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+Project Gutenberg (https://www.gutenberg.org) public repository for
+eBook #64577 (https://www.gutenberg.org/ebooks/64577)
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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
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-Punctuation, hyphenation, and spelling were made consistent when a
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-
-<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>
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