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+The Project Gutenberg eBook of The New Astronomy, by Samuel Pierpont
+Langley
+
+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
+will have to check the laws of the country where you are located before
+using this eBook.
+
+Title: The New Astronomy
+
+Author: Samuel Pierpont Langley
+
+Release Date: February 16, 2021 [eBook #64577]
+
+Language: English
+
+Character set encoding: UTF-8
+
+Produced by: Tim Lindell, Charlie Howard, and the Online Distributed
+             Proofreading Team at https://www.pgdp.net (This file was
+             produced from images generously made available by The Internet
+             Archive/American Libraries.)
+
+*** START OF THE PROJECT GUTENBERG EBOOK THE NEW ASTRONOMY ***
+
+
+
+
+THE NEW ASTRONOMY
+
+
+
+
+  THE NEW ASTRONOMY
+
+
+  BY
+
+  SAMUEL PIERPONT LANGLEY, PH.D., LL.D.
+
+  DIRECTOR OF THE ALLEGHENY OBSERVATORY, MEMBER NATIONAL ACADEMY,
+  FELLOW ROYAL ASTRONOMICAL SOCIETY, ETC., ETC.
+
+
+  Illustrated
+
+
+  [Illustration]
+
+
+  BOSTON.
+  TICKNOR AND COMPANY
+  211 Tremont Street
+  1888
+
+
+
+
+  COPYRIGHT, 1884, 1885, 1886, AND 1887, BY THE CENTURY CO.;
+  AND 1887, BY S. P. LANGLEY.
+
+  _All rights reserved._
+
+  University Press:
+  JOHN WILSON AND SON, CAMBRIDGE.
+
+
+
+
+PREFACE.
+
+
+I have written these pages, not for the professional reader, but with
+the hope of reaching a part of that educated public on whose support
+he is so often dependent for the means of extending the boundaries of
+knowledge.
+
+It is not generally understood that among us not only the support
+of the Government, but with scarcely an exception every new private
+benefaction, is devoted to “the Old” Astronomy, which is relatively
+munificently endowed already; while that which I have here called “the
+New,” so fruitful in results of interest and importance, struggles
+almost unaided.
+
+We are all glad to know that Urania, who was in the beginning but a
+poor Chaldean shepherdess, has long since become well-to-do, and dwells
+now in state. It is far less known than it should be that she has a
+younger sister now among us, bearing every mark of her celestial birth,
+but all unendowed and portionless. It is for the reader’s interest in
+the latter that this book is a plea.
+
+
+
+
+CONTENTS.
+
+
+  CHAPTER                                                           PAGE
+
+     I.   SPOTS ON THE SUN                                             1
+
+    II.   THE SUN’S SURROUNDINGS                                      35
+
+   III.   THE SUN’S ENERGY                                            70
+
+    IV.   THE SUN’S ENERGY (_Continued_)                              91
+
+     V.   THE PLANETS AND THE MOON                                   117
+
+    VI.   METEORS                                                    175
+
+   VII.   COMETS                                                     199
+
+  VIII.   THE STARS                                                  221
+
+
+  INDEX                                                              253
+
+
+
+
+LIST OF ILLUSTRATIONS.
+
+
+  FIGURE                                                            PAGE
+
+   1.  THE SUN’S SURROUNDINGS                                          4
+
+   2.  VIEW OF THE SUN ON SEPT. 20, 1870                               6
+
+   3.  THE SUN ON SEPT. 22, 1870                                       6
+
+   4.  THE SUN ON SEPT. 26, 1870                                       7
+
+   5.  THE SUN ON SEPT. 19, 1870                                       8
+
+   6.  THE SUN ON SEPT. 20, 1870                                       8
+
+   7.  THE SUN ON SEPT. 21, 1870                                       9
+
+   8.  THE SUN ON SEPT. 22, 1870                                       9
+
+   9.  THE SUN ON SEPT. 23, 1870                                      10
+
+  10.  THE SUN ON SEPT. 26, 1870                                      10
+
+  11.  NASMYTH’S WILLOW LEAVES                                        11
+
+  12.  THE CACTUS TYPE                                                12
+
+  13.  EQUATORIAL TELESCOPE AND PROJECTION                            13
+
+  14.  POLARIZING EYE-PIECE                                           14
+
+  15.  SPOT OF SEPT. 21, 1870                                         15
+
+  16.  SPOT OF MARCH 5, 1873                                          15
+
+  17.  SUN ON MARCH 5, 1873                                           18
+
+  18.  “THE PLUME” SPOT OF MARCH 5 AND 6, 1873                        19
+
+  19.  TYPICAL SUN-SPOT OF DECEMBER, 1873                             21
+
+  20.  FROST CRYSTAL                                                  23
+
+  21.  CYCLONE SPOT                                                   24
+
+  22.  SPOT OF MARCH 31, 1875                                         25
+
+  23.  CIRROUS CLOUD                                                  27
+
+  24.  SPOT OF MARCH 31, 1875                                         28
+
+  25.  TYPICAL ILLUSTRATION OF FAYE’S THEORY                          29
+
+  26.  SPOT OF OCT. 13, 1876                                          30
+
+  27.  PHOTOGRAPH OF EDGE OF SUN                                      31
+
+  28.  FACULA                                                         33
+
+  29.  LUNAR CONE SHADOW                                              36
+
+  30.  TRACK OF LUNAR SHADOW                                          39
+
+  31.  INNER CORONA ECLIPSE OF 1869                                   40
+
+  32.  SKETCH OF OUTER CORONA, 1869                                   41
+
+  33.  TACCHINI’S DRAWING OF CORONA OF 1870                           43
+
+  34.  WATSON’S NAKED-EYE DRAWING OF CORONA OF 1870                   44
+
+  35.  PHOTOGRAPH SHOWING COMMENCEMENT OF OUTER CORONA                45
+
+  36.  ECLIPSE OF 1857, DRAWING BY LIAIS                              48
+
+  37.  ENLARGEMENT OF PART OF FIG. 38                                 49
+
+  38.  FAC-SIMILE OF PHOTOGRAPH OF CORONA OF 1871                     51
+
+  39.  “SPECTRES”                                                     54
+
+  40.  OUTER CORONA OF 1878                                           57
+
+  41.  SPECTROSCOPE SLIT AND SOLAR IMAGE                              59
+
+  42.  SLIT AND PROMINENCES                                           59
+
+  43.  TACCHINI’S CHROMOSPHERIC CLOUDS                                62
+
+  44.  TACCHINI’S CHROMOSPHERIC CLOUDS                                62
+
+  45.  VOGEL’S CHROMOSPHERIC FORMS                                    64
+
+  46.  TACCHINI’S CHROMOSPHERIC FORMS                                 66
+
+  47.  ERUPTIVE PROMINENCES                                           67
+
+  48.  SUN-SPOTS AND PRICE OF GRAIN                                   77
+
+  49.  SUN-SPOT OF NOV. 16, 1882, AND EARTH                           80
+
+  50.  GREENWICH RECORD OF DISTURBANCE OF MAGNETIC NEEDLE,
+         NOV. 16 AND 17, 1882                                         81
+
+  51.  SUN-SPOTS AND MAGNETIC VARIATIONS                              87
+
+  52.  GREENWICH MAGNETIC OBSERVATIONS, AUG. 3 AND 5, 1872            89
+
+  53.  ONE CUBIC CENTIMETRE                                           93
+
+  54.  POUILLET’S PYRHELIOMETER                                       93
+
+  55.  BERNIÈRES’S GREAT BURNING-GLASS                               103
+
+  56.  A “POUR” FROM THE BESSEMER CONVERTER                          105
+
+  57.  PHOTOMETER-BOX                                                108
+
+  58.  MOUCHOT’S SOLAR ENGINE                                        109
+
+  59.  ERICSSON’S NEW SOLAR ENGINE, NOW IN PRACTICAL USE IN NEW
+         YORK                                                        113
+
+  60.  SATURN                                                        119
+
+  61.  THE EQUATORIAL TELESCOPE AT WASHINGTON                        122
+
+  62.  JUPITER, MOON, AND SHADOW                                     125
+
+  63.  THREE VIEWS OF MARS                                           129
+
+  64.  MAP OF MARS                                                   129
+
+  65.  THE MOON                                                      137
+
+  66.  THE FULL MOON                                                 141
+
+  67.  GLASS GLOBE, CRACKED                                          145
+
+  68.  PLATO AND THE LUNAR ALPS                                      149
+
+  69.  THE LUNAR APENNINES: ARCHIMEDES                               153
+
+  70.  VESUVIUS AND NEIGHBORHOOD OF NAPLES                           157
+
+  71.  PTOLEMY AND ARZACHEL                                          161
+
+  72.  MERCATOR AND CAMPANUS                                         165
+
+  73.  WITHERED HAND                                                 168
+
+  74.  IDEAL LUNAR LANDSCAPE AND EARTH-SHINE                         169
+
+  75.  WITHERED APPLE                                                171
+
+  76.  GASSENDI. NOV. 7, 1867                                        173
+
+  77.  THE CAMP AT MOUNT WHITNEY                                     177
+
+  78.  VESUVIUS DURING AN ERUPTION                                   183
+
+  79.  METEORS OBSERVED NOV. 13 AND 14, 1868, BETWEEN MIDNIGHT
+         AND FIVE O’CLOCK, A. M.                                     189
+
+  80.  COMET OF DONATI, SEPT. 16, 1858                               201
+
+  81.  “A PART OF A COMET”                                           203
+
+  82.  COMET OF DONATI, SEPT. 24, 1858                               205
+
+  83.  COMET OF DONATI, OCT. 3, 1858                                 209
+
+  84.  COMET OF DONATI, OCT. 9, 1858                                 213
+
+  85.  COMET OF DONATI, OCT. 5, 1858                                 217
+
+  86.  TYPES OF STELLAR SPECTRA                                      222
+
+  87.  THE MILKY WAY                                                 225
+
+  88.  SPECTRA OF STARS IN PLEIADES                                  231
+
+  89.  SPECTRUM OF ALDEBARAN                                         235
+
+  90.  SPECTRUM OF VEGA                                              235
+
+  91.  GREAT NEBULA IN ORION                                         239
+
+  92.  A FALLING MAN                                                 243
+
+  93.  A FLASH OF LIGHTNING                                          245
+
+
+
+
+THE NEW ASTRONOMY.
+
+
+
+
+I.
+
+SPOTS ON THE SUN.
+
+
+The visitor to Salisbury Plain sees around him a lonely waste,
+utterly barren except for a few recently planted trees, and otherwise
+as desolate as it could have been when Hengist and Horsa landed in
+Britain; for its monotony is still unbroken except by the funeral
+mounds of ancient chiefs, which dot it to its horizon, and contrast
+strangely with the crowded life and fertile soil which everywhere
+surround its borders. In the midst of this loneliness rise the rude,
+enormous monoliths of Stonehenge,--circles of gray stones, which seem
+as old as time, and were there, as we now are told, the temple of a
+people which had already passed away, and whose worship was forgotten,
+when our Saxon forefathers first saw the place.
+
+In the centre of the inner circle is a stone which is believed once
+to have been the altar; while beyond the outmost ring, quite away to
+the northeast upon the open plain, still stands a solitary stone,
+set up there evidently with some special object by the same unknown
+builders. Seen under ordinary circumstances, it is difficult to divine
+its connection with the others; but we are told that once in each
+year, upon the morning of the longest day, the level shadow of this
+distant, isolated stone is projected at sunrise to the very centre of
+the ancient sanctuary, and falls just upon the altar. The primitive
+man who devised this was both astronomer and priest, for he not only
+adored the risen god whose first beams brought him light and warmth,
+but he could mark its place, and though utterly ignorant of its nature,
+had evidently learned enough of its motions to embody his simple
+astronomical knowledge in a record so exact and so enduring that though
+his very memory has gone, common men are still interested in it; for,
+as I learned when viewing the scene, people are accustomed to come from
+all the surrounding country, and pass in this desolate spot the short
+night preceding the longest day of the year, to see the shadow touch
+the altar at the moment of sunrise.
+
+Most great national observatories, like Greenwich or Washington,
+are the perfected development of that kind of astronomy of which
+the builders of Stonehenge represent the infancy. Those primitive
+men could know where the sun would rise on a certain day, and make
+their observation of its place, as we see, very well, without knowing
+anything of its physical nature. At Greenwich the moon has been
+observed with scarcely an intermission for one hundred and fifty
+years, but we should mistake greatly did we suppose that it was for
+the purpose of seeing what it was made of, or of making discoveries in
+it. This immense mass of Greenwich observations is for quite another
+purpose,--for the very practical purpose of forming the lunar tables,
+which, by means of the moon’s place among the stars, will tell the
+navigator in distant oceans where he is, and conduct the fleets of
+England safely home.
+
+In the observatory at Washington one may see a wonderfully exact
+instrument, in which circles of brass have replaced circles of stone,
+all so bolted between massive piers that the sun can be observed by
+it but once daily, as it crosses the meridian. This instrument is the
+completed attainment along that long line of progress in one direction,
+of which the solitary stone at Stonehenge marks the initial step,--the
+attainment, that is, purely of precision of measurement; for the
+astronomer of to-day can still use his circles for the special purpose
+of fixing the sun’s place in the heavens, without any more knowledge of
+that body’s chemical constitution than had the man who built Stonehenge.
+
+Yet the object of both is, in fact, the same. It is true that the
+functions of astronomer and priest have become divided in the advance
+of our modern civilization, which has committed the special cultivation
+of the religious aspect of these problems to a distinct profession;
+while the modern observer has possibly exchanged the emotions of awe
+and wonder for a more exact knowledge of the equinox than was possessed
+by his primitive brother, who both observed and adored. Still, both
+aim at the common end, not of learning what the sun is made of, but
+of where it will be at a certain moment; for the prime object of
+astronomy, until very lately indeed, has still been to say _where_
+any heavenly body is, and not _what_ it is. It is this precision of
+measurement, then, which has always--and justly--been a paramount
+object of this oldest of the sciences, not only as a good in itself,
+but as leading to great ends; and it is this which the poet of Urania
+has chosen rightly to note as its characteristic, when he says,--
+
+    “That little Vernier, on whose slender lines
+    The midnight taper trembles as it shines,
+    Tells through the mist where dazzled Mercury burns,
+    And marks the point where Uranus returns.”
+
+But within a comparatively few years a new branch of astronomy has
+arisen, which studies sun, moon, and stars for what they are in
+themselves, and in relation to ourselves. Its study of the sun,
+beginning with its external features (and full of novelty and interest,
+even, as regards those), led to the further inquiry as to what it was
+made of, and then to finding the unexpected relations which it bore to
+the earth and our own daily lives on it, the conclusion being that, in
+a physical sense, it made us and re-creates us, as it were, daily, and
+that the knowledge of the intimate ties which unite man with it brings
+results of the most practical and important kind, which a generation
+ago were unguessed at.
+
+This new branch of inquiry is sometimes called Celestial Physics,
+sometimes Solar Physics, and is sometimes more rarely referred to as
+the New Astronomy. I will call it here by this title, and try to tell
+the reader something about it which may interest him, beginning with
+the sun.
+
+[Illustration: FIG. 1.--THE SUN’S SURROUNDINGS.]
+
+The whole of what we have to say about the sun and stars presupposes a
+knowledge of their size and distance, and we may take it for granted
+that the reader has at some time or another heard such statements as
+that the moon’s distance is two hundred and forty thousand miles, and
+the sun’s ninety-three million (and very probably has forgotten them
+again as of no practical concern). He will not be offered here the
+kind of statistics which he would expect in a college text-book; but
+we must linger a moment on the threshold of our subject--the nature of
+these bodies--to insist on the real meaning of such figures as those
+just quoted. We are accustomed to look on the sun and moon as far off
+together in the sky; and though we know the sun is greater, we are apt
+to think of them vaguely as things of a common order of largeness,
+away among the stars. It would be safe to say that though nine out of
+ten readers have learned that the sun is larger than the moon, and, in
+fact, larger than the earth itself, most of them do not at all realize
+that the difference is so enormous that if we could hollow out the
+sun’s globe and place the earth in the centre, there would still be so
+much room that the moon might go on moving in her present orbit at two
+hundred and forty thousand miles from the earth,--_all within the globe
+of the sun itself_,--and have plenty of room to spare.
+
+As to the distance of ninety-three million miles, a cannon-ball would
+travel it in about fifteen years. It may help us to remember that at
+the speed attained by the Limited Express on our railroads a train
+which had left the sun for the earth when the “Mayflower” sailed from
+Delftshaven with the Pilgrim Fathers, and which ran at that rate day
+and night, would in 1887 still be a journey of some years away from
+its terrestrial station. The fare at the customary rates, it may be
+remarked, would be rather over two million five hundred thousand
+dollars, so that it is clear that we should need both money and leisure
+for the journey.
+
+Perhaps the most striking illustration of the sun’s distance is
+given by expressing it in terms of what the physiologists would call
+velocity of nerve transmission. It has been found that sensation is not
+absolutely instantaneous, but that it occupies a very minute time in
+travelling along the nerves; so that if a child puts its finger into
+the candle, there is a certain almost inconceivably small space of
+time, say the one-hundredth of a second, before he feels the heat. In
+case, then, a child’s arm were long enough to touch the sun, it can be
+calculated from this known rate of transmission that the infant would
+have to live to be a man of over a hundred before it knew that its
+fingers were burned.
+
+Trying with the help of these still inadequate images, we may get some
+idea of the real size and distance of the sun. I could wish not to have
+to dwell upon such figures, that seem, however, indispensable; but we
+are now done with these, and are ready to turn to the telescope and see
+what the sun itself looks like.
+
+[Illustration: FIG. 2.--VIEW OF THE SUN ON SEPT. 20, 1870.]
+
+[Illustration: FIG. 3.--THE SUN ON SEPT. 22, 1870.
+
+(FROM A PHOTOGRAPH)]
+
+The sun, as we shall learn later, is a star, and not a particularly
+large star. It is, as has been said, “only a private in the host of
+heaven,” but it is one of that host; it is one of those glittering
+points to which we have been brought near. Let us keep in mind, then,
+from the first, what we shall see confirmed later, that there is an
+essentially similar constitution in them all, and not forget that when
+we study the sun, as we now begin to do, we are studying the stars also.
+
+If we were called on to give a description of the earth and all that
+is on it, it would be easily understood that the task was impossibly
+great, and that even an account of its most striking general features
+might fill volumes. So it is with the sun; and we shall find that
+in the description of the general character of its immediate surface
+alone, there is a great deal to be told. First, let us look at a little
+conventional representation (Fig. 1), as at a kind of outline of the
+unknown regions we are about to explore. The circle represents the
+Photosphere, which is simply what the word implies, that “sphere” of
+“light” which we have daily before our eyes, or which we can study
+with the telescope. Outside this there is a thin envelope, which rises
+here and there into irregular prominences, some orange-scarlet, some
+rose-pink. This is the Chromosphere, a thin shell, mainly of crimson
+and scarlet tints, invisible even to the telescope except at the time
+of a total eclipse, when alone its true colors are discernible, but
+seen as to its form at all times by the spectroscope. It is always
+there, not hidden in any way, and yet not seen, only because it is
+overpowered by the intenser brilliancy of the Photosphere, as a
+glow-worm’s shine would be if it were put beside an electric light.
+Outside all is the strange shape, which represents the mysterious
+Corona, seen by the naked eye in a total eclipse, but at all other
+times invisible even to telescope and spectroscope, and of whose true
+nature we are nearly ignorant from lack of opportunity to study it.
+
+[Illustration: FIG. 4.--THE SUN ON SEPT. 26, 1870.]
+
+Disregarding other details, let us carry in our minds the three main
+divisions,--the Photosphere, or daily visible surface of the sun, which
+contains nearly all its mass or substance; the Chromosphere; and the
+unsubstantial Corona, which is nevertheless larger than all the rest.
+We begin our examination with the Photosphere.
+
+There are records of spots having been seen with the naked eye before
+the invention of the telescope, but they were supposed to be planets
+passing between us and the surface; and the idea that the sun was pure
+fire, necessarily immaculate, was taught by the professors of the
+Aristotelian philosophy in mediæval schools, and regarded almost as
+an article of religious faith. We can hardly conceive, now, the shock
+of the first announcement that spots were to be found on the sun, but
+the notion partook in contemporary minds at once of the absurd and the
+impious; and we notice here, what we shall have occasion to notice
+again, that these physical discoveries from the first affect men’s
+thoughts in unexpected ways, and modify their scheme of the moral
+universe as well as of the physical one.
+
+[Illustration: FIG. 5.--SEPT. 19, 1870.]
+
+[Illustration: FIG. 6.--SEPT. 20, 1870.
+
+(ENGRAVED FROM A PHOTOGRAPH BY RUTHERFURD.)]
+
+Very little indeed was added to the early observations of Fabricius and
+Galileo until a time within the remembrance of many of us; for it is
+since the advent of the generation now on the stage that nine-tenths of
+the knowledge of the subject has been reached.
+
+Let us first take a general view of the sun, and afterward study it
+in detail. What we see with a good telescope in this general view is
+something like this. Opposite are three successive views (Figs. 2, 3,
+4) taken on three successive days,--quite authentic portraits, since
+the sun himself made them; they being, in fact, projected telescopic
+images which have been fixed for us by photography, and then exactly
+reproduced by the engraver. The first was taken (by Mr. Rutherfurd, of
+New York) on the 20th of September, 1870, when a remarkably large spot
+had come into view. It is seen here not far from the eastern edge (the
+left hand in the engraving), and numerous other spots are also visible.
+The reader should notice the position of these, and then on turning to
+the next view (Fig. 3, taken on September 22d) he will see that they
+have all shifted their places, by a common motion toward the west. The
+great spot on the left has now got well into view, and we can see its
+separate parts; the group which was on the left of the centre has got
+a little to the right of it, and so on. From the common motion of them
+all, we might suspect that the sun was turning round on an axis like
+the earth, carrying the spots with it; and as we continue to observe,
+this suspicion becomes certainty. In the third view (Fig. 4), taken on
+September 26th, the spot we first saw on the left has travelled more
+than half across the disk, while others we saw on September 20th have
+approached to the right-hand edge or passed wholly out of sight behind
+it. The sun does rotate, then, but in twenty-five or twenty-six of
+our days,--I say twenty-five _or_ twenty-six, because (what is very
+extraordinary) it does not turn all-of-a-piece like the earth, but some
+parts revolve faster than others,--not only faster in feet and inches,
+but in the number of turns,--just as though the rim of a carriage wheel
+were to make more revolutions in a mile than the spokes, and the spokes
+more than the hub. Of course no solid wheel could so turn without
+wrenching itself in pieces, but that the great solar wheel does, is
+incontestable; and this alone is a convincing proof that the sun’s
+surface is not solid, but liquid or gaseous.
+
+[Illustration: FIG. 7.--SEPT. 21, 1870.]
+
+[Illustration: FIG. 8.--SEPT. 22, 1870.]
+
+But let us return to the great spot which we saw coming round the
+eastern edge. Possibly the word “great” may seem misapplied to what was
+but the size of a pin-head in the first engraving, but we must remember
+that the disk of the sun there shown is in reality over 800,000 miles
+in diameter. We shall soon see whether this spot deserves to be called
+“great” or not.
+
+[Illustration: FIG. 9.--SEPT. 23, 1870.]
+
+[Illustration: FIG. 10.--SEPT. 26, 1870.]
+
+Next we have six enlarged views of it on the 19th, 20th, 21st, 22d,
+23d, and 26th. On the 19th it is seen very near the eastern limb,
+showing like a great hole in the sun, and foreshortened as it comes
+into view around the dark edge; for the edge of the sun is really
+darker than the central parts, as it is shown here, or as one may see
+even through a smoked glass by careful attention. On the 20th we have
+the edge still visible, but on the 21st the spot has advanced so far
+that the edge cannot be shown for want of room. We see distinctly
+the division of the spot into the outer shades which constitute the
+penumbra, and the inner darker ones which form the umbra and nucleus.
+We notice particularly in this enlarged view, by comparing the
+appearances on the 21st, 22d, and 23d, that the spot not only turns
+with the sun (as we have already learned), but moves and changes within
+itself in the most surprising way, like a terrestrial cloud, which
+not only revolves with the rest of the globe, but varies its shape
+from hour to hour. This is seen still more plainly when we compare
+the appearance on the 23d with that on the 26th, only three days
+later, where the process has begun by which the spot finally breaks
+up and forever disappears. On looking at all this, the tremendous
+scale on which the action occurs must be borne in mind. On the 21st,
+for instance, the umbra, or dark central hole, alone was large enough
+to let the whole globe of our own earth drop in without touching
+the sides! We shall have occasion to recur to this view of the 21st
+September again.
+
+[Illustration: FIG. 11.--NASMYTH’S WILLOW LEAVES. (FROM HERSCHEL’S
+“OUTLINES OF ASTRONOMY.”)]
+
+In looking at this spot and its striking changes, the reader must not
+omit to notice, also, a much less obvious feature,--the vaguely seen
+mottlings which show all over the sun’s surface, both quite away from
+the spots and also close to them, and which seem to merge into them.
+
+[Illustration: FIG. 12.--THE CACTUS TYPE. (FROM SECCHI’S “LE SOLEIL.”)]
+
+I think if we assign one year rather than another for the birth of the
+youthful science of solar physics, it should be 1861, when Kirchhoff
+and Bunsen published their memorable research on Spectrum Analysis,
+and when Nasmyth observed what he called the “willow-leaf” structure
+of the solar surface (see Fig. 11). Mr. Nasmyth, with a very powerful
+reflecting telescope, thought he had succeeded in finding what these
+faint mottlings really are composed of, and believed that he had
+discovered in them some most extraordinary things. This is what he
+thought he saw: The whole sun is, according to him, covered with huge
+bodies of most definite shape, that of the oblong willow leaf, and of
+enormous but uniform size; and the faint mottlings the reader has just
+noticed are, according to him, made up of these. “These,” he says,
+“cover the whole disk of the sun (except in the space occupied by the
+spots) in countless millions, and lie crossing each other in every
+imaginable direction.” Sir John Herschel took a particular interest
+in the supposed discovery, and, treating it as a matter of established
+fact, proceeded to make one of the most amazing suggestions in
+explanation that ever came from a scientific man of deserved eminence.
+We must remember how much there is unknown in the sun still, and what
+a great mystery even yet overhangs many of our relations to that body
+which maintains our own vital action, when we read the following words,
+which are Herschel’s own. Speaking of these supposed spindle-shaped
+monsters, he says:
+
+  “The exceedingly definite shape of these objects, their exact
+  similarity to one another, and the way in which they lie across
+  and athwart each other,--all these characters seem quite
+  repugnant to the notion of their being of a vaporous, a cloudy,
+  or a fluid nature. Nothing remains but to consider them as
+  separate and independent sheets, flakes, or scales, having some
+  sort of solidity. And these ... are evidently _the immediate
+  sources of the solar light and heat_, by whatever mechanism or
+  whatever processes they may be enabled to develop, and as it were
+  elaborate, these elements from the bosom of the non-luminous
+  fluid in which they appear to float. Looked at in this point of
+  view, we cannot refuse to regard them as _organisms_ of some
+  peculiar and amazing kind; and though it would be too daring to
+  speak of such organization as partaking of the nature of life,
+  yet we do know that vital action is competent to develop at once
+  heat and light and electricity.”
+
+[Illustration: FIG. 13.--EQUATORIAL TELESCOPE AND PROJECTION.]
+
+Such are his words; and when we consider that each of these solar
+inhabitants was supposed to extend about two hundred by one thousand
+miles upon the surface of the fiery ocean, we may subscribe to Mr.
+Proctor’s comment, that “Milton’s picture of him who on the fires of
+hell ‘lay floating many a rood,’ seems tame and commonplace compared
+with Herschel’s conception of these floating monsters, the least
+covering a greater space than the British Islands.”
+
+[Illustration: FIG. 14.--POLARIZING EYE-PIECE.]
+
+I hope I may not appear wanting in respect for Sir John Herschel--a man
+whose memory I reverence--in thus citing views which, if his honored
+life could have been prolonged, he would have abandoned. I do so
+because nothing else can so forcibly illustrate the field for wonder
+and wild conjecture solar physics presented even a few years ago; and
+its supposed connection with that “Vital Force,” which was till so
+lately accepted by physiology, serves as a kind of landmark on the way
+we have come.
+
+This new science of ours, then, youthful as it is, has already had its
+age of fable.
+
+After a time Nasmyth’s observation was attributed to imperfect
+definition, but was not fairly disproved. He had, indeed, a basis of
+fact for his statement, and to him belongs the credit of first pointing
+out the existence of this minute structure, though he mistook its true
+character. It will be seen later how the real forms might be mistaken
+for leaves, and _in certain particular cases_ they certainly do take on
+a very leaf-like appearance. Here is a drawing (Fig. 12) which Father
+Secchi gives of some of them in the spot of April 14, 1867, and which
+he compares to a branch of cactus. He remarks somewhere else that they
+resemble a crystallization of sal-ammoniac, and calls them veils of
+most intricate structure. This was the state of our knowledge in 1870,
+and it may seem surprising that such wonderful statements had not been
+proved or disproved, when they referred to mere matters of observation.
+But direct observation is here very difficult on account of the
+incessant tremor and vibration of our own atmosphere.
+
+[Illustration: FIG. 15.--SPOT OF SEPT. 21, 1870. (REDUCED FROM AN
+ORIGINAL DRAWING BY S. P. LANGLEY.)]
+
+[Illustration: FIG. 16.--SPOT OF MARCH 5, 1873. (REDUCED FROM AN
+ORIGINAL DRAWING BY S. P. LANGLEY.)]
+
+The surface of the sun may be compared to an elaborate engraving,
+filled with the closest and most delicate lines and hatchings, but an
+engraving which during ninety-nine hundredths of the time can only be
+seen across such a quivering mass of heated air as makes everything
+confused and liable to be mistaken, causing what is definite to look
+like a vaguely seen mottling. It is literally true that the more
+delicate features we are about to show, are only distinctly visible
+even by the best telescope during less than one-hundredth of the
+time, coming out as they do in brief instants when our dancing air is
+momentarily still, so that one who has sat at a powerful telescope all
+day is exceptionally lucky if he has secured enough glimpses of the
+true structure to aggregate five minutes of clear seeing, while at all
+other times the attempt to magnify only produces a blurring of the
+image. This study, then, demands not only fine telescopes and special
+optical aids, but endless patience.
+
+[Illustration: FIG. 17.--SUN ON MARCH 5, 1873. (FROM A DRAWING BY S. P.
+LANGLEY.)]
+
+My attention was first particularly directed to the subject in 1870
+(shortly after the regular study of the Photosphere was begun at the
+Allegheny Observatory by means of its equatorial telescope of thirteen
+inches’ aperture), with the view of finding out what this vaguely seen
+structure really is. Nearly three years of constant watching were given
+to obtain the results which follow. The method I have used for it is
+indicated in the drawing (Fig. 13), which shows the preliminary step
+of projecting the image of the sun directly upon a sheet of paper,
+divided into squares and attached to the eye-end of a great equatorial
+telescope. When this is directed to the sun in a darkened dome, the
+solar picture is formed upon the paper as in a camera obscura, and this
+picture can be made as large or as small as we please by varying the
+lenses which project it. As the sun moves along in the sky, its image
+moves across the paper; and as we can observe how long the whole sun
+(whose diameter in miles is known) takes to cross, we can find how many
+miles correspond to the time it is in crossing one of the squares, and
+so get the scale of the future drawing, and the true size in miles of
+the spot we are about to study. Then a piece of clock-work attached to
+the telescope is put in motion, and it begins to follow the sun in the
+sky, and the spot appears fixed on the paper. A tracing of the spot’s
+outline is next made, but the finer details are not to be observed by
+this method, which is purely preliminary, and only for the purpose
+of fixing the scale and the points of the compass (so to speak) on
+the sun’s face. The projecting apparatus is next removed and replaced
+by the polarizing eye-piece. Sir William Herschel used to avoid the
+blinding effects of the concentrated solar light by passing the rays
+through ink and water, but the phenomena of “polarization” have been
+used to better advantage in modern apparatus. This instrument, one
+of the first of its kind ever constructed, and in which the light is
+polarized with three successive reflections through the three tubes
+seen in the drawing (Fig. 14), was made in Pittsburgh as a part of the
+gift of apparatus by one of its citizens to the Observatory, and has
+been most useful. By its aid the eye can be safely placed where the
+concentrated heat would otherwise melt iron. In practice I have often
+gazed through it at the sun’s face without intermission from four to
+five hours, with no more fatigue or harm to the eye than in reading a
+book. By its aid the observer fills in the outline already projected on
+the paper.
+
+[Illustration: FIG. 18.--“THE PLUME” SPOT OF MARCH 5 AND 6, 1873. (FROM
+AN ORIGINAL DRAWING BY S. P. LANGLEY.)]
+
+The photograph has transported us already so near the sun’s surface
+that we have seen details there invisible to the naked eye. We have
+seen that what we have called “spots” are indeed regions whose actual
+vastness surpasses the vague immensity of a dream, and it will not
+cause surprise that in them is a temperature which also surpasses
+greatly that of the hottest furnace. We shall see later, in fact, that
+the whole surface is composed largely of metals turned into vapor in
+this heat, and that if we could indeed drop our great globe itself upon
+the sun, it would be dissipated as a snow-flake. Now, we cannot suppose
+this great space is fully described when we have divided it into the
+penumbra, umbra, and nucleus, or that the little photograph has shown
+us all there is, and we rather anticipate that these great spaces must
+be filled with curious things, if we could get near enough to see them.
+We cannot advantageously enlarge our photograph further; but if we
+could really come closer, we should have the nearer view that the work
+at Allegheny, I have just alluded to, now affords. The drawing (Fig.
+15) of the central part of the same great spot, already cited, was made
+on the 21st of September, 1870, and may be compared with the photograph
+of that day. We have now a greatly more magnified view than before, but
+it is not blurred by the magnifying, and is full of detail. We have
+been brought within two hundred thousand miles of the sun, or rather
+less than the actual distance of the moon, and are seeing for ourselves
+what was a few years since thought out of the reach of any observer.
+See how full of intricate forms that void, black, umbral space in
+the photograph has become! The penumbra is filled with detail of the
+strangest kind, and there are two great “bridges,” as they are called,
+which are almost wholly invisible in the photograph. Notice the line
+in one of the bridges which follows its sinuosities through its whole
+length of twelve thousand miles, making us suspect that it is made up
+of smaller parts as a rope is made up of cords (as, in fact, it is);
+and look at the end, where the cords themselves are unravelled into
+threads fine as threads of silk, and these again resolved into finer
+fibres, till in more and more web-like fineness it passes beyond the
+reach of sight! I am speaking, however, here rather of the wonderful
+original, as I so well remember it, than of what my sketch or even the
+engraver’s skill can render.
+
+[Illustration: FIG. 19.--TYPICAL SUN SPOT OF DECEMBER, 1873.
+
+(REDUCED FROM AN ORIGINAL DRAWING BY S. P. LANGLEY.)]
+
+[Illustration: FIG. 20.--FROST CRYSTAL.]
+
+Next we have quite another “spot” belonging to another year (1873).
+First, there is a view (Fig. 17) of the sun’s disk with the spot on
+it (as it would appear in a small telescope), to show its relative
+size, and then a larger drawing of the spot itself (Fig. 16), on a
+scale of twelve thousand miles to the inch, so that the region shown
+to the reader’s eyes, though but a “spot” on the sun, covers an area
+of over one billion square miles, or more than five times the entire
+surface of the earth, land, and water. To help us to conceive its
+vastness, I have drawn in one corner the continents of North and South
+America on the same scale as the “spot.” Notice the evidence of
+solar whirlwinds and the extraordinary “plume” (Fig. 16), which is a
+something we have no terrestrial simile for. The appearance of the
+original would have been described most correctly by such incongruous
+images as “leaf-like” and “crystalline” and “flame-like;” and even in
+this inadequate sketch there may remain some faint suggestion of the
+appearance of its wonderful archetype, which was indeed that of a great
+flame leaping into spires and viewed through a window covered with
+frost crystals. Neither “frost” nor “flame” is really there, but we
+cannot avoid this seemingly unnatural union of images, which was fully
+justified by the marvellous thing itself. The reader must bear in mind
+that the whole of this was actually in motion, not merely turning with
+the sun’s rotation, but whirling and shifting within itself, and that
+the motion was in parts occasionally probably as high as fifty miles
+per second,--per _second_, remember, not per hour,--so that it changed
+under the gazer’s eyes. The hook-shaped prominence in the lower part
+(actually larger than the United States) broke up and disappeared in
+about twenty minutes, or while the writer was engaged in drawing it.
+The imagination is confounded in an attempt to realize to itself the
+true character of such a phenomenon.
+
+[Illustration: FIG. 21.--CYCLONE SPOT. (DRAWN BY FATHER SECCHI.)]
+
+On page 19 is a separate view of the plume (Fig. 18), a fac-simile of
+the original sketch, which was made with the eye at the telescope. The
+pointed or flame-like tips are not a very common form, the terminals
+being more commonly clubbed, like those in Father Secchi’s “branch
+of cactus” type given on page 12. It must be borne in mind, too, if
+the drawing does not seem to contain all that the text implies, that
+there were but a few minutes in which to attempt to draw, where even a
+skilled draughtsman might have spent hours on the details momentarily
+visible, and that much must be left to memory. The writer’s note-book
+at the time contains an expression of despair at his utter inability to
+render most of what he saw.
+
+Let us now look at another and even more wonderful example. Fig. 19
+shows part of a great spot which the writer drew in December, 1873,
+when the rare coincidence happened of a fine spot and fine terrestrial
+weather to observe it in. In this, as well as in the preceding drawing,
+the pores which cover the sun’s surface by millions may be noted. The
+luminous dots which divide them are what Nasmyth imperfectly saw, but
+we are hardly more able than he to say what they really are. Each of
+these countless “dots” is larger than England, Scotland, and Ireland
+together! The wonderful “crystalline” structure in the centre cannot
+be a real crystal, for it is ten times the area of Europe, and changed
+slowly while I drew it; but the reader may be sure that its resemblance
+to some crystallizations has not been in the least exaggerated. I have
+sought to study various actual crystals for comparison, but found none
+quite satisfactory. That of sal-ammoniac in some remote way resembles
+it, as Secchi says; but perhaps the frost crystals on a window-pane
+are better. Fig. 20 shows one selected among several windows I had
+photographed in a preceding winter, which has some suggestions of the
+so-called crystalline spot-forms in it, but which lacks the filamentary
+thread-like components presently described. Of course the reader will
+understand that it is given as a suggestion of the appearance merely,
+and that no similarity of nature is meant to be indicated.
+
+[Illustration: FIG. 22.--SPOT OF MARCH 31, 1875. (FROM AN ORIGINAL
+DRAWING BY S. P. LANGLEY.)]
+
+There were wonderful fern-like forms in this spot, too, and an
+appearance like that of pine-boughs covered with snow; for, strangely
+enough, the intense whiteness of the solar surface in the best
+telescopes constantly suggests cold. I have had the same impression
+vividly in looking at the immense masses of molten-white iron in a
+great puddling-furnace. The salient feature here is one very difficult
+to see, even in good telescopes, but one which is of great interest. It
+has been shown in the previous drawings, but we have not enlarged on
+it. Everywhere in the spot are long white threads, or filaments, lying
+upon one another, tending in a general sense toward the centre, and
+each of which grows brighter toward its inner extremity. These make up,
+in fact, as we now see, the penumbra, or outer shade, and the so-called
+“crystal” is really affiliated to them. Besides this, on closer looking
+we see that the inner shade, or umbra, and the very deepest shades, or
+nuclei, are really made of them too. We can look into the dark centre,
+as into a funnel, to the depth of probably over five thousand miles;
+but as far as we may go down we come to no liquid or solid floor, and
+see only volumes of whirling vapor, disposed not vaguely like our
+clouds, but in the singularly definite, fern-like, flower-like forms
+which are themselves made of these “filaments,” each of which is from
+three to five thousand miles long, and from fifty to two hundred miles
+thick, and each of which (as we saw in the first spot) appears to be
+made up like a rope of still finer and finer strands, looking in the
+rare instants when irradiation makes an isolated one visible, like a
+thread of gossamer or the finest of cobweb. These suggest the fine
+threads of spun glass; and here there is something more than a mere
+resemblance of form, for both appear to have one causal feature in
+common, due to a viscous or “sticky” fluid; for there is much reason to
+believe that the solar atmosphere, even where thinner than our own air,
+is rendered viscous by the enormous heat, and owes to this its tendency
+to pull out in strings in common with such otherwise dissimilar things
+as honey, or melted sugar, or melted glass.
+
+We may compare those mysterious things, the filaments, to long grasses
+growing in the bed of a stream, which show us the direction and the
+eddies of the current. The likeness holds in more ways than one. They
+are not lying, as it were, flat upon the surface of the water, but
+_within_ the medium; and they do not stretch along in any one plane,
+but they bend down and up. Moreover, they are, as we see, apparently
+rooted at one end, and their tips rise above the turbid fluid and grow
+brighter as they are lifted out of it. But perhaps the most significant
+use of the comparison is made if we ask whether the stream is moving in
+an eddy like a whirlpool or boiling up from the ground. The question
+in other words is, “Are these spots themselves the sign of a mere
+chaotic disturbance, or do they show us by the disposition of these
+filaments that each is a great solar maelstrom, carrying the surface
+matter of the sun down into its body? or, finally, are they just the
+opposite,--something comparable to fiery fountains or volcanoes on the
+earth, throwing up to the surface the contents of the unknown solar
+interior?”
+
+[Illustration: FIG. 23.--CIRROUS CLOUD. (FROM A PHOTOGRAPH.)]
+
+Before we try to answer this question, let us remember that the
+astonishing rapidity with which these forms change, and still more the
+fact that they do not by any means always change by a bodily removal
+of one part from another, but by a dissolving away and a fading out
+into invisibility, like the melting of a cloud into thin air,--let us
+remember that all this assimilates them to something cloud-like and
+vaporous, rather than crystalline, and that, as we have here seen,
+we can ourselves pronounce from such results of recent observation
+that these are not lumps of scoriæ floating on the solar furnace (as
+some have thought them), and still less, literal crystals. We can see
+for ourselves, I believe, that so far there is no evidence here of
+any solid, or even liquid, but that the surface of the sun is purely
+vaporous. Fig. 23 shows a cirrous cloud in our own atmosphere, caught
+for us by photography, and which the reader will find it interesting to
+compare with the apparently analogous solar cloud-forms.
+
+[Illustration: FIG. 24.--SPOT OF MARCH 31, 1875. (FROM AN ORIGINAL
+DRAWING BY S. P. LANGLEY.)]
+
+“Vaporous,” we call them, for want of a better word, but without
+meaning that it is like the vapor of our clouds. There is no exact
+terrestrial analogy for these extraordinary forms, which are in fact,
+as we shall see later, composed of iron and other metals--not of solid
+iron nor even of liquid, but iron heated beyond even the liquid state
+to that of iron-steam or vapor.
+
+With all this in mind, let us return to the question, “Are the spots,
+these gigantic areas of disturbance, comparable to whirlpools or to
+volcanoes?” It may seem unphilosophical to assume that they are one
+or the other, and in fact they may possibly be neither; but it is
+certain that the surface of the sun would soon cool from its enormous
+temperature, if it were not supplied with fresh heat, and it is almost
+certain that this heat is drawn from the interior. As M. Faye has
+pointed out,[1] there _must_ be a circulation up and down, the cooled
+products being carried within, heated and brought out again, or the
+sun would, however hot, grow cold outside; and, what is of interest
+to us, the earth would grow cold also, and we should all die. No one,
+I believe, who has studied the subject, will contradict the statement
+that if the sun’s surface were absolutely cut off from any heat supply
+from the interior, organic life in general upon the earth (and our
+own life in particular) would cease much within a month. This solar
+circulation, then, is of nearly as much consequence to us as that of
+our own bodies, if we but knew it; and now let us look at the spots
+again with this in mind.
+
+    [1] To Mr. Herbert Spencer must be assigned the earliest
+        suggestion of the necessity of such a circulation.
+
+[Illustration: FIG. 25.--TYPICAL ILLUSTRATION OF FAYE’S THEORY.]
+
+Fig. 21 shows a drawing by Father Secchi of a spot in 1854; and it is,
+if unexaggerated, quite the most remarkable case of distinct cyclonic
+action recorded. I say “if unexaggerated” because there is a strong
+tendency in most designers to select what is striking in a spot, and
+to emphasize that unduly, even when there is no conscious disposition
+to alter. Every one who sketches may see a similar unconscious
+tendency in himself or herself, shown in a disposition to draw all the
+mountains and hills too high,--a tendency on which Ruskin, I think,
+has remarked. In drawings of the sun there is a strong temptation to
+exaggerate these circular forms, and we must not forget this in making
+up the evidence. There is great need of caution, then, in receiving
+such representations; but there certainly are forms which seem to be
+clearly due to cyclonic action. They are usually scattered, however,
+through larger spots, and I have never, in all my study of the sun,
+seen one such complete type of the cyclone spot as that first given
+from Secchi. Instances where spots break up into numerous subdivisions
+by a process of “segmentation” under the apparent action of separate
+whirlwinds are much more common. I have noticed, as an apparent effect
+of this segmentation, what I may call the “honeycomb structure” from
+its appearance with low powers, but which with higher ones turns out to
+be made up of filamentary masses disposed in circular and ovoid curves,
+often apparently overlying one another, and frequently presenting a
+most curious resemblance to vegetable forms, though we appear to see
+the real agency of whirlwinds in making them. I add some transcripts
+of my original pencil memoranda themselves, made with the eye at the
+telescope, which, though not at all finished drawings, may be trusted
+the more as being quite literal transcripts at first hand.
+
+[Illustration: FIG. 26.--SPOT OF OCT. 13, 1876. (FROM ORIGINAL DRAWING
+BY S. P. LANGLEY.)]
+
+Figs. 22 and 24, for instance, are two sketches of a little spot,
+showing what, with low powers, gives the appearance I have called the
+honeycomb structure, but which we see here to be due to whirls which
+have disposed the filaments in these remarkable forms. The first was
+drawn at eleven in the forenoon of March 31, 1875, the second at
+three in the afternoon of the same day. The scale of the drawing is
+fifteen thousand miles to the inch, and the changes in this little
+spot in these few hours imply a cataclysm compared with which the
+disappearance of the American continent from the earth’s surface would
+be a trifle.
+
+The very act of the solar whirlwind’s motion seemed to pass before my
+eyes in some of these sketches; for while drawing them as rapidly as
+possible, a new hole would be formed where there was none before, as if
+by a gigantic invisible auger boring downward.
+
+[Illustration: FIG. 27.--PHOTOGRAPH OF EDGE OF SUN. (BY PERMISSION OF
+WARREN DE LA RUE, LONDON.)]
+
+M. Faye, the distinguished French astronomer, believes that, owing to
+the fact that different zones of the sun rotate faster than others,
+whirlwinds analogous to our terrestrial cyclones, but on a vaster
+scale, are set in motion, and suck down the cooled vapors of the solar
+surface into its interior, to be heated and returned again, thus
+establishing a circulation which keeps the surface from cooling down.
+He points out that we should not conclude that these whirlwinds are not
+acting everywhere, merely because our bird’s-eye view does not always
+show them. We see that the spinning action of a whirlpool in water
+becomes more marked as we go below the surface, which is comparatively
+undisturbed, and we often see one whirl break up into several minor
+ones, but all sucking downward and never upward. According to M. Faye,
+something very like this takes place on the sun, and in Fig. 25 he
+gives this section to show what he believes to occur in the case of a
+spot which has “segmented,” or divided into two, like the one whose
+(imaginary) section is shown above it. This theory is to be considered
+in connection with such drawings as we have just shown, which are
+themselves, however, no way dependent on theory, but transcripts from
+Nature.
+
+I do not here either espouse or oppose the “cyclonic” theory, but it is
+hardly possible for any one who has been an eyewitness of such things
+to refuse to regard some such disturbance as a real and efficient cause
+in such instances as this.
+
+Fig. 26, on nearly the same scale as the last, shows a spot which was
+seen on Oct. 13, 1876. It looked at first, in the telescope, like two
+spots without any connection; then, as vision improved and higher
+powers were employed, the two were seen to have a subtle bond of union,
+and each to be filled with the most curious foliage-forms, which I
+could only indicate in the few moments that the good definition lasted.
+The reader may be sure, I think, that there is no exaggeration of the
+curious shapes of the original; for I have been so anxious to avoid the
+overstatement of curvature that the error is more likely to be in the
+opposite direction.
+
+We must conclude that the question as to the cyclonic hypothesis cannot
+yet be decided, though the probabilities from telescopic evidence
+at present seem to me on the whole in favor of M. Faye’s remarkable
+theory, which has the great additional attraction to the student that
+it unites and explains numerous other quite disconnected facts.
+
+Turning now to the other solar features, let us once more consider
+the sun as a whole. Fig. 27 is a photograph taken from a part of the
+sun near its edge. We notice on it, what we see on every careful
+delineation of the sun, that its general surface is not uniformly
+bright, but that it grows darker as we approach the edge, where it
+is marked by whiter mottlings called faculæ, “something in the sun
+brighter than the sun itself,” and looking in the enlarged view which
+we present of one of them (Fig. 28), as if the surface of partly
+cooled metal in a caldron had been broken into fissures showing the
+brighter glow beneath. These “faculæ,” however, are really above the
+solar surface, not below it, and what we wish to direct particular
+attention to is that darkening toward the edge which makes them visible.
+
+[Illustration: FIG. 28.--FACULA. (FROM A DRAWING BY CHACORNAC.)]
+
+This is very significant, but its full meaning may not at first be
+clear. It is owing to an atmosphere which surrounds the sun, as the
+air does the earth. When we look horizontally through our own air, as
+at sunrise and sunset, we gaze through greater thicknesses of it than
+when we turn our eyes to the zenith. So when we look at the edge of
+the sun, the line of sight passes through greater depths of this solar
+atmosphere, and it dims the light shining behind it more than at the
+centre, where it is thin.
+
+This darkening toward the edge, then, means that the sun has an
+atmosphere which tempers its heat to us. Whatever the sun’s heat
+supply is within its globe, if this atmosphere grow thicker, the
+heat is more confined within, and our earth will grow colder; if the
+solar atmosphere grow thinner, the sun’s energy will be expended more
+rapidly, and our earth will grow hotter. This atmosphere, then, is in
+considerable part, at least, the subject of the action of the spots;
+this is what they are supposed to carry down or to spout up.
+
+We shall return to the study of it again; but what I want to point out
+now is that the temperature of the earth, and even the existence of man
+upon it, depends very much upon this, at first sight, insignificant
+phenomenon. What, then, is the solar atmosphere? Is it a permanent
+thing? Not at all. It is more light and unsubstantial than our own
+air, and is being whirled about by solar winds as ours toss the dust
+of the streets. It is being sucked down within the body of the sun by
+some action we do not clearly understand, and returned to the surface
+by some counter effect which we comprehend no better; and upon this
+imperfectly understood exchange depends in some way our own safety.
+
+There used to be recorded in medical books the case of a boy who, to
+represent Phœbus in a Roman mask, was gilded all over to produce the
+effect of the golden-rayed god, but who died in a few hours because,
+all the pores of the skin being closed by the gold-leaf, the natural
+circulation was arrested. We can count with the telescope millions of
+pores upon the sun’s surface, which are in some way connected with the
+interchange which has just been spoken of; and if this, his own natural
+circulation, were arrested or notably diminished, we should see his
+face grow cold, and know that our own health, with the life of all the
+human race, was waiting on his recovery.
+
+
+
+
+II.
+
+THE SUN’S SURROUNDINGS.
+
+
+As I write this, the fields glitter with snow-crystals in the winter
+noon, and the eye is dazzled with a reflection of the splendor which
+the sun pours so fully into every nook that by it alone we appear to
+see everything.
+
+Yet, as the day declines, and the glow of the sunset spreads up to the
+zenith, there comes out in it the white-shining evening star, which
+not the light, but the darkness, makes visible; and as the last ruddy
+twilight fades, not only this neighbor-world, whose light is fed from
+the sunken sun, but other stars appear, themselves self-shining suns,
+which were above us all through the day, unseen because of the very
+light.
+
+As night draws on, we may see the occasional flash of a shooting-star,
+or perhaps the auroral streamers spreading over the heavens; and
+remembering that these will fade as the sun rises, and that the nearer
+they are to it the more completely they will be blotted out, we infer
+that if the sun were surrounded by a halo of only similar brightness,
+this would remain forever invisible,--unless, indeed, there were
+some way of cutting off the light from the sun without obscuring its
+surroundings. But if we try the experiment of holding up a screen which
+just conceals the sun, nothing new is seen in its vicinity, for we are
+also lighted by the neighboring sky, which is so dazzlingly bright with
+reflected light as effectually to hide anything which may be behind it,
+so that to get rid of this glare we should need to hang up a screen
+_outside_ the earth’s atmosphere altogether.
+
+[Illustration: FIG. 29.--LUNAR CONE SHADOW.]
+
+Nature hangs such a screen in front of the earth when the moon passes
+between it and the sun; but as the moon is far too small to screen
+all the earth completely, and as so limited a portion of its surface
+is in complete shadow that the chances are much against any given
+individual’s being on the single spot covered by it, many centuries
+usually elapse before such a _total_ eclipse occurs at any given point;
+while yet almost every year there may be a partial eclipse, when, over
+a great portion of the earth at once, people may be able to look round
+the moon’s edge and see the sunlight but partly cut off. Nearly every
+one, then, has seen a partial eclipse of the sun, but comparatively few
+a total one, which is quite another thing, and worth a journey round
+the world to behold; for such a nimbus, or glory, as we have suggested
+the possibility of, does actually exist about the sun, and becomes
+visible to the naked eye on the rare occasions when it is visible at
+all, accompanied by phenomena which are unique among celestial wonders.
+
+The “corona,” as this solar crown is called, is seen during a total
+eclipse to consist of a bright inner light next the invisible sun,
+which melts into a fainter and immensely extended radiance (the writer
+has followed the latter to the distance of about ten million miles),
+and all this inner corona is filled with curious detail. All this is
+to be distinguished from another remarkable feature seen at the same
+time; for close to the black body of the moon are prominences of a
+vivid crimson and scarlet, rising up like mountains from the hidden
+solar disk, and these, which will be considered later, are quite
+distinct from the corona, though seen on the background of its pearly
+light.
+
+To understand what the lunar screen is doing for us, we may imagine
+ourselves at some station outside the earth, whence we should behold
+the moon’s shadow somewhat as in Fig. 29, where we must remember that
+since the lunar orbit is not a circle, but nearly an ellipse, the
+moon is at some times farther from the earth than at others. Here the
+extremity of its shadow is represented as just touching the surface of
+the globe, while it is evident that if the moon were at its greatest
+distance, its shadow might come to a point before reaching the earth at
+all. We speak, of course, only of the central cone of shade; for there
+is an outer one, indicated by the faint dotted lines, within whose much
+more extended limits the eclipse is partial, but with the latter we
+have at present nothing to do. The figure however, for want of room,
+is made to represent the proportions incorrectly, the real ones of the
+shadow being actually something like those of a sewing-needle,--this
+very long attenuated shadow sometimes, as we have just said, not
+reaching the earth at all, and when it does reach it, covering at the
+most a very small region indeed. Where this point touches, and wherever
+it rests, we should, in looking down from our celestial station, see
+that part of the earth in complete shadow, appearing like a minute dark
+spot, whose lesser diameter is seldom over a hundred and fifty miles.
+
+The eclipse is total only to those inhabitants of the earth within
+the track of this dark spot, though the spot itself travels across
+the earth with the speed of the moon in the sky; so that if it could
+leave a mark, it would in a few hours trace a dark line across the
+globe, looking like a narrow black tape curving across the side of the
+world next the sun. In Fig. 30, for instance, is the central track of
+the eclipse of July 29, 1878, as it would be visible to our celestial
+observer, beginning in Alaska in the forenoon, and ending in the Gulf
+of Mexico, which it reached in the afternoon. To those on the earth’s
+surface within this shadow it covered everything in view, and, for
+anything those involved in it could see, it was all-embracing and
+terrible, and worthily described in such lines as Milton’s,--
+
+                    “As when the sun ...
+    In dim eclipse, disastrous twilight sheds
+    On half the nations, and with fear of change
+    Perplexes monarchs.”
+
+We may enjoy the poet’s vision; but here, while we look down on
+the whole earth at once, we must admit that the actual area of the
+“twilight” is very small indeed. Within this area, however, the
+spectacle is one of which, though the man of science may prosaically
+state the facts, perhaps only the poet could render the impression.
+
+We can faintly picture, perhaps, how it would seem, from a station
+near the lunar orbit, to see the moon--a moving world--rush by with a
+velocity greater than that of the cannon-ball in its swiftest flight;
+but with equal speed its shadow actually travels along the earth. And
+now, if we return from our imaginary station to a real one here below,
+we are better prepared to see why this flying shadow is such a unique
+spectacle; for, small as it may be when seen in relation to the whole
+globe, it is immense to the observer, whose entire horizon is filled
+with it, and who sees the actual velocity of one of the heavenly
+bodies, as it were, brought down to him.
+
+The reader who has ever ascended to the Superga, at Turin, will recall
+the magnificent view, and be able to understand the good fortune of
+an observer (Forbes) who once had the opportunity to witness thence
+this phenomenon, and under a nearly cloudless sky. “I perceived,” he
+says, “in the southwest a black shadow like that of a storm about to
+break, which obscured the Alps. It was the lunar shadow coming toward
+us.” And he speaks of the “stupefaction”--it is his word--caused by
+the spectacle. “I confess,” he continues, “it was the most terrifying
+sight I ever saw. As always happens in the cases of sudden, silent,
+unexpected movements, the spectator confounds real and relative motion.
+I felt almost giddy for a moment, as though the massive building under
+me bowed on the side of the coming eclipse.” Another witness, who had
+been looking at some bright clouds just before, says: “The bright cloud
+I saw distinctly put out like a candle. The rapidity of the shadow, and
+the intensity, produced a feeling that something material was sweeping
+over the earth at a speed perfectly frightful. I involuntarily listened
+for the rushing noise of a mighty wind.”
+
+[Illustration: FIG. 30--TRACK OF LUNAR SHADOW.]
+
+Each one notes something different from another at such a time; and
+though the reader will find minute descriptions of the phenomena
+already in print, it will perhaps be more interesting if, instead of
+citations from books, I invite him to view them with me, since each can
+tell best what he has personally seen.
+
+[Illustration: FIG. 31.--INNER CORONA ECLIPSE OF 1869. FROM SHELBYVILLE
+PHOTOGRAPH. (ROYAL ASTRONOMICAL SOCIETY’S MEMOIRS.)]
+
+I have witnessed three total eclipses, but I do not find that
+repetition dulls the interest. The first was that of 1869, which
+passed across the United States and was nearly central over Louisville.
+My station was on the southern border of the eclipse track, not very
+far from the Mammoth Cave in Kentucky, and I well remember that
+early experience. The special observations of precision in which I
+was engaged would not interest the reader; but while trying to give
+my undivided attention to these, a mental photograph of the whole
+spectacle seemed to be taking without my volition. First, the black
+body of the moon advanced slowly on the sun, as we have all seen it do
+in partial eclipses, without anything noticeable appearing; nor till
+the sun was very nearly covered did the light of day about us seem
+much diminished. But when the sun’s face was reduced to a very narrow
+crescent, the change was sudden and startling, for the light which fell
+on us not only dwindled rapidly, but became of a kind unknown before,
+so that a pallid appearance overspread the face of the earth with an
+ugly livid hue; and as this strange wanness increased, a cold seemed to
+come with it. The impression was of something _unnatural_; but there
+was only a moment to note it, for the sun went out as suddenly as a
+blown-out gas-jet, and I became as suddenly aware that all around,
+where it had been, there had been growing into vision a kind of ghostly
+radiance, composed of separate pearly beams, looking distinct each from
+each, as though the black circle where the sun once was, bristled with
+pale streamers, stretching far away from it in a sort of crown.
+
+This was the mysterious corona, only seen during the brief moments
+while the shadow is flying overhead; but as I am undertaking to recall
+faithfully the impressions of the instant, I may admit that I was at
+the time equally struck with a circumstance that may appear trivial
+in description,--the extraordinary globular appearance of the moon
+herself. We all know well enough that the moon is a solid sphere, but
+it commonly _looks_ like a bright, flat circle fastened to the concave
+of the starry vault; and now, owing to its unwonted illumination, the
+actual rotundity was seen for the first time, and the result was to
+show it as it really is,--a monstrous, solid globe, suspended by some
+invisible support above the earth, with nothing apparent to keep it
+from tumbling on us, looking at the moment very near, and more than
+anything else like a gigantic black cannon-ball, hung by some miracle
+in the air above the neighboring cornfield. But in a few seconds all
+was over; the sunlight flashed from one point of the moon’s edge and
+then another, almost simultaneously, like suddenly kindled electric
+lights, which as instantly flowed into one, and it was day again.
+
+[Illustration: FIG. 32.--SKETCH OF OUTER CORONA, 1869. (U. S. COAST
+SURVEY REPORT.)]
+
+I have spoken of the “unnatural” appearance of the light just before
+totality. This is not due to excited fancy, for there is something
+so essentially different from the natural darkness of twilight, that
+the brute creation shares the feeling with us. Arago, for instance,
+mentions that in the eclipse of 1842, at Perpignan, where he was
+stationed, a dog which had been kept from food twenty-four hours was,
+to test this, thrown some bread just before “totality” began. The
+dog seized the loaf, began to devour it ravenously, and then, as the
+appearance already described came on, he dropped it. The darkness
+lasted some minutes, but not till the sun came forth again did the poor
+creature return to the food. It is no wonder, then, that men also,
+whether educated or ignorant, do not escape the impression. A party of
+the courtiers of Louis XV. is said to have gathered round Cassini to
+witness an eclipse from the terrace of the Paris observatory, and to
+have been laughing at the populace, whose cries were heard as the light
+began to fade; when, as the unnatural gloom came quickly on, a sudden
+silence fell on them too, the panic terror striking through their
+laughter. Something common to man and the brute speaks at such times,
+if never before or again; something which is not altogether physical
+apprehension, but more like the moral dismay when the shock of an
+earthquake is felt for the first time, and we first know that startling
+doubt, superior to reason, whether the solid frame of earth is real,
+and not “baseless as the fabric of a vision.”
+
+But this is appealing for illustration to an experience which most
+readers have doubtless been spared,[2] and I would rather cite the
+lighter one of our central party that day, a few miles north of me,
+at Shelbyville. In this part of Kentucky the colored population was
+large, and (in those days) ignorant of everything outside the life of
+the plantation, from which they had only lately been emancipated. On
+that eventful 8th of August they came in great numbers to view the
+enclosure and the tents of the observing party, and to inquire the
+price of the show. On learning that they might see it without charge
+from the outside, a most unfavorable opinion was created among them as
+to the probable merits of so cheap a spectacle, and they crowded the
+trees about the camp, shouting to each other sarcastic comments on the
+inferior interest of the entertainment. “Those trees there,” said one
+of the observers to me the next day, “were black with them, and they
+kept up their noise till near the last, when they suddenly stopped, and
+all at once, and as ‘totality’ came, we heard a wail and a noise of
+tumbling, as though the trees had been shaken of their fruit, and then
+the boldest did not feel safe till he was under his own bed in his own
+cabin.”
+
+    [2] This was written before the “Charleston earthquake”
+        occurred.
+
+[Illustration: FIG. 33.--TACCHINI’S DRAWING OF CORONA OF 1870.
+
+(SECCHI’S “LE SOLEIL.”)]
+
+It is impossible to give an exact view of what our friends at
+Shelbyville saw, for no drawings made there appear to have been
+preserved, and photography at that time could only indicate feebly
+the portion of the corona near the sun where it is brightest. Fig.
+31 is a fac-simile of one of the photographs taken on the occasion,
+which is interesting perhaps as one of the early attempts in this
+direction, for comparison with later ones; but as a picture it is very
+disappointing, for the whole structure of the outer corona we have
+alluded to is missed altogether, the plate having taken no impression
+of it.
+
+A drawing (Fig. 32) made by another observer, Mr. M’Leod, at
+Springfield, represents more of the outer structure; but the reader
+must remember that all drawings must, in the nature of the case (since
+there are but two or three minutes to sketch in), be incomplete,
+whatever the artist’s skill.
+
+[Illustration: FIG. 34.--WATSON’S NAKED-EYE DRAWING OF CORONA OF 1870.
+(U. S. COAST SURVEY REPORT.)]
+
+Up to this time it was still doubtful, not only what the corona
+was, but where it was; whether it was a something about the sun or
+moon, or whether, indeed, it might not be in our own atmosphere. The
+spectroscopic observations of Professors Young and Harkness at this
+same eclipse of a green line in its spectrum, due to some glowing
+gas, showed conclusively that it was largely, at any rate, a solar
+appendage, and partly, at least, self-luminous; and these and other
+results having awakened general discussion among astronomers in Europe
+as well as at home, the United States Government sent an expedition,
+under the direction of the late Professor Pierce, to observe an eclipse
+which in the next year, on Dec. 8, 1870, was total in the south of
+Spain. There were three parties; and of the most western of these,
+which was at Xeres under the charge of Professor Winlock, I was a
+member.
+
+[Illustration: FIG. 35.--PHOTOGRAPH SHOWING COMMENCEMENT OF OUTER
+CORONA.
+
+(ROYAL ASTRONOMICAL SOCIETY’S MEMOIRS.)]
+
+The duration of totality was known beforehand. It would last two
+minutes and ten seconds, and to secure what could be seen in this brief
+interval we crossed the ocean. Our station was in the midst of the
+sherry district, and a part of the instruments were in an orange-grove,
+where the ground was covered with the ripe fallen fruit, while the
+olive and vine about us in December reminded us of the distance we had
+come to gather the results of so brief an opportunity.
+
+To prepare for it, we had all arrived on the ground some weeks
+beforehand, and had been assiduously busy in installing the
+apparatus in the observing camp, which suggested that of a small
+army, the numerous instruments, some of them of considerable
+size,--equatorials, photographic apparatus, polariscopes, photometers,
+and spectroscopes,--being under tents, the fronts of which could be
+lifted when the time came for action.
+
+To the equatorial telescopes photographic cameras are attached instead
+of the eye-pieces, in the hope that the corona may be made to impress
+itself on the plate instead of on the eye. The eye is an admirable
+instrument itself, no doubt; but behind it is a brain, perhaps
+overwrought with excitement, and responding too completely to the
+nervous tension which most of us experience when those critical moments
+are passing so rapidly. The camera can see far less of the corona than
+the man, _but it has no nerves_, and what it sets down we may rely on.
+
+At such a time each observer has some particular task assigned to
+him, on which, if wise, he has drilled himself for weeks beforehand,
+so that no hesitation or doubt may arise in the moment of action; and
+his attention is expected to be devoted to this duty alone, which may
+keep him from noting any of the features which make the occasion so
+impressive as a spectacle. Most of my own particular work was again of
+a kind which would not interest the reader.
+
+Apart from this, I can recall little but the sort of pain of
+expectation, as the moment approached, till within a minute before
+totality the hum of voices around ceased, and an utter and most
+impressive silence succeeded, broken only by a low “Ah!” from the group
+without the camp, when the moment came. I remember that the clouds,
+which had hung over the sun while the moon was first advancing on its
+body, cleared away before the instant of totality, so that the last
+thing I saw was a range of mountains to the eastward still bright
+in the light; then, the next moment, the shadow rushed overhead and
+blotted out the distant hills, almost before I could turn my face to
+the instrument before me.
+
+[Illustration: FIG. 36.--ECLIPSE OF 1857, DRAWING BY LIAIS. (ROYAL
+ASTRONOMICAL SOCIETY’S MEMOIRS.)]
+
+The corona appeared to me a different thing from what it did the year
+before. It was apparently confined to a pearly light of a roughly
+quadrangular shape, close to the limb of the sun, broken by dark rifts
+(one of which was a conspicuous object); while within, and close to
+the limb, was what looked like a mountain rising from the hidden sun,
+of the color of the richest tint we should see in a rose-leaf held up
+against the light, while others were visible of an orange-scarlet.
+After a short scrutiny I turned to my task of analyzing the nature of
+the white light.
+
+The seconds fled, the light broke out again, and so did the hubbub
+of voices,--it was all over, and what had been missed then could not
+be recovered. The sense of self-reproach for wasted opportunity is
+a common enough feeling at this time, though one may have done his
+best, so little it seems to each he has accomplished; but when all the
+results had been brought together, we found that the spectroscopes,
+cameras, and polariscopes had each done their work, and the journey had
+not been taken in vain. In one point only we all differed, and this
+was about the direct ocular evidence, for each seemed to have seen a
+different corona, and the drawings of it were singularly unlike. Here
+are two (Figs. 33 and 34) taken at this eclipse at the same time,
+and from neighboring stations, by two most experienced astronomers,
+Tacchini and Watson. No one could guess that they represented the same
+object, and a similar discrepancy was common.
+
+[Illustration: FIG. 37.--ENLARGEMENT OF PART OF FIG. 38.]
+
+Considering that these were trained experts, whose special task it
+was, in this case, to draw the corona, which therefore claimed their
+undivided attention, I hardly know a more striking instance of the
+fallibility of human testimony. The evidence of several observers,
+however, pointed to the fact that the light really was more nearly
+confined to the part next the sun than the year before, so that the
+corona had probably changed during that interval, and grown smaller,
+which was remarkable enough. The evidence of the polariscope, on the
+whole, showed it to be partly due to reflected sunlight, while the
+spectroscope in the hands of Professor Young confirmed the last year’s
+observation, that it was also, and largely, self-luminous. Finally,
+the photographs, taken at very distant stations, showed the same dark
+rifts in the same place, and thus brought confirmatory evidence that
+it was not a local phenomenon in our own atmosphere. A photograph of
+it, taken by Mr. Brothers in Sicily, is the subject of the annexed
+illustration (Fig. 35), in which the very bright lights which, owing to
+“photographic irradiation,” seem to indent the moon, are chiefly due to
+the colored flames I have spoken of, which will be described later.
+
+It may be observed that the photographs taken in the next year (1871)
+were still more successful, and began to show still more of the
+structure, whose curious forms, resembling large petals, had already
+been figured by Liais. His drawing (Fig. 36), made in 1857, was
+supposed to be rather a fanciful sketch than a trustworthy one; but, as
+it will be seen, the photograph goes far to justify it.
+
+Figures 37 and 38 are copies published by Mr. Ranyard of the excellent
+photographs obtained in 1871, which are perhaps as good as anything
+done since, though even these do not show the outer corona. The first
+is an enlargement of a small portion of the detail in the second. It is
+scarcely possible for wood-engraving to reproduce the delicate texture
+of the original.
+
+[Illustration: FIG. 38.--FAC-SIMILE OF PHOTOGRAPH OF CORONA OF 1871.
+
+(ROYAL ASTRONOMICAL SOCIETY’S MEMOIRS.)]
+
+The years brought round the eclipse of 1878, which was again in United
+States territory, the central track (as Fig. 30 has already shown)
+running directly over one of the loftiest mountains of the country,
+Pike’s Peak, in Colorado. Pike’s Peak, though over fourteen thousand
+feet high, is often ascended by pleasure tourists; but it is one thing
+to stay there for an hour or two, and another to take up one’s abode
+there and get acclimated,--for to do the latter we must first pass
+through the horrors (not too strong a word) of mountain-sickness.
+This reaches its height usually on the second or third day, and is
+something like violent sea-sickness, complicated with the sensations
+a mouse may be supposed to have under the bell of an air-pump. After
+a week the strong begin to get over it, but none but the very robust
+should take its chances, as we did, without preparation; for on the
+night before the eclipse the life of one of our little party was
+pronounced in danger, and he was carried down in a litter to a cabin at
+an altitude of about ten thousand feet, where he recovered so speedily
+as to be able to do good service on the following day. The summit
+of the “Peak” is covered with great angular bowlders of splintered
+granite, among which we laid logs brought up for firewood, and on
+these, sacks of damp hay, then stretching a little tent over all and
+tying it down with wire to the rocks, we were fain to turn in under
+damp blankets, and to lie awake with incessant headache, drawing long,
+struggling breaths in the vain attempt to get air, and wondering how
+long the tent would last, as the canvas flapped and roared with a noise
+like that of a loose sail in a gale at sea, with occasional intervals
+of a dead silence, usually followed by a gust that shoved against the
+tent with the push of a solid body, and if a sleepers shoulders touched
+the canvas, shouldered him over in his bed. The stout canvas held, but
+the snow entered with the wind and lay in a deep drift on the pillow,
+when I woke after a brief sleep toward morning, and, looking out on the
+gray dawn, found that the snow had turned to hail, which was rattling
+sharply on the rocks with an accompaniment of thunder, which seemed to
+roll from all parts of the horizon. The snow lay thick, and the sheets
+of hail were like a wall, shutting out the sight of everything a few
+rods off, and this was in July! I thought of my December station in
+sunny Andalusia.
+
+[Illustration: FIG. 39.--“SPECTRES.”]
+
+Hail, rain, sleet, snow, fog, and every form of bad weather continued
+for a week on the summit, while it was almost always clear below.
+It was often a remarkable sight to go to the edge and look down. The
+expanse of “the plains,” which stretched eastward to a horizon line
+over a hundred miles distant, would be in bright sunshine beneath,
+while the hail was all around and above us; and the light coming _up_
+instead of down gave singular effects when the clouds parted below, the
+plains seeming at such times to be opalescent with luminous yellow and
+green, as though the lower world were translucent, and the sun were
+beneath it and shining up through. Fig. 39 is a picture of three of us
+on the mountain-top, who saw a rarer spectacle; for directly opposite
+the setting sun, and on the mist over the gulf beyond us, was a bright
+ring, in whose centre were three phantom images of our three selves,
+which moved as we moved, and then faded as the sun sank. It was “the
+spectre of the Brocken.” These ghostly presentments were tolerably
+defined, as in the sketch, but did not seem to be gigantic, as some
+have described them. We rather thought them close at hand; but before
+we could determine, the vision faded.
+
+The clouds, to our good fortune, rolled away on the 29th; and a
+number of pleasure-seekers, who came up to view the eclipse and the
+unwonted bright sunshine, made a scene which it was hard to identify
+with the usual one. This time my business was to draw the corona; and
+the extreme altitude and the clearness of the air, with perhaps some
+greater extension than usual in the object itself, enabled it to be
+followed to an unprecedented distance. During totality the sun was
+surrounded by a narrow ring--hardly more than a line--of vivid light,
+presenting no structure to the naked eye (but a remarkable one in
+the telescope); and this faded with great suddenness into a circular
+nebulous luminosity between two and three diameters of the sun wide,
+but without such marked plumes, or filaments, as I had seen in 1869.
+The most extraordinary thing, however, was a beam of light, inclined
+at an angle of about forty-five degrees, about as wide as the sun,
+and extending to the distance of nearly six of its diameters on one
+side and over twelve on the other; on one side alone, that is, to the
+amazing distance of over ten million miles from its body. Substantially
+the same observation was made, as it appeared later, by Professor
+Newcomb, at a lower level. The direction, when more carefully measured,
+it was interesting to note, coincided closely with that of the Zodiacal
+light, and a faint central rib added to its resemblance to that body.
+It is noteworthy, in illustration of what has already been said as
+to the conflict of ocular testimony, that though I, with the great
+majority of observers below, saw only this beam, two witnesses whose
+evidence is unimpeachable, Professors Young and Abbe, saw a pale beam
+at right angles to it; and that one observer did not see the beam in
+question at all. Fig. 40 is a sketch made from my own, but necessarily
+on a scale which can show only its general features.
+
+With the telescope, the whole of the bright inner light close to the
+sun was found to be made up of filaments, more definite even than those
+described in a previous chapter as seen in sun-spots, and bristling in
+all directions from the edge; not concealing each other, as we might
+expect such things to do, upon a sphere, but fringing the sun’s edge in
+definite outline, as though it were really but a disk.
+
+[Illustration: FIG. 40.--OUTER CORONA OF 1878. (U. S. NAVAL
+OBSERVATORY.)]
+
+Those who were at leisure to watch the coming shadow of the moon
+described its curved outline as distinctly visible on the plains. “A
+rounded ball of darkness with an orange-yellow border,” one called
+it. Those, again, who looked down on the bright clouds below say the
+shadow was preceded by a yellow fringe, casting a bright light over
+the clouds and passing into orange, pink, rose-red, and dark-red, in
+about twenty seconds. This beautiful effect was noticed by nearly all
+the amateur observers present, who had their attention at liberty, and
+was generally unseen by the professional ones, who were shut up in dark
+tents with photometers, or engaged otherwise than in admiring the glory
+of the spectacle as a spectacle merely. This strange light, forming a
+band of color about the shadow as seen from above, must have really
+covered ten miles or more in width, and have occupied a considerable
+fraction of a minute in passing over the heads of those below, to whom
+it probably constituted that lurid light on their landscape I have
+spoken of as so peculiar and “unnatural.” It seems to be due to the
+colored flames round the sun, which shine out when its brighter light
+is extinguished. I should add that on the summit of Pike’s Peak the
+corona did not entirely disappear at the instant the sun broke forth
+again, but that its outlying portions first went and then its brighter
+and inner ones, till our eager gaze, trying to follow it as long as
+possible, only after the lapse of some minutes saw the last of the
+wonderful thing disappear and “fade into the light of common day.”
+
+[Illustration: FIG. 41.--SPECTROMETER SLIT AND SOLAR IMAGE. (FROM “THE
+SUN,” BY YOUNG.)]
+
+There have been other eclipses since; but, in spite of all, our
+knowledge of the corona remains very incomplete, and if the most
+learned in such matters were asked what it was, he could probably
+answer truthfully, “I don’t know.”
+
+[Illustration: FIG. 42.--SLIT AND PROMINENCES.
+
+(“THE SUN,” BY YOUNG.)]
+
+This will not be wondered at when it is considered that as total
+eclipses come, about every other year, and continue, one with another,
+hardly three minutes, an astronomer who should devote thirty years
+exclusively to the subject, never missing an eclipse in whatever
+quarter of the globe it occurred, would in that time have secured,
+in all, something like three-quarters of an hour for observation.
+Accordingly, what we know best about the corona is how it looks, what
+it _is_ being still largely conjecture; and it is for this reason that
+I have thought the space devoted to it would be best used by giving the
+unscientific reader some idea of the visible phenomena as they present
+themselves to an eyewitness. Treatises like Lockyer’s “Solar Physics,”
+Proctor’s “The Sun,” Secchi’s “Le Soleil,” and Young’s “The Sun” (the
+latter is most recent), will give the reader who desires to learn more
+of the little that is known, the fuller information which this is not
+the place for; but it may be said very briefly that it is certain that
+the corona is at times of enormous extent (the whole length of the
+longer beam seen on Pike’s Peak must have been over fourteen million
+miles), that it almost certainly changes in its shape and dimensions
+from year to year (possibly much oftener, but this we cannot yet
+know), and that it shines partly by its own and partly by reflected
+light. When we come to ask whether it is a gas or not, the evidence
+is conflicting. The appearance of the green coronal line, and other
+testimony we have not alluded to, would make it seem almost certain
+that there must be a gas here of extreme tenuity, reaching the height
+of some hundred thousand miles, at the least; while yet the fact that
+such light bodies as comets have been known to pass through it, close
+to the sun, without suffering any visible retardation, such as would
+come even from a gas far lighter than hydrogen, appears to throw doubt
+on evidence otherwise strong. It is possible to conceive of the corona,
+and especially of the outer portion, as very largely made up of minute
+particles such as form the scattered dust of meteoric trains, and this
+seems to be the most probable constitution of its outlying parts. It
+is even possible to conceive that it is in some degree a subjective
+phenomenon, caused, as Professor Hastings has suggested, by diffraction
+upon the edge of the moon,--the moon, that is, not merely serving as a
+screen to the sun to reveal the corona, but partly _making_ the corona
+by diffracting the light, somewhat as we see that the edge of any very
+distant object screening the sun is gilded by its beams. This effect
+may be seen when the sun rises or sets unusually clear, for objects on
+the horizon partly hiding it are then fringed for a moment with a line
+of light,--an appearance which has not escaped Shakspeare, where he
+says,--
+
+    “But when from under this terrestrial ball
+    He fires the tall tops of the eastern pines.”
+
+Still, in admitting the possibility of some such contributory effect on
+the part of the moon, we must not, of course, be understood as meaning
+that the corona as a whole does not have a real existence, quite
+independent of the changes which the presence of the moon may bring;
+and in leaving the wonderful thing we must remember that it is, after
+all, a reality, and not a phantasm.
+
+[Illustration: FIG. 43.--TACCHINI’S CHROMOSPHERIC CLOUDS. (“MEMORIE
+DEGLI SPETTROSCOPISTI ITALIANI.”)]
+
+[Illustration: FIG. 44.--TACCHINI’S CHROMOSPHERIC CLOUDS. (“MEMORIE
+DEGLI SPETTROSCOPISTI ITALIANI.”)]
+
+I have already described how, at the eclipse of 1870, I (with others)
+saw within the corona what seemed like rose and scarlet-colored
+mountains rising from the sun’s edge, an appearance which had first
+been particularly studied in the eclipse of 1868, two years before, and
+which, it might be added, Messrs. Lockyer and Janssen had succeeded in
+observing without an eclipse by the spectroscope. Besides the corona,
+it may be said, then, that the sun is surrounded by a thin envelope,
+rising here and there into prominences of a rose and scarlet color,
+invisible in the telescope, except at a total eclipse, but always
+visible through the spectroscope. It is within and quite distinct
+from the corona, and is usually called the “chromosphere,” being a
+sort of sphere of colored fire surrounding the sun, but which we can
+usually see only on the edge. “The appearance,” says Young, “is as if
+countless jets of heated gas were issuing through vents and spiracles
+over the whole surface, thus clothing it with flame, which heaves and
+tosses like the blaze of a conflagration.” Out of this, then, somewhat
+like greater waves or larger swellings of the colored fires, rise the
+prominences, whose place, close to the sun’s edge, has been indicated
+in many of the drawings and photographs just given of the corona, on
+whose background they are seen during eclipses; but as they can be
+studied at our leisure with the spectroscope, we have reserved a more
+particular description of them till now. They are at all times directly
+before us, as well as the corona; but while both are yet invisible from
+the overpowering brightness of the sunlight reflected from the earth’s
+atmosphere in front of them, these red flames are so far brighter than
+the coronal background, that if we could only weaken this “glare” a
+little, they at least might become visible, even if the corona were
+not. The difficulty is evidently to find some contrivance which will
+weaken the “glare” without enfeebling the prominences too; and this the
+spectroscope does by diffusing the white sunlight, while it lets the
+color pass nearly unimpaired. For the full understanding of its action
+the reader must be referred to such works as those on the sun already
+mentioned; but a general idea of it may be gathered, if we reflect
+that white light is composed of every possible variety of colors, and
+that the spectroscope, which consists essentially of a prism behind a
+very narrow slit through which the light enters, lets any single color
+pass freely, without weakening it or altering it in anything but its
+direction, but gives a different direction to each, and hence sorts out
+the tints, distributing them side by side, every one in its own place,
+upon the long colored band called the spectrum. If this distribution
+has spread the colors along a space a thousand times as wide as the
+original beam, the average light must be just so much weaker than the
+white light was, because this originally consisted of a thousand (let
+us say a thousand, but it is really an infinite number) mingled tints
+of blue, green, yellow, orange, and red, which have now been thus
+distributed. If, however, we look through the prism at a rose-leaf, and
+it has no blue, green, yellow, or orange in it, and nothing but pure
+red, as each single color passes unchanged, this red will, according
+to what has been said, be as bright after it has passed as before. All
+depends, then, on the fact that these prominences do consist mainly
+of light of one color, like the rose-leaf, so that this monochromatic
+light will be seen through the spectroscope just as it is, while the
+luminous veil of glaring white before it will seem to be brushed away.
+
+If a large telescope be directed toward the sun, the glass at the
+farther end will, if we remove the eye-piece, form a little picture
+of the sun, as a picture is formed in a camera-obscura; and now, if
+we also fasten the spectroscope to this eye-end, where the observer’s
+head would be were he looking through, the edge of the solar image may
+be made to fall just _off_ the slit, so that only the light from the
+prominences (and the white glare about them) shall pass in. To see
+this more clearly, let us turn our backs to the sun and the telescope,
+and look at the place where the image falls by the spectroscope slit,
+which in Fig. 41 is drawn of its full size. This is a brass plate,
+having a minute rectangular window, the “slit,” in it. The width of
+this slit is regulated by a screw, and any rays falling into the
+narrow aperture pass through the prism within, and finally fall on the
+observer’s eye, but not till they have been sorted by the prism in
+the manner described. Formed on the brass plate, just as it would be
+formed on a sheet of paper, or anything else held in the focus, we see
+the bright solar image, a circle of light perhaps an inch and a half
+in diameter,--a miniature of the sun with its spots. The whole of the
+sun (the photosphere) then is hidden to an observer who is looking up
+through the slit from the other side, for, as the sun’s edge does not
+quite touch the slit, none of its rays can enter it; but if there be
+also the image here of a prominence, projecting beyond the edge, and
+really overhanging the slit (though to us invisible on account of the
+glare about it), these rays will fall into the slit and pass down to
+the prism, which will dispose of it in the way already stated.
+
+[Illustration: FIG. 45.--VOGEL’S CHROMOSPHERIC FORMS. (“BEOBACHTUNGEN,”
+DR. H. C. VOGEL.)]
+
+And now let us get to the other side, and, looking up through the prism
+with the aid of a magnifying-glass, see what it has done for us (Fig.
+42). The large rectangular opening here is the same as the small one
+which was visible from the outside, only that it is now magnified, and
+what was before invisible is seen; the edge of the sun itself is just
+hidden, but the scarlet flames of the chromosphere have become visible,
+with a cloudy prominence rising above them. The “flames” are flame-like
+only in form, for their light is probably due not to any combustion,
+but to the glow of intensely heated matter; and as its light is not
+quite pure red, we can, by going to another part of the spectrum, see
+the same thing repeated in orange, the effect being as though we had a
+number of long narrow windows, some glazed with red, some with orange,
+and some with other colors, through which we could look out at the
+same clouds. I have looked at these prominences often in this way; but
+I prefer, in the reader’s interest, to borrow from the description by
+Professor Young, who has made these most interesting and wonderful
+forms a special study.
+
+Let us premise that the depth of the crimson shell out of which they
+rise is usually less than five thousand miles, and that though the
+prominences vary greatly, the majority reach a height of nearly twenty
+thousand miles, while in exceptional cases this is immensely exceeded.
+Professor Young has seen one which grew to a height of three hundred
+and fifty thousand miles in an hour and a half, and in half an hour
+more had faded away.
+
+These forms fall into two main classes,--that of the quiet and
+cloud-like, and that of the eruptive,--the first being almost exactly
+in form like the clouds of our own sky, sometimes appearing to lie on
+the limb of the sun like a bank of clouds on the horizon, sometimes
+floating entirely free; while sometimes “the whole under surface is
+fringed with down-hanging filaments, which remind one of a summer
+shower hanging from a heavy thunder-cloud.”
+
+Here are some of the typical forms of the quieter ones:--
+
+Fig. 43, by Tacchini, the Director of the Roman Observatory, represents
+an ordinary prominence, or cloud-group in the chromosphere, whose
+height is about twenty-five thousand miles. The little spires of flame
+which rise, thick as grass-blades, everywhere from the surface, are
+seen on its right and left.
+
+[Illustration: FIG. 46.--TACCHINI’S CHROMOSPHERIC FORMS. (“MEMORIE
+DEGLI SPETTROSCOPISTI ITALIANI.”)]
+
+Fig. 44 (Tacchini) is one where the agitation is greater and the
+“filamentary” type is more marked. Besides the curiously thread-like
+forms (so suggestive of what we have already seen in the photosphere),
+we have here what looks like an extended cloudy mass, drawn out by a
+horizontally moving wind.
+
+Fig. 45 (by Vogel, at Bothkamp) represents another of these numerous
+types.
+
+The extraordinary Fig. 46 is from another drawing, by Tacchini, of a
+protuberance seen in 1871 (a time of great solar disturbance), and it
+belongs to the more energetic of its class.
+
+[Illustration: FIG. 47.--ERUPTIVE PROMINENCES. (“THE SUN,” BY YOUNG.)]
+
+This fantastic cloud-shape, “if shape it might be called that shape had
+none,” looking like some nightmare vision, was about fifty thousand
+miles long and sixty thousand high above the surface. The reader will
+notice also the fiery rain, like the drops from a falling rocket, and
+may add to it all, in imagination, the actual color, which is of a deep
+scarlet.
+
+It may add to the-interest such things excite, to know that they
+have some mysterious connection with a terrestrial phenomenon,--the
+aurora,--for the northern lights have been again and again noticed to
+dance in company with these solar displays.
+
+The eruptive prominences are very different in appearance, as will be
+seen by the next illustration, for which we are indebted to Professor
+Young.
+
+In Fig. 47 we have a group of most interesting views by him (drawn
+here on the common scale of seventy-five thousand miles to an inch),
+illustrating the more eruptive types, of which we will let him speak
+directly. The first shows a case of the vertical filaments, like those
+rocket-drops we saw just, now in Tacchini’s drawing, but here more
+marked; while the second (on the left side) is a cyclone-form, where
+the twisted stems suggest what we have seen before in the “bridges” of
+sun-spots, and below this is another example of filamentary forms.
+
+The upper one, on the right, is the view of a cloud prominence as it
+appeared at _half-past twelve_ o’clock, on Sept. 7, 1871. Below it is
+the same prominence at _one_ o’clock (half an hour later), when it
+has been shattered by some inconceivable explosion, blowing it into
+fragments, and driving the hydrogen to a height of two hundred thousand
+miles. The lowest figure on the right shows another case where inclined
+jets (of hydrogen) were seen to rise to a height of fifty thousand
+miles.
+
+Professor Young says of these:--
+
+  “Their form and appearance change with great rapidity, so that
+  the motion can almost be seen with the eye. Sometimes they
+  consist of pointed rays, diverging in all directions, like
+  hedgehog-spines. Sometimes they look like flames; sometimes like
+  sheaves of grain; sometimes like whirling water-spouts, capped
+  with a great cloud; occasionally they present most exactly the
+  appearance of jets of liquid fire, rising and falling in graceful
+  parabolas; frequently they carry on their edges spirals like the
+  volutes of an Ionic column; and continually they detach filaments
+  which rise to a great elevation, gradually expanding and growing
+  fainter as they ascend, until the eye loses them. There is no end
+  to the number of curious and interesting appearances which they
+  exhibit under varying circumstances. The velocity of the motions
+  often exceeds a hundred miles a second, and sometimes, though
+  very rarely, reaches two hundred miles.”
+
+In the case of the particular phenomenon recorded by Professor Young in
+the last illustration, Mr. Proctor, however, has calculated that the
+initial velocity probably exceeded five hundred miles a second, which,
+except for the resistance experienced by the sun’s own atmosphere,
+would have hurled the ejected matter into space entirely clear of the
+sun’s power to recall it, so that it would never return.
+
+It adds to our interest in these flames to know that they at least are
+connected with that up-rush of heated matter from the sun’s interior,
+forming a part of the circulation which maintains both the temperature
+of its surface and that radiation on which all terrestrial life
+depends. The flames, indeed, add of themselves little to the heat the
+sun sends us, but they are in this way the outward and visible signs of
+a constant process within, by which we live; and so far they seem to
+have a more immediate interest to us, though invisible, than the corona
+which surrounds them. But we must remember when we lift our eyes to the
+sun that this latter wonder is really there, whether man sees it or
+not, and that the cause of its existence is still unknown.
+
+We ask for its “object” perhaps with an unconscious assumption that the
+whole must have been in some way provided to subserve _our_ wants; but
+there is not as yet the slightest evidence connecting its existence
+with any human need or purpose, and as yet we have no knowledge that,
+in this sense, it exists to any “end” at all. “As the thought of man is
+widened with the process of the suns,” let us hope that we shall one
+day know more.
+
+
+
+
+III.
+
+THE SUN’S ENERGY.
+
+
+“It is indeed,” says good Bishop Berkeley, “an opinion strangely
+prevailing amongst men that ... all sensible objects have an existence
+... distinct from their being perceived by the understanding. But
+... some truths there are, so near and obvious to the mind, that a
+man need only open his eyes to see them. Such I take this important
+one to be, namely, that all the choir of heaven and furniture of the
+earth--in a word, all those bodies which compose the mighty frame of
+the world--have not any subsistence without a mind.”
+
+We are not going to take the reader along “the high priori road” of
+metaphysics, but only to speak of certain accepted conclusions of
+modern experimental physics, which do not themselves, indeed, justify
+all of Berkeley’s language, but to which these words of the author of
+“A New Theory of Vision” seem to be a not unfit prelude.
+
+When we see a rose-leaf, we see with it what we call a color, and we
+are apt to think it is in the rose. But the color is in _us_, for it is
+a sensation which something coming from the sun excites in the eye; so
+that if the rose-leaf were still there, there would be no color unless
+there were an eye to receive and a brain to interpret the sensation.
+Every color that is lovely in the rainbow or the flower, every hue
+that is vivid in a ribbon or sombre in the grave harmonies of some
+old Persian rug, the metallic lustre of the humming-bird or the sober
+imperial yellow of precious china,--all these have no existence as
+color apart from the seeing eye, and all have their fount and origin in
+the sun itself.
+
+“Color” and “light,” then, are not, properly speaking, external things,
+but names given to the sensations caused by an uncomprehended something
+radiated from the sun, when this falls on our eyes. If this very same
+something falls on our face, it produces another kind of sensation,
+which we call “heat,” or if it falls on a thermometer it makes it rise;
+while if it rests long on the face it will produce yet another effect,
+“chemical action,” for it will _tan_ the cheek, producing a chemical
+change there; or it will do the like work more promptly if it meet a
+photographic plate. If we bear in mind that it is the identically same
+thing (whatever that is) which produces all these diverse effects, we
+see, some of us perhaps for the first time, that “color,” “light,”
+“radiant heat,” “actinism,” etc., are only names given to the diverse
+effects of some thing, not things themselves; so that, for instance,
+all the splendor of color in the visible world _exists only in the
+eye that sees it_. The reader must not suppose that he is here being
+asked to entertain any metaphysical subtlety. We are considering a fact
+almost universally accepted within the last few years by physicists,
+who now generally admit the existence of a something coming from the
+sun, which is not itself light, heat, or chemical action, but of which
+these are effects. When we give this unknown thing a name, we call it
+“radiant energy.”
+
+How it crosses the void of space we cannot be properly said to know,
+but all the phenomena lead us to think it is in the form of motion
+in some medium,--somewhat (to use an imperfect analogy) like the
+transmission through the air of the vibrations which will cause sound
+when they reach an ear. This, at any rate, is certain, that there is an
+action of some sort incessantly going on between us and the sun, which
+enables us to experience the effects of light and heat. We assume
+it to be a particular mode of vibration; but whatever it is, it is
+repeated with incomprehensible rapidity. Experiments recently made by
+the writer show that the _slower_ heat vibrations which reach us from
+the sun succeed each other nearly 100,000,000,000,000 times in a single
+second, while those which make us see, have long been known to be more
+rapid still. These pass outward from the sun in every direction, in
+ever-widening spheres; and in them, so far as we know, lies the potency
+of life for the planet upon whose surface they fall.
