots on, <a href="#Page_67">67</a>.</li>

-

-<li class="indx">Sun, Translatory Motion of, <a href="#Page_61">61</a>.</li>

-

-<li class="indx">Sun’s Distance by the Yard Measure, <a href="#Page_66">66</a>.</li>

-

-<li class="indx">Sun’s Heat, Is it decreasing?, <a href="#Page_65">65</a>.</li>

-

-<li class="indx">Sun’s Rays increasing the Strength of Magnets, <a href="#Page_196">196</a>.</li>

-

-<li class="indx">Sun’s Light and Terrestrial Lights, <a href="#Page_61">61</a>.</li>

-

-<li class="indx">Sun-dial, Universal, <a href="#Page_65">65</a>.</li>

-

-<li class="ifrst">Telegraph, the Atlantic, <a href="#Page_226">226</a>.</li>

-

-<li class="indx">Telegraph, the Electric, <a href="#Page_220">220</a>.</li>

-

-<li class="indx">Telescope and Microscope, the, <a href="#Page_38">38</a>.</li>

-

-<li class="indx">Telescope, Galileo’s, <a href="#Page_93">93</a>.</li>

-

-<li class="indx">Telescope, Herschel’s, <a href="#Page_95">95</a>.</li>

-

-<li class="indx">Telescope, Newton’s first Reflecting, <a href="#Page_94">94</a>.</li>

-

-<li class="indx">Telescopes, Antiquity of, <a href="#Page_94">94</a>.</li>

-

-<li class="indx">Telescopes, Gigantic, proposed, <a href="#Page_99">99</a>.</li>

-

-<li class="indx">Telescopes, the Earl of Rosse’s, <a href="#Page_96">96</a>.</li>

-

-<li class="indx">Temperature and Electricity, <a href="#Page_208">208</a>.</li>

-

-<li class="indx">Terrestrial Magnetism, Origin of, <a href="#Page_200">200</a>.</li>

-

-<li class="indx">Thames, the, and its Salt-water Bed, <a href="#Page_182">182</a>.</li>

-

-<li class="indx">Threads, the two Electric, <a href="#Page_215">215</a>.</li>

-

-<li class="indx">Thunderstorm seen from a Balloon, <a href="#Page_169">169</a>.</li>

-

-<li class="indx">Tides, How produced by Sun and Moon, <a href="#Page_66">66</a>.</li>

-

-<li class="indx">Time an Element of Force, <a href="#Page_19">19</a>.</li>

-

-<li class="indx">Time, Minute Measurement of, <a href="#Page_194">194</a>.</li>

-

-<li class="indx">Topaz, Transmutation of, <a href="#Page_37">37</a>.</li>

-

-<li class="indx">Trilobite, the, <a href="#Page_138">138</a>.</li>

-

-<li class="indx">Tuning-fork a Flute-player, <a href="#Page_28">28</a>.</li>

-

-<li class="indx">Twilight, Beauty of, <a href="#Page_148">148</a>.</li>

-

-<li class="ifrst">Universe, Vast Numbers in, <a href="#Page_75">75</a>.</li>

-

-<li class="indx">Utah, Salt Lake of, <a href="#Page_113">113</a>.</li>

-

-<li class="ifrst">Velocity of the Solar System, <a href="#Page_59">59</a>.</li>

-

-<li class="indx">Vesta and Pallas, Speculations on, <a href="#Page_82">82</a>.</li>

-

-<li class="indx">Vesuvius, Great Eruptions of, <a href="#Page_119">119</a>.</li>

-

-<li class="indx">Vibration of Heated Metals, <a href="#Page_188">188</a>.</li>

-

-<li class="indx">Visibility of Objects, <a href="#Page_30">30</a>.</li>

-

-<li class="indx">Voice, Human, Audibility of, <a href="#Page_27">27</a>.</li>

-

-<li class="indx">Volcanic Action and Geological Change, <a href="#Page_118">118</a>.</li>

-

-<li class="indx">Volcanic Dust, Travels of, <a href="#Page_119">119</a>.</li>

-

-<li class="indx">Volcanic Islands, Disappearance of, <a href="#Page_117">117</a>.</li>

-

-<li class="indx">Voltaic Battery and the Gymnotus, <a href="#Page_206">206</a>.</li>

-

-<li class="indx">Voltaic Currents in Mines, <a href="#Page_206">206</a>.</li>

-

-<li class="indx">Voltaic Electricity discovered, <a href="#Page_205">205</a>.</li>

-

-<li class="ifrst">Watches, Harrison’s Prize, <a href="#Page_229">229</a>.</li>

-

-<li class="indx">Water decomposed by Electricity, <a href="#Page_208">208</a>.</li>

-

-<li class="indx">Water, Running, Force of, <a href="#Page_114">114</a>.</li>

-

-<li class="indx">Waters of the Globe gradually decreasing, <a href="#Page_113">113</a>.</li>

-

-<li class="indx">Water-Purifiers, Natural, <a href="#Page_234">234</a>.</li>

-

-<li class="indx">Waterspouts, How formed in the Java Sea, <a href="#Page_160">160</a>.</li>

-

-<li class="indx">Waves, Cause of, <a href="#Page_183">183</a>.</li>

-

-<li class="indx">Waves, Force of, <a href="#Page_184">184</a>.</li>

-

-<li class="indx">Waves, Rate of Travelling, <a href="#Page_183">183</a>.</li>

-

-<li class="indx">Wenham-Lake Ice, Purity of, <a href="#Page_161">161</a>.</li>

-

-<li class="indx">West, Superior Salubrity of, <a href="#Page_150">150</a>.</li>

-

-<li class="indx">“White Water,” and Luminous Animals at Sea, <a href="#Page_173">173</a>.</li>

-

-<li class="indx">Winds, Transporting Power of, <a href="#Page_163">163</a>.</li>

-

-<li class="indx">Wollaston’s Minute Battery, <a href="#Page_204">204</a>.</li>

-

-<li class="indx">World, All the, in Motion, <a href="#Page_11">11</a>.</li>

-

-<li class="indx">World, the, in a Nutshell, <a href="#Page_13">13</a>.</li>

-

-<li class="indx">Worlds, More than One, <a href="#Page_56">56</a>.</li>

-

-<li class="indx">Worlds to come, <a href="#Page_58">58</a>.</li>

-</ul>

-</div>

-

-<p class="p2 center small">LONDON: ROBSON, LEVEY, AND FRANKLYN, GREAT NEW STREET AND PETTER LANE, E.C.</p>

-

-<div class="chapter"></div>

-<div class="transnote">

-<h2 class="nobreak"><a name="Transcribers_Notes" id="Transcribers_Notes"></a>Transcriber’s Notes</h2>

-

-<p>Punctuation, hyphenation, and spelling were made consistent when a predominant

-preference was found in this book; otherwise they were not changed.</p>

-

-<p>Simple typographical errors were corrected; occasional unbalanced

-quotation marks retained.</p>

-

-<p>Ambiguous hyphens at the ends of lines were retained.</p>

-

-<p>Some numbers in equations include a hyphen to separate

-the fractional and integer parts. These are not minus signs,

-which, like other arithmetic operators, are surrounded by spaces.</p>

-

-<p>The original book apparently used a smaller font for multiple

-reasons, but as those reasons were not always clear to the

-Transcriber, smaller text is indented by 2 spaces in the Plain Text

-version of this eBook, and is displayed smaller in other versions.</p>

-

-<p>Footnotes, originally at the bottoms of pages, have been

-collected and repositioned just before the Index.</p>

-

-<p>Devices that cannot display some of the characters used for column

-alignment in the tables of this eBook may substitute question marks

-or hollow squares.</p>

-

-<p>Page <a href="#Page_59">59</a>: “95 × 1·623 = 154·185” was misprinted as

-“95 + 1·623 = 154·185” and has been corrected here.</p>

-

-<p>The Table of Contents does not list the “<a href="#Phenomena">Phenomena of Heat</a>”

-chapter, which begins on page <a href="#Page_185">185</a>; nor the <a href="#GENERAL_INDEX">Index</a>, which

-begins on page <a href="#Page_242">242</a>.</p>

-

-<p>Page <a href="#Page_95">95</a>: “adjustible” was printed that way.</p>

-

-<p>Page <a href="#Page_151">151</a>: Missing closing quotation mark added after

-“rapidly evaporate in space.” It may belong elsewhere.</p>

-

-<p>Page <a href="#Page_221">221</a>: Missing closing quotation mark not added for