+
+Did the reader ever consider that next to the mystery of gravitation,
+which draws all things on the earth’s surface down, comes that
+mystery--not seen to be one because so familiar--of the occult force
+in the sunbeams which lifts things _up_? The incomprehensible energy
+of the sunbeam brought the carbon out of the air, put it together in
+the weed or the plant, and lifted each tree-trunk above the soil. The
+soil did not lift it, any more than the soil in Broadway lifted the
+spire of Trinity. Men brought stones there in wagons to build the
+church, and the sun brought the materials in its own way, and built up
+alike the slender shaft that sustains the grass blade and the column
+of the pine. If the tree or the spire fell, it would require a certain
+amount of work of men or horses or engines to set it up again. So much
+actual work, at least, the sun did in the original building; and if we
+consider the number of trees in the forest, we see that this alone is
+something great. But besides this, the sun locked up in each tree a
+store of energy thousands of times greater than that which was spent in
+merely lifting the trunk from the ground, as we may see by unlocking
+it again, when we burn the tree under the boiler of an engine; for it
+will develop a power equal to the lifting of thousands of its kind,
+if we choose to employ it in this way. This is so true, that the tree
+may fall, and turn to coal in the soil, and still keep this energy
+imprisoned in it,--keep it for millions of years, till the black lump
+under the furnace gives out, in the whirling spindles of the factory or
+the turning wheel of the steamboat, the energy gathered in the sunshine
+of the primeval world.
+
+The most active rays in building up plant-life are said to be the
+yellow and orange, though Nature’s fondness for green everywhere is
+probably justified by some special utility. At any rate, the action
+of these solar rays is to decompose the products of combustion, to
+set free the oxygen, and to fix the carbon in the plant. Perhaps
+these words do not convey a definite meaning to the reader, but it
+is to be hoped they will, for the statement they imply is wonderful
+enough. Swift’s philosopher at Laputa, who had a project for extracting
+sunbeams out of cucumbers, was wiser than his author knew; for
+cucumbers, like other vegetables, are now found to be really in large
+part put together by sunbeams, and sunbeams, or what is scarcely
+distinguishable from such, could with our present scientific knowledge
+be extracted from cucumbers again, only the process would be too
+expensive to pay. The sunbeam, however, does what our wisest chemistry
+cannot do: it takes the burned out ashes and makes them anew into green
+wood; it takes the close and breathed out air, and makes it sweet and
+fit to breathe by means of the plant, whose food is the same as our
+poison. With the aid of sunlight a lily would thrive on the deadly
+atmosphere of the “black hole of Calcutta;” for this bane to us, we
+repeat, is vital air to the plant, which breathes it in through all its
+pores, bringing it into contact with the chlorophyl, its green blood,
+which is to it what the red blood is to us; doing almost everything,
+however, by means of the sun ray, for if this be lacking, the oxygen is
+no longer set free or the carbon retained, and the plant dies. This too
+brief statement must answer instead of a fuller description of how the
+sun’s energy builds up the vegetable world.
+
+But the ox, the sheep, and the lamb feed on the vegetable, and we in
+turn on them (and on vegetables too); so that, though we might eat
+our own meals in darkness and still live, the meals themselves are
+provided literally at the sun’s expense, virtue having gone out of him
+to furnish each morsel we put in our mouths. But while he thus prepares
+the material for our own bodies, and while it is plain that without him
+we could not exist any more than the plant, the processes by which he
+acts grow more intricate and more obscure in our own higher organism,
+so that science as yet only half guesses how the sun makes us. But the
+making is done in some way by the sun, and so almost exclusively is
+every process of life.
+
+It is not generally understood, I think, how literally true this is
+of every object in the organic world. In a subsequent illustration
+we shall see a newspaper being printed by power directly and visibly
+derived from the sunbeam. But all the power derived from coal, and all
+the power derived from human muscles, comes originally from the sun,
+in just as literal a sense; for the paper on which the reader’s eye
+rests was not only made primarily from material grown by the sun, but
+was stitched together by derived sun-power, and by this, also, each
+page was printed, so that the amount of this solar radiation expended
+for printing each chapter of this book could be stated with approximate
+accuracy in figures. To make even the reader’s hand which holds this
+page, or the eye which sees it, energy again went out from the sun; and
+in saying this I am to be understood in the plain and common meaning of
+the words.
+
+Did the reader ever happen to be in a great cotton-mill, where many
+hundreds of operatives watched many thousands of spindles? Nothing is
+visible to cause the multiplied movement, the engine being perhaps away
+in altogether another building. Wandering from room to room, where
+everything is in motion derived from some unseen source, he may be
+arrested in his walk by a sudden cessation of the hum and bustle,--at
+once on the floor below, and on that above, and all around him. The
+simultaneousness of this stoppage at points far apart when the steam
+is turned off, strikes one with a sense of the intimate dependence of
+every complex process going on upon some remote invisible motor. The
+cessation is not, however, absolutely instantaneous; for the great
+fly-wheel, in which a trifling part of the motor power is stored, makes
+one or two turns more, till the energy in this also is exhausted,
+and all is still. The coal-beds and the forests are to the sun what
+the fly-wheel is to the engine: all their power comes from him; they
+retain a little of it in store, but very little by comparison with the
+original; and were the change we have already spoken of to come over
+the sun’s circulation,--were the solar engine disconnected from us,--we
+could go on perhaps a short time at the cost of this store, but when
+this was over it would be over with us, and all would be still here too.
+
+Is there not a special interest for us in that New Astronomy which
+considers these things, and studies the sun, not only in the heavens as
+a star, but in its workings here, and so largely in its relations to
+man?
+
+       *       *       *       *       *
+
+Since, then, we are the children of the sun, and our bodies a product
+of its rays, as much as the ephemeral insects that its heat hatches
+from the soil, it is a worthy problem to learn how things earthly
+depend upon this material ruler of our days. But although we know it
+does nearly all things done on the earth, and have learned a little of
+the way it builds up the plant, we know so little of the way it does
+many other things here that we are still often only able to connect the
+terrestrial effect with the solar cause by noting what events happen
+together. We are in this respect in the position of our forefathers,
+who had not yet learned the science of electricity, but who noted
+that when a flash of lightning came a clap of thunder followed, and
+concluded as justly as Franklin or Faraday could have done that there
+was a physical relation between them. Quite in this way, we who are in
+a like position with regard to the New Astronomy, which we hope will
+one day explain to us what is at present mysterious in our connection
+with the sun, can as yet often only infer that when certain phenomena
+there are followed or accompanied by others here, all are really
+connected as products of one cause, however dissimilar they may look,
+and however little we know what the real connection may be.
+
+There is no more common inquiry than as to the influence of sun-spots
+on the weather; but as we do not yet know the real nature of the
+connection, if there be any, we can only try to find out by assembling
+independent records of sun-spots and of the weather here, and noticing
+if any changes in the one are accompanied by changes in the other; to
+see, for instance, if when sun-spots are plenty the weather the world
+over is rainy or not, or to see if when an unusual disturbance breaks
+out in a sun-spot any terrestrial disturbance is simultaneously noted.
+
+[Illustration: FIG. 48.--SUN-SPOTS AND PRICE OF GRAIN. (FROM
+“OBSERVATIONS OF SOLAR SPOTS.”)]
+
+When we remember how our lives depend on a certain circulation in
+the sun, of which the spots appear to be special examples, it is of
+interest not only to study the forms within them, as we have already
+been doing here, but to ask whether the spots themselves are present
+as much one year as another. The sun sometimes has numerous spots on
+it, and sometimes none at all; but it does not seem to have occurred to
+any one to see whether they had any regular period for coming or going,
+till Schwabe, a magistrate in a little German town, who happened to
+have a small telescope and a good deal of leisure, began for his own
+amusement to note their number every day. He commenced in 1826, and
+with German patience observed daily for forty years. He first found
+that the spots grew more numerous in 1830, when there was no single
+day without one; then the number declined very rapidly, till in 1833
+they were about gone; then they increased in number again till 1838,
+then again declined; and so on, till it became evident that sun-spots
+do not come and go by chance, but run through a cycle of growth and
+disappearance, on the average about once in every eleven years. While
+amusing himself with his telescope, an important sequence in Nature had
+thus been added to our knowledge by the obscure Hofrath Schwabe, who
+indeed compares himself to Saul, going out to seek his father’s asses
+and finding a kingdom. Old records made before Schwabe’s time have
+since been hunted up, so that we have a fairly connected history of the
+sun’s surface for nearly a hundred and fifty years; and the years when
+spots will be plentiful or rare can now be often predicted from seeing
+what has been in the past. Thus I may venture to say that the spots, so
+frequent in 1885, will have probably nearly disappeared in 1888, and
+will be probably very plentiful in 1894. I do not know at all why this
+is likely to happen; I only know that it has repeatedly happened at
+corresponding periods in the past.
+
+“Now,” it may be asked, “have these things any connection with weather
+changes, and is it of any practical advantage to know if they have?”
+
+Would it be, it may be answered, of any practical interest to a
+merchant in bread-stuffs to have private information of a reliable
+character that crops the world over would be fine in 1888 and fail in
+1894? The exclusive possession of such knowledge might plainly bring
+“wealth beyond the dreams of avarice” to the user; or, to ascend
+from the lower ground of personal interest to the higher aims of
+philanthropy and science, could we predict the harvests, we should
+be armed with a knowledge that might provide against coming years of
+famine, and make life distinctly happier and easier to hundreds of
+millions of toilers on the earth’s surface.
+
+“But can we predict?” We certainly cannot till we have, at any rate,
+first shown that there is a connection between sun-spots and the
+weather. Since we know nothing of the ultimate causes involved, we can
+only at present, as I say, collect records of the changes there, and
+compare them with others of the changes here, to see if there is any
+significant coincidence. To avoid columns of figures, and yet to enable
+the reader to judge for himself in some degree of the evidence, I will
+give the results of some of these records represented graphically by
+curves, like those which he may perhaps remember to have seen used to
+show the fluctuations in the value of gold and grain, or of stocks in
+the stock-market. It is only fair to say that mathematicians used this
+method long before it was ever heard of by business men, and that the
+stockbrokers borrowed it from the astronomers, and not the astronomers
+from them.
+
+In Fig. 48, from Carrington’s work, each horizontal space represents
+ten years of time, and the figures in the upper part represent the
+fluctuations of the sun-spot curve. In the middle curve, variations
+in vertical distances correspond to differences in the distance from
+the sun of the planet Jupiter, the possibility of whose influence
+on sun-spot periods can thus be examined. In the third and lowest,
+suggested by Sir William Herschel, the figures at the side are
+proportional to the price of wheat in the English market, rising when
+wheat ruled high, falling when it was cheap. In all three curves
+one-tenth of a horizontal spacing along the top or bottom corresponds
+to one year; and in this way we have at a glance the condensed result
+of observations and statistics for sixty years, which otherwise stated
+would fill volumes. The result is instructive in more ways than one.
+The variations of Jupiter’s distance certainly do present a striking
+coincidence with the changes in spot frequency, and this may indicate
+a real connection between the phenomena; but before we decide that
+it does so, we must remember that the number of cycles of change
+presented by the possible combination of planetary periods is all but
+infinite. Thus we might safely undertake, with study enough, to find a
+curve, depending solely on certain planetary configurations, which yet
+would represent with quite striking agreement for a time the rise and
+fall in any given railroad stock, the relative numbers of Democratic
+and Republican congressmen from year to year, or anything else with
+which the heavenly bodies have in reality as little to do. The third
+curve (meant by the price of wheat to test the possible influence of
+sun-spots on years of good or bad harvests) is not open to the last
+objection, but involves a fallacy of another kind. In fact the price
+of wheat depends on many things quite apart from the operations of
+Nature,--on wars and legislation, for instance; and here the great
+rise in the first years of the century is as clearly connected with the
+great continental wars of the first Napoleon, which shut up foreign
+ports, as the sudden fall about 1815, the year of Waterloo, is with
+the subsequent peace. Meanwhile an immense amount of labor has been
+spent in making tables of the weather, and of almost every conceivable
+earthly phenomenon which may be supposed to have a similar periodic
+character, with very doubtful success, nearly every one having brought
+out some result which might be plausible if it stood alone, but which
+is apt to be contradicted by the others. For instance, Mr. Stone,
+at the Cape of Good Hope, and Dr. Gould, in South America, consider
+that the observations taken at those places show a little diminution
+of the earth’s temperature (amounting to one or two degrees) at a
+sun-spot maximum. Mr. Chambers concludes, from twenty-eight years’
+observations, that the hottest are those of most sun-spots. So each of
+these contradicts the other. Then we have Gelinck, who, from a study of
+numerous observations, concludes that all are wrong together, and that
+there is really no change in either way.
+
+[Illustration: FIG. 49.--SUN-SPOT OF NOV. 16, 1882, AND EARTH.]
+
+I might go on citing names with no better result. One observer
+tabulates observations of terrestrial temperature, or rain-fall, or
+barometer, or ozone; another, the visitations of Asiatic cholera; while
+still another (the late Professor Jevons) tabulates commercial crises
+with the serious attempt to find a connection between the sun-spots and
+business panics. Of making such cycles there is no end, and much study
+of them would be a weariness I will not inflict.
+
+[Illustration: FIG. 50.--GREENWICH RECORD OF DISTURBANCE OF MAGNETIC
+NEEDLE, NOV. 16 AND 17, 1882.]
+
+Our own conclusion is, that from such investigations of terrestrial
+changes nothing is yet certainly known with regard to the influence
+of sun-spots on the weather. There is, however, quite another way;
+that is, to measure their effect at the origin in the sun itself.
+The sun-spot is cooler than the rest of the surface, and it might be
+thought that when there are many the sun would give less heat. As far
+as the spots themselves are concerned, this is so, but in a very small
+degree. I have been able to ascertain how much this deprivation of heat
+amounts to, and find it is a real but a most insignificant quantity,
+rising to about two-thirds of one degree Fahrenheit every eleven
+years. This, it will be remembered, is the direct effect of the spots
+considered merely as so many cool patches on the surface, and it does
+not imply that when there are most spots the sun will necessarily give
+less heat. In fact there may be a compensating action accompanying them
+which makes the radiation greater than when they are absent. I will not
+enter on a detailed explanation, but only say that in the best judgment
+I can form by a good deal of study and direct experiment, there is no
+certain evidence that the sun is hotter at one time than at another.
+
+If we investigate, however, the connection between spots and
+terrestrial magnetic disturbances, we shall find altogether more
+satisfactory testimony. This evidence is of all degrees of strength,
+from probability up to what may be called certainty, and it is always
+obtained, not by _a priori_ reasoning, but by the comparison of
+independent observations of something which has happened on the sun and
+on the earth. We will first take an instance of what we consider the
+weakest degree of evidence (weak, that is, when any such single case
+is considered), and we do so by simply quoting textually three records
+which were made at nearly the same time in different parts of the world
+in 1882.
+
+A certain spot had been visible on the sun at intervals for some weeks;
+but when on the 16th of November a glimpse was caught of it after
+previous days of cloudy weather, the observer, it will be seen, is
+struck by the great activity going on in it, and, though familiar with
+such sights, describes this one as “magnificent.”
+
+1. From the daily record at the Allegheny Observatory, November 16,
+1882:--
+
+  “Very large spot on the sun; ... great variety of forms; inrush
+  from S. E. to S. W.; tendency to cyclonic action at several
+  points. The spot is apparently near its period of greatest
+  activity. A magnificent sight.”
+
+At the same time a sketch was commenced which was interrupted by the
+cloudy weather of this and following days. The outline of the main spot
+only is here given (Fig. 49). Its area, as measured at Allegheny, was
+2,200,000,000 square miles; at Greenwich its area, inclusive of some
+outlying portions, was estimated on the same day to be 2,600,000,000
+square miles. The earth is shown of its relative size upon it, to give
+a proper idea of the scale.
+
+2. From the “New York Tribune” of November 18th (describing what took
+place in the night preceding the 17th):--
+
+
+  AN ELECTRIC STORM.
+
+  TELEGRAPH WIRES GREATLY AFFECTED.
+
+  THE DISTURBANCE WIDE-SPREAD.
+
+  ... At the Mutual Union office the manager said, “Our wires are
+  all running, but very slowly. There is often an intermission of
+  from one to five minutes between the words of a sentence. The
+  electric storm is general as far as our wires are concerned.”...
+  The cable messages were also delayed, in some cases as much as an
+  hour.
+
+  The telephone service was practically useless during the day.
+
+  WASHINGTON, _Nov. 17_.--A magnetic storm of more than usual
+  intensity began here at an early hour this morning, and has
+  continued with occasional interruptions during the day,
+  seriously interfering with telegraphic communication.... As
+  an experiment one of the wires of the Western Union Telegraph
+  Company was worked between Washington and Baltimore this
+  afternoon with the terrestrial current alone, the batteries
+  having been entirely detached.
+
+  CHICAGO, _Nov. 17_.--An electric storm of the greatest violence
+  raged in all the territory to points beyond Omaha.... The
+  switch-board here has been on fire a dozen times during the
+  forenoon. At noon only a single wire out of fifteen between this
+  city and New York was in operation.
+
+And so on through a column.
+
+3. In Fig. 50 we give a portion of the automatic trace of the magnetic
+needles at Greenwich.[3] These needles are mounted on massive piers in
+the cellars of the observatory, far removed from every visible source
+of disturbance, and each carries a small mirror, whence a spot of light
+is reflected upon a strip of photographic paper, kept continually
+rolling before it by clock-work. If the needle is still, the moving
+strip of paper will have a straight line on it, traced by the point of
+light, which is in this case motionless. If the needle swings to the
+right or left, the light-spot vibrates with it, and the line it traces
+becomes sinuous, or more and more sharply zigzagged as the needle
+shivers under the unknown forces which control it.
+
+    [3] It appears here through the kindness of the Astronomer
+        Royal. We regret to say that American observers are
+        dependent on the courtesy of foreign ones in such matters,
+        the United States having no observatory where such records
+        of sun-spots and magnetic variation are systematically kept.
+
+The upper part of Fig. 50 gives a little portion of this automatic
+trace on November 16th before the disturbance began, to show the
+ordinary daily record, which should be compared with the violent
+perturbation occurring simultaneously with the telegraphic disturbance
+in the United States. We may, for the reader’s convenience, remark
+that as the astronomical day begins twelve hours later than the civil
+day, the approximate Washington mean times, corresponding to the
+Greenwich hours after twelve, are found by adding one to the days and
+subtracting seventeen from the hours. Thus “November 16th, twenty-two
+hours” corresponds in the eastern United States nearly to five o’clock
+in the morning of November 17th.
+
+The Allegheny observer, it will be remembered, in his glimpse of the
+spot on November 16th, was struck with the great activity of the
+internal motions then going on in it. The Astronomer Royal states that
+a portion of the spot became detached on November 17th or 18th, and
+that several small spots which broke out in the immediate neighborhood
+were seen for the first time on the photographs taken November 17th,
+twenty-two hours.
+
+“Are we to conclude from this,” it may be asked, “that what went on
+in the sun was the cause of the trouble on the telegraph wires?” I
+think we are not at all entitled to conclude so from this instance
+_alone_; but though in one such case, taken by itself, there is nothing
+conclusive, yet when such a degree of coincidence occurs again and
+again, the habitual observer of solar phenomena learns to look with
+some confidence for evidence of electrical disturbance here following
+certain kinds of disturbance there, and the weight of this part of the
+evidence is not to be sought so much in the strength of a single case,
+as in the multitude of such coincidences.
+
+We have, however, not only the means of comparing sun-spot _years_ with
+years of terrestrial electric disturbance, but individual instances,
+particular _minutes_ of sun-spot changes, with particular minutes of
+terrestrial change; and both comparisons are of the most convincing
+character.
+
+First, let us observe that the compass needle, in its regular and
+ordinary behavior, does not point constantly in any one direction
+through the day, but moves a very little one way in the morning, and
+back in the afternoon. This same movement, which can be noticed even
+in a good surveyor’s compass, is called the “diurnal oscillation,”
+and has long been known. It has been known, too, that its amount
+altered from one year to another; but since Schwabe’s observations it
+has been found that the changes in this variation and in the number
+of the spots went on together. The coincidences which we failed to
+note in the comparison of the spots with the prices of grain are here
+made out with convincing clearness, as the reader will see by a simple
+inspection of this chart (Fig. 51, taken from Professor Young’s work),
+where the horizontal divisions still denote years, and the height of
+the continuous curve the relative number of spots, while the height of
+the dotted curve is the amount of the magnetic variation. Though we
+have given but a part of the curve, the presumption from the agreement
+in the forty years alone would be a strong one that the two effects,
+apparently so widely remote in their nature, are really due to a common
+cause.
+
+[Illustration: FIG. 51.--SUN-SPOTS AND MAGNETIC VARIATIONS.]
+
+Here we have compared years with years; let us next compare minutes
+with minutes. Thus, to cite (from Mr. Proctor’s work) a well-known
+instance: On Sept. 1, 1869, at eighteen minutes past eleven, Mr.
+Carrington, an experienced solar observer, suddenly saw in the sun
+something brighter than the sun,--two patches of light, breaking out so
+instantly and so intensely that his first thought was that daylight
+was entering through a hole in the darkening screen he used. It was
+immediately, however, made certain that something unusual was occurring
+in the sun itself, across which the brilliant spots were moving,
+travelling thirty-five thousand miles in five minutes, at the end of
+which time (at twenty-three minutes past eleven) they disappeared from
+sight. By good fortune, another observer a few miles distant saw and
+independently described the same phenomenon; and as the minute had been
+noted, it was immediately afterward found that recording instruments
+registered a magnetic disturbance at the same time,--“at the very
+moment,” says Dr. Stewart, the director of the observatory at Kew.
+
+“By degrees,” says Sir John Herschel, “accounts began to pour in of
+... great electro-magnetic disturbances in every part of the world....
+At Washington and Philadelphia, in America, the telegraphic signal men
+received severe electric shocks. At Boston, in North America, a flame
+of fire followed the pen of Bain’s electric telegraph.” (Such electric
+disturbances, it may be mentioned, are called “electric storms,” though
+when they occur the weather may be perfectly serene to the eye. They
+are shown also by rapid vibrations of the magnetic needle, like those
+we have illustrated.)
+
+On Aug. 3, 1872, Professor Young, who was observing at Sherman in the
+Rocky Mountains, saw three notable paroxysms in the sun’s chromosphere,
+jets of luminous matter of intense brilliance being projected at 8h.
+45m., 10h. 30m., and 11h. 50m. of the local time. “At dinner,” he
+says, “the photographer of the party, who was making our magnetic
+observations, told me, before knowing anything about what I had been
+observing, that he had been obliged to give up work, his magnet having
+swung clear off the limb.” Similar phenomena were observed August 5th.
+Professor Young wrote to England, and received from Greenwich and
+Stonyhurst copies of the automatic record, which he gives, and which
+we give in Fig. 52. After allowing for difference of longitude, the
+reader who will take the pains to compare them may see for himself that
+both show a jump of the needles in the cellars at Greenwich at the same
+_minute_ in each of the four cases of outburst in the Rocky Mountains.
+
+[Illustration: FIG. 52.--GREENWICH MAGNETIC OBSERVATIONS, AUG. 3 AND 5,
+1872.]
+
+While we admit that the evidence in any single case is rarely so
+conclusive as in these; while we agree that the spot is not so much
+the cause of the change as the index of some other solar action which
+does cause it; and while we fully concede our present ignorance of
+the nature of this cause,--we cannot refuse to accept the cumulative
+evidence, of which a little has been submitted.
+
+It is only in rare cases that we can feel quite sure; and yet, in
+regard even to one of the more common and less conclusive ones, we
+may at least feel warranted in saying that if the reader forfeited
+a business engagement or missed an invitation to dinner through the
+failure of the telegraph or telephone on such an occasion as that of
+the 17th of November, 1882, the far-off sun-spot was not improbably
+connected with the cause.
+
+Probably we should all like to hear some at least equally positive
+conclusion about the weather also, and to learn that there was a
+likelihood of our being able to predict it for the next year, as the
+Signal Service now does for the next day; but there is at present
+no such likelihood. The study of the possible connection between
+sun-spots and the weather is, nevertheless, one that will always have
+great interest to many; for even if we set its scientific aim aside
+and consider it in its purely utilitarian aspect, it is evident that
+the knowledge how to predict whether coming harvests would be good or
+bad, would enable us to do for the whole world what Joseph’s prophetic
+vision of the seven good and seven barren years did for the land of
+Egypt, and confer a greater power on its discoverer than any sovereign
+now possesses. There is something to be said, then, for the cyclists;
+for if their zeal does sometimes outrun knowledge, their object is a
+worthy one, and their aims such as we can sympathize with, and of which
+none of us can say that there is any inherent impossibility in them,
+or that they may not conceivably yet lead to something. Let us not,
+then, treat the inquirer who tries to connect panics on ‘Change with
+sun-spots as a mere lunatic; for there is this amount of reason in his
+theory, that the panics, together with the general state of business,
+are connected in some obscure way with the good or bad harvests, and
+these again in some still obscurer way with changes in our sun.
+
+We may leave, then, this vision of forecasting the harvests and the
+markets of the world from a study of the sun, as one of the fair dreams
+for the future of our science. Perhaps the dream will one day be
+realized. Who knows?
+
+
+
+
+IV.
+
+THE SUN’S ENERGY (_Continued_).
+
+
+If we paused on the words with which our last chapter closed, the
+reader might perhaps so far gather an impression that the whole
+all-important subject of the solar energy was involved in mystery and
+doubt. But if it be indeed a mystery when considered in its essence, so
+are all things; while regarded separately in any one of its terrestrial
+effects of magnetic or chemical action, or of light or heat, it may
+seem less so. Since there is not room to consider all these aspects,
+let us choose the last, and look at this energy in its familiar form of
+the _heat_ by which we live.
+
+We, the human race, are warming ourselves at this great fire which
+called our bodies into being, and when it goes out we shall go too.
+What is it? How long has it been? How long will it last? How shall we
+use it?
+
+To look across the space of over ninety million miles, and to try to
+learn from that distance the nature of the solar heat, and how it is
+kept up, seemed to the astronomers of the last century a hopeless task.
+The difficulty was avoided rather than met by the doctrine that the sun
+was pure fire, and shone because “it was its nature to.” In the Middle
+Ages such an idea was universal; and along with it, and as a logical
+sequence of it, the belief was long prevalent that it was possible
+to make another such flame here, in the form of a lamp which should
+burn forever and radiate light endlessly without exhaustion. With
+the philosopher’s stone, which was to transmute lead into gold, this
+perpetual lamp formed a prime object of research for the alchemist and
+student of magic.
+
+We recall the use which Scott has made of the belief in this product
+of “gramarye” in the “Lay of the Last Minstrel,” where it is sought to
+open the grave of the great wizard in Melrose Abbey. It is midnight
+when the stone which covers it is heaved away, and Michael’s undying
+lamp, buried with him long ago, shines out from the open tomb and
+illuminates the darkness of the chancel.
+
+    “I would you had been there to see
+    The light break forth so gloriously;
+    That lamp shall burn unquenchably
+    Until the eternal doom shall be,”
+
+says the poet. Now we are at liberty to enjoy the fiction as a fiction;
+but if we admit that the art which could make such a lamp would indeed
+be a black art, which did not work under Nature’s laws, but against
+them, then we ought to see that as the whole conception is derived from
+the early notion of a miraculous constitution of the sun, the idea of
+an eternal self-sustained sun is no more permitted to us than that of
+an eternal self-sustained lamp. We must look for the cause of the sun’s
+heat in Nature’s laws, and we know those laws chiefly by what we see
+here.
+
+Before examining the source of the sun’s heat, let us look a little
+more into its amount. To find the exact amount of heat which it sends
+out is a very difficult problem, especially if we are to use all the
+refinements of the latest methods in determining it. The underlying
+principle, however, is embodied in an old method, which gives, it is
+true, rather crude results, but by so simple a treatment that the
+reader can follow it readily, especially if unembarrassed with details,
+in which most of the actual trouble lies. We must warn him in advance
+that he is going to be confronted with a kind of enormous sum in
+multiplication, for whose general accuracy he may, however, trust to us
+if he pleases. We have not attempted exact accuracy, because it is more
+convenient for him that we should deal with round numbers.
+
+[Illustration: FIG. 53.--ONE CUBIC CENTIMETRE.]
+
+[Illustration: FIG. 54.--POUILLET’S PYRHELIOMETER.]
+
+The apparatus which we shall need for the attack of this great problem
+is surprisingly simple, and moderate in size. Let us begin by finding
+how much sun-heat falls in a small known area. To do this we take a
+flat, shallow vessel, which is to be filled with water. The amount it
+contains is usually a hundred cubic centimetres (a centimetre being
+nearly four-tenths of an inch), so that if we imagine a tiny cubical
+box about as large as a backgammon die, or, more exactly, having each
+side just the size of this (Fig. 53), to be filled and emptied into the
+vessel one hundred times, we shall have a precise idea of its limited
+capacity. Into this vessel we dip a thermometer, so as to read the
+temperature of the water, seal all up so that the water shall not run
+out, and expose it so that the heat at noon falls perpendicularly on
+it. The apparatus is shown in Fig. 54, attached to a tree. The stem
+of the instrument holds the thermometer, which is upside down, its
+bulb being in the water-vessel. Now, all the sun’s rays do not reach
+this vessel, for some are absorbed by our atmosphere; and all the heat
+which falls on it does not stay there, as the water loses part of it
+by the contact of the air with the box outside, and in other ways.
+When allowance is made for these losses, we find that the sun’s heat,
+if all retained, would have raised the temperature of the few drops of
+water which would fill a box the size of our little cube (according
+to these latest observations) nearly three degrees of the centigrade
+thermometer in one minute,--a most insignificant result, apparently,
+as a measure of what we have been told is the almost infinite heat of
+the sun! But if we think so, we are forgetting the power of numbers, of
+which we are about to have an illustration as striking in its way as
+that which Archimedes once gave with the grains of sand.
+
+There is a treatise of his extant, in which he remarks (I cite from
+memory) that as some people believe it possible for numbers to express
+a quantity as great as that of the grains of sand upon the sea-shore,
+while others deny this, he will show that they can express one even
+larger. To prove this beyond dispute, he begins by taking a small
+seed, beside which he ranges single grains of sand in a line, till he
+can give the number of these latter which equal its length. Next he
+ranges seeds beside each other till their number makes up the length
+of a span; then he counts the spans in a stadium, and the stadia in
+the whole world as known to the ancients, at each step expressing his
+results in a number certainly _greater_ than the number of sand-grains
+which the seed, or the span, or the stadium, or finally the whole
+world, is thus successively shown to contain. He has then already got
+a number before his reader’s eyes demonstrably larger than that of all
+the grains of sand on the sea-shore; yet he does not stop, but steps
+off the earth into space, to calculate and express a number _greater_
+than that of all the grains of sand which would fill a sphere embracing
+the earth and the sun!
+
+We are going to use our little unit of heat in the same way, for
+(to calculate in round figures and in English measure) we find that
+we can set over nine hundred of these small cubes side by side in a
+square foot, and, as there are 28,000,000 feet in a square mile, that
+the latter would contain 25,000,000,000 of the cubes, placed side by
+side, touching each other, like a mosaic pavement. We find also, by
+weighing our little cup, that we should need to fill and empty it
+almost exactly a million times to exhaust a tank containing a ton of
+water. The sun-heat falling on one square mile corresponds, then, to
+over seven hundred and fifty tons of water raised _every minute_ from
+the freezing-point to boiling, which already is becoming a respectable
+amount!
+
+But there are 49,000,000 square miles in the cross-section of the
+earth exposed to the sun’s rays, which it would therefore need
+1,225,000,000,000,000,000 of our little dies to cover one deep; and
+therefore in each _minute_ the sun’s heat falling on the earth would
+raise to boiling 37,000,000,000 tons of water.
+
+We may express this in other ways, as by the quantity of ice it would
+melt; and as the heat required to melt a given weight of ice is 79/100
+of that required to bring as much water from the freezing to the
+boiling point, and as the whole surface of the earth, including the
+night side, is four times the cross-section exposed to the sun, we
+find, by taking 526,000 minutes to a year, that the sun’s rays would
+melt in the year a coating of ice over the whole earth more than one
+hundred and sixty feet thick.
+
+We have ascended already from our small starting-point to numbers which
+express the heat that falls upon the whole planet, and enable us to
+deal, if we wish, with questions relating to the glacial epochs and
+other changes in its history. We have done this by referring at each
+step to the little cube which we have carried along with us, and which
+is the foundation of all the rest; and we now see why such exactness
+in the first determination is needed, since any error is multiplied
+by enormous numbers. But now we too are going to step off the earth
+and to deal with numbers which we can still express in the same way
+if we choose, but which grow so large thus stated that we will seek
+some greater term of comparison for them. We have just seen the almost
+incomprehensible amount of heat which the sun must send the earth in
+order to warm its oceans and make green its continents; but how little
+this is to what passes us by! The earth as it moves on in its annual
+path continually comes into new regions, where it finds the same amount
+of heat already pouring forth; and this same amount still continues to
+fall into the empty space we have just quitted, where there is no one
+left to note it, and where it goes on in what seems to us utter waste.
+If, then, the whole annual orbit were set close with globes like ours,
+and strung with worlds like beads upon a ring, each would receive the
+same enormous amount the earth does now. But this is not all; for not
+only along the orbit, but above and below it, the sun sends its heat in
+seemingly incredible wastefulness, the final amount being expressible
+in the number of _worlds_ like ours that it could warm like ours, which
+is 2,200,000,000.
+
+We have possibly given a surfeit of such numbers, but we cannot escape
+or altogether avoid them when dealing with this stupendous outflow of
+the solar heat. They are too great, perhaps, to convey a clear idea to
+the mind, but let us before leaving them try to give an illustration of
+their significance.
+
+Let us suppose that we could sweep up from the earth all the ice and
+snow on its surface, and, gathering in the accumulations which lie
+on its Arctic and Antarctic poles, commence building with it a tower
+greater than that of Babel, fifteen miles in diameter, and so high as
+to exhaust our store. Imagine that it could be preserved untouched by
+the sun’s rays, while we built on with the accumulations of successive
+winters, until it stretched out 240,000 miles into space, and formed an
+ice-bridge to the moon, and that then we concentrated on it the sun’s
+whole radiation, neither more nor less than that which goes on every
+moment. In _one_ second the whole would be gone, melted, boiled, and
+dissipated in vapor. And this is the rate at which the solar heat is
+being (to human apprehension) _wasted_!
+
+Nature, we are told, always accomplishes her purpose with the least
+possible expenditure of energy. Is her purpose here, then, something
+quite independent of man’s comfort and happiness? Of the whole solar
+heat, we have just seen that less than 1/2,000,000,--less, that is,
+than the one twenty-thousandth part of one per cent,--is made useful
+to us. “But may there not be other planets on which intelligent life
+exists, and where this heat, which passes us by, serves other beings
+than ourselves?” There _may_ be; but if we could suppose all the other
+planets of the solar system to be inhabited, it would help the matter
+very little; for the whole together intercept so little of the great
+sum, that all of it which Nature bestows on man is still as nothing to
+what she bestows on some end--if end there be--which is to us as yet
+inscrutable.
+
+How is this heat maintained? Not by the miracle of a perpetual
+self-sustained flame, we may be sure. But, then, by what fuel is such a
+fire fed? There can be no question of simple burning, like that of coal
+in the grate, for there is no source of supply adequate to the demand.
+The State of Pennsylvania, for instance, is underlaid by one of the
+richest coal-fields of the world, capable of supplying the consumption
+of the whole country at its present rate for more than a thousand
+years to come. If the source of the solar heat (whatever that is) were
+withdrawn, and we were enabled to carry this coal there, and shoot it
+into the solar furnace fast enough to keep up the known heat-supply,
+so that the solar radiation would go on at just its actual rate, the
+time which this coal would last is easily calculable. It would not last
+days or hours, but the whole of these coal-beds would demonstrably be
+used up in rather less than one one-thousandth of a second! We find by
+a similar calculation that if the sun were itself one solid block of
+coal, it would have burned out to the last cinder in less time than man
+has certainly been on the earth. But during historic times there has as
+surely been no noticeable diminution of the sun’s heat, for the olive
+and the vine grow just as they did three thousand years ago, and the
+hypothesis of an actual burning becomes untenable. It has been supposed
+by some that meteors striking the solar surface might generate heat by
+their impact, just as a cannon-ball fired against an armor-plate causes
+a flash of light, and a heat so sudden and intense as to partly melt
+the ball at the instant of concussion. This is probably a real source
+of heat-supply so far as it goes, but it cannot go very far; and,
+indeed, if our whole world should fall upon the solar surface like an
+immense projectile, gathering speed as it fell, and finally striking
+(as it would) with the force due to a rate of over three hundred miles
+a second, the heat developed would supply the sun for but little more
+than sixty years.[4]
+
+    [4] These estimates differ somewhat from those of Helmholtz and
+        Tyndall, as they rest on later measures.
+
+It is not necessary, however, that a body should be moving rapidly to
+develop heat, for arrested motion always generates it, whether the
+motion be fast or slow, though in the latter case the mass arrested
+must be larger to produce the same result. It is in the slow settlement
+of the sun’s own substance toward its centre, as it contracts in
+cooling, that we find a sufficient cause for the heat developed.
+
+This explanation is often unsatisfactory to those who have not studied
+the subject, because the fact that heat is so generated is not made
+familiar to most of us by observation.
+
+Perhaps the following illustration will make the matter plainer. When
+we are carried up in a lift, or elevator, we know well enough that heat
+has been expended under the boiler of some engine to drag us up against
+the power of gravity. When the elevator is at the top of its course, it
+is ready to give out in descending just the same amount of power needed
+to raise it, as we see by its drawing up a nearly equal counterpoise
+in the descent. It can and must give out in coming down the power that
+was spent in raising it up; and though there is no practical occasion
+to do so, a large part of this power could, if we wished, be actually
+recovered in the form of heat again. In the case of a larger body,
+such as the pyramid of Ghizeh, which weighs between six and seven
+million tons, all the furnaces in the world, burning coal under all its
+engines, would have to supply their heat for a measurable time to lift
+it a mile high; and then, if it were allowed to come down, whether it
+tell at once or were made to descend with imperceptible slowness, by
+the time it touched the earth the same heat would be given out again.
+
+Perhaps the fact that the sun is gaseous rather than solid makes it
+less easy to realize the enormous weight which is consistent with this
+vaporous constitution. A cubic mile of hydrogen gas (the lightest
+substance known) would weigh much more at the sun’s surface than the
+Great Pyramid does here, and the number of these cubic miles in a
+stratum one mile deep below its surface is over 2,000,000,000,000! This
+alone is enough to show that as they settle downward as the solar globe
+shrinks, here is a _possible_ source of supply for all the heat the sun
+sends out. More exact calculation shows that it _is_ sufficient, and
+that a contraction of three hundred feet a year (which in ten thousand
+years would make a shrinkage hardly visible in the most powerful
+telescope) would give all the immense outflow of heat which we see.
+
+There is an ultimate limit, however, to the sun’s shrinking, and
+there must have been some bounds to the heat he can already have thus
+acquired; for--though the greater the original diameter of his sphere,
+the greater the gain of heat by shrinking to its present size--if the
+original diameter be supposed as great as possible, there is still a
+finite limit to the heat gained.
+
+Suppose, in other words, the sun itself and all the planets ground to
+powder, and distributed on the surface of a sphere whose radius is
+infinite, and that this matter (the same in amount as that constituting
+the present solar system) is allowed to fall together at the centre.
+The actual shrinkage cannot possibly be greater than in this extreme
+case; but even in this practically impossible instance, it is easy
+to calculate that the heat given out would not support the _present_
+radiation over eighteen million years, and thus we are enabled to look
+back over past time, and fix an approximate limit to the age of the sun
+and earth.
+
+We say “present” rate of radiation, because, so long as the sun is
+purely gaseous, its temperature rises as it contracts, and the heat
+is spent faster; so that in early ages before this temperature was as
+high as it is now, the heat was spent more slowly, and what could have
+lasted “only” eighteen million years at the present rate might have
+actually spread over an indefinitely greater time in the past; possibly
+covering more than all the æons geologists ask for.
+
+If we would look into the future, also, we find that at the present
+rate we may say that the sun’s heat-supply is enough to last for some
+such term as four or five million years before it sensibly fails. It
+is certainly remarkable that by the aid of our science man can look
+out from this “bank and shoal of time,” where his fleeting existence
+is spent, not only back on the almost infinite lapse of ages past, but
+that he can forecast with some sort of assurance what is to happen
+in an almost infinitely distant future, long after the human race
+itself will have disappeared from its present home. But so it is, and
+we may say--with something like awe at the meaning to which science
+points--that the whole future radiation cannot last so long as ten
+million years. Its probable life in its present condition is covered
+by about thirty million years. No reasonable allowance for the fall
+of meteors or for all other known causes of supply could possibly at
+the present rate of radiation raise the whole term of its existence to
+sixty million years.
+
+This is substantially Professor Young’s view, and he adds:--
+
+  “At the same time it is, of course, impossible to assert that
+  there has been no catastrophe in the past, no collision with
+  some wandering star ... producing a shock which might in a few
+  hours, or moments even, restore the wasted energy of ages.
+  Neither is it wholly safe to assume that there may not be ways,
+  of which we as yet have no conception, by which the energy
+  apparently lost in space may be returned. But the whole course
+  and tendency of Nature, so far as science now makes out, points
+  backward to a beginning and forward to an end. The present order
+  of things seems to be bounded both in the past and in the future
+  by terminal catastrophes which are veiled in clouds as yet
+  inscrutable.”
+
+There is another matter of interest to us as dwellers on this planet,
+connected not with the amount of the sun’s heat so much as with the
+degree of its temperature; for it is almost certain that a very
+little fall in the temperature will cause an immense and wholly
+disproportionate diminution of the heat-supply. The same principle may
+be observed in more familiar things. We can, for instance, warm quite
+a large house by a very small furnace, if we urge this (by a wasteful
+use of coal) to a dazzling white heat. If we now let the furnace cool
+to half this white-heat temperature, we shall be sure to find that
+the heat radiated has not diminished in proportion, but out of all
+proportion,--has sunk, for instance, not only to one-half what it was
+(as we might think it would do), but to perhaps a twentieth or even
+less, so that the furnace which heated the house can no longer warm a
+single room.
+
+The human race, as we have said, is warming itself at the great solar
+furnace, which we have just seen contains an internal source for
+generating heat enough for millions of years to come; but we have
+also learned that if the sun’s internal circulation were stopped,
+the surface would cool and shut up the heat inside, where it would
+do us no good. The _temperature_ of the surface, then, on which the
+rate of heat-emission depends, concerns us very much; and if we had
+a thermometer so long that we could dip its bulb into the sun and
+read the degrees on the stem here, we should find out what observers
+would very much like to know, and at present are disposed to quarrel
+about. The difficulty is not in measuring the heat,--for that we have
+just seen how to do,--but in telling what temperature corresponds to
+it, since there is no known rule by which to find one from the other.
+One certain thing is this--that we cannot by any contrivance raise
+the temperature in the focus of any lens or mirror beyond that of
+its source (practically we cannot do even so much); we cannot, for
+instance, by any burning-lens make the image of a candle as hot as the
+original flame. Whatever a thermometer may read when the candle-heat is
+concentrated on its bulb by a lens, it would read yet more if the bulb
+were dipped in the candle-flame itself; and one obvious application of
+this fact is that though we cannot dip our thermometer in the sun, we
+know that if we could do so, the temperature would at least be greater
+than any we get by the largest burning-glass. We need have no fear of
+making the burning-glass too big; the temperature at its solar focus is
+_always_ and necessarily lower than that of the sun itself.
+
+For some reason no very great burning-lens or mirror has been
+constructed for a long time, and we have to go back to the eighteenth
+century to see what can be done in this way. The annexed figure (Fig.
+55) is from a wood-cut of the last century, describing the largest
+burning-lens then or since constructed in France, whose size and
+mode of use the drawing clearly shows. All the heat falling on the
+great lens was concentrated on a smaller one, and the smaller one
+concentrated it in turn, till at the very focus we are assured that
+iron, gold, and other metals ran like melted butter. In England, the
+largest burning-lens on record was made about the same time by an
+optician named Parker for the English Government, who designed it as
+a present to be taken by Lord Macartney’s embassy to the Emperor of
+China. Parker’s lens was three feet in diameter and very massive, being
+seven inches thick at the centre. In its focus the most refractory
+substances were fused, and even the diamond was reduced to vapor, so
+that the temperature of the sun’s surface is at any rate higher than
+_this_.
+
+[Illustration: FIG. 55.--BERNIÈRES’S GREAT BURNING-GLASS. (AFTER AN OLD
+FRENCH PRINT.)]
+
+(What became of the French lens shown, it would be interesting to know.
+If it is still above ground, its fate has been better than that of the
+English one. It is said that the Emperor of China, when he got his
+lens, was much alarmed by it, as being possibly sent him by the English
+with some covert design for his injury. By way of a test, a smith was
+ordered to strike it with his hammer; but the hammer rebounded from
+the solid glass, and this was taken to be conclusive evidence of magic
+in the thing, which was immediately buried, and probably is still
+reposing under the soil of the Celestial Flowery Kingdom.)
+
+We can confirm the evidence of such burning-lenses as to the sun’s
+high temperature by another class of experiment, which rests on an
+analogous principle. We can make the comparison between the heat from
+some artificially heated object and that which would be given out
+from an equal area of the sun’s face. Now, supposing like emissive
+powers, if the latter be found the hotter, though we cannot tell what
+its temperature absolutely is, we can at least say that it is greater
+than that of the thing with which it is compared; so that we choose
+for comparison the hottest thing we can find, on a scale large enough
+for the experiment. One observation of my own in this direction I will
+permit myself to cite in illustration.
+
+Perhaps the highest temperature we can get on a large scale in the arts
+is that of molten steel in the Bessemer converter. As many may be as
+ignorant of what this is as I was before I tried the experiment, I will
+try to describe it.
+
+[Illustration: FIG. 56.--A “POUR” FROM THE BESSEMER CONVERTER.]
+
+The “converter” is an enormous iron pot, lined with fire-brick, and
+capable of holding thirty or forty thousand pounds of melted metal;
+and it is swung on trunnions, so that it can be raised by an engine
+to a vertical position, or lowered by machinery so as to pour its
+contents out into a caldron. First the empty converter is inclined,
+and fifteen thousand pounds of fluid iron streams down into the mouth
+from an adjacent furnace where it has been melted. Then the engine
+lifts the converter into an erect position, while an air-blast from
+a blowing-engine is forced in at the bottom and through the liquid
+iron, which has combined with it nearly half a ton of silicon and
+carbon,--materials which, with the oxygen of the blast, create a heat
+which leaves that of the already molten iron far behind. After some
+time the converter is tipped forward, and fifteen hundred pounds more
+of melted iron is added to that already in it. What the temperature
+of this last is, may be judged from the fact that though ordinary
+melted iron is dazzlingly bright, the melted metal in the converter
+is so much brighter still, that the entering stream is dark brown by
+comparison, presenting a contrast like that of chocolate poured into
+a white cup. The contents are now no longer iron, but liquid steel,
+ready for pouring into the caldron; and, looking from the front down
+into the inclined vessel, we see the almost blindingly bright interior
+dripping with the drainage of the metal running down its side, so that
+the circular mouth, which is twenty-four inches in diameter, presents
+the effect of a disk of molten metal of that size (were it possible to
+maintain such a disk in a vertical position). In addition, we have the
+actual stream of falling metal, which continues nearly a minute, and
+presents an area of some square feet. The shower of scintillations from
+this cataract of what seems at first “sunlike” brilliancy, and the area
+whence such intense heat and light are for a brief time radiated, make
+the spectacle a most striking one. (See Fig. 56.)
+
+The “pour” is preceded by a shower of sparks, consisting of little
+particles of molten steel which are projected fully a hundred feet in
+the direction of the open mouth of the converter. In the line of this
+my apparatus was stationed in an open window, at a point where its view
+could be directed down into the converter on one side, and up at the
+sun on the other. This apparatus consisted of a long photometer-box
+with a _porte-lumière_ at one end. The mirror of this reflected the
+sun’s rays through the box and then on to the pouring metal, tracing
+their way to it by a beam visible in the dusty air (Fig. 57). In the
+path of this beam was placed the measuring apparatus, both for heat
+and light. As the best point of observation was in the line of the
+blast, a shower of sparks was driven over the instrument and observer
+at every “pour;” and the rain of wet soot from chimneys without, the
+bombardment from within, and the moving masses of red-hot iron around,
+made the experiment an altogether peculiar one. The apparatus was
+arranged in such a way that the effect (except for the absorption of
+its beams on the way) was independent of the size or distance of the
+sun, and depended on the absolute radiation there, and was equivalent,
+in fact, to taking a sample piece of the sun’s face _of equal size_
+with the fluid metal, bringing them face to face, and seeing which
+was the hotter and brighter. The comparison, however, was unfair to
+the sun, because its rays were in reality partly absorbed by the
+atmosphere on the way, while those of the furnace were not. Under these
+circumstances the heat from any single square foot of the sun’s surface
+was found to be _at least_ eighty-seven times that from a square foot
+of the melted metal, while the light from the sun was proved to be,
+foot for foot, over five thousand times that from the molten steel,
+though the latter, separately considered, seemed to be itself, as I
+have said, of quite sunlike brilliancy.
+
+[Illustration: FIG. 57.--PHOTOMETER-BOX.]
+
+We must not conclude from this that the _temperature_ of the sun was
+five thousand times that of the steel, but we may be certain that it
+was at any rate a great deal the higher of the two. It is probable,
+from all experiments made up to this date, that the solar effective
+temperature is not less than 3,000 nor more than 30,000 degrees of
+the centigrade thermometer. Sir William Siemens, whose opinion on any
+question as to heat is entitled to great respect, thought the lower
+value nearer the truth, but this is doubtful.
+
+[Illustration: FIG. 58.--MOUCHOT’S SOLAR ENGINE. (FROM A FRENCH
+PRINT.)]
+
+       *       *       *       *       *
+
+We have, in all that has preceded, been speaking of the sun’s
+constitution and appearance, and have hardly entered on the question
+of its industrial relations to man. It must be evident, however, that
+if we derive, as it is asserted we do, almost all our mechanical power
+from this solar heat,--if our water-wheel is driven by rivers which
+the sun feeds by the rain he sucks up for them into the clouds, if
+the coal is stored sun-power, and if, as Stevenson said, it really is
+the sun which drives our engines, though at second hand,--there is an
+immense fund of possible mechanical power still coming to us from him
+which might be economically utilized. Leaving out of sight all our
+more important relations to him (for, as has been already said, he
+is in a physical sense our creator, and he keeps us alive from hour
+to hour), and considering him only as a possible servant to grind
+our corn and spin our flax, we find that even in this light there
+are startling possibilities of profit in the study of our subject.
+From recent measures it appears that from every square yard of the
+earth exposed perpendicularly to the sun’s rays, in the absence of an
+absorbing atmosphere, there could be derived more than one horse-power,
+if the heat were all converted into this use, and that even on such a
+little area as the island of Manhattan, or that occupied by the city
+of London, the noontide heat is enough, could it all be utilized, to
+drive all the steam-engines in the world. It will not be surprising,
+then, to hear that many practical men are turning their attention to
+this as a source of power, and that, though it has hitherto cost more
+to utilize the power than it is worth, there is reason to believe
+that some of the greatest changes which civilization has to bring
+may yet be due to such investigations. The visitor to the last Paris
+Exposition may remember an extraordinary machine on the grounds of
+the Trocadéro, looking like a gigantic inverted umbrella pointed
+sunward. This was the sun-machine of M. Mouchot, consisting of a great
+parabolic reflector, which concentrated the heat on a boiler in the
+focus and drove a steam-engine with it, which was employed in turn to
+work a printing-press, as our engraving shows (Fig. 58). Because these
+constructions have been hitherto little more than playthings, we are
+not to think of them as useless. If toys, they are the toys of the
+childhood of a science which is destined to grow, and in its maturity
+to apply this solar energy to the use of all mankind.
+
+Even now they are beginning to pass into the region of practical
+utility, and in the form of the latest achievement of Mr. Ericsson’s
+ever-young genius are ready for actual work on an economical scale.
+We present in Fig. 59 his new actually working solar engine, which
+there is every reason to believe is more efficient than Mouchot’s,
+and probably capable of being used with economical advantage in
+pumping water in desert regions of our own country. It is pregnant
+with suggestion of the future, if we consider the growing demand for
+power in the world, and the fact that its stock of coal, though vast,
+is strictly limited, in the sense that when it _is_ gone we can get
+absolutely no more. The sun has been making a little every day for
+millions of years,--so little and for so long, that it is as though
+time had daily dropped a single penny into the bank to our credit for
+untold ages, until an enormous fund had been thus slowly accumulated in
+our favor. We are drawing on this fund like a prodigal who thinks his
+means endless, but the day will come when our check will no longer be
+honored, and what shall we do then?
+
+[Illustration: FIG. 59.--ERICSSON’S NEW SOLAR ENGINE, NOW IN PRACTICAL
+USE IN NEW YORK.]
+
+The exhaustion of some of the coal-beds is an affair of the immediate
+future, by comparison with the vast period of time we have been
+speaking of. The English coal-beds, it is asserted, will, from present
+indications, be quite used up in about three hundred years more.
+
+Three hundred years ago, the sun, looking down on the England of our
+forefathers, saw a fair land of green woods and quiet waters, a land
+unvexed with noisier machinery than the spinning-wheel, or the needles
+of the “free maids that weave their threads with bones.” Because of the
+coal which has been dug from its soil, he sees it now soot-blackened,
+furrowed with railway-cuttings, covered with noisy manufactories,
+filled with grimy operatives, while the island shakes with the throb
+of coal-driven engines, and its once quiet waters are churned by the
+wheels of steamships. Many generations of the lives of men have passed
+to make the England of Elizabeth into the England of Victoria; but what
+a moment this time is, compared with the vast lapse of ages during
+which the coal was being stored! What a moment in the life of the
+“all-beholding sun,” who in a few hundred years--his gift exhausted
+and the last furnace-fire out--may send his beams through rents in the
+ivy-grown walls of deserted factories, upon silent engines brown with
+rust, while the mill-hand has gone to other lands, the rivers are clean
+again, the harbors show only white sails, and England’s “black country”
+is green once more! To America, too, such a time may come, though at a
+greatly longer distance.
+
+Does this all seem but the idlest fancy? That something like it will
+come to pass sooner or later, is a most certain fact--as certain as any
+process of Nature--if we do not find a new source of power; for of the
+coal which has supplied us, after a certain time we can get no more.
+
+Future ages may see the seat of empire transferred to regions of the
+earth now barren and desolated under intense solar heat,--countries
+which, for that very cause, will not improbably become the seat of
+mechanical and thence of political power. Whoever finds the way to
+make industrially useful the vast sun-power now wasted on the deserts
+of North Africa or the shores of the Red Sea, will effect a greater
+change in men’s affairs than any conqueror in history has done; for he
+will once more people those waste places with the life that swarmed
+there in the best days of Carthage and of old Egypt, but under another
+civilization, where man no longer shall worship the sun as a god, but
+shall have learned to make it his servant.
+
+
+
+
+V.
+
+THE PLANETS AND THE MOON.
+
+
+When we look up at the heavens, we see, if we watch through the night,
+the host of stars rising in the east and passing above us to sink
+in the west, always at the same distance and in unchanging order,
+each seeming a point of light as feeble as the glow-worm’s shine in
+the meadow over which they are rising, each flickering as though the
+evening wind would blow it out. The infant stretches out its hand to
+grasp the Pleiades; but when the child has become an old man the “seven
+stars” are still there unchanged, dim only in his aged sight, and
+proving themselves the enduring substance, while it is his own life
+which has gone, as the shine of the glow-worm in the night. They were
+there just the same a hundred generations ago, before the Pyramids were
+built; and they will tremble there still, when the Pyramids have been
+worn down to dust with the blowing of the desert sand against their
+granite sides. They watched the earth grow fit for man long before man
+came, and they will doubtless be shining on when our poor human race
+itself has disappeared from the surface of this planet.
+
+Probably there is no one of us who has not felt this solemn sense of
+their almost infinite duration as compared with his own little portion
+of time, and it would be a worthy subject for our thought if we could
+study them in the light that the New Astronomy sheds for us on their
+nature. But I must here confine myself to the description of but a few
+of their number, and speak, not of the infinite multitude and variety
+of stars, each a self-shining sun, but only of those which move close
+at hand; for it is not true of quite all that they keep at the same
+distance and order.
+
+Of the whole celestial army which the naked eye watches, there are five
+stars which do change their places in the ranks, and these change in
+an irregular and capricious manner, going about among the others, now
+forward and now back, as if lost and wandering through the sky. These
+wanderers were long since known by distinct names, as Mercury, Venus,
+Mars, Jupiter, and Saturn, and believed to be nearer than the others;
+and they are, in fact, companions to the earth and fed like it by the
+warmth of our sun, and like the moon are visible by the sunlight which
+they reflect to us. With the earliest use of the telescope, it was
+found that while the other stars remained in it mere points of light
+as before, these became magnified into disks on which markings were
+visible, and the markings have been found with our modern instruments,
+in one case at least, to take the appearance of oceans and snow-capped
+continents and islands. These, then, are not uninhabitable self-shining
+suns, but worlds, vivified from the same fount of energy that supplies
+us, and the possible abode of creatures like ourselves.
+
+[Illustration: FIG. 60.--SATURN. (FROM A DRAWING BY TROUVELOT).]
+
+“Properly speaking,” it is said, “man is the only subject of interest
+to man;” and if we have cared to study the uninhabitable sun because
+all that goes on there is found to be so intimately related to us,
+it is surely a reasonable curiosity which prompts the question so
+often heard as to the presence of life on these neighbor worlds,
+where it seems at least not impossible that life should exist. Even
+the very little we can say in answer to this question will always be
+interesting; but we must regretfully admit at the outset that it is
+but little, and that with some planets, like Mercury and Venus, the
+great telescopes of modern times cannot do much more than those of
+Galileo, with which our New Astronomy had its beginning.
+
+Let us leave these, then, and pass out to the confines of the planetary
+system, where we may employ our telescopes to better advantage.
+
+The outer planets, Neptune and Uranus, remain pale disks in the most
+powerful instruments, the first attended by a single moon, the second
+by four, barely visible; and there is so very little yet known about
+their physical features, that we shall do better to give our attention
+to one of the most interesting objects in the whole heavens,--the
+planet Saturn, on which we can at any rate see enough to arouse a
+lively curiosity to know more.
+
+When Galileo first turned his glass on Saturn, he saw, as he thought,
+that it consisted of three spheres close together, the middle one
+being the largest. He was not quite sure of the fact, and was in a
+dilemma between his desire to wait longer for further observation, and
+his fear that some other observer might announce the discovery if he
+hesitated. To combine these incompatibilities--to announce it so as to
+secure the priority, and yet not announce it till he was ready--might
+seem to present as great a difficulty as the discovery itself; but
+Galileo solved this, as we may remember, by writing it in the sentence,
+“Altissimum planetam tergeminum observavi” (“I have observed the
+highest planet to be triple”), and then throwing it (in the printer’s
+phrase) “into pi,” or jumbling the letters, which made the sentence
+into the monstrous word
+
+  SMAJSMRMJLMEBOETALEVMJPVNENVGTTAVJRAS,
+
+and publishing _this_, which contained his discovery, but under lock
+and key. He had reason to congratulate himself on his prudence, for
+within two years two of the supposed bodies disappeared, leaving only
+one. This was in 1612; and for nearly fifty years Saturn continued to
+all astronomers the enigma which it was to Galileo, till in 1656 it
+was finally made clear that it was surrounded by a thin flat ring,
+which when seen fully gave rise to the first appearance in Galileo’s
+small telescope, and when seen edgewise disappeared from its view
+altogether. Everything in this part of our work depends on the power
+of the telescope we employ, and in describing the modern means of
+observation we pass over two centuries of slow advance, each decade
+of which has marked some progress in the instrument, to one of its
+completest types, in the great equatorial at Washington, shown in Fig.
+61.
+
+[Illustration: FIG. 61.--THE EQUATORIAL TELESCOPE AT WASHINGTON.]
+
+The revolving dome above, the great tube beneath, its massive piers,
+and all its accessories are only means to carry and direct the great
+lens at the further end, which acts the part of the lens in our own
+eye, and forms the image of the thing to be looked at. Galileo’s
+original lens was a single piece of glass, rather smaller than that of
+our common spectacles; but the lens here is composed of two pieces,
+each twenty-six inches in diameter, and collects as much light as a
+human eye would do if over two feet across. But this is useless if the
+lens is not shaped with such precision as to send every ray to its
+proper place at the eye-piece, nearly thirty-five feet away; and, in
+fact, the shape given its surface by the skilful hands of the Messrs.
+Clark, who made it, is so exquisitely exact that all the light of a
+star gathered by this great surface is packed at the distant focus into
+a circle very much smaller than that made by the dot on this _i_, and
+the same statement may be made of the great Lick glass, which is three
+feet in diameter,--an accuracy we might call incredible were it not
+certain. It is with instruments of such accuracy that astronomy now
+works, and it is with this particular one that some of the observations
+we are going to describe have been made.
+
+In all the heavens there is no more wonderful object than Saturn, for
+it preserves to us an apparent type of the plan on which all the worlds
+were originally made. Let us look at it in this study by Trouvelot
+(Fig. 60). The planet, we must remember, is a globe nearly seventy
+thousand miles in diameter, and the outermost ring is over one hundred
+and fifty thousand miles across, so that the proportionate size of our
+earth would be over-represented here by a pea laid on the engraving.
+The belts on the globe show delicate tints of brown and blue, and parts
+of the ring are, as a whole, brighter than the planet; but this ring,
+as the reader may see, consists of at least three main divisions, each
+itself containing separate features. First is the gray outer ring, then
+the middle one, and next the curious “crape” ring, very much darker
+than the others, looking like a belt where it crosses the planet,
+and apparently feebly transparent, for the outline of the globe has
+been seen (though not very distinctly) _through_ it. The whole system
+of rings is of the most amazing thinness, for it is probably thinner
+in proportion to its size than the paper on which this is printed is
+to the width of the page; and when it is turned edgewise to us, it
+disappears to all but the most powerful telescopes, in which it looks
+then like the thinnest conceivable line of light, on which the moons
+have been seen projected, appearing like beads sliding along a golden
+wire. The globe of the planet casts on the ring a shadow, which is
+here shown as a broken line, as though the level of the rings were
+suddenly disturbed. At other times (as in a beautiful drawing made with
+the same instrument by Professor Holden) the line seems continuous,
+though curved as though the middle of the ring system were thicker
+than the edge. The rotation of the ring has been made out by direct
+observations; and the whole is in motion about the globe,--a motion
+so smooth and steady that there is no flickering in the shadow “where
+Saturn’s steadfast shade sleeps on its luminous ring.”
+
+[Illustration: FIG. 62.--JUPITER, MOON, AND SHADOW. (BY PERMISSION OF
+WARREN DE LA RUE.)]
+
+What is it? No solid could hold together under such conditions; we can
+hardly admit the possibility of its being a liquid film extended in
+space; and there are difficulties in admitting it to be gaseous. But if
+not a solid, a liquid, or a gas, again what can it be? It was suggested
+nearly two centuries ago that the ring might be composed of innumerable
+little bodies like meteorites, circling round the globe so close
+together as to give the appearance we see, much as a swarm of bees at
+a distance looks like a continuous cloud; and this remains the most
+plausible solution of what is still in some degree a mystery. Whatever
+it be, we see in the ring the condition of things which, according
+to the nebular hypothesis, once pertained to all the planets at a
+certain stage of their formation; and this, with the extraordinary
+lightness of the globe (for the whole planet would float on water),
+makes us look on it as still in the formative stage of uncondensed
+matter, where the solid land as yet is not, and the foot could find
+no resting-place. Astrology figured Saturn as “spiteful and cold,--an
+old man melancholy;” but if we may indulge such a speculation, modern
+astronomy rather leads us to think of it as in the infancy of its
+life, with every process of planetary growth still in its future, and
+separated by an almost unlimited stretch of years from the time when
+life under the conditions in which we know it can even begin to exist.
+
+       *       *       *       *       *
+
+Like this appears also the condition of Jupiter (Fig. 62), the
+greatest of the planets, whose globe, eighty-eight thousand miles in
+diameter, turns so rapidly that the centrifugal force causes a visible
+flattening. The belts which stretch across its disk are of all delicate
+tints--some pale blue, some of a crimson lake; a sea-green patch has
+been seen, and at intervals of late years there has been a great oval
+red spot, which has now nearly gone, and which our engraving does not
+show. The belts are largely, if not wholly, formed of rolling clouds,
+drifting and changing under our eyes, though more rarely a feature
+like the oval spot just mentioned will last for years, an enduring
+enigma. The most recent observations tend to make us believe that the
+equatorial regions of Jupiter, like those of the sun, make more turns
+in a year than the polar ones; while the darkening toward the edge is
+another sunlike feature, though perhaps due to a distinct cause, and
+this is beautifully brought out when any one of the four moons which
+circle the planet passes between us and its face, an occurrence also
+represented in our figure. The moon, as it steals on the comparatively
+dark edge, shows us a little circle of an almost lemon-yellow, but the
+effect of contrast grows less as it approaches the centre. Next (or
+sometimes before), the disk is invaded by a small and intensely black
+spot, the shadow of the moon, which slides across the planet’s face,
+the transit lasting long enough for us to see that the whole great
+globe, serving as a background for the spectacle, has visibly revolved
+on its axis since we began to gaze. Photography, in the skilful hands
+of the late Professor Henry Draper, gave us reason to suspect the
+possibility that a dull light is sent to us from parts of the planet’s
+surface besides what it reflects, as though it were still feebly
+glowing like a nearly extinguished sun; and, on the whole, a main
+interest of these features to us lies in the presumption they create
+that the giant planet is not yet fit to be the abode of life, but is
+more probably in a condition like that of our earth millions of years
+since, in a past so remote that geology only infers its existence, and
+long before our own race began to be. That science, indeed, itself
+teaches us that such all but infinite periods are needed to prepare a
+planet for man’s abode, that the entire duration of his race upon it is
+probably brief in comparison.
+
+       *       *       *       *       *
+
+We pass by the belt of asteroids, and over a distance many times
+greater than that which separates the earth from the sun, till we
+approach our own world. Here, close beside it as it were, in comparison
+with the enormous spaces which intervene between it and Saturn and
+Jupiter, we find a planet whose size and features are in striking
+contrast to those of the great globe we have just quitted. It is Mars,
+which shines so red and looks so large in the sky because it is so
+near, but whose diameter is only about half that of our earth. This is
+indeed properly to be called a neighbor world, but the planetary spaces
+are so immense that this neighbor is at closest still about thirty-four
+million miles away.
+
+[Illustration: FIG 63.--THREE VIEWS OF MARS.]
+
+[Illustration: FIG 64.--MAP OF MARS.]
+
+Looking across that great gulf, we see in our engraving (Fig.
+63)--where we have three successive views taken at intervals of a few
+hours--a globe not marked by the belts of Jupiter or Saturn, but with
+outlines as of continents and islands, which pass in turn before our
+eyes as it revolves in a little over twenty-four and a half of our
+hours, while at either pole is a white spot. Sir William Herschel was
+the first to notice that this spot increased in size when it was turned
+away from the sun, and diminished when the solar heat fell on it; so
+that we have what is almost proof that here is ice (and consequently
+water) on another world. Then, as we study more, we discern forms which
+move from day to day on the globe apart from its rotation, and we
+recognize in them clouds sweeping over the surface,--not a surface of
+still other clouds below, but of what we have good reason to believe to
+be land and water.
+
+By the industry of numerous astronomers, seizing every favorable
+opportunity when Mars comes near, so many of these features have been
+gathered that we have been enabled to make fairly complete maps of the
+planet, one of which by Mr. Green is here given (Fig. 64).
+
+Here we see the surface more diversified than that of our earth,
+while the oceans are long, narrow, canal-like seas, which everywhere
+invade the land, so that on Mars one could travel almost everywhere by
+water. These canals seem also in some cases to exist in pairs or to be
+remarkably duplicated. The spectroscope indicates water-vapor in the
+Martial atmosphere, and some of the continents, like “Lockyer Land,”
+are sometimes seen white, as though covered with ice: while one island
+(marked on our map as Hall Island) has been seen so frequently thus,
+that it is very probable that here some mountain or tableland rises
+into the region of perpetual snow.
+
+The cause of the red color of Mars has never been satisfactorily
+ascertained. Its atmosphere does not appear to be dark enough to
+produce such an effect, and perhaps as probable an explanation as any
+is one the suggestion of which is a little startling at first. It is
+that vegetation on Mars may be _red_ instead of green! There is no
+intrinsic improbability in the idea, for we are even to-day unprepared
+to say with any certainty why vegetation is green here, and it is quite
+easy to conceive of atmospheric conditions which would make red the
+best absorber of the solar heat. Here, then, we find a planet on which
+we obtain many of the conditions of life which we know ourselves, and
+here, if anywhere in the system, we may allowably inquire for evidence
+of the presence of something like our own race; but though we may
+indulge in supposition, there is unfortunately no prospect that with
+any conceivable improvement in our telescopes we shall ever obtain
+anything like certainty. We cannot assert that there are any bounds to
+man’s invention, or that science may not, by some means as unknown to
+us as the spectroscope was to our grandfathers, achieve what now seems
+impossible; but to our present knowledge no such means exist, though we
+are not forbidden to look at the ruddy planet with the feeling that it
+may hold possibilities more interesting to our humanity than all the
+wonders of the sun, and all the uninhabitable immensities of his other
+worlds.
+
+Before we leave Mars, we may recall to the reader’s memory the
+extraordinary verification of a statement made about it more than a
+hundred years ago. We shall have for a moment to leave the paths of
+science for those of pure fiction, for the words we are going to quote
+are those of no less a person than our old friend Captain Gulliver,
+who, after his adventures with the Lilliputians, went to a flying
+island inhabited largely by astronomers. If the reader will take down
+his copy of Swift, he will find in this voyage of Gulliver’s to Laputa
+the following imaginary description of what its imaginary astronomers
+saw:--
+
+  “They have likewise discovered two lesser stars or satellites
+  which revolve about Mars, whereof the innermost is distant from
+  the centre of the primary planet exactly three of its diameters,
+  and the outermost five; the former revolves in the space of ten
+  hours, and the latter in twenty-one and a half.”
+
+Now, compare this passage, which was published in the year 1727, with
+the announcement in the scientific journals of August, 1877 (a hundred
+and fifty years after), that two moons did exist, and had just been
+discovered by Professor Hall, of Washington, with the great telescope
+of which a drawing has been already given. The resemblance does not end
+even here, for Swift was right also in describing them as very near the
+planet and with very short periods, the actual distances being about
+one and a half and seven diameters, and the actual times about eight
+and thirty hours respectively,--distances and periods which, if not
+exactly those of Swift’s description, agree with it in being less than
+any before known in the solar system. It is certain that there could
+not have been the smallest ground for a suspicion of their existence
+when “Gulliver’s Travels” was written, and the coincidence--which is
+a pure coincidence--certainly approaches the miraculous. We can no
+longer, then, properly speak of “the snowy poles of moonless Mars,”
+though it does still remain moonless to all but the most powerful
+telescopes in the world, for these bodies are the very smallest known
+in the system. They present no visible disks to measure, but look
+like the faintest of points of light, and their size is only to be
+guessed at from their brightness. Professor Pickering has carried on
+an interesting investigation of them. His method depended in part on
+getting holes of such smallness made in a plate of metal that the light
+coming through them would be comparable with that of the Martial moons
+in the telescope. It was found almost impossible to command the skill
+to make these holes small enough, though one of the artists employed
+had already distinguished himself by drilling a hole through a fine
+cambric needle _lengthwise_, so as to make a tiny steel tube of it.
+When the difficulty was at last overcome, the satellites were found to
+be less than ten miles in diameter, and a just impression both of their
+apparent size and light may be gathered from the statement that either
+roughly corresponds to that which would be given by a human hand held
+up at Washington, and viewed from Boston, Massachusetts, a distance of
+four hundred miles.
+
+We approach now the only planet in which man is certainly known to
+exist, and which ought to have an interest for us superior to any which
+we have yet seen, for it is our own. We are voyagers on it through
+space, it has been said, as passengers on a ship, and many of us have
+never thought of any part of the vessel but the cabin where we are
+quartered. Some curious passengers (these are the geographers) have
+visited the steerage, and some (the geologists) have looked under the
+hatches, and yet it remains true that those in one part of our vessel
+know little, even now, of their fellow-voyagers in another. How much
+less, then, do most of us know of the ship itself, for we were all born
+on it, and have never once been off it to view it from the outside!
+
+No world comes so near us in the aerial ocean as the moon; and if we
+desire to view our own earth as a planet, we may put ourselves in fancy
+in the place of a lunar observer. “Is it inhabited?” would probably
+be one of the first questions which he would ask, if he had the same
+interest in us that we have in him; and the answer to this would call
+out all the powers of the best telescopes such as we possess.
+
+An old author, Fontenelle, has put in the mouth of an imaginary
+spectator a lively description of what would be visible in twenty-four
+hours to one looking down on the earth as it turned round beneath him.
+“I see passing under my eyes,” he says, “all sorts of faces,--white and
+black and olive and brown. Now it’s hats, and now turbans, now long
+locks and then shaven crowns; now come cities with steeples, next more
+with tall, crescent-capped minarets, then others with porcelain towers;
+now great desolate lands, now great oceans, then dreadful deserts,--in
+short, all the infinite variety the earth’s surface bears.” The truth
+is, however, that, looking at the earth from the moon, the largest
+moving animal, the whale or the elephant, would be utterly beyond our
+ken; and it is questionable whether the largest ship on the ocean
+would be visible, for the popular idea as to the magnifying power
+of great telescopes is exaggerated. It is probable that under any
+but extraordinary circumstances our lunar observer, with our best
+telescopes, could not bring the earth within less than an apparent
+distance of five hundred miles; and the reader may judge how large a
+moving object must be to be seen, much less recognized, by the naked
+eye at such a distance.
+
+Of course, a chief interest of the supposition we are making lies in
+the fact that it will give us a measure of our own ability to discover
+evidences of life in the moon, if there are any such as exist here; and
+in this point of view it is worth while to repeat, that scarcely any
+temporary phenomenon due to human action could be even telescopically
+visible from the moon under the most favoring circumstances. An army
+such as Napoleon led to Russia might conceivably be visible if it moved
+in a dark solid column across the snow. It is barely possible that such
+a vessel as one of the largest ocean steamships might be seen, under
+very favorable circumstances, as a moving dot; and it is even quite
+probable that such a conflagration as the great fire of Chicago would
+be visible in the lunar telescope, as something like a reddish star on
+the night side of our planet; but this is all in this sort that could
+be discerned.
+
+By making minute maps, or, still better, photographs, and comparing
+one year with another, much however might have been done by our lunar
+observer during this century. In its beginning, in comparison to the
+vast forests which then covered the North American continent, the
+cultivated fields along its eastern seaboard would have looked to him
+like a golden fringe bordering a broad mantle of green; but now he
+would see that the golden fringe has encroached upon the green farther
+back than the Mississippi, and he would gather his best evidence of
+change from the fact (surely a noteworthy one) that the people of
+the United States have altered the features of the world during the
+present century to a degree visible in another planet!
+
+Our observer would probably be struck by the moving panorama of
+forests, lakes, continents, islands, and oceans, successively gliding
+through the field of view of his telescope as the earth revolved;
+but, travelling along beside it on his lunar station, he would hardly
+appreciate its actual flight through space, which is an easy thing to
+describe in figures, and a hard one to conceive. If we look up at the
+clock, and as we watch the pendulum recall that we have moved about
+nineteen miles at every beat, or in less than three minutes, over a
+distance greater than that which divides New York from Liverpool, we
+still probably but very imperfectly realize the fact that (dropping
+all metaphor) the earth is really a great projectile, heavier than the
+heaviest of her surface rocks, and traversing space with a velocity of
+over sixty times that of the cannon-ball. Even the firing of a great
+gun with a ball weighing one or two hundred pounds is, to the novice at
+least, a striking spectacle. The massive iron sphere is hoisted into
+the gun, the discharge comes, the ground trembles, and, as it seems,
+almost in the same instant, a jet rises where the ball has touched the
+water far away. The impression of immense velocity and of a resistless
+capacity of destruction in that flying mass is irresistible, and
+justifiable too: but what is this ball to that of the earth, which is
+a globe counting eight thousand miles in diameter, and weighing about
+six thousand millions of millions of millions of tons; which, if our
+cannon-ball were flying ahead a mile in advance of its track, would
+overtake it in less than the tenth part of a second; and which carries
+such a potency of latent destruction and death in this motion, that if
+it were possible instantly to arrest it, then, in that instant, “earth
+and all which it inherits would dissolve” and pass away in vapor?
+
+Our turning sphere is moving through what seems to be all but an
+infinite void, peopled only by wandering meteorites, and where warmth
+from any other source than the sun can scarcely be said to exist; for
+it is important to observe that whether the interior be molten or
+not, we get next to no heat from it. The cold of outer space can only
+be estimated in view of recent observations as at least four hundred
+degrees Fahrenheit below zero (mercury freezes at thirty-nine degrees
+below), and it is the sun which makes up the difference of all these
+lacking hundreds of degrees to us, but indirectly, and not in the way
+that we might naturally think, and have till very lately thought; for
+our atmosphere has a great deal to do with it beside the direct solar
+rays, allowing more to come in than to go out, until the temperature
+rises very much higher than it would were there no air here. Thus,
+since it is this power in the atmosphere of storing the heat which
+makes us live, no less than the sun’s rays themselves, we see how the
+temperature of a planet may depend on considerations quite beside its
+distance from the sun; and when we discuss the possibility of life in
+other worlds, we shall do well to remember that Saturn may be possibly
+a warm world, and Mercury conceivably a cold one.
+
+We used to be told that this atmosphere extended forty-five miles above
+us, but later observation proves its existence at a height of many
+times this; and a remarkable speculation, which Dr. Hunt strengthens
+with the great name of Newton, even contemplates it as extending in
+ever-increasing tenuity until it touches and merges in the atmosphere
+of other worlds.
+
+[Illustration: FIG. 65.--THE MOON.
+
+(FROM A PHOTOGRAPH BY L. M. RUTHERFURD, 1873, PUBLISHED BY O. G.
+MASON.)]
+
+But if we begin to talk of things new and old which interest us in our
+earth as a planet, it is hard to make an end. Still we may observe
+that it is the very familiarity of some of these which hinders us from
+seeing them as the wonders they really are. How has this familiarity,
+for instance, made commonplace to us not only the wonderful fact that
+the fields and forests, and the apparently endless plain of earth and
+ocean, are really parts of a great globe which is turning round
+(for this rotation we all are familiar with), but the less appreciated
+miracle that we are all being hurled through space with an immensely
+greater speed than that of the rotation itself. It needs the vision
+of a poet to see this daily miracle with new eyes; and a great poet
+has described it for us, in words which may vivify our scientific
+conception. Let us recall the prologue to “Faust,” where the archangels
+are praising the works of the Lord, and looking at the earth, not as we
+see it, but down on it, from heaven, as it passes by, and notice that
+it is precisely this miraculous swiftness, so insensible to us, which
+calls out an angel’s wonder.
+
+    “And swift and swift beyond conceiving
+    The splendor of the world goes round,
+    Day’s Eden-brightness still relieving
+    The awful Night’s intense profound.
+    The ocean tides in foam are breaking,
+    Against the rocks’ deep bases hurled,
+    And both, the spheric race partaking,
+    Eternal, swift, are onward whirled.”[5]
+
+    [5] Bayard Taylor’s translation.
+
+So, indeed, might an angel see it and describe it!
+
+       *       *       *       *       *
+
+We may have been already led to infer that there is a kind of evolution
+in the planets’ life, which we may compare, by a not wholly fanciful
+analogy, to ours; for we have seen worlds growing into conditions
+which may fit them for habitability, and again other worlds where we
+may surmise, or may know, that life has come. To learn of at least one
+which has completed the analogy, by passing beyond this term to that
+where all life has ceased, we need only look on the moon.
+
+       *       *       *       *       *
+
+The study of the moon’s surface has been continued now from the time
+of Galileo, and of late years a whole class of competent observers has
+been devoted to it, so that astronomers engaged in other branches have
+oftener looked on this as a field for occasional hours of recreation
+with the telescope than made it a constant study. I can recall one or
+two such hours in earlier observing days, when, seated alone under
+the overarching iron dome, the world below shut out, and the world
+above opened, the silence disturbed by no sound but the beating of the
+equatorial clock, and the great telescope itself directed to some hill
+or valley of the moon, I have been so lost in gazing that it seemed as
+though a look through this, the real magic tube, had indeed transported
+me to the surface of that strange alien world. Fortunately for us, the
+same spectacle has impressed others with more time to devote to it and
+more ability to render it, so that we not only have most elaborate
+maps of the moon for the professional astronomer, but abundance of
+paintings, drawings, and models, which reproduce the appearance of
+its surface as seen in powerful telescopes. None of the latter class
+deserves more attention than the beautiful studies of Messrs. Nasmyth
+and Carpenter, who prepared at great labor very elaborate and, in
+general, very faithful models of parts of its surface, and then had
+them photographed under the same illumination which fell on the
+original; and I wish to acknowledge here the special indebtedness of
+this part of what I have to lay before the reader to their work, from
+which the following illustrations are chiefly taken.
+
+Let us remember that the moon is a little over twenty-one hundred miles
+in diameter; that it weighs, bulk for bulk, about two-thirds what the
+earth does, so that, in consequence of this and its smaller size, its
+total weight is only about one-eightieth of that of our globe; and
+that, the force of gravity at its surface being only one-sixth what it
+is here, eruptive explosions can send their products higher than in our
+volcanoes. Its area is between four and five times that of the United
+States, and its average distance is a little less than two hundred and
+forty thousand miles.
+
+[Illustration: FIG. 66.--THE FULL MOON.]
+
+This is very little in comparison with the great spaces we have been
+traversing in imagination; but it is absolutely very large, and across
+it the valleys and mountains of this our nearest neighbor disappear,
+and present to the naked eye only the vague lights and shades known to
+us from childhood as “the man in the moon,” and which were the puzzle
+of the ancient philosophers, who often explained them as reflections
+of the earth itself, sent back to us from the moon as from a mirror.
+It, at any rate, shows that the moon always turns the same face toward
+us, since we always see the same “man,” and that there must be a back
+to the moon which we never behold at all; and, in fact, nearly half of
+this planet does remain forever hidden from human observation.
+
+The “man in the moon” disappears when we are looking in a telescope,
+because we are then brought so near to details that the general
+features are lost; but he can be seen in any photograph of the full
+moon by viewing it at a sufficient distance, and making allowance for
+the fact that the contrasts of light and shade appear stronger in the
+photograph than they are in reality. If the small full moon given in
+Fig. 66, for instance, be looked at from across a room, the naked-eye
+view will be recovered, and its connection with the telescopic ones
+better made out. The best time for viewing the moon, however, is not
+at the full, but at the close of the first quarter; for then we see,
+as in this beautiful photograph (Fig. 65) by Mr. Rutherfurd, that the
+sunlight, falling slantingly on it, casts shadows which bring out all
+the details so that we can distinguish many of them even here,--this
+photograph, though much reduced, giving the reader a better view than
+Galileo obtained with his most powerful telescope. The large gray
+expanse in the lower part is the Mare Serenitatis, that on the left the
+Mare Crisium, and so on; these “seas,” as they were called by the old
+observers, being no seas at all in reality, but extended plains which
+reflect less light than other portions, and which with higher powers
+show an irregular surface. Most of the names of the main features of
+the lunar surface were bestowed by the earlier observers in the infancy
+of the telescope, when her orb
+
+    “Through optic glass the Tuscan artist ‘viewed’
+    At evening from the top of Fiesole
+    Or in Valdarno, to descry new lands,
+    Rivers, or mountains in her spotty globe.”
+
+Mountains there are, like the chain of the lunar Apennines, which the
+reader sees a little below the middle of the moon, and to the right
+of the Mare Serenitatis, and where a good telescope will show several
+thousand distinct summits. Apart from the mountain chains, however, the
+whole surface is visibly pitted with shallow, crater-like cavities,
+which vary from over a hundred miles in diameter to a few hundred yards
+or less, and which, we shall see later, are smaller sunken plains
+walled about with mountains or hills.
+
+One of the most remarkable, of these is Tycho, here seen on the
+photograph of the full moon (Fig. 66), from which radiating streaks go
+in all directions over the lunar surface. These streaks are a feature
+peculiar to the moon (at least we know of nothing to which they can be
+compared on the earth), for they run through mountain and valley for
+hundreds of miles without any apparent reference to the obstacles in
+their way, and it is clear that the cause is a deep-seated one. This
+cause is believed by our authors to be the fact that the moon was once
+a liquid sphere over which a hard crust formed, and that in subsequent
+time the expansion of the interior before solidification cracked the
+shell as we see. The annexed figure (Fig. 67) is furnished by them to
+illustrate their theory, and to show the effects of what they believe
+to be an analogous experiment, _in minimis_, to what Nature has
+performed on the grandest scale; for the photograph shows a glass globe
+actually cracked by the expansion of an enclosed fluid (in this case
+water), and the resemblance of the model to the photograph of the full
+moon on page 141 is certainly a very interesting one.
+
+[Illustration: FIG. 67.--GLASS GLOBE, CRACKED.]
+
+We are able to see from this, and from the multitude of craters shown
+even on the general view, where the whole face of our satellite is
+pit-marked, that eruptive action has been more prominent on the moon in
+ages past than on our own planet, and we are partly prepared for what
+we see when we begin to study it in detail.
+
+We may select almost any part of the moon’s surface for this nearer
+view, with the certainty of finding something interesting. Let us
+choose, for instance, on the photograph of the half-full moon (Fig.
+65), the point near the lower part of the Terminator (as the line
+dividing light from darkness is called) where a minute sickle of light
+seems to invade the darkness, and let us apply in imagination the power
+of a large telescope to it. We are brought at once considerably within
+a thousand miles of the surface, over which we seem to be suspended,
+everything lying directly beneath us as in a bird’s-eye view, and what
+we see is the remarkable scene shown in Fig. 68.
+
+We have before us such a wealth of detail that the only trouble is
+to choose what to speak of where every point has something to demand
+attention, and we can only give here the briefest reference to the
+principal features. The most prominent of these is the great crater
+“Plato,” which lies in the lower right-hand part of the cut. It will
+give the reader an idea of the scale of things to state that the
+diameter of its ring is about seventy miles; so that he will readily
+understand that the mountains surrounding it may average five to six
+thousand feet in height, as they do. The sun is shining from the left,
+and, being low, casts long shadows, so that the real forms of the
+mountains on one side are beautifully indicated by these shadows, where
+they fall on the floor of the crater. In the lower part of the mountain
+wall there has been a land-slide, as we see by the fragments that have
+rolled down into the plain, and of which a trace can be observed in our
+engraving. The whole is quite unlike most terrestrial craters, however,
+not only in its enormous size, but in its proportions; for the floor
+is not precipitous, but flat, or partaking of the general curvature of
+the lunar surface, which it sinks but little below. I have watched with
+interest in the telescope streaks and shades on the floor of Plato, not
+shown in our cut; for here some have suspected evidences of change,
+and fancied a faint greenish tint, as if due to vegetation, but it is
+probably fancy only. Notice the number of small craters around the
+big one, and everywhere on the plate, and then look at the amazingly
+rugged and tumbled mountain heaps on the left (the lunar Alps), cut
+directly through by a great valley (the valley of the Alps), which is
+at the bottom about six miles wide and extraordinarily flat,--flatter
+and smoother even than our engraving shows it, and looking as though
+a great engineering work, rather than an operation of Nature, were in
+question. Above this the mountain shadows are cast upon a wide plain,
+in which are both depressed pits with little mountain (or rather hill)
+rings about them, and extraordinary peaks, one of which, Pico (above
+the great crater), starts up abruptly to the height of eight thousand
+feet, a lunar Matterhorn.
+
+If Mars were as near as the moon, we should see with the naked eye
+clouds passing over its face; and that we never do see these on the
+moon, even with the telescope, is itself a proof that none exist there.
+Now, this absence of clouds, or indeed of any evidence of moisture,
+is confirmed by every one of the nearer views like those we are here
+getting. We might return to this region with the telescope every month
+of our lives without finding one indication of vapor, of moisture, or
+even of air; and from a summit like Pico, could we ascend it, we should
+look out on a scene of such absolute desolation as probably no
+earthly view could parallel. If, as is conceivable, these plains were
+once covered with verdure, and the abode of living creatures, verdure
+and life exist here no longer, and over all must be the silence of
+universal death. But we must leave it for another scene.
+
+[Illustration: FIG. 68.--PLATO AND THE LUNAR ALPS.]
+
+South of Plato extends for many hundred miles a great plain, which
+from its smoothness was thought by the ancient observers to be water,
+and was named by them the “Imbrian Sea,” and this is bounded on the
+south and west by a range of mountains--the “lunar Apennines” (Fig.
+69)--which are the most striking on our satellite. They are visible
+even with a spy-glass, looking then like bread-crumbs ranged upon a
+cloth, while with a greater power they grow larger and at the same
+time more chaotic. As we approach nearer, we see that they rise
+with a comparatively gradual slope, to fall abruptly, in a chain of
+precipices that may well be called tremendous, down to the plain below,
+across which their shadows are cast. Near their bases are some great
+craters of a somewhat different type from Plato, and our illustration
+represents an enlarged view of a part of this Apennine chain, of the
+great crater Archimedes, and of its companions Aristillus and Autolycus.
+
+Our engraving will tell, more than any description, of the contrast
+of the tumbled mountain peaks with the level plain from which they
+spring,--a contrast for which we have scarcely a terrestrial parallel,
+though the rise of the Alps from the plains of Lombardy may suggest an
+inadequate one. The Sierra Nevadas of California climb slowly up from
+the coast side, to descend in great precipices on the east, somewhat
+like this; but the country at their feet is irregular and broken, and
+their highest summits do not equal those before us, which rise to
+seventeen or eighteen thousand feet, and from one of which we should
+look out over such a scene of desolation as we can only imperfectly
+picture to ourselves from any experience of a terrestrial desert. The
+curvature of the moon’s surface is so much greater than ours, that it
+would hide the spurs of hills which buttress the southern slopes of
+Archimedes, leaving only the walls of the great mountain ring visible
+in the extremest horizon, while between us and them would extend what
+some still maintain to have been the bed of an ancient lunar ocean,
+though assuredly no water exists there now.
+
+Among the many fanciful theories to account for the forms of the
+ringed plains, one (and this is from a man of science whose ideas are
+always original) invokes the presence of water. According to it, these
+great plains were once ocean beds, and in them worked a coral insect,
+building up lunar “atolls” and ring-shaped submarine mountains, as the
+coral polyp does here. The highest summits of the great rings thus
+formed were then low islands, just “a-wash” with the waves of the
+ancient lunar sea, and, for aught we know, green with feathery palms.
+Then came (in the supposition in question) a time when the ocean dried
+up, and the mountains were left standing, as we see, in rings, after
+the cause of their formation was gone. If it be asked where the water
+went to, the answer is not very obvious on the old theories; but those
+who believe in them point to the extraordinary cracks in the soil, like
+those our engraving shows, as chasms and rents, by which the vanished
+seas, and perhaps also the vanished air, have been absorbed into the
+interior.
+
+[Illustration: FIG. 69.--THE LUNAR APENNINES: ARCHIMEDES.]
+
+If there was indeed such an ancient ocean, it would have washed the
+very feet of the precipices on whose summits we are in imagination
+standing, and below us their recesses would have formed harbors which
+fancy might fill with commerce, and cities in which we might picture
+life and movement where all is now dead. It need hardly be said that
+no telescope has ever revealed their existence (if such ruins, indeed,
+there are), and it may be added that the opinion of geologists is, as
+a whole, unfavorable to the presence of water on the moon, even in
+the past, from the absence of any clear evidence of erosive action;
+but perhaps we are not yet entitled to speak on these points with
+certainty, and are not forbidden to believe that water may have existed
+here in the past by any absolute testimony to the contrary. The views
+of those who hold the larger portion of the lunar craters to have
+been volcanic in their formation are far more probable; and perhaps
+as simple an evidence of the presumption in their favor as we can
+give is directly to compare such a lunar region as this, the picture
+of which was made for us from a model, with a similar model made from
+some terrestrial volcanic region. Here (Fig. 70) is a photograph of
+such a modelled plan of the country round the Bay of Naples, showing
+the ancient crater of Vesuvius and its central cone, with other and
+smaller craters along the sea. Here, of course, we _know_ that the
+forms originated in volcanic action, and a comparison of them with our
+moon-drawing is most interesting. To return to our Apennine region
+(Fig. 69), we must admit, however, when we consider the vast size of
+these things (Archimedes is fifty miles in diameter), that they are
+very different in proportion from our terrestrial craters, and that
+numbers of them present no central cone whatever; so that if some of
+them seem clearly eruptive, there are others to which we have great
+difficulties in making these volcanic theories apply. Let us look, for
+instance, at still another region (Fig. 71). It lies rather above the
+centre of the full moon, and may be recognized also on the Rutherfurd
+photograph; and it consists of the group of great ring-plains, three of
+which form prominent figures in our cut.
+
+Ptolemy (the lower of these in the drawing) is an example of such a
+plain, whose diameter reaches to about one hundred and fifteen miles,
+so that it encloses an area of nearly eight thousand square miles
+(or about that of the State of Massachusetts), within which there is
+no central cone or point from which eruptive forces appear to have
+acted, except the smaller craters it encloses. On the south we see
+a pass in the mountain wall opening into the neighboring ring-plain
+of Alphonsus, which is only less in size; and south of this again is
+Arzachel, sixty-six miles in diameter, surrounded with terraced walls,
+rising in one place to a height greater than that of Mont Blanc, while
+the central cone is far lower. The whole of the region round about,
+though not the roughest on the moon, is rough and broken in a way
+beyond any parallel here, and which may speak for itself; but perhaps
+the most striking of the many curious features--at least the only one
+we can pause to examine--is what is called “The Railway,” an almost
+perfectly straight line, on one side of which the ground has abruptly
+sunk, leaving the undisturbed part standing like a wall, and forming a
+“fault,” as geologists call it. This is the most conspicuous example of
+its kind in the moon, but it is only one of many evidences that we are
+looking at a world whose geological history has been not wholly unlike
+our own. But the moon contains, as has been said, but the one-eightieth
+part of the mass of our globe, and has therefore cooled with much
+greater rapidity, so that it has not only gone through the epochs
+of our own past time, but has in all probability already undergone
+experiences which for us lie far in the future; and it is hardly less
+than justifiable language to say that we are beholding here in some
+respects what the face of our world may be when ages have passed away.
+
+[Illustration: FIG. 70.--VESUVIUS AND NEIGHBORHOOD OF NAPLES.]