-phrase beginning “it is a fine invention”.</p>

-</div>

-

-

-

-

-

-

-

-

-<pre>

-

-

-

-

-

-End of the Project Gutenberg EBook of Curiosities of Science, Past and

-Present, by John Timbs

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+<body>
+<div>*** START OF THE PROJECT GUTENBERG EBOOK 48516 ***</div>
+
+<div class="poem-container">
+<div class="iblock" style="max-width: 30em; border: thin solid black; padding: 1em;">
+<p class="center larger" style="font-family: sans-serif, serif;">
+NEW WORK ON PAINTING.</p>
+
+<p class="p1 center"><i>Just ready, in small 8vo, with Frontispiece and Vignette</i>,</p>
+
+<p class="p1 center large vspace wspace">PAINTING
+POPULARLY EXPLAINED;</p>
+
+<p class="p1 center vspace"><span class="smaller">WITH</span><br />
+<span class="larger">The Practice of the Art,</span><br />
+<span class="smaller">AND</span><br />
+<span class="larger">HISTORICAL NOTICES OF ITS PROGRESS.</span></p>
+
+<p class="center"><span class="smaller">BY</span><br />
+<span class="larger">THOMAS J. GULLICK, <span class="smcap">Painter</span>,</span><br />
+<span class="smaller">AND</span><br />
+<span class="larger">JOHN TIMBS, F.S.A.</span>
+</p>
+
+<p class="p2">The plan of this work is thus sketched in the <i>Introduction</i>:</p>
+
+<blockquote>
+
+<p>“There have been in the history of Art, four grand styles of
+imitating Nature&mdash;Tempera, Encaustic, Fresco, and Oil. These,
+together with the minor modes of Painting, we propose arranging
+in something like chronological sequence; but our design being to
+offer an explanation of the Art derived from practical acquaintance,
+rather than attempt to give its history, we shall confine ourselves
+for the most part to so much only of the History of Painting as is
+necessary to elucidate the origin of the different practices which have
+obtained at different periods.”</p>
+
+<p>By this means, the Authors hope to produce a work which may
+be valuable to the Amateur, and interesting to the Connoisseur, the
+Artist, and the General Reader.</p></blockquote>
+
+<p class="p1 larger center"><span class="gesperrt">LONDON:</span><br />
+KENT &amp; CO. (<span class="smcap smaller">late Bogue</span>), FLEET STREET.</p>
+</div></div>
+
+<div class="newpage p4">
+<div class="figcenter" style="width: 450px;">
+<img src="images/i_frontis.jpg" width="392" height="600" alt="" />
+<div class="caption"><p>MOUTH OF THE GREAT ROSSE TELESCOPE, AT PARSONSTOWN.</p>
+
+<p>FROM A PHOTOGRAPH.</p></div>
+</div></div>
+
+<hr />
+
+<p class="newpage p4 center large vspace wspace">
+Things not generally Known<br />
+Familiarly Explained.</p>
+
+<h1 class="vspace wspace">CURIOSITIES OF SCIENCE,<br />
+<span class="small">Past and Present.<br />
+A BOOK FOR OLD AND YOUNG.</span></h1>
+
+<p class="p2 center"><span class="smcap">By</span> JOHN TIMBS, F.S.A.</p>
+
+<p class="p1 center small">AUTHOR OF THINGS NOT GENERALLY KNOWN; AND EDITOR OF THE<br />
+YEAR-BOOK OF FACTS.</p>
+
+<div class="p2 figcenter" style="width: 450px;">
+<img src="images/i_vignette.jpg" width="300" height="286" alt="" />
+<div class="caption"><p>Model of the Safety-Lamp, made by Sir Humphry Davy’s own hands;<br />
+in the possession of the Royal Society.</p></div>
+</div>
+
+<p class="p2 center">
+LONDON:<br />
+KENT AND CO. (<span class="smcap">late BOGUE</span>), FLEET STREET.<br />
+MDCCCLVIII.
+</p>
+
+<hr />
+
+<p class="newpage p4 center">
+<i>The Author reserves the right of authorising a Translation of this Work.</i></p>
+
+<p class="p2 center small vspace">LONDON:<br />
+PRINTED BY LEVEY, ROBSON, AND FRANKLYN,<br />
+Great New Street and Fetter Lane.
+</p>
+
+<hr />
+
+<div class="chapter"></div>
+<p class="newpage p4 in0 in4">
+<span class="smcap">Gentle Reader</span>,
+</p>
+
+<p>The volume of “<span class="smcap">Curiosities</span>” which I here present to your
+notice is a portion of the result of a long course of reading, observation,
+and research, necessary for the compilation of thirty volumes
+of “Arcana of Science” and “Year-Book of Facts,” published
+from 1828 to 1858. Throughout this period&mdash;nearly half of the
+Psalmist’s “days of our years”&mdash;I have been blessed with health
+and strength to produce these volumes, year by year (with one
+exception), upon the appointed day; and this with unbroken attention
+to periodical duties, frequently rendered harassing or
+ungenial. Nevertheless, during these three decades I have found
+my account in the increasing approbation of the reading public,
+which has been so largely extended to the series of “<span class="smcap">Things not
+generally Known</span>,” of which the present volume of “<span class="smcap">Curiosities
+of Science</span>” is an instalment. I need scarcely add, that in its progressive
+preparation I have endeavoured to compare, weigh, and
+consider, the contents, so as to combine the experience of the Past
+with the advantages of the Present.</p>
+
+<p>In these days of universal attainments, when Science becomes
+not merely a luxury to the rich, but bread to the poor, and when
+the very amusements as well as the conveniences of life have taken
+a scientific colour, it is reasonable to hope that the present volume
+may be acceptable to a large class of seekers after “things not
+generally known.” For this purpose, I have aimed at soundness as
+well as popularity; although, for myself, I can claim little beyond
+being one of those industrious “ants of science” who garner facts,
+and by selection and comparison adapt them for a wider circle of
+readers than they were originally expected to reach. In each case,
+as far as possible, these “<span class="smcap">Curiosities</span>” bear the mint-mark of authority;
+and in the living list are prominent the names of Humboldt
+and Herschel, Airy and Whewell, Faraday, Brewster, Owen, and
+Agassiz, Maury, Wheatstone, and Hunt, from whose writings and
+researches the following pages are frequently enriched.</p>
+
+<p>The sciences here illustrated are, in the main, Astronomy and
+Meteorology; Geology and Paleontology; Physical Geography;
+Sound, Light, and Heat; Magnetism and Electricity,&mdash;the latter
+with special attention to the great marvel of our times, the Electro-magnetic
+Telegraph. I hope, at no very distant period, to extend
+the “<span class="smcap">Curiosities</span>” to another volume, to include branches of
+Natural and Experimental Science which are not here presented.</p>
+
+<p class="sigright">
+I. T.</p>
+
+<p><i>November 1858.</i></p>
+
+<hr />
+
+<div class="chapter"></div>
+<h2><a name="CONTENTS" id="CONTENTS"></a>CONTENTS.</h2>
+
+<table class="vspace" summary="Contents">
+  <tr class="small">
+    <td> </td>
+    <td class="tdr">PAGE</td></tr>
+  <tr>
+    <td class="tdl"><span class="smcap">Introductory</span></td>
+    <td class="tdr"><a href="#Introductory">1&ndash;10</a></td></tr>
+  <tr>
+    <td class="tdl"><span class="smcap">Physical Phenomena</span></td>
+    <td class="tdr"><a href="#Physical">11&ndash;26</a></td></tr>
+  <tr>
+    <td class="tdl"><span class="smcap">Sound and Light</span></td>
+    <td class="tdr"><a href="#Sound">27&ndash;53</a></td></tr>
+  <tr>
+    <td class="tdl"><span class="smcap">Astronomy</span></td>
+    <td class="tdr"><a href="#Astronomy">54&ndash;103</a></td></tr>
+  <tr>
+    <td class="tdl"><span class="smcap">Geology and Paleontology</span></td>
+    <td class="tdr"><a href="#Geology">104&ndash;145</a></td></tr>
+  <tr>
+    <td class="tdl"><span class="smcap">Meteorological Phenomena</span></td>
+    <td class="tdr"><a href="#Meteorological">146&ndash;169</a></td></tr>
+  <tr>
+    <td class="tdl"><span class="smcap">Physical Geography of the Sea</span></td>
+    <td class="tdr"><a href="#Geography">170&ndash;192</a></td></tr>
+  <tr>
+    <td class="tdl"><span class="smcap">Magnetism and Electricity</span></td>
+    <td class="tdr"><a href="#Magnetism">193&ndash;219</a></td></tr>
+  <tr>
+    <td class="tdl"><span class="smcap">The Electric Telegraph</span></td>
+    <td class="tdr"><a href="#Electric">220&ndash;228</a></td></tr>
+  <tr>
+    <td class="tdl"><span class="smcap">Miscellanea</span></td>
+    <td class="tdr"><a href="#Miscellanea">229&ndash;241</a></td></tr>
+</table>
+
+<hr />
+
+<p><span class="pagenum"><a name="Page_vii" id="Page_vii">vii</a></span></p>
+
+<div class="chapter"></div>
+<h2><a name="The_Frontispiece" id="The_Frontispiece"></a>The Frontispiece.</h2>
+
+<h3>THE GREAT ROSSE TELESCOPE.</h3>
+
+<p>The originator and architect of this magnificent instrument had long
+been distinguished in scientific research as Lord Oxmantown; and may
+be considered to have gracefully commemorated his succession to the
+Earldom of Rosse, and his Presidency of the Royal Society, by the completion
+of this marvellous work, with which his name will be hereafter
+indissolubly associated.</p>
+
+<p>The Great Reflecting Telescope at Birr Castle (of which the Frontispiece
+represents a portion<a name="FNanchor_1" id="FNanchor_1" href="#Footnote_1" class="fnanchor">1</a>) will be found fully described at pp. 96&ndash;99
+of the present volume of <i>Curiosities of Science</i>.</p>
+
+<p>This matchless instrument has already disclosed “forms of stellar
+arrangement indicating modes of dynamic action never before contemplated
+in celestial mechanics.” “In these departments of research,&mdash;the
+examination of the configurations of nebulæ, and the resolution of
+nebulæ into stars (says the Rev. Dr. Scoresby),&mdash;the six-feet speculum
+has had its grandest triumphs, and the noble artificer and observer the
+highest rewards of his talents and enterprise. Altogether, the quantity
+of work done during a period of about seven years&mdash;including a
+winter when a noble philanthropy for a starving population absorbed the
+keenest interests of science&mdash;has been decidedly great; and the new
+knowledge acquired concerning the handiwork of the great Creator
+amply satisfying of even sanguine expectation.”</p>
+
+<hr />
+<div class="chapter"></div>
+<h2><a name="The_Vignette" id="The_Vignette"></a>The Vignette.</h2>
+
+<h3>SIR HUMPHRY DAVY’S OWN MODEL OF HIS SAFETY-LAMP.</h3>
+
+<p>Of the several contrivances which have been proposed for safely lighting
+coal-mines subject to the visitation of fire-damp, or carburetted
+hydrogen, the Safety-Lamp of Sir Humphry Davy is the only one which
+has ever been judged safe, and been extensively employed. The inventor
+first turned his attention to the subject in 1815, when Davy
+began a minute chemical examination of fire-damp, and found that it
+required an admixture of a large quantity of atmospheric air to render
+it explosive. He then ascertained that explosions of inflammable gases
+were incapable of being passed through long narrow metallic tubes,
+and that this principle of security was still obtained by diminishing
+their length and increasing their number. This fact led to trials upon
+sieves made of wire-gauze; when Davy found that if a piece of wire-gauze
+was held over the flame of a lamp, or of coal-gas, it prevented
+the flame from passing; and he ascertained that a flame confined in a
+cylinder of very fine wire-gauze did not explode even in a mixture of
+oxygen and hydrogen, but that the gases burnt in it with great vivacity.</p>
+
+<p>These experiments served as the basis of the Safety-Lamp. The
+apertures in the gauze, Davy tells us in his work on the subject, should
+not be more than 1/22d of an inch square. The lamp is screwed on to
+the bottom of the wire-gauze cylinder. When it is lighted, and gradually
+introduced into an atmosphere mixed with fire-damp, the size and
+length of the flame are first increased. When the inflammable gas forms
+as much as 1/12th of the volume of air, the cylinder becomes filled with a
+feeble blue flame, within which the flame of the wick burns brightly, and
+the light of the wick continues till the fire-damp increases to 1/6th or 1/5th;<span class="pagenum"><a name="Page_viii" id="Page_viii">viii</a></span>
+it is then lost in the flame of the fire-damp, which now fills the cylinder
+with a pretty strong light; and when the foul air constitutes one-third
+of the atmosphere it is no longer fit for respiration,&mdash;and this ought to
+be a signal to the miner to leave that part of the workings.</p>
+
+<p>Sir Humphry Davy presented his first communication respecting
+his discovery of the Safety-Lamp to the Royal Society in 1815. This
+was followed by a series of papers remarkable for their simplicity and
+clearness, crowned by that read on the 11th of January 1816, when the
+principle of the Safety-Lamp was announced, and Sir Humphry presented
+to the Society a model made by his own hands, which is to this
+day preserved in the collection of the Royal Society at Burlington House.
+From this interesting memorial the Vignette has been sketched.</p>
+
+<p>There have been several modifications of the Safety-Lamp, and the
+merit of the discovery has been claimed by others, among whom was
+Mr. George Stephenson; but the question was set at rest forty-one
+years since by an examination,&mdash;attested by Sir Joseph Banks, P.R.S.,
+Mr. Brande, Mr. Hatchett, and Dr. Wollaston,&mdash;and awarding the independent
+merit to Davy.</p>
+
+<p>A more substantial, though not a more honourable, testimony of
+approval was given by the coal-owners, who subscribed 2500<i>l.</i> to purchase
+a superb service of plate, which was suitably inscribed and presented
+to Davy.<a name="FNanchor_2" id="FNanchor_2" href="#Footnote_2" class="fnanchor">2</a></p>
+
+<p>Meanwhile the Report by the Parliamentary Committee “cannot
+admit that the experiments (made with the Lamp) have any tendency
+to detract from the character of Sir Humphry Davy, or to disparage
+the fair value placed by himself upon his invention. The improvements
+are probably those which longer life and additional facts would have
+induced him to contemplate as desirable, and of which, had he not been
+the inventor, he might have become the patron.”</p>
+
+<p>The principle of the invention may be thus summed up. In the
+Safety-Lamp, the mixture of the fire-damp and atmospheric air within
+the cage of wire-gauze explodes upon coming in contact with the flame;
+but the combustion cannot pass through the wire-gauze, and being there
+imprisoned, cannot impart to the explosive atmosphere of the mine any
+of its force. This effect has been erroneously attributed to a cooling
+influence of the metal.</p>
+
+<p>Professor Playfair has eloquently described the Safety-Lamp of Davy
+as a present from philosophy to the arts; a discovery in no degree the
+effect of accident or chance, but the result of patient and enlightened
+research, and strongly exemplifying the great use of an immediate and
+constant appeal to experiment. After characterising the invention as
+the <i>shutting-up in a net of the most slender texture</i> a most violent and
+irresistible force, and a power that in its tremendous effects seems to
+emulate the lightning and the earthquake, Professor Playfair thus concludes:
+“When to this we add the beneficial consequences, and the
+saving of the lives of men, and consider that the effects are to remain
+as long as coal continues to be dug from the bowels of the earth, it may
+be fairly said that there is hardly in the whole compass of art or science
+a single invention of which one would rather wish to be the author....
+This,” says Professor Playfair, “is exactly such a case as we should
+choose to place before Bacon, were he to revisit the earth; in order to
+give him, in a small compass, an idea of the advancement which philosophy
+has made since the time when he had pointed out to her the
+route which she ought to pursue.”</p>
+
+<hr />
+
+<p><span class="pagenum"><a name="Page_1" id="Page_1">1</a></span></p>
+
+<div class="chapter"></div>
+<h2><span class="larger">CURIOSITIES OF SCIENCE.</span></h2>
+
+<h2 class="nobreak"><a name="Introductory" id="Introductory"></a>Introductory.</h2>
+
+<h3>SCIENCE OF THE ANCIENT WORLD.</h3>
+
+<p>In every province of human knowledge where we now possess
+a careful and coherent interpretation of nature, men began by
+attempting in bold flights to leap from obvious facts to the
+highest point of generality&mdash;to some wide and simple principle
+which after-ages had to reject. Thus, from the facts that all
+bodies are hot or cold, moist or dry, they leapt at once to the
+doctrine that the world is constituted of four elements&mdash;earth,
+air, fire, water; from the fact that the heavenly bodies circle
+the sky in courses which occur again and again, they at once
+asserted that they move in exact circles, with an exactly uniform
+motion; from the fact that heavy bodies fall through the
+air somewhat faster than light ones, it was assumed that all
+bodies fall quickly or slowly exactly in proportion to their
+weight; from the fact that the magnet attracts iron, and that
+this force of attraction is capable of increase, it was inferred
+that a perfect magnet would have an irresistible force of attraction,
+and that the magnetic pole of the earth would draw
+the nails out of a ship’s bottom which came near it; from the
+fact that some of the finest quartz crystals are found among
+the snows of the Alps, it was inferred that the crystallisation
+of gems is the result of intense and long-continued cold: and
+so on in innumerable instances. Such anticipations as these
+constituted the basis of almost all the science of the ancient
+world; for such principles being so assumed, consequences were
+drawn from them with great ingenuity, and systems of such
+deductions stood in the place of science.&mdash;<i>Edinburgh Review</i>,
+No. 216.</p>
+
+<h3>SCIENCE AT OXFORD AND CAMBRIDGE.</h3>
+
+<p>The earliest science of a decidedly English school is due,
+for the most part, to the University of Oxford, and specially
+to Merton College,&mdash;a foundation of which Wood remarks, that<span class="pagenum"><a name="Page_2" id="Page_2">2</a></span>
+there was no other for two centuries, either in Oxford or Paris,
+which could at all come near it in the cultivation of the sciences.
+But he goes on to say that large chests full of the
+writers of this college were allowed to remain untouched by
+their successors for fear of the magic which was supposed to be
+contained in them. Nevertheless, it is not difficult to trace
+the liberalising effect of scientific study upon the University in
+general, and Merton College in particular; and it must be
+remembered that to the cultivation of the mind at Oxford we
+owe almost all the literary celebrity of the middle ages. In
+this period the University of Cambridge appears to have acquired
+no scientific distinction. Taking as a test the acquisition
+of celebrity on the continent, we find that Bacon, Sacrobosco,
+Greathead, Estwood, &amp;c. were all of Oxford. The
+latter University had its morning of splendour while Cambridge
+was comparatively unknown; it had also its noonday, illustrated
+by such men as Briggs, Wren, Wallis, Halley, and
+Bradley.</p>
+
+<p>The age of science at Cambridge may be said to have begun
+with Francis Bacon; and but that we think much of the difference
+between him and his celebrated namesake lies more in
+time and circumstances than in talents or feelings, we would
+rather date from 1600 with the former than from 1250 with
+the latter. Praise or blame on either side is out of the question,
+seeing that the earlier foundation of Oxford, and its
+superiority in pecuniary means, rendered all that took place
+highly probable; and we are in a great measure indebted for
+the liberty of writing our thoughts, to the cultivation of the
+liberalising sciences at Oxford in the dark ages.</p>
+
+<p>With regard to the University of Cambridge, for a long
+time there hardly existed the materials of any proper instruction,
+even to the extent of pointing out what books should be
+read by a student desirous of cultivating astronomy.</p>
+
+<h3>PLATO’S SURVEY OF THE SCIENCES.</h3>
+
+<blockquote>
+
+<p>Plato, like Francis Bacon, took a review of the sciences of his time:
+he enumerates arithmetic and plane geometry, treated as collections
+of abstract and permanent truths; solid geometry, which he “notes
+as deficient” in his time, although in fact he and his school were in
+possession of the doctrine of the “five regular solids;” astronomy, in
+which he demands a science which should be elevated above the mere
+knowledge of phenomena. The visible appearances of the heavens
+only suggest the problems with which true astronomy deals; as beautiful
+geometrical diagrams do not prove, but only suggest geometrical
+propositions. Finally, Plato notices the subject of harmonics, in which
+he requires a science which shall deal with truths more exact than the
+ear can establish, as in astronomy he requires truths more exact than
+the eye can assure us of.</p>
+
+<p>In a subsequent paper Plato speaks of <i>Dialectic</i> as a still higher<span class="pagenum"><a name="Page_3" id="Page_3">3</a></span>
+element of a philosophical education, fitted to lead men to the knowledge
+of real existences and of the supreme good. Here he describes
+dialectic by its objects and purpose. In other places dialectic is spoken
+of as a method or process of analysis; as in the <i>Phædrus</i>, where Socrates
+describes a good dialectician as one who can divide a subject according
+to its natural members, and not miss the joint, like a bad carver.
+Xenophon says that Socrates derived <i>dialectic</i> from a term implying
+to <i>divide a subject into parts</i>, which Mr. Grote thinks unsatisfactory as
+an etymology, but which has indicated a practical connection in the
+Socratic school. The result seems to be that Plato did not establish
+any method of analysis of a subject as his dialectic; but he conceived
+that the analytical habits formed by the comprehensive study of the
+exact sciences, and sharpened by the practice of dialogue, would lead
+his students to the knowledge of first principles.&mdash;<i>Dr. Whewell.</i></p></blockquote>
+
+<h3>FOLLY OF ATHEISM.</h3>
+
+<p>Morphology, in natural science, teaches us that the whole
+animal and vegetable creation is formed upon certain fundamental
+types and patterns, which can be traced under various
+modifications and transformations through all the rich variety
+of things apparently of most dissimilar build. But here and
+there a scientific person takes it into his foolish head that there
+may be a set of moulds without a moulder, a calculated gradation
+of forms without a calculator, an ordered world without
+an ordering God. Now, this atheistical science conveys about
+as much meaning as suicidal life: for science is possible only
+where there are ideas, and ideas are only possible where there
+is mind, and minds are the offspring of God; and atheism
+itself is not merely ignorance and stupidity,&mdash;it is the purely
+nonsensical and the unintelligible.&mdash;<i>Professor Blackie</i>; <i>Edinburgh
+Essays</i>, 1856.</p>
+
+<h3>THE ART OF OBSERVATION.</h3>
+
+<p>To observe properly in the very simplest of the physical
+sciences requires a long and severe training. No one knows
+this so feelingly as the great discoverer. Faraday once said,
+that he always doubts his own observations. Mitscherlich on
+one occasion remarked to a man of science that it takes
+fourteen years to discover and establish a single new fact in
+chemistry. An enthusiastic student one day betook himself to
+Baron Cuvier with the exhibition of a new organ&mdash;a muscle
+which he supposed himself to have discovered in the body of
+some living creature or other; but the experienced and sagacious
+naturalist kindly bade the young man return to him with
+the same discovery in six months. The Baron would not even
+listen to the student’s demonstration, nor examine his dissection,
+till the eager and youthful discoverer had hung over the
+object of inquiry for half a year; and yet that object was a
+mere thing of the senses.&mdash;<i>North-British Review</i>, No. 18.</p>
+
+<p><span class="pagenum"><a name="Page_4" id="Page_4">4</a></span></p>
+
+<h3>MUTUAL RELATIONS OF PHENOMENA.</h3>
+
+<p>In the observation of a phenomenon which at first sight
+appears to be wholly isolated, how often may be concealed the
+germ of a great discovery! Thus, when Galvani first stimulated
+the nervous fibre of the frog by the accidental contact of
+two heterogeneous metals, his contemporaries could never have
+anticipated that the action of the voltaic pile would discover
+to us in the alkalies metals of a silver lustre, so light as to
+swim on water, and eminently inflammable; or that it would
+become a powerful instrument of chemical analysis, and at the
+same time a thermoscope and a magnet. When Huyghens first
+observed, in 1678, the phenomenon of the polarisation of light,
+exhibited in the difference between two rays into which a pencil
+of light divides itself in passing through a doubly refracting
+crystal, it could not have been foreseen that a century and a
+half later the great philosopher Arago would, by his discovery of
+<i>chromatic polarisation</i>, be led to discern, by means of a small fragment
+of Iceland spar, whether solar light emanates from a solid
+body or a gaseous covering; or whether comets transmit light
+directly, or merely by reflection.&mdash;<i>Humboldt’s Cosmos</i>, vol. i.</p>
+
+<h3>PRACTICAL RESULTS OF THEORETICAL SCIENCE.</h3>
+
+<p>What are the great wonders, the great sources of man’s
+material strength, wealth, and comfort in modern times? The
+Railway, with its mile-long trains of men and merchandise,
+moving with the velocity of the wind, and darting over chasms
+a thousand feet wide; the Electric Telegraph, along which
+man’s thoughts travel with the velocity of light, and girdle the
+earth more quickly than Puck’s promise to his master; the
+contrivance by which the Magnet, in the very middle of a strip
+of iron, is still true to the distant pole, and remains a faithful
+guide to the mariner; the Electrotype process, by which a
+metallic model of any given object, unerringly exact, grows
+into being like a flower. Now, all these wonders are the result
+of recent and profound discoveries in theoretical science. The
+Locomotive Steam-engine, and the Steam-engine in all its other
+wonderful and invaluable applications, derives its efficacy from
+the discoveries, by Watt and others, of the laws of steam. The
+Railway Bridge is not made strong by mere accumulation of
+materials, but by the most exact and careful scientific examination
+of the means of giving the requisite strength to every
+part, as in the great example of Mr. Stephenson’s Britannia
+Bridge over the Menai Strait. The Correction of the Magnetic
+Needle in iron ships it would have been impossible for Mr.
+Airy to secure without a complete theoretical knowledge of<span class="pagenum"><a name="Page_5" id="Page_5">5</a></span>
+the laws of Magnetism. The Electric Telegraph and the Electrotype
+process include in their principles and mechanism the
+most complete and subtle results of electrical and magnetical
+theory.&mdash;<i>Edinburgh Review</i>, No. 216.</p>
+
+<h3>PERPETUITY OF IMPROVEMENT.</h3>
+
+<p>In the progress of society all great and real improvements
+are perpetuated: the same corn which, four thousand years
+ago, was raised from an improved grass by an inventor worshiped
+for two thousand years in the ancient world under the
+name of Ceres, still forms the principal food of mankind; and
+the potato, perhaps the greatest benefit that the old has derived
+from the new world, is spreading over Europe, and will continue
+to nourish an extensive population when the name of the
+race by whom it was first cultivated in South America is forgotten.&mdash;<i>Sir
+H. Davy.</i></p>
+
+<h3>THE EARLIEST ENGLISH SCIENTIFIC TREATISE.</h3>
+
+<p>Geoffrey Chaucer, the poet, wrote a treatise on the Astrolabe
+for his son, which is the earliest English treatise we have
+met with on any scientific subject. It was not completed; and
+the apologies which Chaucer makes to his own child for writing
+in English are curious; while his inference that his son should
+therefore “pray God save the king that is lord of this language,”
+is at least as loyal as logical.</p>
+
+<h3>PHILOSOPHERS’ FALSE ESTIMATES OF THEIR OWN LABOURS.</h3>
+
+<p>Galileo was confident that the most important part of his
+contributions to the knowledge of the solar system was his
+Theory of the Tides&mdash;a theory which all succeeding astronomers
+have rejected as utterly baseless and untenable. Descartes
+probably placed far above his beautiful explanation of
+the rainbow, his <i>à priori</i> theory of the existence of the vortices
+which caused the motion of the planets and satellites. Newton
+perhaps considered as one of the best parts of his optical
+researches his explanation of the natural colour of bodies,
+which succeeding optical philosophers have had to reject; and
+he certainly held very strongly the necessity of a material cause
+for gravity, which his disciples have disregarded. Davy looked
+for his greatest triumph in the application of his discoveries to
+prevent the copper bottoms of ships from being corroded. And
+so in other matters.&mdash;<i>Edinburgh Review</i>, No. 216.</p>
+
+<h3>RELICS OF GENIUS.</h3>
+
+<p>Professor George Wilson, in a lecture to the Scottish Society
+of Arts, says: “The spectacle of these things ministers<span class="pagenum"><a name="Page_6" id="Page_6">6</a></span>
+only to the good impulses of humanity. Isaac Newton’s telescope
+at the Royal Society of London; Otto Guericke’s air-pump
+in the Library at Berlin; James Watt’s repaired Newcomen
+steam-engine in the Natural-Philosophy class-room of
+the College at Glasgow; Fahrenheit’s thermometer in the corresponding
+class-room of the University of Edinburgh; Sir H.
+Davy’s great voltaic battery at the Royal Institution, London,
+and his safety-lamp at the Royal Society; Joseph Black’s
+pneumatic trough in Dr. Gregory’s possession; the first wire
+which Faraday made rotate electro-magnetically, at St. Bartholomew’s
+Hospital; Dalton’s atomic models at Manchester;
+and Kemp’s liquefied gases in the Industrial Museum of Scotland,&mdash;are
+alike personal relics, historical monuments, and
+objects of instruction, which grow more and more precious
+every year, and of which we never can have too many.”</p>
+
+<h3>THE ROYAL SOCIETY: THE NATURAL AND SUPERNATURAL.</h3>
+
+<p>The Royal Society was formed with the avowed object of
+increasing knowledge by direct experiment; and it is worthy
+of remark, that the charter granted by Charles II. to this celebrated
+institution declares that its object is the extension of
+natural knowledge, as opposed to that which is supernatural.</p>
+
+<p>Dr. Paris (<i>Life of Sir H. Davy</i>, vol. ii. p. 178) says: “The
+charter of the Royal Society states that it was established for
+the improvement of <i>natural</i> science. This epithet <i>natural</i> was
+originally intended to imply a meaning, of which very few
+persons, I believe, are aware. At the period of the establishment
+of the society, the arts of witchcraft and divination were
+very extensively encouraged; and the word <i>natural</i> was therefore
+introduced in contradistinction to <i>supernatural</i>.”</p>
+
+<h3>THE PHILOSOPHER BOYLE.</h3>
+
+<p>After the death of Bacon, one of the most distinguished
+Englishmen was certainly Robert Boyle, who, if compared
+with his contemporaries, may be said to rank immediately
+below Newton, though of course very inferior to him as an original
+thinker. Boyle was the first who instituted exact experiments
+into the relation between colour and heat; and by
+this means not only ascertained some very important facts,
+but laid a foundation for that union between optics and thermotics,
+which, though not yet completed, now merely waits
+for some great philosopher to strike out a generalisation large
+enough to cover both, and thus fuse the two sciences into a
+single study. It is also to Boyle, more than to any other Englishman,
+that we owe the science of hydrostatics in the state<span class="pagenum"><a name="Page_7" id="Page_7">7</a></span>
+in which we now possess it.<a name="FNanchor_3" id="FNanchor_3" href="#Footnote_3" class="fnanchor">3</a> He is also the original discoverer
+of that beautiful law, so fertile in valuable results, according
+to which the elasticity of air varies as its density. And, in
+the opinion of one of the most eminent modern naturalists, it
+was Boyle who opened up those chemical inquiries which went
+on accumulating until, a century later, they supplied the
+means by which Lavoisier and his contemporaries fixed the
+real basis of chemistry, and enabled it for the first time to
+take its proper stand among those sciences that deal with the
+external world.&mdash;<i>Buckle’s History of Civilization</i>, vol. i.</p>
+
+<h3>SIR ISAAC NEWTON’S ROOMS AND LABORATORY IN TRINITY
+COLLEGE, CAMBRIDGE.</h3>
+
+<p>Of the rooms occupied by Newton during his early residence
+at Cambridge, it is now difficult to settle the locality.
+The chamber allotted to him as Fellow, in 1667, was “the
+Spiritual Chamber,” conjectured to have been the ground-room,
+next the chapel, but it is not certain that he resided
+there. The rooms in which he lived from 1682 till he left
+Cambridge, are in the north-east corner of the great court,
+on the first floor, on the right or north of the gateway or
+principal entrance to the college. His laboratory, as Dr.
+Humphrey Newton tell us, was “on the left end of the garden,
+near the east end of the chapel; and his telescope (refracting)
+was five feet long, and placed at the head of the stairs, going
+down into the garden.”<a name="FNanchor_4" id="FNanchor_4" href="#Footnote_4" class="fnanchor">4</a> The east side of Newton’s rooms has
+been altered within the last fifty years: Professor Sedgwick,
+who came up to college in 1804, recollects a wooden room,
+supported on an arcade, shown in Loggan’s view, in place of
+which arcade is now a wooden wall and brick chimney.</p>
+
+<blockquote>
+
+<p>Dr. Humphrey Newton relates that in college Sir Isaac very rarely
+went to bed till two or three o’clock in the morning, sometimes not till
+five or six, especially at spring and fall of the leaf, when he used to
+employ about six weeks in his laboratory, the fire scarcely going out
+either night or day; he sitting up one night, and Humphrey another,
+till he had finished his chemical experiments. Dr. Newton describes
+the laboratory as “well furnished with chymical materials, as bodyes,
+receivers, heads, crucibles, &amp;c., which was made very little use of, y<sup>e</sup>
+crucibles excepted, in which he fused his metals: he would sometimes,
+though very seldom, look into an old mouldy book, which lay in
+his laboratory; I think it was titled <i>Agricola de Metallis</i>, the transmuting
+of metals being his chief design, for which purpose antimony<span class="pagenum"><a name="Page_8" id="Page_8">8</a></span>
+was a great ingredient.” “His brick furnaces, <i>pro re nata</i>, he made
+and altered himself without troubling a bricklayer.” “What observations
+he might make with his telescope, I know not, but several of
+his observations about comets and the planets may be found scattered
+here and there in a book intitled <i>The Elements of Astronomy</i>, by Dr.
+David Gregory.”<a name="FNanchor_5" id="FNanchor_5" href="#Footnote_5" class="fnanchor">5</a></p></blockquote>
+
+<h3>NEWTON’S “APPLE-TREE.”</h3>
+
+<p>Curious and manifold as are the trees associated with the
+great names of their planters, or those who have sojourned in
+their shade, the Tree which, by the falling of its fruit, suggested
+to Newton the idea of Gravity, is of paramount interest.
+It appears that, in the autumn of 1665, Newton left his college
+at Cambridge for his paternal home at Woolsthorpe. “When
+sitting alone in the garden,” says Sir David Brewster, “and
+speculating on the power of gravity, it occurred to him, that as
+the same power by which the apple fell to the ground was not
+sensibly diminished at the greatest distance from the centre of
+the earth to which we can reach, neither at the summits of
+the loftiest spires, nor on the tops of the highest mountains,
+it might extend to the moon and retain her in her orbit, in
+the same manner as it bends into a curve a stone or a cannon-ball
+when projected in a straight line from the surface of the
+earth.”&mdash;<i>Life of Newton</i>, vol. i. p. 26. Sir David Brewster
+notes, that neither Pemberton nor Whiston, who received from
+Newton himself his first ideas of gravity, records this story of
+the falling apple. It was mentioned, however, to Voltaire by
+Catherine Barton, Newton’s niece; and to Mr. Green by Martin
+Folkes, President of the Royal Society. Sir David Brewster
+saw the reputed apple-tree in 1814, and brought away a portion
+of one of its roots. The tree was so much decayed that it was
+cut down in 1820, and the wood of it carefully preserved by
+Mr. Turnor, of Stoke Rocheford.</p>
+
+<p><span class="pagenum"><a name="Page_9" id="Page_9">9</a></span></p>
+
+<blockquote>
+
+<p>De Morgan (in <i>Notes and Queries</i>, 2d series, No. 139, p. 169) questions
+whether the fruit was an apple, and maintains that the anecdote
+rests upon very slight authority; more especially as the idea had for
+many years been floating before the minds of physical inquirers; although
+Newton cleared away the confusions and difficulties which prevented
+very able men from proceeding beyond conjecture, and by this
+means established <i>universal</i> gravitation.</p></blockquote>
+
+<h3>NEWTON’S “PRINCIPIA.”</h3>
+
+<p>“It may be justly said,” observes Halley, “that so many
+and so valuable philosophical truths as are herein discovered
+and put past dispute were never yet owing to the capacity and
+industry of any one man.” “The importance and generality
+of the discoveries,” says Laplace, “and the immense number
+of original and profound views, which have been the germ of
+the most brilliant theories of the philosophers of this (18th)
+century, and all presented with much elegance, will ensure to
+the work on the <i>Mathematical Principles of Natural Philosophy</i>
+a preëminence above all the other productions of human
+genius.”</p>
+
+<h3>DESCARTES’ LABOURS IN PHYSICS.</h3>
+
+<p>The most profound among the many eminent thinkers
+France has produced, is Réné Descartes, of whom the least
+that can be said is, that he effected a revolution more decisive
+than has ever been brought about by any other single mind;
+that he was the first who successfully applied algebra to geometry;
+that he pointed out the important law of the sines;
+that in an age in which optical instruments were extremely
+imperfect, he discovered the changes to which light is subjected
+in the eye by the crystalline lens; that he directed attention
+to the consequences resulting from the weight of the
+atmosphere; and that he moreover detected the causes of the
+rainbow. At the same time, and as if to combine the most
+varied forms of excellence, he is not only allowed to be the first
+geometrician of the age, but by the clearness and admirable
+precision of his style, he became one of the founders of French
+prose. And, although he was constantly engaged in those lofty
+inquiries into the nature of the human mind, which can never
+be studied without wonder, he combined with them a long
+course of laborious experiment upon the animal frame, which
+raised him to the highest rank among the anatomists of his
+time. The great discovery made by Harvey of the Circulation
+of the Blood was neglected by most of his contemporaries; but
+it was at once recognised by Descartes, who made it the basis
+of the physiological part of his work on man. He was likewise
+the discoverer of the lacteals by Aselli, which, like every great<span class="pagenum"><a name="Page_10" id="Page_10">10</a></span>
+truth yet laid before the world, was at its first appearance, not
+only disbelieved, but covered with ridicule.&mdash;<i>Buckle’s History
+of Civilization</i>, vol. i.</p>
+
+<h3>CONIC SECTIONS.</h3>
+
+<p>If a cone or sugar-loaf be cut through in certain directions,
+we shall obtain figures which are termed conic sections: thus,
+if we cut through a sugar-loaf parallel to its base or bottom,
+the outline or edge of the loaf where it is cut will be <i>a circle</i>.
+If the cut is made so as to slant, and not be parallel to the base
+of the loaf, the outline is an <i>ellipse</i>, provided the cut goes quite
+through the sides of the loaf all round; but if it goes slanting,
+and parallel to the line of the loaf’s side, the outline is a <i>parabola</i>,
+a conic section or curve, which is distinguished by characteristic
+properties, every point of it bearing a certain fixed relation
+to a certain point within it, as the circle does to its centre.&mdash;<i>Dr.
+Paris’s Notes to Philosophy in Sport, &amp;c.</i></p>
+
+<h3>POWER OF COMPUTATION.</h3>
+
+<p>The higher class of mathematicians, at the end of the seventeenth
+century, had become excellent computers, particularly
+in England, of which Wallis, Newton, Halley, the Gregorys, and
+De Moivre, are splendid examples. Before results of extreme
+exactness had become quite familiar, there was a gratifying
+sense of power in bringing out the new methods. Newton, in
+one of his letters to Oldenburg, says that he was at one time too
+much attached to such things, and that he should be ashamed
+to say to what number of figures he was in the habit of carrying
+his results. The growth of power of computation on the Continent
+did not, however, keep pace with that of the same in England.
+In 1696, De Laguy, a well-known writer on algebra, and
+a member of the Academy of Sciences, said that the most skilful
+computer could not, in less than a month, find within a unit
+the cube root of 696536483318640035073641037.&mdash;<i>De Morgan.</i></p>
+
+<h3>“THE SCIENCE OF THE COSMOS.”</h3>
+
+<p>Humboldt, characterises this “uncommon but definite expression”
+as the treating of “the assemblage of all things with
+which space is filled, from the remotest nebulæ to the climatic
+distribution of those delicate tissues of vegetable matter which
+spread a variegated covering over the surface of our rocks.”
+The word <i>cosmos</i>, which primitively, in the Homeric ages,
+indicated an idea of order and harmony, was subsequently
+adopted in scientific language, where it was gradually applied
+to the order observed in the movements of the heavenly bodies;
+to the whole universe; and then finally to the world in which
+this harmony was reflected to us.</p>
+
+<hr />
+
+<p><span class="pagenum"><a name="Page_11" id="Page_11">11</a></span></p>
+
+<div class="chapter"></div>
+<h2><a name="Physical" id="Physical"></a>Physical Phenomena.</h2>
+
+<h3>ALL THE WORLD IN MOTION.</h3>
+
+<p>Humboldt, in his <i>Cosmos</i>,<a name="FNanchor_6" id="FNanchor_6" href="#Footnote_6" class="fnanchor">6</a> gives the following beautiful illustrative
+proofs of this phenomenon:</p>
+
+<blockquote>
+
+<p>If, for a moment, we imagine the acuteness of our senses preternaturally
+heightened to the extreme limits of telescopic vision, and bring
+together events separated by wide intervals of time, the apparent repose
+which reigns in space will suddenly vanish; countless stars will be
+seen moving in groups in various directions; nebulæ wandering, condensing,
+and dissolving like cosmical clouds; the milky way breaking
+up in parts, and its veil rent asunder. In every point of the celestial
+vault we shall recognise the dominion of progressive movement, as on
+the surface of the earth where vegetation is constantly putting forth its
+leaves and buds, and unfolding its blossoms. The celebrated Spanish
+botanist, Cavanilles, first conceived the possibility of “seeing grass
+grow,” by placing the horizontal micrometer wire of a telescope, with a
+high magnifying power, at one time on the point of a bamboo shoot, and
+at another on the rapidly unfolding flowering stem of an American aloe;
+precisely as the astronomer places the cross of wires on a culminating
+star. Throughout the whole life of physical nature&mdash;in the organic as
+in the sidereal world&mdash;existence, preservation, production, and development,
+are alike associated with motion as their essential condition.</p></blockquote>
+
+<h3>THE AXIS OF ROTATION.</h3>
+
+<p>It is remarkable as a mechanical fact, that nothing is so permanent
+in nature as the Axis of Rotation of any thing which is
+rapidly whirled. We have examples of this in every-day practice.
+The first is the motion of <i>a boy’s hoop</i>. What keeps the
+hoop from falling?&mdash;It is its rotation, which is one of the most
+complicated subjects in mechanics.</p>
+
+<p>Another thing pertinent to this question is, <i>the motion of a
+quoit</i>. Every body who ever threw a quoit knows that to make
+it preserve its position as it goes through the air, it is necessary
+to give it a whirling motion. It will be seen that while whirling,
+it preserves its plane, whatever the position of the plane
+may be, and however it may be inclined to the direction in
+which the quoit travels. Now, this has greater analogy with
+the motion of the earth than any thing else.</p>
+
+<p>Another illustration is <i>the motion of a spinning top</i>. The
+greatest mathematician of the last century, the celebrated
+Euler, has written a whole book on the motion of a top, and
+his Latin treatise <i>De motu Turbinis</i> is one of the most remarkable
+books on mechanics. The motion of a top is a matter of<span class="pagenum"><a name="Page_12" id="Page_12">12</a></span>
+the greatest importance; it is applicable to the elucidation of
+some of the greatest phenomena of nature. In all these instances
+there is this wonderful tendency in rotation to preserve
+the axis of rotation unaltered.&mdash;<i>Prof. Airy’s Lect. on Astronomy.</i></p>
+
+<h3>THE EARTH’S ANNUAL MOTION.</h3>
+
+<p>In conformity with the Copernican view of our system, we
+must learn to look upon the sun as the comparatively motionless
+centre about which the earth performs an annual elliptic
+orbit of the dimensions and excentricity, and with a velocity,
+regulated according to a certain assigned law; the sun occupying
+one of the foci of the ellipse, and from that station quietly
+disseminating on all sides its light and heat; while the earth
+travelling round it, and presenting itself differently to it at different
+times of the year and day, passes through the varieties of
+day and night, summer and winter, which we enjoy.&mdash;<i>Sir John
+Herschel’s Outlines of Astronomy.</i></p>
+
+<p>Laplace has shown that the length of the day has not varied
+the hundredth part of a second since the observations of Hipparchus,
+2000 years ago.</p>
+
+<h3>STABILITY OF THE OCEAN.</h3>
+
+<p>In submitting this question to analysis, Laplace found that
+the <i>equilibrium of the ocean is stable if its density is less than the
+mean density of the earth</i>, and that its equilibrium cannot be subverted
+unless these two densities are equal, or that of the earth
+less than that of its waters. The experiments on the attraction
+of Schehallien and Mont Cenis, and those made by Cavendish,
+Reich, and Baily, with balls of lead, demonstrate that the mean
+density of the earth is at least <i>five</i> times that of water, and hence
+the stability of the ocean is placed beyond a doubt. As the seas,
+therefore, have at one time covered continents which are now
+raised above their level, we must seek for some other cause of
+it than any want of stability in the equilibrium of the ocean.
+How beautifully does this conclusion illustrate the language of
+Scripture, “Hitherto shalt thou come, but no further”! (<i>Job</i>
+xxxviii. 11.)</p>
+
+<h3>COMPRESSION OF BODIES.</h3>
+
+<p>Sir John Leslie observes, that <i>air compressed</i> into the fiftieth
+part of its volume has its elasticity fifty times augmented: if it
+continued to contract at that rate, it would, from its own incumbent
+weight, acquire the density of water at the depth of
+thirty-four miles. But water itself would have its density
+doubled at the depth of ninety-three miles, and would attain the
+density of quicksilver at the depth of 362 miles. In descending,
+therefore, towards the centre, through nearly 4000 miles, the
+condensation of ordinary substances would surpass the utmost<span class="pagenum"><a name="Page_13" id="Page_13">13</a></span>
+powers of conception. Dr. Young says, that steel would be
+compressed into one-fourth, and stone into one-eighth, of its
+bulk at the earth’s centre.&mdash;<i>Mrs. Somerville.</i></p>
+
+<h3>THE WORLD IN A NUTSHELL.</h3>
+
+<p>From the many proofs of the non-contact of the atoms, even
+in the most solid parts of bodies; from the very great space
+obviously occupied by pores&mdash;the mass having often no more
+solidity than a heap of empty boxes, of which the apparently
+solid parts may still be as porous in a second degree and so on;
+and from the great readiness with which light passes in all directions
+through dense bodies, like glass, rock-crystal, diamond,
+&amp;c., it has been argued that there is so exceedingly little of
+really solid matter even in the densest mass, that <i>the whole
+world</i>, if the atoms could be brought into absolute contact,
+<i>might be compressed into a nutshell</i>. We have as yet no means
+of determining exactly what relation this idea has to truth.&mdash;<i>Arnott.</i></p>
+
+<h3>THE WORLD OF ATOMS.</h3>
+
+<p>The infinite groups of atoms flying through all time and
+space, in different directions and under different laws, have
+interchangeably tried and exhibited every possible mode of rencounter:
+sometimes repelled from each other by concussion;
+and sometimes adhering to each other from their own jagged
+or pointed construction, or from the casual interstices which
+two or more connected atoms must produce, and which may be
+just adapted to those of other figures,&mdash;as globular, oval, or
+square. Hence the origin of compound and visible bodies;
+hence the origin of large masses of matter; hence, eventually,
+the origin of the world.&mdash;<i>Dr. Good’s Book of Nature.</i></p>
+
+<p>The great Epicurus speculated on “the plastic nature” of
+atoms, and attributed to this <i>nature</i> the power they possess of
+arranging themselves into symmetric forms. Modern philosophers
+satisfy themselves with attraction; and reasoning from
+analogy, imagine that each atom has a polar system.&mdash;<i>Hunt’s
+Poetry of Science.</i></p>
+
+<h3>MINUTE ATOMS OF THE ELEMENTS: DIVISIBILITY OF MATTER.</h3>
+
+<p>So minute are the parts of the elementary bodies in their
+ultimate state of division, in which condition they are usually
+termed <i>atoms</i>, as to elude all our powers of inspection, even
+when aided by the most powerful microscopes. Who can see the
+particles of gold in a solution of that metal in <i>aqua regia</i>, or
+those of common salt when dissolved in water? Dr. Thomas
+Thomson has estimated the bulk of an ultimate particle or
+atom of lead as less than 1/888492000000000th of a cubic inch,<span class="pagenum"><a name="Page_14" id="Page_14">14</a></span>
+and concludes that its weight cannot exceed the 1/310000000000th
+of a grain.</p>
+
+<p>This curious calculation was made by Dr. Thomson, in order
+to show to what degree Matter could be divided, and still
+be sensible to the eye. He dissolved a grain of nitrate of lead
+in 500,000 grains of water, and passed through the solution
+a current of sulphuretted hydrogen; when the whole liquid
+became sensibly discoloured. Now, a grain of water may
+be regarded as being almost equal to a drop of that liquid,
+and a drop may be easily spread out so as to cover a square
+inch of surface. But under an ordinary microscope the millionth
+of a square inch may be distinguished by the eye. The
+water, therefore, could be divided into 500,000,000,000 parts.
+But the lead in a grain of nitrate of lead weighs 0·62 of a
+grain; an atom of lead, accordingly, cannot weigh more than
+1/810000000000th of a grain; while the atom of sulphur,
+which in combination with the lead rendered it visible, could
+not weigh more than 1/2015000000000, that is, the two-billionth
+part of a grain.&mdash;<i>Professor Low</i>; <i>Jameson’s Journal</i>, No. 106.</p>
+
+<h3>WEIGHT OF AIR.</h3>
+
+<p>Air can be so rarefied that the contents of a cubic foot shall
+not weigh the tenth part of a grain: if a quantity that would
+fill a space the hundredth part of an inch in diameter be separated
+from the rest, the air will still be found there, and we
+may reasonably conceive that there may be several particles
+present, though the weight is less than the seventeen-hundred-millionth
+of a grain.</p>
+
+<h3>DURATION OF THE PYRAMID.</h3>
+
+<p>The great reason of the duration of the pyramid above all
+other forms is, that it is most fitted to resist the force of gravitation.
+Thus the Pyramids of Egypt are the oldest monuments
+in the world.</p>
+
+<h3>INERTIA ILLUSTRATED.</h3>
+
+<p>Many things of common occurrence (says Professor Tyndall)
+are to be explained by reference to the quality of inactivity.
+We will here state a few of them.</p>
+
+<p>When a railway train is moving, if it strike against any obstacle
+which arrests its motion, the passengers are thrown
+forward in the direction in which the train was proceeding.
+Such accidents often occur on a small scale, in attaching carriages
+at railway stations. The reason is, that the passengers
+share the motion of the train, and, as matter, they tend to
+persist in motion. When the train is suddenly checked, this
+tendency exhibits itself by the falling forward referred to. In<span class="pagenum"><a name="Page_15" id="Page_15">15</a></span>
+like manner, when a train previously at rest is suddenly set in
+motion, the tendency of the passengers to remain at rest evinces
+itself by their falling in a direction opposed to that in which
+the train moves.</p>
+
+<h3>THE LEANING TOWER OF PISA.<a name="FNanchor_7" id="FNanchor_7" href="#Footnote_7" class="fnanchor">7</a></h3>
+
+<p>Sir John Leslie used to attribute the stability of this tower
+to the cohesion of the mortar it is built with being sufficient to
+maintain it erect, in spite of its being out of the condition required
+by physics&mdash;to wit, that “in order that a column shall
+stand, a perpendicular let fall from the centre of gravity must
+fall within the base.” Sir John describes the Tower of Pisa to
+be in violation of this principle; but, according to later authorities,
+the perpendicular falls within the base.</p>
+
+<h3>EARLY PRESENTIMENTS OF CENTRIFUGAL FORCES.</h3>
+
+<p>Jacobi, in his researches on the mathematical knowledge of
+the Greeks, comments on “the profound consideration of nature
+evinced by Anaxagoras, in whom we read with astonishment a
+passage asserting that the moon, if the centrifugal force were
+intermitted, would fall to the earth like a stone from a sling.”
+Anaxagoras likewise applied the same theory of “falling where
+the force of rotation had been intermitted” to all the material
+celestial bodies. In Aristotle and Simplicius may also be
+traced the idea of “the non-falling of heavenly bodies when
+the rotatory force predominates over the actual falling force,
+or downward attraction;” and Simplicius mentions that “water
+in a phial is not spilt when the movement of rotation is
+more rapid than the downward movement of the water.” This
+is illustrated at the present day by rapidly whirling a pail half-filled
+with water without spilling a drop.</p>
+
+<p>Plato had a clearer idea than Aristotle of the <i>attractive force</i>
+exercised by the earth’s centre on all heavy bodies removed
+from it; for he was acquainted with the acceleration of falling<span class="pagenum"><a name="Page_16" id="Page_16">16</a></span>
+bodies, although he did not correctly understand the cause.
+John Philoponus, the Alexandrian, probably in the sixth century,
+was the first who ascribed the movement of the heavenly
+bodies to a primitive impulse, connecting with this idea that
+of the fall of bodies, or the tendency of all substances, whether
+heavy or light, to reach the ground. The idea conceived by
+Copernicus, and more clearly expressed by Kepler, who even
+applied it to the ebb and flow of the ocean, received in 1666
+and 1674 a new impulse from Robert Hooke; and next Newton’s
+theory of gravitation presented the grand means of converting
+the whole of physical astronomy into a true <i>mechanism
+of the heavens</i>.</p>
+
+<p>The law of gravitation knows no exception; it accounts accurately
+for the most complex motions of the members of our
+own system; nay more, the paths of double stars, far removed
+from all appreciable effects of our portion of the universe, are
+in perfect accordance with its theory.<a name="FNanchor_8" id="FNanchor_8" href="#Footnote_8" class="fnanchor">8</a></p>
+
+<h3>HEIGHT OF FALLS.</h3>
+
+<p>The fancy of the Greeks delighted itself in wild visions of the
+height of falls. In Hesiod’s <i>Theogony</i> it is said, speaking of the
+fall of the Titans into Tartarus, “if a brazen anvil were to fall
+from heaven nine days and nine nights long, it would reach
+the earth on the tenth.” This descent of the anvil in 777,600
+seconds of time gives an equivalent in distance of 309,424 geographical
+miles (allowance being made, according to Galle’s
+calculation, for the considerable diminution in force of attraction
+at planetary distances); therefore 1½ times the distance
+of the moon from the earth. But, according to the <i>Iliad</i>, Hephæstus
+fell down to Lemnos in one day; “when but a little
+breath was still in him.”&mdash;<i>Note to Humboldt’s Cosmos</i>, vol. iii.</p>
+
+<h3>RATE OF THE FALL OF BODIES.</h3>
+
+<p>A body falls in gravity precisely 16-1/16 feet in a second, and
+the velocity increases according to the squares of the time, viz.:</p>
+
+<table summary="Rate of the fall of bodies">
+  <tr>
+    <td class="tdl">In ¼ (quarter of a second) a body falls</td>
+    <td class="tdr">1</td>
+    <td class="tdc">foot.</td></tr>
+  <tr>
+    <td class="tdl int16">½ (half a second)</td>
+    <td class="tdr">4</td>
+    <td class="tdc">feet.</td></tr>
+  <tr>
+    <td class="tdl int16">1 second</td>
+    <td class="tdr">16</td>
+    <td class="tdc">”</td></tr>
+  <tr>
+    <td class="tdl int16">2 ditto</td>
+    <td class="tdr">64</td>
+    <td class="tdc">”</td></tr>
+  <tr>
+    <td class="tdl int16">3 ditto</td>
+    <td class="tdr">144</td>
+    <td class="tdc">”</td></tr>
+</table>
+
+<p><span class="pagenum"><a name="Page_17" id="Page_17">17</a></span>
+The power of gravity at two miles distance from the earth is
+four times less than at one mile; at three miles nine times
+less, and so on. It goes on lessening, but is never destroyed.&mdash;<i>Notes
+in various Sciences.</i></p>
+
+<h3>VARIETIES OF SPEED.</h3>
+
+<p>A French scientific work states the ordinary rate to be:</p>
+
+<table summary="Varieties of speed">
+  <tr class="smaller">
+    <td> </td>
+    <td class="tdc" colspan="2">per second.</td></tr>
+  <tr>
+    <td class="tdl">Of a man walking</td>
+    <td class="tdr">4</td>
+    <td class="tdc">feet.</td></tr>
+  <tr>
+    <td class="tdl">Of a good horse in harness</td>
+    <td class="tdr">12</td>
+    <td class="tdc">”</td></tr>
+  <tr>
+    <td class="tdl">Of a rein-deer in a sledge on the ice</td>
+    <td class="tdr">26</td>
+    <td class="tdc">”</td></tr>
+  <tr>
+    <td class="tdl">Of an English race-horse</td>
+    <td class="tdr">43</td>
+    <td class="tdc">”</td></tr>
+  <tr>
+    <td class="tdl">Of a hare</td>
+    <td class="tdr">88</td>
+    <td class="tdc">”</td></tr>
+  <tr>
+    <td class="tdl">Of a good sailing ship</td>
+    <td class="tdr">19</td>
+    <td class="tdc">”</td></tr>
+  <tr>
+    <td class="tdl">Of the wind</td>
+    <td class="tdr">82</td>
+    <td class="tdc">”</td></tr>
+  <tr>
+    <td class="tdl">Of sound</td>
+    <td class="tdr">1038</td>
+    <td class="tdc">”</td></tr>
+  <tr>
+    <td class="tdl">Of a 24-pounder cannon-ball</td>
+    <td class="tdr">1300</td>
+    <td class="tdc">”</td></tr>
+</table>
+
+<h3>LIFTING HEAVY PERSONS.</h3>
+
+<p>One of the most extraordinary pages in Sir David Brewster’s
+<i>Letters on Natural Magic</i> is the experiment in which a heavy
+man is raised with the greatest facility when he is lifted up the
+instant that his own lungs, and those of the persons who raise
+him, are inflated with air. Thus the heaviest person in the
+party lies down upon two chairs, his legs being supported by
+the one and his back by the other. Four persons, one at each
+leg, and one at each shoulder, then try to raise him&mdash;the person
+to be raised giving two signals, by clapping his hands. At
+the first signal, he himself and the four lifters begin to draw a
+long and full breath; and when the inhalation is completed, or
+the lungs filled, the second signal is given for raising the person
+from the chair. To his own surprise, and that of his bearers,
+he rises with the greatest facility, as if he were no heavier than
+a feather. Sir David Brewster states that he has seen this
+inexplicable experiment performed more than once; and he
+appealed for testimony to Sir Walter Scott, who had repeatedly
+seen the experiment, and performed the part both of the load
+and of the bearer. It was first shown in England by Major H.,
+who saw it performed in a large party at Venice, under the direction
+of an officer of the American navy.<a name="FNanchor_9" id="FNanchor_9" href="#Footnote_9" class="fnanchor">9</a></p>
+
+<p>Sir David Brewster (in a letter to <i>Notes and Queries</i>, No. 143)
+further remarks, that “the inhalation of the lifters the moment
+the effort is made is doubtless essential, and for this reason:
+when we make a great effort, either in pulling or lifting, we
+always fill the chest with air previous to the effort; and when<span class="pagenum"><a name="Page_18" id="Page_18">18</a></span>
+the inhalation is completed, we close the <i>rima glottidis</i> to keep
+the air in the lungs. The chest being thus kept expanded, the
+pulling or lifting muscles have received as it were a fulcrum
+round which their power is exerted; and we can thus lift the
+greatest weight which the muscles are capable of doing. When
+the chest collapses by the escape of the air, the lifters lose their
+muscular power; reinhalation of air by the liftee can certainly
+add nothing to the power of the lifters, or diminish his own
+weight, which is only increased by the weight of the air which
+he inhales.”</p>
+
+<h3>“FORCE CAN NEITHER BE CREATED NOR DESTROYED.”</h3>
+
+<p>Professor Faraday, in his able inquiry upon “the Conservation
+of Force,” maintains that to admit that force may be destructible,
+or can altogether disappear, would be to admit that
+matter could be uncreated; for we know matter only by its
+forces. From his many illustrations we select the following:</p>
+
+<blockquote>
+
+<p>The indestructibility of individual matter is a most important case of
+the Conservation of Chemical Force. A molecule has been endowed with
+powers which give rise in it to various qualities; and those never change,
+either in their nature or amount. A particle of oxygen is ever a particle
+of oxygen; nothing can in the least wear it. If it enters into combination,
+and disappears as oxygen; if it pass through a thousand combinations&mdash;animal,
+vegetable, mineral; if it lie hid for a thousand years, and
+then be evolved,&mdash;it is oxygen with the first qualities, neither more nor
+less. It has all its original force, and only that; the amount of force
+which it disengaged when hiding itself, has again to be employed in a
+reverse direction when it is set at liberty: and if, hereafter, we should
+decompose oxygen, and find it compounded of other particles, we should
+only increase the strength of the proof of the conservation of force; for
+we should have a right to say of these particles, long as they have been
+hidden, all that we could say of the oxygen itself.</p></blockquote>
+
+<p>In conclusion, he adds:</p>
+
+<blockquote>
+
+<p>Let us not admit the destruction or creation of force without clear
+and constant proof. Just as the chemist owes all the perfection of his
+science to his dependence on the certainty of gravitation applied by the
+balance, so may the physical philosopher expect to find the greatest
+security and the utmost aid in the principle of the conservation of force.
+All that we have that is good and safe&mdash;as the steam-engine, the electric
+telegraph, &amp;c.&mdash;witness to that principle; it would require a perpetual
+motion, a fire without heat, heat without a source, action without reaction,
+cause without effect, or effect without cause, to displace it from
+its rank as a law of nature.</p></blockquote>
+
+<h3>NOTHING LOST IN THE MATERIAL WORLD.</h3>
+
+<p>“It is remarkable,” says Kobell in his <i>Mineral Kingdom</i>,
+“how a change of place, a circulation as it were, is appointed
+for the inanimate or naturally immovable things upon the earth;
+and how new conditions, new creations, are continually developing
+themselves in this way. I will not enter here into the<span class="pagenum"><a name="Page_19" id="Page_19">19</a></span>
+evaporation of water, for instance from the widely-spreading
+ocean; how the clouds produced by this pass over into foreign
+lands and then fall again to the earth as rain, and how this
+wandering water is, partly at least, carried along new journeys,
+returning after various voyages to its original home: the mere
+mechanical phenomena, such as the transfer of seeds by the
+winds or by birds, or the decomposition of the surface of the
+earth by the friction of the elements, suffice to illustrate this.”</p>
+
+<h3>TIME AN ELEMENT OF FORCE.</h3>
+
+<p>Professor Faraday observes that Time is growing up daily
+into importance as an element in the exercise of Force, which
+he thus strikingly illustrates:</p>
+
+<blockquote>
+
+<p>The earth moves in its orbit of time; the crust of the earth moves in
+time; light moves in time; an electro-magnet requires time for its charge
+by an electric current: to inquire, therefore, whether power, acting either
+at sensible or insensible distances, always acts in <i>time</i>, is not to be metaphysical;
+if it acts in time and across space, it must act by physical
+lines of force; and our view of the nature of force may be affected to
+the extremest degree by the conclusions which experiment and observation
+on time may supply, being perhaps finally determinable only by
+them. To inquire after the possible time in which gravitating, magnetic,
+or electric force is exerted, is no more metaphysical than to mark the
+times of the hands of a clock in their progress; or that of the temple of
+Serapis, and its ascents and descents; or the periods of the occultation
+of Jupiter’s satellites; or that in which the light comes from them to
+the earth. Again, in some of the known cases of the action of time
+something happens while <i>the time</i> is passing which did not happen before,
+and does not continue after; it is therefore not metaphysical to
+expect an effect in <i>every</i> case, or to endeavour to discover its existence
+and determine its nature.</p></blockquote>
+
+<h3>CALCULATION OF HEIGHTS AND DISTANCES.</h3>
+
+<p>By the assistance of a seconds watch the following interesting
+calculations may be made:</p>
+
+<blockquote>
+
+<p>If a traveller, when on a precipice or on the top of a building, wish
+to ascertain the height, he should drop a stone, or any other substance
+sufficiently heavy not to be impeded by the resistance of the atmosphere;
+and the number of seconds which elapse before it reaches the bottom,
+carefully noted on a seconds watch, will give the height. For the stone
+will fall through the space of 16-1/8 feet during the first second, and will
+increase in rapidity as the square of the time employed in the fall: if,
+therefore, 16-1/8 be multiplied by the number of seconds the stone has
+taken to fall, this product also multiplied by the same number of seconds
+will give the height. Suppose the stone takes five seconds to reach the
+bottom:</p>
+
+<p class="center">
+16-1/8 × 5 = 80-5/8 × 5 = 403-1/8, height of the precipice.
+</p>
+
+<p>The Count Xavier de Maistre, in his <i>Expédition nocturne autour de
+ma Chambre</i>, anxious to ascertain the exact height of his room from the
+ground on which Turin is built, tells us he proceeded as follows: “My
+heart beat quickly, and I just counted three pulsations from the instant<span class="pagenum"><a name="Page_20" id="Page_20">20</a></span>
+I dropped my slipper until I heard the sound as it fell in the street,
+which, according to the calculations made of the time taken by bodies
+in their accelerated fall, and of that employed by the sonorous undulations
+of the air to arrive from the street to my ear, gave the height of
+my apartment as 94 feet 3 inches 1 tenth (French measure), supposing
+that my heart, agitated as it was, beat 120 times in a minute.”</p>
+
+<p>A person travelling may ascertain his rate of walking by the aid of a
+slight string with a piece of lead at one end, and the use of a seconds
+watch; the string being knotted at distances of 44 feet, the 120th part
+of an English mile, and bearing the same proportion to a mile that half
+a minute bears to an hour. If the traveller, when going at his usual
+rate, drops the lead, and suffers the string to slip through his hand, the
+number of knots which pass in half a minute indicate the number of
+miles he walks in an hour. This contrivance is similar to a <i>log-line</i> for
+ascertaining a ship’s rate at sea: the lead is enclosed in wood (whence
+the name <i>log</i>), that it may float, and the divisions, which are called
+<i>knots</i>, are measured for nautical miles. Thus, if ten knots are passed in
+half a minute, they show that the vessel is sailing at the rate of ten knots,
+or miles, an hour: a seconds watch would here be of great service, but
+the half-minute sand-glass is in general use.</p>
+
+<p>The rapidity of a river may be ascertained by throwing in a light
+floating substance, which, if not agitated by the wind, will move with
+the same celerity as the water: the distance it floats in a certain number
+of seconds will give the rapidity of the stream; and this indicates the
+height of its source, the nature of its bottom, &amp;c.&mdash;See <i>Sir Howard
+Douglas on Bridges</i>. <i>Thomson’s Time and Time-keepers.</i></p></blockquote>
+
+<h3>SAND IN THE HOUR-GLASS.</h3>
+
+<p>It is a noteworthy fact, that the flow of Sand in the Hour-glass
+is perfectly equable, whatever may be the quantity in the
+glass; that is, the sand runs no faster when the upper half of
+the glass is quite full than when it is nearly empty. It would,
+however, be natural enough to conclude, that when full of sand
+it would be more swiftly urged through the aperture than when
+the glass was only a quarter full, and near the close of the hour.</p>
+
+<p>The fact of the even flow of sand may be proved by a very
+simple experiment. Provide some silver sand, dry it over or
+before the fire, and pass it through a tolerably fine sieve. Then
+take a tube, of any length or diameter, closed at one end, in
+which make a small hole, say the eighth of an inch; stop this
+with a peg, and fill up the tube with the sifted sand. Hold the
+tube steadily, or fix it to a wall or frame at any height from a
+table; remove the peg, and permit the sand to flow in any measure
+for any given time, and note the quantity. Then let the
+tube be emptied, and only half or a quarter filled with sand;
+measure again for a like time, and the same quantity of sand
+will flow: even if you press the sand in the tube with a ruler
+or stick, the flow of the sand through the hole will not be increased.</p>
+
+<p>The above is explained by the fact, that when the sand is
+poured into the tube, it fills it with a succession of conical<span class="pagenum"><a name="Page_21" id="Page_21">21</a></span>
+heaps; and that all the weight which the bottom of the tube
+sustains is only that of the heap which <i>first</i> falls upon it, as
+the succeeding heaps do not press downward, but only against
+the sides or walls of the tube.</p>
+
+<h3>FIGURE OF THE EARTH.</h3>
+
+<p>By means of a purely astronomical determination, based
+upon the action which the earth exerts on the motion of the
+moon, or, in other words, on the inequalities in lunar longitudes
+and latitudes, Laplace has shown in one single result the
+mean Figure of the Earth.</p>
+
+<blockquote>
+
+<p>It is very remarkable that an astronomer, without leaving his observatory,
+may, merely by comparing his observations with mean analytical
+results, not only be enabled to determine with exactness the size and
+degree of ellipticity of the earth, but also its distance from the sun and
+moon; results that otherwise could only be arrived at by long and arduous
+expeditions to the most remote parts of both hemispheres. The
+moon may therefore, by the observation of its movements, render appreciable
+to the higher departments of astronomy the ellipticity of the
+earth, as it taught the early astronomers the rotundity of our earth by
+means of its eclipses.&mdash;<i>Laplace’s Expos. du Syst. du Monde.</i></p></blockquote>
+
+<h3>HOW TO ASCERTAIN THE EARTH’S MAGNITUDE.</h3>
+
+<p>Sir John Herschel gives the following means of approximation.
+It appears by observation that two points, each ten feet
+above the surface, cease to be visible from each other over still
+water, and, in average atmospheric circumstances, at a distance
+of about eight miles. But 10 feet is the 528th part of a mile;
+so that half their distance, or four miles, is to the height of
+each as 4 × 528, or 2112:1, and therefore in the same proportion
+to four miles is the length of the earth’s diameter. It
+must, therefore, be equal to 4 × 2112 = 8448, or in round numbers,
+about 8000 miles, which is not very far from the truth.</p>
+
+<blockquote>
+
+<p>The excess is, however, about 100 miles, or 1/80th part. As convenient
+numbers to remember, the reader may bear in mind, that in our latitude
+there are just as many thousands of feet in a degree of the meridian as
+there are days in the year (365); that, speaking loosely, a degree is
+about seventy British statute miles, and a second about 100 feet; that
+the equatorial circumference of the earth is a little less than 25,000
+miles (24,899), and the ellipticity or polar flattening amounts to 1/300th
+part of the diameter.&mdash;<i>Outlines of Astronomy.</i></p></blockquote>
+
+<h3>MASS AND DENSITY OF THE EARTH.</h3>
+
+<p>With regard to the determination of the Mass and Density
+of the Earth by direct experiment, we have, in addition to the
+deviations of the pendulum produced by mountain masses, the
+variation of the same instruments when placed in a mine 1200
+feet in depth. The most recent experiments were conducted<span class="pagenum"><a name="Page_22" id="Page_22">22</a></span>
+by Professor Airy, in the Harton coal-pit, near South Shields:<a name="FNanchor_10" id="FNanchor_10" href="#Footnote_10" class="fnanchor">10</a>
+the oscillations of the pendulum at the bottom of the pit were
+compared with those of a clock above; the beats of the clock
+were transferred below for comparison by an electrio wire; and
+it was thus determined that a pendulum vibrating seconds at the
+mouth of the pit would gain 2¼ seconds per day at its bottom.
+The final result of the calculations depending on this experiment,
+which were published in the <i>Philosophical Transactions</i> of 1856,
+gives 6·565 for the mean density of the earth. The celebrated
+Cavendish experiment, by means of which the density of the
+earth was determined by observing the attraction of leaden
+balls on each other, has been repeated in a manner exhibiting
+an astonishing amount of skill and patience by the late Mr. F.
+Baily.<a name="FNanchor_11" id="FNanchor_11" href="#Footnote_11" class="fnanchor">11</a> The result of these experiments, combined with those
+previously made, gives as a mean result 5·441 as the earth’s
+density, when compared with water; thus confirming one of
+Newton’s astonishing divinations, that the mean density of the
+earth would be found to be between five and six times that of
+water.</p>
+
+<blockquote>
+
+<p>Humboldt is, however, of opinion that “we know only the mass of
+the whole earth and its mean density by comparing it with the open
+strata, which alone are accessible to us. In the interior of the earth,
+where all knowledge of its chemical and mineralogical character fails,
+we are limited to as pure conjecture as in the remotest bodies that
+revolve round the sun. We can determine nothing with certainty regarding
+the depth at which the geological strata must be supposed to
+be in a state of softening or of liquid fusion, of the condition of fluids
+when heated under an enormous pressure, or of the law of the increase
+of density from the upper surface to the centre of the earth.”&mdash;<i>Cosmos</i>,
+vol. i.</p></blockquote>
+
+<p>In M. Foucault’s beautiful experiment, by means of the
+vibration of a long pendulum, consisting of a heavy mass of
+metal suspended by a long wire from a strong fixed support, is
+demonstrated to the eye the rotation of the earth. The Gyroscope
+of the same philosopher is regarded not as a mere philosophical
+toy; but the principles of dynamics, by means of
+which it is made to demonstrate the earth’s rotation on its own
+axis, are explained with the greatest clearness. Thus the ingenuity
+of M. Foucault, combined with a profound knowledge of
+mechanics, has obtained proofs of one of the most interesting
+problems of astronomy from an unsuspected source.</p>
+
+<h3>THE EARTH AND MAN COMPARED.</h3>
+
+<p>The Earth&mdash;speaking roundly&mdash;is 8000 miles in diameter;<span class="pagenum"><a name="Page_23" id="Page_23">23</a></span>
+the atmosphere is calculated to be fifty miles in altitude; the
+loftiest mountain peak is estimated at five miles above the level
+of the sea, for this height has never been visited by man; the
+deepest mine that he has formed is 1650 feet; and his own
+stature does not average six feet. Therefore, if it were possible
+for him to construct a globe 800 feet&mdash;or twice the height of
+St. Paul’s Cathedral&mdash;in diameter, and to place upon any one
+point of its surface an atom of 1/4380th of an inch in diameter,
+and 1/720th of an inch in height, it would correctly denote the
+proportion that man bears to the earth upon which he moves.</p>
+
+<blockquote>
+
+<p>When by measurements, in which the evidence of the method advances
+equally with the precision of the results, the volume of the earth
+is reduced to the millionth part of the volume of the sun; when the sun
+himself, transported to the region of the stars, takes up a very modest
+place among the thousands of millions of those bodies that the telescope
+has revealed to us; when the 38,000,000 of leagues which separate the
+earth from the sun have become, by reason of their comparative smallness,
+a base totally insufficient for ascertaining the dimensions of the
+visible universe; when even the swiftness of the luminous rays (77,000
+leagues per second) barely suffices for the common valuations of science;
+when, in short, by a chain of irresistible proofs, certain stars have retired
+to distances that light could not traverse in less than a million of
+years;&mdash;we feel as if annihilated by such immensities. In assigning to
+man and to the planet that he inhabits so small a position in the material
+world, astronomy seems really to have made progress only to
+humble us.&mdash;<i>Arago.</i></p></blockquote>
+
+<h3>MEAN TEMPERATURE OF THE EARTH’S SURFACE.</h3>
+
+<p>Professor Dove has shown, by taking at all seasons the
+mean of the temperature of points diametrically opposite to
+each other, that the mean temperature <i>of the whole earth’s surface</i>
+in June considerably exceeds that in December. This result,
+which is at variance with the greater proximity of the
+sun in December, is, however, due to a totally different and
+very powerful cause,&mdash;the greater amount of land in that
+hemisphere which has its summer solstice in June (<i>i. e.</i> the
+northern); and the fact is so explained by him. The effect of
+land under sunshine is to throw heat into the general atmosphere,
+and to distribute it by the carrying power of the latter
+over the whole earth. Water is much less effective in this
+respect, the heat penetrating its depths and being there absorbed;
+so that the surface never acquires a very elevated
+temperature, even under the equator.&mdash;<i>Sir John Herschel’s
+Outlines.</i></p>
+
+<h3>TEMPERATURE OF THE EARTH STATIONARY.</h3>
+
+<p>Although, according to Bessel, 25,000 cubic miles of water
+flow in every six hours from one quarter of the earth to another,
+and the temperature is augmented by the ebb and flow of every<span class="pagenum"><a name="Page_24" id="Page_24">24</a></span>
+tide, all that we know with certainty is, that the <i>resultant
+effect</i> of all the thermal agencies to which the earth is exposed
+has undergone no perceptible change within the historic period.
+We owe this fine deduction to Arago. In order that the <i>date
+palm</i> should ripen its fruit, the mean temperature of the place
+must exceed 70 deg. Fahr.; and, on the other hand, the <i>vine</i>
+cannot be cultivated successfully when the temperature is
+72 deg. or upwards. Hence the mean temperature of any
+place at which these two plants flourished and bore fruit must
+lie between these narrow limits, <i>i. e.</i> could not differ from
+71 deg. Fahr. by more than a single degree. Now from the
+Bible we learn that both plants were <i>simultaneously</i> cultivated
+in the central valleys of Palestine in the time of Moses; and
+its then temperature is thus definitively determined. It is the
+same at the present time; so that the mean temperature of
+this portion of the globe has not sensibly altered in the course
+of thirty-three centuries.</p>
+
+<h3>THEORY OF CRYSTALLISATION.</h3>
+
+<p>Professor Plücker has ascertained that certain crystals, in
+particular the cyanite, “point very well to the north by the
+magnetic power of the earth only. It is a true compass-needle;
+and more than that, you may obtain its declination.” Upon
+this Mr. Hunt remarks: “We must remember that this crystal,
+the cyanite, is a compound of silica and alumina only. This
+is the amount of experimental evidence which science has
+afforded in explanation of the conditions under which nature
+pursues her wondrous work of crystal formation. We see just
+sufficient of the operation to be convinced that the luminous
+star which shines in the brightness of heaven, and the cavern-secreted
+gem, are equally the result of forces which are known
+to us in only a few of their modifications.”&mdash;<i>Poetry of Science.</i></p>
+
+<p>Gay Lussac first made the remark, that a crystal of potash-alum,
+transferred to a solution of ammonia-alum, continued to
+increase without its form being modified, and might thus be
+covered with alternate layers of the two alums, preserving its
+regularity and proper crystalline figure. M. Beudant afterwards
+observed that other bodies, such as the sulphates of iron
+and copper, might present themselves in crystals of the same
+form and angles, although the form was not a simple one, like
+that of alum. But M. Mitscherlich first recognised this correspondence
+in a sufficient number of cases to prove that it was
+a general consequence of similarity of composition in different
+bodies.&mdash;<i>Graham’s Elements of Chemistry.</i></p>
+
+<h3>IMMENSE CRYSTALS.</h3>
+
+<p>Crystals are found in the most microscopic character, and<span class="pagenum"><a name="Page_25" id="Page_25">25</a></span>
+of an exceedingly large size. A crystal of quartz at Milan is
+three feet and a quarter long, and five feet and a half in circumference:
+its weight is 870 pounds. Beryls have been found
+in New Hampshire measuring four feet in length.&mdash;<i>Dana.</i></p>
+
+<h3>VISIBLE CRYSTALLISATION.</h3>
+
+<p>Professor Tyndall, in a lecture delivered by him at the Royal
+Institution, London, on the properties of Ice, gave the following
+interesting illustration of crystalline force. By perfectly cleaning
+a piece of glass, and placing on it a film of a solution of chloride
+of ammonium or sal ammoniac, the action of crystallisation
+was shown to the whole audience. The glass slide was placed
+in a microscope, and the electric light passing through it was
+concentrated on a white disc. The image of the crystals, as
+they started into existence, and shot across the disc in exquisite
+arborescent and symmetrical forms, excited the admiration
+of every one. The lecturer explained that the heat, causing
+the film of moisture to evaporate, brought the particles of salt
+sufficiently near to exercise the crystalline force, the result
+being the beautiful structure built up with such marvellous
+rapidity.</p>
+
+<h3>UNION OF MINERALOGY AND GEOMETRY.</h3>
+
+<p>It is a peculiar characteristic of minerals, that while plants
+and animals differ in various regions of the earth, mineral matter
+of the same character may be discovered in any part of the world,&mdash;at
+the Equator or towards the Poles; at the summit of the
+loftiest mountains, and in works far beneath the level of the
+sea. The granite of Australia does not necessarily differ from
+that of the British islands; and ores of the same metals (the
+proper geological conditions prevailing) may be found of the
+same general character in all regions. Climate and geographical
+position have no influence on the composition of mineral
+substances.</p>
+
+<p>This uniformity may, in some measure, have induced philosophers
+to seek its extension to the forms of crystallography.
+About 1760 (says Mr. Buckle, in his <i>History of Civilization</i>),
+Romé de Lisle set the first example of studying crystals, according
+to a scheme so large as to include all the varieties of
+their primary forms, and to account for their irregularities and
+the apparent caprice with which they were arranged. In this
+investigation he was guided by the fundamental assumption,
+that what is called an irregularity is in truth perfectly regular,
+and that the operations of nature are invariable. Haüy applied
+this great idea to the almost innumerable forms in which
+minerals crystallise. He thus achieved a complete union between
+mineralogy and geometry; and, bringing the laws of space<span class="pagenum"><a name="Page_26" id="Page_26">26</a></span>
+to bear on the molecular arrangements of matter, he was able
+to penetrate into the intimate structure of crystals. By this
+means he proved that the secondary forms of all crystals are derived
+from their primary forms by a regular process of decrement;
+and that when a substance is passing from a liquid to a solid
+state, its particles cohere, according to a scheme which provides
+for every possible change, since it includes even those subsequent
+layers which alter the ordinary type of the crystal, by
+disturbing its natural symmetry. To ascertain that such violations
+of symmetry are susceptible of mathematical calculation,
+was to make a vast addition to our knowledge; and, by proving
+that even the most uncouth and singular forms are the natural
+results of their antecedents, Haüy laid the foundation of what
+may be called the pathology of the inorganic world. However
+paradoxical such a notion may appear, it is certain that symmetry
+is to crystals what health is to animals; so that an irregularity
+of shape in the first corresponds with an appearance of
+disease in the second.&mdash;See <i>Hist. Civilization</i>, vol. i.</p>
+
+<h3>REPRODUCTIVE CRYSTALLISATION.</h3>
+
+<p>The general belief that only organic beings have the power
+of reproducing lost parts has been disproved by the experiments
+of Jordan on crystals. An octohedral crystal of alum was fractured;
+it was then replaced in a solution, and after a few days
+its injury was seen to be repaired. The whole crystal had of
+course increased in size; but the increase on the broken surface
+had been so much greater that a perfect octohedral form was
+regained.&mdash;<i>G.&nbsp;H. Lewes.</i></p>
+
+<p>This remarkable power possessed by crystals, in common
+with animals, of repairing their own injuries had, however,
+been thus previously referred to by Paget, in his <i>Pathology</i>,
+confirming the experiments of Jordan on this curious subject:
+“The ability to repair the damages sustained by injury ... is
+not an exclusive property of living beings; for even crystals
+will repair themselves when, after pieces have been broken from
+them, they are placed in the same conditions in which they
+were first formed.”</p>
+
+<h3>GLASS BROKEN BY SAND.</h3>
+
+<p>In some glass-houses the workmen show glass which has
+been cooled in the open air; on this they let fall leaden bullets
+without breaking the glass. They afterwards desire you
+to let a few grains of sand fall upon the glass, by which it is
+broken into a thousand pieces. The reason of this is, that the
+lead does not scratch the surface of the glass; whereas the sand,
+being sharp and angular, scratches it sufficiently to produce
+the above effect.</p>
+
+<hr />
+
+<p><span class="pagenum"><a name="Page_27" id="Page_27">27</a></span></p>
+
+<div class="chapter"></div>
+<h2><a name="Sound" id="Sound"></a>Sound and Light.</h2>
+
+<h3>SOUNDING SAND.</h3>
+
+<p>Mr. Hugh Miller, the geologist, when in the island of Eigg,
+in the Hebrides, observed that a musical sound was produced
+when he walked over the white dry sand of the beach. At each
+step the sand was driven from his footprint, and the noise was
+simultaneous with the scattering of the sand; the cause being
+either the accumulated vibrations of the air when struck by
+the driven sand, or the accumulated sounds occasioned by the
+mutual impact of the particles of sand against each other. If
+a musket-ball passing through the air emits a whistling note,
+each individual particle of sand must do the same, however
+faint be the note which it yields; and the accumulation of
+these infinitesimal vibrations must constitute an audible sound,
+varying with the number and velocity of the moving particles.
+In like manner, if two plates of silex or quartz, which are but
+crystals of sand, give out a musical sound when mutually
+struck, the impact or collision of two minute crystals or particles
+of sand must do the same, in however inferior a degree;
+and the union of all these sounds, though singly imperceptible,
+may constitute the musical notes of “the Mountain of the
+Bell” in Arabia Petræa, or the lesser sounds of the trodden
+sea-beach of Eigg.&mdash;<i>North-British Review</i>, No. 5.</p>
+
+<h3>INTENSITY OF SOUND IN RAREFIED AIR.</h3>
+
+<p>The experiences during ascents of the highest mountains
+are contradictory. Saussure describes the sounds on the top
+of Mont Blanc as remarkably weak: a pistol-shot made no
+more noise than an ordinary Chinese cracker, and the popping
+of a bottle of champagne was scarcely audible. Yet Martius,
+in the same situation, was able to distinguish the voices of the
+guides at a distance of 1340 feet, and to hear the tapping of a
+lead pencil upon a metallic surface at a distance of from 75 to
+100 feet.</p>
+
+<p>MM Wertheim and Breguet have propagated sound over
+the wire of an electric telegraph at the rate of 11,454 feet per
+second.</p>
+
+<h3>DISTANCE AT WHICH THE HUMAN VOICE MAY BE HEARD.</h3>
+
+<p>Experience shows that the human voice, under favourable
+circumstances, is capable of filling a larger space than was ever<span class="pagenum"><a name="Page_28" id="Page_28">28</a></span>
+probably enclosed within the walls of a single room. Lieutenant
+Foster, on Parry’s third Arctic expedition, found that he could
+converse with a man across the harbour of Port Bowen, a distance
+of 6696 feet, or about one mile and a quarter. Dr. Young
+records that at Gibraltar the human voice has been heard at a
+distance of ten miles. If sound be prevented from spreading
+and losing itself in the air, either by a pipe or an extensive flat
+surface, as a wall or still water, it may be conveyed to a great
+distance. Biot heard a flute clearly through a tube of cast-iron
+(the water-pipes of Paris) 3120 feet long: the lowest whisper was
+distinctly heard; indeed, the only way not to be heard was not
+to speak at all.</p>
+
+<h3>THE ROAR OF NIAGARA.</h3>
+
+<p>The very nature of the sound of running water pronounces
+its origin to be the bursting of bubbles: the impact of water
+against water is a comparatively subordinate cause, and could
+never of itself occasion the murmur of a brook; whereas, in
+streams which Dr. Tyndall has examined, he, in all cases where
+a ripple was heard, discovered bubbles caused by the broken
+column of water. Now, were Niagara continuous, and without
+lateral vibration, it would be as silent as a cataract of ice. In
+all probability, it has its “contracted sections,” after passing
+which it is broken into detached masses, which, plunging successively
+upon the air-bladders formed by their precursors, suddenly
+liberate their contents, and thus create <i>the thunder of the
+waterfall</i>.</p>
+
+<h3>FIGURES PRODUCED BY SOUND.</h3>
+
+<p>Stretch a sheet of wet paper over the mouth of a glass tumbler
+which has a footstalk, and glue or paste the paper at the
+edges. When the paper is dry, strew dry sand thinly upon its
+surface. Place the tumbler on a table, and hold immediately
+above it, and parallel to the paper, a plate of glass, which
+you also strew with sand, having previously rubbed the edges
+smooth with emery powder. Draw a violin-bow along any
+part of the edges; and as the sand upon the glass is made to
+vibrate, it will form various figures, which will be accurately
+imitated by the sand upon the paper; or if a violin or flute be
+played within a few inches of the paper, they will cause the
+sand upon its surface to form regular lines and figures.</p>
+
+<h3>THE TUNING-FORK A FLUTE-PLAYER.</h3>
+
+<p>Take a common tuning-fork, and on one of its branches
+fasten with sealing-wax a circular piece of card of the size of
+a small wafer, or sufficient nearly to cover the aperture of a
+pipe, as the sliding of the upper end of a flute with the mouth<span class="pagenum"><a name="Page_29" id="Page_29">29</a></span>
+stopped: it may be tuned in unison with the loaded tuning-fork
+by means of the movable stopper or card, or the fork may
+be loaded till the unison is perfect. Then set the fork in vibration
+by a blow on the unloaded branch, and hold the card
+closely over the mouth of the pipe, as in the engraving, when
+a note of surprising clearness and strength will be heard. Indeed
+a flute may be made to “speak” perfectly well, by holding
+close to the opening a vibrating tuning-fork, while the fingering
+proper to the note of the fork is at the same time performed.</p>
+
+<h3>THEORY OF THE JEW’S HARP.</h3>
+
+<p>If you cause the tongue of this little instrument to vibrate,
+it will produce a very low sound; but if you place it before a
+cavity (as the mouth) containing a column of air, which vibrates
+much faster, but in the proportion of any simple multiple,
+it will then produce other higher sounds, dependent upon
+the reciprocation of that portion of the air. Now the bulk of
+air in the mouth can be altered in its form, size, and other circumstances,
+so as to produce by reciprocation many different
+sounds; and these are the sounds belonging to the Jew’s Harp.</p>
+
+<p>A proof of this fact has been given by Mr. Eulenstein, who
+fitted into a long metallic tube a piston, which being moved,
+could be made to lengthen or shorten the efficient column of
+air within at pleasure. A Jew’s Harp was then so fixed that
+it could be made to vibrate before the mouth of the tube, and
+it was found that the column of air produced a series of sounds,
+according as it was lengthened or shortened; a sound being
+produced whenever the length of the column was such that its
+vibrations were a multiple of those of the Jew’s Harp.</p>
+
+<h3>SOLAR AND ARTIFICIAL LIGHT COMPARED.</h3>
+
+<p>The most intensely ignited solid (produced by the flame of
+Lieutenant Drummond’s oxy-hydrogen lamp directed against a
+surface of chalk) appears only as black spots on the disc of the
+sun, when held between it and the eye; or in other words,
+Drummond’s light is to the light of the sun’s disc as 1 to 146.
+Hence we are doubly struck by the felicity with which Galileo,
+as early as 1612, by a series of conclusions on the smallness of
+the distance from the sun at which the disc of Venus was no
+longer visible to the naked eye, arrived at the result that the
+blackest nucleus of the sun’s spots was more luminous than
+the brightest portions of the full moon. (See “The Sun’s
+Light compared with Terrestrial Lights,” in <i>Things not generally
+Known</i>, pp. 4, 5.)</p>
+
+<h3>SOURCE OF LIGHT.</h3>
+
+<p>Mr. Robert Hunt, in a lecture delivered by him at the
+Russell Institution, “On the Physics of a Sunbeam,” mentions<span class="pagenum"><a name="Page_30" id="Page_30">30</a></span>
+some experiments by Lord Brougham on the sunbeam, in which,
+by placing the edge of a sharp knife just within the limit of
+the light, the ray was inflected from its previous direction, and
+coloured red; and when another knife was placed on the opposite
+side, it was deflected, and the colour was blue. These
+experiments (says Mr. Hunt) seem to confirm Sir Isaac Newton’s
+theory, that light is a fluid emitted from the sun.</p>
+
+<h3>THE UNDULATORY SCALE OF LIGHT.</h3>
+
+<p>The white light of the sun is well known to be composed of
+several coloured rays; or rather, according to the theory of
+undulations, when the rate at which a ray vibrates is altered,
+a different sensation is produced upon the optic nerve. The
+analytical examination of this question shows that to produce
+a red colour the ray of light must give 37,640 undulations in
+an inch, and 458,000,000,000,000 in a second. Yellow light requires
+44,000 undulations in an inch, and 535,000,000,000,000
+in a second; whilst the effect of blue results from 51,110 undulations
+within an inch, and 622,000,000,000,000 of waves in
+a second of time.&mdash;<i>Hunt’s Poetry of Science.</i></p>
+
+<h3>VISIBILITY OF OBJECTS.</h3>
+
+<p>In terrestrial objects, the form, no less than the modes of
+illumination, determines the magnitude of the smallest angle
+of vision for the naked eye. Adams very correctly observed
+that a long and slender staff can be seen at a much greater
+distance than a square whose sides are equal to the diameter of
+the staff. A stripe may be distinguished at a greater distance
+than a spot, even when both are of the same diameter.</p>
+
+<p>The <i>minimum</i> optical visual angle at which terrestrial objects
+can be recognised by the naked eye has been gradually
+estimated lower and lower, from the time when Robert Hooke
+fixed it exactly at a full minute, and Tobias Meyer required
+34″ to perceive a black speck on white paper, to the period
+of Leuwenhoeck’s experiments with spiders’ threads, which are
+visible to ordinary sight at an angle of 4″·7. In Hueck’s most
+accurate experiments on the problem of the movement of the
+crystalline lens, white lines on a black ground were seen at an
+angle of 1″·2; a spider’s thread at 0″·6; and a fine glistening
+wire at scarcely 0″·2.</p>
+
+<blockquote>
+
+<p>Humboldt, when at Chillo, near Quito, where the crests of the
+volcano of Pichincha lay at a horizontal distance of 90,000 feet, was
+much struck by the circumstance that the Indians standing near distinguished
+the figure of Bonpland (then on an expedition to the volcano),
+as a white point moving on the black basaltic sides of the rock, sooner
+than Humboldt could discover him with a telescope. Bonpland was
+enveloped in a white cotton poncho: assuming the breadth across the
+shoulders to vary from three to five feet, according as the mantle clung<span class="pagenum"><a name="Page_31" id="Page_31">31</a></span>
+to the figure or fluttered in the breeze, and judging from the known
+distance, the angle at which the moving object could be distinctly seen
+varied from 7″ to 12″. White objects on a black ground are, according
+to Hueck, distinguished at a greater distance than black objects on a
+white ground.</p>
+
+<p>Gauss’s heliotrope light has been seen with the naked eye reflected
+from the Brocken on Hobenhagen at a distance of about 227,000 feet,
+or more than 42 miles; being frequently visible at points in which the
+apparent breadth of a three-inch mirror was only 0″·43.</p></blockquote>
+
+<h3>THE SMALLEST BRIGHT BODIES.</h3>
+
+<p>Ehrenberg has found from experiments on the dust of diamonds,
+that a diamond superficies of 1/100th of a line in diameter
+presents a much more vivid light to the naked eye than one of
+quicksilver of the same diameter. On pressing small globules
+of quicksilver on a glass micrometer, he easily obtained smaller
+globules of the 1/100th to the 1/2000th of a line in diameter. In
+the sunshine he could only discern the reflection of light, and
+the existence of such globules as were 1/300th of a line in diameter,
+with the naked eye. Smaller ones did not affect his
+eye; but he remarked that the actual bright part of the globule
+did not amount to more than 1/900th of a line in diameter.
+Spider threads of 1/2000th in diameter were still discernible
+from their lustre. Ehrenberg concludes that there are in organic
+bodies magnitudes capable of direct proof which are in
+diameter 1/100000 of a line; and others, that can be indirectly
+proved, which may be less than a six-millionth part of a Parisian
+line in diameter.</p>
+
+<h3>VELOCITY OF LIGHT.</h3>
+
+<p>It is scarcely possible so to strain the imagination as to conceive
+the Velocity with which Light travels. “What mere
+assertion will make any man believe,” asks Sir John Herschel,
+“that in one second of time, in one beat of the pendulum of
+a clock, a ray of light travels over 192,000 miles; and would
+therefore perform the tour of the world in about the same time
+that it requires to wink with our eyelids, and in much less time
+than a swift runner occupies in taking a single stride?” Were
+a cannon-ball shot directly towards the sun, and were it to maintain
+its full speed, it would be twenty years in reaching it; and
+yet light travels through this space in seven or eight minutes.</p>
+
+<p>The result given in the <i>Annuaire</i> for 1842 for the velocity
+of light in a second is 77,000 leagues, which corresponds to
+215,834 miles; while that obtained at the Pulkowa Observatory
+is 189,746 miles. William Richardson gives as the result of the
+passage of light from the sun to the earth 8´ 19″·28, from which
+we obtain a velocity of 215,392 miles in a second.&mdash;<i>Memoirs of
+the Astronomical Society</i>, vol. iv.</p>
+
+<p><span class="pagenum"><a name="Page_32" id="Page_32">32</a></span>
+In other words, light travels a distance equal to eight times
+the circumference of the earth between two beats of a clock.
+This is a prodigious velocity; but the measure of it is very certain.&mdash;<i>Professor
+Airy.</i></p>
+
+<p>The navigator who has measured the earth’s circuit by his
+hourly progress, or the astronomer who has paced a degree of
+the meridian, can alone form a clear idea of velocity, when we
+tell him that light moves through a space equal to the circumference
+of the earth in <i>the eighth part of a second</i>&mdash;in the twinkling
+of an eye.</p>
+
+<blockquote>
+
+<p>Could an observer, placed in the centre of the earth, see this moving
+light, as it describes the earth’s circumference, it would appear a luminous
+ring; that is, the impression of the light at the commencement of
+its journey would continue on the retina till the light had completed its
+circuit. Nay, since the impression of light continues longer than the
+<i>fourth</i> part of a second, <i>two</i> luminous rings would be seen, provided the
+light made <i>two</i> rounds of the earth, and in paths not coincident.</p></blockquote>
+
+<h3>APPARATUS FOR THE MEASUREMENT OF LIGHT.</h3>
+
+<p>Humboldt enumerates the following different methods
+adopted for the Measurement of Light: a comparison of the
+shadows of artificial lights, differing in numbers and distance;
+diaphragms; plane-glasses of different thickness and colour;
+artificial stars formed by reflection on glass spheres; the juxtaposition
+of two seven-feet telescopes, separated by a distance
+which the observer could pass in about a second; reflecting instruments
+in which two stars can be simultaneously seen and
+compared, when the telescope has been so adjusted that the
+star gives two images of like intensity; an apparatus having
+(in front of the object-glass) a mirror and diaphragms, whose
+rotation is measured on a ring; telescopes with divided object-glasses,
+on either half of which the stellar light is received
+through a prism; astrometers, in which a prism reflects the
+image of the moon or Jupiter, and concentrates it through a
+lens at different distances into a star more or less bright.&mdash;<i>Cosmos</i>,
+vol. iii.</p>
+
+<h3>HOW FIZEAU MEASURED THE VELOCITY OF LIGHT.</h3>
+
+<p>This distinguished physicist has submitted the Velocity of
+Light to terrestrial measurement by means of an ingeniously
+constructed apparatus, in which artificial light (resembling
+stellar light), generated from oxygen and hydrogen, is made
+to pass back, by means of a mirror, over a distance of 28,321
+feet to the same point from which it emanated. A disc, having
+720 teeth, which made 12·6 rotations in a second, alternately
+obscured the ray of light and allowed it to be seen
+between the teeth on the margin. It was supposed, from the
+marking of a counter, that the artificial light traversed 56,642<span class="pagenum"><a name="Page_33" id="Page_33">33</a></span>
+feet, or the distance to and from the stations, in 1/1800th part of
+a second, whence we obtain a velocity of 191,460 miles in a second.<a name="FNanchor_12" id="FNanchor_12" href="#Footnote_12" class="fnanchor">12</a>
+This result approximates most closely to Delambre’s
+(which was 189,173 miles), as obtained from Jupiter’s satellites.</p>
+
+<blockquote>
+
+<p>The invention of the rotating mirror is due to Wheatstone, who made
+an experiment with it to determine the velocity of the propagation of the
+discharge of a Leyden battery. The most striking application of the
+idea was made by Fizeau and Foucault, in 1853, in carrying out a proposition
+made by Arago, soon after the invention of the mirror: we have
+here determined in a distance of twelve feet no less than the velocity
+with which light is propagated, which is known to be nearly 200,000
+miles a second; the distance mentioned corresponds therefore to the
+77-millionth part of a second. The object of these measurements was
+to compare the velocity of light in air with its velocity in water; which,
+when the length is greater, is not sufficiently transparent. The most
+complete optical and mechanical aids are here necessary: the mirror of
+Foucault made from 600 to 800 revolutions in a second, while that of
+Fizeau performed 1200 to 1500 in the same time.&mdash;<i>Prof. Helmholtz on
+the Methods of Measuring very small Portions of Time.</i></p></blockquote>
+
+<h3>WHAT IS DONE BY POLARISATION OF LIGHT.</h3>
+
+<p>Malus, in 1808, was led by a casual observation of the light
+of the setting sun, reflected from the windows of the Palais de
+Luxembourg, at Paris, to investigate more thoroughly the phenomena
+of double refraction, of ordinary and of chromatic polarisation,
+of interference and of diffraction of light. Among
+his results may be reckoned the means of distinguishing between
+direct and reflected light; the power of penetrating, as it were,
+into the constitution of the body of the sun and of its luminous
+envelopes; of measuring the pressure of atmospheric strata,
+and even the smallest amount of water they contain; of ascertaining
+the depths of the ocean and its rocks by means of a
+tourmaline plate; and in accordance with Newton’s prediction,
+of comparing the chemical composition of several substances
+with their optical effects.</p>
+
+<blockquote>
+
+<p>Arago, in a letter to Humboldt, states that by the aid of his polariscope,
+he discovered, before 1820, that the light of all terrestrial objects
+in a state of incandescence, whether they be solid or liquid, is natural,
+so long as it emanates from the object in perpendicular rays. On the
+other hand, if such light emanate at an acute angle, it presents manifest
+proofs of polarisation. This led M. Arago to the remarkable conclusion,
+that light is not generated on the surface of bodies only, but that
+some portion is actually engendered within the substance itself, even in
+the case of platinum.</p></blockquote>
+
+<p>A ray of light which reaches our eyes after traversing many
+millions of miles, from, the remotest regions of heaven, announces,
+as it were of itself, in the polariscope, whether it is<span class="pagenum"><a name="Page_34" id="Page_34">34</a></span>
+reflected or refracted, whether it emanates from a solid or fluid
+or gaseous body; it announces even the degree of its intensity.&mdash;<i>Humboldt’s
+Cosmos</i>, vols. i. and ii.</p>
+
+<h3>MINUTENESS OF LIGHT.</h3>
+
+<p>There is something wonderful, says Arago, in the experiments
+which have led natural philosophers legitimately to talk
+of the different sides of a ray of light; and to show that millions
+and millions of these rays can simultaneously pass through
+the eye of a needle without interfering with each other!</p>
+
+<h3>THE IMPORTANCE OF LIGHT.</h3>
+
+<p>Light affects the respiration of animals just as it affects the
+respiration of plants. This is novel doctrine, but it is demonstrable.
+In the day-time we expire more carbonic acid than
+during the night; a fact known to physiologists, who explain
+it as the effect of sleep: but the difference is mainly owing to
+the presence or absence of sunlight; for sleep, as sleep, <i>increases</i>,
+instead of diminishing, the amount of carbonic acid expired,
+and a man sleeping will expire more carbonic acid than if he
+lies quietly awake under the same conditions of light and temperature;
+so that if less is expired during the night than during
+the day, the reason cannot be sleep, but the absence of light.
+Now we understand why men are sickly and stunted who live
+in narrow streets, alleys, and cellars, compared with those who,
+under similar conditions of poverty and dirt, live in the sunlight.&mdash;<i>Blackwood’s
+Edinburgh Magazine</i>, 1858.</p>
+
+<blockquote>
+
+<p>The influence of light on the colours of organised creation is well
+shown in the sea. Near the shores we find seaweeds of the most beautiful
+hues, particularly on the rocks which are left dry by the tides; and
+the rich tints of the actiniæ which inhabit shallow water must often
+have been observed. The fishes which swim near the surface are also
+distinguished by the variety of their colours, whereas those which live at
+greater depths are gray, brown, or black. It has been found that after
+a certain depth, where the quantity of light is so reduced that a mere
+twilight prevails, the inhabitants of the ocean become nearly colourless.&mdash;<i>Hunt’s
+Poetry of Science.</i></p></blockquote>
+
+<h3>ACTION OF LIGHT ON MUSCULAR FIBRES.</h3>
+
+<p>That light is capable of acting on muscular fibres, independently
+of the influence of the nerves, was mentioned by several
+of the old anatomists, but repudiated by later authorities. M.
+Brown Séquard has, however, proved to the Royal Society that
+some portions of muscular fibre&mdash;the iris of the eye, for example&mdash;are
+affected by light independently of any reflex action of the
+nerves, thereby confirming former experiences. The effect is
+produced by the illuminating rays only, the chemical and heat
+rays remaining neutral. And not least remarkable is the fact,<span class="pagenum"><a name="Page_35" id="Page_35">35</a></span>
+that the iris of an eel showed itself susceptible of the excitement
+<i>sixteen days after the eyes were removed from the creature’s
+head</i>. So far as is yet known, this muscle is the only one on
+which light thus takes effect.&mdash;<i>Phil. Trans. 1857.</i></p>
+
+<h3>LIGHT NIGHTS.</h3>
+
+<p>It is not possible, as well-attested facts prove, perfectly to
+explain the operations at work in the much-contested upper
+boundaries of our atmosphere. The extraordinary lightness of
+whole nights in the year 1831, during which small print might
+be read at midnight in the latitudes of Italy and the north of
+Germany, is a fact directly at variance with all that we know,
+according to the most recent and acute researches on the crepuscular
+theory and the height of the atmosphere.&mdash;<i>Biot.</i></p>
+
+<h3>PHOSPHORESCENCE OF PLANTS.</h3>
+
+<p>Mr. Hunt recounts these striking instances. The leaves of
+the <i>œnothera macrocarpa</i> are said to exhibit phosphoric light
+when the air is highly charged with electricity. The agarics
+of the olive-grounds of Montpelier too have been observed to be
+luminous at night; but they are said to exhibit no light, even
+in darkness, <i>during the day</i>. The subterranean passages of the
+coal-mines near Dresden are illuminated by the phosphorescent
+light of the <i>rhizomorpha phosphoreus</i>, a peculiar fungus.
+On the leaves of the Pindoba palm grows a species of agaric
+which is exceedingly luminous at night; and many varieties
+of the lichens, creeping along the roofs of caverns, lend to them
+an air of enchantment by the soft and clear light which they
+diffuse. In a small cave near Penryn, a luminous moss is
+abundant; it is also found in the mines of Hesse. According
+to Heinzmann, the <i>rhizomorpha subterranea</i> and <i>aidulæ</i> are also
+phosphorescent.&mdash;See <i>Poetry of Science</i>.</p>
+
+<h3>PHOSPHORESCENCE OF THE SEA.</h3>
+
+<p>By microscopic examination of the myriads of minute insects
+which cause this phenomenon, no other fact has been elicited
+than that they contain a fluid which, when squeezed out, leaves
+a train of light upon the surface of the water. The creatures
+appear almost invariably on the eve of some change of weather,
+which would lead us to suppose that their luminous phenomena
+must be connected with electrical excitation; and of this Mr. C.
+Peach of Fowey has furnished the most satisfactory proofs yet
+obtained.<a name="FNanchor_13" id="FNanchor_13" href="#Footnote_13" class="fnanchor">13</a></p>
+
+<h3>LIGHT FROM THE JUICE OF A PLANT.</h3>
+
+<p>In Brazil has been observed a plant, conjectured to be an<span class="pagenum"><a name="Page_36" id="Page_36">36</a></span>
+Euphorbium, very remarkable for the light which it yields when
+cut. It contains a milky juice, which exudes as soon as the
+plant is wounded, and appears luminous for several seconds.</p>
+
+<h3>LIGHT FROM FUNGUS.</h3>
+
+<p>Phosphorescent funguses have been found in Brazil by Mr.
+Gardner, growing on the decaying leaves of a dwarf palm. They
+vary from one to two inches across, and the whole plant gives
+out at night a bright phosphorescent light, of a pale greenish
+hue, similar to that emitted by fire-flies and phosphorescent
+marine animals. The light given out by a few of these fungi
+in a dark room is sufficient to read by. A very large phosphorescent
+species is occasionally found in the Swan River colony.</p>
+
+<h3>LIGHT FROM BUTTONS.</h3>
+
+<p>Upon highly polished gilt buttons no figure whatever can
+be seen by the most careful examination; yet, when they are
+made to reflect the light of the sun or of a candle upon a piece
+of paper held close to them, they give a beautiful geometrical
+figure, with ten rays issuing from the centre, and terminating
+in a luminous rim.</p>
+
+<h3>COLOURS OF SCRATCHES.</h3>
+
+<p>An extremely fine scratch on a well-polished surface may
+be regarded as having a concave, cylindrical, or at least a
+curved surface, capable of reflecting light in all directions; this
+is evident, for it is visible in all directions. Hence a single
+scratch or furrow in a surface may produce colours by the interference
+of the rays reflected from its opposite edges. Examine
+a spider’s thread in the sunshine, and it will gleam with vivid
+colours. These may arise from a similar cause; or from the
+thread itself, as spun by the animal, consisting of several
+threads agglutinated together, and thus presenting, not a cylindrical,
+but a furrowed surface.</p>
+
+<h3>MAGIC BUST.</h3>
+
+<p>Sir David Brewster has shown how the rigid features of a
+white bust may be made to move and vary their expression,
+sometimes smiling and sometimes frowning, by moving rapidly
+in front of the bust a bright light, so as to make the lights and
+shadows take every possible direction and various degrees of
+intensity; and if the bust be placed before a concave mirror,
+its image may be made to do still more when it is cast upon
+wreaths of smoke.</p>
+
+<h3>COLOURS HIT MOST FREQUENTLY DURING BATTLE.</h3>
+
+<p>It would appear from numerous observations that soldiers<span class="pagenum"><a name="Page_37" id="Page_37">37</a></span>
+are hit during battle according to the colour of their dress in
+the following order: red is the most fatal colour; the least
+fatal, Austrian gray. The proportions are, red, 12; rifle-green,
+7; brown, 6; Austrian bluish-gray, 5.&mdash;<i>Jameson’s Journal</i>, 1853.</p>
+
+<h3>TRANSMUTATION OF TOPAZ.</h3>
+
+<p>Yellow topazes may be converted into pink by heat; but it
+is a mistake to suppose that in the process the yellow colour is
+changed into pink: the fact is, that one of the pencils being
+yellow and the other pink, the yellow is discharged by heat,
+thus leaving the pink unimpaired.</p>
+
+<h3>COLOURS AND TINTS.</h3>
+
+<p>M. Chevreul, the <i>Directeur des Gobelins</i>, has presented to the
+French Academy a plan for a universal chromatic scale, and a
+methodical classification of all imaginable colours. Mayer, a
+professor at Göttingen, calculated that the different combinations
+of primitive colours produced 819 different tints; but M.
+Chevreul established not less than 14,424, all very distinct and
+easily recognised,&mdash;all of course proceeding from the three primitive
+simple colours of the solar spectrum, red, yellow, and
+blue. For example, he states that in the violet there are twenty-eight
+colours, and in the dahlia forty-two.</p>
+
+<h3>OBJECTS REALLY OF NO COLOUR.</h3>
+
+<p>A body appears to be of the colour which it reflects; as we
+see it only by reflected rays, it can but appear of the colour
+of those rays. Thus grass is green because it absorbs all except
+the green rays. Flowers, in the same manner, reflect the various
+colours of which they appear to us: the rose, the red rays;
+the violet, the blue; the daffodil, the yellow, &amp;c. But these
+are not the permanent colours of the grass and flowers; for
+wherever you see these colours, the objects must be illuminated;
+and light, from whatever source it proceeds, is of the same nature,
+composed of the various coloured rays which paint the
+grass, the flowers, and every coloured object in nature. Objects
+in the dark have no colour, or are black, which is the same
+thing. You can never see objects without light. Light is composed
+of colours, therefore there can be no light without colours;
+and though every object is black or without colour in
+the dark, it becomes coloured as soon as it becomes visible.</p>
+
+<h3>THE DIORAMA&mdash;WHY SO PERFECT AN ILLUSION.</h3>
+
+<p>Because when an object is viewed at so great a distance
+that the optic axes of both eyes are sensibly parallel when
+directed towards it, the perspective projections of it, seen by<span class="pagenum"><a name="Page_38" id="Page_38">38</a></span>
+each eye separately, are similar; and the appearance to the
+two eyes is precisely the same as when the object is seen by
+one eye only. There is, in such case, no difference between
+the visual appearance of an object in relief and its perspective
+projection on a plane surface; hence pictorial representations
+of distant objects, when those circumstances which would prevent
+or disturb the illusion are carefully excluded, may be
+rendered such perfect resemblances of the objects they are intended
+to represent as to be mistaken for them. The Diorama
+is an instance of this.&mdash;<i>Professor Wheatstone</i>; <i>Philosophical
+Transactions</i>, 1838.</p>
+
+<h3>CURIOUS OPTICAL EFFECTS AT THE CAPE.</h3>
+
+<p>Sir John Herschel, in his observatory at Feldhausen, at the
+base of the Table Mountain, witnessed several curious optical
+effects, arising from peculiar conditions of the atmosphere incident
+to the climate of the Cape. In the hot season “the
+nights are for the most part superb;” but occasionally, during
+the excessive heat and dryness of the sandy plains, “the optical
+tranquillity of the air” is greatly disturbed. In some
+cases, the images of the stars are violently dilated into nebular
+balls or puffs of 15′ in diameter; on other occasions they form
+“soft, round, quiet pellets of 3′ or 4′ diameter,” resembling
+planetary nebulæ. In the cooler months the tranquillity of
+the image and the sharpness of vision are such, that hardly any
+limit is set to magnifying power but that which arises from
+the aberration of the specula. On occasions like these, optical
+phenomena of extraordinary splendour are produced by viewing
+a bright star through a diaphragm of cardboard or zinc pierced
+in regular patterns of circular holes by machinery: these phenomena
+surprise and delight every person that sees them.
+When close double stars are viewed with the telescope, with a
+diaphragm in the form of an equilateral triangle, the discs of
+the two stars, which are exact circles, have a clearness and
+perfection almost incredible.</p>
+
+<h3>THE TELESCOPE AND THE MICROSCOPE.</h3>
+
+<p>So singular is the position of the Telescope and the Microscope
+among the great inventions of the age, that no other
+process but that which they embody could make the slightest
+approximation to the secrets which they disclose. The steam-engine
+might have been imperfectly replaced by an air or an
+ether-engine; and a highly elastic fluid might have been, and
+may yet be, found, which shall impel the “rapid car,” or drag
+the merchant-ship over the globe. The electric telegraph,
+now so perfect and unerring, might have spoken to us in the<span class="pagenum"><a name="Page_39" id="Page_39">39</a></span>
+rude “language of chimes;” or sound, in place of electricity,
+might have passed along the metallic path, and appealed to
+the ear in place of the eye. For the printing-press and the
+typographic art might have been found a substitute, however
+poor, in the lithographic process; and knowledge might have
+been widely diffused by the photographic printing powers of
+the sun, or even artificial light. But without the telescope and
+the microscope, the human eye would have struggled in vain to
+study the worlds beyond our own, and the elaborate structures
+of the organic and inorganic creation could never have been
+revealed.&mdash;<i>North-British Review</i>, No. 50.</p>
+
+<h3>INVENTION OF THE MICROSCOPE.</h3>
+
+<p>The earliest magnifying lens of which we have any knowledge
+was one rudely made of rock-crystal, which Mr. Layard
+found, among a number of glass bowls, in the north-west palace
+of Nimroud; but no similar lens has been found or described
+to induce us to believe that the microscope, either single or
+compound, was invented and used as an instrument previous
+to the commencement of the seventeenth century. In the
+beginning of the first century, however, Seneca alludes to the
+magnifying power of a glass globe filled with water; but as he
+only states that it made small and indistinct letters appear
+larger and more distinct, we cannot consider such a casual remark
+as the invention of the single microscope, though it might
+have led the observer to try the effect of smaller globes, and
+thus obtain magnifying powers sufficient to discover phenomena
+otherwise invisible.</p>
+
+<p>Lenses of glass were undoubtedly in existence at the time
+of Pliny; but at that period, and for many centuries afterwards,
+they appear to have been used only as burning or as
+reading glasses; and no attempt seems to have been made to
+form them of so small a size as to entitle them to be regarded
+even as the precursors of the single microscope.&mdash;<i>North-British
+Review</i>, No. 50.</p>
+
+<blockquote>
+
+<p>The <i>rock-crystal lens</i> found at Nineveh was examined by Sir David
+Brewster. It was not entirely circular in its aperture. Its general form
+was that of a plano-convex lens, the plane side having been formed of one
+of the original faces of the six-sided crystal quartz, as Sir David ascertained
+by its action on polarised light: this was badly polished and
+scratched. The convex face of the lens had not been ground in a dish-shaped
+tool, in the manner in which lenses are now formed, but was
+shaped on a lapidary’s wheel, or in some such manner. Hence it was
+unequally thick; but its extreme thickness was 2/10ths of an inch, its
+focal length being 4½ inches. It had twelve remains of cavities, which
+had originally contained liquids or condensed gases. Sir David has
+assigned reasons why this could not be looked upon as an ornament, but
+a true optical lens. In the same ruins were found some decomposed
+glass.</p></blockquote>
+
+<p><span class="pagenum"><a name="Page_40" id="Page_40">40</a></span></p>
+
+<h3>HOW TO MAKE THE FISH-EYE MICROSCOPE.</h3>
+
+<p>Very good microscopes may be made with the crystalline
+lenses of fish, birds, and quadrupeds. As the lens of fishes is
+spherical or spheroidal, it is absolutely necessary, previous to
+its use, to determine its optical axis and the axis of vision
+of the eye from which it is taken, and place the lens in such a
+manner that its axis is a continuation of the axis of our own
+eye. In no other direction but this is the albumen of which
+the lens consists symmetrically disposed in laminæ of equal
+density round a given line, which is the axis of the lens; and
+in no other direction does the gradation of density, by which
+the spherical aberration is corrected, preserve a proper relation
+to the axis of vision.</p>
+
+<blockquote>
+
+<p>When the lens of any small fish, such as a minnow, a par, or trout,
+has been taken out, along with the adhering vitreous humour, from the
+eye-ball by cutting the sclerotic coat with a pair of scissors, it should be
+placed upon a piece of fine silver-paper previously freed from its minute
+adhering fibres. The absorbent nature of the paper will assist in removing
+all the vitreous humour from the lens; and when this is carefully
+done, by rolling it about with another piece of silver-paper, there
+will still remain, round or near the equator of the lens, a black ridge,
+consisting of the processes by which it was suspended in the eye-ball.
+The black circle points out to us the true axis of the lens, which is perpendicular
+to a plane passing through it. When the small crystalline
+has been freed from all the adhering vitreous humour, the capsule which
+contains it will have a surface as fine as a pellicle of fluid. It is then to
+be dropped from the paper into a cavity formed by a brass rim, and its
+position changed till the black circle is parallel to the circular rim, in
+which case only the axis of the lens will be a continuation of the axis of
+the observer’s eye.&mdash;<i>Edin. Jour. Science</i>, vol. ii.</p></blockquote>
+
+<h3>LEUWENHOECK’S MICROSCOPES.</h3>
+
+<p>Leuwenhoeck, the father of microscopical discovery, communicated
+to the Royal Society, in 1673, a description of the
+structure of a bee and a louse, seen by aid of his improved microscopes;
+and from this period until his decease in 1723, he
+regularly transmitted to the society his microscopical observations
+and discoveries, so that 375 of his papers and letters are
+preserved in the society’s archives, extending over fifty years.
+He further bequeathed to the Royal Society a cabinet of twenty-six
+microscopes, which he had ground himself and set in silver,
+mostly extracted by him from minerals; these microscopes were
+exhibited to Peter the Great when he was at Delft in 1698. In
+acknowledging the bequest, the council of the Royal Society,
+in 1724, presented Leuwenhoeck’s daughter with a handsome
+silver bowl, bearing the arms of the society.&mdash;<i>Weld’s History
+of the Royal Society</i>, vol. i.</p>
+
+<h3>DIAMOND LENSES FOR MICROSCOPES.</h3>
+
+<p>In recommending the employment of Diamond and other<span class="pagenum"><a name="Page_41" id="Page_41">41</a></span>
+gems in the construction of Microscopes, Sir David Brewster
+has been met with the objection that they are too expensive for
+such a purpose; and, says Sir David, “they certainly are for
+instruments intended merely to instruct and amuse. But if
+we desire to make great discoveries, to unfold secrets yet hid
+in the cells of plants and animals, we must not grudge even a
+diamond to reveal them. If Mr. Cooper and Sir James South
+have given a couple of thousand pounds a piece for a refracting
+telescope, in order to study what have been miscalled ‘dots’
+and ‘lumps’ of light on the sky; and if Lord Rosse has expended
+far greater sums on a reflecting telescope for analysing
+what has been called ‘sparks of mud and vapour’ encumbering
+the azure purity of the heavens,&mdash;why should not other philosophers
+open their purse, if they have one, and other noblemen
+sacrifice some of their household jewels, to resolve the microscopic
+structures of our own real world, and disclose secrets
+which the Almighty must have intended that we should know?”&mdash;<i>Proceedings
+of the British Association</i>, 1857.</p>
+
+<h3>THE EYE AND THE BRAIN SEEN THROUGH A MICROSCOPE.</h3>
+
+<p>By a microscopic examination of the retina and optic nerve
+and the brain, M. Bauer found them to consist of globules of
+1/2800th to 1/4000th an inch diameter, united by a transparent
+viscid and coagulable gelatinous fluid.</p>
+
+<h3>MICROSCOPICAL EXAMINATION OF THE HAIR.</h3>
+
+<p>If a hair be drawn between the finger and thumb, from the
+end to the root, it will be distinctly felt to give a greater resistance
+and a different sensation to that which is experienced
+when drawn the opposite way: in consequence, if the hair be
+rubbed between the fingers, it will only move one way (travelling
+in the direction of a line drawn from its termination to its
+origin from the head or body), so that each extremity may thus
+be easily distinguished, even in the dark, by the touch alone.</p>
+
+<p>The mystery is resolved by the achromatic microscope. A
+hair viewed on a dark ground as an <i>opaque</i> object with a high
+power, not less than that of a lens of one-thirtieth of an inch
+focus, and dully illuminated by a <i>cup</i>, the hair is seen to be indented
+with teeth somewhat resembling those of a coarse round
+rasp, but extremely irregular and rugged: as these incline all
+in one direction, like those of a common file, viz. from the
+origin of the hair towards its extremity, it sufficiently explains
+the above singular property.</p>
+
+<p>This is a singular proof of the acuteness of the sense of feeling,
+for the said teeth may be felt much more easily than they
+can be seen. We may thus understand why a razor will cut a
+hair in two much more easily when drawn against its teeth than
+in the opposite direction.&mdash;<i>Dr. Goring.</i></p>
+
+<p><span class="pagenum"><a name="Page_42" id="Page_42">42</a></span></p>
+
+<h3>THE MICROSCOPE AND THE SEA.</h3>
+
+<p>What myriads has the microscope revealed to us of the rich
+luxuriance of animal life in the ocean, and conveyed to our astonished
+senses a consciousness of the universality of life! In
+the oceanic depths every stratum of water is animated, and
+swarms with countless hosts of small luminiferous animalcules,
+mammaria, crustacea, peridinea, and circling nereides, which,
+when attracted to the surface by peculiar meteorological conditions,
+convert every wave into a foaming band of flashing light.</p>
+
+<h3>USE OF THE MICROSCOPE TO MINERALOGISTS.</h3>
+
+<p>M. Dufour has shown that an imponderable quantity of a
+substance can be crystallised; and that the crystals so obtained
+are quite characteristic of the substances, as of sugar, chloride
+of sodium, arsenic, and mercury. This process may be extremely
+valuable to the mineralogist and toxicologist when the
+substance for examination is too small to be submitted to tests.
+By aid of the microscope, also, shells are measured to the thousandth
+part of an inch.</p>
+
+<h3>FINE DOWN OF QUARTZ.</h3>
+
+<p>Sir David Brewster having broken in two a crystal of quartz
+of a smoky colour, found both surfaces of the fracture absolutely
+black; and the blackness appeared at first sight to be
+owing to a thin film of opaque matter which had insinuated
+itself into the crevice. This opinion, however, was untenable,
+as every part of the surface was black, and the two halves of the
+crystals could not have stuck together had the crevice extended
+across the whole section. Upon further examination Sir David
+found that the surface was perfectly transparent by transmitted
+light, and that the blackness of the surfaces arose from their
+being entirely composed of <i>a fine down of quartz</i>, or of short
+and slender filaments, whose diameter was so exceedingly small
+that they were incapable of reflecting a single ray of the strongest
+light; and they could not exceed the <i>one third of the millionth
+part of an inch</i>. This curious specimen is in the cabinet
+of her grace the Duchess of Gordon.</p>
+
+<h3>MICROSCOPIC WRITING.</h3>
+
+<p>Professor Kelland has shown, in Paris, on a spot no larger
+than the head of a small pin, by means of powerful microscopes,
+several specimens of distinct and beautiful writing, one of them
+containing the whole of the Lord’s Prayer written within this
+minute compass. In reference to this, two remarkable facts in
+Layard’s latest work on Nineveh show that the national records
+of Assyria were written on square bricks, in characters so small
+as scarcely to be legible without a microscope; in fact, a microscope,
+as we have just shown, was found in the ruins of Nimroud.</p>
+
+<p><span class="pagenum"><a name="Page_43" id="Page_43">43</a></span></p>
+
+<h3>HOW TO MAKE A MAGIC MIRROR.</h3>
+
+<p>Draw a figure with weak gum-water upon the surface of a
+convex mirror. The thin film of gum thus deposited on the
+outline or details of the figure will not be visible in dispersed
+daylight; but when made to reflect the rays of the sun, or those
+of a divergent pencil, will be beautifully displayed by the lines
+and tints occasioned by the diffraction of light, or the interference
+of the rays passing through the film with those which
+pass by it.</p>
+
+<h3>SIR DAVID BREWSTER’S KALEIDOSCOPE.</h3>
+
+<p>The idea of this instrument, constructed for the purpose of
+creating and exhibiting a variety of beautiful and perfectly
+symmetrical forms, first occurred to Sir David Brewster in 1814,
+when he was engaged in experiments on the polarisation of
+light by successive reflections between plates of glass. The
+reflectors were in some instances inclined to each other; and
+he had occasion to remark the circular arrangement of the
+images of a candle round a centre, or the multiplication of the
+sectors formed by the extremities of the glass plates. In repeating
+at a subsequent period the experiments of M. Biot on the
+action of fluids upon light, Sir David Brewster placed the fluids
+in a trough, formed by two plates of glass cemented together at
+an angle; and the eye being necessarily placed at one end, some
+of the cement, which had been pressed through between the
+plates, appeared to be arranged into a regular figure. The remarkable
+symmetry which it presented led to Dr. Brewster’s
+investigation of the cause of this phenomenon; and in so doing
+he discovered the leading principles of the Kaleidoscope.</p>
+
+<p>By the advice of his friends, Dr. Brewster took out a patent
+for his invention; in the specification of which he describes the
+kaleidoscope in two different forms. The instrument, however,
+having been shown to several opticians in London, became
+known before he could avail himself of his patent; and being
+simple in principle, it was at once largely manufactured. It is
+calculated that not less than 200,000 kaleidoscopes were sold
+in three months in London and Paris; though out of this number,
+Dr. Brewster says, not perhaps 1000 were constructed upon
+scientific principles, or were capable of giving any thing like a
+correct idea of the power of his kaleidoscope.</p>
+
+<h3>THE KALEIDOSCOPE THOUGHT TO BE ANTICIPATED.</h3>
+
+<p>In the seventh edition of a work on gardening and planting,
+published in 1739, by Richard Bradley, F.R.S., late Professor
+of Botany in the University of Cambridge, we find the
+following details of an invention, “by which the best designers<span class="pagenum"><a name="Page_44" id="Page_44">44</a></span>
+and draughtsmen may improve and help their fancies.
+They must choose two pieces of looking-glass of equal bigness,
+of the figure of a long square. These must be covered on the
+back with paper or silk, to prevent rubbing off the silver. This
+covering must be so put on that nothing of it appears about the
+edges of the bright side. The glasses being thus prepared, must
+be laid face to face, and hinged together so that they may be
+made to open and shut at pleasure like the leaves of a book.”
+After showing how various figures are to be looked at in these
+glasses under the same opening, and how the same figure may
+be varied under the different openings, the ingenious artist thus
+concludes: “If it should happen that the reader has any number
+of plans for parterres or wildernesses by him, he may by this
+method alter them at his pleasure, and produce such innumerable
+varieties as it is not possible the most able designer could
+ever have contrived.”</p>
+
+<h3>MAGIC OF PHOTOGRAPHY.</h3>
+
+<p>Professor Moser of Königsberg has discovered that all bodies,
+even in the dark, throw out invisible rays; and that these
+bodies, when placed at a small distance from polished surfaces
+of all kinds, depict themselves upon such surfaces in forms
+which remain invisible till they are developed by the human
+breath or by the vapours of mercury or iodine. Even if the
+sun’s image is made to pass over a plate of glass, the light
+tread of its rays will leave behind it an invisible track, which
+the human breath will instantly reveal.</p>
+
+<blockquote>
+
+<p>Among the early attempts to take pictures by the rays of the sun
+was a very interesting and successful experiment made by Dr. Thomas
+Young. In 1802, when Mr. Wedgewood was “making profiles by the
+agency of light,” and Sir Humphry Davy was “copying on prepared
+paper the images of small objects produced by means of the solar microscope,”
+Dr. Young was taking photographs upon paper dipped in a solution
+of nitrate of silver, of the coloured rings observed by Newton;
+and his experiments clearly proved that the agent was not the luminous
+rays in the sun’s light, but the invisible or chemical rays beyond the
+violet. This experiment is described in the Bakerian Lecture, 1803.</p>
+
+<p>Niepce (says Mr. Hunt) pursued a physical investigation of the curious
+change, and found that all bodies were influenced by this principle
+radiated from the sun. Daguerre<a name="FNanchor_14" id="FNanchor_14" href="#Footnote_14" class="fnanchor">14</a> produced effects from the solar pencil
+which no artist could approach; and Talbot and others extended the
+application. Herschel took up the inquiry; and he, with his usual<span class="pagenum"><a name="Page_45" id="Page_45">45</a></span>
+power of inductive search and of philosophical deduction, presented the
+world with a class of discoveries which showed how vast a field of investigation
+was opening for the younger races of mankind.</p>
+
+<p>The first attempts in photography, which were made at the instigation
+of M. Arago, by order of the French Government, to copy the
+Egyptian tombs and temples and the remains of the Aztecs in Central
+America, were failures. Although the photographers employed succeeded
+to admiration, in Paris, in producing pictures in a few minutes,
+they found often that an exposure of an hour was insufficient under the
+bright and glowing illumination of a southern sky.</p></blockquote>
+
+<h3>THE BEST SKY FOR PHOTOGRAPHY.</h3>
+
+<p>Contrary to all preconceived ideas, experience proves that
+the brighter the sky that shines above the camera the more
+tardy the action within it. Italy and Malta do their work
+slower than Paris. Under the brilliant light of a Mexican sun,
+half an hour is required to produce effects which in England
+would occupy but a minute. In the burning atmosphere of
+India, though photographical the year round, the process is
+comparatively slow and difficult to manage; while in the clear,
+beautiful, and moreover cool, light of the higher Alps of Europe,
+it has been proved that the production of a picture requires
+many more minutes, even with the most sensitive preparations,
+than in the murky atmosphere of London. Upon
+the whole, the temperate skies of this country may be pronounced
+favourable to photographic action; a fact for which
+the prevailing characteristic of our climate may partially account,
+humidity being an indispensable condition for the
+working state both of paper and chemicals.&mdash;<i>Quarterly Review</i>,
+No. 202.</p>
+
+<h3>PHOTOGRAPHIC EFFECTS OF LIGHTNING.</h3>
+
+<p>The following authenticated instances of this singular phenomenon
+have been communicated to the Royal Society by
+Andrés Poey, Director of the Observatory at Havana:</p>
+
+<blockquote>
+
+<p>Benjamin Franklin, in 1786, stated that about twenty years previous,
+a man who was standing opposite a tree that had just been struck
+by “a thunderbolt” had on his breast an exact representation of that
+tree.</p>
+
+<p>In the New-York <i>Journal of Commerce</i>, August 26th, 1853, it is related
+that “a little girl was standing at a window, before which was a
+young maple-tree; after a brilliant flash of lightning, a complete image
+of the tree was found imprinted on her body.”</p>
+
+<p>M. Raspail relates that, in 1855, a boy having climbed a tree for
+the purpose of robbing a bird’s nest, the tree was struck, and the boy
+thrown upon the ground; on his breast the image of the tree, with the
+bird and nest on one of its branches, appeared very plainly.</p>
+
+<p>M. Olioli, a learned Italian, brought before the Scientific Congress
+at Naples the following four instances: 1. In September 1825, the foremast
+of a brigantine in the Bay of St. Arniro was struck by lightning,
+when a sailor sitting under the mast was struck dead, and on his back<span class="pagenum"><a name="Page_46" id="Page_46">46</a></span>
+was found an impression of a horse-shoe, similar even in size to that
+fixed on the mast-head. 2. A sailor, standing in a similar position,
+was struck by lightning, and had on his left breast the impression of the
+number 4 4, with a dot between the two figures, just as they appeared at
+the extremity of one of the masts. 3. On the 9th October 1836, a young
+man was found struck by lightning; he had on a girdle, with some gold
+coins in it, which were imprinted on his skin in the order they were
+placed in the girdle,&mdash;a series of circles, with one point of contact, being
+plainly visible. 4. In 1847, Mme. Morosa, an Italian lady of Lugano,
+was sitting near a window during a thunderstorm, and perceived the
+commotion, but felt no injury; but a flower which happened to be in
+the path of the electric current was perfectly reproduced on one of her
+legs, and there remained permanently.</p>
+
+<p>M. Poey himself witnessed the following instance in Cuba. On July
+24th, 1852, a poplar-tree in a coffee-plantation was struck by lightning,
+and on one of the large dry leaves was found an exact representation
+of some pine-trees that lay 367 yards distant.</p></blockquote>
+
+<p>M. Poey considers these lightning impressions to have
+been produced in the same manner as the electric images obtained
+by Moser, Riess, Karster, Grove, Fox Talbot, and others,
+either by statical or dynamical electricity of different intensities.
+The fact that impressions are made through the garments
+is easily accounted for by their rough texture not preventing
+the lightning passing through them with the impression.
+To corroborate this view, M. Poey mentions an instance
+of lightning passing down a chimney into a trunk, in which
+was found an inch depth of soot, which must have passed
+through the wood itself.</p>
+
+<h3>PHOTOGRAPHIC SURVEYING.</h3>
+
+<p>During the summer of 1854, in the Baltic, the British
+steamers employed in examining the enemy’s coasts and fortifications
+took photographic views for reference and minute
+examination. With the steamer moving at the rate of fifteen
+knots an hour, the most perfect definitions of coasts and batteries
+were obtained. Outlines of the coasts, correct in height
+and distance, have been faithfully transcribed; and all details
+of the fortresses passed under this photographic review are accurately
+recorded.</p>
+
+<blockquote>
+
+<p>It is curious to reflect that the aids to photographic development all
+date within the last half-century, and are but little older than photography
+itself. It was not until 1811 that the chemical substance called
+iodine, on which the foundations of all popular photography rest, was
+discovered at all; bromine, the only other substance equally sensitive,
+not till 1826. The invention of the electro process was about simultaneous
+with that of photography itself. Gutta-percha only just preceded
+the substance of which collodion is made; the ether and chloroform,
+which are used in some methods, that of collodion. We say
+nothing of the optical improvements previously contrived or adapted
+for the purpose of the photograph: the achromatic lenses, which correct
+the discrepancy between the visual and chemical foci; the double<span class="pagenum"><a name="Page_47" id="Page_47">47</a></span>
+lenses, which increase the force of the action; the binocular lenses,
+which do the work of the stereoscope; nor of the innumerable other
+mechanical aids which have sprung up for its use.</p></blockquote>
+
+<h3>THE STEREOSCOPE AND THE PHOTOGRAPH.</h3>
+
+<p>When once the availability of one great primitive agent
+is worked out, it is easy to foresee how extensively it will assist
+in unravelling other secrets in natural science. The simple
+principle of the Stereoscope, for instance, might have been
+discovered a century ago, for the reasoning which led to it
+was independent of all the properties of light; but it could
+never have been illustrated, far less multiplied as it now is,
+without Photography. A few diagrams, of sufficient identity
+and difference to prove the truth of the principle, might have
+been constructed by hand, for the gratification of a few sages;
+but no artist, it is to be hoped, could have been found possessing
+the requisite ability and stupidity to execute the two portraits,
+or two groups, or two interiors, or two landscapes, identical in
+every minutia of the most elaborate detail, and yet differing
+in point of view by the inch between the two human eyes, by
+which the principle is brought to the level of any capacity.
+Here, therefore, the accuracy and insensibility of a machine
+could alone avail; and if in the order of things the cheap popular
+toy which the stereoscope now represents was necessary for
+the use of man, the photograph was first necessary for the service
+of the stereoscope.&mdash;<i>Quarterly Review</i>, No. 202.</p>
+
+<h3>THE STEREOSCOPE SIMPLIFIED.</h3>
+
+<p>When we look at any round object, first with one eye, and
+then with the other, we discover that with the right eye we
+see most of the right-hand side of the object, and with the left
+eye most of the left-hand side. These two images are combined,
+and we see an object which we know to be round.</p>
+
+<p>This is illustrated by the <i>Stereoscope</i>, which consists of two
+mirrors placed each at an angle of 45 deg., or of two semi-lenses
+turned with their curved sides towards each other. To view
+its phenomena two pictures are obtained by the camera on photographic
+paper of any object in two positions, corresponding
+with the conditions of viewing it with the two eyes. By the
+mirrors on the lenses these dissimilar pictures are combined
+within the eye, and the vision of an actually solid object is
+produced from the pictures represented on a plane surface.
+Hence the name of the instrument, which signifies <i>Solid I see</i>.&mdash;<i>Hunt’s
+Poetry of Science.</i></p>
+
+<h3>PHOTO-GALVANIC ENGRAVING.</h3>
+
+<p>That which was the chief aid of Niepce in the humblest
+dawn of the art, viz. to transform the photographic plate into<span class="pagenum"><a name="Page_48" id="Page_48">48</a></span>
+a surface capable of being printed, is in the above process
+done by the coöperation of Electricity with Photography. This
+invention of M. Pretsch, of Vienna, differs from all other
+attempts for the same purpose in not operating upon the photographic
+tablet itself, and by discarding the usual means of
+varnishes and bitings-in. The process is simply this: A glass
+tablet is coated with gelatine diluted till it forms a jelly, and
+containing bi-chromate of potash, nitrate of silver, and iodide
+of potassium. Upon this, when dry, is placed face downwards
+a paper positive, through which the light, being allowed to
+fall, leaves upon the gelatine a representation of the print. It
+is then soaked in water; and while the parts acted upon by the
+light are comparatively unaffected by the fluid, the remainder
+of the jelly swells, and rising above the general surface, gives
+a picture in relief, resembling an ordinary engraving upon
+wood. Of this intaglio a cast is now taken in gutta-percha,
+to which the electro process in copper being applied, a plate
+or matrix is produced, bearing on it an exact repetition of
+the original positive picture. All that now remains to be done
+is to repeat the electro process; and the result is a copper-plate
+in the necessary relievo, of which it has been said nature furnished
+the materials and science the artist, the inferior workman
+being only needed to roll it through the press.&mdash;<i>Quarterly
+Review</i>, No. 202.</p>
+
+<h3>SCIENCE OF THE SOAP-BUBBLE.</h3>
+
+<p>Few of the minor ingenuities of mankind have amused so
+many individuals as the blowing of bubbles with soap-lather
+from the bowl of a tobacco-pipe; yet how few who in childhood’s
+careless hours have thus amused themselves, have in
+after-life become acquainted with the beautiful phenomena of
+light which the soap-bubble will enable us to illustrate!</p>
+
+<p>Usually the bubble is formed within the bowl of a tobacco-pipe,
+and so inflated by blowing through the stem. It is also
+produced by introducing a capillary tube under the surface of
+soapy water, and so raising a bubble, which may be inflated to
+any convenient size. It is then guarded with a glass cover, to
+prevent its bursting by currents of air, evaporation, and other
+causes.</p>
+
+<p>When the bubble is first blown, its form is elliptical, into
+which it is drawn by its gravity being resisted; but the instant
+it is detached from the pipe, and allowed to float in air, it becomes
+a perfect sphere, since the air within presses equally in
+all directions. There is also a strong cohesive attraction in
+the particles of soap and water, after having been forcibly distended;
+and as a sphere or globe possesses less surface than
+any other figure of equal capacity, it is of all forms the best<span class="pagenum"><a name="Page_49" id="Page_49">49</a></span>
+adapted to the closest approximation of the particles of soap
+and water, which is another reason why the bubble is globular.
+The film of which the bubble consists is inconceivably thin
+(not exceeding the two-millionth part of an inch); and by the
+evaporation from its surface, the contraction and expansion of
+the air within, and the tendency of the soap-lather to gravitate
+towards the lower part of the bubble, and consequently to render
+the upper part still thinner, it follows that the bubble lasts
+but a few seconds. If, however, it were blown in a glass vessel,
+and the latter immediately closed, it might remain for some
+time; Dr. Paris thus preserved a bubble for a considerable period.</p>
+
+<p>Dr. Hooke, by means of the coloured rings upon the soap-bubble,
+studied the curious subject of the colours of thin plates,
+and its application to explain the colours of natural bodies.
+Various phenomena were also discovered by Newton, who thus
+did not disdain to make a soap-bubble the object of his study.
+The colours which are reflected from the upper surface of the
+bubble are caused by the decomposition of the light which falls
+upon it; and the range of the phenomena is alike extensive and
+beautiful.<a name="FNanchor_15" id="FNanchor_15" href="#Footnote_15" class="fnanchor">15</a></p>
+
+<p>Newton (says Sir D. Brewster), having covered the soap-bubble
+with a glass shade, saw its colours emerge in regular
+order, like so many concentric rings encompassing the top of
+it. As the bubble grew thinner by the continual subsidence
+of the water, the rings dilated slowly, and overspread the whole
+of it, descending to the bottom, where they vanished successively.
+When the colours had all emerged from the top, there
+arose in the centre of the rings a small round black spot, dilating
+it to more than half an inch in breadth till the bubble
+burst. Upon examining the rings between the object-glasses,
+Newton found that when they were only <i>eight</i> or <i>nine</i> in number,
+more than <i>forty</i> could be seen by viewing them through a
+prism; and even when the plate of air seemed all over uniformly
+white, multitudes of rings were disclosed by the prism.
+By means of these observations Newton was enabled to form
+his <i>Scale of Colours</i>, of great value in all optical researches.</p>
+
+<p>Dr. Reade has thus produced a permanent soap-bubble:</p>
+
+<blockquote>
+
+<p>Put into a six-ounce phial two ounces of distilled water, and set
+the phial in a vessel of water boiling on the fire. The water in the
+phial will soon boil, and steam will issue from its mouth, expelling the
+whole of the atmospheric air from within. Then throw in a piece of
+soap about the size of a small pea, cork the phial, and at the same instant<span class="pagenum"><a name="Page_50" id="Page_50">50</a></span>
+remove it and the vessel from the fire. Then press the cork farther
+into the neck of the phial, and cover it thickly with sealing-wax;
+and when the contents are cold, a perfect vacuum will be formed within
+the bottle,&mdash;much better, indeed, than can be produced by the best-constructed
+air-pump.</p>
+
+<p>To form a bubble, hold the bottle horizontally in both hands, and
+give it a sudden upward motion, which will throw the liquid into a wave,
+whose crest touching the upper interior surface of the phial, the tenacity
+of the liquid will cause a film to be retained all round the phial. Next
+place the phial on its bottom; when the film will form a section of the
+cylinder, being nearly but never quite horizontal. The film will be now
+colourless, since it reflects all the light which falls upon it. By remaining
+at rest for a minute or two, minute currents of lather will descend
+by their gravitating force down the inclined plane formed by the
+film, the upper part of which thus becomes drained to the necessary
+thinness; and this is the part to be observed.</p></blockquote>
+
+<p>Several concentric segments of coloured rings are produced;
+the colours, beginning from the top, being as follows:</p>
+
+<p class="in0 in4">
+<i>1st order</i>: Black, white, yellow, orange, red.<br />
+<i>2d order</i>: Purple, blue, white, yellow, red.<br />
+<i>3d order</i>: Purple, blue, green, yellowish-green, white, red.<br />
+<i>4th order</i>: Purple, blue, green, white, red.<br />
+<i>5th order</i>: Greenish-blue, very pale red.<br />
+<i>6th order</i>: Greenish-blue, pink.<br />
+<i>7th order</i>: Greenish-blue, pink.
+</p>
+
+<p class="in0">As the segments advance they get broader, while the film becomes
+thinner and thinner. The several orders disappear upwards
+as the film becomes too thin to reflect their colours,
+until the first order alone remains, occupying the whole surface
+of the film. Of this order the red disappears first, then the
+orange, and lastly the yellow. The film is now divided by a
+line into two nearly equal portions, one black and the other
+white. This remains for some time; at length the film becomes
+too thin to hold together, and then vanishes. The colours are
+not faint and imperfect, but well defined, glowing with gorgeous
+hues, or melting into tints so exquisite as to have no
+rival through the whole circle of the arts. We quote these details
+from Mr. Tomlinson’s excellent <i>Student’s Manual of Natural
+Philosophy</i>.</p>
+
+<blockquote>
+
+<p>We find the following anecdote related of Newton at the above
+period. When Sir Isaac changed his residence, and went to live in
+St. Martin’s Street, Leicester Square, his next-door neighbour was a
+widow lady, who was much puzzled by the little she observed of the
+habits of the philosopher. A Fellow of the Royal Society called upon
+her one day, when, among her domestic news, she mentioned that some
+one had come to reside in the adjoining house who, she felt certain, was
+a poor crazy gentleman, “because,” she continued, “he diverts himself
+in the oddest way imaginable. Every morning, when the sun shines so
+brightly that we are obliged to draw the window-blinds, he takes his
+seat on a little stool before a tub of soapsuds, and occupies himself for
+hours blowing soap-bubbles through a common clay-pipe, which bubbles<span class="pagenum"><a name="Page_51" id="Page_51">51</a></span>
+he intently watches floating about till they burst. He is doubtless,” she
+added, “now at his favourite amusement, for it is a fine day; do come
+and look at him.” The gentleman smiled, and they went upstairs;
+when, after looking through the staircase-window into the adjoining
+court-yard, he turned and said: “My dear madam, the person whom
+you suppose to be a poor lunatic is no other than the great Sir Isaac
+Newton studying the refraction of light upon thin plates; a phenomenon
+which is beautifully exhibited on the surface of a common soap-bubble.”</p></blockquote>
+
+<h3>LIGHT FROM QUARTZ.</h3>
+
+<p>Among natural phenomena (says Sir David Brewster) illustrative
+of the colours of thin plates, we find none more remarkable
+than one exhibited by the fracture of a large crystal of
+quartz of a smoky colour, and about two and a quarter inches
+in diameter. The surface of fracture, in place of being a face
+or cleavage, or irregularly conchoidal, as we have sometimes
+seen it, was filamentous, like a surface of velvet, and consisted
+of short fibres, so small as to be incapable of reflecting light.
+Their size could not have been greater than the third of the
+millionth part of an inch, or one-fourth of the thinnest part of
+the soap-bubble when it exhibits the black spot where it bursts.</p>
+
+<h3>CAN THE CAT SEE IN THE DARK?</h3>
+
+<p>No, in all probability, says the reader; but the opposite
+popular belief is supported by eminent naturalists.</p>
+
+<blockquote>
+
+<p>Buffon says: “The eyes of the cat shine in the dark somewhat like
+diamonds, which throw out during the night the light with which they
+were in a manner impregnated during the day.”</p>
+
+<p>Valmont de Bamare says: “The pupil of the cat is during the night
+still deeply imbued with the light of the day;” and again, “the eyes of
+the cat are during the night so imbued with light that they then appear
+very shining and luminous.”</p>
+
+<p>Spallanzani says: “The eyes of cats, polecats, and several other animals,
+shine in the dark like two small tapers;” and he adds that this
+light is phosphoric.</p>
+
+<p>Treviranus says: “The eyes of the cat <i>shine where no rays of light
+penetrate</i>; and the light must in many, if not in all, cases proceed from
+the eye itself.”</p></blockquote>
+
+<p>Now, that the eyes of the cat do shine in the dark is to a
+certain extent true: but we have to inquire whether by <i>dark</i>
+is meant the entire absence of light; and it will be found that
+the solution of this question will dispose of several assertions
+and theories which have for centuries perplexed the subject.</p>
+
+<p>Dr. Karl Ludwig Esser has published in Karsten’s Archives
+the results of an experimental inquiry on the luminous appearance
+of the eyes of the cat and other animals, carefully distinguishing
+such as evolve light from those which only reflect it.
+Having brought a cat into a half-darkened room, he observed
+from a certain direction that the cat’s eyes, when <i>opposite the<span class="pagenum"><a name="Page_52" id="Page_52">52</a></span>
+window</i>, sparkled brilliantly; but in other positions the light
+suddenly vanished. On causing the cat to be held so as to exhibit
+the light, and then gradually darkening the room, the
+light disappeared by the time the room was made quite dark.</p>
+
+<p>In another experiment, a cat was placed opposite the window
+in a darkened room. A few rays were permitted to enter,
+and by adjusting the light, one or both of the cat’s eyes were
+made to shine. In proportion as the pupil was dilated, the eyes
+were brilliant. By suddenly admitting a strong glare of light
+into the room, the pupil contracted; and then suddenly darkening
+the room, the eye exhibited a small round luminous point,
+which enlarged as the pupil dilated.</p>
+
+<p>The eyes of the cat sparkle most when the animal is in a
+lurking position, or in a state of irritation. Indeed, the eyes
+of all animals, as well as of man, appear brighter when in rage
+than in a quiescent state, which Collins has commemorated in
+his Ode on the Passions:</p>
+
+<div class="poem-container">
+<div class="poem"><div class="stanza">
+<span class="iq">“Next Anger rushed, his eyes on fire.”<br /></span>
+</div></div>
+</div>
+
+<p class="in0">This brilliancy is said to arise from an increased secretion of the
+lachrymal fluid on the surface of the eye, by which the reflection
+of the light is increased. Dr. Esser, in places absolutely
+dark, never discovered the slightest trace of light in the eye
+of the cat; and he has no doubt that in all cases where cats’
+eyes have been seen to shine in dark places, such as a cellar,
+light penetrated through some window or aperture, and fell
+upon the eyes of the animal as it turned towards the opening,
+while the observer was favourably situated to obtain a view of
+the reflection.</p>
+
+<p>To prove more clearly that this light does not depend upon
+the will of the animal, nor upon its angry passions, experiments
+were made upon the head of a dead cat. The sun’s rays were
+admitted through a small aperture; and falling immediately
+upon the eyes, caused them to glow with a beautiful green light
+more vivid even than in the case of a living animal, on account
+of the increased dilatation of the pupil. It was also remarked
+that black and fox-coloured cats gave a brighter light than
+gray and white cats.</p>
+
+<p>To ascertain the cause of this luminous appearance Dr. Esser
+dissected the eyes of cats, and exposed them to a small regulated
+amount of light after having removed different portions.
+The light was not diminished by the removal of the
+cornea, but only changed in colour. The light still continued
+after the iris was displaced; but on taking away the crystalline
+lens it greatly diminished both in intensity and colour. Dr.
+Esser then conjectured that the tapetum in the hinder part of
+the eye must form a spot which caused the reflection of the<span class="pagenum"><a name="Page_53" id="Page_53">53</a></span>
+incident rays of light, and thus produce the shining; and this
+appeared more probable as the light of the eye now seemed to
+emanate from a single spot. Having taken away the vitreous
+humour, Dr. Esser observed that the entire want of the pigment
+in the hinder part of the choroid coat, where the optic nerve
+enters, formed a greenish, silver-coloured, changeable oblong
+spot, which was not symmetrical, but surrounded the optic
+nerve so that the greater part was above and only the smaller
+part below it; wherefore the greater part lay beyond the axis
+of vision. It is this spot, therefore, that produces the reflection
+of the incident rays of light, and beyond all doubt, according
+to its tint, contributes to the different colouring of the light.</p>
+
+<p>It may be as well to explain that the interior of the eye is
+coated with a black pigment, which has the same effect as the
+black colour given to the inner surface of optical instruments:
+it absorbs any rays of light that may be reflected within the eye,
+and prevents them from being thrown again upon the retina
+so as to interfere with the distinctness of the images formed
+upon it. The retina is very transparent; and if the surface behind
+it, instead of being of a dark colour, were capable of reflecting
+light, the luminous rays which had already acted on
+the retina would be reflected back again through it, and not
+only dazzle from excess of light, but also confuse and render
+indistinct the images formed on the retina. Now in the case
+of the cat this black pigment, or a portion of it, is wanting; and
+those parts of the eye from which it is absent, having either a
+white or a metallic lustre, are called the tapetum. The smallest
+portion of light entering from it is reflected as by a concave
+mirror; and hence it is that the eyes of animals provided with
+this structure are luminous in a very faint light.</p>
+
+<p>These experiments and observations show that the shining
+of the eyes of the cat does not arise from a phosphoric light,
+but only from a reflected light; that consequently it is not an
+effect of the will of the animal, or of violent passions; that
+their shining does not appear in absolute darkness; and that
+it cannot enable the animal to move securely in the dark.</p>
+
+<p>It has been proved by experiment that there exists a set of
+rays of light of far higher refrangibility than those seen in the
+ordinary Newtonian spectrum. Mr. Hunt considers it probable
+that these highly refrangible rays, although under ordinary
+circumstances invisible to the human eye, may be adapted to
+produce the necessary degree of excitement upon which vision
+depends in the optic nerves of the night-roaming animals. The
+bat, the owl, and the cat may see in the gloom of the night
+by the aid of rays which are invisible to, or inactive on, the
+eyes of man or those animals which require the light of day
+for perfect vision.</p>
+
+<hr />
+
+<p><span class="pagenum"><a name="Page_54" id="Page_54">54</a></span></p>
+
+<div class="chapter"></div>
+<h2><a name="Astronomy" id="Astronomy"></a>Astronomy.</h2>
+
+<h3>THE GREAT TRUTHS OF ASTRONOMY.</h3>
+
+<p>The difficulty of understanding these marvellous truths has
+been glanced at by an old divine (see <i>Things not generally
+Known</i>, p. 1); but the rarity of their full comprehension by
+those unskilled in mathematical science is more powerfully
+urged by Lord Brougham in these cogent terms:</p>
+
+<blockquote>
+
+<p>Satisfying himself of the laws which regulate the mutual actions of
+the planetary bodies, the mathematician can convince himself of a truth
+yet more sublime than Newton’s discovery of gravitation, though flowing
+from it; and must yield his assent to the marvellous position, that
+all the irregularities occasioned in the system of the universe by the
+mutual attraction of its members are periodical, and subject to an eternal
+law, which prevents them from ever exceeding a stated amount, and
+secures through all time the balanced structure of a universe composed
+of bodies whose mighty bulk and prodigious swiftness of motion mock
+the utmost efforts of the human imagination. All these truths are to
+the skilful mathematician as thoroughly known, and their evidence is as
+clear, as the simplest proposition of arithmetic to common understandings.
+But how few are those who thus know and comprehend them!
+Of all the millions that thoroughly believe these truths, certainly not a
+thousand individuals are capable of following even any considerable portion
+of the demonstrations upon which they rest; and probably not a
+hundred now living have ever gone through the whole steps of these
+demonstrations.&mdash;<i>Dissertations on Subjects of Science connected with
+Natural Theology</i>, vol. ii.</p></blockquote>
+
+<p>Sir David Brewster thus impressively illustrates the same
+subject:</p>
+
+<blockquote>
+
+<p>Minds fitted and prepared for this species of inquiry are capable of
+appreciating the great variety of evidence by which the truths of the
+planetary system are established; but thousands of individuals, and
+many who are highly distinguished in other branches of knowledge, are
+incapable of understanding such researches, and view with a sceptical
+eye the great and irrefragable truths of astronomy.</p>
+
+<p>That the sun is stationary in the centre of our system; that the earth
+moves round the sun, and round its own axis; that the diameter of
+the earth is 8000 miles, and that of the sun <i>one hundred and ten times
+as great</i>; that the earth’s orbit is 190,000,000 of miles in breadth; and
+that if this immense space were filled with light, it would appear only
+like a luminous point at the nearest fixed star,&mdash;are positions absolutely
+unintelligible and incredible to all who have not carefully studied the
+subject. To millions of our species, then, the great Book of Nature is
+absolutely sealed; though it is in the power of all to unfold its pages, and
+to peruse those glowing passages which proclaim the power and wisdom
+of its Author.</p></blockquote>
+
+<p><span class="pagenum"><a name="Page_55" id="Page_55">55</a></span></p>
+
+<h3>ASTRONOMY AND DATES ON MONUMENTS.</h3>
+
+<p>Astronomy is a useful aid in discovering the Dates of ancient
+Monuments. Thus, on the ceiling of a portico among the ruins
+of Tentyris are the twelve signs of the Zodiac, placed according
+to the apparent motion of the sun. According to this Zodiac,
+the summer solstice is in Leo; from which it is easy to compute,
+by the precession of the equinoxes of 50″·1 annually, that
+the Zodiac of Tentyris must have been made 4000 years ago.</p>
+
+<p>Mrs. Somerville relates that she once witnessed the ascertainment
+of the date of a Papyrus by means of astronomy. The
+manuscript was found in Egypt, in a mummy-case; and its antiquity
+was determined by the configuration of the heavens at
+the time of its construction. It proved to be a horoscope of the
+time of Ptolemy.</p>
+
+<h3>“THE CRYSTAL VAULT OF HEAVEN.”</h3>
+
+<p>This poetic designation dates back as far as the early period
+of Anaximenes; but the first clearly defined signification of the
+idea on which the term is based occurs in Empedocles. This
+philosopher regarded the heaven of the fixed stars as a solid
+mass, formed from the ether which had been rendered crystalline
+by the action of fire.</p>
+
+<p>In the Middle Ages, the fathers of the Church believed the
+firmament to consist of from seven to ten glassy strata, incasing
+each other like the different coatings of an onion. This
+supposition still keeps its ground in some of the monasteries of
+southern Europe, where Humboldt was greatly surprised to
+hear a venerable prelate express an opinion in reference to the
+fall of aerolites at Aigle, that the bodies we called meteoric
+stones with vitrified crusts were not portions of the fallen stone
+itself, but simply fragments of the crystal vault shattered by it
+in its fall.</p>
+
+<p>Empedocles maintained that the fixed stars were riveted to
+the crystal heavens; but that the planets were free and unconstrained.
+It is difficult to conceive how, according to Plato in
+the <i>Timæus</i>, the fixed stars, riveted as they are to solid spheres,
+could rotate independently.</p>
+
+<p>Among the ancient views, it may be mentioned that the
+equal distance at which the stars remained, while the whole vault
+of heaven seemed to move from east to west, had led to the
+idea of a firmament and a solid crystal sphere, in which Anaximenes
+(who was probably not much later than Pythagoras)
+had conjectured that the stars were riveted like nails.</p>
+
+<h3>MUSIC OF THE SPHERES.</h3>
+
+<p>The Pythagoreans, in applying their theory of numbers to<span class="pagenum"><a name="Page_56" id="Page_56">56</a></span>
+the geometrical consideration of the five regular bodies, to the
+musical intervals of tone which determine a word and form
+different kinds of sounds, extended it even to the system of
+the universe itself; supposing that the moving, and, as it were,
+vibrating planets, exciting sound-waves, must produce a <i>spheral
+music</i>, according to the harmonic relations of their intervals of
+space. “This music,” they add, “would be perceived by the
+human ear, if it was not rendered insensible by extreme familiarity,
+as it is perpetual, and men are accustomed to it from
+childhood.”</p>
+
+<blockquote>
+
+<p>The Pythagoreans affirm, in order to justify the reality of the tones
+produced by the revolution of the spheres, that hearing takes place only
+where there is an alternation of sound and silence. The inaudibility of
+the spheral music is also accounted for by its overpowering the senses.
+Aristotle himself calls the Pythagorean tone-myth pleasing and ingenious,
+but untrue.</p></blockquote>
+
+<p>Plato attempted to illustrate the tones of the universe in an
+agreeable picture, by attributing to each of the planetary spheres
+a syren, who, supported by the stern daughters of Necessity,
+the three Fates, maintain the eternal revolution of the world’s
+axis. Mention is constantly made of the harmony of the
+spheres, though generally reproachfully, throughout the writings
+of Christian antiquity and the Middle Ages, from Basil the
+Great to Thomas Aquinas and Petrus Alliacus.</p>
+
+<p>At the close of the sixteenth century, Kepler revived these
+musical ideas, and sought to trace out the analogies between
+the relations of tone and the distances of the planets; and Tycho
+Brahe was of opinion that the revolving conical bodies were
+capable of vibrating the celestial air (what we now call “resisting
+medium”) so as to produce tones. Yet Kepler, although he
+had talked of Venus and the Earth sounding sharp in aphelion
+and flat in perihelion, and the highest tone of Jupiter and that
+of Venus coinciding in flat accord, positively declared there
+to be “no such things as sounds among the heavenly bodies,
+nor is their motion so turbulent as to elicit noise from the attrition
+of the celestial air.” (See <i>Things not generally Known</i>, p. 44.)</p>
+
+<h3>“MORE WORLDS THAN ONE.”</h3>
+
+<p>Although this opinion was maintained incidentally by various
+writers both on astronomy<a name="FNanchor_16" id="FNanchor_16" href="#Footnote_16" class="fnanchor">16</a> and natural religion, yet M.<span class="pagenum"><a name="Page_57" id="Page_57">57</a></span>
+Fontenelle was the first individual who wrote a treatise on the
+<i>Plurality of Worlds</i>, which appeared in 1685, the year before the
+publication of Newton’s <i>Principia</i>. Fontenelle’s work consists
+of five chapters: 1. The earth is a planet which turns round
+its axis, and also round the sun. 2. The moon is a habitable
+world. 3. Particulars concerning the world in the moon, and
+that the other planets are also inhabited. 4. Particulars of the
+worlds of Venus, Mercury, Mars, Jupiter, and Saturn. 5. The
+fixed stars are as many suns, each of which illuminates a world.
+In a future edition, 1719, Fontenelle added, 6. New thoughts
+which confirm those in the preceding conversations, and the
+latest discoveries which have been made in the heavens. The
+next work on the subject was the <i>Theory of the Universe, or
+Conjectures concerning the Celestial Bodies and their Inhabitants</i>,
+1698, by Christian Huygens, the contemporary of Newton.</p>
+
+<p>The doctrine is maintained by almost all the distinguished
+astronomers and writers who have flourished since the true
+figure of the earth was determined. Giordano Bruna of Nola,
+Kepler, and Tycho Brahe, believed in it; and Cardinal Cusa
+and Bruno, before the discovery of binary systems among the
+stars, believed also that the stars were inhabited. Sir Isaac
+Newton likewise adopted the belief; and Dr. Bentley, Master
+of Trinity College, Cambridge, in his eighth sermon on the Confutation
+of Atheism from the origin and frame of the world,
+has ably maintained the same doctrine. In our own day we
+may number among its supporters the distinguished names of
+the Marquis de la Place, Sir William and Sir John Herschel,
+Dr. Chalmers, Isaac Taylor, and M. Arago. Dr. Chalmers maintains
+the doctrine in his <i>Astronomical Discourses</i>, which one
+Alexander Maxwell (who did not believe in the grand truths of
+astronomy) attempted to controvert, in 1820, in a chapter of a
+volume entitled <i>Plurality of Worlds</i>.</p>
+
+<p>Next appeared <i>Of a Plurality of Worlds</i>, attributed to the
+Rev. Dr. Whewell, Master of Trinity College, Cambridge; urging
+the theological not less than the scientific reasons for believing
+in the old tradition of a single world, and maintaining that “the
+earth is really the largest planetary body in the solar system,&mdash;its
+domestic hearth, and the only world in the universe.” “I
+do not pretend,” says Dr. Whewell, “to disprove the plurality of
+worlds; but I ask in vain for any argument which makes the
+doctrine probable.” “It is too remote from knowledge to be
+either proved or disproved.” Sir David Brewster has replied
+to Dr. Whewell’s Essay, in <i>More Worlds than One, the Creed
+of the Philosopher and the Hope of the Christian</i>, emphatically
+maintaining that analogy strongly countenances the idea of all
+the solar planets, if not all worlds in the universe, being peopled
+with creatures not dissimilar in being and nature to the<span class="pagenum"><a name="Page_58" id="Page_58">58</a></span>
+inhabitants of the earth. This view is supported in <i>Scientific
+Certainties of Planetary Life</i>, by T.&nbsp;C. Simon, who well treats one
+point of the argument&mdash;that mere distance of the planets from
+the central sun does not determine the condition as to light
+and heat, but that the density of the ethereal medium enters
+largely into the calculation. Mr. Simon’s general conclusion is,
+that “neither on account of deficient or excessive heat, nor with
+regard to the density of the materials, nor with regard to the force
+of gravity on the surface, is there the slightest pretext for supposing
+that all the planets of our system are not inhabited by
+intellectual creatures with animal bodies like ourselves,&mdash;moral
+beings, who know and love their great Maker, and who wait,
+like the rest of His creation, upon His providence and upon His
+care.” One of the leading points of Dr. Whewell’s Essay is, that
+we should not elevate the conjectures of analogy into the rank
+of scientific certainties; and that “the force of all the presumptions
+drawn from physical reasoning for the opinion of planets
+and stars being either inhabited or uninhabited is so small, that
+the belief of all thoughtful persons on this subject will be determined
+by moral, metaphysical, and theological considerations.”</p>
+
+<h3>WORLDS TO COME&mdash;ABODES OF THE BLEST.</h3>
+
+<p>Sir David Brewster, in his eloquent advocacy of the doctrine
+of “more worlds than one,” thus argues for their peopling:</p>
+
+<blockquote>
+
+<p>Man, in his future state of existence, is to consist, as at present,
+of a spiritual nature residing in a corporeal frame. He must live, therefore,
+upon a material planet, subject to all the laws of matter, and performing
+functions for which a material body is indispensable. We must
+consequently find for the race of Adam, if not races that may have
+preceded him, a material home upon which they may reside, or by
+which they may travel, by means unknown to us, to other localities in
+the universe. At the present hour, the inhabitants of the earth are nearly
+<i>a thousand millions</i>; and by whatever process we may compute the
+numbers that have existed before the present generation, and estimate
+those that are yet to inherit the earth, we shall obtain a population
+which the habitable parts of our globe could not possibly accommodate.
+If there is not room, then, on our earth for the millions of millions
+of beings who have lived and died upon its surface, and who may yet
+live and die during the period fixed for its occupation by man, we can
+scarcely doubt that their future abode must be on some of the primary
+or secondary planets of the solar system, whose inhabitants have ceased
+to exist like those on the earth, or upon planets in our own or in other
+systems which have been in a state of preparation, as our earth was,
+for the advent of intellectual life.</p></blockquote>
+
+<h3>“GAUGING THE HEAVENS.”</h3>
+
+<p>Sir William Herschel, in 1785, conceived the happy idea
+of counting the number of stars which passed at different<span class="pagenum"><a name="Page_59" id="Page_59">59</a></span>
+heights and in various directions over the field of view, of fifteen
+minutes in diameter, of his twenty-feet reflecting telescope.
+The field of view each time embraced only 1/833000th of
+the whole heavens; and it would therefore require, according
+to Struve, eighty-three years to gauge the whole sphere by a
+similar process.</p>
+
+<h3>VELOCITY OF THE SOLAR SYSTEM.</h3>
+
+<p>M. F. W. G. Struve gives as the splendid result of the
+united studies of MM. Argelander, O. Struve, and Peters,
+grounded on observations made at the three Russian observatories
+of Dorpat, Abo, and Pulkowa, “that the velocity of the
+motion of the solar system in space is such that the sun, with
+all the bodies which depend upon it, advances annually towards
+the constellation Hercules<a name="FNanchor_17" id="FNanchor_17" href="#Footnote_17" class="fnanchor">17</a> 1·623 times the radius of the
+earth’s orbit, or 33,550,000 geographical miles. The possible
+error of this last number amounts to 1,733,000 geographical
+miles, or to a <i>seventh</i> of the whole value. We may, then, wager
+400,000 to 1 that the sun has a proper progressive motion, and
+1 to 1 that it is comprised between the limits of thirty-eight
+and twenty-nine millions of geographical miles.”</p>
+
+<blockquote>
+
+<p>That is, taking 95,000,000 of English miles as the mean radius of
+the Earth’s orbit, we have 95 × 1·623 = 154·185 millions of miles; and
+consequently,</p>
+
+<table summary="Velocity of the Solar System">
+  <tr>
+    <td> </td>
+    <td class="tdl" colspan="2">English Miles.</td></tr>
+  <tr>
+    <td class="tdc">The velocity of the Solar System</td>
+    <td class="tdr lrpad">154,185,000</td>
+    <td class="tdl">in the year.</td></tr>
+  <tr>
+    <td class="tdc">”<span class="in4">”</span></td>
+    <td class="tdr lrpad">422,424</td>
+    <td class="tdl">in a day.</td></tr>
+  <tr>
+    <td class="tdc">”<span class="in4">”</span></td>
+    <td class="tdr lrpad">17,601</td>
+    <td class="tdl">in an hour.</td></tr>
+  <tr>
+    <td class="tdc">”<span class="in4">”</span></td>
+    <td class="tdr lrpad">293</td>
+    <td class="tdl">in a minute.</td></tr>
+  <tr>
+    <td class="tdc">”<span class="in4">”</span></td>
+    <td class="tdr lrpad">57</td>
+    <td class="tdl">in a second.</td></tr>
+</table>
+
+<p class="in0">The Sun and all his planets, primary and secondary, are therefore now
+in rapid motion round an invisible focus. To that now dark and mysterious
+centre, from which no ray, however feeble, shines, we may in
+another age point our telescopes, detecting perchance the great luminary
+which controls our system and bounds its path: into that vast
+orbit man, during the whole cycle of his race, may never be allowed to
+round.&mdash;<i>North-British Review</i>, No. 16.</p></blockquote>
+
+<h3>NATURE OF THE SUN.</h3>
+
+<p>M. Arago has found, by experiments with the polariscope,
+that the light of gaseous bodies is natural light when it issues
+from the burning surface; although this circumstance does not
+prevent its subsequent complete polarisation, if subjected to<span class="pagenum"><a name="Page_60" id="Page_60">60</a></span>
+suitable reflections or refractions. Hence we obtain <i>a most
+simple method of discovering the nature of the sun</i> at a distance
+of forty millions of leagues. For if the light emanating from
+the margin of the sun, and radiating from the solar substance
+<i>at an acute angle</i>, reach us without having experienced any
+sensible reflections or refractions in its passage to the earth,
+and if it offer traces of polarisation, the sun must be <i>a solid or
+a liquid body</i>. But if, on the contrary, the light emanating
+from the sun’s margin give no indications of polarisation, the
+<i>incandescent</i> portion of the sun must be <i>gaseous</i>. It is by means
+of such a methodical sequence of observations that we may
+acquire exact ideas regarding the physical constitution of the
+sun.&mdash;<i>Note to Humboldt’s Cosmos</i>, vol. iii.</p>
+
+<h3>STRUCTURE OF THE LUMINOUS DISC OF THE SUN.</h3>
+
+<p>The extraordinary structure of the <i>fully luminous</i> Disc of
+the Sun, as seen through Sir James South’s great achromatic,
+in a drawing made by Mr. Gwilt, resembles compressed curd,
+or white almond-soap, or a mass of asbestos fibres, lying in
+a <i>quaquaversus</i> direction, and compressed into a solid mass.
+There can be no illusion in this phenomenon; it is seen by
+every person with good vision, and on every part of the sun’s
+luminous surface or envelope, which is thus shown to be not
+a <i>flame</i>, but a soft solid or thick fluid, maintained in an incandescent
+state by subjacent heat, capable of being disturbed by
+differences of temperature, and broken up as we see it when
+the sun is covered with spots or openings in the luminous
+matter.&mdash;<i>North-British Review</i>, No. 16.</p>
+
+<blockquote>
+
+<p>Copernicus named the sun the lantern of the world (<i>lucerna mundi</i>);
+and Theon of Smyrna called it the heart of the universe. The mass of
+the sun is, according to Encke’s calculation of Sabine’s pendulum formula,
+359,551 times that of the earth, or 355,499 times that of the earth
+and moon together; whence the density of the sun is only about ¼ (or
+more accurately 0·252) that of the earth. The volume of the sun is
+600 times greater, and its mass, according to Galle, 738 times greater,
+than that of all the planets combined. It may assist the mind in conceiving
+a sensuous image of the magnitude of the sun, if we remember
+that if the solar sphere were entirely hollowed out, and the earth placed
+in its centre, there would still be room enough for the moon to describe
+its orbit, even if the radius of the latter were increased 160,000 geographical
+miles. A railway-engine, moving at the rate of thirty miles
+an hour, would require 360 years to travel from the earth to the sun.
+The diameter of the sun is rather more than one hundred and eleven
+times the diameter of the earth. Therefore the volume or bulk of the
+sun must be nearly <i>one million four hundred thousand</i> times that of the
+earth. Lastly, if all the bodies composing the solar system were formed
+into one globe, it would be only about the five-hundredth part of the
+size of the sun.</p></blockquote>
+
+<p><span class="pagenum"><a name="Page_61" id="Page_61">61</a></span></p>
+
+<h3>GREAT SIZE OF THE SUN ON THE HORIZON EXPLAINED.</h3>
+
+<p>The dilated size (generally) of the Sun or Moon, when seen
+near the horizon, beyond what they appear to have when high
+up in the sky, has nothing to do with refraction. It is an illusion
+of the judgment, arising from the terrestrial objects interposed,
+or placed in close comparison with them. In that situation
+we view and judge of them as we do of terrestrial objects&mdash;in
+detail, and with an acquired attention to parts. Aloft we
+have no association to guide us, and their insulation in the
+expanse of the sky leads us rather to undervalue than to over-rate
+their apparent magnitudes. Actual measurement with a
+proper instrument corrects our error, without, however, dispelling
+our illusion. By this we learn that the sun, when just
+on the horizon, subtends at our eyes almost exactly the same,
+and the moon a materially <i>less</i>, angle than when seen at a
+greater altitude in the sky, owing to its greater distance from
+us in the former situation as compared with the latter.&mdash;<i>Sir
+John Herschel’s Outlines.</i></p>
+
+<h3>TRANSLATORY MOTION OF THE SUN.</h3>
+
+<p>This phenomenon is the progressive motion of the centre
+of gravity of the whole solar system in universal space. Its
+velocity, according to Bessel, is probably four millions of miles
+daily, in a <i>relative</i> velocity to that of 61 Cygni of at least
+3,336,000 miles, or more than double the velocity of the revolution
+of the earth in her orbit round the sun. This change of the
+entire solar system would remain unknown to us, if the admirable
+exactness of our astronomical instruments of measurement,
+and the advancement recently made in the art of observing,
+did not cause our progress towards remote stars to be
+perceptible, like an approximation to the objects of a distant
+shore in apparent motion. The proper motion of the star 61
+Cygni, for instance, is so considerable, that it has amounted
+to a whole degree in the course of 700 years.&mdash;<i>Humboldt’s Cosmos</i>,
+vol. i.</p>
+
+<h3>THE SUN’S LIGHT COMPARED WITH TERRESTRIAL LIGHTS.</h3>
+
+<p>Mr. Ponton has by means of a simple monochromatic photometer
+ascertained that a small surface, illuminated by mean
+solar light, is 444 times brighter than when it is illuminated by
+a moderator lamp, and 1560 times brighter than when it is
+illuminated by a wax-candle (short six in the lb.)&mdash;the artificial
+light being in both instances placed at two inches’ distance
+from the illuminated surface. And three electric lights, each<span class="pagenum"><a name="Page_62" id="Page_62">62</a></span>
+equal to 520 wax-candles, will render a small surface as bright
+as when it is illuminated by mean sunshine.</p>
+
+<p>It is thence inferred, that a stratum occupying the entire
+surface of the sphere of which the earth’s distance from the
+sun is the radius, and consisting of three layers of flame, each
+1/1000th of an inch in thickness, each possessing a brightness
+equal to that of such an electric light, and all three embraced
+within a thickness of 1/40th of an inch, would give an amount
+of illumination equal in quantity and intensity to that of the
+sun at the distance of 95 millions of miles from his centre.</p>
+
+<p>And were such a stratum transferred to the surface of the
+sun, where it would occupy 46,275 times less area, its thickness
+would be increased to 94 feet, and it would embrace
+138,825 layers of flame, equal in brightness to the electric light;
+but the same effect might be produced by a stratum about
+nine miles in thickness, embracing 72 millions of layers, each
+having only a brightness equal to that of a wax-candle.<a name="FNanchor_18" id="FNanchor_18" href="#Footnote_18" class="fnanchor">18</a></p>
+
+<h3>ACTINIC POWER OF THE SUN.</h3>
+
+<p>Mr. J. J. Waterston, in 1857, made at Bombay some experiments
+on the photographic power of the sun’s direct light,
+to obtain data in an inquiry as to the possibility of measuring
+the diameter of the sun to a very minute fraction of a second,
+by combining photography with the principle of the electric
+telegraph; the first to measure the element space, the latter
+the element time. The result is that about 1/20000th of a second
+is sufficient exposure to the direct light of the sun to
+obtain a distinct mark on a sensitive collodion plate, when
+developed by the usual processes; and the duration of the
+sun’s full action on any one point is about 1/9000th of a second.</p>
+
+<p>M. Schatt, a young painter of Berlin, after 1500 experiments,
+succeeded in establishing a scale of all the shades of
+black which the action of the sun produces on photographic
+paper; so that by comparing the shade obtained at any given
+moment on a certain paper with that indicated on the scale,
+the exact force of the sun’s light may be determined.</p>
+
+<h3>HEATING POWER OF THE SUN.</h3>
+
+<p>All moving power has its origin in the rays of the sun.
+While Stephenson’s iron tubular railway-bridge over the Menai
+Straits, 400 feet long, bends but half an inch under the heaviest
+pressure of a train, it will bend up an inch and a half
+from its usual horizontal line when the sun shines on it for<span class="pagenum"><a name="Page_63" id="Page_63">63</a></span>
+some hours. The Bunker-Hill monument, near Boston, U.S.,
+is higher in the evening than in the morning of a sunny day;
+the little sunbeams enter the pores of the stone like so many
+wedges, lifting it up.</p>
+
+<p>In winter, the Earth is nearer the Sun by about 1/30 than in
+summer; but the rays strike the northern hemisphere more
+obliquely in winter than the other half year.</p>
+
+<p>M. Pouillet has estimated, with singular ingenuity, from a
+series of observations made by himself, that the whole quantity
+of heat which the Earth receives annually from the Sun is
+such as would be sufficient to melt a stratum of ice covering
+the entire globe forty-six feet deep.</p>
+
+<p>By the action of the sun’s rays upon the earth, vegetables,
+animals, and man, are in their turn supported; the rays become
+likewise, as it were, a store of heat, and “the sources of
+those great deposits of dynamical efficiency which are laid up
+for human use in our coal strata” (<i>Herschel</i>).</p>
+
+<p>A remarkable instance of the power of the sun’s rays is recorded
+at Stonehouse Point, Devon, in the year 1828. To lay
+the foundation of a sea-wall the workmen had to descend in a
+diving-bell, which was fitted with convex glasses in the upper
+part, by which, on several occasions in clear weather, the sun’s
+rays were so concentrated as to burn the labourers’ clothes
+when opposed to the focal point, and this when the bell was
+twenty-five feet under the surface of the water!</p>
+
+<h3>CAUSE OF DARK COLOUR OF THE SKIN.</h3>
+
+<p>Darkness of complexion has been attributed to the sun’s
+power from the age of Solomon to this day,&mdash;“Look not upon
+me, because I am black, because the sun hath looked upon
+me:” and there cannot be a doubt that, to a certain degree,
+the opinion is well founded. The invisible rays in the solar
+beams, which change vegetable colour, and have been employed
+with such remarkable effect in the daguerreotype, act
+upon every substance on which they fall, producing mysterious
+and wonderful changes in their molecular state, man not
+excepted.&mdash;<i>Mrs. Somerville.</i></p>
+
+<h3>EXTREME SOLAR HEAT.</h3>
+
+<p>The fluctuation in the sun’s direct heating power amounts
+to 1/15th, which is too considerable a fraction of the whole intensity
+not to aggravate in a serious degree the sufferings of
+those who are exposed to it in thirsty deserts without shelter.
+The amount of these sufferings, in the interior of Australia for
+instance, are of the most frightful kind, and would seem far to
+exceed what have ever been undergone by travellers in the<span class="pagenum"><a name="Page_64" id="Page_64">64</a></span>
+northern deserts of Africa. Thus Captain Sturt, in his account
+of his Australian exploration, says: “The ground was almost
+a molten surface; and if a match accidentally fell upon it, it
+immediately ignited.” Sir John Herschel has observed the
+temperature of the surface soil in South Africa as high as 159°
+Fahrenheit. An ordinary lucifer-match does not ignite when
+simply pressed upon a smooth surface at 212°; but <i>in the act
+of withdrawing it</i> it takes fire, and the slightest friction upon
+such a surface of course ignites it.</p>
+
+<h3>HOW DR. WOLLASTON COMPARED THE LIGHT OF THE SUN AND
+THE FIXED STARS.</h3>
+
+<p>In order to compare the Light of the Sun with that of a
+Star, Dr. Wollaston took as an intermediate object of comparison
+the light of a candle reflected from a bulb about a quarter
+of an inch in diameter, filled with quicksilver; and seen by one
+eye through a lens of two inches focus, at the same time that
+the star on the sun’s image, <i>placed at a proper distance</i>, was
+viewed by the other eye through a telescope. The mean of
+various trials seemed to show that the light of Sirius is equal
+to that of the sun seen in a glass bulb 1/10th of an inch in diameter,
+at the distance of 210 feet; or that they are in the
+proportion of one to ten thousand millions: but as nearly one
+half of this light is lost by reflection, the real proportion between
+the light from Sirius and the sun is not greater than
+that of one to twenty thousand millions.</p>
+
+<h3>“THE SUN DARKENED.”</h3>
+
+<p>Humboldt selects the following example from historical
+records as to the occurrence of a sudden decrease in the light
+of the Sun:</p>
+
+<blockquote>
+
+<p><span class="smcap smaller">A.D.</span> 33, the year of the Crucifixion. “Now from the sixth hour
+there was darkness over all the land till the ninth hour” (<i>St. Matthew</i>
+xxvii. 45). According to <i>St. Luke</i> (xxiii. 45), “the sun was darkened.”
+In order to explain and corroborate these narrations, Eusebius brings
+forward an eclipse of the sun in the 202d Olympiad, which had been
+noticed by the chronicler Phlegon of Tralles (<i>Ideler</i>, <i>Handbuch der
+Mathem. Chronologie</i>, Bd. ii. p. 417). Wurn, however, has shown that
+the eclipse which occurred during this Olympiad, and was visible over
+the whole of Asia Minor, must have happened as early as the 24th of
+November 29 <span class="smcap smaller">A.D.</span> The day of the Crucifixion corresponded with the
+Jewish Passover (<i>Ideler</i>, Bd. i. pp. 515&ndash;520), on the 14th of the month
+Nisan, and the Passover was always celebrated at the time of the <i>full
+moon</i>. The sun cannot therefore have been darkened for three hours by
+the moon. The Jesuit Scheiner thinks the decrease in the light might
+be ascribed to the occurrence of large sun-spots.</p></blockquote>
+
+<h3>THE SUN AND TERRESTRIAL MAGNETISM.</h3>
+
+<p>The important influence exerted by the Sun’s body, as a<span class="pagenum"><a name="Page_65" id="Page_65">65</a></span>
+mass, upon Terrestrial Magnetism, is confirmed by Sabine in
+the ingenious observation, that the period at which the intensity
+of the magnetic force is greatest, and the direction of the
+needle most near to the vertical line, falls in both hemispheres
+between the months of October and February; that is to say,
+precisely at the time when the earth is nearest to the sun, and
+moves in its orbit with the greatest velocity.</p>
+
+<h3>IS THE HEAT OF THE SUN DECREASING?</h3>
+
+<p>The Heat of the Sun is dissipated and lost by radiation, and
+must be progressively diminished unless its thermal energy be
+supplied. According to the measurements of M. Pouillet, the
+quantity of heat given out by the sun in a year is equal to that
+which would be produced by the combustion of a stratum of
+coal seventeen miles in thickness; and if the sun’s capacity for
+heat be assumed equal to that of water, and the heat be supposed
+drawn uniformly from its entire mass, its temperature
+would thereby undergo a diminution of 20·4° Fahr. annually.
+On the other hand, there is a vast store of force in our system
+capable of conversion into heat. If, as is indicated by the
+small density of the sun, and by other circumstances, that
+body has not yet reached the condition of incompressibility,
+we have in the future approximation of its parts a fund of
+heat, probably quite large enough to supply the wants of the
+human family to the end of its sojourn here. It has been calculated
+that an amount of condensation which would diminish
+the diameter of the sun by only the ten-thousandth part, would
+suffice to restore the heat emitted in 2000 years.</p>
+
+<h3>UNIVERSAL SUN-DIAL.</h3>
+
+<p>Mr. Sharp, of Dublin, exhibited to the British Association
+in 1849 a Dial, consisting of a cylinder set to the day of the
+month, and then elevated to the latitude. A thin plane of
+metal, in the direction of its axis, is then turned by a milled
+head below it till the shadow is a minimum, when a dial on
+the top shows the hours by one hand, and the minutes by another,
+to the precision of about three minutes.</p>
+
+<h3>LENGTH OF DAYS AT THE POLES.</h3>
+
+<p>During the summer, in the northern hemisphere, places
+near the North Pole are in <i>continual sunlight</i>&mdash;the sun never
+sets to them; while during that time places near the South
+Pole never see the sun. When it is summer in the southern
+hemisphere, and the sun shines on the South Pole without
+setting, the North Pole is entirely deprived of his light. Indeed,
+at the Poles there is but <i>one day and one night</i>; for the<span class="pagenum"><a name="Page_66" id="Page_66">66</a></span>
+sun shines for six months together on one Pole, and the other
+six months on the other Pole.</p>
+
+<h3>HOW THE DISTANCE OF THE SUN IS ASCERTAINED BY THE
+YARD-MEASURE.</h3>
+
+<p>Professor Airy, in his <i>Six Lectures on Astronomy</i>, gives a
+masterly analysis of a problem of considerable intricacy, viz.
+the determination of the parallax of the sun, and consequently
+of his distance, by observations of the transit of Venus, the connecting
+link between measures upon the earth’s surface and the
+dimensions of our system. The further step of investigating
+the parallax, and consequently the distance of the fixed stars
+(where that is practicable), is also elucidated; and the author,
+with evident satisfaction, thus sums up the several steps:</p>
+
+<blockquote>
+
+<p>By means of a yard-measure, a base-line in a survey was measured;
+from this, by the triangulations and computations of a survey, an arc of
+meridian on the earth was measured; from this, with proper observations
+with the zenith sector, the surveys being also repeated on different
+parts of the earth, the earth’s form and dimensions were ascertained;
+from these, and a previous independent knowledge of the proportions of
+the distances of the earth and other planets from the sun, with observations
+of the transit of Venus, the sun’s distance is determined; and from
+this, with observations leading to the parallax of the stars, the distance
+of the stars is determined. And <i>every step in the process can be distinctly
+referred to its basis, that is, the yard-measure</i>.</p></blockquote>
+
+<h3>HOW THE TIDES ARE PRODUCED BY THE SUN AND MOON.</h3>
+
+<p>Each of these bodies excites, by its attraction upon the
+waters of the sea, two gigantic waves, which flow in the same
+direction round the world as the attracting bodies themselves
+apparently do. The two waves of the moon, on account of
+her greater nearness, are about 3½ times as large as those excited
+by the sun. One of these waves has its crest on the
+quarter of the earth’s surface which is turned towards the
+moon; the other is at the opposite side. Both these quarters
+possess the flow of the tide, while the regions which lie between
+have the ebb. Although in the open sea the height of
+the tide amounts to only about three feet, and only in certain
+narrow channels, where the moving water is squeezed together,
+rises to thirty feet, the might of the phenomenon is nevertheless
+manifest from the calculation of Bessel, according to
+which a quarter of the earth covered by the sea possesses during
+the flow of the tide about 25,000 cubic miles of water
+more than during the ebb; and that, therefore, such a mass of
+water must in 6¼ hours flow from one quarter of the earth to
+the other.&mdash;<i>Professor Helmholtz.</i></p>
+
+<p><span class="pagenum"><a name="Page_67" id="Page_67">67</a></span></p>
+
+<h3>SPOTS ON THE SUN.</h3>
+
+<p>Sir John Herschel describes these phenomena, when watched
+from day to day, or even from hour to hour, as appearing to enlarge
+or contract, to change their forms, and at length disappear
+altogether, or to break out anew in parts of the surface where
+none were before. Occasionally they break up or divide into
+two or more. The scale on which their movements takes place
+is immense. A single second of angular measure, as seen from
+the earth, corresponds on the sun’s disc to 461 miles; and a
+circle of this diameter (containing therefore nearly 167,000
+square miles) is the least space which can be distinctly discerned
+on the sun as a <i>visible area</i>. Spots have been observed,
+however, whose linear diameter has been upwards of 45,000
+miles; and even, if some records are to be trusted, of very much
+greater extent. That such a spot should close up in six weeks
+time (for they seldom last much longer), its borders must approach
+at the rate of more than 1000 miles a-day.</p>
+
+<p>The same astronomer saw at the Cape of Good Hope, on the
+29th March 1837, a solar spot occupying an area of near <i>five
+square minutes</i>, equal to 3,780,000,000 square miles. “The
+black centre of the spot of May 25th, 1837 (not the tenth part
+of the preceding one), would have allowed the globe of our
+earth to drop through it, leaving a thousand miles clear of
+contact on all sides of that tremendous gulf.” For such an
+amount of disturbance on the sun’s atmosphere, what reason
+can be assigned?</p>
+
+<p>The Rev. Mr. Dawes has invented a peculiar contrivance,
+by means of which he has been enabled to scrutinise, under
+high magnifying power, minute portions of the solar disc. He
+places a metallic screen, pierced with a very small hole, in the
+focus of the telescope, where the image of the sun is formed.
+A small portion only of the image is thus allowed to pass
+through, so that it may be examined by the eye-piece without
+inconveniencing the observer by heat or glare. By this arrangement,
+Mr. Dawes has observed peculiarities in the constitution
+of the sun’s surface which are discernible in no other
+way.</p>
+
+<p>Before these observations, the dark spots seen on the sun’s
+surface were supposed to be portions of the solid body of the
+sun, laid bare to our view by those immense fluctuations in
+the luminous regions of its atmosphere to which it appears to
+be subject. It now appears that these dark portions are only
+an additional and inferior stratum of a very feebly luminous
+or illuminated portion of the sun’s atmosphere. This again in
+its turn Mr. Dawes has frequently seen pierced with a smaller
+and usually much more rounded aperture, which would seem<span class="pagenum"><a name="Page_68" id="Page_68">68</a></span>
+at last to afford a view of the real solar surface of most intense
+blackness.</p>
+
+<p>M. Schwabe, of Dessau, has discovered that the abundance
+or paucity of spots displayed by the sun’s surface is subject to
+a law of periodicity. This has been confirmed by M. Wolf, of
+Berne, who shows that the period of these changes, from minimum
+to minimum, is 11 years and 11-hundredths of a year,
+being exactly at the rate of nine periods per century, the last
+year of each century being a year of minimum. It is strongly
+corroborative of the correctness both of M. Wolf’s period and
+also of the periodicity itself, that of all the instances of the
+appearance of spots on the sun recorded in history, even before
+the invention of the telescope, or of remarkable deficiencies in
+the sun’s light, of which there are great numbers, only two are
+found to deviate as much as two years from M. Wolf’s epochs.
+Sir William Herschel observed that the presence or absence of
+spots had an influence on the temperature of the seasons; his
+observations have been fully confirmed by M. Wolf. And, from
+an examination of the chronicles of Zurich from <span class="smcap smaller">A.D.</span> 1000 to
+<span class="smcap smaller">A.D.</span> 1800, he has come to the conclusion “that years rich in
+solar spots are in general drier and more fruitful than those of
+an opposite character; while the latter are wetter and more
+stormy than the former.”</p>
+
+<p>The most extraordinary fact, however, in connection with
+the spots on the sun’s surface, is the singular coincidence of
+their periods with those great disturbances in the magnetic
+system of the earth to which the epithet of “magnetic storms”
+has been affixed.</p>
+
+<blockquote>
+
+<p>These disturbances, during which the magnetic needle is greatly
+and universally agitated (not in a particular limited locality, but at one
+and the same instant of time over whole continents, or even over the
+whole earth), are found, so far as observation has hitherto extended,
+to maintain a parallel, both in respect of their frequency of occurrence
+and intensity in successive years, with the abundance and magnitude
+of the spots in the same years, too close to be regarded as fortuitous.
+The coincidence of the epochs of maxima and minima in the two series
+of phenomena amounts, indeed, to identity; a fact evidently of most
+important significance, but which neither astronomical nor magnetic
+science is yet sufficiently advanced to interpret.&mdash;<i>Herschel’s Outlines.</i></p></blockquote>
+
+<p>The signification and connection of the above varying phenomena
+(Humboldt maintains) can never be manifested in their
+entire importance until an uninterrupted series of representations
+of the sun’s spots can be obtained by the aid of mechanical
+clock-work and photographic apparatus, as the result
+of prolonged observations during the many months of serene
+weather enjoyed in a tropical climate.</p>
+
+<blockquote>
+
+<p>M. Schwabe has thus distinguished himself as an indefatigable observer
+of the sun’s spots, for his researches received the Royal Astronomical<span class="pagenum"><a name="Page_69" id="Page_69">69</a></span>
+Society’s Medal in 1857. “For thirty years,” said the President
+at the presentation, “never has the sun exhibited his disc above the
+horizon of Dessau without being confronted by Schwabe’s imperturbable
+telescope; and that appears to have happened on an average about
+300 days a-year. So, supposing that he had observed but once a-day,
+he has made 9000 observations, in the course of which he discovered
+about 4700 groups. This is, I believe, an instance of devoted persistence
+unsurpassed in the annals of astronomy. The energy of one
+man has revealed a phenomenon that had eluded the suspicion of astronomers
+for 200 years.”</p></blockquote>
+
+<h3>HAS THE MOON AN ATMOSPHERE?</h3>
+
+<p>The Moon possesses neither Sea nor Atmosphere of appreciable
+extent. Still, as a negative, in such case, is relative only
+to the capabilities of the instruments employed, the search for
+the indications of a lunar atmosphere has been renewed with
+fresh augmentation of telescopic power. Of such indications,
+the most delicate, perhaps, are those afforded by the occultation
+of a planet by the moon. The occultation of Jupiter,
+which took place on January 2, 1857, was observed with this
+reference, and is said to have exhibited no <i>hesitation</i>, or change
+of form or brightness, such as would be produced by the refraction
+or absorption of an atmosphere. As respects the sea, if
+water existed on the moon’s surface, the sun’s light reflected
+from it should be completely polarised at a certain elongation
+of the moon from the sun; and no traces of such light have
+been observed.</p>
+
+<p>MM. Baer and Maedler conclude that the moon is not entirely
+without an atmosphere, but, owing to the smallness of
+her mass, she is incapacitated from holding an extensive covering
+of gas; and they add, “it is possible that this weak envelope
+may sometimes, through local causes, in some measure
+dim or condense itself.” But if any atmosphere exists on our
+satellite, it must be, as Laplace says, more attenuated than
+what is termed a vacuum in an air-pump.</p>
+
+<p>Mr. Hopkins thinks that if there be any lunar atmosphere,
+it must be very rare in comparison with the terrestrial atmosphere,
+and inappreciable to the kind of observation by which
+it has been tested; yet the absence of any refraction of the
+light of the stars during occultation is a very refined test. Mr.
+Nasmyth observes that “the sudden disappearance of the stars
+behind the moon, without any change or diminution of her
+brilliancy, is one of the most beautiful phenomena that can be
+witnessed.”</p>
+
+<p>Sir John Herschel observes: The fact of the moon turning
+always the same face towards the earth is, in all probability,
+the result of an elongation of its figure in the direction of a
+line joining the centres of both the bodies, acting conjointly<span class="pagenum"><a name="Page_70" id="Page_70">70</a></span>
+with a non-coincidence of its centre of gravity with its centre
+of symmetry.</p>
+
+<p>If to this we add the supposition that the substance of the
+moon is not homogeneous, and that some considerable preponderance
+of weight is placed excentrically in it, it will be
+easily apprehended that the portion of its surface nearer to that
+heavier portion of its solid content, under all the circumstances
+of the moon’s rotation, will permanently occupy the situation
+most remote from the earth.</p>
+
+<blockquote>
+
+<p>In what regards its assumption of a definite level, air obeys precisely
+the same hydrostatical laws as water. The lunar atmosphere would
+rest upon the lunar ocean, and form in its basin a lake of air, whose
+upper portions at an altitude such as we are now contemplating would
+be of excessive tenuity, especially should the provision of air be less
+abundant in proportion than our own. It by no means follows, then,
+from the absence of visible indications of water or air on this side of the
+moon, that the other is equally destitute of them, and equally unfitted
+for maintaining animal or vegetable life. Some slight approach to such
+a state of things actually obtains on the earth itself. Nearly all the
+land is collected in one of its hemispheres, and much the larger portion
+of the sea in the opposite. There is evidently an excess of heavy material
+vertically beneath the middle of the Pacific; while not very remote
+from the point of the globe diametrically opposite rises the great table-land
+of India and the Himalaya chain, on the summits of which the air
+has not more than a third of the density it has on the sea-level, and
+from which animated existence is for ever excluded.&mdash;<i>Herschel’s Outlines</i>,
+5th edit.</p></blockquote>
+
+<h3>LIGHT OF THE MOON.</h3>
+
+<p>The actual illumination of the lunar surface is not much
+superior to that of weathered sandstone-rock in full sunshine.
+Sir John Herschel has frequently compared the moon setting
+behind the gray perpendicular façade of the Table Mountain
+at the Cape of Good Hope, illuminated by the sun just risen
+from the opposite quarter of the horizon, when it has been
+scarcely distinguishable in brightness from the rock in contact
+with it. The sun and moon being nearly at equal altitudes,
+and the atmosphere perfectly free from cloud or vapour, its
+effect is alike on both luminaries.</p>
+
+<h3>HEAT OF MOONLIGHT.</h3>
+
+<p>M. Zantedeschi has proved, by a long series of experiments
+in the Botanic Gardens at Venice, Florence, and Padua, that,
+contrary to the general opinion, the diffused rays of moonlight
+have an influence upon the organs of plants, as the Sensitive
+Plant and the <i>Desmodium gyrans</i>. The influence was feeble
+compared with that of the sun; but the action is left beyond
+further question.</p>
+
+<p>Melloni has proved that the rays of the Moon give out a<span class="pagenum"><a name="Page_71" id="Page_71">71</a></span>
+slight degree of Heat (see <i>Things not generally Known</i>, p. 7);
+and Professor Piazzi Smyth, from a point of the Peak of Teneriffe
+8840 feet above the sea-level, has found distinctly perceptible
+the heat radiated from the moon, which has been so
+often sought for in vain in a lower region.</p>
+
+<h3>SCENERY OF THE MOON.</h3>
+
+<p>By means of the telescope, mountain-peaks are distinguished
+in the ash-gray light of the larger spots and isolated brightly-shining
+points of the moon, even when the disc is already
+more than half illuminated. Lambert and Schroter have shown
+that the extremely variable intensity of the ash-gray light of
+the moon depends upon the greater or less degree of reflection
+of the sunlight which falls upon the earth, according as it is
+reflected from continuous continental masses, full of sandy deserts,
+grassy steppes, tropical forests, and barren rocky ground,
+or from large ocean surfaces. Lambert made the remarkable
+observation (14th of February 1774) of a change of the ash-coloured
+moonlight into an olive-green colour bordering upon
+yellow. “The moon, which then stood vertically over the
+Atlantic Ocean, received upon its right side the green terrestrial
+light which is reflected towards her when the sky is clear
+by the forest districts of South America.”</p>
+
+<p>Plutarch says distinctly, in his remarkable work <i>On the Face
+in the Moon</i>, that we may suppose the <i>spots</i> to be partly deep
+chasms and valleys, partly mountain-peaks, which cast long
+shadows, like Mount Athos, whose shadow reaches Lemnos.
+The spots cover about two-fifths of the whole disc. In a clear
+atmosphere, and under favourable circumstances in the position
+of the moon, some of the spots are visible to the naked eye;
+as the edge of the Apennines, the dark elevated plain Grimaldus,
+the enclosed <i>Mare Crisium</i>, and Tycho, crowded round with
+numerous mountain ridges and craters.</p>
+
+<p>Professor Alexander remarks, that a map of the eastern
+hemisphere, taken with the Bay of Bengal in the centre, would
+bear a striking resemblance to the face of the moon presented
+to us. The dark portions of the moon he considers to be continental
+elevations, as shown by measuring the average height
+of mountains above the dark and the light portions of the
+moon.</p>
+
+<p>The surface of the moon can be as distinctly seen by a good
+telescope magnifying 1000 times, as it would be if not more
+than 250 miles distant.</p>
+
+<h3>LIFE IN THE MOON.</h3>
+
+<p>A circle of one second in diameter, as seen from the earth,
+on the surface of the moon contains about a square mile.<span class="pagenum"><a name="Page_72" id="Page_72">72</a></span>
+Telescopes, therefore, must be greatly improved before we
+could expect to see signs of inhabitants, as manifested by edifices
+or changes on the surface of the soil. It should, however,
+be observed, that owing to the small density of the materials of
+the moon, and the comparatively feeble gravitation of bodies
+on her surface, muscular force would there go six times as far
+in overcoming the weight of materials as on the earth. Owing
+to the want of air, however, it seems impossible that any form
+of life analogous to those on earth can subsist there. No
+appearance indicating vegetation, or the slightest variation of
+surface which can in our opinion fairly be ascribed to change of
+season, can any where be discerned.&mdash;<i>Sir John Herschel’s Outlines.</i></p>
+
+<h3>THE MOON SEEN THROUGH LORD ROSSE’S TELESCOPE.</h3>
+
+<p>In 1846, the Rev. Dr. Scoresby had the gratification of observing
+the Moon through the stupendous telescope constructed
+by Lord Rosse at Parsonstown. It appeared like a globe of
+molten silver, and every object to the extent of 100 yards was
+quite visible. Edifices, therefore, of the size of York Minster,
+or even of the ruins of Whitby Abbey, might be easily perceived,
+if they had existed. But there was no appearance of
+any thing of that nature; neither was there any indication of
+the existence of water, or of an atmosphere. There were a
+great number of extinct volcanoes, several miles in breadth;
+through one of them there was a line of continuance about 150
+miles in length, which ran in a straight direction, like a railway.
+The general appearance, however, was like one vast ruin
+of nature; and many of the pieces of rock driven out of the
+volcanoes appeared to lie at various distances.</p>
+
+<h3>MOUNTAINS IN THE MOON.</h3>
+
+<p>By the aid of telescopes, we discern irregularities in the surface
+of the moon which can be no other than mountains and
+valleys,&mdash;for this plain reason, that we see the shadows cast
+by the former in the exact proportion as to length which they
+ought to have when we take into account the inclinations of
+the sun’s rays to that part of the moon’s surface on which they
+stand. From micrometrical measurements of the lengths of the
+shadows of the more conspicuous mountains, Messrs. Baer and
+Maedler have given a list of heights for no less than 1095 lunar
+mountains, among which occur all degrees of elevation up to
+22,823 British feet, or about 1400 feet higher than Chimborazo
+in the Andes.</p>
+
+<p>If Chimborazo were as high in proportion to the earth’s
+diameter as a mountain in the moon known by the name of<span class="pagenum"><a name="Page_73" id="Page_73">73</a></span>
+Newton is to the moon’s diameter, its peak would be more
+than sixteen miles high.</p>
+
+<p>Arago calls to mind, that with a 6000-fold magnifying
+power, which nevertheless could not be applied to the moon
+with proportionate results, the mountains upon the moon
+would appear to us just as Mont Blanc does to the naked eye
+when seen from the Lake of Geneva.</p>
+
+<p>We sometimes observe more than half the surface of the
+moon, the eastern and northern edges being more visible at
+one time, and the western or southern at another. By means
+of this libration we are enabled to see the annular mountain
+Malapert (which occasionally conceals the moon’s south pole),
+the arctic landscape round the crater of Gioja, and the large
+gray plane near Endymion, which conceals in superficial extent
+the <i>mare vaporum</i>.</p>
+
+<p>Three-sevenths of the moon are entirely concealed from our
+observation; and must always remain so, unless some new and
+unexpected disturbing causes come into play.&mdash;<i>Humboldt.</i></p>
+
+<blockquote>
+
+<p>The first object to which Galileo directed his telescope was the
+mountainous parts of the moon, when he showed how their summits
+might be measured: he found in the moon some circular districts surrounded
+on all sides by mountains similar to the form of Bohemia.
+The measurements of the mountains were made by the method of the
+tangents of the solar ray. Galileo, as Helvetius did still later, measured
+the distance of the summit of the mountains from the boundary of the
+illuminated portion at the moment when the mountain summit was
+first struck by the solar ray. Humboldt found no observations of the
+lengths of the shadows of the mountains: the summits were “much
+higher than the mountains on our earth.” The comparison is remarkable,
+since, according to Riccioli, very exaggerated ideas of the height
+of our mountains were then entertained. Galileo like all other observers
+up to the close of the eighteenth century, believed in the existence of
+many seas and of a lunar atmosphere.</p></blockquote>
+
+<h3>THE MOON AND THE WEATHER.</h3>
+
+<p>The only influence of the Moon on the Weather of which
+we have any decisive evidence is the tendency to disappearance
+of clouds under the full moon, which Sir John Herschel refers
+to its heat being much more readily absorbed in traversing
+transparent media than direct solar heat, and being extinguished
+in the upper regions of our atmosphere, never reaches the surface
+of the atmosphere at all.</p>
+
+<h3>THE MOON’S ATTRACTION.</h3>
+
+<p>Mr. G. P. Bond of Cambridge, by some investigations to
+ascertain whether the Attraction of the Moon has any effect
+upon the motion of a pendulum, and consequently upon the
+rate of a clock, has found the last to be changed to the amount<span class="pagenum"><a name="Page_74" id="Page_74">74</a></span>
+of 9/1000 of a second daily. At the equator the moon’s attraction
+changes the weight of a body only 1/7000000 of the whole;
+yet this force is sufficient to produce the vast phenomena of
+the tides!</p>
+
+<p>It is no slight evidence of the importance of analysis, that
+Laplace’s perfect theory of tides has enabled us in our astronomical
+ephemerides to predict the height of spring-tides at
+the periods of new and full moon, and thus put the inhabitants
+of the sea on their guard against the increased danger attending
+the lunar revolutions.</p>
+
+<h3>MEASURING THE EARTH BY THE MOON.</h3>
+
+<p>As the form of the Earth exerts a powerful influence on the
+motion of other cosmical bodies, and especially on that of its
+neighbouring satellite, a more perfect knowledge of the motion
+of the latter will enable us reciprocally to draw an inference
+regarding the figure of the earth. Thus, as Laplace ably remarks:
+“an astronomer, without leaving his observatory, may,
+by a comparison of lunar theory with true observations, not
+only be enabled to determine the form and size of the earth,
+but also its distance from the sun and moon; results that otherwise
+could only be arrived at by long and arduous expeditions
+to the most remote parts of both hemispheres.” The compression
+which may be inferred from lunar inequalities affords an
+advantage not yielded by individual measurements of degrees
+or experiments with the pendulum, since it gives a mean
+amount which is referable to the whole planet.&mdash;<i>Humboldt’s
+Cosmos</i>, vol. i.</p>
+
+<p>The distance of the moon from the earth is about 240,000
+miles; and if a railway-carriage were to travel at the rate of
+1000 miles a-day, it would be eight months in reaching the
+moon. But that is nothing compared with the length of time
+it would occupy a locomotive to reach the sun from the earth:
+if travelling at the rate of 1000 miles a-day, it would require
+260 years to reach it.</p>
+
+<h3>CAUSE OF ECLIPSES.</h3>
+
+<p>As the Moon is at a very moderate distance from us (astronomically