+
+To see this more clearly, we may consider that in general we find that
+the early stages of cosmical life are characterized by great heat; a
+remark of the truth of which the sun itself furnishes the first and
+most obvious illustration. Then come periods which we appear to have
+seen exemplified in Jupiter, where the planet is surrounded by volumes
+of steam-like vapor, through which we may almost believe we recognize
+the dull glow of not yet extinguished fires; then times like those
+which our earth passed through before it became the abode of man;
+and then the times in which human history begins. But if this process
+of the gradual loss of heat go on indefinitely, we must yet come to
+still another era, when the planet has grown too cold to support life,
+as it was before too hot; and this condition, in the light of some very
+recent investigations, it seems probable we have now before us on the
+moon.
+
+We have, it is true, been taught until very lately that the side of the
+moon turned sunward would grow hotter and hotter in the long lunar day,
+till it reached a temperature of two hundred to three hundred degrees
+Fahrenheit, and that in the equally long lunar night it would fall as
+much as this below zero. But the evidence which was supposed to support
+this conclusion as to the heat of the lunar day is not supported by
+recent experiments of the writer; and if these be trustworthy, certain
+facts appear to him to show that the temperature of the moon’s surface,
+even under full perpetual sunshine, must be low,--and this because
+of the absence of air there to keep the stored sun-heat from being
+radiated away again into space.
+
+As we ascend the highest terrestrial mountains, and get partly above
+our own protecting blanket of air, things do not grow hotter and
+hotter, but colder and colder; and it seems contrary to the teachings
+of common sense to believe that if we could ascend higher yet, where
+the air ceases altogether, we should not find that it grew colder
+still. But this last condition (of airlessness) is the one which does
+prevail beyond a doubt in the moon, on whose whole surface, then, there
+must be (unless there are sources of internal heat of which we know
+nothing) conditions of temperature which are an exaggeration of those
+we experience on the summit of a very lofty mountain, where we have the
+curious result that the skin may be burned under the solar rays, while
+we are shivering at the same time in what the thermometer shows is an
+arctic cold.
+
+We have heard of this often; but a personal experience so impressed the
+fact on me that I will relate it for the benefit of the reader, who
+may wish to realize to himself the actual conditions which probably
+exist in the airless lunar mountains and plains we are looking at.
+He cannot go there; but he may go if he pleases, as I have done, to
+the waterless, shadeless waste which stretches at the eastern slope
+of the Sierra Nevadas (a chain almost as high and steep as the lunar
+Apennines), and live some part of July and August in this desert, where
+the thermometer rises occasionally to one hundred and ten degrees in
+the shade, and his face is tanned till it can tan no more, and he
+appears to himself to have experienced the utmost in this way that the
+sun can do.
+
+The sky is cloudless, and the air so clear that all idea of the real
+distance and size of things is lost. The mountains, which rise in
+tremendous precipices above him, seem like moss-covered rocks close
+at hand, on the tops of which, here and there, a white cloth has been
+dropped; but the “moss” is great primeval forests, and the white cloths
+large isolated snow-fields, tantalizing the dweller in the burning
+desert with their delusive nearness. When I climbed the mountains,
+at an altitude of ten thousand feet I already found the coolness
+delicious, but at the same time (by the strange effect I have been
+speaking of) the skin began to burn, as though the seasoning in the
+desert counted for nothing at all; and as the air grew thinner and
+thinner while I mounted still higher and higher, though the thermometer
+fell, every part of the person exposed to the solar rays presented the
+appearance of a recent severe burn from an actual fire,--and a really
+severe burn it was, as I can testify,--and yet all the while around us,
+under this burning sun and cloudless sky, reigned a perpetual winter
+which made it hard to believe that torrid summer still lay below. The
+thinner the air, then, the colder it grows, even where we are exposed
+to the sun, and the lower becomes the reading of the thermometer.
+Now, by means of suitable apparatus, it was sought by the writer to
+determine, while at this elevation of fifteen thousand feet, _how_
+great the fall of temperature would be if the thin air there could be
+removed altogether; and the result was that the thermometer would under
+such circumstances fall, at any rate, below zero in the full sunshine.
+
+[Illustration: FIG. 71.--PTOLEMY AND ARZACHEL.]
+
+Of course, all this applies indirectly to the moon, above whose
+surface (if these inferences be correct) the mercury in the bulb of a
+thermometer would probably freeze and never melt again during the lunar
+day (and still less during the lunar night),--a conclusion which has
+been reached through other means by Mr. Ericsson,--and whose surface
+itself cannot be very greatly warmer. Other and direct measures of the
+lunar heat are still in progress while this is being written, but their
+probable result seems to be already indicated: it is that the moon’s
+surface, even in perpetual sunshine, must be forever cold. Just how
+cold, is still doubtful; and it is not yet certain whether ice, if once
+formed there, could ever melt.
+
+Here (Fig. 72) is one more scene from the almost unlimited field the
+lunar surface affords.
+
+The most prominent things in the landscape before us are two fine
+craters (Mercator and Campanus), each over thirty miles in diameter;
+but we have chosen this scene for remark rather on account of the great
+crack or rift which is seen in the upper part, and which cuts through
+plain and mountain for a length of sixty miles. Such cracks are counted
+by hundreds on the moon, where they are to be seen almost everywhere;
+and other varieties, in fact, are visible on this same plate, but
+we will not stop to describe them. This one varies in width from an
+eighth of a mile to a mile; and though we cannot see to the bottom
+of it, others are known to be at least eight miles deep, and may be
+indefinitely deeper.
+
+The edge of a cliff on the earth commonly gets weather-worn and
+rounded; but here the edge is sharp, so that a traveller along the
+lunar plains would come to the very brink of this tremendous chasm
+before he had any warning of its existence. It is usually thus with all
+such rifts; and the straightness and sharpness of the edge in these
+cases suggest the appearance of an ice-crack to the observer. I do
+not mean to assert that there is more than a superficial resemblance.
+I do not write as a geologist; but in view of what we have just been
+reading of the lunar cold, we may ask ourselves whether, if water
+ever did exist here, we should not expect to find perpetual ice, not
+necessarily glittering, but covered, perhaps, with the deposits of an
+air laden with the dust-products of later volcanic eruptions, or even
+covered in after ages, when the air has ceased from the moon, with the
+slow deposit of meteoric dust during millions of years of windless
+calm. What else can we think will become of the water on our own earth
+if it be destined to pass through such an experience as we seem to see
+prophesied in the condition of our dead satellite?
+
+The reader must not understand me as saying that there is ice on the
+moon,--only that there is not improbably perpetual ice there now _if_
+there ever was water in past time; and he is not to suppose that to
+say this is in any way to deny what seems the strong evidence of the
+existence of volcanic action everywhere, for the two things may well
+have existed in successive ages of our satellite’s past, or even have
+both existed together, like Hecla, within our own arctic snows; and
+if no sign of any still active lunar volcano has been discovered, we
+appear to read the traces of their presence in the past none the less
+clearly.
+
+I remember that at one time, when living on the lonely upper
+lava-wastes of Mount Etna, which are pitted with little craters, I grew
+acquainted with so many a chasm and rent filled with these, that the
+dreary landscape appeared from above as if a bit of the surface of
+the moon I looked up at through the telescope had been brought down
+beside me.
+
+[Illustration: FIG. 72.--MERCATOR AND CAMPANUS.]
+
+I remember, too, that as I studied the sun there, and watched the
+volcanic outbursts on its surface, I felt that I possibly embraced in a
+threefold picture as many stages in the history of planetary existence,
+through all of which this eruptive action was an agent,--above in the
+primal energies of the sun; all around me in the great volcano, black
+and torn with the fires that still burn below, and whose smoke rose
+over me in the plume that floated high up from the central cone; and
+finally in this last stage in the moon, which hung there pale in the
+daylight sky, and across whose face the vapors of the great terrestrial
+volcano drifted, but on whose own surface the last fire was extinct.
+
+We shall not get an adequate idea of it all, unless we add to our
+bird’s-eye views one showing a chain of lunar mountains as they would
+appear to us if we saw them, as we do our own Alps or Apennines, from
+about their feet; and such a view Fig. 74 affords us. In the barren
+plain on the foreground are great rifts such as we have been looking
+at from above, and smaller craters, with their extinct cones; while
+beyond rise the mountains, ghastly white in the cold sunshine, their
+precipices crowned by no mountain fir or cedar, and softened by no
+intervening air to veil their nakedness.
+
+If the reader has ever climbed one of the highest Alpine peaks, like
+those about Monte Rosa or the Matterhorn, and there waited for the
+dawn, he cannot but remember the sense of desolation and strangeness
+due to the utter absence of everything belonging to man or his works
+or his customary abode, above all which he is lifted into an upper
+world, so novel and, as it were, so unhuman in its features, that he
+is not likely to have forgotten his first impression of it; and this
+impression gives the nearest but still a feeble idea of what we see
+with the telescope in looking down on such a colorless scene, where
+too no water bubbles, no tree can sigh in the breeze, no bird can
+sing,--the home of silence.
+
+[Illustration: FIG. 73.--WITHERED HAND.]
+
+But here, above it, hangs a world in the sky, which we should need to
+call in color to depict, for it is green and yellow with the forests
+and the harvest-fields that overspread its continents, with emerald
+islands studding its gray oceans, over all of which sweep the clouds
+that bring the life-giving rain. It is our own world, which lights up
+the dreary lunar night, as the moon does ours.
+
+[Illustration: FIG. 74.--IDEAL LUNAR LANDSCAPE AND EARTH-SHINE.]
+
+The signs of age are on the moon. It seems pitted, torn, and rent by
+the past action of long-dead fires, till its surface is like a piece
+of porous cinder under the magnifying-glass,--a burnt-out cinder of a
+planet, which rolls through the void like a ruin of what has been; and,
+more significant still, this surface is wrinkled everywhere, till the
+analogy with an old and shrivelled face or hand or fruit (Figs. 73 and
+75), where the puckered skin is folded about a shrunken centre, forces
+itself on our attention, and suggests a common cause,--a something
+underlying the analogy, and making it more than a mere resemblance.
+
+[Illustration: FIG. 75.--WITHERED APPLE.]
+
+The moon, then, is dead; and if it ever was the home of a race like
+ours, that race is dead too. I have said that our New Astronomy
+modifies our view of the moral universe as well as of the physical one;
+nor do we need a more pregnant instance than in this before us. In
+these days of decay of old creeds of the eternal, it has been sought
+to satisfy man’s yearning toward it by founding a new religion whose
+god is Humanity, and whose hope lies in the future existence of our own
+race, in whose collective being the individual who must die may fancy
+his aims and purpose perpetuated in an endless progress. But, alas for
+hopes looking to this alone! we are here brought to face the solemn
+thought that, like the individual, though at a little further date,
+Humanity itself may die!
+
+Before we leave this dead world, let us take a last glance at one of
+its fairest scenes,--that which we obtain when looking at a portion
+on which the sun is rising, as in this view of Gassendi (Fig. 76),
+in which the dark part on our right is still the body of the moon,
+on which the sun has not yet risen. Its nearly level rays stretch
+elsewhere over a surface that is, in places, of a strangely smooth
+texture, contrasting with the ruggedness of the ordinary soil, which is
+here gathered into low plaits, that, with the texture we have spoken
+of, look
+
+    “Like marrowy crapes of China silk,
+    Or wrinkled skin on scalded milk,”
+
+as they lie, soft and almost beautiful, in the growing light.
+
+Where its first beams are kindling, the summits cast their shadows
+illimitedly over the darkening plains away on the right, until they
+melt away into the night,--a night which is not utterly black, for even
+here a subdued radiance comes from the earth-shine of our own world in
+the sky.
+
+Let us leave here the desolation about us, happy that we can come back
+at will to that world, our own familiar dwelling, where the meadows
+are still green and the birds still sing, and where, better yet, still
+dwells our own kind,--surely the world, of all we have found in our
+wanderings, which we should ourselves have chosen to be our home.
+
+[Illustration: FIG. 76.--GASSENDI. NOV. 7, 1867.]
+
+
+
+
+VI.
+
+METEORS.
+
+
+What is truth? What is fact, and what is fancy, even with regard to
+solid visible things that we may see and handle?
+
+Among the many superstitions of the early world and credulous fancies
+of the Middle Ages, was the belief that great stones sometimes fell
+down out of heaven onto the earth.
+
+Pliny has a story of such a black stone, big enough to load a chariot;
+the Mussulman still adores one at Mecca; and a mediæval emperor of
+Germany had a sword which was said to have been forced from one of
+these bolts shot out of the blue. But with the revival of learning,
+people came to know better! That stones should fall down from the sky
+was clearly, they thought, an absurdity; indeed, according to the
+learned opinion of that time, one would hardly ask a better instance
+of the difference between the realities which science recognized and
+the absurdities which it condemned than the fancy that such a thing
+could be. So at least the matter looked to the philosophers of the
+last century, who treated it much as they might treat certain alleged
+mental phenomena, for instance, if they were alive to-day, and at first
+refused to take any notice of these stories, when from time to time
+they still came to hand. When induced to give the matter consideration,
+they observed that all the conditions for scientific observation were
+violated by these bodies, since the wonder always happened at some
+far-off place or at some past time, and (suspicious circumstance!)
+the stones only fell in the presence of ignorant and unscientific
+witnesses, and never when scientific men were at hand to examine the
+facts. That there were many worthy, if ignorant, men who asserted that
+they had seen such stones fall, seen them with their very eyes, and
+held them in their own hands, was accounted for by the general love of
+the marvellous and by the ignorance of the common mind, unlearned in
+the conditions of scientific observation, and unguided by the great
+principle of the uniformity of the Laws of Nature.
+
+Such a tone, of course, cannot be heard among us, who never hastily
+pronounce anything a departure from the “Laws of Nature,” while
+uncertain that these can be separated from the laws of the fallible
+human mind, in which alone Nature is seen. But in the last century
+philosophers had not yet become humble, or scientific men diffident
+of the absoluteness of their own knowledge, and so it seemed that no
+amount of evidence was enough to gain an impartial hearing in the face
+of the settled belief that the atmosphere extended only a few miles
+above the earth’s surface, and that the region beyond, whence alone
+such things could come, was an absolute void extending to the nearest
+planet.
+
+[Illustration: FIG. 77.--THE CAMP AT MOUNT WHITNEY.
+
+(FROM “PROFESSIONAL PAPERS OF THE SIGNAL SERVICE,” VOL. XV.)]
+
+It used to be supposed that we were absolutely isolated, not only from
+the stars but from other planets, by vast empty spaces extending from
+world to world,--regions altogether vacant except for some vagrant
+comet; but of late years we are growing to have new ideas on this
+subject, and not only to consider space as far from void or tenantless,
+but to admit, as a possibility at least, that there is a sort of
+continuity between our very earth’s surface, the air above it, and
+all which lies beyond the blue overarching dome of our own sky. Our
+knowledge of the physical nature of the universe without has chiefly
+come from what the spectroscope, overleaping the space between us
+and the stars, has taught us of them; as a telegram might report to
+us the existence of a race across the ocean, without telling anything
+of what lay between. It would be a novel path to the stars, and to the
+intermediate regions whence these once mythical stones are now actually
+believed to come, if we could take the reader to them by a route which
+enabled us to note each step of a continuous journey from the earth’s
+surface out into the unknown; but if we undertake to start upon it, he
+will understand that we must almost at the outset leave the ground of
+comparative certainty on which we have hitherto rested, and need to
+speak of things on this road which are still but probabilities, and
+even some which are little more than conjectures, before we get to the
+region of comparative certainty again,--a region which, strange to say,
+exists far away from us, while that of doubt lies close at hand, for we
+may be said without exaggeration to know more about Sirius than about
+the atmosphere a thousand miles above the earth’s surface; indeed, it
+would be more just to say that we are sure not only of the existence
+but of the elements that compose a star, though a million of times as
+far off as the sun, while at the near point named we are not sure of so
+much as that the atmosphere exists at all.
+
+To begin our outward journey in a literal sense, we might rise from
+the earth’s surface some miles in a balloon, when we should find our
+progress stayed by the rarity of the air. Below us would be a gray
+cloud-ocean, through which we could see here and there the green
+earth beneath, while above us there would still be something in the
+apparently empty air, for if the sun has just set it will still be
+_light_ all round us. Something then, in a cloudless sky, still exists
+to reflect the rays towards us, and this something is made up of
+separately invisible specks of dust and vapor, but very largely of
+actual dust, which probably forms the nucleus of each mist-particle.
+That discrete matter of some kind exists here has long been recognized
+from the phenomena of twilight; but it is, I think, only recently that
+we are coming to admit that a shell of actual solid particles in the
+form of dust probably encloses the whole globe, up to far above the
+highest clouds.
+
+In 1881 the writer had occasion to conduct a scientific expedition to
+the highest point in the territories of the United States, on one of
+the summits of the Sierra Nevadas of Southern California, which rise
+even above the Rocky Mountains.
+
+The illustration on page 177 represents the camp occupied by this party
+below the summit, where the tents, which look as if in the bottom of a
+valley, are yet really above the highest zone of vegetation, and at an
+altitude of nearly twelve thousand feet.
+
+Still above these rise the precipices of barren rock seen in
+the background, their very bases far above the highest visible
+dust-clouds, which overspread like a sea the deserts at the mountain’s
+foot,--precipices which when scaled lift the observer into what is,
+perhaps, the clearest and purest air to be found in the world. It will
+be seen from the mere looks of the landscape that we are far away here
+from ordinary sources of contamination in the atmosphere. Yet even
+above here on the highest peak, where we felt as if standing on the
+roof of the continent and elevated into the great aerial currents of
+the globe, the telescope showed particles of dust in the air, which the
+geologists deemed to have probably formed part of the soil of China
+and to have been borne across the Pacific, but which also, as we shall
+see later, may owe something to the mysterious source of the phenomena
+already alluded to.
+
+It is far from being indifferent to us that the dust is there; for, to
+mention nothing else, without it, it would be night till the sunrise,
+and black night again as soon as the sun’s edge disappeared below
+the horizon. The morning and the evening twilight, which in northern
+latitudes increase our average time of light by some hours, and add
+very materially to the actual days of man’s life, are probably due
+almost wholly to particles scarcely visible in the microscope, and to
+the presence of such atoms, smaller than the very motes ordinarily
+seen in the sunbeam, which, as Mr. Aitken has shown, fill the air we
+breathe,--so minute and remote are the causes on which the habits of
+life depend.
+
+Before we can see that a part of this impalpable, invisible dust is
+also perhaps a link between our world and other members of the solar
+system, we must ask how it gets into the atmosphere. Is it blown up
+from the earth, or does it fall down out of the miscalled “void” of
+space?
+
+If we cast a handful of dust into the air, it will not mount far above
+the hand unless we set the air in motion with it, as in ascending
+smoke-currents; and the greatest explosions we can artificially
+produce, hurl their finer products but a few hundred feet at most from
+the soil. Utterly different are the forces of Nature. We have on page
+183 a reproduction from a photograph of an eruption of Vesuvius,--a
+mere toy-volcano compared to Etna or Hecla. But observe the smoke-cloud
+which rises high in the sunshine, looking solid as the rounded snows of
+an Alp, while the cities and the sea below are in the shadow. The smoke
+that mounts from the foreground, where the burning lava-streams are
+pouring over the surface and firing the woods, is of another kind from
+that rolling high above. _This_ comes from within the mountain, and
+is composed of clouds of steam mingled with myriads of dust-particles
+from the comminuted products of the earth’s interior; and we can see
+ourselves that it is borne away on a level, miles high in the upper air.
+
+But what is this to the eruption of Sumbawa or Krakatao? The latter
+occurred in 1883, and it will be remembered that the air-wave started
+by the explosion was felt around the globe, and that, probably owing
+to the dust and water-vapor blown into the atmosphere, the sunsets
+even in America became of that extraordinary crimson we all remember
+three years ago; and coincidently, that dim reddish halo made its
+appearance about the sun, the world over, which is hardly yet gone.[6]
+Very careful estimates of the amount of ashes ejected have been made;
+and though most of the heavier particles are known to have fallen
+into the sea within a few miles, a certain portion--the lightest--was
+probably carried by the explosion far above the lower strata of the
+atmosphere, to descend so slowly that some of it may still be there.
+Of this lighter class the most careful estimates must be vague; but
+according to the report of the official investigation by the Dutch
+Government, that which remained floating is something enormous. An idea
+of its amount may be gained by supposing these impalpable and invisible
+particles to condense again from the upper sky, and to pour down on
+the highest edifice in the world, the Washington Monument. If the dust
+were allowed to spread out on all sides, till the pyramidal slope was
+so flat as to be permanent, the capstone of the monument would not only
+be buried before the supply was exhausted, but buried as far below the
+surface as that pinnacle is now above it.
+
+    [6] In January, 1887.
+
+Of the explosive suddenness with which the mass was hurled, we can
+judge something (comparing small things with great) by the explosion of
+dynamite.
+
+It happened once that the writer was standing by a car in which some
+railway porters were lifting boxes. At that moment came an almost
+indescribable sound, for it was literally stunning, though close and
+sharp as the crack of a whip in one’s hand, and yet louder than the
+nearest thunder-clap. The men leaped from the car, thinking that one of
+the boxes had exploded between them; but the boxes were intact, and we
+saw what seemed a pillar of dust rising above the roof of the station,
+hundreds of yards away. When we hurried through the building, we
+found nothing on the other side but a bare plain, extending over a
+mile, and beyond this the actual scene of the explosion that had
+seemed to be at our feet. There had been there, a few minutes before,
+extensive buildings and shops belonging to the railroad, and sidings
+on which cars were standing, two of which, loaded with dynamite, had
+exploded.
+
+[Illustration: FIG. 78.--VESUVIUS DURING AN ERUPTION.]
+
+Where they _had_ been was a crater-like depression in the earth, some
+rods in diameter; the nearest buildings, great solid structures of
+brick and stone, had vanished, and the more distant wooden ones and the
+remoter lines of freight-cars on the side-tracks presented a curious
+sight, for they were not shattered so much as bent and leaning every
+way, as though they had been built of pasteboard, like card-houses,
+and had half yielded to some gigantic puff of breath. All that the
+explosion had shot skyward had settled to earth or blown away before
+we got in sight of the scene, which was just as quiet as it had been a
+minute before. It was like one of the changes of a dream.
+
+Now, it is of some concern to us to know that the earth holds within
+itself similar forces, on an incomparably greater scale. For instance,
+the explosion which occurred at Krakatao, at five minutes past ten, on
+the 27th of August, 1883, according to official evidence, was heard
+at a distance of eighteen hundred miles, and the puff of its air-wave
+injured dwellings two hundred miles distant, and, we repeat, carried
+into the highest regions of the atmosphere and around the world matter
+which it is at least possible still affects the aspect of the sun
+to-day from New York or Chicago.
+
+Do not the great flames which we have seen shot out from the sun
+at the rate of hundreds of miles a second, the immense and sudden
+perturbations in the atmosphere of Jupiter, and the scarred surface of
+the moon, seem to be evidences of analogous phenomena, common to the
+whole solar system, not wholly unconnected with those of earthquakes,
+and which we can still study in the active volcanoes of the earth?
+
+If the explosion of gunpowder can hurl a cannon-shot three or four
+miles into the air, how far might the explosion of Krakatao cast its
+fragments? At first we might think there must be some proportionality
+between the volume of the explosion and the distance, but this is not
+necessarily so. Apart from the resistance of the air, it is a question
+of the velocity with which the thing is shot upward, rather than the
+size of the gun, or the size of the thing itself, and with a sufficient
+velocity the projectile would never fall back again. “What goes up
+must come down,” is, like most popular maxims, true only within the
+limits of ordinary experience; and even were there nothing else in the
+universe to attract it, and though the earth’s attraction extend to
+infinity, so that the body would never escape from it, it is yet quite
+certain that it would, with a certain initial velocity (very moderate
+in comparison with that of the planet itself), go up and _never_ come
+back; while under other and possible conditions it might voyage out
+into space on a comet-like orbit, and be brought back to the earth,
+perhaps in after ages, when the original explosion had passed out of
+memory or tradition. But because all this is possible, it does not
+follow that it is necessarily true; and if the reader ask why he should
+then be invited to consider such suppositions at all, we repeat that
+in our journey outward, before we come to the stars, of which we know
+something, we pass through a region of which we know almost nothing;
+and this region, which is peopled by the subjects of conjecture, is
+the scene, if not the source, of the marvel of the falling stones,
+concerning which the last century was so incredulous, but for which
+we can, aided by what has just been said, now see at least a possible
+cause, and to which we now return.
+
+Stories of falling stones, then, kept arising from time to time during
+the last century as they had always done, and philosophers kept on
+disbelieving them as they had always done, till an event occurred which
+suddenly changed scientific opinion to compulsory belief.
+
+On the 26th of April, 1803, there fell, not in some far-off part of the
+world, but in France, not one alone, but many thousand stones, over
+an area of some miles, accompanied with noises like the discharge of
+artillery. A committee of scientific men visited the spot on the part
+of the French Institute, and brought back not only the testimony of
+scores of witnesses or auditors, but the stones themselves. Soon after
+stones fell in Connecticut, and here and elsewhere, as soon as men were
+prepared to believe, they found evidence multiplied; and such falls,
+it is now admitted, though rare in any single district, are of what
+may be called frequent occurrence as regards the world at large,--for,
+taking land and sea together, the annual stone-falls are probably to be
+counted by hundreds.
+
+It was early noticed that these stones consisted either of a peculiar
+alloy of iron, or of minerals of volcanic origin, or both; and the
+first hypothesis was that they had just been shot out from terrestrial
+volcanoes. As they were however found, as in the case of the
+Connecticut meteorite, thousands of miles from any active volcanoes,
+and were seen to fall, not vertically down, but as if shot horizontally
+overhead, this view was abandoned. Next the idea was suggested that
+they were coming from volcanoes in the moon; and though this had
+little to recommend it, it was adopted in default of a better, and
+entertained down to a comparatively very recent period. These stones
+are now collected in museums, where any one may see them, and are to be
+had of the dealers in such articles by any who wish to buy them. They
+are coming to have such a considerable money value that, in one case
+at least, a lawsuit has been instituted for their possession between
+the finder, who had picked the stones up on ground leased to him, and
+claimed them under the tenant’s right to wild game, and his landlord,
+who thought they were his as part of the real estate.
+
+Leaving the decision of this novel law-point to the lawyers, let us
+notice some facts now well established.
+
+The fall is usually preceded by a thundering sound, sometimes followed
+or accompanied by a peculiar noise described as like that of a flock
+of ducks rising from the water. The principal sound is often, however,
+far louder than any thunder, and sometimes of stunning violence. At
+night this is accompanied by a blaze of lightning-like suddenness and
+whiteness, and the stones commonly do not fall vertically, but as if
+shot from a cannon at long range. They are usually burning hot, but
+in at least one authenticated instance one was so intensely cold that
+it could not be handled. They are of all sizes, from tons to ounces,
+comparatively few, however, exceeding a hundred-weight, and they
+are oftenest of a rounded form, or looking like pieces of what was
+originally round, and usually wholly or partly covered with a glaze
+formed of the fused substance itself. If we slowly heat a lump of loaf
+sugar all through, it will form a pasty mass, while we may also hold it
+without inconvenience in our fingers to the gas-flame a few seconds,
+when it will be melted only on the side next the sudden heat, and
+rounded by the melting. The sharp contrast of the melted and the rough
+side is something like that of the meteorites; and just as the sugar
+does not burn the hand, though close to where it is brought suddenly
+to a melting heat, a mass of ironstone may be suddenly heated on the
+surface, while it remains cold on the inside. But, however it got
+there, the stone undoubtedly comes from the intensely cold spaces above
+the upper air; and what is the source of such a heat that it is melted
+in the cold air, and in a few seconds?
+
+[Illustration: FIG. 79.--METEORS OBSERVED NOV. 13 AND 14, 1868, BETWEEN
+MIDNIGHT AND FIVE O’CLOCK, A. M.]
+
+Everybody has noticed that if we move a fan gently, the air parts
+before it with little effort, while, when we try to fan violently,
+the same air is felt to react; yet if we go on to say that if the
+motion is still more violent the atmosphere will resist like a solid,
+against which the fan, if made of iron, would break in pieces, this may
+seem to some an unexpected property of the “nimble” air through which
+we move daily. Yet this is the case; and if the motion is only so quick
+that the air cannot get out of the way, a body hurled against it will
+rise in temperature like a shot striking an armor-plate. It is all a
+question of speed, and that of the meteorite is known to be immense.
+One has been seen to fly over this country from the Mississippi to
+the Atlantic in an inappreciably short time, probably in less than
+two minutes; and though at a presumable height of over fifty miles,
+the velocity with which it shot by gave every one the impression that
+it went just above his head, and some witnesses of the unexpected
+apparition looked the next day to see if it had struck their chimneys.
+The heat developed by arrested motion in the case of a mass of iron
+moving twenty miles a second can be calculated, and is found to be
+much more than enough, not only to melt it, but to turn it into vapor;
+though what probably does happen is, according to Professor Newton,
+that the melted surface-portions are wiped away by the pressure of the
+air and volatilized to form the luminous train, the interior remaining
+cold, until the difference of temperature causes a fracture, when the
+stone breaks and pieces fall,--some of them at red-hot heat, some of
+them possibly at the temperature of outer space, or far below that of
+freezing mercury.
+
+Where do these stones come from? What made them? The answer is not yet
+complete; but if a part of the riddle is already yielding to patience,
+it is worthy of note, as an instance of the connection of the sciences,
+that the first help to the solution of this astronomical enigma came
+from the chemists and the geologists.
+
+The earliest step in the study, which has now been going on for many
+years, was to analyze the meteorite, and the first result was that it
+contained no elements not found on this planet. The next was that,
+though none of these elements were unknown, they were not combined
+as we see them in the minerals we dig from the earth. Next it was
+found that the combinations, if unfamiliar at the earth’s surface and
+nowhere reproduced exactly, were at least very like such as existed
+down beneath it, in lower strata, as far as we can judge by specimens
+of the earth’s interior cast up from volcanoes. Later, a resemblance
+was recognized in the elements of the meteorites to those found by the
+spectroscope in shooting stars, though the spectroscopic observation
+of the latter is too difficult to have even yet proceeded very far.
+And now, within the last few years, we seem to be coming near to a
+surprising solution.
+
+It has now been shown that meteoric stones sometimes contain pieces
+of essentially different rocks fused together, and pieces of
+detritus,--the wearing down of older rocks. Thus, as we know that
+sandstone is made of compacted sand, and sand itself was in some
+still earlier time part of rocks worn down by friction,--when it is
+shown, as it has been by M. Meunier, that a sandstone penetrated by
+metallic threads (like some of our terrestrial formations) has come
+to us in a meteorite, the conclusion that these stones may be part
+of some old world is one that, however startling, we cannot refuse
+at least to consider. According to this view, there may have been a
+considerable planet near the earth, which, having reached the last
+stage of planetary existence shown in the case of our present moon,
+went one step further,--went, that is, out of existence altogether, by
+literal breaking up and final disappearance. We have seen the actual
+moon scarred and torn in every direction, and are asked to admit the
+possibility that a continuance of the process on a similar body has
+broken it up into the fragments that come to us. We do not say that
+this is the case, but that (as regards the origin of some of the
+meteorites at least) we cannot at present disprove it. We may, at any
+rate, present to the novelist seeking a new _motif_ that of a meteorite
+bringing to us the story of a lost race, in some fragment of art or
+architecture of its lost world!
+
+We are not driven to this world-shattering hypothesis by the absence
+of others, for we may admit these to be fragments of a larger body
+without necessarily concluding that it was a world like ours, or, even
+if it were, that the world which sent them to us is destroyed. In view
+of what we have been learning of the tremendous explosive forces we
+see in action on the sun and probably on other planets, and even in
+terrestrial volcanoes to-day, it is certainly conceivable that some
+of these stones may have been ejected by some such process from any
+sun, or star, or world we see. The reader is already prepared for
+the suggestion that part of them may be the product of terrestrial
+volcanoes in early epochs, when our planet was yet glowing sunlike with
+its proper heat, and the forces of Nature were more active; and that
+these errant children of mother earth’s youth, after circulating in
+lengthened orbits, are coming back to her in her age.
+
+Do not let us, however, forget that these are mostly speculations only,
+and perhaps the part of wisdom is not to speculate at all till we learn
+more facts; but are not the facts themselves as extraordinary as any
+invention of fancy?
+
+Although it is true that the existence of the connection between
+shooting stars and meteorites lacks some links in the chain of proof,
+we may very safely consider them together; and if we wish to know what
+the New Astronomy has done for us in this field, we should take up
+some treatise on astronomy of the last century. We turn in one to the
+subject of falling stars, and find that “this species of Star is only
+a light Exhalation, almost wholly sulphurous, which is inflamed in
+the free Air much after the same manner as Thunder in a Cloud by the
+blowing of the Winds.” That the present opinion is different, we shall
+shortly notice.
+
+All of us have seen shooting stars, and they are indeed something
+probably as old as this world, and have left their record in mythology
+as well as in history. According to Moslem tradition, the evil genii
+are accustomed to fly at night up to the confines of heaven in order to
+overhear the conversation of the angels, and the shooting stars are the
+fiery arrows hurled by the latter at their lurking foes, with so good
+an aim that we are told that for every falling star we may be sure that
+there is one spirit of evil the less in the world. The scientific view
+of them, however, if not so consolatory, is perhaps more instructive,
+and we shall here give most attention to the latter.
+
+To begin with, there have been observed in history certain times when
+shooting stars were unusually numerous. The night when King Ibrahim Ben
+Ahmed died, in October, 902, was noted by the Arabians as remarkable in
+this way; and it has frequently been observed since, that, though we
+can always see some of these meteors nightly, there are at intervals
+very special displays of them. The most notable modern one was on
+Nov. 13, 1833, and this was visible over much of the North American
+continent, forming a spectacle of terrifying grandeur. An eyewitness in
+South Carolina wrote:--
+
+  “I was suddenly awakened by the most distressing cries that ever
+  fell on my ears. Shrieks of horror and cries for mercy I could
+  hear from most of the negroes of the three plantations, amounting
+  in all to about six hundred or eight hundred. While earnestly
+  listening for the cause I heard a faint voice near the door,
+  calling my name. I arose, and, taking my sword, stood at the
+  door. At this moment I heard the same voice still beseeching me
+  to rise, and saying, ‘O my God, the world is on fire!’ I then
+  opened the door, and it is difficult to say which excited me
+  the most--the awfulness of the scene, or the distressed cries
+  of the negroes. Upwards of one hundred lay prostrate on the
+  ground,--some speechless and some with the bitterest cries, but
+  with their hands raised, imploring God to save the world and
+  them. ‘The scene was truly awful; for never did rain fall much
+  thicker than the meteors fell toward the earth; east, west,
+  north, and south, it was the same.”
+
+The illustration on page 189 does not exaggerate the number of the
+fiery flashes at such a time, though the zigzag course which is
+observed in some is hardly so common as it here appears.
+
+When it was noted that the same date, November 13th, had been
+distinguished by star-showers in 1831 and 1832, and that the great
+shower observed by Humboldt in 1799 was on this day, the phenomenon was
+traced back and found to present itself about every thirty-three years,
+the tendency being to a little delay on each return; so that Professor
+Newton and others have found it possible with this clew to discover
+in early Arabic and other mediæval chronicles, and in later writers,
+descriptions which, fitted together, make a tolerably continuous record
+of this thirty-three-year shower, beginning with that of King Ibrahim
+already alluded to. The shower appeared again in November, 1867 and
+1868, with less display, but with sufficient brilliance to make the
+writer well remember the watch through the night, and the count of the
+flying stars, his most lively recollection being of their occasional
+colors, which in exceptional cases ranged from full crimson to a vivid
+green. The count on this night was very great, but the number which
+enter the earth’s atmosphere even ordinarily is most surprising; for,
+though any single observer may note only a few in his own horizon,
+yet, taking the world over, at least ten millions appear every night,
+and on these special occasions very many more. This November shower
+comes always from a particular quarter of the sky, that occupied by the
+constellation Leo, but there are others, such as that of August 10th
+(which is annual), in which the “stars” seem to be shot at us from the
+constellation Perseus; and each of the numerous groups of star-showers
+is now known by the name of the constellation whence it seems to come,
+so that we have _Perseids_ on August 10th, _Geminids_ on December 12th,
+_Lyrids_, April 20th, and so on.
+
+The great November shower, which is coming once more in this century,
+and which every reader may hope to see toward 1899, is of particular
+interest to us as the first whose movements were subjected to analysis;
+for it has been shown by the labors of Professor Newton, of Yale, and
+Adams, of Cambridge, that these shooting stars are bodies moving around
+the sun in an orbit which is completed in about thirty-three years. It
+is quite certain, too, that they are not exhalations from the earth’s
+atmosphere, but little solids, invisible till they shine out by the
+light produced by their own fusion. Each, then, moves on its own track,
+but the general direction of all the tracks concurs; and though some
+of them may conceivably be solidified gases, we should think of them
+not as gaseous in form, but as solid shot, of the average size of
+something like a cherry, or perhaps even of a cherry-stone, yet each
+an independent planetoid, flying with a hundred times the speed of a
+rifle-bullet on its separate way as far out as the orbit of Uranus;
+coming back three times in a century to about the earth’s distance from
+the sun, and repeating this march forever, unless it happen to strike
+the atmosphere of the earth itself, when there comes a sudden flash of
+fire from the contact, and the distinct existence of the little body,
+which may have lasted for hundreds of thousands of years, is ended in a
+second.
+
+If the reader will admit so rough a simile, we may compare such a
+flight of these bodies to a thin swarm of swift-flying birds--thin, but
+yet immensely long, so as to be, in spite of the rapid motion, several
+years in passing a given point, and whose line of flight is cut across
+by us on the 13th of November, when the earth passes through it. We
+are only there on that day, and can only see it then; but the swarm is
+years in all getting by, and so we may pass into successive portions
+of it on the anniversary of the same day for years to come. The stars
+appear to shoot from Leo, only because that constellation is in the
+line of their flight when we look up to it, just as an interminable
+train of parallel flying birds would appear to come from some definite
+point on the horizon.
+
+We can often see the flashes of meteors at over a hundred miles, and
+though at times they may seem to come thick as Hakes of falling snow,
+it is probable, according to Professor Newton, that even in a “shower”
+each tiny planetoid is more than ten miles from its nearest neighbor,
+while on the average it is reckoned that we may consider that each
+little body, though possibly no larger than a pea, is over two hundred
+miles from its neighbor, or that to each such grain there is nearly
+ten million cubic miles of void space. Their velocity as compounded
+with that of the earth is enormous, sometimes forty to fifty miles per
+second (according to a recent but unproved theory of Mr. Denning, it
+would be much greater), and it is this enormous rate of progress that
+affords the semblance of an abundant fall of rain, notwithstanding the
+distance at which one drop follows another. It is only from their light
+that we are able to form a rough estimate of their average size, which
+is, as we have seen, extremely small; but, from their great number,
+the total weight they add to the earth daily may possibly be a hundred
+tons, probably not very much more. As they are as a rule entirely
+dissipated in the upper air, often at a height of from fifty to seventy
+miles, it follows that many tons of the finest pulverized and gaseous
+matter are shot into the earth’s atmosphere every twenty-four hours
+from outer space, so that here is an independent and constant supply
+of dust, which we may expect to find coming down from far above the
+highest clouds.
+
+Now, when the reader sees the flash of a shooting star, he may, if he
+please, think of the way the imagination of the East accounts for it,
+or he may look at what science has given him instead. In the latter
+case he will know that a light which flashed and faded almost together
+came from some strange little entity which had been traversing cold
+and vacant space for untold years, to perish in a moment of more than
+fiery heat; an enigma whose whole secret is unknown, but of which,
+during that instant flash, the spectroscope caught a part, and found
+evidence of the identity of some of its constituents with those of the
+observer’s own body.
+
+
+
+
+VII.
+
+COMETS.
+
+
+Of comets, the Old Astronomy knew that they came to the sun from great
+distances in all directions, and in calculable orbits; but as to
+_what_ they were, this, even in the childhood of those of us who are
+middle-aged, was as little known as to the centuries during which they
+still from their horrid heads shook pestilence and war. We do not know
+even now by any means exactly what they are, for enough yet remains to
+be learned about them still to give their whole study the attraction
+which belongs to the unknown; and yet we learn so much, and in a way
+which to our grandfathers would have been so unexpected, connecting
+together the comet, the shooting star, and the meteorite, that the
+astronomer who perhaps speaks with most authority about these to-day
+was able, not long ago, in beginning a lecture, to state that he held
+in his hand what had been a part of a comet; and what he held was,
+not something half vaporous or gaseous, as we might suppose from our
+old associations, but a curious stone like this on page 203, which,
+with others, had fallen from the sky in Iowa, a flashing prodigy, to
+the terror of barking dogs, shying horses, and fearful men, followed
+by clouds of smoke and vapor, and explosions that shook the houses
+like an earthquake, and “hollow bellowings and rattling sounds mingled
+with clang and clash and roar,” as an auditor described it. It is only
+a fragment of a larger stone which may have weighed tons. It looks
+inoffensive enough now, and its appearance affords no hint of the
+commotion it caused in a peaceable neighborhood only ten years ago. But
+what, it may be asked, is the connection between such things and comets?
+
+To answer this, let us recall the statement that the orbit of the
+November meteor swarm has been computed; which means that those flying
+bodies have been found to come only from one particular quarter out
+of all possible quarters, at one particular angle out of all possible
+angles, at one particular velocity out of all possible velocities, and
+so on; so that the chances are endless against mere accident producing
+another body which agreed in all these particulars, and others besides.
+Now, in 1867 the remarkable fact was established that a comet seen in
+the previous year (Comet 1, 1866) had the same orbit as the meteoroids,
+which implies, as we have just seen, that the comet and the meteors
+were in some way closely related.
+
+The paths of the August meteors and of the Lyrids also have both been
+found to agree closely with those of known comets, and there is other
+evidence which not only connects the comets and the shooting stars, and
+makes it probable that the latter are due to some disintegration of the
+former, but even looks as though the process were still going on. And
+now with this in mind we may, perhaps, look at these drawings with more
+interest.
+
+[Illustration: FIG. 80.--COMET OF DONATI, SEPT. 16, 1858.[7]]
+
+    [7] The five engravings of the Comet of Donati are from “Annals
+        of the Astronomical Observatory of Harvard College.”
+
+We have all seen a comet, and we have all felt, perhaps, something of
+the awe which is called up by the thought of its immensity and its rush
+through space like a runaway star. Its head is commonly like a small
+luminous point, from which usually grows as it approaches the sun a
+relatively enormous brush or tail of pale light, which has sometimes
+been seen to stretch across the whole sky from zenith to horizon. It
+is useless to look only along the ecliptic road for a comet’s coming;
+rather may we expect to see it rushing down from above, or up from
+below, sometimes with a speed which is possibly greater than it
+could get from any fall--not so much, that is, the speed of a body
+merely dropping toward the sun by its weight, as that of a missile
+hurled into the orderly solar system from some unknown source without,
+and also associated with some unknown power; for while it is doubtful
+whether gravity is sufficient to account for the velocity of all
+comets, it seems certain that gravity can in no way explain some of the
+phenomena of their tails.
+
+[Illustration: FIG. 81.--“A PART OF A COMET.”]
+
+Thousands of comets have been seen since the Christian era, and the
+orbits of hundreds have been calculated since the time of Newton.
+Though they may describe any conic section, and though most orbits
+are spoken of as parabolas, this is rather a device for the analyst’s
+convenience than the exact representation of fact. Without introducing
+more technical language, it will be enough to say here that we learn
+in other cases from the form of the orbit whether the body is drawn
+essentially by the sun’s gravity, or whether it has been thrown into
+the system by some power beyond the sun’s control, to pass away again,
+out of that control, never to return. It must be admitted, however,
+that though several orbits are so classed, there is not any one known
+to be beyond doubt of this latter kind, while we are certain that many
+comets, if not all, are erratic members of the solar family, coming
+back again after their excursions, at regular, though perhaps enormous,
+intervals.
+
+But what we have just been saying belongs rather to the province of
+the Old Astronomy than the New, which concerns itself more with the
+nature and appearance of the heavenly bodies than the paths they travel
+on. Perhaps the best way for us to look at comets will be to confine
+our attention at first to some single one, and to follow it from its
+earliest appearance to its last, by the aid of pictures, and thus
+to study, as it were, the species in the individual. The difficulty
+will be one which arises from the exquisitely faint and diaphanous
+appearance of the original, which no ordinary care can possibly render,
+though here the reader has had done for him all that the wood-engraver
+can do.
+
+We will take as the subject of our illustration the beautiful comet
+which those of us who are middle-aged can remember seeing in 1858,
+and which is called Donati’s from the name of its discoverer. We
+choose this one because it is the subject of an admirable monograph
+by Professor Bond of the Harvard College Observatory, from which our
+engravings have, by permission, been made.
+
+Let us take the history of this comet, then, as a general type of
+others; and to begin at the beginning, we must make the very essential
+admission that the origin of the comet’s life is unknown to us. Where
+it was born, or how it was launched on its eccentric path, we can only
+guess, but do not know; and how long it has been traversing it we can
+only tell later. On the 2d of June, 1858, this one was discovered
+in the way most comets are found, that is, by a _comet-hunter_, who
+detected it as a telescopic speck long before it became visible to the
+naked eye, or put forth the tail which was destined to grow into the
+beautiful object many of us can remember seeing. For over a century now
+there has been probably no year in which the heavens have not been thus
+searched by a class of observers who make comet-hunting a specialty.
+
+[Illustration: FIG. 82.--COMET OF DONATI, SEPT. 24, 1858. (TELESCOPIC
+VIEW OF HEAD.)]
+
+The father of this very valuable class of observers appears to have
+been Messier, a Frenchman of the last century and of the purest type of
+the comet-hunters, endowed by Nature with the instinct for their search
+that a terrier has for rats. In that grave book, Delambre’s “History of
+Astronomy,” as we plod along its dry statements and through its long
+equations, we find, unexpected as a joke in a table of logarithms, the
+following piece of human nature (quoted from Messier’s contemporary, La
+Harpe):--
+
+  “He [Messier] has passed his life in nosing out the tracks
+  of comets. He is a very worthy man, with the simplicity of a
+  baby. Some years ago he lost his wife, and his attention to her
+  prevented him from discovering a comet he was on the search for,
+  and which Montaigne of Limoges got away from him. He was in
+  despair. When he was condoled with on the loss he had met, he
+  replied, with his head full of the comet, ‘Oh, dear! to think
+  that when I had discovered twelve, this Montaigne should have got
+  my thirteenth.’ And his eyes filled with tears, till, remembering
+  what it was he ought to be weeping for, he moaned, ‘Oh, my poor
+  wife!’ but went on crying for his comet.”
+
+Messier’s scientific posterity has greatly multiplied, and it is rare
+now for a comet to be seen by the naked eye before it has been caught
+by the telescope of one of these assiduous searchers. Donati had, as
+we see, observed his some months before it became generally visible,
+and accordingly the engraving on page 201 shows it as it appeared on
+the evening of September 16, 1858, when the tail was already formed,
+and, though small, was distinct to the naked eye, near the stars of the
+Great Bear. The reader will easily recognize in the plate the familiar
+“dipper,” as the American child calls it, where the leading stars are
+put down with care, so that he may, if he please, identify them by
+comparison with the originals in the sky, even to the little companion
+to Mizar (the second in the handle of the “dipper,” and which the
+Arabs say is the lost Pleiad). We would suggest that he should note
+both the length of the tail on this evening as compared with the space
+between any two stars of the “dipper” (for instance, the two right-hand
+ones, called the “pointers”) and its distance from them, and then turn
+to page 209, where we have the same comet as seen a little over a
+fortnight later, on October 3d. Look first at its new place among the
+stars. The “dipper” is still in view, but the comet has drifted away
+from it toward the left and into other constellations. The large star
+close to the left margin of the plate, with three little stars below
+and to the right, is Arcturus; and the western stars of the Northern
+Crown are just seen higher up. Fortunately the “pointers,” with which
+we compared the comet on September 16th, are still here, and we can see
+for ourselves how it has not only shifted but grown. The tail is three
+times as long as before. It is rimmed with light on its upper edge,
+and fades away so gradually below that one can hardly say where it
+ends. But,--wonderful and incomprehensible feature!--shot out from the
+head, almost as straight as a ray of light itself, but fainter than the
+moonbeam, now appears an extraordinary addition, a sort of spur, which
+we can hardly call a new tail, it is so unlike the old one, but which
+appears to have been darted out into space as if by some mysterious
+force acting through the head itself. What the spur is, what the tail
+is, even what the nucleus is, we cannot be said really to know even
+to-day; but of the tail and of the nucleus or speck in the very head of
+the comet (too small to be visible in the engraving), we may say that
+the hairy tail (_comes_) gives the comet its name, and _is_ the comet
+to popular apprehension, but that it is probably the smallest part of
+the whole mass, while the little shining head, which to the telescope
+presents a still smaller speck called the nucleus, contains, it now
+seems probable, the only element of possible danger to the earth.
+
+While admitting our lack of absolute knowledge, we may, if we agree
+that meteorites were once part of a comet, say that it now seems
+probable that the nucleus is a hard, stone-like mass, or collection
+of such masses, which comes from “space” (that is, from we don’t know
+how far) to the vicinity of the sun, and there is broken by the heat
+as a stone in a hot fire. (Sir Isaac Newton calculates, in an often
+quoted passage of the Principia, that the heat which the comet of 1680
+was subjected to in its passage by the sun was two thousand times
+that of red-hot iron.) We have seen the way in which meteoric stones
+actually do crack in pieces with heat in our own atmosphere, partly,
+perhaps, from the expansion of the gases the stone contains, and it
+seems entirely reasonable to suppose that they may do so from the heat
+of the sun, and that the escaped gases may contribute something toward
+the formation of the tail, which is always turned away from the sun,
+and which always grows larger as that is approached, and smaller as
+it is receded from. However this may be, there is no doubt that the
+original solid which we here suppose may form the nucleus is capable
+of mischief, for it is asserted that it often passes the earth’s orbit
+with a velocity of as much as one hundred times that of a cannon-ball;
+that is, with ten thousand times the destructive capacity of a ball of
+the same weight shot from a cannon.
+
+[Illustration: FIG. 83.--COMET OF DONATI, OCT. 3, 1858.]
+
+One week later, October 9th, the comet had passed over Arcturus
+with a motion toward our left into a new region of the sky, leaving
+Arcturus, which we can recognize with the upper one of its three little
+companions, on the right. Above it is the whole sickle of the Northern
+Crown, and over these stars the extremity of the now lengthened tail
+was seen to spread, but with so thin a veil that no art of the engraver
+can here adequately represent its faintness. The tail then, as seen in
+the sky, was now nearly twice its former size, though for the reason
+mentioned it may not appear so in our picture. It should be understood,
+too, that even the brightest parts of the original were far fainter
+than they seem here in comparison with the stars, which in the sky
+are brilliant points of light, which the engraver can only represent
+by dots of the whiteness of the paper. This being observed, it will
+be better understood that in the sky itself the faintest stars were
+viewed apparently undimmed through the brighter parts of the comet,
+while we can but faintly trace here another most faint but curious
+feature, a division of the tail into faint cross-bands like auroral
+streamers, giving a look as if it were yielding to a wind, which folded
+it into faint ridges like those which may be seen in the smoke of a
+steamer as it lags far behind the vessel. In fact, when we speak of
+“the” tail, it must be understood, as M. Faye reminds us, to be in
+the same sense that we speak of the plume of smoke that accompanies
+an ocean steamer, without meaning that it is the same thing which
+we are watching from night to night, more than we do that the same
+smoke-particles accompany the steamer as it moves across the Atlantic.
+In both cases the form alone probably remains; the thing itself is
+being incessantly dissipated and renewed. There is no air here, and yet
+some of these appearances in the original almost suggest the idea of
+medium inappreciably thin as compared with the head of the comet, but
+whose resistance is seen in the more unsubstantial tail, as that is
+drawn through it and bent backward, as if by a wind blowing toward the
+celestial pole.
+
+The most notable feature, however, is the development of a second ray
+or spur, which has been apparently darted through millions of miles in
+the interval since we looked at it, and an almost imperceptible bending
+backward in both, as if they too felt the resistance of something in
+what we are accustomed to think of as an absolute and perfect void.
+These tails are a peculiarly mysterious feature. They are apparently
+shot out in a direction opposite to the sun (and consequently opposed
+to the direction of gravity) at the rate of millions of miles a day.
+
+[Illustration: FIG. 84.--COMET OF DONATI, OCT. 9, 1858.]
+
+Beyond the fact that the existence of some _repulsive_ force in the
+sun, a “negative gravity” actually existent, not in fancy, but in fact,
+seems pointed at, astronomers can offer little but conjecture here;
+and while some conceive this force as of an electrical nature, others
+strenuously deny it. We ought to admit that up to the present time we
+really know nothing about it, except that it exists.
+
+At this date (October 9th) the comet had made nearly its closest
+approach to the earth, and the general outline has been compared to
+that of the wing of some bird, while the actual size was so vast that
+even at the distance from which it was seen it filled an angle more
+than half of that from the zenith to the horizon.
+
+All the preceding drawings have been from naked-eye views; but if
+the reader would like to look more closely, he can see on page 217
+one taken on the night of October 5th through the great telescope
+at Cambridge, Mass. We will leave this to tell its own story, only
+remarking that it is not possible to reproduce the phantom-like
+faintness of the original spur, here also distinctly seen, or indeed
+to indicate fairly the infinite tenuity of the tail itself. Though
+millions of miles thick, the faintest star is yet perceptibly undimmed
+by it, and in estimating the character and quantity of matter it
+contains, after noting that it is not self-luminous, but shines
+only like the moon by reflected sunlight, we may recall the acute
+observation of Sir Isaac Newton where he compares the brightness of a
+comet’s tail with that of the light reflected from the particles in a
+sunbeam an inch or two thick, in a darkened room, and, after observing
+that if a little sphere of common air one inch in diameter were
+rarified to the degree which must obtain at only four thousand miles
+from the earth’s surface it would fill all the regions of the planets
+to far beyond the orbit of Saturn, suggests the excessively small
+quantity of vapor that is really requisite to create this prodigious
+phantom.
+
+The writer has had occasion for many years to make a special study of
+the reflection of light from the sky; and if such studies may authorize
+him to express any opinion of his own, he would give his adhesion to
+the remark of Sir John Herschel, that the actual weight of matter in
+such a cometary tail may be conceivably only an affair of pounds or
+even ounces. But if this is true of the tail, it does not follow of
+the nucleus, just seen in this picture, but of which the engraving on
+page 205 gives a much more magnified view. It is a sketch of the head
+alone, taken from a telescopic view on the 24th of September. Here the
+direction of the comet is still toward the sun (which must be supposed
+to be some indefinite distance beyond the upper part of the drawing),
+and we see that the lucid matter appears to be first jetted up, and
+then forced backward on either side, as if by a wind _from_ the sun,
+to form the tail, presenting successive crescent-shaped envelopes of
+decreasing brightness, which are not symmetrical, but one-sided, while
+sometimes the appearance is that of spurts of luminous smoke, wavering
+as if thrown out of particular parts of the internal nucleus “like a
+squib not held fast.” Down the centre of the tail runs a wonderfully
+straight black line, like a shadow cast from the nucleus. Only the
+nucleus itself still evades us, and even in this, the most magnified
+view which the most powerful telescope till lately in existence could
+give, remains a point.
+
+Considering the distance of the comet and the other optical conditions,
+this is still perfectly consistent with the possibility that it may
+have an actual diameter of a hundred miles or more. It “may” have,
+observe, not it “has,” for in fact we know nothing about it; but that
+it is at any rate less than some few hundred miles in diameter, and it
+may, for anything we can positively say, not be more than a very large
+stone, in which case our atmosphere would probably act as an efficient
+buffer if it struck us; or it may have a mass which, coupled with its
+terrible speed, would cause the shock of its contact not so much to
+pulverize the region it struck, as dissipate it and everything on it
+instantly into vapor.
+
+[Illustration: FIG. 85.--COMET OF DONATI, OCT. 5, 1858. (TELESCOPIC
+VIEW.)]
+
+Of the remarkable investigations of the spectroscope on comets, we
+have only room left to say that they inform us that the most prominent
+cometary element seems to be carbon,--carbon, which Newton two hundred
+years before the spectroscope, and before the term “carbonic-acid gas”
+was coined, by some guess or divination had described in other words
+as possibly brought to us by comets to keep up the carbonic-acid-gas
+supply in our air,--carbon, which we find in our own bodies, and of
+which, according to this view, the comets are original sources.
+
+That _we_ may be partly made of old and used-up comets,--surely it
+might seem that a madder fancy never came from the brain of a lunatic
+at the full of the moon!
+
+Science may easily be pardoned for not giving instant reception to such
+an idea, but let us also remember, first, that it is a consequence of
+that of Sir Isaac Newton, and that in the case of such a man as he
+we should not be hasty to think we understand his ignorance, when we
+may be “ignorant of his understanding;” and, second, that it has been
+rendered at least debatable by Dr. Hunt’s recent researches whether
+it is possible to account for the perennial supply of carbon from the
+earth’s atmosphere, without looking to some means of renewal external
+to the planet.
+
+The old dread of comets is passing away, and all that science has
+to tell us of them indicates that, though still fruitful sources of
+curiosity and indeed of wonder, they need no longer be objects of
+terror. Though there be, as Kepler said, more comets in the sky than
+fish in the ocean, the encounter of the earth with a comet’s tail would
+be like the encounter with a shadow, and the chance of a collision
+with the nucleus is remote indeed. We may sleep undisturbed even if
+a new comet is announced every month, though it is true that here as
+elsewhere lie remote possibilities of evil.
+
+The consideration of the unfamiliar powers certainly latent in Nature,
+such as belong to a little tremor of the planet’s surface or such
+as was shown in that scene I have described, when the comparatively
+insignificant effect of the few tons of dynamite was to make solid
+buildings unrealities, which vanished away as quickly as magic-lantern
+pictures from a screen, may help us to understand that the words of
+the great poet are but the possible expression of a physical fact,
+and that “the cloud-capped towers, the gorgeous palaces, the solemn
+temples,”--and we with them,--may indeed conceivably some day vanish
+as the airy nothings at the touch of Prospero’s wand, and without the
+warning to us of a single instant that the security of our ordinary
+lives is about to be broken. We concede this, however, in the present
+case only as an abstract possibility; for the advance of astronomical
+knowledge is much more likely to show that the kernel of the comet
+is but of the bigness of some large meteorite, against which our air
+is an efficient shield, and the chance of evil is in any case most
+remote,--in any case only such as may come in any hour of our lives
+from any quarter, not alone from the earthquake or the comet, but
+from “the pestilence that walketh in darkness;” from the infinitely
+little below and within us, as well as from the infinite powers of the
+universe without.
+
+
+
+
+VIII.
+
+THE STARS.
+
+
+In the South Kensington Museum there is, as everybody knows, an immense
+collection of objects, appealing to all tastes and all classes, and
+we find there at the same time people belonging to the wealthy and
+cultivated part of society lingering over the Louis Seize cabinets or
+the old majolica, and the artisan and his wife studying the statements
+as to the relative economy of baking-powders, or admiring Tippoo Saib’s
+wooden tiger.
+
+There is one shelf, however, which seems to have some attraction common
+to all social grades, for its contents appear to be of equal interest
+to the peer and the costermonger. It is the representation of a _man_
+resolved into his chemical elements, or rather an exhibition of the
+materials of which the human body is composed. There is a definite
+amount of water, for instance, in our blood and tissues, and there on
+the shelf are just so many gallons of water in a large vessel. Another
+jar shows the exact quantity of carbon in us; smaller bottles contain
+our iron and our phosphorus in just proportion, while others exhibit
+still other constituents of the body, and the whole reposes on the
+shelf as if ready for the coming of a new Frankenstein to re-create
+the original man and make him walk about again as we do. The little
+vials that contain the different elements which we all bear about in
+small proportions are more numerous, and they suggest, not merely the
+complexity of our constitutions, but the identity of our elements with
+those we have found by the spectroscope, not alone in the sun, but even
+in the distant stars and nebulæ; for this wonderful instrument of the
+New Astronomy can find the traces of poison in a stomach or analyze
+a star, and its conclusions lead us to think that the ancients were
+nearly right when they called man a microcosm, or little universe. We
+have literally within our own bodies samples of the most important
+elements of which the great universe without is composed; and you and I
+are not only like each other, and brothers in humanity, but children of
+the sun and stars in a more literal sense, having bodies actually made
+in large part of the same things that make Sirius and Aldebaran. They
+and we are near relatives.
+
+[Illustration: FIG. 86.--TYPES OF STELLAR SPECTRA.]
+
+But if near in kind, we are distant relatives in another way, for the
+sun, whose remoteness we have elsewhere tried to give an idea of, is
+comparatively close at hand; quite at hand, one may say, for if his
+distance, which we have found so enormous, be represented by that
+of a man standing so close beside us that our hand may rest on his
+shoulder, to obtain the proportionate distance of one of the _nearest_
+stars, like Sirius, for instance, we should need to send the man over
+a hundred miles away. It is probably impossible to give to any one an
+adequate idea of the extent of the sidereal universe; but it certainly
+is especially hard for the reader who has just realized with difficulty
+the actual immensity of the distance of the sun, and who is next told
+that this distance is literally a physical point as seen from the
+nearest star. The jaded imagination can be spurred to no higher flight,
+and the facts and the enormous numbers that convey them will not be
+comprehended.
+
+Look down at one of the nests of those smallest ants, which are made
+in our paths. To these little people, we may suppose, the other side
+of the gravel walk is the other side of the world, and the ant who
+has been as far as the gate, a greater traveller than a man who comes
+back from the Indies. It is very hard to think not only of ourselves
+as relatively far smaller than such insects, but that, less than such
+an ant-hill is to the whole landscape, is our solar system itself in
+comparison with the new prospect before us; yet so it is.
+
+All greatness and littleness are relative. When the traveller from the
+great star Sirius (where, according to the author of “Micromegas,”
+all the inhabitants are proportionately tall and proportionately
+long-lived), discovered our own little solar system, and lighted on
+what we call the majestic planet Saturn, he was naturally astonished at
+the pettiness of everything compared with the world he had left. That
+the Saturnian inhabitants were in his eyes a race of mere dwarfs (they
+were only a mile high, instead of twenty-four miles like himself) did
+not make them contemptible to his philosophic mind, for he reflected
+that such little creatures might still think and reason; but when he
+learned that these puny beings were also correspondingly short-lived,
+and passed but fifteen thousand years between the cradle and the
+grave, he could not but agree that this was like dying as soon as one
+was born, that their life was but a span, and their globe an atom. Yet
+it seems that when one of these very Saturnian dwarfs came afterward
+with him to our own little ball, and by the aid of a microscope
+discovered certain animalculæ on its surface, and even held converse
+with two of them, he could not in turn make up his own mind that
+intelligence could inhere in such invisible insects, till one of them
+(it was an astronomer with his sextant) measured his height to an inch,
+and the other, a divine, expounded to him the theology of some of these
+mites, according to which all the heavenly host, including Saturn and
+Sirius itself, were created for _them_.
+
+Do not let us hold this parable as out of place here, for what use is
+it to write down a long series of figures expressing the magnitude of
+other worlds, if it leave us with the old sense of the importance to
+creation of our own; and what use to describe their infinite number to
+a human mite who reads, and remains of the opinion that _he_ is the
+object they were all created for?
+
+Above us are millions of suns like ours. The Milky Way (shown on page
+225) spreads among them, vague and all-surrounding, as a type of the
+infinities yet unexplored, and of the world of nebulæ of which we
+still know so little. Let us say at once that it is impossible here to
+undertake the description of the discoveries of the New Astronomy in
+this region, for we can scarcely indicate the headings of the chapters
+which would need to be written to describe what is most important.
+
+[Illustration: FIG. 87.--THE MILKY WAY. (FROM A STUDY BY E. L.
+TROUVELOT).]
+
+The first of these chapters (if we treated our subjects in the order of
+distance) would be one on space itself, and our changed ideas of the
+void which separates us from the stars. Of this we will only say in
+passing, that the old term “the temperature of space” has been nearly
+abrogated; for while it used to be supposed that more than half of
+the heat which warmed the earth came from this mysterious “space”
+or from the stars, it is now recognized that the earth is principally
+warmed only by the sun. Of the contents of the region between the
+earth and the stars, we have, it must be admitted, still little but
+conjecture; though perhaps that conjecture turns more than formerly to
+the idea that the void is not a real void, but that it is occupied by
+something which, if highly attenuated, is none the less matter, and
+something other and more than the mere metaphysical conception of a
+vehicle to transmit light to us.
+
+Of the stars themselves, we should need another chapter to tell what
+has been newly learned as to their color and light, even by the old
+methods, that is, by the eye and the telescope alone; but if we
+cannot dwell on this, we must at least refer, however inadequately,
+to what American astronomers are doing in this department of the New
+Astronomy, and first in the photometry of the stars, which has assumed
+a new importance of late years, owing to the labors carried on in this
+department at Cambridge.
+
+That one star differs from another star in glory we have long heard,
+but our knowledge of physical things depends largely on our ability
+to answer the question, “how much?” and the value of this new work
+lies in the accuracy and fulness of its measures; for in this case the
+whole heavens visible from Cambridge to near the southern horizon have
+been surveyed, and the brightness of every naked-eye star repeatedly
+measured, so that all future changes can be noted. This great work has
+taxed the resources of a great observatory, and its results are only to
+be adequately valued by other astronomers; but Professor Pickering’s
+own investigations on variable stars have a more popular interest. It
+is surely an amazing fact that suns as large or larger than our own
+should seem to dwindle almost to extinction, and regain their light
+within a few days or even hours; yet the fact has long been known,
+while the cause has remained a mystery. A mystery, in most cases, it
+remains still; but in some we have begun to get knowledge, as in the
+well-known instance of Algol, the star in the head of Medusa. Here it
+has always been thought probable that the change was due to something
+coming between us and the star; but it is on this very account that
+the new investigation is more interesting, as showing how much can be
+done on an old subject by fresh reasoning alone, and how much valuable
+ore may lie in material which has already been sifted. The discussion
+of the subject by Professor Pickering, apart from its elevated aim,
+has if, in its acute analysis only, the interest belonging to a story
+where the reader first sees a number of possible clews to some mystery,
+and then the gradual setting aside, one by one, of those which are
+only loose ends, and the recognition of the real ones which lead to
+the successful solution. The skill of the novelist, however, is more
+apparent than real, since the riddle he solves for us is one he has
+himself constructed, while here the enigma is of Nature’s propounding;
+and if the solution alone were given us, the means by which it is
+reached would indeed seem to be inexplicable.
+
+This is especially so when we remember what a point there is to work
+on, for the whole system reasoned about, though it may be larger than
+our own, is at such a distance that it appears, literally and exactly,
+far smaller to the eye than the point of the finest sewing-needle;
+and it is a course of accurate reasoning, and reasoning alone, on
+the character of the observed changing brightness of this point,
+which has not only shown the existence of some great dark satellite,
+but indicated its size, its distance from its sun, its time of
+revolution, the inclination of its orbit, and still more. The existence
+of dark invisible bodies in space, then, is in one case at least
+demonstrated, and in this instance the dark body is of enormous size;
+for, to illustrate by our own solar system, we should probably have
+to represent it in imagination by a planet or swarm of planetoids
+hundreds of times the size of Jupiter, and (it may be added) whirling
+around the sun at less than a tenth the distance of Mercury.
+
+Of a wholly different class of variables are those which have till
+lately only been known at intervals of centuries, like that new star
+Tycho saw in 1572. I infer from numerous inquiries that there is such a
+prevalent popular notion that the “Star of Bethlehem” may be expected
+to show itself again at about the present time, that perhaps I may be
+excused for answering these questions in the present connection.
+
+In the first place, the idea is not a new, but a very old one, going
+back to the time of Tycho himself, who disputed the alleged identity
+of his star with that which appeared to the shepherds at the Nativity.
+The evidence relied on is, that bright stars are said to have appeared
+in this constellation repeatedly at intervals of from three hundred
+and eight to three hundred and nineteen years (though even this is
+uncertain); and as the mean of these numbers is about three hundred and
+fourteen, which again is about one-fifth of 1572 (the then number of
+years from the birth of Christ), it has been suggested, in support of
+the old notion, that the Star of Bethlehem might have been a variable,
+shining out every three hundred and fourteen or three hundred and
+fifteen years, whose fifth return would fall in with the appearance
+that Tycho saw, and whose _sixth_ return would come in 1886 or 1887.
+This is all there is about it, and there is nothing like evidence,
+either that this was the star seen by the Wise Men, or that it is to
+be seen again by us. On the other hand, nothing in our knowledge, or
+rather in our ignorance, authorizes us to say positively it cannot
+come again; and it may be stated for the benefit of those who like to
+believe in its speedy return, that if it does come, it will make its
+appearance some night in the northern constellation of Cassiopeia’s
+chair, the position originally determined by Tycho at its last
+appearance, being twenty-eight degrees and thirteen minutes from the
+pole, and twenty-six minutes in right ascension.
+
+We were speaking of these new stars as having till lately only appeared
+at intervals of centuries; but it is not to be inferred that if they
+now appear oftener it is because there are more of them. The reason
+is, that there are more persons looking for them; and the fact is
+recognized that, if we have observers enough and look closely enough,
+the appearance of “new stars” is not so very rare a phenomenon. Every
+one at all interested in such matters remembers that in 1866 a new
+star broke out in the Northern Crown so suddenly that it was shining
+as bright as the Polar Star, where six hours before there had been
+nothing visible to the eve. Now all stars are not as large as our sun,
+though some are much larger; but there are circumstances which make
+it improbable that this was a small or near object, and it is well
+remembered how the spectroscope showed the presence of abnormal amounts
+of incandescent hydrogen, the material which is perhaps the most
+widely diffused in the universe (and which is plentiful, too, in our
+own bodies), so that there was some countenance to the popular notion
+that this was a world in flames. We were, at any rate, witnessing a
+catastrophe which no earthly experience can give us a notion of, in a
+field of action so remote that the flash of light which brought the
+news was unknown years on the way, so that all this--strange but now
+familiar thought--occurred long before we _saw_ it happen. The star
+faded in a few days to invisibility to the naked eye, though not to the
+telescope; and, in fact, all these phenomena at present appear rather
+to be enormous and sudden enlargements of the light of existing bodies
+than the creation of absolutely new ones; while of these “new stars”
+the examples may almost be said to be now growing numerous, two having
+appeared in the last two years.
+
+Not to enlarge, then, on this chapter of photometry, let us add, in
+reference to another department of stellar astronomical work, that the
+recognized master in the study of double stars the world over is not an
+astronomer by profession, at the head of some national observatory in
+Berlin or Paris, but a stenographer in the Chicago law-courts, Mr. W.
+S. Burnham, who, after his day’s duties, by nightly labor, prolonged
+for years with the small means at an amateur’s command, has perhaps
+added more to our knowledge of his special subject in ten years than
+all other living astronomers.
+
+[Illustration: FIG. 88.--SPECTRA OF STARS IN PLEIADES.]
+
+We have here only alluded to the spectroscope in its application to
+stellar research, and we cannot now do more than to note the mere
+headlines of the chapters that should be written on it.
+
+First, there is the memorable fact that, after reaching across the
+immeasurable distances, we find that the stars are like _us_,--like in
+their ultimate elements to those found in our own sun, our own earth,
+our own bodies. Any fuller view of the subject than that which we here
+only indicate, would begin with the evidence of this truth, which is
+perhaps on the whole the most momentous our science has brought us, and
+with which no familiarity should lessen our wonder, or our sense of its
+deep and permanent significance.
+
+Next, perhaps, we should understand that, invading the province of the
+Old Astronomy, the spectroscope now tells us of the motions of these
+stars, which we cannot see move,--motions in what we have always called
+the “fixed” stars, to signify a state of fixity to the human eye, which
+is such, that to it at the close of the nineteenth century they remain
+in the same relative positions that they occupied when that eye first
+looked on them, in some period long before the count of centuries began.
+
+In perhaps the earliest and most enduring work of man’s hands, the
+great pyramid of Egypt, is a long straight shaft, cut slopingly through
+the solid stone, and pointing, like a telescope, to the heavens near
+the pole. If we look through it now we see--nothing; but when it was
+set up it pointed to a particular star which is no longer there. That
+pyramid was built when the savages of Britain saw the Southern Cross
+at night; and the same slow change in the direction of the earth’s
+axis, that in thousands of years has borne that constellation to
+southern skies, has carried the stone tube away from the star that it
+once pointed at. The actual motion of the star itself, relatively to
+our system, is slower yet,--so inconceivably slow that we can hardly
+realize it by comparison with the duration of the longest periods
+of human history. The stone tube was pointed at the star by the old
+Egyptians, but “Egypt itself is now become the land of obliviousness,
+and doteth. Her ancient civility is gone, and her glory hath vanished
+as a phantasma. She poreth not upon the heavens, astronomy is dead unto
+her, and knowledge maketh other cycles. Canopus is afar off, Memnon
+resoundeth not to the Sun, and Nilus heareth strange voices.” In all
+this lapse of ages, the star’s own motion could not have so much as
+carried it across the mouth of the narrow tube. Yet a motion to or
+from us of this degree, so slow that the unaided eve could not see it
+in thousands of years of watching, the spectroscope, first efficiently
+in the hands of the English astronomer, Dr. Huggins, and later in
+those of Professor Young of Princeton, not only reveals at a look, but
+tells us the amount and direction of it, in a way that is as strange
+and unexpected, in the view of our knowledge a generation ago, as its
+revelation of the essential composition of the bodies themselves.
+
+[Illustration: FIG. 89.--SPECTRUM OF ALDEBARAN.]
+
+[Illustration: FIG. 90.--SPECTRUM OF VEGA.]
+
+Again, in showing us this composition, it has also shown us more, for
+it has enabled us to form a conjecture as to the relative ages of the
+stars and suns; and this work of classifying them, not only according
+to their brightness, but each after his kind, we may observe was
+begun by a countryman of our own, Mr. Rutherfurd, who seems to have
+been among the first after Fraunhofer to apply the newly-invented
+instrument to the stars, and quite the first to recognize that these
+were, broadly speaking, divisible into a few leading types, depending
+not on their size but on their essential nature. After him Secchi
+(to whom the first conception is often wrongly attributed) developed
+it, and gave four main classes into which the stars are in this way
+divisible, a classification which has been much extended by others;
+while the first carefully delineated spectra were those of Dr. Huggins,
+who has done so much for all departments of our science that in a
+fuller account his name would reappear in every chapter of this New
+Astronomy, and than whom there is no more eminent living example of
+its study. Owing to their feeble light, years were needed when he
+began his work to depict completely so full a single spectrum as that
+he gives of Aldebaran, though he has lived to see stellar spectrum
+photography, whose use he first made familiar, producing in its
+newest development, which we give here, the same result in almost as
+many minutes. Before we present this latest achievement of celestial
+photography, let us employ the old method of an engraving made from
+eye-drawings, once more, to illustrate on page 222 the distinct
+character of these spectra, and their meaning. In the telespectroscope,
+the star is drawn out into a band of colored light, but here we note
+only in black and white the lines which are seen crossing it, the
+red end in these drawings being at the left, and the violet at the
+right; and we may observe of this illustration, that though it may
+be criticised by the professional student, and though it lack to the
+general reader the attraction of color, or of beautiful form, it is
+yet full of interest to any one who wishes to learn the meaning of the
+message the star’s light can be made to yield through the spectroscope,
+and to know how significant the differences are it indicates between
+one star and another, where all look so alike to the eye. First is
+the spectrum of a typical white or blue-white star, Sirius,--the very
+brightest star in the sky, and which we all know. The brighter part
+of the spectrum is a nearly continuous ribbon of color, crossed by
+conspicuous, broad, dark lines, exactly corresponding in place to
+narrower ones in our sun, and due principally to hydrogen. Iron and
+magnesium are also indicated in this class, but by too fine lines to be
+here shown.
+
+Sirius, as will be presently seen, belongs to the division of stars
+whose spectrum indicates a very high temperature, and in this case, as
+in what follows, we may remark (to use in part Mr. Lockyer’s words)
+that one of the most important distinctions between the stars in the
+heavens is one not depending upon their mass or upon anything of that
+kind, but upon conditions which make their spectra differ, just in the
+way that in our laboratories the spectrum of one and the same body will
+differ at different temperatures.
+
+What these absolutely are in the case of the stars, we may not
+know; but placing them in their most probable relative order, we
+have taken as an instance of the second class, or lower-temperature
+stage, our own sun. The impossibility of giving a just notion of its
+real complexity may be understood, when we state that in the recent
+magnificent photographs by Professor Rowland, a part alone of this
+spectrum occupies something like fifty times the space here given to
+the whole, so that, crowded with lines as this appears, scarcely one
+in fifty of those actually visible can be given in it. Without trying
+to understand all these now, let us notice only the identity of two
+or three of its principal elements with those found in other stars,
+as shown by the corresponding identity of some leading lines. Thus, C
+and F (with others) are known to be caused by hydrogen; D, by sodium;
+_b_, by magnesium; while fainter lines are given by iron and by other
+substances. These elements can be traced by their lines in most of
+the different star-spectra on this plate, and all those named are
+constituents of our own frames.
+
+The hydrogen lines are not quite accurately shown in the plate from
+which our engraving is made, those in Sirius, for instance, being
+really wider by comparison than they are here given; and we may observe
+in this connection, that by the particular appearance such lines wear
+in the spectrum itself we can obtain some notion of the _mass_ of a
+star, as well as of its chemical constitution. We can compare the
+essential characteristics of such bodies, then, without reference
+to their apparent size, or as though they were all equally remote;
+and it is a striking thought, that when we thus rise to an impartial
+contemplation of the whole stellar universe, our sun, whose least ray
+makes the whole host of stars disappear, is found to be not only
+itself a star, but by comparison a small one,--one at least which is
+more probably below than above the average individual of its class,
+while some, such as Sirius, are not impossibly hundreds of times its
+size.
+
+Then comes a third class, such as is shown in the spectrum of the
+brightest star in Orion, looking still a little like that of our sun;
+but yet more distinctively in that of the brightest star in Hercules,
+looking like a columnar or fluted structure, and concerning which the
+observations of Lockyer and others create the strong presumption, not
+to say certainty, that we have here a lower temperature still. Antares
+and other reddish stars belong to this division, which in the very
+red stars passes into the fourth type, and there are more classes and
+subclasses without end; but we invite here attention particularly to
+the first three, much as we might present a child, an adult, and an
+old man, as types of the stages of human existence, without meaning to
+deny that there are any number of ages between. We can even say that
+this may be something more than a mere figure of speech, and that a
+succession in age is not improbably pointed at in these types.
+
+[Illustration: FIG. 91.--GREAT NEBULA IN ORION. (FROM A PHOTOGRAPH BY
+A. A. COMMON, F. R. S.)]
+
+We may have considered--perhaps not without a sort of awe at the
+vastness of the retrospect--the past life of the worlds of our own
+system, from our own globe of fluid fire as we see it by analogy in
+the past, through the stages of planetary life to the actual condition
+of our present green earth, and on to the stillness of the moon. Yet
+the life history of our sun, we can hardly but admit, is indefinitely
+longer than this. We feel, rather than comprehend, the vastness of
+the period that separates our civilization from the early life of the
+world; but what is this to the age of the sun, which has looked on and
+seen its planetary children grow? Yet if we admit this temperature
+classification of the stars, we are not far from admitting that the
+spectroscope is now pointing out the stages in the life of suns
+themselves; suns just beginning their life of almost infinite years;
+suns in the middle of their course; suns which are growing old and
+casting feebler beams,--all these and many more it brings before us.
+
+Another division of our subject would, with more space, include a
+fuller account of that strange and most interesting development of
+photography which is going on even while we write; and this is so new
+and so important, that we must try to give some hint of it even in
+this brief summary, for even since the first numbers of this series
+were written, great advances have taken place in its application to
+celestial objects.
+
+Most of us have vague ideas about small portions of time; so much so,
+that it is rather surprising to find to how many intelligent people, a
+second, as seen on the clock face, is its least conceivable interval.
+Yet a second has not only a beginning, middle, and end, as much as a
+year has, but can, in thought at least, be divided into just as many
+numbered parts as a year can. Without entering on a disquisition about
+this, let us try to show by some familiar thing that we can at any rate
+not only divide a second in imagination into, let us say, a hundred
+parts, but that we can observe distinctly what is happening in such a
+short time, and make a picture of it,--a picture which shall be begun
+and completed while this hundredth of a second lasts.
+
+Every one has fallen through at least some such a little distance as
+comes in jumping from a chair to the floor, and most of us, it is safe
+to say, have a familiar impression of the fact that it takes, at any
+rate, less than a second in such a case from the time the foot leaves
+its first support till it touches the ground. Plainly, however large or
+small the fall may be, each fraction of an inch of it must be passed
+through in succession, and if we suppose the space to be divided,
+for instance, into a hundred parts, we must divide in thought the
+second into at least as many, since each little successive space was
+traversed in its own little interval of time, and the whole together
+did not make a second. We can even, as a matter of fact, very easily
+calculate the time that it will take anything which has already fallen,
+let us say one foot, to fall an inch more; and we find this, in the
+supposed instance, to be almost exactly one one-hundredth of a second.
+On page 243 is a reproduction of a photograph from Nature, of a man
+falling freely through the air. He has dropped from the grasp of the
+man above him, and has already fallen through some small distance,--a
+foot or so. If we suppose it to be a foot, since we can see that the
+man’s features are not blurred, as they would undoubtedly have been
+had he moved even much less than an inch while this picture was being
+taken, it follows, from what has been said, that the making of the
+whole picture--landscape, spectators, and all--occupied not _over_ one
+one-hundredth of a second.
+
+We have given this view of “the falling man” because, rightly
+understood, it thus carries internal evidence of the limit of time in
+which it could have been made; and this will serve as an introduction
+to another picture, where probably no one will dispute that the time
+was still shorter, but where we cannot give the same kind of evidence
+of the fact.
+
+“Quick as lightning” is our common simile for anything occupying,
+to ordinary sense, no time at all. Exact measurements show that the
+electric spark does occupy a time, which is almost inconceivably small,
+and of which we can only say here that the one one-hundredth of a
+second we have just been considering is a long period by comparison
+with the duration of the brightest portion of the light.
+
+[Illustration: FIG. 92.--A FALLING MAN.]
+
+On page 245 we have the photograph of a flash of lightning (which
+proves to be several simultaneous flashes), taken last July from a
+point on the Connecticut coast, and showing not only the vivid zigzag
+streaks of the lightning itself, but something of the distant sea
+view, and the masts of the coast survey schooner “Palinurus” in the
+foreground, relieved against the sky. We are here concerned with this
+interesting autograph of the lightning, only as an illustration of our
+subject, and as proving the almost infinite sensitiveness of the recent
+photographic processes; for there seems to be no limit to the briefness
+of time in which, these can so act in some degree, whether the light be
+bright or faint, and no known limit to the briefness of time required
+for them to act _effectively_ if the light be bright enough.
+
+What has just preceded will now help us to understand how it is that
+photography also succeeds so well in the incomparably fainter objects
+we are about to consider, and which have been produced not by short but
+by long exposures. We have just seen how sensitive the modern plate
+is, and we are next to notice a new and very important point in which
+photographic action in general differs remarkably from that of the eye.
+Seeing may be described, not wholly inaptly, as the recognition of a
+series of brief successive photographs, taken by the optic lens on the
+retina; but the important difference between seeing and photographing,
+which we now ask attention to, is this: When the eye looks at a faint
+object, such as the spectrum of a star, or at the still fainter nebula,
+this, as we know, appears no brighter at the end of half an hour than
+at the end of the first half-second. In other words, after a brief
+fraction of a second, the visual effect does not sensibly accumulate.
+But in the action of the photograph, on the contrary, the effect _does_
+accumulate, and in the case of a weak light accumulates indefinitely.
+It is owing to this precious property, that supposing (for illustration
+merely) the lightning flash to have occupied the one-thousandth part
+of a second in impressing itself on the plate, to get a nearly similar
+effect from a continuous light one thousand times weaker, we have only
+to expose the ¡date a thousand times as long, that is, for one second;
+while from a light a million times weaker we should get the same
+result by exposing it a million times as long, that is, for a thousand
+seconds.
+
+And now that we come to the stars, whose spectra occupy minutes in
+taking, what we just considered will help us to understand how we can
+advantageously thus pass from a thousandth of a second or less, to
+one thousand seconds or even more, and how we can even,--given time
+enough,--conceivably, be able to photograph what the eye _cannot see at
+all_.
+
+[Illustration: FIG. 93.--A FLASH OF LIGHTNING. (FROM A PHOTOGRAPH BY
+DR. H. G. PIFFARD.)]
+
+We have on page 231 a photograph quite recently taken at Cambridge from
+a group of stars (the Pleiades) passing by the telescope. Every star
+is caught as it goes, and presented, not in its ordinary appearance to
+the eye, but by its spectrum. There is a general resemblance in these
+spectra from the same cluster; while in other cases the spectra are
+of all types and kinds, the essential distinction between individuals
+alike to the eve, being more strikingly shown, as stars apparently
+far away from one another are seen to have a common nature, and stars
+looking close together (but which may be merely in line, and really far
+apart) have often no resemblance; and so the whole procession passes
+through the field of view, each individual leaving its own description.
+This self-description will be better seen in the remarkable photographs
+of the spectra of Vega and Aldebaran, which are reproduced on page 235
+from the originals by a process independent of the graver. They were
+obtained on the night of November 9, 1886, at Cambridge, as a part of
+the work pursued by Professor Pickering, with means which have been
+given from fitting hands, thus to form a memorial of the late Dr. Henry
+Draper. We are obliged to the source indicated, then, for the ability
+to show the reader here the latest, and as yet inedited, results in
+this direction; and they are such as fully to justify the remark made
+above, that minutes, by this new process, take the place of years of
+work by the most skilful astronomer’s eye and hand.
+
+The spectrum of Vega (Alpha Lyræ) is marked only by a few strong lines,
+due chiefly to hydrogen, because these are all there are to be seen
+in a star of its class. Aldebaran (the bright star in Taurus), on the
+contrary, here announces itself as belonging to the family of our own
+sun, a probably later type, and distinguished by solar-like lines in
+its spectrum, which may be counted in the original photograph to the
+number of over two hundred. There is necessarily some loss in the
+printed reproduction; but is it not a wonderful thing, to be able to
+look up, as the reader may do, to Aldebaran in the sky, and then down
+upon the page before us, knowing that that remote, trembling speck of
+light has by one of the latest developments of the New Astronomy been
+made, without the intervention of the graver’s hand, to write its own
+autograph record on the page before him?
+
+In the department of nebular astronomy, photography has worked an equal
+change. The writer well remembers the weeks he has himself spent in
+drawing or attempting to draw nebulæ,--things often so ghost-like as
+to disappear from view every time the eye turned from the white paper,
+and only to be seen again when it had recovered its sensitiveness by
+gazing into the darkness. The labors of weeks were, literally, only
+represented by what looked like a stain on the paper; and no two
+observers, however careful, could be sure that the change between
+two drawings of a nebula at different dates was due to an alteration
+in the thing itself, or in the eye or hand of the observer, though
+unfortunately for the same reason it is impossible fully to render the
+nebulous effect of the photograph in engraving. We cannot with our
+best efforts, then, do full justice to the admirable one of Orion, on
+page 239, which we owe to the particular kindness of Mr. Common, of
+Ealing, England, whose work in this field is as yet unequalled. The
+original enlargement measures nearly two square feet in area, with
+fine definition. It is taken by thirty-nine minutes’ exposure, and its
+character can only be indicated here; for it is not too much to say
+here of this original also, that as many years of the life of the most
+skilled artist could not produce so trustworthy a record of this wonder.
+
+The writer remembers the interest with which he heard Dr. Draper,
+not long before his lamented death, speak of the almost incredible
+sensitiveness of these most recent photographic processes, and his
+belief that we were fast approaching the time when we should photograph
+what we could not even see. That time has now arrived. At Cambridge,
+in Massachusetts, and at the Paris Observatory, by taking advantage
+of the cumulative action we have referred to, and by long exposures,
+photographs have recently been taken showing stars absolutely invisible
+to the telescope, and enabling us to discover faint nebulæ whose
+previous existence had not been suspected; and when we consider that an
+hour’s exposure of a plate, now not only secures a fuller star-chart
+than years of an astronomer’s labor, but a more exact one, that the
+art is every month advancing perceptibly over the last, and that it is
+already, as we may say, not only making pictures of what we see, but
+of what we cannot see even with the telescope,--we have before us a
+prospect whose possibilities no further words are needed to suggest.
+
+We have now, not described, but only mentioned, some division of the
+labors of the New Astronomy in its photometric, spectroscopic, and
+photographic stellar researches, on each of which as many books, rather
+than chapters, might be written, to give only what is novel and of
+current interest. But these are themselves but a part of the modern
+work that has overturned or modified almost every conception about the
+stellar universe which was familiar to the last generation, or which
+perhaps we were taught in our own youth.
+
+       *       *       *       *       *
+
+In considering the results to be drawn from this glance we have taken
+at some facts of modern observation, if it be asked, not only what
+the facts are, but what lessons the facts themselves have to teach,
+there is more than one answer, for the moral of a story depends on
+the one who draws it, and we may look on our story of the heavens
+from the point of view either of our own importance or of our own
+insignificance. In the one case we behold the universe as a sort of
+reflex of our own selves, mirroring in vast proportions of time and
+space our own destiny; and even from this standpoint, one of the
+lessons of our subject is surely that there is no permanence in any
+created thing. When primitive man learned that with lapsing years the
+oak withered and the very rock decayed, more slowly but as surely as
+himself, he looked up to the stars as the types of contrast to the
+change he shared, and fondly deemed them eternal; but now we have found
+change there, and that probably the star clusters and the nebulæ, even
+if clouds of suns and worlds, are fixed only by comparison with our own
+brief years, and, tried by the terms of their own long existence, are
+fleeting like ourselves.
+
+  “We have often witnessed the formation of a cloud in a serene
+  sky. A hazy point barely perceptible--a little wreath of mist
+  increases in volume and becomes darker and denser, until it
+  obscures a large portion of the heavens. It throws itself into
+  fantastic shapes, it gathers a glory from the sun, is borne
+  onward by the wind, and as it gradually came, so, perhaps, it
+  gradually disappears, melting away in the untroubled air. But the
+  universe is nothing more than such a cloud,--a cloud of suns and
+  worlds. Supremely grand though it may seem to us, to the infinite
+  and eternal intellect it is no more than a fleeting mist. If
+  there be a succession of worlds in infinite space, there is also
+  a succession of worlds in infinite time. As one after another
+  cloud replaces clouds in the skies, so this starry system, the
+  universe, is the successor of countless others that have preceded
+  it,--the predecessor of countless others that will follow.”
+
+These impressions are strengthened rather than weakened when we come
+back from the outer universe to our own little solar system; for
+every process which we know, tends to the dissipation, or rather the
+degradation, of heat, and seems to point, in our present knowledge, to
+the final decay and extinction of the light of the world. In the words
+of one of the most eminent living students of our subject, “The candle
+of the sun is burning down, and, as far as we can see, must at last
+reach the socket. Then will begin a total eclipse which will have no
+end.
+
+    ‘Dies iræ, dies illa,
+    Solvet sæclum in favilla.’”
+
+Yet though it may well be that the fact itself here is true,
+it is possible that we draw the moral to it, unawares, from an
+unacknowledged satisfaction in the idea of the vastness of the funeral
+pyre provided for such beings as ourselves, and that it is pride,
+after all, which suggests the thought that when the sun of the human
+race sets, the universe will be left tenantless, as a body from which
+the soul has fled. Can we not bring ourselves to admit that there may
+be something higher than man and more enduring than frail humanity,
+in some sphere in which _our_ universe, conditioned as it is in space
+and time, is itself embraced; and so distrust the conclusions of man’s
+reason where they seem to flatter his pride?
+
+May we not receive even the teachings of science, as to the “Laws of
+Nature,” with the constant memory that all we know, even from science
+itself, depends on our very limited sensations, our very limited
+experience, and our still more limited power of conceiving anything for
+which this experience has not prepared us?
+
+       *       *       *       *       *
+
+I have read somewhere a story about a race of ephemeral insects who
+live but an hour. To those who are born in the early morning the
+sunrise is the time of youth. They die of old age while his beams are
+yet gathering force, and only their descendants live on to midday;
+while it is another race which sees the sun decline, from that which
+saw him rise. Imagine the sun about to set, and the whole nation of
+mites gathered under the shadow of some mushroom (to them ancient
+as the sun itself) to hear what their wisest philosopher has to say
+of the gloomy prospect. If I remember aright, he first told them
+that, incredible as it might seem, there was not only a time in the
+world’s youth when the mushroom itself was young, but that the sun in
+those early ages was in the eastern, not in the western, sky. Since
+then, he explained, the eyes of scientific ephemera had followed it,
+and established by induction from vast experience the great “Law of
+Nature,” that it moved only westward; and he showed that since it
+was now nearing the western horizon, science herself pointed to the
+conclusion that it was about to disappear forever, together with the
+great race of ephemera for whom it was created.
+
+What his hearers thought of this discourse I do not remember, but I
+have heard that the sun rose again the next morning.
+
+
+
+
+INDEX.
+
+
+  Abbe, Professor, 56.
+
+  Actinism, 71.
+
+  Adams, Professor, 195.
+
+  Africa, 116.
+
+  Ages, stellar, 238.
+
+  Air:
+    dancing, 17;
+    a medium, 33;
+    continuous, 176;
+    rarefied, 179;
+    motes, 181;
+    nimble, 191.
+    (See _Atmosphere_.)
+
+  Airless Mountains, 160.
+
+  Air-wave, 185.
+
+  Aitken’s Researches, 181.
+
+  Alaska, 38.
+
+  Aldebaran, 222, 235, 236, 246.
+
+  Algot, 228.
+
+  Allegheny Observatory, 17, 19, 84, 86.
+    (See _Langley_.)
+
+  Alphonsus Ring-plain, 156.
+
+  Alps, 39, 148, 151, 167, 181.
+    (See _Apennines, Lunar_.)
+
+  American Astronomers, 227.
+
+  American Continents, 20, 21, 31.
+    (See _South_.)
+
+  Andalusia, 53.
+
+  Animalculæ, 224.
+
+  Animals:
+    food, 74;
+    fright, 42.
+    (See _Dog_.)
+
+  Antares, 238.
+
+  Ants, 223.
+    (See _Insects_.)
+
+  Apennines, 151, 153, 155, 160, 167.
+    (See _Alps, Lunar_.)
+
+  Apples, 171.
+
+  Arab Traditions, 194.
+    (See _Moslem_.)
+
+  Arago, quoted, 41, 42.
+
+  Archimedes, 94.
+
+  Archimedes Crater, 151–153, 155.
+
+  Arctic Cold, 159.
+
+  Arctic Pole, 96.
+
+  Arcturus, 208, 211.
+
+  Aristillus Crater, 151.
+
+  Aristotelian Philosophy, 8.
+
+  Arzachel, 156, 161.
+
+  Asteroids, 128.
+
+  Astrology, 127.