+speaking), and is in fact our nearest neighbour, while
+the sun and stars are in comparison immensely beyond it, it
+must of necessity happen that at one time or other it must
+<i>pass over</i>, and <i>occult</i> or <i>eclipse</i>, every star or planet within its
+zone, and, as seen from the <i>surface</i> of the earth, even somewhat
+beyond it. Nor is the sun itself exempt from being thus
+hidden whenever any part of the moon’s disc, in this her tortuous
+course, comes to <i>overlap</i> any part of the space occupied<span class="pagenum"><a name="Page_75" id="Page_75">75</a></span>
+in the heavens by that luminary. On these occasions is exhibited
+the most striking and impressive of all the occasional
+phenomena of astronomy, an <i>Eclipse of the Sun</i>, in which a
+greater or less portion, or even in some conjunctures the whole
+of its disc, is obscured, and, as it were, obliterated, by the superposition
+of that of the moon, which appears upon it as a
+circularly-terminated black spot, producing a temporary diminution
+of daylight, or even nocturnal darkness, so that the
+stars appear as if at midnight.&mdash;<i>Sir John Herschel’s Outlines.</i></p>
+
+<h3>VAST NUMBERS IN THE UNIVERSE.</h3>
+
+<p>The number of telescopic stars in the Milky Way uninterrupted
+by any nebulæ is estimated at 18,000,000. To compare
+this number with something analogous, Humboldt calls
+attention to the fact, that there are not in the whole heavens
+more than about 8000 stars, between the first and the sixth
+magnitudes, visible to the naked eye. The barren astonishment
+excited by numbers and dimensions in space when not
+considered with reference to applications engaging the mental
+and perceptive powers of man, is awakened in both extremes
+of the universe&mdash;in the celestial bodies as in the minutest
+animalcules. A cubic inch of the polishing slate of Bilin contains,
+according to Ehrenberg, 40,000 millions of the siliceous
+shells of Galionellæ.</p>
+
+<h3>FOR WHAT PURPOSE WERE THE STARS CREATED?</h3>
+
+<p>Surely not (says Sir John Herschel) to illuminate <i>our</i> nights,
+which an additional moon of the thousandth part of the size of
+our own would do much better; nor to sparkle as a pageant
+void of meaning and reality, and bewilder us among vain conjectures.
+Useful, it is true, they are to man as points of exact
+and permanent reference; but he must have studied astronomy
+to little purpose, who can suppose man to be the only object of
+his Creator’s care, or who does not see in the vast and wonderful
+apparatus around us provision for other races of animated
+beings. The planets derive their light from the sun; but that
+cannot be the case with the stars. These doubtless, then, are
+themselves suns; and may perhaps, each in its sphere, be the
+presiding centre round which other planets, or bodies of which
+we can form no conception from any analogy offered by our
+own system, are circulating.<a name="FNanchor_19" id="FNanchor_19" href="#Footnote_19" class="fnanchor">19</a></p>
+
+<h3>NUMBER OF STARS.</h3>
+
+<p>Various estimates have been hazarded on the Number of
+Stars throughout the whole heavens visible to us by the aid of<span class="pagenum"><a name="Page_76" id="Page_76">76</a></span>
+our colossal telescopes. Struve assumes for Herschel’s 20-feet
+reflector, that a magnifying power of 180 would give 5,800,000
+for the number of stars lying within the zones extending 30°
+on either side of the equator, and 20,374,000 for the whole
+heavens. Sir William Herschel conjectured that 18,000,000 of
+stars in the Milky Way might be seen by his still more powerful
+40-feet reflecting telescope.&mdash;<i>Humboldt’s Cosmos</i>, vol. iii.</p>
+
+<p>The assumption that the extent of the starry firmament is
+literally infinite has been made by Dr. Olbers the basis of a
+conclusion that the celestial spaces are in some slight degree
+deficient in <i>transparency</i>; so that all beyond a certain distance
+is and must remain for ever unseen, the geometrical progression
+of the extinction of light far outrunning the effect of any
+conceivable increase in the power of our telescopes. Were it
+not so, it is argued that every part of the celestial concave
+ought to shine with the brightness of the solar disc, since no
+visual ray could be so directed as not, in some point or other of
+its infinite length, to encounter such a disc.&mdash;<i>Edinburgh Review</i>,
+Jan. 1848.</p>
+
+<h3>STARS THAT HAVE DISAPPEARED.</h3>
+
+<p>Notwithstanding the great accuracy of the catalogued positions
+of telescopic fixed stars and of modern star-maps, the
+certainty of conviction that a star in the heavens has actually
+disappeared since a certain epoch can only be arrived at
+with great caution. Errors of actual observation, of reduction,
+and of the press, often disfigure the very best catalogues. The
+disappearance of a heavenly body from the place in which it
+had been before distinctly seen, may be the result of its own
+motion as much as of any such diminution of its photometric
+process as would render the waves of light too weak to excite
+our organs of sight. What we no longer see, is not necessarily
+annihilated. The idea of destruction or combustion, as applied
+to disappearing stars, belongs to the age of Tycho Brahe.
+Even Pliny makes it a question. The apparent eternal cosmical
+alternation of existence and destruction is not annihilation;
+it is merely the transition of matter into new forms, into combinations
+which are subject to new processes. Dark cosmical
+bodies may by a renewed process of light again become luminous.&mdash;<i>Humboldt’s
+Cosmos</i>, vol. iii.</p>
+
+<h3>THE POLE-STAR FOUR THOUSAND YEARS AGO.</h3>
+
+<p>Sir John Herschel, in his <i>Outlines of Astronomy</i>, thus shows
+the changes in the celestial pole in 4000 years:</p>
+
+<blockquote>
+
+<p>At the date of the erection of the Pyramid of Gizeh, which precedes
+the present epoch by nearly 4000 years, the longitudes of all the stars<span class="pagenum"><a name="Page_77" id="Page_77">77</a></span>
+were less by 55° 45′ than at present. Calculating from this datum
+the place of the pole of the heavens among the stars, it will be found
+to fall near α Draconis; its distance from that star being 3° 44′ 25″.
+This being the most conspicuous star in the immediate neighbourhood,
+was therefore the Pole Star of that epoch. The latitude of Gizeh being
+just 30° north, and consequently the altitude of the North Pole there
+also 30°, it follows that the star in question must have had at its
+lowest culmination at Gizeh an altitude of 25° 15′ 35″. Now it is a
+remarkable fact, that of the nine pyramids still existing at Gizeh, six
+(including all the largest) have the narrow passages by which alone they
+can be entered (all which open out on the northern faces of their respective
+pyramids) inclined to the horizon downwards at angles the
+mean of which is 26° 47′. At the bottom of every one of these passages,
+therefore, the Pole Star must have been visible at its lower culmination;
+a circumstance which can hardly be supposed to have been unintentional,
+and was doubtless connected (perhaps superstitiously) with the
+astronomical observations of that star, of whose proximity to the pole
+at the epoch of the erection of these wonderful structures we are thus
+furnished with a monumental record of the most imperishable nature.</p></blockquote>
+
+<h3>THE PLEIADES.</h3>
+
+<p>The Pleiades prove that, several thousand years ago even
+as now, stars of the seventh magnitude were invisible to the
+naked eye of average visual power. The group consists of
+seven stars, of which six only, of the third, fourth, and fifth
+magnitudes, could be readily distinguished. Of these Ovid
+says (<i>Fast.</i> iv. 170):</p>
+
+<div class="poem-container">
+<div class="poem"><div class="stanza">
+<span class="iq">“Quæ septem dici, sex tamen esse solent.”<br /></span>
+</div></div>
+</div>
+
+<p class="in0">Aratus states there were only six stars visible in the Pleiades.</p>
+
+<p>One of the daughters of Atlas, Merope, the only one who
+was wedded to a mortal, was said to have veiled herself for
+very shame and to have disappeared. This is probably the
+star of the seventh magnitude, which we call Celæne; for Hipparchus,
+in his commentary on Aratus, observes that on clear
+moonless nights <i>seven stars</i> may actually be seen.</p>
+
+<p>The Pleiades were doubtless known to the rudest nations
+from the earliest times; they are also called the <i>mariner’s stars</i>.
+The name is from πλεῖν (<i>plein</i>), ‘to sail.’ The navigation of
+the Mediterranean lasted from May to the beginning of November,
+from the early rising to the early setting of the Pleiades.
+In how many beautiful effusions of poetry and sentiment has
+“the Lost Pleiad” been deplored!&mdash;and, to descend to more familiar
+illustration of this group, the “Seven Stars,” the sailors’
+favourites, and a frequent river-side public-house sign, may be
+traced to the Pleiades.</p>
+
+<h3>CHANGE OF COLOUR IN THE STARS.</h3>
+
+<p>The scintillation or twinkling of the stars is accompanied
+by variations of colour, which have been remarked from a very
+early age. M. Arago states, upon the authority of M. Babinet,<span class="pagenum"><a name="Page_78" id="Page_78">78</a></span>
+that the name of Barakesch, given by the Arabians to Sirius,
+signifies <i>the star of a thousand colours</i>; and Tycho Brahe, Kepler,
+and others, attest to similar change of colour in twinkling.
+Even soon after the invention of the telescope, Simon Marius
+remarked that by removing the eye-piece of the telescope the
+images of the stars exhibited rapid fluctuations of brightness
+and colour. In 1814 Nicholson applied to the telescope
+a smart vibration, which caused the image of the star to be
+transformed into a curved line of light returning into itself,
+and diversified by several colours; each colour occupied about
+a third of the whole length of the curve, and by applying ten
+vibrations in a second, the light of Sirius in that time passed
+through thirty changes of colour. Hence the stars in general
+shine only by a portion of their light, the effect of twinkling
+being to diminish their brightness. This phenomenon M. Arago
+explains by the principle of the interference of light.</p>
+
+<p>Ptolemy is said to have noted Sirius as a <i>red</i> star, though
+it is now white. Sirius twinkles with red and blue light, and
+Ptolemy’s eyes, like those of several other persons, may have
+been more sensitive to the <i>red</i> than to the <i>blue</i> rays.&mdash;<i>Sir David
+Brewster’s More Worlds than One</i>, p. 235.</p>
+
+<p>Some of the double stars are of very different and dissimilar
+colours; and to the revolving planetary bodies which apparently
+circulate around them, a day lightened by a red light is succeeded
+by, not a night, but a day equally brilliant, though illuminated
+only by a green light.</p>
+
+<h3>DISTANCE OF THE NEAREST FIXED STAR FROM THE EARTH.</h3>
+
+<p>Sir John Herschel wrote in 1833: “What is the distance
+of the nearest fixed star? What is the scale on which our
+visible firmament is constructed? And what proportion do its
+dimensions bear to those of our own immediate system? To this,
+however, astronomy has hitherto proved unable to supply an
+answer. All we know on this subject is negative.” To these
+questions, however, an answer can now be given. Slight
+changes of position of some of the stars, called parallax, have
+been distinctly observed and measured; and among these stars
+No. 61 Cygni of Flamstead’s catalogue has a parallax of 5″, and
+that of α Centauri has a proper motion of 4″ per annum.</p>
+
+<p>The same astronomer states that each second of parallax indicates
+a distance of 20 billions of miles, or 3¼ years’ journey of
+light. Now the light sent to us by the sun, as compared with
+that sent by Sirius and α Centauri, is about 22 thousand millions
+to 1. “Hence, from the parallax assigned above to that
+star, it is easy to conclude that its intrinsic splendour, as compared
+with that of our sun at equal distances, is 2·3247, that
+of the sun being unity. The light of Sirius is four times that<span class="pagenum"><a name="Page_79" id="Page_79">79</a></span>
+of α Centauri, and its parallax only 0·15″. This, in effect, ascribes
+to it an intrinsic splendour equal to 96·63 times that of
+α Centauri, and therefore 224·7 times that of our sun.”</p>
+
+<p>This is justly regarded as one of the most brilliant triumphs
+of astronomical science, for the delicacy of the investigation is
+almost inconceivable; yet the reasoning is as unimpeachable
+as the demonstration of a theorem of Euclid.</p>
+
+<h3>LIGHT OF A STAR SIXTEENFOLD THAT OF THE SUN.</h3>
+
+<p>The bright star in the constellation of the Lyre, termed
+Vega, is the brightest in the northern hemisphere; and the combined
+researches of Struve, father and son, have found that
+the distance of this star from the earth is no less than 130 billions
+of miles! Light travelling at the rate of 192 thousand
+miles in a second consequently occupies twenty-one years in
+passing from this star to the earth. Now it has been found,
+by comparing the light of Vega with the light of the sun, that
+if the latter were removed to the distance of 130 billions of
+miles, his apparent brightness would not amount to more than
+the sixteenth part of the apparent brightness of Vega. We
+are therefore warranted in concluding that the light of Vega
+is equal to that of sixteen suns.</p>
+
+<h3>DIVERSITIES OF THE PLANETS.</h3>
+
+<p>In illustration of the great diversity of the physical peculiarities
+and probable condition of the planets, Sir John Herschel
+describes the intensity of solar radiation as nearly seven times
+greater on Mercury than on the earth, and on Uranus 330 times
+less; the proportion between the two extremes being that of
+upwards of 2000 to 1. Let any one figure to himself, (adds
+Sir John,) the condition of our globe were the sun to be septupled,
+to say nothing of the greater ratio; or were it diminished
+to a seventh, or to a 300th of its actual power!
+Again, the intensity of gravity, or its efficacy in counteracting
+muscular power and repressing animal activity, on Jupiter
+is nearly two-and-a-half times that on the earth; on
+Mars not more than one-half; on the moon one-sixth; and on
+the smaller planets probably not more than one-twentieth;
+giving a scale of which the extremes are in the proportion of
+sixty to one. Lastly, the density of Saturn hardly exceeds one-eighth
+of the mean density of the earth, so that it must consist
+of materials not much heavier than cork.</p>
+
+<blockquote>
+
+<p>Jupiter is eleven times, Saturn ten times, Uranus five times, and
+Neptune nearly six times, the diameter of our earth.</p>
+
+<p>These four bodies revolve in space at such distances from the sun,
+that if it were possible to start thence for each in succession, and to travel
+at the railway speed of 33 miles per hour, the traveller would reach</p>
+
+<p><span class="pagenum"><a name="Page_80" id="Page_80">80</a></span></p>
+
+<table summary="Time to travel by train to some planets">
+  <tr>
+    <td class="tdl">Jupiter in</td>
+    <td class="tdr">1712</td>
+    <td class="tdc lrpad">years</td></tr>
+  <tr>
+    <td class="tdl">Saturn</td>
+    <td class="tdr">3113</td>
+    <td class="tdc">”</td></tr>
+  <tr>
+    <td class="tdl">Uranus</td>
+    <td class="tdr">6226</td>
+    <td class="tdc">”</td></tr>
+  <tr>
+    <td class="tdl">Neptune</td>
+    <td class="tdr">9685</td>
+    <td class="tdc">”</td></tr>
+</table>
+
+<p class="in0">If, therefore, a person had commenced his journey at the period of the
+Christian era, he would now have to travel nearly 1300 years before he
+would arrive at the planet Saturn; more than 4300 years before he
+would reach Uranus; and no less than 7800 years before he could reach
+the orbit of Neptune.</p>
+
+<p>Yet the light which comes to us from these remote confines of the
+solar system first issued from the sun, and is then reflected from the
+surface of the planet. When the telescope is turned towards Neptune,
+the observer’s eye sees the object by means of light that issued from
+the sun eight hours before, and which since then has passed nearly
+twice through that vast space which railway speed would require almost
+a century of centuries to accomplish.&mdash;<i>Bouvier’s Familiar Astronomy.</i></p></blockquote>
+
+<h3>GRAND RESULTS OF THE DISCOVERY OF JUPITER’S
+SATELLITES.</h3>
+
+<p>This discovery, one of the first fruits of the invention of the
+telescope, and of Galileo’s early and happy idea of directing its
+newly-found powers to the examination of the heavens, forms
+one of the most memorable epochs in the history of astronomy.
+The first astronomical solution of the great problem of <i>the
+longitude</i>, practically the most important for the interests of
+mankind which has ever been brought under the dominion of
+strict scientific principles, dates immediately from this discovery.
+The final and conclusive establishment of the Copernican
+system of astronomy may also be considered as referable
+to the discovery and study of this exquisite miniature system,
+in which the laws of the planetary motions, as ascertained by
+Kepler, and specially that which connects their periods and
+distances, were specially traced, and found to be satisfactorily
+maintained. And (as if to accumulate historical interest on
+this point) it is to the observation of the eclipses of Jupiter’s
+satellites that we owe the grand discovery of the aberration of
+light, and the consequent determination of the enormous velocity
+of that wonderful element&mdash;192,000 miles per second. Mr.
+Dawes, in 1849, first noticed the existence of round, well-defined,
+bright spots on the belts of Jupiter. They vary in situation
+and number, as many as ten having been seen on one
+occasion. As the belts of Jupiter have been ascribed to the
+existence of currents analogous to our trade-winds, causing the
+body of Jupiter to be visible through his cloudy atmosphere, Sir
+John Herschel conjectures that those bright spots may possibly
+be insulated masses of clouds of local origin, similar to the
+cumuli which sometimes cap ascending columns of vapour in
+our atmosphere.</p>
+
+<p>It would require nearly 1300 globes of the size of our earth<span class="pagenum"><a name="Page_81" id="Page_81">81</a></span>
+to make one of the bulk of Jupiter. A railway-engine travelling
+at the rate of thirty-three miles an hour would travel
+round the earth in a month, but would require more than
+eleven months to perform a journey round Jupiter.</p>
+
+<h3>WAS SATURN’S RING KNOWN TO THE ANCIENTS?</h3>
+
+<p>In Maurice’s <i>Indian Antiquities</i> is an engraving of Sani,
+the Saturn of the Hindoos, taken from an image in a very ancient
+pagoda, which represents the deity encompassed by a <i>ring</i>
+formed of two serpents. Hence it is inferred that the ancients
+were acquainted with the existence of the ring of Saturn.</p>
+
+<p>Arago mentions the remarkable fact of the ring and fourth
+satellite of Saturn having been seen by Sir W. Herschel with
+his smaller telescope by the naked eye, without any eye-piece.</p>
+
+<p>The first or innermost of Saturn’s satellites is nearer to the
+central body than any other of the secondary planets. Its distance
+from the centre of Saturn is 80,088 miles; from the surface
+of the planet 47,480 miles; and from the outmost edge of
+the ring only 4916 miles. The traveller may form to himself
+an estimate of the smallness of this amount by remembering
+the statement of the well-known navigator, Captain Beechey,
+that he had in three years passed over 72,800 miles.</p>
+
+<p>According to very recent observations, Saturn’s ring is divided
+into <i>three</i> separate rings, which, from the calculations
+of Mr. Bond, an American astronomer, must be fluid. He is
+of opinion that the number of rings is continually changing,
+and that their maximum number, in the normal condition of
+the mass, does not exceed <i>twenty</i>. Mr. Bond likewise maintains
+that the power which sustains the centre of gravity of the <i>ring</i>
+is not in the planet itself, but in its satellites; and the satellites,
+though constantly disturbing the ring, actually sustain it in the
+very act of perturbation. M. Otto Struve and Mr. Bond have
+lately studied with the great Munich telescope, at the observatory
+of Pulkowa, the <i>third</i> ring of Saturn, which Mr. Lassell and
+Mr. Bond discovered to be <i>fluid</i>. They saw distinctly the dark
+interval between this fluid ring and the two old ones, and even
+measured its dimensions; and they perceived at its inner margin
+an edge feebly illuminated, which they thought might be
+the commencement of a fourth ring. These astronomers are of
+opinion, that the fluid ring is not of very recent formation, and
+that it is not subject to rapid change; and they have come to
+the extraordinary conclusion, that the inner border of the ring
+has, since the time of Huygens, been gradually approaching to
+the body of Saturn, and that <i>we may expect, sooner or later,
+perhaps in some dozen of years, to see the rings united with the
+body of the planet</i>. But this theory is by other observers pronounced
+untenable.</p>
+
+<p><span class="pagenum"><a name="Page_82" id="Page_82">82</a></span></p>
+
+<h3>TEMPERATURE OF THE PLANET MERCURY.</h3>
+
+<p>Mercury being so much nearer to the Sun than the Earth,
+he receives, it is supposed, seven times more heat than the
+earth. Mrs. Somerville says: “On Mercury, the mean heat
+arising from the intensity of the sun’s rays must be above that
+of boiling quicksilver, and water would boil even at the poles.”
+But he may be provided with an atmosphere so constituted as
+to absorb or reflect a great portion of the superabundant heat;
+so that his inhabitants (if he have any) may enjoy a climate as
+temperate as any on our globe.</p>
+
+<h3>SPECULATIONS ON VESTA AND PALLAS.</h3>
+
+<p>The most remarkable peculiarities of these ultra-zodiacal
+planets, according to Sir John Herschel, must lie in this condition
+of their state: a man placed on one of them would spring
+with ease sixty feet high, and sustain no greater shock in his
+descent than he does on the earth from leaping a yard. On
+such planets, giants might exist; and those enormous animals
+which on the earth require the buoyant power of water to counteract
+their weight, might there be denizens of the land. But
+of such speculations there is no end.</p>
+
+<h3>IS THE PLANET MARS INHABITED?</h3>
+
+<p>The opponents of the doctrine of the Plurality of Worlds
+allow that a greater probability exists of Mars being inhabited
+than in the case of any other planet. His diameter is 4100
+miles; and his surface exhibits spots of different hues,&mdash;the
+<i>seas</i>, according to Sir John Herschel, being <i>green</i>, and the land
+<i>red</i>. “The variety in the spots,” says this astronomer, “may
+arise from the planet not being destitute of atmosphere and
+cloud; and what adds greatly to the probability of this, is the
+appearance of brilliant white spots at its poles, which have
+been conjectured, with some probability, to be snow, as they
+disappear when they have been long exposed to the sun, and are
+greatest when emerging from the long night of their polar
+winter, the snow-line then extending to about six degrees from
+the pole.” “The length of the day,” says Sir David Brewster,
+“is almost exactly twenty-four hours,&mdash;the same as that
+of the earth. Continents and oceans and green savannahs
+have been observed upon Mars, and the snow of his polar regions
+has been seen to disappear with the heat of summer.”
+We actually see the clouds floating in the atmosphere of Mars,
+and there is the appearance of land and water on his disc.
+In a sketch of this planet, as seen in the pure atmosphere of
+Calcutta by Mr. Grant, it appears, to use his words, “actually<span class="pagenum"><a name="Page_83" id="Page_83">83</a></span>
+as a little world,” and as the earth would appear at a distance,
+with its seas and continents of different shades. As the diameter
+of Mars is only about one half that of our earth, the
+weight of bodies will be about one half what it would be if they
+were placed upon our globe.</p>
+
+<h3>DISCOVERY OF THE PLANET NEPTUNE.</h3>
+
+<p>This noble discovery marked in a signal manner the maturity
+of astronomical science. The proof, or at least the urgent
+presumption, of the existence of such a planet, as a means
+of accounting (by its attraction) for certain small irregularities
+observed in the motions of Uranus, was afforded almost simultaneously
+by the independent researches of two geometers,
+Mr. Adams of Cambridge, and M. Leverrier of Paris, who were
+enabled <i>from theory alone</i> to calculate whereabouts it ought
+to appear in the heavens, <i>if visible</i>, the places thus independently
+calculated agreeing surprisingly. <i>Within a single degree</i>
+of the place assigned by M. Leverrier’s calculations, and
+by him communicated to Dr. Galle of the Royal Observatory
+at Berlin, it was actually found by that astronomer on the very
+first night after the receipt of that communication, on turning
+a telescope on the spot, and comparing the stars in its immediate
+neighbourhood with those previously laid down in one of
+the zodiacal charts. This remarkable verification of an indication
+so extraordinary took place on the 23d of September 1846.<a name="FNanchor_20" id="FNanchor_20" href="#Footnote_20" class="fnanchor">20</a>&mdash;<i>Sir
+John Herschel’s Outlines.</i></p>
+
+<p>Neptune revolves round the sun in about 172 years, at a
+mean distance of thirty,&mdash;that of Uranus being nineteen, and
+that of the earth one: and by its discovery the solar system
+has been extended <i>one thousand millions of miles</i> beyond its
+former limit.</p>
+
+<p>Neptune is suspected to have a ring, but the suspicion has
+not been confirmed. It has been demonstrated by the observations
+of Mr. Lassell, M. Otto Struve, and Mr. Bond, to be
+attended by at least one satellite.</p>
+
+<p>One of the most curious facts brought to light by the discovery
+of Neptune, is the failure of Bode’s law to give an approximation
+to its distance from the sun; a striking exemplification
+of the danger of trusting to the universal applicability
+of an empirical law. After standing the severe test which led<span class="pagenum"><a name="Page_84" id="Page_84">84</a></span>
+to the discovery of the asteroids, it seemed almost contrary to
+the laws of probability that the discovery of another member
+of the planetary system should prove its failure as an universal
+rule.</p>
+
+<h3>MAGNITUDE OF COMETS.</h3>
+
+<p>Although Comets have a smaller mass than any other cosmical
+bodies&mdash;being, according to our present knowledge, probably
+not equal to 1/5000th part of the earth’s mass&mdash;yet they
+occupy the largest space, as their tails in several instances extend
+over many millions of miles. The cone of luminous vapour
+which radiates from them has been found in some cases
+(as in 1680 and 1811) equal to the length of the earth’s distance
+from the sun, forming a line that intersects both the orbits of
+Venus and Mercury. It is even probable that the vapour of
+the tails of comets mingled with our atmosphere in the years
+1819 and 1823.&mdash;<i>Humboldt’s Cosmos</i>, vol. i.</p>
+
+<h3>COMETS VISIBLE IN SUNSHINE&mdash;THE GREAT COMET OF 1843.</h3>
+
+<p>The phenomenon of the tail of a Comet being visible in
+bright Sunshine, which is recorded of the comet of 1402, occurred
+again in the case of the large comet of 1843, whose
+nucleus and tail were seen in North America on February 28th
+(according to the testimony of J.&nbsp;G. Clarke, of Portland, State
+of Maine), between one and three o’clock in the afternoon.
+The distance of the very dense nucleus from the sun’s light
+admitted of being measured with much exactness. The nucleus
+and tail (a darker space intervening) appeared like a very
+pure white cloud.&mdash;<i>American Journal of Science</i>, vol. xiv.</p>
+
+<p>E. C. Otté, the translator of Bohn’s edition of Humboldt’s
+<i>Cosmos</i>, at New Bedford, Massachusetts, U.S., Feb. 28th, 1843,
+distinctly saw the above comet between one and two in the
+afternoon. The sky at the time was intensely blue, and the
+sun shining with a dazzling brightness unknown in European
+climates.</p>
+
+<p>This very remarkable Comet, seen in England on the 17th
+of March 1843, had a nucleus with the appearance of a planetary
+disc, and the brightness of a star of the first or second magnitude.
+It had a double tail divided by a dark line. At the
+Cape of Good Hope it was seen in full daylight, and in the immediate
+vicinity of the sea; but the most remarkable fact in
+its history was its near approach to the sun, its distance from
+his surface being only <i>one-fourteenth</i> of his diameter. The heat
+to which it was exposed, therefore, was much greater than that
+which Sir Isaac Newton ascribed to the comet of 1680, namely
+200 times that of red-hot iron. Sir John Herschel has computed
+that it must have been 24 times greater than that which<span class="pagenum"><a name="Page_85" id="Page_85">85</a></span>
+was produced in the focus of Parker’s burning lens, 32 inches
+in diameter, which melts crystals of quartz and agate.<a name="FNanchor_21" id="FNanchor_21" href="#Footnote_21" class="fnanchor">21</a></p>
+
+<h3>THE MILKY WAY UNFATHOMABLE.</h3>
+
+<p>M. Struve of Pulkowa has compared Sir William Herschel’s
+opinion on this subject, as maintained in 1785, with that to
+which he was subsequently led; and arrives at the conclusion
+that, according to Sir W. Herschel himself, the visible extent
+of the Milky Way increases with the penetrating power of the
+telescopes employed; that it is impossible to discover by his
+instruments the termination of the Milky Way (as an independent
+cluster of stars); and that even his gigantic telescope
+of forty feet focal length does not enable him to extend our
+knowledge of the Milky Way, which is incapable of being
+sounded. Sir William Herschel’s <i>Theory of the Milky Way</i> was
+as follows: He considered our solar system, and all the stars
+which we can see with the eye, as placed within, and constituting
+a part of, the nebula of the Milky Way, a congeries of
+many millions of stars, so that the projection of these stars
+must form a luminous track on the concavity of the sky; and
+by estimating or counting the number of stars in different directions,
+he was able to form a rude judgment of the probable
+form of the nebula, and of the probable position of the solar
+system within it.</p>
+
+<p>This remarkable belt has maintained from the earliest ages
+the same relative situation among the stars; and, when examined
+through powerful telescopes, is found (wonderful to
+relate!) <i>to consist entirely of stars scattered by millions</i>, like
+glittering dust, on the black ground of the general heavens.</p>
+
+<h3>DISTANCES OF NEBULÆ.</h3>
+
+<p>These are truly astounding. Sir William Herschel estimated
+the distance of the annular nebula between Beta and
+Gamma Lyræ to be from our system 950 times that of Sirius;
+and a globular cluster about 5½° south-east of Beta Sir William
+computed to be one thousand three hundred billions of miles
+from our system. Again, in Scutum Sobieski is one nebula in
+the shape of a horseshoe; but which, when viewed with high
+magnifying power, presents a different appearance. Sir William
+Herschel estimated this nebula to be 900 times farther from us
+than Sirius. In some parts of its vicinity he observed 588
+stars in his telescope at one time; and he counted 258,000 in
+a space 10° long and 2½° wide. There is a globular cluster
+between the mouths of Pegasus and Equuleus, which Sir William<span class="pagenum"><a name="Page_86" id="Page_86">86</a></span>
+Herschel estimated to be 243 times farther from us than
+Sirius. Caroline Herschel discovered in the right foot of Andromeda
+a nebula of enormous dimensions, placed at an inconceivable
+distance from us: it consists probably of myriads of
+solar systems, which, taken together, are but a point in the
+universe. The nebula about 10° west of the principal star in
+Triangulum is supposed by Sir William Herschel to be 344
+times the distance of Sirius from the earth, which would be the
+immense sum of nearly seventeen thousand billions of miles
+from our planet.</p>
+
+<h3>INFINITE SPACE.</h3>
+
+<p>After the straining mind has exhausted all its resources in
+attempting to fathom the distance of the smallest telescopic
+star, or the faintest nebula, it has reached only the visible confines
+of the sidereal creation. The universe of stars is but an
+atom in the universe of space; above it, and beneath it, and
+around it, there is still infinity.</p>
+
+<h3 title="Origin of Our Planetary System.">ORIGIN OF OUR PLANETARY SYSTEM. THE NEBULAR
+HYPOTHESIS.<a name="FNanchor_22" id="FNanchor_22" href="#Footnote_22" class="fnanchor smaller">22</a></h3>
+
+<p>The commencement of our Planetary System, including the
+sun, must, according to Kant and Laplace, be regarded as an
+immense nebulous mass filling the portion of space which is
+now occupied by our system far beyond the limits of Neptune,
+our most distant planet. Even now we perhaps see similar
+masses in the distant regions of the firmament, as patches of
+nebulæ, and nebulous stars; within our system also, comets,
+the zodiacal light, the corona of the sun during a total eclipse,
+exhibit resemblances of a nebulous substance, which is so thin
+that the light of the stars passes through it unenfeebled and
+unrefracted. If we calculate the density of the mass of our
+planetary system, according to the above assumption, for the
+time when it was a nebulous sphere which reached to the path
+of the outmost planet, we should find that it would require
+several cubic miles of such matter to weigh a single grain.&mdash;<i>Professor
+Helmholtz.</i></p>
+
+<p>A quarter of a century ago, Sir John Herschel expressed his
+opinion that those nebulæ which were not resolved into individual
+stars by the highest powers then used, might be hereafter
+completely resolved by a further increase of optical power:</p>
+
+<p><span class="pagenum"><a name="Page_87" id="Page_87">87</a></span></p>
+
+<blockquote>
+
+<p>In fact, this probability has almost been converted into a certainty
+by the magnificent reflecting telescope constructed by Lord Rosse, of
+6 feet in aperture, which has resolved, or rendered resolvable, multitudes
+of nebulæ which had resisted all inferior powers. The sublimity of the
+spectacle afforded by that instrument of some of the larger globular and
+other clusters is declared by all who have witnessed it to be such as no
+words can express.<a name="FNanchor_23" id="FNanchor_23" href="#Footnote_23" class="fnanchor">23</a></p>
+
+<p>Although, therefore, nebulæ do exist, which even in this powerful
+telescope appear as nebulæ, without any sign of resolution, it may very
+reasonably be doubted whether there be really any essential physical
+distinction between nebulæ and clusters of stars, at least in the nature of
+the matter of which they consist; and whether the distinction between
+such nebulæ as are easily resolved, barely resolvable with excellent telescopes,
+and altogether irresolvable with the best, be any thing else than
+one of degree, arising merely from the excessive minuteness and multitude
+of the stars of which the latter, as compared with the former, consist.&mdash;<i>Outlines
+of Astronomy</i>, 5th edit. 1858.</p></blockquote>
+
+<p>It should be added, that Sir John Herschel considers the
+“nebular hypothesis” and the above theory of sidereal aggregation
+to stand quite independent of each other.</p>
+
+<h3>ORIGIN OF HEAT IN OUR SYSTEM.</h3>
+
+<p>Professor Helmholtz, assuming that at the commencement
+the density of the nebulous matter was a vanishing quantity,
+as compared with the present density of the sun and planets,
+calculates how much work has been performed by the condensation;
+how much of this work still exists in the form of mechanical
+force, as attraction of the planets towards the sun, and
+as <i>vis viva</i> of their motion; and finds by this how much of the
+force has been converted into heat.</p>
+
+<blockquote>
+
+<p>The result of this calculation is, that only about the 45th part of
+the original mechanical force remains as such, and that the remainder,
+converted into heat, would be sufficient to raise a mass of water equal to
+the sun and planets taken together, not less than 28,000,000 of degrees
+of the centigrade scale. For the sake of comparison, Professor Helmholtz
+mentions that the highest temperature which we can produce by
+the oxy-hydrogen blowpipe, which is sufficient to vaporise even platina,
+and which but few bodies can endure, is estimated at about 2000 degrees.
+Of the action of a temperature of 28,000,000 of such degrees we can
+form no notion. If the mass of our entire system were of pure coal,
+by the combustion of the whole of it only the 350th part of the above
+quantity would be generated.</p>
+
+<p>The store of force at present possessed by our system is equivalent
+to immense quantities of heat. If our earth were by a sudden shock
+brought to rest in her orbit&mdash;which is not to be feared in the existing
+arrangement of our system&mdash;by such a shock a quantity of heat would
+be generated equal to that produced by the combustion of fourteen such
+earths of solid coal. Making the most unfavourable assumption as to
+its capacity for heat, that is, placing it equal to that of water, the mass<span class="pagenum"><a name="Page_88" id="Page_88">88</a></span>
+of the earth would thereby be heated 11,200°; it would therefore be quite
+fused, and for the most part reduced to vapour. If, then, the earth,
+after having been thus brought to rest, should fall into the sun, which
+of course would be the case, the quantity of heat developed by the shock
+would be 400 times greater.</p></blockquote>
+
+<h3>AN ASTRONOMER’S DREAM VERIFIED.</h3>
+
+<p>The most fertile region in astronomical discovery during
+the last quarter of a century has been the planetary members
+of the solar system. In 1833, Sir John Herschel enumerated ten
+planets as visible from the earth, either by the unaided eye or
+by the telescope; the number is now increased more than fivefold.
+With the exception of Neptune, the discovery of new
+planets is confined to the class called Asteroids. These all
+revolve in elliptic orbits between those of Jupiter and Mars.
+Zitius of Wittemberg discovered an empirical law, which
+seemed to govern the distances of the planets from the sun;
+but there was a remarkable interruption in the law, according
+to which a planet ought to have been placed between Mars and
+Jupiter. Professor Bode of Berlin directed the attention of
+astronomers to the possibility of such a planet existing; and
+in seven years’ observations from the commencement of the
+present century, not one but four planets were found, differing
+widely from one another in the elements of their orbits, but
+agreeing very nearly at their mean distances from the sun with
+that of the supposed planet. This curious coincidence of the
+mean distances of these four asteroids with the planet according
+to Bode’s law, as it is generally called, led to the conjecture
+that these four planets were but fragments of the missing
+planet, blown to atoms by some internal explosion, and that
+many more fragments might exist, and be possibly discovered
+by diligent search.</p>
+
+<p>Concerning this apparently wild hypothesis, Sir John Herschel
+offered the following remarkable apology: “This may
+serve as a specimen of the dreams in which astronomers, like
+other speculators, occasionally and harmlessly indulge.”</p>
+
+<p>The dream, wild as it appeared, has been realised now. Sir
+John, in the fifth edition of his <i>Outlines of Astronomy</i>, published
+in 1858, tells us:</p>
+
+<blockquote>
+
+<p>Whatever may be thought of such a speculation as a physical hypothesis,
+this conclusion has been verified to a considerable extent as a
+matter of fact by subsequent discovery, the result of a careful and minute
+examination and mapping down of the smaller stars in and near
+the zodiac, undertaken with that express object. Zodiacal charts of this
+kind, the product of the zeal and industry of many astronomers, have
+been constructed, in which every star down to the ninth, tenth, or even
+lower magnitudes, is inserted; and these stars being compared with the
+actual stars of the heavens, the intrusion of any stranger within their
+limits cannot fail to be noticed when the comparison is systematically<span class="pagenum"><a name="Page_89" id="Page_89">89</a></span>
+conducted. The discovery of Astræa and Hebe by Professor Hencke,
+in 1845 and 1847, revived the flagging spirit of inquiry in this direction;
+with what success, the list of fifty-two asteroids, with their names and
+the dates of their discovery, will best show. The labours of our indefatigable
+countryman, Mr. Hind, have been rewarded by the discovery of
+no less than eight of them.</p></blockquote>
+
+<h3>FIRE-BALLS AND SHOOTING STARS.</h3>
+
+<p>Humboldt relates, that a friend at Popayan, at an elevation
+of 5583 feet above the sea-level, at noon, when the sun was
+shining brightly in a cloudless sky, saw his room lighted up by
+a fire-ball: he had his back towards the window at the time,
+and on turning round, perceived that great part of the path
+traversed by the fire-ball was still illuminated by the brightest
+radiance. The Germans call these phenomena <i>star-snuff</i>, from
+the vulgar notion that the lights in the firmament undergo a
+process of snuffing, or cleaning. Other nations call it <i>a shot or
+fall of stars</i>, and the English <i>star-shoot</i>. Certain tribes of the
+Orinoco term the pearly drops of dew which cover the beautiful
+leaves of the heliconia <i>star-spit</i>. In the Lithuanian mythology,
+the nature and signification of falling stars are embodied under
+nobler and more graceful symbols. The Parcæ, <i>Werpeja</i>, weave
+in heaven for the new-born child its thread of fate, attaching
+each separate thread to a star. When death approaches the
+person, the thread is rent, and the star wanes and sinks to the
+earth.&mdash;<i>Jacob Grimm.</i></p>
+
+<h3>THEORY AND EXPERIENCE.</h3>
+
+<p>In the perpetual vicissitude of theoretical views, says the
+author of <i>Giordano Bruno</i>, “most men see nothing in philosophy
+but a succession of passing meteors; whilst even the
+grander forms in which she has revealed herself share the fate
+of comets,&mdash;bodies that do not rank in popular opinion amongst
+the external and permanent works of nature, but are regarded
+as mere fugitive apparitions of igneous vapour.”</p>
+
+<h3>METEORITES FROM THE MOON.</h3>
+
+<p>The hypothesis of the selenic origin of meteoric stones depends
+upon a number of conditions, the accidental coincidence
+of which could alone convert a possible to an actual fact. The
+view of the original existence of small planetary masses in space
+is simpler, and at the same time more analogous with those
+entertained concerning the formation of other portions of the
+solar system.</p>
+
+<blockquote>
+
+<p>Diogenes Laertius thought aerolites came from the sun; but Pliny
+derides this theory. The fall of aerolites in bright sunshine, and when
+the moon’s disc was invisible, probably led to the idea of sun-stones.
+Moreover Anaxagoras regarded the sun as “a molten fiery mass;” and<span class="pagenum"><a name="Page_90" id="Page_90">90</a></span>
+Euripides, in Phaëton, terms the sun “a golden mass,” that is to say,
+a fire-coloured, brightly-shining matter, but not leading to the inference
+that aerolites are golden sun-stones. The Greek philosophers had
+four hypotheses as to their origin: telluric, from ascending exhalations;
+masses of stone raised by hurricanes; a solar origin; and lastly, an
+origin in the regions of space, as heavenly bodies which had long remained
+invisible: the last opinion entirely according with that of the
+present day.</p>
+
+<p>Chladni states that an Italian physicist, Paolo Maria Terzago, on
+the occasion of the fall of an aerolite at Milan, in 1660, by which a Franciscan
+monk was killed, was the first who surmised that aerolites were
+of selenic origin. Without any previous knowledge of this conjecture,
+Olbers was led, in 1795 (after the celebrated fall at Siena, June 16th,
+1794), to investigate the amount of the initial tangential force that
+would be required to bring to the earth masses projected from the
+moon. Olbers, Brandes, and Chaldni thought that “the velocity of 16
+to 32 miles, with which fire-balls and shooting-stars entered our atmosphere,”
+furnished a refutation to the view of their selenic origin. According
+to Olbers, it would require to reach the earth, setting aside the
+resistance of the air, an initial velocity of 8292 feet in the second; according
+to Laplace, 7862; to Biot, 8282; and to Poisson, 7595. Laplace
+states that this velocity is only five or six times as great as that of a
+cannon-ball; but Olbers has shown that “with such an initial velocity
+as 7500 or 8000 feet in a second, meteoric stones would arrive at the
+surface of our earth with a velocity of only 35,000 feet.” But the measured
+velocity of meteoric stones averages upwards of 114,000 feet to a
+second; consequently the original velocity of projection from the moon
+must be almost 110,000 feet, and therefore 14 times greater than Laplace
+asserted. It must, however, be recollected, that the opinion then so prevalent,
+of the existence of active volcanoes in the moon, where air and
+water are absent, has since been abandoned.</p>
+
+<p>Laplace elsewhere states, that in all probability aerolites “come
+from the depths of space;” yet he in another passage inclines to the hypothesis
+of their lunar origin, always, however, assuming that the stones
+projected from the moon “become satellites of our earth, describing
+around it more or less eccentric orbits, and thus not reaching its atmosphere
+until several or even many revolutions have been accomplished.”</p>
+
+<p>In Syria there is a popular belief that aerolites chiefly fall on clear
+moonlight nights. The ancients (Pliny tells us) looked for their fall
+during lunar eclipses.&mdash;<i>Abridged from Humboldt’s Cosmos</i>, vol. i. (Bohn’s
+edition).</p></blockquote>
+
+<p>Dr. Laurence Smith, U.S., accepts the “lunar theory,” and
+considers meteorites to be masses thrown off from the moon,
+the attractive power of which is but one-sixth that of the earth;
+so that bodies thrown from the surface of the moon experience
+but one sixth the retarding force they would have when thrown
+from the earth’s surface.</p>
+
+<blockquote>
+
+<p>Look again (says Dr. Smith) at the constitution of the meteorite,
+made up principally of <i>pure</i> iron. It came evidently from some place
+where there is little or no oxygen. Now the moon has no atmosphere,
+and no water on its surface. There is no oxygen there. Hurled from
+the moon, these bodies,&mdash;these masses of almost pure iron,&mdash;would
+flame in the sun like polished steel, and on reaching our atmosphere
+would burn in its oxygen until a black oxide cooled it; and this we find<span class="pagenum"><a name="Page_91" id="Page_91">91</a></span>
+to be the case with all meteorites,&mdash;the black colour is only an external
+covering.</p></blockquote>
+
+<p>Sir Humphry Davy, from facts contained in his researches
+on flame, in 1817, conceives that the light of meteors depends,
+not upon the ignition of inflammable gases, but upon that of
+solid bodies; that such is their velocity of motion, as to excite
+sufficient heat for their ignition by the compression even of
+rare air; and that the phenomena of falling stars may be explained
+by regarding them as small incombustible bodies moving
+round the earth in very eccentric orbits, and becoming
+ignited only when they pass with immense rapidity through
+the upper regions of the atmosphere; whilst those meteors
+which throw down stony bodies are, similarly circumstanced,
+combustible masses.</p>
+
+<p>Masses of iron and nickel, having all the appearance of
+aerolites or meteoric stones, have been discovered in Siberia,
+at a depth of ten metres below the surface of the earth. From
+the fact, however, that no meteoric stones are found in the
+secondary and tertiary formations, it would seem to follow that
+the phenomena of falling stones did not take place till the earth
+assumed its present conditions.</p>
+
+<h3>VAST SHOWER OF METEORS.</h3>
+
+<p>The most magnificent Shower of Meteors that has ever been
+known was that which fell during the night of November 12th,
+1833, commencing at nine o’clock in the evening, and continuing
+till the morning sun concealed the meteors from view. This
+shower extended from Canada to the northern boundary of South
+America, and over a tract of nearly 3000 miles in width.</p>
+
+<h3>IMMENSE METEORITE.</h3>
+
+<p>Mrs. Somerville mentions a Meteorite which passed within
+twenty-five miles of our planet, and was estimated to weigh
+600,000 tons, and to move with a velocity of twenty miles in a
+second. Only a small fragment of this immense mass reached
+the earth. Four instances are recorded of persons being killed
+by their fall. A block of stone fell at Ægos Potamos, <span class="smcap smaller">B.C.</span> 465,
+as large as two millstones; another at Narni, in 921, projected
+like a rock four feet above the surface of the river, in which it
+was seen to fall. The Emperor Jehangire had a sword forged
+from a mass of meteoric iron, which fell in 1620 at Jahlinder
+in the Punjab. Sixteen instances of the fall of stones in the
+British Isles are well authenticated to have occurred since 1620,
+one of them in London. It is very remarkable that no new
+chemical element has been detected in any of the numerous
+meteorites which have been analysed.</p>
+
+<p><span class="pagenum"><a name="Page_92" id="Page_92">92</a></span></p>
+
+<h3>NO FOSSIL METEORIC STONES.</h3>
+
+<p>It is (says Olbers) a remarkable but hitherto unregarded
+fact, that while shells are found in secondary and tertiary formations,
+no Fossil Meteoric Stones have as yet been discovered.
+May we conclude from this circumstance, that previous to the
+present and last modification of the earth’s surface no meteoric
+stones fell on it, though at the present time it appears probable,
+from the researches of Schreibers, that 700 fall annually?<a name="FNanchor_24" id="FNanchor_24" href="#Footnote_24" class="fnanchor">24</a></p>
+
+<h3>THE END OF OUR SYSTEM.</h3>
+
+<p>While all the phenomena in the heavens indicate a law of
+progressive creation, in which revolving matter is distributed
+into suns and planets, there are indications in our own system
+that a period has been assigned for its duration, which, sooner
+or later, it must reach. The medium which fills universal
+space, whether it be a luminiferous ether, or arise from the
+indefinite expansion of planetary atmospheres, must retard the
+bodies which move in it, even were it 360,000 millions of times
+more rare than atmospheric air; and, with its time of revolution
+gradually shortening, the satellite must return to its
+planet, the planet to its sun, and the sun to its primeval nebula.
+The fate of our system, thus deduced from mechanical laws,
+must be the fate of all others. Motion cannot be perpetuated
+in a resisting medium; and where there exist disturbing forces,
+there must be primarily derangement, and ultimately ruin.
+From the great central mass, heat may again be summoned to
+exhale nebulous matter; chemical forces may again produce
+motion, and motion may again generate systems; but, as in
+the recurring catastrophes which have desolated our earth, the
+great First Cause must preside at the dawn of each cosmical
+cycle; and, as in the animal races which were successively reproduced,
+new celestial creations of a nobler form of beauty
+and of a higher form of permanence may yet appear in the
+sidereal universe. “Behold, I create new heavens and a new
+earth, and the former shall not be remembered.” “The new
+heavens and the new earth shall remain before me.” “Let us
+look, then, according to this promise, for the new heavens and
+the new earth, wherein dwelleth righteousness.”&mdash;<i>North-British
+Review</i>, No. 3.</p>
+
+<h3>BENEFITS OF GLASS TO MAN.</h3>
+
+<p>Cuvier eloquently says: “It could not be expected that
+those Phœnician sailors who saw the sand of the shores of
+Bætica transformed by fire into a transparent Glass, should have
+at once foreseen that this new substance would prolong the<span class="pagenum"><a name="Page_93" id="Page_93">93</a></span>
+pleasures of sight to the old; that it would one day assist the
+astronomer in penetrating the depths of the heavens, and in
+numbering the stars of the Milky Way; that it would lay open
+to the naturalist a miniature world, as populous, as rich in
+wonders as that which alone seemed to have been granted to
+his senses and his contemplation: in fine, that the most simple
+and direct use of it would enable the inhabitants of the coast
+of the Baltic Sea to build palaces more magnificent than those
+of Tyre and Memphis, and to cultivate, almost under the polar
+circle, the most delicious fruit of the torrid zone.”</p>
+
+<h3>THE GALILEAN TELESCOPE.</h3>
+
+<p>Galileo appears to be justly entitled to the honour of having
+invented that form of Telescope which still bears his name;
+while we must accord to John Lippershey, the spectacle-maker
+of Middleburg, the honour of having previously invented the
+astronomical telescope. The interest excited at Venice by
+Galileo’s invention amounted almost to frenzy. On ascending
+the tower of St. Mark, that he might use one of his telescopes
+without molestation, Galileo was recognised by a crowd in the
+street, who took possession of the wondrous tube, and detained
+the impatient philosopher for several hours, till they had successively
+witnessed its effects. These instruments were soon
+manufactured in great numbers; but were purchased merely as
+philosophical toys, and were carried by travellers into every
+corner of Europe.</p>
+
+<h3>WHAT GALILEO FIRST SAW WITH HIS TELESCOPE.</h3>
+
+<p>The moon displayed to him her mountain-ranges and her
+glens, her continents and her highlands, now lying in darkness,
+now brilliant with sunshine, and undergoing all those
+variations of light and shadow which the surface of our own
+globe presents to the alpine traveller or to the aeronaut. The
+four satellites of Jupiter illuminating their planet, and suffering
+eclipses in his shadow, like our own moon; the spots on
+the sun’s disc, proving his rotation round his axis in twenty-five
+days; the crescent phases of Venus, and the triple form
+or the imperfectly developed ring of Saturn,&mdash;were the other
+discoveries in the solar system which rewarded the diligence of
+Galileo. In the starry heavens, too, thousands of new worlds
+were discovered by his telescope; and the Pleiades alone, which
+to the unassisted eye exhibit only <i>seven</i> stars, displayed to Galileo
+no fewer than <i>forty</i>.&mdash;<i>North-British Review</i>, No. 3.</p>
+
+<blockquote>
+
+<p>The first telescope “the starry Galileo” constructed with a leaden
+tube a few inches long, with a spectacle-glass, one convex and one concave,
+at each of its extremities. It magnified three times. Telescopes
+were made in London in February 1610, a year after Galileo had completed<span class="pagenum"><a name="Page_94" id="Page_94">94</a></span>
+his own (Rigaud, <i>On Harriot’s Papers</i>, 1833). They were at first
+called <i>cylinders</i>. The telescopes which Galileo constructed, and others
+of which he made use for observing Jupiter’s satellites, the phases of
+Venus, and the solar spots, possessed the gradually-increasing powers
+of magnifying four, seven, and thirty-two linear diameters; but they
+never had a higher power.&mdash;Arago, in the <i>Annuaire</i> for 1842.</p>
+
+<p>Clock-work is now applied to the equatorial telescope, so as to allow
+the observer to follow the course of any star, comet, or planet he may
+wish to observe continuously, without using his hands for the mechanical
+motion of the instrument.</p></blockquote>
+
+<h3>ANTIQUITY OF TELESCOPES.</h3>
+
+<p>Long tubes were certainly employed by Arabian astronomers,
+and very probably also by the Greeks and Romans; the
+exactness of their observations being in some degree attributable
+to their causing the object to be seen through diopters or
+slits. Abul Hassan speaks very distinctly of tubes, to the extremities
+of which ocular and object diopters were attached;
+and instruments so constructed were used in the observatory
+founded by Hulagu at Meragha. If stars be more easily discovered
+during twilight by means of tubes, and if a star be
+sooner revealed to the naked eye through a tube than without
+it, the reason lies, as Arago has truly observed, in the circumstance
+that the tube conceals a great portion of the disturbing
+light diffused in the atmospheric strata between the star and
+the eye applied to the tube. In like manner, the tube prevents
+the lateral impression of the faint light which the particles
+of air receive at night from all the other stars in the
+firmament. The intensity of the image and the size of the
+star are apparently augmented.&mdash;<i>Humboldt’s Cosmos</i>, vol. iii.
+p. 53.</p>
+
+<h3>NEWTON’S FIRST REFLECTING TELESCOPE.</h3>
+
+<p>The year 1668 may be regarded as the date of the invention
+of Newton’s Reflecting Telescope. Five years previously, James
+Gregory had described the manner of constructing a reflecting
+telescope with two concave specula; but Newton perceived the
+disadvantages to be so great, that, according to his statement,
+he “found it necessary, before attempting any thing in the
+practice, to alter the design, and place the eye-glass at the side
+of the tube rather than at the middle.” On this improved
+principle Newton constructed his telescope, which was examined
+by Charles II.; it was presented to the Royal Society
+near the end of 1671, and is carefully preserved by that distinguished
+body, with the inscription:</p>
+
+<blockquote>
+
+<p class="center">“<span class="smcap">The first Reflecting Telescope; invented by Sir Isaac Newton,<br />
+and made with his own hands.</span>”</p></blockquote>
+
+<p>Sir David Brewster describes this telescope as consisting of
+a concave metallic speculum, the radius of curvature of which<span class="pagenum"><a name="Page_95" id="Page_95">95</a></span>
+was 12-2/3 or 13 inches, so that “it collected the sun’s rays at
+the distance of 6-1/3 inches.” The rays reflected by the speculum
+were received upon a plane metallic speculum inclined 45°
+to the axis of the tube, so as to reflect them to the side of the
+tube in which there was an aperture to receive a small tube
+with a plano-convex eye-glass whose radius was one-twelfth
+of an inch, by means of which the image formed by the speculum
+was magnified 38 times. Such was the first reflecting
+telescope applied to the heavens; but Sir David Brewster describes
+this instrument as small and ill-made; and fifty years
+elapsed before telescopes of the Newtonian form became useful
+in astronomy.</p>
+
+<h3>SIR WILLIAM HERSCHEL’S GREAT TELESCOPE AT SLOUGH.</h3>
+
+<p>The plan of this Telescope was intimated by Herschel,
+through Sir Joseph Banks, to George III., who offered to defray
+the whole expense of it; a noble act of liberality, which
+has never been imitated by any other British sovereign. Towards
+the close of 1785, accordingly, Herschel began to construct his
+reflecting telescope, <i>forty feet in length</i>, and having a speculum
+<i>fully four feet in diameter</i>. The thickness of the speculum,
+which was uniform in every part, was 3½ inches, and its weight
+nearly 2118 pounds; the metal being composed of 32 copper,
+and 10·7 of tin: it was the third speculum cast, the two previous
+attempts having failed. The speculum, when not in use,
+was preserved from damp by a tin cover, fitted upon a rim of
+close-grained cloth. The tube of the telescope was 39 ft. 4 in.
+long, and its width 4 ft. 10 in.; it was made of iron, and was
+3000 lbs. lighter than if it had been made of wood. The observer
+was seated in a suspended movable seat at the mouth
+of the tube, and viewed the image of the object with a magnifying
+lens or eye-piece. The focus of the speculum, or place
+of the image, was within four inches of the lower side of the
+mouth of the tube, and came forward into the air, so that there
+was space for part of the head above the eye, to prevent it
+from intercepting many of the rays going from the object to
+the mirror. The eye-piece moved in a tube carried by a slider
+directed to the centre of the speculum, and fixed on an adjustible
+foundation at the mouth of the tube. It was completed
+on the 27th August 1789; and <i>the very first moment</i> it
+was directed to the heavens, a new body was added to the
+solar system, namely, Saturn and six of its satellites; and in
+less than a month after, the seventh satellite of Saturn, “an
+object,” says Sir John Herschel, “of a far higher order of
+difficulty.”&mdash;<i>Abridged from the North-British Review</i>, No. 3.</p>
+
+<blockquote>
+
+<p>This magnificent instrument stood on the lawn in the rear of Sir
+William Herschel’s house at Slough; and some of our readers, like ourselves,<span class="pagenum"><a name="Page_96" id="Page_96">96</a></span>
+may remember its extraordinary aspect when seen from the
+Bath coach-road, and the road to Windsor. The difficulty of managing
+so large an instrument&mdash;requiring as it did two assistants in addition
+to the observer himself and the person employed to note the time&mdash;prevented
+its being much used. Sir John Herschel, in a letter to Mr.
+Weld, states the entire cost of its construction, 4000<i>l.</i>, was defrayed by
+George III. In 1839, the woodwork of the telescope being decayed,
+Sir John Herschel had it cleared away; and piers were erected, on
+which the tube was placed, <i>that</i> being of iron, and so well preserved
+that, although not more than one-twentieth of an inch thick, when in
+the horizontal position it contained within all Sir John’s family; and
+next the two reflectors, the polishing apparatus, and portions of the
+machinery, to the amount of a great many tons. Sir John attributes
+this great strength and resistance to the internal structure of the tube,
+very similar to that patented under the name of corrugated iron-roping.
+Sir John Herschel also thinks that system of triangular arrangement
+of the woodwork was upon the principle to which “diagonal bracing”
+owes its strength.</p></blockquote>
+
+<h3>THE EARL OF ROSSE’S GREAT REFLECTING TELESCOPE.</h3>
+
+<p>Sir David Brewster has remarked, that “the long interval
+of half a century seems to be the period of hybernation during
+which the telescopic mind rests from its labours in order to acquire
+strength for some great achievement. Fifty years elapsed
+between the dwarf telescope of Newton and the large instruments
+of Hadley; other fifty years rolled on before Sir William
+Herschel constructed his magnificent telescope; and fifty years
+more passed away before the Earl of Rosse produced that colossal
+instrument which has already achieved such brilliant discoveries.”<a name="FNanchor_25" id="FNanchor_25" href="#Footnote_25" class="fnanchor">25</a></p>
+
+<p>In the improvement of the Reflecting Telescope, the first
+object has always been to increase the magnifying power and
+light by the construction of as large a mirror as possible; and
+to this point Lord Rosse’s attention was directed as early as
+1828, the field of operation being at his lordship’s seat, Birr
+Castle at Parsonstown, about fifty miles west of Dublin. For
+this high branch of scientific inquiry Lord Rosse was well fitted
+by a rare combination of “talent to devise, patience to bear
+disappointment, perseverance, profound mathematical knowledge,
+mechanical skill, and uninterrupted leisure from other
+pursuits;”<a name="FNanchor_26" id="FNanchor_26" href="#Footnote_26" class="fnanchor">26</a> all these, however, would not have been sufficient,
+had not a great command of money been added; the gigantic
+telescope we are about to describe having cost certainly not
+less than twelve thousand pounds.</p>
+
+<blockquote>
+
+<p>Lord Rosse ground and polished specula fifteen inches, two feet, and
+three feet in diameter before he commenced the colossal instrument. It
+is impossible here to detail the admirable contrivances and processes by
+which he prepared himself for this great work. He first ascertained<span class="pagenum"><a name="Page_97" id="Page_97">97</a></span>
+the most useful combination of metals for specula, both in whiteness,
+porosity, and hardness, to be copper and tin. Of this compound the reflector
+was cast in pieces, which were fixed on a bed of zinc and copper,&mdash;a
+species of brass which expanded in the same degree by heat as the
+pieces of the speculum themselves. They were ground as one body to
+a true surface, and then polished by machinery moved by a steam-engine.
+The peculiarities of this mechanism were entirely Lord Rosse’s
+invention, and the result of close calculation and observation: they were
+chiefly, placing the speculum with the face upward, regulating the temperature
+by having it immersed in water, usually at 55° Fahr., and regulating
+the pressure and velocity. This was found to work a perfect
+spherical figure in large surfaces with a degree of precision unattainable
+by the hand; the polisher, by working above and upon the face of the
+speculum, being enabled to examine the operation as it proceeded without
+removing the speculum, which, when a ton weight, is no easy matter.</p>
+
+<p>The contrivance for doing this is very beautiful. The machine is
+placed in a room at the bottom of a high tower, in the successive floors
+of which trap-doors can be opened. A mast is elevated on the top of the
+tower, so that its summit is about ninety feet <i>above</i> the speculum. A
+dial-plate is attached to the top of the mast, and a small plane speculum
+and eye-piece, with proper adjustments, are so placed that the combination
+becomes a Newtonian telescope, and the dial-plate the object.
+The last and most important part of the process of working the speculum,
+is to give it a <i>true parabolic figure</i>, that is, such a figure that each
+portion of it should reflect the incident ray to the same focus. Lord
+Rosse’s operations for this purpose consist&mdash;1st, of a stroke of the first
+eccentric, which carries the polisher along <i>one-third</i> of the diameter of
+the speculum; 2d, a transverse stroke twenty-one times slower, and
+equal to 0·27 of the same diameter, measured on the edge of the tank,
+or 1·7 beyond the centre of the polisher; 3d, a rotation of the speculum
+performed in the same time as thirty-seven of the first strokes; and
+4th, a rotation of the polisher in the same direction about sixteen times
+slower. If these rules are attended to, the machine will give the true
+parabolic figure to the speculum, whether it be <i>six inches</i> or <i>three feet
+in diameter</i>. In the three-feet speculum, the figure is so true with the
+whole aperture, that it is thrown out of focus by a motion of less than
+the <i>thirtieth of an inch</i>, “and even with a single lens of one-eighth of
+an inch focus, giving a power of 2592, the dots on a watch-dial are still
+in some degree defined.”</p></blockquote>
+
+<p>Thus was executed the three-feet speculum for the twenty-six-feet
+telescope placed upon the lawn at Parsonstown, which,
+in 1840, showed with powers up to 1000 and even 1600; and
+which resolved nebulæ into stars, and destroyed that symmetry
+of form in globular nebulæ upon which was founded the hypothesis
+of the gradual condensation of nebulous matter into suns
+and planets.<a name="FNanchor_27" id="FNanchor_27" href="#Footnote_27" class="fnanchor">27</a></p>
+
+<p>Scarcely was this instrument out of Lord Rosse’s hands,
+when he resolved to attempt by the same processes to construct<span class="pagenum"><a name="Page_98" id="Page_98">98</a></span>
+another reflector, with a speculum <i>six feet</i> in diameter and <i>fifty
+feet long</i>! and this magnificent instrument was completed early
+in 1845. The focal length of the speculum is fifty-four feet. It
+weighs four tons, and, with its supports, is seven times as heavy
+as the four-feet speculum of Sir William Herschel. The speculum
+is placed in one of the sides of a cubical wooden box, about
+eight feet wide, and to the opposite end of this box is fastened
+the tube, which is made of deal staves an inch thick, hooped
+with iron clamp-rings, like a huge cask. It carries at its upper
+end, and in the axis of the tube, a small oval speculum, six
+inches in its lesser diameter.</p>
+
+<p>The tube is about 50 feet long and 8 feet in diameter in
+the middle, and furnished with diaphragms 6½ feet in aperture.
+The late Dean of Ely walked through the tube with an umbrella
+up.</p>
+
+<p>The telescope is established between two lofty castellated
+piers 60 feet high, and is raised to different altitudes by a
+strong chain-cable attached to the top of the tube. This cable
+passes over a pulley on a frame down to a windlass on the
+ground, which is wrought by two assistants. To the frame are
+attached chain-guys fastened to the counterweights; and the
+telescope is balanced by these counterweights suspended by
+chains, which are fixed to the sides of the tube and pass over
+large iron pulleys. The immense mass of matter weighs about
+twelve tons.</p>
+
+<p>On the eastern pier is a strong semicircle of cast-iron, with
+which the telescope is connected by a racked bar, with friction-rollers
+attached to the tube by wheelwork, so that by
+means of a handle near the eye-piece, the observer can move
+the telescope along the bar on either side of the meridian, to
+the distance of an hour for an equatorial star.</p>
+
+<p>On the western pier are stairs and galleries. The observing
+gallery is moved along a railway by means of wheels and a
+winch; and the mechanism for raising the galleries to various
+altitudes is very ingenious. Sometimes the galleries, filled with
+observers, are suspended midway between the two piers, over
+a chasm sixty feet deep.</p>
+
+<p>An excellent description of this immense Telescope at
+Birr Castle will be found in Mr. Weld’s volume of <i>Vacation
+Rambles</i>.</p>
+
+<p>Sir David Brewster thus eloquently sketches the powers of
+the telescope at the close of his able description of the instrument,
+which we have in part quoted from his <i>Life of Sir Isaac
+Newton</i>.</p>
+
+<blockquote>
+
+<p>We have, in the mornings, walked again and again, and ever with
+new delight, along its mystic tube, and at midnight, with its distinguished
+architect, pondered over the marvellous sights which it dis-<span class="pagenum"><a name="Page_99" id="Page_99">99</a></span>closes,&mdash;the
+satellites and belts and rings of Saturn,&mdash;the old and new
+ring, which is advancing with its crest of waters to the body of the
+planet,&mdash;the rocks, and mountains, and valleys, and extinct volcanoes
+of the moon,&mdash;the crescent of Venus, with its mountainous outline,&mdash;the
+systems of double and triple stars,&mdash;the nebulæ and starry clusters
+of every variety of shape,&mdash;and those spiral nebular formations which
+baffle human comprehension, and constitute the greatest achievement
+in modern discovery.</p></blockquote>
+
+<p>The Astronomer Royal, Mr. Airy, alludes to the impression
+made by the enormous light of the telescope,&mdash;partly by the
+modifications produced in the appearance of nebulæ already
+figured, partly by the great number of stars seen at a distance
+from the Milky Way, and partly from the prodigious brilliancy
+of Saturn. The account given by another astronomer of the
+appearance of Jupiter was that it resembled a coach-lamp in
+the telescope; and this well expresses the blaze of light which
+is seen in the instrument.</p>
+
+<p>The Rev. Dr. Scoresby thus records the results of his visits:</p>
+
+<blockquote>
+
+<p>The range opened to us by the great telescope at Birr Castle is best,
+perhaps, apprehended by the now usual measurement&mdash;not of distances
+in miles, or millions of miles, or diameters of the earth’s orbit, but&mdash;of
+the progress of light in free space. The determination within, no
+doubt, a small proportion of error of the parallax of a considerable
+number of the fixed stars yields, according to Mr. Peters, a space betwixt
+us and the fixed stars of the smallest magnitude, the sixth, ordinarily
+visible to the naked eye, of 130 years in the flight of light. This
+information enables us, on the principles of <i>sounding the heavens</i>, suggested
+by Sir W. Herschel, with the photometrical researches on the
+stars of Dr. Wollaston and others, to carry the estimation of distances,
+and that by no means on vague assumption, to the limits of space
+opened out by the most effective telescopes. And from the guidance
+thus afforded us as to the comparative power of the six feet speculum
+in the penetration of space as already elucidated, we might fairly assume
+the fact, that if any other telescope now in use could follow the
+sun if removed to the remotest visible position, or till its light would
+require 10,000 years to reach us, the grand instrument at Parsonstown
+would follow it so far that from 20,000 to 25,000 years would be spent in
+the transmission of its light to the earth. But in the cases of clusters
+of stars, and of nebulæ exhibiting a mere speck of misty luminosity,
+from the combined light of perhaps hundreds of thousands of suns, the
+<i>penetration</i> into space, compared with the results of ordinary vision,
+must be enormous; so that it would not be difficult to show the <i>probability</i>
+that a million of years, in flight of light, would be requisite, in
+regard to the most distant, to trace the enormous interval.</p></blockquote>
+
+<h3>GIGANTIC TELESCOPES PROPOSED.</h3>
+
+<p>Hooke is said to have proposed the use of Telescopes having
+a length of upwards of 10,000 feet (or nearly two miles), in
+order to see animals in the moon! an extravagant expectation
+which Auzout considered it necessary to refute. The Capuchin
+monk Schyrle von Rheita, who was well versed in optics, had
+already spoken of the speedy practicability of constructing telescopes<span class="pagenum"><a name="Page_100" id="Page_100">100</a></span>
+that should magnify 4000 times, by means of which
+the lunar mountains might be accurately laid down.</p>
+
+<p>Optical instruments of such enormous focal lengths remind
+us of the Arabian contrivances of measurement: quadrants with
+a radius of about 190 feet, upon whose graduated limb the
+image of the sun was received as in the gnomon, through a
+small round aperture. Such a quadrant was erected at Samarcand,
+probably constructed after the model of the older
+sextants of Alchokandi, which were about sixty feet in height.</p>
+
+<h3>LATE INVENTION OF OPTICAL INSTRUMENTS.</h3>
+
+<p>A writer in the <i>North-British Review</i>, No. 50, considers it
+strange that a variety of facts which must have presented
+themselves to the most careless observer should not have led
+to the earlier construction of Optical Instruments. The ancients,
+doubtless, must have formed metallic articles with concave
+surfaces, in which the observer could not fail to see himself
+magnified; and if the radius of the concavity exceeded
+twelve inches, twice the focal distance of his eye, he had in
+his hands an extempore reflecting telescope of the Newtonian
+form, in which the concave metal was the speculum, and his
+eye the eye-glass, and which would magnify and bring near him
+the image of objects nearly behind him. Through the spherical
+drops of water suspended before his eye, an attentive observer
+might have seen magnified some minute body placed
+accidentally in its anterior focus; and in the eyes of fishes and
+quadrupeds which he used for his food, he might have seen,
+and might have extracted, the beautiful lenses which they
+contain, and which he could not fail to regard as the principal
+agents in the vision of the animals to which they belonged.
+Curiosity might have prompted him to look through these remarkable
+lenses or spheres; and had he placed the lens of the
+smallest minnow, or that of the bird, the sheep, or the ox, in
+or before a circular aperture, he would have produced a microscope
+or microscopes of excellent quality and different magnifying
+powers. No such observations seem, however, to have
+been made; and even after the invention of glass, and its conversion
+into globular vessels, through which, when filled with
+any fluid, objects are magnified, the microscope remained undiscovered.</p>
+
+<h3>A TRIAD OF CONTEMPORARY ASTRONOMERS.</h3>
+
+<p>It is a remarkable fact in the history of astronomy (says
+Sir David Brewster), that three of its most distinguished professors
+were contemporaries. Galileo was the contemporary
+of Tycho during thirty-seven years, and of Kepler during the
+fifty-nine years of his life. Galileo was born seven years before<span class="pagenum"><a name="Page_101" id="Page_101">101</a></span>
+Kepler, and survived him nearly the same time. We have not
+learned that the intellectual triumvirate of the age enjoyed
+any opportunity for mutual congratulation. What a privilege
+would it have been to have contrasted the aristocratic dignity
+of Tycho with the reckless ease of Kepler, and the manly and
+impetuous mien of the Italian sage!&mdash;<i>Brewster’s Life of Newton.</i></p>
+
+<h3>A PEASANT ASTRONOMER.</h3>
+
+<p>At about the same time that Goodricke discovered the
+variation of the remarkable periodical star Algol, or β Persei,
+one Palitzch, a farmer of Prolitz, near Dresden,&mdash;a peasant by
+station, an astronomer by nature,&mdash;from his familiar acquaintance
+with the aspect of the heavens, was led to notice, among
+so many thousand stars, Algol, as distinguished from the rest
+by its variation, and ascertained its period. The same Palitzch
+was also the first to re-discover the predicted comet of Halley
+in 1759, which he saw nearly a month before any of the astronomers,
+who, armed with their telescopes, were anxiously
+watching its return. These anecdotes carry us back to the era
+of the Chaldean shepherds.&mdash;<i>Sir John Herschel’s Outlines.</i></p>
+
+<h3>SHIRBURN-CASTLE OBSERVATORY.</h3>
+
+<p>Lord Macclesfield, the eminent mathematician, who was
+twelve years President of the Royal Society, built at his seat,
+Shirburn Castle in Oxfordshire, an Observatory, about 1739.
+It stood 100 yards south from the castle-gate, and consisted of
+a bed-chamber, a room for the transit, and the third for a mural
+quadrant. In the possession of the Royal Astronomical Society
+is a curious print representing two of Lord Macclesfield’s
+servants taking observations in the Shirburn observatory; they
+are Thomas Phelps, aged 82, who, from being a stable-boy to
+Lord-Chancellor Macclesfield, rose by his merit and genius to
+be appointed observer. His companion is John Bartlett, originally
+a shepherd, in which station he, by books and observation,
+acquired such a knowledge in computation, and of the
+heavenly bodies, as to induce Lord Macclesfield to appoint
+him assistant-observer in his observatory. Phelps was the
+person who, on December 23d, 1743, discovered the great
+comet, and made the first observation of it; an account of
+which is entered in the <i>Philosophical Transactions</i>, but not the
+name of the observer.</p>
+
+<h3>LACAILLE’S OBSERVATORY.</h3>
+
+<p>Lacaille, who made more observations than all his contemporaries
+put together, and whose researches will have the
+highest value as long as astronomy is cultivated, had an observatory
+at the Collège Mazarin, part of which is now the
+Palace of the Institute, at Paris.</p>
+
+<p><span class="pagenum"><a name="Page_102" id="Page_102">102</a></span></p>
+
+<blockquote>
+
+<p>For a long time it had been without observer or instruments; under
+Napoleon’s reign it was demolished. Lacaille never used to illuminate
+the wires of his instruments. The inner part of his observatory was
+painted black; he admitted only the faintest light, to enable him to
+see his pendulum and his paper: his left eye was devoted to the service
+of looking to the pendulum, whilst his right eye was kept shut. The
+latter was only employed to look to the telescope, and during the time
+of observation never opened but for this purpose. Thus the faintest
+light made him distinguish the wires, and he very seldom felt the necessity
+of illuminating them. Part of these blackened walls were visible
+long after the demolition of the observatory, which took place somewhat
+about 1811.&mdash;<i>Professor Mohl.</i></p></blockquote>
+
+<h3>NICETY REQUIRED IN ASTRONOMICAL CALCULATIONS.</h3>
+
+<p>In the <i>Edinburgh Review</i>, 1850, we find the following illustrations
+of the enormous propagation of minute errors:</p>
+
+<blockquote>
+
+<p>The rod used in measuring a base-line is commonly about ten feet
+long; and the astronomer may be said truly to apply that very rod to
+mete the distance of the stars. An error in placing a fine dot which
+fixes the length of the rod, amounting to one-five-thousandth of an inch
+(the thickness of a single silken fibre), will amount to an error of 70
+feet in the earth’s diameter, of 316 miles in the sun’s distance, and to
+65,200,000 miles in that of the nearest fixed star. Secondly, as the
+astronomer in his observatory has nothing further to do with ascertaining
+lengths or distances, except by calculation, his whole skill and artifice
+are exhausted in the measurement of angles; for by these alone
+spaces inaccessible can be compared. Happily, a ray of light is straight:
+were it not so (in celestial spaces at least), there would be an end of
+our astronomy. Now an angle of a second (3600 to a degree) is a subtle
+thing. It has an apparent breadth utterly invisible to the unassisted
+eye, unless accompanied with so intense a splendour (<i>e. g.</i> in the case of
+a fixed star) as actually to raise by its effect on the nerve of sight a
+spurious image having a sensible breadth. A silkworm’s fibre, such as
+we have mentioned above, subtends an angle of a second at 3½ feet
+distance; a cricket-ball, 2½ inches diameter, must be removed, in order
+to subtend a second, to 43,000 feet, or about 8 miles, where it would
+be utterly invisible to the sharpest sight aided even by a telescope of
+some power. Yet it is on the measure of one single second that the
+ascertainment of a sensible parallax in any fixed star depends; and an
+error of one-thousandth of that amount (a quantity still unmeasurable
+by the most perfect of our instruments) would place the star too far or
+too near by 200,000,000,000 miles; a space which light requires 118 days
+to travel.</p></blockquote>
+
+<h3>CAN STARS BE SEEN BY DAYLIGHT?</h3>
+
+<p>Aristotle maintains that Stars may occasionally be seen in
+the Daylight, from caverns and cisterns, as through tubes.
+Pliny alludes to the same circumstance, and mentions that
+stars have been most distinctly recognised during solar eclipses.
+Sir John Herschel has heard it stated by a celebrated optician,
+that his attention was first drawn to astronomy by the regular
+appearance, at a certain hour, for several successive days, of a
+considerable star through the shaft of a chimney. The chimney-sweepers
+who have been questioned upon this subject agree<span class="pagenum"><a name="Page_103" id="Page_103">103</a></span>
+tolerably well in stating that “they have never seen stars by
+day, but that when observed at night through deep shafts, the
+sky appeared quite near, and the stars larger.” Saussure states
+that stars have been seen with the naked eye in broad daylight,
+on the declivity of Mont Blanc, at an elevation of 12,757
+feet, as he was assured by several of the alpine guides. The
+observer must be placed entirely in the shade, and have a thick
+and massive shade above his head, else the stronger light of
+the air will disperse the faint image of the stars; these conditions
+resembling those presented by the cisterns of the ancients,
+and the chimneys above referred to. Humboldt, however,
+questions the accuracy of these evidences, adding that in the
+Cordilleras of Mexico, Quito, and Peru, at elevations of 15,000
+or 16,000 feet above the sea-level, he never could distinguish
+stars by daylight. Yet, under the ethereally pure sky of Cumana,
+in the plains near the sea-shore, Humboldt has frequently
+been able, after observing an eclipse of Jupiter’s satellites,
+to find the planet again with the naked eye, and has
+most distinctly seen it when the sun’s disc was from 18° to 20°
+above the horizon.</p>
+
+<h3>LOST HEAT OF THE SUN.</h3>
+
+<p>By the nature of our atmosphere, we are protected from
+the influence of the full flood of solar heat. The absorption
+of caloric by the air has been calculated at about one-fifth of
+the whole in passing through a column of 6000 feet, estimated
+near the earth’s surface. And we are enabled, knowing the
+increasing rarity of the upper regions of our gaseous envelope,
+in which the absorption is constantly diminishing, to prove
+that <i>about one-third of the solar heat is lost</i> by vertical transmission
+through the whole extent of our atmosphere.&mdash;<i>J.&nbsp;D.
+Forbes, F.R.S.</i>; <i>Bakerian Lecture</i>, 1842.</p>
+
+<h3>THE LONDON MONUMENT USED AS AN OBSERVATORY.</h3>
+
+<p>Soon after the completion of the Monument on Fish Street
+Hill, by Wren, in 1677, it was used by Hooke and other members
+of the Royal Society for astronomical purposes, but abandoned
+on account of the vibrations being too great for the
+nicety required in their observations. Hence arose <i>the report
+that the Monument was unsafe</i>, which has been revived in our
+time; “but,” says Elmes, “its scientific construction may bid
+defiance to the attacks of all but earthquakes for centuries to
+come.” This vibration in lofty columns is not uncommon.
+Captain Smythe, in his <i>Cycle of Celestial Objects</i>, tells us, that
+when taking observations on the summit of Pompey’s Pillar,
+near Alexandria, the mercury was sensibly affected by tremor,
+although the pillar is a solid.</p>
+
+<hr />
+
+<p><span class="pagenum"><a name="Page_104" id="Page_104">104</a></span></p>
+
+<div class="chapter"></div>
+<h2><a name="Geology" id="Geology"></a>Geology and Paleontology.</h2>
+
+<h3>IDENTITY OF ASTRONOMY AND GEOLOGY.</h3>
+
+<p>While the Astronomer is studying the form and condition and
+structure of the planets, in so far as the eye and the telescope
+can aid him, the Geologist is investigating the form and condition
+and structure of the planet to which he belongs; and it
+is from the analogy of the earth’s structure, as thus ascertained,
+that the astronomer is enabled to form any rational conjecture
+respecting the nature and constitution of the other planetary bodies.
+Astronomy and Geology, therefore, constitute the same
+science&mdash;the science of material or inorganic nature.</p>
+
+<p>When the astronomer first surveys the <i>concavity</i> of the celestial
+vault, he finds it studded with luminous bodies differing
+in magnitude and lustre, some moving to the east and others
+to the west; while by far the greater number seem fixed in
+space; and it is the business of astronomers to assign to each
+of them its proper place and sphere, to determine their true
+distance from the earth, and to arrange them in systems
+throughout the regions of sidereal space.</p>
+
+<p>In like manner, when the geologist surveys the <i>convexity</i> of
+his own globe, he finds its solid covering composed of rocks
+and beds of all shapes and kinds, lying at every possible angle,
+occupying every possible position, and all of them, generally
+speaking, at the same distance from the earth’s centre. Every
+where we see what was deep brought into visible relation with
+what was superficial&mdash;what is old with what is new&mdash;what
+preceded life with what followed it.</p>
+
+<p>Thus displayed on the surface of his globe, it becomes the
+business of the geologist to ascertain how these rocks came
+into their present places, to determine their different ages,
+and to fix the positions which they originally occupied, and
+consequently their different distances from the centre or the
+circumference of the earth. Raised from their original bed,
+the geologist must study the internal forces by which they
+were upheaved, and the agencies by which they were indurated;
+and when he finds that strata of every kind, from the primitive
+granite to the recent tertiary marine mud, have been thus
+brought within his reach, and prepared for his analysis, he
+reads their respective ages in the organic remains which they
+entomb; he studies the manner in which they have perished,<span class="pagenum"><a name="Page_105" id="Page_105">105</a></span>
+and he counts the cycles of time and of life which they disclose.&mdash;<i>Abridged
+from the North-British Review</i>, No. 9.</p>
+
+<h3>THE GEOLOGY OF ENGLAND</h3>
+
+<p class="in0">is more interesting than that of other countries, because our
+island is in a great measure an epitome of the globe; and the
+observer who is familiar with our strata, and the fossil remains
+which they include, has not only prepared himself for similar
+inquiries in other countries, but is already, as it were, by anticipation,
+acquainted with what he is to find there.&mdash;<i>Transactions
+of the Geological Society.</i></p>
+
+<h3>PROBABLE ORIGIN OF THE ENGLISH CHANNEL.</h3>
+
+<p>The proposed construction of a submarine tunnel across the
+Straits of Dover has led M. Boué, For. Mem. Geol. Soc., to
+point out the probability that the English Channel has not
+been excavated by water-action only; but owes its origin to
+one of the lines of disturbance which have fissured this portion
+of the earth’s crust: and taking this view of the case, the fissure
+probably still exists, being merely filled with comparatively
+loose material, so as to prove a serious obstacle to any
+attempt made to drive through it a submarine tunnel.&mdash;<i>Proceedings
+of the Geological Society.</i></p>
+
+<h3>HOW BOULDERS ARE TRANSPORTED TO GREAT HEIGHTS.</h3>
+
+<p>Sir Roderick Murchison has shown that in Russia, when
+the Dwina is at its maximum height, and penetrates into the
+chinks of its limestone banks, when frozen and expanded
+it causes disruptions of the rock, the entanglement of stony
+fragments in the ice. In remarkable spring floods, the stream
+so expands that in bursting it throws up its icy fragments to
+15 or 20 feet above the stream; and the waters subsiding,
+these lateral ice-heaps melt away, and leave upon the bank the
+rifled and angular blocks as evidence of the highest ice-mark.
+In Lapland, M. Böhtlingk assures us that he has found <i>large
+granitic boulders weighing several tons actually entangled and
+suspended, like birds’-nests, in the branches of pine-trees, at heights
+of 30 or 40 feet above the summer level of the stream</i>!<a name="FNanchor_28" id="FNanchor_28" href="#Footnote_28" class="fnanchor">28</a></p>
+
+<p><span class="pagenum"><a name="Page_106" id="Page_106">106</a></span></p>
+
+<h3>WHY SEA-SHELLS ARE FOUND AT GREAT HEIGHTS.</h3>
+
+<p>The action of subterranean forces in breaking through and
+elevating strata of sedimentary rocks,&mdash;of which the coast of
+Chili, in consequence of a great earthquake, furnishes an example,&mdash;leads
+to the assumption that the pelagic shells found
+by MM. Bonpland and Humboldt on the ridge of the Andes, at
+an elevation of more than 15,000 English feet, may have been
+conveyed to so extraordinary a position, not by a rising of the
+ocean, but by the agency of volcanic forces capable of elevating
+into ridges the softened crust of the earth.</p>
+
+<h3>SAND OF THE SEA AND DESERT.</h3>
+
+<p>That sand is an assemblage of small stones may be seen
+with the eye unarmed with art; yet how few are equally aware
+of the synonymous nature of the sand of the sea and of the
+land! Quartz, in the form of sand, covers almost entirely the
+bottom of the sea. It is spread over the banks of rivers, and
+forms vast plains, even at a very considerable elevation above
+the level of the sea, as the desert of Sahara in Africa, of Kobi
+in Asia, and many others. This quartz is produced, at least
+in part, from the disintegration of the primitive granite rocks.
+The currents of water carry it along, and when it is in very
+small, light, and rounded grains, even the wind transports it
+from one place to another. The hills are thus made to move
+like waves, and a deluge of sand frequently inundates the
+neighbouring countries:</p>
+
+<div class="poem-container">
+<div class="poem"><div class="stanza">
+<span class="iq">“So where o’er wide Numidian wastes extend,<br /></span>
+<span class="i0">Sudden the impetuous hurricanes descend.”&mdash;<i>Addison’s Cato.</i><br /></span>
+</div></div>
+</div>
+
+<p>To illustrate the trite axiom, that nothing is lost, let us
+glance at the most important use of sand:</p>
+
+<blockquote>
+
+<p>“Quartz in the form of sand,” observes Maltebrun, “furnishes, by
+fusion, one of the most useful substances we have, namely glass, which,
+being less hard than the crystals of quartz, can be made equally transparent,
+and is equally serviceable to our wants and to our pleasures.
+There it shines in walls of crystal in the palaces of the great, reflecting
+the charms of a hundred assembled beauties; there, in the hand of the
+philosopher, it discovers to us the worlds that revolve above us in the
+immensity of space, and the no less astonishing wonders that we tread
+beneath our feet.”</p></blockquote>
+
+<h3>PEBBLES.</h3>
+
+<p>The various heights and situations at which Pebbles are
+found have led to many erroneous conclusions as to the period
+of changes of the earth’s surface. All the banks of rivers and
+lakes, and the shores of the sea, are covered with pebbles,
+rounded by the waves which have rolled them against each<span class="pagenum"><a name="Page_107" id="Page_107">107</a></span>
+other, and which frequently seem to have brought them from
+a distance. There are also similar masses of pebbles found
+at very great elevations, to which the sea appears never to
+have been able to reach. We find them in the Alps at Valorsina,
+more than 6000 feet above the level of the sea; and on
+the mountain of Bon Homme, which is more than 1000 feet
+higher. There are some places little elevated above the level
+of the sea, which, like the famous plain of Crau, in Provence,
+are entirely paved with pebbles; while in Norway, near Quedlia,
+some mountains of considerable magnitude seem to be
+completely formed of them, and in such a manner that the
+largest pebbles occupy the summit, and their thickness and
+size diminish as you approach the base. We may include in
+the number of these confused and irregular heaps most of the
+depositions of matter brought by the river or sea, and left on
+the banks, and perhaps even those immense beds of sand which
+cover the centre of Asia and Africa. It is this circumstance
+which renders so uncertain the distinction, which it is nevertheless
+necessary to establish, between alluvial masses created
+before the commencement of history, and those which we see
+still forming under our own eyes.</p>
+
+<p>A charming monograph, entitled “Thoughts on a Pebble,”
+full of playful sentiment and graceful fancy, has been written
+by the amiable Dr. Mantell, the geologist.</p>
+
+<h3>ELEVATION OF MOUNTAIN-CHAINS.</h3>
+
+<p>Professor Ansted, in his <i>Ancient World</i>, thus characterises
+this phenomenon:</p>
+
+<blockquote>
+
+<p>These movements, described in a few words, were doubtless going
+on for many thousands and tens of thousands of revolutions of our
+planet. They were accompanied also by vast but slow changes of other
+kinds. The expansive force employed in lifting up, by mighty movements,
+the northern portion of the continent of Asia, found partial vent;
+and from partial subaqueous fissures there were poured out the tabular
+masses of basalt occurring in Central India; while an extensive area of
+depression in the Indian Ocean, marked by the coral islands of the
+Laccadives, the Maldives, the great Chagos bank, and some others, were
+in the course of depression by a counteracting movement.</p></blockquote>
+
+<p>Hitherto the processes of denudation and of elevation have
+been so far balanced as to preserve a pretty steady proportion
+of sea and dry land during geological ages; but if the internal
+temperature should be so far reduced as to be no longer capable
+of generating forces of expansion sufficient for this elevatory
+action, while the denuding forces should continue to
+act with unabated energy, the inevitable result would be, that
+every mountain-top would be in time brought low. No earthly
+barrier could declare to the ocean that there its proud waves
+should be stayed. Nothing would stop its ravages till all dry<span class="pagenum"><a name="Page_108" id="Page_108">108</a></span>
+land should be laid prostrate, to form the bed over which it
+would continue to roll an uninterrupted sea.</p>
+
+<h3>THE CHALK FORMATION.</h3>
+
+<p>Mr. Horner, F.R.S., among other things in his researches
+in the Delta, considers it extremely probable that every particle
+of Chalk in the world has at some period been circulating
+in the system of a living animal.</p>
+
+<h3>WEAR OF BUILDING-STONES.</h3>
+
+<p>Professor Henry, in an account of testing the marbles used
+in building the Capitol at Washington, states that every flash
+of lightning produces an appreciable amount of nitric acid,
+which, diffused in rain-water, acts on the carbonate of lime;
+and from specimens subjected to actual freezing, it was found
+that in ten thousand years one inch would be worn from the
+blocks by the action of frost.</p>
+
+<blockquote>
+
+<p>In 1839, a report of the examination of Sandstones, Limestones,
+and Oolites of Britain was made to the Government, with a view
+to the selection of the best material for building the new Houses of
+Parliament. For this purpose, 103 quarries were described, 96 buildings
+in England referred to, many chemical analyses of the stones were
+given, and a great number of experiments related, showing, among
+other points, the cohesive power of each stone, and the amount of disintegration
+apparent, when subjected to Brard’s process. The magnesian
+limestone, or dolomite of Bolsover Moor, was recommended, and
+finally adopted for the Houses; but the selection does not appear to
+have been so successful as might have been expected from the skill and
+labour of the investigation. It may be interesting to add, that the
+publication of the above Report (for which see <i>Year-Book of Facts</i>, 1840,
+pp. 78&ndash;80) occasioned Mr. John Mallcott to remark in the <i>Times</i> journal,
+“that all stone made use of in the immediate neighbourhood of its own
+quarries is more likely to endure that atmosphere than if it be removed
+therefrom, though only thirty or forty miles:” and the lapse of comparatively
+few years has proved the soundness of this observation.<a name="FNanchor_29" id="FNanchor_29" href="#Footnote_29" class="fnanchor">29</a></p></blockquote>
+
+<h3>PHENOMENA OF GLACIERS ILLUSTRATED.</h3>
+
+<p>Professor Tyndall, being desirous of investigating some of
+the phenomena presented by the large masses of mountain-ice,&mdash;those
+frozen rivers called Glaciers,&mdash;devised the plan of sending
+a destructive agent into the midst of a mass of ice, so as
+to break down its structure in the interior, in order to see if
+this method would reveal any thing of its internal constitution.
+Taking advantage of the bright weather of 1857, he concentrated
+a beam of sunlight by a condensing lens, so as to<span class="pagenum"><a name="Page_109" id="Page_109">109</a></span>
+form the focus of the sun’s rays in the midst of a mass of ice.
+A portion of the ice was melted, but the surrounding parts
+shone out as brilliant stars, produced by the reflection of the
+faces of the crystalline structure. On examining these brilliant
+portions with a lens, Professor Tyndall discovered that
+the structure of the ice had been broken down in symmetrical
+forms of great beauty, presenting minute stars, surrounded by
+six petals, forming a beautiful flower, the plane being always
+parallel to the plane of congelation of the ice. He then prepared
+a piece of ice, by making both its surfaces smooth and
+parallel to each other. He concentrated in the centre of the
+ice the rays of heat from the electric light; and then, placing
+the piece of ice in the electric microscope, the disc revealed
+these beautiful ice-flowers.</p>
+
+<p>A mass of ice was crushed into fragments; the small fragments
+were then placed in a cup of wood; a hollow wooden
+die, somewhat smaller than the cup, was then pressed into the
+cup of ice-fragments by the pressure of a hydraulic press, and
+the ice-fragments were immediately united into a compact cup
+of nearly transparent ice. This pressure of fragments of ice
+into a solid mass explains the formation of the glaciers and
+their origin. They are composed of particles of ice or snow;
+as they descend the sides of the mountain, the pressure of
+the snow becomes sufficiently great to compress the mass into
+solid ice, until it becomes so great as to form the beautiful
+blue ice of the glaciers. This compression, however, will not
+form the solid mass unless the temperature of the ice be
+near that of freezing water. To prove this, the lecturer cooled
+a mass of ice, by wrapping it in a piece of tinfoil and exposing
+it for some time to a bath of the ethereal solution of
+solidified carbonic-acid gas, the coldest freezing mixture known.
+This cooled mass of ice was crushed to fragments, and submitted
+to the same pressure which the other fragments had
+been exposed to without cohering in the slightest degree.&mdash;<i>Lecture
+at the Royal Institution</i>, 1858.</p>
+
+<h3>ANTIQUITY OF GLACIERS.</h3>
+
+<p>The importance of glacier agency in the past as well as
+the present condition of the earth, is undoubtedly very great.
+One of our most accomplished and ingenious geologists has,
+indeed, carried back the existence of Glaciers to an epoch of
+dim antiquity, even in the reckoning of that science whose
+chronology is counted in millions of years. Professor Ramsay
+has shown ground for believing that in the fragments of rock
+that go to make up the conglomerates of the Permian strata,
+intermediate between the Old and the New Red Sandstone,
+there is still preserved a record of the action of ice, either in<span class="pagenum"><a name="Page_110" id="Page_110">110</a></span>
+glaciers or floating icebergs, before those strata were consolidated.&mdash;<i>Saturday
+Review</i>, No. 142.</p>
+
+<h3>FLOW OF THE MER DE GLACE.</h3>
+
+<p>Michel Devouasson of Chamouni fell into a crevasse on the
+Glacier of Talefre, a feeder of the Mer de Glace, on the 29th
+of July 1836, and after a severe struggle extricated himself,
+leaving his knapsack below. The identical knapsack reappeared
+in July 1846, at a spot on the surface of the glacier
+<i>four thousand three hundred</i> feet from the place where it was
+lost, as ascertained by Professor Forbes, who himself collected
+the fragments; thus indicating the rate of flow of the icy river
+in the intervening ten years.&mdash;<i>Quarterly Review</i>, No. 202.</p>
+
+<h3>THE ALLUVIAL LAND OF EGYPT: ANCIENT POTTERY.</h3>
+
+<p>Mr. L. Horner, in his recent researches near Cairo, with the
+view of throwing light upon the geological history of the alluvial
+land of Egypt, obtained from the lowest part of the boring
+of the sediment at the colossal statue of Rameses, at a depth of
+thirty-nine feet, this curious relic of the ancient world; the
+boring instrument bringing up a fragment of pottery about an
+inch square and a quarter of an inch in thickness&mdash;the two
+surfaces being of a brick-red colour, the interior dark gray.
+According to Mr. Horner’s deductions, this fragment, having
+been found at a depth of 39 feet (if there be no fallacy in his
+reasoning), must be held to be a record of the existence of man
+13,375 years before <span class="smcap smaller">A.D.</span> 1858, reckoning by the calculated rate
+of increase of three inches and a half of alluvium in a century&mdash;11,517
+years before the Christian era, and 7625 before the
+beginning assigned by Lepsius to the reign of Menos, the
+founder of Memphis. Moreover it proves in his opinion, that
+man had already reached a state of civilisation, so far at least
+as to be able to fashion clay into vessels, and to know how
+to harden it by the action of strong heat. This calculation is
+supported by the Chevalier Bunsen, who is of opinion that the
+first epochs of the history of the human race demand at the
+least a period of 20,000 years before our era as a fair starting-point
+in the earth’s history.&mdash;<i>Proceedings of Royal Soc.</i>, 1858.</p>
+
+<blockquote>
+
+<p>Upon this theory, a Correspondent, “An Old Indigo-Planter,” writes
+to the <i>Athenæum</i>, No. 1509, the following suggestive note: “Having lived
+many years on the banks of the Ganges, I have seen the stream encroach
+on a village, undermining the bank where it stood, and deposit, as a
+natural result, bricks, pottery, &amp;c. in the bottom of the stream. On
+one occasion, I am certain that the depth of the stream where the bank
+was breaking was above 40 feet; yet in three years the current of the
+river drifted so much, that a fresh deposit of soil took place over the
+<i>débris</i> of the village, and the earth was raised to a level with the old
+bank. Now had our traveller then obtained a bit of pottery from where
+it had lain for only three years, could he reasonably draw the inference
+that it had been made 13,000 years before?”</p></blockquote>
+
+<p><span class="pagenum"><a name="Page_111" id="Page_111">111</a></span></p>
+
+<h3>SUCCESSIVE CHANGES OF THE TEMPLE OF SERAPIS.</h3>
+
+<p>The Temple of Serapis at Puzzuoli, near Naples, is perhaps,
+of all the structures raised by the hands of man, the one
+which affords most instruction to a geologist. It has not only
+undergone a wonderful succession of changes in past time, but
+is still undergoing changes of condition. This edifice was exhumed
+in 1750 from the eastern shore of the Bay of Baiæ, consisting
+partly of strata containing marine shells with fragments
+of pottery and sculpture, and partly of volcanic matter
+of sub-aerial origin. Various theories were proposed in the last
+century to explain the perforations and attached animals observed
+on the middle zone of the three erect marble columns
+until recently standing; Goethe, among the rest, suggesting
+that a lagoon had once existed in the vestibule of the temple,
+filled during a temporary incursion of the sea with salt water,
+and that marine mollusca and annelids flourished for years in
+this lagoon at twelve feet or more above the sea-level.</p>
+
+<p>This hypothesis was advanced at a time when almost any
+amount of fluctuation in the level of the sea was thought more
+probable than the slightest alteration in the level of the solid
+land. In 1807 the architect Niccolini observed that the pavement
+of the temple was dry, except when a violent south wind
+was blowing; whereas, on revisiting the temple fifteen years
+later, he found the pavement covered by salt water twice every
+day at high tide. From measurements made from 1822 to
+1838, and thence to 1845, he inferred that the sea was gaining
+annually upon the floor of the temple at the rate of about one-third
+of an inch during the first period, and about three-fourths
+of an inch during the second. Mr. Smith of Jordan Hill, from
+his visits in 1819 and 1845, found an average rise of about an
+inch annually, which was in accordance with visits made by
+Mr. Babbage in 1828, and Professor James Forbes in 1826 and
+1843. In 1852 Signor Scaecchi, at the request of Sir Charles
+Lyell, compared the depth of water on the pavement with its
+level taken by him in 1839, and found that it had gained only
+4½ inches in thirteen years, and was not so deep as when MM.
+Niccolini and Smith measured it in 1845; from which he inferred
+that after 1845 the downward movement of the land
+had ceased, and before 1852 had been converted into an upward
+movement.</p>
+
+<p>Arago and others maintained that the surface on which the
+temple stands has been depressed, has <i>remained under the sea,
+and has again been elevated</i>. Russager, however, contends that
+there is nothing in the vicinity of the temple, or in the temple
+itself, to justify this bold hypothesis. Every thing leads to the
+belief that the temple has remained unchanged in the position<span class="pagenum"><a name="Page_112" id="Page_112">112</a></span>
+in which it was originally built; but that the sea rose, surrounded
+it to a height of at least twelve feet, and again retired;
+but the elevated position of the sea continued sufficiently
+long to admit of the animals boring the pillars. This view can
+even be proved historically; for Niccolini, in a memoir published
+in 1840, gives the heights of the level of the sea in the
+Bay of Naples for a period of 1900 years, and has with much
+acuteness proved his assertions historically. The correctness
+of Russager’s opinion, he states, can be demonstrated and reduced
+to figures by means of the dates collected by Niccolini.&mdash;See
+<i>Jameson’s Journal</i>, No. 58.</p>
+
+<p>At the present time the floor is always covered with sea-water.
+On the whole, there is little doubt that the ground has sunk
+upwards of two feet during the last half-century. This gradual
+subsidence confirms in a remarkable manner Mr. Babbage’s
+conclusions&mdash;drawn from the calcareous incrustations formed
+by the hot springs on the walls of the building and from the
+ancient lines of the water-level at the base of the three columns&mdash;that
+the original subsidence was not sudden, but slow and
+by successive movements.</p>
+
+<p>Sir Charles Lyell (who, in his <i>Principles of Geology</i>, has
+given a detailed account of the several upfillings of the temple)
+considers that when the mosaic pavement was re-constructed,
+the floor of the building must have stood about twelve feet
+above the level of 1838 (or about 11½ feet above the level of the
+sea), and that it had sunk about nineteen feet below that level
+before it was elevated by the eruption of Monte Nuovo.</p>
+
+<p>We regret to add, that the columns of the temple are no
+longer in the position in which they served so many years as a
+species of self-registering hydrometer: the materials have been
+newly arranged, and thus has been torn as it were from history
+a page which can never be replaced.</p>
+
+<h3>THE GROTTO DEL CANE.</h3>
+
+<p>This “Dog Grotto” has been so much cited for its stratum
+of carbonic-acid gas covering the floor, that all geological travellers
+who visit Naples feel an interest in seeing the wonder.</p>
+
+<p>This cavern was known to Pliny. It is continually exhaling
+from its sides and floor volumes of steam mixed with carbonic-acid
+gas; but the latter, from its greater specific gravity, accumulates
+at the bottom, and flows over the step of the door.
+The upper part of the cave, therefore, is free from the gas,
+while the floor is completely covered by it. Addison, on his
+visit, made some interesting experiments. He found that a
+pistol could not be fired at the bottom; and that on laying a
+train of gunpowder and igniting it on the outside of the cavern,
+the carbonic-acid gas “could not intercept the train of<span class="pagenum"><a name="Page_113" id="Page_113">113</a></span>
+fire when it once began flashing, nor hinder it from running to
+the very end.” He found that a viper was nine minutes in
+dying on the first trial, and ten minutes on the second; this
+increased vitality being, in his opinion, attributable to the
+stock of air which it had inhaled after the first trial. Dr.
+Daubeny found that phosphorus would continue lighted at
+about two feet above the bottom; that a sulphur-match went
+out in a few minutes above it, and a wax-taper at a still higher
+level. The keeper of the cavern has a dog, upon which he
+shows the effects of the gas, which, however, are quite as well,
+if not better, seen in a torch, a lighted candle, or a pistol.</p>
+
+<p>“Unfortunately,” says Professor Silliman, “like some other
+grottoes, the enchantment of the ‘Dog Grotto’ disappears on
+a near view.” It is a little hole dug artificially in the side of a
+hill facing Lake Agnano: it is scarcely high enough for a person
+to stand upright in, and the aperture is closed by a door.
+Into this narrow cell a poor little dog is very unwillingly dragged
+and placed in a depression of the floor, where he is soon narcotised
+by the carbonic acid. The earth is warm to the hand,
+and the gas given out is very constant.</p>
+
+<h3>THE WATERS OF THE GLOBE GRADUALLY DECREASING.</h3>
+
+<p>This was maintained by M. Bory Saint Vincent, because
+the vast deserts of sand, mixed up with the salt and remains of
+marine animals, of which the surface of the globe is partly composed,
+were formerly inland seas, which have insensibly become
+dry. The Caspian, the Dead Sea, the Lake Baikal, &amp;c. will
+become dry in their turn also, when their beds will be sandy
+deserts. The inland seas, whether they have only one outlet,
+as the Mediterranean, the Red Sea, the Baltic, &amp;c., or whether
+they have several, as the Gulf of Mexico, the seas of O’Kotsk,
+of Japan, China, &amp;c., will at some future time cease to communicate
+with the great basins of the ocean; they will become
+inland seas, true Caspians, and in due time will become likewise
+dry. On all sides the waters of rivers are seen to carry
+forward in their course the soil of the continent. Alluvial
+lands, deltas, banks of sand, form themselves near the coasts,
+and in the directions of the currents; madreporic animals lay
+the foundations of new lands; and while the straits become
+closed, while the depths of the sea fill up, the level of the sea,
+which it would seem natural should become higher, is sensibly
+lower. There is, therefore, an actual diminution of liquid
+matter.</p>
+
+<h3>THE SALT LAKE OF UTAH.</h3>
+
+<p>Lieutenant Gunnison, who has surveyed the great basin of
+the Salt Lake, states the water to be about one-third salt,<span class="pagenum"><a name="Page_114" id="Page_114">114</a></span>
+which it yields on boiling. Its density is considerably greater
+than that of the Red Sea. One can hardly get the whole body
+below the surface: in a sitting position the head and shoulders
+will remain above the water, such is the strength of the brine;
+and on coming to the shore the body is covered with an incrustation
+of salt in fine crystals. During summer the lake throws
+on shore abundance of salt, while in winter it throws up Glauber
+salt plentifully. “The reason of this,” says Lieutenant
+Gunnison, “is left for the scientific to judge, and also what
+becomes of the enormous amount of fresh water poured into it
+by three or four large rivers,&mdash;Jordan, Bear, and Weber,&mdash;as
+there is no visible effect.”</p>
+
+<h3>FORCE OF RUNNING WATER.</h3>
+
+<p>It has been proved by experiment that the rapidity at the
+bottom of a stream is every where less than in any other part of
+it, and is greatest at the surface. Also, that in the middle of
+the stream the particles at the top move swifter than those at
+the sides. This slowness of the lowest and side currents is produced
+by friction; and when the rapidity is sufficiently great,
+the soil composing the sides and bottom gives way. If the water
+flows at the rate of three inches per second, it will tear up fine
+clay; six inches per second, fine sand; twelve inches per second,
+fine gravel; and three feet per second, stones the size of an
+egg.&mdash;<i>Sir Charles Lyell.</i></p>
+
+<h3>THE ARTESIAN WELL OF GRENELLE AT PARIS.</h3>
+
+<p>M. Peligot has ascertained that the Water of the Artesian
+Well of Grenelle contains not the least trace of air. Subterranean
+waters ought therefore to be <i>aerated</i> before being used as
+aliment. Accordingly, at Grenelle, has been constructed a
+tower, from the top of which the water descends in innumerable
+threads, so as to present as much surface as possible to
+the air.</p>
+
+<p>The boring of this Well by the Messrs. Mulot occupied seven
+years, one month, twenty-six days, to the depth of 1794½ English
+feet, or 194½ feet below the depth at which M. Elie de
+Beaumont foretold that water would be found. The sound, or
+borer, weighed 20,000 lb., and was treble the height of that of
+the dome of the Hôpital des Invalides at Paris. In May 1837,
+when the bore had reached 1246 feet 8 inches, the great chisel
+and 262 feet of rods fell to the bottom; and although these
+weighed five tons, M. Mulot tapped a screw on the head of the
+rods, and thus, connecting another length to them, after fifteen
+months’ labour, drew up the chisel. On another occasion, this
+chisel having been raised with great force, sank at one stroke
+85 feet 3 inches into the chalk!</p>
+
+<p><span class="pagenum"><a name="Page_115" id="Page_115">115</a></span></p>
+
+<blockquote>
+
+<p>The depth of the Grenelle Well is nearly four times the height of
+Strasburg Cathedral; more than six times the height of the Hôpital
+des Invalides at Paris; more than four times the height of St. Peter’s
+at Rome; nearly four times and a half the height of St. Paul’s, and nine
+times the height of the Monument, London. Lastly, suppose all the
+above edifices to be piled one upon each other, from the base-line of the
+Well of Grenelle, and they would but reach within 11½ feet of its surface.</p>
+
+<p>MM. Elie de Beaumont and Arago never for a moment doubted the
+final success of the work; their confidence being based on analogy, and
+on a complete acquaintance with the geological structure of the Paris
+basin, which is identical with that of the London basin beneath the
+London clay.</p>
+
+<p>In the duchy of Luxembourg is a well the depth of which surpasses
+all others of the kind. It is upwards of 1000 feet more than that of
+Grenelle near Paris.</p></blockquote>
+
+<h3>HOW THE GULF-STREAM REGULATES THE TEMPERATURE OF
+LONDON.</h3>
+
+<p>Great Britain is almost exactly under the same latitude as
+Labrador, a region of ice and snow. Apparently, the chief
+cause of the remarkable difference between the two climates
+arises from the action of the great oceanic Gulf-Stream, whereby
+this country is kept constantly encircled with waters warmed
+by a West-Indian sun.</p>
+
+<blockquote>
+
+<p>Were it not for this unceasing current from tropical seas, London,
+instead of its present moderate average winter temperature of 6° above
+the freezing-point, might for many months annually be ice-bound by a
+settled cold of 10° to 30° below that point, and have its pleasant summer
+months replaced by a season so short as not to allow corn to ripen, or
+only an alpine vegetation to flourish.</p>
+
+<p>Nor are we without evidence afforded by animal life of a greater
+cold having prevailed in this country at a late geological period. One
+case in particular occurs within eighty miles of London, at the village
+of Chillesford, near Woodbridge, where, in a bed of clayey sand of an
+age but little (geologically speaking) anterior to the London gravel, Mr.
+Prestwich has found a group of fossil shells in greater part identical
+with species now living in the seas of Greenland and of similar latitudes,
+and which must evidently, from their perfect condition and natural
+position, have existed in the place where they are now met with.&mdash;<i>Lectures
+on the Geology of Clapham, &amp;c. by Joseph Prestwich, A.R.S., F.G.S.</i></p></blockquote>
+
+<h3>SOLVENT ACTION OF COMMON SALT AT HIGH TEMPERATURES.</h3>
+
+<p>Forchhammer, after a long series of experiments, has come
+to the conclusion that Common Salt at high temperatures, such
+as prevailed at earlier periods of the earth’s history, acted as
+a general solvent, similarly to water at common temperatures.
+The amount of common salt in the earth would suffice to cover
+its whole surface with a crust ten feet in thickness.</p>
+
+<h3>FREEZING CAVERN IN RUSSIA.</h3>
+
+<p>This famous Cavern, at Ithetz Kaya-Zastchita, in the Steppes<span class="pagenum"><a name="Page_116" id="Page_116">116</a></span>
+of the Kirghis, is employed by the inhabitants as a cellar. It
+has the very remarkable property of being so intensely cold
+during the hottest summers as to be then filled with ice, which
+disappearing with cold weather, is entirely gone in winter, when
+all the country is clad in snow. The roof is hung with ever-dripping
+solid icicles, and the floor may be called a stalagmite
+of ice and frozen earth. “If,” says Sir R. Murchison, “as we
+were assured, <i>the cold is greatest when the external air is hottest
+and driest</i>, that the fall of rain and a moist atmosphere produce
+some diminution of the cold in the cave, and that upon the setting-in
+of winter the ice disappears entirely,&mdash;then indeed the
+problem is very curious.” The peasants assert that in winter
+they could sleep in the cave without their sheepskins.</p>
+
+<h3>INTERIOR TEMPERATURE OF THE EARTH: CENTRAL HEAT.</h3>
+
+<p>By the observed temperature of mines, and that at the bottom
+of artesian wells, it has been established that the rate at
+which such temperature increases as we descend varies considerably
+in different localities, where the depths are comparatively
+small; but where the depths are great, we find a much
+nearer approximation to a common rate of increase, which, as
+determined by the best observation in the deepest mines, shafts,
+and artesian wells in Western Europe, is very nearly 1° F. <i>for
+an increase in depth of fifty feet</i>.&mdash;<i>W. Hopkins, M.A., F.R.S.</i></p>
+
+<p>Humboldt states that, according to tolerably coincident
+experiments in artesian wells, it has been shown that the heat
+increases on an average about 1° for every 54·5 feet. If this
+increase can be reduced to arithmetical relations, it will follow
+that a stratum of granite would be in a state of fusion at a
+depth of nearly twenty-one geographical miles, or between
+four and five times the elevation of the highest summit of the
+Himalaya.</p>
+
+<p>The following is the opinion of Professor Silliman:</p>
+
+<blockquote>
+
+<p>That the whole interior portion of the earth, or at least a great part
+of it, is an ocean of melted rock, agitated by violent winds, though I
+dare not affirm it, is still rendered highly probable by the phenomena
+of volcanoes. The facts connected with their eruption have been ascertained
+and placed beyond a doubt. How, then, are they to be accounted
+for? The theory prevalent some years since, that they are caused by
+the combustion of immense coal-beds, is puerile and now entirely abandoned.
+All the coal in the world could not afford fuel enough for one
+of the tremendous eruptions of Vesuvius.</p></blockquote>
+
+<p>This observed increase of temperature in descending beneath
+the earth’s surface suggested the notion of a central
+incandescent nucleus still remaining in a state of fluidity from
+its elevated temperature. Hence the theory that the whole
+mass of the earth was formerly a molten fluid mass, the exterior
+portion of which, to some unknown depth, has assumed<span class="pagenum"><a name="Page_117" id="Page_117">117</a></span>
+its present solidity by the radiation of heat into surrounding
+space, and its consequent refrigeration.</p>
+
+<p>The mathematical solution of this problem of Central Heat,
+assuming such heat to exist, tells us that though the central
+portion of the earth may consist of a mass of molten matter,
+the temperature of its surface is not thereby increased by more
+than the small fraction of a degree. Poisson has calculated
+that it would require <i>a thousand millions of centuries</i> to reduce
+this fraction to a degree by half its present amount, supposing
+always the external conditions to remain unaltered. In such
+cases, the superficial temperature of the earth may, in fact, be
+considered to have approximated so near to its ultimate limit
+that it can be subject to no further sensible change.</p>
+
+<h3>DISAPPEARANCE OF VOLCANIC ISLANDS.</h3>
+
+<p>Many of the Volcanic Islands thrown up above the sea-level
+soon disappear, because the lavas and conglomerates of which
+they are formed spread over flatter surfaces, through the weight
+of the incumbent fluid; and the constant levelling process goes
+on below the sea by the action of tides and currents. Such
+islands as have effectually resisted this action are found to
+possess a solid framework of lava, supporting or defending the
+loose fragmentary materials.</p>
+
+<blockquote>
+
+<p>Among the most celebrated of these phenomena in our times may be
+mentioned the Isle of Sabrina, which rose off the coast of St. Michael’s
+in 1811, attained a circumference of one mile and a height of 300 feet,
+and disappeared in less than eight months; in the following year there
+were eighty fathoms of water in its place. In July 1831 appeared Graham’s
+Island off the coast of Sicily, which attained a mile in circumference
+and 150 or 160 feet in height; its formation much resembled
+that of Sabrina.</p></blockquote>
+
+<p>The line of ancient subterranean fire which we trace on the
+Mediterranean coasts has had a strange attestation in Graham’s
+Island, which is also described as a volcano suddenly bursting
+forth in the mid sea between Sicily and Africa; burning for
+several weeks, and throwing up an isle, or crater-cone of scoriæ
+and ashes, which had scarcely been named before it was again
+lost by subsidence beneath the sea, leaving only a shoal-bank
+to attest this strange submarine breach in the earth’s crust,
+which thus mingled fire and water in one common action.</p>
+
+<p>Floating islands are not very rare: in 1827, one was seen
+twenty leagues to the east of the Azores; it was three leagues
+in width, and covered with volcanic products, sugar-canes,
+straw, and pieces of wood.</p>
+
+<h3>PERPETUAL FIRE.</h3>
+
+<p>Not far from the Deliktash, on the side of a mountain in
+Lycia, is the Perpetual Fire described some forty years since<span class="pagenum"><a name="Page_118" id="Page_118">118</a></span>
+by Captain Beaufort. It was found by Lieutenant Spratt and
+Professor Forbes, thirty years later, as brilliant as ever, and
+somewhat increased; for besides the large flame in the corner
+of the ruins described by Beaufort, there were small jets issuing
+from crevices in the side of the crater-like cavity five or six feet
+deep. At the bottom was a shallow pool of sulphureous and
+turbid water, regarded by the Turks as a sovereign remedy for
+all skin complaints. The soot deposited from the flames was
+held to be efficacious for sore eyelids, and valued as a dye for
+the eyebrows. This phenomenon is described by Pliny as the
+flame of the Lycian Chimera.</p>
+
+<h3>ARTESIAN FIRE-SPRINGS IN CHINA.</h3>
+
+<p>According to the statement of the missionary Imbert, the
+Fire-Springs, “Ho-tsing” of the Chinese, which are sunk to
+obtain a carburetted-hydrogen gas for salt-boiling, far exceed
+our artesian springs in depth. These springs are very commonly
+more than 2000 feet deep; and a spring of continued
+flow was found to be 3197 feet deep. This natural gas has
+been used in the Chinese province Tse-tschuan for several
+thousand years; and “portable gas” (in bamboo-canes) has for
+ages been used in the city of Khiung-tscheu. More recently,
+in the village of Fredonia, in the United States, such gas has
+been used both for cooking and for illumination.</p>
+
+<h3>VOLCANIC ACTION THE GREAT AGENT OF GEOLOGICAL
+CHANGE.</h3>
+
+<blockquote>
+
+<p>Mr. James Nasmyth observes, that “the floods of molten lava which
+volcanoes eject are nothing less than remaining portions of what was
+once the condition of the entire globe when in the igneous state of its
+early physical history,&mdash;no one knows how many years ago!</p>
+
+<p>“When we behold the glow and feel the heat of molten lava, how
+vastly does it add to the interest of the sight when we consider that the
+heat we feel and the light we see are the residue of the once universal
+condition of our entire globe, on whose <i>cooled surface</i> we <i>now</i> live and
+have our being! But so it is; for if there be one great fact which geological
+research has established beyond all doubt, it is that we reside
+on the cooled surface of what was once a molten globe, and that all the
+phenomena which geology has brought to light can be most satisfactorily
+traced to the successive changes incidental to its gradual cooling
+and contraction.</p>
+
+<p>“That the influx of the sea into the yet hot and molten interior of
+the globe may occasionally occur, and enhance and vary the violence of
+the phenomenon of volcanic action, there can be little doubt; but the
+action of water in such cases is only <i>secondary</i>. But for the pre-existing
+high temperature of the interior of the earth, the influx of water would
+produce no such discharges of molten lava as generally characterise volcanic
+eruptions. Molten lava is therefore a true vestige of the Natural
+History of the Creation.”</p></blockquote>
+
+<p><span class="pagenum"><a name="Page_119" id="Page_119">119</a></span></p>
+
+<h3>THE SNOW-CAPPED VOLCANO.</h3>
+
+<p>It is but rarely that the elastic forces at work within the
+interior of our globe have succeeded in breaking through the
+spiral domes which, resplendent in the brightness of eternal
+snow, crown the summits of the Cordilleras; and even where
+these subterranean forces have opened a permanent communication
+with the atmosphere, through circular craters or long
+fissures, they rarely send forth currents of lava, but merely
+eject ignited scoriæ, steam, sulphuretted hydrogen gas, and
+jets of carbonic acid.&mdash;<i>Humboldt’s Cosmos</i>, vol. i.</p>
+
+<h3>TRAVELS OF VOLCANIC DUST.</h3>
+
+<p>On the 2d of September 1845, a quantity of Volcanic Dust
+fell in the Orkney Islands, which was supposed to have originated
+in an eruption of Hecla, in Iceland. It was subsequently
+ascertained that an eruption of that volcano took place on the
+morning of the above day (September 2), so as to leave no
+doubt of the accuracy of the conclusion. The dust had thus
+travelled about 600 miles!</p>
+
+<h3>GREAT ERUPTIONS OF VESUVIUS.</h3>
+
+<p>In the great eruption of Vesuvius, in August 1779, which
+Sir William Hamilton witnessed from his villa at Pausilippo
+in the bay of Naples, the volcano sent up white sulphureous
+smoke resembling bales of cotton, exceeding the height and
+size of the mountain itself at least four times; and in the midst
+of this vast pile of smoke, stones, scoriæ, and ashes were thrown
+up not less than 2000 feet. Next day a fountain of fire shot
+up with such height and brilliancy that the smallest objects
+could be clearly distinguished at any place within six miles or
+more of Vesuvius. But on the following day a more stupendous
+column of fire rose three times the height of Vesuvius
+(3700 feet), or more than two miles high. Among the huge
+fragments of lava thrown out during this eruption was a block
+108 feet in circumference and 17 feet high, another block
+66 feet in circumference and 19 feet high, and another 16 feet
+high and 92 feet in circumference, besides thousands of smaller
+fragments. Sir William Hamilton suggests that from a scene
+of the above kind the ancient poets took their ideas of the
+giants waging war with Jupiter.</p>
+
+<p>The eruption of June 1794, which destroyed the greater
+part of the town of Torre del Greco, was, however, the most
+violent that has been recorded after the two great eruptions of
+79 and 1631.</p>
+
+<h3>EARTH-WAVES.</h3>
+
+<p>The waves of an earthquake have been represented in their<span class="pagenum"><a name="Page_120" id="Page_120">120</a></span>
+progress, and their propagation, through rocks of different
+density and elasticity; and the causes of the rapidity of propagation,
+and its diminution by the refraction, reflection, and
+interference of the oscillations have been mathematically investigated.
+Air, water, and earth waves follow the same laws
+which are recognised by the theory of motion, at all events in
+space; but the earth-waves are accompanied in their destructive
+action by discharges of elastic vapours, and of gases, and
+mixtures of pyroxene crystals, carbon, and infusorial animalcules
+with silicious shields. The more terrific effects are, however,
+when the earth-waves are accompanied by cleavage; and,
+as in the earthquake of Riobamba, when fissures alternately
+opened and closed again, so that men saved themselves by extending
+both arms, in order to prevent their sinking.</p>
+
+<p>As a remarkable example of the closing of a fissure, Humboldt
+mentions that, during the celebrated earthquake in 1851,
+in the Neapolitan province of Basilicata, a hen was found caught
+by both feet in the street-pavement of Barile, near Melfi.</p>
+
+<p>Mr. Hopkins has very correctly shown theoretically that
+the fissures produced by earthquakes are very instructive as
+regards the formation of veins and the phenomenon of dislocation,
+the more recent vein displacing the older formation.</p>
+
+<h3>RUMBLINGS OF EARTHQUAKES.</h3>
+
+<p>When the great earthquake of Coseguina, in Nicaragua,
+took place, January 23, 1835, the subterranean noise&mdash;the
+sonorous waves in the earth&mdash;was heard at the same time on
+the island of Jamaica and on the plateau of Bogota, 8740 feet
+above the sea, at a greater distance than from Algiers to London.
+In the eruptions of the volcano on the island of St.
+Vincent, April 30, 1812, at 2 <span class="smcap smaller">A.M.</span>, a noise like the report of
+cannons was heard, without any sensible concussion of the earth,
+over a space of 160,000 geographical square miles. There have
+also been heard subterranean thunderings for two years without
+earthquakes.</p>
+
+<h3>HOW TO MEASURE AN EARTHQUAKE-SHOCK.</h3>
+
+<p>A new instrument (the Seismometer) invented for this purpose
+by M. Kreil, of Vienna, consists of a pendulum oscillating
+in every direction, but unable to turn round on its point of
+suspension; and bearing at its extremity a cylinder, which, by
+means of mechanism within it, turns on its vertical axis once
+in twenty-four hours. Next to the pendulum stands a rod bearing
+a narrow elastic arm, which slightly presses the extremity
+of a lead-pencil against the surface of the cylinder. As long as
+the pendulum is quiet, the pencil traces an uninterrupted line<span class="pagenum"><a name="Page_121" id="Page_121">121</a></span>
+on the surface of the cylinder; but as soon as it oscillates, this
+line becomes interrupted and irregular, and these irregularities
+indicate the time of the commencement of an earthquake, together
+with its duration and intensity.<a name="FNanchor_30" id="FNanchor_30" href="#Footnote_30" class="fnanchor">30</a></p>
+
+<p>Elastic fluids are doubtless the cause of the slight and perfectly
+harmless trembling of the earth’s surface, which has often
+continued for several days. The focus of this destructive agent,
+the seat of the moving force, lies far below the earth’s surface;
+but we know as little of the extent of this depth as we know of
+the chemical nature of these vapours that are so highly compressed.
+At the edges of two craters,&mdash;Vesuvius and the towering
+rock which projects beyond the great abyss of Pichincha,
+near Quito,&mdash;Humboldt has felt periodic and very regular shocks
+of earthquakes, on each occasion from twenty to thirty seconds
+before the burning scoriæ or gases were erupted. The intensity
+of the shocks was increased in proportion to the time intervening
+between them, and consequently to the length of time in
+which the vapours were accumulating. This simple fact, which
+has been attested by the evidence of so many travellers, furnishes
+us with a general solution of the phenomenon, in showing that
+active volcanoes are to be considered as safety-valves for the
+immediate neighbourhood. There are instances in which the
+earth has been shaken for many successive days in the chain of
+the Andes, in South America. In certain districts, the inhabitants
+take no more notice of the number of earthquakes than
+we in Europe take of showers of rain; yet in such a district
+Bonpland and Humboldt were compelled to dismount, from the
+restiveness of their mules, because the earth shook in a forest
+for fifteen to eighteen minutes <i>without intermission</i>.</p>
+
+<h3>EARTHQUAKES AND THE MOON.</h3>
+
+<p>From a careful discussion of several thousand earthquakes
+which have been recorded between 1801 and 1850, and a comparison
+of the periods at which they occurred with the position
+of the moon in relation to the earth, M. Perry, of Dijon, infers
+that earthquakes may possibly be the result of attraction exerted
+by that body on the supposed fluid centre of our globe,
+somewhat similar to that which she exercises on the waters of
+the ocean; and the Committee of the Institute of France have
+reported favourably upon this theory.</p>
+
+<h3>THE GREAT EARTHQUAKE OF LISBON.</h3>
+
+<p>The eloquent Humboldt remarks, that the activity of an igneous<span class="pagenum"><a name="Page_122" id="Page_122">122</a></span>
+mountain, however terrific and picturesque the spectacle
+may be which it presents to our contemplation, is always limited
+to a very small space. It is far otherwise with earthquakes,
+which, although scarcely perceptible to the eye, nevertheless
+simultaneously propagate their waves to a distance of many
+thousand miles. The great earthquake which destroyed the
+city of Lisbon, November 1st, 1755, was felt in the Alps, on
+the coast of Sweden, into the Antilles, Antigua, Barbadoes,
+and Martinique; in the great Canadian lakes, in Thuringia, in
+the flat country of northern Germany, and in the small inland
+lakes on the shores of the Baltic. Remote springs were interrupted
+in their flow,&mdash;a phenomenon attending earthquakes
+which had been noticed among the ancients by Demetrius the
+Callatian. The hot springs of Töplitz dried up and returned,
+inundating every thing around, and having their waters coloured
+with iron ochre. At Cadiz, the sea rose to an elevation
+of sixty-four feet; while in the Antilles, where the tide usually
+rises only from twenty-six to twenty-eight inches, it suddenly
+rose about twenty feet, the water being of an inky blackness.
+It has been computed that, on November 1st, 1755, a portion
+of the earth’s surface four times greater than that of Europe
+was simultaneously shaken.<a name="FNanchor_31" id="FNanchor_31" href="#Footnote_31" class="fnanchor">31</a> As yet there is no manifestation
+of force known to us (says the vivid denunciation of the philosopher),
+including even the murderous invention of our own
+race, by which a greater number of people have been killed in
+the short space of a few minutes: 60,000 were destroyed in
+Sicily in 1693, from 30,000 to 40,000 in the earthquake of Riobamba
+in 1797, and probably five times as many in Asia Minor
+and Syria under Tiberius and Justinian the elder, about the
+years 19 and 526.</p>
+
+<h3>GEOLOGICAL AGE OF THE DIAMOND.</h3>
+
+<p>The discovery of Diamonds in Russia, far from the tropical
+zone, has excited much interest among geologists. In the detritus
+on the banks of the Adolfskoi, no fewer than forty diamonds
+have been found in the gold alluvium, only twenty feet
+above the stratum in which the remains of mammoths and rhinoceroses
+are found. Hence Humboldt has concluded that the
+formation of gold-veins, and consequently of diamonds, is comparatively
+of recent date, and scarcely anterior to the destruction
+of the mammoths. Sir Roderick Murchison and M. Verneuil<span class="pagenum"><a name="Page_123" id="Page_123">123</a></span>
+have been led to the same result by different arguments.<a name="FNanchor_32" id="FNanchor_32" href="#Footnote_32" class="fnanchor">32</a></p>
+
+<h3>WHAT WAS ADAMANT?</h3>
+
+<p>Professor Tennant replies, that the Adamant described by
+Pliny was a sapphire, as proved by its form, and by the fact
+that when struck on an anvil by a hammer it would make an
+indentation in the metal. A true diamond, under such circumstances,
+would fly into a thousand pieces.</p>
+
+<h3>WHAT IS COAL?</h3>
+
+<p>The whole evidence we possess as to the nature of Coal
+proves it to have been originally a mass of vegetable matter. Its
+microscopical characters point to its having been formed on the
+spot in which we find it, to its being composed of vegetable
+tissues of various kinds, separated and changed by maceration,
+pressure, and chemical action, and to the introduction of its
+earthy matter, in a large number of instances, in a state of solution
+or fine molecular subdivision. Dr. Redfern, from whose
+communication to the British Association we quote, knows
+nothing to countenance the supposition that our coal-beds are
+mainly formed of coniferous wood, because the structures found
+in mother-coal, or the charcoal layer, have not the character of
+the glandular tissue of such wood, as has been asserted.</p>
+
+<p>Geological research has shown that the immense forests
+from which our coal is formed teemed with life. A frog as
+large as an ox existed in the swamps, and the existence of insects
+proves that the higher order of organic creation flourished
+at this epoch.</p>
+
+<p>It has been calculated that the available coal-beds in Lancashire
+amount in weight to the enormous sum of 8,400,000,000
+tons. The total annual consumption of this coal, it has been
+estimated, amounts to 3,400,120 tons; hence it is inferred that
+the coal-beds of Lancashire, at the present rate of consumption,
+will last 2470 years. Making similar calculations for the coal-fields
+of South Wales, the north of England, and Scotland, it
+will readily be perceived how ridiculous were the forebodings
+which lecturing geologists delighted to indulge in a few years
+ago.</p>
+
+<h3>TORBANE-HILL COAL.</h3>
+
+<p>The coal of Torbane Hill, Scotland, is so highly inflammable,
+that it has been disputed at law whether it be true coal, or
+only asphaltum, or bitumen. Dr. Redfern describes it as laminated,<span class="pagenum"><a name="Page_124" id="Page_124">124</a></span>
+splitting with great ease horizontally, like many cannel
+coals, and like them it may be lighted at a candle. In all parts
+of the bed stigmaria and other fossil plants occur in greater
+numbers than in most other coals; their distinct vascular tissue
+may be easily recognised by a common pocket lens, and 65½ of
+the mass consists of carbon.</p>
+
+<p>Dr. Redfern considers that all our coals may be arranged in
+a scale having the Torbane-Hill coal at the top and anthracite
+at the bottom. Anthracite is almost pure carbon; Torbane Hill
+contains less fixed carbon than most other cannels: anthracite
+is very difficult to ignite, and gives out scarcely any gas; Torbane-Hill
+burns like a candle, and yields 3000 cubic feet of gas
+per ton, more than any other known coal, its gas being also of
+greatly superior illuminating power to any other. The only
+differences which the Torbane-Hill coal presents from others
+are differences of degree, not of kind. It differs from other
+coals in being the best gas-coal, and from other cannels in being
+the best cannel.</p>
+
+<h3>HOW MALACHITE IS FORMED.</h3>
+
+<p>The rich copper-ore of the Ural, which occurs in veins or
+masses, amid metamorphic strata associated with igneous rocks,
+and even in the hollows between the eruptive rocks, is worked
+in shafts. At the bottom of one of these, 280 feet deep, has
+been found an enormous irregularly-shaped botryoidal mass of
+<i>Malachite</i> (Greek <i>malache</i>, mountain-green), sending off strings
+of green copper-ore. The upper surface of it is about 18 feet
+long and 9 wide; and it was estimated to contain 15,000 poods,
+or half a million pounds, of pure and compact malachite. Sir
+Roderick Murchison is of opinion that this wonderful subterraneous
+incrustation has been produced in the stalagmitic
+form, during a series of ages, by copper solutions emanating
+from the surrounding loose and sporous mass, and trickling
+through it to the lowest cavity upon the subjacent solid rock.
+Malachite is brought chiefly from one mine in Siberia; its value
+as raw material is nearly one-fourth that of the same weight of
+pure silver, or in a manufactured state three guineas per pound
+avoirdupois.<a name="FNanchor_33" id="FNanchor_33" href="#Footnote_33" class="fnanchor">33</a></p>
+
+<h3>LUMPS OF GOLD IN SIBERIA.</h3>
+
+<p>The gold mines south of Miask are chiefly remarkable for the
+large lumps or <i>pepites</i> of gold which are found around the Zavod
+of Zarevo-Alexandroisk. Previous to 1841 were discovered<span class="pagenum"><a name="Page_125" id="Page_125">125</a></span>
+here lumps of native gold; in that year a lump of twenty-four
+pounds was met with; and in 1843 a lump weighing about
+seventy-eight pounds English was found, and is now deposited
+with others in the Museum of the Imperial School of Mines at
+St. Petersburg.</p>
+
+<h3>SIR ISAAC NEWTON UPON BURNET’S THEORY OF THE EARTH.</h3>
+
+<p>In 1668, Dr. Thomas Burnet printed his <i>Theoria Telluris
+Sacra</i>, “an eloquent physico-theological romance,” says Sir
+David Brewster, “which was to a certain extent adopted even
+by Newton, Burnet’s friend. Abandoning, as some of the
+fathers had done, the hexaëmeron, or six days of Moses, as a
+physical reality, and having no knowledge of geological phenomena,
+he gives loose reins to his imagination, combining passages
+of Scripture with those of ancient authors, and presumptuously
+describing the future catastrophes to which the earth
+is to be exposed.” Previous to its publication, Burnet presented
+a copy of his book to Newton, and requested his opinion
+of the theory which it propounded. Newton took “exceptions
+to particular passages,” and a correspondence ensued. In one
+of Newton’s letters he treats of the formation of the earth, and
+the other planets, out of a general chaos of the figure assumed
+by the earth,&mdash;of the length of the primitive days,&mdash;of the formation
+of hills and seas, and of the creation of the two ruling
+lights as the result of the clearing up of the atmosphere. He
+considers the account of the creation in Genesis as adapted
+to the judgment of the vulgar. “Had Moses,” he says, “described
+the processes of creation as distinctly as they were in
+themselves, he would have made the narrative tedious and confused
+amongst the vulgar, and become a philosopher more than
+a prophet.” After referring to several “causes of meteors, such
+as the breaking out of vapours from below, before the earth
+was well hardened, the settling and shrinking of the whole
+globe after the upper regions or surface began to be hard,”
+Newton closes his letter with an apology for being tedious,
+which, he says, “he has the more reason to do, as he has not
+set down any thing he has well considered, or will undertake to
+defend.”&mdash;See the Letter in the Appendix to <i>Sir D. Brewster’s
+Life of Newton</i>, vol. ii.</p>
+
+<blockquote>
+
+<p>The primitive condition of the earth, and its preparation for man,
+was a subject of general speculation at the close of the seventeenth century.
+Leibnitz, like his great rival (Newton), attempted to explain the
+formation of the earth, and of the different substances which composed
+it; and he had the advantage of possessing some knowledge of geological
+phenomena: the earth he regarded as having been originally a
+burning mass, whose temperature gradually diminished till the vapours
+were condensed into a universal ocean, which covered the highest mountains,<span class="pagenum"><a name="Page_126" id="Page_126">126</a></span>
+and gradually flowed into vacuities and subterranean cavities produced
+by the consolidation of the earth’s crust. He regarded fossils as
+the real remains of plants and animals which had been buried in the
+strata; and, in speculating on the formation of mineral substances, he
+speaks of crystals as the geometry of inanimate nature.&mdash;<i>Brewster’s Life
+of Newton</i>, vol. ii. p. 100, note. (See also “The Age of the Globe,” in
+<i>Things not generally Known</i>, p. 13.)</p></blockquote>
+
+<h3>“THE FATHER OF ENGLISH GEOLOGY.”</h3>
+
+<p>In 1769 was born, the son of a yeoman of Oxfordshire, William
+Smith. When a boy he delighted to wander in the fields,
+collecting “pound-stones” (<i>Echinites</i>), “pundibs” (<i>Terebratulæ</i>),
+and other stony curiosities; and receiving little education beyond
+what he taught himself, he learned nothing of classics but
+the name. Grown to be a man, he became a land-surveyor and
+civil engineer, and was much engaged in constructing canals.
+While thus occupied, he observed that all the rocky masses
+forming the substrata of the country were gently inclined to
+the east and south-east,&mdash;that the red sandstones and marls
+above the <i>coal-measures</i> passed below the beds provincially
+termed lias-clay and limestone&mdash;that these again passed underneath
+the sands, yellow limestone, and clays that form the
+table-land of the Coteswold Hills; while they in turn plunged
+beneath the great escarpment of chalk that runs from the coast
+of Dorsetshire northward to the Yorkshire shores of the German
+Ocean. He further observed that each formation of clay, sand,
+or limestone, held to a very great extent its own peculiar suite
+of fossils. The “snake-stones” (<i>Ammonites</i>) of the lias were
+different in form and ornament from those of the inferior oolite;
+and the shells of the latter, again, differed from those of the
+Oxford clay, Cornbrash, and Kimmeridge clay. Pondering
+much on these things, he came to the then unheard-of conclusion
+that each formation had been in its turn a sea-bottom,
+in the sediments of which lived and died marine animals now
+extinct, many specially distinctive of their own epochs in time.</p>
+
+<p>Here indeed was a discovery,&mdash;made, too, by a man utterly
+unknown to the scientific world, and having no pretension to
+scientific lore. “Strata Smith’s” find was unheeded for many
+a long year; but at length the first geologists of the day
+learned from the land-surveyor that superposition of strata
+is inseparably connected with the succession of life in time.
+Hooke’s grand vision was at length realised, and it was indeed
+possible “to build up a terrestrial chronology from rotten shells”
+imbedded in the rocks. Meanwhile he had constructed the
+first geological map of England, which has served as a basis for
+geological maps of all other parts of the world. William Smith
+was now presented by the Geological Society with the Wollaston
+Medal, and hailed as “the Father of English Geology.”<span class="pagenum"><a name="Page_127" id="Page_127">127</a></span>
+He died in 1840. Till the manner as well as the fact of the first
+appearance of successive forms of life shall be solved, it is not
+easy to surmise how any discovery can be made in geology
+equal in value to that which we owe to the genius of William
+Smith.&mdash;<i>Saturday Review</i>, No. 140.</p>
+
+<h3>DR. BUCKLAND’s GEOLOGICAL LABOURS.</h3>
+
+<p>Sir Henry De la Beche, in his Anniversary Address to the
+Geological Society in 1848, on presenting the Wollaston Medal
+to Dr. Buckland, felicitously observed:</p>
+
+<blockquote>
+
+<p>It may not be generally known that, while yet a child, at your
+native town, Axminster in Devonshire, ammonites, obtained by your
+father from the lime quarries in the neighbourhood, were presented to
+your attention. As a scholar at Winchester, the chalk, with its flints,
+was brought under your observation, and there it was that your collections
+in natural history first began. Removed to Oxford, as a scholar
+of Corpus Christi College, the future teacher of geology in that University
+was fortunate in meeting with congenial tastes in our colleague
+Mr. W.&nbsp;J. Broderip, then a student at Oriel College. It was during your
+walks together to Shotover Hill, when his knowledge of conchology was
+so valuable to you, enabling you to distinguish the shells of the Oxford
+oolite, that you laid the foundation for those field-lectures, forming part
+of your course of geology at Oxford, which no one is likely to forget who
+has been so fortunate at any time as to have attended them. The fruits
+of your walks with Mr. Broderip formed the nucleus of that great collection,
+more especially remarkable for the organic remains it contains,
+which, after the labours of forty years, you have presented to the Geological
+Museum at Oxford, in grave recollection of the aid which the
+endowments of that University, and the leisure of its vacations, had
+afforded you for extensive travelling during a residence at Oxford of
+nearly forty-five years.</p></blockquote>
+
+<h3 title="Discoveries of M. Agassiz.">DISCOVERIES OF M. AGASSIZ.<a name="FNanchor_34" id="FNanchor_34" href="#Footnote_34" class="fnanchor smaller">34</a></h3>
+
+<p>This great paleontologist, in the course of his ichthyological
+researches, was led to perceive that the arrangement by Cuvier
+according to organs did not fulfil its purpose with regard to
+fossil fishes, because in the lapse of ages the characteristics of
+their structures were destroyed. He therefore adopted the only
+other remaining plan, and studied the tissues, which, being
+less complex than the organs, are oftener found intact. The
+result was the very remarkable discovery, that the tegumentary
+membrane of fishes is so intimately connected with their organisation,
+that if the whole of the fish has perished except this
+membrane, it is practicable, by noting its characteristics, to reconstruct
+the animal in its most essential parts. Of the value
+of this principle of harmony, some idea may be formed from
+the circumstance, that on it Agassiz has based the whole of that<span class="pagenum"><a name="Page_128" id="Page_128">128</a></span>
+celebrated classification of which he is the sole author, and by
+which fossil ichthyology has for the first time assumed a precise
+and definite shape. How essential its study is to the geologist
+appears from the remark of Sir Roderick Murchison, that “fossil
+fishes have every where proved the most exact chronometer
+of the age of rocks.”</p>
+
+<h3>SUCCESSION OF LIFE IN TIME.</h3>
+
+<p>In the Museum of Economic Geology, in Jermyn Street, may
+be seen ores, metals, rocks, and whole suites of fossils stratigraphically
+arranged in such a manner that, with an observant
+eye for form, all may easily understand the more obvious scientific
+meanings of the Succession of Life in Time, and its bearing
+on geological economies. It is perhaps scarcely an exaggeration
+to say, that the greater number of so-called educated persons
+are still ignorant of the meaning of this great doctrine. They
+would be ashamed not to know that there are many suns and
+material worlds besides our own; but the science, equally grand
+and comprehensible, that aims at the discovery of the laws that
+regulated the creation, extension, decadence, and utter extinction
+of many successive species, genera, and whole orders of life,
+is ignored, or, if intruded on the attention, is looked on as an
+uncertain and dangerous dream,&mdash;and this in a country which
+was almost the nursery of geology, and which for half a century
+has boasted the first Geological Society in the world.&mdash;<i>Saturday
+Review</i>, No. 140.</p>
+
+<h3>PRIMITIVE DIVERSITY AND NUMBERS OF ANIMALS IN
+GEOLOGICAL TIMES.</h3>
+
+<p>Professor Agassiz considers that the very fact of certain stratified
+rocks, even among the oldest formations, being almost
+entirely made up of fragments of organised beings, should long
+ago have satisfied the most sceptical that both <i>animal and
+vegetable life were as active and profusely scattered upon the whole
+globe at all times, and during all geological periods, as they are
+now</i>. No coral reef in the Pacific contains a larger amount
+of organic <i>débris</i> than some of the limestone deposits of the
+tertiary, of the cretaceous, or of the oolitic, nay even of the
+paleozoic period; and the whole vegetable carpet covering the
+present surface of the globe, even if we were to consider only
+the luxuriant vegetation of the tropics, leaving entirely out of
+consideration the entire expanse of the ocean, as well as those
+tracts of land where, under less favourable circumstances, the
+growth of plants is more reduced,&mdash;would not form one single
+seam of workable coal to be compared to the many thick beds
+contained in the rocks of the carboniferous period alone.</p>
+
+<p><span class="pagenum"><a name="Page_129" id="Page_129">129</a></span></p>
+
+<h3>ENGLAND IN THE EOCENE PERIOD.</h3>
+
+<p>Eocene is Sir Charles Lyell’s term for the lowest group of
+the Tertiary system in which the dawn of recent life appears;
+and any one who wishes to realise what was the aspect presented
+by this country during the Eocene period, need only go
+to Sheerness. If, leaving that place behind him, he walks
+down the Thames, keeping close to the edge of the water, he
+will find whole bushels of pyritised pieces of twigs and fruits.
+These fruits and twigs belong to plants nearly allied to the
+screw-pine and custard-apple, and to various species of palms
+and spice-trees which now flourish in the Eastern Archipelago.
+At the time they were washed down from some neighbouring
+land, not only crocodilian reptiles, but sharks and innumerable
+turtles, inhabited a sea or estuary which now forms part of the
+London district; and huge boa-constrictors glided amongst the
+trees which fringed the adjoining shores.</p>
+
+<p>Countless as are the ages which intervened between the
+Eocene period and the time when the little jawbones of Stonesfield
+were washed down to the place where they were to await
+the day when science should bring them again to light, not one
+mammalian genus which now lives upon our plane has been
+discovered amongst Eocene strata. We have existing families,
+but nothing more.&mdash;<i>Professor Owen.</i></p>
+
+<h3>FOOD OF THE IGUANODON.</h3>
+
+<p>Dr. Mantell, from the examination of the anterior part of
+the right side of the lower jaw of an Iguanodon discovered in a
+quarry in Tilgate Forest, Sussex, has detected an extraordinary
+deviation from all known types of reptilian organisation, and
+which could not have been predicated; namely, that this colossal
+reptile, which equalled in bulk the gigantic Edentata of
+South America, and like them was destined to obtain support
+from comminuted vegetable substances, was also furnished with a
+large prehensile tongue and fleshy lips, to serve as instruments
+for seizing and cropping the foliage and branches of trees;
+while the arrangement of the teeth as in the ruminants, and
+their internal structure, which resembles that of the molars of
+the sloth tribe in the vascularity of the dentine, indicate adaptations
+for the same purpose.</p>
+
+<p>Among the physiological phenomena revealed by paleontology,
+there is not a more remarkable one than this modification
+of the type of organisation peculiar to the class of reptiles to
+meet the conditions required by the economy of a lizard placed
+under similar physical relations; and destined to effect the
+same general purpose in the scheme of nature as the colossal<span class="pagenum"><a name="Page_130" id="Page_130">130</a></span>
+Edentata of former ages and the large herbivorous mammalia
+of our own times.</p>
+
+<h3>THE PTERODACTYL&mdash;THE FLYING DRAGON.</h3>
+
+<p>The Tilgate beds of the Wealden series, just mentioned, have
+yielded numerous fragments of the most remarkable reptilian
+fossils yet discovered, and whose wonderful forms denote them
+to have thronged the shallow seas and bays and lagoons of the
+period. In the grounds of the Crystal Palace at Sydenham
+the reader will find restorations of these animals sufficiently
+perfect to illustrate this reptilian epoch. They include the <i>iguanodon</i>,
+an herbivorous lizard exceeding in size the largest elephant,
+and accompanied by the equally gigantic and carnivorous
+<i>megalosaurus</i> (great saurian), and by the two yet more
+curious reptiles, the <i>pylæosaurus</i> (forest, or weald, saurian) and
+the pterodactyl (from <i>pteron</i>, ‘wing,’ and <i>dactylus</i>, ‘a finger’),
+an enormous bat-like creature, now running upon the ground
+like a bird; its elevated body and long neck not covered with
+feathers, but with skin, naked, or resplendent with glittering
+scales; its head like that of a lizard or crocodile, and of a size
+almost preposterous compared with that of the body, with its
+long fore extremities stretched out, and connected by a membrane
+with the body and hind legs.</p>
+
+<p>Suddenly this mailed creature rose in the air, and realised
+or even surpassed in strangeness <i>the flying dragon of fable</i>: its
+fore-arms and its elongated wing-finger furnished with claws;
+hand and fingers extended, and the interspace filled up by a
+tough membrane; and its head and neck stretched out like
+that of the heron in its flight. When stationary, its wings
+were probably folded back like those of a bird; though perhaps,
+by the claws attached to its fingers, it might suspend itself from
+the branches of trees.</p>
+
+<h3>MAMMALIA IN SECONDARY ROCKS.</h3>
+
+<p>It was supposed till very lately that few if any Mammalia
+were to be found below the Tertiary rocks, <i>i. e.</i> those above the
+chalk; and this supposed fact was very comfortable to those
+who support the doctrine of “progressive development,” and
+hold, with the notorious <i>Vestiges of Creation</i>, that a fish by
+mere length of time became a reptile, a lemur an ape, and
+finally an ape a man. But here, as in a hundred other cases,
+facts, when duly investigated, are against their theory. A
+mammal jaw had been already discovered by Mr. Brodie on
+the shore at the back of Swanage Point, in Dorsetshire, when
+Mr. Beckles, F.G.S., traced the vein from which this jaw had
+been procured, and found it to be a stratum about five inches<span class="pagenum"><a name="Page_131" id="Page_131">131</a></span>
+thick, at the base of the Middle Purbeck beds; and after removing
+many thousand tons of rock, and laying bare an area of
+nearly 7000 square feet (the largest cutting ever made for purely
+scientific purposes), he found reptiles (tortoises and lizards) in
+hundreds; but the most important discovery was that of the
+jaws of at least fourteen different species of mammalia. Some
+of these were herbivorous, some carnivorous, connected with
+our modern shrews, moles, hedgehogs, &amp;c.; but all of them perfectly
+developed and highly-organised quadrupeds. Ten years
+ago, no remains of quadrupeds were believed to exist in the
+Secondary strata. “Even in 1854,” says Sir Charles Lyell (in
+a supplement to the fifth edition of his <i>Manual of Elementary
+Geology</i>), “only six species of mammals from rocks older than
+the Tertiary were known in the whole world.” We now possess
+evidence of the existence of fourteen species, belonging to eight
+or nine genera, from the fresh-water strata of the Middle Purbeck
+Oolite. It would be rash now to fix a limit in past time
+to the existence of quadrupeds.&mdash;<i>The Rev. C. Kingsley.</i></p>
+
+<h3>FOSSIL HUMAN BONES.</h3>
+
+<p>In the paleontological collection in the British Museum is
+preserved a considerable portion of a human skeleton imbedded
+in a slab of rock, brought from Guadaloupe, and often referred
+to in opposition to the statement that hitherto <i>no fossil human
+hones have been found</i>. The presence of these bones, however,
+has been explained by the circumstance of a battle and the
+massacre of a tribe of Galtibis by the Caribs, which took place
+near the spot in which the bones were found about 130 years
+ago; for as the bodies of the slain were interred on the seashore,
+their skeletons may have been subsequently covered by
+sand-drift, which has since consolidated into limestone.</p>
+
+<p>It will be seen by reference to the <i>Philosophical Transactions</i>,
+that on the reading of the paper upon this discovery to
+the Royal Society, in 1814, Sir Joseph Banks, the president,
+considered the “fossil” to be of very modern formation, and
+that probably, from the contiguity of a volcano, the temperature
+of the water may have been raised at some time, and dissolving
+carbonate of lime readily, may have deposited about
+the skeleton in a comparatively short period hard and solid
+stone. Every person may be convinced of the rapidity of the
+formation and of the hardness of such stone by inspecting the
+inside of tea-kettles in which hard water is boiled.</p>
+
+<blockquote>
+
+<p>Descriptions of petrifactions of human bodies appear to refer to the
+conversion of bodies into adipocere, and not into stone. All the supposed
+cases of petrifaction are probably of this nature. The change
+occurs only when the coffin becomes filled with water. The body, converted
+into adipocere, floats on the water. The supposed cases of<span class="pagenum"><a name="Page_132" id="Page_132">132</a></span>
+changes of position in the grave, bursting open the coffin-lids, turning
+over, crossing of limbs, &amp;c., formerly attributed to the coming to life of
+persons buried who were not dead, is now ascertained to be due to the
+same cause. The chemical change into adipocere, and the evolution of
+gases, produce these movements of dead bodies.&mdash;<i>Mr. Trail Green.</i></p></blockquote>
+
+<h3>THE MOST ANCIENT FISHES.</h3>
+
+<p>Among the important results of Sir Roderick Murchison’s
+establishment of the Silurian system is the following:</p>
+
+<blockquote>
+
+<p>That as the Lower Silurian group, often of vast dimensions, has
+never afforded the smallest vestige of a Fish, though it abounds in numerous
+species of the <i>marine</i> classes,&mdash;corals, <i>crinoidea</i>, <i>mollusca</i>, and
+<i>crustacea</i>; and as in Scandinavia and Russia, where it is based on rocks
+void of fossils, its lowest stratum contains <i>fucoids</i> only,&mdash;Sir R. Murchison
+has, after fifteen years of laborious research steadily directed to
+this point, arrived at the conclusion, that a very long period elapsed
+after life was breathed into the waters before the lowest order of vertebrata
+was created; the earliest fishes being those of the Upper Silurian
+rocks, which he was the first to discover, and which he described “as
+the most ancient beings of their class which have yet been brought to
+light.” Though the Lower Silurian rocks of various parts of the world
+have since been ransacked by multitudes of prying geologists, who have
+exhumed from them myriads of marine fossils, not a single ichthyolite
+has been found in any stratum of higher antiquity than the Upper
+Silurian group of Murchison.</p></blockquote>
+
+<p>The most remarkable of all fossil fishes yet discovered have
+been found in the Old Red Sandstone cliffs at Dorpat, where
+the remains are so gigantic (one bone measuring <i>two feet nine
+inches</i> in length) that they were at first supposed to belong to
+saurians.</p>
+
+<p>Sir Roderick’s examination of Russia has, in short, proved
+that <i>the ichthyolites and mollusks which, in Western Europe, are
+separately peculiar to smaller detached basins, were here (in the
+British Isles) cohabitants of many parts of the same great sea</i>.</p>
+
+<h3>EXTINCT CARNIVOROUS ANIMALS OF BRITAIN.</h3>
+
+<p>Professor Owen has thus forcibly illustrated the Carnivorous
+Animals which preyed upon and restrained the undue multiplication
+of the vegetable feeders. First we have the bear
+family, which is now represented in this country only by the
+badger. We were once blest, however, with many bears. One
+species seems to have been identical with the existing brown
+bear of the European continent. Far larger and more formidable
+was the gigantic cave-bear (<i>Ursus spelæus</i>), which surpassed in
+size his grisly brother of North America. The skull of the cave-bear
+differs very much in shape from that of its small brown
+relative just alluded to; the forehead, in particular, is much
+higher,&mdash;to be accounted for by an arrangement of air-cells similar
+to those which we have already remarked in the elephant.<span class="pagenum"><a name="Page_133" id="Page_133">133</a></span>
+The cave-bear has left its remains in vast abundance in Germany.
+In our own caves, the bones of hyænas are found in
+greater quantities. The marks which the teeth of the hyæna
+make upon the bones which it gnaws are quite unmistakable.
+Our English hyænas had the most undiscriminating appetite,
+preying upon every creature, their own species amongst others.
+Wolves, not distinguishable from those which now exist in
+France and Germany, seem to have kept company with the
+hyænas; and the <i>Felis spelæa</i>, a sort of lion, but larger than
+any which now exists, ruled over all weaker brutes. Here,
+says Professor Owen, we have the original British Lion. A
+species of <i>Machairodus</i> has left its remains at Kent’s Hole, near
+Torquay. In England we had also the beaver, which still
+lingers on the Danube and the Rhone, and a larger species,
+which has been called Trogontherium (gnawing beast), and a
+gigantic mole.</p>
+
+<h3>THE GREAT CAVE TIGER OR LION OF BRITAIN.</h3>
+
+<p>Remains of this remarkable animal of the drift or gravel
+period of this country have been found at Brentford and elsewhere
+near London. Speaking of this animal, Professor Owen
+observes, that “it is commonly supposed that the Lion, the
+Tiger, and the Jaguar are animals peculiarly adapted to a
+tropical climate. The genus Felis (to which these animals
+belong) is, however, represented by specimens in high northern
+latitudes, and in all the intermediate countries to the equator.”
+The chief condition necessary for the presence of such animals
+is an abundance of the vegetable-feeding animals. It is thus
+that the Indian tiger has been known to follow the herds of
+antelope and deer in the lofty mountains of the Himalaya to the
+verge of perpetual snow, and far into Siberia. “It need not,
+therefore,” continues Professor Owen, “excite surprise that
+indications should have been discovered in the fossil relics of
+the ancient mammalian population of Europe of a large feline
+animal, the contemporary of the mammoth, of the tichorrhine
+rhinoceros, of the great gigantic cave-bear and hyæna, and the
+slayer of the oxen, deer, and equine quadrupeds that so
+abounded during the same epoch.” The dimensions of this
+extinct animal equal those of the largest African lion or Bengal
+tiger; and some bones have been found which seem to imply
+that it had even more powerful limbs and larger paws.</p>
+
+<h3>THE MAMMOTHS OF THE BRITISH ISLES.</h3>
+
+<p>Dr. Buckland has shown that for long ages many species
+of carnivorous animals now extinct inhabited the caves of the
+British islands. In low tracts of Yorkshire, where tranquil
+lacustrine (lake-like) deposits have occurred, bones (even those<span class="pagenum"><a name="Page_134" id="Page_134">134</a></span>
+of the lion) have been found so perfectly unbroken and unworn,
+in fine gravel (as at Market Weighton), that few persons
+would be disposed to deny that such feline and other animals
+once roamed over the British isles, as well as other European
+countries. Why, then, is it improbable that large elephants,
+with a peculiarly thick integument, a close coating of wool,
+and much long shaggy hair, should have been the occupants
+of wide tracts of Northern Europe and Asia? This coating,
+Dr. Fleming has well remarked, was probably as impenetrable
+to rain and cold as that of the monster ox of the polar circle.
+Such is the opinion of Sir Roderick Murchison, who thus accounts
+for the disappearance of the mammoths from Britain:</p>
+
+<blockquote>
+
+<p>When we turn from the great Siberian continent, which, anterior to
+its elevation, was the chief abode of the mammoths, and look to the
+other parts of Europe, where their remains also occur, how remarkable
+is it that we find the number of these creatures to be justly proportionate
+to the magnitude of the ancient masses of land which the labours
+of geologists have defined! Take the British isles, for example, and let
+all their low, recently elevated districts be submerged; let, in short,
+England be viewed as the comparatively small island she was when the
+ancient estuary of the Thames, including the plains of Hyde Park,
+Chelsea, Hounslow, and Uxbridge, were under the water; when the
+Severn extended far into the heart of the kingdom, and large eastern
+tracts of the island were submerged,&mdash;and there will then remain but
+moderately-sized feeding-grounds for the great quadrupeds whose bones
+are found in the gravel of the adjacent rivers and estuaries.</p></blockquote>
+
+<p>This limited area of subsistence could necessarily only keep
+up a small stock of such animals; and, just as we might expect,
+the remains of British mammoths occur in very small
+numbers indeed, when compared with those of the great charnel-houses
+of Siberia, into which their bones had been carried
+down through countless ages from the largest mass of surface
+which geological inquiries have yet shown to have been <i>dry
+land</i> during that epoch.</p>
+
+<p>The remains of the mammoth, says Professor Owen, have
+been found in all, or almost all, the counties of England. Off
+the coast of Norfolk they are met with in vast abundance.
+The fishermen who go to catch turbot between the mouth of
+the Thames and the Dutch coast constantly get their nets entangled
+in the tusks of the mammoth. A collection of tusks
+and other remains, obtained in this way, is to be seen at Ramsgate.
+In North America, this gigantic extinct elephant must
+have been very common; and a large portion of the ivory
+which supplies the markets of Europe is derived from the vast
+mammoth graveyards of Siberia.</p>
+
+<p>The mammoth ranged at least as far north as 60°. There
+is no doubt that, at the present day, many specimens of the
+musk-ox are annually becoming imbedded in the mud and ice
+of the North-American rivers.</p>
+
+<p><span class="pagenum"><a name="Page_135" id="Page_135">135</a></span>
+It is curious to observe, that the mammoth teeth which are
+met with in caves generally belonged to young mammoths, who
+probably resorted thither for shelter before increasing age and
+strength emboldened them to wander far afield.</p>
+
+<h3>THE RHINOCEROS AND HIPPOPOTAMUS OF ENGLAND.</h3>
+
+<p>The mammoth was not the only giant that inhabited England
+in the Pliocene or Upper Tertiary period. We had also
+here the <i>Rhinoceros tichorrhinus</i>, or “strongly walled about the
+nose,” remains of which have been discovered in enormous
+quantities in the brickfields about London. Pallas describes
+an entire specimen of this creature, which was found near
+Yakutsk, the coldest town on the globe. Another rhinoceros,
+<i>leptorrhinus</i> (fine nose), dwelt with the elephant of Southern
+Europe. In Siberia has been discovered the Elaimotherium,
+forming a link between the rhinoceros and the horse.</p>
+
+<p>In the days of the mammoth, we had also in England a
+Hippopotamus, rather larger than the species which now inhabits
+the Nile. Of our British hippopotamus some remains
+were dug up by the workmen in preparing the foundations of
+the New Junior United Service Club-house, in Regent-street.</p>
+
+<h3>THE ELEPHANT AND TORTOISE.</h3>
+
+<p>The idea of an Elephant standing on the back of a Tortoise
+was often laughed at as an absurdity, until Captain Cautley
+and Dr. Falconer at length discovered in the hills of Asia the
+remains of a tortoise in a fossil state of such a size that an
+elephant could easily have performed the above feat.</p>
+
+<h3>COEXISTENCE OF MAN AND THE MASTODON.</h3>
+
+<p>Dr. C. F. Winslow has communicated to the Boston Society
+of Natural History the discovery of the fragment of a human
+cranium 180 feet below the surface of the Table Mountain,
+California. Now the mastodon’s bones being found in the
+same deposits, points very clearly to the probability of the appearance
+of the human race on the western portions of North
+America at least before the extinction of those huge creatures.
+Fragments of mastodon and <i>Elephas primigenius</i> have been
+taken ten and twenty feet below the surface in the above locality;
+where this discovery of human and mastodon remains
+gives strength to the possible truth of an old Indian tradition,&mdash;the
+contemporary existence of the mammoth and aboriginals
+in this region of the globe.</p>
+
+<h3>HABITS OF THE MEGATHERIUM.</h3>
+
+<p>Much uncertainty has been felt about the habits of the Megatherium,
+or Great Beast. It has been asked whether it burrowed<span class="pagenum"><a name="Page_136" id="Page_136">136</a></span>
+or climbed, or what it did; and difficulties have presented
+themselves on all sides of the question. Some have
+thought that it lived in trees as much larger than those which
+now exist as the Megatherium itself is larger than the common
+sloth.<a name="FNanchor_35" id="FNanchor_35" href="#Footnote_35" class="fnanchor">35</a> This, however, is now known to be a mistake. It did
+not climb trees&mdash;it pulled them down; and in order to do this
+the hinder parts of its skeleton were made enormously strong,
+and its prehensile fore-legs formed so as to give it a tremendous
+power over any thing which it grasped. Dr. Buckland suggested
+that animals which got their living in this way had
+a very fair chance of having their heads broken. While Professor
+Owen was still pondering over this difficulty, the skull
+of a cognate animal, the Mylodon, came into his hands. Great
+was his delight when he found that the mylodon not only had
+his head broken, but broken in two different places, at two
+different times; and moreover so broken that the injury could
+only have been inflicted by some such agent as a fallen tree.
+The creature had recovered from the first blow, but had evidently
+died of the second. This tribe had, as it turns out,
+two skulls, an outer and an inner one&mdash;given them, as it
+would appear, expressly with a view to the very dangerous
+method in which they were intended to obtain their necessary
+food.</p>
+
+<p>The dentition of the megatherium is curious. The elephant
+gets teeth as he wants them. Nature provided for the
+comfort of the megatherium in another way. It did not get
+new teeth, but the old ones went on for ever growing as long
+as the animal lived; so that as fast as one grinding surface became
+useless, another supplied its place.</p>
+
+<h3>THE DINOTHERIUM, OR TERRIBLE BEAST.</h3>
+
+<p>The family of herbivorous Cetaceans are connected with the
+Pachydermata of the land by one of the most wonderful of all
+the extinct creatures with which geologists have made us acquainted.
+This is the <i>Dinotherium</i>, or Terrible Beast. The remains
+of this animal were found in Miocene sands at Eppelsheim,
+about forty miles from Darmstadt. It must have been
+larger than the largest extinct or living elephant. The most
+remarkable peculiarity of its structure is the enormous tusks,
+curving downwards and terminating its lower jaw. It appears
+to have lived in the water, where the immense weight of these
+formidable appendages would not be so inconvenient as on
+land. What these tusks were used for is a mystery; but perhaps
+they acted as pickaxes in digging up trees and shrubs, or as<span class="pagenum"><a name="Page_137" id="Page_137">137</a></span>
+harrows in raking the bottom of the water. Dr. Buckland used
+to suggest that they were perhaps employed as anchors, by
+means of which the monster might fasten itself to the bank of
+a stream and enjoy a comfortable nap. The extreme length of
+the <i>Dinotherium</i> was about eighteen feet. Professor Kemp, in
+his restoration of the animal, has given it a trunk like that of
+the elephant, but not so long, and the general form of the tapir.&mdash;<i>Professor
+Owen.</i></p>
+
+<h3>THE GLYPTODON.</h3>
+
+<p>There are few creatures which we should less have expected
+to find represented in fossil history by a race of gigantic brethren
+than the armadillo. The creature is so small, not only in size
+but in all its works and ways, that we with difficulty associate
+it with the idea of magnitude. Yet Sir Woodbine Parish has
+discovered evidences of enormous animals of this family having
+once dwelt in South America. The huge loricated (plated over)
+creature whose relics were first sent has received the name of
+Glyptodon, from its sculptured teeth. Unlike the small armadillos,
+it was unable to roll itself up into a ball; though an
+enormous carnivore which lived in those days must have made
+it sometimes wish it had the power to do so. When attacked,
+it must have crouched down, and endeavoured to make its huge
+shell as good a defence as possible.&mdash;<i>Professor Owen.</i></p>
+
+<h3>INMATES OF AN AUSTRALIAN CAVERN.</h3>
+
+<p>From the fossil-bone caverns in Wellington Valley, in 1830,
+were sent to Professor Owen several bones which belonged, as
+it turned out, to gigantic kangaroos, immensely larger than
+any existing species; to a kind of wombat, to formidable dasyures,
+and several other genera. It also appeared that the
+bones, which were those of herbivores, had evidently belonged
+to young animals, while those of the carnivores were full-sized;
+a fact which points to the relations between the two families
+having been any thing but agreeable to the herbivores.</p>
+
+<h3>THE POUCH-LION OF AUSTRALIA.</h3>
+
+<p>The <i>Thylacoleo</i> (Pouch-Lion) was a gigantic marsupial carnivore,
+whose character and affinities Professor Owen has, with
+exquisite scientific tact, made out from very small indications.
+This monster, which had kangaroos with heads three feet long
+to feed on, must have been one of the most extraordinary animals
+of the antique world.</p>
+
+<h3>THE CONEY OF SCRIPTURE.</h3>
+
+<p>Paleontologists have pointed out the curious fact that the<span class="pagenum"><a name="Page_138" id="Page_138">138</a></span>
+Hyrax, called ‘coney’ in our authorised version of the Bible, is
+really only a diminutive and hornless rhinoceros. Remains have
+been found at Eppelsheim which indicate an animal more like a
+gigantic Hyrax than any of the existing rhinoceroses. To this
+the name of <i>Acerotherium</i> (Hornless Beast) has been given.</p>
+
+<h3>A THREE-HOOFED HORSE.</h3>
+
+<p>Professor Owen describes the <i>Hipparion</i>, or Three-hoofed
+Horse, as the first representative of a family so useful to mankind.
+This animal, in addition to its true hoof, appears to
+have had two additional elementary hoofs, analogous to those
+which we see in the ox. The object of these no doubt was to
+enable the Hipparion to extricate his foot with greater ease
+than he otherwise could when it sank through the swampy
+ground on which he lived.</p>
+
+<h3>TWO MONSTER CARNIVORES OF FRANCE.</h3>
+
+<p>A huge carnivorous creature has been found in Miocene
+strata in France, in which country it preyed upon the gazelle
+and antelope. It must have been as large as a grisly bear, but
+in general appearance and teeth more like a gigantic dog.
+Hence the name of <i>Amphicyon</i> (Doubtful Dog) has been assigned
+to it. This animal must have derived part of its support
+from vegetables. Not so the coeval monster which has been
+called <i>Machairodus</i> (Sabre-tooth). It must have been somewhat
+akin to the tiger, and is by far the most formidable animal
+which we have met with in our ascending progress through
+the extinct mammalia.&mdash;<i>Professor Owen.</i></p>
+
+<h3>GEOLOGY OF THE SHEEP.</h3>
+
+<p>No unequivocal fossil remains of the sheep have yet been
+found in the bone-caves, the drift, or the more tranquil stratified
+newer Pliocene deposits, so associated with the fossil bones
+of oxen, wild-boars, wolves, foxes, otters, &amp;c., as to indicate
+the coevality of the sheep with those species, or in such an
+altered state as to indicate them to have been of equal antiquity.
+Professor Owen had his attention particularly directed
+to this point in collecting evidence for a history of British
+Fossil Mammalia. No fossil core-horns of the sheep have yet
+been any where discovered; and so far as this negative evidence
+goes, we may infer that the sheep is not geologically
+more ancient than man; that it is not a native of Europe, but
+has been introduced by the tribes who carried hither the germs
+of civilisation in their migrations westward from Asia.</p>
+
+<h3>THE TRILOBITE.</h3>
+
+<p>Among the earliest races we have those remarkable forms,<span class="pagenum"><a name="Page_139" id="Page_139">139</a></span>
+the Trilobites, inhabiting the ancient ocean. These crustacea
+remotely resemble the common wood-louse, and like that animal
+they had the power of rolling themselves into a ball when
+attacked by an enemy. The eye of the trilobite is a most remarkable
+organ; and in that of one species, <i>Phacops caudatus</i>,
+not less than 250 lenses have been discovered. This remarkable
+optical instrument indicates that these creatures lived
+under similar conditions to those which surround the crustacea
+of the present day.&mdash;<i>Hunt’s Poetry of Science.</i></p>
+
+<h3>PROFITABLE SCIENCE.</h3>
+
+<p>In that strip of reddish colour which runs along the cliffs
+of Suffolk, and is called the Redcrag, immense quantities of
+cetacean remains have been found. Four different kinds of
+whales, little inferior in size to the whalebone whale, have left
+their bones in this vast charnel-house. In 1840, a singularly
+perplexing fossil was brought to Professor Owen from this Redcrag.
+No one could say what it was. He determined it to be
+the tooth of a cetacean, a unique specimen. Now the remains
+of cetaceans in the Suffolk crag have been discovered in such
+enormous quantities, that many thousands a-year are made by
+converting them into manure.</p>
+
+<h3>EXTINCT GIGANTIC BIRDS OF NEW ZEALAND.</h3>
+
+<p>In the islands of New Zealand have been found the bones of
+large extinct wingless Birds, belonging to the Post Tertiary or
+Recent system, which have been deposited by the action of rivers.
+The bird is named <i>Moa</i> by the natives, and <i>Dinornis</i> by naturalists:
+some of the bones have been found in two caves in the
+North Island, and have been sold by the natives at an extraordinary
+price. The caves occur in limestone rocks, and the bones
+are found beneath earth and a soft deposit of carbonate of lime.
+The largest of the birds is stated to have stood thirteen or fourteen
+feet, or twice the height of the ostrich; and its egg large
+enough to fill the hat of a man as a cup. Several statements
+have appeared of these birds being still in existence, but there
+is every reason to believe the Moa to be altogether extinct.</p>
+
+<p>An extensive collection of remains of these great wingless
+birds has been collected in New Zealand by Mr. Walter Mantell,
+and deposited in the British Museum. Among these bones
+Professor Owen has discovered a species which he regards as
+the most remarkable of the feathered class for its prodigious
+strength and massive proportions, and which he names <i>Dinornis
+elephantopus</i>, or elephant-footed, of which the Professor has
+been able to construct an entire lower limb: the length of the
+metatarsal bone is 9¼ inches, the breadth of the lower end<span class="pagenum"><a name="Page_140" id="Page_140">140</a></span>
+being 5-1/3 inches. The extraordinary proportions of the metatarsus
+of this wingless bird will, however, be still better understood
+by comparison with the same bone in the ostrich, in
+which the metatarsus is 19 inches in length, the breadth of its
+lower end being only 2½ inches. From the materials accumulated
+by Mr. Mantell, the entire skeleton of the <i>Dinornis elephantopus</i>
+has been reconstructed; and now forms a worthy
+companion of the Megatherium and Mastodon in the gallery of
+fossil remains in the British Museum. This species of <i>Dinornis</i>
+appears to have been restricted to the Middle Island of New
+Zealand.<a name="FNanchor_36" id="FNanchor_36" href="#Footnote_36" class="fnanchor">36</a></p>
+
+<p>Another specimen of the remains of the <i>Dinornis</i> is preserved
+in the Museum of the Royal College of Surgeons, in
+Lincoln’s-Inn Fields; and the means by which the college
+obtained this valuable acquisition is thus graphically narrated
+by Mr. Samuel Warren, F.R.S.:</p>
+
+<blockquote>
+
+<p>In the year 1839, Professor Owen was sitting alone in his study, when
+a shabbily-dressed man made his appearance, announcing that he had
+got a great curiosity, which he had brought from New Zealand, and
+wished to dispose of to him. It had the appearance of an old marrow-bone,
+about six inches in length, and rather more than two inches
+in thickness, <i>with both extremities broken off</i>; and Professor Owen considered
+that, to whatever animal it might have belonged, the fragment
+must have lain in the earth for centuries. At first he considered this
+same marrow-bone to have belonged to an ox, at all events to a quadruped;
+for the wall or rim of the bone was six times as thick as the bone
+of any bird, even of the ostrich. He compared it with the bones in the
+skeleton of an ox, a horse, a camel, a tapir, and every quadruped apparently
+possessing a bone of that size and configuration; but it corresponded
+with none. On this he very narrowly examined the surface of
+the bony rim, and at length became satisfied that this fragment must
+have belonged to <i>a bird</i>!&mdash;to one at least as large as an ostrich, but of
+a totally different species; and consequently one never before heard of,
+as an ostrich was by far the biggest bird known.</p>
+
+<p>From the difference in the <i>strength</i> of the bone, the ostrich being unable
+to fly, so must have been unable this unknown bird; and so our
+anatomist came to the conclusion that this old shapeless bone indicated
+the former existence in New Zealand of some huge bird, at least as
+great as an ostrich, but of a far heavier and more sluggish kind. Professor
+Owen was confident of the validity of his conclusions, but would
+communicate that confidence to no one else; and notwithstanding attempts
+to dissuade him from committing his views to the public, he
+printed his deductions in the <i>Transactions of the Zoological Society for
+1839</i>, where fortunately they remain on record as conclusive evidence of
+the fact of his having then made this guess, so to speak, in the dark.
+He caused the bone, however, to be engraved; and having sent a hundred<span class="pagenum"><a name="Page_141" id="Page_141">141</a></span>
+copies of the engraving to New Zealand, in the hope of their being
+distributed and leading to interesting results, he patiently waited for
+three years,&mdash;viz. till the year 1842,&mdash;when he received intelligence
+from Dr. Buckland, at Oxford, that a great box, just arrived from New
+Zealand, consigned to himself, was on its way, unopened, to Professor
+Owen, who found it filled with bones, palpably of a bird, one of which
+bones was three feet in length, and much more than double the size of
+any bone in the ostrich!</p>
+
+<p>And out of the contents of this box the Professor was positively enabled
+to articulate almost the entire skeleton of a huge wingless bird
+between <span class="smcap smaller">TEN</span> and <span class="smcap smaller">ELEVEN</span> feet in height, its bony structure in strict conformity
+with the fragment in question; and that skeleton may at any
+time be seen at the Museum of the College of Surgeons, towering over,
+and nearly twice the height of, the skeleton of an ostrich; and at its feet
+lying the old bone from which alone consummate anatomical science had
+deduced such an astounding reality,&mdash;the existence of an enormous extinct
+creature of the bird kind, in an island where previously no bird
+had been known to exist larger than a pheasant or a common fowl!&mdash;<i>Lecture
+on the Moral and Intellectual Development of the present Age.</i><a name="FNanchor_37" id="FNanchor_37" href="#Footnote_37" class="fnanchor">37</a></p></blockquote>
+
+<h3>“THE MAESTRICHT SAURIAN FOSSIL” A FRAUD.</h3>
+
+<p>In 1795, there was stated to have been discovered in the
+stone quarries adjoining Maestricht the remains of the gigantic
+<i>Mosœsaurus</i> (Saurian of the Meuse), an aquatic reptile about
+twenty-five feet long, holding an intermediate place between
+the Monitors and Iguanas. It appears to have had webbed feet,
+and a tail of such construction as to have served for a powerful
+oar, and enabled the animal to stem the waves of the ocean, of
+which Cuvier supposed it to have been an inhabitant. It is
+thus referred to by Dr. Mantell, in his <i>Medals of Creation</i>: “A
+specimen, with the jaws and bones of the palate, now in the
+Museum at Paris, has long been celebrated; and is still the most
+precious relic of this extinct reptile hitherto discovered.” An
+admirable cast of this specimen is preserved in the British Museum,
+in a case near the bones of the Iguanodon. This is, however,
+useless, as Cuvier is proved to have been imposed upon in
+the matter.</p>
+
+<blockquote>
+
+<p>M. Schlegel has reported to the French Academy of Sciences, that
+he has ascertained beyond all doubt that the famous fossil saurian of
+the quarries of Maestricht, described as a wonderful curiosity by Cuvier,
+is nothing more than an impudent fraud. Some bold impostor, it seems,
+in order to make money, placed a quantity of bones in the quarries in
+such a way as to give them the appearance of having been recently dug
+up, and then passed them off as specimens of antediluvian creation.
+Being successful in this, he went the length of arranging a number of
+bones so as to represent an entire skeleton; and had thus deceived the<span class="pagenum"><a name="Page_142" id="Page_142">142</a></span>
+learned Cuvier. In extenuation of Cuvier’s credulity, it is stated that
+the bones were so skilfully coloured as to make them look of immense
+antiquity, and he was not allowed to touch them lest they should crumble
+to pieces. But when M. Schlegel subjected them to rude handling, he
+found that they were comparatively modern, and that they were placed
+one by the other without that profound knowledge of anatomy which
+was to have been expected from the man bold enough to execute such
+an audacious fraud.</p></blockquote>
+
+<h3>“THE OLDEST PIECE OF WOOD UPON EARTH.”</h3>
+
+<p>The most remarkable vegetable relic which the Lower Old
+Red Sandstone has given us is a small fragment of a coniferous
+tree of the Araucarian family, which formed one of the chief
+ornaments of the late Hugh Miller’s museum, and to which he
+used to point as the oldest piece of wood upon earth. He found
+it in one of the ichthyolite beds of Cromarty, and thus refers to
+it in his <i>Testimony of the Rocks</i>:</p>
+
+<blockquote>
+
+<p>On what perished land of the early paleozoic ages did this venerably
+antique tree cast root and flourish, when the extinct genera Pterichthys
+and Coccoeteus were enjoying life by millions in the surrounding seas,
+long ere the flora or fauna of the coal measures had begun to be?</p>
+
+<p>The same nodule which enclosed this lignite contained part of another
+fossil, the well-marked scales of <i>Diplacanthus striatus</i>, an ichthyolite restricted
+to the Lower Old Red Sandstone exclusively. If there be any
+value in paleontological evidence, this Cromarty lignite must have been
+deposited in a sea inhabited by the Coccoeteus and Diplacanthus. It
+is demonstrable that, while yet in a recent state, a Diplacanthus lay down
+and died beside it; and the evidence in the case is unequivocally this,
+that in the oldest portion of the oldest terrestrial flora yet known there
+occurs the fragment of a tree quite as high in the scale as the stately
+Norfolk-Island pine or the noble cedar of Lebanon.</p></blockquote>
+
+<h3>NO FOSSIL ROSE.</h3>
+
+<p>Professor Agassiz, in a lecture upon the trees of America,
+states a remarkable fact in regard to the family of the rose,&mdash;which
+includes among its varieties not only many of the
+most beautiful flowers, but also the richest fruits, as the apple,
+pear, peach, plum, apricot, cherry, strawberry, raspberry, &amp;c.,&mdash;namely,
+that <i>no fossil plants belonging to this family have ever
+been discovered by geologists</i>! This M. Agassiz regards as conclusive
+evidence that the introduction of this family of plants
+upon the earth was coeval with, or subsequent to, the creation
+of man, to whose comfort and happiness they seem especially
+designed by a wise Providence to contribute.</p>
+
+<h3>CHANGES ON THE EARTH’S SURFACE.</h3>
+
+<p>In the Imperial Library at Paris is preserved a manuscript
+work by an Arabian writer, Mohammed Karurini, who flourished
+in the seventh century of the Hegira, or at the close of the
+thirteenth century of our era. Herein we find several curious<span class="pagenum"><a name="Page_143" id="Page_143">143</a></span>
+remarks on aerolites and earthquakes, and the successive
+changes of position which the land and sea have undergone.
+Of the latter class is the following beautiful passage from the
+narrative of Khidz, an allegorical personage:</p>
+
+<blockquote>
+
+<p>I passed one day by a very ancient and wonderfully populous city,
+and asked one of its inhabitants how long it had been founded. “It is
+indeed a mighty city,” replied he; “we know not how long it has existed,
+and our ancestors were on this subject as ignorant as ourselves.”
+Five centuries afterwards, as I passed by the same place, I could not
+perceive the slightest vestige of the city. I demanded of a peasant who
+was gathering herbs upon its former site how long it had been destroyed.
+“In sooth, a strange question,” replied he; “the ground here has never
+been different from what you now behold it.” “Was there not of old,”
+said I, “a splendid city here?” “Never,” answered he, “so far as we
+have seen; and never did our fathers speak to us of any such.” On my
+return there five hundred years afterwards, <i>I found the sea in the same
+place</i>; and on its shores were a party of fishermen, of whom I inquired
+how long the land had been covered by the waters. “Is this a question,”
+say they, “for a man like you? This spot has always been what it is
+now.” I again returned five hundred years afterwards; the sea had
+disappeared: I inquired of a man who stood alone upon the spot how
+long this change had taken place, and he gave me the same answer as
+I had received before. Lastly, on coming back again after an equal
+lapse of time, I found there a flourishing city, more populous and more
+rich in beautiful buildings than the city I had seen the first time; and
+when I would fain have informed myself concerning its origin, the inhabitants
+answered me, “Its rise is lost in remote antiquity: we are
+ignorant how long it has existed, and our fathers were on this subject
+as ignorant as ourselves.”</p></blockquote>
+
+<p class="in0">This striking passage was quoted in the <i>Examiner</i>, in 1834.
+Surely in this fragment of antiquity we trace the “geological
+changes” of modern science.</p>
+
+<h3>GEOLOGICAL TIME.</h3>
+
+<p>Many ingenious calculations have been made to approximate
+the dates of certain geological events; but these, it must
+be confessed, are more amusing than instructive. For example,
+so many inches of silt are yearly laid down in the delta of the
+Mississippi&mdash;how many centuries will it have taken to accumulate
+a thickness of 30, 60, or 100 feet? Again, the ledges
+of Niagara are wasting at the rate of so many feet per century&mdash;how
+many years must the river have taken to cut its way
+back from Queenstown to the present Falls? Again, lavas
+and melted basalts cool, according to the size of the mass, at
+the rate of so many degrees in a given time&mdash;how many millions
+of years must have elapsed, supposing an original igneous
+condition of the earth, before its crust had attained a state of
+solidity? or further, before its surface had cooled down to the
+present mean temperature? For these and similar computations,
+the student will at once perceive we want the necessary<span class="pagenum"><a name="Page_144" id="Page_144">144</a></span>
+uniformity of factor; and until we can bring elements of calculation
+as exact as those of astronomy to bear on geological
+chronology, it will be better to regard our “eras” and “epochs”
+and “systems” as so many terms, indefinite in their duration,
+but sufficient for the magnitude of the operations embraced
+within their limits.&mdash;<i>Advanced Textbook of Geology, by David
+Page, F.G.S.</i></p>
+
+<p>M. Rozet, in 1841, called attention to the fact, that the
+causes which have produced irregularities in the structure of
+the globe have not yet ceased to act, as is proved by earthquakes,
+volcanic eruptions, slow and continuous movements
+of the crust of the earth in certain regions, &amp;c. We may,
+therefore, yet see repeated the great catastrophes which the
+surface of the earth has undergone anteriorly to the historical
+period.</p>
+
+<p>At the meeting of the British Association in 1855, Mr. Hopkins
+excited much controversy by his startling speculation&mdash;that
+9000 years ago the site on which London now stands was
+in the torrid zone; and that, according to perpetual changes
+in progress, the whole of England would in time arrive within
+the Arctic circle.</p>
+
+<h3>CURIOUS CAUSE OF CHANGE OF LEVEL.</h3>
+
+<p>Professor Hennessey, in 1857, <i>found the entire mass of rock
+and hill on which the Armagh Observatory is erected to be slightly,
+but to an astronomer quite perceptibly, tilted or canted, at one season
+to the east, at another to the west</i>. This he at first attributed to
+the varying power of the sun’s radiation to heat and expand
+the rock throughout the year; but he subsequently had reason
+to attribute it rather to the infiltration of water to the parts
+where the clay-slate and limestone rocks met, the varying
+quantity of the water exerting a powerful hydrostatic energy
+by which the position of the rock is slightly varied.</p>
+
+<p>Now Armagh and its observatory stand at the junction of
+the mountain limestone with the clay-slate, having, as it were,
+one leg on the former and the other on the latter; and both
+rocks probably reach downwards 1000 or 2000 feet. When
+rain falls, the one will absorb more water than the other; both
+will gain an increase of conductive power; but the one which
+has absorbed most water will have the greatest increase, and
+being thus the better conductor, will <i>draw a greater portion of
+heat from the hot nucleus below to the surface</i>&mdash;will become, in
+fact, temporarily hotter, and, as a consequence, <i>expand more
+than the other</i>. In a word, <i>both rocks will expand at the wet
+season; but the best conductor, or most absorbent rock, will expand
+most, and seem to tilt the hill to one side; at the dry season it will<span class="pagenum"><a name="Page_145" id="Page_145">145</a></span>
+subside most, and the hill will seem to be tilted in the opposite direction</i>.</p>
+
+<p>The fact is curious, and not less so are the results deducible
+from it. First, hills are higher at one season than another;
+a fact we might have supposed, but never could have ascertained
+by measurement. Secondly, they are highest, not, as we
+should have supposed, at the hottest season, but at the wettest.
+Thirdly, it is from the <i>different rates</i> of expansion of different
+rocks that this has been discovered. Fourthly, it is by converse
+with the <i>heavens</i> that it has been made known to us. A variation
+of probably half a second, or less, in the right ascension
+of three or four stars, observed at different seasons, no doubt
+revealed the fact to the sagacious astronomer of Armagh, and
+even enabled him to divine its cause.</p>
+
+<blockquote>
+
+<p>Professor Hennessey observes in connection with this phenomenon,
+that a very small change of ellipticity would suffice to lay bare or submerge
+extensive tracts of the globe. If, for example, the mean ellipticity
+of the ocean increased from 1/300 to 1/299, the level of the sea would
+be raised at the equator by about 228 feet, while under the parallel of
+52° it would be depressed by 196 feet. Shallow seas and banks in the
+latitudes of the British isles, and between them and the pole, would
+thus be converted into dry land, while low-lying plains and islands near
+the equator would be submerged. If similar phenomena occurred during
+early periods of geological history, they would manifestly influence the
+distribution of land and water during these periods; and with such a
+direction of the forces as that referred to, they would tend to increase
+the proportion of land in the polar and temperate regions of the earth,
+as compared with the equatorial regions during successive geological
+epochs. Such maps as those published by Sir Charles Lyell on the distribution
+of land and water in Europe during the Tertiary period, and
+those of M. Elie de Beaumont, contained in Beaudant’s <i>Geology</i>, would,
+if sufficiently extended, assist in verifying or disproving these views.</p></blockquote>
+
+<h3>THE OUTLINES OF CONTINENTS NOT FIXED.</h3>
+
+<p>Continents (says M. Agassiz) are only a patchwork formed
+by the emergence and subsidence of land. These processes are
+still going on in various parts of the globe. Where the shores
+of the continent are abrupt and high, the effect produced may
+be slight, as in Norway and Sweden, where a gradual elevation
+is going on without much alteration in their outlines. But if
+the continent of North America were to be depressed 1000 feet,
+nothing would remain of it except a few islands, and any elevation
+would add vast tracts to its shores.</p>
+
+<p>The west of Asia, comprising Palestine and the country
+about Ararat and the Caspian Sea, is below the level of the
+ocean, and a rent in the mountain-chains by which it is surrounded
+would transform it into a vast gulf.</p>
+
+<hr />
+
+<p><span class="pagenum"><a name="Page_146" id="Page_146">146</a></span></p>
+
+<div class="chapter"></div>
+<h2><a name="Meteorological" id="Meteorological"></a>Meteorological Phenomena.</h2>
+
+<h3>THE ATMOSPHERE.</h3>
+
+<p>A philosopher of the East, with a richness of imagery truly
+oriental, describes the Atmosphere as “a spherical shell which
+surrounds our planet to a depth which is unknown to us, by
+reason of its growing tenuity, as it is released from the pressure
+of its own superincumbent mass. Its upper surface cannot
+be nearer to us than 50, and can scarcely be more remote
+than 500, miles. It surrounds us on all sides, yet we see it not;
+it presses on us with a load of fifteen pounds on every square
+inch of surface of our bodies, or from seventy to one hundred
+tons on us in all, yet we do not so much as feel its weight.
+Softer than the softest down, more impalpable than the finest
+gossamer, it leaves the cobweb undisturbed, and scarcely stirs
+the lightest flower that feeds on the dew it supplies; yet it
+bears the fleets of nations on its wings around the world, and
+crushes the most refractory substances with its weight. When
+in motion, its force is sufficient to level the most stately forests
+and stable buildings with the earth&mdash;to raise the waters of the
+ocean into ridges like mountains, and dash the strongest ships
+to pieces like toys. It warms and cools by turns the earth and
+the living creatures that inhabit it. It draws up vapours from
+the sea and land, retains them dissolved in itself or suspended
+in cisterns of clouds, and throws them down again as rain or
+dew when they are required. It bends the rays of the sun
+from their path to give us the twilight of evening and of dawn;
+it disperses and refracts their various tints to beautify the approach
+and the retreat of the orb of day. But for the atmosphere
+sunshine would burst on us and fail us at once, and at once
+remove us from midnight darkness to the blaze of noon. We
+should have no twilight to soften and beautify the landscape;
+no clouds to shade us from the searching heat; but the bald
+earth, as it revolved on its axis, would turn its tanned and
+weakened front to the full and unmitigated rays of the lord of
+day. It affords the gas which vivifies and warms our frames,
+and receives into itself that which has been polluted by use
+and is thrown off as noxious. It feeds the flames of life exactly
+as it does that of the fire&mdash;it is in both cases consumed and
+affords the food of consumption&mdash;in both cases it becomes
+combined with charcoal, which requires it for combustion and
+is removed by it when this is over.”</p>
+
+<p><span class="pagenum"><a name="Page_147" id="Page_147">147</a></span></p>
+
+<h3>UNIVERSALITY OF THE ATMOSPHERE.</h3>
+
+<p>It is only the girdling, encircling air that flows above and
+around all that makes the whole world kin. The carbonic acid
+with which to-day our breathing fills the air, to-morrow makes
+its way round the world. The date-trees that grow round the
+falls of the Nile will drink it in by their leaves; the cedars of
+Lebanon will take of it to add to their stature; the cocoa-nuts
+of Tahiti will grow rapidly upon it; and the palms and bananas
+of Japan will change it into flowers. The oxygen we are
+breathing was distilled for us some short time ago by the magnolias
+of the Susquehanna; the great trees that skirt the Orinoco
+and the Amazon, the giant rhododendrons of the Himalayas,
+contributed to it, and the roses and myrtles of Cashmere,
+the cinnamon-tree of Ceylon, and the forest, older than the
+Flood, buried deep in the heart of Africa, far behind the Mountains
+of the Moon. The rain we see descending was thawed
+for us out of the icebergs which have watched the polar star
+for ages; and the lotus-lilies have soaked up from the Nile, and
+exhaled as vapour, snows that rested on the summits of the
+Alps.&mdash;<i>North-British Review.</i></p>
+
+<h3>THE HEIGHT OF THE ATMOSPHERE.</h3>
+
+<p>The differences existing between that which appertains to
+the air of heaven (the realms of universal space) and that which
+belongs to the strata of our terrestrial atmosphere are very
+striking. It is not possible, as well-attested facts prove, perfectly
+to explain the operations at work in the much-contested
+upper boundaries of our atmosphere. The extraordinary lightness
+of whole nights in the year 1831, during which small print
+might be read at midnight in the latitudes of Italy and the north
+of Germany, is a fact directly at variance with all we know
+according to the researches on the crepuscular theory and the
+height of the atmosphere. The phenomena of light depend
+upon conditions still less understood; and their variability at
+twilight, as well as in the zodiacal light, excite our astonishment.
+Yet the atmosphere which surrounds the earth is not
+thicker in proportion to the bulk of our globe than the line of
+a circle two inches in diameter when compared with the space
+which it encloses, or the down on the skin of a peach in comparison
+with the fruit inside.</p>
+
+<h3>COLOURS OF THE ATMOSPHERE.</h3>
+
+<p>Pure air is blue, because, according to Newton, the molecules
+of the air have the thickness necessary to reflect blue rays.
+When the sky is not perfectly pure, and the atmosphere is
+blended with perceptible vapours, the diffused light is mixed<span class="pagenum"><a name="Page_148" id="Page_148">148</a></span>
+with a large proportion of white. As the moon is yellow, the
+blue of the air assumes somewhat of a greenish tinge, or, in
+other words, becomes blended with yellow.&mdash;<i>Letter from Arago
+to Humboldt</i>; <i>Cosmos</i>, vol. iii.</p>
+
+<h3>BEAUTY OF TWILIGHT.</h3>
+
+<p>This phenomenon is caused by the refraction of solar light
+enabling it to diffuse itself gradually over our hemisphere, obscured
+by the shades of night, long before the sun appears, even
+when that luminary is eighteen degrees below our horizon. It
+is towards the poles that this reflected splendour of the great
+luminary is longest visible, often changing the whole of the
+night into a magic day, of which the inhabitants of southern
+Europe can form no adequate conception.</p>
+
+<h3>HOW PASCAL WEIGHED THE ATMOSPHERE.</h3>
+
+<p>Pascal’s treatise on the weight of the whole mass of air
+forms the basis of the modern science of Pneumatics. In order
+to prove that the mass of air presses by its weight on all the
+bodies which it surrounds, and also that it is elastic and compressible,
+he carried a balloon, half-filled with air, to the top
+of the Puy de Dome, a mountain about 500 toises above Clermont,
+in Auvergne. It gradually inflated itself as it ascended,
+and when it reached the summit it was quite full, and swollen
+as if fresh air had been blown into it; or, what is the same
+thing, it swelled in proportion as the weight of the column of
+air which pressed upon it was diminished. When again brought
+down it became more and more flaccid, and when it reached
+the bottom it resumed its original condition. In the nine
+chapters of which the treatise consists, Pascal shows that all
+the phenomena and effects hitherto ascribed to the horror of a
+vacuum arise from the weight of the mass of air; and after explaining
+the variable pressure of the atmosphere in different
+localities and in its different states, and the rise of water in
+pumps, he calculates that the whole mass of air round our globe
+weighs 8,983,889,440,000,000,000 French pounds.&mdash;<i>North-British
+Review</i>, No. 2.</p>
+
+<p>It seems probable, from many indications, that the greatest
+height at which visible clouds <i>ever exist</i> does not exceed ten
+miles; at which height the density of the air is about an eighth
+part of what it is at the level of the sea.&mdash;<i>Sir John Herschel.</i></p>
+
+<h3>VARIATIONS OF CLIMATE.</h3>
+
+<p>History informs us that many of the countries of Europe
+which now possess very mild winters, at one time experienced
+severe cold during this season of the year. The Tiber, at Rome,
+was often frozen over, and snow at one time lay for forty days<span class="pagenum"><a name="Page_149" id="Page_149">149</a></span>
+in that city. The Euxine Sea was frozen over every winter
+during the time of Ovid, and the rivers Rhine and Rhone used
+to be frozen over so deep that the ice sustained loaded wagons.
+The waters of the Tiber, Rhine, and Rhone, now flow freely
+every winter; ice is unknown in Rome, and the waves of the
+Euxine dash their wintry foam uncrystallised upon the rocks.
+Some have ascribed these climate changes to agriculture&mdash;the
+cutting down of dense forests, the exposing of the unturned soil
+to the summer’s sun, and the draining of great marshes. We
+do not believe that such great changes could be produced on
+the climate of any country by agriculture; and we are certain
+that no such theory can account for the contrary change of climate&mdash;from
+warm to cold winters&mdash;which history tells us has
+taken place in other countries than those named. Greenland
+received its name from the emerald herbage which once clothed
+its valleys and mountains; and its east coast, which is now inaccessible
+on account of perpetual ice heaped upon its shores,
+was in the eleventh century the seat of flourishing Scandinavian
+colonies, all trace of which is now lost. Cold Labrador was
+named Vinland by the Northmen, who visited it <span class="smcap smaller">A.D.</span> 1000, and
+were charmed with its then mild climate. The cause of these
+changes is an important inquiry.&mdash;<i>Scientific American.</i></p>
+
+<h3>AVERAGE CLIMATES.</h3>
+
+<p>When we consider the numerous and rapid changes which
+take place in our climate, it is a remarkable fact, that <i>the mean
+temperature of a place remains nearly the same</i>. The winter may
+be unusually cold, or the summer unusually hot, while the
+mean temperature has varied even less than a degree. A very
+warm summer is therefore likely to be accompanied with a
+cold winter; and in general, if we have any long period of
+cold weather, we may expect a similar period at a higher temperature.
+In general, however, in the same locality the relative
+distribution over summer and winter undergoes comparatively
+small variations; therefore every point of the globe has
+an average climate, though it is occasionally disturbed by different
+atmospheric changes.&mdash;<i>North-British Review</i>, No. 49.</p>
+
+<h3>THE FINEST CLIMATE IN THE WORLD.</h3>
+
+<p>Humboldt regards the climate of the Caspian Sea as the
+most salubrious in the world: here he found the most delicious
+fruits that he saw during his travels; and such was the purity
+of the air, that polished steel would not tarnish even by night
+exposure.</p>
+
+<p><span class="pagenum"><a name="Page_150" id="Page_150">150</a></span></p>
+
+<h3>THE PUREST ATMOSPHERES.</h3>
+
+<p>The cloudless purity and transparency of the atmosphere,
+which last for eight months at Santiago, in Chili, are so great,
+that Lieutenant Gilliss, with the first telescope ever constructed
+in America, having a diameter of seven inches, was clearly able
+to recognise the sixth star in the trapezium of Orion. If we
+are to rely upon the statements of the Rev. Mr. Stoddart, an
+American missionary, Oroomiah, in Persia, seems to be, in so
+far as regards the transparency of the atmosphere, the most
+suitable place in the world for an astronomical observatory.
+Writing to Sir John Herschel from that country, he mentions
+that he has been enabled to distinguish with the naked eye the
+satellites of Jupiter, the crescent of Venus, the rings of Saturn,
+and the constituent members of several double stars.</p>
+
+<h3>SEA-BREEZES AND LAND-BREEZES ILLUSTRATED.</h3>
+
+<p>When a fire is kindled on the hearth, we may, if we will
+observe the motes floating in the room, see that those nearest
+the chimney are the first to feel the draught and to obey it,&mdash;they
+are drawn into the blaze. The circle of inflowing air is
+gradually enlarged, until it is scarcely perceived in the remote
+parts of the room. Now the land is the hearth, the rays of the
+sun the fire, and the sea, with its cool and calm air, the room;
+and thus we have at our firesides the sea-breeze in miniature.</p>
+
+<p>When the sun goes down, the fire ceases; then the dry land
+commences to give off its surplus heat by radiation, so that by
+nine or ten o’clock it and the air above it are cooled below the
+sea temperature. The atmosphere on the land thus becomes
+heavier than that on the sea, and consequently there is a wind
+seaward, which we call the land-breeze.&mdash;<i>Maury.</i></p>
+
+<h3>SUPERIOR SALUBRITY OF THE WEST.</h3>
+
+<p>All large cities and towns have their best districts in the
+West;<a name="FNanchor_38" id="FNanchor_38" href="#Footnote_38" class="fnanchor">38</a> which choice the French <i>savans</i>, Pelouze, Pouillet,
+Boussingault, and Elie de Beaumont, attribute to the law of
+atmospheric pressure. “When,” say they, “the barometric
+column rises, smoke and pernicious emanations rapidly evaporate
+in space.” On the contrary, smoke and noxious vapours remain<span class="pagenum"><a name="Page_151" id="Page_151">151</a></span>
+in apartments, and on the surface of the soil. Now,
+of all winds, that which causes the greatest ascension of the
+barometric column is the east; and that which lowers it most
+is the west. When the latter blows, it carries with it to the
+eastern parts of the town all the deleterious gases from the
+west; and thus the inhabitants of the east have to support
+their own smoke and miasma, and those brought by western
+winds. When, on the contrary, the east wind blows, it purifies
+the air by causing to ascend the pernicious emanations which it
+cannot drive to the west. Consequently, the inhabitants of the
+west receive pure air, from whatever part of the horizon it may
+arrive; and as the west winds are most prevalent, they are the
+first to receive the air pure, and as it arrives from the country.</p>
+
+<h3>FERTILISATION OF CLOUDS.</h3>
+
+<p>As the navigator cruises in the Pacific Ocean among the
+islands of the trade-wind region, he sees gorgeous piles of cumuli,
+heaped up in fleecy masses, not only capping the island
+hills, but often overhanging the lowest islet of the tropics, and
+even standing above coral patches and hidden reefs; “a cloud
+by day.” to serve as a beacon to the lonely mariner out there at
+sea, and to warn him of shoals and dangers which no lead nor
+seaman’s eye has ever seen or sounded. These clouds, under
+favourable circumstances, may be seen gathering above the low
+coral island, preparing it for vegetation and fruitfulness in a
+very striking manner. As they are condensed into showers,
+one fancies that they are a sponge of the most exquisite and delicately
+elaborated material, and that he can see, as they “drop
+down their fatness,” the invisible but bountiful hand aloft that
+is pressing and squeezing it out.&mdash;<i>Maury.</i></p>
+
+<h3>BAROMETRIC MEASUREMENT.</h3>
+
+<p>We must not place too implicit a dependence on Barometrical
+Measurements. Ermann in Siberia, and Ross in the Antarctic
+Seas, have demonstrated the existence of localities on the
+earth’s surface where a permanent depression of the barometer
+prevails to the astonishing extent of nearly an inch.</p>
+
+<h3>GIGANTIC BAROMETER.</h3>
+
+<p>In the Great Exhibition Building of 1851 was a colossal
+Barometer, the tube and scale reaching from the floor of the
+gallery nearly to the top of the building, and the rise and fall
+of the indicating fluid being marked by feet instead of by tenths
+of inches. The column of mercury, supported by the pressure
+of the atmosphere, communicated with a perpendicular tube of<span class="pagenum"><a name="Page_152" id="Page_152">152</a></span>
+smaller bore, which contained a coloured fluid much lighter
+than mercury. When a diminution of atmospheric pressure occurred,
+the mercury in the large tube descended, and by its fall
+forced up the coloured fluid in the smaller tube; the fall of the
+one being indicated in a magnified ratio by the rise in the other.</p>
+
+<h3>THE ATMOSPHERE COMPARED TO A STEAM-ENGINE.</h3>
+
+<p>In this comparison, by Lieut. Maury, the South Seas themselves,
+in all their vast intertropical extent, are the boiler for
+the engine, and the northern hemisphere is its condenser. The
+mechanical power exerted by the air and the sun in lifting
+water from the earth, in transporting it from one place to another,
+and in letting it down again, is inconceivably great.
+The utilitarian who compares the water-power that the Falls
+of Niagara would afford if applied to machinery is astonished
+at the number of figures which are required to express its equivalent
+in horse-power. Yet what is the horse-power of the Niagara,
+falling a few steps, in comparison with the horse-power
+that is required to lift up as high as the clouds and let down
+again all the water that is discharged into the sea, not only by
+this river, but by all the other rivers in the world? The calculation
+has been made by engineers; and according to it, the
+force of making and lifting vapour from each area of one acre
+that is included on the surface of the earth, is equal to the
+power of thirty horses; and for the whole of the earth, it is 800
+times greater than all the water-power in Europe.</p>
+
+<h3>HOW DOES THE RAIN-MAKING VAPOUR GET FROM THE
+SOUTHERN INTO THE NORTHERN HEMISPHERE?</h3>
+
+<p>This comes with such regularity, that our rivers never go
+dry, and our springs fail not, because of the exact <i>compensation</i>
+of the grand machine of <i>the atmosphere</i>. It is exquisitely
+and wonderfully counterpoised. Late in the autumn of the
+north, throughout its winter, and in early spring, the sun is
+pouring his rays with the greatest intensity down upon the
+seas of the southern hemisphere; and this powerful engine,
+which we are contemplating, is pumping up the water there
+with the greatest activity; at the same time, the mean temperature
+of the entire southern hemisphere is about 10° higher
+than the northern. The heat which this heavy evaporation
+absorbs becomes latent, and with the moisture is carried
+through the upper regions of the atmosphere until it reaches
+our climates. Here the vapour is formed into clouds, condensed
+and precipitated; the heat which held their water in the
+state of vapour is set free, and becomes sensible heat; and it is
+that which contributes so much to temper our winter climate.<span class="pagenum"><a name="Page_153" id="Page_153">153</a></span>
+It clouds up in winter, turns warm, and we say we are going
+to have falling weather: that is because the process of condensation
+has already commenced, though no rain or snow may
+have fallen. Thus we feel this southern heat, that has been collected
+by the rays of the sun by the sea, been bottled away by
+the winds in the clouds of a southern summer, and set free in
+the process of condensation in our northern winter.</p>
+
+<p>Thus the South Seas should supply mainly the water for
+the engine just described, while the northern hemisphere condenses
+it; we should, therefore, have more rain in the northern
+hemisphere. The rivers tell us that we have, at least on
+the land; for the great water-courses of the globe, and half
+the fresh water in the world, are found on the north side of
+the equator. This fact is strongly corroborative of this hypothesis.
+To evaporate water enough annually from the ocean
+to cover the earth, on the average, five feet deep with rain; to
+transport it from one zone to another; and to precipitate it
+in the right places at suitable times and in the proportions
+due,&mdash;is one of the offices of the grand atmospherical machine.
+This water is evaporated principally from the torrid zone. Supposing
+it all to come thence, we shall have encircling the earth
+a belt of ocean 3000 miles in breadth, from which this atmosphere
+evaporates a layer of water annually sixteen feet in