+
+  Astronomers and Priests, 1–3.
+    (See _American, New_, _Old_.)
+
+  Astronomical Day, 85, 86.
+
+  Atmosphere, 136, 180;
+    as a shield, 216, 220.
+    (See _Air_.)
+
+  Atolls, 152.
+
+  Auger, simile, 31.
+
+  Aurora Borealis, 35, 67, 212.
+
+  Autolycus Crater, 151.
+
+  Axis, 9, 10.
+
+
+  Babel, 96.
+
+  Bain Telegraph, 88.
+
+  Balloons, 176.
+
+  Bees, 124.
+    (See _Insects_.)
+
+  Berkeley’s Theory, 70.
+
+  Berlin Observatory, 233.
+
+  Bernières’s Lens, 103.
+
+  Bessemer Steel, 104–108.
+
+  Birds, 172, 196, 197.
+    (See _Animals_.)
+
+  Black Hole, 73.
+
+  Bond, Professor, 204.
+
+  Boston, Mass., 88, 132.
+
+  Bothkamp, observations at, 66.
+
+  Breadstuffs, 78, 79.
+    (See _Grain_, _Sun-spots_, _Wheat_.)
+
+  Bridges, 20, 68.
+
+  Britain, Ancient, 1, 234.
+    (See _England_.)
+
+  British Isles, 14, 25.
+
+  Brocken Spectre, 55.
+
+  Brothers, Mr., 50.
+
+  Bubbles, 168.
+
+  Buffer, the air as a, 216, 220.
+
+  Bunsen’s Researches, 12.
+
+  Burnham, W. S., 233.
+
+  Burning-glasses, 102–104.
+
+  Burning Heat, 160, 163.
+
+
+  Cactus, 14, 24.
+
+  Calcutta, 73.
+
+  California, 151, 180.
+
+  Cambric Needle (_q. v._), experiment, 132.
+
+  Cambridge Observations, 227, 245–247.
+
+  Camera Obscura, 63.
+
+  Campanus Crater, 163, 165.
+
+  Candle, simile, 39.
+
+  Cannon-ball, 5, 38, 41, 98, 135, 186, 211.
+
+  Canopus, 234.
+
+  Carbon, 72, 73, 107, 221.
+
+  Carbonic-acid Gas, 219.
+
+  Carpenter’s Studio, 140.
+
+  Carrington’s Work, 79, 87.
+
+  Carthage, 116.
+
+  Cassini, 42.
+
+  Cassiopeia, 229.
+
+  Cataclysm, 30.
+
+  Centimetres, 93.
+
+  Chacornac’s Drawing, 33.
+
+  Chambers, on sun-spots, 80.
+
+  Charleston Earthquake (_q. v._), 42.
+
+  Chemical Elements, 221, 223.
+
+  Cherry-stone, comparison, 196.
+
+  Chicago:
+    great fire, 134;
+    astronomer, 233.
+
+  China:
+    lens, 103, 104;
+    soil, 180.
+
+  Chlorophyl, 73.
+
+  Chocolate, simile, 107.
+
+  Cholera, 80.
+
+  Chromosphere, 7;
+    clouds, 62;
+    forms, 64–68.
+
+  Cinders, 171.
+
+  Clark’s Glasses, 123.
+
+  Cliffs, 164.
+
+  Clock, 135.
+
+  Cloud-ocean, 179.
+
+  Clouds:
+    cirrous, 27, 28;
+    beautiful, 54;
+    and rain, 111;
+    formed, 249.
+
+  Coal-beds, 115.
+
+  Coal:
+    energy, 73–75, 111;
+    destroyed, 97;
+    wasted, 101;
+    stock, 112.
+
+  Cobweb, simile, 26.
+
+  Cold:
+    and eclipses, 40;
+    in planets, 136.
+
+  Colorado, 50.
+
+  Colors:
+    in eclipses (_q. v._), 65;
+    mental, 70, 71;
+    in Jupiter (_q. v._), 127;
+    in moon (_q. v._), 168;
+    in stars (_q. v._), 227;
+    spectrum (_q. v._), 236.
+
+  Comet-hunters, 204, 207.
+
+  Comets:
+    chapter, 199–220;
+    Donati’s, 201, 204, 205, 207, 209, 217;
+    one part, 203;
+    parts and name, 208;
+    tail (_q. v._), 208, 211;
+    diameter and parts, 216;
+    spectroscope, elements, dread, 219;
+    numerous, stone, 219, 220;
+    kernel, 220;
+    (1858), 213–216;
+    (1866), 200.
+
+  Common, A. A., 239, 247.
+
+  Compass, 86.
+
+  Connecticut Observations, 186, 242.
+
+  Converter, 104–108.
+
+  Coral, 151.
+
+  Corn, 111.
+    (See _Grain_.)
+
+  Corona, 7, 36, 37, 40, 41, 43, 45–52, 55, 56, 59, 60–62.
+
+  Cotton-mill, 74.
+
+  Counting, 94.
+
+  Cracks, celestial, 163.
+
+  Craters, 164.
+    (See special names.)
+
+  Crystalline Structure, 4, 23–27.
+
+  Cyclones, 24, 31, 32, 68.
+
+
+  Decay, 248, 249.
+
+  Delambre’s History, 207.
+
+  De la Rue’s Engraving, 125.
+
+  Delfthaven, 5.
+
+  Denning’s Theory, 197.
+
+  Diamonds, melted, 103.
+
+  Dies Iræ, 249.
+
+  Dipper, 207, 208.
+    (See _Great Bear_, _Polar_.)
+
+  Diurnal Oscillation, 87.
+
+  Dog, anecdote of, 42.
+    (See _Animals_.)
+
+  Donati, 201, 204, 205, 207, 209, 213, 217.
+    (See _Comets_.)
+
+  Double Stars, 233.
+
+  Draper, Professor Henry, 128, 246, 247.
+
+  Ducks, noise, 188.
+
+  Dust, 34, 100, 101, 102, 105, 197.
+
+  Dynamite, 182, 185, 220.
+
+
+  Earth:
+    relations, 3, 4;
+    description difficult, 6;
+    temperature (_q. v._), 34, 101;
+    a string of earths, 96;
+    stars like, 118;
+    seen from outside, 133–135;
+    craters, 148.
+
+  Earthquakes, 220.
+    (See _Charleston_.)
+
+  Earth-shine, 167, 172.
+
+  Eclipses:
+    total, 7, 37;
+    screen, 36;
+    three, 39, 55;
+    partial, 40;
+    singular gloom, 39–43;
+    causing fright, 43;
+    colors (_q. v._), 48, 56, 61, 65, 66;
+    (1842), 41;
+    (1857), 48;
+    (1869), 39, 40;
+    (1870), 44, 61;
+    (1871), 50, 66, 68;
+    (1878), 38, 50, 57, 58.
+    (See _Total_.)
+
+  Egypt, 116, 234.
+    (See _Pyramids_.)
+
+  Electricity, 13, 75, 76.
+
+  Electric Light, 7.
+
+  Electric Spark, 242.
+    (See _Lightning_.)
+
+  Electric Storm, 84, 85, 88.
+
+  Elizabeth, Queen, 115.
+
+  Engine-power, 98, 111.
+
+  England:
+    fleets, 2;
+    coal, 115.
+    (See _Britain_, _London_.)
+
+  Engraving, 17.
+
+  Enigma, 228.
+
+  Ephemera, 250, 251.
+
+  Equatorial Landscape, 13, 17, 18, 47.
+
+  Equatorial Telescope, 122.
+
+  Ericsson:
+    engravings, 112, 113;
+    discoveries, 163.
+
+  Eruptive Promontories, 66–68.
+
+  Etna, 164, 181.
+
+  Europe, size, 25.
+
+  Evolution, planetary, 139.
+
+  Explosive Forces, 182–194.
+
+  Eye, 71, 227.
+
+  Eye-pieces, 47, 63.
+
+
+  Fabricius’s Observations, 8.
+
+  Fact and Fancy, 175.
+
+  Factory, 73.
+
+  Faculæ, 32, 33.
+
+  Falling, 242, 243.
+
+  Falling Stars, 193.
+    (See _Meteors_, _Shooting_.)
+
+  Faraday, Michael, 76.
+
+  Fault, technical term, 156.
+
+  Faust, 139.
+
+  Faye:
+    theory, 29–32;
+    on Comets’ Tails, 212.
+
+  Fern-like Forms, 25, 26.
+
+  Filaments, 25–27, 30, 55, 56, 65, 66, 68.
+
+  Fire, in sun (_q. v._), 92.
+    (See _Flames_, _Heat_.)
+
+  Fixed Stars, 233.
+
+  Flame-like Appearances, 23, 24.
+
+  Flames, 65, 66, 69, 185.
+
+  Flashes, 189, 195.
+
+  Flax, 111.
+
+  Flowers, color (_q. v._), 70.
+    (See _Rose_, _Plants_.)
+
+  Foliage-forms, 32.
+
+  Fontenelle’s Story, 133.
+
+  Forbes’s Observations, 38, 39.
+
+  Frankenstein, 221.
+
+  Franklin’s Discoveries, 76.
+
+  Fraunhofer Studies, 235.
+
+  French Institute, 186.
+
+  Frost-crystals (_q. v._), 23.
+
+  Furnaces, 101.
+
+
+  Galileo, 8, 121–123, 139, 140.
+
+  Gas:
+    glowing, 44;
+    in sun, 60.
+
+  Gas-jets, 40, 61, 68, 88.
+
+  Gassendi’s View, 172, 173.
+
+  Gelinck’s Observations, 80.
+
+  Geminids, 196.
+
+  Genii, 193.
+
+  Geographers and Geologists, 133.
+
+  Glare, 14, 18, 62–64.
+
+  Glass:
+    spun, 26;
+    globe, 145.
+
+  Glow-worms, 7, 117.
+
+  Good Hope Observations, 80.
+
+  Gould’s Researches, 80.
+
+  Grain, prices, 77, 80, 87.
+    (See _Corn_, _Sun-spots_, _Wheat_.)
+
+  Gramarye, 92.
+
+  Grass-blades, 66, 72.
+
+  Grasses, 26.
+
+  Gravitation, 72, 203;
+    negative, 215.
+
+  Great Bear, 207.
+    (See _Dipper_, _Polar_.)
+
+  Green’s Maps, 130.
+
+  Greenwich Observatory, 2, 81, 82, 84, 85, 88, 89.
+
+  Gulliver’s Travels, 131, 132.
+    (See _Swift_.)
+
+  Gunpowder, 186.
+
+  Guns, 135.
+    (See _Cannon-ball_.)
+
+
+  Hall Island, 130.
+
+  Hall, Professor, 131.
+
+  Hand, illustration, 168.
+
+  Harkness’s Observations, 44.
+
+  Harvests, 90.
+
+  Hastings, Professor, 60.
+
+  Heat:
+    development, 13;
+    concentration, 19;
+    loss, 29;
+    confinement, 33;
+    sensation, 71;
+    vibrations, 72;
+    energy, 91;
+    amount, 92, 97;
+    computation, 94–96;
+    diminution, 101;
+    emission, 102;
+    storage, 111;
+    in sugar, 188.
+    (See _Flames_, _Sun_.)
+
+  Hecla, 164, 181.
+
+  Hedgehog-spines, simile, 68.
+
+  Helmholtz’s Estimates, 98.
+
+  Hengist and Horsa, 1.
+    (See _Britain_.)
+
+  Hercules, 238.
+
+  Herschel, Sir John:
+    sun-spots, 12–14;
+    electric storms, 88;
+    comet’s tail, 216.
+
+  Herschel, Sir William:
+    avoidance of light, 18;
+    prices, 79;
+    sun-spots (_q. v._), 129.
+
+  Herschel’s Outlines, 11.
+
+  Holden, Professor, 124.
+
+  Honeycomb Structure, 30.
+
+  Huggins’s Experiment, 234, 235.
+
+  Humanity, deified, 172.
+
+  Human Race, 250.
+
+  Humboldt, 195.
+
+  Humming-bird, 70.
+
+  Hunt, Professor, 136, 219.
+
+  Hydrogen, 68, 99, 237.
+
+
+  Ibrahim, King, story, 194, 195.
+
+  Ice:
+    melted, 95, 96;
+    never melted, 163, 164.
+
+  Imbrian Sea, 151.
+
+  Insects, 224, 250.
+    (See _Ants_, _Bees_.)
+
+  Iron:
+    melting, 19, 107;
+    appearance of cold, 25;
+    in sun, 28;
+    in man, 221;
+    in stars, 236, 237.
+    (See _Steel_.)
+
+  Ironstone, 188.
+
+  Ivy, 115.
+
+
+  Janssen’s Observations, 61.
+
+  Jevons, Professor, 80.
+
+  Joseph in Egypt, 90.
+
+  Jumping, 241, 242.
+
+  Jupiter, 79, 118, 124, 127–129, 156, 185, 229.
+
+
+  Kensington Museum, 221.
+
+  Kepler, on Comets, 219.
+
+  Kernels, 220.
+
+  Kew, 88.
+
+  Kirchoff’s Researches, 12.
+
+  Krakatao, 181, 185, 186.
+
+
+  La Harpe, quoted, 207.
+
+  Landscape, 169.
+
+  Langley, Prof. S. P.:
+    drawings, 15, 16, 18, 19, 21, 22, 25, 28, 30;
+    note-book, 24;
+    expedition, 180;
+    study of Reflection, 216.
+    (See _Allegheny_, _Pittsburg_.)
+
+  Latent Power, 220.
+
+  Laws of Nature, 250, 251.
+
+  Leaf-like Appearances, 23.
+    (See _Willow_.)
+
+  Lenses, 102, 103;
+    Galileo’s, 123.
+
+  Leo, 195, 197.
+
+  Liais’s Drawing, 48, 50.
+
+  Lick Glass, 123.
+
+  Light:
+    development, 13;
+    day and night, 35;
+    white (_q. v._), 48;
+    mental (see _Eye_), 71;
+    from balloon, 179;
+    transmitted, 227.
+    (See _Sun_.)
+
+  Lightning, 75, 76, 242, 244, 245.
+    (See _Electric_.)
+
+  Lily, 73.
+    (See _Flowers_.)
+
+  Limited Express Train, 5.
+
+  Loaf-sugar, experiment, 188.
+
+  Lockyer’s Land, 130.
+
+  Lockyer’s Solar Physics, 59, 61, 236, 238.
+
+  Lombardy, 151.
+
+  London, 111.
+
+  Lost Pleiad (_q. v._), 207.
+
+  Louis XV., 42.
+
+  Louis XVI., 221.
+
+  Lunar Alps (_q. v._), 148, 149.
+    (See _Moon_.)
+
+  Lunar Apennines (_q. v._), 153.
+
+  Lunar Shadows, 36, 37, 39, 56.
+
+  Lyrids, 196, 200.
+
+
+  Macartney’s Lens, 103.
+
+  Maelstrom, 27.
+
+  Magic Lantern, simile, 220.
+
+  Magnesium, 236, 237.
+
+  Magnetic Needle, 81, 82, 84, 85, 87, 89.
+
+  Mammoth Cave, 40.
+
+  Man, chemistry of, 221, 233.
+    (See _Humanity_.)
+
+  Manhattan Island, 111.
+
+  Mare Crisium, 143.
+
+  Mare Serenitatis, 143, 144.
+
+  Mars, 118, 128–132, 148.
+
+  Mason’s Publication, 137.
+
+  Matterhorn, 148, 167.
+
+  Mayflower, 5.
+
+  Meadows, 172.
+
+  Mecca, 175.
+
+  Medusa, 228.
+
+  Memnon, 234.
+
+  Mercator, 163, 165.
+
+  Mercury, 3, 118, 136, 229.
+
+  Messier, anecdote, 207.
+
+  Metals, melted, 103.
+    (See _Iron_.)
+
+  Metaphysics, 70, 71.
+
+  Meteorites:
+    around Saturn, 124;
+    recent, 187;
+    lawsuit, 187, 188;
+    analyzed, 191, 192;
+    in Iowa, 199, 200;
+    swarm, 200;
+    cracking, 211.
+
+  Meteors, 98, 175–198;
+    (1868), 189.
+    (See _Falling_, _Shooting_.)
+
+  Meunier’s Investigations, 192.
+
+  Mexican Gulf, 38.
+
+  Microcosm, 222.
+
+  Micromegas, 223.
+
+  Microscope, 224.
+
+  Middle Ages, 91, 175.
+
+  Milky Way, 224, 225.
+
+  Milton, quoted, 14, 38.
+
+  Mind-causation, 70, 71.
+
+  Mirror, 102, 107.
+
+  Mississippi, 134.
+
+  Mites, 224.
+
+  Mizar, 207.
+
+  M’Leod’s Drawing, 44.
+
+  Monochromatic Light (_q. v._), 63.
+
+  Montaigne of Limoges, 207.
+
+  Mont Blanc, 156.
+
+  Monte Rosa, 167.
+
+  Moon:
+    practical observations, 2;
+    newly studied, 3;
+    distance, 4–6;
+    size, 5, 6, 140, 156;
+    shadows (_q. v._), 36, 125;
+    in sun-eclipse, 41;
+    planetary relations, 117–174;
+    and Jupiter, 127;
+    photograph, 137;
+    full, 141, 144, 147;
+    Man in the, 143;
+    mountains, 144;
+    craters, 147, 148;
+    temperature, 159;
+    airless, 160;
+    landscape (_q. v._), 169;
+    age, 171;
+    broken up, 192;
+    like comet, 215.
+    (See _Lunar_.)
+
+  Moslem Traditions, 175, 194.
+    (See _Arab_.)
+
+  Moss, 160.
+
+  Mouchot’s Engravings, 109, 112.
+
+  Mountain Sickness, 50, 53.
+
+
+  Naples, 155, 157.
+    (See _Vesuvius_.)
+
+  Napoleon, 80, 134.
+
+  Nasmyth’s Researches, 11, 12, 14, 24, 25, 140.
+
+  Nativity of Jesus, 229.
+
+  Nature’s Laws (_q. v._), 176.
+
+  Nebulæ, 247.
+
+  Needle, 228.
+    (See _Cambric_.)
+
+  Neptune, 121.
+
+  Nerves, none in camera, 47.
+
+  Nerve Transmission, 5, 6.
+
+  New Astronomy, 4, 75, 76, 117, 121, 171, 193, 222, 224, 227, 235,
+          246, 248.
+    (See _Old_.)
+
+  Newcomb, Professor, 55.
+
+  Newspapers, printed by the sun, 74.
+
+  Newton, Professor, 191, 195–197.
+
+  Newton, Sir Isaac, 136, 203, 211;
+    on Comets, 215, 219.
+
+  Nightmare, 67.
+
+  Northern Crown, 208, 211, 230.
+
+  Novelists, theme for, 193, 228.
+
+  Nucleus, 11, 19, 216.
+    (See _Comets_, _Corona_.)
+
+
+  Oceans, 179.
+
+  Old Astronomy, 199, 203, 233.
+    (See _New_.)
+
+  Organisms in sun (_q. v._), 13.
+
+  Orion, 238, 239, 247.
+
+  Oxygen, 73.
+
+
+  Pacific Ocean, 180.
+
+  Palinurus, 243.
+
+  Parable, 224.
+
+  Paris:
+    Observatory, 42, 233, 247;
+    Exposition, 112.
+
+  Parker’s Lens, 103.
+
+  Peirce, Professor, 44.
+
+  Pennsylvania Coal, 97.
+
+  Penumbra, 11, 19, 20.
+
+  Perpignan, France, 42.
+
+  Perseus, 196.
+
+  Persian Rugs, 70.
+
+  Philadelphia, 88.
+
+  Philosopher’s Stone, 92.
+
+  Phœbus, 34.
+
+  Phosphorus, 221.
+
+  Photographic Plate, 71.
+
+  Photography, 9, 19, 128, 236, 237, 241, 244, 247, 248;
+    rapid, 242.
+
+  Photometer, 56, 108.
+
+  Photometry, 230.
+
+  Photosphere, 7, 17, 64.
+
+  Pickering, Professor, 132, 227, 228, 246.
+
+  Pico Summit, 148.
+
+  Piffard, Dr. H. G., 245.
+
+  Pike’s Peak, 50, 53–57, 60.
+
+  Pilgrim Fathers, 5.
+
+  Pine-boughs, 25.
+
+  Pine-trees, 60, 72.
+
+  Pittsburg Observations, 18, 19.
+    (See _Allegheny_, _Langley_.)
+
+  Planetoids, 196, 197, 229.
+
+  Planets:
+    condition, 97;
+    pulverized, 100;
+    and moon, 117–174;
+    isolated, 176.
+    (See _Jupiter_, _Mars_, _Mercury_, _Saturn_, _Sirius_, _Stars_.)
+
+  Plants, 72, 73.
+    (See _Flowers_.)
+
+  Plato Crater, 147, 148, 151, 152.
+
+  Pleiades, 17, 231, 245.
+    (See _Lost_.)
+
+  Plume, The, 19, 23, 24, 55.
+
+  Pointers, 208.
+    (See _Dipper_.)
+
+  Poison, 222.
+
+  Polariscope, 49.
+
+  Polarization, 18.
+
+  Polarizing Eye-piece, 14, 18.
+
+  Polar Star, 230.
+    (See _Great Bear_.)
+
+  Polyp, 152.
+
+  Pores, 24.
+
+  Pouillet’s Invention, 93.
+
+  Printing, indebtedness to the sun, 74.
+
+  Prism, 63, 64.
+    (See _Colors_, _Scarlet_.)
+
+  Proctor’s Observations, 14, 59, 69, 87.
+
+  Prospero’s Wand, 221.
+
+  Ptolemy, 155, 161.
+
+  Pyramids, 99, 117, 233, 234.
+    (See _Egypt_.)
+
+  Pyrheliometer, 93.
+
+
+  Race, simile, 179.
+
+  Radiant Energy, 71, 74;
+    rate, 104.
+
+  Radiation, 101, 108.
+
+  Railway Explosion, 182, 183.
+
+  Railway, The, 156.
+
+  Rain, 111.
+
+  Rainbow, 70.
+
+  Ranyard’s Photographs, 50.
+
+  Red Sea, 116.
+
+  Reflection, 216.
+
+  Repulsive Force, 215.
+
+  Ribbons, 70, 236.
+
+  Rifts, 163, 164.
+
+  Rings, 123, 124, 152, 155.
+    (See _Saturn_.)
+
+  Rockets, 67, 68.
+
+  Rocky Mountains, 88, 89, 180.
+
+  Roman Boy, 34.
+
+  Rope, 20, 26.
+
+  Rose-leaf, 63, 70.
+    (See _Leaves_.)
+
+  Rowland’s Photographs, 237.
+
+  Ruskin, quoted, 29.
+
+  Russia, 134.
+
+  Rutherfurd Photographs, 8, 9, 137, 143, 155, 234.
+
+
+  Sal-ammoniac, 14, 25.
+
+  Salisbury Plain, 1, 2.
+
+  Sandstone, 192.
+
+  Saturn, 118, 119, 121, 123, 124, 127–129, 136, 215.
+
+  Saturnian Dwarfs, 223, 224.
+
+  Saul, comparison, 77.
+
+  Saxon Forefathers, 1, 2.
+    (See _Britain_.)
+
+  Scarlet, 67.
+    (See _Colors_.)
+
+  Schwabe, Hofrath, 76, 77, 87.
+
+  Scott, Sir Walter, quoted, 92.
+
+  Screen, 10, 35–37.
+
+  Seas, lunar (_q. v._), 143.
+
+  Secchi, Father, 14, 15, 24, 25, 29, 30, 43, 59, 235.
+
+  Segmentations, 30, 31.
+
+  Self-luminosity, 215.
+
+  Sextant, 224.
+
+  Shadows. (See _Lunar_.)
+
+  Shakspeare, quoted, 60, 220.
+
+  Sheaves, 68.
+
+  Shelbyville, 42, 43.
+
+  Sherman, observations at, 88.
+
+  Ship, comparison, 133.
+    (See _Steamer_.)
+
+  Shooting-stars, 35, 193, 196, 198, 199.
+    (See _Falling_, _Meteors_.)
+
+  Sicily, 50.
+    (See _Etna_.)
+
+  Siemens, Sir William, 111.
+
+  Sierra Nevada, 151, 160, 180.
+
+  Signal Service, 90.
+
+  Silicon, 107.
+
+  Sirius, 179, 222–224, 236–238.
+
+  Slits, 59, 63, 64.
+
+  Smoked Glass, 11.
+
+  Snow-flakes, 19, 35.
+
+  Snow-like Forms, 25.
+
+  Sodium, 237.
+
+  Solar Engine, 75, 109.
+
+  Solar Light (_q. v._), 13.
+
+  Solar Physics, 4, 12, 14.
+    (See _Sun_.)
+
+  Solar System, 228, 229.
+
+  South America (_q. v._), 80.
+
+  South Carolina, meteors, 194, 195.
+    (See _Charleston_.)
+
+  Southern Cross, 234.
+
+  Space, 181, 211, 224, 227, 229.
+
+  Spain, expedition, 44.
+
+  Sparks, 107, 108.
+
+  Spectra, 231, 237.
+
+  Spectres, 54, 55.
+    (See _Brocken_.)
+
+  Spectroscope, 7, 50, 59, 61, 63, 64, 130, 176, 198, 219, 222,
+          233–235, 240.
+
+  Spectrum, 65, 235.
+
+  Spectrum Analysis, 12.
+
+  Speculations, 193.
+
+  Spinning-wheel, 115.
+
+  Springfield Observations, 44.
+
+  Spurs, 208, 212, 215.
+
+  Star of Bethlehem, 229.
+    (See _Tycho_.)
+
+  Stars:
+    new study, 3;
+    location, 4;
+    size, 4, 230;
+    seen in darkness, 35;
+    self-shining suns, 35, 118;
+    host, 117;
+    variety, 118;
+    five, 118;
+    elements, atmosphere, 179;
+    showers (see _Meteors_), 195;
+    seen through comet, 212, 215;
+    chapter, 221–250;
+    analysis, children, 222;
+    distances, 223;
+    intervals, 224, 227, 229;
+    colors (_q. v._), glory, 227;
+    new, fading, 230;
+    double, 233;
+    relation to man (_q. v._), 233;
+    fixed, 233;
+    changing place, 234;
+    mass, 237;
+    ages, 238;
+    photographed, 244, 247;
+    chart, 247;
+    death, 248.
+    (See _Falling_, _Planets_, _Shooting_.)
+
+  Steam, 74, 75.
+
+  Steamers, 21, 73, 115.
+
+  Steel, melted, 104–108.
+    (See _Iron_.)
+
+  Stellar Spectra (_q. v._), 222, 236, 237, 244, 245.
+
+  Stevenson, George, 111.
+
+  Stewart’s Observations, 88.
+
+  Stonehenge, 1–3.
+
+  Stones:
+    from heaven, 175, 176, 186, 187, 191, 193;
+    Iowa, 199, 200.
+    (See _Meteorites_.)
+
+  Stonyhurst Records, 88.
+
+  Sumbawa Observations, 181.
+
+  Sunbeams:
+    lifting power, 72;
+    Laputa, 73;
+    printing, 74;
+    motes, 215.
+    (See _Light_.)
+
+  Sun:
+    practical observations in Washington, 2, 3;
+    new study, 3;
+    surroundings, 4, 35–69;
+    distance, 4–6;
+    size, 5, 6;
+    a private, 6;
+    views, 6–12, 15, 16, 20;
+    details, 7;
+    fire, 8, 91, 92;
+    telescopic view, 8;
+    axis, 9;
+    revolutions, 10;
+    surface, 17;
+    paper record, 18;
+    heat (_q. v._) and eye, 19;
+    drawings exaggerated, 29, 30;
+    something brighter, 32;
+    atmosphere, 33, 34;
+    slits, 59;
+    miniature, 64;
+    flames (_q. v._), 69;
+    energy, 70–116 (see _Heat_);
+    versatile aid, 74;
+    children, 75, 222;
+    shrinkage, 99;
+    ground up, 100;
+    emissive power, 104;
+    constitution and appearance, 111;
+    god, 116;
+    self-shining, 118;
+    studied from mountains, 167;
+    affected by dust (_q. v._), 185;
+    and comet, 216;
+    elements, 233;
+    a star, 237;
+    life, 238;
+    candle, 249;
+    anecdote, 250.
+    (See _Solar_.)
+
+  Sunrise, 234.
+
+  Sunset, 181, 182.
+    (See _Twilight_.)
+
+  Suns:
+    millions, 224;
+    dwindling, 227;
+    periods, 241.
+
+  Sun-spots, 1–34 _passim_;
+    ancient, 8;
+    early observations, 8;
+    changing, 9;
+    great, 10, 20, 24;
+    individuality, darker, 11;
+    leaves (_q. v._), 11, 12;
+    how observed, 18, 19;
+    typical, 21, 22;
+    relative size, 20;
+    hook-shaped (see _Plume_), 24;
+    signs of chaos, 27;
+    double, 32;
+    weather, 76, 90;
+    periodicity, 76–78;
+    temperature, 83;
+    records, 85;
+    variations, 87;
+    (1870), 9, 15, 16, 20;
+    (1873), 20–24;
+    (1875), 25, 28, 30;
+    (1876), 30, 32;
+    (1882), 80, 83–86, 90.
+
+  Superga, 38.
+
+  Swift, Dean, 73, 131, 132.
+    (See _Gulliver_.)
+
+  Sword Meteor (_q. v._), 175.
+
+
+  Tacchini’s Investigations, 43, 49, 62, 66, 68.
+
+  Tail, 215, 216.
+    (See _Comets_.)
+
+  Tan, 71.
+
+  Taylor, Bayard, 139.
+
+  Telephone, 84, 89.
+
+  Telescopes:
+    many, 17;
+    best, 134;
+    alone, 227, 230;
+    use, 233, 234.
+
+  Temperature, 101, 102, 108;
+    of space, 224, 227.
+
+  Terminator, 147.
+
+  Thermometer, 71, 93, 102;
+    low, 160, 163.
+
+  Time, small divisions, 241.
+
+  Tippoo Saib, 221.
+
+  Total Eclipse (_q. v._), 39–48 _passim_, 55, 59.
+
+  Trees, lacking, 168.
+
+  Tribune, The New York, 84.
+
+  Trinity Church, 72.
+
+  Trocadéro, 112.
+
+  Trouvelot, E. L., 119, 123, 225.
+
+  Turin, 38.
+
+  Twilight, small, 38.
+
+  Tycho, 144, 229.
+    (See _Star_.)
+
+  Tyndall, 98.
+
+
+  Umbra, 11, 12, 19, 20.
+
+  United States, comparison, 24.
+
+  Uranus, 3, 196.
+
+  Vapor, 28.
+
+  Vega, 235, 246.
+
+  Vegetables, 74.
+
+  Veils, 14, 17.
+
+  Venus, 118.
+
+  Vernier, 3.
+
+  Vesuvius:
+    crater, 155, 157;
+    eruption, 181, 183.
+    (See _Naples_.)
+
+  Vibrations, 72.
+
+  Victoria, 115.
+
+  Viscous Fluid, 26.
+
+  Vital Force, 14.
+
+  Vogel, H. C., 64, 66.
+
+  Voids, 181, 227.
+
+  Volcanoes, 27, 28;
+    in moon, 167, 193.
+
+
+  Wandering Star, 101.
+    (See _Comets_, _Falling_.)
+
+  Washington:
+    Observatory, 2, 86–88;
+    telescope, 122;
+    Monument, 182.
+
+  Water, 152;
+    in man, 221.
+
+  Waterloo, 80.
+
+  Water-wheel, 111.
+
+  Watson’s Observations, 49.
+
+  Wheat, prices, 79.
+    (See _Breadstuffs_, _Corn_, _Grain_, _Sun-spots_.)
+
+  Wheel, comparison, 10.
+
+  Whirlpools, 28, 31.
+
+  Whirlwinds, 23, 31.
+
+  White Light (_q. v._), 48, 62, 63.
+
+  Whitney, Mount, 177.
+
+  Willow-leaves (_q. v._), 11, 12, 14.
+
+  Wing, simile, 215.
+
+  Winlock, Professor, 44.
+
+  Withered Surfaces, 168, 171.
+
+  Wood-engraving, 50.
+
+  Worlds and Clouds, 249.
+
+  Wrinkles, 172.
+
+
+  Xeres, Spain (_q. v._), 44, 53.
+
+
+  Young, Professor:
+    spectroscope, 44, 50, 65, 234;
+    observations, 56, 59, 61, 68, 69;
+    magnetism, 87, 88;
+    radiation, 101.
+
+
+  Zodiacal Light, 55.
+
+
+University Press: John Wilson & Son, Cambridge.
+
+
+
+
+Transcriber’s Notes
+
+
+Punctuation, hyphenation, and spelling were made consistent when a
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+        text-indent: -1em;
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+    }
+
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+<body>
+
+<div style='text-align:center; font-size:1.2em; font-weight:bold'>The Project Gutenberg eBook of The New Astronomy, by Samuel Pierpont Langley</div>
+
+<div style='display:block; margin:1em 0'>
+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 <a href="https://www.gutenberg.org">www.gutenberg.org</a>. If you
+are not located in the United States, you will have to check the laws of the
+country where you are located before using this eBook.
+</div>
+
+<div style='display:block; margin-top:1em; margin-bottom:1em; margin-left:2em; text-indent:-2em'>Title: The New Astronomy</div>
+
+<div style='display:block; margin-top:1em; margin-bottom:1em; margin-left:2em; text-indent:-2em'>Author: Samuel Pierpont Langley</div>
+
+<div style='display:block; margin:1em 0'>Release Date: February 16, 2021 [eBook #64577]</div>
+
+<div style='display:block; margin:1em 0'>Language: English</div>
+
+<div style='display:block; margin:1em 0'>Character set encoding: UTF-8</div>
+
+<div style='display:block; margin-left:2em; text-indent:-2em'>Produced by: Tim Lindell, Charlie Howard, and the Online Distributed Proofreading Team at https://www.pgdp.net (This file was produced from images generously made available by The Internet Archive/American Libraries.)</div>
+
+<div style='margin-top:2em; margin-bottom:4em'>*** START OF THE PROJECT GUTENBERG EBOOK THE NEW ASTRONOMY ***</div>
+
+<div class="transnote">
+<p class="larger center">Transcriber’s Note</p>
+
+<p class="covernote">Cover created by Transcriber, using an image
+from the original book, and placed in the
+Public Domain.</p>
+
+<p>Larger versions of most illustrations may be seen by right-clicking them
+and selecting an option to view them separately, or by double-tapping and/or
+stretching them.</p>
+</div>
+
+<h1 class="wspace">THE NEW ASTRONOMY</h1>
+
+<hr />
+
+<div class="newpage p4 center vspace wspace larger">
+<p class="xxlarge">THE NEW ASTRONOMY</p>
+
+<p class="p4 xsmall">BY</p>
+
+<p class="p2">SAMUEL PIERPONT LANGLEY, <span class="smcap">Ph.D.</span>, LL.D.</p>
+
+<p class="xxsmall">DIRECTOR OF THE ALLEGHENY OBSERVATORY, MEMBER NATIONAL ACADEMY,<br />
+FELLOW ROYAL ASTRONOMICAL SOCIETY, ETC., ETC.</p>
+
+<p class="p2 bold">Illustrated</p>
+
+<div id="if_i_002" class="figcenter" style="max-width: 7em;">
+  <img src="images/i_002.png" alt="" /></div>
+
+<p class="p2"><span class="gesperrt">BOSTON.<br />
+<span class="smaller">TICKNOR AND COMPANY</span></span><br />
+<span class="small">211 Tremont Street</span><br />
+<span class="smaller">1888</span>
+</p>
+</div>
+
+<hr />
+
+<div class="newpage p4 center smaller">
+<p>
+<span class="smcap">Copyright, 1884, 1885, 1886, and 1887, by the Century Co.;<br />
+and 1887, by S. P. Langley.</span></p>
+
+<p class="p1"><i>All rights reserved.</i></p>
+
+<p class="p4"><span class="bold">University Press</span>:<br />
+<span class="smcap">John Wilson and Son, Cambridge.</span>
+</p>
+</div>
+
+<hr />
+
+<div class="chapter">
+<h2 class="nobreak" id="PREFACE">PREFACE.</h2>
+</div>
+
+<p class="drop-cap i"><span class="smcap1">I have</span> written these pages, not for the professional reader,
+but with the hope of reaching a part of that educated
+public on whose support he is so often dependent for the
+means of extending the boundaries of knowledge.</p>
+
+<p>It is not generally understood that among us not only the
+support of the Government, but with scarcely an exception
+every new private benefaction, is devoted to “the Old” Astronomy,
+which is relatively munificently endowed already;
+while that which I have here called “the New,” so fruitful in
+results of interest and importance, struggles almost unaided.</p>
+
+<p>We are all glad to know that Urania, who was in the beginning
+but a poor Chaldean shepherdess, has long since become
+well-to-do, and dwells now in state. It is far less known than
+it should be that she has a younger sister now among us,
+bearing every mark of her celestial birth, but all unendowed
+and portionless. It is for the reader’s interest in the latter
+that this book is a plea.</p>
+
+<hr />
+
+<div class="chapter">
+<h2 class="nobreak" id="CONTENTS">CONTENTS.</h2>
+</div>
+
+<table id="toc" summary="Contents">
+<tr class="smaller">
+  <td class="tdl" colspan="2"><span class="smcap"><span class="in1">Chapter</span></span></td>
+  <td class="tdr"><span class="smcap">Page</span></td>
+</tr>
+<tr>
+  <td class="tdr top">I.</td>
+  <td class="tdl"><span class="smcap">Spots on the Sun</span></td>
+  <td class="tdr"><a href="#toclink_1">1</a></td>
+</tr>
+<tr>
+  <td class="tdr top">II.</td>
+  <td class="tdl"><span class="smcap">The Sun’s Surroundings</span></td>
+  <td class="tdr"><a href="#toclink_35">35</a></td>
+</tr>
+<tr>
+  <td class="tdr top">III.</td>
+  <td class="tdl"><span class="smcap">The Sun’s Energy</span></td>
+  <td class="tdr"><a href="#toclink_70">70</a></td>
+</tr>
+<tr>
+  <td class="tdr top">IV.</td>
+  <td class="tdl"><span class="smcap">The Sun’s Energy</span> (<i>Continued</i>)</td>
+  <td class="tdr"><a href="#toclink_91">91</a></td>
+</tr>
+<tr>
+  <td class="tdr top">V.</td>
+  <td class="tdl"><span class="smcap">The Planets and the Moon</span></td>
+  <td class="tdr"><a href="#toclink_117">117</a></td>
+</tr>
+<tr>
+  <td class="tdr top">VI.</td>
+  <td class="tdl"><span class="smcap">Meteors</span></td>
+  <td class="tdr"><a href="#toclink_175">175</a></td>
+</tr>
+<tr>
+  <td class="tdr top">VII.</td>
+  <td class="tdl"><span class="smcap">Comets</span></td>
+  <td class="tdr"><a href="#toclink_199">199</a></td>
+</tr>
+<tr>
+  <td class="tdr top">VIII.</td>
+  <td class="tdl"><span class="smcap">The Stars</span></td>
+  <td class="tdr"><a href="#toclink_221">221</a></td>
+</tr>
+<tr>
+  <td class="tdl" colspan="2"><span class="in1">INDEX</span></td>
+  <td class="tdr"><a href="#INDEX">253</a></td>
+</tr>
+</table>
+
+<hr />
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_ix">ix</span></p>
+
+<h2 class="nobreak" id="LIST_OF_ILLUSTRATIONS">LIST OF ILLUSTRATIONS.</h2>
+</div>
+
+<table id="loi" summary="List of Illustrations">
+<tr class="smaller">
+  <td class="tdl" colspan="2"><span class="smcap">Figure</span></td>
+  <td class="tdr"><span class="smcap">Page</span></td>
+</tr>
+<tr>
+  <td class="tdr top">1.</td>
+  <td class="tdl"><span class="smcap">The Sun’s Surroundings</span></td>
+  <td class="tdr"><a href="#ip_1">4</a></td>
+</tr>
+<tr>
+  <td class="tdr top">2.</td>
+  <td class="tdl"><span class="smcap">View of the Sun on Sept. 20, 1870</span></td>
+  <td class="tdr"><a href="#ip_2">6</a></td>
+</tr>
+<tr>
+  <td class="tdr top">3.</td>
+  <td class="tdl"><span class="smcap">The Sun on Sept. 22, 1870</span></td>
+  <td class="tdr"><a href="#ip_3">6</a></td>
+</tr>
+<tr>
+  <td class="tdr top">4.</td>
+  <td class="tdl"><span class="smcap">The Sun on Sept. 26, 1870</span></td>
+  <td class="tdr"><a href="#ip_4">7</a></td>
+</tr>
+<tr>
+  <td class="tdr top">5.</td>
+  <td class="tdl"><span class="smcap">The Sun on Sept. 19, 1870</span></td>
+  <td class="tdr"><a href="#ip_5">8</a></td>
+</tr>
+<tr>
+  <td class="tdr top">6.</td>
+  <td class="tdl"><span class="smcap">The Sun on Sept. 20, 1870</span></td>
+  <td class="tdr"><a href="#ip_6">8</a></td>
+</tr>
+<tr>
+  <td class="tdr top">7.</td>
+  <td class="tdl"><span class="smcap">The Sun on Sept. 21, 1870</span></td>
+  <td class="tdr"><a href="#ip_7">9</a></td>
+</tr>
+<tr>
+  <td class="tdr top">8.</td>
+  <td class="tdl"><span class="smcap">The Sun on Sept. 22, 1870</span></td>
+  <td class="tdr"><a href="#ip_8">9</a></td>
+</tr>
+<tr>
+  <td class="tdr top">9.</td>
+  <td class="tdl"><span class="smcap">The Sun on Sept. 23, 1870</span></td>
+  <td class="tdr"><a href="#ip_9">10</a></td>
+</tr>
+<tr>
+  <td class="tdr top">10.</td>
+  <td class="tdl"><span class="smcap">The Sun on Sept. 26, 1870</span></td>
+  <td class="tdr"><a href="#ip_10">10</a></td>
+</tr>
+<tr>
+  <td class="tdr top">11.</td>
+  <td class="tdl"><span class="smcap">Nasmyth’s Willow Leaves</span></td>
+  <td class="tdr"><a href="#ip_11">11</a></td>
+</tr>
+<tr>
+  <td class="tdr top">12.</td>
+  <td class="tdl"><span class="smcap">The Cactus Type</span></td>
+  <td class="tdr"><a href="#ip_12">12</a></td>
+</tr>
+<tr>
+  <td class="tdr top">13.</td>
+  <td class="tdl"><span class="smcap">Equatorial Telescope and Projection</span></td>
+  <td class="tdr"><a href="#ip_13">13</a></td>
+</tr>
+<tr>
+  <td class="tdr top">14.</td>
+  <td class="tdl"><span class="smcap">Polarizing Eye-piece</span></td>
+  <td class="tdr"><a href="#ip_14">14</a></td>
+</tr>
+<tr>
+  <td class="tdr top">15.</td>
+  <td class="tdl"><span class="smcap">Spot of Sept. 21, 1870</span></td>
+  <td class="tdr"><a href="#ip_15">15</a></td>
+</tr>
+<tr>
+  <td class="tdr top">16.</td>
+  <td class="tdl"><span class="smcap">Spot of March 5, 1873</span></td>
+  <td class="tdr"><a href="#ip_16">15</a></td>
+</tr>
+<tr>
+  <td class="tdr top">17.</td>
+  <td class="tdl"><span class="smcap">Sun on March 5, 1873</span></td>
+  <td class="tdr"><a href="#ip_17">18</a></td>
+</tr>
+<tr>
+  <td class="tdr top">18.</td>
+  <td class="tdl"><span class="smcap">“The Plume” Spot of March 5 and 6, 1873</span></td>
+  <td class="tdr"><a href="#ip_18">19</a></td>
+</tr>
+<tr>
+  <td class="tdr top">19.</td>
+  <td class="tdl"><span class="smcap">Typical Sun-spot of December, 1873</span></td>
+  <td class="tdr"><a href="#ip_19">21</a></td>
+</tr>
+<tr>
+  <td class="tdr top">20.</td>
+  <td class="tdl"><span class="smcap">Frost Crystal</span></td>
+  <td class="tdr"><a href="#ip_20">23</a></td>
+</tr>
+<tr>
+  <td class="tdr top">21.</td>
+  <td class="tdl"><span class="smcap">Cyclone Spot</span></td>
+  <td class="tdr"><a href="#ip_21">24</a></td>
+</tr>
+<tr>
+  <td class="tdr top">22.</td>
+  <td class="tdl"><span class="smcap">Spot of March 31, 1875</span></td>
+  <td class="tdr"><a href="#ip_22">25</a></td>
+</tr>
+<tr>
+  <td class="tdr top">23.</td>
+  <td class="tdl"><span class="smcap">Cirrous Cloud</span></td>
+  <td class="tdr"><a href="#ip_23">27</a><span class="pagenum" id="Page_x">x</span></td>
+</tr>
+<tr>
+  <td class="tdr top">24.</td>
+  <td class="tdl"><span class="smcap">Spot of March 31, 1875</span></td>
+  <td class="tdr"><a href="#ip_24">28</a></td>
+</tr>
+<tr>
+  <td class="tdr top">25.</td>
+  <td class="tdl"><span class="smcap">Typical Illustration of Faye’s Theory</span></td>
+  <td class="tdr"><a href="#ip_25">29</a></td>
+</tr>
+<tr>
+  <td class="tdr top">26.</td>
+  <td class="tdl"><span class="smcap">Spot of Oct. 13, 1876</span></td>
+  <td class="tdr"><a href="#ip_26">30</a></td>
+</tr>
+<tr>
+  <td class="tdr top">27.</td>
+  <td class="tdl"><span class="smcap">Photograph of Edge of Sun</span></td>
+  <td class="tdr"><a href="#ip_27">31</a></td>
+</tr>
+<tr>
+  <td class="tdr top">28.</td>
+  <td class="tdl"><span class="smcap">Facula</span></td>
+  <td class="tdr"><a href="#ip_28">33</a></td>
+</tr>
+<tr>
+  <td class="tdr top">29.</td>
+  <td class="tdl"><span class="smcap">Lunar Cone Shadow</span></td>
+  <td class="tdr"><a href="#ip_29">36</a></td>
+</tr>
+<tr>
+  <td class="tdr top">30.</td>
+  <td class="tdl"><span class="smcap">Track of Lunar Shadow</span></td>
+  <td class="tdr"><a href="#ip_30">39</a></td>
+</tr>
+<tr>
+  <td class="tdr top">31.</td>
+  <td class="tdl"><span class="smcap">Inner Corona Eclipse of 1869</span></td>
+  <td class="tdr"><a href="#ip_31">40</a></td>
+</tr>
+<tr>
+  <td class="tdr top">32.</td>
+  <td class="tdl"><span class="smcap">Sketch of Outer Corona, 1869</span></td>
+  <td class="tdr"><a href="#ip_32">41</a></td>
+</tr>
+<tr>
+  <td class="tdr top">33.</td>
+  <td class="tdl"><span class="smcap">Tacchini’s Drawing of Corona of 1870</span></td>
+  <td class="tdr"><a href="#ip_33">43</a></td>
+</tr>
+<tr>
+  <td class="tdr top">34.</td>
+  <td class="tdl"><span class="smcap">Watson’s Naked-eye Drawing of Corona of 1870</span></td>
+  <td class="tdr"><a href="#ip_34">44</a></td>
+</tr>
+<tr>
+  <td class="tdr top">35.</td>
+  <td class="tdl"><span class="smcap">Photograph showing Commencement of Outer Corona</span></td>
+  <td class="tdr"><a href="#ip_35">45</a></td>
+</tr>
+<tr>
+  <td class="tdr top">36.</td>
+  <td class="tdl"><span class="smcap">Eclipse of 1857, Drawing by Liais</span></td>
+  <td class="tdr"><a href="#ip_36">48</a></td>
+</tr>
+<tr>
+  <td class="tdr top">37.</td>
+  <td class="tdl"><span class="smcap">Enlargement of Part of <a href="#ip_38">Fig. 38</a></span></td>
+  <td class="tdr"><a href="#ip_37">49</a></td>
+</tr>
+<tr>
+  <td class="tdr top">38.</td>
+  <td class="tdl"><span class="smcap">Fac-simile of Photograph of Corona of 1871</span></td>
+  <td class="tdr"><a href="#ip_38">51</a></td>
+</tr>
+<tr>
+  <td class="tdr top">39.</td>
+  <td class="tdl">“<span class="smcap">Spectres</span>”</td>
+  <td class="tdr"><a href="#ip_39">54</a></td>
+</tr>
+<tr>
+  <td class="tdr top">40.</td>
+  <td class="tdl"><span class="smcap">Outer Corona of 1878</span></td>
+  <td class="tdr"><a href="#ip_40">57</a></td>
+</tr>
+<tr>
+  <td class="tdr top">41.</td>
+  <td class="tdl"><span class="smcap">Spectroscope Slit and Solar Image</span></td>
+  <td class="tdr"><a href="#ip_41">59</a></td>
+</tr>
+<tr>
+  <td class="tdr top">42.</td>
+  <td class="tdl"><span class="smcap">Slit and Prominences</span></td>
+  <td class="tdr"><a href="#ip_42">59</a></td>
+</tr>
+<tr>
+  <td class="tdr top">43.</td>
+  <td class="tdl"><span class="smcap">Tacchini’s Chromospheric Clouds</span></td>
+  <td class="tdr"><a href="#ip_43">62</a></td>
+</tr>
+<tr>
+  <td class="tdr top">44.</td>
+  <td class="tdl"><span class="smcap">Tacchini’s Chromospheric Clouds</span></td>
+  <td class="tdr"><a href="#ip_44">62</a></td>
+</tr>
+<tr>
+  <td class="tdr top">45.</td>
+  <td class="tdl"><span class="smcap">Vogel’s Chromospheric Forms</span></td>
+  <td class="tdr"><a href="#ip_45">64</a></td>
+</tr>
+<tr>
+  <td class="tdr top">46.</td>
+  <td class="tdl"><span class="smcap">Tacchini’s Chromospheric Forms</span></td>
+  <td class="tdr"><a href="#ip_46">66</a></td>
+</tr>
+<tr>
+  <td class="tdr top">47.</td>
+  <td class="tdl"><span class="smcap">Eruptive Prominences</span></td>
+  <td class="tdr"><a href="#ip_47">67</a></td>
+</tr>
+<tr>
+  <td class="tdr top">48.</td>
+  <td class="tdl"><span class="smcap">Sun-spots and Price of Grain</span></td>
+  <td class="tdr"><a href="#ip_48">77</a></td>
+</tr>
+<tr>
+  <td class="tdr top">49.</td>
+  <td class="tdl"><span class="smcap">Sun-spot of Nov. 16, 1882, and Earth</span></td>
+  <td class="tdr"><a href="#ip_49">80</a></td>
+</tr>
+<tr>
+  <td class="tdr top">50.</td>
+  <td class="tdl"><span class="smcap">Greenwich Record of Disturbance of Magnetic Needle, Nov. 16 and 17, 1882</span></td>
+  <td class="tdr"><a href="#ip_50">81</a></td>
+</tr>
+<tr>
+  <td class="tdr top">51.</td>
+  <td class="tdl"><span class="smcap">Sun-spots and Magnetic Variations</span></td>
+  <td class="tdr"><a href="#ip_51">87</a></td>
+</tr>
+<tr>
+  <td class="tdr top">52.</td>
+  <td class="tdl"><span class="smcap">Greenwich Magnetic Observations, Aug. 3 and 5, 1872</span></td>
+  <td class="tdr"><a href="#ip_52">89</a></td>
+</tr>
+<tr>
+  <td class="tdr top">53.</td>
+  <td class="tdl"><span class="smcap">One Cubic Centimetre</span></td>
+  <td class="tdr"><a href="#ip_53">93</a></td>
+</tr>
+<tr>
+  <td class="tdr top">54.</td>
+  <td class="tdl"><span class="smcap">Pouillet’s Pyrheliometer</span></td>
+  <td class="tdr"><a href="#ip_54">93</a></td>
+</tr>
+<tr>
+  <td class="tdr top">55.</td>
+  <td class="tdl"><span class="smcap">Bernières’s great Burning-Glass</span></td>
+  <td class="tdr"><a href="#ip_55">103</a><span class="pagenum" id="Page_xi">xi</span></td>
+</tr>
+<tr>
+  <td class="tdr top">56.</td>
+  <td class="tdl"><span class="smcap">A “Pour” from the Bessemer Converter</span></td>
+  <td class="tdr"><a href="#ip_56">105</a></td>
+</tr>
+<tr>
+  <td class="tdr top">57.</td>
+  <td class="tdl"><span class="smcap">Photometer-box</span></td>
+  <td class="tdr"><a href="#ip_57">108</a></td>
+</tr>
+<tr>
+  <td class="tdr top">58.</td>
+  <td class="tdl"><span class="smcap">Mouchot’s Solar Engine</span></td>
+  <td class="tdr"><a href="#ip_58">109</a></td>
+</tr>
+<tr>
+  <td class="tdr top">59.</td>
+  <td class="tdl"><span class="smcap">Ericsson’s new Solar Engine, now in Practical Use in New York</span></td>
+  <td class="tdr"><a href="#ip_59">113</a></td>
+</tr>
+<tr>
+  <td class="tdr top">60.</td>
+  <td class="tdl"><span class="smcap">Saturn</span></td>
+  <td class="tdr"><a href="#ip_60">119</a></td>
+</tr>
+<tr>
+  <td class="tdr top">61.</td>
+  <td class="tdl"><span class="smcap">The Equatorial Telescope at Washington</span></td>
+  <td class="tdr"><a href="#ip_61">122</a></td>
+</tr>
+<tr>
+  <td class="tdr top">62.</td>
+  <td class="tdl"><span class="smcap">Jupiter, Moon, and Shadow</span></td>
+  <td class="tdr"><a href="#ip_62">125</a></td>
+</tr>
+<tr>
+  <td class="tdr top">63.</td>
+  <td class="tdl"><span class="smcap">Three Views of Mars</span></td>
+  <td class="tdr"><a href="#ip_63">129</a></td>
+</tr>
+<tr>
+  <td class="tdr top">64.</td>
+  <td class="tdl"><span class="smcap">Map of Mars</span></td>
+  <td class="tdr"><a href="#ip_64">129</a></td>
+</tr>
+<tr>
+  <td class="tdr top">65.</td>
+  <td class="tdl"><span class="smcap">The Moon</span></td>
+  <td class="tdr"><a href="#ip_65">137</a></td>
+</tr>
+<tr>
+  <td class="tdr top">66.</td>
+  <td class="tdl"><span class="smcap">The Full Moon</span></td>
+  <td class="tdr"><a href="#ip_66">141</a></td>
+</tr>
+<tr>
+  <td class="tdr top">67.</td>
+  <td class="tdl"><span class="smcap">Glass Globe, Cracked</span></td>
+  <td class="tdr"><a href="#ip_67">145</a></td>
+</tr>
+<tr>
+  <td class="tdr top">68.</td>
+  <td class="tdl"><span class="smcap">Plato and the Lunar Alps</span></td>
+  <td class="tdr"><a href="#ip_68">149</a></td>
+</tr>
+<tr>
+  <td class="tdr top">69.</td>
+  <td class="tdl"><span class="smcap">The Lunar Apennines: Archimedes</span></td>
+  <td class="tdr"><a href="#ip_69">153</a></td>
+</tr>
+<tr>
+  <td class="tdr top">70.</td>
+  <td class="tdl"><span class="smcap">Vesuvius and Neighborhood of Naples</span></td>
+  <td class="tdr"><a href="#ip_70">157</a></td>
+</tr>
+<tr>
+  <td class="tdr top">71.</td>
+  <td class="tdl"><span class="smcap">Ptolemy and Arzachel</span></td>
+  <td class="tdr"><a href="#ip_71">161</a></td>
+</tr>
+<tr>
+  <td class="tdr top">72.</td>
+  <td class="tdl"><span class="smcap">Mercator and Campanus</span></td>
+  <td class="tdr"><a href="#ip_72">165</a></td>
+</tr>
+<tr>
+  <td class="tdr top">73.</td>
+  <td class="tdl"><span class="smcap">Withered Hand</span></td>
+  <td class="tdr"><a href="#ip_73">168</a></td>
+</tr>
+<tr>
+  <td class="tdr top">74.</td>
+  <td class="tdl"><span class="smcap">Ideal Lunar Landscape and Earth-shine</span></td>
+  <td class="tdr"><a href="#ip_74">169</a></td>
+</tr>
+<tr>
+  <td class="tdr top">75.</td>
+  <td class="tdl"><span class="smcap">Withered Apple</span></td>
+  <td class="tdr"><a href="#ip_75">171</a></td>
+</tr>
+<tr>
+  <td class="tdr top">76.</td>
+  <td class="tdl"><span class="smcap">Gassendi. Nov. 7, 1867</span></td>
+  <td class="tdr"><a href="#ip_76">173</a></td>
+</tr>
+<tr>
+  <td class="tdr top">77.</td>
+  <td class="tdl"><span class="smcap">The Camp at Mount Whitney</span></td>
+  <td class="tdr"><a href="#ip_77">177</a></td>
+</tr>
+<tr>
+  <td class="tdr top">78.</td>
+  <td class="tdl"><span class="smcap">Vesuvius during an Eruption</span></td>
+  <td class="tdr"><a href="#ip_78">183</a></td>
+</tr>
+<tr>
+  <td class="tdr top">79.</td>
+  <td class="tdl"><span class="smcap">Meteors observed Nov. 13 and 14, 1868, between Midnight and Five o’Clock, a. m.</span></td>
+  <td class="tdr"><a href="#ip_79">189</a></td>
+</tr>
+<tr>
+  <td class="tdr top">80.</td>
+  <td class="tdl"><span class="smcap">Comet of Donati, Sept. 16, 1858</span></td>
+  <td class="tdr"><a href="#ip_80">201</a></td>
+</tr>
+<tr>
+  <td class="tdr top">81.</td>
+  <td class="tdl">“<span class="smcap">A Part of a Comet</span>”</td>
+  <td class="tdr"><a href="#ip_81">203</a></td>
+</tr>
+<tr>
+  <td class="tdr top">82.</td>
+  <td class="tdl"><span class="smcap">Comet of Donati, Sept. 24, 1858</span></td>
+  <td class="tdr"><a href="#ip_82">205</a></td>
+</tr>
+<tr>
+  <td class="tdr top">83.</td>
+  <td class="tdl"><span class="smcap">Comet of Donati, Oct. 3, 1858</span></td>
+  <td class="tdr"><a href="#ip_83">209</a></td>
+</tr>
+<tr>
+  <td class="tdr top">84.</td>
+  <td class="tdl"><span class="smcap">Comet of Donati, Oct. 9, 1858</span></td>
+  <td class="tdr"><a href="#ip_84">213</a></td>
+</tr>
+<tr>
+  <td class="tdr top">85.</td>
+  <td class="tdl"><span class="smcap">Comet of Donati, Oct. 5, 1858</span></td>
+  <td class="tdr"><a href="#ip_85">217</a></td>
+</tr>
+<tr>
+  <td class="tdr top">86.</td>
+  <td class="tdl"><span class="smcap">Types of Stellar Spectra</span></td>
+  <td class="tdr"><a href="#ip_86">222</a><span class="pagenum" id="Page_xii">xii</span></td>
+</tr>
+<tr>
+  <td class="tdr top">87.</td>
+  <td class="tdl"><span class="smcap">The Milky Way</span></td>
+  <td class="tdr"><a href="#ip_87">225</a></td>
+</tr>
+<tr>
+  <td class="tdr top">88.</td>
+  <td class="tdl"><span class="smcap">Spectra of Stars in Pleiades</span></td>
+  <td class="tdr"><a href="#ip_88">231</a></td>
+</tr>
+<tr>
+  <td class="tdr top">89.</td>
+  <td class="tdl"><span class="smcap">Spectrum of Aldebaran</span></td>
+  <td class="tdr"><a href="#ip_89">235</a></td>
+</tr>
+<tr>
+  <td class="tdr top">90.</td>
+  <td class="tdl"><span class="smcap">Spectrum of Vega</span></td>
+  <td class="tdr"><a href="#ip_90">235</a></td>
+</tr>
+<tr>
+  <td class="tdr top">91.</td>
+  <td class="tdl"><span class="smcap">Great Nebula in Orion</span></td>
+  <td class="tdr"><a href="#ip_91">239</a></td>
+</tr>
+<tr>
+  <td class="tdr top">92.</td>
+  <td class="tdl"><span class="smcap">A Falling Man</span></td>
+  <td class="tdr"><a href="#ip_92">243</a></td>
+</tr>
+<tr>
+  <td class="tdr top">93.</td>
+  <td class="tdl"><span class="smcap">A Flash of Lightning</span></td>
+  <td class="tdr"><a href="#ip_93">245</a></td>
+</tr>
+</table>
+
+<hr />
+
+<div id="toclink_1" class="chapter">
+<p><span class="pagenum" id="Page_1">1</span></p>
+
+<h2 class="nobreak" id="THE_NEW_ASTRONOMY">THE NEW ASTRONOMY.</h2>
+</div>
+
+<hr />
+
+<div class="chapter">
+<h2 class="nobreak" id="I">I.<br />
+
+<span class="subhead">SPOTS ON THE SUN.</span></h2>
+</div>
+
+<p class="drop-cap"><span class="smcap1">The</span> visitor to Salisbury Plain sees around him a lonely
+waste, utterly barren except for a few recently planted
+trees, and otherwise as desolate as it could have been when
+Hengist and Horsa landed in Britain; for its monotony is still
+unbroken except by the funeral mounds of ancient chiefs, which
+dot it to its horizon, and contrast strangely with the crowded life
+and fertile soil which everywhere surround its borders. In the
+midst of this loneliness rise the rude, enormous monoliths of
+Stonehenge,—circles of gray stones, which seem as old as time,
+and were there, as we now are told, the temple of a people which
+had already passed away, and whose worship was forgotten,
+when our Saxon forefathers first saw the place.</p>
+
+<p>In the centre of the inner circle is a stone which is believed
+once to have been the altar; while beyond the outmost ring,
+quite away to the northeast upon the open plain, still stands a
+solitary stone, set up there evidently with some special object
+by the same unknown builders. Seen under ordinary circumstances,
+it is difficult to divine its connection with the others;
+but we are told that once in each year, upon the morning of the
+longest day, the level shadow of this distant, isolated stone is
+projected at sunrise to the very centre of the ancient sanctuary,
+and falls just upon the altar. The primitive man who devised<span class="pagenum" id="Page_2">2</span>
+this was both astronomer and priest, for he not only adored the
+risen god whose first beams brought him light and warmth, but
+he could mark its place, and though utterly ignorant of its nature,
+had evidently learned enough of its motions to embody
+his simple astronomical knowledge in a record so exact and so
+enduring that though his very memory has gone, common men
+are still interested in it; for, as I learned when viewing the
+scene, people are accustomed to come from all the surrounding
+country, and pass in this desolate spot the short night preceding
+the longest day of the year, to see the shadow touch the altar
+at the moment of sunrise.</p>
+
+<p>Most great national observatories, like Greenwich or Washington,
+are the perfected development of that kind of astronomy
+of which the builders of Stonehenge represent the infancy.
+Those primitive men could know where the sun would rise on
+a certain day, and make their observation of its place, as we see,
+very well, without knowing anything of its physical nature. At
+Greenwich the moon has been observed with scarcely an intermission
+for one hundred and fifty years, but we should mistake
+greatly did we suppose that it was for the purpose of seeing
+what it was made of, or of making discoveries in it. This immense
+mass of Greenwich observations is for quite another purpose,—for
+the very practical purpose of forming the lunar
+tables, which, by means of the moon’s place among the stars,
+will tell the navigator in distant oceans where he is, and conduct
+the fleets of England safely home.</p>
+
+<p>In the observatory at Washington one may see a wonderfully
+exact instrument, in which circles of brass have replaced circles
+of stone, all so bolted between massive piers that the sun can be
+observed by it but once daily, as it crosses the meridian. This
+instrument is the completed attainment along that long line of
+progress in one direction, of which the solitary stone at Stonehenge
+marks the initial step,—the attainment, that is, purely of<span class="pagenum" id="Page_3">3</span>
+precision of measurement; for the astronomer of to-day can still
+use his circles for the special purpose of fixing the sun’s place
+in the heavens, without any more knowledge of that body’s
+chemical constitution than had the man who built Stonehenge.</p>
+
+<p>Yet the object of both is, in fact, the same. It is true that
+the functions of astronomer and priest have become divided in
+the advance of our modern civilization, which has committed the
+special cultivation of the religious aspect of these problems to
+a distinct profession; while the modern observer has possibly
+exchanged the emotions of awe and wonder for a more exact
+knowledge of the equinox than was possessed by his primitive
+brother, who both observed and adored. Still, both aim at the
+common end, not of learning what the sun is made of, but of
+where it will be at a certain moment; for the prime object of
+astronomy, until very lately indeed, has still been to say <em>where</em>
+any heavenly body is, and not <em>what</em> it is. It is this precision
+of measurement, then, which has always—and justly—been
+a paramount object of this oldest of the sciences, not only as a
+good in itself, but as leading to great ends; and it is this which
+the poet of Urania has chosen rightly to note as its characteristic,
+when he <span class="locked">says,—</span></p>
+
+<div class="poetry-container">
+<div class="poetry">
+  <div class="stanza">
+    <div class="verse indentq">“That little Vernier, on whose slender lines</div>
+    <div class="verse indent0">The midnight taper trembles as it shines,</div>
+    <div class="verse indent0">Tells through the mist where dazzled Mercury burns,</div>
+    <div class="verse indent0">And marks the point where Uranus returns.”</div>
+  </div>
+</div>
+</div>
+
+<p>But within a comparatively few years a new branch of
+astronomy has arisen, which studies sun, moon, and stars for
+what they are in themselves, and in relation to ourselves. Its
+study of the sun, beginning with its external features (and full of
+novelty and interest, even, as regards those), led to the further
+inquiry as to what it was made of, and then to finding the unexpected
+relations which it bore to the earth and our own daily
+lives on it, the conclusion being that, in a physical sense, it made<span class="pagenum" id="Page_4">4</span>
+us and re-creates us, as it were, daily, and that the knowledge of
+the intimate ties which unite man with it brings results of the
+most practical and important kind, which a generation ago were
+unguessed at.</p>
+
+<p>This new branch of inquiry is sometimes called Celestial
+Physics, sometimes Solar Physics, and is sometimes more
+rarely referred to as the New Astronomy. I will call it here
+by this title, and try to tell the reader something about it which
+may interest him, beginning with the sun.</p>
+
+<div id="ip_1" class="figcenter" style="max-width: 25em;">
+  <img src="images/i_004.jpg" alt="" />
+  <div class="caption">FIG. 1.—THE SUN’S SURROUNDINGS.</div></div>
+
+<p>The whole of what we have to say about the sun and stars
+presupposes a knowledge of their size and distance, and we may
+take it for granted that the reader has at some time or another
+heard such statements as that the moon’s distance is two hundred
+and forty thousand miles, and the sun’s ninety-three million
+(and very probably has forgotten them again as of no practical
+concern). He will not be offered here the kind of statistics
+which he would expect in a college text-book; but we must
+linger a moment on the threshold of our subject—the nature
+of these bodies—to insist on the real meaning of such figures
+as those just quoted. We are accustomed to look on the sun<span class="pagenum" id="Page_5">5</span>
+and moon as far off together in the sky; and though we know
+the sun is greater, we are apt to think of them vaguely as things
+of a common order of largeness, away among the stars. It
+would be safe to say that though nine out of ten readers have
+learned that the sun is larger than the moon, and, in fact, larger
+than the earth itself, most of them do not at all realize that the
+difference is so enormous that if we could hollow out the sun’s
+globe and place the earth in the centre, there would still be so
+much room that the moon might go on moving in her present
+orbit at two hundred and forty thousand miles from the earth,—<em>all
+within the globe of the sun itself</em>,—and have plenty of room
+to spare.</p>
+
+<p>As to the distance of ninety-three million miles, a cannon-ball
+would travel it in about fifteen years. It may help us to remember
+that at the speed attained by the Limited Express on our
+railroads a train which had left the sun for the earth when the
+“Mayflower” sailed from Delftshaven with the Pilgrim Fathers,
+and which ran at that rate day and night, would in 1887 still be
+a journey of some years away from its terrestrial station. The
+fare at the customary rates, it may be remarked, would be
+rather over two million five hundred thousand dollars, so that
+it is clear that we should need both money and leisure for the
+journey.</p>
+
+<p>Perhaps the most striking illustration of the sun’s distance is
+given by expressing it in terms of what the physiologists would
+call velocity of nerve transmission. It has been found that sensation
+is not absolutely instantaneous, but that it occupies a very
+minute time in travelling along the nerves; so that if a child
+puts its finger into the candle, there is a certain almost inconceivably
+small space of time, say the one-hundredth of a second,
+before he feels the heat. In case, then, a child’s arm were long
+enough to touch the sun, it can be calculated from this known
+rate of transmission that the infant would have to live to be a<span class="pagenum" id="Page_6">6</span>
+man of over a hundred before it knew that its fingers were
+burned.</p>
+
+<p>Trying with the help of these still inadequate images, we
+may get some idea of the real size and distance of the sun. I
+could wish not to have to dwell upon such figures, that seem,
+however, indispensable; but we are now done with these, and
+are ready to turn to the telescope and see what the sun itself
+looks like.</p>
+
+<div id="ip_2" class="figleft" style="max-width: 14em;">
+  <img src="images/i_006.jpg" alt="" />
+  <div class="caption">FIG. 2.—VIEW OF THE SUN ON SEPT. 20, 1870.</div></div>
+
+<div id="ip_3" class="figright" style="max-width: 14em;">
+  <img src="images/i_006b.jpg" alt="" />
+  <div class="caption"><p>FIG. 3.—THE SUN ON SEPT. 22, 1870.</p>
+
+<p class="smaller">(FROM A PHOTOGRAPH)</p></div></div>
+
+<p>The sun, as we shall learn later, is a star, and not a particularly
+large star. It is, as has been said, “only a private in the
+host of heaven,” but it is one of that host; it is one of those
+glittering points to which we have been brought near. Let us
+keep in mind, then, from the first, what we shall see confirmed
+later, that there is an essentially similar constitution in them all,
+and not forget that when we study the sun, as we now begin to
+do, we are studying the stars also.</p>
+
+<p>If we were called on to give a description of the earth and all
+that is on it, it would be easily understood that the task was
+impossibly great, and that even an account of its most striking
+general features might fill volumes. So it is with the sun; and<span class="pagenum" id="Page_7">7</span>
+we shall find that in the description of the general character of
+its immediate surface alone, there is a great deal to be told.
+First, let us look at a little conventional representation (<a href="#ip_1">Fig. 1</a>),
+as at a kind of outline of the unknown regions we are about to
+explore. The circle represents the Photosphere, which is simply
+what the word implies, that “sphere” of “light” which we have
+daily before our eyes, or which we can study with the telescope.
+Outside this there is a thin envelope, which rises here and there
+into irregular prominences, some orange-scarlet, some rose-pink.
+This is the Chromosphere, a thin shell, mainly of crimson and
+scarlet tints, invisible even to
+the telescope except at the time
+of a total eclipse, when alone
+its true colors are discernible,
+but seen as to its form at all
+times by the spectroscope. It
+is always there, not hidden in
+any way, and yet not seen,
+only because it is overpowered
+by the intenser brilliancy of the
+Photosphere, as a glow-worm’s
+shine would be if it were put
+beside an electric light. Outside all is the strange shape, which
+represents the mysterious Corona, seen by the naked eye in a
+total eclipse, but at all other times invisible even to telescope
+and spectroscope, and of whose true nature we are nearly ignorant
+from lack of opportunity to study it.</p>
+
+<div id="ip_4" class="figright" style="max-width: 14em;">
+  <img src="images/i_007.jpg" alt="" />
+  <div class="caption">FIG. 4.—THE SUN ON SEPT. 26, 1870.</div></div>
+
+<p>Disregarding other details, let us carry in our minds the three
+main divisions,—the Photosphere, or daily visible surface of
+the sun, which contains nearly all its mass or substance; the
+Chromosphere; and the unsubstantial Corona, which is nevertheless
+larger than all the rest. We begin our examination
+with the Photosphere.</p>
+
+<p><span class="pagenum" id="Page_8">8</span></p>
+
+<p>There are records of spots having been seen with the naked
+eye before the invention of the telescope, but they were supposed
+to be planets passing between us and the surface; and the
+idea that the sun was pure fire, necessarily immaculate, was
+taught by the professors of the Aristotelian philosophy in mediæval
+schools, and regarded almost as an article of religious faith.
+We can hardly conceive, now, the shock of the first announcement
+that spots were to be found on the sun, but the notion
+partook in contemporary minds at once of the absurd and the
+impious; and we notice here, what we shall have occasion to
+notice again, that these physical discoveries from the first affect
+men’s thoughts in unexpected ways, and modify their scheme
+of the moral universe as well as of the physical one.</p>
+
+<div class="clear"></div>
+<div id="ip_5" class="figleft" style="max-width: 10em;">
+  <img src="images/i_008.png" alt="" />
+  <div class="caption">FIG. 5.—SEPT. 19, 1870.</div></div>
+
+<div id="ip_6" class="figright" style="max-width: 11em;">
+  <img src="images/i_008b.jpg" alt="" />
+  <div class="caption"><p>FIG. 6.—SEPT. 20, 1870.</p>
+
+<p>(ENGRAVED FROM A PHOTOGRAPH BY RUTHERFURD.)</p></div></div>
+
+<p>Very little indeed was added to the early observations of
+Fabricius and Galileo until a time within the remembrance of
+many of us; for it is since the advent of the generation now on
+the stage that nine-tenths of the knowledge of the subject has
+been reached.</p>
+
+<p>Let us first take a general view of the sun, and afterward
+study it in detail. What we see with a good telescope in this
+general view is something like this. Opposite are three successive<span class="pagenum" id="Page_9">9</span>
+views (Figs. <a href="#ip_2">2</a>, <a href="#ip_2">3</a>, <a href="#ip_4">4</a>) taken on three successive days,—quite
+authentic portraits, since the sun himself made them; they being,
+in fact, projected telescopic images which have been fixed for us
+by photography, and then exactly reproduced by the engraver.
+The first was taken (by Mr. Rutherfurd, of New York) on the
+20th of September, 1870, when a remarkably large spot had
+come into view. It is seen here not far from the eastern edge
+(the left hand in the engraving), and numerous other spots are
+also visible. The reader should notice the position of these,
+and then on turning to the next view (<a href="#ip_3">Fig. 3</a>, taken on September
+22d) he will see that they have all shifted their places, by a
+common motion toward the west. The great spot on the left
+has now got well into view, and we can see its separate parts;
+the group which was on the left of the centre has got a little to
+the right of it, and so on. From the common motion of them
+all, we might suspect that the sun was turning round on an axis
+like the earth, carrying the spots with it; and as we continue to
+observe, this suspicion becomes certainty. In the third view
+(<a href="#ip_4">Fig. 4</a>), taken on September 26th, the spot we first saw on the
+left has travelled more than half across the disk, while others we
+saw on September 20th have approached to the right-hand edge
+or passed wholly out of sight behind it. The sun does rotate,<span class="pagenum" id="Page_10">10</span>
+then, but in twenty-five or twenty-six of our days,—I say
+twenty-five <em>or</em> twenty-six, because (what is very extraordinary)
+it does not turn all-of-a-piece like the earth, but some parts
+revolve faster than others,—not only faster in feet and inches,
+but in the number of turns,—just as though the rim of a carriage
+wheel were to make more revolutions in a mile than the
+spokes, and the spokes more than the hub. Of course no solid
+wheel could so turn without wrenching itself in pieces, but that
+the great solar wheel does, is incontestable; and this alone is a
+convincing proof that the sun’s surface is not solid, but liquid or
+gaseous.</p>
+
+<div id="ip_7" class="figleft" style="max-width: 11em;">
+  <img src="images/i_009.jpg" alt="" />
+  <div class="caption">FIG. 7.—SEPT. 21, 1870.</div></div>
+
+<div id="ip_8" class="figright" style="max-width: 10em;">
+  <img src="images/i_009b.jpg" alt="" />
+  <div class="caption">FIG. 8.—SEPT. 22, 1870.</div></div>
+
+<p>But let us return to the great spot which we saw coming
+round the eastern edge. Possibly the word “great” may seem
+misapplied to what was but the size of a pin-head in the first
+engraving, but we must remember that the disk of the sun
+there shown is in reality over 800,000 miles in diameter. We
+shall soon see whether this spot deserves to be called “great”
+or not.</p>
+
+<div id="ip_9" class="figleft" style="max-width: 13em;">
+  <img src="images/i_010.jpg" alt="" />
+  <div class="caption">FIG. 9.—SEPT. 23, 1870.</div></div>
+
+<div id="ip_10" class="figright" style="max-width: 14em;">
+  <img src="images/i_010b.jpg" alt="" />
+  <div class="caption">FIG. 10.—SEPT. 26, 1870.</div></div>
+
+<p>Next we have six enlarged views of it on the 19th, 20th, 21st,
+22d, 23d, and 26th. On the 19th it is seen very near the eastern
+limb, showing like a great hole in the sun, and foreshortened as
+it comes into view around the dark edge; for the edge of the<span class="pagenum" id="Page_11">11</span>
+sun is really darker than the central parts, as it is shown here,
+or as one may see even through a smoked glass by careful
+attention. On the 20th we have the edge still visible, but on
+the 21st the spot has advanced so far that the edge cannot be
+shown for want of room. We see distinctly the division of the
+spot into the outer shades which constitute the penumbra, and
+the inner darker ones which form the umbra and nucleus. We
+notice particularly in this enlarged view, by comparing the
+appearances on the 21st, 22d, and 23d, that the spot not only
+turns with the sun (as we have already learned), but moves and
+changes within itself in the most surprising way, like a terrestrial
+cloud, which not only revolves with the rest of the globe, but
+varies its shape from hour to hour. This is seen still more
+plainly when we compare the appearance on the 23d with that
+on the 26th, only three days later, where the process has begun
+by which the spot finally breaks up and forever disappears. On<span class="pagenum" id="Page_12">12</span>
+looking at all this, the tremendous scale on which the action
+occurs must be borne in mind. On the 21st, for instance, the
+umbra, or dark central hole, alone was large enough to let
+the whole globe of our own earth drop in without touching the
+sides! We shall have occasion to recur to this view of the 21st
+September again.</p>
+
+<div id="ip_11" class="figcenter clear" style="max-width: 26em;">
+  <img src="images/i_011.jpg" alt="" />
+  <div class="caption">FIG. 11.—NASMYTH’S WILLOW LEAVES. (FROM HERSCHEL’S “OUTLINES OF ASTRONOMY.”)</div></div>
+
+<p>In looking at this spot and its striking changes, the reader
+must not omit to notice, also, a much less obvious feature,—the
+vaguely seen mottlings which show all over the sun’s surface,
+both quite away from the spots and also close to them, and
+which seem to merge into them.</p>
+
+<div id="ip_12" class="figleft" style="max-width: 9em;">
+  <img src="images/i_012.png" alt="" />
+  <div class="caption">FIG. 12.—THE CACTUS TYPE.<br />
+<span class="smaller">(FROM SECCHI’S “LE SOLEIL.”)</span></div></div>
+
+<p>I think if we assign one year rather
+than another for the birth of the youthful
+science of solar physics, it should be
+1861, when Kirchhoff and Bunsen published
+their memorable research on
+Spectrum Analysis, and when Nasmyth
+observed what he called the “willow-leaf”
+structure of the solar surface (see
+<a href="#ip_11">Fig. 11</a>). Mr. Nasmyth, with a very powerful
+reflecting telescope, thought he had
+succeeded in finding what these faint
+mottlings really are composed of, and
+believed that he had discovered in them
+some most extraordinary things. This is
+what he thought he saw: The whole sun is, according to him,
+covered with huge bodies of most definite shape, that of the
+oblong willow leaf, and of enormous but uniform size; and
+the faint mottlings the reader has just noticed are, according to
+him, made up of these. “These,” he says, “cover the whole
+disk of the sun (except in the space occupied by the spots) in
+countless millions, and lie crossing each other in every imaginable
+direction.” Sir John Herschel took a particular interest<span class="pagenum" id="Page_13">13</span>
+in the supposed discovery, and, treating it as a matter of
+established fact, proceeded to make one of the most amazing
+suggestions in explanation that ever came from a scientific
+man of deserved eminence. We must remember how much
+there is unknown in the sun still, and what a great mystery
+even yet overhangs many of our relations to that body which
+maintains our own vital
+action, when we read the
+following words, which are
+Herschel’s own. Speaking
+of these supposed spindle-shaped
+monsters, he says:</p>
+
+<div class="blockquot">
+
+<p>“The exceedingly definite
+shape of these objects, their
+exact similarity to one another,
+and the way in which they lie
+across and athwart each other,—all
+these characters seem
+quite repugnant to the notion
+of their being of a vaporous, a
+cloudy, or a fluid nature. Nothing
+remains but to consider
+them as separate and independent
+sheets, flakes, or scales,
+having some sort of solidity.
+And these ... are evidently <em>the immediate sources of the solar light and
+heat</em>, by whatever mechanism or whatever processes they may be enabled
+to develop, and as it were elaborate, these elements from the bosom of the
+non-luminous fluid in which they appear to float. Looked at in this point
+of view, we cannot refuse to regard them as <em>organisms</em> of some peculiar
+and amazing kind; and though it would be too daring to speak of such
+organization as partaking of the nature of life, yet we do know that vital
+action is competent to develop at once heat and light and electricity.”</p>
+</div>
+
+<div id="ip_13" class="figright" style="max-width: 16em;">
+  <img src="images/i_013.jpg" alt="" />
+  <div class="caption">FIG. 13.—EQUATORIAL TELESCOPE AND
+PROJECTION.</div></div>
+
+<p>Such are his words; and when we consider that each of these
+solar inhabitants was supposed to extend about two hundred by<span class="pagenum" id="Page_14">14</span>
+one thousand miles upon the surface of the fiery ocean, we may
+subscribe to Mr. Proctor’s comment, that “Milton’s picture of
+him who on the fires of hell ‘lay floating many a rood,’ seems
+tame and commonplace compared with Herschel’s conception of
+these floating monsters, the least covering a greater space than
+the British Islands.”</p>
+
+<div id="ip_14" class="figleft" style="max-width: 16em;">
+  <img src="images/i_014.png" alt="" />
+  <div class="caption">FIG. 14.—POLARIZING EYE-PIECE.</div></div>
+
+<p>I hope I may not appear wanting in respect for Sir John
+Herschel—a man whose memory I reverence—in thus citing
+views which, if his honored life could have been prolonged, he
+would have abandoned. I
+do so because nothing else
+can so forcibly illustrate
+the field for wonder and
+wild conjecture solar physics
+presented even a few
+years ago; and its supposed
+connection with that
+“Vital Force,” which was
+till so lately accepted by physiology, serves as a kind of landmark
+on the way we have come.</p>
+
+<p>This new science of ours, then, youthful as it is, has already
+had its age of fable.</p>
+
+<p>After a time Nasmyth’s observation was attributed to imperfect
+definition, but was not fairly disproved. He had, indeed, a
+basis of fact for his statement, and to him belongs the credit of
+first pointing out the existence of this minute structure, though
+he mistook its true character. It will be seen later how the real
+forms might be mistaken for leaves, and <em>in certain particular
+cases</em> they certainly do take on a very leaf-like appearance.
+Here is a drawing (<a href="#ip_12">Fig. 12</a>) which Father Secchi gives of some
+of them in the spot of April 14, 1867, and which he compares
+to a branch of cactus. He remarks somewhere else that they
+resemble a crystallization of sal-ammoniac, and calls them veils<span class="pagenum" id="Page_17">17</span>
+of most intricate structure. This was the state of our knowledge
+in 1870, and it may seem surprising that such wonderful statements
+had not been proved or disproved, when they referred
+to mere matters of observation. But direct observation is here
+very difficult on account of the incessant tremor and vibration
+of our own atmosphere.</p>
+
+<div id="ip_15" class="figcenter" style="max-width: 32em;">
+  <img src="images/i_015.jpg" alt="" />
+  <div class="caption">FIG. 15.—SPOT OF SEPT. 21, 1870. (REDUCED FROM AN ORIGINAL DRAWING BY S. P. LANGLEY.)</div></div>
+
+<div id="ip_16" class="figcenter" style="max-width: 33em;">
+  <img src="images/i_015b.jpg" alt="" />
+  <div class="caption">FIG. 16.—SPOT OF MARCH 5, 1873. (REDUCED FROM AN ORIGINAL DRAWING BY S. P. LANGLEY.)</div></div>
+
+<p>The surface of the sun may be compared to an elaborate
+engraving, filled with the closest and most delicate lines and
+hatchings, but an engraving which during ninety-nine hundredths
+of the time can only be seen across such a quivering
+mass of heated air as makes everything confused and liable to
+be mistaken, causing what is definite to look like a vaguely seen
+mottling. It is literally true that the more delicate features we
+are about to show, are only distinctly visible even by the best
+telescope during less than one-hundredth of the time, coming
+out as they do in brief instants when our dancing air is momentarily
+still, so that one who has sat at a powerful telescope all
+day is exceptionally lucky if he has secured enough glimpses
+of the true structure to aggregate five minutes of clear seeing,
+while at all other times the attempt to magnify only produces
+a blurring of the image. This study, then, demands not only
+fine telescopes and special optical aids, but endless patience.</p>
+
+<div id="ip_17" class="figleft" style="max-width: 16em;">
+  <img src="images/i_018.png" alt="" />
+  <div class="caption">FIG. 17.—SUN ON MARCH 5, 1873. (FROM A DRAWING
+BY S. P. LANGLEY.)</div></div>
+
+<p>My attention was first particularly directed to the subject in
+1870 (shortly after the regular study of the Photosphere was
+begun at the Allegheny Observatory by means of its equatorial
+telescope of thirteen inches’ aperture), with the view of
+finding out what this vaguely seen structure really is. Nearly
+three years of constant watching were given to obtain the results
+which follow. The method I have used for it is indicated in the
+drawing (<a href="#ip_13">Fig. 13</a>), which shows the preliminary step of projecting
+the image of the sun directly upon a sheet of paper, divided
+into squares and attached to the eye-end of a great equatorial
+telescope. When this is directed to the sun in a darkened dome,<span class="pagenum" id="Page_18">18</span>
+the solar picture is formed upon the paper as in a camera
+obscura, and this picture can be made as large or as small as
+we please by varying the lenses which project it. As the sun
+moves along in the sky, its image moves across the paper; and
+as we can observe how long the whole sun (whose diameter in
+miles is known) takes to cross, we can find how many miles
+correspond to the time it
+is in crossing one of the
+squares, and so get the
+scale of the future drawing,
+and the true size in
+miles of the spot we are
+about to study. Then a
+piece of clock-work attached
+to the telescope is
+put in motion, and it begins
+to follow the sun
+in the sky, and the spot
+appears fixed on the paper.
+A tracing of the
+spot’s outline is next
+made, but the finer details are not to be observed by this
+method, which is purely preliminary, and only for the purpose
+of fixing the scale and the points of the compass (so to speak) on
+the sun’s face. The projecting apparatus is next removed and
+replaced by the polarizing eye-piece. Sir William Herschel
+used to avoid the blinding effects of the concentrated solar light
+by passing the rays through ink and water, but the phenomena
+of “polarization” have been used to better advantage in modern
+apparatus. This instrument, one of the first of its kind ever
+constructed, and in which the light is polarized with three successive
+reflections through the three tubes seen in the drawing
+(<a href="#ip_14">Fig. 14</a>), was made in Pittsburgh as a part of the gift of apparatus<span class="pagenum" id="Page_19">19</span>
+by one of its citizens to the Observatory, and has been
+most useful. By its aid the eye can be safely placed where the
+concentrated heat would otherwise melt iron. In practice I
+have often gazed through it at the sun’s face without intermission
+from four to five hours, with no more fatigue or harm to
+the eye than in reading a book. By its aid the observer fills in
+the outline already projected on the paper.</p>
+
+<div id="ip_18" class="figright" style="max-width: 16em;">
+  <img src="images/i_019.jpg" alt="" />
+  <div class="caption">FIG. 18.—“THE PLUME” SPOT OF MARCH 5 AND
+6, 1873. (FROM AN ORIGINAL DRAWING BY S. P.
+LANGLEY.)</div></div>
+
+<p>The photograph has transported us already so near the sun’s
+surface that we have seen details there invisible to the naked
+eye. We have seen that
+what we have called “spots”
+are indeed regions whose
+actual vastness surpasses
+the vague immensity of a
+dream, and it will not cause
+surprise that in them is a
+temperature which also surpasses
+greatly that of the
+hottest furnace. We shall
+see later, in fact, that the
+whole surface is composed
+largely of metals turned
+into vapor in this heat, and
+that if we could indeed
+drop our great globe itself upon the sun, it would be dissipated
+as a snow-flake. Now, we cannot suppose this great space is
+fully described when we have divided it into the penumbra,
+umbra, and nucleus, or that the little photograph has shown us
+all there is, and we rather anticipate that these great spaces must
+be filled with curious things, if we could get near enough to see
+them. We cannot advantageously enlarge our photograph further;
+but if we could really come closer, we should have the
+nearer view that the work at Allegheny, I have just alluded to,<span class="pagenum" id="Page_20">20</span>
+now affords. The drawing (<a href="#ip_15">Fig. 15</a>) of the central part of
+the same great spot, already cited, was made on the 21st of September,
+1870, and may be compared with the photograph of
+that day. We have now a greatly more magnified view than
+before, but it is not blurred by the magnifying, and is full of
+detail. We have been brought within two hundred thousand
+miles of the sun, or rather less than the actual distance of the
+moon, and are seeing for ourselves what was a few years since
+thought out of the reach of any observer. See how full of intricate
+forms that void, black, umbral space in the photograph has
+become! The penumbra is filled with detail of the strangest
+kind, and there are two great “bridges,” as they are called,
+which are almost wholly invisible in the photograph. Notice
+the line in one of the bridges which follows its sinuosities
+through its whole length of twelve thousand miles, making us
+suspect that it is made up of smaller parts as a rope is made up
+of cords (as, in fact, it is); and look at the end, where the cords
+themselves are unravelled into threads fine as threads of silk,
+and these again resolved into finer fibres, till in more and more
+web-like fineness it passes beyond the reach of sight! I am
+speaking, however, here rather of the wonderful original, as I so
+well remember it, than of what my sketch or even the engraver’s
+skill can render.</p>
+
+<div id="ip_19" class="figcenter" style="max-width: 34em;">
+  <img src="images/i_021.jpg" alt="" />
+  <div class="caption"><p>FIG. 19.—TYPICAL SUN SPOT OF DECEMBER, 1873.</p>
+
+<p>(REDUCED FROM AN ORIGINAL DRAWING BY S. P. LANGLEY.)</p></div></div>
+
+<div id="ip_20" class="figcenter" style="max-width: 22em;">
+  <img src="images/i_023.jpg" alt="" />
+  <div class="caption">FIG. 20.—FROST CRYSTAL.</div></div>
+
+<p>Next we have quite another “spot” belonging to another
+year (1873). First, there is a view (<a href="#ip_17">Fig. 17</a>) of the sun’s disk
+with the spot on it (as it would appear in a small telescope), to
+show its relative size, and then a larger drawing of the spot
+itself (<a href="#ip_16">Fig. 16</a>), on a scale of twelve thousand miles to the inch,
+so that the region shown to the reader’s eyes, though but a
+“spot” on the sun, covers an area of over one billion square
+miles, or more than five times the entire surface of the earth,
+land, and water. To help us to conceive its vastness, I have
+drawn in one corner the continents of North and South America<span class="pagenum" id="Page_23">23</span>
+on the same scale as the “spot.” Notice the evidence of solar
+whirlwinds and the extraordinary “plume” (<a href="#ip_16">Fig. 16</a>), which is a
+something we have no terrestrial simile for. The appearance of
+the original would have been described most correctly by such
+incongruous images as “leaf-like” and “crystalline” and “flame-like;”
+and even in this inadequate sketch there may remain
+some faint suggestion of the appearance of its wonderful archetype,
+which was indeed that of a great flame leaping into spires
+and viewed through a window covered with frost crystals.
+Neither “frost” nor “flame” is really there, but we cannot
+avoid this seemingly unnatural union of images, which was fully
+justified by the marvellous thing itself. The reader must bear in
+mind that the whole of this was actually in motion, not merely
+turning with the sun’s rotation, but whirling and shifting within
+itself, and that the motion was in parts occasionally probably as
+high as fifty miles per second,—per <em>second</em>, remember, not per<span class="pagenum" id="Page_24">24</span>
+hour,—so that it changed under the gazer’s eyes. The hook-shaped
+prominence in the lower part (actually larger than the
+United States) broke up and disappeared in about twenty minutes,
+or while the writer was engaged in drawing it. The
+imagination is confounded in an attempt to realize to itself the
+true character of such a phenomenon.</p>
+
+<div id="ip_21" class="figleft" style="max-width: 16em;">
+  <img src="images/i_024.jpg" alt="" />
+  <div class="caption">FIG. 21.—CYCLONE SPOT. (DRAWN BY FATHER
+SECCHI.)</div></div>
+
+<p>On page 19 is a separate view of the plume (<a href="#ip_18">Fig. 18</a>), a fac-simile
+of the original sketch, which was made with the eye at
+the telescope. The pointed
+or flame-like tips are not a
+very common form, the terminals
+being more commonly
+clubbed, like those
+in Father Secchi’s “branch
+of cactus” type given on
+page 12. It must be borne
+in mind, too, if the drawing
+does not seem to contain
+all that the text implies,
+that there were but a few
+minutes in which to attempt
+to draw, where even a
+skilled draughtsman might have spent hours on the details
+momentarily visible, and that much must be left to memory.
+The writer’s note-book at the time contains an expression of
+despair at his utter inability to render most of what he saw.</p>
+
+<p>Let us now look at another and even more wonderful example.
+<a href="#ip_19">Fig. 19</a> shows part of a great spot which the writer drew
+in December, 1873, when the rare coincidence happened of a
+fine spot and fine terrestrial weather to observe it in. In this,
+as well as in the preceding drawing, the pores which cover the
+sun’s surface by millions may be noted. The luminous dots
+which divide them are what Nasmyth imperfectly saw, but we<span class="pagenum" id="Page_25">25</span>
+are hardly more able than he to say what they really are.
+Each of these countless “dots” is larger than England, Scotland,
+and Ireland together! The wonderful “crystalline” structure
+in the centre cannot be a real crystal, for it is ten times the
+area of Europe, and changed slowly while I drew it; but the
+reader may be sure that its resemblance to some crystallizations
+has not been in the least exaggerated. I have sought to study
+various actual crystals for comparison, but found none quite
+satisfactory. That of sal-ammoniac
+in some remote
+way resembles it,
+as Secchi says; but perhaps
+the frost crystals on
+a window-pane are better.