+depth. And to hoist up as high as the clouds, and lower down
+again, all the water, in a lake sixteen feet deep and 3000 miles
+broad and 24,000 long, is the yearly business of this invisible
+machinery. What a powerful engine is the atmosphere! and
+how nicely adjusted must be all the cogs and wheels and springs
+and <i>compensations</i> of this exquisite piece of machinery, that it
+never wears out nor breaks down, nor fails to do its work at
+the right time and in the right way!&mdash;<i>Maury.</i></p>
+
+<h3>THE PHILOSOPHY OF RAIN.</h3>
+
+<p>To understand the philosophy of this beautiful and often
+sublime phenomenon, a few facts derived from observation and
+a long train of experiments must be remembered.</p>
+
+<blockquote>
+
+<p>1. Were the atmosphere every where at all times at a uniform temperature,
+we should never have rain, or hail, or snow. The water absorbed
+by it in evaporation from the sea and the earth’s surface would
+descend in an imperceptible vapour, or cease to be absorbed by the air
+when it was once fully saturated.</p>
+
+<p>2. The absorbing power of the atmosphere, and consequently its
+capability to retain humidity, is proportionally greater in warm than in
+cold air.</p>
+
+<p>3. The air near the surface of the earth is warmer than it is in the
+region of the clouds. The higher we ascend from the earth, the colder
+do we find the atmosphere. Hence the perpetual snow on very high
+mountains in the hottest climate.</p></blockquote>
+
+<p><span class="pagenum"><a name="Page_154" id="Page_154">154</a></span>
+Now when, from continued evaporation, the air is highly
+saturated with vapour, though it be invisible and the sky cloudless,
+if its temperature is suddenly reduced by cold currents descending
+from above or rushing from a higher to a lower latitude,
+its capacity to retain moisture is diminished, clouds are
+formed, and the result is rain. Air condenses as it cools, and,
+like a sponge filled with water and compressed, pours out the
+water which its diminished capacity cannot hold. What but
+Omniscience could have devised such an admirable arrangement
+for watering the earth?</p>
+
+<h3>INORDINATE RAINY CLIMATE.</h3>
+
+<p>The climate of the Khasia mountains, which lie north-east
+from Calcutta, and are separated by the valley of the Burrampooter
+River from the Himalaya range, is remarkable for the
+inordinate fall of rain&mdash;the greatest, it is said, which has ever
+been recorded. Mr. Yule, an English gentleman, established that
+in the single month of August 1841 there fell 264 inches of rain,
+or 22 feet, of which 12½ feet fell in the space of five consecutive
+days. This astonishing fact is confirmed by two other
+English travellers, who measured 30 inches of rain in twenty-four
+hours, and during seven months above 500 inches. This
+great rain-fall is attributed to the abruptness of the mountains
+which face the Bay of Bengal, and the intervening flat
+swamps 200 miles in extent. The district of the excessive rain
+is extremely limited; and but a few degrees farther west, rain
+is said to be almost unknown, and the winter falls of snow to
+seldom exceed two inches.</p>
+
+<h3>HOW DOES THE NORTH WIND DRIVE AWAY RAIN?</h3>
+
+<p>We may liken it to a wet sponge, and the decrease of temperature
+to the hand that squeezes that sponge. Finally, reaching
+the cold latitudes, all the moisture that a dew-point of
+zero, and even far below, can extract, is wrung from it; and
+this air then commences “to return according to his circuits”
+as dry atmosphere. And here we can quote Scripture again:
+“The north wind driveth away rain.” This is a meteorological
+fact of high authority and great importance in the study
+of the circulation of the atmosphere.&mdash;<i>Maury.</i></p>
+
+<h3>SIZE OF RAIN-DROPS.</h3>
+
+<p>The Drops of Rain vary in their size, perhaps from the 25th
+to the ¼ of an inch in diameter. In parting from the clouds,
+they precipitate their descent till the increasing resistance opposed
+by the air becomes equal to their weight, when they
+continue to fall with uniform velocity. This velocity is, therefore,<span class="pagenum"><a name="Page_155" id="Page_155">155</a></span>
+in a certain ratio to the diameter of the drops; hence
+thunder and other showers in which the drops are large pour
+down faster than a drizzling rain. A drop of the 25th part of
+an inch, in falling through the air, would, when it had arrived
+at its uniform velocity, only acquire a celerity of 11½ feet per
+second; while one of ¼ of an inch would equal a velocity of
+33½ feet.&mdash;<i>Leslie.</i></p>
+
+<h3>RAINLESS DISTRICTS.</h3>
+
+<p>In several parts of the world there is no rain at all. In the
+Old World there are two districts of this kind: the desert of
+Sahara in Africa, and in Asia part of Arabia, Syria, and Persia;
+the other district lies between north latitude 30° and 50°,
+and between 75° and 118° of east longitude, including Thibet,
+Gobiar Shama, and Mongolia. In the New World the rainless
+districts are of much less magnitude, occupying two narrow
+strips on the shores of Peru and Bolivia, and on the coast of
+Mexico and Guatemala, with a small district between Trinidad
+and Panama on the coast of Venezuela.</p>
+
+<h3>ALL THE RAIN IN THE WORLD.</h3>
+
+<p>The Pacific Ocean and the Indian Ocean may be considered
+as one sheet of water covering an area quite equal in extent to
+one half of that embraced by the whole surface of the earth;
+and the total annual fall of rain on the earth’s surface is 186,240
+cubic imperial miles. Not less than three-fourths of the vapour
+which makes this rain comes from this waste of waters; but,
+supposing that only half of this quantity, that is 93,120 cubic
+miles of rain, falls upon this sea, and that that much at least
+is taken up from it again as vapour, this would give 255 cubic
+miles as the quantity of water which is daily lifted up and
+poured back again into this expanse. It is taken up at one
+place, and rained down at another; and in this process, therefore,
+we have agencies for multitudes of partial and conflicting
+currents, all, in their set strength, apparently as uncertain as
+the winds.</p>
+
+<p>The better to appreciate the operation of such agencies in
+producing currents in the sea, imagine a district of 255 square
+miles to be set apart in the midst of the Pacific Ocean as the
+scene of operations for one day; then conceive a machine capable
+of pumping up in the twenty-four hours all the water to
+the depth of one mile in this district. The machine must not
+only pump up and bear off this immense quantity of water, but
+it must discharge it again into the sea on the same day, but
+at some other place.</p>
+
+<p>All the great rivers of America, Europe, and Asia are lifted<span class="pagenum"><a name="Page_156" id="Page_156">156</a></span>
+up by the atmosphere, and flow in invisible streams back
+through the air to their sources among the hills; and through
+channels so regular, certain, and well defined, that the quantity
+thus conveyed one year with the other is nearly the same:
+for that is the quantity which we see running down to the
+ocean through these rivers; and the quantity discharged annually
+by each river is, as far as we can judge, nearly a constant.&mdash;<i>Maury.</i></p>
+
+<h3>AN INCH OF RAIN ON THE ATLANTIC.</h3>
+
+<p>Lieutenant Maury thus computes the effect of a single Inch
+of Rain falling upon the Atlantic Ocean. The Atlantic includes
+an area of twenty-five millions of square miles. Suppose an
+inch of rain to fall upon only one-fifth of this vast expanse. It
+would weigh, says our author, three hundred and sixty thousand
+millions of tons: and the salt which, as water, it held in
+solution in the sea, and which, when that water was taken up
+as vapour, was left behind to disturb equilibrium, weighed sixteen
+millions more of tons, or nearly twice as much as all the
+ships in the world could carry at a cargo each. It might fall
+in an hour, or it might fall in a day; but, occupy what time it
+might in falling, this rain is calculated to exert so much force&mdash;which
+is inconceivably great&mdash;in disturbing the equilibrium
+of the ocean. If all the water discharged by the Mississippi
+river during the year were taken up in one mighty measure,
+and cast into the ocean at one effort, it would not make a
+greater disturbance in the equilibrium of the sea than would
+the fall of rain supposed. And yet so gentle are the operations
+of nature, that movements so vast are unperceived.</p>
+
+<h3>THE EQUATORIAL CLOUD-RING.</h3>
+
+<p>In crossing the Equatorial Doldrums, the voyager passes a
+ring of clouds that encircles the earth, and is stretched around
+our planet to regulate the quantity of precipitation in the rain-belt
+beneath it; to preserve the due quantum of heat on the
+face of the earth; to adjust the winds; and send out for distribution
+to the four corners vapours in proper quantities, to
+make up to each river-basin, climate, and season, its quota of
+sunshine, cloud, and moisture. Like the balance-wheel of a
+well-constructed chronometer, this cloud-ring affords the grand
+atmospherical machine the most exquisitely arranged <i>self-compensation</i>.
+Nature herself has hung a thermometer under this
+cloud-belt that is more perfect than any that man can construct,
+and its indications are not to be mistaken.&mdash;<i>Maury.</i></p>
+
+<h3>“THE EQUATORIAL DOLDRUMS”</h3>
+
+<p class="in0">is another of these calm places. Besides being a region of<span class="pagenum"><a name="Page_157" id="Page_157">157</a></span>
+calms and baffling winds, it is a region noted for its rains and
+clouds, which make it one of the most oppressive and disagreeable
+places at sea. The emigrant ships from Europe for Australia
+have to cross it. They are often baffled in it for two or
+three weeks; then the children and the passengers who are of
+delicate health suffer most. It is a frightful graveyard on the
+wayside to that golden land.</p>
+
+<h3>BEAUTY OF THE DEW-DROP.</h3>
+
+<p>The Dew-drop is familiar to every one from earliest infancy.
+Resting in luminous beads on the down of leaves, or pendent
+from the finest blades of grass, or threaded upon the floating
+lines of the gossamer, its “orient pearl” varies in size from
+the diameter of a small pea to the most minute atom that can
+be imagined to exist. Each of these, like the rain-drops, has
+the properties of reflecting and refracting light; hence, from so
+many minute prisms, the unfolded rays of the sun are sent up
+to the eye in colours of brilliancy similar to those of the rainbow.
+When the sunbeams traverse horizontally a very thickly-bedewed
+grass-plot, these colours arrange themselves so as to
+form an iris, or dew-bow; and if we select any one of these
+drops for observation, and steadily regard it while we gradually
+change our position, we shall find the prismatic colours follow
+each other in their regular order.&mdash;<i>Wells.</i></p>
+
+<h3>FALL OF DEW IN ONE YEAR.</h3>
+
+<p>The annual average quantity of Dew deposited in this country
+is estimated at a depth of about five inches, being about
+one-seventh of the mean quantity of moisture supposed to be
+received from the atmosphere all over Great Britain in the
+year; or about 22,161,337,355 tons, taking the ton at 252 imperial
+gallons.&mdash;<i>Wells.</i></p>
+
+<h3>GRADUATED SUPPLY OF DEW TO VEGETATION.</h3>
+
+<p>Each of the different grasses draws from the atmosphere
+during the night a supply of dew to recruit its energies dependent
+upon its form and peculiar radiating power. Every
+flower has a power of radiation of its own, subject to changes
+during the day and night, and the deposition of moisture on
+it is regulated by the peculiar law which this radiating power
+obeys; and this power will be influenced by the aspect which
+the flower presents to the sky, unfolding to the contemplative
+mind the most beautiful example of creative wisdom.<a name="FNanchor_39" id="FNanchor_39" href="#Footnote_39" class="fnanchor">39</a></p>
+
+<p><span class="pagenum"><a name="Page_158" id="Page_158">158</a></span></p>
+
+<h3>WARMTH OF SNOW IN ARCTIC LATITUDES.</h3>
+
+<p>The first warm Snows of August and September (says Dr.
+Kane), falling on a thickly-bleached carpet of grasses, heaths,
+and willows, enshrine the flowery growths which nestle round
+them in a non-conducting air chamber; and as each successive
+snow increases the thickness of the cover, we have, before the
+intense cold of winter sets in, a light cellular bed covered by
+drift, seven, eight, or ten feet deep, in which the plant retains
+its vitality. Dr. Kane has proved by experiments that the
+conducting power of the snow is proportioned to its compression
+by winds, rains, drifts, and congelation. The drifts that
+accumulate during nine months of the year are dispersed in
+well-defined layers of different density. We have first the
+warm cellular snows of fall, which surround the plant; next
+the finely-impacted snow-dust of winter; and above these the
+later humid deposits of spring. In the earlier summer, in the
+inclined slopes that face the sun, as the upper snow is melted
+and sinks upon the more compact layer below it is to a great
+extent arrested, and runs off like rain from a slope of clay. The
+plant reposes thus in its cellular bed, safe from the rush of
+waters, and protected from the nightly frosts by the icy roof
+above it.</p>
+
+<h3>IMPURITY OF SNOW.</h3>
+
+<p>It is believed that in ascending mountains difficult breathing
+is sooner felt upon snow than upon rock; and M. Boussingault,
+in his account of the ascent of Chimborazo, attributes
+this to the sensible deficiency of oxygen contained in the pores
+of the snow, which is exhaled when it melts. The fact that
+the air absorbed by snow is impure, was ascertained by De
+Saussure, and has been confirmed by Boussingault’s experiments.&mdash;<i>Quarterly
+Review</i>, No. 202.</p>
+
+<h3>SNOW PHENOMENON.</h3>
+
+<p>Professor Dove of Berlin relates, in illustration of the formation
+of clouds of Snow over plains situated at a distance
+from the cooling summits of mountains, that on one occasion a
+large company had gathered in a ballroom in Sweden. It was
+one of those icy starlight nights which in that country are
+so aptly called “iron nights.” The weather was clear and
+cold, and the ballroom was clear and warm; and the heat was
+so great, that several ladies fainted. An officer present tried
+to open a window; but it was frozen fast to the sill. As a last
+resort, he broke a pane of glass; the cold air rushed in, and it
+<i>snowed in the room</i>. A minute before all was clear; but the<span class="pagenum"><a name="Page_159" id="Page_159">159</a></span>
+warm air of the room had sustained an amount of moisture in
+a transparent condition which it was not able to maintain
+when mixed with the colder air from without. The vapour
+was first condensed, and then frozen.</p>
+
+<h3>ABSENCE OF SNOW IN SIBERIA.</h3>
+
+<p>There is in Siberia, M. Ermann informs us, an <i>entire district</i>
+in which during the winter the sky is constantly clear, and
+where a single particle of snow never falls.&mdash;<i>Arago.</i></p>
+
+<h3>ACCURACY OF THE CHINESE AS OBSERVERS.</h3>
+
+<p>The beautiful forms of snow-crystals have long since attracted
+Chinese observers; for from a remote period there has
+been met with in their conversation and books an axiomatic
+expression, to the effect that “snow-flakes are hexagonal,”
+showing the Chinese to be accurate observers of nature.</p>
+
+<h3>PROTECTION AGAINST HAIL AND STORMS.</h3>
+
+<p>Arago relates, that when, in 1847, two small agricultural
+districts of Bourgoyne had lost by Hail crops to the value of
+a million and a half of francs, certain of the proprietors went
+to consult him on the means of protecting them from like
+disasters. Resting on the hypothesis of the electric origin of
+hail, Arago suggested the discharge of the electricity of the
+clouds by means of balloons communicating by a metallic wire
+with the soil. This project was not carried out; but Arago
+persisted in believing in the effectiveness of the method proposed.</p>
+
+<blockquote>
+
+<p>Arago, in his <i>Meteorological Essays</i>, inquires whether the firing of
+cannon can dissipate storms. He cites several cases in its favour, and
+others which seem to oppose it; but he concludes by recommending it
+to his successors. Whilst Arago was propounding these questions, a
+person not conversant with science, the poet Méry, was collecting facts
+supporting the view, which he has published in his <i>Paris Futur</i>. His
+attention was attracted to the firing of cannon to dissipate storms in
+1828, whilst an assistant in the “Ecole de Tir” at Vincennes. Having
+observed that there was never any rain in the morning of the exercise
+of firing, he waited to examine military records, and found there, as he
+says, facts which justified the expressions of “Le soleil d’Austerlitz,”
+“Le soleil de juillet,” upon the morning of the Revolution of July; and
+he concluded by proposing to construct around Paris twelve towers of
+great height, which he calls “tours imbrifuges,” each carrying 100 cannons,
+which should be discharged into the air on the approach of a
+storm. About this time an incident occurred which in nowise confirmed
+the truth of M. Méry’s theory. The 14th of August was a fine day. On
+the 15th, the fête of the Empire, the sun shone out, the cannon thundered
+all day long, fireworks and illuminations were blazing from nine
+o’clock in the evening. Every thing conspired to verify the hypothesis
+of M. Méry, and chase away storms for a long time. But towards<span class="pagenum"><a name="Page_160" id="Page_160">160</a></span>
+eleven in the evening a torrent of rain burst upon Paris, in spite of the
+pretended influence of the discharge of cannon, and gave an occasion
+for the mobile Gallic mind to turn its attention in other directions.</p></blockquote>
+
+<h3>TERRIFIC HAILSTORM.</h3>
+
+<p>Jansen describes, from the log-book of the <i>Rhijin</i>, Captain
+Brandligt, in the South-Indian Ocean (25° south latitude)
+a Hurricane, accompanied by Hail, by which several of the
+crew were made blind, others had their faces cut open, and
+those who were in the rigging had their clothes torn off them.
+The master of the ship compared the sea “to a hilly landscape
+in winter covered with snow.” Does it not appear as if the
+“treasures of the hail” were opened, which were “reserved
+against the time of trouble, against the day of battle and
+war”?</p>
+
+<h3>HOW WATERSPOUTS ARE FORMED IN THE JAVA SEA.</h3>
+
+<p>Among the small groups of islands in this sea, in the day
+and night thunderstorms, the combat of the clouds appears to
+make them more thirsty than ever. In tunnel form, when they
+can no longer quench their thirst from the surrounding atmosphere,
+they descend near the surface of the sea, and appear to
+lap the water directly up with their black mouths. They are
+not always accompanied by strong winds; frequently more
+than one is seen at a time, whereupon the clouds whence they
+proceed disperse, and the ends of the Waterspouts bending
+over finally causes them to break in the middle. They seldom
+last longer than five minutes. As they are going away, the
+bulbous tube, which is as palpable as that of a thermometer,
+becomes broader at the base; and little clouds, like steam from
+the pipe of a locomotive, are continually thrown off from the
+circumference of the spout, and gradually the water is released,
+and the cloud whence the spout came again closes its
+mouth.</p>
+
+<h3>COLD IN HUDSON’S BAY.</h3>
+
+<p>Mr. R. M. Ballantyne, in his journal of six years’ residence
+in the territories of the Hudson’s Bay Company, tells us, that
+for part of October there is sometimes a little warm, or rather
+thawy, weather; but after that, until the following April, the
+thermometer seldom rises to the freezing point. In the depth
+of winter, the thermometer falls from 30° to 40°, 45°, and even
+49° <i>below zero</i> of Fahrenheit. This intense cold is not, however,
+so much felt as one might suppose; for during its continuance
+the air is perfectly calm. Were the slightest breath of wind
+to rise when the thermometer stands so low, no man could
+show his face to it for a moment. Forty degrees below zero,<span class="pagenum"><a name="Page_161" id="Page_161">161</a></span>
+and quite calm, is infinitely preferable to fifteen below, or
+thereabout, with a strong breeze of wind. Spirit of wine is,
+of course, the only thing that can be used in the thermometer;
+as mercury, were it exposed to such cold, would remain frozen
+nearly half the winter. Spirit never froze in any cold ever
+experienced at York Factory, unless when very much adulterated
+with water; and even then the spirit would remain liquid
+in the centre of the mass. Quicksilver easily freezes in this
+climate, and it has frequently been run into a bullet-mould,
+exposed to the cold air till frozen, and in this state rammed
+down a gun-barrel, and fired through a thick plank. The
+average cold may be set down at about 15° or 16° below zero,
+or 48° of frost. The houses at the Bay are built of wood, with
+double windows and doors. They are heated by large iron
+stoves, fed with wood; yet so intense is the cold, that when
+a stove has been in places red-hot, a basin of water in the room
+has been frozen solid.</p>
+
+<h3>PURITY OF WENHAM-LAKE ICE.</h3>
+
+<p>Professor Faraday attributes the purity of Wenham-Lake
+Ice to its being free from air-bubbles and from salts. The
+presence of the first makes it extremely difficult to succeed in
+making a lens of English ice which will concentrate the solar
+rays, and readily fire gunpowder; whereas nothing is easier
+than to perform this singular feat of igniting a combustible
+body by aid of a frozen mass if Wenham-Lake ice be employed.
+The absence of salts conduces greatly to the permanence of the
+ice; for where water is so frozen that the salts expelled are
+still contained in air-cavities and cracks, or form thin films
+between the layers of ice, these entangled salts cause the ice to
+melt at a lower temperature than 32°, and the liquefied portions
+give rise to streams and currents within the body of the
+ice which rapidly carry heat to the interior. The mass then
+goes on thawing within as well as without, and at temperatures
+below 32°; whereas pure, compact, Wenham-Lake ice
+can only thaw at 32°, and only on the outside of the mass.&mdash;<i>Sir
+Charles Lyell’s Second Visit to the United States.</i></p>
+
+<h3>ARCTIC TEMPERATURES.</h3>
+
+<p>Dr. Kane, in his Second Arctic Expedition, found the thermometers
+beginning to show unexampled temperature: they
+ranged from 60° to 70° below zero, and upon the taffrail of the
+brig 65°. The reduced mean of the best spirit-standards gave
+67° or 99° below the freezing point of water. At these temperatures
+chloric ether became solid, and chloroform exhibited
+a granular pellicle on its surface. Spirit of naphtha froze at 54°,
+and the oil of turpentine was solid at 63° and 65°.</p>
+
+<p><span class="pagenum"><a name="Page_162" id="Page_162">162</a></span></p>
+
+<h3>DR. RAE’S ARCTIC EXPLORATIONS.</h3>
+
+<p>The gold medal of the Royal Geographical Society was in
+1852 most rightfully awarded to this indefatigable Arctic explorer.
+His survey of the inlet of Boothia, in 1848, was unique
+in its kind. In Repulse Bay he maintained his party on deer,
+principally shot by himself; and spent ten months of an Arctic
+winter in a hut of stones, with no other fuel than a kind of hay
+of the <i>Andromeda tetragona</i>. Thus he preserved his men to
+execute surveying journeys of 1000 miles in the spring. Later
+he travelled 300 miles on snow-shoes. In a spring journey over
+the ice, with a pound of fat daily for fuel, accompanied by two
+men only, and trusting solely for shelter to snow-houses, which
+he taught his men to build, he accomplished 1060 miles in
+thirty-nine days, or twenty-seven miles per day, including stoppages,&mdash;a
+feat never equalled in Arctic travelling. In the
+spring journey, and that which followed in the summer in
+boats, 1700 miles were traversed in eighty days. Dr. Rae’s
+greatest sufferings, he once remarked to Sir George Back, arose
+from his being obliged to sleep upon his frozen mocassins in
+order to thaw them for the morning’s use.</p>
+
+<h3>PHENOMENA OF THE ARCTIC CLIMATE.</h3>
+
+<p>Sir John Richardson, in his history of his Expedition to
+these regions, describes the power of the sun in a cloudless sky
+to have been so great, that he was glad to take shelter in the
+water while the crews were engaged on the portages; and he
+has never felt the direct rays of the sun so oppressive as on
+some occasions in the high latitudes. Sir John observes:</p>
+
+<blockquote>
+
+<p>The rapid evaporation of both snow and ice in the winter and spring,
+long before the action of the sun has produced the slightest thaw or
+appearance of moisture, is evident by many facts of daily occurrence.
+Thus when a shirt, after being washed, is exposed in the open air to a
+temperature of from 40° to 50° below zero, it is instantly rigidly frozen,
+and may be broken if violently bent. If agitated when in this condition
+by a strong wind, it makes a rustling noise like theatrical thunder.</p>
+
+<p>In consequence of the extreme dryness of the atmosphere in winter,
+most articles of English manufacture brought to Rupert’s Land are
+shrivelled, bent, and broken. The handles of razors and knives, combs,
+ivory scales, &amp;c., kept in the warm room, are changed in this way. The
+human body also becomes vividly electric from the dryness of the skin.
+One cold night I rose from my bed, and was going out to observe the
+thermometer, with no other clothing than my flannel night-dress, when
+on my hand approaching the iron latch of the door, a distinct spark
+was elicited. Friction of the skin at almost all times in winter produced
+the electric odour.</p>
+
+<p>Even at midwinter we had but three hours and a half of daylight.
+On December 20th I required a candle to write at the window at ten in
+the morning. The sun was absent ten days, and its place in the heavens<span class="pagenum"><a name="Page_163" id="Page_163">163</a></span>
+at noon was denoted by rays of light shooting into the sky above the
+woods.</p>
+
+<p>The moon in the long nights was a most beautiful object, that satellite
+being constantly above the horizon for nearly a fortnight together.
+Venus also shone with a brilliancy which is never witnessed in a sky
+loaded with vapours; and, unless in snowy weather, our nights were
+always enlivened by the beams of the aurora.</p></blockquote>
+
+<h3>INTENSE HEAT AND COLD OF THE DESERT.</h3>
+
+<p>Among crystalline bodies, rock-crystal, or silica, is the best
+conductor of heat. This fact accounts for the steadiness of
+temperature in one set district, and the extremes of Heat and
+Cold presented by day and night on such sandy wastes as the
+Sahara. The sand, which is for the most part silica, drinks-in
+the noon-day heat, and loses it by night just as speedily.</p>
+
+<p>The influence of the hot winds from the Sahara has been
+observed in vessels traversing the Atlantic at a distance of upwards
+of 1100 geographical miles from the African shores, by
+the coating of impalpable dust upon the sails.</p>
+
+<h3>TRANSPORTING POWER OF WINDS.</h3>
+
+<p>The greatest example of their power is the <i>sand-flood</i> of
+Africa, which, moving gradually eastward, has overwhelmed
+all the land capable of tillage west of the Nile, unless sheltered
+by high mountains, and threatens ultimately to obliterate the
+rich plain of Egypt.</p>
+
+<h3>EXHILARATION IN ASCENDING MOUNTAINS.</h3>
+
+<p>At all elevations of from 6000 to 11,000 feet, and not unfrequently
+for even 2000 feet more, the pedestrian enjoys a pleasurable
+feeling, imparted by the consciousness of existence,
+similar to that which is described as so fascinating by those
+who have become familiar with the desert-life of the East. The
+body seems lighter, the nervous power greater, the appetite is
+increased; and fatigue, though felt for a time, is removed by
+the shortest repose. Some travellers have described the sensation
+by the impression that they do not actually press the
+ground, but that the blade of a knife could be inserted between
+the sole of the foot and the mountain top.&mdash;<i>Quarterly Review</i>,
+No. 202.</p>
+
+<h3>TO TELL THE APPROACH OF STORMS.</h3>
+
+<p>The proximity of Storms has been ascertained with accuracy
+by various indications of the electrical state of the atmosphere.
+Thus Professor Scott, of Sandhurst College, observed in Shetland
+that drinking-glasses, placed in an inverted position upon
+a shelf in a cupboard on the ground-floor of Belmont House,<span class="pagenum"><a name="Page_164" id="Page_164">164</a></span>
+occasionally emitted sounds as if they were tapped with a knife,
+or raised a little and then let fall on the shelf. These sounds
+preceded wind; and when they occurred, boats and vessels were
+immediately secured. The strength of the sound is said to be
+proportioned to the tempest that follows.</p>
+
+<h3>REVOLVING STORMS.</h3>
+
+<p>By the conjoint labours of Mr. Redfield, Colonel Reid, and
+Mr. Piddington, on the origin and nature of hurricanes, typhoons,
+or revolving storms, the following important results
+have been obtained. Their existence in moderate latitudes on
+both sides the equator; their absence in the immediate neighbourhood
+of the equatorial regions; and the fact, that while
+in the northern latitudes these storms revolve in a direction
+contrary to the hands of a watch the face of which is placed
+upwards, in the southern latitudes they rotate in the opposite
+direction,&mdash;are shown to be so many additions to the long chain
+of evidence by which the rotation of the earth as a physical
+fact is demonstrated.</p>
+
+<h3>IMPETUS OF A STORM.</h3>
+
+<p>Captain Sir S. Brown estimates, from experiments made by
+him at the extremity of the Brighton-Chain Pier in a heavy
+south-west gale, that the waves impinge on a cylindrical surface
+one foot high and one foot in diameter with a force equal
+to eighty pounds, to which must be added that of the wind,
+which in a violent storm exerts a pressure of forty pounds. He
+computed the collective impetus of the waves on the lower part
+of a lighthouse proposed to be built on the Wolf Rock (exposed
+to the most violent storms of the Atlantic), of the surf on the
+upper part, and of the wind on the whole, to be equal to 100
+tons.</p>
+
+<h3>HOW TO MAKE A STORM-GLASS.</h3>
+
+<p>This instrument consists of a glass tube, sealed at one end,
+and furnished with a brass cap at the other end, through which
+the air is admitted by a very small aperture. Nearly fill the
+tube with the following solution: camphor, 2½ drams; nitrate
+of potash, 38 grains; muriate of ammonia, 38 grains; water, 9
+drams; rectified spirit, 9 drams. Dissolve with heat. At the
+ordinary temperature of the atmosphere, plumose crystals are
+formed. On the approach of stormy weather, these crystals appear
+compressed into a compact mass at the bottom of the tube;
+while during fine weather they assume their plumose character,
+and extend a considerable way up the glass. These results depend
+upon the condition of the air, but they are not considered
+to afford any reliable indication of approaching weather.</p>
+
+<p><span class="pagenum"><a name="Page_165" id="Page_165">165</a></span></p>
+
+<h3>SPLENDOUR OF THE AURORA BOREALIS.</h3>
+
+<p>Humboldt thus beautifully describes this phenomenon:</p>
+
+<blockquote>
+
+<p>The intensity of this light is at times so great, that Lowenörn (on
+June 29, 1786) recognised its coruscation in bright sunshine. Motion
+renders the phenomenon more visible. Round the point in the vault of
+heaven which corresponds to the direction of the inclination of the
+needle the beams unite together to form the so-called corona, the
+crown of the Northern Light, which encircles the summit of the heavenly
+canopy with a milder radiance and unflickering emanations of light.
+It is only in rare instances that a perfect crown or circle is formed; but
+on its completion, the phenomenon has invariably reached its maximum,
+and the radiations become less frequent, shorter, and more colourless.
+The crown, and the luminous arches break up; and the whole vault of
+heaven becomes covered with irregularly scattered, broad, faint, almost
+ashy-gray, luminous, immovable patches, which in their turn disappear,
+leaving nothing but a trace of a dark smoke-like segment on the
+horizon. There often remains nothing of the whole spectacle but a white
+delicate cloud with feathery edges, or divided at equal distances into
+small roundish groups like cirro-cumuli.&mdash;<i>Cosmos</i>, vol. i.</p></blockquote>
+
+<p>Among many theories of this phenomenon is that of Lieutenant
+Hooper, R.N., who has stated to the British Association
+that he believes “the Aurora Borealis to be no more nor less
+than the moisture in some shape (whether dew or vapour, liquid
+or frozen), illuminated by the heavenly bodies, either directly, or
+reflecting their rays from the frozen masses around the Pole,
+or even from the immediately proximate snow-clad earth.”</p>
+
+<h3>VARIETIES OF LIGHTNING.</h3>
+
+<p>According to Arago’s investigations, the evolution of Lightning
+is of three kinds: zigzag, and sharply defined at the
+edges; in sheets of light, illuminating a whole cloud, which
+seems to open and reveal the light within it; and in the form
+of fire-balls. The duration of the first two kinds scarcely continues
+the thousandth part of a second; but the globular lightning
+moves much more slowly, remaining visible for several
+seconds.</p>
+
+<h3>WHAT IS SHEET-LIGHTNING?</h3>
+
+<p>This electric phenomenon is unaccompanied by thunder, or
+too distant to be heard: when it appears, the whole sky, but
+particularly the horizon, is suddenly illuminated with a flickering
+flash. Philosophers differ much as to its cause. Matteucci
+supposes it to be produced either during evaporation, or
+evolved (according to Pouillet’s theory) in the process of vegetation;
+or generated by chemical action in the great laboratory
+of nature, the earth, and accumulated in the lower strata of the
+air in consequence of the ground being an imperfect conductor.</p>
+
+<p><span class="pagenum"><a name="Page_166" id="Page_166">166</a></span></p><blockquote>
+
+<p>Arago and Kamtz, however, consider sheet-lightning as <i>reflections
+of distant thunderstorms</i>. Saussure observed sheet-lightning in the direction
+of Geneva, from the Hospice du Grimsel, on the 10th and 11th
+of July 1783; while at the same time a terrific thunderstorm raged at
+Geneva. Howard, from Tottenham, near London, on July 31, 1813,
+saw sheet-lightning towards the south-east, while the sky was bespangled
+with stars, not a cloud floating in the air; at the same time a thunderstorm
+raged at Hastings, and in France from Calais to Dunkirk.
+Arago supports his opinion, that the phenomenon is <i>reflected lightning</i>,
+by the following illustration: In 1803, when observations were being
+made for determining the longitude, M. de Zach, on the Brocken, used
+a few ounces of gunpowder as a signal, the flash of which was visible
+from the Klenlenberg, sixty leagues off, although these mountains are
+invisible from each other.</p></blockquote>
+
+<h3>PRODUCTION OF LIGHTNING BY RAIN.</h3>
+
+<p>A sudden gust of rain is almost sure to succeed a violent
+detonation immediately overhead. Mr. Birt, the meteorologist,
+asks: Is this rain a <i>cause</i> or <i>consequence</i> of the electric discharge?
+To this he replies:</p>
+
+<blockquote>
+
+<p>In the sudden agglomeration of many minute and feebly electrified
+globules into one rain-drop, the quantity of electricity is increased in a
+greater proportion than the surface over which (according to the laws of
+electric distribution) it is spread. By tension, therefore, it is increased,
+and may attain the point when it is capable of separating from the <i>drop</i>
+to seek the surface of the <i>cloud</i>, or of the newly-formed descending body
+of rain, which, under such circumstances, may be regarded as a conducting
+medium. Arrived at this surface, the tension, for the same reason,
+becomes enormous, and a flash escapes. This theory Mr. Birt has confirmed
+by observation of rain in thunderstorms.</p></blockquote>
+
+<h3>SERVICE OF LIGHTNING-CONDUCTORS.</h3>
+
+<p>Sir David Brewster relates a remarkable instance of a tree
+in Clandeboye Park, in a thick mass of wood, and <i>not the tallest
+of the group</i>, being struck by lightning, which passed down the
+trunk into the ground, rending the tree asunder. This shows
+that an object may be struck by lightning in a locality where
+there are numerous conducting points more elevated than
+itself; and at the same time proves that lightning cannot be
+diverted from its course by lofty isolated conductors, but that
+the protection of buildings from this species of meteor can only
+be effected by conductors stretching out in all directions.</p>
+
+<p>Professor Silliman states, that lightning-rods cannot be relied
+upon unless they reach the earth where it is permanently
+wet; and that the best security is afforded by carrying the rod,
+or some good metallic conductor duly connected with it, to the
+water in the well, or to some other water that never fails. The
+professor’s house, it seems, was struck; but his lightning-rods
+were not more than two or three inches in the ground, and were
+therefore virtually of no avail in protecting the building.</p>
+
+<p><span class="pagenum"><a name="Page_167" id="Page_167">167</a></span></p>
+
+<h3>ANCIENT LIGHTNING-CONDUCTOR.</h3>
+
+<p>Humboldt informs us, that “the most important ancient
+notice of the relations between lightning and conducting metals
+is that of Ctesias, in his <i>Indica</i>, cap. iv. p. 190. He possessed
+two iron swords, presents from the king Artaxerxes Mnemon
+and from his mother Parasytis, which, when planted in the
+earth, averted clouds, hail, and <i>strokes of lightning</i>. He had
+himself seen the operation, for the king had twice made the
+experiment before his eyes.”&mdash;<i>Cosmos</i>, vol. ii.</p>
+
+<h3>THE TEMPLE OF JERUSALEM PROTECTED FROM LIGHTNING.</h3>
+
+<p>We do not learn, either from the Bible or Josephus, that
+the Temple at Jerusalem was ever struck by Lightning during
+an interval of more than a thousand years, from the time of
+Solomon to the year 70; although, from its situation, it was
+completely exposed to the violent thunderstorms of Palestine.</p>
+
+<p>By a fortuitous circumstance, the Temple was crowned with
+lightning-conductors similar to those which we now employ,
+and which we owe to Franklin’s discovery. The roof, constructed
+in what we call the Italian manner, and covered with
+boards of cedar, having a thick coating of gold, was garnished
+from end to end with long pointed and gilt iron or steel lances,
+which, Josephus says, were intended to prevent birds from roosting
+on the roof and soiling it. The walls were overlaid throughout
+with wood, thickly gilt. Lastly, there were in the courts
+of the Temple cisterns, into which the rain from the roof was
+conducted by <i>metallic pipes</i>. We have here both the lightning-rods
+and a means of conduction so abundant, that Lichtenberg
+is quite right in saying that many of the present apparatuses
+are far from offering in their construction so satisfactory a
+combination of circumstances.&mdash;<i>Abridged from Arago’s Meteorological
+Essays.</i></p>
+
+<h3>HOW ST. PAUL’S CATHEDRAL IS PROTECTED FROM LIGHTNING.</h3>
+
+<p>In March 1769, the Dean and Chapter of St. Paul’s addressed
+a letter to the Royal Society, requesting their opinion
+as to the best and most effectual method of fixing electrical
+conductors on the cathedral. A committee was formed for the
+purpose, and Benjamin Franklin was one of the members; their
+report was made, and the conductors were fixed as follows:</p>
+
+<blockquote>
+
+<p>The seven iron scrolls supporting the ball and cross are connected
+with other rods (used merely as conductors), which unite them with
+several large bars, descending obliquely to the stone-work of the lantern,
+and connected by an iron ring with four other iron bars to the lead
+covering of the great cupola, a distance of forty-eight feet; thence the<span class="pagenum"><a name="Page_168" id="Page_168">168</a></span>
+communication is continued by the rain-water pipes to the lead-covered
+roof, and thence by lead water-pipes which pass into the earth; thus
+completing the entire communication from the cross to the ground,
+partly through iron, and partly through lead. On the clock-tower a
+bar of iron connects the pine-apple at the top with the iron staircase,
+and thence with the lead on the roof of the church. The bell-tower is
+similarly protected. By these means the metal used in the building is
+made available as conductors; the metal employed merely for that purpose
+being exceedingly small in quantity.&mdash;<i>Curiosities of London.</i></p></blockquote>
+
+<h3>VARIOUS EFFECTS OF LIGHTNING.</h3>
+
+<p>Dr. Hibbert tells us that upon the western coast of Scotland
+and Ireland, Lightning coöperates with the violence of
+the storm in shattering solid rocks, and heaping them in piles
+of enormous fragments, both on dry land and beneath the
+water.</p>
+
+<p>Euler informs us, in his <i>Letters to a German Princess</i>, that
+he corresponded with a Moravian priest named Divisch, who
+assured him that he had averted during a whole summer every
+thunderstorm which threatened his own habitation and the
+neighbourhood, by means of a machine constructed upon the
+principles of electricity; that the machinery sensibly attracted
+the clouds, and constrained them to descend quietly in a distillation,
+without any but a very distant thunderclap. Euler
+assures us that “the fact is undoubted, and confirmed by irresistible
+proof.”</p>
+
+<p>About the year 1811, in the village of Phillipsthal, in Eastern
+Prussia, an attempt was made to split an immense stone
+into a multitude of pieces by means of lightning. A bar of
+iron, in the form of a conductor, was previously fixed to the
+stone; and the experiment was attended with complete success;
+for during the very first thunderstorm the lightning burst the
+stone without displacing it.</p>
+
+<p>The celebrated Duhamel du Monceau says, that lightning,
+unaccompanied by thunder, wind, or rain, has the property of
+breaking oat-stalks. The farmers are acquainted with this
+effect, and say that the lightning breaks down the oats. This
+is a well-received opinion with the farmers in Devonshire.</p>
+
+<p>Lightning has in some cases the property of reducing solid
+bodies to ashes, or to pulverisation,&mdash;even the human body,&mdash;without
+there being any signs of heat. The effects of lightning
+on paralysis are very remarkable, in some cases curing, in others
+causing, that disease.</p>
+
+<p>The returning stroke of lightning is well known to be due
+to the restoration of the natural electric state, after it has been
+disturbed by induction.</p>
+
+<p><span class="pagenum"><a name="Page_169" id="Page_169">169</a></span></p>
+
+<h3>A THUNDERSTORM SEEN FROM A BALLOON.</h3>
+
+<p>Mr. John West, the American aeronaut, in his observations
+made during his numerous ascents, describes a storm viewed
+from above the clouds to have the appearance of ebullition.
+The bulging upper surface of the cloud resembles a vast sea of
+boiling and upheaving snow; the noise of the falling rain is
+like that of a waterfall over a precipice; the thunder above
+the cloud is not loud, and the flashes of lightning appear like
+streaks of intensely white fire on a surface of white vapour.
+He thus describes a side view of a storm which he witnessed
+June 3, 1852, in his balloon excursion from Portsmouth, Ohio:</p>
+
+<blockquote>
+
+<p>Although the sun was shining on me, the rain and small hail were
+rattling on the balloon. A rainbow, or prismatically-coloured arch or
+horse-shoe, was reflected against the sun; and as the point of observation
+changed laterally and perpendicularly, the perspective of this golden
+grotto changed its hues and forms. Above and behind this arch was
+going on the most terrific thunder; but no zigzag lightning was perceptible,
+only bright flashes, like explosions of “Roman candles” in
+fireworks. Occasionally there was a zigzag explosion in the cloud immediately
+below, the thunder sounding like a <i>feu-de-joie</i> of a rifle-corps.
+Then an orange-coloured wave of light seemed to fall from the upper to
+the lower cloud; this was “still-lightning.” Meanwhile intense electrical
+action was going on <i>in the balloon</i>, such as expansion, tremulous
+tension, lifting papers ten feet out of the car below the balloon and
+then dropping them, &amp;c. The close view of this Ohio storm was truly
+sublime; its rushing noise almost appalling.</p></blockquote>
+
+<p>Ascending from the earth with a balloon, in the rear of a
+storm, and mounted up a thousand feet above it, the balloon
+will soon override the storm, and may descend in advance of
+it. Mr. West has experienced this several times.</p>
+
+<h3>REMARKABLE AERONAUTIC VOYAGE.</h3>
+
+<p>Mr. Sadler, the celebrated aeronaut, ascended on one occasion
+in a balloon from Dublin, and was wafted across the Irish
+Channel; when, on his approach to the Welsh coast, the balloon
+descended nearly to the surface of the sea. By this time the
+sun was set, and the shades of evening began to close in. He
+threw out nearly all his ballast, and suddenly sprang upward
+to a great height; and by so doing brought his horizon to <i>dip</i>
+below the sun, producing the whole phenomenon of a western
+sunrise. Subsequently descending in Wales, he of course
+witnessed a second sunset on the same evening.&mdash;<i>Sir John
+Herschel’s Outlines of Astronomy.</i></p>
+
+<hr />
+
+<p><span class="pagenum"><a name="Page_170" id="Page_170">170</a></span></p>
+
+<div class="chapter"></div>
+<h2 title="Physical Geography of the Sea."><a name="Geography" id="Geography"></a>Physical Geography of the Sea.<a name="FNanchor_40" id="FNanchor_40" href="#Footnote_40" class="fnanchor smaller">40</a></h2>
+
+<h3>CLIMATES OF THE SEA.</h3>
+
+<p>The fauna and flora of the Sea are as much the creatures
+of Climate, and are as dependent for their well-being upon
+temperature, as are the fauna and flora of the dry land. Were
+it not so, we should find the fish and the algæ, the marine
+insect and the coral, distributed equally and alike in all parts
+of the ocean; the polar whale would delight in the torrid
+zone; and the habitat of the pearl oyster would be also under
+the iceberg, or in frigid waters colder than the melting ice.</p>
+
+<h3>THE CIRCULATION OF THE SEA.</h3>
+
+<p>The coral islands, reefs, and beds with which the Pacific
+Ocean is studded and garnished, were built up of materials
+which a certain kind of insect quarried from the sea-water.
+The currents of the sea ministered to this little insect; they
+were its <i>hod-carriers</i>. When fresh supplies of solid matter
+were wanted for the coral rock upon which the foundations of
+the Polynesian Islands were laid, these hod-carriers brought
+them in unfailing streams of sea-water, loaded with food and
+building-materials for the coralline: the obedient currents
+thread the widest and the deepest sea. Now we know that
+its adaptations are suited to all the wants of every one of its
+inhabitants,&mdash;to the wants of the coral insect as well as those
+of the whale. Hence <i>we know</i> that the sea has its system of
+circulation: for it transports materials for the coral rock from
+one part of the world to another; its currents receive them
+from rivers, and hand them over to the little mason for the
+structure of the most stupendous works of solid masonry that
+man has ever seen&mdash;the coral islands of the sea.</p>
+
+<h3>TEMPERATURE OF THE SEA.</h3>
+
+<p>Between the hottest hour of the day and the coldest hour
+of the night there is frequently a change of four degrees in
+the Temperature of the Sea. Taking one-fifth of the Atlantic
+Ocean for the scene of operation, and the difference of four<span class="pagenum"><a name="Page_171" id="Page_171">171</a></span>
+degrees to extend only ten feet below the surface, the total and
+absolute change made in such a mass of sea-water, by altering
+its temperature two degrees, is equivalent to a change in its
+volume of 390,000,000 cubic feet.</p>
+
+<h3>TRANSPARENCY OF THE OCEAN.</h3>
+
+<p>Captain Glynn, U.S.N., has made some interesting observations,
+ranging over 200° of latitude, in different oceans, in
+very high latitudes, and near the equator. His apparatus was
+simple: a common white dinner-plate, slung so as to lie in
+the water horizontally, and sunk by an iron pot with a line.
+Numbering the fathoms at which the plate was visible below
+the surface, Captain Glynn saw it on two occasions, at the
+maximum, twenty-five fathoms (150 feet) deep; the water was
+extraordinarily clear, and to lie in the boat and look down was
+like looking down from the mast-head; and the objects were
+clearly defined to a great depth.</p>
+
+<h3>THE BASIN OF THE ATLANTIC.</h3>
+
+<p>In its entire length, the basin of this sea is a long trough,
+separating the Old World from the New, and extending probably
+from pole to pole.</p>
+
+<p>This ocean-furrow was scored into the solid crust of our
+planet by the Almighty hand, that there the waters which
+“he called seas” might be gathered together so as to “let the
+dry land appear,” and fit the earth for the habitation of man.</p>
+
+<p>From the top of Chimborazo to the bottom of the Atlantic,
+at the deepest place yet recognised by the plummet in the
+North Atlantic, the distance in a vertical line is nine miles.</p>
+
+<p>Could the waters of the Atlantic be drawn off, so as to
+expose to view this great sea-gash, which separates continents,
+and extends from the Arctic to the Antarctic, it would present
+a scene the most grand, rugged, and imposing. The very ribs
+of the solid earth, with the foundations of the sea, would be
+brought to light; and we should have presented to us at one
+view, in the empty cradle of the ocean, “a thousand fearful
+wrecks,” with that dreadful array of dead men’s skulls, great
+anchors, heaps of pearls and inestimable stones, which, in the
+dreamer’s eye, lie scattered on the bottom of the sea, making
+it hideous with sights of ugly death.</p>
+
+<h3>GALES OF THE ATLANTIC.</h3>
+
+<p>Lieutenant Maury has, in a series of charts of the North
+and South Atlantic, exhibited, by means of colours, the prevalence
+of Gales over the more stormy parts of the oceans for
+each month in the year. One colour shows the region in which<span class="pagenum"><a name="Page_172" id="Page_172">172</a></span>
+there is a gale every six days; another colour every six to ten
+days; another every ten to fourteen days: and there is a separate
+chart for each month and each ocean.</p>
+
+<h3>SOLITUDE AT SEA.</h3>
+
+<p>Between Humboldt’s Current of Peru and the great equatorial
+flow, there is “a desolate region,” rarely visited by the
+whale, either sperm or right. Formerly this part of the ocean
+was seldom whitened by the sails of a ship, or enlivened by the
+presence of man. Neither the industrial pursuits of the sea
+nor the highways of commerce called him into it. Now and
+then a roving cruiser or an enterprising whalesman passed that
+way; but to all else it was an unfrequented part of the ocean,
+and so remained until the gold-fields of Australia and the
+guano islands of Peru made it a thoroughfare. All vessels
+bound from Australia to South America now pass through it;
+and in the journals of some of them it is described as a region
+almost void of the signs of life in both sea and air. In the
+South-Pacific Ocean especially, where there is such a wide expanse
+of water, sea-birds often exhibit a companionship with
+a vessel, and will follow and keep company with it through
+storm and calm for weeks together. Even the albatross and
+Cape pigeon, that delight in the stormy regions of Cape Horn
+and the inhospitable climates of the Antarctic regions, not unfrequently
+accompany vessels into the perpetual summer of the
+tropics. The sea-birds that join the ship as she clears Australia
+will, it is said, follow her to this region, and then disappear.
+Even the chirp of the stormy petrel ceases to be heard
+here, and the sea itself is said to be singularly barren of “moving
+creatures that have life.”</p>
+
+<h3>BOTTLES AND CURRENTS AT SEA.</h3>
+
+<p>Seafaring people often throw a bottle overboard, with a
+paper stating the time and place at which it is done. In the
+absence of other information as to Currents, that afforded by
+these mute little navigators is of great value. They leave no
+track behind them, it is true, and their routes cannot be ascertained;
+but knowing where they are cast, and seeing where
+they are found, some idea may be formed as to their course.
+Straight lines may at least be drawn, showing the shortest distance
+from the beginning to the end of their voyage, with the
+time elapsed. Admiral Beechey has prepared a chart, representing,
+in this way, the tracks of more than 100 bottles.
+From this it appears that the waters from every quarter of the
+Atlantic tend towards the Gulf of Mexico and its stream. Bottles
+cast into the sea midway between the Old and the New<span class="pagenum"><a name="Page_173" id="Page_173">173</a></span>
+Worlds, near the coasts of Europe, Africa, and America at the
+extreme north or farthest south, have been found either in the
+West Indies, or the British Isles, or within the well-known
+range of Gulf-Stream waters.</p>
+
+<h3>“THE HORSE LATITUDES”</h3>
+
+<p class="in0">are the belts of calms and light airs which border the polar
+edge of the north-east trade-winds. They are so called from
+the circumstance that vessels formerly bound from New England
+to the West Indies, with a deck-load of horses, were often
+so delayed in this calm belt of Cancer, that, from the want of
+water for their animals, they were compelled to throw a portion
+of them overboard.</p>
+
+<h3>“WHITE WATER” AND LUMINOUS ANIMALS AT SEA.</h3>
+
+<p>Captain Kingman, of the American clipper-ship <i>Shooting
+Star</i>, in lat. 8° 46′ S., long. 105° 30′ E., describes a patch of
+<i>white water</i>, about twenty-three miles in length, making the
+whole ocean appear like a plain covered with snow. He filled
+a 60-gallon tub with the water, and found it to contain small
+luminous particles seeming to be alive with worms and insects,
+resembling a grand display of rockets and serpents seen
+at a great distance in a dark night; some of the serpents appearing
+to be six inches in length, and very luminous. On
+being taken up, they emitted light until brought within a few
+feet of a lamp, when nothing was visible; but by aid of a sextant’s
+magnifier they could be plainly seen&mdash;a jelly-like substance,
+without colour. A specimen two inches long was visible
+to the naked eye; it was about the size of a large hair, and
+tapered at the ends. By bringing one end within about one-fourth
+of an inch of a lighted lamp, the flame was attracted
+towards it, and burned with a red light; the substance crisped
+in burning, something like hair, or appeared of a red heat
+before being consumed. In a glass of the water there were
+several small round substances (say 1/16th of an inch in diameter)
+which had the power of expanding and contracting; when expanded,
+the outer rim appeared like a circular saw, the teeth
+turned inward.</p>
+
+<p>The scene from the clipper’s deck was one of awful grandeur:
+the sea having turned to phosphorus, and the heavens
+being hung in blackness, and the stars going out, seemed to
+indicate that all nature was preparing for that last grand conflagration
+which we are taught to believe will annihilate this
+material world.</p>
+
+<h3>INVENTION OF THE LOG.</h3>
+
+<p>Long before the introduction of the Log, hour-glasses were<span class="pagenum"><a name="Page_174" id="Page_174">174</a></span>
+used to tell the distance in sailing. Columbus, Juan de la
+Cosa, Sebastian Cabot, and Vasco de Gama, were not acquainted
+with the Log and its mode of application; and they estimated
+the ship’s speed merely by the eye, while they found the distance
+they had made by the running-down of the sand in the
+<i>ampotellas</i>, or hour-glasses. The Log for the measurement of
+the distance traversed is stated by writers on navigation not to
+have been invented until the end of the sixteenth or the beginning
+of the seventeenth century (see <i>Encyclopædia Britannica</i>,
+7th edition, 1842). The precise date is not known; but it is
+certain that Pigafetta, the companion of Magellan, speaks, in
+1521, of the Log as a well-known means of finding the course
+passed over. Navarete places the use of the log-line in English
+ships in 1577.</p>
+
+<h3>LIFE OF THE SEA-DEEPS.</h3>
+
+<p>The ocean teems with life, we know. Of the four elements
+of the old philosophers,&mdash;fire, earth, air, and water,&mdash;perhaps
+the sea most of all abounds with living creatures. The space
+occupied on the surface of our planet by the different families
+of animals and their remains is inversely as the size of the individual;
+the smaller the animal, generally speaking, the greater
+the space occupied by his remains. Take the elephant and his
+remains, and a microscopic animal and his, and compare them;
+the contrast as to space occupied is as striking as that of the
+coral reef or island with the dimensions of the whale. The
+graveyard that would hold the corallines, is larger than the
+graveyard that would hold the elephants.</p>
+
+<h3>DEPTHS OF OCEAN AND AIR UNKNOWN.</h3>
+
+<p>At some few places under the tropics, no bottom has been
+found with soundings of 26,000 feet, or more than four miles;
+whilst in the air, if, according to Wollaston, we may assume
+that it has a limit from which waves of sound may be reverberated,
+the phenomenon of twilight would incline us to assume
+a height at least nine times as great. The aerial ocean rests
+partly on the solid earth, whose mountain-chains and elevated
+plateaus rise like green wooded shoals, and partly on the sea,
+whose surface forms a moving base, on which rest the lower,
+denser, and more saturated strata of air.&mdash;<i>Humboldt’s Cosmos</i>,
+vol. i.</p>
+
+<p>The old Alexandrian mathematicians, on the testimony of
+Plutarch, believed the depth of the sea to depend on the height
+of the mountains. Mr. W. Darling has propounded to the
+British Association the theory, that as the sea covers three
+times the area of the land, so it is reasonable to suppose that
+the depth of the ocean, and that for a large portion, is three<span class="pagenum"><a name="Page_175" id="Page_175">175</a></span>
+times as great as the height of the highest mountain. Recent
+soundings show depths in the sea much greater than any elevations
+on the surface of the earth; for a line has been veered
+to the extent of seven miles.&mdash;<i>Dr. Scoresby.</i></p>
+
+<h3>GREATEST ASCERTAINED DEPTH OF THE SEA.</h3>
+
+<p>In the dynamical theory of the tides, the ratio of the effects
+of the sun and moon depends, not only on the masses, distances,
+and periodic times of the two luminaries, but also on
+the Depth of the Sea; and this, accordingly, may be computed
+when the other quantities are known. In this manner Professor
+Haughton has deduced, from the solar and lunar coefficients
+of the diurnal tide, a mean depth of 5·12 miles; a
+result which accords in a remarkable manner with that inferred
+from the ratio of the semi-diurnal co-efficients as obtained by
+Laplace from the Brest observations. Professor Hennessey
+states, that from what is now known regarding the depth of the
+ocean, the continents would appear as plateaus elevated above
+the oceanic depressions to an amount which, although small
+compared to the earth’s radius, would be considerable when
+compared to its outswelling at the equator and its flattening
+towards the poles; and the surface thus presented would be
+the true surface of the earth.</p>
+
+<p>The greatest depths at which the bottom of the sea has been
+reached with the plummet are in the North-Atlantic Ocean;
+and the places where it has been fathomed (by the United-States
+deep-sea sounding apparatus) do not show it to be
+deeper than 25,000 feet = 4 miles, 1293 yards, 1 foot. The
+deepest place in this ocean is probably between the parallels
+of 35° and 40° north latitude, and immediately to the southward
+of the Grand Banks of Newfoundland.</p>
+
+<blockquote>
+
+<p>It appears that, with one exception, the bottom of the North-Atlantic
+Ocean, as far as examined, from the depth of about sixty fathoms
+to that of more than two miles (2000 fathoms), is literally nothing but
+a mass of microscopic shells. Not one of the animalcules from these
+shells has been found living in the surface-waters, nor in shallow water
+along the shore. Hence arises the question, Do they live on the bottom,
+at the immense depths where the shells are found; or are they borne by
+submarine currents from their real habitat?</p></blockquote>
+
+<h3>RELATIVE LEVELS OF THE RED SEA AND MEDITERRANEAN.</h3>
+
+<p>The French engineers, at the beginning of the present century,
+came to the conclusion that the Red Sea was about thirty
+feet above the Mediterranean: but the observations of Mr.
+Robert Stephenson, the English engineer, at Suez; of M. Negretti,
+the Austrian, at Tineh, near the ancient Pelusium; and
+the levellings of Messrs. Talabat, Bourdaloue, and their assistants<span class="pagenum"><a name="Page_176" id="Page_176">176</a></span>
+between the two seas;&mdash;have proved that the low-water
+mark of ordinary tides at Suez and Tineh is very nearly on the
+same levels, the difference being that at Suez it is rather more
+than one inch lower.&mdash;<i>Leonard Horner</i>; <i>Proceedings of the Royal
+Society</i>, 1855.</p>
+
+<h3>THE DEPTH OF THE MEDITERRANEAN.</h3>
+
+<p>Soundings made in the Mediterranean suffice to indicate
+depths equal to the average height of the mountains girding
+round this great basin; and, if one particular experiment may
+be credited, reaching even to 15,000 feet&mdash;an equivalent to the
+elevation of the highest Alps. This sounding was made about
+ninety miles east of Malta. Between Cyprus and Egypt, 6000
+feet of line had been let down without reaching the bottom.
+Other deep soundings have been made in other places with
+similar results. In the lines of sea between Egypt and the
+Archipelago, it is stated that one sounding made by the <i>Tartarus</i>
+between Alexandria and Rhodes reached bottom at the
+depth of 9900 feet; another, between Alexandria and Candia,
+gave a depth of 300 feet beyond this. These single soundings,
+indeed, whether of ocean or sea, are always open to the certainty
+that greater as well as lesser depths must exist, to which
+no line has ever been sunk; a case coming under that general
+law of probabilities so largely applicable in every part of physics.
+In the Mediterranean especially, which has so many aspects of
+a sunken basin, there may be abysses of depth here and there
+which no plummet is ever destined to reach.&mdash;<i>Edinburgh Review.</i></p>
+
+<h3>COLOUR OF THE RED SEA.</h3>
+
+<p>M. Ehrenberg, while navigating the Red Sea, observed that
+the red colour of its waters was owing to enormous quantities
+of a new animal, which has received the name of <i>oscillatoria
+rubescens</i>, and which seems to be the same with what Haller
+has described as a <i>purple conferva</i> swimming in water; yet Dr.
+Bonar, in his work entitled <i>The Desert of Sinai</i>, records:</p>
+
+<blockquote>
+
+<p>Blue I have called the sea; yet not strictly so, save in the far distance.
+It is neither a <i>red</i> nor a <i>blue</i> sea, but emphatically green,&mdash;yes,
+green, of the most brilliant kind I ever saw. This is produced by the
+immense tracts of shallow water, with yellow sand beneath, which always
+gives this green to the sea, even in the absence of verdure on the shore
+or sea-weeds beneath. The <i>blue</i> of the sky and the <i>yellow</i> of the sands
+meeting and intermingling in the water, form the <i>green</i> of the sea; the
+water being the medium in which the mixing or fusing of the colours
+takes place.</p></blockquote>
+
+<h3>WHAT IS SEA-MILK?</h3>
+
+<p>The phenomena with this name and that of “Squid” are
+occasioned by the presence of phosphorescent animalcules. They<span class="pagenum"><a name="Page_177" id="Page_177">177</a></span>
+are especially produced in the intertropical seas, and they appear
+to be chiefly abundant in the Gulf of Guinea and in the
+Arabian Gulf. In the latter, the phenomenon was known to
+the ancients more than a century before the Christian era, as
+may be seen from a curious passage from the geography of Agatharcides:
+“Along this country (the coast of Arabia) the sea
+has a white aspect like a river: the cause of this phenomenon
+is a subject of astonishment to us.” M. Quatrefages has discovered
+that the <i>Noctilucæ</i> which produce this phenomenon do
+not always give out clear and brilliant sparks, but that under
+certain circumstances this light is replaced by a steady clearness,
+which gives in these animalcules a white colour. The
+waters in which they have been observed do not change their
+place to any sensible degree.</p>
+
+<h3>THE BOTTOM OF THE SEA A BURIAL-PLACE.</h3>
+
+<p>Among the minute shells which have been fished up from
+the great telegraphic plateau at the bottom of the sea between
+Newfoundland and Ireland, the microscope has failed to detect
+a single particle of sand or gravel; and the inference is, that
+there, if any where, the waters of the sea are at rest. There
+is not motion enough there to abrade these very delicate organisms,
+nor current enough to sweep them about and mix
+them up with a grain of the finest sand, nor the smallest particle
+of gravel from the loose beds of <i>débris</i> that here and there
+strew the bottom of the sea. The animalculæ probably do not
+live or die there. They would have had no light there; and,
+if they lived there, their frail textures would be subjected in
+their growth to a pressure upon them of a column of water
+12,000 feet high, equal to the weight of 400 atmospheres.
+They probably live and sport near the surface, where they
+can feel the genial influence of both light and heat, and are
+buried in the lichen caves below after death.</p>
+
+<p>It is now suggested, that henceforward we should view the
+surface of the sea as a nursery teeming with nascent organisms,
+and its depths as the cemetery for families of living creatures
+that outnumber the sands on the sea-shore for multitude.</p>
+
+<p>Where there is a nursery, hard by there will be found also a
+graveyard,&mdash;such is the condition of the animal world. But it
+never occurred to us before to consider the surface of the sea
+as one wide nursery, its every ripple as a cradle, and its bottom
+one vast burial-place.&mdash;<i>Lieut. Maury.</i></p>
+
+<h3>WHY IS THE SEA SALT?</h3>
+
+<p>It has been replied, In order to preserve it in a state of
+purity; which is, however, untenable, mainly from the fact that<span class="pagenum"><a name="Page_178" id="Page_178">178</a></span>
+organic impurities in a vast body of moving water, whether
+fresh or salt, become rapidly lost, so as apparently to have
+called forth a special agency to arrest the total organised matter
+in its final oscillation between the organic and inorganic worlds.
+Thus countless hosts of microscopic creatures swarm in most
+waters, their principal function being, as Professor Owen surmises,
+to feed upon and thus restore to the living chain the
+almost unorganised matter of various zones. These creatures
+preying upon one another, and being preyed upon by others in
+their turn, the circulation of organic matter is kept up. If we
+do not adopt this view, we must at least look upon the Infusoria
+and Foraminifera as scavenger agents to prevent an undue
+accumulation of decaying matter; and thus the salt condition
+of the sea is not a necessity.</p>
+
+<p>Nor is the amount of saline matter in the sea sufficient to
+arrest decomposition. That the sea is salt to render it of
+greater density, and by lowering its freezing point to preserve
+it from congelation to within a shorter distance of the poles,
+though admissible, scarcely meets the entire solution of the
+question. The freezing point of sea-water, for instance, is only
+3½° F. lower than that of fresh water; hence, with the present
+distribution of land and sea&mdash;and still less, probably, with that
+which obtained in former geological epochs&mdash;no very important
+effects would have resulted had the ocean been fresh instead of
+salt.</p>
+
+<p>Now Professor Chapman, of Toronto, suggests that the salt
+condition of the sea is mainly intended to regulate evaporation,
+and to prevent an undue excess of that phenomenon; saturated
+solutions evaporating more slowly than weak ones, and these
+latter more slowly again than pure water.</p>
+
+<p>Here, then, we have a self-adjusting phenomenon and admirable
+contrivance in the balance of forces. If from any temporary
+cause there be an unusual amount of saline matter in the
+sea, evaporation goes on the more and more slowly; and, on
+the other hand, if this proportion be reduced by the addition of
+fresh water in undue excess, the evaporating power is the more
+and more increased&mdash;thus aiding time, in either instance, to
+restore the balance. The perfect system of oceanic circulation
+may be ascribed, in a great degree at least, if not wholly, to
+the effect produced by the salts of the sea upon the mobility and
+circulation of its waters.</p>
+
+<p>Now this is an office which the sea performs in the economy
+of the universe by virtue of its saltness, and which it
+could not perform were its waters altogether fresh. And thus
+philosophers have a clue placed in their hands which will probably
+guide to one of the many hidden reasons that are embraced
+in the true answer to the question, “<i>Why is the sea salt?</i>”</p>
+
+<p><span class="pagenum"><a name="Page_179" id="Page_179">179</a></span></p>
+
+<h3>HOW TO ASCERTAIN THE SALTNESS OF THE SEA.</h3>
+
+<p>Dry a towel in the sun, weigh it carefully, and note its
+weight. Then dip it into sea-water, wring it sufficiently to
+prevent its dripping, and weigh it again; the increase of the
+weight being that of the water imbibed by the cloth. It should
+then be thoroughly dried, and once more weighed; and the excess
+of this weight above the original weight of the cloth shows
+the quantity of the salt retained by it; then, by comparing
+the weight of this salt with that of the sea-water imbibed by
+the cloth, we shall find what proportion of salt was contained
+in the water.</p>
+
+<h3>ALL THE SALT IN THE SEA.</h3>
+
+<p>The amount of common Salt in all the oceans is estimated
+by Schafhäutl at 3,051,342 cubic geographical miles. This
+would be about five times more than the mass of the Alps, and
+only one-third less than that of the Himalaya. The sulphate of
+soda equals 633,644·36 cubic miles, or is equal to the mass of
+the Alps; the chloride of magnesium, 441,811·80 cubic miles;
+the lime salts, 109,339·44 cubic miles. The above supposes the
+mean depth to be but 300 metres, as estimated by Humboldt.
+Admitting, with Laplace, that the mean depth is 1000 metres,
+which is more probable, the mass of marine salt will be more
+than double the mass of the Himalaya.&mdash;<i>Silliman’s Journal</i>,
+No. 16.</p>
+
+<p>Taking the average depth of the ocean at two miles, and
+its average saltness at 3½ per cent, it appears that there is salt
+enough in the sea to cover to the thickness of one mile an area
+of 7,000,000 of square miles. Admit a transfer of such a quantity
+of matter from an average of half a mile above to one mile
+below the sea-level, and astronomers will show by calculation
+that it would alter the length of the day.</p>
+
+<p>These 7,000,000 of cubic miles of crystal salt have not made
+the sea any fuller.</p>
+
+<h3>PROPERTIES OF SEA-WATER.</h3>
+
+<p>The solid constituents of sea-water amount to about 3½ per
+cent of its weight, or nearly half an ounce to the pound. Its
+saltness is caused as follows: Rivers which are constantly flowing
+into the ocean contain salts varying from 10 to 50, and
+even 100, grains per gallon. They are chiefly common salt,
+sulphate and carbonate of lime, magnesia,<a name="FNanchor_41" id="FNanchor_41" href="#Footnote_41" class="fnanchor">41</a> soda, potash, and
+iron; and these are found to constitute the distinguishing characteristics
+of sea-water. The water which evaporates from the<span class="pagenum"><a name="Page_180" id="Page_180">180</a></span>
+sea is nearly pure, containing but very minute traces of salts.
+Falling as rain upon the land, it washes the soil, percolates
+through the rocky layers, and becomes charged with saline
+substances, which are borne seaward by the returning currents.
+The ocean, therefore, is the great depository of every thing that
+water can dissolve and carry down from the surface of the continents;
+and as there is no channel for their escape, they consequently
+accumulate (<i>Youmans’ Chemistry</i>). They would constantly
+accumulate, as this very shrewd author remarks, were
+it not for the shells and insects of the sea and other agents.</p>
+
+<h3>SCENERY AND LIFE OF THE ARCTIC REGIONS.</h3>
+
+<p>The late Dr. Scoresby, from personal observations made in
+the course of twenty-one voyages to the Arctic Regions, thus
+describes these striking characteristics:</p>
+
+<blockquote>
+
+<p>The coast scenes of Greenland are generally of an abrupt character,
+the mountains frequently rising in triangular profile; so much so, that
+it is sometimes not possible to effect their ascent. One of the most
+notable characteristics of the Arctic lands is the deception to which travellers
+are liable in regard to distances. The occasion of this is the
+quantity of light reflected from the snow, contrasted with the dark colour
+of the rocks. Several persons of considerable experience have been
+deceived in this way, imagining, for example, that they were close to
+the shore when in fact they were more than twenty miles off. The trees
+of these lands are not more than three inches above ground.</p>
+
+<p>Many of the icebergs are five miles in extent, and some are to be
+seen running along the shore measuring as much as thirteen miles. Dr.
+Scoresby has seen a cliff of ice supported on those floating masses 402
+feet in height. There is no place in the world where animal life is to
+be found in greater profusion than in Greenland, Spitzbergen, Baffin’s
+Bay, and other portions of the Arctic regions. This is to be accounted
+for by the abundance and richness of the food supplied by the sea. The
+number of birds is especially remarkable. On one occasion, no less
+than a million of little hawks came in sight of Dr. Scoresby’s ship within
+a single hour.</p>
+
+<p>The various phenomena of the Greenland sea are very interesting.
+The different colours of the sea-water&mdash;olive or bottle-green, reddish-brown,
+and mustard&mdash;have, by the aid of the microscope, been found
+to be owing to animalculæ of these various colours: in a single drop of
+mustard-coloured water have been counted 26,450 animals. Another
+remarkable characteristic of the Greenland sea-water is its warm temperature&mdash;one,
+two, and three degrees above the freezing-point even in
+the cold season. This Dr. Scoresby accounts for by supposing the flow
+in that direction of warm currents from the south. The polar fields of
+ice are to be found from eight or nine to thirty or forty feet in thickness.
+By fastening a hook twelve or twenty inches in these masses of
+ice, a ship could ride out in safety the heaviest gales.</p></blockquote>
+
+<h3>ICEBERG OF THE POLAR SEAS.</h3>
+
+<p>The ice of this berg, although opaque and vascular, is true
+glacier ice, having the fracture, lustre, and other external characters<span class="pagenum"><a name="Page_181" id="Page_181">181</a></span>
+of a nearly homogeneous growth. The iceberg is true
+ice, and is always dreaded by ships. Indeed, though modified
+by climate, and especially by the alternation of day and night,
+the polar glacier must be regarded as strictly atmospheric in
+its increments, and not essentially differing from the glacier of
+the Alps. The general appearance of a berg may be compared
+to frosted silver; but when its fractures are very extensive,
+the exposed faces have a very brilliant lustre. Nothing can be
+more exquisite than a fresh, cleanly fractured berg surface: it
+reminds one of the recent cleavage of sulphate of strontian&mdash;a
+resemblance more striking from the slightly lazulitic tinge of
+each.&mdash;<i>U.&nbsp;S. Grinnel Expedition in Search of Sir J. Franklin.</i></p>
+
+<h3>IMMENSITY OF POLAR ICE.</h3>
+
+<p>The quantity of solid matter that is drifted out of the
+Polar Seas through one opening&mdash;Davis’s Straits&mdash;alone, and
+during a part of the year only, covers to the depth of seven
+feet an area of 300,000 square miles, and weighs not less than
+18,000,000,000 tons. The quantity of water required to float
+and drive out this solid matter is probably many times greater
+than this. A quantity of water equal in weight to these two
+masses has to go in. The basin to receive these inflowing waters,
+<i>i. e.</i> the unexplored basin about the North Pole, includes
+an area of 1,500,000 square miles; and as the outflowing ice
+and water are at the surface, the return current must be submarine.</p>
+
+<p>These two currents, therefore, it may be perceived, keep in
+motion between the temperate and polar regions of the earth a
+volume of water, in comparison with which the mighty Mississippi
+in its greatest floods sinks down to a mere rill.&mdash;<i>Maury.</i></p>
+
+<h3>OPEN SEA AT THE POLE.</h3>
+
+<p>The following fact is striking: In 1662&ndash;3, Mr. Oldenburg,
+Secretary to the Royal Society, was ordered to register a paper
+entitled “Several Inquiries concerning Greenland, answered by
+Mr. Gray, who had visited those parts.” The nineteenth query
+was, “How near any one hath been known to approach the Pole.
+<i>Answer.</i> I once met upon the coast of Greenland a Hollander,
+that swore he had been but half a degree from the Pole, showing
+me his journal, which was also attested by his mate; where
+<i>they had seen no ice or land, but all water</i>.” Boyle mentions
+a similar account, which he received from an old Greenland
+master, on April 5, 1765.</p>
+
+<h3>RIVER-WATER ON THE OCEAN.</h3>
+
+<p>Captain Sabine found discoloured water, supposed to be
+that of the Amazon, 300 miles distant in the ocean from the<span class="pagenum"><a name="Page_182" id="Page_182">182</a></span>
+embouchure of that river. It was about 126 feet deep. Its specific
+gravity was = 1·0204, and the specific gravity of the sea-water
+= 1·0262. This appears to be the greatest distance from
+land at which river-water has been detected on the surface of
+the ocean. It was estimated to be moving at the rate of three
+miles an hour, and had been turned aside by an ocean-current.
+“It is not a little curious to reflect,” says Sir Henry de la Beche,
+“that the agitation and resistance of its particles should be sufficient
+to keep finely comminuted solid matter mechanically
+suspended, so that it would not be disposed freely to part with
+it except at its junction with the sea-water over which it flows,
+and where, from friction, it is sufficiently retarded.”</p>
+
+<h3>THE THAMES AND ITS SALT-WATER BED.</h3>
+
+<p>The Thames below Woolwich, in place of flowing upon a
+solid bottom, really flows upon the liquid bottom formed by
+the water of the sea. At the flow of the tide, the fresh water
+is raised, as it were, in a single mass by the salt water which
+flows in, and which ascends the bed of the river, while the fresh
+water continues to flow towards the sea.&mdash;<i>Mr. Stevenson, in
+Jameson’s Journal.</i></p>
+
+<h3>FRESH SPRINGS IN THE MIDDLE OF THE OCEAN.</h3>
+
+<p>On the southern coast of the island of Cuba, at a few miles
+from land, Springs of Fresh Water gush from the bed of the
+Ocean, probably under the influence of hydrostatic pressure, and
+rise through the midst of the salt water. They issue forth with
+such force that boats are cautious in approaching this locality,
+which has an ill repute on account of the high cross sea thus
+caused. Trading vessels sometimes visit these springs to take
+in a supply of fresh water, which is thus obtained in the open
+sea. The greater the depth from which the water is taken,
+the fresher it is found to be.</p>
+
+<h3>“THE BLACK WATERS.”</h3>
+
+<p>In the upper portion of the basin of the Orinoco and its
+tributaries, Nature has several times repeated the enigmatical
+phenomenon of the so-called “Black Waters.” The Atabapo,
+whose banks are adorned with Carolinias and arborescent Melastomas,
+is a river of a coffee-brown colour. In the shade of
+the palm-groves this colour seems about to pass into ink-black.
+When placed in transparent vessels, the water appears of a golden
+yellow. The image of the Southern Constellation is reflected
+with wonderful clearness in these black streams. When their
+waters flow gently, they afford to the observer, when taking
+astronomical observations with reflecting instruments, a most
+excellent artificial horizon. These waters probably owe their<span class="pagenum"><a name="Page_183" id="Page_183">183</a></span>
+peculiar colour to a solution of carburetted hydrogen, to the
+luxuriance of the tropical vegetation, and to the quantity of
+plants and herbs on the ground over which they flow.&mdash;<i>Humboldt’s
+Aspects of Nature</i>, vol. i.</p>
+
+<h3>GREAT CATARACT IN INDIA.</h3>
+
+<p>Where the river Shirhawti, between Bombay and Cape Comorin,
+falls into the Gulf of Arabia, it is about one-fourth of a
+mile in width, and in the rainy season some thirty feet in depth.
+This immense body of water rushes down a rocky slope 300 feet,
+at an angle of 45°, at the bottom of which it makes a perpendicular
+plunge of 850 feet into a black and dismal abyss, with
+a noise like the loudest thunder. The whole descent is therefore
+1150 feet, or several times that of Niagara; but the volume
+of water in the latter is somewhat larger than in the former.</p>
+
+<h3>CAUSE OF WAVES.</h3>
+
+<p>The friction of the wind combines with the tide in agitating
+the surface of the ocean, and, according to the theory of undulations,
+each produces its effect independently of the other.
+Wind, however, not only raises waves, but causes a transfer of
+superficial water also. Attraction between the particles of air
+and water, as well as the pressure of the atmosphere, brings its
+lower stratum into adhesive contact with the surface of the sea.
+If the motion of the wind be parallel to the surface, there will
+still be friction, but the water will be smooth as a mirror; but
+if it be inclined, in however small a degree, a ripple will appear.
+The friction raises a minute wave, whose elevation protects the
+water beyond it from the wind, which consequently impinges
+on the surface at a small angle: thus each impulse, combining
+with the other, produces an undulation which continually advances.&mdash;<i>Mrs.
+Somerville’s Physical Geography.</i></p>
+
+<h3>RATE AT WHICH WAVES TRAVEL.</h3>
+
+<p>Professor Bache states, as one of the effects of an earthquake
+at Simoda, on the island of Niphon, in Japan, that the harbour
+was first emptied of water, and then came in an enormous wave,
+which again receded and left the harbour dry. This occurred
+several times. The United-States self-acting tide-gauge at San
+Francisco, which records the rise of the tide upon cylinders
+turned by clocks, showed that at San Francisco, 4800 miles from
+the scene of the earthquake, the first wave arrived twelve hours
+and sixteen minutes after it had receded from the harbour of
+Simoda. It had travelled across the broad bosom of the Pacific
+Ocean at the rate of six miles and a half a minute, and arrived
+on the shores of California: the first wave being seven-tenths of<span class="pagenum"><a name="Page_184" id="Page_184">184</a></span>
+a foot in height, and lasting for about half an hour, followed by
+seven lesser waves, at intervals of half an hour each.</p>
+
+<p>The velocity with which a wave travels depends on the depth
+of the ocean. The latest calculations for the Pacific Ocean give
+a depth of from 14,000 to 18,000 fathoms. It is remarkable
+how the estimates of the ocean’s depth have grown less. Laplace
+assumed it at ten miles, Whewell at 3·5, while the above
+estimate brings it down to two miles.</p>
+
+<p>Mr. Findlay states, that the dynamic force exerted by Sea-Waves
+is greatest at the crest of the wave before it breaks; and
+its power in raising itself is measured by various facts. At
+Wasburg, in Norway, in 1820, it rose 400 feet; and on the
+coast of Cornwall, in 1843, 300 feet. The author shows that
+waves have sometimes raised a column of water equivalent to
+a pressure of from three to five tons the square foot. He also
+proves that the velocity of the waves depends on their length,
+and that waves of from 300 to 400 feet in length from crest to
+crest travel from twenty to twenty-seven and a half miles an
+hour. Waves travel great distances, and are often raised by
+distant hurricanes, having been felt simultaneously at St. Helena
+and Ascension, though 600 miles apart; and it is probable
+that ground-swells often originate at the Cape of Good Hope,
+3000 miles distant. Dr. Scoresby found the travelling rate of
+the Atlantic waves to be 32·67 English statute miles per hour.</p>
+
+<p>In the winter of 1856, a heavy ground-swell, brought on by
+five hours’ gale, scoured away in fourteen hours 3,900,000 tons
+of pebbles from the coast near Dover; but in three days, without
+any shift of wind, upwards of 3,000,000 tons were thrown
+back again. These figures are to a certain extent conjectural;
+but the quantities have been derived from careful measurement
+of the profile of the beach.</p>
+
+<h3>OCEAN-HIGHWAYS: HOW SEA-ROUTES HAVE BEEN
+SHORTENED.</h3>
+
+<p>When one looks seaward from the shore, and sees a ship
+disappear in the horizon as she gains an offing on a voyage to
+India, or the Antipodes perhaps, the common idea is that she
+is bound over a trackless waste; and the chances of another
+ship sailing with the same destination the next day, or the
+next week, coming up and speaking with her on the “pathless
+ocean,” would to most minds seem slender indeed. Yet
+the truth is, the winds and the currents are now becoming so
+well understood, that the navigator, like the backwoodsman
+in the wilderness, is enabled literally to “blaze his way” across
+the ocean; not, indeed, upon trees, as in the wilderness, but
+upon the wings of the wind. The results of scientific inquiry<span class="pagenum"><a name="Page_185" id="Page_185">185</a></span>
+have so taught him how to use these invisible couriers, that
+they, with the calm belts of the air, serve as sign-boards to
+indicate to him the turnings and forks and crossings by the
+way.</p>
+
+<blockquote>
+
+<p>Let a ship sail from New York to California, and the next week let
+a faster one follow; they will cross each other’s path many times, and
+are almost sure to see each other by the way, as in the voyage of two
+fine clipper-ships from New York to California. On the ninth day after
+the <i>Archer</i> had sailed, the <i>Flying Cloud</i> put to sea. Both ships were
+running against time, but without reference to each other. The <i>Archer</i>,
+with wind and current charts in hand, went blazing her way across the
+calms of Cancer, and along the new route down through the north-east
+trades to the equator; the <i>Cloud</i> followed, crossing the equator upon
+the trail of Thomas of the <i>Archer</i>. Off Cape Horn she came up with him,
+spoke him, and handed him the latest New York dates. The <i>Flying
+Cloud</i> finally ranged ahead, made her adieus, and disappeared among
+the clouds that lowered upon the western horizon, being destined to
+reach her port a week or more in advance of her Cape Horn consort.
+Though sighting no land from the time of their separation until they
+gained the offing of San Francisco,&mdash;some six or eight thousand miles
+off,&mdash;the tracks of the two vessels were so nearly the same, that being
+projected upon the chart, they appear almost as one.</p>
+
+<p>This is the great course of the ocean: it is 15,000 miles in length.
+Some of the most glorious trials of speed and of prowess that the world
+ever witnessed among ships that “walk the waters” have taken place
+over it. Here the modern clipper-ship&mdash;the noblest work that has ever
+come from the hands of man&mdash;has been sent, guided by the lights of
+science, to contend with the elements, to outstrip steam, and astonish
+the world.&mdash;<i>Maury.</i></p></blockquote>
+
+<h3>ERROR UPON ERROR.</h3>
+
+<p>The great inducement to Mr. Babbage, some years since, to
+attempt the construction of a machine by which astronomical
+tables could be calculated and even printed by mechanical
+means, and with entire accuracy, was the errors in the requisite
+tables. Nineteen such errors, in point of fact, were discovered
+in an edition of Taylor’s <i>Logarithms</i> printed in 1796;
+some of which might have led to the most dangerous results in
+calculating a ship’s place. These nineteen errors (of which one
+only was an error of the press) were pointed out in the <i>Nautical
+Almanac</i> for 1832. In one of these <i>errata</i>, the seat of the
+error was stated to be in cosine of 14° 18′ 3″. Subsequent
+examination showed that there was an error of one second in
+this correction, and accordingly, in the <i>Nautical Almanac</i> of
+the next year a new correction was necessary. But in making
+the new correction of one second, a new error was committed
+of ten degrees, making it still necessary, in some future edition
+of the <i>Nautical Almanac</i>, to insert an <i>erratum</i> in an <i>erratum</i> of
+the <i>errata</i> in Taylor’s <i>Logarithms</i>.&mdash;<i>Edinburgh Review</i>, vol. 59.</p>
+
+<hr />
+
+<p><span class="pagenum"><a name="Page_186" id="Page_186">186</a></span></p>
+
+<div class="chapter"></div>
+<h2><a name="Phenomena" id="Phenomena"></a>Phenomena of Heat.</h2>
+
+<h3>THE LENGTH OF THE DAY AND THE HEAT OF THE EARTH.</h3>
+
+<p>As we may judge of the uniformity of temperature from the
+unaltered time of vibration of a pendulum, so we may also
+learn from the unaltered rotatory velocity of the earth the
+amount of stability in the mean temperature of our globe.
+This is the result of one of the most brilliant applications of
+the knowledge we had long possessed of the movement of the
+heavens to the thermic condition of our planet. The rotatory
+velocity of the earth depends on its volume; and since, by the
+gradual cooling of the mass by radiation, the axis of rotation
+would become shorter, the rotatory velocity would necessarily
+increase, and the length of the day diminish with a decrease of
+the temperature. From the comparison of the secular inequalities
+in the motions of the moon with the eclipses observed in
+former ages, it follows that, since the time of Hipparchus,&mdash;that
+is, for full 2000 years,&mdash;the length of the day has certainly not
+diminished by the hundredth part of a second. The decrease
+of the mean heat of the globe during a period of 2000 years has
+not therefore, taking the extremest limits, diminished as much
+as 1/306th of a degree of Fahrenheit.<a name="FNanchor_42" id="FNanchor_42" href="#Footnote_42" class="fnanchor">42</a>&mdash;<i>Humboldt’s Cosmos</i>, vol. i.</p>
+
+<h3>NICE MEASUREMENT OF HEAT.</h3>
+
+<p>A delicate thermometer, placed on the ground, will be affected
+by the passage of a single cloud across a clear sky; and
+if a succession of clouds pass over, with intervals of clear sky
+between them, such an instrument has been observed to fluctuate
+accordingly, rising with each passing mass of vapour, and
+falling again when the radiation becomes unrestrained.</p>
+
+<h3>EXPENDITURE OF HEAT BY THE SUN.</h3>
+
+<p>Sir John Herschel estimates the total Expenditure of Heat
+by the Sun in a given time, by supposing a cylinder of ice 45
+miles in diameter to be continually darted into the sun <i>with
+the velocity of light</i>, and that the water produced by its fusion
+were continually carried off: the heat now given off constantly<span class="pagenum"><a name="Page_187" id="Page_187">187</a></span>
+by radiation would then be wholly expended in its
+liquefaction, on the one hand, so as to leave no radiant surplus;
+while, on the other, the actual temperature at its surface would
+undergo no diminution.</p>
+
+<p>The great mystery, however, is to conceive how so enormous
+a conflagration (if such it be) can be kept up. Every
+discovery in chemical science here leaves us completely at a
+loss, or rather seems to remove further the prospect of probable
+explanation. If conjecture might be hazarded, we should look
+rather to the known possibility of an indefinite generation of
+heat by friction, or to its excitement by the electric discharge,
+than to any combustion of ponderable fuel, whether solid or
+gaseous, for the origin of the solar radiation.&mdash;<i>Outlines.</i><a name="FNanchor_43" id="FNanchor_43" href="#Footnote_43" class="fnanchor">43</a></p>
+
+<h3>DISTINCTIONS OF HEAT.</h3>
+
+<p>Among the curious laws of modern science are those which
+regulate the transmission of radiant heat through transparent
+bodies. The heat of our fires is intercepted and detained by
+screens of glass, and, being so detained, warms them; while
+solar heat passes freely through and produces no such effect.
+“The more recent researches of Delaroche,” says Sir John Herschel,
+“however, have shown that this detention is complete
+only when the temperature of the source of heat is low; but
+that as the temperature gets higher a portion of the heat radiated
+acquires a power of penetrating glass, and that the
+quantity which does so bears continually a larger and larger proportion
+to the whole, as the heat of the radiant body is more
+intense. This discovery is very important, as it establishes a
+community of nature between solar and terrestrial heat; while
+at the same time it leads us to regard the actual temperature of
+the sun as far exceeding that of any earthly flame.”</p>
+
+<h3>LATENT HEAT.</h3>
+
+<p>This extraordinary principle exists in all bodies, and may
+be pressed out of them. The blacksmith hammers a nail until
+it becomes red hot, and from it he lights the match with which
+he kindles the fire of his forge. The iron has by this process
+become more dense, and percussion will not again produce incandescence
+until the bar has been exposed in fire to a red heat,
+when it absorbs heat, the particles are restored to their former
+state, and we can again by hammering develop both heat and
+light.&mdash;<i>R. Hunt, F.R.S.</i></p>
+
+<p><span class="pagenum"><a name="Page_188" id="Page_188">188</a></span></p>
+
+<h3>HEAT AND EVAPORATION.</h3>
+
+<p>In a communication made to the French Academy, M.
+Daubrée calculates that the Evaporation of the Water on the
+surface of the globe employs a quantity of heat about equal to
+one-third of what is received from the sun; or, in other words,
+equal to the melting of a bed of ice nearly thirty-five feet in
+thickness if spread over the globe.</p>
+
+<h3>HEAT AND MECHANICAL POWER.</h3>
+
+<p>It has been found that Heat and Mechanical Power are
+mutually convertible; and that the relation between them is
+definite, 772 foot-pounds of motive power being equivalent to
+a unit of heat, that is, to the amount of heat requisite to raise a
+pound of water through one degree of Fahrenheit.</p>
+
+<h3>HEAT OF MINES.</h3>
+
+<p>One cause of the great Heat of many of our deep Mines,
+which appears to have been entirely lost sight of, is the chemical
+action going on upon large masses of pyritic matter in their
+vicinity. The heat, which is so oppressive in the United Mines
+in Cornwall that the miners work nearly naked, and bathe in
+water at 80° to cool themselves, is without doubt due to the
+decomposition of immense quantities of the sulphurets of iron
+and copper known to be in this condition at a short distance
+from these mineral works.&mdash;<i>R. Hunt, F.R.S.</i></p>
+
+<h3>VIBRATION OF HEATED METALS.</h3>
+
+<p>Mr. Arthur Trevelyan discovered accidentally that a bar of
+iron, when heated and placed with one end on a solid block
+of lead, in cooling vibrates considerably, and produces sounds
+similar to those of an Æolian harp. The same effect is produced
+by bars of copper, zinc, brass, and bell-metal, when
+heated and placed on blocks of lead, tin, or pewter. The bars
+were four inches long, one inch and a half wide, and three-eighths
+of an inch thick.</p>
+
+<p>The conditions essential to these experiments are, That two
+different metals must be employed&mdash;the one soft and possessed
+of moderate conducting powers, viz. lead or tin, the other hard;
+and it matters not whether soft metal be employed for the bar
+or block, provided the soft metal be cold and the hard metal
+heated.</p>
+
+<p>That the surface of the block shall be uneven, for when rendered
+quite smooth the vibration does not take place; but the
+bar cannot be too smooth.</p>
+
+<p>That no matter be interposed, else it will prevent vibration,<span class="pagenum"><a name="Page_189" id="Page_189">189</a></span>
+with the exception of a burnish of gold leaf, the thickness of
+which cannot amount to the two-hundred-thousandth part of
+an inch.&mdash;<i>Transactions of the Royal Society of Edinburgh.</i></p>
+
+<h3>EXPANSION OF SPIRITS.</h3>
+
+<p>Spirits expand and become lighter by means of heat in a
+greater proportion than water, wherefore they are heaviest in
+winter. A cubic inch of brandy has been found by many experiments
+to weigh ten grains more in winter than in summer,
+the difference being between four drams thirty-two grains and
+four drams forty-two grains. Liquor-merchants take advantage
+of this circumstance, and make their purchases in winter
+rather than in summer, because they get in reality rather a
+larger quantity in the same bulk, buying by measure.&mdash;<i>Notes in
+Various Sciences.</i></p>
+
+<h3>HEAT PASSING THROUGH GLASS.</h3>
+
+<p>The following experiment is by Mr. Fox Talbot: Heat a
+poker bright-red hot, and having opened a window, apply the
+poker quickly very near to the outside of a pane, and the hand
+to the inside; a strong heat will be felt at the instant, which
+will cease as soon as the poker is withdrawn, and may be again
+renewed and made to cease as quickly as before. Now it is
+well known, that if a piece of glass is so much warmed as to
+convey the impression of heat to the hand, it will retain some
+part of that heat for a minute or more; but in this experiment
+the heat will vanish in a moment: it will not, therefore, be the
+heated pane of glass that we shall feel, but heat which has come
+through the glass in a free or radiant state.</p>
+
+<h3>HEAT FROM GAS-LIGHTING.</h3>
+
+<p>In the winter of 1835, Mr. W.&nbsp;H. White ascertained the temperature
+in the City to be 3° higher than three miles south of
+London Bridge; and <i>after the gas had been lighted in the City</i>
+four or five hours the temperature increased full 3°, thus making
+6° difference in the three miles.</p>
+
+<h3>HEAT BY FRICTION.</h3>
+
+<p>Friction as a source of Heat is well known: we rub our
+hands to warm them, and we grease the axles of carriage-wheels
+to prevent their setting fire to the wood. Count Rumford
+has established the extraordinary fact, that an unlimited supply
+of heat may be derived from friction by the same materials:
+he made great quantities of water boil by causing a blunt borer
+to rub against a mass of metal immersed in the water. Savages
+light their fires by rubbing two pieces of wood: the <i>modus operandi</i>,<span class="pagenum"><a name="Page_190" id="Page_190">190</a></span>
+as practised by the Kaffirs of South Africa, is thus described
+by Captain Drayton:</p>
+
+<blockquote>
+
+<p>Two dry sticks, one being of hard and the other of soft wood, were
+the materials used. The soft stick was laid on the ground, and held
+firmly down by one Kaffir, whilst another employed himself in scooping
+out a little hole in the centre of it with the point of his assagy: into this
+little hollow the end of the hard wood was placed, and held vertically.
+These two men sat face to face, one taking the vertical stick between
+the palms of his hands, and making it twist about very quickly, while
+the other Kaffir held the lower stick firmly in its place; the friction
+caused by the end of one piece of wood revolving upon the other soon
+made the two pieces smoke. When the Kaffir who twisted became tired,
+the respective duties were exchanged. These operations having continued
+about a couple of minutes, sparks began to appear, and when they
+became numerous, were gathered into some dry grass, which was then
+swung round at arm’s length until a blaze was established; and a roaring
+fire was gladdening the hearts of the Kaffirs with the anticipation of
+a glorious feast in about ten minutes from the time that the operation
+was first commenced.</p></blockquote>
+
+<h3>HEAT BY FRICTION FROM ICE.</h3>
+
+<p>When Sir Humphry Davy was studying medicine at Penzance,
+one of his constant associates was Mr. Tom Harvey, a
+druggist in the above town. They constantly experimented together;
+and one severe winter’s day, after a discussion on the
+nature of heat, the young philosophers were induced to go to
+Larigan river, where Davy succeeded in developing heat by <i>rubbing
+two pieces of ice together</i> so as to melt each other;<a name="FNanchor_44" id="FNanchor_44" href="#Footnote_44" class="fnanchor">44</a> an experiment
+which he repeated with much <i>éclat</i> many years after,
+in the zenith of his celebrity, at the Royal Institution. The
+pieces of ice for this experiment are fastened to the ends of two
+sticks, and rubbed together in air below the temperature of
+32°: this Davy readily accomplished on the day of severe cold
+at the Larigan river; but when the experiment was repeated at
+the Royal Institution, it was in the vacuum of an air-pump,
+when the temperature of the apparatus and of the surrounding
+air was below 32°. It was remarked, that when the surface
+of the rubbing pieces was rough, only half as much heat was
+evolved as when it was smooth. When the pressure of the rubbing
+piece was increased four times, the proportion of heat
+evolved was increased sevenfold.</p>
+
+<h3>WARMING WITH ICE.</h3>
+
+<p>In common language, any thing is understood to be cooled
+or warmed when the temperature thereof is made higher or
+lower, whatever may have been the temperature when the
+change was commenced. Thus it is said that melted iron is<span class="pagenum"><a name="Page_191" id="Page_191">191</a></span>
+<i>cooled</i> down to a sub-red heat, or mercury is cooled from the
+freezing point to zero, or far below. By the same rule, solid
+mercury, say 50° below zero, may, in any climate or temperature
+of the atmosphere, be immediately warmed and melted by
+being imbedded in a cake of ice.&mdash;<i>Scientific American.</i></p>
+
+<h3>REPULSION BY HEAT.</h3>
+
+<p>If water is poured upon an iron sieve, the wires of which
+are made red-hot, it will not run through; but on cooling, it
+will pass through rapidly. M. Boutigny, pursuing this curious
+inquiry, has proved that the moisture upon the skin is sufficient
+to protect it from disorganisation if the arm is plunged into
+baths of melted metal. The resistance of the surfaces is so great
+that little elevation of temperature is experienced. Professor
+Plücker has stated, that by washing the arm with ether previously
+to plunging it into melted metal, the sensation produced
+while in the molten mass is that of freezing coldness.&mdash;<i>R.
+Hunt, F.R.S.</i></p>
+
+<h3>PROTECTION FROM INTENSE HEAT.</h3>
+
+<p>The singular power which the body possesses of resisting
+great heats, and of breathing air of high temperatures, has at
+various times excited popular wonder. In the last century
+some curious experiments were made on this subject. Sir
+Joseph Banks, Dr. Solander, and Sir Charles Blagden, entered
+a room in which the air had a temperature of 198° Fahr., and
+remained ten minutes. Subsequently they entered the room
+separately, when Dr. Solander found the heat 210°, and Sir
+Joseph 211°, whilst their bodies preserved their natural degree
+of heat. Whenever they breathed upon a thermometer, it sank
+several degrees; every inspiration gave coolness to their nostrils,
+and their breath cooled their fingers when it reached them. Sir
+Charles Blagden entered an apartment when the heat was 1°
+or 2° above 260°, and remained eight minutes, mostly on the
+coolest spot, where the heat was above 240°. Though very hot,
+Sir Charles felt no pain: during seven minutes his breathing
+was good; but he then felt an oppression in his lungs, and his
+pulse was 144, double its ordinary quickness. To prove the
+heat of the room, eggs and a beefsteak were placed upon a tin
+frame near the thermometer, when in twenty minutes the eggs
+were roasted hard, and in forty-seven minutes the steak was
+dressed dry; and when the air was put in motion by a pair of
+bellows upon another steak, part of it was well done in thirteen
+minutes. It is remarkable, that in these experiments the same
+person who experienced no inconvenience from air heated to
+211°, could just bear rectified spirits of wine at 130°, cooling oil
+at 129°, cooling water at 123°, and cooling quicksilver at 117°.</p>
+
+<p><span class="pagenum"><a name="Page_192" id="Page_192">192</a></span>
+Sir Francis Chantrey, the sculptor, however, exposed himself
+to a temperature still higher than any yet mentioned, as described
+by Sir David Brewster:</p>
+
+<blockquote>
+
+<p>The furnace which he employs for drying his moulds is about fourteen
+feet long, twelve feet high, and twelve feet broad. When it is raised to
+its highest temperature, with the doors closed, the thermometer stands
+at 350°, and the iron floor is red-hot. The workmen often enter it at
+a temperature of 340°, walking over the iron floor with wooden clogs,
+which are of course charred on the surface. On one occasion, Mr. Chantrey,
+accompanied by five or six of his friends, entered the furnace; and
+after remaining two minutes they brought out a thermometer which
+stood at 320°. Some of the party experienced sharp pains in the tips
+of their ears and in the septum of the nose, while others felt a pain in
+their eyes.&mdash;<i>Natural Magic</i>, 1833.</p></blockquote>
+
+<p>In some cases the clothing worn by the experimenters conducts
+away the heat. Thus, in 1828, a Spaniard entered a heated
+oven, at the New Tivoli, near Paris; he sang a song while a
+fowl was roasted by his side, he then ate the fowl and drank a
+bottle of wine, and on coming out his pulse beat 176°, and the
+thermometer was at 110° Reaumur. He then stretched himself
+upon a plank in the oven surrounded by lighted candles,
+when the mouth of the oven was closed; he remained there
+five minutes, and on being taken out, all the candles were extinguished
+and melted, and the Spaniard’s pulse beat 200°.
+Now much of the surprise ceases when it is added that he
+wore wide woollen pantaloons, a loose mantle of wool, and a
+great quilted cap; the several materials of this clothing being
+bad conductors of heat.</p>
+
+<p>In 1829 M. Chabert, the “Fire-King,” exhibited similar
+feats at the Argyll Rooms in Regent Street. He first swallowed
+forty grains of phosphorus, then two spoonfuls of oil at
+330°, and next held his head over the fumes of sulphuric acid.
+He had previously provided himself with an antidote for the
+poison of the phosphorus. Dressed in a loose woollen coat, he
+then entered a heated oven, and in five minutes cooked two
+steaks; he then came out of the oven, when the thermometer
+stood at 380°. Upon another occasion, at White Conduit House,
+some of his feats were detected.</p>
+
+<p>The scientific secret is as follows: Muscular tissue is an
+extremely bad conductor; and to this in a great measure the
+constancy of the temperature of the human body in various
+zones is to be attributed. To this fact also Sir Charles Blagden
+and Chantrey owed their safety in exposing their bodies to
+a high temperature; from the almost impervious character of
+the tissues of the body, the irritation produced was confined to
+the surface.</p>
+
+<hr />
+
+<p><span class="pagenum"><a name="Page_193" id="Page_193">193</a></span></p>
+
+<div class="chapter"></div>
+<h2><a name="Magnetism" id="Magnetism"></a>Magnetism and Electricity.</h2>
+
+<h3>MAGNETIC HYPOTHESES.</h3>
+
+<p>As an instance of the obstacles which erroneous hypotheses
+throw in the way of scientific discovery, Professor Faraday adduces
+the unsuccessful attempts that had been made in England
+to educe Magnetism from Electricity until Oersted showed
+the simple way. Faraday relates, that when he came to the
+Royal Institution as an assistant in the laboratory, he saw
+Davy, Wollaston, and Young trying, by every way that suggested
+itself to them, to produce magnetic effects from an electric
+current; but having their minds diverted from the true
+course by their existing hypotheses, it did not occur to them
+to try the effect of holding a wire through which an electric
+current was passing over a suspended magnetic needle. Had
+they done so, as Oersted afterwards did, the immediate deflection
+of the needle would have proved the magnetic property
+of an electric current. Faraday has shown that the magnetism
+of a steel bar is caused by the accumulated action of all the
+particles of which it is composed: this he proves by first magnetising
+a small steel bar, and then breaking it successively
+into smaller and smaller pieces, each one of which possesses a
+separate pole; and the same operation may be continued until
+the particles become so small as not to be distinguishable without
+a microscope.</p>
+
+<p>We quote the above from a late Number of the <i>Philosophical
+Magazine</i>, wherein also we find the following noble tribute to
+the genius and public and private worth of Faraday:</p>
+
+<blockquote>
+
+<p>The public never can know and appreciate the national value of such
+a man as Faraday. He does not work to please the public, nor to win
+its guineas; and the said public, if asked its opinion as to the practical
+value of his researches, can see no possible practical issue there. The
+public does not know that we need prophets more than mechanics in
+science,&mdash;inspired men, who, by patient self-denial and the exercise of
+the high intellectual gifts of the Creator, bring us intelligence of His
+doings in Nature. To them their pursuits are good in themselves. Their
+chief reward is the delight of being admitted into communion with Nature,
+the pleasure of tracing out and proclaiming her laws, wholly forgetful
+whether those laws will ever augment our banker’s account or
+improve our knowledge of cookery. <i>Such men, though not honoured by
+the title of “practical,” are they which make practical men possible.</i> They
+bring us the tamed forces of Nature, and leave it to others to contrive
+the machinery to which they may be yoked. If we are rightly informed,
+it was Faradaic electricity which shot the glad tidings of the fall of Sebastopol
+from Balaklava to Varna. Had this man converted his talent<span class="pagenum"><a name="Page_194" id="Page_194">194</a></span>
+to commercial purposes, as so many do, we should not like to set a limit
+to his professional income. The quality of his services cannot be expressed
+by pounds; but that brave body, which for forty years has been
+the instrument of that great soul, is a fit object for a nation’s care, as
+the achievements of the man are, or will one day be, the object of a
+nation’s pride and gratitude.</p></blockquote>
+
+<h3>THE CHINESE AND THE MAGNETIC NEEDLE.</h3>
+
+<p>More than a thousand years before our era, a people living
+in the extremest eastern portions of Asia had magnetic carriages,
+on which the movable arm of the figure of a man continually
+pointed to the south, as a guide by which to find the
+way across the boundless grass-plains of Tartary; nay, even in
+the third century of our era, therefore at least 700 years before
+the use of the mariner’s compass in European seas, Chinese
+vessels navigated the Indian Ocean under the direction of
+Magnetic Needles pointing to the south.</p>
+
+<blockquote>
+
+<p>Now the Western nations, the Greeks and the Romans, knew that
+magnetism could be communicated to iron, and <i>that that metal</i> would
+retain it for a length of time. The great discovery of the terrestrial
+directive force depended, therefore, alone on this&mdash;that no one in the
+West had happened to observe an elongated fragment of magnetic iron-stone,