+<a href="#ip_20">Fig. 20</a> shows one
+selected among several
+windows I had photographed
+in a preceding
+winter, which has some
+suggestions of the so-called
+crystalline spot-forms
+in it, but which
+lacks the filamentary
+thread-like components presently described. Of course the
+reader will understand that it is given as a suggestion of the
+appearance merely, and that no similarity of nature is meant
+to be indicated.</p>
+
+<div id="ip_22" class="figright" style="max-width: 17em;">
+  <img src="images/i_025.jpg" alt="" />
+  <div class="caption">FIG. 22.—SPOT OF MARCH 31, 1875. (FROM AN
+ORIGINAL DRAWING BY S. P. LANGLEY.)</div></div>
+
+<p>There were wonderful fern-like forms in this spot, too, and
+an appearance like that of pine-boughs covered with snow; for,
+strangely enough, the intense whiteness of the solar surface in
+the best telescopes constantly suggests cold. I have had the
+same impression vividly in looking at the immense masses of
+molten-white iron in a great puddling-furnace. The salient<span class="pagenum" id="Page_26">26</span>
+feature here is one very difficult to see, even in good telescopes,
+but one which is of great interest. It has been shown in the
+previous drawings, but we have not enlarged on it. Everywhere
+in the spot are long white threads, or filaments, lying
+upon one another, tending in a general sense toward the centre,
+and each of which grows brighter toward its inner extremity.
+These make up, in fact, as we now see, the penumbra, or outer
+shade, and the so-called “crystal” is really affiliated to them.
+Besides this, on closer looking we see that the inner shade, or
+umbra, and the very deepest shades, or nuclei, are really made
+of them too. We can look into the dark centre, as into a funnel,
+to the depth of probably over five thousand miles; but as far as
+we may go down we come to no liquid or solid floor, and see
+only volumes of whirling vapor, disposed not vaguely like our
+clouds, but in the singularly definite, fern-like, flower-like forms
+which are themselves made of these “filaments,” each of which
+is from three to five thousand miles long, and from fifty to two
+hundred miles thick, and each of which (as we saw in the first
+spot) appears to be made up like a rope of still finer and finer
+strands, looking in the rare instants when irradiation makes an
+isolated one visible, like a thread of gossamer or the finest of
+cobweb. These suggest the fine threads of spun glass; and
+here there is something more than a mere resemblance of form,
+for both appear to have one causal feature in common, due to a
+viscous or “sticky” fluid; for there is much reason to believe
+that the solar atmosphere, even where thinner than our own air,
+is rendered viscous by the enormous heat, and owes to this its
+tendency to pull out in strings in common with such otherwise
+dissimilar things as honey, or melted sugar, or melted glass.</p>
+
+<p>We may compare those mysterious things, the filaments, to
+long grasses growing in the bed of a stream, which show us the
+direction and the eddies of the current. The likeness holds in
+more ways than one. They are not lying, as it were, flat upon<span class="pagenum" id="Page_27">27</span>
+the surface of the water, but <em>within</em> the medium; and they do
+not stretch along in any one plane, but they bend down and up.
+Moreover, they are, as we see, apparently rooted at one end, and
+their tips rise above the turbid fluid and grow brighter as they
+are lifted out of it. But perhaps the most significant use of the
+comparison is made if we ask whether the stream is moving in
+an eddy like a whirlpool or boiling up from the ground. The
+question in other words is, “Are these spots themselves the sign
+of a mere chaotic disturbance, or do they show us by the disposition
+of these filaments that each is a great solar maelstrom,
+carrying the surface matter of the sun down into its body? or,
+finally, are they just the opposite,—something comparable to
+fiery fountains or volcanoes on the earth, throwing up to the
+surface the contents of the unknown solar interior?”</p>
+
+<div id="ip_23" class="figcenter" style="max-width: 22em;">
+  <img src="images/i_027.jpg" alt="" />
+  <div class="caption">FIG. 23.—CIRROUS CLOUD. (FROM A PHOTOGRAPH.)</div></div>
+
+<p>Before we try to answer this question, let us remember that
+the astonishing rapidity with which these forms change, and still
+more the fact that they do not by any means always change by
+a bodily removal of one part from another, but by a dissolving
+away and a fading out into invisibility, like the melting of a
+cloud into thin air,—let us remember that all this assimilates<span class="pagenum" id="Page_28">28</span>
+them to something cloud-like and vaporous, rather than crystalline,
+and that, as we have here seen, we can ourselves pronounce
+from such results of recent observation that these are not lumps
+of scoriæ floating on the solar furnace (as some have thought
+them), and still less, literal crystals. We can see for ourselves,
+I believe, that so far there is no evidence here of any solid, or
+even liquid, but that the surface of the sun is purely vaporous.
+<a href="#ip_23">Fig. 23</a> shows a cirrous cloud in our own atmosphere, caught
+for us by photography,
+and which the reader
+will find it interesting
+to compare with the apparently
+analogous solar
+cloud-forms.</p>
+
+<div id="ip_24" class="figcenter" style="max-width: 17em;">
+  <img src="images/i_028.jpg" alt="" />
+  <div class="caption">FIG. 24.—SPOT OF MARCH 31, 1875. (FROM AN
+ORIGINAL DRAWING BY S. P. LANGLEY.)</div></div>
+
+<p>“Vaporous,” we call
+them, for want of a better
+word, but without
+meaning that it is like
+the vapor of our clouds.
+There is no exact terrestrial
+analogy for these extraordinary
+forms, which
+are in fact, as we shall
+see later, composed of iron and other metals—not of solid
+iron nor even of liquid, but iron heated beyond even the
+liquid state to that of iron-steam or vapor.</p>
+
+<p>With all this in mind, let us return to the question, “Are
+the spots, these gigantic areas of disturbance, comparable to
+whirlpools or to volcanoes?” It may seem unphilosophical to
+assume that they are one or the other, and in fact they may
+possibly be neither; but it is certain that the surface of the sun
+would soon cool from its enormous temperature, if it were not
+supplied with fresh heat, and it is almost certain that this heat<span class="pagenum" id="Page_29">29</span>
+is drawn from the interior. As M. Faye has pointed out,<a id="FNanchor_1" href="#Footnote_1" class="fnanchor">1</a> there
+<em>must</em> be a circulation up and down, the cooled products being
+carried within, heated and brought out again, or the sun would,
+however hot, grow cold outside; and, what is of interest to us,
+the earth would grow cold
+also, and we should all die.
+No one, I believe, who has
+studied the subject, will
+contradict the statement
+that if the sun’s surface
+were absolutely cut off
+from any heat supply from
+the interior, organic life in
+general upon the earth
+(and our own life in particular)
+would cease much
+within a month. This solar circulation, then, is of nearly as much
+consequence to us as that of our own bodies, if we but knew it;
+and now let us look at the spots again with this in mind.</p>
+
+<div class="footnote">
+
+<p><a id="Footnote_1" href="#FNanchor_1" class="fnanchor">1</a> To Mr. Herbert Spencer must be assigned the earliest suggestion of the necessity
+of such a circulation.</p>
+
+</div>
+
+<div id="ip_25" class="figright" style="max-width: 17em;">
+  <img src="images/i_029.png" alt="" />
+  <div class="caption">FIG. 25.—TYPICAL ILLUSTRATION OF FAYE’S THEORY.</div></div>
+
+<p><a href="#ip_21">Fig. 21</a> shows a drawing by Father Secchi of a spot in 1854;
+and it is, if unexaggerated, quite the most remarkable case of
+distinct cyclonic action recorded. I say “if unexaggerated”
+because there is a strong tendency in most designers to select
+what is striking in a spot, and to emphasize that unduly, even
+when there is no conscious disposition to alter. Every one who
+sketches may see a similar unconscious tendency in himself or
+herself, shown in a disposition to draw all the mountains and
+hills too high,—a tendency on which Ruskin, I think, has
+remarked. In drawings of the sun there is a strong temptation
+to exaggerate these circular forms, and we must not forget this
+in making up the evidence. There is great need of caution, then,
+in receiving such representations; but there certainly are forms
+which seem to be clearly due to cyclonic action. They are<span class="pagenum" id="Page_30">30</span>
+usually scattered, however, through larger spots, and I have
+never, in all my study of the sun, seen one such complete type
+of the cyclone spot as that first given from Secchi. Instances
+where spots break up into numerous subdivisions by a process
+of “segmentation” under the apparent action of separate whirlwinds
+are much more common. I have noticed, as an apparent
+effect of this segmentation, what I may call the “honeycomb
+structure” from its appearance with low powers, but which with
+higher ones turns out to be made up of filamentary masses disposed
+in circular and ovoid curves, often apparently overlying
+one another, and frequently presenting a most curious resemblance
+to vegetable forms, though we appear to see the real
+agency of whirlwinds in making them. I add some transcripts
+of my original pencil memoranda themselves, made with the eye
+at the telescope, which,
+though not at all finished
+drawings, may be trusted
+the more as being quite
+literal transcripts at first
+hand.</p>
+
+<div id="ip_26" class="figleft" style="max-width: 16em;">
+  <img src="images/i_030.jpg" alt="" />
+  <div class="caption">FIG. 26.—SPOT OF OCT. 13, 1876. (FROM ORIGINAL
+DRAWING BY S. P. LANGLEY.)</div></div>
+
+<p>Figs. <a href="#ip_22">22</a> and <a href="#ip_24">24</a>, for instance,
+are two sketches of
+a little spot, showing what,
+with low powers, gives the
+appearance I have called
+the honeycomb structure,
+but which we see here to
+be due to whirls which have
+disposed the filaments in these remarkable forms. The first was
+drawn at eleven in the forenoon of March 31, 1875, the second
+at three in the afternoon of the same day. The scale of the
+drawing is fifteen thousand miles to the inch, and the changes
+in this little spot in these few hours imply a cataclysm compared<span class="pagenum" id="Page_31">31</span>
+with which the disappearance of the American continent from the
+earth’s surface would be a trifle.</p>
+
+<p>The very act of the solar whirlwind’s motion seemed to pass
+before my eyes in some of these sketches; for while drawing
+them as rapidly as possible, a new hole would be formed where
+there was none before, as if by a gigantic invisible auger boring
+downward.</p>
+
+<div id="ip_27" class="figright" style="max-width: 16em;">
+  <img src="images/i_031.jpg" alt="" />
+  <div class="caption">FIG. 27.—PHOTOGRAPH OF EDGE OF SUN. (BY PERMISSION
+OF WARREN DE LA RUE, LONDON.)</div></div>
+
+<p>M. Faye, the distinguished
+French astronomer, believes
+that, owing to the fact that
+different zones of the sun
+rotate faster than others,
+whirlwinds analogous to our
+terrestrial cyclones, but on a
+vaster scale, are set in motion,
+and suck down the
+cooled vapors of the solar
+surface into its interior, to be
+heated and returned again,
+thus establishing a circulation
+which keeps the surface
+from cooling down. He
+points out that we should
+not conclude that these whirlwinds
+are not acting everywhere, merely because our bird’s-eye
+view does not always show them. We see that the spinning
+action of a whirlpool in water becomes more marked as we go
+below the surface, which is comparatively undisturbed, and we
+often see one whirl break up into several minor ones, but all
+sucking downward and never upward. According to M. Faye,
+something very like this takes place on the sun, and in <a href="#ip_25">Fig. 25</a>
+he gives this section to show what he believes to occur in the
+case of a spot which has “segmented,” or divided into two, like<span class="pagenum" id="Page_32">32</span>
+the one whose (imaginary) section is shown above it. This
+theory is to be considered in connection with such drawings
+as we have just shown, which are themselves, however, no way
+dependent on theory, but transcripts from Nature.</p>
+
+<p>I do not here either espouse or oppose the “cyclonic” theory,
+but it is hardly possible for any one who has been an eyewitness
+of such things to refuse to regard some such disturbance as a
+real and efficient cause in such instances as this.</p>
+
+<p><a href="#ip_26">Fig. 26</a>, on nearly the same scale as the last, shows a spot
+which was seen on Oct. 13, 1876. It looked at first, in the telescope,
+like two spots without any connection; then, as vision
+improved and higher powers were employed, the two were seen
+to have a subtle bond of union, and each to be filled with the
+most curious foliage-forms, which I could only indicate in the
+few moments that the good definition lasted. The reader may
+be sure, I think, that there is no exaggeration of the curious
+shapes of the original; for I have been so anxious to avoid the
+overstatement of curvature that the error is more likely to be in
+the opposite direction.</p>
+
+<p>We must conclude that the question as to the cyclonic
+hypothesis cannot yet be decided, though the probabilities from
+telescopic evidence at present seem to me on the whole in favor
+of M. Faye’s remarkable theory, which has the great additional
+attraction to the student that it unites and explains numerous
+other quite disconnected facts.</p>
+
+<p>Turning now to the other solar features, let us once more
+consider the sun as a whole. <a href="#ip_27">Fig. 27</a> is a photograph taken
+from a part of the sun near its edge. We notice on it, what we
+see on every careful delineation of the sun, that its general surface
+is not uniformly bright, but that it grows darker as we
+approach the edge, where it is marked by whiter mottlings called
+faculæ, “something in the sun brighter than the sun itself,” and
+looking in the enlarged view which we present of one of them<span class="pagenum" id="Page_33">33</span>
+(<a href="#ip_28">Fig. 28</a>), as if the surface of partly cooled metal in a caldron
+had been broken into fissures showing the brighter glow beneath.
+These “faculæ,” however, are really above the solar surface, not
+below it, and what we wish to direct particular attention to is
+that darkening toward the edge which makes them visible.</p>
+
+<div id="ip_28" class="figleft" style="max-width: 17em;">
+  <img src="images/i_033.jpg" alt="" />
+  <div class="caption">FIG. 28.—FACULA. (FROM A DRAWING BY
+CHACORNAC.)</div></div>
+
+<p>This is very significant, but its full meaning may not at first
+be clear. It is owing to an atmosphere which surrounds the sun,
+as the air does the earth.
+When we look horizontally
+through our own air, as at
+sunrise and sunset, we gaze
+through greater thicknesses
+of it than when we turn
+our eyes to the zenith. So
+when we look at the edge
+of the sun, the line of sight
+passes through greater
+depths of this solar atmosphere,
+and it dims the
+light shining behind it
+more than at the centre,
+where it is thin.</p>
+
+<p>This darkening toward
+the edge, then, means that
+the sun has an atmosphere
+which tempers its heat to us. Whatever the sun’s heat supply is
+within its globe, if this atmosphere grow thicker, the heat is more
+confined within, and our earth will grow colder; if the solar atmosphere
+grow thinner, the sun’s energy will be expended more
+rapidly, and our earth will grow hotter. This atmosphere, then,
+is in considerable part, at least, the subject of the action of the
+spots; this is what they are supposed to carry down or to
+spout up.</p>
+
+<p><span class="pagenum" id="Page_34">34</span></p>
+
+<p>We shall return to the study of it again; but what I want to
+point out now is that the temperature of the earth, and even the
+existence of man upon it, depends very much upon this, at first
+sight, insignificant phenomenon. What, then, is the solar atmosphere?
+Is it a permanent thing? Not at all. It is more light
+and unsubstantial than our own air, and is being whirled about
+by solar winds as ours toss the dust of the streets. It is being
+sucked down within the body of the sun by some action we do
+not clearly understand, and returned to the surface by some
+counter effect which we comprehend no better; and upon this
+imperfectly understood exchange depends in some way our own
+safety.</p>
+
+<p>There used to be recorded in medical books the case of a boy
+who, to represent Phœbus in a Roman mask, was gilded all
+over to produce the effect of the golden-rayed god, but who died
+in a few hours because, all the pores of the skin being closed by
+the gold-leaf, the natural circulation was arrested. We can count
+with the telescope millions of pores upon the sun’s surface, which
+are in some way connected with the interchange which has just
+been spoken of; and if this, his own natural circulation, were
+arrested or notably diminished, we should see his face grow cold,
+and know that our own health, with the life of all the human
+race, was waiting on his recovery.</p>
+
+<hr />
+
+<div id="toclink_35" class="chapter">
+<p><span class="pagenum" id="Page_35">35</span></p>
+
+<h2 class="nobreak" id="II">II.<br />
+
+<span class="subhead">THE SUN’S SURROUNDINGS.</span></h2>
+</div>
+
+<p class="drop-cap al"><span class="smcap1">As</span> I write this, the fields glitter with snow-crystals in the
+winter noon, and the eye is dazzled with a reflection of
+the splendor which the sun pours so fully into every nook that
+by it alone we appear to see everything.</p>
+
+<p>Yet, as the day declines, and the glow of the sunset spreads
+up to the zenith, there comes out in it the white-shining evening
+star, which not the light, but the darkness, makes visible; and
+as the last ruddy twilight fades, not only this neighbor-world,
+whose light is fed from the sunken sun, but other stars appear,
+themselves self-shining suns, which were above us all through
+the day, unseen because of the very light.</p>
+
+<p>As night draws on, we may see the occasional flash of a
+shooting-star, or perhaps the auroral streamers spreading over
+the heavens; and remembering that these will fade as the sun
+rises, and that the nearer they are to it the more completely
+they will be blotted out, we infer that if the sun were surrounded
+by a halo of only similar brightness, this would remain forever
+invisible,—unless, indeed, there were some way of cutting off
+the light from the sun without obscuring its surroundings. But
+if we try the experiment of holding up a screen which just conceals
+the sun, nothing new is seen in its vicinity, for we are also
+lighted by the neighboring sky, which is so dazzlingly bright
+with reflected light as effectually to hide anything which may
+be behind it, so that to get rid of this glare we should need to
+hang up a screen <em>outside</em> the earth’s atmosphere altogether.</p>
+
+<p><span class="pagenum" id="Page_36">36</span></p>
+
+<div id="ip_29" class="figcenter" style="max-width: 34em;">
+  <img src="images/i_036.jpg" alt="" />
+  <div class="caption">FIG. 29.—LUNAR CONE SHADOW.</div></div>
+
+<p>Nature hangs such a screen in front of the earth when the
+moon passes between it and the sun; but as the moon is far
+too small to screen all the earth completely, and as so limited a
+portion of its surface is in complete shadow that the chances are
+much against any given individual’s being on the single spot
+covered by it, many centuries usually elapse before such a <em>total</em>
+eclipse occurs at any given point; while yet almost every year
+there may be a partial eclipse, when, over a great portion of the
+earth at once, people may be able to look round the moon’s edge
+and see the sunlight but partly cut off. Nearly every one, then,
+has seen a partial eclipse of the sun, but comparatively few a
+total one, which is quite another thing, and worth a journey
+round the world to behold; for such a nimbus, or glory, as we
+have suggested the possibility of, does actually exist about the
+sun, and becomes visible to the naked eye on the rare occasions
+when it is visible at all, accompanied by phenomena which are
+unique among celestial wonders.</p>
+
+<p>The “corona,” as this solar crown is called, is seen during a
+total eclipse to consist of a bright inner light next the invisible
+sun, which melts into a fainter and immensely extended radiance
+(the writer has followed the latter to the distance of about ten
+million miles), and all this inner corona is filled with curious<span class="pagenum" id="Page_37">37</span>
+detail. All this is to be distinguished from another remarkable
+feature seen at the same time; for close to the black body of the
+moon are prominences of a vivid crimson and scarlet, rising up
+like mountains from the hidden solar disk, and these, which will
+be considered later, are quite distinct from the corona, though
+seen on the background of its pearly light.</p>
+
+<p>To understand what the lunar screen is doing for us, we may
+imagine ourselves at some station outside the earth, whence we
+should behold the moon’s shadow somewhat as in <a href="#ip_29">Fig. 29</a>,
+where we must remember that since the lunar orbit is not
+a circle, but nearly an ellipse, the moon is at some times farther
+from the earth than at others. Here the extremity of
+its shadow is represented as just touching the surface of the
+globe, while it is evident that if the moon were at its greatest
+distance, its shadow might come to a point before reaching the
+earth at all. We speak, of course, only of the central cone of
+shade; for there is an outer one, indicated by the faint dotted
+lines, within whose much more extended limits the eclipse is
+partial, but with the latter we have at present nothing to do.
+The figure however, for want of room, is made to represent the
+proportions incorrectly, the real ones of the shadow being actually
+something like those of a sewing-needle,—this very long
+attenuated shadow sometimes, as we have just said, not reaching
+the earth at all, and when it does reach it, covering at the most
+a very small region indeed. Where this point touches, and
+wherever it rests, we should, in looking down from our celestial
+station, see that part of the earth in complete shadow, appearing
+like a minute dark spot, whose lesser diameter is seldom over a
+hundred and fifty miles.</p>
+
+<p>The eclipse is total only to those inhabitants of the earth
+within the track of this dark spot, though the spot itself travels
+across the earth with the speed of the moon in the sky; so that
+if it could leave a mark, it would in a few hours trace a dark<span class="pagenum" id="Page_38">38</span>
+line across the globe, looking like a narrow black tape curving
+across the side of the world next the sun. In <a href="#ip_30">Fig. 30</a>, for instance,
+is the central track of the eclipse of July 29, 1878, as it
+would be visible to our celestial observer, beginning in Alaska
+in the forenoon, and ending in the Gulf of Mexico, which it
+reached in the afternoon. To those on the earth’s surface within
+this shadow it covered everything in view, and, for anything
+those involved in it could see, it was all-embracing and terrible,
+and worthily described in such lines as <span class="locked">Milton’s,—</span></p>
+
+<div class="poetry-container">
+<div class="poetry">
+  <div class="stanza">
+    <div class="verse indent16">“As when the sun ...</div>
+    <div class="verse indent0">In dim eclipse, disastrous twilight sheds</div>
+    <div class="verse indent0">On half the nations, and with fear of change</div>
+    <div class="verse indent0">Perplexes monarchs.”</div>
+  </div>
+</div>
+</div>
+
+<p>We may enjoy the poet’s vision; but here, while we look
+down on the whole earth at once, we must admit that the actual
+area of the “twilight” is very small indeed. Within this area,
+however, the spectacle is one of which, though the man of science
+may prosaically state the facts, perhaps only the poet could
+render the impression.</p>
+
+<p>We can faintly picture, perhaps, how it would seem, from a
+station near the lunar orbit, to see the moon—a moving world—rush
+by with a velocity greater than that of the cannon-ball
+in its swiftest flight; but with equal speed its shadow actually
+travels along the earth. And now, if we return from our imaginary
+station to a real one here below, we are better prepared to
+see why this flying shadow is such a unique spectacle; for, small
+as it may be when seen in relation to the whole globe, it is
+immense to the observer, whose entire horizon is filled with it,
+and who sees the actual velocity of one of the heavenly bodies,
+as it were, brought down to him.</p>
+
+<p>The reader who has ever ascended to the Superga, at Turin,
+will recall the magnificent view, and be able to understand the
+good fortune of an observer (Forbes) who once had the opportunity<span class="pagenum" id="Page_39">39</span>
+to witness thence this phenomenon, and under a nearly
+cloudless sky. “I perceived,” he says, “in the southwest a
+black shadow like that of a storm about to break, which obscured
+the Alps. It was the lunar shadow coming toward us.”
+And he speaks of the “stupefaction”—it is his word—caused
+by the spectacle. “I confess,” he continues, “it was the most
+terrifying sight I ever saw. As always happens in the cases of
+sudden, silent, unexpected
+movements, the spectator
+confounds real and relative
+motion. I felt almost giddy
+for a moment, as though
+the massive building under
+me bowed on the side of
+the coming eclipse.” Another
+witness, who had
+been looking at some
+bright clouds just before,
+says: “The bright cloud
+I saw distinctly put out
+like a candle. The rapidity
+of the shadow, and the
+intensity, produced a feeling
+that something material was sweeping over the earth at a
+speed perfectly frightful. I involuntarily listened for the rushing
+noise of a mighty wind.”</p>
+
+<div id="ip_30" class="figleft" style="max-width: 16em;">
+  <img src="images/i_039.png" alt="" />
+  <div class="caption">FIG. 30—TRACK OF LUNAR SHADOW.</div></div>
+
+<p>Each one notes something different from another at such a
+time; and though the reader will find minute descriptions of the
+phenomena already in print, it will perhaps be more interesting
+if, instead of citations from books, I invite him to view them
+with me, since each can tell best what he has personally seen.</p>
+
+<div id="ip_31" class="figright" style="max-width: 17em;">
+  <img src="images/i_040.png" alt="" />
+  <div class="caption">FIG. 31.—INNER CORONA ECLIPSE OF 1869. FROM
+SHELBYVILLE PHOTOGRAPH. (ROYAL ASTRONOMICAL
+SOCIETY’S MEMOIRS.)</div></div>
+
+<p>I have witnessed three total eclipses, but I do not find that
+repetition dulls the interest. The first was that of 1869, which<span class="pagenum" id="Page_40">40</span>
+passed across the United States and was nearly central over
+Louisville. My station was on the southern border of the
+eclipse track, not very far from the Mammoth Cave in Kentucky,
+and I well remember that early experience. The special
+observations of precision in which I was engaged would not interest
+the reader; but while trying to give my undivided attention
+to these, a mental photograph
+of the whole spectacle
+seemed to be taking
+without my volition. First,
+the black body of the
+moon advanced slowly on
+the sun, as we have all
+seen it do in partial eclipses,
+without anything noticeable
+appearing; nor till the
+sun was very nearly covered
+did the light of day
+about us seem much diminished.
+But when the
+sun’s face was reduced to
+a very narrow crescent, the change was sudden and startling,
+for the light which fell on us not only dwindled rapidly,
+but became of a kind unknown before, so that a pallid appearance
+overspread the face of the earth with an ugly livid
+hue; and as this strange wanness increased, a cold seemed
+to come with it. The impression was of something <em>unnatural</em>;
+but there was only a moment to note it, for the sun went
+out as suddenly as a blown-out gas-jet, and I became as suddenly
+aware that all around, where it had been, there had
+been growing into vision a kind of ghostly radiance, composed
+of separate pearly beams, looking distinct each from each,
+as though the black circle where the sun once was, bristled<span class="pagenum" id="Page_41">41</span>
+with pale streamers, stretching far away from it in a sort of
+crown.</p>
+
+<p>This was the mysterious corona, only seen during the brief
+moments while the shadow is flying overhead; but as I am
+undertaking to recall faithfully the impressions of the instant,
+I may admit that I was at the time equally struck with a circumstance
+that may appear trivial
+in description,—the extraordinary
+globular appearance of the moon
+herself. We all know well enough
+that the moon is a solid sphere,
+but it commonly <em>looks</em> like a bright,
+flat circle fastened to the concave
+of the starry vault; and now, owing
+to its unwonted illumination,
+the actual rotundity was seen for
+the first time, and the result was
+to show it as it really is,—a
+monstrous, solid globe, suspended
+by some invisible support above
+the earth, with nothing apparent to keep it from tumbling on
+us, looking at the moment very near, and more than anything
+else like a gigantic black cannon-ball, hung by some miracle
+in the air above the neighboring cornfield. But in a few seconds
+all was over; the sunlight flashed from one point of the
+moon’s edge and then another, almost simultaneously, like suddenly
+kindled electric lights, which as instantly flowed into one,
+and it was day again.</p>
+
+<div id="ip_32" class="figleft" style="max-width: 12em;">
+  <img src="images/i_041.jpg" alt="" />
+  <div class="caption">FIG. 32.—SKETCH OF OUTER CORONA,
+1869. (U. S. COAST SURVEY REPORT.)</div></div>
+
+<p>I have spoken of the “unnatural” appearance of the light
+just before totality. This is not due to excited fancy, for there
+is something so essentially different from the natural darkness
+of twilight, that the brute creation shares the feeling with us.
+Arago, for instance, mentions that in the eclipse of 1842, at<span class="pagenum" id="Page_42">42</span>
+Perpignan, where he was stationed, a dog which had been kept
+from food twenty-four hours was, to test this, thrown some bread
+just before “totality” began. The dog seized the loaf, began
+to devour it ravenously, and then, as the appearance already
+described came on, he dropped it. The darkness lasted some
+minutes, but not till the sun came forth again did the poor creature
+return to the food. It is no wonder, then, that men also,
+whether educated or ignorant, do not escape the impression. A
+party of the courtiers of Louis XV. is said to have gathered
+round Cassini to witness an eclipse from the terrace of the Paris
+observatory, and to have been laughing at the populace, whose
+cries were heard as the light began to fade; when, as the unnatural
+gloom came quickly on, a sudden silence fell on them too,
+the panic terror striking through their laughter. Something
+common to man and the brute speaks at such times, if never
+before or again; something which is not altogether physical
+apprehension, but more like the moral dismay when the shock
+of an earthquake is felt for the first time, and we first know that
+startling doubt, superior to reason, whether the solid frame of
+earth is real, and not “baseless as the fabric of a vision.”</p>
+
+<p>But this is appealing for illustration to an experience which
+most readers have doubtless been spared,<a id="FNanchor_2" href="#Footnote_2" class="fnanchor">2</a> and I would rather
+cite the lighter one of our central party that day, a few miles
+north of me, at Shelbyville. In this part of Kentucky the
+colored population was large, and (in those days) ignorant of
+everything outside the life of the plantation, from which they
+had only lately been emancipated. On that eventful 8th of
+August they came in great numbers to view the enclosure and
+the tents of the observing party, and to inquire the price of the
+show. On learning that they might see it without charge from
+the outside, a most unfavorable opinion was created among
+them as to the probable merits of so cheap a spectacle, and<span class="pagenum" id="Page_43">43</span>
+they crowded the trees about the camp, shouting to each other
+sarcastic comments on the inferior interest of the entertainment.
+“Those trees there,” said one of the observers to me the next
+day, “were black with them, and they kept up their noise till
+near the last, when they suddenly stopped, and all at once, and
+as ‘totality’ came, we heard a wail and a noise of tumbling, as
+though the trees had been shaken of their fruit, and then the
+boldest did not feel safe till he was under his own bed in his
+own cabin.”</p>
+
+<div class="footnote clear">
+
+<p><a id="Footnote_2" href="#FNanchor_2" class="fnanchor">2</a> This was written before the “Charleston earthquake” occurred.</p>
+
+</div>
+
+<div id="ip_33" class="figcenter" style="max-width: 21em;">
+  <img src="images/i_043.jpg" alt="" />
+  <div class="caption"><p>FIG. 33.—TACCHINI’S DRAWING OF CORONA OF 1870.</p>
+
+<p>(SECCHI’S “LE SOLEIL.”)</p></div></div>
+
+<p>It is impossible to give an exact view of what our friends at
+Shelbyville saw, for no drawings made there appear to have
+been preserved, and photography at that time could only indicate
+feebly the portion of the corona near the sun where it is
+brightest. <a href="#ip_31">Fig. 31</a> is a fac-simile of one of the photographs
+taken on the occasion, which is interesting perhaps as one of<span class="pagenum" id="Page_44">44</span>
+the early attempts in this direction, for comparison with later
+ones; but as a picture it is very disappointing, for the whole
+structure of the outer corona we have alluded to is missed altogether,
+the plate having taken no impression of it.</p>
+
+<p>A drawing (<a href="#ip_32">Fig. 32</a>) made by another observer, Mr. M’Leod,
+at Springfield, represents more of the outer structure; but the
+reader must remember that all drawings must, in the nature of
+the case (since there are but two or three minutes to sketch in),
+be incomplete, whatever the artist’s skill.</p>
+
+<div id="ip_34" class="figleft" style="max-width: 12em;">
+  <img src="images/i_044.png" alt="" />
+  <div class="caption">FIG. 34.—WATSON’S NAKED-EYE DRAWING
+OF CORONA OF 1870. (U. S. COAST SURVEY
+REPORT.)</div></div>
+
+<p>Up to this time it was still doubtful, not only what the corona
+was, but where it was; whether it was a something about
+the sun or moon, or whether, indeed, it might not be in our
+own atmosphere. The spectroscopic observations of Professors
+Young and Harkness at this same eclipse of a green line in its
+spectrum, due to some glowing gas, showed conclusively that
+it was largely, at any rate, a solar appendage, and partly, at
+least, self-luminous; and these and
+other results having awakened general
+discussion among astronomers in Europe
+as well as at home, the United
+States Government sent an expedition,
+under the direction of the late
+Professor Pierce, to observe an eclipse
+which in the next year, on Dec. 8,
+1870, was total in the south of Spain.
+There were three parties; and of the
+most western of these, which was at
+Xeres under the charge of Professor Winlock, I was a member.</p>
+
+<div id="ip_35" class="figcenter clear" style="max-width: 31em;">
+  <img src="images/i_045.jpg" alt="" />
+  <div class="caption"><p>FIG. 35.—PHOTOGRAPH SHOWING COMMENCEMENT OF OUTER CORONA.</p>
+
+<p>(ROYAL ASTRONOMICAL SOCIETY’S MEMOIRS.)</p></div></div>
+
+<p>The duration of totality was known beforehand. It would
+last two minutes and ten seconds, and to secure what could be
+seen in this brief interval we crossed the ocean. Our station
+was in the midst of the sherry district, and a part of the instruments
+were in an orange-grove, where the ground was covered<span class="pagenum" id="Page_47">47</span>
+with the ripe fallen fruit, while the olive and vine about us in
+December reminded us of the distance we had come to gather
+the results of so brief an opportunity.</p>
+
+<p>To prepare for it, we had all arrived on the ground some
+weeks beforehand, and had been assiduously busy in installing
+the apparatus in the observing camp, which suggested that of a
+small army, the numerous instruments, some of them of considerable
+size,—equatorials, photographic apparatus, polariscopes,
+photometers, and spectroscopes,—being under tents, the fronts
+of which could be lifted when the time came for action.</p>
+
+<p>To the equatorial telescopes photographic cameras are attached
+instead of the eye-pieces, in the hope that the corona
+may be made to impress itself on the plate instead of on the
+eye. The eye is an admirable instrument itself, no doubt; but
+behind it is a brain, perhaps overwrought with excitement, and
+responding too completely to the nervous tension which most
+of us experience when those critical moments are passing so
+rapidly. The camera can see far less of the corona than the
+man, <em>but it has no nerves</em>, and what it sets down we may
+rely on.</p>
+
+<p>At such a time each observer has some particular task
+assigned to him, on which, if wise, he has drilled himself for
+weeks beforehand, so that no hesitation or doubt may arise in
+the moment of action; and his attention is expected to be devoted
+to this duty alone, which may keep him from noting any
+of the features which make the occasion so impressive as a
+spectacle. Most of my own particular work was again of a
+kind which would not interest the reader.</p>
+
+<p>Apart from this, I can recall little but the sort of pain of
+expectation, as the moment approached, till within a minute
+before totality the hum of voices around ceased, and an utter
+and most impressive silence succeeded, broken only by a low
+“Ah!” from the group without the camp, when the moment<span class="pagenum" id="Page_48">48</span>
+came. I remember that the clouds, which had hung over the
+sun while the moon was first advancing on its body, cleared
+away before the instant of totality, so that the last thing I saw
+was a range of mountains to the eastward still bright in the
+light; then, the next moment, the shadow rushed overhead and
+blotted out the distant hills, almost before I could turn my face
+to the instrument before me.</p>
+
+<div id="ip_36" class="figcenter" style="max-width: 21em;">
+  <img src="images/i_048.jpg" alt="" />
+  <div class="caption">FIG. 36.—ECLIPSE OF 1857, DRAWING BY LIAIS. (ROYAL ASTRONOMICAL
+SOCIETY’S MEMOIRS.)</div></div>
+
+<p>The corona appeared to me a different thing from what it did
+the year before. It was apparently confined to a pearly light of
+a roughly quadrangular shape, close to the limb of the sun,
+broken by dark rifts (one of which was a conspicuous object);
+while within, and close to the limb, was what looked like a
+mountain rising from the hidden sun, of the color of the richest
+tint we should see in a rose-leaf held up against the light,
+while others were visible of an orange-scarlet. After a short
+scrutiny I turned to my task of analyzing the nature of the
+white light.</p>
+
+<p><span class="pagenum" id="Page_49">49</span></p>
+
+<p>The seconds fled, the light broke out again, and so did the
+hubbub of voices,—it was all over, and what had been missed
+then could not be recovered. The sense of self-reproach for
+wasted opportunity is a common enough feeling at this time,
+though one may have done his best, so little it seems to each
+he has accomplished; but when all the results had been brought
+together, we found that the
+spectroscopes, cameras, and
+polariscopes had each done
+their work, and the journey
+had not been taken in vain.
+In one point only we all
+differed, and this was about
+the direct ocular evidence,
+for each seemed to have
+seen a different corona, and
+the drawings of it were singularly
+unlike. Here are
+two (Figs. <a href="#ip_33">33</a> and <a href="#ip_34">34</a>) taken
+at this eclipse at the same
+time, and from neighboring
+stations, by two most experienced astronomers, Tacchini and
+Watson. No one could guess that they represented the same
+object, and a similar discrepancy was common.</p>
+
+<div id="ip_37" class="figright" style="max-width: 17em;">
+  <img src="images/i_049.jpg" alt="" />
+  <div class="caption">FIG. 37.—ENLARGEMENT OF PART OF FIG. 38.</div></div>
+
+<p>Considering that these were trained experts, whose special
+task it was, in this case, to draw the corona, which therefore
+claimed their undivided attention, I hardly know a more striking
+instance of the fallibility of human testimony. The evidence of
+several observers, however, pointed to the fact that the light
+really was more nearly confined to the part next the sun than
+the year before, so that the corona had probably changed during
+that interval, and grown smaller, which was remarkable enough.
+The evidence of the polariscope, on the whole, showed it to be<span class="pagenum" id="Page_50">50</span>
+partly due to reflected sunlight, while the spectroscope in the
+hands of Professor Young confirmed the last year’s observation,
+that it was also, and largely, self-luminous. Finally, the photographs,
+taken at very distant stations, showed the same dark
+rifts in the same place, and thus brought confirmatory evidence
+that it was not a local phenomenon in our own atmosphere.
+A photograph of it, taken by Mr. Brothers in Sicily, is the
+subject of the annexed illustration (<a href="#ip_35">Fig. 35</a>), in which the very
+bright lights which, owing to “photographic irradiation,” seem
+to indent the moon, are chiefly due to the colored flames I have
+spoken of, which will be described later.</p>
+
+<p>It may be observed that the photographs taken in the next
+year (1871) were still more successful, and began to show still
+more of the structure, whose curious forms, resembling large
+petals, had already been figured by Liais. His drawing (<a href="#ip_36">Fig. 36</a>),
+made in 1857, was supposed to be rather a fanciful sketch
+than a trustworthy one; but, as it will be seen, the photograph
+goes far to justify it.</p>
+
+<p>Figures 37 and 38 are copies published by Mr. Ranyard of
+the excellent photographs obtained in 1871, which are perhaps
+as good as anything done since, though even these do not show
+the outer corona. The first is an enlargement of a small portion
+of the detail in the second. It is scarcely possible for wood-engraving
+to reproduce the delicate texture of the original.</p>
+
+<div id="ip_38" class="figcenter" style="max-width: 32em;">
+  <img src="images/i_051.jpg" alt="" />
+  <div class="caption"><p>FIG. 38.—FAC-SIMILE OF PHOTOGRAPH OF CORONA OF 1871.</p>
+
+<p>(ROYAL ASTRONOMICAL SOCIETY’S MEMOIRS.)</p></div></div>
+
+<p>The years brought round the eclipse of 1878, which was again
+in United States territory, the central track (as <a href="#ip_30">Fig. 30</a> has already
+shown) running directly over one of the loftiest mountains
+of the country, Pike’s Peak, in Colorado. Pike’s Peak, though
+over fourteen thousand feet high, is often ascended by pleasure
+tourists; but it is one thing to stay there for an hour or
+two, and another to take up one’s abode there and get acclimated,—for
+to do the latter we must first pass through the
+horrors (not too strong a word) of mountain-sickness. This<span class="pagenum" id="Page_53">53</span>
+reaches its height usually on the second or third day, and is
+something like violent sea-sickness, complicated with the sensations
+a mouse may be supposed to have under the bell of an air-pump.
+After a week the strong begin to get over it, but none
+but the very robust should take its chances, as we did, without
+preparation; for on the night before the eclipse the life of one
+of our little party was pronounced in danger, and he was carried
+down in a litter to a cabin at an altitude of about ten thousand
+feet, where he recovered so speedily as to be able to do good service
+on the following day. The summit of the “Peak” is covered
+with great angular bowlders of splintered granite, among
+which we laid logs brought up for firewood, and on these, sacks
+of damp hay, then stretching a little tent over all and tying it
+down with wire to the rocks, we were fain to turn in under
+damp blankets, and to lie awake with incessant headache, drawing
+long, struggling breaths in the vain attempt to get air, and
+wondering how long the tent would last, as the canvas flapped
+and roared with a noise like that of a loose sail in a gale at sea,
+with occasional intervals of a dead silence, usually followed by
+a gust that shoved against the tent with the push of a solid
+body, and if a sleepers shoulders touched the canvas, shouldered
+him over in his bed. The stout canvas held, but the
+snow entered with the wind and lay in a deep drift on the pillow,
+when I woke after a brief sleep toward morning, and, looking
+out on the gray dawn, found that the snow had turned to
+hail, which was rattling sharply on the rocks with an accompaniment
+of thunder, which seemed to roll from all parts of the
+horizon. The snow lay thick, and the sheets of hail were like
+a wall, shutting out the sight of everything a few rods off, and
+this was in July! I thought of my December station in sunny
+Andalusia.</p>
+
+<div id="ip_39" class="figcenter clear" style="max-width: 25em;">
+  <img src="images/i_054.jpg" alt="" />
+  <div class="caption">FIG. 39.—“SPECTRES.”</div></div>
+
+<p>Hail, rain, sleet, snow, fog, and every form of bad weather
+continued for a week on the summit, while it was almost always<span class="pagenum" id="Page_54">54</span>
+clear below. It was often a remarkable sight to go to the edge
+and look down. The expanse of “the plains,” which stretched
+eastward to a horizon line over a hundred miles distant, would
+be in bright sunshine beneath, while the hail was all around and
+above us; and the light coming <em>up</em> instead of down gave singular
+effects when the clouds parted below, the plains seeming
+at such times to be opalescent with luminous yellow and green,
+as though the lower world were translucent, and the sun were
+beneath it and shining up through. <a href="#ip_39">Fig. 39</a> is a picture of
+three of us on the mountain-top, who saw a rarer spectacle;
+for directly opposite the setting sun, and on the mist over the<span class="pagenum" id="Page_55">55</span>
+gulf beyond us, was a bright ring, in whose centre were three
+phantom images of our three selves, which moved as we moved,
+and then faded as the sun sank. It was “the spectre of the
+Brocken.” These ghostly presentments were tolerably defined,
+as in the sketch, but did not seem to be gigantic, as some have
+described them. We rather thought them close at hand; but
+before we could determine, the vision faded.</p>
+
+<p>The clouds, to our good fortune, rolled away on the 29th;
+and a number of pleasure-seekers, who came up to view the
+eclipse and the unwonted bright sunshine, made a scene which
+it was hard to identify with the usual one. This time my business
+was to draw the corona; and the extreme altitude and the
+clearness of the air, with perhaps some greater extension than
+usual in the object itself, enabled it to be followed to an unprecedented
+distance. During totality the sun was surrounded by
+a narrow ring—hardly more than a line—of vivid light, presenting
+no structure to the naked eye (but a remarkable one in
+the telescope); and this faded with great suddenness into a circular
+nebulous luminosity between two and three diameters of
+the sun wide, but without such marked plumes, or filaments, as
+I had seen in 1869. The most extraordinary thing, however,
+was a beam of light, inclined at an angle of about forty-five
+degrees, about as wide as the sun, and extending to the distance
+of nearly six of its diameters on one side and over twelve on the
+other; on one side alone, that is, to the amazing distance of over
+ten million miles from its body. Substantially the same observation
+was made, as it appeared later, by Professor Newcomb,
+at a lower level. The direction, when more carefully measured,
+it was interesting to note, coincided closely with that of the
+Zodiacal light, and a faint central rib added to its resemblance
+to that body. It is noteworthy, in illustration of what has
+already been said as to the conflict of ocular testimony, that
+though I, with the great majority of observers below, saw only<span class="pagenum" id="Page_56">56</span>
+this beam, two witnesses whose evidence is unimpeachable, Professors
+Young and Abbe, saw a pale beam at right angles to it;
+and that one observer did not see the beam in question at all.
+<a href="#ip_40">Fig. 40</a> is a sketch made from my own, but necessarily on a
+scale which can show only its general features.</p>
+
+<p>With the telescope, the whole of the bright inner light close
+to the sun was found to be made up of filaments, more definite
+even than those described in a previous chapter as seen in sun-spots,
+and bristling in all directions from the edge; not concealing
+each other, as we might expect such things to do, upon a
+sphere, but fringing the sun’s edge in definite outline, as though
+it were really but a disk.</p>
+
+<div id="ip_40" class="figcenter" style="max-width: 33em;">
+  <img src="images/i_057.jpg" alt="" />
+  <div class="caption">FIG. 40.—OUTER CORONA OF 1878. (U. S. NAVAL OBSERVATORY.)</div></div>
+
+<p>Those who were at leisure to watch the coming shadow of
+the moon described its curved outline as distinctly visible on
+the plains. “A rounded ball of darkness with an orange-yellow
+border,” one called it. Those, again, who looked down on the
+bright clouds below say the shadow was preceded by a yellow
+fringe, casting a bright light over the clouds and passing into
+orange, pink, rose-red, and dark-red, in about twenty seconds.
+This beautiful effect was noticed by nearly all the amateur
+observers present, who had their attention at liberty, and was
+generally unseen by the professional ones, who were shut up
+in dark tents with photometers, or engaged otherwise than in
+admiring the glory of the spectacle as a spectacle merely. This
+strange light, forming a band of color about the shadow as seen
+from above, must have really covered ten miles or more in
+width, and have occupied a considerable fraction of a minute
+in passing over the heads of those below, to whom it probably
+constituted that lurid light on their landscape I have spoken
+of as so peculiar and “unnatural.” It seems to be due to the
+colored flames round the sun, which shine out when its brighter
+light is extinguished. I should add that on the summit of Pike’s
+Peak the corona did not entirely disappear at the instant the sun<span class="pagenum" id="Page_59">59</span>
+broke forth again, but that its outlying portions first went and
+then its brighter and inner ones, till our eager gaze, trying to
+follow it as long as possible, only after the
+lapse of some minutes saw the last of the
+wonderful thing disappear and “fade into
+the light of common day.”</p>
+
+<div id="ip_41" class="figleft" style="max-width: 9em;">
+  <img src="images/i_059.png" alt="" />
+  <div class="caption">FIG. 41.—SPECTROMETER SLIT
+AND SOLAR IMAGE. (FROM
+“THE SUN,” BY YOUNG.)</div></div>
+
+<p>There have been other eclipses since;
+but, in spite of all, our knowledge of the
+corona remains very incomplete, and if the
+most learned in such matters were asked
+what it was, he could probably answer truthfully, “I don’t
+know.”</p>
+
+<div id="ip_42" class="figright" style="max-width: 14em;">
+  <img src="images/i_059b.png" alt="" />
+  <div class="caption"><p>FIG. 42.—SLIT AND PROMINENCES.</p>
+
+<p>(“THE SUN,” BY YOUNG.)</p></div></div>
+
+<p>This will not be wondered at when it is considered that as
+total eclipses come, about every other year, and continue, one
+with another, hardly three minutes, an astronomer who should
+devote thirty years exclusively
+to the subject, never missing an
+eclipse in whatever quarter of
+the globe it occurred, would in
+that time have secured, in all,
+something like three-quarters of
+an hour for observation. Accordingly,
+what we know best
+about the corona is how it looks,
+what it <em>is</em> being still largely
+conjecture; and it is for this
+reason that I have thought the
+space devoted to it would be best used by giving the unscientific
+reader some idea of the visible phenomena as they present
+themselves to an eyewitness. Treatises like Lockyer’s “Solar
+Physics,” Proctor’s “The Sun,” Secchi’s “Le Soleil,” and Young’s
+“The Sun” (the latter is most recent), will give the reader who
+desires to learn more of the little that is known, the fuller information<span class="pagenum" id="Page_60">60</span>
+which this is not the place for; but it may be said very
+briefly that it is certain that the corona is at times of enormous
+extent (the whole length of the longer beam seen on Pike’s Peak
+must have been over fourteen million miles), that it almost certainly
+changes in its shape and dimensions from year to year
+(possibly much oftener, but this we cannot yet know), and that
+it shines partly by its own and partly by reflected light. When
+we come to ask whether it is a gas or not, the evidence is conflicting.
+The appearance of the green coronal line, and other
+testimony we have not alluded to, would make it seem almost
+certain that there must be a gas here of extreme tenuity, reaching
+the height of some hundred thousand miles, at the least;
+while yet the fact that such light bodies as comets have been
+known to pass through it, close to the sun, without suffering any
+visible retardation, such as would come even from a gas far
+lighter than hydrogen, appears to throw doubt on evidence
+otherwise strong. It is possible to conceive of the corona, and
+especially of the outer portion, as very largely made up of
+minute particles such as form the scattered dust of meteoric
+trains, and this seems to be the most probable constitution of its
+outlying parts. It is even possible to conceive that it is in some
+degree a subjective phenomenon, caused, as Professor Hastings
+has suggested, by diffraction upon the edge of the moon,—the
+moon, that is, not merely serving as a screen to the sun to reveal
+the corona, but partly <em>making</em> the corona by diffracting the light,
+somewhat as we see that the edge of any very distant object
+screening the sun is gilded by its beams. This effect may be
+seen when the sun rises or sets unusually clear, for objects on
+the horizon partly hiding it are then fringed for a moment with
+a line of light,—an appearance which has not escaped Shakspeare,
+where he <span class="locked">says,—</span></p>
+
+<p><span class="pagenum" id="Page_61">61</span></p>
+
+<div class="poetry-container">
+<div class="poetry">
+  <div class="stanza">
+    <div class="verse indentq">“But when from under this terrestrial ball</div>
+    <div class="verse indent0">He fires the tall tops of the eastern pines.”</div>
+  </div>
+</div>
+</div>
+
+<p>Still, in admitting the possibility of some such contributory
+effect on the part of the moon, we must not, of course, be understood
+as meaning that the corona as a whole does not have a
+real existence, quite independent of the changes which the presence
+of the moon may bring; and in leaving the wonderful
+thing we must remember that it is, after all, a reality, and not
+a phantasm.</p>
+
+<div id="ip_43" class="figcenter" style="max-width: 34em;">
+  <img src="images/i_062.jpg" alt="" />
+  <div class="caption">FIG. 43.—TACCHINI’S CHROMOSPHERIC CLOUDS. (“MEMORIE DEGLI SPETTROSCOPISTI ITALIANI.”)</div></div>
+
+<div id="ip_44" class="figcenter" style="max-width: 34em;">
+  <img src="images/i_062b.jpg" alt="" />
+  <div class="caption">FIG. 44.—TACCHINI’S CHROMOSPHERIC CLOUDS. (“MEMORIE DEGLI SPETTROSCOPISTI ITALIANI.”)</div></div>
+
+<p>I have already described how, at the eclipse of 1870, I (with
+others) saw within the corona what seemed like rose and scarlet-colored
+mountains rising from the sun’s edge, an appearance
+which had first been particularly studied in the eclipse of 1868,
+two years before, and which, it might be added, Messrs. Lockyer
+and Janssen had succeeded in observing without an eclipse by
+the spectroscope. Besides the corona, it may be said, then, that
+the sun is surrounded by a thin envelope, rising here and there
+into prominences of a rose and scarlet color, invisible in the telescope,
+except at a total eclipse, but always visible through the
+spectroscope. It is within and quite distinct from the corona,
+and is usually called the “chromosphere,” being a sort of sphere
+of colored fire surrounding the sun, but which we can usually
+see only on the edge. “The appearance,” says Young, “is as
+if countless jets of heated gas were issuing through vents and
+spiracles over the whole surface, thus clothing it with flame,
+which heaves and tosses like the blaze of a conflagration.” Out
+of this, then, somewhat like greater waves or larger swellings of
+the colored fires, rise the prominences, whose place, close to the
+sun’s edge, has been indicated in many of the drawings and
+photographs just given of the corona, on whose background they
+are seen during eclipses; but as they can be studied at our
+leisure with the spectroscope, we have reserved a more particular
+description of them till now. They are at all times directly before
+us, as well as the corona; but while both are yet invisible
+from the overpowering brightness of the sunlight reflected from<span class="pagenum" id="Page_62">62</span>
+the earth’s atmosphere in front of them, these red flames are so
+far brighter than the coronal background, that if we could only
+weaken this “glare” a little, they at least might become visible,
+even if the corona were not. The difficulty is evidently to find
+some contrivance which will weaken the “glare” without enfeebling
+the prominences too; and this the spectroscope does by
+diffusing the white sunlight, while it lets the color pass nearly
+unimpaired. For the full understanding of its action the reader<span class="pagenum" id="Page_63">63</span>
+must be referred to such works as those on the sun already mentioned;
+but a general idea of it may be gathered, if we reflect
+that white light is composed of every possible variety of colors,
+and that the spectroscope, which consists essentially of a prism
+behind a very narrow slit through which the light enters, lets
+any single color pass freely, without weakening it or altering it
+in anything but its direction, but gives a different direction to
+each, and hence sorts out the tints, distributing them side by
+side, every one in its own place, upon the long colored band
+called the spectrum. If this distribution has spread the colors
+along a space a thousand times as wide as the original beam, the
+average light must be just so much weaker than the white light
+was, because this originally consisted of a thousand (let us say a
+thousand, but it is really an infinite number) mingled tints of
+blue, green, yellow, orange, and red, which have now been thus
+distributed. If, however, we look through the prism at a rose-leaf,
+and it has no blue, green, yellow, or orange in it, and
+nothing but pure red, as each single color passes unchanged,
+this red will, according to what has been said, be as bright after
+it has passed as before. All depends, then, on the fact that these
+prominences do consist mainly of light of one color, like the
+rose-leaf, so that this monochromatic light will be seen through
+the spectroscope just as it is, while the luminous veil of glaring
+white before it will seem to be brushed away.</p>
+
+<p>If a large telescope be directed toward the sun, the glass at
+the farther end will, if we remove the eye-piece, form a little
+picture of the sun, as a picture is formed in a camera-obscura;
+and now, if we also fasten the spectroscope to this eye-end, where
+the observer’s head would be were he looking through, the edge
+of the solar image may be made to fall just <em>off</em> the slit, so that
+only the light from the prominences (and the white glare about
+them) shall pass in. To see this more clearly, let us turn our
+backs to the sun and the telescope, and look at the place where<span class="pagenum" id="Page_64">64</span>
+the image falls by the spectroscope slit, which in <a href="#ip_41">Fig. 41</a> is
+drawn of its full size. This is a brass plate, having a minute
+rectangular window, the “slit,” in it. The width of this slit is
+regulated by a screw, and any rays falling into the narrow aperture
+pass through the prism within, and finally fall on the observer’s
+eye, but not till they have been sorted by the prism in
+the manner described. Formed on the brass plate, just as it
+would be formed on a sheet of paper, or anything else held in
+the focus, we see the bright solar image, a circle of light perhaps
+an inch and a half in diameter,—a miniature of the sun with its
+spots. The whole of the sun (the photosphere) then is hidden
+to an observer who is looking up through the slit from the other
+side, for, as the sun’s edge does not quite touch the slit, none of
+its rays can enter it; but if there be also the image here of a
+prominence, projecting beyond the edge, and really overhanging
+the slit (though to us invisible on account of the glare about it),
+these rays will fall into the slit and pass down to the prism,
+which will dispose of it in the way already stated.</p>
+
+<div id="ip_45" class="figcenter" style="max-width: 22em;">
+  <img src="images/i_064.jpg" alt="" />
+  <div class="caption">FIG. 45.—VOGEL’S CHROMOSPHERIC FORMS. (“BEOBACHTUNGEN,” DR. H. C. VOGEL.)</div></div>
+
+<p>And now let us get to the other side, and, looking up through
+the prism with the aid of a magnifying-glass, see what it has<span class="pagenum" id="Page_65">65</span>
+done for us (<a href="#ip_42">Fig. 42</a>). The large rectangular opening here is
+the same as the small one which was visible from the outside,
+only that it is now magnified, and what was before invisible is
+seen; the edge of the sun itself is just hidden, but the scarlet
+flames of the chromosphere have become visible, with a cloudy
+prominence rising above them. The “flames” are flame-like
+only in form, for their light is probably due not to any combustion,
+but to the glow of intensely heated matter; and as its light
+is not quite pure red, we can, by going to another part of the
+spectrum, see the same thing repeated in orange, the effect being
+as though we had a number of long narrow windows, some
+glazed with red, some with orange, and some with other colors,
+through which we could look out at the same clouds. I have
+looked at these prominences often in this way; but I prefer, in
+the reader’s interest, to borrow from the description by Professor
+Young, who has made these most interesting and wonderful
+forms a special study.</p>
+
+<p>Let us premise that the depth of the crimson shell out of
+which they rise is usually less than five thousand miles, and
+that though the prominences vary greatly, the majority reach
+a height of nearly twenty thousand miles, while in exceptional
+cases this is immensely exceeded. Professor Young has seen
+one which grew to a height of three hundred and fifty thousand
+miles in an hour and a half, and in half an hour more had faded
+away.</p>
+
+<p>These forms fall into two main classes,—that of the quiet and
+cloud-like, and that of the eruptive,—the first being almost exactly
+in form like the clouds of our own sky, sometimes appearing
+to lie on the limb of the sun like a bank of clouds on the
+horizon, sometimes floating entirely free; while sometimes “the
+whole under surface is fringed with down-hanging filaments,
+which remind one of a summer shower hanging from a heavy
+thunder-cloud.”</p>
+
+<p><span class="pagenum" id="Page_66">66</span></p>
+
+<p>Here are some of the typical forms of the quieter <span class="locked">ones:—</span></p>
+
+<p><a href="#ip_43">Fig. 43</a>, by Tacchini, the Director of the Roman Observatory,
+represents an ordinary prominence, or cloud-group in the
+chromosphere, whose height is about twenty-five thousand miles.
+The little spires of flame which rise, thick as grass-blades, everywhere
+from the surface, are seen on its right and left.</p>
+
+<div id="ip_46" class="figcenter" style="max-width: 30em;">
+  <img src="images/i_066.jpg" alt="" />
+  <div class="caption">FIG. 46.—TACCHINI’S CHROMOSPHERIC FORMS. (“MEMORIE DEGLI SPETTROSCOPISTI
+ITALIANI.”)</div></div>
+
+<p><a href="#ip_44">Fig. 44</a> (Tacchini) is one where the agitation is greater and
+the “filamentary” type is more marked. Besides the curiously
+thread-like forms (so suggestive of what we have already seen
+in the photosphere), we have here what looks like an extended
+cloudy mass, drawn out by a horizontally moving wind.</p>
+
+<p><a href="#ip_45">Fig. 45</a> (by Vogel, at Bothkamp) represents another of these
+numerous types.</p>
+
+<p>The extraordinary <a href="#ip_46">Fig. 46</a> is from another drawing, by Tacchini,
+of a protuberance seen in 1871 (a time of great solar
+disturbance), and it belongs to the more energetic of its class.</p>
+
+<p><span class="pagenum" id="Page_67">67</span></p>
+
+<div id="ip_47" class="figcenter" style="max-width: 27em;">
+  <img src="images/i_067.jpg" alt="" />
+  <div class="caption">FIG. 47.—ERUPTIVE PROMINENCES. (“THE SUN,” BY YOUNG.)</div></div>
+
+<p>This fantastic cloud-shape, “if shape it might be called that
+shape had none,” looking like some nightmare vision, was about
+fifty thousand miles long and sixty thousand high above the
+surface. The reader will notice also the fiery rain, like the
+drops from a falling rocket, and may add to it all, in imagination,
+the actual color, which is of a deep scarlet.</p>
+
+<p>It may add to the-interest such things excite, to know that
+they have some mysterious connection with a terrestrial phenomenon,—the
+aurora,—for the northern lights have been<span class="pagenum" id="Page_68">68</span>
+again and again noticed to dance in company with these solar
+displays.</p>
+
+<p>The eruptive prominences are very different in appearance,
+as will be seen by the next illustration, for which we are indebted
+to Professor Young.</p>
+
+<p>In <a href="#ip_47">Fig. 47</a> we have a group of most interesting views by him
+(drawn here on the common scale of seventy-five thousand miles
+to an inch), illustrating the more eruptive types, of which we
+will let him speak directly. The first shows a case of the vertical
+filaments, like those rocket-drops we saw just, now in Tacchini’s
+drawing, but here more marked; while the second (on
+the left side) is a cyclone-form, where the twisted stems suggest
+what we have seen before in the “bridges” of sun-spots,
+and below this is another example of filamentary forms.</p>
+
+<p>The upper one, on the right, is the view of a cloud prominence
+as it appeared at <em>half-past twelve</em> o’clock, on Sept. 7,
+1871. Below it is the same prominence at <em>one</em> o’clock (half an
+hour later), when it has been shattered by some inconceivable
+explosion, blowing it into fragments, and driving the hydrogen
+to a height of two hundred thousand miles. The lowest figure
+on the right shows another case where inclined jets (of hydrogen)
+were seen to rise to a height of fifty thousand miles.</p>
+
+<p>Professor Young says of <span class="locked">these:—</span></p>
+
+<div class="blockquot">
+
+<p>“Their form and appearance change with great rapidity, so that the
+motion can almost be seen with the eye. Sometimes they consist of
+pointed rays, diverging in all directions, like hedgehog-spines. Sometimes
+they look like flames; sometimes like sheaves of grain; sometimes
+like whirling water-spouts, capped with a great cloud; occasionally they
+present most exactly the appearance of jets of liquid fire, rising and falling
+in graceful parabolas; frequently they carry on their edges spirals
+like the volutes of an Ionic column; and continually they detach filaments
+which rise to a great elevation, gradually expanding and growing
+fainter as they ascend, until the eye loses them. There is no end to the
+number of curious and interesting appearances which they exhibit under<span class="pagenum" id="Page_69">69</span>
+varying circumstances. The velocity of the motions often exceeds a
+hundred miles a second, and sometimes, though very rarely, reaches
+two hundred miles.”</p>
+</div>
+
+<p>In the case of the particular phenomenon recorded by Professor
+Young in the last illustration, Mr. Proctor, however, has
+calculated that the initial velocity probably exceeded five hundred
+miles a second, which, except for the resistance experienced
+by the sun’s own atmosphere, would have hurled the ejected
+matter into space entirely clear of the sun’s power to recall it,
+so that it would never return.</p>
+
+<p>It adds to our interest in these flames to know that they at
+least are connected with that up-rush of heated matter from the
+sun’s interior, forming a part of the circulation which maintains
+both the temperature of its surface and that radiation on which
+all terrestrial life depends. The flames, indeed, add of themselves
+little to the heat the sun sends us, but they are in this
+way the outward and visible signs of a constant process within,
+by which we live; and so far they seem to have a more immediate
+interest to us, though invisible, than the corona which surrounds
+them. But we must remember when we lift our eyes to
+the sun that this latter wonder is really there, whether man sees
+it or not, and that the cause of its existence is still unknown.</p>
+
+<p>We ask for its “object” perhaps with an unconscious assumption
+that the whole must have been in some way provided to
+subserve <em>our</em> wants; but there is not as yet the slightest evidence
+connecting its existence with any human need or purpose, and
+as yet we have no knowledge that, in this sense, it exists to any
+“end” at all. “As the thought of man is widened with the
+process of the suns,” let us hope that we shall one day know
+more.</p>
+
+<hr />
+
+<div id="toclink_70" class="chapter">
+<p><span class="pagenum" id="Page_70">70</span></p>
+
+<h2 class="nobreak" id="III">III.<br />
+
+<span class="subhead">THE SUN’S ENERGY.</span></h2>
+</div>
+
+<p class="drop-cap"><span class="smcap1">“It</span> is indeed,” says good Bishop Berkeley, “an opinion
+strangely prevailing amongst men that ... all sensible
+objects have an existence ... distinct from their being perceived
+by the understanding. But ... some truths there are,
+so near and obvious to the mind, that a man need only open
+his eyes to see them. Such I take this important one to be,
+namely, that all the choir of heaven and furniture of the earth—in
+a word, all those bodies which compose the mighty frame of
+the world—have not any subsistence without a mind.”</p>
+
+<p>We are not going to take the reader along “the high priori
+road” of metaphysics, but only to speak of certain accepted
+conclusions of modern experimental physics, which do not themselves,
+indeed, justify all of Berkeley’s language, but to which
+these words of the author of “A New Theory of Vision” seem
+to be a not unfit prelude.</p>
+
+<p>When we see a rose-leaf, we see with it what we call a color,
+and we are apt to think it is in the rose. But the color is in <em>us</em>,
+for it is a sensation which something coming from the sun excites
+in the eye; so that if the rose-leaf were still there, there
+would be no color unless there were an eye to receive and a
+brain to interpret the sensation. Every color that is lovely in
+the rainbow or the flower, every hue that is vivid in a ribbon or
+sombre in the grave harmonies of some old Persian rug, the
+metallic lustre of the humming-bird or the sober imperial yellow<span class="pagenum" id="Page_71">71</span>
+of precious china,—all these have no existence as color apart
+from the seeing eye, and all have their fount and origin in the
+sun itself.</p>
+
+<p>“Color” and “light,” then, are not, properly speaking, external
+things, but names given to the sensations caused by an
+uncomprehended something radiated from the sun, when this
+falls on our eyes. If this very same something falls on our face,
+it produces another kind of sensation, which we call “heat,” or
+if it falls on a thermometer it makes it rise; while if it rests long
+on the face it will produce yet another effect, “chemical action,”
+for it will <em>tan</em> the cheek, producing a chemical change there;
+or it will do the like work more promptly if it meet a photographic
+plate. If we bear in mind that it is the identically same
+thing (whatever that is) which produces all these diverse effects,
+we see, some of us perhaps for the first time, that “color,”
+“light,” “radiant heat,” “actinism,” etc., are only names given
+to the diverse effects of some thing, not things themselves; so
+that, for instance, all the splendor of color in the visible world
+<em>exists only in the eye that sees it</em>. The reader must not suppose
+that he is here being asked to entertain any metaphysical subtlety.
+We are considering a fact almost universally accepted
+within the last few years by physicists, who now generally
+admit the existence of a something coming from the sun, which
+is not itself light, heat, or chemical action, but of which these
+are effects. When we give this unknown thing a name, we call
+it “radiant energy.”</p>
+
+<p>How it crosses the void of space we cannot be properly said
+to know, but all the phenomena lead us to think it is in the
+form of motion in some medium,—somewhat (to use an imperfect
+analogy) like the transmission through the air of the vibrations
+which will cause sound when they reach an ear. This, at
+any rate, is certain, that there is an action of some sort incessantly
+going on between us and the sun, which enables us to<span class="pagenum" id="Page_72">72</span>
+experience the effects of light and heat. We assume it to be a
+particular mode of vibration; but whatever it is, it is repeated
+with incomprehensible rapidity. Experiments recently made by
+the writer show that the <em>slower</em> heat vibrations which reach us
+from the sun succeed each other nearly 100,000,000,000,000
+times in a single second, while those which make us see, have
+long been known to be more rapid still. These pass outward
+from the sun in every direction, in ever-widening spheres; and
+in them, so far as we know, lies the potency of life for the
+planet upon whose surface they fall.</p>
+
+<p>Did the reader ever consider that next to the mystery of
+gravitation, which draws all things on the earth’s surface down,
+comes that mystery—not seen to be one because so familiar—of
+the occult force in the sunbeams which lifts things <em>up</em>? The
+incomprehensible energy of the sunbeam brought the carbon out
+of the air, put it together in the weed or the plant, and lifted
+each tree-trunk above the soil. The soil did not lift it, any
+more than the soil in Broadway lifted the spire of Trinity. Men
+brought stones there in wagons to build the church, and the sun
+brought the materials in its own way, and built up alike the
+slender shaft that sustains the grass blade and the column of
+the pine. If the tree or the spire fell, it would require a certain
+amount of work of men or horses or engines to set it up again.
+So much actual work, at least, the sun did in the original building;
+and if we consider the number of trees in the forest, we see
+that this alone is something great. But besides this, the sun
+locked up in each tree a store of energy thousands of times
+greater than that which was spent in merely lifting the trunk
+from the ground, as we may see by unlocking it again, when we
+burn the tree under the boiler of an engine; for it will develop
+a power equal to the lifting of thousands of its kind, if we
+choose to employ it in this way. This is so true, that the tree
+may fall, and turn to coal in the soil, and still keep this energy<span class="pagenum" id="Page_73">73</span>
+imprisoned in it,—keep it for millions of years, till the black
+lump under the furnace gives out, in the whirling spindles of
+the factory or the turning wheel of the steamboat, the energy
+gathered in the sunshine of the primeval world.</p>
+
+<p>The most active rays in building up plant-life are said to be
+the yellow and orange, though Nature’s fondness for green
+everywhere is probably justified by some special utility. At
+any rate, the action of these solar rays is to decompose the
+products of combustion, to set free the oxygen, and to fix the
+carbon in the plant. Perhaps these words do not convey a
+definite meaning to the reader, but it is to be hoped they will,
+for the statement they imply is wonderful enough. Swift’s
+philosopher at Laputa, who had a project for extracting sunbeams
+out of cucumbers, was wiser than his author knew; for
+cucumbers, like other vegetables, are now found to be really in
+large part put together by sunbeams, and sunbeams, or what is
+scarcely distinguishable from such, could with our present scientific
+knowledge be extracted from cucumbers again, only the
+process would be too expensive to pay. The sunbeam, however,
+does what our wisest chemistry cannot do: it takes the
+burned out ashes and makes them anew into green wood; it
+takes the close and breathed out air, and makes it sweet and fit
+to breathe by means of the plant, whose food is the same as our
+poison. With the aid of sunlight a lily would thrive on the
+deadly atmosphere of the “black hole of Calcutta;” for this
+bane to us, we repeat, is vital air to the plant, which breathes
+it in through all its pores, bringing it into contact with the chlorophyl,
+its green blood, which is to it what the red blood is to
+us; doing almost everything, however, by means of the sun
+ray, for if this be lacking, the oxygen is no longer set free or
+the carbon retained, and the plant dies. This too brief statement
+must answer instead of a fuller description of how the
+sun’s energy builds up the vegetable world.</p>
+
+<p><span class="pagenum" id="Page_74">74</span></p>
+
+<p>But the ox, the sheep, and the lamb feed on the vegetable,
+and we in turn on them (and on vegetables too); so that,
+though we might eat our own meals in darkness and still live,
+the meals themselves are provided literally at the sun’s expense,
+virtue having gone out of him to furnish each morsel we put in
+our mouths. But while he thus prepares the material for our
+own bodies, and while it is plain that without him we could not
+exist any more than the plant, the processes by which he acts
+grow more intricate and more obscure in our own higher organism,
+so that science as yet only half guesses how the sun makes
+us. But the making is done in some way by the sun, and so
+almost exclusively is every process of life.</p>
+
+<p>It is not generally understood, I think, how literally true this
+is of every object in the organic world. In a subsequent illustration
+we shall see a newspaper being printed by power directly
+and visibly derived from the sunbeam. But all the power derived
+from coal, and all the power derived from human muscles,
+comes originally from the sun, in just as literal a sense; for the
+paper on which the reader’s eye rests was not only made primarily
+from material grown by the sun, but was stitched together
+by derived sun-power, and by this, also, each page was
+printed, so that the amount of this solar radiation expended for
+printing each chapter of this book could be stated with approximate
+accuracy in figures. To make even the reader’s hand
+which holds this page, or the eye which sees it, energy again
+went out from the sun; and in saying this I am to be understood
+in the plain and common meaning of the words.</p>
+
+<p>Did the reader ever happen to be in a great cotton-mill,
+where many hundreds of operatives watched many thousands
+of spindles? Nothing is visible to cause the multiplied movement,
+the engine being perhaps away in altogether another
+building. Wandering from room to room, where everything is
+in motion derived from some unseen source, he may be arrested<span class="pagenum" id="Page_75">75</span>
+in his walk by a sudden cessation of the hum and bustle,—at
+once on the floor below, and on that above, and all around him.
+The simultaneousness of this stoppage at points far apart when
+the steam is turned off, strikes one with a sense of the intimate
+dependence of every complex process going on upon some remote
+invisible motor. The cessation is not, however, absolutely
+instantaneous; for the great fly-wheel, in which a trifling part of
+the motor power is stored, makes one or two turns more, till the
+energy in this also is exhausted, and all is still. The coal-beds
+and the forests are to the sun what the fly-wheel is to the
+engine: all their power comes from him; they retain a little of
+it in store, but very little by comparison with the original; and
+were the change we have already spoken of to come over the
+sun’s circulation,—were the solar engine disconnected from us,—we
+could go on perhaps a short time at the cost of this store,
+but when this was over it would be over with us, and all would
+be still here too.</p>
+
+<p>Is there not a special interest for us in that New Astronomy
+which considers these things, and studies the sun, not only in
+the heavens as a star, but in its workings here, and so largely
+in its relations to man?</p>
+
+<div class="tb">* * * * *</div>
+
+<p>Since, then, we are the children of the sun, and our bodies a
+product of its rays, as much as the ephemeral insects that its
+heat hatches from the soil, it is a worthy problem to learn how
+things earthly depend upon this material ruler of our days. But
+although we know it does nearly all things done on the earth,
+and have learned a little of the way it builds up the plant, we
+know so little of the way it does many other things here that
+we are still often only able to connect the terrestrial effect with
+the solar cause by noting what events happen together. We are
+in this respect in the position of our forefathers, who had not yet
+learned the science of electricity, but who noted that when a<span class="pagenum" id="Page_76">76</span>
+flash of lightning came a clap of thunder followed, and concluded
+as justly as Franklin or Faraday could have done that
+there was a physical relation between them. Quite in this way,
+we who are in a like position with regard to the New Astronomy,
+which we hope will one day explain to us what is at
+present mysterious in our connection with the sun, can as yet
+often only infer that when certain phenomena there are followed
+or accompanied by others here, all are really connected as products
+of one cause, however dissimilar they may look, and however
+little we know what the real connection may be.</p>
+
+<p>There is no more common inquiry than as to the influence of
+sun-spots on the weather; but as we do not yet know the real
+nature of the connection, if there be any, we can only try to
+find out by assembling independent records of sun-spots and of
+the weather here, and noticing if any changes in the one are
+accompanied by changes in the other; to see, for instance, if
+when sun-spots are plenty the weather the world over is rainy
+or not, or to see if when an unusual disturbance breaks out in
+a sun-spot any terrestrial disturbance is simultaneously noted.</p>
+
+<div id="ip_48" class="figcenter" style="max-width: 26em;">
+  <img src="images/i_077.png" alt="" />
+  <div class="caption">FIG. 48.—SUN-SPOTS AND PRICE OF GRAIN. (FROM “OBSERVATIONS OF SOLAR SPOTS.”)</div></div>
+
+<p>When we remember how our lives depend on a certain circulation
+in the sun, of which the spots appear to be special examples,
+it is of interest not only to study the forms within them,
+as we have already been doing here, but to ask whether the
+spots themselves are present as much one year as another. The
+sun sometimes has numerous spots on it, and sometimes none at
+all; but it does not seem to have occurred to any one to see
+whether they had any regular period for coming or going, till
+Schwabe, a magistrate in a little German town, who happened
+to have a small telescope and a good deal of leisure, began for
+his own amusement to note their number every day. He commenced
+in 1826, and with German patience observed daily for
+forty years. He first found that the spots grew more numerous
+in 1830, when there was no single day without one; then the<span class="pagenum" id="Page_77">77</span>
+number declined very rapidly, till in 1833 they were about
+gone; then they increased in number again till 1838, then again
+declined; and so on, till it became evident that sun-spots do not
+come and go by chance, but run through a cycle of growth and
+disappearance, on the average about once in every eleven years.
+While amusing himself with his telescope, an important sequence
+in Nature had thus been added to our knowledge by the obscure
+Hofrath Schwabe, who indeed compares himself to Saul, going
+out to seek his father’s asses and finding a kingdom. Old records
+made before Schwabe’s time have since been hunted up, so
+that we have a fairly connected history of the sun’s surface for
+nearly a hundred and fifty years; and the years when spots will
+be plentiful or rare can now be often predicted from seeing<span class="pagenum" id="Page_78">78</span>
+what has been in the past. Thus I may venture to say that the
+spots, so frequent in 1885, will have probably nearly disappeared
+in 1888, and will be probably very plentiful in 1894. I do not
+know at all why this is likely to happen; I only know that it
+has repeatedly happened at corresponding periods in the past.</p>
+
+<p>“Now,” it may be asked, “have these things any connection
+with weather changes, and is it of any practical advantage to
+know if they have?”</p>
+
+<p>Would it be, it may be answered, of any practical interest to
+a merchant in bread-stuffs to have private information of a reliable
+character that crops the world over would be fine in 1888
+and fail in 1894? The exclusive possession of such knowledge
+might plainly bring “wealth beyond the dreams of avarice” to
+the user; or, to ascend from the lower ground of personal
+interest to the higher aims of philanthropy and science, could
+we predict the harvests, we should be armed with a knowledge
+that might provide against coming years of famine, and make
+life distinctly happier and easier to hundreds of millions of
+toilers on the earth’s surface.</p>
+
+<p>“But can we predict?” We certainly cannot till we have,
+at any rate, first shown that there is a connection between sun-spots
+and the weather. Since we know nothing of the ultimate
+causes involved, we can only at present, as I say, collect records
+of the changes there, and compare them with others of the
+changes here, to see if there is any significant coincidence.
+To avoid columns of figures, and yet to enable the reader
+to judge for himself in some degree of the evidence, I will
+give the results of some of these records represented graphically
+by curves, like those which he may perhaps remember
+to have seen used to show the fluctuations in the value of
+gold and grain, or of stocks in the stock-market. It is only
+fair to say that mathematicians used this method long before
+it was ever heard of by business men, and that the stockbrokers<span class="pagenum" id="Page_79">79</span>
+borrowed it from the astronomers, and not the astronomers
+from them.</p>
+
+<p>In <a href="#ip_48">Fig. 48</a>, from Carrington’s work, each horizontal space
+represents ten years of time, and the figures in the upper part
+represent the fluctuations of the sun-spot curve. In the middle
+curve, variations in vertical distances correspond to differences
+in the distance from the sun of the planet Jupiter, the possibility
+of whose influence on sun-spot periods can thus be examined.
+In the third and lowest, suggested by Sir William Herschel, the
+figures at the side are proportional to the price of wheat in the
+English market, rising when wheat ruled high, falling when it
+was cheap. In all three curves one-tenth of a horizontal spacing
+along the top or bottom corresponds to one year; and in this
+way we have at a glance the condensed result of observations
+and statistics for sixty years, which otherwise stated would fill
+volumes. The result is instructive in more ways than one.
+The variations of Jupiter’s distance certainly do present a striking
+coincidence with the changes in spot frequency, and this
+may indicate a real connection between the phenomena; but
+before we decide that it does so, we must remember that the
+number of cycles of change presented by the possible combination
+of planetary periods is all but infinite. Thus we might
+safely undertake, with study enough, to find a curve, depending
+solely on certain planetary configurations, which yet would
+represent with quite striking agreement for a time the rise and
+fall in any given railroad stock, the relative numbers of Democratic
+and Republican congressmen from year to year, or anything
+else with which the heavenly bodies have in reality as
+little to do. The third curve (meant by the price of wheat to
+test the possible influence of sun-spots on years of good or bad
+harvests) is not open to the last objection, but involves a fallacy
+of another kind. In fact the price of wheat depends on many
+things quite apart from the operations of Nature,—on wars and<span class="pagenum" id="Page_80">80</span>
+legislation, for instance; and here the great rise in the first
+years of the century is as clearly connected with the great continental
+wars of the first Napoleon, which shut up foreign ports,
+as the sudden fall about 1815, the year of Waterloo, is with the
+subsequent peace. Meanwhile an immense amount of labor has
+been spent in making tables of the weather, and of almost every
+conceivable earthly phenomenon which may be supposed to
+have a similar periodic character, with very doubtful success,
+nearly every one having brought out some result which might
+be plausible if it stood alone, but which is apt to be contradicted
+by the others. For instance, Mr. Stone, at the Cape of Good
+Hope, and Dr. Gould, in
+South America, consider
+that the observations taken
+at those places show a little
+diminution of the earth’s
+temperature (amounting to
+one or two degrees) at a
+sun-spot maximum. Mr.
+Chambers concludes, from
+twenty-eight years’ observations,
+that the hottest are those of most sun-spots. So each of
+these contradicts the other. Then we have Gelinck, who, from
+a study of numerous observations, concludes that all are wrong
+together, and that there is really no change in either way.</p>
+
+<div id="ip_49" class="figleft" style="max-width: 16em;">
+  <img src="images/i_080.png" alt="" />
+  <div class="caption">FIG. 49.—SUN-SPOT OF NOV. 16, 1882, AND EARTH.</div></div>
+
+<p>I might go on citing names with no better result. One
+observer tabulates observations of terrestrial temperature, or
+rain-fall, or barometer, or ozone; another, the visitations of
+Asiatic cholera; while still another (the late Professor Jevons)
+tabulates commercial crises with the serious attempt to find a
+connection between the sun-spots and business panics. Of
+making such cycles there is no end, and much study of them
+would be a weariness I will not inflict.</p>
+
+<p><span class="pagenum" id="Page_81">81</span></p>
+
+<div id="ip_50" class="figcenter clear" style="max-width: 34em;">
+  <img src="images/i_081.jpg" alt="" />
+  <div class="caption">FIG. 50.—GREENWICH RECORD OF DISTURBANCE OF MAGNETIC NEEDLE, NOV. 16 AND 17, 1882.</div></div>
+
+<p><span class="pagenum" id="Page_83">83</span></p>
+
+<p>Our own conclusion is, that from such investigations of
+terrestrial changes nothing is yet certainly known with regard
+to the influence of sun-spots on the weather. There is, however,
+quite another way; that is, to measure their effect at the origin
+in the sun itself. The sun-spot is cooler than the rest of the
+surface, and it might be thought that when there are many the
+sun would give less heat. As far as the spots themselves are
+concerned, this is so, but in a very small degree. I have been
+able to ascertain how much this deprivation of heat amounts to,
+and find it is a real but a most insignificant quantity, rising to
+about two-thirds of one degree Fahrenheit every eleven years.
+This, it will be remembered, is the direct effect of the spots
+considered merely as so many cool patches on the surface, and
+it does not imply that when there are most spots the sun will
+necessarily give less heat. In fact there may be a compensating
+action accompanying them which makes the radiation greater
+than when they are absent. I will not enter on a detailed
+explanation, but only say that in the best judgment I can form
+by a good deal of study and direct experiment, there is no
+certain evidence that the sun is hotter at one time than at
+another.</p>
+
+<p>If we investigate, however, the connection between spots
+and terrestrial magnetic disturbances, we shall find altogether
+more satisfactory testimony. This evidence is of all degrees of
+strength, from probability up to what may be called certainty,
+and it is always obtained, not by <i xml:lang="la" lang="la">a priori</i> reasoning, but by the
+comparison of independent observations of something which has
+happened on the sun and on the earth. We will first take an
+instance of what we consider the weakest degree of evidence
+(weak, that is, when any such single case is considered), and
+we do so by simply quoting textually three records which were
+made at nearly the same time in different parts of the world
+in 1882.</p>
+
+<p><span class="pagenum" id="Page_84">84</span></p>
+
+<p>A certain spot had been visible on the sun at intervals for
+some weeks; but when on the 16th of November a glimpse was
+caught of it after previous days of cloudy weather, the observer,
+it will be seen, is struck by the great activity going on in it,
+and, though familiar with such sights, describes this one as
+“magnificent.”</p>
+
+<p>1. From the daily record at the Allegheny Observatory, November
+16, <span class="locked">1882:—</span></p>
+
+<div class="blockquot">
+
+<p>“Very large spot on the sun; ... great variety of forms; inrush
+from S. E. to S. W.; tendency to cyclonic action at several points. The
+spot is apparently near its period of greatest activity. A magnificent
+sight.”</p>
+</div>
+
+<p>At the same time a sketch was commenced which was interrupted
+by the cloudy weather of this and following days. The
+outline of the main spot only is here given (<a href="#ip_49">Fig. 49</a>). Its area,
+as measured at Allegheny, was 2,200,000,000 square miles; at
+Greenwich its area, inclusive of some outlying portions, was
+estimated on the same day to be 2,600,000,000 square miles.
+The earth is shown of its relative size upon it, to give a proper
+idea of the scale.</p>
+
+<p>2. From the “New York Tribune” of November 18th (describing
+what took place in the night preceding the <span class="locked">17th):—</span></p>
+
+<div class="blockquot">
+
+<p class="center vspace"><span class="larger">AN ELECTRIC STORM.</span><br />
+TELEGRAPH WIRES GREATLY AFFECTED.<br />
+THE DISTURBANCE WIDE-SPREAD.</p>
+
+<p>... At the Mutual Union office the manager said, “Our wires are
+all running, but very slowly. There is often an intermission of from one
+to five minutes between the words of a sentence. The electric storm is
+general as far as our wires are concerned.”... The cable messages were
+also delayed, in some cases as much as an hour.</p>
+
+<p>The telephone service was practically useless during the day.</p>
+
+<p><span class="smcap">Washington</span>, <i>Nov. 17</i>.—A magnetic storm of more than usual
+intensity began here at an early hour this morning, and has continued<span class="pagenum" id="Page_85">85</span>
+with occasional interruptions during the day, seriously interfering with
+telegraphic communication.... As an experiment one of the wires of
+the Western Union Telegraph Company was worked between Washington
+and Baltimore this afternoon with the terrestrial current alone, the
+batteries having been entirely detached.</p>
+
+<p><span class="smcap">Chicago</span>, <i>Nov. 17</i>.—An electric storm of the greatest violence raged
+in all the territory to points beyond Omaha.... The switch-board here
+has been on fire a dozen times during the forenoon. At noon only a single
+wire out of fifteen between this city and New York was in operation.</p>
+</div>
+
+<p>And so on through a column.</p>
+
+<p>3. In <a href="#ip_50">Fig. 50</a> we give a portion of the automatic trace of the
+magnetic needles at Greenwich.<a id="FNanchor_3" href="#Footnote_3" class="fnanchor">3</a> These needles are mounted
+on massive piers in the cellars of the observatory, far removed
+from every visible source of disturbance, and each carries a
+small mirror, whence a spot of light is reflected upon a strip of
+photographic paper, kept continually rolling before it by clock-work.
+If the needle is still, the moving strip of paper will have
+a straight line on it, traced by the point of light, which is in this
+case motionless. If the needle swings to the right or left, the
+light-spot vibrates with it, and the line it traces becomes sinuous,
+or more and more sharply zigzagged as the needle shivers under
+the unknown forces which control it.</p>
+
+<div class="footnote">
+
+<p><a id="Footnote_3" href="#FNanchor_3" class="fnanchor">3</a> It appears here through the kindness of the Astronomer Royal. We regret to say
+that American observers are dependent on the courtesy of foreign ones in such matters,
+the United States having no observatory where such records of sun-spots and magnetic
+variation are systematically kept.</p>
+
+</div>
+
+<p>The upper part of <a href="#ip_50">Fig. 50</a> gives a little portion of this automatic
+trace on November 16th before the disturbance began, to
+show the ordinary daily record, which should be compared with
+the violent perturbation occurring simultaneously with the telegraphic
+disturbance in the United States. We may, for the
+reader’s convenience, remark that as the astronomical day begins
+twelve hours later than the civil day, the approximate Washington
+mean times, corresponding to the Greenwich hours after<span class="pagenum" id="Page_86">86</span>
+twelve, are found by adding one to the days and subtracting
+seventeen from the hours. Thus “November 16th, twenty-two
+hours” corresponds in the eastern United States nearly to five
+o’clock in the morning of November 17th.</p>
+
+<p>The Allegheny observer, it will be remembered, in his
+glimpse of the spot on November 16th, was struck with the
+great activity of the internal motions then going on in it. The
+Astronomer Royal states that a portion of the spot became
+detached on November 17th or 18th, and that several small
+spots which broke out in the immediate neighborhood were
+seen for the first time on the photographs taken November
+17th, twenty-two hours.</p>
+
+<p>“Are we to conclude from this,” it may be asked, “that what
+went on in the sun was the cause of the trouble on the telegraph
+wires?” I think we are not at all entitled to conclude so from
+this instance <em>alone</em>; but though in one such case, taken by itself,
+there is nothing conclusive, yet when such a degree of coincidence
+occurs again and again, the habitual observer of solar
+phenomena learns to look with some confidence for evidence of
+electrical disturbance here following certain kinds of disturbance
+there, and the weight of this part of the evidence is not to be
+sought so much in the strength of a single case, as in the
+multitude of such coincidences.</p>
+
+<p>We have, however, not only the means of comparing sun-spot
+<em>years</em> with years of terrestrial electric disturbance, but
+individual instances, particular <em>minutes</em> of sun-spot changes, with
+particular minutes of terrestrial change; and both comparisons
+are of the most convincing character.</p>
+
+<p>First, let us observe that the compass needle, in its regular
+and ordinary behavior, does not point constantly in any one direction
+through the day, but moves a very little one way in
+the morning, and back in the afternoon. This same movement,
+which can be noticed even in a good surveyor’s compass, is<span class="pagenum" id="Page_87">87</span>
+called the “diurnal oscillation,” and has long been known. It
+has been known, too, that its amount altered from one year to
+another; but since Schwabe’s observations it has been found that
+the changes in this variation and in the number of the spots went
+on together. The coincidences which we failed to note in the
+comparison of the spots with the prices of grain are here made
+out with convincing clearness, as the reader will see by a simple
+inspection of this chart (<a href="#ip_51">Fig. 51</a>, taken from Professor Young’s
+work), where the horizontal divisions still denote years, and the
+height of the continuous curve the relative number of spots,
+while the height of the dotted curve is the amount of the magnetic
+variation. Though we have given but a part of the curve,
+the presumption from the agreement in the forty years alone
+would be a strong one that the two effects, apparently so widely
+remote in their nature, are really due to a common cause.</p>
+
+<div id="ip_51" class="figcenter" style="max-width: 34em;">
+  <img src="images/i_087.png" alt="" />
+  <div class="caption">FIG. 51.—SUN-SPOTS AND MAGNETIC VARIATIONS.</div></div>
+
+<p>Here we have compared years with years; let us next compare
+minutes with minutes. Thus, to cite (from Mr. Proctor’s
+work) a well-known instance: On Sept. 1, 1869, at eighteen minutes
+past eleven, Mr. Carrington, an experienced solar observer,
+suddenly saw in the sun something brighter than the sun,—two
+patches of light, breaking out so instantly and so intensely<span class="pagenum" id="Page_88">88</span>
+that his first thought was that daylight was entering through
+a hole in the darkening screen he used. It was immediately,
+however, made certain that something unusual was occurring
+in the sun itself, across which the brilliant spots were moving,
+travelling thirty-five thousand miles in five minutes, at the end
+of which time (at twenty-three minutes past eleven) they disappeared
+from sight. By good fortune, another observer a few
+miles distant saw and independently described the same phenomenon;
+and as the minute had been noted, it was immediately
+afterward found that recording instruments registered a
+magnetic disturbance at the same time,—“at the very moment,”
+says Dr. Stewart, the director of the observatory at Kew.</p>
+
+<p>“By degrees,” says Sir John Herschel, “accounts began to
+pour in of ... great electro-magnetic disturbances in every
+part of the world.... At Washington and Philadelphia, in
+America, the telegraphic signal men received severe electric
+shocks. At Boston, in North America, a flame of fire followed
+the pen of Bain’s electric telegraph.” (Such electric disturbances,
+it may be mentioned, are called “electric storms,” though
+when they occur the weather may be perfectly serene to the
+eye. They are shown also by rapid vibrations of the magnetic
+needle, like those we have illustrated.)</p>
+
+<p>On Aug. 3, 1872, Professor Young, who was observing at
+Sherman in the Rocky Mountains, saw three notable paroxysms
+in the sun’s chromosphere, jets of luminous matter of intense
+brilliance being projected at 8h. 45m., 10h. 30m., and 11h. 50m.
+of the local time. “At dinner,” he says, “the photographer of
+the party, who was making our magnetic observations, told me,
+before knowing anything about what I had been observing, that
+he had been obliged to give up work, his magnet having swung
+clear off the limb.” Similar phenomena were observed August
+5th. Professor Young wrote to England, and received from
+Greenwich and Stonyhurst copies of the automatic record,<span class="pagenum" id="Page_89">89</span>
+which he gives, and which we give in <a href="#ip_52">Fig. 52</a>. After allowing
+for difference of longitude, the reader who will take the pains
+to compare them may see for himself that both show a jump of
+the needles in the cellars at Greenwich at the same <em>minute</em> in
+each of the four cases of outburst in the Rocky Mountains.</p>
+
+<div id="ip_52" class="figcenter" style="max-width: 23em;">
+  <img src="images/i_089.jpg" alt="" />
+  <div class="caption">FIG. 52.—GREENWICH MAGNETIC OBSERVATIONS, AUG. 3 AND 5, 1872.</div></div>
+
+<p>While we admit that the evidence in any single case is rarely
+so conclusive as in these; while we agree that the spot is not so
+much the cause of the change as the index of some other solar
+action which does cause it; and while we fully concede our
+present ignorance of the nature of this cause,—we cannot refuse
+to accept the cumulative evidence, of which a little has
+been submitted.</p>
+
+<p>It is only in rare cases that we can feel quite sure; and yet,
+in regard even to one of the more common and less conclusive
+ones, we may at least feel warranted in saying that if the reader
+forfeited a business engagement or missed an invitation to dinner
+through the failure of the telegraph or telephone on such an<span class="pagenum" id="Page_90">90</span>
+occasion as that of the 17th of November, 1882, the far-off sun-spot
+was not improbably connected with the cause.</p>
+
+<p>Probably we should all like to hear some at least equally
+positive conclusion about the weather also, and to learn that
+there was a likelihood of our being able to predict it for the next
+year, as the Signal Service now does for the next day; but there
+is at present no such likelihood. The study of the possible connection
+between sun-spots and the weather is, nevertheless, one
+that will always have great interest to many; for even if we set
+its scientific aim aside and consider it in its purely utilitarian
+aspect, it is evident that the knowledge how to predict whether
+coming harvests would be good or bad, would enable us to do
+for the whole world what Joseph’s prophetic vision of the seven
+good and seven barren years did for the land of Egypt, and
+confer a greater power on its discoverer than any sovereign now
+possesses. There is something to be said, then, for the cyclists;
+for if their zeal does sometimes outrun knowledge, their object
+is a worthy one, and their aims such as we can sympathize with,
+and of which none of us can say that there is any inherent impossibility
+in them, or that they may not conceivably yet lead
+to something. Let us not, then, treat the inquirer who tries to
+connect panics on ‘Change with sun-spots as a mere lunatic; for
+there is this amount of reason in his theory, that the panics,
+together with the general state of business, are connected in
+some obscure way with the good or bad harvests, and these
+again in some still obscurer way with changes in our sun.</p>
+
+<p>We may leave, then, this vision of forecasting the harvests
+and the markets of the world from a study of the sun, as one of
+the fair dreams for the future of our science. Perhaps the dream
+will one day be realized. Who knows?</p>
+
+<hr />
+
+<div id="toclink_91" class="chapter">
+<p><span class="pagenum" id="Page_91">91</span></p>
+
+<h2 class="nobreak" id="IV">IV.<br />
+
+<span class="subhead">THE SUN’S ENERGY (<i>Continued</i>).</span></h2>
+</div>
+
+<p class="drop-cap"><span class="smcap1">If</span> we paused on the words with which our last chapter closed,
+the reader might perhaps so far gather an impression that
+the whole all-important subject of the solar energy was involved
+in mystery and doubt. But if it be indeed a mystery when
+considered in its essence, so are all things; while regarded separately
+in any one of its terrestrial effects of magnetic or chemical
+action, or of light or heat, it may seem less so. Since there is
+not room to consider all these aspects, let us choose the last,
+and look at this energy in its familiar form of the <em>heat</em> by which
+we live.</p>
+
+<p>We, the human race, are warming ourselves at this great fire
+which called our bodies into being, and when it goes out we
+shall go too. What is it? How long has it been? How long
+will it last? How shall we use it?</p>
+
+<p>To look across the space of over ninety million miles, and to
+try to learn from that distance the nature of the solar heat, and
+how it is kept up, seemed to the astronomers of the last century
+a hopeless task. The difficulty was avoided rather than met by
+the doctrine that the sun was pure fire, and shone because “it
+was its nature to.” In the Middle Ages such an idea was universal;
+and along with it, and as a logical sequence of it, the
+belief was long prevalent that it was possible to make another
+such flame here, in the form of a lamp which should burn forever
+and radiate light endlessly without exhaustion. With the<span class="pagenum" id="Page_92">92</span>
+philosopher’s stone, which was to transmute lead into gold, this
+perpetual lamp formed a prime object of research for the alchemist
+and student of magic.</p>
+
+<p>We recall the use which Scott has made of the belief in this
+product of “gramarye” in the “Lay of the Last Minstrel,”
+where it is sought to open the grave of the great wizard in
+Melrose Abbey. It is midnight when the stone which covers
+it is heaved away, and Michael’s undying lamp, buried with him
+long ago, shines out from the open tomb and illuminates the
+darkness of the chancel.</p>
+
+<div class="poetry-container">
+<div class="poetry">
+  <div class="stanza">
+    <div class="verse indentq">“I would you had been there to see</div>
+    <div class="verse indent0">The light break forth so gloriously;</div>
+    <div class="verse indent0">That lamp shall burn unquenchably</div>
+    <div class="verse indent0">Until the eternal doom shall be,”</div>
+  </div>
+</div>
+</div>
+
+<p class="in0">says the poet. Now we are at liberty to enjoy the fiction as a
+fiction; but if we admit that the art which could make such a
+lamp would indeed be a black art, which did not work under
+Nature’s laws, but against them, then we ought to see that as the
+whole conception is derived from the early notion of a miraculous
+constitution of the sun, the idea of an eternal self-sustained
+sun is no more permitted to us than that of an eternal self-sustained
+lamp. We must look for the cause of the sun’s heat
+in Nature’s laws, and we know those laws chiefly by what we
+see here.</p>
+
+<p>Before examining the source of the sun’s heat, let us look a
+little more into its amount. To find the exact amount of heat
+which it sends out is a very difficult problem, especially if we
+are to use all the refinements of the latest methods in determining
+it. The underlying principle, however, is embodied in
+an old method, which gives, it is true, rather crude results, but
+by so simple a treatment that the reader can follow it readily,
+especially if unembarrassed with details, in which most of the
+actual trouble lies. We must warn him in advance that he is<span class="pagenum" id="Page_93">93</span>
+going to be confronted with a kind of enormous sum in multiplication,
+for whose general accuracy he may, however, trust to
+us if he pleases. We have not attempted exact accuracy, because
+it is more convenient for him that we should deal with
+round numbers.</p>
+
+<div id="ip_53" class="figright" style="max-width: 7em;">
+  <img src="images/i_093.png" alt="" />
+  <div class="caption">FIG. 53.—ONE CUBIC
+CENTIMETRE.</div></div>
+
+<div id="ip_54" class="figleft" style="max-width: 6em;">
+  <img src="images/i_093b.png" alt="" />
+  <div class="caption">FIG. 54.—POUILLET’S
+PYRHELIOMETER.</div></div>
+
+<p>The apparatus which we shall need for the attack of this
+great problem is surprisingly simple, and moderate in size. Let
+us begin by finding how much sun-heat falls in a small known
+area. To do this we take a flat, shallow vessel,
+which is to be filled with water. The amount it
+contains is usually a hundred cubic centimetres (a
+centimetre being nearly four-tenths of an inch), so
+that if we imagine a tiny cubical box about as
+large as a backgammon die, or, more exactly,
+having each side just the size of this (<a href="#ip_53">Fig. 53</a>), to
+be filled and emptied into the vessel one hundred times, we
+shall have a precise idea of its limited capacity.
+Into this vessel we dip a thermometer, so as to
+read the temperature of the water, seal all up so
+that the water shall not run out, and expose it so
+that the heat at noon falls perpendicularly on it.
+The apparatus is shown in <a href="#ip_54">Fig. 54</a>, attached to
+a tree. The stem of the instrument holds the
+thermometer, which is upside down, its bulb being
+in the water-vessel. Now, all the sun’s rays do
+not reach this vessel, for some are absorbed by
+our atmosphere; and all the heat which falls on
+it does not stay there, as the water loses part of
+it by the contact of the air with the box outside,
+and in other ways. When allowance is made for these losses,
+we find that the sun’s heat, if all retained, would have raised the
+temperature of the few drops of water which would fill a box
+the size of our little cube (according to these latest observations)<span class="pagenum" id="Page_94">94</span>
+nearly three degrees of the centigrade thermometer in
+one minute,—a most insignificant result, apparently, as a measure
+of what we have been told is the almost infinite heat of
+the sun! But if we think so, we are forgetting the power
+of numbers, of which we are about to have an illustration as
+striking in its way as that which Archimedes once gave with
+the grains of sand.</p>
+
+<p>There is a treatise of his extant, in which he remarks (I cite
+from memory) that as some people believe it possible for numbers
+to express a quantity as great as that of the grains of sand upon
+the sea-shore, while others deny this, he will show that they
+can express one even larger. To prove this beyond dispute, he
+begins by taking a small seed, beside which he ranges single
+grains of sand in a line, till he can give the number of these latter
+which equal its length. Next he ranges seeds beside each
+other till their number makes up the length of a span; then he
+counts the spans in a stadium, and the stadia in the whole world
+as known to the ancients, at each step expressing his results in
+a number certainly <em>greater</em> than the number of sand-grains which
+the seed, or the span, or the stadium, or finally the whole world,
+is thus successively shown to contain. He has then already got
+a number before his reader’s eyes demonstrably larger than that
+of all the grains of sand on the sea-shore; yet he does not stop,
+but steps off the earth into space, to calculate and express a
+number <em>greater</em> than that of all the grains of sand which would
+fill a sphere embracing the earth and the sun!</p>
+
+<p>We are going to use our little unit of heat in the same way,
+for (to calculate in round figures and in English measure) we
+find that we can set over nine hundred of these small cubes side
+by side in a square foot, and, as there are 28,000,000 feet in a
+square mile, that the latter would contain 25,000,000,000 of the
+cubes, placed side by side, touching each other, like a mosaic
+pavement. We find also, by weighing our little cup, that we<span class="pagenum" id="Page_95">95</span>
+should need to fill and empty it almost exactly a million times to
+exhaust a tank containing a ton of water. The sun-heat falling
+on one square mile corresponds, then, to over seven hundred
+and fifty tons of water raised <em>every minute</em> from the freezing-point
+to boiling, which already is becoming a respectable
+amount!</p>
+
+<p>But there are 49,000,000 square miles in the cross-section of
+the earth exposed to the sun’s rays, which it would therefore
+need 1,225,000,000,000,000,000 of our little dies to cover one
+deep; and therefore in each <em>minute</em> the sun’s heat falling on
+the earth would raise to boiling 37,000,000,000 tons of water.</p>
+
+<p>We may express this in other ways, as by the quantity of
+ice it would melt; and as the heat required to melt a given
+weight of ice is 79/100 of that required to bring as much water
+from the freezing to the boiling point, and as the whole surface
+of the earth, including the night side, is four times the cross-section
+exposed to the sun, we find, by taking 526,000 minutes
+to a year, that the sun’s rays would melt in the year a coating
+of ice over the whole earth more than one hundred and sixty
+feet thick.</p>
+
+<p>We have ascended already from our small starting-point to
+numbers which express the heat that falls upon the whole planet,
+and enable us to deal, if we wish, with questions relating to
+the glacial epochs and other changes in its history. We have
+done this by referring at each step to the little cube which we
+have carried along with us, and which is the foundation of all
+the rest; and we now see why such exactness in the first determination
+is needed, since any error is multiplied by enormous
+numbers. But now we too are going to step off the earth and
+to deal with numbers which we can still express in the same way
+if we choose, but which grow so large thus stated that we will
+seek some greater term of comparison for them. We have just
+seen the almost incomprehensible amount of heat which the sun<span class="pagenum" id="Page_96">96</span>
+must send the earth in order to warm its oceans and make green
+its continents; but how little this is to what passes us by! The
+earth as it moves on in its annual path continually comes into
+new regions, where it finds the same amount of heat already
+pouring forth; and this same amount still continues to fall into
+the empty space we have just quitted, where there is no one
+left to note it, and where it goes on in what seems to us utter
+waste. If, then, the whole annual orbit were set close with
+globes like ours, and strung with worlds like beads upon a
+ring, each would receive the same enormous amount the earth
+does now. But this is not all; for not only along the orbit,
+but above and below it, the sun sends its heat in seemingly
+incredible wastefulness, the final amount being expressible in
+the number of <em>worlds</em> like ours that it could warm like ours,
+which is 2,200,000,000.</p>
+
+<p>We have possibly given a surfeit of such numbers, but we
+cannot escape or altogether avoid them when dealing with this
+stupendous outflow of the solar heat. They are too great, perhaps,
+to convey a clear idea to the mind, but let us before leaving
+them try to give an illustration of their significance.</p>
+
+<p>Let us suppose that we could sweep up from the earth all the
+ice and snow on its surface, and, gathering in the accumulations
+which lie on its Arctic and Antarctic poles, commence building
+with it a tower greater than that of Babel, fifteen miles in diameter,
+and so high as to exhaust our store. Imagine that it could
+be preserved untouched by the sun’s rays, while we built on
+with the accumulations of successive winters, until it stretched
+out 240,000 miles into space, and formed an ice-bridge to the
+moon, and that then we concentrated on it the sun’s whole radiation,
+neither more nor less than that which goes on every moment.
+In <em>one</em> second the whole would be gone, melted, boiled,
+and dissipated in vapor. And this is the rate at which the solar
+heat is being (to human apprehension) <em>wasted</em>!</p>
+
+<p><span class="pagenum" id="Page_97">97</span></p>
+
+<p>Nature, we are told, always accomplishes her purpose with
+the least possible expenditure of energy. Is her purpose here,
+then, something quite independent of man’s comfort and happiness?
+Of the whole solar heat, we have just seen that less
+than 1/2,000,000,—less, that is, than the one twenty-thousandth part
+of one per cent,—is made useful to us. “But may there not
+be other planets on which intelligent life exists, and where this
+heat, which passes us by, serves other beings than ourselves?”
+There <em>may</em> be; but if we could suppose all the other planets
+of the solar system to be inhabited, it would help the matter
+very little; for the whole together intercept so little of the great
+sum, that all of it which Nature bestows on man is still as nothing
+to what she bestows on some end—if end there be—which
+is to us as yet inscrutable.</p>
+
+<p>How is this heat maintained? Not by the miracle of a perpetual
+self-sustained flame, we may be sure. But, then, by what
+fuel is such a fire fed? There can be no question of simple
+burning, like that of coal in the grate, for there is no source of
+supply adequate to the demand. The State of Pennsylvania,
+for instance, is underlaid by one of the richest coal-fields of the
+world, capable of supplying the consumption of the whole country
+at its present rate for more than a thousand years to come.
+If the source of the solar heat (whatever that is) were withdrawn,
+and we were enabled to carry this coal there, and shoot it into
+the solar furnace fast enough to keep up the known heat-supply,
+so that the solar radiation would go on at just its actual rate, the
+time which this coal would last is easily calculable. It would
+not last days or hours, but the whole of these coal-beds would
+demonstrably be used up in rather less than one one-thousandth
+of a second! We find by a similar calculation that if the sun
+were itself one solid block of coal, it would have burned out to
+the last cinder in less time than man has certainly been on the
+earth. But during historic times there has as surely been no<span class="pagenum" id="Page_98">98</span>
+noticeable diminution of the sun’s heat, for the olive and the
+vine grow just as they did three thousand years ago, and the
+hypothesis of an actual burning becomes untenable. It has
+been supposed by some that meteors striking the solar surface
+might generate heat by their impact, just as a cannon-ball fired
+against an armor-plate causes a flash of light, and a heat so
+sudden and intense as to partly melt the ball at the instant of
+concussion. This is probably a real source of heat-supply so far
+as it goes, but it cannot go very far; and, indeed, if our whole
+world should fall upon the solar surface like an immense projectile,
+gathering speed as it fell, and finally striking (as it
+would) with the force due to a rate of over three hundred miles
+a second, the heat developed would supply the sun for but little
+more than sixty years.<a id="FNanchor_4" href="#Footnote_4" class="fnanchor">4</a></p>
+
+<div class="footnote">
+
+<p><a id="Footnote_4" href="#FNanchor_4" class="fnanchor">4</a> These estimates differ somewhat from those of Helmholtz and Tyndall, as they
+rest on later measures.</p>
+
+</div>
+
+<p>It is not necessary, however, that a body should be moving
+rapidly to develop heat, for arrested motion always generates it,
+whether the motion be fast or slow, though in the latter case the
+mass arrested must be larger to produce the same result. It is
+in the slow settlement of the sun’s own substance toward its
+centre, as it contracts in cooling, that we find a sufficient cause
+for the heat developed.</p>
+
+<p>This explanation is often unsatisfactory to those who have
+not studied the subject, because the fact that heat is so generated
+is not made familiar to most of us by observation.</p>
+
+<p>Perhaps the following illustration will make the matter
+plainer. When we are carried up in a lift, or elevator, we
+know well enough that heat has been expended under the
+boiler of some engine to drag us up against the power of
+gravity. When the elevator is at the top of its course, it is
+ready to give out in descending just the same amount of power
+needed to raise it, as we see by its drawing up a nearly equal<span class="pagenum" id="Page_99">99</span>
+counterpoise in the descent. It can and must give out in coming
+down the power that was spent in raising it up; and though
+there is no practical occasion to do so, a large part of this power
+could, if we wished, be actually recovered in the form of heat
+again. In the case of a larger body, such as the pyramid of
+Ghizeh, which weighs between six and seven million tons,
+all the furnaces in the world, burning coal under all its engines,
+would have to supply their heat for a measurable time to lift it a
+mile high; and then, if it were allowed to come down, whether
+it tell at once or were made to descend with imperceptible slowness,
+by the time it touched the earth the same heat would be
+given out again.</p>
+
+<p>Perhaps the fact that the sun is gaseous rather than solid
+makes it less easy to realize the enormous weight which is consistent
+with this vaporous constitution. A cubic mile of hydrogen
+gas (the lightest substance known) would weigh much more
+at the sun’s surface than the Great Pyramid does here, and the
+number of these cubic miles in a stratum one mile deep below
+its surface is over 2,000,000,000,000! This alone is enough
+to show that as they settle downward as the solar globe
+shrinks, here is a <em>possible</em> source of supply for all the heat the
+sun sends out. More exact calculation shows that it <em>is</em> sufficient,
+and that a contraction of three hundred feet a year (which in ten
+thousand years would make a shrinkage hardly visible in the
+most powerful telescope) would give all the immense outflow of
+heat which we see.</p>
+
+<p>There is an ultimate limit, however, to the sun’s shrinking,
+and there must have been some bounds to the heat he can
+already have thus acquired; for—though the greater the
+original diameter of his sphere, the greater the gain of heat
+by shrinking to its present size—if the original diameter be
+supposed as great as possible, there is still a finite limit to the
+heat gained.</p>
+
+<p><span class="pagenum" id="Page_100">100</span></p>
+
+<p>Suppose, in other words, the sun itself and all the planets
+ground to powder, and distributed on the surface of a sphere
+whose radius is infinite, and that this matter (the same in
+amount as that constituting the present solar system) is allowed
+to fall together at the centre. The actual shrinkage cannot
+possibly be greater than in this extreme case; but even in this
+practically impossible instance, it is easy to calculate that the
+heat given out would not support the <em>present</em> radiation over
+eighteen million years, and thus we are enabled to look back
+over past time, and fix an approximate limit to the age of the
+sun and earth.</p>
+
+<p>We say “present” rate of radiation, because, so long as the
+sun is purely gaseous, its temperature rises as it contracts, and
+the heat is spent faster; so that in early ages before this temperature
+was as high as it is now, the heat was spent more
+slowly, and what could have lasted “only” eighteen million
+years at the present rate might have actually spread over an
+indefinitely greater time in the past; possibly covering more
+than all the æons geologists ask for.</p>
+
+<p>If we would look into the future, also, we find that at the
+present rate we may say that the sun’s heat-supply is enough to
+last for some such term as four or five million years before it
+sensibly fails. It is certainly remarkable that by the aid of our
+science man can look out from this “bank and shoal of time,”
+where his fleeting existence is spent, not only back on the almost
+infinite lapse of ages past, but that he can forecast with some
+sort of assurance what is to happen in an almost infinitely distant
+future, long after the human race itself will have disappeared
+from its present home. But so it is, and we may say—with
+something like awe at the meaning to which science points—that
+the whole future radiation cannot last so long as ten million
+years. Its probable life in its present condition is covered by
+about thirty million years. No reasonable allowance for the fall<span class="pagenum" id="Page_101">101</span>
+of meteors or for all other known causes of supply could possibly
+at the present rate of radiation raise the whole term of its
+existence to sixty million years.</p>
+
+<p>This is substantially Professor Young’s view, and he <span class="locked">adds:—</span></p>
+
+<div class="blockquot">
+
+<p>“At the same time it is, of course, impossible to assert that there has
+been no catastrophe in the past, no collision with some wandering star
+... producing a shock which might in a few hours, or moments even,
+restore the wasted energy of ages. Neither is it wholly safe to assume
+that there may not be ways, of which we as yet have no conception, by
+which the energy apparently lost in space may be returned. But the
+whole course and tendency of Nature, so far as science now makes
+out, points backward to a beginning and forward to an end. The
+present order of things seems to be bounded both in the past and in
+the future by terminal catastrophes which are veiled in clouds as yet
+inscrutable.”</p>
+</div>
+
+<p>There is another matter of interest to us as dwellers on this
+planet, connected not with the amount of the sun’s heat so much
+as with the degree of its temperature; for it is almost certain
+that a very little fall in the temperature will cause an immense
+and wholly disproportionate diminution of the heat-supply. The
+same principle may be observed in more familiar things. We
+can, for instance, warm quite a large house by a very small furnace,
+if we urge this (by a wasteful use of coal) to a dazzling
+white heat. If we now let the furnace cool to half this white-heat
+temperature, we shall be sure to find that the heat radiated
+has not diminished in proportion, but out of all proportion,—has
+sunk, for instance, not only to one-half what it was (as we
+might think it would do), but to perhaps a twentieth or even
+less, so that the furnace which heated the house can no longer
+warm a single room.</p>
+
+<p>The human race, as we have said, is warming itself at the
+great solar furnace, which we have just seen contains an internal
+source for generating heat enough for millions of years to come;
+but we have also learned that if the sun’s internal circulation<span class="pagenum" id="Page_102">102</span>
+were stopped, the surface would cool and shut up the heat
+inside, where it would do us no good. The <em>temperature</em> of the
+surface, then, on which the rate of heat-emission depends, concerns
+us very much; and if we had a thermometer so long that
+we could dip its bulb into the sun and read the degrees on the
+stem here, we should find out what observers would very much
+like to know, and at present are disposed to quarrel about. The
+difficulty is not in measuring the heat,—for that we have just
+seen how to do,—but in telling what temperature corresponds
+to it, since there is no known rule by which to find one from the
+other. One certain thing is this—that we cannot by any contrivance
+raise the temperature in the focus of any lens or mirror
+beyond that of its source (practically we cannot do even so
+much); we cannot, for instance, by any burning-lens make the
+image of a candle as hot as the original flame. Whatever a
+thermometer may read when the candle-heat is concentrated on
+its bulb by a lens, it would read yet more if the bulb were
+dipped in the candle-flame itself; and one obvious application
+of this fact is that though we cannot dip our thermometer in the
+sun, we know that if we could do so, the temperature would at
+least be greater than any we get by the largest burning-glass.
+We need have no fear of making the burning-glass too big; the
+temperature at its solar focus is <em>always</em> and necessarily lower
+than that of the sun itself.</p>
+
+<p>For some reason no very great burning-lens or mirror has
+been constructed for a long time, and we have to go back to the
+eighteenth century to see what can be done in this way. The
+annexed figure (<a href="#ip_55">Fig. 55</a>) is from a wood-cut of the last century,
+describing the largest burning-lens then or since constructed
+in France, whose size and mode of use the drawing clearly
+shows. All the heat falling on the great lens was concentrated
+on a smaller one, and the smaller one concentrated it
+in turn, till at the very focus we are assured that iron, gold,<span class="pagenum" id="Page_103">103</span>
+and other metals ran like melted butter. In England, the
+largest burning-lens on record was made about the same time
+by an optician named Parker for the English Government, who
+designed it as a present to be taken by Lord Macartney’s embassy
+to the Emperor of China. Parker’s lens was three feet
+in diameter and very massive, being seven inches thick at the
+centre. In its focus the most refractory substances were fused,
+and even the diamond was reduced to vapor, so that the
+temperature of the sun’s surface is at any rate higher than
+<em>this</em>.</p>
+
+<div id="ip_55" class="figcenter" style="max-width: 31em;">
+  <img src="images/i_103.jpg" alt="" />
+  <div class="caption">FIG. 55.—BERNIÈRES’S GREAT BURNING-GLASS. (AFTER AN OLD FRENCH PRINT.)</div></div>
+
+<p>(What became of the French lens shown, it would be interesting
+to know. If it is still above ground, its fate has been
+better than that of the English one. It is said that the Emperor
+of China, when he got his lens, was much alarmed by it, as
+being possibly sent him by the English with some covert
+design for his injury. By way of a test, a smith was ordered<span class="pagenum" id="Page_104">104</span>
+to strike it with his hammer; but the hammer rebounded from
+the solid glass, and this was taken to be conclusive evidence
+of magic in the thing, which was immediately buried, and probably
+is still reposing under the soil of the Celestial Flowery
+Kingdom.)</p>
+
+<p>We can confirm the evidence of such burning-lenses as to
+the sun’s high temperature by another class of experiment,
+which rests on an analogous principle. We can make the
+comparison between the heat from some artificially heated
+object and that which would be given out from an equal area
+of the sun’s face. Now, supposing like emissive powers, if the
+latter be found the hotter, though we cannot tell what its
+temperature absolutely is, we can at least say that it is greater
+than that of the thing with which it is compared; so that we
+choose for comparison the hottest thing we can find, on a
+scale large enough for the experiment. One observation of
+my own in this direction I will permit myself to cite in illustration.</p>
+
+<p>Perhaps the highest temperature we can get on a large scale
+in the arts is that of molten steel in the Bessemer converter. As
+many may be as ignorant of what this is as I was before I tried
+the experiment, I will try to describe it.</p>
+
+<div id="ip_56" class="figcenter" style="max-width: 34em;">
+  <img src="images/i_105.jpg" alt="" />
+  <div class="caption">FIG. 56.—A “POUR” FROM THE BESSEMER CONVERTER.</div></div>
+
+<p>The “converter” is an enormous iron pot, lined with fire-brick,
+and capable of holding thirty or forty thousand pounds
+of melted metal; and it is swung on trunnions, so that it can
+be raised by an engine to a vertical position, or lowered by
+machinery so as to pour its contents out into a caldron. First
+the empty converter is inclined, and fifteen thousand pounds
+of fluid iron streams down into the mouth from an adjacent
+furnace where it has been melted. Then the engine lifts the
+converter into an erect position, while an air-blast from a
+blowing-engine is forced in at the bottom and through the
+liquid iron, which has combined with it nearly half a ton of<span class="pagenum" id="Page_107">107</span>
+silicon and carbon,—materials which, with the oxygen of the
+blast, create a heat which leaves that of the already molten iron
+far behind. After some time the converter is tipped forward,
+and fifteen hundred pounds more of melted iron is added to that
+already in it. What the temperature of this last is, may be
+judged from the fact that though ordinary melted iron is dazzlingly
+bright, the melted metal in the converter is so much
+brighter still, that the entering stream is dark brown by comparison,
+presenting a contrast like that of chocolate poured into a
+white cup. The contents are now no longer iron, but liquid
+steel, ready for pouring into the caldron; and, looking from the
+front down into the inclined vessel, we see the almost blindingly
+bright interior dripping with the drainage of the metal running
+down its side, so that the circular mouth, which is twenty-four
+inches in diameter, presents the effect of a disk of molten metal
+of that size (were it possible to maintain such a disk in a vertical
+position). In addition, we have the actual stream of falling
+metal, which continues nearly a minute, and presents an area
+of some square feet. The shower of scintillations from this cataract
+of what seems at first “sunlike” brilliancy, and the area
+whence such intense heat and light are for a brief time radiated,
+make the spectacle a most striking one. (See <a href="#ip_56">Fig. 56</a>.)</p>
+
+<p>The “pour” is preceded by a shower of sparks, consisting of
+little particles of molten steel which are projected fully a hundred
+feet in the direction of the open mouth of the converter.
+In the line of this my apparatus was stationed in an open window,
+at a point where its view could be directed down into the
+converter on one side, and up at the sun on the other. This
+apparatus consisted of a long photometer-box with a <i xml:lang="fr" lang="fr">porte-lumière</i>
+at one end. The mirror of this reflected the sun’s rays through
+the box and then on to the pouring metal, tracing their way to
+it by a beam visible in the dusty air (<a href="#ip_57">Fig. 57</a>). In the path of
+this beam was placed the measuring apparatus, both for heat and<span class="pagenum" id="Page_108">108</span>
+light. As the best point of observation was in the line of the
+blast, a shower of sparks was driven over the instrument and
+observer at every “pour;” and the rain of wet soot from chimneys
+without, the bombardment from within, and the moving
+masses of red-hot iron around, made the experiment an altogether
+peculiar one. The apparatus
+was arranged in such a way that the
+effect (except for the absorption of its
+beams on the way) was independent of
+the size or distance of the sun, and depended
+on the absolute radiation there,
+and was equivalent, in fact, to taking a
+sample piece of the sun’s face <em>of equal
+size</em> with the fluid metal, bringing them
+face to face, and seeing which was the
+hotter and brighter. The comparison,
+however, was unfair to the sun, because
+its rays were in reality partly absorbed
+by the atmosphere on the way, while
+those of the furnace were not. Under
+these circumstances the heat from any
+single square foot of the sun’s surface
+was found to be <em>at least</em> eighty-seven
+times that from a square foot of the
+melted metal, while the light from the
+sun was proved to be, foot for foot, over
+five thousand times that from the molten
+steel, though the latter, separately considered,
+seemed to be itself, as I have
+said, of quite sunlike brilliancy.</p>
+
+<div id="ip_57" class="figcenter" style="max-width: 34em;">
+  <img src="images/i_108.png" alt="" />
+  <div class="caption">FIG. 57.—PHOTOMETER-BOX.</div></div>
+
+<p>We must not conclude from this that the <em>temperature</em> of the
+sun was five thousand times that of the steel, but we may be
+certain that it was at any rate a great deal the higher of the two.
+It is probable, from all experiments made up to this date, that<span class="pagenum" id="Page_109">109</span>
+the solar effective temperature is not less than 3,000 nor more
+than 30,000 degrees of the centigrade thermometer. Sir William
+Siemens, whose opinion on any question as to heat is entitled to
+great respect, thought the lower value nearer the truth, but this
+is doubtful.</p>
+
+<div id="ip_58" class="figcenter" style="max-width: 32em;">
+  <img src="images/i_109.jpg" alt="" />
+  <div class="caption">FIG. 58.—MOUCHOT’S SOLAR ENGINE. (FROM A FRENCH PRINT.)</div></div>
+
+<p><span class="pagenum" id="Page_111">111</span></p>
+
+<div class="tb">* * * * *</div>
+
+<p>We have, in all that has preceded, been speaking of the sun’s
+constitution and appearance, and have hardly entered on the
+question of its industrial relations to man. It must be evident,
+however, that if we derive, as it is asserted we do, almost all
+our mechanical power from this solar heat,—if our water-wheel
+is driven by rivers which the sun feeds by the rain he sucks up
+for them into the clouds, if the coal is stored sun-power, and if,
+as Stevenson said, it really is the sun which drives our engines,
+though at second hand,—there is an immense fund of possible
+mechanical power still coming to us from him which might be
+economically utilized. Leaving out of sight all our more important
+relations to him (for, as has been already said, he is in a
+physical sense our creator, and he keeps us alive from hour to
+hour), and considering him only as a possible servant to grind
+our corn and spin our flax, we find that even in this light there
+are startling possibilities of profit in the study of our subject.
+From recent measures it appears that from every square yard of
+the earth exposed perpendicularly to the sun’s rays, in the absence
+of an absorbing atmosphere, there could be derived more
+than one horse-power, if the heat were all converted into this
+use, and that even on such a little area as the island of Manhattan,
+or that occupied by the city of London, the noontide heat
+is enough, could it all be utilized, to drive all the steam-engines
+in the world. It will not be surprising, then, to hear that many
+practical men are turning their attention to this as a source of
+power, and that, though it has hitherto cost more to utilize the<span class="pagenum" id="Page_112">112</span>
+power than it is worth, there is reason to believe that some of
+the greatest changes which civilization has to bring may yet be
+due to such investigations. The visitor to the last Paris Exposition
+may remember an extraordinary machine on the grounds
+of the Trocadéro, looking like a gigantic inverted umbrella
+pointed sunward. This was the sun-machine of M. Mouchot,
+consisting of a great parabolic reflector, which concentrated the
+heat on a boiler in the focus and drove a steam-engine with it,
+which was employed in turn to work a printing-press, as our
+engraving shows (<a href="#ip_58">Fig. 58</a>). Because these constructions have
+been hitherto little more than playthings, we are not to think of
+them as useless. If toys, they are the toys of the childhood of a
+science which is destined to grow, and in its maturity to apply
+this solar energy to the use of all mankind.</p>
+
+<p>Even now they are beginning to pass into the region of
+practical utility, and in the form of the latest achievement of
+Mr. Ericsson’s ever-young genius are ready for actual work on
+an economical scale. We present in <a href="#ip_59">Fig. 59</a> his new actually
+working solar engine, which there is every reason to believe is
+more efficient than Mouchot’s, and probably capable of being
+used with economical advantage in pumping water in desert
+regions of our own country. It is pregnant with suggestion of
+the future, if we consider the growing demand for power in the
+world, and the fact that its stock of coal, though vast, is strictly
+limited, in the sense that when it <em>is</em> gone we can get absolutely
+no more. The sun has been making a little every day for
+millions of years,—so little and for so long, that it is as though
+time had daily dropped a single penny into the bank to our
+credit for untold ages, until an enormous fund had been thus
+slowly accumulated in our favor. We are drawing on this fund
+like a prodigal who thinks his means endless, but the day will
+come when our check will no longer be honored, and what shall
+we do then?</p>
+
+<p><span class="pagenum" id="Page_113">113</span></p>
+
+<div id="ip_59" class="figcenter" style="max-width: 33em;">
+  <img src="images/i_113.jpg" alt="" />
+  <div class="caption">FIG. 59.—ERICSSON’S NEW SOLAR ENGINE, NOW IN PRACTICAL USE IN NEW YORK.</div></div>
+
+<p><span class="pagenum" id="Page_115">115</span></p>
+
+<p>The exhaustion of some of the coal-beds is an affair of the
+immediate future, by comparison with the vast period of time we
+have been speaking of. The English coal-beds, it is asserted,
+will, from present indications, be quite used up in about three
+hundred years more.</p>
+
+<p>Three hundred years ago, the sun, looking down on the England
+of our forefathers, saw a fair land of green woods and quiet
+waters, a land unvexed with noisier machinery than the spinning-wheel,
+or the needles of the “free maids that weave their threads
+with bones.” Because of the coal which has been dug from its
+soil, he sees it now soot-blackened, furrowed with railway-cuttings,
+covered with noisy manufactories, filled with grimy
+operatives, while the island shakes with the throb of coal-driven
+engines, and its once quiet waters are churned by the wheels of
+steamships. Many generations of the lives of men have passed
+to make the England of Elizabeth into the England of Victoria;
+but what a moment this time is, compared with the vast lapse of
+ages during which the coal was being stored! What a moment
+in the life of the “all-beholding sun,” who in a few hundred
+years—his gift exhausted and the last furnace-fire out—may
+send his beams through rents in the ivy-grown walls of deserted
+factories, upon silent engines brown with rust, while the mill-hand
+has gone to other lands, the rivers are clean again, the harbors
+show only white sails, and England’s “black country” is
+green once more! To America, too, such a time may come,
+though at a greatly longer distance.</p>
+
+<p>Does this all seem but the idlest fancy? That something
+like it will come to pass sooner or later, is a most certain fact—as
+certain as any process of Nature—if we do not find a new
+source of power; for of the coal which has supplied us, after a
+certain time we can get no more.</p>
+
+<p>Future ages may see the seat of empire transferred to regions
+of the earth now barren and desolated under intense solar heat,—countries<span class="pagenum" id="Page_116">116</span>
+which, for that very cause, will not improbably
+become the seat of mechanical and thence of political power.
+Whoever finds the way to make industrially useful the vast sun-power
+now wasted on the deserts of North Africa or the shores
+of the Red Sea, will effect a greater change in men’s affairs than
+any conqueror in history has done; for he will once more people
+those waste places with the life that swarmed there in the best
+days of Carthage and of old Egypt, but under another civilization,
+where man no longer shall worship the sun as a god, but
+shall have learned to make it his servant.</p>
+
+<hr />
+
+<div id="toclink_117" class="chapter">
+<p><span class="pagenum" id="Page_117">117</span></p>
+
+<h2 class="nobreak" id="V">V.<br />
+
+<span class="subhead">THE PLANETS AND THE MOON.</span></h2>
+</div>
+
+<p class="drop-cap"><span class="smcap1">When</span> we look up at the heavens, we see, if we watch
+through the night, the host of stars rising in the east
+and passing above us to sink in the west, always at the same
+distance and in unchanging order, each seeming a point of light
+as feeble as the glow-worm’s shine in the meadow over which
+they are rising, each flickering as though the evening wind
+would blow it out. The infant stretches out its hand to grasp
+the Pleiades; but when the child has become an old man the
+“seven stars” are still there unchanged, dim only in his aged
+sight, and proving themselves the enduring substance, while it
+is his own life which has gone, as the shine of the glow-worm in
+the night. They were there just the same a hundred generations
+ago, before the Pyramids were built; and they will tremble there
+still, when the Pyramids have been worn down to dust with the
+blowing of the desert sand against their granite sides. They
+watched the earth grow fit for man long before man came, and
+they will doubtless be shining on when our poor human race
+itself has disappeared from the surface of this planet.</p>
+
+<p>Probably there is no one of us who has not felt this solemn
+sense of their almost infinite duration as compared with his own
+little portion of time, and it would be a worthy subject for our
+thought if we could study them in the light that the New Astronomy
+sheds for us on their nature. But I must here confine<span class="pagenum" id="Page_118">118</span>
+myself to the description of but a few of their number, and
+speak, not of the infinite multitude and variety of stars, each a
+self-shining sun, but only of those which move close at hand;
+for it is not true of quite all that they keep at the same distance
+and order.</p>
+
+<p>Of the whole celestial army which the naked eye watches,
+there are five stars which do change their places in the ranks,
+and these change in an irregular and capricious manner, going
+about among the others, now forward and now back, as if lost
+and wandering through the sky. These wanderers were long
+since known by distinct names, as Mercury, Venus, Mars, Jupiter,
+and Saturn, and believed to be nearer than the others; and
+they are, in fact, companions to the earth and fed like it by the
+warmth of our sun, and like the moon are visible by the sunlight
+which they reflect to us. With the earliest use of the telescope,
+it was found that while the other stars remained in it
+mere points of light as before, these became magnified into
+disks on which markings were visible, and the markings have
+been found with our modern instruments, in one case at least, to
+take the appearance of oceans and snow-capped continents and
+islands. These, then, are not uninhabitable self-shining suns,
+but worlds, vivified from the same fount of energy that supplies
+us, and the possible abode of creatures like ourselves.</p>
+
+<div id="ip_60" class="figcenter" style="max-width: 34em;">
+  <img src="images/i_119.jpg" alt="" />
+  <div class="caption">FIG. 60.—SATURN. (FROM A DRAWING BY TROUVELOT).</div></div>
+
+<p>“Properly speaking,” it is said, “man is the only subject of
+interest to man;” and if we have cared to study the uninhabitable
+sun because all that goes on there is found to be so intimately
+related to us, it is surely a reasonable curiosity which
+prompts the question so often heard as to the presence of life on
+these neighbor worlds, where it seems at least not impossible
+that life should exist. Even the very little we can say in answer
+to this question will always be interesting; but we must
+regretfully admit at the outset that it is but little, and that with
+some planets, like Mercury and Venus, the great telescopes of<span class="pagenum" id="Page_121">121</span>
+modern times cannot do much more than those of Galileo, with
+which our New Astronomy had its beginning.</p>
+
+<p>Let us leave these, then, and pass out to the confines of the
+planetary system, where we may employ our telescopes to better
+advantage.</p>
+
+<p>The outer planets, Neptune and Uranus, remain pale disks
+in the most powerful instruments, the first attended by a single
+moon, the second by four, barely visible; and there is so very
+little yet known about their physical features, that we shall do
+better to give our attention to one of the most interesting objects
+in the whole heavens,—the planet Saturn, on which we can at
+any rate see enough to arouse a lively curiosity to know more.</p>
+
+<p>When Galileo first turned his glass on Saturn, he saw, as he
+thought, that it consisted of three spheres close together, the
+middle one being the largest. He was not quite sure of the fact,
+and was in a dilemma between his desire to wait longer for
+further observation, and his fear that some other observer might
+announce the discovery if he hesitated. To combine these incompatibilities—to
+announce it so as to secure the priority, and
+yet not announce it till he was ready—might seem to present
+as great a difficulty as the discovery itself; but Galileo solved
+this, as we may remember, by writing it in the sentence, “Altissimum
+planetam tergeminum observavi” (“I have observed the
+highest planet to be triple”), and then throwing it (in the
+printer’s phrase) “into pi,” or jumbling the letters, which
+made the sentence into the monstrous word</p>
+
+<p class="p1 b1 center">
+SMAJSMRMJLMEBOETALEVMJPVNENVGTTAVJRAS,
+</p>
+
+<p class="in0">and publishing <em>this</em>, which contained his discovery, but under
+lock and key. He had reason to congratulate himself on his
+prudence, for within two years two of the supposed bodies disappeared,
+leaving only one. This was in 1612; and for nearly
+fifty years Saturn continued to all astronomers the enigma<span class="pagenum" id="Page_122">122</span>
+which it was to Galileo, till in 1656 it was finally made clear
+that it was surrounded by a thin flat ring, which when seen
+fully gave rise to the first appearance in Galileo’s small telescope,
+and when seen edgewise disappeared from its view altogether.
+Everything in this part of our work depends on the
+power of the telescope we employ, and in describing the modern
+means of observation we pass over two centuries of slow advance,
+each decade of which has marked some progress in the
+instrument, to one of its completest types, in the great equatorial
+at Washington, shown in <a href="#ip_61">Fig. 61</a>.</p>
+
+<div id="ip_61" class="figcenter" style="max-width: 20em;">
+  <img src="images/i_122.jpg" alt="" />
+  <div class="caption">FIG. 61.—THE EQUATORIAL TELESCOPE AT WASHINGTON.</div></div>
+
+<p>The revolving dome above, the great tube beneath, its massive
+piers, and all its accessories are only means to carry and<span class="pagenum" id="Page_123">123</span>
+direct the great lens at the further end, which acts the part of
+the lens in our own eye, and forms the image of the thing to be
+looked at. Galileo’s original lens was a single piece of glass,
+rather smaller than that of our common spectacles; but the lens
+here is composed of two pieces, each twenty-six inches in diameter,
+and collects as much light as a human eye would do if over
+two feet across. But this is useless if the lens is not shaped
+with such precision as to send every ray to its proper place
+at the eye-piece, nearly thirty-five feet away; and, in fact, the
+shape given its surface by the skilful hands of the Messrs.
+Clark, who made it, is so exquisitely exact that all the light
+of a star gathered by this great surface is packed at the distant
+focus into a circle very much smaller than that made by the dot
+on this <i>i</i>, and the same statement may be made of the great Lick
+glass, which is three feet in diameter,—an accuracy we might
+call incredible were it not certain. It is with instruments of
+such accuracy that astronomy now works, and it is with this
+particular one that some of the observations we are going to
+describe have been made.</p>
+
+<p>In all the heavens there is no more wonderful object than
+Saturn, for it preserves to us an apparent type of the plan on
+which all the worlds were originally made. Let us look at it
+in this study by Trouvelot (<a href="#ip_60">Fig. 60</a>). The planet, we must remember,
+is a globe nearly seventy thousand miles in diameter,
+and the outermost ring is over one hundred and fifty thousand
+miles across, so that the proportionate size of our earth would be
+over-represented here by a pea laid on the engraving. The
+belts on the globe show delicate tints of brown and blue, and
+parts of the ring are, as a whole, brighter than the planet; but
+this ring, as the reader may see, consists of at least three main
+divisions, each itself containing separate features. First is the
+gray outer ring, then the middle one, and next the curious
+“crape” ring, very much darker than the others, looking like<span class="pagenum" id="Page_124">124</span>
+a belt where it crosses the planet, and apparently feebly transparent,
+for the outline of the globe has been seen (though not
+very distinctly) <em>through</em> it. The whole system of rings is of the
+most amazing thinness, for it is probably thinner in proportion
+to its size than the paper on which this is printed is to the width
+of the page; and when it is turned edgewise to us, it disappears
+to all but the most powerful telescopes, in which it looks then
+like the thinnest conceivable line of light, on which the moons
+have been seen projected, appearing like beads sliding along
+a golden wire. The globe of the planet casts on the ring a
+shadow, which is here shown as a broken line, as though the
+level of the rings were suddenly disturbed. At other times (as
+in a beautiful drawing made with the same instrument by Professor
+Holden) the line seems continuous, though curved as
+though the middle of the ring system were thicker than the
+edge. The rotation of the ring has been made out by direct
+observations; and the whole is in motion about the globe,—a
+motion so smooth and steady that there is no flickering in the
+shadow “where Saturn’s steadfast shade sleeps on its luminous
+ring.”</p>
+
+<div id="ip_62" class="figcenter" style="max-width: 36em;">
+  <img src="images/i_125.jpg" alt="" />
+  <div class="caption">FIG. 62.—JUPITER, MOON, AND SHADOW. (BY PERMISSION OF WARREN DE LA RUE.)</div></div>
+
+<p>What is it? No solid could hold together under such conditions;
+we can hardly admit the possibility of its being a liquid
+film extended in space; and there are difficulties in admitting
+it to be gaseous. But if not a solid, a liquid, or a gas, again
+what can it be? It was suggested nearly two centuries ago
+that the ring might be composed of innumerable little bodies
+like meteorites, circling round the globe so close together as to
+give the appearance we see, much as a swarm of bees at a distance
+looks like a continuous cloud; and this remains the most
+plausible solution of what is still in some degree a mystery.
+Whatever it be, we see in the ring the condition of things
+which, according to the nebular hypothesis, once pertained to
+all the planets at a certain stage of their formation; and this,<span class="pagenum" id="Page_127">127</span>
+with the extraordinary lightness of the globe (for the whole
+planet would float on water), makes us look on it as still in the
+formative stage of uncondensed matter, where the solid land as
+yet is not, and the foot could find no resting-place. Astrology
+figured Saturn as “spiteful and cold,—an old man melancholy;”
+but if we may indulge such a speculation, modern
+astronomy rather leads us to think of it as in the infancy of
+its life, with every process of planetary growth still in its future,
+and separated by an almost unlimited stretch of years from the
+time when life under the conditions in which we know it can
+even begin to exist.</p>
+
+<div class="tb">* * * * *</div>
+
+<p>Like this appears also the condition of Jupiter (<a href="#ip_62">Fig. 62</a>), the
+greatest of the planets, whose globe, eighty-eight thousand
+miles in diameter, turns so rapidly that the centrifugal force
+causes a visible flattening. The belts which stretch across its
+disk are of all delicate tints—some pale blue, some of a crimson
+lake; a sea-green patch has been seen, and at intervals of late
+years there has been a great oval red spot, which has now
+nearly gone, and which our engraving does not show. The
+belts are largely, if not wholly, formed of rolling clouds, drifting
+and changing under our eyes, though more rarely a feature like
+the oval spot just mentioned will last for years, an enduring
+enigma. The most recent observations tend to make us believe
+that the equatorial regions of Jupiter, like those of the sun,
+make more turns in a year than the polar ones; while the darkening
+toward the edge is another sunlike feature, though perhaps
+due to a distinct cause, and this is beautifully brought out
+when any one of the four moons which circle the planet passes
+between us and its face, an occurrence also represented in our
+figure. The moon, as it steals on the comparatively dark edge,
+shows us a little circle of an almost lemon-yellow, but the effect
+of contrast grows less as it approaches the centre. Next (or<span class="pagenum" id="Page_128">128</span>
+sometimes before), the disk is invaded by a small and intensely
+black spot, the shadow of the moon, which slides across the
+planet’s face, the transit lasting long enough for us to see that
+the whole great globe, serving as a background for the spectacle,
+has visibly revolved on its axis since we began to gaze.
+Photography, in the skilful hands of the late Professor Henry
+Draper, gave us reason to suspect the possibility that a dull
+light is sent to us from parts of the planet’s surface besides what
+it reflects, as though it were still feebly glowing like a nearly
+extinguished sun; and, on the whole, a main interest of these
+features to us lies in the presumption they create that the giant
+planet is not yet fit to be the abode of life, but is more probably
+in a condition like that of our earth millions of years since, in a
+past so remote that geology only infers its existence, and long
+before our own race began to be. That science, indeed, itself
+teaches us that such all but infinite periods are needed to prepare
+a planet for man’s abode, that the entire duration of his
+race upon it is probably brief in comparison.</p>
+
+<div class="tb">* * * * *</div>
+
+<p>We pass by the belt of asteroids, and over a distance many
+times greater than that which separates the earth from the sun,
+till we approach our own world. Here, close beside it as it
+were, in comparison with the enormous spaces which intervene
+between it and Saturn and Jupiter, we find a planet whose size
+and features are in striking contrast to those of the great globe
+we have just quitted. It is Mars, which shines so red and looks
+so large in the sky because it is so near, but whose diameter
+is only about half that of our earth. This is indeed properly to
+be called a neighbor world, but the planetary spaces are so immense
+that this neighbor is at closest still about thirty-four
+million miles away.</p>
+
+<div id="ip_63" class="figcenter" style="max-width: 34em;">
+  <img src="images/i_129.jpg" alt="" />
+  <div class="caption">FIG 63.—THREE VIEWS OF MARS.</div></div>
+
+<div id="ip_64" class="figcenter" style="max-width: 34em;">
+  <img src="images/i_129b.jpg" alt="" />
+  <div class="caption">FIG 64.—MAP OF MARS.</div></div>
+
+<p>Looking across that great gulf, we see in our engraving
+(<a href="#ip_63">Fig. 63</a>)—where we have three successive views taken at intervals<span class="pagenum" id="Page_129">129</span>
+of a few hours—a globe not marked by the belts of Jupiter
+or Saturn, but with outlines as of continents and islands, which
+pass in turn before our eyes as it revolves in a little over
+twenty-four and a half of our hours, while at either pole is a
+white spot. Sir William Herschel was the first to notice that
+this spot increased in size when it was turned away from the
+sun, and diminished when the solar heat fell on it; so that we
+have what is almost proof that here is ice (and consequently<span class="pagenum" id="Page_130">130</span>
+water) on another world. Then, as we study more, we discern
+forms which move from day to day on the globe apart from
+its rotation, and we recognize in them clouds sweeping over
+the surface,—not a surface of still other clouds below,
+but of what we have good reason to believe to be land and
+water.</p>
+
+<p>By the industry of numerous astronomers, seizing every
+favorable opportunity when Mars comes near, so many of these
+features have been gathered that we have been enabled to make
+fairly complete maps of the planet, one of which by Mr. Green
+is here given (<a href="#ip_64">Fig. 64</a>).</p>
+
+<p>Here we see the surface more diversified than that of our
+earth, while the oceans are long, narrow, canal-like seas, which
+everywhere invade the land, so that on Mars one could travel
+almost everywhere by water. These canals seem also in some
+cases to exist in pairs or to be remarkably duplicated. The
+spectroscope indicates water-vapor in the Martial atmosphere,
+and some of the continents, like “Lockyer Land,” are sometimes
+seen white, as though covered with ice: while one island
+(marked on our map as Hall Island) has been seen so frequently
+thus, that it is very probable that here some mountain or tableland
+rises into the region of perpetual snow.</p>
+
+<p>The cause of the red color of Mars has never been satisfactorily
+ascertained. Its atmosphere does not appear to be dark
+enough to produce such an effect, and perhaps as probable an
+explanation as any is one the suggestion of which is a little
+startling at first. It is that vegetation on Mars may be <em>red</em> instead
+of green! There is no intrinsic improbability in the idea,
+for we are even to-day unprepared to say with any certainty
+why vegetation is green here, and it is quite easy to conceive of
+atmospheric conditions which would make red the best absorber
+of the solar heat. Here, then, we find a planet on which we
+obtain many of the conditions of life which we know ourselves,<span class="pagenum" id="Page_131">131</span>
+and here, if anywhere in the system, we may allowably inquire
+for evidence of the presence of something like our own race;
+but though we may indulge in supposition, there is unfortunately
+no prospect that with any conceivable improvement in
+our telescopes we shall ever obtain anything like certainty. We
+cannot assert that there are any bounds to man’s invention, or
+that science may not, by some means as unknown to us as the
+spectroscope was to our grandfathers, achieve what now seems
+impossible; but to our present knowledge no such means exist,
+though we are not forbidden to look at the ruddy planet with
+the feeling that it may hold possibilities more interesting to our
+humanity than all the wonders of the sun, and all the uninhabitable
+immensities of his other worlds.</p>
+
+<p>Before we leave Mars, we may recall to the reader’s memory
+the extraordinary verification of a statement made about it more
+than a hundred years ago. We shall have for a moment to
+leave the paths of science for those of pure fiction, for the words
+we are going to quote are those of no less a person than our old
+friend Captain Gulliver, who, after his adventures with the Lilliputians,
+went to a flying island inhabited largely by astronomers.
+If the reader will take down his copy of Swift, he will
+find in this voyage of Gulliver’s to Laputa the following imaginary
+description of what its imaginary astronomers <span class="locked">saw:—</span></p>
+
+<div class="blockquot">
+
+<p>“They have likewise discovered two lesser stars or satellites which
+revolve about Mars, whereof the innermost is distant from the centre
+of the primary planet exactly three of its diameters, and the outermost
+five; the former revolves in the space of ten hours, and the latter in
+twenty-one and a half.”</p>
+</div>
+
+<p>Now, compare this passage, which was published in the year
+1727, with the announcement in the scientific journals of August,
+1877 (a hundred and fifty years after), that two moons
+did exist, and had just been discovered by Professor Hall, of<span class="pagenum" id="Page_132">132</span>
+Washington, with the great telescope of which a drawing has
+been already given. The resemblance does not end even here,
+for Swift was right also in describing them as very near the
+planet and with very short periods, the actual distances being
+about one and a half and seven diameters, and the actual times
+about eight and thirty hours respectively,—distances and periods
+which, if not exactly those of Swift’s description, agree with it
+in being less than any before known in the solar system. It is
+certain that there could not have been the smallest ground for
+a suspicion of their existence when “Gulliver’s Travels” was
+written, and the coincidence—which is a pure coincidence—certainly
+approaches the miraculous. We can no longer, then,
+properly speak of “the snowy poles of moonless Mars,” though
+it does still remain moonless to all but the most powerful
+telescopes in the world, for these bodies are the very smallest
+known in the system. They present no visible disks to measure,
+but look like the faintest of points of light, and their size
+is only to be guessed at from their brightness. Professor Pickering
+has carried on an interesting investigation of them. His
+method depended in part on getting holes of such smallness
+made in a plate of metal that the light coming through them
+would be comparable with that of the Martial moons in the
+telescope. It was found almost impossible to command the skill
+to make these holes small enough, though one of the artists employed
+had already distinguished himself by drilling a hole
+through a fine cambric needle <em>lengthwise</em>, so as to make a tiny
+steel tube of it. When the difficulty was at last overcome, the
+satellites were found to be less than ten miles in diameter, and
+a just impression both of their apparent size and light may be
+gathered from the statement that either roughly corresponds to
+that which would be given by a human hand held up at Washington,
+and viewed from Boston, Massachusetts, a distance of
+four hundred miles.</p>
+
+<p><span class="pagenum" id="Page_133">133</span></p>
+
+<p>We approach now the only planet in which man is certainly
+known to exist, and which ought to have an interest for us superior
+to any which we have yet seen, for it is our own. We are
+voyagers on it through space, it has been said, as passengers on a
+ship, and many of us have never thought of any part of the vessel
+but the cabin where we are quartered. Some curious passengers
+(these are the geographers) have visited the steerage, and some
+(the geologists) have looked under the hatches, and yet it remains
+true that those in one part of our vessel know little, even
+now, of their fellow-voyagers in another. How much less, then,
+do most of us know of the ship itself, for we were all born on it,
+and have never once been off it to view it from the outside!</p>
+
+<p>No world comes so near us in the aerial ocean as the moon;
+and if we desire to view our own earth as a planet, we may
+put ourselves in fancy in the place of a lunar observer. “Is
+it inhabited?” would probably be one of the first questions
+which he would ask, if he had the same interest in us that we
+have in him; and the answer to this would call out all the
+powers of the best telescopes such as we possess.</p>
+
+<p>An old author, Fontenelle, has put in the mouth of an imaginary
+spectator a lively description of what would be visible in
+twenty-four hours to one looking down on the earth as it turned
+round beneath him. “I see passing under my eyes,” he says,
+“all sorts of faces,—white and black and olive and brown.
+Now it’s hats, and now turbans, now long locks and then shaven
+crowns; now come cities with steeples, next more with tall, crescent-capped
+minarets, then others with porcelain towers; now
+great desolate lands, now great oceans, then dreadful deserts,—in
+short, all the infinite variety the earth’s surface bears.” The
+truth is, however, that, looking at the earth from the moon, the
+largest moving animal, the whale or the elephant, would be utterly
+beyond our ken; and it is questionable whether the largest
+ship on the ocean would be visible, for the popular idea as to<span class="pagenum" id="Page_134">134</span>
+the magnifying power of great telescopes is exaggerated. It is
+probable that under any but extraordinary circumstances our
+lunar observer, with our best telescopes, could not bring the
+earth within less than an apparent distance of five hundred
+miles; and the reader may judge how large a moving object
+must be to be seen, much less recognized, by the naked eye
+at such a distance.</p>
+
+<p>Of course, a chief interest of the supposition we are making
+lies in the fact that it will give us a measure of our own ability
+to discover evidences of life in the moon, if there are any such
+as exist here; and in this point of view it is worth while to
+repeat, that scarcely any temporary phenomenon due to human
+action could be even telescopically visible from the moon under
+the most favoring circumstances. An army such as Napoleon
+led to Russia might conceivably be visible if it moved in a dark
+solid column across the snow. It is barely possible that such
+a vessel as one of the largest ocean steamships might be seen,
+under very favorable circumstances, as a moving dot; and it is
+even quite probable that such a conflagration as the great fire of
+Chicago would be visible in the lunar telescope, as something
+like a reddish star on the night side of our planet; but this is
+all in this sort that could be discerned.</p>
+
+<p>By making minute maps, or, still better, photographs, and
+comparing one year with another, much however might have
+been done by our lunar observer during this century. In its
+beginning, in comparison to the vast forests which then covered
+the North American continent, the cultivated fields along its
+eastern seaboard would have looked to him like a golden fringe
+bordering a broad mantle of green; but now he would see that
+the golden fringe has encroached upon the green farther back
+than the Mississippi, and he would gather his best evidence
+of change from the fact (surely a noteworthy one) that the
+people of the United States have altered the features of the<span class="pagenum" id="Page_135">135</span>
+world during the present century to a degree visible in another
+planet!</p>
+
+<p>Our observer would probably be struck by the moving panorama
+of forests, lakes, continents, islands, and oceans, successively
+gliding through the field of view of his telescope as the
+earth revolved; but, travelling along beside it on his lunar
+station, he would hardly appreciate its actual flight through
+space, which is an easy thing to describe in figures, and a hard
+one to conceive. If we look up at the clock, and as we watch
+the pendulum recall that we have moved about nineteen miles
+at every beat, or in less than three minutes, over a distance
+greater than that which divides New York from Liverpool, we
+still probably but very imperfectly realize the fact that (dropping
+all metaphor) the earth is really a great projectile, heavier than
+the heaviest of her surface rocks, and traversing space with a
+velocity of over sixty times that of the cannon-ball. Even the
+firing of a great gun with a ball weighing one or two hundred
+pounds is, to the novice at least, a striking spectacle. The massive
+iron sphere is hoisted into the gun, the discharge comes, the
+ground trembles, and, as it seems, almost in the same instant,
+a jet rises where the ball has touched the water far away.
+The impression of immense velocity and of a resistless capacity
+of destruction in that flying mass is irresistible, and justifiable
+too: but what is this ball to that of the earth, which is a globe
+counting eight thousand miles in diameter, and weighing about
+six thousand millions of millions of millions of tons; which, if our
+cannon-ball were flying ahead a mile in advance of its track,
+would overtake it in less than the tenth part of a second; and
+which carries such a potency of latent destruction and death in
+this motion, that if it were possible instantly to arrest it, then,
+in that instant, “earth and all which it inherits would dissolve”
+and pass away in vapor?</p>
+
+<p>Our turning sphere is moving through what seems to be all<span class="pagenum" id="Page_136">136</span>
+but an infinite void, peopled only by wandering meteorites, and
+where warmth from any other source than the sun can scarcely
+be said to exist; for it is important to observe that whether the
+interior be molten or not, we get next to no heat from it. The
+cold of outer space can only be estimated in view of recent
+observations as at least four hundred degrees Fahrenheit below
+zero (mercury freezes at thirty-nine degrees below), and it is the
+sun which makes up the difference of all these lacking hundreds
+of degrees to us, but indirectly, and not in the way that we
+might naturally think, and have till very lately thought; for
+our atmosphere has a great deal to do with it beside the direct
+solar rays, allowing more to come in than to go out, until
+the temperature rises very much higher than it would were
+there no air here. Thus, since it is this power in the atmosphere
+of storing the heat which makes us live, no less than the sun’s
+rays themselves, we see how the temperature of a planet may
+depend on considerations quite beside its distance from the sun;
+and when we discuss the possibility of life in other worlds, we
+shall do well to remember that Saturn may be possibly a warm
+world, and Mercury conceivably a cold one.</p>
+
+<p>We used to be told that this atmosphere extended forty-five
+miles above us, but later observation proves its existence at a
+height of many times this; and a remarkable speculation, which
+Dr. Hunt strengthens with the great name of Newton, even
+contemplates it as extending in ever-increasing tenuity until it
+touches and merges in the atmosphere of other worlds.</p>
+
+<div id="ip_65" class="figcenter" style="max-width: 32em;">
+  <img src="images/i_137.jpg" alt="" />
+  <div class="caption"><p>FIG. 65.—THE MOON.</p>
+
+<p class="smaller">(FROM A PHOTOGRAPH BY L. M. RUTHERFURD, 1873, PUBLISHED BY O. G. MASON.)</p></div></div>
+
+<p>But if we begin to talk of things new and old which interest
+us in our earth as a planet, it is hard to make an end. Still we
+may observe that it is the very familiarity of some of these
+which hinders us from seeing them as the wonders they really
+are. How has this familiarity, for instance, made commonplace
+to us not only the wonderful fact that the fields and forests, and
+the apparently endless plain of earth and ocean, are really parts<span class="pagenum" id="Page_139">139</span>
+of a great globe which is turning round (for this rotation we
+all are familiar with), but the less appreciated miracle that we
+are all being hurled through space with an immensely greater
+speed than that of the rotation itself. It needs the vision of a
+poet to see this daily miracle with new eyes; and a great poet
+has described it for us, in words which may vivify our scientific
+conception. Let us recall the prologue to “Faust,” where the
+archangels are praising the works of the Lord, and looking at
+the earth, not as we see it, but down on it, from heaven, as it
+passes by, and notice that it is precisely this miraculous swiftness,
+so insensible to us, which calls out an angel’s wonder.</p>
+
+<div class="poetry-container">
+<div class="poetry">
+  <div class="stanza">
+    <div class="verse indentq">“And swift and swift beyond conceiving</div>
+    <div class="verse indent0">The splendor of the world goes round,</div>
+    <div class="verse indent0">Day’s Eden-brightness still relieving</div>
+    <div class="verse indent0">The awful Night’s intense profound.</div>
+    <div class="verse indent0">The ocean tides in foam are breaking,</div>
+    <div class="verse indent0">Against the rocks’ deep bases hurled,</div>
+    <div class="verse indent0">And both, the spheric race partaking,</div>
+    <div class="verse indent0">Eternal, swift, are onward whirled.”<a id="FNanchor_5" href="#Footnote_5" class="fnanchor">5</a></div>
+  </div>
+</div>
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_5" href="#FNanchor_5" class="fnanchor">5</a> Bayard Taylor’s translation.</p>
+
+</div>
+
+<p class="in0">So, indeed, might an angel see it and describe it!</p>
+
+<div class="tb">* * * * *</div>
+
+<p>We may have been already led to infer that there is a kind
+of evolution in the planets’ life, which we may compare, by a
+not wholly fanciful analogy, to ours; for we have seen worlds
+growing into conditions which may fit them for habitability,
+and again other worlds where we may surmise, or may know,
+that life has come. To learn of at least one which has completed
+the analogy, by passing beyond this term to that where all life
+has ceased, we need only look on the moon.</p>
+
+<div class="tb">* * * * *</div>
+
+<p>The study of the moon’s surface has been continued now
+from the time of Galileo, and of late years a whole class of
+competent observers has been devoted to it, so that astronomers
+engaged in other branches have oftener looked on this as a field<span class="pagenum" id="Page_140">140</span>
+for occasional hours of recreation with the telescope than made
+it a constant study. I can recall one or two such hours in earlier
+observing days, when, seated alone under the overarching iron
+dome, the world below shut out, and the world above opened,
+the silence disturbed by no sound but the beating of the equatorial
+clock, and the great telescope itself directed to some hill
+or valley of the moon, I have been so lost in gazing that it
+seemed as though a look through this, the real magic tube, had
+indeed transported me to the surface of that strange alien world.
+Fortunately for us, the same spectacle has impressed others with
+more time to devote to it and more ability to render it, so that
+we not only have most elaborate maps of the moon for the professional
+astronomer, but abundance of paintings, drawings, and
+models, which reproduce the appearance of its surface as seen
+in powerful telescopes. None of the latter class deserves more
+attention than the beautiful studies of Messrs. Nasmyth and
+Carpenter, who prepared at great labor very elaborate and, in
+general, very faithful models of parts of its surface, and then
+had them photographed under the same illumination which fell
+on the original; and I wish to acknowledge here the special
+indebtedness of this part of what I have to lay before the
+reader to their work, from which the following illustrations are
+chiefly taken.</p>
+
+<p>Let us remember that the moon is a little over twenty-one
+hundred miles in diameter; that it weighs, bulk for bulk, about
+two-thirds what the earth does, so that, in consequence of this
+and its smaller size, its total weight is only about one-eightieth
+of that of our globe; and that, the force of gravity at its surface
+being only one-sixth what it is here, eruptive explosions can
+send their products higher than in our volcanoes. Its area is
+between four and five times that of the United States, and its
+average distance is a little less than two hundred and forty
+thousand miles.</p>
+
+<p><span class="pagenum" id="Page_141">141</span></p>
+
+<div id="ip_66" class="figcenter" style="max-width: 29em;">
+  <img src="images/i_141.jpg" alt="" />
+  <div class="caption">FIG. 66.—THE FULL MOON.</div></div>
+
+<p><span class="pagenum" id="Page_143">143</span></p>
+
+<p>This is very little in comparison with the great spaces we
+have been traversing in imagination; but it is absolutely very
+large, and across it the valleys and mountains of this our nearest
+neighbor disappear, and present to the naked eye only the vague
+lights and shades known to us from childhood as “the man in
+the moon,” and which were the puzzle of the ancient philosophers,
+who often explained them as reflections of the earth
+itself, sent back to us from the moon as from a mirror. It, at
+any rate, shows that the moon always turns the same face toward
+us, since we always see the same “man,” and that there must
+be a back to the moon which we never behold at all; and, in
+fact, nearly half of this planet does remain forever hidden from
+human observation.</p>
+
+<p>The “man in the moon” disappears when we are looking in
+a telescope, because we are then brought so near to details that
+the general features are lost; but he can be seen in any photograph
+of the full moon by viewing it at a sufficient distance, and
+making allowance for the fact that the contrasts of light and
+shade appear stronger in the photograph than they are in reality.
+If the small full moon given in <a href="#ip_66">Fig. 66</a>, for instance, be looked at
+from across a room, the naked-eye view will be recovered, and
+its connection with the telescopic ones better made out. The
+best time for viewing the moon, however, is not at the full,
+but at the close of the first quarter; for then we see, as in
+this beautiful photograph (<a href="#ip_65">Fig. 65</a>) by Mr. Rutherfurd, that
+the sunlight, falling slantingly on it, casts shadows which bring
+out all the details so that we can distinguish many of them
+even here,—this photograph, though much reduced, giving the
+reader a better view than Galileo obtained with his most powerful
+telescope. The large gray expanse in the lower part is the
+Mare Serenitatis, that on the left the Mare Crisium, and so on;
+these “seas,” as they were called by the old observers, being no
+seas at all in reality, but extended plains which reflect less light<span class="pagenum" id="Page_144">144</span>
+than other portions, and which with higher powers show an
+irregular surface. Most of the names of the main features of
+the lunar surface were bestowed by the earlier observers in the
+infancy of the telescope, when her orb</p>
+
+<div class="poetry-container">
+<div class="poetry">
+  <div class="stanza">
+    <div class="verse indentq">“Through optic glass the Tuscan artist ‘viewed’</div>
+    <div class="verse indent0">At evening from the top of Fiesole</div>
+    <div class="verse indent0">Or in Valdarno, to descry new lands,</div>
+    <div class="verse indent0">Rivers, or mountains in her spotty globe.”</div>
+  </div>
+</div>
+</div>
+
+<p>Mountains there are, like the chain of the lunar Apennines,
+which the reader sees a little below the middle of the moon, and
+to the right of the Mare Serenitatis, and where a good telescope
+will show several thousand distinct summits. Apart from the
+mountain chains, however, the whole surface is visibly pitted
+with shallow, crater-like cavities, which vary from over a hundred
+miles in diameter to a few hundred yards or less, and
+which, we shall see later, are smaller sunken plains walled
+about with mountains or hills.</p>
+
+<p>One of the most remarkable, of these is Tycho, here seen on
+the photograph of the full moon (<a href="#ip_66">Fig. 66</a>), from which radiating
+streaks go in all directions over the lunar surface. These streaks
+are a feature peculiar to the moon (at least we know of nothing
+to which they can be compared on the earth), for they run
+through mountain and valley for hundreds of miles without any
+apparent reference to the obstacles in their way, and it is clear
+that the cause is a deep-seated one. This cause is believed by
+our authors to be the fact that the moon was once a liquid sphere
+over which a hard crust formed, and that in subsequent time the
+expansion of the interior before solidification cracked the shell as
+we see. The annexed figure (<a href="#ip_67">Fig. 67</a>) is furnished by them to
+illustrate their theory, and to show the effects of what they
+believe to be an analogous experiment, <i xml:lang="la" lang="la">in minimis</i>, to what Nature
+has performed on the grandest scale; for the photograph
+shows a glass globe actually cracked by the expansion of an<span class="pagenum" id="Page_147">147</span>
+enclosed fluid (in this case water), and the resemblance of the
+model to the photograph of the full moon on page 141 is
+certainly a very interesting one.</p>
+
+<div id="ip_67" class="figcenter" style="max-width: 29em;">
+  <img src="images/i_145.jpg" alt="" />
+  <div class="caption">FIG. 67.—GLASS GLOBE, CRACKED.</div></div>
+
+<p>We are able to see from this, and from the multitude of
+craters shown even on the general view, where the whole face
+of our satellite is pit-marked, that eruptive action has been more
+prominent on the moon in ages past than on our own planet,
+and we are partly prepared for what we see when we begin to
+study it in detail.</p>
+
+<p>We may select almost any part of the moon’s surface for this
+nearer view, with the certainty of finding something interesting.
+Let us choose, for instance, on the photograph of the half-full
+moon (<a href="#ip_65">Fig. 65</a>), the point near the lower part of the Terminator
+(as the line dividing light from darkness is called) where a minute
+sickle of light seems to invade the darkness, and let us apply in
+imagination the power of a large telescope to it. We are brought
+at once considerably within a thousand miles of the surface,
+over which we seem to be suspended, everything lying directly
+beneath us as in a bird’s-eye view, and what we see is the
+remarkable scene shown in <a href="#ip_68">Fig. 68</a>.</p>
+
+<p>We have before us such a wealth of detail that the only trouble
+is to choose what to speak of where every point has something to
+demand attention, and we can only give here the briefest reference
+to the principal features. The most prominent of these is
+the great crater “Plato,” which lies in the lower right-hand part
+of the cut. It will give the reader an idea of the scale of things
+to state that the diameter of its ring is about seventy miles; so
+that he will readily understand that the mountains surrounding
+it may average five to six thousand feet in height, as they do.
+The sun is shining from the left, and, being low, casts long
+shadows, so that the real forms of the mountains on one side
+are beautifully indicated by these shadows, where they fall on
+the floor of the crater. In the lower part of the mountain wall<span class="pagenum" id="Page_148">148</span>
+there has been a land-slide, as we see by the fragments that
+have rolled down into the plain, and of which a trace can be
+observed in our engraving. The whole is quite unlike most
+terrestrial craters, however, not only in its enormous size, but
+in its proportions; for the floor is not precipitous, but flat, or
+partaking of the general curvature of the lunar surface, which
+it sinks but little below. I have watched with interest in the
+telescope streaks and shades on the floor of Plato, not shown in
+our cut; for here some have suspected evidences of change, and
+fancied a faint greenish tint, as if due to vegetation, but it is
+probably fancy only. Notice the number of small craters
+around the big one, and everywhere on the plate, and then
+look at the amazingly rugged and tumbled mountain heaps on
+the left (the lunar Alps), cut directly through by a great valley
+(the valley of the Alps), which is at the bottom about six
+miles wide and extraordinarily flat,—flatter and smoother even
+than our engraving shows it, and looking as though a great
+engineering work, rather than an operation of Nature, were in
+question. Above this the mountain shadows are cast upon a
+wide plain, in which are both depressed pits with little mountain
+(or rather hill) rings about them, and extraordinary peaks, one
+of which, Pico (above the great crater), starts up abruptly to
+the height of eight thousand feet, a lunar Matterhorn.</p>
+
+<p>If Mars were as near as the moon, we should see with the
+naked eye clouds passing over its face; and that we never do
+see these on the moon, even with the telescope, is itself a proof
+that none exist there. Now, this absence of clouds, or indeed
+of any evidence of moisture, is confirmed by every one of the
+nearer views like those we are here getting. We might return
+to this region with the telescope every month of our lives without
+finding one indication of vapor, of moisture, or even of air;
+and from a summit like Pico, could we ascend it, we should
+look out on a scene of such absolute desolation as probably no<span class="pagenum" id="Page_151">151</span>
+earthly view could parallel. If, as is conceivable, these plains
+were once covered with verdure, and the abode of living creatures,
+verdure and life exist here no longer, and over all must
+be the silence of universal death. But we must leave it for
+another scene.</p>
+
+<div id="ip_68" class="figcenter" style="max-width: 32em;">
+  <img src="images/i_149.jpg" alt="" />
+  <div class="caption">FIG. 68.—PLATO AND THE LUNAR ALPS.</div></div>
+
+<p>South of Plato extends for many hundred miles a great plain,
+which from its smoothness was thought by the ancient observers
+to be water, and was named by them the “Imbrian Sea,” and
+this is bounded on the south and west by a range of mountains—the
+“lunar Apennines” (<a href="#ip_69">Fig. 69</a>)—which are the most striking
+on our satellite. They are visible even with a spy-glass,
+looking then like bread-crumbs ranged upon a cloth, while with
+a greater power they grow larger and at the same time more
+chaotic. As we approach nearer, we see that they rise with a
+comparatively gradual slope, to fall abruptly, in a chain of
+precipices that may well be called tremendous, down to the
+plain below, across which their shadows are cast. Near their
+bases are some great craters of a somewhat different type from
+Plato, and our illustration represents an enlarged view of a
+part of this Apennine chain, of the great crater Archimedes,
+and of its companions Aristillus and Autolycus.</p>
+
+<p>Our engraving will tell, more than any description, of the
+contrast of the tumbled mountain peaks with the level plain
+from which they spring,—a contrast for which we have scarcely
+a terrestrial parallel, though the rise of the Alps from the plains
+of Lombardy may suggest an inadequate one. The Sierra
+Nevadas of California climb slowly up from the coast side, to
+descend in great precipices on the east, somewhat like this; but
+the country at their feet is irregular and broken, and their
+highest summits do not equal those before us, which rise to
+seventeen or eighteen thousand feet, and from one of which
+we should look out over such a scene of desolation as we
+can only imperfectly picture to ourselves from any experience<span class="pagenum" id="Page_152">152</span>
+of a terrestrial desert. The curvature of the moon’s surface
+is so much greater than ours, that it would hide the spurs
+of hills which buttress the southern slopes of Archimedes, leaving
+only the walls of the great mountain ring visible in the
+extremest horizon, while between us and them would extend
+what some still maintain to have been the bed of an ancient
+lunar ocean, though assuredly no water exists there now.</p>
+
+<p>Among the many fanciful theories to account for the forms
+of the ringed plains, one (and this is from a man of science
+whose ideas are always original) invokes the presence of water.
+According to it, these great plains were once ocean beds, and
+in them worked a coral insect, building up lunar “atolls” and
+ring-shaped submarine mountains, as the coral polyp does here.
+The highest summits of the great rings thus formed were then
+low islands, just “a-wash” with the waves of the ancient lunar
+sea, and, for aught we know, green with feathery palms. Then
+came (in the supposition in question) a time when the ocean
+dried up, and the mountains were left standing, as we see,
+in rings, after the cause of their formation was gone. If it be
+asked where the water went to, the answer is not very obvious
+on the old theories; but those who believe in them point to the
+extraordinary cracks in the soil, like those our engraving shows,
+as chasms and rents, by which the vanished seas, and perhaps
+also the vanished air, have been absorbed into the interior.</p>
+
+<div id="ip_69" class="figcenter" style="max-width: 29em;">
+  <img src="images/i_153.jpg" alt="" />
+  <div class="caption">FIG. 69.—THE LUNAR APENNINES: ARCHIMEDES.</div></div>
+
+<p>If there was indeed such an ancient ocean, it would have
+washed the very feet of the precipices on whose summits we
+are in imagination standing, and below us their recesses would
+have formed harbors which fancy might fill with commerce,
+and cities in which we might picture life and movement where
+all is now dead. It need hardly be said that no telescope has
+ever revealed their existence (if such ruins, indeed, there are),
+and it may be added that the opinion of geologists is, as a
+whole, unfavorable to the presence of water on the moon, even<span class="pagenum" id="Page_155">155</span>
+in the past, from the absence of any clear evidence of erosive
+action; but perhaps we are not yet entitled to speak on these
+points with certainty, and are not forbidden to believe that
+water may have existed here in the past by any absolute testimony
+to the contrary. The views of those who hold the larger
+portion of the lunar craters to have been volcanic in their formation
+are far more probable; and perhaps as simple an evidence
+of the presumption in their favor as we can give is directly to
+compare such a lunar region as this, the picture of which was
+made for us from a model, with a similar model made from
+some terrestrial volcanic region. Here (<a href="#ip_70">Fig. 70</a>) is a photograph
+of such a modelled plan of the country round the Bay of Naples,
+showing the ancient crater of Vesuvius and its central cone,
+with other and smaller craters along the sea. Here, of course,
+we <em>know</em> that the forms originated in volcanic action, and a comparison
+of them with our moon-drawing is most interesting. To
+return to our Apennine region (<a href="#ip_69">Fig. 69</a>), we must admit, however,
+when we consider the vast size of these things (Archimedes
+is fifty miles in diameter), that they are very different in proportion
+from our terrestrial craters, and that numbers of them
+present no central cone whatever; so that if some of them seem
+clearly eruptive, there are others to which we have great difficulties
+in making these volcanic theories apply. Let us look,
+for instance, at still another region (<a href="#ip_71">Fig. 71</a>). It lies rather
+above the centre of the full moon, and may be recognized also
+on the Rutherfurd photograph; and it consists of the group of
+great ring-plains, three of which form prominent figures in
+our cut.</p>
+
+<p>Ptolemy (the lower of these in the drawing) is an example of
+such a plain, whose diameter reaches to about one hundred and
+fifteen miles, so that it encloses an area of nearly eight thousand
+square miles (or about that of the State of Massachusetts), within
+which there is no central cone or point from which eruptive<span class="pagenum" id="Page_156">156</span>
+forces appear to have acted, except the smaller craters it encloses.
+On the south we see a pass in the mountain wall opening
+into the neighboring ring-plain of Alphonsus, which is only
+less in size; and south of this again is Arzachel, sixty-six miles
+in diameter, surrounded with terraced walls, rising in one place
+to a height greater than that of Mont Blanc, while the central
+cone is far lower. The whole of the region round about, though
+not the roughest on the moon, is rough and broken in a way beyond
+any parallel here, and which may speak for itself; but
+perhaps the most striking of the many curious features—at
+least the only one we can pause to examine—is what is called
+“The Railway,” an almost perfectly straight line, on one side of
+which the ground has abruptly sunk, leaving the undisturbed
+part standing like a wall, and forming a “fault,” as geologists
+call it. This is the most conspicuous example of its kind in the
+moon, but it is only one of many evidences that we are looking
+at a world whose geological history has been not wholly unlike
+our own. But the moon contains, as has been said, but the one-eightieth
+part of the mass of our globe, and has therefore cooled
+with much greater rapidity, so that it has not only gone through
+the epochs of our own past time, but has in all probability already
+undergone experiences which for us lie far in the future;
+and it is hardly less than justifiable language to say that we are
+beholding here in some respects what the face of our world may
+be when ages have passed away.</p>
+
+<div id="ip_70" class="figcenter" style="max-width: 29em;">
+  <img src="images/i_157.jpg" alt="" />
+  <div class="caption">FIG. 70.—VESUVIUS AND NEIGHBORHOOD OF NAPLES.</div></div>
+
+<p>To see this more clearly, we may consider that in general we
+find that the early stages of cosmical life are characterized by
+great heat; a remark of the truth of which the sun itself furnishes
+the first and most obvious illustration. Then come
+periods which we appear to have seen exemplified in Jupiter,
+where the planet is surrounded by volumes of steam-like vapor,
+through which we may almost believe we recognize the dull
+glow of not yet extinguished fires; then times like those which<span class="pagenum" id="Page_159">159</span>
+our earth passed through before it became the abode of man;
+and then the times in which human history begins. But if this
+process of the gradual loss of heat go on indefinitely, we must
+yet come to still another era, when the planet has grown too
+cold to support life, as it was before too hot; and this condition,
+in the light of some very recent investigations, it seems probable
+we have now before us on the moon.</p>
+
+<p>We have, it is true, been taught until very lately that the
+side of the moon turned sunward would grow hotter and hotter
+in the long lunar day, till it reached a temperature of two hundred
+to three hundred degrees Fahrenheit, and that in the
+equally long lunar night it would fall as much as this below
+zero. But the evidence which was supposed to support this
+conclusion as to the heat of the lunar day is not supported by
+recent experiments of the writer; and if these be trustworthy,
+certain facts appear to him to show that the temperature of the
+moon’s surface, even under full perpetual sunshine, must be
+low,—and this because of the absence of air there to keep the
+stored sun-heat from being radiated away again into space.</p>
+
+<p>As we ascend the highest terrestrial mountains, and get partly
+above our own protecting blanket of air, things do not grow
+hotter and hotter, but colder and colder; and it seems contrary
+to the teachings of common sense to believe that if we could
+ascend higher yet, where the air ceases altogether, we should
+not find that it grew colder still. But this last condition (of airlessness)
+is the one which does prevail beyond a doubt in the
+moon, on whose whole surface, then, there must be (unless there
+are sources of internal heat of which we know nothing) conditions
+of temperature which are an exaggeration of those we experience
+on the summit of a very lofty mountain, where we
+have the curious result that the skin may be burned under the
+solar rays, while we are shivering at the same time in what the
+thermometer shows is an arctic cold.</p>
+
+<p><span class="pagenum" id="Page_160">160</span></p>
+
+<p>We have heard of this often; but a personal experience so
+impressed the fact on me that I will relate it for the benefit of
+the reader, who may wish to realize to himself the actual conditions
+which probably exist in the airless lunar mountains and
+plains we are looking at. He cannot go there; but he may go
+if he pleases, as I have done, to the waterless, shadeless waste
+which stretches at the eastern slope of the Sierra Nevadas (a
+chain almost as high and steep as the lunar Apennines), and live
+some part of July and August in this desert, where the thermometer
+rises occasionally to one hundred and ten degrees in
+the shade, and his face is tanned till it can tan no more, and he
+appears to himself to have experienced the utmost in this way
+that the sun can do.</p>
+
+<p>The sky is cloudless, and the air so clear that all idea of the
+real distance and size of things is lost. The mountains, which
+rise in tremendous precipices above him, seem like moss-covered
+rocks close at hand, on the tops of which, here and there, a white
+cloth has been dropped; but the “moss” is great primeval
+forests, and the white cloths large isolated snow-fields, tantalizing
+the dweller in the burning desert with their delusive nearness.
+When I climbed the mountains, at an altitude of ten
+thousand feet I already found the coolness delicious, but at the
+same time (by the strange effect I have been speaking of) the
+skin began to burn, as though the seasoning in the desert
+counted for nothing at all; and as the air grew thinner and
+thinner while I mounted still higher and higher, though the
+thermometer fell, every part of the person exposed to the solar
+rays presented the appearance of a recent severe burn from an
+actual fire,—and a really severe burn it was, as I can testify,—and
+yet all the while around us, under this burning sun and
+cloudless sky, reigned a perpetual winter which made it hard
+to believe that torrid summer still lay below. The thinner the
+air, then, the colder it grows, even where we are exposed to the<span class="pagenum" id="Page_163">163</span>
+sun, and the lower becomes the reading of the thermometer.
+Now, by means of suitable apparatus, it was sought by the
+writer to determine, while at this elevation of fifteen thousand
+feet, <em>how</em> great the fall of temperature would be if the thin air
+there could be removed altogether; and the result was that the
+thermometer would under such circumstances fall, at any rate,
+below zero in the full sunshine.</p>
+
+<div id="ip_71" class="figcenter" style="max-width: 29em;">
+  <img src="images/i_161.jpg" alt="" />
+  <div class="caption">FIG. 71.—PTOLEMY AND ARZACHEL.</div></div>
+
+<p>Of course, all this applies indirectly to the moon, above
+whose surface (if these inferences be correct) the mercury in
+the bulb of a thermometer would probably freeze and never
+melt again during the lunar day (and still less during the lunar
+night),—a conclusion which has been reached through other
+means by Mr. Ericsson,—and whose surface itself cannot be very
+greatly warmer. Other and direct measures of the lunar heat
+are still in progress while this is being written, but their probable
+result seems to be already indicated: it is that the moon’s
+surface, even in perpetual sunshine, must be forever cold. Just
+how cold, is still doubtful; and it is not yet certain whether ice,
+if once formed there, could ever melt.</p>
+
+<p>Here (<a href="#ip_72">Fig. 72</a>) is one more scene from the almost unlimited
+field the lunar surface affords.</p>
+
+<p>The most prominent things in the landscape before us are
+two fine craters (Mercator and Campanus), each over thirty
+miles in diameter; but we have chosen this scene for remark
+rather on account of the great crack or rift which is seen in the
+upper part, and which cuts through plain and mountain for a
+length of sixty miles. Such cracks are counted by hundreds on
+the moon, where they are to be seen almost everywhere; and
+other varieties, in fact, are visible on this same plate, but we will
+not stop to describe them. This one varies in width from an
+eighth of a mile to a mile; and though we cannot see to the
+bottom of it, others are known to be at least eight miles deep,
+and may be indefinitely deeper.</p>
+
+<p><span class="pagenum" id="Page_164">164</span></p>
+
+<p>The edge of a cliff on the earth commonly gets weather-worn
+and rounded; but here the edge is sharp, so that a traveller along
+the lunar plains would come to the very brink of this tremendous
+chasm before he had any warning of its existence. It is
+usually thus with all such rifts; and the straightness and sharpness
+of the edge in these cases suggest the appearance of an ice-crack
+to the observer. I do not mean to assert that there is
+more than a superficial resemblance. I do not write as a geologist;
+but in view of what we have just been reading of the lunar
+cold, we may ask ourselves whether, if water ever did exist here,
+we should not expect to find perpetual ice, not necessarily glittering,
+but covered, perhaps, with the deposits of an air laden
+with the dust-products of later volcanic eruptions, or even covered
+in after ages, when the air has ceased from the moon, with
+the slow deposit of meteoric dust during millions of years of
+windless calm. What else can we think will become of the
+water on our own earth if it be destined to pass through such
+an experience as we seem to see prophesied in the condition of
+our dead satellite?</p>
+
+<p>The reader must not understand me as saying that there is
+ice on the moon,—only that there is not improbably perpetual
+ice there now <em>if</em> there ever was water in past time; and he is not
+to suppose that to say this is in any way to deny what seems
+the strong evidence of the existence of volcanic action everywhere,
+for the two things may well have existed in successive
+ages of our satellite’s past, or even have both existed together,
+like Hecla, within our own arctic snows; and if no sign of any
+still active lunar volcano has been discovered, we appear to read
+the traces of their presence in the past none the less clearly.</p>
+
+<p>I remember that at one time, when living on the lonely upper
+lava-wastes of Mount Etna, which are pitted with little craters,
+I grew acquainted with so many a chasm and rent filled with
+these, that the dreary landscape appeared from above as if a bit<span class="pagenum" id="Page_167">167</span>
+of the surface of the moon I looked up at through the telescope
+had been brought down beside me.</p>
+
+<div id="ip_72" class="figcenter" style="max-width: 29em;">
+  <img src="images/i_165.jpg" alt="" />
+  <div class="caption">FIG. 72.—MERCATOR AND CAMPANUS.</div></div>
+
+<p>I remember, too, that as I studied the sun there, and watched
+the volcanic outbursts on its surface, I felt that I possibly
+embraced in a threefold picture as many stages in the history of
+planetary existence, through all of which this eruptive action was
+an agent,—above in the primal energies of the sun; all around
+me in the great volcano, black and torn with the fires that still
+burn below, and whose smoke rose over me in the plume that
+floated high up from the central cone; and finally in this last
+stage in the moon, which hung there pale in the daylight sky,
+and across whose face the vapors of the great terrestrial volcano
+drifted, but on whose own surface the last fire was extinct.</p>
+
+<p>We shall not get an adequate idea of it all, unless we add to
+our bird’s-eye views one showing a chain of lunar mountains as
+they would appear to us if we saw them, as we do our own Alps
+or Apennines, from about their feet; and such a view <a href="#ip_74">Fig. 74</a>
+affords us. In the barren plain on the foreground are great
+rifts such as we have been looking at from above, and smaller
+craters, with their extinct cones; while beyond rise the mountains,
+ghastly white in the cold sunshine, their precipices
+crowned by no mountain fir or cedar, and softened by no
+intervening air to veil their nakedness.</p>
+
+<p>If the reader has ever climbed one of the highest Alpine
+peaks, like those about Monte Rosa or the Matterhorn, and
+there waited for the dawn, he cannot but remember the sense
+of desolation and strangeness due to the utter absence of everything
+belonging to man or his works or his customary abode,
+above all which he is lifted into an upper world, so novel and,
+as it were, so unhuman in its features, that he is not likely to
+have forgotten his first impression of it; and this impression
+gives the nearest but still a feeble idea of what we see with the
+telescope in looking down on such a colorless scene, where too<span class="pagenum" id="Page_168">168</span>
+no water bubbles, no tree can sigh in the breeze, no bird can
+sing,—the home of silence.</p>
+
+<div id="ip_73" class="figcenter" style="max-width: 20em;">
+  <img src="images/i_168.jpg" alt="" />
+  <div class="caption">FIG. 73.—WITHERED HAND.</div></div>
+
+<p>But here, above it, hangs a world in the sky, which we
+should need to call in color to depict, for it is green and yellow
+with the forests and the harvest-fields that overspread its continents,
+with emerald islands studding its gray oceans, over all
+of which sweep the clouds that bring the life-giving rain. It is
+our own world, which lights up the dreary lunar night, as the
+moon does ours.</p>
+
+<p><span class="pagenum" id="Page_169">169</span></p>
+
+<div id="ip_74" class="figcenter" style="max-width: 38em;">
+  <img src="images/i_169.jpg" alt="" />
+  <div class="caption">FIG. 74.—IDEAL LUNAR LANDSCAPE AND EARTH-SHINE.</div></div>
+
+<p><span class="pagenum" id="Page_171">171</span></p>
+
+<p>The signs of age are on the moon. It seems pitted, torn, and
+rent by the past action of long-dead fires, till its surface is like a
+piece of porous cinder under the magnifying-glass,—a burnt-out
+cinder of a planet, which rolls through the void like a ruin of
+what has been; and, more significant still, this surface is wrinkled
+everywhere, till the analogy with an old and shrivelled face
+or hand or fruit (Figs. <a href="#ip_73">73</a> and <a href="#ip_75">75</a>), where the puckered skin is
+folded about a shrunken centre, forces itself on our attention,
+and suggests a common cause,—a something underlying the
+analogy, and making it more than a mere resemblance.</p>
+
+<div id="ip_75" class="figcenter" style="max-width: 20em;">
+  <img src="images/i_171.jpg" alt="" />
+  <div class="caption">FIG. 75.—WITHERED APPLE.</div></div>
+
+<p>The moon, then, is dead; and if it ever was the home of a
+race like ours, that race is dead too. I have said that our New
+Astronomy modifies our view of the moral universe as well as of
+the physical one; nor do we need a more pregnant instance than<span class="pagenum" id="Page_172">172</span>
+in this before us. In these days of decay of old creeds of the
+eternal, it has been sought to satisfy man’s yearning toward it
+by founding a new religion whose god is Humanity, and whose
+hope lies in the future existence of our own race, in whose collective
+being the individual who must die may fancy his aims
+and purpose perpetuated in an endless progress. But, alas for
+hopes looking to this alone! we are here brought to face the
+solemn thought that, like the individual, though at a little further
+date, Humanity itself may die!</p>
+
+<p>Before we leave this dead world, let us take a last glance at
+one of its fairest scenes,—that which we obtain when looking at
+a portion on which the sun is rising, as in this view of Gassendi
+(<a href="#ip_76">Fig. 76</a>), in which the dark part on our right is still the body of
+the moon, on which the sun has not yet risen. Its nearly level
+rays stretch elsewhere over a surface that is, in places, of a
+strangely smooth texture, contrasting with the ruggedness of
+the ordinary soil, which is here gathered into low plaits, that,
+with the texture we have spoken of, look</p>
+
+<div class="poetry-container">
+<div class="poetry">
+  <div class="stanza">
+    <div class="verse indentq">“Like marrowy crapes of China silk,</div>
+    <div class="verse indent0">Or wrinkled skin on scalded milk,”</div>
+  </div>
+</div>
+</div>
+
+<p class="in0">as they lie, soft and almost beautiful, in the growing light.</p>
+
+<p>Where its first beams are kindling, the summits cast their
+shadows illimitedly over the darkening plains away on the right,
+until they melt away into the night,—a night which is not
+utterly black, for even here a subdued radiance comes from the
+earth-shine of our own world in the sky.</p>
+
+<p>Let us leave here the desolation about us, happy that we can
+come back at will to that world, our own familiar dwelling,
+where the meadows are still green and the birds still sing, and
+where, better yet, still dwells our own kind,—surely the world,
+of all we have found in our wanderings, which we should ourselves
+have chosen to be our home.</p>
+
+<p><span class="pagenum" id="Page_173">173</span></p>
+
+<div id="ip_76" class="figcenter" style="max-width: 29em;">
+  <img src="images/i_173.jpg" alt="" />
+  <div class="caption">FIG. 76.—GASSENDI. NOV. 7, 1867.</div></div>
+
+<hr />
+
+<div id="toclink_175" class="chapter">
+<p><span class="pagenum" id="Page_175">175</span></p>
+
+<h2 class="nobreak" id="VI">VI.<br />
+
+<span class="subhead">METEORS.</span></h2>
+</div>
+
+<p class="drop-cap"><span class="smcap1">What</span> is truth? What is fact, and what is fancy, even
+with regard to solid visible things that we may see and
+handle?</p>
+
+<p>Among the many superstitions of the early world and credulous
+fancies of the Middle Ages, was the belief that great stones
+sometimes fell down out of heaven onto the earth.</p>
+
+<p>Pliny has a story of such a black stone, big enough to load
+a chariot; the Mussulman still adores one at Mecca; and a mediæval
+emperor of Germany had a sword which was said to
+have been forced from one of these bolts shot out of the blue.
+But with the revival of learning, people came to know better!
+That stones should fall down from the sky was clearly, they
+thought, an absurdity; indeed, according to the learned opinion
+of that time, one would hardly ask a better instance of the difference
+between the realities which science recognized and the
+absurdities which it condemned than the fancy that such a thing
+could be. So at least the matter looked to the philosophers of
+the last century, who treated it much as they might treat certain
+alleged mental phenomena, for instance, if they were alive to-day,
+and at first refused to take any notice of these stories, when
+from time to time they still came to hand. When induced to
+give the matter consideration, they observed that all the conditions
+for scientific observation were violated by these bodies,
+since the wonder always happened at some far-off place or at<span class="pagenum" id="Page_176">176</span>
+some past time, and (suspicious circumstance!) the stones only
+fell in the presence of ignorant and unscientific witnesses, and
+never when scientific men were at hand to examine the facts.