+or a magnetic iron rod, floating by the aid of a piece of wood in
+water, or suspended in the air by a thread, in such a position as to admit
+of free motion.&mdash;<i>Humboldt’s Cosmos</i>, vol. i.</p></blockquote>
+
+<h3>KIRCHER’S “MAGNETISM.”</h3>
+
+<p>More than two centuries since, Athanasius Kircher published
+his strange book on Magnetism, in which he anticipated
+the supposed virtue of magnetic traction in the curative art,
+and advocated the magnetism of the sun and moon, of the
+divining-rod, and showed his firm belief in animal magnetism.
+“In speaking of the vegetable world,” says Mr. Hunt, “and
+the remarkable processes by which the leaf, the flower, and the
+fruit are produced, this sage brings forward the fact of the
+diamagnetic (repelled by the magnet) character of the plant
+which was in 1852 rediscovered; and he refers the motions of
+the sunflower, the closing of the convolvulus, and the directions
+of the spiral formed by the twining plants, to this particular
+influence.”<a name="FNanchor_45" id="FNanchor_45" href="#Footnote_45" class="fnanchor">45</a> Nor were Kircher’s anticipations random
+guesses, but the result of deductions from experiment and observation;
+and the universality of magnetism is now almost
+recognised by philosophers.</p>
+
+<h3>MINUTE MEASUREMENT OF TIME.</h3>
+
+<p>By observing the magnet in the highly-convenient and delicate
+manner introduced by Gauss and Weber, which consists<span class="pagenum"><a name="Page_195" id="Page_195">195</a></span>
+in attaching a mirror to the magnet and determining the constant
+factor necessary to convert the differences of oscillation
+into differences of time, Professor Helmholtz has been able,
+with comparatively simple apparatus, to make accurate determinations
+up to the 1/10000th part of a second.</p>
+
+<h3>POWER OF A MAGNET.</h3>
+
+<p>The Power of a Magnet is estimated by the weight its poles
+are able to carry. Each pole singly is able to support a smaller
+weight than when they both act together by means of a keeper,
+for which reason horse-shoe magnets are superior to bar magnets
+of similar dimensions and character. It has further been
+ascertained that small magnets have a much greater relative
+force than large ones.</p>
+
+<p>When magnetism is excited in a piece of steel in the ordinary
+mode, by friction with a magnet, it would seem that its
+inductive power is able to overcome the coercive power of the
+steel only to a certain depth below the surface; hence we see
+why small pieces of steel, especially if not very hard, are able
+to carry greater relative weights than large magnets. Sir Isaac
+Newton wore in a ring a magnet weighing only 3 grains, which
+would lift 760 grains, <i>i. e.</i> 250 times its own weight.</p>
+
+<p>Bar-magnets are seldom found capable of carrying more
+than their own weight; but horse-shoe magnets of similar steel
+will bear considerably more. Small ones of from half an ounce
+to 1 ounce in weight will carry from 30 to 40 times their own
+weight; while such as weigh from 1 to 2 lbs. will rarely carry
+more than from 10 to 15 times their weight. The writer found
+a 1 lb. horse-shoe magnet that he impregnated by means of the
+feeder able to bear 26½ times its own weight; and Fischer, having
+adopted the like mode of magnetising the steel, which he
+also carefully heated, has made magnets of from 1 to 3 lbs.
+weight that would carry 30 times, and others of from 4 to 6 lbs.
+weight that would carry 20 times, their own weight.&mdash;<i>Professor
+Peschel.</i></p>
+
+<h3>HOW ARTIFICIAL MAGNETS ARE MADE.</h3>
+
+<p>In 1750, Mr. Canton, F.R.S., “one of the most successful
+experimenters in the golden age of electricity,”<a name="FNanchor_46" id="FNanchor_46" href="#Footnote_46" class="fnanchor">46</a> communicated
+to the Royal Society his “Method of making Artificial Magnets
+without the use of natural ones.” This he effected by
+using a poker and tongs to communicate magnetism to steel
+bars. He derived his first hint from observing them one evening,
+as he was sitting by the fire, to be nearly in the same direction
+with the earth as the dipping needle. He thence concluded
+that they must, from their position and the frequent<span class="pagenum"><a name="Page_196" id="Page_196">196</a></span>
+blows they receive, have acquired some magnetic virtue, which
+on trial he found to be the case; and therefore he employed
+them to impregnate his bars, instead of having recourse to the
+natural loadstone. Upon the reading of the above paper, Canton
+exhibited to the Royal Society his experiments, for which
+the Copley Medal was awarded to him in 1751.</p>
+
+<p>Canton had, as early as 1747, turned his attention, with
+complete success, to the production of powerful artificial magnets,
+principally in consequence of the expense of procuring
+those made by Dr. Gowan Knight, who kept his process secret.
+Canton for several years abstained from communicating his
+method even to his most intimate friends, lest it might be
+injurious to Dr. Knight, who procured considerable pecuniary
+advantages by touching needles for the mariner’s compass.</p>
+
+<p>At length Dr. Knight’s method of making artificial magnets
+was communicated to the world by Mr. Wilson, in a paper
+published in the 69th volume of the <i>Philosophical Transactions</i>.
+He provided himself with a large quantity of clean iron-filings,
+which he put into a capacious tub about half full of clear
+water; he then agitated the tub to and fro for several hours,
+until the filings were reduced by attrition to an almost impalpable
+powder. This powder was then dried, and formed
+into paste by admixture with linseed-oil. The paste was then
+moulded into convenient shapes, which were exposed to a moderate
+heat until they had attained a sufficient degree of hardness.</p>
+
+<blockquote>
+
+<p>After allowing them to remain for some time in this state, Dr.
+Knight gave them their magnetic virtue in any direction he pleased,
+by placing them between the extreme ends of his large magazine of
+artificial magnets for a second or more, as he saw occasion. By this
+method the virtue they acquired was such, that when any one of these
+pieces was held between two of his best ten-guinea bars, with its poles
+purposely inverted, it immediately of itself turned about to recover its
+natural direction, which the force of those very powerful bars was not
+sufficient to counteract.</p></blockquote>
+
+<p>Dr. Knight’s powerful battery of magnets above mentioned
+is in the possession of the Royal Society, having been presented
+by Dr. John Fothergill in 1776.</p>
+
+<h3>POWER OF THE SUN’S RAYS IN INCREASING THE STRENGTH
+OF MAGNETS.</h3>
+
+<p>Professor Barlocci found that an armed natural loadstone,
+which would carry 1½ Roman pounds, had its power nearly
+<i>doubled</i> by twenty-four hours’ exposure to the strong light of
+the sun. M. Zantedeschi found that an artificial horse-shoe
+loadstone, which carried 13½ oz., carried 3½ more by three days’
+exposure, and at last arrived to 31 oz. by continuing it in the
+sun’s light. He found that while the strength increased in<span class="pagenum"><a name="Page_197" id="Page_197">197</a></span>
+oxidated magnets, it diminished in those which were not oxidated,
+the diminution becoming insensible when the loadstone
+was highly polished. He now concentrated the solar rays upon
+the loadstone by means of a lens; and he found that, both in
+oxidated and polished magnets, they <i>acquire</i> strength when
+their <i>north</i> pole is exposed to the sun’s rays, and <i>lose</i> strength
+when the <i>south</i> pole is exposed.&mdash;<i>Sir David Brewster.</i></p>
+
+<h3>COLOUR OF A BODY AND ITS MAGNETIC PROPERTIES.</h3>
+
+<p>Solar rays bleach dead vegetable matter with rapidity, while
+in living parts of plants their action is frequently to strengthen
+the colour. Their power is perhaps best seen on the sides of
+peaches, apples, &amp;c., which, exposed to a midsummer’s sun,
+become highly coloured. In the open winter of 1850, Mr. Adie,
+of Liverpool, found in a wallflower plant proof of a like effect:
+in the dark months there was a slow succession of one or two
+flowers, of uniform pale yellow hue; in March streaks of a
+darker colour appeared on the flowers, and continued to slowly
+increase till in April they were variegated brown and yellow,
+of rich strong colours. On the supposition that these changes
+are referable to magnetic properties, may hereafter be explained
+Mrs. Somerville’s experiments on steel needles exposed to the
+sun’s rays under envelopes of silk of various colours; the magnetisation
+of steel needles has failed in the coloured rays of the
+spectrum, but Mr. Adie considers that under dyed silk the effect
+will hinge on the chemical change wrought in the silk and
+its dye by the solar rays.</p>
+
+<h3>THE ONION AND MAGNETISM.</h3>
+
+<p>A popular notion has long been current, more especially on
+the shores of the Mediterranean, that if a magnetic rod be
+rubbed with an onion, or brought in contact with the emanations
+of the plant, the directive force will be diminished, while
+a compass thus treated will mislead the steersman. It is difficult
+to conceive what could have given rise to so singular a
+popular error.<a name="FNanchor_47" id="FNanchor_47" href="#Footnote_47" class="fnanchor">47</a>&mdash;<i>Humboldt’s Cosmos</i>, vol. v.</p>
+
+<h3>DECLINATION OF THE NEEDLE&mdash;THE EARTH A MAGNET.</h3>
+
+<p>The Inclination or Dip of the Needle was first recorded by
+Robert Norman, in a scarce book published in 1576 entitled <i>The
+New Attractive; containing a short Discourse of the Magnet or
+Loadstone, &amp;c.</i></p>
+
+<p>Columbus has not only the merit of being the first to discover
+<i>a line without magnetic variation</i>, but also of having first<span class="pagenum"><a name="Page_198" id="Page_198">198</a></span>
+excited a taste for the study of terrestrial magnetism in Europe,
+by means of his observations on the progressive increase of
+western declination in receding from that line.</p>
+
+<p>The first chart showing the variation of the compass,<a name="FNanchor_48" id="FNanchor_48" href="#Footnote_48" class="fnanchor">48</a> or
+the declination of the needle, based on the idea of employing
+curves drawn through points of equal declination, is due to
+Halley, who is justly entitled the father and founder of terrestrial
+magnetism. And it is curious to find that in No. 195 of
+the <i>Philosophical Transactions</i>, in 1683, Halley had previously
+expressed his belief that he has put it past doubt that the
+globe of the earth is one great magnet, having four magnetical
+poles or points of attraction, near each pole of the equator two;
+and that in those parts of the world which lie near adjacent to
+any one of those magnetical poles, the needle is chiefly governed
+thereby, the nearest pole being always predominant
+over the more remote.</p>
+
+<p>“To Halley” (says Sir John Herschel) “we owe the first appreciation
+of the real complexity of the subject of magnetism.
+It is wonderful indeed, and a striking proof of the penetration
+and sagacity of this extraordinary man, that with his means of
+information he should have been able to draw such conclusions,
+and to take so large and comprehensive a view of the subject
+as he appears to have done.”</p>
+
+<p>And, in our time, “the earth is a great magnet,” says
+Faraday: “its power, according to Gauss, being equal to that
+which would be conferred if every cubic yard of it contained
+six one-pound magnets; the sum of the force is therefore equal
+to 8,464,000,000,000,000,000,000 such magnets.”</p>
+
+<h3>THE AURORA BOREALIS.</h3>
+
+<p>Halley, upon his return from his voyage to verify his theory
+of the variation of the compass, in 1700, hazarded the conjecture
+that the Aurora Borealis is a magnetic phenomenon. And
+Faraday’s brilliant discovery of the evolution of light by magnetism
+has raised Halley’s hypothesis, enounced in 1714, to
+the rank of an experimental certainty.</p>
+
+<h3>EFFECT OF LIGHT ON THE MAGNET.</h3>
+
+<p>In 1854, Sir John Ross stated to the British Association, in
+proof of the effect of every description of light on the magnet,
+that during his last voyage in the <i>Felix</i>, when frozen in about
+one hundred miles north of the magnetic pole, he concentrated<span class="pagenum"><a name="Page_199" id="Page_199">199</a></span>
+the rays of the full moon on the magnetic needle, when he found
+it was five degrees attracted by it.</p>
+
+<h3>MAGNETO-ELECTRICITY.</h3>
+
+<p>In 1820, the Copley Medal was adjudicated to M. Oersted
+of Copenhagen, “when,” says Dr. Whewell, “the philosopher
+announced that the conducting-wire of a voltaic circuit acts
+upon a magnetic needle; and thus recalled into activity that
+endeavour to connect magnetism with electricity which, though
+apparently on many accounts so hopeful, had hitherto been attended
+with no success. Oersted found that the needle has a
+tendency to place itself at <i>right angles</i> to the wire; a kind of
+action altogether different from any which had been suspected.”</p>
+
+<h3>ELECTRO-MAGNETS OF THE HORSE-SHOE FORM</h3>
+
+<p class="in0">were discovered by Sturgeon in 1825. Of two Magnets made by
+a process devised by M. Elias, and manufactured by M. Logemeur
+at Haerlem, one, a single horse-shoe magnet weighing
+about 1 lb., lifts 28½ lbs.; the other, a triple horse-shoe magnet
+of about 10 lbs. weight, is capable of lifting about 150 lbs. Similar
+magnets are made by the same person capable of supporting
+5 cwt. In the process of making them, a helix of
+copper and a galvanic battery are used. The smaller magnet
+has twice the power expressed by Haecker’s formula for the
+best artificial steel magnet.</p>
+
+<p>Subsequently Henry and Ten Eyk, in America, constructed
+some electro-magnets on a large scale. One horse-shoe magnet
+made by them, weighing 60 lbs., would support more than
+2000 lbs.</p>
+
+<p>In September 1858, there were constructed for the Atlantic-telegraph
+cable at Valentia two permanent magnets, from
+which the electric induction is obtained: each is composed of
+30 horse-shoe magnets, 2½ feet long and from 4 to 5 inches
+broad; the induction coils attached to these each contain six
+miles of wire, and a shock from them, if passed through the
+human body, would be sufficient to destroy life.</p>
+
+<h3>ROTATION-MAGNETISM.</h3>
+
+<p>The unexpected discovery of Rotation-Magnetism by Arago,
+in 1825, has shown practically that every kind of matter is susceptible
+of magnetism; and the recent investigations of Faraday
+on diamagnetic substances have, under special conditions
+of meridian or equatorial direction, and of solid, fluid, or gaseous
+inactive conditions of the bodies, confirmed this important result.</p>
+
+<p><span class="pagenum"><a name="Page_200" id="Page_200">200</a></span></p>
+
+<h3>INFLUENCE OF PENDULUMS ON EACH OTHER.</h3>
+
+<p>About a century since it became known, that when two
+clocks are in action upon the same shelf, they will disturb each
+other: that the pendulum of the one will stop that of the other;
+and that the pendulum that was stopped will after a while resume
+its vibrations, and in its turn stop that of the other clock.
+When two clocks are placed near one another in cases very
+slightly fixed, or when they stand on the boards of a floor, they
+will affect a little each other’s pendulum. Mr. Ellicote observed
+that two clocks resting against the same rail, which agreed to a
+second for several days, varied one minute thirty-six seconds in
+twenty-four hours when separated. The slower, having a longer
+pendulum, set the other in motion in 16-1/3 minutes, and stopped
+itself in 36-2/3 minutes.</p>
+
+<h3>WEIGHT OF THE EARTH ASCERTAINED BY THE PENDULUM.</h3>
+
+<p>By a series of comparisons with Pendulums placed at the
+surface and the interior of the Earth, the Astronomer-Royal has
+ascertained the variation of gravity in descending to the bottom
+of a deep mine, as the Harton coal-pit, near South Shields. By
+calculations from these experiments, he has found the mean
+density of the earth to be 6·566, the specific gravity of water
+being represented by unity. In other words, it has been ascertained
+by these experiments that if the earth’s mass possessed
+every where its average density, it would weigh, bulk for bulk,
+6·566 times as much as water. It is curious to note the different
+values of the earth’s mean density which have been
+obtained by different methods. The Schehallien experiment
+indicated a mean density equal to about 4½; the Cavendish
+apparatus, repeated by Baily and Reich, about 5½; and Professor
+Airy’s pendulum experiment furnishes a value amounting
+to about 6½.</p>
+
+<p>The immediate result of the computations of the Astronomer-Royal
+is: supposing a clock adjusted to go true time at
+the top of the mine, it would gain 2¼ seconds per day at the
+bottom. Or it may be stated thus: that gravity is greater at
+the bottom of a mine than at the top by 1/19190th part.&mdash;<i>Letter to
+James Mather, Esq., South Shields.</i> See also <i>Professor Airy’s Lecture</i>,
+1854.</p>
+
+<h3>ORIGIN OF TERRESTRIAL MAGNETISM.</h3>
+
+<p>The earliest view of Terrestrial Magnetism supposed the existence
+of a magnet at the earth’s centre. As this does not accord
+with the observations on declination, inclination, and intensity,
+Tobias Meyer gave this fictitious magnet an eccentric
+position, placing it one-seventh part of the earth’s radius from
+the centre. Hansteen imagined that there were two such magnets,<span class="pagenum"><a name="Page_201" id="Page_201">201</a></span>
+different in position and intensity. Ampère set aside these
+unsatisfactory hypotheses by the view, derived from his discovery,
+that the earth itself is an electro-magnet, magnetised by an
+electric current circulating about it from east to west perpendicularly
+to the plane of the magnetic meridian, to which the
+same currents give direction as well as magnetise the ores of
+iron: the currents being thermo-electric currents, excited by the
+action of the sun’s heat successively on the different parts of the
+earth’s surface as it revolves towards the east.</p>
+
+<p>William Gilbert,<a name="FNanchor_49" id="FNanchor_49" href="#Footnote_49" class="fnanchor">49</a> who wrote an able work on magnetic and
+electric forces in the year 1600, regarded terrestrial magnetism
+and electricity as two emanations of a single fundamental source
+pervading all matter, and he therefore treated of both at once.
+According to Gilbert’s idea, the earth itself is a magnet; whilst
+he considered that the inflections of the lines of equal declination
+and inclination depend upon the distribution of mass, the
+configuration of continents, or the form and extent of the deep
+intervening oceanic basins.</p>
+
+<p>Till within the last eighty years, it appears to have been the
+received opinion that the intensity of terrestrial magnetism was
+the same at all parts of the earth’s surface. In the instructions
+drawn up by the French Academy for the expedition under La
+Pérouse, the first intimation is given of a contrary opinion. It
+is recommended that the time of vibration of a dipping-needle
+should be observed at stations widely remote, as a test of the
+equality or difference of the magnetic intensity; suggesting also
+that such observations should particularly be made at those parts
+of the earth where the dip was greatest and where it was least.
+The experiments, whatever their results may have been, which,
+in compliance with this recommendation, were made in the expedition
+of La Pérouse, perished in its general catastrophe; but
+the instructions survived.</p>
+
+<p>In 1811, Hansteen took up the subject, and in 1819 published
+his celebrated work, clearly demonstrating the fluctuations
+which this element has undergone during the last two
+centuries; confirming in great detail the position of Halley,
+that “the whole magnetic system is in motion, that the moving
+force is very great as extending its effects from pole to pole,
+and that its motion is not <i>per saltum</i>, but a gradual and regular
+motion.”</p>
+
+<h3>THE NORTH AND SOUTH MAGNETIC POLES.</h3>
+
+<p>The knowledge of the geographical position of both Magnetic
+Poles is due to the scientific energy of the same navigator,<span class="pagenum"><a name="Page_202" id="Page_202">202</a></span>
+Sir James Ross. His observations of the Northern Magnetic
+Pole were made during the second expedition of his uncle,
+Sir John Ross (1829&ndash;1833); and of the Southern during the
+Antarctic expedition under his own command (1839&ndash;1843). The
+Northern Magnetic Pole, in 70° 5′ lat., 96° 43′ W. long., is 5° of
+latitude farther from the ordinary pole of the earth than the
+Southern Magnetic Pole, 75° 35′ lat., 154° 10′ E. long.; whilst
+it is also situated farther west from Greenwich than the Northern
+Magnetic Pole. The latter belongs to the great island of
+Boothia Felix, which is situated very near the American continent,
+and is a portion of the district which Captain Parry had
+previously named North Somerset. It is not far distant from
+the western coast of Boothia Felix, near the promontory of Adelaide,
+which extends into King William’s Sound and Victoria
+Strait.</p>
+
+<p>The Southern Magnetic Pole has been directly reached in
+the same manner as the Northern Pole. On 17th February
+1841, the <i>Erebus</i> penetrated as far as 76° 12′ S. lat., and 164°
+E. long. As the inclination was here only 88° 40′, it was assumed
+that the Southern Magnetic Pole was about 160 nautical miles
+distant. Many accurate observations of declination, determining
+the intersection of the magnetic meridian, render it very
+probable that the South Magnetic Pole is situated in the interior
+of the great Antarctic region of South Victoria Land, west
+of the Prince Albert mountains, which approach the South Pole
+and are connected with the active volcano of Erebus, which is
+12,400 feet in height.&mdash;<i>Humboldt’s Cosmos</i>, vol. v.</p>
+
+<h3>MAGNETIC STORMS.</h3>
+
+<p>The mysterious course of the magnetic needle is equally affected
+by time and space, by the sun’s course, and by changes
+of place on the earth’s surface. Between the tropics the hour
+of the day may be known by the direction of the needle as well
+as by the oscillations of the barometer. It is affected instantly,
+but transiently, by the northern light.</p>
+
+<p>When the uniform horary motion of the needle is disturbed
+by a magnetic storm, the perturbation manifests itself <i>simultaneously</i>,
+in the strictest sense of the word, over hundreds and
+thousands of miles of sea and land, or propagates itself by degrees
+in short intervals every where over the earth’s surface.</p>
+
+<p>Among numerous examples of perturbations occurring simultaneously
+and extending over wide portions of the earth’s surface,
+one of the most remarkable is that of September 25th, 1841,
+which was observed at Toronto in Canada, at the Cape of Good
+Hope, at Prague, and partially in Van Diemen’s Land. Sabine
+adds, “The English Sunday, on which it is deemed sinful,
+after midnight on Saturday, to register an observation, and<span class="pagenum"><a name="Page_203" id="Page_203">203</a></span>
+to follow out the great phenomena of creation in their perfect
+development, interrupted the observation in Van Diemen’s Land,
+where, in consequence of the difference of the longitude, the
+magnetic storm fell on Sunday.”</p>
+
+<blockquote>
+
+<p>It is but justice to add, that to the direct instrumentality of the British
+Association we are indebted for this system of observation, which
+would not have been possible without some such machinery for concerted
+action. It being known that the magnetic needle is subject to oscillations,
+the nature, the periods, and the laws of which were unascertained,
+under the direction of a committee of the Association <i>magnetic observatories</i>
+were established in various places for investigating these strange
+disturbances. As might have been anticipated, regularly recurring perturbations
+were noted, depending on the hour of the day and the season
+of the year. Magnetic storms were observed to sweep simultaneously over
+the whole face of the earth, and these too have now been ascertained to
+follow certain periodic laws.</p>
+
+<p>But the most startling result of the combined magnetic observations
+is the discovery of marked perturbations recurring at intervals of ten
+years; a period which seemed to have no analogy to any thing in the
+universe, but which M. Schwabe has found to correspond with the variation
+of the spots on the sun, both attaining their maximum and minimum
+developments at the same time. Here, for the present, the discovery
+stops; but that which is now an unexplained coincidence may
+hereafter supply the key to the nature and source of Terrestrial Magnetism:
+or, as Dr. Lloyd observes, this system of magnetic observation
+has gone beyond our globe, and opened a new range for inquiry, by
+showing us that this wondrous agent has power in other parts of the
+solar system.</p></blockquote>
+
+<h3>FAMILIAR GALVANIC EFFECTS.</h3>
+
+<p>By means of the galvanic agency a variety of surprising
+effects have been produced. Gunpowder, cotton, and other inflammable
+substances have been set on fire; charcoal has been
+made to burn with a brilliant white flame; water has been decomposed
+into its elementary parts; metals have been melted
+and set on fire; fragments of diamond, charcoal, and plumbago
+have been dispersed as if evaporated; platina, the hardest and
+the heaviest of the metals, has been melted as readily as wax
+in the flame of a candle; the sapphire, quartz, magnesia, lime,
+and the firmest compounds in nature, have been fused. Its
+effects on the animal system are no less surprising.</p>
+
+<p>The agency of galvanism explains why porter has a different
+and more pleasant taste when drunk out of a pewter-pot than
+out of glass or earthenware; why works of metal which are
+soldered together soon tarnish in the place where the metals are
+joined; and why the copper sheathing of ships, when fastened
+with iron nails, is soon corroded about the place of contact. In
+all these cases a galvanic circle is formed which produces the
+effects.</p>
+
+<h3>THE SIAMESE TWINS GALVANISED.</h3>
+
+<p>It will be recollected that the Siamese twins, brought to<span class="pagenum"><a name="Page_204" id="Page_204">204</a></span>
+England in the year 1829, were united by a jointed cartilaginous
+band. A silver tea spoon being placed on the tongue of
+one of the twins and a disc of zinc on the tongue of the other,
+the moment the two metals were brought into contact both
+the boys exclaimed, “Sour, sour;” thus proving that the galvanic
+influence passed from the one to the other through the
+connecting band.</p>
+
+<h3>MINUTE AND VAST BATTERIES.</h3>
+
+<p>Dr. Wollaston made a simple apparatus out of a silver thimble,
+with its top cut off. It was then partially flattened, and
+a small plate of zinc being introduced into it, the apparatus was
+immersed in a weak solution of sulphuric acid. With this minute
+battery, Dr. Wollaston was able to fuse a wire of platinum
+1/3000th of an inch in diameter&mdash;a degree of tenuity to which no
+one had ever succeeded in drawing it.</p>
+
+<p>Upon the same principle (that of introducing a plate of zinc
+between two plates of other metals) Mr. Children constructed
+his immense battery, the zinc plates of which measured six feet
+by two feet eight inches; each plate of zinc being placed between
+two of copper, and each triad of plates being enclosed in
+a separate cell. With this powerful apparatus a wire of platinum,
+1/10th of an inch in diameter and upwards of five feet long,
+was raised to a red heat, visible even in the broad glare of daylight.</p>
+
+<p>The great battery at the Royal Institution, with which Sir
+Humphry Davy discovered the composition of the fixed alkalies,
+was of immense power. It consisted of 200 separate parts, each
+composed of ten double plates, and each plate containing thirty-two
+square inches; the number of double plates being 2000, and
+the whole surface 128,000 square inches.</p>
+
+<p>Mr. Highton, C.E., has made a battery which exposes a surface
+of only 1/100th part of an inch: it consists of but one cell; it
+is less than 1/10000th part of a cubic inch, and yet it produces
+electricity more than enough to overcome all the resistance in
+the inventor’s brother’s patent Gold-leaf Telegraph, and works
+the same powerfully. It is, in short, a battery which, although
+<i>it will go through the eye of a needle</i>, will yet work a telegraph
+well. Mr. Highton had previously constructed a battery in size
+less than 1/40th of a cubic inch: this battery, he found, would
+for a month together ring a telegraph-bell ten miles off.</p>
+
+<h3>ELECTRIC INCANDESCENCE OF CHARCOAL POINTS.</h3>
+
+<p>The most splendid phenomenon of this kind is the combustion
+of charcoal points. Pointed pieces of the residuum obtained
+from gas retorts will answer best, or Bunsen’s composition
+may be used for this purpose. Put two such charcoal<span class="pagenum"><a name="Page_205" id="Page_205">205</a></span>
+points in immediate contact with the wires of your battery;
+bring the points together, and they will begin to burn with a
+dazzling white light. The charcoal points of the large apparatus
+belonging to the Royal Institution became incandescent at
+a distance of 1/30th of an inch; when the distance was gradually
+increased till they were four inches asunder, they continued to
+burn with great intensity, and a permanent stream of light
+played between them. Professor Bunsen obtained a similar
+flame from a battery of four pairs of plates, its carbon surface
+containing 29 feet. The heat of this flame is so intense, that
+stout platinum wire, sapphire, quartz, talc, and lime are reduced
+by it to the liquid form. It is worthy of remark, that no
+combustion, properly so called, takes place in the charcoal itself,
+which sustains only an extremely minute loss in its weight
+and becomes rather denser at the points. The phenomenon is
+attended with a still more vivid brightness if the charcoal points
+are placed in a vacuum, or in any of those gases which are not
+supporters of combustion. Instead of two charcoal points, one
+only need be used if the following arrangement is adopted: lay
+the piece of charcoal on some quicksilver that is connected with
+one pole of the battery, and complete the circuit from the other
+pole by means of a strip of platinum. When Professor Peschel
+used a piece of well-burnt coke in the manner just described,
+he obtained a light which was almost intolerable to the eyes.</p>
+
+<h3>VOLTAIC ELECTRICITY.</h3>
+
+<p>On January 31, 1793, Volta announced to the Royal Society
+his discovery of the development of electricity in metallic bodies.
+Galvani had given the name of Animal Electricity to the power
+which caused spontaneous convulsions in the limbs of frogs
+when the divided nerves were connected by a metallic wire.
+Volta, however, saw the true cause of the phenomena described
+by Galvani. Observing that the effects were far greater when
+the connecting medium consisted of two different kinds of
+metal, he inferred that the principle of excitation existed in
+the metals, and not in the nerves of the animal; and he assumed
+that the exciting fluid was ordinary electricity, produced
+by the contact of the two metals; the convulsions of the frog
+consequently arose from the electricity thus developed passing
+along its nerves and muscles.</p>
+
+<p>In 1800 Volta invented what is now called the Voltaic
+Pile, or compound Galvanic circle.</p>
+
+<blockquote>
+
+<p>The term Animal Electricity (says Dr. Whewell) has been superseded
+by others, of which <i>Galvanism</i> is the most familiar; but I think that
+Volta’s office in this discovery is of a much higher and more philosophical
+kind than that of Galvani; and it would on this account be more fitting
+to employ the term <i>Voltaic Electricity</i>, which, indeed, is very commonly<span class="pagenum"><a name="Page_206" id="Page_206">206</a></span>
+used, especially by our most recent and comprehensive writers.
+The <i>Voltaic pile</i> was a more important step in the history of electricity
+than the Leyden jar had been&mdash;<i>Hist. Ind. Sciences</i>, vol. iii.</p>
+
+<p>No one who wishes to judge impartially of the scientific history of
+these times and of its leaders, will consider Galvani and Volta as equals,
+or deny the vast superiority of the latter over all his opponents or fellow-workers,
+more especially over those of the Bologna school. We shall
+scarcely again find in one man gifts so rich and so calculated for research
+as were combined in Volta. He possessed that “incomprehensible
+talent,” as Dove has called it, for separating the essential from the immaterial
+in complicated phenomena; that boldness of invention which
+must precede experiment, controlled by the most strict and cautious
+mode of manipulation; that unremitting attention which allows no circumstance
+to pass unnoticed; lastly, with so much acuteness, so much
+simplicity, so much grandeur of conception, combined with such depth
+of thought, he had a hand which was the hand of a workman.&mdash;<i>Jameson’s
+Journal</i>, No. 106.</p></blockquote>
+
+<h3>THE VOLTAIC BATTERY AND THE GYMNOTUS.</h3>
+
+<p>“We boast of our Voltaic Batteries,” says Mr. Smee. “I
+should hardly be believed if I were to say that I did not feel
+pride in having constructed my own, especially when I consider
+the extensive operations which it has conducted. But when I
+compare my battery with the battery which nature has given
+to the electrical eel and the torpedo, how insignificant are human
+operations compared with those of the Architect of living
+beings! The stupendous electric eel in the Polytechnic Institution,
+when he seeks to kill his prey, encloses him in a circle;
+then, by volition, causes the voltaic force to be produced, and
+the hapless creature is instantly killed. It would probably require
+ten thousand of my artificial batteries to effect the same
+object, as the creature is killed <i>instanter</i> on receiving the shock.
+As much, however, as my battery is inferior to that of the electric
+fish, so is man superior to the same animal. Man is endowed
+with a power of mind competent to appreciate the force
+of matter, and is thus enabled to make the battery. The eel
+can but use the specific apparatus which nature has bestowed
+upon it.”</p>
+
+<p>Some observations upon the electric current around the
+gymnotus, and notes of experiments with this and other electric
+fish, will be found in <i>Things not generally Known</i>, p. 199.</p>
+
+<h3>VOLTAIC CURRENTS IN MINES.</h3>
+
+<p>Many years ago, Mr. R.&nbsp;W. Fox, from theory entertaining
+a belief that a connection existed between voltaic action in the
+interior of the earth and the arrangement of metalliferous veins,
+and also the progressive increase of temperature in the strata as
+we descend from the surface, endeavoured to verify the same
+from experiment in the mine of Huel Jewel, in Cornwall. His<span class="pagenum"><a name="Page_207" id="Page_207">207</a></span>
+apparatus consisted of small plates of sheet-copper, which were
+fixed in contact with a plate in the veins with copper nails, or
+else wedged closely against them with wooden props stretched
+across the galleries. Between two of these plates, at different
+stations, a communication was made by means of a copper
+wire 1/20th of an inch in diameter, which included a galvanometer
+in its circuit. In some instances 300 fathoms of copper wire
+were employed. It was then found that the intensity of the
+voltaic current was generally greater in proportion to the
+greater abundance of copper ore in the veins, and in some degree
+to the depth of the stations. Hence Mr. Fox’s discovery
+promised to be of practical utility to the miner in discovering
+the relative quantity of ore in the veins, and the directions in
+which it most abounds.</p>
+
+<p>The result of extended experiments, mostly made by Mr.
+Robert Hunt, has not, however, confirmed Mr. Fox’s views.
+It has been found that the voltaic currents detected in the lodes
+are due to the chemical decomposition going on there; and the
+more completely this process of decomposition is established,
+the more powerful are the voltaic currents. Meanwhile these
+have nothing whatever to do with the increase of temperature
+with depth. Recent observations, made in the deep mines of
+Cornwall under the direction of Mr. Fox, do not appear consistent
+with the law of thermic increase as formerly established,
+the shallow mines giving a higher ratio of increase than the
+deeper ones.</p>
+
+<h3>GERMS OF ELECTRIC KNOWLEDGE.</h3>
+
+<p>Two centuries and a half ago, Gilbert recognised that the
+property of attracting light substances when rubbed, be their
+nature what it may, is not peculiar to amber, which is a condensed
+earthy juice cast up by the waves of the sea, and in
+which flying insects, ants, and worms lie entombed as in eternal
+sepulchres. The force of attraction (Gilbert continues) belongs
+to a whole class of very different substances, as glass,
+sulphur, sealing-wax, and all resinous substances&mdash;rock crystal
+and all precious stones, alum and rock-salt. Gilbert measured
+the strength of the excited electricity by means of a small
+needle&mdash;not made of iron&mdash;which moved freely on a pivot, and
+perfectly similar to the apparatus used by Haüy and Brewster
+in testing the electricity excited in minerals by heat and friction.
+“Friction,” says Gilbert further, “is productive of a
+stronger effect in dry than in humid air; and rubbing with
+silk cloths is most advantageous.”</p>
+
+<p>Otto von Guerike, the inventor of the air-pump, was the
+first who observed any thing more than mere phenomena of
+attraction. In his experiments with a rubbed piece of sulphur<span class="pagenum"><a name="Page_208" id="Page_208">208</a></span>
+he recognised the phenomena of repulsion, which subsequently
+led to the establishment of the laws of the sphere of action and
+of the distribution of electricity. <i>He heard the first sound, and
+saw the first light, in artificially-produced electricity.</i> In an experiment
+instituted by Newton in 1675, the first traces of an
+electric charge in a rubbed plate of glass were seen.</p>
+
+<h3>TEMPERATURE AND ELECTRICITY.</h3>
+
+<p>Professor Tyndall has shown that all variations of temperature,
+in metals at least, excite electricity. When the wires of
+a galvanometer are brought in contact with the two ends of a
+heated poker, the prompt deflection of the galvanometer-needle
+indicates that a current of electricity has been sent through
+the instrument. Even the two ends of a spoon, one of which
+has been dipped in hot water, serve to develop an electric
+current; and in cutting a hot beefsteak with a steel knife and
+a silver fork there is an excitement of electricity. The mere
+heat of the finger is sufficient to cause the deflection of the
+galvanometer; and when ice is applied to the part that has
+been previously warmed, the galvanometer-needle is deflected
+in the contrary direction. A small instrument invented by
+Melloni is so extremely sensitive of the action of heat, that
+electricity is excited when the hand is held six inches from it.</p>
+
+<h3>VAST ARRANGEMENT OF ELECTRICITY.</h3>
+
+<p>Professor Faraday has shown that the Electricity which decomposes,
+and that which is evolved in the decomposition of,
+a certain quantity of matter, are alike. What an enormous
+quantity of electricity, therefore, is required for the decomposition
+of a single grain of water! It must be in quantity sufficient
+to sustain a platinum wire 1/104th of an inch in thickness
+red-hot in contact with the air for three minutes and three-quarters.
+It would appear that 800,000 charges of a Leyden
+battery, charged by thirty turns of a very large and powerful
+plate-machine in full action, are necessary to supply electricity
+sufficient to decompose a single grain of water, or to equal the
+quantity of electricity which is naturally associated with the
+elements of that grain of water, endowing them with their mutual
+chemical affinity. Now the above quantity of electricity,
+if passed at once through the head of a rat or a cat, would kill
+it as by a flash of lightning. The quantity is, indeed, equal to
+that which is developed from a charged thunder-cloud.</p>
+
+<h3>DECOMPOSITION OF WATER BY ELECTRICITY.</h3>
+
+<p>Professor Andrews, by an ingenious arrangement, is enabled
+to show that water is decomposed by the common machine;<span class="pagenum"><a name="Page_209" id="Page_209">209</a></span>
+and by using an electrical kite, he was able, in fine weather, to
+produce decomposition, although so slowly that only 1/700000th
+of a grain of water was decomposed per hour. Faraday has
+proved that the decomposition of one single grain of water produces
+more electricity than is contained in the most powerful
+flash of lightning.</p>
+
+<h3>ELECTRICITY IN BREWING.</h3>
+
+<p>Mr. Black, a practical writer upon Brewing, has found that
+by the practice of imbedding the fermentation-vats in the earth,
+and connecting them by means of metallic pipes, an electrical
+current passes through the beer and causes it to turn sour. As
+a preventive, he proposed to place the vats upon wooden blocks,
+or on any other non-conductors, so that they may be insulated.
+It has likewise been ascertained that several brewers who had
+brewed excellent ale on the south side of the street, on removing
+to the north have failed to produce good ale.</p>
+
+<h3>ELECTRIC PAPER.</h3>
+
+<p>Professor Schonbein has prepared paper, as transparent as
+glass and impermeable to water, which develops a very energetic
+electric force. By placing some sheets on each other,
+and simply rubbing them once or twice with the hand, it becomes
+difficult to separate them. If this experiment is performed
+in the dark, a great number of distinct flashes may be
+perceived between the separated surfaces. The disc of the
+electrophorus, placed on a sheet that has been rubbed, produces
+sparks of some inches in length. A thin and very dry
+sheet of paper, placed against the wall, will adhere strongly
+to it for several hours if the hand be passed only once over it.
+If the same sheet be passed between the thumb and fore-finger
+in the dark, a luminous band will be visible. Hence with this
+paper may be made powerful and cheap electrical machines.</p>
+
+<h3>DURATION OF THE ELECTRIC SPARK.</h3>
+
+<p>By means of Professor Wheatstone’s apparatus, the Duration
+of the Electric Spark has been ascertained not to exceed
+the twenty-five-thousandth part of a second. A cannon-ball,
+if illumined in its flight by a flash of lightning, would, in
+consequence of the momentary duration of the light, appear to
+be stationary, and even the wings of an insect, that move ten
+thousand times in a second, would seem at rest.</p>
+
+<h3>VELOCITY OF ELECTRIC LIGHT.</h3>
+
+<p>On comparing the velocities of solar, stellar, and terrestrial
+light, which are all equally refracted in the prism, with the<span class="pagenum"><a name="Page_210" id="Page_210">210</a></span>
+velocity of the light of frictional electricity, we are disposed,
+in accordance with Wheatstone’s ingeniously-conducted experiments,
+to regard the lowest ratio in which the latter excels the
+former as 3:2. According to the lowest results of Wheatstone’s
+apparatus, electric light traverses 288,000 miles in a second.
+If we reckon 189,938 miles for stellar light, according to Struve,
+we obtain the difference of 95,776 miles as the greater velocity
+of electricity in one second.</p>
+
+<p>From the experiment described in Wheatstone’s paper (<i>Philosophical
+Transactions</i> for 1834), it would appear that the human
+eye is capable of perceiving phenomena of light whose
+duration is limited to the millionth part of a second.</p>
+
+<p>In Professor Airy’s experiments with the electric telegraph
+to determine the difference of longitude between Greenwich
+and Brussels, the time spent by the electric current in passing
+from one observatory to the other (270 miles) was found to be
+0·109″ or rather more than <i>the ninth part of a second</i>; and
+this determination rests on 2616 observations: a speed which
+would “girdle the globe” in ten seconds.</p>
+
+<h3>IDENTITY OF ELECTRIC AND MAGNETIC ATTRACTION.</h3>
+
+<p>This vague presentiment of the ancients has been verified
+in our own times. “When electrum (amber),” says Pliny, “is
+animated by friction and heat, it will attract bark and dry
+leaves precisely as the loadstone attracts iron.” The same
+words may be found in the literature of an Asiatic nation, and
+occur in a eulogium on the loadstone by the Chinese physicist
+Knopho, in the fourth century: “The magnet attracts iron
+as amber does the smallest grain of mustard-seed. It is like a
+breath of wind, which mysteriously penetrates through both,
+and communicates itself with the rapidity of an arrow.”</p>
+
+<blockquote>
+
+<p>Humboldt observed with astonishment on the woody banks of the
+Orinoco, in the sports of the natives, that the excitement of electricity
+by friction was known to these savage races. Children may be seen to
+rub the dry, flat, and shining seeds or husks of a trailing plant until
+they are able to attract threads of cotton and pieces of bamboo-cane.
+What a chasm divides the electric pastime of these naked copper-coloured
+Indians from the discovery of a metallic conductor discharging
+its electric shocks, or a pile formed of many chemically-decomposing
+substances, or a light-engendering magnetic apparatus! In such a
+chasm lie buried thousands of years, that compose the history of the intellectual
+development of mankind.&mdash;<i>Humboldt’s Cosmos</i>, vol. i.</p></blockquote>
+
+<h3>THEORY OF THE ELECTRO-MAGNETIC ENGINE.</h3>
+
+<p>Several years ago a speculative American set the industrial
+world of Europe in excitement by this proposition. The Magneto-Electric
+Machines often made use of in the case of rheumatic
+disorders are well known. By imparting a swift rotation<span class="pagenum"><a name="Page_211" id="Page_211">211</a></span>
+to the magnet of such a machine, we obtain powerful currents
+of electricity. If these be conducted through water, the latter
+will be reduced to its two components, oxygen and hydrogen.
+By the combustion of hydrogen water is again generated. If
+this combustion takes place, not in atmospheric air, in which
+oxygen only constitutes a fifth part, but in pure oxygen, and
+if a bit of chalk be placed in the flame, the chalk will be raised
+to a white heat, and give us the sun-like Drummond light: at
+the same time the flame develops a considerable quantity of
+heat. Now the American inventor proposed to utilise in this
+way the gases obtained from electrolytic decomposition; and
+asserted that by the combustion a sufficient amount of heat
+was generated to keep a small steam-engine in action, which
+again drove his magneto-electric machine, decomposed the
+water, and thus continually prepared its own fuel. This would
+certainly have been the most splendid of all discoveries,&mdash;a perpetual
+motion which, besides the force that kept it going,
+generated light like the sun, and warmed all around it. The
+affair, however, failed, as was predicted by those acquainted
+with the physical investigations which bear upon the subject.&mdash;<i>Professor
+Helmholtz.</i></p>
+
+<h3>MAGNETIC CLOCK AND WATCH.</h3>
+
+<p>In the Museum of the Royal Society are two curiosities of
+the seventeenth century which are objects of much interest in
+association with the electric discoveries of our day. These are
+a Clock, described by the Count Malagatti (who accompanied
+Cosmo III., Grand Duke of Tuscany, to inspect the Museum
+in 1669) as more worthy of observation than all the other objects
+in the cabinet. Its “movements are derived from the
+vicinity of a loadstone, and it is so adjusted as to discover the
+distance of countries at sea by the longitude.” The analogy
+between this clock and the electric clock of the present day is
+very remarkable. Of kindred interest is “Hook’s Magnetic
+Watch,” often alluded to in the Royal Society’s Journal-book
+of 1669 as “going slower or faster according to the greater or
+less distance of the loadstone, and so moving regularly in any
+posture.”</p>
+
+<h3>WHEATSTONE’S ELECTRO-MAGNETIC CLOCK.</h3>
+
+<p>In this ingenious invention, the object of Professor Wheatstone
+was to enable a simple clock to indicate exactly the same
+time in as many different places, distant from each other, as
+may be required. A standard clock in an observatory, for example,
+would thus keep in order another clock in each apartment,
+and that too with such accuracy, that <i>all of them, however
+numerous, will beat dead seconds audibly with as great precision<span class="pagenum"><a name="Page_212" id="Page_212">212</a></span>
+as the standard astronomical time-piece with which they are
+connected</i>. But, besides this, the subordinate time-pieces thus
+regulated require none of the mechanism for maintaining or
+regulating the power. They consist simply of a face, with its
+second, minute, and hour hands, and a train of wheels which
+communicate motion from the action of the second-hand to
+that of the hour-hand, in the same manner as an ordinary clock-train.
+Nor is this invention confined to observatories and large
+establishments. The great horologe of St. Paul’s might, by a
+suitable network of wires, or even by the existing metallic
+pipes of the metropolis, be made to command and regulate all
+the other steeple-clocks in the city, and even every clock within
+the precincts of its metallic bounds. As railways and telegraphs
+extend from London nearly to the remotest cities and
+villages, the sensation of time may be transmitted along with
+the elements of language; and the great cerebellum of the
+metropolis may thus constrain by its sympathies, and regulate
+by its power, the whole nervous system of the empire.</p>
+
+<h3>HOW TO MAKE A COMMON CLOCK ELECTRIC.</h3>
+
+<p>M. Kammerer of Belgium effects this by an addition to any
+clock whereby it is brought into contact with the two poles of
+a galvanic battery, the wires from which communicate with a
+drum moved by the clockwork; and every fifteen seconds the
+current is changed, the positive and the negative being transmitted
+alternately. A wire is continued from the drum to the
+electric clock, the movement of which, through the plate-glass
+dial, is seen to be two pairs of small straight electro-magnets,
+each pair having their ends opposite to the other pair, with about
+half an inch space between. Within this space there hangs a
+vertical steel bar, suspended from a spindle at the top. The rod
+has two slight projections on each side parallel to the ends of
+the wire-coiled magnets. When the electric current comes on
+the wire from the positive end of the battery (through the
+drum of the regulator-clock) the positive magnets attract the
+bar to it, the distance being perhaps the sixteenth of an inch.
+When, at the end of fifteen seconds, the negative pole operates,
+repulsion takes effect, and the bar moves to the opposite side.
+This oscillating bar gives motion to a wheel which turns the
+minute and hour hands.</p>
+
+<p>M. Kammerer states, that if the galvanic battery be attached
+to any particular standard clock, any number of clocks,
+wherever placed, in a city or kingdom, and communicating with
+this by a wire, will indicate precisely the same time. Such is
+the precision, that the sounds of three clocks thus beating simultaneously
+have been mistaken as proceeding from one clock.</p>
+
+<p><span class="pagenum"><a name="Page_213" id="Page_213">213</a></span></p>
+
+<h3>DR. FRANKLIN’S ELECTRICAL KITE.</h3>
+
+<p>Several philosophers had observed that lightning and electricity
+possessed many common properties; and the light which
+accompanied the explosion, the crackling noise made by the
+flame, and other phenomena, made them suspect that lightning
+might be electricity in a highly powerful state. But this connection
+was merely the subject of conjecture until, in the year
+1750, Dr. Franklin suggested an experiment to determine the
+question. While he was waiting for the building of a spire at
+Philadelphia, to which he intended to attach his wire, the experiment
+was successfully made at Marly-la-Ville, in France, in
+the year 1752; when lightning was actually drawn from the
+clouds by means of a pointed wire, and it was proved to be
+really the electric fluid.</p>
+
+<blockquote>
+
+<p>Almost every early electrical discovery of importance was made by
+Fellows of the Royal Society, and is to be found recorded in the <i>Philosophical
+Transactions</i>. In the forty-fifth volume occurs the first mention
+of Dr. Franklin’s name, and his theory of positive and negative
+electricity. In 1756 he was elected into the Society, “without any fee
+or other payment.” His previous communications to the <i>Transactions</i>,
+particularly the account of his electrical kite, had excited great interest.
+(<i>Weld’s History of the Royal Society.</i>) It is thus described by him in a
+letter dated Philadelphia, October 1, 1752:</p>
+
+<p>“As frequent mention is made in the public papers from Europe of
+the success of the Marly-la-Ville experiment for drawing the electric fire
+from clouds by means of pointed rods of iron erected on high buildings,
+&amp;c., it may be agreeable to the curious to be informed that the same
+experiment has succeeded in Philadelphia, though made in a different
+and more easy manner, which any one may try, as follows:</p>
+
+<p>Make a small cross of two light strips of cedar, the arms so long as
+to reach to the four corners of a large thin silk handkerchief when extended.
+Tie the comers of the handkerchief to the extremities of the
+cross; so you have the body of a kite, which, being properly accommodated
+with a tail, loop, and string, will rise in the air like a kite made
+of paper; but this, being of silk, is fitter to bear the wet and wind of a
+thunder-gust without tearing. To the top of the upright stick of the
+cross is to be fixed a very sharp-pointed wire, rising a foot or more
+above the wood. To the end of the twine, next the band, is to be tied
+a silk ribbon; and where the twine and silk join a key may be fastened.</p>
+
+<p>The kite is to be raised when a thunder-gust appears to be coming
+on, and the person who holds the string must stand within a door or
+window, or under some cover, so that the silk ribbon may not be wet;
+and care must be taken that the twine does not touch the frame of the
+door or window. As soon as any of the thunder-clouds come over the
+kite, the pointed wire will draw the electric fire from them; and the
+kite, with all the twine, will be electrified; and the loose filaments of
+the twine will stand out every way, and be attracted by an approaching
+finger.</p>
+
+<p>When the rain has wet the kite and twine, so that it can conduct
+the electric fire freely, you will find it stream out plentifully from the
+key on the approach of your knuckle. At this key the phial may be
+charged; and from electric fire thus obtained spirits may be kindled,<span class="pagenum"><a name="Page_214" id="Page_214">214</a></span>
+and all the other electrical experiments be performed which are usually
+done by the help of a rubbed-glass globe or tube; and thus the sameness
+of the electric matter with that of lightning is completely demonstrated.”&mdash;<i>Philosophical
+Transactions.</i></p></blockquote>
+
+<p>Of all this great man’s (Franklin’s) scientific excellencies,
+the most remarkable is the smallness, the simplicity, the apparent
+inadequacy of the means which he employed in his
+experimental researches. His discoveries were all made with
+hardly any apparatus at all; and if at any time he had been
+led to employ instruments of a somewhat less ordinary description,
+he never rested satisfied until he had, as it were, afterwards
+translated the process by resolving the problem with
+such simple machinery that you might say he had done it
+wholly unaided by apparatus. The experiments by which the
+identity of lightning and electricity was demonstrated were
+made with a sheet of brown paper, a bit of twine or silk thread,
+and an iron key!&mdash;<i>Lord Brougham.</i><a name="FNanchor_50" id="FNanchor_50" href="#Footnote_50" class="fnanchor">50</a></p>
+
+<h3>FATAL EXPERIMENT WITH LIGHTNING.</h3>
+
+<p>These experiments are not without danger; and a flash of
+lightning has been found to be a very unmanageable instrument.
+In 1753, M. Richman, at St. Petersburg, was making an experiment
+of this kind by drawing lightning into his room, when,
+incautiously bringing his head too near the wire, he was struck
+dead by the flash, which issued from it like a globe of blue fire,
+accompanied by a dreadful explosion.</p>
+
+<h3>FARADAY’S ELECTRICAL ILLUSTRATIONS.</h3>
+
+<p>The following are selected from the very able series of lectures
+delivered by Professor Faraday at the Royal Institution:</p>
+
+<blockquote>
+
+<p><i>The Two Electricities.</i>&mdash;After having shown by various experiments
+the attractions and repulsions of light substances from excited glass and
+from an excited tube of gutta-percha, Professor Faraday proceeds to
+point out the difference in the character of the electricity produced by
+the friction of the two substances. The opposite characters of the electricity
+evolved by the friction of glass and of that excited by the friction
+of gutta-percha and shellac are exhibited by several experiments, in
+which the attraction of the positive and negative electricities to each
+other and the neutralisation of electrical action on the combination of
+the two forces are distinctly observable. Though adopting the terms
+“positive” and “negative” in distinguishing the electricity excited by
+glass from that excited by gutta-percha and resinous bodies, Professor
+Faraday is strongly opposed to the Franklinian theory from which these
+terms are derived. According to Franklin’s view of the nature of electrical
+excitement, it arises from the disturbance, by friction or other
+means, of the natural quantity of one electric fluid which is possessed
+by all bodies; an excited piece of glass having more than its natural<span class="pagenum"><a name="Page_215" id="Page_215">215</a></span>
+share, which has been taken from the rubber, the latter being consequently
+in a minus or negative state. This theory Professor Faraday
+considers to be opposed to the distinct characteristic actions of the two
+forces; and, in his opinion, it is impossible to deprive any body of electricity,
+and reduce it to the minus state of Franklin’s hypothesis.
+Taking a Zamboni’s pile, he applies its two ends separately to an electrometer,
+to show that each end produces opposite kinds of electricity,
+and that the zero, or absence of electrical excitement, only exists in the
+centre of the pile. To prove how completely the two electricities neutralise
+each other, an excited rod of gutta-percha and the piece of flannel
+with which it has been rubbed are laid on the top of the electrometer
+without any sign of electricity whilst they are together; but when either
+is removed, the gold leaves diverge with positive and negative electricity
+alternately. The Professor dwells strongly on the peculiarity of the
+dual force of electricity, which, in respect of its duality, is unlike any
+other force in nature. He then contrasts its phenomena of instantaneous
+conduction with those of the somewhat analogous force of heat;
+and he illustrates by several striking experiments the peculiar property
+which static electricity possesses of being spread only over the surfaces
+of bodies. A metal ice-pail is placed on an insulated stand and electrified,
+and a metal ball suspended by a string is introduced, and touches
+the bottom and sides without having any electricity imparted to it, but
+on touching the outside it becomes strongly electrical. The experiment
+is repeated with a wooden tub with the same result; and Professor Faraday
+mentions the still more remarkable manner in which he has
+proved the surface distribution of electricity by having a small chamber
+constructed and covered with tinfoil, which can be insulated; and whilst
+torrents of electricity are being evolved from the external surface, he
+enters it with a galvanometer, and cannot perceive the slightest manifestation
+of electricity within.</p>
+
+<p><i>The Two Threads.</i>&mdash;A curious experiment is made with two kinds of
+thread used as the conducting force. From the electric machine on the
+table a silk thread is first carried to the indicator a yard or two off, and
+is shown to be a non-conductor when the glass tube is rubbed and applied
+to the machine (although the silk, when wetted, conducted); while
+a metallic thread of the same thickness, when treated in the same way,
+conducts the force so much as to vehemently agitate the gold leaves
+within the indicator.</p>
+
+<p><i>Non-conducting Bodies.</i>&mdash;The action that occurs in bodies which
+cannot conduct is the most important part of electrical science. The
+principle is illustrated by the attraction and repulsion of an electrified
+ball of gilt paper by a glass tube, between which and the ball a sheet
+of shellac is suspended. The nearer a ball of another description&mdash;an
+unelectrical insulated body&mdash;is brought to the Leyden jar when charged,
+the greater influence it is seen to possess over the gold leaf within the
+indicator, by induction, not by conduction. The questions, how electricities
+attract each other, what kind of electricity is drawn from the
+machine to the hand, how the hand was electric, are thus illustrated.
+To show the divers operations of this wonderful force, a tub (a bad conductor)
+is placed by the electric machine. When the latter is charged,
+a ball, having been electrified from it, is held in the tub, and rattles
+against its sides and bottom. On the application of the ball to the indicator,
+the gold leaf is shown not to move, whereas it is agitated manifestly
+when the same process is gone through with the exception that
+the ball is made to touch the outside only of the tub. Similar experiments<span class="pagenum"><a name="Page_216" id="Page_216">216</a></span>
+with a ball in an ice-pail and a vessel of wire-gauze, into the
+latter of which is introduced a mouse, which is shown to receive no
+shock, and not to be frightened at all; while from the outside of the
+vessel electric sparks are rapidly produced. This latter demonstration
+proves that, as the mouse, so men and women, might be safe inside a
+building with proper conductors while lightning played about the exterior.
+The wire-gauze being turned inside out, the principle is shown
+to be irreversible in spite of the change&mdash;what has been the unelectrical
+inside of the vessel being now, when made the outside portion, capable
+of receiving and transmitting the power, while the original outside is
+now unelectrical.</p>
+
+<p><i>Repulsion of Bodies.</i>&mdash;A remarkable and playful experiment, by
+which the repulsion of bodies similarly electrified is illustrated, consists
+in placing a basket containing a heap of small pieces of paper on an insulated
+stand, and connecting it with the prime conductor of the electrical
+machine; when the pieces of paper rise rapidly after each other into
+the air, and descend on the lecture-table like a fall of snow. The effect
+is greatly increased when a metal disc is substituted for the basket.</p></blockquote>
+
+<h3>ORIGIN OF THE LEYDEN JAR.</h3>
+
+<p>Muschenbroek and Linnæus had made various experiments
+of a strong kind with water and wire. The former, as appears
+from a letter of his to Réaumur, filled a small bottle with water,
+and having corked it up, passed a wire through the cork into
+the bottle. Having rubbed the vessel on the outside and suspended
+it to the electric machine, he was surprised to find that
+on trying to pull the wire out he was subjected to an awfully
+severe shock in his joints and his whole body, such as he declared
+he would not suffer again for any experiment. Hence
+the Leyden jar, which owes its name to the University of Leyden,
+with which, we believe, Muschenbroek was connected.&mdash;<i>Faraday.</i></p>
+
+<h3>DANGER TO GUNPOWDER MAGAZINES.</h3>
+
+<p>By the illustration of a gas globule, which is ignited from a
+spark by induction, Mr. Faraday has proved in a most interesting
+manner that the corrugated-iron roofs of some gunpowder-magazines,&mdash;on
+the subject of which he had often been consulted
+by the builders, with a view to the greater safety of these manufactories,&mdash;are
+absolutely dangerous by the laws of induction;
+as, by the return of induction, while a storm was discharging
+itself a mile or two off, a secondary spark might ignite the building.</p>
+
+<h3>ARTIFICIAL CRYSTALS AND MINERALS.&mdash;“THE CROSSE MITE.”</h3>
+
+<p>Among the experimenters on Electricity in our time who
+have largely contributed to the “Curiosities of Science,” Andrew
+Crosse is entitled to special notice. In his school-days he
+became greatly attached to the study of electricity; and on settling<span class="pagenum"><a name="Page_217" id="Page_217">217</a></span>
+on his paternal estate, Fyne Court, on the Quantock Hills
+in Somersetshire, he there devoted himself to chemistry, mineralogy,
+and electricity, pursuing his experiments wholly independently
+of theories, and searching only for facts. In Holwell
+Cavern, near his residence, he observed the sides and the roof
+covered with Arragonite crystallisations, when his observations
+led him to conclude that the crystallisations were the effects,
+at least to some extent, of electricity. This induced him to
+make the attempt to form artificial crystals by the same means,
+which he began in 1807. He took some water from the cave,
+filled a tumbler, and exposed it to the action of a voltaic battery
+excited by water alone, letting the platinum-wires of the
+battery fall on opposite sides of the tumbler from the opposite
+poles of the battery. After ten days’ constant action, he produced
+crystals of carbonate of lime; and on repeating the experiment
+in the dark, he produced them in six days. Thus Mr.
+Crosse simulated in his laboratory one of the hitherto most mysterious
+processes of nature.</p>
+
+<p>He pursued this line of research for nearly thirty years at
+Fyne Court, where his electrical-room and laboratory were on
+an enormous scale: the apparatus had cost some thousands of
+pounds, and the house was nearly full of furnaces. He carried
+an insulated wire above the tops of the trees around his house
+to the length of a mile and a quarter, afterwards shortened to
+1800 feet. By this wire, which was brought into connection
+with the apparatus in a chamber, he was enabled to see continually
+the changes in the state of the atmosphere, and could
+use the fluid so collected for a variety of purposes. In 1816,
+at a meeting of country gentlemen, he prophesied that, “by
+means of electrical agency, we shall be able to communicate our
+thoughts simultaneously with the uttermost ends of the earth.”
+Still, though he foresaw the powers of the medium, he did not
+make any experiments in that direction, but confined himself
+to the endeavour to produce crystals of various kinds. He ultimately
+obtained forty-one mineral crystals, or minerals uncrystallised,
+in the form in which they are produced by nature, including
+one sub-sulphate of copper&mdash;an entirely new mineral,
+neither found in nature nor formed by art previously. His belief
+was that even diamonds might be produced in this way.</p>
+
+<p>Mr. Crosse worked alone in his retreat until 1836, when,
+attending the meeting of the British Association at Bristol,
+he was induced to explain his experiments, for which he was
+highly complimented by Dr. Buckland, Dr. Dalton, Professor
+Sedgwick, and others.<a name="FNanchor_51" id="FNanchor_51" href="#Footnote_51" class="fnanchor">51</a></p>
+
+<p><span class="pagenum"><a name="Page_218" id="Page_218">218</a></span>
+Shortly after Mr. Crosse’s return to Fyne Court, while pursuing
+his experiments for forming crystals from a highly caustic
+solution out of contact with atmospheric air, he was greatly
+surprised by the appearance of an insect. Black flint, burnt to
+redness and reduced to powder, was mixed with carbonate of
+potash, and exposed to a strong heat for fifteen minutes; and the
+mixture was poured into a black-lead crucible in an air furnace.
+It was reduced to powder while warm, mixed with boiling
+water, kept boiling for some minutes, and then hydrochloric
+acid was added to supersaturation. After being exposed to voltaic
+action for twenty-six days, a perfect insect of the Acari
+tribe made its appearance, and in the course of a few weeks
+about a hundred more. The experiment was repeated in other
+chemical fluids with the like results; and Mr. Weeks of Sandwich
+afterwards produced the Acari inferrocyanerret of potassium.
+The Acarus of Mr. Crosse was found to contribute a new
+species of that genus, nearly approaching the Acari found in
+cheese and flour, or more nearly, Hermann’s <i>Acarus dimidiatus</i>.</p>
+
+<p>This discovery occasioned great excitement. The possibility
+was denied, though Mr. Faraday is said to have stated in the
+same year that he had seen similar appearances in his own electrical
+experiments. Mr. Crosse was now accused of impiety and
+aiming at creation, to which attacks he thus replied:</p>
+
+<blockquote>
+
+<p>As to the appearance of the acari under long-continued electrical
+action, I have never in thought, word, or deed given any one a right
+to suppose that I considered them as a creation, or even as a formation,
+from inorganic matter. To create is to form a something out of a nothing.
+To annihilate is to reduce that something to a nothing. Both of
+these, of course, can only be the attributes of the Almighty. In fact, I
+can assure you most sacredly that I have never dreamed of any theory
+sufficient to account for their appearance. I confess that I was not a
+little surprised, and am so still, and quite as much as I was when the
+acari made their first appearance. Again, I have never claimed any
+merit as attached to these experiments. It was a matter of chance; I
+was looking for silicious formations, and animal matter appeared instead.</p></blockquote>
+
+<p>These Acari, if removed from their birthplace, lived and propagated;
+but uniformly died on the first recurrence of frost, and
+were entirely destroyed if they fell back into the fluid whence
+they arose.</p>
+
+<p>One of Mr. Crosse’s visitors thus describes the vast electrical
+room at Fyne Court:</p>
+
+<blockquote>
+
+<p>Here was an immense number of jars and gallipots, containing fluids
+on which electricity was operating for the production of crystals. But
+you are startled in the midst of your observations by the smart crackling
+sound that attends the passage of the electrical spark; you hear also<span class="pagenum"><a name="Page_219" id="Page_219">219</a></span>
+the rumbling of distant thunder. The rain is already plashing in great
+drops against the glass, and the sound of the passing sparks continues
+to startle your ear; you see at the window a huge brass conductor, with
+a discharging rod near it passing into the floor, and from the one knob to
+the other sparks are leaping with increasing rapidity and noise, every
+one of which would kill twenty men at one blow, if they were linked together
+hand in hand and the spark sent through the circle. From this
+conductor wires pass off without the window, and the electric fluid is
+conducted harmlessly away. Mr. Crosse approached the instrument as
+boldly as if the flowing stream of fire were a harmless spark. Armed
+with his insulated rod, he sent it into his batteries: having charged
+them, he showed how wire was melted, dissipated in a moment, by its
+passage; how metals&mdash;silver, gold, and tin&mdash;were inflamed and burnt
+like paper, only with most brilliant hues. He showed you a mimic aurora
+and a falling-star, and so proved to you the cause of those beautiful
+phenomena.</p></blockquote>
+
+<p>Mr. Crosse appears to have produced in all “about 200 varieties
+of minerals, exactly resembling in all respects similar ones
+found in nature.” He tried also a new plan of extracting gold
+from its ores by an electrical process, which succeeded, but was
+too expensive for common use. He was in the habit of saying
+that he could, like Archimedes, move the world “if he were
+able to construct a battery at once cheap, powerful, and durable.”
+His process of extracting metals from their ores has been
+patented. Among his other useful applications of electricity
+are the purifying by its means of brackish or sea-water, and the
+improving bad wine and brandy. He agreed with Mr. Quekett
+in thinking that it is by electrical action that silica and other
+mineral substances are carried into and assimilated by plants.
+Negative electricity Mr. Crosse found favourable to no plants
+except fungi; and positive electricity he ascertained to be injurious
+to fungi, but favourable to every thing else.</p>
+
+<p>Mr. Crosse died in 1855. His widow has published a very
+interesting volume of <i>Memorials</i> of the ingenious experimenter,
+from which we select the following:</p>
+
+<blockquote>
+
+<p>On one occasion Mr. Crosse kept a pair of soles under the electric
+action for three months; and at the end of that time they were sent to
+a friend, whose domestics knew nothing of the experiment. Before the
+cook dressed them, her master asked her whether she thought they were
+fresh, as he had some doubts. She replied that she was sure they were
+fresh; indeed, she said she could swear that they were alive yesterday!
+When served at table they appeared like ordinary fish; but when the
+family attempted to eat them, they were found to be perfectly tasteless&mdash;the
+electric action had taken away all the essential oil, leaving the
+fish unfit for food. However, the process is exceedingly useful for keeping
+fish, meat, &amp;c. fresh and <i>good</i> for ten days or a fortnight. I have
+never heard a satisfactory explanation of the cause of the antiseptic
+power communicated to water by the passage of the electric current.
+Whether ozone has not something to do with it, may be a question.
+The same effect is produced whichever two dissimilar metals are used.</p></blockquote>
+
+<hr />
+
+<p><span class="pagenum"><a name="Page_220" id="Page_220">220</a></span></p>
+
+<div class="chapter"></div>
+<h2><a name="Electric" id="Electric"></a>The Electric Telegraph.</h2>
+
+<h3>ANTICIPATIONS OF THE ELECTRIC TELEGRAPH.</h3>
+
+<p>The great secret of ubiquity, or at least of instantaneous transmission,
+has ever exercised the ingenuity of mankind in various
+romantic myths; and the discovery of certain properties of the
+loadstone gave a new direction to these fancies.</p>
+
+<p>The earliest anticipation of the Electric Telegraph of this
+purely fabulous character forms the subject of one of the <i>Prolusiones
+Academicæ</i> of the learned Italian Jesuit Strada, first
+published at Rome in the year 1617. Of this poem a free
+translation appeared in 1750. Strada’s fancy was this: “There
+is,” he supposes, “a species of loadstone which possesses such
+virtue, that if two needles be touched with it, and then balanced
+on separate pivots, and the one be turned in a particular
+direction, the other will sympathetically move parallel
+to it. He then directs each of these needles to be poised and
+mounted parallel on a dial having the letters of the alphabet
+arranged round it. Accordingly, if one person has one of the
+dials, and another the other, by a little pre-arrangement as to
+details a correspondence can be maintained between them at
+any distance by simply pointing the needles to the letters of
+the required words. Strada, in his poetical reverie, dreamt that
+some such sympathy might one day be found to hold up the
+Magnesian Stone.”</p>
+
+<p>Strada’s conceit seems to have made a profound impression
+on the master-minds of the day. His poem is quoted in many
+works of the seventeenth and eighteenth centuries; and Bishop
+Wilkins, in his book on Cryptology, is strangely afraid lest
+his readers should mistake Strada’s fancy for fact. Wilkins
+writes: “This invention is altogether imaginary, having no
+foundation in any real experiment. You may see it frequently
+confuted in those that treat concerning magnetical virtues.”</p>
+
+<p>Again, Addison, in the 241st No. of the <i>Spectator</i>, 1712,
+describes Strada’s “Chimerical correspondence,” and adds that,
+“if ever this invention should be revived or put in practice,”
+he “would propose that upon the lover’s dial-plate there
+should be written not only the four-and-twenty letters, but several
+entire words which have always a place in passionate epistles,
+as flames, darts, die, language, absence, Cupid, heart, eyes,
+being, drown, and the like. This would very much abridge the
+lover’s pains in this way of writing a letter, as it would enable<span class="pagenum"><a name="Page_221" id="Page_221">221</a></span>
+him to express the most useful and significant words with a
+single touch of the needle.”</p>
+
+<p>After Strada and his commentators comes Henry Van Etten,
+who shows how “Claude, being at Paris, and John at Rome,
+might converse together, if each had a needle touched by a
+stone of such virtue that as one moved itself at Paris the other
+should be moved at Rome:” he adds, “it is a fine invention,
+but I do not think there is a magnet in the world which has
+such virtue; besides, it is inexpedient, for treasons would be
+too frequent and too much protected. (<i>Recréations Mathématiques</i>:
+see 5th edition, Paris, 1660, p. 158.) Sir Thomas Browne
+refers to this “conceit” as “excellent, and, if the effect would
+follow, somewhat divine;” but he tried the two needles touched
+with the same loadstone, and placed in two circles of letters,
+“one friend keeping one and another the other, and agreeing
+upon an hour when they will communicate,” and found the tradition
+a failure that, “at what distance of place soever, when
+one needle shall be removed unto any letter, the other, by a
+wonderful sympathy, will move unto the same.” (See <i>Vulgar
+Errors</i>, book ii. ch. iii.)</p>
+
+<p>Glanvill’s <i>Vanity of Dogmatizing</i>, a work published in 1661,
+however, contains the most remarkable allusion to the prevailing
+telegraphic fancy. Glanvill was an enthusiast, and he clearly
+predicts the discovery and general adoption of the electric telegraph.
+“To confer,” he says, “at the distance of the Indies
+by sympathetic conveyance may be as usual to future times as
+to us in a literary correspondence.” By the word “sympathetic”
+he evidently intended to convey magnetic agency; for he
+subsequently treats of “conference at a distance by impregnated
+needles,” and describes the device substantially as it is
+given by Sir Thomas Browne, adding, that though it did not
+then answer, “by some other such way of magnetic efficiency
+it may hereafter with success be attempted, when magical history
+shall be enlarged by riper inspection; and ’tis not unlikely
+but that present discoveries might be improved to the performance.”
+This may be said to close the most speculative or mythical
+period in reference to the subject of electro-telegraphy.</p>
+
+<p>Electricians now began to be sedulous in their experiments
+upon the new force by friction, then the only known method
+of generating electricity. In 1729, Stephen Gray, a pensioner
+of the Charter-house, contrived a method of making electrical
+signals through a wire 765 feet long; yet this most important
+experiment did not excite much attention. Next Dr. Watson,
+of the Royal Society, experimented on the possibility of transmitting
+electricity through a large circuit from the simple fact of
+Le Monnier’s account of his feeling the stroke of the electrified
+fires through two of the basins of the Tuileries (which occupy<span class="pagenum"><a name="Page_222" id="Page_222">222</a></span>
+nearly an acre), by means of an iron chain lying upon the ground
+and stretched round half their circumference. In 1745, Dr. Watson,
+assisted by several members of the Royal Society, made a
+series of experiments to ascertain how far electricity could be
+conveyed by means of conductors. “They caused the shock to
+pass across the Thames at Westminster Bridge, the circuit being
+completed by making use of the river for one part of the chain
+of communication. One end of the wire communicated with
+the coating of a charged phial, the other being held by the observer,
+who in his other hand held an iron rod which he dipped
+into the river. On the opposite side of the river stood a gentleman,
+who likewise dipped an iron rod in the river with one
+hand, and in the other held a wire the extremity of which
+might be brought into contact with the wire of the phial. Upon
+making the discharge, the shock was felt simultaneously by
+both the observers.” (<i>Priestley’s History of Electricity.</i>) Subsequently
+the same parties made experiments near Shooter’s
+Hill, when the wires formed a circuit of four miles, and conveyed
+the shock with equal facility,&mdash;“a distance which without
+trial,” they observed, “was too great to be credited.”<a name="FNanchor_52" id="FNanchor_52" href="#Footnote_52" class="fnanchor">52</a> These
+experiments in 1747 established two great principles: 1, that
+the electric current is transmissible along nearly two miles and
+a half of iron wire; 2, that the electric current may be completed
+by burying the poles in the earth at the above distance.</p>
+
+<p>In the following year, 1748, Benjamin Franklin performed
+his celebrated experiments on the banks of the Schuylkill, near
+Philadelphia; which being interrupted by the hot weather, they
+were concluded by a picnic, when spirits were fired by an electric
+spark sent through a wire in the river, and a turkey was
+killed by the electric shock, and roasted by the electric jack
+before a fire kindled by the electrified bottle.</p>
+
+<p>In the year 1753, there appeared in the <i>Scots’ Magazine</i>, vol.
+xv., definite proposals for the construction of an electric telegraph,
+requiring as many conducting wires as there are letters
+in the alphabet; it was also proposed to converse by chimes,
+by substituting bells for the balls. A similar system of telegraphing
+was next invented by Joseph Bozolus, a Jesuit, at
+Rome; and next by the great Italian electrician Tiberius Cavallo,
+in his treatise on Electricity.</p>
+
+<p>In 1787, Arthur Young, when travelling in France, saw a
+model working telegraph by M. Lomond: “You write two or
+three words on a paper,” says Young; “he takes it with him
+into a room, and turns a machine enclosed in a cylindrical case,<span class="pagenum"><a name="Page_223" id="Page_223">223</a></span>
+at the top of which is an electrometer&mdash;a small fine pith-ball;
+a wire connects with a similar cylinder and electrometer in a
+distant apartment; and his wife, by remarking the corresponding
+motions of the ball, writes down the words they indicate:
+from which it appears that he has formed an alphabet of motions.
+As the length of the wire makes no difference in the
+effect, a correspondence might be carried on at any distance.
+Whatever the use may be, the invention is beautiful.”</p>
+
+<p>We now reach a new epoch in the scientific period&mdash;the discovery
+of the Voltaic Pile. In 1794, according to <i>Voigt’s Magazine</i>,
+Reizen made use of the electric spark for the telegraph;
+and in 1798 Dr. Salva of Madrid constructed a similar telegraph,
+which the Prince of Peace subsequently exhibited to the
+King of Spain with great success.</p>
+
+<p>In 1809, Soemmering exhibited a telegraphic apparatus
+worked by galvanism before the Academy of Sciences at Munich,
+in which the mode of signalling consisted in the development
+of gas-bubbles from the decomposition of water placed in a
+series of glass tubes, each of which denoted a letter of the alphabet.
+In 1813, Mr. Sharpe, of Doe Hill near Alfreton, devised
+a <i>voltaic</i>-electric telegraph, which he exhibited to the
+Lords of the Admiralty, who spoke approvingly of it, but declined
+to carry it into effect. In the following year, Soemmering
+exhibited a <i>voltaic</i>-electric telegraph of his own construction,
+which, however, was open to the objection of there being as
+many wires as signs or letters of the alphabet.</p>
+
+<p>The next invention is of much greater importance. Upon
+the suggestion of Cavallo, already referred to, Francis Ronalds
+constructed a perfect electric telegraph, employing frictional
+electricity notwithstanding Volta’s discoveries had been known
+in England for sixteen years. This telegraph was exhibited at
+Hammersmith in 1816:<a name="FNanchor_53" id="FNanchor_53" href="#Footnote_53" class="fnanchor">53</a> it consisted of a single insulated wire,
+the indication being by pith-balls in front of a dial. When the
+wire was charged, the balls were divergent, but collapsed when
+the wire was discharged; at the same time were employed two
+clocks, with lettered discs for the signals. “If, as Paley asserts
+(and Coleridge denies), ‘he alone discovers who proves,’ Ronalds
+is entitled to the appellation of the first discoverer of an
+efficient electric telegraph.” (<i>Saturday Review</i>, No. 147<a name="FNanchor_54" id="FNanchor_54" href="#Footnote_54" class="fnanchor">54</a>) Nevertheless
+the Government of the day refused to avail itself of this
+admirable contrivance.</p>
+
+<p>In 1819, Oersted made his great discovery of the deflection,
+by a current of electricity, of a magnetic needle at right angles<span class="pagenum"><a name="Page_224" id="Page_224">224</a></span>
+to such current. Dr. Hamel of St. Petersburg states that
+Baron Schilling was the first to apply Oersted’s discovery to
+telegraphy; Ampère had previously suggested it, but his plan
+was very complicated, and Dr. Hamel maintains that Schilling
+first realised the idea by actually producing an electro-magnetic
+telegraph simpler in construction than that which
+Ampère had <i>imagined</i>. In 1836, Professor Muncke of Heidelberg,
+who had inspected Schilling’s telegraphic apparatus, explained
+the same to William Fothergill Cooke, who in the
+following year returned to England, and subsequently, with
+Professor Wheatstone, laboured simultaneously for the introduction
+of the electro-magnetic telegraph upon the English
+railways; the first patent for which was taken out in the joint
+names of these two gentlemen.</p>
+
+<p>In 1844, Professor Wheatstone, with one of his telegraphs,
+formed a communication between King’s College and the lofty
+shot-tower on the opposite bank of the Thames: the wire was
+laid along the parapets of the terrace of Somerset House and
+Waterloo Bridge, and thence to the top of the tower, about 150
+feet high, where a telegraph was placed; the wire then descended,
+and a plate of zinc attached to its extremity was
+plunged into the mud of the river, whilst a similar plate attached
+to the extremity at the north side was immersed in the
+water. The circuit was thus completed by the entire breadth
+of the Thames, and the telegraph acted as well as if the circuit
+were entirely metallic.</p>
+
+<p>Shortly after this experiment, Professor Wheatstone and
+Mr. Cooke laid down the first working electric telegraph on the
+Great Western Railway, from Paddington to Slough.</p>
+
+<h3>ELECTRIC GIRDLE FOR THE EARTH.</h3>
+
+<p>One of our most profound electricians is reported to have
+exclaimed: “Give me but an unlimited length of wire, with a
+small battery, and I will girdle the universe with a sentence in
+forty minutes.” Yet this is no vain boast; for so rapid is the
+transition of the electric current along the line of the telegraph
+wire, that, supposing it were possible to carry the wires eight
+times round the earth, the transit would occupy but <i>one second
+of time</i>!</p>
+
+<h3>CONSUMPTION OF THE ELECTRIC TELEGRAPH.</h3>
+
+<p>It is singular to see how this telegraphic agency is measured
+by the chemical consumption of zinc and acid. Mr. Jones
+(who has written a work upon the Electric Telegraphs of America)
+estimates that to work 12,000 miles of telegraph about
+3000 zinc cups are used to hold the acid: these weigh about
+9000 lbs., and they undergo decomposition by the galvanic<span class="pagenum"><a name="Page_225" id="Page_225">225</a></span>
+action in about six months, so that 18,000 lbs. of zinc are consumed
+in a year. There are also about 3600 porcelain cups to
+contain nitric acid; it requires 450 lbs. of acid to charge them
+once, and the charge is renewed every fortnight, making about
+12,000 lbs. of nitric acid in a year.</p>
+
+<h3>TIME LOST IN ELECTRIC MESSAGES.</h3>
+
+<p>Although it may require an hour, or two or three hours, to
+transmit a telegraphic message to a distant city, yet it is the
+mechanical adjustment by the sender and receiver which really
+absorbs this time; the actual transit is practically instantaneous,
+and so it would be from here to the antipodes, so far as
+the current itself is concerned.</p>
+
+<h3>THE ELECTRIC TELEGRAPH IN ASTRONOMY AND THE
+DETERMINATION OF LONGITUDE.</h3>
+
+<p>The Electric Telegraph has become an instrument in the
+hands of the astronomer for determining the difference of longitude
+between two observatories. Thus in 1854 the difference
+of longitude between London and Paris was determined within
+a limit of error which amounted barely to a quarter of a second.
+The sudden disturbances of the magnetic needle, when freely
+suspended, which seem to take place simultaneously over whole
+continents, if not over the whole globe, from some unexplained
+cause, are pointed out as means by which the differences of longitude
+between the magnetic observatories may possibly be determined
+with greater precision than by any yet known method.</p>
+
+<p>So long ago as 1839 Professor Morse suggested some experiments
+for the determination of Longitudes; and in June
+1844 the difference of longitude between Washington and Baltimore
+was determined by electric means under his direction.
+Two persons were stationed at these two towns, with clocks
+carefully adjusted to the respective spots; and a telegraphic
+signal gave the means of comparing the two clocks at a given
+instant. In 1847 the relative longitudes of New York, Philadelphia,
+and Washington were determined by means of the
+electric telegraph by Messrs. Keith, Walker, and Loomis.</p>
+
+<h3>NON-INTERFERENCE OF GALVANIC WAVES ON THE SAME WIRE.</h3>
+
+<p>One of the most remarkable facts in the economy of the
+telegraph is, that the line, when connected with a battery in
+action, propagates the hydro-galvanic waves in either direction
+without interference. As several successive syllables of sound
+may set out in succession from the same place, and be on their
+way at the same time, to a listener at a distance, so also, where
+the telegraph-line is long enough, several waves may be on
+their way from the signal station before the first one reaches<span class="pagenum"><a name="Page_226" id="Page_226">226</a></span>
+the receiving station; two persons at a distance may pronounce
+several syllables at the same time, and each hear those
+emitted by the other. So, on a telegraph-line of two or three
+thousand miles in length in the air, and the same in the
+ground, two operators may at the same instant commence a
+series of several dots and lines, and each receive the other’s
+writings, though the waves have crossed each other on the way.</p>
+
+<h3>EFFECT OF LIGHTNING UPON THE ELECTRIC TELEGRAPH.</h3>
+
+<p>In the storm of Sunday April 2, 1848, the lightning had a
+very considerable effect on the wires of the electric telegraph,
+particularly on the line of railway eastward from Manchester
+to Normanton. Not only were the needles greatly deflected,
+and their power of answering to the handles considerably weakened,
+but those at the Normanton station were found to have
+had their poles reversed by some action of the electric fluid in
+the atmosphere. The damage, however, was soon repaired, and
+the needles again put in good working order.</p>
+
+<h3>ELECTRO-TELEGRAPHIC MESSAGE TO THE STARS.</h3>
+
+<p>The electric fluid travels at the mean rate of 20,000 miles
+in a second under ordinary circumstances; therefore, if it were
+possible to establish a telegraphic communication with the star
+61 Cygni, it would require ninety years to send a message there.</p>
+
+<p>Professor Henderson and Mr. Maclear have fully confirmed
+the annual parallax of α Centauri to amount to a second of arc,
+which gives about twenty billions of miles as its distance from
+our system; a ray of light would arrive from α Centauri to us in
+little more than three years, and a telegraphic despatch would
+arrive there in thirty years.</p>
+
+<h3>THE ATLANTIC TELEGRAPH.</h3>
+
+<p>The telegraphic communication between England and the
+United States is so grand a conception, that it would be impossible
+to detail its scientific and mechanical relations within the
+limits of the present work. All that we shall attempt, therefore,
+will be to glance at a few of the leading operations.</p>
+
+<p>In the experiments made before the Atlantic Telegraph was
+finally decided on, 2000 miles of subterranean and submarine
+telegraphic wires, ramifying through England and Ireland and
+under the waters of the Irish Sea, were specially connected for
+the purpose; and through this distance of 2000 miles 250 distinct
+signals were recorded and printed in one minute.</p>
+
+<p>First, as to the <i>Cable</i>. In the ordinary wires by the side of
+a railway the electric current travels on with the speed of lightning&mdash;uninterrupted
+by the speed of lightning; but when a
+wire is encased in gutta-percha, or any similar covering, for submersion<span class="pagenum"><a name="Page_227" id="Page_227">227</a></span>
+in the sea, new forces come into play. The electric excitement
+of the wire acts by induction, through the envelope,
+upon the particles of water in contact with that envelope, and
+calls up an electric force of an opposite kind. There are two
+forces, in fact, pulling against each other through the gutta-percha
+as a neutral medium,&mdash;that is, the electricity in the
+wire, and the opposite electricity in the film of water immediately
+surrounding the cable; and to that extent the power of
+the current in the enclosed wire is weakened. A submarine
+cable, when in the water, is virtually <i>a lengthened-out Leyden
+jar</i>; it transmits signals while being charged and discharged,
+instead of merely allowing a stream to flow evenly along it: it
+is a <i>bottle</i> for holding electricity rather than a <i>pipe</i> for carrying
+it; and this has to be filled for every time of using. The wire
+being carried underground, or through the water, the speed becomes
+quite measurable, say a thousand miles in a second, instead
+of two hundred thousand, owing to the retardation by induced
+or retrograde currents. The energy of the currents and
+the quality of the wire also affect the speed. Until lately it
+was supposed that the wire acts only as a <i>conductor</i> of electricity,
+and that a long wire must produce a weaker effect than a
+short one, on account of the consequent attenuation of the electrical
+influence; but it is now known that, the cable being a <i>reservoir</i>
+as well as a conductor, its electrical supply is increased
+in proportion to its length.</p>
+
+<p>The electro-magnetic current is employed, since it possesses
+a treble velocity of transmission, and realises consequently <i>a
+threefold working speed</i> as compared with simple voltaic electricity.
+Mr. Wildman Whitehouse has determined by his ingenious
+apparatus that the speed of the voltaic current might be
+raised under special circumstances to 1800 miles per second;
+but that of the induced current, or the electro-magnetic, might
+be augmented to 6000 miles per second.</p>
+
+<p>Next as to a <i>Quantity Battery</i> employed in these investigations.
+To effect a charge, and transmit a current through some
+thousand miles of the Atlantic Cable, Mr. Whitehouse had a
+piece of apparatus prepared consisting of twenty-five pairs of
+zinc and silver plates about the 20th part of a square inch
+large, and the pairs so arranged that they would hold a drop of
+acidulated water or brine between them. On charging this Lilliputian
+battery by dipping the plates in salt and water, messages
+were sent from it through a thousand miles of cable with
+the utmost ease; and not only so,&mdash;pair after pair was dropped
+out from the series, the messages being still sent on with equal
+facility, until at last only a single pair, charged by one single
+drop of liquid, was used. Strange to say, with this single pair
+and single drop distinct signals were effected through the thousand<span class="pagenum"><a name="Page_228" id="Page_228">228</a></span>
+miles of the cable! Each signal was registered at the end
+of the cable in less than three seconds of time.</p>
+
+<p>The entire length of wire, iron and copper, spun into the
+cable amounts to 332,500 miles, a length sufficient to engirdle
+the earth thirteen times. The cable weighs from 19 cwt. to a
+ton per mile, and will bear a strain of 5 tons.</p>
+
+<p>The <i>Perpetual Maintenance Battery</i>, for working the cable at
+the bottom of the sea, consists of large plates of platinated silver
+and amalgamated zinc, mounted in cells of gutta-percha.
+The zinc plates in each cell rest upon a longitudinal bar at the
+bottom, and the silver plates hang upon a similar bar at the top
+of the cell; so that there is virtually but a single stretch of
+silver and a single stretch of zinc in operation. Each of the
+ten cells contains 2000 square inches of acting surface; and
+the combination is so powerful, that when the broad strips of
+copper-plate which form the polar extensions are brought into
+contact or separated, brilliant flashes are produced, accompanied
+by a loud crackling sound. The points of large pliers are
+made red-hot in five seconds when placed between them, and
+even screws burn with vivid scintillation. The cost of maintaining
+this magnificent ten-celled Titan battery at work does
+not exceed a shilling per hour. The voltaic current generated
+in this battery is not, however, the electric stream to be sent
+across the Atlantic, but is only the primary power used to call
+up and stimulate the energy of a more speedy traveller by a
+complicated apparatus of “Double Induction Coils.” Nor is
+the transmission-current generated in the inner wire of the
+double induction coil,&mdash;and which becomes weakened when it
+has passed through 1800 or 1900 miles,&mdash;set to work to print or
+record the signals transmitted. This weakened current merely
+opens and closes the outlet of a fresh battery, which is to do
+the printing labour. This relay-instrument (as it is called),
+which consists of a temporary and permanent magnet, is so sensitive
+an apparatus, that it may be put in action by a fragment
+of zinc and a sixpence pressed against the tongue.</p>
+
+<p>The attempts to lay the cable in August 1857 failed through
+stretching it so tightly that it snapped and went to the bottom,
+at a depth of 12,000 feet, forty times the height of St. Paul’s.</p>
+
+<p>This great work was resumed in August 1858; and on the
+5th the first signals were received through <i>two thousand and
+fifty miles</i> of the Atlantic Cable. And it is worthy of remark,
+that just 111 years previously, on the 5th of August 1747, Dr.
+Watson astonished the scientific world by practically proving
+that the electric current could be transmitted through a <i>wire
+hardly two miles and a half long</i>.<a name="FNanchor_55" id="FNanchor_55" href="#Footnote_55" class="fnanchor">55</a></p>
+
+<hr />
+
+<p><span class="pagenum"><a name="Page_229" id="Page_229">229</a></span></p>
+
+<div class="chapter"></div>
+<h2><a name="Miscellanea" id="Miscellanea"></a>Miscellanea.</h2>
+
+<h3>HOW MARINE CHRONOMETERS ARE RATED AT THE ROYAL
+OBSERVATORY, GREENWICH.</h3>
+
+<p>The determination of the Longitude at Sea requires simply
+accurate instruments for the measurement of the positions of
+the heavenly bodies, and one or other of the two following,&mdash;either
+perfectly correct watches&mdash;or chronometers, as they are
+now called&mdash;or perfectly accurate tables of the lunar motions.</p>
+
+<p>So early as 1696 a report was spread among the members of
+the Royal Society that Sir Isaac Newton was occupied with the
+problem of finding the longitude at sea; but the rumour having
+no foundation, he requested Halley to acquaint the members
+“that he was not about it.”<a name="FNanchor_56" id="FNanchor_56" href="#Footnote_56" class="fnanchor">56</a> (<i>Sir David Brewster’s Life of
+Newton.</i>)</p>
+
+<p>In 1714 the legislature of Queen Anne passed an Act offering
+a reward of 20,000<i>l.</i> for the discovery of the longitude, the
+problem being then very inaccurately solved for want of good
+watches or lunar tables. About the year 1749, the attention
+of the Royal Society was directed to the improvements effected
+in the construction of watches by John Harrison, who received
+for his inventions the Copley Medal. Thus encouraged, Harrison
+continued his labours with unwearied diligence, and
+produced in 1758 a timekeeper which was sent for trial on a
+voyage to Jamaica. After 161 days the error of the instrument
+was only 1<sup>m</sup> 5<sup>s</sup>, and the maker received from the nation
+5000<i>l.</i> The Commissioners of the Board of Longitude subsequently
+required Harrison to construct under their inspection
+chronometers of a similar nature, which were subjected to
+trial in a voyage to Barbadoes, and performed with such accuracy,
+that, after having fully explained the principle of their
+construction to the commissioners, they awarded him 10,000<i>l.</i>
+more; at the same time Euler of Berlin and the heirs of Mayer
+of Göttingen received each 3000<i>l.</i> for their lunar tables.</p>
+
+<p><span class="pagenum"><a name="Page_230" id="Page_230">230</a></span></p>
+
+<blockquote>
+
+<p>The account of the trial of Harrison’s watch is very interesting. In
+April 1766, by desire of the Commissioners of the Board, the Lords of
+the Admiralty delivered the watch into the custody of the Astronomer-Royal,
+the Rev. Dr. Nevil Maskelyne. It was then placed at the Royal
+Observatory at Greenwich, in a box having two different locks, fixed to
+the floor or wainscot, with a plate of glass in the lid of the box, so that
+it might be compared as often as convenient with the regulator and the
+variation set down. The form observed by Mr. Harrison in winding up
+the watch was exactly followed; and an officer of Greenwich Hospital
+attended every day, at a stated hour, to see the watch wound up, and
+its comparison with the regulator entered. A key to one of the locks
+was kept at the Hospital for the use of the officer, and the other remained
+at the Observatory for the use of the Astronomer-Royal or his
+assistant.</p>
+
+<p>The watch was then tried in various positions till the beginning of
+July; and from thence to the end of February following in a horizontal
+position with its face upwards.</p>
+
+<p>The variation of the watch was then noted down, and a register was
+kept of the barometer and thermometer; and the time of comparing
+the same with the regulator was regularly kept, and attested by the
+Astronomer-Royal or his assistant and such of the officers as witnessed
+the winding-up and comparison of the watch.</p>
+
+<p>Under these conditions Harrison’s watch was received by the Astronomer-Royal
+at the Admiralty on May 5, 1766, in the presence of Philip
+Stephens, Esq., Secretary of the Admiralty; Captain Baillie, of the Royal
+Hospital, Greenwich; and Mr. Kendal the watchmaker, who accompanied
+the Astronomer-Royal to Greenwich, and saw the watch started
+and locked up in the box provided for it. The watch was then compared
+with the transit clock daily, and wound up in the presence of the
+officer of Greenwich Hospital. From May 5 to May 17 the watch was
+kept in a horizontal position with its face upwards; from May 18 to
+July 6 it was tried&mdash;first inclined at an angle of 20° to the horizon, with
+the face upwards, and the hours 12, 6, 3, and 9, highest successively;
+then in a vertical position, with the same hours highest in order; lastly,
+in a horizontal position with the face downwards. From July 16, 1766,
+to March 4, 1767, it was always kept in a horizontal position with its
+face upwards, lying upon the same cushion, and in the same box in
+which Mr. Harrison had kept it in the voyage to Barbadoes.</p>
+
+<p>From the observed transits of the sun over the meridian, according
+to the time of the regulator of the Observatory, together with the attested
+comparisons of Mr. Harrison’s watch with the transit clock, the
+watch was found too fast on several days as follows:</p>
+
+<table summary="Harrison's watch too fast">
+  <tr>
+    <td> </td>
+    <td> </td>
+    <td> </td>
+    <td class="tdc lrpad">h.</td>
+    <td class="tdr lrpad">m.</td>
+    <td class="tdc">s.</td></tr>
+  <tr>
+    <td class="tdl">1766.</td>
+    <td class="tdl">May 6</td>
+    <td class="tdc lrpad">too fast</td>
+    <td class="tdc">0</td>
+    <td class="tdr lrpad">0</td>
+    <td class="tdc">16·2</td></tr>
+  <tr>
+    <td> </td>
+    <td class="tdl">May 17</td>
+    <td class="tdc">”</td>
+    <td class="tdc">0</td>
+    <td class="tdr lrpad">3</td>
+    <td class="tdc">51·8</td></tr>
+  <tr>
+    <td> </td>
+    <td class="tdl">July 6</td>
+    <td class="tdc">”</td>
+    <td class="tdc">0</td>
+    <td class="tdr lrpad">14</td>
+    <td class="tdc">14·0</td></tr>
+  <tr>
+    <td> </td>
+    <td class="tdl">Aug. 6</td>
+    <td class="tdc">”</td>
+    <td class="tdc">0</td>
+    <td class="tdr lrpad">23</td>
+    <td class="tdc">58·4</td></tr>
+  <tr>
+    <td> </td>
+    <td class="tdl">Sept. 17</td>
+    <td class="tdc">”</td>
+    <td class="tdc">0</td>
+    <td class="tdr lrpad">32</td>
+    <td class="tdc">15·6</td></tr>
+  <tr>
+    <td> </td>
+    <td class="tdl">Oct. 29</td>
+    <td class="tdc">”</td>
+    <td class="tdc">0</td>
+    <td class="tdr lrpad">42</td>
+    <td class="tdc">20·9</td></tr>
+  <tr>
+    <td> </td>
+    <td class="tdl">Dec. 10</td>
+    <td class="tdc">”</td>
+    <td class="tdc">0</td>
+    <td class="tdr lrpad">54</td>
+    <td class="tdc">46·8</td></tr>
+  <tr>
+    <td class="tdl">1767.</td>
+    <td class="tdl">Jan. 21</td>
+    <td class="tdc">”</td>
+    <td class="tdc">1</td>
+    <td class="tdr lrpad">0</td>
+    <td class="tdc">28·6</td></tr>
+  <tr>
+    <td> </td>
+    <td class="tdl">March 4</td>
+    <td class="tdc">”</td>
+    <td class="tdc">1</td>
+    <td class="tdr lrpad">11</td>
+    <td class="tdc">23·0</td></tr>
+</table>
+
+<p>From May 6, which was the day after the watch arrived at the Royal
+Observatory, to March 4, 1767, there were six periods of six weeks each
+in which the watch was tried in a horizontal position; when the gaining
+in these several periods was as follows:</p>
+
+<p><span class="pagenum"><a name="Page_231" id="Page_231">231</a></span></p>
+
+<table id="watchgains" summary="Harrison's watch gains">
+  <tr>
+    <td class="tdl first">During the first 6 weeks</td>
+    <td class="tdc lrpad">it gained</td>
+    <td class="tdl">13<sup>m</sup></td>
+    <td class="tdl">20<sup>s</sup>,</td>
+    <td class="tdc lrpad">answering to</td>
+    <td class="tdl">3°</td>
+    <td class="tdl">20′</td>
+    <td class="tdc">of longitude.</td></tr>
+  <tr>
+    <td class="tdl first">In the 2d period of 6<br />weeks (from Aug. 6<br />to Sept. 17)</td>
+    <td class="tdc">”</td>
+    <td class="tdl"> 8</td>
+    <td class="tdl">17</td>
+    <td class="tdc">”</td>
+    <td class="tdl">2</td>
+    <td class="tdl"> 4</td>
+    <td class="tdc">”</td></tr>
+  <tr>
+    <td class="tdl first">In the 3d period (from<br />Sept. 17 to Oct. 29)</td>
+    <td class="tdc">”</td>
+    <td class="tdl">10</td>
+    <td class="tdl"> 5</td>
+    <td class="tdc">”</td>
+    <td class="tdl">2</td>
+    <td class="tdl">31</td>
+    <td class="tdc">”</td></tr>
+  <tr>
+    <td class="tdl first">In the 4th period (from<br />Oct. 29 to Dec. 20)</td>
+    <td class="tdc">”</td>
+    <td class="tdl">12</td>
+    <td class="tdl">26</td>
+    <td class="tdc">”</td>
+    <td class="tdl">3</td>
+    <td class="tdl"> 6</td>
+    <td class="tdc">”</td></tr>
+  <tr>
+    <td class="tdl first">In the 5th period (from<br />Dec. 20 to Jan. 21)</td>
+    <td class="tdc">”</td>
+    <td class="tdl"> 5</td>
+    <td class="tdl">42</td>
+    <td class="tdc">”</td>
+    <td class="tdl">1</td>
+    <td class="tdl">25</td>
+    <td class="tdc">”</td></tr>
+  <tr>
+    <td class="tdl first">In the 6th period (from<br />Jan. 21 to Mar. 4)</td>
+    <td class="tdc">”</td>
+    <td class="tdl">10</td>
+    <td class="tdl">54</td>
+    <td class="tdc">”</td>
+    <td class="tdl">2</td>
+    <td class="tdl">43</td>
+    <td class="tdc">”</td></tr>
+</table>
+</blockquote>
+
+<p>It was thence concluded that Mr. Harrison’s watch could
+not be depended upon to keep the longitude within a West-India
+voyage of six weeks, nor to keep the longitude within
+half a degree for more than a fortnight; and that it must be
+kept in a place where the temperature was always some degrees
+above freezing.<a name="FNanchor_57" id="FNanchor_57" href="#Footnote_57" class="fnanchor">57</a> (However, Harrison’s watch, which was made
+by Mr. Kendal subsequently, succeeded so completely, that after
+it had been round the world with Captain Cook, in the years
+1772&ndash;1775, the second 10,000<i>l.</i> was given to Harrison.)</p>
+
+<p>In the Act of 12th Queen Anne, the comparison of chronometers
+was not mentioned in reference to the Observatory duties;
+but after this time they became a serious charge upon the Observatory,
+which, it must be admitted, is by far the best place
+to try chronometers: the excellence of the instruments, and the
+frequent observations of the heavenly bodies over the meridian,
+will always render the rate of going of the Observatory clock
+better known than can be expected of the clock in most other
+places.</p>
+
+<p>After Mr. Harrison’s watch was tried, some watches by Earnshaw,
+Mudge, and others, were rated and examined by the Astronomer-Royal.</p>
+
+<p>At the Royal Observatory, Greenwich, there are frequently
+above 100 chronometers being rated, and there have been as
+many as 170 at one time. They are rated daily by two observers,
+the process being as follows. At a certain time every
+day two assistants in charge repair to the chronometer-room,
+where is a time-piece set to true time; one winds up each with
+its own key, and the second follows after some little time and
+verifies the fact that each is wound. One assistant then looks
+at each watch in succession, counting the beats of the clock
+whilst he compares the chronometer by the eye; and in the
+course of a few seconds he calls out the second shown by the
+chronometer when the clock is at a whole minute. This number
+is entered in a book by the other assistant, and so on till
+all the chronometers are compared. Then the assistants change<span class="pagenum"><a name="Page_232" id="Page_232">232</a></span>
+places, the second comparing and the first writing down. From
+these daily comparisons the daily rates are deduced, by which
+the goodness of the watch is determined. The errors are of
+two classes&mdash;that of general bad workmanship, and that of
+over or under correction for temperature. In the room is an
+apparatus in which the watch may be continually kept at temperatures
+exceeding 100° by artificial heat; and outside the
+window of the room is an iron cage, in which they are subjected
+to low temperatures. The very great care taken with all chronometers
+sent to the Royal Observatory, as well as the perfect
+impartiality of the examination which each receives, afford
+encouragement to their manufacture, and are of the utmost
+importance to the safety and perfection of navigation.</p>
+
+<p>We have before us now the Report of the Astronomer-Royal
+on the Rates of Chronometers in the year 1854, in which the
+following are the successive weekly sums of the daily rates of
+the first there mentioned:</p>
+
+<table id="report" summary="Report of the Astronomer-Royal">
+  <tr>
+    <td class="tdl" colspan="3">Week ending</td>
+    <td class="tdc">secs.</td></tr>
+  <tr>
+    <td class="tdc">Jan.</td>
+    <td class="tdr">21,</td>
+    <td class="tdc lrpad">loss in the week</td>
+    <td class="tdc">2·2</td></tr>
+  <tr>
+    <td class="tdc">”</td>
+    <td class="tdr rpad">28</td>
+    <td class="tdc">”</td>
+    <td class="tdc">4·0</td></tr>
+  <tr>
+    <td class="tdc">Feb.</td>
+    <td class="tdr rpad">4</td>
+    <td class="tdc">”</td>
+    <td class="tdc">1·1</td></tr>