+That there were many worthy, if ignorant, men who asserted
+that they had seen such stones fall, seen them with their very
+eyes, and held them in their own hands, was accounted for by
+the general love of the marvellous and by the ignorance of the
+common mind, unlearned in the conditions of scientific observation,
+and unguided by the great principle of the uniformity of
+the Laws of Nature.</p>
+
+<p>Such a tone, of course, cannot be heard among us, who never
+hastily pronounce anything a departure from the “Laws of
+Nature,” while uncertain that these can be separated from the
+laws of the fallible human mind, in which alone Nature is seen.
+But in the last century philosophers had not yet become humble,
+or scientific men diffident of the absoluteness of their own knowledge,
+and so it seemed that no amount of evidence was enough
+to gain an impartial hearing in the face of the settled belief that
+the atmosphere extended only a few miles above the earth’s surface,
+and that the region beyond, whence alone such things
+could come, was an absolute void extending to the nearest
+planet.</p>
+
+<div id="ip_77" class="figcenter" style="max-width: 27em;">
+  <img src="images/i_177.jpg" alt="" />
+  <div class="caption"><p>FIG. 77.—THE CAMP AT MOUNT WHITNEY.</p>
+
+<p>(FROM “PROFESSIONAL PAPERS OF THE SIGNAL SERVICE,” VOL. XV.)</p></div></div>
+
+<p>It used to be supposed that we were absolutely isolated, not
+only from the stars but from other planets, by vast empty spaces
+extending from world to world,—regions altogether vacant except
+for some vagrant comet; but of late years we are growing
+to have new ideas on this subject, and not only to consider space
+as far from void or tenantless, but to admit, as a possibility at
+least, that there is a sort of continuity between our very earth’s
+surface, the air above it, and all which lies beyond the blue
+overarching dome of our own sky. Our knowledge of the
+physical nature of the universe without has chiefly come from
+what the spectroscope, overleaping the space between us and<span class="pagenum" id="Page_179">179</span>
+the stars, has taught us of them; as a telegram might report to
+us the existence of a race across the ocean, without telling anything
+of what lay between. It would be a novel path to the
+stars, and to the intermediate regions whence these once mythical
+stones are now actually believed to come, if we could take
+the reader to them by a route which enabled us to note each
+step of a continuous journey from the earth’s surface out into
+the unknown; but if we undertake to start upon it, he will understand
+that we must almost at the outset leave the ground of
+comparative certainty on which we have hitherto rested, and
+need to speak of things on this road which are still but probabilities,
+and even some which are little more than conjectures,
+before we get to the region of comparative certainty again,—a
+region which, strange to say, exists far away from us, while that
+of doubt lies close at hand, for we may be said without exaggeration
+to know more about Sirius than about the atmosphere
+a thousand miles above the earth’s surface; indeed, it would be
+more just to say that we are sure not only of the existence but
+of the elements that compose a star, though a million of times
+as far off as the sun, while at the near point named we are not
+sure of so much as that the atmosphere exists at all.</p>
+
+<p>To begin our outward journey in a literal sense, we might
+rise from the earth’s surface some miles in a balloon, when we
+should find our progress stayed by the rarity of the air. Below
+us would be a gray cloud-ocean, through which we could see
+here and there the green earth beneath, while above us there
+would still be something in the apparently empty air, for if
+the sun has just set it will still be <em>light</em> all round us. Something
+then, in a cloudless sky, still exists to reflect the rays towards
+us, and this something is made up of separately invisible specks
+of dust and vapor, but very largely of actual dust, which probably
+forms the nucleus of each mist-particle. That discrete
+matter of some kind exists here has long been recognized from<span class="pagenum" id="Page_180">180</span>
+the phenomena of twilight; but it is, I think, only recently that
+we are coming to admit that a shell of actual solid particles in
+the form of dust probably encloses the whole globe, up to far
+above the highest clouds.</p>
+
+<p>In 1881 the writer had occasion to conduct a scientific expedition
+to the highest point in the territories of the United States,
+on one of the summits of the Sierra Nevadas of Southern California,
+which rise even above the Rocky Mountains.</p>
+
+<p>The illustration on page 177 represents the camp occupied by
+this party below the summit, where the tents, which look as if in
+the bottom of a valley, are yet really above the highest zone of
+vegetation, and at an altitude of nearly twelve thousand feet.</p>
+
+<p>Still above these rise the precipices of barren rock seen in the
+background, their very bases far above the highest visible dust-clouds,
+which overspread like a sea the deserts at the mountain’s
+foot,—precipices which when scaled lift the observer into what
+is, perhaps, the clearest and purest air to be found in the world.
+It will be seen from the mere looks of the landscape that we are
+far away here from ordinary sources of contamination in the
+atmosphere. Yet even above here on the highest peak, where
+we felt as if standing on the roof of the continent and elevated
+into the great aerial currents of the globe, the telescope showed
+particles of dust in the air, which the geologists deemed to have
+probably formed part of the soil of China and to have been
+borne across the Pacific, but which also, as we shall see later,
+may owe something to the mysterious source of the phenomena
+already alluded to.</p>
+
+<p>It is far from being indifferent to us that the dust is there;
+for, to mention nothing else, without it, it would be night till
+the sunrise, and black night again as soon as the sun’s edge
+disappeared below the horizon. The morning and the evening
+twilight, which in northern latitudes increase our average time
+of light by some hours, and add very materially to the actual<span class="pagenum" id="Page_181">181</span>
+days of man’s life, are probably due almost wholly to particles
+scarcely visible in the microscope, and to the presence of such
+atoms, smaller than the very motes ordinarily seen in the sunbeam,
+which, as Mr. Aitken has shown, fill the air we breathe,—so
+minute and remote are the causes on which the habits of life
+depend.</p>
+
+<p>Before we can see that a part of this impalpable, invisible
+dust is also perhaps a link between our world and other members
+of the solar system, we must ask how it gets into the atmosphere.
+Is it blown up from the earth, or does it fall down out
+of the miscalled “void” of space?</p>
+
+<p>If we cast a handful of dust into the air, it will not mount
+far above the hand unless we set the air in motion with it, as in
+ascending smoke-currents; and the greatest explosions we can
+artificially produce, hurl their finer products but a few hundred
+feet at most from the soil. Utterly different are the forces of
+Nature. We have on page 183 a reproduction from a photograph
+of an eruption of Vesuvius,—a mere toy-volcano compared
+to Etna or Hecla. But observe the smoke-cloud which
+rises high in the sunshine, looking solid as the rounded snows
+of an Alp, while the cities and the sea below are in the shadow.
+The smoke that mounts from the foreground, where the burning
+lava-streams are pouring over the surface and firing the woods,
+is of another kind from that rolling high above. <em>This</em> comes
+from within the mountain, and is composed of clouds of steam
+mingled with myriads of dust-particles from the comminuted
+products of the earth’s interior; and we can see ourselves that it
+is borne away on a level, miles high in the upper air.</p>
+
+<p>But what is this to the eruption of Sumbawa or Krakatao?
+The latter occurred in 1883, and it will be remembered that the
+air-wave started by the explosion was felt around the globe, and
+that, probably owing to the dust and water-vapor blown into the
+atmosphere, the sunsets even in America became of that extraordinary<span class="pagenum" id="Page_182">182</span>
+crimson we all remember three years ago; and coincidently,
+that dim reddish halo made its appearance about the
+sun, the world over, which is hardly yet gone.<a id="FNanchor_6" href="#Footnote_6" class="fnanchor">6</a> Very careful
+estimates of the amount of ashes ejected have been made; and
+though most of the heavier particles are known to have fallen
+into the sea within a few miles, a certain portion—the lightest—was
+probably carried by the explosion far above the lower
+strata of the atmosphere, to descend so slowly that some of it
+may still be there. Of this lighter class the most careful estimates
+must be vague; but according to the report of the official
+investigation by the Dutch Government, that which remained
+floating is something enormous. An idea of its amount may
+be gained by supposing these impalpable and invisible particles
+to condense again from the upper sky, and to pour down on
+the highest edifice in the world, the Washington Monument. If
+the dust were allowed to spread out on all sides, till the pyramidal
+slope was so flat as to be permanent, the capstone of the
+monument would not only be buried before the supply was
+exhausted, but buried as far below the surface as that pinnacle
+is now above it.</p>
+
+<div class="footnote">
+
+<p><a id="Footnote_6" href="#FNanchor_6" class="fnanchor">6</a> In January, 1887.</p>
+
+</div>
+
+<p>Of the explosive suddenness with which the mass was hurled,
+we can judge something (comparing small things with great) by
+the explosion of dynamite.</p>
+
+<p>It happened once that the writer was standing by a car in
+which some railway porters were lifting boxes. At that moment
+came an almost indescribable sound, for it was literally stunning,
+though close and sharp as the crack of a whip in one’s
+hand, and yet louder than the nearest thunder-clap. The men
+leaped from the car, thinking that one of the boxes had exploded
+between them; but the boxes were intact, and we saw what
+seemed a pillar of dust rising above the roof of the station, hundreds
+of yards away. When we hurried through the building,<span class="pagenum" id="Page_185">185</span>
+we found nothing on the other side but a bare plain, extending
+over a mile, and beyond this the actual scene of the explosion
+that had seemed to be at our feet. There had been there, a few
+minutes before, extensive buildings and shops belonging to the
+railroad, and sidings on which cars were standing, two of which,
+loaded with dynamite, had exploded.</p>
+
+<div id="ip_78" class="figcenter" style="max-width: 29em;">
+  <img src="images/i_183.jpg" alt="" />
+  <div class="caption">FIG. 78.—VESUVIUS DURING AN ERUPTION.</div></div>
+
+<p>Where they <em>had</em> been was a crater-like depression in the
+earth, some rods in diameter; the nearest buildings, great solid
+structures of brick and stone, had vanished, and the more distant
+wooden ones and the remoter lines of freight-cars on the side-tracks
+presented a curious sight, for they were not shattered
+so much as bent and leaning every way, as though they had
+been built of pasteboard, like card-houses, and had half
+yielded to some gigantic puff of breath. All that the explosion
+had shot skyward had settled to earth or blown away
+before we got in sight of the scene, which was just as quiet
+as it had been a minute before. It was like one of the changes
+of a dream.</p>
+
+<p>Now, it is of some concern to us to know that the earth holds
+within itself similar forces, on an incomparably greater scale.
+For instance, the explosion which occurred at Krakatao, at five
+minutes past ten, on the 27th of August, 1883, according to official
+evidence, was heard at a distance of eighteen hundred miles,
+and the puff of its air-wave injured dwellings two hundred miles
+distant, and, we repeat, carried into the highest regions of the
+atmosphere and around the world matter which it is at least
+possible still affects the aspect of the sun to-day from New York
+or Chicago.</p>
+
+<p>Do not the great flames which we have seen shot out from
+the sun at the rate of hundreds of miles a second, the immense
+and sudden perturbations in the atmosphere of Jupiter, and the
+scarred surface of the moon, seem to be evidences of analogous
+phenomena, common to the whole solar system, not wholly<span class="pagenum" id="Page_186">186</span>
+unconnected with those of earthquakes, and which we can still
+study in the active volcanoes of the earth?</p>
+
+<p>If the explosion of gunpowder can hurl a cannon-shot three
+or four miles into the air, how far might the explosion of Krakatao
+cast its fragments? At first we might think there must
+be some proportionality between the volume of the explosion
+and the distance, but this is not necessarily so. Apart from the
+resistance of the air, it is a question of the velocity with which
+the thing is shot upward, rather than the size of the gun, or the
+size of the thing itself, and with a sufficient velocity the projectile
+would never fall back again. “What goes up must come
+down,” is, like most popular maxims, true only within the limits
+of ordinary experience; and even were there nothing else in the
+universe to attract it, and though the earth’s attraction extend to
+infinity, so that the body would never escape from it, it is yet
+quite certain that it would, with a certain initial velocity (very
+moderate in comparison with that of the planet itself), go up
+and <em>never</em> come back; while under other and possible conditions
+it might voyage out into space on a comet-like orbit, and be
+brought back to the earth, perhaps in after ages, when the original
+explosion had passed out of memory or tradition. But because
+all this is possible, it does not follow that it is necessarily
+true; and if the reader ask why he should then be invited to
+consider such suppositions at all, we repeat that in our journey
+outward, before we come to the stars, of which we know something,
+we pass through a region of which we know almost
+nothing; and this region, which is peopled by the subjects of
+conjecture, is the scene, if not the source, of the marvel of the
+falling stones, concerning which the last century was so incredulous,
+but for which we can, aided by what has just been said,
+now see at least a possible cause, and to which we now return.</p>
+
+<p>Stories of falling stones, then, kept arising from time to time
+during the last century as they had always done, and philosophers<span class="pagenum" id="Page_187">187</span>
+kept on disbelieving them as they had always done, till
+an event occurred which suddenly changed scientific opinion to
+compulsory belief.</p>
+
+<p>On the 26th of April, 1803, there fell, not in some far-off part
+of the world, but in France, not one alone, but many thousand
+stones, over an area of some miles, accompanied with noises like
+the discharge of artillery. A committee of scientific men visited
+the spot on the part of the French Institute, and brought back
+not only the testimony of scores of witnesses or auditors, but the
+stones themselves. Soon after stones fell in Connecticut, and
+here and elsewhere, as soon as men were prepared to believe,
+they found evidence multiplied; and such falls, it is now admitted,
+though rare in any single district, are of what may be
+called frequent occurrence as regards the world at large,—for,
+taking land and sea together, the annual stone-falls are probably
+to be counted by hundreds.</p>
+
+<p>It was early noticed that these stones consisted either of a
+peculiar alloy of iron, or of minerals of volcanic origin, or both;
+and the first hypothesis was that they had just been shot out
+from terrestrial volcanoes. As they were however found, as in
+the case of the Connecticut meteorite, thousands of miles from
+any active volcanoes, and were seen to fall, not vertically down,
+but as if shot horizontally overhead, this view was abandoned.
+Next the idea was suggested that they were coming from volcanoes
+in the moon; and though this had little to recommend it,
+it was adopted in default of a better, and entertained down to a
+comparatively very recent period. These stones are now collected
+in museums, where any one may see them, and are to
+be had of the dealers in such articles by any who wish to buy
+them. They are coming to have such a considerable money
+value that, in one case at least, a lawsuit has been instituted for
+their possession between the finder, who had picked the stones
+up on ground leased to him, and claimed them under the tenant’s<span class="pagenum" id="Page_188">188</span>
+right to wild game, and his landlord, who thought they were
+his as part of the real estate.</p>
+
+<p>Leaving the decision of this novel law-point to the lawyers,
+let us notice some facts now well established.</p>
+
+<p>The fall is usually preceded by a thundering sound, sometimes
+followed or accompanied by a peculiar noise described as
+like that of a flock of ducks rising from the water. The principal
+sound is often, however, far louder than any thunder, and
+sometimes of stunning violence. At night this is accompanied
+by a blaze of lightning-like suddenness and whiteness, and the
+stones commonly do not fall vertically, but as if shot from a
+cannon at long range. They are usually burning hot, but in
+at least one authenticated instance one was so intensely cold
+that it could not be handled. They are of all sizes, from tons
+to ounces, comparatively few, however, exceeding a hundred-weight,
+and they are oftenest of a rounded form, or looking like
+pieces of what was originally round, and usually wholly or
+partly covered with a glaze formed of the fused substance itself.
+If we slowly heat a lump of loaf sugar all through, it will form
+a pasty mass, while we may also hold it without inconvenience
+in our fingers to the gas-flame a few seconds, when it will be
+melted only on the side next the sudden heat, and rounded by
+the melting. The sharp contrast of the melted and the rough
+side is something like that of the meteorites; and just as the
+sugar does not burn the hand, though close to where it is
+brought suddenly to a melting heat, a mass of ironstone may
+be suddenly heated on the surface, while it remains cold on the
+inside. But, however it got there, the stone undoubtedly comes
+from the intensely cold spaces above the upper air; and what is
+the source of such a heat that it is melted in the cold air, and in
+a few seconds?</p>
+
+<div id="ip_79" class="figcenter" style="max-width: 25em;">
+  <img src="images/i_189.jpg" alt="" />
+  <div class="caption">FIG. 79.—METEORS OBSERVED NOV. 13 AND 14, 1868, BETWEEN MIDNIGHT
+AND FIVE O’CLOCK, A. M.</div></div>
+
+<p>Everybody has noticed that if we move a fan gently, the air
+parts before it with little effort, while, when we try to fan violently,<span class="pagenum" id="Page_191">191</span>
+the same air is felt to react; yet if we go on to say that
+if the motion is still more violent the atmosphere will resist like
+a solid, against which the fan, if made of iron, would break in
+pieces, this may seem to some an unexpected property of the
+“nimble” air through which we move daily. Yet this is the
+case; and if the motion is only so quick that the air cannot get
+out of the way, a body hurled against it will rise in temperature
+like a shot striking an armor-plate. It is all a question of speed,
+and that of the meteorite is known to be immense. One has
+been seen to fly over this country from the Mississippi to the
+Atlantic in an inappreciably short time, probably in less than
+two minutes; and though at a presumable height of over fifty
+miles, the velocity with which it shot by gave every one the impression
+that it went just above his head, and some witnesses of
+the unexpected apparition looked the next day to see if it had
+struck their chimneys. The heat developed by arrested motion
+in the case of a mass of iron moving twenty miles a second can
+be calculated, and is found to be much more than enough, not
+only to melt it, but to turn it into vapor; though what probably
+does happen is, according to Professor Newton, that the melted
+surface-portions are wiped away by the pressure of the air and
+volatilized to form the luminous train, the interior remaining
+cold, until the difference of temperature causes a fracture, when
+the stone breaks and pieces fall,—some of them at red-hot heat,
+some of them possibly at the temperature of outer space, or far
+below that of freezing mercury.</p>
+
+<p>Where do these stones come from? What made them? The
+answer is not yet complete; but if a part of the riddle is already
+yielding to patience, it is worthy of note, as an instance of the
+connection of the sciences, that the first help to the solution
+of this astronomical enigma came from the chemists and the
+geologists.</p>
+
+<p>The earliest step in the study, which has now been going on<span class="pagenum" id="Page_192">192</span>
+for many years, was to analyze the meteorite, and the first result
+was that it contained no elements not found on this planet. The
+next was that, though none of these elements were unknown,
+they were not combined as we see them in the minerals we dig
+from the earth. Next it was found that the combinations, if unfamiliar
+at the earth’s surface and nowhere reproduced exactly,
+were at least very like such as existed down beneath it, in lower
+strata, as far as we can judge by specimens of the earth’s interior
+cast up from volcanoes. Later, a resemblance was recognized
+in the elements of the meteorites to those found by the spectroscope
+in shooting stars, though the spectroscopic observation of
+the latter is too difficult to have even yet proceeded very far.
+And now, within the last few years, we seem to be coming near
+to a surprising solution.</p>
+
+<p>It has now been shown that meteoric stones sometimes contain
+pieces of essentially different rocks fused together, and
+pieces of detritus,—the wearing down of older rocks. Thus, as
+we know that sandstone is made of compacted sand, and sand
+itself was in some still earlier time part of rocks worn down by
+friction,—when it is shown, as it has been by M. Meunier, that
+a sandstone penetrated by metallic threads (like some of our terrestrial
+formations) has come to us in a meteorite, the conclusion
+that these stones may be part of some old world is one that,
+however startling, we cannot refuse at least to consider. According
+to this view, there may have been a considerable planet
+near the earth, which, having reached the last stage of planetary
+existence shown in the case of our present moon, went one step
+further,—went, that is, out of existence altogether, by literal
+breaking up and final disappearance. We have seen the actual
+moon scarred and torn in every direction, and are asked to
+admit the possibility that a continuance of the process on a
+similar body has broken it up into the fragments that come to
+us. We do not say that this is the case, but that (as regards<span class="pagenum" id="Page_193">193</span>
+the origin of some of the meteorites at least) we cannot at
+present disprove it. We may, at any rate, present to the novelist
+seeking a new <i xml:lang="fr" lang="fr">motif</i> that of a meteorite bringing to us the story
+of a lost race, in some fragment of art or architecture of its lost
+world!</p>
+
+<p>We are not driven to this world-shattering hypothesis by the
+absence of others, for we may admit these to be fragments of a
+larger body without necessarily concluding that it was a world
+like ours, or, even if it were, that the world which sent them to
+us is destroyed. In view of what we have been learning of the
+tremendous explosive forces we see in action on the sun and
+probably on other planets, and even in terrestrial volcanoes to-day,
+it is certainly conceivable that some of these stones may
+have been ejected by some such process from any sun, or star,
+or world we see. The reader is already prepared for the suggestion
+that part of them may be the product of terrestrial
+volcanoes in early epochs, when our planet was yet glowing
+sunlike with its proper heat, and the forces of Nature were
+more active; and that these errant children of mother earth’s
+youth, after circulating in lengthened orbits, are coming back to
+her in her age.</p>
+
+<p>Do not let us, however, forget that these are mostly speculations
+only, and perhaps the part of wisdom is not to speculate
+at all till we learn more facts; but are not the facts themselves
+as extraordinary as any invention of fancy?</p>
+
+<p>Although it is true that the existence of the connection between
+shooting stars and meteorites lacks some links in the
+chain of proof, we may very safely consider them together;
+and if we wish to know what the New Astronomy has done for
+us in this field, we should take up some treatise on astronomy
+of the last century. We turn in one to the subject of falling
+stars, and find that “this species of Star is only a light Exhalation,
+almost wholly sulphurous, which is inflamed in the free Air<span class="pagenum" id="Page_194">194</span>
+much after the same manner as Thunder in a Cloud by the
+blowing of the Winds.” That the present opinion is different,
+we shall shortly notice.</p>
+
+<p>All of us have seen shooting stars, and they are indeed something
+probably as old as this world, and have left their record
+in mythology as well as in history. According to Moslem tradition,
+the evil genii are accustomed to fly at night up to the
+confines of heaven in order to overhear the conversation of
+the angels, and the shooting stars are the fiery arrows hurled
+by the latter at their lurking foes, with so good an aim that
+we are told that for every falling star we may be sure that
+there is one spirit of evil the less in the world. The scientific
+view of them, however, if not so consolatory, is perhaps more
+instructive, and we shall here give most attention to the
+latter.</p>
+
+<p>To begin with, there have been observed in history certain
+times when shooting stars were unusually numerous. The night
+when King Ibrahim Ben Ahmed died, in October, 902, was
+noted by the Arabians as remarkable in this way; and it has
+frequently been observed since, that, though we can always see
+some of these meteors nightly, there are at intervals very special
+displays of them. The most notable modern one was on Nov.
+13, 1833, and this was visible over much of the North American
+continent, forming a spectacle of terrifying grandeur. An eyewitness
+in South Carolina <span class="locked">wrote:—</span></p>
+
+<div class="blockquot">
+
+<p>“I was suddenly awakened by the most distressing cries that ever
+fell on my ears. Shrieks of horror and cries for mercy I could hear
+from most of the negroes of the three plantations, amounting in all to
+about six hundred or eight hundred. While earnestly listening for the
+cause I heard a faint voice near the door, calling my name. I arose,
+and, taking my sword, stood at the door. At this moment I heard the
+same voice still beseeching me to rise, and saying, ‘O my God, the world
+is on fire!’ I then opened the door, and it is difficult to say which
+excited me the most—the awfulness of the scene, or the distressed cries<span class="pagenum" id="Page_195">195</span>
+of the negroes. Upwards of one hundred lay prostrate on the ground,—some
+speechless and some with the bitterest cries, but with their hands
+raised, imploring God to save the world and them. ‘The scene was truly
+awful; for never did rain fall much thicker than the meteors fell toward
+the earth; east, west, north, and south, it was the same.”</p>
+</div>
+
+<p>The illustration on page 189 does not exaggerate the number
+of the fiery flashes at such a time, though the zigzag course
+which is observed in some is hardly so common as it here
+appears.</p>
+
+<p>When it was noted that the same date, November 13th, had
+been distinguished by star-showers in 1831 and 1832, and that
+the great shower observed by Humboldt in 1799 was on this
+day, the phenomenon was traced back and found to present
+itself about every thirty-three years, the tendency being to a
+little delay on each return; so that Professor Newton and others
+have found it possible with this clew to discover in early Arabic
+and other mediæval chronicles, and in later writers, descriptions
+which, fitted together, make a tolerably continuous record of this
+thirty-three-year shower, beginning with that of King Ibrahim
+already alluded to. The shower appeared again in November,
+1867 and 1868, with less display, but with sufficient brilliance
+to make the writer well remember the watch through the night,
+and the count of the flying stars, his most lively recollection
+being of their occasional colors, which in exceptional cases
+ranged from full crimson to a vivid green. The count on this
+night was very great, but the number which enter the earth’s atmosphere
+even ordinarily is most surprising; for, though any
+single observer may note only a few in his own horizon, yet,
+taking the world over, at least ten millions appear every night,
+and on these special occasions very many more. This November
+shower comes always from a particular quarter of the sky,
+that occupied by the constellation Leo, but there are others,
+such as that of August 10th (which is annual), in which the<span class="pagenum" id="Page_196">196</span>
+“stars” seem to be shot at us from the constellation Perseus;
+and each of the numerous groups of star-showers is now known
+by the name of the constellation whence it seems to come, so
+that we have <i>Perseids</i> on August 10th, <i>Geminids</i> on December
+12th, <i>Lyrids</i>, April 20th, and so on.</p>
+
+<p>The great November shower, which is coming once more in
+this century, and which every reader may hope to see toward
+1899, is of particular interest to us as the first whose movements
+were subjected to analysis; for it has been shown by the labors
+of Professor Newton, of Yale, and Adams, of Cambridge, that
+these shooting stars are bodies moving around the sun in an
+orbit which is completed in about thirty-three years. It is
+quite certain, too, that they are not exhalations from the earth’s
+atmosphere, but little solids, invisible till they shine out by the
+light produced by their own fusion. Each, then, moves on its
+own track, but the general direction of all the tracks concurs;
+and though some of them may conceivably be solidified gases,
+we should think of them not as gaseous in form, but as solid
+shot, of the average size of something like a cherry, or perhaps
+even of a cherry-stone, yet each an independent planetoid, flying
+with a hundred times the speed of a rifle-bullet on its separate
+way as far out as the orbit of Uranus; coming back three times
+in a century to about the earth’s distance from the sun, and
+repeating this march forever, unless it happen to strike the atmosphere
+of the earth itself, when there comes a sudden flash of
+fire from the contact, and the distinct existence of the little body,
+which may have lasted for hundreds of thousands of years, is
+ended in a second.</p>
+
+<p>If the reader will admit so rough a simile, we may compare
+such a flight of these bodies to a thin swarm of swift-flying birds—thin,
+but yet immensely long, so as to be, in spite of the rapid
+motion, several years in passing a given point, and whose line of
+flight is cut across by us on the 13th of November, when the<span class="pagenum" id="Page_197">197</span>
+earth passes through it. We are only there on that day, and
+can only see it then; but the swarm is years in all getting by,
+and so we may pass into successive portions of it on the anniversary
+of the same day for years to come. The stars appear to
+shoot from Leo, only because that constellation is in the line of
+their flight when we look up to it, just as an interminable train
+of parallel flying birds would appear to come from some definite
+point on the horizon.</p>
+
+<p>We can often see the flashes of meteors at over a hundred
+miles, and though at times they may seem to come thick as
+Hakes of falling snow, it is probable, according to Professor
+Newton, that even in a “shower” each tiny planetoid is more
+than ten miles from its nearest neighbor, while on the average it
+is reckoned that we may consider that each little body, though
+possibly no larger than a pea, is over two hundred miles from
+its neighbor, or that to each such grain there is nearly ten
+million cubic miles of void space. Their velocity as compounded
+with that of the earth is enormous, sometimes forty
+to fifty miles per second (according to a recent but unproved
+theory of Mr. Denning, it would be much greater), and it is
+this enormous rate of progress that affords the semblance of an
+abundant fall of rain, notwithstanding the distance at which one
+drop follows another. It is only from their light that we are
+able to form a rough estimate of their average size, which is, as
+we have seen, extremely small; but, from their great number,
+the total weight they add to the earth daily may possibly be a
+hundred tons, probably not very much more. As they are as
+a rule entirely dissipated in the upper air, often at a height of
+from fifty to seventy miles, it follows that many tons of the
+finest pulverized and gaseous matter are shot into the earth’s atmosphere
+every twenty-four hours from outer space, so that here
+is an independent and constant supply of dust, which we may
+expect to find coming down from far above the highest clouds.</p>
+
+<p><span class="pagenum" id="Page_198">198</span></p>
+
+<p>Now, when the reader sees the flash of a shooting star, he
+may, if he please, think of the way the imagination of the East
+accounts for it, or he may look at what science has given him
+instead. In the latter case he will know that a light which
+flashed and faded almost together came from some strange little
+entity which had been traversing cold and vacant space for untold
+years, to perish in a moment of more than fiery heat; an
+enigma whose whole secret is unknown, but of which, during
+that instant flash, the spectroscope caught a part, and found evidence
+of the identity of some of its constituents with those of the
+observer’s own body.</p>
+
+<hr />
+
+<div id="toclink_199" class="chapter">
+<p><span class="pagenum" id="Page_199">199</span></p>
+
+<h2 class="nobreak" id="VII">VII.<br />
+
+<span class="subhead">COMETS.</span></h2>
+</div>
+
+<p class="drop-cap"><span class="smcap1">Of</span> comets, the Old Astronomy knew that they came to the
+sun from great distances in all directions, and in calculable
+orbits; but as to <em>what</em> they were, this, even in the childhood of
+those of us who are middle-aged, was as little known as to the
+centuries during which they still from their horrid heads shook
+pestilence and war. We do not know even now by any means
+exactly what they are, for enough yet remains to be learned
+about them still to give their whole study the attraction which
+belongs to the unknown; and yet we learn so much, and in a
+way which to our grandfathers would have been so unexpected,
+connecting together the comet, the shooting star, and the meteorite,
+that the astronomer who perhaps speaks with most authority
+about these to-day was able, not long ago, in beginning a
+lecture, to state that he held in his hand what had been a part
+of a comet; and what he held was, not something half vaporous
+or gaseous, as we might suppose from our old associations, but a
+curious stone like this on page 203, which, with others, had
+fallen from the sky in Iowa, a flashing prodigy, to the terror
+of barking dogs, shying horses, and fearful men, followed by
+clouds of smoke and vapor, and explosions that shook the houses
+like an earthquake, and “hollow bellowings and rattling sounds
+mingled with clang and clash and roar,” as an auditor described
+it. It is only a fragment of a larger stone which may have
+weighed tons. It looks inoffensive enough now, and its appearance<span class="pagenum" id="Page_200">200</span>
+affords no hint of the commotion it caused in a peaceable
+neighborhood only ten years ago. But what, it may be asked,
+is the connection between such things and comets?</p>
+
+<p>To answer this, let us recall the statement that the orbit of
+the November meteor swarm has been computed; which means
+that those flying bodies have been found to come only from one
+particular quarter out of all possible quarters, at one particular
+angle out of all possible angles, at one particular velocity out of
+all possible velocities, and so on; so that the chances are endless
+against mere accident producing another body which agreed in
+all these particulars, and others besides. Now, in 1867 the remarkable
+fact was established that a comet seen in the previous
+year (Comet 1, 1866) had the same orbit as the meteoroids,
+which implies, as we have just seen, that the comet and the
+meteors were in some way closely related.</p>
+
+<p>The paths of the August meteors and of the Lyrids also have
+both been found to agree closely with those of known comets,
+and there is other evidence which not only connects the comets
+and the shooting stars, and makes it probable that the latter are
+due to some disintegration of the former, but even looks as
+though the process were still going on. And now with this in
+mind we may, perhaps, look at these drawings with more
+interest.</p>
+
+<div id="ip_80" class="figcenter" style="max-width: 34em;">
+  <img src="images/i_201.jpg" alt="" />
+  <div class="caption">FIG. 80.—COMET OF DONATI, SEPT. 16, 1858.<a id="FNanchor_7" href="#Footnote_7" class="fnanchor">7</a></div></div>
+
+<div class="footnote">
+
+<p><a id="Footnote_7" href="#FNanchor_7" class="fnanchor">7</a> The five engravings of the Comet of Donati are from “Annals of the Astronomical Observatory of Harvard College.”</p>
+
+</div>
+
+<p>We have all seen a comet, and we have all felt, perhaps,
+something of the awe which is called up by the thought of its
+immensity and its rush through space like a runaway star. Its
+head is commonly like a small luminous point, from which
+usually grows as it approaches the sun a relatively enormous
+brush or tail of pale light, which has sometimes been seen to
+stretch across the whole sky from zenith to horizon. It is useless
+to look only along the ecliptic road for a comet’s coming;
+rather may we expect to see it rushing down from above, or up
+from below, sometimes with a speed which is possibly greater<span class="pagenum" id="Page_203">203</span>
+than it could get from any fall—not so much, that is, the speed
+of a body merely dropping toward the sun by its weight, as
+that of a missile hurled into the orderly solar system from some
+unknown source without, and also associated with some unknown
+power; for while it is doubtful whether gravity is sufficient
+to account for the velocity of all comets, it seems certain
+that gravity can in no way explain
+some of the phenomena of
+their tails.</p>
+
+<div id="ip_81" class="figright" style="max-width: 14em;">
+  <img src="images/i_203.jpg" alt="" />
+  <div class="caption">FIG. 81.—“A PART OF A COMET.”</div></div>
+
+<p>Thousands of comets have
+been seen since the Christian
+era, and the orbits of hundreds
+have been calculated since the
+time of Newton. Though they
+may describe any conic section,
+and though most orbits are
+spoken of as parabolas, this is
+rather a device for the analyst’s
+convenience than the exact representation
+of fact. Without
+introducing more technical language,
+it will be enough to say
+here that we learn in other cases
+from the form of the orbit whether the body is drawn essentially
+by the sun’s gravity, or whether it has been thrown
+into the system by some power beyond the sun’s control, to
+pass away again, out of that control, never to return. It
+must be admitted, however, that though several orbits are so
+classed, there is not any one known to be beyond doubt of
+this latter kind, while we are certain that many comets, if not
+all, are erratic members of the solar family, coming back
+again after their excursions, at regular, though perhaps enormous,
+intervals.</p>
+
+<p><span class="pagenum" id="Page_204">204</span></p>
+
+<p>But what we have just been saying belongs rather to the
+province of the Old Astronomy than the New, which concerns
+itself more with the nature and appearance of the heavenly
+bodies than the paths they travel on. Perhaps the best way for
+us to look at comets will be to confine our attention at first to
+some single one, and to follow it from its earliest appearance
+to its last, by the aid of pictures, and thus to study, as it were,
+the species in the individual. The difficulty will be one which
+arises from the exquisitely faint and diaphanous appearance of
+the original, which no ordinary care can possibly render, though
+here the reader has had done for him all that the wood-engraver
+can do.</p>
+
+<p>We will take as the subject of our illustration the beautiful
+comet which those of us who are middle-aged can remember
+seeing in 1858, and which is called Donati’s from the name of its
+discoverer. We choose this one because it is the subject of an
+admirable monograph by Professor Bond of the Harvard College
+Observatory, from which our engravings have, by permission,
+been made.</p>
+
+<p>Let us take the history of this comet, then, as a general type
+of others; and to begin at the beginning, we must make the
+very essential admission that the origin of the comet’s life is unknown
+to us. Where it was born, or how it was launched on its
+eccentric path, we can only guess, but do not know; and how
+long it has been traversing it we can only tell later. On the
+2d of June, 1858, this one was discovered in the way most comets
+are found, that is, by a <em>comet-hunter</em>, who detected it as a
+telescopic speck long before it became visible to the naked eye,
+or put forth the tail which was destined to grow into the beautiful
+object many of us can remember seeing. For over a century
+now there has been probably no year in which the heavens
+have not been thus searched by a class of observers who make
+comet-hunting a specialty.</p>
+
+<p><span class="pagenum" id="Page_205">205</span></p>
+
+<div id="ip_82" class="figcenter" style="max-width: 33em;">
+  <img src="images/i_205.jpg" alt="" />
+  <div class="caption">FIG. 82.—COMET OF DONATI, SEPT. 24, 1858. (TELESCOPIC VIEW OF HEAD.)</div></div>
+
+<p><span class="pagenum" id="Page_207">207</span></p>
+
+<p>The father of this very valuable class of observers appears to
+have been Messier, a Frenchman of the last century and of the
+purest type of the comet-hunters, endowed by Nature with the
+instinct for their search that a terrier has for rats. In that
+grave book, Delambre’s “History of Astronomy,” as we plod
+along its dry statements and through its long equations, we
+find, unexpected as a joke in a table of logarithms, the following
+piece of human nature (quoted from Messier’s contemporary,
+La <span class="locked">Harpe):—</span></p>
+
+<div class="blockquot">
+
+<p>“He [Messier] has passed his life in nosing out the tracks of comets.
+He is a very worthy man, with the simplicity of a baby. Some years ago
+he lost his wife, and his attention to her prevented him from discovering
+a comet he was on the search for, and which Montaigne of Limoges got
+away from him. He was in despair. When he was condoled with on
+the loss he had met, he replied, with his head full of the comet, ‘Oh,
+dear! to think that when I had discovered twelve, this Montaigne
+should have got my thirteenth.’ And his eyes filled with tears, till,
+remembering what it was he ought to be weeping for, he moaned, ‘Oh,
+my poor wife!’ but went on crying for his comet.”</p>
+</div>
+
+<p>Messier’s scientific posterity has greatly multiplied, and it is
+rare now for a comet to be seen by the naked eye before it has
+been caught by the telescope of one of these assiduous searchers.
+Donati had, as we see, observed his some months before it became
+generally visible, and accordingly the engraving on page
+201 shows it as it appeared on the evening of September 16,
+1858, when the tail was already formed, and, though small, was
+distinct to the naked eye, near the stars of the Great Bear. The
+reader will easily recognize in the plate the familiar “dipper,” as
+the American child calls it, where the leading stars are put down
+with care, so that he may, if he please, identify them by comparison
+with the originals in the sky, even to the little companion
+to Mizar (the second in the handle of the “dipper,” and which
+the Arabs say is the lost Pleiad). We would suggest that he<span class="pagenum" id="Page_208">208</span>
+should note both the length of the tail on this evening as compared
+with the space between any two stars of the “dipper”
+(for instance, the two right-hand ones, called the “pointers”)
+and its distance from them, and then turn to page 209, where
+we have the same comet as seen a little over a fortnight later,
+on October 3d. Look first at its new place among the stars.
+The “dipper” is still in view, but the comet has drifted away
+from it toward the left and into other constellations. The large
+star close to the left margin of the plate, with three little stars
+below and to the right, is Arcturus; and the western stars of
+the Northern Crown are just seen higher up. Fortunately the
+“pointers,” with which we compared the comet on September
+16th, are still here, and we can see for ourselves how it has not
+only shifted but grown. The tail is three times as long as
+before. It is rimmed with light on its upper edge, and fades
+away so gradually below that one can hardly say where it ends.
+But,—wonderful and incomprehensible feature!—shot out from
+the head, almost as straight as a ray of light itself, but fainter
+than the moonbeam, now appears an extraordinary addition, a
+sort of spur, which we can hardly call a new tail, it is so unlike
+the old one, but which appears to have been darted out into
+space as if by some mysterious force acting through the head
+itself. What the spur is, what the tail is, even what the nucleus
+is, we cannot be said really to know even to-day; but of the tail
+and of the nucleus or speck in the very head of the comet (too
+small to be visible in the engraving), we may say that the hairy
+tail (<em>comes</em>) gives the comet its name, and <em>is</em> the comet to popular
+apprehension, but that it is probably the smallest part of the
+whole mass, while the little shining head, which to the telescope
+presents a still smaller speck called the nucleus, contains, it now
+seems probable, the only element of possible danger to the earth.</p>
+
+<p>While admitting our lack of absolute knowledge, we may, if
+we agree that meteorites were once part of a comet, say that it<span class="pagenum" id="Page_211">211</span>
+now seems probable that the nucleus is a hard, stone-like mass,
+or collection of such masses, which comes from “space” (that
+is, from we don’t know how far) to the vicinity of the sun, and
+there is broken by the heat as a stone in a hot fire. (Sir Isaac
+Newton calculates, in an often quoted passage of the Principia,
+that the heat which the comet of 1680 was subjected to in its
+passage by the sun was two thousand times that of red-hot
+iron.) We have seen the way in which meteoric stones actually
+do crack in pieces with heat in our own atmosphere, partly,
+perhaps, from the expansion of the gases the stone contains, and
+it seems entirely reasonable to suppose that they may do so
+from the heat of the sun, and that the escaped gases may contribute
+something toward the formation of the tail, which is
+always turned away from the sun, and which always grows
+larger as that is approached, and smaller as it is receded from.
+However this may be, there is no doubt that the original solid
+which we here suppose may form the nucleus is capable of mischief,
+for it is asserted that it often passes the earth’s orbit with
+a velocity of as much as one hundred times that of a cannon-ball;
+that is, with ten thousand times the destructive capacity of
+a ball of the same weight shot from a cannon.</p>
+
+<div id="ip_83" class="figcenter" style="max-width: 36em;">
+  <img src="images/i_209.jpg" alt="" />
+  <div class="caption">FIG. 83.—COMET OF DONATI, OCT. 3, 1858.</div></div>
+
+<p>One week later, October 9th, the comet had passed over Arcturus
+with a motion toward our left into a new region of the
+sky, leaving Arcturus, which we can recognize with the upper
+one of its three little companions, on the right. Above it is the
+whole sickle of the Northern Crown, and over these stars the extremity
+of the now lengthened tail was seen to spread, but with
+so thin a veil that no art of the engraver can here adequately
+represent its faintness. The tail then, as seen in the sky, was
+now nearly twice its former size, though for the reason mentioned
+it may not appear so in our picture. It should be understood,
+too, that even the brightest parts of the original were far
+fainter than they seem here in comparison with the stars, which<span class="pagenum" id="Page_212">212</span>
+in the sky are brilliant points of light, which the engraver can
+only represent by dots of the whiteness of the paper. This
+being observed, it will be better understood that in the sky itself
+the faintest stars were viewed apparently undimmed through the
+brighter parts of the comet, while we can but faintly trace here
+another most faint but curious feature, a division of the tail into
+faint cross-bands like auroral streamers, giving a look as if it
+were yielding to a wind, which folded it into faint ridges like
+those which may be seen in the smoke of a steamer as it lags far
+behind the vessel. In fact, when we speak of “the” tail, it must
+be understood, as M. Faye reminds us, to be in the same sense
+that we speak of the plume of smoke that accompanies an ocean
+steamer, without meaning that it is the same thing which we are
+watching from night to night, more than we do that the same
+smoke-particles accompany the steamer as it moves across
+the Atlantic. In both cases the form alone probably remains;
+the thing itself is being incessantly dissipated and renewed.
+There is no air here, and yet some of these appearances in the
+original almost suggest the idea of medium inappreciably thin
+as compared with the head of the comet, but whose resistance is
+seen in the more unsubstantial tail, as that is drawn through it
+and bent backward, as if by a wind blowing toward the celestial
+pole.</p>
+
+<p>The most notable feature, however, is the development of a
+second ray or spur, which has been apparently darted through
+millions of miles in the interval since we looked at it, and an
+almost imperceptible bending backward in both, as if they too
+felt the resistance of something in what we are accustomed to
+think of as an absolute and perfect void. These tails are a
+peculiarly mysterious feature. They are apparently shot out
+in a direction opposite to the sun (and consequently opposed
+to the direction of gravity) at the rate of millions of miles a
+day.</p>
+
+<p><span class="pagenum" id="Page_213">213</span></p>
+
+<div id="ip_84" class="figcenter" style="max-width: 45em;">
+  <img src="images/i_213.jpg" alt="" />
+  <div class="caption">FIG. 84.—COMET OF DONATI, OCT. 9, 1858.</div></div>
+
+<p><span class="pagenum" id="Page_215">215</span></p>
+
+<p>Beyond the fact that the existence of some <em>repulsive</em> force in
+the sun, a “negative gravity” actually existent, not in fancy,
+but in fact, seems pointed at, astronomers can offer little but
+conjecture here; and while some conceive this force as of an
+electrical nature, others strenuously deny it. We ought to admit
+that up to the present time we really know nothing about it,
+except that it exists.</p>
+
+<p>At this date (October 9th) the comet had made nearly its
+closest approach to the earth, and the general outline has been
+compared to that of the wing of some bird, while the actual size was
+so vast that even at the distance from which it was seen it filled
+an angle more than half of that from the zenith to the horizon.</p>
+
+<p>All the preceding drawings have been from naked-eye views;
+but if the reader would like to look more closely, he can see on
+page 217 one taken on the night of October 5th through the
+great telescope at Cambridge, Mass. We will leave this to tell
+its own story, only remarking that it is not possible to reproduce
+the phantom-like faintness of the original spur, here also distinctly
+seen, or indeed to indicate fairly the infinite tenuity of
+the tail itself. Though millions of miles thick, the faintest star
+is yet perceptibly undimmed by it, and in estimating the character
+and quantity of matter it contains, after noting that it is
+not self-luminous, but shines only like the moon by reflected
+sunlight, we may recall the acute observation of Sir Isaac
+Newton where he compares the brightness of a comet’s tail with
+that of the light reflected from the particles in a sunbeam an
+inch or two thick, in a darkened room, and, after observing that
+if a little sphere of common air one inch in diameter were rarified
+to the degree which must obtain at only four thousand miles
+from the earth’s surface it would fill all the regions of the planets
+to far beyond the orbit of Saturn, suggests the excessively small
+quantity of vapor that is really requisite to create this prodigious
+phantom.</p>
+
+<p><span class="pagenum" id="Page_216">216</span></p>
+
+<p>The writer has had occasion for many years to make a special
+study of the reflection of light from the sky; and if such studies
+may authorize him to express any opinion of his own, he would
+give his adhesion to the remark of Sir John Herschel, that the
+actual weight of matter in such a cometary tail may be conceivably
+only an affair of pounds or even ounces. But if this
+is true of the tail, it does not follow of the nucleus, just seen in
+this picture, but of which the engraving on page 205 gives a
+much more magnified view. It is a sketch of the head alone,
+taken from a telescopic view on the 24th of September. Here
+the direction of the comet is still toward the sun (which must be
+supposed to be some indefinite distance beyond the upper part
+of the drawing), and we see that the lucid matter appears to be
+first jetted up, and then forced backward on either side, as if by
+a wind <em>from</em> the sun, to form the tail, presenting successive
+crescent-shaped envelopes of decreasing brightness, which are
+not symmetrical, but one-sided, while sometimes the appearance
+is that of spurts of luminous smoke, wavering as if thrown out
+of particular parts of the internal nucleus “like a squib not held
+fast.” Down the centre of the tail runs a wonderfully straight
+black line, like a shadow cast from the nucleus. Only the
+nucleus itself still evades us, and even in this, the most magnified
+view which the most powerful telescope till lately in existence
+could give, remains a point.</p>
+
+<p>Considering the distance of the comet and the other optical
+conditions, this is still perfectly consistent with the possibility
+that it may have an actual diameter of a hundred miles or more.
+It “may” have, observe, not it “has,” for in fact we know nothing
+about it; but that it is at any rate less than some few
+hundred miles in diameter, and it may, for anything we can
+positively say, not be more than a very large stone, in which
+case our atmosphere would probably act as an efficient buffer if
+it struck us; or it may have a mass which, coupled with its terrible<span class="pagenum" id="Page_219">219</span>
+speed, would cause the shock of its contact not so much to
+pulverize the region it struck, as dissipate it and everything on
+it instantly into vapor.</p>
+
+<div id="ip_85" class="figcenter" style="max-width: 42em;">
+  <img src="images/i_217.jpg" alt="" />
+  <div class="caption">FIG. 85.—COMET OF DONATI, OCT. 5, 1858. (TELESCOPIC VIEW.)</div></div>
+
+<p>Of the remarkable investigations of the spectroscope on
+comets, we have only room left to say that they inform us
+that the most prominent cometary element seems to be carbon,—carbon,
+which Newton two hundred years before the spectroscope,
+and before the term “carbonic-acid gas” was coined,
+by some guess or divination had described in other words as
+possibly brought to us by comets to keep up the carbonic-acid-gas
+supply in our air,—carbon, which we find in our own
+bodies, and of which, according to this view, the comets are
+original sources.</p>
+
+<p>That <em>we</em> may be partly made of old and used-up comets,—surely
+it might seem that a madder fancy never came from the
+brain of a lunatic at the full of the moon!</p>
+
+<p>Science may easily be pardoned for not giving instant reception
+to such an idea, but let us also remember, first, that it is a
+consequence of that of Sir Isaac Newton, and that in the case
+of such a man as he we should not be hasty to think we understand
+his ignorance, when we may be “ignorant of his
+understanding;” and, second, that it has been rendered at least
+debatable by Dr. Hunt’s recent researches whether it is possible
+to account for the perennial supply of carbon from the earth’s
+atmosphere, without looking to some means of renewal external
+to the planet.</p>
+
+<p>The old dread of comets is passing away, and all that science
+has to tell us of them indicates that, though still fruitful sources
+of curiosity and indeed of wonder, they need no longer be
+objects of terror. Though there be, as Kepler said, more
+comets in the sky than fish in the ocean, the encounter of
+the earth with a comet’s tail would be like the encounter with
+a shadow, and the chance of a collision with the nucleus is<span class="pagenum" id="Page_220">220</span>
+remote indeed. We may sleep undisturbed even if a new comet
+is announced every month, though it is true that here as elsewhere
+lie remote possibilities of evil.</p>
+
+<p>The consideration of the unfamiliar powers certainly latent
+in Nature, such as belong to a little tremor of the planet’s surface
+or such as was shown in that scene I have described, when
+the comparatively insignificant effect of the few tons of dynamite
+was to make solid buildings unrealities, which vanished away
+as quickly as magic-lantern pictures from a screen, may help us
+to understand that the words of the great poet are but the possible
+expression of a physical fact, and that “the cloud-capped
+towers, the gorgeous palaces, the solemn temples,”—and we
+with them,—may indeed conceivably some day vanish as the
+airy nothings at the touch of Prospero’s wand, and without
+the warning to us of a single instant that the security of our
+ordinary lives is about to be broken. We concede this, however,
+in the present case only as an abstract possibility; for the
+advance of astronomical knowledge is much more likely to show
+that the kernel of the comet is but of the bigness of some large
+meteorite, against which our air is an efficient shield, and the
+chance of evil is in any case most remote,—in any case only
+such as may come in any hour of our lives from any quarter,
+not alone from the earthquake or the comet, but from “the
+pestilence that walketh in darkness;” from the infinitely little
+below and within us, as well as from the infinite powers of
+the universe without.</p>
+
+<hr />
+
+<div id="toclink_221" class="chapter">
+<p><span class="pagenum" id="Page_221">221</span></p>
+
+<h2 class="nobreak" id="VIII">VIII.<br />
+
+<span class="subhead">THE STARS.</span></h2>
+</div>
+
+<p class="drop-cap"><span class="smcap1">In</span> the South Kensington Museum there is, as everybody
+knows, an immense collection of objects, appealing to all
+tastes and all classes, and we find there at the same time people
+belonging to the wealthy and cultivated part of society lingering
+over the Louis Seize cabinets or the old majolica, and
+the artisan and his wife studying the statements as to the relative
+economy of baking-powders, or admiring Tippoo Saib’s
+wooden tiger.</p>
+
+<p>There is one shelf, however, which seems to have some
+attraction common to all social grades, for its contents appear
+to be of equal interest to the peer and the costermonger. It is
+the representation of a <em>man</em> resolved into his chemical elements,
+or rather an exhibition of the materials of which the human
+body is composed. There is a definite amount of water, for
+instance, in our blood and tissues, and there on the shelf are
+just so many gallons of water in a large vessel. Another jar
+shows the exact quantity of carbon in us; smaller bottles contain
+our iron and our phosphorus in just proportion, while others
+exhibit still other constituents of the body, and the whole reposes
+on the shelf as if ready for the coming of a new Frankenstein
+to re-create the original man and make him walk about again
+as we do. The little vials that contain the different elements
+which we all bear about in small proportions are more numerous,
+and they suggest, not merely the complexity of our constitutions,<span class="pagenum" id="Page_222">222</span>
+but the identity of our elements with those we have
+found by the spectroscope, not alone in the sun, but even in
+the distant stars and nebulæ; for this wonderful instrument of
+the New Astronomy can find the traces of poison in a stomach
+or analyze a star, and its conclusions lead us to think that the
+ancients were nearly right when they called man a microcosm,
+or little universe. We have literally within our own bodies
+samples of the most important elements of which the great
+universe without is composed; and you and I are not only like
+each other, and brothers in humanity, but children of the sun
+and stars in a more literal sense, having bodies actually made
+in large part of the same things that make Sirius and Aldebaran.
+They and we are near relatives.</p>
+
+<div id="ip_86" class="figcenter" style="max-width: 30em;">
+  <img src="images/i_222.jpg" alt="" />
+  <div class="caption">FIG. 86.—TYPES OF STELLAR SPECTRA.</div></div>
+
+<p>But if near in kind, we are distant relatives in another way,
+for the sun, whose remoteness we have elsewhere tried to give
+an idea of, is comparatively close at hand; quite at hand, one
+may say, for if his distance, which we have found so enormous,
+be represented by that of a man standing so close beside us that<span class="pagenum" id="Page_223">223</span>
+our hand may rest on his shoulder, to obtain the proportionate
+distance of one of the <em>nearest</em> stars, like Sirius, for instance, we
+should need to send the man over a hundred miles away. It is
+probably impossible to give to any one an adequate idea of the
+extent of the sidereal universe; but it certainly is especially hard
+for the reader who has just realized with difficulty the actual
+immensity of the distance of the sun, and who is next told that
+this distance is literally a physical point as seen from the nearest
+star. The jaded imagination can be spurred to no higher flight,
+and the facts and the enormous numbers that convey them will
+not be comprehended.</p>
+
+<p>Look down at one of the nests of those smallest ants, which
+are made in our paths. To these little people, we may suppose,
+the other side of the gravel walk is the other side of the world,
+and the ant who has been as far as the gate, a greater traveller
+than a man who comes back from the Indies. It is very hard to
+think not only of ourselves as relatively far smaller than such
+insects, but that, less than such an ant-hill is to the whole landscape,
+is our solar system itself in comparison with the new
+prospect before us; yet so it is.</p>
+
+<p>All greatness and littleness are relative. When the traveller
+from the great star Sirius (where, according to the author of
+“Micromegas,” all the inhabitants are proportionately tall and
+proportionately long-lived), discovered our own little solar system,
+and lighted on what we call the majestic planet Saturn, he
+was naturally astonished at the pettiness of everything compared
+with the world he had left. That the Saturnian inhabitants
+were in his eyes a race of mere dwarfs (they were only a
+mile high, instead of twenty-four miles like himself) did not
+make them contemptible to his philosophic mind, for he reflected
+that such little creatures might still think and reason; but when
+he learned that these puny beings were also correspondingly
+short-lived, and passed but fifteen thousand years between the<span class="pagenum" id="Page_224">224</span>
+cradle and the grave, he could not but agree that this was like
+dying as soon as one was born, that their life was but a span,
+and their globe an atom. Yet it seems that when one of these
+very Saturnian dwarfs came afterward with him to our own little
+ball, and by the aid of a microscope discovered certain animalculæ
+on its surface, and even held converse with two of them,
+he could not in turn make up his own mind that intelligence
+could inhere in such invisible insects, till one of them (it was an
+astronomer with his sextant) measured his height to an inch, and
+the other, a divine, expounded to him the theology of some of
+these mites, according to which all the heavenly host, including
+Saturn and Sirius itself, were created for <em>them</em>.</p>
+
+<p>Do not let us hold this parable as out of place here, for what
+use is it to write down a long series of figures expressing the
+magnitude of other worlds, if it leave us with the old sense
+of the importance to creation of our own; and what use to
+describe their infinite number to a human mite who reads, and
+remains of the opinion that <em>he</em> is the object they were all
+created for?</p>
+
+<p>Above us are millions of suns like ours. The Milky Way
+(shown on page 225) spreads among them, vague and all-surrounding,
+as a type of the infinities yet unexplored, and of
+the world of nebulæ of which we still know so little. Let us
+say at once that it is impossible here to undertake the description
+of the discoveries of the New Astronomy in this region, for we
+can scarcely indicate the headings of the chapters which would
+need to be written to describe what is most important.</p>
+
+<div id="ip_87" class="figcenter" style="max-width: 29em;">
+  <img src="images/i_225.jpg" alt="" />
+  <div class="caption">FIG. 87.—THE MILKY WAY. (FROM A STUDY BY E. L. TROUVELOT).</div></div>
+
+<p>The first of these chapters (if we treated our subjects in the
+order of distance) would be one on space itself, and our changed
+ideas of the void which separates us from the stars. Of this we
+will only say in passing, that the old term “the temperature of
+space” has been nearly abrogated; for while it used to be supposed
+that more than half of the heat which warmed the earth<span class="pagenum" id="Page_227">227</span>
+came from this mysterious “space” or from the stars, it is now
+recognized that the earth is principally warmed only by the sun.
+Of the contents of the region between the earth and the stars,
+we have, it must be admitted, still little but conjecture; though
+perhaps that conjecture turns more than formerly to the idea that
+the void is not a real void, but that it is occupied by something
+which, if highly attenuated, is none the less matter, and something
+other and more than the mere metaphysical conception of
+a vehicle to transmit light to us.</p>
+
+<p>Of the stars themselves, we should need another chapter to
+tell what has been newly learned as to their color and light,
+even by the old methods, that is, by the eye and the telescope
+alone; but if we cannot dwell on this, we must at least refer,
+however inadequately, to what American astronomers are doing
+in this department of the New Astronomy, and first in the photometry
+of the stars, which has assumed a new importance of
+late years, owing to the labors carried on in this department at
+Cambridge.</p>
+
+<p>That one star differs from another star in glory we have long
+heard, but our knowledge of physical things depends largely on
+our ability to answer the question, “how much?” and the value
+of this new work lies in the accuracy and fulness of its measures;
+for in this case the whole heavens visible from Cambridge to
+near the southern horizon have been surveyed, and the brightness
+of every naked-eye star repeatedly measured, so that all
+future changes can be noted. This great work has taxed the
+resources of a great observatory, and its results are only to be
+adequately valued by other astronomers; but Professor Pickering’s
+own investigations on variable stars have a more popular
+interest. It is surely an amazing fact that suns as large or
+larger than our own should seem to dwindle almost to extinction,
+and regain their light within a few days or even hours;
+yet the fact has long been known, while the cause has remained<span class="pagenum" id="Page_228">228</span>
+a mystery. A mystery, in most cases, it remains still; but in
+some we have begun to get knowledge, as in the well-known
+instance of Algol, the star in the head of Medusa. Here it has
+always been thought probable that the change was due to something
+coming between us and the star; but it is on this very
+account that the new investigation is more interesting, as showing
+how much can be done on an old subject by fresh reasoning
+alone, and how much valuable ore may lie in material which has
+already been sifted. The discussion of the subject by Professor
+Pickering, apart from its elevated aim, has if, in its acute analysis
+only, the interest belonging to a story where the reader first sees
+a number of possible clews to some mystery, and then the
+gradual setting aside, one by one, of those which are only loose
+ends, and the recognition of the real ones which lead to the
+successful solution. The skill of the novelist, however, is
+more apparent than real, since the riddle he solves for us is
+one he has himself constructed, while here the enigma is of
+Nature’s propounding; and if the solution alone were given
+us, the means by which it is reached would indeed seem to
+be inexplicable.</p>
+
+<p>This is especially so when we remember what a point there
+is to work on, for the whole system reasoned about, though it
+may be larger than our own, is at such a distance that it appears,
+literally and exactly, far smaller to the eye than the point
+of the finest sewing-needle; and it is a course of accurate reasoning,
+and reasoning alone, on the character of the observed
+changing brightness of this point, which has not only shown the
+existence of some great dark satellite, but indicated its size, its
+distance from its sun, its time of revolution, the inclination of
+its orbit, and still more. The existence of dark invisible bodies
+in space, then, is in one case at least demonstrated, and in this
+instance the dark body is of enormous size; for, to illustrate by
+our own solar system, we should probably have to represent it<span class="pagenum" id="Page_229">229</span>
+in imagination by a planet or swarm of planetoids hundreds of
+times the size of Jupiter, and (it may be added) whirling around
+the sun at less than a tenth the distance of Mercury.</p>
+
+<p>Of a wholly different class of variables are those which have
+till lately only been known at intervals of centuries, like that
+new star Tycho saw in 1572. I infer from numerous inquiries
+that there is such a prevalent popular notion that the “Star of
+Bethlehem” may be expected to show itself again at about the
+present time, that perhaps I may be excused for answering these
+questions in the present connection.</p>
+
+<p>In the first place, the idea is not a new, but a very old one,
+going back to the time of Tycho himself, who disputed the
+alleged identity of his star with that which appeared to the shepherds
+at the Nativity. The evidence relied on is, that bright
+stars are said to have appeared in this constellation repeatedly at
+intervals of from three hundred and eight to three hundred and
+nineteen years (though even this is uncertain); and as the mean
+of these numbers is about three hundred and fourteen, which
+again is about one-fifth of 1572 (the then number of years from
+the birth of Christ), it has been suggested, in support of the old
+notion, that the Star of Bethlehem might have been a variable,
+shining out every three hundred and fourteen or three hundred
+and fifteen years, whose fifth return would fall in with the appearance
+that Tycho saw, and whose <em>sixth</em> return would come in
+1886 or 1887. This is all there is about it, and there is nothing
+like evidence, either that this was the star seen by the Wise
+Men, or that it is to be seen again by us. On the other hand,
+nothing in our knowledge, or rather in our ignorance, authorizes
+us to say positively it cannot come again; and it may be stated
+for the benefit of those who like to believe in its speedy return,
+that if it does come, it will make its appearance some night in
+the northern constellation of Cassiopeia’s chair, the position
+originally determined by Tycho at its last appearance, being<span class="pagenum" id="Page_230">230</span>
+twenty-eight degrees and thirteen minutes from the pole, and
+twenty-six minutes in right ascension.</p>
+
+<p>We were speaking of these new stars as having till lately
+only appeared at intervals of centuries; but it is not to be inferred
+that if they now appear oftener it is because there are
+more of them. The reason is, that there are more persons looking
+for them; and the fact is recognized that, if we have observers
+enough and look closely enough, the appearance of
+“new stars” is not so very rare a phenomenon. Every one at
+all interested in such matters remembers that in 1866 a new star
+broke out in the Northern Crown so suddenly that it was shining
+as bright as the Polar Star, where six hours before there had
+been nothing visible to the eve. Now all stars are not as large
+as our sun, though some are much larger; but there are circumstances
+which make it improbable that this was a small or near
+object, and it is well remembered how the spectroscope showed
+the presence of abnormal amounts of incandescent hydrogen, the
+material which is perhaps the most widely diffused in the universe
+(and which is plentiful, too, in our own bodies), so that
+there was some countenance to the popular notion that this was
+a world in flames. We were, at any rate, witnessing a catastrophe
+which no earthly experience can give us a notion of, in a
+field of action so remote that the flash of light which brought the
+news was unknown years on the way, so that all this—strange
+but now familiar thought—occurred long before we <em>saw</em> it
+happen. The star faded in a few days to invisibility to the
+naked eye, though not to the telescope; and, in fact, all these
+phenomena at present appear rather to be enormous and sudden
+enlargements of the light of existing bodies than the creation of
+absolutely new ones; while of these “new stars” the examples
+may almost be said to be now growing numerous, two having appeared
+in the last two years.</p>
+
+<p>Not to enlarge, then, on this chapter of photometry, let us<span class="pagenum" id="Page_233">233</span>
+add, in reference to another department of stellar astronomical
+work, that the recognized master in the study of double stars the
+world over is not an astronomer by profession, at the head of
+some national observatory in Berlin or Paris, but a stenographer
+in the Chicago law-courts, Mr. W. S. Burnham, who, after his
+day’s duties, by nightly labor, prolonged for years with the small
+means at an amateur’s command, has perhaps added more to our
+knowledge of his special subject in ten years than all other living
+astronomers.</p>
+
+<div id="ip_88" class="figcenter" style="max-width: 32em;">
+  <img src="images/i_231.jpg" alt="" />
+  <div class="caption">FIG. 88.—SPECTRA OF STARS IN PLEIADES.</div></div>
+
+<p>We have here only alluded to the spectroscope in its application
+to stellar research, and we cannot now do more than to
+note the mere headlines of the chapters that should be written
+on it.</p>
+
+<p>First, there is the memorable fact that, after reaching across
+the immeasurable distances, we find that the stars are like <em>us</em>,—like
+in their ultimate elements to those found in our own sun,
+our own earth, our own bodies. Any fuller view of the subject
+than that which we here only indicate, would begin with
+the evidence of this truth, which is perhaps on the whole the
+most momentous our science has brought us, and with which no
+familiarity should lessen our wonder, or our sense of its deep
+and permanent significance.</p>
+
+<p>Next, perhaps, we should understand that, invading the province
+of the Old Astronomy, the spectroscope now tells us of the
+motions of these stars, which we cannot see move,—motions in
+what we have always called the “fixed” stars, to signify a state
+of fixity to the human eye, which is such, that to it at the close
+of the nineteenth century they remain in the same relative positions
+that they occupied when that eye first looked on them, in
+some period long before the count of centuries began.</p>
+
+<p>In perhaps the earliest and most enduring work of man’s
+hands, the great pyramid of Egypt, is a long straight shaft, cut
+slopingly through the solid stone, and pointing, like a telescope,<span class="pagenum" id="Page_234">234</span>
+to the heavens near the pole. If we look through it now we
+see—nothing; but when it was set up it pointed to a particular
+star which is no longer there. That pyramid was built when
+the savages of Britain saw the Southern Cross at night; and the
+same slow change in the direction of the earth’s axis, that in
+thousands of years has borne that constellation to southern
+skies, has carried the stone tube away from the star that it
+once pointed at. The actual motion of the star itself, relatively
+to our system, is slower yet,—so inconceivably slow that we
+can hardly realize it by comparison with the duration of the
+longest periods of human history. The stone tube was pointed
+at the star by the old Egyptians, but “Egypt itself is now become
+the land of obliviousness, and doteth. Her ancient civility
+is gone, and her glory hath vanished as a phantasma. She
+poreth not upon the heavens, astronomy is dead unto her, and
+knowledge maketh other cycles. Canopus is afar off, Memnon
+resoundeth not to the Sun, and Nilus heareth strange voices.”
+In all this lapse of ages, the star’s own motion could not have so
+much as carried it across the mouth of the narrow tube. Yet a
+motion to or from us of this degree, so slow that the unaided eve
+could not see it in thousands of years of watching, the spectroscope,
+first efficiently in the hands of the English astronomer,
+Dr. Huggins, and later in those of Professor Young of Princeton,
+not only reveals at a look, but tells us the amount and direction
+of it, in a way that is as strange and unexpected, in the view of
+our knowledge a generation ago, as its revelation of the essential
+composition of the bodies themselves.</p>
+
+<div id="ip_89" class="figcenter" style="max-width: 49em;">
+  <img src="images/i_235.jpg" alt="" />
+  <div class="caption">FIG. 89.—SPECTRUM OF ALDEBARAN.</div></div>
+
+<div id="ip_90" class="figcenter" style="max-width: 50em;">
+  <img src="images/i_235b.jpg" alt="" />
+  <div class="caption">FIG. 90.—SPECTRUM OF VEGA.</div></div>
+
+<p>Again, in showing us this composition, it has also shown us
+more, for it has enabled us to form a conjecture as to the relative
+ages of the stars and suns; and this work of classifying them,
+not only according to their brightness, but each after his kind,
+we may observe was begun by a countryman of our own, Mr.
+Rutherfurd, who seems to have been among the first after<span class="pagenum" id="Page_235">235</span>
+Fraunhofer to apply
+the newly-invented instrument
+to the stars,
+and quite the first to
+recognize that these
+were, broadly speaking,
+divisible into a few
+leading types, depending
+not on their size
+but on their essential
+nature. After him Secchi
+(to whom the first
+conception is often
+wrongly attributed)
+developed it, and gave
+four main classes into
+which the stars are in
+this way divisible, a
+classification which has
+been much extended by
+others; while the first
+carefully delineated
+spectra were those of
+Dr. Huggins, who has
+done so much for all
+departments of our science
+that in a fuller
+account his name would
+reappear in every chapter
+of this New Astronomy,
+and than whom
+there is no more eminent
+living example of
+its study. Owing to
+their feeble light, years<span class="pagenum" id="Page_236">236</span>
+were needed when he began his work to depict completely so
+full a single spectrum as that he gives of Aldebaran, though
+he has lived to see stellar spectrum photography, whose use
+he first made familiar, producing in its newest development,
+which we give here, the same result in almost as many minutes.
+Before we present this latest achievement of celestial
+photography, let us employ the old method of an engraving
+made from eye-drawings, once more, to illustrate on page 222
+the distinct character of these spectra, and their meaning. In
+the telespectroscope, the star is drawn out into a band of colored
+light, but here we note only in black and white the lines which
+are seen crossing it, the red end in these drawings being at the
+left, and the violet at the right; and we may observe of this
+illustration, that though it may be criticised by the professional
+student, and though it lack to the general reader the attraction
+of color, or of beautiful form, it is yet full of interest to any one
+who wishes to learn the meaning of the message the star’s light
+can be made to yield through the spectroscope, and to know
+how significant the differences are it indicates between one star
+and another, where all look so alike to the eye. First is the
+spectrum of a typical white or blue-white star, Sirius,—the very
+brightest star in the sky, and which we all know. The brighter
+part of the spectrum is a nearly continuous ribbon of color,
+crossed by conspicuous, broad, dark lines, exactly corresponding
+in place to narrower ones in our sun, and due principally to
+hydrogen. Iron and magnesium are also indicated in this class,
+but by too fine lines to be here shown.</p>
+
+<p>Sirius, as will be presently seen, belongs to the division of
+stars whose spectrum indicates a very high temperature, and in
+this case, as in what follows, we may remark (to use in part Mr.
+Lockyer’s words) that one of the most important distinctions
+between the stars in the heavens is one not depending upon
+their mass or upon anything of that kind, but upon conditions<span class="pagenum" id="Page_237">237</span>
+which make their spectra differ, just in the way that in our
+laboratories the spectrum of one and the same body will differ
+at different temperatures.</p>
+
+<p>What these absolutely are in the case of the stars, we may
+not know; but placing them in their most probable relative
+order, we have taken as an instance of the second class, or
+lower-temperature stage, our own sun. The impossibility of
+giving a just notion of its real complexity may be understood,
+when we state that in the recent magnificent photographs by
+Professor Rowland, a part alone of this spectrum occupies something
+like fifty times the space here given to the whole, so that,
+crowded with lines as this appears, scarcely one in fifty of those
+actually visible can be given in it. Without trying to understand
+all these now, let us notice only the identity of two
+or three of its principal elements with those found in other
+stars, as shown by the corresponding identity of some leading
+lines. Thus, C and F (with others) are known to be caused by
+hydrogen; D, by sodium; <i>b</i>, by magnesium; while fainter
+lines are given by iron and by other substances. These
+elements can be traced by their lines in most of the different
+star-spectra on this plate, and all those named are constituents
+of our own frames.</p>
+
+<p>The hydrogen lines are not quite accurately shown in the
+plate from which our engraving is made, those in Sirius, for
+instance, being really wider by comparison than they are here
+given; and we may observe in this connection, that by the particular
+appearance such lines wear in the spectrum itself we can
+obtain some notion of the <em>mass</em> of a star, as well as of its chemical
+constitution. We can compare the essential characteristics
+of such bodies, then, without reference to their apparent size, or
+as though they were all equally remote; and it is a striking
+thought, that when we thus rise to an impartial contemplation
+of the whole stellar universe, our sun, whose least ray makes the<span class="pagenum" id="Page_238">238</span>
+whole host of stars disappear, is found to be not only itself a
+star, but by comparison a small one,—one at least which is
+more probably below than above the average individual of its
+class, while some, such as Sirius, are not impossibly hundreds of
+times its size.</p>
+
+<p>Then comes a third class, such as is shown in the spectrum of
+the brightest star in Orion, looking still a little like that of our
+sun; but yet more distinctively in that of the brightest star in
+Hercules, looking like a columnar or fluted structure, and concerning
+which the observations of Lockyer and others create the
+strong presumption, not to say certainty, that we have here a
+lower temperature still. Antares and other reddish stars belong
+to this division, which in the very red stars passes into the fourth
+type, and there are more classes and subclasses without end; but
+we invite here attention particularly to the first three, much as
+we might present a child, an adult, and an old man, as types of
+the stages of human existence, without meaning to deny that
+there are any number of ages between. We can even say that
+this may be something more than a mere figure of speech,
+and that a succession in age is not improbably pointed at in
+these types.</p>
+
+<div id="ip_91" class="figcenter" style="max-width: 35em;">
+  <img src="images/i_239.jpg" alt="" />
+  <div class="caption">FIG. 91.—GREAT NEBULA IN ORION. (FROM A PHOTOGRAPH BY A. A. COMMON, F. R. S.)</div></div>
+
+<p>We may have considered—perhaps not without a sort of
+awe at the vastness of the retrospect—the past life of the
+worlds of our own system, from our own globe of fluid fire as
+we see it by analogy in the past, through the stages of planetary
+life to the actual condition of our present green earth, and
+on to the stillness of the moon. Yet the life history of our sun,
+we can hardly but admit, is indefinitely longer than this. We
+feel, rather than comprehend, the vastness of the period that
+separates our civilization from the early life of the world; but
+what is this to the age of the sun, which has looked on and seen
+its planetary children grow? Yet if we admit this temperature
+classification of the stars, we are not far from admitting that the<span class="pagenum" id="Page_241">241</span>
+spectroscope is now pointing out the stages in the life of suns
+themselves; suns just beginning their life of almost infinite
+years; suns in the middle of their course; suns which are growing
+old and casting feebler beams,—all these and many more it
+brings before us.</p>
+
+<p>Another division of our subject would, with more space, include
+a fuller account of that strange and most interesting
+development of photography which is going on even while we
+write; and this is so new and so important, that we must try to
+give some hint of it even in this brief summary, for even since
+the first numbers of this series were written, great advances have
+taken place in its application to celestial objects.</p>
+
+<p>Most of us have vague ideas about small portions of time; so
+much so, that it is rather surprising to find to how many intelligent
+people, a second, as seen on the clock face, is its least
+conceivable interval. Yet a second has not only a beginning,
+middle, and end, as much as a year has, but can, in thought at
+least, be divided into just as many numbered parts as a year
+can. Without entering on a disquisition about this, let us try
+to show by some familiar thing that we can at any rate not
+only divide a second in imagination into, let us say, a hundred
+parts, but that we can observe distinctly what is happening in
+such a short time, and make a picture of it,—a picture which
+shall be begun and completed while this hundredth of a second
+lasts.</p>
+
+<p>Every one has fallen through at least some such a little distance
+as comes in jumping from a chair to the floor, and most of
+us, it is safe to say, have a familiar impression of the fact that it
+takes, at any rate, less than a second in such a case from the
+time the foot leaves its first support till it touches the ground.
+Plainly, however large or small the fall may be, each fraction of
+an inch of it must be passed through in succession, and if we
+suppose the space to be divided, for instance, into a hundred<span class="pagenum" id="Page_242">242</span>
+parts, we must divide in thought the second into at least as
+many, since each little successive space was traversed in its own
+little interval of time, and the whole together did not make a
+second. We can even, as a matter of fact, very easily calculate
+the time that it will take anything which has already fallen, let
+us say one foot, to fall an inch more; and we find this, in the
+supposed instance, to be almost exactly one one-hundredth of a
+second. On page 243 is a reproduction of a photograph from
+Nature, of a man falling freely through the air. He has dropped
+from the grasp of the man above him, and has already fallen
+through some small distance,—a foot or so. If we suppose it
+to be a foot, since we can see that the man’s features are not
+blurred, as they would undoubtedly have been had he moved
+even much less than an inch while this picture was being taken,
+it follows, from what has been said, that the making of the whole
+picture—landscape, spectators, and all—occupied not <em>over</em> one
+one-hundredth of a second.</p>
+
+<p>We have given this view of “the falling man” because,
+rightly understood, it thus carries internal evidence of the limit
+of time in which it could have been made; and this will serve as
+an introduction to another picture, where probably no one will
+dispute that the time was still shorter, but where we cannot give
+the same kind of evidence of the fact.</p>
+
+<p>“Quick as lightning” is our common simile for anything occupying,
+to ordinary sense, no time at all. Exact measurements
+show that the electric spark does occupy a time, which is almost
+inconceivably small, and of which we can only say here that the
+one one-hundredth of a second we have just been considering is
+a long period by comparison with the duration of the brightest
+portion of the light.</p>
+
+<div id="ip_92" class="figcenter" style="max-width: 19em;">
+  <img src="images/i_243.jpg" alt="" />
+  <div class="caption">FIG. 92.—A FALLING MAN.</div></div>
+
+<p>On page 245 we have the photograph of a flash of lightning
+(which proves to be several simultaneous flashes), taken last
+July from a point on the Connecticut coast, and showing not<span class="pagenum" id="Page_243">243</span>
+only the vivid zigzag streaks of the lightning itself, but something
+of the distant sea view, and the masts of the coast survey
+schooner “Palinurus” in the foreground, relieved against the sky.
+We are here concerned with this interesting autograph of the<span class="pagenum" id="Page_244">244</span>
+lightning, only as an illustration of our subject, and as proving
+the almost infinite sensitiveness of the recent photographic processes;
+for there seems to be no limit to the briefness of time
+in which, these can so act in some degree, whether the light
+be bright or faint, and no known limit to the briefness of
+time required for them to act <em>effectively</em> if the light be bright
+enough.</p>
+
+<p>What has just preceded will now help us to understand how
+it is that photography also succeeds so well in the incomparably
+fainter objects we are about to consider, and which have been
+produced not by short but by long exposures. We have just
+seen how sensitive the modern plate is, and we are next to notice
+a new and very important point in which photographic action in
+general differs remarkably from that of the eye. Seeing may be
+described, not wholly inaptly, as the recognition of a series of
+brief successive photographs, taken by the optic lens on the
+retina; but the important difference between seeing and photographing,
+which we now ask attention to, is this: When the eye
+looks at a faint object, such as the spectrum of a star, or at the
+still fainter nebula, this, as we know, appears no brighter at
+the end of half an hour than at the end of the first half-second.
+In other words, after a brief fraction of a second, the visual effect
+does not sensibly accumulate. But in the action of the photograph,
+on the contrary, the effect <em>does</em> accumulate, and in the
+case of a weak light accumulates indefinitely. It is owing to
+this precious property, that supposing (for illustration merely)
+the lightning flash to have occupied the one-thousandth part of a
+second in impressing itself on the plate, to get a nearly similar
+effect from a continuous light one thousand times weaker, we
+have only to expose the ¡date a thousand times as long, that is,
+for one second; while from a light a million times weaker we
+should get the same result by exposing it a million times as
+long, that is, for a thousand seconds.</p>
+
+<p><span class="pagenum" id="Page_245">245</span></p>
+
+<p>And now that we come to the stars, whose spectra occupy
+minutes in taking, what we just considered will help us to
+understand how we can advantageously thus pass from a
+thousandth of a second or less, to one thousand seconds or
+even more, and how we can even,—given time enough,—conceivably,
+be able to photograph what the eye <em>cannot see
+at all</em>.</p>
+
+<div id="ip_93" class="figcenter" style="max-width: 32em;">
+  <img src="images/i_245.jpg" alt="" />
+  <div class="caption">FIG. 93.—A FLASH OF LIGHTNING. (FROM A PHOTOGRAPH BY DR. H. G. PIFFARD.)</div></div>
+
+<p>We have on page 231 a photograph quite recently taken at
+Cambridge from a group of stars (the Pleiades) passing by the
+telescope. Every star is caught as it goes, and presented, not in
+its ordinary appearance to the eye, but by its spectrum. There
+is a general resemblance in these spectra from the same cluster;
+while in other cases the spectra are of all types and kinds, the
+essential distinction between individuals alike to the eve, being<span class="pagenum" id="Page_246">246</span>
+more strikingly shown, as stars apparently far away from one
+another are seen to have a common nature, and stars looking
+close together (but which may be merely in line, and really far
+apart) have often no resemblance; and so the whole procession
+passes through the field of view, each individual leaving its own
+description. This self-description will be better seen in the remarkable
+photographs of the spectra of Vega and Aldebaran,
+which are reproduced on page 235 from the originals by a process
+independent of the graver. They were obtained on the
+night of November 9, 1886, at Cambridge, as a part of the work
+pursued by Professor Pickering, with means which have been
+given from fitting hands, thus to form a memorial of the late Dr.
+Henry Draper. We are obliged to the source indicated, then,
+for the ability to show the reader here the latest, and as yet inedited,
+results in this direction; and they are such as fully to
+justify the remark made above, that minutes, by this new process,
+take the place of years of work by the most skilful astronomer’s
+eye and hand.</p>
+
+<p>The spectrum of Vega (Alpha Lyræ) is marked only by a
+few strong lines, due chiefly to hydrogen, because these are all
+there are to be seen in a star of its class. Aldebaran (the bright
+star in Taurus), on the contrary, here announces itself as belonging
+to the family of our own sun, a probably later type, and distinguished
+by solar-like lines in its spectrum, which may be
+counted in the original photograph to the number of over two
+hundred. There is necessarily some loss in the printed reproduction;
+but is it not a wonderful thing, to be able to look up,
+as the reader may do, to Aldebaran in the sky, and then down
+upon the page before us, knowing that that remote, trembling
+speck of light has by one of the latest developments of the New
+Astronomy been made, without the intervention of the graver’s
+hand, to write its own autograph record on the page before
+him?</p>
+
+<p><span class="pagenum" id="Page_247">247</span></p>
+
+<p>In the department of nebular astronomy, photography has
+worked an equal change. The writer well remembers the weeks
+he has himself spent in drawing or attempting to draw nebulæ,—things
+often so ghost-like as to disappear from view every time
+the eye turned from the white paper, and only to be seen again
+when it had recovered its sensitiveness by gazing into the darkness.
+The labors of weeks were, literally, only represented by
+what looked like a stain on the paper; and no two observers,
+however careful, could be sure that the change between two
+drawings of a nebula at different dates was due to an alteration
+in the thing itself, or in the eye or hand of the observer, though
+unfortunately for the same reason it is impossible fully to render
+the nebulous effect of the photograph in engraving. We cannot
+with our best efforts, then, do full justice to the admirable one
+of Orion, on page 239, which we owe to the particular kindness
+of Mr. Common, of Ealing, England, whose work in this
+field is as yet unequalled. The original enlargement measures
+nearly two square feet in area, with fine definition. It is
+taken by thirty-nine minutes’ exposure, and its character can
+only be indicated here; for it is not too much to say here
+of this original also, that as many years of the life of the most
+skilled artist could not produce so trustworthy a record of this
+wonder.</p>
+
+<p>The writer remembers the interest with which he heard Dr.
+Draper, not long before his lamented death, speak of the almost
+incredible sensitiveness of these most recent photographic processes,
+and his belief that we were fast approaching the time
+when we should photograph what we could not even see. That
+time has now arrived. At Cambridge, in Massachusetts, and at
+the Paris Observatory, by taking advantage of the cumulative
+action we have referred to, and by long exposures, photographs
+have recently been taken showing stars absolutely invisible to
+the telescope, and enabling us to discover faint nebulæ whose<span class="pagenum" id="Page_248">248</span>
+previous existence had not been suspected; and when we consider
+that an hour’s exposure of a plate, now not only secures
+a fuller star-chart than years of an astronomer’s labor, but a
+more exact one, that the art is every month advancing perceptibly
+over the last, and that it is already, as we may say,
+not only making pictures of what we see, but of what
+we cannot see even with the telescope,—we have before us
+a prospect whose possibilities no further words are needed to
+suggest.</p>
+
+<p>We have now, not described, but only mentioned, some division
+of the labors of the New Astronomy in its photometric,
+spectroscopic, and photographic stellar researches, on each of
+which as many books, rather than chapters, might be written, to
+give only what is novel and of current interest. But these are
+themselves but a part of the modern work that has overturned
+or modified almost every conception about the stellar universe
+which was familiar to the last generation, or which perhaps we
+were taught in our own youth.</p>
+
+<div class="tb">* * * * *</div>
+
+<p>In considering the results to be drawn from this glance we
+have taken at some facts of modern observation, if it be asked,
+not only what the facts are, but what lessons the facts themselves
+have to teach, there is more than one answer, for the
+moral of a story depends on the one who draws it, and we may
+look on our story of the heavens from the point of view either
+of our own importance or of our own insignificance. In the one
+case we behold the universe as a sort of reflex of our own
+selves, mirroring in vast proportions of time and space our own
+destiny; and even from this standpoint, one of the lessons of our
+subject is surely that there is no permanence in any created
+thing. When primitive man learned that with lapsing years the
+oak withered and the very rock decayed, more slowly but as
+surely as himself, he looked up to the stars as the types of<span class="pagenum" id="Page_249">249</span>
+contrast to the change he shared, and fondly deemed them
+eternal; but now we have found change there, and that probably
+the star clusters and the nebulæ, even if clouds of suns
+and worlds, are fixed only by comparison with our own brief
+years, and, tried by the terms of their own long existence, are
+fleeting like ourselves.</p>
+
+<div class="blockquot">
+
+<p>“We have often witnessed the formation of a cloud in a serene sky.
+A hazy point barely perceptible—a little wreath of mist increases in
+volume and becomes darker and denser, until it obscures a large portion
+of the heavens. It throws itself into fantastic shapes, it gathers a glory
+from the sun, is borne onward by the wind, and as it gradually came, so,
+perhaps, it gradually disappears, melting away in the untroubled air.
+But the universe is nothing more than such a cloud,—a cloud of suns
+and worlds. Supremely grand though it may seem to us, to the infinite
+and eternal intellect it is no more than a fleeting mist. If there be a
+succession of worlds in infinite space, there is also a succession of worlds
+in infinite time. As one after another cloud replaces clouds in the skies,
+so this starry system, the universe, is the successor of countless others
+that have preceded it,—the predecessor of countless others that will
+follow.”</p>
+</div>
+
+<p>These impressions are strengthened rather than weakened
+when we come back from the outer universe to our own little
+solar system; for every process which we know, tends to the
+dissipation, or rather the degradation, of heat, and seems to
+point, in our present knowledge, to the final decay and extinction
+of the light of the world. In the words of one of the most
+eminent living students of our subject, “The candle of the sun
+is burning down, and, as far as we can see, must at last reach
+the socket. Then will begin a total eclipse which will have no
+end.</p>
+
+<div class="poetry-container">
+<div class="poetry">
+  <div class="stanza">
+    <div class="verse indent0">‘Dies iræ, dies illa,</div>
+    <div class="verse indent0">Solvet sæclum in favilla.’”</div>
+  </div>
+</div>
+</div>
+
+<p>Yet though it may well be that the fact itself here is true, it
+is possible that we draw the moral to it, unawares, from an unacknowledged<span class="pagenum" id="Page_250">250</span>
+satisfaction in the idea of the vastness of the
+funeral pyre provided for such beings as ourselves, and that it
+is pride, after all, which suggests the thought that when the
+sun of the human race sets, the universe will be left tenantless,
+as a body from which the soul has fled. Can we not bring ourselves
+to admit that there may be something higher than man
+and more enduring than frail humanity, in some sphere in which
+<em>our</em> universe, conditioned as it is in space and time, is itself embraced;
+and so distrust the conclusions of man’s reason where
+they seem to flatter his pride?</p>
+
+<p>May we not receive even the teachings of science, as to the
+“Laws of Nature,” with the constant memory that all we know,
+even from science itself, depends on our very limited sensations,
+our very limited experience, and our still more limited
+power of conceiving anything for which this experience has
+not prepared us?</p>
+
+<div class="tb">* * * * *</div>
+
+<p>I have read somewhere a story about a race of ephemeral
+insects who live but an hour. To those who are born in the
+early morning the sunrise is the time of youth. They die of old
+age while his beams are yet gathering force, and only their descendants
+live on to midday; while it is another race which sees
+the sun decline, from that which saw him rise. Imagine the sun
+about to set, and the whole nation of mites gathered under the
+shadow of some mushroom (to them ancient as the sun itself) to
+hear what their wisest philosopher has to say of the gloomy
+prospect. If I remember aright, he first told them that, incredible
+as it might seem, there was not only a time in the world’s
+youth when the mushroom itself was young, but that the sun in
+those early ages was in the eastern, not in the western, sky.
+Since then, he explained, the eyes of scientific ephemera had followed
+it, and established by induction from vast experience the
+great “Law of Nature,” that it moved only westward; and he<span class="pagenum" id="Page_251">251</span>
+showed that since it was now nearing the western horizon, science
+herself pointed to the conclusion that it was about to disappear
+forever, together with the great race of ephemera for
+whom it was created.</p>
+
+<p>What his hearers thought of this discourse I do not remember,
+but I have heard that the sun rose again the next
+morning.</p>
+
+<hr />
+
+<div class="chapter"><div class="index">
+<p><span class="pagenum" id="Page_253">253</span></p>
+
+<h2 class="nobreak p1" id="INDEX">INDEX.</h2>
+
+<ul class="index">
+<li class="ifrst">Abbe, Professor, <a href="#Page_56">56</a>.</li>
+
+<li class="indx">Actinism, <a href="#Page_71">71</a>.</li>
+
+<li class="indx">Adams, Professor, <a href="#Page_195">195</a>.</li>
+
+<li class="indx">Africa, <a href="#Page_116">116</a>.</li>
+
+<li class="indx">Ages, stellar, <a href="#Page_238">238</a>.</li>
+
+<li class="indx"><a id="Air"></a>Air:</li>
+<li class="isub1">dancing, <a href="#Page_17">17</a>;</li>
+<li class="isub1">a medium, <a href="#Page_33">33</a>;</li>
+<li class="isub1">continuous, <a href="#Page_176">176</a>;</li>
+<li class="isub1">rarefied, <a href="#Page_179">179</a>;</li>
+<li class="isub1">motes, <a href="#Page_181">181</a>;</li>
+<li class="isub1">nimble, <a href="#Page_191">191</a>.</li>
+<li class="isub1">(See <i><a href="#Atmosphere">Atmosphere</a></i>.)</li>
+
+<li class="indx">Airless Mountains, <a href="#Page_160">160</a>.</li>
+
+<li class="indx">Air-wave, <a href="#Page_185">185</a>.</li>
+
+<li class="indx">Aitken’s Researches, <a href="#Page_181">181</a>.</li>
+
+<li class="indx">Alaska, <a href="#Page_38">38</a>.</li>
+
+<li class="indx">Aldebaran, <a href="#Page_222">222</a>, <a href="#Page_235">235</a>, <a href="#Page_236">236</a>, <a href="#Page_246">246</a>.</li>
+
+<li class="indx">Algot, <a href="#Page_228">228</a>.</li>
+
+<li class="indx"><a id="Allegheny"></a>Allegheny Observatory, <a href="#Page_17">17</a>, <a href="#Page_19">19</a>, <a href="#Page_84">84</a>, <a href="#Page_86">86</a>.</li>
+<li class="isub1">(See <i><a href="#Langley">Langley</a></i>.)</li>
+
+<li class="indx">Alphonsus Ring-plain, <a href="#Page_156">156</a>.</li>
+
+<li class="indx">Alps, <a href="#Page_39">39</a>, <a href="#Page_148">148</a>, <a href="#Page_151">151</a>, <a href="#Page_167">167</a>, <a href="#Page_181">181</a>.</li>
+<li class="isub1">(See <i><a href="#Lunar_Apennines">Apennines, Lunar</a></i>.)</li>
+
+<li class="indx"><a id="American_Astronomers"></a>American Astronomers, <a href="#Page_227">227</a>.</li>
+
+<li class="indx">American Continents, <a href="#Page_20">20</a>, <a href="#Page_20">21</a>, <a href="#Page_31">31</a>.</li>
+<li class="isub1">(See <i><a href="#South_America">South</a></i>.)</li>
+
+<li class="indx">Andalusia, <a href="#Page_53">53</a>.</li>
+
+<li class="indx">Animalculæ, <a href="#Page_224">224</a>.</li>
+
+<li class="indx"><a id="Animals"></a>Animals:</li>
+<li class="isub1">food, <a href="#Page_74">74</a>;</li>
+<li class="isub1">fright, <a href="#Page_42">42</a>.</li>
+<li class="isub1">(See <i><a href="#Dog">Dog</a></i>.)</li>
+
+<li class="indx">Antares, <a href="#Page_238">238</a>.</li>
+
+<li class="indx"><a id="Ants"></a>Ants, <a href="#Page_223">223</a>.</li>
+<li class="isub1">(See <i><a href="#Insects">Insects</a></i>.)</li>
+
+<li class="indx">Apennines, <a href="#Page_151">151</a>, <a href="#Page_152">153</a>, <a href="#Page_155">155</a>, <a href="#Page_160">160</a>, <a href="#Page_167">167</a>.</li>
+<li class="isub1">(See <i><a href="#Lunar_Alps">Alps, Lunar</a></i>.)</li>
+
+<li class="indx">Apples, <a href="#Page_171">171</a>.</li>
+
+<li class="indx"><a id="Arab_Traditions"></a>Arab Traditions, <a href="#Page_194">194</a>.</li>
+<li class="isub1">(See <i><a href="#Moslem">Moslem</a></i>.)</li>
+
+<li class="indx">Arago, quoted, <a href="#Page_41">41</a>, <a href="#Page_42">42</a>.</li>
+
+<li class="indx">Archimedes, <a href="#Page_94">94</a>.</li>
+
+<li class="indx">Archimedes Crater, <a href="#Page_151">151–153</a>, <a href="#Page_155">155</a>.</li>
+
+<li class="indx">Arctic Cold, <a href="#Page_159">159</a>.</li>
+
+<li class="indx">Arctic Pole, <a href="#Page_96">96</a>.</li>
+
+<li class="indx">Arcturus, <a href="#Page_208">208</a>, <a href="#Page_211">211</a>.</li>
+
+<li class="indx">Aristillus Crater, <a href="#Page_151">151</a>.</li>
+
+<li class="indx">Aristotelian Philosophy, <a href="#Page_8">8</a>.</li>
+
+<li class="indx">Arzachel, <a href="#Page_156">156</a>, <a href="#Page_160">161</a>.</li>
+
+<li class="indx">Asteroids, <a href="#Page_128">128</a>.</li>
+
+<li class="indx">Astrology, <a href="#Page_127">127</a>.</li>
+
+<li class="indx">Astronomers and Priests, <a href="#Page_1">1–3</a>.</li>
+<li class="isub1">(See <i><a href="#American_Astronomers">American, New</a></i>, <i><a href="#Old_Astronomy">Old</a></i>.)</li>
+
+<li class="indx">Astronomical Day, <a href="#Page_85">85</a>, <a href="#Page_86">86</a>.</li>
+
+<li class="indx"><a id="Atmosphere"></a>Atmosphere, <a href="#Page_136">136</a>, <a href="#Page_180">180</a>;</li>
+<li class="isub1">as a shield, <a href="#Page_216">216</a>, <a href="#Page_220">220</a>.</li>
+<li class="isub1">(See <i><a href="#Air">Air</a></i>.)</li>
+
+<li class="indx">Atolls, <a href="#Page_152">152</a>.</li>
+
+<li class="indx">Auger, simile, <a href="#Page_31">31</a>.</li>
+
+<li class="indx">Aurora Borealis, <a href="#Page_35">35</a>, <a href="#Page_67">67</a>, <a href="#Page_212">212</a>.</li>
+
+<li class="indx">Autolycus Crater, <a href="#Page_151">151</a>.</li>
+
+<li class="indx">Axis, <a href="#Page_9">9</a>, <a href="#Page_10">10</a>.</li>
+
+<li class="ifrst">Babel, <a href="#Page_96">96</a>.</li>
+
+<li class="indx">Bain Telegraph, <a href="#Page_88">88</a>.</li>
+
+<li class="indx">Balloons, <a href="#Page_176">176</a>.</li>
+
+<li class="indx"><a id="Bees"></a>Bees, <a href="#Page_124">124</a>.</li>
+<li class="isub1">(See <i><a href="#Insects">Insects</a></i>.)</li>
+
+<li class="indx">Berkeley’s Theory, <a href="#Page_70">70</a>.</li>
+
+<li class="indx">Berlin Observatory, <a href="#Page_233">233</a>.</li>
+
+<li class="indx">Bernières’s Lens, <a href="#Page_103">103</a>.</li>
+
+<li class="indx">Bessemer Steel, <a href="#Page_104">104–108</a>.</li>
+
+<li class="indx">Birds, <a href="#Page_172">172</a>, <a href="#Page_196">196</a>, <a href="#Page_197">197</a>.</li>
+<li class="isub1">(See <i><a href="#Animals">Animals</a></i>.)</li>
+
+<li class="indx">Black Hole, <a href="#Page_73">73</a>.</li>
+
+<li class="indx">Bond, Professor, <a href="#Page_204">204</a>.</li>
+
+<li class="indx">Boston, Mass., <a href="#Page_88">88</a>, <a href="#Page_132">132</a>.</li>
+
+<li class="indx">Bothkamp, observations at, <a href="#Page_66">66</a>.</li>
+
+<li class="indx"><a id="Breadstuffs"></a>Breadstuffs, <a href="#Page_78">78</a>, <a href="#Page_79">79</a>.</li>
+<li class="isub1">(See <i><a href="#Grain">Grain</a></i>, <i><a href="#Sun-spots">Sun-spots</a></i>, <i><a href="#Wheat">Wheat</a></i>.)</li>
+
+<li class="indx">Bridges, <a href="#Page_20">20</a>, <a href="#Page_68">68</a>.</li>
+
+<li class="indx"><a id="Britain_Ancient"></a>Britain, Ancient, <a href="#Page_1">1</a>, <a href="#Page_234">234</a>.</li>
+<li class="isub1">(See <i><a href="#England">England</a></i>.)</li>
+
+<li class="indx">British Isles, <a href="#Page_14">14</a>, <a href="#Page_25">25</a>.</li>
+
+<li class="indx"><a id="Brocken_Spectre"></a>Brocken Spectre, <a href="#Page_55">55</a>.<span class="pagenum" id="Page_254">254</span></li>
+
+<li class="indx">Brothers, Mr., <a href="#Page_50">50</a>.</li>
+
+<li class="indx">Bubbles, <a href="#Page_168">168</a>.</li>
+
+<li class="indx">Buffer, the air as a, <a href="#Page_216">216</a>, <a href="#Page_220">220</a>.</li>
+
+<li class="indx">Bunsen’s Researches, <a href="#Page_12">12</a>.</li>
+
+<li class="indx">Burnham, W. S., <a href="#Page_233">233</a>.</li>
+
+<li class="indx">Burning-glasses, <a href="#Page_102">102–104</a>.</li>
+
+<li class="indx">Burning Heat, <a href="#Page_160">160</a>, <a href="#Page_163">163</a>.</li>
+
+<li class="ifrst">Cactus, <a href="#Page_14">14</a>, <a href="#Page_24">24</a>.</li>
+
+<li class="indx">Calcutta, <a href="#Page_73">73</a>.</li>
+
+<li class="indx">California, <a href="#Page_151">151</a>, <a href="#Page_180">180</a>.</li>
+
+<li class="indx"><a id="Cambric_Needle"></a>Cambric Needle (<abbr>q. v.</abbr>), experiment, <a href="#Page_132">132</a>.</li>
+
+<li class="indx">Cambridge Observations, <a href="#Page_227">227</a>, <a href="#Page_245">245–247</a>.</li>
+
+<li class="indx">Camera Obscura, <a href="#Page_63">63</a>.</li>
+
+<li class="indx">Campanus Crater, <a href="#Page_163">163</a>, <a href="#Page_164">165</a>.</li>
+
+<li class="indx">Candle, simile, <a href="#Page_39">39</a>.</li>
+
+<li class="indx"><a id="Cannon-ball"></a>Cannon-ball, <a href="#Page_5">5</a>, <a href="#Page_38">38</a>, <a href="#Page_41">41</a>, <a href="#Page_98">98</a>, <a href="#Page_135">135</a>, <a href="#Page_186">186</a>, <a href="#Page_211">211</a>.</li>
+
+<li class="indx">Canopus, <a href="#Page_234">234</a>.</li>
+
+<li class="indx">Carbon, <a href="#Page_72">72</a>, <a href="#Page_73">73</a>, <a href="#Page_107">107</a>, <a href="#Page_221">221</a>.</li>
+
+<li class="indx">Carbonic-acid Gas, <a href="#Page_219">219</a>.</li>
+
+<li class="indx">Carpenter’s Studio, <a href="#Page_140">140</a>.</li>
+
+<li class="indx">Carrington’s Work, <a href="#Page_79">79</a>, <a href="#Page_87">87</a>.</li>
+
+<li class="indx">Carthage, <a href="#Page_116">116</a>.</li>
+
+<li class="indx">Cassini, <a href="#Page_42">42</a>.</li>
+
+<li class="indx">Cassiopeia, <a href="#Page_229">229</a>.</li>
+
+<li class="indx">Cataclysm, <a href="#Page_30">30</a>.</li>
+
+<li class="indx">Centimetres, <a href="#Page_93">93</a>.</li>
+
+<li class="indx">Chacornac’s Drawing, <a href="#Page_33">33</a>.</li>
+
+<li class="indx">Chambers, on sun-spots, <a href="#Page_80">80</a>.</li>
+
+<li class="indx"><a id="Charleston_Earthquake"></a>Charleston Earthquake (<abbr>q. v.</abbr>), <a href="#Page_42">42</a>.</li>
+
+<li class="indx">Chemical Elements, <a href="#Page_221">221</a>, <a href="#Page_223">223</a>.</li>
+
+<li class="indx">Cherry-stone, comparison, <a href="#Page_196">196</a>.</li>
+
+<li class="indx">Chicago:</li>
+<li class="isub1">great fire, <a href="#Page_134">134</a>;</li>
+<li class="isub1">astronomer, <a href="#Page_233">233</a>.</li>
+
+<li class="indx">China:</li>
+<li class="isub1">lens, <a href="#Page_103">103</a>, <a href="#Page_104">104</a>;</li>
+<li class="isub1">soil, <a href="#Page_180">180</a>.</li>
+
+<li class="indx">Chlorophyl, <a href="#Page_73">73</a>.</li>
+
+<li class="indx">Chocolate, simile, <a href="#Page_107">107</a>.</li>
+
+<li class="indx">Cholera, <a href="#Page_80">80</a>.</li>
+
+<li class="indx">Chromosphere, <a href="#Page_7">7</a>;</li>
+<li class="isub1">clouds, <a href="#Page_62">62</a>;</li>
+<li class="isub1">forms, <a href="#Page_64">64–68</a>.</li>
+
+<li class="indx">Cinders, <a href="#Page_171">171</a>.</li>
+
+<li class="indx">Clark’s Glasses, <a href="#Page_123">123</a>.</li>
+
+<li class="indx">Cliffs, <a href="#Page_164">164</a>.</li>
+
+<li class="indx">Clock, <a href="#Page_135">135</a>.</li>
+
+<li class="indx">Cloud-ocean, <a href="#Page_179">179</a>.</li>
+
+<li class="indx">Clouds:</li>
+<li class="isub1">cirrous, <a href="#Page_27">27</a>, <a href="#Page_28">28</a>;</li>
+<li class="isub1">beautiful, <a href="#Page_54">54</a>;</li>
+<li class="isub1">and rain, <a href="#Page_111">111</a>;</li>
+<li class="isub1">formed, <a href="#Page_249">249</a>.</li>
+
+<li class="indx">Coal-beds, <a href="#Page_115">115</a>.</li>
+
+<li class="indx">Coal:</li>
+<li class="isub1">energy, <a href="#Page_73">73–75</a>, <a href="#Page_111">111</a>;</li>
+<li class="isub1">destroyed, <a href="#Page_97">97</a>;</li>
+<li class="isub1">wasted, <a href="#Page_101">101</a>;</li>
+<li class="isub1">stock, <a href="#Page_112">112</a>.</li>
+
+<li class="indx">Cobweb, simile, <a href="#Page_26">26</a>.</li>
+
+<li class="indx">Cold:</li>
+<li class="isub1">and eclipses, <a href="#Page_40">40</a>;</li>
+<li class="isub1">in planets, <a href="#Page_136">136</a>.</li>
+
+<li class="indx">Colorado, <a href="#Page_50">50</a>.</li>
+
+<li class="indx"><a id="Colors"></a>Colors:</li>
+<li class="isub1">in eclipses (<abbr>q. v.</abbr>), <a href="#Page_65">65</a>;</li>
+<li class="isub1">mental, <a href="#Page_70">70</a>, <a href="#Page_71">71</a>;</li>
+<li class="isub1">in Jupiter (<abbr>q. v.</abbr>), <a href="#Page_127">127</a>;</li>
+<li class="isub1">in moon (<abbr>q. v.</abbr>), <a href="#Page_168">168</a>;</li>
+<li class="isub1">in stars (<abbr>q. v.</abbr>), <a href="#Page_227">227</a>;</li>
+<li class="isub1">spectrum (<abbr>q. v.</abbr>), <a href="#Page_236">236</a>.</li>
+
+<li class="indx">Comet-hunters, <a href="#Page_204">204</a>, <a href="#Page_207">207</a>.</li>
+
+<li class="indx"><a id="Comets"></a>Comets:</li>
+<li class="isub1">chapter, <a href="#Page_199">199–220</a>;</li>
+<li class="isub1">Donati’s, <a href="#Page_200">201</a>, <a href="#Page_204">204</a>, <a href="#Page_205">205</a>, <a href="#Page_207">207</a>, <a href="#Page_208">209</a>, <a href="#Page_216">217</a>;</li>
+<li class="isub1">one part, <a href="#Page_203">203</a>;</li>
+<li class="isub1">parts and name, <a href="#Page_208">208</a>;</li>
+<li class="isub1">tail (<abbr>q. v.</abbr>), <a href="#Page_208">208</a>, <a href="#Page_211">211</a>;</li>
+<li class="isub1">diameter and parts, <a href="#Page_216">216</a>;</li>
+<li class="isub1">spectroscope, elements, dread, <a href="#Page_219">219</a>;</li>
+<li class="isub1">numerous, stone, <a href="#Page_219">219</a>, <a href="#Page_220">220</a>;</li>
+<li class="isub1">kernel, <a href="#Page_220">220</a>;</li>
+<li class="isub1">(1858), <a href="#Page_213">213–216</a>;</li>
+<li class="isub1">(1866), <a href="#Page_200">200</a>.</li>
+
+<li class="indx">Common, A. A., <a href="#Page_238">239</a>, <a href="#Page_247">247</a>.</li>
+
+<li class="indx">Compass, <a href="#Page_86">86</a>.</li>
+
+<li class="indx">Connecticut Observations, <a href="#Page_186">186</a>, <a href="#Page_242">242</a>.</li>
+
+<li class="indx">Converter, <a href="#Page_104">104–108</a>.</li>
+
+<li class="indx">Coral, <a href="#Page_151">151</a>.</li>
+
+<li class="indx"><a id="Corn"></a>Corn, <a href="#Page_111">111</a>.</li>
+<li class="isub1">(See <i><a href="#Grain">Grain</a></i>.)</li>
+
+<li class="indx"><a id="Corona"></a>Corona, <a href="#Page_7">7</a>, <a href="#Page_36">36</a>, <a href="#Page_37">37</a>, <a href="#Page_40">40</a>, <a href="#Page_41">41</a>, <a href="#Page_43">43</a>, <a href="#Page_44">45–52</a>, <a href="#Page_55">55</a>, <a href="#Page_56">56</a>, <a href="#Page_59">59</a>, <a href="#Page_60">60–62</a>.</li>
+
+<li class="indx">Cotton-mill, <a href="#Page_74">74</a>.</li>
+
+<li class="indx">Counting, <a href="#Page_94">94</a>.</li>
+
+<li class="indx">Cracks, celestial, <a href="#Page_163">163</a>.</li>
+
+<li class="indx">Craters, <a href="#Page_164">164</a>.</li>
+<li class="isub1">(See special names.)</li>
+
+<li class="indx">Crystalline Structure, <a href="#Page_4">4</a>, <a href="#Page_23">23–27</a>.</li>
+
+<li class="indx">Cyclones, <a href="#Page_24">24</a>, <a href="#Page_31">31</a>, <a href="#Page_32">32</a>, <a href="#Page_68">68</a>.</li>
+
+<li class="ifrst">Decay, <a href="#Page_248">248</a>, <a href="#Page_249">249</a>.</li>
+
+<li class="indx">Delambre’s History, <a href="#Page_207">207</a>.</li>
+
+<li class="indx">De la Rue’s Engraving, <a href="#Page_124">125</a>.</li>
+
+<li class="indx">Delfthaven, <a href="#Page_5">5</a>.</li>
+
+<li class="indx">Denning’s Theory, <a href="#Page_197">197</a>.</li>
+
+<li class="indx">Diamonds, melted, <a href="#Page_103">103</a>.</li>
+
+<li class="indx">Dies Iræ, <a href="#Page_249">249</a>.</li>
+
+<li class="indx"><a id="Dipper"></a>Dipper, <a href="#Page_207">207</a>, <a href="#Page_208">208</a>.</li>
+<li class="isub1">(See <i><a href="#Great_Bear">Great Bear</a></i>, <i>Polar</i>.)</li>
+
+<li class="indx">Diurnal Oscillation, <a href="#Page_87">87</a>.</li>
+
+<li class="indx"><a id="Dog"></a>Dog, anecdote of, <a href="#Page_42">42</a>.</li>
+<li class="isub1">(See <i><a href="#Animals">Animals</a></i>.)</li>
+
+<li class="indx">Donati, <a href="#Page_200">201</a>, <a href="#Page_204">204</a>, <a href="#Page_205">205</a>, <a href="#Page_207">207</a>, <a href="#Page_208">209</a>, <a href="#Page_213">213</a>, <a href="#Page_216">217</a>.</li>
+<li class="isub1">(See <i><a href="#Comets">Comets</a></i>.)</li>
+
+<li class="indx">Double Stars, <a href="#Page_233">233</a>.</li>
+
+<li class="indx">Draper, Professor Henry, <a href="#Page_128">128</a>, <a href="#Page_246">246</a>, <a href="#Page_247">247</a>.</li>
+
+<li class="indx">Ducks, noise, <a href="#Page_188">188</a>.</li>
+
+<li class="indx">Dust, <a href="#Page_34">34</a>, <a href="#Page_100">100</a>, <a href="#Page_101">101</a>, <a href="#Page_102">102</a>, <a href="#Page_104">105</a>, <a href="#Page_197">197</a>.</li>
+
+<li class="indx">Dynamite, <a href="#Page_182">182</a>, <a href="#Page_185">185</a>, <a href="#Page_220">220</a>.</li>
+
+<li class="ifrst">Earth:</li>
+<li class="isub1">relations, <a href="#Page_3">3</a>, <a href="#Page_4">4</a>;</li>
+<li class="isub1">description difficult, <a href="#Page_6">6</a>;</li>
+<li class="isub1">temperature (<abbr>q. v.</abbr>), <a href="#Page_34">34</a>, <a href="#Page_101">101</a>;</li>
+<li class="isub1">a string of earths, <a href="#Page_96">96</a>;</li>
+<li class="isub1">stars like, <a href="#Page_118">118</a>;</li>
+<li class="isub1">seen from outside, <a href="#Page_133">133–135</a>;</li>
+<li class="isub1"><span class="pagenum" id="Page_255">255</span>craters, <a href="#Page_148">148</a>.</li>
+
+<li class="indx">Earthquakes, <a href="#Page_220">220</a>.</li>
+<li class="isub1">(See <i><a href="#Charleston_Earthquake">Charleston</a></i>.)</li>
+
+<li class="indx">Earth-shine, <a href="#Page_167">167</a>, <a href="#Page_172">172</a>.</li>
+
+<li class="indx">Eclipses:</li>
+<li class="isub1">total, <a href="#Page_7">7</a>, <a href="#Page_37">37</a>;</li>
+<li class="isub1">screen, <a href="#Page_36">36</a>;</li>
+<li class="isub1">three, <a href="#Page_39">39</a>, <a href="#Page_55">55</a>;</li>
+<li class="isub1">partial, <a href="#Page_40">40</a>;</li>
+<li class="isub1">singular gloom, <a href="#Page_39">39–43</a>;</li>
+<li class="isub1">causing fright, <a href="#Page_43">43</a>;</li>
+<li class="isub1">colors (<abbr>q. v.</abbr>), <a href="#Page_48">48</a>, <a href="#Page_56">56</a>, <a href="#Page_61">61</a>, <a href="#Page_65">65</a>, <a href="#Page_66">66</a>;</li>
+<li class="isub1">(1842), <a href="#Page_41">41</a>;</li>
+<li class="isub1">(1857), <a href="#Page_48">48</a>;</li>
+<li class="isub1">(1869), <a href="#Page_39">39</a>, <a href="#Page_40">40</a>;</li>
+<li class="isub1">(1870), <a href="#Page_44">44</a>, <a href="#Page_61">61</a>;</li>
+<li class="isub1">(1871), <a href="#Page_50">50</a>, <a href="#Page_66">66</a>, <a href="#Page_68">68</a>;</li>
+<li class="isub1">(1878), <a href="#Page_38">38</a>, <a href="#Page_50">50</a>, <a href="#Page_56">57</a>, <a href="#Page_59">58</a>.</li>
+<li class="isub1">(See <i><a href="#Total_Eclipse">Total</a></i>.)</li>
+
+<li class="indx"><a id="Egypt"></a>Egypt, <a href="#Page_116">116</a>, <a href="#Page_234">234</a>.</li>
+<li class="isub1">(See <i><a href="#Pyramids">Pyramids</a></i>.)</li>
+
+<li class="indx">Electricity, <a href="#Page_13">13</a>, <a href="#Page_75">75</a>, <a href="#Page_76">76</a>.</li>
+
+<li class="indx"><a id="Electric_Light"></a>Electric Light, <a href="#Page_7">7</a>.</li>
+
+<li class="indx"><a id="Electric_Spark"></a>Electric Spark, <a href="#Page_242">242</a>.</li>
+<li class="isub1">(See <i><a href="#Lightning">Lightning</a></i>.)</li>
+
+<li class="indx"><a id="Electric_Storm"></a>Electric Storm, <a href="#Page_84">84</a>, <a href="#Page_85">85</a>, <a href="#Page_88">88</a>.</li>
+
+<li class="indx">Elizabeth, Queen, <a href="#Page_115">115</a>.</li>
+
+<li class="indx">Engine-power, <a href="#Page_98">98</a>, <a href="#Page_111">111</a>.</li>
+
+<li class="indx"><a id="England"></a>England:</li>
+<li class="isub1">fleets, <a href="#Page_2">2</a>;</li>
+<li class="isub1">coal, <a href="#Page_115">115</a>.</li>
+<li class="isub1">(See <i><a href="#Britain_Ancient">Britain</a></i>, <i><a href="#London">London</a></i>.)</li>
+
+<li class="indx">Engraving, <a href="#Page_17">17</a>.</li>
+
+<li class="indx">Enigma, <a href="#Page_228">228</a>.</li>
+
+<li class="indx">Ephemera, <a href="#Page_250">250</a>, <a href="#Page_251">251</a>.</li>
+
+<li class="indx">Equatorial Landscape, <a href="#Page_13">13</a>, <a href="#Page_17">17</a>, <a href="#Page_18">18</a>, <a href="#Page_47">47</a>.</li>
+
+<li class="indx">Equatorial Telescope, <a href="#Page_122">122</a>.</li>
+
+<li class="indx">Ericsson:</li>
+<li class="isub1">engravings, <a href="#Page_112">112</a>, <a href="#Page_113">113</a>;</li>
+<li class="isub1">discoveries, <a href="#Page_163">163</a>.</li>
+
+<li class="indx">Eruptive Promontories, <a href="#Page_66">66–68</a>.</li>
+
+<li class="indx"><a id="Etna"></a>Etna, <a href="#Page_164">164</a>, <a href="#Page_181">181</a>.</li>
+
+<li class="indx">Europe, size, <a href="#Page_25">25</a>.</li>
+
+<li class="indx">Evolution, planetary, <a href="#Page_139">139</a>.</li>
+
+<li class="indx">Explosive Forces, <a href="#Page_182">182–194</a>.</li>
+
+<li class="indx"><a id="Eye"></a>Eye, <a href="#Page_71">71</a>, <a href="#Page_227">227</a>.</li>
+
+<li class="indx">Eye-pieces, <a href="#Page_47">47</a>, <a href="#Page_63">63</a>.</li>
+
+<li class="ifrst">Fabricius’s Observations, <a href="#Page_8">8</a>.</li>
+
+<li class="indx">Fact and Fancy, <a href="#Page_175">175</a>.</li>
+
+<li class="indx">Factory, <a href="#Page_73">73</a>.</li>
+
+<li class="indx">Faculæ, <a href="#Page_32">32</a>, <a href="#Page_33">33</a>.</li>
+
+<li class="indx"><a id="Falling"></a>Falling, <a href="#Page_242">242</a>, <a href="#Page_243">243</a>.</li>
+
+<li class="indx">Falling Stars, <a href="#Page_193">193</a>.</li>
+<li class="isub1">(See <i><a href="#Meteors">Meteors</a></i>, <i><a href="#Shooting-stars">Shooting</a></i>.)</li>
+
+<li class="indx">Faraday, Michael, <a href="#Page_76">76</a>.</li>
+
+<li class="indx">Fault, technical term, <a href="#Page_156">156</a>.</li>
+
+<li class="indx">Faust, <a href="#Page_139">139</a>.</li>
+
+<li class="indx">Faye:</li>
+<li class="isub1">theory, <a href="#Page_29">29–32</a>;</li>
+<li class="isub1">on Comets’ Tails, <a href="#Page_212">212</a>.</li>
+
+<li class="indx">Fern-like Forms, <a href="#Page_25">25</a>, <a href="#Page_26">26</a>.</li>
+
+<li class="indx">Filaments, <a href="#Page_25">25–27</a>, <a href="#Page_30">30</a>, <a href="#Page_55">55</a>, <a href="#Page_56">56</a>, <a href="#Page_65">65</a>, <a href="#Page_66">66</a>, <a href="#Page_68">68</a>.</li>
+
+<li class="indx">Fire, in sun (<abbr>q. v.</abbr>), <a href="#Page_92">92</a>.</li>
+<li class="isub1">(See <i><a href="#Flames">Flames</a></i>, <i><a href="#Heat">Heat</a></i>.)</li>
+
+<li class="indx">Fixed Stars, <a href="#Page_233">233</a>.</li>
+
+<li class="indx">Flame-like Appearances, <a href="#Page_23">23</a>, <a href="#Page_24">24</a>.</li>
+
+<li class="indx"><a id="Flames"></a>Flames, <a href="#Page_65">65</a>, <a href="#Page_66">66</a>, <a href="#Page_69">69</a>, <a href="#Page_185">185</a>.</li>
+
+<li class="indx">Flashes, <a href="#Page_188">189</a>, <a href="#Page_195">195</a>.</li>
+
+<li class="indx">Flax, <a href="#Page_111">111</a>.</li>
+
+<li class="indx"><a id="Flowers"></a>Flowers, color (<abbr>q. v.</abbr>), <a href="#Page_70">70</a>.</li>
+<li class="isub1">(See <i><a href="#Rose">Rose</a></i>, <i><a href="#Plants">Plants</a></i>.)</li>
+
+<li class="indx">Foliage-forms, <a href="#Page_32">32</a>.</li>
+
+<li class="indx">Fontenelle’s Story, <a href="#Page_133">133</a>.</li>
+
+<li class="indx">Forbes’s Observations, <a href="#Page_38">38</a>, <a href="#Page_39">39</a>.</li>
+
+<li class="indx">Frankenstein, <a href="#Page_221">221</a>.</li>
+
+<li class="indx">Franklin’s Discoveries, <a href="#Page_76">76</a>.</li>
+
+<li class="indx">Fraunhofer Studies, <a href="#Page_235">235</a>.</li>
+
+<li class="indx">French Institute, <a href="#Page_186">186</a>.</li>
+
+<li class="indx">Frost-crystals (<abbr>q. v.</abbr>), <a href="#Page_23">23</a>.</li>
+
+<li class="indx">Furnaces, <a href="#Page_101">101</a>.</li>
+
+<li class="ifrst">Galileo, <a href="#Page_8">8</a>, <a href="#Page_121">121–123</a>, <a href="#Page_139">139</a>, <a href="#Page_140">140</a>.</li>
+
+<li class="indx">Gas:</li>
+<li class="isub1">glowing, <a href="#Page_44">44</a>;</li>
+<li class="isub1">in sun, <a href="#Page_60">60</a>.</li>
+
+<li class="indx">Gas-jets, <a href="#Page_40">40</a>, <a href="#Page_61">61</a>, <a href="#Page_68">68</a>, <a href="#Page_88">88</a>.</li>
+
+<li class="indx">Gassendi’s View, <a href="#Page_172">172</a>, <a href="#Page_173">173</a>.</li>
+
+<li class="indx">Gelinck’s Observations, <a href="#Page_80">80</a>.</li>
+
+<li class="indx">Geminids, <a href="#Page_196">196</a>.</li>
+
+<li class="indx">Genii, <a href="#Page_193">193</a>.</li>
+
+<li class="indx">Geographers and Geologists, <a href="#Page_133">133</a>.</li>
+
+<li class="indx">Glare, <a href="#Page_14">14</a>, <a href="#Page_18">18</a>, <a href="#Page_62">62–64</a>.</li>
+
+<li class="indx">Glass:</li>
+<li class="isub1">spun, <a href="#Page_26">26</a>;</li>
+<li class="isub1">globe, <a href="#Page_144">145</a>.</li>
+
+<li class="indx">Glow-worms, <a href="#Page_7">7</a>, <a href="#Page_117">117</a>.</li>
+
+<li class="indx">Good Hope Observations, <a href="#Page_80">80</a>.</li>
+
+<li class="indx">Gould’s Researches, <a href="#Page_80">80</a>.</li>
+
+<li class="indx"><a id="Grain"></a>Grain, prices, <a href="#Page_77">77</a>, <a href="#Page_80">80</a>, <a href="#Page_87">87</a>.</li>
+<li class="isub1">(See <i><a href="#Corn">Corn</a></i>, <i><a href="#Sun-spots">Sun-spots</a></i>, <i><a href="#Wheat">Wheat</a></i>.)</li>
+
+<li class="indx">Gramarye, <a href="#Page_92">92</a>.</li>
+
+<li class="indx">Grass-blades, <a href="#Page_66">66</a>, <a href="#Page_72">72</a>.</li>
+
+<li class="indx">Grasses, <a href="#Page_26">26</a>.</li>
+
+<li class="indx">Gravitation, <a href="#Page_72">72</a>, <a href="#Page_203">203</a>;</li>
+<li class="isub1">negative, <a href="#Page_215">215</a>.</li>
+
+<li class="indx"><a id="Great_Bear"></a>Great Bear, <a href="#Page_207">207</a>.</li>
+<li class="isub1">(See <i><a href="#Dipper">Dipper</a></i>, <i><a href="#Polar_Star">Polar</a></i>.)</li>
+
+<li class="indx">Green’s Maps, <a href="#Page_130">130</a>.</li>
+
+<li class="indx">Greenwich Observatory, <a href="#Page_2">2</a>, <a href="#Page_81">81</a>, <a href="#Page_81">82</a>, <a href="#Page_84">84</a>, <a href="#Page_85">85</a>, <a href="#Page_88">88</a>, <a href="#Page_89">89</a>.</li>
+
+<li class="indx"><a id="Gulliver"></a>Gulliver’s Travels, <a href="#Page_131">131</a>, <a href="#Page_132">132</a>.</li>
+<li class="isub1">(See <i><a href="#Swift_Dean">Swift</a></i>.)</li>
+
+<li class="indx">Gunpowder, <a href="#Page_186">186</a>.</li>
+
+<li class="indx">Guns, <a href="#Page_135">135</a>.</li>
+<li class="isub1">(See <i><a href="#Cannon-ball">Cannon-ball</a></i>.)</li>
+
+<li class="ifrst">Hall Island, <a href="#Page_130">130</a>.</li>
+
+<li class="indx">Hall, Professor, <a href="#Page_131">131</a>.</li>
+
+<li class="indx">Hand, illustration, <a href="#Page_168">168</a>.</li>
+
+<li class="indx">Harkness’s Observations, <a href="#Page_44">44</a>.</li>
+
+<li class="indx">Harvests, <a href="#Page_90">90</a>.</li>
+
+<li class="indx">Hastings, Professor, <a href="#Page_60">60</a>.</li>
+
+<li class="indx"><a id="Heat"></a>Heat:</li>
+<li class="isub1">development, <a href="#Page_13">13</a>;</li>
+<li class="isub1">concentration, <a href="#Page_19">19</a>;</li>
+<li class="isub1">loss, <a href="#Page_29">29</a>;</li>
+<li class="isub1">confinement, <a href="#Page_33">33</a>;</li>
+<li class="isub1">sensation, <a href="#Page_71">71</a>;</li>
+<li class="isub1">vibrations, <a href="#Page_72">72</a>;</li>
+<li class="isub1">energy, <a href="#Page_91">91</a>;</li>
+<li class="isub1">amount, <a href="#Page_92">92</a>, <a href="#Page_97">97</a>;</li>
+<li class="isub1">computation, <a href="#Page_94">94–96</a>;</li>
+<li class="isub1">diminution, <a href="#Page_101">101</a>;</li>
+<li class="isub1">emission, <a href="#Page_102">102</a>;</li>
+<li class="isub1">storage, <a href="#Page_111">111</a>;</li>
+<li class="isub1">in sugar, <a href="#Page_188">188</a>.</li>
+<li class="isub1">(See <i>Flames</i>, <i><a href="#Sun">Sun</a></i>.)<span class="pagenum" id="Page_256">256</span></li>
+
+<li class="indx">Hecla, <a href="#Page_164">164</a>, <a href="#Page_181">181</a>.</li>
+
+<li class="indx">Hedgehog-spines, simile, <a href="#Page_68">68</a>.</li>
+
+<li class="indx">Helmholtz’s Estimates, <a href="#Page_98">98</a>.</li>
+
+<li class="indx">Hengist and Horsa, <a href="#Page_1">1</a>.</li>
+<li class="isub1">(See <i><a href="#Britain_Ancient">Britain</a></i>.)</li>
+
+<li class="indx">Hercules, <a href="#Page_238">238</a>.</li>
+
+<li class="indx">Herschel, Sir John:</li>
+<li class="isub1">sun-spots, <a href="#Page_12">12–14</a>;</li>
+<li class="isub1">electric storms, <a href="#Page_88">88</a>;</li>
+<li class="isub1">comet’s tail, <a href="#Page_216">216</a>.</li>
+
+<li class="indx">Herschel, Sir William:</li>
+<li class="isub1">avoidance of light, <a href="#Page_18">18</a>;</li>
+<li class="isub1">prices, <a href="#Page_79">79</a>;</li>
+<li class="isub1">sun-spots (<abbr>q. v.</abbr>), <a href="#Page_129">129</a>.</li>
+
+<li class="indx">Herschel’s Outlines, <a href="#Page_11">11</a>.</li>
+
+<li class="indx">Holden, Professor, <a href="#Page_124">124</a>.</li>
+
+<li class="indx">Honeycomb Structure, <a href="#Page_30">30</a>.</li>
+
+<li class="indx">Huggins’s Experiment, <a href="#Page_234">234</a>, <a href="#Page_235">235</a>.</li>
+
+<li class="indx"><a id="Humanity"></a>Humanity, deified, <a href="#Page_172">172</a>.</li>
+
+<li class="indx">Human Race, <a href="#Page_250">250</a>.</li>
+
+<li class="indx">Humboldt, <a href="#Page_195">195</a>.</li>
+
+<li class="indx">Humming-bird, <a href="#Page_70">70</a>.</li>
+
+<li class="indx">Hunt, Professor, <a href="#Page_136">136</a>, <a href="#Page_219">219</a>.</li>
+
+<li class="indx">Hydrogen, <a href="#Page_68">68</a>, <a href="#Page_99">99</a>, <a href="#Page_237">237</a>.</li>
+
+<li class="ifrst">Ibrahim, King, story, <a href="#Page_194">194</a>, <a href="#Page_195">195</a>.</li>
+
+<li class="indx">Ice:</li>
+<li class="isub1">melted, <a href="#Page_95">95</a>, <a href="#Page_96">96</a>;</li>
+<li class="isub1">never melted, <a href="#Page_163">163</a>, <a href="#Page_164">164</a>.</li>
+
+<li class="indx">Imbrian Sea, <a href="#Page_151">151</a>.</li>
+
+<li class="indx"><a id="Insects"></a>Insects, <a href="#Page_224">224</a>, <a href="#Page_250">250</a>.</li>
+<li class="isub1">(See <i><a href="#Ants">Ants</a></i>, <i><a href="#Bees">Bees</a></i>.)</li>
+
+<li class="indx"><a id="Iron"></a>Iron:</li>
+<li class="isub1">melting, <a href="#Page_19">19</a>, <a href="#Page_107">107</a>;</li>
+<li class="isub1">appearance of cold, <a href="#Page_25">25</a>;</li>
+<li class="isub1">in sun, <a href="#Page_28">28</a>;</li>
+<li class="isub1">in man, <a href="#Page_221">221</a>;</li>
+<li class="isub1">in stars, <a href="#Page_236">236</a>, <a href="#Page_237">237</a>.</li>
+<li class="isub1">(See <i><a href="#Steel">Steel</a></i>.)</li>
+
+<li class="indx">Ironstone, <a href="#Page_188">188</a>.</li>
+
+<li class="indx">Ivy, <a href="#Page_115">115</a>.</li>
+
+<li class="ifrst">Janssen’s Observations, <a href="#Page_61">61</a>.</li>
+
+<li class="indx">Jevons, Professor, <a href="#Page_80">80</a>.</li>
+
+<li class="indx">Joseph in Egypt, <a href="#Page_90">90</a>.</li>
+
+<li class="indx">Jumping, <a href="#Page_241">241</a>, <a href="#Page_242">242</a>.</li>
+
+<li class="indx"><a id="Jupiter"></a>Jupiter, <a href="#Page_79">79</a>, <a href="#Page_118">118</a>, <a href="#Page_124">124</a>, <a href="#Page_127">127–129</a>, <a href="#Page_156">156</a>, <a href="#Page_185">185</a>, <a href="#Page_229">229</a>.</li>
+
+<li class="ifrst">Kensington Museum, <a href="#Page_221">221</a>.</li>
+
+<li class="indx">Kepler, on Comets, <a href="#Page_219">219</a>.</li>
+
+<li class="indx">Kernels, <a href="#Page_220">220</a>.</li>
+
+<li class="indx">Kew, <a href="#Page_88">88</a>.</li>
+
+<li class="indx">Kirchoff’s Researches, <a href="#Page_12">12</a>.</li>
+
+<li class="indx">Krakatao, <a href="#Page_181">181</a>, <a href="#Page_185">185</a>, <a href="#Page_186">186</a>.</li>
+
+<li class="ifrst">La Harpe, quoted, <a href="#Page_207">207</a>.</li>
+
+<li class="indx">Landscape, <a href="#Page_169">169</a>.</li>
+
+<li class="indx"><a id="Langley"></a>Langley, Prof. S. P.:</li>
+<li class="isub1">drawings, <a href="#Page_14">15</a>, <a href="#Page_17">16</a>, <a href="#Page_18">18</a>, <a href="#Page_19">19</a>, <a href="#Page_20">21</a>, <a href="#Page_23">22</a>, <a href="#Page_25">25</a>, <a href="#Page_28">28</a>, <a href="#Page_30">30</a>;</li>
+<li class="isub1">note-book, <a href="#Page_24">24</a>;</li>
+<li class="isub1">expedition, <a href="#Page_180">180</a>;</li>
+<li class="isub1">study of Reflection, <a href="#Page_216">216</a>.</li>
+<li class="isub1">(See <i><a href="#Allegheny">Allegheny</a></i>, <i><a href="#Pittsburg">Pittsburg</a></i>.)</li>
+
+<li class="indx">Latent Power, <a href="#Page_220">220</a>.</li>
+
+<li class="indx">Laws of Nature, <a href="#Page_250">250</a>, <a href="#Page_251">251</a>.</li>
+
+<li class="indx"><a id="Leaf"></a>Leaf-like Appearances, <a href="#Page_23">23</a>.</li>
+<li class="isub1">(See <i><a href="#Willow-leaves">Willow</a></i>.)</li>
+
+<li class="indx">Lenses, <a href="#Page_102">102</a>, <a href="#Page_103">103</a>;</li>
+<li class="isub1">Galileo’s, <a href="#Page_123">123</a>.</li>
+
+<li class="indx">Leo, <a href="#Page_195">195</a>, <a href="#Page_197">197</a>.</li>
+
+<li class="indx">Liais’s Drawing, <a href="#Page_48">48</a>, <a href="#Page_50">50</a>.</li>
+
+<li class="indx">Lick Glass, <a href="#Page_123">123</a>.</li>
+
+<li class="indx"><a id="Light"></a>Light:</li>
+<li class="isub1">development, <a href="#Page_13">13</a>;</li>
+<li class="isub1">day and night, <a href="#Page_35">35</a>;</li>
+<li class="isub1">white (<abbr>q. v.</abbr>), <a href="#Page_48">48</a>;</li>
+<li class="isub1">mental (see <i><a href="#Eye">Eye</a></i>), <a href="#Page_71">71</a>;</li>
+<li class="isub1">from balloon, <a href="#Page_179">179</a>;</li>
+<li class="isub1">transmitted, <a href="#Page_227">227</a>.</li>
+<li class="isub1">(See <i><a href="#Sun">Sun</a></i>.)</li>
+
+<li class="indx"><a id="Lightning"></a>Lightning, <a href="#Page_75">75</a>, <a href="#Page_76">76</a>, <a href="#Page_242">242</a>, <a href="#Page_244">244</a>, <a href="#Page_245">245</a>.</li>
+<li class="isub1">(See <i><a href="#Electric_Storm">Electric</a></i>.)</li>
+
+<li class="indx">Lily, <a href="#Page_73">73</a>.</li>
+<li class="isub1">(See <i><a href="#Flowers">Flowers</a></i>.)</li>
+
+<li class="indx">Limited Express Train, <a href="#Page_5">5</a>.</li>
+
+<li class="indx">Loaf-sugar, experiment, <a href="#Page_188">188</a>.</li>
+
+<li class="indx">Lockyer’s Land, <a href="#Page_130">130</a>.</li>
+
+<li class="indx">Lockyer’s Solar Physics, <a href="#Page_59">59</a>, <a href="#Page_61">61</a>, <a href="#Page_236">236</a>, <a href="#Page_238">238</a>.</li>
+
+<li class="indx">Lombardy, <a href="#Page_151">151</a>.</li>
+
+<li class="indx"><a id="London"></a>London, <a href="#Page_111">111</a>.</li>
+
+<li class="indx"><a id="Lost_Pleiad"></a>Lost Pleiad (<abbr>q. v.</abbr>), <a href="#Page_207">207</a>.</li>
+
+<li class="indx">Louis XV., <a href="#Page_42">42</a>.</li>
+
+<li class="indx">Louis XVI., <a href="#Page_221">221</a>.</li>
+
+<li class="indx"><a id="Lunar_Alps"></a>Lunar Alps (<i>q. v.</i>), <a href="#Page_148">148</a>, <a href="#Page_148">149</a>.</li>
+<li class="isub1">(See <i><a href="#Moon">Moon</a></i>.)</li>
+
+<li class="indx"><a id="Lunar_Apennines"></a>Lunar Apennines (<abbr>q. v.</abbr>), <a href="#Page_152">153</a>.</li>
+
+<li class="indx"><a id="Lunar_Shadows"></a>Lunar Shadows, <a href="#Page_36">36</a>, <a href="#Page_37">37</a>, <a href="#Page_39">39</a>, <a href="#Page_56">56</a>.</li>
+
+<li class="indx">Lyrids, <a href="#Page_196">196</a>, <a href="#Page_200">200</a>.</li>
+
+<li class="ifrst">Macartney’s Lens, <a href="#Page_103">103</a>.</li>
+
+<li class="indx">Maelstrom, <a href="#Page_27">27</a>.</li>
+
+<li class="indx">Magic Lantern, simile, <a href="#Page_220">220</a>.</li>
+
+<li class="indx">Magnesium, <a href="#Page_236">236</a>, <a href="#Page_237">237</a>.</li>
+
+<li class="indx">Magnetic Needle, <a href="#Page_81">81</a>, <a href="#Page_81">82</a>, <a href="#Page_84">84</a>, <a href="#Page_85">85</a>, <a href="#Page_87">87</a>, <a href="#Page_89">89</a>.</li>
+
+<li class="indx">Mammoth Cave, <a href="#Page_40">40</a>.</li>
+
+<li class="indx">Man, chemistry of, <a href="#Page_221">221</a>, <a href="#Page_233">233</a>.</li>
+<li class="isub1">(See <i><a href="#Humanity">Humanity</a></i>.)</li>
+
+<li class="indx">Manhattan Island, <a href="#Page_111">111</a>.</li>
+
+<li class="indx">Mare Crisium, <a href="#Page_143">143</a>.</li>
+
+<li class="indx">Mare Serenitatis, <a href="#Page_143">143</a>, <a href="#Page_144">144</a>.</li>
+
+<li class="indx"><a id="Mars"></a>Mars, <a href="#Page_118">118</a>, <a href="#Page_128">128–132</a>, <a href="#Page_148">148</a>.</li>
+
+<li class="indx">Mason’s Publication, <a href="#Page_136">137</a>.</li>
+
+<li class="indx">Matterhorn, <a href="#Page_148">148</a>, <a href="#Page_167">167</a>.</li>
+
+<li class="indx">Mayflower, <a href="#Page_5">5</a>.</li>
+
+<li class="indx">Meadows, <a href="#Page_172">172</a>.</li>
+
+<li class="indx">Mecca, <a href="#Page_175">175</a>.</li>
+
+<li class="indx">Medusa, <a href="#Page_228">228</a>.</li>
+
+<li class="indx">Memnon, <a href="#Page_234">234</a>.</li>
+
+<li class="indx">Mercator, <a href="#Page_163">163</a>, <a href="#Page_164">165</a>.<span class="pagenum" id="Page_257">257</span></li>
+
+<li class="indx"><a id="Mercury"></a>Mercury, <a href="#Page_3">3</a>, <a href="#Page_118">118</a>, <a href="#Page_136">136</a>, <a href="#Page_229">229</a>.</li>
+
+<li class="indx">Messier, anecdote, <a href="#Page_207">207</a>.</li>
+
+<li class="indx">Metals, melted, <a href="#Page_103">103</a>.</li>
+<li class="isub1">(See <i><a href="#Iron">Iron</a></i>.)</li>
+
+<li class="indx">Metaphysics, <a href="#Page_70">70</a>, <a href="#Page_71">71</a>.</li>
+
+<li class="indx"><a id="Meteorites"></a>Meteorites:</li>
+<li class="isub1">around Saturn, <a href="#Page_124">124</a>;</li>
+<li class="isub1">recent, <a href="#Page_187">187</a>;</li>
+<li class="isub1">lawsuit, <a href="#Page_187">187</a>, <a href="#Page_188">188</a>;</li>
+<li class="isub1">analyzed, <a href="#Page_191">191</a>, <a href="#Page_192">192</a>;</li>
+<li class="isub1">in Iowa, <a href="#Page_199">199</a>, <a href="#Page_200">200</a>;</li>
+<li class="isub1">swarm, <a href="#Page_200">200</a>;</li>
+<li class="isub1">cracking, <a href="#Page_211">211</a>.</li>
+
+<li class="indx"><a id="Meteors"></a>Meteors, <a href="#Page_98">98</a>, <a href="#Page_175">175–198</a>;</li>
+<li class="isub1">(1868), <a href="#Page_188">189</a>.</li>
+<li class="isub1">(See <i><a href="#Falling">Falling</a></i>, <i><a href="#Shooting-stars">Shooting</a></i>.)</li>
+
+<li class="indx">Meunier’s Investigations, <a href="#Page_192">192</a>.</li>
+
+<li class="indx">Mexican Gulf, <a href="#Page_38">38</a>.</li>
+
+<li class="indx">Microcosm, <a href="#Page_222">222</a>.</li>
+
+<li class="indx">Micromegas, <a href="#Page_223">223</a>.</li>
+
+<li class="indx">Microscope, <a href="#Page_224">224</a>.</li>
+
+<li class="indx">Middle Ages, <a href="#Page_91">91</a>, <a href="#Page_175">175</a>.</li>
+
+<li class="indx">Milky Way, <a href="#Page_224">224</a>, <a href="#Page_224">225</a>.</li>
+
+<li class="indx">Milton, quoted, <a href="#Page_14">14</a>, <a href="#Page_38">38</a>.</li>
+
+<li class="indx">Mind-causation, <a href="#Page_70">70</a>, <a href="#Page_71">71</a>.</li>
+
+<li class="indx">Mirror, <a href="#Page_102">102</a>, <a href="#Page_107">107</a>.</li>
+
+<li class="indx">Mississippi, <a href="#Page_134">134</a>.</li>
+
+<li class="indx">Mites, <a href="#Page_224">224</a>.</li>
+
+<li class="indx">Mizar, <a href="#Page_207">207</a>.</li>
+
+<li class="indx">M’Leod’s Drawing, <a href="#Page_44">44</a>.</li>
+
+<li class="indx">Monochromatic Light (<abbr>q. v.</abbr>), <a href="#Page_63">63</a>.</li>
+
+<li class="indx">Montaigne of Limoges, <a href="#Page_207">207</a>.</li>
+
+<li class="indx">Mont Blanc, <a href="#Page_156">156</a>.</li>
+
+<li class="indx">Monte Rosa, <a href="#Page_167">167</a>.</li>
+
+<li class="indx"><a id="Moon"></a>Moon:</li>
+<li class="isub1">practical observations, <a href="#Page_2">2</a>;</li>
+<li class="isub1">newly studied, <a href="#Page_3">3</a>;</li>
+<li class="isub1">distance, <a href="#Page_4">4–6</a>;</li>
+<li class="isub1">size, <a href="#Page_5">5</a>, <a href="#Page_6">6</a>, <a href="#Page_140">140</a>, <a href="#Page_156">156</a>;</li>
+<li class="isub1">shadows (<abbr>q. v.</abbr>), <a href="#Page_36">36</a>, <a href="#Page_124">125</a>;</li>
+<li class="isub1">in sun-eclipse, <a href="#Page_41">41</a>;</li>
+<li class="isub1">planetary relations, <a href="#Page_117">117–174</a>;</li>
+<li class="isub1">and Jupiter, <a href="#Page_127">127</a>;</li>
+<li class="isub1">photograph, <a href="#Page_136">137</a>;</li>
+<li class="isub1">full, <a href="#Page_141">141</a>, <a href="#Page_144">144</a>, <a href="#Page_147">147</a>;</li>
+<li class="isub1">Man in the, <a href="#Page_143">143</a>;</li>
+<li class="isub1">mountains, <a href="#Page_144">144</a>;</li>
+<li class="isub1">craters, <a href="#Page_147">147</a>, <a href="#Page_148">148</a>;</li>
+<li class="isub1">temperature, <a href="#Page_159">159</a>;</li>
+<li class="isub1">airless, <a href="#Page_160">160</a>;</li>
+<li class="isub1">landscape (<abbr>q. v.</abbr>), <a href="#Page_169">169</a>;</li>
+<li class="isub1">age, <a href="#Page_171">171</a>;</li>
+<li class="isub1">broken up, <a href="#Page_192">192</a>;</li>
+<li class="isub1">like comet, <a href="#Page_215">215</a>.</li>
+<li class="isub1">(See <i><a href="#Lunar_Alps">Lunar</a></i>.)</li>
+
+<li class="indx"><a id="Moslem"></a>Moslem Traditions, <a href="#Page_175">175</a>, <a href="#Page_194">194</a>.</li>
+<li class="isub1">(See <i><a href="#Arab_Traditions">Arab</a></i>.)</li>
+
+<li class="indx">Moss, <a href="#Page_160">160</a>.</li>
+
+<li class="indx">Mouchot’s Engravings, <a href="#Page_109">109</a>, <a href="#Page_112">112</a>.</li>
+
+<li class="indx">Mountain Sickness, <a href="#Page_50">50</a>, <a href="#Page_53">53</a>.</li>
+
+<li class="ifrst"><a id="Naples"></a>Naples, <a href="#Page_155">155</a>, <a href="#Page_156">157</a>.</li>
+<li class="isub1">(See <i><a href="#Vesuvius">Vesuvius</a></i>.)</li>
+
+<li class="indx">Napoleon, <a href="#Page_80">80</a>, <a href="#Page_134">134</a>.</li>
+
+<li class="indx">Nasmyth’s Researches, <a href="#Page_11">11</a>, <a href="#Page_12">12</a>, <a href="#Page_14">14</a>, <a href="#Page_24">24</a>, <a href="#Page_25">25</a>, <a href="#Page_140">140</a>.</li>
+
+<li class="indx">Nativity of Jesus, <a href="#Page_229">229</a>.</li>
+
+<li class="indx">Nature’s Laws (<abbr>q. v.</abbr>), <a href="#Page_176">176</a>.</li>
+
+<li class="indx">Nebulæ, <a href="#Page_247">247</a>.</li>
+
+<li class="indx">Needle, <a href="#Page_228">228</a>.</li>
+<li class="isub1">(See <i><a href="#Cambric_Needle">Cambric</a></i>.)</li>
+
+<li class="indx">Neptune, <a href="#Page_121">121</a>.</li>
+
+<li class="indx">Nerves, none in camera, <a href="#Page_47">47</a>.</li>
+
+<li class="indx">Nerve Transmission, <a href="#Page_5">5</a>, <a href="#Page_6">6</a>.</li>
+
+<li class="indx"><a id="New_Astronomy"></a>New Astronomy, <a href="#Page_4">4</a>, <a href="#Page_75">75</a>, <a href="#Page_76">76</a>, <a href="#Page_117">117</a>, <a href="#Page_121">121</a>, <a href="#Page_171">171</a>, <a href="#Page_193">193</a>, <a href="#Page_222">222</a>, <a href="#Page_224">224</a>, <a href="#Page_227">227</a>, <a href="#Page_235">235</a>, <a href="#Page_246">246</a>, <a href="#Page_248">248</a>.</li>
+<li class="isub1">(See <i><a href="#Old_Astronomy">Old</a></i>.)</li>
+
+<li class="indx">Newcomb, Professor, <a href="#Page_55">55</a>.</li>
+
+<li class="indx">Newspapers, printed by the sun, <a href="#Page_74">74</a>.</li>
+
+<li class="indx">Newton, Professor, <a href="#Page_191">191</a>, <a href="#Page_195">195–197</a>.</li>
+
+<li class="indx">Newton, Sir Isaac, <a href="#Page_136">136</a>, <a href="#Page_203">203</a>, <a href="#Page_211">211</a>;</li>
+<li class="isub1">on Comets, <a href="#Page_215">215</a>, <a href="#Page_219">219</a>.</li>
+
+<li class="indx">Nightmare, <a href="#Page_67">67</a>.</li>
+
+<li class="indx">Northern Crown, <a href="#Page_208">208</a>, <a href="#Page_211">211</a>, <a href="#Page_230">230</a>.</li>
+
+<li class="indx">Novelists, theme for, <a href="#Page_193">193</a>, <a href="#Page_228">228</a>.</li>
+
+<li class="indx">Nucleus, <a href="#Page_11">11</a>, <a href="#Page_19">19</a>, <a href="#Page_216">216</a>.</li>
+<li class="isub1">(See <i><a href="#Comets">Comets</a></i>, <i><a href="#Corona">Corona</a></i>.)</li>
+
+<li class="ifrst">Oceans, <a href="#Page_179">179</a>.</li>
+
+<li class="indx"><a id="Old_Astronomy"></a>Old Astronomy, <a href="#Page_199">199</a>, <a href="#Page_203">203</a>, <a href="#Page_233">233</a>.</li>
+<li class="isub1">(See <i><a href="#New_Astronomy">New</a></i>.)</li>
+
+<li class="indx">Organisms in sun (<abbr>q. v.</abbr>), <a href="#Page_13">13</a>.</li>
+
+<li class="indx">Orion, <a href="#Page_238">238</a>, <a href="#Page_238">239</a>, <a href="#Page_247">247</a>.</li>
+
+<li class="indx">Oxygen, <a href="#Page_73">73</a>.</li>
+
+<li class="ifrst">Pacific Ocean, <a href="#Page_180">180</a>.</li>
+
+<li class="indx">Palinurus, <a href="#Page_243">243</a>.</li>
+
+<li class="indx">Parable, <a href="#Page_224">224</a>.</li>
+
+<li class="indx">Paris:</li>
+<li class="isub1">Observatory, <a href="#Page_42">42</a>, <a href="#Page_233">233</a>, <a href="#Page_247">247</a>;</li>
+<li class="isub1">Exposition, <a href="#Page_112">112</a>.</li>
+
+<li class="indx">Parker’s Lens, <a href="#Page_103">103</a>.</li>
+
+<li class="indx">Peirce, Professor, <a href="#Page_44">44</a>.</li>
+
+<li class="indx">Pennsylvania Coal, <a href="#Page_97">97</a>.</li>
+
+<li class="indx">Penumbra, <a href="#Page_11">11</a>, <a href="#Page_19">19</a>, <a href="#Page_20">20</a>.</li>
+
+<li class="indx">Perpignan, France, <a href="#Page_42">42</a>.</li>
+
+<li class="indx">Perseus, <a href="#Page_196">196</a>.</li>
+
+<li class="indx">Persian Rugs, <a href="#Page_70">70</a>.</li>
+
+<li class="indx">Philadelphia, <a href="#Page_88">88</a>.</li>
+
+<li class="indx">Philosopher’s Stone, <a href="#Page_92">92</a>.</li>
+
+<li class="indx">Phœbus, <a href="#Page_34">34</a>.</li>
+
+<li class="indx">Phosphorus, <a href="#Page_221">221</a>.</li>
+
+<li class="indx">Photographic Plate, <a href="#Page_71">71</a>.</li>
+
+<li class="indx">Photography, <a href="#Page_9">9</a>, <a href="#Page_19">19</a>, <a href="#Page_128">128</a>, <a href="#Page_236">236</a>, <a href="#Page_237">237</a>, <a href="#Page_241">241</a>, <a href="#Page_244">244</a>, <a href="#Page_247">247</a>, <a href="#Page_248">248</a>;</li>
+<li class="isub1">rapid, <a href="#Page_242">242</a>.</li>
+
+<li class="indx">Photometer, <a href="#Page_56">56</a>, <a href="#Page_108">108</a>.</li>
+
+<li class="indx">Photometry, <a href="#Page_230">230</a>.</li>
+
+<li class="indx">Photosphere, <a href="#Page_7">7</a>, <a href="#Page_17">17</a>, <a href="#Page_64">64</a>.</li>
+
+<li class="indx">Pickering, Professor, <a href="#Page_132">132</a>, <a href="#Page_227">227</a>, <a href="#Page_228">228</a>, <a href="#Page_246">246</a>.</li>
+
+<li class="indx">Pico Summit, <a href="#Page_148">148</a>.</li>
+
+<li class="indx">Piffard, Dr. H. G., <a href="#Page_245">245</a>.</li>
+
+<li class="indx">Pike’s Peak, <a href="#Page_50">50</a>, <a href="#Page_53">53–57</a>, <a href="#Page_60">60</a>.</li>
+
+<li class="indx">Pilgrim Fathers, <a href="#Page_5">5</a>.</li>
+
+<li class="indx"><span class="pagenum" id="Page_258">258</span>Pine-boughs, <a href="#Page_25">25</a>.</li>
+
+<li class="indx">Pine-trees, <a href="#Page_60">60</a>, <a href="#Page_72">72</a>.</li>
+
+<li class="indx"><a id="Pittsburg"></a>Pittsburg Observations, <a href="#Page_18">18</a>, <a href="#Page_19">19</a>.</li>
+<li class="isub1">(See <i><a href="#Allegheny">Allegheny</a></i>, <i><a href="#Langley">Langley</a></i>.)</li>
+
+<li class="indx">Planetoids, <a href="#Page_196">196</a>, <a href="#Page_197">197</a>, <a href="#Page_229">229</a>.</li>
+
+<li class="indx"><a id="Planets"></a>Planets:</li>
+<li class="isub1">condition, <a href="#Page_97">97</a>;</li>
+<li class="isub1">pulverized, <a href="#Page_100">100</a>;</li>
+<li class="isub1">and moon, <a href="#Page_117">117–174</a>;</li>
+<li class="isub1">isolated, <a href="#Page_176">176</a>.</li>
+<li class="isub1">(See <i><a href="#Jupiter">Jupiter</a></i>, <i><a href="#Mars">Mars</a></i>, <i><a href="#Mercury">Mercury</a></i>, <i><a href="#Saturn">Saturn</a></i>, <i><a href="#Sirius">Sirius</a></i>, <i><a href="#Stars">Stars</a></i>.)</li>
+
+<li class="indx"><a id="Plants"></a>Plants, <a href="#Page_72">72</a>, <a href="#Page_73">73</a>.</li>
+<li class="isub1">(See <i><a href="#Flowers">Flowers</a></i>.)</li>
+
+<li class="indx">Plato Crater, <a href="#Page_147">147</a>, <a href="#Page_148">148</a>, <a href="#Page_151">151</a>, <a href="#Page_152">152</a>.</li>
+
+<li class="indx">Pleiades, <a href="#Page_17">17</a>, <a href="#Page_230">231</a>, <a href="#Page_245">245</a>.</li>
+<li class="isub1">(See <i><a href="#Lost_Pleiad">Lost</a></i>.)</li>
+
+<li class="indx"><a id="Plume"></a>Plume, The, <a href="#Page_19">19</a>, <a href="#Page_23">23</a>, <a href="#Page_24">24</a>, <a href="#Page_55">55</a>.</li>
+
+<li class="indx">Pointers, <a href="#Page_208">208</a>.</li>
+<li class="isub1">(See <i><a href="#Dipper">Dipper</a></i>.)</li>
+
+<li class="indx">Poison, <a href="#Page_222">222</a>.</li>
+
+<li class="indx">Polariscope, <a href="#Page_49">49</a>.</li>
+
+<li class="indx">Polarization, <a href="#Page_18">18</a>.</li>
+
+<li class="indx">Polarizing Eye-piece, <a href="#Page_14">14</a>, <a href="#Page_18">18</a>.</li>
+
+<li class="indx"><a id="Polar_Star"></a>Polar Star, <a href="#Page_230">230</a>.</li>
+<li class="isub1">(See <i><a href="#Great_Bear">Great Bear</a></i>.)</li>
+
+<li class="indx">Polyp, <a href="#Page_152">152</a>.</li>
+
+<li class="indx">Pores, <a href="#Page_24">24</a>.</li>
+
+<li class="indx">Pouillet’s Invention, <a href="#Page_93">93</a>.</li>
+
+<li class="indx">Printing, indebtedness to the sun, <a href="#Page_74">74</a>.</li>
+
+<li class="indx">Prism, <a href="#Page_63">63</a>, <a href="#Page_64">64</a>.</li>
+<li class="isub1">(See <i><a href="#Colors">Colors</a></i>, <i><a href="#Scarlet">Scarlet</a></i>.)</li>
+
+<li class="indx">Proctor’s Observations, <a href="#Page_14">14</a>, <a href="#Page_59">59</a>, <a href="#Page_69">69</a>, <a href="#Page_87">87</a>.</li>
+
+<li class="indx">Prospero’s Wand, <a href="#Page_221">221</a>.</li>
+
+<li class="indx">Ptolemy, <a href="#Page_155">155</a>, <a href="#Page_160">161</a>.</li>
+
+<li class="indx"><a id="Pyramids"></a>Pyramids, <a href="#Page_99">99</a>, <a href="#Page_117">117</a>, <a href="#Page_233">233</a>, <a href="#Page_234">234</a>.</li>
+<li class="isub1">(See <i><a href="#Egypt">Egypt</a></i>.)</li>
+
+<li class="indx">Pyrheliometer, <a href="#Page_93">93</a>.</li>
+
+<li class="ifrst">Race, simile, <a href="#Page_179">179</a>.</li>
+
+<li class="indx">Radiant Energy, <a href="#Page_71">71</a>, <a href="#Page_74">74</a>;</li>
+<li class="isub1">rate, <a href="#Page_104">104</a>.</li>
+
+<li class="indx">Radiation, <a href="#Page_101">101</a>, <a href="#Page_108">108</a>.</li>
+
+<li class="indx">Railway Explosion, <a href="#Page_182">182</a>, <a href="#Page_182">183</a>.</li>
+
+<li class="indx">Railway, The, <a href="#Page_156">156</a>.</li>
+
+<li class="indx">Rain, <a href="#Page_111">111</a>.</li>
+
+<li class="indx">Rainbow, <a href="#Page_70">70</a>.</li>
+
+<li class="indx">Ranyard’s Photographs, <a href="#Page_50">50</a>.</li>
+
+<li class="indx">Red Sea, <a href="#Page_116">116</a>.</li>
+
+<li class="indx">Reflection, <a href="#Page_216">216</a>.</li>
+
+<li class="indx">Repulsive Force, <a href="#Page_215">215</a>.</li>
+
+<li class="indx">Ribbons, <a href="#Page_70">70</a>, <a href="#Page_236">236</a>.</li>
+
+<li class="indx">Rifts, <a href="#Page_163">163</a>, <a href="#Page_164">164</a>.</li>
+
+<li class="indx">Rings, <a href="#Page_123">123</a>, <a href="#Page_124">124</a>, <a href="#Page_152">152</a>, <a href="#Page_155">155</a>.</li>
+<li class="isub1">(See <i><a href="#Saturn">Saturn</a></i>.)</li>
+
+<li class="indx">Rockets, <a href="#Page_67">67</a>, <a href="#Page_68">68</a>.</li>
+
+<li class="indx">Rocky Mountains, <a href="#Page_88">88</a>, <a href="#Page_89">89</a>, <a href="#Page_180">180</a>.</li>
+
+<li class="indx">Roman Boy, <a href="#Page_34">34</a>.</li>
+
+<li class="indx">Rope, <a href="#Page_20">20</a>, <a href="#Page_26">26</a>.</li>
+
+<li class="indx"><a id="Rose"></a>Rose-leaf, <a href="#Page_63">63</a>, <a href="#Page_70">70</a>.</li>
+<li class="isub1">(See <i><a href="#Willow-leaves">Leaves</a></i>.)</li>
+
+<li class="indx">Rowland’s Photographs, <a href="#Page_237">237</a>.</li>
+
+<li class="indx">Ruskin, quoted, <a href="#Page_29">29</a>.</li>
+
+<li class="indx">Russia, <a href="#Page_134">134</a>.</li>
+
+<li class="indx">Rutherfurd Photographs, <a href="#Page_8">8</a>, <a href="#Page_9">9</a>, <a href="#Page_136">137</a>, <a href="#Page_143">143</a>, <a href="#Page_155">155</a>, <a href="#Page_234">234</a>.</li>
+
+<li class="ifrst">Sal-ammoniac, <a href="#Page_14">14</a>, <a href="#Page_25">25</a>.</li>
+
+<li class="indx">Salisbury Plain, <a href="#Page_1">1</a>, <a href="#Page_2">2</a>.</li>
+
+<li class="indx">Sandstone, <a href="#Page_192">192</a>.</li>
+
+<li class="indx"><a id="Saturn"></a>Saturn, <a href="#Page_118">118</a>, <a href="#Page_118">119</a>, <a href="#Page_121">121</a>, <a href="#Page_123">123</a>, <a href="#Page_124">124</a>, <a href="#Page_127">127–129</a>, <a href="#Page_136">136</a>, <a href="#Page_215">215</a>.</li>
+
+<li class="indx">Saturnian Dwarfs, <a href="#Page_223">223</a>, <a href="#Page_224">224</a>.</li>
+
+<li class="indx">Saul, comparison, <a href="#Page_77">77</a>.</li>
+
+<li class="indx">Saxon Forefathers, <a href="#Page_1">1</a>, <a href="#Page_2">2</a>.</li>
+<li class="isub1">(See <i><a href="#Britain_Ancient">Britain</a></i>.)</li>
+
+<li class="indx"><a id="Scarlet"></a>Scarlet, <a href="#Page_67">67</a>.</li>
+<li class="isub1">(See <i><a href="#Colors">Colors</a></i>.)</li>
+
+<li class="indx">Schwabe, Hofrath, <a href="#Page_76">76</a>, <a href="#Page_77">77</a>, <a href="#Page_87">87</a>.</li>
+
+<li class="indx">Scott, Sir Walter, quoted, <a href="#Page_92">92</a>.</li>
+
+<li class="indx">Screen, <a href="#Page_10">10</a>, <a href="#Page_35">35–37</a>.</li>
+
+<li class="indx">Seas, lunar (<abbr>q. v.</abbr>), <a href="#Page_143">143</a>.</li>
+
+<li class="indx">Secchi, Father, <a href="#Page_14">14</a>, <a href="#Page_14">15</a>, <a href="#Page_24">24</a>, <a href="#Page_25">25</a>, <a href="#Page_29">29</a>, <a href="#Page_30">30</a>, <a href="#Page_43">43</a>, <a href="#Page_59">59</a>, <a href="#Page_235">235</a>.</li>
+
+<li class="indx">Segmentations, <a href="#Page_30">30</a>, <a href="#Page_31">31</a>.</li>
+
+<li class="indx">Self-luminosity, <a href="#Page_215">215</a>.</li>
+
+<li class="indx">Sextant, <a href="#Page_224">224</a>.</li>
+
+<li class="indx">Shadows. (See <i><a href="#Lunar_Shadows">Lunar</a></i>.)</li>
+
+<li class="indx">Shakspeare, quoted, <a href="#Page_60">60</a>, <a href="#Page_220">220</a>.</li>
+
+<li class="indx">Sheaves, <a href="#Page_68">68</a>.</li>
+
+<li class="indx">Shelbyville, <a href="#Page_42">42</a>, <a href="#Page_43">43</a>.</li>
+
+<li class="indx">Sherman, observations at, <a href="#Page_88">88</a>.</li>
+
+<li class="indx">Ship, comparison, <a href="#Page_133">133</a>.</li>
+<li class="isub1">(See <i><a href="#Steamers">Steamer</a></i>.)</li>
+
+<li class="indx"><a id="Shooting-stars"></a>Shooting-stars, <a href="#Page_35">35</a>, <a href="#Page_193">193</a>, <a href="#Page_196">196</a>, <a href="#Page_198">198</a>, <a href="#Page_199">199</a>.</li>
+<li class="isub1">(See <i><a href="#Falling">Falling</a></i>, <i><a href="#Meteors">Meteors</a></i>.)</li>
+
+<li class="indx">Sicily, <a href="#Page_50">50</a>.</li>
+<li class="isub1">(See <i><a href="#Etna">Etna</a></i>.)</li>
+
+<li class="indx">Siemens, Sir William, <a href="#Page_111">111</a>.</li>
+
+<li class="indx">Sierra Nevada, <a href="#Page_151">151</a>, <a href="#Page_160">160</a>, <a href="#Page_180">180</a>.</li>
+
+<li class="indx">Signal Service, <a href="#Page_90">90</a>.</li>
+
+<li class="indx">Silicon, <a href="#Page_107">107</a>.</li>
+
+<li class="indx"><a id="Sirius"></a>Sirius, <a href="#Page_179">179</a>, <a href="#Page_222">222–224</a>, <a href="#Page_236">236–238</a>.</li>
+
+<li class="indx">Slits, <a href="#Page_59">59</a>, <a href="#Page_63">63</a>, <a href="#Page_64">64</a>.</li>
+
+<li class="indx">Smoked Glass, <a href="#Page_11">11</a>.</li>
+
+<li class="indx">Snow-flakes, <a href="#Page_19">19</a>, <a href="#Page_35">35</a>.</li>
+
+<li class="indx">Snow-like Forms, <a href="#Page_25">25</a>.</li>
+
+<li class="indx">Sodium, <a href="#Page_237">237</a>.</li>
+
+<li class="indx"><a id="Solar_Engine"></a>Solar Engine, <a href="#Page_75">75</a>, <a href="#Page_109">109</a>.</li>
+
+<li class="indx"><a id="Solar_Light"></a>Solar Light (<abbr>q. v.</abbr>), <a href="#Page_13">13</a>.</li>
+
+<li class="indx"><a id="Solar_Physics"></a>Solar Physics, <a href="#Page_4">4</a>, <a href="#Page_12">12</a>, <a href="#Page_14">14</a>.</li>
+<li class="isub1">(See <i><a href="#Sun">Sun</a></i>.)</li>
+
+<li class="indx"><a id="Solar_System"></a>Solar System, <a href="#Page_228">228</a>, <a href="#Page_229">229</a>.</li>
+
+<li class="indx"><a id="South_America"></a>South America (<abbr>q. v.</abbr>), <a href="#Page_80">80</a>.</li>
+
+<li class="indx">South Carolina, meteors, <a href="#Page_194">194</a>, <a href="#Page_195">195</a>.</li>
+<li class="isub1">(See <i><a href="#Charleston_Earthquake">Charleston</a></i>.)</li>
+
+<li class="indx">Southern Cross, <a href="#Page_234">234</a>.</li>
+
+<li class="indx">Space, <a href="#Page_181">181</a>, <a href="#Page_211">211</a>, <a href="#Page_224">224</a>, <a href="#Page_227">227</a>, <a href="#Page_229">229</a>.</li>
+
+<li class="indx"><span class="pagenum" id="Page_259">259</span>Spain, expedition, <a href="#Page_44">44</a>.</li>
+
+<li class="indx">Sparks, <a href="#Page_107">107</a>, <a href="#Page_108">108</a>.</li>
+
+<li class="indx">Spectra, <a href="#Page_230">231</a>, <a href="#Page_237">237</a>.</li>
+
+<li class="indx">Spectres, <a href="#Page_54">54</a>, <a href="#Page_55">55</a>.</li>
+<li class="isub1">(See <i><a href="#Brocken_Spectre">Brocken</a></i>.)</li>
+
+<li class="indx">Spectroscope, <a href="#Page_7">7</a>, <a href="#Page_50">50</a>, <a href="#Page_59">59</a>, <a href="#Page_61">61</a>, <a href="#Page_63">63</a>, <a href="#Page_64">64</a>, <a href="#Page_130">130</a>, <a href="#Page_176">176</a>, <a href="#Page_198">198</a>, <a href="#Page_219">219</a>, <a href="#Page_222">222</a>, <a href="#Page_233">233–235</a>, <a href="#Page_241">240</a>.</li>
+
+<li class="indx">Spectrum, <a href="#Page_65">65</a>, <a href="#Page_235">235</a>.</li>
+
+<li class="indx">Spectrum Analysis, <a href="#Page_12">12</a>.</li>
+
+<li class="indx">Speculations, <a href="#Page_193">193</a>.</li>
+
+<li class="indx">Spinning-wheel, <a href="#Page_115">115</a>.</li>
+
+<li class="indx">Springfield Observations, <a href="#Page_44">44</a>.</li>
+
+<li class="indx">Spurs, <a href="#Page_208">208</a>, <a href="#Page_212">212</a>, <a href="#Page_215">215</a>.</li>
+
+<li class="indx">Star of Bethlehem, <a href="#Page_229">229</a>.</li>
+<li class="isub1">(See <i><a href="#Tycho">Tycho</a></i>.)</li>
+
+<li class="indx"><a id="Stars"></a>Stars:</li>
+<li class="isub1">new study, <a href="#Page_3">3</a>;</li>
+<li class="isub1">location, <a href="#Page_4">4</a>;</li>
+<li class="isub1">size, <a href="#Page_4">4</a>, <a href="#Page_230">230</a>;</li>
+<li class="isub1">seen in darkness, <a href="#Page_35">35</a>;</li>
+<li class="isub1">self-shining suns, <a href="#Page_35">35</a>, <a href="#Page_118">118</a>;</li>
+<li class="isub1">host, <a href="#Page_117">117</a>;</li>
+<li class="isub1">variety, <a href="#Page_118">118</a>;</li>
+<li class="isub1">five, <a href="#Page_118">118</a>;</li>
+<li class="isub1">elements, atmosphere, <a href="#Page_179">179</a>;</li>
+<li class="isub1">showers (see <i><a href="#Meteors">Meteors</a></i>), <a href="#Page_195">195</a>;</li>
+<li class="isub1">seen through comet, <a href="#Page_212">212</a>, <a href="#Page_215">215</a>;</li>
+<li class="isub1">chapter, <a href="#Page_221">221–250</a>;</li>
+<li class="isub1">analysis, children, <a href="#Page_222">222</a>;</li>
+<li class="isub1">distances, <a href="#Page_223">223</a>;</li>
+<li class="isub1">intervals, <a href="#Page_224">224</a>, <a href="#Page_227">227</a>, <a href="#Page_229">229</a>;</li>
+<li class="isub1">colors (<abbr>q. v.</abbr>), glory, <a href="#Page_227">227</a>;</li>
+<li class="isub1">new, fading, <a href="#Page_230">230</a>;</li>
+<li class="isub1">double, <a href="#Page_233">233</a>;</li>
+<li class="isub1">relation to man (<abbr>q. v.</abbr>), <a href="#Page_233">233</a>;</li>
+<li class="isub1">fixed, <a href="#Page_233">233</a>;</li>
+<li class="isub1">changing place, <a href="#Page_234">234</a>;</li>
+<li class="isub1">mass, <a href="#Page_237">237</a>;</li>
+<li class="isub1">ages, <a href="#Page_238">238</a>;</li>
+<li class="isub1">photographed, <a href="#Page_244">244</a>, <a href="#Page_247">247</a>;</li>
+<li class="isub1">chart, <a href="#Page_247">247</a>;</li>
+<li class="isub1">death, <a href="#Page_248">248</a>.</li>
+<li class="isub1">(See <i><a href="#Falling">Falling</a></i>, <i><a href="#Planets">Planets</a></i>, <i><a href="#Shooting-stars">Shooting</a></i>.)</li>
+
+<li class="indx">Steam, <a href="#Page_74">74</a>, <a href="#Page_75">75</a>.</li>
+
+<li class="indx"><a id="Steamers"></a>Steamers, <a href="#Page_20">21</a>, <a href="#Page_73">73</a>, <a href="#Page_115">115</a>.</li>
+
+<li class="indx"><a id="Steel"></a>Steel, melted, <a href="#Page_104">104–108</a>.</li>
+<li class="isub1">(See <i><a href="#Iron">Iron</a></i>.)</li>
+
+<li class="indx">Stellar Spectra (<abbr>q. v.</abbr>), <a href="#Page_222">222</a>, <a href="#Page_236">236</a>, <a href="#Page_237">237</a>, <a href="#Page_244">244</a>, <a href="#Page_245">245</a>.</li>
+
+<li class="indx">Stevenson, George, <a href="#Page_111">111</a>.</li>
+
+<li class="indx">Stewart’s Observations, <a href="#Page_88">88</a>.</li>
+
+<li class="indx">Stonehenge, <a href="#Page_1">1–3</a>.</li>
+
+<li class="indx">Stones:</li>
+<li class="isub1">from heaven, <a href="#Page_175">175</a>, <a href="#Page_176">176</a>, <a href="#Page_186">186</a>, <a href="#Page_187">187</a>, <a href="#Page_191">191</a>, <a href="#Page_193">193</a>;</li>
+<li class="isub1">Iowa, <a href="#Page_199">199</a>, <a href="#Page_200">200</a>.</li>
+<li class="isub1">(See <i><a href="#Meteorites">Meteorites</a></i>.)</li>
+
+<li class="indx">Stonyhurst Records, <a href="#Page_88">88</a>.</li>
+
+<li class="indx">Sumbawa Observations, <a href="#Page_181">181</a>.</li>
+
+<li class="indx">Sunbeams:</li>
+<li class="isub1">lifting power, <a href="#Page_72">72</a>;</li>
+<li class="isub1">Laputa, <a href="#Page_73">73</a>;</li>
+<li class="isub1">printing, <a href="#Page_74">74</a>;</li>
+<li class="isub1">motes, <a href="#Page_215">215</a>.</li>
+<li class="isub1">(See <i><a href="#Light">Light</a></i>.)</li>
+
+<li class="indx"><a id="Sun"></a>Sun:</li>
+<li class="isub1">practical observations in Washington, <a href="#Page_2">2</a>, <a href="#Page_3">3</a>;</li>
+<li class="isub1">new study, <a href="#Page_3">3</a>;</li>
+<li class="isub1">surroundings, <a href="#Page_4">4</a>, <a href="#Page_35">35–69</a>;</li>
+<li class="isub1">distance, <a href="#Page_4">4–6</a>;</li>
+<li class="isub1">size, <a href="#Page_5">5</a>, <a href="#Page_6">6</a>;</li>
+<li class="isub1">a private, <a href="#Page_6">6</a>;</li>
+<li class="isub1">views, <a href="#Page_6">6–12</a>, <a href="#Page_14">15</a>, <a href="#Page_17">16</a>, <a href="#Page_20">20</a>;</li>
+<li class="isub1">details, <a href="#Page_7">7</a>;</li>
+<li class="isub1">fire, <a href="#Page_8">8</a>, <a href="#Page_91">91</a>, <a href="#Page_92">92</a>;</li>
+<li class="isub1">telescopic view, <a href="#Page_8">8</a>;</li>
+<li class="isub1">axis, <a href="#Page_9">9</a>;</li>
+<li class="isub1">revolutions, <a href="#Page_10">10</a>;</li>
+<li class="isub1">surface, <a href="#Page_17">17</a>;</li>
+<li class="isub1">paper record, <a href="#Page_18">18</a>;</li>
+<li class="isub1">heat (<abbr>q. v.</abbr>) and eye, <a href="#Page_19">19</a>;</li>
+<li class="isub1">drawings exaggerated, <a href="#Page_29">29</a>, <a href="#Page_30">30</a>;</li>
+<li class="isub1">something brighter, <a href="#Page_32">32</a>;</li>
+<li class="isub1">atmosphere, <a href="#Page_33">33</a>, <a href="#Page_34">34</a>;</li>
+<li class="isub1">slits, <a href="#Page_59">59</a>;</li>
+<li class="isub1">miniature, <a href="#Page_64">64</a>;</li>
+<li class="isub1">flames (<abbr>q. v.</abbr>), <a href="#Page_69">69</a>;</li>
+<li class="isub1">energy, 70–116 (see <i><a href="#Heat">Heat</a></i>);</li>
+<li class="isub1">versatile aid, <a href="#Page_74">74</a>;</li>
+<li class="isub1">children, <a href="#Page_75">75</a>, <a href="#Page_222">222</a>;</li>
+<li class="isub1">shrinkage, <a href="#Page_99">99</a>;</li>
+<li class="isub1">ground up, <a href="#Page_100">100</a>;</li>
+<li class="isub1">emissive power, <a href="#Page_104">104</a>;</li>
+<li class="isub1">constitution and appearance, <a href="#Page_111">111</a>;</li>
+<li class="isub1">god, <a href="#Page_116">116</a>;</li>
+<li class="isub1">self-shining, <a href="#Page_118">118</a>;</li>
+<li class="isub1">studied from mountains, <a href="#Page_167">167</a>;</li>
+<li class="isub1">affected by dust (<abbr>q. v.</abbr>), <a href="#Page_185">185</a>;</li>
+<li class="isub1">and comet, <a href="#Page_216">216</a>;</li>
+<li class="isub1">elements, <a href="#Page_233">233</a>;</li>
+<li class="isub1">a star, <a href="#Page_237">237</a>;</li>
+<li class="isub1">life, <a href="#Page_238">238</a>;</li>
+<li class="isub1">candle, <a href="#Page_249">249</a>;</li>
+<li class="isub1">anecdote, <a href="#Page_250">250</a>.</li>
+<li class="isub1">(See <i><a href="#Solar_Physics">Solar</a></i>.)</li>
+
+<li class="indx">Sunrise, <a href="#Page_234">234</a>.</li>
+
+<li class="indx">Sunset, <a href="#Page_181">181</a>, <a href="#Page_182">182</a>.</li>
+<li class="isub1">(See <i><a href="#Twilight">Twilight</a></i>.)</li>
+
+<li class="indx">Suns:</li>
+<li class="isub1">millions, <a href="#Page_224">224</a>;</li>
+<li class="isub1">dwindling, <a href="#Page_227">227</a>;</li>
+<li class="isub1">periods, <a href="#Page_241">241</a>.</li>
+
+<li class="indx"><a id="Sun-spots"></a>Sun-spots, 1–34 <i xml:lang="la" lang="la">passim</i>;</li>
+<li class="isub1">ancient, <a href="#Page_8">8</a>;</li>
+<li class="isub1">early observations, <a href="#Page_8">8</a>;</li>
+<li class="isub1">changing, <a href="#Page_9">9</a>;</li>
+<li class="isub1">great, <a href="#Page_10">10</a>, <a href="#Page_20">20</a>, <a href="#Page_24">24</a>;</li>
+<li class="isub1">individuality, darker, <a href="#Page_11">11</a>;</li>
+<li class="isub1">leaves (<abbr>q. v.</abbr>), <a href="#Page_11">11</a>, <a href="#Page_12">12</a>;</li>
+<li class="isub1">how observed, <a href="#Page_18">18</a>, <a href="#Page_19">19</a>;</li>
+<li class="isub1">typical, <a href="#Page_20">21</a>, <a href="#Page_23">22</a>;</li>
+<li class="isub1">relative size, <a href="#Page_20">20</a>;</li>
+<li class="isub1">hook-shaped (see <i><a href="#Plume">Plume</a></i>), <a href="#Page_24">24</a>;</li>
+<li class="isub1">signs of chaos, <a href="#Page_27">27</a>;</li>
+<li class="isub1">double, <a href="#Page_32">32</a>;</li>
+<li class="isub1">weather, <a href="#Page_76">76</a>, <a href="#Page_90">90</a>;</li>
+<li class="isub1">periodicity, <a href="#Page_76">76–78</a>;</li>
+<li class="isub1">temperature, <a href="#Page_83">83</a>;</li>
+<li class="isub1">records, <a href="#Page_85">85</a>;</li>
+<li class="isub1">variations, <a href="#Page_87">87</a>;</li>
+<li class="isub1">(1870), <a href="#Page_9">9</a>, <a href="#Page_14">15</a>, <a href="#Page_17">16</a>, <a href="#Page_20">20</a>;</li>
+<li class="isub1">(1873), <a href="#Page_20">20–24</a>;</li>
+<li class="isub1">(1875), <a href="#Page_25">25</a>, <a href="#Page_28">28</a>, <a href="#Page_30">30</a>;</li>
+<li class="isub1">(1876), <a href="#Page_30">30</a>, <a href="#Page_32">32</a>;</li>
+<li class="isub1">(1882), <a href="#Page_80">80</a>, <a href="#Page_83">83–86</a>, <a href="#Page_90">90</a>.</li>
+
+<li class="indx">Superga, <a href="#Page_38">38</a>.</li>
+
+<li class="indx"><a id="Swift_Dean"></a>Swift, Dean, <a href="#Page_73">73</a>, <a href="#Page_131">131</a>, <a href="#Page_132">132</a>.</li>
+<li class="isub1">(See <i><a href="#Gulliver">Gulliver</a></i>.)</li>
+
+<li class="indx">Sword Meteor (<abbr>q. v.</abbr>), <a href="#Page_175">175</a>.</li>
+
+<li class="ifrst">Tacchini’s Investigations, <a href="#Page_43">43</a>, <a href="#Page_49">49</a>, <a href="#Page_62">62</a>, <a href="#Page_66">66</a>, <a href="#Page_68">68</a>.</li>
+
+<li class="indx">Tail, <a href="#Page_215">215</a>, <a href="#Page_216">216</a>.</li>
+<li class="isub1">(See <i><a href="#Comets">Comets</a></i>.)</li>
+
+<li class="indx">Tan, <a href="#Page_71">71</a>.</li>
+
+<li class="indx">Taylor, Bayard, <a href="#Page_139">139</a>.</li>
+
+<li class="indx">Telephone, <a href="#Page_84">84</a>, <a href="#Page_89">89</a>.</li>
+
+<li class="indx">Telescopes:</li>
+<li class="isub1">many, <a href="#Page_17">17</a>;</li>
+<li class="isub1">best, <a href="#Page_134">134</a>;</li>
+<li class="isub1">alone, <a href="#Page_227">227</a>, <a href="#Page_230">230</a>;</li>
+<li class="isub1">use, <a href="#Page_233">233</a>, <a href="#Page_234">234</a>.</li>
+
+<li class="indx">Temperature, <a href="#Page_101">101</a>, <a href="#Page_102">102</a>, <a href="#Page_108">108</a>;</li>
+<li class="isub1">of space, <a href="#Page_224">224</a>, <a href="#Page_227">227</a>.</li>
+
+<li class="indx">Terminator, <a href="#Page_147">147</a>.</li>
+
+<li class="indx">Thermometer, <a href="#Page_71">71</a>, <a href="#Page_93">93</a>, <a href="#Page_102">102</a>;</li>
+<li class="isub1">low, <a href="#Page_160">160</a>, <a href="#Page_163">163</a>.</li>
+
+<li class="indx">Time, small divisions, <a href="#Page_241">241</a>.</li>
+
+<li class="indx">Tippoo Saib, <a href="#Page_221">221</a>.</li>
+
+<li class="indx"><a id="Total_Eclipse"></a>Total Eclipse (<abbr>q. v.</abbr>), 39–48 <i xml:lang="la" lang="la">passim</i>, <a href="#Page_55">55</a>, <a href="#Page_59">59</a>.</li>
+
+<li class="indx">Trees, lacking, <a href="#Page_168">168</a>.</li>
+
+<li class="indx">Tribune, The New York, <a href="#Page_84">84</a>.</li>
+
+<li class="indx">Trinity Church, <a href="#Page_72">72</a>.</li>
+
+<li class="indx">Trocadéro, <a href="#Page_112">112</a>.</li>
+
+<li class="indx">Trouvelot, E. L., <a href="#Page_118">119</a>, <a href="#Page_123">123</a>, <a href="#Page_224">225</a>.</li>
+
+<li class="indx">Turin, <a href="#Page_38">38</a>.</li>
+
+<li class="indx"><a id="Twilight"></a>Twilight, small, <a href="#Page_38">38</a>.</li>
+
+<li class="indx"><a id="Tycho"></a>Tycho, <a href="#Page_144">144</a>, <a href="#Page_229">229</a>.</li>
+<li class="isub1">(See <i><a href="#Stars">Star</a></i>.)</li>
+
+<li class="indx">Tyndall, <a href="#Page_98">98</a>.</li>
+
+<li class="ifrst">Umbra, <a href="#Page_11">11</a>, <a href="#Page_12">12</a>, <a href="#Page_19">19</a>, <a href="#Page_20">20</a>.</li>
+
+<li class="indx">United States, comparison, <a href="#Page_24">24</a>.</li>
+
+<li class="indx"><span class="pagenum" id="Page_260">260</span>Uranus, <a href="#Page_3">3</a>, <a href="#Page_196">196</a>.</li>
+
+<li class="indx">Vapor, <a href="#Page_28">28</a>.</li>
+
+<li class="indx">Vega, <a href="#Page_235">235</a>, <a href="#Page_246">246</a>.</li>
+
+<li class="indx">Vegetables, <a href="#Page_74">74</a>.</li>
+
+<li class="indx">Veils, <a href="#Page_14">14</a>, <a href="#Page_17">17</a>.</li>
+
+<li class="indx">Venus, <a href="#Page_118">118</a>.</li>
+
+<li class="indx">Vernier, <a href="#Page_3">3</a>.</li>
+
+<li class="indx"><a id="Vesuvius"></a>Vesuvius:</li>
+<li class="isub1">crater, <a href="#Page_155">155</a>, <a href="#Page_156">157</a>;</li>
+<li class="isub1">eruption, <a href="#Page_181">181</a>, <a href="#Page_182">183</a>.</li>
+<li class="isub1">(See <i><a href="#Naples">Naples</a></i>.)</li>
+
+<li class="indx">Vibrations, <a href="#Page_72">72</a>.</li>
+
+<li class="indx">Victoria, <a href="#Page_115">115</a>.</li>
+
+<li class="indx">Viscous Fluid, <a href="#Page_26">26</a>.</li>
+
+<li class="indx">Vital Force, <a href="#Page_14">14</a>.</li>
+
+<li class="indx">Vogel, H. C., <a href="#Page_64">64</a>, <a href="#Page_66">66</a>.</li>
+
+<li class="indx">Voids, <a href="#Page_181">181</a>, <a href="#Page_227">227</a>.</li>
+
+<li class="indx">Volcanoes, <a href="#Page_27">27</a>, <a href="#Page_28">28</a>;</li>
+<li class="isub1">in moon, <a href="#Page_167">167</a>, <a href="#Page_193">193</a>.</li>
+
+<li class="ifrst">Wandering Star, <a href="#Page_101">101</a>.</li>
+<li class="isub1">(See <i><a href="#Comets">Comets</a></i>, <i><a href="#Falling">Falling</a></i>.)</li>
+
+<li class="indx">Washington:</li>
+<li class="isub1">Observatory, <a href="#Page_2">2</a>, <a href="#Page_86">86–88</a>;</li>
+<li class="isub1">telescope, <a href="#Page_122">122</a>;</li>
+<li class="isub1">Monument, <a href="#Page_182">182</a>.</li>
+
+<li class="indx">Water, <a href="#Page_152">152</a>;</li>
+<li class="isub1">in man, <a href="#Page_221">221</a>.</li>
+
+<li class="indx">Waterloo, <a href="#Page_80">80</a>.</li>
+
+<li class="indx">Water-wheel, <a href="#Page_111">111</a>.</li>
+
+<li class="indx">Watson’s Observations, <a href="#Page_49">49</a>.</li>
+
+<li class="indx"><a id="Wheat"></a>Wheat, prices, <a href="#Page_79">79</a>.</li>
+<li class="isub1">(See <i><a href="#Breadstuffs">Breadstuffs</a></i>, <i><a href="#Corn">Corn</a></i>, <i><a href="#Grain">Grain</a></i>, <i><a href="#Sun-spots">Sun-spots</a></i>.)</li>
+
+<li class="indx">Wheel, comparison, <a href="#Page_10">10</a>.</li>
+
+<li class="indx">Whirlpools, <a href="#Page_28">28</a>, <a href="#Page_31">31</a>.</li>
+
+<li class="indx">Whirlwinds, <a href="#Page_23">23</a>, <a href="#Page_31">31</a>.</li>
+
+<li class="indx">White Light (<abbr>q. v.</abbr>), <a href="#Page_48">48</a>, <a href="#Page_62">62</a>, <a href="#Page_63">63</a>.</li>
+
+<li class="indx">Whitney, Mount, <a href="#Page_176">177</a>.</li>
+
+<li class="indx"><a id="Willow-leaves"></a>Willow-leaves (<abbr>q. v.</abbr>), <a href="#Page_11">11</a>, <a href="#Page_12">12</a>, <a href="#Page_14">14</a>.</li>
+
+<li class="indx">Wing, simile, <a href="#Page_215">215</a>.</li>
+
+<li class="indx">Winlock, Professor, <a href="#Page_44">44</a>.</li>
+
+<li class="indx">Withered Surfaces, <a href="#Page_168">168</a>, <a href="#Page_171">171</a>.</li>
+
+<li class="indx">Wood-engraving, <a href="#Page_50">50</a>.</li>
+
+<li class="indx">Worlds and Clouds, <a href="#Page_249">249</a>.</li>
+
+<li class="indx">Wrinkles, <a href="#Page_172">172</a>.</li>
+
+<li class="ifrst">Xeres, Spain (<abbr>q. v.</abbr>), <a href="#Page_44">44</a>, <a href="#Page_53">53</a>.</li>
+
+<li class="ifrst">Young, Professor:</li>
+<li class="isub1">spectroscope, <a href="#Page_44">44</a>, <a href="#Page_50">50</a>, <a href="#Page_65">65</a>, <a href="#Page_234">234</a>;</li>
+<li class="isub1">observations, <a href="#Page_56">56</a>, <a href="#Page_59">59</a>, <a href="#Page_61">61</a>, <a href="#Page_68">68</a>, <a href="#Page_69">69</a>;</li>
+<li class="isub1">magnetism, <a href="#Page_87">87</a>, <a href="#Page_88">88</a>;</li>
+<li class="isub1">radiation, <a href="#Page_101">101</a>.</li>
+
+<li class="ifrst">Zodiacal Light, <a href="#Page_55">55</a>.</li>
+</ul>
+</div></div>
+
+<p class="p2 center smaller">University Press: John Wilson &amp; Son, Cambridge.</p>
+
+<div class="chapter"><div class="transnote">
+<h2 class="nobreak p1" id="Transcribers_Notes">Transcriber’s Notes</h2>
+
+<p>Punctuation, hyphenation, and spelling were made
+consistent when a predominant preference was found
+in the original book; otherwise they were not changed.</p>
+
+<p>Simple typographical errors were corrected; unbalanced
+quotation marks were remedied when the change was
+obvious, and otherwise left unbalanced.</p>
+
+<p>Illustrations in this eBook have been positioned
+between paragraphs and outside quotations. In versions
+of this eBook that support hyperlinks, the page
+references in the List of Illustrations lead to the
+corresponding illustrations.</p>
+
+<p>The index was not checked for proper alphabetization or correct page
+references. References to unnumbered pages (usually images) have been
+linked to adjacent numbered pages.</p>
+
+</div></div>
+
+<div style='display:block; margin-top:4em'>*** END OF THE PROJECT GUTENBERG EBOOK THE NEW ASTRONOMY ***</div>
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author	nfenwick <nfenwick@pglaf.org>	2025-01-23 09:21:47 -0800
committer	nfenwick <nfenwick@pglaf.org>	2025-01-23 09:21:47 -0800
commit	6fd35756d02769f0d93a649f4fa2504ba53f6194 (patch)
tree	33a9e60361be3bf88729afa77e58fe1c435f88ff