+  <tr>
+    <td class="tdc">”</td>
+    <td class="tdr rpad">11</td>
+    <td class="tdc">”</td>
+    <td class="tdc">5·0</td></tr>
+  <tr>
+    <td class="tdc">”</td>
+    <td class="tdr rpad">18</td>
+    <td class="tdc">”</td>
+    <td class="tdc">4·9</td></tr>
+  <tr>
+    <td class="tdc">”</td>
+    <td class="tdr rpad">25</td>
+    <td class="tdc">”</td>
+    <td class="tdc">5·5</td></tr>
+  <tr>
+    <td class="tdc">Mar.</td>
+    <td class="tdr rpad">4</td>
+    <td class="tdc">”</td>
+    <td class="tdc">6·0</td></tr>
+  <tr>
+    <td class="tdc">”</td>
+    <td class="tdr rpad">11</td>
+    <td class="tdc">”</td>
+    <td class="tdc">6·0</td></tr>
+  <tr>
+    <td class="tdc">”</td>
+    <td class="tdr rpad">18</td>
+    <td class="tdc">”</td>
+    <td class="tdc">1·5</td></tr>
+  <tr>
+    <td class="tdc">”</td>
+    <td class="tdr rpad">25</td>
+    <td class="tdc">”</td>
+    <td class="tdc">4·5</td></tr>
+  <tr>
+    <td class="tdc">Apr.</td>
+    <td class="tdr rpad">1</td>
+    <td class="tdc">”</td>
+    <td class="tdc">4·0</td></tr>
+  <tr>
+    <td class="tdc">”</td>
+    <td class="tdr rpad">8</td>
+    <td class="tdc">”</td>
+    <td class="tdc">1·5</td></tr>
+  <tr>
+    <td class="tdc">”</td>
+    <td class="tdr">15,</td>
+    <td class="tdc">gain in the week</td>
+    <td class="tdc">0·4</td></tr>
+  <tr>
+    <td class="tdc">Apr.</td>
+    <td class="tdr">22,</td>
+    <td class="tdc">”</td>
+    <td class="tdc">2·6</td></tr>
+  <tr>
+    <td class="tdc">”</td>
+    <td class="tdr">29,</td>
+    <td class="tdc">loss in the week</td>
+    <td class="tdc">1·4</td></tr>
+  <tr>
+    <td class="tdc">May</td>
+    <td class="tdr rpad">6</td>
+    <td class="tdc">”</td>
+    <td class="tdc">2·1</td></tr>
+  <tr>
+    <td class="tdc">”</td>
+    <td class="tdr rpad">13</td>
+    <td class="tdc">”</td>
+    <td class="tdc">3·0</td></tr>
+  <tr>
+    <td class="tdc">”</td>
+    <td class="tdr rpad">20</td>
+    <td class="tdc">”</td>
+    <td class="tdc">5·1</td></tr>
+  <tr>
+    <td class="tdc">”</td>
+    <td class="tdr rpad">27</td>
+    <td class="tdc">”</td>
+    <td class="tdc">3·3</td></tr>
+  <tr>
+    <td class="tdc">June</td>
+    <td class="tdr rpad">3</td>
+    <td class="tdc">”</td>
+    <td class="tdc">2·8</td></tr>
+  <tr>
+    <td class="tdc">”</td>
+    <td class="tdr rpad">10</td>
+    <td class="tdc">”</td>
+    <td class="tdc">1·8</td></tr>
+  <tr>
+    <td class="tdc">”</td>
+    <td class="tdr rpad">17</td>
+    <td class="tdc">”</td>
+    <td class="tdc">2·0</td></tr>
+  <tr>
+    <td class="tdc">”</td>
+    <td class="tdr rpad">24</td>
+    <td class="tdc">”</td>
+    <td class="tdc">3·0</td></tr>
+  <tr>
+    <td class="tdc">July</td>
+    <td class="tdr rpad">1</td>
+    <td class="tdc">”</td>
+    <td class="tdc">2·5</td></tr>
+  <tr>
+    <td class="tdc">”</td>
+    <td class="tdr rpad">8</td>
+    <td class="tdc">”</td>
+    <td class="tdc">1·2</td></tr>
+</table>
+
+<p>Till February 4 the watch was exposed to the external air
+outside a north window; from February 5 to March 4 it was
+placed in the chamber of a stove heated by gas to a moderate
+temperature; and from April 29 to May 20 it was placed in the
+chamber when heated to a high temperature.</p>
+
+<p>The advance in making chronometers since Harrison’s celebrated
+watch was tried at the Royal Observatory, more than
+ninety years since, may be judged by comparing its rates with
+those above.</p>
+
+<h3>GEOMETRY OF SHELLS.</h3>
+
+<p>There is a mechanical uniformity observable in the description
+of shells of the same species which at once suggests the
+probability that the generating figure of each increases, and
+that the spiral chamber of each expands itself, according to some
+simple geometrical law common to all. To the determination
+of this law the operculum lends itself, in certain classes of
+shells, with remarkable facility. Continually enlarged by the
+animal, as the construction of its shell advances so as to fill up<span class="pagenum"><a name="Page_233" id="Page_233">233</a></span>
+its mouth, the operculum measures the progressive widening of
+the spiral chamber by the progressive stages of its growth.</p>
+
+<div class="tb">* <span class="in2">* </span><span class="in2">* </span><span class="in2">* </span><span class="in2">*</span></div>
+
+<p>The animal, as he advances in the construction of his shell,
+increases continually his operculum, so as to adjust it to his
+mouth. He increases it, however, not by additions made at the
+same time all round its margin, but by additions made only on
+one side of it at once. One edge of the operculum thus remains
+unaltered as it is advanced into each new position, and
+placed in a newly-formed section of the chamber similar to the
+last but greater than it.</p>
+
+<p>That the same edge which fitted a portion of the first less
+section should be capable of adjustment so as to fit a portion
+of the next similar but greater section, supposes a geometrical
+provision in the curved form of the chamber of great complication
+and difficulty. But God hath bestowed upon this
+humble architect the practical skill of the learned geometrician;
+and he makes this provision with admirable precision in
+that curvature of the logarithmic spiral which he gives to the
+section of the shell. This curvature obtaining, he has only
+to turn his operculum slightly round in its own place, as he
+advances it into each newly-formed portion of his chamber, to
+adapt one margin of it to a new and larger surface and a different
+curvature, leaving the space to be filled up by increasing
+the operculum wholly on the outer margin.</p>
+
+<div class="tb">* <span class="in2">* </span><span class="in2">* </span><span class="in2">* </span><span class="in2">*</span></div>
+
+<p>Why the Mollusks, who inhabit turbinated and discoid shells,
+should, in the progressive increase of their spiral dwellings, affect
+the peculiar law of the logarithmic spiral, is easily to be
+understood. Providence has subjected the instinct which
+shapes out each to a rigid uniformity of operation.&mdash;<i>Professor
+Mosely</i>: <i>Philos. Trans.</i> 1838.</p>
+
+<h3>HYDRAULIC THEORY OF SHELLS.</h3>
+
+<p>How beautifully is the wisdom of God developed in shaping
+out and moulding shells! and especially in the particular value
+of the constant angle which the spiral of each species of shell
+affects,&mdash;a value connected by a necessary relation with the
+economy of the material of each, and with its stability and
+the conditions of its buoyancy. Thus the shell of the <i>Nautilus
+Pompilius</i> has, hydrostatically, an A-statical surface. If placed
+with any portion of its surface upon the water, it will immediately
+turn over towards its smaller end, and rest only on its
+mouth. Those conversant with the theory of floating bodies
+will recognise in this an interesting property.&mdash;<i>Ibid.</i></p>
+
+<p><span class="pagenum"><a name="Page_234" id="Page_234">234</a></span></p>
+
+<h3>SERVICES OF SEA-SHELLS AND ANIMALCULES.</h3>
+
+<p>Dr. Maury is disposed to regard these beings as having much
+to do in maintaining the harmonies of creation, and the principles
+of the most admirable compensation in the system of
+oceanic circulation. “We may even regard them as regulators,
+to some extent, of climates in parts of the earth far removed
+from their presence. There is something suggestive
+both of the grand and the beautiful in the idea that while the
+insects of the sea are building up their coral islands in the perpetual
+summer of the tropics, they are also engaged in dispensing
+warmth to distant parts of the earth, and in mitigating the
+severe cold of the polar winter.”</p>
+
+<h3>DEPTH OF THE PRIMEVAL SEAS.</h3>
+
+<p>Professor Forbes, in a communication to the Royal Society,
+states that not only the colour of the shells of existing mollusks
+ceases to be strongly marked at considerable depths, but also
+that well-defined patterns are, with very few and slight exceptions,
+presented only by testacea inhabiting the littoral, circumlittoral,
+and median zones. In the Mediterranean, only one in
+eighteen of the shells taken from below 100 fathoms exhibit
+any markings of colour, and even the few that do so are questionable
+inhabitants of those depths. Between 30 and 35 fathoms,
+the proportion of marked to plain shells is rather less
+than one in three; and between the margin and two fathoms
+the striped or mottled species exceed one-half of the total number.
+In our own seas, Professor Forbes observes that testacea
+taken from below 100 fathoms, even when they are individuals
+of species vividly striped or banded in shallower zones, are quite
+white or colourless. At between 60 and 80 fathoms, striping
+and banding are rarely presented by our shells, especially in the
+northern provinces; from 50 fathoms, shallow bands, colours,
+and patterns, are well marked. <i>The relation of these arrangements
+of colour to the degree of light penetrating the different zones
+of depth</i> is a subject well worthy of minute inquiry.</p>
+
+<h3>NATURAL WATER-PURIFIERS.</h3>
+
+<p>Mr. Warrington kept for a whole year twelve gallons of water
+in a state of admirably balanced purity by the following beautiful
+action:</p>
+
+<blockquote>
+
+<p>In the tank, or aquarium, were two gold fish, six water-snails, and
+two or three specimens of that elegant aquatic plant <i>Valisperia sporalis</i>,
+which, before the introduction of the water-snails, by its decayed
+leaves caused a growth of slimy mucus, and made the water turbid and
+likely to destroy both plants and fish. But under the improved arrangement
+the slime, as fast as it was engendered, was consumed by
+the water-snails, which reproduced it in the shape of young snails, which<span class="pagenum"><a name="Page_235" id="Page_235">235</a></span>
+furnished a succulent food to the fish. Meanwhile the <i>Valisperia</i> plants
+absorbed the carbonic acid exhaled by the respiration of their companions,
+fixing the carbon in their growing stems and luxuriant blossoms,
+and refreshing the oxygen (during sunshine in visible little streams) for
+the respiration of the snails and the fish. The spectacle of perfect equilibrium
+thus simply maintained between animal, vegetable, and inorganic
+activity, was strikingly beautiful; and such means might possibly
+hereafter be made available on a large scale for keeping tanked water
+sweet and clean.&mdash;<i>Quarterly Review</i>, 1850.</p></blockquote>
+
+<h3>HOW TO IMITATE SEA-WATER.</h3>
+
+<p>The demand for Sea-water to supply the Marine Aquarium&mdash;now
+to be seen in so many houses&mdash;induced Mr. Gosse to attempt
+the manufacture of Sea-water, more especially as the
+constituents are well known. He accordingly took Scheveitzer’s
+analysis of Sea-water for his guide. In one thousand
+grains of sea-water taken off Brighton, it gave: water, 964·744;
+chloride of sodium, 27·059; chloride of magnesium, 3·666;
+chloride of potassium, 9·755; bromide of magnesium, 0·29;
+sulphate of magnesia, 2·295; sulphate of lime, 1·407; carbonate
+of lime, 0·033: total, 999·998. Omitting the bromide of
+magnesium, the carbonate of lime, and the sulphate of lime, as
+being very small quantities, the component parts were reduced
+to common salt, 3½ oz.; Epsom salts, ¼ oz.; chloride of magnesium,
+200 grains troy; chloride of potassium, 40 grains
+troy; and four quarts of water. Next day the mixture was
+filtered through a sponge into a glass jar, the bottom covered
+with shore-pebbles and fragments of stone and fronds of green
+sea-weed. A coating of green spores was soon deposited on the
+sides of the glass, and bubbles of oxygen were copiously thrown
+off every day under the excitement of the sun’s light. In a
+week Mr. Gosse put in species of <i>Actinia Bowerbankia</i>, <i>Cellularia</i>,
+<i>Serpula</i>, &amp;c. with some red sea-weeds; and the whole
+throve well.</p>
+
+<h3>VELOCITY OF IMPRESSIONS TRANSMITTED TO THE BRAIN.</h3>
+
+<p>Professor Helmholtz of Königsberg has, by the electro-magnetic
+method,<a name="FNanchor_58" id="FNanchor_58" href="#Footnote_58" class="fnanchor">58</a> ascertained that the intelligence of an impression
+made upon the ends of the nerves in communication
+with the skin is transmitted to the brain with a velocity of
+about 195 feet per second. Arrived at the brain, about one-tenth
+of a second passes before the will is able to give the command
+to the nerves that certain muscles shall execute a certain
+motion, varying in persons and times. Finally, about 1/100th<span class="pagenum"><a name="Page_236" id="Page_236">236</a></span>
+of a second passes after the receipt of the command before the
+muscle is in activity. In all, therefore, from the excitation
+of the sensitive nerves till the moving of the muscle, 1¼ to 2/10ths
+of a second are consumed. Intelligence from the great toe arrives
+about 1/30th of a second later than from the ear or the face.</p>
+
+<p>Thus we see that the differences of time in the nervous impressions,
+which we are accustomed to regard as simultaneous,
+lie near our perception. We are taught by astronomy that, on
+account of the time taken to propagate light, we now see what
+has occurred in the fixed stars years ago; and that, owing to
+the time required for the transmission of sound, we hear after
+we see is a matter of daily experience. Happily the distances
+to be traversed by our sensuous perceptions before they reach
+the brain are so short that we do not observe their influence,
+and are therefore unprejudiced in our practical interest. With
+an ordinary whale the case is perhaps more dubious; for in all
+probability the animal does not feel a wound near its tail until
+a second after it has been inflicted, and requires another second
+to send the command to the tail to defend itself.</p>
+
+<h3>PHOTOGRAPHS ON THE RETINA.</h3>
+
+<p>The late Rev. Dr. Scoresby explained with much minuteness
+and skill the varying phenomena which presented themselves
+to him after gazing intently for some time on strongly-illuminated
+objects,&mdash;as the sun, the moon, a red or orange or
+yellow wafer on a strongly-contrasted ground, or a dark object
+seen in a bright field. The doctor explained, upon removing
+the eyes from the object, the early appearance of the picture or
+image which had been thus “photographed on the Retina,”
+with the photochromatic changes which the picture underwent
+while it still retained its general form and most strongly-marked
+features; also, how these pictures, when they had almost faded
+away, could at pleasure, and for a considerable time, be renewed
+by rapidly opening and shutting the eyes.</p>
+
+<h3>DIRECT EXPLORATION OF THE INTERIOR OF THE EYE.</h3>
+
+<p>Dr. S. Wood of Cincinnati states, that by means of a small
+double convex lens of short focus held near the eye,&mdash;that organ
+looking through it at a candle twelve or fifteen feet distant,&mdash;there
+will be perceived a large luminous disc, covered with
+dark and light spots and dark streaks, which, after a momentary
+confusion, will settle down into an unchanging picture,
+which picture is composed of the organs or internal parts of the
+eye. The eye is thus enabled to view its own internal organisation,
+to have a beautiful exhibition of the vessels of the cornea,
+of the distribution of the lachrymas secretions in the act<span class="pagenum"><a name="Page_237" id="Page_237">237</a></span>
+of winking, and to see into the nature and cause of <i>muscæ volitantes</i>.</p>
+
+<h3>NATURE OF THE CANDLE-FLAME.</h3>
+
+<p>M. Volger has subjected this Flame to a new analysis.</p>
+
+<blockquote>
+
+<p>He finds that the so-called <i>flame-bud</i>, a globular blue flaminule, is
+first produced at the summit of the wick: this is the result of the combustion
+of carbonic oxide, hydrogen, and carbon, and is surrounded by
+a reddish-violet halo, the <i>veil</i>. The increased heat now gives rise to
+the actual flame, which shoots forth from the expanding bud, and is
+then surrounded at its inferior portion only by the latter. The interior
+consists of a dark gaseous cone, containing the immediate products of
+the decomposition of the fatty acids, and surrounded by another dark
+hollow cone, the <i>inner cap</i>. Here we already meet with carbon and
+hydrogen, which have resulted from the process of decomposition; and
+we distinguish this cone from the inner one by its yielding soot. The
+<i>external cap</i> constitutes the most luminous portion of the flame, in which
+the hydrogen is consumed and the carbon rendered incandescent. The
+surrounding portion is but slightly luminous, deposits no soot, and in it
+the carbon and hydrogen are consumed.&mdash;<i>Liebig’s Annual Report.</i></p></blockquote>
+
+<h3>HOW SOON A CORPSE DECAYS.</h3>
+
+<p>Mr. Lewis, of the General Board of Health, from his examination
+of the contents of nearly 100 coffins in the vaults and
+catacombs of London churches, concludes that the complete
+decomposition of a corpse, and its resolution into its ultimate
+elements, takes place in a leaden coffin with extreme slowness.
+In a wooden coffin the remains, with the exception of the bones,
+vanish in from two to five years. This period depends upon the
+quality of the wood, and the free access of air to the coffins.
+But in leaden coffins, 50, 60, 80, and even 100 years are required
+to accomplish this. “I have opened,” says Mr. Lewis,
+“a coffin in which the corpse had been placed for nearly a century;
+and the ammoniacal gas formed dense white fumes when
+brought in contact with hydrochloric-acid gas, and was so powerful
+that the head could not remain in it for more than a few
+seconds at a time.” To render the human body perfectly inert
+after death, it should be placed in a light wooden coffin, in a
+pervious soil, from five to eight feet deep.</p>
+
+<h3>MUSKET-BALLS FOUND IN IVORY.</h3>
+
+<p>The Ceylon sportsman, in shooting elephants, aims at a spot
+just above the proboscis. If he fires a little too low, the ball
+passes into the tusk-socket, causing great pain to the animal,
+but not endangering its life; and it is immediately surrounded
+by osteo-dentine. It has often been a matter of wonder how
+such bodies should become completely imbedded in the substance
+of the tusk, sometimes without any visible aperture; or
+how leaden bullets become lodged in the solid centre of a very<span class="pagenum"><a name="Page_238" id="Page_238">238</a></span>
+large tusk without having been flattened, as they are found by
+the ivory-turner.</p>
+
+<blockquote>
+
+<p>The explanation is as follows: A musket-ball aimed at the head of
+an elephant may penetrate the thin bony socket and the thinner ivory
+parietes of the wide conical pulp-cavity occupying the inserted base of
+the tusk; if the projectile force be there spent, the ball will gravitate
+to the opposite and lower side of the pulp-cavity. The pulp becomes
+inflamed, irregular calcification ensues, and osteo-dentine is formed
+around the ball. The pulp then resumes its healthy state and functions,
+and coats the osteo-dentine enclosing the ball, together with the root of
+the conical cavity into which the mass projects, with layers of normal
+ivory. The hole formed by the ball is soon replaced, and filled up by
+osteo-dentine, and coated with cement. Meanwhile, by the continued
+progress of growth, the enclosed ball is pushed forward to the middle of
+the solid tusk; or if the elephant be young, the ball may be carried
+forward by growth and wear of the tusk until its base has become the
+apex, and become finally exposed and discharged by the continual abrasion
+to which the apex of the tusk is subjected.&mdash;<i>Professor Owen.</i></p></blockquote>
+
+<h3>NATURE OF THE SUN.</h3>
+
+<p>To the article at pp. 59&ndash;60 should be added the result obtained
+by Dr. Woods of Parsonstown, and communicated to the
+<i>Philosophical Magazine</i> for July 1854. Dr. Woods, from photographic
+experiment, has no doubt that the light from the centre
+of flame acts more energetically than that from the edge on a
+surface capable of receiving its impression; and that light from
+a luminous solid body acts equally powerfully from its centre
+or its edges: wherefore Dr. Woods concludes that, as the sun
+affects a sensitive plate similarly with flame, it is probable its
+light-producing portion is of a similar nature.</p>
+
+<blockquote>
+
+<p><i>Note to</i> “<span class="smcap">Is the Heat of the Sun decreasing?</span>” <i>at page 65</i>.&mdash;Dr.
+Vaughan of Cincinnati has stated to the British Association:
+“From a comparison of the relative intensity of solar, lunar, and artificial
+light, as determined by Euler and Wollaston, it appears that the
+rays of the sun have an illuminating power equal to that of 14,000 candles
+at a distance of one foot, or of 3500,000000,000000,000000,000000
+candles at a distance of 95,000,000 miles. It follows that the amount
+of light which flows from the solar orb could be scarcely produced by
+the daily combustion of 200 globes of tallow, each equal to the earth in
+magnitude. A sphere of combustible matter much larger than the sun
+itself should be consumed every ten years in maintaining its wonderful
+brilliancy; and its atmosphere, if pure oxygen, would be expended before
+a few days in supporting so great a conflagration. An illumination
+on so vast a scale could be kept up only by the inexhaustible magazine
+of ether disseminated through space, and ever ready to manifest its luciferous
+properties on large spheres, whose attraction renders it sufficiently
+dense for the play of chemical affinity. Accordingly suns derive
+the power of shedding perpetual light, not from their chemical
+constitution, but from their immense mass and their superior attractive
+power.”</p></blockquote>
+
+<p><span class="pagenum"><a name="Page_239" id="Page_239">239</a></span></p>
+
+<h3>PLANETOIDS.</h3>
+
+<table id="planetoids" summary="Discoveries of the Planetoids">
+  <tr class="hdr smaller">
+    <td class="tdc bt bb">Name.</td>
+    <td class="tdc bt bb">Date of<br />Discovery.</td>
+    <td class="tdc bt bb">Discoverer.</td>
+    <td class="tdc bt bb">Place of<br />Discovery.</td>
+    <td class="tdc bt bb">No. discovered<br />by each<br />astronomer.</td></tr>
+  <tr>
+    <td class="tdl">Mercury, Mars,<br />Venus, Jupiter,<br />Earth, Saturn</td>
+    <td class="tdc">Known to the<br />ancients.</td>
+    <td class="tdc">...</td>
+    <td class="tdc">...</td>
+    <td class="tdc">&mdash;</td></tr>
+  <tr>
+    <td class="tdl">   Uranus</td>
+    <td class="tdl">1781, March 13</td>
+    <td class="tdl">W. Herschel</td>
+    <td class="tdl">Bath</td>
+    <td class="tdc">&mdash;</td></tr>
+  <tr>
+    <td class="tdl">   Neptune<a name="FNanchor_59" id="FNanchor_59" href="#Footnote_59" class="fnanchor">59</a></td>
+    <td class="tdl">1846, Sept. 23</td>
+    <td class="tdl">Galle</td>
+    <td class="tdl">Berlin</td>
+    <td class="tdc">&mdash;</td></tr>
+  <tr>
+    <td class="tdl"> 1 Ceres</td>
+    <td class="tdl">1801, Jan. 1</td>
+    <td class="tdl">Piazzi</td>
+    <td class="tdl">Palermo</td>
+    <td class="tdc">1</td></tr>
+  <tr>
+    <td class="tdl"> 2 Pallas</td>
+    <td class="tdl">1802, March 28</td>
+    <td class="tdl">Olbers</td>
+    <td class="tdl">Bremen</td>
+    <td class="tdc">1</td></tr>
+  <tr>
+    <td class="tdl"> 3 Juno</td>
+    <td class="tdl">1804, Sept. 1</td>
+    <td class="tdl">Harding</td>
+    <td class="tdl">Lilienthal</td>
+    <td class="tdc">1</td></tr>
+  <tr>
+    <td class="tdl"> 4 Vesta</td>
+    <td class="tdl">1807, March 29</td>
+    <td class="tdl">Olbers</td>
+    <td class="tdl">Bremen</td>
+    <td class="tdc">2</td></tr>
+  <tr>
+    <td class="tdl"> 5 Astræa</td>
+    <td class="tdl">1845, Dec. 8</td>
+    <td class="tdl">Encke</td>
+    <td class="tdl">Driesen</td>
+    <td class="tdc">1</td></tr>
+  <tr>
+    <td class="tdl"> 6 Hebe</td>
+    <td class="tdl">1847, July 1</td>
+    <td class="tdl">Encke</td>
+    <td class="tdl">Driesen</td>
+    <td class="tdc">2</td></tr>
+  <tr>
+    <td class="tdl"> 7 Iris</td>
+    <td class="tdl">1847, August 13</td>
+    <td class="tdl">Hind</td>
+    <td class="tdl">London</td>
+    <td class="tdc">1</td></tr>
+  <tr>
+    <td class="tdl"> 8 Flora</td>
+    <td class="tdl">1847, Oct. 18</td>
+    <td class="tdl">Hind</td>
+    <td class="tdl">London</td>
+    <td class="tdc">2</td></tr>
+  <tr>
+    <td class="tdl"> 9 Metis</td>
+    <td class="tdl">1848, April 25</td>
+    <td class="tdl">Graham</td>
+    <td class="tdl">Markree</td>
+    <td class="tdc">1</td></tr>
+  <tr>
+    <td class="tdl">10 Hygeia</td>
+    <td class="tdl">1849, April 12</td>
+    <td class="tdl">Gasperis</td>
+    <td class="tdl">Naples</td>
+    <td class="tdc">1</td></tr>
+  <tr>
+    <td class="tdl">11 Parthenope</td>
+    <td class="tdl">1850, May 11</td>
+    <td class="tdl">Gasperis</td>
+    <td class="tdl">Naples</td>
+    <td class="tdc">2</td></tr>
+  <tr>
+    <td class="tdl">12 Victoria</td>
+    <td class="tdl">1850, Sept. 13</td>
+    <td class="tdl">Hind</td>
+    <td class="tdl">London</td>
+    <td class="tdc">3</td></tr>
+  <tr>
+    <td class="tdl">13 Egeria</td>
+    <td class="tdl">1850, Nov. 2</td>
+    <td class="tdl">Gasperis</td>
+    <td class="tdl">Naples</td>
+    <td class="tdc">3</td></tr>
+  <tr>
+    <td class="tdl">14 Irene</td>
+    <td class="tdl">1851, May 19</td>
+    <td class="tdl">Hind</td>
+    <td class="tdl">London</td>
+    <td class="tdc">4</td></tr>
+  <tr>
+    <td class="tdl">15 Eunomia</td>
+    <td class="tdl">1851, July 29</td>
+    <td class="tdl">Gasperis</td>
+    <td class="tdl">Naples</td>
+    <td class="tdc">4</td></tr>
+  <tr>
+    <td class="tdl">16 Psyche</td>
+    <td class="tdl">1852, March 17</td>
+    <td class="tdl">Gasperis</td>
+    <td class="tdl">Naples</td>
+    <td class="tdc">5</td></tr>
+  <tr>
+    <td class="tdl">17 Thetis</td>
+    <td class="tdl">1852, April 17</td>
+    <td class="tdl">Luther</td>
+    <td class="tdl">Bilk</td>
+    <td class="tdc">1</td></tr>
+  <tr>
+    <td class="tdl">18 Melpomene</td>
+    <td class="tdl">1852, June 24</td>
+    <td class="tdl">Hind</td>
+    <td class="tdl">London</td>
+    <td class="tdc">5</td></tr>
+  <tr>
+    <td class="tdl">19 Fortuna</td>
+    <td class="tdl">1852, August 22</td>
+    <td class="tdl">Hind</td>
+    <td class="tdl">London</td>
+    <td class="tdc">6</td></tr>
+  <tr>
+    <td class="tdl">20 Massilia</td>
+    <td class="tdl">1852, Sept. 19</td>
+    <td class="tdl">Gasperis</td>
+    <td class="tdl">Naples</td>
+    <td class="tdc">6</td></tr>
+  <tr>
+    <td class="tdl">21 Lutetia</td>
+    <td class="tdl">1852, Nov. 15</td>
+    <td class="tdl">Goldschmidt</td>
+    <td class="tdl">Paris</td>
+    <td class="tdc">1</td></tr>
+  <tr>
+    <td class="tdl">22 Calliope</td>
+    <td class="tdl">1852, Nov. 16</td>
+    <td class="tdl">Hind</td>
+    <td class="tdl">London</td>
+    <td class="tdc">7</td></tr>
+  <tr>
+    <td class="tdl">23 Thalia</td>
+    <td class="tdl">1852, Dec. 15</td>
+    <td class="tdl">Hind</td>
+    <td class="tdl">London</td>
+    <td class="tdc">8</td></tr>
+  <tr>
+    <td class="tdl">24 Themis</td>
+    <td class="tdl">1853, April 5</td>
+    <td class="tdl">Gasperis</td>
+    <td class="tdl">Naples</td>
+    <td class="tdc">7</td></tr>
+  <tr>
+    <td class="tdl">25 Phocea</td>
+    <td class="tdl">1853, April 6</td>
+    <td class="tdl">Chacornac</td>
+    <td class="tdl">Marseilles</td>
+    <td class="tdc">1</td></tr>
+  <tr>
+    <td class="tdl">26 Proserpine</td>
+    <td class="tdl">1853, May 5</td>
+    <td class="tdl">Luther</td>
+    <td class="tdl">Bilk</td>
+    <td class="tdc">2</td></tr>
+  <tr>
+    <td class="tdl">27 Euterpe</td>
+    <td class="tdl">1853, Nov. 8</td>
+    <td class="tdl">Hind</td>
+    <td class="tdl">London</td>
+    <td class="tdc">9</td></tr>
+  <tr>
+    <td class="tdl">28 Bellona</td>
+    <td class="tdl">1854, March 1</td>
+    <td class="tdl">Luther</td>
+    <td class="tdl">Bilk</td>
+    <td class="tdc">3</td></tr>
+  <tr>
+    <td class="tdl">29 Amphitrite</td>
+    <td class="tdl">1854, March 1</td>
+    <td class="tdl">Marth</td>
+    <td class="tdl">London</td>
+    <td class="tdc">1</td></tr>
+  <tr>
+    <td class="tdl">30 Urania</td>
+    <td class="tdl">1854, July 22</td>
+    <td class="tdl">Hind</td>
+    <td class="tdl">London</td>
+    <td class="tdc">10 </td></tr>
+  <tr>
+    <td class="tdl">31 Euphrosyne</td>
+    <td class="tdl">1854, Sept. 1</td>
+    <td class="tdl">Furguson</td>
+    <td class="tdl">Washington</td>
+    <td class="tdc">1</td></tr>
+  <tr>
+    <td class="tdl">32 Pomona</td>
+    <td class="tdl">1854, Oct. 26</td>
+    <td class="tdl">Goldschmidt</td>
+    <td class="tdl">Paris</td>
+    <td class="tdc">2</td></tr>
+  <tr>
+    <td class="tdl">33 Polyhymnia</td>
+    <td class="tdl">1854, Oct. 28</td>
+    <td class="tdl">Chacornac</td>
+    <td class="tdl">Paris</td>
+    <td class="tdc">2</td></tr>
+  <tr>
+    <td class="tdl">34 Circe</td>
+    <td class="tdl">1855, April 6</td>
+    <td class="tdl">Chacornac</td>
+    <td class="tdl">Paris</td>
+    <td class="tdc">3</td></tr>
+  <tr>
+    <td class="tdl">35 Leucothea</td>
+    <td class="tdl">1855, April 19</td>
+    <td class="tdl">Luther</td>
+    <td class="tdl">Bilk</td>
+    <td class="tdc">4</td></tr>
+  <tr>
+    <td class="tdl">36 Atalante</td>
+    <td class="tdl">1855, Oct. 5</td>
+    <td class="tdl">Goldschmidt</td>
+    <td class="tdl">Paris</td>
+    <td class="tdc">3</td></tr>
+  <tr>
+    <td class="tdl">37 Fides</td>
+    <td class="tdl">1855, Oct. 5</td>
+    <td class="tdl">Luther</td>
+    <td class="tdl">Bilk</td>
+    <td class="tdc">5</td></tr>
+  <tr>
+    <td class="tdl">38 Leda</td>
+    <td class="tdl">1856, Jan. 12</td>
+    <td class="tdl">Chacornac</td>
+    <td class="tdl">Paris</td>
+    <td class="tdc">4</td></tr>
+  <tr>
+    <td class="tdl">39 Lætitia</td>
+    <td class="tdl">1856, Feb. 8</td>
+    <td class="tdl">Chacornac</td>
+    <td class="tdl">Paris</td>
+    <td class="tdc">5</td></tr>
+  <tr>
+    <td class="tdl">40 Harmonia</td>
+    <td class="tdl">1856, March 31</td>
+    <td class="tdl">Goldschmidt</td>
+    <td class="tdl">Paris</td>
+    <td class="tdc">4</td></tr>
+  <tr>
+    <td class="tdl">41 Daphne</td>
+    <td class="tdl">1856, May 22</td>
+    <td class="tdl">Goldschmidt</td>
+    <td class="tdl">Paris</td>
+    <td class="tdc">5</td></tr>
+  <tr>
+    <td class="tdl">42 Isis</td>
+    <td class="tdl">1856, May 23</td>
+    <td class="tdl">Pogson</td>
+    <td class="tdl">Oxford</td>
+    <td class="tdc">1</td></tr>
+  <tr>
+    <td class="tdl">43 Ariadne</td>
+    <td class="tdl">1857, April 15</td>
+    <td class="tdl">Pogson</td>
+    <td class="tdl">Oxford</td>
+    <td class="tdc">2</td></tr>
+  <tr>
+    <td class="tdl">44 Nysa</td>
+    <td class="tdl">1857, May 27</td>
+    <td class="tdl">Goldschmidt</td>
+    <td class="tdl">Paris</td>
+    <td class="tdc">6</td></tr>
+  <tr>
+    <td class="tdl">45 Eugenia</td>
+    <td class="tdl">1857, June 28</td>
+    <td class="tdl">Goldschmidt</td>
+    <td class="tdl">Paris</td>
+    <td class="tdc">7</td></tr>
+  <tr>
+    <td class="tdl">46 Hastia</td>
+    <td class="tdl">1857, August 16</td>
+    <td class="tdl">Pogson</td>
+    <td class="tdl">Oxford</td>
+    <td class="tdc">3</td></tr>
+  <tr>
+    <td class="tdl">47 Aglaia</td>
+    <td class="tdl">1857, Sept. 15</td>
+    <td class="tdl">Luther</td>
+    <td class="tdl">Bilk</td>
+    <td class="tdc">6</td></tr>
+  <tr>
+    <td class="tdl">48 Doris</td>
+    <td class="tdl">1857, Sept. 19</td>
+    <td class="tdl">Goldschmidt</td>
+    <td class="tdl">Paris</td>
+    <td class="tdc">8</td></tr>
+  <tr>
+    <td class="tdl">49 Pales</td>
+    <td class="tdl">1857, Sept. 19</td>
+    <td class="tdl">Goldschmidt</td>
+    <td class="tdl">Paris</td>
+    <td class="tdc">9</td></tr>
+  <tr>
+    <td class="tdl">50 Virginia</td>
+    <td class="tdl">1857, Oct. 4</td>
+    <td class="tdl">Furguson</td>
+    <td class="tdl">Washington</td>
+    <td class="tdc">2</td></tr>
+  <tr>
+    <td class="tdl">51 Nemausa</td>
+    <td class="tdl">1858, Jan. 22</td>
+    <td class="tdl">Laurent</td>
+    <td class="tdl">Nismes</td>
+    <td class="tdc">1</td></tr>
+  <tr>
+    <td class="tdl">52 Europa</td>
+    <td class="tdl">1858, Feb. 6</td>
+    <td class="tdl">Goldschmidt</td>
+    <td class="tdl">Paris</td>
+    <td class="tdc">10 </td></tr>
+  <tr>
+    <td class="tdl">53 Calypso</td>
+    <td class="tdl">1858, April 8</td>
+    <td class="tdl">Luther</td>
+    <td class="tdl">Bilk</td>
+    <td class="tdc">7</td></tr>
+  <tr>
+    <td class="tdl">54 Alexandra</td>
+    <td class="tdl">1858, Sept. 11</td>
+    <td class="tdl">Goldschmidt</td>
+    <td class="tdl">Paris</td>
+    <td class="tdc">11 </td></tr>
+  <tr>
+    <td class="tdl bb">55 (Not named)</td>
+    <td class="tdl bb">1858, Sept. 11</td>
+    <td class="tdl bb">Searle</td>
+    <td class="tdl bb">Albany</td>
+    <td class="tdc bb">1</td></tr>
+</table>
+
+<p><span class="pagenum"><a name="Page_240" id="Page_240">240</a></span></p>
+
+<h3>THE COMET OF DONATI.</h3>
+
+<p>While this sheet was passing through the press, the attention
+of astronomers, and of the public generally, was drawn to the
+fact of the above Comet passing (on Oct. 18) within nine millions
+of miles of the planet Venus, or less than 9/100ths of the
+earth’s distance from the Sun. “And (says Mr. Hind, the astronomer),
+it is obvious that if the comet had reached its least
+distance from the sun a few days earlier than it has done, the
+planet might have passed through it; and I am very far from
+thinking that close proximity to a comet of this description
+would be unattended with danger. The inhabitants of Venus
+will witness a cometary spectacle far superior to that which
+has recently attracted so much attention here, inasmuch as the
+tail will doubtless appear twice as long from that planet as
+from the earth, and the nucleus proportionally more brilliant.”</p>
+
+<p>This Comet was first discovered by Dr. G.&nbsp;B. Donati, astronomer
+at the Museum of Florence, on the evening of the 2d of
+June, in right ascension 141° 18′, and north declination 23° 47′,
+corresponding to a position near the star Leonis. Previous to
+this date we had no knowledge of its existence, and therefore
+it was not a predicted comet; neither is it the one last observed
+in 1556. At the date of discovery it was distant from
+the earth 228,000,000 of miles, and was an excessively faint object
+in the largest telescopes.</p>
+
+<p>The tail, from October 2 to 16, when the comet was most
+conspicuous, appears to have maintained an average length
+of at least 40,000,000 miles, subtending an angle varying from
+30° to 40°. The dark line or space down the centre, frequently
+remarked in other great comets, was a striking characteristic
+in that of Donati. The nucleus, though small, was
+intensely brilliant in powerful instruments, and for some time
+bore high magnifiers to much greater advantage than is usual
+with these objects. In several respects this comet resembled
+the famous ones of 1744, 1680, and 1811, particularly as regards
+the signs of violent agitation going on in the vicinity of
+the nucleus, such as the appearance of luminous jets, spiral
+offshoots, &amp;c., which rapidly emanated from the planetary point
+and as quickly lost themselves in the general nebulosity of the
+head.</p>
+
+<p>On the 5th Oct. the most casual observer had an opportunity
+of satisfying himself as to the accuracy of the mathematical
+theory of the motions of comets in the near approach of the
+nucleus of Donati’s to Arcturus, the principal star in the constellation
+Bootes. The circumstance of the appulse was very
+nearly as predicted by Mr. Hind.</p>
+
+<p>The comet, according to the investigations by M. Loewy,<span class="pagenum"><a name="Page_241" id="Page_241">241</a></span>
+of the Observatory of Vienna, arrived at its least distance from
+the sun a few minutes after eleven o’clock on the morning of
+the 30th of September; its longitude, as seen from the sun at
+this time, being 36° 13′, and its distance from him 55,000,000
+miles. The longer diameter of its orbit is 184 times that of
+the earth’s, or 35,100,000,000 miles; yet this is considerably
+less than 1/1000th of the distance of the nearest fixed star. As
+an illustration, let any one take a half-sheet of note-paper, and
+marking a circle with a sixpence in one corner of it, describe
+therein our solar system, drawing the orbits of the earth and
+the inferior planets as small as he can by the aid of a magnifying-glass.
+If the circumference of the sixpence stands for the
+orbit of Neptune, then an oval filling the page will fairly represent
+the orbit of Donati’s comet; and if the paper be laid upon
+the pavement under the west door of St. Paul’s Cathedral, London,
+the length of that edifice will inadequately represent the
+distance of the nearest fixed star. The time of revolution resulting
+from Mr. Loewy’s calculations is 2495 years, which is
+about 500 years less than that of the comet of 1811 during the
+period it was visible from the earth.</p>
+
+<p>That the comet should take more than 2000 years to travel
+round the above page of note-paper is explained by its great
+diminution of speed as it recedes from the sun. At its perihelion
+it travelled at the rate of 127,000 miles an hour, or more than
+twice as fast as the earth, whose motion is about 1000 miles a
+minute. At its aphelion, however, or its greatest distance from
+the sun, the comet is a very slow body, sailing at the rate of
+480 miles an hour, or only eight times the speed of a railway
+express. At this pace, were it to travel onward in a straight
+line, the lapse of a million of years would find it still travelling
+half way between our sun and the nearest fixed star.</p>
+
+<p>As this comet last visited us between 2000 and 2495 years
+since, we know that its appearance was at an interesting period
+of the world’s history. It might have terrified the Athenians
+into accepting the bloody code of Draco. It might have announced
+the destruction of Nineveh, or of Babylon, or the
+capture of Jerusalem by Nebuchadnezzar. It might have been
+seen by the expedition which sailed round Africa in the reign
+of Pharaoh Necho. It might have given interest to the foundation
+of the Pythian games. Within the probable range of its
+last visitation are comprehended the whole of the great events
+of the history of Greece; and among the spectators of the comet
+may have been the so-called sages of Greece and even the prophets
+of Holy Writ: Thales might have attempted to calculate
+its return, and Jeremiah might have tried to read its warning.&mdash;<i>Abridged
+from a Communication from Mr. Hind to the Times, and from a Leader
+in that Journal.</i></p>
+
+<p><span class="pagenum"><a name="Page_242" id="Page_242">242</a></span></p>
+
+<div class="chapter"></div>
+<div class="footnotes">
+<h2 class="p0 p1"><a name="FOOTNOTES" id="FOOTNOTES"></a>FOOTNOTES:</h2>
+
+<div class="footnote">
+
+<p class="fn1"><a name="Footnote_1" id="Footnote_1" href="#FNanchor_1" class="fnanchor">1</a> From a photograph, with figures, to show the relative size of the tube aperture.</p></div>
+
+<div class="footnote">
+
+<p class="fn1"><a name="Footnote_2" id="Footnote_2" href="#FNanchor_2" class="fnanchor">2</a> Weld’s <i>History of the Royal Society</i>, vol. ii. p. 188.</p></div>
+
+<div class="footnote">
+
+<p class="fn1"><a name="Footnote_3" id="Footnote_3" href="#FNanchor_3" class="fnanchor">3</a> Dr. Whewell (<i>Bridgewater Treatise</i>, p. 266) well observes, that Boyle and
+Pascal are to hydrostatics what Galileo is to mechanics, and Copernicus, Kepler,
+and Newton are to astronomy.</p></div>
+
+<div class="footnote">
+
+<p class="fn1"><a name="Footnote_4" id="Footnote_4" href="#FNanchor_4" class="fnanchor">4</a> The Rev. Mr. Turnor recollects that Mr. Jones, the tutor, mentioned, in one
+of his lectures on optics, that the reflecting telescope belonging to Newton was
+then lodged in the observatory over the gateway; and Mr. Turnor thinks that
+he once saw it, with a finder affixed to it.</p></div>
+
+<div class="footnote">
+
+<p class="fn1"><a name="Footnote_5" id="Footnote_5" href="#FNanchor_5" class="fnanchor">5</a> The story of the dog “Diamond” having caused the burning of certain
+papers is laid in London, and in Newton’s later years. In the notes to Maude’s
+<i>Wenleysdale</i>, a person then living (1780) relates, that Sir Isaac being called out
+of his study to a contiguous room, a little dog, called Diamond, the constant
+but incurious attendant of his master’s researches, happened to be left among
+the papers, and by a fatality not to be retrieved, as it was in the latter part of
+Sir Isaac’s days, threw down a lighted candle, which consumed the almost
+finished labour of some years. Sir Isaac returning too late but to behold the
+dreadful wreck, rebuked the author of it with an exclamation (<i>ad sidera palmas</i>),
+“O Diamond! Diamond! thou little knowest the mischief done!” without adding
+a single stripe. M. Biot gives this fiction as a true story, which happened
+some years after the publication of the <i>Principia</i>; and he characterises the accident
+as having deprived the sciences forever of the fruit of so much of Newton’s
+labours.&mdash;Brewster’s <i>Life</i>, vol. ii. p. 139, note. Dr. Newton remarks, that Sir
+Isaac never had any communion with dogs or cats; and Sir David Brewster
+adds, that the view which M. Biot has taken of the idle story of the dog Diamond,
+charged with fire-raising among Newton’s manuscripts, and of the influence
+of this accident upon the mind of their author, is utterly incomprehensible.
+The fiction, however, was turned to account in giving colour to M. Biot’s misrepresentation.</p></div>
+
+<div class="footnote">
+
+<p class="fn1"><a name="Footnote_6" id="Footnote_6" href="#FNanchor_6" class="fnanchor">6</a> Bohn’s edition.</p></div>
+
+<div class="footnote">
+
+<p class="fn1"><a name="Footnote_7" id="Footnote_7" href="#FNanchor_7" class="fnanchor">7</a> When at Pisa, many years since, Captain Basil Hall investigated the
+origin and divergence of the tower from the perpendicular, and established
+completely to his own satisfaction that it had been built from top to bottom
+originally just as it now stands. His reasons for thinking so were, that the line
+of the tower, on that side towards which it leans, has not the same curvature as
+the line on the opposite, or what may be called the upper side. If the tower
+had been built upright, and then been made to incline over, the line of the wall
+on that side towards which the inclination was given would be more or less
+concave in that direction, owing to the nodding or “swagging over” of the top,
+by the simple action of gravity acting on a very tall mass of masonry, which is
+more or less elastic when placed in a sloping position. But the contrary is the
+fact; for the line of wall on the side towards which the tower leans is decidedly
+more convex than the opposite side. Captain Hall had therefore no doubt
+whatever that the architect, in rearing his successive courses of stones, gained
+or stole a little at each layer, so as to render his work less and less overhanging
+as he went up; and thus, without betraying what he was about, really gained
+stability.&mdash;See <i>Patchwork</i>.</p></div>
+
+<div class="footnote">
+
+<p class="fn1"><a name="Footnote_8" id="Footnote_8" href="#FNanchor_8" class="fnanchor">8</a> Lord Bacon proposed that, in order to determine whether the gravity of the
+earth arises from the gravity of its parts, a clock-pendulum should be swung in
+a mine, as was recently done at Harton colliery by the Astronomer-Royal.
+</p>
+<p>
+When, in 1812, Ampère noted the phenomena of the pendulum, and showed
+that its movement was produced only when the eye of the observer was fixed
+on the instrument, and endeavoured to prove thereby that the motion was due to
+a play of the muscles, some members of the French Academy objected to the
+consideration of a subject connected to such an extent with superstition.</p></div>
+
+<div class="footnote">
+
+<p class="fn1"><a name="Footnote_9" id="Footnote_9" href="#FNanchor_9" class="fnanchor">9</a> This curious fact was first recorded by Pepys, in his <i>Diary</i>, under the date
+31st of July 1665.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_10" id="Footnote_10" href="#FNanchor_10" class="fnanchor">10</a> The result of these experiments for ascertaining the variation of the gravity
+at great depths, has proved beyond doubt that the attraction of gravitation
+is increased at the depth of 1250 feet by 1/19000 part.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_11" id="Footnote_11" href="#FNanchor_11" class="fnanchor">11</a> See the account of Mr. Baily’s researches (with two illustrations) in <i>Things
+not generally Known</i>, p. vii., and “Weight of the Earth,” p. 16.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_12" id="Footnote_12" href="#FNanchor_12" class="fnanchor">12</a> Fizeau gives his result in leagues, reckoning twenty-five to the equatorial
+degree. He estimates the velocity of light at 70,000 such leagues, or about
+210,000 miles in the second.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_13" id="Footnote_13" href="#FNanchor_13" class="fnanchor">13</a> See <i>Things not generally Known</i>, p. 88.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_14" id="Footnote_14" href="#FNanchor_14" class="fnanchor">14</a> Some time before the first announcement of the discovery of sun-painting,
+the following extract from Sir John Herschel’s <i>Treatise on Light</i>, in the <i>Encyclopædia
+Metropolitana</i>, appeared in a popular work entitled <i>Parlour Magic</i>: “Strain
+a piece of paper or linen upon a wooden frame, and sponge it over with a solution
+of nitrate of silver in water; place it behind a painting upon glass, or a stained
+window-pane, and the light, traversing the painting or figures, will produce a
+copy of it upon the prepared paper or linen; those parts in which the rays were
+least intercepted being the shadows of the picture.”</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_15" id="Footnote_15" href="#FNanchor_15" class="fnanchor">15</a> In his book on Colours, Mr. Doyle informs us that divers, if not all, essential
+oils, as also spirits of wine, when shaken, “have a good store of bubbles,
+which appear adorned with various and lively colours.” He mentions also that
+bubbles of soap and turpentine exhibit the same colours, which “vary according
+to the incidence of the sight and the position of the eye;” and he had seen a
+glass-blower blow bubbles of glass which burst, and displayed “the varying
+colours of the rainbow, which were exceedingly vivid.”</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_16" id="Footnote_16" href="#FNanchor_16" class="fnanchor">16</a> The original idea is even attributed to Copernicus. M. Blundevile, in his
+<i>Treatise on Cosmography</i>, 1594, has the following passage, perhaps the most distinct
+recognition of authority in our language: “How prooue (prove) you that
+there is but one world? By the authoritie of Aristotle, who saieth that if there
+were any other world out of this, then the earth of that world would mooue
+(move) towards the centre of this world,” &amp;c.
+</p>
+<p>
+Sir Isaac Newton, in a conversation with Conduitt, said he took “all the
+planets to be composed of the same matter with the earth, viz. earth, water, and
+stone, but variously concocted.”</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_17" id="Footnote_17" href="#FNanchor_17" class="fnanchor">17</a> Sir William Herschel ascertained that our solar system is advancing towards
+the constellation Hercules, or more accurately to a point in space whose
+right ascension is 245° 52′ 30″, and north polar distance 40° 22′; and that the
+quantity of this motion is such, that to an astronomer placed in Sirius, our sun
+would appear to describe an arc of little more than <i>a second</i> every year.&mdash;<i>North-British
+Review</i>, No. 3.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_18" id="Footnote_18" href="#FNanchor_18" class="fnanchor">18</a> See M. Arago’s researches upon this interesting subject, in <i>Things not generally
+Known</i>, p. 4.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_19" id="Footnote_19" href="#FNanchor_19" class="fnanchor">19</a> This eloquent advocacy of the doctrine of “More Worlds than One” (referred
+to at p. 51) is from the author’s valuable <i>Outlines of Astronomy</i>.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_20" id="Footnote_20" href="#FNanchor_20" class="fnanchor">20</a> Professor Challis, of the Cambridge Observatory, directing the Northumberland
+telescope of that institution to the place assigned by Mr. Adams’s calculations
+and its vicinity on the 4th and 12th of August 1846, saw the planet on
+both those days, and noted its place (among those of other stars) for re-observation.
+He, however, postponed the <i>comparison</i> of the places observed, and not
+possessing Dr. Bremiker’s chart (which would at once have indicated the presence
+of an unmapped star), remained in ignorance of the planet’s existence as a
+visible object till the announcement of such by Dr. Galle.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_21" id="Footnote_21" href="#FNanchor_21" class="fnanchor">21</a> For several interesting details of Comets, see “Destruction of the World
+by a Comet,” in <i>Popular Errors Explained and Illustrated</i>, new edit. pp. 165&ndash;168.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_22" id="Footnote_22" href="#FNanchor_22" class="fnanchor">22</a> The letters of Sir Isaac Newton to Dr. Bentley, containing suggestions for
+the Boyle Lectures, possess a peculiar interest in the present day. “They show”
+(says Sir David Brewster) “that the <i>nebular hypothesis</i>, the dull and dangerous
+heresy of the age, is incompatible with the established laws of the material universe,
+and that an omnipotent arm was required to give the planets their positions
+and motions in space, and a presiding intelligence to assign to them the
+different functions they had to perform.”&mdash;<i>Life of Newton</i>, vol. ii.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_23" id="Footnote_23" href="#FNanchor_23" class="fnanchor">23</a> The constitution of the nebulæ in the constellation of Orion has been resolved
+by this instrument; and by its aid the stars of which it is composed
+burst upon the sight of man for the first time.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_24" id="Footnote_24" href="#FNanchor_24" class="fnanchor">24</a> Several specimens of Meteoric Iron are to be seen in the Mineralogical
+Collection in the British Museum.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_25" id="Footnote_25" href="#FNanchor_25" class="fnanchor">25</a> <i>Life of Sir Isaac Newton</i>, vol. i. p. 62.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_26" id="Footnote_26" href="#FNanchor_26" class="fnanchor">26</a> <i>Description of the Monster Telescope</i>, by Thomas Woods, M.D. 4th edit. 1851.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_27" id="Footnote_27" href="#FNanchor_27" class="fnanchor">27</a> This instrument also discovered a multitude of new objects in the moon;
+as a mountainous tract near Ptolemy, every ridge of which is dotted with extremely
+minute craters, and two black parallel stripes in the bottom of Aristarchus.
+Dr. Robinson, in his address to the British Association in 1843, stated that
+in this telescope a building the size of the Court-house at Cork would be easily
+visible on the lunar surface.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_28" id="Footnote_28" href="#FNanchor_28" class="fnanchor">28</a> Mr. Hopkins supports his Glacial Theory by regarding the <i>Waves of Translation</i>,
+investigated by Mr. Scott Russell, as furnishing a sufficient moving power
+for the transportation of large rounded boulders, and the formation of drifted
+gravel. When these waves of translation are produced by the sudden elevation
+of the surface of the sea, the whole mass of water from the surface to the bottom
+of the ocean moves onward, and becomes a mechanical agent of enormous power.
+Following up this view, Mr. Hopkins has shown that “elevations of continental
+masses of only 50 feet each, and from beneath an ocean having a depth of between
+300 and 400 feet, would cause the most powerful divergent waves, which
+could transport large boulders to great distances.”</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_29" id="Footnote_29" href="#FNanchor_29" class="fnanchor">29</a> It is scarcely too much to say, that from the collection of specimens of
+building-stones made upon this occasion, and first deposited in a house in Craig’s
+Court, Charing Cross, originated, upon the suggestion of Sir Henry Delabeche,
+the magnificent Museum of Practical Geology in Jermyn Street; one of the most
+eminently practical institutions of this scientific age.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_30" id="Footnote_30" href="#FNanchor_30" class="fnanchor">30</a> Mr. R. Mallet, F.R.S., and his son Dr. Mallet, have constructed a seismographic
+map of the world, with seismic bands in their position and relative
+intensity; and small black discs to denote volcanoes, femaroles, and soltataras,
+and shades indicating the areas of subsidence.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_31" id="Footnote_31" href="#FNanchor_31" class="fnanchor">31</a> It has been computed that the shock of this earthquake pervaded an area
+of 700,000 miles, or the twelfth part of the circumference of the globe. This
+dreadful shock lasted only five minutes; and nearly the whole of the population
+being within the churches (on the feast of All Saints), no less than 30,000 persons
+perished by the fall of these edifices.&mdash;See <i>Daubeny on Volcanoes</i>; <i>Translator’s
+note, Humboldt’s Cosmos</i>.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_32" id="Footnote_32" href="#FNanchor_32" class="fnanchor">32</a> Mr. Murray mentions, on the authority of the Rev. Dr. Robinson, of the
+Observatory at Armagh, that a rough diamond with a red tint, and valued by
+Mr. Rundell at twenty guineas, was found in Ireland, many years since, in the
+bed of a brook flowing through the county of Fermanagh.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_33" id="Footnote_33" href="#FNanchor_33" class="fnanchor">33</a> The use of malachite in ornamental work is very extensive in Russia.
+Thus, to the Great Exhibition of 1851 were sent a pair of folding-doors veneered
+with malachite, 13 feet high, valued at 6000<i>l.</i>; malachite cases and pedestals from
+1500<i>l.</i> to 3000<i>l.</i> a-piece, malachite tables 400<i>l.</i>, and chairs 150<i>l.</i> each.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_34" id="Footnote_34" href="#FNanchor_34" class="fnanchor">34</a> Longfellow has written some pleasing lines on “The Fiftieth Birthday of
+M. Agassiz. May 28, 1857,” appended to “The Courtship of Miles Standish,”
+1858.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_35" id="Footnote_35" href="#FNanchor_35" class="fnanchor">35</a> The <i>sloth</i> only deserves its name when it is obliged to attempt to proceed
+along the ground; when it has any thing which it can lay hold of it is agile
+enough.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_36" id="Footnote_36" href="#FNanchor_36" class="fnanchor">36</a> Dr. A. Thomson has communicated to <i>Jameson’s Journal</i>, No. 112, a Description
+of the Caves in the North Island, with some general observations on
+this genus of birds. He concludes them to have been indolent, dull, and stupid;
+to have lived chiefly on vegetable food in mountain fastnesses and secluded
+caverns.
+</p>
+<p>
+In the picture-gallery at Drayton Manor, the seat of Sir Robert Peel, hangs a
+portrait of Professor Owen, and in his hand is depicted the tibia of a Moa.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_37" id="Footnote_37" href="#FNanchor_37" class="fnanchor">37</a> According to the law of correlation, so much insisted on by Cuvier, a superior
+character implies the existence of its inferiors, and that too in definite proportions
+and constant connections; so that we need only the assurance of one
+character, to be able to reconstruct the whole animal. The triumph of this system
+is seen in the reconstruction of extinct animals, as in the above case of the Dinornis,
+accomplished by Professor Owen.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_38" id="Footnote_38" href="#FNanchor_38" class="fnanchor">38</a> Not only at London, but at Paris, Vienna, Berlin, Turin. St. Petersburg,
+and almost every other capital in Europe; at Liege, Caen, Montpellier, Toulouse,
+and several other large towns,&mdash;wherever, in fact, there are not great local obstacles,&mdash;the
+tendency of the wealthier inhabitants to group themselves to the west
+is as strongly marked as in the British metropolis. At Pompeii, and other ancient
+towns, the same thing maybe noticed; and where the local configuration of
+the town necessitates an increase in a different direction, the moment the obstacle
+ceases houses spread towards the west.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_39" id="Footnote_39" href="#FNanchor_39" class="fnanchor">39</a> By far the most complete set of experiments on the Radiation of Heat from
+the Earth’s Surface at Night which have been published since Dr. Wells’s Memoir
+<i>On Dew</i>, are those of Mr. Glaisher, F.R.S., <i>Philos. Trans.</i> for 1847.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_40" id="Footnote_40" href="#FNanchor_40" class="fnanchor">40</a> The author is largely indebted for the illustrations in this new field of
+research to Lieutenant Maury’s valuable work, <i>The Physical Geography of the Sea</i>.
+Sixth edition. Harper, New York; Low, Son, and Co., London.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_41" id="Footnote_41" href="#FNanchor_41" class="fnanchor">41</a> It is the chloride of magnesia which gives that damp sticky feeling to the
+clothes of sailors that are washed or wetted with salt water.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_42" id="Footnote_42" href="#FNanchor_42" class="fnanchor">42</a> This fraction rests on the assumption that the dilatation of the substances
+of which the earth is composed is equal to that of glass, that is to say, 1/18000 for
+1°. Regarding this hypothesis, see Arago, in the <i>Annuaire</i> for 1834, pp. 177&ndash;190.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_43" id="Footnote_43" href="#FNanchor_43" class="fnanchor">43</a> Electricity, traversing excessively rarefied air or vapours, gives out light,
+and doubtless also heat. May not a continual current of electric matter be constantly
+circulating in the sun’s immediate neighbourhood, or traversing the
+planetary spaces, and exerting in the upper regions of its atmosphere those
+phenomena of which, on however diminutive a scale, we have yet an unequivocal
+manifestation in our Aurora Borealis?</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_44" id="Footnote_44" href="#FNanchor_44" class="fnanchor">44</a> Could we by mechanical pressure force water into a solid state, an immense
+quantity of heat would be set free.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_45" id="Footnote_45" href="#FNanchor_45" class="fnanchor">45</a> See Mr. Hunt’s popular work, <i>The Poetry of Science; or, Studies of Physical
+Phenomena of Nature</i>. Third edition, revised and enlarged. Bohn, 1854.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_46" id="Footnote_46" href="#FNanchor_46" class="fnanchor">46</a> Canton was the first who in England verified Dr. Franklin’s idea of the
+similarity of lightning and the electric fluid, July 1752.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_47" id="Footnote_47" href="#FNanchor_47" class="fnanchor">47</a> This is mentioned in <i>Procli Diadochi Paraphrasis Ptolem.</i>, 1635. (Delambre,
+<i>Hist. de l’Astronomie ancienne</i>.)</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_48" id="Footnote_48" href="#FNanchor_48" class="fnanchor">48</a> The first Variation-Compass was constructed, before 1525, by an ingenious
+apothecary of Seville, Felisse Guillen. So earnest were the endeavours to learn
+more exactly the direction of the curves of magnetic declination, that in 1585
+Juan Jayme sailed with Francisco Gali from Manilla to Acapulco, for the sole
+purpose of trying in the Pacific a declination instrument which he had invented.&mdash;<i>Humboldt.</i></p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_49" id="Footnote_49" href="#FNanchor_49" class="fnanchor">49</a> Gilbert was surgeon to Queen Elizabeth and James I., and died in 1603.
+Whewell justly assigns him an important place among the “practical reformers
+of the physical sciences.” He adopted the Copernican doctrine, which Lord Bacon’s
+inferior aptitude for physical research led him to reject.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_50" id="Footnote_50" href="#FNanchor_50" class="fnanchor">50</a> This illustration, it will be seen, does not literally correspond with the
+details which precede it.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_51" id="Footnote_51" href="#FNanchor_51" class="fnanchor">51</a> Mr. Crosse gave to the meeting a general invitation to Fyne Court; one of
+the first to accept which was Sir Richard Phillips, who, on his return to Brighton,
+described in a very attractive manner, at the Sussex Institution, Mr. Crosse’s
+experiments and apparatus; a report of which being communicated to the
+<i>Brighton Herald</i>, was quoted in the <i>Literary Gazette</i>, and thence copied generally
+into the newspapers of the day.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_52" id="Footnote_52" href="#FNanchor_52" class="fnanchor">52</a> These experiments were performed at the expense of the Royal Society, and
+cost 10<i>l.</i> 5<i>s.</i> 6<i>d.</i> In the Paper detailing the experiments, printed in the 45th
+volume of the <i>Philosophical Transactions</i>, occurs the first mention of Dr. Franklin’s
+name, and of his theory of positive and negative electricity.&mdash;<i>Weld’s Hist. Royal
+Soc.</i> vol. i. p. 467.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_53" id="Footnote_53" href="#FNanchor_53" class="fnanchor">53</a> In this year Andrew Crosse said: “I prophesy that by means of the electric
+agency we shall be enabled to communicate our thoughts instantaneously with
+the uttermost parts of the earth.”</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_54" id="Footnote_54" href="#FNanchor_54" class="fnanchor">54</a> To which paper the writer is indebted for many of these details.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_55" id="Footnote_55" href="#FNanchor_55" class="fnanchor">55</a> These illustrations have been in the main selected and abridged from papers
+in the <i>Companion to the Almanac</i>, 1858, and the <i>Penny Cyclopædia</i>, 2d supp.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_56" id="Footnote_56" href="#FNanchor_56" class="fnanchor">56</a> Newton was, however, much pestered with inquirers; and a Correspondent
+of the <i>Gentleman’s Magazine</i>, in 1784, relates that he once had a transient view of
+a Ms. in Pope’s handwriting, in which he read a verified anecdote relating to the
+above period. Sir Isaac being often interrupted by ignorant pretenders to the
+discovery of the longitude, ordered his porter to inquire of every stranger who
+desired admission whether he came about the longitude, and to exclude such as
+answered in the affirmative. Two lines in Pope’s Ms., as the Correspondent recollects,
+ran thus:
+</p>
+
+<div class="poem-container">
+<div class="poem"><div class="stanza">
+<span class="iq">“‘Is it about the longitude you come?’<br /></span>
+<span class="i0">The porter asks: ‘Sir Isaac’s not at home.’”<br /></span>
+</div></div>
+</div>
+</div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_57" id="Footnote_57" href="#FNanchor_57" class="fnanchor">57</a> In trying the merits of Harrison’s chronometers, Dr. Maskelyne acquired
+that knowledge of the wants of nautical astronomy which afterwards led to the
+formation of the Nautical Almanac.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_58" id="Footnote_58" href="#FNanchor_58" class="fnanchor">58</a> A slight electric shock is given to a man at a certain portion of the skin;
+and he is directed the moment he feels the stroke to make a certain motion, as
+quickly as he possibly can, with the hands or with the teeth, by which the time-measuring
+current is interrupted.</p></div>
+
+<div class="footnote">
+
+<p class="fn2"><a name="Footnote_59" id="Footnote_59" href="#FNanchor_59" class="fnanchor">59</a> Through the calculations of M. Le Verrier.</p></div>
+</div>
+
+<div class="chapter"></div>
+<h2><a name="GENERAL_INDEX" id="GENERAL_INDEX"></a>GENERAL INDEX</h2>
+
+<div class="index">
+<ul class="index"><li class="ifrst">Abodes of the Blest, <a href="#Page_58">58</a>.</li>
+
+<li class="indx">Acarus of Crosse and Weeks, <a href="#Page_218">218</a>.</li>
+
+<li class="indx">Accuracy of Chinese Observers, <a href="#Page_159">159</a>.</li>
+
+<li class="indx">Adamant, What was it?, <a href="#Page_123">123</a>.</li>
+
+<li class="indx">Aeronautic Voyage, Remarkable, <a href="#Page_169">169</a>.</li>
+
+<li class="indx">Agassiz, Discoveries of, <a href="#Page_127">127</a>.</li>
+
+<li class="indx">Air, Weight of, <a href="#Page_14">14</a>.</li>
+
+<li class="indx">All the World in Motion, <a href="#Page_11">11</a>.</li>
+
+<li class="indx">Alluvial Land of Egypt, <a href="#Page_110">110</a>.</li>
+
+<li class="indx">Ancient World, Science of the, <a href="#Page_1">1</a>.</li>
+
+<li class="indx">Animals in Geological Times, <a href="#Page_128">128</a>.</li>
+
+<li class="indx">Anticipations of the Electric Telegraph, <a href="#Page_220">220&ndash;224</a>.</li>
+
+<li class="indx">Arago on Protection from Storms, <a href="#Page_159">159</a>.</li>
+
+<li class="indx">Arctic Climate, Phenomena of, <a href="#Page_162">162</a>.</li>
+
+<li class="indx">Arctic Explorations, Rae’s, <a href="#Page_162">162</a>.</li>
+
+<li class="indx">Arctic Regions, Scenery and Life of, <a href="#Page_180">180</a>.</li>
+
+<li class="indx">Arctic Temperature, <a href="#Page_161">161</a>.</li>
+
+<li class="indx">Armagh Observatory Level, Change of, <a href="#Page_144">144</a>.</li>
+
+<li class="indx">Artesian Fire-Springs, <a href="#Page_118">118</a>.</li>
+
+<li class="indx">Artesian Well of Grenelle, <a href="#Page_114">114</a>.</li>
+
+<li class="indx">Astronomer, Peasant, <a href="#Page_101">101</a>.</li>
+
+<li class="indx">Astronomer’s Dream verified, <a href="#Page_88">88</a>.</li>
+
+<li class="indx">Astronomers, Triad of Contemporary, <a href="#Page_100">100</a>.</li>
+
+<li class="indx">Astronomical Observations, Nicety of, <a href="#Page_102">102</a>.</li>
+
+<li class="indx">Astronomy and Dates on Monuments, <a href="#Page_55">55</a>.</li>
+
+<li class="indx">Astronomy and Geology, Identity of, <a href="#Page_104">104</a>.</li>
+
+<li class="indx">Astronomy, Great Truths of, <a href="#Page_54">54</a>.</li>
+
+<li class="indx">Atheism, Folly of, <a href="#Page_3">3</a>.</li>
+
+<li class="indx">Atlantic, Basin of the, <a href="#Page_171">171</a>.</li>
+
+<li class="indx">Atlantic, Gales of the, <a href="#Page_171">171</a>.</li>
+
+<li class="indx">Atlantic Telegraph, the, <a href="#Page_226">226&ndash;228</a>.</li>
+
+<li class="indx">Atmosphere, Colours of the, <a href="#Page_147">147</a>.</li>
+
+<li class="indx">Atmosphere compared to a Steam-engine, <a href="#Page_152">152</a>.</li>
+
+<li class="indx">Atmosphere, Height of, <a href="#Page_147">147</a>.</li>
+
+<li class="indx">Atmosphere, the, <a href="#Page_146">146</a>.</li>
+
+<li class="indx">Atmosphere, the purest, <a href="#Page_150">150</a>.</li>
+
+<li class="indx">Atmosphere, Universality of the, <a href="#Page_147">147</a>.</li>
+
+<li class="indx">Atmosphere weighed by Pascal, <a href="#Page_148">148</a>.</li>
+
+<li class="indx">Atoms of Elementary Bodies, <a href="#Page_13">13</a>.</li>
+
+<li class="indx">Atoms, the World of, <a href="#Page_13">13</a>.</li>
+
+<li class="indx">Aurora Borealis, Halley’s hypothesis of, <a href="#Page_198">198</a>.</li>
+
+<li class="indx">Aurora Borealis, Splendour of the, <a href="#Page_165">165</a>.</li>
+
+<li class="indx">Australian Cavern, Inmates of, <a href="#Page_137">137</a>.</li>
+
+<li class="indx">Australian Pouch-Lion, <a href="#Page_137">137</a>.</li>
+
+<li class="indx">Axis of Rotation, the, <a href="#Page_11">11</a>.</li>
+
+<li class="ifrst">Barometer, Gigantic, <a href="#Page_151">151</a>.</li>
+
+<li class="indx">Barometric Measurement, <a href="#Page_151">151</a>.</li>
+
+<li class="indx">Batteries, Minute and Vast, <a href="#Page_204">204</a>.</li>
+
+<li class="indx">Birds, Gigantic, of New Zealand, Extinct, <a href="#Page_139">139</a>.</li>
+
+<li class="indx">“Black Waters, the,” <a href="#Page_182">182</a>.</li>
+
+<li class="indx">Bodies, Bright, the Smallest, <a href="#Page_31">31</a>.</li>
+
+<li class="indx">Bodies, Compression of, <a href="#Page_12">12</a>.</li>
+
+<li class="indx">Bodies, Fall of, <a href="#Page_16">16</a>.</li>
+
+<li class="indx">Bottles and Currents at Sea, <a href="#Page_172">172</a>.</li>
+
+<li class="indx">Boulders, How transported to Great Heights, <a href="#Page_105">105</a>.</li>
+
+<li class="indx">Boyle on Colours, <a href="#Page_49">49</a>.</li>
+
+<li class="indx">Boyle, Researches of, <a href="#Page_6">6</a>.</li>
+
+<li class="indx">Brain, Impressions transmitted to, <a href="#Page_235">235</a>.</li>
+
+<li class="indx">Buckland, Dr., his Geological Labours, <a href="#Page_127">127</a>.</li>
+
+<li class="indx">Building-Stone, Wear of, <a href="#Page_108">108</a>.</li>
+
+<li class="indx">Burnet’s Theory of the Earth, <a href="#Page_125">125</a>.</li>
+
+<li class="indx">Bust, Magic, <a href="#Page_36">36</a>.</li>
+
+<li class="ifrst">Candle-flame, Nature of, <a href="#Page_237">237</a>.</li>
+
+<li class="indx">Canton’s Artificial Magnets, <a href="#Page_196">196</a>.</li>
+
+<li class="indx">Carnivora of Britain, Extinct, <a href="#Page_132">132</a>.</li>
+
+<li class="indx">Carnivores, Monster, of France, <a href="#Page_138">138</a>.</li>
+
+<li class="indx">Cataract, Great, in India, <a href="#Page_183">183</a>.<span class="pagenum"><a name="Page_243" id="Page_243">243</a></span></li>
+
+<li class="indx">Cat, Can it see in the Dark?, <a href="#Page_51">51</a>.</li>
+
+<li class="indx">Caves of New Zealand and its Gigantic Birds, <a href="#Page_140">140</a>.</li>
+
+<li class="indx">Cave Tiger or Lion of Britain, <a href="#Page_133">133</a>.</li>
+
+<li class="indx">Central Heat, Theory of, <a href="#Page_116">116</a>.</li>
+
+<li class="indx">Chabert, “the Fire King,” <a href="#Page_192">192</a>.</li>
+
+<li class="indx">Chalk Formation, the, <a href="#Page_108">108</a>.</li>
+
+<li class="indx">Changes on the Earth’s Surface, <a href="#Page_142">142</a>.</li>
+
+<li class="indx">Chantrey, Heat-Experiments by, <a href="#Page_192">192</a>.</li>
+
+<li class="indx">Children’s powerful Battery, <a href="#Page_204">204</a>.</li>
+
+<li class="indx">Chinese, the, and the Magnetic Needle, <a href="#Page_194">194</a>.</li>
+
+<li class="indx">Chronometers, Marine, How rated at Greenwich Observatory, <a href="#Page_229">229</a>.</li>
+
+<li class="indx">Climate, finest in the World, <a href="#Page_149">149</a>.</li>
+
+<li class="indx">Climate, Variations of, <a href="#Page_148">148</a>.</li>
+
+<li class="indx">Climates, Average, <a href="#Page_149">149</a>.</li>
+
+<li class="indx">Clock, How to make Electric, <a href="#Page_212">212</a>.</li>
+
+<li class="indx">Cloud-ring, the Equatorial, <a href="#Page_156">156</a>.</li>
+
+<li class="indx">Clouds, Fertilisation of, <a href="#Page_151">151</a>.</li>
+
+<li class="indx">Coal, Torbane-Hill, <a href="#Page_123">123</a>.</li>
+
+<li class="indx">Coal, What is it?, <a href="#Page_123">123</a>.</li>
+
+<li class="indx">Cold in Hudson’s Bay, <a href="#Page_160">160</a>.</li>
+
+<li class="indx">Colour of a Body, and its Magnetic Properties, <a href="#Page_197">197</a>.</li>
+
+<li class="indx">Colours and Tints, Chevreul on, <a href="#Page_37">37</a>.</li>
+
+<li class="indx">Colours most frequently hit in Battle, <a href="#Page_36">36</a>.</li>
+
+<li class="indx">Comet, the, of Donati, <a href="#Page_240">240</a>, <a href="#Page_241">241</a>.</li>
+
+<li class="indx">Comet, Great, of 1843, <a href="#Page_84">84</a>.</li>
+
+<li class="indx">Comets, Magnitude of, <a href="#Page_84">84</a>.</li>
+
+<li class="indx">Comets visible in Sunshine, <a href="#Page_84">84</a>.</li>
+
+<li class="indx">Computation, Power of, <a href="#Page_10">10</a>.</li>
+
+<li class="indx">Coney of Scripture, <a href="#Page_137">137</a>.</li>
+
+<li class="indx">Conic Sections, <a href="#Page_10">10</a>.</li>
+
+<li class="indx">Continent Outlines not fixed, <a href="#Page_145">145</a>.</li>
+
+<li class="indx">Corpse, How soon it decays, <a href="#Page_237">237</a>.</li>
+
+<li class="indx">“Cosmos, Science of the,” <a href="#Page_10">10</a>.</li>
+
+<li class="indx">Crosse, Andrew, his Artificial Crystals and Minerals, <a href="#Page_216">216&ndash;219</a>.</li>
+
+<li class="indx">Crosse Mite, the, <a href="#Page_218">218</a>.</li>
+
+<li class="indx">Crystallisation, Reproductive, <a href="#Page_26">26</a>.</li>
+
+<li class="indx">Crystallisation, Theory of, <a href="#Page_24">24</a>.</li>
+
+<li class="indx">Crystallisation, Visible, <a href="#Page_25">25</a>.</li>
+
+<li class="indx">Crystals, Immense, <a href="#Page_24">24</a>.</li>
+
+<li class="indx">“Crystal Vault of Heaven,” <a href="#Page_55">55</a>.</li>
+
+<li class="ifrst">Davy, Sir Humphry, obtains Heat from Ice, <a href="#Page_190">190</a>.</li>
+
+<li class="indx">Davy’s great Battery at the Royal Institution, <a href="#Page_204">204</a>.</li>
+
+<li class="indx">Day, Length of, and Heat of the Earth, <a href="#Page_186">186</a>.</li>
+
+<li class="indx">Day’s Length at the Poles, <a href="#Page_65">65</a>.</li>
+
+<li class="indx">Declination of the Needle, <a href="#Page_197">197</a>.</li>
+
+<li class="indx">Descartes’ Labours in Physics, <a href="#Page_9">9</a>.</li>
+
+<li class="indx">Desert, Intense Heat and Cold of the, <a href="#Page_163">163</a>.</li>
+
+<li class="indx">Dew-drop, Beauty of the, <a href="#Page_157">157</a>.</li>
+
+<li class="indx">Dew-fall in one year, <a href="#Page_157">157</a>.</li>
+
+<li class="indx">Dew graduated to supply Vegetation, <a href="#Page_157">157</a>.</li>
+
+<li class="indx">Diamond, Geological Age of, <a href="#Page_122">122</a>.</li>
+
+<li class="indx">Diamond Lenses for Microscopes, <a href="#Page_40">40</a>.</li>
+
+<li class="indx">“Diamond,” Newton’s Dog, <a href="#Page_8">8</a>.</li>
+
+<li class="indx">Dinornis elephantopus, the, <a href="#Page_139">139</a>, <a href="#Page_140">140</a>.</li>
+
+<li class="indx">Dinotherium, or Terrible Beast, the, <a href="#Page_136">136</a>.</li>
+
+<li class="indx">Diorama, Illusion of the, <a href="#Page_37">37</a>.</li>
+
+<li class="ifrst">Earth and Man compared, <a href="#Page_22">22</a>.</li>
+
+<li class="indx">Earth, Figure of the, <a href="#Page_21">21</a>.</li>
+
+<li class="indx">Earth, Mass and Density of, <a href="#Page_21">21</a>.</li>
+
+<li class="indx">Earth’s Annual Motion, <a href="#Page_12">12</a>.</li>
+
+<li class="indx">Earth’s Magnitude, to ascertain, <a href="#Page_21">21</a>.</li>
+
+<li class="indx">Earth’s Surface, Mean Temperature of, <a href="#Page_23">23</a>.</li>
+
+<li class="indx">Earth’s Temperature, Interior, <a href="#Page_116">116</a>.</li>
+
+<li class="indx">Earth’s Temperature Stationary, <a href="#Page_23">23</a>.</li>
+
+<li class="indx">Earth, the, a Magnet, <a href="#Page_197">197</a>.</li>
+
+<li class="indx">Earthquake, the Great Lisbon, <a href="#Page_121">121</a>.</li>
+
+<li class="indx">Earthquakes and the Moon, <a href="#Page_121">121</a>.</li>
+
+<li class="indx">Earthquakes, Rumblings of, <a href="#Page_120">120</a>.</li>
+
+<li class="indx">Earthquake-Shock, How to measure, <a href="#Page_120">120</a>.</li>
+
+<li class="indx">Earth-Waves, <a href="#Page_119">119</a>.</li>
+
+<li class="indx">Eclipses, Cause of, <a href="#Page_74">74</a>.</li>
+
+<li class="indx">Egypt, Alluvial Land of, <a href="#Page_110">110</a>.</li>
+
+<li class="indx">Electric Girdle for the Earth, <a href="#Page_224">224</a>.</li>
+
+<li class="indx">Electric Incandescence of Charcoal Points, <a href="#Page_204">204</a>.</li>
+
+<li class="indx">Electric Knowledge, Germs of, <a href="#Page_207">207</a>.</li>
+
+<li class="indx">Electric Light, Velocity of, <a href="#Page_209">209</a>.</li>
+
+<li class="indx">Electric Messages, Time lost in, <a href="#Page_225">225</a>.</li>
+
+<li class="indx">Electric Paper, <a href="#Page_209">209</a>.</li>
+
+<li class="indx">Electric Spark, Duration of, <a href="#Page_209">209</a>.</li>
+
+<li class="indx">Electric Telegraph, Anticipations of the, <a href="#Page_220">220&ndash;224</a>.</li>
+
+<li class="indx">Electric Telegraph, Consumption of, <a href="#Page_224">224</a>.</li>
+
+<li class="indx">Electric Telegraph in Astronomy and Longitude, <a href="#Page_225">225</a>.<span class="pagenum"><a name="Page_244" id="Page_244">244</a></span></li>
+
+<li class="indx">Electric Telegraph and Lightning, <a href="#Page_226">226</a>.</li>
+
+<li class="indx">Electric and Magnetic Attraction, Identity of, <a href="#Page_210">210</a>.</li>
+
+<li class="indx">Electrical Kite, Franklin’s, <a href="#Page_213">213</a>.</li>
+
+<li class="indx">Electricity and Temperature, <a href="#Page_208">208</a>.</li>
+
+<li class="indx">Electricity in Brewing, <a href="#Page_209">209</a>.</li>
+
+<li class="indx">Electricity, Vast Arrangement of, <a href="#Page_208">208</a>.</li>
+
+<li class="indx">Electricity, Water decomposed by, <a href="#Page_208">208</a>.</li>
+
+<li class="indx">Electricities, the Two, <a href="#Page_214">214</a>.</li>
+
+<li class="indx">Electro-magnetic Clock, Wheatstone’s, <a href="#Page_211">211</a>.</li>
+
+<li class="indx">Electro-magnetic Engine, Theory of, <a href="#Page_210">210</a>.</li>
+
+<li class="indx">Electro-magnets, Horse-shoe, <a href="#Page_199">199</a>.</li>
+
+<li class="indx">Electro-telegraphic Message to the Stars, <a href="#Page_226">226</a>.</li>
+
+<li class="indx">Elephant and Tortoise of India, <a href="#Page_135">135</a>.</li>
+
+<li class="indx">End of our System, <a href="#Page_92">92</a>.</li>
+
+<li class="indx">England in the Eocene Period, <a href="#Page_129">129</a>.</li>
+
+<li class="indx">English Channel, Probable Origin of, <a href="#Page_105">105</a>.</li>
+
+<li class="indx">Eocene Period, the, <a href="#Page_129">129</a>.</li>
+
+<li class="indx">Equatorial Cloud-ring, <a href="#Page_156">156</a>.</li>
+
+<li class="indx">“Equatorial Doldrums,” <a href="#Page_156">156</a>.</li>
+
+<li class="indx">Error upon Error, <a href="#Page_185">185</a>.</li>
+
+<li class="indx">Exhilaration in ascending Mountains, <a href="#Page_163">163</a>.</li>
+
+<li class="indx">Eye and Brain seen through a Microscope, <a href="#Page_41">41</a>.</li>
+
+<li class="indx">Eye, interior, Exploration of, <a href="#Page_236">236</a>.</li>
+
+<li class="ifrst">Fall of Bodies, Rate of, <a href="#Page_16">16</a>.</li>
+
+<li class="indx">Falls, Height of, <a href="#Page_16">16</a>.</li>
+
+<li class="indx">Faraday, Genius and Character of, <a href="#Page_193">193</a>.</li>
+
+<li class="indx">Faraday’s Electrical Illustrations, <a href="#Page_214">214</a>.</li>
+
+<li class="indx">“Father of English Geology, the,” <a href="#Page_126">126</a>.</li>
+
+<li class="indx">Fertilisation of Clouds, <a href="#Page_151">151</a>.</li>
+
+<li class="indx">Fire, Perpetual, <a href="#Page_117">117</a>.</li>
+
+<li class="indx">Fire-balls and Shooting Stars, <a href="#Page_89">89</a>.</li>
+
+<li class="indx">Fire-Springs, Artesian, <a href="#Page_118">118</a>.</li>
+
+<li class="indx">Fishes, the most Ancient, <a href="#Page_132">132</a>.</li>
+
+<li class="indx">Flying Dragon, the, <a href="#Page_130">130</a>.</li>
+
+<li class="indx">Force neither created nor destroyed, <a href="#Page_18">18</a>.</li>
+
+<li class="indx">Force of Running Water, <a href="#Page_114">114</a>.</li>
+
+<li class="indx">Fossil Human Bones, <a href="#Page_131">131</a>.</li>
+
+<li class="indx">Fossil Meteoric Stones, none, <a href="#Page_92">92</a>.</li>
+
+<li class="indx">Fossil Rose, none, <a href="#Page_142">142</a>.</li>
+
+<li class="indx">Foucault’s Pendulum Experiments, <a href="#Page_22">22</a>.</li>
+
+<li class="indx">Franklin’s Electrical Kite, <a href="#Page_213">213</a>.</li>
+
+<li class="indx">Freezing Cavern in Russia, <a href="#Page_115">115</a>.</li>
+
+<li class="indx">Fresh Water in Mid-Ocean, <a href="#Page_182">182</a>.</li>
+
+<li class="ifrst">Galilean Telescope, the, <a href="#Page_93">93</a>.</li>
+
+<li class="indx">Galileo, What he first saw with the Telescope, <a href="#Page_93">93</a>.</li>
+
+<li class="indx">Galvani and Volta, <a href="#Page_205">205</a>.</li>
+
+<li class="indx">Galvanic Effects, Familiar, <a href="#Page_203">203</a>.</li>
+
+<li class="indx">Galvanic Waves on the same Wire, Non-interference of, <a href="#Page_225">225</a>.</li>
+
+<li class="indx">“Gauging the Heavens,” <a href="#Page_58">58</a>.</li>
+
+<li class="indx">Genius, Relics of, <a href="#Page_5">5</a>.</li>
+
+<li class="indx">Geology and Astronomy, Identity of, <a href="#Page_104">104</a>.</li>
+
+<li class="indx">Geology of England, <a href="#Page_105">105</a>.</li>
+
+<li class="indx">Geological Time, <a href="#Page_143">143</a>.</li>
+
+<li class="indx">George III., His patronage of Herschel, <a href="#Page_95">95</a>.</li>
+
+<li class="indx">Gilbert on Magnetic and Electric forces, <a href="#Page_201">201</a>.</li>
+
+<li class="indx">Glacial Theory, by Hopkins, <a href="#Page_105">105</a>.</li>
+
+<li class="indx">Glaciers, Antiquity of, <a href="#Page_109">109</a>.</li>
+
+<li class="indx">Glaciers, Phenomena of, Illustrated, <a href="#Page_108">108</a>.</li>
+
+<li class="indx">Glass, Benefits of, to Man, <a href="#Page_92">92</a>.</li>
+
+<li class="indx">Glass broken by Sand, <a href="#Page_26">26</a>.</li>
+
+<li class="indx">Glyptodon, the, <a href="#Page_137">137</a>.</li>
+
+<li class="indx">Gold, Lumps of, in Siberia, <a href="#Page_124">124</a>.</li>
+
+<li class="indx">Greenwich Observatory, Chronometers rated at, <a href="#Page_229">229&ndash;232</a>.</li>
+
+<li class="indx">Grotto del Cane, the, <a href="#Page_112">112</a>.</li>
+
+<li class="indx">Gulf-Stream and the Temperature of London, <a href="#Page_115">115</a>.</li>
+
+<li class="indx">Gunpowder-Magazines, Danger to, <a href="#Page_216">216</a>.</li>
+
+<li class="indx">Gymnotus and the Voltaic Battery, <a href="#Page_206">206</a>.</li>
+
+<li class="indx">Gyroscope, Foucault’s, <a href="#Page_22">22</a>.</li>
+
+<li class="ifrst">Hail and Storms, Protection against, <a href="#Page_159">159</a>.</li>
+
+<li class="indx">Hail-storm, Terrific, <a href="#Page_160">160</a>.</li>
+
+<li class="indx">Hair, Microscopical Examination of, <a href="#Page_41">41</a>.</li>
+
+<li class="indx">Harrison’s Prize Chronometers, <a href="#Page_229">229&ndash;232</a>.</li>
+
+<li class="indx">Heat and Evaporation, <a href="#Page_188">188</a>.</li>
+
+<li class="indx">Heat and Mechanical Power, <a href="#Page_188">188</a>.</li>
+
+<li class="indx">Heat by Friction, <a href="#Page_189">189</a>.</li>
+
+<li class="indx">Heat, Distinctions of, <a href="#Page_187">187</a>.</li>
+
+<li class="indx">Heat, Expenditure of, by the Sun, <a href="#Page_186">186</a>.<span class="pagenum"><a name="Page_245" id="Page_245">245</a></span></li>
+
+<li class="indx">Heat from Gas-lighting, <a href="#Page_189">189</a>.</li>
+
+<li class="indx">Heat from Wood and Ice, <a href="#Page_190">190</a>.</li>
+
+<li class="indx">Heat, Intense, Protection from, <a href="#Page_191">191</a>, <a href="#Page_192">192</a>.</li>
+
+<li class="indx">Heat, Latent, <a href="#Page_187">187</a>.</li>
+
+<li class="indx">Heat of Mines, <a href="#Page_188">188</a>.</li>
+
+<li class="indx">Heat, Nice Measurement of, <a href="#Page_186">186</a>.</li>
+
+<li class="indx">Heat, Origin of, in our System, <a href="#Page_87">87</a>.</li>
+
+<li class="indx">Heat passing through Glass, <a href="#Page_189">189</a>.</li>
+
+<li class="indx">Heat, Repulsion by, <a href="#Page_191">191</a>.</li>
+
+<li class="indx">Heated Metals, Vibration of, <a href="#Page_188">188</a>.</li>
+
+<li class="indx">Heavy Persons, Lifting, <a href="#Page_17">17</a>.</li>
+
+<li class="indx">Heights and Distances, to Calculate, <a href="#Page_19">19</a>.</li>
+
+<li class="indx">Herschel’s Telescopes at Slough, <a href="#Page_95">95</a>.</li>
+
+<li class="indx">Highton’s Minute Battery, <a href="#Page_204">204</a>.</li>
+
+<li class="indx">Hippopotamus of Britain, <a href="#Page_135">135</a>.</li>
+
+<li class="indx">“Horse Latitudes, the,” <a href="#Page_173">173</a>.</li>
+
+<li class="indx">Horse, Three-hoofed, <a href="#Page_138">138</a>.</li>
+
+<li class="indx">Hour-glass, Sand in the, <a href="#Page_20">20</a>.</li>
+
+<li class="ifrst">Ice, Heat from, <a href="#Page_190">190</a>.</li>
+
+<li class="indx">Ice, Warming with, <a href="#Page_190">190</a>.</li>
+
+<li class="indx">Icebergs of the Polar Seas, <a href="#Page_180">180</a>.</li>
+
+<li class="indx">Iguanodon, Food of the, <a href="#Page_129">129</a>.</li>
+
+<li class="indx">Improvement, Perpetuity of, <a href="#Page_5">5</a>.</li>
+
+<li class="indx">Inertia Illustrated, <a href="#Page_14">14</a>.</li>
+
+<li class="ifrst">Jerusalem, Temple of, How protected from Lightning, <a href="#Page_167">167</a>.</li>
+
+<li class="indx">Jew’s Harp, Theory of the, <a href="#Page_29">29</a>.</li>
+
+<li class="indx">Jupiter’s Satellites, Discovery of, <a href="#Page_80">80</a>.</li>
+
+<li class="ifrst">Kaleidoscope, Sir David Brewster’s, <a href="#Page_43">43</a>.</li>
+
+<li class="indx">Kaleidoscope, the, thought to be anticipated, <a href="#Page_43">43</a>.</li>
+
+<li class="indx">Kircher’s “Magnetism,” <a href="#Page_194">194</a>.</li>
+
+<li class="ifrst">Leaning Tower, Stability of, <a href="#Page_15">15</a>.</li>
+
+<li class="indx">Level, Curious Change of, <a href="#Page_144">144</a>.</li>
+
+<li class="indx">Leyden Jar, Origin of the, <a href="#Page_216">216</a>.</li>
+
+<li class="indx">Lifting Heavy Persons, <a href="#Page_17">17</a>.</li>
+
+<li class="indx">Light, Action of, on Muscular Fibres, <a href="#Page_34">34</a>.</li>
+
+<li class="indx">Light, Apparatus for Measuring, <a href="#Page_32">32</a>.</li>
+
+<li class="indx">Light from Buttons, <a href="#Page_36">36</a>.</li>
+
+<li class="indx">Light, Effect of, on the Magnet, <a href="#Page_198">198</a>.</li>
+
+<li class="indx">Light from Fungus, <a href="#Page_36">36</a>.</li>
+
+<li class="indx">Light from the Juice of a Plant, <a href="#Page_35">35</a>.</li>
+
+<li class="indx">Light, Importance of, <a href="#Page_34">34</a>.</li>
+
+<li class="indx">Light, Minuteness of, <a href="#Page_34">34</a>.</li>
+
+<li class="indx">Light Nights, <a href="#Page_35">35</a>.</li>
+
+<li class="indx">Light, Polarisation of, <a href="#Page_33">33</a>.</li>
+
+<li class="indx">Light, Solar and Artificial Compared, <a href="#Page_29">29</a>.</li>
+
+<li class="indx">Light, Source of, <a href="#Page_29">29</a>.</li>
+
+<li class="indx">Light, Undulatory Scale of, <a href="#Page_30">30</a>.</li>
+
+<li class="indx">Light, Velocity of, <a href="#Page_31">31</a>.</li>
+
+<li class="indx">Light, Velocity of, Measured by Fizeau, <a href="#Page_32">32</a>.</li>
+
+<li class="indx">Light from Quartz, <a href="#Page_51">51</a>.</li>
+
+<li class="indx">Lightning-Conductor, Ancient, <a href="#Page_167">167</a>.</li>
+
+<li class="indx">Lightning-Conductors, Service of, <a href="#Page_166">166</a>.</li>
+
+<li class="indx">Lightning Experiment, Fatal, <a href="#Page_214">214</a>.</li>
+
+<li class="indx">Lightning, Photographic Effects of, <a href="#Page_45">45</a>.</li>
+
+<li class="indx">Lightning produced by Rain, <a href="#Page_166">166</a>.</li>
+
+<li class="indx">Lightning, Sheet, What is it?, <a href="#Page_165">165</a>.</li>
+
+<li class="indx">Lightning, Varieties of, <a href="#Page_165">165</a>.</li>
+
+<li class="indx">Lightning, Various Effects of, <a href="#Page_168">168</a>.</li>
+
+<li class="indx">Log, Invention of the, <a href="#Page_173">173</a>.</li>
+
+<li class="indx">London Monument used as an Observatory, <a href="#Page_103">103</a>.</li>
+
+<li class="ifrst">“Maestricht Saurian Fossil,” the, <a href="#Page_141">141</a>.</li>
+
+<li class="indx">Magnet, Power of a, <a href="#Page_195">195</a>.</li>
+
+<li class="indx">Magnets, Artificial, How made, <a href="#Page_195">195</a>.</li>
+
+<li class="indx">Magnetic Clock and Watch, <a href="#Page_211">211</a>.</li>
+
+<li class="indx">Magnetic Electricity discovered, <a href="#Page_199">199</a>.</li>
+
+<li class="indx">Magnetic Hypotheses, <a href="#Page_193">193</a>.</li>
+
+<li class="indx">Magnetic Needle and the Chinese, <a href="#Page_194">194</a>.</li>
+
+<li class="indx">Magnetic Poles, North and South, <a href="#Page_201">201</a>.</li>
+
+<li class="indx">Magnetic Storms, <a href="#Page_202">202</a>.</li>
+
+<li class="indx">“Magnetism,” Kircher’s, <a href="#Page_194">194</a>.</li>
+
+<li class="indx">Malachite, How formed, <a href="#Page_124">124</a>.</li>
+
+<li class="indx">Mammalia in Secondary Rocks, <a href="#Page_130">130</a>.</li>
+
+<li class="indx">Mammoth of the British Isles, <a href="#Page_133">133</a>.</li>
+
+<li class="indx">Mammoth, Remains of the, <a href="#Page_134">134</a>.</li>
+
+<li class="indx">Mars, the Planet, Is it inhabited?, <a href="#Page_82">82</a>.</li>
+
+<li class="indx">Mastodon coexistent with Man, <a href="#Page_135">135</a>.</li>
+
+<li class="indx">Matter, Divisibility of, <a href="#Page_14">14</a>.</li>
+
+<li class="indx">Maury’s Physical Geography of the Sea, <a href="#Page_170">170</a>.</li>
+
+<li class="indx">Mediterranean, Depth of, <a href="#Page_176">176</a>.</li>
+
+<li class="indx">Megatherium, Habits of the, <a href="#Page_135">135</a>.</li>
+
+<li class="indx">Mercury, the Planet, Temperature of, <a href="#Page_82">82</a>.</li>
+
+<li class="indx">Mer de Glace, Flow of the, <a href="#Page_110">110</a>.<span class="pagenum"><a name="Page_246" id="Page_246">246</a></span></li>
+
+<li class="indx">Meteoric Stones, no Fossil, <a href="#Page_92">92</a>.</li>
+
+<li class="indx">Meteorites, Immense, <a href="#Page_91">91</a>.</li>
+
+<li class="indx">Meteorites from the Moon, <a href="#Page_89">89</a>.</li>
+
+<li class="indx">Meteors, Vast Shower of, <a href="#Page_91">91</a>.</li>
+
+<li class="indx">Microscope, the Eye, Brain, and Hair seen by, <a href="#Page_41">41</a>.</li>
+
+<li class="indx">Microscope, Fish-eye, How to make, <a href="#Page_40">40</a>.</li>
+
+<li class="indx">Microscope, Invention of the, <a href="#Page_39">39</a>.</li>
+
+<li class="indx">Microscope for Mineralogists, <a href="#Page_42">42</a>.</li>
+
+<li class="indx">Microscope and the Sea, <a href="#Page_42">42</a>.</li>
+
+<li class="indx">Microscopes, Diamond Lenses for, <a href="#Page_40">40</a>.</li>
+
+<li class="indx">Microscopes, Leuwenhoeck’s, <a href="#Page_40">40</a>.</li>
+
+<li class="indx">Microscopic Writing, <a href="#Page_42">42</a>.</li>
+
+<li class="indx">Milky Way, the, Unfathomable, <a href="#Page_85">85</a>.</li>
+
+<li class="indx">Mineralogy and Geometry, Union of, <a href="#Page_25">25</a>.</li>
+
+<li class="indx">Mirror, Magic, How to make, <a href="#Page_43">43</a>.</li>
+
+<li class="indx">Moon’s Attraction, the, <a href="#Page_73">73</a>.</li>
+
+<li class="indx">Moon, Has it an Atmosphere?, <a href="#Page_69">69</a>.</li>
+
+<li class="indx">Moon, Life in the, <a href="#Page_71">71</a>.</li>
+
+<li class="indx">Moon, Light of the, <a href="#Page_70">70</a>.</li>
+
+<li class="indx">Moon, Mountains in, <a href="#Page_72">72</a>.</li>
+
+<li class="indx">Moon, Measuring the Earth by, <a href="#Page_74">74</a>.</li>
+
+<li class="indx">Moon seen through the Rosse Telescope, <a href="#Page_72">72</a>.</li>
+
+<li class="indx">Moon, Scenery of, <a href="#Page_71">71</a>.</li>
+
+<li class="indx">Moon and Weather, the, <a href="#Page_73">73</a>.</li>
+
+<li class="indx">Moonlight, Heat of, <a href="#Page_70">70</a>.</li>
+
+<li class="indx">“More Worlds than One,” <a href="#Page_56">56</a>, <a href="#Page_57">57</a>.</li>
+
+<li class="indx">Mountain-chains, Elevation of, <a href="#Page_107">107</a>.</li>
+
+<li class="indx">Music of the Spheres, <a href="#Page_55">55</a>.</li>
+
+<li class="indx">Musket-balls found in Ivory, <a href="#Page_237">237</a>.</li>
+
+<li class="ifrst">Natural and Supernatural, the, <a href="#Page_6">6</a>.</li>
+
+<li class="indx">Nautical Almanac, Errors in, <a href="#Page_185">185</a>.</li>
+
+<li class="indx">Nebulæ, Distances of, <a href="#Page_85">85</a>.</li>
+
+<li class="indx">Nebular Hypothesis, the, <a href="#Page_86">86</a>.</li>
+
+<li class="indx">Neptune, the Planet, Discovery of, <a href="#Page_83">83</a>.</li>
+
+<li class="indx">Newton, Sir Isaac, his “Apple-tree,” <a href="#Page_8">8</a>.</li>
+
+<li class="indx">Newton upon Burnet’s Theory of the Earth, <a href="#Page_125">125</a>.</li>
+
+<li class="indx">Newton’s Dog “Diamond,” <a href="#Page_8">8</a>.</li>
+
+<li class="indx">Newton’s first Reflecting Telescope, <a href="#Page_94">94</a>.</li>
+
+<li class="indx">Newton’s “Principia,” <a href="#Page_9">9</a>.</li>
+
+<li class="indx">Newton’s Rooms at Cambridge, <a href="#Page_7">7</a>.</li>
+
+<li class="indx">Newton’s Scale of Colours, <a href="#Page_49">49</a>.</li>
+
+<li class="indx">Newton’s Soap-bubble Experiments, <a href="#Page_49">49</a>, <a href="#Page_50">50</a>.</li>
+
+<li class="indx">New Zealand, Extinct Birds of, <a href="#Page_139">139</a>.</li>
+
+<li class="indx">Niagara, the Roar of, <a href="#Page_28">28</a>.</li>
+
+<li class="indx">Nineveh, Rock-crystal Lens found at, <a href="#Page_39">39</a>.</li>
+
+<li class="indx">Non-conducting Bodies, <a href="#Page_215">215</a>.</li>
+
+<li class="indx">Nothing Lost in the Material World, <a href="#Page_18">18</a>.</li>
+
+<li class="ifrst">Objects really of no Colour, <a href="#Page_37">37</a>.</li>
+
+<li class="indx">Objects, Visibility of, <a href="#Page_30">30</a>.</li>
+
+<li class="indx">Observation, the Art of, <a href="#Page_3">3</a>.</li>
+
+<li class="indx">Observatory, Lacaille’s, <a href="#Page_101">101</a>.</li>
+
+<li class="indx">Observatory, the London Monument, <a href="#Page_103">103</a>.</li>
+
+<li class="indx">Observatory, Shirburn Castle, <a href="#Page_101">101</a>.</li>
+
+<li class="indx">Ocean and Air, Depths of unknown, <a href="#Page_174">174</a>.</li>
+
+<li class="indx">Ocean Highways, <a href="#Page_184">184</a>.</li>
+
+<li class="indx">Ocean, Stability of the, <a href="#Page_12">12</a>.</li>
+
+<li class="indx">Ocean, Transparency of the, <a href="#Page_171">171</a>.</li>
+
+<li class="indx">“Oldest piece of Wood upon the Earth,” <a href="#Page_142">142</a>.</li>
+
+<li class="indx">Optical Effects, Curious, at the Cape, <a href="#Page_38">38</a>.</li>
+
+<li class="indx">Optical Instruments, Late Invention of, <a href="#Page_100">100</a>.</li>
+
+<li class="indx">Oxford and Cambridge, Science at, <a href="#Page_1">1</a>.</li>
+
+<li class="ifrst">Pascal, How he weighed the Atmosphere, <a href="#Page_148">148</a>.</li>
+
+<li class="indx">Pebbles, on, <a href="#Page_106">106</a>.</li>
+
+<li class="indx">Pendulum Experiments, <a href="#Page_16">16&ndash;22</a>.</li>
+
+<li class="indx">Pendulum, the Earth weighed by, <a href="#Page_200">200</a>.</li>
+
+<li class="indx">Pendulums, Influence of on each other, <a href="#Page_200">200</a>.</li>
+
+<li class="indx">Perpetual Fire, <a href="#Page_117">117</a>.</li>
+
+<li class="indx">Petrifaction of Human Bodies, <a href="#Page_131">131</a>.</li>
+
+<li class="indx">Phenomena, Mutual Relations of, <a href="#Page_4">4</a>.</li>
+
+<li class="indx">Philosophers’ False Estimates, <a href="#Page_5">5</a>.</li>
+
+<li class="indx">Phosphorescence of Plants, <a href="#Page_35">35</a>.</li>
+
+<li class="indx">Phosphorescence of the Sea, <a href="#Page_35">35</a>.</li>
+
+<li class="indx">Photo-galvanic Engraving, <a href="#Page_47">47</a>.</li>
+
+<li class="indx">Photograph and Stereoscope, <a href="#Page_47">47</a>.</li>
+
+<li class="indx">Photographic effects of Lightning, <a href="#Page_45">45</a>.</li>
+
+<li class="indx">Photographic Surveying, <a href="#Page_46">46</a>.</li>
+
+<li class="indx">Photographs on the Retina, <a href="#Page_236">236</a>.</li>
+
+<li class="indx">Photography, Best Sky for, <a href="#Page_45">45</a>.</li>
+
+<li class="indx">Photography, Magic of, <a href="#Page_44">44</a>.</li>
+
+<li class="indx">Pisa, Leaning Tower of, <a href="#Page_15">15</a>.</li>
+
+<li class="indx">Planetary System, Origin of our, <a href="#Page_86">86</a>.</li>
+
+<li class="indx">Planets, Diversities of, <a href="#Page_79">79</a>.</li>
+
+<li class="indx">Planetoids, List of the, and their Discoverers, <a href="#Page_239">239</a>.</li>
+
+<li class="indx">Plato’s Survey of the Sciences, <a href="#Page_2">2</a>.<span class="pagenum"><a name="Page_247" id="Page_247">247</a></span></li>
+
+<li class="indx">Pleiades, the, <a href="#Page_77">77</a>.</li>
+
+<li class="indx">Plurality of Worlds, <a href="#Page_57">57</a>.</li>
+
+<li class="indx">Polar Ice, Immensity of, <a href="#Page_181">181</a>.</li>
+
+<li class="indx">Polar Iceberg, <a href="#Page_180">180</a>.</li>
+
+<li class="indx">Polarisation of Light, <a href="#Page_33">33</a>.</li>
+
+<li class="indx">Pole, Open Sea at the, <a href="#Page_181">181</a>.</li>
+
+<li class="indx">Pole-Star of 4000 years ago, <a href="#Page_76">76</a>.</li>
+
+<li class="indx">Profitable Science, <a href="#Page_139">139</a>.</li>
+
+<li class="indx">Pterodactyl, the, <a href="#Page_130">130</a>.</li>
+
+<li class="indx">Pyramid, Duration of the, <a href="#Page_14">14</a>.</li>
+
+<li class="ifrst">Quartz, Down of, <a href="#Page_42">42</a>.</li>
+
+<li class="ifrst">Rain, All in the World, <a href="#Page_155">155</a>.</li>
+
+<li class="indx">Rain, an Inch on the Atlantic, <a href="#Page_156">156</a>.</li>
+
+<li class="indx">Rain-Drops, Size of, <a href="#Page_154">154</a>.</li>
+
+<li class="indx">Rain, How the North Wind drives it away, <a href="#Page_154">154</a>.</li>
+
+<li class="indx">Rain, Philosophy of, <a href="#Page_153">153</a>.</li>
+
+<li class="indx">Rainless Districts, <a href="#Page_155">155</a>.</li>
+
+<li class="indx">Rain-making Vapour, from South to North, <a href="#Page_152">152</a>.</li>
+
+<li class="indx">Rainy Climate, Inordinate, <a href="#Page_154">154</a>.</li>
+
+<li class="indx">Red Sea and Mediterranean Levels, <a href="#Page_175">175</a>.</li>
+
+<li class="indx">Red Sea, Colour of, <a href="#Page_176">176</a>.</li>
+
+<li class="indx">Repulsion of Bodies, <a href="#Page_216">216</a>.</li>
+
+<li class="indx">Rhinoceros of Britain, <a href="#Page_135">135</a>.</li>
+
+<li class="indx">River-water on the Ocean, <a href="#Page_181">181</a>.</li>
+
+<li class="indx">Rose, no Fossil, <a href="#Page_142">142</a>.</li>
+
+<li class="indx">Rosse, the Earl of, his “Telescope,” <a href="#Page_96">96&ndash;99</a>.</li>
+
+<li class="indx">Rotation-Magnetism discovered, <a href="#Page_199">199</a>.</li>
+
+<li class="indx">Rotation, the Axis of, <a href="#Page_11">11</a>.</li>
+
+<li class="ifrst">St. Paul’s Cathedral, how protected from Lightning, <a href="#Page_167">167</a>.</li>
+
+<li class="indx">Salt, All in the Sea, <a href="#Page_179">179</a>.</li>
+
+<li class="indx">Salt Lake of Utah, <a href="#Page_113">113</a>.</li>
+
+<li class="indx">Salt, Solvent Action of, <a href="#Page_115">115</a>.</li>
+
+<li class="indx">Saltness of the Sea, How to tell, <a href="#Page_179">179</a>.</li>
+
+<li class="indx">Sand in the Hour-glass, <a href="#Page_20">20</a>.</li>
+
+<li class="indx">Sand of the Sea and Desert, <a href="#Page_106">106</a>.</li>
+
+<li class="indx">Saturn’s Ring, Was it known to the Ancients?, <a href="#Page_81">81</a>.</li>
+
+<li class="indx">Schwabe, on Sun-Spots, <a href="#Page_68">68</a>.</li>
+
+<li class="indx">Science at Oxford and Cambridge, <a href="#Page_1">1</a>.</li>
+
+<li class="indx">Science of the Ancient World, <a href="#Page_1">1</a>.</li>
+
+<li class="indx">Science, Theoretical, Practical Results of, <a href="#Page_4">4</a>.</li>
+
+<li class="indx">Sciences, Plato’s Survey of, <a href="#Page_2">2</a>.</li>
+
+<li class="indx">Scientific Treatise, the Earliest English, <a href="#Page_5">5</a>.</li>
+
+<li class="indx">Scoresby, Dr., on the Rosse Telescope, <a href="#Page_99">99</a>.</li>
+
+<li class="indx">Scratches, Colours of, <a href="#Page_36">36</a>.</li>
+
+<li class="indx">Sea, Bottles and Currents at, <a href="#Page_172">172</a>.</li>
+
+<li class="indx">Sea, Bottom of, a burial-place, <a href="#Page_177">177</a>.</li>
+
+<li class="indx">Sea, Circulation of the, <a href="#Page_170">170</a>.</li>
+
+<li class="indx">Sea, Climates of the, <a href="#Page_170">170</a>.</li>
+
+<li class="indx">Sea, Deep, Life of the, <a href="#Page_174">174</a>.</li>
+
+<li class="indx">Sea, Greatest ascertained Depth of, <a href="#Page_175">175</a>.</li>
+
+<li class="indx">Sea, Solitude at, <a href="#Page_172">172</a>.</li>
+
+<li class="indx">Sea, Temperature of the, <a href="#Page_170">170</a>.</li>
+
+<li class="indx">Sea, Why is it Salt?, <a href="#Page_177">177</a>.</li>
+
+<li class="indx">Seas, Primeval, Depth of, <a href="#Page_234">234</a>.</li>
+
+<li class="indx">Sea-breezes and Land-breezes illustrated, <a href="#Page_150">150</a>.</li>
+
+<li class="indx">Sea-milk, What is it?, <a href="#Page_176">176</a>.</li>
+
+<li class="indx">Sea-routes, How shortened, <a href="#Page_184">184</a>.</li>
+
+<li class="indx">Sea-shells and Animalcules, Services of, <a href="#Page_234">234</a>.</li>
+
+<li class="indx">Sea-shells, Why found at Great Heights, <a href="#Page_106">106</a>.</li>
+
+<li class="indx">Sea-water, to imitate, <a href="#Page_235">235</a>.</li>
+
+<li class="indx">Sea-water, Properties of, <a href="#Page_179">179</a>.</li>
+
+<li class="indx">Serapis, Temple of, Successive Changes in, <a href="#Page_111">111</a>.</li>
+
+<li class="indx">Sheep, Geology of the, <a href="#Page_138">138</a>.</li>
+
+<li class="indx">Shells, Geometry of, <a href="#Page_232">232</a>.</li>
+
+<li class="indx">Shells, Hydraulic Theory of, <a href="#Page_233">233</a>.</li>
+
+<li class="indx">Siamese Twins, the, galvanised, <a href="#Page_203">203</a>.</li>
+
+<li class="indx">Skin, Dark Colour of the, <a href="#Page_63">63</a>.</li>
+
+<li class="indx">Smith, William, the Geologist, <a href="#Page_126">126</a>.</li>
+
+<li class="indx">Snow, Absence of in Siberia, <a href="#Page_159">159</a>.</li>
+
+<li class="indx">Snow, Impurity of, <a href="#Page_158">158</a>.</li>
+
+<li class="indx">Snow Phenomenon, <a href="#Page_158">158</a>.</li>
+
+<li class="indx">Snow, Warmth of, in Arctic Latitudes, <a href="#Page_158">158</a>.</li>
+
+<li class="indx">Snow-capped Volcano, the, <a href="#Page_119">119</a>.</li>
+
+<li class="indx">Snow-crystals observed by the Chinese, <a href="#Page_159">159</a>.</li>
+
+<li class="indx">Soap-bubble, Science of the, <a href="#Page_48">48</a>.</li>
+
+<li class="indx">Solar Heat, Extreme, <a href="#Page_63">63</a>.</li>
+
+<li class="indx">Solar System, Velocity of, <a href="#Page_59">59</a>.</li>
+
+<li class="indx">Sound, Figures produced by, <a href="#Page_28">28</a>.</li>
+
+<li class="indx">Sound in rarefied Air, <a href="#Page_27">27</a>.</li>
+
+<li class="indx">Sounding Sand, <a href="#Page_27">27</a>.</li>
+
+<li class="indx">Space, Infinite, <a href="#Page_86">86</a>.</li>
+
+<li class="indx">Speed, Varieties of, <a href="#Page_17">17</a>.</li>
+
+<li class="indx">Spheres, Music of the, <a href="#Page_55">55</a>.</li>
+
+<li class="indx">Spots on the Sun, <a href="#Page_67">67</a>.</li>
+
+<li class="indx">Star, Fixed, the nearest, <a href="#Page_78">78</a>.</li>
+
+<li class="indx">Stars’ Colour, Change in, <a href="#Page_77">77</a>.</li>
+
+<li class="indx">Star’s Light sixteen times that of the Sun, <a href="#Page_79">79</a>.</li>
+
+<li class="indx">Stars, Number of, <a href="#Page_75">75</a>.<span class="pagenum"><a name="Page_248" id="Page_248">248</a></span></li>
+
+<li class="indx">Stars seen by Daylight, <a href="#Page_102">102</a>.</li>
+
+<li class="indx">Stars that have disappeared, <a href="#Page_76">76</a>.</li>
+
+<li class="indx">Stars, Why created, <a href="#Page_75">75</a>.</li>
+
+<li class="indx">Stereoscope and Photograph, <a href="#Page_47">47</a>.</li>
+
+<li class="indx">Stereoscope simplified, <a href="#Page_47">47</a>.</li>
+
+<li class="indx">Storm, Impetus of, <a href="#Page_164">164</a>.</li>
+
+<li class="indx">Storms, Revolving, <a href="#Page_164">164</a>.</li>
+
+<li class="indx">Storms, to tell the Approach of, <a href="#Page_163">163</a>.</li>
+
+<li class="indx">Storm-glass, How to make, <a href="#Page_164">164</a>.</li>
+
+<li class="indx">Succession of life in Time, <a href="#Page_128">128</a>.</li>
+
+<li class="indx">Sun, Actinic Power of, <a href="#Page_62">62</a>.</li>
+
+<li class="indx">Sun and Fixed Stars’ Light compared, <a href="#Page_64">64</a>.</li>
+
+<li class="indx">Sun and Terrestrial Magnetism, <a href="#Page_64">64</a>.</li>
+
+<li class="indx">“Sun Darkened,” <a href="#Page_64">64</a>.</li>
+
+<li class="indx">Sun, Great Size of, on Horizon, <a href="#Page_61">61</a>.</li>
+
+<li class="indx">Sun, Heating Power of, <a href="#Page_62">62</a>.</li>
+
+<li class="indx">Sun, Lost Heat of, <a href="#Page_103">103</a>.</li>
+
+<li class="indx">Sun, Luminous Disc of, <a href="#Page_60">60</a>.</li>
+
+<li class="indx">Sun, Nature of the, <a href="#Page_59">59</a>, <a href="#Page_238">238</a>.</li>
+
+<li class="indx">Sun, Spots on, <a href="#Page_67">67</a>.</li>
+
+<li class="indx">Sun, Translatory Motion of, <a href="#Page_61">61</a>.</li>
+
+<li class="indx">Sun’s Distance by the Yard Measure, <a href="#Page_66">66</a>.</li>
+
+<li class="indx">Sun’s Heat, Is it decreasing?, <a href="#Page_65">65</a>.</li>
+
+<li class="indx">Sun’s Rays increasing the Strength of Magnets, <a href="#Page_196">196</a>.</li>
+
+<li class="indx">Sun’s Light and Terrestrial Lights, <a href="#Page_61">61</a>.</li>
+
+<li class="indx">Sun-dial, Universal, <a href="#Page_65">65</a>.</li>
+
+<li class="ifrst">Telegraph, the Atlantic, <a href="#Page_226">226</a>.</li>
+
+<li class="indx">Telegraph, the Electric, <a href="#Page_220">220</a>.</li>
+
+<li class="indx">Telescope and Microscope, the, <a href="#Page_38">38</a>.</li>
+
+<li class="indx">Telescope, Galileo’s, <a href="#Page_93">93</a>.</li>
+
+<li class="indx">Telescope, Herschel’s, <a href="#Page_95">95</a>.</li>
+
+<li class="indx">Telescope, Newton’s first Reflecting, <a href="#Page_94">94</a>.</li>
+
+<li class="indx">Telescopes, Antiquity of, <a href="#Page_94">94</a>.</li>
+
+<li class="indx">Telescopes, Gigantic, proposed, <a href="#Page_99">99</a>.</li>
+
+<li class="indx">Telescopes, the Earl of Rosse’s, <a href="#Page_96">96</a>.</li>
+
+<li class="indx">Temperature and Electricity, <a href="#Page_208">208</a>.</li>
+
+<li class="indx">Terrestrial Magnetism, Origin of, <a href="#Page_200">200</a>.</li>
+
+<li class="indx">Thames, the, and its Salt-water Bed, <a href="#Page_182">182</a>.</li>
+
+<li class="indx">Threads, the two Electric, <a href="#Page_215">215</a>.</li>
+
+<li class="indx">Thunderstorm seen from a Balloon, <a href="#Page_169">169</a>.</li>
+
+<li class="indx">Tides, How produced by Sun and Moon, <a href="#Page_66">66</a>.</li>
+
+<li class="indx">Time an Element of Force, <a href="#Page_19">19</a>.</li>
+
+<li class="indx">Time, Minute Measurement of, <a href="#Page_194">194</a>.</li>
+
+<li class="indx">Topaz, Transmutation of, <a href="#Page_37">37</a>.</li>
+
+<li class="indx">Trilobite, the, <a href="#Page_138">138</a>.</li>
+
+<li class="indx">Tuning-fork a Flute-player, <a href="#Page_28">28</a>.</li>
+
+<li class="indx">Twilight, Beauty of, <a href="#Page_148">148</a>.</li>
+
+<li class="ifrst">Universe, Vast Numbers in, <a href="#Page_75">75</a>.</li>
+
+<li class="indx">Utah, Salt Lake of, <a href="#Page_113">113</a>.</li>
+
+<li class="ifrst">Velocity of the Solar System, <a href="#Page_59">59</a>.</li>
+
+<li class="indx">Vesta and Pallas, Speculations on, <a href="#Page_82">82</a>.</li>
+
+<li class="indx">Vesuvius, Great Eruptions of, <a href="#Page_119">119</a>.</li>
+
+<li class="indx">Vibration of Heated Metals, <a href="#Page_188">188</a>.</li>
+
+<li class="indx">Visibility of Objects, <a href="#Page_30">30</a>.</li>
+
+<li class="indx">Voice, Human, Audibility of, <a href="#Page_27">27</a>.</li>
+
+<li class="indx">Volcanic Action and Geological Change, <a href="#Page_118">118</a>.</li>
+
+<li class="indx">Volcanic Dust, Travels of, <a href="#Page_119">119</a>.</li>
+
+<li class="indx">Volcanic Islands, Disappearance of, <a href="#Page_117">117</a>.</li>
+
+<li class="indx">Voltaic Battery and the Gymnotus, <a href="#Page_206">206</a>.</li>
+
+<li class="indx">Voltaic Currents in Mines, <a href="#Page_206">206</a>.</li>
+
+<li class="indx">Voltaic Electricity discovered, <a href="#Page_205">205</a>.</li>
+
+<li class="ifrst">Watches, Harrison’s Prize, <a href="#Page_229">229</a>.</li>
+
+<li class="indx">Water decomposed by Electricity, <a href="#Page_208">208</a>.</li>
+
+<li class="indx">Water, Running, Force of, <a href="#Page_114">114</a>.</li>
+
+<li class="indx">Waters of the Globe gradually decreasing, <a href="#Page_113">113</a>.</li>
+
+<li class="indx">Water-Purifiers, Natural, <a href="#Page_234">234</a>.</li>
+
+<li class="indx">Waterspouts, How formed in the Java Sea, <a href="#Page_160">160</a>.</li>
+
+<li class="indx">Waves, Cause of, <a href="#Page_183">183</a>.</li>
+
+<li class="indx">Waves, Force of, <a href="#Page_184">184</a>.</li>
+
+<li class="indx">Waves, Rate of Travelling, <a href="#Page_183">183</a>.</li>
+
+<li class="indx">Wenham-Lake Ice, Purity of, <a href="#Page_161">161</a>.</li>
+
+<li class="indx">West, Superior Salubrity of, <a href="#Page_150">150</a>.</li>
+
+<li class="indx">“White Water,” and Luminous Animals at Sea, <a href="#Page_173">173</a>.</li>
+
+<li class="indx">Winds, Transporting Power of, <a href="#Page_163">163</a>.</li>
+
+<li class="indx">Wollaston’s Minute Battery, <a href="#Page_204">204</a>.</li>
+
+<li class="indx">World, All the, in Motion, <a href="#Page_11">11</a>.</li>
+
+<li class="indx">World, the, in a Nutshell, <a href="#Page_13">13</a>.</li>
+
+<li class="indx">Worlds, More than One, <a href="#Page_56">56</a>.</li>
+
+<li class="indx">Worlds to come, <a href="#Page_58">58</a>.</li>
+</ul>
+</div>
+
+<p class="p2 center small">LONDON: ROBSON, LEVEY, AND FRANKLYN, GREAT NEW STREET AND PETTER LANE, E.C.</p>
+
+<div class="chapter"></div>
+<div class="transnote">
+<h2 class="nobreak"><a name="Transcribers_Notes" id="Transcribers_Notes"></a>Transcriber’s Notes</h2>
+
+<p>Punctuation, hyphenation, and spelling were made consistent when a predominant
+preference was found in this book; otherwise they were not changed.</p>
+
+<p>Simple typographical errors were corrected; occasional unbalanced
+quotation marks retained.</p>
+
+<p>Ambiguous hyphens at the ends of lines were retained.</p>
+
+<p>Some numbers in equations include a hyphen to separate
+the fractional and integer parts. These are not minus signs,
+which, like other arithmetic operators, are surrounded by spaces.</p>
+
+<p>The original book apparently used a smaller font for multiple
+reasons, but as those reasons were not always clear to the
+Transcriber, smaller text is indented by 2 spaces in the Plain Text
+version of this eBook, and is displayed smaller in other versions.</p>
+
+<p>Footnotes, originally at the bottoms of pages, have been
+collected and repositioned just before the Index.</p>
+
+<p>Devices that cannot display some of the characters used for column
+alignment in the tables of this eBook may substitute question marks
+or hollow squares.</p>
+
+<p>Page <a href="#Page_59">59</a>: “95 × 1·623 = 154·185” was misprinted as
+“95 + 1·623 = 154·185” and has been corrected here.</p>
+
+<p>The Table of Contents does not list the “<a href="#Phenomena">Phenomena of Heat</a>”
+chapter, which begins on page <a href="#Page_185">185</a>; nor the <a href="#GENERAL_INDEX">Index</a>, which
+begins on page <a href="#Page_242">242</a>.</p>
+
+<p>Page <a href="#Page_95">95</a>: “adjustible” was printed that way.</p>
+
+<p>Page <a href="#Page_151">151</a>: Missing closing quotation mark added after
+“rapidly evaporate in space.” It may belong elsewhere.</p>
+
+<p>Page <a href="#Page_221">221</a>: Missing closing quotation mark not added for
+phrase beginning “it is a fine invention”.</p>
+</div>
+
+<div>*** END OF THE PROJECT GUTENBERG EBOOK 48516 ***</div>
+</body>
+</html>
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